Environment-friendly water-dyed instep leather production process

Abstract

The invention relates to a production process of environment-friendly water-dyed instep leather. The process comprises the following steps of: pickling naked leather, tanning, neutralizing, wringing, shaving, retanning, neutralizing, dyeing, oiling, combined tanning, washing, blowing, and finishing in a dry state to obtain a finished product. No chrome tanning agent or chrome-containing tanning agent is used in the whole process of the technology, no chrome-containing waste water, sludge or solid waste is generated, the hidden danger of heavy metal pollution is eliminated from the source, the environmental protection treatment cost is saved, and the technology conforms to the trend of developing ecological leather.

Description

Technical Field

[0001] The invention relates to the technical field of leather manufacturing, in particular to an environmentally friendly water-dyed shoe upper leather production process. Background Art

[0002] Tanning is a key process in the leather industry. During the tanning process, the collagen fibers of the skin are combined with the tanning agent, and the properties are fundamentally changed, turning the skin into leather. However, the utilization rate of chromium in the chrome tanning process is relatively low. In the process of tanning by conventional chrome tanning methods, the utilization rate of chromium is only 65% ​​to 75%, resulting in serious waste of resources. The remaining chrome tanning agent will be discharged along with the production wastewater, sludge and waste scraps, which not only increases the economic cost, but also leads to serious environmental pollution problems. Traditional leather manufacturing at home and abroad mainly adopts the chrome tanning method. The resulting chromium-containing wastewater, chromium-containing solid waste, chromium-containing waste leather products, etc. may cause environmental risks. This problem is gradually becoming a technical bottleneck restricting the sustainable development of the leather industry.

[0003] At present, the main methods for chrome-free ecological leather tanning are: non-chrome metal tanning, vegetable tanning, aldehyde tanning, and new organic tanning. Non-chrome metal tanning mainly includes tanning leather with non-chrome metal tanning agents such as zirconium, aluminum, titanium, iron, and zeolite. Compared with chrome tanned leather, the shrinkage temperature of non-chrome metal tanned leather is relatively low, the positive charge carried by white wet leather is too strong, the subsequent retanning and dyeing materials do not penetrate well, it is easy to bond to the surface, the leather is dry, flat and hard, and the physical properties and sensory properties are still far from the requirements of upper leather. Vegetable tanned leather does not contain heavy metals or formaldehyde, and has the advantages of non-toxicity, low pollution, and biodegradability. However, the combination of vegetable tanning agents and leather collagen is mainly the interaction mode of hydrogen bonds and hydrophobic bonds, and the binding ability is relatively weak and easily destroyed. Therefore, the performance of single vegetable tanning method tanning leather is unstable, the shrinkage temperature is not high, and the leather is hard, and there are not many applicable varieties. Aldehyde tanning mainly includes glutaraldehyde and organic phosphonate tanning. The advantages are simple tanning process, low tanning agent dosage, and no heavy metal pollution risk. The disadvantages are low shrinkage temperature, yellow tanned leather, low cationic charge of leather blank, low absorption and utilization rate of subsequent retanning and dyeing materials, high free formaldehyde content in the product, and the need to add a formaldehyde removal process. New organic tanning mainly includes F-90 tanning, TWS tanning, X-TAN tanning, Tanfor T tanning, etc., which are basically still in the experimental stage and have not yet formed a stable and mature production process. There are also disadvantages such as large amount of tanning agent required, insufficient fiber dispersion, low shrinkage temperature, low cationic charge of tanned white wet leather, low absorption and utilization rate of subsequent retanning and dyeing materials, and low physical and mechanical properties. Therefore, the research and development of environmentally friendly ecological leather is in line with the trend of high-quality development of the leather industry. Summary of the invention

[0004] The invention provides an environment-friendly water-dyed upper leather production process, so as to overcome the problems of serious pollution in the existing chrome tanning process, unstable chrome-free ecological leather tanning performance, hard leather and the like.

