Optical-grade polymethyl methacrylate material and preparation method thereof

Abstract

The invention relates to the technical field of polymer optical materials, in particular to an optical-grade polymethyl methacrylate material and a preparation method thereof, and the optical-grade polymethyl methacrylate material comprises the following raw materials in parts by weight: 95-105 parts of methyl methacrylate, 200-240 parts of a composite liquid medium, 1.5-2.5 parts of a composite additive and 0.08-0.12 part of an initiator. According to the invention, the composite additive is used as a main material and the composite liquid medium is used as an auxiliary material, so that the heat resistance and the size stability of the material are synergistically improved, powder in the composite additive is uniformly dispersed in a methyl methacrylate matrix to form a compact physical support skeleton, and the powder is matched with a treating agent and a methyl methacrylate molecular chain to form strong chemical bond combination; the composite liquid medium optimizes the flowability of a polymerization system, reduces polymerization internal stress residues, avoids material deformation caused by internal stress release at high temperature, and enhances high-temperature stability.

Description

Technical Field

[0001] This invention relates to the field of polymer optical materials technology, specifically to an optical-grade polymethyl methacrylate material and its preparation method. Background Technology

[0002] Optical grade polymethyl methacrylate, commonly known as optical acrylic, is one of the most widely used transparent engineering plastics. It has core advantages such as high visible light transmittance, stable refractive index, excellent processing performance, and moderate cost, making it irreplaceable in fields such as consumer electronics, optical instruments, automotive optics, and medical testing.

[0003] In the prior art, such as Chinese Patent No. CN107964200A, a modified polymethyl methacrylate (PMMA) material and its preparation method are disclosed. This material exhibits good strength properties; however, the simple molecular chain structure of PMMA lacks effective support, resulting in poor heat resistance, low heat distortion temperature, and susceptibility to deformation at high temperatures, thus limiting its applicability. Therefore, this invention provides an optical-grade PMMA material and its preparation method. Summary of the Invention

[0004] The purpose of this invention is to provide an optical-grade polymethyl methacrylate (PMMA) material and its preparation method. The optical-grade PMMA material prepared by this invention not only has good heat resistance but also excellent optical properties, effectively improving the performance of optical-grade PMMA materials.

[0005] To achieve the above objectives, the present invention provides the following technical solution: In a first aspect, the present invention provides an optical grade polymethyl methacrylate material comprising the following parts by weight of raw materials: 95-105 parts of methyl methacrylate, 200-240 parts of composite liquid medium, 1.5-2.5 parts of composite additives, and 0.08-0.12 parts of initiator.

[0006] Furthermore, the composite liquid medium comprises semiconductor nanocrystals and ionic liquids. Furthermore, the composite additive includes additives and treatment agents.

[0007] Furthermore, the methyl methacrylate is pretreated before preparing optical-grade polymethyl methacrylate materials.

[0008] Furthermore, the preparation method of the composite liquid medium is as follows: the ionic liquid is preheated to 40°C in a water bath, semiconductor nanocrystals are added, and the mixture is first ultrasonically treated at a frequency of 40kHz and a power of 200-300W for 10-15 minutes, and then magnetically stirred at 200-300rpm for 0.5-1.5 hours to obtain the composite liquid medium, wherein the mass of the semiconductor nanocrystals is 0.2-0.4% of the mass of the ionic liquid.

[0009] Furthermore, the semiconductor nanocrystals are a mixture of cesium lead bromide perovskite quantum dots and copper indium sulfide quantum dots in a molar ratio of 1:(1-2).

[0010] Furthermore, the ionic liquid is 1-butyl-3-methylimidazolium tetrafluoroborate with a water content of less than 30 ppm.

[0011] Further, the preparation method of the composite additive is as follows: the additive and the treatment agent are mixed at a mass ratio of (0.3-0.5):(1-2) to obtain a mixture. 5-10% of 3A molecular sieve by mass is added to the mixture, and it is dried at 20-25℃ for 12h, and then vacuum dried at 55-65℃ for 12h. PEG-6000 is added to the dried mixture, and it is stirred at 70℃ and 3000-4000rpm for 20-30min to obtain the composite additive. The 3A molecular sieve is first activated in a muffle furnace at 300℃ for 2h. The pore size of the 3A molecular sieve is 0.3nm, and the mass of PEG-6000 is 8-12% of the mixture.

