A modified polystyrene material, a method for preparing the same, and a light diffusion plate using the same

Abstract

The application discloses a modified polystyrene material, a preparation method and application of a light diffusion plate, relates to the technical field of light diffusion plate materials, and belongs to the patent publication C08L53 / 02. The preparation method of the modified polystyrene material comprises the following steps: mixing styrene monomers, alpha-methyl styrene monomers, a vinyl-functionalized cage silsesquioxane, benzoyl peroxide and dodecyl mercaptan, performing a polymerization reaction under nitrogen protection to obtain a polystyrene prepolymer; dispersing zirconium phosphate nanosheets in anhydrous ethanol, adding gamma-(methacryloyloxy) propyl trimethoxysilane and glacial acetic acid, and performing a reflux reaction to obtain zirconium phosphate nanosheets modified by a coupling agent; crushing the polystyrene prepolymer, pre-mixing the polystyrene prepolymer with the zirconium phosphate nanosheets modified by the coupling agent, an antioxidant and a lubricant at a high speed, drying the mixture, feeding the mixture into a double-screw extruder for melt blending, extruding, cooling, cutting and drying, and thus obtaining the modified polystyrene material. The prepared modified polystyrene material has excellent heat resistance.

Description

Technical Field

[0001] This invention relates to the field of light diffusion plate material technology, belonging to patent publication number C08L53 / 02, specifically to a modified polystyrene material, preparation method, and application of a light diffusion plate. Background Technology

[0002] As a core optical component in LED lighting, display devices, and other fields, light diffuser plates function primarily to achieve soft light emission and uniform illumination by scattering and homogenizing light. Among the many substrates used to prepare light diffuser plates, polystyrene (PS), especially general-purpose polystyrene, has become one of the most popular and ideal materials in the industry due to its significant advantages such as low density, moderate light transmittance, low raw material cost, and ease of processing and molding.

[0003] However, the inherent heat resistance defects of polystyrene severely limit its application and promotion in light diffusion plates. From a material properties perspective, the carbon-carbon double bonds on the benzene rings in the polystyrene molecule are prone to chemical reactions at high temperatures, resulting in poor thermal stability. Its softening temperature is approximately 80℃, and its heat distortion temperature typically does not exceed 85℃. This characteristic leads to numerous problems for polystyrene light diffusion plates in practical use: in the localized high-temperature environment generated by prolonged operation of LED lights, the plates are prone to softening and warping, not only damaging the structural integrity of the equipment but also causing abnormal light diffusion paths due to morphological changes, leading to uneven illuminance, color shift, and other optical performance degradation issues. Simultaneously, the large coefficient of thermal expansion of polystyrene exacerbates the volume shrinkage differences caused by temperature changes, further worsening the deformation of the plates. Summary of the Invention

[0004] The purpose of this invention is to provide a modified polystyrene material, preparation method, and application of a light diffusion plate to solve the technical problem of poor heat resistance of polystyrene light diffusion plates mentioned in the background art.

[0005] To achieve the above objectives, the present invention provides the following technical solution:

[0006] A method for preparing a modified polystyrene material includes the following steps:

[0007] S1. Styrene monomer, α-methylstyrene monomer, vinyl-functionalized cage-type silsesquioxane, benzoyl peroxide and dodecyl mercaptan are mixed and prepolymerized at 75-80°C under nitrogen protection. The temperature is then raised to 105-110°C to continue the polymerization reaction. After the reaction is completed, the mixture is cooled to obtain polystyrene prepolymer.

[0008] S2. Disperse sheet-like α-zirconium phosphate nanosheets in anhydrous ethanol, add γ-(methacryloyloxy)propyltrimethoxysilane and glacial acetic acid, reflux at 70-80℃, centrifuge, wash and dry after the reaction to obtain coupling agent modified zirconium phosphate nanosheets.

[0009] S3. The polystyrene prepolymer is crushed, and then premixed at high speed with coupling agent-modified zirconium phosphate nanosheets, antioxidants and lubricants. After drying, it is fed into a twin-screw extruder for melt blending, extrusion, cooling, pelletizing and drying to obtain modified polystyrene material.

