DE1469017A1 - Process for tanning hides and skins - Google Patents

Description

ZEILSTOPPPABRIK WALDHOP Mannheim, July 10, 1968

Dr.vdB./K. IO.N.432)

Actζ.Ρ U 69 017.6

Process for tanning hides and pelts.

The development of tanning processes with synthetic tanning agents led to the most varied attempts to investigate the tanning effect of these Improve fabrics. In order to obtain usable leathers and pelts, it is necessary in every pail that the tanning agents are used once penetrate the goods to be tanned as evenly as possible and, on the other hand, so that they are so firmly embedded in the skin, that they can no longer be washed out of the finished leather or pellet.

Synthetic resins that can be used for tanning purposes generally tend to undergo polymerization or condensation reactions, whereby the formation of higher molecular weight products is absolutely valuable or necessary for good adhesion in the leather. Important This is particularly the case in the production of outsole and insole leather, which is particularly stressful in this regard is exposed and should have a high welding strength.

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Documents (Art. 7 il para. I No. 1 sentence 3 of the amendment act. V. 4.9.196 "//

For this purpose, attempts have already been made in various ways to introduce substances of higher molecular weight into the skin to facilitate. It is known, condensed or precondensed products, for example from urea and formaldehyde, or a To bring geiaiscn of the individual condensation partners into the skins and to carry out condensation or final condensation within the skin. With simultaneous introduction of the However, there is a risk of reactants that the condensation reaction begins too early, i.e. partial condensation reactions between the partners occur before the skins are completely soaked in the solution.

From the patent 1 005 234 a method was known in which the skin is first treated with an aqueous solution of a lignin derivative,

an aldehyde and an acid diamide was soaked »Subsequently the three condensation partners within the tanned material were flocculated by lowering the pH. However, this method requires strict adherence to the pH values in order to prevent a premature condensation reaction outside of the tanned material. In addition, the required pH values must be determined through preliminary tests. This The procedure is therefore cumbersome and requires precise monitoring measures, in addition, the were received after this procedure leather is relatively hard and brittle and has a strong tendency to shrink, especially at elevated temperatures.

It has now been found that leather and hides with surprisingly good properties, especially for use as running, Putter and insole leather, if you have hides

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or skin is subjected to tanning by condensation of ligninsulphonic acid and / or its salts, amino compounds and aldehydes within the animal skin. It was recognized as essential that first the lignin derivative is incorporated into the skin, then the monomeric amino compounds are introduced together with the aldehydes and then the condensation in a known manner by setting the pH value below 7, preferably below 2 , he follows.

It has been shown that it is absolutely necessary to first treat the skins or pelts only with the ligninsulphonic acid or its salts, namely during the pimples, in order for the tanning agent to penetrate completely into the interior of the skin, even between the veins to ensure. The lignosulfonic acid can be used both as a free acid and in the form of its salts, such as the sodium, potassium, ammonium, calcium, magnesium, aluminum, titanium, zirconium, chromium salt, or mixtures of these salts or mixtures of the free acid can be used with salts. Particularly advantageous results are achieved if the lignosulfonic acid contains a small proportion of cationically bound chromium, with a chromium content of less than 3% (calculated as Cr ₂ O) being sufficient.

The amino compounds used for the process according to the invention are urea, thiourea, methylenediurea, cyanamide, guanidine, Alkylguanidines, dicyandiamide, dicyandiamidine and triazine derivatives, such as ammeline, ammelide, guanamine and melamine in embossing, preferably urea, dicyandiamide and melamine. Desired In any case, mixtures of the amino compounds,

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for example dicyandiamide and melamine, are used. "However, analog connections that contain at least one contain reactive amino groups, are used

Formaldehyde and / o * acetaldehyde are preferred as aldehydes. However, other saturated, aliphatic aldehydes can also be used.

The amount of aldehydes required is $ 1-6, preferably no more than $ 3 calculated on the weight of the nakedness. Of amino compounds Generally amounts of about $ 3-10, preferably 4-6 # required.

The leathers produced according to the invention are, on the one hand, distinguished by a special color and lightfastness on the other hand also particularly flexible and have a very high

Abrasion resistance. Particularly noteworthy is her low specific weight and good resistance at higher temperatures.

Raise the good properties of those obtained by this process The tearing process according to the invention has the great advantage of being carried out very quickly and nevertheless very effectively for leather or hides become to kötlnen.

