Patent Publication Number: US-2018042766-A1

Title: Nozzle

Description:
TECHNICAL FIELD 
     One or more embodiments of the present invention relate to a nozzle provided in a pouring part of a container for instillation of eye drops, for example, which is capable of dripping a liquid inside a container little by little. 
     BACKGROUND ART 
     Generally, in a container for instillation of eye drops, etc., a nozzle is provided in the pouring part so that the liquid (eye drops) in the container can be dripped little by little. 
     Here, usually, the human eye has a volume to hold about 20 μl of a tear fluid, but with a nozzle of a conventional container for instillation of eye drops, the dripping quantity of one droplet is generally about 30 to 40 μl, and almost half of the dripped eye drops are overflown from the eye. 
     Therefore, proposals have been made on a nozzle of a container for instillation of eye drops that enables dripping of eye drops in a smaller quantity corresponding to the tear-retaining volume of such human eyes. 
     In Patent Document 1, proposed is “an instillation container” in which the front end of the dispensing nozzle for dripping eye drops from the container is provided with a needle part having an outer diameter of 0.5 mm or more and 2.5 mm or less such that the dripping quantity of one drop can be about 5 to 25 μl. 
     Further, Patent Document 2 proposes a “container for a liquid having a water-repellent nozzle” in which a liquid-repellent substance is applied to a nozzle tip sealed part inside the cap of the chemical solution container and when the container is closed, the liquid-repellent substance is transferred to the nozzle side, whereby the front end of the nozzle has liquid repellency, thereby enabling control the dripping quantity of one drop. 
     RELATED ART DOCUMENTS 
     Patent Documents 
     Patent Document 1: WO2014/123140 
     Patent Document 2: JP-A-2011-105339 
     In the “instillation container” described in Patent Document 1, a small needle part is provided at the front end of the nozzle so as to reduce the quantity of dripping. However, there is no liquid-repellent performance on the needle part itself, and droplets adhere to and remain on the nozzle front end part including a needle part while dripping is performed, and stable quantitative dripping cannot be performed as it is used repeatedly. 
     Further, a fine needle of 0.5 to 2.5 mm has a possibility of giving a user who uses an eye drop a fear that the needle pierces the eye since the front end looks very pointy. 
     Also, even with such a fine needle, the dripping quantity is limited to about 10 μl at most and, hence it cannot be said that it is sufficient in respect of small-quantity dripping. 
     On the other hand, in the “liquid container” described in Patent Document 2, a liquid-repelling substance is applied to the front end of the nozzle via a cap, and a substance different from the eye drop is applied to the front end of the nozzle of the eye drop container. Therefore, there may be contamination due to the entering of foreign matters into the container and adverse effects on the human body. Further, as in the case of Patent Document 1, stable quantitative dripping cannot be conducted after repeated use. 
     Therefore, for a container for instillation of eye drops, it was thought that practical implementation was impossible. 
     SUMMARY 
     One or more embodiments of the present invention provide a nozzle that realizes reduction in dripping quantity in a container for instillation of eye drops, which can prevent liquid dripping or presence of residual liquid on the nozzle top surface, and is free from contamination of a nozzle front end, mixing in of foreign matters or microorganism due to returning of a liquid from the nozzle to the container main body, and deterioration of dripping performance, etc. Hence, stable small-quantity dripping can be conducted stably without causing variations in dripping quantity, and further, the nozzle front end can be protected without fail. 
     In one or more embodiments, the nozzle of the present invention relates to a nozzle composed of a non-fluorine-based resin, wherein fluorine atoms are incorporated into a molecular chain of the non-fluorine-based resin constituting a surface of the nozzle. 
     Further, the nozzle according to one or more embodiments of the present invention is a nozzle wherein a surface of a front end part of the nozzle is provided with a first surface positioned nearer to the center of the nozzle and a second surface continuing to the outer peripheral side of the first surface, and the first surface and the second surface are composed of surfaces differing in surface free energy. 
     According to one or more embodiments of the present invention, reduction in dripping quantity in a container for instillation of eye drops is realized, liquid dripping or presence of a residual liquid on the nozzle top surface can be prevented, contamination of the nozzle front end, mixing in of foreign matters or microorganisms due to returning of a liquid from the nozzle to the container main body, deterioration in dripping performance due to repeated use, etc. can be eliminated. Also, occurrence of deterioration in dripping performance by repeated use can be prevented. 
     In addition, no variations in dripping quantity are caused, and small-quantity dripping can be conducted stably without fail, and further, the nozzle front end part can be protected by a cap without fail. 
     Due to such advantageous effects, a nozzle for a container for instillation of eye drops can be realized, for example. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIGS. 1( a ) and 1( b )  show a nozzle according to one or more embodiments of the present invention.  FIG. 1( a )  is a cross-sectional view of an entire container for instillation of eye drops, and  FIG. 1( b )  is an enlarged cross-sectional view of a front end part of the nozzle shown in  FIG. 1( a ) . 
         FIGS. 2( a ) and 2( b )  show a nozzle according to one or more embodiments of the present invention.  FIG. 2( a )  is a cross-sectional view of the entire container for instillation of eye drops, and  FIG. 2( b )  is an enlarged cross-sectional view of a front end part of the nozzle shown in  FIG. 2( a ) ; 
         FIGS. 3( a ) and 3( b )  are explanatory views schematically showing a state of liquid droplets of a nozzle according to one or more embodiments of the present invention, in the presence or absence of liquid-repellent treatment.  FIG. 3( a )  shows a case of a nozzle which is not subjected to a liquid-repellent treatment, and  FIG. 3( b )  shows a case of a nozzle which is subjected to a liquid-repellent treatment. 
         FIGS. 4( a )-4( d )  are explanatory diagrams schematically showing a variation in the quantity of dripping in a nozzle according to one or more embodiments of the present invention, which is subjected to a liquid-repellent treatment.  FIG. 4( a )  shows a normal case,  FIG. 4( b )  shows a case where liquid repellency is biased,  FIG. 4( c )  shows a case where air is entrained in liquid droplets, and  FIG. 4( d )  shows a case where circumferential protruded parts (burr) are present on an opening of a nozzle subjected to a liquid-repellent treatment. 
         FIGS. 5( a )-5( h )  are explanatory views schematically showing first/second surfaces of a nozzle front end part according to one or more embodiments of the present invention. Fig. (a) shows a case in which a cylindrical first dripping part is allowed to protrude from the front end of a second dripping part positioned on its outer periphery to constitute the first/second surfaces;  FIG. 5( b )  shows a case where the area of the first surface is enlarged by allowing the cylindrical part constituting the first dripping part shown in  FIG. 5( a )  to have an increased thickness;  FIG. 5( c )  shows a case where the side surface of the first dripping part shown in  FIG. 5( b )  is subjected to a liquid-repellent treatment as in the case of the second surface;  FIG. 5( d )  shows a case where the first/second surfaces are constituted without protruding the first dripping part from the front end of the second dripping part;  FIG. 5( e )  shows a case where the front end of the first dripping part shown in  FIG. 5( a )  is tapered and the first surface is inclined towards the dripping direction;  FIG. 5( f )  shows a case where the front end of the first dripping part shown in  FIG. 5( a )  is formed in a trumpet form, thereby to enlarge the area of the first surface and to allow it to be protruded to the second surface side;  FIG. 5( g )  shows a case where the first/second surfaces are integrally formed on the front end side of the second dripping part; and  FIG. 5( h )  shows a case where a first dripping part is constituted by using a fiber member, an unwoven fabric, etc. instead of the first cylindrical dripping part shown in  FIG. 5( a ) . 
         FIGS. 6( a ) and 6( b )  are explanatory views schematically showing the first/second surfaces of the nozzle front part according to one or more embodiments of the present invention.  FIG. 6( a )  shows a case where the first dripping part in which the inner surface of the front end part is chamfered is arranged without being protruded from the front end of the second dripping part, thereby allowing the part with a chamfered shape to be a first surface; and  FIG. 6( b )  shows a case where the first surface in a chamfered shape shown in  FIG. 6( a )  is integrally formed with the second surface on the front end part of the second dripping part. 
         FIG. 7  is an explanatory view schematically showing the morphology of the liquid-repellent roughened surface formed on the front end part of the nozzle according to one or more embodiments of the present invention; 
         FIGS. 8( a ) and 8( b )  are explanatory views schematically showing the contact pattern of liquid droplets on the roughened surface shown in  FIG. 7  in the Cassie-Baxter model and the Wenzel model, respectively. 
         FIG. 9  is an explanatory enlarged view showing another morphology of a roughened surface formed on the front end part of the nozzle according to one or more embodiments of the present invention; 
         FIG. 10  is an explanatory enlarged view showing the morphology of a roughened surface formed on the front end part of the nozzle according to one or more embodiments of the present invention; 
         FIGS. 11( a ) and 11( b )  are views showing a cap covering the nozzle according to one or more embodiments of the present invention.  FIG. 11( a )  is a cross-sectional view of essential part of the container for instillation of eye drops with the cap being attached; and  FIG. 11( b )  is an enlarged cross-sectional view of the front end part of the nozzle of the cap shown in  FIG. 11( a ) . 
         FIGS. 12( a )-12( c )  are views showing another morphology of a cap according to one or more embodiments of the present invention.  FIG. 12( a )  is a cross-sectional view of an essential part of the container for instillation of eye drops with the cap being detached; and  FIG. 12( b )  is an enlarged cross-sectional view of the container for instillation of eye drops with the cap being attached; and  FIG. 12( c )  is an enlarged cross-sectional view of the front end part of the nozzle of the cap shown in  FIG. 12( b ) ; 
         FIGS. 13( a ) and 13( b )  show a cap covering the nozzle according to one or more embodiments of the present invention.  FIG. 13( a )  is a cross-sectional view of an essential part of the container for instillation of eye drops with the cap being attached; and  FIG. 13( b )  is an enlarged cross-sectional view of the front end part of the nozzle of the cap shown in  FIG. 13( a ) ; 
         FIGS. 14( a )-14( c )  show another morphology of the cap covering the nozzle according to one or more embodiments of the present invention.  FIG. 14( a )  is a cross-sectional view of an essential part of the container for instillation of eye drops with the cap being detached; and  FIG. 14( b )  is an enlarged cross-sectional view of the container for instillation of eye drops with the cap being attached; and  FIG. 14( c )  is a cross-sectional view of the front end part of the nozzle of the cap shown in  FIG. 14( b ) ; 
         FIGS. 15( a ) and 15( b )  are still another morphology of the cap covering the nozzle according to one or more embodiments of the present invention.  FIG. 15( a )  is a cross-sectional view of an essential part of the container for instillation of eye drops with the cap being attached; and  FIG. 15( b )  is an enlarged cross-sectional view of the front end part of the nozzle of the cap shown in  FIG. 15( a ) ; 
         FIGS. 16( a ) ( 1 )- 16 ( a )( 3 ) and  FIGS. 16( b ) ( 1 )- 16 ( b )( 3 ) are explanatory views schematically showing the method for producing a nozzle according to one or more embodiments of the present invention.  FIGS. 16( a ) ( 1 )- 16 ( a )( 3 ) show a case where common injection molding is used, and  FIGS. 16( b ) ( 1 )- 16 ( b )( 3 ) show a case where injection compression molding or heat &amp; cool type injection molding is used. 
         FIG. 17  is an explanatory view schematically showing the method for fluorine plasma etching treatment for roughening the front end part of the nozzle according to one or more embodiments of the present invention. 
         FIGS. 18( a ) ( 1 )- 18 ( a )( 4 ) and  FIGS. 18( b ) ( 1 )- 18 ( b )( 4 ) are explanatory views schematically showing the method for producing the nozzle according to one or more embodiments of the present invention.  FIGS. 18( a ) ( 1 )- 18 ( a )( 4 ) show a case where common injection molding is used; and  FIGS. 18( b ) ( 1 )- 18 ( b )( 4 ) show a case where injection compression molding or heat &amp; cool type injection molding is used; 
         FIGS. 19 ( 1 )- 19 ( 4 ) are explanatory views schematically showing the method for producing the nozzle according to one or more embodiments of the present invention.  FIGS. 19 ( 1 )- 19 ( 4 ) show a case where, in the production method shown in  FIGS. 18( a ) ( 1 )- 18 ( a )( 4 ), a first surface with a chamfered shape is formed on the front end opening of the second dripping part without using the first dripping part; 
         FIGS. 20( a ) and 20( b )  are plane views and cross-sectional views taken along the line A-A thereof of the front end part when a bulwark is provided on the periphery of the opening of the nozzle according to one or more embodiments of the present invention.  FIG. 20( a )  shows a case where a bulwark is provided on the periphery of the opening, and  FIG. 20( b )  shows a case where a bulwark is not provided. 
         FIGS. 21( a )-21( c )  are partial cross-sectional views of the nozzle in which a thick wall part is provided on the outer periphery of the front end part of the nozzle, according to one or more embodiments of the present invention.  FIG. 21( a )  shows a case where the thick wall part is overhung relative to the top surface of the nozzle front end part;  FIG. 21( b )  shows a case where the thick wall part is slanted relative to the top surface of the nozzle front end part; and  FIG. 21( c )  shows a nozzle in which no thick wall part is provided. 
         FIGS. 22( a )-22( c )  are partial cross-sectional views of the nozzle in which a thick wall part is provided on the outer periphery of the front end part of the nozzle according to one or more embodiments of the present invention.  FIG. 22( a )  shows a case where the thick wall part is overhung relative to the top surface of the nozzle front end part;  FIG. 22( b )  shows a case where the thick wall part is slanted relative to the top surface of the nozzle front end part; and  FIG. 22( c )  shows a nozzle in which no thick wall part is provided. 
         FIGS. 23( a ) and 23( b )  are cross-sectional views of an essential part of the nozzle according to one or more embodiments of the present invention, for explaining the drainability when a slanted thick wall part is provided on the outer periphery of the nozzle front end part. 
         FIG. 24  is a cross-sectional view of an essential part of the nozzle according to one or more embodiments of the present invention, for explaining the drainability when an overhung thick wall part is provided on the outer periphery of the nozzle front end part. 
         FIGS. 25( a )-25( c )  are explanatory views schematically showing the method for producing a thick wall part by heat pressing in the nozzle according to one or more embodiments of the present invention.  FIG. 25( a )  shows a state prior to heat pressing in which the opening (discharge port) of the nozzle is made large in advance such that it is not blocked by heat pressing;  FIG. 25( b )  shows a state after heat pressing; and  FIG. 25( c )  shows a state in which the opening of the nozzle is blocked by heat pressing. 
     
