A self-healing optical film and its preparation method

Abstract

This case relates to a self-healing optical film and its preparation method. The optical film is made by adding a nanoparticle suspension to PET masterbatch as the main material during its melt extrusion process, resulting in a cast sheet. After biaxial stretching, a self-healing coating liquid is coated online, followed by shaping and cooling. The nanoparticle suspension includes nano-titanium oxide, MAH-PET polymer, ATO nanoparticles, and titanate coupling agent. The self-healing coating liquid is produced by core-shell emulsion polymerization, forming a nano-silica hard core and an acrylate functional monomer polymer soft shell. This invention adds the nanoparticle suspension by in-situ feeding in the middle of the extruder, reducing steps, improving dispersion uniformity, and making the film surface smoother. Then, the self-healing coating liquid is applied online after longitudinal stretching and before transverse stretching, forming a film on the film surface, improving the hardness and scratch resistance of the film material, enabling rapid self-healing at room temperature, strong stability, and avoiding the occurrence of rainbow patterns.

Description

Technical Field

[0001] This invention relates to the field of optical-grade PET film technology, specifically to an optical film with self-healing function and its preparation method. Background Technology

[0002] Biaxially oriented polyethylene terephthalate (BOPET) film, with its excellent tensile strength, electrical insulation, optical properties, weather resistance, and dimensional stability, has become a core material in packaging, magnetic recording, imaging, and electronic devices. In today's rapidly developing electronic technology landscape, LCD screens, as key components of digital products, face the challenges of being easily scratched and lacking sufficient impact resistance, necessitating high-performance protective films. Although PET material is widely chosen as a substrate for display screen coatings due to its comprehensive properties, traditional BOPET films still suffer from problems such as low hardness, poor heat resistance, and susceptibility to wear. Currently, research on the self-healing properties of optical films based on PET is relatively limited. Optical films also require a certain level of surface smoothness, and friction is inevitable during transportation; scratches can affect product yield and increase costs. Summary of the Invention

[0003] To address the shortcomings of existing technologies, this invention introduces a gradient dispersion molding film formed by in-situ injection of a nanoparticle suspension during the PET melt extrusion process. Subsequently, a self-healing coating liquid is applied to the stretched thin sheet. Through optimization of the internal structure of the film and modification of its surface functions, an optical film with high transmittance and self-healing properties is obtained.

[0004] To achieve the above objectives, the present invention provides the following technical solution:

[0005] A self-healing optical film is produced by adding a nanoparticle suspension to PET masterbatch as the main material during its melt extrusion process, forming a cast sheet, which is then biaxially stretched and coated online with a self-healing coating solution, followed by shaping and cooling.

[0006] The nanoparticle suspension includes nano-titanium oxide, MAH-PET polymer, ATO nanoparticles, and titanate coupling agent;

[0007] The preparation process of the self-healing coating liquid is as follows:

[0008] 1) After the nano-silica is activated, it is dispersed in deionized water and an equal mass of silane coupling agent is added. After the reaction is completed, it is dried to obtain inorganic powder. It is then redispersed in deionized water and initiator ammonium persulfate is added and stirred to make it evenly dispersed for later use.

[0009] 2) Add measured amounts of deionized water and emulsifier to a clean flask and start stirring. Slowly add measured amounts of acrylate hard monomer mixture and stir at high speed to form a stable hard monomer preemulsion.

[0010] 3) In a separate clean flask, add butyl acrylate, hydroxyethyl methacrylate, diacetone acrylamide and the ureidopyrimidinone derivative Upy-C=C, add emulsifier and deionized water and stir until homogeneous. Emulsify rapidly to form a stable functional monomer pre-emulsion.

[0011] 4) Transfer the aqueous dispersion from step 1) to a four-necked flask, introduce nitrogen gas, and heat to 70°C. Slowly add the monomer pre-emulsion from step 2) to the four-necked flask. After the addition is complete, slowly add the functional monomer pre-emulsion from step 3) to the reaction flask, while simultaneously slowly adding ammonium persulfate aqueous solution. After the addition is complete, keep the reaction at the temperature for 2-4 hours.

