JP2005322588A - Manufacturing device and method of electrode for fuel cell - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To enable to prevent electrode material powder on an electrolyte film from reverse flight in reversed polarity, to surely manufacture an electrode for a fuel cell as fine as is designed, and to form an electrode with a two-dimensional thickness distribution, in manufacturing one by transferring the electrode material powder on the electrolyte film with the use of electrostatic force. <P>SOLUTION: A developing roller 3 with the statically charged electrode material powder 2 is placed at a position away from an electrolyte film and a transfer roller 12, and the transfer roller 12 is coated or otherwise with resin 12a having a high resistance value to turn it into a high-resistance member. Further, cam rollers 7a, 7b rotating in interlocking with the transfer roller 12 are arranged between the developing roller 3 and the transfer roller 12 to change field intensity by changing intervals of the two rollers. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  TECHNICAL FIELD The present invention relates to an electrode manufacturing apparatus and method for use in a polymer electrolyte fuel cell, and more particularly to an electrode manufacturing apparatus and method by a so-called dry method in which an electrode material powder is allowed to fly to an electrolyte membrane using electrostatic force. .

  A polymer electrolyte fuel cell is known as one of the fuel cells, and a membrane electrode assembly (MEA) 50 having a configuration shown in FIG. 10 is a main component. The membrane electrode assembly 50 has a fuel electrode side electrode 52a and a diffusion layer 53a laminated on one side of an electrolyte membrane 51 that is an ion exchange membrane, and an air electrode side electrode 52b and a diffusion layer 53b laminated on the other side. The structure is such that one fuel cell called a single cell is formed by sandwiching the diffusion layers 53a, 53b side with a separator having a gas flow path.

  Usually, what is called a Nafion (registered trademark) film is used as the electrolyte film 51. The electrodes 52a and 52b are formed by preparing a mixed solution (catalyst ink) of a carbon carrier carrying a catalyst component such as platinum and an electrolyte solution which is an electrically conductive material, and screen-printing it on the electrolyte membrane 51. After forming the electrode material by applying the method and drying (wet method), and preparing the electrode material completely dry, or drying and removing the solvent from the catalyst ink, and charging the powdered electrode material Then, a method (dry method) is performed in which it is attached to a conveying roller or the like using electrostatic force, the attached electrode material powder is transferred to the electrolyte film 51, and is fixed by a fixing roller.

  As a dry method, in Patent Document 1 (Japanese Patent Laid-Open No. 2002-367616), as shown in FIG. 11, a charged electrode material powder 54 is electrostatically adhered onto a conveying roller 57, and this roller 57 and the back surface for transfer are used. A method and apparatus are described in which a voltage is applied between the electrodes 58 to electrostatically adhere the electrode material powder 54 to the electrolyte membrane 59 disposed between the roller 57 and the back electrode 58. As one embodiment, as shown in the figure, the back electrode 58 and the electrolyte membrane 59 are arranged separately from the transport roller 57, and the electrode material powder 54 adhered on the transport roller 57 is transferred to the transport roller 57 and the back electrode. Also shown is a control plate 60 that is made to fly toward the electrolyte membrane 59 by the electric field generated between the electrodes 58 and electrostatically adhere to it, and to control the transfer pattern of the electrode material powder along the conveying roller 57. . Reference numeral 61 denotes a fixing roller.

In Patent Document 2 (Japanese Patent Laid-Open No. 2003-163010) or Patent Document 3 (Japanese Patent Laid-Open No. 2003-163011), as in an electrostatic copying machine, the charged photosensitive drum is irradiated with light to eliminate static electricity. A method and an apparatus are described in which electrode material powder is adhered to a desired electrode image pattern by electrostatic force, and is transferred to an electrolyte film by pressure contact with a photosensitive drum and a pressure roller to form a desired electrode.
JP 2002-367616 A Japanese Patent Laid-Open No. 2003-163010 JP 2003-163011 A

  Production of fuel cell electrodes by using the electrostatic force described above to cause the electrode material powder on the transport roller to fly to the electrolyte film, or to transfer the electrode material powder electrostatically attached to the photosensitive drum in the required pattern to the electrolyte film. Compared with the wet method in which the catalyst ink is applied, the method has an advantage that problems such as damage to the electrolyte membrane due to the solvent and generation of cracks in the electrode due to swelling or shrinkage can be solved. The present inventors have been involved in the production of electrodes by a dry method, but in the process, an accurate electrode image pattern of electrode material powder is formed on the transport roller when trying to obtain a precise electrode image pattern. I experienced that there was no disturbance in the electrode image transferred to the electrolyte membrane. In order to know the cause, the difference between the dry transfer of the electrostatic copying machine and the dry method in the case of producing the fuel cell electrode was considered.

