Prepn. of non-crosslinked recyclable foam - using grafted copolymer of ethylene contg. acrylate ester of sec. or tert alcohol

摘要

A polymer foam is prep from a grafted copolymer of ethylene. The copolymer contains 60-90 wt.% ethylene, 10-40 wt.% of an acrylate ester of a secondary or tertiary alcohol and opt. up to 10 wt.% of further monomers, and is grafted with 0.1-5 wt.% of an ethylenically unsaturated mono- and/or dicarboxylic acid and/or an ethylenically unsaturated dicarboxylic anhydride. The polymer is heated for 5-90 mins. at 200-300 deg.C in the absence of oxygen. Pref. the original polymer contains 70-80 wt.% ethylene, 20-30 wt.% acrylate ester and up to 5 wt.% of other monomers. The alcohol of the acrylate ester contains 3-12, pref. 4-10 and esp. 4-6 carbon atoms. The further monomers are methyl acrylate and/or vinyl acetate. The original polymer is grafted with 0.3-4, pref. 0.5-3 wt.% of unsat acid or anhydride, which is maleic anhydride and/or fumaric acid and/or acrylic acid. ADVANTAGE - Gives an uncrosslinked, recyclable, foam.