High-temperature-resistant acrylic optical cement with high light transmittance and preparation method of high-temperature-resistant acrylic optical cement

Abstract

The invention relates to the technical field of optical cement, in particular to high-temperature-resistant acrylic optical cement with high light transmittance and a preparation method of the high-temperature-resistant acrylic optical cement. The preparation method of the high-light-transmittance high-temperature-resistant acrylic optical adhesive comprises the following steps: (1) under the protection of inert gas, mixing an acrylate monomer, a carboxyl-containing monomer, an epoxy-containing monomer, a hydroxyl-containing monomer, a photoinitiator and modified inorganic nanoparticles, and stirring at 60-90 DEG C and 200-600rpm for 3-8 hours to obtain an adhesive solution; and (2) carrying out vacuum curing on the glue solution at 50-80 DEG C for 5-15 minutes to form a glue material, pressing the glue material into a film, and cooling to obtain the optical cement. The prepared high-temperature-resistant acrylic optical adhesive with high light transmittance has good light transmittance, high-temperature resistance and good peel strength, the light transmittance of the optical adhesive is larger than 90%, the heat-resistant temperature is larger than 150 DEG C, the peel strength is larger than 14 N / 25 mm, and the peel strength after high-temperature treatment is larger than 11.8 N / 25 mm.

Description

Technical Field

[0001] This invention relates to the field of optical adhesive technology, specifically to a high-transmittance, high-temperature resistant acrylic optical adhesive and its preparation method. Background Technology

[0002] With the rapid development of electronic display technology, optical adhesives are increasingly widely used in touchscreens, flexible display devices, and optical lenses. Traditional optical adhesives mostly use acrylate polymers as the matrix material. While these offer high light transmittance and adhesion, they are prone to yellowing, aging, or deterioration of mechanical properties at high temperatures, making it difficult to meet the high-temperature resistance and long-term stability requirements of high-end electronic devices. Furthermore, the inorganic fillers in conventional optical adhesives often have poor dispersibility, easily leading to reduced light transmittance or interface defects, affecting the performance and reliability of optical devices.

[0003] Currently, existing technologies typically introduce nanoparticles such as zirconium oxide and silica to modify acrylate resins to improve heat resistance. However, the compatibility between nanoparticles and the organic matrix is ​​insufficient, leading to agglomeration and a decrease in optical uniformity. Existing technologies use silane coupling agents to modify the surface of nanoparticles, which can improve dispersibility; however, the modified nanoparticles still struggle to fully react with the acrylate monomers, affecting the mechanical strength and thermal stability of the final cured product. Therefore, developing an optical adhesive that combines high light transmittance, excellent high-temperature resistance, and good processability remains a challenge.

[0004] To address the aforementioned issues, there is an urgent need to propose a novel method for preparing acrylic optical adhesives. By optimizing monomer combinations, introducing specifically modified inorganic nanoparticles, and controlling the curing process, the optical adhesive can significantly improve its high-temperature resistance and interfacial bonding strength while maintaining high light transmittance, thereby meeting the application requirements of high-end optical devices. Summary of the Invention

[0005] To address the shortcomings of the existing technology, this invention provides a high-transmittance, high-temperature resistant acrylic optical adhesive and its preparation method.

[0006] To solve the above-mentioned technical problems, the technical solution adopted by the present invention is as follows: A method for preparing a high-transmittance, high-temperature resistant acrylic optical adhesive includes the following steps: (1) Under inert gas protection, acrylate monomers, carboxyl-containing monomers, epoxy-containing monomers, hydroxyl-containing monomers, photoinitiators and modified inorganic nanoparticles are mixed and stirred at 60-90℃ and 200-600rpm for 3-8h to obtain a glue solution. (2) The adhesive liquid is vacuum cured at 50-80℃ for 5-15 minutes to form an adhesive material, and then the adhesive material is pressed into a film and cooled to obtain the optical adhesive.

[0007] Preferably, the weight parts of each component in step (1) are: 60-80 parts of acrylate monomer, 5-10 parts of carboxyl-containing monomer, 40-50 parts of epoxy-containing monomer, 5-10 parts of hydroxyl-containing monomer, 1-5 parts of photoinitiator, and 3-8 parts of modified inorganic nanoparticles.