    
    
     DETAILED DESCRIPTION OF THE EMBODIMENTS 
     Herein below, one or more embodiments of the nozzle of the present invention will be explained with reference to the drawings. 
       FIG. 1  shows a nozzle according to one or more embodiments of the present invention, in which (a) is a cross-sectional view of an entire container for instillation of eye drops, and (b) is an enlarged cross-sectional view of a front end part of the nozzle shown in (a). 
     Similarly,  FIG. 2  shows a nozzle according to one or more embodiments of the present invention, in which (a) is a cross-sectional view of the entire container for instillation of eye drops, and (b) is an enlarged cross-sectional view of a front end part of the nozzle shown in (a). 
     [Container for Instillation for Eye Drops] 
     As shown in  FIG. 1 , the nozzle according to one or more embodiments of the present invention constitutes a nozzle  10  that serves as a pouring port of a container  1  for instillation of eye drops. 
     Specifically, the container  1  for instillation of eye drops includes a container main body  2  capable of accommodating and storing a liquid serving as an eye drop in the inside thereof, and nozzles  10  ( 10 A,  10 B) that protrude from almost the center of the upper surface (bottom surface when an eye drop is dripped) of this container main body  2 . The container main body  2  and the nozzle  10  are intercommunicated, whereby the eye drops stored in the container main body  2  can be poured and dripped from the opening at the front end part of the nozzle  10 . 
     [Nozzle] 
     As shown in  FIG. 1  and  FIG. 2 , the nozzles  10  ( 10 A,  10 B) are formed separately from the container main body  2 , and inserted into and engaged with a protruded part for attaching a nozzle formed in the container main body  2  to be integrated with the container main body  2  to form the container  1  for instillation of eye drops. 
     Specifically, the nozzle  10  is formed in a cylindrical shape, for example, and is intercommunicated with the storing space of the container main body  2 . Then, through the opening of the front end part of the cylindrical nozzle  10 , a liquid is poured and dropped from the inside of the container main body  2 . 
     Further, in the container main body  2  including the nozzle  10 , a cap  20  mentioned later is detachably attached (see  FIGS. 11 to 15 ). By provision of such cap  20 , the nozzle  10  is covered and the inside of the container main body  2  is sealed and the front end part of the nozzle  10  is protected. 
     Specifically, on the surface of the protruded part of the container main body  2  on which the nozzle  10  is attached, a screw structure that screws with the inner surface of the cap  20  is provided, whereby the cap  20  is detachably attached by screwing to the container main body  2 , and the container main body  2  is sealed in a state that the cap  20  is attached. 
     As mentioned later, in the nozzle  10 A according to the first embodiment, as shown in  FIG. 1 , the side surface part  12 A continuing the front end part  11 A of the nozzle  10 A is formed in a tapered shape that inclines towards the front end part  11 A, and the container main body  2  is sealed when this side surface  12 A contacts and is pressed by the liner  21  of the cap  20 . 
     On the other hand, in the nozzle  10 B according to the second embodiment, as shown in  FIG. 2 , the side surface part  12 Bb of the second dripping part  12 B that constitutes the front end part of the nozzle  10 B is formed in a tapered shape that inclines towards the front end. The side surface part  12 Bb of the second dripping part  12 B and the front end part of the first dripping part  11 B (first surface  11 Ba) contacts with and is pressed by a liner  21  on the inside of the cap  20 , whereby the entire container main body  2  is sealed. 
     For the details of the cap  20 , an explanation will be made later with reference to  FIGS. 11 to 15 . 
     The container main body  2  and the nozzle  10 , including a cap  20  mentioned later, are formed of a prescribed plastic material. 
     The plastic material forming the container main body  2  and the nozzle  10  is not particularly restricted, and can be formed of various thermoplastic resins (e.g. olefin-based resin such as polyethylene and polypropylene) or a polyester resin represented by polyethylene terephthalate (PET). 
     In particular, as for the nozzle  10  according to one or more embodiments of the present invention, as mentioned later, on the surface of the nozzle front end part (front end part  11 A, second surface  12 Ba), a roughened surface  100  composed of concavo-convex surface is formed (see  FIGS. 7 to 10 ). Therefore, in respect of shape stability, strength, etc. of the roughened surface  100 , a polyolefin-based resin such as polyethylene and polypropylene which is a non-fluorine-based resin) may be used. 
     By using such plastic resin material, the container main body  2  and the nozzle  10  can be formed by using a known technology such as injection molding. 
     Since the container main body  2  and the nozzle  10  are formed as separate bodies (separate parts), the container main body  2  can also be formed of a non-plastic material such as glass or metal. In addition, the container main body  2  and the nozzle  10  can be integrally formed by integral molding such as a blow-fill seal molding method. 
     The method for molding the nozzle  10  of the present embodiment will be explained later with reference to  FIGS. 16, 18 to 20 . 
     [Liquid-Repellency Treatment] 
     In the nozzle  10  according to one or more embodiments of the present invention, by applying a predetermined liquid-repellency treatment to the nozzle front end part, the liquid contained in the container body  2  can be reliably and stably poured and dripped from the nozzle front end part in a desired quantity of droplets. 
       FIG. 3  is an explanatory view schematically showing a state of liquid droplets of a nozzle according to the presence or absence of liquid-repellent treatment, in which (a) shows a case where a nozzle is not subjected to a liquid-repellent treatment, and (b) shows a case where a nozzle is subjected to a liquid-repellent treatment; 
     First, as shown in  FIG. 3( a ) , if the surface of the front end part of the nozzle is not subjected to a liquid-repellency treatment yet (e.g. the surface of a bulk plastic resin as it is), since the liquid repellency of the surface is “low”, droplets poured from the nozzle are adhered to the surface of the nozzle front end part and are spread almost hemispherically. The liquid spreading to the front end of the nozzle does not separate from the nozzle surface unless the amount becomes considerable. As a result, if more droplets than desired are dripped and spread to such a degree that the inner diameter of the nozzle can be ignored, it becomes difficult to control the quantity of liquid droplets depending on the inner diameter of the nozzle. 
     On the other hand, as shown in  FIG. 3( b ) , in the case where the surface of the front end part of the nozzle is subjected to a liquid-repellent treatment, if the surface of a plastic resin is subjected to a fluorinating treatment or a surface roughing treatment, since the liquid repellency of the surface is “high”, the droplets poured from the nozzle become almost spherical without wetting and spreading the front end of the nozzle. Then, when the weight of the droplets becomes higher than the adhesiveness between the liquid droplets and the nozzle front end part, the liquid droplets are removed from the nozzle surface and fall down and are dripped. Since the droplets do not spread while wetting, the adhesiveness is low, and only a small quantity of droplets are dripped. Further, by setting the inner diameter of the nozzle to a prescribed dimension, it is possible to pour and drip a prescribed quantity of liquid droplets. 
     However, even when the nozzle surface is fluorinated or roughened to increase the liquid repellency, there may be a case that there are variations in the dripping quantity of the poured droplets. 
       FIG. 4  is an explanatory view schematically showing variations in dripping quantity in a nozzle of which the surface of the front end surface is subjected to a liquid-repellency treatment. 
     First, liquid droplets dripped from a nozzle of which the front end surface is subjected to a liquid-repellency treatment, if normal, become spherical at the middle of the opening of the nozzle front end, as shown in  FIG. 4( a ) , and the weight of liquid droplets reach a prescribed level, they are removed from the nozzle front end and fall down and dripped. 
     However, when the liquid repellency of the nozzle surface subjected to a liquid-repellent treatment is biased, liquid droplets poured from the nozzle move to a side with a lower liquid repellency, and as shown in  FIG. 4 ( b ) , the state is deviated from the center of the nozzle opening. In such a state, since the droplet becomes larger than as compared with the normal case, the quantity of liquid droplets dripped becomes larger than that in the normal case. 
     Further, when a liquid is poured out of the nozzle, the so-called entrainment of air (i.e. the bubbles are generated and mixed in the liquid) may occur. When such entrainment of air occurs, liquid droplets poured from the nozzle are separated into a plurality of liquid droplets having different liquid quantities as shown in  FIG. 4 ( c ) , for example. As these plural droplets are dripped individually or as an integrated droplet, the quantity of dripping may be different from that in the normal case. 
     On the other hand, when a water repellency treatment is conducted for the front end part of a nozzle, further as shown in  FIG. 4( d ) , if a protruded part that protrudes from the front end surface (a peripheral protruded part (burr) shown in  FIG. 4( d ) ) is present on the outer periphery of the nozzle front end, it becomes possible to prevent variations in dripped quantity as mentioned above. 
     That is, due to the presence of a protruded part on the outer periphery of the opening of the nozzle, liquid droplets poured from the nozzle do not contact the nozzle front end, and become spherical in a state that contacts only the front end part of the protruded part. Therefore, liquid droplets are inducibly formed on the middle of the opening of the front end of the nozzle, and hence, it is possible to prevent liquid droplets being poured on biased positions of the nozzle front end surface, and also possible to prevent liquid droplets from pouring after being separated into plural droplets due to presence of bubbles or the like in droplets poured. Therefore, biasing or variations of liquid droplets as shown in  FIGS. 4( b ) and ( c )  does not occur, whereby a prescribed quantity of liquid droplets can be poured and dripped. 
     In the present embodiment, based on this principle, first, by imparting a prescribed liquid-repellent treatment and liquid-repellent structure to the front end part of the nozzle  10  through which a liquid is poured from the container main body  20 , liquid repellency of the front end surface of the nozzle  10  is enhanced. 
     From the viewpoint of eliminating variations in dripping quantity due to variations in liquid repellency of the nozzle surface or entrainment of air or the like, it is desirable to positively create biased liquid repellency so that droplets are formed on the center of the nozzle  10  without fail. A surface having lower liquid repellency than that of the nozzle surface which is subjected to a liquid-repellent treatment is provided at the center of the nozzle. 
     Specifically, the nozzle  10  of one or more embodiments of the present invention can be implemented as the nozzle  10 A according to the first embodiment and the nozzle  10 B according to the second embodiment shown below (see  FIGS. 1 and 2 ). 
     First Embodiment 
     In the nozzle  10 A of the first embodiment, the surface of the front end part  11 A of the nozzle  10 A is fluorinated and roughened by a predetermined method. 
     First, in the nozzle  10 A formed of a plastic molded body made of a non-fluorine-based resin, fluorine atoms are incorporated in a molecular chain of the non-fluorine-based resin constituting the plastic molded body. 
     Further, the surface of the front end part  11 A of the nozzle  10 A that is fluorinated as mentioned above can be roughened according to need. 
     By fluorinating and roughing the front end part  11 A of the nozzle  10 A, the water repellency of the nozzle  10 A can be enhanced (see  FIGS. 3 and 4 ), a liquid (eye drop) poured from the container main body  2  is prevented from wetting a large range of the front end part  11 A of the nozzle  10 A, and by adjusting and setting the inner diameter of the opening  11 Aa, the dripping quantity of a liquid poured from the nozzle  10 A can be arbitrarily set. 
     As mentioned above, in the first embodiment, by fluorinating and roughing the front end part  11 A of the nozzle  10 A, a prescribed liquid-repellent treatment and liquid-repellent structure are imparted to the front end part  11 A of the nozzle  10 A from which a liquid is poured from the container main body  2 . 
     Regarding the operation principle of the liquid repellency structure by fluorinating and roughing the front end  11 A of the nozzle  10 A of the present embodiment, and an explanation will be made later with reference to  FIGS. 7 to 10 . 
     By increasing the liquid repellency of the nozzle  10 A in this way, it is possible to pour and drip a liquid in a desired dripping quantity (for example, 10 μl or less) according to the inner diameter of the opening  11 Aa of the nozzle  10 A. 
     Further, the nozzle  10 A thus subjected to a liquid-repellent treatment is protected by a cap  20  described later, so that breakage, deterioration or the like of the roughened structure of the front end part  11 A of the nozzle  10 A do not occur. 
     As described later, the front end part  11 A of the nozzle  10 A may be fluorinated and that the surface of the front end part  11 A be roughened in respect of improving liquid repellency. 
     However, as long as the front end part  11 A of the nozzle  10 A is at least fluorinated, liquid repellency can be imparted to the nozzle  10 A made of a non-fluorine-based resin. Further, as mentioned later, a plasma treatment (see  FIG. 20 ) in order to impart the front end part  11 A to be fluorinated is significantly strong, and hence, fine concavities and convexities are formed on the surface of the front end part  11 A of the nozzle  10 A by a plasma treatment, whereby the surface is roughened. 
     Accordingly, in the nozzle  10 A according to the present embodiment, it suffices that at least the front end part  11 A is fluorinated, and if necessary, it suffices that the surface of the front end part  11 A is roughened. 
     Second Embodiment 
     The basic configuration, material, or the like of the nozzle  10 B according to the second embodiment are the same as those of the nozzle  10 A according to the first embodiment mentioned later. 
     As for the nozzle  10 B according to the second embodiment, the constitution of the nozzle front end part differs from that of the nozzle  10 A of the first embodiment. 
     That is, in the nozzle  10 B according to the second embodiment, the front end surface has a first surface  11 Ba positioned on the nozzle center side and a second surface  12 Ba continuing to the outer peripheral side of the first surface  11 Ba, and the first surface  11 Ba and the second surface  12 Ba formed of surfaces differing in surface free energy. Specifically, the second surface  12 Ba has a high liquid repellency than that of the first surface  11 Ba. 
     As shown in  FIG. 2 , the nozzle  10 B is configured by combination of a first dripping part  11 B and a second dripping part  12 B which are formed separately. 
     As shown in  FIG. 2( b ) , the second dripping part  12 B constitutes the main body of the nozzle  10 B, and at the center of the front end part of the second dripping part  12 B, an opening through which the first dripping part  11 B is inserted (through hole) are provided. The surface of the front end part of this second dripping part  12 B serves as the second surface  12 Ba. 
     The first dripping part  11 B is formed of a hollow cylindrical member which is inserted into and engaged with the through hole at the center of the second surface  12 Ba of the second dripping part  12 B, and the first dripping part  11 B constitutes a nozzle opening through which a liquid stored in the container main body  2  can pass and is dripped. Then, the surface of the front end part of this first dripping part  11 B forms the first surface  11 Ba. 
     As described above, in the second embodiment, the second dripping part  12 B and the first dripping part  11 B are integrated to form the nozzle  10 B. 
     The surfaces of the front end parts of the first dripping part  11 B and the second dripping part  12 B constitute a first surface  11 Ba and a second surface  12 Ba, and the first surface  11 Ba and the second surface  12 Ba having different surface free energies. 
     If the surface free energy of a solid is larger than the surface free energy of a liquid, the liquid wets easily the solid. On the contrary, if the surface free energy is smaller, the liquid hardly wet the solid, and the solid exhibits liquid repellency. 
     That is, the liquid repellency changes in accordance with the magnitude of the surface free energy of the solid. 
     Allowing the surface free energies of the first surface  11 Ba and the second surface  12 Ba to be different (imparting liquid repellency) is as described above with reference to  FIGS. 3 and 4 , and the operation principle of the liquid-repellent structure will be described later with reference to  FIGS. 7 to 10 . 
     As described above, in the nozzle  10 B according to the second embodiment, the front end part surface thereof has two types of surface configuration, i.e. the first surface  11 Ba positioned on the nozzle center side and the second surface  12 Ba continuing the outer surface side of the first surface  11 Ba. That is, the front end part surface is configured such that the first surface  11 Ba and the second surface  12 Ba have different surface free energies, i.e. the second surface  12 Ba has higher surface repellency than that of the first surface  11 Ba. 
     In the second embodiment, by using such standard of liquid repellency, regarding the two surfaces constituting the front end part surface of the nozzle  10 , i.e. the first surface  11 Ba and the second surface  12 Ba, the nozzle  10 B is constituted such that the liquid repellency of the second surface  12 Ba becomes higher than that of the first surface  11 Ba by allowing the first surface  11 Ba to be a high energy surface and the second surface  12 Ba to be a low energy surface. 
     For example, the first surface  11 Ba may be configured to satisfy θ E &lt;90° with respect to a liquid as an object and the second surface  12 Ba may be configured to satisfy θ E ≧90° with respect to a liquid as an object. 
     More specifically, in the present embodiment, the first surface  11 Ba is formed of, for example, a bulk plastic resin (having low liquid repellency) as it is, and the second surface  12 Ba is configured to be a surface having higher liquid repellency as in the case of the nozzle  10 A of the first embodiment by subjecting the surface of the front end part of the nozzle  10 B to a surface treatment (e.g. fluorination or surface roughing treatment) by a predetermined method. 
     Normally, the surface of a plastic resin that is not subjected to any surface treatment has the above-mentioned “contact angle” of θ E &lt;90° for a liquid such as an eye drop that contains a surfactant or oil, and the liquid repellency is “low” (high energy with high wettability). On the other hand, by subjecting the surface of the resin to a surface treatment such as fluorination or surface roughening, it is possible to modify the surface to have a “high” liquid repellency (low energy with low wettability) where the “contact angle” becomes θ E ≧90°. 
     By doing this, among the two surfaces constituting the front end surface of the nozzle  10 B, the liquid repellency of the first surface  11 Ba to be “low” (the surface free energy is high) and the liquid repellency of the second surface  12 Ba to be “high” (the surface free energy is low). 
     Here, as for the second surface  12 Ba of which the liquid repellency is allowed to be “high” (the surface free energy is low), as in the case of the nozzle  10 A according to the first embodiment, for the surface of the front end part of the nozzle  10 B formed of a plastic molded body formed of a non-fluorine-based resin, it can be fluorinated by incorporation of fluorine atoms. Further, the second surface  12 Ba of the nozzle  10 B thus fluorinated can be surface-roughened according to need. 
