A water-based treatment agent for leather, its preparation method and application

Abstract

This invention belongs to the technical field of leather treatment agents, and discloses a water-based leather treatment agent, its preparation method, and its application. The water-based leather treatment agent, by weight, comprises: 90-110 parts of waterborne polyurethane resin, 0.5-1 parts of silica powder, 0.5-1 parts of silicon carbide micropowder with a particle size of 20-30 nm, 3-11 parts of additives, and 30-50 parts of deionized water. The silica powder is obtained by surface etching of silica raw material with a particle size of 150-200 nm. The surface etching method involves immersing the silica raw material in an etching solution containing HF and NH4F at 10°C for 5-8 minutes. The concentration of HF in the etching solution is 3-4 wt%, and the concentration of NH4F is 12-14 wt%. This invention discloses a water-based leather treatment agent that combines silica powder obtained through surface etching with silicon carbide micropowder of a specific particle size, achieving excellent matting effects with a relatively low amount of matting powder added.

Description

Technical Field

[0001] This invention relates to the field of leather treatment agents, specifically to a water-based leather treatment agent, its preparation method, and its application. Background Technology

[0002] Matte finish items are ubiquitous in our daily lives. Most household furniture is matte, and the facades of high-rise buildings are also made matte to avoid the dangers of strong reflected light. Some high-end leather bags also have a matte finish to reflect their luxury. In addition, matte paint can effectively cover up imperfections such as scratches, minor dents, or dirt on certain substrates.

[0003] With the rapid development of new energy vehicles in China, the competition in the new energy vehicle market has become fierce. As an important selling point of new energy vehicles, leather used in car interiors has become a product that is developing towards high-end and premium products. Therefore, water-based treatment agents for leather with matte finish have become a hot research topic.

[0004] Currently, people generally use two methods to achieve matte finish on objects: physical and chemical. Post-treatment of the surface and direct addition of matting agents are common physical matting methods. Post-treatment usually refers to roughening the originally smooth paint film surface through simple and crude methods such as chemical etching or mechanical polishing, thereby achieving matte finish. Adding matting agents, on the other hand, involves adding matting particles during the curing process, which directly affects the roughness of the paint film surface, weakens the intensity of reflected light, and ultimately makes the paint film surface matte. Generally speaking, apart from physical matting, all methods that can achieve matte finish on object surfaces can be classified as chemical matting. Specific methods include utilizing the resin's own structure and properties, such as the different curing temperatures of two resins, the compatibility between different phases in the structure, and the insertion of light-absorbing groups into the structure.

[0005] Physical matting agents are generally used for physical matting. The amount of matting agent used is about 3-5% to achieve a good matting effect. However, if too much matting agent such as silica is used, the resin formed after curing will be hard and brittle, reducing its softness and thus reducing the comfort of automotive leather, which does not meet the performance requirements of high-end automotive leather.

[0006] Prior art 1: Chinese patent application 201711370026.5 discloses a method for preparing a water-based matting agent for automotive leather, comprising: (a) preparing raw materials for use, wherein the composition of the reaction raw materials by weight is: 30-50 parts of water-based polyurethane resin, 5-20 parts of self-matting resin, 1-3 parts of leveling agent, 1-5 parts of wax emulsion, 1-5 parts of hand feel agent, 1-5 parts of silica matting powder, 1-3 parts of thickener, and 30-50 parts of deionized water; (b) mixing the water-based polyurethane resin with... (c) Add matting resin to the reactor, heat to 60-90℃ at 50-80 rpm, and hold for 10-50 min; (d) Add silica matting powder, increase the speed to 85-100 rpm, and stir for 10-50 min; (e) Add leveling agent, wax emulsion, hand feel agent and thickener, increase the speed to 105-120 rpm, and stir for 10-50 min; (f) Add deionized water, stir for 20-40 min, cool and discharge to obtain water-based matting agent for PVC automotive leather.

[0007] Existing technology 1 uses a combination of physical and chemical matting to achieve excellent matting effect. However, according to the embodiments of existing technology 1, after the treatment agent is cured, the amount of silica matting powder used is more than 2.4%. In other words, although the matting resin effectively reduces the amount of silica used, the reduction is not high and is insufficient to solve the problem of excessive brittleness of the cured water-based resin. Summary of the Invention

[0008] One of the objectives of this invention is to provide a water-based treatment agent for leather, which, through the combination of silica powder and silicon carbide micro powder after surface etching, can effectively improve the matting performance of the water-based treatment agent for leather with low filler dosage, and avoid the problem that the cured treatment agent is too brittle and unsuitable for high-end automotive leather.

