High-refractive-index nano silicon resin optical coating and preparation method thereof

Abstract

The invention relates to the technical field of LED optical coatings, and particularly discloses a high-refractive-index nano silicon resin optical coating and a preparation method thereof.According to the high-refractive-index nano silicon resin optical coating and the preparation method thereof, a rigid fluorenyl unit with the extremely high refractive index and sulfydryl are introduced into a silicon resin main chain, meanwhile, zirconium oxide is evenly dispersed in a silicon resin system, and the refractive index of a composite material is remarkably increased; octavinyl POSS is adopted as a cross-linking unit, so that the volume change is small in the coating curing process, the adhesion of the coating is enhanced, the internal stress of the coating is reduced, and the coating is prevented from cracking; eight functional groups on the POSS group provide extremely high crosslinking density, and the rigidity, compactness and thermal stability of the optical coating are significantly enhanced.

Description

Technical Field

[0001] This invention relates to the field of LED optical coating technology, specifically to a high refractive index nano-silicone resin optical coating and its preparation method. Background Technology

[0002] Organosilicon resins are a class of polymers containing Si-O bonds in their main chain. They have excellent thermal stability, weather resistance, and optical properties, and are widely used in high-temperature coatings, anti-reflective coatings, electronic adhesives, and optical coatings. As an optical coating for LED light sources, compared with epoxy resin-based LED optical coatings, silicone resin optical coatings have the advantages of better high and low temperature resistance, strong resistance to ultraviolet aging, low internal stress, and less yellowing.

[0003] In LED light sources, increasing the refractive index of the optical coating can effectively solve the problem of light loss between the LED device and the coating. Gallium nitride (GaN) is a commonly used semiconductor material in LED devices, with a high refractive index, while traditional silicone resin has a low refractive index. This significant refractive index difference causes light rays striking the optical coating from inside the LED device to be reflected at the interface, affecting the light extraction efficiency of the LED device. By increasing the refractive index of the optical coating to approach that of GaN, light loss at the interface can be effectively reduced, significantly improving the transmittance and brightness of the LED light source. Therefore, developing a silicone resin optical coating with high transmittance, high refractive index, and high reliability is crucial for promoting the development of high-performance LEDs. Summary of the Invention

[0004] The purpose of this invention is to provide a high refractive index nano-silicone resin optical coating and its preparation method, thereby improving the refractive index of the silicone resin coating and solving the problem of excessive light loss at the interface due to the large refractive index difference between the LED light source and the optical coating, which affects the luminous efficiency of the LED.

[0005] To solve the above-mentioned technical problems, the present invention provides the following technical solution:

[0006] A method for preparing a high-refractive-index nano-silicone resin optical coating, specifically comprising:

[0007] Step 1: Using bisphenol fluorene oxide, acrylic acid, and phenyltriethoxysilane as raw materials, synthesize fluorene acrylate siloxane;

[0008] Step 2: Using phenyltrimethoxysilane, diphenyldimethoxysilane and silane coupling agent KH-590 as raw materials, mercaptophenylsiloxane oligomers are synthesized;

[0009] Step 3: Using zirconium propoxide, methacrylic acid, and anhydrous ethanol as raw materials, synthesize zirconium-methacrylic acid ethanol solution;

[0010] Step 4: Using fluorenyl acrylate, mercaptophenyl siloxane oligomer, octavinyl POSS and zirconium-methacrylic acid ethanol solution as raw materials, a high refractive index nano-silicone resin slurry is synthesized, coated and dried, and cured by ultraviolet light to obtain a high refractive index nano-silicone resin optical coating.

[0011] As a limitation of the present invention, the preparation method of the acrylate fluorenylsiloxane is as follows:

[0012] Under nitrogen protection, bisphenol fluorene epoxy and acrylic acid were added to dioxane and stirred at 200-300 rpm for 20-30 min. Triphenylphosphine catalyst and p-hydroxyanisole polymerization inhibitor were added, and the reaction was carried out at 80-90℃ and 400-500 rpm for 5-6 h. After the reaction was completed, the mixture was cooled to room temperature, neutralized with saturated sodium bicarbonate aqueous solution, separated, the organic phase was washed with deionized water, dried with anhydrous magnesium sulfate, filtered, the solvent was removed by vacuum distillation, and the mixture was dried under vacuum at 40-50℃ for 3-4 h to obtain bisphenol fluorene epoxy acrylate.

[0013] Under nitrogen protection, bisphenol fluorene epoxy acrylate and phenyltriethoxysilane were added to dioxane and stirred at 200-300 rpm for 20-30 min. Then, dibutyltin dilaurate catalyst and p-hydroxyanisole polymerization inhibitor were added. The reaction was carried out at 80-90℃ and 400-500 rpm for 5-6 h. After the reaction was completed, the mixture was cooled and the solvent was removed by vacuum distillation to obtain fluorene acrylate siloxane.

[0014] As a limitation of the present invention, the mass ratio of the epoxy bisphenol fluorene, acrylic acid, triphenylphosphine and p-hydroxyanisole is (20-30):(8-12):(0.3-0.5):(0.05-0.15); the mass ratio of bisphenol fluorene epoxy acrylate, phenyltriethoxysilane, dibutyltin dilaurate and p-hydroxyanisole is (20-30):(4-8):(0.1-0.3):(0.02-0.05).

