EP0792377A1

EP0792377A1 - Process for preparing leather and furs using polymer tanning agents

Info

Publication number: EP0792377A1
Application number: EP95937048A
Authority: EP
Inventors: Manfred Breth; Jürgen CARLE; Hermann Birkhofer; Michael Kneip
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 1994-11-15
Filing date: 1995-11-03
Publication date: 1997-09-03
Also published as: WO1996015276A1; DE4440846A1; JPH10508644A; AU3927395A

Abstract

The invention concerns the preparation of leather and furs by tanning without the use of plant, synthetic and mineral tanning agents and only with polymer tanning agents. Aldehydes or reactive carbonyl compounds can optionally be used in the pre-tanning stage.

Description

Process for the production of leather and furskin using polymer tanning agents

description

The present invention relates to an improved process for the production of leather and fur skins using polymer tanning agents.

The mineral tanning that has so far been common worldwide, in particular chrome tanning, which by far has the largest share in terms of quantity, is coming under fire for ecological reasons. The tannery wastewater has to be freed of chromium salts, shavings and cut leather remnants have to be disposed of in hazardous waste landfills.

For some years now, attempts have been made to introduce alternative tanning to the market. As a rule, it is assumed that the bare ends are stabilized with aldehydes such as formaldehyde or glyoxal and are then brought to a certain thickness after folding. The pelts are then tanned with vegetable, synthetic or chromium-free mineral materials, greased with natural or synthetic greasing agents and dyed with leather dyes.

In addition to ecological problems with heavy metal compounds, there are also environmental problems with the other tanning agents mentioned, because also vegetable tanning agents, which often contain toxicologically questionable phenol derivatives, and synthetic tanning agents ("Syntane"), which mostly contain condensation products from toxic and irritating starting materials such as phenols or formaldehyde are under fire. In addition, wastewater problems, the contamination with organic matter, generally occur with such tanning processes. (COD value) is much too high due to poor tanning liquor consumption. Another disadvantage is that the leather produced in this way is unsatisfactory in terms of its properties such as light fastness or heat yellowing stability.

It was therefore an object of the present invention to provide an improved process for the production of leather and fur, which is simple and inexpensive, does not need the ecologically disadvantageous tanning agents mentioned and nevertheless delivers products with high quality and excellent properties. Accordingly, a process has been found for the production of leather and fur, which is characterized in that tanning is carried out in the absence of vegetable, synthetic and mineral tanning agents and only polymeric tanning agents are used for tanning, and aldehydes or reactive carbonyl compounds are used for pretanning.

In practice, the process according to the invention is usually carried out by pretanning using aldehydes or reactive carbonyl compounds, polymer tanning agents or a mixture thereof, and tanning using one or more polymer tanning agents or a mixture of polymer tanning agents and fatliquoring agents.

Pretanning essentially serves to stabilize the

Bare that only become foldable. The subsequent tanning process represents the actual tanning step.

When tanning, it is often advisable to grease the leather at the same time and to use appropriate greasing agents. Polymer tanning agents often have more or less greasy properties at the same time, which in some cases can be made the dominant property by modification in the tanning agent formulation, for example by adding emulsifiers. In principle, however, all customary non-tanning fatliquoring agents can also be used in the process of tanning.

Particularly suitable as aldehydes or reactive carbonyl compounds in the pretanning step

(a) aliphatic dialdehydes with 2 to 8 carbon atoms,

(b) aromatic dialdehydes having 8 to 14 carbon atoms,

(c) araliphatic dialdehydes with 9 to 16 carbon atoms,

(d) aliphatic monobasic aldehyde carboxylic acids with 2 to 8 carbon atoms,

(e) aliphatic mono- or dibasic ketocarboxylic acids with 3 to 10 carbon atoms or

(f) formaldehyde or mixtures of the aldehydes (a) to (f), the said aldehydes also in the form of their acetals with aliphatic mono- or dihydric ci to cio alcohols which additionally with 1 to 50 mol of ethylene oxide or propylene oxide or a mixture thereof per hydroxyl group may have been implemented.

