Patent ID: 8476341

Claim:
A multi-branched polymer, comprising: a polyalkylene glycol chain; a residue of a compound having three or more active hydrogen atoms; and a polymer portion having a constitutional unit derived from a vinyl monomer component, one end of the polyalkylene glycol chain bonding to the residue, and a terminal oxygen atom of at least one of the other ends of the polyalkylene glycol chain bonding to a main chain end of the polymer portion directly or via an organic residue, wherein said multi-branched polymer is represented by the following formula (1): wherein X is a residue of the compound having three or more active hydrogen atoms; each AO is a C2-C18 oxyalkylene group, and the AOs may be the same as or different from each other; each Y 1 is a direct bond or an organic residue; each Z is a polymer portion having a constitutional unit derived from a vinyl monomer component; each n is the average number of moles of the oxyalkylene groups added and is 5 to 1,000, and the ns may be the same as or different from each other; and m is an integer of 3 to 50.