Method for producing composite resin particles, composite resin particles, molded body using composite resin particles, ink and coating material

A method for producing composite resin particles, the method comprising:

• a first step of obtaining a (A) vinyl chloride-based resin by carrying out emulsion polymerization of a monomer mixture constituted by more than 90 parts by weight and not more than 100 parts by weight of a (a1) vinyl chloride monomer and not less than 0 parts by weight and less than 10 parts by weight of an (a2) ethylenically unsaturated monomer that is copolymerizable with the (a1) vinyl chloride monomer, wherein a total amount of the (a1) and the (a2) is 100 parts by weight;
• a second step of obtaining an (B) acrylic resin by carrying out, in the presence of the (A) vinyl chloride-based resin, emulsion polymerization of a monomer mixture constituted by 50 parts by weight to 100 parts by weight of a (b1) (meth)acrylic acid alkyl ester monomer and 0 parts by weight to 50 parts by weight of an (b2) ethylenically unsaturated monomer that is copolymerizable with (meth)acrylic acid alkyl ester, wherein a total amount of the (b1) and the (b2) is 100 parts by weight,
• a third step, after the second step is finished, comprising adding a (D) hydrazine derivative comprising at least two hydrazino groups or at least two semicarbazide groups per molecule,
• wherein a redox polymerization initiator comprising a polymerization initiator and a reducing agent is used in the second step, and
• wherein the at least one (b2) ethylenically unsaturated monomer used in the second step comprises a carbonyl group derived from a keto group or an aldehyde group.