A tpu car cover repair coating composition with double anti-fouling self-cleaning function and coating

Abstract

The application provides a TPU car coat repair coating composition and coating with double anti-fouling self-cleaning function. The TPU car coat repair coating composition comprises 60-80 parts of aliphatic polyurethane acrylate, 15-30 parts of active diluent, 1-5 parts of functionalized polysiloxane, 0.5-2 parts of block copolymer compatibilizer and 1-3 parts of photoinitiator in terms of mass fraction. The functionalized polysiloxane is selected from reactive silicone oil containing acrylate or epoxy groups in end groups or side chains. The application introduces polyether-polysiloxane block copolymer as a compatibilizer, the polyether segment of which is compatible with the polyurethane base, and the polysiloxane segment is similar to the functionalized polysiloxane, so that the polysiloxane is uniformly dispersed in the matrix in nanoscale size, and the phase separation phenomenon is avoided. In addition, the functionalized polysiloxane capped with acrylate or epoxy groups, the double bonds of which can participate in the UV curing crosslinking reaction, so that the siloxane layer and the coating body are connected through chemical bonds, and the anti-fouling performance and weather resistance are improved.

Description

Technical Field

[0001] This application relates to the field of resin coating materials technology, specifically to a TPU car cover repair coating composition and coating with dual anti-fouling and self-cleaning functions. Background Technology

[0002] As a high-performance protective material, automotive paint protection film has been widely used in the automotive market in recent years. Among them, thermoplastic polyurethane (TPU) substrate, with its excellent flexibility, weather resistance, and impact resistance, has become the mainstream substrate choice for high-end car covers. To further enhance the practical value of car covers, a repair coating is usually applied to the TPU surface. This coating can recover its original shape after minor scratches through heating or external force, thus maintaining the car cover's appearance for a long time. However, as consumers' demands for car cover performance continue to increase, simply possessing scratch repair capabilities is no longer sufficient to meet market needs. How to make the repair coating simultaneously possess excellent stain resistance and self-cleaning properties has become an urgent problem to be solved.

[0003] In existing technologies, a common method to impart antifouling properties to coatings is to introduce low surface energy substances, such as polysiloxanes and fluorocarbons, into the coating system. Polysiloxanes, due to their molecular structure containing a flexible Si-O backbone and hydrophobic organic side chains, possess extremely low surface tension, far lower than that of contaminants such as water, oil, and dust, and are therefore widely used in antifouling coating research. Theoretically, adding polysiloxanes to a repair coating allows them to spontaneously migrate and align to the coating surface during film formation, utilizing their extremely low surface tension to form a dense siloxane film, thus achieving an antifouling effect. However, directly adding polysiloxanes to polyurethane-based repair coatings still presents the following problems: First, polysiloxanes have poor compatibility with polyurethane resins. Direct addition can lead to phase separation in the coating, resulting in defects such as whitening, cloudiness, surface pinholes, or orange peel texture, which severely affect the transparency and decorative properties of the car wrap. Simultaneously, phase separation weakens the coating's cohesive strength, reducing scratch repair efficiency and causing insufficient interlayer adhesion, thus impacting the car wrap's lifespan. Second, the amount of polysiloxane added is difficult to balance between anti-fouling effects and repair performance. Third, the migration of polysiloxanes is difficult to precisely control. While non-reactive polysiloxanes can migrate to the surface, their bond with the coating matrix is ​​weak, making them prone to loss due to wiping, friction, or aging during long-term use, thus weakening anti-fouling properties. Existing technologies use highly cross-linked rigid coatings to fix the siloxane components, but this reduces the coating's elasticity and self-healing properties.

[0004] Therefore, it is of great significance to provide a TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions, and to achieve a synergistic improvement in anti-fouling performance and repair performance through component design and ratio optimization. Summary of the Invention

[0005] To address the shortcomings of existing technologies, this application provides a TPU car cover repair coating composition and coating with dual anti-fouling and self-cleaning functions, which solves the problems mentioned in the background art.