As aliphatic dialdehydes (a) there are in particular saturated structures, i.e. Structures without other reactive centers, such as double bonds or triple bonds, are suitable. However, the aliphatic chain can be interrupted by one or more non-adjacent oxygen atoms. In particular, α, ω-dialdehydes such as glyoxal, malondialdehyde, succindialdehyde, glutardialdehyde, 3-oxaglutardialdehyde, adipindialdehyde, pimeline dialdehyde and the dialdehyde derived from suberic acid are suitable.

Aromatic dialdehydes (b) include, for example, terephthalaldehyde, naphthalene dialdehydes or 2,5-dimethyl terephthalaldehyde.

Araliphatic dialdehydes (c) include, for example p-phenylene-diacetaldehyde, p-phenylene-di-3-propionaldehyde and p-phenylene-di-4-butyraldehyde. Compounds with an aromatic and an aliphatic aldehyde function should also be mentioned here, e.g. p-formylphenylacetaldehyde.

In the case of the aldehyde carboxylic acids (d), ω-aldehyde carboxylic acids such as malonic acid monoaldehyde, succinic acid monoaldehyde, glutaric acid monoaldehyde, adipic acid monoaldehyde, pimelic acid monoaldehyde or kor acid monoaldehyde are particularly suitable. Glyoxylic acid is of particular interest here.

Examples of ketocarboxylic acids (e) are pyruvic acid, levulinic acid, mesoxalic acid, α-oxoglutaric acid and oxaloacetic acid. Here, α-ketocarboxylic acids are preferred.

If the dialdehydes (a) to (c) are in the form of acetals, both aldehyde functions are usually acetalized. However, compounds with only one acetalized aldehyde function can be used in the process according to the invention.

For the acetalization, especially alkali to C ₃ -alkanols such as methanol, ethanol, n-propanol or isopropanol and alkanediols, which are cyclic with the aldehyde function, can be used as the alcohols

Form acetal, for example 1,2-ethylene glycol or 1,3-propylene glycol, can be used. Furthermore, those used for acetalization used alcohols with 1 to 50 mol, in particular 2 to 30 mol, especially 3 to 15 mol ethylene oxide or propylene oxide or a mixture thereof per hydroxyl group, examples of which are correspondingly ethoxylated or propoxylated methanol, ethanol, n-propanol, n-butanol, ethylene glycol or propylene glycols.

Formaldehyde (f) is just as good as the compounds (a) to (e) with regard to the stabilizing effect on the nakedness, but is often avoided for ecological reasons.

Of the aldehydes or reactive carbonyl compounds mentioned, aliphatic dialdehydes (a) having 2 to 5 carbon atoms are particularly preferred, in particular glyoxal, glutardialdehyde and 3-oxaglutaraldehyde.

Suitable polymeric tanning agents for the pretanning step as well as for the tanning step of the process according to the invention are suitably effective homo-, co-, ter- or graft polymers. As a rule, these are polymers containing carboxyl groups. The following groups of substances are particularly suitable:

A) homopolymers of acrylic acid and methacrylic acid with a molecular weight of 1000 to 200000, in particular 2000 to 100000 (corresponding to K values of 12 to 150, in particular 15 to 120); these polycarboxylates can be used in the free acid form or as salts, for example alkali metal or ammonium salts;

B) Copolymers of acrylic and methacrylic acid with acrylic or methacrylic acid Ci to C o-alkyl or -C ₂ - to C ₃ o-alkenyl esters in a weight ratio of 90:10 to 10:90 a molar mass from 1000 to 100000, for example acrylic or methacrylic acid copolymers with Ci to C ₂ o-alkyl (meth) acrylates such as methyl, ethyl, n-propyl, isopropyl, n-butyl, n-hexyl -, n-octyl or 2-ethylhexyl (meth) acrylate; such copolymers are described for example in EP-B 498 634;

