Self-cleaning nanosol coating liquid, preparation method, TPO substrate and application thereof

Abstract

This invention discloses a self-cleaning nano-sol coating solution, comprising, by weight, 25-50 parts of modified nano-Al2O3 polyvinyl alcohol sol, 2-6 parts of organosilicon abrasion resistant agent, 1-3 parts of crosslinking agent, 2-4 parts of silane coupling agent, 1-3 parts of wetting and leveling agent, 3-7 parts of cosolvent, 20-40 parts of deionized water, and 1-3 parts of thickener. Another objective of this invention is to disclose a method for preparing the self-cleaning nano-sol coating solution, comprising the following steps: Step 1, obtaining a modified nano-Al2O3 dispersion; Step 2, mixing the modified nano-Al2O3 dispersion from Step 1 with a polyvinyl alcohol solution, and subjecting it to high-speed shear emulsification and ultrasonic emulsification treatment; Step 3, obtaining a modified nano-Al2O3 polyvinyl alcohol sol; Step 4, sequentially adding the organosilicon abrasion resistant agent, cosolvent, wetting and leveling agent, and defoamer; Step 5, adding the crosslinking agent and thickener; Step 6, allowing the solution to stand to defoam, filtering, and obtaining the self-cleaning nano-sol coating solution. The cleaning nano-sol coating solution of this invention is green and environmentally friendly, and has high transparency.

Description

Technical Field

[0001] This invention relates to the field of surface coatings, and more particularly to a self-cleaning nanosol coating, its preparation method, a TPO substrate, and its applications. Background Technology

[0002] Thermoplastic polyolefin (TPO) materials have become an important basic material in the fields of automotive interiors (such as dashboards, door panels, and seats) and high-end industrial tarpaulins due to their lightweight characteristics, recyclability, chemical resistance, and excellent mechanical properties. They have also gradually developed into high-end categories such as fifth-generation tarpaulin products and new TPO leather.

[0003] However, TPO substrates themselves have low surface energy, weak polarity, and strong inertness, resulting in poor adhesion to functional surface coatings. Direct application leads to easy contamination, scratches, and insufficient aesthetics and durability. Currently, there is a lack of surface treatment coatings specifically developed for TPO materials. The industry typically uses coatings designed for polyvinyl chloride (PVC) or thermoplastic polyurethane (TPU), which have serious inapplicability and drawbacks, as follows: 1) Ordinary transparent coatings have difficulty balancing hardness and flexibility. High hardness makes them prone to cracking when bent, while good flexibility results in low hardness and poor wear resistance. 2) Although silicone coatings are wear-resistant, their lack of transparency affects the appearance of the product; 3) Existing coatings cannot simultaneously integrate multiple functions such as self-cleaning and antibacterial properties.

[0004] The development of functional surface coating technology is primarily driven by three industry demands: 1. Multifunctional Integration Requirements: New TPO materials need to meet multiple functional requirements simultaneously, such as: 1) In terms of physical properties, TPO materials require practical characteristics such as high scratch resistance, high wear resistance, and chemical corrosion resistance. 2) In terms of hygiene, it needs to be easy to clean, antibacterial and mildew-proof, especially for high-contact areas of automotive interior leather and high-humidity outdoor environments in agricultural greenhouses; 3) Visually and tactilely, it is required to maintain the surface effect of the underlying TPO material itself, such as having a leather-like texture and high transparency, among other high-end properties; 4) In terms of processing performance, it must be able to adapt to various stretching process requirements to avoid coating cracking during processing.

[0005] 2. Expanded substrate compatibility: TPO materials are often used in combination with polypropylene foam layers, fabric layers, etc. The surface coating must ensure a strong bond with the multi-layer structure while maintaining low VOC and low odor characteristics.