[0010] This invention improves the heat resistance of polystyrene materials through two synergistic approaches. Firstly, by introducing α-methylstyrene as a rigid comonomer into the polystyrene chain, the significant steric hindrance effect of its α-methyl group significantly increases the internal rotational resistance of the polymer backbone, thereby directly enhancing the rigidity of the molecular chain. This results in the material requiring more energy to transition from a glassy state to a highly elastic state, manifesting as a significant increase in the glass transition temperature. Secondly, by introducing vinyl-functionalized cage-like silsesquioxane (V-POSS) as a nano-hybrid crosslinking agent, multiple vinyl groups on its surface copolymerize with styrene during polymerization, forming a uniformly distributed three-dimensional covalent crosslinked network with rigid inorganic siloxane cages as nodes in situ within the polymer matrix. This network, like a microscopic steel skeleton, greatly restricts the thermal mobility of the polymer molecular chains, making it difficult for chain segments to slip and creep under heat, thus significantly increasing the material's heat distortion temperature.

[0011] On the other hand, KH-570-modified α-zirconium phosphate nanosheets can achieve nanoscale dispersion in the polymer matrix. These dispersed layered nanofillers construct a complex labyrinthine barrier within the matrix, effectively reflecting, scattering, and prolonging the heat propagation path, generating a significant thermal barrier effect (i.e., the labyrinth effect), thereby slowing down the overall heating process of the material. Furthermore, these dispersed rigid nanosheets themselves act as efficient physical crosslinking points, interpenetrating with the aforementioned V-POSS chemical crosslinking network to form a stable dual-network structure, further restricting the movement of polymer chain segments. This further improves the heat resistance of polystyrene materials.

[0012] Preferably, in step S1, the mass ratio of styrene monomer, α-methylstyrene monomer, and vinyl-functionalized cage-like silsesquioxane is 100:5 to 10:3 to 6.

[0013] Preferably, in step S1, the prepolymerization reaction time is 2 to 5 hours.

[0014] Preferably, in step S1, the polymerization reaction time is 3 to 6 hours.

[0015] Preferably, in step S2, the mass ratio of the sheet-like α-zirconium phosphate nanosheets to γ-(methacryloyloxy)propyltrimethoxysilane is 5:0.3 to 0.8.

[0016] Preferably, in step S2, the reflux reaction time is 3 to 6 hours.

[0017] Preferably, in step S3, the coupling agent-modified zirconium phosphate nanosheets undergo a modification treatment, including the following steps:

[0018] Zirconium phosphate nanosheets modified with coupling agent were dispersed in ethanol, and 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid was added. The mixture was heated under reflux and then centrifuged, washed, and dried to obtain modified zirconium phosphate nanosheets.

[0019] In this invention, the team discovered through in-depth research that the coupling agent-modified zirconium phosphate nanosheets have poor compatibility with the polymer matrix. This weak interfacial compatibility leads to numerous microscopic defects and voids. When the material expands under heat, internal thermal stress is generated. The V-POSS crosslinking points, which should be reinforcing points in the polymer matrix, become thermal stress amplifiers due to surrounding rigid defects. Under high temperature and stress, these highly concentrated stresses force the V-POSS crosslinking points to fracture, resulting in a decrease in heat resistance and mechanical strength. To further address this problem, this invention further modifies the coupling agent-modified zirconium phosphate nanosheets. 1-Butyl-3-methylimidazolium hexafluorophosphate forms a stable organic coating layer on the nanosheet surface through strong electrostatic interaction and steric hindrance, significantly improving its interfacial compatibility in the polymer matrix. This effectively eliminates stress concentration caused by interfacial defects, allowing the V-POSS crosslinking network and the nanosheet reinforcing phase to work synergistically, thereby greatly improving the heat resistance and mechanical strength of the composite material.

[0020] Preferably, the mass ratio of the coupling agent-modified zirconium phosphate nanosheets to 1-butyl-3-methylimidazolium hexafluorophosphate is 5:1 to 2.

[0021] A modified polystyrene material is prepared by the method described above.

[0022] A light diffusion plate is prepared from the above-mentioned modified polystyrene material.

[0023] Compared with the prior art, the beneficial effects of the present invention are:

[0024] 1. By introducing α-methylstyrene rigid monomers and V-POSS nano-crosslinking agents into the polystyrene molecular chain, a three-dimensional crosslinking network was constructed at the molecular level, significantly improving the glass transition temperature and heat distortion temperature of the material. Simultaneously, by adding surface-modified zirconium phosphate nanosheets, an effective thermal barrier effect was formed in the matrix, further delaying heat propagation and achieving multi-level synergistic heat resistance modification.

