Leather processing technology and device using softening enzyme treatment

Abstract

The present invention provides a leather processing process using softening enzyme treatment, comprising: rinsing animal hides after soaking, dehairing, liming, and splitting; softening the animal hides by adding 70% of the hide weight of water and 0.8% of an ammonium-free deliming agent, and adjusting the temperature to 35°C; then adding a softening solution and softening the animal hides for 70 minutes; the pH value of the softening solution is 8.0; the softening solution comprises 40% of the hide weight of water, 0.12% of a surfactant, and 0.6% of a softening enzyme preparation; and after softening, performing pickling and tanning steps. The present invention has the advantages of using an immobilized enzyme instead of a free enzyme in the leather softening step. The immobilized enzyme has the characteristic of slow release, and compared with a free softening enzyme preparation, the immobilized enzyme can be released slowly, thereby preventing the softening enzyme from being too strong and damaging the animal hide; and after softening, the immobilized enzyme can be separated from other chemical components, which facilitates repeated use of the immobilized enzyme and saves processing costs.

Description

Technical field

[0001] The invention relates to the field of leather processing, and in particular to a leather processing technology and a device thereof using softening enzyme treatment. [Background Technology]

[0002] my country is a major leather processing country in the world, and its processing and export volumes have long ranked first in the world. Therefore, the leather industry has become a light industry with rapid technological progress and development in the national economy, and is closely related to the people's living standards and quality of life.

[0003] The traditional leathermaking process includes soaking, unhairing, liming, deliming, bating, pickling, and tanning. Enzymes are often used in these processes to accelerate unhairing and softening. However, the leathermaking process places high demands on the use of enzymes. Improper use of enzymes in the unhairing step can cause varying degrees of damage to the leather grain, while improper use of enzymes in the softening step can cause the leather to rot. Therefore, enzyme bating is a key step in the leathermaking process and plays a crucial role in the quality of the finished leather.

[0004] In traditional leather-making processes, enzymatic softening is performed on raw hides using pancreatic enzymes under weak alkaline conditions during the preparatory stage. For example, prior art CN 113430187 A discloses a composite enzyme for leather softening, a preparation method, and an application thereof. The composite enzyme preparation for leather softening mainly comprises microbial enzymes protease and lipase. During the softening process, both enzymes are dissolved in the softening solution in a free form. Although the free composite enzyme preparation improves the softening efficiency in the early stages of the softening step, the early softening speed is too fast and the effect on the leather is too strong to be easily controlled, which may cause the leather to rot directly. Moreover, the softening efficiency in the later stages is still reduced, resulting in no improvement in the overall softening efficiency.

[0005] In view of this, the inventors of this case conducted in-depth research on the above-mentioned issues, which led to the creation of this case. [Summary of the invention]

[0006] The present invention aims to solve the technical problems that the existing enzyme preparations for leather softening have high requirements for use and improper operation conditions may easily cause the leather to rot directly. The invention provides a leather processing process and device using softening enzyme treatment, which can slowly release the softening enzyme preparation and has a simple and controllable softening process.

[0007] The present invention is achieved in that a leather processing process using softening enzyme treatment comprises the following steps:

[0008] (1) Rinse the animal hides after soaking, dehairing, liming and splitting;

[0009] (2) Softening the animal hide: adding 60% to 80% of the hide weight of water and 0.5 to 1.0% of an ammonium-free deliming agent, adjusting the temperature to 30 to 38° C.; then adding a softening liquid to soften the animal hide for 50 to 90 minutes; the pH value of the softening liquid is 7.5 to 8.5; the softening liquid comprises 20 to 50% of the hide weight of water, 0.05 to 0.15% of a surfactant, and 0.2 to 0.8% of a softening enzyme preparation;

[0010] (3) After softening, pickling and tanning processes are carried out.

[0011] Furthermore, in step (2), the softening treatment time is 70 minutes.

[0012] Furthermore, in step (2), the softening liquid comprises 40% by weight of water, 0.12% of a surfactant, and 0.6% of a softening enzyme preparation.

[0013] Furthermore, in step (2), the softening enzyme preparation is an immobilized enzyme.

[0014] Furthermore, the immobilized enzyme is chitosan-immobilized pancreatic enzyme.

[0015] Furthermore, the preparation process of the chitosan-immobilized pancreatin is as follows:

[0016] Step 1: Add 1-2 g of chitosan to 100-200 mL of a 1-2% lactic acid solution, and stir magnetically for 1-2 hours to obtain a chitosan-lactic acid solution;

[0017] Step 2: Add the chitosan-lactic acid solution dropwise to 200-300 mL of 10-20 mg / L sodium phosphate pentaphosphate solution using a syringe and solidify for 2-3 hours, then wash with deionized water until neutral to obtain white chitosan particles with uniform particle size and regular shape;

[0018] Step 3: Soak 1-2g of chitosan particles in 100-200mL of pancreatic enzyme solution, then add 0.1-0.2g of polyethylene glycol, and immobilize the reaction in a refrigerator at 4-8°C for 12-20h; then wash with deionized water three times to remove unimmobilized pancreatic enzyme to obtain granular chitosan-immobilized pancreatic enzyme; the pH value of the pancreatic enzyme solution ranges from 7.0 to 8.0; the dosage ratio of the chitosan particles to pancreatic enzyme is 1 (g): 100-200 (IU).