  Electrostatic copying machines and laser printers also perform dry copying (transfer) using electrostatic force. First, a copier force is created by applying a high voltage between the developing roller and the photoconductive drum to the charged toner having a copy image or a printed image formed as a charge distribution on the photoconductive drum and having a thin layer deposited on the developing roller. To electrostatically adhere to the charge distribution on the photosensitive drum. Next, a high voltage is applied between the photosensitive drum and the transfer roller, and the paper is conveyed between them to electrostatically transfer the toner on the photosensitive drum onto the paper. Thereafter, a transfer method is adopted in which the toner is fixed on the paper by thermocompression with a fixing roller, and an accurate copy image in accordance with the charge distribution on the photosensitive drum is obtained on the paper.

  Regardless of the principle that the image forming method in the electrostatic copying machine and the electrode manufacturing method in the fuel cell using the electrostatic force are the same in principle, in the electrode manufacturing, as described above. An accurate transfer image may not be obtained. The reason was understood through experiments as follows.

1. The toner of the electrostatic copying machine is an insulator of about 10 ¹⁴ Ω, whereas the electrode material powder is an electrode material and is a conductor of several Ω or less. In addition, a sheet used for an electrostatic copying machine has a high surface resistivity of ^{109 to 13} Ω (which varies depending on the environment due to hygroscopicity), but the electrolyte membrane exhibits a lower resistance value than that ( Note 1) When a voltage is applied to the electrolyte membrane, that is, when a potential difference occurs between the front and back surfaces of the membrane under a high electric field, it behaves as a conductor.

Note 1: When the surface resistivity of a 5 mil thick electrolyte membrane (Nafion membrane) is measured by connecting a Model 152P-CR test probe to a surface resistance meter Model 152 manufactured by TREK, 2 × 10 ⁵ when 10 V is applied. A low resistance value was shown. Even when the probe was changed to Model 152P-2P and the resistance was measured by the two-point method, it was 2 × 10 ⁵ Ω. Even when the same electrolyte membrane is placed on an aluminum plate and one terminal of Model 152P-2P is placed on the membrane and the other terminal is placed on the aluminum plate, the measurement shows 2 × 10 ⁵ Ω, and the thickness direction It was also shown to be a low resistance material.

  2. Due to the difference in the physical properties of the materials used, when manufacturing an electrode using electrostatic force, the following problems occur at the transfer portion, which hinders the formation of a precise transfer image. .

a. In an electrostatic copying machine, a photosensitive drum, a sheet, and a transfer roller are generally transferred while the transfer roller presses the sheet against the photosensitive drum in order to improve detail reproducibility. This is because the surface resistance of the paper is as high as about 10 ^{9 to 13} Ω, and the toner can be transferred from the photosensitive drum to the paper by Coulomb force by charging only the paper surface of the paper. On the other hand, in the production of fuel cell electrodes, the resistance of the electrolyte membrane corresponding to the paper is as low as 2 × 10 ⁵ Ω and exhibits a behavior as a conductor. Therefore, as described in Patent Document 2 or 3, pressure transfer With this configuration, current flows from the transfer roller through the electrolyte membrane and electrode material powder to the surface of the photosensitive drum. For this reason, an electric current flows into the electrode material powder on the photosensitive drum to change the charge amount, which is different from the charge distribution of the photosensitive drum. As a result, the electrode material powder moves and the shape of the developed electrode image changes, which may hinder accurate transfer of the electrode image.

  b. In the apparatus described in Patent Document 1, a high electric field is created between the back electrode 58 (corresponding to the transfer roller) 58 and the conveying roller 27, that is, between the transfer portions, by a transfer high-voltage power source, and the electrode material powder is applied to the electrolyte membrane. When electrostatically adhering, the electrode material powder loses its charge due to the current flowing through the high-voltage power supply, back electrode, and electrolyte membrane, and is charged to the opposite polarity, receives electrostatic force in the direction opposite to that during transfer, and reverses to the photosensitive drum. It may cause a transfer abnormality that flies (reflection phenomenon inside the electrode of a conductor sphere placed between high electric field electrodes). In some cases, it is not easy to obtain the required amount of adhesion. In the apparatus of Patent Document 1, it can be said that the control pattern 60 for controlling the transfer pattern is provided to take measures against the shape of the electrode pattern on the electrolyte membrane by reverse flight adhesion, but the apparatus is complicated and expensive. The electrode material powder containing an appropriate catalyst adheres to the control plate and the utilization efficiency is lowered, resulting in an increase in cost. Further, no measures are taken against the loss of the charge of the charged electrode material powder due to the current flowing from the other members constituting the apparatus to the electrolyte membrane 59.

  Furthermore, in any case, the electrode pattern transferred onto the electrolyte membrane is the electrode image itself on the developing roller, and has a partially different thickness, that is, a two-dimensional thickness distribution using the same apparatus. When it is required to form an electrode on an electrolyte membrane, it is not easy to quickly cope with it.

