A protective film for a vehicle display screen and a method of manufacturing the same

Abstract

This invention relates to the field of protective film technology, and more particularly to a protective film for automotive displays and its preparation method. The protective film for automotive displays of this invention comprises, sequentially, a release layer, an adhesive layer, and a PET substrate layer. The adhesive layer is obtained by curing an adhesive, which, by weight, comprises: 20-50 parts epoxy acrylate, 5-15 parts isooctyl acrylate, 3-8 parts hydroxyethyl acrylate, 3-10 parts lauryl acrylate, 3-6 parts modified silica, 1-2 parts crosslinking agent, 0.5-2 parts photoinitiator, 0.5-1.5 parts antioxidant, and 10-30 parts solvent. The protective film for automotive displays of this invention exhibits excellent peel performance and high-temperature resistance, resisting the effects of the high-temperature environment in automotive environments. Furthermore, the protective film of this invention also possesses excellent anti-yellowing properties, high light transmittance, and excellent antibacterial properties, inhibiting bacterial growth at the edges and seams of the protective film.

Description

Technical Field

[0001] This invention relates to the field of protective film technology, and in particular to a protective film for automotive displays and its preparation method. Background Technology

[0002] With the rapid development of intelligent vehicles, in-vehicle displays have evolved from simple monochrome displays to full-color, large-size, and diversified displays, becoming an important symbol of automotive intelligence, and market demand continues to expand. To prevent scratches or wear on in-vehicle displays, protective films are usually applied to their surfaces. The in-vehicle environment presents more stringent challenges to displays than consumer electronics.

[0003] Currently, most common protective films are made with PVC or PET as the base material, coated with acrylic adhesive, and then laminated with a release film. However, the unique characteristics of the automotive environment place higher demands on the performance of protective films: automotive displays are exposed to complex environmental conditions for extended periods. High temperatures inside cars in summer can easily cause film deformation and delamination due to prolonged exposure to high temperatures; continuous direct sunlight and strong ultraviolet radiation can cause aging, yellowing, and decreased light transmittance; rain, snow, and humid weather can also affect display quality and lifespan. Furthermore, the film requires extremely high optical performance, demanding excellent light transmittance without affecting the screen's color reproduction and contrast. Therefore, it is necessary to develop a high-performance protective film suitable for automotive displays to address these issues. Summary of the Invention

[0004] To overcome the shortcomings of existing technologies, one of the objectives of this invention is to provide a protective film for automotive displays. This protective film for automotive displays possesses a combination of properties including high light transmittance, high temperature resistance, UV resistance, excellent peelability, and a certain degree of antibacterial function.

[0005] The second objective of this invention is to provide a method for preparing a protective film for an automotive display screen.

[0006] One of the objectives of this invention is achieved through the following technical solution:

[0007] A protective film for automotive displays, comprising a release layer, an adhesive layer, and a PET substrate layer, wherein the adhesive layer is cured with an adhesive, and the adhesive comprises, by weight: 20-50 parts epoxy acrylate, 5-15 parts isooctyl acrylate, 3-8 parts hydroxyethyl acrylate, 3-10 parts lauryl acrylate, 3-6 parts modified silica, 1-2 parts crosslinking agent, 0.5-2 parts photoinitiator, 0.5-1.5 parts antioxidant, and 10-30 parts solvent; the chemical structural formula of the crosslinking agent is as follows:

[0008] .

[0009] Furthermore, the preparation process of the crosslinking agent is as follows: under the protection of an inert gas, 4-(heptafluoropropylsulfonyl)chlorobenzene and triallylamine are added to chloroform for reaction. After the reaction is completed, the crosslinking agent is obtained by separation, extraction, purification and drying.

[0010] Further, the ratio of 4-(heptafluoropropylsulfonyl)chlorobenzene, triallylamine, and chloroform is 0.5 mmol: 0.5-0.6 mmol: 8-10 mL; the reaction temperature is 75-80 °C, and the reaction time is 24-28 h.