[0006] 3. Environmental Regulations Drive the Transformation of Waterborne Technologies: While traditional solvent-based coatings offer excellent film-forming properties and substrate adhesion, they contain large amounts of volatile organic compounds (VOCs), which continuously release harmful substances in enclosed environments such as automotive interiors and agricultural greenhouses. With increasingly stringent global environmental regulations (such as Chinese national standards and the EU REACH regulation), the market demands a shift towards waterborne coating systems. However, early waterborne coatings suffered from uneven gloss and decreased adhesion during stretch molding, failing to meet the high-quality requirements of applications such as automotive interiors and transparent greenhouses.

[0007] These demands have collectively driven the evolution of functional surface coating technologies for TPO substrates from single-solvent systems towards environmentally friendly, multifunctional, and highly compatible approaches. Developing a specialized coating that can firmly bond with TPO substrates while simultaneously achieving multiple superior properties such as high transparency, high abrasion resistance, scratch resistance, flexibility, long-lasting self-cleaning, antibacterial properties, and weather resistance has become a critical technological bottleneck for promoting high-end TPO applications. Therefore, a new technical solution is urgently needed to address at least one of these technical problems. Summary of the Invention

[0008] One objective of this invention is to provide a self-cleaning nano-sol coating and its preparation method. The prepared self-cleaning nano-sol coating is environmentally friendly, highly transparent, and exhibits good adhesion to TPO substrates. Another objective of this invention is to provide a TPO substrate with good wear resistance, a surface capable of long-term self-cleaning, and the ability to inhibit microbial growth.

[0009] To achieve the above-mentioned technical objectives and requirements, the technical solution adopted by the present invention is: a self-cleaning nano-sol coating liquid, characterized in that, by weight, it comprises 25-50 parts of modified nano-Al2O3 polyvinyl alcohol sol, 2-6 parts of organosilicon wear-resistant agent, 1-3 parts of crosslinking agent, 1-3 parts of wetting and leveling agent, 3-7 parts of cosolvent, 20-40 parts of deionized water, and 1-3 parts of thickener.

[0010] As a preferred technical solution, the modified nano-Al2O3 polyvinyl alcohol sol has a nano-Al2O3 particle size of 10-50 nm and a degree of alcoholysis of 88-99% for polyvinyl alcohol.

[0011] As a preferred technical solution, the organosilicon wear-resistant agent is a hydroxyl-terminated or amino-modified organopolysiloxane emulsion.

[0012] As a preferred technical solution, the crosslinking agent is one of aziridine crosslinking agents, carbodiimide crosslinking agents, or blocked isocyanate crosslinking agents.

[0013] As a preferred technical solution, the co-solvent is propylene glycol methyl ether.

[0014] This invention also provides a method for preparing a self-cleaning nano-sol coating, characterized by comprising the following steps: Step 1: In a jacketed high-speed shear dispersion emulsification reactor, first prepare an 18-22% nitric acid solution, and slowly add nano-Al2O3 powder at a weight ratio of 1:(4-6). Circulate hot water through the jacket and add silane coupling agent at 55-60℃. Emulsify at a high-speed shear rate of 1400-1600 r / min for 1.5-2.5 hours. After filtration, obtain the modified nano-Al2O3 dispersion. Step 2: Mix the modified nano-Al2O3 dispersion from Step 1 with the polyvinyl alcohol solution, and subject it to high-speed shear emulsification and ultrasonic emulsification at 55-60℃ for 2.5-3 hours of forced emulsification. Step 3: Adjust the pH to 8-9, and after high-speed shearing and ultrasonic emulsification to form a uniform sol, maintain it at 55-60℃ for 10-13 hours to obtain a stable, semi-transparent modified nano-Al2O3 polyvinyl alcohol sol. Step 4: Add the silicone abrasion resistant agent, cosolvent, wetting and leveling agent and defoamer in sequence, and stir well; Step 5: Add crosslinking agent and thickener to adjust viscosity to 200-500 mPa·s (25℃). Step 6: Let stand to defoam, filter, and obtain self-cleaning nano-sol coating solution.

