US1690318A - Process of dyeing leather with acid azo dyestuffs - Google Patents

Description

Patented Nov. 6, 1928.

V UNITED STATES BARTHOLOMKUS VOSSEN, OF HOCHST-ON-THE-MAIN, GERMANY, ASSIGNOR TO GRAS- SELI-I DYESTUFF CORPORATION, WARE.

OF. NEW YORK, N. Y., A CORPORATION- OF DELA- PROCESS OF DYEING LEATHER WITH: ACID AZO DYESTUFFS.

No Drawing" IArplication filed January 23, 1926, Serial No. 83,389, and in Germany February 3, 1925.

I have found that deep and full brown dyeings can be produced on leather tanned by any method and this with such a depth of I shade as could h therto not at all be obtained in the art of dyeing leather by means of acid azo dyestuffs or only by means of mixtures of various dyestuffs of this kind, it there are used dyestuffs formed according to the following scheme:

I II III IV amine-mon-su1fonated-aminonaphtholsu1fonic acid -ami1: resorcinol or naphthylanunsulfonic acid In this scheme the term amine (I and IV) comprises: a

All diazotizable aromatic amines, aminohydroxy and amino-azo compounds and also their substitution products including the sulfonic acids and carboxylic acids, for instance aniline, p-nitraniline, aminoazoben zene, 2- chlor-fi-toluidine-4-sulfonic acid, p-nitro-oaminophenol, picramic acid, naphthionic acid, or the like;

The term non-sulfonated resorcinol (II) comprises:

Resorcinol and its substitution products including the carboxylic acids with the exception of the respective sulfonic acids, for in- 1 stance resorcinol, chlorresorcinol, 1.3.4-resorcylic acid or the like;

The acids mentioned under III comprise: Aminonaphtholmonoor disulfonic acids as well as naphthyl-aminemonoor disulfonic acid} for instance 1-amino 8-hydroxynaphthalene-3.6-disulfonic acid acid), l-amino 8 hydroxynaphthalene 4.6 disulfonic acid (K acid), 1-amino-8-hydroxynaphthalene-t sulfonic acid, and the technical mix-,,

ture of 1-naphthylamine-6-sulfonic acid and 1-naphthylam'ine-7-sulfonio acid; and the arrow points from the amino compound which is diazotized to the compound with which the i diazotized amino compound is coupled.

Some of the 'dyestufis of the aforementioned type are already known, but they were hitherto only described as being suitable for use as acid or chrome mordant dyestuffs for wool. They were, however, not adopted to a great extent, probably owing to their unsatisfactory levelling power and the insuflicient fastness of the dyeings obtained therewith on wool.

It could not at all be foreseen that the dyestuffs prepared according to the foregoing scheme, which are almost of no value for dyeing wool, are eminently suitable for dyeing leather. The dyestulfs belonging to this class are particularly distinguished by the beautiful tints they give on leather and they are therefore of great value in the art of leather dyeing. Moreover they enable the leather-dyers to obtain deep and Y full brown tints on leather by means of a single dyestufi' and thus to abandon the use of dyestuff mixtures hitherto'required for obtaining the said tints, which mixtures were apt to cause difliculties in the dyeing process. The dyestuffs belonging to the said type also possess excellent covering and levelling properties so much so that not only the grain of the leather but also the defective spots on it are dyed even tints of even depth. Such even dyeings on leather could not be obtained by the hitherto used dyestulf mixtures, because the various components of such mixtures are apt to give on the defective spots a tint which differs from that of the grain.

The fastness of the dyeings obtainable on leather by the dyestuffs in question entirely satisfy the requirements to be made in regard to dyeings on leather.

The method of dyeing with the dyestuffs of the above defined composition is the same used in dyeing with acid azo tion has been continued for 10 minutes, there are slowly added 200 cc. of formic acid of strength diluted with 2 litres of water, and the operation is continued for another 20 minutes. Thereupon there is added a fat as usual.

In the same manner maybe dyed barktanned sheepskin-leather and kid-leather with the only exception that in these cases the addition of a fat may be omitted.

Instead of the dyestufi indicated in the foregoing example there may be used in the same manner for dyeing the leather the folture as aforesaid-- resorcinol naphthionic acid picramic acid technical mixture as aforesaid-aresorcinole-picramio acid.

I claim:

1. The process of dyeing leather in full brown shades of even depth with acid azo dyestuffs, which comprises using for the dyeing process dyestuffs formed according to the scheme:

I II III IV amino-mon-su!ionatcd aminonaphthol sulfonic wid -amine rcsorcinol wherein I and IV each stand for a diazotizable aromatic amine, aminohydroxyor amino-azo compound or a substitution product thereof, II stands for non-sulfonated resorcinol or a substitution product thereof, and III stands for an aminonaphthol monoor disulfonic acid.

2. The process of dyeing leather in full brown shades of even depth with acid azo dyestufi's, which comprises using for the dyeing process dyestuffs formedaccording to the scheme:

I II III IV R-NHznon-sulfonntedinminonaphthol s u 110 111 c -emine resorcinol acid wherein R in I stands for an aromatic nucleus which may contain an NO group, II stands for non-sulfonated resorcinol or a substitution product thereof, III stands for an aminonaphthol monoor disulfonic acid, IV stands for a diazotizable aromatic amino, aminohydroxyor amino-azo compound or a substitution product thereof.

3. The process of dyeing leather in full brown shades of even depth with acid azo dyestuffs, which comprises using for the dyeing process dyestuiis formed according to the scheme:

p-nitroaniline+resorcino1--1-amino-8nnphthoi-3.6-di+--axhi he sulionic acid wherein IV stands for a diazotizable aromatic amine, aminohydroxy or amino-azo compound or a substitution product thereof.

4. The process of dyeing leather in full brown shades of even depth with acid azo dyestuiis, which comprises using for the dyeing process a 'dyestuii formed according to the scheme:

p-nitroanilineresorcinol1-amino-8-nupthol-3.6--picmmie disulfonic acid acid In testimony whereof, I aflix my signature.

BARTHOLOMAUS VOSSEN.

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