A lanolin / soybean polysaccharide-based aged leather softening agent and its preparation method and application

Abstract

The present invention belongs to the technical field of leather softening agents, and specifically relates to a lanolin / soybean polysaccharide-based softening agent for aged leather, its preparation method, and application. The softening agent of the present invention is formed by mixing glycerol, aminosilicone oil, lanolin, and a soybean polysaccharide aqueous solution. The preparation method of the softening agent comprises: mixing the soybean polysaccharide aqueous solution and glycerol to obtain a first mixture; adding aminosilicone oil to the first mixture and mixing to obtain a second mixture; adding melted lanolin to the second mixture and mixing to obtain the lanolin / soybean polysaccharide-based softening agent for aged leather. The present invention uses pure natural soybean polysaccharides, glycerol, aminosilicone oil, and lanolin to prepare the lanolin / soybean polysaccharide-based softening agent for aged leather, which not only achieves deep penetration into aged leather and effective filling of fiber gaps, but also significantly improves the softness, color, and heat resistance of aged leather.

Description

Technical Field

[0001] The invention belongs to the technical field of leather softening agents, and particularly relates to an aged leather softening agent based on lanolin / soybean polysaccharide, and a preparation method and application thereof. Background Art

[0002] Leather, a vital material throughout human history, is not only widely used in daily life but also serves as a vital carrier of culture, history, and art. Leather artifacts, particularly ancient leather products, are a vital part of cultural heritage due to their unique artistic and historical value. However, over time, these precious leather artifacts, due to the natural environment, human factors, and improper conservation, experience varying degrees of aging, such as loss of luster, decreased softness, hardening, and embrittlement. These changes not only impact the aesthetics of these leather artifacts but also pose significant challenges to their preservation and display.

[0003] Traditional leather softening methods rely primarily on oils and chemicals. While these methods can restore leather's softness, long-term use of these chemicals can cause secondary damage to the leather and even have adverse effects on the environment and human health. In recent years, with the continuous advancement of science and technology, researchers have modified lecithin, lanolin, and castor oil to create a variety of compound fatliquors. While these compound fatliquors can improve leather's softness, the resulting modified compounds are irreversible and can cause secondary damage to crusted leather artifacts, limiting the potential for further conservation and research on these leather artifacts. Summary of the Invention

[0004] In response to the problems existing in the prior art, the present invention provides a lanolin / soybean polysaccharide-based aged leather softening agent, a preparation method and application thereof. The present invention adopts pure natural soybean polysaccharide, glycerin, amino silicone oil and lanolin to prepare the lanolin / soybean polysaccharide-based aged leather softening agent, which not only achieves deep penetration into aged leather and effective filling of fiber gaps, but also can significantly improve the softness, color and heat resistance of aged leather, providing scientific theoretical guidance for the softening, long-term preservation and display of aged leather cultural relics.

[0005] To achieve the above object, the present invention adopts the following technical solutions:

[0006] The first object of the present invention is to provide an aged leather softening agent based on lanolin / soybean polysaccharide, wherein the softening agent is prepared by mixing glycerin, amino silicone oil, lanolin and soybean polysaccharide aqueous solution, and the mass ratio of glycerin, amino silicone oil, lanolin and soybean polysaccharide aqueous solution is 2:1:1:10-25;

[0007] Among them, the mass percentage of the soybean polysaccharide aqueous solution is 3wt% to 5wt%. When the mass percentage of the soybean polysaccharide aqueous solution is less than 3wt%, the emulsion stratifies; when the mass percentage of the soybean polysaccharide aqueous solution is greater than 5wt%, the emulsion particle size becomes larger, and when the mass percentage of the soybean polysaccharide aqueous solution is greater than 5wt%, the soybean polysaccharide is difficult to dissolve.

[0008] A second object of the present invention is to provide a method for preparing an aged leather softening agent based on lanolin / soybean polysaccharide, which is prepared according to the following steps:

[0009] S1, mixing the soybean polysaccharide aqueous solution and glycerol to obtain a first mixture;

[0010] S2. Adding amino silicone oil to the first mixture and mixing to obtain a second mixture;

[0011] S3. Adding the heated and melted lanolin to the second mixture and mixing them to obtain an aged leather softening agent based on lanolin / soybean polysaccharide.

[0012] Preferably, in step S1, the mixing temperature is 50° C. to 60° C., the mixing time is 15 min to 30 min, and the rotation speed is 1500 r / min.

[0013] Preferably, in step S2, the mixing temperature is 50°C to 60°C, the mixing time is 15 min to 30 min, and the rotation speed is 1500 r / min.

[0014] Preferably, in step S3, the mixing temperature is 50°C to 60°C, the mixing time is 150 min to 180 min, and the rotation speed is 1500 r / min.

[0015] A third object of the present invention is to provide the application of the above-mentioned lanolin / soybean polysaccharide-based aged leather softening agent in the softening of aged leather, which is carried out according to the following steps:

[0016] Apply the aged leather softening agent based on lanolin / soy polysaccharide to the aged leather surface and let it dry.

[0017] Preferably, the aged leather softening agent based on lanolin / soybean polysaccharide is repeatedly applied to the aged leather surface, and is applied again after the aged leather has completely absorbed the softening agent, until the quality of the aged leather does not change, with an interval of 20 minutes between each application.

[0018] Preferably, before applying the aged leather softening agent based on lanolin / soy polysaccharide, the aged leather is first moistened with distilled water. Water molecules can penetrate into the fiber structure of the aged leather, making the aged leather fibers more swollen and soft, thereby facilitating the subsequent penetration and uniform distribution of the aged leather softening agent based on lanolin / soy polysaccharide.

[0019] Compared with the prior art, the present invention has the following beneficial effects:

[0020] 1. The present invention provides a lanolin / soy polysaccharide-based softening agent for aged leather. The lanolin / soy polysaccharide-based softening agent for aged leather is prepared using pure natural soybean polysaccharide, glycerin, amino silicone oil, and lanolin. The lanolin / soy polysaccharide-based softening agent for aged leather not only avoids the negative effects of chemical modification but also utilizes the natural properties of soybean polysaccharide, glycerin, amino silicone oil, and lanolin to achieve deep penetration into aged leather and effectively fill fiber gaps, significantly improving the softness, color, and heat resistance of aged leather.

