Patent ID: 7423075

Claim:
A polymer that comprises a repeating structural unit represented by the following general formula (1) and a repeating structural unit represented by the following general formula (2): wherein A represents a substituted or unsubstituted polyalkenyl group; B represents any one of structures selected from —O—, —OCO—, —COO—, CONR 1 — and —CH 2 —, where R 1 represents a hydrogen atom or a substituted or unsubstituted straight-chain or branched alkyl group having 1 to 3 carbon atoms; D represents a substituted or unsubstituted straight-chain or branched alkylene group having 1 to 15 carbon atoms, and the methylene group in the alkylene group may be substituted by an oxygen atom or an aromatic ring; m represents an integer of 0 to 30 and, when m is 2 or more, each D may be different; E represents a substituted or unsubstituted aromatic ring; n represents an integer of 0 to 10 and, when n is 2 or more, each E′ may be different; provided that m+n is 1 or more; and R represents —SO 3 H, SO 3 R 2 or —SO 3 —M, where R 2 represents a substituted or unsubstituted straight-chain or branched alkyl group having 1 to 5 carbon atoms or a substituted or unsubstituted aromatic ring, and M represents a monovalent or polyvalent cation; and wherein A represents a substituted or unsubstituted polyalkenyl group; B′ represents any one of structures selected from —O—, —OCO—, —COO— and CONR 1 , where R 1 represents a hydrogen atom or a substituted or unsubstituted straight-chain or branched alkyl group having 1 to 3 carbon atoms; D represents a substituted or unsubstituted straight-chain or branched alkylene group having 1 to 15 carbon atoms, and the methylene group in the alkylene group may be substituted by an oxygen atom or an aromatic ring; m represents an integer of 0 to 30 and, when m is 2 or more, each D may be different; E′ represents a substituted or unsubstituted alkyl group or aromatic ring; n′ represents an integer of 1 to 10 and, when n is 2 or more, each E′ may be different; R′ represents —COOH, —COO 2 or —COO-M, where R 2 represents a substituted or unsubstituted straight-chain or branched alkyl group having 1 to 5 carbon atoms or an aromatic ring, and M represents a monovalent or polyvalent cation; and l is 1 or more, wherein the polymer is a block polymer having at least two block segments, and at least one block segment of the block polymer contains a copolymerization composition of the repeating structural unit represented by the general formula (1) and the repeating structural unit represented by the general formula (2).