[0009] Another objective of this invention is to provide a water-based leather treatment agent, which, after curing, exhibits excellent matting properties, requires less filler, and provides a good hand feel.

[0010] Meanwhile, the present invention also provides a water-based treatment agent for leather, which, when applied to high-end automotive leather, can provide excellent matting properties, superior hand feel and comfort, and has a high market application prospect.

[0011] To achieve the above objectives, the present invention provides a water-based treatment agent for leather, comprising, by weight: 90-110 parts water-based polyurethane resin, 0.5-1 parts silica powder, 0.5-1 parts silicon carbide micro powder with a particle size of 20-30 nm, 3-11 parts additives, and 30-50 parts deionized water.

[0012] The silica powder is obtained by surface etching of silica raw material with a particle size of 150-200nm. The surface etching method is as follows: the silica raw material is immersed in an etching solution containing HF and NH4F at 10℃ for 5-8 minutes. The concentration of HF in the etching solution is 3-4wt%, and the concentration of NH4F is 12-14wt%.

[0013] The purpose of using matting particles is to increase the surface roughness of the cured resin film, forming a microscopically uneven surface that forces light to undergo continuous refraction, thus reducing the intensity of reflected light and achieving matting. Therefore, forming a rough and highly uneven resin film on the surface is a technical challenge. This invention increases the surface roughness of silica powder by surface etching of silica raw materials. Furthermore, it controls the surface etching morphology of silica raw materials using etching solutions with specific HF and NH4F concentrations, resulting in silica powder with multiple pits on its surface. Some of these pits can combine with silicon carbide microparticles with a particle size of 20-30 nm, achieving a certain effect in the cured resin film:

[0014] Most of the silica powder and silicon carbide micro powder disperse in the resin film to form a surface with high roughness, thereby reducing the intensity of reflected light. A small portion of the silica powder and silicon carbide micro powder combine to form another type of rough surface particles, which disperse in the resin film and change the reflection and refraction angles of the resin film, thus significantly improving the matting performance of water-based leather treatment agents.

[0015] Importantly, since the morphology formed by the etching solution on the surface is highly correlated with the particle size of the silica raw material, after multiple experiments, it was found that by screening silica raw materials with a particle size of 150-200nm and using the etching solution of the present invention, the surface morphology of the final silica powder can be controlled, thereby enabling some silica powder to combine with silicon carbide micro powder.

[0016] To further control the dispersion and bonding ratio of silica powder and silicon carbide micro powder, preferably, the particle size D50 of the silicon carbide micro powder is 23-24 nm; preferably, the particle size D50 of the silica powder is 170-180 nm.

[0017] It should be noted that the particle size range of silica raw materials and silicon carbide micro powder, as well as the particle size D50 of silica powder and silicon carbide micro powder, can be obtained through existing technologies such as sieve screening, and will not be discussed further here.

[0018] Furthermore, the additives include at least one of thickeners, matting agents, defoamers, leveling agents, and plasticizers.

[0019] As a more preferred technical solution, the water-based leather treatment agent of the present invention comprises, by weight parts: 90-110 parts of water-based polyurethane resin, 0.5-1 parts of silica powder, 0.5-1 parts of silicon carbide micro powder with a particle size of 20-30 nm, 1-3 parts of leveling agent, 1-3 parts of defoamer, 0.5-2 parts of thickener, and 30-50 parts of deionized water.

[0020] It should be noted that the matting performance of the technical solution of the present invention is mainly reflected in the processing and compounding of silica powder and silicon carbide powder. Therefore, the waterborne polyurethane resin of the present invention can achieve the technical solution of the present invention regardless of its type, degree of polymerization, or type.

[0021] This invention also discloses a method for preparing a water-based treatment agent for leather, comprising the following steps:

[0022] Step 1: Add waterborne polyurethane resin to the reactor, stir and heat to 60-90℃, and keep warm for 10-50 minutes;

[0023] Step 2: Grind and disperse the silica powder and silicon carbide micro powder to obtain a mixture;

[0024] Step 3: Add the mixture obtained in Step 2 to the water-based polyurethane resin after the insulation in Step 1 is completed, and stir until homogeneous;

[0025] Step 4: Add the additives and stir well;

[0026] Step 5: Add deionized water and stir well.

[0027] Furthermore, in order to improve the dispersibility of the powder, an appropriate amount of silane coupling agent and deionized water can be added during grinding and dispersion. The specific operation of step 2 is as follows: mix silicon dioxide powder and silicon carbide micro powder, and then add an appropriate amount of silane coupling agent and deionized water to grind and disperse to obtain a mixture.

