GB1007588A - Aminoplast composition and production thereof - Google Patents

Abstract

Hardenable resins are produced by etherifying a solvent-soluble condensate of an aldehyde and a compound of the type <FORM:1007588/C3/1> <FORM:1007588/C3/2> or <FORM:1007588/C3/3> where R1, R2, R3, R4 are -H, -NH2, -CN, <FORM:1007588/C3/4> or alkyl radicals or R2 and R3 together are an alkylene radical, at least two of these radicals being -H, A is O, S or =NH, R5, R6 and R7 are -NH2, -H, OH, halogen, alkyl, aryl, aralkyl or alkaryl radicals or -NHR9, where R9 is -NH2 or alkyl, aryl, aralkyl or alkaryl, and R8 is -NH- or an alkylene radical, compounds (ii) and (iii) containing each at least 2 H atoms bound through nitrogen to a triazine ring carbon atom, with an a ,b -unsaturated carboxylic partial ester of a polyhydric alcohol, in the absence of substantial addition polymerization. This first-stage product may be further esterified with an alcohol, and/or copolymerized with one or more ethylenically unsaturated monomers to give a second-stage product. Suitable starting materials are:-aminoplast-forming compounds-urea, thiourea, guanidine, melamine and benzoguanamine; aldehydes-formaldehyde, acetaldehyde, benzaldehyde and furfuraldehyde; unsaturated partial esters-acrylic monoesters of glycols, alkyl hydroxyalkyl esters of butenedioic acids; alcohols-alkanols of 1-10 C atoms, benzyl alcohol, cycloalkanols, and lower alkoxyalkanols; unsaturated monomers-esters of a ,b -unsaturated acids, a ,b -unsaturated nitriles, and vinyl compounds. The molar ratio of unsaturated hydroxy ester to aminoplast-forming compound is preferably 0.1-1: 1. The aminoplast formation may take place simultaneously with or immediately prior to the etherification with the unsaturated hydroxy ester and the alcohol, if used. This stage is preferably performed in one stage in a single vessel. The product may be removed and stored in organic solvents, as below, if required, or treated immediately with the unsaturated monomers. The final second stage product should contain unsaturated hydroxy ester amounting to 1-30% of the addition polymer present, and preferably no unetherified hydroxy groups. When used in coating compositions the second-stage product may be dissolved in an amount up to 60% by weight in an organic solvent, e.g. alcohols, aromatic hydrocarbons, esters, ketones, ethers, nitroalkanes, acetonitrile, dimethylformamide and dimethyacetamide. Pigments, dyes and fillers may be added, e.g. TiO2 and carbon black. Preferred coating compositions comprise also 5-40% by weight of an epoxy resin, e.g. polyglycidyl ethers of bisphenols, and are dissolved in e.g. acetone, methyl ethyl ketone, xylene, toluene, and ether alcohols and esters thereof. In examples melamine-, urea- and benzoguanamine-formaldehyde resins are reacted with b -hydroxy-ethyl or hydroxy-propyl methacrylate and then with various acrylate/styrene mixtures containing styrene, methacrylic acid and/or methyl and/or butyl methacrylate and/or ethyl acrylate, using butanol, b -methoxyethanol and xylene as solvents, and coating compositions are described containing such resins together with TiO2 and a bisphenol A/epichlorhydrin resin in butanol, b -methoxyethanol and xylene solution.ALSO:Coating compositions comprise a hardenable resin obtained by etherifying a solvent-soluble aminoplast resin with an a ,b -unsaturated acid partial ester of a polyhydric alcohol. This resin may be further etherified by another alcohol, and is preferably copolymerized with at least one ethylenically unsaturated monomer (see Division C3). In preferred compositions this resin is blended with 5-40 weight per cent of an epoxy resin, and dissolved in e.g. acetone, methylethylketone, xylene, toluene or an ether alcohol or ester thereof. Pigments, dyes and filler may be added e.g. TiO2 or carbon black. In Example 18 resins from melamine-formaldehyde, b -hydroxyethyl methacrylate, and a mixture of methacrylic acid, methyl and butyl methacrylates, ethyl acrylate and styrene, are blended with a bisphenol A/epichlorhydrin resin and TiO2 in a butanol, b -methoxy-ethanol and xylene solvent, and applied to iron phosphate coated steel panels by spraying, then baked at 300 DEG F. to give an enamel coating.