RU2233337C1 - Method of treating raw hide - Google Patents

Abstract

FIELD: chemical treatment of raw hide.

SUBSTANCE: method includes the treatment of raw hide with a composition containing polyethylene polyamine, calcium hydroxide, sodium sulfide and nonionogenic surface-active substance.

EFFECT: enhanced quality of hide and decreased concentration of amino compounds in waste.

1 tbl

Description

The invention relates to the leather industry and can be used when carrying out soaking and ash processes in the production of leathers from various types of raw materials.

There is a method of processing leather raw materials by soaking and gelling with a composition containing thiourea, surfactant and dimethylamine, in the presence of calcium hydroxide in an amount of 2.5% by weight of raw materials (Austrian patent, 381952, CL 14 C 1/06, 12/29/08 )

The disadvantage of this method is the relatively long duration of the gouging - 24 hours and the incomplete removal of the remaining hair from the skin.

The closest analogue of the proposed technological solution is a method of processing leather raw materials by soaking in an aqueous solution of a nonionic surfactant and ashing with a composition including, wt.%:

Aliphatic amine or mixture of aliphatic amines 73.5-75.0

Sodium hydroxide 20.0-22.0

Polyacrylamide with molecular

weighing 200 thousand-500 thousand 4,5-5,0

moreover, this composition is introduced directly into the surfactant solution after soaking in the amount of 5-15% by weight of the raw material, and 35% monomethylamine or 33% dimethylamine, or a 1: 1 mixture thereof, is used as an aliphatic amine or a mixture of aliphatic amines ( SU 995515 A, class C 14 C 1/04, 09/30/83].

The disadvantage of this method is the use of a significant amount of aliphatic amines (3.5-10% by weight of raw materials) that pollute wastewater with amine-containing compounds. In addition, this solution does not allow to sufficiently loosen the structure of the dermis, which leads to hard skin.

The technical result of the invention is to improve the quality of leathers and reduce the content of amino compounds in the wastewater of enterprises.

This technical result is achieved by the fact that in the method of processing leather raw materials by soaking and gritting with a composition comprising an aliphatic amine and calcium hydroxide, in the presence of a nonionic surfactant, sodium sulfide is additionally introduced into the composition, polyethylene polyamine is used as an aliphatic amine, and a surfactant is introduced directly to the composition in the following ratio of components, wt.%:

Polyethylene polyamine 8.5-10.5

Calcium hydroxide 34.0-38.0

Sodium Sulfide 34.0-38.0

Nonionic surfactant 15.5-21.5

A distinctive feature of the proposed method is that the introduction of polyethylenepolyamine into the ash solution improves the separation of the dermis structure into thinner elements, and its alkaline nature allows processing at optimal pH values of 12.6-12.8.

The use of sodium sulfide and calcium hydroxide in a ratio of 1: 1 contributes to the production of a finely dispersed system with a particle size of 2-10 μm, which easily and quickly penetrate the active centers of the collagen molecule and provide maximum loosening of the dermis structure, which allows you to get soft, elastic skin.

As a result of the combined action of alkaline reagents, including polyethylene polyamine, in the presence of surfactants, a higher degree of degreasing is achieved, especially when processing pork raw materials.

The introduction of polyethylene polyamine less than 8.5 wt.%, Calcium hydroxide and sodium sulfide less than 34.0 wt.% Each does not allow to achieve the optimal degree of separation of the structure of the dermis to obtain leathers with high performance properties.

The introduction of polyethylene polyamine more than 10.5 wt.% Calcium hydroxide and sodium sulfide more than 38.0 wt.% Each is impractical due to excessive dermis and the possibility of perfume, as well as environmental reasons.

Polyethylene polyamine (PEPA) is prepared by condensation of monomeric ethyleneamines in the presence of catalysts. PEPA is produced in accordance with TU 2413-375-00203447-99 and is a yellow liquid without mechanical impurities.

Neonols (TU 2483-077-05766801-98), Prevocel (Germany), etc. are used as nonionic surfactants.

Skins of cattle, pork or sheepskin are soaked for 4.5-6.5 hours at 1.5-2.2 and a temperature of 30-35 ° C. After draining the bath, the raw materials are garnered at a temperature of 38-40 ° C and g. 1.8-2.2 for 16-20 hours in the following composition, wt.%: Polyethylene polyamine 8.5-10.5, calcium hydroxide 34.0-38.0, sodium sulfide 34.0-38.0, nonionic Surfactants 15.5-21.5. Consumption of the composition of 6-11% by weight of raw materials. Further processes and operations are carried out according to known technologies.

The composition for the soldering of raw materials is prepared as follows.

In the container equipped with a stirrer, at the stated ratio of the components, calcium hydroxide and sodium sulfide are loaded, then polyethylene polyamine and surfactant are added with constant stirring.

Example 1. Skins of cattle after soaking are subjected to ashing at a temperature of 35 ° C and g. 2.0 for 18 hours with a composition containing, wt.%:

Polyethylene Polyamine 8.5

Calcium Hydroxide 38.0

Sodium Sulfide 38.0

Nonionic surfactant 15,5

Consumption of the composition of 8% by weight of raw materials. Further processes and operations are carried out according to the methodology for the production of leathers for upper shoes with a natural front surface.

Example 2. Pork raw materials after soaking are processed, as in example 1, but the gilding is produced by the following composition, wt.%:

Polyethylene 9.5

Calcium hydroxide 36.0

Sodium Sulfide 36.0

Nonionic surfactant 18.5

Further processes and operations are carried out according to the method of production of elastic leathers for shoe upper.

Example 3. Sheepskin after soaking is treated, as in example 1, but the gilding is produced by the following composition, wt.%:

Polyethylene polyamine 10.5

Calcium Hydroxide 34.0

Sodium Sulfide 34.0

Nonionic surfactant 21.5

Further processes and operations are carried out according to the method of production of leathers for upper shoes.

Example 4. Skins of cattle after soaking are treated as in example 1, but the gold plating is produced by the following composition, wt.%:

Polyethylene Polyamine 8.0

Calcium Hydroxide 39.0

Sodium Sulfide 39.0

Nonionic surfactant 14.0

Example 5. Pork raw materials after soaking are processed, as in example 2, but the gilding is produced by the following composition, wt.%:

Polyethylene polyamine 11.0

Calcium hydroxide 33.5

Sodium Sulfide 33.5

Nonionic surfactant 22.0

Qualitative indicators of the obtained skin in comparison with the skin of the prototype are presented in the table.

Using the proposed method allows to reduce the pollution of wastewater by amine-containing compounds and to obtain finished leather with high performance properties.

Claims (1)

A method of treating leather raw materials by soaking and gelling with a composition comprising an aliphatic amine and calcium hydroxide in the presence of a nonionic surfactant, characterized in that sodium sulfide is additionally introduced into the composition, polyethylene polyamine is used as an aliphatic amine, and surfactant the substance is introduced directly into the composition in the following ratio of components, wt.%: Polyethylenepolyamine 8.5-10.5 Calcium hydroxide 34.0-38.0 Sodium Sulfide 34.0-38.0 Nonionic surfactant 15.5-21.5