Scratch-resistant automotive window film and method of making the same

Abstract

The present application relates to a kind of scratch-resistant car film and its preparation method, belong to composite film material technical field.The car film is multilayer composite structure, from inside to outside, it includes pressure sensitive adhesive layer, TPU base film, functional coating and release film in sequence.Innovation lies in, the functional coating is formed by the slurry solidification including specific self-repairing scratch-resistant agent, the scratch-resistant agent is formed by the reaction of terminal hydroxyl silicone oil and methyl vinyl dichlorosilane to form alkenyl intermediate, then through mercaptoacetaldehyde click addition introduction aldehyde group, finally with amine phenyl POSS is prepared by mannich reaction, to build "POSS rigid core-dynamic imine bond-flexible thioether chain" composite structure in organosilicon side chain.The structure makes coating simultaneously have excellent scratch resistance, high transmittance and efficient heat stimulus response self-repairing ability.

Description

Technical Field

[0001] This invention belongs to the field of composite film material technology, specifically, it relates to a scratch-resistant automotive film and its preparation method. Background Technology

[0002] Car wrap (also known as paint protection film) is a high-performance transparent film applied to the car's paint surface. Its main function is to isolate the paint from external environmental factors, preventing damage such as stone impacts, scratches from hard objects, acid rain corrosion, UV aging, and scorching from daily car washes, thus maintaining the original gloss and integrity of the vehicle's paint for a long time. With the upgrading of car consumption and the increasing awareness of car maintenance among car owners, the market demand for high-performance paint protection films continues to grow.

[0003] Early automotive protective films were mostly single-layer PVC or PU films. While they offered some protection, they generally suffered from poor weather resistance, yellowing, insufficient flexibility leading to difficulties in edge application, and a lack of self-repair capabilities after damage. To overcome these shortcomings, modern high-end automotive protective films typically employ multi-layer composite structures. A typical composite film, extending outwards from the paint-coated side, mainly includes a pressure-sensitive adhesive layer (base layer), a base film, a functional coating, and a release film. The outermost functional coating is in direct contact with the external environment, and its performance directly determines the film's lifespan and surface quality.

[0004] Among numerous functional coating materials, silicone coatings are considered highly promising automotive exterior protective materials due to their excellent resistance to high and low temperatures, superior UV aging resistance, outstanding hydrophobic and oleophobic properties, and good tolerance to environmental factors such as acids, alkalis, and ozone. However, pure silicone coating materials are relatively soft, resulting in poor scratch resistance. In daily use, they are easily scratched by hard objects such as gravel and branches, affecting both aesthetics and protective effect.

[0005] To address the issue of insufficient scratch resistance in silicone coatings, existing technologies have proposed the following improvement solutions: (1) Filler blending modification and reinforcement: This is the most direct traditional method, which is to add rigid nanoparticles (such as silica, alumina, silicon carbide, etc.) or fibers to the silicone resin for composite. These rigid fillers can significantly improve the hardness, modulus and wear resistance of the coating. However, the drawbacks of this method are also significant: the addition of fillers often leads to increased brittleness and decreased flexibility of the coating, resulting in poor adhesion of the film when applied to curved surfaces and easy edge lifting; in addition, if the filler is not evenly dispersed or the particle size is not properly controlled, it will severely scatter visible light, resulting in decreased coating transparency and increased haze, affecting the appearance of the film. Interface defects between rigid particles and the silicone matrix may also become stress concentration points, accelerating coating cracking.

[0006] (2) Increasing crosslinking density: By increasing the functionality of the silicone prepolymer or using a higher amount of crosslinking agent, a denser three-dimensional network structure is formed, thereby improving the stiffness and hardness of the coating. For example, some highly crosslinked silicone hard coatings. Although this method can improve scratch resistance to some extent, the cost is a sharp increase in the elastic modulus of the coating and a significant decrease in the elongation at break, making the film stiff and losing the flexibility and impact resistance necessary for it as a car film, making it prone to brittle fracture under large external forces. Summary of the Invention

[0007] In order to solve the technical problems mentioned in the background art, the purpose of this invention is to provide a scratch-resistant automotive film and its preparation method.

