TW201309864A - Depilation method of animal skin - Google Patents

Abstract

A depilation method of animal skin is to firstly add the animal skin into a rotary drum or a paddle vat, and add 100-300wt% of water and 0.1-0.5wt% of a degreasing agent, rotate, pour the water out; add 100-300 wt% of water, 0.1-2 wt% of a basifying agent, 0.1-0.5 wt% of a Wetting Agent, 0.1-0.5wt% of a degreasing agent, 0.1-1 wt% of a first composite protease, and 0.1-1 wt% of a lipase, rotate; add 0.05-0.3 wt% of a sterilizer, rotate; intermittently rotate for 5-24 hours, pour the water out; add 30-300 wt% of water, 0.1-3 wt% of non-sulfide depilatories, 0.1-0.5 wt% of a degreasing agent, 0.1-1 wt% of a second composite protease, and 0.1-1 wt% of lipase, rotate; intermittently rotate to add 0.2-2 wt% of sodium hydroxide twice or four times while in rotation; add 0.3-1.8 wt% of sodium sulfide, rotate, stop; intermittently rotate, add 0.5-3 wt% of sodium hydroxide twice or five times while in rotation; and add 30-150 wt% of water, pour the water out. The method of the present invention can conventionally reduce the amount of lime and sulfide pollution in waste water.

Description

Method for depilation of animal skin

The present invention relates to a method for depilating animal skin, and more particularly to a method for depilating animal skin which does not use lime and which greatly reduces the use of alkali sulfide, thereby greatly reducing waste of the tanning process and its degree of contamination.

The leather is produced by the tanning of the fur of the animal. Before the tanning, the main process of pre-soaking, soaking, depilating and deliming is required. The purpose is to remove the salt and decontamination of the obtained animal skin and restore the animal skin properly. The water content and the degree of expansion, and maintain its freshness, the most critical step is the hair removal ash, the quality of the cortex in addition to the conditions of the animal skin itself, the step of hair removal ash is also a decisive factor, this step The purpose is to destroy the hair of the original skin, open the collagen fibers of the leather and emulsify the natural animal oil of the original skin to facilitate the subsequent tanning process. Therefore, in short, the anterior procedure in the tanning process is mainly to depilate the animal skin (including raw and salted skin) and open the leather fiber to a certain extent for the next stage of the procedure.

In recent decades, in the traditional tanning process, the main basic raw materials for animal skin depilation and leather fiber opening technology are the use of large amounts of lime and sulfides. The use of sulfides and limes has the advantages of low cost, high efficiency and easy control. However, the disadvantage is that the solubility of lime itself is low (15~25%), so that there are a large amount of precipitates in the wastewater due to the insolubilization of lime, and the high chemical oxygen demand (COD) due to the large amount of sulfides (Chemical Oxygen Demand, COD) ), as well as Biochemical Oxygen Demand (BOD), which is caused by sulfides, which are difficult to decompose organic matter. Therefore, the animal skin hair removal program is the main producer of COD, BOD and solid waste in the overall leather process.

In the past, there have been many different process technologies such as oxidative hair removal, enzymatic hair removal, and the organic amines and organic sulfur hair removal methods that are currently used. At present, the enzyme hair removal method and the organic amine and organic sulfur hair removal method are mainly used to solve the above problems, especially the enzyme hair removal method, which has been proposed and discussed in recent years. Conventional enzymatic hair removal methods have been proposed, but due to their use of a single protease, the operation is cumbersome for conditional control and practical operation, and often causes damage to the grain surface and excessive looseness of the leather fibers.

The main components of animal skin are protein and fat. Therefore, in the processing technology of animal skin hair removal and leather fiber opening, it is necessary to partially decompose and remove fat, and part of non-structural proteins such as albumin, globulin and glycoprotein. Decomposition and removal, and then the decomposition of structural proteins such as collagen, elastin, keratin, etc., can achieve the ideal results of animal skin hair removal and leather fiber opening, but the traditional process still uses lime and sulfide (sodium sulfide And sodium hydrosulfide) as the main raw material for the decomposition of protein and open leather fiber, the enzyme is still used as an auxiliary. The traditional organic amine and organic sulfur hair removal method is difficult to reduce COD and solid waste.

Therefore, there is a need for a method for depilating animal skin which can reduce the degree of pollution of wastewater in the process and effectively maintain the quality of leather fibers.

