PURPOSE: To provide a binder compsn. which has improved open time and stability and is useful for low energy curable coatings, binders, adhesives and the like by including an acid copolymer emulsion and a halohydroxypropylammonium salt copolymer soln.

CONSTITUTION: An ethylenically unsatd. carboxylic acid (a) in an amt. of 0.1 to 20 wt.% and a comonomer (b), such as methyl methacrylate, an acrylate of a 1-4C alcohol, vinyl acetate, or styrene, are polymerized in the presence of a nonionic surfactant in a solvent to obtain an acid copolymer emulsion (A). Separately, not less than 6 wt.%, pref. not less than 90 wt.% quaternary ammonium monomer (c) represented by formula I or II (wherein R represents an ethylenically unsatd. group; R1 represents a 1-4C alkyl or hydroxyalkyl; X represents Cl, Br, or I; and Y- represents an anion) and an optional ethylenically unsatd. monomer (d) excluding an acid (anhydride) are polymerized in a solvent to obtain a halohydroxypropylammonium polymer soln. (B). The component (A) is formulated with the component (B) in an amt. of (1:1,000) to (1:1) in terms of the component (B) to component (A) ratio (polymer solid basis).