Preparation method of water-washing-resistant high mercerized suede cow leather

Abstract

The application relates to a preparation method of a water-washing-resistant high-scray reverse suede cow leather, which takes a uniform blue wet leather as raw material, sequentially completes a wetting, re-tanning, neutralizing, dyeing and fat-liquoring process, and then carries out subsequent drying finishing sections of water squeezing and stretching, vacuum drying, hanging drying, oscillation softening and leather grinding, and adds a color matching treatment after the leather grinding; the water proportion, the types and dosages of chemical raw materials, the temperature, the drum rotation time and the bath pH value of each process are accurately limited. The high-color-fastness water-washing-resistant dye is selected, the dye can form a stable chemical bond with the leather fiber, the water-washing color fastness is greatly improved, the problems of discoloration after multiple water washing and multi-material staining are eliminated; a plurality of special fat-liquoring agents are matched throughout the process, especially a high-scray suede fat-liquoring agent is introduced in the color matching process, the oil uniformly covers the fiber bundle, the finished product has fine and smooth suede, has a long-lasting soft and silky light wax luster, and can have excellent air permeability without a surface sealing coating.

Description

Technical Field

[0001] This invention relates to the field of leather manufacturing technology, and in particular to a method for preparing water-resistant, high-gloss suede cowhide. Background Technology

[0002] Suede leather, with its unique napped texture, soft feel, and excellent breathability, is widely used in footwear, bags, clothing, and home furnishings. As consumers' demands for leather product quality continue to rise, the market is placing higher requirements on suede leather in terms of washability, appearance, and environmental friendliness. However, existing suede leather products still have significant technical shortcomings in these areas. First, traditional suede leather has poor washability, easily shrinking and deforming when wet. The leather fibers undergo irreversible shrinkage under the influence of water, resulting in poor dimensional stability of the finished product. Simultaneously, after washing, fatliquoring agents and dyes in the leather easily migrate and are lost, causing the leather to harden and thicken, resulting in a rough feel. Dark-colored parts can also easily stain light-colored parts, causing color bleeding.

[0003] The aforementioned defects make traditional suede leather products unsuitable for daily cleaning and care, significantly limiting their application. Secondly, to achieve a high-gloss finish, current technologies typically involve coating the leather surface with mercerizing softeners, resins, and other chemical materials. While this method can improve gloss to some extent, the surface coating is not firmly bonded to the leather fibers and easily peels off after friction or washing, making it difficult to maintain the mercerizing effect. Simultaneously, surface coating treatments clog the leather's natural pores, affecting breathability and natural feel, thus reducing wearing comfort. Furthermore, the retanning process in current leather tanning processes uses large amounts of heavy metal chromium tanning agents, and the discharge of chromium-containing wastewater causes serious environmental pollution. With increasingly stringent environmental regulations, traditional chrome tanning processes are facing increasing pressure.

[0004] In response to the above problems, some studies have attempted to improve the water resistance of suede. However, existing technologies still have the following shortcomings: the water resistance of the products still needs to be further improved, and shrinkage and hardening are still difficult to avoid after multiple washes; while achieving water resistance, a high gloss effect has not been achieved, and the appearance quality of the products cannot meet the needs of the high-end market; although some processes have been improved in terms of environmental protection, the overall process route is still relatively complex.

[0005] Therefore, developing a type of suede cowhide that combines excellent water resistance, long-lasting high silkiness, and good environmental friendliness, as well as its preparation method, has become an urgent technical problem to be solved. Summary of the Invention

[0006] This invention provides a method for preparing water-resistant, high-silky suede cowhide, to overcome the aforementioned problems of existing suede.