     By fluorinating and roughening the second surface  12 Ba of the front end part of the nozzle  10 B in the above-mentioned way, by increasing the liquid repellency of the first surface  11 Ba on the central side of the nozzle  10 B, when a liquid (eye drop) is poured from the container main body  2 , it is possible to induce such that liquid droplets are formed only on the first surface  11 Ba, whereby it becomes possible to prevent a poured liquid from spreading and wetting a wide range towards the second surface  12 Ba. 
     Therefore, by adjusting and setting the inner diameter of the opening of the nozzle  10 B and the surface area and shape of the first surface  11 Ba, it is possible to set the quantity of liquid dispensed from the nozzle  10 B to an arbitrarily small quantity. 
     As described above, in the nozzle  10 B according to the second embodiment, the surface of the front end part has the first surface  11 Ba positioned on the nozzle central side and the second surface  12 Ba continuing to the outer peripheral side of the first surface  11 Ba, whereby the second surface  12 Ba has higher liquid repellency than that of the first surface  11 Ba. 
     More specifically, as described above, the nozzle  10 B is composed of two members, that is, the first dripping unit  11 B and the second dripping unit  12 B, and the surface of the first dripping part  11 B is allowed to be the first surface  11 Ba, the surface of the second dripping part  12 B is allowed to be the second surface  12 Ba and only the second surface  12 Ba is subjected to a predetermined water repellency treatment, thereby to allow it to have a higher liquid repellency than that of the first surface  11 Ba. 
     By providing the second surface  12 Ba for enhancing the liquid repellency of the nozzle  10 B and the first surface  11 Ba for guiding liquid droplets to the center of the nozzle  10 B, according to the inner diameter of the opening of the nozzle  10 B and the surface area or shape of the first surface  11 Ba, a liquid in a desired quantity (e.g. 10 μl or less) can be poured and dripped stably without causing variations in dripping quantity. 
     The nozzle  10 B having the first/second surfaces  11 Ba and  12 Ba as mentioned above is protected by a cap  20  which will be described later, and breakage, deterioration or the like of the droplet processing and droplet structure of the second surface  12 Ba of the nozzle  10 B can be prevented. 
     In the nozzle  10 B according to the second embodiment as described above, similarly to the case of the first embodiment, the front end part of the nozzle  10 B may be fluorinated and surface-roughened in view of improvement in liquid repellency. 
     However, as long as the front end part of the nozzle  10 B is at least fluorinated, liquid repellency can be imparted to the nozzle  10 B made of a non-fluorine-based resin. As will be described later, the plasma treatment (see  FIG. 17 ) for fluorinating the front end surface is very strong, and fine concavities and convexities are formed on the surface of the front end part of the nozzle  10 B by the plasma treatment and the surface is roughened. 
     Therefore, with regard to the nozzle  10 B of the second embodiment, it suffices that the second surface  12 Ba be at least fluorinated, and if necessary, the surface of the front end part be further surface-roughened. 
     [Constitution of the Nozzle Surface] 
     Hereinbelow, a specific surface configuration of the nozzle  10 B according to the second embodiment mentioned above that has two-step surface structures, i.e. the first surface  11 Ba and the second surface  12 Ba, will be explained with reference to  FIGS. 5 and 6 . 
       FIG. 5  and  FIG. 6  are explanatory views that schematically show the embodiments of the first/second surfaces of the nozzle front end of the nozzle  10 B according to the second embodiment. 
     In the nozzle  10 B according to the second embodiment, as shown in  FIG. 5( a ) , when it comprises the cylindrical first dripping part  11 B and the second dripping part  12 B that is arranged on the outer periphery of the first dripping part, the front end (first surface  11 Ba) of the first dripping part  11 B can be protruded from the front end (second surface  12 Ba) of the second dripping part  12 B. 
     Due to such a configuration, the first dripping part  11 B (first surface  11 Ba) is present in a protruded manner on the outer periphery of the opening of the nozzle  10 B. Further, since the second surface  12 Ba has higher liquid repellency than that of the first surface  11 Ba, liquid droplets poured from the nozzle  10 B are formed and induced such that they are brought into a state that they do not contact the second dripping part  12 B (second surface  12 Ba) and contact only the surface (first surface  11 Ba) of the protruded surface of the first dripping part  11 B. 
     Even if the second surface  12 Ba has variations in liquid repellency, the droplets are not affected by this, and even when air entrainment occurs, the liquid droplets are not separated or dispersed on the side of the second surface  12 Ba, and they are always induced so as to be formed at the center of the opening of the nozzle  10 B. As a result, reliable and stable pouring and dripping can be conducted without causing biasing or variations in liquid droplets. 
     Further, as compared with the basic structure as described above, for example, as shown in  FIG. 5( b ) , it is possible to make the cylindrical part constituting the first dripping part  11 B (the first surface  11 Ba) thicker. 
     Due to such configuration, it is possible to make the area of the first surface  11 Ba that has low liquid repellency (having high wettability) larger, whereby liquid droplets can be induced to the center of the nozzle more reliably, and as compared with the case shown in  FIG. 5( a ) , larger droplets can be formed. 
     In this case, as shown in  FIG. 5( c ) , for example, the side surface of the first dripping part  11 B protruded from the second dripping part  12 B can be subjected to a prescribed liquid repellency treatment as in the case of the second surface  12 Ba. 
     Due to such a configuration, liquid droplets are repelled from the protruded side surface of the first dripping part  11 B, and as a result, as compared with the case shown in  FIG. 5( b ) , liquid droplets can be repelled and separated from the second surface  12 Ba further reliably, thereby allowing liquid droplets to be induced and formed on the center of the nozzle. 
     As shown in  FIG. 5( d ) , the first dripping part  11 B can be configured such that the first surface  11 Ba and the second surface  12 Ba become almost “flushed” so that it is prevented from protruding from the front end (second surface  12 Ba) of the second dripping part  12 B. 
     In this case, due to high liquid repellency of the second surface  12 Ba (low energy surface) and high wettability of the first surface  11 Ba (high energy surface), it is possible to inducibly form liquid droplets in a state that they contact only the surface part of the first dripping part  11 B (first surface  11 Ba) without moving to the second dripping part  12 B (second surface  12 Ba). 
     Further, in this case, since the first dripping part  11 B is not protruded, a spherical body of a liquid droplet is prevented from spreading widely, and as a result, as compared with a case shown in  FIG. 5( a ) , it is possible to form a smaller liquid droplet with a smaller liquid quantity. 
     Further, in  FIGS. 5( a ) and ( b ) , the cross section including the nozzle central line of the surface part of the first dripping part  11 B (first surface  11 Ba) has a rectangular shape. As shown in  FIG. 5( e ) , by allowing the front end of the first dripping part  11 B to be tapered, it is possible to allow the first surface  11 Ba to be a tapered shape that becomes narrower in the dripping direction. 
     Due to such a configuration, it is possible to allow the area of the first surface  11 Ba that is formed of the front end surface of the first dripping part  11 B to be smaller than the cases shown in  FIGS. 5( a ) and ( b ) , and by reducing the adhesiveness between the first surface  11 Ba and the liquid droplets, it is possible to allow liquid droplets formed to be smaller with a smaller liquid quantity. 
     Further, it is possible to allow the area of the first surface  11 Ba formed of the front end surface of the first dripping part  11 B to be further larger as compared with the cases shown in  FIGS. 5( a ) to ( e ) . 
     For example, as shown in  FIG. 5( f ) , by forming the front end of the first dripping part  11 B so as to spread in the form of a trumpet and by forming the first surface  11 Ba in a tapered shape enlarging in the dripping direction, the first surface  11 Ba can be made larger and wider. 
     Due to such a configuration, it is possible to make the area of the first surface  11 Ba formed by the front end surface of the first dripping part  11 B larger than that in the case of  FIGS. 5 ( a ) to ( e ) , and by increasing the adhesive power between the first surface  11 Ba and liquid droplets, it becomes possible to hold liquid droplets with a larger liquid quantity and a larger spherical shape, and as a result, it becomes possible to form larger droplets having a larger liquid quantity. 
     Further, the first/second surfaces  11 Ba and  12  Ba as described above are constituted by two separate parts of the first/second dripping parts  11 B and  12 B, for example. Other than this, as shown in  FIG. 5( g )  it is also possible to form the first surface  11 Ba projecting into the nozzle together with the second surface  12 Ba at the front end part of the second dripping part  12 B. 
     The first surface  11 Ba that integrally protrudes from the front end opening of the second dripping part  12 B can be formed of burrs that are naturally formed when an opening (through hole) is bored in the second dripping part  12 B by means of a drill or the like (see  FIG. 4( d ) ), or can be formed by injection molding. 
     In this case, after the first surface  11 Ba is projectingly formed at the front end part of the second dripping part  12 B, in a state where the first surface  11 Ba is protected by coating, etc., the front end part of the second dripping part  12 B is subjected to a fluorination and surface-roughing treatment mentioned later, whereby the second surface  12 Ba can be formed. 
     Due to such a configuration, not only for a case where the first surface  11 Ba is projectingly formed on the front end part of the second dripping part  12 B, but also for a case where the first surface  11 Ba is not protruded from the second surface  12 Ba as shown in  FIG. 5( d ) , it is possible to form the first/second surfaces  11 Ba and  12 Ba integrally in the second dripping part  12 B. 
     By integrally forming the first/second surfaces  11 Ba and  12 Ba by using the same parts, it is possible to reduce the number of components or simplify the production process. 
     Further, when the first dripping part  11 B and the second dripping part  12 B are formed of separate parts, not only the first dripping part  11 B has a tubular body as shown in  FIGS. 5( a )  to  5  ( g ), but also, as shown in  FIG. 5( h ) , for example, it is also possible to use a means with which a liquid is dripped utilizing a capillary phenomenon with a fiber member, a nonwoven fabric, etc. as the first dripping part  11 B. 
     As mentioned above, the first dripping part  11 B that constitutes the nozzle  10  according to this embodiment is not limited to a cylindrical body or a tubular body as long as it is capable of dripping from the front end part of the nozzle a prescribed quantity of a liquid in the container main body  2 . 
     Further, as shown in  FIG. 6 ( a ) , the first dripping part  11 B is prevented from protruding from the front end (the second surface  12  Ba) of the second dripping part  12 B, and the first surface  11 Ba is formed to have a “chamfered” shape in which it is recessed in a tapered manner inwardly to the second surface  12 Ba. This configuration can be formed by inserting the first dripping part  11 B of which the inner surface of the end part is chamfered in a tapered way into the second dripping part  12 B that forms the second surface  12 Ba. 
     Even in this case, liquid droplets poured from the nozzle  10  do not contact the second dripping part  12 B (the second surface  12 Ba), and are brought into a state that they contact only the surface of the first dripping part  11 B (first surface  11 Ba) that is recessed in a tapered manner, whereby liquid droplets can be induced to the center of the opening of the nozzle  10 , and reliable pouring and dripping can be conducted. 
     Further, when the first surface  11 Ba is formed into a chamfered shape that tapers inwardly to the second surface  12 Ba as mentioned above, as shown in  FIG. 6( b ) , the first surface  11 Ba having a chamfered shape can be integrally formed with the second surface  12 Ba at the front end part of the second dripping part  12 B. 
     By doing so, it is possible to form the first/second surfaces  11 Ba,  12 Ba only with the second dripping part  12 B, and as a result, it is possible to reduce the number of parts and to simplify the manufacturing process, etc. In particular, the step of inserting the first dripping part  11 B and the step of aligning the first/second surfaces  11 Ba,  12 Ba become unnecessary, and the first surface  11 Ba can be formed by only chamfering the inner surface of the end part of the opening for the second dripping part  12 B in which the second surface  12 Ba is formed in advance, whereby the production process can be significantly simplified and facilitated. 
     [Operation Principle of Liquid-Repellency Structure] 
     Next, liquid-repellency structure by fluorination and surface roughing provided on the surface of the front surface of the nozzle  10  according to one or more embodiments of the present invention (the surface of the front end part  11 A of the nozzle  10 A of the first embodiment and the second surface  12 Ba of the nozzle  10 B of the second embodiment) and its operation principle will be explained with reference to  FIGS. 7 to 10 . 
     Here, in order to improve the liquid repellency to the liquid, it is generally conceivable to use a fluorine-containing resin such as polytetrafluoroethylene (PTFE) as the plastic. However, the contact angle of PTFE to water is at most about 115°, and does not exhibit liquid repellency for a liquid containing a substance having a low surface tension such as alcohol or oil. In addition, since the fluorine-containing resin is very expensive and difficult to mold, the application thereof, etc. are extremely limited. 
     For this reason, it is a subject to improve the liquid repellency of a plastic molded body formed by using a fluorine-free non-fluorine-based resin such as polyolefin or polyester. 
     As means for enhancing the liquid repellency of the liquid, means for providing a liquid-repellent film on the surface of the nozzle or the like or means for forming concavities and convexities can be considered. 
     For example, by providing a liquid repellent thin film different from the base material (for example, a film containing a compound or resin containing fluorine, silicon or the like) on the surface, it is possible to improve liquid repellency. However, according to such a method, adhesion to the base material tends to be insufficient, and when the dripping is repeatedly performed, the liquid-repellent thin film or the like is peeled off and falls off, not only the liquid repellency is lost, but also there is a risk that the content liquid is contaminated. 
     On the other hand, means for providing concavities and convexities on the surface of a nozzle or the like physically imparts liquid repellency by the surface shape. 
     That is, when a liquid flows on the concavo-convex surface formed on the surface of the nozzle, etc., an air pocket is formed in the concave parts, the contact state between the concavo-convex surface and the liquid becomes a mixed contact state of solid-liquid contact and air-liquid contact. In addition, a gas (air) is a substance having highest liquid repellency. Therefore, by appropriately setting the roughness and denseness of the concavities and convexities, a significantly high liquid repellency can be realized. 
     However, care should be taken that a liquid is repeatedly flown on the concavo-convex surface, a liquid is gradually stored in the concave part, and the function of the air pocket is gradually lost, and water repellency is gradually lowered. 
     In one or more embodiments of the present invention, first, fluorine atoms are incorporated into a molecular chain of a non-fluorine-based resin of a plastic molded body that constitutes the surface of the nozzle  10  (the front end part  11 A of the nozzle  10 A of the first embodiment and the second dripping part  12 B of the nozzle  10 B of the second embodiment). 
     In addition, the surface of the front end part of the nozzle  10  thus fluorinated (the surface of the front end part  11 A of the first embodiment and the second surface  12 Ba of the second embodiment) is surface-roughed to further form concavo-convex part. 
     In the nozzle  10 B of the second embodiment, the first surface  11 Ba having lower liquid repellency than that of the second surface  12 Ba is disposed at the center of the roughened nozzle surface. Specifically, in the center of the opening of the second dripping part  12  that is subjected to a liquid-repellent treatment, a tubular and cylindrical first dripping part  11  is inserted and fitted. 
     In the nozzle  10 A of the first embodiment, as part of the surface roughed structure, a circumferential protruded part  13  that protrudes from the front end surface (see  FIG. 4( d ) ) can be provided on the outer periphery of the surface-roughened opening  11   a  of the nozzle  10 . 
     By increasing the liquid repellency of the nozzle  10  in this way, a desired dripping quantity (e.g. 10 μl or less) of a liquid can be poured and dropped in accordance with the inner diameter of the opening of the front end part of the nozzle  10 . 
     Further, the nozzle  10  that is subjected to a liquid-repellency treatment in this way is protected by a cap  20  mentioned later, whereby breakage, deterioration or the like of the surface-surface-roughened structure at the front end part of the nozzle  10  are prevented from occurring. 
       FIG. 7  shows a morphology of a roughened surface formed on the surface of the front end part in a plastic molded body constituting the nozzle  10  according one or more embodiments of the present invention (the front end part  11 A of the nozzle  10 A of the first embodiment and the second dripping part  12 B of the nozzle  10 B of the second embodiment  10 B). 
     In this figure, the surface of the front end part is formed of a non-fluorine-based resin. In this surface, a roughened surface  100  formed of minute concavities and convexities is formed (in  FIG. 7 , the top of the convex part in the roughened surface  100  is denoted by S). 
     Fluorine atoms are incorporated into a molecular chain of the non-fluorine-based resin forming this roughened surface  100  by a post-treatment. For example, when the molecular chain of the non-fluorine-based resin is represented by —(CH 2 ) n —, a fluorine atom is incorporated in a part of this molecular chain to form a fluorine-containing moiety such as —CHF— or —CF 2 —. Such post-processing for incorporating fluorine atoms can be performed by fluorine plasma etching described later (see  FIG. 17 ). 
     The liquid repellency on the roughened surface  100  mentioned later will be explained with reference to  FIG. 8 . 
     As shown in  FIG. 8( a ) , with respect to the contact pattern of the liquid droplet on the roughened surface  100  as described above, in the Cassie mode in which droplets are placed on the roughened surface  100 , the concave part in the roughened surface  100  is an air pocket, and the droplets are brought into a state of composite contact of a solid and a gas (air). In such composite contact, the contact radius R at the contact interface of droplets is small, the adhesiveness between liquid droplets and the roughened surface is low, and hence the liquid comes in contact with the air with the highest liquid repellency, whereby high liquid repellency is exhibited. The contact angle of the roughened surface  100  in such Cassie mode is represented by the following theoretical formula (1): 
     
