Process for the preparation of chromium-free tanning agents based on oxidized kappa carrageenan

Abstract

The application discloses a preparation method of a chrome-free tanning agent based on oxidized K-type carrageenan, and specifically comprises the following steps: mixing the oxidized K-type carrageenan and water, heating under stirring, adding ethylene glycol diglycidyl ether and water drop by drop through a constant-pressure burette after the mixture is fully dissolved, adding tetramethyl ethylenediamine after the dropwise adding is completed, stirring at constant temperature, precipitating and purifying the product with anhydrous ethanol after cooling, and freeze-drying to obtain the chrome-free tanning agent based on the oxidized K-type carrageenan. 2+ The oxidization of the hydrogen peroxide / Cu 2+ system is used to oxidize the K-type carrageenan, so that a large number of active aldehyde groups and carboxyl groups are introduced into the K-type carrageenan molecules; the grafting reaction of a large number of epoxy groups in the ethylene glycol diglycidyl ether and the hydroxyl groups of the oxidized K-type carrageenan molecules is used to develop the chrome-free tanning agent with good moisture and heat stability and antibacterial property, which is beneficial to the clean and sustainable development of tanning.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of leather tanning, and particularly relates to a preparation method of a chrome-free tanning agent based on oxidized k-type carrageenan. BACKGROUND

[0002] Leather tanning agents are chemical reagents capable of making leather soft, elastic, strong, water-resistant, heat-resistant, corrosion-resistant and chemically stable, and mainly include inorganic tanning agents and organic tanning agents. At present, the most widely used tanning agent is a chrome tanning agent, which has excellent tanning effect. However, the chrome waste liquid poses a serious threat to the environment and ecological balance. Therefore, the development of environmentally friendly and renewable chrome-free tanning agents has become a major research direction.

[0003] The commonly used chrome-free tanning agents include metal chrome-free tanning agents, plant tanning agents, aldehyde tanning agents and new synthetic tanning agents. The metal chrome-free tanning agents have different characteristics, and the metal reserves are abundant and relatively environmentally friendly. The commonly used single metal chrome-free tanning agent in leather making is zirconium tanning agent. The zirconium tanning agent generally exists in the form of a tetramer complex in the solution during tanning, and can be combined with collagen at a pH of 1.5-2.0, but the binding force is weak and the tanning can be easily washed off, resulting in tanning retreatment. The aldehyde tanning agent tanned leather is resistant to washing, but has a low shrinkage temperature, and the finished leather is prone to yellowing and is harmful to the environment and human beings. The new synthetic tanning agent, such as an aromatic synthetic tanning agent, is prepared by condensation of sulfonated or sulfited phenol and formaldehyde, and has excellent tanning properties. The plant tanning agent has many varieties and is easy to produce, and the finished leather is solid, full, breathable and sweat-absorbing, and the waste can be degraded and is environmentally friendly. K-type carrageenan is a functional natural high molecular polysaccharide extracted from the papillate kappa-carrageenan in the seaweed kappa-carrageenan, and has a sulfated content of 25%-30%, and a sulfated group on the 1,3-linked D-galactose unit. The aqueous solution of k-type carrageenan has thermal reversibility, and is sensitive to inorganic salts and pH, and has good rheological properties, such as thickening property, stability and emulsifying property. SUMMARY

[0004] The purpose of the present application is to provide a preparation method of a chrome-free tanning agent based on oxidized k-type carrageenan, which has good moisture and heat resistance and antibacterial properties.

[0005] The technical scheme adopted by the present application is a preparation method of a chrome-free tanning agent based on oxidized k-type carrageenan, which is implemented according to the following steps:

[0006] Step 1, preparing oxidized k-type carrageenan;

[0007] Step 2, mix the oxidized k-type carrageenan and water, and heat to 70-80 DEG C under stirring, after fully dissolved, add ethylene glycol diglycidyl ether and water by constant pressure burette, after dropwise addition, add tetramethyl ethylenediamine, constant temperature stirring, after cooling, precipitate with anhydrous ethanol and purify the product, freeze-drying, to obtain the chromium-free tanning agent based on oxidized k-type carrageenan.

