JP2010021203A - Apparatus for manufacturing electrode for electric double layer capacitor - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To achieve a manufacturing apparatus capable of mass-producing an electrode for an electric double layer capacitor having large capacity, low resistance and excellent in long-term durability with high yield and at a high speed. <P>SOLUTION: On the circumferential surface of a gravure roll 4, a groove is formed in an inclined direction for a rotating axis X, viewed from a direction vertical to the rotating axis X. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  TECHNICAL FIELD The present invention relates to an apparatus for manufacturing an electrode for an electric double layer capacitor having a mechanism for bonding a sheet electrode to an aluminum foil, and an apparatus and a material for applying a conductive adhesive to a current collector continuously and at high speed. Is related to the technology.

  Electric double layer capacitors are used for power supplies for instantaneous voltage drop protection devices, auxiliary power supplies for electric vehicles and forklifts, etc. because of their large capacity compared to electrolytic capacitors and high output compared to secondary batteries. Yes.

  The electrode for an electric double layer capacitor is formed by closely adhering an electrode mixture obtained by kneading a carbon material having a high specific surface area such as activated carbon, a conductive filler such as carbon black, and a binder resin to a current collector. As the current collector, a metal foil or a metal plate such as aluminum, nickel, and stainless steel is used.

  As a method for producing an electrode for an electric double layer capacitor, a method of integrating a current collector and a polarizable electrode (hereinafter referred to as a carbon sheet) formed by molding the electrode mixture as described above into a sheet (sheet method) ) And a method (coating method) of applying (applying) an ink-like electrode mixture to a current collector.

  In addition, the sheet method includes a method of bonding the carbon sheet and the current collector through a conductive adhesive and a method of pressure bonding the carbon sheet to the current collector, but in order to reduce the contact resistance, A method using a conductive adhesive has become the mainstream.

  The electric double layer capacitor is manufactured through the following process. First, an electrode manufactured by any one of a sheet method and a coating method and a separator are laminated. Alternatively, the electrode and the separator are wound. Next, the electrolytic solution is impregnated with the laminated or wound one. And what was impregnated with electrolyte solution is stored in an exterior material, and an electric double layer capacitor is completed. As an exterior material, there are an aluminum laminated film and a metal can, which are selected according to the use environment of the electric double layer capacitor.

  In general, an electrode manufactured by a coating method can be made thinner than an electrode manufactured by a sheet method. In addition, an electrode manufactured by a coating method is less expensive to manufacture than an electrode manufactured by a sheet method. For this reason, it is suitable for use in manufacturing a low resistance / high output electric double layer capacitor and when mass production of the electric double layer capacitor is required.

  On the other hand, the electrode manufactured by the coating method has a problem that the carbon material in the electrode is easily dropped, which causes an internal short circuit and performance deterioration and lacks reliability from the viewpoint of long-term stability of the product.

  Therefore, when manufacturing an electric double layer capacitor having a high energy density, or when emphasizing the long-term reliability of the electric double layer capacitor, there is a tendency to manufacture an electrode by a sheet method. In electrode production by the sheet method, a process for producing a carbon sheet composed of a carbon material and a binder such as a resin binder, a conductive adhesive is applied to an aluminum foil, and the carbon sheet is bonded to the coated part. Process. In the above bonding process, it is possible to apply a thin conductive adhesive with a thickness of several μm on the aluminum foil to increase the capacity, lower resistance, higher output, and lower cost of the electric double layer capacitor. It has become an important issue in realizing.

  In the production of an electrode by the sheet method, several production methods have been proposed so far. Among them, there is a method of applying a conductive adhesive by a roll coater. Patent Document 1 has a description that it can be manufactured by a roll coater as a conductive adhesive coating apparatus in the sheet method.

  In Patent Document 2, a backup roll is provided on a gravure roll having a grid-like cell pattern, and a conductive adhesive is applied to a current collector to a thickness of 10 μm or less using a direct gravure method. Techniques for monitoring coating failures have been proposed.

  Furthermore, in the example of Patent Document 3, a conductive adhesive made of graphite and PTFE is applied to an etched hard aluminum foil using a gravure coater, and a carbon sheet is attached to the applied portion. The method of combining is described.

