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7Iyntmsis^^
J. Sh. Azimov
PhD. Bukhara Engineering-Technological Institute Bukhara, Uzbekistan Z. O. Mukhammadova Ml 1-22 TELF Bukhara Engineering-Technological Institute
Bukhara, Uzbekistan https://doi.org/10.5281/zenodo.7480992
The fur industry plays an important role in the production of high quality goods using advanced technologies developed on the basis of the achievements of domestic and foreign science and technology, allowing to reduce material and labor costs. The main task facing the fur industry is to better meet the needs of the population in fur clothing, hats and other products of high quality. To implement these tasks the fur industry has technically equipped with rational production, dyeing and finishing technologies, modern equipment and qualified workers.
The fur and leather industry is facing big, responsible tasks, the main ones being:
- new chemical materials and further chemicalization of production:
- full and rational use of all resources of fur and leather raw materials:
- maximum use of the skins of astrakhan for the production of high quality products;
- further specialization of tanneries and fur factories;
- improving the quality of products and expanding their range;
- improving the use of valuable waste of tannery and fur production
To improve the quality of different types of leathers, dubbing and filling with synthetic polymers is applied. Leathers produced with the use of synthetic polymers are characterized by increased wear resistance, low water permeability, fairly uniform properties in topographic areas, increased resistance to the action of chemical reagents and microorganisms.
When synthetic polymers are introduced into the skin in the process of tanning, their action with collagen on the accessible inner surface of the dermis occurs not only indirectly (polymer-collagen), but also through protein-fixed tanner particles (polymer-tanner-collagen). In the latter case, depending on the nature of the polymers and tanning agents used, bonds of different strengths are formed, up to chemical ones. In this case, the same polymer molecules can react with the tanning agent particles, which are connected to the protein molecular chain systems (collagen-tanning agent-polymer-tanning agent-collagen). Thus, there is an additional binding
of the dermis structure. As a result, the skin's resistance to heating in a moist state is increased, its fibrous structure is strengthened, and the formation of the dermis volume is improved.
Urea and meleminoformaldehyde resins are widely used in tanning and fur industry. When tanning with the mentioned amino resins, formaldehyde is always present in the system. It is found in the solution of the methylene compounds and is also released during their condensations. The resins are not only good tanning agents, but also have tanning properties. Methyl urea and molomene compounds and their condensation products containing free methylene groups can react with collagen like formamide and take part in cross-linking of protein molecular chains. Covalent bonding between methylene groups and amino groups of protein is proved by infrared spectroscopic studies of gelatin films treated with trimethylene melamine. According to the results of these studies, hydrogen bonds can be formed simultaneously. They occur between the amino- and carbonyl groups of the protein and, respectively, the hydroxyl and imino groups of trimethylolmelamine.
In a similar scheme, hydrogen bonding is formed in the case of methyl urea compounds. Leather tanned has a white color, well filled (especially in the peripheral areas), resistant to the action of elevated temperatures, light, acids, shelves and sweat. They are well sanded and easily stained.
Resin doping of semi-finished chrome tanning materials results in leather with more uniform properties in the topographic areas, with a denser face layer.
Treatment with resins can also precede chrome tanning. Good results are obtained, for example, when treating shin instead of piquelizing with dimethylol-urea followed by its condensation under the influence of acid contained in the solutions of tanning compounds in the structure of the dermis is formed chrome-urea-formaldehyde resin. Such way of tanning allows to get heat-resistant, dense and well filled leather with less consumption of chrome compounds.
Treatment of shin with aqueous emulsions of epaxide resins usually produces leather with a welding temperature of 80-850 C. Even after repeated nodding in water, it remains strong, soft and porous after drying: the welding temperature is practically unchanged. Studies have shown that the formation of such bonds is due to the reaction of resins with amino groups, hydroxyl and carboxyl groups of collagen.
Epoxy resins can be used for tanning with other tanning agents. When tanning with epoxy resins the leather is obtained with increased strength, thermal resistance, fullness and density; hygienic properties of leather are not deteriorated.
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2. В. И. Белякова, В. Г. Зайцева, JI. Н. Курлетова. "Технология меха и шубной овчины" 1984 г.
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