Large-size transparent optical plate with efficient Rayleigh scattering and brightness enhancement functions and preparation method of large-size transparent optical plate

Abstract

The invention discloses a high-efficiency Rayleigh scattering and brightness-enhanced large-size transparent optical plate and a preparation method thereof. The high-efficiency Rayleigh scattering and brightness-enhanced large-size transparent optical plate is a composite plate composed of the following three layers of structures: an upper brightness enhancement layer comprising base resin and a brightness enhancer; the middle Rayleigh scattering layer comprises base resin and a Rayleigh scattering agent; the lower hardening layer is formed by plating a layer of material which is high in hardness and not prone to embrittlement on the surface of the transparent optical plate through a soaking coating process. Through a specific material formula and process steps, efficient scattering of the large-size plate on blue light and remarkable improvement of the overall brightness are achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of optical materials, and particularly to a large-size transparent optical sheet with high-efficiency Rayleigh scattering and enhanced brightness and a preparation method thereof. Background Art

[0002] With the development of technology and the improvement of people's requirements for visual experience, transparent optical materials are increasingly widely used in various fields. The side-entry light blue sky panel is a lighting panel using side-entry light technology, which is used to simulate or enhance the indoor light effect, especially to simulate the blue sky effect. From the market performance of the blue sky lamp, since the blue sky lamp designed with the side-entry light blue sky panel has a thinner lamp thickness, is easy to install, has a beautiful shape, and the lighting product that simulates the blue sky effect is favored by consumers, especially in the occasions where the indoor light atmosphere needs to be improved.

[0003] However, the traditional side-entry light blue sky panels currently on the market generally have problems: either the blue saturation is insufficient or the brightness performance is poor. In particular, the Rayleigh scattering penetration distance of these blue sky panels is limited, usually not exceeding the size of 300 mm of the bidirectional side-entry light panel width, which results in the phenomenon of the panel surface turning yellow visually on the Rayleigh scattering panel, making it difficult to meet the market's pursuit of high-quality visual enjoyment. Especially when manufacturing large-size bidirectional side-entry light blue sky panels, the panel width size of the large-size bidirectional side-entry light blue sky panel is above 600 mm. Due to the large area of the sheet, the light is gradually weakened by the reflection of inorganic material particles during the penetration process, resulting in the loss of the Rayleigh scattering effect at a large distance and the inability to present the beautiful vision of Rayleigh scattering. For this reason, so far, no blue sky panel with a bidirectional side-entry light panel width reaching 600 mm has been launched on the market.

[0004] The application publication number CN 115903121 A, "Rayleigh Scattering Light Guide Plate and Its Manufacturing Method", discloses a Rayleigh scattering light guide plate. In terms of the manufacturing process of the Rayleigh scattering light guide plate, the manufacturing method of the Rayleigh scattering light guide plate adopts the casting method, including: pre-polymerizing the MMA resin material; adding nano-TiO2 particles and light guide powder, making a slurry, and performing defoaming treatment; grouting according to the prepared template, and then performing water bath polymerization; after entering the baking room for polymerization treatment, demolding and cutting.

[0005] The Rayleigh scattering light guide plate includes a transparent substrate and nano-TiO2 particles and light guide powder are uniformly dispersed inside the transparent substrate, as Figure 1 shown in the figure: transparent substrate 11, light guide powder 122, nano-TiO2 particles 121. Its invention provides a Rayleigh scattering light guide plate, which not only has a light guiding function but also has a Rayleigh scattering phenomenon, and can directly replace the light guide plate and diffusion plate in the traditional side-emitting flat lamp.

[0006] In terms of the manufacturing process of the Rayleigh scattering light guide plate, the casting method is adopted. This method has a complex process and low production efficiency. Regarding the structure of a Rayleigh scattering light guide plate provided by the invention, it is characterized in that nano-TiO2 particles and light guide powder particles are simultaneously incorporated into the transparent substrate. The addition of the light guide powder aims to optimize the diffusion performance of the diffuse reflection light source and ensure that the light can be more evenly distributed inside the transparent substrate. However, this improvement measure also brings a side effect: the haze of the transparent sheet increases. This is because the light guide powder particles themselves act as scattering centers, causing the light to scatter when passing through the material, thereby increasing the haze level.

[0007] The increase in haze will undoubtedly reduce the clarity of the transparent material, making the line of sight blurred when passing through the material. This phenomenon has an adverse effect on the Rayleigh scattering effect because the increase in haze will disrupt the propagation trajectory and intensity distribution of the light, thereby weakening the visual effect of Rayleigh scattering. Especially at a relatively far distance, the Rayleigh scattering phenomenon is weakened due to the interference of the light guide powder particles. The Rayleigh scattering penetration distance of the blue sky plate is limited, and yellowing often occurs, thus affecting the overall visual experience of Rayleigh scattering.

[0008] Grant publication number: CN 217360363 U. Utility model name: A multi-layer composite nano-scattering plate, (simultaneously applied invention patent: Application publication number: CN 112649908 A. Invention name: Multi-layer composite nano-scattering plate and its preparation method). This scattering plate includes a light incident layer (1) for receiving light and a light exit layer (2) for emitting light; The light incident layer (1) includes a transparent medium and first nano-particles (A) dispersed in the transparent medium for forming Rayleigh scattering; the light incident layer (1) is a single-layer structure of 1-5 layers; The light exit layer (2) includes a transparent medium and second nano-particles (B) dispersed in the transparent medium for light diffusion, or uses a texture, frosted structure, etc. to play a role in light diffusion, achieving a certain light transmittance and haze; The preparation method of the invented multi-layer composite nano-scattering plate, the multi-layer structure is prepared by a multi-layer co-extrusion composite, hot pressing, coating or casting molding process. The specific method is as follows: (1) Add 60-70% nano-particles to an organic solvent, and disperse them by ultrasonic waves to obtain a nano-particle mixture; among them, the organic solvent is xylene; (2) Add 1%-2% white oil to the transparent resin substrate, and mix evenly using a magnetic heating stirrer. After the resin surface is wetted, add the above nano-particle mixture so that the mass ratio of the nano-particles accounts for 0.01‰-5% of the mass of the resin substrate. Continue to mix evenly using a stirrer and heat at a low temperature. The heating temperature is 30-50°C to volatilize the solvent and obtain a uniform mixture of resin and nano-particles; (3) Using 1 to 5 extruders to supply resin or a mixture of resin and nanoparticles respectively according to the number of layers of the sheet, and merging them in a composite die to obtain a multilayer sheet, wherein the extrusion processing temperature is 180-250°C.

[0009] In terms of the preparation process of the multilayer composite nano-scattering plate, the organic solvent xylene is used to disperse the nanoparticles of the particle material, and the nanoparticle mixture is obtained by ultrasonic dispersion. The mixture is then heated and stirred with the resin to obtain a uniform mixture of the resin and the nanoparticles.

[0010] Firstly, in the application specification of patent CN 217360363 U, regarding this nano-dispersion technology, the specific method of dispersing particles to nano-particle size by ultrasonic means and the corresponding characterization are not mentioned.

[0011] Secondly, the toxicity of xylene and its impact on human health and the environment are well known. Xylene is recognized by the World Health Organization as a Class 2 carcinogen, and long-term exposure to xylene may increase the risk of malignant tumors, such as lymphoma. Xylene waste gas leaks through the soil surface or underground pipelines, which will pollute the soil and affect the growth and quality of crops.

[0012] From the structure of a multi-layer composite nano-scattering plate provided by the invention, the scattering plate consists of two parts: a light-entering layer, which is composed of a transparent medium and nanoparticles dispersed therein; and a light-emitting layer, which is also composed of a transparent medium, but in which particles with a particle size between 500nm and 100μm are dispersed to achieve a light diffusion effect. Analyzing the impact of this structure on optical performance, it can be found that the particles within these particle size ranges introduced into the light-emitting layer, coupled with the light-emitting layer being designed at the lower part of the multi-layer composite nano-scattering plate, are intended to enhance the diffusion performance of the diffusely reflected light source and promote a more uniform distribution of light inside the transparent substrate.

