A leather surface treatment agent and preparation method thereof

Abstract

The present invention relates to the technical field of leather surface treatment agents, and in particular to a leather surface treatment agent and a preparation method thereof. A leather surface treatment agent comprises the following raw materials: 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-40 parts of hydrogen-containing silicone oil, 0.2-2 parts of polyether-modified silicone oil, 3-20 parts of epoxy-modified hydrogen-containing silicone oil, 10-50 parts of matting powder, 10-50 parts of PU resin, 200-800 parts of mixed solvent, 1-10 parts of coupling agent, and 0.2-5 parts of catalyst. This scheme solves the technical problem that the bonding performance of silicone leather surface treatment agent is not ideal. When used, the surface treatment agent is applied on the surface of polyurethane synthetic leather, and then the surface-treated polyurethane synthetic leather is obtained by baking. The leather surface treatment agent prepared by the invention has the characteristics of excellent hand feel, good antifouling performance, good adhesion, moisture and heat resistance, boiling resistance, and UV resistance, and has ideal promotion and application value.

Description

Technical Field

[0001] The invention relates to the technical field of leather surface treatment agents, and in particular to a leather surface treatment agent and a preparation method thereof. Background Art

[0002] Leather materials have been widely used in many fields such as automobiles, aviation, medical treatment, clothing, luggage, furniture, decoration, etc. due to their good physical and mechanical properties, excellent hygiene properties, and exquisite appearance and texture. They are closely related to people's daily life, work, travel and other aspects, and have become indispensable materials. According to the source of the material, leather materials are generally divided into two categories: natural leather and artificial leather. At present, the annual production and sales volume of artificial leather in my country is about 4 billion square meters, accounting for about 60% of the global total. Among them, PU synthetic leather accounts for more than 60% of artificial leather, reaching more than 2.5 billion square meters, due to its advantages in appearance and texture close to genuine leather, high strength and low cost. PU synthetic leather needs to be surface treated after leather making to improve the surface touch, adjust the surface light haze, and enhance customer experience. At present, the leather surface treatment agent is mainly PU material. The use of PU surface treatment agent can obtain ideal light haze and improve the leather touch to a certain extent, but it cannot meet people's needs for leather skin-friendly feel and anti-fouling performance. Therefore, some studies have tried to use silicone materials for the surface treatment of PU synthetic leather, which can effectively improve the skin-friendly feel and anti-fouling performance of PU synthetic leather. However, the surface energy of silicone materials is relatively low, the bonding performance is poor, and the bonding ability with PU materials is weak. General surface treatment agents need to be quickly cured and bonded at high temperatures, and the film thickness of the surface treatment agent is thin (below 50 microns), which brings difficulties to the research and development of surface treatment agents containing silicone materials. In addition, it is difficult to solve the bonding problem by adding coupling agents, which has hindered the development of silicone leather surface treatment agents. Therefore, it is urgent to develop a silicone leather surface treatment agent with good bonding properties, thereby improving the skin-friendly feel and anti-fouling properties of the PU leather surface. The successful development of such products will have broad prospects for application and promotion. Summary of the invention

[0003] The present invention aims to provide a leather surface treatment agent to solve the technical problems that the organic silicon leather surface treatment agent in the prior art has unsatisfactory bonding performance, and its skin affinity and antifouling properties need to be further improved.

[0004] In order to achieve the above object, the present invention adopts the following technical scheme:

[0005] A leather surface treatment agent comprises the following raw materials, measured by weight: 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-40 parts of hydrogen-containing silicone oil, 0.2-2 parts of polyether-modified silicone oil, 3-20 parts of epoxy-modified hydrogen-containing silicone oil, 10-50 parts of matting powder, 10-50 parts of PU resin, 200-800 parts of mixed solvent, 1-10 parts of coupling agent and 0.2-5 parts of catalyst.

[0006] The technical solution also provides a method for preparing a leather surface treatment agent, comprising the following steps performed in sequence:

[0007] S1: mixing hydroxyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, polyether-modified silicone oil, epoxy-modified hydrogen-containing silicone oil, matting powder, and type A solvent to obtain system I;

[0008] S2: Mix the PU resin and the type B solvent, and then add them to the system I to obtain the system II;

[0009] S3: Add a coupling agent and a catalyst to system II to obtain a leather surface treatment agent.

