GB1459274A - Coating compositions - Google Patents

Abstract

1459274 Coating compositions HOECHST AG 8 March 1974 [10 March 1973] 10590/74 Headings C3B C3P and C3R A water-dilutable coating composition is made by neutralizing with a base, to pH > 7, a solution in an organic solvent of a mixture or a precondensate of (A) a COOH-containing resin with acid number #40 and (B) an aminoplast containing C 1-4 alkylol groups, 30-70% of which are esterified with C 1-3 alcohol(s), the remainder being free alkylol groups; the total amount of (solvent + base used for neutralization) in the final composition being #35% wt. In (B), the ratio of the total number of alkylol groups (free + esterified) to the total number of C + N atoms in the aminoplastforming amine is from 2 : 3 to 4 : 3; and the ratio of N : C, by number of atoms, in this amine is from 2 : 1 to 1 : 1. Resin (A) may be an acrylic resin, an unsaturated polyester, and/or an epoxy resin ester. Aminoplast (B) may be derived from urea, guanamine, or melamine, and formaldehyde, acetaldehyde, propionaldehyde, and/or isobutyraldehyde. The etherifying alcohol may be methanol, ethanol and/or isopropanol. Wt. ratio of (A) : (B) may be from 10 : 1 to 1 : 10. The base may be ammonia or a secondary or tertiary amine, e.g. trimethylamine, triethylamine, tripropylamine, diisopropylamine, or morpholine. The final pH of the solution may be 8-9À5. In examples, the solvent is isopropanol. (A) and (B) may be mixed at room temperature. The mixture may, before step (2), be precondensed at 30-80‹ C. The composition may additionally contain water, a pigment and/or a wetting agent. An article may be coated by application of the composition directly to the surface of the article, followed by stoving at #160‹ C.