Fast-cooling styrene polymer foams

Claim 1

Method of making foamable styrene polymer particles which yield a fast cooling foamed molding comprising the steps of: (a) suspending styrene polymer particles in water with the aid of a suspending agent system; (b) adding 3 to 20 weight percent of a blowing agent and 0.1 to 0.6 weight percent of a synergistic mixture of (1) a first surfactant selected from the group consisting of polyoxyethylene sorbitan monoesters of fatty acids, polyoxyethylene monoesters of fatty acids, and polyoxyethylene monoethers of long-chain fatty alcohols and (2) a second surfactant selected from the polyoxyethylene monoethers of alkylphenols, wherein the polyoxyethylene moieties contain from 10 to 50 moles of ethylene oxide per molecule, the fatty acids and alcohols contain from 10 to 18 carbon atoms per molecule, and the alkyl portion of the alkylphenols contains from 8 to 12 carbon atoms wherein said synergistic mixture consists of a ratio of said first surfactant to said second surfactant of between 3 to 1 and 1 to 1; (c) heating the suspension at a temperature of from 80° to 150° C. to impregnate the polymer particles with blowing agent and the mixed surfactants; and (d) separating the impregnated particles from the aqueous system.