Method for deacidifying Tan sheep fur double-face leather

Abstract

The invention discloses a method for deacidifying Tan sheep fur double-face leather, and particularly relates to the technical field of fur processing, which comprises the following steps: S1, pretreatment before deacidification; s2, washing with water; s3, neutralizing with a neutralizing solution; s4, fat liquoring is carried out; and S5, performing subsequent treatment. According to the method for deacidifying the Tan sheep fur double-face leather, residual chemicals and scraps can be efficiently removed through multi-stage countercurrent water washing, in the neutralization step of the neutralization liquid, the temperature, the chemical proportion and the stirring speed are accurately controlled, bromocresol green detection is combined, it is ensured that the neutralization reaction is complete, the deacidification effect is remarkable, and the deacidification efficiency is high and thorough; through the fat liquoring step, the double-face leather fully absorbs a fat liquoring agent and recovers softness and glossiness, meanwhile, through pretreatment and optimized operation of all links, damage to double-face leather fibers is avoided, the quality of the double-face leather is guaranteed, the quality of the double-face leather is remarkably improved, through biological enzyme softening treatment, use of chemical agents is reduced, environmental pollution is reduced, and the method meets the environmental protection requirement; the environment-friendly benefit is outstanding.

Description

Technical Field

[0001] The invention relates to the technical field of fur processing, in particular to a method for deacidification of Tan sheep fur leather. Background Art

[0002] In the field of fur processing technology, the deacidification treatment of Tan sheepskin fur leather is a key process link. At present, the traditional Tan sheepskin fur leather deacidification method has many shortcomings. For example, the pretreatment step before deacidification is not perfect, and it is difficult to completely remove dirt, blood stains and grease impurities on the leather, resulting in poor subsequent deacidification treatment effect; during the water washing process, the removal efficiency of residual agents is low, and there is a lack of effective pH value control means; in the neutralization step of the neutralization liquid, the stirring method is relatively single and cannot be dynamically adjusted according to the state of the leather, which easily causes uneven agent concentration and affects the completion of the neutralization reaction; during the greasing process, the penetration effect of the greasing agent is not ideal, and the softness and glossiness of the leather are difficult to restore; in addition, the traditional method uses more chemical agents, which not only increases production costs, but also causes greater pollution to the environment. These problems need to be solved urgently to achieve efficient, environmentally friendly and standardized deacidification technology for Tan sheepskin fur leather. Summary of the Invention

[0003] The main purpose of the present invention is to provide a method for deacidification of Tan sheepskin fur leather, which can effectively solve the problems of incomplete pretreatment, low water washing efficiency and uneven neutralization.

[0004] To achieve the above object, the technical solution adopted by the present invention is:

[0005] A method for deacidifying Tan sheep fur leather comprises the following steps:

[0006] S1. Pretreatment before deacidification: before deacidification, soaking, fleshing and degreasing steps are added to remove dirt, blood stains and grease impurities on the leather, creating better conditions for subsequent deacidification treatment;

[0007] S2. Washing: Prepare the wet-ground Tan sheepskin leather and a sufficiently large washing container, add warm water at 32°C to 38°C, calculate the required amount of water based on a mass ratio of water to wet-ground Tan sheepskin leather of 20 to 40:1, and completely immerse the Tan sheepskin leather in the container. Stir to ensure that the washing liquid is in full contact with the leather. Wash for 50 to 70 minutes, checking the washing effect during the washing process, until no debris from wet grinding remains.

[0008] S3. Neutralization with a neutralizing solution: Fix the washed Tan sheepskin leather and prepare a neutralization container. Add warm water at 35°C to 43°C. Calculate the required amount of neutralizing solution based on a mass ratio of neutralizing solution to fixed Tan sheepskin leather of 20 to 30:1. Prepare a neutralizing solution based on a mass ratio of neutralizing tannin PAK, sodium formate, baking soda, and water of 0.5 to 1:0.5 to 1:0.1 to 0.5:1000. Add the solution to the neutralization container and stir to ensure full contact between the neutralizing solution and the leather. During the neutralization process, regularly check the color of the cut with bromocresol green until the color turns green, indicating that the neutralization reaction is complete.

