EP1530647B1 - Formulation for use in chrome or chrome-free tannage - Google Patents

Description

The invention relates to a formulation for use in chromium or chrome tanning, comprising a clay mineral and a use of clay minerals which are phyllosilicates.

In the tannery perishable animal skin substance is processed by preparatory treatment with so-called tanning aids, chemical reaction with tanning agents and appropriate dressing to resistant leather, which remains soft and supple and has the desired performance properties (see. Rompp Chemie Lexikon, 9th edition, 1995, page 1538 ). Hereby, the high water content stabilizing the collagen structure of the original skin substance is reduced and an irreversible stabilization by crosslinking by means of tanning agents is realized. A distinction is made between inorganic, mineral and organic-chemical tannins. Inorganic tanning agents are mainly chromium (III) salts, polyphosphates, aluminum, zirconium and iron salts. Organic tanning agents may be of synthetic or vegetable origin (see Rompp Chemie Lexikon, 9th edition, page 1541).

Inorganic polymers have hitherto generally been known in the tannery as fillers. After the in H. Herfeld: Library of the Leather, Volume 3, Umschau Verlag, Frankfurt, 2nd edition, 1990, page 227 inorganic fillers have no tanning effect. These include kaolin, finely divided clay ("China Clay"), colloidal silica, etc. These products are deposited in the loosely structured areas of the skin and preferably in the meat side. The influence of the scar pattern is very low, the Schleitbarkeit is often improved, the plush is shorter.

The disadvantage here, however, was the very loose binding or superficial incorporation into the skin substance. In subsequent process steps of leather production, for example, the so-called Millen, therefore, a significant proportion of the stored substances was released again and led to the clogging of the scars or to an abrasive damage to the grain image.

The DE-C 969689 describes the use of surface active siliceous fillers, in particular of silica and / or silicates in colloidally disperse form, with a particle size of 0.1 to 1 μ, for leveling, shortening and refinement the cut of in particular suede leathers. These silicium-containing colloidal dusts are to be strongly absorbed on the collagen fiber, whereby the storage should be largely retained during subsequent operations. However, colloidal disperse silica, silicates or mixtures thereof have the disadvantage of being subject to constant change as dynamic systems. As part of this change occurs during storage or during use of leather / leather goods by Ostwald ripening to a growth in size of the primary stored particles to sand-like agglomerates. As a result, abrasion of the leather is caused, for example, in shoe leathers by the flexing work in the collars. This so-called silicate tanning is therefore considered to be relatively unstable.

The specialist article by Y. Lakshminarayana et al. in JALCA, Vol. 97, 2002, pages 14 to 21 describes the use of bentonites for the preparation of graft polymers with methacrylic acid for use in the tannery, in particular in the aftertreatment of chrome-tanned leather.

The EP-A-0 007 555 describes the use of aluminum silicates with a particle size of 0.1 microns to 5mm with ester-containing carboxylic acid compounds in leather production.

In contrast, it was an object of the invention to provide a stable formulation comprising a clay mineral for use in the chromium or chrome tanning available that ensures improved properties of the resulting leather and an improvement of the process.

Accordingly, a formulation has been found for use in chromium or chrome tanning, comprising a clay mineral, the clay mineral being a phyllosilicate, having a number average particle diameter of less than 2 μm or a bimodal after stirring vigorously in water at 50 ° C for 30 minutes Size distribution with a first, finely divided fraction whose number average particle diameter is less than 0.5 microns and a second, coarser fraction whose number average particle diameter is less than 5 microns, respectively according to the determination method according to ISO 13320-1, by combined laser light diffraction and light scattering, wherein the proportion of the first, finely divided fraction is between 10 and 90% by weight, and one or more substances from one or more of the following groups: organic polymers, aldehyde tanning agents, sulfone tanning agents, resin tanning agents, phenol tanning agents, fatliquoring agents, vegetable tanning agents, dyes and pigment e.

