Inhibition of filiform corrosion of an aluminium@ auto wheel - by application of powder clear coat compsn. contg. thermoset resin and UV additive

摘要

Inhibition of filiform corrosion of an aluminium auto road wheel comprises: (a) spray applying to a bare surface a powder clearcoat compsn. (A); and (b) thermally curing the compsn. to give an adhered, protective coating on the surface. Compsn. (A) consists of: (i) a thermoset resin; and (ii) a UV additive contg. a UV absorber and a light stabilizer compatible with (i). Also claimed is the inhibition of filiform corrosion of the surface of a 356A aluminium alloy auto road wheel by exposure to a chromate salt soln. for 90 secs. at at least 84 deg.F, and drying at 140 deg.F, the surface is electrostatically spray coated with a coating compsn. contg. 50-150 pts. wt. of (i), 0.2-15 opts. wt. of (ii), and minor amts. of flow control additive and autioxidant. The compsn. is cured at 275-425 deg.F. (ii) contains 1-10 pts. wt. of a benzotriazole UV absorber and .1-5 pts. wt. of a hindered amine light stabiliser. (i) consists of a glycidyl functional methacrylate copolymer resin and dodecanedioic acid.