| 摘要 |
PROBLEM TO BE SOLVED: To provide a block copolymer preferably used for forming an adhesive layer of a surface protection film satisfying adhesive properties such as initial adhesive property, low adhesive disease resisting property, easy detachability and low expanding force.SOLUTION: There is provided a block copolymer containing copolymer blocks A to C and having a block structure represented by the formula (1): C-A-B-A-C, where A is a copolymer block containing consecutive aromatic alkenyl compound units having the content of 80 mass% or more, B is a conjugated diene-aromatic alkenyl compound copolymer block having a conjugated diene unit and an aromatic alkenyl compound unit randomly, C is at least one kind selected from a block C1 having consecutive conjugated diene unit having the content of over 80 mass% and a block C2 of which the content of the conjugated diene unit and the content of the aromatic alkenyl compound unit are changed taper shape. |
