DE2856883A1 - Dulling the colour of anionic dyes on leather - by treatment with nitro-4-amino-di:phenylamine sulphonate salt - Google Patents

Abstract

Method for producing dull cover tones on leather or hides from aq. baths of anionic dyes by the exhaust method, comprises treating the material before, during and after dyeing with alkali salts of nitro-p-amino-diphenylamine sulphonic acids (I) and their alkyl derivs. (I) are generally applicable dulling agents (contrast black dyes which can only be used with dark colours), have good resistance to light and compatibility with dyes. They give an even effect without modifying the feel, elasticity or softness of the material, and their own colour is similar to that of Cr-tanned leather.

Description

Process for tarnishing leather dyeings

The present invention relates to a method for setting cloudy, muted shades on leather and fur skins from aqueous dye liquors of anionic Dyes using the exhaust method.

The majority of all leathers that are not dyed black make covered leather and clouded nuances of color. For these muted nuances, the customary colors are used But leather dyes are generally too brilliant; Colorations based on those mentioned Products must therefore be tarnished by suitable means. In this relationship has primarily been an addition of black dyes to the respective dye baths offered. In the case of light and medium shades, however, this causes blackening considerable difficulties, because you only get limited, narrow black as Can use opacifiers, otherwise the colorful nuances slide off to black and achromatic tones arise.

Thus, for this reason, in many cases up to now one has been forced to such clouding of medium and pastel-colored tones without the use of black Work out mixtures of complementary colors in numerous preliminary tests.

To set cloudy, muted hues on leather and fur skins, when dyeing from aqueous liquors, the principles of the trichromatic dyeing method based on the three basic colors blue, red and yellow (type dyeings) or those dyes whose nuances are easy to apply are used the diagram of the pattern arrangement based on this system can be arranged in a triangular shape. QU * 6th : Slate --- "e black center - 6 ' Bordo 4 orange - 5cherlach red It is known that the cloudiness of the color nuance is greater, the closer the percentage composition of the dye mixture approaches the center of the mixing triangle, which generally represents the achromatic and maximally clouding black center. When making nuances on this basis, one must therefore carefully avoid getting close to the center of the triangle with the concentration ratios of the mixture components.

As a disadvantage of setting one with the help of the mixing triangle produced muted and cloudy color nuances you usually have to make significant concessions accept the desired solid color so as not to be too close to the blackening / clouding center approach, with achromatic nuances coming to the fore.

The creation of muted, washed-out-looking or cloudy color tones therefore requires a lot more experience of nuances than with brilliant nuances and leads to discoloration in very many cases.

A neutral and universally applicable tool for setting is duller shades of color - apart from the soluble black dyes, which are only used in a sufficiently effective concentration for very dark shades can be - but so far unknown. In terms of its usefulness for the Such a product has a certain number of conditions to be fulfilled: Such an aid must substantively apply to the leather from dye baths pull on and still dye very deeply into the leather interior, good lightfastness be and be with anionic dyes of the most diverse classes as well as in the same direction Let the loaded tools combine satisfactorily.

In addition, one must pay particular attention to the leveling power of this product make high demands.

In the case of its application to non-dyed leather, the inherent color should of the opacifying agent close to the greenish inherent color of chromium-III salts tanned leathers and as close as possible to the natural color of a vegetable tanned one Leather lying.

After all, the aid is supposed to be the handle, the softness and elasticity of the goods in contrast to treatment with vegetable tanning agents but not be affected.

The suitability criteria set out above result in The object of the present invention is to simplify the nuance and opacification of leather dyes that are too brilliant by developing a neutral and uni- versell usable anionic, water-soluble opacifiers.

It has now been found that amphoteric compounds of the diphenylamine series with polar amino or sulfonic acid groups on the one hand and nonpolar nitro and optionally alkyl groups on the other hand meet all the properties of a neutral opacifier. These are generally the alkali salts of nitro-p-aminodiphenylamine-sulfonic acids or their alkyl derivatives, in particular compounds of the general formula where X is a hydrogen atom or a lower alkyl radical, preferably methyl.