[0015] Under the catalysis of triphenylphosphine, the carboxyl group of acrylic acid is deprotonated to form a carboxylate ion, which undergoes a ring-opening reaction with the epoxy group of bisphenol fluorene to generate an ester bond and a secondary hydroxyl group, yielding bisphenol fluorene acrylate. The generated secondary hydroxyl group reacts with the alkoxysilane of phenyltriethoxysilane under the action of a catalyst, removing ethanol and generating a stable Si-OC bond to connect phenyltriethoxysilane to bisphenol fluorene acrylate, forming an acrylate fluorene siloxane containing a fluorene group, an acrylate double bond, and a phenyl group in its structure.

[0016] The fluorenyl group in the acrylate fluorenylsiloxane structure is a large planar fluorenyl ring structure with high molecular polarizability and large molar volume, resulting in an extremely high molar refractive index. Introducing it as a rigid segment into the silicone resin system increases the refractive index of the silicone resin through its extremely high intrinsic molar refractive index. At the same time, its strong steric hindrance effect improves the glass transition temperature and thermal stability of the resin. The acrylate double bond serves as an active site for crosslinking, enhancing the strength, abrasion resistance, and other properties of the optical coating after crosslinking. The siloxane segment serves as a reaction site, forming a silane organic network through subsequent hydrolysis and condensation with silane oligomers. Simultaneously, as a flexible chain, it alleviates the rigidity introduced by the fluorenyl group and improves the processing fluidity of the siloxane monomer.

[0017] As a limitation of the present invention, the method for preparing the mercaptophenylsiloxane oligomer is as follows:

[0018] Under nitrogen protection, phenyltrimethoxysilane and diphenyldimethoxysilane were added to anhydrous ethanol and stirred at 200-300 rpm for 20-30 min at 25-30 °C. Then, silane coupling agent KH-590 was added, and stirring was continued for another 20-30 min. Trifluoromethanesulfonic acid aqueous solution was added dropwise in an ice-water bath at 0-5 °C, and the reaction was stirred at 400-500 rpm for 3-4 h at 50-60 °C. After the reaction was completed, the mixture was cooled to room temperature, neutralized with saturated sodium bicarbonate aqueous solution, separated, and the organic phase was washed with deionized water, dried over anhydrous magnesium sulfate, and the solvent was removed by vacuum distillation. The mixture was then dried under vacuum at 40-50 °C for 3-4 h to obtain mercaptophenylsiloxane oligomers.

[0019] As a limitation of the present invention, the mass ratio of phenyltrimethoxysilane, diphenyldimethoxysilane, silane coupling agent KH-590 and trifluoromethanesulfonic acid is (20-30):(30-40):(15-25):(1-2).

[0020] Under the catalysis of trifluoromethanesulfonic acid, three silanes, phenyltrimethoxysilane, diphenyldimethoxysilane, and silane coupling agent KH-590, undergo hydrolysis and co-condensation to form silane oligomers with a main chain composed of Si-O-Si bonds and side groups containing phenyl (from phenyltrimethoxysilane and diphenyldimethoxysilane), methyl and mercapto (from silane coupling agent KH-590).

[0021] Phenylacetyltrimethoxysilane, as a trifunctional monomer, increases the crosslinking density of the composite material, improving the coating's hardness and wear resistance. Diphenyldimethoxysilane, as the main chain segment, maintains the linear structure of the oligomer, and the diphenyl group provides a higher molar refractive index than the monophenyl group, thereby improving the refractive index of the optical coating. Silane coupling agent KH-590, as a difunctional monomer, introduces thiol groups and flexible chains. On the one hand, sulfur atoms possess extremely high molar refractive indices, improving the refractive index of the optical coating; on the other hand, thiol groups participate in the thiol-ene click reaction, promoting rapid crosslinking and curing of the optical coating. In addition, the flexible chain structure alleviates the rigidity caused by phenyl and diphenyl groups, improving the processing fluidity of the silane oligomer.

[0022] As a limitation of the present invention, the preparation method of the zirconium-methacrylic acid ethanol solution is as follows:

[0023] Under nitrogen protection and an ice-water bath at 0-5°C, zirconium propoxide was added dropwise to methacrylic acid, and the mixture was stirred at 200-300 rpm for 20-30 min. Anhydrous ethanol was then added to obtain a zirconium-methacrylic acid ethanol solution.

[0024] As a limitation of the present invention, the mass ratio of zirconium propoxide, methacrylic acid and anhydrous ethanol is (20-30):(30-40):(28-32).

[0025] The carboxyl groups of methacrylic acid coordinate with the zirconium ions of zirconium propoxide to form a stable organic zirconium complex. Upon heating, this organic zirconium complex undergoes alcoholysis condensation, forming a Zr-O-Zr inorganic network. Using alcoholysis instead of hydrolysis slows down the formation rate of the inorganic network, making the curing and crosslinking process of the inorganic network more compatible with the silicone resin system. This avoids agglomeration or phase separation caused by excessively rapid condensation of the inorganic network, ensuring that the in-situ condensed zirconium nanoclusters are uniformly dispersed in the silicone resin system. Zirconia, a high-refractive-index (approximately 2.1) inorganic material, when uniformly dispersed in the silicone resin system, significantly improves the refractive index of the composite material. The nanoscale uniform dispersion reduces light scattering, ensuring the transparency of the composite material. The acrylate groups on the complex participate in crosslinking, enhancing the compatibility and stress transfer between the organic and inorganic phases, and improving the strength and thermal stability of the optical coating.

