Strong-color-fixation and environment-friendly synthetic aluminum tanning agent and preparation method and application thereof

Abstract

The invention discloses a strong-color-fixation environment-friendly synthetic aluminum tanning agent and a preparation method and application thereof, and the preparation method comprises the following steps: S1, adding 30 parts of deionized water into a reactor under the stirring condition; s2, cooling water is started, the temperature is maintained to be 55 DEG C or below, 20 parts of sodium metaaluminate is slowly added step by step, and after adding is completed, the temperature is maintained to be 50-55 DEG C, and stirring is conducted for 60 min; s3, 31-33 parts of formic acid and 20-23 parts of glycolic acid are added into another reaction kettle, and stirring is started; s4, cooling water is started, the temperature is maintained to be 40 DEG C or below, the solution obtained in S2 is dropped into the reaction kettle in S3, and the time is controlled to be 90-120 min; and S5, after dropwise adding the solution in the S2, stopping cooling, starting heating, maintaining the temperature at 80-90 DEG C, and reacting for 2-5 hours. And cooling to obtain the colorless transparent synthetic aluminum tanning agent with the pH value of 3.0-4.0 and the solid content of 50.0-55.0%. The environment-friendly synthetic aluminum tanning agent prepared by the method can endow leather with good softness, filling property and color fixing effect.

Description

Technical Field

[0001] The present invention relates to the field of preparation of aluminum tanning agents, and more specifically, to a strong color-fixing and environmentally friendly synthetic aluminum tanning agent, its preparation method and application. Background Art

[0002] Tanning is a very important process in the processing of leather products. It can endow leather with excellent thermal stability, increase the shrinkage temperature, enhance the color-fixing effect, and also give leather a comfortable hand feeling, increase softness and toughness. Different tanning agents are used for tanning to produce different tanning methods, and the most widely used tanning method in the current leather industry is chrome tanning. However, in the traditional chrome tanning process, a large amount of chromium sulfate complex is required, and the absorption of raw hides for chrome tanning agents is only about 70%. This results in extremely high concentrations of chromium in the wastewater generated after chrome tanning, which will cause great pollution to the environment and greatly damage the ecological environment. And treating the generated sewage will also greatly increase the costs of enterprises. Therefore, in order to reduce the environmental pollution of the leather industry while reducing production costs and ensuring the sustainable development of the leather industry, chromium-free tanning agents that can replace chrome tanning and corresponding tanning technologies are extremely important. And aluminum tanning agents are one of the focuses of research. Summary of the Invention

[0003] The purpose of the present invention is to provide a strong color-fixing and environmentally friendly synthetic aluminum tanning agent, its preparation method and application. The aluminum tanning agent prepared by this method has good acid resistance, alkali resistance and salt resistance, can endow leather with excellent thermal stability, a relatively high shrinkage temperature, a comfortable hand feeling and a very strong color-fixing effect, and moreover, it will not produce a large amount of harmful waste liquid like the chrome tanning process, and is more environmentally friendly, so as to solve the technical problems existing in the above background art.

[0004] To achieve the above purpose, the present invention provides a strong color-fixing and environmentally friendly synthetic aluminum tanning agent, and the raw materials by weight include: 31 - 33 parts of formic acid, 20 - 23 parts of glycolic acid, 20 parts of sodium meta-aluminate, and 30 parts of water.

[0005] The present invention also provides a preparation method of a strong color-fixing and environmentally friendly synthetic aluminum tanning agent, which includes the following steps:

[0006] S1: Start stirring, and add 30 parts of water into the reactor;

[0007] S2: Start the cooling water, maintain the temperature below 55°C, slowly add 20 parts of sodium meta-aluminate step by step. After adding, maintain the temperature at 50 - 55°C and stir for 60 min;

[0008] S3: Add 31 - 33 parts of formic acid and 20 - 23 parts of glycolic acid into another reaction kettle, and start stirring;

[0009] S4: Turn on the cooling water and maintain the temperature below 40°C. Drop the solution obtained in S2 into the reaction kettle in S3, and control the time within 90 - 120 min.

