Polymer particle, polymer dispersion, method for producing said polymer dispersion, coating material produced from said polymer dispersion, and coated article

Abstract

A method for producing a polymer dispersion, by polymerizing a mixture X containing a urethane resin (A3), a monomer (b5) having two or more radically polymerizable groups, and a radically polymerizable monomer (b6) other than the monomer (b5), to obtain a dispersion containing a polymer P; and adding a pre-emulsion prepared by emulsifying and dispersing a radically polymerizable monomer mixture Y dropwise to the dispersion containing the polymer P and conducting polymerization, to obtain a dispersion containing a polymer Z, where a content of the urethane resin (A3) in the mixture X at the time of starting the reaction in the step (1) is from 25 to 95% by mass with respect to a total mass of the mixture X.

1 . A method for producing a polymer dispersion, the method comprising:
 (1) obtaining a dispersion comprising a polymer P obtained by polymerizing a mixture X comprising a urethane resin (A3), a monomer (b5) having two or more radically polymerizable groups, and a radically polymerizable monomer (b6) other than the monomer (b5); and   (2) obtaining a dispersion comprising a polymer Z by adding a pre-emulsion prepared by emulsifying and dispersing a radically polymerizable monomer mixture Y dropwise to the dispersion comprising the polymer P and conducting polymerization,   wherein a content of the urethane resin (A3) in the mixture X at the time of starting the reaction in the step (1) is from 25 to 95% by mass with respect to a total mass of the mixture X.   
     
     
         2 . The method according to  claim 1 , wherein the monomer (b5) having two or more radically polymerizable groups is a radically polymerizable monomer (b5-1) having an allyl group. 
     
     
         3 . The method according to  claim 2 , wherein the radically polymerizable monomer (b5-1) having an allyl group is at least one kind of monomer selected from the group consisting of allyl (meth)acrylate, triallyl isocyanurate, diallyl iso(tere)phthalate, diallyl isocyanurate, and diallyl maleate. 
     
     
         4 . The method according to  claim 1 , wherein a content of the monomer (b5) having two or more radically polymerizable groups in the mixture X is from 0.1 to 10% by mass with respect to a total mass of the mixture X. 
     
     
         5 . A polymer dispersion obtained by the method according to  claim 1 .