A high-transmittance LED diffuser plate and its manufacturing process

Abstract

This invention provides a high-transmittance LED diffuser plate and its preparation process, belonging to the field of light diffusion materials technology. The process includes the following steps: Cerium nitrate hexahydrate, anhydrous ethanol, and triethanolamine are mixed and stirred, the supernatant is removed by centrifugation, and water, methyl methacrylate, potassium persulfate, vinyltrimethoxysilane, and 3-mercaptopropyltrimethoxysilane are added. The mixture is heated and stirred, filtered, and vacuum dried to obtain light-diffusing particles. Nanocellulose is immersed in a zinc chloride aqueous solution, then immersed in anhydrous ethanol, washed, and dried to obtain pretreated nanocellulose. The pretreated nanocellulose is added to a cyclic olefin copolymer solution and ultrasonically mixed to obtain a mixed solution. Polycarbonate and light-diffusing particles are melt-blended, extruded, stretched into strips, cooled and shaped, cut, the mixed solution is dripped in, spin-coated, and dried to obtain a high-transmittance LED diffuser plate. This invention achieves both light diffusion effect and high transmittance while maintaining a certain degree of haze.

Description

Technical Field

[0001] This invention relates to the field of light diffusion materials technology, specifically to a high-transmittance LED diffuser plate and its preparation process. Background Technology

[0002] Compared to incandescent and fluorescent lighting, LED lighting has significant advantages such as energy saving, high efficiency, small size, long lifespan, and environmental friendliness. However, due to its high brightness and concentrated light distribution, LEDs are primarily point light source characteristics, which can easily lead to glare and spotlighting issues during use.

[0003] Currently, most solutions to the glare problem of LED lights involve the fabrication of LED diffuser plates. The main components of these diffuser plates are a transparent resin substrate and a small amount of light-diffusing particles. The transparent resin substrate includes polycarbonate, polymethyl methacrylate (PMMA), and polystyrene, among others. PMMA is favored in the market due to its excellent transparency, abundant availability, low cost, and good processing performance. However, the hygroscopic nature of PMMA resin can cause material warping, and its surface scratch resistance is insufficient; these shortcomings limit its application in light-diffusing materials.

[0004] The light diffusion performance of materials is mainly affected by light-diffusing particles. Adding light-diffusing particles to transparent resin increases the haze of the diffuser plate, thus converting the point light source of the LED into a soft surface light source to reduce glare. However, traditional light-diffusing particles, while increasing the haze of the diffuser plate, also significantly reduce the light transmittance, which is detrimental to the diffuser plate. Therefore, the contradiction between transmittance and haze has not been well resolved. In addition, traditional light-diffusing particles are mainly inorganic materials. Although they are inexpensive and have good heat resistance, they suffer from drawbacks such as inconsistent particle shape, large particle size deviation, and uneven light diffusion. Furthermore, inorganic particles have poor compatibility with the matrix material.

[0005] Therefore, there is a need to provide a high-transmittance LED diffuser plate and its manufacturing process to solve the problems existing in the prior art. Summary of the Invention

[0006] In view of this, the present invention provides a high-transmittance LED diffuser plate and its manufacturing process, which can achieve good light diffusion effect and high transmittance while having a certain degree of haze.

[0007] To achieve the above objectives, the present invention provides a process for manufacturing a high-transmittance LED diffuser plate, comprising the following steps:

[0008] S1. Mix cerium nitrate hexahydrate and anhydrous ethanol, add triethanolamine and stir, centrifuge to remove supernatant, add deionized water and methyl methacrylate under heating and stirring, heat up, add potassium persulfate, vinyltrimethoxysilane and 3-mercaptopropyltrimethoxysilane, heat and stir, filter, wash, and vacuum dry to obtain polymer-inorganic nanocomposite material as light diffusion particles.

[0009] S2. First, soak the nanocellulose in an aqueous solution of zinc chloride, then soak it in anhydrous ethanol, wash it, and dry it to obtain pretreated nanocellulose; add the pretreated nanocellulose to a cyclic olefin copolymer solution, and sonicate it to obtain a mixed solution.

[0010] S3. After mixing polycarbonate and light diffusion particles, melt-blend them using a twin-screw extruder, extrude them, then draw them into strips, cool and shape them, and cut them to obtain an LED diffusion plate; drop the mixed solution onto the LED diffusion plate, spin-coat it, and dry it to obtain a high-transmittance LED diffusion plate.