[0025] 2. By modifying the surface of the coupling agent zirconium phosphate nanosheets with ionic liquid, the interfacial compatibility between the nanofiller and the polymer matrix is ​​significantly improved, and the stress concentration problem caused by interfacial defects is eliminated. This strengthened interface enables the V-POSS crosslinking network and the nanosheet reinforcing phase to work synergistically, which not only improves the heat resistance of the material, but also ensures that its mechanical strength does not decrease due to the addition of filler. Attached Figure Description

[0026] Figure 1 This is a SEM image of the modified zirconium phosphate nanosheets prepared in this invention. Detailed Implementation

[0027] The technical solutions in the embodiments of the present invention will be clearly and completely described below. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of them. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0028] Example 1

[0029] A method for preparing a modified polystyrene material includes the following steps:

[0030] Step 1: Under nitrogen protection, add 100g of styrene monomer, 9g of α-methylstyrene monomer, 5g of vinyl-functionalized cage-like silsesquioxane, 0.4g of benzoyl peroxide, and 0.05g of dodecyl mercaptan to a three-necked flask equipped with a stirrer, condenser, and nitrogen inlet tube, and mix thoroughly at 250 rpm. Then, raise the reaction system temperature to 78°C and carry out the prepolymerization reaction at this temperature for 4 hours. Afterward, raise the reaction system temperature to 108°C and continue the polymerization reaction for 5 hours. After the reaction is complete, stop heating and allow the reaction system to cool naturally to room temperature to obtain a viscous polystyrene prepolymer.

[0031] Step 2: Weigh 5.0 g of sheet-like α-zirconium phosphate nanosheets and disperse them in 200 mL of anhydrous ethanol. Sonicate the solution for 1.5 h to obtain a homogeneous suspension. Transfer the suspension to a three-necked flask, then add 0.7 g of γ-(methacryloyloxy)propyltrimethoxysilane and 0.1 mL of glacial acetic acid. Heat the system to 75 °C and reflux at this temperature for 5 h. After the reaction is complete, centrifuge the product and wash it three times with ethanol to remove unreacted substances. Finally, dry the solid product in a vacuum drying oven at 80 °C for 12 h to obtain coupling agent-modified zirconium phosphate nanosheets.

[0032] Step 3: 5.0 g of coupling agent-modified zirconium phosphate nanosheets were dispersed in 150 mL of ethanol, and then 1.8 g of 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid was added. The system was heated to 75 °C and refluxed for 2 h. After the reaction was completed, the solid product was collected by centrifugation, washed three times with ethanol, and finally dried in a vacuum drying oven at 80 °C for 12 h to obtain modified zirconium phosphate nanosheets.

[0033] Polystyrene prepolymer was crushed into particles with a diameter of 3–5 mm using a cryogenic pulverizer. 100 g of polystyrene prepolymer particles, 6.0 g of modified zirconium phosphate nanosheets, 0.3 g of antioxidant 1010, and 0.5 g of calcium stearate lubricant were weighed and placed in a high-speed mixer, mixed at 800 rpm for 5 minutes to ensure uniform premixing of all components. The premix was then dried at 80°C for 2 hours to remove moisture. The dried premix was then fed into a co-rotating twin-screw extruder for melt blending. The extruder temperatures were set as follows: Zone 1 165°C, Zone 2 185°C, Zone 3 200°C, Zone 4 205°C, and the die head 200°C; the screw speed was set to 200 rpm. After melt extrusion, water cooling, and pelletizing, the mixture was dried in an 80°C oven for 4 hours to obtain modified polystyrene material particles.

[0034] Example 2

[0035] A method for preparing a modified polystyrene material includes the following steps:

[0036] Step 1: Under nitrogen protection, add 100g of styrene monomer, 7g of α-methylstyrene monomer, 4g of vinyl-functionalized cage-like silsesquioxane, 0.4g of benzoyl peroxide, and 0.05g of dodecyl mercaptan to a three-necked flask equipped with a stirrer, condenser, and nitrogen inlet tube, and mix thoroughly at 250 rpm. Then, raise the reaction system temperature to 78°C and carry out the prepolymerization reaction at this temperature for 3 hours. Afterward, raise the reaction system temperature to 108°C and continue the polymerization reaction for 4 hours. After the reaction is complete, stop heating and allow the reaction system to cool naturally to room temperature to obtain a viscous polystyrene prepolymer.