[0011] Furthermore, the preparation process of the modified silica is as follows:

[0012] (1) Disperse silica in toluene, add silane coupling agent, stir the reaction, filter the reaction solution, wash and dry to obtain epoxidized silica;

[0013] (2) Epoxidized silica was dispersed in N,N-dimethylformamide, compound A was added to react, the reaction solution was filtered, washed and dried to obtain modified silica;

[0014] The preparation process of compound A is as follows:

[0015] 2,3-dimercaptopropionic acid was dissolved in ethanol, and sodium ethoxide ethanol solution and 4,6-divinyl-1,3,5-triazine-2-amine were added. The mixture was reacted overnight at room temperature, concentrated by rotary evaporation, and purified to obtain compound A.

[0016] Further, in step (1), the ratio of silica, silane coupling agent and toluene is 2g:0.8-1.5g:80-100mL, and the silane coupling agent is KH-560; the temperature of the stirring reaction is 80-85℃ and the time is 15-20h.

[0017] Further, in step (2), the ratio of the amount of epoxidized silica, compound A and N,N-dimethylformamide is 1g:0.5-1.0g:50-75mL; the reaction temperature is 60-70℃ and the time is 8-16h.

[0018] Further, the ratio of 2,3-dimercaptopropionic acid, 4,6-divinyl-1,3,5-triazine-2-amine, sodium ethoxide ethanol solution, and ethanol is 10 mmol: 10-12 mmol: 5.2-5.5 mL: 30-50 mL; the concentration of the sodium ethoxide ethanol solution is 20-22 wt%.

[0019] Further, the release layer is a PET release film; the photoinitiator is at least one selected from 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; the antioxidant is at least one selected from antioxidant 168, antioxidant 1010, and antioxidant 1076; and the solvent is at least one selected from ethanol and ethyl acetate.

[0020] The second objective of this invention is achieved by the following technical solution:

[0021] A method for preparing a protective film for an automotive display screen includes the following steps:

[0022] (1) According to the proportion, epoxy acrylate, isooctyl acrylate, hydroxyethyl acrylate, lauryl acrylate, modified silica, crosslinking agent, photoinitiator, antioxidant and solvent are stirred and mixed evenly to obtain adhesive;

[0023] (2) The adhesive is applied to the surface of the PET substrate layer and cured to form an adhesive layer. Then, a release layer is attached to the adhesive layer to obtain the final product.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. The vehicle display screen protective film provided by this invention includes a crosslinking agent introduced into the adhesive, which is prepared by reacting 4-(heptafluoropropylsulfonyl)chlorobenzene with triallylamine. This crosslinking agent molecule contains three allyl active sites, and under ultraviolet light initiation, it can undergo free radical copolymerization with the double bonds of monomers such as epoxy acrylate, isooctyl acrylate, and hydroxyethyl acrylate to form a crosslinking network. This structure not only significantly improves the cohesive force of the adhesive layer, leaving no adhesive residue upon removal, but also endows the protective film with excellent peel performance and improves adhesion stability. Simultaneously, the trifluoromethylsulfonyl group in the molecule can synergistically work with the crosslinking network to enhance the heat resistance of the adhesive layer and resist the effects of the high-temperature environment in the vehicle; furthermore, the quaternary ammonium salt structure can form ionic bonds with the hydroxyl and carboxyl groups in the adhesive layer, further strengthening the adhesion of the adhesive layer.

[0026] 2. This invention also incorporates modified silica as a functional filler. This modified silica is obtained by grafting epoxidized silica with compound A, which is synthesized from 2,3-dimercaptopropionic acid and 4,6-divinyl-1,3,5-triazine-2-amine. The heterocyclic structure of compound A contains sulfur and nitrogen heteroatoms, which can effectively absorb and dissipate ultraviolet energy. Combined with the reflective properties of silica itself, the two work synergistically to reduce ultraviolet light transmittance. This not only inhibits the yellowing and aging of the acrylate adhesive layer due to ultraviolet irradiation but also blocks ultraviolet light from damaging the polarizer of the display screen, preventing the polarizer from aging and yellowing. Simultaneously, the carboxylic acid groups in compound A can form intermolecular hydrogen bonds with components such as epoxy acrylate. Its heterocyclic structure can also entangle with acrylate segments through van der Waals forces and hydrophobic interactions, significantly improving the uniformity of silica dispersion in the adhesive layer, ensuring the high transmittance of the protective film, and meeting the optical requirements of automotive displays.