[0010] S5: After dropping the solution in S2 completely, turn off the cooling and turn on the heating. Maintain the temperature at 80 - 90°C and react for 2 - 5 h. After cooling, a colorless and transparent synthetic aluminum tanning agent with a pH of 3.0 - 4.0 and a solid content of 50.0 - 55.0% can be obtained.

[0011] The present invention also provides an application of the above-mentioned aluminum tanning agent, which is used for leather fatliquoring and color fixation.

[0012] The beneficial effects of the technical solution of the present invention are as follows:

[0013] 1. The strong color-fixing and environmentally friendly synthetic aluminum tanning agent prepared by the present invention can endow leather with excellent thermal stability, a relatively high shrinkage temperature, a comfortable hand feeling and an extremely strong color-fixing effect, and is environmentally friendly.

[0014] 2. The aluminum tanning agent of the present invention uses glycolic acid, formic acid and sodium meta-aluminate as synthetic raw materials. Among aluminum tanning agents, when acetate and formate are used as ligands, the stability of leather after tanning is the best, and the shrinkage stability can reach 74 - 78°C; while the present invention uses glycolic acid as the basic ligand and introduces a large number of hydroxyl groups, which can effectively reduce the bonding effect of leather fibers after tanning, bringing good looseness and moisturizing to the leather; moreover, due to the large number of hydroxyl groups carried by the aluminum tanning agent, the color-fixing effect of the leather after tanning is significantly stronger than that of common tanning agent products. Detailed Embodiments

[0015] The present invention will be further described in detail below in conjunction with the specific embodiments. The embodiments of the present invention are given for the convenience of illustration and description, and are not exhaustive or limit the present invention to the disclosed form. Many modifications and variations are obvious to those of ordinary skill in the art. The embodiments are selected and described to better illustrate the principles and practical applications of the present invention, and enable those of ordinary skill in the art to understand the present invention and thus design various embodiments with various modifications suitable for specific purposes.

[0016] The raw materials of the strong color-fixing and environmentally friendly synthetic aluminum tanning agent according to the present invention may include, by weight: 31 - 33 parts of formic acid, 20 - 23 parts of glycolic acid, 20 parts of sodium meta-aluminate, and 30 parts of water.

[0017] The preparation method of the strong color-fixing and environmentally friendly synthetic aluminum tanning agent according to the present invention may include the following steps:

[0018] S1: Turn on the stirring and add 30 parts of water to the reactor.

[0019] S2: Turn on the cooling water, maintain the temperature below 55°C, slowly add 20 parts of sodium aluminate in portions. After adding, maintain the temperature at 50 - 55°C and stir for 60 min;

[0020] S3: Add 31 - 33 parts of formic acid and 20 - 23 parts of glycolic acid to another reactor, and turn on the stirring;

[0021] S4: Turn on the cooling water, maintain the temperature below 40°C, and drip the solution obtained in S2 into the reactor of S3, with the time controlled within 90 - 120 min;

[0022] S5: After the solution in S2 is completely dripped, turn off the cooling, turn on the heating, maintain the temperature at 80 - 90°C, and react for 2 - 5 h. After cooling, a colorless and transparent synthetic aluminum tanning agent with a pH of 3.0 - 4.0 and a solid content of 50.0 - 55.0% can be obtained.

[0023] The aluminum tanning agent according to the present invention can be used for leather fatliquoring and color fixation.

[0024] In the preparation method of the strong color-fixing and environment-friendly synthetic aluminum tanning agent according to the present invention, first dissolve sodium aluminate into a suitable solution state; then prepare suitable acid solutions with different groups, and then drip the sodium aluminate solution into the acid solution at a certain rate for reaction until it becomes transparent, and the finished product of the aluminum tanning agent can be obtained. A large amount of glycolic acid with hydroxyl groups is used in the aluminum tanning agent of the present invention to react with sodium aluminate, which can endow the leather with good and comfortable hand feeling performance and extremely strong color-fixing ability. Using sodium aluminate as the raw material of the tanning agent can not only provide good thermal stability and shrinkage rate for the leather, but also will not pollute the environment, reduce the cost of the enterprise in treating wastewater, and meet the requirements of sustainable development.