[0013] However, these relatively coarse particles not only act as scattering centers, but also inevitably increase the haze of the transparent sheet. This causes the light to scatter when passing through the light-emitting layer, which in turn reduces the transmittance of the light, weakens the clarity of the transparent material, and makes the line of sight blurry when penetrating the material, and may cause whitening, which directly affects the visual effect of Rayleigh scattering. In addition, the increase in haze also disrupts the propagation path and intensity distribution of light, resulting in a weakening of the Rayleigh scattering effect at a distance from the light source, which in turn affects the Rayleigh scattering penetration distance of the blue sky board. This change causes the blue sky board to appear yellowish at a closer position, destroying the Rayleigh scattering characteristics on which the overall blue light visual effect depends.

[0014] The multi-layer composite nano-scattering plate adopts a differential functional layer design. Its light-incident layer is composed of a transparent matrix and dispersed nano-particles, achieving efficient coupling and primary regulation of incident light through the nano-scale scattering effect. The light-emitting layer is located at the bottom of the structure, with a transparent medium loaded with particles in the range of 500 nm - 100 μm. The multiple light diffusion effects of the micron-scale scatterers are used to optimize the distribution of the emitted light field. However, while the micron-scale particles introduced in the light-emitting layer enhance the light uniformity, they significantly increase the haze value of the system, resulting in disordered light transmission paths and decreased transmittance. The micron particles, as strong scattering centers, trigger high-frequency scattering events, which not only deteriorate the transparency of the material (manifested as visual blurring and surface whitening), but also obscure the Rayleigh scattering effect dominated by the nano-structure in the light-incident layer. Since Rayleigh scattering depends on the matching of the scatterer size and the light wavelength, the Mie scattering of micron-scale particles will destroy the selective scattering characteristics of short wavelengths (blue light), making it difficult for the material to present a pure Rayleigh scattering visual effect. Further, the non-selective scattering of micron particles causes an abnormal spatial attenuation gradient in the blue light transmission. Its short-wavelength component preferentially attenuates during penetration due to a larger scattering cross-section, resulting in a shortened effective propagation distance of Rayleigh scattering. At the same time, the proportion of the remaining red and yellow light increases relatively with the increase of the transmission distance, showing a yellowing phenomenon at the far end of the cyan sky plate during off-axis observation. This color temperature shift effect significantly deviates from the spectral characteristics of the natural sky blue region simulated by Rayleigh scattering. In summary, although this hierarchical scattering structure expands the light regulation dimension through size gradient design, the optical side effects of the micron-scale light-emitting layer highlight the inherent contradiction between function enhancement and optical quality. It is necessary to achieve a coordinated improvement of scattering efficiency and visual fidelity through strategies such as optimizing the particle size distribution and tuning the interface refractive index.

[0015] Therefore, in order to correct the above-mentioned defects, we propose a large-size transparent optical sheet with high-efficiency Rayleigh scattering and brightness enhancement and a preparation method thereof. Summary of the Invention

[0016] The technical problem solved by the present invention is to provide a large-size transparent optical sheet with high-efficiency Rayleigh scattering and brightness enhancement and a preparation method thereof. The large-size transparent optical sheet with high-efficiency Rayleigh scattering and brightness enhancement is composed of an upper brightening layer, a middle Rayleigh scattering layer, and a lower hardening layer. The upper and lower layers enhance the brightening effect without losing the Rayleigh scattering function of the Rayleigh scattering layer. Since all three layers are highly transparent, the composed transparent optical sheet will not produce haze effects, thus reflecting a clear Rayleigh scattering vision on the large-size transparent optical sheet and achieving the dual effects of high-efficiency Rayleigh scattering and brightness enhancement.

[0017] To achieve the above object, the present invention provides the following technical solution: A large-size transparent optical sheet with high-efficiency Rayleigh scattering and brightness enhancement, which is a composite sheet composed of the following three-layer structure: Upper brightening layer: Comprising a base resin and a brightness enhancer; Intermediate Rayleigh scattering layer: comprising a base resin and a Rayleigh scattering agent; Lower hardening layer: A material with high hardness and not easily brittle is coated on the surface of the transparent optical sheet by an immersion coating process; The sheet is in a light two-way side-in mode, with a Rayleigh scattering penetration distance ≥ 600 mm, a haze value ≤ 2%, and a light transmittance ≥ 88%; The Rayleigh scattering agent is an aqueous nanoparticle dispersion liquid in which specially treated inorganic material nanoparticles with a high refractive index are uniformly dispersed in water. During the preparation of the large-size transparent optical sheet, these nanoparticles are effectively dispersed and incorporated into the base resin matrix to form a stable Rayleigh scattering effect; The brightness enhancer is an aqueous nanoparticle dispersion liquid in which inorganic material transparent nanoparticles with refractive and reflective functions are uniformly dispersed in water. During the preparation of the large-size transparent optical sheet, these nanoparticles are effectively dispersed and incorporated into the base resin matrix; The hardening layer is coated with a scratch-resistant, wear-resistant, and antistatic coating on the surface of the transparent optical sheet through an immersion coating process, and a scratch-resistant, wear-resistant, and antistatic coating is coated on the surface of the transparent optical sheet, while improving the overall brightness of the sheet.

[0018] Further, the base resin is selected from transparent resins with high light transmittance, low light absorption, and good processing performance, including polymethyl methacrylate (PMMA), polycarbonate (PC), polystyrene (PS), or their copolymers; polyethylene terephthalate (PET), cycloolefin copolymer (COC / COP), transparent modified PP, polyethersulfone (PES) & polysulfone (PSU), polyethylene naphthalate (PEN), transparent thermoplastic polyurethane (TPU), etc.; one or more of them; The inorganic material nanoparticles with a high refractive index include: one or more of zinc selenide, zinc sulfide, chromium oxide, bismuth vanadate, titanium dioxide, and inorganic materials such as silica (low refractive index material); The inorganic material transparent nanoparticles include one or more of silica, fused quartz, and graphene.

[0019] Another object of the present invention is provided: A method for preparing a large-size transparent optical sheet with high-efficiency Rayleigh scattering and brightness enhancement, comprising the following steps: S1. Prepare the Rayleigh scattering agent: Mix 10 - 15 parts of inorganic material particles with a high refractive index, 100 parts of deionized water, and 3 - 10 parts of an aqueous inorganic material particle dispersant, and grind them with a nano sand mill to obtain an aqueous nanoparticle dispersion liquid with a nanoparticle particle size distribution range D90 of 50 nm - 110 nm; S2. Preparation of brightness enhancer: Mix 15 - 25 parts of inorganic material transparent particles, 100 parts of deionized water, and 6 - 15 parts of inorganic material transparent particle aqueous dispersant, and grind them with a nano sand mill to obtain an inorganic material transparent particle aqueous nano - dispersion with a nano - particle size distribution range D90 of 60 nm - 110 nm; S3. Preparation of masterbatch of high - efficiency Rayleigh scattering layer material: Take 100 parts of the base resin and 0.1 - 0.5 parts of the aqueous nano - particle dispersion of inorganic material (Rayleigh scattering agent). First, add 100 parts of the base resin to a stirring tank, and then spray the aqueous nano - particle dispersion of inorganic material (Rayleigh scattering agent) into the stirring tank with an ultrasonic spraying device (commercially available) and stir evenly. During the stirring process, heat the temperature to 60 - 100 °C, mix for 1 - 2 hours, and then add it to a differential co - rotating twin - screw extruder for extrusion granulation to obtain the masterbatch of high - efficiency Rayleigh scattering layer material; S4. Preparation of masterbatch of brightening layer material: Take 100 parts of the base resin and 3 - 8 parts of the aqueous nano - particle dispersion of inorganic material transparent particles (brightness enhancer). First, add 100 parts of the base resin to a stirring tank, and then spray the aqueous nano - dispersion of inorganic material transparent particles (brightness enhancer) into the stirring tank with an ultrasonic spraying device (commercially available) and stir evenly. During the stirring process, heat the temperature to 60 - 100 °C, mix for 1 - 2 hours, and then add it to a differential co - rotating twin - screw extruder for extrusion granulation to obtain the masterbatch of brightening layer material; S5. Co - extrusion compound molding: Mix the masterbatch of high - efficiency Rayleigh scattering layer material with the base resin according to the mass ratio of high - refractive - index inorganic material nano - particles in the high - efficiency Rayleigh scattering layer ranging from one in ten million to one in one hundred thousand parts to obtain the high - efficiency Rayleigh scattering layer material. Mix the masterbatch of brightening layer material with the base resin according to the mass ratio of inorganic material transparent nano - particles in the brightening layer ranging from one in one million to one in ten thousand. Then, use the co - extrusion compounding method to co - extrude and compound (the high - efficiency Rayleigh scattering layer material and the brightening layer material) at a mass ratio of 90 - 95:10 - 5 parts to obtain a large - size transparent optical composite sheet with high - efficiency Rayleigh scattering and brightness enhancement; S6. Post - treatment of hard coat layer: Perform immersion coating treatment on the formed sheet to enhance its surface hardness and anti - static property, keep the board surface clean and dust - proof, and further improve the brightness.