[0028] Preferably, the amount of the silane coupling agent is 2-5% of the total weight of the silicon dioxide powder and silicon carbide micro powder.

[0029] More preferably, the silane coupling agent may be at least one of KH560, A-151, and KH-570.

[0030] Furthermore, the stirring speed in step 1 is 80-90 rpm; the stirring speed in steps 3 and 4 is 100-110 rpm, and the stirring time is 20-30 min.

[0031] Furthermore, the stirring speed in step 5 is 115-135 rpm and the stirring time is 30-40 min.

[0032] The present invention also discloses an application of the above-mentioned water-based leather treatment agent, wherein the water-based leather treatment agent is applied to automotive leather.

[0033] Beneficial effects

[0034] Compared with the prior art, the present invention has at least the following advantages:

[0035] (1) This invention discloses a water-based treatment agent for leather, which combines silica powder that is surface-corroded by a specific corrosive liquid with silicon carbide micro powder of a specific particle size, and can achieve excellent matting effect with a low amount of matting powder added.

[0036] (2) This invention uses a specific HF concentration and NH4F concentration of etching solution to control the surface corrosion morphology of silica raw material, thereby obtaining silica powder with multiple pits on the surface. Some of the pits generated after surface corrosion by the etching solution can combine with silicon carbide micro powder with a particle size of 20-30nm, so that the dispersed silica powder and silicon carbide micro powder achieve one effect in the cured resin film: most of the silica powder and silicon carbide micro powder disperse in the resin film to form a surface with high roughness, thereby reducing the intensity of reflected light. A small part of the silica powder and silicon carbide micro powder combine to form another type of rough surface particles, which are dispersed in the resin film and change the reflection and refraction angle of the resin film, thus significantly improving the matting performance of water-based treatment agents for leather. Detailed Implementation

[0037] The present invention will be further described below with reference to embodiments, but this does not constitute any limitation on the present invention. Any limited modifications made within the scope of the claims of the present invention are still within the scope of the claims of the present invention.

[0038] To illustrate the technical content of the present invention in detail, the following description is provided in conjunction with the embodiments.

[0039] In the following examples and comparative examples, the waterborne polyurethane resin is a waterborne polyurethane acrylate resin, which is purchased from Hubei Langbowan Biomedical Co., Ltd. as waterborne UV resin DR-W470. Therefore, the following examples and comparative examples also include 2-hydroxy-2-methyl-1-phenyl-1-propanone purchased from Shandong Xinghai Chemical Co., Ltd. as a photoinitiator.

[0040] In the following examples and comparative examples, the leveling agent SN4034 and the defoamer SN-6725 were both purchased from Shanghai Shenzhu Chemical Technology Co., Ltd., and the thickener was purchased from polyurethane thickener PU-40 provided by Qingdao Enze Chemical Co., Ltd.

[0041] It should be noted that the technical solution of the present invention can be achieved using other commercially available raw materials, and is not limited to the raw materials purchased as described above.

[0042] In the following examples and comparative examples, the particle size D50 of the silicon carbide micro powder is 24 nm; the particle size D50 of the silicon dioxide powder is 172 nm.

[0043] The following examples and comparative examples were prepared using the following steps:

[0044] Step 1: Add waterborne polyurethane resin to the reactor, stir at 90 rpm and heat to 70°C, then keep warm for 40 min;

[0045] Step 2: Mix silica powder and / or silicon carbide micro powder, then add an appropriate amount of silane coupling agent and deionized water and grind and disperse to obtain a mixture;

[0046] Step 3: Add the mixture obtained in Step 2 to the water-based polyurethane resin after the heat preservation in Step 1, and stir at 110 rpm until homogeneous;

[0047] Step 4: Add leveling agent SN4034, defoamer SN-6725, hindered amine light thickener, and photoinitiator, and stir evenly at 110 rpm;

[0048] Step 5: Add deionized water and stir well at a speed of 125 rpm for 40 minutes.

[0049] Unless otherwise specified, in the following examples and comparative examples, the parts and percentages refer to parts by weight and weight percentage, respectively.

[0050] Example 1

[0051] A water-based treatment agent for leather comprises 90 parts water-based polyurethane resin, 3 parts photoinitiator, 0.5 parts silica powder, 1 part silicon carbide micro powder with a particle size of 20-30 nm, 1.5 parts leveling agent SN4034, 1 part defoamer SN-6725, 1 part hindered amine light thickener, and 40 parts deionized water.

[0052] The silica powder is obtained by surface etching of silica raw material with a particle size of 150-200nm. The surface etching method is as follows: the silica raw material is immersed in an etching solution containing HF and NH4F at 10℃ for 6 minutes for surface etching treatment; wherein the concentration of HF in the etching solution is 3wt% and the concentration of NH4F is 14wt%.

