| abstract |
An object of the present invention is to provide a block copolymer capable of exhibiting well-balanced molding processability, adhesive performance and expandability. When p, q, r, and s are the constituent ratios (molar ratios) of the structural units represented by formulas (1) to (4) in the polymer, they are represented by the formula (i). is a block copolymer having a value α of 0.75 or more, the block copolymer contains 10% by mass or more of a polymer (A1) having a multi-branched structure with 4 or more polymer chains, The combined chain has a polymer block A containing 70% by mass or more of a structural unit derived from a conjugated diene compound and a polymer block B containing 70% by mass or more of a structural unit derived from an aromatic vinyl compound. A block copolymer having a functional group F containing at least one element selected from the group consisting of nitrogen, silicon, oxygen and sulfur at some or all of the terminals of the above polymer chain. α=(p+(0.5×r))/(p+q+(0.5×r)+s) (i) [Selection figure] None |