[0008] The objective of this invention can be achieved through the following technical solutions: A scratch-resistant automotive film is a multi-layer composite film, comprising, from the paint-coating side outwards: a pressure-sensitive adhesive layer, a TPU base film, a functional coating, and a release film.

[0009] Specifically, the functional coating slurry comprises, by weight, 100 parts liquid silicone rubber, 4.8-6.5 parts self-healing anti-scratch agent, 3.5-4.5 parts reactive diluent, 0.15-0.2 parts leveling agent, and 0.3-0.4 parts defoamer.

[0010] The preparation method of scratch-resistant automotive film is as follows: Step S1: Premix the self-healing anti-scratch agent, reactive diluent, leveling agent and defoamer, then add them to the liquid silicone rubber and mix well to make a slurry; Step S2: The slurry is evenly coated onto the surface of the TPU base film, and then the film is dried and cured in stages to form a functional coating on the TPU base film. Then, a pressure-sensitive adhesive layer is coated on the bottom layer of the TPU base film, and a release film is attached to the surface of the functional coating to obtain the automotive film.

[0011] Preferably, the coating amount of the functional coating slurry is 7.5-9.2 g / m². 2 .

[0012] Preferably, the process parameters for segmented drying and curing are set as follows: the temperature of the first segment is 50-60℃ and the time is 8-10 min; the temperature of the second segment is 82-88℃ and the time is 15-20 min.

[0013] Preferably, both the defoamer and the leveling agent are silicone preparations.

[0014] The self-healing anti-scratch agent is prepared by the following method: Step A1: Mix the hydroxyl-terminated silicone oil and anhydrous tetrahydrofuran, cool in a dry nitrogen atmosphere and ice-water bath, slowly add methylvinyldichlorosilane while controlling the temperature above 10°C, then add triethylamine and heat to 40-50°C to continue the reaction for 2.5-4 hours. After the reaction is complete, filter, rotary evaporate to recover the tetrahydrofuran, wash the substrate with water, remove the aqueous phase and dry to obtain the homo-alkenylated silicon intermediate.

[0015] Furthermore, the hydroxyl content of the hydroxyl-terminated silicone oil, and the ratio of methyl vinyl dichlorosilane, triethylamine, and anhydrous tetrahydrofuran are 0.1 mol: 45-50 mmol: 15-20 mL: 70-100 mL. The methyl vinyl dichlorosilane reacts with the hydroxyl-terminated silicone oil to form a macromolecular organosilicon chain, while simultaneously introducing vinyl groups uniformly into the side chains.

[0016] Step A2: Mix the homo-alkenylated silicon intermediate, mercaptoacetaldehyde and anhydrous ethanol, purge with nitrogen to remove oxygen, then add benzoin dimethyl ether and mix. Simultaneously, irradiate with an ultraviolet light source and stir the reaction for 6-8 hours. After the reaction is complete, reduce the pressure and rotary evaporate to recover the ethanol to obtain the aldehyde-modified matrix.

[0017] Furthermore, the ratio of homo-alkenylated silicon intermediate, mercaptoacetaldehyde, benzoin dimethyl ether, and anhydrous ethanol is 25g: 50-60mmol: 25-35mg: 120-150mL. Mercaptoacetaldehyde undergoes an addition reaction with the side-chain vinyl group of the homo-alkenylated silicon intermediate to form a side-chain aldehyde modification.

[0018] Step A3: Premix amine phenyl POSS and dimethylformamide, then add aldehyde-modified matrix and mix well. Under nitrogen protection, heat to 80-100℃, add p-toluenesulfonic acid and stir for 12-16 hours. After the reaction is completed, add deionized water and wash. After separating the aqueous phase, vacuum dry to obtain the self-healing anti-scratch agent.

[0019] Furthermore, the ratio of aldehyde-modified matrix, aminephenyl POSS, p-toluenesulfonic acid, and dimethylformamide is 25g:10-15mmol:0.1-0.13g:270-330mL. Aminephenyl POSS reacts with the side chain aldehyde group of the aldehyde-modified matrix to form an imine-based micro-crosslinked product.

