Preparation of acrylic polymer sol for coating

A method for preparing acrylic polymer beads for automobile, which beads have an average particle diameter of 0.2 to 0.5 μm and a standard deviation of particle diameter of 1 to 12% with respect to the average particle diameter as measured with a Submicron Particle Sizer in an emulsion obtained by emulsion polymerization, the final average particle diameter after spray drying being 10 to 100 μm, the method comprising:

• (a) adding an ion-exchange water, 5 to 60 wt.% of a monomer constituting a core layer, and an emulsifier to a reactor, heating the reactor, adding an aqueous initiator, and performing polymerization to form seeds;
• (b) adding dropwise the rest of the monomer constituting the core layer, and further performing polymerization to form a core layer;
• (c) adding a monomer constituting a shell layer, and further performing polymerization to form an emulsion containing acrylic polymer beads having a core/shell structure;
• and
• (d) spray-drying the emulsion containing acrylic polymer beads to prepare acrylic polymer beads.