Continuous casting high hardness acrylic sheet and method for manufacturing the same

Abstract

The application belongs to the technical field of acrylic plates, and particularly relates to a continuous casting high-hardness acrylic plate and a preparation method thereof. Siloxane modified methyl methacrylate, methyl methacrylate and n-butyl methacrylate are mixed, an azo initiator is added thereto and stirred to obtain a prepolymer slurry; hydroxyl-terminated ether polysiloxane, isophorone diisocyanate and a catalyst dibutyltin dilaurate are mixed and reacted to obtain a macromolecular prepolymer, and then a capping agent and a photoinitiator are added thereto to obtain a coating slurry; the prepolymer slurry is injected between two synchronously operated annular steel belts, and the coating slurry is coated on the two annular steel belts, and a high-hardness acrylic plate is obtained after ultraviolet curing. The application forms a high-hardness layer on the outer part of the acrylic plate through ultraviolet curing, and the hydroxyl-terminated ether polysiloxane modified polyurethane, and the polysiloxane chain segment improves the rigidity of the soft chain segment and the hardness of the polyurethane.

Description

Technical Field

[0001] This invention belongs to the field of acrylic sheet technology, specifically relating to a continuously cast high-hardness acrylic sheet and its preparation method. Background Technology

[0002] Acrylic sheets are polymerized from methyl methacrylate monomers, chemically known as polymethyl methacrylate (PMMA). Due to their excellent light transmittance, they are also called plexiglass. Acrylic sheets are characterized by good light transmittance, resistance to cracking, good toughness, easy cleaning, and a soft texture.

[0003] However, existing acrylic sheets have low surface hardness and poor wear resistance, making them easily scratched during use. This can cause the surface to fog up, reducing the transparency of the material and limiting the use of the product.

[0004] A high-hardness, high-wear-resistant acrylic material and its preparation method are disclosed in CN118496613A. The method involves using silane liquid combined with glycolic acid to form a silane-modified liquid to modify the interface of a blending agent, a sheet graphene modifier, and polymethyl methacrylate raw materials. Through the synergistic effect of the blending agent and the sheet graphene modifier, the materials work together to enhance the hardness, wear resistance, and mechanical strength of the product.

[0005] However, simply increasing hardness by adding inorganic materials to methyl methacrylate monomers may lead to a decrease in the transparency of the material, which in turn affects its usability. Summary of the Invention

[0006] The purpose of this invention is to provide a continuously cast high-hardness acrylic sheet and its preparation method to solve the above-mentioned technical problems.

[0007] To achieve the above-mentioned technical objectives, the technical solution of the present invention is as follows:

[0008] A method for preparing continuously cast high-hardness acrylic sheets includes the following steps:

[0009] S1. Mix siloxane-modified methacrylic acid, methyl methacrylate, and n-butyl methacrylate, add an azo initiator, and stir to obtain a prepolymer slurry;

[0010] S2. Hydroxyl-terminated ether polysiloxane, isophorone diisocyanate and catalyst dibutyltin dilaurate are mixed and reacted with magnetic stirring at room temperature for 4-6 hours to obtain a macromolecular prepolymer. Then, the end-capping agent N-hydroxymethylacrylamide and the photoinitiator 2-hydroxy-2-methylphenylacetone are added to it, and stirring is continued at room temperature in the dark for 2 hours to obtain the coating slurry.

[0011] S3. The prepolymer slurry is injected between two synchronously running annular steel belts, and the coating slurry is applied to the two annular steel belts at the same time. During the operation of the annular steel belts, the prepolymer slurry is continuously polymerized through a first polymerization zone and a second polymerization zone. After being kept warm in a heat preservation zone and cooled in a cooling zone, an acrylic sheet coated with the coating slurry is obtained. The acrylic sheet coated with the coating slurry is then cured with ultraviolet light to obtain a high-hardness acrylic sheet.

[0012] As a further improvement, in step S1, the volume ratio of the siloxane-modified methacrylic acid and methyl methacrylate is 1~1.2:9, and the n-butyl methacrylate accounts for 1~20% of the total volume of the methyl methacrylate and n-butyl methacrylate.

[0013] As a further improvement, in step S1, the preparation method of the siloxane-modified methacrylic acid is as follows: the condenser, stirrer and three-necked flask are dried in an oven at 120°C for 2 hours, assembled while hot and protected with nitrogen gas, γ-epoxypropoxypropyltrimethoxysilane and methacrylic acid are added, and the catalyst triethylamine and the polymerization inhibitor hydroquinone are added under stirring conditions. The reaction is carried out at 95~105°C for 4~8 hours. After the reaction is completed, the temperature is lowered to room temperature, deionized water is added to quench the catalyst, the reactants are washed with water and allowed to stand for layering, the organic phase is separated and dried to obtain siloxane-modified methacrylic acid.

[0014] As a further improvement, the molar ratio of γ-epoxypropoxypropyltrimethoxysilane to methacrylic acid is 1:1 to 1.05, the amount of triethylamine added is 0.6% of the total mass of γ-epoxypropoxypropyltrimethoxysilane and methacrylic acid, and the mass ratio of hydroquinone to triethylamine is 2:15.

[0015] As a further improvement, the ultraviolet curing specifically involves: initiating polymerization of the acrylic sheet coated with the coating slurry under 365nm ultraviolet light for 2-2.5 hours, then immersing it in an ethanol-water mixture for 30-45 minutes, followed by immersion in distilled water for 24 hours, and finally drying it at 60°C.

[0016] As a further improvement, the temperature of the first polymerization zone is 60~80℃ and the polymerization time is 5~1440min; the polymerization temperature of the second polymerization zone is 100~140℃ and the polymerization time is 5~1440min; the temperature of the heat preservation zone is 100~140℃ and the heat preservation time is 5~1440min.

[0017] As a further improvement, in step S2, the preparation method of the hydroxyl-terminated ether polysiloxane is as follows: hydrogen-containing silicone oil and allyl hydroxyethyl ether are mixed and stirred evenly, the temperature is raised to 50°C and Karstedt catalyst is added, and then the temperature is raised to 60~70°C and reacted for 3~4 hours. After the reaction is completed, the mixture is rotary evaporated under pressure of 10~50 mbar to obtain the hydroxyl-terminated ether polysiloxane.

[0018] As a further improvement, the hydrogen content of the hydrogen-terminated silicone oil is 0.11~0.13%, the molar ratio of the hydrogen-terminated silicone oil to the allyl hydroxyethyl ether is 1:2, and the amount of Karstedt catalyst added is 0.15~0.2% of the total mass of the hydrogen-terminated silicone oil and the allyl hydroxyethyl ether.