[0021] Among them, glycerol and soybean polysaccharides both contain hydroxyl groups, and there are a large number of polar groups such as -OH and -COOH on the collagen molecules in aged leather. When glycerol and soybean polysaccharides are filled into the aged leather fiber network, they form hydrogen bonds with the collagen molecules, thereby significantly enhancing its heat resistance and providing an ideal environmentally friendly solution for the care of aged leather.

[0022] 2. The present invention provides a method for preparing an aged leather softening agent based on lanolin / soybean polysaccharide. A soybean polysaccharide aqueous solution and glycerol are mixed to obtain a first mixture, and then amino silicone oil is added to the first mixture to obtain a second mixture. Finally, melted lanolin is added to the second mixture and mixed to obtain an aged leather softening agent based on lanolin / soybean polysaccharide.

[0023] Among them, soybean polysaccharide has emulsifying and filling effects, glycerol serves as a humectant, amino silicone oil serves as a softener, and lanolin serves as a fatliquor. In the present invention, a soybean polysaccharide aqueous solution, glycerol, amino silicone oil, and lanolin are mixed to form an oil-in-water emulsion. The emulsifying and filling effects of soybean polysaccharide cooperate with the moisturizing property of glycerol to ensure the uniform dispersion and stability of each component during the mixing process, while improving the moisturizing property of the aged leather softening agent based on lanolin / soy polysaccharide. As a softener, amino silicone oil has the characteristics of permeability and reducing friction resistance between fibers, which cooperate with the moisturizing and moisturizing properties of lanolin, which not only enhances the softness and smoothness of the aged leather softening agent based on lanolin / soy polysaccharide on aged leather fibers, but also improves the overall softness and color of the aged leather.

[0024] 3. The present invention also provides the use of a lanolin / soy polysaccharide-based aged leather softening agent for softening aged leather. This lanolin / soy polysaccharide-based aged leather softening agent can effectively alleviate the hardening of aged leather, significantly improving its softness and elasticity, and achieving efficient softening while maintaining the appearance and quality of aged leather. Furthermore, it can enhance the thermal stability of aged leather and further promote the recovery of its elasticity, providing an efficient and practical solution for the repair and maintenance of aged leather. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is a particle size distribution diagram of the soybean polysaccharide aqueous solution used in Examples 4 to 6 of the present invention;

[0026] Figure 2 This is the infrared spectra of soybean polysaccharides used in Examples 1 to 6 and Comparative Examples 1 to 3 of the present invention;

[0027] Figure 3The present invention provides optical microscope photos and particle size distribution diagrams of the aged leather softening agent based on lanolin / soy polysaccharide of Examples 1 to 6 and Comparative Examples 2 to 3, wherein (a) is an optical microscope photo of the aged leather softening agent based on lanolin / soy polysaccharide of Example 1, (a1) is a particle size distribution diagram of the aged leather softening agent based on lanolin / soy polysaccharide of Example 1, and (a2) is an emulsion diagram of the aged leather softening agent based on lanolin / soy polysaccharide of Example 1; (b) is an optical microscope photo of the aged leather softening agent based on lanolin / soy polysaccharide of Example 2, and (b1) is an emulsion diagram of the aged leather softening agent based on lanolin / soy polysaccharide of Example 2. Particle size distribution diagram of the softening agent, (b2) is an emulsion diagram of the aged leather softening agent based on lanolin / soy polysaccharide in Example 2; (c) is an optical microscope photo of the aged leather softening agent based on lanolin / soy polysaccharide in Example 3, (c1) is a particle size distribution diagram of the aged leather softening agent based on lanolin / soy polysaccharide in Example 3, (c2) is an emulsion diagram of the aged leather softening agent based on lanolin / soy polysaccharide in Example 3; (d) is an optical microscope photo of the aged leather softening agent based on lanolin / soy polysaccharide in Example 4, (d1) is a particle size distribution diagram of the aged leather softening agent based on lanolin / soy polysaccharide in Example 4, (d2) (e) is an optical microscope photograph of the aged leather softening agent based on lanolin / soy polysaccharide in Example 5, (e1) is a particle size distribution diagram of the aged leather softening agent based on lanolin / soy polysaccharide in Example 5, and (e2) is an emulsion photograph of the aged leather softening agent based on lanolin / soy polysaccharide in Example 5; (f) is an optical microscope photograph of the aged leather softening agent based on lanolin / soy polysaccharide in Example 6, (f1) is a particle size distribution diagram of the aged leather softening agent based on lanolin / soy polysaccharide in Example 6, and (f2) is an emulsion photograph of the aged leather softening agent based on lanolin / soy polysaccharide in Example 6. (g) is an optical microscope photo of the aged leather softening agent based on lanolin / soy polysaccharide in comparative example 2, (g1) is a particle size distribution diagram of the aged leather softening agent based on lanolin / soy polysaccharide in comparative example 2, and (g2) is an emulsion photo of the aged leather softening agent based on lanolin / soy polysaccharide in comparative example 2; (h) is an optical microscope photo of the aged leather softening agent based on lanolin / soy polysaccharide in comparative example 3, (h1) is a particle size distribution diagram of the aged leather softening agent based on lanolin / soy polysaccharide in comparative example 3, and (h2) is an emulsion photo of the aged leather softening agent based on lanolin / soy polysaccharide in comparative example 3.