[0026] As a limitation of the present invention, the preparation method of the high refractive index nano-silicone resin optical coating is as follows:

[0027] Under light-protected conditions, fluorenyl acrylate, mercaptophenyl siloxane oligomer, octavinyl POSS and zirconium-methacrylic acid ethanol solution were mixed and stirred at 200-300 rpm for 20-30 min at 25-30℃. Photoinitiator TPO, photoinitiator 184 and leveling agent BYK-333 were added and stirred at 1000-1200 rpm for 3-5 min. Vacuum degassing was carried out at (-0.08)-(-0.09) MPa for 5-10 min to obtain high refractive index nano-silicone resin slurry.

[0028] Under nitrogen protection, the high refractive index nano-silicone resin slurry is coated and dried at a temperature of 80-90℃ for 5-10 minutes. After drying, it is cured by irradiation with 365nm UV light for 2-4 minutes to obtain a high refractive index nano-silicone resin optical coating.

[0029] As a limitation of the present invention, the high refractive index nano-silicone resin slurry comprises, by weight: 90-100 parts of acrylate fluorenylsiloxane, 20-30 parts of mercaptophenylsiloxane oligomer, 12-16 parts of octavinyl POSS, 130-150 parts of zirconium-methacrylate ethanol solution, 3.5-4.5 parts of photoinitiator TPO, 1.5-2.5 parts of photoinitiator 184, and 0.5-1 part of leveling agent BYK-333.

[0030] Under the action of free radicals generated by the photoinitiator, the thiol groups on the mercaptophenylsiloxane oligomer are activated, generating sulfur free radicals (·S). - The POSS group undergoes an addition reaction with the vinyl double bond on the octavinyl POSS to form a thioether bond. The POSS-based structure has a high molar refractive index, which enhances the refractive index of the optical coating. As a large-volume crosslinking unit, the POSS-based structure has a small volume change during the coating curing process, which helps to enhance the adhesion of the coating, reduce the internal stress of the coating, and prevent the coating from cracking. The eight functional groups on the POSS group provide extremely high crosslinking density, which significantly enhances the rigidity, density, and thermal stability of the optical coating.

[0031] A high-refractive-index nano-silicone resin optical coating is prepared by any of the preparation methods described above.

[0032] Compared with the prior art, the beneficial effects of the present invention are:

[0033] This invention introduces rigid fluorene units with extremely high refractive index into the main chain of silicone resin. By increasing the intrinsic molar refractive index of the silicone resin, the refractive index of the silicone resin is improved. At the same time, the mercapto groups and acrylate double bonds are evenly distributed in the silicone resin, ensuring the formation of a crosslinking network with uniform crosslinking density. This improves the uniformity of coating curing, avoids local crosslinking caused by differences in crosslinking rate, which can lead to increased internal stress and cracking of the coating, prevents phase separation, and improves the overall performance of the coating.

[0034] This invention employs a non-hydrolyzable sol-gel method to introduce zirconium oxide into a silicone resin system. Zirconium oxide is an inorganic material with a high refractive index (approximately 2.1). When uniformly dispersed in the silicone resin system, it significantly improves the refractive index of the composite material. The nanoscale uniform dispersion reduces light scattering and ensures the transparency of the composite material.

[0035] This invention uses octavinyl POSS as a crosslinking unit, which has a small volume change during the coating curing process, which helps to enhance the adhesion of the coating, reduce the internal stress of the coating, and prevent the coating from cracking. The eight functional groups on the POSS group provide extremely high crosslinking density, which significantly enhances the rigidity, density and thermal stability of the optical coating. Detailed Implementation

[0036] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. The terminology used in the embodiments is for describing specific implementation schemes, not for limiting the scope of protection of the present invention. The dosages in the embodiments are laboratory-scale tests and can be scaled up proportionally. 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.

[0037] Example 1: A method for preparing a high refractive index nano-silicone resin optical coating, specifically as follows:

[0038] Step 1: Under nitrogen protection, 20g of epoxy bisphenol fluorene and 8g of acrylic acid were added to 200mL of dioxane and stirred at 200rpm for 30min. 0.4g of catalyst triphenylphosphine and 0.1g of polymerization inhibitor p-hydroxyanisole were added and the mixture was stirred at 90℃ and 400rpm for 5h. After the reaction was completed, the mixture was cooled to room temperature, neutralized with saturated sodium bicarbonate aqueous solution, separated, and the organic phase was washed with deionized water, dried with anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum distillation. The mixture was then dried under vacuum at 40℃ for 4h to obtain bisphenol fluorene epoxy acrylate.

[0039] Step 2: Under nitrogen protection, 20g of bisphenol fluorene epoxy acrylate and 4g of phenyltriethoxysilane were added to 200mL of dioxane and stirred at 200rpm for 30min. Then, 0.2g of dibutyltin dilaurate catalyst and 0.02g of p-hydroxyanisole polymerization inhibitor were added. The mixture was stirred at 90℃ and 400rpm for 6h. After the reaction was completed, the mixture was cooled and the solvent was removed by vacuum distillation to obtain fluorene acrylate siloxane.

