PURPOSE: To provide the titled compsn. which has excellent storage stability and gives a coating film having good antifouling and mothproof effects, consisting of an acrylic resin contg. a quaternary ammonium salt and an organotin-contg. copolymer.

CONSTITUTION: An acrylic monomer contg. a quaternary ammonium salt [e.g. (meth)acryloyloxyethyltrimethyl ammonium] is reacted with other ethylenically unsaturated monomer [e.g. ethyl (meth)acrylate] to obtain an acrylic resin (A) contg. a quaternary ammonium salt. which has a quaternary ammonium group content of 0.1W3.0m-mol per g of copolymer. A triorg. salt monomer of a monobasic and/or dibasic ethylenically unsaturated carboxylic acid and other ethylenically unsaturated monomer are emulsion-polymerized in an aq. medium to obtain an organotin-contg. copolymer emulsion (B). 5W60wt% component A is mixed with 95W40wt% (on a solid basis) component B.