[0020] The beneficial effects of this invention are: This invention provides a scratch-resistant automotive film and its preparation method. Its core innovation lies in the design and synthesis of a self-healing scratch-resistant agent for co-modification of the coating, systematically resolving the inherent contradiction between coating hardness, toughness, transparency, and self-healing performance. Compared with existing technologies, this invention achieves the following significant advancements: First, this invention has fundamental advantages in material compatibility and structural uniformity. The self-healing anti-scratch agent has a linear polydimethylsiloxane as its main chain, and its chemical nature is highly similar to that of the coating matrix (liquid silicone rubber), ensuring that it can achieve uniform dispersion at the molecular level before curing, avoiding light scattering and stress concentration caused by phase separation. In contrast, existing technologies often directly embed dynamic covalent bonds such as disulfide bonds and imine bonds or large organic segments into the organosilicon main chain to introduce self-healing capabilities. This main chain modification strategy inevitably destroys the inherent Si-O-Si bond continuity and regularity of the polysiloxane main chain, leading to a significant deterioration in coating performance; that is, the initial protective performance is sacrificed in order to obtain repair capabilities.

[0021] Secondly, regarding the mechanism for improving scratch resistance, this invention achieves a synergistic effect of "strengthening" and "toughening." The uniformly dispersed POSS rigid cage-like nanostructure serves as an efficient stress transfer and load-bearing point, effectively enhancing the surface hardness of the coating and its resistance to plastic deformation. Crucially, the POSS is anchored to the organosilicon network via dynamic imine "connecting arms" containing flexible sulfide bonds. When subjected to scratch stress, the slight deformation of the POSS itself, along with the rotation and buckling of the sulfide bonds, efficiently absorbs and dissipates impact energy, buffering and dispersing localized stress to the surrounding elastic matrix. This maintains the extremely high flexibility of the organosilicon-based coating, fundamentally overcoming the coating embrittlement problem caused by traditional filler reinforcement or increased crosslinking.

[0022] Of particular note is the intelligent guidance of damage generation and repair pathways in this invention. When the external force exceeds the buffer limit, the relatively rigid POSS (Position of Stress Separation) fractures due to stress concentration. This "selective sacrifice" mechanism controls the damage at a preset reversible site, rather than irreversibly destroying the continuous organosilicon backbone. The active end groups generated after fracture can rapidly reconnect the broken bonds through a reversible imine exchange reaction, thanks to the extremely high degree of freedom of movement provided by the sulfide chain. In contrast, existing technologies introduce random dynamic bonds into the organosilicon backbone, resulting in uncontrollable fracture sites and poor chain segment mobility after fracture, leading to low repair efficiency and difficulty in effectively repairing deep scratches.

[0023] In summary, this invention successfully integrates the scratch resistance and intelligent repair capabilities of high-modulus POSS nanoreinforcement with the intrinsic flexibility and high transparency of the organosilicon matrix. The resulting coating not only achieves excellent optical properties such as high light transmittance and low haze, but also fundamentally enhances the material's initial scratch resistance and post-damage self-healing properties, providing a novel solution for the development of high-end automotive paint protection films and other precision flexible protective materials. Detailed Implementation

[0024] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0025] Example 1: Preparation of scratch-resistant automotive film. The specific implementation process is as follows: I. Preparation of Self-Healing Anti-Scratch Agent Step A1: Add hydroxyl-terminated silicone oil and anhydrous tetrahydrofuran to the mixture and stir until homogeneous. Purge with dried nitrogen until a stable gas flow is observed. Then, cool the reaction system in an ice-water bath until the temperature is below 5°C. Slowly add methylvinyl dichlorosilane, ensuring the reaction system temperature does not exceed 10°C. After complete addition, heat the mixture at 40°C and stir for 4 hours. During the reaction, the hydroxyl-terminated silicone oil is selected from XL2001 type low molecular weight raw material with a hydroxyl content of 9.5%. The ratio of hydroxyl content of the hydroxyl-terminated silicone oil, methylvinyl dichlorosilane, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 50 mmol: 15 mL: 70 mL. After the reaction is complete, filter the mixture and recover the tetrahydrofuran by rotary evaporation. Wash the substrate with water to remove the aqueous phase and then dry to obtain a homo-alkenylated silicon intermediate.

