Preparation method of methyl methacrylate polymer

Abstract

The invention relates to a preparation method of a methyl methacrylate polymer, and belongs to the technical field of high polymer material preparation. The invention discloses a preparation method of methyl methacrylate. The preparation method comprises the following steps: (1) putting a monomer, a solvent, an initiator and a stabilizer into a reaction kettle, and stirring under the condition of introducing nitrogen; (2) then adding silsesquioxane for ultrasonic treatment; and (3) washing with methanol, carrying out vacuum drying, putting into an extruder together with an elastomer, extruding, granulating, and cooling to obtain the methyl methacrylate polymer with good heat resistance. The heat resistance is improved by introducing the alpha-methylstyrene chain segment, the glass transition temperature of the polymer is further improved by adding the semi-siloxane for modification, the thermal stability of the chain segment is improved by the initiator and the stabilizer, and the problem of chain opening and depolymerization caused by random shearing of the alpha-methylstyrene chain segment is inhibited by adding the elastomer.

Description

Technical Field

[0001] The present invention belongs to the technical field of polymer material preparation, and relates to a method for preparing methyl methacrylate polymer. Background Art

[0002] PMMA (methyl methacrylate polymer) is one of the polymers with the best light transmittance, and has excellent optical properties, chemical stability, processability, weather resistance, etc., and is widely used in the fields of aviation, architecture, decoration, optics, etc. However, the heat resistance of PMMA resin is poor, the glass transition temperature (Tg) is about 105 °C, the heat distortion temperature is only 85 °C, and the use temperature is below 80 °C. This shortcoming severely limits its application range. In order to expand its application range, aiming at the shortcoming of poor heat resistance of PMMA, domestic and foreign researchers have carried out a large number of heat resistance modification studies. Copolymerization, crosslinking and blending are common methods to improve the heat resistance of PMMA resin. Currently used monomers include cyclohexyl methacrylate, isobornyl methacrylate, maleic anhydride, N-phenyl maleimide, acrylic acid, methacrylic acid, acrylamide, methacrylamide, etc. to synthesize heat-resistant PMMA resin. By copolymerizing with these monomers, the Tg of PMMA resin can be increased by 5-30 °C. Although these copolymerization monomers can significantly improve the heat resistance of PMMA resin, they all have deficiencies. The prices of cyclohexyl methacrylate and isobornyl methacrylate are relatively high, maleic anhydride and N-phenyl maleimide will cause PMMA resin to turn yellow, and acrylic acid, methacrylic acid, acrylamide and methacrylamide will increase the water absorption of the resin.

[0003] Some studies have shown that α-methylstyrene is used as a copolymerization monomer to prepare PMMA resin with high heat resistance by radical polymerization method, and its Tg can be as high as 132.6 °C. However, due to the introduction of α-methylstyrene chain segments, random shearing occurs, which leads to open-chain depolymerization and reduces the thermal stability of PMMA resin. Therefore, on this basis, the present invention optimizes the problem of poor thermal stability of PMMA resin. Summary of the Invention

[0004] The present invention relates to a method for preparing methyl methacrylate polymer, belonging to the technical field of preparation of polymer materials. The disclosed preparation method of methyl methacrylate includes the following steps: (1) putting monomers, solvents, initiators, and stabilizers into a reaction kettle, and stirring under the condition of introducing nitrogen; (2) then adding semi-siloxane for ultrasonic treatment; (3) then washing with methanol, drying under vacuum, putting it together with an elastomer into an extruder for extrusion, granulating, and obtaining a methyl methacrylate polymer with good heat resistance after cooling. The invention improves the heat resistance by introducing α-methylstyrene segments, and further improves the glass transition temperature of the polymer by adding semi-siloxane for modification. The initiator and stabilizer improve the thermal stability of the segments, and the addition of the elastomer inhibits the problem of chain scission and depolymerization caused by the random shear of α-methylstyrene segments.

[0005] The object of the present invention can be achieved by the following technical solutions: A method for preparing methyl methacrylate polymer, the preparation method of the methyl methacrylate polymer includes the following steps: (1) Putting monomers, solvents, initiators, and stabilizers into a reaction kettle for heating, and stirring under the condition of introducing nitrogen; (2) Then adding semi-siloxane for ultrasonic treatment; (3) Then washing with methanol, drying under vacuum to form a solid, putting it together with an elastomer into an extruder for extrusion, granulating, and obtaining a methyl methacrylate polymer after cooling.