[0020] Further, the inorganic material particle aqueous dispersant is one or more of polycarboxylate dispersants, anionic phosphate ester dispersants, and silane - coupling - agent - modified dispersants; The inorganic material transparent particle aqueous dispersant is one or more of polycarboxylate dispersants, phosphate dispersants, and non - ionic surfactants.

[0021] Further, the preparation method of the hard coat layer includes the following steps: S5.1. Preparation of the hardening layer nanoparticle material dispersion: Mix 5 - 10 parts of silica material particles, 100 parts of isopropyl alcohol, 3 - 10 parts of an oily dispersant, and 1 - 5 parts of a transparent antistatic agent, and add them to a nano - sand mill for grinding for 3 - 6 hours to obtain a hardening layer nanoparticle material dispersion with a nanoparticle size distribution range D90 of 60 nm - 100 nm; S5.2. Preparation of the hardening layer immersion - coating nanoparticle solution: Formula of the immersion - coating nanoparticle solution: 100 parts of organosilicon resin - polyalkylaryl organosilicon resin, 0.2 - 2 parts of the hardening layer nanoparticle material dispersion, 2 - 5 parts of a surfactant, 2 - 5 parts of a cross - linker (silane coupling agent), 0.1 - 1 part of a catalyst (acid / base), an appropriate amount of solvent, etc.; S5.3. Preparation: a. Add the organosilicon resin to the solvent and stir evenly; add the nanoparticle dispersion, and use ultrasonic dispersion or mechanical stirring to ensure that the nanoparticles are evenly dispersed; add the surfactant and continue stirring; add the cross - linker and the catalyst and stir evenly to form a stable coating solution; b. Immersion coating Immerse the pretreated substrate into the prepared coating solution. The immersion time is adjusted according to the substrate material and the coating thickness requirements, usually 1 - 10 minutes; the substrate can be gently shaken during the immersion process to ensure that the solution evenly covers the surface.

[0022] c. Pull - up film formation Slowly pull the substrate out of the solution at a constant speed to form a uniform liquid film; d. Pre - drying: Pre - dry the coated substrate at room temperature or low temperature (such as 50 - 80 °C) to volatilize the solvent and form a preliminary coating; e. Curing treatment Put the pre - dried substrate into an oven and cure it at an appropriate temperature (such as 60 - 80 °C) for 30 - 60 minutes to allow the organosilicon resin to fully react with the cross - linker and form a dense coating.

[0023] Furthermore, in step S5.1, The oily dispersant: includes polyurethane - type dispersants and acrylic - type dispersants; The transparent antistatic agent: includes polymer antistatic agents, chemical name: polyethers, specific model: such as PEG-400 (polyethylene glycol 400); inorganic salt antistatic agents, chemical name: metal oxides, specific model: such as ATO (antimony-doped tin oxide); silicone antistatic agents, chemical name: siloxanes, specific model: such as BYK-ES80 (polyether-modified silicone); carbon-based antistatic agents, chemical name: carbon nanotubes, graphene, specific model: such as NC7000 (carbon nanotubes); composite antistatic agents, chemical name: multiple components composite, specific model: such as Irgastat P18 (multiple antistatic agents composite); nano antistatic agents, chemical name: nano metal oxides, specific model: such as Nanobyk-3600 (nano zinc oxide).

[0024] Further, in the step S5.2, The catalyst (acid / base): includes p-toluenesulfonic acid (p-TSA), hydrochloric acid (HCl), ammonia water (NH4OH), sodium hydroxide (NaOH), or potassium hydroxide (KOH); The surfactant: includes non-ionic surfactants, anionic surfactants, and cationic surfactants.

[0025] Compared with the prior art, the beneficial effects of the present invention are: through specific material formulations and process steps, the present invention realizes the efficient scattering of blue light by large-size plates and a significant improvement in the overall brightness: A large-size transparent optical plate with high-efficiency Rayleigh scattering and brightness enhancement, which is composed of an upper brightening layer, a middle Rayleigh scattering layer, and a lower hardening layer. The upper and lower layers enhance the brightening effect without losing the Rayleigh scattering function of the Rayleigh scattering layer. Since all three layers are highly transparent, the composed transparent optical plate will not produce haze effects, thus reflecting a clear Rayleigh scattering vision on the large-size transparent optical plate and achieving the dual effects of high-efficiency Rayleigh scattering and brightness enhancement; The large-sized transparent optical sheet with three-layer high-efficiency Rayleigh scattering and brightness enhancement is organically combined. The Rayleigh scattering layer has the function of Rayleigh scattering, producing a stable Rayleigh scattering effect; the brightness enhancement layer contains inorganic nano-material transparent particles, with two functions. One is to refract and reflect light, increasing the light transmission on the board surface and enhancing the projection brightness of the light out of the board surface; the other is that the nano-material particles in the brightness enhancement layer are transparent particles. After passing through the Rayleigh scattering layer visually, there is no hazy visual feeling, giving a deep blue sky feeling; the hardening layer not only enhances the scratch resistance, crack resistance and antistatic property of the sheet, but also contains transparent silica nano-particles. These transparent particles also contribute to the efficient light transmission on the sheet surface, further improving the brightness of the emitted light, also playing a role in increasing the light transmission on the board surface, ensuring the dual improvement of the durability of the overall structure and the optical performance, enhancing the projection brightness of the light out of the board surface, and at the same time ensuring the dust-proof and smoothness of the board surface. Description of the Drawings

