PROCEDIMENTO PER LA PRODUZIONE DI CORPI FORMATI IN MATERIALE ESPANSO

1497319 Foamed polymeric articles from coated polymer/additive particles SOC ITALIANA RESINE SIR SpA 15 Dec 1975 [20 Dec 1974] 51263/75 Heading C3C A foamed styrene polymer article is made by polymerizing styrene in the presence of a blowing agent and sufficient additive which is (1) a polymer having a mol. wt. of at least 10,000 and is a di- or mono-olefine polymer, styrene/ acrylonitrile copolymer or silicone, or (2) is a halogenated aromatic compound having a b.p. above 200‹ C. at normal pressure, so as to give 0À01-1% by wt. of the additive in particulate the styrene polymer, and then coating the particles with 0À01-1% by wt. (based on the styrene polymer) of (a) an ester of a C 8-20 aliphatic acid with glycerol, sorbitol or ethylene or propylene glycol, (b) an amide of mol. wt. 500-1000 of a C 8-20 aliphatic acid and a polyethyleneamine or polypropylene amine, or (c) ethylene or propylene oxide or an ethylene oxide/propylene oxide condensate of mol. wt. 500-4000 (the step of coating excluding coating with bromophenyl alkenyl ethers), to make expandable particles of styrene polymer which are then pre-expanded, aged and moulded to form the foamed article. In the examples styrene was polymerized in an aqueous suspension containing pentabromophenyl allyl ether and petroleum ether, the beads of polymer were coated with a mixture of glycerol mono- and di-stearate and then pre-expanded, aged and moulded into a block.