A method for separating sheepskin from wool

Abstract

The present invention belongs to the field of animal skin processing, and discloses a method for separating wool from sheepskin. During the process of wool-skin separation, the sheepskin that has been deeply degreased is first subjected to enzymatic depilation at 15-25 °C. After the protease penetrates into the skin to a depth of 1 / 2-2 / 3 of the thickness of the sheepskin, the temperature is raised to 35-45 °C, and depilation continues until the depilation is completed. During the whole process, the removed wool is discharged in a timely manner. The present invention can solve the technical problems that the surface of the skin and collagen fibers are easily damaged during the enzymatic depilation of existing sheepskin, and problems such as hair perforation and hair ball formation are likely to occur. Moreover, the operation is convenient, the production efficiency is high, the shape of the removed wool is complete, and the recycling rate is high.

Description

Technical Field

[0001] The present invention belongs to the field of animal skin processing, and particularly relates to a method for separating wool from sheepskin. Background Art

[0002] Wool has the advantages of good elasticity, strong hygroscopicity, good warmth retention, etc.; sheepskin is soft in texture, delicate in grain surface, clear and beautiful in skin pattern, and rich in collagen. Efficient separation of wool and sheepskin can provide important processing raw materials for industries such as textile, leather, and food. Existing fur separation technologies mainly include manual hair removal, scalding hair removal, mechanical hair removal, sulfide alkali hair removal, and enzyme hair removal. However, the production efficiency of manual hair removal and scalding hair removal technologies is low; mechanical shearing or plucking technologies cannot completely remove all the hairs on sheepskin alone; sulfide alkali hair removal technology will dissolve wool, making it impossible to recycle, and it causes great environmental pollution. Enzyme hair removal mainly uses protease to catalytically hydrolyze the epidermal layer of animal skin and the connecting proteins between hair roots and hair follicles, weakening the connections between hair roots and hair follicles, hair bulbs and hair papillae, and epidermis and dermis, so that hair and epidermis can fall off from the skin under mechanical action. Therefore, this technology is environmentally friendly and the removed hair is convenient for recycling.

[0003] However, the specificity of the protease used in enzyme hair removal belongs to relative specificity (i.e., bond specificity), rather than absolute specificity (i.e., substrate specificity). That is, while the protease hydrolyzes the connecting proteins between sheepskin hair roots and hair follicles, it will also hydrolyze sheepskin collagen. In addition, the protease has a large relative molecular mass and slow penetration in sheepskin. Coupled with the high catalytic efficiency of the protease, the collagen fibers on the surface layer of sheepskin are exposed to the action of the enzyme for a longer time than those in the middle layer. Therefore, once the operation of enzyme hair removal is slightly careless, it is easy to damage the collagen fibers of sheepskin, especially the collagen fibers on the surface layer of the leather, reducing the quality of the obtained sheepskin.

[0004] In addition, enzyme hair removal is mainly divided into stacked enzyme hair removal and warm-bath enzyme hair removal. Stacked enzyme hair removal is a method of stacking the enzyme-coated or enzyme-rolled leather sheets one by one under natural temperature or temperature-controlled conditions until the hair is completely loosened, and then removing the hair manually or mechanically. This method is simple in operation, easy to control, and low in heat consumption, but has the disadvantages of large floor area, high labor intensity, long hair removal time, and unpleasant smell in the workshop. Warm-bath enzyme hair removal refers to a method of using protease to remove hair from animal skin in a drum. This method has the advantages of short hair removal time, low labor intensity, and small floor area. However, when removing hair, the wool (especially sheep wool) is extremely easy to entangle into balls in the bath solution, and it is difficult to loosen it after recycling.

[0005] In view of this, the present invention is specifically proposed. Summary of the Invention

[0006] The object of the present invention is to overcome the disadvantages or deficiencies existing in the existing sheepskin fur separation technology, and to provide an efficient sheepskin fur separation method that can prevent damage to sheepskin and avoid wool balling.

[0007] To achieve the above object, the technical solution adopted by the present invention is as follows:

[0008] A sheepskin fur separation method. During the fur separation process, the deeply degreased sheepskin is first subjected to enzymatic depilation at 15 - 25 °C. After the protease penetrates into the sheepskin to a depth of 1 / 2 - 2 / 3 of the sheepskin thickness, the temperature is raised to 35 - 45 °C and depilation continues until the depilation is completed. During the whole process, the removed wool is discharged in a timely manner.