[0010] The technical solution also provides a method for applying a leather surface treatment agent, wherein the leather surface treatment agent is coated on the surface of polyurethane synthetic leather, and then baked at 130-170° C. for 3-5 minutes to obtain the surface-treated polyurethane synthetic leather.

[0011] Furthermore, the hydroxyl content of the hydroxyl-terminated polydimethylsiloxane is 0.03-0.3wt%, and the viscosity is 2000-1000000mPa·s. The type, hydroxyl content, viscosity and ratio of the hydroxyl-terminated polydimethylsiloxane to the PU resin have an important influence on the self-stratification performance, antifouling performance, feel and adhesion of the surface treatment agent. Too high an amount of PU resin added will lead to too high a PU component content, poor self-stratification performance, antifouling and poor feel, and too low an amount of PU resin added will lead to poor adhesion.

[0012] Furthermore, the hydrogen-containing silicone oil is a side-chain hydrogen-containing silicone oil with a viscosity of 30-500 mPa·s and a hydrogen content of 0.3-1.2 wt%.

[0013] Furthermore, the viscosity of the polyether-modified silicone oil is 30-200 mPa·s, and its structural formula is shown in formula (1);

[0014]

[0015] Formula (1)

[0016] Wherein, m+n is an integer of 10-50, and n / (m+n) is 50-100%; a+b is an integer of 8-30.

[0017] Use polyether modified silicone oil as a dispersing aid to keep the surface treatment agent stable during the construction process (in the material tank), so that the surface treatment agent will not phase separate during the construction process. The preferred polyether modified silicone oil has a viscosity of 30 to 200 mPa·s. Viscosity that is too high or too low will affect the stability of the surface treatment agent during construction.

[0018] Furthermore, the epoxy-modified hydrogenated silicone oil has a hydrogen content of 0.2-1.0 wt %, an epoxy group content of 3-14 wt %, and a viscosity of 100-5000 mPa·s.

[0019] Furthermore, the structural formula of the epoxy-modified hydrogenated silicone oil is shown in formula (2);

[0020]

[0021] Formula (2)

[0022] Wherein, R is a hydrogen group, a methyl group or a glycidoxypropyl group, and n is an integer of 30-100.

[0023] In this technical solution, the use of epoxy-modified hydrogenated silicone oil can improve the stability of the blended organic silicon material and PU resin and the bonding performance of the polyurethane layer interface. The inventor analyzed that the reason is that the silicon hydrogen in the epoxy-modified hydrogenated silicone oil reacts with the hydroxyl group in the organic silicon component, and the epoxy reacts with the amino group in the PU resin component, thereby achieving the improvement of product performance. In addition, the mixed use of epoxy-modified hydrogenated silicone oil and general hydrogenated silicone oil also improves the product appearance, reduces surface defects, and improves anti-fouling ability and surface feel.

[0024] In epoxy-modified hydrogenated silicone oil, the mass fraction of hydrogen mainly affects the crosslinking density of the surface treatment agent. When the crosslinking density is high, the colloid is brittle, and when the crosslinking density is low, the colloid strength is low. Experimental verification shows that the mass fraction of hydrogen is more suitable at 0.2% to 1.0%. The mass fraction of epoxy groups mainly affects the bonding strength between the organosilicon component and the polyurethane component in the surface treatment agent. When the mass fraction of epoxy is too high, the synthesis of epoxy-modified hydrogenated silicone oil is more difficult due to the steric effect of the epoxy side group. When the mass fraction of epoxy groups is too low, the bonding strength between the organosilicon component and the polyurethane component in the surface treatment agent is affected. Experimental verification shows that the mass fraction of epoxy is 3% to 14%.

[0025] Furthermore, the mixed solvent consists of a Class A solvent and a Class B solvent; the Class A solvent includes at least one of petroleum ether, white spirit and isoparaffin; and the Class B solvent includes at least one of acetone, methyl acetate, ethyl acetate and butyl acetate.

[0026] The use of appropriate solvent types and appropriate preparation processes will affect the dispersion effect of the surface treatment agent, as well as the adhesion performance between the surface treatment agent and polyurethane synthetic leather, as well as the appearance, anti-fouling properties and feel.

