A method for preparing and applying a leather repair ointment based on solid waste from leather tanning.

Abstract

This invention relates to a method for preparing a leather repair ointment based on solid waste from leather tanning. The method involves taking waste bovine hair, adding deionized water, acid, acidic protease, and hydrogen peroxide, filtering to remove impurities, and neutralizing. The hair is then dissolved in thionyl chloride, and 10 parts of N,N-dimethylformamide, pentaerythritol, sodium hydroxide, water, and ethanol are added. Titanium nitrate, copper nitrate, nickel nitrate, carboxylated keratin, and polycarboxyl ligands are dispersed in N,N-dimethylformamide. Carboxylated keratin powder, high-performance filler, oil and wax additives, and composite resin are added to obtain the leather repair ointment. This application uses an acid-enzyme combined method to hydrolyze waste bovine hair to prepare keratin. Glyoxylic acid is used to convert amino groups to carboxyl groups, promoting the formation of stable high-performance fillers by keratin and polycarboxylic acid ligands. This increases the carboxyl content of the high-performance filler, preparing hyperbranched organic matter with extremely strong coordination chelating ability. The remaining uncoordinated carboxyl groups can also improve the water dispersibility of the high-performance filler.

Description

Technical Field

[0001] This invention relates to the field of leather processing technology, and in particular to a method for preparing and applying a leather repair paste based on solid waste from leather processing. Background Technology

[0002] Among the many solid wastes from leather tanning, waste yak hair is characterized by its relatively simple composition and easy purification process. Under acidic conditions, enzymatic hydrolysis of waste yak hair can efficiently extract keratin. Keratin has a typical protein structure, composed of various amino acids through a dehydration condensation reaction between carboxyl and amino groups. The difference lies in the amino acid composition of keratin, which differs from collagen and hemoglobin, containing unique disulfide bonds. Therefore, in addition to its use as a protein filler in retanning for leather tanning, keratin can also be comprehensively utilized in leather finishing, acting as a filler to enhance the filling power and fullness of the coating, improving its fleshy feel. Summary of the Invention

[0003] This invention provides a method for preparing and applying a leather repair paste based on solid waste from leather tanning, in order to solve the problem of insufficient comprehensive utilization of keratin in existing leather tanning processes.

[0004] The present invention adopts the following technical solution:

[0005] A method for preparing a leather repair paste based on solid waste from leather tanning includes the following steps:

[0006] Step 1: Take 100 parts of washed waste cow hair, add 500 parts of deionized water, mix well, then add 8-12 parts of acid, 1-5 parts of acidic protease, and 2-5 parts of hydrogen peroxide. React at 45-60℃ for 3-6 hours. After cooling to room temperature, filter to remove impurities. Neutralize the filtrate with sodium hydroxide to 6-8, add 30-50 parts of glyoxylic acid, and react at 30-35℃ for 2-5 hours. Vacuum dry to obtain carboxylated keratin powder.

[0007] Step 2: Dissolve 600 parts of benzohexamic acid in 1800 parts of thionyl chloride, add 10 parts of N,N-dimethylformamide, react at 35-50℃ for 2-4 hours, remove excess thionyl chloride and N,N-dimethylformamide by rotary evaporation, then add 80-100 parts of pentaerythritol and 1 part of sodium hydroxide, react at 20-25℃ for 3-5 hours under nitrogen protection, then carefully add 300 parts of water and 300 parts of ethanol, continue the reaction for 1-3 hours, remove ethanol and water by rotary evaporation to obtain the polycarboxylic acid ligand;

[0008] Step 3: Disperse 20-50 parts of titanium nitrate, 0-10 parts of copper nitrate, 10-20 parts of nickel nitrate, 50-100 parts of carboxylated keratin, 20-40 parts of polycarboxylic acid ligand, 5-10 parts of cis-tetrahydrofuran-3,4-dicarboxylic acid, and 5-10 parts of 2,3-pyrazine dicarboxylic acid (CAS: 89-01-0) in 200-400 parts of N,N-dimethylformamide. After mixing evenly, heat to 120-140℃ and react for 24-48 hours. Slowly lower to room temperature and add 100-300 parts of N,N-dimethylformamide. Continue the reaction for 6-12 hours. After filtration, obtain the filter residue, wash repeatedly with N,N-dimethylformamide, and vacuum dry to obtain the high-performance packing material.

