CH685251A5 - A process for dyeing leather. - Google Patents

Description

5

10th

15

20th

25th

30th

35

40

45

50

55

CH 685 251 A5

description

The present invention relates to a method for dyeing leather with anionic dyes and to the leather dyed by the method.

Processes for dyeing leather with anionic dyes are already known and are also used with great success in practice. The dyes are usually used in the form of solid or liquid commercial forms which contain more or less large amounts of aicali halide which has been added as a coupage to adjust a certain color strength or is present due to the production process. As a result, the dye liquors also contain aicali halide.

It has now been found that, surprisingly, the dyeability of the dyes is considerably greater when dyeing leather with special anionic dyes if the dyeing liquor contains little or no aicali halide.

The invention thus relates to a process for dyeing leather with anionic dyes, characterized in that an aqueous solution is used for dyeing, containing a polyazo dye with at least 2 sulfo groups and less than 1.5 wt .-%, based on the weight of the Dye, aicali halide.

A preferred embodiment of the method according to the invention consists in using an aqueous solution for dyeing which contains a dye of the formula

A the rest of an aromatic diazo component,

B the rest of a coupling component,

X OH or NH2,

n is 1 or 2 and m is 0, 1 or 2.

The diazo residue A leads e.g. from a heterocyclic or carbocyclic aromatic amine, preferably from 1- or 2-naphthylamine or aminobenzene, it being possible for the aromatic amines mentioned to be further substituted by one or more identical or different radicals.

Suitable substituents on the phenyl or naphthyl radical A are e.g. Ci-C4-alkyl, which here and further generally comprises methyl, ethyl, n- or isopropyl or n-, iso-, sec- or tert-butyl; C1-C4-alkoxy, which generally means methoxy, ethoxy, n- or iso-propoxy or n-, iso-, sec- or tert-butoxy; Halogen, e.g. Fluorine, bromine and especially chlorine; Trifluoromethyl; Ci-C4-AlkylsulfonyI, especially methyl- or ethylsulfonyl; Sulfamoyl; N-mono- or N, N-di-Ci-C4-alkylsulfamoyl; Carbamoyl; N-mono- or N, N-di-Ci-C4-alkylcarbamoyl, sulfo; Nitro; Cyano; Carboxy; Phenoxy; CHIVAIka-noylamino, especially acetylamino or propionylamino; Benzoylamino; Ci-C4-alkoxycarbonyl, e.g. Methoxy or ethoxycarbonyl.

Preferred diazo components are compounds of the formula in which R 1 and R 2 are each, independently of one another, hydrogen, C 1 -C 4 -alkyl, C 1 -C 4 -alkoxy, halogen, nitro, trifluoromethyl, C 1 -C 4 -alkylsulfonyl, acetylamino, hydroxyacetylamino, propionylamino, sulfamoyl, carbamoyl , Cyano, carboxy or phenoxy mean.

If the radical Ri or R2 is Ci-C4-alkylsulfonyl, it is e.g. ethylsulfonyl and especially methylsulfonyl.

Preferred meanings of R 1 and R 2 are independently hydrogen, methyl, ethyl, methoxy, ethoxy, chlorine, nitro, trifluoromethyl, methylsulfonyl, ethylsulfonyl, sulfamoyl, carbamoyl, cyano, acetylamino and phenoxy. R 1 and R 2 independently of one another are particularly preferably hydrogen, methyl, methoxy, nitro or chlorine.

Examples of preferred compounds of the formula (2) are: aniline, 2-, 3- or 4-methylaniline, 2-, 3- or 4-methoxyaniline, 2-, 3- or 4-chloroaniline, 2-, 3- or 4 -Nitroaniline, 2-chloro-4-nitroaniline, 2-methyl! -4-nitroaniline, 2,5-dichloroaniline, 2,5-dimethylaniline, 2,5-dimethoxyaniline or 2-methoxy-5-methylaniline.