  The present invention has been made in view of the above circumstances. In an apparatus and method for manufacturing an electrode of a fuel cell by transferring an electrode material powder to an electrolyte membrane using an electrostatic force, the electrode pattern is refined. Even in such a case, the electrode image can be accurately formed on the developing portion, and the electrode material powder does not release the charge received once, and the formed electrode image is left as it is without causing a transfer abnormality. The electrode can be transferred onto the electrolyte membrane in a state by an electrostatic force, and if necessary, the thickness of the electrode transferred onto the electrolyte membrane can be reduced in two dimensions (both in the X direction and in the Y direction) by easy means. It is an object of the present invention to provide an electrode manufacturing apparatus and a manufacturing method for a fuel cell that can be made different from each other.

  A fuel cell electrode manufacturing apparatus according to the present invention includes a transfer unit having at least a developing unit that forms electrode material powder as a predetermined electrode image, and a transfer unit that transfers the electrode material powder from the developing unit onto the electrolyte membrane by electrostatic force; And a fixing unit for fixing the electrode material powder on the electrolyte membrane. In the transfer unit, the transfer unit and the electrolyte membrane are arranged separately from the developing unit, and the transfer unit is electrostatically attached to the electrolyte membrane. A fuel cell electrode manufacturing apparatus in which means for preventing the adhering electrode material powder from being charged to a reverse polarity is provided, wherein the developing unit has a transfer roller that charges and transfers the electrode material powder The transfer section has a transfer roller having a counter electrode facing the transfer electrode, and an electric field is generated between the two electrodes by applying a high voltage from a high-voltage power supply for transfer. Cage, further characterized in that is provided with mechanical means for varying the electric field strength between the two rollers by changing the distance between the developing roller and the transfer roller during the transfer.

  The method for producing an electrode of a fuel cell according to the present invention includes a step of forming electrode material powder as a predetermined electrode image on a developing roller, and an electrostatic force on the electrolyte membrane moving the electrode image on the developing roller on the transfer roller. A fuel cell electrode manufacturing method comprising at least a transferring step and a step of fixing an electrode material powder on an electrolyte membrane, wherein the distance between the developing roller and the transfer roller is changed between the two rollers. By changing the electric field strength, the amount of electrode material powder that adheres electrostatically to the electrolyte membrane is changed to form electrodes having portions with different thicknesses on the electrolyte membrane.

  In the present invention, since the transfer portion and the electrolyte film are arranged apart from the developing portion, current does not substantially flow from the transfer portion or the electrolyte film to the developing portion, and the electrode image of the developing portion changes. Can be prevented. In addition, since the transfer part is provided with means for preventing the electrode material powder electrostatically attached to the electrolyte membrane from being charged in the reverse polarity, the electrode material powder electrostatically attached to the transfer part is developed in the transfer section. It is possible to reliably prevent a reverse flight to cause a transfer abnormality. As a result, even if the electrode pattern is fine, an electrode image can be accurately formed on the developing portion, and can be electrostatically attached to the electrolyte membrane as it is. Since the electrode material powder on the electrolyte membrane is sent and fixed to the fixing portion while maintaining a fine electrode pattern, a highly accurate fuel cell electrode can be obtained.

  Furthermore, in the present invention, the interval between the developing roller having a transfer electrode that charges and transfers the electrode material powder constituting the developing portion and the transfer roller having the counter electrode facing the transfer electrode constituting the transfer portion is changed. Since the mechanical means for changing the electric field strength between the two rollers is provided, electrostatic transfer of the electrode material powder is performed while appropriately changing the interval between the two rollers via the mechanical means. Can change the amount of electrode material powder that adheres electrostatically to the electrolyte membrane, and use an electrode having a two-dimensional thickness distribution (that is, different in thickness in one or both of the X and Y directions) as the electrolyte membrane. Can be formed.

  There is no particular limitation on the mechanical means for changing the distance between the developing roller and the transfer roller, but since it is easy to configure, it is a rolling roller interposed between the developing roller and the transfer roller. Desirably, the material of the rolling roller may be an insulator and may be a conductor because the transfer roller is insulated, but it is preferable to use a high resistance material of about 10 MΩ to 100 GΩ. Thereby, it is possible to obtain the amount of change in the electric field strength between the two rollers caused only by the change in the distance between the developing roller and the transfer roller without hindering the formation of an accurate electrode pattern on the electrolyte membrane, An electrode having a desired thickness change can be formed on the electrolyte membrane. When the rolling roller is an insulator, it is easy to be charged and dust or the like is easily attached, and it is difficult to remove the charge. Therefore, a semiconductor or a resistor slightly higher than that is a preferable embodiment.

  The electrostatic force necessary for transferring the electrode material powder, that is, the Coulomb force Fc, is determined by the charge q of the electrode material powder and the electric field E between the developing roller and the transfer roller, and Fc = q · E. The electric field E between the two rollers is E = V / d from the transfer power supply voltage V and the roller interval (electrode interval) d. When the distance r from the center of the rolling roller to the outer edge is proportional to the roller distance d, the roller distance d is determined by the distance r from the center of the rolling roller to the outer edge, whereby the electric field E and Coulomb force Fc for transferring the electrode material powder is determined.