It has surprisingly been found that the use of phyllosilicates which, after delamination by vigorous stirring in warm water, has a number-average particle diameter of less than 2 μm or a bimodal size distribution with a first finely divided fraction whose number-average particle diameter is less than 0.5 μm and a second, coarser fraction whose number-average particle diameter is less than 5 microns, wherein the proportion of the first, finely divided fraction is between 10 and 90 wt .-%, as tanning or for the production of tanning agents to a substantial improvement in the properties of the thereafter obtained Leather leads. For the delamination to determine the number average particle diameter, a treatment with a sufficient amount, usually about 950 ml of water based on 50 g of the clay mineral at 50 ° C and vigorous stirring, for example, 250 U / min, 30 minutes long required the clay mineral is dispersed in the water. This treatment is intended to ensure that the clay mineral is delaminated until the particle size no longer changes.

The determination of the particle sizes and particle size distribution was carried out according to ISO 13320-1 by combined laser light diffraction and light scattering with an analyzer from Malvern, type Malvern 2000.

It is believed that the interaction of the clay minerals with the above-defined particle sizes is essential to their interaction with the collagen chains of the skin. This interaction is possible, for example, via hydrogen bonding between collagen and the surface hydroxyl groups of the clay minerals. It has surprisingly been found that clay minerals with the defined particle sizes are irreversibly incorporated into the skin.

Clay minerals are weathering products of primary aluminosilicates, that is, of compounds with different proportions of alumina and silica. Silicon is tetrahedrally surrounded by four oxygen atoms, while aluminum is in octahedral coordination. Clay minerals are by far predominantly among the phyllosilicates also known as phyllosilicates or foliar silicates, but in some cases also to the band silicates (see Rompp Chemie Lexikon, 9th edition, 1995, pages 4651 and 4652).

For the formulations according to the invention, the clay mineral is a phyllosilicate. The phyllosilicate may preferably be a kaolinite, muscovite, montmorillonite, smectite or bentonite, in particular a hectorite.

Particularly good results are obtained by adding the clay minerals before or during their use as tanning agents with substances which, due to their chemical structure, are able to form strong hydrogen bonds with the clay mineral, in particular with urea or urea derivatives, alcohols, polyols, Propylene carbonate, organic amides, urethanes, saccharides or derivatives of saccharides, especially nitrocellulose, sulfite cellulose or ethylhexyl cellulose. Among other things, the delamination of the clay mineral, in particular phyllosilicate, is supported by this treatment.

Polymethacrylates, polyacrylates, maleic anhydride-styrene copolymers or maleic anhydride-isobutene copolymers can be used as organic polymers in the formulations according to the invention, for example.

Preference is given to formulations in which the phyllosilicate has a number-average particle diameter of less than 1 μm.

Particularly suitable is a formulation comprising a clay mineral, the clay mineral is a phyllosilicate, which after 30 minutes of vigorous stirring in water at 50 ° C, a number average particle diameter of less than 2 microns or a bimodal size distribution with a first, finely divided fraction whose Number average particle diameter, according to the determination method according to ISO 13320-1, by combined laser light diffraction and light scattering is less than 0.5 microns and a second, coarser fraction whose number average particle diameter is smaller than 5 microns, wherein the proportion of the first, finely divided fraction between 10 and 90% by weight, and the aldehyde tanning agent is glutaraldehyde or a derivative of glutaraldehyde, especially an acetal.

The invention also provides a use of phyllosilicates which after 30 minutes of vigorous stirring in water at 50 ° C a number average particle diameter of less than 2 microns or a bimodal size distribution with a first, finely divided fraction whose number average particle diameter is less than 0.5 μm and a second, coarser fraction whose number-average particle diameter is smaller than 5 μm, the proportion of the first, finely divided fraction being between 10 and 90% by weight, as tanning agents or for producing tannins.

Preferred is a use of phyllosilicates having a number average particle diameter of less than 1 micron.

It is advantageous to use the phyllosilicates before or during their use as tanning agents with substances which, owing to their chemical structure, are able to form strong hydrogen bonds with the clay mineral, in particular with urea or urea derivatives, alcohols, polyols, propylene carbonate, organic amides, urethanes, saccharides or derivatives of saccharides, in particular nitrocellulose, sulfocellulose or ethylhexylcellulose.

