Abstract:
Disclosed is a coating die which can recover a coating solution to be wasted in a good manner, while suppressing adhesion of foreign matter onto an object to be coated. A coating apparatus comprising the coating die is also disclosed. Specifically disclosed is a coating die ( 30 ) for coating a web ( 2 ) with a paste ( 3 ), which comprises a main body ( 31 ) having a discharge opening ( 31   e ) for discharging the paste ( 3 ) upwardly, a recovery pan ( 32   c ) for recovering the paste ( 3 ) flowing out from the discharge opening ( 31   e ), and flow passage (grooves ( 32   a,    32   a ) and shoots ( 32   b,    32   b )) which are integrally formed with the main body ( 31 ) for the purpose of guiding the paste ( 3 ) from the discharge opening ( 31   e ) to the recovery pan ( 32   c ).

Description:
TECHNICAL FIELD 
     The present invention relates to a coating die and a coating apparatus with the coating die. 
     BACKGROUND ART 
     As to a conventional coating apparatus that has a coating die for coating a coating solution (paste) on a sheet (web), it is common way to fill up the paste in the discharge path of the coating die in order to remove air from the path, before coating with the coating die. If this deaeration process is not completely done, the paste contains the air and there are bubbles in the coated surface, thereby leading the coating defect. 
     When filling up the paste and removing the air, the paste is continuously discharged and the paste flows down from the discharge opening of the coating die. If the paste flows into the other devices located around the die, the paste may cause the failure thereof. If the paste is dried off around the discharge opening of the die, the dried-out paste may be attached to the web as a foreign matter and lead the coating defect. 
     Especially if the web (object to be coated) is an electrode web used in a battery, a foreign matter would be contained in the battery, and may occur defects such as an internal short-circuit. 
     To solve the above-mentioned problems, it is required for the coating apparatus to provide a good recovery of the paste that is flowed down when filling up the paste and deaerating for the ready-to-coat. 
     For instance, JP 2003-88791 A discloses a coating apparatus which has a nozzle for coating and the nozzle is connected with a paste storage via a capillary passage, and in which the paste storage has an opening in the vicinity of discharge openings of the nozzle. Due to the structure, the paste flowed down from the discharge openings can be recovered by the storage. 
     However, the coating apparatus of JP 2003-88791 A uses the capillary action for coating, so that the fine adjustment of the coating condition, such as the distance between the nozzle and the web or the discharging volume, is difficult and therefore the coating defect may be easily occurred. Especially, in such a case that the thin and even paste layer needs to be formed on the web, the fine adjustment is important. Thus, there is a limit to use the technique disclosed in JP 2003-88791 A. 
     Further, the paste discharged from the discharge openings is recovered to the paste storage, which can improve the usability of the paste, but the foreign matter (grit and dust) may be mixed in the paste during the recirculation. When the paste is coated on the electrode web of the battery, the foreign matter occurs the defect, so that the coating solution is preferably recovered as the waste, or recovered and processed for reuse, whereby the technique of JP 2003-88791 A is not applicable. 
     Citation List 
     Patent Literature 
     PTL 1: JP 2003-88791 A 
     SUMMARY OF INVENTION 
     Technical Problem 
     The objective of the present invention is to provide an unexpected coating die and a coating apparatus containing the coating die, which is capable of recovering a coating solution to be wasted and of preventing foreign matter from attaching to an object to be coated. 
     Technical Solution 
     The first aspect of the present invention is a coating die for coating an object to be coated with a coating solution. The coating die includes: a main body having a discharge opening for discharging the coating solution upwardly; a recovery container for recovering the coating solution flowed down from the discharge opening; and a flow passage formed integrally with the main body, guiding the coating solution to the recovery container. 
     In the advantageous embodiment of the present invention, the flow passage includes: a groove having a bottom, formed around the discharge opening, inclined toward a predetermined position; and a shoot having a bottom, formed continuously from the groove, discharging the coating solution guided along the groove to outside of the groove. 
     In the preferable embodiment of the present invention, the coating die further includes adjusting means for adjusting a distance between the discharge opening of the main body and the object to be coated. 
     The second aspect of the present invention is a coating apparatus including the coating die of the first aspect of the coating die. The coating apparatus includes: a conveyor for conveying the object to be coated continuously, with the surface thereof facing to the discharge opening of the coating die; and a supporter for supporting the coating die movable within a state where the coating die faces to the surface of the object to be coated and a state where the coating die is separated from the object to be coated. 