[0019] As a further improvement, in step S2, the molar ratio of the terminal hydroxyl ether polysiloxane, isophorone diisocyanate and N-hydroxymethylacrylamide is 1:1.5:1, the amount of photoinitiator added is 0.2% of the total mass of the terminal hydroxyl ether polysiloxane and isophorone diisocyanate, and the mass ratio of the catalyst to the photoinitiator is 0.1~0.3:2.

[0020] The present invention also provides a continuously cast high-hardness acrylic sheet.

[0021] Due to the adoption of the above technical solution, the beneficial effects of the present invention are as follows:

[0022] This invention provides a continuously cast high-hardness acrylic sheet and its preparation method. A prepolymer is prepared using hydroxyl-terminated ether polysiloxane and isophorone diisocyanate as monomers and N-hydroxymethylacrylamide as a capping agent. A high-hardness layer is formed on the outside of the acrylic sheet by ultraviolet curing. The polyurethane is modified with hydroxyl-terminated ether polysiloxane. The polysiloxane segments improve the rigidity of the soft segments and increase the hardness of the polyurethane.

[0023] This invention uses siloxane-modified methacrylic acid as a modifying monomer to copolymerize and modify acrylic sheets. On the one hand, the siloxane in the modifying monomer can improve the hardness of the acrylic sheet. On the other hand, the hydroxyl groups in the modifying monomer enable the formation of hydrogen bonds between polymer molecules, increasing the intermolecular forces and further improving the hardness of the acrylic sheet.

[0024] In this invention, the modified monomer siloxane-modified methacrylic acid and methyl methacrylate are used in a specific volume ratio, which has little impact on the transparency of the acrylic sheet. While improving the hardness of the acrylic sheet, it does not affect its transparency.

[0025] In the preparation process of the high hardness layer of the present invention, N-hydroxymethylacrylamide is used as a capping agent. The presence of amide groups can increase the interaction force between polymer molecules in the high hardness layer, thereby further improving the hardness of the high hardness layer.

[0026] The high-hardness layer of this invention uses hydroxyl-terminated polysiloxane in its preparation process. The alkyl ether structure therein can improve the degree of miscibility between the oil-phase polymer network and the hydrophilic monomer of the end-capping agent, thereby improving the overall uniformity and compatibility of the polymer network. This avoids the reduction in transparency caused by the poor compatibility between the oil-phase polymer network and the end-capping agent due to the amide group. The resulting high-hardness layer has high transparency even with high hardness. Attached Figure Description

[0027] Figure 1 This is a schematic diagram of a ring-shaped steel strip. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to specific embodiments. However, those skilled in the art will understand that the embodiments described below are some embodiments of the present invention, but not all embodiments, and are only used to illustrate the present invention, and should not be regarded as limiting the scope of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall be followed. Where the manufacturers of reagents or instruments are not specified, they are all conventional products that can be purchased commercially.

[0029] In this invention, the hydrogen content of the hydrogen-terminated silicone oil is 0.11~0.13%, and its molar mass is 1550~1832 g / mol.

[0030] Example 1: A method for preparing a continuously cast high-hardness acrylic sheet, specifically including the following steps:

[0031] S1. The condenser, stirrer and three-necked flask were dried in an oven at 120℃ for 2 hours. They were assembled while hot and protected with nitrogen. 118.17 g (0.5 mol) of γ-epoxypropoxypropyltrimethoxysilane and 43.05 g (0.5 mol) of methacrylic acid were added. Under stirring, 0.97 g of triethylamine (TEA) catalyst and 0.13 g of hydroquinone polymerization inhibitor were added. The reaction was carried out at 95℃ for 8 hours. After the reaction was completed, the temperature was lowered to room temperature and 20 mL of deionized water was added to quench the catalyst. The reactants were washed with water and allowed to stand for separation. The organic phase was separated and dried with sodium sulfate to obtain siloxane-modified methacrylic acid.

[0032] The specific reaction equation is as follows:

[0033] ;

[0034] S2. Using siloxane-modified methacrylic acid as the modifying monomer, 500 mL of methyl methacrylate, 55.56 mL of the modifying monomer, and 5.05 mL of n-butyl methacrylate were mixed. 0.56 g of initiator azobisisobutyronitrile was added and the mixture was stirred to obtain a prepolymer slurry.

[0035] S3. Mix 15.5g (10mmol) of hydrogen-terminated silicone oil and 2.04g (20mmol) of allyl hydroxyethyl ether evenly, heat to 50℃ and add 0.026g of Karstedt catalyst, then heat to 60℃ and react for 4h. After the reaction is complete, rotary evaporate under 10mbar pressure to obtain hydroxyl-terminated ether polysiloxane.

[0036] The specific reaction equation is as follows:

[0037] ;

[0038] S4. Mix 17.54 g (10 mmol) of hydroxyl-terminated ether polysiloxane, 3.33 g (15 mmol) of isophorone diisocyanate and 2.10 mg of catalyst dibutyltin dilaurate, and react with magnetic stirring at room temperature for 4 h to obtain a macromolecular prepolymer. Then add 1.01 g (10 mmol) of end-capping agent N-hydroxymethylacrylamide and 0.042 g of photoinitiator 2-hydroxy-2-methylphenylacetone to it, and continue stirring at room temperature in the dark for 2 h to obtain a coating slurry.

[0039] S5. The prepolymer slurry is injected between two synchronously running annular steel belts, and the coating slurry is applied to the outer wall of the two annular steel belts. During the movement of the annular steel belts, the prepolymer slurry passes through a first polymerization zone, a second polymerization zone, a heat preservation zone and a cooling zone in sequence to obtain an acrylic sheet coated with the coating slurry. The continuous casting preparation method of the acrylic sheet is an existing technology.

[0040] The polymerization zone has a temperature of 60℃ and a polymerization time of 1440 min; the polymerization zone has a polymerization temperature of 100℃ and a polymerization time of 1440 min; and the insulation zone has a temperature of 100℃ and an insulation time of 1440 min.

[0041] S6. Place the acrylic sheet coated with the coating slurry in a 365nm ultraviolet lamp box to initiate polymerization for 2 hours, then soak it in an ethanol-water mixed solution (ethanol and water volume ratio of 1:1) for 30 minutes, then soak it in distilled water for 24 hours, and finally dry it at 60°C to obtain a high-hardness acrylic sheet.

[0042] In this embodiment, a schematic diagram of the annular steel strip is shown below. Figure 1 As shown.

