Lightly crosslinked polymeric foams and process for making same
OwnerToshimichi Yamazakiinventor
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Abstract
A lightly crosslinked polymer foam and a process for its production, wherein the crosslinking occurs in the extruder, which comprises melt processing an olefinic polymer, with a volatile blowing agent, a free-radical generating peroxide as a crosslinking agent, and an antioxidant as a countervailing agent.
Claims12
A process for the preparation of a lightly crosslinked polymer foam material, comprising the steps of:
- (a) melt processing an olefinic polymer, together with a volatile blowing agent, a sufficient amount of a free radical generating peroxide as a crosslinking agent, said peroxide having a decomposition temperature at a one minute half-life of about 130.degree. C. or greater, the ratio of said peroxide to said olefinic polymer being from about 1 ppm to about 20,000 ppm, and an antioxidant as a countervailing agent to terminate the free radical crosslinking reaction, the weight ratio of said antioxidant to said peroxide being from about 0.01 to about 50.0 wt./wt. to form a flowable admixture;
- and
- (b) extruding said admixture through a die to a zone of lower pressure and activating said blowing agent to expand the polymer to form a cellular lightly crosslinked polymer foam material.
An expandable polymeric composition comprising an olefinic polymer, a free radical generating peroxide as a crosslinking agent, said peroxide having a decomposition temperature at a one minute half-life of about 130.degree. C. or greater, the ratio of said peroxide to said olefinic polymer being from about 1 ppm to about 20,000 ppm, an antioxidant as a countervailing agent to terminate the free radical crosslinking reaction, the weight ratio of said antioxidant to said peroxide being from about 0.01 to about 50.0 wt./wt., and a volatile blowing agent.
Dependencies are inferred from the claim text.