RU2796498C1 - Method for obtaining vegetable tanning material - Google Patents

Abstract

FIELD: chemical; technological industry.

SUBSTANCE: invention relates to a method for producing tanning agents for the leather and footwear industry. The method for producing vegetable tanning agent includes extracting vegetable tannin-containing raw materials with hot water, while cotton stalks are used as vegetable tannin-containing raw materials, and extraction is carried out in the presence of ethylenediamine in an amount of 3.0-5.0% by weight of the raw material, after which filtration, settling, concentration and drying of the extract are carried out.

EFFECT: expansion of the range of vegetable raw materials for the production of tanning agents used in the leather and footwear industry, the disposal of cotton processing waste, the production of a tannin extract with a high content of tannins, and an increase in the good quality of vegetable tanning agent.

1 cl, 4 tbl, 3 ex

Description

The invention relates to the chemical-technological industry, in particular, tanning and extract, and can be used in the production of vegetable tanning agents.

Various types of vegetable tannin-bearing raw materials are known, from which vegetable tanning agents are obtained for the production of leather products. These plant materials include oak, spruce, larch, pomegranate, willow, ram, sorrel, etc. [Temirova M.I., Qodirov T.J. Charm va mo'yna texnologiyasi. Toshkent.: "Turon-Iqbol" nashriyoti, 2005. - B. 163-164.].

The disadvantages of these types of raw materials is the lack of raw materials, and the high cost of the resulting finished tanning agent.

In known methods for obtaining tannin extracts from tannin-containing raw materials, processing is carried out using a surfactant-sulphonol [SU 169171, IPC C14C, publ. 03/11/1965], or polyethylene glycol sulfoether of isooctylphenol or isodecyl alcohol [SU 931746, IPC C14C 3/10, publ. 06/05/1982], which makes it difficult to concentrate the extract during evaporation and the formation of excessive foam.

The use of gasoline or alcohol in the extraction process [RU 2004592, IPC C14C 3/00, 3/10, publ. 11/15/1993], has its drawbacks: gasoline forms an azeotropic mixture, and alcohol, first of all, evaporates during the extraction process, which leads to a non-equilibrium of the "solid-liquid" phase system.

Application in the process of obtaining tanning extract [RU 2124562, IPC C14C 3/10, 3/12, publ. 01/10/1999] ammonium chloride, sodium sulfite [RU 95109038, IPC C14C 3/00, publ. February 10, 1997], trisodium phosphate [SU 81878, class. 28a, 13, publ. 07/02/1949], sodium sulfite and bisulfite [SU 162911, IPC C14C, publ. 05/27/1964], caustic soda [SU 717135, IPC C14C 3/00, publ. February 25, 1980], an aqueous solution of ammonia [SU 1102604, IPC A61K 35/78, publ. 07/15/1984], hydrogen peroxide [SU 1221251, IPC C14C 3/10, publ. 03/30/1986], aluminum sulfate [SU 1638167, IPC C14C 3/00, publ. 30.03.1991], chromium sulfate [SU 511318, IPC C14C 3/08, publ. 06/14/1976], leads to corrosion of diffusers, hardware, metal equipment and other engineering and technological communications. Moreover, the formation of water-insoluble "tannate-metal" complexes with metal ions of the used salts with oligomeric tannins is not excluded.

The prototype of the proposed technical solution is - SU 735636, IPC C14C 3/00, 3/10, publ. 05/25/1980], Vegetable raw materials for the production of tanning agents, which use amorphous seeds.

To do this, the amorphous seed husks are subjected to extraction in a special diffuser at a temperature of 70°C at the head diffuser and 95°C at the tail diffuser, followed by evaporation of the diffusion juice to a liquid extract.

The disadvantages of the technical solution is the low content of tannins and low quality. According to [Chevrenidi S.Kh. Tanning plants of Uzbekistan. Monograph. Ed. "Uzbekistan" Tashkent. 1982. - S. 66] in the amphora contains 5.71% of tannins with a good quality of 68.88%.

