Efficient acrylic acid retanning agent and preparation method thereof

Abstract

The invention provides an efficient acrylic acid retanning agent and a preparation method thereof.The preparation method comprises the following steps that S1, deionized water is added into a reactor, the temperature is increased, acrylic acid I, an oxidizing agent I, a reducing agent I and ferrous sulfate are added, stage I reaction is conducted, and an intermediate I is obtained; s2, adding a chain transfer agent I, acrylic acid II, an oxidizing agent II and a reducing agent II into the intermediate I, and carrying out stage II reaction to obtain an intermediate II; s3, adding a chain transfer agent II, acrylic acid III, an oxidizing agent III and a reducing agent III into the intermediate II, and carrying out stage III reaction to obtain an intermediate III; and S4, adjusting the pH value of the reaction system containing the intermediate III to 5.0-7.0, and adding EDTA-2Na to obtain the acrylic acid retanning agent. According to the acrylic acid retanning agent prepared through the method, the molecular weight distribution of the product is extremely wide, the product contains large, medium and small molecular polymers at the same time, one acrylic acid retanning agent can replace multiple acrylic acid retanning agents for use, and retanned leather is good in hand feeling, uniform, round and good in rebound resilience.

Description

Technical Field

[0001] The invention relates to the technical field of retanning agents, in particular to a high-efficiency acrylic acid retanning agent and a preparation method thereof. Background Art

[0002] Acrylic acid retanning agent is a very important type of synthetic tanning agent in the leather making process. It contains more carboxyl groups in the molecular side chain, which can chemically combine with the amino group of skin collagen and the chromium salt bound in chrome-tanned leather. It is widely used in the retanning of pig, cattle, sheep and other leathers. Its main characteristics are: strong ability to combine with leather, good selective filling, can narrow the difference between parts and overcome the loose surface; it has a significant effect on thickening leather, can improve the flexibility and fullness of leather, and improve the physical and mechanical properties of finished leather; it has strong complexing ability with chromium, can promote chromium absorption, reduce the content of free chromium and unstable chromium in leather, and reduce the chromium content in waste liquid; the finished leather has good napping properties; acrylic acid retanning agent is light-resistant and aging-resistant, and can lighten the color of chrome-tanned leather, so it is particularly suitable for the retanning of white and light-colored leather.

[0003] Acrylic acid retanning agents are a type of polymer with a certain relative molecular mass and relative molecular mass distribution, usually divided into large molecular, medium molecular and small molecular acrylic acid retanning agents. Large molecular retanning agents have strong filling ability, plump leather and small position difference, but poor permeability and easy to scratch; medium molecular retanning agents have a wide range of applications and insufficient filling; small molecular retanning agents have finer and smoother leather grain, but poor filling ability. In the leather making process, a variety of acrylic acid retanning agents are often used in combination to meet the requirements of leather feel, but there are problems such as lower environmental protection, more complicated worker operation and higher cost. Summary of the invention

[0004] The present invention is used to provide a method for preparing an acrylic acid retanning agent, so as to achieve the purpose of improving the comprehensive performance of the acrylic acid retanning agent. The acrylic acid retanning agent provided by the present invention is an environmentally friendly product, and has the advantages of outstanding functionality and high cost performance.

[0005] Based on this, the present invention provides a method for preparing a high-efficiency acrylic acid retanning agent. The preparation method provided by the present invention can prepare a high-efficiency acrylic acid retanning agent with a very wide molecular weight distribution, and at the same time contain large, medium and small molecular weight distributions, which can reduce the total amount and type of acrylic acid retanning agents, and use one acrylic acid retanning agent to replace two or more acrylic acid retanning agents. After the acrylic acid retanning agent obtained by the present invention is used for retanning, the finished leather is plump, uniform, and has good toughness and elasticity, and is very cost-effective.

