Self cross-linking N-methylol functional emulsion polymers using polycarboxylic acid surfactant

A self cross-linking aqueous emulsion coating composition comprising water having emulsified therein an emulsion polymer comprised of copolymerized monoethylenically unsaturated monomers including, about 6 to about 15 percent by weight of a C.sub.2 -C.sub.8 saturated alcohol ether of a monoehylenically unsaturated N-methylol functional monomer, at least about 50 percent by weight of monoethylenically unsaturated nonreactive monomers, up to about 3 percent by weight of monoethylenically unsaturated carboxylic acids, up to about 25 percent by weight of monoethylenically unsaturated hydroxy functional monomers, and up to about 30 weight percent by weight of polyethylenically unsaturated polymers selected from the group consisting of polyesters, polyepoxy esters, polyepoxy ethers, and mixtures thereof, said monomers and polymer being emulsified by a polymeric carboxylic acid emulsifying agent, said polymeric emulsifying agent being present at about 0.5 to about 10 percent of said monomers and having an average molecular weight in the range of about 600 to about 3000 and containing at least about 25 mole percent of copolymerized monoethylenically unsaturated carboxylic acid, the balance of the monomer in said emulsifying agent being monoethylenically unsaturated monomer of hydrophilic character, said emulsifying agent's polymeric chain being terminated with a mercaptan containing at least 8 carbon atoms, and said polymeric emulsifying agent being partially neutralized with ammonia to a pH of about 5-7.