Patent GB-400239-A (GB)
Title: Improvements in stripping dyed textiles
IPC: D06P5/13
Filed: 1932-03-19
Abstract: Dyeings produced by the combination on the fibre of arylamides of 2 : 3-oxynaphthoic acid with suitable diazo compounds are stripped by treatment of the dyed materials with a reducing liquor containing an amine, amine salt or quaternary ammonium salt carrying a radical which comprises a straight or branched carbon chain of not less than ten carbon atoms.  The liquor may be weakly alkaline, neutral or weakly acid, but is preferably acid when a quaternary ammonium salt is used or when dyed wool, silk or other animal fibre is treated. Vegetable fibre may also be treated with a liquor slightly acid, but may require a supplementary chlorine treatment to improve the effect. Animal fibres may require a supplementary peroxide treatment. Specified amines and amine salts are b -diethylaminoethyloleylamide or its acetate or hydrochloride, and heptadecylamine or its hydrochloride. Specified quaternary ammonium salts are octadecylpyridinium bromide, cetylpyridinium bromide (cf. Specification 379,396), cetylpyridinium chloride (cf. Specification 392,763), octadecyltrimethylammonium iodide, cetyltrimethylammonium bromide, cetyltriethylammonium bromide, cetyltrimethylammonium iodide, p-stearoamidophenyltrimethylammonium sulphate, b -stearoamidoethyldiethylamine methosulphate (cf. Specification 294,582, [Class 2 (iii), Dyes &c.],) and b -hydroxyethyl-N-octadecylmorpholinium bromide.  The following examples are specified: (1) Cotton, dyed with the dyestuff 4-chloro-2-toluidine --> (on the fibre) the 4-bromo-o-anisidide of 2 : 3-oxynaphthoic acid, is treated for 10 minutes with a boiling aqueous solution containing small amounts of sodium hydrosulphite, sodium carbonate and b -hydroxyethyl-N-octadecylmorpholinium bromide; the dyeing is stripped to a pale yellow which may be cleared by a mild chlorine treatment.  (2) The quaternary ammonium salt is (1) is replaced by octadecylpyridinium bromide.  (3) Cotton, dyed with the dyestuff 5-chloro-2-toluidine --> (on the fibre) the 4-bromo-o-anisidide of 2 : 3-oxynaphthoic acid, is treated for 30 minutes with a boiling aqueous solution, slightly acid with acetic acid, containing small amounts of sodium formaldehydesulphoxylate and cetyltrimethylammonium bromide or cetyl pyridinium bromide; the dyeing is similarly stripped and a mild chlorine clearing treatment may be used.  (4) Degummed natural silk, dyed with the dyestuff 4-chloro-2-toluidine --> (on the fibre) the 4-bromo-o-anisidide of 2 : 3-oxynaphthoic acid, is treated for 30 minutes with an aqueous solution at 90-95 DEG  C., slightly acid with acetic acid, containing small amounts of sodium formaldehydesulphoxylate and cetyltrimethylammonium bromide; the dyeing is stripped to a pale yellow.  (5) Cotton, dyed with the dyestuff 4-chloro-2-toluidine --> (on the fibre) the 5-chloro-2-toluidide of 2 : 3-oxynaphthoic acid is treated for 30 minutes with a boiling aqueous solution neutralized with acetic acid containing small amounts of sodium formaldehydesulphoxylate and cetyltrimethylammonium bromide; the dyeing is completely stripped.  (6) Cotton, dyed with the dyestuff 3-amino-6-benzoylamino-4-methoxytoluene --> (on the fibre) the anilide of 2 : 3-oxynaphthoic acid, is treated for 1 hour with a boiling aqueous solution containing small amounts of sodium formaldehydesulphoxylate, acetic acid and b -diethylaminoethyloleylamide acetate; the dyeing is stripped to a white with a yellow tinge and may be cleared to a perfect white by treatment for 5 minutes in a mild chemick solution. Specifications 362,060 and 366,961 also are referred to.  b -hydroxyethyl-N-octadecylmorpholinium bromide is obtained by reaction of b -hydroxyethylmorpholine with octadecyl bromide at 140-145 DEG C.  Cetyl - trimethyl - and - triethyl - ammonium bromides and iodides are prepared by reaction of cetyl bromide or iodide with trimethylamine or triethylamine in alcoholic solution at 100 DEG  C. Octadecyltrimethylammonium iodide is obtained by reaction of octadecyl iodide with trimethylamine.