  Accordingly, if the transfer power supply voltage V is constant and the rolling roller is circular, electrodes having the same thickness can be formed. Further, the thickness of the roller becomes larger as the radius r of the rolling roller becomes larger, the electric field E between the rollers becomes smaller, the Coulomb force Fc becomes weaker, the flying amount of the electrode material powder decreases, and the electrode becomes thinner. . Conversely, as the radius r decreases, the roller spacing d decreases and the electrodes increase in thickness.

  Therefore, when two rolling rollers are arranged between the developing roller and the transfer roller on both sides in the width direction of the electrolyte membrane, the two rolling rollers are cam rollers (that is, the distance between the rotation center and the outer edge of the roller). If the cam contours of the two cam rollers have the same shape and are rotated in the same phase, the movement direction of the electrolyte membrane (longitudinal direction) Thus, an electrode having a thickness changed in proportion to the cam profile is formed (claim 3). Even if the cam contours of the two cam rollers have the same shape, if the rotation is out of phase, the roller interval (electrode interval) d changes not only in the longitudinal direction but also in the width direction. Further, an electrode having a changed thickness is formed also in the width direction. Further, even when the two cam rollers have cam contours of different shapes, it is possible to form an electrode whose thickness varies in the longitudinal direction and the width direction. When the shape of the cam roller is an ellipse, it is desirable that the ratio of the major axis to the minor axis is not so large (for example, about 1.25 times) so as to suppress vibration of the apparatus during transfer.

  The rolling roller may be a circular roller instead of a cam roller. However, in that case, it is necessary that the two circular rollers disposed on both sides in the width direction of the electrolyte membrane have different diameters. In this case, since a change in the roller interval (electrode interval) d is formed in the width direction of the electrolyte membrane according to the difference in diameter between the two circular rollers, an electrode whose thickness changes in the width direction can be obtained.

  The rolling roller is provided between the developing roller and the transfer roller so that the position of the developing roller relative to the transfer roller can be changed while rolling independently of the developing roller. Further, when the rolling roller is a cam roller, the two cam rollers are mounted so as to be able to rotate in synchronism, that is, while always maintaining the initially set phase. Preferably, the two rolling rollers are set so as to rotate in conjunction with the transfer roller, and are attached to the developing roller so that they can roll in an unconstrained state. Specifically, there is an aspect in which a case (for example, a case for accommodating the electrode material powder and the developing roller) that accommodates the developing roller and a rolling roller are brought into contact with each other.

  In the present invention, the means for preventing the electrode material powder electrostatically attached to the electrolyte membrane, which is formed on the transfer portion, from being charged with a reverse polarity is basically applied to the electrode material powder that is a conductor. Any means may be used as long as it is a means for making it difficult for the current to flow. For example, a means for producing a region that faces the electrolyte membrane of the transfer portion with a material having a high resistance value, or an electrode of the transfer portion and a high-voltage power supply for transfer are connected via a resistor having a high resistance value. Means etc. are mentioned. In this case, if the high resistance value is in the range of 10 MΩ to 100 GΩ, the intended purpose can be effectively achieved.

  Preferably, the member other than the member constituting the transfer portion, which is in contact with the electrolyte membrane during the electrode manufacturing process, is made of a material having a high resistance value at least in a region that is in contact with the electrolyte membrane. Or connected to the earth, and the electrode material powder that is electrostatically attached to the electrolyte membrane from these members can be prevented from being charged or reduced as much as possible, thereby preventing the electrode material powder from being charged to the opposite polarity. To do. By doing so, it is possible to more reliably prevent a transfer abnormality that reversely flies to the developing portion. Examples of the member that comes into contact with the electrolyte membrane during the manufacturing process of the electrode include a fixing unit, a roll unwinding of the electrolyte membrane, a winding unit, a conveyance unit, and a storage unit.

  The present invention can also be applied to so-called batch-type electrode manufacturing in which electrode material powder is fixed to an electrolyte membrane that has been cut in advance of a predetermined size. It can also be applied to continuous electrode production in which the electrode material powder is continuously fixed. In the latter case, the number of transfer units described above may be one for the entire apparatus, but two or more transfer units may be arranged in tandem in the transport direction of the electrolyte membrane. Thereby, an electrode having an arbitrary three-dimensional structure can be produced. Further, two or more transfer units are arranged in tandem in the transport direction on one side of the electrolyte membrane, and two or more transfer units are arranged in tandem in the transport direction on the other side of the electrolyte membrane. Good. By arranging the transfer unit in this way, the air electrode and the fuel electrode in the membrane electrode assembly can be formed at the same time with an optimum structure.