[0007] The present invention adopts the following technical solution: A method for preparing water-resistant, high-gloss suede cowhide includes the following process steps: Rehydration: Place the evenly treated wet blue leather into a drum, add 200%-300% water, 1.0%-3.0% oxalic acid, 0.3%-0.6% red-brown soft leather fatliquoring agent, and 0.2%-0.4% oil stabilizer (BORRON SAF, Qingdao Derui Leather Chemical Co., Ltd.) to the drum, maintain the temperature at 45℃, rotate for 90-150 minutes, adjust the pH of the bath solution to ≈2.6, drain the solution, and wash with water; Retanning: Add 90%-150% water to the drum, add 1.0%-2.0% modified light-resistant aldehyde tanning agent (NOVALTAN PF, Sima Chemical (Hong Kong) Co., Ltd.), temperature 33℃, rotate for 25-40 min, add 5.0%-8.0% chromium powder, 2.0%-3.5% acidic phenolic synthetic tannin (Shengtandan JR-309, Zhejiang Shenghui Chemical Co., Ltd.), 1.0%-1.5% reddish-brown soft leather fatliquoring agent, rotate for 45-65 min, add 1.5%-2.0% substitute tanning agent (BESTAN WG 60, Haining Baisiteng Trading Co., Ltd.), rotate for 25-30 min, add 1%-1.3% sodium formate, 0.5%-0.7% baking soda, rotate for 25-30 min, adjust the pH of the bath to ≈3.7, and drain the liquid; Neutralization: Add 100%-150% water to the drum, neutralize 1.5%-3% tannin (TANMATE NSL, Fujian Bates Chemical Industry Co., Ltd.), maintain a temperature of 33℃, and rotate for 20-25 minutes. Add 2.0%-3.0% ammonium bicarbonate (food additive, Shandong Zhongke Green Carbon Technology Co., Ltd.), and rotate for 30-40 minutes. Add 1.5%-3% light yellow leather fatliquoring agent (HZOIL 217, Shandong Haozun Biotechnology Co., Ltd., the same below), and rotate for 50-80 minutes. Adjust the pH of the bath solution to approximately 5.4, drain the solution, and wash with water. Dyeing and fatliquoring: Add 50%-100% water, 1.5%-3.0% resin retanning agent (Leaninggan R8340, Shandong Lining Technology New Material Co., Ltd.), 1.5%-3.0% full-bodied macromolecular acrylic acid (Leaninggan R8090, Shandong Lining Technology New Material Co., Ltd.), and 0.7%-1.5% leather fatliquoring agent (PELLASTOL94S, Sima Chemical (Hong Kong) Co., Ltd., hereinafter the same) to the drum. Maintain a temperature of 33℃ and rotate for 45-100 minutes. Add 3.0%-5.5% acidic phenolic synthetic retanning agent (BLX 14468, Buckman Laboratories Chemicals (Shanghai) Co., Ltd.), 3%-5% synthetic tanning agent (E43, Jiaxing Honglin Leather Chemical Co., Ltd.), and mixed oil fatliquoring agent (DOWELLOR). FS-95 (Sichuan Dawei Technology Co., Ltd.) 3%-5%, lightfast synthetic fatliquoring agent (BITOILCK, Shanghai Tiger Leather Technology Co., Ltd., the same below) 2%-4%, high color fastness washable dye 2%-4%, rotate for 90-180 minutes, add 200%-350% water to the drum, add lightfast synthetic fatliquoring agent 1.0%-2.5%, reddish-brown soft leather fatliquoring agent 2.0%-3.0%, light yellow soft leather fatliquoring agent 2.0%-3.0%, leather fatliquoring agent 1.5%-2%, lecithin fatliquoring agent (DESOPON QL, Sichuan Desai'er New Material Technology Co., Ltd.) 2.0%-4.0%, rotate for 50-120 minutes, add formic acid 3%-4.5% in three portions, rotate for 15-20 minutes, 15-20 minutes, and 15-20 minutes respectively, drain the liquid, and wash out of the drum with water.

[0008] It also includes drying and finishing, which includes the following process steps: squeezing and stretching → vacuum drying → hanging drying → vibrating and softening → leather buffing; Among them: vacuum drying is set at a temperature of 34℃-38℃ for 180s, hanging to dry until the leather moisture content is 13%-14%, and vibration to soften is set at a strength of 5-6 (high strength is set depending on the machine). There are no specific parameters for abrasion. After abrasion, the leather is washed in water.