[0009] S4. Fatliquoring: The neutralized Tan sheepskin leather is placed in a fatliquoring container, and warm water at 55°C to 65°C is added. The mass ratio of fatliquoring liquid to neutralized Tan sheepskin leather is 10 to 20:1. The required amount of fatliquoring liquid is calculated, and the mass ratio of fatliquoring agent CUIROL SL, oil dispersant Densotan A and water is 10 to 50:0.5 to 1:1000. The fatliquoring liquid is prepared and added to the fatliquoring container. The neutralized Tan sheepskin leather is completely immersed in the fatliquoring liquid. The stirring device is turned on for stirring to ensure that the fatliquoring liquid is in full contact with the leather. The fatliquoring is carried out for 3 to 6 hours. During this period, the fatliquoring effect is checked to ensure that the leather fully absorbs the fatliquoring agent and restores the softness and gloss of the leather.

[0010] S5. Subsequent processing: After the greasing is completed, the greasing liquid is discharged, and the Tan sheepskin leather is rinsed with clean water to remove the residual greasing liquid and impurities, and the Tan sheepskin leather is dried in preparation for subsequent finishing and processing.

[0011] Preferably, the stirring speed of the fur processing technology in the S2 water washing step is 50-100 rpm.

[0012] Preferably, the stirring speed in the neutralization step of the neutralization solution S3 is 30 to 60 rpm.

[0013] Preferably, the stirring speed in the fat-adding step S4 is 30 to 80 rpm.

[0014] Preferably, the S2 water washing step may also adopt multi-stage countercurrent water washing to improve the efficiency of removing residual agents, and the pH value is regularly tested after water washing to ensure that it reaches an appropriate value.

[0015] Preferably, a variable frequency stirring device is used in the neutralization step S3 of the neutralizing liquid, the rotation speed and direction are dynamically adjusted according to the state of the leather, and the leather is processed in different areas to ensure that the concentration and time of the agent in each part are consistent.

[0016] Preferably, the neutralization step of the neutralizing solution in S3 may also include a softening treatment step, using enzymes to catalyze the deacidification reaction, thereby reducing the use of chemical agents, lowering environmental pollution and making the Tan sheepskin fur leather softer.

[0017] Compared with the prior art, the present invention has the following beneficial effects:

[0018] 1. The present invention can efficiently remove residual reagents and debris through multi-stage countercurrent water washing. The neutralization step of the neutralization liquid ensures complete neutralization reaction by precisely controlling the temperature, reagent ratio and stirring speed, combined with bromocresol green detection, and has a significant deacidification effect, high deacidification efficiency and thoroughness.

[0019] 2. The present invention enables the leather to fully absorb the fatliquor through the fatliquor step, thereby restoring its softness and glossiness. At the same time, the pretreatment and optimized operation of each link avoid damage to the leather fiber, ensure the quality of the leather, and significantly improve the quality of the leather.

[0020] 3. The present invention reduces the use of chemical agents through biological enzyme softening treatment, reduces environmental pollution, meets environmental protection requirements, and has outstanding environmental benefits.

[0021] 4. The present invention can dynamically adjust parameters such as the stirring speed of each step according to real-time detection results of the thickness, density and fiber strength of the leather. It is suitable for Tan sheepskin leather in different states and has strong process adaptability.

[0022] 5. The method provided by the present invention provides a directly reusable reference template for the deacidification process of Tan sheepskin fur leather, realizes standardized and efficient operation, is conducive to improving production efficiency and product quality stability, and has a high degree of operation standardization. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] Figure 1 It is the overall flow chart of the present invention. DETAILED DESCRIPTION

[0024] In order to make the technical means, creative features, objectives and effects achieved by the present invention easier to understand, the present invention is further described below in conjunction with specific implementation methods.

[0025] like Figure 1 As shown, a method for deacidification of Tan sheep fur leather comprises the following steps:

[0026] S1. Pretreatment before deacidification: Before deacidification, soaking, fleshing and degreasing steps are added to remove dirt, blood stains and grease impurities on the leather, creating better conditions for subsequent deacidification treatment.

