Abstract:
A syringe kit for mixing two medicinal fluids includes first and second barrels adapted to contain medicinal fluids therein. The first barrel includes a connecting tube portion at a tip portion thereof having a male screw on an outer periphery, and an inner tapered surface on an inner periphery. The second barrel includes a nozzle portion at a tip portion thereof having a screw tube portion with a female screw on an inner periphery thereof freely engageable with the male screw, and an outer tapered surface fitting to the inner tapered surface on the inner periphery. At least a surface of the male screw and the outer periphery of the connecting tube portion of the first barrel, or a surface of the female screw and the inner periphery of the screw tube portion of the second barrel are roughened to a surface roughness in a range between Ra1.0 and Ra2.0.

Description:
TECHNICAL FIELD 
       [0001]    The present invention relates to a syringe kit for mixing two medicinal fluids or chemicals which is used for mixing a medicinal fluid in one barrel with a medicinal fluid in the other barrel. 
       BACKGROUND ART 
       [0002]    It is generally known to use a so-called syringe kit for mixing two medicinal chemicals wherein a medicinal chemical contained in one barrel is mixed with a medicinal chemical contained in the other barrel by screwing together the tip portion of one barrel having a plunger and the tip portion of the other barrel having a plunger so as to communicate with each other (see Patent Document 1, for example). 
         [0003]    Patent Document 1: Japanese Laid-open Patent Application, Tokuhyo 2003-518411 
       DISCLOSURE OF INVENTION 
     Problems to be Resolved by the Invention 
       [0004]    In this type of syringe kits including a syringe kit for mixing two medicinal chemicals shown in Patent Document 1, the aforementioned one barrel and the other barrel are usually made of an injection-molded synthetic resin and have smooth mirror surfaces. Because of this configuration, a stick and slip phenomenon (a friction vibration phenomenon where the friction surfaces stick and slip repeatedly) tends to occur on the screwed surfaces when the tip portion of one barrel and the tip portion of the other barrel are screwed together before mixing two medicinal chemicals and therefore it becomes a cause of disturbing smooth and steady operations. 
         [0005]    The present invention has been made in view of the problems in the prior art and provides a syringe kit for mixing two medicinal chemicals which can prevent stick and slip phenomena which tend to occur when the tip potion of one barrel and the tip portion of the other barrel are screwed together before mixing two medicinal chemicals. 
       Means for Solving the Problems 
       [0006]    In order to resolve the aforementioned problems, a syringe kit for mixing two medicinal chemicals according to the present invention is constituted as a syringe kit for mixing two medicinal chemicals which is used for mixing a medicinal chemical in a first barrel and a medicinal chemical in a second barrel by connecting the tip portion of the first barrel having a plunger to the tip portion of the second barrel having a plunger so as to communicate with each other, wherein a connecting tube portion is formed at the tip portion of the first barrel, the outer periphery of the connecting tube portion has a male screw, the inner periphery of the connecting tube portion has an inner tapered surface, a screw tube portion and a nozzle portion are formed at the tip portion of the second barrel, the inner periphery of the screw tube portion has a female screw which is screwed together with the male screw on the outer periphery of the connecting tube portion in a freely removable manner, the outer periphery of the nozzle portion has an outer tapered surface which fits to the inner tapered surface on the inner periphery of the connecting tube portion, either the outer periphery of the connecting tube portion of the first barrel and the surface of the male screw or the inner periphery of the screw tube portion of the second barrel and the surface of the female screw is roughened, or both of them are roughened, so as to have a surface roughness in a range between Ra1.0 and Ra2.0, and therefore it is possible to prevent stick and slip phenomena between the two members. 
         [0007]    In a syringe kit for mixing two medicinal chemicals according to the present invention, it is preferable to set the taper angle of the inner tapered surface of the connecting tube portion of the first barrel and the outer tapered surface of the nozzle portion of the second barrel to a range between 6% and 12% (a degree of taper representing the ratio of a change in diameter to a length by a percentage; it is also represented as 6-12/100), because the taper-fitted connection between the two members and the disengagement from the taper-fitted condition become smooth. Additionally, it is preferable to configure so that the tip portion of the nozzle portion is positioned in the connecting tube portion in a taper-fitted condition of the two members, because a gasket of the plunger of the first barrel can slide in the first barrel having a sufficient stroke when the medicinal chemical in the first barrel is mixed with the medicinal chemical in the second barrel. 
