Manufacturing method for gas diffusion sheet

A manufacturing method for a gas diffusion sheet of a fuel cell in which a porous layer containing a conductive particle is formed on a conductive belt-shaped base material while the base material is conveyed by a roll-to-roll method, the manufacturing method comprising:

• joining a first film for conveyance to a front end portion of the base material in a conveyance direction, the front end portion serving as an unwinding start part of the base material that is wound in a roll shape;
• guiding the base material while the base material is conveyed as the first film is conveyed by the roll-to-roll method, and coating a surface of the base material with a paste material that contains at least the conductive particle;
• manufacturing the gas diffusion sheet as the porous layer is formed as the paste material applied is heated while the base material coated with the paste material is continuously conveyed;
• and
• joining a second film for conveyance to a rear end portion of the base material in the conveyance direction, the rear end portion serving as an unwinding end part of the base material, wherein:
• after the first film is wound, the gas diffusion sheet joined to the first film is wound, and further, the second film joined to the gas diffusion sheet is wound;
• for joining of the first film, a first joining material is made to penetrate a first overlapping portion where the first film and the base material are superimposed on each other, and the first film and the base material are thus physically joined to each other through the first joining material;
• and
• for joining of the second film, a second joining material is made to penetrate a second overlapping portion where the base material and the second film are superimposed on each other, and the second film and the base material are thus physically joined to each other through the second joining material;
• wherein the first joining material penetrates are arranged along both sides of the first overlapping portion and the first joining material penetrates for each side are arrayed in the conveyance direction, and the second joining material penetrates are arranged along both sides of the second overlapping portion and the second joining material penetrates for each side are arrayed in the conveyance direction.