Self-repairing invisible car paint and preparation method thereof

Abstract

The application relates to a self-repairing invisible car paint and a preparation method thereof, and relates to the technical field of automobile material processing. The car paint comprises the following components in mass fractions: fluorine-containing polyol 20-40 parts, polyisocyanate 15-30 parts, composite chain extender 5-10 parts, self-repairing microcapsule 10-20 parts, initiator 1-3 parts and solvent 30-50 parts. The preparation method comprises the following steps: preparing self-repairing paint; coating an adhesive to the surface of a transparent substrate to obtain an adhesive layer, and then coating a release film on the adhesive layer to obtain a car paint semi-finished product; coating the self-repairing paint to the side of the car paint semi-finished product far from the release film, heating and curing to obtain a car paint semi-finished product with a self-repairing coating, coating a protective film on the self-repairing coating, and aging to obtain the self-repairing invisible car paint. The application has the effect of improving the self-repairing performance of the car paint, and the car paint has good weather resistance, tensile resistance and puncture resistance.

Description

Technical Field

[0001] This application relates to the field of automotive material processing technology, and in particular to a self-healing invisible car wrap and its preparation method. Background Technology

[0002] Paint protection film, as an effective tool for protecting car surfaces from scratches, corrosion, and other damage, is widely used in the automotive detailing and protection market. With consumers' increasing demand for vehicle exterior protection, the market demand for paint protection film is also growing year by year.

[0003] Traditional paint protection film (PPF) mainly consists of one or more layers of polymer materials, protecting the paint through physical coverage. It primarily includes two types: single-layer polymer materials and multi-layer composite materials. Single-layer polymer materials typically use materials such as polyurethane and polyvinyl chloride, which have a certain degree of flexibility and weather resistance, but their scratch resistance is relatively weak and they are easily affected by environmental factors, leading to aging. Multi-layer composite materials, on the other hand, enhance the overall performance of the product by layering different functional materials.

[0004] While existing paint protection film can protect the paint to some extent, it lacks effective self-healing capabilities when faced with minor scratches and wear, resulting in a short lifespan and high maintenance costs, thus requiring improvement. Summary of the Invention

[0005] To improve the self-healing performance of paint protection film, this application provides a self-healing paint protection film and its preparation method.

[0006] This application provides a self-healing paint protection film and its preparation method, which adopts the following technical solution:

[0007] Firstly, this application provides a self-healing paint protection film, which adopts the following technical solution:

[0008] A self-healing paint protection film includes a protective film, a self-healing coating, a transparent substrate, an adhesive layer, and a release film arranged sequentially. The self-healing coating is obtained by applying a self-healing paint, and the raw materials for preparing the self-healing paint include the following components in parts by weight:

[0009] 20-40 parts of fluorinated polyols

[0010] 15-30 parts of polyisocyanate

[0011] 5-10 parts of compound chain extender

[0012] 10-20 doses of self-repairing microcapsules

[0013] 1-3 parts of initiator

[0014] Solvent 30-50 parts.

[0015] Fluorinated polyols, by introducing fluorine atoms, lower the surface energy, enhancing the weather resistance and chemical corrosion resistance of the car cover, making it less prone to stain adhesion. Polyisocyanates react with fluorinated polyols to form a polyurethane network structure, providing the coating with excellent mechanical strength and stability, thus improving the car cover's scratch resistance. Composite chain extenders effectively regulate the length and structure of the polyurethane chains, enhancing the car cover's flexibility and tensile properties, making it less prone to breakage under external stretching or bending. Self-healing microcapsules are uniformly dispersed in the coating; when minor damage such as scratches occurs on the car cover surface, the microcapsules rupture, releasing repair substances to repair the damaged areas and restore the car cover's integrity and protective function. Through the synergistic effect of all components, the self-healing invisible car cover can achieve rapid self-repair after damage, effectively reducing damage to the paint during long-term use, and offering a long service life and excellent aesthetics.

[0016] Preferably, the raw materials for preparing the fluorinated polyol include bio-based polyols and perfluorohexyl propylene oxide.

[0017] Perfluorohexyl propylene oxide introduces fluorine atoms, giving the material a unique molecular structure that allows the molecular chains to rearrange after being damaged by scratches or other injuries, promoting the adjustment of the damaged molecular chains back to their original state and enhancing self-healing properties. The presence of fluorine improves the car cover's UV resistance, effectively absorbing and scattering ultraviolet rays to prevent damage to the molecules in the material. At the same time, the fluorine-containing groups enhance the material's chemical stability and improve weather resistance. The network structure formed by the polymerization of bio-based polyols and perfluorohexyl propylene oxide has good flexibility and cohesion. The dense structure formed by the fluorine-containing polyols enhances the overall hardness and toughness of the car cover, improving its tensile and puncture resistance, effectively resisting external damage, and extending the car cover's service life.

[0018] Preferably, the mass ratio of the bio-based polyol to perfluorohexyl propylene oxide is 1:(0.1-0.3).