The main object of the present invention is to provide a method for depilating animal skin to depilate animal skin. The method for depilating animal skin of the present invention comprises the following steps, wherein the materials other than animal skin are used in the same amount. The weight percentage (wt%) of the skin is calculated:

(a) After adding the animal skin to the drum or grooving, add 100~300 wt% of water and 0.1~0.5 wt% of degreasing agent, adjust the temperature to 20~30 °C, rotate for 20~100 minutes, and pour out the water.

(b) Adding water 100~300 wt%, extracting agent 0.1~2 wt%, rewetting agent 0.1~0.5 wt%, degreasing agent 0.1~0.5 wt%, first complex protease 0.1~1 wt% and lipase 0.1 ~1 wt%, adjust the temperature to 20~30 degrees, pH to 8~11, rotate for 60~200 minutes.

(c) Add bactericide 0.05~0.3 wt% and rotate for 10~30 minutes.

(d) Turn the water out intermittently for 5 to 24 hours.

(e) adding 30~300 wt% of water, adding 0.1~3 wt% of non-sulfiding depilatory agent, 0.1~0.5 wt% of degreaser, 0.1~1 wt% of second complex protease and 0.1~1 wt% of lipase, adjusting temperature Turn to 5~20°C for 5~20 minutes.

(f) Using intermittent rotation, add 0.2~2 wt% of sodium hydroxide in 2~4 times during rotation, adjust the pH to 9~13, and rotate for 60~100 minutes.

(g) Add 0.3 to 1.8 wt% of sodium sulfide, rotate for 30 to 60 minutes, and stop for 30 to 60 minutes.

(h) Using intermittent rotation, rotating for 10 minutes per hour, adding 0.5 to 3 wt% of sodium hydroxide in 2 to 5 times during rotation.

(i) Add 30~150 wt% of water and intermittently rotate for 5~24 hours to pour out the water.

The rewetting agent is at least one of ethanolamine, diethanolamine, triethanolamine, urea, mercapto compound, and fatty alcohol polyoxyethylene ether.

The first composite protease and the second composite protease are respectively derived from at least one of a composite protease of an animal, a plant, and a microorganism, and the first composite protease and the second composite protease are identical to each other or different from each other.

The lipase is derived from at least one of an animal, a plant, or a microbial lipase.

The non-vulcanized depilatory agent is a mercapto group-containing compound depilatory agent which is a combination of a mercapto compound and at least one selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, urea, and a fatty alcohol polyoxyethylene ether.

In the above steps (a) to (i), in the step (h), the circulating filter is performed while the rotation is being performed or the circulating filter is not performed.

The method for depilating animal skin according to the present invention, the applicable animal skin includes raw hide or salted skin.

Therefore, the method for depilating the animal skin of the present invention does not use lime and uses only a small amount of alkali sulfide, which greatly reduces the environmental pollution caused by the use of a large amount of lime and alkali sulfide in the conventional process.

The embodiments of the present invention are described in more detail below, and can be implemented by those skilled in the art after studying this specification.

The invention discloses a method for depilating animal skin to depilate the animal skin, and the method for depilating the animal skin of the invention comprises the following steps, wherein the materials other than the animal skin are used in the weight of the animal skin used. Percentage (wt%) to calculate:

(a) After adding the animal skin to the drum or grooving, add 100~300 wt% of water and 0.1~0.5 wt% of degreasing agent, adjust the temperature to 20~30 °C, rotate for 20~100 minutes, and pour out the water.

(b) Adding water 100~300 wt%, extracting agent 0.1~2 wt%, rewetting agent 0.1~0.5 wt%, degreasing agent 0.1~0.5 wt%, first complex protease 0.1~1 wt% and lipase 0.1 ~1 wt%, adjust the temperature to 20~30 degrees, pH to 8~11, rotate for 60~200 minutes.

(c) Add bactericide 0.05~0.3 wt% and rotate for 10~30 minutes.

(d) Turn the water out intermittently for 5 to 24 hours.

(e) adding 30~300 wt% of water, adding 0.1~3 wt% of non-sulfiding depilatory agent, 0.1~0.5 wt% of degreaser, 0.1~1 wt% of second complex protease and 0.1~1 wt% of lipase, adjusting temperature Turn to 5~20°C for 5~20 minutes.

