GB1055614A - Colour lakes - Google Patents

Abstract

A colour lake consists essentially of a basic dye and an alkali-soluble condensation product which is obtained by reacting in an acid aqueous medium (a) 2-5 mols. of an aromatic hydroxy compound, (b) 1-6 mols. of urea, alkylurea or alkylene urea or a methylol or methylol ether derivative thereof, (c) 1-6 mols. of an aromatic mononuclear carboxylic, sulphonic, aminocarboxylic, aminosulphonic or hydroxycarboxylic acid or an aliphatic dicarboxylic acid or an aryloxy fatty acid, and (d) 9-11 mols. of formaldehyde or a compound yielding formaldehyde, the formaldehyde preferably amounting to 38-50 mol. per cent of the total. Suitable compounds are (a) phenol, the cresols, 4-t-butylphenol, thymol, a - and b -naphthols. pyrocatechol (empyreumatic oils), partly methylated pyrocatechol, resorcinol, hydroquinone, 2- and 4-hydroxydiphenyl, 4,41-dihydroxy-diphenyl-methane, -propane and -sulphone, 4-hydroxydiphenylsulphone and phenylhydroxynaphthylsulphone, (b) urea, methylurea, N,N1-dimethylurea, ethyleneurea, propyleneurea, and acetylenediurea, and preferably methylol or dimethylolureas and alkyl ethers thereof, when (d) is correspondingly reduced, (c) benzoic acid, benzenesulphonic acid, p-toluenesulphonic acid, anthranilic acid, sulphanilic acid, 2-hydroxy-4-aminobenzoic acid, salicylic acid, gallic acid, malonic acid, glutaric acid and phenoxyacetic acid, (d) free formaldehyde, formalin, 1,3,5-trioxane, paraformaldehyde and hexamethylene tetramine. The condensation is preferably conducted between 30 DEG C. and the reflux point. The products may be washed with hot water and dried in vacuo, or on a roller or in a spray dryer. They are soluble, e.g. in methanol, ethanol, ethylene glycol, and acetone, and may be used as laking agents for basic dyes, e.g. auramine, rhodamine, Victoria Blue, methyl violet and crystal violet dyes and malachite green, to be used in carbon paper waxes, lithographic compositions and ballpoint pen inks. In examples, hydroxy diphenylsulphone, phenol or 4,41-dihydroxy-diphenylsulphone, plus thymol, resorcinol, hydroquinone, 2 - hydroxydiphenyl or p - t - butyl-phenol, and salicylic acid, and dimethylolurea or a urea-formaldehyde mixture are added to concentrated HCl and refluxed. In other examples, benzoic, anthranilic, sulphanilic or salicylic acid and dimethylolurea or its methyl ether or dimethylol ethyleneurea are added separately to the reaction product of 4,41-dihydroxydiphenylsulphone or p-t-butylphenol with formalin in hydrochloric acid solution. A flexographic printing ink containing 30 parts of a styrene/diethyl maleate copolymer, 90 of ethanol, 10 of ethylene glycol, 7 of rhodamine B and 14 of a hydroxydiphenylsulphone/thymol/ salicylic acid/dimethylolurea condensate is described.