Patent Document 4 describes that it is preferable to use a flexible soft aluminum foil because an electrode using the flexible aluminum foil does not cause an accident that the electrode breaks when laminated or wound. Has been.
Japanese Patent Laid-Open No. 11-162787 (released on June 18, 1999) Patent No. 3811122 (registered on June 2, 2006) Japanese Unexamined Patent Publication No. 2006-1000047 (published on April 13, 2006) Patent No. 3692735 (registered on July 1, 2005)

  As mentioned above, in the process of producing high-performance, low-cost electric double layer capacitor electrodes, the technology that uses a gravure coater as a device for continuously applying a thin film of conductive adhesive to aluminum foil It is known. In addition, it is known that a soft aluminum foil is preferred and used because it is easy to handle in the lamination process or winding process of the electrode. However, a technique for mass-producing bonded electrodes using a conductive adhesive at a high speed with a high yield is not yet known.

  When manufacturing the electrode for electric double layer capacitors by the sheet method, the number of steps is overwhelmingly large compared to the coating method, and there is a problem that the cost is increased because a separate conductive adhesive is required. In order to reduce the manufacturing cost of the electrode, as described in Patent Documents 1 to 3, it has been attempted to apply a gravure coater that can be applied with a thin film and has a relatively high coating speed. . However, the application of the conductive adhesive by the conventional gravure coater has the following problems.

  According to Patent Document 1, an optimum model such as a roll coater can be selected for a conductive adhesive coating apparatus depending on the viscosity and thickness of the adhesive and the coating temperature. However, in practice, it is extremely difficult to select a coating device that can mass-produce electrodes for electric double layer capacitors with excellent performance only with the properties of the conductive adhesive, the desired coating thickness, and the manufacturing environment. Have difficulty.

  In Patent Document 2, as a conductive adhesive coating method, a direct gravure method in which a backup roll is provided on a gravure roll, a current collector foil is fixed between the rolls, and the conductive adhesive is printed is used. However, in the direct gravure method, since the printing pressure may be excessively large with respect to the aluminum foil as a bonding substrate, the current collector may be damaged by friction with the gravure roll.

  Also, in the direct gravure method, the aluminum foil is pressed and fixed between the gravure roll and the backup roll, so the tensile stress increases with respect to the aluminum foil, with the base point between these two rolls. The current collector may be deformed or broken.

  Furthermore, Patent Document 3 describes that a conductive adhesive composed of graphite and PTFE is applied to a hard aluminum foil with a gravure coater. However, the technology for mass production at high speed is not mentioned at all, and the adhesion between the hard aluminum foil and the carbon sheet is not good.

  And when a flexible soft aluminum foil is used like patent document 4, since a soft aluminum foil does not have a waist and tensile strength is small, it will be damaged by the stress which arises in the process of applying a conductive adhesive. There is a risk of deformation or breakage.

  The present invention has been made in view of the above-described conventional problems, and its purpose is to manufacture a high-capacity, low-resistance, and electric double-layer capacitor electrode that is excellent in long-term durability with high yield and high-speed production. It is to realize the device.

  In order to solve the above problems, an apparatus for producing an electrode for an electric double layer capacitor according to the present invention includes a gravure roll for applying a conductive adhesive to a current collector by a kiss coating method, and an active material that is a carbon material, a conductive material. In the electric double layer capacitor electrode manufacturing apparatus in which a carbon sheet containing a conductive filler and a binder imparting properties is bonded to the current collector via the conductive adhesive, on the peripheral surface of the gravure roll, A groove is formed along an oblique direction with respect to the rotation axis when viewed from a direction perpendicular to the rotation axis.

  According to the invention, the conductive adhesive filled in the groove constantly flows in the groove on the peripheral surface of the rotating gravure roll, and the fluid is transferred to the current collector. At this time, bubbles and aggregates in the conductive adhesive flow through the groove and slide out along the groove. Therefore, the conductive adhesive adheres to the contact surface between the current collector and the gravure roll. Only the agent remains. Therefore, since the conductive adhesive can be applied efficiently, transfer efficiency is improved. As a result, it is possible to prevent poor coating of the conductive adhesive and to improve the yield. Therefore, it is possible to mass-produce high-capacity, low-resistance electric double layer capacitor electrodes with high yield and high speed, and to reduce the manufacturing cost of the electrodes.