X

(S03H) n

(1)

(2),

2nd

5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

CH 685 251 A5

The preferred meaning of X is OH and it is also preferred that the group X is not on the same ring as the NH2 group.

B denotes the rest of a coupling component, in particular a coupling component from the benzene or naphthalene series. B is preferably a radical of the formula in which R3 is hydroxy, amino, N-mono- or N, N-di-Ci-C4-alkylamino, phenylamino or 0-, m- or p-methylphenylamino and R4 and R5 independently of one another each have the meaning of R3 or represent hydrogen, benzoylamino, Ci-C4-alkanoylamino, carboxymethylamino, Ci-C4-alkyl, Ci-C4-alkoxy, phenoxy, carboxy, halogen, nitro or sulfo.

R3 is N-mono- or N, N-di-Ci-C4-alkylamino e.g. for methyl, ethyl, n- or iso-propyl- or n-, iso-, sec- or tert-butylamino or N, N-dimethyl-, N, N-diethyl-, N, N-di- n- or -iso-propyl- or N, N-di-n-, -iso-, -sec.- or -tert.-butylamino and preferably for N-methylamino, N-ethylamino, N, N-dimethylamino or N , N-diethylamino.

Preferred meanings of R3 are hydroxy, amino, N-methyl- and N-ethylamino, N, N-dimethyl- and N, N-diethylamino and phenylamino.

R3 particularly preferably represents hydroxy or amino.

R4 and / or R5, as well as the variables below as C 1 -C 4 -alkyl, are generally methyl, ethyl, n- or iso-propyl or n-, iso-, sec- or tert-butyl .

If R4 and / or R5 or the following variables stand for Ci-C4-alkoxy, this generally includes methoxy, ethoxy, n- or iso-propoxy or n-, iso-, sec- or tert-butoxy.

R4 and / or R5 as halogen are generally as follows, e.g. fluorine, bromine and especially chlorine.

R4 and / or R5 with the meaning Ci-C4-alkanoylamino are e.g. propionylamino, hydroxyacetylamino and especially acetylamino.

Sulfo generally encompasses the free acid form (-SO3H) as well as the salt form, alkali metal salts (Li, Na, K) or ammonium salts being particularly suitable.

R4 and R5 independently of one another preferably represent hydrogen, sulfo, acetylamino, methyl, ethyl, methoxy, ethoxy, chlorine, carboxy, hydroxy, amino, N-methyl- or N-ethylamino, N, N-dimethyl- or N, N- Diethylamino or phenylamino and particularly preferably for hydrogen, amino, hydroxy, methyl, methoxy, phenylamino or N, N-dimethyl- or N, N-diethylamino.

Compounds of the formula (3) are preferably used in which R3 is hydroxyl, amino, N-methyl- or N-ethylamino, N, N-dimethyl- or N, N-diethylamino or phenylamino and R4 and R5 are each independently of the other hydrogen Acetylamino, methyl, ethyl, methoxy, ethoxy, chlorine, carboxy, hydroxy, amino, N-methyl- or N-ethylamino, N, N-dimethyl- or N, N-diethylamino or phenylamino.

Examples of suitable compounds of the formula (3) are: phenol, 4-methylphenol, 1,3-dihydroxybenzene (resorcinol), 3-aminophenol, 1,3-phenylenediamine, 3-N, N-diethylaminophenol, 3-phenylaminophenol, 2,5-dimethylaniline, 2-methoxy-5-methylaniline, salicylic acid, 2- or 3-methylaniline, 2-methoxyaniline, 1,3-diamino-4-methylbenzene, 1,3-diamino-4-chlorobenzene and 1,3 -Diamino-4-methoxybenzene.

Compounds of the formula in which R3 'is amino or hydroxyl, R4' amino, hydroxyl, methyl, methoxy, phenylamino or N, N-dimethyl- or N, N-diethylamino and R5 'are particularly preferably hydrogen, methyl or methoxy are used.

A particularly preferred embodiment of the present invention relates to the use of 3-aminophenol, resorcinol or 1,3-phenylenediamine as the coupling component.

