GB999061A - Coating compositions and methods - Google Patents

Abstract

A coating composition comprises an emulsion containing essentially an aqueous resin coating material and a resin dispersion, said aqueous resin coating material constituting the continuous phase and said resin dispersion constituting the discontinuous phase and being distributed as globules substantially homogeneously throughout said continuous phase. The aqueous resin coating materials may be the same or a different colour from the resin dispersion. An aqueous thickneing agent may be present, the preferred ones being methyl or hydroxymethyl cellulose and magnesium montmorillonite. Little or no volatile solvents are employed in the aqueous resin coating materials and examples of aqueous resin coating materials are: (A) melamine-acrylic emulsion, a phthalic alkyd resin, titanium dioxide, dimethylethanolamine, butyl "Cellosolve" (Registered Trade Mark), and tributyl phosphate; (B) phthalic-alkyd resin, water, titanium dioxide, tributyl phosphate, dimethylethanolamine and polyvinyl chloride latex; (C) water-soluble polyester resin, titanium dioxide, water and mineral spirits; and (D) melamine-acrylic resin, carbon black, mineral spirits and water. The non-aqueous dispersant for the resin dispersion is preferably comprised wholly of a plasticizer or a mixture of plasticizers although organosols may be used as a major portion of the dispersant. Examples of resin dispersions are: (A) vinyl chloride polymer, di-isodecyl phthalate, barium-cadmium organic stabilizer and lamp black; (B) vinyl chloride polymer, vinyl chloride-vinylidene chloride copolymer, di-isodecyl phthalate, secondary plasticizer, barium-cadmium organic stabilizer and pigment; (C) vinyl chloride polymer, di-isodecyl phthalate, dibutyl tin oxide paste in plasticizer, phthalocyanine blue pigment and titanium dioxide; (D) vinyl chloride polymer, di-isodecyl phthalate, xylol, thinner, barium-cadmium organic complex stabilizer and lampblack paste and (E) vinyl chloride polymer, trioctyl phosphate, dioctyl phthalate, calcium acetoacetate stabilizer, mineral spirits, di-isobutyl ketone and "Araldite" (Registered Trade Mark) stabilizer.ALSO:Metal panels, e.g. steel, copper, aluminium and brass; plastics, e.g. moulded phenolic plastic parts; glass; paper and fabrics such as cotton sailcloth may be coated with an emulsion containing essentially an aqueous resin coating material and a resin dispersion, said aqueous resin coating material constituting the continuous phase and said resin dispersion constituting the discontinuous phase and being distributed as globules substantially homogeneously throughout the continuous phase. The aqueous resin coating material may be an emulsion or solution of a synthetic resin in water, e.g. polyacrylic emulsions, polyester resins, polyvinyl chloride latices and butadiene-styrene copolymer emulsions may be used. The resin dispersion is a dispersion of resin particles in a non-aqueous liquid which may consist solely of plasticizers or may also contain volatile thinners. Stabilizers, pigments and fillers may also be added. A multi-coloured coating composition may be formed when the resin dispersion is of a colour different from the aqueous resin coating material. The resins used in the resin dispersion are polyvinyl chloride resins, either with or without minor proportions of copolymerized vinylidene chloride, vinyl maleate, vinyl acetate and alkyl acrylates and the plasticizers used to produce the dispersion are preferably various phthalates, adipates and trioctyl phosphate. Secondary plasticizers such as high boiling aromatic and aliphatic hydrocarbons, substituted hydrocarbons, fatty acid esters and polymeric materials may also be added. Aqueous thickening agents such as methyl and hydroxymethyl cellulose and magnesium montmorillonite may be added to the coating composition. The coating composition may be applied to the surface to be coated by spraying, dipping, roller coating or spread coating preferably to produce a coating 0,7-3 mils in thickness. After application the coating is dried by conventional means.