[0026] Step A2: Take the homo-alkenylated silicon intermediate, mercaptoacetaldehyde and anhydrous ethanol, add them and stir to mix well. Purge with nitrogen to remove oxygen, then add benzoin dimethyl ether and mix. Irradiate with a 100W 365nm ultraviolet lamp while stirring for 8 hours. During the reaction, the ratio of homo-alkenylated silicon intermediate, mercaptoacetaldehyde, benzoin dimethyl ether and anhydrous ethanol is 25g:50mmol:25mg:120mL. After the reaction is completed, reduce the pressure and rotary evaporate to recover the ethanol to obtain the aldehyde-modified matrix.

[0027] Step A3: Take amine phenyl POSS and dimethylformamide, add them to the mixture and stir to premix. Then add the aldehyde-modified matrix and mix well. Under nitrogen protection, heat to 80°C and add p-toluenesulfonic acid and stir to react for 16 hours. During the reaction, the ratio of aldehyde-modified matrix, amine phenyl POSS, p-toluenesulfonic acid and dimethylformamide is 25g:10mmol:0.1g:270mL. After the reaction is completed, add deionized water and wash. After separating the aqueous phase, vacuum dry to obtain the self-healing anti-scratch agent.

[0028] II. Preparation of Scratch-Resistant Automotive Film Step S1: Prepare the ingredients according to the following weight proportions: 100 parts liquid silicone rubber, using BD-653 type two-component raw material; 4.8 parts self-healing anti-scratch agent, which is self-made in this embodiment; 3.5 parts reactive diluent, using IOTA 218 type low viscosity vinyl silicone oil; 0.15 parts leveling agent, using BD-1400 type silicone leveling agent; 0.3 parts defoamer, using BD-303 type silicone defoamer. The self-healing anti-scratch agent and reactive diluent are mixed and diluted, then leveling agent and defoamer are added and premixed. Then, the two-component liquid silicone rubber is slowly added and mixed evenly while stirring to make a slurry.

[0029] Step S2: Mix the prepared slurry according to 7.5 g / m 2 The coating is evenly applied to the surface of the TPU base film, and then sent to a tunnel dryer for segmented drying and curing. The curing process has two stages: the first stage is at a temperature of 50°C for 8 minutes, and the second stage is at a temperature of 82°C for 15 minutes. After the slurry is cured, a functional coating is formed on the surface. Then, a pressure-sensitive adhesive layer is coated on the bottom layer of the TPU base film, and a release film is attached to the surface of the functional coating to obtain the automotive film.

[0030] Example 2: Preparation of scratch-resistant automotive film, the specific implementation process is as follows: I. Preparation of Self-Healing Anti-Scratch Agent Step A1: Add hydroxyl-terminated silicone oil and anhydrous tetrahydrofuran and stir until well mixed. Purge with dried nitrogen until a stable gas flow is observed. Then cool the reaction system in an ice-water bath until the temperature is below 5°C. Slowly add methylvinyl dichlorosilane, ensuring the reaction system temperature does not exceed 10°C. After complete addition, heat the mixture at 45°C and stir for 3.2 hours. During the reaction, the hydroxyl-terminated silicone oil is selected from XL2001 type low molecular weight raw material with a hydroxyl content of 9.5%. The ratio of hydroxyl content of the hydroxyl-terminated silicone oil, methylvinyl dichlorosilane, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 50 mmol: 18 mL: 90 mL. After the reaction is complete, filter the mixture and recover the tetrahydrofuran by rotary evaporation. Wash the substrate with water to remove the aqueous phase and then dry to obtain a homo-alkenylated silicon intermediate.

[0031] Step A2: Take the homo-alkenylated silicon intermediate, mercaptoacetaldehyde and anhydrous ethanol, add them and stir to mix well. Purge with nitrogen to remove oxygen, then add benzoin dimethyl ether and mix. Irradiate with a 100W 365nm ultraviolet lamp while stirring for 7.5h. During the reaction, the ratio of homo-alkenylated silicon intermediate, mercaptoacetaldehyde, benzoin dimethyl ether and anhydrous ethanol is 25g:55mmol:35mg:140mL. After the reaction is completed, reduce the pressure and rotary evaporate to recover the ethanol to obtain the aldehyde-modified matrix.