[0027] In detail, first soak it in water, use water of appropriate temperature, usually room temperature to 40℃, to avoid damage to leather fibers caused by high temperature, then add an appropriate amount of mild surfactant, such as non-ionic or zwitterionic, to enhance the decontamination ability and protect the natural oil of leather. The soaking time is adjusted according to the thickness and pollution degree of leather, and the soaking time is 1 to 4 hours. During this period, it can be stirred or turned over appropriately to ensure uniform soaking, so as to soften the leather and make impurities such as dirt and blood easier to dissolve and fall off, and at the same time restore the natural humidity of the leather, providing a uniform treatment basis for subsequent steps; secondly, fleshing treatment, use professional fleshing machinery to remove the residual flesh, fat and connective tissue on the inside of the leather, and rinse it with clean water, avoiding damage to the leather during operation. Leather fibers can achieve the purpose of reducing the burden of subsequent degreasing and deacidification steps, while improving the softness and air permeability of the leather; secondly, degreasing treatment, select organic solvent or bio-enzyme degreasing agent to use immersion or spraying method to treat the leather, for example, the organic solvent degreasing temperature is 50-70℃, the bio-enzyme degreasing temperature is 40-50℃, the immersion degreasing time is 3-5 minutes, and the spraying method is 1.5-3 minutes, to avoid damage to the leather fibers or incomplete degreasing caused by excessive temperature or excessive time. After degreasing, rinse thoroughly with clean water to remove residual degreasing agent, avoid high temperature and strong acid and alkali environment, and prevent enzyme inactivation; in addition, during the pretreatment process, environmental protection laws and regulations should be strictly observed, wastewater, waste residue and waste gas should be properly handled, and the safety of operators should be ensured.

[0028] S2. Washing: Prepare the wet-ground Tan sheepskin leather and a large enough washing container, add warm water at 32℃~38℃, calculate the required amount of water based on the mass ratio of water to wet-ground Tan sheepskin leather of 20~40:1, and completely immerse the Tan sheepskin leather in the container, stir to make the washing liquid fully contact with the leather, wash for 50 minutes~70 minutes, check the washing effect during the period, until no debris left after wet grinding.

[0029] In detail, first, the leather needs to be pre-sorted by a vibrating screen to remove large particles of debris >2mm, reduce the washing load, use a wide stirring paddle for stirring in subsequent operations, use heat-resistant and corrosion-resistant plastic or stainless steel washing tanks to make primary tanks, secondary tanks and tertiary tanks, the capacity must meet the leather's full stretch and no accumulation, install a constant temperature heating device such as an electric heating tube or a steam coil, calculate the water volume according to the water: leather ratio of 20 to 40:1, weigh the leather in batches and record the total mass, ensure that the water temperature is stable at 32℃ to 38℃, and configure a temperature sensor to provide real-time feedback to the PLC control system; secondly, multi-stage countercurrent washing, the first-stage countercurrent washing temperature is 38℃, the water: leather mass ratio is 40:1, the stirring speed is 50rpm, and the washing time is 20min, which quickly dissolves soluble debris; the second-stage countercurrent washing temperature is 35℃, the water: leather mass ratio is 30:1, the stirring speed is 70rpm, and the washing time is 20min, which removes tiny particles and chemical residues; the third-stage countercurrent washing temperature is 35℃, the water: leather mass ratio is 30:1, the stirring speed is 70rpm, and the washing time is 20min, which removes tiny particles and chemical residues; The washing temperature is 32°C, the water: leather mass ratio is 20:1, the stirring speed is 100 rpm, the washing time is 10 minutes, and the rinsing is to neutral. The water flow direction is that fresh water flows into the tertiary tank and overflows to the primary tank step by step. The drainage of the primary tank is partially reused in the tertiary tank after sedimentation. The primary tank adopts low-speed (50 rpm) intermittent stirring (stirring for 2 minutes / standing for 3 minutes), and the waste heat of the drainage of the primary tank is used to preheat the fresh water through the plate heat exchanger. The tertiary tank is continuously stirred at high speed (100 rpm) to enhance rinsing. A turbidity meter is installed at the outlet of each tank. When the turbidity is greater than 5 NTU, fresh water is switched to monitor the water quality. In addition, samples are taken every 15 minutes and the pH value of the washing liquid is tested with pH test paper (accuracy ±0.5) or a portable pH meter (accuracy ±0.1). When the pH is less than 6.5, 0.5% sodium bicarbonate solution is slowly added, and the amount added each time does not exceed 0.1% of the volume of the washing liquid. When the pH is greater than 8.5, 5% citric acid solution is injected and adjusted to pH in multiple times. 7.0~8.0. After washing, immerse the leather in pure water (pH 7.0) and rinse for 5 minutes. After taking it out, immediately use pH test paper to test the pH value of the leather to ensure that it meets the standard.

