Polynorbornene imide film as well as preparation method and application thereof
By introducing monomers with improved side chain structure into polynorbornenomide-based materials and preparing all-organic polymers through open ring metathesis polymerization, the problem of poor insulation performance of polynorbornenomide-based materials at high temperatures is solved, and high insulation performance under extreme conditions is achieved, and winding insulation materials are suitable for high-performance electrical equipment.
Patent Information
- Application Number
- CN202510297153.5
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-03-13
- Publication Date
- 2025-06-17
AI Technical Summary
The existing polynorbornenomide-based materials have poor insulation performance at high temperatures, making it difficult to meet the needs of high-performance electrical equipment under extreme working conditions.
By amidating the norbornene diacid anhydride and aniline derivative under the action of a catalyst, a polynorbornene imide monomer with improved side chain structure was prepared, and an all-organic polymer was prepared by ring-opening metathesis polymerization reaction method to improve its insulation performance.
The prepared polynorbornenomide film exhibits good insulation performance at room temperature and 150°C, has low leakage current density and dielectric loss, and is suitable for the preparation of electrical insulating devices.
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Figure CN120157609A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to a poly(norborneneimide) film, a preparation method thereof and an application thereof, belonging to the technical field of electrical insulation materials and their preparation. Background Art
[0002] Winding insulation is an important part of electrical equipment. Especially in the manufacture of equipment such as motors and power transformers, winding insulation is directly related to the electrical performance and safety of the equipment. With the continuous increase of the operating load and voltage of electrical equipment, the performance requirements for winding insulation materials are also increasing day by day. The existing winding insulation materials mainly include traditional polyimides, epoxy resins, etc. These materials meet the basic needs of electrical equipment to a certain extent. However, with the gradual increase of requirements for the long-term stability and heat resistance of electrical equipment, the performance of existing winding insulation materials has been difficult to meet the needs of high-performance electrical equipment. Especially under high temperature, high humidity and extreme working conditions, problems such as poor heat resistance and insulation performance decline often occur in winding insulation materials.
[0003] Poly(norborneneimide)-based materials have gradually become a research hotspot for new winding insulation materials due to their excellent properties such as high temperature resistance and high field resistance. However, due to the softening and aging phenomena at high temperature, the electrical performance of poly(norborneneimide)-based materials will gradually decline during long-term use. Therefore, it is very necessary to further improve the insulation performance of poly(norborneneimide) under high temperature, high pressure and other extreme working conditions to provide a more excellent material choice for the winding insulation of electrical equipment. Summary of the Invention
[0004] Aiming at the problem of poor insulation performance at high temperature existing in the existing poly(norborneneimide)-based materials, the present invention provides a poly(norborneneimide) film, a preparation method thereof and an application thereof.
[0005] The technical solution of the present invention:
[0006] One of the purposes of the present invention is to provide a preparation method of a monomer for preparing a poly(norborneneimide) film, and the method includes the following steps:
[0007] (1) Dissolve norbornene dianhydride in an acetic acid solution to obtain solution A;
[0008] (2) Add an aniline derivative to solution A and stir evenly to obtain solution B;
[0009] (3) Add a catalyst to solution B and stir at 105 - 115 °C for 20 - 24 h to obtain solution C;
[0010] (4) After solution C is cooled to room temperature, add deionized water, carry out vacuum filtration to obtain a white solid, wash it and then recrystallize it with absolute ethanol to obtain the monomer.
[0011] Further limitation: the aniline derivative is 4-methyl-3-trifluoromethylaniline, 3-fluoro-4-methylaniline, 3-chloro-4-methylaniline or 3-bromo-4-methylaniline.
[0012] Further limitation: the molar ratio of norbornene dianhydride to the aniline derivative is 1:(1.02 - 1.08).
[0013] Further limitation: the catalyst is 4-dimethylaminopyridine, and the molar ratio of norbornene dianhydride to the catalyst is (1.6 - 1.7):1.
[0014] Further limitation: the volume ratio of glacial acetic acid to deionized water is 1:(3 - 4).
[0015] The second object of the present invention is to provide a monomer prepared by the above method.
[0016] The third object of the present invention is to provide an application of the above monomer.
[0017] Further limitation: the above monomer is used to prepare a polymer for preparing a poly(norbornene imide) film.