[0026] Figure 1 It is the particle size measurement diagram of the aqueous nano-particle dispersion liquid of the Rayleigh scattering agent in Example 1; Figure 2 It is the particle size measurement diagram of the aqueous nano-particle dispersion liquid of the brightness enhancer; Figure 3 It is the electron microscope scanning diagram of the transparent optical composite sheet in Example 1; Figure 4 It is the particle size measurement diagram of the silica nano-dispersion liquid; Figure 5 It is the particle size measurement diagram of the aqueous zinc selenide nano-particle dispersion liquid in Example 2; Figure 6 It is the particle size measurement diagram of the aqueous nano-dispersion liquid of the fused quartz transparent particles; Figure 7 It is the electron microscope scanning diagram of the transparent optical composite sheet in Example 2; Figure 8 It is the particle size measurement diagram of the silica nano-dispersion liquid in the hardening layer; Figure 9 It is the particle size measurement diagram of the aqueous bismuth vanadate nano-particle dispersion liquid; Figure 10 It is the particle size measurement diagram of the aqueous nano-dispersion liquid of the graphene transparent particles; Figure 11 It is the electron microscope scanning diagram of the transparent optical composite sheet in Example 3; Figure 12 It is the particle size measurement diagram of the silica nano-dispersion liquid in the hardening layer; Figure 13 It is the particle size measurement diagram of the aqueous nano-dispersion liquid of the titanium dioxide material particles; Figure 14 It is the electron microscope scanning diagram of the Rayleigh scattering optical transparent sheet in Comparative Example 1; Figure 15 Particle size measurement diagram of the aqueous nano-dispersion of the titanium dioxide material particles of Comparative Example 2; Figure 16 SEM image of the Rayleigh scattering optically transparent sheet of Comparative Example 2; Figure 17 Particle size measurement diagram of the aqueous nano-dispersion of the titanium dioxide material particles of Comparative Example 2; Figure 18 SEM image of the Rayleigh scattering optically transparent sheet of Comparative Example 3; Figure 19 Diagram showing the Rayleigh scattering penetration distance measured in the examples and comparative examples. Detailed implementation manners

[0027] Next, the technical solutions in the embodiments of the present invention will be clearly and completely described in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, rather than all the embodiments. All other embodiments obtained by those of ordinary skill in the art based on the embodiments of the present invention without creative efforts shall fall within the protection scope of the present invention.

[0028] The present invention provides a technical solution: a large-size transparent optical sheet with high-efficiency Rayleigh scattering and brightness enhancement and a preparation method thereof, specifically as follows: Examples

[0029] As Figures 1 - 4 shown, the preparation of the large-size transparent optical sheet with high-efficiency Rayleigh scattering and brightness enhancement includes the following steps: Prepare a Rayleigh scattering agent: Mix 10 parts of titanium dioxide, 100 parts of deionized water, and 3 parts of a polycarboxylate dispersant, and grind them with a nano sand mill to obtain an aqueous nano-dispersion of titanium dioxide particles with a D90 value of the nano-particle size distribution range of 85 nm; Prepare a brightness enhancer: Mix 15 parts of silica, 100 parts of deionized water, and 6 parts of a polycarboxylate dispersant, and grind them with a nano sand mill to obtain an aqueous nano-dispersion of inorganic material transparent particles of silica with a D90 value of the nano-particle size distribution range of 80 nm; Prepare a masterbatch of the high-efficiency Rayleigh scattering layer material: Take 100 parts of PMMA and 0.1 part of the aqueous nano-dispersion of titanium dioxide particles. First, add 100 parts of the base resin to the stirring tank, and then spray the aqueous nano-dispersion of titanium dioxide particles into the stirring tank with an ultrasonic spraying device (commercially available) and stir evenly; during the stirring process, heat the temperature to 60 °C, mix for 1 hour, and add it to a differential co-rotating twin-screw extruder to extrude and pelletize to obtain a masterbatch of the high-efficiency Rayleigh scattering layer material; Preparation of the masterbatch for the brightening layer material: Take 100 parts of the PMMA and 3 parts of the aqueous silica nanoparticle dispersion. First, add 100 parts of the base resin to the stirring tank, and then spray the aqueous nanoparticle dispersion of the inorganic material transparent particles of the inorganic material into the stirring tank using an ultrasonic spray device (commercially available) and stir evenly. During the stirring process, heat the temperature to 60 °C, mix for 1 hour, and then add it to a differential co-rotating twin-screw extruder to extrude and pelletize to obtain the masterbatch for the brightening layer material; Co-extrusion composite molding: Mix the masterbatch of the Rayleigh scattering layer material and the PMMA resin in a mass ratio of 1:1000, and mix the masterbatch of the brightening layer material and the PMMA resin in a mass ratio of 1:100. Adopt the co-extrusion composite method to co-extrusion and mold the high-efficiency Rayleigh scattering layer mixture and the brightening layer mixture in a mass ratio of 90:10 to obtain a large-size transparent optical composite sheet with high-efficiency Rayleigh scattering and enhanced brightness; Post-treatment of the hardening layer: Soak and coat the molded sheet to enhance its surface hardness and anti-static property, keep the board surface clean and dust-proof, and further improve the brightness; The preparation method of the hardening layer includes the following steps: Preparation of the hardening layer nanoparticle material dispersion: Mix 5 parts of silica material particles, 100 parts of isopropyl alcohol, 3 parts of polyurethane dispersant, and 1 part of inorganic salt antistatic agent, and grind them in a nano sand mill for 3 hours to obtain a hardening layer nanoparticle material dispersion with a D90 value of the nanoparticle particle size distribution range of 90 nm; Preparation of the hardening layer immersion coating nanoparticle solution: Formula of the immersion coating nanoparticle solution: 100 parts of organosilicon resin - polyalkylaryl organosilicon resin, 0.2 parts of the hardening layer nanoparticle material dispersion, 2 parts of non-ionic surfactant, 2 parts of cross-linking agent (silane coupling agent), 0.1 part of p-toluenesulfonic acid, appropriate amount of solvent, etc.

[0030] Formulation process method: a. Add the organosilicon resin to the solvent and stir evenly. Add the nanoparticle dispersion, and use ultrasonic dispersion or mechanical stirring to ensure that the nanoparticles are evenly dispersed. Add the surfactant and continue stirring. Add the cross-linking agent and catalyst and stir evenly to form a stable coating solution.

[0031] b. Immersion coating Immerse the pretreated substrate into the prepared coating solution, and adjust the immersion time according to the substrate material and the coating thickness requirements, usually 1 minute. The substrate can be gently shaken during the immersion process to ensure that the solution evenly covers the surface.

[0032] c. Dipping to form a film Slowly lift the substrate out of the solution at a constant speed to form a uniform liquid film.

[0033] d. Pre-drying: The coated substrate is pre-dried at 50 °C to volatilize the solvent and form a preliminary coating.

[0034] e. Curing treatment The pre-dried substrate is placed in an oven and cured at a proper temperature of 60 °C for 30 minutes to allow the silicone resin to react fully with the cross-linking agent and form a dense coating.

[0035] Example 2 As Figures 5 - 8 shown, the preparation of a large-size transparent optical sheet with high-efficiency Rayleigh scattering and brightness enhancement includes the following steps: Preparation of Rayleigh scattering agent: 12 parts of zinc selenide material particles, 100 parts of deionized water, and 6 parts of anionic phosphate dispersant are mixed and ground by a nano sand mill to obtain a zinc selenide aqueous nano-particle dispersion with a D90 of 100 nm for the nano-particle size distribution range. Preparation of brightness enhancer: 20 parts of fused quartz particles, 100 parts of deionized water, and 10 parts of phosphate dispersant are mixed and ground by a nano sand mill to obtain a fused quartz transparent particle aqueous nano-dispersion with a D90 of 102 nm for the nano-particle size distribution range. Preparation of masterbatch for high-efficiency Rayleigh scattering layer material: Take 100 parts of the PS resin and 0.3 parts of the zinc selenide aqueous nano-particle dispersion. First, add 100 parts of the PS resin to a stirring tank, and then spray the aqueous zinc selenide nano-particle dispersion into the stirring tank using an ultrasonic spray device (commercially available) and stir evenly. During the stirring process, heat to a temperature of 80 °C, mix for 1.5 hours, and then add to a differential co-rotating twin-screw extruder to extrude and pelletize to obtain a masterbatch for high-efficiency Rayleigh scattering layer material. Preparation of masterbatch for brightening layer material: Take 100 parts of the PS resin and 6 parts of the fused quartz transparent particle aqueous nano-dispersion. First, add 100 parts of the PS resin to a stirring tank, and then spray the fused quartz transparent particle aqueous nano-dispersion into the stirring tank using an ultrasonic spray device (commercially available) and stir evenly. During the stirring process, heat to a temperature of 100 °C, mix for 1.5 hours, and then add to a differential co-rotating twin-screw extruder to extrude and pelletize to obtain a masterbatch for brightening layer material. Co-extrusion composite molding: Mix the masterbatch for Rayleigh scattering layer material and the PS resin in a mass ratio of 1:100, and mix the masterbatch for brightening layer material and the PS resin in a mass ratio of 1:10. Use the co-extrusion composite method to co-extrusion and composite the high-efficiency Rayleigh scattering layer mixture and the brightening layer mixture in a mass ratio of 92:8 to obtain a large-size transparent optical composite sheet with high-efficiency Rayleigh scattering and brightness enhancement. Post-treatment of hard coating layer: The formed sheet is subjected to immersion coating treatment to enhance its surface hardness and anti-static property, keep the surface of the sheet clean and dust-free, and further improve the brightness.