[0019] Furthermore, in step three, the chitosan particles and pancreatic enzyme are used in a ratio of 1 (g):150 (IU).

[0020] Furthermore, in step three, the immobilization reaction is performed for 15 hours.

[0021] On the other hand, a processing device applied to the leather processing process using softening enzyme treatment includes a fur separation mechanism for dehairing animal skins and a softening mechanism for softening animal skins.

[0022] Furthermore, the softening device includes a softening chamber, the bottom of which is semicircular; a flipping mechanism is provided in the softening chamber, a feed port is formed on the top of the softening chamber, a discharge port and a liquid return port are formed on the side wall of the softening chamber, and the discharge port is located above the liquid return port; a heating mechanism is provided at the bottom end of the softening chamber; a tilted discharge pipe is fixedly installed at the discharge port, a liquid return pipe is fixedly connected to the lower middle part of the discharge pipe, one end of the liquid return pipe is connected to the discharge pipe, and the other end of the liquid return pipe is connected to the softening chamber through the liquid return port, and a filter is installed at the connection between the liquid return pipe and the discharge pipe.

[0023] The advantages of the present invention are:

[0024] 1. The present invention uses immobilized enzymes instead of free enzymes in the leather softening step. Immobilized enzymes have the characteristic of slow release. Compared with traditional free-state softening enzyme preparations, immobilized enzymes can be released slowly, avoiding rapid action and damage to animal hides. Immobilized enzymes not only maintain high catalytic efficiency and specificity and mildness, but also improve the enzyme's thermal and chemical stability. Furthermore, after use, the softening liquid made with immobilized enzymes can be separated from other chemical components using simple methods such as centrifugation and filtration, facilitating repeated use of the immobilized enzymes and product purification, thereby saving processing costs.

[0025] 2. The immobilized enzyme of the present invention adopts chitosan immobilized pancreatin. Chitosan immobilized pancreatin not only has the advantage of good thermal stability with chitosan as a carrier, but also has a long retention time of enzyme activity under high temperature conditions, and the chitosan immobilized pancreatin preparation process is simple, the reaction conditions are mild, and it is easy to operate, which is beneficial to production. Equal amounts of chitosan immobilized pancreatin and conventional enzyme preparations are respectively incubated for 2h at the same temperature. Finally, it is found that the activity loss of chitosan immobilized pancreatin is small. It can be seen that chitosan immobilized pancreatin has good thermal stability. Therefore, the present invention uses chitosan immobilized pancreatin as a softening enzyme preparation to maintain softening efficiency without damaging animal skin.

[0026] 3. In the preparation process of chitosan-immobilized pancreatic enzyme of the present invention, polyethylene glycol is added during the process of combining chitosan particles as a carrier with pancreatic enzyme. Polyethylene glycol is stable in nature and not only does not react with chitosan particles and pancreatic enzyme solution, but also can greatly improve the adsorption rate of chitosan to pancreatic enzyme.

[0027] 4. The present invention drips the chitosan-lactic acid solution into the alkaline pentasodium phosphate solution. The pentasodium phosphate has a solidifying effect here, which facilitates the chitosan to form particles. Moreover, after the softening liquid is prepared later, the pentasodium phosphate is dispersed in the solution to play the role of pre-tanning and shortening the softening time, which can protect the leather from damage in the later stage.

[0028] 5. The leather processing device of the present invention can soften animal skins. The softening mechanism can not only soften animal skins efficiently, but also recover the immobilized enzyme in the softening liquid at a later stage, thereby effectively saving production costs.

Brief Description of the Drawings

[0029] The present invention will be further described below with reference to the accompanying drawings and embodiments.

[0030] Figure 1 It is a three-dimensional diagram of the softening mechanism in the third embodiment of the present invention.

[0031] Figure 2 It is a cross-sectional view of the softening mechanism in the third embodiment of the present invention.

[0032] Figure 3 It is a structural diagram of the fur separation mechanism in embodiment three of the present invention.

[0033] Figure 4 It is a three-dimensional diagram of the gathering component in the third embodiment of the present invention.

[0034] Fur separation mechanism 100, processing mechanism 1, frame 11, support base 12, frame cover 13, fur output port 14, first liquid inlet 15, first liquid outlet 16, liquid supply mechanism 2, second liquid inlet 21, second liquid outlet 22, liquid pump 23, solution recovery mechanism 3, hair collection mechanism 4, roller 41, rotating cylinder 5, first driving mechanism 51, movable rod 52, filtering assembly 6, flow disturbing mechanism 7, second driving mechanism 71, stirring blade 72, hair cleaning mechanism 8, gathering assembly 81, push plate 811, first curved portion 812, second curved portion 813, fur gathering chamber 814, fur gathering port 815, liquid discharge port 816, third driving mechanism 82;

[0035] Softening mechanism 200, softening chamber 9, feed port 91, discharge port 92, liquid return port 93, heating mechanism 94, heating plate 941, heater 942, flipping mechanism 95, flipping motor 951, flipping shaft 952, flipping blades 953, discharge pipe 96, liquid return pipe 97, filter screen 98, controller 99. [Specific implementation method]

[0036] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. Therefore, the following detailed description of the embodiments of the present invention provided in the drawings is not intended to limit the scope of the invention for which protection is sought, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention.