[0008] Preferably, the acrylate monomer is selected from at least one of borneol methacrylate, methyl methacrylate, and butyl acrylate; the carboxyl-containing monomer is acrylic acid or methacrylic acid; the epoxy-containing monomer is glycidyl methacrylate; and the hydroxyl-containing monomer is at least one of hydroxyethyl methacrylate and 3-hydroxypropyl methacrylate.

[0009] Preferably, the photoinitiator is any one of azobisisobutyronitrile, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexylphenyl ketone, benzoyl tert-butyl peroxide, and 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone.

[0010] Adding inorganic nanomaterials such as zirconium oxide and silica to optical adhesives can improve high-temperature resistance and mechanical strength, while maintaining high light transmittance through optimized dispersibility. Nanoparticles tend to have poor dispersibility in organic matrices and are prone to aggregation due to excessively high surface energy. This aggregation not only reduces the light transmittance of the optical adhesive due to increased light scattering but also creates stress concentration points within the material, weakening its mechanical properties. Furthermore, the bonding between nanoparticles and the organic matrix relies solely on physical adsorption, resulting in weak interfacial adhesion. This makes them susceptible to phase separation at high temperatures or during long-term use, leading to a decrease in the heat resistance and stability of the optical adhesive. Unmodified nanoparticles cannot fully exert their reinforcing effect and may even become a cause of material failure. Therefore, surface modification with double-bonded silanes is necessary to enable them to participate in polymerization reactions, thereby enhancing interfacial adhesion and performance stability.

[0011] Preferably, the modified inorganic nanoparticles are inorganic nanoparticles with polymerizable double bonds on their surface, and their preparation method includes: Inorganic nanoparticles were dispersed in an organic solvent containing carboxyl groups and subjected to ultrasonic treatment to obtain a carboxylated nanoparticle suspension. A silane coupling agent containing amino and / or alkoxy groups is mixed with a silane coupling agent containing double bonds, and then hydrolyzed and condensed under acidic conditions to obtain an organosilane containing double bonds. The carboxylated nanoparticle suspension was reacted with the organosilane containing double bonds to obtain the modified inorganic nanoparticles.

[0012] Surface modification of nanoparticles with double-bonded silanes significantly enhances their compatibility and reactivity with organic matrices. The modified nanoparticles are grafted with polymerizable double bonds, enabling them to copolymerize with acrylate monomers during curing and become part of a cross-linked network. This chemical bonding not only strengthens the interfacial bond between the nanoparticles and the matrix, improving peel strength, but also increases the cross-linking density, resulting in better mechanical properties and thermal stability of the optical adhesive. Furthermore, the modified nanoparticles disperse more uniformly in the adhesive solution, reducing light scattering and maintaining high transmittance (greater than 90%), while also imparting excellent high-temperature resistance (greater than 150°C).

[0013] Specifically, the reaction mechanism of this invention is as follows: S1, using nanoparticles (in some embodiments, zirconium oxide and silicon dioxide) and a carboxyl-containing organic solvent (in some embodiments, adipic acid ethanol solution) as reactants, the nanoparticles are ultrasonically dispersed, and the carboxyl groups are anchored on the particle surface through physical adsorption or weak chemical action to form carboxylated nanoparticles. The purpose of this step is to provide highly reactive carboxyl functional groups on the surface of the nanoparticles, providing reaction sites for subsequent grafting of silane coupling agents. S2, using amino / hydroxyl-containing silanes and double-bonded silanes as reactants, the nanoparticles are hydrolyzed under acidic conditions to generate silanols, which are then condensed to form organosiloxane oligomers containing double bonds. The -NH2 or -OH groups of amino / hydroxysilanes covalently bond with the -COOH groups on the surface of carboxylated nanoparticles through amidation or esterification reactions, while silanes containing double bonds introduce polymerizable C=C bonds. The modified nanoparticles possess a double-bond structure on their surface. During the optical adhesive curing stage, these double bonds undergo free radical copolymerization with acrylate monomers (such as methyl methacrylate) under the action of a photoinitiator, making the nanoparticles nodes in a cross-linked network. This chemical bonding not only inhibits nanoparticle aggregation but also enhances interfacial stress transfer, thereby simultaneously improving light transmittance and heat resistance.