In the dyes of the formula (1), n is preferably 2 and m is preferably 1.

The dyes of the formula (1) are known or can be prepared in a known manner

(3),

(3a),

3rd

5

10th

15

20th

25th

30th

35

40

45

50

55

CH 685 251 A5

the. The use of dyes of the formula (1) which are described in DE-A 4 124 437 is particularly preferred.

The dyes of the formula (1) prepared in the customary manner normally contain about 5 to 30% by weight of aicali halide, based on the weight of the dye. This aicali halide is formed in the synthesis of the dye and / or added to the dye solution obtained for the separation of the dye. In addition, the solid or liquid commercial form of the dye is often adjusted to the desired color strength by adding aicali halide.

In contrast, in the dyeing process according to the invention, an aqueous solution containing a dye with less than 1.5% by weight, based on the weight of the dye, of aicali halide is used.

The dyes which are commercially available or produced in the customary manner must therefore be largely freed from the aicali halide before they are used in the dyeing process according to the invention. This is done in a manner known per se, for example by reverse osmosis, ultrafiltration or dialysis. Such desalination processes are known, e.g. from EP-A 0 059 782. Also known are the membranes used in these processes, e.g. from EP-A 0 061 424.

The process conditions for this desalination are chosen so that dye solutions are obtained which contain less than 1.5% by weight, based on the weight of the dye, of aicali halide. Dye salts and salts with higher molecular weight cations and / or anions are not or only slightly removed.

In this application, aicali halide is understood to mean lithium, sodium and potassium fluoride, chloride, bromide and iodide.

After desalting, the dye is in the form of an aqueous solution which, if desired, is concentrated or e.g. by spray drying, can be evaporated to dryness.

A preferred embodiment of the dyeing process according to the invention is characterized in that an aqueous solution containing a polyazo dye of the formula (1) and less than 1.0% by weight, based on the weight of the dye, of aicali halide is used for the dyeing.

In the dyeing process according to the invention, the dyes are preferably used as aqueous dye preparations. These preparations preferably contain 5 to 40% by weight of dye, 65 to 95% by weight of water, 0 to 20% by weight of further additives and less than 1.5% by weight, based on the weight of the dye, of aicali halide .

Dye preparations used with preference contain 10 to 25% by weight of dye, 70 to 90% by weight of water, 0 to 20% by weight of further additives and less than 1.0% by weight, based on the weight of the dye, of aicali halide .

As further additives, the dye preparations can e.g. contain surface-active substances, buffer substances, foam-suppressing aids, antifreezing agents and substances that inhibit fungal and / or bacterial growth.

The amounts in which the dyes are used in the dye baths can vary within wide limits depending on the desired depth of color. In general, amounts of dye of 0.1 to 10, preferably 0.5 to 4% by weight, based on the weight of the leather to be dyed, are advantageous.

In addition to water and the dyes, the dye liquor can also contain other additives, e.g. Acids or bases for setting the desired pH value, as well as auxiliaries such as Wetting agents, greasing agents, color-deepening aids, leveling agents, and / or anti-foaming agents.

The process according to the invention has the great advantage that less dye is required to achieve a certain depth of color than when using dyeing liquors which contain larger amounts of alkali metal halides, since the dyestuff capacity is greater.

The method according to the invention is not only suitable for a certain type of leather, but can also be applied to the different types of leather, for example chrome leather, retanned leather or suede from goat, cow or pig.

The dyeing is preferably carried out by the exhaust process, e.g. at a liquor ratio of 1: 1.5 to 1:20, preferably 1: 2 to 1:10, and at temperatures of 20 to 100 ° C, preferably 30 to 60 ° C. If desired or necessary, the leather can be subjected to a pretreatment, for example neutralization or rolling.

The dyeing time varies depending on the type of leather and the desired depth of color, but is generally between 30 and 180 minutes. After the dyeing, the leather is rinsed and finished as usual.