[0037] Step 2: Weigh 5.0 g of sheet-like α-zirconium phosphate nanosheets and disperse them in 200 mL of anhydrous ethanol. Sonicate the solution for 1.5 h to obtain a homogeneous suspension. Transfer the suspension to a three-necked flask, then add 0.4 g of γ-(methacryloyloxy)propyltrimethoxysilane and 0.1 mL of glacial acetic acid. Heat the system to 75 °C and reflux at this temperature for 4 h. After the reaction is complete, centrifuge the product and wash it three times with ethanol to remove unreacted substances. Finally, dry the solid product in a vacuum drying oven at 80 °C for 12 h to obtain coupling agent-modified zirconium phosphate nanosheets.

[0038] Step 3: 5.0 g of coupling agent-modified zirconium phosphate nanosheets were dispersed in 150 mL of ethanol, and then 1.2 g of 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid was added. The system was heated to 75 °C and refluxed for 2 h. After the reaction was completed, the solid product was collected by centrifugation, washed three times with ethanol, and finally dried in a vacuum drying oven at 80 °C for 12 h to obtain modified zirconium phosphate nanosheets.

[0039] Polystyrene prepolymer was crushed into particles with a diameter of 3-5 mm using a cryogenic pulverizer. 100 g of polystyrene prepolymer particles, 6.0 g of modified zirconium phosphate nanosheets, 0.3 g of antioxidant 1010, and 0.5 g of calcium stearate lubricant were weighed and placed in a high-speed mixer, mixed at 800 rpm for 5 minutes to ensure uniform premixing of all components. The premix was then dried at 80°C for 2 hours to remove moisture. The dried premix was then fed into a co-rotating twin-screw extruder for melt blending. The extruder temperatures were set as follows: Zone 1 165°C, Zone 2 185°C, Zone 3 200°C, Zone 4 205°C, and the die head 200°C; the screw speed was set to 200 rpm. After melt extrusion, water cooling, and pelletizing, the mixture was dried in an 80°C oven for 4 hours to obtain modified polystyrene material particles.

[0040] Example 3

[0041] A method for preparing a modified polystyrene material includes the following steps:

[0042] Step 1: Under nitrogen protection, add 100g of styrene monomer, 8g of α-methylstyrene monomer, 4.5g of vinyl-functionalized cage-like silsesquioxane, 0.4g of benzoyl peroxide, and 0.05g of dodecyl mercaptan to a three-necked flask equipped with a stirrer, condenser, and nitrogen inlet tube, and mix thoroughly at 250 rpm. Then, raise the reaction system temperature to 78°C and carry out the prepolymerization reaction at this temperature for 3.5 hours. Afterward, raise the reaction system temperature to 108°C and continue the polymerization reaction for 4.5 hours. After the reaction is complete, stop heating and allow the reaction system to cool naturally to room temperature to obtain a viscous polystyrene prepolymer.

[0043] Step 2: Weigh 5.0 g of sheet-like α-zirconium phosphate nanosheets and disperse them in 200 mL of anhydrous ethanol. Sonicate the solution for 1.5 h to obtain a homogeneous suspension. Transfer the suspension to a three-necked flask, then add 0.5 g of γ-(methacryloyloxy)propyltrimethoxysilane and 0.1 mL of glacial acetic acid. Heat the system to 75 °C and reflux at this temperature for 4.5 h. After the reaction is complete, centrifuge the product and wash it three times with ethanol to remove unreacted substances. Finally, dry the solid product in a vacuum drying oven at 80 °C for 12 h to obtain coupling agent-modified zirconium phosphate nanosheets.

[0044] Step 3: 5.0 g of coupling agent-modified zirconium phosphate nanosheets were dispersed in 150 mL of ethanol, and then 1.5 g of 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid was added. The system was heated to 75 °C and refluxed for 2 h. After the reaction was completed, the solid product was collected by centrifugation, washed three times with ethanol, and finally dried in a vacuum drying oven at 80 °C for 12 h to obtain modified zirconium phosphate nanosheets.