[0028] Figure 4These are comparative graphs of the softness of aged rubber-tanned leather samples before and after softening using the lanolin / soy polysaccharide-based aged leather softening agents of Examples 1 to 6 of the present invention, wherein (a) is a comparative graph of the softness of aged rubber-tanned leather samples before and after softening using the lanolin / soy polysaccharide-based aged leather softening agents of Examples 1, 2, and 3, and (b) is a comparative graph of the softness of aged rubber-tanned leather samples before and after softening using the lanolin / soy polysaccharide-based aged leather softening agents of Examples 4, 5, and 6;

[0029] Figure 5 These are digital photographs of aged rubber-tanned leather samples before and after softening using the lanolin / soybean polysaccharide-based aged leather softening agents of Examples 1 to 6 of the present invention;

[0030] Figure 6 Color difference analysis charts of aged leather softening agents based on lanolin / soy polysaccharides prepared in Examples 1 to 6 of the present invention before and after softening of aged rubber-tanned leather samples, wherein (a) is a color difference analysis chart of aged rubber-tanned leather samples before and after softening using the lanolin / soy polysaccharide-based aged leather softening agents of Examples 1, 2, and 3, and (b) is a color difference analysis chart of aged rubber-tanned leather samples before and after softening using the lanolin / soy polysaccharide-based aged leather softening agents of Examples 4, 5, and 6;

[0031] Figure 7 Thermogravimetric (TG) and differential thermogravimetric (DTG) curves of the aged leather softening agent based on lanolin / soy polysaccharide prepared in Examples 1 to 6 of the present invention before and after softening of aged rubber-tanned leather samples, wherein (a) is a TG / DTG curve of the aged leather softening agent based on lanolin / soy polysaccharide before and after softening of the aged rubber-tanned leather sample in Example 1, (b) is a TG / DTG curve of the aged leather softening agent based on lanolin / soy polysaccharide before and after softening of the aged rubber-tanned leather sample in Example 2, and (c) is a TG / DTG curve of the aged rubber-tanned leather sample in Example 1. Example 3 is a TG / DTG graph of the aged leather softening agent based on lanolin / soy polysaccharide before and after softening, (d) is a TG / DTG graph of the aged leather softening agent based on lanolin / soy polysaccharide before and after softening of the aged rubber-tanned leather sample application example 4, (e) is a TG / DTG graph of the aged leather softening agent based on lanolin / soy polysaccharide before and after softening of the aged rubber-tanned leather sample application example 5, (f) is a TG / DTG graph of the aged leather softening agent based on lanolin / soy polysaccharide before and after softening of the aged rubber-tanned leather sample application example 6;

[0032] Figure 8The present invention provides DSC curves of aged leather softening agents based on lanolin / soybean polysaccharides prepared in Examples 1 to 6 of the present invention before and after softening of aged rubber-tanned leather samples, wherein (a) is a DSC curve of the aged rubber-tanned leather sample before and after softening by the softening agent of Example 1, (b) is a DSC curve of the aged rubber-tanned leather sample before and after softening by the softening agent of Example 2, (c) is a DSC curve of the aged rubber-tanned leather sample before and after softening by the softening agent of Example 3, (d) is a DSC curve of the aged rubber-tanned leather sample before and after softening by the softening agent of Example 4, (e) is a DSC curve of the aged rubber-tanned leather sample before and after softening by the softening agent of Example 5, and (f) is a DSC curve of the aged rubber-tanned leather sample before and after softening by the softening agent of Example 6. DETAILED DESCRIPTION

[0033] The following is a clear and complete description of the technical solutions of the present invention, combined with the data in the embodiments of the present invention. Obviously, the embodiments described are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts are within the scope of protection of the present invention.

[0034] It should be noted that the professional terms used in the present invention are only for the purpose of describing specific embodiments and are not intended to limit the scope of protection of the present invention. Unless otherwise specified, the various raw materials, reagents, instruments and equipment used in the following embodiments of the present invention can be purchased from the market or prepared by existing methods.

[0035] In the existing technology, compound fatliquors are mainly prepared by chemically modifying lecithin, lanolin and castor oil. This modification process changes the original chemical structure of the natural ingredients, which will cause irreversible damage to leather cultural relics during use. At the same time, it limits the possibility of further protection and research of leather cultural relics, and also limits its application in the protection of crusted leather cultural relics.

[0036] To address these deficiencies, the present invention provides a lanolin / soy polysaccharide-based softening agent for aged leather. The softening agent is composed of a mixture of glycerol, aminosilicone oil, lanolin, and an aqueous soy polysaccharide solution, wherein the mass ratio of glycerol, aminosilicone oil, lanolin, and the aqueous soy polysaccharide solution is 2:1:1:10-25; the mass percentage of the aqueous soy polysaccharide solution is 3wt%-5wt%. The present invention prepares a softening agent for aged leather by mixing an emulsifying aqueous soy polysaccharide solution with glycerol, introducing aminosilicone oil as a softener, and combining it with the moisturizing and hydrating properties of lanolin. This method avoids the negative effects of chemical modification while utilizing the natural properties of soy polysaccharides, glycerol, aminosilicone oil, and lanolin to achieve deep penetration into aged leather and effective filling of fiber gaps, significantly improving the leather's softness, color, and heat resistance.

[0037] The technical solution of the present invention is further explained by using embodiments below, which are as follows:

[0038] Example 1

[0039] A method for preparing an aged leather softening agent based on lanolin / soybean polysaccharide comprises the following steps:

[0040] S1. According to the mass ratio of glycerol, amino silicone oil, lanolin and 3 wt% soybean polysaccharide aqueous solution of 2:1:1:10, glycerol, amino silicone oil, lanolin and soybean polysaccharide aqueous solution are weighed and set aside;

[0041] S2. Add the weighed 3 wt% soybean polysaccharide aqueous solution and glycerol into a three-necked flask, place the three-necked flask in a constant temperature water bath at 60° C., and stir at a speed of 1500 rpm for 30 min using an overhead stirrer to obtain a first mixture;

[0042] S3, adding the weighed amino silicone oil to the first mixture, and continuing to stir at a speed of 1500 rpm for 30 min in a constant temperature water bath at 60°C to obtain a second mixture;

[0043] S4. Dissolve the weighed lanolin at 60°C and add it dropwise to the second mixture. Use a digital high-speed disperser homogenizer to shear at a high speed of 10,000 r / min for 5 minutes. Then transfer it to a three-necked flask and heat it in a water bath at 60°C. Use an overhead stirrer to mechanically stir at 1,500 r / min for 3 hours to obtain 1# lanolin / soy polysaccharide-based aged leather softening agent.