[0006] Further, in the step (1), the monomers are methyl methacrylate and α-methylstyrene, and the mass ratio between the two is 10:0.9 - 1.5, and the solvent is toluene.

[0007] Further, in the step (1), the initiator is dicumyl peroxide, and the stabilizer is pentaerythritol tetra[β-(3,5-di-tert-butyl,4-hydroxyphenyl)propionate].

[0008] Further, in the step (1), the mass ratio between the monomers, solvents, initiators, and stabilizers is 36 - 38:10:0.02 - 0.04:0.03 - 0.05, the heating temperature is 130 - 135 °C, and the stirring time and rotation speed are 8 - 10 h and 800 - 1000 r / min respectively.

[0009] Further, in the step (2), the mass ratio of semi-siloxane to monomers is 0.002 - 0.006:1, where the semi-siloxane is polypropyl hemisiloxane, and the temperature and time of the ultrasonic treatment are 60 - 80 °C and 1 - 2 h respectively.

[0010] Further, in step (3), the temperature and time of vacuum drying are 70 - 80 °C and 12 h respectively, and the mass ratio of the solid to the elastomer is 10:0.01 - 0.03, where the elastomer is one or more of polyurethane thermoplastic elastomers, polyolefin thermoplastic elastomers, and ethylene - vinyl acetate elastomers.

[0011] Further, in step (3), the extrusion temperature of the extruder is 280 - 320 °C, and the temperature and time of cooling are 0 - 3 °C and 5 - 8 min respectively.

[0012] Further, in step (3), the molecular weight of the methyl methacrylate polymer is 3 - 5×10 5 g / mol.

[0013] Advantages of the present invention: 1. The invention improves heat resistance by introducing α - methylstyrene segments, and further improves the glass transition temperature of the polymer by adding hemisiloxane for modification. In addition, the rapid cooling process weakens the random shear of α - methylstyrene segments in the material, while the initiator and stabilizer improve the thermal stability of the segments, and the addition of the elastomer inhibits the problem of chain opening and depolymerization caused by the random shear of α - methylstyrene segments. Specific embodiments

[0014] To further illustrate the technical means and effects adopted by the present invention to achieve the predetermined invention purpose, the following, in combination with embodiments, details the specific embodiments, structures, features, and their effects of the present invention as follows.

[0015] The polypropyl hemisiloxane involved in the embodiments and comparative examples of the present invention was purchased from Hubei Maidehao Biotechnology Co., Ltd.; the polyurethane thermoplastic elastomer was purchased from Dongguan Yingxiang Plastic Raw Materials Co., Ltd.; the polyolefin thermoplastic elastomer was purchased from Shanghai Hehongcheng Plastic Technology Co., Ltd.; and the ethylene - vinyl acetate elastomer was purchased from Suzhou Tiantao Plasticization Co., Ltd. Example 1

[0016] A preparation method of a methyl methacrylate polymer, the preparation method of the methyl methacrylate polymer comprises the following steps: (1) Put the monomer, solvent, initiator, and stabilizer into a reaction kettle, heat, and stir under the condition of introducing nitrogen; (2) Then add hemisiloxane and perform ultrasonic treatment; (3) Then wash with methanol, vacuum dry to form a solid, put it into an extruder together with the elastomer for extrusion, granulate, and obtain the methyl methacrylate polymer after cooling.

[0017] In step (1), the monomers are methyl methacrylate and α-methylstyrene, and the mass ratio between the two is 10:0.9. The solvent is toluene.

[0018] In step (1), the initiator is diisopropylbenzene peroxide, and the stabilizer is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0019] In step (1), the mass ratio between the monomers, solvent, initiator and stabilizer is 36:10:0.02:0.03. The heating temperature is 130°C, and the stirring time and speed are 8 h and 800 r / min respectively.

[0020] In step (2), the mass ratio of the hemi-siloxane to the monomers is 0.002:1. The hemi-siloxane is polypropyl hemi-silsesquioxane, and the temperature and time of the ultrasonic treatment are 60°C and 1 h respectively.

[0021] In step (3), the temperature and time of the vacuum drying are 70°C and 12 h respectively. The mass ratio of the solid to the elastomer is 10:0.01, and the elastomer is a polyurethane thermoplastic elastomer.