[0011] This invention prepares polymer-inorganic nanocomposites as light-diffusing particles; wherein cerium nitrate hexahydrate is used as the cerium source, and triethanolamine provides OH groups. - Ions and Ce 3+ Cerium hydroxide is obtained by combining and is eventually oxidized to cerium dioxide as an inorganic material in polymer-inorganic nanocomposites. Cerium dioxide has a high refractive index and good transmittance in the visible spectrum. In the matrix, cerium dioxide particles act as light scattering centers, and through multiple reflections and scattering effects, light diffuses on the surface of microspheres, thereby improving the light diffusivity of the material. Vinyltrimethoxysilane and 3-mercaptopropyltrimethoxysilane participate in graft copolymerization and hydrolysis condensation to form a siloxane coating structure as the outer layer of cerium dioxide particles. This enhances the bonding force between cerium dioxide particles and the matrix, optimizes the compatibility between particles and the matrix, and effectively improves the disadvantage of cerium dioxide turning yellow easily in optical applications.

[0012] This invention employs a surface dissolution-regeneration method to prepare a coating with high light transmittance and a certain degree of haze. The high specific surface area and unique fiber structure of nanocellulose enable it to provide significant light scattering effects. After being dissolved in zinc chloride, the nanocellulose is regenerated in ethanol, allowing the partially dissolved cellulose on the surface to regenerate into a dense cellulose film. This enhances mechanical properties while inducing light scattering and improving haze. The cyclic olefin copolymer has extremely low water absorption, high light transmittance, and strong weather resistance. The nanocellulose can be embedded in the polymer matrix, and the two work synergistically to enhance the water vapor and oxygen barrier properties.

[0013] Optionally, in step S1, the addition of triethanolamine is stirred for 40-70 minutes. After centrifugation to remove the supernatant, the mixture is heated in a water bath at a rate of 5°C / min. Deionized water and methyl methacrylate are added under electromagnetic stirring. After the temperature rises to 70°C, potassium persulfate is added, and vinyltrimethoxysilane and 3-mercaptopropyltrimethoxysilane are slowly added dropwise over 30 minutes. The mixture is stirred and reacted at 70°C for 4 hours. After filtration, the mixture is washed 3-5 times with distilled water and dried under vacuum at 60°C for 12 hours to obtain light-diffusing particles.

[0014] Optionally, in step S1, after vacuum drying, hydrogen peroxide solution is added, the mixture is heated to react, the precipitate is collected by centrifugation, dispersed in deionized water, potassium hydroxide solution is added to adjust the pH value to 12-13, the mixture is refluxed, the pH value is adjusted to 7-8 with hydrochloric acid solution, the precipitate is collected by centrifugation, and washed with methanol 2-3 times to finally obtain the polymer-inorganic nanocomposite material as light diffusion particles.

[0015] This invention utilizes hydrogen peroxide to oxidize the sulfur groups on the surface of light-diffusing particles into sulfonic acid groups. By incorporating the light-diffusing particles into the base material, it compensates for the insufficient flame retardant performance of polycarbonate alone and avoids the problem of using more flame retardants to improve flame retardant performance, which would lead to a deterioration in light diffusion performance.

[0016] Optionally, the hydrogen peroxide solution has a volume concentration of 20%, the potassium hydroxide solution has a molar concentration of 1%, and the hydrochloric acid solution has a molar concentration of 1%.

[0017] Optionally, the nanocellulose is prepared by dispersing hardwood pulp in deionized water, ball milling at 500 rpm for 80-120 min, vacuum filtering through a 0.22 μm filter membrane, and vacuum drying at 60 °C for 2 h.

[0018] This invention obtains nanocellulose from wood pulp cellulose by ball milling without the use of additional chemicals. During ball milling, the cellulose fibers are deflated, and their diameter is reduced from the micrometer level to the nanometer level, which increases the density of the nanocellulose membrane and strengthens the interaction between the fibrils, thereby improving the overall strength of the coating. Furthermore, the reduction in fiber size effectively reduces light scattering and improves the light transmittance of the nanocellulose membrane.

[0019] Optionally, the cyclic olefin copolymer solution is prepared by mixing and stirring toluene and cyclic olefin copolymer particles for 1 hour.

[0020] Optionally, the pretreated nanocellulose in step S2 is obtained by immersing nanocellulose in a 25% zinc chloride aqueous solution at 75°C for 20-50 seconds, then immersing it in anhydrous ethanol for 10-20 minutes, washing it three times with flowing ethanol, and then drying it; the ultrasonic treatment is carried out in an ice bath for 300-500 minutes.

[0021] This invention uses ethanol washing to remove residual chemicals from the surface, thus avoiding adverse effects on subsequent performance.

[0022] Optionally, the LED diffuser plate is made by mixing polycarbonate, antioxidant 1098, and light diffusion particles, then melting and blending them using a twin-screw extruder at 200~265℃ and 300~350rpm, extruding, stretching, cooling and shaping, and cutting.

