GB571325A - Improvements in and relating to dyeing operations - Google Patents

Abstract

Textile and other materials such as viscose sheet, paper, wood veneer and composite sheet containing or composed of dyeable materials, which have had vat dyestuff applied by pigment padding are subjected to treatment with a reducing liquor while sandwiched between two surfaces, preferably impermeable to <PICT:0571325/IV/1> air and moisture, and the reduced dye is subsequently oxidised in the usual manner. The reducing operation may be carried out continuously, e.g. between two endless bands or surfaces, one of which bands may pick up the reducing liquor or the liquor may be run or sprayed on to the fabric as it enters the bands. Alternatively, the reduction may be effected between the surfaces of a cylinder or cylinders and an endless band passing round them or between non-moving surfaces. A suitable apparatus comprises a steel cylinder 2, having an internal steam space 3, and an endless rubber blanket 1. That part of the blanket not carried by the cylinder is supported by guide rollers, certain of which act as immersion rollers in a rectangular box 4 containing the blanket washing liquor, which may be heated by live steam admitted through pipes 6 and 7. A steam-heated drying cylinder 8 maintains the temperature of the blanket. The cloth 11 passes through the reducing solution in the box 9 under the roller 10 and on to the blanket moving round roller C11. Surplus liquor is removed from the cloth by the doctor 13. The cloth then passes between the sandwiching surfaces of the blanket and the cylinder and emerges at the roller C1 whence it passes to the continuous washing, oxidising and soaping devices to complete the dyeing operation. In examples: (1) cotton poplin is padded with an aqueous bath containing Caledon jade green, sulphonated castor oil and locust bean gum, the dye reduced with alkaline solution hydrosulphite in the apparatus described above and the dyeing finished as usual; (2) cotton tussore is padded with an aqueous bath containing Caledon brilliant blue, sulphonated castor oil and locust bean gum, the dye reduced with an alkaline sodium hydrosulphite solution containing a sulphonated fatty alcohol such as sulphonated oleyl alcohol in the apparatus described above and the dyeing finished as usual.