Method of protecting substrates with light-stable varnish or lacquer

Abstract

Abstract Disclosed is a process for coating a substrate with a transparent, weather-resistant, light-stable exterior varnish or lacquer comprising blending a transparent coating resin free of drying types of unsaturation, and free of chlorine and bromine, and a minor amount of a compatible transparent, uncured, unoxidized, water-insoluble linear condensation resin of formaldehyde and a phenol having the formula: wherein R'' is a radical selected from the group consisting of alkyl, substituted alkyl, cycloalkyl, substituted cycloalkyl, aryl, and substituted aryl, and R and R'''' are radicals taken from said group or H, the methylene groups in the condensation resin being in the ortho, ortho'' position with respect to the hydroxy group, applying a thin coating of the transparent composition to a substrate, and exposing said coating to conditions, for instance outdoor exposure and/or an oxidation catalyst such as the metallic driers commonly used with unsaturated drying oils, such that oxidation of the phenolaldehyde condensate is achieved to an extent that at least some of the ortho, ortho'' -CH2- groups connected to phenol rings are converted to groups, whereby the oxidized phenol-aldehyde condensate protects the coating resin and substrate from oxidation or degradation induced by actinic light or other means, the amount of condensation resin being from 5 percent to 35 percent, preferably 10 to 30 percent, based on the combined weights of the resins. The phenol-aldehyde resin may be oxidized prior to being introduced into a coating resin, or it may be oxidized while mixed with the coating resin when it is in liquid form, as an aqueous dispersion, organic solvent solution, or non-aqueous dispersion of the polymer.

Inventors

• 👤 Andrew Mercurio
• 👤 Peter R Sperry

Bibliographic Details