[0025] Hereinafter, in combination with specific embodiments, the strong color-fixing and environment-friendly synthetic aluminum tanning agent of the present invention, its preparation method and application will be specifically described. The main raw materials and equipment used: Unless otherwise specified, the raw materials and equipment in each embodiment and comparative example are the same; the materials without specifying the specific model or type are from market procurement or common same models that can be obtained through usual channels, and no specific restrictions are made..

[0026] Example 1

[0027] The preparation method of the strong color-fixing and environment-friendly synthetic aluminum tanning agent provided in this example includes the following steps:

[0028] S1: Turn on the stirring, and add 30 parts of water to the reactor;

[0029] S2: Turn on the cooling water, maintain the temperature below 55°C, slowly add 20 parts of sodium aluminate in portions. After adding, maintain the temperature at 50 - 55°C and stir for 60 min;

[0030] S3: Add 31 parts of formic acid and 23 parts of glycolic acid into another reactor, and start stirring.

[0031] S4: Turn on the cooling water and maintain the temperature below 40°C. Drop the solution obtained in S2 into the reactor in S3, and control the dropping time within 90 - 120 minutes.

[0032] S5: After dropping the solution in S2 completely, turn off the cooling and turn on the heating. Maintain the temperature at 82°C and react for 4.5 hours. After cooling, a colorless and transparent strong color-fixing and environmentally friendly synthetic aluminum tanning agent with a pH of 3.62 and a solid content of 53.5% can be obtained.

[0033] Example 2

[0034] The preparation method of the strong color-fixing and environmentally friendly synthetic aluminum tanning agent provided in this example includes the following steps:

[0035] S1: Start stirring and add 30 parts of water into the reactor.

[0036] S2: Turn on the cooling water and maintain the temperature below 55°C. Slowly add 20 parts of sodium metaaluminate in portions. After adding, maintain the temperature at 50 - 55°C and stir for 60 minutes.

[0037] S3: Add 32 parts of formic acid and 22 parts of glycolic acid into another reactor, and start stirring.

[0038] S4: Turn on the cooling water and maintain the temperature below 40°C. Drop the solution obtained in S2 into the reactor in S3, and control the dropping time within 90 - 120 minutes.

[0039] S5: After dropping the solution in S2 completely, turn off the cooling and turn on the heating. Maintain the temperature at 85°C and react for 3.5 hours. After cooling, a colorless and transparent strong color-fixing and environmentally friendly synthetic aluminum tanning agent with a pH of 3.39 and a solid content of 52.9% can be obtained.

[0040] Example 3

[0041] The preparation method of the strong color-fixing and environmentally friendly synthetic aluminum tanning agent provided in this example includes the following steps:

[0042] S1: Start stirring and add 30 parts of water into the reactor.

[0043] S2: Turn on the cooling water and maintain the temperature below 55°C. Slowly add 20 parts of sodium metaaluminate in portions. After adding, maintain the temperature at 50 - 55°C and stir for 60 minutes.

[0044] S3: Add 33 parts of formic acid and 20 parts of glycolic acid into another reactor, and start stirring.

[0045] S4: Turn on the cooling water, maintain the temperature below 40°C, and drip the solution obtained in S2 into the reaction kettle in S3, with the time controlled within 90 - 120 min;

[0046] S5: After dripping the solution in S2 is completed, turn off the cooling, turn on the heating, maintain the temperature at 88°C, and react for 2.5 h; After cooling, a colorless and transparent strong color-fixing and environmentally friendly synthetic aluminum tanning agent with a pH of 3.62 and a solid content of 53.8% can be obtained.