[0009] It also includes color matching, the specific process of which is as follows: add 200%-300% water, 0.8%-2.0% high color fastness wash-resistant dye, temperature 50℃, rotate for 15-25 minutes, add 0.5%-2.0% formic acid in two batches, rotate for 5-10 minutes and 15-20 minutes respectively, add 2.0%-4.5% high mercerizing suede fatliquoring agent (TRUPON SWS, Tompler Chemical Dyes (Jiaxing) Co., Ltd.), and 1.8%-2.5% synthetic fatliquoring agent (Dermafinish LB liq, Starr International Ltd.), rotate for 30-60 minutes, drain the liquid, wash with water at 33℃ and then exit the drum.

[0010] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following advantages: 1. This invention uses a high color fastness and wash fastness dye for dyeing treatment. The dye forms a strong chemical bond with the leather fiber, effectively inhibiting the desorption and migration of dye molecules during the washing process, thereby significantly improving the wash fastness of the dyed leather and avoiding fading or staining after washing.

[0011] 2. In the fatliquoring process, the present invention adds a high-silky fatliquoring agent, which can evenly penetrate and coat the surface of leather fibers, giving the fibers good lubricity and excellent waxy luster, so that the finished pile presents a delicate, uniform, and long-lasting high-silky visual effect with a silk-like texture.

[0012] 3. In the retanning-neutralization-dyeing and fatliquoring stages, this invention reasonably reduces the proportion of filler and increases the amount of fatliquoring agent accordingly. Through full emulsification and penetration, the oil is evenly distributed between the fiber bundles, thereby significantly improving the softness of the finished leather while ensuring the fullness of the leather body.

[0013] 4. The suede cowhide produced by the technical solution of the present invention has excellent water-washing resistance. After multiple water washes, it remains dimensionally stable, does not deform or harden, and the dye is firmly fixed. There are no color fading or staining problems during the water washing process, and the color fastness grade is significantly improved.

[0014] 5. Due to the use of a high-silky fatliquoring agent for fatliquoring treatment, the resulting cowhide suede has a long-lasting high-silky effect, with fine and even nap, soft and natural luster, and a bright and beautiful appearance. At the same time, it has a soft and waxy feel, and its overall quality is significantly better than similar products.

[0015] 6. The cowhide produced by this invention has high softness, comfortable feel and reliable water resistance, breaking through the application bottleneck of traditional suede cowhide which is difficult to clean and care for. It can be widely used in various fields such as high-end bags, women's boots, clothing and home decorations, and has broad market application prospects.

[0016] 7. In the combined and simultaneous processing of retanning, neutralization, dyeing, and fatliquoring, this invention optimizes the chemical ratios and reaction conditions of each step, ensuring that the chemicals are fully absorbed and combined in the drum. Only three water washes are needed between steps to remove residual chemicals, eliminating the need for repeated washing during the retanning and dyeing stages as in traditional processes. This reduces the total amount of wastewater containing chemicals and the wastewater treatment load, shortens the overall process time, and lowers the power consumption of the drum operation. Detailed Implementation