The process according to the invention gives leather dyeings in the same shades and fastness properties as when dyeing with dye liquors which are richer in alkali halide.

The following examples illustrate the invention without restricting it. Parts mean parts by weight and percentages percentages by weight. The dyes are used in commercially available powder form; the indicated amounts of dye refer to the coupé 100% dye commercial form.

4th

5

10th

15

20th

25th

30th

35

40

45

50

55

60

65

CH 685 251 A5

Example 1:

1.25 kg press cake of the raw dye of the formula

^^ - N = N

oh nh2

ho3s with a dry content of 32% are slurried with 3 kg of water (factory water). The suspension obtained is adjusted to a pH of 7 to 7.5 with 50% sodium hydroxide solution. A low-viscosity solution with a dry dye content of 8.0% and a sodium chloride content of 1.3% is obtained. This solution is desalinated in a laboratory reverse osmosis system under the following conditions: MPS membrane, approx. 40 ° C, feed: 12 l / h, 25 bar, flux 1289 l / m2d (average). After 4.5 hours, 1.9 kg of a solution with a dye content of 18.0% by weight and a sodium chloride content of 0.05% by weight (0.9% by weight, based on the dye) are obtained. This desalted and concentrated solution is adjusted to a dye content of 15% after filtration through a 10 m sieve with water.

100 parts of chrome-colored suede clothing (dry weight) are rolled on at 50 ° C in a solution of 1000 parts of water and 2 parts of 24% ammonia for 60 minutes. This is followed by a 15-minute washing process in 1000 parts of water at 50 ° C.

After these preparatory operations, the leather is dyed in a float of 1000 parts of water, 2 parts of 24% ammonia and 13.33 parts of the dye solution described above at 50 ° C.

After a dyeing time of 60 minutes, the mixture is acidified with 4 parts of 85% formic acid and then dyeing is continued for 20 minutes.

The dyed leather is finished after treatment in a fresh bath with 1000 parts of water, 2.5 parts of a condensation product of formaldehyde, dicyandiamide, ammonium chloride and ethylenediamine and 0.5 part of 85% formic acid for 45 minutes at 50 ° C. The leather obtained is dyed black. It is characterized by good fastness properties and good opacity.

100 parts of chrome-tanned cowhide with a fold thickness of 1.4 mm are drummed in a fleet consisting of 200 parts of water, 1 part of sodium bicarbonate and 1 part of sodium formate for 45 minutes at 30 ° C. and then washed twice with 300 parts of water at the same temperature.

The leather neutralized in this way is then dyed at 50 ° C. in a liquor composed of 1000 parts of water, 2 parts of 24% ammonia and 15 parts of the dye solution described in Example 1. After 30 minutes, 3 parts of a synthetic fatliquor (mixture of alkylbenzenes, aliphatic hydrocarbons, alkanesulfonic acids and surfactants) are added to the dyeing liquor, and after a further 30 minutes 0.5 parts of 85% formic acid, diluted with 5 parts of water, are added. Thereafter, the treatment is continued at 50 ° C. for 20 minutes.

After rinsing well in cold water and finishing in the usual way, the result is an empty black color with excellent fastness properties, in particular good diffusion fastness to soft PVC. The color matches the color obtained in Example 1.

In order to obtain the same color depth with a solution of the same dye, but which contains 1.3% by weight (7.2% by weight, based on the dye) of sodium chloride, about a third more dye must be used , if you dye under otherwise identical dyeing conditions.

Examples 3 to 8:

If one works as described in Example 2, but instead of the dye used there, the same parts of the dyes listed in the following table are used, black leather is also obtained.

