A high-utilization eco-friendly leather manufacturing process

Abstract

This invention relates to a high-utilization eco-friendly leather manufacturing process using salted wet cowhide as raw material, comprising the following steps: pre-soaking → fleshing → main soaking → enzymatic hair removal → liming → leveling → splitting → deliming → softening → pre-tanning → pickling → main tanning → settling → chromium-free retanning → neutralization → filling and dyeing → fatliquoring → over-dyeing → squeezing and stretching → drying → rewetting → softening → flattening → finishing → finished leather. The wet dyeing and finishing and dry finishing sections of this application employ simplified processes with low filler and oil usage. Due to reasonable formulation, the cost is low, yet the performance is good, meeting production requirements. The addition of a "leveling" step reduces the amount of raw material processed and facilitates processing. The finishing system is water-based, resulting in low VOC generation. Graphene is introduced into the finishing agent, resulting in low coating weight and good coating effect.

Description

Technical Field

[0001] This invention relates to the field of leather technology, and in particular to a high-utilization eco-friendly leather manufacturing process. Background Technology

[0002] Leather tanning is a process that involves removing hair and non-collagen fiber components from raw hides, loosening the collagen fibers, tanning them into leather, and then subjecting them to a series of chemical (including biochemical) and mechanical treatments, such as wet dyeing and dry finishing. Traditional leather tanning processes use leather chemicals containing sulfur, chromium, and chlorine, which not only result in large volumes of wastewater discharge and complex, difficult-to-treat pollutants, but also negatively impact the ecological performance of the tanning process and leather products. Furthermore, it leads to low resource utilization value of byproducts and waste, thus affecting the utilization rate of raw hide resources.

[0003] Meanwhile, due to the irregular shape of the raw hide, the thickness and collagen fiber weaving tightness vary in different parts, and there are certain differences between individuals. Taking cowhide as an example, the rump is the thickest, and the abdomen is the thinnest, with the rump being about twice the thickness of the abdomen, while the neck and back are in between. The collagen fiber weaving also follows the same pattern, with the rump having the tightest weave and a higher weave angle, the abdomen having a looser weave and a lower weave angle, and the neck and back being in between. Since leather processing is a standardized process, this inevitably leads to some parts being over-processed and others under-processed.

[0004] The leather-making process can be considered as removal (of useless materials), tanning, and addition (of useful materials). During removal, dense areas are difficult to remove, requiring the addition of excessive chemical materials. This can lead to over-removal of thin and loose areas, making them even looser and thinner. In the dyeing and finishing stage, when fillers and fatliquoring agents need to be added again, loose areas require even more chemical materials, which is excessive for dense areas. This results in low absorption rates of chemical materials, wasting the added raw materials and increasing the pollutant content in the wastewater. This leads to excessively high production and wastewater treatment costs, resulting in significant economic losses. Summary of the Invention

[0005] This invention provides a high-utilization eco-friendly leather manufacturing process to solve the technical problems of low utilization rates of raw material resources and chemical raw materials, and low resource utilization value of by-products and waste in existing leather making. It achieves uniformity of the whole hide, requires less chemical addition, is easy to operate, and reduces the trimming process.

[0006] The present invention adopts the following technical solution:

[0007] A high-utilization eco-friendly leather manufacturing process, using salted wet cowhide as raw material, includes the following steps: pre-soaking → fleshing → main soaking → enzymatic hair removal → liming → regularization → splitting → deliming → softening → pre-tanning → pickling → main tanning → settling → chromium-free retanning → neutralization → filling and dyeing → fatliquoring → coloring → squeezing and stretching → drying → rewetting → softening → flattening → finishing → finished leather;

[0008] The above pre-soaking process is as follows: First, put the salted wet cowhide into the drum, add water, control the liquid ratio at 1.5-2.0, rotate at 3 rpm, and keep the temperature at room temperature; second, add 0.1% of the penetrant Desoagen WT-H (Sichuan Desai'er Chemical Industry Co., Ltd.), 0.1% of the bactericide ME (BASF, Germany), 0.2% of the degreasing agent FG-B (Sichuan Dawei Technology Co., Ltd.), and 0.3% of the soda ash, rotate for 10 minutes, stop for 30 minutes, repeat 4-6 times, stop the drum overnight, and the next day, rotate for 30 minutes and drain.

[0009] The above process involves feeding 7-8 hides per minute to remove the subcutaneous membrane from the main parts of the hide, leaving the meat surface whitish, with only a small amount of membrane remaining at the edges and corners, and cleaning the hair surface thoroughly. Also, remove any meat scraps, whiskers, cow tail, ears, and hooves around the hide.

[0010] The above-mentioned main soaking process is as follows: First, the pre-soaked leather is placed into the drum, water is added, the liquid ratio is controlled at 1.8-2.0, the rotation speed is 3 rpm, and the temperature is room temperature; Second, 0.3-0.5% of Desoagen WT-H (Sichuan Desai'er Chemical Industry Co., Ltd.), 0.3-0.5% of Dowelleym SD (Sichuan Dawei Technology Co., Ltd.), 0.1-0.3% of ME (BASF, Germany), 0.1-0.3% of FG-B (Sichuan Dawei Technology Co., Ltd.), and 0.2-0.4% of soda ash are added. The drum is rotated for 10 minutes and stopped for 20 minutes, repeated 4-6 times, then rotated for 10 minutes and stopped for 50 minutes, repeated 6-8 times. The drum is then left to stand overnight. The next day, the drum is rotated for 30 minutes, and the water is drained.

[0011] The above-mentioned enzymatic hair removal process is as follows: First, immerse the soaked bare skin in the drum, control the liquid ratio at 0.8-1.0, the rotation speed at 6-8 rpm, the internal temperature at 26-28℃, and adjust the pH to 9.0-9.5; add 0.5-1.5% hair removal compound enzyme, 0.1-0.5% keratinase K (Xiasheng Biotechnology Development Co., Ltd.), and 0.5-1.0% tourmaline powder (Lingshou County Baifei Mineral Products Processing Plant), and rotate for 60-180 minutes; when the hair removal rate is >90%, control the liquid ratio at 0.2-0.3, the rotation speed at 3-5 rpm, the internal temperature at 23-26℃, add 2.0% quicklime and 0.15-0.2% sodium hydroxide, and rotate for 60-120 minutes;

[0012] The above-mentioned liming process: After hair removal, add water to make the liquid ratio reach 2.0-2.5, and add 0.15-0.2% of dissolved sodium hydroxide while rotating. First rotate for 60 minutes, then rotate for 5 minutes and stop at 55 degrees Celsius. Repeat this process 4-6 times, stop the drum and let it sit overnight. The next day, rotate for 30 minutes and drain the water.

[0013] The above-mentioned standardization involves: trimming off the edges and corners of the raw hide after soaking in ash to form a more regular rectangle; collecting the trimmed scraps and extracting collagen or collagen aggregates;

[0014] The above splitting process is carried out on a splitting machine with a leather supply speed of approximately 7-8 sheets / min. The thickness of the top-grain grey leather is determined according to a grey leather to blue wet leather ratio of approximately 1.0:0.7, which is generally 2.2-2.4mm. The thickness of the entire leather is basically consistent.

[0015] The above deashing process is as follows: First, the cleaned and split limed bare skin is placed into a rotating drum, with the liquid ratio controlled at 2.0-2.2, the rotation speed at 5-6 rpm, and the internal temperature at 28-29℃. 0.3% of deashing agent TM (Sichuan Desail Chemical Industry Co., Ltd.) is added, and the drum is rotated for 15 minutes. Second, 1.2-1.3% of deashing agent TM (Sichuan Desail Chemical Industry Co., Ltd.) and 0.15% sodium metabisulfite are added, and the drum is rotated for 20 minutes. At the end of the deashing process, the pH of the bath solution is 8.8-9.0, and the temperature is 28-29℃. The bare skin is basically free of swelling, and the grain surface is clean and fine. When the buttock incision is checked with phenolphthalein, it appears purplish-red and is fully transparent or leaves a 1 / 2 line in the center.

[0016] The softening process is as follows: First, the deashed bare hides are placed into a rotating drum, with the liquid ratio controlled at 1.0-1.2, the rotation speed at 5-6 rpm, and the internal temperature at 32-34℃. Softening enzyme U5 (Sichuan Desai'er Chemical Industry Co., Ltd.) 0.1-0.3%, Pingpingjia (Guangzhou Baowan Chemical Co., Ltd.) 0.2%, and ammonium chloride 0.2%. Rotate for 20 minutes; then rotate for 10 minutes and stop for 20 minutes. Repeat this process 2-4 times. Take a waste liquid sample for testing and drain the drum. The final softening bath solution pH is approximately 9.0-9.2, and the temperature is 29-30℃.

