Preparation method and application of sulfonated UV-resistant retanning agent based on collagen

Abstract

The present invention relates to a preparation method and application of a sulfonated UV-resistant retanning agent based on collagen, taking blue leather scraps, adding deionized water, alkali, adding calcium oxide, polyaluminium chloride, polyacrylamide flocculation precipitation, filtering, taking filtrate, adding sulfuric acid to adjust pH value to 6-8, vacuum drying to obtain collagen powder; adding manganese chloride, aluminium chloride, titanium chloride, 2-bithiophene-5,5-dicarboxylic acid, collagen powder, etc. are placed in a mixed solution of N, N-dimethylformamide, ethanol, water and nitric acid, mixing, filtering, drying, and obtaining UV-resistant retanning agent. The sulfonated UV-resistant retanning agent of the present application carries a variety of functional groups, including carboxyl, amino, hydroxyl, sulfonic acid group, and forms electrostatic interaction or hydrogen bonding association with carboxyl, amino, hydroxyl on skin collagen fibers, and the hydrogen bond network constructed thereof has extremely strong stability, and the sulfonated UV-resistant retanning agent can form π-π interactions through the aromatic rings of synthetic tannins, tannin extracts and other materials, and is fixed in skin collagen fibers.

Description

Technical Field

[0001] The invention relates to the technical field of leather making, and in particular to a preparation method and application of a sulfonated UV-resistant retanning agent based on collagen. Background Art

[0002] The tanning blue leather scraps mainly contain about 55% water, 40% organic matter, and 5% inorganic salts, among which the organic matter is mainly collagen, a natural polymer containing carboxyl and amino groups. Collagen has fewer unsaturated functional groups on the long chain and is a natural UV-resistant material. The rich carboxyl and amino groups on the long chain also make collagen a good ligand that can be used to prepare coordination compounds. Therefore, theoretically, leather processed using only collagen as a retanning filling material has excellent light resistance. However, the physical and mechanical properties and sensory properties of leather processed using only collagen are greatly lost. Therefore, if the UV resistance of leather is to be further improved, it is necessary to introduce organic matter that can capture ultraviolet rays, that is, ultraviolet absorbers. Ultraviolet absorbers can efficiently absorb ultraviolet rays through the tautomerism of intramolecular hydrogen bonds, and release the absorbed energy in the form of heat energy or other lower energy to return to the initial state. Summary of the invention

[0003] The invention provides a preparation method and application of a sulfonated UV-resistant retanning agent based on collagen, so as to solve the problem that the UV resistance of existing leather is poor.

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

[0005] A method for preparing a sulfonated UV-resistant retanning agent based on collagen comprises the following steps:

[0006] Step 1, take 100 parts of blue leather scraps, add 500 parts of deionized water, mix well and then add 8-12 parts of alkali, react at 60-90°C for 3-6 hours, cool to room temperature, add 5-10 parts of calcium oxide, 1 part of polyaluminum chloride and 1 part of polyacrylamide for flocculation precipitation, filter the precipitate, take the filtrate, add sulfuric acid to adjust the pH value to 6-8, and vacuum dry to obtain collagen powder.

[0007] Step 2, take 20-30 parts of manganese chloride, 40-65 parts of aluminum chloride, 0-15 parts of titanium chloride, 10-25 parts of 2,2-bithiophene-5,5-dicarboxylic acid, 0-15 parts of 2,3-pyrazine dicarboxylic acid, 20-40 parts of collagen powder, 2-8 parts of benzotriazole organic matter and put them into a mixed solution of 150 parts of N,N-dimethylformamide, 10 parts of ethanol, 5 parts of water and 1 part of nitric acid, mix them evenly, react at 75-90°C for 36-72h, slowly reduce the temperature to room temperature, add 100 parts of N,N-dimethylformamide and 1 part of nitric acid, react at room temperature for 24h, then filter, wash repeatedly with N,N-dimethylformamide, and vacuum dry to obtain a UV-resistant retanning agent.

