JP2017098128A - Method for manufacturing membrane-electrode assembly - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress the deposition of an electrolyte membrane to a release layer when peeling a mold release film.SOLUTION: Peeling a first mold release film 24, a first catalyst ink 22 is divided into a transfer portion 22a and a removed portion 22b. The transfer portion 22a is a catalyst layer transferred to an electrolyte membrane 12. The removed portion 22b is, of the first catalyst ink 22, a portion sticking to a release layer 29, which is recovered together with the release layer 29 and the first mold release film 24.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a method for producing a membrane electrode assembly.

  As a manufacturing process of a membrane electrode assembly, there is a method of forming a catalyst layer on an electrolyte membrane by using a laminate in which a transfer film, a release layer, and a catalyst ink are laminated in this order and transferring the catalyst ink to the electrolyte membrane. Known (Patent Document 1).

JP, 2014-060167, A

  In the case of the above prior art, a part of the release layer may adhere to the catalyst ink when the transfer film is peeled off after the catalyst ink is transferred to the electrolyte membrane. The attached release layer remains in the membrane electrode assembly and reduces the power generation performance of the fuel cell. This invention makes it a solution subject to suppress adhesion to a mold release layer to an electrolyte membrane, when peeling a transfer film based on the said prior art.

  SUMMARY An advantage of some aspects of the invention is to solve the above-described problems, and the invention can be implemented as the following forms.

  According to the present invention, a method for producing a membrane electrode assembly is provided. The manufacturing method includes: a first step of transferring the catalyst layer to the electrolyte membrane by pressing the catalyst ink against the electrolyte membrane while heating the catalyst ink sandwiching the release layer together with the release film to form a laminate. And a second step of peeling the release film from the laminate that has undergone the first step; and the first step is performed at a temperature lower than the glass transition temperature of the release layer. According to this aspect, since glass transition does not occur in the release layer even after the first step, high adhesion between the release layer and the catalyst ink is maintained. As a result, after passing through the second step, the catalyst ink is divided into a part that adheres to the electrolyte membrane and a part that adheres to the release layer, while the release layer is entirely attached to the release film. For this reason, adhesion to the release layer to the electrolyte membrane can be suppressed.

Schematic of MEA manufacturing equipment. The flowchart which shows the process which manufactures a membrane electrode assembly. The figure which shows a mode that a 1st catalyst ink is transcribe | transferred to an electrolyte membrane. The figure which shows a mode that a release film is peeled typically. The figure which shows a mode that a release film is peeled (comparative example). The figure which shows the membrane electrode assembly manufactured in Embodiment 2. FIG.

  Embodiment 1 will be described. FIG. 1 is a schematic view of an MEA manufacturing facility 1 that continuously manufactures a membrane electrode assembly 90. The membrane electrode assembly is also called MEA. MEA is an acronym for Membrane Electrode Assembly.

  The MEA manufacturing facility 1 includes an electrolyte membrane roll 10, a first catalyst ink roll 20, a second catalyst ink roll 30, a slip sheet roll 40, an MEA roll 50, first rolls 62 and 64, Second rolls 82 and 84 and peeling rolls 72, 74 and 76 are provided.

  The electrolyte membrane roll 10 is a roll in which an electrolyte membrane 12 disposed on a support base material 14 is wound around a core tube. The electrolyte membrane 12 is an ion exchange membrane having good conductivity in a wet state. The electrolyte membrane 12 is made of a fluorine resin material such as Nafion (registered trademark). The support base material 14 is a reinforcing material for conveying the electrolyte membrane 12. The support substrate 14 is made of a fluororesin such as polyethylene terephthalate (PET), polyethylene naphthalate (PEN), or ETFE.

  The first catalyst ink roll 20 is formed by sandwiching a release layer 29 (see FIGS. 3 and 4) between the first release film 24 (see FIGS. 3 and 4) and the first catalyst ink 22. The laminated body is a roll wound around the core tube. The first catalyst ink 22 is composed of a catalyst in which platinum is supported on carbon black and a fluorine resin material such as Nafion.

  In the second catalyst ink roll 30, a laminate in which a release layer 29 is laminated on a second release film 34 and a second catalyst ink 32 is laminated on the release layer 29 is wound around a core tube. It is a roll.

  The slip sheet roll 40 is a roll in which the slip sheet 44 is wound around the core tube. The interleaf paper 44 is used to sandwich the membrane electrode assembly 90 manufactured in the MEA manufacturing facility 1 between the membrane electrode assemblies 90 when the membrane electrode assembly 90 is wound around the MEA roll 50.

  The first rolls 62 and 64 are a pair of pressing rolls having a cylindrical basic structure formed of a metal such as stainless steel and having the surface coated with silicon rubber or Teflon (registered trademark). The first rolls 62 and 64 are heated during operation of the MEA manufacturing facility 1.

  The first rolls 62 and 64 rotate synchronously while pressing each other with the electrolyte membrane 12 and the first catalyst ink 22 interposed therebetween. The temperature and rotation speed of the first rolls 62 and 64 are controlled by the first roll control unit 100 (see FIG. 1).