  In addition, since it is possible to increase the adhesive strength at the interface between the current collector and the conductive adhesive, it is possible to manufacture an electrode for an electric double layer capacitor that is excellent in long-term durability.

  In the electric double layer capacitor electrode manufacturing apparatus, the current collector may be a hard aluminum foil that is not annealed.

  Thereby, even if a large stress is applied to the hard aluminum foil, no wrinkles are formed, and the hard aluminum foil is not stretched and deformed. Due to this property, when the hard aluminum foil is used as the current collector, it is possible to prevent defects and accidents in which the manufactured bonded electrode is deformed.

  In any one of the electric double layer capacitor electrode manufacturing apparatuses, the gravure roll may rotate in a direction opposite to a traveling direction of the current collector.

  Thereby, a liquid pool called a transfer bead is formed between the current collector and the gravure roll, and the liquid pool continuously supplies the conductive adhesive to the current collector. It is possible to prevent a defect that a portion where the conductive adhesive is not applied is generated.

  As described above, the apparatus for manufacturing an electrode for an electric double layer capacitor according to the present invention has grooves along the oblique direction with respect to the rotation axis when viewed from the direction perpendicular to the rotation axis of the gravure roll. Is formed.

  Therefore, there is an effect of realizing a manufacturing apparatus capable of mass-producing an electrode for an electric double layer capacitor having a large capacity, low resistance, and excellent long-term durability with high yield.

  An embodiment of the present invention will be described with reference to FIG.

  FIG. 1 is a diagram showing an electric double layer capacitor electrode manufacturing apparatus 1 (hereinafter simply referred to as manufacturing apparatus 1) according to an embodiment of the present invention. The manufacturing apparatus 1 includes a gravure roll 4, an ink pan 5, a doctor blade 6, a guide roll 7a to a guide roll 7e, a pair of nip rolls 8a and 8b, a dryer 9, a first unwinding roll 10, a second unwinding roll 11, and A winding roll 12 is provided.

  In the manufacturing apparatus 1, the current collector 2 unwound from the first unwinding roll 10 is guided to the gravure coater 13 described later by the guide roll 7a. The current collector 2 exiting the gravure coater 13 is guided to the nip roll 8a and the nip roll 8b by the guide roll 7d. Further, the carbon sheet 14 unwound from the second unwinding roll 11 is bonded to the current collector 2 by a pair of nip rolls 8a and 8b.

  Further, in the manufacturing apparatus 1, the gravure coater 13 for applying the conductive adhesive 3 to the current collector 2 is a gravure having a diagonal cell pattern on the peripheral surface of the ink pan 5 containing the conductive adhesive 3. The roll 4 is impregnated. While the gravure roll 4 rotates in the direction opposite to the traveling direction of the current collector 2 serving as a coating substrate, the conductive adhesive excessively attached to the peripheral surface of the gravure roll 4 is removed by the doctor blade 6. The

  Thereafter, the gravure roll 4 comes into contact (close contact) with the current collector 2 supported by the two guide rolls 7 b and 7 c, thereby transferring the conductive adhesive 3 to the current collector 2. At this time, the gravure roll 4 is not provided with a backup roll, and a hard aluminum foil is used as the current collector 2.

  The structure in which the gravure roll 4 is not provided with a backup roll is generally called a kiss coating method, and is characterized in that a coating can be printed on the substrate with an extremely low printing pressure, that is, the conductive adhesive 3 can be applied. After the step of applying the conductive adhesive 3 to the current collector 2 using the kiss coating method in the gravure coater 13, the process proceeds to the step of continuously bonding the carbon sheet 14. Note that the coating speed of the gravure coater 13 is equal to the traveling speed of the current collector 2.

  In the bonding step, the manufacturing apparatus 1 is provided with a pair of nip rolls 8a and 8b, and it is desirable to manufacture the bonded electrode 15 by bonding the current collector 2 and the carbon sheet 14 while rolling between the rolls. . As a result, the bubbles inside the conductive adhesive 3 and the bubbles between the conductive adhesive 3 and the carbon sheet 14 are expelled, and the conductive adhesive 3 and the current collector 2, as well as the conductive adhesive 3 and the carbon. The adhesion of the sheet 14 can be improved.

