| 摘要 |
1475443 Foamed polymer films containing diamide BAYER AG 10 Jan 1975 [10 Jan 1974] 1092/75 Heading C3C Foamed films are continuously made from polymers ofα,#-monoolefinically unsaturated monomers by adding to the solid or molten polymer 0À05-0À2% by wt. (based on the polymer) of a diamide made by reacting an aliphatic diamine with at least one aliphatic monocarboxylic acid having at least 4 carbon atoms, in addition to a chemical blowing agent, before or while the polymer is being extruded through an annular die to form a foamed tube which is cut to form a foamed film. The diamide may be of formula where R<SP>1</SP> and R<SP>2</SP> are C 4-20 alkyl or alkenyl groups and n is 2-6, e.g. the diamide of ethylene diamine and lauric, stearic or oleic acid. The polymer may be high or low pressure polyethylene and/or a copolymer of ethylene and up to 20% by wt. of vinyl acetate. The blowing agent may be azodicarbonamide or dinitrosopentamethylene tetramine.
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