EP0963445A1 - Biologically degradable leather - Google Patents

Abstract

The invention relates to a method for producing leather which is both completely biologically degradable and fully wear resistant by means of: I) (pre)tanning using tanning agents containing aldehydes or carbomoyle sulfanate groups, II) optionally (re)tanning with polyasparaginic acids and/or polyasparaginic acid amides, III) bottoming with polyurethane and natural auxiliary agents, finish consisting of polyurethane and/or polyester amide and IV) optionally, after-treatment with leather conservation products.

Description

Biodegradable leather

The invention relates to biodegradable leather and a process for its production

Tanning converts animal skin with the cross-linking of collagen in leather. One of the most important characteristics of leather is the increased shrinking temperature compared to untanned skin. the improved hot water resistance, and the white appearance (non-transparent) after drying

The type of tanning that is still dominant today is chrome tanning, in which covalent bonds with the carboxyl groups of collagen are formed using chromium (III) compounds under the influence of OH ions. The hydrogen bond bonds obtainable with polyfunctional vegetable tanning agents form part of the Amide groups of collagen, on the other hand, are much weaker, which also results in a moderately increased shrinking temperature. Also aliphatic aldehydes, such as Glutardialdehyde, which leads to crosslinking via the primary amino groups of collagen, has been recommended as tanning agents (US Pat. No. 2,941,859).

The use of aliphatic diisocyanates such as hexamethylene diisocyanate (DE-PS 72 981) has not been able to gain acceptance for toxicological reasons

The use of bisulfite-blocked aliphatic, cycloaliphatic or aromatic dusocyanates such as recommended in US Pat. Nos. 2,923,594 and 4,413,997

Hexamethylene diisocyanate, isophorone diisocyanate and tolylene diisocyanate as tanning agents result in light, in the case of aliphatic isocyanates, even lightfast leathers, but the tanning liquors are not pH-stable.

The automotive industry is increasingly requesting leather that is free of heavy metals on the one hand and that can be disposed of easily, for example, by composting. Since leather is "skin that no longer rot" according to a definition by Stather and Pauligk (Ges Abh of the German Leather Institute Freiburg Y∑ (1962), p 37), a conflict of objectives seems preprogrammed here. Compostable leather does not correspond to the definition in question, and one had to assume that such "leather" would also lack some of the properties that make it suitable for everyday use. This means that tanning, among other things is to be understood as a conservation method

According to the guidelines of the German Agricultural Working Group on Waste (LAGA 10), (conventionally manufactured) leather is one of the substances that must not be disposed of in composting plants because they are not biodegradable and because of their heavy metal content they pose a risk to humus and groundwater

The search for biodegradable tannins of natural origin is ongoing (see e.g. H Oertel, G Reich, L Meyer, E Lange "Custom made vegetable tannins - a contribution to securing the raw material base of the leather industry", Das

Leder 1994, pp 188 to 198) However, even tannins of natural origin are not eo ipso biodegradable, because they are produced by the plant for protection against attack by microbes and fungi and against being eaten, see JB Harborne, Ecological Biochemistry, Heidelberg 1995, p. 170

It hardly seemed possible to meet the requirements placed on biodegradable leather

On the one hand, the customer naturally expects biodegradable leather to be fully usable, on the other hand, the conservation of such leather raises problems. Leather is a hydrophilic material with a very large inner

Surface and therefore forms an ideal breeding ground for bacteria and fungi Microbes frequently release material-damaging enzymes during their growth. Microbes and fungi growing in leather are also undesirable for reasons of hygiene

Tanning has the consequence, among other things, that biodegradation of protein is prevented. Biological degradation of tanned goods thus far seemed to be a contradiction in terms From DE-OS 4 422 246 it is known that leather can be biodegraded with thermophilic microorganisms in the presence of oxygen. Inorganic ingredients accumulate as chromium-III-oxide or chromium-III-salt and can be recycled. This process provides a decisive step towards the biodegradability of leather However, it often places difficult requirements that can be met with regard to the usable microorganisms and the inorganic ingredients

Surprisingly, it has now been found that without chromium, titanium, iron, aluminum and zircon tanning materials, biodegradable but still usable leathers can be obtained if you pre-tanned or tanned with a reactive organic tanning agent and then used for the subsequent processes largely or completely biodegradable products used

The invention thus relates to a process for the production of leather, according to which

I merely tanned with a) aldehydes or b) bisulfite-blocked polyisocyanates,

II optionally tanning the product obtained with a) polyaspartic acid, its salts and / or its anhydrides and / or b) polyaspartic acid amides,

III a) the product obtained is primed with polyurethane and auxiliaries based on natural substances, b) a finish made of polyurethane and / or polyester amide is applied and

IV if necessary, the leather thus treated is subsequently treated with a leather preservative. Products which are biodegradable according to DIN 54 900, part 3 (draft) are preferably selected as tanning agents and auxiliaries within the scope of the invention. At least 60% by weight of the sum of all are preferred used tannins and auxiliaries biodegradable

Preferred aldehydes I a) include formaldehyde, acrolein, crotonaldehyde, glyoxal, glutardialdehyde and aldehydes obtainable by oxidation of fats - that is to say compounds and mixtures as described, for example, by F Stather, "Gergerochemistry and Gerger Technology", Akademie Verlag Berlin 1967, p

Preferred "bisulfite-blocked polyisocyanates" I b) are the reaction products

A organic polyisocyanate,

B based on the isocyanate equivalent of A, 0 to 0.4 equivalents of polyether alcohol with built-in polyalkylene oxide units (the equivalents relate to the hydroxyl groups of the polyether alcohol), the polyalkylene oxide units being 40 to 100, preferably 50 to 100 mol% consist of polyethylene oxide units with a sequence length of 5 to 70, preferably 6 to 60, in particular 7 to 40,

C optionally other NCO-reactive components, and

D ammonium or alka bisulfites or disulfites

The above reaction products I b) can be obtained from the intermediates obtainable from A, B and, if appropriate, C with NCO contents of 3 to 50, preferably 5 to 45, in particular 20 to 45% by weight (based on the intermediate) by subsequently blocking the free ones Obtaining isocyanate groups The products I b) then - calculated as sodium salt and based on solids - contain 9.7 to 78, preferably 14 to 74, in particular 46.5 to 74% by weight of carbamoyl sulfonate groups Suitable organic polyisocyanates A) are aliphatic, cycloaliphatic, araliphatic, aromatic or heterocyclic polyisocyanates as described, for example, by W. Siefken in Liebigs Annalen der Chemie 562, pages 75 to 136.

Preferred polyisocyanates A) are compounds of the formula Q (NCO) _n with an average molecular weight below 800, where n is a number of at least 2, preferably from 2 to 4, Q is an aliphatic C4-C _] 2-hydrocarbon radical, a cycloaliphatic Cg-C ^ Hydrocarbon residue, an araliphatic C7-C15

Hydrocarbon radical or a heterocyclic C2-C _] 2 radical having 1 to 3 hetero atoms from the series oxygen, sulfur, nitrogen, for example (i) diisocyanates such as ethylene diisocyanate, 1,4-tetramethylene diisocyanate, 1,6-hexamethylene diisocyanate, 1,12-dodecane diisocyanate, cyclobutane-l, 3-diisocyanate, cyclohexane-1,3- and -1,4-diisocyanate and any mixtures of these isomers, 1-isocyanato-2-isocyanatomethyl-cyclopentane, l-isocyanato -3,3,5-trimethyl-5-isocyanato-methyl-cyclohexane, 2,4- and 2,6-hexahydrotoluenediisocyanate and any mixtures of these isomers, hexahydro-1,3- and / or -1,4-phenylene diisocyanate, per - Hydro-2,4'- and / or -4,4-diphenylmethyl diisocyanate, 1,3- and 1,4-phenylene diisocyanate, 2,4- and 2,6-tolylene diisocyanate and any mixtures of these isomers ,

Diphenylmethane-2,4'- and / or -4,4'-diisocyanate, naphthalene-1,5-diisocyanate, polyisocyanates containing uretdione groups such as e.g. the bis (6-isocyanatohexyl) uretdione or the dimer of l-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane containing the uretdione structure and any mixtures of the aforementioned polyisocyanates; (ii) trifunctional and higher functional polyisocyanates such as the isomers of

Triisocyanatotriphenylmethane series (such as triphenylmethane-4,4 ', 4 "-triisocyanate) and their mixtures; (iii) compounds prepared by allophanatization, trimerization or biuretization from the polyisocyanates (i) and / or (ii) which have at least 3 isocyanate groups per molecule Examples of polyisocyanates produced by trimerization are the trimerizate of l-isocyanato-3,3,5-trimethyl-5-isocyanatomethylcyclohexane obtainable by isocyanate formation and the trimerization of hexamethylene diisocyanate, optionally in a mixture with 2,4'-diisocyanate toluene Polyisocyanates containing isocyanurate groups, examples for polyisocyanates produced by biuretization are Tπs- (ιsocyanatohexyl) -bιuret and its mixtures with its higher homologs, such as are accessible, for example, according to DE-OS 23 08 015

