Composite heat-resistant diffusion plate and preparation process thereof

Abstract

The present invention relates to the technical field of diffuser plate preparation, and more particularly to a composite heat-resistant diffuser plate and a preparation process thereof. The diffuser plate comprises, from bottom to top, a core layer, an intermediate layer, and a surface layer. The intermediate layer comprises the following components by mass: 55-60 parts of polyethylene terephthalate, 30-40 parts of polybutylene terephthalate, 1.5-2 parts of a titanate coupling agent, 5-8 parts of chopped glass fibers, 5-7 parts of a phosphorus-based flame retardant, and 0.5-1 parts of maleic anhydride-grafted SEBS. The composite heat-resistant diffuser plate provided by the present invention exhibits significant advantages in terms of heat resistance, mechanical properties, optical properties, and environmental friendliness through innovative material selection, multi-layer structure design, and precise process control, and has significant application prospects.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of diffusion plate preparation, in particular to a composite heat-resistant diffusion plate and a preparation process thereof. BACKGROUND

[0002] As a core component of liquid crystal display, LED lighting and imaging system, the core function of the diffusion plate is to achieve uniform and soft lighting effect by scattering incident light. At present, general polystyrene (GPPS) is the mainstream substrate for manufacturing optical diffusion plates, but it has significant defects: insufficient heat resistance (heat distortion temperature is usually lower than 80℃) and poor impact resistance (notch impact strength <2kJ / m²). In a long-term high-temperature working environment, GPPS-based diffusion plates are prone to thermal deformation, resulting in degradation of optical performance and even failure; during transportation or installation, external impact is easy to cause brittle fracture, resulting in a significant reduction in yield and service life.

[0003] In recent years, polyester materials have been considered as potential alternative substrates for preparing diffusion plates instead of polystyrene (GPPS) due to their excellent comprehensive performance. Taking polybutylene terephthalate (PBT resin) as an example, PBT is obtained by polycondensation of terephthalic acid and 1,4-butanediol, and the linear structure containing ester bonds in the main chain endows it with high melting point (225-230℃), low water absorption rate (<0.1%) and excellent chemical corrosion resistance, and no stress cracking risk, outstanding long-term thermal aging stability. However, existing research has not yet achieved effective application of PBT in the field of light diffusion plates. Experiments show that the light diffusion effect of the diffusion plate prepared by directly replacing GPPS with PBT is significantly reduced, the main reasons of which include: first, refractive index mismatch, the difference between PBT resin (refractive index 1.55) and traditional glass beads (refractive index 1.50-1.53) leads to reduced light scattering efficiency; second, poor interfacial compatibility, conventional light diffusers (such as inorganic particles) are prone to agglomeration in the PBT matrix, uneven distribution causes haze fluctuation (deviation >20%) and light transmittance decrease (<80%).

[0004] Therefore, it is necessary to make a diffusion plate that can solve the above-mentioned shortcomings of the diffusion plate, which not only has great environmental significance, but also has high economic value.

[0005] PURPOSE OF THE INVENTION

[0006] In order to overcome the deficiencies in the prior art, the purpose of the present application is to provide a kind of composite heat-resistant diffusion plate and its preparation process, the diffusion plate includes core layer, intermediate layer, surface layer three layer structures from bottom to top, wherein intermediate layer includes the following components by mass fraction:55-60 parts of polyethylene terephthalate, 30-40 parts of polybutylene terephthalate, 1.5-2 parts of titanate coupling agent, 5-8 parts of short glass fiber, 5-7 parts of phosphorus flame retardant, 0.5-1 parts of maleic anhydride graft SEBS.The composite heat-resistant diffusion plate provided by the present application shows significant advantages in heat resistance, mechanical properties, optical properties and environmental protection, etc., and has significant application prospect through innovative material selection, multi-layer structure design and precise process control.