[0008] Step 3, preparation of sulfonated UV-resistant retanning agent: 100 parts of UV-resistant retanning agent powder and 5-15 parts of sodium pyrosulfite are dissolved in 200-300 parts of water, mixed evenly, reacted at 80-100°C for 3h, and then the product is vacuum dried to obtain a sulfonated transition metal coordinated polymer material retanning agent.

[0009] In a further improvement, the alkali is one or more of sodium hydroxide, potassium hydroxide, and calcium oxide.

[0010] In a further improvement, the above-mentioned benzotriazole-based organic compound is one or more of 2, (2'-hydroxy-5'-methylphenyl) benzotriazole, 2, (2'-hydroxy-3', 5'-di-tert-butylphenyl) benzotriazole, 2, (2'4'-dihydroxyphenyl) benzotriazole, and 2- (2'-hydroxy-4'aminophenyl) benzotriazole.

[0011] An application of a sulfonated UV-resistant retanning agent based on collagen, comprising at least a retanning process and a filling process;

[0012] The specific steps of the retanning process are: based on the weight of the wet blue leather, controlling the drum temperature to be 30-35° C., adding 50-100% of water, adding 2-4% of an acid-resistant fatliquor, 0-3% of aliphatic aldehyde, rotating for 20 minutes, adding 4-6% of chrome powder, 1-3% of a sulfonated UV-resistant retanning agent, rotating for 60 minutes, and then adding 1% of sodium formate, rotating for 30 minutes, and then adding 0.8% of baking soda in three times, rotating for 10, 10, and 60 minutes;

[0013] The specific steps of the filling process are: based on the weight of the wet blue leather, the drum temperature is controlled to be 30-35°C, 50-100% of water, 2-4% of amphoteric acrylic acid, 4-8% of anionic acrylic acid are added, and the drum is rotated for 20-40 minutes; then 4-6% of dicyandiamide resin, 4-6% of melamine resin, 4-6% of tannin extract, 2% of dispersed tannin, 1-3% of fatliquor are added, and the drum is rotated for 40-60 minutes; then 4-6% of tannin extract, 2-4% of synthetic tanning agent, 1-3% of fatliquor are added, and the drum is rotated for 120 minutes; finally 1-3% of sulfonated UV-resistant retanning agent is added, and the drum is rotated for 20-60 minutes.

[0014] 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:

[0015] 1. Synthesis principle: The electron pairs on the carboxyl, amino, and hydroxyl groups of the present application can form coordination bonds with the hollow hybrid orbitals of metal ions. Depending on the different hybrid orbitals, coordination compounds with coordination numbers of 4, 6, 8, etc. can be formed. If the organic matter contains multiple active functional groups, a multi-nuclear complex can be formed under the condition of small steric hindrance. However, the formation of multi-nuclear complexes will rapidly increase the molecular weight of the material. When the molecular weight reaches a certain level, the complex becomes water-insoluble. Therefore, if the UV-resistant retanning agent is to be used in leather retanning, it is necessary to perform hydrophilic modification on it to improve its water solubility. Since there are a large number of benzene rings and heterocyclic aromatic structures in the complex, sulfonic acid groups can be grafted onto the benzene rings and heterocyclic aromatic structures through sulfonation to improve the water solubility of the composite material.

[0016] 2. Principle of improving UV resistance: The mechanism of action of the benzotriazole ultraviolet absorber of the present application is to convert the absorbed light energy into heat energy or other lower energy through molecular tautomerism. At the beginning, the molecule exists in the form of a lipid compound. After absorbing ultraviolet rays, the electron cloud density is transferred from the oxygen atom to the nitrogen atom of the triazole ring, making the nitrogen atom alkaline, and the proton is transferred to the nitrogen atom, thereby forming an unstable tautomer. Since the tautomer is in an unstable state, it will release the absorbed energy in the form of heat energy or other lower energy and return to the stable ground state.