[0043] In this embodiment, after the coating slurry is cured by light, a high-hardness layer is formed on the outside of the acrylic sheet. The acrylic sheet obtained in this embodiment has high hardness and good transparency due to the adhesion of the high-hardness layer.

[0044] Example 2: A method for preparing a continuously cast high-hardness acrylic sheet, specifically including the following steps:

[0045] S1. The condenser, stirrer and three-necked flask were dried in an oven at 120℃ for 2 hours. They were assembled while hot and protected with nitrogen. 118.17 g (0.5 mol) of γ-epoxypropoxypropyltrimethoxysilane and 45.20 g (0.525 mol) of methacrylic acid were added. Under stirring, 0.98 g of triethylamine (TEA) catalyst and 0.13 g of hydroquinone polymerization inhibitor were added. The reaction was carried out at 105℃ for 4 hours. After the reaction was completed, the temperature was lowered to room temperature and 20 mL of deionized water was added to quench the catalyst. The reactants were washed with water and allowed to stand for separation. The organic phase was separated and dried with sodium sulfate to obtain siloxane-modified methacrylic acid.

[0046] S2. Using siloxane-modified methacrylic acid as the modifying monomer, 500 mL of methyl methacrylate, 66.67 mL of the modifying monomer, and 125 mL of n-butyl methacrylate were mixed. 0.69 g of initiator azobisisobutyronitrile was added and the mixture was stirred to obtain a prepolymer slurry.

[0047] S3. Mix 18.32 g (10 mmol) of hydrogen-terminated silicone oil and 2.04 g (20 mmol) of allyl hydroxyethyl ether evenly, heat to 50 °C, add 0.041 g of Karstedt catalyst, then heat to 70 °C and react for 3 h. After the reaction is complete, rotary evaporate under 50 mbar pressure to obtain hydroxyl-terminated ether polysiloxane.

[0048] S4. Mix 20.36 g (10 mmol) of hydroxyl-terminated ether polysiloxane, 3.33 g (15 mmol) of isophorone diisocyanate and 7.05 mg of catalyst dibutyltin dilaurate, and react with magnetic stirring at room temperature for 6 h to obtain a macromolecular prepolymer. Then add 1.01 g (10 mmol) of end-capping agent N-hydroxymethylacrylamide and 0.047 g of photoinitiator 2-hydroxy-2-methylphenylacetone to it, and continue stirring at room temperature in the dark for 2 h to obtain a coating slurry.

[0049] S5. Inject the prepolymer slurry between two synchronously running annular steel belts, and at the same time apply the coating slurry to the outer wall of the two annular steel belts. During the movement of the annular steel belts, the prepolymer slurry passes through a first polymerization zone, a second polymerization zone, a heat preservation zone and a cooling zone in sequence to obtain an acrylic sheet coated with the coating slurry.

[0050] The polymerization zone has a temperature of 80℃ and a polymerization time of 5 minutes; the polymerization temperature of the second polymerization zone is 140℃ and the polymerization time is 5 minutes; and the temperature of the heat preservation zone is 140℃ and the heat preservation time is 5 minutes.

[0051] S6. Place the acrylic sheet coated with the coating slurry in a 365nm ultraviolet light box to initiate polymerization for 2.5h, then soak it in an ethanol-water mixed solution (ethanol and water volume ratio of 1:1) for 45min, then soak it in distilled water for 24h, and finally dry it at 60℃ to obtain a high-hardness acrylic sheet.

[0052] Example 3: A method for preparing a continuously cast high-hardness acrylic sheet, specifically including the following steps:

[0053] S1. The condenser, stirrer and three-necked flask were dried in an oven at 120℃ for 2 hours. They were assembled while hot and protected with nitrogen. 118.17 g (0.5 mol) of γ-epoxypropoxypropyltrimethoxysilane and 44.12 g (0.5125 mol) of methacrylic acid were added. Under stirring, 0.97 g of triethylamine (TEA) catalyst and 0.13 g of hydroquinone polymerization inhibitor were added. The reaction was carried out at 100℃ for 6 hours. After the reaction was completed, the temperature was lowered to room temperature and 20 mL of deionized water was added to quench the catalyst. The reactants were washed with water and allowed to stand for separation. The organic phase was separated and dried with sodium sulfate to obtain siloxane-modified methacrylic acid.

[0054] S2. Using siloxane-modified methacrylic acid as the modifying monomer, 500 mL of methyl methacrylate, 61.11 mL of the modifying monomer, and 111.11 mL of n-butyl methacrylate were mixed. 0.67 g of initiator dimethyl azobisisobutyrate was added and the mixture was stirred to obtain a prepolymer slurry.

[0055] S3. Mix 17.00 g (10 mmol) of hydrogen-terminated silicone oil and 2.04 g (20 mmol) of allyl hydroxyethyl ether and stir until homogeneous. Heat to 50 °C and add 0.034 g of Karstedt catalyst. Then heat to 65 °C and react for 3.5 h. After the reaction is complete, rotary evaporate under 30 mbar pressure to obtain hydroxyl-terminated ether polysiloxane.

[0056] S4. Mix 19.04 g (10 mmol) of hydroxyl-terminated ether polysiloxane, 3.33 g (15 mmol) of isophorone diisocyanate and 4.5 mg of catalyst dibutyltin dilaurate, and react with magnetic stirring at room temperature for 5 h to obtain a macromolecular prepolymer. Then add 1.01 g (10 mmol) of end-capping agent N-hydroxymethylacrylamide and 0.045 g of photoinitiator 2-hydroxy-2-methylphenylacetone to it, and continue stirring at room temperature in the dark for 2 h to obtain a coating slurry.

[0057] S5. Inject the prepolymer slurry between two synchronously running annular steel belts, and at the same time apply the coating slurry to the outer wall of the two annular steel belts. During the movement of the annular steel belts, the prepolymer slurry passes through a first polymerization zone, a second polymerization zone, a heat preservation zone and a cooling zone in sequence to obtain an acrylic sheet coated with the coating slurry.

[0058] The polymerization zone has a temperature of 70℃ and a polymerization time of 1000 min; the polymerization temperature of the second polymerization zone is 120℃ and the polymerization time is 1000 min; and the temperature of the heat preservation zone is 120℃ and the heat preservation time is 1000 min.

[0059] S6. Place the acrylic sheet coated with the coating slurry in a 365nm ultraviolet light box to initiate polymerization for 2.3h, then soak it in an ethanol-water mixed solution (ethanol and water volume ratio of 1:1) for 38min, then soak it in distilled water for 24h, and finally dry it at 60℃ to obtain a high-hardness acrylic sheet.

