CH647259A5 - METHOD FOR TANNING ANIMAL SKIN AND SKIN WITH IRON SALT. - Google Patents

Description

The present invention now relates to a process for tanning animal hides and skins with iron salts, which is characterized in that the tanning is carried out with powdery tanning agents from divalent iron salts and aliphatic oxycarboxylic acids or their salts. The present invention furthermore relates to such tannins in powder form for carrying out the process according to the invention, characterized in that they contain bivalent iron salts and aliphatic oxycarboxylic acids or their salts, and finally the animal hides and skins tanned according to the invention. The present invention furthermore relates to the combined chromium-iron-II tanning with the tanning agents according to the invention, i.e. that the tanning is carried out using additional tanning chromium salts.

The organic oxyacids or their salts have a masking influence. Tartaric acid is particularly well suited. Gluconic acid, too, especially in the form of its Na salt, has a good effect.

Good results are achieved with a mixture of these two agents. Citric and malic acid, glycolic acid and lactic acid as well as gluconic acid 3-lactone also have a masking effect.

The amount of iron (II) salts for the tanning to be carried out depends on a number of factors, such as the origin and nature of the pale to be tanned, the type of leather desired and, above all, the type of iron compound used and the associated masking agent according to the invention . A particularly good agent in the sense of the present invention is FeS04 in the form of its water of crystallization.

Based on the weight of the pimples, between II and 20%, preferably about 10-15%, and between 2 and 20%, preferably about 3 and 10%, of masking agents are usually used in ferrous salts. The preferred powdered tanning agents contain the compounds in the ratio of the above. Amounts.

As already w.o. However, the amount of tanning agent, such as the ratio of iron (II) compound to masking agent, depends on the respective fur and so the above Values are both exceeded and undershot.

For a preferred system of iron-II-sulfate (with 7 H2O as water of crystallization) and tartaric acid, the following amounts are optimally used, depending on the sheer:

Fe S04 x 7 H2O

Tartaric acid

Sheep and lambskins approx. 12.00%

3.2%

Goat and kid skins

12.00%

3.2%

Pigskins

16.00%

4.3%

Veal and beef skins

16.00%

4.3%

(The values given are only averages, which can vary up and down depending on the origin of the blossoms by several orders of magnitude.) The suitable powder mixture contains about 3-5 parts of the iron salt to a part of acid. The mixture preferably contains 4 parts of the salt to one part of acid.

The tanning process is preferably carried out in a known manner as for tanning with chrome tanning powder. First, the powder in the pickled state is mixed with the powder mixture of FeS04 x 7H2O and tartaric acid (however, previous dissolution in water and addition in this form is also possible). Depending on the concentration, temperature, number of revolutions of the barrel and the thickness of the material, the small-scale iron II compound penetrates the skin in about 1-4 hours. The pH is then increased to about 4.2-4.8 by adding soda. The number of sulfato groups in the complex is reduced and OH groups are introduced into the complex. This promotes the formation of multinuclear complexes, the individual particles are enlarged and the tanning effect is increased.

After tanning has ended, storage for several days (2-3 days) further increases the bond to the skin and thus the tanning effect.

The following examples serve to illustrate the invention. Parts are parts by weight or parts by volume,% are given in% by weight. All percentages refer to the weight of the pimples.

example 1

To three degreased sheep pimples with a weight of 2300 g are added in a glass barrel of 60 cm diameter and 10 revolutions per minute with 100% saline solution at 5% 30 ° C, in the same bath comes 1% of an amphoteric sulfo-containing fatty acid derivative (commercial product, eg Tergolix A); after running for 10 minutes, 0.8% formic acid 85% and 0.1% sulfuric acid conc. You continue to run for 30 minutes. The final pH is 1.7.

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Then 15% of an intimate mixture of 790 parts of FeSCh x 7H2O (dewatered) and 210 parts of tartaric acid are added in powder form. After 2 hours of running, the final pH is 1.8. 5.5% soda calc. (1:20 diluted with water) slowly added dropwise within 2 hours, the final pH is 4.9. After running for 1 hour, leave it in the bath overnight and continue for 1 hour in the morning. The pH is 3.8. After adding another 0.5% soda calc. (1:20 diluted with water) within 15 minutes by slowly adding drops, let it run for another 1 hour. The final pH is now 4.2.

