Water-based treatment agent for leather as well as preparation method and application of water-based treatment agent

Abstract

The invention belongs to the technical field of treatment agents for leather, and discloses a water-based treatment agent for leather as well as a preparation method and application thereof.The water-based treatment agent for leather is prepared from the following components in parts by weight: 90-110 parts of water-based polyurethane resin, 0.5-1 part of silicon dioxide powder, 0.5-1 part of silicon carbide micro powder with the particle size of 20-30 nm, 3-11 parts of auxiliaries and 30-50 parts of deionized water; wherein the silicon dioxide powder is obtained by carrying out surface corrosion on a silicon dioxide raw material with the particle size of 150-200nm, and the surface corrosion method comprises the following steps: soaking the silicon dioxide raw material in a corrosive liquid containing HF and NH4F at 10 DEG C, and carrying out surface corrosion treatment for 5-8 minutes; wherein the concentration of HF in the corrosive liquid is 3-4 wt%, and the concentration of NH4F is 12-14 wt%. The invention discloses a water-based treatment agent for leather, which is characterized in that silicon dioxide powder subjected to surface corrosion through a specific corrosive liquid is compounded with silicon carbide micro powder with a specific particle size, and an excellent matting effect can be realized under the condition of a relatively low matting powder addition amount.

Description

Technical Field

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

[0002] Matte items can be found everywhere in our daily lives. Most of the home furniture is matte. The facades of high-rise buildings are also made with a matte effect to avoid the dangers of reflected strong light. Some high-end leather bags also have a matte surface to reflect their high-end nature. In addition, if some substrates are scratched, slightly dented or dirty, matte paint can cover these defects very well.

[0003] With the rapid development of new energy vehicles in China, the competition in new energy vehicles has entered a fierce state. As an important selling point of new energy vehicles, leather used for car interior has become a high-end and advanced product. Therefore, water-based leather treatment agents with matte effect have become a research and development hotspot.

[0004] At present, people generally use physical and chemical methods to make objects matte. Surface post-treatment and direct addition of matting agents are commonly used physical matting methods. Surface post-treatment usually refers to making the originally flat surface of the paint film rough and matte through simple and crude methods such as chemical etching or mechanical polishing, while the addition of matting agents is during the curing process. The addition of matting particles directly affects the roughness of the paint film surface, weakens the intensity of reflected light, and finally makes the paint film surface matte; generally speaking, in addition to physical matting, all means of making the surface of an object matte can be classified as chemical matting. The specific content includes the use of the structure and properties of the resin itself, such as the different curing temperatures of two resins, the compatibility between the phases in the structure, and the insertion of groups with light-absorbing properties into the structure.

[0005] Generally, matting agents are used for physical matting. The dosage of matting agent is about 3-5% to achieve a good matting effect. However, excessive use of matting agent such as silica will cause the resin formed after curing to be hard and brittle, reducing its softness, and reducing the comfort of the automotive leather. It 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 PVC automotive leather matting agent, comprising: (a) preparing raw materials for use, wherein the reaction raw materials are composed of 30 to 50 parts of water-based polyurethane resin, 5 to 20 parts of self-matting resin, 1 to 3 parts of leveling agent, 1 to 5 parts of wax emulsion, 1 to 5 parts of hand feeling agent, 1 to 5 parts of silica matting powder, 1 to 3 parts of thickener, and 30 to 50 parts of deionized water; (b) mixing water-based polyurethane resin, self-matting resin, Add matting resin into the reaction kettle, raise the temperature to 60-90°C at a speed of 50-80 rpm, and keep warm for 10-50 min; (c) add silica matting powder, increase the speed to 85-100 rpm, and stir for 10-50 min; (d) add leveling agent, wax emulsion, hand feeling agent and thickener, increase the speed to 105-120 rpm, and stir for 10-50 min; (e) add deionized water, stir for 20-40 min, cool and discharge to obtain water-based PVC automotive leather matting agent.

[0007] Prior art 1 combines physical matting and chemical matting to achieve excellent matting effect. However, according to the embodiment of prior art 1, after the treatment agent is cured, the amount of silica matting powder used is more than 2.4%. That is to say, although the matting resin effectively reduces the amount of silica used, the reduction is not high and is not enough to solve the problem of excessive brittleness of the cured water-based resin. Summary of the invention

[0008] One of the purposes of the present invention is to provide an aqueous leather treatment agent, which can effectively improve the matting performance of the aqueous leather treatment agent under low filler dosage by combining surface-corroded silica powder and silicon carbide micropowder, thereby avoiding the problem that the cured treatment agent is too brittle and unsuitable for high-end automotive leather.