[0045] Polystyrene prepolymer was crushed into particles with a diameter of 3-5 mm using a cryogenic pulverizer. 100 g of polystyrene prepolymer particles, 6.0 g of modified zirconium phosphate nanosheets, 0.3 g of antioxidant 1010, and 0.5 g of calcium stearate lubricant were weighed and placed in a high-speed mixer, mixed at 800 rpm for 5 minutes to ensure uniform premixing of all components. The premix was then dried at 80°C for 2 hours to remove moisture. The dried premix was then fed into a co-rotating twin-screw extruder for melt blending. The extruder temperatures were set as follows: Zone 1 165°C, Zone 2 185°C, Zone 3 200°C, Zone 4 205°C, and the die head 200°C; the screw speed was set to 200 rpm. After melt extrusion, water cooling, and pelletizing, the mixture was dried in an 80°C oven for 4 hours to obtain modified polystyrene material particles.

[0046] Example 4

[0047] A method for preparing a modified polystyrene material includes the following steps:

[0048] Step 1: Under nitrogen protection, add 100g of styrene monomer, 10g of α-methylstyrene monomer, 6g of vinyl-functionalized cage-like silsesquioxane, 0.4g of benzoyl peroxide, and 0.05g of dodecyl mercaptan to a three-necked flask equipped with a stirrer, condenser, and nitrogen inlet tube, and mix thoroughly at 250 rpm. Then, raise the reaction system temperature to 80°C and carry out the prepolymerization reaction at this temperature for 5 hours. Afterward, raise the reaction system temperature to 110°C and continue the polymerization reaction for 6 hours. After the reaction is complete, stop heating and allow the reaction system to cool naturally to room temperature to obtain a viscous polystyrene prepolymer.

[0049] Step 2: Weigh 5.0 g of sheet-like α-zirconium phosphate nanosheets and disperse them in 200 mL of anhydrous ethanol. Sonicate the solution for 1.5 h to obtain a homogeneous suspension. Transfer the suspension to a three-necked flask, then add 0.8 g of γ-(methacryloyloxy)propyltrimethoxysilane and 0.1 mL of glacial acetic acid. Heat the system to 80 °C and reflux at this temperature for 6 h. After the reaction is complete, centrifuge the product and wash it three times with ethanol to remove unreacted substances. Finally, dry the solid product in a vacuum drying oven at 80 °C for 12 h to obtain coupling agent-modified zirconium phosphate nanosheets.

[0050] Step 3: 5.0 g of coupling agent-modified zirconium phosphate nanosheets were dispersed in 150 mL of ethanol, and then 2 g of 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid was added. The system was heated to 75 °C and refluxed for 2 h. After the reaction was completed, the solid product was collected by centrifugation, washed three times with ethanol, and finally dried in a vacuum drying oven at 80 °C for 12 h to obtain modified zirconium phosphate nanosheets.

[0051] Polystyrene prepolymer was crushed into particles with a diameter of 3-5 mm using a cryogenic pulverizer. 100 g of polystyrene prepolymer particles, 6.0 g of modified zirconium phosphate nanosheets, 0.3 g of antioxidant 1010, and 0.5 g of calcium stearate lubricant were weighed and placed in a high-speed mixer, mixed at 800 rpm for 5 minutes to ensure uniform premixing of all components. The premix was then dried at 80°C for 2 hours to remove moisture. The dried premix was then fed into a co-rotating twin-screw extruder for melt blending. The extruder temperatures were set as follows: Zone 1 165°C, Zone 2 185°C, Zone 3 200°C, Zone 4 205°C, and the die head 200°C; the screw speed was set to 200 rpm. After melt extrusion, water cooling, and pelletizing, the mixture was dried in an 80°C oven for 4 hours to obtain modified polystyrene material particles.

[0052] Example 5

[0053] A method for preparing a modified polystyrene material includes the following steps:

[0054] Step 1: Under nitrogen protection, add 100g of styrene monomer, 5g of α-methylstyrene monomer, 3g of vinyl-functionalized cage-like silsesquioxane, 0.4g of benzoyl peroxide, and 0.05g of dodecyl mercaptan to a three-necked flask equipped with a stirrer, condenser, and nitrogen inlet tube, and mix thoroughly at 250 rpm. Then, raise the reaction system temperature to 75°C and carry out the prepolymerization reaction at this temperature for 2 hours. Afterward, raise the reaction system temperature to 105°C and continue the polymerization reaction for 3 hours. After the reaction is complete, stop heating and allow the reaction system to cool naturally to room temperature to obtain a viscous polystyrene prepolymer.

