GB988983A - Stoving lacquers - Google Patents

Abstract

A stoving lacquer contains water and, in dissolved form, at least one aqueous ammonia soluble polymeric substance which has the structure of a copolymer of:-(a) 2 to 30% by weight of at least one ethelenically unsaturated monomer having a carbonamide or carbonimide group whose nitrogen atom beans an oxaalkoxymethyl group, (b) 1 to 2o% by weight of at least one other ethelenically unsaturated monomer having a carboxyl group or a salt thereof, and (c) 50 to 97% by weight of at least one other ethelenically unsaturated monomer, the sum of the percentages under (a), (b) and (c) being 100. A long list of suitable types of oxaalkoxymethyl amides and imides (a) is given and N-[(3-oxabutoxy)-methyl]-acrylamide is exemplified. In the examples monomer (b) is acrylic acid or methacrylic acid, present as the N, N-dimethyl-N(2-hydroxy-ethyl)-amine salt; a number of others are specified. A long list including many different types of monomer (c) is given; those exemplified are: acrylonitrile, styrene, isobutyl acrylate, 2-ethylhexylacrylate, and 4-hydroxybutyl acrylate. Copolymerization catalysts employed are azodiisobutyronitrile and cumene hydroperoxide. Tertiary-dodecyl-mercaptan is also added in some of the examples. The copolymer is also made using, in place of monomer (a) either methacrylamide or monoacryloylurea and after polymerization converting the copolymer into the corresponding N-(oxaalkoxymethyl) derivative by treating with formaldehyde and ethanediol monomethyl ether and, in some examples, with maleic anhydride also. The lacquer may also contain other conventional stoving lacquer components such as other aqueous ammonia soluble polymers, aqueous dispersions of polymers, epoxy compounds, aminoplasts and their precondensates, phenoplasts and their precondensates, and alkyd resins; conventional additives such as soluble dyes, pigments and hexavalent chromium compounds; and, in addition to water, organic water-miscible solvents such as alcohols, esters, ethers and ketones. A number of these components and additives are specified of which titanium dioxide and the reaction product of 2,2 - bis - (p - hydroxyphenyl) - propane and 1-chloro-2,3-epoxypropane are exemplified. The pH of the lacquer may be adjusted with inorganic or organic bases conventional in aqueous storing lacquers. The lacquer may be applied to metals, wood, plastics or ceramics.ALSO:A stoving lacquer contains water and, in dissolved form, at least one aqueous ammonia soluble polymeric substance which has the structure of a copolymer of (a) 2-30% by weight of at least one ethylenically unsaturated monomer having a carbonamide or carbonimide group whose nitrogen atom bears an oxaalkoxymethyl group, (b) 1-20% by weight of at least one other ethylenically unsaturated monomer having a carboxyl group or a salt thereof, and (c) 50-97% by weight of at least one other ethylenically unsaturated monomer, the sum of the percentages under (a), (b) and (c) being 100. A long list of suitable types of oxaalkoxymethyl amides and imides (a) is given and N-[(3-oxabutoxy)-methyl]-acrylamide is exemplified. In the examples monomer (b) is acrylic acid or methacrylic acid, present as the N,N-dimethyl-N(2-hydroxyethyl)-amine salt; a number of others are specified. A long list including many different types of monomer (c) is given; those exemplified are: acrylonitrile, styrene, isobutyl acrylate, 2-ethylhexylacrylate, and 4-hydroxybutyl acrylate. Copolymerization catalysts employed are azodiisobutyronitrile and cumene hydroperoxide. Tertiary-dodecyl-mercaptan is also added in some of the examples. The copolymer is also made using, in place of monomer (a) either methacrylamide or monoacryloylurea and after polymerization converting the copolymer into the corresponding N-(oxaalkoxymethyl) derivative by treating with formaldehyde and ethanediol monomethyl ether and, in some examples, with maleic anhydride also. The lacquer may also contain other conventional stoving lacquer components such as other aqueous ammonia soluble polymers, aqueous dispersions of polymers, epoxy compounds, aminoplasts and their precondensates, phenoplasts and their precondensates, and alkyd resins: conventional additives such as soluble dyes, pigments and hexavalent chromium compounds; and, in addition to water, organic water-miscible solvents such as alcohols, esters, ethers and ketones. A number of these components and additives are specified of which titanium dioxide and the reaction product of 2,2-bis-(p-hydroxyphenyl)-propane and 1-chloro-2,3-epoxypropane are exemplified. The pH of the lacquer may be adjusted with inorganic or organic bases conventional in aqueous stoving lacquers. The lacquer may be applied to metals, e.g. aluminium, iron and magnesium, wood, plastics or ceramics. Articles which may be coated include vehicle bodies, ships, washing machines, refrigerators, boxes, cans and tubs.