[0012] Further, the preparation method of the additive is as follows: polystyrene microspheres are dispersed in anhydrous ethanol at a solid-liquid ratio of 1:(10-20), and the mixture is magnetically stirred at 200-300 rpm for 30 min at 20-30°C to obtain a dispersion. Tetraethyl orthosilicate and ammonia water with a mass fraction of 25-30% are added to the dispersion, and the mixture is stirred at 20-30°C for 6 h. After the reaction is completed, the mixture is centrifuged at 4000-5000 rpm for 10-15 min, and the product is collected. The product is washed with anhydrous ethanol until neutral, and then placed in a low-temperature plasma treatment instrument with argon as the carrier gas, a flow rate of 50 sccm, and a power of 100 W for 5-10 min to obtain the additive. The particle size of the polystyrene microspheres is 2 μm, the mass of tetraethyl orthosilicate is 20-30% of the mass of the polystyrene microspheres, and the volume of ammonia water is 1-2% of the volume of the dispersion.

[0013] Further, the preparation method of the treatment agent is as follows: hydroxyadamantyl acrylate and methyl acrylate are mixed at a molar ratio of 1:(18-20), azobisisobutyronitrile is added, and the mixture is reacted at 55-65℃ for 3-5 hours under a nitrogen atmosphere. After the reaction is completed, the mixture is centrifuged at 4000-5000 rpm for 5-15 minutes. The precipitate collected by centrifugation is washed with anhydrous methanol until neutral, and then dried under vacuum at 40-50℃ and 10-30 mmHg for 24 hours. The dried product is dissolved in toluene at a solid-liquid ratio of 1:(5-10), maleic anhydride is added, and the mixture is refluxed at 75-85℃ for 2 hours to obtain the treatment agent. The mass of azobisisobutyronitrile is 0.1% of the total mass of hydroxyadamantyl acrylate and methyl acrylate, and the mass of maleic anhydride is 1-3% of the mass of the dried product.

[0014] Further, the pretreatment method for methyl methacrylate is as follows: methyl methacrylate is first extracted for 30 min at 35-45℃, 20-30 MPa, and a CO2 flow rate of 10 L / min using a supercritical CO2 extraction device with 5 wt% ethanol as the entrainer. Then, it is treated for 1-2 h at 20-25℃ and atmospheric pressure using a molecularly imprinted polymer column synthesized with hydroquinone as the template molecule. Finally, it is dried for 48 h at 20-25℃ using 5-10% 3A molecular sieve by mass of methyl methacrylate. The 3A molecular sieve is first activated in a muffle furnace at 300℃ for 2 h. The pore size of the 3A molecular sieve is 0.3 nm. The length of the molecularly imprinted polymer column is 20-30 cm, the inner diameter is 1-2 cm, and the particle size of the particles packed in the column is 0.1-0.3 mm.

[0015] Furthermore, the initiator is benzoyl peroxide with a purity ≥99% and a moisture content ≤0.1%.

[0016] Secondly, the present invention provides a method for preparing optical-grade polymethyl methacrylate material, comprising the following steps: S1: Construction of the polymerization system: Methyl methacrylate is added to the composite liquid medium and stirred at 200-300 rpm for 30 min. Then, composite additives and initiators are added and stirred at 3000 rpm for 20 min to obtain a mixture. S2: The mixture is injected into a 2mm thick mold, sealed with polytetrafluoroethylene, prepolymerized at 35-45℃ for 1h, and then polymerized at 70-80℃ for 4-5h at a rate of 5-10℃ / h to obtain an intermediate product. Anhydrous ethanol is added to the intermediate product at a volume ratio of 1:(2-3) at 20-25℃, stirred at 200-300rpm for 30min, allowed to stand for 1h, and then centrifuged at 4000-5000rpm for 10min to obtain the crude product. S3: The crude product is dried in a vacuum drying oven at 55-65℃ and a vacuum degree of 10-30 mmHg for 24 hours to obtain optical grade polymethyl methacrylate material.

[0017] Compared with the prior art, the beneficial effects of the present invention are: 1. In this invention, composite additives are used as the main component and composite liquid media are used as an auxiliary component to synergistically improve the heat resistance and dimensional stability of the material. The powder in the composite additives is uniformly dispersed in the methyl methacrylate matrix to form a dense physical support skeleton. Combined with the treatment agent, it forms a strong chemical bond with the methyl methacrylate molecular chain, which effectively restricts the slippage of the molecular chain at high temperature and increases the heat distortion temperature of the material. The composite liquid media optimizes the fluidity of the polymerization system, reduces the residual internal stress of polymerization, avoids the release of internal stress at high temperature that leads to material deformation, and enhances high temperature stability.

