| 摘要 |
Wool is bleached and shrink-proofed by introducing and submerging it in water, the water and the resulting treating bath being at 13 DEG -25 DEG C., introducing progressively a dilute aqueous solution of an acid with continuous agitation until a pH of 2-4,5 is reached, con-tinuing agitation, introducing slowly an aqueous chlorite solution of pH 8-9 and free from ClO2 until the wool turns pink whereby the pH of the chlorite solution is lowered without evolution of ClO2 and the bath remains sub-stantially colourless throughout the treatment, rinsing with water and treating the pink wool with an aqueous reducing solution at a tempera-ture of 45 DEG -60 DEG C. The acid may be phosphoric, sulphuric, formic or acetic acid and may be in the form of a dilute aqueous solution having a concentration of 5-20% by weight. When acetic acid is used 5-40% of sodium acetate based on the weight of the undiluted acid may be added to the solution to serve as a buffer at the indicated pH. The chlorite solution may be an aqueous solution of an alkali metal chlorite having a concentration of 5-20% by weight and the reducing solution may be a 0,2-1,5% by weight aqueous solution of an alkali metal bisulphite or hydrosulphite or a mixture thereof. The treating bath and bleaching solution may also contain 0,02-0,1% by weight of a wetting agent, e.g. RCOOCH2CH2SO3Na, RCONHCH2CH2SO3Na, RCH2SO4Na or RCH2SO3Na in which R is an alkyl or alkenyl radical containing 12-20 carbon atoms, an alkyl aryl sulphonate, an alkyl p phosphate salt, lauryl polyethoxy ether or n-octadecyl diso-dium sulphosuccinamate, and 0,005-0,05% by weight of hydroquinone may be added to the acidic chlorite treating bath. The treatment may be combined with an additional chlorina-tion treatment with a sodium hypochlorite solution followed by treatment with sodium hydrosulphite solution or with a treatment with a proteolytic enzyme, e.g. papain or trypsin, which may be added to the reducing solution together with 0,2-1% by weight of sodium bicarbonate. Specifications 561,475 and 743,927 are referred to. |