Example 2:

5

5

10th

15

20th

25th

30th

35

40

45

50

55

CH 685 251 A5

E.g.

dye

Ç ^ -N = N C1 HOoS

OH NH2

n = n "~ c = ^ ~ nh-O N = N ~ çy ~ ° H

SOoH S0 ^ H NH,

E.g.

dye

CH3

r-1 OH NH2

= N

^^ - N = N N = N - <^> - NH - ^^ - N.N-Q- OH

H03S SO3H s03H

nho

CH3

, —L OH NH2

° 2N - ^ 3 ~ N = N N = N ~ C = ^ ~ NH-O N = N ~ ^ 3 ~ 0E

HOqS SO, H S03H

NHo

OH NH.

NH-O- n = n-Q-

HO, S cclw SO, H HO

OH

H03S SO, H

OH NH2

<Q-N = N N = NH ^ - NH-HQ- N = N- <Ç> NH2

H03S ^ 5 ^ 5 ^ S03H s03h nh,

<Q-n.N

OH NH2

HO, S

n = n ~ C3 ~ ° ~ {C3 ~ n = n ^ P ~ 0H

S03H NH °

Claims (1)

Claims 1. A process for dyeing leather with anionic dyes, characterized in that an aqueous solution is used for dyeing, comprising a polyazo dye with at least 2 sulfon groups and less than 1.5% by weight, based on the weight of the dye, Aicali halide. 6 5 10th 15 20th 25th 30th 35 40 45 50 55 60 65 CH 685 251 A5 2. The method according to claim 1, characterized in that one uses an aqueous solution for dyeing, which is a dye of the formula / \ NH2 A "N = N Qj- N = N (S03H) n where A the rest of an aromatic diazo component, B the rest of a coupling component, X OH or NH2, n denotes 1 or 2 and m denotes 0, 1 or 2. 3. The method according to any one of claims 1 or 2, characterized in that a dye of the formula (1) is used, in which the diazo radical A is derived from 1- or 2-naphthylamine or aminobenzene, the aromatic amines mentioned by a or several identical or different radicals can be further substituted. 4. The method according to any one of claims 1 to 3, characterized in that one uses a dye of the formula (1) in which the diazo radical A is an amine of the formula "C3" nh ~ C3 • N = N-B (S03H) m (1) where Ri and R2 are each independently hydrogen, Gi-C4-alkyl, Ci-C4-alkoxy, halogen, nitro, trifluoromethyl, Ci-C4-alkylsulfonyl, acetylamino, hydroxyacetylamino, propionylamino, sulfamoyl, carbamoyl, cyano, carboxy or phenoxy mean. 5. The method according to claim 4, characterized in that Ri and R2 independently of one another are hydrogen, methyl, ethyl, methoxy, ethoxy, chlorine, nitro, trifluoromethyl, methylsulfonyl, ethylsulfonyl, sulfamoyl, carbamoyl, cyano, acetylamino or phenoxy. 6. The method according to claim 5, characterized in that R 1 and R 2 each independently represent hydrogen, methyl, methoxy, nitro or chlorine. 7. The method according to any one of claims 1 to 3, characterized in that the diazo radical A is aniline, 2-, 3- or 4-methylaniline, 2-, 3- or 4-methoxyaniline, 2-, 3 or 4-chloroaniline, 2-, 3- or 4-nitroaniline, 2-chloro-4-nitroaniline, 2-methyl-4-nitroaniline, 2,5-dichloroaniline, 2,5-dimethylaniline, 2,5-dimethoxyaniline or 2-methoxy 5-methylaniline is derived. 8. The method according to any one of claims 1 to 7, characterized in that X is OH. 9. The method according to any one of claims 1 to 8, characterized in that X is not on the same ring as the NH2 group. 10. The method according to any one of claims 1 to 9, characterized in that B is a radical of the formula in which R3 is hydroxy, amino, N-mono- or N, N-di-Ci-C4-alkylamino, phenylamino or 0-, m- or p-methylphenylamino and R4 and R5 independently of one another each have the meaning of R3 or for hydrogen, benzoylamino, Ci-C4-alkanoylamino, carboxymethylamino, Ci-C4-alkyl, Ci-C4-alkoxy, phenoxy, carboxy, halogen , Nitro or sulfo. 7