Aqueous crosslinkable polymer dispersions with improved stability

摘要

A long-shelf life aqueous coating composition, comprising water-dispersed polymer binder, such as an acrylate polymer binder, with a carbonyl-hydrazide cross-linking system, such as adipic dihydrazide, and one or more volatile mono-carbonyl entities, such as mono-ketones, such as methyl ethyl ketone, methyl iso-butyl ketone, mono-aldehydes and mixtures thereof (which retard cross-linking). Also disclosed is a long-shelf life cross-linkable vinyl copolymer dispersion comprising an aqueous solution of a water-soluble oligomer having a number average molecular weight Mn within the range of from 500-50,000 and a glass transition temperature (Tg) within the range of 10-150°C, and which oligomer is derived from a monomer system comprising 1-45 weight % of acid co-monomer(s), 0.5 to 20 weight % of crosslinking co-monomer(s), and 98.5-50 weight % of non-acid functional, non­-crosslinking co-monomer(s), the oligomer having cross-linkable carbonyl or hydrazide functional groups. The dispersion optionally comprises an aqueously dispersed hydrophobic polymer having a number average molecular weight Mn, higher than that of the oligomer, the dispersed polymer optionally having functional groups for imparting crosslink ability; a polyhydrazide or polycarbonyl crosslinking agent being react-able with the crosslinker functional groups of the oligomer and one or more volatile mono-carbonyl entities reversibly reactive with the hydrazide cross-linking groups (which retard crosslinking). A wood stain formulation comprising the long-shelf life aqueous coating composition is also disclosed.