Particularly preferred polyisocyanates A are those with a molecular weight of 140 to 400 with NCO groups bonded to aliphatics or cycloahphates, such as, for example, 1,4-dnsocyanatobutane, 1,6-dnsocyanatohexane, 1,5-dusocyanato-2,2-dimethyl- pentane, 2,2,4- or 2,4,4-tπmethyl-l, 6-dnsocyanatohexane, 1,3- and 1,4-dusocyanatohexane, l-isocyanato-3,3,5-tπmethyl-5- Isocyanatomethyl-cyclohexane, 1-isocyanato-1-methyl-4-isocyanatomethyl-cyclohexane and 4,4'-dnsocyanatodιcyclohexyl-methane, and any mixtures of such diisocyanates. Also araliphatic polyisocyanates such as the xylylenedusocyanates of the formulas

can be used

The above dnsocyanates are preferably used. However, monofunctional a phatic isocyanates such as, for example, butyl isocyanate, hexy socyanate, cyclohexy socyanate, steary socyanate or dodecyl isocyanate and / or polyisocyanates with an average functionality of 2.2 to 4.2 can also be used

The highly functional polyisocyanates are preferably essentially composed of tπmerem 1,6-dnsocyanatohexane or l-isocyanato-3,3,5-tπmethyl-5-isocyanatomethyl-cyclohexane and optionally dimeric 1,6-dnsocyanatohexane or l-isocyanato-3 , 3,5-tπmethyl-5-ιsocyanatomethyl-cyclohexane and the correspondingly higher homologues existing isocyanurate groups and optionally polyisocyanate mixtures containing uretdione groups with an NCO content of 19 to 24% by weight, as obtained by known catalytic trimerization and with isocyanurate formation of 1,6-dnsocyanatohexane or l-isocyanato-3,3,5-tπ-methyl-5-ιsocyanatomethyl-cyclohexane, and the preferably have an (average) NCO functionality of 3.2 to 4.2

Further suitable polyisocyanates A are polyisocyanates prepared by modification of aliphatic or cyclophatic dusocyanates with uretdione and / or isocyanurate, urethane and / or allophanate, biuret or oxadiazine structure, as described, for example, in DE-OS 1 670 666, 3,700 209 and 3 900 053 and are described by way of example in EP 336 205 and 339 396. Suitable polyisocyanates are, for example, also the polyisocyanates containing ester groups, such as, for example, the tetrakis and / or tiisocyanates accessible by reacting pentaerythritol or tπmethylolpropane silyl ethers with isocyanatocapronic acid chloride -OS 3 743 782) It is also possible to use trans-isocyanates such as Tπs-isocyanatodicyclohexylmethane

In both cases, the use of monofunctional and preferably more than functional isocyanates is preferably limited to amounts of at most 10 mol%, based on all polyisocyanates A.

However, the abovementioned aliphatic, cycloaliphatic and araliphatic diisocyanates are very particularly preferred

The polyether alcohols B are accessible in a manner known per se by alkoxyation of suitable starter molecules. For the preparation of the polyether alcohols, any mono- or polyhydric alcohols with a molecular weight of 32 to 250 can be used as starter molecules. Preferred starter molecules are monofunctional a phatic Cj-Cis , preferably C1-C4 alcohols. The use of methanol, butanol, ethylene glycol monomethyl ether or ethylene glycol monobutyl ether as starter is particularly preferred

Alkylene oxides suitable for the alkoxylation reaction are, in particular, ethylene oxide and propylene oxide, which are in any order in the alkoxylation reaction Any other epoxides, such as butylene oxide, dodecene oxide or styrene oxide, can also be used. Pure polyethylene oxide alcohols are particularly preferred

Polyalkylene oxide alcohols containing ester groups can also be used. Suitable polyalkylene oxide alcohols containing ester groups are OH-terminated polyester ethers which are obtained by reacting aliphatic C2-Cg-dicarboxylic acids or their esters or acid chlorides with polyethers from the group of polyethylene oxides, polypropylene oxides, their mixtures or mixed polyethers Equivalents of the polyether 0.8 to 0.99 equivalents of carboxyl groups or their derivatives are used, are available and have an average molecular weight below 10,000, preferably below 3,000

The NCO-reactive components C which are optionally used also include mono- to tetra-functional building blocks such as those used in polyurethane chemistry

Alcohols, amines, amino alcohols and mercaptans with molecular weights below 6,000, preferably below 2,000, such as polyesters, polyether esters and polycarbonates, provided they do not fall under definition B.

Preferred components C are "fatty" or "post-fatty" long-chain, optionally branched so-called fatty alcohols or fatty amines with 12 to 30 carbon atoms and OH groups containing esters of natural fatty acids such as stearic acid, oleic acid, palmitic acid, linoleic acid, linolenic acid etc

Very particularly preferred components C are natural OH groups

Fats and oils such as castor oil

The reaction products I b) from components A to D can contain up to 20% by weight of residues of component C.

Preferred blocking agents D are preferably the sodium salts of the sulphurous or disulphurous acid, ie sodium bisulfite (NaHS03) or sodium disulphide (Na ₂ S ₂ O ₅ ) The other alkali and ammonium salts of these acids, namely potassium bisulfite, potassium disulfite, lithium bisulfite, lithium disulfite, ammonium bisulfite, ammonium disulfite and simple tetraalkylammonium salts of these acids such as, for example, tetramethylammonium bisulfite, tetraethylammonium bisulfite, etc., are preferably used as blocking agents aqueous solutions with solids contents of 5 to 40% by weight are used

The reaction products I b) can be prepared, for example, as follows

In a first step, the polyisocyanate A is reacted with the polyether alcohol B until all OH groups have been urethanized. The NCO-terminated prepolymer thus obtained is then blocked in a second step with alkali metal or ammonium bisulfite or disulfite until all of the NCO- Groups are implemented

The entire process is particularly preferably carried out as a one-pot process without solvents. The 1 step of the reaction is carried out in the temperature range up to 130 ° C., preferably in the range between 50 ° C. and 120 ° C., particularly preferably between 80 ° C. and 110 ° C. The reaction can be followed by titration of the NCO content or by measurement of the IR spectra and evaluation of the carbonyl band at approx. 2 100 cm "! And is complete when the isocyanate content is not more than 0.1% by weight above the value which should be achieved with complete sales. As a rule, reaction times of less than 4 hours are sufficient.

By using catalysts such as dibutyltin dilaurate, tin (II) octoate or 1,4-diazabicyclo [2,2,2] octane in amounts of 10 to 1,000 ppm, based on the reaction components, the reaction can be accelerated NCO prepolymers thus obtained with NCO contents of 5 to 45% by weight are then reacted in a 2 step at 0 to 60 ° C., preferably at 10 to 40 ° C., with aqueous solutions of alkali metal or ammonium sulfites and water, until all NCO groups have reacted This generally requires reaction times of 1 to 12, preferably 3 to 8, hours. The end products are optically clear aqueous solutions, in In a few individual cases, stable, finely divided emulsions with average particle diameters below 8000 nanometers. It may be advantageous to first react the NCO prepolymers with 20 to 50% by weight aqueous solutions of the alkali metal or ammonium bisulfites or disulfites and after 5 to 45 Minutes to add the remaining water, so that then a solids content of the aqueous preparations of 10 to

50% by weight, preferably 25 to 40% by weight, results

To achieve the tanning effect, it must be stated that the pH should be at least 7.5 to preferably a maximum of 9.5. Under these conditions, the blocked isocyanate groups react with crosslinking of the collagen (with simultaneous elimination of the bisulfite group)

To base the reaction products I b), all known tamping agents customary in tannery are suitable. Sodium carbonate and hydrogen carbonate, magnesium oxide, dolomite, tertiary amines, etc. The controlled addition of sodium or potassium hydroxide is generally possible (but not usual). Magnesium oxide is particularly preferred

Tanning with the reaction products I b) does not require a low pH, as is customary, for example, in mineral tanning. This saves the addition of salt (pimples). For example, a mere pH value of 5 to 8 ( preferably descaled by 7), the reaction product I b) added and the basification started after an hour's running time (in the case of annealed magnesium oxide, the addition can be started immediately), depending on the mechanical flexing action and thickness, as well as digestion (eg enzymatic) of the bare can the

Tanning, and preferably the simultaneous basification, should be completed in 4 to 6 hours. In general, however - as is usual with chrome tanning - after the lead time of 1 hour and after addition of the basifying agent in two further steps (each after 1 hour running time) Run overnight, rewind the next morning and continue working as usual

Amounts of 1 to 20, preferably 3 to 15,% by weight of reaction product Ib), based on the bare weight, are generally used Implementation product of tanned leather with shrinkage temperatures of over 70 ° C, preferably over 75 ° C, as a preliminary stage (analogue wet blue) for retanning