The task defined above is thus achieved according to the invention solved that the goods before, during or after the dyeing operation with alkali salts treated by nitro-paminodiphenylamine-sulfonic acids or their alkyl derivatives.

The amphoteric nitro-p-aminodiphenylamine-sulfonic acids used according to the invention fulfill the above requirements as opacifiers much better than the previously used black painters. Those treated with these products alone, not dyed leather result in olive or. khaki nuances that are excellent Levelness, good lightfastness and a homozygous coloration of the entire leather cross-section demonstrate.

Because of their excellent penetration and leveling ability Nitro-p-amino-diphenylamine-sulfonic acids can be used as a uniform through-dye can be used with the typical leather dyes. Such additives too others Dyes tarnish the brilliance of these dyes on leather and fur skins to a greater extent Dimensions without changing the full color significantly. They mediate - in contrast to blackening - even in the case of high concentrations no achromaticity of the stains produced in this way.

Because the free nitro-p-amino-diphenylamine-sulfonic acids are not soluble in water they must be dissolved in an alkaline solution before use. The opacifier can can be applied both before and after staining. The optimal effect achieved if it is added directly to the aqueous dye liquor together with the dyes and, as usual, exhausts the dyebaths with acid.

Example Commercially available chrome cooked, intermediate dried and pre-ground Split suede with a leather thickness of 1.9 mm is used as usual in rotating Dyeing barrel with 600% (based on the weight of the dry leather) water at 550C broken up and with 2.0% one of the dyes or mixtures given below of which dyed (based on the weight of the goods) for 30 minutes at the stated temperature, then Acidified with 1.0% (of the weight of the goods) formic acid as usual and then 15 minutes walked on for a long time.

At the same time, the same coloration with the addition of 0.3% (from Weight of goods) 4-nitro-4'-aminodiphenylamine-6-sulfonic acid (Na salt) carried out.

There is a contrast on all leathers treated with the opacifier the original color of the parallel leathers dyed without the addition of opacifying agents heavily and evenly tarnished. This cloudiness extends so far into the leather interior into how the original brilliant dye was absorbed (approx. 0.3-0.4 mm from both sides), and shows no turbidity gradient with increasing layer depth.

Because of the uniform, deep haze, the leathers could do very well can be re-ground without causing different turbidity / resp. Grind out brilliant zones.

The shade of the original color was determined by the addition of the opacifier not changed, only the brilliant Acid Orange 7 dye appears Trace to brown-orange pressed.

The undyed leather sample treated with the opacifier alone shows opposite the greenish chromium-III-intrinsic color of the leather a leather cross-section that is uniform both on the surface and in the entire 1.8 mm thick yellowish green khaki color, retanned with vegetable tanning agents Chrome leather resembles, but the fine velor handle of the velor fiber is not like this undesirably hardened.

Commercially available dyes have been used in the dyeing process described above Products used; Examples of this are listed in the following table: Tabel C.I. Generic name C.I. Constitution Number From the uniform, brilliant category Coloring leather dyes Acid Yellow 56 24 825 Direct Orange 17 19 160 Acid Red 379 Acid Red 199 23 295 Acid Brown 106 Acid Brown 104 Acid Blue 123 44 510 Acid Orange 7 15 510 Acid Red 44 16 250 From the brilliantly colored leather mix category Mixture of Acid Yellow 36 13 065 Direct Yellow 11 40 000 Acid Orange 7 15 510 Direct Orange 15 40 002 From the category of uniform, brilliant coloring wool dyes Acid Blue 205 Acid Violet 102 Acid Red 289 45 110 Direct Blue 199 From the category Uniform, brilliant coloring reactive dyes Reactive Green 14

Claims (2)

Claims: 1. Method for setting cloudy, muted color tones on leather and fur skins from aqueous dye liquors of anionic dyes according to the pull-out method, characterized in that the goods are before, during or after the tanning operation with alkali salts of nitro-p-aminodiphenylamine sulfone acids or their alkyl derivatives treated. 2. Use of the alkali salts of nitro-p-aminodiphenylamine sulfonic acids as opacifiers for setting cloudy, muted shades with anionic ones Dyes dyed leather and fur skins.