[0012] 5) Cool to 40~50℃, slowly add the measured amount of adipic acid dihydrazide aqueous solution, adjust the pH to 7.5~8.0 after the addition is complete, cool to room temperature, adjust the solid content to 35~40wt%, and add 1~2wt% of the solid content of the photoinitiator to obtain the product.

[0013] Furthermore, the amount of the nanoparticle suspension added is 10% of the PET masterbatch mass; the coating amount of the coating liquid is 5 g / m³. 2 ~15 g / m 2 .

[0014] Furthermore, the nanoparticle suspension comprises, by weight percentage, 30-40% nano-titanium oxide, 10-20% MAH-PET polymer, 10-15% ATO nanoparticles, 3-5% titanate coupling agent, and the balance being ethylene glycol.

[0015] Further, in step 1), the nano-silica is activated with potassium hydroxide, and the silane coupling agent is γ-aminopropyltriethoxysilane; the mass ratio of nano-silica, silane coupling agent and initiator is 1:1.2~1.5:0.01~0.1.

[0016] Further, in step 2), the acrylate hard monomer mixture is a mixture of methyl methacrylate and styrene in a mass ratio of 3 to 5:1, and the emulsifier is OP-10.

[0017] Furthermore, the structural formula of the ureidopyrimidinone derivative Upy-C=C is as follows: .

[0018] Further, in step 3), the mass ratio of butyl acrylate, hydroxyethyl methacrylate, diacetone acrylamide, and ureidopyrimidinone derivative Upy-C=C is 10:1.5~2.5:2~3:1~1.2; the mass ratio of the hard monomer mixture to the functional monomer mixture is 40~50:60~50.

[0019] Furthermore, the photoinitiator is TPO; the amount of adipic acid dihydrazide is 1 to 1.1 times the molar amount of diacetone acrylamide.

[0020] The present invention further provides a method for preparing the above-mentioned optical film with self-healing function, comprising the following steps:

[0021] S1. After drying the PET masterbatch, it is fed into the extruder. In the middle section of the extruder, a nanoparticle suspension is added through a feeding device. The mixture is then extruded through the die to form a cast sheet.

[0022] S2. The casting sheet is longitudinally stretched into a thin blank, and a self-healing coating liquid is applied to the thin blank using an online coating method.

[0023] S3. The coated sheet is stretched laterally, and then rapidly cured under high temperature heating and ultraviolet light in the shaping section of the laterally stretched area to obtain a PET film with a surface coating.

[0024] S4. After relaxation and cooling, it is wound up under the traction of the traction roller to obtain the final product.

[0025] Furthermore, the longitudinal stretching ratio is 2.8~3.5:1, and the temperature is 90~100℃; the transverse stretching ratio is 3.5~4.5:1, and the temperature is 105~115℃; the ultraviolet irradiation conditions are: wavelength 320-390nm, intensity 400-600mJ / cm², and exposure time 2-5s.

[0026] This invention uses PET masterbatch as the main raw material and chemically modifies it to prepare an optical film with self-healing properties. The nanoparticle suspension contains nano-titanium oxide, maleic anhydride-grafted polyethylene terephthalate (MAH-PET), nano-tin oxide (ATO nanoparticles), and a small amount of titanate coupling agent. Adding it to PET effectively improves the hardness of the film material and imparts antistatic properties. This invention innovatively injects the nanoparticle suspension in situ during the PET extrusion process, eliminating the need for nanoparticle drying and avoiding damage to the nanoparticles caused by high-speed shearing in the initial feeding stage. The in-situ grafting reaction of MAH-PET with PET as a compatibilizer greatly improves the dispersion uniformity of nano-titanium oxide and ATO nanoparticles in PET, resulting in a PET preform with good smoothness and high light transmittance. Furthermore, it enhances adhesion and bonding strength with the coating layer during subsequent coating processes.