The clay mineral used is a phyllosilicate, more preferably a kaolinite, muscovite, montmorillonite, smectite or bentonite, in particular a hectorite.

The use can preferably be carried out by using the phyllosilicates as tanning agents or for the preparation of tanning agents for the pretanning, in particular for the chromium-free pretanning.

A further preferred use is characterized in that the phyllosilicates are used as tanning agents or for the preparation of chromium or chromium-free tannins for the retanning.

The following advantages are achieved with the formulations according to the invention and with the use according to the invention:

In particular, a significantly improved selective filling effect is achieved, that is to say loose, loose regions are preferably filled up, as a result of which an improvement in leather quality and surface yield is achieved.

The scar resistance is significantly improved, that is, the wrinkling or splitting at the surface is significantly reduced or avoided.

The leather quality is also enhanced by the improved embossability.

In addition, the leather quality is improved by increasing the tear strength.

An essential quality feature in the pretanning, especially in chrome-free leathers, is the ability to fold the semifinished product. This is improved by the invention, with the result of an improved surface texture and thickness of the folded skin and a reduced tool, in particular blade wear during the folding process. Significant is also the time gained through the improved process capability due to the reduced bonding of the folding blades.

According to the invention, the fat distribution of both native and applied fat is improved, resulting in a smoother, calmer surface. The improvement The levelness of the fat distribution also makes it possible to save up to 50% of the fatliquoring agent in the retanning and thus to provide particularly environmentally friendly tanning processes with a correspondingly low wastewater load.

An essential advantage of the process lies in the significant improvement of the environmental compatibility in that the liquor consumption, in particular with respect to the fatliquoring agent is improved by up to 50%, with correspondingly lower wastewater pollution.

The invention is explained in more detail below with reference to exemplary embodiments:

Examples B1.1 to B1.4 and comparative examples V1.0 to V1.4 pre-tanning wet white

The types of trade listed below under their brand names are products of BASF AG, Ludwigshafen.

Strengthened 1.6 to 1.8 mm split, pickled skin strips of 250 g each, together with 200 g of water at a pH of 3.0 and 25 ° C successively with 3% aqueous Glutardialdehyllösung (Relugan® GT 24) 60th min and then treated with 4% of the sulfone tanning agent Basyntan® SW. After a mixing time of 90 minutes, the mixture was blunted to pH 3.8 to 4.0 with a mixture of 2 parts by weight Tamol® NA and sodium formate.

In the comparative examples V1 to V1.4 and Examples 1.1 to 1.4, 10 g of the clay minerals listed in Table 1 below were added to the liquors together with the glutaraldehyde solution. The average particle sizes of the clay minerals were determined by laser diffraction / light scattering on freshly prepared suspensions with a solids content of 5% in each case according to ISO 13320-1.

After pre-tanning, 100 g of each liquor were coarsely filtered through a 25 μm sieve filter. The remaining solids content was sedimented in a centrifuge and weighed after washing and drying.

Punkt 4.1:

Die Probestücke hatten die Abmessungen 3 cm · 1 cm, die Dicke wurde nicht bestimmt;

Punkt 4.2:

es wurde nur eine anstelle von 2 Proben pro Ledermuster geprüft;

Punkt 6:

entfiel;

Punkt 7:

die Trocknung im Vakuum-Exsikkator entfiel und

Punkt 8:

bei Rückgang des Zeigers wurde die Schrumpfungstemperatur abgelesen.