[0060] Example 4: A method for preparing a continuously cast high-hardness acrylic sheet, specifically including the following steps:

[0061] S1. The condenser, stirrer and three-necked flask were dried in an oven at 120℃ for 2 hours. They were assembled while hot and protected with nitrogen. 118.17 g (0.5 mol) of γ-epoxypropoxypropyltrimethoxysilane and 44.12 g (0.5125 mol) of methacrylic acid were added. Under stirring, 0.97 g of triethylamine (TEA) catalyst and 0.13 g of hydroquinone polymerization inhibitor were added. The reaction was carried out at 100℃ for 6 hours. After the reaction was completed, the temperature was lowered to room temperature and 20 mL of deionized water was added to quench the catalyst. The reactants were washed with water and allowed to stand for separation. The organic phase was separated and dried with sodium sulfate to obtain siloxane-modified methacrylic acid.

[0062] S2. Using siloxane-modified methacrylic acid as the modifying monomer, 500 mL of methyl methacrylate, 63.89 mL of the modifying monomer, and 105.26 mL of n-butyl methacrylate were mixed. 0.67 g of initiator dimethyl azobisisobutyrate was added and the mixture was stirred to obtain a prepolymer slurry.

[0063] S3. Mix 17.00 g (10 mmol) of hydrogen-terminated silicone oil and 2.04 g (20 mmol) of allyl hydroxyethyl ether and stir until homogeneous. Heat to 50 °C and add 0.034 g of Karstedt catalyst. Then heat to 65 °C and react for 3.5 h. After the reaction is complete, rotary evaporate under 30 mbar pressure to obtain hydroxyl-terminated ether polysiloxane.

[0064] S4. Mix 19.04 g (10 mmol) of hydroxyl-terminated ether polysiloxane, 3.33 g (15 mmol) of isophorone diisocyanate and 4.5 mg of catalyst dibutyltin dilaurate, and react with magnetic stirring at room temperature for 5 h to obtain a macromolecular prepolymer. Then add 1.01 g (10 mmol) of end-capping agent N-hydroxymethylacrylamide and 0.045 g of photoinitiator 2-hydroxy-2-methylphenylacetone to it, and continue stirring at room temperature in the dark for 2 h to obtain a coating slurry.

[0065] S5. Inject the prepolymer slurry between two synchronously running annular steel belts, and at the same time apply the coating slurry to the outer wall of the two annular steel belts. During the movement of the annular steel belts, the prepolymer slurry passes through a first polymerization zone, a second polymerization zone, a heat preservation zone and a cooling zone in sequence to obtain an acrylic sheet coated with the coating slurry.

[0066] The polymerization zone has a temperature of 65℃ and a polymerization time of 500 min; the polymerization temperature of the second polymerization zone is 115℃ and the polymerization time is 500 min; and the temperature of the heat preservation zone is 115℃ and the heat preservation time is 500 min.

[0067] S6. Place the acrylic sheet coated with the coating slurry in a 365nm ultraviolet light box to initiate polymerization for 2.2h, then soak it in an ethanol-water mixed solution (ethanol and water volume ratio of 1:1) for 38min, then soak it in distilled water for 24h, and finally dry it at 60℃ to obtain a high-hardness acrylic sheet.

[0068] Example 5: A method for preparing a continuously cast high-hardness acrylic sheet, specifically including the following steps:

[0069] S1. The condenser, stirrer and three-necked flask were dried in an oven at 120℃ for 2 hours. They were assembled while hot and protected with nitrogen. 118.17 g (0.5 mol) of γ-epoxypropoxypropyltrimethoxysilane and 44.12 g (0.5125 mol) of methacrylic acid were added. Under stirring, 0.97 g of triethylamine (TEA) catalyst and 0.13 g of hydroquinone polymerization inhibitor were added. The reaction was carried out at 100℃ for 6 hours. After the reaction was completed, the temperature was lowered to room temperature and 20 mL of deionized water was added to quench the catalyst. The reactants were washed with water and allowed to stand for separation. The organic phase was separated and dried with sodium sulfate to obtain siloxane-modified methacrylic acid.

[0070] S2. Using siloxane-modified methacrylic acid as the modifying monomer, 500 mL of methyl methacrylate, 58.33 mL of the modifying monomer, and 117.65 mL of n-butyl methacrylate were mixed. 0.68 g of initiator dimethyl azobisisobutyrate was added and the mixture was stirred to obtain a prepolymer slurry.

[0071] S3. Mix 17.00 g (10 mmol) of hydrogen-terminated silicone oil and 2.04 g (20 mmol) of allyl hydroxyethyl ether and stir until homogeneous. Heat to 50 °C and add 0.034 g of Karstedt catalyst. Then heat to 65 °C and react for 3.5 h. After the reaction is complete, rotary evaporate under 30 mbar pressure to obtain hydroxyl-terminated ether polysiloxane.

[0072] S4. Mix 19.04 g (10 mmol) of hydroxyl-terminated ether polysiloxane, 3.33 g (15 mmol) of isophorone diisocyanate and 4.5 mg of catalyst dibutyltin dilaurate, and react with magnetic stirring at room temperature for 5 h to obtain a macromolecular prepolymer. Then add 1.01 g (10 mmol) of end-capping agent N-hydroxymethylacrylamide and 0.045 g of photoinitiator 2-hydroxy-2-methylphenylacetone to it, and continue stirring at room temperature in the dark for 2 h to obtain a coating slurry.

[0073] S5. Inject the prepolymer slurry between two synchronously running annular steel belts, and at the same time apply the coating slurry to the outer wall of the two annular steel belts. During the movement of the annular steel belts, the prepolymer slurry passes through a first polymerization zone, a second polymerization zone, a heat preservation zone and a cooling zone in sequence to obtain an acrylic sheet coated with the coating slurry.

[0074] The polymerization zone has a temperature of 65℃ and a polymerization time of 300 min; the polymerization zone has a polymerization temperature of 115℃ and a polymerization time of 300 min; and the heat preservation zone has a temperature of 115℃ and a heat preservation time of 300 min.

[0075] S6. Place the acrylic sheet coated with the coating slurry in a 365nm ultraviolet light box to initiate polymerization for 2.2h, then soak it in an ethanol-water mixed solution (ethanol and water volume ratio of 1:1) for 38min, then soak it in distilled water for 24h, and finally dry it at 60℃ to obtain a high-hardness acrylic sheet.