  Furthermore, the tension of the carbon sheet 14 between the second unwinding roll 11 and the nip rolls 8a and 8b can be relaxed. For this reason, even if it is the carbon sheet 14 with small tensile strength, it can bond stably, without breaking the carbon sheet 14. FIG.

  Further, since the carbon sheet 14 is a porous material, the surface of the carbon sheet 14 can be impregnated with the conductive adhesive 3. There is an effect of promoting the impregnation of the conductive adhesive 3 into the carbon sheet 14 by the nip rolls 8a and 8b provided in the bonding portion.

  The pair of nip rolls 8a and 8b is not essential. For example, depending on the properties of the base material such as air permeability, the current collector 2 and the carbon sheet 14 can be satisfactorily bonded without the pair of nip rolls 8a and 8b.

  After the current collector 2 and the carbon sheet 14 are bonded together, the bonded electrode 15 is dried by the dryer 9. By selecting the drying temperature in the range of 50 ° C. to 200 ° C., it is possible to perform the drying well. A more preferred drying temperature range is from 80 ° C to 180 ° C.

  In addition, when bonding a carbon sheet on both surfaces of a hard aluminum foil, it can respond by performing the process which concerns on this Embodiment on both surfaces one side.

  The bonded electrode 15 dried by the dryer 9 is guided to the take-up roll 12 by the guide roll 7e and taken up.

  If a cell pattern of the gravure roll 4 is a quadrangular pyramid plate or a trapezoidal (lattice type) plate that is excellent in coating with a thin film, bubbles and aggregates present in the conductive adhesive 3 are used as a base point and Uncoated parts such as cracks and chips are likely to occur. For this reason, the possibility of causing poor coating of the conductive adhesive 3 is increased.

  On the other hand, when the conductive adhesive 3 is applied with a gravure roll 4 having a hatched cell pattern on its peripheral surface as shown in FIG. Therefore, the carbon sheet 14 can be bonded with a good yield. This is because the conductive adhesive 3 filled in the grooves formed along the oblique direction with respect to the rotation axis X is rotated on the peripheral surface of the gravure roll 4 when viewed from the direction perpendicular to the rotation axis X. On the peripheral surface of the gravure roll 4, the fluid constantly flows in the groove, and the fluid is transferred to the current collector 2. At this time, bubbles and aggregates in the conductive adhesive 3 flow through the groove and slide out along the groove. Therefore, the conductive adhesive is formed on the contact surface between the current collector 2 and the gravure roll 4. Only 3 remains. Therefore, since the conductive adhesive can be applied efficiently, transfer efficiency is improved. As a result, it is possible to prevent defective coating of the conductive adhesive 3 and to improve the yield.

  In the manufacturing apparatus 1, the groove may be carved in a spiral shape.

  Moreover, in the manufacturing apparatus 1, the cross section of the groove may be a triangle.

  Furthermore, in the manufacturing apparatus 1, the angle formed by the rotation axis X and the oblique direction may be 45 degrees.

  With these configurations, the conductive adhesive can be efficiently applied, so that transfer efficiency is improved. As a result, it is possible to prevent poor coating of the conductive adhesive and to improve the yield.

  As the oblique line version of the gravure roll 4 used in the present embodiment, a groove having a triangular cross section as shown in FIG. 3 spirally carved at an angle θ of 45 ° with respect to the rotation axis X of the roll is preferably used. Although it can be used, the angle of the groove is not limited to 45 °. The number of grooves can suitably be 100 to 250 lines per inch, more preferably 150 to 200 lines. Moreover, the depth of a groove | channel can use 10 to 80 micrometers suitably, More preferably, it is 30 to 50 micrometers.

  Further, in the present embodiment, the gravure roll 4 is rotated in the direction opposite to the traveling direction of the current collector 2, that is, rotated counterclockwise in FIG. The adhesive 3 was applied to the current collector 2 made of aluminum foil, and the bonded electrode 15 bonded to the carbon sheet 14 could be mass-produced. By rotating the gravure roll 4 in the direction opposite to the traveling direction of the current collector 2, a liquid pool 16 called a transfer bead is formed between the current collector 2 and the gravure roll 4 as shown in FIG. In addition, since the liquid reservoir 16 continuously supplies the conductive adhesive 3 to the current collector 2, it is possible to prevent a defect that an uncoated portion where the conductive adhesive 3 is not applied is generated on the coated surface.