[0019] The fluorinated polyol prepared according to the above mass ratio has good properties and can effectively improve the self-healing performance, weather resistance, tensile strength and puncture resistance of paint protection film.

[0020] Preferably, the composite chain extender comprises 4,4'-diaminodiphenyl disulfide and modified magnolol chain extender.

[0021] 4,4'-Diaminodiphenyl disulfide increases the length and cross-linking degree of molecular chains, resulting in more interaction points between molecular chains. Amino groups and other functional groups can form hydrogen bonds within the coating system. The phenolic hydroxyl groups in modified magnolol can also promote more orderly movement and rearrangement of molecular chains through hydrogen bonding, thereby repairing scratches and enhancing the self-healing properties of the paint protection film. Modified magnolol has excellent antioxidant properties, resisting the erosion of the film by environmental factors such as ultraviolet rays and oxygen in the air. Furthermore, the chemical bond structure in 4,4'-diaminodiphenyl disulfide is stable. The combined effect of these two factors reduces aging and degradation caused by long-term exposure to the external environment, improving the weather resistance of the film. The increased cross-linking degree and intermolecular interactions enhance the overall strength of the paint protection film, allowing the molecular chains to share the stress and evenly distribute it when subjected to external forces, preventing excessive local stress that could lead to film breakage, better protecting the paint, and improving tensile and puncture resistance.

[0022] Preferably, the raw materials for preparing the modified magnolol chain extender include magnolol bulk, silane coupling agent and nano-silica.

[0023] Nano-silica modified magnolol, with silane coupling agents acting as bridges, effectively introduces uniformly dispersed nano-silica into the coating. Nano-silica reinforces defects in the molecular chains, enhancing their strength and providing physical space and constraint for chain movement. When the car cover is damaged, it encourages more orderly repositioning and rearrangement to repair scratches. Nano-silica enhances the car cover's ability to reflect and scatter ultraviolet rays, reducing UV damage to its internal structure. Magnolol improves antioxidant properties; their synergistic effect extends the car cover's lifespan and improves its weather resistance. Modified magnolol chain extenders introduce nano-silica into the coating's molecular chains, and the combination of the two allows the car cover to effectively disperse stress, reducing cracks and punctures, and further extending its lifespan.

[0024] Preferably, the modified honokiol chain extender is prepared using the following steps:

[0025] Nano-silica was dispersed in anhydrous ethanol and sonicated to obtain a nano-silica dispersion. A silane coupling agent was dispersed in water, the pH was adjusted to acidic, and the mixture was stirred to obtain a hydrolyzed silane coupling agent solution. Magnolol and the hydrolyzed silane coupling agent solution were added to the nano-silica dispersion, and the mixture was heated and stirred to react. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain a modified magnolol chain extender.

[0026] The modified magnolol chain extender prepared according to the above steps can effectively improve the self-healing performance, weather resistance, tensile strength and puncture resistance of paint protection film.

[0027] Preferably, the raw materials for preparing the self-healing microcapsules include modified polyamines and urea-formaldehyde resin.

[0028] When the car cover is scratched or damaged, the self-healing microcapsules rupture, releasing modified polyamines. The active groups in the modified polyamines can react chemically with other components in the car cover material to form new chemical bonds, repairing the damaged areas and enhancing the self-healing performance of the paint protection film. Urea-formaldehyde resin has good chemical stability and can resist the erosion of external factors such as ultraviolet rays and moisture, protecting the modified polyamines. When damage occurs, the modified polyamines are released to repair scratches, allowing the car cover to maintain good working performance and appearance for a long time, thus extending the lifespan of the car cover.

[0029] Preferably, the raw materials for preparing the modified polyamine include diethylenetriamine and maleimide.

[0030] Diethylenetriamine contains multiple active amino groups, and maleimide contains carbon-carbon double bonds and imide groups. The modified polyamine formed by their reaction has abundant reactive sites. When scratches appear on the surface of the car cover, the microcapsules rupture, and the modified polyamine is released. Its active sites can react with the active groups in the car cover system to form new cross-linked structures at the damaged site, thereby achieving the repair function. The modified polyamine can also form connections with surrounding molecules through hydrogen bonding, promoting the self-repair of the car cover and improving its self-repair performance. By introducing imide groups, the modified polyamine improves thermal and chemical stability, and the repaired cracks after release have high strength, which can reduce the phenomenon of re-breakage due to external forces.

[0031] Preferably, the mass ratio of diethylenetriamine to maleimide is 1:(0.8-1).

[0032] The modified polyamine prepared according to the above mass ratio has good self-healing properties.

