Patent GB-560284-A (GB)
Title: Process for chlorinating textiles dyed with dyestuffs sensitive to chlorine
IPC: D06P1/56
Filed: 1941-12-23
Abstract: To avoid detrimental action on the dyeing when chlorinating textile materials dyed with dyestuffs sensitive to chlorine, e.g. direct dyes, azo dyes produced upon the material, or sulphur dyes, there is first produced on the materials, in coherent form, a water-insoluble resinous condensation product from formaldehyde and a compound capable of condensing therewith, e.g. urea, thiourea, biuret, phenylurea, melamine, a phenol or aniline. Specified dyed textile materials are cotton, linen and regenerated cellulose and especially mixtures thereof with wool, which are chlorinated to prevent felting or shrinking of the wool.  The process is also applicable to the bleaching by chlorination of undyed cellulose fibres in association with dyed cellulose fibres carrying a water-insoluble condensation product as above.  Mixed materials of untreated wool and dyed cellulose fibres carrying such a condensation product may also be chlorinated.  In examples: (1) viscose staple fibre, dyed with Direct brown M, is immersed in a solution made by adding ammonium chloride to an aqueous solution of dimethylolthiourea, with or without dimethylolurea, at a pH of 6 and the impregnated fibre is centrifuged, dried or hardened at 120 DEG  C., worked up with an equal quantity of dyed wool into yarn which is then made unshrinkable and non-felting by treatment for 20 minutes with an aqueous solution containing sodium hypochlorite and sulphuric acid, rinsing, treatment with a dilute aqueous solution of sodium bisulphite and again rinsing; (2) loose regenerated cellulose staple fibre, dyed with Direct fast scarlet SE, is immersed in an aqueous solution containing dimethylolurea, ammonium chloride and a mixture of sulphonated and unsulphonated monocetyl phthalate and the impregnated material is dried or hardened at 120 DEG  C. and mixed with loose wool, dyed with Cloth fast red R, the mixture being worked up into yarn which is chlorinated as in (1); (3) cotton yarn, dyed with a sulphur dyestuff, such as Pyrogene indigo 5G, Pyrogene deep black T, Pyrogene blue 2R, Indocarbon CL or Pyrogene green 3G, is impregnated as in (1) with dimethylolthiourea and incorporated as effect threads in a cotton fabric which is then bleached with a cold alkaline hypochlorite solution without affecting the colour of the dyed threads; (4) viscose staple fibre, dyed with Melantherine BH, is treated with an aqueous solution containing dimethylolurea and/or dimethylolthiourea, ammonium chloride and a mixture of sulphonated and unsulphonated monocetyl phthalate, centrifuged, dried, heated for 40 minutes at 110 DEG  C., worked up into yarn and incorporated as effect threads in a cotton fabric which is then bleached as in (3); alternatively, the treated staple fibre is mixed with loose wool and the mixture made into a knitting yarn which is chlorinated as in (1); the dyestuffs used for the cellulose fibres in examples (1), (2) and (4) may be replaced by Direct fast red F, Direct sky blue, green shade, or Cotton yellow CH or by dyes such as Rosanthrene BN, Rosanthrene bordeaux B or Para black R, the dyeings of which have been developed on the fibre by diazotization and coupling with b -naphthol or by treatment with diazotized p-nitraniline; (5) viscose artificial silk yarn, dyed with Direct sky blue, green shade, Direct fast scarlet WS, Melantherine BH, Direct fast orange SE or Pyrogene indigo, is impregnated with a solution made by adding dimethylolurea, ammonium chloride, a mixture of sulphonated and unsulphonated monocetyl phthalate and water to an aqueous solution of a melamine-formaldehyde condensation product, centrifuged, dried, heated for 40 minutes at 110 DEG  C. and woven with undyed viscose artificial silk into a fabric which is treated with an aqueous solution of sodium hypochlorite to bleach the undyed fibres.