Bisulfite-blocked polyisocyanates I b) of the type described are known from DE-OS 4 422 569

The use of the bisulfite-blocked polyisocyanates described, which contain polyethylene oxide groups, has application-related advantages which consist in the fact that residual liquors of the tanning are obtained which are free from heavy metal ions. The shrinkage temperatures of the leather which can be achieved with these products are higher

70 ° C, mostly over 80 ° C, and thus within the shrinkage temperature range required for most types of leather

The term "polyaspartic acid" II a) hereinafter includes its salts, preferably its ammonium, potassium and sodium salts, and their anhydrides, such as polysuccinimide, and copolymers obtained by partial dehydration, which also contain aspartic acid units in addition to the succinimide units Polysuccinimide can form polyaspartic acid by hydrolysis during use

The production of polyaspartic acid and its derivatives has long been the subject of numerous publications. The preparation can be carried out by thermal polycondensation of aspartic acid (J Org. Chem. 26, 1084 (1961)), see also DE-OS 2 253 190, US Pat. Nos. 4,696,981, 5,296,578 and 5,288,783

The US Pat. No. 4,839,461 (= EP-A 256 366) describes the preparation of polyaspartic acid from maleic anhydride, water and ammonia. Maleic anhydride is then converted into the monoammonium salt in aqueous medium with the addition of concentrated ammonia solution. This maleic monoammonium salt can preferably be used in 150 to 180 ° C in a reactor with a residence time of 5 to 300 minutes subjected to a thermal, optionally a continuous polymerization and the polysuccinimide obtained is reacted by hydrolysis to polyaspartic acid or a salt thereof. In a preferred embodiment, polyaspartic acid II a) contains essentially recurring units of the following structure;

H

- IM - ^■ C - CO - H a) _CH (α-form)

I ²

COOH

and

b) - N - C - C - CO - (ß-form)

I 2

COOH

In general, the proportion of the β-form is more than 50%, in particular more than

70%, based on the sum of a + b.

In addition to the repeating aspartic acid units a) and b), further repeating units can be included, e.g.

c) Malic acid units of the formula

H H O - C - CO - O - C - C CO - I H "

CH, COOH

I.

COOH

d) Maleic acid units of the formula

H H

C C

/ \

^• CO CO e) Fumaric acid units of the formula

CO -

H c:: HC

/

CO

The "further" recurring units can be present in the polyaspartic acid in amounts of up to 100% by weight, based on the sum a + b

Preferred polyaspartic acids II a) have, as the weight average, molecular weights determined by gel permeation chromatography (calibrated with polystyrene) from 500 to 10,000, preferably 1,000 to 5,000, in particular 2,000 to 4,000

The polyaspartic acid II a) can be used in amounts of 0.1 to 20, preferably 0.5 to 12, in particular 1 to 8% by weight (based on bare weight in the case of tanning, on fold weight in the case of retanning)

In tanning and retanning, the polyaspartic acid can be used in combination with other tanning agents, preferably in a weight ratio of from 19 to 91. Examples of other tanning agents are vegetable tanning agents and synthetic organic tanning agents (so-called “syntans”), including the resin tanning agents. Examples of such other tanning agents are those in the The following literature describes F Schade and H Träbel, "Recent developments in the field of synthetic organic tanning agents", Das Leder 33 (1982), 142-154, H Träbel and K -H Rogge, "Retannage and Retanning Materials", JALCA 83 ( 1988), 193-205, K Faber, "Tanning agents, tanning and retanning", Vol 3 in H Herfeld, Library of Leather, Frankfurt 1984, EP-A 118 023, 372 746, DE-OS 3 931 039

The polyaspartic acid is usually used immediately before coloring

The use of polyaspartic acid will be explained below Folded, pre-tanned leather ("wet blue") is neutralized in a barrel after a brief wash, a pH range of 4.5 to 5 being reached. Then this neutralization liquor is drained off, 100% by weight (based on the shaved weight of the leather) water of 30 to 50 ° C. and 2 to 5% by weight of polyaspartic acid or its derivative are added, the mixture is left to run and dye for 2 hours.

Polyaspartic acid and its use as a tanning agent are known from DE-OS 4,439,990.

Preferred polyaspartic acid amides II b) are products with a number average molecular weight of 700 to 30,000, preferably 1,300 to 16,000, obtainable by reacting

A. polysuccinimide with a number average molecular weight of 500 to 10,000, preferably 500 to 6,000, in particular 1,000 to 4,000, with

B. 5 to 90, preferably 20 to 80 mol%, based on succinimide units of polysuccinimide A, primary and / or secondary amine whose nitrogen substituents contain 1 to 60, preferably 1 to 36 carbon atoms, by fluorine atoms, hydroxyl, amino groups and / or silicon-organic

Residues may be substituted and / or interrupted by oxygen atoms, ester, amide, urea or urethane groups, at least 2.5, preferably at least 15, in particular at least 30, in particular at least 30 mol% of the nitrogen substituents of the amine containing at least 12 carbon atoms - if not

C. (i) derivatives of C \ -C \ g monocarboxylic acids and / or C2-C 1 Q-dicarboxylic acids and / or (ii) monoisocyanates, dusocyanates or epichlorohydrin (for reacting amino and / or hydroxyl groups on the Nitrogen substituents of the reaction product from A and B), and (mandatory)

D. 95 to 10, preferably 80 to 20 mol% ring-opening base in the presence of water. The polysuccinimide A serving as the starting product for the polyaspartic acid amides II b) to be used according to the invention is known. The preparation from aspartic acid can thus take place with elimination of water; see. z BJ Org Chem 26 (1961) 1084, FR 70 24 831, P Neri in J Med Chem 16 _. (1973), 893, U.S. Patent 4,363,797

Other processes are based on maleic acid or its anhydride and ammonia (DE-OS 4 305 368, US Pat. No. 4,839,461). For example, polysuccinimide can be reacted with 80 to 100 mol% maleic acid and 20 to 0 mol% succinic anhydride (as a chain terminator) with ammonia with removal of the water of reaction at elevated temperature, generally at 85 to 240, preferably 120 to 180 ° C.

US Pat. No. 4,839,461 (= EP-A 256 366) describes the preparation from maleic anhydride, water and ammonia. Then maleic anhydride is converted into the mono-ammonium salt in an aqueous medium with the addition of concentrated ammonia solution. This maleic acid monoammonium salt can preferably be subjected to thermal, optionally continuous polycondensation to polysuccinimide in a reactor at 150 to 180 ° C. with a residence time of 5 to 300 minutes

The polysuccinimide A serving as the starting compound can also be prepared by dehydrating polyaspartic acid or by thermal polycondensation of aspartic acid.

The dehydration of aspartic acid or polyaspartic acid to polysuccinimide can be carried out at elevated temperature, preferably at 100 to 240 ° C., optionally in the presence of a catalyst, for example in the presence of 0.01 to 1% by weight, based on polyaspartic acid, of an acidic catalyst such as sulfuric acid. Phosphoric acid, methanesulfonic acid.

Preferred amines B include secondary and - preferably - primary amines, such as, for example, monofunctional polyetheramines with a primary or secondary amino group such as α-methyl-ω-amino-polyoxyethylene, α-methyl-ω-aminopropyl-triethoxy-silane, aminopropyl-trimethoxy-silane, aminopropyl-heptamethyl-trisiloxane, N-2-aminoethyl-aminopropyl-dimethyl-ethoxy-silane, N-2-aminoethyl-aminopropyl-methyl-dimethoxysilane, perfluorohexyl-ethylamine, N-aminoethyl-N-methyl-perfluoro-octylsulfonamide, N, N-dimethylethylene diamine, methylamine, diethylamine, butylamine,

Stearylamine, tallow fatty amine, oleylamine, undecylamine, dodecylamine, octylamine, hexylamine, eicosanylamine, hexadecylamine, 2-ethylhexylamine, morpholine, ethanolamine, diethanolamine, bis-2-hydroxy-propylamine, bis-3-hydroxy-propylamine, 2- or 3-hydroxypropylamine, ethoxy-ethylamine, ethoxy-ethoxy-ethylamine, butoxy-ethoxy-ethoxy-ethylamine, 2-methoxy-ethyl-amine, tetrahydrofurylamine, 5-aminopentanol,

Benzylamine, 4-aminocyclohexylamine, taurine Na salt, glycine methyl ester, N-methylaminoethyl sulfonic acid Na salt, dehydroabietylamine, stearyloxypropylamine,