[0007] In order to achieve the above-mentioned purpose, the present application provides the following technical solutions:

[0008] A kind of composite heat-resistant diffusion plate, from bottom to top includes core layer, intermediate layer, surface layer;

[0009] The core layer includes the following components by mass fraction:40-50 parts of bisphenol A type unsaturated polyester, 10-20 parts of polybutylene succinate, 5-7 parts of glass bead, 1.2-1.5 parts of dicumyl peroxide, 3-5 parts of nano cerium oxide, 0.8-1 parts of kaolin;

[0010] The intermediate layer includes the following components by mass fraction:55-60 parts of polyethylene terephthalate, 30-40 parts of polybutylene terephthalate, 1.5-2 parts of titanate coupling agent, 5-8 parts of short glass fiber, 5-7 parts of phosphorus flame retardant, 0.5-1 parts of maleic anhydride graft SEBS;

[0011] The surface layer includes the following components by mass fraction:30-40 parts of polyethylene terephthalate-1,4-cyclohexane dimethanol, 3-5 parts of nano boron nitride, 8-10 parts of silicone-based light diffuser, 1.5-2 parts of antioxidant, 3.5-4 parts of modified compatibilizer.

[0012] Preferably, the maleic anhydride graft SEBS is prepared by the following steps:

[0013] S11.80-100 parts of SEBS are dissolved in 500-600 parts of toluene solution with a mass concentration of 10-20% by mass fraction, and stirred uniformly to form a uniform solution;

[0014] S12.5-8 parts of maleic anhydride and 0.3-1 parts of benzoyl peroxide are added to the solution treated in step S11 in turn, stirred uniformly, and then heated to 110-130℃ under nitrogen protection, and reacted for 3-6h to prepare a reaction solution;

[0015] S13. The reaction solution is used to precipitate the polymer with acetone, washed with ethanol for 3-4 times, and dried at 60-80℃ under vacuum until constant weight to obtain the maleic anhydride grafted SEBS.

[0016] Preferably, the modified compatilizer is prepared by the following steps:

[0017] S21. 60-80 parts of ethylene-vinyl acetate copolymer is dissolved in 400-500 parts of toluene solution with a mass concentration of 10-20%, and stirred uniformly to form a uniform solution;

[0018] S22. 5-8 parts of glycidyl methacrylate and 0.5-1.5 parts of benzoyl peroxide are sequentially added to the solution treated in step S21, and stirred uniformly, then heated to 110-130℃ under oil bath heating under nitrogen protection, and reacted for 4-8h to obtain a modified compatilizer solution;

[0019] S23. The modified compatilizer solution is used to precipitate the polymer with methanol, washed with ethanol for 3-4 times, and dried at 60-80℃ under vacuum until constant weight to obtain the modified compatilizer.

[0020] Preferably, the particle size of the glass beads is 15-45μm; and the particle size of the kaolin is 1.5-3μm.

[0021] Preferably, the titanate coupling agent is further limited to a monoalkyloxy diphosphate type coupling agent.

[0022] Preferably, the length of the chopped glass fiber is 2.5-3.5mm, and the diameter is 10-13μm; and the phosphorus-based flame retardant is further limited to a phosphate-based flame retardant.

[0023] Preferably, the silicone-based light diffuser is further limited to an organic silicon composite light diffuser; and the antioxidant is selected from one or more of tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid]pentaerythritol ester and β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate octadecyl ester.

[0024] A preparation process of a composite heat-resistant diffusion plate, for producing the composite heat-resistant diffusion plate, comprising the following steps:

[0025] S1. Raw material premixing: the raw materials of the core layer, the intermediate layer, and the surface layer are respectively put into a high-speed mixer for mixing and stirring for 10-20min for premixing to obtain the core layer premix, the intermediate layer premix, and the surface layer premix;

[0026] S2. Extrusion granulation: the core layer premix and the intermediate layer premix are respectively extruded and granulated through a double-screw extruder, and the surface layer premix is extruded and granulated through a single-screw extruder to obtain the core layer granules, the intermediate layer granules, and the surface layer granules.

[0027] S3. Compression molding: the core layer particles and the intermediate layer particles are respectively put into a double screw extruder, and the surface layer particles are put into a single screw extruder to melt and form three layers of co-extrusion and compression molding to obtain the composite heat-resistant diffusion plate.

[0028] Preferably, in step S2, the temperature of each zone of the double screw extruder for preparing the core layer particles is: the first zone is 160-180℃, the second zone is 190-200℃, the third zone is 210-220℃, and the die temperature is 215-220℃;

[0029] The temperature of each zone of the double screw extruder for preparing the intermediate layer particles is: the first zone is 240-250℃, the second zone is 260-270℃, the third zone is 260-265℃, and the die temperature is 265-270℃;

[0030] The temperature of each zone of the single screw extruder for preparing the surface layer particles is: the first zone is 200-210℃, the second zone is 220-230℃, the third zone is 230-240℃, and the die temperature is 225-230℃.

