| 摘要 |
A soft, resilient thermoplastic compsn. comprises a blend of (a) an ethylene copolymer resin, (b) a halogenated butyl rubber, and (c) a polychloroprene rubber, with the rubbers cross-linked by dynamic vulcanisation in presence of the resin. Pref. the comonomer is an alpha,beta-monoethylenically unsatd. monocarboxylic acid or alkyl ester, esp. vinyl acetate, or (m)ethyl or butyl acrylate. A blend of the copolymer with a limited amt. of a polyolefin resin, esp. high- or (linear) low-density polyethylene, propylene (co)polymers, or polybutylene may be used. The resin forms 12-35 wt.% of the compsn. (b) The rubber is a chlorinated and/or brominated butyl rubber, and forms at least 25 (25-65) wt.%, w.r.t. (b)+(c). (c) The polychloroprene forms at least 35 wt.% w.r.t. (b)+(c). Esp., the amts. of (a), (b) and (c) are approximately equal. (d) The compsn. may contain a process oil, in ratio by wt. of oil:rubber of 0.1-1.3:1; the amt. of oil is esp. 10-35 wt.% of the compsn. The compsn. may also contain a filler, esp. 5-30 wt.%, w.r.t. the compsn. The polymer blend esp. forms 40-80 wt.% of the total compsn., the rest being process oil, fillers and curatives.
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