       
         
           
             
               
                 
                   
                     
                       
                         
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                          
                         
                           
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                               ϕ 
                               S 
                             
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     θ E : Contact angle 
     θ*: Apparent contact angle 
     φ S : Area ratio (projection area of the solid-liquid interface per unit area) 
     As can be understood from this theoretical formula (1), as φ S  gets small, the apparent contact angle θ* gets closer to 180°, whereby ultrahigh liquid repellency is exhibited. 
     On the other hand, if liquid droplets enter the recess of the roughened surface  100 , the liquid droplets are brought into contact only with a solid, not in the above-mentioned composite contact, and is shown by the Wenzel mode. In such Wenzel mode, the contact angle R in the contact interface of the liquid droplets is large, and adhesion power between the liquid droplets and the roughened surface is high. The contact angle of the concavo-convex surface is represented by the following theoretical formula (2): 
       cos θ*= r  cos θ E   (2)
 
     θ E : Contact angle 
     θ*: Apparent contact angle 
     r: Concavo-convex degree (=actual contact angle/projected area of liquid droplets) 
     As can be understood from this theoretical formula (2), the larger r, the closer the apparent contact angle θ* to 180°, whereby ultrahigh liquid repellency is exhibited. 
     As for the liquid repellency, as mentioned above, it is known that liquid repellency is improved in either the Wenzel mode or the Cassie mode. In order to reduce the adhesiveness between the roughened surface  100  and the liquid droplets to allow small quantity of liquid droplets to drip, it is required to maintain stably the Cassie mode, not the Wenzel mode, i.e. the air pocket of the concave part is stably maintained. 
     That is, in the Wenzel mode, the interface between the liquid phase and the solid phase is large, and as a result, the physical adsorption force acting on the interface is also increased, whereby the contact angle is large and the liquid repellency is achieved, and hence, liquid droplets do not drip or fall easily. 
     On the other hand, in the Cassie mode, since the interface is small, the adhesiveness which is required to be overcome when liquid droplets drop, the liquid droplets can drip and fall easily, and it is considered that the liquid droplets drop repeatedly many times. 
     Therefore, in the present embodiment, in order to effectively maintain the contact of the droplets in the above-described Cassie mode, by incorporating fluorine atoms into a molecular chain of the non-fluorine-based resin forming the roughened surface  100  of the front end part of the nozzle  10 , liquid repellency is chemically imparted. 
     That is, if the liquid enters the concave part in the roughened surface  100 , the contact pattern of the liquid droplets becomes the Wenzel mode, and as a result, the ultrahigh liquid repellency by the Cassie mode is impaired. In the present embodiment, by incorporating fluorine atoms into a molecular chain of the non-fluorine-containing resin forming the roughened surface  100 , it is possible to chemically impart liquid repellency to the rough surface  100 , the ultrahigh liquid repellency by the Cassie mode can be stably maintained. 
     In particular, in the present embodiment, at least part of the roughened surface  100  (e.g. at the top of the convex part or at the bottom of the concave part), a fluorine atom is incorporated in a molecular chain of the non-fluorine-based resin forming this surface in order to exhibit chemical liquid repellency. Therefore, even when the liquid is repeatedly brought into contact with the roughened surface  100 , this fluorine atom is not removed, the chemical liquid repellency is stably maintained, and as a result, the ultrahigh liquid repellency in the Cassie mode is not lowered and is maintained at a level as high as that in the initial stage. 
     Furthermore, instead of forming a film containing fluorine atoms, fluorine atoms may be incorporated in a molecular chain of the non-fluorine-based resin on the surface, so that peeling off or falling off of the fluorine film does not occur at all. 
     Here, as for the concavo-convex degree of the roughened surface  100  as described above, in order to allow the liquid repellency to be fully exhibited by the Cassie mode, the area ratio φs, that is expressed by the area of the top of the convex part S per unit area in the roughened surface  100 , may be 0.05 or more, or 0.08 or more. 
     Further, in respect of moldability or mechanical strength, the area ratio D may be 0.8 or less, or 0.5 or less. 
     Further, the depth d in the roughened surface  100  may be 5 to 200 μm, in particularly 10 to 50 μm. 
     Regarding the roughened surface  100 , a concavo-convex structure shown in  FIG. 9  can be taken. 
     That is, liquid droplets having a surface tension γ and an initial contact angle θ is, as shown by the following formula (3), supported by the Laplace pressure (Δp) represented by the concavo-convex apex angle α and the ½ pitch R 0  of the concavities and convexities to form an air pocket. That is, when the concavo-convex apex angle α becomes smaller, the ½ pitch R 0  becomes smaller, and the concavo-convex structure becomes a pen tip shape, the Laplace pressure becomes larger, whereby liquid droplets hardly enter the concavities and convexities, whereby the liquid repellency is exhibited. 
     Therefore, as shown in  FIG. 9 , the larger the arithmetic average roughness Ra representing the amplitude of the concavo-convex structure and the smaller the average length RSm corresponding to the ½ pitch R 0 , the Laplace pressure is large and the liquid repellency is exhibited. Therefore, Ra/RSm may be 50×10 −3  or more, or 200×10 −3  or more. 
       Δ p =−γ cos(θ−α)/( R   0   +h  cos α)  (3)
 