[0014] Furthermore, the preparation method of the modified inorganic nanoparticles is as follows: S1. Add 2-6 parts by weight of inorganic nanoparticles to 100-200 parts by weight of 1-3 g / mL dicarboxylic acid ethanol solution, stir at 55-75℃ and 300-600 rpm for 1-3 h, then place in an ice bath and ultrasonically disperse at an ultrasonic power of 150-260 W and an ultrasonic frequency of 40-70 kHz for 1-4 h to obtain a carboxylated zirconium oxide suspension. S2. Mix 2-5 parts by weight of amino-containing silane coupling agent, 2-5 parts by weight of hydroxyl-containing silane coupling agent, and 3-6 parts by weight of silane coupling agent containing double bonds. Add 5-12 parts by weight of water and 40-80 parts by weight of anhydrous ethanol, and stir until homogeneous to form a mixed solution. Adjust the pH of the solution to 1.5-2.8 with 1-3 mol / mL hydrochloric acid to form a reaction solution. Place the solution under nitrogen protection and react at 50-70℃ for 2-6 hours. Distill under reduced pressure to obtain an organosilane containing double bonds. S3. Take all of the above carboxylated zirconium oxide suspension and 1-3 parts by weight of the above organosilanes containing double bonds, mix them evenly, stir at 55-70℃ and 300-500rpm for 1-4h, centrifuge, wash, and dry to obtain modified inorganic nanoparticles.

[0015] The modified inorganic nanoparticles prepared in this invention are carboxylated to obtain carboxylated nanoparticles, which are then grafted with abundant highly active functional groups. During the composite process with polymers, these nanoparticles provide a large specific surface area, thus preventing the aggregation of nano-ions within the polymer. Their uniform dispersion reduces haze and color difference in optical adhesives, ensuring high light transmittance. Secondly, as crosslinking points participating in the polymerization reaction, they enhance the tensile strength, toughness, and anti-aging properties of the material. Finally, strong interfacial bonding ensures the stability of the optical adhesive at high temperatures, preventing yellowing or degradation of mechanical properties. Furthermore, the modified nanoparticles optimize the curing process, shorten curing time, and improve the waterproof and sealing properties of the product. These characteristics make this optical adhesive more competitive in applications such as high-end display devices and flexible screens.

[0016] Preferably, the inorganic nanoparticles are oxide nanoparticles, including at least one of zirconium oxide, titanium dioxide, and silicon dioxide.

[0017] Preferably, the carboxyl-containing organic solvent is an ethanol solution of a C6-C14 dicarboxylic acid with a concentration of 1-3 g / mL.

[0018] Preferably, the amino-containing silane coupling agent is selected from at least one of aminoethylaminoisobutylmethyldimethoxysilane and γ-aminopropyltriethoxysilane; the hydroxyl-containing silane coupling agent is selected from at least one of N-(3-acryloyloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane; and the double-bonded silane coupling agent is selected from at least one of 3-(methacryloyloxy)propyltrimethoxysilane and vinyltrimethoxysilane.

[0019] Furthermore, the vacuum curing temperature in step (2) is 55-70℃ and the time is 6-10 min.

[0020] A high-transmittance, high-temperature resistant acrylic optical adhesive, prepared by the method described above, has a transmittance greater than 90% and a heat resistance temperature greater than 150℃.

[0021] The beneficial effects of this invention are as follows: 1. This invention provides a high-transmittance, high-temperature resistant acrylic optical adhesive and its preparation method. By optimizing the monomer combination and introducing modified inorganic nanoparticles, the optical properties and high-temperature resistance of the material are significantly improved. Through the synergistic effect of a specific ratio of acrylate monomers and carboxyl / epoxy / hydroxyl monomers, combined with a photoinitiator and modified nanoparticles, a highly uniform adhesive system is formed. The polymerizable double bonds on the surface of the modified nanoparticles undergo a copolymerization reaction with the acrylate matrix during curing, constructing a stable three-dimensional cross-linked network. This results in an optical adhesive with a transmittance greater than 90%, while also possessing excellent interfacial bonding strength and optical uniformity.

[0022] 2. This invention employs a silane coupling agent containing double bonds to modify the surface of inorganic nanoparticles, enabling them to achieve molecular-level dispersion within an organic matrix and avoiding light scattering problems caused by agglomeration. The modified nanoparticles act as active crosslinking points in the polymerization reaction, not only improving peel strength but also significantly enhancing the material's mechanical strength and thermal stability. This results in an optical adhesive with a heat resistance temperature exceeding 150℃ and resistance to yellowing or aging over long-term use, meeting the stringent requirements of high-end electronic devices. The surface modification process of the nanoparticles effectively solves the technical challenge of poor dispersibility of nanofillers in traditional optical adhesives.

