Improvements in the Production of Brown Shades on the Fibre, with, or without, White, or Coloured, Discharge Effects.

摘要

17,241. Johnson, J. Y., [Badische Anilin & Soda Fabrik]. Aug. 25. Dyeing.-Full-brown shades, fast to washing, are produced on the fibre without weakening thereof, by oxidizing, with a chlorate in the presence of a vanadium compound, p-phenylenediamine, or a homologue or isomer thereof, in the presence of insufficient mineral acid to combine with the whole thereof. White or coloured discharges may be obtained. If p-phenylenediamine hydrochloride is used, a greater part or the whole of the hydrochloric acid is neutralized by, for instance, sodium acetate or formate or by an alkali. An example of a bath is as follows : p-phenylenediamine is dissolved in hot water, and there is added a quantity of cold water, then suitable quantities of rongalite C (sodium formaldehydesulphoxylate), aqueous solutions of sodium chlorate and ammonium chloride, glycerine-tartar-emetic solution, and then more cold water. A small quantity of ammonium vanadate is added shortly before the bath is to be used. Only such amount of the bath should be prepared as can be used within a short time. The rongalite C keeps the bath colourless or nearly colourless for some time. In its place, other bodies such as hydrosulphite N.F. (formaldehyde-hyposulphite) or a bisulphite may be used. The glycerine-tartar-emetic solution may be omitted, but it also increases the stability of the padding-mixture, and further, it is stated, material padded with the bath containing it keeps better when the material has to be kept before being worked up. It is prepared by dissolving tartar-emetic in a mixture of glycerine and water. Instead of a vanadium salt being added to the bath, the material may be treated first with a vanadium compound, such as vanadium ferrocyanide. After being treated, the material should be dried rapidly without being too strongly heated and can then be steamed, in a Mather-Platt apparatus, for example, if a uniform shade is desired. For discharging, pastes containing a sulphite, bisulphite, hyposulphite (hydrosulphite), or the like may be used. For instance, the treated and dried material may be printed with a paste containing potassium sulphite, sodium acetate, and hydrosulphite N.F., and then steamed. A pure white on a full-brown background is obtained. Coloured effects can be produced by adding to the paste a basic dye which is stable against hydrosulphite, and can be fixed by tannin with the addition of sodium acetate, chalk, or the like. The paste should contain less reducing-matter than is used for discharging azo dyes, the procedure being otherwise the same. The usual precautions should be followed, such as adding phenol or aniline to the paste.