[0047] Example 4

[0048] The preparation method of the strong color-fixing and environmentally friendly synthetic aluminum tanning agent provided in this example includes the following steps:

[0049] S1: Turn on the stirring, and add 30 parts of water into the reactor;

[0050] S2: Turn on the cooling water, maintain the temperature below 55°C, slowly add 20 parts of sodium metaaluminate step by step. After adding, maintain the temperature at 50 - 55°C and stir for 60 min;

[0051] S3: Add 31 parts of formic acid and 23 parts of glycolic acid into another reaction kettle, and turn on the stirring;

[0052] S4: Turn on the cooling water, maintain the temperature below 40°C, and drip the solution obtained in S2 into the reaction kettle in S3, with the time controlled within 90 - 120 min;

[0053] S5: After dripping the solution in S2 is completed, turn off the cooling, turn on the heating, maintain the temperature at 80°C, and react for 5 h; After cooling, a colorless and transparent synthetic aluminum tanning agent with a pH of 3.4 and a solid content of 53.5% can be obtained.

[0054] Comparative Example 1

[0055] The preparation method of the aluminum tanning agent includes the following steps:

[0056] S1: Turn on the stirring, and add 30 parts of water into the reactor;

[0057] S2: Turn on the cooling water, maintain the temperature below 55°C, slowly add 20 parts of sodium metaaluminate step by step. After adding, maintain the temperature at 50 - 55°C and stir for 60 min;

[0058] S3: Add 33 parts of formic acid and 23 parts of citric acid into another reaction kettle, and turn on the stirring;

[0059] S4: Turn on the cooling water, maintain the temperature below 40°C, and drip the solution obtained in S2 into the reaction kettle in S3, with the time controlled within 90 - 120 min;

[0060] S5: After the addition of the solution in S2 is completed, turn off the cooling, turn on the heating, maintain the temperature at 85 °C, and react for 3.5 h; after cooling, a colorless and transparent synthetic aluminum tanning agent with a pH of 3.5 and a solid content of 53.8% can be obtained.

[0061] Comparative Example 2

[0062] The preparation method of the aluminum tanning agent includes the following steps:

[0063] S1: Turn on the stirring, and add 30 parts of water to the reactor;

[0064] S2: Turn on the cooling water, maintain the temperature below 55 °C, slowly add 20 parts of sodium metaaluminate in portions, and after the addition, maintain the temperature at 50 - 55 °C and stir for 60 min;

[0065] S3: Add 32 parts of formic acid and 23 parts of oxalic acid to another reaction kettle, and turn on the stirring;

[0066] S4: Turn on the cooling water, maintain the temperature below 40 °C, and drip the solution obtained in S2 into the reaction kettle of S3, and control the time within 90 - 120 min;

[0067] S5: After the addition of the solution in S2 is completed, turn off the cooling, turn on the heating, maintain the temperature at 85 °C, and react for 3.5 h; after cooling, a colorless and transparent synthetic aluminum tanning agent with a pH of 3.6 and a solid content of 53.9% can be obtained.

[0068] Comparative Example 3

[0069] The preparation method of the aluminum tanning agent includes the following steps:

[0070] S1: Turn on the stirring, and add 30 parts of water to the reactor;

[0071] S2: Turn on the cooling water, maintain the temperature below 55 °C, slowly add 20 parts of sodium metaaluminate in portions, and after the addition, maintain the temperature at 50 - 55 °C and stir for 60 min;

[0072] S3: Add 32 parts of formic acid and 23 parts of glyoxylic acid to another reaction kettle, and turn on the stirring;

[0073] S4: Turn on the cooling water, maintain the temperature below 40 °C, and drip the solution obtained in S2 into the reaction kettle of S3, and control the time within 90 - 120 min;

[0074] S5: After the addition of the solution in S2 is completed, turn off the cooling, turn on the heating, maintain the temperature at 85 °C, and react for 3.5 h; after cooling, a light yellow transparent synthetic aluminum tanning agent with a pH of 3.9 and a solid content of 53.6% can be obtained.