  As described above, in the present invention, the mechanical means for changing the electric field strength between the two rollers by changing the distance between the developing roller and the transfer roller during the transfer is provided, and the developing roller is used as the mechanical means. When a rolling roller is arranged in the transfer roller, if a rolling roller having a large diameter change amount is used, the vibration of the apparatus may become unacceptable during the transfer operation. In order to avoid this and obtain an electrode having a required two-dimensional thickness distribution, it is extremely effective to arrange two or more transfer units in tandem. That is, for example, even when an elliptical cam roller having a very small ratio of the major axis to the minor axis is used as a rolling roller, the electrode having the required two-dimensional thickness distribution can be ensured by repeating it two or three steps. It can be manufactured.

  According to the present invention, when producing an electrode of a fuel cell by transferring an electrode material powder to an electrolyte membrane using an electrostatic force, even if the electrode pattern is fine, the electrode image is accurately applied to the developing portion. Can be formed. Moreover, the electrode material powder can transfer the formed electrode image onto the electrolyte membrane as it is without causing any abnormal transfer so as not to release the charge received once by the electrode material powder. This makes it possible to reliably manufacture the fuel cell electrode as designed. Further, since the electric field strength between the two rollers is changed by changing the distance between the developing roller and the transfer roller by mechanical means, the thickness of the electrode transferred onto the electrolyte membrane with a simple configuration. Can be made different in a two-dimensional direction (one or both of the X and Y directions).

  Hereinafter, the present invention will be described based on embodiments and examples with reference to the drawings. FIG. 1 is a schematic view showing an example of a fuel cell electrode manufacturing apparatus according to the present invention. In this apparatus A, an electrode material powder filling hopper 1 having an opening at the lower end is disposed so as to face a transfer roller 12 described later, and the electrode material powder 2 is filled therein. A developing roller 3 is accommodated in the lower part of the electrode material powder filling hopper 1 and grounded. The developing roller 3 has an electrode pattern recess 4 as shown in FIG. 3, and a transfer electrode 5 is attached to the bottom thereof. One electrode of the transfer high-voltage power supply 13 is connected to the transfer electrode 5, the output of the transfer high-voltage power supply 13 is set to 0V, and the transfer electrode 5 is set to 0V. A thin layer forming blade 6 is attached in the electrode material powder filling hopper 1 to help the electrode material powder 2 to be filled in the electrode pattern recess 4 of the developing roller 3.

  A web-like electrolyte film 8 is used as the electrolyte film, and the electrolyte film 8 fed from the electrolyte film unwinding roller 9 passes through the transport roller 10, the transfer roller 12, the transport roller 11, and the fixing rollers 14 and 14. The electrolyte membrane winding roller 15 is wound and stored. The other electrode of the transfer high-voltage power supply 13 is connected to the counter electrode of the transfer roller 12, and in this example, the transfer high-voltage power supply 13 outputs -4 kV.

In order to improve the sliding of the transfer roller 12, an aluminum pipe is coated with a resin 12a having a volume resistivity of 1 × 10 ¹² Ωcm and a thickness of 1 mm. Furthermore, the electrolyte membrane unwinding roller 9, the electrolyte membrane winding roller 15, the transport rollers 10, 11, and the fixing rollers 14, 14 are all resins 9a, 15a, 10a having a volume resistivity of 1 × 10 ¹¹ Ωcm and a thickness of 2 mm or more. , 11a, 14a, and 15a, respectively, and are grounded.

  Two cam rollers 7 a and 7 b having the same shape are interposed between the developing roller 3 and the transfer roller 12. This cam roller corresponds to the “rolling roller” in the present invention. As shown well in FIGS. 2 and 3, in this example, the cam rollers 7a and 7b are elliptical, and the ratio of the major axis to the minor axis is approximately 1.1 to 1.2. The two cam rollers 7a and 7b are attached to the support shafts 7A and 7B with the same phase.

  The two cam rollers 7 a and 7 b are in contact with the transfer roller 12 at positions on both sides of the transfer roller 12 outside the area where the electrolyte film 8 is conveyed, and are rotated in conjunction with the transfer roller 12. . The two cam rollers 7a and 7b are simultaneously in contact with the lower end of the electrode material powder filling hopper 1, and when the two cam rollers 7a and 7b rotate in conjunction with the rotation of the transfer roller 12, the electrode material is moved along the cam locus. The powder filling hopper 1, that is, the developing roller 3 moves up and down (in FIG. 2 and FIG. 3, the electrode material powder filling hopper 1 is omitted for easy understanding of the operation).

  FIG. 2 shows a state in which the short diameter portions of the two cam rollers 7a and 7b are in contact with the transfer roller 12 and the electrode material powder filling hopper 1 (developing roller 3), and the developing roller 3 is at the lowest position. FIG. 3 shows a state in which the two cam rollers 7a and 7b are rotated by 90 ° so that the long diameter portion is in contact with the transfer roller 12 and the electrode material powder filling hopper 1 (developing roller 3). is there. The developing roller 3 smoothly moves up and down between the position in FIG. 2 and the position in FIG. 3 according to the rotation angle of the two cam rollers 7a and 7b, and the electric field strength between the two rollers also changes accordingly. .

