DE1494825C3 - Process for the immediate tanning of limed bare - Google Patents

Description

Tanning with chromium (III) salts is common carried out so that the limed pelts are first decalcified and peeled and that then the actual tanning process follows, in the course of which the tanning liquor is blunted, d. H. your alkali in carefully added dosed amounts. This process is tedious and cumbersome. One already has recommended to use so-called self-blunting tannins, for example basic chromium formates, in order to avoid the separate dulling of the tanning liquor and the tanning process to accelerate. Such tanning agents have in fact proven very effective, including their use but requires liming and pimple pimples.

In the German patent specification 643 088 and the British patent specification 550 647 the tanning of described decalcified pelts with chromium salts without prior pimple. From the German patent specification 627 110 is also known, alkali salts of non-tanning aromatic sulfonic acids for decalcifying the To use pelts and to facilitate the absorption of tannin. This procedure is at the beginning tanning only contain so small amounts of sulfonic acids and their salts in the pelt that they are on the tanning itself can have practically no influence.

US Pat. No. 3,254,938 also describes the tanning of pelts in a lime-free Limers have been depilated without prior pickling.

In the course of the trend towards rationalization, the leather producing industry still has the desire for simpler and even less time-consuming tanning process.

It has now been found that it is possible to produce ashes pelts in an extremely simple and Tanning or pre-tanning directly with chromium salts in a time-saving way if the ■ limed Pelt without prior deliming and pimple with aqueous solutions or powder mixtures treated, the tannable salts of trivalent chromium and 0.5 to 10%, based on pelt weight, of sulfonic, carboxylic and / or sulfonic acids of the benzene series and / or sulfonic acids of the Naphthalene series, which can contain hydroxyl, amino, nitro groups and / or halogen atoms in the core, and / or aliphatic hydroxymonocarboxylic acids with up to 6 carbon atoms and / or aliphatic Di- and / or tricarboxylic acids with 3 to 6 carbon atoms which contain hydroxyl groups can, and / or contain ammonium or alkali salts of these acids.

This success was surprising because according to the information in F. Stather, Gerbereichemie and -Technologie, Berlin, 1948, p. 167, 1st paragraph, and in H. Herfeld, Basics of Leather Production, Dresden / Leipzig, 1950, p. 124, 2nd paragraph, lines 11 to 16, a scarred, hard and poorly tanned one Leather would have been expected. The same applies to the transfer of the US patent specification 3 254 938 method described on calcareous pelts.

Examples of possible tannable salts of trivalent chromium are chromium (III) chloride, chromium (III) sulfate, chromium alum, chromium (III) formate and basic chlorides, sulfates and formates of trivalent chromium. These chromium salts can be used in the process according to the invention in the same amounts that are also customary in known chromium tanning processes. One advantage of the process, however, is that the same results are achieved with only 70 to 80% of the amount of chromium required in known tanning processes. For full tanning, for example, amounts which _{correspond to 1.5 to 3.0% Cr 2} O ₃ , based on the pelt weight, have proven useful. Used for pre-tanning

ίο on the other hand, for example, 0.2 to 1.2% Cr ₂ O ₃ corresponding amounts of chromium salts.

Sometimes it is advantageous to use tannable salts of the together with the salts of trivalent chromium To use aluminum and / or zirconium. Examples of such salts are aluminum sulfate, Zirconium sulfate, aluminum chloride and their basic settings.

The aluminum and zirconium salts are generally used in smaller quantities than those of chromium. For example, amounts which correspond to 0.2 to 0.8% Al ₂ O ₃ or ZrO _{3 have proven useful.}

Examples of acids of the type mentioned above are resorcylic acid, nitrosalicylic acids, the dinitrobenzoic acids, the resorcinol sulfonic acids and nitrophenol sulfonic acids, the sulfosalicylic acids and sulfophthalic acids, phthalic acid, the catechol sulfonic acids and sulfobenzoic acids, the Chlorophenolsulfonic acids, chloronitrobenzenesulfonic acids, chloronitrophenolsulfonic acids, dichlorobenzoic acids and dinitrochlorobenzenesulfonic acids, the monoaminobenzenesulfonic acids, monoaminobenzenesulfonic acids and chloraminobenzenesulphonic acids, also the naphthalenesulphonic acids, naphthalenedisulphonic acids, Naphthol sulfonic acids, naphthol disulfonic acids, naphthol trisulfonic acids, dinitronaphtholsulfonic acids, Dihydroxynaphthalenesulfonic acids and chloronaphtholsulfonic acids, lactic acid, malonic acid, Maleic acid, succinic acid, tartaric acid, citric acid and adipic acid.

The acids of the type mentioned or their ammonium or alkali salts are used as individual substances or as mixtures of different individuals in amounts of 0.5 to 10%, preferably 0.5 to 5%, based on the weight of the pelts and calculated on the free acids.

The method according to the invention is distinguished by its extraordinary simplicity. It exists only in the fact that the limed skin material with the tannable salts and the acids defined above or their salts are treated in the form of their aqueous solution or their powdery mixture. If pulverulent mixtures are used, these transform the swollen nakedness into what is needed to dissolve it required amount of water free.

