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AssigneeFirma Carl Freudenberg
InventorErnst Lohmar
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This application is directed to light-weight and hard foam materials. The foams of this invention are prepared by extruding thermoplastic crystalline plastics in the presence of highly volatile organic liquids as the foaming agents. In accordance with the present method crystalline polyolefins, in the presence of polybutadiene, ethylenevinylacetate copolymers, ethylene-propylenes and/or ethylene-propylene terpolymer rubbers, and optionally radical formers such as suitable peroxides, azidene, sulfonyl azidene or the like, and inhibitors for radical decomposition, such as triallylcyanurate or an acrylate selected from the group consisting of trimethylolpropane-trimethacrylate, allyl-methacrylate, tetrahydrofurfurylmethacrylate, triethyleneglycol-dimethacrylate, polyethyleneglycol-dimethacrylate or the like, are converted into foam-like molded bodies by means of a highly volatile organic liquid foaming agent. The foaming agent is employed in an amount of from about 5 to about 30% by weight, based on the weight of the polyolefins. The foaming agent and the polyolefins are mixed in an extruder at a temperature of from about 180.degree. to about 280.degree. C., and at a pressure which is greater than the vapor pressure of the foaming agent. The mixture is subsequently extruded.
A method of preparing a lightweight foam material which comprises:
A method of preparing a light-weight foam material which comprises:
A method of preparing a light-weight foam material which comprises:
Dependencies are inferred from the claim text.