Patent ID: 7115690

Claim:
A fluorine-containing polymer having an aliphatic monocyclic structure in the polymer trunk chain which has a number average molecular weight of from 500 to 1,000,000 and is represented by the formula (Mb): -(M1)-(M2b)-(N)— (Mb) in which the structural unit M1 is a structural unit derived from an ethylenic monomer having 2 or 3 carbon atoms and at least one fluorine atom, the structural unit M2b is at least one structural unit which introduces an aliphatic monocyclic structure in the polymer trunk chain and is represented by the formula (b): wherein R 1 is at least one hydrocarbon group selected from the group consisting of a divalent hydrocarbon group which has 1 to 8 carbon atoms and constitutes a ring (which may be further substituted with a hydrocarbon group or a fluorine-containing alkyl group) and a divalent hydrocarbon group having ether bond which has the sum of carbon atoms and oxygen atoms of 2 to 8 and constitutes a ring (which may be further substituted with a hydrocarbon group or a fluorine-containing alkyl group); R 2 is an alkylene group which has 1 to 3 carbon atoms and constitutes a ring; R 3 and R 4 are the same or different and each is a divalent alkylene group having 1 or 2 carbon atoms; n1, n2 and n3 are the same or different and each is 0 or 1; Z are the same or different and each is: R 5 n5 Z 1 wherein Z 1 is at least one functional group selected from the group consisting of OH group, COOH group, a derivative of carboxylic acid group and a functional group protected by a protective group which can convert the functional group to OH group by reaction with an acid; R 5 is a divalent organic group; n5 is 0 or 1; n4 is an integer of from 1 to 3, the structural unit N is a structural unit derived from a monomer copolymerizable with the monomers to introduce the structural units M1 and M2a, and the structural units M1, M2b and N are contained in amounts of from 1 to 99% by mole, from 1 to 99% by mole and from 0 to 98% by mole, respectively.