[0036] Method for preparing a hardening layer, comprising the following steps: Preparation of a hardening layer nanoparticle material dispersion: Mix 8 parts of silica material particles, 100 parts of isopropanol, 6 parts of an acrylic dispersant, and 3 parts of an organosilicon antistatic agent, and grind in a nano sand mill for 4.5 hours to obtain a hardening layer nanoparticle material dispersion with a nanoparticle particle size distribution range D90 of 105 nm; Preparation of a soaking coating nanoparticle solution for the hardening layer: Formula of the soaking coating nanoparticle solution: 100 parts of an organosilicon resin - polyalkylaryl organosilicon resin, 1.0 part of a hardening layer silica nano dispersion, 3 parts of an anionic surfactant, 3 parts of a crosslinking agent (silane coupling agent), 0.5 part of ammonia water, an appropriate amount of solvent, etc.

[0037] Formulation process method: a. Add the organosilicon resin to the solvent and stir evenly. Add the nanoparticle dispersion, and use ultrasonic dispersion or mechanical stirring to ensure uniform dispersion of the nanoparticles. Add the surfactant and continue stirring. Add the crosslinking agent and catalyst, and stir evenly to form a stable coating solution.

[0038] b. Soaking coating Immerse the pretreated substrate in the prepared coating solution, and adjust the soaking time according to the substrate material and coating thickness requirements, usually 5 minutes. The substrate can be gently shaken during the soaking process to ensure uniform coverage of the surface by the solution.

[0039] c. Pulling to form a film Slowly pull the substrate out of the solution at a constant speed to form a uniform liquid film.

[0040] d. Pre - drying: Pre - dry the coated substrate at 60 °C to volatilize the solvent and form a preliminary coating.

[0041] e. Curing treatment Put the pre - dried substrate into an oven and cure it at an appropriate temperature of 70 °C for 40 minutes to allow the organosilicon resin to fully react with the crosslinking agent and form a dense coating.

[0042] Example 3 As Figures 9 - 12 shown, the preparation of a large - size transparent optical sheet with high - efficiency Rayleigh scattering and brightness enhancement comprises the following steps: Preparation of a Rayleigh scattering agent: Mix 15 parts of bismuth vanadate particles, 100 parts of deionized water, and 10 parts of a silane coupling agent - modified dispersant, and grind in a nano sand mill to obtain a bismuth vanadate aqueous nanoparticle dispersion with a nanoparticle particle size distribution range D90 of 110 nm; Preparation of brightness enhancer: Mix 25 parts of graphene transparent particles, 100 parts of deionized water, and 15 parts of non-ionic surfactant, and grind them with a nano sand mill to obtain an aqueous nano-dispersion of graphene transparent particles with a D90 value of the nano-particle size distribution range of 109 nm; Preparation of high-efficiency Rayleigh scattering layer material masterbatch: Take 100 parts of the PC resin and 0.5 part of the aqueous nano-dispersion of bismuth vanadate nanoparticles. First, add 100 parts of the PC resin to a stirring tank, and then spray the aqueous nano-dispersion of bismuth vanadate nanoparticles into the stirring tank with an ultrasonic spraying device (commercially available) and stir evenly; during the stirring process, heat the temperature to 100 °C, mix for 2 hours, and add it to a differential co-rotating twin-screw extruder to extrude and pelletize to obtain a high-efficiency Rayleigh scattering layer material masterbatch; Preparation of brightening layer material masterbatch: Take 100 parts of the PC resin and 8 parts of the aqueous nano-dispersion of graphene transparent particles. First, add 100 parts of the PC resin to a stirring tank, and then spray the aqueous nano-dispersion of graphene transparent particles into the stirring tank with an ultrasonic spraying device (commercially available) and stir evenly; during the stirring process, heat the temperature to 100 °C, mix for 2 hours, and add it to a differential co-rotating twin-screw extruder to extrude and pelletize to obtain a brightening layer material masterbatch; Co-extrusion composite molding: Mix the mass ratio of the Rayleigh scattering layer material masterbatch to the PC resin at 1:10, and the mass ratio of the brightening layer material masterbatch to the PC resin at 1:1. Adopt the co-extrusion composite method to co-extrusion and mold the high-efficiency Rayleigh scattering layer mixture and the brightening layer mixture according to the mass ratio of 95:5 to obtain a large-size transparent optical composite sheet with high-efficiency Rayleigh scattering and brightness enhancement; Post-treatment of the hardening layer: Perform immersion coating treatment on the formed sheet to enhance its surface hardness and anti-static property, keep the plate surface clean and dust-free, and further improve the brightness.

[0043] The preparation method of the hardening layer includes the following steps: Preparation of the hardening layer nano-particle material dispersion: Mix 10 parts of silica material particles, 100 parts of isopropanol, 10 parts of polyurethane dispersant, and 5 parts of a composite anti-static agent, and grind them with a nano sand mill for 6 hours to obtain a hardening layer nano-particle material dispersion with a D90 value of the nano-particle size distribution range of 96 nm; Preparation of the hardening layer immersion coating nano-particle solution: Formula of the immersion coating nano-particle solution: 100 parts of organosilicon resin - polyalkylaryl organosilicon resin, 2 parts of the hardening layer silica nano-particle material dispersion, 5 parts of sodium hydroxide, 5 parts of cross-linking agent (silane coupling agent), 1 part of sodium hydroxide, and an appropriate amount of solvent, etc.

[0044] Formulation process method: a. Add silicone resin into a solvent and stir evenly. Add the nanoparticle dispersion and use ultrasonic dispersion or mechanical stirring to ensure the uniform dispersion of the nanoparticles. Add a surfactant and continue stirring. Add a crosslinking agent and a catalyst, stir evenly to form a stable coating solution.

[0045] b. Immersion coating Immerse the pretreated substrate into the prepared coating solution. Adjust the immersion time according to the substrate material and the coating thickness requirement, usually 10 minutes. The substrate can be gently shaken during the immersion process to ensure the solution evenly covers the surface.

[0046] c. Drawing into film Slowly draw the substrate out of the solution at a constant speed to form a uniform liquid film.

[0047] d. Pre-drying Pre-dry the coated substrate at 80 °C to volatilize the solvent and form a preliminary coating.

[0048] e. Curing treatment Put the pre-dried substrate into an oven and cure it at an appropriate temperature of 80 °C for 60 minutes to make the silicone resin fully react with the crosslinking agent and form a dense coating.