The disadvantage of the known amorphous-based tanning agent used is that the production and spare capacity is insufficient, the content of tannins and the quality is low.

In addition, extraction is carried out in the absence of electrolytes, or without activating reagents, at a high temperature, where oligomeric tannins undergo decomposition, as a result of which the molecular weight of the tanning agent decreases and this leads to a decrease in the content of tannins.

To expand the raw material base for the production of vegetable tanning agents for the leather industry, it is proposed to use guza-poya (cotton stalks) as a vegetable tannin-bearing raw material. The tannin-bearing part of the cotton plant is the stems of the cotton plant.

It is known [Chevrenidi S.Kh. Tanning plants of Uzbekistan. Monograph. Ed. "Uzbekistan" Tashkent. 1982. - S. 83-84], that in various parts: bark, roots, valves, leaves, flowers, cotton seeds, tannins contain up to 12%.

However, numerous published works, including foreign ones, are devoted to the study of tannic extracts of the cotton stem for medical and cosmetic purposes as pharmaceutical, medicinal, cosmetic, prophylactic preparations and agents.

A tanning extract obtained from tannin-bearing vegetable raw materials - from cotton stalks for tanning a leather semi-finished product, which has an industrial applicability is offered for the first time.

The technical result of this invention is the expansion of the raw material base of vegetable tannin-bearing raw materials, the disposal of agricultural waste, the production of a tanning extract with a high content of tannins, and an increase in the quality of the vegetable tanning agent.

This result is achieved by using cotton stalks as a tannin-bearing vegetable raw material during its extraction with warm water, and the extraction is carried out in the presence of ethylenediamine in an amount of 3-5% by weight of the raw material. After that, sedimentation, concentration and drying of the extract are carried out.

The use of cotton stalk as a vegetable tannin-bearing raw material makes it possible to expand the range of vegetable tannins, and extraction in the presence of ethylenediamine, which has a weakly alkaline amphoteric character, makes it possible to significantly increase the quality and content of tannins in the resulting tanning agent. The following processes of filtration, evaporation-concentration and drying make it possible to obtain a powdered tanning agent with a low content of insoluble, non-tannins, which is convenient for transportation, storage and use.

Cotton stalks are a technological waste of the agro-industrial complex. Uzbekistan is an agro-industrial country, where cotton stalks (guza-pai) occupy a dominant position among agricultural waste with an annual volume of more than 16 million tons. Given the fact that part of the guza-pay and other agricultural waste is used by the local population as fuel, and the other part does not find its effective use, the issue of the effective use of this waste remains not fully resolved.

One of the main problems facing industrialized countries is biomass and solid waste from agricultural activities. The accumulation and disposal of these wastes causes many health problems and damages the ecology of the environment, for example, black clouds result from the burning of waste biomass in the field.

Guza-pay can be attributed to the categories of organic materials with a fibrous structure.

The stems of cotton, bred as an annual plant, after the end of growth and cotton harvest, become stiff and covered with bark, on the surface of which there is a cuticular layer.

Cotton stalks are similar in chemical composition and structural structure to wood. This means that to determine the main characteristics of the guza-pai loose structure, one can use the general data characterizing the cellulose-containing organic systems of plant materials, the most studied of which is wood. Thus, it becomes possible to use the basic properties of wood and wood chips for crushed guza-shares. However, guza-shares have their own characteristics both in structure and chemical composition, which determine the main characteristics of the conditions for the formation of guza-shares structure formation.

As a comparison, we present some values of the chemical and mineralogical composition of selected wood species and cotton stalks [Dzhumaev D.S. Energy-saving materials based on plant-astringent composition from local raw materials of Tajikistan. Diss. on sois. uch. Art. cand. tech. Sciences. 05.23.05 - "Building materials and products". Bishkek. 2016 - S. 37].

The use of cotton stalks provides an expansion of the range of tannins with a high content of tannins in the plant extract, a high content of leathers, while reducing insoluble minerals.