[0044] Example 2

[0045] A method for preparing an aged leather softening agent based on lanolin / soybean polysaccharide is the same as steps S2 to S4 of Example 1, except that the mass ratio of glycerin, amino silicone oil, lanolin and 3 wt% soybean polysaccharide aqueous solution in S1 is 2:1:1:15, comprising the following steps:

[0046] S1. According to the mass ratio of glycerol, amino silicone oil, lanolin and 3 wt% soybean polysaccharide aqueous solution of 2:1:1:15, glycerol, amino silicone oil, lanolin and soybean polysaccharide aqueous solution are weighed and set aside;

[0047] S2. Add the weighed 3 wt% soybean polysaccharide aqueous solution and glycerol into a three-necked flask, place the three-necked flask in a constant temperature water bath at 60° C., and stir at a speed of 1500 rpm for 30 min using an overhead stirrer to obtain a first mixture;

[0048] S3, adding the weighed amino silicone oil to the first mixture, and continuing to stir at a speed of 1500 rpm for 30 min in a constant temperature water bath at 60°C to obtain a second mixture;

[0049] S4. Dissolve the weighed lanolin at 60°C and add it dropwise to the second mixture. Use a digital high-speed disperser homogenizer to shear at a high speed of 10,000 r / min for 5 minutes. Then transfer it to a three-necked flask and heat it in a water bath at 60°C. Use an overhead stirrer to mechanically stir at 1,500 r / min for 3 hours to obtain 2# aged leather softening agent based on lanolin / soybean polysaccharide.

[0050] Example 3

[0051] A method for preparing an aged leather softening agent based on lanolin / soybean polysaccharide is the same as steps S2 to S4 of Example 1, except that the mass ratio of glycerin, amino silicone oil, lanolin and 3 wt% soybean polysaccharide aqueous solution in S1 is 2:1:1:20, comprising the following steps:

[0052] S1. According to the mass ratio of glycerol, amino silicone oil, lanolin and 3 wt% soybean polysaccharide aqueous solution of 2:1:1:20, glycerol, amino silicone oil, lanolin and soybean polysaccharide aqueous solution are weighed and set aside;

[0053] S2. Add the weighed 3 wt% soybean polysaccharide aqueous solution and glycerol into a three-necked flask, place the three-necked flask in a constant temperature water bath at 60° C., and stir at a speed of 1500 rpm for 30 min using an overhead stirrer to obtain a first mixture;

[0054] S3, adding the weighed amino silicone oil to the first mixture, and continuing to stir at a speed of 1500 rpm for 30 min in a constant temperature water bath at 60°C to obtain a second mixture;

[0055] S4. Dissolve the weighed lanolin at 60°C and add it dropwise to the second mixture. Use a digital high-speed disperser homogenizer to shear at a high speed of 10,000 r / min for 5 minutes. Then transfer it to a three-necked flask and heat it in a water bath at 60°C. Use an overhead stirrer to mechanically stir at 1,500 r / min for 3 hours to obtain 3# aged leather softening agent based on lanolin / soybean polysaccharide.

[0056] Example 4

[0057] A method for preparing an aged leather softening agent based on lanolin / soybean polysaccharide, which has the same preparation steps as Example 1, except that the mass percentage of the soybean polysaccharide aqueous solution is replaced by 5wt% from 3wt%, comprises the following steps:

[0058] S1. According to the mass ratio of glycerol, amino silicone oil, lanolin and 3 wt% soybean polysaccharide aqueous solution of 2:1:1:10, glycerol, amino silicone oil, lanolin and soybean polysaccharide aqueous solution are weighed and set aside;

[0059] S2. Add the weighed 5 wt% soybean polysaccharide aqueous solution and glycerol into a three-necked flask, place the three-necked flask in a constant temperature water bath at 60° C., and stir at a speed of 1500 rpm for 30 minutes using an overhead stirrer to obtain a first mixture;

[0060] S3, adding the weighed amino silicone oil to the first mixture, and continuing to stir at a speed of 1500 rpm for 30 min in a constant temperature water bath at 60°C to obtain a second mixture;

[0061] S4. Dissolve the weighed lanolin at 60°C and add it dropwise to the second mixture. Use a digital high-speed disperser homogenizer to shear at 10,000 r / min for 5 minutes. Then transfer it to a three-necked flask and heat it in a water bath at 60°C. Use an overhead stirrer to mechanically stir at 1,500 r / min for 3 hours to obtain 4# aged leather softening agent based on lanolin / soybean polysaccharide.

[0062] Example 5

[0063] A method for preparing an aged leather softening agent based on lanolin / soybean polysaccharide, which has the same preparation steps as Example 2, except that the mass percentage of the soybean polysaccharide aqueous solution is replaced by 5wt% from 3wt%, comprises the following steps:

[0064] S1. According to the mass ratio of glycerol, amino silicone oil, lanolin and 3 wt% soybean polysaccharide aqueous solution of 2:1:1:15, glycerol, amino silicone oil, lanolin and soybean polysaccharide aqueous solution are weighed and set aside;

[0065] S2. Add the weighed 5 wt% soybean polysaccharide aqueous solution and glycerol into a three-necked flask, place the three-necked flask in a constant temperature water bath at 60° C., and stir at a speed of 1500 rpm for 30 minutes using an overhead stirrer to obtain a first mixture;

[0066] S3, adding the weighed amino silicone oil to the first mixture, and continuing to stir at a speed of 1500 rpm for 30 min in a constant temperature water bath at 60°C to obtain a second mixture;

[0067] S4. Dissolve the weighed lanolin at 60°C and add it dropwise to the second mixture. Use a digital high-speed disperser homogenizer to shear at 10,000 r / min for 5 minutes. Then transfer it to a three-necked flask and heat it in a water bath at 60°C. Use an overhead stirrer to mechanically stir at 1,500 r / min for 3 hours to obtain 5# aged leather softening agent based on lanolin / soybean polysaccharide.