[0049] Comparative Example 1 As Figures 13 - 14 shown, a method for preparing a Rayleigh scattering transparent optical sheet includes the following steps (without a brightening layer): Preparing a Rayleigh scattering agent: Mix 10 parts of high titanium dioxide material particles, 100 parts of deionized water, and 3 parts of a polycarboxylate dispersant, and grind them with a nano sand mill to obtain an aqueous titanium dioxide nanoparticle dispersion with a nanoparticle size distribution range D90 of 83 nm; Preparing a Rayleigh scattering material masterbatch: Take 100 parts of the PMMA resin and 0.1 part of the aqueous titanium dioxide nanoparticle dispersion of the inorganic material. First, add 100 parts of the PMMA resin to a stirring tank, and then spray the aqueous titanium dioxide nanoparticle dispersion into the stirring tank with an ultrasonic spraying device (commercially available) and stir evenly; during the stirring process, heat the temperature to 60 °C, mix for 1 hour, and add it to a differential co-rotating twin-screw extruder to extrude and pelletize to obtain a high-efficiency Rayleigh scattering material masterbatch; Extrusion molding: Mix the Rayleigh scattering material masterbatch and the PMMA resin in a ratio of 1:1000 to obtain a Rayleigh scattering mixture, and use an extrusion press to extrude and mold to obtain a Rayleigh scattering transparent optical sheet.

[0050] Comparative Example 2 As Figures 15 - 16 shown, a method for preparing a Rayleigh scattering transparent optical sheet includes the following steps: Preparation of Rayleigh scattering agent: Mix 10 parts of titanium dioxide particles, 100 parts of deionized water and 3 parts of silane coupling agent modified dispersant, and grind them with a nano sand mill to obtain a water-based nano titanium dioxide particle dispersion liquid with a D90 value of the nano particle size distribution range of 110 nm; Preparation of Rayleigh scattering material masterbatch: Take 100 parts of the PMMA resin and 0.1 part of the water-based nano titanium dioxide particle dispersion liquid. First, add 100 parts of the PMMA resin to a stirring tank, and then spray the water-based nano titanium dioxide particle dispersion liquid into the stirring tank with an ultrasonic spraying device (commercially available) and stir evenly; During the stirring process, heat the temperature to 60 °C, mix for 1 hour, and add to a differential co-rotating twin-screw extruder to extrude and pelletize to obtain a high-efficiency Rayleigh scattering material masterbatch; Preparation of light diffusing agent: Mix 15 parts of inorganic material transparent particles of silicon dioxide, 100 parts of deionized water and 6 parts of polycarboxylate dispersant, and grind them with a nano sand mill to obtain a water-based dispersion liquid of transparent silicon dioxide particles with a D90 value of the nano particle size distribution range of 100 nm; Preparation of light diffusing agent masterbatch: Take 100 parts of the PMMA resin and 3 parts of the water-based dispersion liquid of transparent silicon dioxide particles. First, add 100 parts of the PMMA resin to a stirring tank, and then spray the water-based dispersion liquid of transparent silicon dioxide particles into the stirring tank with an ultrasonic spraying device (commercially available) and stir evenly; During the stirring process, heat the temperature to 60 °C, mix for 1 hour, and add to a differential co-rotating twin-screw extruder to extrude and pelletize to obtain a light diffusing agent masterbatch; Extrusion molding: Mix the Rayleigh scattering material masterbatch: light diffusing agent masterbatch: PMMA resin in a mass ratio of 1:10:100 to obtain a Rayleigh scattering mixture, and use an extrusion press to extrude and mold to obtain a Rayleigh scattering transparent optical sheet.

[0051] Comparative Example 3 As Figures 17 - 18 shown, the brightening layer is at the bottom of the Rayleigh scattering transparent optical composite sheet, and a light guide powder is added to the brightening layer.

[0052] Preparation of Rayleigh scattering agent: Mix 10 parts of titanium dioxide particles, 100 parts of deionized water and 3 parts of silane coupling agent modified dispersant, and grind them with a nano sand mill to obtain a water-based nano titanium dioxide particle dispersion liquid with a D90 value of the nano particle size distribution range of 115 nm; Preparation of Rayleigh scattering material masterbatch: Take 100 parts of the PMMA resin and 0.1 part of the water-based nano dispersion liquid of titanium dioxide material particles. First, add 100 parts of the PMMA resin to a stirring tank, and then spray the water-based nano dispersion liquid of titanium dioxide material particles into the stirring tank with an ultrasonic spraying device (commercially available) and stir evenly; During the stirring process, heat the temperature to 60 °C, mix for 1 - hour, and add to a differential co-rotating twin-screw extruder to extrude and pelletize to obtain a Rayleigh scattering material masterbatch; Preparation of light diffusing agent: 15 parts of inorganic material transparent particles of silica, 100 parts of deionized water and 6 parts of polycarboxylate dispersant are mixed and ground by a nano sand mill to obtain an aqueous dispersion of silica transparent particles with a D90 value of the nano particle size distribution range of 500 nm; Preparation of light diffusing agent masterbatch: Take 100 parts of the PMMA resin and 3 parts of the aqueous dispersion of silica transparent particles. First, add 100 parts of the PMMA resin to a stirring tank, and then spray the aqueous dispersion of silica transparent particles into the stirring tank with an ultrasonic spraying device (commercially available) and stir evenly; during the stirring process, the heating temperature is 60 °C, the mixing time is 1 hour, and it is added to a differential co-rotating twin-screw extruder for extrusion granulation to obtain a light diffusing agent masterbatch; Co-extrusion composite molding: Mix the Rayleigh scattering material masterbatch and the PMMA resin in a mass ratio of 1:100 to obtain a Rayleigh scattering agent mixture, and mix the light diffusing agent masterbatch and the PMMA resin in a ratio of 1:10. Adopt the co-extrusion composite method to co-extrusion and composite the Rayleigh scattering agent mixture: the light diffusing agent mixture in a mass ratio of 95:5 to obtain a Rayleigh scattering transparent optical composite sheet, with a Rayleigh scattering layer on the upper layer and a light diffusing layer on the lower layer.

[0053] Data measurement: Instruments: Particle size tester (HORIBA SZ-100), Phenom Pure+SED desktop scanning electron microscope from Phenom-World in the Netherlands, SPIC-300 Everfine / spectral color illuminometer, haze meter SG-TH-100 Side-entry type LED strip test device (self-made): Input voltage: 56 V / m, power: 3.36 W / m, current 60 mA, LED chip 2835, lamp bead density 175 pieces / m, brightness 3500 Lm / m, luminous efficacy 1041 Lm / W, color temperature 6500 K; Measure the specifications of the blue sky board: 600 mm X 600 mm X 6 mm; The measured Rayleigh scattering penetration distances of the examples and comparative examples are shown as Figure 19 shown.

[0054] Comparison data table:

[0055] It can be seen from the above chart that: Comparative analysis based on experimental data shows that different material systems have a significant impact on the performance of optical sheets. In the example system, the Rayleigh scattering transparent sheet with an innovative brightening layer structure exhibits multiple advantages: while maintaining the blue light scattering characteristics of large-sized sheets, it realizes an increase in brightness value and maintains excellent optical performance, with low haze and high light transmittance. This synergistic effect stems from the optimized regulation of the light transmission path by the brightening layer, which effectively suppresses unnecessary light loss while enhancing scattering.

[0056] Analysis of the comparative system reveals that: 1. Although the comparative example 1 system maintains the blue light scattering characteristics, due to the lower surface reflectivity compared to the example, the effective light output is limited, the brightness index decreases, and it fails to meet the requirements of commercial applications. This verifies the limitations of the simple Rayleigh scattering structure in terms of light extraction efficiency.

[0057] 2. Comparative example 2 uses a traditional diffusion particle system. Although the reflection density increases, it leads to attenuation of the longitudinal light transmittance. This excessive scattering mechanism increases the haze of the sheet and decreases the light transmittance, proving the destruction of the Rayleigh wavelength selection characteristics by disordered scattering.

[0058] 3. Comparative example 3 uses a Rayleigh scattering plate with a light diffusion layer compounded on the surface layer. Due to the increase in the haze of the sheet and the decrease in the light transmittance of the light, the effective components of Rayleigh scattering are covered, resulting in the sheet turning white and yellowing at a certain distance, which has an interfering effect on the bulk optical properties.

[0059] In summary, through the construction of a precisely regulated brightening layer, the present invention breaks through the technologies of traditional optical sheets in terms of light efficiency and chromaticity stability without sacrificing the wavelength selectivity of Rayleigh scattering characteristics.

