GB517476A - Preparation of improved colouring matters - Google Patents

Abstract

517,476. Pigments. MOILLIET, J. L., and IMPERIAL CHEMICAL INDUSTRIES, Ltd. July 29, 1938, No. 22540. [Classes 1 (ii) and 95] [Also in Group IV] Dry powders are manufactured from aqueous pastes of water-insoluble colouring matters, e.g., artificial inorganic pigments such as the prussian blues and the chrome yellows, the barium or other salts of lake dyestuffs such a 6-sulpho-4-chloro-3-tolueneazo-#-naphthol, or synthetic organic pigments such as o-nitro-ptolueneazo-#-naphthol and p-nitrobenzeneazo- #-naphthol, by bringing into admixture with the paste a cationic surface active compound (i.e., a compound containing, attached to the positive radicle thereof, an aliphatic hydrocarbon radicle of at least 8 carbon atoms), and a volatile organic liquid, boiling between 60‹ and 250‹C., substantially immiscible with water and not a solvent for the colouring matter, and drying the resulting composite paste, advantageously at 60‹-90‹C. Suitable surface active compounds are the water-soluble salts, e.g., sulphates, chlorides or bromides, of aliphatic quaternary ammonium or phosphonium or ternary sulphonium compounds with an aliphatic hydrocarbon radicle of at least 8 carbon atoms attached to the nitrogen, phosphorus or sulphur atom, betaines, e.g., octadecylbetaine, and salts of inorganic acids with primary, secondary or tertiary amines having an aliphatic hydrocarbon radicle of at least 8 carbon atoms. The surface active agent and organic liquid may be added at any time previous to the drying of the aqueous paste, e.g., they may be present in the liquid when the colouring matter is precipitated or may be added to the slurry before filtration or to the filter-press cake. They are advantageously added as an aqueous emulsion prepared by emulsifying the organic liquid with the aid of the cationic surface active agent as emulsifying agent. Alternatively, the organic liquid may be emulsified with a non-cationic surface active agent, the cationic surface active agent being added separately. In examples: (1) a slurry of prussian blue is mixed with an aqueous solution of cetyltrimethylammonium bromide and with toluene (or with an aqueous emulsion of toluene and the said surface active agent), and the mixture is filtered, washed and dried; (2) an aqueous press cake of prussian blue is mixed with cetyltrimethylammonium bromide and toluene and then dried and pulverized; (3) an aqueous suspension of the barium salt of 6-sulpho-4- chloro-3-toluneazo-#-naphthol is mixed with an aqueous solution of cetyltrimethylammonium bromide and with an aqueous emulsion of toluene prepared with the aid of a highly sulphonated oleic acid, and the mixture is filtered, washed and dried; (4) an aqueous paste of prussian blue is mixed with cetyl-pdimethylaminobenzoate methosulphate and amyl acetate and then dried; there may alternatively be used as the surface active agent dicetyldimethylammonium bromide, cetylpyridinium bromide or cetoxymethylpyridinium oxalate, and as the organic liquid trichlorethylene, toluene or dimethylaniline ; (5) an aqueous paste of Monolite Red R is mixed with an aqueous solution of dicetyldimethylammonium bromide and with trichlorethylene and then dried; (6) an aqueous paste of the barium salt of Lake Red C is mixed with an aqueous solution of dodecyldimethylsulphonium methylsulphate and with toluene and then dried. Other organic liquids specified are tetrachlorethylene, industrial white spirit, fenchone and fusel oil. Specification 499,334, is referred to.