(f) Using intermittent rotation, add 0.2~2 wt% of sodium hydroxide in 2~4 times during rotation, adjust the pH to 9~13, and rotate for 60~100 minutes.

(g) Add 0.3 to 1.8 wt% of sodium sulfide, rotate for 30 to 60 minutes, and stop for 30 to 60 minutes.

(h) Using intermittent rotation, rotating for 10 minutes per hour, adding 0.5 to 3 wt% of sodium hydroxide in 2 to 5 times during rotation.

(i) Add 30~150 wt% of water and intermittently rotate for 5~24 hours to pour out the water.

In the above steps (a) to (d), the procedure of water immersion using the rewetting agent, the first composite protease and the lipase is used, and the steps (e) to (i) are carried out without using lime. In the alkaline environment, a non-sulfiding depilatory agent, a degreasing agent, a second composite protease, a small amount of alkali sulfide and a sodium hydroxide expansion agent are used for depilation, and the subsequent tanning process is started by a deliming step, and is prepared according to a normal process. In the deliming step, the amount of ammonium salt used is reduced by 15-50%, or the amount of the deashing agent can be reduced by 10-30%, so that the method of depilating the animal skin with low sulfur and no lime can achieve the purpose of reducing environmental pollution.

The rewetting agent is at least one of ethanolamine, diethanolamine, triethanolamine, urea, mercapto compound, and fatty alcohol polyoxyethylene ether.

The first composite protease and the second composite protease are respectively derived from at least one of a composite protease of an animal, a plant, and a microorganism, and the first composite protease and the second composite protease are identical to each other or different from each other.

The lipase is derived from at least one of an animal, a plant, or a microbial lipase.

The non-vulcanized depilatory agent is a mercapto group-containing compound depilatory agent which is a combination of a mercapto compound and at least one selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, urea, and a fatty alcohol polyoxyethylene ether.

In the above steps (a) to (i), in the step (h), the circulating filter is performed while the rotation is being performed or the circulating filter is not performed.

The method for depilating animal skin according to the present invention, the applicable animal skin includes raw hide or salted skin.

Regarding the steps of the method for depilating animal skin as described above, several examples are given below to illustrate the practical application of the present invention.

Example 1: Method for removing hair from animal skin of American beef

(a) US cowhide 100kg, into the drum, pre-soaked water (150kg of water and 0.2kg of degreaser, adjusted to 24 ° C, rotated for 60 minutes), poured water.

(b) 150 kg of water, 0.2 kg of INVIGAL NS (alkaline complex protease, Yotai Industrial Co., Ltd.), 0.1 kg of INVIGAL DG (alkaline lipase, Yotai Industrial Co., Ltd.), 0.4 kg of sodium carbonate, and rewet 0.15 kg of agent and 0.2 kg of degreaser, adjusted to 24 ° C, and rotated for 120 minutes.

(c) Add 0.1 kg of fungicide and rotate for 15 minutes.

(d) Adjust to intermittent rotation, rotate for 5 minutes per hour, about 16 hours, pour water.

(e) Add 80 kg of water, add 1.0 kg of SIRO NL1 (non-vulcanized depilatory agent, Yotai Industrial Co., Ltd.), degreaser 0.2 kg, SIRO NL (alkaline complex protease, Yotai Industrial Co., Ltd.) 0.75 kg and INVIGAL DG (lipase, Yotai Industrial Co., Ltd.) 0.2kg, adjusted to 25 ° C, and rotated for 10 minutes.

(f) Add sodium hydroxide in three portions, 0.3 kg each time, a total of 1.2 kg, and rotate for 15 minutes after each addition of sodium hydroxide, and stop for 10 minutes.

(g) Add 1.2 kg of sodium sulfide, rotate for 30 minutes, and stop for 30 minutes.

(h) Using intermittent rotation, rotating for 10 minutes per hour, adding sodium hydroxide in three portions, 0.3 kg each time, a total of 0.9 kg, and adding when rotating.

(i) Add 30 kg of water, intermittently rotate, rotate for 5 minutes per hour, about 18 hours, pour water.

Example 2: Method for depilation of animal skin of sofa leather Australian cattle

(a) Australian cowhide 100kg, into the drum, pre-soaked water (150kg of water and degreaser 0.3kg, adjusted to 24 ° C, rotated for 60 minutes), poured water.

