| 摘要 |
PURPOSE:To produce an acetal copolymer excellent in impact and fatigue resistances, by polymerizing formaldehyde in the presence of a specified elastomer having at least one carboxylic acid anhydride group. CONSTITUTION:Use is made of a thermoplastic elastomer having both soft and hard segments, a secondary transition point of --40 deg.C, and at least one carboxylic acid anhydride group, e.g., itaconic anhydride-modified ethylene/propylene copolymer containing one carboxylic acid anhydride group, or maleic anhydride-modified polystyrene/polyisoprene block polymer containing two carboxylic acid anhydride groups. Namely, formaldehyde is polymerized in the presence of the above oligomer and about 0.0005-5pts.wt., per 100pts.wt. starting materials, anion polymerization catalyst. Alternatively, formaldehyde or polyoxymethylene is copolymerized with a cyclic ether in the presence of a cation polymerization catalyst.
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