[0031] Preferably, in step S3, the temperature of each zone of the double screw extruder for melting the core layer particles is: the first zone is 190-200℃, the second zone is 210-220℃, and the die temperature is 205-210℃;

[0032] The temperature of each zone of the double screw extruder for melting the intermediate layer particles is: the first zone is 260-270℃, the second zone is 275-280℃, and the die temperature is 265-270℃;

[0033] The temperature of each zone of the single screw extruder for melting the surface layer particles is: the first zone is 220-230℃, the second zone is 235-240℃, and the die temperature is 235-240℃.

[0034] Compared with the prior art, the present application has the following beneficial effects:

[0035] 1. The core layer adopts a crosslinking system of bisphenol A type unsaturated polyester and polybutylene succinate, and a three-dimensional network structure is constructed through a free radical initiator, which significantly improves the thermal stability and anti-variation ability of the material; the synergistic effect of glass microbeads and nano cerium oxide enhances the rigidity of the matrix while delaying photoaging through refractive index matching and ultraviolet absorption mechanism;

[0036] 2. The intermediate layer is reinforced by the combination of polyester alloy matrix and chopped glass fibers, combined with the gas phase-coagulation phase synergistic flame retardant mechanism of phosphorus-based flame retardant, while maintaining high light transmittance, realizing high efficient flame retardation; the maleic anhydride grafted SEBS effectively improves the interfacial compatibility of fibers and resin through the physical entanglement and chemical bonding of polar functional groups and polyester molecular chains, and inhibits mechanical failure caused by stress concentration;

[0037] 3. The surface layer is based on the scattering phase regulation of organic silicon composite light diffuser and the hard phase enhancement of nano boron nitride, which improves the surface wear resistance on the premise of ensuring uniform light diffusion; the antioxidant inhibits thermal oxidative degradation through the free radical capture and peroxide decomposition mechanism, and the modified compatibilizer realizes the chemical bond bridging between layers through the reaction of epoxy groups and polyester end groups, ensuring the interfacial bonding strength of the multilayer structure;

[0038] 4. The present application realizes the balanced improvement of heat resistance, impact resistance and optical performance by the layered granulation and gradient temperature control co-extrusion technology, so that the materials in each layer are closely matched to form a stable composite structure during extrusion molding; at the same time, the whole production process uses environmentally friendly materials, which do not contain harmful substances such as halogen, so that the product is safe and durable. BRIEF DESCRIPTION OF DRAWINGS

[0039] Fig. 1 The preparation process flow chart of the composite heat-resistant diffusion plate is provided in the present application;

[0040] Fig. 2 The preparation process flow chart of the maleic anhydride grafted SEBS is provided in the present application;

[0041] Fig. 3 The preparation process flow chart of the modified compatibilizer is provided in the present application. DETAILED DESCRIPTION

[0042] The present application will be described in detail below with reference to the embodiments thereof, obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0043] Please refer to Figs. 1-3 , the present application provides a technical solution:

[0044] Example 1

[0045] A preparation process of a composite heat-resistant diffusion plate:

[0046] S1. Raw material premixing: according to mass fraction, the raw materials of core layer, intermediate layer and surface layer are respectively put into high-speed mixer for mixing and stirring for 10 min for premixing, to obtain the corresponding core layer premix, intermediate layer premix and surface layer premix;

[0047] S2. Extrusion granulation: the core layer premix and the intermediate layer premix are respectively extruded and granulated by a double screw extruder, and the surface layer premix is extruded and granulated by a single screw extruder, to obtain core layer particles, intermediate layer particles and surface layer particles;

[0048] S3. Imprint forming: the core layer particles and the intermediate layer particles are respectively put into a double screw extruder, and the surface layer particles are put into a single screw extruder to melt and co-extrude three layers and then to be imprinted and formed, to obtain the composite heat-resistant diffusion plate.

