Block copolymer and production method for block copolymer

A method for producing a block copolymer, the method comprising:

• performing radical emulsion polymerization in the presence of a RAFT agent while adding chloroprene alone, or chloroprene and another monomer stepwise to synthesize a block of a chloroprene polymer;
• and then performing radical emulsion polymerization of an acrylate alone, or an acrylate and another monomer in a mixture to synthesize a block of an acrylate polymer, wherein a number average molecular weight of the block copolymer is 110,000 or more and a number average molecular weight of the block of a chloroprene polymer is 80,000 or more in total.

A vulcanized product prepared from a rubber composition comprising a block copolymer, wherein the block copolymer comprises one or more blocks of an acrylate polymer and one or more blocks of a chloroprene polymer, wherein a number average molecular weight of the block copolymer is 110,000 or more, a number average molecular weight of the block of a chloroprene polymer is 80,000 or more in total, and the block copolymer has a functional group with a structure represented by the following Chemical Formula (1) or (2):

• wherein, in Chemical Formula (1), R1 represents hydrogen, chlorine, a substituted or unsubstituted alkyl group, a substituted or unsubstituted alkenyl group, a substituted or unsubstituted aryl group, or a substituted or unsubstituted heterocyclyl group.