[0015] The present invention provides a TPO substrate, characterized in that it includes the self-cleaning nanosol coating liquid, wherein the self-cleaning nanosol coating liquid is coated on the TPO substrate.

[0016] As a preferred technical solution, the self-cleaning nano-coating liquid is applied to the TPO substrate and cured by heating at 80-120℃ for 1-5 minutes to form a functional surface coating on the surface of the TPO substrate.

[0017] As a preferred technical solution, the coating method is scraping, roller coating, spraying, or dipping.

[0018] This invention also provides an application of a self-cleaning nano-sol coating liquid, which can be used in automotive interiors, outdoor tents, agricultural greenhouses, and temporary heat insulation and rainproof facilities.

[0019] The beneficial effects of this invention are: 1) Nano-Al2O3 forms a rigid framework between polyvinyl alcohol chains, while the organosilicon cross-linking network provides a flexible buffer, synergistically achieving the contradictory properties of high hardness and high toughness. By grafting nanoparticles with silane coupling agents, the contradiction between dispersion stability and transparency is resolved. 2) The micro-nano rough surface and low surface energy of the nano-Al2O3 structure enable the functional coating to be superhydrophobic and photocatalytically degrade pollutants, thus achieving self-cleaning; 3) Nano Al2O3 releases trace amounts of Al 3+ It disrupts the cell membranes of microorganisms, inhibiting their growth without the need for added organic antibacterial agents; 4) Using water as the dispersion medium, the VOC content is low, making it green and environmentally friendly. Detailed Implementation

[0020] The present invention will now be further described.

[0021] One embodiment of the present invention provides a self-cleaning nano-sol coating liquid, which, by weight, comprises 25-50 parts of modified nano-Al2O3 polyvinyl alcohol sol, 2-6 parts of organosilicon abrasion resistant agent, 1-3 parts of crosslinking agent, 1-3 parts of wetting and leveling agent, 3-7 parts of cosolvent, 20-40 parts of deionized water, and 1-3 parts of thickener. The cleaning nano-sol coating liquid is green and environmentally friendly, has high transparency, and good adhesion to TPO substrate.

[0023] Nano-Al2O3 forms a rigid framework between polyvinyl alcohol chains, while the organosilicon crosslinking network provides a flexible buffer, synergistically achieving the contradictory properties of high hardness and high toughness. After curing, it can form a dense, defect-free film or coating with good dispersion stability. The size of nano-Al2O3 particles is smaller than the wavelength of visible light, and after curing, it forms a transparent functional coating, resolving the contradiction between dispersion stability and transparency.

[0024] Organosilicon wear-resistant agents and crosslinking agents form an interpenetrating network, simultaneously improving wear resistance.

[0025] The micro-nano rough surface and low surface energy of nano-Al2O3 enable superhydrophobic functional coatings. Modified nano-Al2O3 polyvinyl alcohol sol provides surface hydroxyl groups, catalyzing the photodegradation of organic pollutants and achieving self-cleaning. Modified nano-Al2O3 polyvinyl alcohol sol also releases trace amounts of Al. 3+ It disrupts microbial cell membranes, providing long-lasting antibacterial properties without the need for added organic antibacterial agents.

[0026] In some preferred embodiments, the modified nano-Al2O3 polyvinyl alcohol sol has a nano-Al2O3 particle size of 10-50 nm and a degree of alcoholysis of polyvinyl alcohol of 88-99%.