[0027] After longitudinal stretching and before transverse stretching, a self-healing coating liquid is applied to the PET film via online coating. The self-healing coating liquid is prepared by core-shell emulsion polymerization, using activated nano-silica as the core. It is first treated with an aminosilane coupling agent, and ammonium persulfate is added to the dispersion to form a cationic dispersion, which can initiate the polymerization of acrylate monomers. Methyl methacrylate and styrene are used as hard monomers to prepolymerize on the surface of nano-silica to form a SiO2 / polymer hard core. Then, a series of functional monomers are added to its surface to form a soft shell. The functional monomers adopt a dual-action crosslinking system, namely the reversible recombination of acylhydrazone bonds of diacetone acrylamide and the breaking and recombination of Upy quadruple hydrogen bonds to achieve the self-healing of the film material. The synergy is enhanced, providing rapid self-healing while providing long-term stability.

[0028] Compared with the prior art, the beneficial effects of the present invention are as follows: The traditional process for preparing PET film is extrusion granulation-biaxial stretching-traction winding. In the present invention, firstly, during the extrusion granulation process, a nanoparticle suspension is added by in-situ feeding in the middle of the extruder, reducing the number of steps, improving the dispersion uniformity, and making the film surface smoother. Then, after longitudinal stretching and before transverse stretching, a self-healing coating liquid is applied online to form a film on the film surface, improving the hardness and scratch resistance of the film material. It can quickly self-heal at room temperature, has strong stability, and avoids the occurrence of rainbow patterns. Detailed Implementation

[0029] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. 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 skilled in the art without creative effort are within the scope of protection of the present invention.

[0030] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0031] Example 1: An optical film with self-healing function

[0032] S1. After drying the PET masterbatch, it is fed into the extruder. In the middle section of the extruder, 10wt% nanoparticle suspension is added through the feeding device. It is mixed with PET and extruded through the die to form a cast sheet.

[0033] S2. The cast sheet is longitudinally stretched into a thin billet, and then coated online at a rate of 5 g / m². 2 Apply a self-healing coating solution;

[0034] S3. The coated sheet is stretched laterally, and then rapidly cured under high temperature heating and ultraviolet light in the shaping section of the laterally stretched area to obtain a PET film with a surface coating.

[0035] S4. After relaxation and cooling, it is wound up under the traction of the traction roller to obtain the final product.

[0036] In the above process, the longitudinal stretching ratio is 2.8~3.5:1, and the temperature is 90~100℃; the transverse stretching ratio is 3.5~4.5:1, and the temperature is 105~115℃; the ultraviolet irradiation conditions are: wavelength 320-390nm, intensity 400-600mJ / cm², and exposure time 2-5s.

[0037] The nanoparticle suspension comprises, by weight percentage, 30% nano-titanium oxide, 15% MAH-PET polymer, 15% ATO nanoparticles, 3% titanate coupling agent, and the balance being ethylene glycol.

[0038] The preparation process of the self-healing coating liquid is as follows:

[0039] 1) 30 g of nano silica was activated in a 5 wt% potassium hydroxide solution, then redispersed in deionized water and 1.5 times the amount of γ-aminopropyltriethoxysilane (KH550) was added. The mixture was stirred at 50 °C for 24 h, filtered, washed, dried and ground to obtain inorganic powder. The powder was redispersed in deionized water and 1 g of ammonium persulfate was added and stirred to make it evenly dispersed.

[0040] 2) Add 220g of deionized water and 10g of emulsifier OP-10 to a clean flask and start stirring. Slowly add 200g of a mixture of methyl methacrylate and styrene (mass ratio 5 / 1) and stir at high speed to form a stable hard monomer preemulsion.

[0041] 3) In another clean flask, add 150g butyl acrylate, 35g hydroxyethyl methacrylate, 45g diacetone acrylamide and 15g ureidopyrimidinone derivative Upy-C=C, add 10g emulsifier and 265g deionized water and stir until homogeneous. Emulsify quickly to form a stable functional monomer pre-emulsion.

[0042] 4) Transfer the aqueous dispersion from step 1) to a four-necked flask, introduce nitrogen gas, and heat to 70°C. Slowly add the monomer pre-emulsion from step 2) to the four-necked flask. After the addition is complete, slowly add the functional monomer pre-emulsion from step 3) to the reaction flask, while simultaneously slowly adding ammonium persulfate aqueous solution. After the addition is complete, keep the reaction at the temperature for 2-4 hours.

