A method for preparing aldehyde acid retanning agent based on seawater tanning and high-end sofa leather

Abstract

The present invention relates to a method for preparing an aldehyde acid retanning agent based on seawater leather and a high-end sofa leather, wherein pentaerythritol and mellitic acid are mixed uniformly, concentrated sulfuric acid is added dropwise, and excess mellitic acid and hydroxyl-containing small molecule glycol acetal are removed by rotary evaporation, and the temperature is slowly raised to 70-100 DEG C after mixing uniformly, concentrated sulfuric acid is added dropwise, and finally cooled to room temperature to obtain an aldehyde acid retanning agent. The aldehyde acid retanning agent based on seawater leather of the present invention has a relatively suitable particle size and dispersibility, can well promote the adsorption and binding of skin collagen fibers to Cr (III), and can well promote the adsorption and binding of skin collagen fibers to subsequent retanning, filling, and dyeing materials.

Description

Technical Field

[0001] The invention relates to the technical field of leather making, in particular to an aldehyde acid retanning agent based on seawater leather making and a preparation method of high-end sofa leather. Background Art

[0002] Blue wet leather tanned with seawater instead of tap water has the characteristics of clear grain, firm and fleshy leather body, but due to the complex composition of seawater, in addition to a large number of sodium ions and chloride ions, there are also many metal ions with coordination ability, such as Al (III), Co (II), Ni (II), etc., and there are also many organic substances in the water, such as humic acid, chitin, alginic acid, etc. These metal ions and organic substances attach to the skin collagen fibers, cross-linking the skin collagen fibers, making the skin collagen fibers more compact, but this cross-linking also hinders the penetration and combination of subsequent retanning, dyeing, and fat-liquoring materials to a certain extent. However, if these substances are removed by chemical means, it will violate the original intention of replacing tap water with seawater to reduce water resource utilization, and it will also cause great loss of leather performance. Therefore, if these substances are fully retained, further activating the active functional groups on the skin collagen fibers and promoting their combination with subsequent retanning, dyeing, and fat-liquoring materials has become a major research problem. Summary of the invention

[0003] The present invention provides a aldehyde acid retanning agent based on seawater leather making and a preparation method of high-end sofa leather, so as to solve the problem that metal ions and organic matter in seawater adhere to skin collagen fibers and cross-link skin collagen fibers, and this cross-linking also hinders the penetration and combination of subsequent retanning, dyeing and fat-liquoring materials to a certain extent. The large number of carboxyl groups carried by the aldehyde acid retanning agent itself can provide binding points for the metal tanning agent used in the subsequent retanning, further promote the adsorption of chromium by the skin collagen fibers, and the cationic center provided by chromium can further promote the adsorption and combination of subsequent filling, dyeing and fat-liquoring materials, which is beneficial to improve the physical and mechanical properties and sensory properties of the leather.

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

[0005] A preparation method of an aldehyde acid retanning agent based on seawater leather making comprises the following steps: taking 100 parts of pentaerythritol and 450-600 parts of mellitic acid and mixing them uniformly, slowly raising the temperature to 60-90 DEG C under nitrogen protection, dropwise adding 5-20 parts of concentrated sulfuric acid within 1 hour, then continuing to keep the temperature for 1-5 hours, slowly reducing the temperature to room temperature, then removing excess mellitic acid by rotary evaporation, adding 220-300 parts of hydroxyl-containing small molecular ethylene glycol acetal, slowly raising the temperature to 70-100 DEG C after uniform mixing, dropwise adding 8-30 parts of concentrated sulfuric acid within 1 hour, then continuing to keep the temperature for 3-8 hours, slowly reducing the temperature to 40-50 DEG C, adding 500-650 parts of water, adjusting the pH value to 3.0-4.5 with sulfuric acid, keeping the temperature constant for 1-3 hours, and finally cooling to room temperature to prepare the aldehyde acid retanning agent.

[0006] In a further improvement, the above-mentioned ethylene glycol acetal contains at least 1,3-dioxolane-2-methanol, and the ethylene glycol acetal may contain one or more of 1,3-dioxolane-2-ethanol, 2-[2-(1,3-dioxolane-2-yl)ethoxy]ethanol, and 2-(1,3-dioxolane-2-yl)propane-1,3-diol.