[0040] Step 3: Under nitrogen protection, 20g of phenyltrimethoxysilane and 30g of diphenyldimethoxysilane were added to 150mL of anhydrous ethanol. The mixture was stirred at 30℃ and 200rpm for 30min. Then, 15g of silane coupling agent KH-590 was added, and the mixture was stirred for another 30min. In an ice-water bath at 0℃, 10mL of trifluoromethanesulfonic acid aqueous solution (containing 1g of trifluoromethanesulfonic acid) was added dropwise. The mixture was stirred at 50℃ and 400rpm for 3h. After the reaction was completed, the mixture was cooled to room temperature, neutralized with saturated sodium bicarbonate aqueous solution, separated, and the organic phase was washed with deionized water, dried with anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum distillation. The mixture was then dried under vacuum at 40℃ for 4h to obtain mercaptophenylsiloxane oligomers.

[0041] Step 4: Under nitrogen protection and 0℃ ice-water bath conditions, 10g of zirconium n-propoxide was added dropwise to 20g of methacrylic acid, and the mixture was stirred at 300rpm for 30min. Then, 24g of anhydrous ethanol was added to obtain a zirconium-methacrylic acid ethanol solution.

[0042] Step 5: Under light-protected conditions, mix 90g of fluorenyl acrylate siloxane, 20g of mercaptophenyl siloxane oligomer, 12g of octavinyl POSS with 130g of zirconium-methacrylic acid ethanol solution, stir at 200rpm for 30min at 25℃, add 3.5g of photoinitiator TPO, 1.5g of photoinitiator 184 and 0.5g of leveling agent BYK-333, stir at 1000rpm for 5min, and degas under vacuum at -0.09MPa for 10min to obtain a high refractive index nano-silicone resin slurry;

[0043] Step 6: Under nitrogen protection, the high refractive index nano-silicone resin slurry is coated and dried at 80℃ for 5 minutes. After drying, it is cured by irradiation with 365nm UV light for 2 minutes to obtain a high refractive index nano-silicone resin optical coating.

[0044] Example 2: A method for preparing a high-refractive-index nano-silicone resin optical coating, specifically as follows:

[0045] Step 1: Under nitrogen protection, 25g of epoxy bisphenol fluorene and 10g of acrylic acid were added to 200mL of dioxane and stirred at 200rpm for 30min. 0.4g of catalyst triphenylphosphine and 0.1g of polymerization inhibitor p-hydroxyanisole were added and the mixture was stirred at 90℃ and 400rpm for 5h. After the reaction was completed, the mixture was cooled to room temperature, neutralized with saturated sodium bicarbonate aqueous solution, separated, and the organic phase was washed with deionized water, dried with anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum distillation. The mixture was then dried under vacuum at 40℃ for 4h to obtain bisphenol fluorene epoxy acrylate.

[0046] Step 2: Under nitrogen protection, 25g of bisphenol fluorene epoxy acrylate and 6g of phenyltriethoxysilane were added to 200mL of dioxane and stirred at 200rpm for 30min. Then, 0.2g of dibutyltin dilaurate catalyst and 0.02g of p-hydroxyanisole polymerization inhibitor were added. The mixture was stirred at 90℃ and 400rpm for 6h. After the reaction was completed, the mixture was cooled and the solvent was removed by vacuum distillation to obtain fluorene acrylate siloxane.

[0047] Step 3: Under nitrogen protection, 25g of phenyltrimethoxysilane and 35g of diphenyldimethoxysilane were added to 150mL of anhydrous ethanol. The mixture was stirred at 30℃ and 200rpm for 30min. Then, 20g of silane coupling agent KH-590 was added, and the mixture was stirred for another 30min. In an ice-water bath at 0℃, 10mL of trifluoromethanesulfonic acid aqueous solution (containing 1g of trifluoromethanesulfonic acid) was added dropwise. The mixture was stirred at 50℃ and 400rpm for 3h. After the reaction was completed, the mixture was cooled to room temperature, neutralized with saturated sodium bicarbonate aqueous solution, separated, and the organic phase was washed with deionized water, dried with anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum distillation. The mixture was then dried under vacuum at 40℃ for 4h to obtain mercaptophenylsiloxane oligomers.

[0048] Step 4: Under nitrogen protection and 0℃ ice-water bath conditions, 15g of zirconium n-propoxide was added dropwise to 25g of methacrylic acid, and the mixture was stirred at 300rpm for 30min. Then, 28g of anhydrous ethanol was added to obtain a zirconium-methacrylic acid ethanol solution.

[0049] Step 5: Under light-protected conditions, mix 95g of fluorenyl acrylate siloxane, 25g of mercaptophenyl siloxane oligomer, 14g of octavinyl POSS with 140g of zirconium-methacrylic acid ethanol solution, stir at 200 rpm for 30 min at 25°C, add 4g of photoinitiator TPO, 2g of photoinitiator 184 and 0.5g of leveling agent BYK-333, stir at 1000 rpm for 5 min, and degas under vacuum at -0.09 MPa for 10 min to obtain a high refractive index nano-silicone resin slurry;

[0050] Step 6: Under nitrogen protection, the high refractive index nano-silicone resin slurry is coated and dried at 80℃ for 5 minutes. After drying, it is cured by irradiation with 365nm UV light for 2 minutes to obtain a high refractive index nano-silicone resin optical coating.

