Patent ID: 8729187

Claim:
A copolymer comprising repeating units represented by formula (I), formula (II), and formula (III): wherein R 1 , R 2 , and R 3 each independently represent a hydrogen atom or a methyl group; R 4 represents a linear or branched alkyl group, or a linear or branched alkyl group that is substituted by hydroxy group; R 5 represents a hydrogen atom or a C 1 to C 6 alkyl group; m, n and k represent a molar ratio of the respective repeating units; m , n and k each independently represents a positive number of more than 0 and less than 1, and satisfy a relation of m+n+k=1, and having a weight-average molecular weight in the range of 50,000 to 200,000, wherein two blocks consisting of the block comprising the repeating units represented by formula (I) and formula (II) and the block comprising the repeating unit represented by formula (III) are bonded by block bonding.