     In addition, in the present embodiment, formation of the roughened surface  100  composed of the minute concavities and convexities as described above can be generally easily formed by a transfer method using a metal stamper. For example, by a resist method or the like, by heating a stamper having a roughened surface part corresponding to the above-described minute concavities and convexities to an appropriate temperature and pressing it against a predetermined part of the surface of the plastic molded body to transfer the roughened surface part, the roughened surface  100  can be formed on the surface of the front end part of the nozzle  10  made of a plastic molded body. Therefore, the concavo-convex surface of the stamper is formed on the surface of the front part of the nozzle  10  in a state that the concavities and convexities are reversed. 
     Further, by the roughening treatment by using such a stamper, a thick wall part  15  described later can be formed simultaneously at the outer periphery of the front end part of the nozzle  10  (see  FIGS. 21 to 26 ). 
     In the present embodiment, the roughened surface formed at the front end part of the nozzle  10  is not limited to the concavities and convexities of the roughened surface  100  shown in  FIG. 7 or 9 . From the viewpoint of stably forming an air pocket, the convex part and the concave part as shown in  FIG. 7  may be formed in a rectangular shape. For example, when the concave part has a V-shaped configuration, the liquid droplet easily enters the concave part. 
     Incorporation of the non-fluorine-based resin forming the surface of the nozzle  10  into a molecular chain can be carried out by etching using fluorine plasma. 
     Here, the fluorine plasma etching can be conducted by using a known method (see  FIG. 17  to be described later). For example, by using a CF 4  gas, a SiF 4  gas or the like to dispose the surface of a plastic molded body forming the roughened surface  100  between a pair of electrodes and applying a high-frequency electric field, plasma of fluorine atoms (atomic fluorine) is generated. By allowing the thus generated plasma to collide with a part forming the roughened surface  100 , fluorine atoms are incorporated into a molecular chain of the non-fluorine-based resin forming the surface (roughened surface  100 ). That is, the resin on the surface is gasified or decomposed, and fluorine atoms are incorporated simultaneously. 
     Accordingly, ultrafine concavities and convexities are formed in a region where fluorine atoms are incorporated by etching. The arithmetic average surface roughness in these ultrafine concavities and convexities is generally 100 nm or less, and Ra/RSm≧× 10   −3 . 
     Further, the conditions such as the applied high-frequency voltage and the etching time can be set to appropriate ranges according to the roughness (area ratio φs) of the roughened surface  100 . 
     For example, the conditions may be those under which, when the dripped quantity is measured after liquid droplets (eye drop) are repeatedly dripped 100 times in a dripping resistant test to make the front end of the nozzle contaminated, performance of dripped quantity≦10 μL is exhibited. Such conditions may be set in advance by a laboratory test, etc. 
     Generally, when the element ratio (F/C) of fluorine atoms and carbon per unit area is 40% or more, particularly 50 to 300%, the surface strength is impaired, although it depends on the roughness of the roughened surface  100 . In addition, it is possible to ensure stable ultrahigh liquid repellency as described above. The element ratio can be calculated by analyzing the elemental composition on the surface using an X-ray photoelectron spectroscope. 
     Further, in the present embodiment, the roughened surface  100  formed at the front end part of the nozzle  10  is not limited to the embodiment shown in  FIG. 7  or  FIG. 9  described above. For example, as shown in  FIG. 10 , the roughened surface  100  can be formed by a fractal hierarchy structure. 
     Specifically, as shown in  FIG. 10 , it is possible to form fine secondary concavities and convexities on the primary concavities and convexities  160  formed by relatively large convex parts  160   a  and concave parts  160   b . In this way, since a droplet  170  is placed on the secondary concavities and convexities, an air pocket (secondary air pocket) is also formed between the liquid droplet  170  and the secondary concavities and convexities. The secondary air pocket between the liquid droplet  170  and the secondary concavities and convexities prevents the entry of the liquid droplet  170  into the concave part  160   b  of the primary concavities and convexities  160  and it is possible to more effectively prevent the disappearance of the air pocket formed the primary concavities and convexities  160  and the liquid droplet  170 . As a result, the state in the Cassie mode can be maintained more stably, whereby liquid repellency can be maintained more stably. 
     In the roughened surface  100  having the hierarchical structure as described above, the secondary concavities and convexities on the surface part of the primary concavities and convexities  160  have a surface roughness that is enough to allow formation of a secondary air pocket that prevents the liquid droplets on the secondary concavo-convex from entering the concave part  160   b  of the primary concavities and convexities  160 . For example, the ratio of the arithmetic average roughness to the average length, Ra/RSm, may be 50×10 −  or more, or 200×10 −3  or more. 
     Further, as the primary concavities and convexities  160 , it suffices that they may have the same area ratio φ and the depth d of the concavities and convexities as those of the roughened surface  100  having a morphology shown in  FIG. 7 . As a result, liquid repellency by the Cassie mode can be fully exhibited. 
     The secondary concavities and convexities may be formed on the entire surface of the primary concavities and convexities  160  from the viewpoint of more effectively preventing the liquid droplet  170  from entering the concave part  160   b  of the primary concavities and convexities  160 . However, it suffices that they are formed at least at the upper end of the convex part  160   a  of the primary concavities and convexities  160 . 
     The roughened surface  100  having a hierarchical structure as described above can be formed by a method in which minute secondary concavities and convexities are formed on an uneven surface for forming primary concavities and convexities by blasting, etching, etc. and transfer is conducted by using such stamper. 
     In the present embodiment, in at least part of the primary concavities and convexities  160  on which the secondary concavities and convexities are formed as mentioned above (in particular, a part that forms a top of the convex part  160   a  or a part that forms a bottom of the concave part  160   b  of the primary concavities and convexities  160 ), a fluorine atom is incorporated into a molecular chain of the non-fluorine-based resin forming the surface by plasma etching. In such a region, by etching when a fluorine atom is incorporated, third concavities and convexities that are obtained by further miniaturizing the secondary concavities and convexities are formed. The arithmetic average roughness Ra of the third concavities and convexities is generally 100 nm or less, and Ra satisfies Ra/RSm≧5×10 −3 , as in the case of the ultrafine concavities and convexities formed by etching mentioned later. 
     The nozzle  10  according to the present embodiment is formed by using a non-fluorine-based resin. As such a non-fluorine-based resin, i.e. a resin containing no fluorine, any thermoplastic resin, thermosetting resin, photocurable resin, etc. can be given as long as it can form the above-mentioned the roughened surface  100  formed of concavities and convexities and can permit incorporation of a fluorine atom into a molecular chain by fluorine plasma etching. An appropriate resin may be selected according to molding conditions, etc. of the nozzle  10 . It may be of a multilayer structure. 
     In general, in the field of liquid containers, olefinic resins typified by polyethylene, polypropylene, copolymers of ethylene or propylene and other olefins, polyesters such as polyethylene terephthalate (PET), polyethylene isophthalate, polyethylene naphthalate and the like are representative as a resin for surface forming. 
     The nozzle  10  according to the present embodiment as described above can be applied as a nozzle/pouring means of various containers by taking advantage of the long life and excellent liquid repellency of the roughened surface  100 . In particular, since falling property and drainability of the liquid is excellent, liquid dripping and presence of residual liquid on the nozzle top surface can be suppressed, it can be effectively used as a nozzle for a container or a wrapping body accommodating various liquid medicine such as the container  1  for instillation of eye drops. 
     [Cap] 
     In the container main body  2  including the nozzle  10  that is subjected to a liquid-repellent treatment, a cap  20  is detachably attached. By the cap  20 , the nozzle  10  is covered, whereby the inside of the container main body  2  is sealed, and the front end part of the nozzle  10  is protected. 
       FIGS. 11 and 12  are views showing the cap  20  that covers the nozzle  10 A according to the first embodiment, and  FIGS. 13 to 15  are views showing the cap  20  that covers the nozzle  10 B according to the second embodiment. 
     As shown in these figures, the cap  20  is formed of a bottomed cylindrical body that can be attached such that it covers the protruded part of the container main body  2  including the nozzle  10 . At the bottom surface of the cylindrical body, a liner  21  for sealing is provided such that it contacts the nozzle  10 . 
     In the cap  20  corresponding to the nozzle  10 A of the first embodiment, as shown in  FIGS. 11 and 12 , the liner  21  contacts a side surface  12 A of a nozzle  10 A. 
     In the cap  20  corresponding to the nozzle  10 B of the second embodiment, as shown in  FIGS. 13 and 14 , the liner  21  contacts the front end surface (first surface  11 Ba) of the first dripping part  11 B and the side surface part of the second dripping part  12 B. 
     Due to contact or pressure welding of the liner  21  with the front end surface of the side surface part or the front end surface of the first dripping part  11 B of the nozzle  10 , the nozzle  10  and the container main body  2  are shielded and sealed from the outside, whereby a liquid (eye drop) stored in the container main body  2  is prevented from leaking outside. 
     On the inner side surface of the cap  20 , there is provided a screw structure screwed together with the surface of the projected part of the container main body  2  to which the nozzle  10  is attached. As a result, the cap  20  is detachably attached to the container main body  2  by screwing, and in a state where the cap  20  is attached, the liner  21  is brought into close contact with the side surface part or the front end surface of the first dripping part  11 B of the nozzle  10 , whereby the inside of the container is sealed. 
     Here, the cap  20  is formed of a plastic material like the container main body  2  and the nozzle  10 . The plastic material forming the cap  20  is not particularly limited, and the cap  20  can be formed by using various thermoplastic resins, e.g. olefinic resins such as polyethylene and polypropylene, or polyester resins represented by polyethylene terephthalate (PET) as in the case of the container main body  2  and the nozzle  10 . 
     In addition, the liner  21  provided on the inner surface of the cap  20  can be formed of a known elastic material, for example, a thermoplastic elastomer such as an ethylene-propylene copolymer elastomer or a styrene elastomer. 
     Further, the cap  20  can be made of glass or a metal in addition to a plastic material. The cap  20  may be integrally formed with the container main body  2  through a hinge, etc. 
     The cap  20  according to the present embodiment is configured to cover the protruded part of the container main body  2  including the nozzle  10  without contacting the front end part of the nozzle  10 . 
     The cap  20  is configured so as to cover the protruded part of the container main body  2  including the nozzle  10  in such a manner that, in the cap  20  corresponding to the nozzle  10 A according to the first embodiment, the inner surface of the cap  20  including the above-described liner  21  does not contact the front end part  11  of the nozzle  10 A, and in the cap  20  corresponding to the nozzle  10 B according to the second embodiment, the inner surface of the cap  20  including the liner  21  does not contact the front end surface (the second surface  12 Ba) of the second dripping part  12 B. 
     Due to such a configuration, the nozzle  10  can be protected by the cap  20  without contact of the cap  20  with the front end part of the nozzle  10  that is fluorinated and surface-roughened as mentioned above, whereby the liquid-repellent performance and liquid-repellent structure of the front end surface of the nozzle  10  are not deteriorated. 
     Specifically, as shown in  FIGS. 1 and 2 , in the nozzle  10  according to the present embodiment, the front end part  11 A and the second dripping part  12 B are formed such that the side surface parts  12 A and  12 Bb are inclined such that it is tapered towards the front end part. 
     As shown in  FIGS. 11 to 14 , the liner  21  provided on the inner surface of the cap  20  is formed in a mortar shape corresponding to the tapered shape of the side surfaces  12 A and  12 Bb of the nozzle  10 . Due to such a configuration, in the cap  20 , the liner  21  contacts the side surfaces  12 A and  12 Bb of the nozzle  10 , and any part of the cap  20  does not contact the front end part. 
     As a result, as the liner  21  contacts and is pressed against the side surface side of the nozzle  10 , the cap  20  can seal the container main body  2 , and the liquid-repellent structure at the front end part of the nozzle  10  is protected without contacting any part. 
     In the cap  20  corresponding to the nozzle  10 A of the first embodiment shown in  FIG. 11 , in a state that the liner  21  contacts the side surface part  12  of the nozzle  10  attached to the container main body  2 , an opening  11   a  of the front end part  11  of the nozzle  10  is kept open. In this state, the opening  11   a  is shielded and sealed from the outside by the liner  21 , and hence, the liquid is not leaked outside the cap  20  from the opening  11   a.    
     In the cap  20  corresponding to the nozzle  10 B of the second embodiment shown in  FIG. 13 , in a state that the liner  21  contacts the front end part  11  (first surface  11 Ba) of the first dripping part of the nozzle  10  attached to the container main body  2 , the opening of the nozzle  10  (first dripping part  11 ) is closed and sealed in a state that it is intercommunicated with the container main body  2 . In this state, the opening is sealed by the liner  21 , the liquid is not leaked to the outside of the cap  20  from the opening. 
     In these cases, if the inner diameter of the opening of the nozzle is reduced, the pressure loss increases. Therefore, the liquid never seep out from the opening to the inner surface of the liner  21  of the cap  20  only by the discharge pressure caused by the own weight of the content liquid. However, if the container  1  is crushed by any external force and the inner pressure is increased, the content liquid may seep out. 
     In this case, the liquid seeped out to the front end part of the nozzle  10  may adhere to the surface of the front end part  11 A or the first/second surfaces  11   a  and  12   a . In such a case, adhered liquid may effect adversely when original dripping operation is conducted. 
     Under such circumstances, the cap  20  can be configured to prevent the liquid from seeping out from the nozzle opening. 
     For example, as shown in  FIG. 12 or 14 , the cap  20  is configured to close the front end of the nozzle  10  by pressing the side surface parts  12 A and  12 Bb continuing from the front end part of the nozzle  10  by the liner  21  arranged on the inner surface of the cap  20 . 
     Specifically, in the cap  20  shown in  FIGS. 12 and 14 , the liner  21  that is in contact with the side surface parts  12 A,  12 Bb of the nozzle  10  is formed into a mortar shape being inclined more acutely than the tapered shape of the side surface parts  12 A,  12 Bb, and the side surface parts  12 A and  12 Bb of the nozzle  10  that are in contact with the liner  21  are pressed towards the center of the nozzle. As a result, due to elasticity of the plastic molded body, the nozzle  10  is deformed towards the inside of the nozzle, whereby the opening (opening  11   a  or the opening of the first dripping part  11 ) is closed or blocked. 
     As a result, in a state where the cap  20  is attached, the opening of the nozzle  10  is closed, and the liquid in the container main body  2  does not seep out from the opening. The cap  20  may be engaged with and connected to the container main body  2  through a hinge, etc. so that it is not separated from the container main body  2 . 
     In the cap  20  corresponding to the nozzle  10 B according to the second embodiment, as shown in  FIG. 15 , for the nozzle  10 B in which the first surface  11 Ba shown in  FIGS. 6( a ) and ( b )  mentioned above is configured in a chamfered shape that is recessed inwardly to the second surface  12 Ba in a tapered shape, a needle valve  22  that contacts and is engaged with the tapered chamfered concave part is provided, thereby to close the opening of the nozzle  10 . 
     Due to such configuration, the container main body  2  can be sealed and closed reliably by the needle valve  22  that fits the tapered chamfered concave part without contacting the liquid-repellent treated surface of the front end part of the nozzle  10 . 
     [Method for Producing Nozzle] 
     A method of producing the nozzle  10  according to the present embodiment in which the surface of the front end part is fluorinated and roughened as described above will be explained with reference to  FIGS. 16 to 19 . 
     [Nozzle  10 A of the First Embodiment] 
       FIG. 16  is an explanatory view schematically showing the method for producing a nozzle  10 A according to one or more embodiments of the present invention, in which (a) is a case where common injection molding is used, and (b) is a case where injection compression molding or heat &amp; cool type injection molding is used. 
       FIG. 17  is an explanatory view schematically showing the method for fluorine plasma etching for roughening the front end part of the nozzle  10  according to one or more embodiments of the present invention. 
     As shown in  FIG. 16( a ) , as for the nozzle  10 A according to the first embodiment, a nozzle  10  of which the front end part  11  is not fluorinated and roughened can be formed by injection molding, for example. 
     In this case, as shown in  FIG. 16( a ) ( 1 ), the nozzle  10 A can be formed by filling, solidifying, mold-releasing and removing a prescribed molten plastic resin by using a mold for injection molding. 
     Here, the nozzle  10 A can be formed in a predetermined shape and size according to the size and shape of the mold, and the inner diameter of the opening  11   a  of the nozzle  10 A can be set to a desired size, for example, 0.5 mm or less (0.1 mm, 0.2 mm, 0.4 mm, etc.). 
     Thereafter, as shown in  FIG. 16( a ) ( 2 ), prescribed concavities and convexities can be formed by pressing a prescribed stamper against the surface of the front end part  11 A of the nozzle  10 A. 
     Further, as shown in  FIG. 16( a ) ( 3 ), plasma etching is conducted for the surface of the front end part  11 A of the nozzle  10 A. 
     The fluorine plasma etching shown in  FIG. 16( a ) ( 3 ) is conducted by a method shown in  FIG. 17 , for example. That is, one electrode  200  is fixed to the front end part  11 A of the nozzle  10 A and the other electrode  201  is opposed such that the front end part  11  is placed therebetween, and a high-frequency electric field is applied while flowing a fluorine-containing gas between these electrodes. 
     By the methods mentioned above, the roughened surface  100  shown in  FIGS. 7 to 10  mentioned above can be formed and the front end part  11  of the nozzle  10  can be fluorinated and roughened. 
     As a result, the nozzle  10 A according to one or more embodiments of the present invention is completed. 
     Further, by using special injection compression molding or heat &amp; cool type injection molding instead of common injection molding as shown in  FIG. 16( a ) , the nozzle  10  having predetermined concavities and convexities on the surface of the front end part  11  can be formed by integral molding. 
     By using special injection compression molding or heat &amp; cool type injection molding technology, it becomes possible to subject to a desired part of a molded article to fine concavities and convexities-forming treatment and surface roughening treatment in the molding step. As shown in  FIG. 16( b ) ( 1 ), the molding step of the nozzle  10 A and the surface roughing of the front end part  11 A can be conducted as a single step. That is, as shown in  FIG. 16( b ) ( 2 ), the concavities and convexities-forming treatment and surface roughening treatment by using a stamper, etc. shown in  FIG. 16( a ) ( 2 ) can be omitted. 
     Thereafter, as shown in  FIG. 16( b ) ( 3 ), by conducting fluorine plasma etching for the surface of the front end part  11  of the nozzle  10  (see  FIG. 17 ), the fluorinating and surface-roughening treatment are completed. 
     [Nozzle  10 B of the Second Embodiment] 
       FIG. 18  is an explanatory view schematically showing the method for producing the nozzle  10 B according to one or more embodiments of the present invention, in which (a) is a case where common injection molding is used; and (b) is a case where injection compression molding or heat &amp; cool type injection molding is used. 
       FIG. 19  is an explanatory view schematically showing the method for producing the nozzle shown in  FIG. 18( a ) , showing a case where, in the production method shown in  FIG. 18( a ) , a first surface  11 Ba with a chamfered shape is formed on the front end opening of the second dripping part  12 B without using the first dripping part  11 B. 
     The method for producing the nozzle  10 B according to the second embodiment shown in these figures are basically almost the same as the method for producing the nozzle  10 A of the first embodiment mentioned above ( FIGS. 16 and 17 ). 
     However, in the case of the nozzle  10 B according to the second embodiment, the second dripping part  12 B constituting the nozzle main body and the first dripping part  11 B inserted into and engaged with the front end of the second dripping part  12 B are separately configured, and hence they are separately produced. 
     The second dripping part  12 B that constitutes the nozzle main body can be produced by the same production method as that of the nozzle  10 A of the first embodiment mentioned above. 
     That is, as shown in  FIG. 18 ( a ) , with respect to the second dripping part  12 B, first, a second dripping part  12  of which the surface of the front end part is not fluorinated and roughened is formed by injection molding, for example. In this case, as shown in  FIG. 18( a ) ( 1 ), the second dripping part  12 B can be formed by filling, solidifying, mold-releasing and removing a prescribed molten plastic resin by using a mold for injection molding. 
     In accordance with the dimension or shape of the mold, the nozzle  10 B (the second dripping part  12 B) can be formed into a prescribed shape and to have a prescribed dimension. The nozzle  10 B can be formed to have an inner diameter that allows the first dripping part  11 B serving as the final opening of the nozzle  10 B to be inserted and engaged. Specifically, the nozzle  10 B can be formed such that it has an outer diameter that is almost similar to or slightly larger than the outer diameter of the first dripping part  11 B. 
     Further, although not particularly shown, the first dripping part  11 B can be produced in a prescribed shape with a prescribed dimension by using injection molding, for example, as in the case of the production of the second dripping part  12 B. 
     Since the opening (inner diameter) of the first dripping part  11 B serves as the final opening of the nozzle  10 B, it is possible to set the inner diameter thereof into a desired size, for example, 0.5 mm or less (0.1 mm, 0.2 mm, 0.4 mm, etc.). 
     Thereafter, as shown in  FIG. 18( a ) ( 2 ), by pressing a prescribed stamper against the front end part surface of the second dripping part  12 B to form prescribed concavities and convexities, whereby the highly liquid-repellent second surface  12 Ba (low energy surface) can be formed. 
     Further, as shown in  FIG. 18( a ) ( 3 ), fluorine plasma etching is conducted for this second surface  12 Ba. 
     The fluorine plasma etching shown in  FIG. 18 ( a ) ( 3 ) is performed in the same manner as in the case of the nozzle  10 A of the first embodiment described above. For example, by using the method shown in  FIG. 17 , one electrode  200  is fixed in the vicinity of the front end part of the second dripping part  12 B, and the other electrode  201  is placed such that it opposes to the electrode  200  so that the surface of the front end part (second surface  12 Ba) is arranged therebetween, and a high-frequency electric field is applied while flowing a fluorine-containing gas between these electrodes. 
     By the above procedures, the roughened surface  100  shown in  FIGS. 7 to 10  mentioned above can be formed, and the front end part of the second dripping part  12 B (second surface  12 Ba) serving as the main body of the nozzle  10 B can be fluorinated and roughened. 
     Thereafter, as shown in  FIG. 18( a ) ( 4 ), into a through hole at the center of the front end part of the second dripping part  12 B that is fluorinated and roughened, the first dripping part  11 B produced in a separate step can be inserted and engaged. 
     As a result, the nozzle  10 B according to the second embodiment is completed. 
     Further, as for the nozzle  10 B according to the second embodiment, as in the case of the nozzle  10 A of the first embodiment, by using special injection compression molding or heat &amp; cool type injection molding instead of common injection molding as shown in  FIG. 18( a ) , the second dripping part  12  provided with prescribed concavities and convexities on the front end part surface can be formed by integral molding. 