C) copolymers and terpolymers of C ₂ - to C -01efinen (CD with acrylic or methacrylic acid (C2) or with acrylic or methacrylic acid-Ci to C ₃ o-alkyl or -C ₂ - to C ₃ o-alkenyl esters, preferably Ci to C ₂ o-al yl (meth) acrylates, (C3) or with a mixture of (C2) and (C3) in a weight ratio of 95: 5 to 5:95, in particular 95 : 5 to 70:30, for copolymers or of (CD: [(C2) + C3)] = 95: 5 to 5:95, in particular 95: 5 to 70:30 for terpolymers, where (C2) and ( C3) can be in a weight ratio of 99.5: 0.5 to 0.5: 99.5, a molecular weight of 2,000 to 100,000, for example acrylic or methacrylic acid / ethylene copolymers, acrylic or methacrylic acid / propylene copolymers, acrylic or methacrylic acid / isobutene copolymers, acrylic or methacrylic acid / butadiene copolymers, acrylic or methacrylic acid-ethylene-Ci to C _θ- alkyl (meth) acrylate copolymers or acrylic or meth-acrylic acid-propylene-Ci to Ce-alkyl (meth) acrylates;

D) terpolymers of acrylic or methacrylic acid, N- (3-di-Cι to C -alkylaminopropyl) acrylamide or methacrylamide and

Acrylonitrile or acrylamide with K values of 15 to 80, a carboxyl group content of 6 to 40% by weight and a number ratio of tertiary amino to carboxyl groups of 1:20 to 17:20; such polymers are described for example in EP-B 084 134;

E) Copolymers obtained by radical copolymerization of Cε to C o monoolefins with ethylenically unsaturated C to Cβ dicarboxylic acid anhydrides, e.g. Maleic anhydride (MA), obtainable in the manner of bulk polymerization at temperatures from 80 to 300 ° C. to copolymers with molar masses from 500 to 20,000, subsequent solvolysis of the anhydride groups of the copolymers and at least partial neutralization of the carboxyl groups formed during solvolysis in an aqueous medium with bases are; such polymers are described for example in DE-A 39 26 167;

F) Copolymers which are obtained by radical copolymerization of Cβ- to C o-alkyl vinyl ethers or hybrids of ζ- to C o-alkyl vinyl ethers and up to 50 mol% of Cε- to C o-mono-olefins with ethylenically unsaturated C - to Cβ- Dicarboxylic acid anhydrides, e.g. Maleic anhydride (MA), for copolymers with molecular weights of 500 to 20,000, subsequent solvolysis of the anhydride groups of the copolymers and at least partial neutralization of the carboxyl groups formed during solvolysis are obtainable in an aqueous medium with bases; such polymers are described for example in DE-A 39 26 168;

G) copolymers that

50 to 90% by weight of Cβ to C o-alkyl acrylates, Cβ to C o alkyl methacrylates, vinyl esters of Cβ to C ₄ o-carboxylic acids or mixtures thereof and 10 to 50% by weight of monoethylenically unsaturated C ₃ to C ₁₂ carboxylic acids, monoethylenically unsaturated dicarboxylic acid anhydrides, half esters or half amides of monoethylenically unsaturated C to C ₂ dicarboxylic acids, A ide of monoethylenically unsaturated C ₃ to C 1 ₂ -monocarboxylic acids or mixtures thereof

contain polymerized and have a molecular weight of 500 to 30,000, in at least partially neutralized form; such polymers are described for example in DE-A 39 31 039:

Aqueous solutions or aqueous dispersions of copolymers which are obtained by radical copolymerization of

40 to 60 mol% of Cζ to C ₄ o ~ monoolefins or Cζ to C o alkyl vinyl ethers or mixtures of C ₆ to C o alkyl vinyl ethers and up to 50 mol%, based on the total amount of this component, C _δ - to C o-monoolefins with

60 to 40 mol% of monoethylenically unsaturated C ₄ - to Cβ-dicarboxylic acid anhydrides

or by radical copolymerization of

50 to 90 wt .-% C ₆ - to C o -alkyl acrylates or methacrylates or vinyl esters of Cβ to C ₄ o-carboxylic acids or mixtures thereof

10 to 50% by weight of monoethylenically unsaturated C ₃ to C ₁₂ carboxylic acids, monoethylenically unsaturated C to C ₂ dicarboxylic acid anhydrides, half-esters or half amides of monoethylenically unsaturated C to C ₂ dicarboxylic acids, amides of monoethylenically unsaturated C ₃ - Up to Ci ₂ carboxylic acids or mixtures thereof

to copolymers with molecular weights of 500 to 30,000 are available, the carboxyl groups present in aqueous medium being at least partially neutralized and part of the carboxyl groups being amidated, with a content of 0.5 to 40% by weight, based on the Amount of copolymer, of emulsifiers; such polymer solutions or dispersions are described, for example, in German patent application P 44 02 029.5; Implementation products from

Homopolymers or copolymers based on monoethylenically unsaturated dicarboxylic acid anhydrides, obtainable by free radical polymerization of

30 to 100 mol% of one or more monoethylenically unsaturated dicarboxylic anhydrides having 4 to 10 carbon atoms,

- 0 to 70 mol% of one or more vinyl aromatics of the general formula I.