[0018] 2. In this invention, the optical performance of the material is improved by using a composite liquid medium to assist dispersion and a composite additive to optimize the interface. The composite liquid medium uses an ionic liquid as a carrier and is combined with an ultrasonic dispersion process to uniformly disperse the composite semiconductor nanocrystals, blocking the agglomeration of quantum dots and reducing the risk of light scattering caused by agglomeration from the source. The treatment agent in the composite additive, combined with plasma-modified additives, further optimizes the interfacial compatibility of the system. Combined with high-purity pretreated monomers, the haze of the material is reduced and the visible light transmittance is improved, reducing the defects of excessive haze and low transmittance of conventional optical polymethyl methacrylate materials. Attached Figure Description

[0019] Figure 1 The present invention provides a flowchart of an optical-grade polymethyl methacrylate material and its preparation method. Detailed Implementation

[0020] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. 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.

[0021] It should be noted that the raw materials used in the following embodiments are all commercially available.

[0022] Example 1:

[0023] Prepare the following raw materials by weight: 95 parts methyl methacrylate, 200 parts composite liquid medium, 1.5 parts composite additive and 0.08 parts initiator, wherein the initiator is benzoyl peroxide.

[0024] Pretreatment of methyl methacrylate: Methyl methacrylate was first extracted for 30 min at 35 °C, 20 MPa and CO2 flow rate of 10 L / min using a supercritical CO2 extraction device with 5 wt% ethanol as the entrainer. Then it was passed through a molecularly imprinted polymer column synthesized with hydroquinone as the template molecule and treated for 1 h at 20 °C and atmospheric pressure with a flow rate of 1 mL / min. Finally, it was dried at 20 °C for 48 h with 5% 3A molecular sieve by mass of methyl methacrylate. The 3A molecular sieve was first activated in a muffle furnace at 300 °C for 2 h. The pore size of the 3A molecular sieve was 0.3 nm. The length of the molecularly imprinted polymer column was 20 cm and the inner diameter was 1 cm. The particles packed in the column had a particle size of 0.1 mm.

[0025] Preparation of composite liquid medium: The ionic liquid was preheated to 40℃ in a water bath, semiconductor nanocrystals were added, and the mixture was first ultrasonically treated at a frequency of 40kHz and a power of 200W for 10min, and then magnetically stirred at 200rpm for 0.5h to obtain the composite liquid medium. The mass of the semiconductor nanocrystals was 0.2% of the mass of the ionic liquid. The semiconductor nanocrystals were a mixture of cesium lead bromide perovskite quantum dots and copper indium sulfide quantum dots in a molar ratio of 1:1. The ionic liquid was 1-butyl-3-methylimidazolium tetrafluoroborate with a water content of less than 30ppm.

[0026] Preparation of additive: Polystyrene microspheres were dispersed in anhydrous ethanol at a solid-liquid ratio of 1:10 and stirred magnetically at 200 rpm for 30 min at 20 °C to obtain a dispersion. Tetraethyl orthosilicate and 25% ammonia water were added to the dispersion and stirred at 20 °C for 6 h. After the reaction was completed, the product was collected by centrifugation at 4000 rpm for 10 min. The product was washed with anhydrous ethanol until neutral and then placed in a low-temperature plasma treatment instrument. Argon gas was used as the carrier gas, with a flow rate of 50 sccm and a power of 100 W for 5 min to obtain the additive. The particle size of the polystyrene microspheres was 2 μm, the mass of tetraethyl orthosilicate was 20% of the mass of the polystyrene microspheres, and the volume of ammonia water was 1% of the volume of the dispersion.

[0027] Preparation of the treatment agent: Hydroxyadamantyl acrylate and methyl acrylate were mixed at a molar ratio of 1:18, and azobisisobutyronitrile was added. The mixture was reacted at 55°C for 3 hours under a nitrogen atmosphere. After the reaction was completed, the mixture was centrifuged at 4000 rpm for 5 minutes. The precipitate collected by centrifugation was washed with anhydrous methanol until neutral and dried under vacuum at 40°C and 10 mmHg for 24 hours. The dried product was dissolved in toluene at a solid-liquid ratio of 1:5, and maleic anhydride was added. The mixture was refluxed at 75°C for 2 hours to obtain the treatment agent. The mass of azobisisobutyronitrile was 0.1% of the total mass of hydroxyadamantyl acrylate and methyl acrylate, and the mass of maleic anhydride was 1% of the mass of the dried product.