[0060] It can be seen from the above chart that: In the example, due to the addition of a brightening layer to the Rayleigh scattering transparent optical sheet, not only is the blue light scattering of the Rayleigh scattering plate maintained in the large-sized sheet, but also the brightness reaches a certain value, with low haze and high light transmittance; in comparative example 1, although the blue light scattering of the Rayleigh scattering plate is maintained, due to the low reflectivity of the light, the light brightness is insufficient; in comparative example 2, due to the addition of a light diffusion particle material to the sheet, the reflection density is increased, affecting the longitudinal light transmittance of the light, resulting in a high haze and low light transmittance of the sheet, weakening the Rayleigh scattering penetration ability, and causing the sheet to turn yellow after passing through a certain distance; in comparative example 3, due to the compounding of a light diffusion layer on the surface layer of the Rayleigh scattering plate, the haze of the sheet increases, the light transmittance is low, covering the effective components of Rayleigh scattering, resulting in the sheet turning white and yellowing at a certain distance.

[0061] Conclusion 1. Compared with traditional double-sided side-lighting blue sky panels (the Rayleigh scattering penetration distance usually does not exceed 300 mm, and it is prone to yellowing at long distances), through fine-tuning the particle size of the Rayleigh scattering agent and adopting advanced uniform dispersion technology in the present invention, the nanoparticles pass through precision grinding equipment and are detected by a nano-particle size measuring instrument, and the dispersed particles are truly refined to the nano level. At the same time, ultrasonic spraying technology is adopted, combined with the stretching and dispersion process of a differential co-rotating twin-screw extruder, to ensure the uniform distribution of the nanoparticles in the base resin. The electron microscope scanning results show that the nanoparticles are evenly embedded in the resin matrix, enabling the Rayleigh scattering transmission distance to exceed 600 mm, effectively eliminating the yellowing phenomenon, and presenting a pure Rayleigh scattering visual effect.

[0062] 2. Significant improvement in brightness enhancement and light efficiency utilization: Aiming at the problems of increased haze and decreased light transmittance caused by micron-sized particles in the prior art, the present invention adds a brightening layer on the upper part of the Rayleigh scattering layer and introduces nano-sized transparent particles (such as silica, fused glass, graphene, etc.). The brightening mechanism of these nanoparticles is mainly reflected in the following aspects: Multiple light scattering: The size of the nano-sized particles is much smaller than the visible light wavelength, causing light to scatter multiple times between the particles, increasing the propagation path and interaction time of light inside the transparent sheet, thereby improving the light utilization rate and reflection efficiency.

[0063] Enhanced interface reflection: There are a large number of tiny interfaces on the surface of the nanoparticles, which can reflect light and superimpose on each other to form stronger reflected light. At the same time, the high surface activity of the nanoparticles helps to form a denser film layer, further enhancing the reflectivity.

[0064] Refractive index matching: By carefully selecting the refractive index of the nanoparticles to match the matrix material of the transparent sheet, the refractive loss of light at the interface between the particles and the matrix is reduced, thereby improving the light transmittance and reflection efficiency.

[0065] 3. Environmental protection and process simplification The present invention abandons the use of toxic solvents such as xylene and the risks of harming health and the environment in the prior art, and adopts an aqueous nano-dispersion (such as a deionized water-based solvent), avoiding the use of toxic substances, and the process is safer and more environmentally friendly. At the same time, technologies such as co-extrusion molding, ultrasonic spray dispersion, and extrusion by a differential co-rotating twin-screw extruder simplify the production process, reduce energy consumption and costs, and are suitable for large-scale industrial production.

[0066] 4. Significant optimization of scratch resistance and durability Through an innovative hardening layer design and the use of a silicone resin coating technology containing nano-silica, the present invention significantly improves the surface hardness, abrasion resistance, and antistatic properties of the board, thereby greatly extending its service life. Existing boards generally suffer from insufficient surface hardness, easy scratching, and lack of antistatic function, resulting in easy dust adsorption on the surface, affecting the Rayleigh scattering effect, and thus reducing the visual experience. To address these issues, the present invention realizes excellent scratch resistance and long-term antistatic and dust-proof performance through an immersion coating and curing technology, fully meeting the long-term use requirements.

[0067] 5. Optical Performance Stability and Consistency In the prior art, uneven dispersion of micron-sized particles leads to unstable light spot or scattering effects. The present invention uses a nano sand mill grinding and ultrasonic spray dispersion technology, and a differential co-rotating twin-screw extruder extrusion dispersion technology to ensure that nano particles are evenly distributed in the resin matrix. Combined with strict mass ratios (such as the ratio of Rayleigh scattering agent being one in ten million to one in one hundred thousand), the optical performance consistency of large-sized boards (≥600mm) is achieved, reducing the production defective rate.

[0068] 6. Market Competitiveness and Multifunctional Applications The board of the present invention combines Rayleigh scattering, brightness enhancement, high light transmittance, and scratch resistance, and can be widely applied to fields such as lighting, display, and decoration (such as blue sky lights, advertising light boxes). Its unique visual effects and environmental protection characteristics significantly increase the product added value, meet the high-end market's demand for high-quality optical materials, and enhance the enterprise's market competitiveness.

[0069] 7. Analysis of Optical Mechanisms: Rayleigh Scattering Mechanism: High refractive index inorganic nano materials are used as Rayleigh scattering agents, and through advanced dispersion technologies and processes, they are ensured to be evenly dispersed in the resin matrix. These nano particles undergo Rayleigh scattering under light irradiation, effectively enhancing the distance and penetration ability of Rayleigh scattering.

[0070] Brightening Layer Mechanism: As mentioned above, the nano-sized transparent particles in the brightening layer significantly enhance the light reflection and brightening effect through mechanisms such as multiple scattering, interface reflection enhancement, and refractive index matching. The combined action of these mechanisms enables the transparent board to achieve a significant increase in brightness while ensuring high light transmittance.

[0071] In the process of preparing large-sized transparent optical boards, the present invention optimizes the Rayleigh scattering efficiency and brightness performance by finely regulating the types, ratios, and particle size distributions of Rayleigh scattering agents and brightness enhancers. The Rayleigh scattering layer uses high refractive index inorganic nano materials as scattering agents, and through advanced dispersion technologies and processes, they are ensured to be evenly dispersed in the resin matrix. The brightening layer further enhances the light reflection and brightening effect by introducing inorganic nano material transparent particles with refraction and reflection functions and combining the above brightening mechanism.

[0072] In summary, through material formula innovation, structure optimization, and process improvement, the present invention has successfully solved the core problems in the prior art. Meanwhile, it has the advantages of brightness enhancement, improved dust-proof durability, and environmental friendliness, demonstrating significant technological progress and application value. The detailed elaboration of the brightness enhancement mechanism provides deeper theoretical support for understanding the high performance of the present invention.

[0073] Although the embodiments of the present invention have been shown and described, those of ordinary skill in the art can understand that various changes, modifications, substitutions, and variations can be made to these embodiments without departing from the principles and spirit of the present invention. The scope of the present invention is defined by the appended claims and their equivalents.

Claims

1. A large-sized transparent optical sheet with high-efficiency Rayleigh scattering and brightness enhancement, characterized in that: It is a composite sheet composed of the following three-layer structure: Upper brightening layer: containing a base resin and a brightness enhancer; Middle Rayleigh scattering layer: containing a base resin and a Rayleigh scattering agent; Lower hardening layer: A material with high hardness and not easily brittle is coated on the surface of the transparent optical sheet through an immersion coating process; For the said sheet, in the way of two-way side entry of light, the Rayleigh scattering penetration distance ≥ 600 mm, the haze value ≤ 2%, and the light transmittance ≥ 88%; The said Rayleigh scattering agent is an aqueous nanoparticle dispersion in which specially treated inorganic material nanoparticles with a high refractive index are uniformly dispersed in water; The said brightness enhancer is an aqueous nanoparticle dispersion in which inorganic material transparent nanoparticles with refractive and reflective functions are uniformly dispersed in water; The said hardening layer is coated with a scratch-resistant, wear-resistant and antistatic coating on the surface of the transparent optical sheet through an immersion coating process.