[0053] Example 2

[0054] A water-based treatment agent for leather comprises 110 parts water-based polyurethane resin, 3 parts photoinitiator, 1 part silica powder, 1 part silicon carbide micro powder with a particle size of 20-30 nm, 1.5 parts leveling agent SN4034, 1 part defoamer SN-6725, 1 part hindered amine light thickener, and 40 parts deionized water.

[0055] The silica powder is obtained by surface etching of silica raw material with a particle size of 150-200nm. The surface etching method is as follows: the silica raw material is immersed in an etching solution containing HF and NH4F at 10℃ for 6 minutes for surface etching treatment; wherein the concentration of HF in the etching solution is 3wt% and the concentration of NH4F is 14wt%.

[0056] Example 3

[0057] It is largely the same as Example 2, except that the concentration of HF in the corrosive solution is 3.5 wt% and the concentration of NH4F is 13 wt%.

[0058] Example 4

[0059] It is largely the same as Example 2, except that the concentration of HF in the corrosive solution is 3 wt% and the concentration of NH4F is 12 wt%.

[0060] Comparative Example 1

[0061] It is largely the same as Example 2, except that the silicon dioxide powder is a silicon dioxide raw material with a size of 150-200nm and is not subjected to surface etching treatment.

[0062] Comparative Example 2

[0063] The process is largely the same as in Example 2, except that the silica powder is obtained by surface etching of silica raw material with a particle size of 250-300 nm. The surface etching method is as follows: the silica raw material is immersed in an etching solution containing HF and NH4F at 10°C for 6 min for surface etching treatment; wherein the concentration of HF in the etching solution is 3 wt% and the concentration of NH4F is 14 wt%.

[0064] Comparative Example 3

[0065] The process is largely the same as in Example 2, except that the silica powder is obtained by surface etching of silica raw material with a particle size of 50-80 nm. The surface etching method is as follows: the silica raw material is immersed in an etching solution containing HF and NH4F at 10°C for 6 min for surface etching treatment; wherein the concentration of HF in the etching solution is 3 wt% and the concentration of NH4F is 14 wt%.

[0066] Comparative Example 4

[0067] It is largely the same as Example 2, except that the particle size of the silicon carbide micro powder is 40-50 nm.

[0068] Comparative Example 5

[0069] It is largely the same as Example 2, except that the particle size of the silicon carbide micro powder is 10-15 nm.

[0070] Comparative Example 6

[0071] It is largely the same as Example 2, except that the concentration of HF in the corrosive solution is 3 wt% and the concentration of NH4F is 16 wt%.

[0072] Comparative Example 7

[0073] It is largely the same as Example 2, except that the concentration of HF in the corrosive solution is 3 wt% and the concentration of NH4F is 8 wt%.

[0074] Comparative Example 8

[0075] It is largely the same as Example 2, except that the concentration of HF in the corrosive solution is 6 wt% and the concentration of NH4F is 14 wt%.

[0076] Comparative Example 9

[0077] It is largely the same as Example 2, except that the concentration of HF in the corrosive solution is 1 wt% and the concentration of NH4F is 14 wt%.

[0078] Performance testing

[0079] Matteness test: The cured Examples 1-4 and Comparative Examples 1-9 were tested using a 60-degree gloss meter, and the results are shown in Table 1.

[0080] Table 1. Extinction performance results of Examples 1-4 and Comparative Examples 1-9

[0081]

[0082]

[0083] According to the results in Table 1:

[0084] According to the data from Examples 1-4, the present invention uses silica powder and silicon carbide micro powder that have undergone surface etching treatment with a specific etching solution. With a total matte powder content of less than 2%, it can achieve a relative gloss of less than 20%, reaching the matte level, and the matte performance is significant. Among them, the etching solution used in Example 3 can maximize the improvement effect of matte performance by etching the silica raw material.

[0085] The matting performance of cured leather treatment agents is based on the microscopic unevenness of the surface, which affects the way light is reflected on the leather surface, thereby reducing the gloss. The addition of matting powders such as silica and silicon carbide is to increase the surface unevenness, thereby affecting the reflection of light. This invention uses a combination of silica powder and silicon carbide micro powder that have been surface-etched with a specific etching solution. On the one hand, most of the silica and silicon carbide micro powder are dispersed and evenly distributed on the cured leather treatment agent to form a microscopically uneven surface, thus achieving a basic matting effect. On the other hand, the pits of the etched silica combine with some silicon carbide micro powder of a specific particle size to form particles with different morphologies, thereby changing the microscopic unevenness of some parts of the cured leather treatment agent. This, together with most of the silica and silicon carbide micro powder, has a synergistic effect on light reflection, significantly improving the matting performance of the leather treatment agent.