[0008] The application also has the characteristics that,

[0009] In step 1, specifically,

[0010] Mix the k-type carrageenan and water, heat to 70-80 DEG C and stir for 30-60 min, after fully dissolved, to obtain the k-type carrageenan solution; reduce the system temperature to 40-45 DEG C and add hydrogen peroxide solution and copper sulfate solution to the k-type carrageenan solution, react for 12-24 h under light shielding condition, then heat the mixture in water bath, wash the obtained solution with anhydrous ethanol for 2-3 times, and vacuum dry to obtain the oxidized k-type carrageenan.

[0011] The mass ratio of k-type carrageenan to water is 1:10-15; the volume ratio of k-type carrageenan solution, hydrogen peroxide solution and copper sulfate solution is 250-350:5-20:2-5.

[0012] The mass percentage of hydrogen peroxide solution is 20-30wt%; the mass percentage of copper sulfate solution is 0.05-0.1wt%.

[0013] The heating temperature is 90-100 DEG C, and the heating time is 5-10 min; the drying temperature is 45-50 DEG C, and the drying time is 48-60 h.

[0014] In step 2, the heating and stirring time is 20-30 min, the dropwise addition time is 30-40 min, and the constant temperature stirring time is 3-4 h.

[0015] In step 2, the mass ratio of oxidized k-type carrageenan to water is 1:5-10; the amount-of-substance ratio of oxidized k-type carrageenan to ethylene glycol diglycidyl ether is 1:2.1-4.1; the mass ratio of ethylene glycol diglycidyl ether to water is 1:1-2; and the mass ratio of tetramethyl ethylenediamine to oxidized k-type carrageenan is 1:100-200.

[0016] The application has the advantages that: the application takes the natural high molecular polysaccharide material k-type carrageenan with good stability, green environmental protection and renewable as the main raw material; through hydrogen peroxide / Cu 2+The oxidation of the system oxidizes the k-type carrageenan, so that a large number of active aldehyde groups and carboxyl groups are introduced on the k-type carrageenan molecules; a large number of epoxy groups in ethylene glycol diglycidyl ether are used to carry out grafting reaction with the hydroxyl groups of the k-type carrageenan molecules after oxidation, so that a chrome-free tanning agent with good wet heat stability and antibacterial property is developed, which is conducive to the clean and sustainable development of leather making. DETAILED DESCRIPTION

[0017] The application will be described in detail below in combination with specific embodiments.

[0018] The application is based on a preparation method of the chrome-free tanning agent based on oxidized k-type carrageenan, and is specifically implemented according to the following steps:

[0019] Step 1, mix the k-type carrageenan with water, heat to 70-80℃ and stir for 30-60 min, and after complete dissolution, obtain a k-type carrageenan solution; reduce the temperature of the system to 40-45℃ and add hydrogen peroxide solution and copper sulfate solution to the k-type carrageenan solution, react for 12-24 h under light shielding conditions, then heat the obtained mixture in a water bath, the heating temperature is 90-100℃, and the heating time is 5-10 min, wash the obtained solution with anhydrous ethanol for 2-3 times, and vacuum dry to obtain oxidized k-type carrageenan;

[0020] The mass ratio of k-type carrageenan to water is 1:10-15;

[0021] The drying temperature is 45-50℃, and the drying time is 48-60 h;

[0022] The mass percentage of the hydrogen peroxide solution is 20-30wt%; the mass percentage of the copper sulfate solution is 0.05-0.1wt%;

[0023] The volume ratio of the k-type carrageenan solution, the hydrogen peroxide solution and the copper sulfate solution is 250-350:5-20:2-5;

[0024] Step 2, mix the oxidized k-type carrageenan with water, heat to 70-80℃ under stirring, and stir for 20-30 min, then add ethylene glycol diglycidyl ether and water dropwise using a constant pressure burette, the dropwise adding time is 30-40 min, after the dropwise adding is completed, add tetramethyl ethylenediamine, and constant temperature stir for 3-4 h, then precipitate and purify the product using anhydrous ethanol after cooling, and freeze dry to obtain the chrome-free tanning agent based on oxidized k-type carrageenan.