[0005] The present invention adopts the following technical solution:

[0006] An environmentally friendly water-dyed shoe upper leather production process, characterized in that it comprises the following steps:

[0007] Pickling bare hides → tanning → neutralization 1 → squeezing → shaving → retanning → neutralization 2 → dyeing → oiling → combined tanning → washing → drumming → dry finishing → finished product;

[0008] in,

[0009] Pickled bare hides are obtained by soaking, liming, splitting, deliming, softening, washing and pickling in a rotary drum according to conventional processes;

[0010] Tanning: based on the weight of the skin after splitting, add 30%-100% water and 1%-3% organic synthetic tanning agent TWS (Tingjiang New Materials Co., Ltd.) and rotate for 20-40 minutes; add 1%-3% organic synthetic tanning agent TWS and rotate for 20-40 minutes; add 1%-3% organic synthetic tanning agent TWS and rotate for 200-400 minutes;

[0011] Retanning: in a drum, based on the weight of the shaved wet leather, add 100%-200% of water and 1%-3% of oxalic acid, rotate for 20-60 minutes, and drain; add 30%-100% of water, 3%-6% of wattle bark tannin ME, 3%-6% of quebracho tannin ATO, 2%-6% of melamine resin DLF (BASF Chemical Co., Ltd.), 1%-5% of dicyandiamide resin HR (Templer Chemical Co., Ltd.), 1%-4% of urea-formaldehyde resin SK-10 (Saiqi Chemical Co., Ltd.), and rotate for 120-240 minutes;

[0012] Combined tanning: wash and drain, add 30%-100% water, 2%-6% zeolite tanning agent BIOSIN BS (Tiger Leather Technology (Shanghai) Co., Ltd.), rotate for 90-180 minutes; add 0.5%-1.5% sodium formate, rotate for 10-20 minutes; add 0.5%-1.5% baking soda, rotate for 20-60 minutes, detect the pH value to reach 5.0-5.5, and rotate for another 60 minutes.

[0013] Further, the above-mentioned neutralization 1 process is as follows: add 1%-3% sodium formate and rotate for 10-20 minutes; add 0.2%-0.5% baking soda and rotate for 10-30 minutes; repeatedly add 0.2%-0.5% baking soda and rotate for 10-30 minutes, until the detected pH value reaches 7.0-8.0; add 70%-150% water, heat to 35-45°C, rotate for 120-240 minutes, then rotate for 5 minutes and stop for 55 minutes overnight; wash with water the next day, drain the liquid, add 80%-150% water, 0.1%-0.4% mildew inhibitor 1336 (Bachman Laboratory Chemical (Shanghai) Co., Ltd.), 0.2%-0.5% formic acid, rotate for 10-30 minutes; repeatedly add 0.2%-0.5% formic acid and rotate for 10-30 minutes, until the detected pH value reaches 4.0-5.0; wash the drum with water, put it on the horse and let it stand, and tanning is completed.

[0014] Furthermore, the water squeezing reduces the moisture content of the tanned wet leather from 70%-80% to 40%-45% through a water squeezing machine, so as to facilitate the subsequent shaving process; the shaving thickness of normal upper leather is 1.15-1.20mm.

[0015] Furthermore, the above-mentioned neutralization 2 process is specifically as follows: add 0.5%-2% sodium formate and rotate for 10-30 minutes; add 0.4%-2% baking soda and rotate for 20-60 minutes, detect the pH value to reach 4.5-5.5, rotate for another 40-150 minutes, and wash and drain.

[0016] Furthermore, the dyeing process is as follows: add 50%-100% water, 0.2%-0.6% dyeing auxiliary LU (Derui Leather Technology (Qingdao) Co., Ltd.), and rotate for 10-30 minutes; add 0.5%-4% dye, and rotate for 60-120 minutes.