[0017] The above pre-tanning process is carried out in a rotary drum. The softened hides are placed into the drum, water is added, and the liquor ratio is controlled at 0.3-0.5. 6-16% of organic tanning agent F-90 (Stahl GmbH, Germany) is added, and the tanning time is 120-180 min. After liquor expansion, the temperature is 40℃, and the reaction time is 120-180 min. The temperature is then raised to 45℃, and the reaction time is 180-240 min. Drainage is then performed.

[0018] The above acid immersion process is carried out in a rotary drum. Water is added, the liquid ratio is controlled at 0.5-0.6%, the rotation speed is 8-10 rpm, and the internal temperature is 20-22℃. During rotation, 0.5-1.5% formic acid and 0.5-1.5% sulfuric acid diluted with 8-10 times the amount of room temperature water are added through the drum shaft hole, with a pH of 3.5-4.5. The drum is rotated for 30-60 minutes.

[0019] The above main tanning process is carried out in a rotary drum. Add 2-5% OS and 1-3% LQ-5, rotate for 30 minutes, adjust the pH to 4.0-4.5, and rotate for another 30 minutes. Next, add 10-20% bayberry tannin (Guangxi Wuming Tannin Factory), and rotate for 120-180 minutes. Then add another 10-20% bayberry tannin (Guangxi Wuming Tannin Factory), and rotate for 120-180 minutes. After tanning, add 100% water, adjust the pH to 3.0-3.5, maintain the temperature at 35-45℃, and rotate for 60 minutes. Stop the drum, let it sit overnight, and the next day rotate for 30 minutes. Drain the water, remove the hides, and let it stand for 3-7 days.

[0020] The above-mentioned chromium-free retanning is carried out in a rotary drum. The tanned wet leather is rehydrated according to conventional processes, water is added, the liquid ratio is controlled at 0.8-1.0, the rotation speed is 15 rpm, the drum internal temperature is 35℃, 0.2-2.0% modified glutaraldehyde is added, and the drum is rotated for 30 min; 0.5-5% of chromium-free multi-metal compound tanning agent (zirconium aluminum titanium compound tanning agent CAT, Mianzhu Jinkun Chemical Co., Ltd.) and 0.2-2.0% cationic oil TJ-5195 (Sichuan Tingjiang New Material Co., Ltd.) are added, and the drum is rotated for 90 min; 1% sodium formate is added, and the drum is rotated for 30 min; 0.3-0.8% sodium bicarbonate is added, the pH is adjusted to 4.1-4.2, and the drum is rotated for 60 min; 100% water is added, the temperature is raised to 40℃, and the drum is rotated for 30 min, then the drum is stopped and left overnight; the next day, the drum is rotated for 30 min, and the water is drained.

[0021] The above neutralization process is as follows: wet leather batches are squeezed, sliced, and shaved evenly according to conventional processes, then placed in a drum. Water is added, controlling the liquid ratio at 1.5, the rotation speed at 15 rpm, and the drum temperature at 35°C. Sodium formate 1% and PAK-S 1% are added, and the drum is rotated for 20 minutes. Next, sodium bicarbonate dissolved in 5 times its volume of water at 35°C is added to adjust the pH to 4.6-4.8, and the drum is rotated for 60 minutes. Finally, ZY-C (Stahl GmbH, Germany) 2% is added and evenly dispersed in 5 times its volume of water at 55°C, and the pH is adjusted to 4.6-4.8 and the temperature to 35-38°C, and the drum is rotated for 60 minutes.

[0022] The above filling and dyeing process is carried out in a rotary drum, with the liquid ratio controlled at 0.5-0.6, the rotation speed at 15 rpm, and the drum temperature at 28-35℃. 2% of Dispersible Tannin™ (Sichuan Desai Chemical Industry Co., Ltd.) is added and the drum is rotated for 30 minutes. Next, 6-18% of filler compounded in different proportions and 2-5% of dye NB (Beijing Fanbo Chemical Co., Ltd.) are added during rotation, adjusting the pH to 5.0-5.5, and the drum is rotated for 180 minutes. Then, 0.5% formic acid is added in three portions, rotating for 20 minutes each time, followed by a 30-minute pause. The final pH is 3.8-4.2.

[0023] The above fatliquoring process is carried out in the same drum and bath as the dyeing process. First, add water at 58-62℃, control the liquor ratio at 1.5-2.0, maintain the drum temperature at 50-55℃, and rotate for 10 minutes. Second, add 0.6-9.0% of synthetic fatliquoring agent SU (Xiamen Wantongli Chemical Materials Co., Ltd.), 0.3-4.5% of cow hoof oil OPE (Unit, Italy), 0.3-4.5% of lecithin BA (Zschimmer, Germany), and wool, dispersed and stirred evenly with 5 times the volume of 55℃ hot water. A fatliquoring emulsion, composed of ZBN (Biokimica, Italy) 0.3-4.5% and castor oil fatliquoring agent BCA (Yide Chemicals Co., Ltd.), was prepared and incubated for 60 minutes. Next, 150-200% hot water at 48-52℃ was added, followed by 0.5-2.0% cationic fatliquoring agent GS (Stahl, Germany), and incubated for 60 minutes. Then, 0.3% formic acid, diluted 10 times with cold water beforehand, was added in two portions and incubated for 20 minutes each time. Finally, the pH of the bath solution was measured to be 3.4-3.6, and the temperature was 50-55℃. The bath was then rinsed with 300% hot water at 55℃ for 10 minutes, and the solution was drained.

[0024] The above color matching process is carried out in the same drum as the fatliquoring process. Water is added, the bath liquid ratio is controlled at 1.5, the rotation speed is 15 rpm, and the drum internal temperature is 60℃. 1% of chromium-free multi-metal complex tanning agent (zirconium aluminum titanium complex tanning agent CAT, Mianzhu Jinkun Chemical Co., Ltd.) is added, and the drum is rotated for 20 min. Next, 0.8-1.5% of dye NB (Beijing Fanbo Chemical Co., Ltd.) is added, and the drum is rotated for 15 min. 0.8% of formic acid diluted with 10 times the amount of cold water is added, and the drum is rotated for 15 min. Next, 0.5% of NB (Beijing Fanbo Chemical Co., Ltd.) is added, and the drum is rotated for 15 min. 0.8% of formic acid diluted with 10 times the amount of cold water is added, and the drum is rotated for 15 min. Next, 0.3% of AL (Sichuan Desai Chemical Industry Co., Ltd.) is added, and the drum is rotated for 20 min. 0.5% of GS (Germany Stahl Company) is added, the pH is adjusted to 3.3-3.6, and the drum is rotated for 15 min. The drum is washed twice with 200% room temperature water for 10 min each time. The water is drained, the drum is removed, and the drum is connected.

[0025] The above-mentioned water-squeezing and stretching process is carried out on a reciprocating water-squeezing and stretching machine at a pressure of 30 bar and a feeding speed of 5-25 m / min. The moisture content of the raw leather after treatment is 50-55%.

[0026] The drying process is as follows: First, vacuum drying is carried out in a vacuum dryer (fog plate) with the following parameters: temperature 45℃, time 500s, negative pressure 23-26Mbar, and the moisture content of the raw leather is 23-30%. Second, hanging drying is carried out on a hanging drying line for 24 hours, and the moisture content of the raw leather is less than 14% after drying. Finally, drying is carried out in a constant temperature and humidity oven with the following oven temperatures for the three stages: 37℃, 42℃, and 48℃, oven humidity of approximately 33%, drying time of approximately 12 hours, drying time of 6 minutes and dehumidification time of 10 minutes. After the process, the raw leather is smooth and the moisture content is approximately 7-9%.

[0027] The above-mentioned rehumidification and softening process involves the following steps: First, the dried raw leather undergoes a rehumidification treatment, aiming for a moisture content of approximately 28-32%. Second, it is softened using a vibrating softening machine with the following process parameters: conveyor speed 9.5 m / min, 5 stages, resulting in a raw leather moisture content of 28%–32%. Subsequently, it is softened by tumbling in a stainless steel octagonal tumbling drum with the following process parameters: drum speed 15 r / min, drum temperature 25-30℃, time 6 hours, automatic intermittent forward and reverse rotation, resulting in a raw leather moisture content of 20%–25%.