[0032] Step A3: Take amine phenyl POSS and dimethylformamide, add them to the mixture and stir to premix. Then add the aldehyde-modified matrix and mix well. Under nitrogen protection, heat to 90°C and add p-toluenesulfonic acid and stir to react for 15 hours. During the reaction, the ratio of aldehyde-modified matrix, amine phenyl POSS, p-toluenesulfonic acid and dimethylformamide is 25g:12mmol:0.11g:300mL. After the reaction is completed, add deionized water and wash. After separating the aqueous phase, vacuum dry to obtain the self-healing anti-scratch agent.

[0033] II. Preparation of Scratch-Resistant Automotive Film Step S1: Prepare the ingredients according to the following weight proportions: 100 parts liquid silicone rubber, using BD-653 type two-component raw material; 5.3 parts self-healing anti-scratch agent, which is self-made in this embodiment; 3.9 parts reactive diluent, using IOTA 218 type low viscosity vinyl silicone oil; 0.17 parts leveling agent, using BD-1400 type silicone leveling agent; 0.35 parts defoamer, using BD-303 type silicone defoamer. The self-healing anti-scratch agent and reactive diluent are mixed and diluted, then leveling agent and defoamer are added and premixed. Then, the two-component liquid silicone rubber is slowly added and mixed evenly while stirring to make a slurry.

[0034] Step S2: Mix the prepared slurry according to 8.0 g / m 2 The coating is evenly applied to the surface of the TPU base film, and then sent to a tunnel dryer for segmented drying and curing. The curing process has two stages: the first stage is at a temperature of 55°C for 10 minutes, and the second stage is at a temperature of 85°C for 17 minutes. After the slurry is cured, a functional coating is formed on the surface. Then, a pressure-sensitive adhesive layer is coated on the bottom layer of the TPU base film, and a release film is attached to the surface of the functional coating to obtain the automotive film.

[0035] Example 3: Preparation of scratch-resistant automotive film, the specific implementation process is as follows: I. Preparation of Self-Healing Anti-Scratch Agent Step A1: Add hydroxyl-terminated silicone oil and anhydrous tetrahydrofuran and stir until well mixed. Purge with dried nitrogen until a stable gas flow is observed. Then cool the reaction system in an ice-water bath until the temperature is below 5°C. Slowly add methylvinyl dichlorosilane, ensuring the reaction system temperature does not exceed 10°C. After complete addition, heat the system at 50°C and stir for 2.5 hours. During the reaction, the hydroxyl-terminated silicone oil is selected from XL2001 type low molecular weight raw material with a hydroxyl content of 9.5%. The ratio of hydroxyl content of the hydroxyl-terminated silicone oil, methylvinyl dichlorosilane, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 45 mmol: 20 mL: 100 mL. After the reaction is complete, filter the mixture and recover the tetrahydrofuran by rotary evaporation. Wash the substrate with water to remove the aqueous phase and then dry to obtain a homo-alkenylated silicon intermediate.

[0036] Step A2: Take the homo-alkenylated silicon intermediate, mercaptoacetaldehyde and anhydrous ethanol, add them and stir to mix well. Purge with nitrogen to remove oxygen, then add benzoin dimethyl ether and mix. Irradiate with a 100W 365nm ultraviolet lamp while stirring for 6 hours. During the reaction, the ratio of homo-alkenylated silicon intermediate, mercaptoacetaldehyde, benzoin dimethyl ether and anhydrous ethanol is 25g:60mmol:35mg:150mL. After the reaction is completed, reduce the pressure and rotary evaporate to recover the ethanol to obtain the aldehyde-modified matrix.

[0037] Step A3: Take amine phenyl POSS and dimethylformamide, add them to the mixture and stir to premix. Then add the aldehyde-modified matrix and mix well. Under nitrogen protection, heat to 100℃ and add p-toluenesulfonic acid and stir to react for 12 hours. During the reaction, the ratio of aldehyde-modified matrix, amine phenyl POSS, p-toluenesulfonic acid and dimethylformamide is 25g:15mmol:0.13g:330mL. After the reaction is completed, add deionized water and wash. After separating the aqueous phase, vacuum dry to obtain the self-healing anti-scratch agent.