  The characteristics of the second rolls 82 and 84 are substantially the same as the characteristics of the first rolls 62 and 64 described above. The temperature and rotation speed of the second rolls 82 and 84 are controlled by the second roll control unit 200 (see FIG. 1).

  FIG. 2 is a flowchart showing a process for manufacturing the membrane electrode assembly 90. First, the catalyst layer as the anode is transferred to the electrolyte membrane 12 (S110). S110 is implemented in the site | part of the code | symbol 3 shown by FIG. S <b> 110 is a step of pressing the first catalyst ink 22 against the electrolyte membrane 12 while heating the first catalyst ink 22 included in the laminate fed from the first catalyst ink roll 20.

  FIG. 3 schematically shows the state of S110. As shown in FIG. 3, a release layer 29 is disposed between the first catalyst ink 22 and the first release film 24. The release layer 29 includes a release component and impurities.

  By S110, a glass transition occurs in the electrolyte contained in the first catalyst ink 22. The glass transition occurs because the first catalyst ink 22 is heated by the first rolls 62 and 64. That is, the first catalyst ink 22 reaches a temperature Tg2 described below in S110. The temperature Tg <b> 2 is a glass transition temperature of the electrolyte contained in the first catalyst ink 22.

  On the other hand, the release layer 29 does not reach the temperature Tg1 described below. The temperature Tg1 is the glass transition temperature of the release layer 29. The temperature Tg1 is a temperature equal to or higher than the temperature Tg2, and is higher than the heating temperature by the first rolls 62 and 64. That is, S110 is performed under conditions where the temperature of the first catalyst ink 22 and the release layer 29 is not less than the temperature Tg2 and less than the temperature Tg1. In addition, temperature Tg1 in this embodiment is 150-250 degreeC.

  Thereafter, the first release film 24 is peeled from the laminate pressed against the electrolyte membrane 12 in S110 (S120). S120 is implemented in the site | part of the code | symbol 4 shown by FIG.

  FIG. 4 schematically shows the state of S120. As shown in FIG. 4, by S120, the first catalyst ink 22 is divided into a transfer portion 22a and a removal portion 22b. The transfer portion 22a is a portion of the first catalyst ink 22 that is transferred to the electrolyte membrane 12 to form a catalyst layer. The removal portion 22 b is a portion of the first catalyst ink 22 that is attached to the release layer 29, and is a portion that is wound around the release roll 72 together with the release layer 29 and the first release film 24.

  As described above, the first catalyst ink 22 is divided because glass transition does not occur in the release layer 29 in S120 as in S110. That is, S120 is also performed when the temperature of the first catalyst ink 22 and the release layer 29 is equal to or higher than the temperature Tg2 and lower than the temperature Tg1.

  The reason why S120 is performed under the above temperature condition is that S120 is performed in a short time after the end of S110. In particular, since heating is not performed in S120, the temperature of the release layer 29 does not reach the temperature Tg1 in S120 unless the temperature reaches the temperature Tg1 in S110. That is, in the release layer 29, if the glass transition does not occur in S110, the glass transition does not occur in S120.

  As described above, if no glass transition occurs in the release layer 29 in S120, high adhesion between the release layer 29 and the first catalyst ink 22 is maintained. For this reason, as described above, the first catalyst ink 22 is divided by S120.

  Then, the support base material 14 is peeled (S140). Next, the catalyst layer as the cathode is transferred to the electrolyte membrane 12 (S150). That is, the second catalyst ink 32 is pressed against the electrolyte membrane 12 while heating the second catalyst ink 32 included in the laminate fed from the second catalyst ink roll 30. Subsequently, the second release film 34 is peeled off (S170).

  S150 and S170 have the same characteristics as S120 and S140. That is, the second catalyst ink 32 is divided, and the release layer (not shown) is all collected by adhering to the second release film 34.

  The joined body of the second catalyst ink 32, the electrolyte membrane 12, and the first catalyst ink 22 is a membrane electrode assembly 90. Finally, the membrane electrode assembly 90 and the interleaf paper 44 are overlapped and wound around the MEA roll 50 (S180).

  FIG. 5 schematically shows the state of S120 in the comparative example. In this comparative example, as described later, the condition of S110 is different from that of the embodiment. As shown in FIG. 5, the entire first catalyst ink 22 in the comparative example is transferred to the electrolyte membrane 12 without being divided.

  On the other hand, the release layer 29 is divided into a remaining portion 29a and a removed portion 29b. The remaining portion 29 a is a portion remaining in the first catalyst ink 22 in the release layer 29. The removal portion 29 b is a portion of the release layer 29 that is attached to the first release film 24, and is wound around the release roll 72 together with the first release film 24.

  In S110 of the comparative example, the heating temperature by the first rolls 62 and 64 is higher than the heating temperature in the embodiment. As a result, in S110, the temperature of the release layer 29 reaches the temperature Tg1. When the release layer 29 reaches the temperature Tg1, a glass transition occurs. For this reason, the fluidity | liquidity of the mold release layer 29 increases, and the mold release layer 29 is divided | segmented by S120.