[0028] The above-mentioned flattening process involves: First, stretching the leather on a horizontal stretching machine with the following parameters: temperature 60℃, stretching distance 6cm, clamping distance 10-12cm, and the time for the raw leather to pass through the oven for 20 minutes, resulting in a moisture content of 14%-18% for the processed raw leather. Second, calendering is performed on a pass-through ironing machine with the following parameters: temperature 120℃, pressure 30kg, and speed 8m / min, requiring the raw leather to have a clear grain, a smooth feel, and uniform gloss.

[0029] The coating process described above is as follows: primer → calendering → polishing → troweling → topcoat 1 → troweling → topcoat 2 → troweling → topcoat → calendering → troweling → calendering → softening. The coating is performed using air spraying on a spraying machine with the following parameters: pump pressure 3.0 bar, 12 spray gun sections, atomizing air pressure 5.0 bar, spray gun rotation speed 17–18 r / min, and conveyor belt speed 5–6 m / min. Calendering is performed on a plate iron with the following parameters: glossy plate surface temperature 100℃, pressure 30 kg, and time 2 s. Polishing is performed on a polishing machine with the following parameters: feed roller speed 8 m / min, polishing roller speed 8.0 m / min, and distance between the feed roller and polishing roller 4–5 mm. Troweling is performed on a through-feed iron with the following parameters: temperature 120℃, pressure 30 kg, and speed 8 m / min.

[0030] The above-mentioned finished leather: The coated raw leather is calendered, softened, trimmed, measured and packaged to obtain finished leather. Calendering is carried out on a plate ironing machine with the following process parameters: glossy plate surface temperature 100℃, pressure 30kg, time 2s; Softening is carried out on a vibrating softening machine with the following process parameters: conveying speed 9.5m / min, level 5.

[0031] In a further improvement, the scraps obtained after the above-mentioned regularization and the second layer of leather obtained after splitting are used to make leather collagen fiber aggregates or industrial collagen.

[0032] Method for producing skin collagen fiber aggregates: deliming → softening → acid soaking → drying and slitting → skin collagen fiber aggregates. The deliming, softening, acid soaking, and drying processes can be performed according to the above steps, and the aggregates can be cut into the appropriate specifications as needed.

[0033] Deashing: The scraps and second layers obtained after straightening and splitting are put into the drum, water is added, the liquid ratio is controlled at 1.5-2.0, the internal temperature is 28-30℃, 1.0% of surfactant Pingpingjia (Guangzhou Baowan Chemical Co., Ltd.) is added, and 0.3% of deashing agent (Sichuan Desail Chemical Industry Co., Ltd.)™ is added. The drum is rotated for 10-20 minutes, and then rinsed with running water for 10 minutes. Then, 1.2-1.3% of deashing agent™ (Sichuan Desail Chemical Industry Co., Ltd.) and 0.15% sodium metabisulfite are added, and the drum is rotated for 20 minutes. The pH of the bath solution at the end of the deashing process is 8.5-9.0, and then rinsed with running water for 10 minutes.

[0034] Softening: This process is carried out in the same drum as deashing. First, the deashed scraps and second-layer skin are put into the drum. The liquid ratio is controlled at 1.0-1.2, the rotation speed is 5-6 rpm, and the internal temperature is 32-34℃. 0.1-0.3% softening enzyme U5 (Sichuan Desaier Chemical Industry Co., Ltd.), 0.2% Pingpingjia (Guangzhou Baowan Chemical Co., Ltd.), and 0.2% ammonium chloride are added. The drum is rotated for 20 minutes. Then, the drum is rotated for 10 minutes and stopped for 20 minutes. This process is repeated 2-4 times. The pH of the bath solution at the end of the softening process is about 9.0-9.2. The solution is then drained.

[0035] Acid soaking: This is carried out in a softening drum. Water is added, and the liquid ratio is controlled at 0.5-0.6%. The rotation speed is 8-10 rpm, and the internal temperature is 20-22℃. 5-10% sodium chloride is added, and the drum is rotated for 10 minutes. During rotation, 0.5-1.5% formic acid and 0.5-1.5% sulfuric acid diluted with 8-10 times the amount of room temperature water are added through the drum shaft hole, with a pH of 3.5-4.5. The drum is rotated for 30-60 minutes. Drain the water. Hang the leather to air dry, freeze-dry and store. Cut the leather collagen aggregates as required.

[0036] Further extraction of industrial collagen: Place the above-mentioned skin collagen aggregates into a rotating drum, add ice water, control the liquid-to-liquid ratio at 2.5-3.5, add 0.8-1.5% salt, and rotate for 90-180 minutes until the skin collagen aggregates are uniformly colored, semi-transparent, and slightly swollen. Drain the water; add 0.5M acetic acid solution at a liquid-to-liquid ratio of 3-30, adjust the pH to 2-2.5, and soak for 90-180 minutes until transparent; continue adding 50-500% of 0.5M acetic acid solution, stirring thoroughly; add NaOH solution dropwise until the pH is neutral; add 1.5M NaCl, and salt out for 24 hours to obtain a white flocculent substance; add water, control the liquid-to-liquid ratio at 2-5, and adjust the solution temperature to 45-55℃ and pH... 5-6, add papain (Shanghai Guchen Biotechnology Co., Ltd.) 6-8, enzymatically hydrolyze for 300-480 min, then heat to 95-100℃ and rotate for 10 min; take the filtrate, and spray dry or freeze dry to obtain collagen.

[0037] Further improvements were made to the compound filler formulation in the above-mentioned filling and dyeing processes: the amount of protein filler DESOATEN FB (Sichuan Desai'er Chemical Industry Co., Ltd.) was 0.5%, and the amount of synthetic tanning agent was... HL (BASF, Germany) was used at a rate of 3.57% in synthetic resin. The dosage of HB (Trumpler, Germany) is 3.95%, and the dosage of the vegetable tanning agent UNITANATO (Unit, Italy) is 0.98%.

[0038] Further improvements are made to the primer formulation in the above coating process as follows: 100 parts water; 25-35 parts waterborne polyurethane (WX1418, TFL GmbH, Germany); 20-30 parts waterborne casein (BI-596, Stahl GmbH, Germany); 15-30 parts oil emulsion (Oil Ground, BASF GmbH, Germany); 6-10 parts wax emulsion (RODA Wax DW 4081, TFL GmbH, Germany); 10-20 parts pigment paste (Sichuan Dawei Technology Co., Ltd.); one primer coat with a coating weight of 10g / SF.

[0039] Further improvements are made to the above coating process, where the topcoat formulation is as follows: 100 parts water; 50-80 parts waterborne acrylic resin (SB150, LANXESS, Germany); 5-10 parts oil emulsion (RODA Oil DW 4050, TFL, Germany); 5-10 parts wax emulsion (RODA Wax DW 4081, TFL, Germany); 5-10 parts graphene-modified waterborne silicone; and two topcoat applications, with a total coating weight of 15 g / SF.

[0040] Further improvements are made to the topcoat formulation in the above coating process as follows: 100 parts water; 10-30 parts graphene-modified waterborne organosilicon; one topcoat application with a coating amount of 8 g / SF.

[0041] Further improvements are made to the above-mentioned topcoat formulation for the preparation of graphene-modified waterborne organosilicon: 10-20 parts of graphene oxide dispersion (Wacker Chemicals (China) Co., Ltd., Shanghai), 20-40 parts of γ-aminopropyltriethoxysilane (Wacker Chemicals (China) Co., Ltd., Shanghai), 30-60 parts of triethylamine, and 3-5 parts of glycerol are uniformly dispersed under ultrasonication, and then dispersed with 10-20 parts of organosilicon feel agent (SF, Trumpler GmbH, Germany) under ultrasonication to obtain graphene-modified waterborne organosilicon dispersion.

[0042] As can be seen from the above description of the structure of the present invention, compared with the prior art, the present invention has the following advantages:

[0043] 1. This application uses sulfur-free hair removal (compound enzyme + keratinase + tourmaline powder), salt-free pickling (first F-90 pre-tanning, then pickling without adding salt), and chromium-free tanning (organic tanning + vegetable tanning) / retanning technology (aldehyde tanning + metal tanning). The patented technology can guarantee the process effect and solve the problem of introducing harmful chemical materials from the source.

[0044] 2. The wet dyeing and finishing and dry finishing processes of this application adopt a simplified process with less filler and grease. Due to the reasonable combination, the cost is low, but the performance is good and can meet the production requirements. The coating system is water-based, with less VOC generation. Graphene is introduced into the coating agent, resulting in low coating amount and good coating effect.