     By using special injection compression molding or heat &amp; cool type injection molding technology, it becomes possible to subject to a desired part of a molded article to fine concavities and convexities-forming treatment and surface roughening treatment in the molding step. As shown in  FIG. 18( b ) ( 1 ), the molding step of the second dripping part  12 B and the surface roughing of the front end part (forming step of second surface  12 Ba) can be conducted as a single step, and one step can be omitted. That is, as shown in  FIG. 18( b ) ( 2 ), the concavities and convexities-forming treatment and surface roughening treatment by using a stamper, etc. shown in  FIG. 18( a ) ( 2 ) can be omitted. 
     Thereafter, as shown in  FIGS. 18( b ) ( 3 ) and ( 4 ), by conducting a fluorinating and surface-roughening treatment for the surface of the front end part of the nozzle  10 B by plasma etching (see  FIG. 17 ), and by allowing the first dripping part  11 B produced in a separate step to be inserted and engaged with the second dripping part  12 B, the nozzle  10 B is completed. 
     Regarding the nozzle  10 B according to the second embodiment, as shown in  FIG. 19 , when a first chamfered first surface  11 Ba is formed at the front end part opening of the second dripping part  12 B without using the first dripping part  11 B, as shown in of  FIG. 19 ( 1 ), by using a mold for injection molding corresponding to the outer diameter of the chamfered concave part, the second dripping part  12 B having a tapered concave part at the front end part of the opening can be formed (see  FIG. 19 ( 2 )). 
     Thereafter, as shown in  FIGS. 19 ( 3 ) and ( 4 ), a concavities and convexities-forming treatment and a surface roughening treatment by using a stamper, etc. and a fluorinating and surface roughing treatment by using fluorine plasma etching are conducted, whereby the nozzle  10 B is completed. 
     In the roughening/fluorinating treatment, the tapered chamfered concave molded part is masked so as not to be roughened and fluorinated. After roughening and fluorinating the front end part of the nozzle  10 B to form the second surface  12 Ba, the inner surface of the opening of the second surface  12 Ba is chamfered, whereby the tapered first surface  11 Ba can also be formed. In this case, the above-mentioned masking treatment becomes unnecessary. 
     [Bulwark] 
     Subsequently, an explanation will be made on a case where a bulwark  14  is provided at the front end part of the nozzle  10 A according to one or more embodiments of the present invention. 
     In the nozzle  10 A according to the first embodiment, on the front end surface of which the liquid repellency is improved by subjecting the front end part  11  to a fluorine plasma treatment or a surface roughing treatment as mentioned above, the bulwark  14  can be further provided. 
       FIG. 20  is a plan view and a cross-sectional view taken along the line A-A thereof of the front end part when a bulwark  14  is provided on the periphery of the opening of the nozzle  10 A, in which (a) shows a case where a bulwark  14  is provided on the periphery of the opening, and (b) shows a case where a bulwark  14  is not provided. 
     As mentioned above, in the fluorinated and surface-roughened front end part  11  of the nozzle  10 A according to the first embodiment, since high liquid repellency is imparted, liquid droplets poured from the container main body  2  can easily fall and drip from the opening  11 Aa of the front end part of the nozzle  10 A. Further, by surface-roughening of the front end part  11 A of the nozzle  10 A, the concavo-convex structure obtained by surface roughening and the opening  11 Aa of the nozzle  10 A may be spatially continued and intercommunicated as shown in  FIG. 20( b ) . 
     In such a case, part of the liquid droplets poured from the container main body  2  may enter and soak into the concavo-convex structure that is spatially intercommunicated with the opening  11   a.    
     If the content liquid enters and soaks into the concavo-convex structure in this way, there is a possibility that the liquid-repellent performance by the concavo-convex structure is lowered or the liquid remains at the front end part  11 A (top surface) of the nozzle  10 A, and as a result, the small quantity dripping performance and liquid dripping prevention performance of the nozzle  10 A may be deteriorated. 
     As shown in  FIG. 20( a ) , at the front end part  11 A of the nozzle  10 A, the bulwark  14  is vertically provided such that it surrounds the periphery of the opening  11 Aa. 
     By the provision of the bulwark  14 , intercommunication of the concavo-convex structure of the roughened front end part  11 A and the opening  11 Aa is shielded and stopped, as a result, liquid droplets poured from the opening  11 Aa are prevented from entering and soaking into the concavo-convex structure can be prevented. As a result, lowering in liquid-repellent performance of the roughened front end part  11 A and presence of residual liquid on the front end part  11 A can be prevented, whereby the small-quantity dripping performance and liquid dripping prevention performance of the nozzle  10 A can be maintained for a long period of time. 
     As shown in  FIG. 20( a ) , such bulwark  14  can be formed of a hierarchical concavo-convex structure (see  FIGS. 7 to 10 ) formed on the periphery of the opening  11 Aa of the front end part  11 A, and can be formed of a circumferential protruded part (see  FIG. 4( d ) ) that is formed in a protruded manner in the opening  11 Aa. 
     [Thick Wall Part] 
     When the liquid is dropped in a state where the container is inclined, the liquid droplets poured from the opening is discharged outside the nozzle after flowing along the nozzle front parts  11 A and  12 Ba (pouring mode). 
     At that time, liquid dripping phenomenon that liquid droplets move to the nozzle side surfaces  12 A and  12 B and contaminate the nozzle and the container body occurs. 
     For the nozzle  10  ( 10 A,  10 B) for which the front end part is subjected to a liquid-repellent treatment mentioned above, by providing a thick wall part  15 , liquid dripping phenomenon at the time of pouring can be prevented. 
       FIGS. 21 and 22  are each a partial cross-sectional view of the nozzle in which a thick wall part  15  is provided on the outer periphery of the front end part of the nozzle  10  according to the first embodiment, and  FIG. 21  shows a case of the nozzle  10 A according to the first embodiment and  FIG. 22  shows a case of the nozzle  10 B according to the second embodiment. 
     In these  FIGS. 21 and 22 , (a) shows a case where the thick wall part  15  is overhung relative to the top surface of the nozzle front end part, (b) shows a case where the thick wall part  15  is slanted relative to the top surface of the nozzle front end part, and (c) shows a case where no thick wall part  15  is provided in the nozzle. 
     As shown in (a) and (b) of  FIGS. 21 and 22 , the thick wall part  15  is a part that protrudes from the outer peripheral edge of the front end part of the nozzle  10  to the outside. Due to the provision of the thick wall part  15 , drainability of a liquid that moves to the outer peripheral edge of the front end part, i.e. separability between the liquid droplets falling from the outer periphery of the nozzle  10  and the liquid remaining in the nozzle  10 , can be improved. As a result, the liquid is prevented from dripping to the side surface side continuing the front end part of the nozzle  10 , and in cooperation with the high liquid repellency of the front end part, occurrence of dripping of liquid droplets poured from the opening of the nozzle  10  can be suppressed or prevented. 
     [Mechanism of Liquid Drainability] 
     As for the mechanism of the liquid drainability of the thick wall part  15 , an explanation will be made with reference to  FIGS. 23 and 24 . 
       FIG. 23  is a cross-sectional view of an essential part for explaining the drainability when a slanted thick wall part  15  is provided on the outer periphery of the front end part of the nozzle  10 .  FIG. 24  is a cross-sectional view of an essential part of the nozzle when an overhung thick wall part  15  is provided on the outer periphery of the front end part of the nozzle  10 . 
     The thick wall part  15  shown in these figures is formed as follows: When the front end part (top surface) of the nozzle  10  is heat-pressed, for example, the resin at the surface layer of the front end part is molten and a part of the molten resin is extruded radially outward from the outer peripheral edge of the tip part and is solidified. 
     Further, as shown in  FIG. 23 , for example, the shape of the thick wall part  15  may be in a shape in which the front end thereof protrudes at an acute angle (slanted shape), or in a shape in which the front end thereof protrudes in the form of droplets as shown in  FIG. 24  (overhang shape). 
     Due to the provision of such thick wall part  15 , liquid drainability at the outer peripheral edge of the nozzle  10  of content liquid poured out from the opening can be improved, whereby dripping of the content liquid from the outer periphery of the nozzle  10  can be effectively suppressed. The mechanism is explained below. 
     [Slant Mode] 
     As shown in  FIG. 23 , in a case where the thick wall part  15  is protruded at an acute angle such that it is substantially flushed with the top surface (the surface of the front end part) of the nozzle  10  (slant mode), when the liquid advancing at a contact angle θ E  reaches the outer peripheral edge (edge part) of the front end part (see  FIG. 23( a ) ), when the angle formed by the travelling surface of the liquid (the top surface of the front end part) and the outer surface of the edge part is taken as α, the liquid stays in the edge part until the advancing angle θ* (the critical contact angle of the edge part) becomes θ*=θ E +(π−α) (see  FIG. 23( b ) ). 
     This is a phenomenon known as the pinning effect in respect of the relationship between the surface tension of the liquid and the contact angle. However, as shown in FIG.  23 , if the thick wall part  15  is formed such that the front end part thereof protrudes at an acute angle (α&lt;90° (slant mode), the advance angle is increased due to the pinning effect, and the content liquid tends to stay in the thick wall part  15  due to the surface tension. 
     As a result, the drainability of the liquid that moves to the outer peripheral side of the nozzle front end part, i.e. separability of liquid droplets falling from the outer edge of the nozzle  10  and the liquid remains on the top surface side of the nozzle  10  can be improved, whereby dripping of the liquid poured from the nozzle  10  to the nozzle surface side can be suppressed. 
     As shown in  FIG. 23 , the upper surface of the thick wall part  15  is flushed with the top surface (the surface of the front end part) of the nozzle  10 , but when the thick wall part  15  is formed so that the front end thereof has a shape in which the front end protrudes at an acute angle, although not particularly shown, the thick wall part  15  may be formed such that the upper surface thereof is inclined (slanted) linearly or in a curved way with respect to the top surface of the nozzle  10 . 
     [Overhang Mode] 
     Next, as shown in  FIG. 24 , in the case where the front end of the thick wall part  15  protrudes in the form of droplets so that the traveling surface of the content liquid curves downward (overhangs) in an arc shape (overhang mode), the content liquid which has flown to the root side beyond the lowest point of the thick wall part  15  remains in the thick wall part  15  at a critical contact angle θ E  due to the surface tension. 
     At this time, when the angle formed by the tangent line L with the thick wall part  15  at its end and the top surface (front end part) of the nozzle  10  is taken as α, the advancing angle θ* (the critical contact angle of the edge part) becomes θ*=θ E +(2π−α), and the content liquid does not fall off since it is supported by a large apparent surface tension at the edge part. 
     When the content liquid drips, large droplets that cannot be supported by surface tension any longer are separated and fall, and the liquid is separated from the outer edge of the nozzle  10  and drops without dripping to the side surface side of the nozzle  10 . 
     Therefore, in this overhung mode, the drainability of the liquid that moves to the outer edge side of the front end part, i.e. separability of the liquid droplets falling from the outer peripheral edge of the nozzle  10  and the liquid remaining on the top surface of the nozzle  10  can be improved, whereby the liquid poured from the nozzle  10  is suppressed from dripping to the nozzle surface side. 
     As described above, in the present embodiment, it is possible to form, by heat pressing or the like, the thick wall part  15  on the nozzle  10  that is molded into a predetermined shape by injection molding or the like, and by apparently increasing the surface tension of the liquid described by the pinning effect, it becomes possible to allow a residual liquid of the content liquid poured out of the container to be accumulated in the thick wall part  15  easily, thereby improving the liquid drainability. 
     As a result, it is possible to improve the drainability of the liquid that moves to the outer peripheral edge side of the front end part of the nozzle  10 , and, in combination with high liquid-repellent performance (liquid droplet falling property) of the fluorinated and surface-roughened front end part, it is possible to prevent effectively the liquid poured from the nozzle  10  from dripping to the nozzle side surface side. 
     [Method for Producing Thick Wall Part] 
     Subsequently, a method for producing the thick wall part  15  provided at the front end part of the nozzle  10  ( 10 A,  10 B) will be explained with reference to  FIG. 25 . 
       FIG. 25  is an explanatory view schematically showing the method for producing the thick wall part  15  by heat pressing in the nozzle  10  ( 10 A,  10 B) according to one or more embodiments of the present invention, in which (a) shows a state prior to heat pressing in which the opening (discharge port) of the nozzle is made large in advance such that it is not blocked by heat pressing; (b) shows a state after heat pressing; and (c) shows a state in which the opening of the nozzle is blocked by heat pressing. 
     As shown in  FIG. 25( a ) , the thick wall part  15  provided at the nozzle  10  can be formed by pressing a hot plate P for conducting heat pressing against the surface of the front end part, followed by heating and pressurizing, whereby the thick wall part  15  protruding from the outer peripheral edge of the nozzle  10  to the outside of the radial direction can be formed. 
     The shape, size, etc. of the thick wall part  15  formed by heat pressing can be determined by appropriately adjusting the temperature of a hot plate P when pressing the hot plate P when heat pressing the front end part of the nozzle  10 , the pressing force of pressing the hot plate P, the time for which the hot plate P, etc., whereby the desired thick wall part  15  can be formed. 
     The heat pressing for forming the thick wall part  15  can be conducted simultaneously with a step of forming prescribed concavities and convexities by a stamper on the surface of the front end part of the nozzle  10  shown in  FIG. 16  and  FIG. 18( a ) ( 2 ). 
     Specifically, the stamper for forming concavities and convexities on the front end part of the nozzle  10  (see  FIG. 16  and  FIG. 18( a ) ( 2 )) is formed of the hot plate P shown in  FIG. 25( a ) , and concavities and convexities are formed on the top surface of the front end part and, simultaneously, the thick wall part  15  can be formed at the outer peripheral edge of the front end part. 
     Further, when the thick wall part  15  is formed by heat pressing, the size and shape of the resin after the resin is molten and swollen may be predicted and assumed and that the nozzle length and the nozzle opening be designed larger for the nozzle  10  prior to being subjected to heat pressing. 
     In the case of the nozzle  10  for small-quantity dripping of a container for instillation of eye drops, the opening for pouring liquid droplets is small, and the opening (discharge port) may become narrow or blocked by heat pressing (see  FIG. 25( c ) ). 
     As shown in  FIG. 25( a ) , by forming the opening of the nozzle  10  larger in advance in order that the opening (discharge port) is not blocked by heat pressing, the opening can have a prescribed size and length even if the thick wall part  15  is formed by heat pressing (see FIG.  25 ( b )). 
     In addition, since the thick wall part  15  can be formed by heat pressing, when producing the nozzle  10 , it is not required to modify the existent mold and also it is not required to taken into consideration disadvantages such as deformation when taking out from the mold. As a result, the cost incurred for molds can be suppressed to low. 
     As mentioned above, by the nozzle  10  according to one or more embodiments of the present invention, the liquid repellency at the front end of the nozzle  10  can be improved and maintained by subjecting the front end part  10  to a fluorine plasma treatment or a surface roughening treatment. 
     In the nozzle  10 A according to one or more embodiments of the present invention, the plastic molded body constituting the nozzle main body is formed of a non-fluorine-based resin such as polyolefin or polyester, but on the surface of the front end part  11 A, fluorine atoms are incorporated into a molecular chain of the resin 
     On the surface of the fluorinated front end part  11 A, a roughened surface composed of fine concavities and convexities is formed, according to need. 
     When the liquid is poured from the inside of the container, the front end part  11 A of the fluorinated and roughened nozzle  10 A has further high liquid repellency due to improvement in liquid repellency by fluorine atoms and existence of an air pocket because of a roughened surface composed of concavities and convexities (gas-liquid contact). 
     In the nozzle  10 A to which liquid repellency is imparted as mentioned above, falling property of liquid droplets is improved by liquid repellency of the top surface of the front end part  11 A, and presence of residual liquid on the top surface of the nozzle can be suppressed or prevented. 
     Further, by forming the bulwark  14  on the front end part  11 A, it is possible to prevent soaking of liquid droplets to the top surface of the front end part  11 A, whereby deterioration of liquid repellency can be improved, and the small-quantity dripping performance and liquid dripping prevention performance of the nozzle  10 A can be maintained for a long period of time. 
     Furthermore, by forming the thick wall part  15  on the outer peripheral edge of the front end part  11  of the nozzle  10 , it is possible to improve the drainability of poured liquid droplets, and in combination with high liquid repellency (falling property of liquid droplets) by fluorinating and surface roughing, occurrence of liquid dripping can be suppressed or prevented. 
     In the nozzle  10 B according to one or more embodiments of the present invention, the front end surface of the nozzle  10 B is constituted by a plurality of surfaces having different surface free energies, i.e. a first surface  11 Ba and a second surface  12 Ba, and by allowing the first surface  11 Ba positioned at the center of the nozzle to be a high-energy surface with low liquid repellency and the second surface  12 Ba positioned therearound to be a low-energy surface with high liquid repellency, reduction in amount of dropped liquid droplets is realized while inducing liquid droplets such that they are formed at the center of the opening of the nozzle  10 B. 
     As a result, stable small-quantity dripping can be reliably conducted without causing deterioration, etc. in dripping performance or causing variations in dripping quantity even if repeatedly used, whereby a nozzle for use in a container for instillation of eye drops can be realized. 
     Further, in the nozzle  10 B to which liquid repellency is imparted, liquid falling property is improved by liquid repellency at the top surface of the front end part, and presence of residual liquid on the top surface of the nozzle can be suppressed or prevented. 
     Further, by forming the thick wall part  15  on the outer peripheral edge of the front end part of the nozzle  10 B, the drainability of the liquid droplets poured can be improved, and in combination with high liquid-repellent performance (falling property of liquid droplets) by fluorinating and surface roughing, occurrence of liquid dripping can be suppressed or prevented. 
     As mentioned above, in the nozzle  10 B according to the second embodiment, by imparting a prescribed liquid-repellent treatment and a liquid-repellent structure to the front end part of the nozzle from which the liquid is poured, the surface of the front end part of the nozzle  10 B, i.e. the second surface  12 Ba serving as a low-energy surface is provided. 
     In addition, from the viewpoint of eliminating variations in droplet quantity due to biased liquid repellency of the nozzle surface or entrainment of air, by positively creating a biased liquid repellency to induce the liquid droplets are always formed at the center of the nozzle  10 B, a surface having a lower liquid repellency than that of the second surface  12 Ba that is subjected to a liquid-repellent treatment, i.e. a first surface  11 Ba serving as a high energy surface, is provided at the nozzle center. 
     As a result, the first surface  11 Ba serving as a high-energy surface is present on the outer periphery of the opening of the nozzle  10 B, and around it, there is formed the second surface  12 Ba that serves as a low energy surface having higher water repellency than the first surface  11 Ba continues, the liquid droplet poured from the nozzle  10 B is positively repelled from the second surface  12 Ba and positively adsorbed to the first surface  11 Ba, and the liquid droplets are formed and induced at the nozzle center in a state of being adsorbed and contacted only with the first surface  11 Ba. 
     Therefore, even if the second surface  12 Ba has variations in liquid repellency, or even if air entrapping is present in liquid droplets to be poured, the droplets are always guided so as to be formed at the center of the opening of the nozzle  10 B without being biased to the second surface side  12 Ba or dispersed. 
     Accordingly, in the nozzle  10 B according to the second embodiment, reliable and stable pouring and dripping can be conducted without causing biasing or variations of liquid droplets. 
     In addition, by applying a fluorine plasma treatment or a surface roughening treatment to the second surface  12 Ba which serves as a low energy surface having high liquid repellency, it is possible to improve and maintain the liquid repellency of the nozzle front end surface. That is, the plastic molded body constituting the second surface  12 Ba of the nozzle  10 B is formed of a non-fluorine-based resin such as polyolefin or polyester, but in the part constituting the second surface  12 Ba, fluorine atoms are incorporated into a molecular chain of a non-fluorine-based resin. Further, in the fluorinated second surface  12 Ba that is fluorinated, a roughened surface composed of fine concavities and convexities is formed according to need. 
     In the second surface  12 Ba of the fluorinated and surface-roughened nozzle  10 B, when a liquid is poured from the inside of the container, due to improved liquid repellency and presence of an air pocket due to the presence of a roughened surface formed of fine concavities and convexities (gas-liquid contact), further high liquid repellency is ensured. As a result, the poured liquid droplets are induced such that they are formed on the first surface  11 Ba at the center of the nozzle without adhering to the second surface  12 Ba. 
     With respect to the fluorination of the front end part of the nozzle  10  according to one or more embodiments of the present invention, fluorine atoms are incorporated into a molecular chain of the non-fluorine-based resin constituting the surface of the front end part of the nozzle, and hence, fluorine atoms are stably present on the surface of the nozzle front end part without falling off. Therefore, even when the liquid is repeatedly poured, the liquid repellency is not impaired. 
     That is, the nozzle  10  of which the front end part is fluorinated and roughened, excellent liquid repellency can be maintained for a long period of time, and if the liquid repeatedly contacts, the liquid repellency as high as that of the initial stage is maintained, and as a result, small-quantity dripping becomes possible. 
     Accordingly, by setting the inner diameter of the nozzle  10  and the surface area or shape of the first surface  11 Ba to be a prescribed value, the dripping quantity of the liquid (eye drop) poured from the nozzle  10  can be an arbitrary value, e.g. 10 μl or less. As a result, the dripping quantity can be small and optimized, whereby the eye drop quantity and the dripping quantity that are optimum to the eyes of a human being can be realized. 
     The front end part of the fluorinated and roughened nozzle  10  is protected by the cap  20 . In this case, the inner surface of the cap  20  does not abut and contact the fluorinated and roughened surface of the nozzle  10 , and the inside of the container is protected in a sealed state with the nozzle  10  being covered by the cap  20  in a state that the cap  20  does not contact the nozzle surface. 
     Therefore, even if the cap  20  is repeatedly attached and detached, the fluorinating/roughening performance of the front end part of the nozzle  10  is not impaired, and until the liquid (eye drop) in the container is lost, the small amount dripping performance of the nozzle  10  can be exhibited. 
     As mentioned above, by the nozzle  10  according to this embodiment, not only reduction in dripping quantity in the eye drop container  1  can be realized, but also liquid dripping or presence of residual liquid on the top surface of the nozzle can be prevented. 
     Further, by reliably protecting the front end part of the nozzle  10  with the cap  20  while taking care not to deteriorate the functions thereof, it is possible to stably maintain the performance of the nozzle according to one or more embodiments of the present invention, and instillation operation can be conducted until eye drops in the instillation container for eye drops  1  are run out. 
     EXAMPLES 
     Examples of the nozzle according to one or more embodiments of the present invention will be explained below. 
     Here, embodiments of the present invention will be explained more detail with reference to the examples below, however it should be understood that embodiments of the present invention shall not be limited at all by the examples below. 
     First Embodiment 
     First, examples of a nozzle  10 A according to one or more embodiments of the present invention will be explained. 
     Examples 1 to 3 according to one or more embodiments of the present invention and Comparative Examples 1 to 3 are shown in the following Table 1. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 1 
               
