| 摘要 |
1,219,338. Open-cell ethylene copolymer foams. BADISCHE ANILIN- & SODAFABRIK A.G. 14 June, 1968 [16 June, 1967] No. 28427/68. Headings C3C and C3P. Open-cell ethylene copolymer foams are produced by mixing a copolymer of ethylene and a vinyl ester of a saturated acid or an ester of an unsaturated carboxylic acid in the presence of sulphur and/or a sulphur-containing vulcanization accelerator at a temperature higher than the crystallite m.p. of the copolymer with an expanding agent having a b.p. at least 25‹ C. below the m.p. of the copolymer, the mixing being carried out at a pressure which is higher than the vapour pressure of the expanding agent at the mixing temperature and at a temperature at which cross-linking of the polymer takes place, and bringing the mixture to a temperature in the range from the crystallite m.p. to 20‹ C. below the same immediately prior to extrusion of the mixture into a zone of lower pressure. In examples the copolymer was derived from ethylene and (a) acrylic acid, n- or tert.-butyl acrylate and/or hexyl or cyclohexyl acrylate or (b) vinyl acetate or propionate; the vulcanization accelerator was zinc oxide, stearic acid and dibenzothiazole disulphide, barium oxide, palmitic acid and tetramethyl thiuram disulphide; calcium oxide, stearic acid and diphenylguanidine or zinc oxide, stearic acid and 2-mercaptobenzothiazole; and the expanding agent was isopentane, isobutane, n-butane and/or propane or a halogenated hydrocarbon and talc was used as nucleating agent. |