[0043] 5) Cool to 45℃, slowly add an aqueous solution containing 19.5g of adipic acid dihydrazide, adjust the pH to 7.5~8.0 after the addition is complete, cool to room temperature, adjust the solid content to 40wt%, and add 2wt% of the solid content of photoinitiator TPO to obtain the final product.

[0044] Example 2:

[0045] S1. After drying the PET masterbatch, it is fed into the extruder. In the middle section of the extruder, 10wt% nanoparticle suspension is added through the feeding device. It is mixed with PET and extruded through the die to form a cast sheet.

[0046] S2. The cast sheet is longitudinally stretched into a thin billet, and an online coating process is used to coat the thin billet at a rate of 10 g / m². 2 Apply a self-healing coating solution;

[0047] S3. The coated sheet is stretched laterally, and then rapidly cured under high temperature heating and ultraviolet light in the shaping section of the laterally stretched area to obtain a PET film with a surface coating.

[0048] S4. After relaxation and cooling, it is wound up under the traction of the traction roller to obtain the final product.

[0049] In the above process, the longitudinal stretching ratio is 3:1, and the temperature is 90~100℃; the transverse stretching ratio is 3.5:1, and the temperature is 105~115℃; the ultraviolet irradiation conditions are: wavelength 320-390nm, intensity 400-600mJ / cm², and exposure time 2-5s.

[0050] The nanoparticle suspension comprises, by weight percentage, 35% nano-titanium oxide, 15% MAH-PET polymer, 10% ATO nanoparticles, 3% titanate coupling agent, and the balance being ethylene glycol.

[0051] The preparation process of the self-healing coating liquid is as follows:

[0052] 1) 30 g of nano silica was activated in a 5 wt% potassium hydroxide solution, then redispersed in deionized water and 1.5 times the amount of γ-aminopropyltriethoxysilane (KH550) was added. The mixture was stirred at 50 °C for 24 h, filtered, washed, dried and ground to obtain inorganic powder. The powder was redispersed in deionized water and 1 g of ammonium persulfate was added and stirred to make it evenly dispersed.

[0053] 2) Add 220g of deionized water and 10g of emulsifier OP-10 to a clean flask and start stirring. Slowly add 200g of a mixture of methyl methacrylate and styrene (mass ratio 5 / 1) and stir at high speed to form a stable hard monomer preemulsion.

[0054] 3) In another clean flask, add 150g butyl acrylate, 35g hydroxyethyl methacrylate, 45g diacetone acrylamide and 15g ureidopyrimidinone derivative Upy-C=C, add 10g emulsifier and 265g deionized water and stir until homogeneous. Emulsify quickly to form a stable functional monomer pre-emulsion.

[0055] 4) Transfer the aqueous dispersion from step 1) to a four-necked flask, introduce nitrogen gas, and heat to 70°C. Slowly add the monomer pre-emulsion from step 2) to the four-necked flask. After the addition is complete, slowly add the functional monomer pre-emulsion from step 3) to the reaction flask, while simultaneously slowly adding ammonium persulfate aqueous solution. After the addition is complete, keep the reaction at the temperature for 2-4 hours.

[0056] 5) Cool to 45℃, slowly add an aqueous solution containing 19.5g of adipic acid dihydrazide, adjust the pH to 7.5~8.0 after the addition is complete, cool to room temperature, adjust the solid content to 40wt%, and add 2wt% of the solid content of photoinitiator TPO to obtain the final product.

[0057] Example 3:

[0058] S1. After drying the PET masterbatch, it is fed into the extruder. In the middle section of the extruder, 10wt% nanoparticle suspension is added through the feeding device. It is mixed with PET and extruded through the die to form a cast sheet.

[0059] S2. The cast sheet is longitudinally stretched into a thin billet, and an online coating process is used to coat the thin billet at a rate of 10 g / m². 2 Apply a self-healing coating solution;

[0060] S3. The coated sheet is stretched laterally, and then rapidly cured under high temperature heating and ultraviolet light in the shaping section of the laterally stretched area to obtain a PET film with a surface coating.

[0061] S4. After relaxation and cooling, it is wound up under the traction of the traction roller to obtain the final product.