[0022] In step (3), the extrusion temperature of the extruder is 280°C, and the temperature and time of the cooling are 0°C and 5 min respectively.

[0023] In step (3), the molecular weight of the methyl methacrylate polymer is 3×10 5 g / mol. Example 2

[0024] A method for preparing a methyl methacrylate polymer, the method for preparing the methyl methacrylate polymer comprising the following steps: (1) Put the monomers, solvent, initiator and stabilizer into a reaction kettle, heat, and stir under the condition of introducing nitrogen; (2) Then add the hemi-siloxane and perform ultrasonic treatment; (3) Then wash with methanol, vacuum dry to form a solid, put it into an extruder together with the elastomer, extrude, granulate, and obtain the methyl methacrylate polymer after cooling.

[0025] In step (1), the monomers are methyl methacrylate and α-methylstyrene, and the mass ratio between the two is 10:1.2. The solvent is toluene.

[0026] In step (1), the initiator is diisopropylbenzene peroxide, and the stabilizer is pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate].

[0027] In step (1), the mass ratio between the monomer, the solvent, the initiator and the stabilizer is 37:10:0.03:0.04, the heating temperature is 133 °C, and the stirring time and speed are 9 h and 900 r / min respectively.

[0028] In step (2), the mass ratio of the hemi-siloxane to the monomer is 0.004:1, where the hemi-siloxane is polypropyl hemi-silsesquioxane, and the temperature and time of the ultrasonic treatment are 70 °C and 1.5 h respectively.

[0029] In step (3), the temperature and time of the vacuum drying are 75 °C and 12 h respectively, the mass ratio of the solid to the elastomer is 10:0.02, where the elastomer is a polyolefin thermoplastic elastomer.

[0030] In step (3), the extrusion temperature of the extruder is 300 °C, and the temperature and time of the cooling are 2 °C and 6 min respectively.

[0031] In step (3), the molecular weight of the polymethyl methacrylate is 4×10 5 g / mol. Example 3

[0032] A method for preparing a polymethyl methacrylate, the method for preparing the polymethyl methacrylate comprises the following steps: (1) Put the monomer, the solvent, the initiator and the stabilizer into a reaction kettle for heating, and stir under the condition of introducing nitrogen; (2) Then add the hemi-siloxane for ultrasonic treatment; (3) Then wash with methanol, vacuum dry to form a solid, put it into an extruder together with the elastomer for extrusion, granulate, and obtain the polymethyl methacrylate after cooling.

[0033] In step (1), the monomer is methyl methacrylate and α-methylstyrene, and the mass ratio between them is 10:1.5, and the solvent is toluene.

[0034] In step (1), the initiator is dicumyl peroxide, and the stabilizer is pentaerythritol tetrakis[β-(3,5-di-tert-butyl,4-hydroxyphenyl)propionate].

[0035] In step (1), the mass ratio between the monomer, the solvent, the initiator and the stabilizer is 38:10:0.04:0.05, the heating temperature is 135 °C, and the stirring time and speed are 10 h and 1000 r / min respectively.

[0036] In step (2), the mass ratio of the hemisiloxane to the monomer is 0.006:1, where the hemisiloxane is polypropyl hemisiloxane, and the temperature and time of the ultrasonic treatment are 80°C and 2 h, respectively.

[0037] In step (3), the temperature and time of the vacuum drying are 80°C and 12 h, respectively. The mass ratio of the solid to the elastomer is 10:0.03, where the elastomer is composed of a polyurethane thermoplastic elastomer, a polyolefin thermoplastic elastomer, and an ethylene-vinyl acetate elastomer with a mass ratio of 1:1:1.

[0038] In step (3), the extrusion temperature of the extruder is 320°C, and the temperature and time of the cooling are 3°C and 8 min, respectively.

[0039] In step (3), the molecular weight of the polymethyl methacrylate is 5×10 5 g / mol.

[0040] Comparative Example 1 Based on Example 2, a method for preparing a polymethyl methacrylate, the method for preparing the polymethyl methacrylate includes the following steps: (1) Put the monomer, solvent, initiator, and stabilizer into a reaction kettle, heat, and stir under the condition of introducing nitrogen; (2) Then add hemisiloxane for ultrasonic treatment; (3) Then wash with methanol, vacuum dry to form a solid, put it into an extruder together with the elastomer for extrusion, granulate, and obtain the polymethyl methacrylate after cooling.

