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Preparation and application of a modified tannic acid chrome tanning auxiliary

A technology of chromium tannin and tanning auxiliaries, which is applied in application, chemical treatment before tanning, small hide/big hide/leather/fur treatment, etc. It can solve the problems of low chrome absorption rate, limited use of chrome tanning auxiliaries, and environmental problems. Pollution and other issues, to achieve the effect of improving absorption rate, less environmental hazards, and improving absorption

Active Publication Date: 2021-08-03
SHAANXI UNIV OF SCI & TECH
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

Moreover, its operation process is simple and its cost is low, so it is favored by many tanneries, but the absorption rate of chromium is relatively low, and a large part of chromium is not utilized, but is directly discharged into the environment. Chromium ions are easily oxidized into hexavalent chromium ions, causing serious pollution to the environment. In my country alone, more than 3,000 tons of chromium are discharged from wastewater every year, so chrome tanning auxiliaries came into being
[0003] However, most of the current research on chrome tanning auxiliaries is based on aldehyde series. With strict environmental protection, the use of such chrome tanning auxiliaries will be limited
Tannic acid is a natural product, and the chrome tanning auxiliaries developed based on tannic acid are environmentally friendly reagents, which are less harmful to the environment. There is no relevant literature published yet.

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0025] Embodiment one, a kind of preparation method of modified tannic acid chrome tanning auxiliary agent, comprises the following steps:

[0026] 1) Dissolve 25g of tannic acid in 120g of deionized water, and neutralize it with anhydrous sodium carbonate at 0°C until the pH is 6.5;

[0027] 2) Dissolve 11g of monochloroacetic acid in 25g of deionized water, and neutralize it with anhydrous sodium carbonate at 0°C until the pH is 6.5;

[0028] 3) Add the above two solutions into a 500mL four-necked flask at the same time, and raise the temperature to 50°C, and add an aqueous solution of sodium hydroxide (mass fraction: 30%) that is equimolar to chloroacetic acid dropwise in 5 times, and add dropwise every 30min Once, after the last dropwise addition, the system was heated up to 60°C, kept warm and reacted, and the pH was tested until the reaction was stopped when the pH was 7 to obtain modified tannic acid chrome tanning auxiliaries, modified tannic acid chrome tanning auxili...

Embodiment 2

[0034] Embodiment two, a kind of preparation method of modified tannic acid chrome tanning auxiliary agent, comprises the following steps:

[0035] 1) 30g of tannic acid was dissolved in 140g of deionized water, and neutralized with anhydrous sodium carbonate at 3°C ​​until the pH was 7;

[0036] 2) Dissolve 16g of monochloroacetic acid in 30g of deionized water, and neutralize it with anhydrous sodium carbonate at 3°C ​​until the pH is 7;

[0037] 3) Add the above two solutions into a 500mL four-necked flask at the same time, and raise the temperature to 50°C, and add an aqueous solution of sodium hydroxide (mass fraction: 30%) that is equimolar to chloroacetic acid dropwise in 5 times, and add dropwise every 30min Once, after the last dropwise addition, the temperature of the system was raised to 60°C, and the reaction was kept for 3 hours, and the modified tannic acid chrome tanning auxiliary was discharged. The modified tannic acid chrome tanning auxiliary had a pH of 7 an...

Embodiment 3

[0043] Embodiment three, a kind of preparation method of modified tannic acid chrome tanning auxiliary agent, comprises the following steps:

[0044] 1) 34g of tannic acid was dissolved in 160g of deionized water, and neutralized with anhydrous sodium carbonate at 5°C until the pH was 7.5;

[0045] 2) Dissolve 22g of monochloroacetic acid in 35g of deionized water, and neutralize it with anhydrous sodium carbonate at 5°C until the pH is 7.5;

[0046] 3) Add the above two solutions into a 500mL four-necked flask at the same time, and raise the temperature to 50°C, and add an aqueous solution of sodium hydroxide (mass fraction: 30%) that is equimolar to chloroacetic acid dropwise in 5 times, and add dropwise every 30min Once, after the last dropwise addition, the temperature of the system was raised to 60°C, and the reaction was kept for 3 hours, and the modified tannic acid chrome tanning auxiliary was discharged. The modified tannic acid chrome tanning auxiliary had a pH of 7 ...

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Abstract

Preparation and application of a modified tannic acid chrome tanning auxiliary agent. The preparation method is to dissolve the polyhydric phenolic compound in the first solvent and neutralize it with an alkaline substance; then dissolve chloroacetic acid in the second solvent , and neutralized with alkaline substances; then the above two solutions are added to the flask at the same time, and the aqueous solution of alkaline substances is added dropwise until the pH is 7 to obtain a modified tannic acid chrome tanning auxiliary; the application method is first Put the limed skins after deliming and softening and washing into the drum, add water and modified tannin chrome tanning auxiliaries, and then rotate; use alkaline substances to adjust the pH to 8.5-9.0, and continue to rotate; then add acidic acid in stages The substance adjusts the pH of the bath solution at 2.5‑3.0, and continues to rotate; then add chrome powder to rotate; use baking soda and prepare an aqueous solution to add in portions, adjust the pH to 3.8‑4.0, rotate again, and add hot water; stop the drum overnight, the next day Take the drum out, put it on the horse and let it stand still; the invention improves the absorption rate of the chrome tanning agent and has little harm to the environment.

Description

technical field [0001] The invention relates to the technical field of chrome tanning auxiliaries, in particular to the preparation and application of a modified tannic acid chrome tanning auxiliaries. Background technique [0002] Chrome tanning can not only endow leather with good physical and mechanical properties, such as: the finished leather has a smooth and fine grain, high Ts, high tensile strength, soft finished leather and washable. Moreover, its operation process is simple and its cost is low, so it is favored by many tanneries, but the absorption rate of chromium is relatively low, and a large part of chromium is not utilized, but is directly discharged into the environment. Chromium ions are easily oxidized into hexavalent chromium ions, causing serious pollution to the environment. In my country alone, more than 3,000 tons of chromium are discharged with wastewater every year, so chrome tanning auxiliaries emerge as the times require. [0003] However, most of ...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C14C1/00C14C1/08C14C3/06
CPCC14C1/00C14C1/08C14C3/06
Inventor 张辉陈博强西怀俞力栋王新科
Owner SHAANXI UNIV OF SCI & TECH