Method and foam die for manufacturing seat cushion material

A method for manufacturing a seat cushion material, the seat cushion material including a front layer part disposed on a seating surface side, and a back layer part disposed on a side of the front layer part opposite to the seating surface and having a higher rigidity and a lower density than the front layer part, the seat cushion material having a layered structure in which the front layer part and the back layer part are integrated, and the back layer part having a back side surface constituting at least a part of the surface on the side of the seat cushion material opposite to the seating surface, the method comprising:

• preparing for molding the seat cushion by attaching the back layer part to an upper die having an upper cavity surface corresponding to the surface on the side of the seat cushion material opposite to the seating surface in such a manner that the back side surface is brought into contact with the upper cavity surface;
• molding the seat cushion material by adding foamed resin raw material forming the front layer part on a lower cavity surface of a lower die, and then by closing the upper die to which the back layer part is attached so as to integrate the front layer part with the back layer part, wherein the lower cavity surface of the lower die corresponds to the surface on the seating surface side of the seat cushion material and the lower cavity surface is provided with a plurality of protrusions which is configured to be brought into contact with the seating surface side of the back layer part and is configured to press the back layer part against the upper cavity surface when the upper die to which the back layer part is attached is closed with respect to the lower die;
• and
• demolding the molded seat cushion material.