Process for producing membrane/electrode assembly for polymer electrolyte fuel cell

A process for producing a membrane/electrode assembly for polymer electrolyte fuel cells, comprising an anode and a cathode each having a catalyst layer and a gas diffusion layer;

• and a polymer electrolyte membrane disposed between the catalyst layer of the anode and the catalyst layer of the cathode, which comprises:
• applying a dispersion containing a fluorinated ion exchange resin and carbon nanofibers having a fiber diameter of from 1 to 1,000 nm and a fiber length of 5 μm to 1,000 μm, on a substrate, followed by drying to prepare a carbon layer;
• applying a coating fluid containing a catalyst and an ion exchange resin thereon, followed by drying to prepare the catalyst layer;
• heating and pressing the applied surface while the surface is adjacent to the electrolyte membrane so as to transfer the catalyst layer and the carbon layer on the surface of the above electrolyte membrane;
• and peeling the substrate;
• and disposing the gas diffusion layer so as to be adjacent to the carbon layer, thereby to prepare at least one of the above cathode and the above anode, wherein the carbon nanofibers and the fluorinated ion exchange resin are contained in a mass ratio of from 1:0.1 to 1:5 in the carbon layer.

A process for producing a membrane/electrode assembly for polymer electrolyte fuel cells, comprising an anode and a cathode each having a catalyst layer and a gas diffusion layer;

• and a polymer electrolyte membrane disposed between the catalyst layer of the anode and the catalyst layer of the cathode, which comprises:
• applying a dispersion containing a fluorinated ion exchange resin and carbon nanofibers having a fiber diameter of from 1 to 1,000 nm and a fiber length of 5 μm to 1,000 μm, on the gas diffusion layer, followed by drying to prepare a carbon layer;
• applying a coating fluid containing a catalyst and an ion exchange resin thereon, followed by drying to prepare the catalyst layer;
• then heating and pressing the applied surface while the surface is adjacent to the electrolyte membrane, thereby hot-pressing the catalyst layer on the surface of the electrolyte membrane to prepare at least one of the above cathode and the above anode, wherein the carbon nanofibers and the fluorinated ion exchange resin are contained in a mass ratio of from 1:0.1 to 1:5 in the carbon layer.