[0027] In some preferred embodiments, the organosilicon wear-resistant agent is a hydroxyl-terminated or amino-modified organopolysiloxane emulsion. The organosilicon wear-resistant agent mainly imparts wear resistance and a comfortable feel to the material surface through chemical or physical actions. After being combined with modified nano-Al2O3 polyvinyl alcohol sol, it has the following effects: (1) improving surface wear resistance, lubrication and friction reduction: the organosilicon molecular chains are flexible and can form a lubricating layer on the material surface, reducing the coefficient of friction and reducing mechanical wear (such as friction and scratching); (2) anti-sticking: organosilicon molecules migrate to the material surface, forming a low surface energy layer, reducing surface adhesion. Avoid fingerprints and oil stains; (3) Enhance surface hydrophobicity: The hydrophobic groups of organosilicon reduce surface energy and form a "lotus effect", that is, the surface water contact angle is 110°-115° and the oil stain contact angle is >80°, which repels water, oil and anti-fouling coatings, outdoor textiles and other pollutants; (4) Improve surface stain resistance: Make the tent fabric surface easy to clean, stains are not easy to penetrate, and can be cleaned by wiping, extending the aesthetics of the material; (5) Improve weather resistance and chemical stability: Organosilicon is resistant to ultraviolet rays and high and low temperatures (-50-250℃), effectively resisting acids, alkalis, salt spray and other substances, extending service life.

[0028] In some preferred embodiments, the crosslinking agent is one of aziridine crosslinking agents, carbodiimide crosslinking agents, or blocked isocyanate crosslinking agents, which enhances the crosslinking density, forms a three-dimensional network structure, and improves water resistance and hardness.

[0029] In some preferred embodiments, the co-solvent is propylene glycol methyl ether, which adjusts the drying rate, avoids bubbles, reduces the surface tension of the aqueous coating system, and improves leveling uniformity.

[0030] In some preferred embodiments, the wetting and leveling agent is a polyether-modified siloxane, which eliminates coating defects, improves surface smoothness, and helps to increase transparency.

[0031] This invention also provides a method for preparing a self-cleaning nano-sol coating, comprising the following steps: Step 1: In a jacketed high-speed shear dispersion emulsification reactor, first prepare an 18-22% nitric acid solution, and slowly add nano-Al2O3 powder at a weight ratio of 1:(4-6). Pass hot water through the jacket and add 2-4 parts of silane coupling agent at 55-60℃. Perform high-speed shear emulsification at a speed of 1400-1600 r / min for 1.5-2.5 hours. After filtration, obtain a modified nano-Al2O3 dispersion. Step 2: Mix the modified nano-Al2O3 dispersion from Step 1 with a 1.5-2.5% polyvinyl alcohol solution, and perform high-speed shear emulsification and ultrasonic emulsification at 55-60℃ and a rotation speed of 2000-2500 r / min for forced emulsification for 2.5-3 hours. Step 3: Adjust the pH to 8-9, and after high-speed shearing and ultrasonic emulsification to form a uniform sol, maintain it at 55-60℃ for 10-13 hours to obtain a stable semi-transparent modified nano-Al2O3 polyvinyl alcohol sol. Step 4: Add the silicone wear-resistant agent, cosolvent, wetting and leveling agent and defoamer in sequence, and stir at a speed of 800-1000 r / min until uniform; Step 5: Add crosslinking agent and thickener to adjust the viscosity to 200-500 mPa·s (25℃), and stir at a speed of 300-500 r / min; Step 6: Allow to stand and defoam, then filter through a 250-350 mesh filter to obtain a self-cleaning nano-sol coating solution.

[0032] After obtaining the self-cleaning nanosol coating solution, stir continuously at 50-150 r / min and maintain the temperature at 35℃-40℃ for coating TPO substrate.

[0033] The nano-Al2O3 particles have a size of 10-50 nm, and the degree of alcoholysis of polyvinyl alcohol is 88-99%.

[0034] The present invention also provides a TPO substrate, comprising the self-cleaning nanosol coating liquid, wherein the self-cleaning nanosol coating liquid is coated on the TPO substrate.

[0035] As a preferred technical solution, the self-cleaning nano-coating liquid is applied to the TPO substrate and cured by heating at 80-120℃ for 1-5 minutes to form a functional surface coating on the surface of the TPO substrate.

[0036] As a preferred technical solution, the coating method is scraping, roller coating, spraying, or dipping.

