Patent ID: 7279539

Claim:
A polymer, which contains a structural unit having a carboxyl group represented by the following formula (1) at a side chain of the structural unit; and which comprises a functional group represented by the following formula (2) at a side chain of the polymer, the functional group being capable of changing to an acid group through hydrolysis with alkali: wherein in formula (1), R 1 represents a hydrogen atom or a methyl group; R 2 represents a (n+1)-valent organic linking group containing an ester group represented by —O(C═O)—; A represents an oxygen atom or —NR 3 —; R 3 represents a hydrogen atom, or a monovalent hydrocarbon group having from 1 to 10 carbon atoms; and n indicates an integer of from 1 to 5; and in formula (2), Q represents a linking group that links X 1 to a main chain of the polymer; X 1 represents a protective group hydrolyzable with an alkali aqueous solution having a pH of 10 or more; and when the functional group represented by the formula (2) gives —Q—OH after hydrolysis, the —Q—OH is an acid group having a pKa of 10 or less.