[0023] 3. The introduction of silane-modified nanoparticles containing double bonds not only shortens the curing time and improves production efficiency, but also gives the optical adhesive excellent high-temperature resistance, anti-aging properties and sealing performance. These comprehensive performance improvements make the optical adhesive of this invention have broad application prospects in the field of high-end optical devices such as flexible displays and touch screens. Detailed Implementation

[0024] The invention will now be described in further detail with reference to specific embodiments, but it should not be construed as limiting the scope of the invention to the following embodiments.

[0025] The raw materials described in this application are partially described; all other raw materials not described are commercially available. The nano-zirconia was purchased from Beijing Deco Island Gold Technology Co., Ltd., with a particle size of 50nm and model number DK-ZrO2-005-2.

[0026] The nano-silica was purchased from Beijing Deco Island Gold Technology Co., Ltd., with a particle size of 15nm and model number DK-SiO2-15.

[0027] The nano-titanium dioxide was purchased from Ningbo Luofei Nanotechnology Co., Ltd., with a particle size of 20nm and product number LF-TiO2-N20.

[0028] Example 1 A method for preparing a high-transmittance, high-temperature resistant acrylic optical adhesive includes the following steps: (1) Under nitrogen protection, 70 parts by weight of borneol methacrylate, 6 parts by weight of acrylic acid, 45 parts by weight of glycidyl methacrylate, 8 parts by weight of 3-hydroxypropyl methacrylate, 3 parts by weight of azobisisobutyronitrile and 5 parts by weight of modified zirconium oxide were stirred at 78°C and 400 rpm for 6 h to obtain a glue solution. (2) Place the above adhesive liquid in a vacuum drying oven at 65°C for 8 minutes to cure it into an adhesive material. Then press the adhesive material into a sheet film and cool it to obtain a high-transmittance high-temperature resistant acrylic optical adhesive.

[0029] The method for preparing the modified zirconium oxide is as follows: S1. Add 4 parts by weight of nano-zirconia to 150 parts by weight of 2 g / mL adipic acid ethanol solution, stir at 65℃ and 400 rpm for 1.5 h, place in an ice bath, and ultrasonically disperse at ultrasonic power of 200 W and ultrasonic frequency of 60 kHz for 2 h to obtain carboxylated zirconia suspension. S2. Mix 4 parts by weight of aminoethylaminoisobutylmethyldimethoxysilane, 4 parts by weight of N-(3-acryloyloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane, and 5 parts by weight of 3-(methacryloyloxy)propyltrimethoxysilane. Add 8 parts by weight of water and 50 parts by weight of anhydrous ethanol, and stir until homogeneous to form a mixed solution. Adjust the pH of the solution to 2 with 2 mol / mL hydrochloric acid to form a reaction solution. Place the solution under nitrogen protection and react at 60°C for 4 hours. Distill under reduced pressure to obtain an organosilane containing double bonds. S3. Take all of the above carboxylated zirconium oxide suspension and 2 parts by weight of the above organosilane containing double bonds, mix them evenly, stir at 60℃ and 400 rpm for 2 h, centrifuge, wash, and dry to obtain modified zirconium oxide.

[0030] Example 2 A method for preparing a high-transmittance, high-temperature resistant acrylic optical adhesive includes the following steps: (1) Under nitrogen protection, 60 parts by weight of methyl methacrylate, 10 parts by weight of methacrylic acid, 40 parts by weight of glycidyl methacrylate, 10 parts by weight of hydroxyethyl methacrylate, 5 parts by weight of 2-hydroxy-2-methyl-1-phenyl-1-propanone and 3 parts by weight of modified silica were stirred at 85°C and 200 rpm for 8 h to obtain a gel solution. (2) Place the above adhesive liquid in a vacuum drying oven at 75°C for 12 minutes to cure it into an adhesive material. Then press the adhesive material into a sheet film and cool it to obtain a high-transmittance high-temperature resistant acrylic optical adhesive.

