Patent GB-576296-A (GB)
Title: Improvements in the dyeing of textile materials
IPC: D06P1/22
Filed: 1944-03-14
Abstract: Natural or artificial cellulosic textile materials, e.g. of cotton, linen, or regenerated cellulose are dyed with vat or sulphur colours with the use of aqueous sodium chlorite to effect the oxidation on the impregnated material.  The chlorite is optionally used in presence of an acid, preferably acetic acid, advantageously with an addition of an alkali phosphate, or with the use of a buffer salt, e.g. sodium bicarbonate, in which case a detergent, e.g. tetrasodium pyrophosphate, is advantageously added.  Bright dyeings especially fast to washing are obtained. The chlorite concentration and the pH range may each be varied considerably without injuring the fibres and an appropriate alkaline pH range is 8 to 10.5.  In examples: (1) a twill is padded with a mixture of Carbanthrene khaki 2G, Ponsol olive AR and Carbanthrene brown AG, passed first three times through an aqueous solution at 140 DEG  F. containing sodium hydrosulphite and caustic soda, then three times through an aqueous solution at 140 DEG F. of sodium chlorite acidified with acetic acid to pH 4.3, washed and soaped; (2) a poplin is padded with the dyestuff composition of (1), passed three times through a hydrosulphitecaustic soda bath as in (1), washed cold, passed four times through an aqueous sodium chlorite bath at 140 DEG  F., acidified with acetic acid, washed and soaped; (3) the process of (2) is modified to effect soaping between the chlorite baths; (4) a poplin is padded with the dyestuff composition of (1), is passed eight times through a hydrosulphite-caustic soda bath as in (1), washed in cold water, passed three times through aqueous sodium chlorite at 140 DEG  F., acidified with acetic acid, washed in hot water and soaped; (5) a mercerized yarn is impregnated with an aqueous solution at 120 DEG F. containing sodium hydrosulphite caustic soda, the dioctyl ester of sodium sulphosuccinate and Ponsol blue BF, treated with an aqueous solution at 140 DEG  F. of sodium bicarbonate containing sodium chlorite, washed with hot water and then with a warm aqueous solution of "Hexatol"; (6) a heavy twill and herringbone, similarly impregnated with an Indanthrene yellow G solution is washed with cold water, passed four times through an aqueous solution at 140 DEG  F. containing sodium bicarbonate and sodium chlorite, washed at 180 DEG F., passed through a soap-sodium carbonate solution and then through hot and cold water; (7) a spun rayon fabric is padded with a mixture of Indanthrene olive green BWP and Indanthrene brown RAP, treated for 20 mins. with an aqueous solution at 140 DEG  F. containing caustic soda and sodium hydrosulphite, washed, passed four times through an aqueous solution at 140 DEG  F. containing sodium chlorite and sodium bicarbonate at a pH of 8.3 to 8.45, and washed; (8) poplin dyed with a mixture of Katigen brown R and Katigen brown W is passed three times through an aqueous sodium chlorite solution at 30 DEG  F., acidified with acetic acid, washed and soaped; (9) heavy twill, impregnated with Katigen blue green GA-CF, is washed with cold water, passed four times through an aqueous solution at 130 DEG  F. containing sodium bicarbonate and sodium chlorite, washed and soaped.