[0041] In step (1), the monomer is methyl methacrylate and α-methylstyrene, and the mass ratio between them is 10:1.2. The solvent is toluene.

[0042] In step (1), the initiator is di-tert-butyl peroxide, and the stabilizer is pentaerythritol tetra[β-(3,5-di-tert-butyl,4-hydroxyphenyl)propionate].

[0043] In step (1), the mass ratio among the monomer, solvent, initiator, and stabilizer is 37:10:0.03:0.04. The heating temperature is 133°C, and the stirring time and rotation speed are 9 h and 900 r / min, respectively.

[0044] In step (2), the mass ratio of the hemisiloxane to the monomer is 0.004:1, where the hemisiloxane is polypropyl hemisiloxane, and the temperature and time of the ultrasonic treatment are 70°C and 1.5 h, respectively.

[0045] In step (3), the temperature and time of vacuum drying are 75°C and 12 h respectively, and the mass ratio of the solid to the elastomer is 10:0.02, where the elastomer is a polyolefin thermoplastic elastomer.

[0046] In step (3), the extrusion temperature of the extruder is 300°C, and the temperature and time of cooling are 2°C and 6 min respectively.

[0047] In step (3), the molecular weight of the polymethyl methacrylate polymer is 4×10 5 g / mol.

[0048] Comparative Example 2 Based on Example 2, a method for preparing a polymethyl methacrylate polymer, the method for preparing the polymethyl methacrylate polymer comprises the following steps: (1) Put the monomer, solvent, and initiator into a reaction kettle, heat, and stir under the condition of introducing nitrogen; (2) Then add hemisiloxane and perform ultrasonic treatment; (3) Then wash with methanol, vacuum dry to form a solid, put it into an extruder together with the elastomer for extrusion, granulate, and obtain the polymethyl methacrylate polymer after cooling.

[0049] In step (1), the monomer is methyl methacrylate and α-methylstyrene, and the mass ratio between the two is 10:1.2, and the solvent is toluene.

[0050] In step (1), the initiator is dicumyl peroxide, and the stabilizer is pentaerythritol tetrakis[β-(3,5-di-tert-butyl,4-hydroxyphenyl)propionate].

[0051] In step (1), the mass ratio among the monomer, solvent, and initiator is 37:10:0.03, the heating temperature is 133°C, and the stirring time and rotation speed are 9 h and 900 r / min respectively.

[0052] In step (2), the mass ratio of hemisiloxane to the monomer is 0.004:1, where the hemisiloxane is polypropyl hemisiloxane, and the temperature and time of the ultrasonic treatment are 70°C and 1.5 h respectively.

[0053] In step (3), the temperature and time of vacuum drying are 75°C and 12 h respectively, and the mass ratio of the solid to the elastomer is 10:0.02, where the elastomer is a polyolefin thermoplastic elastomer.

[0054] In step (3), the extrusion temperature of the extruder is 300°C, and the temperature and time of cooling are 2°C and 6 min respectively.

[0055] The molecular weight of the polymethyl methacrylate in step (3) is 4×10 5 g / mol.

[0056] Comparative Example 3 On the basis of Example 2, a method for preparing a polymethyl methacrylate polymer, the method for preparing the polymethyl methacrylate polymer comprises the following steps: (1) Put the monomer, solvent, initiator, and stabilizer into a reaction kettle, heat, and stir under the condition of introducing nitrogen; (2) Then wash with methanol, vacuum dry to form a solid, put it into an extruder together with an elastomer for extrusion, granulate, and obtain a polymethyl methacrylate polymer after cooling.

[0057] In step (1), the monomer is methyl methacrylate and α-methylstyrene, and the mass ratio between the two is 10:1.2. The solvent is toluene.

[0058] In step (1), the initiator is dicumyl peroxide, and the stabilizer is pentaerythritol tetra[β-(3,5-di-tert-butyl,4-hydroxyphenyl)propionate].

[0059] In step (1), the mass ratio between the monomer, solvent, initiator, and stabilizer is 37:10:0.03:0.04. The heating temperature is 133°C, and the stirring time and speed are 9 h and 900 r / min respectively.