[0017] To better understand the above technical solution, the following will provide a detailed explanation of the above technical solution in conjunction with the instruction manual and specific implementation methods (the amount of chemicals used in the rewetting, retanning, neutralization, dyeing and fatliquoring and coloring processes are all based on the weight of the wet blue leather after even cutting. For example, if the wet blue leather weighs 100kg after even cutting, then 300% water is 300kg of water). Example 1: A method for preparing water-resistant, high-gloss suede cowhide includes the following process steps: Rewetting: Place the evenly treated wet blue leather into a rotating drum, add 200% water, 1.0% oxalic acid, 0.3% red-brown soft leather fatliquoring agent (TRUPON OSL, Tompler Chemical Dyes (Jiaxing) Co., Ltd., the same below), and 0.2% oil stabilizer (BORRON SAF, Qingdao Derui Leather Co., Ltd.) to the drum, set the temperature to 45℃, rotate for 90 minutes, adjust the pH of the bath solution to ≈2.6, drain the solution, and wash with water; Retanning: Add 90%-150% water to the drum, add 1.0% modified light-resistant aldehyde tanning agent (NOVALTAN PF, Sima Chemical (Hong Kong) Co., Ltd.), temperature 33℃, rotate for 25 minutes, add 5.0% chromium powder, 2.0% acidic phenolic synthetic tannin (Shengtandan JR-309, Zhejiang Shenghui Chemical Co., Ltd.), 1.0% reddish-brown soft leather fatliquoring agent, rotate for 45 minutes, add 1.5% substitute tanning agent (BESTAN WG 60, Haining Baisiteng Trading Co., Ltd.), rotate for 25 minutes, add 1% sodium formate, 0.5% baking soda, rotate for 25 minutes, adjust the pH of the bath to ≈3.7, and drain the liquid; Neutralization: Add 100% water to the drum, neutralize 1.5% tannin (TANMATE NSL, Fujian Bates Chemical Industry Co., Ltd.), maintain temperature at 33℃, rotate for 20 minutes, add 2.0% ammonium bicarbonate (food additive, Shandong Zhongke Green Carbon Technology Co., Ltd.), rotate for 30-40 minutes, add 1.5% light yellow soft leather fatliquoring agent (HZOIL 217, Shandong Haozun Biotechnology Co., Ltd., the same below), rotate for 50 minutes, adjust the pH of the bath solution to approximately 5.4, drain the solution, and wash with water; Dyeing and fatliquoring: Add 50% water, 1.5% resin retanning agent (Leaninggan R8340, Shandong Lining Technology New Material Co., Ltd.), 1.5% full-bodied macromolecular acrylic acid (Leaninggan R8090, Shandong Lining Technology New Material Co., Ltd.), and 0.7% leather fatliquoring agent (PELLASTOL 94S, Sima Chemical (Hong Kong) Co., Ltd., hereinafter the same) to the drum. Maintain a temperature of 33℃ and rotate for 45 minutes. Then add 3.0% acidic phenolic synthetic retanning agent (BLX 14468, Buckman Laboratories Chemical (Shanghai) Co., Ltd.), 3% synthetic tanning agent (E43, Jiaxing Honglin Leather Chemical Co., Ltd.), 3% mixed oil fatliquoring agent (DOWELLOR FS-95, Sichuan Dawei Technology Co., Ltd.), and 3% light-resistant synthetic fatliquoring agent (BITOIL). CK (Shanghai Tiger Leather Technology Co., Ltd., the same below) 2%, high color fastness and wash-resistant dye 2%, rotate for 90-180 minutes, add 200% water to the drum, add 1.0% light-resistant synthetic fatliquoring agent, 2.0% red-brown soft leather fatliquoring agent, 2.0% light-yellow soft leather fatliquoring agent, 1.5% leather fatliquoring agent, 2.0% lecithin fatliquoring agent (DESOPON QL, Sichuan Desaier New Material Technology Co., Ltd.), rotate for 50-120 minutes, add 3% formic acid in three portions, rotate for 15 minutes, 18 minutes and 20 minutes respectively, drain the liquid, and wash out of the drum with water.

[0018] It also includes drying and finishing, which includes the following process steps: squeezing and stretching → vacuum drying → hanging drying → vibrating and softening → leather buffing; Among them: vacuum drying is set at a temperature of 34℃ for 180 seconds, hanging to dry until the leather moisture content is 13%, and vibration to soften is set at a strength of 5-6 (high strength is set depending on the machine). There are no specific parameters for buffing. After buffing, the leather is washed with water in a drum.

[0019] It also includes color matching, and the specific process for color matching is as follows: add 200% water, 0.8% high color fastness and wash-resistant dye, temperature 50℃, rotate for 15 minutes, add 0.5% formic acid in two batches, rotate for 5 minutes and 15 minutes respectively, add 2.0% high mercerizing suede fatliquoring agent (TRUPON SWS, Tompler Chemical Dyes (Jiaxing) Co., Ltd.), and 1.8% synthetic fatliquoring agent (Dermafinish LB liq, Starr International Ltd.), rotate for 30 minutes, drain the liquid, wash with water at 33℃ and then exit the drum.

