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Raw skin hair saving and removing method using neutral protease and chemical substances

A neutral protease, hair-preserving and depilatory technology, which can be used in the treatment of small hides/big hides/leather/fur, chemical treatment before tanning, chemical treatment of small hides/big hides/leather skins/furs, etc., and can solve the problem of reducing sulfides Pollution, difficult to remove the epidermis, easy to shed hair and other problems, to achieve the effect of preventing excessive lime hair protection, high product quality and safety, and low price

Active Publication Date: 2015-05-20
SICHUAN UNIV
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  • Summary
  • Abstract
  • Description
  • Claims
  • Application Information

AI Technical Summary

Problems solved by technology

The method can solve the problem that the existing enzyme depilation method is easy to remove hair endlessly, the enzyme depilation method and the enzyme-sulfide synergistic depilation method cause grain surface damage or loose surface, the chemical hair preservation depilation method is easy to protect excessive hair, and the chemical hair preservation and depilation method with less sulfur It is difficult to remove the technical problem of the epidermis, and achieve the same or even better hair removal effect than the ash-alkali method, while greatly reducing sulfide pollution

Method used

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Examples

Experimental program
Comparison scheme
Effect test

Embodiment 1

[0031] (1) Remove the epidermis: Put the cowhide that has been soaked and de-fleshed according to the routine into the drum, add 100wt% water, the pH of the bath solution is 7.5, adjust the temperature to 22°C, add Bacillus subtilis neutral protease 20 units of protease activity / g skin, rotate for 35min;

[0032] (2) Inactivation of protease and hair protection: add 1.0wt% lime to the above bath liquid, rapidly increase the pH of the bath liquid to 12.2 to inactivate neutral protease, turn on for 30 minutes, stop for 30 minutes, and achieve the effect of hair protection;

[0033] (3) Hair removal: Drain part of the bath liquid, the remaining 50wt% of water, and then add industrial grade sodium sulfide (flaky, Na 2 S content 60%), so that the total S 2- The dosage is 0.2wt%, and it is rotated for 90 minutes to make all the hairs fall off and filter the hairs;

[0034] (4) Disperse collagen fibers: add 2.0wt% lime to the above hair removal bath, turn for 10 minutes, add 50wt%...

Embodiment 2

[0036] (1) Remove the epidermis: Put the cowhide that has been soaked and de-fleshed according to the routine into the drum, add 100wt% water, the pH of the bath solution is 8.0, adjust the temperature to 25°C, add actinomycete neutral protease 20 units of protease activity / g skin, rotate for 40min;

[0037] (2) Inactivation of protease and hair protection: add 1.5wt% lime to the above bath liquid, rapidly increase the pH of the bath liquid to 12.6 to inactivate neutral protease, turn on for 30 minutes, stop for 30 minutes, and achieve the effect of hair protection;

[0038] (3) Hair removal: Drain part of the bath liquid, leaving 75wt% of water, and then add industrial grade sodium sulfide (flaky, Na 2 S content 60%) and industrial grade sodium hydrosulfide (flaky, NaHS content 70%), of which S of sodium sulfide 2- The dosage is 0.1wt%, the S of sodium hydrosulfide 2- The dosage is 0.2wt%, and it is rotated for 75 minutes to make all the hairs fall off and filter the hairs...

Embodiment 3

[0041] (1) Remove the epidermis: Put the goat skin that has been soaked and de-fleshed according to the routine into the drum, add 100wt% water, the pH of the bath solution is 7.0, adjust the temperature to 25°C, and add porcine trypsin 25 protease activity units / g Skin, turn 50min;

[0042] (2) Inactivation of protease and hair protection: add 1.0wt% lime to the above bath liquid, rapidly increase the pH of the bath liquid to 12.0 to inactivate neutral protease, and turn it for 90 minutes to achieve the effect of hair protection;

[0043] (3) Hair removal: add industrial grade sodium hydrosulfide (flaky, NaHS content 70%), so that the total S 2- The dosage is 0.4wt%, and it is rotated for 60 minutes to make all the hairs fall off and filter the hairs;

[0044] (4) Disperse collagen fibers: add 2.0wt% lime to the above hair removal bath, turn for 10 minutes, add 100wt% water, turn for 10 minutes, stop for 20 minutes, add 1.0wt% sodium silicate, turn for 10 minutes, stop for 2...

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Abstract

The invention discloses a raw skin hair saving and removing method using neutral protease and chemical substances. The method is characterized by comprising the following steps: firstly treating raw skin for 25-55 minutes at the pH of 7.0-8.5 by using the neutral protease so as to damage and remove the surface skin; increasing the pH of bath foam to be over 12 by using lime, and inactivating the neutral protease, so that the risk of damaging the skin collagen through the protease is eliminated, the hair is protected, and finally the aim of protecting and removing the hair is achieved by using a small amount of sulfides. According to the method, the technical problems that the hair is incompletely removed in the conventional enzyme unhairing method, the grain side is damaged or loosened due to the enzyme unhairing method and enzyme-sulfide cooperative unhairing method, the hair is easily removed excessively in a chemical hair protecting and removing method and the surface skin is difficultly removed in a sulfur chemical hair protecting and removing method can be solved. Compared with a limed alkali method, the method has the advantages that the grain side on unhaired naked skin is clean and smooth, the sulfides, suspended solids and organic pollutants in wastewater are greatly reduced, and the method is a raw skin hair removing method which is easily controlled in operation, economical and practical and can ensure the product quality safety.

Description

technical field [0001] The invention relates to a method for preserving and depilating raw hides by using neutral protease and chemical substances, belonging to the field of depilating raw hides. Background technique [0002] The main purpose of raw hide hair removal is to remove the hair and epidermis on the hide. At present, tanneries at home and abroad generally use ash-alkali method for hair removal, that is, 2% to 4% sodium sulfide and 6% to 10% lime are used for hair removal. Lime-soda method is recognized as an economical and effective dehairing method in the tannery industry, but it will cause excessive sulfide concentration in tannery wastewater, and produce a large amount of lime sludge that is difficult to handle and hair degradation products that cannot be recycled. Therefore, in order to eliminate or reduce the pollution caused by ash-alkali hair removal, researchers have proposed more environmentally friendly enzyme hair removal methods and chemical hair-prese...

Claims

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Application Information

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Patent Type & Authority Patents(China)
IPC IPC(8): C14C1/06
Inventor 石碧曾运航周建飞王亚楠廖学品张文华曹明蓉
Owner SICHUAN UNIV
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