[0017] Furthermore, the above-mentioned refueling process is specifically as follows: add 50%-100% water, 2%-6% fish oil MIR 90, 5%-15% synthetic oil PELLASTOL 94S (Zima Chemical (Foshan) Co., Ltd.), heat to 45-55°C, rotate for 40-90 minutes; add 0.2%-0.6% formic acid, rotate for 10-30 minutes; then add 0.2%-0.6% formic acid, rotate for 10-30 minutes, detect the pH value to reach 3.8-4.5, and then rotate for 40-90 minutes.

[0018] Furthermore, the above-mentioned dry finishing includes stretching, vacuuming, hanging to dry, drying, returning water, vibrating to soften, tumbling to soften, stretching, painting, and quality inspection, that is, the finished product.

[0019] It can be seen from the above description of the present invention that, compared with the prior art, the present invention has the following advantages:

[0020] 1. The present invention provides an environmentally friendly water-dyed upper leather production process, firstly, the pickled bare leather is tanned with an amphoteric organic tanning agent TWS, which is an amphoteric organic synthetic tanning agent containing aldehyde, carboxyl and amino groups, with a small relative molecular weight, fast penetration speed, uniform dispersion, and the tanned white wet leather has fine grain, small position difference, white color, softness and fullness; then, the leather is retanned with a vegetable tanning agent and an amino resin, the vegetable tanning agent is composed of a polyphenol derivative, and the phenolic hydroxyl group of the vegetable tanning agent can be hydrogen bonded with the amide group of the collagen peptide chain of the leather to generate multi-point cross-linking to produce a tanning effect, and the amino resin is a general term for resins formed by condensation of a compound containing an amino group and formaldehyde, mainly including urea-formaldehyde resin, melamine resin and dicyandiamide resin, etc., with N-hydroxymethyl, imine group , urea and other active groups, which can be cross-linked with the carboxyl, amino, imine and other groups of the skin collagen fibers in the form of hydrogen bonds / covalent bonds, and have a strong selective filling effect; finally, zeolite tanning agent is used for combined tanning. Zeolite tanning agent is a water-containing alkali metal or alkaline earth metal aluminosilicate with silicon oxygen tetrahedron and aluminum oxygen tetrahedron structure, and forms a cross-linked synergistic network structure with skin collagen fibers, organic tanning agents and vegetable tanning agents, thereby improving the distribution uniformity and absorption rate of the tanning agent on all levels of the crust leather, and improving the binding force between the tanning agent and the skin collagen. The water resistance, organic solvent resistance and shrinkage temperature of the obtained crust leather are significantly improved; the obtained crust leather has fine grain and good compactness, and at the same time has good softness, fullness and elasticity, and is very suitable for water-dyed shoe upper leather products.

[0021] 2. The entire process of this application does not use chrome tanning agents or chrome-containing tanning agents, and no chrome-containing wastewater, sludge, or solid waste is generated. The hidden dangers of heavy metal pollution are eliminated from the source, saving environmental protection management costs, and complying with the trend of developing ecological leather.

[0022] 3. The shaved leather scraps and trimming scraps of the present application do not contain heavy metals and can be directly used to manufacture collagen to generate economic benefits.

[0023] 4. The free formaldehyde, hexavalent chromium and total chromium contents of the finished leather products of the present application are extremely low, or even undetectable.

[0024] 5. The shrinkage temperature of the finished leather product of this application reaches above 90°C, and its physical and chemical properties are better than the standard requirements of "QB / T5796-2023 Chrome-free tanned leather for shoe uppers". DETAILED DESCRIPTION

[0025] Embodiment 1:

[0026] The invention discloses an environmentally friendly water-dyed upper leather production process, the process of which includes: (pickling bare leather) → tanning → neutralization → squeezing water → shaving → retanning → neutralization → dyeing → oiling → combined tanning → washing → drumming → dry finishing → finished product.