[0023] In this invention, when adding polycarbonate and light-diffusing particles, antioxidant 1098 is also added to prevent polycarbonate from undergoing thermal degradation during high-temperature processing, thereby extending its service life, maintaining the mechanical properties and transparency of the material, and ensuring the stability and durability of the LED diffuser plate.

[0024] Optionally, in step S3, the spin coating speed is 250 rpm and the time is 10-15 s, and the drying temperature is 80-100℃ and the time is 1-1.5 h.

[0025] Optionally, the high-transmittance LED diffuser plate comprises the following raw materials in parts by weight: 100-120 parts polycarbonate, 1.5-3.2 parts light-diffusing particles, and 2-5 parts mixed solution.

[0026] The present invention uses the above-mentioned mass fraction matching ratio to achieve good light diffusion effect and maintain high light transmittance while further improving overall performance.

[0027] The above-described technical solution of the present invention has at least the following beneficial effects:

[0028] 1. This invention prepares a polymer-inorganic nanocomposite material as light-diffusing particles, with cerium dioxide particles acting as light-scattering centers. Through multiple reflections and scattering effects, the light diffusivity of the material is improved. The introduction of vinyltrimethoxysilane and 3-mercaptopropyltrimethoxysilane to form a siloxane coating structure enhances the bonding force and compatibility between cerium dioxide particles and the matrix, thus improving the problem of cerium dioxide's tendency to yellow in optical applications.

[0029] 2. This invention employs a surface dissolution-regeneration method to prepare a coating with high light transmittance and moderate haze. Nanocellulose provides a significant light scattering effect, and after dissolution with zinc chloride, it is regenerated in ethanol to form a dense film, improving mechanical properties and haze. Cycloolefin copolymers exhibit low water absorption and high light transmittance, as well as strong weather resistance. Nanocellulose can be effectively embedded in the polymer matrix, synergistically enhancing water vapor and oxygen barrier properties, thus optimizing the optical and physical properties of the coating. Attached Figure Description

[0030] Figure 1 The images show the scattered light of the blank sample and the sample from Example 6 of this invention. Detailed Implementation

[0031] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below in conjunction with the embodiments of the present invention. The described embodiments are some embodiments of the present invention, and all other embodiments obtained by those skilled in the art based on the described embodiments of the present invention are within the scope of protection of the present invention.

[0032] Example 1

[0033] Seven parts of cerium nitrate hexahydrate and 45 parts of anhydrous ethanol were mixed and stirred for 10 min. Then, 12 parts of triethanolamine were added and stirred at room temperature for 50 min, resulting in a brown precipitate. The supernatant was removed by centrifugation. The mixture was heated in a water bath at a rate of 5 °C / min, and 500 parts of deionized water and 15 parts of methyl methacrylate were added to the precipitate under electromagnetic stirring. After the temperature was raised to 70 °C, 0.7 parts of potassium persulfate were added, and 4 parts of vinyltrimethoxysilane and 5 parts of 3-mercaptopropyltrimethoxysilane were slowly added dropwise over 30 min. The mixture was stirred at 70 °C for 4 h, filtered, washed three times with deionized water, and dried under vacuum at 60 °C for 12 h to obtain thiofunctionalized organosilicon / CeO2 microspheres.

[0034] Five parts of thiofunctionalized organosilicon / CeO2 microspheres were dispersed in 300 parts of 20% hydrogen peroxide solution. After reacting at 60℃ for 5 h, the precipitate was collected by centrifugation and dispersed in 300 parts of deionized water. The pH value was adjusted to 12 by adding 1% potassium hydroxide solution and refluxed at 55℃ for 3 h. Then, the pH value was adjusted to 7 by adding 1% hydrochloric acid solution. The precipitate was collected by centrifugation and washed twice with methanol to obtain a polymer-inorganic nanocomposite material as light-diffusing particles.

[0035] 50 parts of hardwood pulp were dispersed in 1000 parts of deionized water, ball-milled at 500 rpm for 80 min, vacuum filtered through a 0.22 μm filter membrane, and dried in a vacuum oven at 60 °C for 2 h to obtain nanocellulose. 20 parts of nanocellulose were immersed in 100 parts of a 25% ZnCl2 aqueous solution at 75 °C for 20 s, then immersed in 100 parts of anhydrous ethanol for 10 min, washed three times with flowing ethanol, and dried at room temperature until the weight remained constant to obtain pretreated nanocellulose. 100 parts of toluene and 23 parts of cyclic olefin copolymer particles were mixed and stirred for 1 h to obtain a cyclic olefin copolymer solution. 10 parts of pretreated nanocellulose were added to 50 parts of the cyclic olefin copolymer solution and ultrasonically treated in an ice bath for 300 min to obtain a mixed solution.

