| 摘要 |
1,232,312. Self-extinguishing expandable polymers. FARBWERKE HOECHST A.G. 21 May, 1968 [22 May, 1967], No. 24282/68. Headings C3C and C3P. A self-extinguishing, expandable polymer composition is made by homopolymerizing or copolymerizing in aqueous suspension a monomeric material comprising from 55 to 100% by weight of one or more monoalkenyl aromatic monomers having the general formula in which Ar is a monovalent aromatic radical and R is a hydrogen atom or a methyl group, and from 0 to 45% by weight of one or more other ethylenically unsaturated monomers, the polymerization being carried out in the presence of an amount of one or more tetrabromobutanes as a self-extinguishing agent such that the homopolymer or copolymer produced has from 0À4 to 2À0% by weight, based upon the weight of the homopolymer or copolymer, of the tetrabromobutane(s) admixed therewith, a blowing agent being introduced at any stage of the process so that the homopolymer or copolymer formed has the blowing agent incorporated therein. The blowing agent may be pentane. The expandable polymer beads may be coated with a metal, e.g. Mg, Zn or Ca, stearate prior to pre-expansion. |