[0018] The fourth object of the present invention is to provide a method for preparing a polymer of poly(norbornene imide) film using the above monomer, and the method includes the following steps:
[0019] (1) Under a dry nitrogen environment, dissolve the monomer described in claim 5 in an ultradry dichloromethane solution to obtain solution D;
[0020] (2) Under a dry nitrogen environment, dissolve the Grubbs 2nd generation catalyst in an ultradry dichloromethane solution to obtain solution E;
[0021] (3) Under a dry nitrogen environment, mix solution D and solution E, stir and react at room temperature for 6 - 8 h, add the terminator vinyl ethyl ether and then continue to stir for 30 - 40 min;
[0022] (4) Drop the reacted solution into a methanol solution to obtain a solid product, use methanol as the solution, perform Soxhlet extraction on the solid product for 45 - 50 h, and finally vacuum dry at 60 °C for 22 - 26 h to obtain the polymer.
[0023] Further limitation: the mass-volume ratio of the monomer, the Grubbs 2nd generation catalyst and the terminator vinyl ethyl ether is 2 g:(18 - 22) mg:(2 - 3) mL.
[0024] Further limitation: the mass-volume ratio of the monomer to dichloromethane in solution D is 2 g:20 mL.
[0025] Further limitation: the mass-volume ratio of Grubbs 2nd generation catalyst to ultra-dry dichloromethane in solution E is (18 - 22) mg : 2 mL.
[0026] The fifth object of the present invention is to provide a polymer prepared by the above method.
[0027] The sixth object of the present invention is to provide an application of the above polymer.
[0028] Further limitation: the above polymer is used for preparing a poly(norborneneimide) film.
[0029] The seventh object of the present invention is to provide a method for preparing a poly(norborneneimide) film. The method is as follows: dissolve the polymer in an ultra-dry dichloromethane solution, then form a film on a glass plate by solution casting method to obtain a wet film, dry the wet film to obtain a dry film, and perform vacuum drying treatment on the dry film to obtain a poly(norborneneimide) film.
[0030] Further limitation: the mass fraction of the polymer in the casting solution is 3 - 7%.
[0031] Further limitation: the drying treatment temperature is 55 - 60 °C and the time is 2 - 5 h.
[0032] Further limitation: the vacuum drying treatment conditions are: under vacuum conditions at 55 - 65 °C, perform drying treatment for 22 - 24 h.
[0033] Further limitation: the thickness of the obtained poly(norborneneimide) film is 5 - 15 μm.
[0034] The eighth object of the present invention is to provide a poly(norborneneimide) film prepared by the above method.
[0035] The ninth object of the present invention is to provide an application of the above poly(norborneneimide) film, specifically as an insulating medium for the preparation of electrical insulation devices.
[0036] Further limitation: the electrical insulation devices include smart power grids, new energy vehicles, and AC / DC transmission networks.
[0037] Beneficial effects:
[0038] The present invention uses norbornene dianhydride and aniline derivatives to obtain monomers through amidation reaction under the action of a catalyst. The monomers are used to prepare all-organic poly(norbornene imide) - based insulating polymers by ring-opening metathesis polymerization (ROMP) reaction. By changing the side-chain structure of poly(norbornene imide), methyl (-CH3) groups with high polarization characteristics are introduced at the para-position of the benzene ring to improve the dielectric properties of the insulating medium, and strongly electronegative (-CF3, -F, -Cl, and -Br) groups are introduced at the ortho- and para-positions of the benzene ring to improve the insulation performance of the poly(norbornene imide) - based insulating medium, thereby improving the dielectric properties and breakdown field strength of the insulating medium, and preparing a dielectric material for winding insulation with good insulation performance. Compared with the prior art, this polymer has the following advantages:
[0039] (1) The poly(norbornene imide) - based insulating medium prepared in the present invention has good insulation performance (~801.1 MV / m, 711.2 MV / m) at room temperature and 150 °C, has a low leakage current density and a low dielectric loss, and is suitable for the preparation of electrical insulation devices.