[0076] Example 6: A method for preparing a continuously cast high-hardness acrylic sheet, specifically including the following steps:

[0077] S1. The condenser, stirrer and three-necked flask were dried in an oven at 120℃ for 2 hours. They were assembled while hot and protected with nitrogen. 118.17 g (0.5 mol) of γ-epoxypropoxypropyltrimethoxysilane and 44.12 g (0.5125 mol) of methacrylic acid were added. Under stirring, 0.97 g of triethylamine (TEA) catalyst and 0.13 g of hydroquinone polymerization inhibitor were added. The reaction was carried out at 100℃ for 6 hours. After the reaction was completed, the temperature was lowered to room temperature and 20 mL of deionized water was added to quench the catalyst. The reactants were washed with water and allowed to stand for separation. The organic phase was separated and dried with sodium sulfate to obtain siloxane-modified methacrylic acid.

[0078] S2. Using siloxane-modified methacrylic acid as the modifying monomer, 500 mL of methyl methacrylate, 58.33 mL of the modifying monomer, and 117.65 mL of n-butyl methacrylate were mixed. 0.68 g of initiator dimethyl azobisisobutyrate was added and the mixture was stirred to obtain a prepolymer slurry.

[0079] S3. Mix 17.00 g (10 mmol) of hydrogen-terminated silicone oil and 2.04 g (20 mmol) of allyl hydroxyethyl ether and stir until homogeneous. Heat to 50 °C and add 0.034 g of Karstedt catalyst. Then heat to 65 °C and react for 3.5 h. After the reaction is complete, rotary evaporate under 30 mbar pressure to obtain hydroxyl-terminated ether polysiloxane.

[0080] S4. Mix 19.04 g (10 mmol) of hydroxyl-terminated ether polysiloxane, 3.33 g (15 mmol) of isophorone diisocyanate and 4.5 mg of catalyst dibutyltin dilaurate, and react with magnetic stirring at room temperature for 5 h to obtain a macromolecular prepolymer. Then add 1.01 g (10 mmol) of end-capping agent N-hydroxymethylacrylamide and 0.045 g of photoinitiator 2-hydroxy-2-methylphenylacetone to it, and continue stirring at room temperature in the dark for 2 h to obtain a coating slurry.

[0081] S5. Inject the prepolymer slurry between two synchronously running annular steel belts, and at the same time apply the coating slurry to the outer wall of the two annular steel belts. During the movement of the annular steel belts, the prepolymer slurry passes through a first polymerization zone, a second polymerization zone, a heat preservation zone and a cooling zone in sequence to obtain an acrylic sheet coated with the coating slurry.

[0082] The polymerization zone has a temperature of 75℃ and a polymerization time of 200 min; the polymerization zone has a polymerization temperature of 105℃ and a polymerization time of 200 min; and the heat preservation zone has a temperature of 105℃ and a heat preservation time of 200 min.

[0083] S6. Place the acrylic sheet coated with the coating slurry in a 365nm ultraviolet light box to initiate polymerization for 2.2h, then soak it in an ethanol-water mixed solution (ethanol and water volume ratio of 1:1) for 38min, then soak it in distilled water for 24h, and finally dry it at 60℃ to obtain a high-hardness acrylic sheet.

[0084] Example 7 A method for preparing a continuously cast high-hardness acrylic sheet, specifically including the following steps:

[0085] S1. The condenser, stirrer and three-necked flask were dried in an oven at 120℃ for 2 hours. They were assembled while hot and protected with nitrogen. 118.17 g (0.5 mol) of γ-epoxypropoxypropyltrimethoxysilane and 44.12 g (0.5125 mol) of methacrylic acid were added. Under stirring, 0.97 g of triethylamine (TEA) catalyst and 0.13 g of hydroquinone polymerization inhibitor were added. The reaction was carried out at 100℃ for 6 hours. After the reaction was completed, the temperature was lowered to room temperature and 20 mL of deionized water was added to quench the catalyst. The reactants were washed with water and allowed to stand for separation. The organic phase was separated and dried with sodium sulfate to obtain siloxane-modified methacrylic acid.

[0086] S2. Using siloxane-modified methacrylic acid as the modifying monomer, 500 mL of methyl methacrylate, 58.33 mL of the modifying monomer, and 117.65 mL of n-butyl methacrylate were mixed. 0.68 g of initiator dimethyl azobisisobutyrate was added and the mixture was stirred to obtain a prepolymer slurry.

[0087] S3. Mix 17.00 g (10 mmol) of hydrogen-terminated silicone oil and 2.04 g (20 mmol) of allyl hydroxyethyl ether and stir until homogeneous. Heat to 50 °C and add 0.034 g of Karstedt catalyst. Then heat to 65 °C and react for 3.5 h. After the reaction is complete, rotary evaporate under 30 mbar pressure to obtain hydroxyl-terminated ether polysiloxane.

[0088] S4. Mix 19.04 g (10 mmol) of hydroxyl-terminated ether polysiloxane, 3.33 g (15 mmol) of isophorone diisocyanate and 4.5 mg of catalyst dibutyltin dilaurate, and react with magnetic stirring at room temperature for 5 h to obtain a macromolecular prepolymer. Then add 1.01 g (10 mmol) of end-capping agent N-hydroxymethylacrylamide and 0.045 g of photoinitiator 2-hydroxy-2-methylphenylacetone to it, and continue stirring at room temperature in the dark for 2 h to obtain a coating slurry.

[0089] S5. Inject the prepolymer slurry between two synchronously running annular steel belts, and at the same time apply the coating slurry to the outer wall of the two annular steel belts. During the movement of the annular steel belts, the prepolymer slurry passes through a first polymerization zone, a second polymerization zone, a heat preservation zone and a cooling zone in sequence to obtain an acrylic sheet coated with the coating slurry.

[0090] The polymerization zone has a temperature of 75℃ and a polymerization time of 100 min; the polymerization zone has a polymerization temperature of 105℃ and a polymerization time of 100 min; and the heat preservation zone has a temperature of 105℃ and a heat preservation time of 100 min.

[0091] S6. Place the acrylic sheet coated with the coating slurry in a 365nm ultraviolet light box to initiate polymerization for 2.2h, then soak it in an ethanol-water mixed solution (ethanol and water volume ratio of 1:1) for 38min, then soak it in distilled water for 24h, and finally dry it at 60℃ to obtain a high-hardness acrylic sheet.

[0092] Comparative Example 1: This comparative example provides a continuously cast acrylic sheet, prepared using the same method as Example 1. The difference from Example 1 is that, in the preparation of the coating slurry, the hydroxyl-terminated ether polysiloxane is replaced with a hydroxyl-terminated hydrocarbon polysiloxane, as detailed below:

[0093] S1. Mix 15.5g (10mmol) of hydrogen-terminated silicone oil and 1.72g (20mmol) of tetraendipentol until homogeneous. Heat to 50°C and add 0.026g of Karstedt catalyst. Then heat to 60°C and react for 4h. After the reaction is complete, rotary evaporate under 10mbar pressure to obtain hydroxyl-terminated polysiloxane.