[0017] 3. The water solubility of benzotriazole UV absorbers is relatively general, even 2-(2'-hydroxy-4'aminophenyl)benzotriazole is relatively general, and its relatively general water solubility results in its poor ability to bind to skin collagen fibers. Although it is a small molecule and can enter and exit the gaps between skin collagen fibers more freely, the loss of water solubility makes it difficult to fix between skin collagen fibers. Through the multi-core complex tanning agent with manganese, aluminum, and titanium as the core structure, the benzotriazole material can be well formed with the metal ion to form a coordination bond, and the molecular weight of the complex can be further increased through the chelation of collagen, 2,2-bithiophene-5,5-dicarboxylic acid, and 2,3-pyrazine dicarboxylic acid, so that the benzotriazole UV absorber can be better fixed in the complex.

[0018] 4. The sulfonated UV-resistant retanning agent of the present application carries a variety of functional groups, including carboxyl, amino, hydroxyl, and sulfonic acid groups, which can form electrostatic interactions or hydrogen bond associations with carboxyl, amino, and hydroxyl groups on the skin collagen fibers. The hydrogen bond network constructed by the sulfonated UV-resistant retanning agent has extremely strong stability. At the same time, the sulfonated UV-resistant retanning agent can form π-π interactions through the aromatic rings of synthetic tannins, tannin extracts and other materials, and further fix them in the skin collagen fibers. The sulfonated UV-resistant retanning agent is configured into a 2% aqueous solution, with a particle size of 1500-2800nm ​​and a particle size distribution coefficient of 0.200-0.450. The particle size is moderate and can better enter the skin collagen fibers. At the same time, the relatively concentrated particle size distribution coefficient also indicates that the sulfonated UV-resistant retanning agent has good aqueous solution dispersion performance.

[0019] 5. The unsulfonated UV-resistant retanning agent of the present application has extremely strong stability, and the mass loss rate is less than 2% after being immersed in an aqueous solution for 1 hour. The sulfonated UV-resistant retanning agent also has extremely strong stability, and no obvious precipitation is produced in a 10% sulfonated UV-resistant retanning agent aqueous solution under acidic (pH=3) and neutral (pH=7) conditions.

[0020] 6. The sulfonated UV-resistant retanning agent of the present application can significantly improve the yellowing resistance of the crust leather. After the crust leather is treated with the sulfonated UV-resistant retanning agent, the yellowing resistance can be improved from level 2-3 to level 4.

[0021] 7. The polyaromatic ring structure of the sulfonated UV-resistant retanning agent of the present application has the performance of highly efficient adsorption of synthetic dyes, and can also play a role in promoting dyeing and leveling dyeing. DETAILED DESCRIPTION

[0022] Embodiment 1:

[0023] A method for preparing a sulfonated UV-resistant retanning agent based on collagen comprises the following steps:

[0024] Step 1, preparation of collagen powder: take 100 parts of blue leather scraps, add 500 parts of deionized water, mix well and add 8 parts of potassium hydroxide, react at 75°C for 5 hours, cool to room temperature, add 10 parts of calcium oxide, 1 part of polyaluminum chloride, and 1 part of polyacrylamide for flocculation precipitation, filter the precipitate, take the filtrate, add sulfuric acid to adjust the pH to 7, and vacuum dry to obtain collagen powder.

[0025] Step 2, preparation of UV-resistant retanning agent: 20 parts of manganese chloride, 50 parts of aluminum chloride, 15 parts of titanium chloride, 15 parts of 2,2-bithiophene-5,5-dicarboxylic acid, 25 parts of collagen powder, 8 parts of 2-(2'-hydroxy-4'aminophenyl)benzotriazole (CAS: 3234-33-1) are placed in a mixed solution of 150 parts of N,N-dimethylformamide, 10 parts of ethanol, 5 parts of water and 1 part of nitric acid, mixed evenly, reacted at 80°C for 48h, slowly lowered to room temperature, added 100 parts of N,N-dimethylformamide and 1 part of nitric acid, reacted at room temperature for 24h, then filtered, repeatedly washed with N,N-dimethylformamide, and vacuum dried to obtain a UV-resistant retanning agent.