[0040] (2) The synthesis process flow of the poly(norbornene imide) - based insulating medium with high insulation characteristics provided by the present invention is simple, the obtained products are uniform, stable, highly reproducible, environmentally friendly and pollution-free, the equipment is inexpensive, suitable for large-scale production, and has very broad research value and application prospects. Description of the Drawings
[0041] Figure 1 is the synthesis process of monomers CH3-NI, CF3-NI, F-NI, Cl-NI, and Br-NI;
[0042] Figure 2 is the synthesis process of polymers CF3-PNI, CF3-PNI, F-PNI, Cl-PNI, and Br-PNI;
[0043] Figure 3 is the X-ray diffraction comparison diagram of the poly(norbornene imide) - based thin films prepared in Examples 1 to 4 and Comparative Example 1;
[0044] Figure 4 is the Fourier transform infrared spectroscopy comparison diagram of the poly(norbornene imide) - based thin films prepared in Examples 1 to 4 and Comparative Example 1;
[0045] Figure 5 is the Weibull distribution diagram of the room-temperature breakdown field strength of the poly(norbornene imide) - based thin films prepared in Examples 1 to 4 and Comparative Example 1;
[0046] Figure 6 is the Weibull distribution diagram of the 150 °C breakdown field strength of the poly(norbornene imide) - based thin films prepared in Examples 1 to 4 and Comparative Example 1;
[0047] Figure 7 Graph for comparing the room temperature dielectric properties of the poly(norbornene imide) films prepared in Examples 1-4 and Comparative Example 1;
[0048] Figure 8 Graph for comparing the leakage current density at 150 °C of the poly(norbornene imide) films prepared in Examples 1-4 and Comparative Example 1. Detailed implementation manners
[0049] To make the above objects, features and advantages of the present invention more obvious and understandable, the following will describe the detailed implementation manners of the present invention in conjunction with the embodiments of the specification.
[0050] In the following description, many specific details are set forth to fully understand the present invention. However, the present invention can also be implemented in other ways different from those described herein. Those skilled in the art can make similar generalizations without departing from the connotation of the present invention. Therefore, the present invention is not limited by the specific embodiments disclosed below.
[0051] Secondly, the so-called "one embodiment" or "embodiment" herein refers to a specific feature, structure or characteristic that can be included in at least one implementation manner of the present invention. The "in one embodiment" that appears in different places in this specification does not all refer to the same embodiment, nor is it a separate or selectively exclusive embodiment from other embodiments.
[0052] The experimental methods used in the following embodiments are all conventional methods unless otherwise specified. The materials, reagents, methods and instruments used, unless otherwise specified, are all conventional materials, reagents, methods and instruments in the art. Those skilled in the art can obtain them through commercial channels, and the purity of the solid and liquid reagents used is analytical pure.
[0053] Example 1
[0054] Step 1: Take 4.97 g of norbornene dianhydride and dissolve it in 50 ml of glacial acetic acid solution at room temperature to obtain solution A.
[0055] Step 2: Add 4-methyl-3-trifluoromethylaniline to solution A to obtain solution B. Among them, the molar ratio of norbornene dianhydride to 4-methyl-3-trifluoromethylaniline is 1:1.08.
[0056] Step 3: Add the catalyst 4-dimethylaminopyridine to solution B to obtain solution C. Among them, the molar ratio of norbornene dianhydride to 4-dimethylaminopyridine is 1.6:1.
[0057] Step 4: Stir solution C at 110 °C for 24 h. After the solution is cooled to room temperature, add 150 ml of deionized water thereto, stir, and perform suction filtration to obtain a white solid.
[0058] Step 5: Wash the white solid obtained in Step 4 with a large amount of deionized water, and then recrystallize it with absolute ethanol to obtain the final product monomer CF3-NI. The synthesis process is as Figure 1 shown in R = CF3 in
[0059] Step 6: Weigh 2 g of CF3-NI monomer, dissolve it in 20 ml of ultradry dichloromethane solution under a dry nitrogen environment, and stir at room temperature to obtain solution D.
[0060] Step 7: Weigh 22 mg of Grubbs 2nd generation catalyst, dissolve it in 2 ml of ultradry dichloromethane solution under a dry nitrogen environment, and stir at room temperature to obtain solution E.
[0061] Step 8: Mix solution D and solution E, stir and react at room temperature for 6 h under a dry nitrogen environment, then add 3 ml of terminator vinyl ethyl ether to the mixed solution and continue stirring for 30 min to stop the reaction.
[0062] Step 9: Drop the solution after the reaction is stopped into a methanol solution to obtain a solid product. Then, use methanol as the solution, perform Soxhlet extraction on the obtained solid product for 48 h, and then dry it in vacuum at 60 °C for 12 h to obtain the polymer CF3-PNI. The synthesis process is as Figure 2 shown in R = CF3 in
[0063] Step 10: Take the polymer CF3-PNI and dissolve it in an ultradry dichloromethane solution to obtain a polymer solution with a mass fraction of 6%.