  Conversely, when the conductive adhesive 3 is applied by rotating the gravure roll 4 in the forward direction, that is, clockwise in FIG. 4, since the liquid reservoir 16 is not formed, the conductive adhesive is applied to the current collector 2. 3 may cause a defect that leaves an uncoated part that is not coated.

  As the current collector 2, a metal foil such as aluminum, copper, titanium, tantalum, nickel, and stainless steel can be used. Among these, an aluminum foil that is inexpensive, has good electrical conductivity, and has excellent electrochemical corrosion resistance is preferably used.

  When an aluminum foil having a purity of 99.9% or more is used as the current collector 2, the surface is preferably hardly deteriorated, but if it is 99.8% or more, it can be suitably used. The thickness of the aluminum foil can be used between 6 μm and 100 μm, preferably between 10 μm and 50 μm.

  Further, in the present embodiment, as the aluminum foil used for the current collector 2, in addition to the hard aluminum foil having a smooth surface, a hard aluminum foil subjected to roughening treatment such as chemical etching, electrolytic etching, and sandblasting is used. May be used. It is preferable that the surface of the aluminum foil is roughened because the adhesion with the conductive adhesive 3 is increased by the anchor effect and the contact resistance is decreased.

  Furthermore, in the present embodiment, by using a hard aluminum foil that does not cause wrinkles or stretch, it is possible to effectively reduce the loss due to coating failure that occurs when the conductive adhesive 3 is applied, and The adhesive strength between the conductive adhesive 3 and the current collector 2 that is a hard aluminum foil can be improved.

  The aluminum foil includes a hard foil that is rolled and hardened by work hardening after rolling, and a soft foil that is softened by annealing the hard foil. The aluminum foil used in the present embodiment is a hard foil that is not annealed, and uses an H18 material defined by JIS H 4160.

  Hard aluminum foil is hard, elastic and has a low back. For this reason, even if a large stress is applied, no wrinkles are formed, and there is no elongation and deformation. Due to this property, when a hard aluminum foil is used as the current collector 2, it is possible to prevent defects and accidents in which the bonded electrode 15 is deformed.

  Furthermore, the inventors have found that the hard aluminum foil is a current collector suitable for application of the conductive adhesive 3 by the kiss coating method used in the present embodiment. That is, since the elastic hard aluminum foil has a repulsive force against the stress, the kiss coat type gravure roll 4 without the backup roll adheres to the hard aluminum foil used as the current collector 2 with an appropriate pressure. I can do it. By this action, the adhesion between the gravure roll 4 and the hard aluminum foil used as the current collector 2 is strong and stable. Accordingly, even when coating is performed at a high speed of 10 m / min or more, it is possible to prevent a defect in which an uncoated portion where the conductive adhesive 3 is not coated on the hard aluminum foil used as the current collector 2 is generated in advance. I can do it.

  Furthermore, when using an aluminum foil whose surface is subjected to etching treatment as the current collector 2, it is better to use a material obtained by etching a hard foil than that obtained by etching a soft foil. Will become stronger.

  In the present embodiment, when using an aluminum foil that has been subjected to AC etching treatment, the depth of the etching treatment layer on the surface of the aluminum foil is suitably used in an average range of about 5 μm to about 10 μm. As shown in FIG. 5, innumerable fine holes called etching pits exist in the etching treatment layer 21 on both surfaces of the aluminum foil, and the remaining core layer not roughened between the two etching treatment layers 21. 22 remains.

  In the case of a soft foil, the sponge-like structure is softer and more fragile than a hard foil, so that the adhesive strength between the aluminum foil and the conductive adhesive is relatively small. In the present embodiment, the use of the etched hard aluminum foil increases the adhesive strength between the hard aluminum foil and the conductive adhesive. As a result, the electric double layer capacitor manufactured by the manufacturing apparatus 1 The long-term durability can be improved.

