Method of ashing-dehairing of skins

 

(57) Abstract:

The invention swinging ashing-dehairing of skins and can be used in making leather for Shoe upper from the skins of cattle. The method consists in liming-obeznalichivanie raw material in a solution of sodium sulfide, calcium hydroxide and gidroksietilirovannogo carboxymethylamino starch. The method improves the quality of skin and reduce pollution of wastewater by organic compounds. table 1.

The invention relates to the leather industry and can be used in otlochno-ash processes in making leather for Shoe upper from the skins of cattle.

There is a method of ashing-obeznalichivanie leather raw material, capable of handling otmechennogo material in an aqueous solution of sodium sulfide, calcium hydroxide, water-soluble polymer is hydrolyzed polyacrylonitrile and polyethylene glycol (SU, 1735376 A1, class C 14 C1/06, 23.05.92).

The disadvantages of this method is the duration (48-50 hours) the process of ashing and contamination of wastewater residues of hydrolyzed polyacrylonitrile and polyethylene glycol having a low stepheneb ashing-dehairing of skins in a solution of calcium hydroxide and sodium sulfide in the presence of 0.3 to 1.2% by weight of the raw material of the water - soluble polymer cellulose ethers and organic compounds, thiol number (DE 2930342, CL C 14 C 1/00,19.02.81).

The disadvantage of this method is that it does not allow you to get ready skin with high strength properties of the surface layer. In addition, the presence of organic compounds on the basis of thioglycolate and mercaptans creates a problem with wastewater treatment.

The technical result of the invention is to improve the quality of the skin and reduction of pollution of wastewater.

This result is achieved in that in the method of ashing-dehairing leather raw material by processing it in a solution of calcium hydroxide and sodium sulfide in the presence of water-soluble polymer as a water-soluble polymer used gidroksietilirovanny karboksimetilirovaniya starch (GECMC) in an amount of 1.0 to 1.5% by weight of raw materials. GECMC is a powder light cream color soluble in water and acids. PH of 1% aqueous solution of 8-10, produced according to TU 6-55-221-1399-95. Currently used in the oil industry.

Conducting ashing-dehairing in the presence GECMC promotes uniform distribution of sodium sulfide and hydroxine GECMC allows ashing process when J. K. 0,9-1,2 and avoid rubbing the front surface of the skin and to eliminate the phenomenon of "borosilicate" in the form of wrinkles on the strap, rope, cord part of the skin and reduce the detached skin.

With the introduction of GECMC less than 1.0% by weight of the raw material does not increase the strength properties of the surface layer of the hide. Introduction more than 1.5% can lead to an increase in the viscosity of the treatment solution, which complicates its penetration into the structure of the dermis.

The method is as follows.

Raw cattle after washing and soaking loaded into the drum when J. K. 0,9-1,2 and a water temperature of 28-30oC. Then the drums enter 1.0 to 1.5% reagent GECMC and pour a solution of sodium sulfide in the amount of 2.0 to 2.5% by weight of raw materials. After 15 minutes of treatment in the drum dispense a solution of calcium hydroxide at a flow rate of 3.0-3.5% by weight of the raw material and 0.1% nonionic surfactant. After 45 minutes of continuous rotation of the drum is stopped within 12 hours adhere to the following processing mode - 15 minutes of rotation, 30 minutes of rest.

Skins after ashing-dehairing must be completely abesolutely, with sufficient elasticity, homogeneous and translucent thickness incision along the spine line.

the ke by standard methods. After draining the fluid produce liming-dehairing when J. K. 1.5 and a temperature of 20oC in an aqueous solution of sodium sulfide in the amount of 2.5% by weight of the raw material and calcium hydroxide 3.5% in the presence of GECMC in the amount of 1.0% by weight of raw materials. The processing time of 12.5 hours

Further, the processes and operations performed by standard methods.

Example 2

The skins of cattle treated as in example 1, but the liming-dehairing produced in the presence of 1.25% GECMC.

Example 3

The skins of cattle treated as in example 1, but the liming-dehairing is carried out in the presence of 1.5% GECMC.

Example 4

The skin of cattle treated as in example 1, but liming-obeznalichivanie enter 0,8% GECMC.

Example 5

The skins of cattle treated as in example 1, but liming-obeznalichivanie enter 1,7% GECMC.

Qualitative indicators of finished leather in comparison with the skin of the prototype presented in the table.

Using the proposed method allows to obtain high-quality leather for the uppers with high strength properties.

Method of ashing-onesoles vodorastvorimogo polymer, characterized in that the water-soluble polymer used gidroksietilirovanny karboksimetilirovaniya starch in the amount of 1.0 to 1.5% by weight of raw materials.

 

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