Tabelle 1 Tonmineral Mittlere Teilchengröße Feststoffanteil Flotte Falzbarkeit Schrumpf-temperatur [µm] [g] [Note 1- 5] [°C] V 1.0 - - - 3 79 V 1.1 Kaolin 13,2 3,8 3,5 77 V 1.2 Kaolin 7,6 2,9 3 78 V 1.3 Kaolin 5,1 2,7 2,5 78 V 1.4 Kaolin 3,2 1,4 2,5 79 B 1.1 Kaolin 1,3 0,55 1,5 81 B 1.2 Montmorillonit 0,6 0,30 1 83 B 1.3 Kaolin/ Montmorillonit bimodal 0,6 / 3,2 0,7 1 82 B 1.4 Kaolin/Bentonit 0,2 / 1,3 0,35 1 82 Table 1 below shows the solids content of the liquor after the tanning process, based in each case on the original total liquor. The folding ability of the pre-tanned leather was assessed on a grading scale of 1 to 5. The shrinkage temperature was determined according to DIN 53336, which was modified in the following points as follows:

Point 4.1:

The specimens had the dimensions 3 cm x 1 cm, the thickness was not determined;

Point 4.2:

only one sample per leather sample was tested instead;

Point 6:

accounted for;

Point 7:

the drying in the vacuum desiccator accounted for and

Point 8:

as the pointer dropped, the shrinkage temperature was read.

Table 1 clay mineral Mean particle size Solids content fleet shaveability Shrink temperature [.Mu.m] [G] [Grade 1-5] [° C] V 1.0 - - - 3 79 V 1.1 kaolin 13.2 3.8 3.5 77 V 1.2 kaolin 7.6 2.9 3 78 V 1.3 kaolin 5.1 2.7 2.5 78 V 1.4 kaolin 3.2 1.4 2.5 79 B 1.1 kaolin 1.3 0.55 1.5 81 B 1.2 montmorillonite 0.6 0.30 1 83 B 1.3 Kaolin / montmorillonite bimodal 0.6 / 3.2 0.7 1 82 B 1.4 Kaolin / bentonite 0.2 / 1.3 0.35 1 82

The comparison of the results of the comparative experiments V1.0 to V1.4 and the examples according to the invention B1.1 to B1.4 shows a significant reduction of the solids content in the liquor after the tanning process (fourth column in Table 1), that is a clear Improvement of Fleet wasting, as well as an improvement of the hemmability (5th column) and the shrinkage temperature (last column).

Comparative Examples V2.0 V2.1 and Examples B2.1 and B2.2 retanning wet blue upper leather

A commercially available Zebu wetblue leather was folded and quartered to a thickness of 1.8 to 2.0 mm. Subsequently, the quarters were in a barrel and a fleet length of 200%, that is, a liquor of 2 kg aqueous phase to 1 kg of leather at intervals of 10 minutes with 2% sodium formate and 0.4% sodium bicarbonate and 1% Tamol® NA added. After 90 minutes, the fleet was drained and the Zebu district distributed to four separate walk barrels.

In Comparative Example 2.0, a 1% aqueous solution of the dye Luganil® Braun was metered at 25 ° C in one of the Walk barrels and then the Zebu quarter in the barrel for 10 min walalkt.

Thereafter, 3% Relugan® RV polymer tanning material, 5% sulfone tanning agent Basyntan® DLX and 2% Resin Tanning Relugan® DLF were added and tumbled again at 10 rpm for 20 minutes.

Thereafter, the skin was treated with 3% commercial vegetable tanning material Mimosa for 40 minutes and then treated with 2% vegetable tanning material Mimosa for a further 40 minutes.

It was then acidified to pH 3.6 to 3.8 with formic acid. After 20 minutes, the liquor was drained and washed with 200% water. Finally, 5% Lipodermlicker® CMG and 2% Lipodermlicker® PN were dosed in 100% water at 50 ° C. After a flexing time of 45 min, it was acidified with 1% formic acid.

The washed leather was dried and staked, and the quality was evaluated in terms of fullness, grain firmness, softness and levelness / fatness according to grading from 1 (very good) to 5 (unsatisfactory). In addition, the tensile strength in Newton were determined according to DIN 53328 and the puncture breaking strength in Newton according to DIN 53331. The comparison of the values for the S c hemischen oxygen b NEEDS (COD values) confirms the improved liquor exhaustion with the inventive clay minerals.

