CC BY
8BASIC OXIDIZING DYES USED IN THE DYEING OF FUR SEMI-
FINISHED PRODUCTS
Toshpulatova M. B.
Trainee teacher "Department of Technology and Design of Products and Leather"1 Bukhara Institute of Engineering and Technology-Uzbekistan (e-mail: toshpulatova 910@mail, ru) Akramov Sh. student group 404-21 TLI https://doi.org/10.5281/zenodo.7481005
Dyeing and fattening processes in fur technology are the most important. The fur industry uses oxidative dyes for fur, which are special classes of organic compounds belonging by chemical structure to aromatic amines, phenolics or aminophenolics. When oxidizing agents act on these compounds, dyes are formed that are capable of giving a certain stable fur coloration with prior etching of hair with salts of heavy metals [1].
At present, the following main classes of dyes are used in the fur industry: oxidative (this includes black aniline), cubic, mordant for fur, dispersed and metal complex dyes.
Oxidative dyes are of great use: dyeing with them is carried out at low temperatures, and they give good imitations of valuable furs. [4].
Urzol black for fur D. Dyes are formed in the hair structure as a result of oxidation of dyes with hydrogen peroxide (perhydrol 30%) at temperature of 35-38 degrees in a slightly alkaline environment (pH=8-8, 5).
The most common dyes are urzene "D" black for fur, urzene brown for fiir "A", gray "DA", yellow for fur "H", pyrocatechin (catechol), resorcinol, paraaminophenol, metaaminophenol, pyrogallol, metol, hydroquinone and others. Urzol "D" black for fur is paraphenylenediamine-crystals of light gray color or in the form of black crystalline stones.
Pyrocatechin-1, 2-dioxybenzene-powder-crystal or plates of gray, brown, pink color. Easily soluble in hot water, in combination with the dye black for fur "D" colors hair black.
Para-aminophenol - brown organic dye for fur brand "A". Powder of light yellow color. Dyes fur brown, in combination with urzene black for fur "D" dyes hair in a dark brown color.
Urzol black Pyrocatichin Resorcinol
Resorcin-1, 3-dioxybenzene. Resorcinol-1, 3-dioxybenzene- colorless or slightly colored yellow-green, well soluble in hot water. Resorcinol combined with black for fur "D" dyes fur a light resistant brown color.
Metaaminophenol - brown organic dye for fur "A", a powder of dark purple color, dyes fur in light brown and beige color. Combined with Ursol HD" dyes hair to a light brown or chocolate color. Colored urzols include yellow, gray, olive and the semi-products: pyrogallol, methyl, hydroquinone.
Oxidizing dyes are produced by many foreign companies: Ursols - BASF, FRG - AKNA, Italy; NAKO - Hechst, FRG-uramines - Francolor, France; Benzofur Czech Republic; Futramines - Poland; Rhodols - USA.
Dyes are stored in plastic bags, preliminarily vented. In the open air, chemicals quickly oxidize and lose their properties. It should be stored in a dark room.
The dyeing process is influenced by the following parameters: the composition of the dyeing solution, the liquid ratio, temperature and duration of dyeing. [2].
The composition of the dyeing solution: dyes, oxidant, alkali, wetting agents (surfactants), sodium chloride. Several dyes are usually used to obtain a uniform color of fur. The black one for fur "D" is taken as a base, and the others are added as highlighting agents. Dyeing is carried out after the furs are etched with chromium salts or copper salts or iron salts.
Ursol black for fur "D" plus pyrocatechin is often used when dyeing fur black, Ursol "D" plus resorcinol is most commonly used when dyeing brown, brown color can be achieved with the dye urzol "D" plus-paraaminophenol or metaaminophenol, beige color is given by metaaminophenol, gray color can be obtained with urzol gray "A" or mixture-urzol "D" plus - pyrocatechin plus metaaminophenol.
Perhydrol (30% hydrogen peroxide) or hydrogen peroxide (usually 1 g per 1 g of dye) is used as an oxidizer. The oxidant is stored in a tightly closed glass container, in a dark room. Perhydrol loses its properties during prolonged storage.
To create a weak alkaline environment in the dyeing solution add ammonia 25%, the oxidation process is more vigorous. For better penetration of dyes into the hair column, surfactants are added to the solution. In order for the skins to be well washed by the solution, the liquid coefficient is taken as 12-15.
To obtain deep and intense dyeing, the temperature of the dyeing solution should be 35-380C. The optimum dyeing time is 2 - 3 hours.
Fur dyeing is carried out with the following parameter: liquid coefficient - 10 g/1, water temperature 35-380 C, salt concentration - 20 g/1. For better wetting of the hair, surfactant-1 g/1 is added. Dyeing takes place in a slightly alkaline environment: ammonia 25%-1 g/1 is added. Pre-dissolve the dye in hot water, urzol black for fur "D"-3-5 g/1, pyrocatechin -2 g/1 and poured into the solution.
Hides are loaded into the dyeing solution and stirred for 30 minutes, during this time the dyeing solution is evenly absorbed into the hair. Then Perhydrol 30%-6 ml/1 pre-dissolved in water (1:5) is introduced. The skins are stirred frequently for 2. 5 hours. Thanks to the oxidant the dye changes its structure and is firmly fixed in the thickness of the hair.
Literature:
1. Б. H. Мельников, Т. JI. Щеглова, Г. И. Виноградова. Применение красителей: учебное пособие для вузов — 3-е изд., испр. и доп. — М.: БИНОМ. Лаборатория знаний, 2014.
2. Р. Ф. Гайнутдинов Разработка ресурсосбергающей технологии крашения меховой овчины плазмо модифицированными красителями. Диссертация. Казань 2015 г.
3. Б. Н. Мельников, Г. И. Виноградова Применение красителей. М.: Химия, 1986 г. 240 с.
4. Л. А. Гарцева, В. В. Васильев Крашение натуральной кожи и меха. Методические указания. Иваново 2008 г.
5. Ташпулатова М. Б. Усовершенствование и оптимизация технологии крашения каркульевых шкур //Вестник науки. - 2022. - Т. 3. - №. 3 (48). - С. 119-124.
6. Tashpulatova М. В. Optimal options for dyeing astrakhan skins //Epra International Journal of Research and Development (IJRD). - 2022. - T. 7. - №. 2. -C. 75-78.
7. Ташпулатова M. Б. Влияние биологических факторов на изменчивость волосяного и кожного покрова пушных шкурок //Вестник магистратуры. - 2021. - С. 16.