             
            
               
                   
                   
               
               
                   
                 Molding conditions 
                 Results of evaluation 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 Dia- 
                   
                   
                   
                   
                 Small- 
                 Dripping 
                   
                   
               
               
                   
                 meter 
                 Ni stamper 
                   
                 Shape of    
                   
                 quantity 
                 quantity 
                 Dripping 
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                   
                 of 
                 Second- 
                 Hierar- 
                 Plasma 
                 Primary 
                 Secondary 
                 Tertiary 
                 Fluorine 
                 dripping 
                 control 
                 durability 
                   
               
               
                   
                 opening 
                 ary 
                 chical 
                 treat- 
                 
                   
                 
                 
                   
                 
                 
                   
                 
                 content 
                 performance 
                 performance 
                 performance 
                 Overall 
               
               
                   
                 Mm 
                 
                   
                 
                 
                   
                 
                 ment 
                 φs 
                 Ra/RSm 
                 Ra/RSm 
                 F/C 
                 μL 
                 r 2   
                 μL 
                 evaluation 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
               
               
               
            
               
                 Example 1 
                 φ0.1 
                 X 
                 X 
                 ◯ 
                 — 
                 — 
                 7.5 × 10 −3   
                 74% 
                 ◯(1) 
                 ◯(0.92) 
                 ◯(1) 
                 ◯ 
               
               
                   
                 φ0.2 
                   
                   
                   
                   
                   
                   
                   
                 ◯(2) 
                   
                 ◯(2) 
               
               
                   
                 φ0.3 
                   
                   
                   
                   
                   
                   
                   
                 ◯(4) 
                   
                 ◯(4) 
               
               
                   
                 φ0.4 
                   
                   
                   
                   
                   
                   
                   
                 ◯(8) 
                   
                 ◯(8) 
               
               
                 Example 2 
                 φ0.1 
                 X 
                 ◯ 
                 ◯ 
                 0.1 
                 264 × 10 −3   
                 7.5 × 10 −3   
                 74% 
                 ◯(1) 
                 ◯(0.83) 
                 ◯(1) 
                 ◯ 
               
               
                   
                 φ0.2 
                   
                   
                   
                   
                   
                   
                   
                 ◯(1) 
                   
                 ◯(2) 
               
               
                   
                 φ0.3 
                   
                   
                   
                   
                   
                   
                   
                 ◯(3) 
                   
                 ◯(4) 
               
               
                   
                 φ0.4 
                   
                   
                   
                   
                   
                   
                   
                 ◯(7) 
                   
                 ◯(8) 
               
               
                 Example 3 
                 φ0.1 
                 ◯ 
                 X 
                 ◯ 
                 — 
                 264 × 10 −3   
                 7.5 × 10 −3   
                 74% 
                 ◯(1) 
                 ◯(0.83) 
                 ◯(1) 
                 ◯ 
               
               
                   
                 φ0.2 
                   
                   
                   
                   
                   
                   
                   
                 ◯(3) 
                   
                 ◯(2) 
               
               
                   
                 φ0.3 
                   
                   
                   
                   
                   
                   
                   
                 ◯(4) 
                   
                 ◯(4) 
               
               
                   
                 φ0.4 
                   
                   
                   
                   
                   
                   
                   
                 ◯(4) 
                   
                 ◯(8) 
               
               
                 Comp. 
                 φ0.1 
                 X 
                 X 
                 X 
                 — 
                 — 
                 — 
                 0% 
                 X(29) 
                 ◯(0.87) 
                 X(29) 
                 X 
               
               
                 Ex. 1 
                 φ0.2 
                   
                   
                   
                   
                   
                   
                   
                 X(44) 
                   
                 X(44) 
               
               
                   
                 φ0.3 
                   
                   
                   
                   
                   
                   
                   
                 X(56) 
                   
                 X(56) 
               
               
                   
                 φ0.4 
                   
                   
                   
                   
                   
                   
                   
                 X(56) 
                   
                 X(56) 
               
               
                 Comp. 
                 φ0.1 
                 X 
                 ◯ 
                 X 
                 0.1 
                 264 × 10 −3   
                 — 
                 0% 
                 ◯(1) 
                 ◯(0.60) 
                 X(30) 
                 X 
               
               
                 Ex. 2 
                 φ0.2 
                   
                   
                   
                   
                   
                   
                   
                 ◯(1) 
                   
                 X(45) 
               
               
                   
                 φ0.3 
                   
                   
                   
                   
                   
                   
                   
                 ◯(1) 
                   
                 X(56) 
               
               
                   
                 φ0.4 
                   
                   
                   
                   
                   
                   
                   
                 ◯(4) 
                   
                 X(57) 
               
               
                 Comp. 
                 φ0.1 
                 ◯ 
                 X 
                 X 
                 — 
                 264 × 10 −3   
                 — 
                 0% 
                 ◯(1) 
                 ◯(0.90) 
                 X(29) 
                 X 
               
               
                 Ex. 3 
                 φ0.2 
                   
                   
                   
                   
                   
                   
                   
                 ◯(1) 
                   
                 X(42) 
               
               
                   
                 φ0.3 
                   
                   
                   
                   
                   
                   
                   
                 ◯(3) 
                   
                 X(55) 
               
               
                   
                 φ0.4 
                   
                   
                   
                   
                   
                   
                   
                 ◯(4) 
                   
                 X(57) 
               
               
                   
               
            
           
         
       
     
     Examples 1 to 3 and Comparative Examples 1 to 3 shown in Table 1 were tested under the following condition: 
     (1) Test sample
 
§Nozzle main body
         Material
           Low density polyethylene
               Grade: LJ8041   
               
           Size: 10 mm in diameter×10 mm in length   Opening size: 0.1, 0.2, 0.3, and 0.4 mm   Method of production of nozzle main body
           A nozzle with the above-mentioned opening was obtained by an injection molding process.   
               

