JPS5761783B

PURPOSE:The titled antisettling agent for a solvent type coating material containing large amounts of pigment of poor dispersibility and PVC, etc. prepared by polymerizing a plurality of polymerizable monomers of specific structure in the presence of an emulsifier and a dispersing agent, and then dropping and polymerizing acrylonitrile with the resultant polymer. CONSTITUTION:(ii) A polymerizable monomer expressed by the formula [X is H, Cl or methyl; Y is Cl, acetoxy, phenyl or ROOC- (R is 1-4C alkyl)], preferably methyl methacrylate, (iii) a polymerizable monomer containing a cyano group and (iv) other kinds of monomers are polymerized in the presence of (i) an emulsifier and/or a dispersing agent to form (A) an aqueous dispersion. (B) Acrylonitrile or a mixture containing 20wt% or less the component (ii) or (iii) is dropped to and polymerized in the dispersion to give a spherical polymer particle of particle size 0.5-1mu. The weight ratio of the components (ii)/(iii)/(iv) is 33-80/67-20/0 or that of (ii+iii)/iv is >=90/10, and the amount of the component (B) is 10- 100wt% based on the component (A).