[0030] S3. Neutralization with neutralizing liquid: fix the washed Tan sheepskin leather and prepare a neutralization container, add warm water at 35℃~43℃, calculate the required amount of neutralizing liquid according to the mass ratio of neutralizing liquid to fixed Tan sheepskin leather of 20~30:1, prepare neutralizing liquid according to the mass ratio of neutralizing tannin PAK, sodium formate, baking soda and water of 0.5~1:0.5~1:0.1~0.5:1000, add the neutralizing liquid into the neutralization container and stir to make the neutralizing liquid fully contact with the leather, and check the color of the cut with bromocresol green regularly during the neutralization process until the color turns green, which indicates that the neutralization reaction is complete.

[0031] In detail, a modular stainless steel grid (aperture 5mm) is used to divide the leather into 5 areas according to the area. Each area is hung independently and marked with numbers to avoid overlap. A 316L stainless steel tank body that is acid and alkali resistant is used, and the inner wall is polished (Ra≤0.8μm) to reduce solution residue. Four detachable flexible silicone partitions (thickness 5mm, temperature resistance -20℃~150℃) are set in the tank body and fixed by slots to form 3 to 5 independent areas. The bottom of the partition is 10cm away from the bottom of the tank and the top is higher than The liquid level is 5cm to prevent the solution from flowing horizontally. The surface of the partition is coated with polytetrafluoroethylene to reduce adsorption. The height of the grid is adjusted so that the bottom of the leather is 15cm away from the bottom of the tank. The neutralizing solution is prepared according to the mass ratio of neutralizing tannin PAK, sodium formate, baking soda and water of 0.5-1:0.5-1:0.1-0.5:1000. The neutralizing solution is prepared in different areas according to the ratio of neutralizing solution: leather = 20-30:1, and the total amount is calculated. The neutralizing solution is sequentially immersed from area 1 to area 5, with an interval of 5 minutes between each area to avoid solution concentration. The temperature of the neutralization solution is stabilized at 35℃~43℃ by using a jacketed reactor or a constant temperature water bath. Each area is equipped with an independent temperature sensor with an error of ≤±0.5℃. A double-shaft paddle stirrer (speed 30~60rpm) is used. The speed of each area is independently regulated by PLC. The stirring direction is switched (clockwise→counterclockwise) every 15 minutes to reduce fiber entanglement. Microporous aeration heads (air flow rate 0.3~0.8L / min·kg leather) are added at the bottom of area 1 and area 5 to enhance solution circulation. Ring; Bio-enzyme softening synergistic treatment, using acid protease (activity ≥ 50,000U / g) and lipase (activity ≥ 30,000U / g) compounded at a mass ratio of 1:1. When the neutralization reaction is carried out for 30 minutes, enzyme preparation: leather = 0.05~0.1:1 is added to each area. The enzymatic hydrolysis temperature is synchronously controlled at 38℃~40℃ to degrade residual tannic acid, reduce the hardness of the leather board, decompose grease agglomerates, and improve the softness of the leather. Every 20 minutes, use a sharp blade to cut 0.3cm in the center of the area. 2The sample is added with bromocresol green indicator, which is yellow (pH < 6.0). The neutralization time needs to be extended or baking soda needs to be added. The sample is yellow-green (6.5 > pH ≥ 6.0). The leather is still acidic but close to the target range. No additional baking soda is needed, but the neutralization time needs to be extended by 10 to 15 minutes. Stirring should be maintained (30 to 45 rpm) to allow the pH to slowly rise to the target range. The pH value should be retested every 10 minutes until the pH reaches the appropriate value, which is green (pH 6.5 to 7.5). The reaction is complete and enters the next range, which is blue-green (8.0 ≥ pH > 7.5). This indicates that the leather is alkaline but has not reached the threshold where stirring needs to be stopped immediately. The stirring speed should be reduced to 20 to 30 rpm to reduce the violent contact between the reagent and the leather and avoid further increase in pH. 0.3 to 0.5 L of acetate buffer (pH 5.5 to 6.0) is added per 100 L of neutralization solution and the solution is slowly neutralized to pH 5.5. 7.0~7.5, re-measure the pH value every 5 minutes to ensure that the pH is stable within the target range and is blue (pH>8.0), stop stirring immediately, and neutralize locally with citric acid solution (0.5%). Use a portable pH meter to detect the pH value of the regional solution every 20 minutes, with an error of ≤±0.2. The color of the incision in all areas is green for two consecutive tests, and the pH value is stable at 7.0±0.3. The total neutralization time is controlled at 60~120 minutes, including the enzymatic hydrolysis time. After the neutralization is terminated, perform multi-stage rinsing and deenzyme to remove the surface neutralization solution and the residual enzyme preparation.

