Patent GB-446595-A (GB)
Title: Process for dyeing leather
IPC: D06P3/32
Filed: 1935-01-01
Abstract: Acid wool and mordant dyes, dyeing with; azo dyes, copper compounds of.--Leather is dyed a level fast shade with a copper compound of an azo dyestuff of the general formula <FORM:0446595/IV/1> wherein R1 represents a 4 : 4<1>-diamine of the diphenyl series containing at least one sulphonic group, R2 a dihydroxyaryl compound capable of coupling twice, R3 a diazotizable amine containing a lake-forming group and R4 a coupling component.  Thus R1 may be a benzidinemono-or di-sulphonic acid or a halogen, alkyl or nitro derivative thereof; R2 may be 1 : 3-dioxybenzene or its 4- or 5-carboxylic acid, 1 : 2 : 3-trioxybenzene-5-carboxylic acid, 1 : 5- or 2 : 6-dioxynaphthalene, or a sulphonic acid or halogen, alkyl or nitro derivative thereof capable of coupling twice; R3 may be an o - aminophenol, o - aminonaphthol, o - amino-alkoxybenzene, o - aminoalkoxynaphthalene, anthranilic acid, o-aminonaphthoic acid, aminosalicylic acid or a sulphonic acid or halogen, alkyl or nitro derivative thereof; R4 may be a phenol or amine of the benzene or naphthalene series or a sulphonic acid or halogen, alkyl or nitro derivative thereof or an azo dyestuff capable of coupling.  The conversion of the dyestuff into the copper compound may be effected by treating it simultaneously with its production or in substance or in the dyebath with an agent yielding copper or by allowing such agent to act on an intermediate dyestuff containing a lake-forming group.  Specified agents yielding copper are the chloride, sulphate, acetate and tetrammine cupric sulphate.  The following examples are specified: (1) Neutralized chrome leather is dyed a level full brown of good fastness by tumbling it for 40 minutes with an aqueous solution at 60 DEG  C. of the copper compound of the trisazo dyestuff 2-amino-phenol-4-sulphonic acid --> 1 : 3-dioxybenzene \sM 4 : 4<1> - diaminodiphenyl - 2 : 2<1> - disulphonic acid --> 3-aminophenol.  (2) Well fulled vegetable-tanned sheep or goat leather is dyed by treatment as in (1) followed by an addition of formic acid and continued treatment for 10--15 minutes; dyeing may also be effected by brushing methods.  A table is also given showing the shades obtainable with the copper compounds of various dyestuffs, specified components, additional to those in (1) above, being (R1), 4 : 4<1>-diaminodiphenyl-3-sulphonic and 3 : 3<1>-disulphonic acids; (R2), 1 : 3- dioxybenzene-4-carboxylic acid; (R3), 4-nitro-2-aminophenol, 4-chloro-2-aminophenol, 2-aminophenol-4 : 6-disulphonic acid, 4 : 6-dinitro-2-aminophenol and 6 - amino - 1 - oxy - 2 - car-boxybenzene-4-sulphonic acid; (R4), 1 : 3-dioxybenzene, 1 : 3-diaminobenzene, 2 : 4-diaminotoluene, 1 : 3 - diaminobenzene - 4 - sulphonic acid, 2-phenylamino 8-naphthol-6 sulphonic acid (coupled alkaline), 1 : 8 : 3 : 6-, 2 : 8 : 3 : 6- and 2 : 5 : 1 : 7-aminonaphtholdisulphonic acids (coupled alkaline), 2 : 5 , 7- and 2 , 8 : 6-aminonaphtholsulphonic acids (coupled alkaline), 2-phenylamino - 5 - naphthol - 7 - sulphonic acid (coupled alkaline) and the dyestuffs 2-aminophenol-4-sulphonic acid --> 1 : 3-dioxybenzene, 4-nitraniline --> (acid) 2 : 8 : 6-aminonaphtholsulphonic acid or 1 : 8 : 3 : 6-aminonaphtholdisulphonic acid, 2 : 8 : 6-aminonaphtholsulphonic acid --> 1 : 3-diaminobenzene. Specification 12932/15, [Class 2 (iii)], is referred to.