GB726694A - Synthetic resinous compositions for coating metals - Google Patents

Abstract

A coating composition for metals comprises (1) 20 to 82 per cent (by weight) of a resin product comprising the reaction product of (a) 25 to 85 per cent (by weight) of one or more silanes of the formula RnSiX4-n, wherein R is an alkyl radical of less than 5 carbon atoms or a monocyclic aryl radical, n has an average value of 1 to 2, X is a halogen atom or alkoxy radical containing less than 5 carbon atoms, and/or one or more hydrolysates of the silanes, (b) 2.5 to 49 per cent of glycerine, and (c) 5.2 to 62 per cent of a dicarboxylic acid (including the anhydride, alkyl ester and acid chloride thereof), and (2) 18 to 80 per cent of an alkylated melamine-formaldehyde and/or an alkylated urea-formaldehyde resin. Methods of making the silico-alkyd resin component (1) are described in Specifications 663,599, 689,662, 689,663, 691,013, 691,014 and 691,015. The silico-alkyd resin may be modified by saturated or unsaturated fatty acids containing 8 to 20 carbon atoms, e.g. stearic, 2-ethylhexoic, tung oil, castor oil, linseed oil and oiticica oil acids and mixtures thereof, as described in Specification 722,484. Mixing of the component resins is preferably effected in solution in solvents such as xylene, toluene, ketones, ethers, butanol or mixtures thereof. Pigments and drying catalysts such as cobalt or zinc naphthenates or octoates may be added. The compositions may be applied to metal surfaces by brushing, dipping or spraying and thereafter baked at 150 DEG to 350 DEG F. Examples are given.