[0038] II. Preparation of Scratch-Resistant Automotive Film Step S1: Prepare the ingredients according to the following weight proportions: 100 parts liquid silicone rubber, using BD-653 type two-component raw material; 6.5 parts self-healing anti-scratch agent, which is self-made in this embodiment; 4.5 parts reactive diluent, using IOTA 218 type low viscosity vinyl silicone oil; 0.2 parts leveling agent, using BD-1400 type silicone leveling agent; 0.4 parts defoamer, using BD-303 type silicone defoamer. The self-healing anti-scratch agent and reactive diluent are mixed and diluted, then leveling agent and defoamer are added and premixed. Then, the two-component liquid silicone rubber is slowly added and mixed evenly while stirring to make a slurry.

[0039] Step S2: Mix the prepared slurry according to 9.2 g / m 2 The coating is evenly applied to the surface of the TPU base film, and then sent to a tunnel dryer for segmented drying and curing. The curing process has two stages: the first stage is at a temperature of 60°C for 10 minutes, and the second stage is at a temperature of 88°C for 20 minutes. After the slurry is cured, a functional coating is formed on the surface. Then, a pressure-sensitive adhesive layer is coated on the bottom layer of the TPU base film, and a release film is attached to the surface of the functional coating to obtain the automotive film.

[0040] Example 4: Preparation of scratch-resistant automotive film. The specific implementation process is as follows: I. Preparation of Self-Healing Anti-Scratch Agent Step A1: Add hydroxyl-terminated silicone oil and anhydrous tetrahydrofuran and stir until well mixed. Purge with dried nitrogen until a stable gas flow is observed. Then cool the reaction system in an ice-water bath until the temperature is below 5°C. Slowly add methylvinyl dichlorosilane, ensuring the reaction system temperature does not exceed 10°C. After complete addition, heat the mixture at 45°C and stir for 3 hours. During the reaction, the hydroxyl-terminated silicone oil is selected from XL2001 type low molecular weight raw material with a hydroxyl content of 9.5%. The ratio of hydroxyl content of the hydroxyl-terminated silicone oil, methylvinyl dichlorosilane, triethylamine, and anhydrous tetrahydrofuran is 0.1 mol: 50 mmol: 20 mL: 100 mL. After the reaction is complete, filter the mixture and recover the tetrahydrofuran by rotary evaporation. Wash the substrate with water to remove the aqueous phase and then dry to obtain a homo-alkenylated silicon intermediate.

[0041] Step A2: Take the homo-alkenylated silicon intermediate, mercaptoacetaldehyde and anhydrous ethanol, add them and stir to mix well. Purge with nitrogen to remove oxygen, then add benzoin dimethyl ether and mix. Irradiate with a 100W 365nm ultraviolet lamp while stirring for 6.5h. During the reaction, the ratio of homo-alkenylated silicon intermediate, mercaptoacetaldehyde, benzoin dimethyl ether and anhydrous ethanol is 25g:55mmol:30mg:120mL. After the reaction is completed, reduce the pressure and rotary evaporate to recover the ethanol to obtain the aldehyde-modified matrix.

[0042] Step A3: Take amine phenyl POSS and dimethylformamide, add them to the mixture and stir to premix. Then add the aldehyde-modified matrix and mix well. Under nitrogen protection, heat to 90°C and add p-toluenesulfonic acid and stir to react for 14 hours. During the reaction, the ratio of aldehyde-modified matrix, amine phenyl POSS, p-toluenesulfonic acid and dimethylformamide is 25g:14mmol:0.12g:310mL. After the reaction is completed, add deionized water and wash. After separating the aqueous phase, vacuum dry to obtain the self-healing anti-scratch agent.

