The processing method sheepskin

 

(57) Abstract:

Usage: for hides, sheep upon receipt fur semi-finished product. Sheepskin is subjected to: soaking off, mendrinou, degreasing, pickling. Pickling is carried out in the course of 5,5 - 6,6 h complex reagent. The last is a mixture of dicarboxylic acids (adipic, glutaric and succinic, with the total concentration in solution of 1.8 - 2.2 g/L. Then carry out the tanning dry chrome tanning agent with a concentration of 0.65 - 0.75 g/l in terms of oxide of chromium, greasing and drying. The method allows to reduce the consumption of chromium compounds tanning more than 2 times and reduce their concentration in the waste liquid 7.5 times when high quality fur semi-finished product and intensifies the process. table 2.

The invention relates to the fur industry and can be used for tanning skins of sheep upon receipt fur semi-finished product.

There are various ways of handling sheepskin, in which the pickling skins of sheep carried out using mixtures of sulfuric, acetic and formic acids, and tanning conduct dry chrome tanning agent with a concentration of 1.5-5.0 g/l (Simonov, E. A. and other Processing of fur and fur. M: Light and food is the first industry, 1983).

These methods are characterized by a large consumption of acid and chrome tanning agent, insufficient absorption sheepskin and consequently a high content of chromium compounds (III) in the waste liquid, the significant duration of the pickling and complexity of the process of tanning, which consists in the use of additional chemical compounds. However, fur semi-finished product, getting on these technologies is the lack of ductility leather in General and especially her face layer.

The closest analogue to the technical essence is a method of treating skins of sheep (unified technology for processing fur sheepskin. M: Createrepo, p. 3.1.33, 1978).

The known method includes: soaking off, meskene, degreasing rinsing and pickling when the content of sodium chloride 40 g/l and sulfuric acid 1.5 g/l for 6-8 hours, followed by tanning dry chrome tanning agent with the basicity of 35-40% and a concentration of 1.5 g/l calculated as the content of chromium oxide.

The disadvantage of this method is the low degree testing of chrome tanning agent at significant expense. Thus, the initial concentration of chromium compounds is 1.5 g/l, and plre, thereby increasing the toxicity of wastewater fur factory, which has a negative impact on the environment.

The technical result is achieved in that in the method of processing of sheepskin, comprising: soaking off, meskene, degreasing, rinsing, pickling, tanning, greasing and drying, according to the invention, the pickling is carried out in a period of 5.5 to 6.5 h complex with a reagent consisting of a mixture of dicarboxylic acids in the ratio, wt.%: adipic 42,7, glutaric 38,5, amber 18,8 with the total concentration in solution of 1.8-2.2 g/l and tanning dry chrome tanning agent with a concentration of 0.65-0.75 g/l in terms of oxide of chromium.

This embodiment of the method allows to reduce the consumption of chromium compounds tanning more than 2 times and reduce their concentration in the waste liquid 7.5 times while ensuring high quality fur semi-finished product. The use of integrated reagent consisting of a mixture of dicarboxylic acids with a total concentration of 1.8 - 2.2 g/l allows you to simultaneously achieve the purpose of pickling and provide the optimum degree of testing compounds chromium tanning. The inventive method allows to intensify the process. So, the duration of the pickling of setbytes of 0.65 - 0.75 g/l, in terms of oxide of chromium, allows on one hand to get fur semi-finished product with performance properties that meet the requirements of GOST 4661-76, and on the other, significantly reduce their content in the spent solution.

The method is as follows. Sheepskin dry-salted, macromolecule or acid-salt food preservation techniques are: soaking off, hold meskene, degreasing with intermediate mettenheim, wash. Further the sheepskin are treated for 5.5 - 6.5 h in a solution containing sodium chloride with a concentration of 40 g/l and a complex reagent with a concentration of 1.8 - 2.2 g/l, consisting of a mixture of dicarboxylic acids in the ratio, wt.%: adipic 42,7, glutaric 38,5, amber 18,8, which is a waste of one of the enterprises of chemical industry of THE-6-03-20-70-82, when LC=7, initial temperature 40oC. Tanning conduct dry chrome tanning agent with the basicity of 35-40% and the concentration of 0.65 - 0.75 g/l in terms of chromium oxide when LC = 7 and in the presence of sodium chloride with a concentration of 40 g/l After 4 h tanned test the temperature of the welding, which should not be below 70oC. If necessary, add sodium carbonate to a concentration in the solution is 0.5 g/l and PM is 6 o'clock

Examples of specific implementation method are presented in table. 1, and the properties of the fur semi-finished product according to examples 1-8, prototype and indicators GOST in the table. 2.

As can be seen from the table. 1 and 2, the machining conditions in the present method provide along with saving chemical materials and intensification of the process of obtaining high quality fur semi-finished product. All indicators of the properties meet the requirements of GOST, and some of them exceed obtained by the prototype. So, the leather sheepskin obtained by the present method has better plastic properties. This is evidenced by a higher value of residual elongation and an increase of 14% elongation at the crack front layer of sheepskin. A very important characteristic of sustainability fur semi-finished product to ageing is the pH of aqueous extract of the leather. Conditions allow you to increase this figure to 20%, and that is particularly valuable, with a simultaneous increase in the plasticity of the leather.

The conditions for executing the method are optimal. This is confirmed by the fact that changes in the concentration of the complex reagent and processing time in a big way causes a decrease in the temperature of the welding Koshevoy TCI, after tanning fluid. At the same time decreases the pH of water extract from the leather, which negatively affects the safety of articles of fur semi-finished product in time. The decrease in the concentration and processing time of complex reagent results in dipropylamino leather, which leads to deterioration of the elastic-plastic properties of fur semi-finished product.

The decrease in the concentration of chrome tanning agent is not possible to obtain the desired temperature welding of the leather, and the increased consumption of tanning agent is impractical due to the increase of its concentration in the spent solution and increases in the cost of processing of sheepskin.

A significant advantage of the method is simple, its execution and a significant decrease in the concentration of chromium compounds (III) in the wastewater. Thus, in the prototype, the concentration of chromium oxide in the total wastewater production sheepskin constitute 66.6 mg/l, while total consumption of water per skin 2398 l, and by the present method is to 8.9 mg/L.

This allows no additional cost for the treatment of wastewater from compounds of chromium (III) can be discharged into municipal sewers as limit their concentration is 10 mg/L.

The way the Cabinet, characterized in that the pickling is carried out in the course of 5,5 - 6,6 h complex with a reagent consisting of a mixture of dicarboxylic acids in the ratio, wt.%: adipic 42,7, glutaric 38,5, amber 18,8, with the total concentration in solution of 1.8 - 2.2 g/l and tanning dry chrome tanning agent with a concentration of 0.65 - 0.75 g/l in terms of oxide of chromium.

 

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FIELD: fur industry, in particular, method for evaluating pickling quality of leather web in tanning of fur and sheepskin raw material.

SUBSTANCE: method involves providing testing on parallel groups of fur sheepskin after pickling on three topographic portions of sheep skin surface: skirt, spine and neck portions; processing samples of each group with acid-salt solution for 24 hours; withdrawing sheepskins of each group from acid-salt solution in predetermined time intervals; removing excessive liquid; placing said samples into tensile testing machine and stretching lengthwise of spine line by 40% relative to initial length thereof; holding samples in stretched state for 1 min and withdrawing from tensile-testing machine; leaving samples in free state for 10 min; determining residual elongation value in mm.

EFFECT: reduced time for determining quantitative pickling characteristic of skin web.

2 tbl, 2 ex

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