Patent ID: 6894114

Claim:
A block copolymer: (a) being an anionic polymerization product; (b) comprising two or more polymer blocks A being miscible with each other, and at least one (meth)acrylic ester polymer block B being immiscible with the polymer blocks A; (c) having a ratio [Mn(A max )/(Mn(A min )] of 2 or more, where the ratio [Mn(A max )/(Mn(A min )] is the ratio of the largest number average molecular weight [Mn]A max )] to the smallest number average molecular weight [Mn]A min )] among the two or more polymer blocks A; (d) having at least one block bonding represented by formula (I): (—)A max —B—A min (—) (I) wherein A max is the polymer block A max having the largest number average molecular weight among the polymer blocks A; A min is the polymer block A min that has the smallest number average molecular weight among the polymer blocks A; B is the polymer block B; “—” is a chemical bond connecting polymer blocks; and (—) indicates the optional presence of a chemical bond; and (e) having a total content of polymer blocks A ranging from 20 wt % to 45 wt % of the total weight of the block copolymer.