[0043] II. Preparation of Scratch-Resistant Automotive Film Step S1: Prepare the ingredients according to the following weight proportions: 100 parts liquid silicone rubber, using BD-653 type two-component raw material; 5.7 parts self-healing anti-scratch agent, which is self-made in this embodiment; 4.1 parts reactive diluent, using IOTA 218 type low viscosity vinyl silicone oil; 0.18 parts leveling agent, using BD-1400 type silicone leveling agent; 0.35 parts defoamer, using BD-303 type silicone defoamer. The self-healing anti-scratch agent and reactive diluent are mixed and diluted, then leveling agent and defoamer are added and premixed. Then, the two-component liquid silicone rubber is slowly added and mixed evenly while stirring to make a slurry.

[0044] Step S2: Mix the prepared slurry according to 8.4 g / m 2The coating is evenly applied to the surface of the TPU base film, and then sent to a tunnel dryer for segmented drying and curing. The curing process has two stages: the first stage is at a temperature of 55°C for 10 minutes, and the second stage is at a temperature of 88°C for 17 minutes. After the slurry is cured, a functional coating is formed on the surface. Then, a pressure-sensitive adhesive layer is coated on the bottom layer of the TPU base film, and a release film is attached to the surface of the functional coating to obtain the automotive film.

[0045] Comparative Example 1 follows the same implementation process as Example 3, but without adding self-healing anti-scratch agent to the slurry, and instead adding an equal amount of Aerosil® R812 surface-modified fumed silica. The rest of the implementation process is exactly the same.

[0046] Comparative Example 2 follows the same implementation process as Example 3, but without adding a self-healing anti-scratch agent to the slurry. The weight ratio of components A and B of the liquid silicone rubber is adjusted to 4:6. 4.5 parts of IOTA VM-26 vinyl silicone oil are added as a crosslinking material. The rest of the implementation process is exactly the same.

[0047] Scratch resistance testing was conducted on samples taken from the above-mentioned coating film, specifically according to SAE J400 standard. A gravel impact tester was used, with 500g of gravel (2-4mm in diameter) impacting the film surface at 0.5MPa pressure. The surface scratch density and depth were observed and evaluated after impact. Following ASTM D1044-24 standard, a CS-10 grinding wheel was used with a 500g load, rotating 1000 revolutions, and the haze increase rate was measured. Standard scratches were created on the coating surface using a diamond cone tip (100g load) of a microhardness tester. The initial width and depth of the scratches were measured using a laser confocal microscope. Subsequently, the samples were placed in an environment of 40℃ and 90%RH for 72 hours to accelerate self-healing. After treatment, the remaining width and depth of the scratches were measured again. The width repair rate was calculated as (initial width - remaining width) / initial width × 100%, and the depth repair rate was calculated similarly. Specific test results are shown in Table 1. Table 1 Example 1 Noticeable fine lines 8.3 74.6 58.2 Example 2 Noticeable fine lines 6.5 80.9 62.5 Example 3 Fine lines 5.2 85.2 69.4 Example 4 Fine lines 5.9 87.5 70.6 Comparative Example 1 Noticeable fine lines 12.7 -6.1 -8.8 Comparative Example 2 Noticeable fine lines 9.5 2.4 1.7 As shown in Table 1, all the above samples showed surface scratches under gravel impact. Among them, Examples 3 and 4 only showed slight fine lines. In the wear and scratch test, the haze increase rate of the examples was significantly lower than that of the comparative examples, indicating that the examples were less likely to form scratches under mild scratch conditions. In the repair test, the comparative examples did not show any statistically significant repair indicators, and Comparative Example 1 showed visible scratch expansion. This may be due to the high stress formed by the silica filler, which was slowly released after the scratch.

[0048] To verify the effect of the functional coating on the automotive film, the coating was prepared and relevant tests were conducted. Specifically, following the method in the above embodiments, the slurry was coated onto the surface of the fluoro substrate and cured thoroughly. After complete curing, the coating was demolded and left to stand for 24 hours. Adhesion tests were conducted on samples of the functional coatings. Referring to ASTM D4145-10, the minimum bending radius at which the functional coating did not exhibit visible whitening or cracking was observed. Referring to ASTM D1003-21, transmittance and haze at 550 nm wavelength were measured. Referring to ASTM D523-14, gloss at 60° was tested. Specific test results are shown in Table 2. Table 2 Example 1 0.8 91.2 0.9 85 Example 2 1.0 90.8 1.5 82 Example 3 1.2 89.7 1.9 80 Example 4 1.2 90.2 1.6 83 Comparative Example 1 5.0 81.4 10.6 68 Comparative Example 2 3.0 85.7 7.3 74 As shown in Table 2, the functional coating of the vehicle film in the embodiment has good toughness, high compatibility with TPU base film, can meet the application requirements of most paint surface shapes, and has high light transmittance, high gloss, and low haze, resulting in excellent appearance.