[0064] Step 11: Uniformly coat the polymer solution on a glass plate by the solution casting method to obtain a wet film. Dry it at 60 °C for 2 h to obtain a dry film, and then dry the dry film in vacuum at 60 °C for 24 h to obtain a CF3-PNI polymer film with a thickness of 10 μm, named CF3.
[0065] Example 2
[0066] Step 1: Take 4.97 g of norbornene dianhydride and dissolve it in 50 ml of glacial acetic acid solution at room temperature to obtain solution A.
[0067] Step 2: Add 3-fluoro-4-methylaniline to solution A to obtain solution B. Among them, the molar ratio of norbornene dianhydride to 3-fluoro-4-methylaniline is 1:1.08.
[0068] Step 3: Add a predetermined mass of the catalyst 4-dimethylaminopyridine to Solution B to obtain Solution C. Among them, the molar ratio of norbornene dianhydride to 4-dimethylaminopyridine is 1.6:1.
[0069] Step 4: Stir Solution C at 110 °C for 24 h. After the solution is cooled to room temperature, add 150 ml of deionized water thereto, stir, filter, and obtain a white solid.
[0070] Step 5: Wash the white solid obtained in Step 4 with a large amount of deionized water, and then recrystallize it with absolute ethanol to obtain the final product monomer F-NI. The synthesis process is as Figure 1 shown in R = F in
[0071] Step 6: Weigh 2 g of F-NI monomer, dissolve it in 20 ml of ultra-dry dichloromethane solution under a dry nitrogen environment, and stir at room temperature to obtain Solution D.
[0072] Step 7: Weigh 20 mg of Grubbs 2nd generation catalyst, dissolve it in 2 ml of ultra-dry dichloromethane solution under a dry nitrogen environment, and stir at room temperature to obtain Solution E.
[0073] Step 8: Mix Solution D and Solution E, stir and react at room temperature under a dry nitrogen environment for 6 h, then add 2 ml of the terminator vinyl ethyl ether to the mixed solution and continue to stir for 30 min to stop the reaction.
[0074] Step 9: Drop the solution after the reaction is stopped into a methanol solution to obtain a solid product, then use methanol as the solution, subject the obtained solid product to Soxhlet extraction for 48 h, and then dry it in vacuo at 60 °C for 12 h to obtain the polymer F-PNI. The synthesis process is as Figure 2 shown in R = F in
[0075] Step 10: Dissolve the polymer F-PNI in an ultra-dry dichloromethane solution to obtain a polymer solution with a mass fraction of 6%.
[0076] Step 11: Uniformly coat the ultra-dry dichloromethane solution of the polymer F-PNI on a glass plate by the solution casting method to obtain a wet film, dry it at 60 °C for 2 h to obtain a dry film, and then dry the dry film in vacuo at 60 °C for 24 h to obtain an F-PNI polymer film with a thickness of 10 μm, named F.
[0077] Example 3
[0078] Step 1: Take 4.97 g of norbornene dianhydride and dissolve it at room temperature in 50 ml of glacial acetic acid solution to obtain Solution A.
[0079] Step 2: Add 3-chloro-4-methylaniline to Solution A to obtain Solution B. Among them, the molar ratio of norbornene dianhydride to 3-fluoro-4-methylaniline is 1:1.08.
[0080] Step 3: Add a predetermined mass of the catalyst 4-dimethylaminopyridine to Solution B to obtain Solution C. Among them, the molar ratio of norbornene dicarboxylic anhydride to 4-dimethylaminopyridine is 1.6:1.
[0081] Step 4: Stir Solution C at 110 °C for 20 - 24 h. After the solution is cooled to room temperature, add 150 ml of deionized water, stir, and perform suction filtration to obtain a white solid.
[0082] Step 5: Wash the white solid obtained in Step 4 with a large amount of deionized water, and then recrystallize it with absolute ethanol to obtain the final product monomer Cl-NI. The synthesis process is as Figure 1 shown in which R = Cl.
[0083] Step 6: Weigh 2 g of the Cl-NI monomer, dissolve it in 20 ml of ultra-dry dichloromethane solution under a dry nitrogen environment, and stir at room temperature to obtain Solution D.