[0062] In the above process, the longitudinal stretching ratio is 3:1, and the temperature is 90~100℃; the transverse stretching ratio is 3.5:1, and the temperature is 105~115℃; the ultraviolet irradiation conditions are: wavelength 320-390nm, intensity 400-600mJ / cm², and exposure time 2-5s.

[0063] The nanoparticle suspension comprises, by weight percentage, 35% nano-titanium oxide, 15% MAH-PET polymer, 10% ATO nanoparticles, 3% titanate coupling agent, and the balance being ethylene glycol.

[0064] The preparation process of the self-healing coating liquid is as follows:

[0065] 1) 30 g of nano silica was activated in a 5 wt% potassium hydroxide solution, then redispersed in deionized water and 1.5 times the amount of γ-aminopropyltriethoxysilane (KH550) was added. The mixture was stirred at 50 °C for 24 h, filtered, washed, dried and ground to obtain inorganic powder. The powder was redispersed in deionized water and 1 g of ammonium persulfate was added and stirred to make it evenly dispersed.

[0066] 2) Add 220g of deionized water and 10g of emulsifier OP-10 to a clean flask and start stirring. Slowly add 200g of a mixture of methyl methacrylate and styrene (mass ratio 5 / 1) and stir at high speed to form a stable hard monomer preemulsion.

[0067] 3) In another clean flask, add 130g butyl acrylate, 26g hydroxyethyl methacrylate, 31g diacetone acrylamide and 13g ureidopyrimidinone derivative Upy-C=C, add 10g emulsifier and 265g deionized water and stir until homogeneous. Emulsify quickly to form a stable functional monomer pre-emulsion.

[0068] 4) Transfer the aqueous dispersion from step 1) to a four-necked flask, introduce nitrogen gas, and heat to 70°C. Slowly add the monomer pre-emulsion from step 2) to the four-necked flask. After the addition is complete, slowly add the functional monomer pre-emulsion from step 3) to the reaction flask, while simultaneously slowly adding an ammonium persulfate aqueous solution. After the addition is complete, keep the reaction at the temperature for 2-4 hours.

[0069] 5) Cool to 45℃, slowly add an aqueous solution containing 13.5g of adipic acid dihydrazide, adjust the pH to 7.5~8.0 after the addition is complete, cool to room temperature, adjust the solid content to 40wt%, and add 2wt% of the solid content of photoinitiator TPO to obtain the final product.

[0070] Example 4:

[0071] S1. After drying the PET masterbatch, it is fed into the extruder. In the middle section of the extruder, 10wt% nanoparticle suspension is added through the feeding device. It is mixed with PET and extruded through the die to form a cast sheet.

[0072] S2. The cast sheet is longitudinally stretched into a thin billet, and an online coating process is used to coat the thin billet at a rate of 10 g / m². 2 Apply a self-healing coating solution;

[0073] S3. The coated sheet is stretched laterally, and then rapidly cured under high temperature heating and ultraviolet light in the shaping section of the laterally stretched area to obtain a PET film with a surface coating.

[0074] S4. After relaxation and cooling, it is wound up under the traction of the traction roller to obtain the final product.

[0075] In the above process, the longitudinal stretching ratio is 3:1, and the temperature is 90~100℃; the transverse stretching ratio is 3.5:1, and the temperature is 105~115℃; the ultraviolet irradiation conditions are: wavelength 320-390nm, intensity 400-600mJ / cm², and exposure time 2-5s.

[0076] The nanoparticle suspension comprises, by weight percentage, 35% nano-titanium oxide, 15% MAH-PET polymer, 10% ATO nanoparticles, 3% titanate coupling agent, and the balance being ethylene glycol.

[0077] The preparation process of the self-healing coating liquid is as follows:

[0078] 1) 30 g of nano silica was activated in a 5 wt% potassium hydroxide solution, then redispersed in deionized water and 1.5 times the amount of γ-aminopropyltriethoxysilane (KH550) was added. The mixture was stirred at 50 °C for 24 h, filtered, washed, dried and ground to obtain inorganic powder. The powder was redispersed in deionized water and 1 g of ammonium persulfate was added and stirred to make it evenly dispersed.