[0033] Secondly, this application provides a method for preparing a self-healing paint protection film, which adopts the following technical solution:

[0034] A method for preparing a self-healing paint protection film includes the following steps:

[0035] Under a neutral gas atmosphere, polyisocyanate was added to a fluorinated polyol while heating and stirring. After reaction, a prepolymer was obtained. A composite chain extender was dissolved in a solvent to obtain a chain extender dispersion. The chain extender dispersion was added to the prepolymer, and the mixture was heated and stirred to obtain a polymer. An initiator was dissolved in a solvent to obtain an initiator solution. Self-healing microcapsules were added to the polymer, and the mixture was heated and stirred to react. Then, the initiator solution was added, and the mixture was heated and stirred to react. After cooling, the mixture was discharged to obtain a self-healing coating.

[0036] An adhesive is applied to the surface of a transparent substrate to obtain an adhesive layer. A release film is then applied to the adhesive layer to obtain a semi-finished car cover. A self-healing coating is applied to the side of the semi-finished car cover away from the release film and cured by heating to obtain a semi-finished car cover with a self-healing coating. A protective film is then applied to the self-healing coating and cured to obtain a self-healing invisible car cover.

[0037] The self-healing paint protection film prepared according to the above steps has good self-healing properties, weather resistance, tensile strength and puncture resistance, has a long service life, can resist damage from external stress during use, and maintains good aesthetics.

[0038] In summary, this application includes at least one of the following beneficial technical effects:

[0039] 1. Fluorinated polyols, by introducing fluorine atoms, lower the surface energy, enhancing the weather resistance and chemical corrosion resistance of the car cover, making it less prone to stain adhesion. Polyisocyanates react with fluorinated polyols to form a polyurethane network structure, providing the coating with excellent mechanical strength and stability, thus improving the car cover's scratch resistance. Composite chain extenders effectively regulate the length and structure of the polyurethane chains, enhancing the car cover's flexibility and tensile properties, making it less prone to breakage under external stretching or bending. Self-healing microcapsules are uniformly dispersed in the coating; when minor damage such as scratches occurs on the car cover surface, the microcapsules rupture, releasing repair substances to repair the damaged areas and restore the car cover's integrity and protective function. Through the synergistic effect of all components, the self-healing invisible car cover can achieve rapid self-repair after damage, effectively reducing damage to the paint during long-term use, resulting in a long service life and excellent aesthetics.

[0040] 2. Perfluorohexyl propylene oxide introduces fluorine atoms, giving the material a unique molecular structure that allows the molecular chains to rearrange after scratches or other damage, promoting the adjustment of the damaged molecular chains back to their original state and enhancing self-healing properties. The presence of fluorine improves the car cover's UV resistance, effectively absorbing and scattering ultraviolet rays to prevent damage to the material molecules. Simultaneously, the fluorine-containing groups enhance the material's chemical stability and improve weather resistance. The network structure formed by the polymerization of bio-based polyols and perfluorohexyl propylene oxide possesses excellent flexibility and cohesion. The dense structure formed by the fluorinated polyols enhances the overall hardness and toughness of the car cover, improving its tensile and puncture resistance, effectively resisting external damage and extending its service life.

[0041] 3. Nano-silica modified magnolol, with silane coupling agent acting as a bridge, can effectively introduce uniformly dispersed nano-silica into the coating. Nano-silica can reinforce defects in the molecular chain, improve its strength, and provide physical space and constraint for the movement of the molecular chain. When the car cover is damaged, it prompts the car cover to adjust its position more orderly and rearrange to repair scratches. Nano-silica can enhance the car cover's ability to reflect and scatter ultraviolet rays, reducing the damage of ultraviolet rays to the internal structure of the car cover. Magnolol can improve antioxidant properties. The two work synergistically to extend the service life of the car cover and improve its weather resistance. Modified magnolol chain extender introduces nano-silica into the coating molecular chain. The combination of the two enables the car cover to effectively disperse stress, reduce the occurrence of cracks and punctures, and improve its service life. Attached Figure Description

[0042] Figure 1 This is a cross-sectional view of a self-healing paint protection film according to an embodiment of this application.

[0043] Explanation of reference numerals in the attached diagram: 1. Protective film; 2. Self-healing coating; 3. Transparent substrate; 4. Adhesive layer; 5. Release film. Detailed Implementation

[0044] This application discloses a self-healing paint protection film and its preparation method. Unless otherwise specified, all raw materials used in this application are commercially available. The following detailed description, in conjunction with embodiments, further illustrates this application:

[0045] Raw material description: The bio-based polyol is cashew nut shell oil bio-based polyol, model FX-9001LV, purchased from Guangzhou Haoyi New Material Technology Co., Ltd.; perfluorohexyl propylene oxide (CAS No.: 38565-52-5); tetrabutylammonium bromide (CAS No.: 1643-19-2); nano silica with a particle size of 50nm; silane coupling agent model KH-550 (CAS No.: 919-30-2); honokiol (CAS: 528-43-8); diethylenetriamine (CAS No.: 111-40-0); maleimide (CAS No.: 541-59-3); formaldehyde (CAS No.: 5... The ingredients are: 0-00-0), urea (CAS No.: 57-13-6), sodium dodecylbenzenesulfonate (CAS No.: 25155-30-0), transparent substrate is made of TPU, protective film and release film are made of PET, adhesive is acrylic glue, model 720, purchased from Suzhou Qinchuan Electric Co., Ltd., polyisocyanate is toluene diisocyanate (CAS No.: 584-84-9), 4,4'-diaminodiphenyl disulfide (CAS No.: 139-65-1), initiator is azobisisobutyronitrile (CAS No.: 78-67-1), solvent is a mixture of toluene and N,N-dimethylformamide in a volume ratio of 1:1.