The course of the method according to the invention is as follows explained in more detail

The pelts, pelts prepared in the usual way, for example from BuIIe ₁ beef, calf, goat, sheep, lamb, etc., and pelts from, for example, foals, lamb, rabbits, hot game, and ■

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Noble skins are placed in an acid pick and kept in constant movement for about 1-3, preferably 2 hours. Then the pimple broth is lignin sulfonic acid and / or its salts, preferably a chromium lignosulfonate, in an amount of 5-20 $, Preferably 10-159% calculated on the nakedness, admittedly. With This mixture is kept in the drum for a few hours, preferably 4-6 hours, with constant movement. The lignin sulfonic acid can easily penetrate the skin and is partly held there by chemical bonds. To Withdrawing the pickle broth, the tanned material is rinsed, which is now suitable for taking up the two other condensation partners is. The addition of the amino compounds Xmd of the aldehydes takes place in a relatively concentrated solution, about 20 to 100 ^

preferably $ 30-40 of the liquor so that both chemicals are absorbed by the skin very quickly. This has proven to be. expediently shown the temperature of the liquor between 20 and 60 ° to hold preferably between 30 and 45 ⁰ C. A particularly preferred embodiment provides that ligninsulphonic acid and / or its salts, here preferably its alkali or alkaline earth metal salts, are also used in an amount of 2-1 often, preferably 4-6 $ (calculated on the lump weight). After about half an hour to two hours, preferably after an hour, the solution is adjusted to a pH value below 7, preferably below 2, by means of acid, preferably hydrochloric acid, and drummed for another half to two hours, preferably one hour. This completes the tanning process, which - as the following examples show - only takes a few hours. The leather is then finished in the usual way

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Examples:

1.) Decalcified beef pelts are first lightly pickled in a known manner and then picked for one hour at 1007 ° liquor with 4% sodium chloride, 4% sodium sulfate, 0.5% hydrochloric acid and 0.1% formic acid. Then 10 $ of a chromium lignin sulfate, which contains 3% Cr ₂ O. * chemically bonded, is dissolved in the pimple and treated with movement for 4 hours. The barrel then stays there overnight. After the broth has been drained off, it is rinsed briefly, after which 30% water, 5% urea and 5% calcium lignin sulfonate (50%) are added. The barrel runs at 40 ^° C. for 20 minutes. Thereafter was added (29% strength) 10 $ Formalsdehyd treated for one hour at 40 ⁰ C, then treated with hydrochloric acid (36% strength) to a pH value of 1 acidified and treated again one hour. Then the leather is finished in the known way "It is hung on the trestle overnight, then neutralized, lightly greased and dried · The result is a very light yellow, flexible sole material with a low specific weight and very high abrasion resistance"

2.) Decalcified sheep pelts are picked as in Example 1. Then in the pic, 12% of a mixture of 1 part Chromium lignosulfonate and 2 parts aluminum lignosulfonate dissolved. The pelts are treated with agitation for 6 hours. The barrel stays there overnight. After draining the Broth, the pelts are rinsed «The tanned material is then with a liquor of 30% water, 6% dicyandiamide and 12% formaldehyde (29%) added, treated at 45 ° for one hour, acidified with concentrated hydrochloric acid (pH 1.5)

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and treated again for an hour. The leather is then completed in a known manner. Through appropriate Neutralization and fatliquoring, the flexibility of the leather can be controlled as desired. Tear resistance, Abrasion and temperature resistance are very good «The color is almost white and the specific weight is very low.

Claims

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Claims (2)

Claims 1. Process for, tanning of hides and skins by condensation of lignosulfonic acid and / or its salts, amino compounds and aldehydes within der.tierischen skin, thereby characterized in that initially ligninsulphonic acid and / or its salts are stored in the tanned material during pickein, then after rinsing the tannin in a new liquor, the monomeric amino compounds and aldehydes are introduced into the skins and that the condensation is then carried out in a manner known per se by adjusting the pH to below 7 ». preferably below 2, whereupon the leathers or hides normally to be completed in a way » 2. The method according to claim 1, characterized in that the * amino compounds and aldehydes containing liquor low Amounts of lignosulfonic acid in the form of its alkali or alkaline earth metal salts to be added 3 · Process according to claims 1-2, characterized in that that the lignosulfonic acid component added to the pimple is 2-preferably Contains 3 # chromium (calculated as all CrpO *). 4. Process according to Claims 1-3, characterized in that urea, dicyandiamide and / or melamine are used as the mino compounds. 809805/0563 Subjects lArt 7 fcl At> s.ii No. 1 sentence 3 da «Changes · * v. 4.9.1967 »