[0027] 3. The quaternary ammonium salt structure in the crosslinking agent molecule of the present invention works synergistically with the nitrogen heterocyclic groups contained in compound A grafted on the modified silica surface, thus exhibiting excellent antibacterial properties and effectively inhibiting bacterial growth at the edge gaps of the protective film, thereby preventing the erosion of the adhesive layer by bacterial metabolites.

[0028] 4. The preparation method of the protective film for vehicle display screen provided by the present invention is relatively simple and conducive to large-scale industrial production. Attached Figure Description

[0029] Figure 1 The infrared spectrum of the modified silica obtained in Example 1 of this invention is shown. Detailed Implementation

[0030] The present invention will now be further described with reference to the accompanying drawings and specific embodiments. It should be noted that, without conflict, the various embodiments or technical features described below can be arbitrarily combined to form new embodiments. Specific conditions not specified in the embodiments are performed according to conventional conditions or conditions recommended by the manufacturer. Unless otherwise specified, all reagents or instruments used are conventional products obtained through commercial channels.

[0031] Example 1

[0032] A protective film for automotive displays comprises a release layer (PET release film), an adhesive layer, and a PET substrate layer. The adhesive layer is prepared by curing an adhesive, which, by weight, comprises: 40 parts epoxy acrylate, 10 parts isooctyl acrylate, 5 parts hydroxyethyl acrylate, 8 parts lauryl acrylate, 5 parts modified silica, 1.5 parts crosslinking agent, 1 part photoinitiator (1-hydroxycyclohexylphenyl ketone), 1 part antioxidant (antioxidant 168), and 20 parts solvent (ethanol).

[0033] The preparation process of the crosslinking agent is as follows:

[0034]

[0035] Under nitrogen protection, 4-(heptafluoropropylsulfonyl)chlorobenzene (CAS: 65538-06-9) and triallylamine were added to chloroform, with the molar ratio of 4-(heptafluoropropylsulfonyl)chlorobenzene, triallylamine, and chloroform being 0.5 mmol:0.55 mmol:9 mL. After reacting at 75 °C for 26 h, the reaction was quenched with water, the organic phase was separated, the aqueous phase was extracted with chloroform, the organic phase was concentrated by rotary evaporation, and the residue was purified by column chromatography and vacuum dried to obtain the crosslinking agent (yield 90.7%). 1 HNMR: (400MHz, DMSO-d6) δ: 3.89-3.93 (d, 6H), 5.01-5.09 (m, 6H), 5.68-5.72 (m, 3H), 7.33-7.37 (d, 2H), 7.78-7.82 (d, 2H). MS (ESI) m / z=446.10 [M].

[0036] The preparation process of modified silica is as follows:

[0037] (1) Silica was ultrasonically dispersed in toluene, and silane coupling agent KH-560 was added, wherein the ratio of silica, silane coupling agent KH560 and toluene was 2g:1.2g:90mL; after stirring at 80℃ for 18h, the mixture was filtered, washed with ethanol, and dried under vacuum to obtain epoxidized silica.

[0038] (2) The preparation process of compound A is as follows:

[0039]

[0040] 2,3-Dimercaptopropionic acid was dissolved in ethanol, and then 21 wt.% sodium ethoxide ethanol solution and 4,6-divinyl-1,3,5-triazine-2-amine (CAS: 149037-13-8) were added sequentially. The ratio of 2,3-dimercaptopropionic acid, 4,6-divinyl-1,3,5-triazine-2-amine, sodium ethoxide ethanol solution, and ethanol was 10 mmol:11 mmol:5.4 mL:40 mL. After reacting overnight at room temperature, the mixture was concentrated by rotary evaporation, and the residue was purified by column chromatography to give compound A (yield 61.8%). 1 HNMR: (C 10 H 14O2N4S2, 400MHz, DMSO-d6) δ: 2.70-2.84 (m, 4H), 2.88-2.96 (m, 5H), 3.15-3.19 (m, H), 3.66-3.70 (m, H), 7.69 (s, 2H), 12.67 (s, H). MS (ESI) m / z=286.06 [M];

[0041] (3) Epoxy silica was ultrasonically dispersed in N,N-dimethylformamide, and compound A was added, wherein the ratio of epoxy silica, compound A and N,N-dimethylformamide was 1g:0.8g:60mL; after reacting at 65℃ for 12h, the mixture was filtered, washed with ethanol, and dried under vacuum to obtain modified silica.