[0009] Another object of the present invention is to provide an aqueous leather treatment agent, wherein the prepared aqueous leather treatment agent has excellent matting performance after curing, has a small amount of filler, and has a good hand feel.

[0010] At the same time, the present invention also provides an aqueous leather treatment agent, which, when applied to high-end automotive leather, can provide the automotive leather with excellent matting performance, excellent hand feel and comfort, and has a very high market application prospect.

[0011] To achieve the above object, the present invention provides an aqueous leather treatment agent, which comprises, by weight: 90-110 parts of aqueous polyurethane resin, 0.5-1 parts of silicon dioxide powder, 0.5-1 parts of silicon carbide micropowder with a particle size of 20-30 nm, 3-11 parts of auxiliary agents, and 30-50 parts of deionized water;

[0012] The silicon dioxide powder is obtained by surface corrosion of silicon dioxide raw material with a particle size of 150-200nm. The surface corrosion method is: immersing the silicon dioxide raw material in a 10°C corrosion solution containing HF and NH4F for surface corrosion treatment for 5-8 minutes; wherein the concentration of HF in the corrosion solution is 3-4wt%, and the concentration of NH4F is 12-14wt%.

[0013] Since the matte particles are used to increase the roughness of the surface of the cured resin film, a layer of uneven surface is formed at the microscopic level so that the light needs to be refracted continuously to reduce the intensity of the reflected light, thereby achieving the purpose of matte; therefore, how to form a rough and highly uneven resin film on the surface is a technical problem; the present invention increases the surface roughness of the silicon dioxide powder by surface etching the silicon dioxide raw material, and even controls the surface corrosion morphology of the silicon dioxide raw material by etching liquid with specific HF concentration and NH4F concentration, thereby obtaining a silicon dioxide powder with a plurality of pits on the surface morphology, and the pits generated by the etching liquid after the surface etching can be partially combined with the silicon carbide micropowder with a particle size of 20-30nm, so that the dispersed silicon dioxide powder and the silicon carbide micropowder achieve an effect in the cured resin film:

[0014] Most of the silica powder and silicon carbide powder are dispersed in the resin film to form a surface with higher roughness, thereby reducing the intensity of reflected light. A small part of the silica powder is combined with the silicon carbide powder to form another form of rough surface particles, which are dispersed in the resin film and change the reflection and refraction angles of the resin film, thereby greatly improving the matte performance of the water-based leather treatment agent as a whole.

[0015] Importantly, since the morphology formed by the surface corrosion of the etching liquid is also highly correlated with the particle size of the silicon dioxide raw material, it was found through multiple experiments that screening out silicon dioxide raw materials with a particle size of 150-200nm and using the etching liquid of the present invention can control the surface morphology of the final silicon dioxide powder, thereby allowing part of the silicon dioxide powder to be combined with silicon carbide micropowder.

[0016] In order to further control the dispersion ratio and combination ratio of silicon dioxide powder and silicon carbide micropowder, preferably, the particle size D50 of the silicon carbide micropowder is 23-24 nm; preferably, the particle size D50 of the silicon dioxide powder is 170-180 nm.

[0017] It should be noted that the particle size range of silicon dioxide raw materials and silicon carbide micropowder and the particle size D50 screening of silicon dioxide powder and silicon carbide micropowder can be obtained by existing technologies such as sieve screening, and will not be explained in detail here.

[0018] Furthermore, the auxiliary agent includes at least one of a thickener, a matting agent, a defoaming agent, a leveling agent, and a plasticizer.

[0019] As a more preferred technical solution, the aqueous leather treatment agent of the present invention comprises, by weight: 90-110 parts of aqueous polyurethane resin, 0.5-1 parts of silicon dioxide powder, 0.5-1 parts of silicon carbide micropowder with a particle size of 20-30 nm, 1-3 parts of leveling agent, 1-3 parts of defoaming agent, 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 silicon dioxide powder and silicon carbide powder. Therefore, the water-based polyurethane resin of the present invention, regardless of its type or type and degree of polymerization, can realize the technical solution of the present invention.

[0021] The present invention also discloses a method for preparing an aqueous leather treating agent, comprising the following steps:

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

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

[0024] Step 3: Add the mixture obtained in step 2 to the water-based polyurethane resin after the heat preservation in step 1, and stir evenly;

[0025] Step 4: Add additives and stir evenly;

[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: mixing the silicon dioxide powder and the silicon carbide powder, and then adding an appropriate amount of silane coupling agent and deionized water for grinding and dispersion to obtain a mixture.