[0028] Preparation of composite additive: The additive and the treatment agent were mixed at a mass ratio of 0.3:2 to obtain a mixture. 5% of 3A molecular sieve by mass was added to the mixture, and the mixture was dried at 20℃ for 12h, and then vacuum dried at 55℃ for 12h. PEG-6000 was added to the dried mixture, and the mixture was stirred at 70℃ and 3000rpm for 20min to obtain the composite additive. The 3A molecular sieve was first activated in a muffle furnace at 300℃ for 2h. The pore size of the 3A molecular sieve is 0.3nm. The mass of PEG-6000 is 8% of the mixture.

[0029] Preparation of optical-grade polymethyl methacrylate materials: S1: Construction of the polymerization system: Methyl methacrylate was added to the composite liquid medium and stirred at 200 rpm for 30 min. Then, composite additives and initiators were added and stirred at 3000 rpm for 20 min to obtain a mixture. S2: The mixture was injected into a 2mm thick mold, sealed with polytetrafluoroethylene, prepolymerized at 35℃ for 1h, and then polymerized at 70℃ for 4h at a rate of 5℃ / h to obtain an intermediate product. Anhydrous ethanol was added to the intermediate product at a volume ratio of 1:2 at 20℃, stirred at 200rpm for 30min, allowed to stand for 1h, and then centrifuged at 4000rpm for 10min to obtain the crude product. S3: The crude product was dried in a vacuum drying oven at 55°C and 10 mmHg for 24 hours to obtain optical grade polymethyl methacrylate material.

[0030] Example 2:

[0031] Prepare the following raw materials by weight: 100 parts methyl methacrylate, 220 parts composite liquid medium, 2 parts composite additives and 0.1 parts initiator, wherein the initiator is benzoyl peroxide.

[0032] Pretreatment of methyl methacrylate: Methyl methacrylate was first extracted for 30 min at 40℃, 25 MPa and CO2 flow rate of 10 L / min using a supercritical CO2 extraction device with 5 wt% ethanol as the entrainer. Then it was treated for 1.5 h at 22℃ and atmospheric pressure with a flow rate of 1 mL / min using a molecularly imprinted polymer column synthesized with hydroquinone as the template molecule. Finally, it was dried at 22℃ for 48 h with 3A molecular sieve accounting for 8% of the mass of methyl methacrylate. The 3A molecular sieve was first activated in a muffle furnace at 300℃ for 2 h. The pore size of the 3A molecular sieve is 0.3 nm. The length of the molecularly imprinted polymer column is 25 cm and the inner diameter is 1.5 cm. The particle size of the particles packed in the column is 0.2 mm.

[0033] Preparation of composite liquid medium: The ionic liquid was preheated to 40℃ in a water bath, semiconductor nanocrystals were added, and the mixture was first ultrasonically treated at a frequency of 40kHz and a power of 250W for 12min, and then magnetically stirred at 250rpm for 1h to obtain the composite liquid medium. The mass of the semiconductor nanocrystals was 0.3% of the mass of the ionic liquid. The semiconductor nanocrystals were a mixture of cesium lead bromide perovskite quantum dots and copper indium sulfide quantum dots in a molar ratio of 1:1.5. The ionic liquid was 1-butyl-3-methylimidazolium tetrafluoroborate with a water content of less than 30ppm.

[0034] Preparation of the additive: Polystyrene microspheres were dispersed in anhydrous ethanol at a solid-liquid ratio of 1:15 and stirred magnetically at 250 rpm for 30 min to obtain a dispersion. Tetraethyl orthosilicate and 28% ammonia water were added to the dispersion and stirred at 25°C for 6 h. After the reaction was completed, the product was collected by centrifugation at 4500 rpm for 12 min. The product was washed with anhydrous ethanol until neutral and then placed in a low-temperature plasma treatment instrument. Argon was used as the carrier gas, with a flow rate of 50 sccm and a power of 100 W for 8 min to obtain the additive. The particle size of the polystyrene microspheres was 2 μm, the mass of tetraethyl orthosilicate was 25% of the mass of the polystyrene microspheres, and the volume of ammonia water was 1.5% of the volume of the dispersion.

[0035] Preparation of the treatment agent: Hydroxyadamantyl acrylate and methyl acrylate were mixed at a molar ratio of 1:19, and azobisisobutyronitrile was added. The mixture was reacted at 60°C for 4 hours under a nitrogen atmosphere. After the reaction was completed, the mixture was centrifuged at 4500 rpm for 10 minutes. The precipitate collected by centrifugation was washed with anhydrous methanol until neutral and dried under vacuum at 45°C and 20 mmHg for 24 hours. The dried product was dissolved in toluene at a solid-liquid ratio of 1:8, and maleic anhydride was added. The mixture was refluxed at 80°C for 2 hours to obtain the treatment agent. The mass of azobisisobutyronitrile was 0.1% of the total mass of hydroxyadamantyl acrylate and methyl acrylate, and the mass of maleic anhydride was 2% of the mass of the dried product.

