Patent ID: 8586687

Claim:
A polyalkylene glycol-based polymer comprising: a structure unit (a) derived from a polyalkylene glycol-based monomer (A); and a structure unit (b) derived from a carboxyl group-containing monomer (B); the polyalkylene glycol-based monomer (A) represented by the formula (1): wherein R 1 represents H or a methyl group; X represents a methylene group, an ethylene group, or a direct bond; n represents an average addition number of moles of an oxyalkylene group (—R 2 —O—), and is from 1 to 300; R 2 represents an ethylene group; m represents an average addition number of moles of an oxyalkylene group (—R 3 —O—), and is from 3 to 10; R 3 represents a C 3-4 alkylene group, and each of R 3 s may be the same as or different from each other; and R 4 represents H, a C 1-24 alkyl group, or a C 6-24 aryl group, wherein the structure unit (a) is present at a level of from 10 to 70% by mass based on 100% by mass of all structure units derived from all monomers in the polymer, and the structure unit (b) is present at a level of from 30 to 90% by mass based on 100% by mass of all the structure units derived from all the monomers in the polymer, and wherein out of 100 mol % of all the oxyalkylene groups represented by (—R 2 —O—) and (—R 3 —O—) in the formula (1) in the polyalkylene glycol-based monomer (A), C 3-4 oxyalkylene groups constitute 1 to 90 mol %.