[0037] Example 1

[0038] This embodiment provides a leather processing process using softening enzyme treatment, which specifically includes the following steps:

[0039] (1) Rinse the animal hides after soaking, dehairing, liming and splitting;

[0040] (2) Softening the animal hide: adding 60% to 80% of the hide weight of water and 0.5 to 1.0% of an ammonium-free deliming agent, adjusting the temperature to 30 to 38° C.; then adding a softening liquid to soften the animal hide for 50 to 90 minutes; the pH value of the softening liquid is 7.5 to 8.5; the softening liquid comprises 20 to 50% of the hide weight of water, 0.05 to 0.15% of a surfactant, and 0.2 to 0.8% of a softening enzyme preparation;

[0041] (3) After softening, pickling and tanning processes are carried out.

[0042] In this embodiment, in step (2), the softening treatment time is 70 minutes to improve the softening efficiency. If the softening treatment time is too short, the animal skin will not be softened thoroughly; if the softening treatment time is too long, the leather may be damaged or even rot.

[0043] In this embodiment, in step (2), in order to improve the softening effect, the surfactant is fatty alcohol polyoxyethylene ether.

[0044] In this embodiment, in step (2), the softening liquid includes 40% by weight of water, 0.12% of a surfactant, and 0.6% of a softening enzyme preparation.

[0045] In this embodiment, in step (2), the softening enzyme preparation is an immobilized enzyme. The immobilized enzyme has the characteristic of slow release. Compared with the traditional softening enzyme preparation in a free state, the present invention uses an immobilized enzyme instead of a free enzyme in the leather softening step. The immobilized enzyme in the softening solution can be slowly released, thereby avoiding the softening enzyme from reacting too quickly and damaging the animal skin. The immobilized enzyme not only has the characteristics of maintaining efficient enzyme catalysis and specificity and mildness, but also improves the thermal stability and chemical stability of the enzyme; and after use, the softening solution made from the immobilized enzyme can be separated from other chemical components by simple methods such as centrifugation and filtration, which is conducive to the repeated use of the immobilized enzyme and the purification of the product, thereby saving processing costs.

[0046] In the present embodiment, described immobilized enzyme is chitosan immobilized pancreatin.Chitosan immobilized pancreatin not only has the good advantage of heat stability with chitosan as carrier, and the maintenance time of enzyme activity is long under high temperature state, and chitosan immobilized pancreatin preparation technology is simple, reaction conditions are gentle, easy to operate, is beneficial to production.Equivalent chitosan immobilized pancreatin and conventional enzyme preparation are incubated respectively for 2h as at the same temperature, finally find that the activity loss amount of chitosan immobilized pancreatin is little, and visible chitosan immobilized pancreatin has good heat stability.So the present invention uses chitosan immobilized pancreatin as softening enzyme preparation can keep softening efficiency and not damage animal skin simultaneously.

[0047] The following further illustrates the beneficial effects of the leather processing technology using this embodiment through several experimental and comparative groups. Specifically, the constant parameters were 10 kg of animal hides, 70% water by weight, 0.8% ammonium-free deliming agent, a temperature of 35°C, and a softening solution with a pH of 8.0. Each experimental and comparative group had different softening solution parameters and different softening times. The experiments were conducted and the damage to the animal hides was examined after softening was completed.

[0048] Experimental Group 1

[0049] The leather processing technology of softening enzyme treatment in this experimental group is as follows:

[0050] First, 10 kg of animal skins are soaked, dehaired, limed and peeled, and then rinsed and softened: 70% of the skin weight of water and 0.8% of an ammonium-free deliming agent are added, and the temperature is adjusted to 35°C; then a softening liquid is added to soften the animal skin for 50 minutes; the pH value of the softening liquid is 8.0; the softening liquid includes 20% of the skin weight of water, 0.05% of a surfactant, and 0.2% of a softening enzyme preparation; the damage of the animal skin is observed; and after the softening is completed, pickling and tanning processes are carried out.

[0051] Experimental Group 2

[0052] The leather processing technology of softening enzyme treatment in this experimental group is as follows:

[0053] First, 10 kg of animal skins are soaked, dehaired, limed and peeled, and then rinsed and softened: 70% of the skin weight of water and 0.8% of an ammonium-free deliming agent are added, and the temperature is adjusted to 35°C; then a softening liquid is added to soften the animal skin for 60 minutes; the pH value of the softening liquid is 8.0; the softening liquid includes 30% of the skin weight of water, 0.10% of a surfactant, and 0.4% of a softening enzyme preparation; the damage of the animal skin is observed; and after softening, pickling and tanning processes are carried out.