[0027] Furthermore, the coupling agent includes at least one of KH-540, KH-550, KH-560, KH-570, and KH-792; and the catalyst is chelated tin.

[0028] The principle of this technical solution is as follows:

[0029] The non-silicone surface treatment agents in the prior art have the problem of poor skin affinity and anti-fouling performance, while the silicone surface treatment agents have the problem of poor adhesion to the leather surface. In view of the above problems, the inventors have studied and developed new surface treatment agents. In this technical solution, the research and development difficulty is mainly to solve the problem of poor adhesion between silicone and PU. The traditional solution to adhesion is to add 1-3% coupling agent, but because the film thickness of the surface treatment agent is less than 50 microns, such a small amount of coupling agent is difficult to achieve a bonding effect, and during the high-temperature rapid curing process, the coupling agent is difficult to migrate to the bonding interface and has no bonding effect. In this technical solution, the inventors blended the silicone material with the PU resin to prepare a self-stratified leather surface treatment agent. During the curing process, the silicone material and the PU resin are gradually stratified to form a surface treatment agent layer with the silicone material as the surface layer and the PU resin as the bottom layer. The silicone layer provides skin-friendly feel and anti-fouling performance, and the PU layer provides adhesion to the PU leather.

[0030] How to add PU resin to silicone material, thereby improving the bonding strength between the surface modification layer of silicone material and polyurethane synthetic leather, and improving the appearance, antifouling performance and feel of the product. The technical points are as follows: polyether modified silicone oil, epoxy modified hydrogenated silicone oil and hydrogenated silicone oil need to be added to the silicone material at the same time, and Class A solvent needs to be blended with silicone material, and Class B material needs to be blended with PU resin. Controlling the above technical points during the production process can ensure that the surface modification layer of the silicone material of the product is firmly bonded to the polyurethane synthetic leather, and has strong waterproof, heat-resistant, acid-resistant and UV-resistant properties. DETAILED DESCRIPTION

[0031] The present invention is further described in detail below in conjunction with examples, but the embodiments of the present invention are not limited thereto. Unless otherwise specified, the technical means used in the following examples and experimental examples are conventional means well known to those skilled in the art, and the materials, reagents, etc. used can be obtained from commercial sources.

[0032] The basic information of leather surface treatment agent and preparation method is as follows:

[0033] (1) The formula of the leather surface treatment agent of this scheme is as follows:

[0034] The raw materials include, by mass, 100 parts of hydroxyl-terminated polydimethylsiloxane, 10-40 parts of hydrogen-containing silicone oil, 0.2-2 parts of polyether-modified silicone oil, 3-20 parts of epoxy-modified hydrogen-containing silicone oil, 10-50 parts of matting powder, 10-50 parts of PU resin, 200-800 parts of mixed solvent, 1-10 parts of coupling agent and 0.2-5 parts of catalyst.

[0035] The viscosity of the hydroxyl-terminated polydimethylsiloxane is 2000-1000000 mPa·s (tested under standard conditions), and the hydroxyl content is 0.03%-0.3%.

[0036] The hydrogen-containing silicone oil is a side chain hydrogen-containing silicone oil with a viscosity of 30-500 mPa·s and a hydrogen content of 0.3-1.2 wt%;

[0037] The viscosity of the polyether modified silicone oil is 30-200 mPa·s, and the structural formula is shown in formula (1), m and n are integers, m+n ranges from 10-50, n / (m+n) is 50-100%, a and b are integers, a+b ranges from 8-30, and there is no special requirement for the ratio of a to b.

[0038]

[0039] Formula (1)

[0040] Epoxy-modified hydrogenated silicone oil: hydrogen content is 0.2-1.0 wt %, epoxy group content is 3-14 wt %, viscosity is 100-5000 mPa·s, and the structure is shown in formula (2), wherein R is hydrogen, methyl or glycidoxypropyl, and n is an integer of 30-100.

[0041]

[0042] Formula (2)

[0043] The mixed solvent is composed of a Class A solvent and a Class B solvent. The Class A solvent is at least one of petroleum ether, white spirit and isoparaffin; the Class B solvent is at least one of acetone, methyl acetate, ethyl acetate and butyl acetate. The mass fraction of each specific solvent in the mixed solvent is not less than 10%.