[0026] Step 3, preparation of sulfonated UV-resistant retanning agent: 100 parts of UV-resistant retanning agent powder and 5 parts of sodium pyrosulfite are dissolved in 220 parts of water, mixed evenly, reacted at 82°C for 3h, and then the product is vacuum dried to obtain a sulfonated transition metal coordinated polymer material retanning agent.

[0027] Embodiment 2:

[0028] A method for preparing a sulfonated UV-resistant retanning agent based on collagen comprises the following steps:

[0029] Step 1: Preparation of collagen powder: Take 100 parts of blue leather shavings, add 500 parts of deionized water, mix well, add 4 parts of sodium hydroxide and 8 parts of calcium oxide, react at 65°C for 6 hours, cool to room temperature, add 6 parts of calcium oxide, 1 part of polyaluminum chloride, and 1 part of polyacrylamide for flocculation precipitation, filter the precipitate, take the filtrate, add sulfuric acid to adjust the pH to 6, and vacuum dry to obtain collagen powder.

[0030] Step 2: Preparation of UV-resistant retanning agent: 25 parts of manganese chloride, 45 parts of aluminum chloride, 10 parts of 2,2-bithiophene-5,5-dicarboxylic acid, 10 parts of 2,3-pyrazine dicarboxylic acid, 30 parts of collagen powder, 2 parts of 2, (2'-hydroxy-5'-methylphenyl) benzotriazole (CAS: 2440-22-4), 4 parts of 2, (2'4'-dihydroxyphenyl) benzotriazole (CAS: 22607-31-4) are placed in a mixed solution of 150 parts of N, N-dimethylformamide, 10 parts of ethanol, 5 parts of water and 1 part of nitric acid, mixed evenly, reacted at 75°C for 60h, slowly lowered to room temperature, added 100 parts of N, N-dimethylformamide and 1 part of nitric acid, reacted at room temperature for 24h, then filtered, repeatedly washed with N, N-dimethylformamide, and vacuum dried to obtain a UV-resistant retanning agent.

[0031] Step 3: Preparation of sulfonated UV-resistant retanning agent: 100 parts of UV-resistant retanning agent powder and 8 parts of sodium metabisulfite are dissolved in 285 parts of water, mixed evenly, reacted at 95°C for 3 hours, and then the product is vacuum dried to obtain a sulfonated transition metal coordinated polymer material retanning agent.

[0032] Embodiment 3:

[0033] A method for preparing a sulfonated UV-resistant retanning agent based on collagen comprises the following steps:

[0034] Step 1: Preparation of collagen powder: Take 100 parts of blue leather shavings, add 500 parts of deionized water, mix well, add 8 parts of calcium oxide and 2 parts of potassium hydroxide, react at 60-90°C for 3-6 hours, cool to room temperature, add 6 parts of calcium oxide, 1 part of polyaluminum chloride, and 1 part of polyacrylamide for flocculation precipitation, filter the precipitate, take the filtrate, add sulfuric acid to adjust the pH to 8, and vacuum dry to obtain collagen powder.

[0035] Step 2: Preparation of UV-resistant retanning agent: 30 parts of manganese chloride, 60 parts of aluminum chloride, 5 parts of titanium chloride, 25 parts of 2,2-bithiophene-5,5-dicarboxylic acid, 15 parts of 2,3-pyrazine dicarboxylic acid, 20 parts of collagen powder, 3 parts of 2, (2'-hydroxy-3', 5'-di-tert-butylphenyl) benzotriazole (CAS: 3846-71-7), 2 parts of 2- (2'-hydroxy-4'aminophenyl) benzotriazole (CAS: 3234-33-1) are placed in a mixed solution of 150 parts of N, N-dimethylformamide, 10 parts of ethanol, 5 parts of water and 1 part of nitric acid, mixed evenly, reacted at 90°C for 36 hours, slowly lowered to room temperature, added 100 parts of N, N-dimethylformamide and 1 part of nitric acid, reacted at room temperature for 24 hours, and then filtered, repeatedly washed with N, N-dimethylformamide, and vacuum dried to obtain a UV-resistant retanning agent.