[0060] In step (3), the temperature and time of vacuum drying are 75°C and 12 h respectively. The mass ratio of the solid to the elastomer is 10:0.02, and the elastomer is a polyolefin thermoplastic elastomer.

[0061] In step (3), the extrusion temperature of the extruder is 300°C, and the temperature and time of cooling are 2°C and 6 min respectively.

[0062] The molecular weight of the polymethyl methacrylate in step (3) is 4×10 5 g / mol.

[0063] Comparative Example 4 On the basis of Example 2, a method for preparing a polymethyl methacrylate polymer, the method for preparing the polymethyl methacrylate polymer comprises the following steps: (1) Put the monomer, solvent, initiator, and stabilizer into a reaction kettle, heat, and stir under the condition of introducing nitrogen; (2) Then add hemisiloxane for ultrasonic treatment; (3) Then, wash with methanol and dry under vacuum to form a solid. Put the solid together with the elastomer into an extruder for extrusion and granulation. After cooling, a methyl methacrylate polymer is obtained.

[0064] In step (1), the monomers are methyl methacrylate and α-methylstyrene, and the mass ratio between them is 10:1.2. The solvent is toluene.

[0065] In step (1), the initiator is dicumyl peroxide, and the stabilizer is pentaerythritol tetra[β-(3,5-di-tert-butyl,4-hydroxyphenyl)propionate].

[0066] In step (1), the mass ratio among the monomers, the solvent, the initiator, and the stabilizer is 37:10:0.03:0.04. The heating temperature is 133 °C, and the stirring time and speed are 9 h and 900 r / min, respectively.

[0067] In step (2), the mass ratio of the hemi-siloxane to the monomers is 0.004:1. The hemi-siloxane is polypropyl hemi-silsesquioxane. The temperature and time of the ultrasonic treatment are 70 °C and 1.5 h, respectively.

[0068] In step (3), the temperature and time of the vacuum drying are 75 °C and 12 h, respectively. The mass ratio of the solid to the elastomer is 10:0.02. The elastomer is a polyolefin thermoplastic elastomer.

[0069] In step (3), the extrusion temperature of the extruder is 300 °C, and the temperature and time of the cooling are 25 °C and 6 min, respectively.

[0070] The molecular weight of the methyl methacrylate polymer in step (3) is 4×10 5 g / mol.

[0071] Comparative Example 5 Based on Example 2, a method for preparing a methyl methacrylate polymer, the method for preparing the methyl methacrylate polymer includes the following steps: (1) Put the monomers, the solvent, the initiator, and the stabilizer into a reaction kettle, heat, and stir under the condition of introducing nitrogen; (2) Then, add the hemi-siloxane and perform ultrasonic treatment; (3) Then, wash with methanol, dry under vacuum to form a solid, put it into an extruder for extrusion, granulate, and after cooling, obtain a methyl methacrylate polymer.

[0072] In step (1), the monomers are methyl methacrylate and α-methylstyrene, and the mass ratio between them is 10:1.2. The solvent is toluene.

[0073] In step (1), the initiator is dicumyl peroxide and the stabilizer is pentaerythritol tetrakis [β-(3,5-di-tert-butyl-4-hydroxyphenyl) propionate].

[0074] In step (1), the mass ratio of the monomer, solvent, initiator and stabilizer is 37:10:0.03:0.04. The heating temperature is 133 °C, and the stirring time and speed are 9 h and 900 r / min, respectively.

[0075] In step (2), the mass ratio of the hemi-siloxane to the monomer is 0.004:1. The hemi-siloxane is polypropyl hemi-silsesquioxane. The temperature and time of the ultrasonic treatment are 70 °C and 1.5 h, respectively.

[0076] In step (3), the temperature and time of the vacuum drying are 75 °C and 12 h, respectively.

[0077] In step (3), the extrusion temperature of the extruder is 300 °C. The temperature and time of the cooling are 2 °C and 6 min, respectively.

[0078] In step (3), the molecular weight of the polymethyl methacrylate is 4×10 5 g / mol.

[0079] Performance Test Taking Examples 1-3 and Comparative Examples 1-5 as samples, the glass transition temperature Tg of the polymer was measured using a differential scanning calorimeter (DSC8500). At the same time, for the samples of Comparative Example 1, Comparative Example 2, and Comparative Examples 4-5, a thermogravimetric analyzer (TG), Q500, TA Instruments, USA was used to measure the mass retention rate at 300 °C. In addition, the light transmittance of the samples was measured according to GB / T 2410. The test results are shown in Table 1.