[0084] Step 7: Weigh 18 mg of the Grubbs 2nd generation catalyst, dissolve it in 2 ml of ultra-dry dichloromethane solution under a dry nitrogen environment, and stir at room temperature to obtain Solution E.
[0085] Step 8: Mix Solution D and Solution E, stir and react at room temperature for 6 h under a dry nitrogen environment. Then, add 2 ml of the terminator vinyl ethyl ether to the mixed solution and continue stirring for 30 min to stop the reaction.
[0086] Step 9: Drop the solution after the reaction is stopped into a methanol solution to obtain a solid product. Then, use methanol as the solution, perform Soxhlet extraction on the obtained solid product for 48 h, and then dry it in vacuo at 60 °C for 12 h to obtain the polymer Cl-PNI. The synthesis process is as Figure 2 shown in which R = Cl.
[0087] Step 10: Dissolve the polymer Cl-PNI in an ultra-dry dichloromethane solution to obtain a polymer solution with a mass fraction of 6%.
[0088] Step 11: Uniformly coat the ultra-dry dichloromethane solution of the polymer Cl-PNI on a glass plate by the solution casting method to obtain a wet film. Dry it at 60 °C for 2 h to obtain a dry film, and then dry the dry film in vacuo at 60 °C for 24 h to obtain a Cl-PNI polymer film with a thickness of 10 μm, named Cl.
[0089] Example 4
[0090] Step 1: Take 4.97 g of norbornene dicarboxylic anhydride and dissolve it at room temperature in 50 ml of glacial acetic acid solution to obtain Solution A.
[0091] Step 2: Add 3-bromo-4-methylaniline to Solution A to obtain Solution B. Among them, the molar ratio of norbornene dianhydride to 3-bromo-4-methylaniline is 1:1.08.
[0092] Step 3: Add a predetermined mass of the catalyst 4-dimethylaminopyridine to Solution B to obtain Solution C. Among them, the molar ratio of norbornene dianhydride to 4-dimethylaminopyridine is 1.6:1.
[0093] Step 4: Stir Solution C at 110 °C for 24 h. After the solution is cooled to room temperature, add 150 ml of deionized water, stir, and filter to obtain a white solid.
[0094] Step 5: Wash the white solid obtained in Step 4 with a large amount of deionized water, and then recrystallize it with absolute ethanol to obtain the final product monomer Br-NI. The synthesis process is as Figure 1 shown in R = Br.
[0095] Step 6: Weigh 2 g of the Br-NI monomer, dissolve it in 20 ml of ultra-dry dichloromethane solution under a dry nitrogen environment, and stir at room temperature to obtain Solution D.
[0096] Step 7: Weigh 18 mg of the Grubbs 2nd generation catalyst, dissolve it in 2 ml of ultra-dry dichloromethane solution under a dry nitrogen environment, and stir at room temperature to obtain Solution E.
[0097] Step 8: Mix Solution D and Solution E, stir and react at room temperature for 6 h under a dry nitrogen environment. Then, add 2 ml of the terminator vinyl ethyl ether to the mixed solution and continue stirring for 30 min to stop the reaction.
[0098] Step 9: Drop the solution after the reaction is stopped into a methanol solution to obtain a solid product. Then, use methanol as the solution, subject the obtained solid product to Soxhlet extraction for 48 h, and then dry it in a vacuum at 60 °C for 12 h to obtain the polymer Br-PNI. The synthesis process is as Figure 2 shown in R = Br.
[0099] Step 10: Dissolve the polymer Br-PNI in an ultra-dry dichloromethane solution to obtain a polymer solution with a mass fraction of 6%.
[0100] Step 11: Uniformly coat the ultra-dry dichloromethane solution of the polymer Br-PNI on a glass plate by the solution casting method to obtain a wet film. Dry it at 60 °C for 2 h to obtain a dry film, and then dry the dry film in a vacuum at 60 °C for 24 h to obtain a Br-PNI polymer film with a thickness of 10 μm, named Br.
[0101] Comparative Example 1
[0102] Step 1: Dissolve 4.97 g of norbornene dianhydride in 50 ml of glacial acetic acid solution at room temperature to obtain solution A.
[0103] Step 2: Add p-toluidine to solution A to obtain solution B. Among them, the molar ratio of norbornene dianhydride to 3-fluoro-4-methylaniline is 1:1.08.