(b) 160 kg of water, 0.2 kg of INVIGAL NS (alkaline complex protease, Yotai Industrial Co., Ltd.), 0.2 kg of INVIGAL DG (alkaline lipase, Yotai Industrial Co., Ltd.), 0.6 kg of sodium carbonate, and rewet 0.15kg of agent and 0.3kg of degreaser, adjust the temperature to 24 ° C, rotate for 120 minutes

(c) Add 0.15 kg of fungicide and rotate for 15 minutes.

(d) Adjust to intermittent rotation, rotate for 5 minutes per hour, about 18 hours, pour water.

(e) Add 80 kg of water, add 1.0 kg of SIRO NL1 (non-vulcanized depilatory agent, Yotai Industrial Co., Ltd.), degreaser 0.2 kg, SIRO NL (alkaline complex protease, Yotai Industrial Co., Ltd.) 0.85 kg and INVIGAL DG (Lactase, Yotai Industrial Co., Ltd.) 0.3kg, adjusted to 25 ° C, and rotated for 10 minutes.

(f) Add sodium hydroxide in three portions, 0.3 kg each time, a total of 1.2 kg, and rotate for 15 minutes after each addition of sodium hydroxide, and stop for 10 minutes.

(g) Add 1.2 kg of sodium sulfide, rotate for 30 minutes, and stop for 30 minutes.

(h) Using intermittent rotation, rotating for 10 minutes per hour, adding sodium hydroxide in three portions, 0.3 kg each time, a total of 0.9 kg, and adding when rotating.

(i) Add 50 kg of water, intermittently rotate, rotate for 5 minutes per hour, about 22 hours, pour water.

Example 3: Method for removing hair from animal skin of Japanese pig skin

(a) Japanese pig skin 100kg, into the drum, pre-soaked water (150kg of water and degreaser 0.3kg, adjusted to 24 ° C, rotated for 80 minutes), poured water.

(b) Add 200kg of water, add INVIGAL NS (alkaline complex protease, Yotai Industrial Co., Ltd.) 0.3kg, INVIGAL DG (alkaline lipase, Yotai Industrial Co., Ltd.) 0.2kg, sodium carbonate 1.0kg, rewet 0.2 kg of the agent and 0.4 kg of the degreaser were adjusted to 25 ° C and rotated for 160 minutes.

(c) Add 0.2 kg of fungicide and rotate for 15 minutes.

(d) Adjust to intermittent rotation, rotate for 5 minutes per hour, about 18 hours, pour water.

(e) Add 80 kg of water, add 1.0 kg of SIRO NL1 (non-vulcanized depilatory agent, Yotai Industrial Co., Ltd.), degreaser 0.3 kg, SIRO NL (alkaline complex protease, Yotai Industrial Co., Ltd.) 0.85 kg and INVIGAL DG (Lactase, Yotai Industrial Co., Ltd.) 0.3kg, adjusted to 25 ° C, and rotated for 10 minutes.

(f) Add sodium hydroxide in three portions, 0.3 kg each time, a total of 1.2 kg, and rotate for 15 minutes after each addition of sodium hydroxide, and stop for 10 minutes.

(g) 1.6 kg of sodium sulfide was added, rotated for 30 minutes, and stopped for 30 minutes.

(h) Using intermittent rotation, rotating for 10 minutes per hour, adding sodium hydroxide in three portions, 0.3 kg each time, a total of 1.2 kg, and adding when rotating.

(i) Add 50 kg of water, intermittently rotate, rotate for 5 minutes per hour, about 22 hours, pour water.

Example 4: Method for removing hair from animal skin of Japanese pig skin

(a) Japanese pig skin 100kg, into the drum, pre-soaked water (150kg of water and degreaser 0.3kg, adjusted to 24 ° C, rotated for 80 minutes), poured water.

(b) Add 200kg of water, add INVIGAL NS (alkaline complex protease, Yotai Industrial Co., Ltd.) 0.3kg, INVIGAL DG (alkaline lipase, Yotai Industrial Co., Ltd.) 0.2kg, sodium carbonate 1.0kg, rewet 0.2 kg of the agent and 0.4 kg of the degreaser were adjusted to 25 ° C and rotated for 180 minutes.

(c) Add 0.2 kg of fungicide and rotate for 15 minutes.

(d) Adjust to intermittent rotation, turn 5 minutes per hour, about 20 hours, pour water.