[0042] A method for preparing a protective film for an automotive display screen includes the following steps:

[0043] (1) According to the proportion, epoxy acrylate, isooctyl acrylate, hydroxyethyl acrylate, lauryl acrylate, modified silica, crosslinking agent, photoinitiator, antioxidant and solvent are stirred and mixed evenly to obtain adhesive;

[0044] (2) The above adhesive is applied to the surface of the PET substrate layer and cured completely by ultraviolet light to form an adhesive layer. Then, the release layer is attached to the adhesive layer to obtain the final product.

[0045] Example 2

[0046] A protective film for automotive displays comprises a release layer (PET release film), an adhesive layer, and a PET substrate layer. The adhesive layer is prepared by curing an adhesive, which, by weight, comprises: 20 parts epoxy acrylate, 5 parts isooctyl acrylate, 3 parts hydroxyethyl acrylate, 3 parts lauryl acrylate, 3 parts modified silica, 1 part crosslinking agent, 0.5 parts photoinitiator (2-hydroxy-2-methyl-1-phenyl-1-propanone), 0.5 parts antioxidant (antioxidant 1010), and 10 parts solvent (ethyl acetate).

[0047] The preparation process of the crosslinking agent is as follows:

[0048] Under nitrogen protection, 4-(heptafluoropropylsulfonyl)chlorobenzene and triallylamine were added to chloroform, with a molar ratio of 0.5 mmol:0.5 mmol:8 mL for 4-(heptafluoropropylsulfonyl)chlorobenzene, triallylamine, and chloroform. After reacting at 75 °C for 28 h, the reaction was quenched with water, the organic phase was separated, the aqueous phase was extracted with chloroform, and the organic phase was concentrated by rotary evaporation. The residue was purified by column chromatography and dried under vacuum to obtain the crosslinking agent (yield 88.6%). 1The HNMR and MS (ESI) m / z results are the same as in Example 1.

[0049] The preparation process of modified silica is as follows:

[0050] (1) Disperse silica in toluene by ultrasonication, add silane coupling agent KH-560, wherein the ratio of silica, silane coupling agent KH560 and toluene is 2g:0.8g:80mL; stir at 80℃ for 20h, filter, wash with ethanol, and vacuum dry to obtain epoxidized silica;

[0051] (2) The preparation process of compound A is as follows:

[0052] 2,3-Dimercaptopropionic acid was dissolved in ethanol, and then 21 wt% sodium ethoxide ethanol solution and 4,6-divinyl-1,3,5-triazine-2-amine were added sequentially. The ratio of 2,3-dimercaptopropionic acid, 4,6-divinyl-1,3,5-triazine-2-amine, sodium ethoxide ethanol solution, and ethanol was 10 mmol:10 mmol:5.2 mL:30 mL. After reacting overnight at room temperature, the mixture was concentrated by rotary evaporation, and the residue was purified by column chromatography to give compound A (yield 60.5%). 1 The HNMR and MS (ESI) m / z results are the same as in Example 1;

[0053] (3) Epoxy silica was ultrasonically dispersed in N,N-dimethylformamide, and compound A was added, wherein the ratio of epoxy silica, compound A and N,N-dimethylformamide was 1g:0.5g:50mL; after reacting at 60℃ for 16h, the mixture was filtered, washed with ethanol, and dried under vacuum to obtain modified silica.

[0054] A method for preparing a protective film for an automotive display screen, the specific preparation steps are the same as in Example 1.