[0045] 3. This application introduces a standardization process, cutting irregular cowhide into regular rectangles (reducing the area by approximately 1 / 4), resulting in more consistent thickness and a more uniform density of collagen fiber weaving. This makes subsequent processing more controllable and easier to handle. Since special areas do not require special treatment, the amount of chemicals used is reduced by approximately 1 / 3, while the resulting samples exhibit better sensory and physical-mechanical properties. Due to the more standardized shape, trimming is virtually unnecessary, reducing the number of steps and waste generated from trimming (0.5-1 kg of trimming waste per hide).

[0046] 4. Combining 1 and 2, the scraps obtained from regularization and the split leather obtained from splitting are free of chromium and sulfur, and have higher use value. They can be used to extract higher quality skin collagen aggregates and industrial collagen products, thereby increasing the added value of scraps and split leather.

[0047] 5. Traditional chrome tanning produces hazardous industrial solid waste. The shavings produced by the patented technology of this application are chromium-free, non-toxic, easy to handle, and can be degraded using conventional methods to extract industrial collagen, thus having a wider range of applications. Attached Figure Description

[0048] Figure 1 This is a schematic diagram of the structure of the cowhide used in this application.

[0049] Figure 2 This is a schematic diagram of the cowhide and the cut rectangle structure of this application. Detailed Implementation

[0050] The specific embodiments of the present invention will now be described with reference to the accompanying drawings.

[0051] Example 1:

[0052] A high-utilization eco-friendly leather manufacturing process, using salted wet cowhide as raw material, includes the following steps: pre-soaking → fleshing → main soaking → enzymatic hair removal → liming → regularization → splitting → deliming → softening → pre-tanning → pickling → main tanning → settling → chromium-free retanning → neutralization → filling and dyeing → fatliquoring → coloring → squeezing and stretching → drying → rewetting → softening → flattening → finishing → finished leather;

[0053] The above pre-soaking process is as follows: First, put the salted wet cowhide into the drum, add water, control the liquid ratio at 1.5-2.0, rotate at 3 rpm, and keep the temperature at room temperature; second, add 0.1% of the penetrant Desoagen WT-H (Sichuan Desai'er Chemical Industry Co., Ltd.), 0.1% of the bactericide ME (BASF, Germany), 0.2% of the degreasing agent FG-B (Sichuan Dawei Technology Co., Ltd.), and 0.3% of the soda ash, rotate for 10 minutes, stop for 30 minutes, repeat 6 times, stop the drum overnight, and the next day, rotate for 30 minutes and drain.

[0054] The above process involves feeding 7-8 hides per minute to remove the subcutaneous membrane from the main parts of the hide, leaving the meat surface whitish, with only a small amount of membrane remaining at the edges and corners, and cleaning the hair surface thoroughly. Also, remove any meat scraps, whiskers, cow tail, ears, and hooves around the hide.

[0055] The above-mentioned main soaking process is as follows: First, the pre-soaked leather is placed into the drum, water is added, the liquid ratio is controlled at 1.8-2.0, the rotation speed is 3 rpm, and the temperature is room temperature; Second, 0.3% of Desoagen WT-H (Sichuan Desai'er Chemical Industry Co., Ltd.), 0.5% of Dowelleym SD (Sichuan Dawei Technology Co., Ltd.), 0.1% of ME (BASF, Germany), 0.3% of FG-B (Sichuan Dawei Technology Co., Ltd.), and 0.2% of soda ash are added. The drum is rotated for 10 minutes and stopped for 20 minutes, repeated 4-6 times, then rotated for 10 minutes and stopped for 50 minutes, repeated 6-8 times. The drum is then left to stand overnight. The next day, the drum is rotated for 30 minutes, and the water is drained.

[0056] The above-mentioned enzymatic hair removal process is as follows: First, immerse the soaked bare skin in the drum, control the liquid ratio at 0.8-1.0, the rotation speed at 6-8 rpm, the internal temperature at 26-28℃, and adjust the pH to 9.0-9.5; add 1.5% hair removal compound enzyme, 0.1% keratinase K (Xiasheng Biotechnology Development Co., Ltd.), and 1.0% tourmaline powder (Lingshou County Baifei Mineral Products Processing Plant), and rotate for 60-180 minutes; when the hair removal rate is >90%, control the liquid ratio at 0.2-0.3, the rotation speed at 3-5 rpm, the internal temperature at 23-26℃, add 2.0% quicklime and 0.2% sodium hydroxide, and rotate for 60-120 minutes;

[0057] The above-mentioned liming process: After hair removal, add water to make the liquid ratio reach 2.0-2.5, and add 0.15% dissolved sodium hydroxide while rotating. First rotate for 60 minutes, then rotate for 5 minutes and stop at 55 degrees Celsius. Repeat this process 4-6 times, stop the drum and let it sit overnight. The next day, rotate for 30 minutes and drain the water.

[0058] The above-mentioned standardization involves: trimming off the edges and corners of the raw hide after soaking in ash to form a more regular rectangle; collecting the trimmed scraps and extracting collagen or collagen aggregates;

[0059] The above splitting process is carried out on a splitting machine with a leather supply speed of approximately 7-8 sheets / min. The thickness of the top-grain grey leather is determined according to a grey leather to blue wet leather ratio of approximately 1.0:0.7, which is generally 2.2-2.4mm. The thickness of the entire leather is basically consistent.

[0060] The above deashing process is as follows: First, the cleaned and split limed bare skin is placed into a rotating drum, with the liquid ratio controlled at 2.0-2.2, the rotation speed at 5-6 rpm, and the internal temperature at 28-29℃. 0.3% of deashing agent TM (Sichuan Desail Chemical Industry Co., Ltd.) is added, and the drum is rotated for 15 minutes. Second, 1.3% of deashing agent TM (Sichuan Desail Chemical Industry Co., Ltd.) and 0.15% sodium metabisulfite are added, and the drum is rotated for 20 minutes. At the end of the deashing process, the pH of the bath solution is 8.8-9.0, the temperature is 28-29℃, the bare skin has basically eliminated its swelling state, the particle surface is clean and fine, and the buttock incision is examined with phenolphthalein, which shows a purplish-red color, is fully transparent or leaves a 1 / 2 line in the center.

[0061] The softening process is as follows: First, the deashed bare hides are placed into a rotating drum, with the liquid ratio controlled at 1.0-1.2, the rotation speed at 5-6 rpm, and the internal temperature at 32-34℃. Softening enzyme U5 (Sichuan Desai'er Chemical Industry Co., Ltd.) 0.1-0.3%, Pingpingjia (Guangzhou Baowan Chemical Co., Ltd.) 0.2%, and ammonium chloride 0.2%. Rotate for 20 minutes; then rotate for 10 minutes and stop for 20 minutes. Repeat this process 2-4 times. Take a waste liquid sample for testing and drain the drum. The final softening bath solution pH is approximately 9.0-9.2, and the temperature is 29-30℃.

[0062] The above pre-tanning process is carried out in a rotary drum. The softened hides are placed into the drum, water is added, and the liquor ratio is controlled at 0.3-0.5. 6-16% of organic tanning agent F-90 (Stahl GmbH, Germany) is added, and the tanning time is 120-180 min. After liquor expansion, the temperature is 40℃, and the reaction time is 120-180 min. The temperature is then raised to 45℃, and the reaction time is 180-240 min. Drainage is then performed.

[0063] The above acid immersion is carried out in a rotary drum. Water is added, the liquid ratio is controlled at 0.5-0.6%, the rotation speed is 8-10 rpm, and the internal temperature is 20-22℃. During rotation, 0.5% formic acid and 1.5% sulfuric acid diluted with 8-10 times room temperature water are added through the shaft hole of the rotary drum, with a pH of 3.5-4.5. The drum is rotated for 30-60 minutes.

[0064] The above main tanning process is carried out in a rotary drum. Add 2% OS and 3% LQ-5, rotate for 30 minutes, adjust the pH to 4.0-4.5, and rotate for another 30 minutes. Next, add 10-20% bayberry tannin (Guangxi Wuming Tannin Factory), and rotate for 120-180 minutes. Then add another 10-20% bayberry tannin (Guangxi Wuming Tannin Factory), and rotate for 120-180 minutes. After tanning, add 100% water, adjust the pH to 3.0-3.5, maintain the temperature at 35-45℃, and rotate for 60 minutes. Stop the drum, let it sit overnight, and the next day rotate for 30 minutes. Drain the water, remove the hides, and let it stand for 3-7 days.