[0027] (1) Pickled bare skin: soaking, liming, splitting, deliming, softening, washing and pickling in a rotary drum according to conventional processes;

[0028] (2) Tanning: Based on the weight of the skin after splitting, add 50% water and 2% organic synthetic tanning agent TWS (Tingjiang New Materials Co., Ltd.) and rotate for 30 minutes; add 2% organic synthetic tanning agent TWS and rotate for 30 minutes; add 2% organic synthetic tanning agent TWS and rotate for 300 minutes;

[0029] (3) Neutralization: add 2% sodium formate and rotate for 15 minutes; add 0.3% baking soda and rotate for 20 minutes; repeatedly add 0.3% baking soda and rotate for 20 minutes until the pH value reaches 7.5; add 100% water, heat to 40°C, rotate for 180 minutes, then rotate for 5 minutes and stop for 55 minutes overnight; wash with water the next day, drain, add 100% water, 0.2% mildew inhibitor 1336 (Bachman Laboratory Chemical (Shanghai) Co., Ltd.), 0.3% formic acid, rotate for 20 minutes; repeatedly add 0.3% formic acid and rotate for 20 minutes until the pH value reaches 4.5; wash out of the drum, mount and let stand, and tanning is completed;

[0030] (4) Squeezing: The moisture content of the tanned wet leather is reduced from 70%-80% to 40%-45% through a squeezing machine to facilitate the subsequent shaving process;

[0031] (5) Shaving: Normal upper leather shaving thickness is 1.15-1.20mm;

[0032] (6) Retanning: in a drum, based on the weight of the shaved wet leather, add 150% of water and 2% of oxalic acid, rotate for 40 minutes, and drain; add 50% of water, 5% of wattle bark tannin ME (Bisheng Chemical Co., Ltd.), 5% of quebracho tannin ATO (Fangzheng Import and Export Co., Ltd.), 4% of melamine resin DLF (BASF Chemical Co., Ltd.), 3% of dicyandiamide resin HR (Temperor Chemical Co., Ltd.), and 2% of urea-formaldehyde resin SK-10 (Saiqi Chemical Co., Ltd.), and rotate for 180 minutes;

[0033] (7) Neutralization: add 1% sodium formate and rotate for 15 minutes; add 0.8% baking soda and rotate for 40 minutes. When the pH value reaches 5.2, rotate for another 60 minutes and wash with water to drain the liquid;

[0034] (8) Dyeing: add 80% water and 0.4% dyeing auxiliary LU (Derui Leather Technology (Qingdao) Co., Ltd.), rotate for 15 minutes; add 2% dye and rotate for 80 minutes;

[0035] (9) Adding oil: add 70% water, 4% fish oil MIR 90, 9% synthetic oil PELLASTOL 94S (Zima Chemical (Foshan) Co., Ltd.), heat to 50°C, rotate for 60 minutes; add 0.4% formic acid, rotate for 15 minutes; add 0.4% formic acid again, rotate for 15 minutes, detect pH value to 3.0-3.5, and rotate for another 60 minutes;

[0036] (10) Combined tanning: wash and drain, add 50% water, 4% zeolite tanning agent BIOSIN BS (Tiger Leather Technology (Shanghai) Co., Ltd.), rotate for 120 minutes; add 1% sodium formate, rotate for 15 minutes; add 0.8% baking soda, rotate for 40 minutes, detect pH value to 5.2, and rotate for another 60 minutes;

[0037] (11) Washing, unloading, standing, and wet processing is completed;

[0038] (12) Dry finishing: including stretching, vacuuming, hanging, drying, water return, vibration softening, tumbling, stretching, painting, and quality inspection, i.e. finished product.

[0039] Embodiment 2:

[0040] The invention discloses an environmentally friendly water-dyed upper leather production process, the process of which includes: (pickling bare leather) → tanning → neutralization → squeezing water → shaving → retanning → neutralization → combined tanning → dyeing → oiling → washing → drumming → dry finishing → finished product.