[0044] The coupling agent is at least one of KH-540, KH-550, KH-560, KH-570, and KH-792.

[0045] The catalyst is chelated tin commonly used in the prior art.

[0046] (2) The preparation method of the leather surface treatment agent is as follows:

[0047] Step 1: Add hydroxyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, polyether-modified silicone oil, epoxy-modified hydrogen-containing silicone oil, matting powder, and Class A solvent into a high-speed disperser and stir evenly to obtain system I.

[0048] Step 2: Mix and stir the PU resin and the type B solvent, then add them into system I and stir evenly to obtain system II.

[0049] Step 3: Add coupling agent and catalyst to system II, stir evenly, filter impurities to obtain leather surface treatment agent.

[0050] (3) The construction method of the leather surface treatment agent is as follows:

[0051] Use a gravure printing machine to apply a leather surface treatment agent on the surface of the polyurethane synthetic leather (the polyurethane leather uses the polyurethane leather sold by Sichuan Feida), with a coating amount of 15-30 grams per square meter, and bake at 130-170° C. for 3-5 minutes to obtain the surface-treated polyurethane synthetic leather.

[0052] The material selection and parameter settings of Examples 1 to 6 are shown in Table 1.

[0053] Table 1: Material selection and parameter settings for Examples 1 to 6

[0054]

[0055]

[0056] The difference between Comparative Example 1 and Example 6 is that no polyether-modified silicone oil is added.

[0057] The difference between Comparative Example 2 and Example 6 is that the epoxy-modified hydrogen-containing silicone oil is replaced by hydrogen-containing silicone oil of the same mass with the same hydrogen content, that is, "④ 15 parts of epoxy-modified hydrogen-containing silicone oil (hydrogen content 1.0%, epoxy group mass fraction of 5%, viscosity 500mPa·s)" is replaced by "④ 15 parts of hydrogen-containing silicone oil (hydrogen content 1.0%, viscosity 500mPa·s)".

[0058] The difference between Comparative Example 3 and Example 6 is that the solvent is all isoparaffin ISOPAR E, which is divided into two parts with a ratio of 1:1 and added to step 1 and step 2 respectively.

[0059] The difference between Comparative Example 4 and Example 6 is that no PU resin is added. In the preparation process, step 2 is omitted, and the type B solvent is directly added in step 1.

[0060] The difference between Comparative Example 5 and Example 6 is that the type A and type B solvents and the PU resin are all added in step 1, and step 2 is omitted.

[0061] The difference between Comparative Example 6 and Example 6 is that the hydrogen-containing silicone oil is replaced by the same mass of epoxy-modified hydrogen-containing silicone oil with the same hydrogen content, that is, "② 10 parts of hydrogen-containing silicone oil (hydrogen content: 1.2%, viscosity 500mPa·s)" is replaced by "② 10 parts of epoxy-modified hydrogen-containing silicone oil (hydrogen content: 1.2%, epoxy group mass fraction is 5%, viscosity 500mPa·s)".

[0062] Experimental example:

[0063] The following performance tests were conducted on the polyurethane synthetic leather treated with the self-delamination leather surface treatment agent. The test methods are as follows.

[0064] (1) Appearance test

[0065] Observe under strong light to see if there are any flaws on the surface of the treated leather. The evaluation criteria are as follows:

[0066] Level 1: flawless;

[0067] Level 2 slight defect (with defective spots);

[0068] Level 3: Large defects (with bright stripes);

[0069] Level 4 has more flaws in appearance.

[0070] (2) Antifouling test

[0071] According to the provisions of ASTM D1308-02, the experiment was conducted using oily pens, chili oil, beverages, and ballpoint pens to test the antifouling performance. The test time was 15 minutes, 1 hour, 2 hours, 8 hours, and 24 hours. The evaluation standards are as follows:

[0072] Level 1 stains were not removed at all;

[0073] Level 2 stains are almost all still there;

[0074] Level 3 light stains;

[0075] Level 4 leaves no stains.