[0032] S4. Fatting: Place the neutralized Tan sheepskin leather in a greasing container, add warm water at 55℃~65℃, calculate the required amount of greasing liquid based on the mass ratio of greasing liquid to neutralized Tan sheepskin leather of 10~20:1, prepare greasing liquid according to the mass ratio of cuirol SL, oil dispersant Densotan A and water of 10~50:0.5~1:1000, and add it to the greasing container, completely immerse the neutralized Tan sheepskin leather in the greasing liquid, turn on the stirring device to stir, so that the greasing liquid and leather are in full contact, and greasing for 3~6 hours. During this period, check the greasing effect to ensure that the leather fully absorbs the greasing agent and restores the softness and gloss of the leather.

[0033] Specifically, it adopts 316L stainless steel tank, with polished inner wall (Ra≤0.8μm), and the volume is designed according to 6 to 8 times of the volume of leather (for example, 6 to 8m are needed to process 100kg of leather). 3Container), equipped with a constant temperature jacket with a temperature control accuracy of ±1°C and a low shear stirrer with a speed range of 20-100 rpm. Randomly select 3-5 pieces of neutralized leather for moisture content testing. If the moisture content of the leather is greater than 40% and it feels damp, it needs to be centrifuged and dehydrated to 25%-30%. No water droplets will seep out when squeezed by hand. The fatliquor ratio is calculated based on a fatliquor to leather mass ratio of 10-20:1. The total amount of fatliquor (kg) = leather mass (kg) × (10-20). For example, to process 100 kg of leather, the total amount of fatliquor is 1000-2000 kg. The fatliquor is prepared according to the mass ratio of fatliquor CUIROL SL, oil dispersant Densotan A, and water of 10-50:0.5-1:1000. Pour warm water at 55-65°C into the 316L stainless steel tank, accounting for 80% of the total water volume. Start stirring at 20 rpm and slowly add CUIROL. Stir SL and Densotan A for 30 minutes until they are completely dissolved, add the remaining 20% ​​warm water, adjust the temperature to 60℃±1℃, test the pH value (target 6.5~7.5), if the deviation is >0.3, fine-tune with 0.1mol / L NaOH or HCl, hang the leather vertically on the grid, ensure that it is completely immersed 15cm below the liquid surface, avoid floating or folding, stir at low speed from 0 to 1 hour, the stirring speed is 30rpm, to prevent the leather fibers from entanglement, gradually increase the speed to 80rpm from 1 to 4 hours to promote the penetration of the fatliquor, and reduce the speed to 40rpm from 4 to 6 hours to reduce mechanical damage. At the same time, conduct time node inspections, extract leather samples at 1 hour, observe whether there is an oil film formed in the fiber gap, press the leather surface with filter paper at 3 hours to detect oil seepage (target ≤0.1g / 10cm 2 ), cut the leather fiber after 6 hours, observe the cuticle oil drop coverage under the microscope (the target is ≥80%), if the fat is insufficient (the oil penetration is less than 0.05g / 10cm 2 ), extend the treatment time for 1 hour, and add CUIROL SL at a dosage of 10% of the original formula. If excessive fat addition (oil seepage > 0.2g / 10cm 2 ), reduce the stirring speed to 30 rpm, and add 5% warm water to dilute.

[0034] S5. Subsequent processing: After the greasing is completed, the greasing liquid is discharged, and the Tan sheepskin leather is rinsed with clean water to remove the residual greasing liquid and impurities, and the Tan sheepskin leather is dried in preparation for subsequent finishing and processing.