[0079] 2) Add 220g of deionized water and 10g of emulsifier OP-10 to a clean flask and start stirring. Slowly add 200g of a mixture of methyl methacrylate and styrene (mass ratio 5 / 1) and stir at high speed to form a stable hard monomer preemulsion.

[0080] 3) In another clean flask, add 200g butyl acrylate, 35g hydroxyethyl methacrylate, 45g diacetone acrylamide and 20g ureidopyrimidinone derivative Upy-C=C, add 10g emulsifier and 265g deionized water and stir until homogeneous. Emulsify quickly to form a stable functional monomer pre-emulsion.

[0081] 4) Transfer the aqueous dispersion from step 1) to a four-necked flask, introduce nitrogen gas, and heat to 70°C. Slowly add the monomer pre-emulsion from step 2) to the four-necked flask. After the addition is complete, slowly add the functional monomer pre-emulsion from step 3) to the reaction flask, while simultaneously slowly adding an ammonium persulfate aqueous solution. After the addition is complete, keep the reaction at the temperature for 2-4 hours.

[0082] 5) Cool to 45℃, slowly add an aqueous solution containing 13.5g of adipic acid dihydrazide, adjust the pH to 7.5~8.0 after the addition is complete, cool to room temperature, adjust the solid content to 40wt%, and add 2wt% of the solid content of photoinitiator TPO to obtain the final product.

[0083] Comparative Example 1:

[0084] Same as Example 1, except that no nanoparticle suspension was added.

[0085] Comparative Example 2:

[0086] Same as Example 1, except that the coating liquid was not applied online.

[0087] Comparative Example 3:

[0088] Same as Example 1, except that the Upy-C=C monomer is removed.

[0089] In Examples 1-4 and Comparative Examples 1-3, unless otherwise specified, all raw materials used were commercially available. The structural formula of the ureidopyrimidinone derivative Upy-C=C is [insert structural formula here]. ;

[0090] The preparation method is based on the patent, and the synthesis equation is as follows:

[0091] Transmittance and haze were measured using a transmittance and haze meter.

[0092] Surface hardness was tested using the pencil hardness test.

[0093] The self-healing performance test method refers to the test method in "HG / T 5675-2020 Optical Functional Thin Film Self-Healing Hardening Film".

[0094] Stain resistance: Draw a horizontal line on the coating with a marker, leave the note for 1 minute, then wipe it with methyl ethyl ketone (MEK) and observe whether there is any note residue on the film surface.

[0095] The data is recorded in Table 1.

[0096] Table 1

[0097]

[0098] Except for the rainbow effect observed in Comparative Example 1, the optical films prepared in the above embodiments and comparative examples have intact surfaces without any abnormalities. Comparative Example 1 did not contain any nanoparticles, theoretically resulting in high light transmittance, but also low adhesion, which is detrimental to subsequent coating processes and leads to a slight rainbow effect. The optical films of Examples 1-3, in addition to high hardness and light transmittance, also exhibit very good self-healing properties. Example 4, with its increased functional monomers, demonstrates high self-healing properties, but its hardness is correspondingly lower. Comparative Example 2, coated with a common coating solution, has no self-healing properties; Comparative Example 3, lacking Upy-C=C monomers, has relatively weaker self-healing properties compared to Examples 1-4.

[0099] Although the embodiments of the present invention have been disclosed above, they are not limited to the applications listed in the specification and embodiments. They can be applied to various fields suitable for the present invention. For those skilled in the art, other modifications can be easily made. Therefore, without departing from the general concept defined by the claims and their equivalents, the present invention is not limited to the specific details.