[0006] To achieve the above objectives, this application provides the following technical solution: According to a first aspect of this application, a TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions is provided, comprising, by weight parts, 60-80 parts of aliphatic polyurethane acrylate, 15-30 parts of reactive diluent, 1-5 parts of functionalized polysiloxane, 0.5-2 parts of block copolymer compatibilizer, and 1-3 parts of photoinitiator. The functionalized polysiloxane is selected from reactive silicone oils with end groups or side chains containing acrylates or epoxy groups.

[0007] This application introduces a specific proportion of acrylate-functionalized polysiloxane as an anti-fouling functional component into an aliphatic polyurethane acrylate repair coating system, while simultaneously compounding a polyether-polysiloxane front copolymer as a compatibilizer. Through the synergistic effect of the two, the siloxane component achieves a controllable gradient migration and chemical anchoring from the bulk to the surface during the curing process, ultimately forming a structure with an integrated bulk repair layer and a surface siloxane functional layer, which can simultaneously resolve the contradiction between compatibility, anti-fouling performance, and repair performance.

[0008] Preferably, the amount of the functionalized polysiloxane added is 2 to 3.5 parts; The functional group polysiloxane has a molecular weight of 2000~5000.

[0009] In this range of functionalized polysiloxanes, the siloxane components, during the curing process, utilize their low surface tension to spontaneously migrate to the coating surface and oriented, forming a dense siloxane surface layer with a thickness of 10~50nm. This gives the coating excellent superhydrophobic, oleophobic, and low-tack properties, while the coating body also maintains the high elasticity and cross-linked network structure of polyurethane acrylate, ensuring that the scratch repair function is not affected.

[0010] Preferably, the block copolymer compatibilizer is a polyether-polysiloxane block copolymer; The amount of the block copolymer compatibilizer added is 20-40% of the functionalized polysiloxane.

[0011] Because the polyether-polysiloxane block copolymer compatibilizer has good compatibility with the polyurethane matrix, the polysiloxane segments and functionalized polysiloxanes act as molecular bridges in the system, connecting the two incompatible phases at the nanoscale, effectively preventing phase separation. This allows the polysiloxane to be uniformly dispersed in the polyurethane matrix at the nanoscale, ensuring the transparency of the coating and avoiding appearance defects such as whitening, turbidity, surface pinholes, or orange peel caused by phase separation.

[0012] Preferably, the polyether-polysiloxane block copolymer is selected from at least one of polydimethylsiloxane-polyoxyalkane olefin block copolymer and dimethylsiloxane-b-ethylene glycol block copolymer.

[0013] Preferably, the reactive diluent is selected from a compound of difunctional acrylate monomers and monofunctional acrylate monomers, wherein the difunctional acrylate monomer is selected from at least one of 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, and 1,10-decanediol diacrylate, and the monofunctional acrylate monomer is selected from at least one of isobornyl acrylate, isooctyl acrylate, and lauryl acrylate.

[0014] Preferably, the TPU car cover repair coating composition further includes 0.2 to 2 parts of nanofiller, wherein the nanofiller is nano-silica with surface methylation modification, and the particle size of the nanofiller is 20 to 50 nm.

[0015] Preferably, the TPU car wrap repair coating composition further includes 0.1 to 0.5 parts of additives, including leveling agents and defoamers.

[0016] Preferably, the photoinitiator is selected from 2-hydroxy-2-methyl-1-phenylpropanone.

[0017] According to a second aspect of this application, a TPU car cover repair coating with dual anti-fouling and self-cleaning functions is provided, which is formed by coating, static leveling and curing of the above-mentioned TPU car cover repair coating composition, wherein the static leveling temperature is 40~60°C and the time is 30~60s.

[0018] This application provides sufficient migration time for siloxane segments by setting process parameters for static leveling, enabling them to complete orderly arrangement before chemical anchoring and achieving precise control of the migration process.

[0019] Preferably, the TPU car wrap repair coating includes a coating body and a siloxane layer enriched on the surface of the coating body after curing, wherein the siloxane layer is connected to the coating body by chemical bonds.