(C, HAN - (CH, ₂ ) /, ₂ - NH CH,

(CH ₃ ) ₂ NC - C - NH,

H, H,

CH,

CH ₃ ^ ^~ \

| ON - (CH ₂ ) ₃ - NH ₂

(C ₂ H ₅ ) ₂ N - (CH ₂ ) ₃ - C - NH ₂ ■ \ f π

CH ₃ CH ₃ CH ₃

ON - C - C NH,, (C ₂ H ₅ ) ₂ N - C - C - NH ₂ . ( ^CH 3) ₂ ^{N "} g - C - NH ₂

\ / H, H ² H ₂ H ²

CH, CH ₃ N - (CH ₂ ) ₃ - NH ₂ ^" N _ _ _ _{(CH3) 2N} 'NH 2' \ / H ₂ H ^{2 H} 2 I

CH ₃ NH,

/ \ / \

CH ₃ - NN - C - C - CNN - CH,

H ₂ HH ₂

or their mixtures

The reaction of polysuccinimide with amines is known in principle, see, for example, DE-OS 2 253 190, EP-A 274 127, 406 623 and 519 1 19, US Pat. Nos. 3,846,380, 3,927,204 and 4,363,797, P. Neπ et al, Macromol Syntheses 8, 25 The reaction can be carried out in excess amine B, but is preferably carried out in organic solvents which are inert under the reaction conditions. Lactams such as caprolactam, pyrrolidone, N-methylpyrrolidone, N- Methyl caprolactam, polyalkylene diols and their mono- and diethers, such as ethylene glycol, diethylene glycol, triethylene glycol, ethylene glycol dimethyl and diethyl ether and diethylene glycol monoethyl ether, as well as dimethylformamide and dimethyl sulfoxide. The solvent content will generally not exceed 30% by weight, based on the total reaction mixture

The reaction mixture can, although not preferred, contain water or paraffins. The reaction is carried out in a temperature range from 20 to 160 ° C., the reaction times being between 2 to 72 hours. The product can be removed by distillation of the solvent or by precipitation of the product in isolated from a non-solvent such as acetone, methanol, ethanol, water, isopropanol and then, if desired, dried. It is also possible to disperse the reaction mixture in the water phase without further purification steps

The polyaspartic acid amides II b) can be prepared from the reaction product from A and B by opening the remaining built-in succinimide rings. The ring-opening bases C include alkali metal hydroxides, carbonates and hydrogen carbonates, in particular sodium and potassium hydroxide and sodium carbonate, and ammonia and amines - including amines B - in question According to a particular embodiment, maleic acid or maleic anhydride and aqueous ammonia in a molar ratio of 0.75 to 1.5 can be mixed and water can be distilled off. If appropriate, one of the above-mentioned organic solvents can be added during the reaction. When the polysuccinimide has reached the desired molecular weight, amine becomes B metered in and reacted at 130 to 160 ° C. A reaction time of 3 to 18, preferably 4 to 8 hours is generally sufficient for the reaction of the amine B. An organic solvent can optionally be added. The polyaspartic acid amide II b) is formed directly, which can be easily dispersed in water by simultaneously opening the remaining built-in succinimide rings with ring-opening base D

The polyaspartic acid amides to be used according to the invention contain recurring structural units of the formulas in an idealized form

(A)

, 1 "N.

R ^

(B) (C)

(D)

wherein

R ¹ , R ^{2 are} hydrogen or one of the radicals referred to above as nitrogen substituents, with the proviso that at least one of the two radicals is not equal to hydrogen, and

M ⁺ for H ⁺ or an alkali ion, an NH4-io or a primary, secondary or tertiary aliphatic ammonium residue, which is preferably at least one

Cι-C22 alkyl or hydroxyalkyl group, stands

Suitable M ⁺ radicals are, for example, hydroxyethylammonium, dihydroxyethylammonium, trishydroxyethylammonium, triethylammonium, ammonium, butylammonium, benzyltrimethylammonium, morpholinium, stearylammonium, oleylammonium

The structural units I are preferably present in the polymer in an amount of 5 to 90, in particular 20 to 80 mol%, based on all the recurring units. Preferred polyaspartic acid amides contain an average of at least one C 1 -C 22 -alkyl and / or alkylene radical per structural unit I.

The structural units II are preferably contained in the polymer in an amount of 95 to 10, in particular 80 to 20 mol%, based on all the recurring units. Polyaspartic acid amides whose carboxyl groups are present in partially neutralized form are particularly preferred. The preferred degree of neutralization is 10 to 70, preferably 20 to 50%. Structure IIC accounts for 0 to 20 mol%, based on structure II. The structural units III are present in the polymer in an amount of 0 to 5 mol%, based on all repeating units. Preferred polyaspartic amides contain less than 1 mol% of the structural units III

In the event that polysuccinimide A has been prepared from polyaspartic acid which contains the above-mentioned repeating units C), the carboxyl groups of these repeating units can also be amidated

Suitable nitrogen substituents Rl, R ^ independently of one another include, for example, optionally hydroxyl-substituted C i -C22 alkyl or C2-C22 alkenyl groups of hydroxyethyl, hydroxypropyl, methyl, ethyl, butyl, hexyl, octyl, octenyl, decyl, undecyl, undecenyl, Dodecyl, tetradecyl, hexadecyl, oleyl, octadecyl, 12-hydroxy-octadecenyl, C5-Cιo-cycloalkyl radicals such as cyclohexyl, Ci2-C3o ests such as stearoyloxyethyl, stearyloxyethoxyamethyl and stearyloxyethoxyamoyl and stearyloxyethoxyethyl and stearyloxyethoxyethyl and formloxy interrupted by oxygen atoms, ester, amide and urethane groups

wherein

R ^5, R ⁶ Cι-C ₃₀ alkyl, C ₂ -C 3 _{0 alkenyl;} C ₅ -Cι ₀ cycloalkenyl,

R ⁷ to R ^{9 are} C -C4 alkyl or alkoxy and

M ^{+ has} the meaning given above

Nitrogen substituents which are interrupted by oxygen atoms, ester, amide or urethane groups can in principle be formed either by using amines B already containing these groups or subsequently by reacting initially introduced reactive nitrogen substituents with suitable reaction partners

Amide and ester groups can, for example, by subsequent reaction of already introduced aminoalkyl or hydroxyalkyl radicals with reactive carboxylic acid derivatives, preferably derivatives of Ci-C g-monocarboxylic acids or C2-C10-dicarboxylic acids, such as anhydrides or chlorides, for example acetic anhydride, acetylchloride, acrylic - and methacrylic acid chloride, methacrylic anhydride, succinic anhydride,

Maleic anhydride, stearic acid chloride, phthalic anhydride, are introduced

Urethane groups and urea groups can be introduced, for example, by subsequent reaction of amino or hydroxyalkyl radicals already introduced with mono- or di-isocyanates such as butyl isocyanate, steary socyanate, hexamethylene diisocyanate, toluylene densocyanate, isophorone nasocyanate, 1-isocyanatomethyl-4-methyl-4-cyclohexyl Monoisocyanates are particularly preferred. Crosslinked products are not preferred

Nitrogen substituents interrupted by oxygen atoms are best introduced using appropriate amino ethers B. Epoxy groups can be introduced, for example, by subsequent epoxidation of alkenyl groups that have already been introduced, for example with peracids. Another possibility is alkylation with epichlorohydrin

The polyaspartic acid amides II b) are very often self-dispersing, especially if the proportion of the structural units I is less than 50 mol%. However, external dispersants can also be used, as such cationic, anionic and nonionic dispersants are suitable in principle, as described, for example, in "Methods of organic chemistry" (Houben-Weyl), 4 edition, volume XIV / 1, Georg Thieme Verlag, Stuttgart 1961, p 190 f

Preferred dispersants include, for example, Cg-Cig-n-alkyl sulfates, Cg-Cjg-n-alkyl-benzenesulfonates, Cg-C \ gn-alkyl-trimethyl-ammonium salts, n-di-Cg-C \ g-alkyl-dimethyl-ammonium salts, Cg-C gn-alkyl carboxylates, Cg-C i gn-alkyl-dimethylamine oxides, Cg-Ci-n-alkyl-dimethylphosphine oxides and - preferably - oligoethylene glycol mono-Cö-Cj alkyl ether with an average of 2 to 30 Ethoxy groups per molecule. The n-alkyl radicals can also be replaced by partially unsaturated linear aliphatic radicals. Particularly preferred dispersants are oligo- ethylene glycol _mono-Cιo-C] 4-alkyl ether with an average of 4 to 12 ethoxy groups per molecule, in particular oligoethylene glycol mono-C 2-alkyl ethers having an average of 8 ethoxy groups per molecule