[0009] Preferably, the protease is selected from any one or more of microbial protease, animal protease, and plant protease.

[0010] Preferably, any one or more of a surfactant, sodium carbonate, and sodium hydroxide are used to deeply degrease the sheepskin.

[0011] Preferably, the degreasing rate of the deep degreasing is ≥ 80%.

[0012] The present invention also discloses the wool and sheepskin obtained by using any of the above-mentioned sheepskin fur separation methods.

[0013] Compared with the prior art, the present invention has the following beneficial effects:

[0014] 1. The present invention adopts the method of first deep degreasing and then enzymatic depilation. During the fur separation process, the protease is allowed to penetrate into the sheepskin to a depth of 1 / 2 - 2 / 3 of the sheepskin thickness at 15 - 25 °C before raising the temperature for depilation, solving the technical problem that the existing enzymatic depilation technology is prone to damage the sheepskin.

[0015] 2. Before the enzymatic depilation operation, the present invention first fully removes the grease in the sheepskin and timely separates and discharges the removed wool during the enzymatic depilation process, enabling efficient separation of sheepskin and wool, while avoiding wool perforation and wool balling, and improving the quality and efficiency of wool recycling.

[0016] 3. The sheepskin fur separation method provided by the present invention has a simple process, convenient operation, and the removed wool has a complete shape. Detailed implementation mode

[0017] To make the objectives, technical solutions, and advantages of the present invention clearer and more understandable, the present invention will be further described in detail below in conjunction with specific embodiments. It should be understood that these descriptions are merely exemplary and are not intended to limit the scope of the present invention. In addition, in the following description, descriptions of well-known structures and technologies are omitted to avoid unnecessarily confusing the concepts of the present invention. For those not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer are used. Reagents or instruments not specified by the manufacturer are all conventional products that can be obtained through commercial purchase.

[0018] Through a large number of experiments, the applicant found that the higher the temperature of enzyme dehairing, the faster the protease transfers within the sheepskin, but the greater the damage to the sheepskin. After multiple experiments and repeated verification, the applicant found that this is because increasing the temperature contributes relatively more to enhancing the protease activity and relatively less to accelerating the protease transfer within the skin. Therefore, simple high-temperature dehairing is likely to damage the sheepskin, especially the surface of the sheepskin. Specifically, when the temperature rises from 20°C to 35°C, the relative enzyme activity of the protease increases from 28% to 85%, an increase of 57%; while the penetration rate of the enzyme within the skin (penetration for 30 minutes) only increases from 37% to 49%, an increase of only 12%. Therefore, reasonably controlling the action temperature of the protease throughout the enzyme dehairing process is very important for high-quality dehairing of sheepskin.

[0019] In addition, the wool of sheepskin (especially sheepskin) is dense, with a hair diameter of 0.015 - 0.025 mm and a density of 2,500 - 7,900 hairs / cm 2 . During enzyme dehairing in a drum, the wool is extremely likely to entangle with each other or even form balls, making it difficult to utilize efficiently and with high quality after recovery. The applicant's research found that the reasons for the above phenomena are, on the one hand, that the already removed and unremoved hairs are prone to knotting with each other; on the other hand, a large amount of grease is distributed at the hair follicles and sebaceous glands of the sheepskin, which greatly hinders the penetration of the protease and the hydrolysis of the connecting proteins between the hair roots and the hair follicles, resulting in a long required enzyme dehairing time, more prone to hair ball formation, and more likely to damage the skin surface. After multiple experiments and repeated verification, the applicant found that the lower the grease content of the sheepskin, the faster the protease penetrates within the skin, the higher the dehairing efficiency, and the smaller the damage to the sheepskin. Therefore, fully removing the grease of the sheepskin before enzyme dehairing operation and timely separating and discharging the already removed hairs from the drum during the dehairing process are the keys to the high-efficiency enzyme dehairing technology for sheepskin.

[0020] Based on this, the embodiment of the present invention provides a method for separating wool from sheepskin. During the process of wool-skin separation, the sheepskin that has been deeply degreased is first subjected to enzyme dehairing at 15 - 25°C. After the depth of protease penetration into the skin reaches 1 / 2 - 2 / 3 of the sheepskin thickness, the temperature is raised to 35 - 45°C to continue dehairing until dehairing is completed, and the already removed wool is discharged in a timely manner throughout the process.

