Method for manufacturing a cross-linked thermoplastic resin foam

A method for continuously manufacturing a cross-linked thermoplastic resin foam, comprising:

• extruding a resin composition into a closed die, said resin composition containing at least a thermoplastic resin, a foaming agent, and a cross-linking agent, said die including at least a molding region, a heating region, and a cooling region, continuously arranged in the order named;
• molding said resin composition into a desired shape in said molding region of said die;
• heating said resin composition in said heating region of said die to decompose said cross-linking agent and also to decompose 20 to 95% of said foaming agent so that cell nuclei are produced, thereby forming a partially foamed product;
• cooling said partially foamed product to a temperature lower than the softening point thereof in said cooling region of said die, thereby increasing the rigidity of said partially foamed product, and extruding said partially foamed product, moving in said cooling region, to the outside of said die while applying a damping force to said partially foamed product;
• and
• heating the extruded partially foamed product under atmospheric pressure to complete the decomposition of the foaming agent and the expansion of the extruded partially foamed product, thereby continuously obtaining a final product.