[0049] In the above process, in step S2, the temperature of each zone of the double screw extruder for preparing the core layer particles is: the first zone is 160℃, the second zone is 190℃, the third zone is 210℃, and the die temperature is 215℃;

[0050] The temperature of each zone of the double screw extruder for preparing the intermediate layer particles is: the first zone is 240℃, the second zone is 260℃, the third zone is 265℃, and the die temperature is 270℃;

[0051] The temperature of each zone of the single screw extruder for preparing the surface layer particles is: the first zone is 210℃, the second zone is 220℃, the third zone is 230℃, and the die temperature is 230℃;

[0052] In the above process, in step S3, the temperature of each zone of the double screw extruder for melting the core layer particles is: the first zone is 190℃, the second zone is 210℃, and the die temperature is 205℃;

[0053] The temperature of each zone of the double screw extruder for melting the intermediate layer particles is: the first zone is 260℃, the second zone is 275℃, and the die temperature is 265℃;

[0054] The temperature of each zone of the single screw extruder for melting the surface layer particles is: the first zone is 220℃, the second zone is 235℃, and the die temperature is 240℃;

[0055] In the above process, the technical effect of the three-layer co-extrusion is achieved by a T-shaped clothes hanger type co-extrusion die, the flow channel is designed according to the ratio of core layer: intermediate layer: surface layer = 45%: 35%: 20%, the die lip gap tolerance is ±0.02mm, and the pulling speed is 5m / min; the working parameters of the imprint forming are: die pressure 18MPa, traction roller pressure 0.8MPa, and cooling water temperature 15℃;

[0056] In the above process, after the composite heat-resistant diffusion plate is prepared, it can also be annealed by 140℃ hot air circulation for 1h to eliminate the internal stress in the diffusion plate;

[0057] In the above process, the core layer raw material includes the following components by mass fraction (wherein the mass of one mass fraction is 500g):

[0058]

[0059] The brand of the bisphenol A type unsaturated polyester is UPGF-90;

[0060] The polybutylene succinate is purchased from Mitsubishi Chemical Corporation;

[0061] The glass microbeads have a particle size of 15-45μm, a model of iM30K, and are purchased from PQ Corp;

[0062] The nano cerium oxide has a particle size of 0.4-0.8μm;

[0063] The kaolin has a particle size of 1.5-3μm;

[0064] In the above process, the intermediate layer raw material includes the following components by mass fraction (wherein the mass of one mass fraction is 500g):

[0065]

[0066] In the above process, the polyethylene terephthalate has a brand of Rynite®935;

[0067] In the above process, the polybutylene terephthalate has a brand of SK605;

[0068] The titanate coupling agent is further limited to a monoalkyloxy pyrophosphoric acid ester type coupling agent, specifically PN-201;

[0069] The short glass fiber has a fiber length of 3mm and a diameter of 11μm, a model of ECS303-3H;

[0070] The phosphorus type flame retardant is further limited to a phosphate type flame retardant, specifically resorcinol bisphosphate;

[0071] The maleic anhydride grafted SEBS is prepared by the following preparation method:

[0072] S11. 80 parts of SEBS are dissolved in 500 parts of a toluene solution with a mass concentration of 10% by mass fraction, and stirred uniformly to form a uniform solution;

[0073] S12. 5 parts of maleic anhydride and 0.3 parts of benzoyl peroxide are sequentially added to the solution treated in step S11, and stirred uniformly, and then heated to 110°C in an oil bath under nitrogen protection for 3h to prepare a reaction liquid;

[0074] S13. The reaction solution is precipitated with excess acetone, washed with ethanol three times, and dried at 60°C under vacuum to constant weight to obtain the maleic anhydride grafted SEBS;

[0075] In the above process, the SEBS is model 6151 from Taiwan Xiu;

[0076] In the above process, the surface layer raw material includes the following components by mass fraction (wherein the mass of one mass fraction is 500g):

[0077]

[0078] The polyethylene terephthalate-1,4-cyclohexane dimethanol is model PCTG VX401;

[0079] The silicone-based light diffuser is further defined as an organic silicon composite light diffuser, and the specific model is X-52-7056A;

[0080] The antioxidant is tetra[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionic acid] pentaerythritol ester;

[0081] The modified compatibilizer is prepared by the following steps:

[0082] S21. 60 parts of ethylene-vinyl acetate copolymer are dissolved in 400 parts of toluene solution with a mass concentration of 10% by mass fraction, and stirred uniformly to form a uniform solution;

[0083] S22. 5 parts of glycidyl methacrylate and 0.5 parts of benzoyl peroxide are sequentially added to the solution treated in step S21, and after stirring uniformly, the solution is heated to 110°C in an oil bath under nitrogen protection, and reacted for 4h to obtain a modified compatibilizer solution;

[0084] S23. The modified compatibilizer solution is precipitated with excess methanol, washed with ethanol three times, and dried at 60°C under vacuum to constant weight to obtain the modified compatibilizer;

[0085] In the above process, the ethylene-vinyl acetate copolymer is purchased from Mitsubishi Chemical Corporation.