[0031] The modified silica is prepared as follows: S1. Add 6 parts by weight of nano-silica to 200 parts by weight of 3 g / mL adipic acid ethanol solution, stir at 75℃ and 500 rpm for 3 h, place in an ice bath, and ultrasonically disperse at ultrasonic power of 260 W and ultrasonic frequency of 40 kHz for 4 h to obtain carboxylated silica suspension. S2. Mix 5 parts by weight of γ-aminopropyltriethoxysilane, 5 parts by weight of 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane, and 6 parts by weight of vinyltrimethoxysilane, add 10 parts by weight of water and 80 parts by weight of anhydrous ethanol, and stir until homogeneous to form a mixed solution; adjust the pH of the solution to 2.8 with 1 mol / mL hydrochloric acid to form a reaction solution; place under nitrogen protection and react at 50°C for 6 h; distill under reduced pressure to obtain an organosilanes containing double bonds; S3. Take all of the above carboxylated silica suspension and 3 parts by weight of the above organosilane containing double bonds, mix them evenly, stir at 70°C and 300 rpm for 3 hours, centrifuge, wash, and dry to obtain modified silica.

[0032] Example 3 A method for preparing a high-transmittance, high-temperature resistant acrylic optical adhesive includes the following steps: (1) Under nitrogen protection, 80 parts by weight of borneol methacrylate, 5 parts by weight of methacrylic acid, 40 parts by weight of glycidyl methacrylate, 5 parts by weight of 3-hydroxypropyl methacrylate, 2 parts by weight of 1-hydroxycyclohexylphenyl ketone and 5 parts by weight of modified zirconium oxide were stirred at 60°C and 500 rpm for 8 hours to obtain a gel. (2) Place the above adhesive liquid in a vacuum drying oven at 50°C for 15 minutes to cure it into an adhesive material. Then press the adhesive material into a sheet film and cool it to obtain a high-transmittance high-temperature resistant acrylic optical adhesive.

[0033] The modified titanium dioxide is prepared as follows: S1. Add 2 parts by weight of nano titanium dioxide to 100 parts by weight of 1 g / mL adipic acid ethanol solution, stir at 55℃ and 600 rpm for 3 h, place in an ice bath, and ultrasonically disperse at ultrasonic power of 150 W and ultrasonic frequency of 50 kHz for 1 h to obtain carboxylated titanium dioxide suspension. S2. Mix 2 parts by weight of aminoethylaminoisobutylmethyldimethoxysilane, 2 parts by weight of N-(3-acryloyloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane, and 3 parts by weight of 3-(methacryloyloxy)propyltrimethoxysilane. Add 5 parts by weight of water and 40 parts by weight of anhydrous ethanol, and stir until homogeneous to form a mixed solution. Adjust the pH of the solution to 1.5 with 1 mol / mL hydrochloric acid to form a reaction solution. Place the solution under nitrogen protection and react at 70°C for 2 hours. Distill under reduced pressure to obtain an organosilane containing a double bond. S3. Take all of the above carboxylated titanium dioxide suspension and 1 part by weight of the above organosilane containing double bonds, mix them evenly, stir at 50°C and 500 rpm for 1 h, centrifuge, wash, and dry to obtain modified titanium dioxide.

[0034] Comparative Example 1 It is basically the same as Example 1, except that nano-zirconia is used instead of modified zirconia.

[0035] Comparative Example 2 The method is basically the same as in Example 1, except that the modified zirconium oxide is prepared as follows: Four parts by weight of nano-zirconia were added to 150 parts by weight of an ethanol solution of 2 g / mL adipic acid. The mixture was stirred at 65 °C and 400 rpm for 1.5 h. The mixture was then placed in an ice bath and ultrasonically dispersed at an ultrasonic power of 200 W and an ultrasonic frequency of 60 kHz for 2 h. After centrifugation, washing, and drying, modified zirconia was obtained.

[0036] Comparative Example 3 The method is basically the same as in Example 1, except that the modified zirconium oxide is prepared as follows: S1. Add 4 parts by weight of nano-zirconia to 150 parts by weight of 2 g / mL adipic acid ethanol solution, stir at 65℃ and 400 rpm for 1.5 h, place in an ice bath, and ultrasonically disperse at ultrasonic power of 200 W and ultrasonic frequency of 60 kHz for 2 h to obtain carboxylated zirconia suspension. S2. Mix 6 parts by weight of aminoethylaminoisobutylmethyldimethoxysilane and 6 parts by weight of N-(3-acryloyloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane, add 8 parts by weight of water and 50 parts by weight of anhydrous ethanol, and stir until homogeneous to form a mixed solution; adjust the pH of the solution to 2 with 2 mol / mL hydrochloric acid to form a reaction solution; place under nitrogen protection and react at 60°C for 4 h; distill under reduced pressure to obtain an organosilane containing double bonds; S3. Take all of the above carboxylated zirconium oxide suspension and 2 parts by weight of the above organosilane containing double bonds, mix them evenly, stir at 60℃ and 400 rpm for 2 h, centrifuge, wash, and dry to obtain modified zirconium oxide.