[0094] S2. Mix 17.22 g (10 mmol) of hydroxyl-terminated polysiloxane, 3.33 g (15 mmol) of isophorone diisocyanate and 2.05 mg of catalyst dibutyltin dilaurate, and react with magnetic stirring at room temperature for 4 h to obtain a macromolecular prepolymer. Then add 1.01 g (10 mmol) of end-capping agent N-hydroxymethylacrylamide and 0.041 g of photoinitiator 2-hydroxy-2-methylphenylacetone to it, and continue stirring at room temperature in the dark for 2 h to obtain a coating slurry.

[0095] Comparative Example 2: This comparative example provides a continuously cast acrylic sheet, prepared using the same method as Example 1. The difference from Example 1 is that hydroxyethyl methacrylate is used as a sealing agent in the preparation of the coating slurry, as detailed below:

[0096] S1. Mix 15.5g (10mmol) of hydrogen-terminated silicone oil and 2.04g (20mmol) of allyl hydroxyethyl ether evenly, heat to 50℃ and add 0.026g of Karstedt catalyst, then heat to 60℃ and react for 4h. After the reaction is complete, rotary evaporate under 10mbar pressure to obtain hydroxyl-terminated ether polysiloxane.

[0097] S2. Mix 17.54 g (10 mmol) of hydroxyl-terminated polysiloxane, 3.33 g (15 mmol) of isophorone diisocyanate and 2.10 mg of catalyst dibutyltin dilaurate, and react with magnetic stirring at room temperature for 4 h to obtain a macromolecular prepolymer. Then add 1.31 g (10 mmol) of end-capping agent hydroxyethyl methacrylate and 0.042 g of photoinitiator 2-hydroxy-2-methylphenylacetone to it, and continue stirring at room temperature in the dark for 2 h to obtain the coating slurry.

[0098] Comparative Example 3: This comparative example provides a continuously cast acrylic sheet, prepared using the same method as Example 1. The difference from Example 1 is that, in the preparation of the coating slurry, the hydroxyl-terminated ether polysiloxane is replaced with a hydroxyl-terminated hydrocarbon polysiloxane, and hydroxyethyl methacrylate is used as the end-capping agent, as detailed below:

[0099] S1. Mix 15.5g (10mmol) of hydrogen-terminated silicone oil and 1.72g (20mmol) of tetraendipentol until homogeneous. Heat to 50°C and add 0.026g of Karstedt catalyst. Then heat to 60°C and react for 4h. After the reaction is complete, rotary evaporate under 10mbar pressure to obtain hydroxyl-terminated polysiloxane.

[0100] S2. Mix 17.22 g (10 mmol) of hydroxyl-terminated polysiloxane, 3.33 g (15 mmol) of isophorone diisocyanate and 2.05 mg of catalyst dibutyltin dilaurate, and react with magnetic stirring at room temperature for 4 h to obtain a macromolecular prepolymer. Then add 1.31 g (10 mmol) of end-capping agent hydroxyethyl methacrylate and 0.041 g of photoinitiator 2-hydroxy-2-methylphenylacetone to the mixture, and continue stirring at room temperature in the dark for 2 h to obtain a coating slurry.

[0101] The acrylic sheets obtained in Example 1 and Comparative Examples 1-3 were subjected to hardness and transparency tests. Surface hardness test: In accordance with GB / T 2411-2008, the hardness of the acrylic sheets was tested using a Shore D hardness tester. Five scattered points were selected for measurement for each sample, and the average value was taken as the Shore hardness of the sample. Transmittance test: In accordance with GB / T 2410-2008, the transmittance of the acrylic sheets at a wavelength of 600 nm was measured using a UV-Vis spectrophotometer. The transmittance and hardness test results are shown in Table 1.

[0102] Table 1. Test results of hardness and transparency of acrylic sheets in Example 1 and Comparative Examples 1-3

[0103] ;

[0104] As shown in Table 1, the transmittance of the acrylic sheet in Comparative Example 1 is significantly lower than that in Example 1. This is because the amide groups in the end-capping agent lead to poor compatibility between the oil-phase polymer network and the end-capping agent, resulting in reduced transparency. The hardness of the acrylic sheet in Comparative Example 2 is significantly lower than that in Example 1, indicating that the addition of amide groups in the end-capping agent is beneficial to improving the hardness of the high-hardness layer. Based on Comparative Example 2, Comparative Example 3 replaces the hydroxyl-terminated ether polysiloxane with a hydroxyl-terminated hydrocarbon polysiloxane. The resulting acrylic sheet has a transparency that is similar to, or slightly higher than, that of Examples 1 and 2. This further demonstrates that the alkyl ether structure can avoid the reduction in transparency caused by poor compatibility between the oil-phase polymer network and the end-capping agent due to the amide groups.

[0105] Comparative Example 4: This comparative example provides a continuously cast acrylic sheet, which differs from Example 1 in that it does not use a coating slurry, resulting in an acrylic sheet without a high-hardness layer. The specific steps include:

[0106] S1. The condenser, stirrer and three-necked flask were dried in an oven at 120℃ for 2 hours. They were assembled while hot and protected with nitrogen. 118.17 g (0.5 mol) of γ-epoxypropoxypropyltrimethoxysilane and 43.05 g (0.5 mol) of methacrylic acid were added. Under stirring, 0.97 g of triethylamine (TEA) catalyst and 0.13 g of hydroquinone polymerization inhibitor were added. The reaction was carried out at 95℃ for 8 hours. After the reaction was completed, the temperature was lowered to room temperature and 20 mL of deionized water was added to quench the catalyst. The reactants were washed with water and allowed to stand for separation. The organic phase was separated and dried with sodium sulfate to obtain siloxane-modified methacrylic acid.

[0107] S2. Using siloxane-modified methacrylic acid as the modifying monomer, 500 mL of methyl methacrylate, 55.56 mL of the modifying monomer, and 5.05 mL of n-butyl methacrylate were mixed. 0.56 g of initiator azobisisobutyronitrile was added and the mixture was stirred to obtain a prepolymer slurry.

[0108] S3. The prepolymer slurry is injected between two synchronously running annular steel belts. During the movement of the annular steel belts, the prepolymer slurry passes through a first polymerization zone, a second polymerization zone, an insulation zone, and a cooling zone in sequence to obtain an acrylic sheet. The continuous casting method for preparing the acrylic sheet is an existing technology.

