CURABLE POWDER COATING COMPOSITION COMPRISING A MIXTURE OF AN ALKOXYLATED POLYAMINE-ALDEHYDE RESIN AND A POLYESTER RESIN

摘要

1305208 Polyester/aminoplast compositions UNILEVER NV 23 Jan 1970 [28 Jan 1969] 3398/70 Heading C3R A curable powder coating composition having a good powder stability comprises 3-15% by weight of an alkoxylated polyamine-aldehyde resin, e.g. hexamethoxy-methylmelamine and 85-97% by weight of a polyester resin having an acid number below 20 and a softening point of 60-130‹ C. in which the polyester is derived from a carbocyclic dicarboxylic acid and (a) 0-100 mole per cent (based on total alcohol component) of where R 1 and R 2 are alkylene groups of 2-4 carbon atoms, R 3 is an alkylidene group of 3-4 carbon atoms or a cycloalkylidene group of 6 carbon atoms, a carbonyl or sulphone group, x and y are each 1 or more with x + y being not greater than 6 and R 4 and R 5 are H atoms or alkyl radicals of 1-6 carbon atoms; (b) 0-40 mole per cent of a glycidyl ester having the general formula in which R is a straight or branched chain, saturated or unsaturated hydrocarbyl group having from 4 to 20 carbon atoms, or a substituted or unsubstituted benzene nucleus; (c) 0-100 mole per cent of at least one dihydric, aliphatic alcohol, and (d) 0-10 mole per cent of at least one aliphatic polyhydric alcohol, the sum of the alcohol components (a), (b), (c) and (d) being 100 mole per cent. The curable coating composition is applied to a substrate by a powder coating process and the coated substrate is then heated to a temperature of from 120‹ to 250‹ C. for 10 to 60 minutes to cure the composition. The following polyester components are specifically mentioned in the examples: terephthalic acid, isophthalic acid, HET-acid, the diether of ethylene or propylene glycol and bisphenol A, the glycidyl ester of branched chain monocarboxylic acids having about 9 to 11 carbon atoms, ethylene glycol, neopentyl glycol, hexanediol-1,6 and trimethylpropane. The compositions may inelude small amounts of other resins or other organic compounds to improve the film-forming properties, also grinding aids, curing agents or accelerators, flow control agents, surface-active agents, heat-stable organic or inorganic pigments, inert fibres, inhibitors, abrasives and plasticizers.