[0025] The mass ratio of the oxidized k-type carrageenan to water is 1:5-10; the amount-of-substance ratio of the oxidized k-type carrageenan to ethylene glycol diglycidyl ether is 1:2.1-4.1; the mass ratio of ethylene glycol diglycidyl ether to water is 1:1-2; the mass ratio of tetramethyl ethylenediamine to the oxidized k-type carrageenan is 1:100-200;

[0026] In the method, the k-type carrageenan with good stability, green environmental protection and renewable natural polymer polysaccharide material is used as a main raw material; the k-type carrageenan is oxidized through the oxidation of the hydrogen peroxide / Cu 2+ The oxidation of the system is used for oxidizing the k-type carrageenan, so that a large number of active aldehyde groups and carboxyl groups are introduced on the k-type carrageenan molecules; the grafting reaction is carried out between the large number of epoxy groups of the ethylene glycol diglycidyl ether and the hydroxyl groups of the k-type carrageenan molecules after oxidation, so that the chrome-free tanning agent of the oxidized k-type carrageenan with high stability, without chromium and with antibacterial effect is developed; the chrome-free tanning agent has the following advantages:

[0027] 1) In the method, the natural polymer polysaccharide is used as the raw material for preparing the chrome-free tanning agent, which is green, environmentally friendly and non-toxic, and meets the requirements of the cleaning and sustainable development of the leather industry;

[0028] 2) A large number of aldehyde groups and carboxyl groups are introduced into the molecular structure of the chrome-free tanning agent, so that the chrome-free tanning agent has higher reactivity, can be reacted with the amino groups on the collagen through Schiff base reaction and amidation reaction respectively, is beneficial to the combination of the tanning agent with the leather and improves the absorption efficiency of the tanning agent.

[0029] Example 1

[0030] The preparation method of the chrome-free tanning agent based on the oxidized k-type carrageenan comprises the following steps:

[0031] A proper amount of water is placed in a 500ml three-necked flask, 25g of k-type carrageenan is slowly added, the temperature is increased to 70℃ and the k-type carrageenan is continuously stirred until the k-type carrageenan is completely dissolved; the temperature is reduced to 40℃, 5ml of hydrogen peroxide solution and 2ml of copper sulfate solution are added into the k-type carrageenan solution, the reaction is carried out for 12h under light-proof conditions, then the obtained mixture is heated to 90℃ and kept in a water bath for 5min, then the obtained solution is washed with anhydrous ethanol for 2 times and is placed in a 45℃ vacuum oven for 48h, so that the oxidized k-type carrageenan is obtained; 2g of the k-type carrageenan after oxidation and water are placed in a 250ml three-necked flask, the temperature is gradually increased to 70℃ under continuous stirring, after the k-type carrageenan after oxidation is completely dissolved, 5g of ethylene glycol diglycidyl ether and water are added through a constant pressure burette, the titration time is 30min, 1% of tetramethyl ethylenediamine is added, constant temperature stirring is carried out for 3h, after cooling, the product is precipitated and purified with anhydrous ethanol, and then is subjected to freeze drying, so that the chrome-free tanning agent based on the oxidized k-type carrageenan is obtained.

[0032] k-type carrageenan and water in a mass ratio of 1:10; hydrogen peroxide solution in a mass percentage of 30wt%; copper sulfate solution in a mass percentage of 0.05wt%; oxidized k-type carrageenan and water in a mass ratio of 1:5; oxidized k-type carrageenan and ethylene glycol diglycidyl ether in a molar ratio of 1:2.1; ethylene glycol diglycidyl ether and water in a mass ratio of 1:1; tetramethyl ethylenediamine and oxidized k-type carrageenan in a mass ratio of 1:100;

[0033] The oxidation value of the prepared oxidized k-type carrageenan in this example is 40%.

[0034] Example 2

[0035] The preparation method of the chromium-free tanning agent based on oxidized k-type carrageenan comprises the following steps:

[0036] A proper amount of water was placed in a 500ml three-necked flask, 35g of k-type carrageenan was slowly added, the temperature was raised to 80℃ and continuously stirred until the k-type carrageenan was completely dissolved; the temperature was lowered to 45℃ and 20ml of hydrogen peroxide solution and 5ml of copper sulfate solution were added to the above k-type carrageenan solution, and the reaction was carried out under light-proof conditions for 24h, then the obtained mixture was heated to 100℃ and kept in a water bath for 10min, then the obtained solution was washed with anhydrous ethanol for 3 times and then placed in a 50℃ vacuum oven for 60h, thus the oxidized k-type carrageenan was obtained; the oxidation value of the prepared oxidized k-type carrageenan is 71%.