[0055] Step 2: Weigh 5.0 g of sheet-like α-zirconium phosphate nanosheets and disperse them in 200 mL of anhydrous ethanol. Sonicate the solution for 1.5 h to obtain a homogeneous suspension. Transfer the suspension to a three-necked flask, then add 0.3 g of γ-(methacryloyloxy)propyltrimethoxysilane and 0.1 mL of glacial acetic acid. Heat the system to 70 °C and reflux at this temperature for 3 h. After the reaction is complete, centrifuge the product and wash it three times with ethanol to remove unreacted substances. Finally, dry the solid product in a vacuum drying oven at 80 °C for 12 h to obtain coupling agent-modified zirconium phosphate nanosheets.

[0056] Step 3: 5.0 g of coupling agent-modified zirconium phosphate nanosheets were dispersed in 150 mL of ethanol, and then 1 g of 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid was added. The system was heated to 75 °C and refluxed for 2 h. After the reaction was completed, the solid product was collected by centrifugation, washed three times with ethanol, and finally dried in a vacuum drying oven at 80 °C for 12 h to obtain modified zirconium phosphate nanosheets.

[0057] Polystyrene prepolymer was crushed into particles with a diameter of 3–5 mm using a cryogenic pulverizer. 100 g of polystyrene prepolymer particles, 6.0 g of modified zirconium phosphate nanosheets, 0.3 g of antioxidant 1010, and 0.5 g of calcium stearate lubricant were weighed and placed in a high-speed mixer, mixed at 800 rpm for 5 minutes to ensure uniform premixing of all components. The premix was then dried at 80°C for 2 hours to remove moisture. The dried premix was then fed into a co-rotating twin-screw extruder for melt blending. The extruder temperatures were set as follows: Zone 1 165°C, Zone 2 185°C, Zone 3 200°C, Zone 4 205°C, and the die head 200°C; the screw speed was set to 200 rpm. After melt extrusion, water cooling, and pelletizing, the mixture was dried in an 80°C oven for 4 hours to obtain modified polystyrene material particles.

[0058] Comparative Example 1: The difference between Comparative Example 1 and Example 1 is that the modified polystyrene material is replaced with ordinary polystyrene material.

[0059] Comparative Example 2: The difference between Comparative Example 1 and Example 1 is that α-methylstyrene monomer and vinyl-functionalized cage-like silsesquioxane are not added in step 1 of the preparation process of the modified polystyrene material.

[0060] Comparative Example 3: The difference between Comparative Example 3 and Example 1 is that modified zirconium phosphate nanosheets are not added in step 3 of the preparation process of the modified polystyrene material.

[0061] Comparative Example 4: The difference between Comparative Example 4 and Example 1 is that the modified zirconium phosphate nanosheets in step 3 are replaced with ordinary zirconium phosphate nanosheets in the preparation process of the modified polystyrene material.

[0062] Comparative Example 5: The difference between Comparative Example 5 and Example 1 is that the coupling agent-modified zirconium phosphate nanosheets in step 3 of the preparation process of the modified polystyrene material are not modified, that is, the modified zirconium phosphate nanosheets are replaced with coupling agent-modified zirconium phosphate nanosheets.

[0063] Performance testing:

[0064] 1. Glass transition temperature (Tg) test: The test was performed according to GB / T 19466.2-2004 "Differential Scanning Calorimetry (DSC) for Plastics - Part 2: Determination of Glass Transition Temperature". 10 mg of dried modified polystyrene particles were placed in an aluminum sample cell. Nitrogen gas was used as the protective gas (flow rate 50 mL / min), and the test was conducted using a differential scanning calorimeter (DSC). The heating rate was set to 10 °C / min, and the test temperature range was 30–150 °C. The midpoint temperature of the glass transition stage in the DSC curve was recorded as the Tg value of the material. Three parallel tests were performed, and the average value was taken. The test results are shown in Table 1.