R ⁱ

in which R ¹ , R ² and R ^{3 are} hydrogen, methyl or ethyl and k is 1 or 2,

0 to 70 mol% of one or more vinyl esters of Ci- to Cβ-carboxylic acids,

0 to 50 mol% of one or more C2 to Cβ olefins and

0 to 30 mol% of one or more monoethylenically unsaturated C ₃ to Cs carboxylic acids,

wherein up to 10% by weight of further copolymerizable monomers can also be added to the monomer mixture mentioned, with

Amines of the general formula R ⁴ R ⁵ NH in which R ⁴ Wasser¬ material, Ci- _ß-C2 ₀ alkyl, C5-Cβ cycloalkyl or C 2 to C ⁵ hydroxyalkyl and R C - to C ₃ o- Alkyl, C _ß - to C ₃ o-alkenyl, Cβ- to Cβ-cycloalkyl or C2- to C ₄ -hydroxyalkyl, or alcohols of the general formula R ⁶ -0- (C _m H2 _m O) _p - ( C _n H2 _n O); -H, in the R ⁶ for Cχ ~ to C ₃ o-alkyl, C2- to C ₃ o-alkenyl, C5- to Cβ-cycloalkyl or in the case p + q> 0 for hydrogen is, m and n each represent a number from 2 to 4 and p and q each denote a number from 9 to 50, or mixtures of such amines and alcohols;

such reaction products are described for example in WO-A 93/17130; K) Graft polymers of vegetable and animal oils, obtainable by free-radically initiated polymerization

of a monomer or a mixture of monomers

20 to 100% by weight of monoethylenically unsaturated carboxylic acid and / or monoethylenically unsaturated sulfonic acids and / or monoethylenically unsaturated phosphonic acids, their anhydrides or their alkali metal, alkaline earth metal or ammonium salts,

0 to 80% by weight of other monoethylenically unsaturated monomers which can be copolymerized with the abovementioned monomers, and

0 to 5% by weight of at least double ethylenically non-conjugated unsaturated monomers

in the presence of

vegetable and / or animal oils

in the weight ratio of (80 to 1): (20 to 99);

such graft polymers are described for example in DE-A 42 24 456;

L) Water-soluble graft polymers of monosaccharides, oligosaccharides, polysaccharides and their derivatives, obtainable by free-radically initiated polymerization

of a monomer or a mixture of monomers

20 to 100% by weight of acrylic acid or methacrylic acid or a mixture thereof, the alkali metal, alkaline earth metal or ammonium salts thereof,

0 to 80% by weight of other monoethylenically unsaturated monomers which can be copolymerized with the above-mentioned monomers and

0 to 5% by weight of at least 2 ethylenically unsaturated, non-conjugated double bonds in the molecule having monomers

in the presence of Monosaccharides, oligosaccharides, polysaccharides, oxidatively, hydrolytically or enzymatically degraded polysaccharides, oxidized hydrolytically or oxidized enzymatically degraded polysaccharides, chemically modified mono-, oligo- or polysaccharides or mixtures of the compounds mentioned

in the weight ratio of (95 to 20): (5 to 80);

such graft polymers are described, for example, in DE-A 42 02 452;

M) Use of water-soluble or water-dispersible graft polymers of proteins, obtainable by radical-initiated polymerization

of a monomer or a mixture of monomers

20 to 100% by weight of acrylic acid or methacrylic acid or a mixture thereof or their alkali metal, alkaline earth metal or ammonium salts,

in the presence of

Proteins like bone glue

in the weight ratio of (95 to 10): (5 to 90);

such graft polymers are described, for example, in German patent application P 44 16 877.2;