         [0008]    In a syringe kit for mixing two medicinal chemicals according to the present invention, it is also preferable to form the first barrel and the second barrel by cyclic polyolefin which has a high transparency, a high steam sterilization property and a good medical agent non-absorption property. 
       Effect of Invention 
       [0009]    In a syringe kit for mixing two medicinal chemicals according to the present invention, it is possible to prevent stick and slip phenomena which tend to occur when a male screw on the outer periphery of a connecting tube portion of a first barrel and a female screw on the inner periphery of a screw tube portion of a second barrel are screwed together or they are released from the screwed condition, and it is possible to ensure smooth and steady operations. 
     
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         [0010]      FIG. 1  shows an exploded perspective view showing a configuration of a syringe kit for mixing two medicinal chemicals according to one embodiment of the present invention. 
           [0011]      FIG. 2  shows an enlarged perspective view of the first plunger and the first barrel shown in  FIG. 1 . 
           [0012]      FIG. 3  shows a longitudinal cross-sectional view of the first barrel shown in  FIG. 2 . 
           [0013]      FIG. 4  shows an enlarged perspective view of the second plunger and the second barrel shown in  FIG. 1 . 
           [0014]      FIG. 5  shows a longitudinal cross-sectional view of the second barrel shown in  FIG. 4 . 
           [0015]      FIG. 6  shows a side view of the first barrel shown in  FIG. 3 . 
           [0016]      FIG. 7  shows a perspective view of a connected condition of a syringe kit for mixing two medicinal chemicals according to one embodiment. 
           [0017]      FIG. 8  shows a longitudinal cross-sectional view of the first barrel and the second barrel in a connected condition shown in  FIG. 7 . 
       
    
    
     DETAILED DESCRIPTION OF THE INVENTION 
       [0018]    One embodiment of a syringe kit for mixing two medicinal chemicals according to the present invention will be described below referring to the attached drawings. A syringe kit for mixing two medicinal chemicals according to one embodiment is used to mix a medicinal chemical A and a medicinal chemical B when necessary, for example. 
         [0019]    As shown in  FIG. 1 , a syringe kit for mixing two medicinal chemicals according to one embodiment comprises a first barrel  2  (see  FIGS. 2 and 3 ) and a second barrel  4  (see  FIGS. 4 and 5 ), wherein a first plunger  1  is inserted into the first barrel  2  in a freely slidable manner and a medicinal chemical A is contained in the inner space in advance, and a second plunger  3  is inserted into the second barrel  4  in a freely slidable manner and a medicinal chemical B is contained in the inner space in advance. 
         [0020]    The first plunger  1  has a gasket (not shown in drawings) and an end plate  1 A, wherein the gasket is attached to the tip portion which faces the inner space of the first barrel  2  and the end plate  1 A is formed at the rear end portion of the first plunger  1  which protrudes from the rear end portion of the first barrel  2 . The second plunger  3  is similarly configured and the second plunger  3  has a gasket (not shown in drawings) at the tip portion which faces the inner space of the second barrel  4 , and an end plate  3 A is formed at the rear end portion of the second plunger  3  which protrudes from the rear end portion of the second barrel  4 . 
         [0021]    Although the material constituting the first barrel  2  is not limited to a specific material, it is preferable to use a material which is generally used for syringes, which is optically transparent and which has a grass transition point or a melting point of 110° C. or higher, for example, polypropylene, polymethylpentene, polyolefin like cyclic polyolefin, polyethylene terephthalate, polyethylene naphthalate, amorphous polyarylate, etc. Cyclic polyolefin is especially desirable in view of a high transparency, a high steam sterilization property and a good medical agent non-absorption property. 
         [0022]    The first barrel  2  is integrally formed by one of the aforementioned various types of synthetic resins using injection-molding so that a flange  2 A is formed at the rear end portion. Similarly, the second barrel  4  is integrally formed by one of the aforementioned various synthetic resins using injection-molding so that a flange  4 A is formed at the rear end portion. The first barrel  2  and the second barrel  4  may be formed by either an identical synthetic resin or a similar type of synthetic resin (hereinafter, called as a similar type of synthetic resin) or different synthetic resins or different types of synthetic resins (hereinafter, called as different types of synthetic resins). 