[0086] According to the data comparison between Example 2 and Comparative Example 1, it can be seen that the combination of silica powder without surface etching treatment and silicon carbide micro powder produces a simple matte effect. The relative gloss of Comparative Example 1 is significantly improved, exceeding 20%, and is only at the semi-matte level.

[0087] A comparison of the data from Examples 2 and Comparative Examples 2-5 shows that the selection of the particle size range of silica raw materials and silicon carbide micro powder also has a significant impact on the technical solution of this invention. Comparative Example 2 uses silica raw materials with excessively large particle sizes, resulting in significant changes in the surface morphology of silica after surface etching, producing numerous or large pits. This leads to a substantial increase in the proportion of small-particle-size silicon carbide micro powder combined with silica, causing most of the silica and silicon carbide micro powder to agglomerate instead of being dispersed on the surface of the cured leather treatment agent, resulting in a significant decrease in its matting performance compared to Comparative Example 1. In contrast, Comparative Examples 3 and 4 show a significant improvement in relative gloss because the surface pits of the silica powder after surface etching do not allow for good bonding with the silicon carbide micro powder, thus reducing the bonding ratio between silica powder and silicon carbide micro powder. Comparative Example 5 uses silicon carbide micro powder with an excessively small particle size range, causing most of the silicon carbide micro powder to agglomerate with the silica powder, resulting in a significant decrease in its matting performance compared to Comparative Example 1.

[0088] According to the data comparison of Example 2 and Comparative Examples 6-9, the concentrations of HF and NH4F in the etching solution have a significant impact on the matting performance of the leather treatment agent of the present invention. The reason is that unsuitable concentrations of HF and NH4F will lead to differences in the surface etching effect of silica raw materials, thereby affecting the surface morphology of silica powder.

[0089] The embodiments presented herein are merely selected implementations based on combinations of all possible embodiments. The appended claims should not be limited to the embodiments described herein. Some numerical ranges used in the claims include sub-ranges within them, and variations within these ranges should also be covered by the appended claims.

Claims

1. A water-based treatment agent for leather, characterized in that, By weight, it includes: 90-110 parts waterborne polyurethane resin, 0.5-1 parts silica powder, 0.5-1 parts silicon carbide micro powder with a particle size of 20-30nm, 3-11 parts additives, and 30-50 parts deionized water. The silica powder is obtained by surface etching of silica raw material with a particle size of 150-200nm. The surface etching method is as follows: the silica raw material is immersed in an etching solution containing HF and NH4F at 10℃ for 5-8 minutes. The concentration of HF in the etching solution is 3-4wt%, and the concentration of NH4F is 12-14wt%.

2. The water-based leather treatment agent according to claim 1, characterized in that, The particle size D50 of the silicon carbide micro powder is 23-24 nm.

3. The water-based leather treatment agent according to claim 1, characterized in that, The particle size D50 of the silica powder is 170-180 nm.

4. The water-based leather treatment agent according to claim 1, characterized in that, The additives include at least one of thickener, matting agent, defoamer, leveling agent, and plasticizer.

5. A method for preparing a water-based leather treatment agent as described in any one of claims 1-4, characterized in that, Includes the following steps: Step 1: Add waterborne polyurethane resin to the reactor, stir and heat to 60-90℃, and keep warm for 10-50 minutes; Step 2: Grind and disperse the silica powder and silicon carbide micro powder to obtain a mixture; Step 3: Add the mixture obtained in Step 2 to the water-based polyurethane resin after the insulation in Step 1 is completed, and stir until homogeneous; Step 4: Add the additives and stir well; Step 5: Add deionized water and stir well.

6. The method for preparing the water-based leather treatment agent according to claim 5, characterized in that, The specific operation of step 2 is as follows: mix silicon dioxide powder and silicon carbide micro powder, then add an appropriate amount of silane coupling agent and deionized water to grind and disperse to obtain a mixture.

7. The method for preparing the water-based leather treatment agent according to claim 5, characterized in that, The stirring speed in step 1 is 80-90 rpm; the stirring speed in steps 3 and 4 is 100-110 rpm, and the stirring time is 20-30 min.

8. The method for preparing the water-based leather treatment agent according to claim 5, characterized in that, The stirring speed in step 5 is 115-135 rpm and the stirring time is 30-40 min.

9. The application of the water-based leather treatment agent as described in any one of claims 1-4, characterized in that, The water-based leather treatment agent is applied to automotive leather.

Images