(e) Add 80 kg of water, add 1.0 kg of SIRO NL1 (non-vulcanized depilatory agent, Yotai Industrial Co., Ltd.), degreaser 0.3 kg, SIRO NL (alkaline complex protease, Yotai Industrial Co., Ltd.) 0.85 kg and INVIGAL DG (Lactase, Yotai Industrial Co., Ltd.) 0.3kg, adjusted to 25 ° C, and rotated for 10 minutes.

(f) Add sodium hydroxide in three portions, 0.3 kg each time, a total of 1.2 kg, and rotate for 15 minutes after each addition of sodium hydroxide, and stop for 10 minutes.

(g) 1.6 kg of sodium sulfide was added, rotated for 30 minutes, and stopped for 30 minutes.

(h) Using intermittent rotation, rotating for 10 minutes per hour, adding sodium hydroxide in three portions, 0.3 kg each time, a total of 1.2 kg, and adding when rotating.

(i) Add 50 kg of water, intermittently rotate, rotate for 5 minutes per hour, about 22 hours, pour water.

Example 5: Method for depilation of animal skin of suede goatskin

(a) 100kg goat skin, into the drum, pre-soaked water (110kg of water and 0.3kg of degreaser, adjusted to 24 ° C, rotated for 80 minutes), poured into water.

(b) 200 kg of water, 0.3 kg of INVIGAL NS (alkaline complex protease, Yotai Industrial Co., Ltd.), 0.2 kg of INVIGAL DG (alkaline lipase, Yotai Industrial Co., Ltd.), 0.8 kg of sodium carbonate, and rewet 0.2 kg of the agent and 0.4 kg of the degreaser were adjusted to 25 ° C and rotated for 120 minutes.

(c) Add 0.15 kg of fungicide and rotate for 15 minutes.

(d) Adjust to intermittent rotation, turn 5 minutes per hour, about 16 hours, pour water.

(e) Add 80 kg of water, add 1.0 kg of SIRO NL1 (non-vulcanized depilatory agent, Yotai Industrial Co., Ltd.), degreaser 0.3 kg, SIRO NL (alkaline complex protease, Yotai Industrial Co., Ltd.) 0.85 kg and INVIGAL DG (Lactase, Yotai Industrial Co., Ltd.) 0.3kg, adjusted to 25 ° C, and rotated for 10 minutes.

(f) Add sodium hydroxide in three portions, 0.3 kg each time, a total of 0.9 kg, and rotate for 15 minutes after each addition of sodium hydroxide, and stop for 10 minutes.

(g) 1.6 kg of sodium sulfide was added, rotated for 30 minutes, and stopped for 30 minutes.

(h) Using intermittent rotation, rotating for 10 minutes per hour, adding sodium hydroxide in three portions, 0.3 kg each time, a total of 1.2 kg, and adding when rotating.

(i) Add 50 kg of water, intermittently rotate, rotate for 5 minutes per hour, about 22 hours, pour water.

Example 6: Method for removing hair from animal skin of garment leather sheepskin

(a) 100 kg of sheep skin, into the drum, pre-soaked water (110 kg of water and 0.3 kg of degreaser, adjusted to 24 ° C, rotated for 80 minutes), poured water.

(b) 200 kg of water, 0.2 kg of INVIGAL NS (alkaline complex protease, Yotai Industrial Co., Ltd.), 0.2 kg of INVIGAL DG (alkaline lipase, Yotai Industrial Co., Ltd.), 0.8 kg of sodium carbonate, and rewet 0.2 kg of the agent and 0.4 kg of the degreaser were adjusted to 25 ° C and rotated for 120 minutes.

(c) Add 0.15 kg of fungicide and rotate for 15 minutes.

(d) Adjust to intermittent rotation, turn 5 minutes per hour, about 16 hours, pour water.

(e) Drumming, alkali stripping, drumming, adding 150kg of water, adding SIRO NL1 (non-vulcanized depilatory agent, Yotai Industrial Co., Ltd.) 1.0kg, degreaser 0.3kg, SIRO NL (alkaline complex protease, Yotai Industrial Co., Ltd.) 0.6kg and INVIGAL DG (lipase, Yotai Industrial Co., Ltd.) 0.3kg, adjusted to 25 ° C, rotated for 10 minutes.

(f) Add sodium hydroxide in three portions, 0.3 kg each time, a total of 0.9 kg, and rotate for 15 minutes after each addition of sodium hydroxide, and stop for 10 minutes.

