GB916497A - Improvements in or relating to multicolour coating composition and method for preparation thereof - Google Patents

Abstract

A multicolour oil-in-water emulsion coating composition, which upon a single pass of a spray gun provides a coloured base interspersed with a plurality of discrete particles of different colours from that of the base, comprises an aqueous solution of 0-20% of a protective colloid as the continuous phase, a disperse phase comprising microscopically suspended pigment particles and a paint latex emulsion polymer, of ethylenically unsaturated monomers and macroscopically suspended therein one or more pigmented viscid liquid hydrophobic organic varnish coating compositions, the varnish vehicle of which is characterized by one hydrophilic number requirement of less than 59. The protective colloid is preferably a water soluble alkyl cellulose ether, but may be any of the commonly used protective colloids including the water dispersible polymers such as sodium or ammonium polyacrylate. The preferred paint latex emulsion polymer is a copolymer of an aromatic monovinyl hydrocarbon, e.g. styrene or vinyltoluene (up to 67 mol. per cent by weight) and a conjugated diene, e.g. butadiene (up to 60 mol. per cent by weight); a terpolymer may be used in which the third component is a lower alkyl acrylate or a vinylidene monomer. Other paint latex emulsion polymers specified are polyacrylonitrile, polyacrylates, polybutadiene, polyvinyl acetate or a partially hydrolysed polyvinyl acetate, and a copolymer of vinyl acetate and dibutyl maleate. In Example I, an orange hydrophobic varnish coating composition is prepared from a dehydrated castor oil fatty acids modified glycidyl ether of bis-phenol thinned with a high boiling naphtha, calcium carbonate-silica pigment, molybdate orange, diatomaceous earth, and lead cobalt and manganese driers; a blue hydrophobic coating composition is similarly prepared using phthalocyanine blue instead of molybdate orange; and these are stirred slowly into a mixture of water, titanium dioxide, black iron oxide, calcium carbonate-silica pigment, methyl cellulose, sulphonated tallow (anti-foam agent), sodium orthophenyl phenate, a 45% solids emulsion copolymer of styrene and butadiene, and a cobalt drier to give on spraying a grey base coat with a superimposed or interspersed splatter coat of visibly large orange and blue particles. Other hydrophobic varnishes which can be used to produce the macroscopic particles are prepared from mixtures of (1) tall oil, black oil, Manhadden oil, pentaerythritol, litharge, phthalic anhydride and mineral spirits; (2) soyabean oil, black oil, glycerine, pentaerythritol, litharge, phthalic anhydride and mineral spirits; (3) rosin, gilsonite, blown Texas asphaltum and mineral spirits; (4) dehydrated castor oil fatty acids, a glycidyl ether resin having epoxide equivalent 870-1025, triphenyl phosphite and xylol; (5) linseed oil, anthraquinone, white rosin, fumaric acid and pentaerythritol and (6) China wood oil, heat bodied linseed oil, cumarone indene resin, high flash naphtha and mineral spirits. Specification 916,496 is referred to.