The objective of the invention is to develop a method for obtaining a vegetable tannin with a high content of tannin using a cotton stalk, with a low content of insoluble minerals, which makes it possible to give the skin a high hydrothermal degradation, fullness and penetrating ability into the structure of the skin dermis, contributing to the improvement of the physical and mechanical properties of finished leathers.

The problem is solved by the fact that in the method of obtaining a vegetable tanning agent by extraction from a vegetable tannin-containing raw material with hot water, cotton stalks are used as a vegetable tannin-containing raw material, and the extraction is carried out in the presence of ethylenediamine in an amount of 3.0-5.0% by weight of the raw material, after which additionally produce filtration, settling, concentration and drying of the extract.

The use of cotton stalks as a vegetable tannin-containing raw material makes it possible to expand the range of vegetable tanning agents, and extraction in the presence of ethylenediamine makes it possible to significantly increase the quality and content of tannins in the resulting tanning agent. Further processes - settling, filtering, concentrating, adjusting pH and drying - make it possible to obtain a powdered tanning agent with a low content of insoluble minerals, which is convenient in storage and operation.

The most optimal consumption of ethylenediamine from the mass of the cotton stalk is 3.0-5.0%. The consumption of ethylenediamine when extracting less than 3.0% by weight of vegetable raw materials does not allow to obtain a tanning agent with high quality and tannin content. The consumption of ethylenediamine more than 5.0% by weight of vegetable raw materials leads to an increase in insoluble in the tanning agent and, consequently, to a decrease in its quality.

Tanning agent - from vegetable raw materials, namely from cotton stalks, is obtained as follows.

The results of semi-industrial studies with positive data are presented.

Cotton stalks from farms come for processing in the form of bundles and bales of various sizes 30-120 cm and weigh between 2-12 kg.

Cotton stalks with a moisture content of 8.0-9.0% are subjected to grinding in a DM-1 hammer mill with a mesh size of 0.25-10 mm with a dispersion of 0.8-1.2 mm, a density of 125-130 kg/m ³ , content, (%): cotton - 3, tow - 6, stem - 63-65, bolls - 3-5, leaves - 6-8, roots - 4-6, bark and bast - 10-12 of the total mass.

Sawdust of cotton stalks is extracted at a temperature of 60-70°C in the presence of ethylenediamine in the amount of 3.0-5.0% of the total mass of the loaded plant material with a hydromodulus of 3.5-4.5 for 3.0-4.0 hours at pH=8.0-9.0. Filtration of the extract from mechanical and suspended particles is carried out on mechanical filters. Then settling takes place. After settling, the extract is concentrated under vacuum by evaporation. Next, the concentrate is dried in a vacuum spray dryer to a powder state to a moisture content of 13% at 70°C.

Examples confirming the production of a tanning agent from vegetable raw materials, from cotton stalks.

Example 1. Plant materials, namely, cotton stalks are subjected to extraction, which is carried out at a temperature of 60°C for 3.0 hours at pH=8.0, in the presence of ethylenediamine in the amount of 3.0% of the total mass of the loaded plant material with hydraulic module 3.5. Filtration of the extract from mechanical and suspended particles is carried out on mechanical filters. Then settling takes place. After settling, the extract is concentrated under vacuum by evaporation. Next, the concentrate is dried in a vacuum spray dryer to a powder state to a moisture content of 13% at 70°C.

Example 2. Cotton stalk sawdust is subjected to extraction at a temperature of 65°C in the presence of ethylenediamine in the amount of 4.0% of the total weight of the loaded plant material with a hydromodulus of 4.0 for 3.5 hours at pH=8.5. The rest follow example 1.

Example 3. Cotton stalk sawdust is subjected to extraction at a temperature of 70°C in the presence of ethylenediamine in the amount of 5.0% of the total weight of the loaded plant material with a hydromodulus of 4.5 for 4.0 hours at pH=9.0. The rest follow example 1.

In table. 1. The results of analyzes of the extract of vegetable tanning agent from the cotton stalk are compared with the analogue of the amorphous seed husk.