[0037] This invention also provides an application of a self-cleaning nano-sol coating, characterized in that it is applied to automotive interiors, outdoor tents, agricultural greenhouses, and temporary insulation and rainproof facilities.

[0038] Example 1 A self-cleaning nano-sol coating liquid, by weight, comprises 25 parts of modified nano-Al2O3 polyvinyl alcohol sol, 2 parts of organosilicon abrasion resistant agent, 1 part of crosslinking agent, 1 part of wetting and leveling agent, 3 parts of cosolvent, 20 parts of deionized water, and 1 part of thickener.

[0039] A method for preparing a self-cleaning nanosol coating includes the following steps: Step 1: In a jacketed high-speed shear dispersion emulsification reactor, first prepare an 18-22% nitric acid solution, then slowly add nano-Al2O3 powder at a weight ratio of 1:4. Circulate hot water through the jacket and add 2 parts of silane coupling agent at 55°C. Emulsify at a high speed of 1400 r / min for 1.5 hours. After filtration through a 300-mesh filter, obtain the modified nano-Al2O3 dispersion. Step 2: Mix the modified nano-Al2O3 dispersion from Step 1 with a 1.5% polyvinyl alcohol solution, and perform high-speed shear emulsification and ultrasonic emulsification at 2000 r / min at 55°C for 2.5 hours. Step 3: Adjust the pH to 8, and after high-speed shearing and ultrasonic emulsification to form a uniform sol, maintain it at 55°C for 10 hours to obtain a stable semi-transparent modified nano-Al2O3 polyvinyl alcohol sol. Step 4: Add the silicone wear-resistant agent, cosolvent, wetting and leveling agent and defoamer in sequence, and stir at 800 r / min until uniform; Step 5: Add crosslinking agent and thickener to adjust viscosity to 200 mPa·s (25℃), and stir at 300 r / min; Step 6: Allow to stand and defoam, then filter through a 250-mesh filter to obtain a self-cleaning nano-sol coating solution.

[0040] The nano-Al2O3 particles have a diameter of 10 nm, the degree of alcoholysis of polyvinyl alcohol is 88%, the organosilicon wear-resistant agent is a hydroxyl-terminated organopolysiloxane emulsion, the crosslinking agent is an aziridine crosslinking agent, the silane coupling agent is KH-560, the wetting and leveling agent is a polyether-modified siloxane, the cosolvent is propylene glycol methyl ether, and the thickener is polyacrylate.

[0041] A TPO substrate includes the self-cleaning nanosol coating liquid, which is applied to the TPO substrate and cured by heating at 80°C for 1 minute, thereby forming a functional surface coating on the surface of the TPO substrate.

[0042] Example 2 A self-cleaning nano-sol coating, by weight, comprises 40 parts of modified nano-Al2O3 polyvinyl alcohol sol, 4 parts of organosilicon abrasion resistant agent, 2 parts of crosslinking agent, 3 parts of silane coupling agent, 2 parts of wetting and leveling agent, 4 parts of cosolvent, 30 parts of deionized water, and 2 parts of thickener.

[0043] A method for preparing a self-cleaning nanosol coating includes the following steps: Step 1: In a jacketed high-speed shear dispersion emulsification reactor, first prepare an 18-22% nitric acid solution, then slowly add nano-Al2O3 powder at a weight ratio of 1:5. Add 3 parts of silane coupling agent by passing hot water through the jacket at 58°C, and emulsify at a high speed of 1500 r / min for 2 hours. After filtration through a 300 mesh, obtain the modified nano-Al2O3 dispersion. Step 2: Mix the modified nano-Al2O3 dispersion from Step 1 with a 2% polyvinyl alcohol solution, and perform high-speed shear emulsification and ultrasonic emulsification at 58°C and a rotation speed of 2300 r / min for 2.6 hours. Step 3: Adjust the pH to 8-9, and after high-speed shearing and ultrasonic emulsification to form a uniform sol, maintain it at 58℃ for 10-13 hours to obtain a stable semi-transparent modified nano-Al2O3 polyvinyl alcohol sol. Step 4: Add the silicone wear-resistant agent, cosolvent, wetting and leveling agent and defoamer in sequence, and stir at 900 r / min until uniform; Step 5: Add crosslinking agent and thickener to adjust the viscosity to 300 mPa·s (25℃), and stir at 450 r / min; Step 6: Allow to stand and defoam, then filter through a 300-mesh filter to obtain a self-cleaning nano-sol coating solution.

