High-solid content hydroxy-polyester coating compsns - contg polyamides, derived from phenol hydroxy-alkyl ethers, and of low viscosity

摘要

New high-solid content hydroxy-polyester systems (with low solvent concn.), with low viscosity are reaction prods. of (a) hydroxy-cpds. of formula: H(OR)m-O-PHI-A-PHI-O-(RO)nH, (in which PHI is a p-phenylene gp.; A is a direct C-C bond between the 2 rings, -CO-, -S-, -SO2-, -O-, -CH2- or 3-4C 2-alkylidene; m >=1; n >=1; m+n =20; R is a 2-4C alkylene radical or, if m = 1, n = 1 and m+n =3, can also be styrene oxide adduct), and (b) aromatic and/or cycloaliphatic dicarboxylic acids or their anhydrides or methyl esters. These systems can be cured with aminoplastics, giving coatings with high adhesion, elasticity, flexibility profiling capacity, hardness and impact strength. They can also be combined with other cross-linking agents, e.g. isocyanates and isocyanate adducts, or used in combination with nitrocellulose etc. Reaction of silanes with reactive OH or OMe gps. with (some of) the OH gps. of the polyester before use for the prodn. of coatings, opt. in combination with aminoplastics, improves the weathering resistance and gloss retention.