[0036] 120 parts of polycarbonate, 0.3 parts of antioxidant 1098, and 1.5 parts of light diffusion particles were mixed and melt-blended using a twin-screw extruder at 200°C and 300 rpm. The mixture was then extruded, stretched, cooled, shaped, and cut to obtain an LED diffuser plate. Two parts of the prepared mixed solution were dropped onto the LED diffuser plate and spin-coated at 250 rpm for 10 seconds. The plate was then dried in an oven at 100°C for 1.5 hours to obtain a high-transmittance LED diffuser plate.

[0037] Example 2

[0038] Eight parts of cerium nitrate hexahydrate and 40 parts of anhydrous ethanol were mixed and stirred for 12 min. Then, 13 parts of triethanolamine were added and stirred at room temperature for 40 min, resulting in a brown precipitate. The supernatant was removed by centrifugation, and the mixture was heated in a water bath at a rate of 5 °C / min. Under electromagnetic stirring, 500 parts of deionized water and 16 parts of methyl methacrylate were added to the precipitate. After the temperature was raised to 70 °C, 0.9 parts of potassium persulfate were added, and 4 parts of vinyltrimethoxysilane and 5 parts of 3-mercaptopropyltrimethoxysilane were slowly added dropwise over 30 min. The mixture was stirred at 70 °C for 4 h, filtered, washed four times with deionized water, and dried under vacuum at 60 °C for 12 h to obtain thiofunctionalized organosilicon / CeO2 microspheres.

[0039] Six parts of thiofunctionalized organosilicon / CeO2 microspheres were dispersed in 300 parts of 20% hydrogen peroxide solution. After reacting at 60℃ for 7 h, the precipitate was collected by centrifugation and dispersed in 300 parts of deionized water. The pH value was adjusted to 12.5 by adding 1% potassium hydroxide solution and refluxed at 50℃ for 3 h. Then, the pH value was adjusted to 7.6 by 1% hydrochloric acid solution. The precipitate was collected by centrifugation and washed three times with methanol to obtain a polymer-inorganic nanocomposite material as light-diffusing particles.

[0040] 50 parts of hardwood pulp were dispersed in 1000 parts of deionized water, ball-milled at 500 rpm for 120 min, vacuum filtered through a 0.22 μm filter membrane, and dried in a vacuum oven at 60 °C for 2 h to obtain nanocellulose. 25 parts of nanocellulose were immersed in 100 parts of a 25% ZnCl2 aqueous solution at 75 °C for 30 s, then immersed in 100 parts of anhydrous ethanol for 15 min, washed three times with flowing ethanol, and dried at room temperature until the weight remained constant to obtain pretreated nanocellulose. 100 parts of toluene and 23 parts of cyclic olefin copolymer particles were mixed and stirred for 1 h to obtain a cyclic olefin copolymer solution. 11 parts of pretreated nanocellulose were added to 55 parts of the cyclic olefin copolymer solution and ultrasonically treated in an ice bath for 350 min to obtain a mixed solution.

[0041] 100 parts of polycarbonate, 0.4 parts of antioxidant 1098, and 2.2 parts of light diffusion particles were mixed and melt-blended using a twin-screw extruder at 245°C and 320 rpm. The mixture was then extruded, stretched, cooled, shaped, and cut to obtain an LED diffuser plate. Four parts of the prepared mixed solution were dropped onto the LED diffuser plate and spin-coated at 250 rpm for 15 seconds. The plate was then dried in an oven at 100°C for 1 hour to obtain a high-transmittance LED diffuser plate.

[0042] Example 3

[0043] 12 parts of cerium nitrate hexahydrate and 48 parts of anhydrous ethanol were mixed and stirred for 13 min. 14 parts of triethanolamine were added, and the mixture was stirred at room temperature for 70 min, resulting in a brown precipitate. The supernatant was removed by centrifugation, and the mixture was heated in a water bath at a rate of 5 °C / min. 500 parts of deionized water and 17 parts of methyl methacrylate were added to the precipitate under electromagnetic stirring. After the temperature reached 70 °C, 1.1 parts of potassium persulfate were added, and 4 parts of vinyltrimethoxysilane and 5 parts of 3-mercaptopropyltrimethoxysilane were slowly added dropwise over 30 min. The mixture was stirred at 70 °C for 4 h, filtered, washed 4 times with deionized water, and vacuum dried at 60 °C for 12 h to obtain thiofunctionalized organosilicon / CeO2 microspheres.

