Patent GB-882199-A (GB)
Title: Organic liquid coating composition and a method for the preparation thereof
Filed: 1957-12-12
Abstract: A liquid coating composition comprises discrete particles of a liquid coating medium, containing pigment and an organic liquid, dispersed in an organic liquid dispersing medium containing a soluble suspension stabilizer, most of the particles of the coating medium being larger than 50 microns, and the organic liquid of the coating medium being insoluble in the dispersing medium.  The organic liquid of the coating medium may include an aliphatic hydrocarbon, especially petroleum naphtha, and may comprise a drying oil or a curable liquid resin.  Preferably, the coating medium comprises a film-forming resin, especially an alkyd resin, in solution in a liquid aliphatic hydrocarbon, and may also contain a puffing agent selected from the group consisting of aluminium soaps, bentonite gels, caster oil gels and trivalent metal alkoxides.  Some of the discrete particles of the coating medium may be of a different colour from that of the remainder of the particles.  The dispersing medium preferably comprises nitromethane and the preferred suspension stabilizer is polyisobutyl methacrylate, but acrylic or vinyl resins, or cellulose esters, may also be used.  Other, less preferred, systems utilize petroleum naphtha as the coating medium or inner phase solvent, dimethyl sulphoxide, carbon disulphide, pyrrole, dimethyl formamide, methanol or enthanol as the outer phase. Specified coating media include cellulose acetate butyrate, polyisobutyl methacrylate, butadiene-styrene copolymer, polybutadiene, natural rubber, alkyd resins and linseed oil. Specified pigments include titanium dioxide, iron red, and chrome yellow.  The composition may be made by adding the coating medium to the dispersing medium and agitating the mixture to form a dispersion, agitation being stopped before emulsion size particles are formed, so that most of the coating medium particles are larger than 50 microns, the amount of suspension stabilizer in the dispersing medium being sufficient to prevent appreciable coalescence of the particles.  A second coating medium which may be of a different colour from the first, may be similarly dispersed in the dispersing medium.ALSO:A liquid coating composition comprises discrete particles of a liquid coating medium, containing pigment and an organic liquid, dispersed in an organic liquid dispersing medium containing a soluble suspension stabilizer, most of the particles of the coating medium being larger than 50 microns, and the organic liquid of the coating medium being insoluble in the dispersing medium.  The organic liquid of the coating medium may include an aliphatic hydrocarbon, especially petroleum naphtha, and may comprise a drying oil or a curable liquid resin.  Preferably, the coating medium comprises a film-forming resin, especially an alkyd resin, in solution in a liquid aliphatic hydrocarbon, and may also contain a puffing agent selected from the group consisting of aluminium soaps, bentonite gels, caster oil gels and trivalent metal alkoxides.  Some of the discrete particles of the coating medium may be of a different colour from that of the remainder of the particles.  The dispersing medium preferably comprises nitromethane and the preferred suspension stabilizer is polyisobutyl methacrylate, but acrylic or vinyl resins, or cellulose esters, may also be used.  Other, less preferred, systems utilize petroleum naphtha as the coating medium or inner phase solvent and dimethyl sulphoxide, carbon disulphide, pyrrole, dimethyl formamide, methanol or ethanol as the outer phase. Specified coating media include cellulose acetate butyrate, polyisobutyl methacrylate, butadiene-styrene copolymer, polybutadiene, natural rubber, alkyd resins and linseed oil. Specified pigments include titanium dioxide, iron red, and chrome yellow.  The composition may be made by adding the coating medium to the dispersing medium and agitating the mixture to form a dispersion, agitation being stopped before emulsion size particles are formed, so that most of the coating medium particles are larger than 50 microns, the amount of suspension stabilizer in the dispersing medium being sufficient to prevent appreciable coalescence of the particles.  A second coating medium, which may be of a different colour from the first, may be similarly dispersed in the dispersing medium.