[0076] (3) Hand feel test

[0077] Touch the treated leather surface with your hands to judge the feel. The evaluation criteria are as follows:

[0078] Level 1: smooth;

[0079] Level 2 is smoother;

[0080] Level 3: General;

[0081] Level 4 is poor.

[0082] (4) Folding fastness

[0083] The test was carried out according to the method specified in QB / T 2714. The folding fastness was tested. The leather condition was observed every 5,000 times to see if there was any delamination or cracking on the leather surface. The highest number of foldings without cracking or delamination was recorded. The test was carried out up to 100,000 times.

[0084] (5) Folding fastness after boiling

[0085] After the leather is boiled in 85℃ hot water for 5 days, it is tested according to the method specified in QB / T 2714 to test the folding fastness. The state of the leather is observed every 5,000 times to see if there is any powdering or cracking on the leather surface. The highest number of foldings without cracking or powdering is recorded. The test is up to 100,000 times.

[0086] (6) Folding fastness after salt spray aging

[0087] After the leather is corroded in a salt spray aging test chamber for 1000 hours, it is tested according to the method specified in QB / T 2714 to test the folding fastness. The state of the leather is observed every 5,000 times to see if there is any powdering or cracking on the leather surface. The highest number of foldings without cracking or delamination is recorded, and the test is tested up to 100,000 times.

[0088] (7) Folding fastness after UV aging

[0089] After the leather is treated in a UV aging test chamber for 48 hours, it is tested according to the method specified in QB / T 2714 to test the folding fastness. The leather state is observed every 5,000 times to see if there is any powdering or cracking on the leather surface. The highest number of foldings without cracking or delamination is recorded, and the test is tested up to 100,000 times.

[0090] The experimental results of the above (1)-(7) are shown in Table 2. It can be seen that the schemes of Examples 1-6 can all prepare leather surface treatment agents with better effects.

[0091] The surface-treated polyurethane synthetic leather of Comparative Example 4 performed well in the appearance test, antifouling test and hand feel test, but due to the lack of PU resin, the adhesion to the polyurethane leather was poor, so it was easy to lose powder and delaminate in the folding test, and the water resistance, high temperature resistance, acid resistance and ultraviolet radiation resistance of the surface treatment layer were not ideal. Comparison of the experimental data of Comparative Example 4 and Example 6 shows the importance of adding PU resin to the silicone material. The silicone layer can provide skin-friendly hand feel and antifouling performance, and the PU layer can provide adhesion to the PU leather.

[0092] Although adding PU resin to the organosilicon material can improve the bonding strength between the surface modified layer of the organosilicon material and the polyurethane synthetic leather, not any PU resin addition method can achieve the desired effect. How to effectively combine the organosilicon material and the PU resin is a problem that the inventor has studied extensively.

[0093] First, adding silicone oil to the organosilicon material (hydroxy-terminated polydimethylsiloxane), as well as the type and proportion of silicone oil, will significantly affect the degree of bonding between the organosilicon material and the PU resin. This technical solution uses a combination of hydrogenated silicone oil, polyether-modified silicone oil, and epoxy-modified hydrogenated silicone oil, which can significantly improve the bonding strength between the surface modified layer of the organosilicon material and the polyurethane synthetic leather, and ensure the high temperature resistance, acid resistance, and UV resistance of the surface treatment layer.

[0094] (I) The addition of a small amount of polyether-modified silicone oil is very important for improving the adhesion strength between the surface modified layer of the silicone material and the polyurethane synthetic leather. For example, in Comparative Example 1, no polyether-modified silicone oil was added. Although the content of this component in this formula is relatively low, if this component is not added, the PU resin and the silicone component will be easily separated. Especially after ultraviolet irradiation, the folding fastness of the surface modified layer and the polyurethane synthetic leather is not ideal, which decreases from 100,000 times in Example 6 to 80,000 times, a large decrease. In addition, the addition of polyether-modified silicone oil not only increases the ultraviolet radiation resistance of the polyurethane synthetic leather after surface treatment, but also can further improve the appearance, antifouling ability and feel of the surface modified layer of the silicone material. Compared with Example 6, the leather surface after surface treatment in Comparative Example 1 has large flaws (bright stripes), and the appearance grade is reduced from Grade 1 in Example 6 to Grade 3; the antifouling ability of the leather surface after surface treatment in Comparative Example 1 is reduced from Grade 4 in Example 6 to Grade 3, and slight stains appear; the hand feel of the leather surface after surface treatment in Comparative Example 1 is reduced from Grade 1 in Example 6 to Grade 3, and the hand feel is average and not smooth. The addition of a small amount of polyether-modified silicone oil can simultaneously ensure the adhesion performance of the silicone material and the synthetic leather, as well as the hand feel and antifouling ability of the synthetic leather surface, and has dual functions, and has a significant impact on the various properties of the polyurethane synthetic leather after surface treatment, which was not expected by the inventor before research and development. Therefore, a key technical point to achieve the effective combination of silicone material and PU resin is the addition of a small amount of polyether-modified silicone oil.