[0104] Step 3: Add a predetermined mass of the catalyst 4-dimethylaminopyridine to solution B to obtain solution C. Among them, the molar ratio of norbornene dianhydride to 4-dimethylaminopyridine is 1.6:1.
[0105] Step 4: Stir solution C at 110 °C for 24 h. After the solution is cooled to room temperature, add 150 ml of deionized water, stir, and filter to obtain a white solid.
[0106] Step 5: Wash the white solid obtained in Step 4 with a large amount of deionized water, and then recrystallize it with absolute ethanol to obtain the final product monomer CH3-NI. The synthesis process is as Figure 1 shown in R = CH3.
[0107] Step 6: Weigh 2 g of CH3-NI monomer, dissolve it in 20 ml of ultra-dry dichloromethane solution under a dry nitrogen environment, and stir at room temperature to obtain solution D.
[0108] Step 7: Weigh 18 mg of Grubbs 2nd generation catalyst, dissolve it in 2 ml of ultra-dry dichloromethane solution under a dry nitrogen environment, and stir at room temperature to obtain solution E.
[0109] Step 8: Mix solution D and solution E, stir and react at room temperature for 6 h under a dry nitrogen environment. Then, add 2 ml of the terminator vinyl ethyl ether to the mixed solution and continue to stir for 30 min to stop the reaction.
[0110] Step 9: Drop the solution after the reaction is stopped into a methanol solution to obtain a solid product. Then, use methanol as the solution, subject the obtained solid product to Soxhlet extraction for 48 h, and then dry it in a vacuum at 60 °C for 12 h to obtain the polymer CH3-PNI. The synthesis process is as Figure 2 shown in R = CH3.
[0111] Step 10: Dissolve the polymer CH3-PNI in an ultra-dry dichloromethane solution to obtain a polymer solution with a mass fraction of 6%.
[0112] Step 11: Uniformly coat the ultra-dry dichloromethane solution of the polymer CH3-PNI on a glass plate by the solution casting method to obtain a wet film. Dry it at 60 °C for 2 h to obtain a dry film, and then dry the dry film in a vacuum at 60 °C for 24 h to obtain a CH3-PNI polymer film with a thickness of 10 μm, named CH3.
[0113] Effect Example
[0114] (1) Figure 3 Figure for X-ray diffraction comparison of poly(norbornene imide)-based films with high insulation properties in Examples 1 to 4 and Comparative Example 1. It can be seen from the figure that there are no obvious diffraction peaks in all film samples, and there are relatively large diffuse peaks between 10 - 40°, indicating that the films are in an uncrystallized state.
[0115] (2) Figure 4 Figure for Fourier transform infrared spectroscopy comparison of poly(norbornene imide)-based films with high insulation properties in Examples 1 to 4 and Comparative Example 1. It can be seen from the figure that the symmetric stretching vibration absorption peak and asymmetric vibration absorption peak of C=O in the imide group at around 1700 cm -1 and around 1780 cm -1 , the stretching vibration absorption peak of C-N in the imide group at around 1380 cm -1 , the bending vibration absorption peak of C-H at around 850 cm -1 , the absorption peak of C=CH bond generated during the polymerization process at around 570 cm -1 , the stretching vibration absorption peak of C-F with meta-substituted CF3 at around 1130 cm -1 , the stretching vibration absorption peak of C-F with meta-substituted F at around 1115 cm -1 , the stretching vibration absorption peak of C-Cl with meta-substituted Cl at around 600 cm -1 , and the stretching vibration absorption peak of C-Br with meta-substituted Br at around 595 cm -1 . The above results all prove the successful synthesis of the polymer film, that is, the side chain structure has a methyl group (CH3) at the para position of the benzene ring and an R group at the ortho position.
[0116] (3) Figure 5 Figure for Weibull distribution of breakdown field strength at room temperature of poly(norbornene imide)-based films with high insulation properties in Examples 1 to 4 and Comparative Example 1. It can be seen from the figure that increasing the electronegative group at the meta position of the benzene ring helps to improve the breakdown field strength of the film. Among them, when the meta-substitution is a Cl group, the film obtains the most excellent breakdown field strength of 801.1 MV / m.
[0117] (4) Figure 6 Figure for Weibull distribution of breakdown field strength at 150 °C of poly(norbornene imide)-based films with high insulation properties in Examples 1 to 4 and Comparative Example 1. It can be seen from the figure that as the temperature increases, the insulation performance of the film decreases, but still remains at a relatively high level. Among them, when the meta-substitution is a Cl group, the film obtains the most excellent breakdown field strength of 711.2 MV / m.