[0065] 2. Heat distortion temperature test: The test was conducted according to GB / T 1634.2-2004 "Determination of load distortion temperature of plastics - Part 2: Plastics, hard rubber and long fiber reinforced composites". Modified polystyrene material was injection molded into standard specimens. A heat distortion temperature tester was used, with a static bending load of 1.82 MPa and a heating rate of 120℃ / h. The temperature at which the deformation at the midpoint of the specimen reached 0.25 mm was taken as the heat distortion temperature. Three specimens were tested in each group, and the average value was taken. The test results are shown in Table 1.

[0066] 3. Tensile Strength Test: The test was conducted according to GB / T 1040.2-2006 "Determination of Tensile Properties of Plastics - Part 2: Test Conditions for Molded and Extruded Plastics". The material was injection molded into Type I standard tensile specimens. The test was performed using a universal testing machine with a tensile speed set to 50 mm / min. The maximum load and elongation at fracture were recorded. The tensile strength was calculated using the formula: Tensile Strength = Maximum Load / Original Cross-sectional Area of ​​Specimen. Five parallel tests were performed, and the average value was taken. The test results are shown in Table 1.

[0067] 4. Transmittance Test: The test was conducted according to GB / T 2410-2008, "Determination of Transmittance and Haze of Transparent Plastics". A light diffusion plate sample (50mm diameter, surface free of scratches) with a thickness of 3mm was prepared from modified polystyrene material. A transmittance meter was used for testing, with standard white light as the light source. First, the transmittance of the blank sample (air) was tested, then the transmittance of the sample (total transmittance) was tested. Three samples were tested in each group, and the average value was taken. The test results are shown in Table 1.

[0068] Table 1:

[0069]

[0070] Although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the protection scope of the present invention.

Claims

1. A method for preparing a modified polystyrene material, characterized in that, Includes the following steps: S1. Styrene monomer, α-methylstyrene monomer, vinyl-functionalized cage-like silsesquioxane, benzoyl peroxide and dodecyl mercaptan are mixed, wherein the mass ratio of styrene monomer, α-methylstyrene monomer and vinyl-functionalized cage-like silsesquioxane is 100:5~10:3~6. Under nitrogen protection, a prepolymerization reaction is first carried out at 75~80℃, and then the temperature is raised to 105~110℃ to continue the polymerization reaction. After the reaction is completed, the mixture is cooled to obtain polystyrene prepolymer. S2. Disperse sheet-like α-zirconium phosphate nanosheets in anhydrous ethanol, add γ-(methacryloyloxy)propyltrimethoxysilane and glacial acetic acid, the mass ratio of sheet-like α-zirconium phosphate nanosheets to γ-(methacryloyloxy)propyltrimethoxysilane is 5:0.3-0.8, reflux reaction at 70-80℃, after the reaction is completed, centrifuge, wash and dry to obtain coupling agent modified zirconium phosphate nanosheets; S3. The polystyrene prepolymer is crushed, and then premixed at high speed with coupling agent-modified zirconium phosphate nanosheets, antioxidants and lubricants. After drying, it is fed into a twin-screw extruder for melt blending, extrusion, cooling, pelletizing and drying to obtain modified polystyrene material.

2. The method for preparing a modified polystyrene material according to claim 1, characterized in that, In step S1, the prepolymerization reaction time is 2 to 5 hours.

3. The method for preparing a modified polystyrene material according to claim 1, characterized in that, In step S1, the polymerization reaction time is 3 to 6 hours.

4. The method for preparing a modified polystyrene material according to claim 1, characterized in that, In step S2, the reflux reaction time is 3 to 6 hours.

5. The method for preparing a modified polystyrene material according to claim 1, characterized in that, In step S3, the coupling agent-modified zirconium phosphate nanosheets undergo a modification treatment, including the following steps: Zirconium phosphate nanosheets modified with coupling agent were dispersed in ethanol, and 1-butyl-3-methylimidazolium hexafluorophosphate ionic liquid was added. The mixture was heated under reflux and then centrifuged, washed, and dried to obtain modified zirconium phosphate nanosheets.

6. The method for preparing a modified polystyrene material according to claim 5, characterized in that, The mass ratio of the coupling agent-modified zirconium phosphate nanosheets to 1-butyl-3-methylimidazolium hexafluorophosphate is 5:1 to 2.

7. A modified polystyrene material, characterized in that, It is prepared by the method described in any one of claims 1-6.

8. A light diffusion plate, characterized in that, It is prepared from the modified polystyrene material according to claim 7.

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