[0021] The key point of the embodiment of the present invention is to first perform sufficient degreasing treatment on sheepskin, and then add protease to perform enzymatic hair removal at 15-25°C, ensuring that the depth of penetration of enzyme molecules into the skin at low enzyme activity reaches 1 / 2-2 / 3 of the thickness of the sheepskin (reaching the connection between the hair root and the hair follicle), and then raising the temperature to 35-45°C to increase the high activity of protease and achieve rapid hair removal. In addition, in order to achieve the effect of the present invention, during the entire hair removal process, the removed wool needs to be promptly separated and discharged from the drum to avoid hair perforation and hair balling, and finally achieve the purpose of efficient separation of sheepskin and wool and high-quality recycling and utilization.

[0022] For sufficient degreasing, the present invention finds that when the degreasing rate is controlled at 80% or more, the enzymatic hair removal time can be significantly shortened, the hair removal rate of sheepskin can be increased, and thus the damage of protease to the collagen of sheepskin can be reduced.

[0023] The degreasing reagent is a degreasing reagent used in animal skin processing. The specific type and dosage can be determined by those skilled in the art according to the degreasing object, degreasing degree, etc. In some preferred embodiments, any one or more of surfactants, sodium carbonate, and sodium hydroxide are used to perform deep degreasing treatment on the skin.

[0024] The protease is a protease commonly used in animal skin processing. The specific type and dosage can be determined by those skilled in the art according to the hair removal object. In some preferred embodiments, the protease includes any one or more of microbial protease, animal protease, and plant protease.

[0025] The present invention will be further described in detail below with reference to embodiments. The following embodiments are only used to further illustrate the present invention and should not be construed as limiting the protection scope of the present invention. Those skilled in the art can make some non-essential improvements and adjustments to the present invention based on the above-mentioned invention content.

[0026] The calculation formulas for the degreasing rate, protease penetration depth, and hair removal rate used in the following embodiments are as follows: Degreasing rate = (oil content of sheepskin before degreasing - oil content of sheepskin after degreasing) / oil content of sheepskin before degreasing × 100%; Protease penetration depth = thickness of protease penetration into the skin / thickness of the skin; Hair removal rate = area of the hairless part on the surface of the hair-removed naked skin / total area of the surface of the hair-removed naked skin × 100%.

[0027] Example 1

[0028] The following material dosages are all in mass percentage (wt%) of sheepskin.

[0029] Put sheepskin into a drum, add water, surfactant and sodium carbonate for deep degreasing until the degreasing rate reaches 90%; then change the liquid, add 500% water, adjust the temperature to 20°C, add 1% protease preparation (including microbial protease and animal protease), rotate for 60 min, then adjust the temperature to 40°C, and rotate intermittently for (X - 60) min. The total hair removal time is X min (X is shown in Table 1). During this process, use a hair filter to separate and discharge the removed wool in time to obtain wool and dehaired sheepskin.

[0030] Comparative Example 1

[0031] Compared with Example 1, the difference is only that degreasing treatment is not carried out, and the rest of the processes are the same as those in Example 1.

[0032] Comparative Example 2

[0033] Compared with Example 1, the difference is only that the degreasing rate is 30%, and the rest of the processes are the same as those in Example 1.

[0034] Comparative Example 3

[0035] Compared with Example 1, the difference is only that the degreasing rate is 50%, and the rest of the processes are the same as those in Example 1.

[0036] Comparative Example 4

[0037] Compared with Example 1, the difference is only that the degreasing rate is 70%, and the rest of the processes are the same as those in Example 1.

[0038] Comparative Example 5

[0039] Compared with Example 1, the difference is only that the temperature is controlled at 20°C after adding the enzyme preparation, and the rest of the processes are the same as those in Example 1.

[0040] Comparative Example 6

[0041] Compared with Example 1, the difference is only that the temperature is controlled at 40°C after adding the enzyme preparation, and the rest of the processes are the same as those in Example 1.

[0042] Comparative Example 7

[0043] Compared with Example 1, the difference is only that the removed wool is not discharged during the hair removal process, and the rest of the processes are the same as those in Example 1.

[0044] The corresponding hair removal effect tests were carried out on Example 1, Comparative Example 1, Comparative Example 2, Comparative Example 3, Comparative Example 4, Comparative Example 5, Comparative Example 6 and Comparative Example 7, and were characterized by the penetration depth at 60 min after protease addition and rotation, the hair removal rate at 150 min after protease addition and rotation, the time taken for complete hair removal, the concentration of hydroxyproline in the hair removal waste liquid, and whether the wool formed balls. The higher the concentration of hydroxyproline (a characteristic amino acid of collagen) in the hair removal waste liquid, the greater the degree of damage to the sheepskin collagen.