[0086] Example 2: Example 2 differs from Example 1 in that in Example 2, the core layer raw material includes the following components by mass fraction (wherein the mass of one mass fraction is 500g):

[0087]

[0088] The intermediate layer raw material includes the following components by mass fraction (wherein the mass of one mass fraction is 500g):

[0089]

[0090] The surface layer raw material includes the following components by mass parts (wherein the mass of one mass part is 500 g) respectively:

[0091]

[0092] The remaining steps are identical to those in Example 1.

[0093] Example 3: Example 3 differs from Example 1 in that, in Example 3, the core layer raw material includes the following components by mass parts (wherein the mass of one mass part is 500 g) respectively:

[0094]

[0095] The intermediate layer raw material includes the following components by mass parts (wherein the mass of one mass part is 500 g) respectively:

[0096]

[0097] The surface layer raw material includes the following components by mass parts (wherein the mass of one mass part is 500 g) respectively:

[0098]

[0099] The remaining steps are identical to those in Example 3.

[0100] Example 4: Example 4 differs from Example 1 in that, in Example 4, the core layer raw material includes the following components by mass parts (wherein the mass of one mass part is 500 g) respectively:

[0101]

[0102] The intermediate layer raw material includes the following components by mass parts (wherein the mass of one mass part is 500 g) respectively:

[0103]

[0104] The surface layer raw material includes the following components by mass parts (wherein the mass of one mass part is 500 g) respectively:

[0105]

[0106] The remaining steps are identical to those in Example 4.

[0107] Comparative Example

[0108] Comparative Example 1: Comparative Example 1 has the following difference from Example 1, the difference is only that in Comparative Example 1, the preparation of the core layer is cancelled, and the rest of the steps are exactly the same in Comparative Example 1 and Example 1.

[0109] Comparative Example 2: Comparative Example 2 has the following difference from Example 1, the difference is only that in Comparative Example 2, the preparation of the surface layer is cancelled, and the rest of the steps are exactly the same in Comparative Example 2 and Example 1.

[0110] Comparative Example 3: Comparative Example 3 has the following difference from Example 1, the difference is only that in Comparative Example 3, the preparation of the core layer and the surface layer is cancelled, and the rest of the steps are exactly the same in Comparative Example 3 and Example 1.

[0111] Performance test:

[0112] According to the requirements of GB / T 2410-2008, GB / T 2410-2008 standards, the light transmittance and haze of the prepared composite heat-resistant diffusion plate were tested; according to the requirements of GB / T 1843-2008, GB / T 9341-2008 standards, the notched impact strength and bending strength of the prepared composite heat-resistant diffusion plate were tested; according to the requirements of GB / T 1634.2-2019, GB / T 2423.3-2016 standards, the heat deformation temperature and long-term heat resistance of the prepared composite heat-resistant diffusion plate were tested; according to the requirements of GB / T 2408-2021 standards, the flame retardant performance of the prepared composite heat-resistant diffusion plate was tested, and the test results are as follows:

[0113]

[0114] According to the performance test data of Examples 1-4, the light transmittance is higher than 87%, the haze is higher than 91%, the notched impact strength is higher than 45kJ / m², the bending strength is higher than 118MPa, the HDT is higher than 158℃, the heat-resistant light retention rate is higher than 90%, and the UL94 vertical burning grade reaches V-0, which has excellent and stable performance, which proves that the composite heat-resistant diffusion plate provided by the present application has obvious application prospect by innovative material selection, multi-layer structure design and precise process control in terms of heat resistance, mechanical properties, optical properties and environmental protection.