[0109] The polymerization zone has a temperature of 60℃ and a polymerization time of 1440 min; the polymerization temperature of the second polymerization zone is 100℃ and the polymerization time is 1440 min; and the temperature of the heat preservation zone is 100℃ and the heat preservation time is 1440 min.

[0110] Comparative Example 5: This comparative example provides a continuously cast acrylic sheet, which is prepared using the same method as Comparative Example 4, except that ethyl methacrylate is used as a modifying monomer in the preparation of the prepolymer slurry, as detailed below:

[0111] Using ethyl methacrylate as a modifying monomer, 500 mL of methyl methacrylate, 55.56 mL of the modifying monomer, and 5.05 mL of n-butyl methacrylate were mixed, and 0.56 g of azobisisobutyronitrile (AIBN) initiator was added and stirred to obtain a prepolymer slurry.

[0112] Comparative Example 6: This comparative example provides a continuously cast acrylic sheet, which is prepared in the same way as Comparative Example 4, except that in the preparation of the prepolymer slurry, the volume ratio of the modified monomer siloxane-modified methacrylic acid and methyl methacrylate is 2:8, as detailed below:

[0113] S1. The condenser, stirrer and three-necked flask were dried in an oven at 120°C for 2 hours. They were assembled while hot and protected with nitrogen. 118.17 g (0.5 mol) of γ-epoxypropoxypropyltrimethoxysilane and 43.05 g (0.5 mol) of methacrylic acid were added. Under stirring, 0.97 g of triethylamine catalyst and 0.13 g of hydroquinone polymerization inhibitor were added. The reaction was carried out at 95°C for 8 hours. After the reaction was completed, the temperature was lowered to room temperature and 20 mL of deionized water was added to quench the catalyst. The reactants were washed with water and allowed to stand for separation. The organic phase was separated and dried with sodium sulfate to obtain siloxane-modified methacrylic acid.

[0114] S2. Using siloxane-modified methacrylic acid as the modifying monomer, 500 mL of methyl methacrylate, 125 mL of the modifying monomer, and 5.05 mL of n-butyl methacrylate were mixed, and 0.63 g of initiator azobisisobutyronitrile was added and stirred to obtain a prepolymer slurry.

[0115] Comparative Example 7: This comparative example provides a continuously cast acrylic sheet, prepared using the same method as Comparative Example 4, except that the volume ratio of the modified monomer siloxane-modified methacrylic acid to methyl methacrylate is 0.5:9.5 during the preparation of the prepolymer slurry, as detailed below:

[0116] S1. The condenser, stirrer and three-necked flask were dried in an oven at 120°C for 2 hours. They were assembled while hot and protected with nitrogen. 118.17 g (0.5 mol) of γ-epoxypropoxypropyltrimethoxysilane and 43.05 g (0.5 mol) of methacrylic acid were added. Under stirring, 0.97 g of triethylamine catalyst and 0.13 g of hydroquinone polymerization inhibitor were added. The reaction was carried out at 95°C for 8 hours. After the reaction was completed, the temperature was lowered to room temperature and 20 mL of deionized water was added to quench the catalyst. The reactants were washed with water and allowed to stand for separation. The organic phase was separated and dried with sodium sulfate to obtain siloxane-modified methacrylic acid.

[0117] S2. Using siloxane-modified methacrylic acid as the modifying monomer, 500 mL of methyl methacrylate, 26.32 mL of the modifying monomer, and 5.05 mL of n-butyl methacrylate were mixed. 0.53 g of initiator azobisisobutyronitrile was added and the mixture was stirred to obtain a prepolymer slurry.

[0118] Comparative Example 8: This comparative example provides a continuously cast acrylic sheet, prepared using the same method as Comparative Example 4, except that the volume ratio of the modified monomer siloxane-modified methacrylic acid to methyl methacrylate is 0.1:9.9 during the prepolymer slurry preparation process, as detailed below:

[0119] S1. The condenser, stirrer and three-necked flask were dried in an oven at 120°C for 2 hours. They were assembled while hot and protected with nitrogen. 118.17 g (0.5 mol) of γ-epoxypropoxypropyltrimethoxysilane and 43.05 g (0.5 mol) of methacrylic acid were added. Under stirring, 0.97 g of triethylamine catalyst and 0.13 g of hydroquinone polymerization inhibitor were added. The reaction was carried out at 95°C for 8 hours. After the reaction was completed, the temperature was lowered to room temperature and 20 mL of deionized water was added to quench the catalyst. The reactants were washed with water and allowed to stand for separation. The organic phase was separated and dried with sodium sulfate to obtain siloxane-modified methacrylic acid.

[0120] S2. Using siloxane-modified methacrylic acid as the modifying monomer, 500 mL of methyl methacrylate, 5.05 mL of the modifying monomer, and 5.05 mL of n-butyl methacrylate were mixed. 0.51 g of initiator azobisisobutyronitrile was added and the mixture was stirred to obtain a prepolymer slurry.

[0121] Comparative Example 9: This comparative example provides a continuously cast acrylic sheet, prepared using the same method as Comparative Example 4, except that the volume ratio of the modified monomer siloxane-modified methacrylic acid to methyl methacrylate is 3:7 during the preparation of the prepolymer slurry, as detailed below:

[0122] S1. The condenser, stirrer and three-necked flask were dried in an oven at 120°C for 2 hours. They were assembled while hot and protected with nitrogen. 118.17 g (0.5 mol) of γ-epoxypropoxypropyltrimethoxysilane and 43.05 g (0.5 mol) of methacrylic acid were added. Under stirring, 0.97 g of triethylamine catalyst and 0.13 g of hydroquinone polymerization inhibitor were added. The reaction was carried out at 95°C for 8 hours. After the reaction was completed, the temperature was lowered to room temperature and 20 mL of deionized water was added to quench the catalyst. The reactants were washed with water and allowed to stand for separation. The organic phase was separated and dried with sodium sulfate to obtain siloxane-modified methacrylic acid.

[0123] S2. Using siloxane-modified methacrylic acid as the modifying monomer, 500 mL of methyl methacrylate, 214.29 mL of the modifying monomer, and 5.05 mL of n-butyl methacrylate were mixed. 0.72 g of initiator azobisisobutyronitrile was added and the mixture was stirred to obtain a prepolymer slurry.

[0124] The acrylic sheets obtained in Comparative Examples 4-9 were subjected to hardness and transparency tests. Surface hardness test: In accordance with GB / T2411-2008, the hardness of the acrylic sheets was tested using a Shore D hardness tester. Five scattered points were selected for measurement for each sample, and the average value was taken as the Shore hardness of the sample. Transmittance test: In accordance with GB / T 2410-2008, the transmittance of the acrylic sheets at a wavelength of 600nm was measured using a UV-Vis spectrophotometer. The transmittance and hardness test results are shown in Table 2.

