Patent ID: 7534542

Claim:
A method for producing the binder resin (A) for a toner comprising the following processes (I), (II) and (III) in this order: Process (I): A process comprising melt-mixing a carboxyl group-containing vinyl resin (B) obtained by copolymerizing a vinyl monomer selected from styrene based compounds, acrylic esters, methacrylic esters, diesters of an unsaturated dibasic acid, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, N-substituted acrylamide, and N-substituted methacrylamide, and a vinyl monomer having a carboxyl group selected from acrylic acid methacrylic acid maleic anhydride, maleic acid, fumaric acid, cinnamic acid, and mono esters of an unsaturated dibasic acid and an epoxy group-containing vinyl resin (C) obtained by copolymerizing a vinyl monomer selected from styrene based comnounds, acrylic esters, methacryilc esters, diesters of an unsaturated dibasic acid, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, N-substituted acrylamide, and N-substituted methacrylamide, and a vinyl monomer having an epoxy group selected from glycidyl acrylate, β-methylglycidyl acrylate, glycidyl methacrylate, and β-methylglycidyl methacrylate at a temperature (T R ) satisfying 120° C.≦T R ≦230° C. in a twin screw extruder for the reaction; Process (II): A process comprising introducing water into the twin screw extruder, and mixing water with the resin composition obtained in the Process (I) for 0.1 second to 5 under the conditions satisfying a pressure (P EX ) of 1 MPa≦P EX ≦2.7 MPa and a temperature (T M ) of 120° C.≦T M ≦230° C.; and Process (III): A process comprising reducing the pressure inside the twin screw extruder for removing water and the volatile component.