[0044] The nano-Al2O3 particles have a diameter of 30 nm, the degree of alcoholysis of polyvinyl alcohol is 90%, the organosilicon wear-resistant agent is an amino-modified organopolysiloxane emulsion, the crosslinking agent is a blocked isocyanate crosslinking agent, the silane coupling agent is KH-570, the wetting and leveling agent is a polyether-modified siloxane, the cosolvent is propylene glycol methyl ether, and the thickener is polyacrylate.

[0045] A TPO substrate includes the self-cleaning nanosol coating liquid, which is applied to the TPO substrate and cured by heating at 100°C for 3 minutes to form a functional surface coating on the surface of the TPO substrate.

[0046] Example 3 A self-cleaning nano-sol coating, by weight, comprises 50 parts of modified nano-Al2O3 polyvinyl alcohol sol, 6 parts of organosilicon abrasion resistant agent, 3 parts of crosslinking agent, 4 parts of silane coupling agent, 3 parts of wetting and leveling agent, 7 parts of cosolvent, 40 parts of deionized water, and 3 parts of thickener.

[0047] A method for preparing a self-cleaning nanosol coating includes the following steps: Step 1: In a jacketed high-speed shear dispersion emulsification reactor, first prepare an 18-22% nitric acid solution, then slowly add nano-Al2O3 powder at a weight ratio of 1:6. Circulate hot water through the jacket and add 4 parts of silane coupling agent at 60°C. Emulsify at a high speed of 1600 r / min for 2.5 hours. After filtration through a 300-mesh filter, obtain the modified nano-Al2O3 dispersion. Step 2: Mix the modified nano-Al2O3 dispersion from Step 1 with a 2.5% polyvinyl alcohol solution, and perform high-speed shear emulsification and ultrasonic emulsification at 2500 r / min at 60℃ for 3 hours. Step 3: Adjust the pH to 9, and after high-speed shearing and ultrasonic emulsification to form a uniform sol, maintain it at 60℃ for 13 hours to obtain a stable semi-transparent modified nano-Al2O3 polyvinyl alcohol sol. Step 4: Add the silicone wear-resistant agent, cosolvent, wetting and leveling agent and defoamer in sequence, and stir at 1000 r / min until uniform; Step 5: Add crosslinking agent and thickener to adjust the viscosity to 500 mPa·s (25℃), and stir at 500 r / min; Step 6: Allow to stand and defoam, then filter through a 350-mesh filter to obtain a self-cleaning nano-sol coating solution.

[0048] The nano-Al2O3 particles have a diameter of 50 nm, the degree of alcoholysis of polyvinyl alcohol is 99%, the organosilicon wear-resistant agent is a hydroxyl-terminated or amino-modified organopolysiloxane emulsion, the crosslinking agent is a blocked isocyanate crosslinking agent, the silane coupling agent is KH-560, the wetting and leveling agent is a polyether-modified siloxane, the cosolvent is propylene glycol methyl ether, and the thickener is polyacrylate.

[0049] A TPO substrate includes the self-cleaning nanosol coating liquid, which is applied to the TPO substrate and cured by heating at 120°C for 5 minutes to form a functional surface coating on the surface of the TPO substrate.

[0050] The TPO substrates of Examples 1, 2 and 3 were tested, and the measured data met the data indicators in Table 1.