[0125] Table 2. Hardness and light transmittance results of acrylic sheets in Comparative Examples 4-9

[0126] ;

[0127] As shown in Table 2, Comparative Example 5, which uses methacrylate as a modified monomer to copolymerize and modify polymethyl methacrylate, has the lowest hardness of the resulting acrylic substrate. In Comparative Examples 7 and 8, the amount of modified methacrylate with siloxane is reduced compared to Comparative Example 4, resulting in a certain degree of decrease in the hardness of the acrylic sheets. However, the light transmittance is similar to that of Comparative Example 4. This indicates that modified methacrylate with siloxane can improve the hardness of the acrylic sheet, and under certain conditions, it has little effect on the light transmittance of the acrylic sheet.

[0128] In Comparative Examples 6 and 9, the amount of modified monomer siloxane-modified methacrylic acid was increased compared to Comparative Example 4. The resulting acrylic sheets had a slightly higher hardness than those in Comparative Example 4, but the light transmittance decreased significantly. This is because the siloxane-modified methacrylic acid has poor compatibility with methyl methacrylate, resulting in uneven dispersion of the system and easy agglomeration, which in turn affects the light transmittance of the material.

[0129] The specific embodiments of the present invention described above do not constitute a limitation on the scope of protection of the present invention. Any other corresponding changes and modifications made in accordance with the technical concept of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A method for preparing continuously cast high-hardness acrylic sheets, characterized in that, Includes the following steps: S1. Mix siloxane-modified methacrylic acid, methyl methacrylate, and n-butyl methacrylate, add an azo initiator, and stir to obtain a prepolymer slurry; The volume ratio of the siloxane-modified methacrylic acid to methyl methacrylate is 1~1.2:9; The preparation method of the siloxane-modified methacrylic acid is as follows: A condenser, stirrer, and three-necked flask are dried in an oven at 120°C for 2 hours, assembled while hot and protected with nitrogen gas, and γ-epoxypropoxypropyltrimethoxysilane and methacrylic acid are added. Under stirring conditions, triethylamine catalyst and hydroquinone polymerization inhibitor are added, and the reaction is carried out at 95~105°C for 4~8 hours. After the reaction is completed, the temperature is lowered to room temperature, deionized water is added to quench the catalyst, the reactants are washed with water and allowed to stand for separation, the organic phase is separated and dried to obtain siloxane-modified methacrylic acid. The molar ratio of γ-epoxypropoxypropyltrimethoxysilane to methacrylic acid is 1:1~1.

05. S2. Hydroxyl-terminated ether polysiloxane, isophorone diisocyanate and catalyst dibutyltin dilaurate are mixed and reacted with magnetic stirring at room temperature for 4-6 hours to obtain a macromolecular prepolymer. Then, the end-capping agent N-hydroxymethylacrylamide and the photoinitiator 2-hydroxy-2-methylphenylacetone are added to it, and stirring is continued at room temperature in the dark for 2 hours to obtain the coating slurry. S3. The prepolymer slurry is injected between two synchronously running annular steel belts, and the coating slurry is applied to the two annular steel belts at the same time. During the operation of the annular steel belts, the prepolymer slurry is continuously polymerized through a first polymerization zone and a second polymerization zone. After being kept warm in a heat preservation zone and cooled in a cooling zone, an acrylic sheet coated with the coating slurry is obtained. The acrylic sheet coated with the coating slurry is then cured with ultraviolet light to obtain a high-hardness acrylic sheet.

2. The method for preparing a continuously cast high-hardness acrylic sheet according to claim 1, characterized in that, In step S1, the n-butyl methacrylate accounts for 1 to 20% of the total volume of the methyl methacrylate and n-butyl methacrylate.

3. The method for preparing a continuously cast high-hardness acrylic sheet according to claim 1, characterized in that, The amount of triethylamine added is 0.6% of the total mass of γ-epoxypropoxypropyltrimethoxysilane and methacrylic acid, and the mass ratio of hydroquinone to triethylamine is 2:

15.

4. The method for preparing a continuously cast high-hardness acrylic sheet according to claim 1, characterized in that, The ultraviolet curing process specifically involves: initiating polymerization of the acrylic sheet coated with the coating slurry under 365nm ultraviolet light for 2-2.5 hours, then immersing it in an ethanol-water mixture for 30-45 minutes, followed by immersion in distilled water for 24 hours, and finally drying it at 60°C.

5. The method for preparing a continuously cast high-hardness acrylic sheet according to claim 1, characterized in that, The temperature of the first polymerization zone is 60~80℃, and the polymerization time is 5~1440min; the polymerization temperature of the second polymerization zone is 100~140℃, and the polymerization time is 5~1440min; the temperature of the heat preservation zone is 100~140℃, and the heat preservation time is 5~1440min.

6. The method for preparing a continuously cast high-hardness acrylic sheet according to claim 1, characterized in that, In step S2, the preparation method of the hydroxyl-terminated ether polysiloxane is as follows: hydrogen-containing silicone oil and allyl hydroxyethyl ether are mixed and stirred evenly, the temperature is raised to 50°C and Karstedt catalyst is added, and then the temperature is raised to 60~70°C and reacted for 3~4 hours. After the reaction is completed, the reaction is carried out by rotary evaporation under pressure of 10~50 mbar to obtain the hydroxyl-terminated ether polysiloxane.

7. The method for preparing a continuously cast high-hardness acrylic sheet according to claim 6, characterized in that, The hydrogen content of the hydrogen-terminated silicone oil is 0.11~0.13%, the molar ratio of the hydrogen-terminated silicone oil to the allyl hydroxyethyl ether is 1:2, and the amount of Karstedt catalyst added is 0.15~0.2% of the total mass of the hydrogen-terminated silicone oil and the allyl hydroxyethyl ether.

8. The method for preparing a continuously cast high-hardness acrylic sheet according to claim 1, characterized in that, In step S2, the molar ratio of the terminal hydroxyl ether polysiloxane, isophorone diisocyanate and N-hydroxymethylacrylamide is 1:1.5:1, the amount of photoinitiator added is 0.2% of the total mass of the terminal hydroxyl ether polysiloxane and isophorone diisocyanate, and the mass ratio of the catalyst to the photoinitiator is 0.1~0.3:

2.

9. The continuously cast high-hardness acrylic sheet prepared by the method of claim 1.

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