[0095] (II) Epoxy-modified hydrogenated silicone oil and general hydrogenated silicone oil need to be added to the formula at the same time to ensure the adhesion between the surface treatment layer and the polyurethane synthetic leather, as well as the feel and anti-fouling ability of the synthetic leather surface. For example, in Comparative Example 2, no epoxy-modified hydrogenated silicone oil was used, and all general hydrogenated silicone oils were used. The adhesion between the surface treatment layer and the polyurethane synthetic leather decreased very seriously, and the heat resistance, acid resistance and ultraviolet radiation resistance of the material decreased significantly. The lack of epoxy-modified silicone oil makes the bonding between the silicone component and the polyurethane component poor, so it is easy to de-powder and delaminate in the folding test. In addition, the lack of the addition of epoxy-modified hydrogenated silicone oil will also cause the anti-fouling ability of the product surface to decrease, and slight defects and defect points will appear (compared with Example 6). If epoxy-modified hydrogenated silicone oil is used entirely and general hydrogenated silicone oil is not used, the cross-linking density of the system will be affected due to the steric effect of the side chain epoxy. For example, in Comparative Example 6, the general hydrogen-containing silicone oil is not used, which will lead to incomplete cross-linking and curing of the material, resulting in poor hand feel of the synthetic leather. At the same time, incomplete cross-linking and curing also leads to decreased adhesion at the surface, so the folding test is prone to powdering and delamination. From the data comparison of Comparative Example 2, Comparative Example 6 and Example 6, it can be seen that the use of hydrogen-containing silicone oil is very important for the realization of this technical solution. It is necessary to ensure that general hydrogen-containing silicone oil and epoxy-modified hydrogen-containing silicone oil are present in the formula in a certain proportion. If the hydrogen-containing silicone oil in the formula uses any one of them, although the total amount remains unchanged (the total amount of various silicone oils used in Comparative Example 2, Comparative Example 6 and Example 6 is consistent), it will cause the folding test to be prone to powdering and delamination. However, once the two are mixed and used, the bonding performance and resistance of the product can be greatly improved, and the product appearance, feel and anti-fouling ability can be improved at the same time.

[0096] Secondly, the type and addition method of the solvent will also have a significant impact on the adhesion firmness between the surface modification layer of the silicone material and the polyurethane synthetic leather. For example, only Class A solvent was used in Comparative Example 3, resulting in a decrease in the adhesion between the surface modification layer of the silicone material and the polyurethane synthetic leather, and a decrease in the ability to resist ultraviolet radiation (a decrease of 15,000 times compared with Example 6). In addition, if only Class A solvent is used, the anti-fouling ability of the product surface will be seriously reduced, from level 4 in Example 6 to level 2; resulting in more defects on the surface of the product and a worse feel. For another example, although Class A solvent and Class B solvent were used at the same time in Comparative Example 5, they were not mixed with hydroxyl-terminated polydimethylsiloxane and PU resin respectively, resulting in a decrease in the adhesion between the surface modification layer of the silicone material and the polyurethane synthetic leather, and a decrease in the ability to resist ultraviolet radiation (a decrease of 10,000 times compared with Example 6). At the same time, relative to Example 6, the product surface of Comparative Example 5 has larger defects (bright stripes), unsatisfactory anti-fouling ability (level 3), and a decreased feel (level 2). This shows that the key technical point of using silicone materials and PU resins together lies in the selection of solvents in the formula (both Class A solvents and Class B solvents need to be selected at the same time), and the process sequence of the two solvents will also have a significant impact on the formation of the finished product. The inventor analyzed that the possible reason is that Class A solvents have better compatibility with silicone materials, and Class B solvents have better compatibility with PU resins. By using them together, the stability of the surface treatment agent of this scheme can be improved. In addition, the use of appropriate solvent types and appropriate preparation processes will affect the dispersion effect of the surface treatment agent, as well as the adhesion performance between the surface treatment agent and polyurethane synthetic leather, as well as the appearance, anti-fouling performance and feel.