[0035] Specifically, rinse the fat-liquored Tan sheepskin leather with clean water to remove residual fat-liquor and impurities, then transfer the leather to a centrifuge and run it at 800 rpm for 5 minutes to remove excess fat-liquor on the surface, then spread it on a ventilation rack at a temperature of ≤35°C and a humidity of ≤60%, avoid direct sunlight, and dry it for ≥24 hours.

[0036] It should be noted that in the S2 washing step, thick and dense leather, such as winter leather, has small fiber gaps, and requires high-speed stirring of 60 to 100 rpm to enhance the permeability of the washing liquid and quickly remove wet-grinding debris. If there is a lot of debris on the surface of the leather, for example, if the flesh is not fully removed, high-speed stirring of 70 to 100 rpm is required to accelerate the separation of the debris. If the leather fibers are relatively fragile, such as old sheepskin, low-speed stirring of 30 to 50 rpm is required to avoid fiber breakage.

[0037] In the S3 neutralization step, thick and dense leather needs to be stirred at a medium-high speed of 60 to 80 rpm to ensure that the neutralization liquid penetrates evenly into the deep layer of the leather and balances the pH value. When the fibers are fragile, they need to be stirred at a low speed of 30 to 50 rpm to prevent the local concentration of the neutralization liquid from being too high and causing fiber damage. When there are fewer debris residues, the rotation speed can be appropriately reduced (such as 50 to 70 rpm) to avoid excessive stirring that destroys the balance of the neutralization reaction.

[0038] In the S4 fatliquoring step, thick and dense leather requires medium-high speed stirring at 60-90 rpm to promote uniform penetration of the fatliquoring agent into the gaps between fibers and restore softness. When the fibers are fragile, low-speed stirring at 40-60 rpm is required to prevent the fatliquoring agent from being lost due to high-speed shearing. The residual debris has little effect on fatliquoring, but if there are many impurities, high-speed stirring at 70-100 rpm is required to accelerate removal.

[0039] In addition, the same batch of leather may show different thickness, density and fiber strength at different stages, and the rotation speed needs to be adjusted according to the real-time detection results.

[0040] Example 1: This example uses a method for deacidification of Tan sheep fur leather to treat 50 kg of wet-ground Tan sheep fur leather. The specific operations are as follows:

[0041] S1 is a pretreatment step before deacidification. 50 kg of wet-ground Tan sheepskin leather is immersed in 35°C warm water, a small amount of non-ionic surfactant (0.5 g / L) is added, and stirred for 30 minutes to remove surface dirt. The remaining meat scraps are removed with a fleshing machine to ensure that the thickness of the leather is uniform. A degreasing solution is then prepared and stirred at 38°C for 10 minutes to remove grease.

[0042] S2 washing step, according to the mass ratio of water to wet-grinded Tan sheepskin fur leather is 40:1, the required water volume = 50kg×40=000kg; the Tan sheepskin fur leather is completely immersed in 35℃ warm water, and three-stage countercurrent washing is adopted, with the water temperature decreasing at each stage (38℃→35℃→32℃), and stirring is carried out at a stirring speed of 50-100rpm to improve the efficiency of residual agent removal. During this period, the washing effect is checked every 15 minutes to confirm that no debris remains. The pH value after washing is detected to be 7.2, which meets the neutral requirement.

[0043] S3. Neutralization step of neutralization liquid: prepare neutralizing tannin PAK: sodium formate: baking soda: water = 0.8:0.8:0.8:1000, with a mass ratio of neutralizing liquid to leather of 25:1. The required amount of neutralizing liquid = 50kg×25 = 1250kg. Fix the leather in different areas for treatment. Add 38°C warm water and the prepared neutralizing liquid. Stir at 45rpm. According to the dynamic state of the leather, adjust the speed to 30-60rpm using a variable frequency stirring device to ensure consistency of agent concentration and time. Check the color of the incision with bromocresol green every 30 minutes. After 4 hours, the color turns green and the neutralization is completed. In addition, biological enzymes (0.5g / L) can be introduced to catalyze the deacidification reaction to reduce the use of chemical agents. The leather will be softer after 2 hours of treatment.

