Patent ID: 8163839

Claim:
A process for the production of a pigment dispersant, which comprises: polymerizing (a′) 5 to 30 wt % of at least one of an aromatic vinyl monomer and a heterocyclic vinyl monomer, (b′) 10 to 30 wt % of a monomer having an acid group, (c′) 40 to 80 wt % of a (meth)acrylate ester monomer, and (d′) 5 to 30 wt % of a monomer having a poly(C 2-6 -alkylene glycol) chain or mono(C 1-22 -alkyl) ether chain of said glycol, said poly(C 2-6 -alkylene glycol) chain or mono(C 1-22 -alkyl) ether chain having a number average molecular weight of from 150 to 1,500, a sum of said monomers (a′) to (d′) amounting to 100 wt %, with a polymerization initiator in a water-soluble organic solvent to obtain a polymerization mixture with a resultant polymer contained therein, combining and mixing said polymerization mixture and water together to emulsify or dissolve said polymer in said water such that an emulsion or solution of said polymer is obtained, adding an acid to said emulsion or solution of said polymer to have said polymer precipitated such that a mixture of water and said polymer is obtained, and then, heating said mixture to a temperature of not lower than a cloud point of said polymer, wherein said polymerization initiator is such that a coupling product of radical decomposition products of said polymerization initiator has a boiling point of not lower than 250° C.