Manufacturing process of white crust leather for ecological instep leather

Abstract

The invention relates to a manufacturing process of white crust leather for ecological instep leather, which is characterized by comprising the following steps: de-ashing and softening bare leather, tanning, neutralizing for the first time, wringing, shaving, retanning, combined tanning, neutralizing for the second time, dyeing, oiling, washing, discharging from a drum, and finishing in a dry state to obtain a finished product. According to the manufacturing process of the white crust leather for the ecological instep leather, a chrome tanning agent or a chrome-containing tanning agent is not used in the whole process, chromium-containing wastewater, sludge and solid waste are not generated, the hidden danger of heavy metal pollution is fundamentally eliminated, and the environment-friendly treatment cost is saved.

Description

Technical Field

[0001] The invention relates to the technical field of leather manufacturing, in particular to a manufacturing process of white crust leather for ecological shoe upper leather. Background Art

[0002] Tanning is a key process in the leather industry. During the tanning process, the collagen fibers of the leather combine with the tanning agent, and the properties of the leather change fundamentally, turning it from leather to leather. The traditional leather manufacturing at home and abroad mainly adopts the chrome tanning method. The utilization rate of chromium in the chrome tanning process is relatively low. During the tanning process of the conventional chrome tanning method, the utilization rate of chromium is only 65% ​​to 75%. The remaining chrome tanning agent will be discharged along with the production wastewater, sludge and waste scraps, resulting in a waste of resources, an increase in manufacturing economic costs, and serious environmental pollution.

[0003] The new organic tanning methods mainly include F-90 tanning, TWS tanning, X-TAN tanning, Tanfor T tanning, etc. They are still in the experimental stage and have not yet formed a stable and mature production process. They still have disadvantages such as large amount of tanning agent required, insufficient fiber dispersion, low shrinkage temperature, low cationic charge of tanned wet white leather, low absorption and utilization rate of subsequent retanning and dyeing materials, and low physical and mechanical properties. Summary of the invention

[0004] The invention provides a white crust leather manufacturing process for ecological shoe upper leather, so as to overcome the problems of less positive charge of tanned white wet leather, low absorption utilization rate of subsequent retanning and dyeing materials, and low physical and mechanical properties in the existing tanning process.

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

[0006] A process for manufacturing white crust leather for ecological shoe upper leather, characterized in that it comprises the following steps: de-ashing and softening bare leather → tanning → neutralization 1 → squeezing water → shaving → retanning → combined tanning → neutralization 2 → dyeing → oiling → washing → drumming → dry finishing → finished product;

[0007] Deliming and softening bare hides: obtained by soaking, liming, splitting, deliming, softening and washing in a rotary drum according to conventional processes;

[0008] 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;

[0009] Retanning is carried out in a drum, based on the weight of the shaved wet white leather, adding 100%-200% of water and 1%-3% of oxalic acid, rotating for 20-60 minutes, and draining; adding 30%-100% of water, 5%-20% of white tannin RECORTAN TAN (BK Leather Chemical Co., Ltd.), 2%-6% of melamine resin DLF (BASF Chemical Co., Ltd.), 1%-5% of dicyandiamide resin HR (Templer Chemical Co., Ltd.), and 1%-4% of urea-formaldehyde resin SK-10 (Saiqi Chemical Co., Ltd.), and rotating for 120-240 minutes;

[0010] Combined tanning: drain the washing liquid, add 30%-100% water, 2%-6% zeolite tanning agent BIOSIN BS (Tiger Leather Technology (Shanghai) Co., Ltd.), and rotate for 90-180 minutes.

[0011] Further, the above-mentioned neutralization step 1 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.

[0012] Furthermore, the squeezing process is specifically as follows: the moisture content of the tanned wet leather is reduced from 70%-80% to 40%-45% by a squeezing machine, so as to facilitate the subsequent shaving process.

[0013] Furthermore, the shaving of the nappa upper leather is performed to a thickness of 1.15 to 1.20 mm.

[0014] Furthermore, the above-mentioned neutralization step 2 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 4.5-6.2, rotate for another 40-150 minutes, and wash and drain.

[0015] 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%-1.5% titanium dioxide, 1%-4% white pigment paste, and rotate for 60-120 minutes.

[0016] 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, and 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.

[0017] Furthermore, the above-mentioned dry finishing includes stretching, vacuum, hanging to air, drying, water return, vibration softening, tumbling, stretching, painting, and quality inspection, that is, the finished product.

