Chrome-free tanning leather production method and system

Abstract

The invention relates to a chrome-free tanning leather production method and system, and the method comprises the following steps: S1, grouping raw leather, and carrying out pre-soaking, fleshing, main soaking, liming, leather splitting, deliming and softening treatment to produce bare leather; s2, pH adjustment, salt-free and pickling-free Tara tanning, zeolite tanning and standing are conducted on the bare skin, and tanned white skin is produced; s3, wringing, shaving, washing, neutralizing, filling and retanning, filling, dyeing, fat liquoring and fixing are conducted on the tanned white leather, and wet leather is produced; s4, the wet leather is subjected to wringing stretching, vacuum drying, hanging airing and humidifying drying, and dry leather is produced; and S5, the dry leather is subjected to standing, water returning, standing, water returning, standing, vibration staking, crust milling, dry toggling flattening and transfer coating, and finished leather is produced. The method has the beneficial effects that the tara tanning material and the zeolite tanning agent are used for salt-free and pickling-free combined tanning, traditional chrome tanning is replaced, a chrome-free and formaldehyde-free process is achieved, the finished leather has the fullness of vegetable tanning leather and the flexibility and elasticity of chrome tanning leather, and the wet heat stability is closer to the high-quality application performance such as chrome tanning leather.

Description

Technical Field

[0001] This invention relates to the field of leather manufacturing technology, and specifically to a method and system for producing chromium-free tanned leather. Background Technology

[0002] Leather is a natural material made from animal hides through physical and chemical processing. It possesses a certain strength, flexibility, and durability. Its unique fiber structure and properties make it widely used in clothing, bags, furniture, automobiles, and other fields.

[0003] In existing technologies, traditional leather tanning mainly uses chromium salt tanning agents, which leads to heavy metal pollution and health risks. Traditional aldehyde tanning has a shrinkage temperature of 75°C, which is relatively low. It also has poor wet heat stability and problems such as low tanning efficiency and poor tensile strength. Summary of the Invention

[0004] To address the shortcomings of existing technologies, this application proposes a chromium-free tanned leather production method and system. It uses Tara tanning agent and zeolite tanning agent for salt-free and acid-free tanning, replacing traditional chromium tanning, and achieving a chromium-free and formaldehyde-free process. The finished leather combines the fullness of vegetable-tanned leather with the softness and elasticity of chromium-tanned leather, and its wet heat stability is closer to that of chromium-tanned leather and other high-quality application properties.

[0005] The following is the technical solution of the present invention: a method for producing chromium-free tanned leather, comprising the following steps: S1. Raw hides are batched and processed through pre-soaking, de-fleshing, main soaking, liming, peeling, deliming and softening to produce bare hides; S2. The raw hides are subjected to pH adjustment, salt-free and acid-free Tara tanning, zeolite tanning, and settling to produce tanned white hides; S3. The tanned white leather is squeezed, shaved evenly, washed, neutralized, filled and retanned, filled, dyed, fatliquored and fixed to produce wet leather. S4. The wet leather is squeezed out of water, stretched, vacuum dried, hung to dry, and conditioned to produce dry leather. S5. The dry leather is subjected to a series of processes including resting, rehydration, resting, rehydration, resting, vibration to soften, tumbling to soften, stretching on a dry board to flatten, and then coating to produce finished leather.

[0006] As a preferred embodiment of the present invention, in S1, the rotation speed of the drums for pre-soaking, main soaking, ash soaking, deashing and softening is 7-9 rpm, and the sheet thickness is 2.0-2.2 mm.

[0007] As a preferred embodiment of the present invention, in S2, the rotation speed of the drum for pH adjustment, salt-free and acid-free Tara tanning and zeolite tanning is 6-8 rpm, Tara tanning uses Tara tanning material, and zeolite tanning uses zeolite tanning agent.

[0008] As a preferred embodiment of the present invention, in S3, the rotation speed of the drum for washing, neutralizing, retanning, dyeing, and fatliquoring is 10-12 rpm, the water squeezing pressure is 3.5-4.5 MPa, and the uniform thickness is 1.1-1.15 mm.

[0009] As a preferred embodiment of the present invention, in S4, the water-squeezing and stretching pressure is 2-3 MPa, the vacuum drying temperature is 40-45°C, the drying time is 90-120 seconds, and the humidification drying temperature is 40-45°C.

[0010] As a preferred embodiment of the present invention, in S5, the rehydration parameter is 8g / sf, the softening time of the leather is 6-8 hours, and the temperature for dry stretching and flattening is 44-46°C.

