SU97565A1 - The method of preparation of leather raw materials for storage - Google Patents

Description

With existing methods of processing hides intended for making leather products, they are prepared for storage only by preserving without prior removal of hair. The dehairing of the hides is usually carried out at the leather factories, then the dehaird hides are immediately or after a short period of time (2-3 hours) subjected to subsequent transformations into the skin: clearing, dezoling, softening, pickling, tanning, etc.

These methods have a number of significant drawbacks, as follows.

1.When deaeration at leather factories, spread mixtures with a high content of sodium sulfide (40-80 g / l) or with smaller amounts of it (15-25 g / l), but with the addition of sodium sulfite, are used, which leads to a decrease in the quality of wool.

2. Since the dehair skins must be subjected to subsequent operations immediately or after a short period of time, the wool must remain on the skins until they are put into production. And this leads to the fact that wool, mainly of mixed and fine-wooled sheep, cannot be realized before this time, as a result of which there is a deceleration of working capital.

3. The hair coat on the skins, delivered to the leather factories, hides the facial defects of the skin, which often leads to an incorrect definition of the production purpose of them and the wrong method of processing, as a result of which part of the leather raw material is used inefficiently.

It has been proposed to prepare the raw hides for storage by dehairing it and subsequent preservation. However, this method did not spread as the dehairing according to this method was carried out by shvitsevanie (podparkoy) or namazyu using high concentrations of sodium sulfide, which impairs either the quality of the dermis of the skin (when steaming), or the quality of wool.

In addition, this method requires the execution of ashes, desalting, milling and pickling operations immediately after the dehairing, which is very difficult; moreover, the pickled hide is still subject to deterioration upon further storage.

The proposed method of preparing leather raw materials for storage by dehairing using a mixture of sodium sulphide, soda and lime. Subsequent canning No. is free from the above-mentioned drawbacks of the known methods and allows improving the quality of loose wool and dehaird hides, as well as using them more rationally.

This method is as follows.

The tanning raw material (skins) is first defolded by the above namaz mixture containing only 8-10 g1l of sodium sulphide, followed by washing at 22-25 ° for not more than 4 hours. and relative humidity of the room is not lower than 75%; the dehumidified raw materials are then washed with an aqueous solution of ammonium sulfate and canned with a neutralizing mixture containing about 20-25% sodium chloride, 5% ammonium sulfate and 0.4% naphthalene based on the weight of dehairing hides.

According to the authors, the wool obtained by the proposed method from merino sheepskin and sheepskins does not differ in strength, length, fineness and quality from wool removed by swiss, i.e., wool not subjected to chemical treatment, and suitable for finely combed and fine cloth Skins, dehairing and mothballed by the proposed method, retain basically their original strength after long storage and transportation.

Subject invention

A method of preparing leather raw materials for storage by dehairing with the use of sodium sulphide, soda and lime and subsequent preservation, which is characterized in that, in order to improve the quality, the skins are rubbed with a paste containing about 8-10 g / l of sodium sulphide , with a bedding of not more than 4 hours. at 22-25 ° and relative humidity of the room is not lower than 75%, after which the dehair skins are washed with an aqueous solution of ammonium sulphate and preserved with a neutralizing mixture containing about 20-25% of sodium chloride, 5% ammonium sulphate and 0.4% naphthalene by weight of dehydrated hides.