[0006] Based on this, the above specific plan is:

[0007] First, the present invention provides a method for preparing a high-efficiency acrylic acid retanning agent, comprising the following steps:

[0008] S1: Add a set amount of deionized water into the reactor, increase the temperature, add acrylic acid I, oxidant I, reducing agent I, and ferrous sulfate, and carry out stage I reaction to obtain intermediate I;

[0009] S2 adds chain transfer agent I, acrylic acid II, oxidant II, and reducing agent II to intermediate I to carry out stage II reaction to obtain intermediate II;

[0010] S3: adding chain transfer agent II, acrylic acid III, oxidant III, and reducing agent III to intermediate II to carry out stage III reaction to obtain intermediate III;

[0011] S4 comprises a reaction system of intermediate III, adjusts the pH value of the reaction system, and adds EDTA-2Na to obtain an acrylic acid retanning agent.

[0012] According to some preferred embodiments, the raw material components of the acrylic acid retanning agent are, by weight, 100 parts of acrylic acid, 1-2 parts of oxidant, 1-2 parts of reducing agent, 0.8-2 parts of chain transfer agent, 50-60 parts of pH adjuster, 0.5-1.5 parts of EDTA-2Na, 0.005-0.01 parts of ferrous sulfate, and 300-320 parts of deionized water; the acrylic acid, the oxidant and the reducing agent are each independently divided into three parts, and the chain transfer agent is divided into two parts.

[0013] According to some preferred embodiments, the acrylic acid, the oxidizing agent and the reducing agent are each independently divided into three parts.

[0014] According to some preferred embodiments, the chain transfer agent is divided into two parts, chain transfer agent I:chain transfer agent II=1:3.

[0015] According to some preferred embodiments, the oxidant includes at least one of ammonium persulfate and sodium persulfate.

[0016] According to some preferred embodiments, the reducing agent includes at least one of sodium bisulfite and sodium pyrosulfite.

[0017] According to some preferred embodiments, the chain transfer agent includes at least one of phosphorous acid and formic acid.

[0018] According to some preferred embodiments, at least one of sodium hydroxide, potassium hydroxide and ammonia water is used for pH adjustment.

[0019] According to some preferred embodiments, the oxidant, the reducing agent, the ferrous sulfate, and the pH regulator are prepared into a solution for standby use. The specific dosages are as follows: the oxidant and the reducing agent are respectively added with 10-20 times of deionized water to prepare a solution for standby use; the ferrous sulfate is dissolved with 100 times of deionized water to prepare a solution for standby use; the alkaline pH regulator is added with 1.2 times of deionized water to prepare a solution for standby use.

[0020] According to some preferred embodiments, each process step is specifically defined as follows:

[0021] In S1, a set amount of deionized water is added to the reactor and the temperature is raised to 35-65°C;

[0022] In S1, the reaction temperature in stage I is 35-65°C, and after the reaction is completed, it is kept at 60-65°C for 20-40 minutes;

[0023] In S2, the reaction temperature in stage II is 35-65°C, and after the reaction is completed, it is kept at 60-65°C for 20-40 minutes;

[0024] In S3, the reaction temperature of stage III is 35-65°C. After the reaction is completed, it is kept at 80-90°C for 100-150 minutes. In S4, the temperature is lowered to ≤50°C, and the pH value is adjusted to 5.0-7.0.

[0025] Second, the present invention provides a high-efficiency acrylic acid retanning agent obtained by the above-mentioned preparation method.

[0026] The beneficial effects achieved by the present invention are:

[0027] (1) The acrylic acid retanning agent prepared by the present invention has a very wide molecular weight distribution, and the product contains large, medium and small molecules at the same time. One acrylic acid retanning agent can replace multiple acrylic acid retanning agents.

[0028] (2) The acrylic acid retanning agent prepared by the present invention provides leather with good hand feel, uniform roundness and good resilience after retanning.