[0020] Preferably, the thickness of the siloxane layer is 10~50 nm; The TPU car cover repair coating has a water contact angle ≥108°, a surface energy ≤23.5mN / m, and a scratch recovery rate ≥92% after heating at 80℃ for 5 minutes.

[0021] This application provides a TPU car cover repair coating composition and coating with dual anti-fouling and self-cleaning functions. It has the following beneficial effects: (1) The TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions provided in this solution introduces polyether-polysiloxane block copolymer as a compatibilizer. Its polyether segments are compatible with polyurethane groups, and its polysiloxane segments are similar to functionalized polysiloxanes, playing a bridging role, so that the polysiloxanes are uniformly dispersed in the matrix at the nanoscale, avoiding phase separation. In addition, the functionalized polysiloxanes with acrylate or epoxy end caps are used, and their double bonds can participate in the UV curing crosslinking reaction, so that the siloxane layer and the coating body are connected by chemical bonds, which can effectively prevent the failure of the siloxane layer and improve the anti-fouling performance and weather resistance.

[0022] (2) The TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions provided by this solution, by controlling the active diluent and functionalized polysiloxane, ensures that the coating composition can form a continuous and dense covering layer on the surface of the siloxane component without affecting the repair performance and cohesive strength of the coating.

[0023] (3) The TPU car cover repair coating with dual anti-fouling and self-cleaning functions provided by this solution combines static leveling process before curing, so that the polysiloxane component in the composition can fully migrate to the surface and arrange in an orderly manner before curing, forming a siloxane-rich layer with a surface energy of less than 23.5 mN / m. It has excellent hydrophobic and oleophobic properties. Moreover, the siloxane-rich layer is only enriched in a very thin layer on the surface of the body, and will not affect the cross-linking network and chain segment movement performance of the polyurethane acrylate body. After heating at 80°C for 5 minutes, the scratch recovery rate can reach more than 92%, which has both anti-fouling, self-cleaning and repair performance.

[0024] (4) The TPU car cover repair coating with dual anti-fouling and self-cleaning functions provided by this solution has high transparency after curing, with a light transmittance of over 92.5%, no whitening, no haze, and no pinholes. The coating surface is smooth and has excellent touch and gloss. Detailed Implementation

[0025] To better illustrate the content of this application, the following description is provided in conjunction with specific embodiments.

[0026] In the following embodiments and comparative examples of this application, the raw materials used are all commercially available products, as detailed below: The functionalized polysiloxane is selected from acrylate-terminated polydimethylsiloxane with a molecular weight of 3000; the block copolymer compatibilizer is selected from polydimethylsiloxane-polyoxyalkylene block copolymer; the photoinitiator is selected from 2-hydroxy-2-methyl-1-phenylpropanone; the nano silica is selected from surface-methylated modified nano silica with a particle size of 20~50nm; the leveling agent is selected from polyacrylate leveling agents; and the defoamer is selected from polysiloxane defoamers.

[0027] The embodiments and comparative examples of this application were prepared according to the following steps: Step 1: Mix the components according to the formula and disperse them evenly at high speed to obtain the coating composition; Step 2: Coat the composition onto the surface of a TPU substrate, with a wet film thickness of 50 μm; Step 3: Allow the mixture to stand at 50℃ for 45 seconds to level. Step 4: Use ultraviolet light to cure the coating to obtain a dry film thickness of approximately 20~35μm.

[0028] Example 1 A TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions comprises, by weight, 70 parts aliphatic polyurethane acrylate, 20 parts 1,6-hexanediol diacrylate and isobornyl acrylate in a 1:1 weight ratio, 2 parts acrylate-terminated polydimethylsiloxane with a molecular weight of 3000, 0.5 parts polydimethylsiloxane-polyoxyalkylene block copolymer, 2 parts 2-hydroxy-2-methyl-1-phenylpropanone, 1 part nano-silica, 0.3 parts leveling agent and 0.2 parts defoamer.