[0054] Experimental Group 3

[0055] First, 10 kg of animal skins are soaked, dehaired, limed and peeled, and then rinsed and softened: 70% of the skin weight of water and 0.8% of an ammonium-free deliming agent are added, and the temperature is adjusted to 35°C; then a softening liquid is added to soften the animal skin for 70 minutes; the pH value of the softening liquid is 8.0; the softening liquid includes 40% of the skin weight of water, 0.12% of a surfactant, and 0.6% of a softening enzyme preparation; the damage of the animal skin is observed; and after the softening is completed, the pickling and tanning processes are carried out.

[0056] Experimental group 4

[0057] First, 10 kg of animal skins are soaked, dehaired, limed and peeled, and then rinsed and softened: 70% of the skin weight of water and 0.8% of an ammonium-free deliming agent are added, and the temperature is adjusted to 35°C; then a softening liquid is added to soften the animal skin for 90 minutes; the pH value of the softening liquid is 8.0; the softening liquid includes 50% of the skin weight of water, 0.14% of a surfactant, and 0.7% of a softening enzyme preparation; the damage of the animal skin is observed; and after softening, pickling and tanning processes are carried out.

[0058] Experimental Group 5

[0059] First, 10 kg of animal skins are soaked, dehaired, limed and peeled, and then rinsed and softened: 70% of the skin weight of water and 0.8% of an ammonium-free deliming agent are added, and the temperature is adjusted to 35°C; then a softening liquid is added to soften the animal skin for 90 minutes; the pH value of the softening liquid is 8.0; the softening liquid includes 50% of the skin weight of water, 0.15% of a surfactant, and 0.8% of a softening enzyme preparation; the damage of the animal skin is observed; and after the softening is completed, pickling and tanning processes are carried out.

[0060] Comparison group 1

[0061] First, 10 kg of animal skins are soaked, dehaired, limed and peeled, and then rinsed and softened: 70% of the skin weight of water and 0.8% of an ammonium-free deliming agent are added, and the temperature is adjusted to 35°C; then a softening liquid is added to soften the animal skin for 70 minutes; the pH value of the softening liquid is 8.0; the softening liquid includes 50% of the skin weight of water, 0.12% of a surfactant, and 0.9% of a softening enzyme preparation; the damage of the animal skin is observed; and after softening, pickling and tanning processes are carried out.

[0062] Comparison group 2

[0063] First, 10 kg of animal skins are soaked, dehaired, limed and peeled, and then rinsed and softened: 70% of the skin weight of water and 0.8% of an ammonium-free deliming agent are added, and the temperature is adjusted to 35°C; then a softening liquid is added to soften the animal skin for 90 minutes; the pH value of the softening liquid is 8.0; the softening liquid includes 50% of the skin weight of water, 0.12% of a surfactant, and 0.9% of a softening enzyme preparation; the damage of the animal skin is observed; and after softening, pickling and tanning processes are carried out.

[0064] Comparison group 3

[0065] First, 10 kg of animal skins are soaked, dehaired, limed and peeled, and then rinsed and softened: 70% of the skin weight of water and 0.8% of an ammonium-free deliming agent are added, and the temperature is adjusted to 35°C; then a softening liquid is added to soften the animal skin for 70 minutes; the pH value of the softening liquid is 8.0; the softening liquid includes 40% of the skin weight of water, 0.12% of a surfactant, and 1.0% of a softening enzyme preparation; the damage of the animal skin is observed; and after softening, pickling and tanning processes are carried out.

[0066] Comparison group 4

[0067] First, 10 kg of animal skins are soaked, dehaired, limed and peeled, and then rinsed and softened: 70% of the skin weight of water and 0.8% of an ammonium-free deliming agent are added, and the temperature is adjusted to 35°C; then a softening liquid is added to soften the animal skin for 70 minutes; the pH value of the softening liquid is 8.0; the softening liquid includes 40% of the skin weight of water, 0.12% of a surfactant, and 1.2% of a softening enzyme preparation; the damage of the animal skin is observed; and after softening, pickling and tanning processes are carried out.

[0068] Comparison group 5

[0069] First, 10 kg of animal skins are soaked, dehaired, limed and peeled, and then rinsed and softened: 70% of the skin weight of water and 0.8% of an ammonium-free deliming agent are added, and the temperature is adjusted to 35°C; then a softening liquid is added to soften the animal skin for 70 minutes; the pH value of the softening liquid is 8.0; the softening liquid includes 40% of the skin weight of water, 0.12% of a surfactant, and 1.2% of animal trypsin; the damage of the animal skin is observed; and after softening, pickling and tanning processes are carried out.

