Patent GB-438398-A (GB)
Title: Process for through dyeing leather, especially chrome leather
IPC: D06P3/32
Filed: 1934-12-07
Abstract: Monoazo dyes; acid wool dyes, dyeing with.--Leather, especially chrome leather, is dyed throughout with a salt of an amino- or alkylamino-azobenzenesulphonic acid which contains an acylamino or a further amino or alkylamino group or several of these groups or one or more nitro groups and may be substituted in the benzene nuclei by carboxyl, halogen or any neutral or acid substituent, but contains no oxy group in o-position to the azo group and is not prepared from monodiazotized 4-nitro-1 : 3-diaminobenzene or an alkyl or alkoxy derivative thereof.  The neutralized hides are dyed in the rotary cask with 150--200 per cent of water at 65 DEG  C., a solution of 1--2 per cent of the dyestuff being introduced through the hollow axle, the fat liquor being added after 45 minutes, and the cask being then kept in motion for a further 45 minutes, or longer in the case of heavy hides.  In examples chrome leather is dyed with the sodium salts of the following dyestuffs: (1) 3-nitraniline --> 2-ethylamino-1-methylbenzene-4-sulphonic acid, (2) 4-nitro-2-aminobenzenesulphonic acid --> 4-chloro-3 : 5-diaminobenzenesulphonic acid, (3) 5-nitro-2-aminobenzenesulphonic acid --> 3-diethylaminobenzenesulphonic acid, (4) 2 : 4-dinitraniline --> 2 : 6-diaminobenzene-1 : 4-disulphonic acid.  A table is also given showing the shades obtainable on the surface and in the interior of leather with the sodium salts of the following dyestuffs, viz., the 2-, 3- and 4-nitro-, 2 : 4-dinitro-, 3-nitro-6-methoxy-, 4-nitro-2-methoxy- and 2-chloro-4-amino-derivatives of 3<1>-methyl-4<1>-ethylaminoazobenzene-6<1>-sulphonic acid, 4-nitro-3<1>-methyl-4<1>-ethylaminoazobenzene-2 : 6<1> and 3 : 6<1>-disulphonic acids, 3-nitro-3<1>-methyl-4<1>-ethylaminoazobenzene-6 : 6<1>-disulphonic acid 2 - nitro - 3<1> - methyl - 4<1> - ethylaminoazobenzene - 4 : 6<1> - disulphonic acid, the 2 : 4-dinitro-, 4-chloro-2-nitro-, 2-nitro-4-methyl-, 2-nitro-4-amino-, 4-acetyl-ethyl-amino-, 3 - chloro - 4 - acetylamino-, 2 - nitro - 4 - acetylamino- and 4-methyl-3-acetyl-ethyl-amino-derivatives of 4<1>-diethylaminoazobenzene-6<1>-sulphonic acid, the 2-nitro-, 2-nitro-4-methyl-, 3-nitro-6-methoxy-, 2 : 6-dichloro-4-amino-, 4-methyl - 3 - acetyl - ethyl - amino-, 2 - methyl-5 - acetyl - ethyl - amino - and 2 - nitro - 4-amino-derivatives of 3<1>-chloro-2<1> : 4<1>-diaminoazobenzene - 6<1> - sulphonic acid, the 4-nitro-3<1>-chloro- and 4-3<1>-dimethyl derivatives of 2<1> : 4<1> - diaminoazobenzene - 2 : 6<1> - disulphonic acid, the 3-nitro-3<1>-chloro-, 3 : 4-dichloro-3<1>-methyl-, and 3-nitro-3<1>-methyl-derivatives of 2<1> : 4<1> - diaminoazobenzene - 6 : 6<1> - disulphonic acid, the 2-nitro-4-chloro-, 2-nitro-4-methyl-, 2 - nitro - 4 - ethoxy -, 2 - nitro - 4 - amino-, and 4 - methyl - 3 - acetyl - ethyl - amino-derivatives of 3<1>-methyl-2<1> : 4<1>-diaminoazobenzene - 6<1> - sulphonic acid, 2 - nitro - 3<1>-methyl - 2<1> : 4<1> - diaminoazobenzene - 4 : 6<1>-disulphonic acid, the 5<1>-acetylamino- and 5<1>-methoxy derivatives of 2<1> : 4<1>-diaminoazobenzene - 2 : 5 - disulphonic acid, 4 - nitro - 5<1> phenoxy - 2<1> : 4<1> - diaminoazobenzene - 2 : 4<11> - disulphonic acid, 3 - nitro - 5<1> - phenoxy-2<1> : 4<1> - diaminoazobenzene - 6 : 4<11> - disulphonic acid, 3-nitro-2<1> : 4<1>-diaminoazobenzene 6-sulphonic acid-6<1>-carboxylic acid and the 4-nitro- and 2 : 4-dinitro-derivatives of 2<1> : 4<1>-diaminoazobenzene - 3<1> : 6<1> - disulphonic acid. Specifications 22021/06, [Class 2], and 216,971, [Class 2 (iii)], are referred to as describing certain intermediates for use in making the dyestuffs.  The Specification as open to inspection under Sect. 91 comprises also the use of the dyestuff 3-chloro-6-oxy-2<1> : 4<1>-diamino-5<1>-acetylaminoazobenzene-4-sulphonic acid. This subject-matter does not appear in the Specification as accepted.