[0055] Example 3

[0056] A protective film for automotive displays comprises a release layer (PET release film), an adhesive layer, and a PET substrate layer. The adhesive layer is prepared by curing an adhesive, which, by weight, comprises: 50 parts epoxy acrylate, 15 parts isooctyl acrylate, 8 parts hydroxyethyl acrylate, 10 parts lauryl acrylate, 6 parts modified silica, 2 parts crosslinking agent, 2 parts photoinitiator (2,4,6-trimethylbenzoyl-diphenylphosphine oxide), 1.5 parts antioxidant (antioxidant 1076), and 30 parts solvent (ethanol).

[0057] The preparation process of the crosslinking agent is as follows:

[0058] Under nitrogen protection, 4-(heptafluoropropylsulfonyl)chlorobenzene and triallylamine were added to chloroform, with a molar ratio of 0.5 mmol:0.6 mmol:10 mL. After reacting at 80 °C for 24 h, the reaction was quenched with water, the organic phase was separated, the aqueous phase was extracted with chloroform, and the organic phase was concentrated by rotary evaporation. The residue was purified by column chromatography and dried under vacuum to obtain the crosslinking agent (yield 89.8%). 1 The HNMR and MS (ESI) m / z results are the same as in Example 1.

[0059] The preparation process of modified silica is as follows:

[0060] (1) Disperse silica in toluene by ultrasonication, add silane coupling agent KH-560, wherein the ratio of silica, silane coupling agent KH560 and toluene is 2g:1.5g:100mL; stir at 85℃ for 15h, filter, wash with ethanol, and vacuum dry to obtain epoxidized silica;

[0061] (2) The preparation process of compound A is as follows:

[0062] 2,3-Dimercaptopropionic acid was dissolved in ethanol, and then 21 wt% sodium ethoxide ethanol solution and 4,6-divinyl-1,3,5-triazine-2-amine were added sequentially, wherein the volume ratio of 2,3-dimercaptopropionic acid, 4,6-divinyl-1,3,5-triazine-2-amine, sodium ethoxide ethanol solution, and ethanol was 10 mmol: 12 mmol: 5.5 mL: 50 mL. After reacting overnight at room temperature, the mixture was concentrated by rotary evaporation, and the residue was purified by column chromatography to give compound A (yield 61.2%). 1 The HNMR and MS (ESI) m / z results are the same as in Example 1;

[0063] (3) Epoxy silica was ultrasonically dispersed in N,N-dimethylformamide, and compound A was added, wherein the ratio of epoxy silica, compound A and N,N-dimethylformamide was 1 g: 1.0 g: 75 mL; after reacting at 70 °C for 8 h, the mixture was filtered, washed with ethanol, and dried under vacuum to obtain modified silica.

[0064] A method for preparing a protective film for an automotive display screen, the specific preparation steps are the same as in Example 1.

[0065] Comparative Example 1

[0066] Comparative Example 1 is basically the same as Example 1, except that the crosslinking agent is omitted; otherwise, it is consistent with Example 1.

[0067] Comparative Example 2

[0068] Comparative Example 2 is basically the same as Example 1, except that silicon dioxide is used instead of modified silicon dioxide; otherwise, it is consistent with Example 1.

[0069] Experimental Example 1

[0070] The modified silica obtained in Example 1 of this invention was subjected to infrared testing, and its infrared spectrum is shown below. Figure 1 As shown.

[0071] Depend on Figure 1 It can be seen that, compared to untreated silica, epoxidized silica has a higher concentration at 2865 cm⁻¹. -1 The presence of a characteristic absorption peak for the methylene group at 3500 cm⁻¹ indicates successful preparation of epoxidized silica; compared to epoxidized silica, modified silica exhibits a higher absorption peak at 3500 cm⁻¹. -1 Characteristic absorption peaks for carboxyl and hydroxyl groups appear on both sides, at 1750 and 1630 cm⁻¹. -1 The presence of characteristic absorption peaks for C=O and -NH- indicates that the modified silica was successfully prepared.

[0072] Experimental Example 2

[0073] 1. The protective films obtained in Examples 1-3 and Comparative Examples 1-2 were peeled off to remove the release layer, and the adhesive layer was then applied to the glass. The peel strength of the adhesive layer was tested according to the standard GB / T 2792-2014. The test results are shown in Table 1.

