Patent ID: 7317056

Claim:
A process for producing a synthetic resin emulsion comprising polymer particles having a core and shell structure, said shell including a copolymer of an unsaturated carboxylic acid and a hydrophilic comonomer, said core comprising a copolymer of a core monomer mixture including a radically polymerizable main monomer and a radically polymerizable functional monomer, said process comprising the steps of: providing an unsaturated carboxylic acid and a hydrophilic comonomer; polymerizing said unsaturated carboxylic acid and a hydrophilic comonomer in an aqueous medium to form an aqueous copolymer solution; and adding said core monomer mixture for core formation when the aqueous copolymer solution is in an unneutralized state to form a reaction mixture; concurrently emulsion polymerizing the reaction mixture and adding a pH adjuster to the aqueous copolymer solution, to form a synthetic resin emulsion, wherein said monomer mixture comprises monomers selected so that the glass transition point (Tg) of the core copolymer produced by polymerization is −20° C. or below.