     Advantageous Effects of Invention 
     According to the first and second aspect of the present invention, it is provided that the coating die and the coating apparatus, both of which are capable of recovering the coating solution to be wasted and of preventing foreign matter from attaching to the object to be coated. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG. 1  is a perspective view of a coating apparatus. 
         FIG. 2  shows a “separated position” of coating dies. 
         FIG. 3  shows a “coating position” of the coating dies. 
         FIG. 4  depicts an enlarged perspective view of the coating die. 
         FIG. 5  is a section view illustrating a discharge path in the coating die. 
         FIG. 6  illustrates a schematic view of a feeding path of a coating solution. 
         FIG. 7  illustrates a flow of the coating solution in the coating die. 
         FIG. 8  illustrates a schematic view of another embodiment of the coating apparatus. 
     
    
    
     REFERENCE SIGNS LIST 
       1 : coating apparatus 
       2 : web (object to be coated) 
       3 : paste (coating solution) 
       10 : back-up roller (conveyor) 
       20 : support table (supporter) 
       30 : coating die 
       31 : main body 
       31   e:  discharge opening 
       32   a:  groove (flow passage) 
       32   b:  shoot (flow passage) 
       32   c:  recovery pan (recovery container) 
       33 : elevator device (adjusting means) 
     DESCRIPTION OF EMBODIMENTS 
     Referring to  FIGS. 1 to 6 , the structure of a coating apparatus  1  is described. For convenience of explanation, a front-back direction, a right-left direction and an upper-lower direction are defined by the X-arrow, the Y-arrow and the Z-arrow in  FIG. 1  directing the front, right and upper, respectively. 
     The coating apparatus  1  is used for coating a paste  3  on the surface (to be coated) of a web  2  that is an object to be coated. 
     The web  2  is a sheet member such as a paper, a plastic film, a metal foil, a rubber sheet or a textile, and is continuously conveyed to the coating apparatus  1  with a conveyor. In this embodiment, the web  2  is an electrode web (metal foil) of a battery. 
     The paste  3  is an oil-based or a water-based solution to be coated on the web  2 . In this embodiment, the paste  3  is an electrode compound paste containing electrode active materials. 
     As depicted in  FIG. 1 , the coating apparatus  1  includes a back-up roller  10 , a support table  20  and multiple coating dies  30 . 
     As to the coating apparatus  1 , the back-up roller  10  conveys the web  2  continuously, and the three coating dies  30  mounted on the support table  20  apply the paste  3  on the web  2  in three stripes. 
     The back-up roller  10  continuously conveys the web  2  in a predetermined conveying direction (the arrow A direction in drawings) that is wound off from a roll (not shown), and the roller gives a predetermined tension (so that the web  2  is not wound down). 
     As shown in  FIG. 1 , the roller  10  supports the back surface of the web  2  (opposite surface to the surface to be coated), and conveys the web  2  with the surface to be coated faced to the coating dies  30 . The roller  10  is rotated at a predetermined speed, so that the web  2  is conveyed in the rotation direction of the roller  10 . 
     The support table  20  supports the back-up roller  10  rotatably, and includes a rotation device  21  for driving the roller  10  and a sliding device  22  for supporting and moving the coating dies  30 . 
     As shown in  FIG. 1 , the rotation device  21  includes supporters  21   a  for supporting the back-up roller  10  and an electric motor  21   b  for rotating the roller  10 . 
     The supporter  21   a  contains a bearing, which rotatably supports the shaft of the roller  10 . 
     The electric motor  21   b  is configured as the high-accurately controlled motor, and the output shaft thereof is connected to the shaft of the roller  10 . The motor  21   b  drives the roller  10  at the predetermined speed. The motor  21   b  is disposed at one of the supporters  21   a.    
     Thus, the roller  10  is supported by the supporters  21   a  and driven by the motor  21   b,  and the roller is rotated at the predetermined speed. 
     As shown in  FIG. 1 , the sliding device  22  supports and locates the coating dies  30  at a set position in the front-back direction (that is the direction perpendicular to the shaft of the back-up roller  10 ). 
     More specifically, the sliding device  22  includes sliding guides  22   a  aligned in the front-back direction and a driving device for driving the sliding device  22  so as to move the coating dies along the sliding guides  22   a.    
     As shown in  FIG. 1 , the coating dies  30  are aligned in the left-right direction (that is the shaft direction of the back-up roller  10 ), spaced at a predetermined interval each other, and the coating dies move integrally. 