[0097] Table 2: Polyurethane synthetic leather performance test results

[0098]

[0099]

[0100] The above is only an embodiment of the present invention, and the common knowledge such as the known specific technical solutions and / or characteristics in the solution is not described in detail here. It should be pointed out that for those skilled in the art, without departing from the technical solution of the present invention, several modifications and improvements can be made, which should also be regarded as the protection scope of the present invention, and these will not affect the effect of the implementation of the present invention and the practicality of the patent. The scope of protection required by this application shall be based on the content of its claims, and the specific implementation methods and other records in the specification can be used to interpret the content of the claims.

Claims

1. A leather surface treatment agent, characterized in that: The raw materials are as follows: 100 parts by weight of hydroxyl-terminated polydimethylsiloxane, 10-40 parts of hydrogen-containing silicone oil, 0.2-2 parts of polyether-modified silicone oil, 3-20 parts of epoxy-modified hydrogen-containing silicone oil, 10-50 parts of matting powder, 10-50 parts of PU resin, 200-800 parts of mixed solvent, 1-10 parts of coupling agent, and 0.2-5 parts of catalyst; The hydroxyl content of the hydroxyl-terminated polydimethylsiloxane is 0.03-0.3wt% and the viscosity is 2000-1000000 mPa•s; The epoxy-modified hydrogenated silicone oil has a hydrogen content of 0.2-1.0 wt %, an epoxy group content of 3-14 wt %, and a viscosity of 100-5000 mPa•s; The mixed solvent is composed of a Class A solvent and a Class B solvent; the Class A solvent includes at least one of petroleum ether, white spirit and isoparaffin; the Class B solvent includes at least one of acetone, methyl acetate, ethyl acetate and butyl acetate; The leather surface treatment agent is prepared by the following method: S1: mixing hydroxyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, polyether-modified silicone oil, epoxy-modified hydrogen-containing silicone oil, matting powder, and type A solvent to obtain system I; S2: Mix the PU resin and the type B solvent, and then add them to the system I to obtain the system II; S3: Add a coupling agent and a catalyst to system II to obtain a leather surface treatment agent.

2. A leather surface treatment agent according to claim 1, characterized in that: The hydrogen-containing silicone oil is a side-chain hydrogen-containing silicone oil with a viscosity of 30-500 mPa•s and a hydrogen content of 0.3-1.2 wt %.

3. A leather surface treatment agent according to claim 1, characterized in that: The viscosity of the polyether-modified silicone oil is 30-200 mPa•s, and its structural formula is shown in formula (1); Formula (1) Wherein, m+n is an integer of 10-50, and n / (m+n) is 50-100%; a+b is an integer of 8-30.

4. A leather surface treatment agent according to claim 1, characterized in that: The coupling agent includes at least one of KH-540, KH-550, KH-560, KH-570 and KH-792; and the catalyst is chelated tin.

5. A method for preparing a leather surface treatment agent according to any one of claims 1 to 4, characterized in that: The method includes the following steps in sequence: S1: mixing hydroxyl-terminated polydimethylsiloxane, hydrogen-containing silicone oil, polyether-modified silicone oil, epoxy-modified hydrogen-containing silicone oil, matting powder, and type A solvent to obtain system I; S2: Mix the PU resin and the type B solvent, and then add them to the system I to obtain the system II; S3: Add a coupling agent and a catalyst to system II to obtain a leather surface treatment agent.

6. A method for applying a leather surface treatment agent according to any one of claims 1 to 4, characterized in that: The leather surface treatment agent is coated on the surface of the polyurethane synthetic leather, and then baked at 130-170° C. for 3-5 minutes to obtain the surface-treated polyurethane synthetic leather.

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