[0046] Example 1

[0047] Preparation of fluorinated polyols

[0048] Nitrogen gas was purged into the reactor for 30 minutes. 45.45 g of bio-based polyol was added to the reactor, and 4.55 g of perfluorohexyl propylene oxide was added to the reactor under stirring at 300 rpm. The addition was completed within 2 hours. After the addition was completed, 1 g of tetrabutylammonium bromide was added to the reactor, and the temperature was raised to 100°C. The reactor was stirred and refluxed at 300 rpm for 6 hours. After cooling to 30°C, impurities were removed by vacuum distillation to obtain the product. The product was dissolved in ethyl acetate, and solid impurities were removed by filtration. The solvent was removed by rotary evaporation of the filtrate to obtain the fluorinated polyol.

[0049] Preparation of modified magnolol chain extender

[0050] 1.1 g of nano-silica was dispersed in 10 mL of anhydrous ethanol and sonicated to obtain a nano-silica dispersion. 4.04 g of silane coupling agent was dispersed in 10 mL of deionized water, and the pH was adjusted to 5 with 1 mol / L hydrochloric acid. The mixture was stirred at 200 rpm for 1 h to obtain a hydrolyzed silane coupling agent solution. 4.86 g of magnolol and the hydrolyzed silane coupling agent solution were added to the nano-silica dispersion, and the mixture was stirred at 200 rpm at 80 °C for 1 h. After the reaction, the mixture was washed with deionized water by centrifugation and dried in an oven at 80 °C to obtain a modified magnolol chain extender.

[0051] Preparation of self-healing microcapsules

[0052] A four-necked flask was purged with nitrogen for 30 minutes. 11.11 g of diethylenetriamine was added to the flask, and 8.89 g of maleimide was added to the flask under stirring at 200 rpm. The addition was completed within 1 hour. After the addition was complete, the temperature was raised to 80 °C and the mixture was stirred and refluxed at 300 rpm for 4 hours. After cooling to room temperature, the product was poured into diethyl ether, filtered, and the precipitate was collected. The precipitate was washed with diethyl ether and dried under vacuum at 60 °C to obtain the modified polyamine.

[0053] Modified polyamine was dissolved in anhydrous ethanol to obtain a modified polyamine solution. A 37% (w / w) formaldehyde solution and urea were mixed in a three-necked flask to achieve a formaldehyde to urea mass ratio of 3:4. The pH was adjusted to 9 using a 1 mol / L sodium hydroxide solution, and the mixture was stirred at 300 rpm for 1 h at 80 °C to obtain a urea-formaldehyde resin prepolymer solution. The modified polyamine solution was added to the urea-formaldehyde resin prepolymer solution to achieve a core-to-material ratio of 1:2, and the mixture was stirred at 500 rpm for 20 min to obtain a mixture. Sodium dodecylbenzenesulfonate (2% by mass of the mixture) was added, and the mixture was emulsified at 8000 rpm for 10 min to obtain an emulsion. The pH of the emulsion was adjusted to 3 using a 1 mol / L hydrochloric acid aqueous solution, and the mixture was stirred at 200 rpm for 4 h at 60 °C. After cooling to room temperature, the mixture was filtered to obtain microcapsules. The microcapsules were washed with deionized water until neutral and then dried at 60 °C to obtain self-healing microcapsules.

[0054] Preparation of self-healing paint protection film

[0055] Under nitrogen protection, the temperature was raised to 60℃ and stirred at 200 rpm. 15 g of polyisocyanate was added to 20 g of fluorinated polyol, and the addition was completed within 1 hour. After the addition was completed, the reaction continued for 2 hours to obtain the prepolymer. 5 g of composite chain extender was dissolved in solvent. The mass ratio of 4,4'-diaminodiphenyl disulfide and modified magnolol chain extender in the composite chain extender was 1:2 to obtain a chain extender dispersion. The chain extender dispersion was added to the prepolymer, and the temperature was raised to 80℃ and stirred at 300 rpm for 2 hours to obtain the polymer. 1 g of initiator was dissolved in solvent to obtain an initiator solution, making the total solvent usage 30 g. 10 g of self-healing microcapsules were added to the polymer, and the mixture was stirred at 200 rpm for 30 minutes at 60℃. The initiator solution was added, and the mixture was stirred at 200 rpm for 1 hour. After cooling, the material was discharged to obtain the self-healing coating.