[0118] (5)Figure 7 It is a comparison chart of the room-temperature dielectric properties of the poly(norbornene imide)-based films with high insulation properties in Examples 1 to 4 and Comparative Example 1. It can be seen from the chart that, different from the previous introduction of electronegative groups, adding electronegative groups between the meta-positions of the benzene rings in the poly(norbornene imide) group helps to increase the relative dielectric constant of the film. The reason is that the introduction of electronegative groups in the side chain enhances the asymmetry of the benzene ring, resulting in a change in the electron cloud distribution of the benzene ring. When an external electric field acts on the polymer film, the degree of molecular polarization is higher, leading to a relative increase in the dielectric constant of the film. At the same time, the dielectric losses of the poly(norbornene imide)-based films all remain at a relatively low level.
[0119] (6) Figure 8 It is a comparison chart of the leakage current density at 150 °C of the poly(norbornene imide)-based films with high insulation properties in Examples 1 to 4 and Comparative Example 1. It can be seen from the chart that the enhanced asymmetry of the benzene ring caused by the introduction of electronegative groups in the side chain leads to an increase in the leakage current density of the film. However, when the meta-position substitution is a Cl group, the increase in the leakage current density is relatively low.
[0120] Although the present invention has been disclosed above with preferred embodiments, it is not intended to limit the present invention. Anyone familiar with this technology can make various modifications and refinements without departing from the spirit and scope of the present invention. Therefore, the protection scope of the present invention should be defined by the claims.
Claims
1. A method for preparing a monomer for preparing a polynorbornene imide film, characterized in that: include: (1) dissolving nadic anhydride in glacial acetic acid solution to obtain solution A; (2) adding the aniline derivative to solution A and stirring evenly to obtain solution B; (3) adding the catalyst to solution B and stirring at 105-115° C. for 20-24 h to obtain solution C; (4) After solution C is cooled to room temperature, deionized water is added and vacuum filtered to obtain a white solid, which is then washed and recrystallized using anhydrous ethanol to obtain a monomer.
2. The preparation method according to claim 1, characterized in that: The aniline derivative is 4-methyl-3-trifluoromethylaniline, 3-fluoro-4-methylaniline, 3-chloro-4-methylaniline or 3-bromo-4-methylaniline.
3. The preparation method according to claim 1, characterized in that: The molar ratio of nadic anhydride to aniline derivative is 1:(1.02-1.08).
4. The preparation method according to claim 1, characterized in that: The catalyst is 4-dimethylaminopyridine, and the molar ratio of nadic anhydride to the catalyst is (1.6-1.7):
1.
5. A monomer prepared by the method according to any one of claims 1 to 4.
6. A method for preparing a polymer for preparing a polynorbornene imide film, characterized in that: include: (i) under a dry nitrogen environment, dissolving the monomer described in claim 5 in an ultra-dry dichloromethane solution to obtain a solution D; (ii) under a dry nitrogen environment, dissolving the Grubbs 2nd generation catalyst in an ultra-dry dichloromethane solution to obtain a solution E; (iii) under a dry nitrogen environment, solution D and solution E were mixed, stirred at room temperature for 6 to 8 hours, and then the stop agent vinyl ethyl ether was added and the stirring was continued for 30 to 40 minutes; (iv) adding the solution after the reaction dropwise into a methanol solution to obtain a solid product, subjecting the solid product to Soxhlet extraction using methanol as the solution for 45-50 hours, and finally drying in vacuo at 60° C. for 22-26 hours to obtain a polymer.
7. The preparation method according to claim 6, characterized in that: The mass volume ratio of monomer, Grubbs 2nd generation catalyst and stopper vinyl ethyl ether is 2g:(18-22)mg:(2-3)mL.
8. A polymer prepared by the method according to claim 6 or 7.
9. A method for preparing a polynorbornene imide film, characterized in that: The polymer described in claim 8 is dissolved in an ultra-dry dichloromethane solution, and then formed into a film on a glass plate by a solution casting method to obtain a wet film, which is dried to obtain a dry film, and the dry film is vacuum dried to obtain a polynorbornene imide film.
10. An application of the polynorbornene imide film prepared by the method according to claim 9, characterized in that: Used as insulating medium in the preparation of electrical insulation devices.