GB936911A - New pigment compositions - Google Patents

Abstract

A solid pigment composition for the pigmentation of non aqueous media, is prepared by flocculating a mixture of an aqueous pigment dispersion and an aqueous latex of solid synthetic polymer (i.e. does not include elastomers or waxes) which is soluble in said non aqueous medium to the extent of at least 2% by weight and preferably at least 5% by weight, said latex being obtained by emulsion polymerization of a monomer or a mixture of monomers and the diameter of the polymer particles in latex being between 0,01 and 0,5 micron, separating the flocculated mixture from the aqueous phase and drying it. Pigments may be of the inorganic type, e.g. titanium dioxide, zinc oxide, cadmium sulphide, carbon black, iron oxides, ultramarine, cobalt blue, Prussian blue, lead chromate and chromium oxide or of the organic type, e.g. azo, vat dye, triphendioxazine, phthalocyanine, e.g. copper phthalocyanine, its nuclear chlorinated derivatives and copper tetra- and octaphenyl phthalocyanine, quinacridone, e.g. linear quinacridone and various other pigments. Preferred latices are prepared from vinyl alkylbenzenes, alkyl methacrylates and dialkyl fumarates, preferably in the presence of a chain transfer agent, e.g. alkyl mercaptan (t-dodecyl- and t-amylmercaptans). The flocculating step is carried out in the presence of an electrolyte such as a water soluble acid or salt other than an alkali metal salt, e.g. HCl and H2SO4. The flocculated mixture may be heated and cooled before being separated. In the examples an aqueous suspension of the pigment is ball-milled to give a dispersion to which is added a latex of a synthetic polymer and then this mixture is mixed with a flocculating agent. The flocculated product is filtered, washed free from acid and dried. The pigments specified are copper phthalocyanine, scarlet pigment, molybdated lead chromate, lead chromate, Brunswick green, Prussian blue, carbon black, yellow and red azo pigments, rubine and pink toner lakes, iron complex of a -nitroso-b -naphthol, copper hexadecachlorophthalocyanine, copper tetrabromododecachlorophthalocyanine, 6:61-dichloro-4:41-dimethylthiondigo, flavanthrone, dibromoanthrone, indanthrone and linear quinacridone. The synthetic polymers mixed with these pigments are prepared from commercial vinyltoluene and n-butyl methacrylate; vinyltoluene and n- or iso-butyl methacrylate; isobutyl methacrylate; vinyltoluene; or commercial vinyltoluene and di-n-butylfumarate. The pigment compositions are readily dispersible in alkyd resins, e.g. linseed oil modified alkyd resin and 69% oil length linseed pentaerythritol phthalate alkyd resin, cellulose acetate (which may be molten), cellulose nitrate, polythene, polypropylene, plasticised polyvinyl chloride, lithographic varnish, waxes, oils, e.g. linseed oil, and organic solvents.ALSO:A solid pigment composition for the pigmentation of non aqueous media, is prepared by flocculating a mixture of an aqueous pigment dispersion and an aqueous latex of solid synthetic polymer (i.e. does not include elastomers or waxes) which is soluble in said non aqueous medium to the extent of at least 2% by weight and preferably at least 5% by weight, said latex being p obtained by emulsion polymerization of a monomer or a mixture of monomers and the diameter of the polymer particles in latex being between 0,01 and 0,5 micron, separating the flocculated mixture from the aqueous phase and drying it. Pigments may be of the inorganic type, e.g. titanium dioxide, zinc oxide, cadmium sulphide, carbon black, iron oxides, ultramarine, cobalt blue, Prussian blue, lead chromate and chromium oxide or of the organic type, e.g. azo, vat dye, triphendioxazine, phthalocyanine, e.g. copper phthalocyanine, its nuclear chlorinated derivatives and copper tetra- and octa-phenyl phthalocyanine, quinacridone, e.g. linear quinacridone and various other pigments. Preferred latices are prepared from vinyl alkyl benzenes, alkyl methacrylates and dialkyl fumarates, preferably in the presence of a chain transfer agent, e.g. alkyl mercaptan (t-dodecyl and t-amyl-mercaptans). The flocculating step is carried out in the presence of an electrolyte such as a water-soluble acid or salt other than an alkali metal salt, e.g. HCl and H2SO4. The flocculated mixture may be heated and cooled before being separated. In the examples an aqueous suspension of the pigment is ball-milled to give a dispersion to which is added a latex of a synthetic polymer and then this mixture is mixed with a flocculating agent. The flocculated product is filtered, washed free from acid and dried. The pigments specified are copper phthalocyanine, scarlet pigment, molybdated lead chromate, lead chromate, Brunswick green, Prussian blue, carbon black, yellow and red azo pigments, rubine and pink toner lakes, iron complex of a -nitroso-b -naphthol, copper hexadecachlorophthalocyanine, copper tetrabromo dodecachlorophthalocyanine, 6:61-dichloro-4:41-dimethyl thioindigo, flavanthrone, dibromoanthrone, indanthrone and linear quinacridone. The synthetic polymers mixed with these pigments are prepared from commercial vinyltoluene and n-butyl methacrylate; vinyltoluene and n- or iso-butyl methacrylate; isobutyl methacrylate; vinyltoluene; or commercial vinyltoluene and di-n-butylfumarate. The pigment compositions are readily dispersible in alkyd resins, e.g. linseed oil modified alkyd resin and 69% oil length linseed pentaerythritol phthalate alkyd resin, cellulose acetate (which may be molten), cellulose nitrate, polythene, polypropylene, plasticized polyvinyl chloride, lithographic varnish, waxes, oils, e.g. linseed oil, and organic solvents.