From Table. 2 shows that the 2nd proposed option has the best performance.

Comparison of the chemical parameters of tannins of cotton stems is greater than with the extract of a vegetable tannin-containing shrub of the legume families, in particular from the husk of amorphous seeds.

When exposed to tannin extract obtained from cotton stalks (guza-pai) with lead acetate in an acetic acid medium, tannins do not precipitate and remain in solution.

When exposed to tannin extract obtained from cotton stalks (guza-pai) with bromine water, tannins are precipitated. Also, the precipitation of tannins occurs when the tannic extract obtained from cotton stalks (guza-pai) is exposed to a formaldehyde solution in the presence of concentrated hydrochloric acid when heated.

When tanning extract is exposed to Fe ³⁺ salts, it acquires a dark green color. When exposed to vanillin in an acidic environment, tannins from vegetable raw materials acquire a red color. According to the developed color reactions, it is possible to determine the correspondence of the cotton stem extract to condensed tannins.

Thus, it can be concluded that the tannins of cotton stems are non-hydrolysable condensable derivatives of catechin tannins.

The content of substances extractable by an aqueous solution of ethylenediamine is higher in cotton stalks than in some woody plant species. With this extraction, starch, pectins, inorganic salts, some polysaccharides, cyclic alcohols, dyes, hemicelluloses, uronic acids, as well as most of the tannins and low molecular weight fractions of cellulose pass into the solution.

The difference between the extractive components of cotton stalks and wood is primarily quantitative. So, in the stems of cotton, there are significantly more extractable substances than in amorphous husks.

The obtained tanning agent based on the cotton stalk can be used as a tanning agent in tanning, retanning and filling various types of leathers and for dressing fur.

Chrome-sintan-vegetable tanning was carried out according to the standard method in the presence of cotton stem extract and amorph in combination with other known tanning agents. The composition of synthetic and vegetable tanning agents are presented in table. 3.

In table. 4 shows the chemical and physical-mechanical parameters of the leather for the bottom of shoes and yuft tanned with tannins obtained from the cotton stalk, in comparison with the analogue of the combined compositions of synthetic and vegetable tanning agents.

From Table. 4 it can be seen that the 2nd proposed options (leather for the bottom of shoes and Russian leather) have the best performance.

The main advantage of the invention is the expansion of the raw material base for the production of vegetable tanning agents.

The difference of the proposed tanning agent from vegetable raw materials based on cotton stalk is that the tanning agent has a high content of tannins and has improved quality.

EFFECT: invention makes it possible to increase the quality of the tanning agent and provides an increase in the hydrothermal stability (treated with this tanning agent) of a semi-finished leather product (with increased resistance) resistant to various influences.

The use of the proposed tanning agent allows you to expand the range of vegetable tanning agents and obtain a high-quality tanning agent from a cotton stalk.

Comparative analysis with analogue allows us to conclude that the resulting tanning agent obtained from cotton stalks relative to the analogue according to the proposed option is characterized by a high content of tannins and high quality

The proposed plant material - cotton stalks for the production of tanning agent in comparison with the prototype (SU 735636, IPC C14C 3/00, 3/10) allows you to get the following advantages:

- increase in the range of industrially produced tannins;

- increase in the content of tannins in tannins from 7.02% to 14.03%;

- increase in the quality of the tanning agent from 52.3% to 64.1%;

- reduction in the amount of water-insoluble minerals from 2.38% to 2.14%;

- improving the quality of finished leather by increasing the quality of the tanning agent obtained from the cotton stalk, in particular, increasing the thickness, tensile strength, etc.

Claims (1)

A method for producing vegetable tanning agent by extracting vegetable tannin-containing raw materials with hot water, characterized in that cotton stalks are used as vegetable tannin-containing raw materials, and extraction is carried out in the presence of ethylenediamine in an amount of 3.0-5.0% by weight of the raw material, after which filtration is additionally performed , settling, concentration and drying of the extract.