[0065] The above-mentioned chromium-free retanning is carried out in a rotary drum. The tanned wet leather is rehydrated according to conventional processes, water is added, the liquid ratio is controlled at 0.8-1.0, the rotation speed is 15 rpm, the drum internal temperature is 35℃, 0.2% modified glutaraldehyde is added, and the drum is rotated for 30 min; 0.5% of chromium-free multi-metal compound tanning agent (zirconium aluminum titanium compound tanning agent CAT, Mianzhu Jinkun Chemical Co., Ltd.) and 2.0% cationic oil TJ-5195 (Sichuan Tingjiang New Material Co., Ltd.) are added, and the drum is rotated for 90 min; 1% sodium formate is added, and the drum is rotated for 30 min; 0.3% sodium bicarbonate is added, the pH is adjusted to 4.1-4.2, and the drum is rotated for 60 min; 100% water is added, the temperature is raised to 40℃, and the drum is rotated for 30 min, then the drum is stopped and left overnight; the next day, the drum is rotated for 30 min, and the water is drained.

[0066] The above neutralization process is as follows: wet leather batches are squeezed, sliced, and shaved evenly according to conventional processes, then placed in a drum. Water is added, controlling the liquid ratio at 1.5, the rotation speed at 15 rpm, and the drum temperature at 35°C. Sodium formate 1% and PAK-S 1% are added, and the drum is rotated for 20 minutes. Next, sodium bicarbonate dissolved in 5 times its volume of water at 35°C is added to adjust the pH to 4.6-4.8, and the drum is rotated for 60 minutes. Finally, ZY-C (Stahl GmbH, Germany) 2% is added and evenly dispersed in 5 times its volume of water at 55°C, and the pH is adjusted to 4.6-4.8 and the temperature to 35-38°C, and the drum is rotated for 60 minutes.

[0067] The above filling and dyeing processes were carried out in a rotary drum, with the liquid ratio controlled at 0.5-0.6, the rotation speed at 15 rpm, and the drum temperature at 28-35℃. 2% of Dispersible Tannin™ (Sichuan Desai Chemical Industry Co., Ltd.) was added and the drum was rotated for 30 minutes. Next, 6-18% of filler compounded in different proportions and 2% of dye NB (Beijing Fanbo Chemical Co., Ltd.) were added during rotation, and the pH was adjusted to 5.0-5.5, and the drum was rotated for 180 minutes. Then, 0.5% formic acid was added in three portions, rotating for 20 minutes each time, followed by a 30-minute pause. The final pH was 3.8-4.2.

[0068] The above fatliquoring process is carried out in the same drum and bath as the dyeing process. First, add water at 58-62℃, control the liquor ratio at 1.5-2.0, maintain the drum temperature at 50-55℃, and rotate for 10 minutes. Second, add 6.0% synthetic fatliquoring agent SU (Xiamen Wantongli Chemical Materials Co., Ltd.), 3.5% cow hoof oil OPE (Unit, Italy), 0.3% lecithin BA (Zschimmer, Germany), and wool, dispersed and stirred evenly with 5 times the volume of 55℃ hot water. A fatliquoring emulsion, composed of 2.5% ZBN (Biokimica, Italy) and 4.5% BCA (Yide Chemicals Co., Ltd., Italy), was prepared and incubated for 60 minutes. Next, 150-200% hot water at 48-52℃ was added, followed by 2.0% cationic fatliquoring agent GS (Stahl, Germany), and incubated for 60 minutes. Then, 0.3% formic acid, diluted 10 times with cold water beforehand, was added in two portions and incubated for 20 minutes each time. Finally, the pH of the bath was measured to be 3.4-3.6, and the temperature was 50-55℃. The bath was then rinsed with 300% hot water at 55℃ for 10 minutes, and the solution was drained.

[0069] The above color matching process is carried out in the same drum as the fatliquoring process. Water is added, the bath liquid ratio is controlled at 1.5, the rotation speed is 15 rpm, and the drum internal temperature is 60℃. 1% of chromium-free multi-metal complex tanning agent (zirconium aluminum titanium complex tanning agent CAT, Mianzhu Jinkun Chemical Co., Ltd.) is added, and the drum is rotated for 20 min. Next, 0.8-1.5% of dye NB (Beijing Fanbo Chemical Co., Ltd.) is added, and the drum is rotated for 15 min. 0.8% of formic acid diluted with 10 times the amount of cold water is added, and the drum is rotated for 15 min. Next, 0.5% of NB (Beijing Fanbo Chemical Co., Ltd.) is added, and the drum is rotated for 15 min. 0.8% of formic acid diluted with 10 times the amount of cold water is added, and the drum is rotated for 15 min. Next, 0.3% of AL (Sichuan Desai Chemical Industry Co., Ltd.) is added, and the drum is rotated for 20 min. 0.5% of GS (Germany Stahl Company) is added, the pH is adjusted to 3.3-3.6, and the drum is rotated for 15 min. The drum is washed twice with 200% room temperature water for 10 min each time. The water is drained, the drum is removed, and the drum is connected.

[0070] The above-mentioned water-squeezing and stretching process is carried out on a reciprocating water-squeezing and stretching machine at a pressure of 30 bar and a feeding speed of 5-25 m / min. The moisture content of the raw leather after treatment is 50-55%.

[0071] The drying process is as follows: First, vacuum drying is carried out in a vacuum dryer (fog plate) with the following parameters: temperature 45℃, time 500s, negative pressure 23-26Mbar, and the moisture content of the raw leather is 23-30%. Second, hanging drying is carried out on a hanging drying line for 24 hours, and the moisture content of the raw leather is less than 14% after drying. Finally, drying is carried out in a constant temperature and humidity oven with the following oven temperatures for the three stages: 37℃, 42℃, and 48℃, oven humidity of approximately 33%, drying time of approximately 12 hours, drying time of 6 minutes and dehumidification time of 10 minutes. After the process, the raw leather is smooth and the moisture content is approximately 7-9%.

[0072] The above-mentioned rehumidification and softening process involves the following steps: First, the dried raw leather undergoes a rehumidification treatment, aiming for a moisture content of approximately 28-32%. Second, it is softened using a vibrating softening machine with the following process parameters: conveyor speed 9.5 m / min, 5 stages, resulting in a raw leather moisture content of 28%–32%. Subsequently, it is softened by tumbling in a stainless steel octagonal tumbling drum with the following process parameters: drum speed 15 r / min, drum temperature 25-30℃, time 6 hours, automatic intermittent forward and reverse rotation, resulting in a raw leather moisture content of 20%–25%.

[0073] The above-mentioned flattening process involves: First, stretching the leather on a horizontal stretching machine with the following parameters: temperature 60℃, stretching distance 6cm, clamping distance 10-12cm, and the time for the raw leather to pass through the oven for 20 minutes, resulting in a moisture content of 14%-18% for the processed raw leather. Second, calendering is performed on a pass-through ironing machine with the following parameters: temperature 120℃, pressure 30kg, and speed 8m / min, requiring the raw leather to have a clear grain, a smooth feel, and uniform gloss.

[0074] The coating process described above is as follows: primer → calendering → polishing → troweling → topcoat 1 → troweling → topcoat 2 → troweling → topcoat → calendering → troweling → calendering → softening. The coating is performed using air spraying on a spraying machine with the following parameters: pump pressure 3.0 bar, 12 spray gun sections, atomizing air pressure 5.0 bar, spray gun rotation speed 17–18 r / min, and conveyor belt speed 5–6 m / min. Calendering is performed on a plate iron with the following parameters: glossy plate surface temperature 100℃, pressure 30 kg, and time 2 s. Polishing is performed on a polishing machine with the following parameters: feed roller speed 8 m / min, polishing roller speed 8.0 m / min, and distance between the feed roller and polishing roller 4–5 mm. Troweling is performed on a through-feed iron with the following parameters: temperature 120℃, pressure 30 kg, and speed 8 m / min.

[0075] The primer formulation in the above coating process is as follows: 100 parts water; 25 parts waterborne polyurethane (WX1418, TFL GmbH, Germany); 20 parts waterborne casein (BI-596, Stahl GmbH, Germany); 30 parts oil emulsion (Oil Ground, BASF GmbH, Germany); 10 parts wax emulsion (RODA Wax DW 4081, TFL GmbH, Germany); 10 parts pigment paste (Sichuan Dawei Technology Co., Ltd.); one primer coat is applied, with a coating weight of 10g / SF.

[0076] The topcoat formulation in the above coating process is as follows: 100 parts water; 50 parts water-based acrylic resin (SB 150, LANXESS, Germany); 10 parts oil emulsion (RODA Oil DW 4050, TFL, Germany); 10 parts wax emulsion (RODA Wax DW 4081, TFL, Germany); 5 parts graphene-modified water-based silicone; the topcoat is applied twice, with a total coating weight of 15 g / SF.