[0056] An adhesive is applied to the surface of a transparent substrate to obtain an adhesive layer. A release film is then applied to the adhesive layer to obtain a semi-finished car cover. A self-healing coating is applied to the side of the semi-finished car cover away from the release film and cured at 100°C for 2 hours to obtain a semi-finished car cover with a self-healing coating. A protective film is then applied to the self-healing coating and cured in a 50°C curing chamber for 2 days to obtain a self-healing invisible car cover.

[0057] Example 2

[0058] Preparation of fluorinated polyols

[0059] Nitrogen gas was purged into the reactor for 30 minutes. 38.46 g of bio-based polyol was added to the reactor, and 11.54 g of perfluorohexyl propylene oxide was added to the reactor under stirring at 300 rpm. The addition was completed within 2 hours. After the addition was completed, 1 g of tetrabutylammonium bromide was added to the reactor, and the temperature was raised to 100°C. The reactor was stirred and refluxed at 300 rpm for 6 hours. After cooling to 30°C, impurities were removed by vacuum distillation to obtain the product. The product was dissolved in ethyl acetate, and solid impurities were removed by filtration. The solvent was removed by rotary evaporation of the filtrate to obtain the fluorinated polyol.

[0060] Preparation of modified magnolol chain extender

[0061] 1.1 g of nano-silica was dispersed in 10 mL of anhydrous ethanol and sonicated to obtain a nano-silica dispersion. 4.04 g of silane coupling agent was dispersed in 10 mL of deionized water, and the pH was adjusted to 5 with 1 mol / L hydrochloric acid. The mixture was stirred at 200 rpm for 1 h to obtain a hydrolyzed silane coupling agent solution. 4.86 g of magnolol and the hydrolyzed silane coupling agent solution were added to the nano-silica dispersion, and the mixture was stirred at 200 rpm at 80 °C for 1 h. After the reaction, the mixture was washed with deionized water by centrifugation and dried in an oven at 80 °C to obtain a modified magnolol chain extender.

[0062] Preparation of self-healing microcapsules

[0063] A four-necked flask was purged with nitrogen for 30 minutes. 10 g of diethylenetriamine was then added to the flask, followed by 10 g of maleimide under stirring at 200 rpm. The addition was completed within 1 hour. After the addition was complete, the temperature was raised to 80 °C and the mixture was stirred and refluxed at 300 rpm for 4 hours. After cooling to room temperature, the product was poured into diethyl ether, filtered, and the precipitate was collected. The precipitate was washed with diethyl ether and then dried under vacuum at 60 °C to obtain the modified polyamine.

[0064] Modified polyamine was dissolved in anhydrous ethanol to obtain a modified polyamine solution. A 37% (w / w) formaldehyde solution and urea were mixed in a three-necked flask to achieve a formaldehyde to urea mass ratio of 3:4. The pH was adjusted to 9 using a 1 mol / L sodium hydroxide solution, and the mixture was stirred at 300 rpm for 1 h at 80 °C to obtain a urea-formaldehyde resin prepolymer solution. The modified polyamine solution was added to the urea-formaldehyde resin prepolymer solution to achieve a core-to-material ratio of 1:2, and the mixture was stirred at 500 rpm for 20 min to obtain a mixture. Sodium dodecylbenzenesulfonate (2% by mass of the mixture) was added, and the mixture was emulsified at 8000 rpm for 10 min to obtain an emulsion. The pH of the emulsion was adjusted to 3 using a 1 mol / L hydrochloric acid aqueous solution, and the mixture was stirred at 200 rpm for 4 h at 60 °C. After cooling to room temperature, the mixture was filtered to obtain microcapsules. The microcapsules were washed with deionized water until neutral and then dried at 60 °C to obtain self-healing microcapsules.

[0065] Preparation of self-healing paint protection film

[0066] Under nitrogen protection, the temperature was raised to 60℃ and stirred at 200 rpm. 30 g of polyisocyanate was added to 40 g of fluorinated polyol within 1 hour. After the addition was complete, the reaction continued for 2 hours to obtain a prepolymer. 10 g of composite chain extender was dissolved in a solvent. The mass ratio of 4,4'-diaminodiphenyl disulfide and modified honokiol chain extender in the composite chain extender was 1:2 to obtain a chain extender dispersion. The chain extender dispersion was added to the prepolymer, and the temperature was raised to 80℃ and stirred at 300 rpm for 2 hours to obtain a polymer. 3 g of initiator was dissolved in a solvent to obtain an initiator solution, making the total solvent usage 50 g. 20 g of self-healing microcapsules were added to the polymer, and the mixture was stirred at 200 rpm for 30 minutes at 60℃. The initiator solution was added, and the mixture was stirred at 200 rpm for 1 hour. After cooling, the material was discharged to obtain a self-healing coating.

[0067] An adhesive is applied to the surface of a transparent substrate to obtain an adhesive layer. A release film is then applied to the adhesive layer to obtain a semi-finished car cover. A self-healing coating is applied to the side of the semi-finished car cover away from the release film and cured at 100°C for 2 hours to obtain a semi-finished car cover with a self-healing coating. A protective film is then applied to the self-healing coating and cured in a 50°C curing chamber for 2 days to obtain a self-healing invisible car cover.

