GB866329A - Coloured cellulose acetate textile and other materials - Google Patents

Abstract

A solution of cellulose triacetate in a watermiscible solvent is extruded into a water-miscible coagulant, the extruded product is washed with water until substantially free from the solvent, and the water-wet product is coloured by treatment with an aqueous solution of a watersoluble metallized dye derived from about one atomic proportion of metal and two molecular proportions of an unsulphonated monoazo- or monoazomethine dye in which the azo or azomethine group unites two carbon atoms each of which is directly attached to a carbon atom carrying a hydroxyl group. Preferably the filaments are allowed to take up the dye substantively from an aqueous dye bath. The filaments may be in the form of a tow of at least 1,000 continuous filaments and a total denier of at least 5,000, which is impregnated with an aqueous solution of the dye, steamed, rinsed, and dried. After dyeing, the material may alternatively be dried prior to washing. In a preferred method, a solution of cellulose triacetate in acetic acid is extruded into aqueous acetic acid and the water-wet filaments are coloured by the above treatment. Desirably, these filaments are in the form of a tow of at least 1,000 continuous filaments and a total denier of at least 5,000 and take up the dye substantively while travelling lengthwise in contact with an aqueous solution of the dye moving in the same direction. The tow so treated may be a continuous running tow, or hanks of tow may be treated batchwise. The filaments may be stretched, immediately after their formation, while still in contact with the aqueous acetic acid of the coagulating bath, to improve their mechanical properties. If preferred, dye may alternatively be applied to staple fibres cut from a wet tow. Numerous dyes are specified, and suitable apparatus for dyeing tows is described (see Group IV(c)). The Provisional Specification refers also to the dyeing of cellulose acetate and triacetate with direct cotton dyes, acid wool dyes, mordant dyes and cellulose acetate disperse dyes, and to the use of vat dyes and of aromatic amines which are convertible into colouring matter on the material by oxidation or may be diazotized, and of azo coupling components which may be coupled with diazo compounds to form azo dyes. Specification 858,532 is referred to.ALSO:<PICT:0866329/IV(c)/1> In a dyeing apparatus suitable for the treatment of a continuous running tow of filaments, or the batch-wise treatment of hanks of filaments, the tow 19 is drawn from container 12 by the driven pulleys 11-16 through a series of U-tubes 1-4, immersed in a tank 5 heated e.g. by a steam coil (not shown). The drag on the tow is reduced by protuberances 6 on the inside of each U-tube. Dye liquor from tank 7 and valved pipe 8 passes co-currently through the U-tubes, and is discharged at outlet 10, the dyed tow being squeezed between rolls 17 and collected in container 18. Specifications 858,532 is referred to.