[0045] The test results are shown in Table 1. The protease penetration depth of Example 1 at 60 min of hair removal was significantly higher than that of Comparative Examples 1-4; the sheepskin was completely dehaired at 150 min of hair removal, and the hair removal rate was higher than that of Comparative Examples 1-5 and 7; the time taken for complete hair removal was lower than that of Comparative Examples 1-5 and 7; the concentration of hydroxyproline in the hair removal waste liquid at complete hair removal was lower than that of Comparative Examples 1-7. This shows that compared with the comparative examples, the method for separating sheepskin and wool provided by the present invention can improve the hair removal efficiency of sheepskin while ensuring little damage to the skin collagen by protease, and the obtained wool does not form balls.

[0046] Table 1 Comparison table of hair removal effects

[0047] 。

[0048] Example 2

[0049] The following material dosages are all in terms of the mass percentage (wt%) of goatskin.

[0050] The goatskin was loaded into a rotating drum, water, sodium hydroxide and sodium carbonate were added for deep degreasing until the degreasing rate reached 85%; then the liquid was changed, 400% water was added, the temperature was adjusted to 25 °C, 2% protease preparation (containing animal protease and plant protease) was added, after rotating for 40 min (the protease penetration depth was 1 / 2), the temperature was adjusted to 45 °C, and intermittent rotation was carried out for 80 min. The total hair removal time was 120 min. During this process, a wool filter was used to timely separate and discharge the removed wool to obtain wool and dehaired goatskin.

[0051] After detection, the hair removal rate of this example was 99.8%, the concentration of hydroxyproline in the waste liquid was 22.1 mg / L, and the wool did not form balls.

[0052] Example 3

[0053] The following material dosages are all in terms of the mass percentage (wt%) of sheepskin.

[0054] Put the sheepskin into a drum, add water, surfactant and sodium hydroxide for deep degreasing until the degreasing rate reaches 95%; then change the liquid, add 600% water, adjust the temperature to 15°C, add 0.5% protease preparation (including microbial protease, animal protease and plant protease), rotate for 90 min (the penetration depth of protease is 7 / 12), then adjust the temperature to 40°C, rotate intermittently for 150 min, and the total hair removal time is 240 min. During this process, use a hair filter to timely separate and discharge the removed wool to obtain wool and hair-removed sheepskin.

[0055] After detection, the hair removal rate of this example is 99.1%, the concentration of hydroxyproline in the waste liquid is 26.9 mg / L, and the wool does not form balls.

[0056] Example 4

[0057] The following material dosages are all calculated based on the mass percentage (wt%) of goatskin.

[0058] Put the goatskin into a drum, add water and surfactant for deep degreasing until the degreasing rate reaches 80%; then change the liquid, add 500% water, adjust the temperature to 20°C, add 1.5% protease preparation (including microbial protease), rotate for 60 min (the penetration depth of protease is 2 / 3), then adjust the temperature to 35°C, rotate for 120 min, and the total hair removal time is 180 min. During this process, use a hair filter to timely separate and discharge the removed wool to obtain wool and hair-removed goatskin.

[0059] After detection, the hair removal rate of this example is 100%, the concentration of hydroxyproline in the waste liquid is 33.8 mg / L, and the wool does not form balls.

[0060] The above are only the preferred embodiments of the present invention and are not used to limit the present invention. For those skilled in the art, the present invention can have various changes and modifications. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included within the protection scope of the present invention.

Claims

1. A method for separating sheepskin from its fur, characterized in that, During the fur separation process, only water and protease are added to the deeply degreased sheepskin, and enzymatic depilation is carried out at 15-25°C. After the protease penetrates into the skin to a depth reaching 1 / 2-2 / 3 of the thickness of the sheepskin, the temperature is raised to 35-45°C and depilation continues until depilation is completed. During the whole process, the removed wool is discharged in a timely manner; wherein, the degreasing rate of the deep degreasing is ≥80%.

2. The method for separating sheepskin and wool as claimed in claim 1, characterized in that The protease is selected from any one or more of microbial protease, animal protease and plant protease.

3. The method for separating sheepskin from wool according to claim 1, characterized in that Any one or more of surfactants, sodium carbonate and sodium hydroxide are used to deeply degrease the sheepskin.

4. Wool and sheepskin obtained by using the sheepskin fur separation method according to any one of claims 1-3.