Polyacetal block copolymer

摘要

The present invention relates to a polyacetal ABA type block copolymer having a liquid hydrogenated polybutadiene block hydroxyalkylated at both end having a specific monomer structure in the main chain and a polyacetal resin composition comprising the block copolymer and a specific polymer compound or an inorganic filler. The block copolymer and the resin composition can satisfy 4 characteristics necessary for materials for large-diameter gears, i.e. (1) high cycle capability (high productivity), (2) high roundness, (3) distinguished dimensional stability and (4) distinguished durability at the same time and provide useful materials for large-diameter gears having a pitch circle diameter of 60 mm or more.