[0044] Seven parts of thiofunctionalized organosilicon / CeO2 microspheres were dispersed in 300 parts of 20% hydrogen peroxide solution. After reacting at 60℃ for 6 hours, the precipitate was collected by centrifugation and dispersed in 300 parts of deionized water. The pH value was adjusted to 13 by adding 1% potassium hydroxide solution and refluxed at 60℃ for 3 hours. Then, the pH value was adjusted to 8 by 1% hydrochloric acid solution. The precipitate was collected by centrifugation and washed twice with methanol to obtain a polymer-inorganic nanocomposite material as light-diffusing particles.

[0045] 50 parts of hardwood pulp were dispersed in 1000 parts of deionized water, ball-milled at 500 rpm for 100 min, vacuum filtered through a 0.22 μm filter membrane, and dried in a vacuum oven at 60 °C for 2 h to obtain nanocellulose. 30 parts of nanocellulose were immersed in 100 parts of a 25% ZnCl2 aqueous solution at 75 °C for 35 s, then immersed in 100 parts of anhydrous ethanol for 20 min, washed three times with flowing ethanol, and dried at room temperature until the weight remained constant to obtain pretreated nanocellulose. 100 parts of toluene and 23 parts of cyclic olefin copolymer particles were mixed and stirred for 1 h to obtain a cyclic olefin copolymer solution. 12 parts of pretreated nanocellulose were added to 60 parts of the cyclic olefin copolymer solution and ultrasonically treated in an ice bath for 400 min to obtain a mixed solution.

[0046] 110 parts of polycarbonate, 0.5 parts of antioxidant 1098, and 2.7 parts of light diffusion particles were mixed and melt-blended using a twin-screw extruder at 220°C and 300 rpm. The mixture was then extruded, stretched, cooled, shaped, and cut to obtain an LED diffuser plate. Three parts of the prepared mixed solution were dropped onto the LED diffuser plate and spin-coated at 250 rpm for 12 seconds. The plate was then dried in an oven at 100°C for 1.2 hours to obtain a high-transmittance LED diffuser plate.

[0047] Example 4

[0048] 12 parts of cerium nitrate hexahydrate and 48 parts of anhydrous ethanol were mixed and stirred for 15 min. 15 parts of triethanolamine were added, and the mixture was stirred at room temperature for 70 min, resulting in a brown precipitate. The supernatant was removed by centrifugation, and the mixture was heated in a water bath at a rate of 5 °C / min. 500 parts of deionized water and 18 parts of methyl methacrylate were added to the precipitate under electromagnetic stirring. After the temperature reached 70 °C, 1.2 parts of potassium persulfate were added, and 4 parts of vinyltrimethoxysilane and 5 parts of 3-mercaptopropyltrimethoxysilane were slowly added dropwise over 30 min. The mixture was stirred at 70 °C for 4 h, filtered, washed 5 times with deionized water, and vacuum dried at 60 °C for 12 h to obtain thiofunctionalized organosilicon / CeO2 microspheres.

[0049] Eight parts of thiofunctionalized organosilicon / CeO2 microspheres were dispersed in 300 parts of 20% hydrogen peroxide solution. After reacting at 60℃ for 8 hours, the precipitate was collected by centrifugation and dispersed in 300 parts of deionized water. The pH value was adjusted to 12 by adding 1% potassium hydroxide solution and refluxed at 60℃ for 3 hours. Then, the pH value was adjusted to 8 by 1% hydrochloric acid solution. The precipitate was collected by centrifugation and washed three times with methanol to obtain a polymer-inorganic nanocomposite material as light-diffusing particles.

[0050] 50 parts of hardwood pulp were dispersed in 1000 parts of deionized water, ball-milled at 500 rpm for 120 min, vacuum filtered through a 0.22 μm filter membrane, and dried in a vacuum oven at 60 °C for 2 h to obtain nanocellulose. 20 parts of nanocellulose were immersed in 100 parts of a 25% ZnCl2 aqueous solution at 75 °C for 40 s, then immersed in 100 parts of anhydrous ethanol for 20 min, washed three times with flowing ethanol, and dried at room temperature until the weight remained constant to obtain pretreated nanocellulose. 100 parts of toluene and 23 parts of cyclic olefin copolymer particles were mixed and stirred for 1 h to obtain a cyclic olefin copolymer solution. 10 parts of pretreated nanocellulose were added to 65 parts of the cyclic olefin copolymer solution and ultrasonically treated in an ice bath for 500 min to obtain a mixed solution.