[0070] According to the experimental results of the above five experimental groups and five control groups, the damage to the animal skin was detected as follows:

[0071] Table 1 Relevant data of each experimental group and comparison group

[0072]

[0073]

[0074] As can be seen from Table 1, the five experimental groups used the softening liquid of this embodiment to soften animal skins. After the softening was completed, the animal skins were not damaged. According to the detection results of the five control groups and the five comparison groups, it can be seen that when the softening enzyme preparation exceeds 0.8%, the animal skin will only be slightly damaged; the amount of surfactant used will not cause damage to the leather surface, and its percentage range is the conventional amount, so no excessive testing is done; from the experimental results of experimental group three and comparison group five, it can be seen that under the same conditions, using conventional animal trypsin instead of the chitosan immobilized trypsin of this embodiment, the entire leather is obviously damaged. It can be seen that the present invention uses chitosan immobilized trypsin as a softening enzyme preparation to maintain softening efficiency while not damaging animal skin.

[0075] Example 2

[0076] This embodiment provides a preparation process of chitosan-immobilized pancreatin, and the specific steps are as follows:

[0077] Step 1: Add 1-2 g of chitosan to 100-200 mL of a 1-2% lactic acid solution, and stir magnetically for 1-2 hours to obtain a chitosan-lactic acid solution; add chitosan to the acidic solution to make the chitosan more soluble.

[0078] Step 2: Use a syringe to drip the chitosan-lactic acid solution into 200-300 mL of 10-20 mg / L pentasodium phosphate solution and solidify for 2-3 hours, and then wash with deionized water until neutral to obtain white chitosan particles with uniform particle size and regular shape; drip the chitosan-lactic acid solution into the alkaline liquid pentasodium phosphate solution, where the pentasodium phosphate has a solidifying effect, facilitating the formation of chitosan particles.

[0079] Step 3: Soak 1-2g of chitosan granules in 100-200mL of pancreatic enzyme solution, then add 0.1-0.2g of polyethylene glycol. Immobilize the mixture in a refrigerator at 4-8°C for 12-20 hours. Wash the mixture three times with deionized water to remove any unimmobilized pancreatic enzyme, producing chitosan-immobilized pancreatic enzyme granules. The pancreatic enzyme solution has a pH range of 7.0-8.0. The chitosan granules and pancreatic enzyme are used in a ratio of 1g:100-200IU. Polyethylene glycol is added during the process of binding the chitosan granules to the pancreatic enzyme. Polyethylene glycol is stable and does not react with the chitosan granules or the pancreatic enzyme solution. It also significantly improves the adsorption rate of pancreatic enzymes to chitosan.

[0080] The preparation process of the chitosan-immobilized pancreatic enzyme of this embodiment not only produces chitosan-immobilized pancreatic enzyme with high enzymatic activity, but also has a simple process, convenient operation, and a high conversion rate of the chitosan-immobilized pancreatic enzyme. Furthermore, since the granular chitosan-immobilized pancreatic enzyme of the present invention is a mixture containing pentasodium phosphate, after being prepared into a softening solution, the pentasodium phosphate dispersed in the solution can also serve as a pre-tanning agent and shorten the softening time, thereby protecting the leather grain from damage in the later stage.

[0081] In step 3 of this embodiment, the ratio of the chitosan particles to pancreatic enzyme is 1 (g):150 (IU).

[0082] The following experiment was conducted using 1g of chitosan particles and different amounts (different enzyme activities) of pancreatic enzymes, with the same curing time, to measure the activity of pancreatic enzymes adsorbed by the chitosan particles (i.e., the carrier loading capacity). The following data was obtained:

[0083] Table 2: Effect of the ratio of chitosan particles to pancreatic enzyme on pancreatic enzyme immobilization

[0084] Chitosan (g) 1 1 1 1 1 1 1 Pancreatin (IU) 100 120 140 150 160 180 200 Carrier loading capacity (IU / g) 15.5 25.4 43.1 52.3 49.6 38.9 31.6

[0085] As can be seen from Table 2, the activity of immobilized pancreatic enzyme reaches its maximum when the mass ratio of chitosan to pancreatic enzyme is 1 (g):150 (IU). As the amount of pancreatic enzyme increases, the activity of pancreatic enzyme adsorbed on chitosan (i.e., the carrier loading capacity) first increases and then decreases. When the enzyme dosage increases to 150 IU / g, the carrier loading capacity reaches its maximum value of 52.3 IU / g.

[0086] In step 3 of this example, the optimal immobilization reaction time was 15 hours. Next, 0.1 g of polyethylene glycol was added to a chitosan granule and pancreatic enzyme solution at a dosage ratio of 1 (g):150 (IU). The immobilization reaction was carried out in a 5°C refrigerator for different lengths of time to measure the activity of pancreatic enzyme adsorption by chitosan (i.e., carrier loading capacity). The following data were obtained:

[0087] Table 3: Effect of immobilization time on pancreatic enzyme immobilization

[0088] Immobilization time (h) 12 13 14 15 16 17 20 Carrier loading capacity (IU / g) 41.2 49.1 51.0 54.2 52.3 48.6 45.7

[0089] Table 3 shows that with increasing immobilization reaction time, the activity of pancreatic enzyme adsorbed on chitosan (i.e., carrier loading capacity) initially increases and then decreases, reaching a maximum of 54.2 IU / g after 15 hours. This indicates that under the given conditions, 15 hours is sufficient to complete the immobilization reaction and reach saturation. Extending the reaction time further can lead to structural changes in the pancreatic enzyme under the influence of other substances, resulting in inactivation and a decrease in the specific activity of the immobilized enzyme.

