| 摘要 |
1331041 Foamed olefin polymers T N ATKINSON 24 Sept 1970 [24 June 1969] 31895/69 Heading C3C Polymers and copolymers of olefines, particularly polyethylene and polypropylene, are foamed by heating the polymer with an organic peroxide and a heat-decomposable blowing agent, said heating being effected by contacting the mixture with a hot liquid (e.g. a fused salt bath) or a hot fluidized bed. The resultant foams contain at least 75% of the total cell number of closed cells; specified peroxides are dicumyl peroxide, 2,5-dimethyl-2,5-di-(t-butylperoxy) - hexane, di - t - butyl - perterephthalate and t-butyl hydroperoxide; specified blowing agents are p,p<SP>1</SP>-oxybisbenzenesulphonylhydrazide, azodicarbonamide and dinitrosopentamethylenetetramine, and the foaming is normally conducted at 150-280‹ C., preferably in two stages: (i) at 120-190‹ C., (ii) at 150- 270‹ C.; the second stage being at a higher temperature. Additives that may be present include ethylene/vinyl acetate copolymer, ethylene/acrylate copolymer, natural and/or synthetic rubbers, zinc oxide, sodium lauryl sulphate, stearic acid, mica, antimony oxide and chlorinated materials. The process may be effected in a mould or by continuous extrusion through a bath of the hot liquid. |