[0051] 100 parts of polycarbonate, 0.3 parts of antioxidant 1098, and 2.4 parts of light diffusion particles were mixed and melt-blended using a twin-screw extruder at 230°C and 350 rpm. The mixture was then extruded, stretched, cooled, shaped, and cut to obtain an LED diffuser plate. Five parts of the prepared mixed solution were dropped onto the LED diffuser plate and spin-coated at 250 rpm for 15 seconds. The plate was then dried in an oven at 100°C for 1.5 hours to obtain a high-transmittance LED diffuser plate.

[0052] Example 5

[0053] 13 parts of cerium nitrate hexahydrate and 40 parts of anhydrous ethanol were mixed and stirred for 15 min. 12 parts of triethanolamine were added, and the mixture was stirred at room temperature for 60 min, resulting in a brown precipitate. The supernatant was removed by centrifugation, and the mixture was heated in a water bath at a rate of 5 °C / min. 500 parts of deionized water and 15 parts of methyl methacrylate were added to the precipitate under electromagnetic stirring. After the temperature was raised to 70 °C, 0.7 parts of potassium persulfate were added, and 4 parts of vinyltrimethoxysilane and 5 parts of 3-mercaptopropyltrimethoxysilane were slowly added dropwise over 30 min. The mixture was stirred at 70 °C for 4 h, filtered, washed 4 times with deionized water, and vacuum dried at 60 °C for 12 h to obtain thiofunctionalized organosilicon / CeO2 microspheres.

[0054] Eight parts of thiofunctionalized organosilicon / CeO2 microspheres were dispersed in 300 parts of 20% hydrogen peroxide solution. After reacting at 60℃ for 5 h, the precipitate was collected by centrifugation and dispersed in 300 parts of deionized water. The pH value was adjusted to 12 by adding 1% potassium hydroxide solution and refluxed at 50℃ for 3 h. Then, the pH value was adjusted to 7.5 by 1% hydrochloric acid solution. The precipitate was collected by centrifugation and washed twice with methanol to obtain a polymer-inorganic nanocomposite material as light-diffusing particles.

[0055] 50 parts of hardwood pulp were dispersed in 1000 parts of deionized water, ball-milled at 500 rpm for 90 min, vacuum filtered through a 0.22 μm filter membrane, and dried in a vacuum oven at 60 °C for 2 h to obtain nanocellulose. 30 parts of nanocellulose were immersed in 100 parts of a 25% ZnCl2 aqueous solution at 75 °C for 20 s, then immersed in 100 parts of anhydrous ethanol for 15 min, washed three times with flowing ethanol, and dried at room temperature until the weight remained constant to obtain pretreated nanocellulose. 100 parts of toluene and 23 parts of cyclic olefin copolymer particles were mixed and stirred for 1 h to obtain a cyclic olefin copolymer solution. 12 parts of pretreated nanocellulose were added to 50 parts of the cyclic olefin copolymer solution and ultrasonically treated in an ice bath for 500 min to obtain a mixed solution.

[0056] 100 parts of polycarbonate, 0.4 parts of antioxidant 1098, and 3 parts of light diffusion particles were mixed and melt-blended using a twin-screw extruder at 265°C and 300 rpm. The mixture was then extruded, stretched, cooled, shaped, and cut to obtain an LED diffuser plate. Two parts of the prepared mixed solution were dropped onto the LED diffuser plate and spin-coated at 250 rpm for 10 seconds. The plate was then dried in an oven at 100°C for 1 hour to obtain a high-transmittance LED diffuser plate.

[0057] Example 6

[0058] 13 parts of cerium nitrate hexahydrate and 50 parts of anhydrous ethanol were mixed and stirred for 15 min. 15 parts of triethanolamine were added, and the mixture was stirred at room temperature for 70 min, resulting in a brown precipitate. The supernatant was removed by centrifugation, and the mixture was heated in a water bath at a rate of 5 °C / min. 500 parts of deionized water and 18 parts of methyl methacrylate were added to the precipitate under electromagnetic stirring. After the temperature reached 70 °C, 1.2 parts of potassium persulfate were added, and 4 parts of vinyltrimethoxysilane and 5 parts of 3-mercaptopropyltrimethoxysilane were slowly added dropwise over 30 min. The mixture was stirred at 70 °C for 4 h, filtered, washed 5 times with deionized water, and vacuum dried at 60 °C for 12 h to obtain thiofunctionalized organosilicon / CeO2 microspheres.

[0059] Eight parts of thiofunctionalized organosilicon / CeO2 microspheres were dispersed in 300 parts of 20% hydrogen peroxide solution. After reacting at 60℃ for 8 hours, the precipitate was collected by centrifugation and dispersed in 300 parts of deionized water. The pH value was adjusted to 13 by adding 1% potassium hydroxide solution and refluxed at 50℃ for 3 hours. Then, the pH value was adjusted to 8 by 1% hydrochloric acid solution. The precipitate was collected by centrifugation and washed three times with methanol to obtain a polymer-inorganic nanocomposite material as light-diffusing particles.