[0068] Example 3

[0069] Preparation of fluorinated polyols

[0070] Nitrogen gas was purged into the reactor for 30 minutes. 41.67 g of bio-based polyol was added to the reactor. Under stirring at 300 rpm, 8.33 g of perfluorohexyl propylene oxide was added to the reactor over 2 hours. After the addition was complete, 1 g of tetrabutylammonium bromide was added to the reactor. The temperature was raised to 100°C, and the mixture was stirred and refluxed at 300 rpm for 6 hours. After cooling to 30°C, impurities were removed by vacuum distillation to obtain the product. The product was dissolved in ethyl acetate, and solid impurities were removed by filtration. The solvent was removed by rotary evaporation of the filtrate to obtain the fluorinated polyol.

[0071] Preparation of modified magnolol chain extender

[0072] 1.1 g of nano-silica was dispersed in 10 mL of anhydrous ethanol and sonicated to obtain a nano-silica dispersion. 4.04 g of silane coupling agent was dispersed in 10 mL of deionized water, and the pH was adjusted to 5 with 1 mol / L hydrochloric acid. The mixture was stirred at 200 rpm for 1 h to obtain a hydrolyzed silane coupling agent solution. 4.86 g of magnolol and the hydrolyzed silane coupling agent solution were added to the nano-silica dispersion, and the mixture was stirred at 200 rpm at 80 °C for 1 h. After the reaction, the mixture was washed with deionized water by centrifugation and dried in an oven at 80 °C to obtain a modified magnolol chain extender.

[0073] Preparation of self-healing microcapsules

[0074] A four-necked flask was purged with nitrogen for 30 minutes. 10.53 g of diethylenetriamine was added to the flask, followed by 9.47 g of maleimide under stirring at 200 rpm. The addition was completed within 1 hour. After the addition was complete, the temperature was raised to 80 °C and the mixture was stirred and refluxed at 300 rpm for 4 hours. After cooling to room temperature, the product was poured into diethyl ether, filtered, and the precipitate was collected. The precipitate was washed with diethyl ether and then dried under vacuum at 60 °C to obtain the modified polyamine.

[0075] Modified polyamine was dissolved in anhydrous ethanol to obtain a modified polyamine solution. A 37% (w / w) formaldehyde solution and urea were mixed in a three-necked flask to achieve a formaldehyde to urea mass ratio of 3:4. The pH was adjusted to 9 using a 1 mol / L sodium hydroxide solution, and the mixture was stirred at 300 rpm for 1 h at 80 °C to obtain a urea-formaldehyde resin prepolymer solution. The modified polyamine solution was added to the urea-formaldehyde resin prepolymer solution to achieve a core-to-material ratio of 1:2, and the mixture was stirred at 500 rpm for 20 min to obtain a mixture. Sodium dodecylbenzenesulfonate (2% by mass of the mixture) was added, and the mixture was emulsified at 8000 rpm for 10 min to obtain an emulsion. The pH of the emulsion was adjusted to 3 using a 1 mol / L hydrochloric acid aqueous solution, and the mixture was stirred at 200 rpm for 4 h at 60 °C. After cooling to room temperature, the mixture was filtered to obtain microcapsules. The microcapsules were washed with deionized water until neutral and then dried at 60 °C to obtain self-healing microcapsules.

[0076] Preparation of self-healing paint protection film

[0077] Under nitrogen protection, the temperature was raised to 60℃ and stirred at 200 rpm. 22.5 g of polyisocyanate was added to 30 g of fluorinated polyol within 1 hour. After the addition was complete, the reaction continued for 2 hours to obtain the prepolymer. 7.5 g of composite chain extender was dissolved in a solvent. The mass ratio of 4,4'-diaminodiphenyl disulfide and modified magnolol chain extender in the composite chain extender was 1:2 to obtain a chain extender dispersion. The chain extender dispersion was added to the prepolymer, and the temperature was raised to 80℃ and stirred at 300 rpm for 2 hours to obtain the polymer. 2 g of initiator was dissolved in a solvent to obtain an initiator solution, making the total solvent usage 40 g. 15 g of self-healing microcapsules were added to the polymer, and the mixture was stirred at 200 rpm for 30 minutes at 60℃. The initiator solution was added, and the mixture was stirred at 200 rpm for 1 hour. After cooling, the material was discharged to obtain the self-healing coating.

[0078] An adhesive is applied to the surface of a transparent substrate to obtain an adhesive layer. A release film is then applied to the adhesive layer to obtain a semi-finished car cover. A self-healing coating is applied to the side of the semi-finished car cover away from the release film and cured at 100°C for 2 hours to obtain a semi-finished car cover with a self-healing coating. A protective film is then applied to the self-healing coating and cured in a 50°C curing chamber for 2 days to obtain a self-healing invisible car cover.