[0090] Example 3

[0091] See also Figures 1 to 4 As shown, this embodiment provides a leather processing device, including a fur separation mechanism 100 for depilating animal skins, and a softening mechanism 200 for softening animal skins.

[0092] In this embodiment, the softening mechanism 200 includes a softening chamber 9, the bottom of which is semicircular; a flipping mechanism 95 is provided in the softening chamber 9, a feed port 91 is formed on the top of the softening chamber 9, a discharge port 92 and a liquid return port 93 are formed on the side wall of the softening chamber 9, and the discharge port 92 is located above the liquid return port 93; a heating mechanism 94 is provided at the bottom end of the softening chamber 9; a tilted discharge pipe 96 is fixedly installed at the discharge port 92, and a liquid return pipe 97 is fixedly connected to the lower middle part of the discharge pipe 96, one end of the liquid return pipe 97 is connected to the discharge pipe 96, and the other end of the liquid return pipe 97 is connected to the softening chamber 9 through the liquid return port 93, and a filter screen 98 is installed at the connection between the liquid return pipe 97 and the discharge pipe 96.

[0093] Working Principle: Animal hides and softening liquid are placed into softening chamber 9 through feed port 91. A turning mechanism 95 slowly turns the hides, while a heating mechanism 94 heats the softening liquid inside softening chamber 9. Under the action of turning mechanism 95, the hides and softening liquid are gradually and evenly mixed, and the softening process is completed. When softening is complete, the hides flow into discharge pipe 96. During the discharge process, any softening liquid remaining on the hides passes through filter screen 98 into return pipe 97 and returns to softening chamber 9, thereby preventing excessive loss of softening liquid.

[0094] In this embodiment, in order to ensure the softening quality, the heating mechanism 94 includes a heating plate 941, and a heater 942 is provided under the heating plate 941. The heater 942 controls the heating plate 941 to heat the softening liquid in the softening chamber 9, and controls the temperature at 30-38°C, preferably 35°C.

[0095] In this embodiment, the flipping mechanism 95 includes a flipping motor 951 fixedly mounted on the outer wall of the softening chamber 9 and a flipping assembly rotatably mounted inside the softening chamber 9. The flipping assembly includes a flipping shaft 952 and a plurality of flipping blades 953 fixedly mounted on the flipping shaft 952. The plurality of flipping blades 953 are distributed in a circular array on the outer surface of the flipping shaft 952.

[0096] In this embodiment, a controller 99 is further included, which is arranged on the outer wall of the softening chamber 9 . The output end of the controller 99 is electrically connected to the heater 942 and the flipping motor 951 .

[0097] In this embodiment, the ratio of the length of the flipping blade 953 to the radius of the semicircle is (0.90-0.95):1, so that after the animal hide enters the softening chamber 9, the flipping shaft 952 can drive the flipping blade 953 to flip the animal hide in a circular motion within the softening liquid. The ratio of the length of the flipping blade 953 to the radius of the semicircle is preferably 0.93:1. The ratio is limited to set the gap between the end of the flipping blade 953 and the inner wall of the softening chamber 9. If the gap is too small, the animal hide is likely to get stuck in the inner wall, causing the flipping mechanism 95 to jam; if the gap is too large, the animal hide may not be flipped and may remain deposited at the bottom of the softening chamber 9.

[0098] In this embodiment, the fur separation mechanism 100 includes a processing mechanism 1 for separating fur from animal skins, a liquid supply mechanism 2 for delivering a depilatory agent to the processing mechanism 1, a solution recovery mechanism 3 for recovering the depilatory agent, and a hair collection mechanism 4 for collecting hair; the output end of the liquid supply mechanism 2 is connected to the input end of the processing mechanism 1, the input end of the hair collection mechanism 4 is located at the output end of the processing mechanism 1, and the input end of the solution recovery mechanism 3 is connected to the output end of the processing mechanism 1. In the processing device 100 of the present invention, a depilatory agent is used to dehair the animal skin in the processing mechanism 1. When the processing mechanism 1 is working, the depilatory agent contacts the animal skin. The depilatory agent contains a depilatory enzyme preparation, which is a granular immobilized enzyme. The granular immobilized enzyme is slowly released to avoid too fast a depilation speed; after depilation is completed, the processing mechanism 1 separates the depilatory agent from the animal skin to recycle the depilatory agent and avoid waste of resources.

[0099] Working principle: Water containing 80-150% of the tare weight and washed animal skin are placed into the processing mechanism 1. The liquid supply mechanism 2 transports the pre-configured dehairing agent to the processing mechanism 1 to dehair the animal skin for 3-6 hours until most of the hair is removed; then an ash-free expander is added for alkaline expansion until dehairing is completed; after dehairing is completed, the solution recovery mechanism 3 recovers the dehairing agent discharged from the processing mechanism 1, and the hair collection mechanism 4 collects the hair discharged from the processing mechanism 1.