N) Copolymers obtained by copolymerizing a first component selected from the series of ethylenically unsaturated dicarboxylic acid anhydrides, ethylenically unsaturated dicarboxylic acid esters and ethylenically unsaturated dicarboxylic acid amides or mixtures thereof, and a second component of the general formula II H ₂ C = C _{II (}

[X] - Y where X = (CH ₂ ) r 'r _> 2 and Y represents a carboxyl group or an OCOR ⁷ radical, a COOR ⁸ radical or a CONR ⁹ R ¹⁰ radical and Z represents hydrogen or a lower one is alkyl, wherein R ⁷ is a Cι-C ₂ ^_ o alkyl radical, wherein R ⁸ is a Cι-C ₃ -alkyl radical or an alkoxylation product thereof, wherein R ⁹ and R ¹⁰ is hydrogen or an alkyl radical (C ₁ to C ₂₀₎ represent and may be different;

such copolymers preferably have a molecular weight of 800 to 30,000;

typical examples of the first component are maleic anhydride and dibutyl maleate, typical examples of the second component are an undecenoic acid derivative or a

Undecenol derivative and alkyl vinyl ether with 8 to 20 carbon atoms, carboxylic acid vinyl ester with 8 to 20 carbon atoms and 1-alkenes with 8 to 30 carbon atoms, individually or as a mixture;

the copolymers mentioned are described, for example, in EP-A 567 842;

Polymers containing hydroxyl groups, composed of

- 95 to 0 wt .-% of monomers of formula III

R ₁₂ HC - C (Rn) - COOH III where Rn is hydrogen, methyl or a group -CH ₂ COOH

R _{12 represents} hydrogen, methyl, phenyl or a group

-COOH stand, provided that there are no more than two

Carboxyl groups are in the molecule, or on monomers of the formula III-A

where A is a radical HC = CH or a radical H ₂ C = C-CH ₂ and 0 to 90% by weight of hydroxyl-containing monomers of the formula IV

Rn 0

IV

CH ₂ = C - C - ORi

wherein

Ri ₃ for hydrogen or methyl and Rι for an alkyl radical or cycloalkyl radical with 1 to 12 carbon atoms substituted with at least one hydroxyl group, and

0 to 100% by weight of monomers of the formula V

V

CH ₂ = CH -0 CR ₁₅

wherein Rχ _{5 is} an alkyl radical having 1 to 2 carbon atoms and

0 to 80% by weight of monomers of the formula VI

Rl3

VI CH ₂ = C COORie in which R ₁ 3 represents hydrogen or methyl and Ri _{6 represents} an optionally cyclic alkyl radical having 1 to 12 carbon atoms;

such hydroxyl-containing polymers are described, for example, in DE-A 42 42 076;

Copolymers of 90 to 20% by weight of acrylic acid or methacrylic acid and 10 to 80% by weight of a compound of formula VII

wherein in the formula Rι _{7 is} hydrogen or the methyl radical, Riβ and R ₁₉ , which are the same or different, denote the methyl or ethyl radical, T for an optionally branched Alkylene radical having 1 to 5 carbon atoms and the amine nitrogen is optionally neutralized or quaternized, with a molecular weight of the copolymers, measured at a pH of 8.0, of less than 100,000;

such polymers are described for example in EP-B 278 267;

Polymers made by polymerizing

1 to 99% by weight, preferably 30 to 95% by weight, of water-soluble, ethylenically unsaturated monomers and / or unsaturated dicarboxylic acid anhydrides,

1 to 50% by weight, preferably 5 to 35% by weight, of an ethylenically unsaturated, mono- or polyalkoxylated monomer of the general formula VIII