[0029] Example 2 A TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions comprises, by weight, 70 parts aliphatic polyurethane acrylate, 20 parts 1,6-hexanediol diacrylate and isooctyl acrylate in a 1:1 weight ratio, 3 parts acrylate-terminated polydimethylsiloxane with a molecular weight of 3000, 1 part polydimethylsiloxane-polyoxyalkylene block copolymer, 2 parts 2-hydroxy-2-methyl-1-phenylpropanone, 1 part nano-silica, 0.3 parts leveling agent and 0.2 parts defoamer.

[0030] Example 3 A TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions comprises, by weight, 70 parts aliphatic polyurethane acrylate, 20 parts 1,9-nonanediol diacrylate and lauryl acrylate in a 1:1 weight ratio, 3.5 parts acrylate-terminated polydimethylsiloxane with a molecular weight of 3000, 1.2 parts polydimethylsiloxane-polyoxyalkylene block copolymer, 2 parts 2-hydroxy-2-methyl-1-phenylpropanone, 1 part nano-silica, 0.3 parts leveling agent, and 0.2 parts defoamer.

[0031] Example 4 A TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions comprises, by weight, 65 parts aliphatic polyurethane acrylate, 25 parts 1,10-decyl glycol diacrylate and isoborneol acrylate in a 1:1 weight ratio, 2.5 parts acrylate-terminated polydimethylsiloxane with a molecular weight of 3000, 0.8 parts polydimethylsiloxane-polyoxyalkylene block copolymer, 2 parts 2-hydroxy-2-methyl-1-phenylpropanone, 1.5 parts nano-silica, 0.3 parts leveling agent, and 0.2 parts defoamer.

[0032] Example 5 A TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions comprises, by weight, 75 parts aliphatic polyurethane acrylate, 18 parts 1,6-hexanediol diacrylate and isobornyl acrylate in a 1:1 weight ratio, 4 parts acrylate-terminated polydimethylsiloxane with a molecular weight of 3000, 1.6 parts polydimethylsiloxane-polyoxyalkylene block copolymer, 2 parts 2-hydroxy-2-methyl-1-phenylpropanone, 0.5 parts nano-silica, 0.3 parts leveling agent, and 0.2 parts defoamer.

[0033] Comparative Example 1 A TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions comprises, by weight, 70 parts aliphatic polyurethane acrylate, 20 parts 1,6-hexanediol diacrylate and isobornyl acrylate in a 1:1 weight ratio, 2 parts acrylate-terminated polydimethylsiloxane with a molecular weight of 3000, 2 parts 2-hydroxy-2-methyl-1-phenylpropanone, 1 part nano silica, 0.3 parts leveling agent and 0.2 parts defoamer.

[0034] Comparative Example 2 A TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions comprises, by weight, 70 parts aliphatic polyurethane acrylate, 20 parts 1,6-hexanediol diacrylate and isooctyl acrylate in a 1:1 weight ratio, 8 parts acrylate-terminated polydimethylsiloxane with a molecular weight of 3000, 2 parts polydimethylsiloxane-polyoxyalkylene block copolymer, 2 parts 2-hydroxy-2-methyl-1-phenylpropanone, 1 part nano-silica, 0.3 parts leveling agent and 0.2 parts defoamer.

[0035] Comparative Example 3 A TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions comprises, by weight, 70 parts aliphatic polyurethane acrylate, 20 parts 1,6-hexanediol diacrylate and isooctyl acrylate in a 1:1 weight ratio, 3 parts non-reactive polysiloxane with a molecular weight of 3000, 1 part polydimethylsiloxane-polyoxyalkylene block copolymer, 2 parts 2-hydroxy-2-methyl-1-phenylpropanone, 1 part nano-silica, 0.3 parts leveling agent and 0.2 parts defoamer.

[0036] The TPU car cover repair coatings with dual anti-fouling and self-cleaning functions prepared in Examples 1 to 5 and Comparative Examples 1 to 3 were tested respectively, and the test results are shown in Table 1.