[0018] 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:

[0019] 1. The manufacturing process of white crust leather for ecological shoe upper leather of the present application is firstly to tan the de-ashed and softened bare leather with an amphoteric organic tanning agent TWS. The TWS tanning agent is an amphoteric organic synthetic tanning agent containing aldehyde groups, carboxyl groups and amino groups, which can disperse and penetrate into the bare leather fiber under high pH conditions to realize a salt-free and non-pickling tanning process. The TWS has a small relative molecular mass, a fast penetration speed, and a uniform dispersion. Moreover, the tanned white wet leather has a fine grain surface, a small difference in position, a white color, and is soft and plump. Then, the white tanning agent white tannin and an amino resin are used for retanning. The vegetable tanning agent is composed of a polyphenol derivative, and its phenolic hydroxyl group can be hydrogen-bonded with the amide group of the collagen peptide chain of the skin to generate multi-point cross-linking to produce a tanning effect. The amino resin is a general term for resins formed by condensation of amino-containing compounds and formaldehyde, mainly urea-formaldehyde resin, melamine resin and Dicyandiamide resin, etc., have active groups such as N-methylol, imine, urea, etc., can be cross-linked with the carboxyl, amino, imine, etc. of the skin collagen fiber 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 the skin collagen fiber, organic tanning agent, vegetable tanning agent form a mutually cross-linked synergistic network structure, improve the distribution uniformity and absorption rate of the tanning agent on all levels of the crust leather, improve the binding force between the tanning agent and the skin collagen, and the water resistance, organic solvent resistance and shrinkage temperature of the obtained crust leather are significantly improved; the obtained crust leather has fine grain, good firmness, white color, and good softness, fullness and elasticity, which is very suitable for white shoe upper leather products.

[0020] 2. The entire manufacturing process of the white crust leather for the ecological upper leather of the present application does not use chrome tanning agents or chrome-containing tanning agents, and no chromium-containing wastewater, sludge, or solid waste is generated, thereby eliminating the hidden dangers of heavy metal pollution from the source and saving environmental protection management costs.

[0021] 3. The organic tanning agent TWS of the present application can realize a salt-free and non-acid tanning process, which reduces more than 90% of sulfate and chloride pollution compared with the traditional chrome tanning process and meets the requirements of ecological leather process.

[0022] 4. The shaved leather and trimming scraps of this application do not contain heavy metals and can be directly used to manufacture collagen to generate economic benefits.

[0023] 5. The free formaldehyde, hexavalent chromium and total chromium contents of the leather finished product of the present application are extremely low, or even undetectable.

[0024] 6. The leather of this application has a soft feel, fine grain, and white color, and does not require an additional bleaching process; the shrinkage temperature of the finished leather product reaches above 90°C, and the 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] A manufacturing process of white crust leather for ecological shoe upper leather, the process of which includes: (de-ashing and softening bare leather) → tanning → neutralization → squeezing water → shaving → retanning → combined tanning → neutralization → dyeing → oiling → washing → drumming → dry finishing → finished product.

[0027] (1) Deliming and softening bare skin: soaking, liming, splitting, deliming, softening and washing 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 240 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, 10% of white tannin RECORTAN TAN (BK Leather Chemical Co., Ltd.), 4% of melamine resin DLF (BASF Chemical Co., Ltd.), 3% of dicyandiamide resin HR (Templer Chemical Co., Ltd.), and 2% of urea-formaldehyde resin SK-10 (Saiqi Chemical Co., Ltd.), and rotate for 180 minutes;

[0033] (7) Combined tanning: wash and drain, add 50% water and 4% zeolite tanning agent BIOSIN BS (Tiger Leather Technology (Shanghai) Co., Ltd.), and rotate for 120 minutes;

[0034] (8) 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;

[0035] (9) Dyeing: add 80% water and 0.4% dyeing auxiliary LU (Derui Leather Technology (Qingdao) Co., Ltd.), and rotate for 15 minutes; add 1% titanium dioxide and 2% white pigment paste, and rotate for 80 minutes;

[0036] (10) Adding oil: add 70% water, 4% fish oil MIR 90, and 9% synthetic oil PELLASTOL 94S (Zima Chemical (Foshan) Co., Ltd.), heat to 50°C, and rotate for 60 minutes; add 0.4% formic acid, rotate for 15 minutes; add 0.4% formic acid again, rotate for 15 minutes, detect the pH value to reach 4.2, and rotate for another 20 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] A manufacturing process of white crust leather for ecological shoe upper leather, the process of which includes: (de-ashing and softening bare leather) → tanning → neutralization → squeezing water → shaving → retanning → combined tanning → neutralization → dyeing → oiling → washing → drumming → dry finishing → finished product.