[0036] Preparation of composite additive: The additive and the treatment agent were mixed at a mass ratio of 0.4:1.5 to obtain a mixture. 7.5% of 3A molecular sieve by mass was added to the mixture, and the mixture was dried at 22℃ for 12h, and then vacuum dried at 60℃ for 12h. PEG-6000 was added to the dried mixture, and the mixture was stirred at 70℃ and 3500rpm for 25min to obtain the composite additive. The 3A molecular sieve was first activated in a muffle furnace at 300℃ for 2h. The pore size of the 3A molecular sieve is 0.3nm. The mass of PEG-6000 is 10% of the mixture.

[0037] Preparation of optical-grade polymethyl methacrylate materials: S1: Construction of the polymerization system: Methyl methacrylate was added to the composite liquid medium and stirred at 250 rpm for 30 min. Then, composite additives and initiators were added and stirred at 3000 rpm for 20 min to obtain a mixture. S2: The mixture was injected into a 2mm thick mold, sealed with polytetrafluoroethylene, prepolymerized at 40℃ for 1h, and then heated to 75℃ at a rate of 8℃ / h for 4.5h to obtain an intermediate product. Anhydrous ethanol was added to the intermediate product at a volume ratio of 1:2.5 at 22℃, stirred at 250rpm for 30min, allowed to stand for 1h, and then centrifuged at 4500rpm for 10min to obtain the crude product. S3: The crude product was dried in a vacuum drying oven at 60°C and 20 mmHg for 24 hours to obtain optical grade polymethyl methacrylate material.

[0038] Example 3:

[0039] Prepare the following raw materials by weight: 105 parts methyl methacrylate, 240 parts composite liquid medium, 2.5 parts composite additives and 0.12 parts initiator, wherein the initiator is benzoyl peroxide.

[0040] Pretreatment of methyl methacrylate: Methyl methacrylate was first extracted for 30 min at 45℃, 30 MPa and CO2 flow rate of 10 L / min using a supercritical CO2 extraction device with 5 wt% ethanol as the entrainer. Then it was treated for 2 h at 25℃ and atmospheric pressure with a flow rate of 1 mL / min using a molecularly imprinted polymer column synthesized with hydroquinone as the template molecule. Finally, it was dried at 25℃ for 48 h with 10% 3A molecular sieve by mass of methyl methacrylate. The 3A molecular sieve was first activated in a muffle furnace at 300℃ for 2 h. The pore size of the 3A molecular sieve was 0.3 nm. The length of the molecularly imprinted polymer column was 30 cm and the inner diameter was 2 cm. The particles packed in the column had a particle size of 0.3 mm.

[0041] Preparation of composite liquid medium: The ionic liquid was preheated to 40℃ in a water bath, semiconductor nanocrystals were added, and the mixture was first ultrasonically treated at a frequency of 40kHz and a power of 300W for 15min, and then magnetically stirred at 300rpm for 1.5h to obtain the composite liquid medium. The mass of the semiconductor nanocrystals was 0.4% of the mass of the ionic liquid. The semiconductor nanocrystals were a mixture of cesium lead bromide perovskite quantum dots and copper indium sulfide quantum dots in a molar ratio of 1:2. The ionic liquid was 1-butyl-3-methylimidazolium tetrafluoroborate with a water content of less than 30ppm.

[0042] Preparation of the additive: Polystyrene microspheres were dispersed in anhydrous ethanol at a solid-liquid ratio of 1:20 and stirred magnetically at 300 rpm for 30 min to obtain a dispersion. Tetraethyl orthosilicate and 30% ammonia water were added to the dispersion and stirred at 30°C for 6 h. After the reaction was completed, the product was collected by centrifugation at 5000 rpm for 15 min. The product was washed with anhydrous ethanol until neutral and then placed in a low-temperature plasma treatment instrument. Argon was used as the carrier gas, with a flow rate of 50 sccm and a power of 100 W for 10 min to obtain the additive. The particle size of the polystyrene microspheres was 2 μm, the mass of tetraethyl orthosilicate was 30% of the mass of the polystyrene microspheres, and the volume of ammonia water was 2% of the volume of the dispersion.