[0041] (1) Pickled bare skin: soaking, liming, splitting, deliming, softening, washing and pickling in a rotary drum according to conventional processes;

[0042] (2) Tanning: Based on the weight of the skin after splitting, add 80% water and 3% organic synthetic tanning agent TWS (Tingjiang New Materials Co., Ltd.) and rotate for 50 minutes; add 3% organic synthetic tanning agent TWS and rotate for 300 minutes;

[0043] (3) Neutralization: add 1% sodium formate and rotate for 10 minutes; add 0.5% baking soda and rotate for 20 minutes; repeatedly add 0.5% baking soda and rotate for 20 minutes until the pH value reaches 7.5; add 100% water, heat to 40°C, rotate for 180 minutes, then rotate for 5 minutes and stop for 55 minutes overnight; wash with water the next day, drain, add 100% water, 0.3% mildew inhibitor 1336 (Bachman Laboratory Chemical (Shanghai) Co., Ltd.), 0.3% formic acid, rotate for 20 minutes; repeatedly add 0.3% formic acid and rotate for 20 minutes until the pH value reaches 4.5; wash out of the drum, mount and let stand, and tanning is completed;

[0044] (4) Squeezing: The moisture content of the tanned wet leather is reduced from 70%-80% to 40%-45% through a squeezing machine to facilitate the subsequent shaving process;

[0045] (5) Shaving: Normal upper leather shaving thickness is 1.15-1.20mm;

[0046] (6) Retanning: in a drum, based on the weight of the shaved wet leather, add 200% water and 3% oxalic acid, rotate for 40 minutes, and drain; add 80% water and 4% zeolite tanning agent BIOSIN BS (Tiger Leather Technology (Shanghai) Co., Ltd.), and rotate for 90 minutes;

[0047] (7) Neutralization: add 1% sodium formate and rotate for 15 minutes; add 1% baking soda and rotate for 30 minutes. When the pH value reaches 5.5, rotate for another 60 minutes and wash with water to drain the liquid;

[0048] (8) Combined tanning: add 50% water, 7% wattle bark tannin ME (Bisheng Chemical Co., Ltd.), 8% quebracho tannin ATO (Fangzheng Import and Export Co., Ltd.), and rotate for 180 minutes;

[0049] (9) Dyeing: add 0.4% dyeing auxiliary LU (Derui Leather Technology (Qingdao) Co., Ltd.), rotate for 15 minutes; add 2% dye, rotate for 80 minutes;

[0050] (10) Adding oil: add 100% water, 2% fish oil MIR 90, 9% synthetic oil PELLASTOL 94S (Zima Chemical (Foshan) Co., Ltd.), heat to 50°C, rotate for 60 minutes; add 0.3% formic acid, rotate for 15 minutes; add 0.3% formic acid again, rotate for 15 minutes, detect pH value to reach 4.2, and rotate for another 60 minutes;

[0051] (11) Washing, unloading, standing, and wet processing is completed;

[0052] (12) Dry finishing: including stretching, vacuuming, hanging, drying, water return, vibration softening, tumbling, stretching, painting, and quality inspection, i.e. finished product.

[0053] Experimental results

[0054] The finished leather product of the present invention is tested according to the standard "QB / T 5796-2023 Chrome-free tanned leather for shoe uppers", and the results are shown in the following table.

[0055] Chemical performance requirements

[0056]

[0057] Physical and mechanical properties requirements

[0058]

[0059] It can be concluded from the above experimental data that the free formaldehyde, hexavalent chromium and total chromium contents of the finished leather of the present invention are extremely low, or even undetectable, the shrinkage temperature of the finished leather reaches above 90°C, and the physical and chemical properties are better than the standard requirements of "QB / T 5796-2023 Chrome-free tanned leather for shoe uppers".

[0060] The above is only a specific implementation of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantial changes to the present invention using this concept shall be deemed as an infringement of the protection scope of the present invention.