[0075] Comparative Example 4

[0076] The preparation method of the aluminum tanning agent includes the following steps:

[0077] S1: Start stirring and add 30 parts of water into the reactor;

[0078] S2: Start the cooling water, maintain the temperature below 55°C, slowly add 20 parts of sodium metaaluminate in portions. After adding, maintain the temperature at 50 - 55°C and stir for 60 min;

[0079] S3: Add 31 parts of formic acid and 23 parts of tartaric acid into another reaction kettle, and start stirring;

[0080] S4: Start the cooling water, maintain the temperature below 40°C, and drip the solution obtained in S2 into the reaction kettle of S3, with the time controlled within 90 - 120 min;

[0081] S5: After dripping the solution in S2 completely, turn off the cooling, start heating, maintain the temperature at 85°C, and react for 3.5 h; After cooling, a colorless and transparent synthetic aluminum tanning agent with a pH of 3.8 and a solid content of 53.7% can be obtained.

[0082] Performance test

[0083] Take the aluminum tanning agents prepared in Examples 1 - 4 and Comparative Examples 1 - 4 and the commercially available chrome tanning agent SEACRYTAN GM on the market as samples, and conduct tanning agent, fatliquoring, and color fixation applications on sheepskin. The specific process is as follows:

[0084]

[0085]

[0086] Take the commercially available tanning agent SEACRYTAN GM on the market and the aluminum tanning agents prepared in Examples 1 - 4 and Comparative Examples 1 - 4 of the present invention to conduct tanning and fatliquoring applications on sheepskin, conduct routine tests, and make sensory evaluations of the leather for tanning agent, fatliquoring, and color fixation. The test method for the solid content follows GB T2793 - 1995, and the sensory performance (filling property, softness, moisturizing property, color fixation effect) evaluation follows GB T16799 - 2018 and GB T39371 - 2020. Experts score the sensory performance, with the score ranging from 1 - 10 points (10 points being the best). The performance test results are shown in Table 1.

[0087] Table 1 Performance test results

[0088]

[0089]

[0090] It can be seen from the test result data in Table 1 that after the application test on leather, the sensory properties such as filling property, softness, moisturizing property and color fixing effect of the aluminum tanning agents prepared in Examples 1-4 are better than those of SEACRYTAN GM and Comparative Examples 1-4; in terms of leather hand feeling, the filling property is better than that of SEACRYTAN GM and Comparative Examples 1-4, and the softness and moisturizing property are higher than those of the comparative examples; while in terms of color fixing effect, it is far better than the comparative examples.

[0091] Compared with SEACRYTAN GM and Comparative Examples 1-4, the aluminum tanning agents prepared in Examples 1-4 also cause less color pollution to the leather embryo and can be applied to white leather or light-colored leather.

[0092] Although some specific embodiments of the present invention have been described in detail by way of examples, those skilled in the art should understand that the above examples are only for illustration and not for limiting the scope of the present invention. Those skilled in the art should understand that the above embodiments can be modified without departing from the scope and spirit of the present invention. The scope of the present invention is defined by the appended claims.

Claims

1. A strong color fixing and environmentally friendly synthetic aluminum tanning agent, characterized in that: The raw materials include, by weight: 31-33 parts of formic acid, 20-23 parts of hydroxyacetic acid, 20 parts of sodium aluminate, and 30 parts of water.

2. A method for preparing a strong color-fixing and environmentally friendly synthetic aluminum tanning agent, characterized in that: The steps include: S1: Start stirring and add 30 parts of water into the reactor; S2: Turn on the cooling water, maintain the temperature below 55°C, slowly add 20 parts of sodium aluminate in steps, and after the addition, maintain the temperature at 50-55°C and stir for 60 minutes; S3: Add 31-33 parts of formic acid and 20-23 parts of glycolic acid into another reaction kettle and start stirring; S4: Turn on the cooling water, maintain the temperature below 40°C, and drip the solution obtained in S2 into the reactor in S3 for 90-120 minutes; S5: After the solution in S2 is added dropwise, turn off the cooling, turn on the heating, maintain the temperature at 80-90°C, and react for 2-5 hours; after cooling, a colorless and transparent synthetic aluminum tanning agent with a pH of 3.0-4.0 and a solid content of 50.0-55.0% can be obtained.

3. An application of the aluminum tanning agent according to claim 1, characterized in that: Used for leather fatliquoring and color fixing.

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