  When manufacturing an electrode, the electrode material powder 2 is first put in the electrode material powder storage case 1. When the developing roller 3 rotates, the electrode material powder 2 in the electrode material powder storage case 1 is filled into the electrode pattern concave portion 4 on the developing roller 3 by the thin layer forming blade 6. As described above, at this time, the voltage of the transfer electrode 5 provided at the bottom of the electrode pattern recess 4 is 0V.

  When the developing roller 3 rotates and the electrode pattern concave portion 4 comes on the electrolyte film 8 as shown in FIG. 3, the transfer high-voltage power supply 13 outputs -4 kV, for example. As a result, a high voltage V is applied between the transfer electrode 5 on the developing roller 3 and the transfer roller 12 (opposite electrode thereof), and the distance between the two rollers (that is, the cam roller 7a). , 7b), a strong electric field E having a magnitude depending on the rotation angle is formed. At the same time, since the transfer high-voltage power supply 13 charges the electrode material powder 2, the electrode material powder 2 filled in the electrode pattern concave portion 4 flies by receiving the Coulomb force Fc depending on the electric field strength, and is statically applied to the electrolyte membrane 8. Electrodeposit.

  The electrolyte membrane 8 is conveyed from the electrolyte membrane unwinding roller 9 by the conveying rollers 10 and 11 at a required speed, and the transfer roller 12 also rotates in synchronization. As described above, the cam rollers 7a and 7b are rotated in conjunction with the transfer roller 12, and the cam rollers 7a and 7b are rotated along with the conveyance of the electrolyte film 8, and the electrode material is formed in accordance with the elliptical cam contour. The powder filling hopper 1 (developing roller 3) is moved up and down. As a result, the distance d between the developing roller 3 and the transfer roller 12 changes, and the electric field strength E also changes. Accordingly, since the Coulomb force Fc also changes, as a result, the electrode material powder 2 is transferred onto the electrolyte film 8 with a thickness proportional to the distance d between the developing roller 3 and the transfer roller 12.

  When the developing roller 3 further rotates and the electrode pattern concave portion 4 passes over the electrolyte membrane 8, the transfer high-voltage power supply 13 becomes 0V and the electric field disappears. The electrode material powder 2 adhered on the electrolyte membrane 8 is heat-pressed by the fixing roller 14 and fixed on the electrolyte membrane 8 to become an electrode. The produced fuel cell electrode is taken up by the take-up roller 15.

  In the above apparatus, the electrolyte membrane unwinding roller 9, the electrolyte membrane winding roller 15, the transport rollers 10, 11 and the fixing roller 14 are coated with a resin having a high resistance value and are grounded. For this reason, almost no current flows from these rollers into the electrode material powder 2 transferred onto the electrolyte film 8, and the transfer roller 12 has a high resistance and hardly flows current. Therefore, the developing roller 3 and the transfer roller 12 The electrode material powder 2 adhering to the electrolyte membrane 8 is reversely charged while passing between the strong electric fields between them, and does not fly backward to the developing roller 3, and the fuel cell electrode as designed with no image disturbance Can be reliably manufactured.

[Example 1]
A fuel cell electrode was produced using the above-described apparatus described with reference to FIGS. As the electrode material powder 2, a powder made of Pt carrier carbon powder having a particle diameter of 1 to 10 μm and an electrolyte resin was used. As the transfer roller 12, an aluminum pipe coated with a resin 12a having a volume resistivity of 1 × 10 ¹² Ωcm and a thickness of 1 mm was used. The electrolyte membrane unwinding roller 9, the electrolyte membrane winding roller 15, the transport rollers 10 and 11, and the fixing rollers 14 and 14 are all coated with a resin having a volume resistivity of 1 × 10 ¹¹ Ωcm and a thickness of 2 mm or more, and are grounded. .

  The output of the transfer high-voltage power supply 13 was set to 0 V, the voltage of the transfer electrode 5 was set to 0 V, and −4 kV was output to the counter electrode of the transfer roller 12 during transfer. The electrolyte membrane 8 was conveyed at a speed of 30 mm / sec by the conveying rollers 10 and 11. As the cam rollers 7a and 7b, elliptical cam rollers having a major axis of 4.3 mm and a minor axis of 3.7 mm were used.

When a part of the coated surface was cut out and the weight of the catalyst amount per unit area of the electrode formed on the electrolyte membrane 8 was measured, it was as shown in FIG. 4. The minor axis portion was 0.044 mg / cm ² , the major axis The portion was 0.036 mg / cm ² . It was found that the transfer amount of the electrode material powder in the longitudinal direction, that is, the electrode thickness changed. Moreover, the electrode image transferred onto the electrolyte membrane is the same as the electrode image electrostatically attached to the electrode pattern concave portion 4 of the developing roller 3 except for the change in thickness, and the electrode material powder was applied in reverse flight. No evidence was observed.

