VINYL POLYPIVALATE POLYMER COMPOSITION AND METHOD FOR PRODUCING THEREOF

摘要

PURPOSE: A vinyl polypivalate polymer composition is provided, which has a high syndiotacticity to be useful as a precursor of polyvinyl alcohol with high syndiotacticity. Also, a method for producing such vinyl polypivalate polymer is provided. CONSTITUTION: The vinyl polypivalate polymer composition is obtained by adding tetrahydrofuran as a polymerization solvent to vinyl pivalate, followed by stirring; passing nitrogen at a high pressure; raising the temperature for polymerization; adding azobisdimethyl valeronitrile as an initiator to the solution under nitrogen atmosphere for solution polymerization of vinyl polypivalate polymer having a number average polymerization degree of 200 to 20,000, a content of syndiotacticity diad group of 55 to 70 %, and a branching level to pivaloyl group of 0.5 to 3.0. The molar ratio of azobisdimethyl valeronitrile as an initiator to 1 mole of vinyl pivalate is 1 x 10¬-5 mole to 5 x 10¬-3 mole and the tetrahydrofuran as a solvent is 0.05 mole to 5.0 mole.