Preferred dispersants further include oleic acid, oleic acid sarcosides, ricinoleic acid, stearic acid, fatty acid partial esters of polyols such as glycerol, trimethylolpropane or pentaerythritol and their acylation, ethoxylation and propoxylation products, for example glycerol monostearate and monooleate, sorbitan mono stearate and sorbitan mono stearate and sorbitan mono stearate and sorbitan mono stearate and sorbitan mono stearate and -trioleate and their reaction products with dicarboxylic acid anhydrides such as succinic anhydride, maleic anhydride, phthalic anhydride or tetrahydrophthalic anhydride, reaction products from bis- (hydroxymethyl) tricyclodecane and maleic anhydride or amine and their amine derivate anhydride, preferably in their amine formate, or amine and their derivative Particularly preferred dispersants are salts of long-chain fatty acids, preferably oleic acid and an amino alcohol, preferably hydroxyethylamine, bis-hydroxyethylamine or trishydroxyethylamine

The dispersion of the polyaspartic acid amides II b) can be prepared by dispersing the polyaspartic acid amides in an aqueous dispersant solution, preferably with heating to temperatures of 40 to 95 ° C., with stirring

In general, it is recommended to disperse the polyaspartic acid amides II b) directly from the reaction mixture, which may contain organic solvents, without intermediate isolation. For example, an aqueous dispersant solution can be metered into the reaction mixture with stirring at temperatures of 70 to 130 ° C. , so that a mixing temperature of 70 to 95 ° C. is obtained and the organic solvent is distilled off. Conversely, the reaction mixture can of course also be dispersed in aqueous dispersant solution or a mixture of reaction mixture and dispersant in water. Removal of the solvent can also be dispensed with In this case, however, the solvent content of the dispersion should not exceed 10% by weight

The dispersant content is generally not more than 30, preferably 3 to

15% by weight, based on the finished dispersion

The solids content of the dispersions can be 5 to 70% by weight. The average particle size of the dispersed polyaspartic acid amides is generally 100 to 1000, preferably 100 to 700 and in particular 100 to 400 nm

In order to facilitate the penetration of the auxiliaries into the leather, it may be desirable to reduce the particle size of the disperse phase. For this purpose, the pre-emulsion already obtained can be subjected to high shear conditions in known dissolvers, dispersing machines, such as in a jet disperser, or mixers with rotor The stator principle or high-pressure homogenizers are post-treated. The dispersion time can range from a few minutes to 4 hours. preferably carried out in a temperature range between 20 and 75 ° C. The pressure in dispersing machines can be 2 to 2 500 bar

The dispersions can be present in the form of pastes, in particular at solids contents above 40% by weight, but can be diluted well with water

Dispersions with a solids content below 40% by weight are in the form of pourable emulsions or microemulsions. The pH of the emulsions or pastes is between 4.5 and 12, preferably in the pH range between 4.5 and 10

The leather treatment can be carried out with an aqueous liquor which contains the polyaspartic acid amides II b)

For this purpose, the leather is brought into contact with the liquor by application by means of rollers or in a container, preferably in a tanning drum. After the treatment, the leather is dried

The individual process steps are to be illustrated using the following example

1 Neutralize the tanned leather

2 wash

3 addition of the liquor containing polyaspartic acid amides III

4 Reduction of the pH value by adding a carboxylic acid to pH values

<4.5, preferably 3.0 to 4.5

5 wash

6 drying

The above polyaspartic acid amides II b) and their use as leather auxiliaries are described in DE-OS 195 28 782 Preferred polyurethanes III a) and III b) (hereinafter simplified: “III”) are described, for example, in EP-A 572 256 and 593 975, in DE-OS 20 35 732 and 26 51 506 and in DE-PS 4 319 439. Particularly preferred polyurethanes III are polyurethanes having urea groups, which, according to known processes, maintain an equivalent ratio of isocyanate groups to isocyanate-reactive groups of 1: 1 to 2: 1

a) a diisocyanate component consisting of

al) hexamethylene diisocyanate or

a2) Mixtures of hexamethylene diisocyanate with a total of up to

60% by weight, based on the mixture, of l-isocyanato-3,3,5-trimethyl-5-isocyanatomethyl-cyclohexane and / or 4,4'-diisocyanatodicyclohexylmethane and / or l-methyl-2,4 (6 ) -diisocyanatocyclohexane with

b) a diol component consisting of

bl) at least one polyester diol of a molecular weight of 500 to 10,000 which can be calculated from the hydroxyl group content from (i) adipic acid and / or succinic acid and (ii) at least one alkane diol with 2 to 6 carbon atoms or

b2) a mixture of such polyester diols with up to 32% by weight, based on the total weight of component b), of alkane diols with 2 to 6 carbon atoms which may have ether groups,

c) a diamine component in an amount of 2 to 50 equivalent%, based on the total amount of the groups present in components b) and c) which are reactive towards isocyanate groups, consisting of cl) diamino sulfonates of the general formula

H2N - (- CH2-) _n -NH - (- CH2-) _m -SO ₃ Me

or

c2) Mixtures of diaminosulfonates cl) with up to 70% by weight, based on the total weight of component c), of ethylenediamine, if appropriate

d) hydrophilic polyether alcohols of the general formula

H-X-O-R

in an amount of up to 10 wt .-%, based on the total weight of the

Components b), c) and d), and optionally

e) water which is not included in the calculation of the equivalent ratio of isocyanate groups to groups which are reactive toward isocyanate groups,

are available, wherein in the general formulas mentioned

m and n independently of one another represent numbers from 2 to 6,

Me stands for potassium or sodium,

R represents a monovalent hydrocarbon radical having 1 to 12 carbon atoms, and

X denotes a polyalkylene oxide chain in the molecular weight range 88 to 4000, the alkylene oxide units of which at least 40% consist of ethylene oxide units and the rest of propylene oxide units. The diisocyanate component a) preferably consists exclusively of hexamethylene diisocyanate

The diol component b) consists either of bl) at least one polyester diol or b2) of a mixture of at least one polyester diol bl) with up to 32, preferably up to 10% by weight of at least one alkane diol with 2 to 6 carbon atoms, optionally containing ether groups

Suitable polyester diols b1) are those having a molecular weight which can be calculated from the hydroxyl group content 500 to 10,000, preferably 1,000 to 2,500, based on (i) adipic acid and / or succinic acid and (ii) alkane diols with 2 to 6 carbon atoms, optionally containing ether groups, such as, for example, Ethylene glycol, diethylene glycol, 1,4-butanediol, neopentyl glycol and / or 1,6-hexanediol polyester diols, only ethylene glycol and / or 1,4-

Butanediol have been used as the diol are particularly preferred.

The chain extenders which may optionally be used as hydroxyl groups and which may have ether groups and contain alkane diols with 2 to 6 carbon atoms are those of the type just mentioned by way of example.

The diamine component c) consists either of cl) diamino sulfonates of the general formula already mentioned above or of c2) mixtures of such diamino sulfonates with ethylenediamine, which, if at all, in amounts of up to 90, preferably up to 70 equivalent%, based on the Component c) amino groups reactive with isocyanate groups are used. Particularly preferred diaminosulfonates are the potassium or sodium salts of N- (2-aminoethyl) -2-aminoethanesulfonic acid

The diamine component c) is generally used in an amount of 1 to 10, preferably 2 to 5% by weight, based on the weight of component b). The optional structural component d) is a hydrophilic monohydric polyether alcohol of the general formula

H-X-O-R,

in which

R and X have the meaning already mentioned.

Such polyether alcohols are preferred for which

R represents an aliphatic hydrocarbon radical having 1 to 4 carbon atoms and

X represents a polyalkylene oxide chain in the molecular weight range 500 to 4,000, in which at least 40, in particular at least 70 and particularly preferably 100% of the alkylene oxide units, ethylene oxide units and the remaining alkylene oxide units are propylene oxide units.

Such monohydric polyether alcohols are prepared by alkoxylation of suitable starter molecules R-OH known per se, such as, for example, methanol, n-butanol, n-hexanol or n-dodecanol, with the preferred use of ethylene oxide and optionally propylene oxide, in the proportions corresponding to the above Alkylene oxides. Here, the above

Alkylene oxides are used as a mixture and / or in succession.

The monohydric polyether alcohols d) are used, if at all, in amounts of up to 10, preferably up to 3% by weight, based on the total weight of components b), c) and d).

Water is to be mentioned as a further structural component that may be considered in the production of the urea groups containing polyurethanes III, which is particularly to be considered as a reactant if, in the preparation of the polyurethanes, the chain extension reaction to be carried out in the last stage of previously prepared NCO prepolymers takes place in an aqueous medium, in particular when the diamines c) in dissolved in, based on the NCO groups of the NCO prepolymers, sub-equivalent amounts are used.

In addition to these structural components, trifunctional compounds in minor amounts are also possible in principle, such as, for example, glycerol or trimethylolpropane, which can either be incorporated in small amounts in the polyester b1) or can be used in free form as part of component b2). The concomitant use of such branching molecules must generally be compensated for by monofunctional compounds, so that, purely mathematically, linear polymers result again.

The polyurethanes III containing urea groups can be prepared from the structural components mentioned by way of example by any process of the prior art. However, the known prepolymer process is preferably used, in such a way that components b) and, if appropriate, d) and diisocyanate component a) are adhered to

NCO / OH equivalent ratio of 1.5: 1 to 4: 1, preferably 1.8: 1 to 2.5: 1 produces an NCO prepolymer or semiprepolymer and then reacted with component c) with chain extension .