[0009] Step 4: Take 500 parts of repair ointment, add 50-100 parts of carboxylated keratin powder, 30-80 parts of high-performance filler, 10-20 parts of oil and wax additives, and 10-30 parts of composite resin. Disperse at high speed for 30 minutes to obtain keratin-based leather repair ointment.

[0010] Further improvements include using hydrochloric acid or sulfuric acid.

[0011] An application of a leather repair paste based on solid waste from leather tanning includes the following process: pressing a perforated plate (85℃ / 50kg / 3s) → softening (level 5-6) → scraping and patching → letting stand (3-6h) → polishing → brushing and patching → letting stand (3-6h) → pressing a flat plate (85℃ / 30kg / 1s) → thawing and softening (6-12h) → softening (level 5-6).

[0012] In a further improvement, the above-mentioned patching paste includes the following raw materials: 250-400 parts water, 50-100 parts leather repair paste based on leather solid waste, 20-50 parts wax, 10-30 parts sealing resin, and 10-30 parts cationic resin.

[0013] In a further improvement, the above-mentioned slurry for brushing and patching includes the following raw materials: 800-1000 parts water, 50-100 parts leather repair paste based on leather solid waste, 20-50 parts wax, 40-60 parts sealing resin, 10-30 parts cationic resin, 20-50 parts polyurethane resin, 50-100 parts oil and wax additives, and 50-100 parts penetrant.

[0014] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following advantages:

[0015] 1. This application describes a method for preparing keratin by hydrolyzing waste bovine hair using an acid-enzyme combination method. Keratin is a typical amphoteric molecule with a certain amount of carboxyl, amino, hydroxyl, and thiol groups in its molecular structure. Glyoxylic acid can convert amino groups to carboxyl groups, thereby increasing the negative charge of keratin. This increased negative charge enhances its coordination ability with cationic centers (such as metal ions), promoting the formation of stable, high-performance fillers by keratin and polycarboxylic acid ligands. It also improves the compatibility of keratin with anionic resins and oil-based wax additives. The small molecule keratin can also regulate the interfacial compatibility between anionic resins and oil-based wax additives, promoting system homogenization and thus forming a stable repair ointment system.

[0016] 2. To further improve the carboxyl content of high-performance fillers, this application prepares a hyperbranched organic compound with multiple carboxyl groups. Using pentaerythritol as the core, primary hyperbranching yields a hyperbranched structure with 15-20 carboxyl groups. This hyperbranched structure possesses extremely strong coordination chelating ability. Due to steric hindrance, the remaining uncoordinated carboxyl groups can also improve the water dispersibility of the high-performance filler. Keratin and multi-carboxyl complexes can also chelate heavy metals that may be introduced during leather tanning, thereby reducing the content of leached heavy metals in leather and coatings.

[0017] 3. The carboxylated keratin of this application exhibits good anionicity, with a zeta potential ≤ -35mV, and also possesses a suitable particle size and good dispersibility, with a particle size of 200-500nm and a particle size distribution coefficient of 0.150-0.300. The carboxylated keratin also exhibits excellent water solubility, with a solid content ≥90%, water-insoluble content ≤2%, and water-soluble content ≥88%.

[0018] 4. The high-performance packing material of this application has a huge specific surface area and high reactivity, which can adsorb various gaseous VOCs. Taking 200g of high-performance packing material as an example, it can adsorb VOCs in a 1.5m³ medium. 3 The adsorption rates for acetone, benzene, toluene, xylene, and 1,2-dichloroethane at concentrations up to 2000 ppm are all ≥90%. Furthermore, the adsorption capacity for various heavy metals such as arsenic, lead, cadmium, and antimony is ≥100 mg·g. -1 .

[0019] 5. The raw leather repaired with tanning repair paste based on tanning solid waste can effectively cover up defects, thereby improving the utilization rate and consistency of the leather. At the same time, the appropriate amount of oil and wax additives can also improve the oil and wax color-changing properties of the finished leather and give the leather a better oily feel. The leather treated with tanning repair paste based on tanning solid waste has VOC ≤100μg / g, heavy metal arsenic ≤100ppm, lead ≤100ppm, cadmium ≤100ppm, soluble arsenic ≤1ppm, and soluble antimony ≤30ppm. Detailed Implementation

[0020] Example 1:

[0021] A method for preparing a leather repair paste based on solid waste from leather tanning includes the following steps:

[0022] Step 1, Preparation of carboxylated keratin powder: Take 100 parts of washed waste cow hair, add 500 parts of deionized water, mix well, then add 8 parts of sulfuric acid, 4 parts of acidic protease (4084, Lanxess Chemical), and 3 parts of hydrogen peroxide. React at 50℃ for 4 hours. After cooling to room temperature, filter to remove impurities. Neutralize the filtrate with sodium hydroxide to 7, add 50 parts of glyoxylic acid, react at 30℃ for 4 hours, and vacuum dry to obtain carboxylated keratin powder.