[0074] 2. The protective films obtained in Examples 1-3 and Comparative Examples 1-2 were peeled off to remove the release layer. The adhesive layer was then placed in an environment of 85°C and 90% relative humidity for 48 hours. The results were observed to determine if the adhesive layer exhibited delamination, cracking, bubbling, or edge lifting. The test results are shown in Table 1.

[0075] 3. Optical performance: The protective films obtained in Examples 1-3 and Comparative Examples 1-2 were peeled off to remove the release layer, and the transmittance and haze were tested according to the test method of GB / T2410-2008. The test results are shown in Table 2.

[0076] 4. Antibacterial rate: Take the protective films obtained in Examples 1-3 and Comparative Examples 1-2, remove the release layer, sterilize under ultraviolet light for 30 minutes, and use them as samples for testing. Then, use Staphylococcus aureus bacterial suspension (1×10⁻⁶) as the test sample. -5 The bacterial culture (CFU / mL) was added dropwise to the surface of the sample and incubated at 37℃ for 8 hours. 20 μL of the incubated bacterial solution was then spread onto a culture medium and incubated at 37℃ for 24 hours. The number of colonies on the culture medium was calculated, and a blank control group was also included. The antibacterial rate was calculated using the following formula: Antibacterial rate (%) = (Number of colonies in the blank control group - Number of colonies in the sample group) / Number of colonies in the blank control group. The experimental results are shown in Table 2.

[0077] 5. Yellowing Index: The protective films obtained in Examples 1-3 and Comparative Examples 1-2 were peeled off to remove the release layer. The adhesive layer was placed in a QUV test chamber with an ultraviolet wavelength of 313 nm, a power of 0.75 W, a test temperature of 60 °C, and a relative humidity of 90%. The ultraviolet irradiation time was 2400 h. The test was then conducted according to the standard GB / T 39822-2021. The test results are shown in Table 2.

[0078] Table 1

[0079]

[0080] Table 2

[0081]

[0082] As shown in Table 1, the adhesive layers obtained in Examples 1-3 of this invention have good peel strength; no adhesive residue remains upon removal; and good resistance to high temperature and humidity, resisting the effects of high-temperature environments in vehicles. Comparative Example 1, which omits the crosslinking agent, shows a significant decrease in peel strength compared to Example 1, with adhesive residue remaining upon removal, and poorer resistance to high temperature and humidity.

[0083] As shown in Table 2, the adhesive layer obtained by this invention exhibits excellent antibacterial properties, with an antibacterial rate exceeding 90%. The antibacterial rates of Comparative Examples 1 and 2 both decreased. This is because the crosslinking agent of this invention contains a quaternary ammonium salt structure, and the nitrogen heterocyclic groups contained in Compound A grafted onto the modified silica surface both possess certain antibacterial properties. Their synergistic effect results in a protective film with excellent antibacterial properties, effectively inhibiting bacterial growth at the edges and crevices of the protective film.

[0084] The yellowing index of the adhesive layer obtained by this invention is lower than that of Comparative Examples 1 and 2, which can inhibit the yellowing of the protective film. The yellowing index of Comparative Example 2 is significantly reduced. This is because the modified silica structure of this application contains sulfur and nitrogen heteroatoms, which can effectively absorb and dissipate ultraviolet energy. Combined with the reflective effect of silica itself on ultraviolet light, the two work together to reduce the ultraviolet light transmittance. This can both inhibit the yellowing and aging of the acrylic adhesive layer due to ultraviolet irradiation and block ultraviolet light from passing through the adhesive layer and damaging the polarizer of the display screen, thus preventing the polarizer from aging and yellowing.

[0085] Furthermore, the protective film of the present invention exhibits excellent transparency, meeting the optical requirements of automotive protective films. In Comparative Example 2, replacing modified silica with silicon dioxide resulted in poorer uniformity of silica dispersion in the adhesive layer, decreased light transmittance, and increased haze.

[0086] The above embodiments are merely preferred embodiments of the present invention and should not be construed as limiting the scope of protection of the present invention. Any non-substantial changes and substitutions made by those skilled in the art based on the present invention shall fall within the scope of protection claimed by the present invention.