[0051] Example 3: A method for preparing a high-refractive-index nano-silicone resin optical coating, specifically as follows:

[0052] Step 1: Under nitrogen protection, 30g of epoxy bisphenol fluorene and 12g of acrylic acid were added to 200mL of dioxane and stirred at 200rpm for 30min. 0.4g of catalyst triphenylphosphine and 0.1g of polymerization inhibitor p-hydroxyanisole were added and the mixture was stirred at 90℃ and 400rpm for 5h. After the reaction was completed, the mixture was cooled to room temperature, neutralized with saturated sodium bicarbonate aqueous solution, separated, and the organic phase was washed with deionized water, dried with anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum distillation. The mixture was then dried under vacuum at 40℃ for 4h to obtain bisphenol fluorene epoxy acrylate.

[0053] Step 2: Under nitrogen protection, 30g of bisphenol fluorene epoxy acrylate and 8g of phenyltriethoxysilane were added to 200mL of dioxane and stirred at 200rpm for 30min. Then, 0.2g of dibutyltin dilaurate catalyst and 0.02g of p-hydroxyanisole polymerization inhibitor were added. The mixture was stirred at 90℃ and 400rpm for 6h. After the reaction was completed, the mixture was cooled and the solvent was removed by vacuum distillation to obtain fluorene acrylate siloxane.

[0054] Step 3: Under nitrogen protection, 30g of phenyltrimethoxysilane and 40g of diphenyldimethoxysilane were added to 150mL of anhydrous ethanol. The mixture was stirred at 30℃ and 200rpm for 30min. Then, 25g of silane coupling agent KH-590 was added, and the mixture was stirred for another 30min. In an ice-water bath at 0℃, 10mL of trifluoromethanesulfonic acid aqueous solution (containing 1g of trifluoromethanesulfonic acid) was added dropwise. The mixture was stirred at 50℃ and 400rpm for 3h. After the reaction was completed, the mixture was cooled to room temperature, neutralized with saturated sodium bicarbonate aqueous solution, separated, and the organic phase was washed with deionized water, dried with anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum distillation. The mixture was then dried under vacuum at 40℃ for 4h to obtain mercaptophenylsiloxane oligomers.

[0055] Step 4: Under nitrogen protection and 0℃ ice-water bath conditions, 20g of zirconium n-propoxide was added dropwise to 30g of methacrylic acid, and the mixture was stirred at 300rpm for 30min. Then, 32g of anhydrous ethanol was added to obtain a zirconium-methacrylic acid ethanol solution.

[0056] Step 5: Under light-protected conditions, mix 100g of fluorenyl acrylate siloxane, 30g of mercaptophenyl siloxane oligomer, 16g of octavinyl POSS with 150g of zirconium-methacrylic acid ethanol solution, stir at 200rpm for 30min at 25℃, add 4.5g of photoinitiator TPO, 2.5g of photoinitiator 184 and 1g of leveling agent BYK-333, stir at 1000rpm for 5min, and degas under vacuum at -0.09MPa for 10min to obtain a high refractive index nano-silicone resin slurry;

[0057] Step 6: Under nitrogen protection, the high refractive index nano-silicone resin slurry is coated and dried at 80℃ for 5 minutes. After drying, it is cured by irradiation with 365nm UV light for 2 minutes to obtain a high refractive index nano-silicone resin optical coating.

[0058] Based on Example 1, the following comparative experiments were conducted, specifically Comparative Example 1, Comparative Example 2, and Comparative Example 3, as described below:

[0059] Comparative Example 1: This comparative example relates to a method for preparing a high refractive index nano-silicone resin optical coating. The difference from Example 1 is that acrylate fluorenylsiloxane is not added. Specifically:

[0060] Step 1: Under nitrogen protection, 20g of phenyltrimethoxysilane and 30g of diphenyldimethoxysilane were added to 150mL of anhydrous ethanol. The mixture was stirred at 30℃ and 200rpm for 30min. Then, 15g of silane coupling agent KH-590 was added, and the mixture was stirred for another 30min. In an ice-water bath at 0℃, 10mL of trifluoromethanesulfonic acid aqueous solution (containing 1g of trifluoromethanesulfonic acid) was added dropwise. The mixture was stirred at 50℃ and 400rpm for 3h. After the reaction was completed, the mixture was cooled to room temperature, neutralized with saturated sodium bicarbonate aqueous solution, separated, and the organic phase was washed with deionized water, dried with anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum distillation. The mixture was then dried under vacuum at 40℃ for 4h to obtain mercaptophenylsiloxane oligomers.

[0061] Step 2: Under nitrogen protection and 0℃ ice-water bath conditions, 10g of zirconium n-propoxide was added dropwise to 20g of methacrylic acid, and the mixture was stirred at 300rpm for 30min. Then, 24g of anhydrous ethanol was added to obtain a zirconium-methacrylic acid ethanol solution.

