Method of molding a rigid integral skin foamed resin product in a mold having a vented lid

Claim 1

In the method of molding a rigid foam plastic article using a mold box having an apertured molding cavity therein and a lid for covering said aperture and characterized by the steps of (1) depositing foamable plastic material in said molding cavity; (2) covering said cavity with said lid; (3) permitting said foamable plastic to foam and expand into contact with the walls of said molding cavity; and (4) demolding the resulting molded foam plastic article, the improvement comprising the steps of: disposing between said lid and said mold box, covering said cavity, a breathable layered structure consisting essentially of breathable paper laminated to a support sheet for providing support against sagging, said paper having a textured, release-treated surface positioned for contacting said foamable plastic when said plastic foams and expands, said layered structure exhibiting sufficient gas porosity to enable substantially complete venting of the mold cavity through said layered structure outwardly between the mold box and the lid during foaming of plastic material deposited therein while precluding exudation of such material therethrough; molding the surface of said foam plastic article beneath said breathable layered structure to provide a hard-skinned, textured, finished outer surface substantially free of visible wrinkles, gas pockets, or bubbles by (a) supporting said paper against sagging into said mold cavity; (b) permitting said foamable plastic to foam and expand into intimate molding contact with said release-treated surface; and (c) venting entrapped gas laterally through said breathable layered structure out of the mold between said lid and said mold; and peeling said breathable layered structure from said molded plastic article thereby exposing said hard-skinned, finished outer surface.