In Comparative Example 2.1, compared with Comparative Example 2.0, together with the sulfone tanning agent Basyntan® DLX, a clay mineral according to Comparative Example 1.1, that is kaolin with a further particle size of 13.2 μm, in a concentration of 4%, was metered in.

In contrast, 4% of the clay minerals according to Examples B1.1 and B1.4 were respectively added in Examples B2.1 and B2.2.

Table 2 below shows a significant quality improvement in terms of fullness, grain firmness, softness, dyeing / greasing levelness and tensile strength and Stichausreißkraft the obtained in Examples B2.1 and B2.2 according to the invention over the Comparative Examples V2.0 and V2.1 leather. Table 2 clay mineral wealth Scars firmness softness Tensile strength [N] Tear-out force [N] Egality / Coloring / Greasing COD [mg O ₂ / I fleet] V 2.0 - 3 3.5 3 428 302 3 16200 V 2.1 V 1.1 3 3 3.5 410 292 2.5 14800 B 2.1 B 1.1 2 2.5 2 452 319 1 10700 B 2.2 B 1.4 1.5 2 2.5 449 328 1.5 6900

Comparative Examples V3.0 to V3.2 and Examples 3.1 to 3.3 retanning wet white furniture leather

The skin of a southern German bovine was converted into a wet white semi-finished product, folded to a thickness of 1.2 mm and cut into strips of about 250 g each.

In Comparative Example C3.0, the skin was treated with 150% water over 40 minutes at 35 ° C with 3% Relugan® GT 50, that is, a formulation comprising essentially an aqueous glutaraldehyde solution and 0.5% formic acid. Subsequently, it was treated for 60 minutes with 4% of a mixture consisting of equal parts of Tamol® NA and sodium formate and then drummed with 4% Relugan® SE and 5% Basyntan® SW, ie a sulfone tanning agent, over 20 min. Thereafter, 6% of the commercial vegetable tanning agent Tara and 2% resin tanning Relugan® S and 2% dye Luganil® Braun NGB were added and the mixture was rebalanced. After 2 h, the pH was adjusted to 3.6 with formic acid. 6% Lipodermliquor® CMG and 1% Lipamin® OK were added as fatliquoring components. After a drumming time of a further 60 minutes, the mixture was acidified again to pH 3.2 with formic acid and, before the liquor was discharged, samples were taken to determine the solids content thereof, that is to say, the fleet wastes. The leathers were washed twice with 100% water, stored moist overnight and dried after tentering on tenter at 50 ° C.

The liquor consumption and the quality of the leather in terms of fullness, grain firmness, softness, levelness and embossing were rated according to a grading system from 1 (very good) to 5 (unsatisfactory). The evaluation of the liquor was done visually according to the criteria residual dye (extinction) and turbidity (fatliquoring agent). To judge the Embossing the pieces of leather were treated according to the following procedure: Prepared and pressed with a platen press at a pressure of 120 bar and a temperature of 80 to 100 ° C for 5 sec. The quality of the embossing was measured according to the criteria embossing depth, levelness and reminiscence after tensile load.

In Comparative Example V3.0 no clay mineral was added, in Comparative Example C3.1 the clay mineral corresponding to V1.1, ie kaolin with a mean particle size of 13.2 μm and in Comparative Example C3.2 the clay mineral according to Comparative Example C1.3, ie Kaolin with a mean particle size of 5.1 microns.

In example B3.1, the clay mineral according to example B1.1 was added, that is to say a kaolin having the average particle size of 1.3 μm, in example 3.2 a clay mineral corresponding to example B1.2, that is to say montmorillonite having the average particle size of 0, 6 μm and in Example B3.3 the clay mineral according to Example B1.3 ie a mixture of kaolin and montmorillonite having a bimodal mean particle size distribution, one fraction having an average particle size of 0.6 μm and a second fraction having an average particle size of 3, 2 microns had. Table 3 Clay mineral Fleet-Off consumption wealth grain tightness softness Tensile strength [N] Stitch break force [N] levelness embossing V 3.0 - 3.0 3 3.5 3 268 192 3 3 V 3.1 V 1.1 4 3 3 3.5 248 188 2.5 3.5 V 3.2 V 1.3 3.5 2.5 2.5 3 259 194 2 3 B 3.1 B 1.1 2.5 2 2.5 2 277 201 1 2.5 B 3.2 B 1.2 2 2 1.5 2 284 223 1 1.5 B 3.3 B 1.3 1.5 1.5 2 2.5 289 218 1.5 1.5

