GB466215A - Process for dyeing leather - Google Patents

Abstract

Azo dyes; acid wool dyes, dyeing with.--Leather, whether chrome-, vegetable- or semi-chrome-tanned, is dyed with monoazo dyes of good solubility obtainable by coupling a diazotized sulphonated a - or b -naphthylamine or a derivative thereof with a 1 : 3-phenylene diamine which may be substituted in the nucleus or may be substituted in one or both amino groups, e.g. by alkyl, acyl, hydroxyalkyl, alkylsulphonic acid or alkylcarboxylic acid groups. Other acid or substantive dyes may be used in addition. The following examples are specified: (1) Chrome tanned calf leather is treated for 45 minutes in a rotary drum with an aqueous solution at 60 DEG C. of the dyestuff obtainable by heating 1 mol. of the dyestuff, 1-naphthylamine-3 : 6 : 8-trisulphonic acid --> (alkaline) 2 : 4-toluylenediamine, with 2 mols. of glycolchlorhydrin under pressure at 120--130 DEG C., fat liquor is added, the drum is rotated for a further 30 minutes, an aqueous solution of formic acid is then added and the rotation continued for 15 minutes; the leather is then stroked out, dried, chipped, stretched, nailed and fluffed; the reddish brown dyeing can be sharpened without uncovering undyed parts; (2) chrome tanned neutralized calf leather is dyed in the usual manner in a bath containing the dyestuff, 1-naphthylamine-3 : 7-disulphonic acid --> (acid) 2 - 4-toluylenediamine-5-sulphonic acid, and the dyestuff obtainable according to Specification 447,775 by coupling diazotized 4-nitro-1 : 3-diaminobenzene with the copper complex compound of the dyestuff, 2-anisidine-4-sulphonic acid --> resorcinol and the dyed leather is fatted; the yellowish brown dyeing can be glazed without the surface becoming cloudy or flocky. A table is also given showing the shades obtainable with various combinations of diazo and coupling components, additional specified diazo components being 1-naphthylamine-4-and 5-sulphonic acids, 1-naphthylamine-3 : 6-and 4 : 8-disulphonic acids, 2-naphthylamine-6-sulphonic acid, 2-naphthylamine-3 : 6-, 4 : 8-, 5 : 7- and 6 : 8-disulphonic acids, 4-nitro-1-naphthylamine-5-sulphonic acid and 4-acetyl-amino-1-naphthylamine-6-sulphonic acid and additional coupling components being 2 : 4-toluylenediamine-5-sulphonic acid p (coupled alkaline), 2 : 4-toluylene diamine (coupled alkaline and the dyestuff in one example being after-treated with b -chlorethanesulphonic acid), 2 : 6 - toluylenediamine - 4 - sulphonic acid (coupled acid and coupled alkaline), 3-aminophenylaminoacetic acid (coupled acid), 4-nitro-1 : 3-diaminobenzene (coupled acid) 1-acetylamino - 3 - b - oxyethylaminobenzene (coupled acid), 1 : 3 - diaminobenzene (coupled acid and coupled alkaline), 4-chloro-1 : 3-diaminobenzene (coupled alkaline) and 2 : 4-toluylenediamine-6-sulphonic acid (coupled acid and coupled alkaline).