[0011] As a preferred embodiment of the present invention, in S5, the shrinkage temperature of the finished leather is ≥90°C.

[0012] A chromium-free tanning leather production system, comprising: The raw material processing module is used to clean and pre-treat raw hides to produce bare hides; The tanning module is used to achieve salt-free, acid-free, and chromium-free tanning to produce tanned white leather, and is connected to the raw material processing module; The retanning and dyeing module is used to retan, dye, and fatliquore tanned white leather to produce wet leather, and is connected to the tanning module; The drying module is used to squeeze water out of wet leather, stretch it, vacuum dry it, hang it to air dry it, and adjust the humidity to produce dry leather. It is connected to the retanning and dyeing module. The finishing module is used for final processing to improve the feel of the leather and produce finished leather products; it is connected to the drying module. The conveying module is used to ensure the automatic transfer of leather between modules, connecting the raw material processing module, tanning module, retanning and dyeing module, drying module, and finishing module.

[0013] As a preferred embodiment of the present invention, the raw material processing module includes a batching device, a pre-soaking drum, a meat removal machine, a main soaking drum, a liming drum, a skin splitting machine, a deliming drum, and a softening drum; the tanning module includes a pH adjusting drum, a Tara tanning drum, a zeolite tanning drum, and a settling tray; the retanning and dyeing module includes a water squeezing machine, a leveling machine, a washing drum, a neutralizing drum, a retanning drum, a dyeing drum, a fatliquoring drum, and a fixing drum; the drying module includes a water squeezing and stretching machine, a vacuum dryer, a hanging drying box, and a humidity-regulating drying line; and the finishing module includes a settling device, a rehumidifier, a vibrating softening machine, a dry drum, a stretching dryer, and a coating device.

[0014] As a preferred embodiment of the present invention, the conveying module includes a belt conveyor and a pneumatic push rod.

[0015] The beneficial effects of this invention are: the use of Tara tanning material and zeolite tanning agent for salt-free and acid-free combined tanning replaces traditional chrome tanning, achieving a chrome-free and formaldehyde-free process that meets ZDHC and low-carbon standards; the product has superior performance, with a shrinkage temperature Ts≥90°C, tensile strength≥200N / 20mm, folding strength without cracks, and strong applicability. Attached Figure Description

[0016] Figure 1 This is a schematic diagram of the system of the present invention. Figure 1 ; Figure 2 This is a schematic diagram of the system of the present invention. Figure 2 ; Figure 3 This is a diagram illustrating the steps of the method of the present invention; Figure 4 This is a flowchart of the method of the present invention; In the diagram: 1. Raw material processing module; 101. Batching device; 102. Pre-soaking drum; 103. Meat remover; 104. Main soaking drum; 105. Liming drum; 106. Slicing machine; 107. Deliming drum; 108. Softening drum; 2. Tanning module; 201. pH adjustment drum; 202. Tara tanning drum; 203. Zeolite tanning drum; 204. Settling tray; 3. Retanning and dyeing module; 301. Dewatering machine; 302. Leveling machine; 303. Washing drum; 304. Neutralization 305. Retanning drum; 306. Dyeing drum; 307. Fat-adding drum; 308. Fixed drum; 4. Drying module; 401. Dewatering and stretching machine; 402. Vacuum dryer; 403. Hanging drying box; 404. Humidity conditioning and drying line; 5. Finishing module; 501. Settling device; 502. Rehumidifier; 503. Vibrating softening machine; 504. Dry drum; 505. Stretching board dryer; 506. Coating equipment; 6. Conveying module; 601. Belt conveyor; 602. Pneumatic push rod. Detailed Implementation

[0017] To make the technical problems solved by the present invention, the technical solutions adopted, and the technical effects achieved clearer, the technical solutions of the embodiments of the present invention will be further described in detail below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0018] Example 1 like Figure 1 and Figure 2 As shown, a chrome-free tanning leather production system includes: Raw material processing module 1 is used to clean and pre-process raw hides to produce bare hides; Tanning module 2 is used to achieve salt-free, acid-free, and chromium-free tanning to produce tanned white leather, and is connected to raw material processing module 1; The retanning and dyeing module 3 is used to retan, dye, and fatliquoring tanned white leather to produce wet leather, and is connected to the tanning module 2; Drying module 4 is used to squeeze water, stretch, vacuum dry, hang and dry, and adjust humidity to produce dry leather from wet leather, and is connected to retanning and dyeing module 3; Finishing module 5 is used for final processing to improve the feel of the leather and produce finished leather, and is connected to drying module 4; The conveying module 6 is used to ensure the automatic transfer of leather between modules, connecting the raw material processing module 1, tanning module 2, retanning and dyeing module 3, drying module 4 and finishing module 5.