The comparison of the results of Comparative Examples V3.0 to V3.2 and the examples according to the invention B3.1 to B3.3 in Table 3 shows an improvement in all quality characteristics, ie fullness, grain firmness, softness, tensile strength, puncture breaking strength, levelness , Embossing as well as in the Fleet consumption.

Claims (11)

1. A formulation for use in chrome-free or chrome tanning, comprising a clay mineral, the clay mineral being a phyllosilicate, which, after vigorous stirring for 30 minutes in water at 50°C, has a number average particle diameter of less than 2 µm or a bimodal size distribution with a first, finely divided fraction whose number average particle diameter is less than 0.5 µm and a second, coarser fraction whose number average particle diameter is less than 5 µm, determined in each case by the method according to ISO 13320-1, by combined laser light diffraction and light scattering, the amount of the first, finely divided fraction being from 10 to 90% by weight, and one or more substances from one or more of the following groups: organic polymers, aldehyde tanning agents, sulfone tanning agents, resin tanning agents, phenol tanning agents, fatliquoring agents, vegetable tanning agents, dyes and pigments.
2. The formulation according to claim 1, wherein the aldehyde tanning agent is glutaraldehyde or a derivative of glutaraldehyde, in particular an acetal.
3. The formulation according to either of claims 1 and 2, wherein the clay mineral has a number average particle diameter of less than 1 µm.
4. The formulation according to any of claims 1 to 3, wherein substances which, owing to their chemical structure, are capable of forming strong hydrogen bridge bonds with the clay mineral, in particular urea or urea derivatives, alcohols, polyols, propylene carbonate, organic amides, urethanes, saccharides or derivatives of saccharides, in particular nitrocellulose, sulfite cellulose or ethylhexylcellulose, are added to the clay mineral before or during the use thereof as a tanning agent.
5. The formulation according to any of claims 1 to 4, wherein the phyllosilicate is a kaolinite, muscovite, montmorillonite, smectite or bentonite, in particular a hectorite.
6. The use of clay minerals which are phyllosilicates and which, after vigorous stirring for 30 minutes in water at 50°C, have a number average particle diameter of less than 2 µm or a bimodal size distribution with a first, finely divided fraction whose number average particle diameter is less than 0.5 µm and a second, coarser fraction whose number average particle diameter is less than 5 µm, the amount of the first, finely divided fraction being from 10 to 90% by weight, as tanning agents or for the preparation of tanning agents.
7. The use according to claim 6, wherein the clay minerals have a number average particle diameter of less than 1 µm.
8. The use according to claim 6 or 7, wherein substances which, owing to their chemical structure, are capable of forming strong hydrogen bridge bonds with the clay mineral, in particular urea or urea derivates, alcohols, polyols, propylene carbonate, organic amides, urethanes, saccharides or derivatives of saccharides, in particular nitrocellulose, sulfite cellulose or ethylhexylcellulose, are added to the clay minerals before or during the use thereof as tanning agents.
9. The use according to any of claims 6 to 8, wherein the phyllosilicate is a kaolinite, smectite, muscovite, montmorillonite or bentonite, in particular a hectorite.
10. The use of clay minerals according to any of claims 6 to 9, wherein the clay minerals are employed as tanning agents or for the preparation of tanning agents for preliminary tanning, in particular for chrome-free preliminary tanning.
11. The use of clay minerals according to any of claims 6 to 9, wherein the clay minerals are employed as tanning agents or for the preparation of chrome or chrome-free tanning agents for retanning.