[0051] Table 1 When the TPO substrates of Examples 1, 2, and 3 are applied to the following products, the advantages are as follows: Outdoor tents: The functional coated TPO tarpaulin has a dust removal rate of >95% after being washed by rainwater; Agricultural greenhouses: No mold spots after 6 months of use, light transmittance decreases by less than 5%, significantly improving crop light efficiency; Temporary rain cover: The functional coating does not peel off after 50 folds and transports, and still maintains its stain resistance.

[0052] The above embodiments are merely descriptions for clearly illustrating the present invention and are not intended to limit the implementation. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively list all implementations here, and any obvious variations or modifications derived therefrom are still within the protection scope of the present invention.

Claims

1. A self-cleaning nano-sol coating solution, characterized in that, By weight, it includes 25-50 parts of modified nano-Al2O3 polyvinyl alcohol sol, 2-6 parts of organosilicon abrasion resistant agent, 1-3 parts of crosslinking agent, 1-3 parts of wetting and leveling agent, 3-7 parts of cosolvent, 20-40 parts of deionized water, and 1-3 parts of thickener.

2. The self-cleaning nanosol coating solution according to claim 1, characterized in that, The modified nano-Al2O3 polyvinyl alcohol sol has a nano-Al2O3 particle size of 10-50 nm and a degree of alcoholysis of 88-99% for polyvinyl alcohol.

3. The self-cleaning nanosol coating solution according to claim 1, characterized in that, The organosilicon wear-resistant agent is a hydroxyl-terminated or amino-modified organopolysiloxane emulsion.

4. The self-cleaning nanosol coating solution according to claim 1, characterized in that, The crosslinking agent is one of the following: aziridine crosslinking agents, carbodiimide crosslinking agents, or blocked isocyanate crosslinking agents.

5. The self-cleaning nanosol coating solution according to claim 1, characterized in that, The cosolvent is propylene glycol methyl ether.

6. A method for preparing a self-cleaning nanosol coating as described in any one of claims 2-5, characterized in that, Includes the following steps: Step 1: In a jacketed high-speed shear dispersion emulsification reactor, first prepare an 18-22% nitric acid solution, and slowly add nano-Al2O3 powder at a weight ratio of 1:(4-6). Circulate hot water through the jacket and add silane coupling agent at 55-60℃. Emulsify at a high-speed shear rate of 1400-1600 r / min for 1.5-2.5 hours. After filtration, obtain the modified nano-Al2O3 dispersion. Step 2: Mix the modified nano-Al2O3 dispersion from Step 1 with the polyvinyl alcohol solution, and subject it to high-speed shear emulsification and ultrasonic emulsification at 55-60℃ for 2.5-3 hours of forced emulsification. Step 3: Adjust the pH to 8-9, and after high-speed shearing and ultrasonic emulsification to form a uniform sol, maintain it at 55-60℃ for 10-13 hours to obtain a stable, semi-transparent modified nano-Al2O3 polyvinyl alcohol sol. Step 4: Add the silicone abrasion resistant agent, cosolvent, wetting and leveling agent and defoamer in sequence, and stir well; Step 5: Add crosslinking agent and thickener to adjust viscosity to 200-500 mPa·s (25℃). Step 6: Let stand to defoam, filter, and obtain self-cleaning nano-sol coating solution.

7. A TPO substrate, characterized in that, The self-cleaning nanosol coating liquid according to claims 1-6 is coated on the TPO substrate.

8. A method for preparing the TPO substrate as described in claim 7, characterized in that, The self-cleaning nano-coating liquid is applied to the TPO substrate and cured by heating at 80-120℃ for 1-5 minutes to form a functional surface coating on the TPO substrate surface.

9. The preparation method according to claim 8, characterized in that, The coating method is scraping, rolling, spraying, or dipping.

10. An application of the self-cleaning nanosol coating as described in claims 1-6, characterized in that, It is used in outdoor tents, agricultural greenhouses, and temporary insulation and rain protection facilities.

Images