[Example 2]
In the apparatus shown in FIG. 1, as shown in FIG. 5, electrodes were formed in the same manner as in Example 1 except that the cam rollers 7a and 7b were replaced with a circular roller 7a1 having a diameter of 5 mm and a circular roller 7b1 having a diameter of 3 mm.

When the amount of catalyst per unit area of the electrode formed on the electrolyte membrane was measured by the same method as in Example 1, as shown in FIG. 6, the amount of adhesion in the width direction of the electrolyte membrane changed according to the roller spacing. and is an average of the roller spacing 3.7 mm 0.042 mg ^/ cm 2, and an average 0.038 mg / cm ² at 4.3 mm. Further, the electrode image transferred onto the electrolyte membrane 8 is the same as the electrode image electrostatically attached to the electrode pattern concave portion 4 of the developing roller 3 except for the change in thickness in the width direction, and the electrode material powder is reversed. No evidence of flying and adhering was observed.

[Example 3]
In the apparatus shown in FIG. 1, as shown in FIG. 7, electrodes were formed in the same manner as in Example 1 except that one cam roller 7a was changed to a circular roller 7a2 having a diameter of 3 mm.

  When the amount of catalyst per unit area of the electrode formed on the electrolyte membrane was measured by the same method as in Example 1, the thickness of the electrode adjacent to the circular roller 7a2 did not change, but the elliptical cam roller The electrode on the side close to 7b was gradually thinner in the longitudinal direction.

[Example 4]
Although not shown in the drawing, electrodes were prepared in the same manner as in Example 1 except that the cam rollers 7a and 7b were attached with a 90 ° phase shift in the apparatus shown in FIG. As a result, the thickness of the electrode changed from thick to thin on the right side, and changed from thin to thick on the left side, and an electrode having a constant intermediate thickness was formed at the center.

  FIG. 8 is a schematic view showing still another example of a fuel cell electrode manufacturing apparatus according to the present invention. In this apparatus A1, the part composed of the transfer roller 12, the transfer high-voltage power supply 13, the electrode material powder filling hopper 1 including the developing roller 3 and the like in the apparatus A shown in FIG. A plurality (three in the figure) of the electrolyte membrane 8 are arranged in tandem in the transport direction of the electrolyte membrane 8.

  In the apparatus of the present invention, if a cam roller 7a, 7b having an excessively large ratio between the major axis and the minor axis is used, vibration during rotation exceeds an allowable limit. The change in electrode thickness is naturally limited. However, as in the apparatus shown in FIG. 8, by arranging a plurality of transfer units 20 in tandem, one electrode can be formed by a plurality of times of transfer, so that the above-described inherent effects of the present invention are maintained. However, it is possible to reliably produce an electrode having a sudden thickness change.

  FIG. 9 is a schematic view showing still another example of a fuel cell electrode manufacturing apparatus according to the present invention. In this apparatus A2, a plurality of transfer units 20 are arranged in tandem (three in the figure) in the transport direction of the electrolyte membrane 8 on one surface side (for example, the fuel electrode side) of the electrolyte membrane, On the other side of the electrolyte membrane (for example, the air electrode side), a plurality (three in the illustrated example) are arranged in tandem in the transport direction of the electrolyte membrane 8 in a state where the direction is reversed.

  In this apparatus, an electrode image having a thickness change can be formed on both surfaces of the electrolyte membrane 8 in a series of steps while maintaining the above-described intrinsic effects of the present invention. In the illustrated example, the fixing roller 14a is arranged after the transfer on the fuel electrode side, and the fixing roller 14b is also arranged after the transfer on the air electrode side. However, the electrode material powder and the electrolyte film 8 are damaged by thermocompression bonding. In order to reduce this, it is possible to omit the fixing roller 14a on the preceding side, that is, after the transfer on the fuel electrode side. In addition, the transfer unit arranged on the fuel electrode side of the electrolyte membrane and the transfer unit arranged on the air electrode side are different in the shape of the rolling roller and the type of electrode material powder to be filled. It is also possible to create an optimum electrode for each air electrode side electrode.

  In the above description, the developing roller 3 having the electrode pattern concave portion 4 is used. However, in the present invention, the electrode pattern concave portion 4 is not essential, and an electrode image of a required pattern is formed on the developing roller 3. Can be omitted on the condition that is formed.

The schematic diagram which shows an example of the electrode manufacturing apparatus of the fuel cell by this invention. It is a figure which expands and shows the part of a rolling roller (cam roller), and has shown the state which has a developing roller in the lowest position. It is another figure which expands and shows the part of a rolling roller (cam roller), and has shown the state which has a developing roller in the highest rank. 3 is a graph showing changes in electrode thickness in Example 1. FIG. FIG. 6 is a diagram showing a main part of an apparatus used in Example 2. 6 is a graph showing changes in electrode thickness in Example 2. FIG. 6 is a diagram showing a main part of an apparatus used in Example 3. The schematic diagram which shows the further another example of the electrode manufacturing apparatus of the fuel cell by this invention. The schematic diagram which shows the further another example of the electrode manufacturing apparatus of the fuel cell by this invention. The schematic diagram for demonstrating the membrane electrode assembly used with a polymer electrolyte fuel cell. The schematic diagram which shows an example of the electrode manufacturing apparatus of the conventional fuel cell.