H ^ ^ R20 _c = c VIII

_R 22 ^ ^ R ² ι

with R ²⁰ = H or methyl

R ²¹ = COOR ²³ , CH ₂ OR ²³ , CH ₂ N (R ²³ ) ₂

R ²² = H, COOH, CONHR ²⁴ and R ²³ = [-CHR ²⁵ -CHR ²⁶ -0-] _s -CHR ²⁵ -CHR ²⁶ -UR ²⁷

R ²⁴ = H or -CC -alkyl R25, R ² 6 = H or methyl s = 1 to 50

U = 0, NR ²⁸ , p

R ²⁷ = H, -CC ₂₄ alkyl, C ₆ -C ₂ aryl, C ₇ -C ₂₄ alkylaryl,

C ₂ -C ₂ saturated mono- or dicarboxylic acid residue R ²⁸ = -C-C alkyl, and

0 to 60% by weight, preferably 0 to 40% by weight, of further water-soluble monomers copolymerizable with the abovementioned monomers;

such polymers are described for example in DE-A 42 27 974; R) Water-dispersible and / or water-emulsifiable urethane oligomers with fat character (UR fat oligomers), containing at least predominantly non-crosslinked basic structure of the oligomer molecule, hydrocarbon fat residues together with 5 acid groups capable of salt formation, as described in DE-A 42 23 110 are.

As usual non-tanning fatliquors, especially those from the following groups of substances can be used: 10 natural fatliquors of animal origin, e.g. Fish oil, whale oil, cattle claw oil or tallow;

natural fatliquors of plant origin, e.g. 15 cottonseed oil, castor oil, sunflower oil, peanut oil or olive oil;

Hydrocarbons, e.g. Paraffin oil, low molecular weight mineral oil and low molecular weight polyethylene or polypropylene as aqueous dispersions;

functionalized paraffin derivatives such as chlorinated or sulfochlorinated paraffins;

25 - Polyalkylene oxides such as polyethylene oxide, polypropylene oxide or ethylene oxide-propylene oxide block copolymers as aqueous dispersions.

The above-mentioned non-tanning fatliquors are mostly pre-emulsified in 30 aqueous systems and usually contain emulsifiers. Such emulsions or dispersions can furthermore contain organic solvents in order to promote deeper penetration and uniform distribution over the entire leather surface. 35

The polymer tanning agents mentioned are usually in the form of aqueous solutions or aqueous dispersions in amounts of 3 to 100% by weight, preferably 10 to 50% by weight, of solid, based on the shaved weight, in the tanning step and in amounts of 0 to 40 50% by weight .-%, preferably 0 to 30 wt .-% solids, based on the pelt weight, used in the pretanning steps.

If non-tanning fatliquors are also used in the tanning step, they can be used in amounts of up to 80% by weight, preferably 45% up to 40% by weight, of solid, based on the fold weight. The weight ratio of polymer tanning agents to Non-tanning fatliquoring agents are in particular 99: 1 to 20:80, especially 95: 5 to 35:65.

The aldehydes or reactive carboxyl compounds mentioned in the pretanning step are normally used in amounts of 0.1 to 15% by weight, preferably 1 to 7% by weight, based on the weight of the raw material. If a mixture of polymer tanning agents and aldehydes or reactive carbonyl compounds is used here, the amount of aldehydes or reactive carbonyl compounds is usually reduced depending on the proportion of polymer tanning agents in the mixture. The weight ratio of polymer tanning agents to aldehydes or reactive carbonyl compounds is in particular 99: 1 to 1:99, especially 90:10 to 10:90.

In a particularly preferred embodiment of the process according to the invention, the following are used as polymer tanning agents or a mixture of polymer tanning agents and fatliquoring agents in the tanning step:

(i) • a copolymer of C ₆ - to C o -monoolefins with ethylenically unsaturated C - to Cβ-dicarboxylic acid anhydrides (according to group E);

(ii) a mixture of a copolymer of C ₆ - to C o -mono-olefins with ethylenically unsaturated C - to Cβ-dicarboxylic acid anhydrides (according to group E) and an acrylic or methacrylic acid homopolymer (according to group A) or one Graft polymer of a vegetable and / or animal oil onto a polymer based on monoethylenically unsaturated carboxylic, sulfonic or phosphonic acids, the

Anhydrides or their salts (according to group K) in a weight ratio of 99: 1 to 10:90, in particular 90:10 to 30:70;

(iii) a mixture of a copolymer of Cζ- to C o-mono-olefins with ethylenically unsaturated C - to Cβ-dicarboxylic acid anhydrides (according to group E) and a non-tanning lubricant based on hydrocarbon or polyalkylene oxide in the weight. Ratio of 99: 1 to 20:80, in particular 95: 5 to 35:65;