[0037] 5g of oxidized k-type carrageenan and water were placed in a 250ml three-necked flask, the temperature was gradually raised to 80℃ under continuous stirring, after the oxidized k-type carrageenan was completely dissolved, 10g of ethylene glycol diglycidyl ether and water were added dropwise by using a constant pressure burette, the titration time was 40min, 1% of tetramethyl ethylenediamine was added, constant temperature stirring was carried out for 4h, after cooling, the product was precipitated and purified with anhydrous ethanol, and then freeze-drying was carried out, thus the chromium-free tanning agent based on oxidized k-type carrageenan was obtained.

[0038] k-type carrageenan and water in a mass ratio of 1:15; hydrogen peroxide solution in a mass percentage of 30wt%; copper sulfate solution in a mass percentage of 0.05wt%; oxidized k-type carrageenan and water in a mass ratio of 1:10; stirring time for the complete dissolution of oxidized k-type carrageenan is 30min; stirring speed is 300r / min; oxidized k-type carrageenan and ethylene glycol diglycidyl ether in a molar ratio of 1:4.1; ethylene glycol diglycidyl ether and water in a mass ratio of 1:2; tetramethyl ethylenediamine and oxidized k-type carrageenan in a mass ratio of 1:200;

[0039] Example 3

[0040] The preparation method of the chromium-free tanning agent based on oxidized k-type carrageenan comprises the following steps:

[0041] An appropriate amount of water was placed in a 500ml three-necked flask, 30g of k-type carrageenan was slowly added, the temperature was raised to 75℃ and continuously stirred until the k-type carrageenan was completely dissolved; preparation of oxidized k-type carrageenan: the temperature was reduced to 40℃ and 15ml of hydrogen peroxide solution and 4ml of copper sulfate solution were added to the above k-type carrageenan solution, reacted for 12h under light-proof conditions, then the obtained mixture was heated to 95℃ and kept in a water bath for 8min, then the obtained solution was washed with anhydrous ethanol for 2 times and then placed in a 45℃ vacuum oven for 50h to obtain the oxidized k-type carrageenan; the oxidation value of the prepared oxidized k-type carrageenan was 60%.

[0042] An appropriate amount of water was placed in a 500ml three-necked flask, 30g of k-type carrageenan was slowly added, the temperature was raised to 75℃ and continuously stirred until the k-type carrageenan was completely dissolved; preparation of oxidized k-type carrageenan: the temperature was reduced to 40℃ and 15ml of hydrogen peroxide solution and 4ml of copper sulfate solution were added to the above k-type carrageenan solution, reacted for 12h under light-proof conditions, then the obtained mixture was heated to 95℃ and kept in a water bath for 8min, then the obtained solution was washed with anhydrous ethanol for 2 times and then placed in a 45℃ vacuum oven for 50h to obtain the oxidized k-type carrageenan; the oxidation value of the prepared oxidized k-type carrageenan was 60%.

[0043] The mass ratio of k-type carrageenan to water was 1:13; the mass percentage of hydrogen peroxide solution was 30wt%; the mass percentage of copper sulfate solution was 0.05wt%; the mass ratio of oxidized k-type carrageenan to water was 1:5; the stirring time for the complete dissolution of oxidized k-type carrageenan was 25min; the stirring speed was 350r / min; the amount-of-substance ratio of oxidized k-type carrageenan to ethylene glycol diglycidyl ether was 1:3.1; the mass ratio of ethylene glycol diglycidyl ether to water was 1:1; the mass ratio of tetramethyl ethylenediamine to oxidized k-type carrageenan was 1:100;

[0044] Example 4

[0045] The preparation method of the chromium-free tanning agent based on oxidized k-type carrageenan provided by the present application is as follows:

[0046] An appropriate amount of water was placed in a 500ml three-necked flask, 30g of k-type carrageenan was slowly added, the temperature was raised to 75℃ and continuously stirred until the k-type carrageenan was completely dissolved; preparation of oxidized k-type carrageenan: the temperature was reduced to 40℃ and 15ml of hydrogen peroxide solution and 4ml of copper sulfate solution were added to the above k-type carrageenan solution, reacted for 12h under light-proof conditions, then the obtained mixture was heated to 95℃ and kept in a water bath for 8min, then the obtained solution was washed with anhydrous ethanol for 2 times and then placed in a 45℃ vacuum oven for 50h to obtain the oxidized k-type carrageenan; the oxidation value of the prepared oxidized k-type carrageenan was 60%.

