Block copolymer containing a methacrylate ester block

Claim 1

A process for producing a block copolymer having a number-average molecular weight of about 1,000 to about 600,000 in which a random copolymer segment (A) is bonded to a polymer segment (B), with the ratio of (A) to (B) being 15/85 to 97/3 by weight, said random copolymer segment (A) being composed of the constitutional units represented by the formulas I and II below ##STR6## wherein the amount of I in said segment (A) is from 30 to 80 wt% and the amount of II in said segment (A) is from 70 to 20 wt%, and said polymer segment (B) being composed of the constitutional units represented by the formula ##STR7## wherein R is hydrocarbyl of from 1 to 20 carbon atoms, said process comprising the steps of: (a) performing living polymerization of ethylene and propylene at a temperature of less than -50° C. in the presence of a catalyst comprising (i) a beta-diketone vanadium chelate of the formula ##STR8## wherein R 1 and R 2 are the same or different and are each alkyl or aryl, and (ii) an organoaluminum compound of the formula R 2 AlX, wherein R is an alkyl group of 1 to 8 carbon atoms and X is a halogen atom, to provide a living ethylene-propylene random copolymer having an ethylene-to-propylene ratio of from 30/70 to 80/20 by weight, said vanadium chelate being used in an amount of from 1×10 -4 to 0.01 mol per 1 mol of said ethylene and propylene, said organoaluminum compound being used in an amount of from about 1×10 -3 to 0.1 mol per 1 mol of said ethylene and propylene, and said organoaluminum compound being used in an amount of from 5 to 25 mol per 1 mol of said vanadium chelate; (b) reacting said ethylene-propylene copolymer with a halogen selected from the chlorine, bromine and iodine to provide an ethylene-propylene random copolymer having halogenated terminal groups, said halogen being employed in an amount of from 2 to 5 moles per mole of said organoaluminum compound; (c) contacting said halogenated copolymer produced in step (b) with metallic magnesium; and (d) polymerizing the product of step (c) with a methacrylate ester of the formula ##STR9## wherein R is as defined above, to form said block copolymer.