(iv) a mixture of a copolymer of acrylic or methacrylic acid with acrylic or methacrylic acid-Ci to C ₃ o-alkyl or -C ₂ - to C ₃ o-alkenyl esters (according to group B) and a Co- or terpolymer of C ₂ - to C -01efinen with acrylic or methacrylic acid and / or acrylic or methacrylic acid Ci to C ₃ o-alkyl or -C ₂ - to C ₃ o-alkenyl esters (according to group C) or one Terpolymer made of acrylic or meth acrylic acid, N- (3-di-Cι- to C -alkylaminopropyl) acrylamide or methacrylamide and acrylonitrile or acrylamide (according to group D) in a weight ratio of 99: 1 to 1:99, in particular 90:10 to 10:90.

In a further particularly preferred embodiment of the process according to the invention, the aldehydes or reactive carbonyl compounds used in the pretanning step are the abovementioned preferred aldehydes, alone or in a mixture with acrylic or methacrylic acid homopolymers (according to group A). Furthermore, in another particularly preferred embodiment, acrylic or methacrylic acid homopolymers (according to group A) are used alone in the pretanning step without aldehydes or reactive carbonyl compounds.

The leather and fur skins tanned by the process according to the invention can be aftertreated and finished, as usual, in a colored manner. The pretreatment of the bare skin before tanning, i.e. switch, liming, liming and pimples in particular are carried out as usual in the tannery.

The leather and fur skins produced by the process according to the invention have high qualities with regard to their physical fastness, in particular light fastness and heat yellowing stability. The leathers are usually very soft, and the degree of softness can be controlled by the amount and type of polymer tanning agents. The method according to the invention is universally applicable because it is suitable for the production of all types of leather of the most varied provenance.

The method according to the invention is extremely advantageous both economically and ecologically. It can be carried out easily and without problems and is inexpensive since the polymer tanning agents and aldehydes or reactive carbonyl compounds used are generally not expensive special chemicals. By avoiding the otherwise common environmentally harmful vegetable, synthetic and mineral tannins, the process according to the invention becomes extremely attractive. The wastewater pollution due to the better wasting of the tanning liquors is at significantly lower values. Examples

Unless otherwise stated, all the percentages in the pre-tanning relate to the weight of the pelvis and in the tanning to the fold weight.

Examples 1 to 3 (pre-tanning)

South German beef skin was soaked, cremated and descaled as usual and washed with 200% water at 25 ° C for 10 min. After the liquor had been drained, 40% of water at 25 ° C. and 6% of sodium chloride were added, after 10 minutes of 2% of 17% by weight aqueous formic acid and after a further 30 minutes of 8% of 10% by weight sulfuric acid ; the pH was then 3.0.

After exposure to the pimple for 90 minutes, the addition of 3% glutardialdehyde (example 1) or a mixture of 1.5% glutardialdehyde and 2% polyacrylic acid of molecular weight 2500 (example 2) or 15% polymethacrylic acid of molecular weight 10,000 (example 3) pre-tanning carried out. After 90 minutes, 20% 5% by weight aqueous sodium hydrogen carbonate solution was slowly added in 5 portions and the mixture was left to stand overnight. Thereafter, the pH was 4.0. It was then wilted and folded to the desired final thickness.

Examples 4 to 10 (tanning)

The pretanned cowhide from Examples 1 to 3, cut to the fold thickness of 0.8 mm, was washed with 200% water at 30 ° C .; after 10 minutes the liquor was drained. The tanning took place after addition of a further 100% of water at 30 ° C. by the action of 6% of a 33% by weight aqueous dispersion or solution of the agent I for 60 minutes and then three times in each case 30% of a 33% by weight .-% aqueous dispersion or solution of a mixture of equal parts by weight of agent I and agent II for 90 minutes each for the first and second addition and overnight for the third addition. The pH was then 4.9.