[0062] Step 3: Under light-protected conditions, mix 110g of mercaptophenylsiloxane oligomer, 12g of octavinyl POSS and 130g of zirconium-methacrylic acid ethanol solution, stir at 200rpm for 30min at 25℃, add 3.5g of photoinitiator TPO, 1.5g of photoinitiator 184 and 0.5g of leveling agent BYK-333, stir at 1000rpm for 5min, and degas under vacuum at -0.09MPa for 10min to obtain a high refractive index nano-silicone resin slurry;

[0063] Step 4: Under nitrogen protection, the high refractive index nano-silicone resin slurry is coated and dried at 80℃ for 5 minutes. After drying, it is cured by irradiation with 365nm UV light for 2 minutes to obtain a high refractive index nano-silicone resin optical coating.

[0064] Comparative Example 2: This comparative example relates to a method for preparing a high refractive index nano-silicone resin optical coating. The difference from Example 1 is that the silane coupling agent KH-590 is not added. Specifically:

[0065] Step 1: Under nitrogen protection, 20g of epoxy bisphenol fluorene and 8g of acrylic acid were added to 200mL of dioxane and stirred at 200rpm for 30min. 0.4g of catalyst triphenylphosphine and 0.1g of polymerization inhibitor p-hydroxyanisole were added and the mixture was stirred at 90℃ and 400rpm for 5h. After the reaction was completed, the mixture was cooled to room temperature, neutralized with saturated sodium bicarbonate aqueous solution, separated, and the organic phase was washed with deionized water, dried with anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum distillation. The mixture was then dried under vacuum at 40℃ for 4h to obtain bisphenol fluorene epoxy acrylate.

[0066] Step 2: Under nitrogen protection, 20g of bisphenol fluorene epoxy acrylate and 4g of phenyltriethoxysilane were added to 200mL of dioxane and stirred at 200rpm for 30min. Then, 0.2g of dibutyltin dilaurate catalyst and 0.02g of p-hydroxyanisole polymerization inhibitor were added. The mixture was stirred at 90℃ and 400rpm for 6h. After the reaction was completed, the mixture was cooled and the solvent was removed by vacuum distillation to obtain fluorene acrylate siloxane.

[0067] Step 3: Under nitrogen protection, 20g of phenyltrimethoxysilane and 30g of diphenyldimethoxysilane were added to 150mL of anhydrous ethanol. The mixture was stirred at 30℃ and 200rpm for 30min. In an ice-water bath at 0℃, 10mL of trifluoromethanesulfonic acid aqueous solution (containing 1g of trifluoromethanesulfonic acid) was added dropwise. The mixture was stirred at 50℃ and 400rpm for 3h. After the reaction was completed, the mixture was cooled to room temperature, neutralized with saturated sodium bicarbonate aqueous solution, separated, and the organic phase was washed with deionized water, dried with anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum distillation. The mixture was then dried under vacuum at 40℃ for 4h to obtain phenylsiloxane oligomers.

[0068] Step 4: Under nitrogen protection and 0℃ ice-water bath conditions, 10g of zirconium n-propoxide was added dropwise to 20g of methacrylic acid, and the mixture was stirred at 300rpm for 30min. Then, 24g of anhydrous ethanol was added to obtain a zirconium-methacrylic acid ethanol solution.

[0069] Step 5: Under light-protected conditions, mix 90g of fluorenyl acrylate siloxane, 20g of phenyl siloxane oligomer, 12g of octavinyl POSS with 130g of zirconium-methacrylic acid ethanol solution, stir at 200rpm for 30min at 25℃, add 3.5g of photoinitiator TPO, 1.5g of photoinitiator 184 and 0.5g of leveling agent BYK-333, stir at 1000rpm for 5min, and degas under vacuum at -0.09MPa for 10min to obtain a high refractive index nano-silicone resin slurry;

[0070] Step 6: Under nitrogen protection, the high refractive index nano-silicone resin slurry is coated and dried at 80℃ for 5 minutes. After drying, it is cured by irradiation with 365nm UV light for 2 minutes to obtain a high refractive index nano-silicone resin optical coating.

[0071] Comparative Example 3: This comparative example relates to a method for preparing a high-refractive-index nano-silicone resin optical coating. The difference from Example 1 is that nano-zirconia is directly added to the slurry, specifically:

[0072] Step 1: Under nitrogen protection, 20g of epoxy bisphenol fluorene and 8g of acrylic acid were added to 200mL of dioxane and stirred at 200rpm for 30min. 0.4g of catalyst triphenylphosphine and 0.1g of polymerization inhibitor p-hydroxyanisole were added and the mixture was stirred at 90℃ and 400rpm for 5h. After the reaction was completed, the mixture was cooled to room temperature, neutralized with saturated sodium bicarbonate aqueous solution, separated, and the organic phase was washed with deionized water, dried with anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum distillation. The mixture was then dried under vacuum at 40℃ for 4h to obtain bisphenol fluorene epoxy acrylate.

[0073] Step 2: Under nitrogen protection, 20g of bisphenol fluorene epoxy acrylate and 4g of phenyltriethoxysilane were added to 200mL of dioxane and stirred at 200rpm for 30min. Then, 0.2g of dibutyltin dilaurate catalyst and 0.02g of p-hydroxyanisole polymerization inhibitor were added. The mixture was stirred at 90℃ and 400rpm for 6h. After the reaction was completed, the mixture was cooled and the solvent was removed by vacuum distillation to obtain fluorene acrylate siloxane.