[0043] Preparation of the treatment agent: Hydroxyadamantyl acrylate and methyl acrylate were mixed at a molar ratio of 1:20, and azobisisobutyronitrile was added. The mixture was reacted at 65°C for 5 h under a nitrogen atmosphere. After the reaction was completed, the mixture was centrifuged at 5000 rpm for 15 min. The precipitate collected by centrifugation was washed with anhydrous methanol until neutral, and dried under vacuum at 50°C and 30 mmHg for 24 h. The dried product was dissolved in toluene at a solid-liquid ratio of 1:10, and maleic anhydride was added. The mixture was refluxed at 85°C for 2 h to obtain the treatment agent. The mass of azobisisobutyronitrile was 0.1% of the total mass of hydroxyadamantyl acrylate and methyl acrylate, and the mass of maleic anhydride was 3% of the mass of the dried product.

[0044] Preparation of composite additive: The additive and the treatment agent were mixed at a mass ratio of 0.5:1 to obtain a mixture. 10% of the mass of 3A molecular sieve was added to the mixture, and the mixture was dried at 25℃ for 12h, and then vacuum dried at 65℃ for 12h. PEG-6000 was added to the dried mixture, and the mixture was stirred at 70℃ and 4000rpm for 30min to obtain the composite additive. The 3A molecular sieve was first activated in a muffle furnace at 300℃ for 2h. The pore size of the 3A molecular sieve is 0.3nm. The mass of PEG-6000 is 12% of the mixture.

[0045] Preparation of optical-grade polymethyl methacrylate materials: S1: Construction of the polymerization system: Methyl methacrylate was added to the composite liquid medium and stirred at 300 rpm for 30 min. Then, composite additives and initiators were added and stirred at 3000 rpm for 20 min to obtain a mixture. S2: The mixture was injected into a 2mm thick mold, sealed with polytetrafluoroethylene, prepolymerized at 45℃ for 1h, and then polymerized at 80℃ for 5h at a rate of 10℃ / h to obtain an intermediate product. Anhydrous ethanol was added to the intermediate product at a volume ratio of 1:3 at 25℃, stirred at 300rpm for 30min, allowed to stand for 1h, and then centrifuged at 5000rpm for 10min to obtain the crude product. S3: The crude product was dried in a vacuum drying oven at 65°C and 30 mmHg for 24 hours to obtain optical-grade polymethyl methacrylate material.

[0046] Comparative Example 1: The difference between this comparative example and Example 1 is that this comparative example does not contain composite additives.

[0047] Comparative Example 2 differs from Example 1 in that the composite liquid medium in this comparative example is replaced with an equal amount of deionized water.

[0048] Comparative Example 3 differs from Example 1 in that no treatment agent is added during the preparation of the composite additive.

[0049] Performance testing: The optical-grade polymethyl methacrylate materials prepared in Examples 1-3 and Comparative Examples 1-3 were subjected to performance testing, and the test data are recorded in the table below: Table 1

[0050] In the performance test, the heat resistance test was conducted in accordance with ASTM D648, with a load of 1.82 MPa applied, and the heat distortion temperature was tested. Optical performance testing was conducted in accordance with GB / T 2410-2008, testing the transmittance and haze of optical grade polymethyl methacrylate materials. The test environment was: temperature 25℃ and relative humidity 50%.

[0051] The heat distortion temperature test results of the optical grade polymethyl methacrylate materials prepared in Examples 1-3 and Comparative Examples 1-3 were 102℃, 105℃, 103℃, 82℃, 88℃, and 91℃, respectively.

[0052] The transmittance test results of the optical grade polymethyl methacrylate materials prepared in Examples 1-3 and Comparative Examples 1-3 were 93.6%, 93.8%, 93.7%, 85.4%, 88.2%, and 90.1%, respectively.

[0053] The haze test results of the optical grade polymethyl methacrylate materials prepared in Examples 1-3 and Comparative Examples 1-3 were 0.15%, 0.13%, 0.14%, 0.68%, 0.34%, and 0.23%, respectively.