[0019] In this embodiment, the raw material processing module 1 is used to clean and pre-treat the raw hides, removing impurities and producing bare hides. The raw material processing module 1 includes a batching device 101, a pre-soaking drum 102, a meating machine 103, a main soaking drum 104, a liming drum 105, a skin-slicing machine 106, a deliming drum 107, and a softening drum 108. The batching device 101 is connected to the inlet of the pre-soaking drum 102, the outlet of the pre-soaking drum 102 is connected to the meating machine 103, the outlet of the meating machine 103 is connected to the main soaking drum 104, and so on until the outlet of the softening drum 108. The batching device 101 achieves matching of coat color and size; the drums promote soaking and deliming through mechanical stirring; the meating machine 103 is used for scraping oil off the reverse side; and the skin-slicing machine 106 controls the thickness in preparation for tanning.

[0020] After being sorted by the batching device 101, the raw hides are fed into the pre-soaking drum 102. After pre-soaking to remove impurities, they are output to the meating machine 103. After meating, they are output to the main soaking drum 104. They are processed in sequence, and finally the softening drum 108 produces the naked hides, which are then output to the tanning module 2.

[0021] All drums rotate at 8 revolutions per minute; the thickness of the skin slices produced by the skin-slicing machine 106 is 2.0-2.2 mm.

[0022] In this embodiment, the tanning module 2 is used to achieve chromium-free tanning to produce tanned hides. The tanning module 2 is connected to the outlet of the raw material processing module 1. The tanning module 2 includes a pH adjusting drum 201, a Tara tanning drum 202, a zeolite tanning drum 203, and a settling tray 204. The pH adjusting drum 201 receives raw hides at its inlet and is connected to the Tara tanning drum 202 at its outlet. The outlet of the Tara tanning drum 202 is connected to the zeolite tanning drum 203, and the outlet of the zeolite tanning drum 203 is connected to the settling tray 204. All drums are lined with an anti-rust coating to prevent rust contamination. The pH adjusting drum 201 is used to adjust the pH value of the raw leather. The Tara tanning drum 202 uses Tara tanning agent for preliminary tanning. The zeolite tanning drum 203 combines zeolite tanning agent to enhance the bonding force. The settling tray 204 promotes the penetration of tanning agent and produces tanned white leather with a shrinkage temperature ≥80°C. The shrinkage temperature of the finished leather is ≥90°C. Compared with the 75°C shrinkage temperature of traditional aldehyde tanning, the shrinkage temperature is higher, the wet heat stability is improved, and the weather resistance is improved. It can avoid the shrinkage and deformation problems that occur during the ironing and shaping process of chrome-free tanned leather seats.

[0023] After being treated by pH-adjusting drum 201, the raw hides are output to Tara tanning drum 202, then to zeolite tanning drum 203, and finally to settling tray 204. After settling, the tanned hides are output to retanning and dyeing module 3.

[0024] The drum rotates at 6-8 revolutions per minute, with the larger the diameter, the lower the rotation speed; the stationary tray is made of 204 stainless steel and is laid flat with leather.

[0025] In this embodiment, the retanning and dyeing module 3 is used to retann, dye, and fatliquoring tanned leather to produce wet leather. The retanning and dyeing module 3 is connected to the outlet of the tanning module 2 and includes a dewatering machine 301, a leveling machine 302, a washing drum 303, a neutralizing drum 304, a retanning drum 305, a dyeing drum 306, a fatliquoring drum 307, and a stationary drum 308. The dewatering machine 301 receives the tanned leather at its inlet and connects to the leveling machine 302 at its outlet. The leveling machine 302's outlet connects to the washing drum 303, and so on, until the stationary drum 308 exits. The dewatering machine 301 dehydrates the leather, the leveling machine 302 precisely controls the thickness, and the drum series completes washing, neutralization, filling, retanning, dyeing, fatliquoring, and fixing, improving the leather's fullness and color fastness. Conventional chromium-free retanning agents are used.

[0026] After being dehydrated by the water-squeezing machine 301, the tanned white leather is output to the leveling machine 302, leveled, and then output to the washing drum 303. After being washed, it is output to the neutralizing drum 304. After being processed in sequence, the wet leather is finally produced by the fixed drum 308 and output to the drying module 4.