[0074] Step 3: Under nitrogen protection, 20g of phenyltrimethoxysilane and 30g of diphenyldimethoxysilane were added to 150mL of anhydrous ethanol. The mixture was stirred at 30℃ and 200rpm for 30min. Then, 15g of silane coupling agent KH-590 was added, and the mixture was stirred for another 30min. In an ice-water bath at 0℃, 10mL of trifluoromethanesulfonic acid aqueous solution (containing 1g of trifluoromethanesulfonic acid) was added dropwise. The mixture was stirred at 50℃ and 400rpm for 3h. After the reaction was completed, the mixture was cooled to room temperature, neutralized with saturated sodium bicarbonate aqueous solution, separated, and the organic phase was washed with deionized water, dried with anhydrous magnesium sulfate, filtered, and the solvent was removed by vacuum distillation. The mixture was then dried under vacuum at 40℃ for 4h to obtain mercaptophenylsiloxane oligomers.

[0075] Step 4: Under light-protected conditions, mix 90g of fluorenyl acrylate siloxane, 20g of mercaptophenyl siloxane oligomer, 12g of octavinyl POSS and 25g of nano-zirconia, stir at 200rpm for 30min at 25℃, add 3.5g of photoinitiator TPO, 1.5g of photoinitiator 184 and 0.5g of leveling agent BYK-333, stir at 1000rpm for 5min, and degas under vacuum at -0.09MPa for 10min to obtain a high refractive index nano-silicone resin slurry;

[0076] Step 5: Under nitrogen protection, the high refractive index nano-silicone resin slurry is coated and dried at 80℃ for 5 minutes. After drying, it is cured by irradiation with 365nm UV light for 2 minutes to obtain a high refractive index nano-silicone resin optical coating.

[0077] Testing experiment:

[0078] High-refractive-index nano-silicone resin optical coatings were prepared as samples according to the preparation methods of each embodiment and comparative example, and the light transmittance, refractive properties and surface hardness of the coatings were tested.

[0079] Light transmittance test: The light transmittance test of the silicone resin optical coating is conducted in accordance with the "Determination of Light Transmittance and Haze of Transparent Plastics" (GB / T 2410-2008). The test light source is the CIE standard C light source, and the wavelength is 450nm blue light. The light transmittance and haze of the test sample are tested. Each sample is tested 3 times, and the average value is taken.

[0080] Refractive property test: The refractive properties of the silicone resin optical coating were tested using an Abbe refractometer at a test temperature of 25℃. The contact medium was bromonaphthalene. The refractive index of the test sample was measured. Each sample was tested three times, and the average value of the results was taken.

[0081] Surface hardness test: The surface hardness test of silicone resin optical coating is conducted in accordance with the "Determination of Hardness of Paints and Varnishes by Pencil Method" (GB / T 6739-2022). The test pencil is held at a 45° angle to the sample surface, the sliding speed is 1 mm / s, the sliding distance is 7 mm, and each hardness grade is tested 3 times to test the surface hardness of the sample.

[0082]

[0083] Conclusion: The test data shows that in Comparative Examples 1 and 2, the optical coatings prepared without the introduction of silane fluorenyl and mercapto groups respectively have lower refractive indices than those in the Examples. In Comparative Example 3, nano-zirconia was directly added to the slurry, but its dispersibility in the optical coating was not as good as in the Examples. Some trace agglomerates and larger nano-zirconia particles reduced the light transmittance of the optical coating and caused light scattering, resulting in the refractive index of the optical coating in Comparative Example 3 being much lower than that in the Examples. The high refractive index nano-silicone resin optical coatings prepared in the Examples have higher light transmittance, refractive index, and surface hardness than the Comparative Examples, and lower haze. The high refractive index nano-silicone resin coatings provided by the present invention have good light transmittance, high refractive index, and surface hardness.

[0084] It will be apparent to those skilled in the art that the present invention is not limited to the details of the exemplary embodiments described above, and that the invention can be implemented in other specific forms without departing from the spirit or essential characteristics of the invention. Therefore, the embodiments should be considered in all respects as exemplary and non-limiting, and the scope of the invention is defined by the appended claims rather than the foregoing description. Thus, it is intended that all variations falling within the meaning and scope of equivalents of the claims be included within the present invention.

Claims

1. A method for preparing a high-refractive-index nano-silicone resin optical coating, characterized in that: Specifically: Step 1: Using bisphenol fluorene oxide, acrylic acid, and phenyltriethoxysilane as raw materials, fluorene acrylate siloxane is synthesized. Step 2: Using phenyltrimethoxysilane, diphenyldimethoxysilane and silane coupling agent KH-590 as raw materials, mercaptophenylsiloxane oligomers are synthesized; Step 3: Using zirconium propoxide, methacrylic acid, and anhydrous ethanol as raw materials, synthesize zirconium-methacrylic acid ethanol solution; Step 4: Using fluorenyl acrylate, mercaptophenyl siloxane oligomer, octavinyl POSS and zirconium-methacrylic acid ethanol solution as raw materials, a high refractive index nano-silicone resin slurry is synthesized, coated and dried, and cured by ultraviolet light to obtain a high refractive index nano-silicone resin optical coating.

