| 摘要 |
1,189,500. Foamed cross-linked propylene polymers. TOYO RAYON K.K. 28 Dec., 1967 [28 Dec., 1966; 30 Dec., 1966; 15 May, 1967; 22 Aug., 1967], No. 58942/67. Headings C3C and C3P. Foamed propylene polymers which are crosslinked with 0À05-20% by wt. of divinylbenzene are claimed which may be prepared either by heating a mixture of the propylene polymer, divinylbenzene an organic free-radical forming agent and a foaming agent, which liberates gas on heating to its decomposition or volatilization temperature, so as to cross-link and foam the polymer, or by treating the above mixture (less free-radical agent) with radiation of a wavelength shorter than visible light at a temperature lower than the softening point of the propylene polymer and then heating the mixture to a temperature above the softening point and above the gas-generating temperature of the foaming agent. The propylene polymer may be isotactic or crystalline polypropylene or an ethylene-propylene copolymer which may be a block copolymer and may be compounded with an ethylene-vinyl acetate copolymer, polybutadiene or polyethylene. The foaming agent may be barium azodicarbonamide, bisbenzenesulphonyl hydrazide, dinitropentamethylenetetramine, barium azodicarboxylate or ptoluene sulphonyl semicarbazide The freeradical agent may be dicunyl peroxide, 2,5-dimethyl - 2,5 - bis(t - butylperoxy) - hexene, dit - butyl - perterephthalate. The divinylbenzene may contain vinyltoluene. The polymer may be formed into a sheet. |