[0080] Table 1 Test Results

[0081] As can be seen from Table 1, the glass transition temperatures of Examples 1-3 and Comparative Examples 1-5 are greater than 132.6 °C except for Comparative Example 3. The mass retention rates of Examples 1-3 are greater than those of the comparative examples (i.e., the thermal stability of the examples is better than that of the comparative examples). At the same time, it can be seen that the light transmittance of the examples and the comparative examples is not much different, and the introduction of semi-siloxane, initiator, and stabilizer does not affect the light transmittance of the specimen; in Comparative Example 1, the dicumyl peroxide initiator was replaced. Since dicumyl peroxide has a longer half-life, the occurrence of side reactions is reduced, thereby improving the thermal stability; the absence of a stabilizer in Comparative Example 2 makes the segment stability worse and affects the thermal stability; in Comparative Example 3, no semi-siloxane modification was added, resulting in a decrease in heat resistance; in Comparative Example 4, the cooling temperature was increased, the cooling rate of the segments was reduced, and the random shear could not be weakened, resulting in poor thermal stability; in Comparative Example 5, no elastomer was added, and the shear energy could not be dispersed, causing the segments to be directly impacted and broken.

[0082] The above are only the preferred embodiments of the present invention, and do not impose any formal limitations on the present invention. Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Any person skilled in the art can make some changes or modifications to equivalent embodiments by using the above-disclosed technical content without departing from the scope of the technical solution of the present invention. However, as long as it does not depart from the content of the technical solution of the present invention, any brief modifications, equivalent changes, and modifications made to the above embodiments based on the technical essence of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a methyl methacrylate polymer, characterized in that, The preparation method of the methyl methacrylate polymer comprises the following steps: (1) Put the monomer, solvent, initiator, and stabilizer into a reaction kettle, heat it, and stir it under the condition of introducing nitrogen; (2) Then add the hemisiloxane and perform ultrasonic treatment; (3) Then wash with methanol, vacuum dry to form a solid, put it into an extruder together with the elastomer for extrusion, granulate, and obtain the methyl methacrylate polymer after cooling.

2. The preparation method of a methyl methacrylate polymer according to claim 1, wherein In the step (1), the monomer is methyl methacrylate and α-methylstyrene, and the mass ratio between the two is 10:0.9 - 1.

5. The solvent is toluene.

3. The preparation method of a methyl methacrylate polymer according to claim 1, characterized in that, In the step (1), the initiator is dicumyl peroxide, and the stabilizer is pentaerythritol tetra[β-(3,5-di-tert-butyl,4-hydroxyphenyl)propionate].

4. The preparation method of a methyl methacrylate polymer according to claim 1, characterized in that, In the step (1), the mass ratio between the monomer, solvent, initiator, and stabilizer is 36 - 38:10:0.02 - 0.04:0.03 - 0.

05. The heating temperature is 130 - 135 °C, and the stirring time and speed are 8 - 10 h and 800 - 1000 r / min respectively.

5. The preparation method of a methyl methacrylate polymer according to claim 1, wherein In the step (2), the mass ratio of the hemisiloxane to the monomer is 0.002 - 0.006:

1. The hemisiloxane is polypropyl hemisiloxane. The temperature and time of the ultrasonic treatment are 60 - 80 °C and 1 - 2 h respectively.

6. The preparation method of a methyl methacrylate polymer according to claim 1, characterized in that, In the step (3), the temperature and time of the vacuum drying are 70 - 80 °C and 12 h respectively. The mass ratio of the solid to the elastomer is 10:0.01 - 0.

03. The elastomer is one or more of polyurethane thermoplastic elastomer, polyolefin thermoplastic elastomer, and ethylene-vinyl acetate elastomer.

7. A method for preparing a methyl methacrylate polymer according to claim 1, characterized in that, In the step (3), the extrusion temperature of the extruder is 280 - 320 °C, and the temperature and time of the cooling are 0 - 3 °C and 5 - 8 min respectively.

8. The preparation method of a methyl methacrylate polymer according to claim 1, characterized in that, The molecular weight of the polymethyl methacrylate in step (3) is 3 - 5×10 5 g / mol.

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