[0077] The topcoat formulation in the above coating process is: 100 parts water; 10 parts graphene-modified waterborne organosilicon; one topcoat application with a coating amount of 8g / SF.

[0078] The above-mentioned finished leather: The coated raw leather is calendered, softened, trimmed, measured and packaged to obtain finished leather. Calendering is carried out on a plate ironing machine with the following process parameters: glossy plate surface temperature 100℃, pressure 30kg, time 2s; Softening is carried out on a vibrating softening machine with the following process parameters: conveying speed 9.5m / min, level 5.

[0079] The scraps obtained after the above-mentioned regularization and the second layer of leather obtained after splitting are used to make leather collagen fiber aggregates or industrial collagen.

[0080] Method for producing skin collagen fiber aggregates: deliming → softening → acid soaking → drying and slitting → skin collagen fiber aggregates. The deliming, softening, acid soaking, and drying processes can be performed according to the above steps, and the aggregates can be cut into the appropriate specifications as needed.

[0081] Deashing: The scraps and second layers obtained after straightening and splitting are put into the drum, water is added, the liquid ratio is controlled at 1.5-2.0, the internal temperature is 28-30℃, 1.0% of surfactant Pingpingjia (Guangzhou Baowan Chemical Co., Ltd.) is added, and 0.3% of deashing agent (Sichuan Desail Chemical Industry Co., Ltd.)™ is added. The drum is rotated for 10-20 minutes, and then rinsed with running water for 10 minutes. Then, 1.2-1.3% of deashing agent™ (Sichuan Desail Chemical Industry Co., Ltd.) and 0.15% sodium metabisulfite are added, and the drum is rotated for 20 minutes. The pH of the bath solution at the end of the deashing process is 8.5-9.0, and then rinsed with running water for 10 minutes.

[0082] Softening: This process is carried out in the same drum as deashing. First, the deashed scraps and second-layer skin are put into the drum. The liquid ratio is controlled at 1.0-1.2, the rotation speed is 5-6 rpm, and the internal temperature is 32-34℃. 0.1-0.3% softening enzyme U5 (Sichuan Desaier Chemical Industry Co., Ltd.), 0.2% Pingpingjia (Guangzhou Baowan Chemical Co., Ltd.), and 0.2% ammonium chloride are added. The drum is rotated for 20 minutes. Then, the drum is rotated for 10 minutes and stopped for 20 minutes. This process is repeated 2-4 times. The pH of the bath solution at the end of the softening process is about 9.0-9.2. The solution is then drained.

[0083] Acid soaking: This is carried out in a softening drum. Water is added, and the liquid ratio is controlled at 0.5-0.6%. The rotation speed is 8-10 rpm, and the internal temperature is 20-22℃. 5-10% sodium chloride is added, and the drum is rotated for 10 minutes. During rotation, 0.5-1.5% formic acid and 0.5-1.5% sulfuric acid diluted with 8-10 times the amount of room temperature water are added through the drum shaft hole, with a pH of 3.5-4.5. The drum is rotated for 30-60 minutes. Drain the water. Hang the leather to air dry, freeze-dry and store. Cut the leather collagen aggregates as required.

[0084] Further extraction of industrial collagen: Place the above-mentioned skin collagen aggregates into a rotating drum, add ice water, control the liquid-to-liquid ratio at 2.5-3.5, add 0.8-1.5% salt, and rotate for 90-180 minutes until the skin collagen aggregates are uniformly colored, semi-transparent, and slightly swollen. Drain the water; add 0.5M acetic acid solution at a liquid-to-liquid ratio of 3-30, adjust the pH to 2-2.5, and soak for 90-180 minutes until transparent; continue adding 50-500% of 0.5M acetic acid solution, stirring thoroughly; add NaOH solution dropwise until the pH is neutral; add 1.5M NaCl, and salt out for 24 hours to obtain a white flocculent substance; add water, control the liquid-to-liquid ratio at 2-5, and adjust the solution temperature to 45-55℃ and pH... 5-6, add papain (Shanghai Guchen Biotechnology Co., Ltd.) 6-8, enzymatically hydrolyze for 300-480 min, then heat to 95-100℃ and rotate for 10 min; take the filtrate, and spray dry or freeze dry to obtain collagen.

[0085] The compound filler ratio in the above filling and dyeing processes is as follows: the amount of protein filler DESOATEN FB (Sichuan Desai'er Chemical Industry Co., Ltd.) is 0.5%, and the amount of synthetic tanning agent is... HL (BASF, Germany) was used at a rate of 3.57% in synthetic resin. The dosage of HB (Trumpler, Germany) is 3.95%, and the dosage of the vegetable tanning agent UNITAN ATO (Unit, Italy) is 0.98%.

[0086] The graphene-modified waterborne organosilicon of the above top coating formulation was prepared as follows: 20 parts of graphene oxide dispersion (Shanghai Wacker Chemicals (China) Co., Ltd.), 20 parts of γ-aminopropyltriethoxysilane (Shanghai Wacker Chemicals (China) Co., Ltd.), 30 parts of triethylamine, and 3 parts of glycerol were dispersed evenly under ultrasonication, and then dispersed with 10 parts of organosilicon feel agent (SF, Trumpler GmbH, Germany) under ultrasonication to obtain graphene-modified waterborne organosilicon dispersion.

[0087] Example 2:

[0088] This embodiment is basically the same as Embodiment 1, except for the following differences:

[0089] The primer formulation in the above coating process is as follows: 100 parts water; 35 parts waterborne polyurethane (WX1418, TFL GmbH, Germany); 30 parts waterborne casein (BI-596, Stahl GmbH, Germany); 15 parts oil emulsion (Oil Ground, BASF GmbH, Germany); 6 parts wax emulsion (RODA Wax DW 4081, TFL GmbH, Germany); 20 parts pigment paste (Sichuan Dawei Technology Co., Ltd.); one primer coat is applied, with a coating weight of 10g / SF.

[0090] The topcoat formulation in the above coating process is as follows: 100 parts water; 80 parts water-based acrylic resin (SB 150, LANXESS, Germany); 5 parts oil emulsion (RODA Oil DW 4050, TFL, Germany); 5 parts wax emulsion (RODA Wax DW 4081, TFL, Germany); 10 parts graphene-modified water-based silicone; the topcoat is applied twice, with a total coating weight of 15 g / SF.

[0091] The topcoat formulation in the above coating process is: 100 parts water; 30 parts graphene-modified waterborne organosilicon; one topcoat application with a coating amount of 8g / SF.

[0092] The graphene-modified waterborne organosilicon of the above top coating formulation was prepared by dispersing 10 parts of graphene oxide dispersion (Shanghai Wacker Chemicals (China) Co., Ltd.), 40 parts of γ-aminopropyltriethoxysilane (Shanghai Wacker Chemicals (China) Co., Ltd.), 60 parts of triethylamine, and 5 parts of glycerol under ultrasonication. Then, it was ultrasonically dispersed with 20 parts of organosilicon feel agent (SF, Trumpler GmbH, Germany) to obtain graphene-modified waterborne organosilicon dispersion.

[0093] The above are merely specific embodiments of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial modifications made to the present invention using this concept shall be considered as infringing upon the protection scope of the present invention.

Claims

1. A high-utilization eco-friendly leather manufacturing process, using salted wet cowhide as raw material, characterized in that, The process includes the following steps: pre-soaking → fleshing → main soaking → enzymatic hair removal → liming → leveling → splitting → deliming → softening → pre-tanning → pickling → main tanning → settling → chromium-free retanning → neutralization → filling and dyeing → fatliquoring → over-dyeing → squeezing and stretching → drying → rewetting → softening → flattening → finishing → finished leather. The pre-soaking process involves: first, placing the salted and wet cowhide into the drum, adding water, controlling the liquid ratio at 1.5-2.0, rotating at 3 rpm, and maintaining room temperature; second, adding 0.1% of the penetrant Desoagen WT-H, 0.1% of the bactericide ME, 0.2% of the degreasing agent FG-B, and 0.3% of the soda ash, rotating for 10 minutes, stopping for 30 minutes, repeating this process 4-6 times, stopping the drum overnight, and then rotating it for 30 minutes the next day to drain the water. The flesh removal process involves feeding 7-8 skins per minute, removing the subcutaneous membrane from the main parts of the skin, leaving the fleshy side whitish, with only some membrane remaining at the edges and corners, and cleaning the rough side thoroughly. Remove the meat scraps, whiskers, cow tail, cow ears, and hooves around the fur; The main soaking process is as follows: First, the pre-soaked leather is placed in the drum, water is added, the liquid ratio is controlled at 1.8-2.0, the rotation speed is 3 rpm, and the temperature is room temperature; Second, 0.3-0.5% of the penetrant Desoagen WT-H, 0.3-0.5% of the soaking enzyme DowelleymSD, 0.1-0.3% of the bactericide ME, 0.1-0.3% of the degreasing agent FG-B, and 0.2-0.4% of the soda ash are added. The drum is rotated for 10 minutes and stopped for 20 minutes, repeated 4-6 times, then rotated for 10 minutes and stopped for 50 minutes, repeated 6-8 times. The drum is left to stand overnight. The next day, the drum is rotated for 30 minutes, and the water is drained. The enzymatic hair removal process is as follows: First, soak the bare skin in water and place it in a drum. Control the liquid ratio at 0.8-1.0, the rotation speed at 6-8 rpm, the internal temperature at 26-28 ℃, and adjust the pH to 9.0-9.