The prepolymer or semi-prepolymer is generally solvent-free

Temperatures of 20 to 150 ° C and then dissolved in a suitable solvent. Of course, the prepolymers or semi-prepolymers can also be formed directly in a solvent. Particularly suitable solvents are solvents which are inert to isocyanate groups and are immiscible with water. Acetone is preferably used as the solvent. The prepolymers or semiprapolymers prepared in this way are reacted in the second reaction stage with component c) with chain extension. Here, the equivalent ratio of isocyanate groups of the prepolymers or semiprapolymers on the one hand to amino groups of component c) which are reactive toward isocyanate groups, on the other hand, preferably at 1 1 to 20 1 1.2 1 to 4 1 The chain extension reaction can be carried out in solution, preferably in an acetonic solution or in an aqueous medium, in such a way that the solution of the prepolymers or semiprapolymers in organic solvent with a solution of component c) in water with thorough mixing combined As already indicated, a chain extension reaction may also take place here by reaction of the NCO groups of the prepolymers or semiprapolymers with the water. In the above-mentioned, preferred 2-stage preparation of the polyurethanes III we containing urea groups rden the equivalent ratios between isocyanate groups and groups reactive to isocyanate groups of the two reaction stages within the scope of the disclosure made so selected that the total ratio of isocyanate groups to groups of components b) to d) which are reactive towards isocyanate groups corresponds to the ratio of 1 1 to 2 1 given above Water is never included in the calculation of the equivalent ratios mentioned

The chain extension reaction generally takes place within the temperature range of 20 to 50 ° C

In principle possible, but by no means preferred, the chain extension reaction can also take place in the melt, ie in the absence of solvents and of

Water take place (melt dispersion process).

The polyurethanes III are preferably applied in the form of aqueous dispersions

The term "aqueous dispersion" is also intended to encompass aqueous solutions which can be present when the concentration of hydrophilic centers in the urea group-containing polyurethanes is sufficiently high to make them water-insoluble To be guaranteed The dispersions to be used according to the invention are often aqueous systems which contain both dispersed and dissolved urea groups containing polyurethanes.

To prepare the aqueous dispersions, the above-mentioned starting materials a), b), c) and optionally d) and / or optionally e) are used in the proportions mentioned

Such particularly preferred polyurethanes III are known from DE-OS 195 17 185.

To prepare the dispersions, the chain-extended polyurethanes III or their solutions in organic solvents, if the chain extension reaction had been carried out in the absence of water, are mixed with the dispersing water, which is followed, if appropriate, by the distillative removal of at least some of the auxiliary solvent which may be used Chain extension reaction was carried out in an aqueous medium, further water can optionally be added to prepare the aqueous dispersions. In this case too, the auxiliary solvent used can of course be removed by distillation if desired.

In general, the total amount of water used is such that 25 to 50% by weight dispersions, based on the dispersed solids on the one hand and the continuous phase on the other hand, are present

Preferred polyurethanes III are also known, for example, from DE-OS 4,421,292. These are reaction products

a) at least one glycerol monoester of a saturated C 2 -C g monocarboxylic acid,

b) at least one diisocyanate from the series tolylene diisocyanate, hexamethylene diisocyanate and EPDI (isophorone diisocyanate) and c) dimethylolpropionic acid (= 2,2-bis (hydroxymethyl) propionic acid),

the amounts of components a) to c) being chosen so that the molar ratio of the isocyanate groups of b) to the sum of the hydroxyl groups of a) and c)

0 5 to 1 05, preferably 0 8 to 1 0 and the molar ratio c / a 0 7 to 1 5, preferably 0 8 to 1 2 and the carboxyl groups originating from c) are at least partially neutralized

These polyurethanes III can, for example, be prepared in such a way that the

Reacting glycerol ester a) with the diisocyanate b) and the resulting addition compound with the diol c). The neutralization of the carboxyl groups of c) can take place before or after the reaction of c)

Suitable neutralizing agents include, for example, alkali and alkaline earth metal hydroxides, carbonates and hydrogen carbonates, such as sodium hydroxide, potassium hydroxide, sodium carbonate and hydrogen carbonate, potassium carbonate, magnesium, calcium and barium hydroxide, and also ammonia, primary and secondary amines with 1 to 30, preferably 3 to 18 carbon atoms, such as methylamine, ethylamine, n-propylamine, isopropylamine, n-butylamine, isobutylamine, hexylamine, cyclohexylamine, methylcyclohexylamine, 2-ethylhexylamine, n-octylamine, isotridecylamine, tallow fatty amine, stearylamine, oleylamine, dimethylamine , Diethylamine, di-n-propylamine, diisopropylamine, di-n-butylamine, diisobutylamine, dihexylamine, dicyclohexylamine, dimethylcyclohexylamine, di-2-ethylhexylamine, di-n-octylamine, diisotridecylamine, ditallow fat amine, distearylamine, distearylamine , Ethanolamine, diethanolamine, n-propanolamine,

Di-n-propanolamine and morpholine.

At least 50%, in particular at least 80%, of the carboxyl groups originating from c) are preferably neutralized

The reactions can take place in the absence or presence of organic solvents. Preferred organic solvents are inert to the starting compounds used and include, for example, acetone, methyl ethyl ketone, tetrahedral hydrofuran, dichloromethane, chloroform, perchlorethylene, ethyl acetate, dimethylformamide, dimethyl sulfoxide, N-methylpyrrohdon

The reaction of the compounds a) and b) can be catalyzed by cobalt naphthenate, zinc octoate, preferably dibutyltin dilaurate or dibutyltin diacetate, and by tertiary amines such as triethylamm or 1,4-diaza [2 2 2] -cycloctane

The polyurethanes III can be dispersed in water, for example by adding the neutralizing agent as an aqueous solution and removing any organic solvents which may be present. The polyurethanes III are expediently used as aqueous preparations with an ester urethane content of 1 to 40% by weight in an amount from 0.2 to 10% by weight, based on the shaved weight and polyurethane III solid

Polyurethanes III are excellent for the leather and make the leather hydrophobic and soft, as well as grain-resistant, without adversely affecting the colorability

Preferred auxiliaries based on natural substances III a) include casein, albumin, gelatin, protein breakdown products, starch, flour, chitosan, gum arabic, cellulose and derivatized (eg (partially) esterified) cellulose, lignin derivatives, vegetable tannins (if they are either biodegradable Form or in a subordinate amount so that they do not hinder the degradation of the leather), vegetable or animal fats (F Stather, "tanning chemistry and tanning technology", Akademie Verlag Berlin 1967, p 517 ff,), if necessary before, during or after tanning oxidized fatty substances,

Vegetable based fillers such as locust bean gum, guar, etc

Preferred polyesteramides III b) are known, for example, from US Pat. Nos. 4,343,931 and 4,529,792 and JP-A 79 1 19 593 and 79,119,594. Particularly preferred polyesteramides III b) are polymers which are aliphatic ester and aliphatic

Contain amide structures, the proportion by weight of the ester structures being 30 to 80% and the proportion of the amide structures being 70 to 20%. They preferably have an average molecular weight (M _w determined by gel chromatography in m-cresol against standard polystyrene) from 10,000 to 300,000, preferably 20,000 to 150,000

The starting products for the production of polyester amides III b) can come from the following groups

Dialcohols such as ethylene glycol, 1,4-butanediol, 1,3-propanediol, 1,6-hexanediol, diethylene glycol

and or

Dicarboxylic acids such as oxalic acid, succinic acid, adipic acid and others also in the form of their respective esters (methyl, ethyl, etc.)

and or

Hydroxycarboxylic acids and lactones such as caprolactone

and or

Amino alcohols such as ethanolamine, propanolamine

and or

cyclic lactams such as ε-caprolactam or laurolactam

and or

ω-aminocarboxylic acids such as aminocaproic acid

and or Mixtures (1 1 salts) of dicarboxylic acids such as adipic acid, succinic acid, etc. and diamines such as hexamethylene diamine, diaminobutane

Likewise, both hydroxyl- or acid-determined polyesters with molecular weights between 200 and 10,000 can be used as the ester-forming component

Preferred polyesteramides III b) can contain 0.01 to 5% by weight, preferably 0.1 to 2% by weight, based on the sum of all starting components, branching agents. Preferred branching agents include, for example, trihydric alcohols such as glycerol, trimethylolethane and propane, tetravalent alcohols such as pentaerythritol or tripasic carboxylic acids such as citric acid.

