RU2386702C1 - Method of tanning hides - Google Patents

Abstract

FIELD: chemistry, hide tanning.

SUBSTANCE: method relates to tanning hides and can be used in the leather industry. Animal hides are treated with a solution of chrome tanning agent with addition of an activating organic agent in form of aminocapronic acid at concentration of 8-12 g/l.

EFFECT: improved strength properties of hides and environmentally safe method.

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Description

The invention relates to the chemical treatment of hides and is intended for tanning animal skins with the achievement of increased skin strength and increased environmental safety of production.

There is a method of producing a doubled semi-finished product from cattle using a tannin solution including a chrome tanning agent, neutralizing agents and C ₄ -C ₆ aliphatic carboxylic acids with the addition of sodium polymethylene naphthalene sulfonate and sodium lignosulfonate [RF Patent No. 2031956, cl. C14C 3/06, 1995].

The disadvantages of the method include the inability to obtain skin with high strength properties, the ingress of toxic sulfonates into wastewater.

A known method of tanning skins using a tannin based on the reaction products of polyoxymethylene with a secondary amine and alcohol and after the reaction in the form of tertiary amines and ether groups [US Patent No. 4270912, cl. C14C 3/06, 1981].

According to this tanning method, the skin strength is at the permissible limit (0.8 kgf / mm ² ), and the formation of tertiary amines leads to wastewater pollution with toxic amines.

A known method of tanning hides (prototype) based on a chrome tanning agent using poly-2-hydroxypropanammonium chloride as an activating polymer agent at a concentration of 0.005-0.01 g / l. The introduction of the specified polymer agent accelerates the tanning process (RF Patent No. 2028384, CL C14C 3/06, 1995).

The disadvantages of the method include the need to obtain a freshly prepared polymer agent, washing it with acetone or isopropyl alcohol, which leads to atmospheric pollution by vapors of organic solvents, as well as insufficient tensile strength of the samples (0.54-0.96 kgf / mm ² ) with an elongation of 29 32%

The technical result of the invention consists in the use of an additive that activates the tanning process and promotes the production of leathers with a strap strength of 1.27-1.66 kgf / mm ² with an extension of 32-36.5%, allowing the use of leather for the manufacture of clothing, aminokapron acid or gelatin at concentrations of 8-12 g / l. Given the low toxicity of the reagents used and their non-volatility, the environmental safety of production is increased.

The essence of the invention lies in the fact that in the method of tanning hides by treating them with a solution of chrome tanning agent with the sequential introduction of a neutralizing and activating organic agent, aminocaproic acid or gelatin, non-toxic substances widely used in the production of chemical fibers, organic synthesis, pharmaceuticals or in the food industry, at a concentration of 8-12 g / l. When using conventional neutralizing agents, such as soda, the tanning process ends in 6-10 hours to obtain a skin with a strength of up to 1.06 kgf / mm ² with elongation up to 36.5% with a thickness of 0.6-0.78 mm, which allows you to use leather for making clothes and shoes.

8-12 g / l of aminocaproic acid (or gelatin) was introduced into the tanning solution with a chromium tanning agent content of 20-30 g / l with stirring, half of the tanning solution was fed into the spinning drum with the goal, and after another hour of processing, the other half, with tanning temperatures (26-32 ° C). Two hours after the start of the process, a neutralizing agent was introduced - a soda solution, half of the total consumption of soda, another hour - the second half of a solution of a neutralizing agent. Tanning ends after 8 hours from the start of tanning with a positive test for instrumentation. Further, washing of the doubled-out goo was carried out, stretching and mechanical operations. The tanning processes were carried out at a liquid coefficient of 0.6, the consumption of chrome tanning agent (in terms of Cr ₂ O ₃ ) of 1.5% by weight of the gol. The initial soda solution fed to the tanning drum had a concentration of 171 g / l. At concentrations of aminocaproic acid or gelatin less than 8 g / l, the duration of the process increases, and at concentrations above 12 g / l, skin quality indicators do not improve, which limits the advisability of increasing the concentration of the additive.

A distinctive feature of the proposed method is that the introduction of aminocaproic acid or gelatin into it allows you to get skin with high strength properties with significant lengthening due to the formation of additional cross-links between the functional groups of the protein and the compounds resulting from the interaction of chromium (III) complexes with active groups aminocaproic acid or gelatin in the presence of neutralizing agents.

Example 1. According to the specified mode, the goatskin skin was blown at a tanning agent concentration of 20 g / l and aminocaproic acid 8 g / l. After 8 hours of tanning, the skin thickness was 0.6 mm with a tensile strength of 1.66 kgf / mm ² and an elongation of 32% against a permissible 0.8 kgf / mm ² .

Example 2. When tanning a goat with a solution with a tanning agent concentration of 30 g / l and aminocaproic acid 12 g / l, the skin thickness was 0.78 mm with a tensile strength of 1.53 kgf / mm ² and an elongation of 34.5%.

Example 3. When tanning sheepskin with a tannin solution with a tanning agent concentration of 30 g / l and gelatin 8 g / l, leather was 0.65 mm thick with a tensile strength of 1.27 kgf / mm ² and an elongation of 36.5%.

Example 4. When tanning sheepskin with a solution of tanning agent with a gelatin concentration of 12 g / l after 8 hours, a skin thickness of 0.65 mm was obtained with a tensile strength of 1.35 kgf / mm ² and an elongation of 32.5%.

Example 5. When tanning raw materials of light sowing at a tanning agent concentration of 30%, aminocaproic acid 10 g / l, a skin thickness of 0.94 mm was obtained with a tensile strength of 1.32 kgf / mm ² and an elongation of 32%.

The skin thickness should be in the range of 0.6-1.2 mm, the tensile strength of the strap is not less than 0.8 kgf / mm ² with an elongation of 30-40%.

Claims (1)

The method of tanning hides by treating them with a solution of chrome tanning agent with the introduction of an activating organic agent, characterized in that aminocaproic acid is used as an organic agent at a concentration of 8-12 g / l.