Claims

1. An optical film with self-healing function, characterized in that, It is produced by adding a nanoparticle suspension to PET masterbatch as the main material in the middle section of an extruder via a feeding device, resulting in a cast sheet that is biaxially stretched and then coated online with a self-healing coating liquid, followed by shaping and cooling. The nanoparticle suspension includes nano-titanium oxide, MAH-PET polymer, ATO nanoparticles, and titanate coupling agent; The preparation process of the self-healing coating liquid is as follows: 1) After the nano-silica is activated, it is dispersed in deionized water and an equal mass of silane coupling agent is added. After the reaction is completed, it is dried to obtain inorganic powder. It is then redispersed in deionized water and initiator ammonium persulfate is added and stirred to make it evenly dispersed for later use. 2) Add measured amounts of deionized water and emulsifier to a clean flask and start stirring. Slowly add measured amounts of acrylate hard monomer mixture and stir at high speed to form a stable hard monomer preemulsion. 3) In a separate clean flask, add butyl acrylate, hydroxyethyl methacrylate, diacetone acrylamide and the ureidopyrimidinone derivative Upy-C=C, add emulsifier and deionized water and stir until homogeneous. Emulsify rapidly to form a stable functional monomer pre-emulsion. 4) Transfer the aqueous dispersion from step 1) to a four-necked flask, introduce nitrogen gas, and heat to 70°C. Slowly add the monomer pre-emulsion from step 2) to the four-necked flask. After the addition is complete, slowly add the functional monomer pre-emulsion from step 3) to the reaction flask, while simultaneously slowly adding ammonium persulfate aqueous solution. After the addition is complete, keep the reaction at the temperature for 2-4 hours. 5) Cool to 40~50℃, slowly add the measured amount of adipic acid dihydrazide aqueous solution, adjust the pH to 7.5~8.0 after the addition is complete, cool to room temperature, adjust the solid content to 35~40wt%, and add 1~2wt% of photoinitiator by weight of solids to obtain the product; The amount of nanoparticle suspension added is 10% of the mass of PET masterbatch, and the coating amount of coating liquid is 5 g / m³. 2 ~15 g / m 2 ; The structural formula of the ureidopyrimidinone derivative Upy-C=C is: .

2. The optical film with self-healing function as described in claim 1, characterized in that, The nanoparticle suspension comprises, by weight percentage, 30-40% nano-titanium oxide, 10-20% MAH-PET polymer, 10-15% ATO nanoparticles, 3-5% titanate coupling agent, and the balance being ethylene glycol.

3. The optical film with self-healing function as described in claim 1, characterized in that, In step 1), the nano-silica is activated with potassium hydroxide, and the silane coupling agent is γ-aminopropyltriethoxysilane; the mass ratio of nano-silica, silane coupling agent and initiator is 1:1.2~1.5:0.01~0.

1.

4. The optical film with self-healing function as described in claim 1, characterized in that, In step 2), the acrylate hard monomer mixture is a mixture of methyl methacrylate and styrene in a mass ratio of 3 to 5:1, and the emulsifier is OP-10.

5. The optical film with self-healing function as described in claim 1, characterized in that, In step 3), the mass ratio of butyl acrylate, hydroxyethyl methacrylate, diacetone acrylamide, and ureidopyrimidinone derivative Upy-C=C is 10:1.5~2.5:2~3:1~1.2; the mass ratio of the hard monomer mixture to the functional monomer mixture is 40~50:60~50.

6. The optical film with self-healing function as described in claim 1, characterized in that, The photoinitiator is TPO; the amount of adipic acid dihydrazide is 1 to 1.1 times the molar amount of diacetone acrylamide.

7. A method for preparing an optical film with self-healing function as described in any one of claims 1 to 6, characterized in that, Includes the following steps: S1. After drying the PET masterbatch, it is fed into the extruder. In the middle section of the extruder, a nanoparticle suspension is added through a feeding device. The mixture is then extruded through the die to form a cast sheet. S2. The casting sheet is longitudinally stretched into a thin blank, and a self-healing coating liquid is applied to the thin blank using an online coating method. S3. The coated sheet is stretched laterally, and then rapidly cured under high temperature heating and ultraviolet light in the shaping section of the laterally stretched area to obtain a PET film with a surface coating. S4. After relaxation and cooling, it is wound up under the traction of the traction roller to obtain the final product.

8. The method for preparing an optical film with self-healing function as described in claim 7, characterized in that, The longitudinal stretching ratio is 2.8~3.5:1, and the temperature is 90~100℃; the transverse stretching ratio is 3.5~4.5:1, and the temperature is 105~115℃; the ultraviolet irradiation conditions are: wavelength 320-390nm, intensity 400-600mJ / cm², and exposure time 2-5s.

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