  Furthermore, it is preferable that the conductive adhesive 3 used in the present embodiment includes a conductive filler, a binder, and a dispersant. Here, it is desirable to use carbon particles such as graphite and carbon black as the conductive filler, and it is more desirable to use two or more of these in combination.

  As the binder used for the conductive adhesive 3, carboxymethyl cellulose sodium salt, polyvinyl alcohol, polyvinyl acetate, polyacrylic ester, ethylene vinyl acetate copolymer, ionomer resin, polybutyral, nitrocellulose, styrene butadiene Rubber, butadiene acrylonitrile rubber, isoprene rubber, neoprene rubber, acrylic resin, phenol resin, melamine resin, polyurethane resin, urea resin, polyimide resin, polyamideimide resin, water glass and the like are used.

  In addition, water is preferably used as the dispersant used in the conductive adhesive 3, but other solvents such as lower alcohols such as methanol, ethanol, isopropyl alcohol, and butanol, dimethylformamide, xylene, acetone, and the like. Can be used alone or in combination.

  What is necessary is just to change suitably the viscosity of the conductive adhesive 3 used in this Embodiment by desired thickness and the property of the base-material surface. Specifically, the pressure is desirably 10 mPa · s (millipascal second) to 1000 mPa · s, and more desirably 100 mPa · s to 500 mPa · s.

  In the present embodiment, the carbon sheet 14 used for bonding the electrode for the electric double layer capacitor is formed by forming a raw material composition including an active material, a conductive filler, and a binder, which is a carbon material such as activated carbon, into a sheet shape. Composed.

  The activated carbon is not particularly limited as long as it is used for electric double layer capacitor applications, and powdered or fibrous activated carbon can be used. As the activated carbon, for example, those obtained by performing steam activation, phosphoric acid activation, or alkali activation of carbides made of raw materials such as palm, wood, coal pitch, petroleum pitch, mesophase pitch, coke, and phenol resin are used. .

  The conductive filler is blended for the purpose of improving the conductivity of the carbon sheet, and is a conductive fine powder usually used in the technical field, such as carbon black such as acetylene black, furnace black, ketjen black, carbon nano One type or two or more types of fiber, graphite, and metal powder can be used. The compounding amount of the conductive filler may be a conventionally known amount, and is generally in the range of 1% by mass to 35% by mass. When the blending amount of the conductive filler is larger than the above range, the capacitance decreases and the carbon sheet using carbon black as the conductive filler tends to decrease the impregnation property of the electrolytic solution.

  The binder is used to bind the activated carbon and the conductive filler, and examples of the binder that can be suitably used in the present invention include polytetrafluoroethylene (PTFE), ethylene-tetrafluoroethylene copolymer. , Fluorocarbon resins such as chlorotrifluoroethylene polymer, vinylidene fluoride polymer, and tetrafluoroethylene-fluoroalkyl vinyl ether copolymer, but are not particularly limited thereto.

  The carbon sheet 14 used in the present embodiment can be manufactured by a method known in the technical field. For example, activated carbon, conductive filler, binder dispersed in water, alcohol, oil, etc. and added to a wet kneaded material are pre-molded into rods or sheets by extrusion or roll molding. It can be obtained by roll rolling to a thickness. Further, a material obtained by dispersing and kneading in a dry manner without adding a dispersion medium to the material can also be obtained by roll molding. These methods are selected depending on the desired composition, density, and thickness of the carbon sheet.

〔Example〕
First, the carbon sheet 14 and the conductive adhesive 3 in the present example are obtained by the steps shown below.

[Carbon sheet]
Activated carbon powder (specific surface area: 2000 m ² / g, average particle diameter: 8 μm): 75 parts by mass, acetylene black (primary particle average particle diameter: 35 nm): 15 parts by mass, PTFE powder: 10 parts by mass, Ethanol: 100 parts by mass were added and kneaded and roll-rolled to obtain a long carbon sheet 14 having a width of 150 mm and a thickness of 150 μm.

[Conductive adhesive]
Natural scaly graphite (average particle size: 4 μm): 10 parts by mass, acetylene black (average particle size: primary particle 35 nm): 10 parts by mass, polyvinyl alcohol: 3 parts by mass, carboxymethylcellulose: 3 parts by mass, purified water: The conductive adhesive 3 was obtained by mixing and stirring 74 parts by mass.