Preferred polyesteramides III b) contain built-in residues of divalent aliphatic C2-C12, preferably C2-Cg alcohols, aliphatic C2-C12, preferably C2-Cö-dicarboxylic acids, Cj-C ^ -, preferably C4-C6--amino carboxylic acids or cyclic lactams with 5-12, preferably 6-11 carbon atoms in the ring

The polyesteramides III b) can also be prepared with the aid of the 1 1 salt from aliphatic dicarboxylic acid and aliphatic diamine, for example the “AH salt” from adipic acid and 1,6-hexamethylene diamine

Preferred polyesteramides III b) contain 6-aminohexanoic acid residues as the amino carboxylic acid building block.

Polyesteramides III b) from ε-caprolactam, adipic acid and 1,4-butanediol are particularly preferred.

The polyesteramides III b) preferably have ester fractions of 35 to 65, in particular 35 to 55% by weight.

The synthesis of the polyesteramides III b) can be carried out by polymerizing the starting compounds at elevated temperature. The water of reaction can during or - preferably - distilled off after the reaction (in the latter case, if appropriate, together with excess monomers), if appropriate under reduced pressure. The starting compounds are statistically incorporated into the polymer.

The synthesis can be carried out either by the "polyamide method" by mixing the starting components, if appropriate with the addition of water and subsequent removal of water from the reaction mixture, or by the "polyester method" by adding an excess of diol with esterification of the acid groups and subsequent transesterification or transamidation of these esters. In this second case, the excess glycol is distilled off in addition to water.

The polycondensation can be accelerated by using catalysts. Both the known phosphorus compounds, which accelerate the polyamide synthesis, as well as acidic catalysts and salts such as oxides, acetates of Mg, Zn, Ca etc. for the esterification, as well as combinations of the two, are possible to accelerate the polycondensation.

The particularly preferred polyesteramides III b) are e.g. in the DE-OS

43 27 024.

The leathers produced according to the invention can be treated with preservatives based on thiocyanatomethylbenzthiazole or pyrocarbonates, e.g. Pyrocarbonate, are treated. The pyrocarbonates of

Advantage because in the presence of water they break down into the ecologically harmless components carbon dioxide and ethanol and no longer hinder later composting.

The invention further relates to leather which is biodegradable to at least 30% by weight in accordance with DIN 54 900, Part 3 (draft) and a shrinkage temperature, measured in accordance with DIN 53 336, of at least 65 ° C., preferably at least 70 ° C, especially at least 80 ° C. Molecular weights of polymeric compounds for the purposes of this invention are number average molecular weights (unless stated otherwise)

The percentages in the following examples relate to the

Weight

Examples

Resources used

BAYCHROM CP chrome tanning agent from Bayer AG medium reactivity for the BAYCHROM C process with 7.2% chromium oxide

BAYGENAL Grau S GL Acid Black 220 from Bayer AG

BAYGENAL Braun S RL Acid Brown 413 from Bayer AG

BAYMOL FD fl. 80% aqueous solution of a nonionic emulsifier from Bayer AG

BAYMOL AN 33% aqueous solution of nonionic emulsifiers from Bayer AG

CHROMOSAL B 33% basic chrome tanning agent with 25% chromium oxide from Bayer AG

CHROMOSAL BF 42% basic, weakly masked chrome tanning agent from Bayer AG with 25% chromium oxide

ENSUL AM 90 approx. 92%, sulfited, natural oil from Zschirmer and Schwarz, D-56112 Lahnstein

EUKANOL Schwarz D aqueous soot preparation from Bayer AG formed with the help of casein

EUREKA 800 FR blend of natural and synthetic oils from Atlas Oil, Newark NJ (USA) Magnesium oxide Magnesia 322 from Magnesia GmbH, Lüneburg

BAYGENAL Braun CGG Acid Brown 83 from Bayer AG

PRINOL F41 lubricant based on polymer and synthetic products from Zschirmer & Schwarz

LEVADERM medium brown chrome complex dye in ethoxypropanol

Bayer AG

LEVADERM brown chrome complex dye in ethoxypropanol from Bayer AG

LEVADERM Black-brown chrome complex dye in ethoxypropanol

Bayer AG

BAYDERM Finish DLF 40% polyurethane dispersion from Bayer AG

DEGRANIL DLN W 50 50% polyurethane dispersion from Bayer AG

EUDERM Mattierung SN Matting agent slurry in an aqueous preparation of

Bayer AG

BAYDERM Additive VL viscosity regulator based on PU from Bayer AG

EUDERM Fluid G leveling agent on aqueous, organic basis from Bayer AG

Quebracho, mimosa, chestnut commercially available vegetable tannins POLYZIM 202 proteolytic pickling agent based on pancreas from Diamalt, D-83064 Rauhling

PREVENTOL WB biodegradable preservative from Bayer AG

TANIGAN 3 LN lightfast, synthetic exchange and white tanning agent from Bayer AG

TANIGAN TF 2N organic, synthetic tanning agent from Bayer AG

TANIGAN OS organic, synthetic tanning agent from Bayer AG

Blocked polyisocyanate 1

168 g (1.00 mol) of hexamethylene diisocyanate are mixed with 25 g (0.05 mol) of polyether 2 (see below) at room temperature and heated to 100.degree. The temperature is held for 2 hours and then the NCO content is determined (calculated

42.4%, found 41.9%). After cooling to 15 ° C., 509 g (1.91 mol) of 39% aqueous sodium bisulfite solution are added and the mixture is stirred for 30 minutes, the temperature rising to approximately 45 ° C. Now the solids content is adjusted to 40% with 276 ml of demineralized water. After stirring for 7 hours at room temperature, a water-clear solution with a pH of 5.8 is obtained.

Polyether 2

500 molecular weight ethylene oxide polyether started on methanol with an ethylene oxide group content of 93.6%. Ester urethane 3

A heated, 500 ml three-necked round-bottom flask serves as apparatus, which is equipped with a stirrer, a reflux condenser with a drying tube and a dropping funnel

17.9 g of glycerol monostearate (0.05 mol) are placed in the flask. 45 mg of dibutyltin diacetate, 50 ml of anhydrous acetone and 14.72 ml (17.9 g) of tolylene diisocyanate-2.4 / -2.6 (ratio 80 / 20) (0.1028 mol) to The mixture is then heated to boiling for 30 minutes. Then 11.75 g of the triethylamine salt of 2,2-bis (hydroxymethyl) propionic acid (0.05 mol) are dissolved in 50 ml of anhydrous

Acetone, added dropwise within 10 minutes. After one hour of reflux, the formation of the ester urethane is complete. The solution is clear, moderately viscous and slightly yellow in color Vacuum distillation results in an approx. 17% clear solution of the ester urethane

Tanning agent 4

100 g of polysuccinimide with an average molecular weight M _w of 3000 are in

100 g of N-methylpyrrolidone with 69.5 g of stearylamine (0.25 mol / mol imide) at 140 ° C. The mixture is stirred at this temperature for 8 hours. The mixture is then cooled to room temperature. The reaction mixture is poured into excess (1500 ml) of methanol, the reaction product precipitating in fine particles. The product is filtered off with a suction filter and washed with methanol and dried. A light powder is obtained

100 g of the product obtained are placed in a solution heated to 80 ° C., which consists of 10 g of oleic acid, 4.3 g of monoethanolamine and 342.9 g of water. The dispersion is homogenized at 80 ° C for 60 minutes. The particle size is less than 500 nm. The dispersion is adjusted to a solids content of 25% by weight Polyurethane dispersion 5

83.4 g of a polyester of adipic acid, ethanediol and 1,4-butanediol in the weight ratio of ethanediol butanediol = 1.4 l of the molecular weight M _n 2000 and 3 g of a monohydric polyether alcohol of the molecular weight M _n 2240, produced by

Alkoxylation of n-butanol using a mixture of propylene oxide and ethylene oxide in a molar ratio of PO EO = 1 7, 1 is degassed together for 30 minutes at 120 ° C. and under vacuum. 0.1 g of benzoyl chloride and 13.7 g are added to the mixture under nitrogen Hexamethylene diisocyanate added in one pour. After stirring for 1 hour at 120 ° C., the NCO content is 2.84%. The prepolymer is dissolved in at 50 ° C.

300 g of acetone dissolved and at room temperature a mixture of 4.8 g of a 50% aqueous solution of the sodium salt of N- (2-aminoethyl) -2-amino-ethanesulfonic acid (AAS salt) and 1.15 g of ethylenediamine and 20 g of water were added After 15 minutes, 230 g of water are added and the acetone is removed at 60 ° C. and 140 mbar. 337 g of a thin, white dispersion remain with the distillation residue

30% polyurethane

example 1

Ashed bare is split to 2.2 mm. Then the bare is put into a usual one

Given the tanning keg and washed once with 200% (percentages here and below refer to the gap weight) water at 30 ° C for 10 minutes then the liquor is drained off In the subsequent decalcification, 30% water at 30 ° C, 2% Ammonium sulfate and 0.2% sodium meta-bisulfite added and agitated for 10 minutes. Then 0.2% formic acid (1 10 diluted) and 0.2% are added.