[0115] The light transmittance and haze of Examples 1-4 are significantly better than those of Comparative Examples 1-3, because the layered design synergistically regulates the optical properties. In the Examples, the rigid skeleton is formed by the crosslinked network of bisphenol A unsaturated polyester (UPGF-90) and polybutylene succinate (PBS) in the core layer. The glass microbeads (15-45 pm) and nano cerium oxide (0.4-0.8 pm) achieve directional scattering of light by refractive index matching (core layer resin refractive index 1.56, glass microbeads 1.52), while the nano cerium oxide absorbs ultraviolet band (200-400 nm) energy to inhibit photodegradation and ensure long-term light transmittance retention (90.8%-93.5%). In Comparative Example 1 (without a core layer), the light directly penetrates the middle layer, resulting in Fresnel reflection loss due to the difference between the PET / PBT matrix (refractive index 1.57) and the air interface (refractive index 1.0), which leads to a decrease in light transmittance to 78.3%. In addition, the lack of UV shielding effect of nano cerium oxide results in a light transmittance retention rate of only 68.5% after long-term humid heat aging.

[0116] The notched impact strength and flexural strength of Examples 1-4 are significantly better than those of Comparative Examples 1-3. It is speculated that the reason is the synergistic toughening mechanism of the interface between the core layer and the middle layer. PBS as an elastic phase in the core layer disperses impact energy through molecular chain entanglement, while the maleic anhydride grafted SEBS (grafting rate ≥1.5%) in the middle layer forms chemical bonds by reacting with the terminal hydroxyl groups of PET / PBT through anhydride groups, enhancing the interfacial bonding force between the glass fiber (ECS303-3H) and the resin and inhibiting crack propagation. In Example 2, for example, the PBS content is increased to 15 parts, and the plasticizing effect increases the impact strength to 51.2 kJ / m². In Comparative Example 3, the core layer and the surface layer are completely missing, and the physical enhancement of the middle layer glass fiber (5-8 parts) is relied on. There are weak bonding zones between the glass fiber and the resin, and stress concentration leads to a flexural strength of only 72 MPa.

[0117] The heat distortion temperature of Examples 1-4 is significantly higher than that of Comparative Examples 1-3. This is because the rigid structure of the benzene ring and the crosslinked network (DCP induced free radical crosslinking) of the bisphenol A resin in the core layer restricts the movement of molecular chains, while the phosphorus-based flame retardant (resorcinol bisphosphate) in the middle layer generates a phosphate ester coke layer during combustion, which insulates oxygen and catalyzes the dehydration of PET / PBT to form carbon, achieving UL94 V-0 level flame retardation. In Comparative Example 1, the middle layer flame retardant alone does not form a complete coke layer, and the molten droplets ignite the cotton during vertical burning, only reaching V-2 level. Comparative Example 3 does not pass the flame retardation test.

[0118] Although embodiments of the present application have been shown and described, it is to be understood that various changes, modifications, substitutions and alterations can be made to these embodiments without departing from the principles and spirit of the present application. The scope of the present application is defined by the appended claims and their equivalents.

Claims

1. A composite heat-resistant diffusion plate, characterized in that: From bottom to top, it includes core layer, middle layer and surface layer; The core layer comprises the following components by mass: 40-50 parts of bisphenol A type unsaturated polyester, 10-20 parts of polybutylene succinate, 5-7 parts of glass microspheres, 1.2-1.5 parts of dicumyl peroxide, 3-5 parts of nano cerium oxide, and 0.8-1 part of kaolin; The intermediate layer comprises the following components in parts by mass: 55-60 parts of polyethylene terephthalate, 30-40 parts of polybutylene terephthalate, 1.5-2 parts of titanate coupling agent, 5-8 parts of chopped glass fiber, 5-7 parts of phosphorus flame retardant, and 0.5-1 part of maleic anhydride grafted SEBS; The surface layer comprises the following components by mass: 30-40 parts of polyethylene terephthalate-1,4-cyclohexanedimethanol, 3-5 parts of nano boron nitride, 8-10 parts of silicone-based light diffuser, 1.5-2 parts of antioxidant, and 3.5-4 parts of modified compatibilizer.

