Patent GB-574814-A (GB)
Title: Process for pigmenting fibrous materials and the products produced
IPC: D06P1/44
Filed: 1943-06-22
Abstract: Water-absorbent fibrous material is pigmented by treatment with an aqueous alkaline or salt solution of a coagulable hydrophilic colloid, insoluble in water, but soluble in an aqueous alkali or salt solution, coagulating the colloid to form a gel and precipitating inorganic pigment in situ within the gel.  Such precipitation may be effected simultaneously with or subsequent to the coagulation of the colloid.  When the precipitation is effected from a water-soluble copper salt, the material is moisture-proofed.  The pigment may be formed by reaction of a water-soluble compound contained in the solution of the colloid with a second such compound applied during or after the coagulation.  Alternatively, the material carrying the gel may be treated with an aqueous solution of a heat-convertible inorganic compound and the material be then heated to convert such compound into the desired pigment.  Specified water - absorbent fibrous materials are textiles, felts and papers of natural fibres, e.g. cotton, flax, ramie, jute, natural silk or wool and/or of hydrophilic artificial fibres, e.g. regenerated cellulose or alkali-soluble cellulose ether fibres.  Specified hydrophilic colloids are casein, phenolic A resin, cellulose suitably degraded by acids, alkalies or oxidizing agents, cellulose xanthates, cellulose thiourethanes and alkali-soluble alkyl, hydroxyalkyl or carboxyalkyl celluloses.  In examples: (1) a cotton fabric is padded with an aqueous solution containing sodium hydroxide and an alkali-soluble, water-insoluble, hydroxyethylcellulose, partially dried at 45 DEG C., passed through an aqueous solution at 49 DEG  C. containing ferric chloride, chromium fluoride, copper sulphate and hydrochloric acid to coagulate the hydroxyethyl cellulose, treated with an aqueous solution of sodium carbonate to precipitate the pigment, washed and dried to obtain a khaki mildew-proofed fabric; (2) a cotton fabric is printed with an aqueous solution containing sodium hydroxide and hydroxyethylcellulose as in (1), passed through an aqueous solution at 49 DEG  C. containing copper sulphate, chromium acetate, manganous chloride and hydrochloric acid to coagulate the hydroxyethyl cellulose, treated with an aqueous solution containing sodium carbonate and sodium hypochlorite to precipitate the pigments, washed and dried; (3) a cotton fabric is padded with an aqueous solution containing sodium hydroxide, sodium tannate and hydroxyethylcellulose as in (1), partially dried to coagulate the hydroxyethylcellulose, passed through an aqueous solution containing ferrous and chromium acetates, wrung out, treated with an aqueous solution containing sodium carbonate and sodium hydroxide to precipitate the pigments, washed and dried; (4) a fabric is printed with an aqueous solution containing sodium hydroxide, barium hydroxide and an alkali-soluble, water-insoluble, acid-degraded cellulose and passed through an aqueous solution of sulphuric acid to coagulate the cellulose and precipitate the barium sulphate simultaneously; (5) and (6) the barium hydroxide in (4) is replaced by (5) potassium dichromate and (6) sodium sulphide, and the sulphuric acid by acetic acid containing lead acetate, to precipitate a lead chromate and a lead sulphide pigment respectively.  The Specification as open to inspection under Sect. 91 (4) (a) comprises also the use of coagulable hydrophilic colloids other than those of the type defined above, e.g. starch, gelatine and water-soluble gums, resins or cellulose ethers.  This subject-matter does not appear in the Specification as accepted.