BAYMOL FD liquid and let run for 20 minutes. Staining is carried out in the same liquor for 30 minutes with 0.5% Polyzim 202. This results in a pH of 8.4 (sectioning the bare with phenolphthalein colorless). The liquor is then drained off

Wash twice with 150% water (from room temperature) and drain the liquor A quantity of leather is removed, which is processed further in accordance with Example 1 1. 30% of water at 30 ° C. is introduced into the tanning process which now begins, and 0.35% of magnesium oxide (Magnesia 322) and, after 60 minutes, 75% of the blocked polyisocyanate 1 are added After a running time of 5 hours, a pH of 7.1 is established, a further 0.35% magnesium oxide (Magnesia 322) is added and the mixture is left to run overnight (final pH 9.4), the next morning the resulting leather has a shrinking temperature of 78 ° C

The liquor is drained, the leathers are wound for 10 minutes at room temperature, then they are wilted and folded to a thickness of 1.0 mm

The folded leather is placed in a barrel and washed for 10 minutes with 200% water at 30 ° C (% - details relate to fold weight). The liquor is drained off

In a new liquor of 100% water, 40 ° C., 0.5% formic acid (diluted with water in a ratio of 1 4) is added. After 60 minutes, a pH of 4.8 is established

8.3% of the tanning agent 4 are then added to this liquor and left to run for 30 minutes. Then 2% ENSUL AM 90 are added and the mixture is left to run for a further 60 minutes, after which 4% of the ester urethane 3 is added. After a running time of 30 minutes, a mixture is added of 3% TANIGAN 3 LN and 3% sweetened chestnut and let this run for 40 minutes.

This is followed by a 40-minute pre-coloring with a mixture of 4% BAYGENAL Gray S-GL and 0.4% BAYGENAL Brown S-RL and pre-greasing in 30 minutes with 4% EUREKA 800 FR (diluted with water in a ratio of 1 4) if the liquor is increased by 100% with hot water at 50 ° C., let it run for 5 minutes and then add 2% formic acid (diluted with water in a ratio of 1 4). After a running time of 15 minutes, a pH of 4.9 is established

The liquor was then drained In fresh liquor of 100% water, 50 ° C, was greased with 8% EUREKA 800 FR (diluted with water in a ratio of 1 4) in 30 minutes. The liquor is drained In a new liquor of 200% water, 50 ° C, was then over-colored with 2% BAYGENAL S-GL and 0.2% BAYGENAL Braun S-RL in 30 minutes. A final pH of 20% was then added in 20 minutes by adding 1% formic acid (diluted with water in a ratio of 14) 3, 1 set. The liquor was drained and rinsed in the overflow for 5 minutes with water at 25 ° C.

The leathers were stored on the trestle overnight, then stretched wet, air-dried, air-conditioned, stolled, milled, stretched again and partly trimmed

Example 1.1 (comparison)

A part of the ashes, descaled and decalcified produced in Example 1 was tanned with mineral tanning agent as follows. For this purpose, the bare is in 20% water, 20 ° C, with 4% table salt (details based on the pelvis weight) for 5 minutes, with 0.5%

PREVENTOL WB (diluted with water in the ratio 1 2) for 10 minutes and treated with 1% sulfuric acid 96% (diluted with water in the ratio 1 10) for 60 minutes. A pH of 3.0 is established. 4.8% CHROMOSAL BF is added to the same liquor and agitated at intervals over a period of 8 hours over night. A pH of 3.7 is set. The liquor is drained off.

5 minutes in the overflow with 30 ° C warm water. Then you wilt the leather and fold to 1 mm

The leather is put back into the barrel and 100% water, 40 ° C. (% information from now on based on the shaved weight), 1% sodium formate and 1% sodium bicarbonate are added

After 45 minutes, the pH is adjusted to 4.9

Then add 4% CHROMOSAL B and after 20 minutes 4% ENSUL AM 90 (diluted with water in a ratio of 1 4). After a running time of 60 minutes the pH is adjusted to 4.2

The liquor is drained off and washed in 300% water, 40 ° C., 10 minutes. In fresh liquor of 100% water, 40 ° C., 4% of the ester urethane 3 are added After 30 minutes, 3% TANIGAN LN and 3% sweetened chestnut are added. After another 40 minutes, the pre-coloring with 2% TANIGAN FF-2N, 4% BAYGENAL Gray S-GL and 0.4% BAYGENAL Brown S-RL follows Pre-greasing takes place for 60 minutes with 4% EUREKA 800 FR (diluted with water in a ratio of 1 4). After 30 minutes, the liquor is washed with 100% water from

50 ° C increased After 5 minutes, 2% formic acid (diluted with water in a ratio of 1 10) is added in 2 installments within 15 minutes. A pH of 3.0 is established

The liquor is drained In a new liquor, 100% water, 50 ° C, the main greasing takes place with 8% EUREKA 800 FR (diluted with water in a ratio of 1 4) in 45 minutes. The liquor is drained

In a new liquor, 200% water, 50 ° C, 2% BAYGENAL Gray S-GL and 0.2% BAYGENAL Brown S-RL are over-colored in 30 minutes.

Formic acid (diluted with water in a ratio of 1 10) acidified to pH 2.9 in 30 minutes

The liquor is drained and rinsed with water at 25 ° C. for 5 minutes in the overflow. The leathers are deposited on the trestle overnight, then stretched wet, air-dried, air-conditioned, stolled, milled, stretched again and partly trimmed

Biodegradability test

The leather pieces to be tested were first dried to constant weight and then clamped in 6x6 cm slide frames. Compost from a composting plant was filled 2 cm high in plastic trays and the samples were placed in them. The filled trays were placed in an incubator for 4 weeks at 60, 50 and Incubated at 37 ° C Water losses were determined by weight loss and compensated for by adding distilled water. During the incubation, the pH of the compost was measured once a week. After 4 weeks, a batch was stopped, the samples were taken, cleaned, Dried to constant weight at 80 ° C and photographed Immediately after drying, the weight loss was determined by weighing again

A material was said to be degradable if, like the cellulose film used in a parallel test, it completely disappeared or showed clear signs of degradation

Leather 1 was completely degraded after 3 months, leather 1 1 only 5%

Example 2

A leather produced according to Example 1 is finished using the following method

Primer:

50 g EUKANOL Black D and 150 g polyurethane dispersion 5 are mixed with 500 g water. This mixture is sprayed onto the leather produced according to Example 1 (3 (cross) spray application (8/5/4 g / qfs)). Then another spray application ( 1 (cross) (4 g / qfs)), dried and ironed at 80 ° C with 200 bar for 6 seconds. Then again 1 cross (4 g / qfs) of the primer solution in

Spray process on

Finish:

100 g of casein solution (an aqueous solution is prepared from 13 g of casein with 8 g of aqueous ammonia and 79 g of water at 40 ° C.) are mixed with 30 g of polyurethane dispersion 5 and 500 g of water are added. One and a half cross (6 g / qfs) sprayed onto the primed leather. Then spray one and a half cross after a 10% aqueous formalin solution, dry, iron at 80 ° C and 150 bar

The leather thus treated withstood 20,000 wet kinks and 100,000 dry kinks (according to DIN 53 351) as well as 2,000 dry and 40 wet rubs (according to DIN 53 339) without damage Example 3

Coated split leather according to the invention, which are likewise biodegradable, can also be produced in an analogous manner

Tanning method

Retanning mode of operation

Coating

Air knife 0.04 mm solid support 15 g / m ² temperature 130-160-190 ° C

Squeegee gap 0.13 mm solid support 55 g / m ² temperature 130-160-190 ° C

Squeegee gap 0.18 mm solid support 55 g / m ² temperature 100-120-130 ° C

Claims

claims

1. Process for the production of leather, according to which

I. tanned (pre) with a) aldehydes or b) bisulfite-blocked polyisocyanates,

II. Optionally with the product obtained

a) polyaspartic acid, its salts and / or its anhydrides and / or

b) tanned polyaspartic acid amides,

III. a) the product obtained with polyurethane and auxiliary agents

Primed natural material base,

b) applying a finish made of polyurethane and / or polyester amide

and

IV. If necessary, the leather thus finished treated with a leather preservative.

Method according to claim 1, according to which the tanning agents and auxiliaries used are biodegradable to at least 30% by weight in accordance with DIN 54 900, part 3 (draft).

3. Leather obtainable by the process according to claims 1 and 2.

4. Leather that is biodegradable to at least 30% by weight according to DIN 54 900, part 3 (draft) and has a shrinking temperature according to DIN 53 336 of at least 65 ° C.

5. Leather according to claim 4, which have a shrinking temperature of at least 70 ° C.

6. Leather according to claim 4, which have a shrinking temperature of at least 80 ° C.

7. Articles, in particular clothing, shoes, seat covers, motor vehicle interiors, made of leather according to claims 3 to 6.