[0060] 50 parts of hardwood pulp were dispersed in 1000 parts of deionized water, ball-milled at 500 rpm for 110 min, vacuum filtered through a 0.22 μm filter membrane, and dried in a vacuum oven at 60 °C for 2 h to obtain nanocellulose. 30 parts of nanocellulose were immersed in 100 parts of a 25% ZnCl2 aqueous solution at 75 °C for 50 s, then immersed in 100 parts of anhydrous ethanol for 20 min, washed three times with flowing ethanol, and dried at room temperature until the weight remained constant to obtain pretreated nanocellulose. 100 parts of toluene and 23 parts of cyclic olefin copolymer particles were mixed and stirred for 1 h to obtain a cyclic olefin copolymer solution. 12 parts of pretreated nanocellulose were added to 65 parts of the cyclic olefin copolymer solution and ultrasonically treated in an ice bath for 300 min to obtain a mixed solution.

[0061] 120 parts of polycarbonate, 0.5 parts of antioxidant 1098, and 3.2 parts of light diffusion particles were mixed and melt-blended using a twin-screw extruder at 265°C and 350 rpm. The mixture was then extruded, stretched, cooled, shaped, and cut to obtain an LED diffuser plate. Five parts of the prepared mixed solution were dropped onto the LED diffuser plate and spin-coated at 250 rpm for 15 seconds. The plate was then dried in an oven at 100°C for 1.5 hours to obtain a high-transmittance LED diffuser plate.

[0062] The present invention also includes comparative examples and related experiments.

[0063] Comparative Example 1

[0064] Compared with Example 6, the only difference is that light-diffusing particles were not prepared, and cerium dioxide particles were used directly as light-scattering particles. The other preparation methods and components were completely consistent, and a high-transmittance LED diffuser plate was finally obtained.

[0065] Comparative Example 2

[0066] Compared with Example 6, the only difference is that the nanocellulose was not pretreated. The other preparation methods and components are completely the same, and a high-transmittance LED diffuser plate is finally obtained.

[0067] Comparative Example 3

[0068] Compared with Example 6, the only difference is that the mixed solution was not prepared as a coating. That is, 120 parts of polycarbonate, 0.5 parts of antioxidant 1098 and 3.2 parts of light diffusion particles were mixed and melt-blended using a twin-screw extruder at 265°C and 350 rpm, extruded, stretched, cooled and shaped, and cut to obtain a high-transmittance LED diffuser plate.

[0069] Performance testing

[0070] The high-transmittance LED diffuser plate samples prepared in Examples 1-6 and Comparative Examples 1-3 were tested for transmittance and haze according to GB / T2410-2008 Transparent Plastics Transmittance and Haze Determination, and the yellow index of the light diffuser plate was tested according to GB / T39822-2021 Plastic Yellow Index and its Variation Value Determination. If the yellow index of the sample was higher than 4, the sample was too yellow and did not meet the requirements. The examples and comparative examples were graded according to GB / T2408-2021 Plastic Combustion Performance Determination. The specific test results are shown in Table 1.

[0071] Table 1

[0072]

[0073] As shown in Table 1, the high-transmittance LED diffusers obtained in Examples 1-6 of this invention have a transmittance of >89.5% and a haze of >92%, which breaks through the contradiction between transmittance and haze of traditional diffusers.

[0074] Based on the analysis of the test data in Table 1, Comparative Example 1, due to the lack of modification of cerium dioxide particles, exhibited agglomeration, resulting in a significant decrease in light transmittance and haze, and a significant increase in the yellow index, failing to meet the standard requirements and significantly reducing flame retardant performance. Comparative Example 2, due to the lack of pretreatment of nanocellulose, had a coating that was inferior to that of Example 6, resulting in a decrease in haze and transparency. Furthermore, the poor density of the coating also had a certain impact on the yellow index. Comparative Example 3, due to the lack of preparation of a mixed solution as a coating, had a greater impact on the yellow index and also experienced a decrease in flame retardant performance.

[0075] Figure 1 The scattered light image was obtained by placing the samples in front of a laser lamp at a distance of approximately 20 cm, and then displaying the image against a dark background; Figure 1 (a) is a blank sample, i.e., a blank sample prepared without the addition of light-diffusing particles and without coating with a mixed solution. Figure (b) is a scattered light image of the sample of Example 6. The comparison shows that Example 6 has better light-diffusing ability.