[0007] A method for preparing high-grade sofa leather based on seawater tanning, comprising at least a neutralization step and a retanning step;

[0008] Neutralization process: based on the weight of the wet blue leather, control the drum temperature to 35-40°C, add 2-4% neutralized tannin, 1-2% sodium formate, rotate for 20 minutes, add 0.5-1.5% baking soda, 0.5-1.5% sodium bicarbonate, rotate for 60 minutes, add 1-3% aldehyde acid retanning agent based on seawater tanning, rotate for 40 minutes, drain, add 200% water, and rinse;

[0009] Retanning process: based on the weight of wet blue leather, control the drum temperature at 30-35℃, add 75-150% water, add 2-4% aldehyde acid retanning agent based on seawater leather, 1-3% lecithin fatliquor, 2-4% acid-resistant acrylic resin retanning agent, rotate for 30-60 minutes, then add 2-4% aldehyde acid retanning agent based on seawater leather, 2-4% synthetic tanning agent, 2-4% protein filler, rotate for 60-120 minutes, add 100-150% water, Add 1-2% formic acid three times, rotate for 10, 10 and 20 minutes respectively, add 2-4% aldehyde acid retanning agent based on seawater leather, rotate for 20 minutes, add 4-6% chrome tanning agent, 2-4% aluminum-containing tanning agent, 1-3% acid-resistant fatliquor, rotate for 120-180 minutes, then add 1.5-2.5% sodium formate, rotate for 20 minutes, add 1-2% baking soda, rotate for 60 minutes, add 1-2% ammonium bicarbonate, and rotate for 60 minutes.

[0010] 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:

[0011] 1. Pentaerythritol has four hydroxyl groups on the molecule, and theoretically can form a primary hyperbranched structure with up to four mellitic acid molecules. Since the four hydroxyl groups of pentaerythritol are relatively far apart, one pentaerythritol molecule can be grafted with 3 to 4 mellitic acid molecules at the same time. Only primary hyperbranching has a larger molecular structure, but the structure of all carboxyl groups is only hydrogen-bonded with skin collagen. Under the premise that the active sites of skin collagen fibers have been basically consumed by seawater and chromium powder during tanning, the reaction activity of mellitic acid grafted pentaerythritol with skin collagen is weak. Analysis of the state of skin collagen fibers after tanning shows that a large number of carboxyl groups are occupied by chromium powder and metal ions, while amino groups are only occupied by a relatively small number, so more active sites can be introduced by activating amino groups. Amino groups and carbonyl groups can undergo addition-elimination reactions at room temperature, so carbonyl groups are an ideal activated functional group. A large number of carboxyl groups can provide binding sites for metal tanning agents used in subsequent retanning, further promoting the adsorption of chromium by leather collagen fibers. The cationic center provided by chromium can further promote the adsorption and binding of subsequent filling, dyeing, and greasing materials, which is beneficial to improving the physical, mechanical and sensory properties of leather.

[0012] 2. The aldehyde acid retanning agent based on seawater leather has a more suitable particle size and dispersion performance, with a particle size of 600-1000nm and a particle size distribution coefficient of 0.200-0.450. It also has good negative charge, and the zeta potential is ≤-30mV.

[0013] 3. The aldehyde acid retanning agent based on seawater leather can effectively promote the adsorption and binding of Cr(III) by leather collagen fibers. Compared with the case without the use of aldehyde acid retanning agent, the total chromium content of leather can be increased by about 20%, the total chromium in wastewater can be reduced by about 60%, and the COD in the waste liquid can be reduced by about 10%.

[0014] 4. The aldehyde acid retanning agent based on seawater leather can effectively promote the adsorption and bonding of leather collagen fibers to subsequent retanning, filling and dyeing materials. The shrinkage temperature of the crust leather is ≥90℃, the tear force is ≥50N, the crack height is ≥7mm, the bursting strength is ≥300N, and the odor is ≤level 3. DETAILED DESCRIPTION

[0015] Embodiment 1:

[0016] A method for preparing an aldehyde acid retanning agent based on seawater leather making comprises the following steps: taking 100 parts of pentaerythritol and 450 parts of mellitic acid and mixing them uniformly, slowly raising the temperature to 85°C under nitrogen protection, adding 6 parts of concentrated sulfuric acid dropwise within 1 hour, then continuing to keep the temperature for 2 hours, slowly reducing the temperature to room temperature, then removing excess mellitic acid by rotary evaporation, adding 220 parts of 1,3-dioxolane-2-methanol, slowly raising the temperature to 95°C after mixing uniformly, adding 12 parts of concentrated sulfuric acid dropwise within 1 hour, then continuing to keep the temperature for 5 hours, slowly reducing the temperature to 45°C, adding 625 parts of water, adjusting the pH value to 3.0 with sulfuric acid, keeping the temperature constant for 3 hours, and finally cooling to room temperature to prepare the aldehyde acid retanning agent.

