GB545394A - Improvements relating to the production of dyestuffs on textile fibres - Google Patents

Abstract

545,394. Dyeing textiles. CALICO PRINTERS' ASSOCIATION, Ltd., and LANTZ, L. A. Feb. 7, 1941, No. 1678. [Classes 2 (iii) and 15 (ii)] Aniline-black and like dyeing; printing. Brown shades are produced on textile fibres by oxidation thereon of a condensation product of m-phenylenediamine with formaldehyde in an acid medium. Preferably to 1 mol: of formaldehyde is condensed with 1 mol. of the diamine. Oxidationcatalysts such as compounds of vanadium, copper or cerium, may be used. Printing may be effected with a paste made by adding formaldehyde and a thickening agent to an.acidified aqueous solution of the diamine, an oxidizing agent being incorporated in the paste or used for an after-treatment of the printed fabric. Alternatively the formaldehyde may be caused to react with the diamine in an acid medium, whereupon the condensation product is precipitated by addition of alkali, filtered off, washed, dried, re-dissolved in acid and mixed with the thickening agent. Padding or impregnating liquors are obtainable by replacing the thickening wholly or in part by water. The brown shades may be modified by an after-treatment with a solution of a diazonium salt or by diazotization and coupling. with a component such as #-naphthol. In examples, (1) aqueous formaldehyde is added to an aqueous solution containing m-phenylenediamine and lactic acid and the solution is allowed to stand for 15 minutes, whereupon sodium chlorate and ammonium vanadate solutions and gum tragacanth thickening are added and the resulting paste is printed on cotton fabric, which is then dried, steamed, washed and soaped to obtain a nigger brown print ; (2) aqueous formaldehyde is added to an aqueous solution containing m-phenylenediamine and acetic acid and the solution is allowed to stand for 15 minutes, whereupon carob bean thickening is added and the resulting paste is printed on cotton fabric, which is then dried, passed through a cold aqueous solution containing sodium bichromate, copper sulphate and sulphuric acid, washed and soaped to obtain a reddish dark brown print ; (3) a solution obtained as in (1) without adding the thickening is diluted with water and used to impregnate a cotton fabric, which is then dried, printed with a resist preparation comprising an aqueous paste containing sodium formaldehydesulphoxylate, potassium sulphite, sodium acetate and gum tragacanth thickening, dried, steamed, washed and soaped to obtain a white pattern on a nigger brown ground ; (4) a print obtained as in (1) is developed with diazotized p-nitraniline, rinsed, soaped and dried to obtain a very dark chocolate brown print; (5) a print obtained as in (1) is diazotized on the fibre and developed with g-naphthol to obtain a rich mahogany brown print.