  At least a part of the remaining portion 29a remains in the membrane electrode assembly 90 obtained by S180. That is, the release component and impurities of the release layer 29 remain in the membrane electrode assembly 90. The remaining release components and impurities reduce the gas diffusibility and proton conductivity of the first catalyst ink 22 and, consequently, the power generation performance.

  According to the above-described embodiment, the mold release component and the impurity hardly remain in the membrane electrode assembly 90, so that the above problem can be avoided.

Experiments related to the embodiment and the comparative example were conducted. This experiment is for examining the relationship between the remaining catalyst ink and the temperature Tg1. The remaining catalyst ink is calculated by the following equation.
Catalyst ink remaining (%)
= 100 × mass of removal site 22b / (mass of transfer site 22a + mass of removal site 22b)

  The experimental results are as follows. When the temperature Tg1 is 160 ° C., the remaining catalyst ink is 1%. When the temperature Tg1 is 200 ° C., the remaining catalyst ink is 0.4%. When the temperature Tg1 is 250 ° C., the remaining catalyst ink is 0% and the temperature Tg1 is 270 ° C. In this case, the remaining catalyst ink was 0%.

  The remaining catalyst ink is 0%, which corresponds to the comparative example. From the above results, it can be said that the temperature Tg1 is preferably about 160 ° C. or higher and lower than 250 ° C.

  A second embodiment will be described. FIG. 6 shows a membrane electrode assembly 90 manufactured in the second embodiment. In the second embodiment, a part of the membrane electrode assembly 90 (hereinafter referred to as the first portion 90a) is manufactured by the method of attaching the release layer 29 to the electrolyte membrane 12 as in the comparative example, and the remaining portion (hereinafter referred to as the following portion). The second portion 90b) is manufactured by a technique that does not allow the release layer 29 to adhere to the electrolyte membrane 12 as in the first embodiment.

  The first portion 90a is disposed on the air outlet side. The second portion 90b is disposed on the air inlet side. The air outlet side is the outlet side in the flow of air as the cathode gas in the state assembled as a fuel cell stack. The same applies to the entrance side.

  The effect of disposing the first portion 90a on the air outlet side is as follows. Since the first catalyst ink 22 is not divided in the first portion 90a, the surface of the first catalyst ink 22 becomes smooth. For this reason, flooding is suppressed by improving drainage, and power generation performance is improved. The remaining portion 29a is removed by water generated by power generation.

  The effect of disposing the second portion 90b on the air inlet side is as follows. In the second portion 90b, the transfer portion 22a as the catalyst ink is formed by dividing the first catalyst ink 22, so that irregularities are formed on the surface of the catalyst ink. The water retention is improved by the unevenness, so that drying of the electrolyte membrane 12 is suppressed. As a result, the power generation performance is improved.

  The present invention is not limited to the embodiments, examples, and modifications of the present specification, and can be implemented with various configurations without departing from the spirit of the present invention. For example, the technical features in the embodiments, examples, and modifications corresponding to the technical features in the embodiments described in the summary section of the invention are to solve some or all of the above-described problems, or In order to achieve part or all of the effects described above, replacement or combination can be performed as appropriate. If the technical feature is not described as essential in this specification, it can be deleted as appropriate. For example, the following are exemplified.

  S110 (pressing while heating) may be carried out under a temperature lower than Tg2. That is, S110 may be executed under the condition that glass transition does not occur in the electrolyte contained in the first catalyst ink. Even if the glass transition does not occur in the electrolyte contained in the first catalyst ink, if the glass transition does not occur in the release layer, the first catalyst ink is divided as in the embodiment. The same applies to the second catalyst ink.

DESCRIPTION OF SYMBOLS 1 ... MEA manufacturing equipment 10 ... Electrolyte membrane roll 12 ... Electrolyte membrane 14 ... Support base material 20 ... 1st catalyst ink roll 22 ... 1st catalyst ink 22a ... Transfer site 22b ... Removal site 24 ... 1st release film DESCRIPTION OF SYMBOLS 29 ... Release layer 29a ... Residual site | part 29b ... Removal site | part 30 ... 2nd catalyst ink roll 32 ... 2nd catalyst ink 34 ... 2nd release film 40 ... Interleaf paper roll 44 ... Interleaf paper 50 ... MEA roll 62 ... 1st roll 72 ... Peeling roll 82 ... 2nd roll 90 ... Membrane electrode assembly 90a ... 1st site | part 90b ... 2nd site | part 100 ... 1st roll control part 200 ... 2nd roll control part

Claims (1)

A first step of transferring the catalyst layer to the electrolyte membrane by pressing the catalyst ink against the electrolyte membrane while heating the catalyst ink sandwiching the release layer with the release film to form a laminate; and
Including a second step of peeling the release film from the laminate through the first step,
The manufacturing method of the membrane electrode assembly which implements the said 1st process at the temperature below the glass transition temperature of the said mold release layer.

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