[0017] Embodiment 2:

[0018] A preparation method of an aldehyde acid retanning agent based on seawater leather making comprises the following steps: taking 100 parts of pentaerythritol and 500 parts of mellitic acid and mixing them evenly, slowly raising the temperature to 75°C under nitrogen protection, dropwise adding 10 parts of concentrated sulfuric acid within 1 hour, then continuing to keep the temperature for 3 hours, slowly reducing the temperature to room temperature, then removing excess mellitic acid by rotary evaporation, adding 100 parts of 1,3-dioxolane-2-ethanol and 150 parts of 1,3-dioxolane-2-methanol, slowly raising the temperature to 85°C after mixing evenly, dropwise adding 20 parts of concentrated sulfuric acid within 1 hour, then continuing to keep the temperature for 6 hours, slowly reducing the temperature to 50°C, adding 580 parts of water, adjusting the pH value to 4.0 with sulfuric acid, keeping the temperature constant for 2 hours, and finally cooling to room temperature to prepare the aldehyde acid retanning agent based on seawater leather making.

[0019] Embodiment 3:

[0020] A method for preparing an aldehyde retanning agent based on seawater leather making comprises the following steps: taking 100 parts of pentaerythritol and 600 parts of mellitic acid and mixing them evenly, slowly raising the temperature to 65°C under nitrogen protection, dropwise adding 18 parts of concentrated sulfuric acid within 1 hour, then continuing to keep the temperature for 4 hours, slowly lowering the temperature to room temperature, then removing excess mellitic acid by rotary evaporation, adding 100 parts of 2-[2-(1,3-dioxolane-2-yl)ethoxy]ethoxy Alcohol, 150 parts of 2-(1,3-dioxolane-2-yl)propane-1,3-diol, and 50 parts of 1,3-dioxolane-2-methanol, mix well, slowly raise the temperature to 75°C, add 30 parts of concentrated sulfuric acid dropwise within 1 hour, and then continue to keep warm for 7 hours, slowly lower the temperature to 40°C, add 500 parts of water, adjust the pH value to 4.5 with sulfuric acid, keep the temperature constant for 1 hour, and finally cool to room temperature to obtain an aldehyde tanning agent based on seawater leather.

[0021] 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:

[0022] Table 1

[0023]

[0024] Embodiment 4:

[0025] A method for preparing high-grade sofa leather based on seawater tanning, comprising at least a neutralization step, a retanning step, a filling step, and a fatliquoring step, wherein the aldehyde retanning agent prepared in the above embodiment 1 is added to the neutralization step;

[0026] Neutralization process: based on the weight of the wet blue leather, control the drum temperature to 36°C, add 3% neutralizing tannin (NSL, Barts Chemical), 1% sodium formate, rotate for 20 minutes, add 1.2% baking soda, 0.8% sodium bicarbonate, rotate for 60 minutes, add 2% aldehyde acid retanning agent based on seawater tanning, rotate for 40 minutes, drain, add 200% water, and rinse.

[0027] Retanning process: based on the weight of wet blue leather, the drum temperature was controlled at 32°C, 100% of water was added, 3% aldehyde acid retanning agent based on seawater leather, 2% lecithin fatliquor (NLM, Stahl), 4% acid-resistant acrylic resin retanning agent (1084, Lanxess Chemical) were added, and the mixture was rotated for 30 minutes. Then, 3% aldehyde acid retanning agent based on seawater leather, 3% synthetic tanning agent (FO, BASF), 3% protein filler (FB, Desail Chemical) were added, and the mixture was rotated for 60 minutes. 125% of water was added, 1.4% formic acid was added three times, and the mixture was rotated for 10, 10 and 20 minutes respectively. 3% aldehyde acid retanning agent based on seawater leather was added, and the mixture was rotated for 20 minutes. 4% chrome tanning agent (Tankrom AB, Turkey), 3% aluminum-containing tanning agent (CAN, Desail Chemical), 2% acid-resistant fatliquor (B1, Temple Chemical), rotate for 120 minutes, then add 2% sodium formate, rotate for 20 minutes, add 2% baking soda, rotate for 60 minutes, add 2% ammonium bicarbonate, and rotate for 60 minutes.

[0028] Filling process: based on the weight of wet blue leather, control the drum temperature to 32°C, add 70% of water, add 4% amphoteric acrylic acid (TGR, Derui Chemical), 6% anionic acrylic acid (TP340, Apa Chemical), 2% fatliquor (94S, Sima Chemical) and rotate for 20 minutes; then add 3% dicyandiamide resin (R19, Tiger Chemical), 3% melamine resin (DLF, BASF Chemical), 6% tannin extract (TARA, Shihua Chemical), 2% disperse tannin (TM, BASF Chemical), 2% fatliquor (94S, Sima Chemical) and rotate for 60 minutes; then add 6% tannin extract (ATO, Jinfeng Leather Chemical), 3% synthetic tanning agent (RL, Derui Chemical), 3% fatliquor (ZLN, Kekai Chemical) and rotate for 120 minutes.

