METHOD FOR PREPARING BLOCK COPOLYMER EXCELLENT IN COLOR AND HEAT RESISTANCE

摘要

PURPOSE: Provided is a method for preparing a block copolymer, which overcomes existing yellowing problem and simultaneously improves heat resistance of resulting block copolymer, without affecting its preparation process. CONSTITUTION: The method comprises the steps of: (i) adding monoester phosphate represented by formula 1 or diester phosphate represented by formula 2 alone, or mixture thereof as polymerization terminator, in order to remove activities of living polymer prepared from vinyl aromatic monomer and organic lithium initiator by anionic polymerization and those of living copolymer prepared from isoprene monomer to terminate a reaction; and (ii) adding an antioxidant in order to prevent an oxidation of the polymer or copolymer(from which activities are removed). In the formulae, R represents an alkyl or alkyl aryl group of C1-C20, and n is an integer of 2-20.