[0068] Example 6

[0069] A method for preparing an aged leather softening agent based on lanolin / soybean polysaccharide, which has the same preparation steps as Example 3, except that the mass percentage of the soybean polysaccharide aqueous solution is replaced by 5wt% from 3wt%, comprises the following steps:

[0070] S1. According to the mass ratio of glycerol, amino silicone oil, lanolin and 5 wt% soybean polysaccharide aqueous solution of 2:1:1:20, glycerol, amino silicone oil, lanolin and soybean polysaccharide aqueous solution are weighed and set aside;

[0071] S2. Add the weighed 3 wt% soybean polysaccharide aqueous solution and glycerol into a three-necked flask, place the three-necked flask in a constant temperature water bath at 60° C., and stir at a speed of 1500 rpm for 30 min using an overhead stirrer to obtain a first mixture;

[0072] S3, adding the weighed amino silicone oil to the first mixture, and continuing to stir at a speed of 1500 rpm for 30 min in a constant temperature water bath at 60°C to obtain a second mixture;

[0073] S4. Dissolve the weighed lanolin at 60°C and add it dropwise to the second mixture. Use a digital high-speed disperser homogenizer to shear at a high speed of 10,000 r / min for 5 minutes. Then transfer it to a three-necked flask and heat it in a water bath at 60°C. Use an overhead stirrer to mechanically stir at 1,500 r / min for 3 hours to obtain 6# aged leather softening agent based on lanolin / soybean polysaccharide.

[0074] Example 7

[0075] A method for preparing an aged leather softening agent based on lanolin / soybean polysaccharide, which has the same preparation steps as Example 4, except that the mass ratio of glycerol, amino silicone oil, lanolin, and 3 wt% soybean polysaccharide aqueous solution in S1 is 2:1:1:25, and the mixing temperature of S2, S3, and S4 is changed from 60° C. to 50° C., comprising the following steps:

[0076] S1. According to the mass ratio of glycerol, amino silicone oil, lanolin and 3 wt% soybean polysaccharide aqueous solution of 2:1:1:25, glycerol, amino silicone oil, lanolin and soybean polysaccharide aqueous solution are weighed and set aside;

[0077] S2. Add the weighed 5 wt% soybean polysaccharide aqueous solution and glycerol into a three-necked flask, place the three-necked flask in a constant temperature water bath at 50° C., and stir at a speed of 1500 rpm for 30 min using an overhead stirrer to obtain a first mixture;

[0078] S3, adding the weighed amino silicone oil to the first mixture, and continuing to stir at a speed of 1500 rpm for 30 min in a constant temperature water bath at 50° C. to obtain a second mixture;

[0079] S4. Dissolve the weighed lanolin at 60°C and add it dropwise to the second mixture. Use a digital high-speed disperser homogenizer to shear at a high speed of 10,000 r / min for 5 minutes. Then transfer it to a three-necked flask and heat it in a water bath at 60°C. Use an overhead stirrer to mechanically stir at 1,500 r / min for 180 minutes to obtain 7# aged leather softening agent based on lanolin / soybean polysaccharide.

[0080] When the mass ratio of lanolin to soybean polysaccharide aqueous solution is less than 1:25, it means that the proportion of lanolin is reduced, although the particle size of the prepared lanolin / soy polysaccharide-based aged leather softening agent emulsion is reduced and evenly distributed; however, given that lanolin plays a core softening role in the lanolin / soy polysaccharide-based aged leather softening agent, the mass ratio of lanolin to soybean polysaccharide aqueous solution cannot be less than 1:25.

[0081] Comparative Example 1

[0082] A method for preparing an aged leather softening agent based on lanolin / soybean polysaccharide, which has the same preparation steps as Example 1, except that the mass percentage of the soybean polysaccharide aqueous solution in S1 is replaced by 1 wt% from 3 wt%, and the stirring time in S4 is replaced by 4 h from 3 h. The method comprises the following steps:

[0083] S1. According to the mass ratio of glycerol, amino silicone oil, lanolin and 1 wt% soybean polysaccharide aqueous solution of 2:1:1:10, glycerol, amino silicone oil, lanolin and soybean polysaccharide aqueous solution are weighed and set aside;

[0084] S2. Add the weighed 5 wt% soybean polysaccharide aqueous solution and glycerol into a three-necked flask, place the three-necked flask in a constant temperature water bath at 60° C., and stir at a speed of 1500 rpm for 30 minutes using an overhead stirrer to obtain a first mixture;

[0085] S3, adding the weighed amino silicone oil to the first mixture, and continuing to stir at a speed of 1500 rpm for 30 min in a constant temperature water bath at 60°C to obtain a second mixture;

[0086] S4. The weighed lanolin was dissolved at 60°C and added dropwise to the second mixture. A digital high-speed disperser homogenizer was used to shear the mixture at 10,000 r / min for 5 minutes. The mixture was then transferred to a three-necked flask and heated in a water bath at 60°C. An overhead stirrer was used to mechanically stir the mixture at 1,500 r / min for 4 hours. The emulsion stratification was severe.

[0087] Comparative Example 2

[0088] A method for preparing an aged leather softening agent based on lanolin / soybean polysaccharide, which has the same preparation steps as those in Comparative Example 1, except that the mass percentage of the soybean polysaccharide aqueous solution in S1 is replaced by 10 wt % from 1 wt %, comprises the following steps:

[0089] S1. According to the mass ratio of glycerol, amino silicone oil, lanolin and 10 wt% soybean polysaccharide aqueous solution of 2:1:1:10, glycerol, amino silicone oil, lanolin and soybean polysaccharide aqueous solution are weighed and set aside;

[0090] S2. Add the weighed 5 wt% soybean polysaccharide aqueous solution and glycerol into a three-necked flask, place the three-necked flask in a constant temperature water bath at 60° C., and stir at a speed of 1500 rpm for 30 minutes using an overhead stirrer to obtain a first mixture;

[0091] S3, adding the weighed amino silicone oil to the first mixture, and continuing to stir at a speed of 1500 rpm for 30 min in a constant temperature water bath at 60°C to obtain a second mixture;

[0092] S4. Dissolve the weighed lanolin at 60°C and add it dropwise to the second mixture. Use a digital high-speed dispersing homogenizer to shear at 10,000 rpm for 5 minutes. Then transfer the mixture to a three-necked flask and heat in a 60°C water bath with mechanical stirring at 1,500 rpm for 180 minutes using an overhead stirrer to obtain 8# lanolin / soy polysaccharide-based aged leather softening agent. The particle size of the 8# lanolin / soy polysaccharide-based aged leather softening agent emulsion is too large, making it difficult to penetrate into the leather.