[0027] The pressure of the dewatering machine 301 is 3.5-4.5MPa, the shaving thickness of the leveling machine 302 is 1.1-1.15mm, and the rotation speed of the washing drum 303 is 11 revolutions per minute.

[0028] In this embodiment, the drying module 4 is used to perform water squeezing and stretching, vacuum drying, hanging drying, and humidity conditioning drying on wet leather to produce dry leather. The drying module 4 is connected to the outlet of the retanning and dyeing module 3. The drying module 4 includes a water squeezing and stretching machine 401, a vacuum dryer 402, a hanging drying chamber 403, and a humidity conditioning drying line 404. The water squeezing and stretching machine 401 receives wet leather at its inlet and is connected to the vacuum dryer 402 at its outlet. The outlet of the vacuum dryer 402 is connected to the hanging drying chamber 403, and the outlet of the hanging drying chamber 403 is connected to the humidity conditioning drying line 404. The water squeezing and stretching machine 401 flattens the leather, the vacuum dryer 402 dehumidifies at low temperature, the hanging drying chamber 403 dries the leather evenly, and the humidity conditioning drying line 404 controls the humidity to prevent the leather from becoming brittle.

[0029] After being flattened by the water-squeezing and stretching machine 401, the wet leather is output to the vacuum dryer 402. After vacuum drying, it is output to the hanging drying box 403. After hanging drying, it is output to the humidity-conditioning drying line 404. After humidity conditioning, the dry leather is output to the finishing module 5.

[0030] The dewatering stretching machine 401 has a pressure of 2-3 MPa, the vacuum dryer 402 has a temperature of 42°C and a time of 120 seconds, the hanging drying oven 403 is naturally air-dried, and the humidity-regulating drying line 404 has a temperature of 40-45°C.

[0031] In this embodiment, the finishing module 5 is used for final processing to improve the feel of the leather. The finishing module 5 is connected to the outlet of the drying module 4 and includes a settling device 501 (such as a trestle), a rehumidifier 502, a vibrating softening machine 503, a dry drum 504, a stretching dryer 505, and a finishing device 506. The settling device 501 receives the dried leather at its inlet and its outlet is connected to the rehumidifier 502. The outlet of the rehumidifier 502 is connected to the vibrating softening machine 503, and so on, until the outlet of the finishing device 506. The settling device 501 stabilizes the leather, the rehumidifier 502 regulates humidity, the vibrating softening machine 503 and the dry drum 504 enhance softness, the stretching dryer 505 shapes the leather, and the finishing device 506 applies an environmentally friendly coating.

[0032] After being stabilized by the settling device 501, the dried leather is output to the rehumidifier 502. After rehumidification, it is output to the vibrating softening machine 503. After softening, it is output to the dry drum 504. After being tumbled and softened, it is output to the stretching dryer 505. After stretching, it is output to the coating equipment 506 to produce finished leather.

[0033] The rehumidifier 502 has a humidification capacity of 8g / sf, the vibrating softening machine 503 has an intensity of level 4, the dry drum 504 has a drying time of 6-8 hours, and the stretching plate dryer 505 has a temperature of 45°C.

[0034] In this embodiment, all modules are connected via a conveyor module 6, which includes a belt conveyor 601 and a pneumatic pusher 602, ensuring automatic transfer of the leather between modules and avoiding contamination caused by manual intervention. A central control unit (PLC) monitors the parameters of each module, including speed and temperature, to ensure process consistency.

[0035] In a possible embodiment, the conveying module 6 is an industrial robot, which transfers the leather between the modules.

[0036] It should be understood that the drum functions involved in the raw material processing module 1, tanning module 2, retanning and dyeing module 3, drying module 4 and finishing module 5 of this invention are integrated into a single drum or multiple cooperating drums through functional integration, forming an integrated or modular drum configuration. These technical solutions are all equivalent extensions of the technical concept protected by this application and fall within the protection scope of this invention.

[0037] Example 2 like Figure 3 and Figure 4 As shown, a method for producing chrome-free tanned leather includes the following steps: S1. Raw hides are batched and processed through pre-soaking, de-fleshing, main soaking, liming, peeling, deliming and softening to produce bare hides; S2. The raw hides are subjected to pH adjustment, salt-free and acid-free Tara tanning, zeolite tanning, and settling to produce tanned white hides; S3. The tanned white leather is squeezed, shaved evenly, washed, neutralized, filled and retanned, filled, dyed, fatliquored and fixed to produce wet leather. S4. The wet leather is squeezed out of water, stretched, vacuum dried, hung to dry, and conditioned to produce dry leather. S5. The dry leather is subjected to a series of processes including resting, rehydration, resting, rehydration, resting, vibration to soften, tumbling to soften, stretching on a dry board to flatten, and then coating to produce finished leather.