[0100] In this embodiment, the processing mechanism 1 includes a frame 11, a support base 12 supporting the frame 11, a frame cover 13 rotatably mounted on the upper end of the frame 11, a rotating cylinder 5 rotatably mounted inside the frame 11, a first drive mechanism 51 driving the rotating cylinder 5, and a filter assembly 6 assembled inside the frame 11 and located below the rotating cylinder 5. The drive shaft of the first drive mechanism 51 passes through the rotating cylinder 5 and connects the rotating cylinder 5 to the frame 11. During operation, the rotating cylinder 5 continuously rotates under the drive of the first drive mechanism 51, so that the animal skin in the cylinder is fully contacted with the depilatory agent.

[0101] In this embodiment, two sets of movable rods 52 are provided within the inner cavity of the rotating cylinder 5, and the animal skin is located between the movable rods 52 and the cylinder wall of the rotating cylinder 5 or between the two sets of movable rods 52. As the rotating cylinder 5 rotates, the animal skin contacts the outer wall of the movable rods 52 within the rotating cylinder 5 due to the flexible mechanical action of the movable rods 52. The movable rods 52 continuously bring the depilatory enzyme preparation into contact with the animal skin to initiate a depilatory reaction.

[0102] In this embodiment, the first driving mechanism 51 is preferably a driving motor.

[0103] In this embodiment, the apparatus further includes a flow disturbance mechanism 7 and a second drive mechanism 71 for rotating the flow disturbance mechanism 7. The flow disturbance mechanism 7 is mounted at the center of the bottom of the frame 11 and below the filter assembly 6. The second drive mechanism 71 is located at the outer bottom of the frame 11. Since the depilatory enzyme preparation is a granular immobilized enzyme, it is easily deposited at the bottom of the inner cavity of the frame 11. By installing the flow disturbance mechanism 7 at the center of the bottom of the frame 11, the depilatory agent at the bottom of the frame 11 is disturbed, thereby continuously pushing the granular immobilized enzyme upward, ensuring more complete and uniform contact between the animal skin and the active ingredients in the depilatory agent, thereby facilitating depilation.

[0104] In this embodiment, in order to further reduce the probability of deposition of the granular immobilized enzyme, the flow disturbance mechanism 7 includes a plurality of stirring blades 72 arranged vertically, and the radius of the stirring blade 72 located at the bottom is larger than the radius of the stirring blade 72 located at the top.

[0105] In this embodiment, the second driving mechanism 71 is preferably a driving motor.

[0106] In this embodiment, the filter assembly 6 is a filter screen 98 having a mesh size of 50-200. The filter screen 98 is detachable and can be replaced adaptively to improve the applicability of the processing device due to the different fineness of different animal furs.

[0107] This embodiment also includes a hair cleaning mechanism 8 positioned above the filter assembly 6. This mechanism includes a gathering assembly 81 and a third drive mechanism 82 that drives the gathering assembly 81 to push the fur toward the fur outlet 14. Both sides of the gathering assembly 81 are in contact with the inner wall of the frame 11 to prevent the fur from spilling out. When hair removal is complete, the depilatory reagent and fur within the frame 11 remain stationary, depositing above the filter 98. The third drive mechanism 82 then drives the gathering assembly 81 along the surface of the filter 98, pushing the fur toward the fur outlet 14. The gathering component 81 can not only squeeze out the depilatory agent between the hairs, but also slowly gather the hairs, and finally squeeze all the hairs to be limited at the fur outlet 14, so as to prevent the depilatory agent from flowing downward and the hairs from being scattered again when the depilatory agent is recovered. When the depilatory agent is recovered, the fur outlet 14 is opened, and the third driving mechanism 82 pushes the gathering component 81 out of the frame 11, so that all the hairs fall into the hair collection mechanism 4.

[0108] In this embodiment, the gathering component 81 includes a push plate 811 with an inclined angle, a first bent portion 812 and a second bent portion 813 for gathering fur, the bottom surface of the push plate 811 is tightly fitted with the filter net 98, the upper end of the push plate 811 is connected to one end of the first bent portion 812, and the other end of the first bent portion 812 is connected to one end of the second bent portion 813, the push plate 811, the first bent portion 812 and the second bent portion 813 are surrounded by a fur gathering cavity 814, and a fur gathering mouth 815 is formed between one end of the push plate 811 and the other end of the second bent portion 813; the second bent portion 813 includes a first end connected to the first bent portion 812, and a second end forming the fur gathering mouth 815 with the push plate 811, and the second bent portion 813 is inclined downward from the first end to the second end. By setting the second curved portion 813 to be inclined downward from the first end to the second end, when the gathering component 81 is pushed, on the one hand, the fur and the depilatory agent slowly enter the fur gathering chamber 814 from the fur gathering opening 815, and on the other hand, the depilatory agent flows upward along the upper surface of the second curved portion 813, which can reduce the pushing resistance. At the same time, under the action of water pressure, the second curved portion 813 slowly bends and the fur gathering opening 815 slowly becomes smaller, preventing the fur from running out when the fur gathering chamber 814 is disturbed and surging. By setting the push plate 811 to have an inclined angle, the fur enters the fur gathering chamber 814 along the inclined surface of the push plate 811 during the pushing process of the push plate 811, thereby improving the gathering efficiency of the fur.

