GB419941A - Treatment of leather - Google Patents

Abstract

Acid, basic or substantive dyes, dyeing with.--Leathers (not including furs) which have been tanned exclusively or in part with vegetable tanning agents are treated over the whole surface or a part thereof with an aqueous solution of a quaternary ammonium salt containing a saturated aliphatic chain of not less than 10 carbon atoms but no hydroxyl group, and thereafter, if desired, are dyed or stained with an aqueous solution of an acid, basic or direct dyestuff. Specified quaternary ammonium salts are dodecyltrimethylammonium chloride, cetyltrimethylammonium chloride, octadecylpyridinium iodide, stearylpyridinium bromide (cf. Specification 379,396), stearamidophenyltrimethylammonium methyl sulphate and methylcetylpiperidinium methyl sulphate. Specified dyestuffs are Nigrosine G, Naphthalene black 12B, Lissamine green SF, Orange II, Croceine scarlet 3B, Tartrazine N and Cardinal red. The Provisional Specification refers also to the use of Naphtharene orange G. When the treatment with the quaternary salt solution is by spraying, stencilling or printing, the treated portions of the leather show, in general, much less affinity for the dyestuffs, whereas when an immersion treatment is used the leather may show an increased affinity therefor. The following examples are specified. (1) Dry skivers (sumac grain sheepskin splits) are sprinkled with a 1 per cent solution of stearyl-pyridinium bromide; when the spots are dry the skivers are immersed in an aqueous solution containing Nigrosine G and Croceine scarlet 3B, struck out, dried, and, if desired, treated with an aqueous season to obtain scarlet spots on a black ground. (2) Vegetable-tanned sheep-skins, dyed with Orange II, are spray-stencilled with a 1 per cent solution of cetyl trimethyl-ammonium chloride, dried, sprayed with a solution of Cardinal red, dried and finished to obtain orange spots on a brown ground. (3) Dry semichrome Persian suedes are immersed for 30 minutes in a 1 per cent solution of octadecylpyridinium iodide, rinsed, treated with a warm solution of Lissamine green SF, fat-liquored and dried out to obtain a much stronger dyeing than is obtainable without the pretreatment. Specification 294,890, [Class 15 (ii)], also is referred to. Stearamidophenyltrimethylammonium methyl sulphate is obtained by condensing asymmetrical dimethyl - p - phenylenediamine with stearoyl chloride and treating the product with dimethyl sulphate. Dodecyltrimethylammonium chloride is obtained by reaction of dodecyl chloride with trimethylamine. Methylcetylpiperidinium methyl sulphate is obtained by treating with dimethyl sulphate the cetylmethylpiperidine produced by intertion of N-methylpiperidine (2 mols.) with cetyl bromide (1 mol.).