[0054] It is evident that the heat resistance and optical properties of the optical-grade polymethyl methacrylate materials prepared in Comparative Examples 1-3 are lower than those in Examples 1-3. This indicates that in this invention, the plasma-modified powder in the composite additives, with its special core-shell structure, forms a dense physical support framework inside the polymethyl methacrylate matrix, effectively limiting the high-temperature slippage of polymer chains and inhibiting matrix deformation and volume shrinkage caused by temperature changes. The treatment agent optimizes the interfacial compatibility between the powder and the polymethyl methacrylate matrix, eliminates interfacial voids and defects, and blocks light scattering paths. The ionic liquid in the composite liquid medium has good compatibility with the methyl methacrylate monomer, which can optimize the overall fluidity of the polymerization system, reduce the internal stress caused by uneven molecular chain arrangement, avoid high-temperature deformation caused by residual internal stress, and optimize the visible light transmission band of the matrix by relying on the optical modulation characteristics of semiconductor nanocrystals, reducing light loss. This reduces the light scattering problems caused by agglomeration and optical defects from the source, ultimately effectively improving heat resistance and optical properties. Comparative Example 1, without composite additives, lacked high-temperature support and interface optimization of the polymethyl methacrylate matrix, resulting in a sharp drop in heat distortion temperature, a significant decrease in light transmittance, and a significant increase in haze. Comparative Example 2, using deionized water instead of composite liquid medium, lost its optical control effect, leading to high polymerization internal stress, intensified light scattering, and a simultaneous deterioration in heat resistance and optical properties. Comparative Example 3, with composite additives lacking treatment agents, only suffered from insufficient powder dispersibility and numerous interface defects, resulting in a slight decrease in light transmittance and heat resistance of the material.

[0055] By comparing and analyzing the relevant data in the table, it can be seen that the optical-grade polymethyl methacrylate material prepared by this invention not only has good heat resistance but also excellent optical properties. This indicates that the optical-grade polymethyl methacrylate material provided by this invention has a broader market prospect and is more suitable for widespread application.

[0056] In the description of this specification, references to terms such as "an embodiment," "example," "specific example," etc., indicate that a specific feature, structure, material, or characteristic described in connection with that embodiment or example is included in at least one embodiment or example of the invention. In this specification, illustrative expressions of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the specific features, structures, materials, or characteristics described may be combined in any suitable manner in one or more embodiments or examples.

[0057] The preferred embodiments of the present invention disclosed above are merely illustrative of the invention. These preferred embodiments do not exhaustively describe all details, nor do they limit the invention to the specific implementations described. Clearly, many modifications and variations can be made based on the content of this specification. This specification selects and specifically describes these embodiments to better explain the principles and practical applications of the invention, thereby enabling those skilled in the art to better understand and utilize the invention. The invention is limited only by the claims and their full scope and equivalents.

Claims

1. An optical-grade polymethyl methacrylate material, characterized in that, It includes the following raw materials in parts by weight: 95-105 parts methyl methacrylate, 200-240 parts composite liquid medium, 1.5-2.5 parts composite additives, and 0.08-0.12 parts initiator; The composite liquid medium comprises semiconductor nanocrystals and ionic liquids; The composite additive includes additives and treatment agents; The raw materials for the additive include polystyrene microspheres, anhydrous ethanol, tetraethyl orthosilicate, and ammonia. The raw materials for the treatment agent include hydroxyadamantyl acrylate, methyl acrylate, azobisisobutyronitrile, toluene, and maleic anhydride. The methyl methacrylate is pretreated before the preparation of optical-grade polymethyl methacrylate material; The pretreatment method for methyl methacrylate is as follows: methyl methacrylate is first extracted for 30 min at 35-45℃, 20-30 MPa and CO2 flow rate of 10 L / min using a supercritical CO2 extraction device with 5 wt% ethanol as the entrainer. Then, it is treated for 1-2 h at 20-25℃ and atmospheric pressure with a flow rate of 1 mL / min using a molecularly imprinted polymer column synthesized with hydroquinone as the template molecule. Finally, it is dried at 20-25℃ for 48 h with 5-10% of 3A molecular sieve by mass of methyl methacrylate.

2. The optical-grade polymethyl methacrylate material according to claim 1, characterized in that, The method for preparing the composite liquid medium is as follows: the ionic liquid is preheated to 40°C in a water bath, semiconductor nanocrystals are added, and the mixture is first ultrasonically treated at a frequency of 40kHz and a power of 200-300W for 10-15 minutes, and then magnetically stirred at 200-300rpm for 0.5-1.5 hours to obtain the composite liquid medium, wherein the mass of the semiconductor nanocrystals is 0.2-0.4% of the mass of the ionic liquid.

3. The optical-grade polymethyl methacrylate material according to claim 1, characterized in that, The semiconductor nanocrystals are a mixture of cesium lead bromide perovskite quantum dots and copper indium sulfide quantum dots in a molar ratio of 1:(1-2).

4. The optical-grade polymethyl methacrylate material according to claim 1, characterized in that, The ionic liquid is 1-butyl-3-methylimidazolium tetrafluoroborate with a water content of less than 30 ppm.