[0037] Comparative Example 4 The method is basically the same as in Example 1, except that the modified zirconium oxide is prepared as follows: S1. Add 4 parts by weight of nano-zirconia to 150 parts by weight of 2 g / mL adipic acid ethanol solution, stir at 65℃ and 400 rpm for 1.5 h, place in an ice bath, and ultrasonically disperse at ultrasonic power of 200 W and ultrasonic frequency of 60 kHz for 2 h to obtain carboxylated zirconia suspension. S2. Mix 6 parts by weight of aminoethylaminoisobutylmethyldimethoxysilane and 6 parts by weight of 3-(methacryloyloxy)propyltrimethoxysilane, add 8 parts by weight of water and 50 parts by weight of anhydrous ethanol, and stir until homogeneous to form a mixed solution; adjust the pH of the solution to 2 with 2 mol / mL hydrochloric acid to form a reaction solution; place under nitrogen protection and react at 60°C for 4 h; distill under reduced pressure to obtain an organosilane containing double bonds; S3. Take all of the above carboxylated zirconium oxide suspension and 2 parts by weight of the above organosilane containing double bonds, mix them evenly, stir at 60℃ and 400 rpm for 2 h, centrifuge, wash, and dry to obtain modified zirconium oxide.

[0038] Comparative Example 5 The method is basically the same as in Example 1, except that the modified zirconium oxide is prepared as follows: S1. Add 4 parts by weight of nano-zirconia to 150 parts by weight of 2 g / mL adipic acid ethanol solution, stir at 65℃ and 400 rpm for 1.5 h, place in an ice bath, and ultrasonically disperse at ultrasonic power of 200 W and ultrasonic frequency of 60 kHz for 2 h to obtain carboxylated zirconia suspension. S2. Mix 6 parts by weight of N-(3-acryloyloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane and 6 parts by weight of 3-(methacryloyloxy)propyltrimethoxysilane, add 8 parts by weight of water and 50 parts by weight of anhydrous ethanol, and stir until homogeneous to form a mixed solution; adjust the pH of the solution to 2 with 2 mol / mL hydrochloric acid to form a reaction solution; place under nitrogen protection and react at 60°C for 4 h; distill under reduced pressure to obtain an organosilane containing double bonds; S3. Take all of the above carboxylated zirconium oxide suspension and 2 parts by weight of the above organosilane containing double bonds, mix them evenly, stir at 60℃ and 400 rpm for 2 h, centrifuge, wash, and dry to obtain modified zirconium oxide.

[0039] Comparative Example 6 The method is basically the same as in Example 1, except that the modified zirconium oxide is prepared as follows: S1. Add 4 parts by weight of nano-zirconia to 150 parts by weight of 2 g / mL adipic acid ethanol solution, stir at 65℃ and 400 rpm for 1.5 h, place in an ice bath, and ultrasonically disperse at ultrasonic power of 200 W and ultrasonic frequency of 60 kHz for 2 h to obtain carboxylated zirconia suspension. S2. Take all of the above carboxylated zirconium oxide suspension and 12 parts by weight of aminoethylaminoisobutylmethyldimethoxysilane, mix them evenly, stir at 60℃ and 400 rpm for 2 h, centrifuge, wash, and dry to obtain modified zirconium oxide.

[0040] Comparative Example 7 The method for preparing the modified zirconium oxide is as follows: S1. Add 4 parts by weight of nano-zirconia to 150 parts by weight of 2 g / mL adipic acid ethanol solution, stir at 65℃ and 400 rpm for 1.5 h, place in an ice bath, and ultrasonically disperse at ultrasonic power of 200 W and ultrasonic frequency of 60 kHz for 2 h to obtain carboxylated zirconia suspension. S2. Take all of the above carboxylated zirconium oxide suspension and 12 parts by weight of N-(3-acryloyloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane, mix them evenly, stir at 60℃ and 400 rpm for 2 h, centrifuge, wash, and dry to obtain modified zirconium oxide.