[0109] In this embodiment, the second curved portion 813 is made of an elastic material. By making the second curved portion 813 of an elastic material, when the gathering assembly 81 is pushed, the second curved portion 813 can bend downward under the action of water pressure, causing the fur gathering opening 815 to gradually become smaller, thereby preventing the fur from escaping when the fur gathering chamber 814 is disturbed and turbulent.

[0110] In this embodiment, a plurality of drainage ports 816 are formed through the first curved portion 812. The plurality of drainage ports 816 allow the hair removal agent to be discharged from the drainage ports 816 when the gathering assembly 81 is pushed, thereby preventing the hair gathering chamber 814 from being insufficient to accommodate the hair and hair removal agent. Furthermore, the probability of hair violently surging and escaping from the hair gathering chamber 814 is reduced, thereby further improving the hair gathering efficiency.

[0111] In this embodiment, in order to allow the depilatory agent to be discharged smoothly from the drainage ports 816 , a plurality of drainage ports 816 are distributed in a matrix on the first curved portion 812 .

[0112] In this embodiment, the third driving mechanism 82 is a driving cylinder.

[0113] In this embodiment, a roller 41 is provided at the bottom end of the hair collecting mechanism 4 to facilitate the transfer of the collected hair.

[0114] In this embodiment, a first liquid inlet 15 is formed on the upper side of the frame 11, and a first liquid outlet 16 is formed on the bottom of the frame 11; a second liquid outlet 22 is formed on one side of the liquid supply mechanism 2, and a second liquid inlet 21 is provided on the top of the liquid supply mechanism 2; the frame 11 is connected to the solution recovery mechanism 3 through the first liquid inlet 15.

[0115] In this embodiment, a liquid pump 23 is further provided between the processing mechanism 1 and the liquid supply mechanism 2 .

[0116] The foregoing description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Those skilled in the art will readily appreciate that various modifications and variations are possible. Any modifications, equivalent substitutions, or improvements made within the spirit and principles of the present invention are intended to be within the scope of protection of the present invention.

Claims

1. A leather processing process using softening enzyme treatment, characterized in that: The process includes the following steps: (1) Rinse the animal hides after soaking, dehairing, liming and splitting; (2) Softening the animal skin: adding 60%-80% of the weight of the skin and 0.5-1.0% of an ammonium-free deliming agent, and adjusting the temperature to 30-38°C; then adding a softening liquid to soften the animal skin for 50-90 minutes; the pH value of the softening liquid is 7.5-8.5; the softening liquid comprises 20-50% of the weight of the skin, 0.05-0.15% of a surfactant, and 0.2-0.8% of a softening enzyme preparation; the softening enzyme preparation is chitosan-immobilized pancreatic enzyme; the preparation process of the chitosan-immobilized pancreatic enzyme is as follows: Step 1: Add 1-2 g of chitosan to 100-200 mL of a 1-2% lactic acid solution, and stir magnetically for 1-2 hours to prepare a chitosan-lactic acid solution; Step 2: Add the chitosan-lactic acid solution dropwise to 200-300 mL of 10-20 mg / L sodium phosphate pentaphosphate solution using a syringe and solidify for 2-3 hours, then wash with deionized water until neutral to obtain white chitosan particles with uniform particle size and regular shape; Step 3: Soak 1-2g of chitosan particles in 100-200mL of pancreatic enzyme solution, then add 0.1-0.2g of polyethylene glycol, and immobilize the mixture in a refrigerator at 4-8°C for 12-20 hours. The mixture is then washed three times with deionized water to remove unimmobilized pancreatic enzyme, thereby obtaining granular chitosan-immobilized pancreatic enzyme. The pH of the pancreatic enzyme solution is in the range of 7.0-8.

0. The ratio of chitosan particles to pancreatic enzyme is 1 (g): 100-200 (IU). (3) After softening, pickling and tanning processes are carried out.

2. The leather processing process using softening enzyme treatment as claimed in claim 1, characterized in that: In step (2), the softening treatment time is 70 minutes.

3. The leather processing process using softening enzyme treatment as claimed in claim 1, characterized in that: In step (2), the softening liquid includes 40% by weight of water, 0.12% by weight of a surfactant, and 0.6% by weight of a softening enzyme preparation.

4. The leather processing process using softening enzyme treatment as claimed in claim 1, characterized in that: In step three, the ratio of chitosan particles to pancreatic enzyme is 1 (g):150 (IU).

5. The leather processing process using softening enzyme treatment as claimed in claim 4, characterized in that: In step 3, the immobilization reaction was performed for 15 h.

Images