2. The method for preparing a high refractive index nano-silicone resin optical coating according to claim 1, characterized in that: The preparation method of fluorenyl siloxane acrylate is as follows: Under nitrogen protection, bisphenol fluorene epoxy and acrylic acid were added to dioxane and stirred at 200-300 rpm for 20-30 min. Triphenylphosphine catalyst and p-hydroxyanisole polymerization inhibitor were added, and the reaction was carried out at 80-90℃ and 400-500 rpm for 5-6 h. After the reaction was completed, the mixture was cooled to room temperature, neutralized with saturated sodium bicarbonate aqueous solution, separated, the organic phase was washed with deionized water, dried with anhydrous magnesium sulfate, filtered, the solvent was removed by vacuum distillation, and the mixture was dried under vacuum at 40-50℃ for 3-4 h to obtain bisphenol fluorene epoxy acrylate. Under nitrogen protection, bisphenol fluorene epoxy acrylate and phenyltriethoxysilane were added to dioxane and stirred at 200-300 rpm for 20-30 min. Then, dibutyltin dilaurate catalyst and p-hydroxyanisole polymerization inhibitor were added. The reaction was carried out at 80-90℃ and 400-500 rpm for 5-6 h. After the reaction was completed, the mixture was cooled and the solvent was removed by vacuum distillation to obtain fluorene acrylate siloxane.

3. The method for preparing a high refractive index nano-silicone resin optical coating according to claim 2, characterized in that: The mass ratio of bisphenol fluorene epoxy, acrylic acid, triphenylphosphine and p-hydroxyanisole is (20-30):(8-12):(0.3-0.5):(0.05-0.15); the mass ratio of bisphenol fluorene epoxy acrylate, phenyltriethoxysilane, dibutyltin dilaurate and p-hydroxyanisole is (20-30):(4-8):(0.1-0.3):(0.02-0.05).

4. The method for preparing a high refractive index nano-silicone resin optical coating according to claim 1, characterized in that: The preparation method of mercaptophenylsiloxane oligomers is as follows: Under nitrogen protection, phenyltrimethoxysilane and diphenyldimethoxysilane were added to anhydrous ethanol and stirred at 200-300 rpm for 20-30 min at 25-30 °C. Then, silane coupling agent KH-590 was added, and stirring was continued for another 20-30 min. Trifluoromethanesulfonic acid aqueous solution was added dropwise in an ice-water bath at 0-5 °C, and the reaction was stirred at 400-500 rpm for 3-4 h at 50-60 °C. After the reaction was completed, the mixture was cooled to room temperature, neutralized with saturated sodium bicarbonate aqueous solution, separated, and the organic phase was washed with deionized water, dried over anhydrous magnesium sulfate, and the solvent was removed by vacuum distillation. The mixture was then dried under vacuum at 40-50 °C for 3-4 h to obtain mercaptophenylsiloxane oligomers.

5. The method for preparing a high refractive index nano-silicone resin optical coating according to claim 4, characterized in that: The mass ratio of phenyltrimethoxysilane, diphenyldimethoxysilane, silane coupling agent KH-590 and trifluoromethanesulfonic acid is (20-30):(30-40):(15-25):(1-2).

6. The method for preparing a high refractive index nano-silicone resin optical coating according to claim 1, characterized in that: The preparation method of zirconium-methacrylic acid ethanol solution is as follows: Under nitrogen protection and in an ice-water bath at 0-5°C, zirconium propoxide was added dropwise to methacrylic acid, and the mixture was stirred at 200-300 rpm for 20-30 min. Anhydrous ethanol was then added to obtain a zirconium-methacrylic acid ethanol solution.

7. The method for preparing a high refractive index nano-silicone resin optical coating according to claim 6, characterized in that: The mass ratio of zirconium propoxide, methacrylic acid and anhydrous ethanol is (20-30):(30-40):(28-32).

8. The method for preparing a high refractive index nano-silicone resin optical coating according to claim 1, characterized in that: The preparation method of high refractive index nano-silicone resin optical coating is as follows: Under light-protected conditions, fluorenyl acrylate, mercaptophenyl siloxane oligomer, octavinyl POSS and zirconium-methacrylic acid ethanol solution were mixed and stirred at 200-300 rpm for 20-30 min at 25-30℃. Photoinitiator TPO, photoinitiator 184 and leveling agent BYK-333 were added and stirred at 1000-1200 rpm for 3-5 min. Vacuum degassing was carried out at (-0.08)-(-0.09) MPa for 5-10 min to obtain high refractive index nano-silicone resin slurry. Under nitrogen protection, the high refractive index nano-silicone resin slurry is coated and dried at a temperature of 80-90℃ for 5-10 minutes. After drying, it is cured by irradiation with 365nm UV light for 2-4 minutes to obtain a high refractive index nano-silicone resin optical coating.

9. The method for preparing a high refractive index nano-silicone resin optical coating according to claim 8, characterized in that: By weight, the high refractive index nano-silicone resin slurry comprises: 90-100 parts of acrylate fluorenylsiloxane, 20-30 parts of mercaptophenylsiloxane oligomer, 12-16 parts of octavinyl POSS, 130-150 parts of zirconium-methacrylic acid ethanol solution, 3.5-4.5 parts of photoinitiator TPO, 1.5-2.5 parts of photoinitiator 184, and 0.5-1 part of leveling agent BYK-333.

10. A high-refractive-index nano-silicone resin optical coating, characterized in that: It is prepared by any one of the preparation methods according to claims 1-9.

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