[0020] Example 2: A method for preparing water-resistant, high-silky suede cowhide includes the following process steps: Rewetting: Place the evenly treated wet blue leather into a rotating drum, add 300% water, 3.0% oxalic acid, 0.6% red-brown soft leather fatliquoring agent (TRUPON OSL, Tompler Chemical Dyes (Jiaxing) Co., Ltd., the same below), and 0.4% oil stabilizer (BORRON SAF, Qingdao Derui Leather Co., Ltd.) to the drum, set the temperature to 45℃, rotate for 150 min, adjust the pH of the bath solution to ≈2.6, drain the solution, and wash with water; Retanning: Add 150% water to the drum, add 2.0% modified light-resistant aldehyde tanning agent (NOVALTAN PF, Sima Chemical (Hong Kong) Co., Ltd.), temperature 33℃, rotate for 40 min, add 8.0% chromium powder, 2.0%-3.5% acidic phenolic synthetic tannin (Shengtandan JR-309, Zhejiang Shenghui Chemical Co., Ltd.), 1.5% reddish-brown soft leather fatliquoring agent, rotate for 65 min, add 2.0% alternative tanning agent (BESTAN WG 60, Haining Baisiteng Trading Co., Ltd.), rotate for 30 min, add 1.3% sodium formate, 0.7% baking soda, rotate for 30 min, adjust the pH of the bath to ≈3.7, and drain the liquid; Neutralization: Add 150% water to the drum, add 3% neutralizing tannin (TANMATE NSL, Fujian Bates Chemical Industry Co., Ltd.), maintain the temperature at 33℃, and rotate for 25 minutes. Add 3.0% ammonium bicarbonate (food additive, Shandong Zhongke Green Carbon Technology Co., Ltd.), and rotate for 40 minutes. Add 3% light yellow soft leather fatliquoring agent (HZOIL 217, Shandong Haozun Biotechnology Co., Ltd., the same below), and rotate for 80 minutes. Adjust the pH of the bath solution to approximately 5.4, drain the solution, and wash with water. Dyeing and fatliquoring: Add 100% water, 3.0% resin retanning agent (Leaninggan R8340, Shandong Lining Technology New Material Co., Ltd.), 3.0% full-bodied macromolecular acrylic acid (Leaninggan R8090, Shandong Lining Technology New Material Co., Ltd.), and 1.5% leather fatliquoring agent (PELLASTOL 94S, Sima Chemical (Hong Kong) Co., Ltd., hereinafter the same) to the drum. Maintain a temperature of 33℃ and rotate for 100 minutes. Then add 5.5% acidic phenolic synthetic retanning agent (BLX 14468, Buckman Laboratories Chemical (Shanghai) Co., Ltd.), 5% synthetic tanning agent (E43, Jiaxing Honglin Leather Chemical Co., Ltd.), 5% mixed oil fatliquoring agent (DOWELLOR FS-95, Sichuan Dawei Technology Co., Ltd.), and 5% light-resistant synthetic fatliquoring agent (BITOIL). CK (Shanghai Tiger Leather Technology Co., Ltd., the same below) 4%, high color fastness and wash-resistant dye 4%, rotate for 180 min, add 350% water to the drum, add 2.5% light fastness synthetic fatliquoring agent, 3.0% red-brown soft leather fatliquoring agent, 3.0% light yellow soft leather fatliquoring agent, 2% leather fatliquoring agent, 4.0% lecithin fatliquoring agent (DESOPON QL, Sichuan Desaier New Material Technology Co., Ltd.), rotate for 120 min, add 4.5% formic acid in three portions, rotate for 15 min, 18 min and 20 min respectively, drain the liquid, and wash out of the drum with water.

[0021] It also includes drying and finishing, which includes the following process steps: squeezing and stretching → vacuum drying → hanging drying → vibrating and softening → leather buffing; Among them: vacuum drying is set at 38℃ for 180s, hanging to dry until the leather moisture content is 14%, and vibration to soften is set at a strength of 5-6 (high strength is set depending on the machine). There are no specific parameters for buffing. After buffing, the leather is washed with water in a drum.

[0022] It also includes color matching, and the specific process for color matching is as follows: add 300% water, 2.0% high color fastness wash-resistant dye, temperature 50℃, rotate for 25 minutes, add 2.0% formic acid in two batches, rotate for 10 minutes and 20 minutes respectively, add 4.5% high mercerizing suede fatliquoring agent (TRUPON SWS, Tompler Chemical Dyes (Jiaxing) Co., Ltd.), and 2.5% synthetic fatliquoring agent (Dermafinish LBliq, Starr International Ltd.), rotate for 60 minutes, drain the liquid, wash with water at 33℃ and then exit the drum.

