CS264766B1 - Self-alkalinizing mixture for tanning containing aluminium salts - Google Patents

Abstract

The solution is used in tanning leather and fur and can be applied in all tanneries and tannery auxiliary plants substances. Using self-compacting compositions when making aluminum salts, a better one is achieved throughout the process, egal and fast pročinění. MgO pellets are heat treated magnesium oxide with reduced reactivity. Chromium hydroxide acts both slowly neutralizing agent; contributes to tanning leather. They are being used at the same time substances forming aluminum salts complexes, thus modifying their doing Properties.

Description

BACKGROUND OF THE INVENTION The present invention relates to a self-base leather tanning composition useful in converting a wort to a leather. The mixture contains aluminum salts.

The tanning compositions containing hitherto known aluminum salts are predominantly composed of basic aluminum sulfate or chloride. In order to keep these salts in solution, substances capable of forming complexes with aluminum salts are added. These include citric acid, acetic acid, phthalic acid and many others. The preparation of basic aluminum salts is carried out in aqueous solution by the addition of alkali and the resulting solution having a low dry matter needs to be dried, which is energy intensive. It is not known to use gradually alkalinity-binding substances as additives in tanning compositions containing aluminum salts.

Some of the disadvantages of the prior art are eliminated by the process according to the invention, wherein a self-basifying tanning composition based on trivalent aluminum salts is used which comprises, as an acid-binding substance, dried chromium hydroxide in an amount of 2.0 to 25.0% by weight. the weight of the anhydrous aluminum salts and / or 2.0 to 20% by weight, calculated on the weight of the anhydrous aluminum salts of the sulphite liquor-containing pellets, containing magnesium salts of a composition of 85 to 95% by weight; % magnesium oxide and 2 to 15 wt. parts of calcium oxide. If both are used, they are added in an amount such that their total weight does not exceed 100% calculated on the weight of the aluminum salts in the mixture. Addition of acidity-binding agents gradually results in the preparation of high-basic tanning salts of aluminum without the addition of compounds entering the aluminum complex with aluminum salts. If these substances are added, it is sufficient that their content in the mixture is adjusted according to the requirements of tanning technology, and not so as to maintain highly basic aluminum salts in solution.

The MgO pellets used in the above mixture are formed by the long-term heating of the magnesium oxide in the combustion chamber of the MgO recovery boiler by burning the sulphite leaches from wood pulp production using magnesium salts. The heating temperature is 900 to 1500 ° C, and typically ranges from 14 to 28 days to heat. This results in a partial reduction in reactivity against commercially available magnesium oxide, so that MgO pellets are a more suitable raw material for the preparation of self-base mixtures.

The use of dried chromium hydroxide or sulphite leach pellets containing magnesium salts gradually neutralizes the acids contained in the aluminum tanning salts, both in the tanning process and does not, due to the reduced reactivity, present the risk of irregular tanning and thus deteriorating their quality. The process of the invention can be used in all reagent plants and tanneries.

The process according to the invention is illustrated by the following examples of use, which are only a few of the many possible variants.

He did

The tanning mixture of the stated composition with

Pellet composition:

prepared by mixing 450 kg of alum ammonium alum, 10 kg of citric acid.

kg pellets on

MgO content CaO content Fe ₂ O ₃ content SO2 content

Insoluble matter in

94.2 % wt 3.4 % wt 0.4 % wt 0.9 wt HCl 1: 1 1.1 % wt

Example 2.

/

The tanning mixture contained 666 kg of crystalline aluminum sulfate and 70 kg of MgO pellets of the same composition as in Example 1.

Example 3

We prepare the tanning mixture for combined tanning by mixing 342 kg of anhydrous aluminum sulphate,

120 kg of chromium hydroxide, 10 kg of phthalic acid and 4000 kg of water. Use as a tanning bath.

Example 4

Mix 241 kg of crystalline aluminum chloride and 120 kg of chromium hydroxide with an active ingredient content of 35.9% by weight, obtained by spray-drying the concentrated mixture after precipitation of the chromium salts in the waste water with alkali. To this mixture, add 20 kg of calcium lactate and use it as a tanner's aid in tanning leather.

Example 5

We will use descaled and spiked clearing. All other data are calculated on its weight. Into the rotary barrel we put the wort and fill 100% of the mass. water and add 4 wt. of the preparation according to example 1. The movement time is 6 hours, till morning at rest, TS 85 ° C, roll in the morning and throw the leather on the sock. 24 hours. Other operations according to leather assortment. Leather treated in this way can be sprinkled without problems.

In the original technology that does not use gradual basification, 6.7% alum ammonium must be used and gradual basification during tanning. The shrinkage temperature of the leather is 78 ° C. Made leather can not be well worn.

Claims (2)

A self-base leather tanning composition based on a trivalent aluminum salt, characterized in that it comprises as an acid-binding substance a dried chromium hydroxide in an amount of 2.0 to 25.0% by weight. and / or pellets from the combustion of sulphite liquor containing magnesium salts having a composition of 85 to 95 wt. % magnesium oxide and 2 to 15 wt. % calcium oxide, in an amount of 2 to 20 wt. calculated on the weight of the trivalent aluminum salts used, expressed as anhydrous aluminum sulphate. 2. A self-base mixture as claimed in claim 1, which contains substances capable of complexing with aluminum salts in an amount of 1 to 20% by weight, based on the weight of the trivalent aluminum salts used.