[0041] (1) Deliming and softening bare skin: soaking, liming, splitting, deliming, softening and washing 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 40 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 0.3% 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, 0.3% mildew inhibitor 1336 (Bachman Laboratory Chemical (Shanghai) Co., Ltd.), 0.4% formic acid, rotate for 20 minutes; repeatedly add 0.4% 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: Nappa upper leather shaving thickness 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 60% water, 15% white tannin extract RECORTAN TAN (BK Leather Chemical Co., Ltd.), 3% melamine resin DLF (BASF Chemical Co., Ltd.), 3% dicyandiamide resin HR (Temper Chemical Co., Ltd.), and 3% urea-formaldehyde resin SK-10 (Saiqi Chemical Co., Ltd.), and rotate for 180 minutes;

[0047] (7) Combined tanning: wash and drain, add 60% water and 5% zeolite tanning agent BIOSIN BS (Tiger Leather Technology (Shanghai) Co., Ltd.), and rotate for 120 minutes;

[0048] (8) Neutralization: Add 1% sodium formate and rotate for 20 minutes; add 1.2% baking soda and rotate for 40 minutes. When the pH value reaches 5.2, rotate for another 120 minutes and wash with water to drain the liquid;

[0049] (9) Dyeing: add 70% water and 0.3% dyeing auxiliary LU (Derui Leather Technology (Qingdao) Co., Ltd.), and rotate for 20 minutes; add 1% titanium dioxide and 2% white pigment paste, and rotate for 90 minutes;

[0050] (10) Adding oil: add 70% water, 4% fish oil MIR 90, and 8% synthetic oil PELLASTOL 94S (Zima Chemical (Foshan) Co., Ltd.), heat to 48°C, and rotate for 60 minutes; add 0.3% formic acid, rotate for 20 minutes; add 0.3% formic acid again, rotate for 20 minutes, detect that the pH value reaches 4.0, and rotate for another 30 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 this application 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 seen from the above experimental data that the free formaldehyde, hexavalent chromium and total chromium contents of the finished leather products of this application are extremely low, or even undetectable; the leather has a soft hand feel, fine grain and white color, and no additional bleaching process is required; the shrinkage temperature of the finished leather product reaches above 90°C, and the physical and chemical properties are better than the "QB / T5796-2023 Chrome-free tanned leather for shoe uppers" standard requirements.

[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. A process for manufacturing white crust leather for ecological shoe upper leather, characterized in that: The steps include: de-liming and softening bare hides → tanning → neutralization 1 → squeezing → shaving → retanning → combined tanning → neutralization 2 → dyeing → oiling → washing → drumming → dry finishing → finished product; in, Deliming and softening bare hides: obtained by soaking, liming, splitting, deliming, softening and washing 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 is carried out in a drum, based on the weight of the shaved white wet leather, adding 100%-200% water and 1%-3% oxalic acid, rotating for 20-60 minutes, and draining; adding 30%-100% water, 5%-20% white tannin extract RECORTAN TAN, 2%-6% melamine resin DLF, 1%-5% dicyandiamide resin HR, 1%-4% urea-formaldehyde resin SK-10, and rotating for 120-240 minutes; Combined tanning: Wash the drain, add 30%-100% water, 2%-6% zeolite tanning agent BIOSIN BS, and rotate for 90-180 minutes.

2. The process for manufacturing white crust leather for ecological shoe upper leather according to claim 1, characterized in that: The neutralization step 1 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, 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 process for manufacturing white crust leather for ecological shoe upper leather according to claim 1, characterized in that: The squeezing process is specifically as follows: the moisture content of the tanned wet leather is reduced from 70%-80% to 40%-45% by a squeezing machine, so as to facilitate the subsequent shaving process.

4. The process for manufacturing white crust leather for ecological shoe upper leather according to claim 1, characterized in that: The shaving is performed so that the nappa upper leather has a shaving thickness of 1.15 to 1.20 mm.

5. The process for manufacturing white crust leather for ecological shoe upper leather according to claim 1, characterized in that: The neutralization step 2 is 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 4.5-6.2, rotate for another 40-150 minutes, and wash and drain.

6. The process for manufacturing white crust leather for ecological shoe upper leather according to claim 1, characterized in that: The dyeing process is specifically as follows: add 50%-100% water, 0.2%-0.6% dyeing auxiliary agent LU, and rotate for 10-30 minutes; add 0.5%-1.5% titanium dioxide, 1%-4% white pigment paste, and rotate for 60-120 minutes.

7. The process for manufacturing white crust leather for ecological shoe upper leather 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 PELLASTOL94S, 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.

8. The process for manufacturing white crust leather for ecological shoe upper leather 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.

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