GB744524A - Improved anti-corrosive paints, of the type having a natural or synthetic acidic oil or resin base, for oxidisable metals and their oxidisable alloys and methods or processes of making same - Google Patents

Abstract

An anti-corrosive paint comprises a natural or synthetic acidic oil or acidic resin base, having at least one stable inorganic water-soluble nitrite substantially evenly dispersed therethrough, the acidic base having been neutralized to provide a substantially inert carrier for the nitrite. The nitrile may be readily water-soluble, e.g. sodium nitrite, or only slightly so, e.g. silver nitrite, potassium cobaltinitrite, certain basic nitrites and nitrite complexes of copper and chromium. High-boiling solvents, e.g. those having the formul HO.CH2.CH2.OC2H5 and HO.CH2.CH2.OCH2.CH2.O.C2H5 may be used to assist the blending of nitrite solutions and resins, or the nitrite may be carried on a powder such as diatomite, or other form of silica, wood flour, plaster of paris, magnesium oxide, talc, titanium dioxide or the like. Where emulsions are formed, these may be stabilized by the incorporation of bentonite gel, methyl cellulose gel, alkaline casein, mucilage or the like or by homogenization. In examples: (1) long oil alkyd resin is mixed with raw linseed oil, and to the mixture is added an aqueous solution of sodium nitrite and potassium hydroxide, when an emulsion results, which may be pigmented with pigments pasted with water; (2) a stoving enamel is made by mixing a long oil alkyd resin first with ethylene diamine, then with silver nitrite titanium dioxide and xylol.ALSO:An anticorrosive paint comprises a natural or synthetic acidic oil or acidic resin base, having at least one stable inorganic water-soluble nitrite substantially evenly dispersed therethrough, the acidic base having been neutralized or rendered slightly alkaline to provide a substantially inert carrier for the nitrite. The nitrite may be readily water-soluble, e.g. sodium nitrite, or only slightly so, e.g. silver nitrite or potassium cobaltinitrite, certain basic nitrites and nitrite complexes of copper and chromium or a mixture of both kinds. Vehicles mentioned include drying oils such as linseed and tung oils, natural resins and synthetic resins such as methyl methacrylate and polyvinyl resins, and long-oil alkyd resins. Tung and linseed oils usually form emulsions on neutralization, to which aqueous nitrite solutions may be added; the emulsions may be stabilized by incorporation of bentonite gel, methyl cellulose gel, alkaline casein, mucilage or the like or by homogenization. High-boiling solvents e.g. those having the formul HO-CH2-CH2, OCrH5 and HO-CH2-CH2, OCH2CH2, OC2H5 may be used to assist the blending of nitrite solutions and resins. The nitrite may be present in the proportion of 0.1 per cent to 10 per cent or more of the weight of the finished product; it may be carried on a powder such as diatomite or other form of silica, plaster of Paris, wood flour, magnesium oxide, talc, titanium dioxide or the like. In Examples (1) long oil alkyd resin or long oil copal varnish is mixed with raw linseed oil, and to the mixture is added an aqueous solution of sodium nitrite and potassium hydroxide, when an emulsion results, which may be pigmented with pigments pasted with water; (2) a stoving enamel is made by mixing a long oil alkyd resin with ethylene diamine, silver nitrite, titanium dioxide and xylol.