[0038] In step S1, the batch of raw hides undergoes pre-soaking, fleshing, main soaking, liming, slicing, deliming, and softening treatments to produce bare hides. Specifically, the pre-soaking drum 102 performs pre-soaking at a speed of 8 rpm; the main soaking drum 104 performs main soaking at a speed of 8 rpm; the liming drum 105 performs liming at a speed of 8 rpm; the slicing machine 106 slices the hides to a thickness of 2.0-2.2 mm; the deliming drum 107 performs deliming at a speed of 8 rpm; and the softening drum 108 softens the hides at a speed of 8 rpm.

[0039] In step S2, the bare hides undergo pH adjustment, salt-free and acid-free Tara tanning, zeolite tanning, and settling to produce tanned white hides. Specifically, pH adjustment drum 201 performs pH adjustment at a speed of 6-8 rpm; Tara tanning drum 202 performs Tara tanning at a speed of 6-8 rpm; and zeolite tanning drum 203 performs zeolite tanning at a speed of 6-8 rpm.

[0040] In step S3, the tanned white leather undergoes water squeezing, leveling, washing, neutralization, retanning with filling, filling, dyeing, fatliquoring, and fixing to produce wet leather. Specifically, the water squeezing machine 301 performs water squeezing with a pressure of 3.5-4.5 MPa; the leveling machine 302 performs leveling with a leveling thickness of 1.1-1.15 mm; and the washing drum 303, neutralization drum 304, retanning drum 305, dyeing drum 306, and fatliquoring drum 307 operate at a speed of 11 rpm.

[0041] In step S4, the wet leather undergoes dewatering and stretching, vacuum drying, hanging to air dry, and conditioning drying to produce dry leather. Specifically, the dewatering and stretching machine 401 performs dewatering and stretching at a pressure of 2-3 MPa; the vacuum dryer 402 performs vacuum drying at a temperature of 42°C for 120 seconds; and the conditioning drying line 404 performs conditioning drying at a temperature of 40-45°C.

[0042] In a possible embodiment, the drying temperature of the vacuum dryer 402 is 40-45°C.

[0043] In step S5, the dried leather undergoes a series of processes including settling, rehydration, settling, rehydration, settling, vibrating to soften, tumbling to soften the hide, dry stretching and flattening, and transfer coating to produce finished leather. Specifically, the rehydration machine 502 performs rehydration, with a unit area quantitative rehydration parameter of 8g / sf; the vibrating to softening machine 503 performs vibrating to soften the hide, with a speed setting of 4; the dry drum 504 tumbles to soften the hide for 6-8 hours; and the stretching dryer 505 performs dry stretching and flattening, with a temperature of 45°C.

[0044] Example 3 This embodiment uses the production of automotive interior leather as an example for illustration.

[0045] During system operation, raw hides enter the raw material processing module 1, are batched and processed sequentially to produce bare hides; the tanning module 2 uses 10% Tara tanning agent and 5% zeolite tanning agent by weight of the grey hides, and performs tanning without salt or acid leaching, and allows it to stand for more than 24 hours; subsequent modules operate according to the parameters of Example 2. The central control unit monitors the drum speed and temperature in real time.

[0046] The test results are shown in Table 1.

[0047] Table 1 shows the test results.

[0048] The test results show that the finished leather has a thickness of 1.21mm, a tensile strength of 250.5N / 20mm in the longitudinal direction, a heat aging resistance of level 4, and an odor level of 3.0, meeting the GWTA standard.

[0049] This invention utilizes a combination of Tara tanning agents and zeolite tanning agents for salt-free and acid-free tanning, replacing traditional chrome tanning. This achieves a chrome-free and formaldehyde-free process, meeting ZDHC and low-carbon standards. Test data demonstrates superior performance: the finished leather shrinkage temperature (Ts) is ≥90°C, compared to the 75°C shrinkage temperature of traditional aldehyde tanning. This higher shrinkage temperature improves wet heat stability and weather resistance, preventing shrinkage and deformation issues during ironing and shaping of chrome-free tanned leather seats. The tensile strength is ≥200N / 20mm, and the folding strength is crack-free. The modular system reduces energy consumption and shortens the production cycle.