5. Add 0.5-1.5% hair removal compound enzyme, 0.1-0.5% keratinase, and 0.5-1.0% tourmaline powder, and rotate for 60-180 minutes. When the hair removal rate is >90%, control the liquid ratio at 0.2-0.3, the rotation speed at 3-5 rpm, the internal temperature at 23-26 ℃, and add 2.0% quicklime and 0.15-0.2% sodium hydroxide, and rotate for 60-120 minutes. The process of liming involves adding water after hair removal to achieve a liquid-to-water ratio of 2.0-2.5, and adding dissolved sodium hydroxide while rotating the solution. 0.15-0.2%, first rotate for 60 minutes, then rotate for 5 minutes and stop for 55 minutes, rotate 4-6 times, stop the drum overnight, the next day, rotate for 30 minutes and drain; The term "regularity" refers to the process of trimming the edges and corners of the raw leather after soaking in ash, resulting in a more regular rectangle. Collect the cut-off scraps and extract collagen or collagen aggregates; The splitting process is carried out on a splitting machine at a feed rate of 7-8 hides / min. The thickness of the top-grain grey hide is determined according to a ratio of grey hide to wet blue leather of 1.0:0.7, ensuring that the thickness of the entire hide is uniform. The deashing process is as follows: First, the cleaned and split limed bare skin is placed into a rotating drum, with the liquid ratio controlled at 2.0-2.2, the rotation speed at 5-6 rpm, and the internal temperature at 28-29 ℃. 0.3% of deashing agent TM is added, and the drum is rotated for 15 min. Second, 1.2-1.3% of deashing agent TM and 0.15% sodium metabisulfite are added, and the drum is rotated for 20 min. At the end of the deashing process, the pH of the bath solution is 8.8-9.0, and the temperature is 28-29 ℃. The swelling state is eliminated, and the grain surface is clean and fine. The buttock incision is examined with phenolphthalein and appears purplish-red, fully transparent, or with a 1 / 2 line remaining in the center. The softening process is as follows: First, the deashed bare hides are placed into a rotating drum, with the liquid ratio controlled at 1.0-1.2, the rotation speed at 5-6 rpm, and the internal temperature at 32-34 ℃. Softening enzyme U5 0.1-0.3%, Pingping 0.2%, and ammonium chloride 0.2% are added, and the drum is rotated for 20 min. Then, the drum is rotated for 10 min, stopped for 20 min, and this process is repeated 2-4 times. Waste liquid samples are collected for testing and the drum is emptied. The final softening bath solution has a pH of 9.0-9.2 and a temperature of 29-30 ℃. The pre-tanning process is carried out in a rotary drum. The softened hides are placed into the drum, water is added, and the liquor ratio is controlled at 0.3-0.

5. Organic tanning agent F-90 6-16% is added, and the tanning time is 120-180 min. After liquor expansion, the temperature is 40℃, and the reaction time is 120-180 min. The temperature is then raised to 45℃, and the reaction time is 180-240 min. Drainage is then carried out. The acid immersion process is carried out in a rotary drum. Water is added, the liquid ratio is controlled at 0.5-0.6%, the rotation speed is 8-10 rpm, and the internal temperature is 20-22℃. During rotation, 0.5-1.5% formic acid and 0.5-1.5% sulfuric acid diluted with 8-10 times the amount of room temperature water are added through the drum shaft hole, with a pH of 3.5-4.5, and the drum is rotated for 30-60 minutes. The main tanning process is carried out in a rotary drum. Add 2-5% OS and 1-3% LQ-5, rotate for 30 minutes, adjust the pH to 4.0-4.5, and rotate for another 30 minutes. Next, add 10-20% bayberry tannin, rotate for 120-180 minutes. Then add another 10-20% bayberry tannin, rotate for 120-180 minutes. After tanning, add 100% water, adjust the pH to 3.0-3.5, maintain the temperature at 35-45℃, and rotate for 60 minutes. Stop the drum, let it stand overnight, rotate for 30 minutes the next day, drain the water, remove the hides, and let it stand for 3-7 days. The chromium-free retanning process is carried out in a rotary drum. The tanned wet leather is rehydrated using conventional methods, water is added, the liquid-to-leather ratio is controlled at 0.8-1.0, the drum speed is 15 rpm, and the drum internal temperature is 35℃. Modified glutaraldehyde (0.2-2.0%) is added, and the drum is rotated for 30 min. Chromium-free multi-metallic compound tanning agent (0.5-5%) and cationic oil (0.2-2.0%) are added, and the drum is rotated for 90 min. Sodium formate (1%) is added, and the drum is rotated for 30 min. Baking soda (0.3-0.8%) is added, the pH is adjusted to 4.1-4.2, and the drum is rotated for 60 min. Water is added to 100%, the temperature is raised to 40℃, and the drum is rotated for 30 min. The drum is then stopped and left overnight. The next day, the drum is rotated for 30 min, and the water is drained. The neutralization process involves: Wet leather batches are processed using conventional methods, including squeezing out water, slicing, and evenly shaving. The mixture is then placed in a rotating drum, and water is added, maintaining a liquid-to-leather ratio of 1.5, a rotation speed of 15 rpm, and a drum temperature of 35°C. Sodium formate (1%) and PAK-S (1%) are added, and the drum is rotated for 20 minutes. Next, sodium bicarbonate (pre-dissolved in 5 times its volume of water at 35°C) is added to adjust the pH to 4.6-4.8, and the drum is rotated for 60 minutes. Finally, ZY-C (2%) (pre-dispersed evenly in 5 times its volume of water at 55°C) is added, adjusting the pH to 4.6-4.8 and the temperature to 35-38°C, and the drum is rotated for 60 minutes. The filling and dyeing processes are carried out in a rotary drum, with the liquid ratio controlled at 0.5-0.6, the rotation speed at 15 rpm, and the drum internal temperature at 28-35℃. 2% of dispersed tannin™ is added and the drum is rotated for 30 min. Next, 6-18% of filler compounded in different proportions and 2-5% of dye NB are added during rotation, adjusting the pH to 5.0-5.5, and the drum is rotated for 180 min. Then, 0.5% formic acid is added in three portions, rotating for 20 min each time, followed by a 30 min pause. The final pH is 3.8-4.