[0041] Comparative Example 8 The method for preparing the modified zirconium oxide is as follows: S1. Add 4 parts by weight of nano-zirconia to 150 parts by weight of 2 g / mL adipic acid ethanol solution, stir at 65℃ and 400 rpm for 1.5 h, place in an ice bath, and ultrasonically disperse at ultrasonic power of 200 W and ultrasonic frequency of 60 kHz for 2 h to obtain carboxylated zirconia suspension. S2. Take all of the above carboxylated zirconium oxide suspension and 12 parts by weight of 3-(methacryloyloxy)propyltrimethoxysilane, mix them evenly, stir at 60℃ and 400 rpm for 2 h, centrifuge, wash, and dry to obtain modified zirconium oxide.

[0042] Test Example 1 Transmittance test: The transmittance of visible light at 550nm was tested using a transmittance tester. The high transmittance high-temperature resistant acrylic optical adhesives prepared in Examples 1-3 and Comparative Examples 1-8 were cut into 2cm*2cm pieces, fixed with a clamp, and tested at a temperature of about 25℃. Four groups were tested in each group, and the average value was taken. The results are shown in Table 1.

[0043] High-temperature resistance performance: A high-transmittance, high-temperature resistant acrylic optical adhesive was uniformly coated onto a 75μm thick heavy release film, followed by a coating thickness of 175μm. The film was then baked at 120℃ for 3 minutes, and a 50μm thick light release film was laminated onto the adhesive surface. The film was then cured at 70℃ for 24 hours to obtain a high-transmittance, high-temperature resistant acrylic optical adhesive film. After removing the release film and removing bubbles, the film was UV-treated and allowed to stand for 1 day. It was then placed at 150℃, 0.2MPa, and 90% humidity for 14 days. The number of bubbles was then observed, in descending order: no bubbles, very few bubbles, a few bubbles, and many bubbles. The fewer bubbles, the better the high-temperature resistance performance of the optical adhesive.

[0044] Table 1. Results of light transmittance and high temperature resistance tests

[0045] Test Example 2 Peel strength test: The high-transmittance, high-temperature resistant acrylic optical adhesives prepared in Examples 1-3 and Comparative Examples 1-8 were cut into 10cm×5cm pieces and attached to a standard steel plate to make samples. According to GB / T 2792-2014 "Test method for peel strength of adhesive tape", the samples and the samples treated in a constant temperature chamber at 100℃ for 48h were subjected to 180° peel strength tests to evaluate their peel strength and high-temperature resistance. Each group was tested 4 times and the average value was taken. The results are shown in Table 2.

[0046] Table 2. Peel strength performance test results

[0047] The results above show that the high-transmittance, high-temperature resistant acrylic optical adhesive prepared by this invention has good transmittance and high-temperature resistance, as well as good peel strength. The transmittance of the optical adhesive is greater than 90%, the heat resistance temperature is greater than 150℃, the peel strength is greater than 14N / 25mm, and the peel strength after high-temperature treatment is greater than 11.8N / 25mm. Specifically, Examples 1-3 use a silane coupling agent containing double bonds to modify the nanoparticles, grafting polymerizable double bonds onto their surface. During curing, these bonds copolymerize with acrylate monomers to form chemical bonds, significantly improving the transmittance (greater than 90%) and high-temperature resistance. No bubbles are observed after treatment at 150℃, and the peel strength and high-temperature stability are superior to Comparative Examples 1-8. In contrast, Comparative Examples 1-2, without modification or only carboxylation, resulted in nanoparticle agglomeration, leading to decreased transmittance and weak interfacial bonding.

[0048] Furthermore, Comparative Examples 3-8 lacked one of the components of amino, hydroxyl, or double-bonded silane, respectively. Although their transmittance and peel strength were better than those of Comparative Examples 1-2, they were still lower than those of the Examples. This indicates that partial functional group modification alone cannot achieve full cross-linking between nanoparticles and the matrix. It is necessary to anchor carboxylated particles with amino / hydroxyl silanes and then introduce double-bonded silanes to participate in polymerization in order to simultaneously optimize dispersibility, transmittance, and mechanical properties.