[0093] Comparative Example 3

[0094] A method for preparing an aged leather softening agent based on lanolin / soybean polysaccharide, which has the same preparation steps as Comparative Example 2, except that the mass ratio of glycerin, amino silicone oil, lanolin and 10 wt% soybean polysaccharide aqueous solution in S1 is 2:1:1:20, comprising the following steps:

[0095] S1. According to the mass ratio of glycerol, amino silicone oil, lanolin and 10 wt% soybean polysaccharide aqueous solution of 2:1:1:20, glycerol, amino silicone oil, lanolin and soybean polysaccharide aqueous solution are weighed and set aside;

[0096] S2. Add the weighed 5 wt% soybean polysaccharide aqueous solution and glycerol into a three-necked flask, place the three-necked flask in a constant temperature water bath at 60° C., and stir at a speed of 1500 rpm for 30 minutes using an overhead stirrer to obtain a first mixture;

[0097] S3, adding the weighed amino silicone oil to the first mixture, and continuing to stir at a speed of 1500 rpm for 30 min in a constant temperature water bath at 60°C to obtain a second mixture;

[0098] S4. Dissolve the weighed lanolin at 60°C and add it dropwise to the second mixture. Use a digital high-speed dispersing homogenizer to shear at 10,000 rpm for 5 minutes. Then transfer the mixture to a three-necked flask, heat in a 60°C water bath, and mechanically stir at 1,500 rpm for 180 minutes using an overhead stirrer to obtain a lanolin / soy polysaccharide-based aged leather softening agent #9. The average particle size of the lanolin / soy polysaccharide-based aged leather softening agent emulsion #9 is too large, making it difficult to penetrate the leather.

[0099] Figure 1 The particle size distribution diagram of the soybean polysaccharide aqueous solution used in the present invention is shown in FIG. Figure 1 The particle size distribution of the soy polysaccharide aqueous solution is concentrated in two ranges: 0.05μm-0.12μm and 0.31μm-0.89μm. The particle size distribution diagram of the soy polysaccharide aqueous solution shows that the particle size of the soy polysaccharide aqueous solution used this time is a small amount in the range of 0.05μm-0.12μm, and the majority is concentrated in the range of 0.31μm-0.89μm.

[0100] Figure 2 This is the infrared spectrum of soybean polysaccharide used in the present invention. Figure 2 It was found that soybean polysaccharide showed characteristic absorption peaks of polysaccharides, and the -OH stretching vibration peak appeared at 3422 cm -1 Nearby. 2928cm -1 The characteristic absorption peak near the C—H stretching vibration is relatively weak. The uronic acid group appears at 1730 cm -1The C=O absorption peak at 1628 cm -1 Absorption peak near 1073cm -1 The peaks nearby are the vibration peaks of COC. The infrared spectrum results show that the characteristic functional groups of soybean polysaccharides are aldehyde, ester and hydroxyl groups.

[0101] Depend on Figure 3 It is known from (a)(a1)(b)(b1)(c)(c1) that when the mass percentage of the soybean polysaccharide aqueous solution is 3wt%, the particle size distribution of the aged leather softening agent based on lanolin / soybean polysaccharide is in the range of 1.7μm to 32.2μm. As the amount of lanolin decreases, the particle size of the prepared aged leather softening agent based on lanolin / soybean polysaccharide decreases, and the uniformity of the particle size distribution increases; when the mass ratio of lanolin to soybean polysaccharide aqueous solution is 1:10, the particle size distribution is 1.7μm to 32.2μm; when the mass ratio of lanolin to soybean polysaccharide aqueous solution is 1:20, the particle size distribution is 6μm to 24μm;

[0102] Depend on Figure 3 (d)(d1)(e)(e1)(f)(f1) in the figure show that when the mass percentage of the soybean polysaccharide aqueous solution is 5wt%, the particle size distribution range of the aged leather softening agent based on lanolin / soybean polysaccharide is 5.0μm to 31.6μm. As the oil phase content decreases, the particle size of the prepared aged leather softening agent based on lanolin / soybean polysaccharide changes slightly and the particle size distribution becomes uniform; when the mass ratio of lanolin to soybean polysaccharide aqueous solution is 1:10, the particle size distribution is 6.4μm to 31.6μm; when the mass ratio of lanolin to soybean polysaccharide aqueous solution is 1:20, the particle size distribution is 5μm to 24μm;

[0103] Depend on Figure 3 It can be seen from (g)(g1)(h)(h1) that when the mass percentage of the soybean polysaccharide aqueous solution is 10wt%, the particle size distribution range of the aged leather softening agent based on lanolin / soybean polysaccharide is 17.3μm~32.2μm; with the increase of soybean polysaccharide content, the particle size of the prepared aged leather softening agent based on lanolin / soybean polysaccharide becomes slightly smaller and the particle size distribution becomes uniform; when the mass ratio of lanolin to soybean polysaccharide aqueous solution is 1:10, the particle size distribution is 20.5μm~32.2μm; when the mass ratio of lanolin to soybean polysaccharide aqueous solution is 1:20, the particle size distribution is 17.3μm~27.8μm.

[0104] Depend on Figure 3 It can be observed from (a2)(b2)(c2)(d2)(e2)(f2)(g2)(h2) that the aged leather softening agent based on lanolin / soybean polysaccharide prepared by the present invention is a uniform and stable emulsion.

[0105] The softening agent obtained in Examples 1 to 6 of the present invention is used as an example to apply it to the softening of aged leather. The specific application method and results are as follows:

[0106] (1) Preparation of aged leather samples

[0107] S1. Weighing: Cut the sheepskin, weigh it and record the weight. Use a wide range pH test paper to test the pH value of the acid-soaked leather surface and record it (pH = 2-3).