[0037] Visually inspect the coating surface to check for transparency, whitening, pinholes, orange peel, and other defects. Deionized water was added to the coating surface at room temperature using the seated drop method, and the water contact angle was tested. Surface energy was calculated using the OWRK method with water and diiodomethane as test liquids. Use an oil-based marker to write and observe the ink shrinkage and residue after wiping; The scratch disappearance rate was calculated after the coating surface was scratched with a 500g load and then heated at 80℃ for 5 minutes. The transmittance was tested using a transmittance meter. The adhesion was tested by peeling the scratched surface with 3M tape using the cross-cut adhesion test. The water contact angle was tested by rubbing the water 1000 times with steel wool under a load of 1000g for 1000 cycles.

[0038] Table 1

[0039] As shown in the table above, this application effectively solves the compatibility problem between polysiloxane and polyurethane by introducing a block copolymer compatibilizer, which can ensure the high transparency and appearance quality of the coating. When the amount of functionalized polysiloxane added is controlled within the range of 2.0~3.5, the coating can achieve better anti-fouling performance and repair performance. The use of acrylate-terminated non-hardening polysiloxane, which is anchored to the bulk network through chemical bonds, significantly improves the anti-fouling performance and durability.

[0040] Although embodiments of this application have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of this application, the scope of which is defined by the appended claims and their equivalents.

Claims

1. A TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions, characterized in that: By weight, it includes 60-80 parts of aliphatic polyurethane acrylate, 15-30 parts of reactive diluent, 1-5 parts of functionalized polysiloxane, 0.5-2 parts of block copolymer compatibilizer, and 1-3 parts of photoinitiator. The functionalized polysiloxane is selected from reactive silicone oils with end groups or side chains containing acrylates or epoxy groups.

2. The TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions according to claim 1, characterized in that: The amount of the functionalized polysiloxane added is 2 to 3.5 parts; The functional group polysiloxane has a molecular weight of 2000~5000.

3. The TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions according to claim 1, characterized in that: The block copolymer compatibilizer is a polyether-polysiloxane block copolymer; The amount of the block copolymer compatibilizer added is 20-40% of the functionalized polysiloxane.

4. The TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions according to claim 3, characterized in that: The polyether-polysiloxane block copolymer is selected from at least one of polydimethylsiloxane-polyoxyalkane olefin block copolymer and dimethylsiloxane-b-ethylene glycol block copolymer.

5. The TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions according to claim 1, characterized in that: The reactive diluent is selected from a compound of difunctional acrylate monomers and monofunctional acrylate monomers, wherein the difunctional acrylate monomer is selected from at least one of 1,6-hexanediol diacrylate, 1,9-nonanediol diacrylate, and 1,10-decanediol diacrylate, and the monofunctional acrylate monomer is selected from at least one of isobornyl acrylate, isooctyl acrylate, and lauryl acrylate.

6. The TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions according to claim 1, characterized in that: The TPU car cover repair coating composition further includes 0.2 to 2 parts of nanofiller, wherein the nanofiller is nano-silica with surface methylation modification, and the particle size of the nanofiller is 20 to 50 nm.

7. The TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions according to claim 1, characterized in that: The TPU car wrap repair coating composition further includes 0.1 to 0.5 parts of additives, including leveling agents and defoamers.

8. A TPU car cover repair coating with dual anti-fouling and self-cleaning functions, characterized in that: The TPU car cover repair coating composition with dual anti-fouling and self-cleaning functions as described in any one of claims 1 to 7 is applied, allowed to stand and level, and then cured to form the coating. The standing and leveling temperature is 40~60℃ and the time is 30~60s.

9. A TPU car cover repair coating with dual anti-fouling and self-cleaning functions according to claim 8, characterized in that: The TPU car wrap repair coating includes a coating body and a siloxane layer enriched on the surface of the coating body after curing. The siloxane layer is connected to the coating body by chemical bonds.

10. A TPU car cover repair coating with dual anti-fouling and self-cleaning functions according to claim 9, characterized in that: The thickness of the siloxane layer is 10~50 nm; The TPU car cover repair coating has a water contact angle ≥108°, a surface energy ≤23.5mN / m, and a scratch recovery rate ≥92% after heating at 80℃ for 5 minutes.

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