  The electric double layer capacitor electrodes obtained in Comparative Examples 1 to 4 and Examples 1 to 3 shown below are vacuum-dried at 160 ° C. for 24 hours to remove moisture remaining in the conductive adhesive. did. Then, the adhesion test of the bonded electrode between the aluminum foil and the carbon sheet was performed. Further, as a sample for performing an adhesion test between an aluminum foil and a conductive adhesive, in Comparative Examples 1 to 4 and Examples 1 to 3, a carbon sheet is pasted after the conductive adhesive is applied to the aluminum foil. In addition, a test sample was obtained by performing the same drying as described above.

[Comparative Example 1]
For a soft aluminum foil having a thickness of 4 μm and an AC etching treatment on both sides with an average etching depth of 5 μm, a gravure roll having a square pyramid cell pattern is opposite to the traveling direction of the aluminum foil without providing a backup roll. The conductive adhesive 3 was applied in a state where the adhesive was rotated. The gravure roll coating speed at this time was set to 2 m / min. Then, the electrode for electric double layer capacitors was obtained by bonding a carbon sheet and making it dry with the dryer set to 80 degreeC.

[Comparative Example 2]
A bonded electrode was obtained in the same manner as in Comparative Example 1 except that the cell pattern of the gravure roll was hatched.

[Comparative Example 3]
A bonded electrode was obtained in the same manner as in Comparative Example 2 except that the gravure coater coating speed was 5 m / min.

[Comparative Example 4]
A bonded electrode was obtained in the same manner as in Comparative Example 2 except that the gravure coater coating speed was 10 m / min.

[Example 1]
A gravure having an oblique etching cell pattern without using a backup roll with respect to the hard aluminum foil, using a hard aluminum foil with a thickness of 40 μm having an average etching depth of 5 μm and AC etching on both sides as a current collector 2 The conductive adhesive 3 was applied in a state where the roll 4 was rotated in the direction opposite to the traveling direction of the aluminum foil. The coating speed of the gravure roll 4 at this time was 2 m / min. Thereafter, the carbon sheet 14 was bonded and dried with a dryer 9 set to 80 ° C., thereby obtaining a bonded 15 as an electrode for an electric double layer capacitor.

[Example 2]
A bonded electrode was obtained in the same manner as in Example 1 except that the coating speed of the gravi coater 13 was 5 m / min.

Example 3
A bonded electrode was obtained in the same manner as in Example 1 except that the coating speed of the gravi coater 13 was set to 10 m / min.

  The following three evaluations were performed on the obtained test samples. The results are shown in Table 1.

[Applying state of conductive adhesive]
In Comparative Examples 1 to 4 and Examples 1 to 3, the coating state of the conductive adhesive on the aluminum foil was observed over 50 m, and evaluated according to the following criteria for failure mode.

  That is, on the coated surface of the conductive adhesive, it is good when there is no uncoated part, and when the small uncoated part 20 is generated as shown in FIG. 6, it is defective, and the large uncoated part is intermittent. When it occurred, it was evaluated that coating was impossible.

[Adhesion between aluminum foil and conductive adhesive]
Adhesion was evaluated by a tape peel test. In a sample in which a conductive adhesive is simply applied to an aluminum foil having a width of 10 mm and a length of 100 mm, an adhesive tape (“Scotch tape” manufactured by Sumitomo 3M Limited) (15 mm wide and 120 mm long) is applied to the surface of the conductive adhesive layer. (Registered Trademark)) was pressed with a finger sufficiently to remove air bubbles between the conductive adhesive and the pressure-sensitive adhesive tape, and then the pressure-sensitive adhesive tape was peeled off, and the adhesion was evaluated according to the following formula.
Adhesiveness (%) = weight of conductive adhesive layer after peeling / weight of conductive adhesive layer before peeling × 100
[Adhesive strength between aluminum foil and carbon sheet]
The adhesive strength was evaluated by a tape peeling test. In a sample of a bonded electrode 15 of an aluminum foil (current collector 2) having a width of 10 mm and a length of 100 mm and a carbon sheet 14, an adhesive tape having a width of 15 mm and a length of 120 mm (manufactured by Sumitomo 3M Limited) is applied to the surface of the carbon sheet 14. After pressing the “Scotch tape” (registered trademark) with your finger enough to remove air bubbles between the carbon sheet 14 and the adhesive tape, peel off the adhesive tape, observe the peeled state of the carbon sheet part, and bond The force was evaluated according to the following failure mode criteria.

