PURPOSE: To obtain a coating composition composed of an emulsion obtained by the emulsion polymerization of an α,β-ethylenic monomer in the presence of a specific polymerizable emulsifier, a pigment and a specific amount of colloidal silica, having excellent thermal blocking resistance and exhibiting excellent stability.

CONSTITUTION: This composition is composed of (A) an emulsion produced by the emulsion polymerization of an α,β-ethylenic monomer (e.g. methyl acrylate and styrene) in the presence of a polymerizable emulsifier of the formula I (A is 2-4C alkylene; R1 is H or methyl; R2 is 8-24C hydrocarbon group or acyl; m is 0-50; Z is H or nonionic or anionic hydrophilic group), (B) a pigment mixture and (C) colloidal silica (preferably having particle diameter of 5-50nm) of an amount satisfying the formula II and 5≤X≤9O (Y is defined by the formula III; X is defined by the formula IV). The pH of the composition is preferably ≥8.5.