Claims

1. An environmentally friendly water-dyed upper leather production process, characterized in that: The steps include: Pickling bare hides → tanning → neutralization 1 → squeezing → shaving → retanning → neutralization 2 → dyeing → oiling → combined tanning → washing → drumming → dry finishing → finished product; in, Pickled bare hides are obtained by soaking, liming, splitting, deliming, softening, washing and pickling in a rotary drum according to conventional processes; Tanning: based on the weight of the skin after splitting, add 30%-100% water and 1%-3% organic synthetic tanning agent TWS and rotate for 20-40 minutes; add 1%-3% organic synthetic tanning agent TWS and rotate for 20-40 minutes; Add 1%-3% of organic synthetic tanning agent TWS and rotate for 200-400 minutes; Retanning: in a drum, based on the weight of the shaved wet leather, add 100%-200% water and 1%-3% oxalic acid, rotate for 20-60 minutes, and drain; add 30%-100% water, 3%-6% wattle bark tannin ME, 3%-6% quebracho tannin ATO, 2%-6% melamine resin DLF, 1%-5% dicyandiamide resin HR, 1%-4% urea-formaldehyde resin SK-10, and rotate for 120-240 minutes; Combined tanning: wash and drain, add 30%-100% water, 2%-6% zeolite tanning agent BIOSIN BS, rotate for 90-180 minutes; add 0.5%-1.5% sodium formate, rotate for 10-20 minutes; add 0.5%-1.5% baking soda, rotate for 20-60 minutes, detect pH value to 5.0-5.5, and rotate for another 60 minutes.

2. The environmentally friendly water-dyed shoe upper leather production process according to claim 1, characterized in that: The neutralization 1 process is specifically as follows: add 1%-3% sodium formate and rotate for 10-20 minutes; add 0.2%-0.5% baking soda and rotate for 10-30 minutes; repeatedly add 0.2%-0.5% baking soda and rotate for 10-30 minutes, until the detected pH value reaches 7.0-8.0; add 70%-150% water, heat to 35-45°C, rotate for 120-240 minutes, then rotate for 5 minutes and stop for 55 minutes overnight; wash with water the next day, drain the liquid, add 80%-150% water, 0.1%-0.4% mildew inhibitor 1336, 0.2%-0.5% formic acid, rotate for 10-30 minutes; repeatedly add 0.2%-0.5% formic acid and rotate for 10-30 minutes, until the detected pH value reaches 4.0-5.0; wash the drum with water, put it on the horse and let it stand, and tanning is completed.

3. The environmentally friendly water-dyed shoe upper leather production process according to claim 1, characterized in that: The squeezing is to reduce the moisture content of the tanned wet leather from 70%-80% to 40%-45% through a squeezing machine, so as to facilitate the subsequent shaving process; the shaving thickness of normal upper leather is 1.15-1.20mm.

4. The environmentally friendly water-dyed shoe upper leather production process according to claim 1, characterized in that: The neutralization 2 process is specifically as follows: add 0.5%-2% sodium formate and rotate for 10-30 minutes; add 0.4%-2% baking soda and rotate for 20-60 minutes, detect the pH value to reach 4.5-5.5, rotate for another 40-150 minutes, and wash and drain.

5. The environmentally friendly water-dyed shoe upper leather production process according to claim 1, characterized in that: The dyeing process is specifically as follows: adding 50%-100% of water and 0.2%-0.6% of dyeing auxiliary agent LU, rotating for 10-30 minutes; adding 0.5%-4% of dye, rotating for 60-120 minutes.

6. The environmentally friendly water-dyed shoe upper leather production process according to claim 1, characterized in that: The refueling process is specifically as follows: add 50%-100% of water, 2%-6% of fish oil MIR 90, 5%-15% of synthetic oil PELLASTOL 94S, heat to 45-55°C, and rotate for 40-90 minutes; add 0.2%-0.6% of formic acid, rotate for 10-30 minutes; then add 0.2%-0.6% of formic acid, rotate for 10-30 minutes, detect that the pH value reaches 3.8-4.5, and then rotate for 40-90 minutes.

7. The environmentally friendly water-dyed shoe upper leather production process according to claim 1, characterized in that: The dry finishing includes stretching, vacuuming, hanging to air, drying, water returning, vibration softening, tumbling, stretching, painting, and quality inspection, i.e. the finished product.

Images