[0108] S2. Salting the sample: Use an electronic balance to weigh 7 wt% of the sheepskin's sodium chloride (NaCl) and place it in two 1000 mL beakers. Add 200 wt% deionized water to each beaker. Then place the corresponding sheepskin in the solution and shake it in a constant temperature water bath at 30°C for 1 hour. The purpose of salting is to prevent acid swelling.

[0109] S3. Deacidification: Pour away the salt solution, weigh 2 wt% of the sheepskin weight of sodium thiosulfate Na2S2O3 using an electronic balance, and oscillate at a constant temperature of 30°C for 30 minutes in a liquid-free state. Deacidify until the pH value of the leather surface reaches 4-5 as measured by pH test paper. The deacidification time is 30 minutes. Under these conditions, the structure of the sheepskin is conducive to the entry of rubber bowl tannin into the leather fibers for tanning.

[0110] S4. Tanning: ① Using an electronic balance, weigh 10 wt% of the sheepskin's weight of rubber bowl extract into a beaker, then place the sheepskin into the tanning solution and shake under the same conditions for 2 days until the tanning agent becomes lighter in color; ② Using an electronic balance, weigh 15 wt% of the sheepskin's weight of rubber bowl extract into the beaker, and continue shaking under the same conditions for 4 days until the tanning agent becomes lighter in color; ③ Using an electronic balance, weigh 20 wt% of the sheepskin's weight of rubber bowl extract into the beaker, and shake under the same temperature for 9 days until the sheepskin cross section is uniform in color, i.e., tanned thoroughly.

[0111] S5. Rinse: Rinse the leather in distilled water for 30 minutes, changing the water every 10 minutes. Rub the leather during the rinse to remove any excess tannins not involved in the tanning process. Place the leather sample in a ventilated and dry place and allow it to dry naturally before use.

[0112] S6. Aging: setting the oven temperature to 120° C. and aging the sample for 8 days to obtain an aged rubber-tanned leather sample.

[0113] (2) Softening of aged rubber-tanned leather samples

[0114] Use brushing method to soften, the specific method is as follows:

[0115] First, moisten the aged rubber-tanned leather sample with distilled water for 30 minutes to soften it, then use a brush to dip the softener and apply it to its surface. After the aged rubber-tanned leather sample has completely absorbed the softener, apply it again until the quality of the aged rubber-tanned leather sample no longer changes. Each time, leave an interval of 20 minutes, and then place it in a ventilated environment to dry naturally.

[0116] (3) Characterization of properties of aged rubber-tanned leather samples before and after softening

[0117] a. Differential Scanning Calorimetry (DSC) Test: This experiment measured DSC using a differential scanning calorimeter model 214Polyma from NETZSCH Instrument Co., Ltd. in Germany. The heating rate was set at 10°C / min, the heating range was 25°C to 250°C, the protective gas flow rate P2 (N2) was 40 mL / min, and the furnace protective gas flow rate PG (N2) was 60 mL / min; the protective gas was N2.

[0118] b. Thermogravimetric analysis: Thermogravimetric analysis of the present invention uses a thermogravimetric analyzer model 209F3Tarsus from NETZSCH Instruments GmbH, Germany, with a heating rate of 10°C / min, a heating range of 40°C to 600°C, a protective gas flow rate P2 of 50 mL / min, and a furnace protective gas flow rate PG of 20 mL / min; wherein the protective gas is N2.

[0119] c. Color Difference Test: Using an aged, pre-softening rubber-tanned leather sample as a baseline, analyze the color difference and color difference changes between the aged, pre-softening, and post-softening samples. A high-precision colorimeter (JZ-600, manufactured by Jinzhun Technology Hong Kong Ltd.) was used, with an unaged, pre-softening rubber-tanned leather sample as a blank. Zero-point and white-plate calibration were performed before measurement, and the color difference of the grain surface of the rubber-tanned leather sample was measured. Three different test points were taken for each sample, protected from light during measurement. The measured lightness (L*), color difference (a, b), and color difference ΔE were recorded, calculated as shown in Equation 1, and the resulting data were averaged.

[0120]

[0121] In order to further analyze the effect of softening on leather color, the present invention uses a high-precision colorimeter to measure the brightness and chromaticity of the samples before and after softening, and calculates the brightness difference (ΔL), chromaticity difference (Δa, Δb) and overall color difference (ΔE) before and after softening.

[0122] d. Softness Test: A GT-303-D leather softness tester was used to measure the softness of the grain layer of the aged rubber-tanned leather samples. Calibration was performed using standard iron and leather sheets before measurement. Three different test points were taken for each aged rubber-tanned leather sample, and the softness data were recorded. The average of the obtained data was used as the softness of the aged rubber-tanned leather sample to analyze the change in softness before and after softening.

[0123] One of the most important properties of leather products is softness. The softness of leather is usually determined by the amount of space the collagen fibers have to move and how easily they can slide relative to each other.

[0124] Depend on Figure 4 (a) It is known that as the proportion of oil phase decreases, its softness first decreases and then increases; Figure 4 Results (b) show that for a lanolin / soy polysaccharide-based softening agent for aged leather prepared with a 5 wt% soy polysaccharide aqueous solution, the softness restoration effect after softening deteriorates as the mass ratio of lanolin to soy polysaccharide aqueous solution decreases. This is because the high soy polysaccharide concentration and excessive oil content in the lanolin / soy polysaccharide-based softening agent for aged leather prevent the softening agent from fully penetrating the leather fibers, resulting in clogging on the surface and poor leather softness restoration. By comparing the softness of aged rubber-tanned leather samples before and after softening, it was found that the softness of the aged rubber-tanned leather samples was greatly improved after using the aged leather softening agent based on lanolin / soy polysaccharide, indicating that the aged leather softening agent based on lanolin / soy polysaccharide can repair the leather caking phenomenon; compared with 1#, 2# and 3# aged leather softening agents based on lanolin / soy polysaccharide prepared with 3wt% soy polysaccharide, 4#, 5# and 6# aged leather softening agents based on lanolin / soy polysaccharide prepared with 5wt% soy polysaccharide have better effect on restoring softness.