[0029] (3) The use of the acrylic acid retanning agent prepared by the present invention can reduce the chromium content in wastewater. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 The figure is the gel chromatography result of Example 1 and Comparative Example 1. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical scheme and advantages of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention will be described clearly and completely below. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or conditions recommended by the manufacturer. If the manufacturer of the reagents or instruments used is not specified, they are all conventional products that can be purchased commercially.

[0032] Raw materials: industrial deionized water, industrial grade 85% formic acid, industrial grade ammonium persulfate, industrial grade sodium bisulfite, industrial grade sodium pyrosulfite, industrial grade ferrous sulfate, industrial grade phosphorous acid, industrial grade acrylic acid (general acid), industrial grade sodium hydroxide, industrial grade potassium hydroxide, industrial grade EDTA-2Na.

[0033] Example 1

[0034] This embodiment provides a method for preparing a high-efficiency acrylic acid retanning agent, comprising the following steps:

[0035] First, 1.5 g of ammonium persulfate is dissolved in 30 g of deionized water to prepare an ammonium persulfate solution, and the solution is evenly divided into three portions for later use; 1.5 g of sodium bisulfite is dissolved in 30 g of deionized water to prepare a sodium bisulfite solution, and the solution is evenly divided into three portions for later use; 0.1 g of ferrous sulfate is dissolved in 100 g of deionized water, and 10 g of the solution is taken for later use; 0.8 g of phosphorous acid is taken and divided into two portions of 0.2 g and 0.6 g; 100 g of acrylic acid is taken and evenly divided into three portions for later use; 55 g of sodium hydroxide is dissolved in 67.8 g of deionized water to prepare a sodium hydroxide solution.

[0036] 180 g of deionized water was added to a 500 ml three-necked flask, the temperature was raised to 35-38 ° C, the heating source was removed, the first portion of acrylic acid, ammonium persulfate solution, sodium bisulfite solution and 10 g of ferrous sulfate solution were added, the system began to heat up to about 65 ° C, and the temperature was kept at 65-68 ° C for 30 minutes after the heating was completed; the temperature was lowered to 35-38 ° C after the insulation was completed, the heating source was removed, 0.2 g of phosphorous acid, the second portion of acrylic acid, ammonium persulfate solution, sodium bisulfite solution were added, and the system began to heat up to The system is heated to about 65°C, and the temperature is kept at 65-68°C for 30 minutes after the heating is completed; the temperature is lowered to 35-38°C after the heating is completed, and the heating source is removed. 0.6g of phosphorous acid, the third portion of acrylic acid, ammonium persulfate solution, and sodium bisulfite solution are added. The system begins to heat to about 65°C, and the heating is completed. The system is then kept at 80-85°C for 120 minutes; after the heating is completed, the temperature is lowered to ≤50°C, and sodium hydroxide solution is added to adjust the pH value of the system to 5.0-7.0 and the solid content to 28%-32%, and then 1g of EDTA-2Na is added and stirred evenly to obtain a high-efficiency acrylic acid retanning agent.

[0037] Example 2

[0038] This embodiment provides a method for preparing a high-efficiency acrylic acid retanning agent, comprising the following steps:

[0039] First, 1.8 g of sodium persulfate is dissolved in 30 g of deionized water to prepare an ammonium persulfate solution, which is evenly divided into three portions for later use; 1.8 g of sodium pyrosulfite is dissolved in 30 g of deionized water to prepare a sodium pyrosulfite solution, which is evenly divided into three portions for later use; 0.1 g of ferrous sulfate is dissolved in 100 g of deionized water, and 10 g of the solution is taken for later use; 2 g of formic acid is taken, and the solution is divided into two portions of 0.5 g and 1.5 g; 100 g of acrylic acid is taken, and the solution is evenly divided into three portions for later use; 55 g of sodium hydroxide is dissolved in 67.8 g of deionized water to prepare a sodium hydroxide solution.