         [0023]    Here, as shown in  FIGS. 2 and 3 , a connecting tube portion  2 B is formed at the tip portion of the first barrel  2 , and a male screw  2 C is formed on the outer periphery of the connecting tube portion  2 B. The male screw  2 C is constituted as a trapezoidal screw with a large lead angle and a less winding number. An inner tapered surface  2 D is formed on the inner periphery of the connecting tube portion  2 B. The inner tapered surface  2 D has a taper angle in a range between 6% and 12%, preferably in a range between 6% and 10%. 
         [0024]    In general, nozzles of commercially supplied injectors have a taper (which corresponds to the outer tapered surface  4 E according to the present invention) of about 6% usually. Therefore, it is preferable to set the taper angle of the inner tapered surface  2 D to 6% because it is possible to connect a commercially supplied injector to the first barrel according to the present invention. In this case, the male screw  2 C needs to have a shape and size which is suitable to screw together with a commercially supplied injector. Additionally, it is preferable to set the taper angle of the inner tapered surface  2 D to a range between 6% and 10% as described above because it is possible to use a commercially supplied injector and the second barrel designed according to the present invention as well. 
         [0025]    Alternatively, it is effective in some applications to intentionally set the taper angle of the inner tapered surface  2 D to an angle for which a commercially supplied injector cannot be used. 
         [0026]    On the other hand, as shown in  FIGS. 4 and 5 , a nozzle portion  4 C having a center hole  4 B is formed at the tip portion of the second barrel  4 , and a screw tube portion  4 D is formed at the external side of the nozzle portion  4 C in a concentric fashion. 
         [0027]    An outer tapered surface  4 E is formed on the outer periphery of the nozzle portion  4 C. The outer tapered surface  4 E has the aforementioned taper angle and fits tightly and smoothly to the inner tapered surface  2 D on the inner periphery of the connecting tube portion  2 B. A female screw  4 F is formed on the inner periphery of the screw tube portion  4 D. The female screw  4 F is screwed together with the male screw  2 C on the outer surface of the connecting tube portion  2 B in a freely removable manner. It is preferable to arrange so that the taper angle of the inner tapered surface  2 D and that of the outer tapered surface  4 E are concerted in view of a good sealing performance, however they do not need to be concerted always as described above. 
         [0028]    Either one of the surface of the male screw  2 C of the connecting tube portion  2 B of the first barrel  2  and the surface of the female screw  4 F of the screw tube portion  4 D of the second barrel  4  is roughened to a predetermined surface roughness. In this embodiment, the surface of the female screw  4 F of the screw tube portion  4 D of the second barrel  4  is not roughened, whereas the surface of the male screw  2 C and the outer periphery of the connecting tube portion  2 B of the first barrel  2  shown in  FIG. 6  are roughened to a surface roughness in a range between Ra1.0 and Ra2.0. 
         [0029]    Additionally, it is constituted so that the tip portion of the nozzle portion  4 C of the second barrel  4  is positioned in the connection tube portion  2 B of the first barrel  1  in a condition that the inner tapered surface  2 D of the connecting tube portion  2 B of the first barrel  2  and the outer tapered surface  4 E of the nozzle portion  4 C of the second barrel  4  are in a taper-fitted condition (see  FIG. 8 ). 
         [0030]    In a syringe kit for mixing two medicinal chemicals according to one embodiment as described above, for example, when the medicinal chemical A in the first barrel  2  is mixed with the medicinal chemical B in the second barrel  4 , the male screw  2 C on the outer periphery of the connecting tube portion  2 B of the first barrel  2  and the female screw  4 F on the inner periphery of the screw tube portion  4 D of the second barrel  4  shown in  FIG. 1  are screwed together, and the inner tapered surface  2 D on the inner periphery of the connecting tube portion  2 B of the first barrel  2  and the outer tapered surface  4 E on the outer periphery of the nozzle portion  4 C of the second barrel  4  are taper-fitted (see  FIG. 7 ). 