[0044] S4, greasing step, prepare according to the greasing agent CUIROLSL: oil dispersant Densotan A: water = 30:0.8:1000, the mass ratio of greasing liquid to leather is 15:1, the required amount of greasing liquid = 50kg×15=750kg, add into 60℃ warm water, immerse the leather completely in the greasing liquid, stir at 50rpm for 4 hours, check the oil seepage every 1 hour during this period to ensure that the leather fully absorbs the greasing agent.

[0045] S5. Subsequent treatment: rinse the leather with clean water to remove residual fatliquor and impurities, spread it flat on a ventilation rack at a temperature of 32°C and a humidity of 50%. After drying for 24 hours, the moisture content is reduced to 10%.

[0046] Example 2. Based on Example 1, this example uses the neutralization step of S3 neutralizing liquid to prepare neutralizing tannin PAK: sodium formate: baking soda: water = 0.5:0.5:0.5:1000, and the fatliquor step of S4 to prepare fatliquor CUIROLSL: oil dispersant Densotan A: water = 10:0.5:1000. The other steps remain unchanged, and the Tan sheepskin fur leather is deacidified.

[0047] Example 3. Based on Example 1, this example uses the S3 neutralization liquid neutralization step as the preparation of neutralizing tannin PAK: sodium formate: baking soda: water = 0.6.5:0.6.5:0.6.5:1000, and the S4 fatliquoring step as the preparation of fatliquor CUIROLSL: oil dispersant DensotanA: water = 20:0.6.5:1000. The other steps remain unchanged, and the Tan sheepskin fur leather is deacidified.

[0048] Example 4. Based on Example 1, this example uses the neutralization step of S3 neutralizing liquid to prepare neutralizing tannin PAK: sodium formate: baking soda: water = 0.9:0.9:0.9:1000, and the fatliquor step of S4 to prepare fatliquor CUIROLSL: oil dispersant Densotan A: water = 40:0.9:1000. Other steps remain unchanged, and the Tan sheepskin fur leather is deacidified.

[0049] Example 5. Based on Example 1, this example uses the neutralization step of S3 neutralizing liquid to prepare neutralizing tannin PAK: sodium formate: baking soda: water = 1:1:1:1000, and the fatliquor step of S4 to prepare fatliquor CUIROLSL: oil dispersant Densotan A: water = 50:1:1000. The other steps remain unchanged, and the Tan sheepskin fur leather is deacidified.

[0050] Comparative Example 1: Based on Example 1, in the neutralization step of the present embodiment, the neutralization solution S3 is prepared according to the ratio of neutralizing tannin PAK: baking soda: water = 0.8:0.8:1000, and the other steps remain unchanged to deacidify the Tan sheepskin fur leather.

[0051] Comparative Example 2: Based on Example 1, in the neutralization step of S3 neutralizing solution, sodium formate: baking soda: water = 0.8:0.8:1000 is prepared, and other steps remain unchanged to deacidify the Tan sheep fur leather.

[0052] It can be seen from Examples 1-5 that in the neutralization step of the neutralizing solution S3, the neutralizing solution is prepared by neutralizing tannin PAK, sodium formate, baking soda and water in a mass ratio of 0.5 to 1:0.5 to 1:0.1 to 0.5:1000 for fully reacting with the leather, and the pH value of the test can be made to be appropriate, and the detection target is green pH 6.5 to 7.5. It can be seen from Comparative Examples 1-2 that in the neutralization step of the neutralizing solution S3, the neutralizing solution is prepared by neutralizing tannin PAK, baking soda and water in a mass ratio for fully reacting with the leather, or the neutralizing solution is prepared by the mass ratio of sodium formate, baking soda and water for fully reacting with the leather, and the pH value of the test is not at an appropriate value, and the detection target is yellow pH <6.0, and the purpose of opening the pores of the Tan sheepskin fur and making the leather soft in Examples 1-5 cannot be achieved. The lack of neutralizing tannin PAK or sodium formate ultimately leads to the failure of deacidification of the Tan sheepskin fur.

[0053] In summary, through optimization measures such as multi-stage countercurrent washing, variable frequency stirring, and biological enzyme softening, the deacidification efficiency and leather quality can be significantly improved, so that the deacidification process of Tan sheepskin fur leather can be standardized and efficiently operated, providing a directly reusable reference template for similar processes.