[0076] In summary, the high-transmittance LED diffuser plate prepared by the method of this invention achieves good light diffusion while maintaining high transmittance and low haze.

[0077] The above are preferred embodiments of the present invention. Those skilled in the art can make several improvements and modifications without departing from the principle of the present invention, and these improvements and modifications should also be considered within the scope of protection of the present invention.

Claims

1. A manufacturing process for a high-transmittance LED diffuser plate, characterized in that, Includes the following steps: S1. Mix cerium nitrate hexahydrate and anhydrous ethanol, add triethanolamine and stir, centrifuge to remove the supernatant, add deionized water and methyl methacrylate while heating and stirring, raise the temperature, add potassium persulfate, vinyltrimethoxysilane and 3-mercaptopropyltrimethoxysilane, heat and stir, filter, wash, vacuum dry, add hydrogen peroxide solution, heat to react, centrifuge to collect the precipitate, disperse it in deionized water, add potassium hydroxide solution to adjust the pH to 12-13, reflux, adjust the pH to 7-8 with hydrochloric acid solution, centrifuge to collect the precipitate, and wash with methanol 2-3 times to finally obtain light-diffusing particles; S2. First, soak the nanocellulose in an aqueous solution of zinc chloride, then soak it in anhydrous ethanol, wash it, and dry it to obtain pretreated nanocellulose; add the pretreated nanocellulose to a cyclic olefin copolymer solution, and sonicate it to obtain a mixed solution. S3. After mixing polycarbonate and light diffusion particles, melt-blend them using a twin-screw extruder, extrude them, then draw them into strips, cool and shape them, and cut them to obtain an LED diffusion plate; drop the mixed solution onto the LED diffusion plate, spin-coat it, and dry it to obtain a high-transmittance LED diffusion plate.

2. The manufacturing process of a high-transmittance LED diffuser plate according to claim 1, characterized in that, In step S1, triethanolamine is added and stirred for 40-70 minutes. After centrifugation to remove the supernatant, the mixture is heated in a water bath at a rate of 5°C / min. Deionized water and methyl methacrylate are added under electromagnetic stirring. After the temperature rises to 70°C, potassium persulfate is added. Vinyltrimethoxysilane and 3-mercaptopropyltrimethoxysilane are slowly added dropwise over 30 minutes. The mixture is stirred and reacted at 70°C for 4 hours. After filtration, the mixture is washed 3-5 times with distilled water and then vacuum dried at 60°C for 12 hours.

3. The manufacturing process of a high-transmittance LED diffuser plate according to claim 1, characterized in that, The hydrogen peroxide solution has a volume concentration of 20%, the potassium hydroxide solution has a molar concentration of 1%, and the hydrochloric acid solution has a molar concentration of 1%.

4. The manufacturing process of a high-transmittance LED diffuser plate according to claim 1, characterized in that, The nanocellulose was prepared by dispersing hardwood pulp in deionized water, ball milling at 500 rpm for 80-120 min, vacuum filtering through a 0.22 μm filter membrane, and vacuum drying at 60 °C for 2 h.

5. The manufacturing process of a high-transmittance LED diffuser plate according to claim 1, characterized in that, The cyclic olefin copolymer solution was prepared by mixing and stirring toluene and cyclic olefin copolymer particles for 1 hour.

6. The manufacturing process of a high-transmittance LED diffuser plate according to claim 1, characterized in that, In step S2, the pretreated nanocellulose is obtained by immersing nanocellulose in a 25% zinc chloride aqueous solution at 75°C for 20-50 seconds, then immersing it in anhydrous ethanol for 10-20 minutes, washing it three times with flowing ethanol, and then drying it. The ultrasonic treatment is carried out in an ice bath for 300-500 minutes.

7. The manufacturing process of a high-transmittance LED diffuser plate according to claim 1, characterized in that, The LED diffuser plate is made by mixing polycarbonate, antioxidant 1098, and light diffusion particles, then melting and blending them using a twin-screw extruder at 200~265℃ and 300~350rpm, extruding, stretching, cooling and shaping, and cutting.

8. The manufacturing process of a high-transmittance LED diffuser plate according to claim 1, characterized in that, In step S3, the spin coating speed is 250 rpm and the time is 10-15 s, and the drying temperature is 80-100℃ and the time is 1-1.5 h.

9. The manufacturing process of a high-transmittance LED diffuser plate according to any one of claims 1 to 8, characterized in that, The high-transmittance LED diffuser plate comprises the following raw materials in parts by weight: 100-120 parts polycarbonate, 1.5-3.2 parts light-diffusing particles, and 2-5 parts mixed solution.

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