         [0031]    During the operation, because either the surface of the male screw  2 C and the outer periphery of the connecting tube portion  2 B of the first barrel  2  or the surface of the female screw  4 F and the inner periphery of the screw tube portion  4 D of the second barrel  4  or both of them (in this embodiment, the surface of the male screw  2 C of the connecting tube portion  2 B of the first barrel  2 ) is roughened to a surface roughness in a range between Ra1.0 and Ra2.0, stick and slip phenomena are prevented. Additionally, it is preferable in view of a secured sealing performance to roughen neither the inner tapered surface  2 D on the inner periphery of the connecting tube portion  2 B of the first barrel  2  nor the outer tapered surface  4 E of the nozzle portion  4 C of the second barrel  4 . 
         [0032]    Therefore, in a syringe kit for mixing two medicinal chemicals according to one embodiment, it is possible to prevent slip and slip phenomena which tend to occur when the male screw  2 C on the outer periphery of the connecting tube portion  2 B of the first barrel  2  and the female screw  4 F on the inner periphery of the screw tube portion  4 D of the second barrel  4  are screwed together or they are released from a screwed condition, and thus it is possible to ensure a smooth and steady operation. 
         [0033]    Additionally, in a syringe kit for mixing two medicinal chemicals according to one embodiment, the tip portion of the nozzle portion  4 C of the second barrel  4  is positioned in the connecting tube portion  2 B of the first barrel  2  in a condition that the inner tapered surface  2 D on the inner periphery of the connecting tube portion  2 B of the first barrel  2  and the outer tapered surface  4 E on the outer periphery of the nozzle portion  4 C of the second barrel  4  are taper-fitted (see  FIG. 8 ). Thus, in a condition that the connecting tube portion  2 B of the first barrel  2  is connected to the screw tube portion  4 D of the second barrel  4  as shown in  FIG. 7 , the gasket of the first plunger  1  of the first barrel  2  can slide in the first barrel  2  with a sufficient stroke. As a result, it is possible to sufficiently and certainly mix the medicinal chemical A in the first barrel  2  with the medicinal chemical B in the second barrel  4 . 
         [0034]    A syringe kit for mixing two medicinal chemicals according to the present invention is not limited to the aforementioned embodiment. For example, it is possible to roughen only the surface of the female screw  4 F and the inner periphery of the screw tube portion  4 D of the second barrel  4  to a surface roughness in a range between Ra1.0 and Ra2.0 while the surface of the male screw  2 C and the outer periphery of the screw tube portion  4 D of the second barrel  4  are not roughened. It is also possible to roughen both the surface of the male screw  2 C and the outer periphery of the connecting tube portion  2 B of the first barrel  2  and the surface of the female screw  4 F and the inner periphery of the screw tube portion  4 D of the second barrel  4 . The most preferable embodiment is to roughen only the surface of the male screw  2 C and the outer periphery of the connecting tube portion  2 B of the first barrel  2 . This embodiment can be used as a commercially supplied injector. 
         [0035]    It is also possible to change the surface roughness for roughening within a range between Ra1.0 and Ra2.0 depending upon the type of synthetic resin which constitutes the first barrel  2  or the second barrel  4 . By setting the surface roughness to this range, it successfully prevent stick and slip phenomena even when the first barrel  2  and the second barrel  4  are formed by either a same type of synthetic resin or different types of synthetic resins. It is impossible to effectively prevent stick and slip phenomena by using synthetic resins which is generally used for syringes if the surface roughness is less than Ra1.0. The screwed connection may be loosened because of a decreased screwed connection resistance during the mixing operation if the surface roughness is higher than Ra2.0. 
       EXPLANATION OF THE REFERENCE NUMBERS 
       [0000]    
       
           1 : first plunger 
           1 A: end plate 
           2 : first barrel 
           2 A: flange 
           2 B: connection tube portion 
           2 C: male screw 
           2 D: inner tapered surface 
           3 : second plunger 
           3 A: end plate 
           4 : second barrel 
           4 A: flange 
           4 B: center hole 
           4 C: nozzle portion 
           4 D: screw tube portion 
           4 E: outer tapered surface 
           4 F: female screw