     Thus, the coating dies  30  are movable in the one plane direction (front-back direction) by predetermined distance, especially, as shown in  FIGS. 2 and 3 , the dies are movable between the position (hereinafter “separated position”) separated from the roller  10  where is easy to clean or attach/detach the coating dies  30  and the position (hereinafter “coating position”) below the roller  10  with facing the circumferential direction of the roller  10 . 
     As depicted in  FIG. 4 , the coating die  30  includes a main body  31  discharging the paste  3  upwardly, recovery parts  32  for recovering the paste  3  to be flowed down from the main body  31  and an elevator device  33  for moving the main body  31  in the upper-lower direction. The coating die  30  discharges the paste  3  in the upper direction. 
     As illustrated in  FIGS. 4 to 6 , the main body  31  has a manifold  31   b  storing the paste  3  contemporarily and a discharge opening  31   e  for upwardly discharging the paste  3  stored in the manifold  31   b.    
     The main body  31  includes a feeding path  31   a  connected with the manifold  31   b,  the manifold  31   b  storing the paste  3  fed into the main body  31 , a slit  31   c  configured as a part of the discharge path of the main body  31  for discharging the paste  3 , and a lip  31   d  arranged at the tip of the main body  31  for forming the discharge opening  31   e.    
     The feeding path  31   a  is a passage communicating the inside to the outside of the main body  31 , and is formed from the outer face of the main body  31  to the manifold  31   b  disposed inside thereof. The feeding path  31   a  is connected to a pump  34   a,  a valve  34   b,  and a tank  34   c,  both of which are the feeding sources of the paste  3  (see  FIG. 6 ), and the paste  3  is fed into the main body  31  through the feeding path  31   a.    
     The manifold  31   b  is formed inside of the main body  31  as the space that has the same width as the width in the left-right direction (coating width) of the discharge opening  31   e,  and connected with the one end (that is disposed inside the main body  31 ) of the feeding path  31   a.  The manifold  31   b  contemporarily stores the paste  3  fed into the main body  31 , and in the manifold, the paste  3  fed through the feeding path  31   a  is broadened in the left-right direction in the main body  31 . 
     The slit  31   c  is a space defined inside the main body  31 , and formed upward from the manifold  31   b.  The slit  31   c  has the same width as the manifold  31   b  has, and guides the paste  3  that is stored and broadened in the left-right direction in the manifold  31   b  to the discharge opening  31   e.    
     The lip  31   d  is formed at the end (upper end) of the main body  31 , and has the discharge opening  31   e  which is opening upward. The discharge opening  31   e  has the same width as the manifold  31   b  and the slit  31   c  have, and disposed at the upper end of the slit  31   c.  The structure of the discharge opening  31   e  is an important matter to the coating quality, so that the opening area of the discharge opening  31   e  is rigorously adjusted in accordance with the coating configuration of the coating apparatus  1 . 
     It should be mentioned that the feeding path  31   a  is arranged in the lower area of the main body  31  and opens at the center in the left-right direction. Thus, the paste is broadened evenly in the left-right direction (longitudinal direction of the coating area) inside the manifold  31   b.    
     The manifold  31   b  is apart from the discharge opening  31   e.  Therefore, the evenness of the paste  3  is maintained that travels from the manifold  31   b  to the discharge opening  31   e  via the slit  31   c.    
     The discharge opening  31   e  is opening upward. This structure prevents air from mixing into the paste  3  when coating it. 
     As illustrated in  FIG. 6 , the end (outer end of the main body  31 ) of the feeding path  31   a  is connected to the tank  34   c  storing the paste  3  through the pump  34   a  for feeding the paste  3  to the main body  31  and the valve  34   b  for adjusting the feeding volume of the paste  3 , and the other end of the feeding path  31   a  is connected to the manifold  31   b.    
     The valve  34   b  is a conventional on-off valve, and the pump  34   a  is a conventional metering pump. These valve  34   b  and the pump  34   a  are controlled with high accuracy by a controller. For example, the discharge volume of the pump  34   a  is controlled in response to the rotation speed of the back-up roller  10 , thereby adjusting the coating thickness of the paste  3  fed from the pump  34   a  on the web  2 . 
     In the coating die  30 , the feeding passage is configured in the following order: the tank  34   c,  the pump  34   a,  the valve  34   b,  the manifold  31   b,  the slit  31   c,  and the discharge opening  31   e.  The paste  3  is fed along the feeding passage at the predetermined volume in the predetermined time. Thus, the paste  3  contemporarily stored in the manifold  31   b  is discharged from the discharge opening  31   e  of the lip  31   d.    