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

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

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

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

[0032] The invention also discloses an application of the aqueous leather treatment agent, wherein the aqueous 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) The present invention discloses an aqueous leather treatment agent, which is a compound of silicon dioxide powder that is surface-etched by a specific etching liquid and silicon carbide micropowder of a specific particle size, and can achieve an excellent matte effect with a relatively low amount of matte powder added;

[0036] (2) The present invention uses an etching solution with a specific HF concentration and NH4F concentration to control the surface corrosion morphology of the silicon dioxide raw material, thereby obtaining a silicon dioxide powder with a plurality of pits on the surface. Some of the pits generated after the surface is corroded by the etching solution can be combined with silicon carbide micropowder with a particle size of 20-30nm, so that the dispersed silicon dioxide powder and silicon carbide micropowder achieve an effect in the cured resin film: most of the silicon dioxide powder and silicon carbide micropowder are dispersed in the resin film to form a surface with a higher roughness, thereby weakening the intensity of the reflected light, and a small part of the silicon dioxide powder is combined with the silicon carbide micropowder to form another form of rough surface particles, which are dispersed in the resin film to change the reflection and refraction angles of the resin film, thereby greatly improving the matte performance of the aqueous leather treatment agent as a whole. DETAILED DESCRIPTION

[0037] The present invention will be further described below in conjunction with the embodiments, but it does not constitute any limitation to the present invention. Any limited number of 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] In order to explain the technical content of the present invention in detail, further description is given below in conjunction with the implementation modes.

[0039] In the following examples and comparative examples, the waterborne polyurethane resin is a waterborne polyurethane acrylate resin, which is purchased from the waterborne UV resin DR-W470 provided by Hubei Langbowan Biomedicine Co., Ltd. Therefore, the following examples and comparative examples also add 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 defoaming agent SN-6725 were purchased from Shanghai Shenzhu Chemical Technology Co., Ltd., and the thickener was purchased from the 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 implemented by other commercially available raw materials and is not limited to the raw materials purchased above.

[0042] In the following examples and comparative examples, the particle size D50 of the silicon carbide 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 by the following steps:

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

[0045] Step 2: Mix silicon dioxide powder and / or silicon carbide powder, then add appropriate amount of silane coupling agent and deionized water for grinding and dispersion to obtain a mixture;

[0046] Step 3: Add the mixture obtained in step 2 to the water-based polyurethane resin after the insulation in step 1, and stir evenly at a speed of 110 rpm;

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

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

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

[0050] Example 1

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

[0052] The silicon dioxide powder is obtained by surface etching of silicon dioxide raw material with a particle size of 150-200nm, and the surface etching method is: immersing the silicon dioxide raw material in a 10°C etching solution containing HF and NH4F for surface etching for 6 minutes; 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 leather treatment agent includes 110 parts of water-based polyurethane resin, 3 parts of photoinitiator, 1 part of silicon dioxide powder, 1 part of silicon carbide micropowder with a particle size of 20-30 nm, 1.5 parts of leveling agent SN4034, 1 part of defoamer SN-6725, 1 part of hindered amine optical thickener, and 40 parts of deionized water;

[0055] The silicon dioxide powder is obtained by surface etching of silicon dioxide raw material with a particle size of 150-200nm, and the surface etching method is: immersing the silicon dioxide raw material in a 10°C etching solution containing HF and NH4F for surface etching for 6 minutes; wherein the concentration of HF in the etching solution is 3wt%, and the concentration of NH4F is 14wt%.

[0056] Example 3

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

[0058] Example 4

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

[0060] Comparative Example 1

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

[0062] Comparative Example 2

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

[0064] Comparative Example 3

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

[0066] Comparative Example 4

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

[0068] Comparative Example 5

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

[0070] Comparative Example 6

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

[0072] Comparative Example 7

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

[0074] Comparative Example 8

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

[0076] Comparative Example 9

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

[0078] Performance Testing

[0079] Matt test: The cured Examples 1-4 and Comparative Examples 1-9 were tested using a 60-degree gloss meter. 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, we can see that:

[0084] According to the data of Examples 1-4, the present invention adopts a compound of silicon dioxide powder and silicon carbide micropowder that have been treated with surface corrosion by a specific etching liquid. When the total matte powder dosage is less than 2%, a relative glossiness of less than 20% can be achieved, reaching the semi-glossy level, and the matte performance is significant; among them, the etching liquid used in Example 3 can maximize the improvement effect of the matte performance by corroding the silicon dioxide raw material.