The skins are stored for 3 days and have a light yellow-green color when wet. The hot water sample at 90 ° C (1 minute) shows no shrinkage. The leathers are then wilted (dewatered) and folded (leveled to the same thickness).

The following percentages now refer to the fold weight. For neutralization, coloring and greasing, the tanned skins are first washed with 500% water at 30 ° C for 10 minutes. The mixture is then run with 300% water at 30 ° C. and 1% sodium formate for 60 minutes (final pH in the bath 4.9). The cut of the leather with bromocresol green is blue-green. For coloring, 300% water (40 ° C) and 2% of a commercially available anionic fatty acid derivative (e.g. Sandolix WW) and 3% of the dye C.I. acid brown 362 added and allowed to run for 45 minutes. 1% formic acid 85% is added and the mixture is left to run for a further 15 minutes.

It is then washed with 500% water at 30 ° C. for 15 minutes. The greasing is carried out with 300% water at 50 ° C and each with 4% of a commercially available sulfated fish oil (e.g. Sandolix O) and an emulsion of a commercially available anionic synthetic fat derivative (e.g. Sandolix SE). The running time is 60 minutes. Then 85% is acidified with 1% formic acid. Finally, it is washed with 500% water at 30 ° C. for 5 minutes. After a deposit on the trestle, the leather is wilted (dewatered), stretched (smoothed on the grain side) and dried.

After drying, the leather is placed in damp sawdust, rolled (softened) and tensioned.

Leather with good fullness, level coloring, very good softness and good coloring are obtained.

Example 2

A pickled half beef pellet with a weight of 3200 g is treated in a glass barrel 60 cm in diameter and 8 revolutions per minute with 100% saline solution 5% 20 ° C. for 10 minutes, then 0.2% sulfuric acid is added and the mixture is run for 40 minutes left (final pH 1.6).

Then 20% of a powdery mixture of 790 parts of FeSC> 4 x 7H: 0 (dewatered) and 210 parts of tartaric acid are added and the mixture is left to run for 4 hours (final pH 1.7).

After portionwise addition of 5.0% soda (diluted 1:20 with water) in 5 portions at intervals of 30 minutes by slow dropping, the mixture is left to run for 1 hour (final pH 4.2). The mixture is left in the bath overnight, the next morning it is left to run for 30 minutes (final pH 3.9).

1.5% soda (diluted 1:20 with water) are slowly added dropwise within 1 hour and then run for another 1 hour (final pH 4.8).

After 3 days of storage, the leather has a light yellow-green color when wet and the hot water test at 90 ° C does not show any shrinkage. The leather is wilted and folded after the specified duration.

For neutralization, coloring and greasing, the leather is first washed with 500% water at 30 ° C for 10 minutes. It is then treated with 300% water at 30 ° C. and 0.8% sodium formate for 30 minutes (final pH bath 4.8). The cut of the leather with bromocresol green is blue-green on the outside and yellow on the inside. It is then washed with 500% water at 30 ° C. for 10 minutes, after which the dyeing takes place. This is done with 300% water at 40 ° C, 2% of a commercially available anionic fatty acid derivative (see example 1) and 1% of the coloring agent C.I. Acid Brown 362 run for 30 minutes.

Acidify with 0.5% 85% formic acid (1:10 diluted with water) within 15 minutes. The greasing takes place with 300% water at 40 ° C and the auxiliaries specified in Example 1 (equal amounts) within 45 minutes. 15 The acidification is carried out with 0.5% formic acid for 10 minutes, and finally it is washed with 500% water for 5 minutes.

After drying, the leather is placed in damp sawdust, rolled (softened) and tensioned.