[0040] Add 180g of deionized water to a 500ml three-necked flask, heat it to 35-38°C, remove the heating source, add the first portion of acrylic acid, sodium persulfate solution, sodium metabisulfite solution and 10g of ferrous sulfate solution, and the system begins to heat to about 65°C, and heats to 65-68°C for 30 minutes after heating; cool to 35-38°C after heating, remove the heating source, add 0.5g of formic acid, the second portion of acrylic acid, sodium persulfate solution, sodium metabisulfite solution, and the system begins to heat to about 65°C, and heats to 65-68°C for 30 minutes after heating; cool to 35-38°C after heating, remove the heating source, add 0.5g of formic acid, the second portion of acrylic acid, sodium persulfate solution, and sodium metabisulfite solution, and the system begins to heat to about 65°C, and heats to 65- The method comprises the steps of: keeping the temperature at 68°C for 30 minutes; cooling the temperature to 35-38°C after the heat preservation is completed, removing the heating source, adding 1.5 g of formic acid, the third portion of acrylic acid, a sodium persulfate solution and a sodium pyrosulfite solution, and heating the system to about 65°C. After the heat preservation is completed, the system is kept at 80-85°C for 120 minutes; cooling the temperature to ≤50°C after the heat preservation is completed, adding a sodium hydroxide solution to adjust the pH value of the system to 5.0-7.0 and the solid content to 28%-32%, and then adding 0.5 g of EDTA-2Na and stirring evenly to obtain a high-efficiency acrylic acid retanning agent.

[0041] Comparative Example 1

[0042] This comparative example provides a method for preparing an acrylic acid retanning agent, comprising the following steps:

[0043] First, take 0.5g of ammonium persulfate and dissolve it in 10g of deionized water to prepare an ammonium persulfate solution; take 0.5g of sodium bisulfite and dissolve it in 10g of deionized water to prepare a sodium bisulfite solution; take 0.1g of ferrous sulfate and dissolve it in 100g of deionized water, and take 10g of the solution for later use; take 40g of acrylic acid for later use; take 22.2g of sodium hydroxide and dissolve it in 27.1g of deionized water to prepare a sodium hydroxide solution.

[0044] 180 g of deionized water was added to a 500 ml three-necked flask, the temperature was raised to 35-38° C., the heating source was removed, acrylic acid, ammonium persulfate solution, sodium bisulfite solution and 10 g of ferrous sulfate solution were added, the system temperature began to rise to about 70° C., and then the temperature was raised to 80-85° C. and kept warm for 120 minutes; after the heat preservation was completed, the temperature was lowered to ≤50° C., sodium hydroxide solution was added to adjust the pH of the system to 5.0-7.0, and then 1 g of EDTA-2Na was added and stirred evenly to prepare an acrylic acid retanning agent.

[0045] Test Example 1

[0046] (1) Gel permeation chromatography

[0047] Using Example 1 and Comparative Example 1 as samples, gel permeation chromatography was performed. The results are as follows: Figure 1 shown.

[0048] Depend on Figure 1 It can be seen that the product of Comparative Example 1 is a macromolecular polymer, and the product of Example 1 has macromolecular, medium-molecular and small-molecular polymers.

[0049] (2) Application test

[0050] The yellow cattle top layer blue wet leather (purchased from outside) was selected for comparative test using Examples 1-2, Comparative Example 1, Klein PR (macromolecule product), Apa TP340 (medium molecule product), BASF RV (small molecule product) and 1:1:1 mixed samples of PR, TP340 and RV, with an acrylic acid dosage of 10% (based on the weight of blue leather). The leather was treated by conventional processes such as chrome retanning, filling, oiling and solid acid, and then tested. The fullness, selective filling and grain tightness are based on the tester's perception; the thickening rate is based on the QB / T2709-2005 standard; the tensile strength is based on the QB / T2710-2005 standard; the shrinkage temperature is based on the QB / T2713-2005 standard; the chromium content in wastewater is based on the CZ 05-515 standard "Leather Analysis and Inspection" of Northwest University of Light Industry. The results of the application comparison experiment are shown in Table 1.