     As illustrated in  FIGS. 4 and 5 , the lip  31   d  is formed such that the tip thereof is projected upward, and the discharge opening  31   e  is disposed at the tip. The lip includes top surfaces  31   f  defining the discharge opening  31   e  and inclined surfaces  31   g  continuously connected to the top surfaces  31   f.  The paste  3  flowed out from the discharge opening  31   e  drips down along the top surfaces  31   f  and the inclined surfaces  31   g.    
     As depicted in  FIG. 4 , the recovery parts  32  are attached to the main body  31  that are arranged symmetry with respect to the discharge opening  31   e,  and recovery the paste  3  flowed out from the discharge opening  31   e  of the main body  31 . 
     The recovery part  32  includes a groove  32   a  for collecting the paste  3  to a predetermined portion, a shoot  32   b  for discharging the paste  3  collected by the groove  32   a  and a recovery pan  32   c  for recovering the paste  3  discharged through the shoot  32   b.    
     The grooves  32   a  are configured in the upper portion of the lip  31   d  (namely, to surround the periphery of the discharge opening  31   e ) and configured as the flow passages having bottoms inclined downwardly toward a predetermined position (apart from the feeding path  31   a  in plan view). The groove  32   a  has inclined faces, which are formed at the both ends in the front-back direction of the discharge opening  31   e  and continued from the bottom of the inclined surface  31   g  of the lip  31   d,  and has inclined faces, which are formed at the both ends in the left-right direction of the discharge opening  31   e  and extended toward the left-right direction from the discharge opening  31   e.  The grooves  32   a  are formed at the both sides in the front-back direction of the top surface of the main body  31 , and the groove has the shape inclined toward the middle portion in the left-right direction oriented by a predetermined distance to the one side of the left or right side (in this embodiment, right side). 
     The shoots  32   b  are the flow passages having bottoms to discharge the paste  3  guided along the grooves  32   a  to the outside of the grooves  32   a.  The groove  32   a  inclined downward has an opening  32   d  at the bottom end to communicate the inside of the groove  32   a  with the outside, and the bottom of the shoot  32   b  is connected continuously to the bottom of the groove  32   a  via the opening  32   d.  The shoot  32   b  is extended outward of the main body  31  from the opening  32   d.  The shoot  32   b  is inclined downwardly toward the outer end thereof. 
     The recovery pan  32   c  is a container having an enough volume and disposed below the outer end of the shoot  32   b.  The recovery pan  32   c  receives the paste  3  flowed down through the groove  32   a  and the shoot  32   b  with the action of gravity. The recovery pan  32   c  is mounted on the elevator device  33 . 
     As described above, in the coating die  30 , the paste  3  flowing out from the discharge opening  31   e  goes along the inclined grooves  32   a  and is guided to the shoots  32   b,  whereby the paste drops through the shoots  32   b  into the recovery pans  32   c  and is recovered (referring to  FIG. 7 ). 
     The paste  3  thus recovered in the recovery pans  32   c  is wasted or reused after processing for reuse. 
     As shown in  FIGS. 3 and 4 , the elevator device  33  keeps the main body  31  horizontal and positions the main body  31  at a predetermined location in the upper-lower direction. 
     The elevator device  33  supports the main body  31  and the recovery parts  32  directly or indirectly. The elevator devices  33  are detachably mounted on the sliding device  22 , which are spaced by a predetermined distance each other. The elevator device  33  has an actuator that is controlled with high accuracy, and the location of the main body  31  (namely, the location of the discharge opening  31   e ) in the upper-lower direction is highly accurately decided with the actuator. 
     Thus, in each elevator device  33 , the actuator is operated when the coating die  30  is located in “coating position”, so that each coating die  30  can perform fine positioning of the distance between the discharge opening  31   e  of the main body  31  and the back-up roller  10  (that is the distance between the discharge opening  31   e  and the web  2 ). Therefore, the coating apparatus  1  provides the stable coating quality. 
     Referring to  FIG. 7 , preparation process for the coating die  30  when starting the coating with the coating apparatus  1  is described. In this time, each coating die  30  is located in the coating position. 