[0047] 5 g of oxidized k-carrageenan and water were placed in a 250 ml three-necked flask, and gradually heated to 70 °C under constant stirring. After the oxidized k-carrageenan was fully dissolved, 5 g of ethylene glycol diglycidyl ether and water were added dropwise using a constant pressure burette, with a titration time of 30 min. 1% tetramethyl ethylenediamine was added, and constant temperature stirring was carried out for 4 h. After cooling, the product was precipitated with anhydrous ethanol and purified, and then freeze-dried to obtain a powder, which was the chromium-free tanning agent based on oxidized k-carrageenan.

[0048] The mass ratio of k-carrageenan to water was 1:10; the mass percentage of hydrogen peroxide solution was 30 wt%; the mass percentage of copper sulfate solution was 0.1 wt%;

[0049] The mass ratio of oxidized k-carrageenan to water was 1:5; the stirring time for the oxidized k-carrageenan to be fully dissolved was 30 min; the stirring speed was 300 r / min; the molar ratio of oxidized k-carrageenan to ethylene glycol diglycidyl ether was 1:3.1; the mass ratio of ethylene glycol diglycidyl ether to water was 1:1; the mass ratio of tetramethyl ethylenediamine to oxidized k-carrageenan was 1:100;

[0050] The chromium-free tanning agent based on oxidized k-carrageenan prepared in Example 2 was used in the tanning process of sheep acid skin. Table 1 shows the specific operation process of the chromium-free tanning agent based on oxidized k-carrageenan applied to the tanning experiment of sheep acid skin:

[0051] Table 1 Tanning process of sheep acid skin using chromium-free tanning agent based on oxidized k-carrageenan

[0052]

[0053] After the chromium-free tanning agent based on oxidized k-carrageenan prepared in Example 2 was tanned by the tanning process in Table 1, the shrinkage temperature, elongation at break, and tensile strength of the crust were tested, and the chromium-free tanning agent based on oxidized k-carrageenan was characterized by infrared and nuclear magnetic resonance, which proved the tanning effect of the chromium-free tanning agent.

Claims

1. A process for the preparation of chromium-free tanning agents based on oxidized kappa carrageenan, characterized in that, Specifically, the following steps are implemented: Step 1, preparation of oxidized k-type carrageenan; specifically: Mix k-type carrageenan with water, heat to 70-80°C and stir for 30-60 min, after complete dissolution, k-type carrageenan solution is obtained; the temperature of the system is reduced to 40-45°C and hydrogen peroxide solution and copper sulfate solution are added to the above k-type carrageenan solution, and the reaction is carried out under light-free conditions for 12-24 h, then the obtained mixture is heated in water bath, the obtained solution is washed with anhydrous ethanol for 2-3 times, and vacuum dried to obtain oxidized k-type carrageenan; Step 2, mix the oxidized k-type carrageenan with water, heat to 70-80°C under stirring, after complete dissolution, add ethylene glycol diglycidyl ether and water with constant pressure burette, after the addition is completed, add tetramethyl ethylenediamine, constant temperature stirring, after cooling, precipitate with anhydrous ethanol and purify the product, freeze-drying to obtain chromium-free tanning agent based on oxidized k-type carrageenan; The heating and stirring time is 20-30 min, the dropping time is 30-40 min, and the constant temperature stirring time is 3-4 h; The mass ratio of oxidized k-type carrageenan to water is 1:5-10; the molar ratio of oxidized k-type carrageenan to ethylene glycol diglycidyl ether is 1:2.1-4.1; the mass ratio of ethylene glycol diglycidyl ether to water is 1:1-2; the mass ratio of tetramethyl ethylenediamine to oxidized k-type carrageenan is 1:100-200.

2. The process for the preparation of chromium-free tanning agent based on oxidized kappa carrageenan according to claim 1, characterized in that, The mass ratio of k-type carrageenan to water is 1:10-15; the volume ratio of k-type carrageenan solution, hydrogen peroxide solution and copper sulfate solution is 250-350:5-20:2-5.

3. The process for the preparation of chromium-free tanning agent based on oxidized kappa carrageenan according to claim 1, characterized in that, The mass percentage of hydrogen peroxide solution is 20-30wt%; the mass percentage of copper sulfate solution is 0.05-0.1wt%.

4. The process for the preparation of chromium-free tanning agent based on oxidized kappa carrageenan according to claim 1, characterized in that, The heating temperature is 90-100°C, and the heating time is 5-10 min; the drying temperature is 45-50°C, and the drying time is 48-60 h.

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