Crosslinked polyolefin foam containing a high concentration of an inorganic material and process for producing the same

A process for producing a crosslinked foam containing a high concentration of an inorganic material and having a high expansion ratio which comprises, heating an expandable composition containing 100 parts by weight of a resin component consisting of a non-crystalline ethylene-vinyl acetate copolymer having a vinyl acetate content in the range of 40 to 90% by weight or a blend thereof with an amount of not more than 80% by weight of at least one compatible thermoplastic resin, 50 to 500 parts by weight of an inorganic powder material which is at least one powder selected from the group consisting of aluminum hydroxide powder and magnesium hydroxide powder, 5 to 50 parts by weight of a blowing agent and 0.1 to 10 parts by weight of a crosslinking agent, the water content of said expandable composition being not higher than 0.15% by weight.

A process for producing an ethylene-vinyl acetate copolymer foam containing an inorganic material characterized in that a composition containing 100 parts by weight of a resin component consisting of a non-crystalline ethylene-vinyl acetate copolymer having a vinyl acetate content in the range of 40 to 90% by weight or a blend thereof with an amount not more than 80% by weight of a thermoplastic resin, 50 to 500 parts by weight of an inorganic powder material which is at least one powder selected from the group consisting of aluminum hydroxide powder and magnesium hydroxide powder and 5 to 50 parts by weight of a blowing agent is molded, crosslinked by irradiation with ionizing radiation, and foamed by heating at a temperature higher than the decomposition temperature of the blowing agent.