It is particularly advisable to carry out the treatment in the barrel and to support it with fulling. With this method, a full tanning takes about 4 to 6 hours, a pre-tanning in about Completed 2 to 4 hours. But it is also possible to carry out the tanning or pre-tanning in the pit.

The leathers obtained can then be processed in the customary manner by fatliquoring, drying, shaving and staking finished or, if a pretanning

has led to be retanned mineral or vegetable.

In practice, the method according to the invention is particularly simple if

a finished tanning agent is used, the tannable salts of trivalent chromium and optionally of aluminum and / or zircon and at least 3%, based on the weight of the tannable Salts of one or more of the abovementioned acids or their ammonium or alkali metal salts contains. For full tanning, it is preferable to use tanning agents, the 5 to 30% for pretanning preferably those which contain 30 to 70% of the acids mentioned, based on the weight of the tannable Salts.

Together with the components mentioned, inorganic or organic salts, such as the sulfates, Use chlorides, formates and acetates of ammonium, sodium and potassium.

The method according to the invention can be carried out and made possible without special controls hence a considerable rationalization of leather production. It delivers leather that stands out through high Characterized by grain firmness, fine pores and a full, supple handle.

Pre-tanned according to the present invention have the further advantage that they result in products which can be split before retanning. This gives you the option of opening the column to be inherited separately in different ways according to their character; for example you can the grain gap with chrome tanning agents, the flesh gap on the other hand with vegetable tanning agents.

The percentages given in the examples are percentages by weight and relate to the pelt weight.

example 1

Limed skin material from the liming is briefly rinsed and then with a mixture of

15% chrome alum and
1 to 2% / S-naphthalenesulfonic acid

drummed in a drum for 4 to 6 hours in a liquor of 50 to 70% water. Then as usual greased, dried, machined and shaped. A fine-pored leather of high grain strength is obtained full grip. Similar results are obtained with the following mixtures:

a) 15% chrome alum

0.5 to 1% / S-naphthalenesulfonic acid
0.5 to 1% adipic acid

b) 15% chrome alum
0.5 to 2% sulfophthalic acid

c) 15% chrome alum

1 to 2% adipic acid or phthalic acid

d) 12% of a 33% basic chromium sulfate (= 3% Cr ₂ O ₃ )
2.5 to 5% adipic acid

e) 12% of a 33% basic chromium sulfate
2.5 to 5% phthalic acid

f) 12% of a 33% basic chromium sulfate
2.5 to 5% y? -Naphthalenesulfonic acid

g) 12% of a 33% basic chromium

sulfates

1 to 2.5% sulfophthalic acid
1 to 2.5% adipic acid

h) 14% chrome alum

1 to 2% aluminum sulfate
1 to 2% adipic acid

i) 14% chrome alum

1 to 2% zirconium sulfate

1 to 2% sulfophthalic acid

Example 2

Limed skin material from the liming is rinsed and mixed with a mixture

1.5% of a 33% basic chromium sulfate

(0.4 o / o Cr, O ₃ ),
1.5% sulfophthalic acid,
1.5% adipic acid

drummed for 2 to 3 hours in a liquor of 50 to 70% water. The leather pre-tanned in this way becomes split and the two columns retanned as follows:

The grain gap is drummed with 10% of a 33% basic chromium sulfate in 50% water for 4 hours and then blunted, dried, chipped and shaped as usual.
The meat gap is drummed with 10% quebracho, sulfited, powder (calculated as pure tanning agent) in 50% water for 1 hour. Then 10% Mimosa, powder (calculated as pure tanning agent) is added. The material is drummed on until it is fully tanned.

A grain leather with a fine tight fitting is obtained Grains and a vegetable-tanned leather that gives the impression of tanned leather.

Leathers that are just as good are obtained if, for the pretanning, with otherwise the same working method, the lower I and Π specified mixtures are used:

I. 1% of a 33% basic chromium sulfate
0.5% aluminum sulfate
1.5% adipic acid
1.5% / 7-naphthalenesulfonic acid

II. 1% of a 33% basic chromium sulfate
0.5% zirconium sulfate
1.5% phthalic acid
1.5% /? - naphthalenesulfonic acid

Claims (2)

Patent claims: 1. Process for direct tanning or pretanning with chromium salts of ashes Pelts without previous pimples, characterized by the fact that limed pelts are used treated with aqueous solutions or powder mixtures without prior decalcification, the tannable salts of trivalent chromium and 0.5 to 10%, based on pelt weight, of suI fön-, carboxylic and / or sulfocarboxylic acids of Benzene series and / or sulfonic acids of the naphthalene series, the core of which is hydroxyl, amino and nitro groups and / or may contain halogen atoms, and / or aliphatic hydroxymonocarbon acids with up to 6 carbon atoms and / or aliphatic di- and / or tricarboxylic acids with 3 up to 6 carbon atoms, which may contain hydroxyl groups, and / or ammonium or Contain alkali salts of these acids. 2. The method according to claim 1, characterized in that together with the salts of trivalent chromium, tannable salts of aluminum and / or zirconium are used.