20 A leather with good fullness and with a firm grip is obtained.

Example 3

All percentages refer to the weight of the pimples 25. 2 sheep picks, degreased, with a weight of 1500 g are placed in a glass barrel of 60 cm diameter and 10 revolutions / min. placed in 100% 5% saline at 30 ° C, then run for 10 minutes. 20% of a mixture of 819 parts of FeSC> 4-7H20, 74 parts of tartaric acid and 107 parts of sodium gluconate are then added in powder form and the mixture is left to run for 2 hours, the final pH here being 2.0. Then add 6% soda, 1:20 diluted, in 5 portions every 30 minutes. Then let it run for another 2 35 hours, the final pH is 4.5. The skins are placed on the goat. The hot water sample, 1 hour after tanning at 90 ° C, 1 minute, shows no shrinkage.

40 Example 4

All information refers to the weight of the naked woman.

2 halves of beef with a weight of 7200 g are descaled, pickled and pickled like normal chrome tanning. The tanning is then started with 3% of a 45 commercially available chrome tanning agent (with 26% chromium oxide and 33% basicity); after a two-hour runtime, 8% of a mixture of 790 parts of FeS04-7HaO, is dewatered, and 210 parts of tartaric acid are added. After a further 2 hours of running, 3% soda, 1:20 diluted, is slowly added dropwise within 50 hours. The mixture is left to run for a further 2 hours, the final pH is 4.6. The beef halves are placed on the goat. The hot water sample, 1 hour after tanning at 90 ° C, 1 minute, shows no shrinkage.

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Example 5

All percentages refer to the dry weight of the furs. 2 Australian lamb skins weighing 620 g are soaked, fleshed, washed and 60 pounded as usual. After the pimples they are deposited for a day, then the tanning takes place. The skins are placed in a bath of 2000% water at 35 ° C, 50 g / 1 table salt and 0.5 g / 1 of an amphoteric, sulfo-containing fatty acid derivative (commercial product, e.g. Tergolix A). After 20 minutes of running, 16 g / l of a mixture of 790 parts of FeS04-7H2O, dewatered, and 210 parts of tartaric acid 1: 4 dissolved in water at 25 ° C. are added.

After 2 hours of running, 4 g / 1 of a cationic

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polyglycolated aliphatic ester amide (commercial product, e.g. Katalix GS) added in aqueous emulsion. After running for two hours, blunt with 5.0 g / 1 sodium bicarbonate. This is slowly added in 5 portions

30 minutes apart. Then let it run for 1 hour.

The skins are then deposited for 1 day. The hot water sample 80 ° C for 1 minute shows no shrinkage.

B

Claims (5)

647259 1. A process for tanning animal hides and skins with iron salts, characterized in that the tanning is carried out with powdery tanning agents from divalent iron salts and aliphatic oxycarboxylic acids or their salts. 2. The method according to claim 1, characterized in that tartaric acid, citric acid or gluconic acid or salts thereof are used as oxycarboxylic acid. 2nd PATENT CLAIMS 3. The method according to claims 1 and 2, characterized in that the tanning is carried out using additional tanning chromium salts. 4. The animal hides and skins tanned by the process according to one of claims 1-3. 5. Tannins in powder form for carrying out the method according to claim 1, characterized in that they contain divalent iron salts and aliphatic oxycarboxylic acids or their salts. The present application relates to a tanning process using solid tanning agents which contain powdered iron (II) salts and masking agents for the production of leather, and to the corresponding tanning agents. So far, only iron III salts have been used in practice for tanning purposes and it has been claimed for iron II salts that they are not suitable as tanning agents at all. It is known from French patent specification 881 676 that iron (II) salts have a tanning effect. According to the description and the only example of this patent specification, only liquid tanning with iron (II) salts is described. According to the specifications in this patent, tartaric acid or citric acid can be used as agents which are also used in the tanning with iron (II) salts. According to the example, however, the tanned leather is oxidized in the air. Surprisingly, iron II tanning has never been mentioned since FR-PS 881 676, and it was even claimed in a dissertation in 1947 that iron II salts had no tanning effect. In the past, according to the publication of FR-PS 881 676, only the so-called “Ferrigan” tanning process with iron III salts was able to assert itself as the only iron tanning.