(g) 1.6 kg of sodium sulfide was added, rotated for 30 minutes, and stopped for 30 minutes.

(h) Using intermittent rotation, rotating for 10 minutes per hour, adding sodium hydroxide in three portions, 0.3 kg each time, a total of 0.9 kg, and adding when rotating.

(i) Add 50 kg of water, intermittently rotate, rotate for 5 minutes per hour, about 22 hours, pour water.

Therefore, the method for depilating animal skin of the present invention is characterized in that, in the anterior procedure of the tanning process, no lime is used and only a small amount of alkali sulfide is used to complete the steps of depilation of the animal skin and opening of the leather fiber, thereby comparing The traditional hair removal process, the invention greatly reduces the environmental pollution caused by the use of a large amount of lime and alkali sulfide in the conventional process, and the COD and suspended solids in the wastewater are greatly reduced.

Another feature of the present invention is that the present invention uses a combination of chemical and biotechnological methods, is suitable for various leather types, various hair removal and leather fiber opening steps, and the method used in the present invention can increase the softness of the leather. The rate of leather removal is increased, so that the amount of chromium used in the chrome tanning wastewater can be reduced in the next chrome tanning process.

The above is only a preferred embodiment for explaining the present invention, and is not intended to limit the present invention in any way, and any modifications or alterations to the present invention made in the spirit of the same invention. All should still be included in the scope of the intention of the present invention.

Claims (8)

A method for depilating animal skin to depilate an animal skin, the method for depilating the animal skin comprising the following steps, wherein the amount of material other than the animal skin is calculated by weight percentage (wt%) of the animal skin : (a) After adding the animal skin to the drum or grooving, add 100~300 wt% of water and 0.1~0.5 wt% of degreasing agent, adjust the temperature to 20~30 °C, turn for 20~100 minutes, pour water (b) adding water 100~300 wt%, extracting agent 0.1~2 wt%, rewetting agent 0.1~0.5 wt%, degreasing agent 0.1~0.5 wt%, first complex protease 0.1~1 wt% and fat Enzyme 0.1~1 wt%, adjust the temperature to 20~30 degrees, pH to 8~11, rotate for 60~200 minutes; (c) add fungicide 0.05~0.3 wt%, rotate for 10~30 minutes; (d) intermittent Rotate for 5~24 hours, pour out water; (e) add 30~300 wt% of water, add 0.1~3 wt% of non-sulfiding depilatory agent, 0.1~0.5 wt% of degreaser, 0.1~1 wt% of second complex protease And lipase 0.1~1 wt%, adjust the temperature to 20~30 °C, rotate for 5~20 minutes; (f) use intermittent rotation, add 0.2~2 wt% of sodium hydroxide in 2~4 times during rotation, Adjust pH to 9~13, rotate for 60~100 minutes; (g) add sodium sulfide 0.3 ~1.8 wt%, rotate for 30~60 minutes, stop for 30~60 minutes; (h) use intermittent rotation, rotate for 10 minutes per hour, add 0.5~3 wt% of sodium hydroxide in 2~5 times during rotation; And (i) adding 30~150 wt% of water, intermittently rotating for 5~24 hours, pouring out the water. The method for depilating animal skin according to claim 1, wherein the rewetting agent is at least one of ethanolamine, diethanolamine, triethanolamine, urea, mercapto compound, and fatty alcohol polyoxyethylene ether. The method for depilating animal skin according to claim 1, wherein the first composite protease and the second composite protease are derived from at least one of a composite protease of an animal, a plant, and a microorganism. The method of depilating animal skin according to claim 3, wherein the first composite protease and the second composite protease are identical to each other or different from each other. The method for depilating animal skin according to claim 1, wherein the lipase is derived from at least one of an animal, a plant, or a microbial lipase. The method for depilating animal skin according to claim 1, wherein the non-vulcanized depilatory agent is a mercapto compound-containing depilatory agent, which is a mercapto compound and is selected from the group consisting of ethanolamine, diethanolamine, triethanolamine, urea, and fatty alcohol polyoxygen. A combination of at least one of vinyl ethers. The method for depilating animal skin according to claim 1, wherein in the step (h), the filter is circulated or the filter is not circulated while rotating. The method of depilating animal skin according to claim 1, wherein the animal skin comprises a raw hide or a salted peel.