2. An efficient large-size transparent optical sheet for Rayleigh scattering and brightness enhancement according to claim 1, characterized in that: The said base resin is selected from transparent resins with high light transmittance, low light absorption and good processing performance, including polymethyl methacrylate (PMMA), polycarbonate (PC), polystyrene (PS) or their copolymers; polyethylene terephthalate (PET), cycloolefin copolymer (COC / COP), transparent modified PP, polyethersulfone (PES) & polysulfone (PSU), polyethylene naphthalate (PEN), transparent thermoplastic polyurethane (TPU), one or more of them; The said inorganic material nanoparticles with a high refractive index include one or more of zinc selenide, zinc sulfide, chromium oxide, bismuth vanadate, titanium dioxide, and inorganic materials such as silicon dioxide (low refractive index material); The said inorganic material transparent nanoparticles include one or more of silicon dioxide, fused quartz, and graphene.

3. The preparation method of a large-size transparent optical sheet with high-efficiency Rayleigh scattering and brightness enhancement according to any one of claims 1-2, characterized in that: It includes the following steps: S1. Prepare the Rayleigh scattering agent: Mix 10 - 15 parts of inorganic material particles with a high refractive index, 100 parts of deionized water, and 3 - 10 parts of an aqueous dispersant for inorganic material particles, and grind them with a nano sand mill to obtain an aqueous nanoparticle dispersion with a nanoparticle size distribution range D90 of 50 nm - 110 nm; S2. Prepare the brightness enhancer: Mix 15 - 25 parts of inorganic material transparent particles, 100 parts of deionized water, and 6 - 15 parts of an aqueous dispersant for inorganic material transparent particles, and grind them with a nano sand mill to obtain an aqueous nanoparticle dispersion of inorganic material transparent particles with a nanoparticle size distribution range D90 of 60 nm - 110 nm; S3. Prepare the masterbatch of the high-efficiency Rayleigh scattering layer material: Take 100 parts of the said base resin and 0.1 - 0.5 part of the Rayleigh scattering agent. First, add 100 parts of the base resin to a stirring tank, and then spray the Rayleigh scattering agent into the stirring tank with an ultrasonic spray device (commercially available) and stir evenly; during the stirring process, heat the temperature to 60 - 100 °C, mix for 1 - 2 hours, and add it to a differential co-rotating twin-screw extruder to extrude and pelletize to obtain the masterbatch of the high-efficiency Rayleigh scattering layer material; S4. Preparation of the masterbatch of the brightening layer material: Take 100 parts of the base resin and 3 - 8 parts of the brightness enhancer. First, add 100 parts of the base resin to a stirring tank, and then spray the brightness enhancer into the stirring tank using an ultrasonic spraying device (commercially available) and stir evenly. During the stirring process, the heating temperature is 60 - 100 °C, the mixing time is 1 - 2 hours, and then it is added to a differential co-rotating twin-screw extruder for extrusion granulation to obtain the masterbatch of the brightening layer material; S5. Co-extrusion composite molding: Mix the masterbatch of the high-efficiency Rayleigh scattering layer material and the base resin according to the mass ratio of the high-refractive-index inorganic material nanoparticles in the high-efficiency Rayleigh scattering layer ranging from one in ten million to one in one hundred thousand parts to obtain the high-efficiency Rayleigh scattering layer material. Mix the masterbatch of the brightening layer material and the base resin according to the mass ratio of the inorganic material transparent nanoparticles in the brightening layer ranging from one in one million to one in ten thousand to obtain the brightening layer material. Adopt the co-extrusion composite method to co-extrusion and composite the two (the high-efficiency Rayleigh scattering layer material and the brightening layer material) according to the mass ratio of 90 - 95:10 - 5 parts to obtain a large-size transparent optical composite sheet with high-efficiency Rayleigh scattering and brightness enhancement; S6. Post-treatment of the hardening layer: Perform immersion coating treatment on the formed sheet to enhance its surface hardness and anti-static property, keep the plate surface clean and dust-proof, and further improve the brightness.

4. The preparation method of a large-size transparent optical sheet with high-efficiency Rayleigh scattering and brightness enhancement according to claim 3, characterized in that: The aqueous dispersant of the inorganic material particles: one or more of polycarboxylate dispersants, anionic phosphate ester dispersants, and silane coupling agent-modified dispersants; The aqueous dispersant of the inorganic material transparent particles: one or more of polycarboxylate dispersants, phosphate dispersants, and non-ionic surfactants.

5. The preparation method of a large-sized transparent optical sheet with high-efficiency Rayleigh scattering and brightness enhancement according to claim 3, characterized in that: The preparation method of the hardening layer includes the following steps: S5.

1. Preparation of the dispersion liquid of the hardening layer nanoparticle material: Mix 5 - 10 parts of silica material particles, 100 parts of isopropyl alcohol, 3 - 10 parts of an oily dispersant, and 1 - 5 parts of a transparent antistatic agent, and add them to a nano sand mill for grinding for 3 - 6 hours to obtain a dispersion liquid of the hardening layer nanoparticle material with the nanoparticle size distribution range D90 of 60 nm - 100 nm; S5.

2. Preparation of the immersion coating nanoparticle solution of the hardening layer: The formula of the immersion coating nanoparticle solution: 100 parts of organosilicon resin - polyalkylaryl organosilicon resin, 0.2 - 2 parts of the dispersion liquid of the hardening layer nanoparticle material, 2 - 5 parts of a surfactant, 2 - 5 parts of a crosslinking agent (silane coupling agent), 0.1 - 1 part of a catalyst (acid / base), an appropriate amount of solvent, etc.; S5.

3. Preparation: a. Add the organosilicon resin to the solvent and stir evenly; add the nanoparticle dispersion liquid, and use ultrasonic dispersion or mechanical stirring to ensure that the nanoparticles are evenly dispersed; add the surfactant and continue stirring; add the crosslinking agent and the catalyst and stir evenly to form a stable coating solution; b. Immersion coating Immerse the pretreated substrate into the prepared coating solution, and adjust the immersion time according to the substrate material and the coating thickness requirements, usually 1 - 10 minutes; the substrate can be gently shaken during the immersion process to ensure that the solution evenly covers the surface; c. Pull-up film formation Slowly lift the substrate out of the solution at a constant speed to form a uniform liquid film; d. Pre-drying: Pre-dry the coated substrate at room temperature or low temperature (such as 50 - 80 °C) to volatilize the solvent and form a preliminary coating; e. Curing treatment Put the pre-dried substrate into an oven and cure it at an appropriate temperature (such as 60 - 80 °C) for 30 - 60 minutes to allow the silicone resin to fully react with the cross-linking agent and form a dense coating.

6. The preparation method of a large-sized transparent optical sheet with high-efficiency Rayleigh scattering and brightness enhancement according to claim 5, characterized in that: In the step S5.1, The oil-based dispersant: includes polyurethane dispersants and acrylic dispersants; The transparent antistatic agent: includes polymer antistatic agents, inorganic salt antistatic agents, silicone antistatic agents, carbon-based antistatic agents, composite antistatic agents, and nano antistatic agents.

7. A method for preparing a large-sized transparent optical sheet with high-efficiency Rayleigh scattering and brightness enhancement according to claim 5, characterized in that: In the step S5.2, The catalyst (acid / base): includes p-toluenesulfonic acid (p-TSA), hydrochloric acid (HCl), ammonia water (NH4OH), sodium hydroxide (NaOH), or potassium hydroxide (KOH); The surfactant: includes non-ionic surfactants, anionic surfactants, and cationic surfactants.

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