[0079] Example 4

[0080] Example 4 is based on Example 3. The only difference between Example 4 and Example 3 is that the amount of bio-based polyol used in Example 4 is 47.62g and the amount of perfluorohexyl propylene oxide is 2.38g.

[0081] Example 5

[0082] Example 5 is based on Example 3. The only difference between Example 5 and Example 3 is that the amount of bio-based polyol used in Example 5 is 35.71g and the amount of perfluorohexyl propylene oxide used is 14.29g.

[0083] Example 6

[0084] Example 6 is based on Example 3. The only difference between Example 6 and Example 3 is that the modified magnolol chain extender is replaced with magnolol in Example 6.

[0085] Example 7

[0086] Example 7 is based on Example 3. The only difference between Example 7 and Example 3 is that in Example 7, the amount of diethylenetriamine is 12.5g and the amount of maleimide is 7.5g.

[0087] Example 8

[0088] Example 8 is based on Example 3. The only difference between Example 8 and Example 3 is that in Example 8, the amount of diethylenetriamine is 9.09g and the amount of maleimide is 10.91g.

[0089] Example 9

[0090] Example 9 is based on Example 3. The only difference between Example 9 and Example 3 is that the modified polyamine is replaced with diethylenetriamine in Example 9.

[0091] Comparative Example 1

[0092] Comparative Example 1 is based on Example 3. The only difference between Comparative Example 1 and Example 3 is that the fluorinated polyol in Comparative Example 1 is replaced with a bio-based polyol.

[0093] Comparative Example 2

[0094] Comparative Example 2 is based on Example 3. The only difference between Comparative Example 2 and Example 3 is that the composite chain extender in Comparative Example 2 is replaced with 4,4'-diaminodiphenyl disulfide.

[0095] Comparative Example 3

[0096] Comparative Example 3 is based on Example 3. The only difference between Comparative Example 3 and Example 3 is that self-healing microcapsules are not added in Comparative Example 3.

[0097] Performance testing

[0098] (1) Self-healing performance test: At 60℃, a 5μm deep scratch was made on the sample using a nano-scratch instrument, and the recovery time was recorded. Each sample was tested three times, and the average value was taken after measurement. The results are recorded in Table 1.

[0099] (4) Select GB1040-79 Plastics Tensile Test Method and GB / T 1865-2009 Paints and Varnishes Artificial Climate Aging and Artificial Radiation Exposure (Filtered Xenon Arc Radiation) as standards to test the tensile strength of the specimens before and after aging. Three samples are prepared for each specimen, and the average value is taken after measurement. The test results are recorded in Table 1.

[0100] (2) Weather resistance test: After peeling off the protective layer and release layer, attach the sample to the test steel plate and age it under a UVA-340 ultraviolet lamp for 1000 hours. Take it out and observe it to evaluate the fastness level. The results are recorded in Table 1.

[0101] (3) Select GB / T 37841-2019 Test Method for Puncture Resistance of Plastic Films and Sheets as the standard, prepare 5 25mm*25mm samples, select 4 points around the sample to test the thickness, calculate the average thickness, carry out the puncture test at a speed of 100mm / min, calculate the puncture strength, take the average value after measurement, and record the results in Table 1.

[0102] Table 1. Test results of the car cover's self-healing performance, weather resistance, tensile strength, and puncture resistance.

[0103]

[0104]

[0105] As shown in Table 1, the self-healing time of Examples 1-3 is less than 8.56s, the tensile strength is greater than 19.47MPa, the tensile strength after aging is greater than 15.37MPa, and the puncture strength is greater than 75.68N / mm. This shows that the self-healing invisible car wrap prepared in this application has good self-healing performance, weather resistance, tensile strength and puncture resistance.

[0106] As shown in Table 1, the only difference between Examples 4-5, Comparative Example 1, and Example 3 is that the mass ratio of bio-based polyol to perfluorohexyl propylene oxide in Example 4 is 1:0.05, the mass ratio of bio-based polyol to perfluorohexyl propylene oxide in Example 5 is 1:0.4, and Comparative Example 1 replaces the fluorinated polyol with a bio-based polyol. Compared with Example 3, the performance of Examples 4-5, Comparative Example 1, and Example 3 is somewhat reduced. This is because if the component ratio of the fluorinated polyol is disrupted, the introduction of too few fluorine atoms has limited effect on performance improvement, while too many fluorine atoms will affect the stability of the material, leading to abnormal interactions between components and reducing the material's performance. If fluorine is not introduced, the performance will further decline, resulting in a decrease in self-healing properties, weather resistance, tensile strength, and puncture resistance.