Claims

1. A protective film for a vehicle-mounted display screen, characterized in that, The protective film for the vehicle display screen is composed of a release layer, an adhesive layer, and a PET substrate layer. The adhesive layer is obtained by curing an adhesive, which, by weight, comprises: 20-50 parts epoxy acrylate, 5-15 parts isooctyl acrylate, 3-8 parts hydroxyethyl acrylate, 3-10 parts lauryl acrylate, 3-6 parts modified silica, 1-2 parts crosslinking agent, 0.5-2 parts photoinitiator, 0.5-1.5 parts antioxidant, and 10-30 parts solvent; the chemical structural formula of the crosslinking agent is as follows: ； The preparation process of the modified silica is as follows: (1) Disperse silica in toluene, add silane coupling agent, stir the reaction, filter the reaction solution, wash and dry to obtain epoxidized silica; (2) Epoxidized silica was dispersed in N,N-dimethylformamide, compound A was added to react, the reaction solution was filtered, washed and dried to obtain modified silica; The ratio of silica, silane coupling agent, and toluene is 2g:0.8-1.5g:80-100mL, and the silane coupling agent is KH-560; the ratio of epoxidized silica, compound A, and N,N-dimethylformamide is 1g:0.5-1.0g:50-75mL. The preparation process of compound A is as follows: ， 2,3-Dimercaptopropionic acid was dissolved in ethanol, and sodium ethoxide ethanol solution and 4,6-divinyl-1,3,5-triazine-2-amine were added. The mixture was reacted overnight at room temperature, concentrated by rotary evaporation, and purified to obtain compound A. The ratio of 2,3-dimercaptopropionic acid, 4,6-divinyl-1,3,5-triazine-2-amine, sodium ethoxide ethanol solution, and ethanol was 10 mmol: 10-12 mmol: 5.2-5.5 mL: 30-50 mL.

2. The protective film for vehicle-mounted displays according to claim 1, characterized in that, The preparation process of the crosslinking agent is as follows: under the protection of an inert gas, 4-(heptafluoropropylsulfonyl)chlorobenzene and triallylamine are added to chloroform for reaction. After the reaction is completed, the crosslinking agent is obtained by separation, extraction, purification and drying.

3. The protective film for vehicle-mounted displays according to claim 2, characterized in that, The ratio of 4-(heptafluoropropylsulfonyl)chlorobenzene, triallylamine, and chloroform is 0.5 mmol: 0.5-0.6 mmol: 8-10 mL; the reaction temperature is 75-80 °C, and the reaction time is 24-28 h.

4. The protective film for vehicle-mounted displays according to claim 1, characterized in that, In step (1), the temperature of the stirring reaction is 80-85℃ and the time is 15-20h.

5. The protective film for vehicle-mounted displays according to claim 1, characterized in that, In step (2), the reaction temperature is 60-70℃ and the time is 8-16h.

6. The protective film for vehicle-mounted displays according to claim 1, characterized in that, The concentration of the sodium ethoxide ethanol solution is 20-22 wt%.

7. The protective film for vehicle-mounted displays according to claim 1, characterized in that, The release layer is a PET release film; the photoinitiator is at least one of 1-hydroxycyclohexylphenyl ketone, 2-hydroxy-2-methyl-1-phenyl-1-propanone, and 2,4,6-trimethylbenzoyl-diphenylphosphine oxide; the antioxidant is at least one of antioxidant 168, antioxidant 1010, and antioxidant 1076; and the solvent is at least one of ethanol and ethyl acetate.

8. The method for preparing the protective film for an in-vehicle display screen according to any one of claims 1-7, characterized in that, Includes the following steps: (1) According to the proportion, epoxy acrylate, isooctyl acrylate, hydroxyethyl acrylate, lauryl acrylate, modified silica, crosslinking agent, photoinitiator, antioxidant and solvent are stirred and mixed evenly to obtain adhesive; (2) The adhesive is applied to the surface of the PET substrate layer and cured to form an adhesive layer. Then, a release layer is attached to the adhesive layer to obtain the final product.

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