[0023] The suede cowhide obtained in this embodiment was tested, as follows: Results of colorfastness tests for household and commercial washing 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 method for preparing water-resistant, high-gloss suede cowhide, characterized in that, The process includes the following steps: Rehydration: Place the evenly treated wet blue leather into a drum, add 200%-300% water, 1.0%-3.0% oxalic acid, 0.3%-0.6% red-brown soft leather fatliquoring agent, and 0.2%-0.4% oil stabilizer to the drum, maintain the temperature at 45℃, rotate for 90-150 minutes, adjust the pH of the bath solution to ≈2.6, drain the solution, and wash with water; Retanning: Add 90%-150% water to the drum, add 1.0%-2.0% modified light-resistant aldehyde tanning agent, maintain temperature at 33℃, rotate for 25-40 min, add 5.0%-8.0% chromium powder, 2.0%-3.5% acidic phenolic synthetic tannin, 1.0%-1.5% reddish-brown soft leather fatliquoring agent, rotate for 45-65 min, add 1.5%-2.0% substitute tanning agent, rotate for 25-30 min, add 1%-1.3% sodium formate, 0.5%-0.7% baking soda, rotate for 25-30 min, adjust the pH of the bath to ≈3.7, and drain the liquid; Neutralization: Add 100%-150% water to the drum to neutralize 1.5%-3% tannins. Maintain a temperature of 33℃ and rotate for 20-25 minutes. Add 2.0%-3.0% ammonium bicarbonate and rotate for 30-40 minutes. Add 1.5%-3% light yellow leather fatliquoring agent and rotate for 50-80 minutes. Adjust the pH of the bath solution to approximately 5.

4. Drain the solution and rinse with water. Dyeing and fatliquoring: Add 50%-100% water, 1.5%-3.0% resin retanning agent, 1.5%-3.0% full-bodied macromolecular acrylic acid, and 0.7%-1.5% leather fatliquoring agent to the drum. Maintain a temperature of 33℃ and rotate for 45-100 minutes. Then add 3.0%-5.5% acidic phenolic synthetic retanning agent, 3%-5% synthetic tanning agent, 3%-5% mixed oil fatliquoring agent, 2%-4% lightfast synthetic fatliquoring agent, and 2%-4% high colorfastness wash-resistant dye. Rotate for 90-180 minutes. Add 200%-350% water to the drum, then add 1.0%-2.5% lightfast synthetic fatliquoring agent, 2.0%-3.0% reddish-brown soft leather fatliquoring agent, 2.0%-3.0% light yellow soft leather fatliquoring agent, 1.5%-2% leather fatliquoring agent, and 2.0%-4.0% lecithin fatliquoring agent. Rotate for 50-120 minutes, then add 3%-4.5% formic acid in three portions, rotating for 15-20 minutes, 15-20 minutes, and 15-20 minutes respectively. Drain the liquid and rinse the drum with water.

2. The method for preparing a water-washable, high-gloss suede cowhide according to claim 1, characterized in that, It also includes drying and finishing, which includes the following process steps: squeezing and stretching → vacuum drying → hanging drying → vibrating and softening → leather buffing; Among them: vacuum drying is set at a temperature of 34℃-38℃ for 180s, hanging to dry until the leather moisture content is 13%-14%, and vibration to soften is at a strength of 5-6. There are no specific parameters for buffing. After buffing, the leather is washed in a drum.

3. The method for preparing a water-washable, high-gloss suede cowhide according to claim 2, characterized in that, It also includes color matching, and the specific process for color matching is as follows: add 200%-300% water, 0.8%-2.0% high color fastness washable dye, temperature 50℃, rotate for 15-25 minutes, add 0.5%-2.0% formic acid in two batches, rotate for 5-10 minutes and 15-20 minutes respectively, add 2.0%-4.5% high mercerization suede fatliquoring agent, 1.8%-2.5% synthetic fatliquoring agent, rotate for 30-60 minutes, drain the liquid, wash with water at 33℃ and then exit the drum.

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