  That is, for example, when the cured conductive adhesive 3 layer breaks at the arrow A in FIG. 7, cohesive failure, the boundary surface between the conductive adhesive 3 layer and the aluminum foil (arrow B in FIG. 7), or conductive When the boundary surface between the layer of the adhesive 3 and the carbon sheet 14 (arrow C in FIG. 7) breaks, the bond breaks, and when the carbon sheet 14 breaks at, for example, the arrow D in FIG. did.

  In the standard of such a failure mode, in addition to the base material failure that occurs without fail, the strength of the conductive adhesive itself is insufficient when cohesive failure occurs, and the properties of the bonded base material when adhesive failure occurs Is not appropriate, or the bonding process is inappropriate.

〔result〕
From the results of Table 1, it can be seen that the electric double layer capacitor electrodes of Examples 1 to 3 exhibit higher productivity and good adhesive strength than the electric double layer capacitor electrodes of Comparative Examples 1 to 4. Recognize. That is, if an electric double layer capacitor is formed using an electrode manufactured by the electric double layer capacitor electrode manufacturing apparatus of the present invention, the long-term durability can be improved at a lower manufacturing cost.

  The above-described embodiments or examples are merely to clarify the technical contents of the present invention, and should not be construed in a narrow sense as being limited to such specific examples. Various modifications can be made within the spirit and scope of the claims.

  The electric double layer capacitor electrode manufacturing apparatus of the present invention can mass-produce high capacity and low resistance electric double layer capacitor electrodes at a high speed with high yield. It can be suitably used for the production of an electric double layer capacitor electrode of an electric double layer capacitor used for a power source or the like.

It is a figure which shows the manufacturing apparatus of the electrode for electric double layer capacitors which concerns on embodiment of this invention. It is a figure which shows the diagonal line plate used as a cell pattern of the gravure roll which concerns on embodiment of this invention. It is a perspective view which shows the triangular groove | channel carved on the surrounding surface of the gravure roll of FIG. It is a figure which shows rotating a gravure roll in the reverse direction with respect to the running direction of an electrical power collector. An infinite number of very fine holes called etching pits exist in the etching treatment layers on both sides of the aluminum foil, indicating that unroughened aluminum remains as a residual core layer between the two etching treatment layers. It is sectional drawing of aluminum foil. It is a figure which shows that an uncoated part arises when a conductive adhesive is applied to a collector. It is sectional drawing of the bonding electrode which performs a bonding electrode tape peeling test.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Manufacturing apparatus 2 Current collector 3 Conductive adhesive 4 Gravure roll 5 Ink pan 6 Doctor blade 7a-7e Guide roll 8a, 8b Nip roll 9 Dryer 10 1st unwinding roll 11 2nd unwinding roll 12 Rewinding roll 13 Gravure coater 14 Carbon sheet 15 Bonded electrode 20 Uncoated part 21 Etching layer 22 Remaining core layer AD Arrow X Rotating axis θ Angle

Claims (3)

It has a gravure roll that coats the current collector with conductive adhesive by kiss coat method,
In an apparatus for producing an electrode for an electric double layer capacitor, wherein a carbon sheet containing an active material that is a carbon material, a conductive filler that imparts conductivity, and a binder is bonded to the current collector via the conductive adhesive,
Manufacturing of an electrode for an electric double layer capacitor, wherein a groove is formed on a peripheral surface of the gravure roll along an oblique direction with respect to the rotation axis when viewed from a direction perpendicular to the rotation axis. apparatus.   The said current collector is a hard aluminum foil which does not give annealing, The manufacturing apparatus of the electrode for electric double layer capacitors of Claim 1 characterized by the above-mentioned.   The apparatus for manufacturing an electrode for an electric double layer capacitor according to claim 1, wherein the gravure roll rotates in a direction opposite to a traveling direction of the current collector.