[0036] Step 3: Preparation of sulfonated UV-resistant retanning agent: 100 parts of UV-resistant retanning agent powder and 14 parts of sodium metabisulfite are dissolved in 265 parts of water, mixed evenly, reacted at 90°C for 3 hours, and then the product is vacuum dried to obtain a sulfonated transition metal coordinated polymer material retanning agent.

[0037] The aldehyde acid retanning agents obtained in Example 1, Example 2 and Example 3 were tested experimentally, and the experimental data obtained are shown in Table 1 below:

[0038] Table 1

[0039] Example 1 Example 2 Example 3 Particle size / nm 1949 1826 2265 Particle size distribution coefficient 0.240 0.362 0.436 Acid stability Stable without precipitation Stable without precipitation Stable without precipitation Neutral solution stability Stable without precipitation Stable without precipitation Stable without precipitation

[0040] Embodiment 4:

[0041] An application of a sulfonated UV-resistant retanning agent based on collagen, comprising a retanning process, a neutralization process, a filling process and a fatliquor process;

[0042] Retanning process: Based on the weight of wet blue leather, the drum temperature was controlled at 32°C, 50% water was added, 4% acid-resistant fatliquor (B1, Tankrom Chemicals), 2% fatty aldehyde (PF, Sima Chemicals) was added, and the drum was rotated for 20 minutes, and 7% chrome powder (Tankrom AB, Turkey), 3% sulfonated UV resistant retanning agent, rotate for 60 minutes, then add 1% sodium formate, rotate for 30 minutes, then add 0.8% baking soda in 3 times, rotate for 10, 10, 60 minutes, and drain.

[0043] Neutralization process: based on the weight of wet blue leather, control the drum temperature to 32°C, add 200% water, add 2% neutralizing tannin (A, Unitec, Italy), 1% sodium formate, rotate for 20 minutes, add 1% baking soda, 0.5% cyanamide carbonate, rotate for 60 minutes, wash with water and drain.

[0044] Filling process: based on the weight of wet blue leather, control the drum temperature to 32°C, add 70% of water, add 4% of amphoteric acrylic acid (D-37, Shanghai Kaifeng), 6% of anionic acrylic acid (TP340, Zhiqi Trading), and rotate for 20 minutes; then add 4% of dicyandiamide resin (1700, Hongfeng Polymer), 6% of melamine resin (1709, Hongfeng Polymer), 6% of tannin (ATO, Jinfeng Leather Chemical), 2% of dispersed tannin (TM, BASF Chemical), 2% of fatliquor (94S, Sima Chemical), and rotate for 60 minutes; then add 6% of tannin (ATO, Jinfeng Leather Chemical), 3% of synthetic tanning agent (RL, Derui Chemical), 3% of fatliquor (ZLN, Bisuo Chemical), and rotate for 120 minutes; finally add 3% of sulfonated UV-resistant retanning agent and rotate for 30 minutes.

[0045] Fatliquor process: based on the weight of wet blue leather, control the transfer temperature to 55°C, add 150% water, add 1% protein filler (FB, Sichuan Desaier), rotate for 30 minutes, add 3% synthetic fatliquor (505, Kekai Chemical), 3% lanolin (ZLN, Bisso Chemical), 3% lecithin (LC, Italy Unitco), 3% neat's foot oil (OPE, Italy Unitco), 3% sulfated oil (OB, Tompler Chemical), rotate for 180 minutes, finally add 2.5% formic acid in 4 times, rotate for 10, 10, 10, and 30 minutes respectively, and the crust leather can be obtained after drainage.