[0023] Step 2, Preparation of polycarboxylic acid ligands: Dissolve 600 parts of benzohexanic acid in 1800 parts of thionyl chloride, add 10 parts of N,N-dimethylformamide, react at 35°C for 4 hours, remove excess thionyl chloride and N,N-dimethylformamide by rotary evaporation, then add 80 parts of pentaerythritol and 1 part of sodium hydroxide, react at 25°C for 3 hours under nitrogen protection, then carefully add 300 parts of water and 300 parts of ethanol, continue the reaction for 2 hours, remove ethanol and water by rotary evaporation to obtain polycarboxylic acid ligands.

[0024] Step 3, Preparation of high-performance packing material: 40 parts titanium nitrate, 5 parts copper nitrate, 15 parts nickel nitrate, 80 parts carboxylated keratin, 25 parts polycarboxylic acid ligand, 5 parts cis-tetrahydrofuran-3,4-dicarboxylic acid (CAS: 149429-49-2), and 10 parts 2,3-pyrazine dicarboxylic acid (CAS: 89-01-0) are dispersed in 200 parts N,N-dimethylformamide. After mixing evenly, the mixture is heated to 140℃ and reacted for 24 hours. After slowly lowering the temperature to room temperature, 300 parts N,N-dimethylformamide are added, and the reaction continues for 6 hours. After filtration, the filter residue is obtained, repeatedly washed with N,N-dimethylformamide, and vacuum dried to obtain the high-performance packing material.

[0025] Step 4, Preparation of keratin-based leather repair ointment: Take 500 parts of repair ointment (8185, Magee Chemical), add 50 parts of carboxylated keratin powder, 80 parts of high-performance filler, 10 parts of oil and wax additive (Fl-50, Starr), and 30 parts of composite resin (Rl-115, Starr), and disperse at high speed for 30 minutes to obtain keratin-based leather repair ointment.

[0026] Example 2:

[0027] A method for preparing a leather repair paste based on solid waste from leather tanning includes the following steps:

[0028] Step 1, Preparation of carboxylated keratin powder: Take 100 parts of washed waste cow hair, add 500 parts of deionized water, mix well, then add 5 parts of sulfuric acid, 5 parts of hydrochloric acid, 3 parts of acidic protease (4084, Lanxess Chemical), and 4 parts of hydrogen peroxide. React at 45℃ for 6 hours. After cooling to room temperature, filter to remove impurities. Neutralize the filtrate with sodium hydroxide to 8, add 40 parts of glyoxylic acid, and react at 32℃ for 3 hours. Vacuum drying will yield carboxylated keratin powder.

[0029] Step 2, Preparation of polycarboxylic acid ligands: Dissolve 600 parts of benzohexanic acid in 1800 parts of thionyl chloride, add 10 parts of N,N-dimethylformamide, react at 40°C for 3 hours, remove excess thionyl chloride and N,N-dimethylformamide by rotary evaporation, then add 100 parts of pentaerythritol and 1 part of sodium hydroxide, react at 20°C for 5 hours under nitrogen protection, then carefully add 300 parts of water and 300 parts of ethanol, continue the reaction for 3 hours, remove ethanol and water by rotary evaporation to obtain polycarboxylic acid ligands.

[0030] Step 3, Preparation of high-performance packing material: 40 parts of titanium nitrate, 20 parts of nickel nitrate, 50 parts of carboxylated keratin, 40 parts of polycarboxylic acid ligand, 10 parts of cis-tetrahydrofuran-3,4-dicarboxylic acid (CAS: 149429-49-2), and 10 parts of 2,3-pyrazine dicarboxylic acid (CAS: 89-01-0) are dispersed in 300 parts of N,N-dimethylformamide. After mixing evenly, the mixture is heated to 130℃ and reacted for 36 hours. After slowly lowering the temperature to room temperature, 200 parts of N,N-dimethylformamide are added, and the reaction continues for 9 hours. After filtration, the filter residue is obtained, repeatedly washed with N,N-dimethylformamide, and vacuum dried to obtain the high-performance packing material.