[0054] The basic principles, main features, and advantages of the present invention are shown and described above. Those skilled in the art should understand that the present invention is not limited to the above embodiments. The above embodiments and descriptions are merely illustrative of the principles of the present invention. Various changes and modifications may be made to the present invention without departing from the spirit and scope of the present invention. Such changes and modifications are intended to fall within the scope of the present invention. The scope of protection claimed in the present invention is defined by the appended claims and their equivalents.

Claims

1. A method for deacidification of Tan sheep fur leather, characterized in that: The following steps are involved: S1. Pretreatment before deacidification: before deacidification, soaking, fleshing and degreasing steps are added to remove dirt, blood stains and grease impurities on the leather, creating better conditions for subsequent deacidification treatment; S2. Washing: Prepare the wet-ground Tan sheepskin leather and a sufficiently large washing container, add warm water at 32°C to 38°C, calculate the required amount of water based on a mass ratio of water to wet-ground Tan sheepskin leather of 20 to 40:1, and completely immerse the Tan sheepskin leather in the container. Stir to ensure that the washing liquid is in full contact with the leather. Wash for 50 to 70 minutes, checking the washing effect during the washing process, until no debris from wet grinding remains. S3. Neutralization with a neutralizing solution: Fix the washed Tan sheepskin leather and prepare a neutralization container. Add warm water at 35°C to 43°C. Calculate the required amount of neutralizing solution based on a mass ratio of neutralizing solution to fixed Tan sheepskin leather of 20 to 30:

1. Prepare a neutralizing solution based on a mass ratio of neutralizing tannin PAK, sodium formate, baking soda, and water of 0.5 to 1:0.5 to 1:0.1 to 0.5:1000. Add the solution to the neutralization container and stir to ensure full contact between the neutralizing solution and the leather. During the neutralization process, regularly check the color of the cut with bromocresol green until the color turns green, indicating that the neutralization reaction is complete. S4. Fatliquoring: Place the neutralized Tan sheepskin leather in a fatliquoring container, add warm water at 55°C to 65°C, calculate the required amount of fatliquoring according to the mass ratio of fatliquoring to neutralized Tan sheepskin leather of 10 to 20:1, prepare fatliquoring according to the mass ratio of fatliquoring agent CUIROLSL, grease dispersant Densotan A and water of 10 to 50:0.5 to 1:1000, and add the fatliquoring to the fatliquoring container, completely immerse the neutralized Tan sheepskin leather in the fatliquoring, turn on the stirring device to stir, so that the fatliquoring liquid is in full contact with the leather, and fatliquoring for 3 to 6 hours, during which the fatliquoring effect is checked to ensure that the leather fully absorbs the fatliquoring agent and restores the softness and gloss of the leather; S5. Subsequent processing: After the greasing is completed, the greasing liquid is discharged, and the Tan sheepskin leather is rinsed with clean water to remove the residual greasing liquid and impurities, and the Tan sheepskin leather is dried in preparation for subsequent finishing and processing.

2. The method for deacidification of Tan sheep fur leather according to claim 1, characterized in that: The stirring speed of the fur processing technology in the S2 water washing step is 50-100 rpm.

3. The method for deacidification of Tan sheep fur leather according to claim 1, characterized in that: The stirring speed in the neutralization step of the S3 neutralization solution is 30 to 60 rpm.

4. The method for deacidification of Tan sheep fur leather according to claim 1, characterized in that: The stirring speed in the S4 fat-adding step is 30 to 80 rpm.

5. The method for deacidification of Tan sheep fur leather according to claim 1, characterized in that: The S2 water washing step can also adopt multi-stage countercurrent water washing to improve the efficiency of removing residual reagents. The pH value is regularly tested after water washing to ensure that it reaches the appropriate value.

6. The method for deacidification of Tan sheep fur leather according to claim 1, characterized in that: In the S3 neutralization step, a variable frequency stirring device is used to dynamically adjust the rotation speed and direction according to the state of the leather, and the leather is processed in different areas to ensure that the concentration and time of each part of the agent are consistent.

7. The method for deacidification of Tan sheep fur leather according to claim 1, characterized in that: The neutralization step of the S3 neutralization solution may also include a softening treatment step, using biological enzymes to catalyze the deacidification reaction and reduce the use of chemical agents.

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