Claims

1. A method for preparing a high-transmittance, high-temperature resistant acrylic optical adhesive, characterized in that, Includes the following steps: (1) Under inert gas protection, acrylate monomers, carboxyl-containing monomers, epoxy-containing monomers, hydroxyl-containing monomers, photoinitiators and modified inorganic nanoparticles are mixed and stirred at 60-90℃ and 200-600rpm for 3-8h to obtain a glue solution. (2) The adhesive liquid is vacuum cured at 50-80℃ for 5-15 minutes to form an adhesive material, and then the adhesive material is pressed into a film and cooled to obtain the optical adhesive.

2. The preparation method of the high-transmittance, high-temperature resistant acrylic optical adhesive as described in claim 1, characterized in that, The weight parts of each component in step (1) are: 60-80 parts of acrylate monomer, 5-10 parts of carboxyl monomer, 40-50 parts of epoxy monomer, 5-10 parts of hydroxyl monomer, 1-5 parts of photoinitiator, and 3-8 parts of modified inorganic nanoparticles.

3. The preparation method of the high-transmittance, high-temperature resistant acrylic optical adhesive as described in claim 1, characterized in that, The acrylate monomer is selected from at least one of borneol methacrylate, methyl methacrylate, and butyl acrylate; the carboxyl-containing monomer is acrylic acid or methacrylic acid; the epoxy-containing monomer is glycidyl methacrylate; and the hydroxyl-containing monomer is at least one of hydroxyethyl methacrylate and 3-hydroxypropyl methacrylate.

4. The method for preparing high-transmittance, high-temperature resistant acrylic optical adhesive as described in claim 1 or 2, characterized in that, The photoinitiator is any one of azobisisobutyronitrile, 2-hydroxy-2-methyl-1-phenyl-1-propanone, 1-hydroxycyclohexylphenyl ketone, benzoyl tert-butyl peroxide, and 2-phenylbenzyl-2-dimethylamine-1-(4-morpholinobenzylphenyl)butanone.

5. The method for preparing high-transmittance, high-temperature resistant acrylic optical adhesive as described in claim 1 or 2, characterized in that, The modified inorganic nanoparticles are inorganic nanoparticles with polymerizable double bonds on their surface, and their preparation method includes: Inorganic nanoparticles were dispersed in an organic solvent containing carboxyl groups and subjected to ultrasonic treatment to obtain a carboxylated nanoparticle suspension. A silane coupling agent containing amino and / or alkoxy groups is mixed with a silane coupling agent containing double bonds, and then hydrolyzed and condensed under acidic conditions to obtain an organosilane containing double bonds. The carboxylated nanoparticle suspension was reacted with the organosilane containing double bonds to obtain the modified inorganic nanoparticles.

6. The method for preparing high-transmittance, high-temperature resistant acrylic optical adhesive according to claim 5, characterized in that, The inorganic nanoparticles are oxide nanoparticles, including at least one of zirconium oxide, titanium dioxide, and silicon dioxide.

7. The method for preparing high-transmittance, high-temperature resistant acrylic optical adhesive according to claim 5, characterized in that, The carboxyl-containing organic solvent is an ethanol solution of a C6-C14 dicarboxylic acid with a concentration of 1-3 g / mL.

8. The method for preparing high-transmittance, high-temperature resistant acrylic optical adhesive according to claim 5, characterized in that, The amino-containing silane coupling agent is selected from at least one of aminoethylaminoisobutylmethyldimethoxysilane and γ-aminopropyltriethoxysilane; the hydroxyl-containing silane coupling agent is selected from at least one of N-(3-acryloyloxy-2-hydroxypropyl)-3-aminopropyltriethoxysilane and 3-[bis(2-hydroxyethyl)amino]propane-triethoxysilane; the double-bond-containing silane coupling agent is selected from at least one of 3-(methacryloyloxy)propyltrimethoxysilane and vinyltrimethoxysilane.

9. The method for preparing high-transmittance, high-temperature resistant acrylic optical adhesive according to claim 1 or 2, characterized in that, The vacuum curing temperature in step (2) is 55-70℃ and the time is 6-10min.

10. A high-transmittance, high-temperature resistant acrylic optical adhesive, characterized in that, Prepared by the method described in any one of claims 1-9, the light transmittance is greater than 90% and the heat resistance temperature is greater than 150℃.

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