[0031] Step 4, Preparation of keratin-based leather repair ointment: Take 500 parts of repair ointment (8185, Maggie Chemicals), add 80 parts of carboxylated keratin powder, 50 parts of high-performance filler, 20 parts of oil and wax additive (Fl-64, Starr), and 10 parts of composite resin (Rl-2060, Starr), and disperse at high speed for 30 minutes to obtain keratin-based leather repair ointment.

[0032] Example 3:

[0033] A method for preparing a leather repair paste based on solid waste from leather tanning includes the following steps:

[0034] Step 1, Preparation of carboxylated keratin powder: Take 100 parts of washed waste cow hair, add 500 parts of deionized water, mix well, then add 8 parts of sulfuric acid, 4 parts of hydrochloric acid, 2 parts of acidic protease (4084, Lanxess Chemical), and 2 parts of hydrogen peroxide. React at 55℃ for 3 hours. After cooling to room temperature, filter to remove impurities. Neutralize the filtrate with sodium hydroxide to 6, add 30 parts of glyoxylic acid, and react at 35℃ for 5 hours. Vacuum drying will yield carboxylated keratin powder.

[0035] Step 2, Preparation of polycarboxylic acid ligands: Dissolve 600 parts of benzohexamic acid in 1800 parts of thionyl chloride, add 10 parts of N,N-dimethylformamide, react at 45°C for 2 hours, remove excess thionyl chloride and N,N-dimethylformamide by rotary evaporation, then add 90 parts of pentaerythritol and 1 part of sodium hydroxide, react at 22°C for 4 hours under nitrogen protection, then carefully add 300 parts of water and 300 parts of ethanol, continue the reaction for 1 hour, remove ethanol and water by rotary evaporation to obtain polycarboxylic acid ligands.

[0036] Step 3, Preparation of high-performance packing material: 20 parts titanium nitrate, 10 parts copper nitrate, 20 parts nickel nitrate, 75 parts carboxylated keratin, 35 parts polycarboxylic acid ligand, 5 parts cis-tetrahydrofuran-3,4-dicarboxylic acid (CAS: 149429-49-2), and 5 parts 2,3-pyrazine dicarboxylic acid (CAS: 89-01-0) are dispersed in 400 parts N,N-dimethylformamide. After mixing evenly, the mixture is heated to 120℃ and reacted for 48 hours. After slowly lowering the temperature to room temperature, 100 parts N,N-dimethylformamide are added, and the reaction continues for 12 hours. After filtration, the filter residue is obtained, repeatedly washed with N,N-dimethylformamide, and vacuum dried to obtain the high-performance packing material.

[0037] Step 4, Preparation of keratin-based leather repair ointment: Take 500 parts of repair ointment (8185, Magee Chemical), add 100 parts of carboxylated keratin powder, 30 parts of high-performance filler, 15 parts of oil and wax additive (Fl-50, Starr), and 20 parts of composite resin (Rl-77-100, Starr), and disperse at high speed for 30 minutes to obtain keratin-based leather repair ointment.

[0038] The carboxylated keratin and high-performance fillers obtained in Examples 1, 2, and 3 were subjected to practical testing, and the experimental data are shown in Table 1 below:

[0039]

[0040] Example 4:

[0041] An application of a leather repair paste based on solid waste from leather tanning includes the following process: pressing a perforated plate (85℃ / 50kg / 3s) → softening (level 5-6) → scraping and patching → letting stand (3-6h) → polishing → brushing and patching → letting stand (3-6h) → pressing a flat plate (85℃ / 30kg / 1s) → thawing and softening (6-12h) → softening (level 5-6).

[0042] The aforementioned patching paste includes the following raw materials: 300 parts water, 100 parts leather repair paste based on leather solid waste, 30 parts wax (NU, Stahl), 20 parts sealing resin (2029, Lanxess Chemical), and 15 parts cationic resin (UP, Stahl).

[0043] The above-mentioned slurry for brushing and patching includes the following raw materials: 800 parts water, 50 parts leather repair paste based on leather solid waste, 50 parts wax (NU, Stahl), 60 parts sealing resin (2029, Lanxess Chemical), 20 parts cationic resin (UP, Stahl), 50 parts polyurethane resin (77-197, Stahl), 50 parts oil and wax additives (BG, Stahl), and 50 parts penetrant (ethylene glycol monoethyl ether, Stahl).