     Before coating (in an initial state), the paste  3  is not filled in the feeding passage of the coating die  30  (referring to  FIG. 6 , the passage through the tank  34   c,  the pump  34   a,  the valve  34   b,  the manifold  31   b,  the slit  31   c  and the discharge opening  31   e ). So, in the preparation process before coating in order to prevent the air from mixing in the paste  3 , the paste  3  is filled up in the feeding passage to deaerate. 
     When filling up the paste  3  and deaerating, the paste  3  is continuously discharged from the discharge opening  31   e,  and the paste  3  is dripped down from the discharge opening  31   e  of the lip  31   d.    
     As illustrated in  FIG. 7 , the paste  3  flowing down from the discharge opening  31   e  runs along the top surfaces  31   f  and the inclined surfaces  31   g  to the grooves  32   a.  The paste  3  flowed to the grooves  32   a  is collected in the recovery pans  32   c  via the shoots  32   b.    
     The coating die  30  includes the main body  31  discharging the paste  3 , the recovery pans  32   c  for recovering the paste  3  flowed down from the discharge opening  31   e  of the main body  31 , the grooves  32   a  and the shoots  32   b  as the guides for the paste  3  through the recovery pans  32   c.    
     This structure provides the good recovery for the paste  3  that is flowed down from the discharge opening  31  e during the preparation process. Further, the paste  3  is prevented from attaching to the peripheral members of the coating dies  30  of the coating apparatus  1 , and therefore the web  2  is prevented from suffering from the foreign matter. Thus, the coating apparatus  1  maintains the good coating quality, and the peripheral members are prevented from damage. 
     Moreover, in the case that the paste  3  is attached to the any portion of the coating dies  30  and dried off, the coating dies  30  are moved to the separated position from the coating position by using the sliding device  22  and the coating dies can be cleaned and washed independently, thereby improving the efficiency of cleaning. In other words, the cleaning efficiencies for the coating dies  30  are enhanced. 
     Especially in the case that the web  2  is the electrode web of the battery, the foreign matter attached around the discharge opening  31   e  of the coating die  30  is prevented from mixing into the paste. Therefore, it is possible to maintain the product quality of the battery including the web  2  coated with the paste  3  that is the electrode compound. 
     In each coating die  30 , the distance between the discharge opening  31   e  and the back-up roller  10  is adjustable by using the elevator device  33 , and therefore, the coating die  30  is easy to fine adjust the position thereof and it is easy to maintain the evenness of the coating thickness of the paste  3 . Especially in the coating apparatus  1  containing multiple coating dies  30 , it is easy to adjust the coating condition of the paste  3  in each coating die  30 , so that the high coating performance is stably obtained. 
     Further, each coating die  30  has the recovery equipment, that is, the main body  31  is installed with the recovery parts  32 , so that there is no need to prepare a separate recovery device for the paste  3  flowed down from the discharge opening  31   e.    
     It should be noted that the web  2  is not limited to the electrode web and the web may be a common object to be coated, and the paste  3  is not limited to the electrode compound and the paste may be a common coating solution. 
     In this embodiment, the coating apparatus  1  includes three coating dies  30 , but the number or the coating width of the coating die  30  may be changeable in accordance with the coating condition for the web  2 . 
     The sliding device  22  moving the coating dies  30  in the front-back direction is used to move the coating dies  30  integrally, but the sliding device may move them separately. In the case, the each sliding guide  22   a  has the driving device for actuating the sliding device. 
     The coating dies  30  are arranged in the circumferential direction of the back-up roller  10 , and the discharge direction through the discharge opening  31   e  of the coating die  30  is set as the radius direction of the back-up roller  10 . The coating dies  30  and the back-up roller  10  may be set in the arrangement shown in  FIG. 8 . 
     In the arrangement shown in  FIG. 8 , the coating dies  30  discharge the paste  3  in the obliquely upward. In this embodiment, the sliding device  22  moves the coating dies  30  such that the coating dies are close to or separated from the back-up roller  10 , and the elevator devices  33  elevate the coating dies  30  such that the distance between the discharge openings  31   e  of the coating dies and the surface of the web  2  is adjustable. 
     The recovery parts  32  may be disposed at least in one side where gravity acts on the paste  3  discharged from the discharge opening  31   e  (namely, in the lower side), and in the embodiment shown in  FIG. 8 , the recovery parts may be provided only lower side, which makes the number of members reduced. 
     Industrial Applicability 
     The present invention is applicable to a coating apparatus for coating a coating solution on a surface of a sheet member, and especially to a technique of recovering the coating solution flowed out during a preparation step.