[0046] 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 method for preparing a sulfonated UV-resistant retanning agent based on collagen, characterized in that: The steps include: Step 1, take 100 parts of blue leather scraps, add 500 parts of deionized water, mix well, add 8-12 parts of alkali, react at 60-90°C for 3-6 hours, cool to room temperature, add 5-10 parts of calcium oxide, 1 part of polyaluminum chloride, and 1 part of polyacrylamide for flocculation precipitation, filter the precipitate, take the filtrate, add sulfuric acid to adjust the pH value to 6-8, and vacuum dry to obtain collagen powder; Step 2, taking 20-30 parts of manganese chloride, 40-65 parts of aluminum chloride, 0-15 parts of titanium chloride, 10-25 parts of 2,2-bithiophene-5,5-dicarboxylic acid, 0-15 parts of 2,3-pyrazine dicarboxylic acid, 20-40 parts of collagen powder, and 2-8 parts of benzotriazole organic matter, placing them in a mixed solution of 150 parts of N,N-dimethylformamide, 10 parts of ethanol, 5 parts of water and 1 part of nitric acid, mixing them evenly, reacting them at 75-90° C. for 36-72 hours, slowly lowering the temperature to room temperature, adding 100 parts of N,N-dimethylformamide and 1 part of nitric acid, reacting them at room temperature for 24 hours, and then filtering, repeatedly washing with N,N-dimethylformamide, and vacuum drying to obtain a UV-resistant retanning agent; Step 3, preparation of sulfonated UV-resistant retanning agent: 100 parts of UV-resistant retanning agent powder and 5-15 parts of sodium pyrosulfite are dissolved in 200-300 parts of water, mixed evenly, reacted at 80-100° C. for 3 hours, and then the product is vacuum dried to obtain a sulfonated UV-resistant retanning agent.

2. The method for preparing a sulfonated UV-resistant retanning agent based on collagen according to claim 1, characterized in that: The alkali is one or more of sodium hydroxide, potassium hydroxide and calcium oxide.

3. The method for preparing a sulfonated UV-resistant retanning agent based on collagen according to claim 1, characterized in that: The benzotriazole-based organic compound is one or more of 2, (2'-hydroxy-5'-methylphenyl) benzotriazole, 2, (2'-hydroxy-3', 5'-di-tert-butylphenyl) benzotriazole, and 2- (2'-hydroxy-4'aminophenyl) benzotriazole.

4. The use of a sulfonated UV-resistant retanning agent based on collagen as described in any one of claims 1 to 3, characterized in that: At least including the retanning process and the filling process; The specific steps of the retanning process are: based on the weight of the wet blue leather, controlling the drum temperature to be 30-35° C., adding 50-100% of water, adding 2-4% of an acid-resistant fatliquor, 0-3% of aliphatic aldehyde, rotating for 20 minutes, adding 4-6% of chrome powder, 1-3% of a sulfonated UV-resistant retanning agent, rotating for 60 minutes, and then adding 1% of sodium formate, rotating for 30 minutes, and then adding 0.8% of baking soda in three times, rotating for 10, 10, and 60 minutes; The specific steps of the filling process are: based on the weight of the wet blue leather, the drum temperature is controlled to be 30-35°C, 50-100% of water, 2-4% of amphoteric acrylic acid, 4-8% of anionic acrylic acid are added, and the drum is rotated for 20-40 minutes; then 4-6% of dicyandiamide resin, 4-6% of melamine resin, 4-6% of tannin extract, 2% of dispersed tannin, 1-3% of fatliquor are added, and the drum is rotated for 40-60 minutes; then 4-6% of tannin extract, 2-4% of synthetic tanning agent, 1-3% of fatliquor are added, and the drum is rotated for 120 minutes; finally 1-3% of sulfonated UV-resistant retanning agent is added, and the drum is rotated for 20-60 minutes.