Hydroxyalkyl esters in surface coatings

1,168,078. Coating. JEFFERSON CHEMICAL CO. Inc. 5 Oct., 1966 [18 Oct., 1965 (3)], No. 44556/66. Heading B2K. [Also in Divisions C2 and C3] Thermosetting enamels are obtained by crosslinking, by heating with an amino-formaldehyde resin, a copolymer of at least one ethylenically unsaturated compound containing one double bond and a hydroxyalkyl bisester of the formula where A represents the residue of an ethylenically unsaturated dicarboxylic acid, e.g. maleic acid, Z', Z", Q and Q' are hydrogen or a methyl, ethyl, phenyl, chloromethyl or hydroxymethyl group, at least one of Q and O' being hydrogen, Z is a phenyl, C 1-18 alkyl or (C 1-15 alkyl) phenyl group, X is oxygen or sulphur and n is 1-70. The coating compositions contain, in addition to the copolymer and amino formaldehyde resin, a strong acid catalyst, e.g. H 3 PO 4 or p.-toluene sulphonic acid, a solvent, e.g. an aromatic hydrocarbon, an aliphatic alcohol, a glycol ether, glycol ether ester or a mixture thereof, a levelling agent, e.g. a polysiloxanepolyoxyalkylene block copolymer, and, optionally, a pigment. Curing is effected by heating to coated substrate to 100‹-300‹C for 15-60 minutes. Example VIII describes coating tin plate with a composition based on copolymers of hydroxypropyl methoxyethyl maleate or hydroxypropyl phenoxypropyl maleate/styrene/methyl or butyl methacrylate crosslinked with hexamethoxylmethylmelamine.