[0050] Although preferred embodiments of the invention have been described, those skilled in the art, upon learning the basic inventive concept, can make other changes and modifications to these embodiments. Clearly, those skilled in the art can make various alterations and variations to the invention without departing from its spirit and scope. Therefore, if these modifications and variations fall within the scope of equivalents of the invention, the invention is also intended to include these modifications and variations.

Claims

1. A method for producing chromium-free tanned leather, characterized in that, Includes the following steps: S1. Raw hides are batched and processed through pre-soaking, de-fleshing, main soaking, liming, peeling, deliming and softening to produce bare hides; S2. The raw hides are subjected to pH adjustment, salt-free and acid-free Tara tanning, zeolite tanning, and settling to produce tanned white hides; S3. The tanned white leather is squeezed, shaved evenly, washed, neutralized, filled and retanned, filled, dyed, fatliquored and fixed to produce wet leather. S4. The wet leather is squeezed out of water, stretched, vacuum dried, hung to dry, and conditioned to produce dry leather. S5. The dry leather is subjected to a series of processes including resting, rehydration, resting, rehydration, resting, vibration to soften, tumbling to soften, stretching on a dry board to flatten, and then coating to produce finished leather.

2. The method for producing chromium-free tanned leather according to claim 1, characterized in that, In S1, the rotation speed of the drums for pre-soaking, main soaking, ash soaking, deashing, and softening is 7-9 rpm, and the sheet thickness is 2.0-2.2 mm.

3. The method for producing chromium-free tanned leather according to claim 1, characterized in that, In S2, the rotation speed of the drums for pH adjustment, salt-free and acid-free Tara tanning, and zeolite tanning is 6-8 rpm. Tara tanning uses Tara tanning material, and zeolite tanning uses zeolite tanning agent.

4. The method for producing chromium-free tanned leather according to claim 1, characterized in that, In S3, the rotation speed of the drums for washing, neutralizing, retanning, dyeing, and fatliquoring is 10-12 rpm, the water squeezing pressure is 3.5-4.5 MPa, and the uniform thickness is 1.1-1.15 mm.

5. The method for producing chromium-free tanned leather according to claim 1, characterized in that, In S4, the dewatering and stretching pressure is 2-3 MPa, the vacuum drying temperature is 40-45°C, the drying time is 90-120 seconds, and the conditioning drying temperature is 40-45°C.

6. The method for producing chromium-free tanned leather according to claim 1, characterized in that, In S5, the moisture regain parameter is 8g / sf, the softening time of the leather is 6-8 hours, and the temperature for dry stretching and flattening is 44-46°C.

7. The method for producing chromium-free tanned leather according to claim 1, characterized in that, In S5, the shrinkage temperature of the finished leather is ≥90°C.

8. A chromium-free tanning leather production system, applicable to the chromium-free tanning leather production method according to any one of claims 1-7, characterized in that, include: The raw material processing module is used to clean and pre-treat raw hides to produce bare hides; The tanning module is used to achieve salt-free, acid-free, and chromium-free tanning to produce tanned white leather, and is connected to the raw material processing module; The retanning and dyeing module is used to retan, dye, and fatliquore tanned white leather to produce wet leather, and is connected to the tanning module; The drying module is used to squeeze water out of wet leather, stretch it, vacuum dry it, hang it to air dry it, and adjust the humidity to produce dry leather. It is connected to the retanning and dyeing module. The finishing module is used for final processing to improve the feel of the leather and produce finished leather products; it is connected to the drying module. The conveying module is used to ensure the automatic transfer of leather between modules, connecting the raw material processing module, tanning module, retanning and dyeing module, drying module, and finishing module.

9. A chromium-free tanning leather production system according to claim 8, characterized in that, The raw material processing module includes batching equipment, pre-soaking drums, de-meatizing machines, main soaking drums, liming drums, peeling machines, deliming drums, and softening drums. The tanning module includes pH adjusting drums, Tara tanning drums, zeolite tanning drums, and settling trays. The retanning and dyeing module includes a squeezing machine, leveling machine, washing drums, neutralizing drums, retanning drums, dyeing drums, fatliquoring drums, and fixing drums. The drying module includes a squeezing and stretching machine, a vacuum dryer, a hanging drying box, and a humidity-regulating drying line. The finishing module includes a settling device, a rehumidifier, a vibrating softening machine, dry drums, a stretching dryer, and coating equipment.

10. A chromium-free tanning leather production system according to claim 8, characterized in that, The transmission module includes a belt conveyor and a pneumatic push rod.

Images