[0107] As shown in Table 1, the only difference between Example 6, Comparative Example 2, and Example 3 is that in Example 6, the modified honokiol chain extender was replaced with honokiol, and in Comparative Example 2, the composite chain extender was replaced with 4,4'-diaminodiphenyl disulfide. Compared with Example 3, the self-healing performance, weather resistance, tensile strength, and puncture resistance of Examples 6, Comparative Example 2, and Example 3 decreased. This is because replacing the modified honokiol chain extender with honokiol lacks the introduction of nano-silica, resulting in a decrease in physical reinforcement. At the same time, the antioxidant performance lacks the synergistic enhancement of nano-silica, leading to poorer weather resistance. Consequently, the self-healing performance, weather resistance, tensile strength, and puncture resistance all decreased. If the composite chain extender is replaced with 4,4'-diaminodiphenyl disulfide, the synergistic effect between the components will be further affected, resulting in a further decrease in performance.

[0108] As shown in Table 1, the differences between Examples 7-9, Comparative Example 3, and Example 3 are only as follows: In Example 7, the mass ratio of diethylenetriamine to maleimide is 1:0.6; in Example 8, the mass ratio of diethylenetriamine to maleimide is 1:1.2; in Example 9, the modified polyamine is replaced with diethylenetriamine; and in Comparative Example 3, no self-healing microcapsules are added. Compared with Example 3, Examples 7-9, Comparative Example 3, and Example 3 all show a decrease in self-healing performance, weather resistance, tensile strength, and puncture resistance. This is because the composition ratio of the modified polyamine is disrupted. Too much or too little maleimide will affect the stability and reactivity of the modified polyamine, thus affecting the self-healing performance. Replacing the modified polyamine with diethylenetriamine, without modification treatment, will further decrease the stability and reactivity of diethylenetriamine. And without adding self-healing microcapsules, the self-healing performance will be directly affected, and the self-healing performance of the material will decrease significantly.

[0109] This specific embodiment is merely an explanation of this application and is not intended to limit it. Based on the above description, those skilled in the art can make various changes and modifications without departing from the technical concept of this application. The technical scope of this application is not limited to the contents of the specification but must be determined according to the scope of the claims.

Claims

1. A self-repairing paint protection film, characterized in that: The product comprises, in sequence, a protective film, a self-healing coating, a transparent substrate, an adhesive layer, and a release film. The self-healing coating is obtained by applying a self-healing paint, and the raw materials for preparing the self-healing paint include the following components in parts by weight: 20-40 parts of fluorinated polyols 15-30 parts of polyisocyanate 5-10 parts of compound chain extender 10-20 doses of self-repairing microcapsules 1-3 parts of initiator Solvent 30-50 parts; The composite chain extender includes 4,4'-diaminodiphenyl disulfide and modified magnolol chain extender; The raw materials for preparing the modified magnolol chain extender include magnolol bulk, silane coupling agent and nano-silica; The modified magnolol chain extender is prepared using the following steps: Nano-silica was dispersed in anhydrous ethanol and sonicated to obtain a nano-silica dispersion. A silane coupling agent was dispersed in water, the pH was adjusted to acidic, and the mixture was stirred to obtain a hydrolyzed silane coupling agent solution. Magnolol and the hydrolyzed silane coupling agent solution were added to the nano-silica dispersion, and the mixture was heated and stirred to react. After the reaction was completed, the mixture was centrifuged, washed, and dried to obtain a modified magnolol chain extender.

2. The self-repairing vehicle camouflage of claim 1, wherein: The raw materials for preparing the fluorinated polyol include bio-based polyol and perfluorohexyl propylene oxide.

3. The self-repairing vehicle camouflage paint of claim 2, wherein: The mass ratio of the bio-based polyol to perfluorohexyl propylene oxide is 1:(0.1-0.3).

4. The self-repairing vehicle camouflage of claim 1, wherein: The raw materials for preparing the self-healing microcapsules include modified polyamines and urea-formaldehyde resin.

5. The self-repairing vehicle camouflage paint of claim 4, wherein: The raw materials for preparing the modified polyamine include diethylenetriamine and maleimide.

6. The self-repairing vehicle camouflage paint of claim 5, wherein: The mass ratio of diethylenetriamine to maleimide is 1:(0.8-1).

7. A method for preparing the self-repairing car cover according to any one of claims 1-6, characterized in that: Includes the following steps: Under a neutral gas atmosphere, polyisocyanate was added to a fluorinated polyol while heating and stirring. After reaction, a prepolymer was obtained. A composite chain extender was dissolved in a solvent to obtain a chain extender dispersion. The chain extender dispersion was added to the prepolymer, and the mixture was heated and stirred to obtain a polymer. An initiator was dissolved in a solvent to obtain an initiator solution. Self-healing microcapsules were added to the polymer, and the mixture was heated and stirred to react. Then, the initiator solution was added, and the mixture was heated and stirred to react. After cooling, the mixture was discharged to obtain a self-healing coating. An adhesive is applied to the surface of a transparent substrate to obtain an adhesive layer. A release film is then applied to the adhesive layer to obtain a semi-finished car wrap. A self-healing coating is applied to the side of the semi-finished car wrap away from the release film and cured by heating to obtain a semi-finished car wrap with a self-healing coating. A protective film is then applied to the self-healing coating and allowed to mature to obtain a self-healing invisible car wrap.

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