[0085] The matting performance of the cured leather treatment agent is based on the microscopic unevenness of the surface, and the effect of reducing the gloss is achieved by affecting the reflection mode of light on the leather surface; and the addition of matting powders such as silicon dioxide and silicon carbide is to increase the surface unevenness, thereby affecting the reflection of light; the present invention adopts a compound of silicon dioxide powder and silicon carbide micropowder that have been treated with surface corrosion by a specific corrosion liquid. On the one hand, most of the silicon dioxide and silicon carbide micropowder are dispersed and evenly distributed on the cured leather treatment agent to form a microscopic uneven surface, thereby achieving a basic matting effect; on the other hand, the pits of the corroded silicon dioxide are combined with some silicon carbide micropowders of a specific particle size to form particles with different morphologies, thereby changing the microscopic uneven state of some positions of the cured leather treatment agent, and producing a synergistic effect of affecting light reflection with most of the silicon dioxide and silicon carbide micropowders, thereby significantly improving the matting performance of the leather treatment agent.

[0086] According to the data comparison between Example 2 and Comparative Example 1, the compounding of silicon dioxide powder without surface corrosion treatment and silicon carbide micropowder produces a simple matte effect superposition. The relative glossiness of Comparative Example 1 is greatly improved, and exceeds 20%, which is only a semi-matt level.

[0087] According to the data comparison between Example 2 and Comparative Examples 2-5, it can be seen that the selection of the particle size range of the silica raw material and the particle size range of the silicon carbide powder also have a relatively important influence on the technical solution of the present invention; Comparative Example 2 uses a silica raw material with an overly large particle size, and the surface morphology of the silica after surface corrosion changes greatly, resulting in more or larger pits, thereby greatly increasing the proportion of small-particle silicon carbide powder combined with silica, resulting in most of the silica and silicon carbide powder agglomeration, and not dispersed on the surface of the leather treatment agent after curing, resulting in its matting performance being significantly reduced compared with Comparative Example 1; while Comparative Examples 3 and Comparative Examples 4 are difficult to combine with silicon carbide powder due to the surface pits of the silica powder after surface corrosion, which reduces the combination ratio of silica powder and silicon carbide powder, resulting in a significant improvement in relative gloss; Comparative Example 5 uses silicon carbide powder with an overly small particle size range, resulting in most of the silicon carbide powder and silica powder agglomeration, resulting in its matting performance being significantly reduced compared with Comparative Example 1.

[0088] According to the data comparison between Example 2 and Comparative Examples 6-9, the concentrations of HF and NH4F in the etching solution will have a great influence 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 corrosion effect of the silica raw material, thereby affecting the surface morphology of the silica powder.

[0089] The embodiments presented herein are only embodiments selected according to the combination of all possible embodiments. The appended claims should not be limited by the embodiments describing the present invention. Some numerical ranges used in the claims include sub-ranges therein, and the changes in these ranges should also be covered by the appended claims.

Claims

1. A water-based leather treatment agent, characterized in that The composition comprises, by weight: 90-110 parts of waterborne polyurethane resin, 0.5-1 parts of silicon dioxide 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 silicon dioxide powder is obtained by surface corrosion of silicon dioxide raw material with a particle size of 150-200nm. The surface corrosion method is: immersing the silicon dioxide raw material in a 10°C corrosion solution containing HF and NH4F for surface corrosion treatment for 5-8 minutes; wherein the concentration of HF in the corrosion solution is 3-4wt%, and the concentration of NH4F is 12-14wt%.

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

3. The aqueous leather treating agent according to claim 1, characterized in that The particle size D50 of the silicon dioxide powder is 170-180 nm.

4. The aqueous leather treating agent according to claim 1, characterized in that The auxiliary agent includes at least one of a thickener, a matting agent, a defoaming agent, a leveling agent, and a plasticizer.

5. A method for preparing an aqueous leather treatment agent as claimed in any one of claims 1 to 4, characterized in that: The steps include: Step 1: Add waterborne polyurethane resin to the reactor, stir and heat to 60-90°C, and keep warm for 10-50 minutes; Step 2: Grind and disperse silicon dioxide powder and silicon carbide powder to obtain a mixture; Step 3: Add the mixture obtained in step 2 to the water-based polyurethane resin after the heat preservation in step 1, and stir evenly; Step 4: Add additives and stir evenly; Step 5: Add deionized water and stir well.

6. The method for preparing an aqueous leather treating agent according to claim 5, characterized in that: The specific operation of step 2 is: mixing silicon dioxide powder and silicon carbide powder, and then adding a proper amount of silane coupling agent and deionized water to grind and disperse to obtain a mixture.

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

8. The method for preparing an aqueous leather treating agent according to claim 5, characterized in that: The stirring speed of step 5 is 115-135 rpm, and the stirring speed is 30-40 min.

9. The use of the aqueous leather treating agent according to any one of claims 1 to 4, characterized in that: The aqueous leather treating agent is applied to automotive leather.

Images