US 5,340,844 A · Polystyrene foam and a process for making the same

Abstract

An improved polystyrene foam having less corrugation is disclosed which uses carbon dioxide as the blowing agent and 1-30 weight percent endothermic agent, such as water, with the weight based on the total carbon dioxide blowing agent and endothermic agent weight. This combination of carbon dioxide and endothermic agent decreases the corrugation of the thermoplastic foam, while just slightly increasing density, when the process parameters, including throughput, are equivalent to using only carbon dioxide. The process an also allow an increased foaming temperature and greater process throughput of an equivalent density thermoplastic foam at approximately equivalent corrugation levels when compared to the use of only using only carbon dioxide.

Claims45

Dependent claims

A thermoplastic foam comprising:

(a) a styrenic polymer;
(b) a blowing agent consisting essentially of carbon dioxide;
and
(c) an endothermic agent present in an amount from about one percent to about thirty percent by total weight of the carbon dioxide and the endothermic agent;
and
(d) a nucleating agent in an amount of about 0.005 to about 1.0 weight percent based on styrenic polymer weight;
wherein any blowing agent consists essentially of carbon dioxide, and wherein the thermoplastic foam has less corrugation than a thermoplastic foam produced under equivalent process conditions without the endothermic agent.

4 more elements

Dependencies are inferred from the claim text.

Polystyrene foam and a process for making the same

Life of this patent

Polystyrene foam and a process for making the same

Life of this patent

Abstract

Claims45