[0049] In the description of this specification, the references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the present invention. In this specification, the illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0050] The above description is merely an example and illustration of the present invention. Those skilled in the art can make various modifications or additions to the specific embodiments described, or use similar methods to replace them, as long as they do not deviate from the invention or exceed the scope defined in the claims, all of which should fall within the protection scope of the present invention.

Claims

1. A scratch-resistant automotive film, comprising a multi-layered composite structure, including, from the paint-coating side outwards: The pressure-sensitive adhesive layer, TPU base film, functional coating, and release film are characterized in that the functional coating is formed by curing a slurry, which, by weight, comprises: 100 parts liquid silicone rubber, 4.8-6.5 parts self-healing anti-scratch agent, 3.5-4.5 parts reactive diluent, 0.15-0.2 parts leveling agent, and 0.3-0.4 parts defoamer; The preparation method of the self-healing anti-scratch agent is as follows: Step A1: Mix hydroxyl-terminated silicone oil and anhydrous tetrahydrofuran, cool in a dry nitrogen atmosphere and ice-water bath, slowly add methylvinyl dichlorosilane while controlling the temperature above 10°C, then add triethylamine and heat to 40-50°C to continue the reaction for 2.5-4 hours to prepare homo-alkenylated silicon intermediate. The hydroxyl content of the hydroxyl-terminated silicone oil and the ratio of methylvinyl dichlorosilane, triethylamine and anhydrous tetrahydrofuran are 0.1 mol: 45-50 mmol: 15-20 mL: 70-100 mL. Step A2: Mix the homo-alkenylated silicon intermediate, mercaptoacetaldehyde, and anhydrous ethanol, purge with nitrogen to remove oxygen, then add benzoin dimethyl ether and mix. Simultaneously, irradiate with an ultraviolet light source and stir for 6-8 hours to prepare the aldehyde-modified matrix. The ratio of homo-alkenylated silicon intermediate, mercaptoacetaldehyde, benzoin dimethyl ether, and anhydrous ethanol is 25g: 50-60mmol: 25-35mg: 120-150mL. Step A3: Premix amine phenyl POSS and dimethylformamide, then add aldehyde-modified matrix and mix well. Under nitrogen protection, heat to 80-100℃, add p-toluenesulfonic acid and stir for 12-16 hours to prepare a self-healing anti-scratch agent. The ratio of aldehyde-modified matrix, amine phenyl POSS, p-toluenesulfonic acid and dimethylformamide is 25g: 10-15mmol: 0.1-0.13g: 270-330mL.

2. The method for preparing a scratch-resistant automotive film according to claim 1, characterized in that, Specifically: Step S1: Premix the self-healing anti-scratch agent, reactive diluent, leveling agent and defoamer, then add them to the liquid silicone rubber and mix well to make a slurry; Step S2: The slurry is evenly coated onto the surface of the TPU base film, and then the film is dried and cured in stages to form a functional coating on the TPU base film. Then, a pressure-sensitive adhesive layer is coated on the bottom layer of the TPU base film, and a release film is attached to the surface of the functional coating to obtain the automotive film.

3. The method for preparing a scratch-resistant automotive film according to claim 2, characterized in that, Both the defoamer and the leveling agent are silicone preparations.

4. The method for preparing a scratch-resistant automotive film according to claim 2, characterized in that, The coating amount of the functional coating slurry is 7.5-9.2 g / m². 2 .

5. The method for preparing a scratch-resistant automotive film according to claim 2, characterized in that, The process parameters for segmented drying and curing are set as follows: the temperature of the first segment is 50-60℃ and the time is 8-10 min; the temperature of the second segment is 82-88℃ and the time is 15-20 min.