2. The composite heat-resistant diffusion plate according to claim 1, characterized in that: The maleic anhydride grafted SEBS is prepared by the following steps: S11. 80-100 parts by mass of SEBS are dissolved in 500-600 parts by mass of a toluene solution having a concentration of 10-20%, and stirred to form a uniform solution; S12. To the solution treated in step S11, 5-8 parts of maleic anhydride and 0.3-1 parts of benzoyl peroxide were added sequentially, stirred, and heated in an oil bath under nitrogen to 110-130 ° C. for 3-6 hours to obtain a reaction solution; S13. The reaction solution was treated with acetone to precipitate a polymer, which was washed with ethanol 3-4 times and dried under vacuum at 60-80° C. to a constant weight to obtain the maleic anhydride-grafted SEBS.

3. The composite heat-resistant diffusion plate according to claim 1, characterized in that: The modified compatibilizer is prepared by the following steps: S21. 60-80 parts by mass of ethylene - vinyl acetate copolymer was dissolved in 400-500 parts by mass concentration of 10-20% toluene solution, and stirred to form a uniform solution; S22. To the solution treated in step S21, 5-8 parts of glycidyl methacrylate and 0.5-1.5 parts of benzoyl peroxide were added sequentially, stirred, and heated in an oil bath under nitrogen to 110-130 ° C. for 4-8 hours to obtain a modified compatibilizer solution; S23. The modified compatibilizer solution is treated with methanol to precipitate a polymer, which is washed with ethanol 3-4 times and dried under vacuum at 60-80° C. to a constant weight to obtain the modified compatibilizer.

4. The composite heat-resistant diffusion plate according to claim 1, characterized in that: The particle size of the glass microbeads is 15-45 μm; the particle size of the kaolin is 1.5-3 μm.

5. The composite heat-resistant diffusion plate according to claim 1, characterized in that: The titanate coupling agent is further defined as a monoalkoxy pyrophosphate type coupling agent.

6. The composite heat-resistant diffusion plate according to claim 1, characterized in that: The fiber length of the chopped glass fibers is 2.5-3.5 mm, and the diameter is 10-13 μm; the phosphorus-based flame retardant is further limited to a phosphate flame retardant.

7. The composite heat-resistant diffusion plate according to claim 1, characterized in that: The silicone-based light diffuser is further defined as an organosilicon composite light diffuser; the antioxidant is selected from one or more of pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate and octadecylβ-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate.

8. A process for preparing a composite heat-resistant diffusion plate, for producing the composite heat-resistant diffusion plate according to any one of claims 1 to 7, characterized in that: The following steps are involved: S1. Premixing of raw materials: The raw materials of the core layer, the middle layer, and the surface layer are respectively put into a high-pressure mixer and mixed and stirred for 10-20 minutes to obtain the corresponding core layer premix, the middle layer premix, and the surface layer premix; S2 extrusion granulation: the core layer premix, the intermediate layer premix were extruded through a twin-screw extruder granulation, the surface premix was extruded through a single-screw extruder granulation to obtain core particles, intermediate layer particles, surface particles; S3. Imprinting molding: The core layer particles and the middle layer particles are respectively put into a twin-screw extruder, and the surface layer particles are put into a single-screw extruder for heating and melting. The three layers are co-extruded and imprinted to obtain the composite heat-resistant diffusion plate.

9. The process for preparing a composite heat-resistant diffusion plate according to claim 8, characterized in that: In step S2, the temperature of each zone of the twin-screw extruder used to prepare the core layer particles is: 160-180°C in the first zone, 190-200°C in the second zone, 210-220°C in the third zone, and the die head temperature is 215-220°C; The temperatures of each zone of the twin-screw extruder used to prepare the intermediate layer particles are: 240-250°C in the first zone, 260-270°C in the second zone, 260-265°C in the third zone, and 265-270°C in the die head. The temperatures of each zone of the single-screw extruder used to prepare the surface layer particles are: 200-210°C in the first zone, 220-230°C in the second zone, 230-240°C in the third zone, and 225-230°C in the die head.

10. The process for preparing a composite heat-resistant diffusion plate according to claim 8, characterized in that: In step S3, the temperature of each zone of the twin-screw extruder for melting the core layer particles is: 190-200°C in the first zone, 210-220°C in the second zone, and 205-210°C in the die head; The temperature of each zone of the twin-screw extruder used for melting the intermediate layer particles is: 260-270°C in the first zone, 275-280°C in the second zone, and 265-270°C in the die head; The temperatures of each zone of the single-screw extruder used for melting the surface layer particles are: 220-230°C in the first zone, 235-240°C in the second zone, and 235-240°C in the die head.

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