2. The fatliquoring process is carried out in the same drum and bath as the dyeing process. First, add water at 58-62℃, control the liquid ratio at 1.5-2.0, maintain the drum temperature at 50-55℃, and rotate for 10 minutes. Second, add a fatliquoring emulsion containing 0.6-9.0% synthetic fatliquoring agent SU, 0.3-4.5% beef hoof oil OPE, 0.3-4.5% lecithin BA, 0.3-4.5% lanolin ZBN, and 0.3-4.5% castor oil fatliquoring agent BCA, dispersed and stirred evenly with 5 times the amount of 55℃ hot water, and rotate for 60 minutes. Next, add 150-200% hot water at 48-52℃, add cationic fatliquoring agent GS, and rotate for 60 minutes. Then, add 0.3% formic acid diluted with 10 times the amount of cold water in two portions, and rotate for 20 minutes each time. Finally, check the pH of the bath solution at the endpoint. 3.4-3.6, temperature 50-55℃, finally, wash with 300% hot water at 55℃ for 10 minutes, then drain; The coloring process is carried out in the same drum as the fatliquoring process. Water is added, the bath liquid ratio is controlled at 1.5, the rotation speed is 15 rpm, and the drum internal temperature is 60℃. 1% of chromium-free multimetallic compound tannin is added, and the drum is rotated for 20 min. Next, 0.8-1.5% of dye NB is added, and the drum is rotated for 15 min. 0.8% formic acid diluted with 10 times the amount of cold water is added, and the drum is rotated for 15 min. Next, 0.5% of NB is added, and the drum is rotated for 15 min. 0.8% formic acid diluted with 10 times the amount of cold water is added, and the drum is rotated for 15 min. Finally, 0.3% of AL is added, and the drum is rotated for 20 min. Add 0.5% GS, adjust pH to 3.3-3.6, and run for 15 minutes; wash twice with 200% room temperature water for 10 minutes each time, drain, remove from the drum, and connect the valve. The dewatering and stretching process is carried out on a reciprocating dewatering and stretching machine at a pressure of 30 bar and a feeding speed of 5-25 m / min, resulting in a raw leather moisture content of 50-55%. The drying process involves: first, vacuum drying in a vacuum dryer with the following parameters: temperature 45℃, time 500 s, negative pressure 23-26 Mbar, resulting in a leather moisture content of 23-30%; second, hanging drying on a hanging drying line for 24 hours, resulting in a leather moisture content below 14%; and finally, drying in a constant temperature and humidity oven with the following three stages: oven temperatures of 37℃, 42℃, and 48℃, oven humidity of 33%, drying time of 12 hours, drying time of 6 minutes followed by 10 minutes of dehumidification, resulting in a smooth leather surface and a moisture content of 7-9%. The rewetting and softening process involves first rewetting the dried raw leather, aiming to achieve a moisture content of 28-32% after rewetting. Secondly, the leather is softened using a vibrating softening machine with the following process parameters: conveyor speed 9.5 m / min, 5 stages, resulting in a raw leather moisture content of 28%–32%. Subsequently, it is softened in a stainless steel octagonal tumbling drum with the following process parameters: drum speed 15 r / min, drum temperature 25–30℃, time 6 hours, automatic intermittent forward and reverse rotation, resulting in a raw leather moisture content of 20%–25%. The flattening process involves: first, stretching the leather on a horizontal stretching machine with the following parameters: temperature 60 ℃, stretching distance 6 cm, clamping distance 10-12 cm, and the time for the raw leather to pass through the oven for 20 min, resulting in a moisture content of 14%-18% after processing; second, calendering the leather on a pass-through ironing machine with the following parameters: temperature 120 ℃, pressure 30 kg, and speed 8 m / min, requiring the raw leather to have a clear grain, a smooth feel, and uniform gloss. The coating process is as follows: primer → calendering → polishing → roller polishing → topcoat 1 → roller polishing → topcoat 2 → roller polishing → topcoat → calendering → roller polishing → calendering → softening. The coating is performed on a spraying machine using air spraying, with the following process parameters: pump pressure 3.0 bar, spray gun number 12, atomizing air pressure 5.0 bar, spray gun rotation speed 17-18 r / min, and conveyor belt speed 5-6 m / min. The calendering is performed on a plate ironing machine, with the following process parameters: glossy plate surface temperature 100 ℃, pressure 30 kg, and time 2 s. Polishing is performed on a polishing machine with the following process parameters: feed roller speed 8 m / min, polishing roller speed 8.0 m / min, and the distance between the feed roller and polishing roller 4–5 mm; tumbling is performed on a pass-through ironing machine with the following process parameters: temperature 120 ℃, pressure 30 kg, and speed 8 m / min. The finished leather: The coated raw leather is calendered, softened, trimmed, measured and packaged to obtain the finished leather. The calendering is carried out on a plate ironing machine with the following process parameters: glossy plate surface temperature 100 ℃, pressure 30 kg, time 2 s. The oscillating softening process is carried out in an oscillating softening machine with the following process parameters: conveying speed 9.5 m / min and 5 stages.

2. The high-utilization eco-leather manufacturing process as described in claim 1, characterized in that, The scraps obtained after regularization and the second layer of leather obtained after splitting are used to make leather collagen fiber aggregates or industrial collagen. Method for producing skin collagen fiber aggregates: deliming → softening → acid soaking → drying and slitting → skin collagen fiber aggregates. The deliming, softening, acid soaking, and drying processes can be performed according to the above steps, and the aggregates can be cut into the appropriate specifications as needed. Deashing: The scraps and second layers obtained after regularization and splitting are put into the drum, water is added, the liquid ratio is controlled at 1.5-2.0, the internal temperature is 28-30 ℃, 1.0% surfactant is added, and 0.3% deashing agent TM is added. The drum is rotated for 10-20 minutes, and then rinsed with running water for 10 minutes. Then, 1.2-1.3% deashing agent TM and 0.15% sodium metabisulfite are added, the drum is rotated for 20 minutes, the pH of the bath solution at the end of the deashing process is 8.5-9.0, and then rinsed with running water for 10 minutes. Softening: This process is carried out in the same drum as deashing. First, the deashed scraps and second-layer leather are put into the drum. The liquid ratio is controlled at 1.0-1.2, the rotation speed is 5-6 rpm, and the internal temperature is 32-34 ℃. 0.1-0.3% softening enzyme U5, 0.2% Pingping, and 0.2% ammonium chloride are added. The drum is rotated for 20 min. Then, the drum is rotated for 10 min and stopped for 20 min. This process is repeated 2-4 times. The pH of the bath solution at the end of the softening process is 9.0-9.

2. The solution is then drained. Acid soaking: This is carried out in a softening drum. Water is added, and the liquid ratio is controlled at 0.5-0.6%. The rotation speed is 8-10 rpm, and the internal temperature is 20-22℃. 5-10% sodium chloride is added, and the drum is rotated for 10 minutes. During rotation, 0.5-1.5% formic acid and 0.5-1.5% sulfuric acid diluted with 8-10 times room temperature water are added through the drum shaft hole, with a pH of 3.5-4.

5. The drum is rotated for 30-60 minutes. Drain the water. Hang the leather to air dry, freeze-dry and store. Cut the leather collagen aggregates as required. Further extraction of industrial collagen: Place the above-mentioned skin collagen aggregates into a rotating drum, add ice water, control the liquid-to-liquid ratio at 2.5-3.5, add 0.8-1.5% salt, and rotate for 90-180 minutes until the skin collagen aggregates are uniformly colored, semi-transparent, and slightly swollen. Drain the water; add 0.5 M acetic acid solution at a liquid-to-liquid ratio of 3-30, adjust the pH to 2-2.5, and soak for 90-180 minutes until transparent; continue adding 50-500% of 0.5 M acetic acid solution, stirring thoroughly; add NaOH solution dropwise until the pH is neutral; add 1.5 mol / L NaCl, and salt out for 24 hours to obtain a white flocculent substance; add water, control the liquid-to-liquid ratio at 2-5, and adjust the solution temperature to 45-55℃ and pH... Add 6-8 pieces of papain and hydrolyze for 300-480 minutes. Then heat to 95-100℃ and rotate for 10 minutes. Take the filtrate and spray dry or freeze dry to obtain collagen.

3. The high-utilization eco-leather manufacturing process as described in claim 1, characterized in that, The compound filler ratio in the filling and dyeing process is as follows: 0.5% of protein filler DESOATEN FB, 3.57% of synthetic tanning agent Basyntan® HL, 3.95% of synthetic resin TRUPOTAN® HB, and 0.98% of vegetable tanning agent UNITAN ATO.

4. The high-utilization eco-leather manufacturing process as described in claim 1, characterized in that, The primer formulation in the coating process is as follows: 100 parts water; 25-35 parts waterborne polyurethane; 20-30 parts waterborne casein; 15-30 parts oil emulsion; 6-10 parts wax emulsion; 10-20 parts pigment paste; the primer is applied once, with a coating amount of 10 g / SF.

5. The high-utilization eco-leather manufacturing process as described in claim 1, characterized in that, The topcoat formulation in the coating process is as follows: 100 parts water; 50-80 parts water-based acrylic resin; 5-10 parts oil emulsion; 5-10 parts wax emulsion; 5-10 parts graphene-modified water-based organosilicon; the topcoat is applied twice, with a total coating weight of 15 g / SF.

6. The high-utilization eco-leather manufacturing process as described in claim 1, characterized in that, The topcoat formulation in the coating process is: 100 parts water; 10-30 parts graphene-modified waterborne organosilicon. Apply one topcoat with a coating weight of 8 g / SF.

7. The high-utilization eco-leather manufacturing process as described in claim 6, characterized in that, The graphene-modified waterborne organosilicon formulation is prepared by: dispersing 10-20 parts of graphene oxide dispersion, 20-40 parts of γ-aminopropyltriethoxysilane, 30-60 parts of triethylamine, and 3-5 parts of glycerol under ultrasonication until uniform dispersion is achieved, and then dispersing it with 10-20 parts of organosilicon feel agent under ultrasonication to obtain graphene-modified waterborne organosilicon dispersion.

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