100% water at 45 ° C. and, after 20 minutes, 10% 8.5% by weight aqueous formic acid were added to the leather; the pH was then 4.0. The leather was then washed, dyed, fixed and finished as usual. The following table shows the type of agents I and II used, where I is either a polymeric tanning agent with optionally greasing properties or an emulsified non-tanning fatliquor:

Tanning Pre-tanning Medium I Medium II Example No. Example 1

4 polymethacrylic acid

1 C ₂ θ / C ₂ -O-olefin / MSA- (molecular weight 10,000) copolymer

Acrylic acid / ethylene /

5 2 2-ethylhexyl acrylate- ^C ₁ 6 C ₂ o -alkyl acrylate /

Copolymer acrylic acid copolymer

6 rape oil / MSA- C _2θ / C ₂₄ -θ-θlefin / MSA-

2 graft polymer (91: 9) copolymer

Acryls & ure / N- {3-

7 3 Dimethylamino-Ciβ / C ₂₀ -alkyl acrylate / propyl) acrylamide / acrylic acid copolymer acrylonitrile terpolymer

8 3 polyethylene, emulsified C ₂₀ / C ₂ -α-olefin / MSA- (molecular weight 4000) copolyπter

9 polyethylene oxide

3 C2θ / C ₂ -α-olefin / MSA- (molecular weight 2000) copolymer

10 2 C _2θ / C ₂ -α-01efin / MSA copolymer

The leathers obtained according to Examples 4 to 10 were all satisfactory to very good in their properties, in particular they performed extremely well in the assessment of the light fastness and the heat yellowing stability. Thus, the leather from Example 10 was given a rating of 4 in the Xeno-Test ^® exposure (according to IUF 402) and a rating of 4 in the heat yellowing test (4 hours at 110 ° C.), whereas corresponding synthetic or vegetable tanned leather in these two tests only received grade 2 in each case.

Claims

claims

1. A process for the production of leather and furskin, characterized in that tanning is carried out in the absence of vegetable, synthetic and mineral tanning agents and only tanning agents are used for tanning, and optionally aldehydes or reactive carbonyl compounds are used for pretanning.

2. A process for the production of leather and furskin according to claim 1, characterized in that pretanning using aldehydes or reactive carbonyl compounds, polymer tanning agents or a mixture thereof and tanning using one or more polymer tanning agents or a mixture of polymer tanning agents and fats.

3. A process for the production of leather and furskins according to claim 2, characterized in that the Polymer¬ tanning agents in the form of aqueous solutions or aqueous dispersions in amounts of 3 to 100 wt .-% solids, based on the shaved weight, in the tanning step and in amounts of 0 to 50% by weight of solids, based on the bare weight, used in the pretanning step.

4. A process for producing leather and fur skins according to claim 2 or 3, characterized in that the following are used as polymer tanning agents or mixtures of polymer tanning agents and fatliquoring agents in the tanning step:

(i) a copolymer of C _& - to C o-monoolefins with ethylenically unsaturated C to Cβ-dicarboxylic acid anhydrides (according to group E);

(ii) a mixture of a copolymer of C _ß - bis

C o-monoolefins with ethylenically unsaturated C - to Cβ-dicarboxylic acid anhydrides (according to group E) and an acrylic or methacrylic acid homopolymer (according to group A) or a graft polymer of a vegetable and / or animal oil onto a polymer based on monoethylenically unsaturated Carboxylic, sulfonic or phosphonic acids, their anhydrides or their salts (according to group K) in a weight ratio of 99: 1 to 10:90; (iii) a mixture of a copolymer of Ce to

C ₄ o-monoolefins with ethylenically unsaturated C - to Cβ-dicarboxylic acid anhydrides (according to group E) and a non-tanning lubricant based on hydrocarbons or polyalkylene oxide in a weight ratio of 99: 1 to 20:80;

(iv) a mixture of a copolymer of acrylic or methacrylic acid with acrylic or methacrylic acid Ci to C ₃₀ alkyl or -C ₂ to C o-alkenyl esters (according to

Group B) and a copolymer or terpolymer of C ₂ -C ₄ -01efins with acrylic or methacrylic acid and / or acrylic or methacrylic acid-Cχ- to C ₃ o-alkyl- or -C ₂ - to C ₃ o- alkenyl esters (according to group C) or a terpolymer made from acrylic or methacrylic acid, N- (3-di-Cι- to C ₄ -alkylaminopropyl) acrylamide or methacrylamide and acrylonitrile or acrylamide (according to group D) in a weight ratio from 99: 1 to 1:99.