     §Stamper 
     
         
         
           
             Method of production of hierarchical and convexo-concave-patterned stamper (stamper on which primary convexo-concave pattern and secondary convexo-concave pattern be formed)
           A master stamper was produced by a photolithographic technique, and a Cu master stamper with the primary convexo-concave pattern being impressed was produced by a Cu-electroforming process.   Wet etching was conducted for the surface of the Cu master stamper to form a roughened surface, and then, a stamper with a secondary convexo-concave pattern being impressed by a Ni-electroforming process.
               Primary convexo-concave pattern
                   φs=0.1 (s=20 μm, d=30 μm, and pitch=200 μm)   
                   Secondary convexo-concave pattern
                   Ra/RSm=264×10 −3  (Ra=933 μm, and RSm=3.5 μm)   
                   
               
         
             Method of production of secondary convexo-concave patterned stamper
           Wet etching was conducted for a flat surface of a Cu master stamper to form a roughened surface, and then, a stamper with a secondary convexo-concave pattern being impressed by a Ni-electroforming process.
               Ra/RSm=264×10 −3  (Ra=933 μm, and RSm=3.5 μm)
 
§Transfer molding
   
               
         
             The stamper was heated to a temperature of 230° C. by infra-red radiation heating with a halogen lamp, impressed to the front edge of the nozzle for one second, followed by cooling to obtain a front edge of the nozzle to which the convexo-concave pattern formed on the surface of the stamper was transfer-molded.
 
§Carbon fluoride plasma treatment
 
             After the transfer molding, carbon fluoride plasma treatment was carried out under the following condition:
           Apparatus
               Discharge type: Low atmospheric pressure surface wave plasma   Electric power source: 1500 W@2.45 GHz   
               Condition
               Degree of vacuum: 4 Pa   Material gas: CF 4  100 sccm   Duration of plasma treatment: 20 seconds
 
(2) Performance evaluation
 
§Evaluation on convexo-concave shape
   
               
         
             Method of measurement 
             As to the edge of the nozzle to which the convexo-concave pattern was transferred, measurement for the primary convexo-concave pattern and the secondary convexo-concave pattern were conducted by using a white-light interferometer, and measurement for the tertiary convexo-concave pattern was conducted by using an atomic force microscope (AFM). The area ratio φs, arithmetic average roughness Ra, and average length RSm were calculated. 
             Measurement condition of white-light interferometer 
             Measurement device: New View 7300 manufactured by ZYGO Corporation 
             Object lens magnification: 50-fold 
             Ocular lens magnification: 2.0-fold 
             Cutoff value of long wavelength side λc=13.846155 μm 
             Cutoff value of short wavelength side λs=346.155 nm 
             Measurement condition of AFM 
             Measurement device: Nano Scope III manufactured by Veeco Instruments, Inc. 
             Cutoff value of long wavelength side λc=0.0824 μm
 
§Determination of fluorine atom content
 
             Method of measurement 
             Wide-band spectral analysis was conducted for the surface of the substrate by using an X-ray photoelectron spectrometer (XPS) to measure the amount of elements that exist on the surface, and the atomic ratio of fluorine atoms to carbon atoms (F/C) was calculated. 
             Measurement device: K-Alpha manufactured by Thermo Fisher Scientific K.K.
 
§Evaluations on small-quantity dripping quality and control performance of dripping quantity
 
             Testing method
           The eye drop container main body was filled with real liquid, subjected to carbon fluoride plasma treatment, and capped with the nozzle formed by transfer molding.   Ten or more drops of the real liquid were dripped on a paper dish set on an electronic balance, and measured the total weight of the drops.   The weight of one drop was calculated by dividing the total amount of the drops by the number of the drops.   
         
             Real liquid
           C CUBE manufactured by RHOTO Pharmaceutical Co., Ltd.   
         
             Measurement device: Even balance ML802 manufactured by Mettler-Toledo International Inc. 
             Evaluation criterion
           The case where the diameter of the opening and the dripping quantity are related with a positive correlation and the correlation coefficient r2≧0.7, was judged as the nozzle have control performance of dripping quantity.   The case where the dripping quantity≦10 μL was judged as the nozzle have small-quantity dripping performance.
 
§Evaluation on durability to repeated dripping
   
         
             Testing method
           One hundred drippings were conducted to contaminate the surface.   The dripping quantity of the contaminated nozzle was measured.   
         
             Real liquid
           C CUBE manufactured by RHOTO Pharmaceutical Co., Ltd.   
         
             Evaluation criterion
           The case where the dripping quantity≦10 μL was judged as the nozzle have durability to repeated drippings.   
         
           
         
       
    
     Second Embodiment 
     Next, examples of the nozzle according to one or more embodiments of the present invention will be explained with reference to Table 2. 
     
       
         
           
               
               
               
             
               
                   
                 TABLE 2 
               
             
            
               
                   
                   
               
               
                   
                 Examples 
                 Com. Examples 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                   
                 (1) 
                 (2) 
                 (3) 
                 (4) 
                 (5) 
                 (6) 
                 (1) 
                 (2) 
               
               
                   
                   
               
            
           
           
               
               
               
               
               
               
               
               
               
               
            
               
                 Molding 
                 Drawings to be 
                 FIG. 5-a 
                 FIG. 5-b 
                 FIG. 5-d 
                 FIG. 5-e 
                 FIG. 5-f 
                 FIG. 5-g 
                 FIG. 3-a 
                 FIG. 3-b 
               
               
                 method 
                 referred 
               
               
                   
                 Nozzle base 
                 1 
                 2 
                 2 
                 1 
                 1 
                 3 
                 3 
                 3 
               
               
                   
                 First dripping part 
                 a 
                 b 
                 b 
                 c 
                 d 
                 — 
                 — 
                 — 
               
               
                   
                 Protruding part 
                 ∘ 
                 ∘ 
                 x 
                 ∘ 
                 ∘ 
                 — 
                 — 
                 — 
               
               
                   
                 fabricating step 
               
               
                   
                 Roughening step 
                 ∘ 
                 ∘ 
                 ∘ 
                 ∘ 
                 ∘ 
                 ∘ 
                 x 
                 ∘ 
               
               
                   
                 Fluorinating 
                 ∘ 
                 ∘ 
                 ∘ 
                 ∘ 
                 ∘ 
                 ∘ 
                 x 
                 ∘ 
               
               
                   
                 plasma treatment 
               
               
                   
                 step 
               
               
                   
                 Burrs-forming 
                 x 
                 x 
                 x 
                 x 
                 x 
                 ∘ 
                 x 
                 x 
               
               
                   
                 step 
               
               
                 Evaluation of 
                 Small-quantity 
                 ∘ 
                 ∘ 
                 ∘ 
                 ∘ 
                 ∘ 
                 ∘ 
                 x 
                 ∘ 
               
               
                 performance 
                 dripping 
                 (5.0 μL) 
                 (7.0 μL) 
                 (4.0 μL) 
                 (4.4 μL) 
                 (9.2 μL) 
                 (4.9 μL) 
                 (40 μL) 
                 (3.7 μL) 
               
               
                   
                 performance 
               
               
                   
                 Reproducibility of 
                 ∘ 
                 ∘ 
                 Δ 
                 ∘ 
                 ∘ 
                 ∘ 
                 x 
                 x 
               
               
                   
                 dripping quantity 
                 (3.0%) 
                 (3.1%) 
                 (4.2%) 
                 (3.0%) 
                 (3.1%) 
                 (3.2%) 
                 (18%) 
                 (6.2%) 
               
            
           
           
               
               
               
               
               
               
               
               
               
            
               
                 Overall evaluation 
                 ∘ 
                 ∘ 
                 Δ 
                 ∘ 
                 ∘ 
                 ∘ 
                 x 
                 x 
               
               
                   
               
               
                 (Nozzle base 1) Resin: Polyethylene (LJ8041 manufactured by JAPAN POLYETHYLENE CORPORATION) Molding method: injection molding method Outer shape: 6 mm in diameter × 5 mm in length Diameter of opening: 0.8 mm 
               
               
                 (Nozzle base 2) Resin: Polyethylene (LJ8041 manufactured by JAPAN POLYETHYLENE CORPORATION) Molding method: injection molding method Outer shape: 6 mm in diameter × 5 mm in length Diameter of opening: 1.2 mm 
               
               
                 (Nozzle base 3) Resin: Polyethylene (LJ8041 manufactured by JAPAN POLYETHYLENE CORPORATION) Molding method: injection molding method Outer shape: 6 mm in diameter × 5 mm in length Diameter of opening: 0.4 mm 
               
               
                 (First dripping part a) Resin: Polyethylene (LJ8041 manufactured by JAPAN POLYETHYLENE CORPORATION) Molding method: injection molding method Outer shape: 0.8 mm in diameter × 0.4 mm in inner diameter × 1 mm in length Shape of first surface: rectangle 
               
               
                 (First dripping part b) Resin: Polyethylene (LJ8041 manufactured by JAPAN POLYETHYLENE CORPORATION) Molding method: injection molding method Outer shape: 1.2 mm in diameter × 0.4 mm in inner diameter × 1 mm in length Shape of first surface: rectangle 
               
               
                 (First dripping part c) Resin: Polyethylene (LJ8041 manufactured by JAPAN POLYETHYLENE CORPORATION) Molding method: injection molding method Outer shape: 0.8 mm in diameter × 0.4 mm in inner diameter × 1 mm in length Shape of first surface: reducing taper (tip angle: 30°) 
               
               
                 (First dripping part d) Resin: Polyethylene (LJ8041 manufactured by JAPAN POLYETHYLENE CORPORATION) Molding method: injection molding method Outer shape: 0.8 mm in diameter × 0.4 mm in inner diameter × 1 mm in length Shape of first surface: increasing taper (tip angle: 45°) 
               
               
                 (Surface-roughening step) A stamper made of Ni, on which a hierarchized convexo-concave structure was formed, was heated to a temperature of 230° C. and hot-pressed to the nozzle base to form a roughened surface. Primary convexo-concave structure Line &amp; space pattern Area ratio = 0.2 Secondary convexo-concave structure Ra/Rsm = 250 × 10 −3   
               
               
                 (Fluorine plasma treatment step) Surface wave plasma device Power outlet: 1.5 kW@2.45 GHz Material gas: CF 4  200 sccm Degree of vacuum: 4 Pa Duration of treatment: 20 seconds 
               
               
                 (Burrs-forming step) The opening of the nozzle base was knocked a hole by a drill having a diameter of 0.4 mm to form burrs. 
               
               
                 (Protruding part fabrication step) The first dripping part was inserted into the opening of the nozzle base. In the fabrication, the dripping part was protruded from the surface of the nozzle base by 0.3 mm. 
               
               
                 (Dripping test) The nozzle was inserted to a main body of an container for instillation of eye drops filled with ROHTO C CUBE. The container main body was pushed to drip 20 drops of the filling fluid, and the total amount of the 20 drops was measured. 
               
               
                 (Evaluations on small-quantity dripping performance) An average amount value of the drops was calculated and the small quantity-dripping performance was evaluated. ∘: Average amount value ≦10 μL x: Average amount value &gt;10 μL 
               
               
                 (Evaluation on reproducibility of dripping quantity) An average amount of drops and the standard deviation were calculated, and CV was calculated by means of the following expression to conduct the evaluation: CV (%) = (Standard deviation)/(Average value) × 100 ∘: CV ≦3.3% Δ: 3.3 &lt; CV ≦ 5.0% x: CV &gt;5.0% 
               
            
           
         
       
     
     As above, the nozzle of one or more embodiments of the present invention is explained with reference to embodiments. However, the present invention is not restricted to the above-mentioned embodiments, and it is needless to say that various kinds of modifications within the scope of the present invention are applicable. 
     For instance, in the above-mentioned embodiments, a container for instillation of eye drops is described as an application object of the nozzle of one or more embodiments of the present invention. However, the application object is not limited to the container for instillation of eye drops. Namely, the nozzle of one or more embodiments of the present invention can also be used for a nozzle or inlet, other than the container for instillation of eye drops, that is desired to drip a fluid in a predetermined quantity per drop. For example, the nozzle of one or more embodiments of the present invention can be used for a container for a medicine other than eye drops, a container for seasoning such as soy source or source, a container for chemical product such as detergent or cosmetics, and the like; a nozzle for various kinds of containers, a nozzle for medical apparatus or laboratory instrument, and a nozzle of a device for dripping a liquid. 
     The nozzle of one or more embodiments of the present invention can be suitably used as a nozzle for dripping fluid in a small amount, for example, for a container for instillation of eye drops or the like. 
     Although the disclosure has been described with respect to only a limited number of embodiments, those skilled in the art, having benefit of this disclosure, will appreciate that various other embodiments may be devised without departing from the scope of the present invention. Accordingly, the scope of the invention should be limited only by the attached claims. 
     DESCRIPTION OF REFERENTIAL NUMERALS 
     
         
           1  Container for instillation of eye drops 
           2  Container main body 
           10 ,  10 A,  10 B Nozzle 
           11 A Front edge part 
           11 Aa Opening 
           11 B First dripping part 
           11 Ba First surface 
           12 A Side surface part 
           12 B Second dripping part 
           12 Ba Second surface 
           14  Bulwark 
           15  Thick wall part 
           20  Cap 
           21  Nozzle-abutting part 
           100  Roughened surface 
           160  Primary convexo-concave surface 
           160   a  Concave part 
           160   b  Convex part 
           165  Secondary convexo-concave surface 
           170  Liquid droplet