[0044] The leather repair paste based on leather tanning solid waste in this embodiment was prepared in Example 1.

[0045] Example 5:

[0046] The application of the leather repair ointment based on tanning solid waste in this embodiment is basically the same as that in embodiment 4. The difference is that the leather repair ointment based on tanning solid waste in this embodiment is prepared in embodiment 2.

[0047] Example 6:

[0048] The application of the leather repair ointment based on tanning solid waste in this embodiment is basically the same as that in embodiment 4. The difference is that the leather repair ointment based on tanning solid waste in this embodiment is prepared in embodiment 3.

[0049] The raw leathers obtained in Examples 4, 5, and 6 were subjected to practical testing, and the experimental data are shown in Table 2 below.

[0050] Table 2

[0051]

[0052] 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 a leather repair paste based on solid waste from leather tanning, characterized in that, Includes the following steps: Step 1: Take 100 parts of washed waste cow hair, add 500 parts of deionized water, mix well, then add 8-12 parts of acid, 1-5 parts of acidic protease, and 2-5 parts of hydrogen peroxide. React at 45-60℃ for 3-6 hours. After cooling to room temperature, filter to remove impurities. Neutralize the filtrate with sodium hydroxide to 6-8, add 30-50 parts of glyoxylic acid, and react at 30-35℃ for 2-5 hours. Vacuum dry to obtain carboxylated keratin powder. Step 2: Dissolve 600 parts of benzohexamic acid in 1800 parts of thionyl chloride, add 10 parts of N,N-dimethylformamide, react at 35-50℃ for 2-4 hours, remove excess thionyl chloride and N,N-dimethylformamide by rotary evaporation, then add 80-100 parts of pentaerythritol and 1 part of sodium hydroxide, react at 20-25℃ for 3-5 hours under nitrogen protection, then carefully add 300 parts of water and 300 parts of ethanol, continue the reaction for 1-3 hours, remove ethanol and water by rotary evaporation to obtain the polycarboxylic acid ligand; Step 3: Disperse 20-50 parts of titanium nitrate, 0-10 parts of copper nitrate, 10-20 parts of nickel nitrate, 50-100 parts of carboxylated keratin, 20-40 parts of polycarboxylic acid ligand, 5-10 parts of cis-tetrahydrofuran-3,4-dicarboxylic acid, and 5-10 parts of 2,3-pyrazine dicarboxylic acid in 200-400 parts of N,N-dimethylformamide. After mixing evenly, heat to 120-140℃ and react for 24-48 hours. Slowly lower to room temperature and add 100-300 parts of N,N-dimethylformamide. Continue the reaction for 6-12 hours. After filtration, obtain the filter residue, wash repeatedly with N,N-dimethylformamide, and vacuum dry to obtain the high-performance packing material. Step 4: Take 500 parts of repair ointment, add 50-100 parts of carboxylated keratin powder, 30-80 parts of high-performance filler, 10-20 parts of oil and wax additives, and 10-30 parts of composite resin. Disperse at high speed for 30 minutes to obtain keratin-based leather repair ointment.

2. The method for preparing a leather repair ointment based on leather tanning solid waste as described in claim 1, characterized in that: The acid is either hydrochloric acid or sulfuric acid.

3. The application of a leather repair ointment based on leather tanning solid waste as described in claim 1 or 2, characterized in that, The process includes the following steps: pressing the perforated plate → softening → scraping and patching → resting → polishing → brushing and patching → resting → pressing the plate → thawing and softening → stretching and softening.

4. The application of a leather repair ointment based on leather tanning solid waste as described in claim 3, characterized in that, The patching paste comprises the following raw materials: 250-400 parts water, 50-100 parts leather repair paste based on leather solid waste, 20-50 parts wax, 10-30 parts sealing resin, and 10-30 parts cationic resin.

5. The application of a leather repair ointment based on leather tanning solid waste as described in claim 3, characterized in that, The slurry for brushing and patching includes the following raw materials: 800 parts water, 50 parts leather repair paste based on leather solid waste, 50 parts wax, 60 parts sealing resin, 20 parts cationic resin, 50 parts polyurethane resin, 50 parts oil and wax additives, and 50 parts penetrant.

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