5. The optical-grade polymethyl methacrylate material according to claim 1, characterized in that, The preparation method of the composite additive is as follows: the additive and the treatment agent are mixed at a mass ratio of (0.3-0.5):(1-2) to obtain a mixture. 5-10% of 3A molecular sieve by mass is added to the mixture, and it is dried at 20-25℃ for 12h, and then vacuum dried at 55-65℃ for 12h. PEG-6000 is added to the dried mixture, and it is stirred at 70℃ and 3000-4000rpm for 20-30min to obtain the composite additive. The 3A molecular sieve is first activated in a muffle furnace at 300℃ for 2h. The pore size of the 3A molecular sieve is 0.3nm, and the mass of PEG-6000 is 8-12% of the mixture.

6. The optical-grade polymethyl methacrylate material according to claim 1, characterized in that, The preparation method of the additive is as follows: polystyrene microspheres are dispersed in anhydrous ethanol at a solid-liquid ratio of 1:(10-20), and the mixture is magnetically stirred at 200-300 rpm for 30 min at 20-30℃ to obtain a dispersion. Tetraethyl orthosilicate and ammonia water with a mass fraction of 25-30% are added to the dispersion, and the mixture is stirred at 20-30℃ for 6 h. After the reaction is completed, the mixture is centrifuged at 4000-5000 rpm for 10-15 min, and the product is collected. The product is washed with anhydrous ethanol until neutral, and then placed in a low-temperature plasma treatment instrument with argon as the carrier gas, a flow rate of 50 sccm, and a power of 100W for 5-10 min to obtain the additive. The particle size of the polystyrene microspheres is 2 μm, the mass of tetraethyl orthosilicate is 20-30% of the mass of the polystyrene microspheres, and the volume of ammonia water is 1-2% of the volume of the dispersion.

7. The optical-grade polymethyl methacrylate material according to claim 1, characterized in that, The preparation method of the treatment agent is as follows: Hydroxyadamantyl acrylate and methyl acrylate are mixed at a molar ratio of 1:(18-20), and azobisisobutyronitrile is added. The mixture is reacted at 55-65℃ for 3-5 hours under a nitrogen atmosphere. After the reaction is completed, the mixture is centrifuged at 4000-5000 rpm for 5-15 minutes. The precipitate collected by centrifugation is washed with anhydrous methanol until neutral, and then dried under vacuum at 40-50℃ and 10-30 mmHg for 24 hours. The dried product is dissolved in toluene at a solid-liquid ratio of 1:(5-10), and maleic anhydride is added. The mixture is refluxed at 75-85℃ for 2 hours to obtain the treatment agent. The mass of azobisisobutyronitrile is 0.1% of the total mass of hydroxyadamantyl acrylate and methyl acrylate, and the mass of maleic anhydride is 1-3% of the mass of the dried product.

8. The optical-grade polymethyl methacrylate material according to claim 1, characterized in that, In the pretreatment of methyl methacrylate, the 3A molecular sieve is first activated in a muffle furnace at 300℃ for 2 hours. The pore size of the 3A molecular sieve is 0.3nm. The length of the molecularly imprinted polymer column is 20-30cm and the inner diameter is 1-2cm. The particle size of the particles packed in the column is 0.1-0.3mm.

9. The optical-grade polymethyl methacrylate material according to claim 1, characterized in that, The initiator is benzoyl peroxide with a purity of ≥99% and a moisture content of ≤0.1%.

10. The method for preparing optical-grade polymethyl methacrylate material according to any one of claims 1-9, characterized in that, Includes the following steps: S1: Construction of the polymerization system: Methyl methacrylate is added to the composite liquid medium and stirred at 200-300 rpm for 30 min. Then, composite additives and initiators are added and stirred at 3000 rpm for 20 min to obtain a mixture. S2: The mixture is injected into a 2mm thick mold, sealed with polytetrafluoroethylene, prepolymerized at 35-45℃ for 1h, and then polymerized at 70-80℃ for 4-5h at a rate of 5-10℃ / h to obtain an intermediate product. Anhydrous ethanol is added to the intermediate product at a volume ratio of 1:(2-3) at 20-25℃, stirred at 200-300rpm for 30min, allowed to stand for 1h, and then centrifuged at 4000-5000rpm for 10min to obtain the crude product. S3: The crude product is dried in a vacuum drying oven at 55-65℃ and a vacuum degree of 10-30 mmHg for 24 hours to obtain optical grade polymethyl methacrylate material.

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