[0125] Depend on Figure 5 It was observed that the glossiness of the surface of the aged rubber-tanned leather samples was significantly improved after softening, but the color of the aged rubber-tanned leather samples was deepened to varying degrees after softening.

[0126] Depend on Figure 6 It was found that after softening, ΔL was a positive value, indicating that the color of the leather darkened after softening, and the concentration of soybean polysaccharide remained unchanged. The softening agent prepared by changing the oil phase and water phase had different effects on the color. Reducing the oil phase content, that is, when the mass ratio of lanolin to soybean polysaccharide aqueous solution was 1:20, the color change before and after softening was reduced.

[0127] contrast Figure 6 (a) and Figure 6(b) It was found that the softening agent prepared using 3 wt% soy polysaccharide had a smaller effect on the color of rubber-tanned leather than the softening agent prepared using 5 wt% soy polysaccharide. Looking only at the yellowness change Δb, the lanolin / soy polysaccharide-based softening agent for aged leather of the present invention has a yellowish tint due to the presence of lanolin, resulting in a smaller change in yellowness before and after softening. This indicates that the lanolin / soy polysaccharide-based softening agent for aged leather of the present invention is effective in changing the surface color of leather. In terms of color change, the lanolin / soy polysaccharide-based softening agent for aged leather of Example 3 has the best softening effect.

[0128] Depend on Figure 7 It was learned that the pyrolysis of aged rubber-tanned leather samples was divided into three stages: first, within 120°C, the volatile small molecular components inside the aged rubber-tanned leather samples began to evaporate; then, the quality of the aged rubber-tanned leather samples rapidly decreased. This was because the fibers of the aged rubber-tanned leather samples decomposed rapidly when heated between 250°C and 450°C. This stage was the main pyrolysis stage; finally, when the temperature exceeded 500°C, the quality decline became slow. This stage was mainly due to the further carbonization of the aged rubber-tanned leather samples at high temperatures.

[0129] By comparing the TG curves before and after softening, we can see that the stage of rapid weight loss of aged rubber-tanned leather samples after softening is advanced to varying degrees. This is because volatile oils fill the gaps between the fibers of the aged rubber-tanned leather samples during the softening period, which increases the amount of volatile small molecules in the aged rubber-tanned leather samples after softening. However, the temperature corresponding to the maximum weight loss rate of the aged rubber-tanned leather samples before and after softening does not change significantly, and is approximately 320°C. Moreover, Figure 7 It can be seen from (d) in that the maximum weight loss rate decreased after softening, that is, the peak value of the DTG curve decreased, indicating that the aged rubber-tanned leather sample restored the thermal stability. This shows that the aged leather softening agent based on lanolin / soybean polysaccharide prepared by the present invention did not have an adverse effect on the thermal stability of the aged rubber-tanned leather sample.

[0130] Depend on Figure 8 The DSC curve of the aged rubber-tanned leather sample showed two endothermic peaks at 75°C and 220°C, respectively. The peak at 75°C, or T1, is related to the thermal shrinkage temperature of the aged rubber-tanned leather sample. The higher this temperature, the better the thermal stability of the aged rubber-tanned leather sample. After softening with softening agents 3#, 4#, and 5#, this peak shifted to higher temperatures, indicating improved thermal stability of the aged rubber-tanned leather sample. The T2 temperature corresponds to the decomposition of collagen structure. After softening, the softening agent penetrates and fills the spaces between collagen fibers, increasing the spacing between them and disrupting the local order of the collagen fibers, causing the endothermic peak at this location to disappear.

[0131] Obviously, those skilled in the art may make various changes and modifications to the present invention without departing from the spirit and scope of the present invention. Thus, if such changes and modifications fall within the scope of the claims and their equivalents, the present invention is intended to include such changes and modifications.

Claims

1. A lanolin / soybean polysaccharide-based aging leather softening agent, characterized in that: The softening agent is prepared by mixing glycerin, amino silicone oil, lanolin and soybean polysaccharide aqueous solution, and the mass ratio of glycerin, amino silicone oil, lanolin and soybean polysaccharide aqueous solution is 2:1:1:10-25; The mass percentage of the soybean polysaccharide aqueous solution is 3wt% to 5wt%.

2. A method for preparing the aged leather softening agent based on lanolin / soybean polysaccharide according to claim 1, characterized in that: The following steps are involved: mixing the soybean polysaccharide aqueous solution and glycerol to obtain a first mixture; adding amino silicone oil to the first mixture and mixing to obtain a second mixture; The melted lanolin is added to the second mixture and mixed to obtain an aged leather softening agent based on lanolin / soybean polysaccharide.

3. A method for preparing an aged leather softening agent based on lanolin / soybean polysaccharide according to claim 2, characterized in that: When preparing the first mixture, the mixing temperature is 50° C. to 60° C., and the mixing time is 15 min to 30 min.

4. The method for preparing an aged leather softening agent based on lanolin / soybean polysaccharide according to claim 2, wherein: When preparing the second mixture, the mixing temperature is 50° C. to 60° C., and the mixing time is 15 min to 30 min.

5. The method for preparing an aged leather softening agent based on lanolin / soybean polysaccharide according to claim 2, wherein: The melted lanolin is added to the second mixture and mixed at a temperature of 50°C to 60°C for 150 minutes to 180 minutes.

6. Use of the lanolin / soybean polysaccharide-based aged leather softening agent according to claim 1 in softening aged leather.

7. The application of the lanolin / soybean polysaccharide-based aged leather softening agent in the softening of aged leather according to claim 6, characterized in that: Apply the aged leather softening agent based on lanolin / soy polysaccharide to the aged leather surface and let it dry.

8. The application of the lanolin / soybean polysaccharide-based aged leather softening agent in the softening of aged leather according to claim 6, characterized in that: Repeatedly apply the aged leather surface with a lanolin / soy polysaccharide-based aged leather softener until the quality of the aged leather no longer changes.

9. The application of the lanolin / soybean polysaccharide-based aged leather softening agent in the softening of aged leather according to claim 7, characterized in that: Before applying the aged leather softener based on lanolin / soy polysaccharide, moisten the aged leather with distilled water.

Images