[0051] From the results in Table 1, it can be seen that after adding the acrylic acid retanning agent prepared by the method of the present invention, the finished leather is plump, firm, and has good toughness, the chromium content in the wastewater is lower, and the comprehensive performance is excellent.

[0052]

Claims

1. A method for preparing a high-efficiency acrylic acid retanning agent, characterized in that: The steps include: S1 adds deionized water to a reactor, raises the temperature, adds acrylic acid I, oxidant I, reducing agent I, and ferrous sulfate, and performs a stage I reaction to obtain an intermediate I; S2 adds chain transfer agent I, acrylic acid II, oxidant II, and reducing agent II to intermediate I to carry out stage II reaction to obtain intermediate II; S3: adding chain transfer agent II, acrylic acid III, oxidant III, and reducing agent III to intermediate II to carry out stage III reaction to obtain intermediate III; S4 comprises a reaction system of intermediate III, adjusts the pH value of the reaction system, and adds EDTA-2Na to obtain an acrylic acid retanning agent.

2. The method for preparing a high-efficiency acrylic acid retanning agent according to claim 1, characterized in that: The raw material components of the acrylic acid retanning agent are calculated by weight, including 100 parts of acrylic acid, 1-2 parts of an oxidant, 1-2 parts of a reducing agent, 0.8-2 parts of a chain transfer agent, 50-60 parts of a pH adjuster, 0.5-1.5 parts of EDTA-2Na, 0.005-0.01 parts of ferrous sulfate and 300-320 parts of deionized water; the acrylic acid, the oxidant and the reducing agent are each independently divided into three parts, and the chain transfer agent is divided into two parts.

3. The method for preparing a high-efficiency acrylic acid retanning agent according to claim 2, characterized in that: Acrylic acid, oxidizing agent and reducing agent were each independently divided into three equal parts.

4. The method for preparing a high-efficiency acrylic acid retanning agent according to claim 2, characterized in that: The chain transfer agent is divided into two parts, chain transfer agent I:chain transfer agent II=1:

3.

5. The method for preparing a high-efficiency acrylic acid retanning agent according to claim 1, characterized in that: The oxidant includes at least one of ammonium persulfate and sodium persulfate.

6. The method for preparing a high-efficiency acrylic acid retanning agent according to claim 1, characterized in that: The reducing agent includes at least one of sodium bisulfite and sodium pyrosulfite.

7. The method for preparing a high-efficiency acrylic acid retanning agent according to claim 1, characterized in that: The chain transfer agent includes at least one of phosphorous acid and formic acid.

8. The method for preparing a high-efficiency acrylic acid retanning agent according to claim 1, characterized in that: The pH value is adjusted by using at least one of sodium hydroxide, potassium hydroxide and ammonia water.

9. The method for preparing a high-efficiency acrylic acid retanning agent according to any one of claims 1 to 8, characterized in that: The preparation method comprises at least one of features (A) to (E): (A) In S1, the deionized water in the reactor is heated to 35-38° C. before starting the polymerization reaction; (B) In S1, the reaction temperature in stage I is 35-65°C, and after the reaction is completed, the temperature is kept at 60-65°C for 20-40 minutes; (C) In S2, the reaction temperature in stage II is 35-65°C, and after the reaction is completed, the temperature is kept at 60-65°C for 20-40 minutes; (D) In ​​S3, the reaction temperature of stage III is 35-65°C, and after the reaction is completed, it is kept at 80-90°C for 100-150 minutes; (E) In S4, the temperature is lowered to ≤50°C and the pH value is adjusted to 5.0-7.

0.

10. A high-efficiency acrylic acid retanning agent obtained by the preparation method according to any one of claims 1 to 9.

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