[0029] Fatting process: based on the weight of wet blue leather, the transfer temperature is controlled to be 55°C, 150% of water is added, 3% synthetic fatliquor (505, Kekai Chemical), 3% lanolin (ZLN, Kekai Chemical), 3% lecithin (BA, Sima Chemical) are added, and rotated for 60 minutes, 3% neat's foot oil (OPE, Italy Unitco), 3% sulfated oil (DB, Tompler Chemical), 3% silicone waterproof oil (S33, Zhejiang Honglin Leather Chemical) are rotated for 180 minutes, and finally 2.5% formic acid is added in 4 times, and rotated for 10, 10, 10, and 30 minutes respectively to obtain crust leather.

[0030] Embodiment 5:

[0031] The preparation method of high-grade sofa leather based on seawater tanning in this embodiment is basically the same as the preparation method in Example 4, except that in this embodiment, the aldehyde acid retanning agent prepared in the above Example 2 is added in the neutralization process.

[0032] Embodiment 6:

[0033] The preparation method of high-grade sofa leather based on seawater tanning in this embodiment is basically the same as the preparation method in Example 4, except that in this embodiment, the aldehyde acid retanning agent prepared in the above Example 3 is added in the neutralization process.

[0034] Comparative Example:

[0035] The preparation method of the comparative example is basically the same as that of Example 4, except that no aldehyde acid retanning agent is added in the comparative example.

[0036] The crust leather obtained in the comparative example, embodiment 4, embodiment 5 and embodiment 6 was tested, and the experimental data obtained are shown in the following table 2:

[0037] Table 2

[0038]

[0039] 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 an aldehyde acid retanning agent based on seawater leather making, characterized in that: The method comprises the following steps: taking 100 parts of pentaerythritol and 450-600 parts of mellitic acid and mixing them uniformly; under nitrogen protection, slowly raising the temperature to 60-90°C; adding 5-20 parts of concentrated sulfuric acid dropwise within 1 hour, then keeping the temperature for 1-5 hours, slowly lowering the temperature to room temperature, then removing excess mellitic acid by rotary evaporation; adding 220-300 parts of hydroxyl-containing small molecular ethylene glycol acetal; after mixing uniformly, slowly raising the temperature to 70-100°C; adding 8-30 parts of concentrated sulfuric acid dropwise within 1 hour, then keeping the temperature for 3-8 hours, slowly lowering the temperature to 40-50°C; adding 500-650 parts of water; adjusting the pH value to 3.0-4.5 with sulfuric acid; keeping the temperature constant for 1-3 hours; and finally cooling to room temperature to obtain an aldehyde acid retanning agent, wherein the ethylene glycol acetal is 1,3-dioxolane-2-methanol.

2. The method for preparing an aldehyde acid retanning agent based on seawater leather making according to claim 1, characterized in that: The ethylene glycol acetal further contains 1,3-dioxolane-2-ethanol.

3. A method for preparing high-grade sofa leather based on seawater tanning, characterized in that: The method comprises at least a neutralization step and a retanning step, wherein the aldehyde acid retanning agent as claimed in claim 1 or 2 is added in the neutralization step; Neutralization process: based on the weight of wet blue leather, control the drum temperature to 35-40°C, add 2-4% neutralized tannin, 1-2% sodium formate, rotate for 20 minutes, add 0.5-1.5% baking soda, 0.5-1.5% sodium bicarbonate, rotate for 60 minutes, add 1-3% aldehyde acid retanning agent based on seawater tanning, rotate for 40 minutes, drain, add 200% water, and rinse; Retanning process: based on the weight of wet blue leather, control the drum temperature to 30-35°C, add 75-150% water, add 2-4% aldehyde acid retanning agent based on seawater leather, 1-3% lecithin fatliquor, 2-4% acid-resistant acrylic resin retanning agent, rotate for 30-60 minutes, then add 2-4% aldehyde acid retanning agent based on seawater leather, 2-4% synthetic tanning agent, 2-4% protein filler, rotate for 60-120 minutes, add 100-150% water, separate Add 1-2% formic acid three times, rotate for 10 minutes, 10 minutes and 20 minutes respectively, add 2-4% aldehyde acid retanning agent based on seawater leather, rotate for 20 minutes, add 4-6% chrome tanning agent, 2-4% aluminum-containing tanning agent, 1-3% acid-resistant fatliquor, rotate for 120-180 minutes, then add 1.5-2.5% sodium formate, rotate for 20 minutes, add 1-2% baking soda, rotate for 60 minutes, add 1-2% ammonium bicarbonate, rotate for 60 minutes.

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