Explanation of symbols

  DESCRIPTION OF SYMBOLS A ... Fuel cell electrode manufacturing apparatus, 1 ... Electrode material powder filling hopper, 2 ... Electrode material powder, 3 ... Developing roller, 4 ... Electrode pattern recessed part, 5 ... Transfer electrode, 6 ... Thin layer formation blade, 7a, 7b ... cam rollers (rolling rollers), 7a1, 7b1 ... circular rollers (rolling rollers), 8 ... web-like electrolyte film, 9 ... electrolyte film unwinding roller, 10, 11 ... conveying roller, 12 ... transfer roller, 14 ... Fixing roller, 15 ... electrolyte film winding roller, 9a, 10a, 11a, 12a, 14a, 15a ... resin coating, 13 ... high voltage power supply for transfer

Claims (12)

Fixing the electrode material powder on the electrolyte membrane, and a transfer unit having at least a developing portion for forming the electrode material powder as a predetermined electrode image and a transfer portion for transferring the electrode material powder from the development portion onto the electrolyte membrane by electrostatic force A transfer unit, and the transfer unit and the electrolyte film are arranged separately from the developing unit, and the electrode material powder electrostatically attached to the electrolyte film is charged to a reverse polarity in the transfer unit. An apparatus for manufacturing an electrode of a fuel cell, which is provided with means for preventing
The developing unit has a developing roller having a transfer electrode for charging and transferring the electrode material powder, the transfer unit has a transfer roller having a counter electrode facing the transfer electrode, and a high-voltage power supply for transfer between the two electrodes In addition, a mechanical means for changing the electric field strength between the two rollers by changing the distance between the developing roller and the transfer roller during the transfer is generated by applying a high voltage to the electric field. An electrode manufacturing apparatus for a fuel cell, comprising:   2. The electrode manufacturing apparatus according to claim 1, wherein the mechanical means is a rolling roller interposed between the developing roller and the transfer roller.   The rolling rollers are two cam rollers arranged on both sides in the width direction of the electrolyte membrane, and the two cam rollers have the same cam profile and are rotated in the same phase. The electrode manufacturing apparatus according to claim 2.   The rolling rollers are two cam rollers arranged on both sides in the width direction of the electrolyte membrane, and the two cam rollers have the same cam contour and are rotated with a phase shift. The electrode manufacturing apparatus according to claim 2.   3. The electrode manufacturing apparatus according to claim 2, wherein the rolling rollers are two cam rollers disposed on both sides in the width direction of the electrolyte membrane, and the two cam rollers have cam profiles having different shapes.   3. The electrode manufacturing apparatus according to claim 2, wherein the rolling rollers are two circular rollers having different diameters arranged on both sides in the width direction of the electrolyte membrane.   The means for preventing the electrode material powder from being charged with a reverse polarity is a means for producing a region that faces the electrolyte membrane of the transfer portion with a material having a high resistance value. The electrode manufacturing apparatus of the fuel cell in any one of 1-6.   The means for preventing the electrode material powder from being charged with a reverse polarity is a means for connecting the electrode of the transfer portion and the high-voltage power supply for transfer via a resistor having a high resistance value. The electrode manufacturing apparatus of the fuel cell in any one of 1-6.   The members other than the members constituting the transfer portion, which are in contact with the electrolyte membrane in the manufacturing process of the electrodes, are made of a material having a high resistance value in the region that is in contact with the electrolyte membrane. The electrode material powder electrostatically attached to the electrolyte membrane is prevented from being charged to prevent the electrode material powder from being charged to a reverse polarity. The fuel cell electrode manufacturing apparatus according to claim 1.   The fuel cell electrode manufacturing apparatus according to claim 1, wherein two or more transfer units are arranged in tandem in the transport direction of the electrolyte membrane.   Two or more transfer units are arranged in tandem in the transport direction on one surface side of the electrolyte membrane, and two or more transfer units are arranged in tandem in the transport direction on the other surface side of the electrolyte membrane. The fuel cell electrode manufacturing apparatus according to claim 10.   The process of forming electrode material powder on the developing roller as a predetermined electrode image, the process of transferring the electrode image on the developing roller onto the electrolyte film moving on the transfer roller by electrostatic force, and fixing the electrode material powder on the electrolyte film And an electrode for electrostatically adhering to the electrolyte membrane by changing the electric field strength between the two rollers by changing the distance between the developing roller and the transfer roller. An electrode manufacturing method for a fuel cell, wherein an electrode having a portion having a different thickness is formed on an electrolyte membrane by changing a material powder amount.

Images