Polymer for winding insulation and preparation method and application thereof

Abstract

The invention discloses a polymer for winding insulation and a preparation method and application thereof, and belongs to the technical field of electrical insulation materials and preparation thereof. According to the invention, the problem of low yield in the existing preparation of polynorbornene dianhydride is solved. According to the preparation method, the NBEA is polymerized by using DMF as a solvent, the high-performance polynorbornene dianhydride polymer is efficiently prepared by using the excellent dissolving capacity and low interference to the polymerization reaction of DMF, and the yield reaches 30%. Moreover, the prepared polynorbornene dianhydride contains two anhydride groups, the number of traps in the material is increased, the traps can capture and limit charge carriers and reduce charge flow, so that the insulating property of the material is improved, and after the two anhydride groups are introduced, the originally fragile polynorbornene becomes tough, so that the service life of the material is prolonged, and the service life of the material is prolonged. And the insulating material with high insulating property and excellent mechanical property is obtained.

Description

Technical Field

[0001] The present invention relates to a polymer for winding insulation, a preparation method thereof and an application thereof, belonging to the technical field of electrical insulation materials and their preparation. Background Art

[0002] During the operation of motors and electrical equipment, the insulating material between windings is in a high-voltage operating environment for a long time. Uneven electric field distribution may occur inside the insulating layer, leading to partial discharge and overvoltage shock. These two will gradually damage the insulating material, causing it to lose its insulating performance and resulting in the damage of electrical equipment. Moreover, with the development of the new energy industry and the new power system, new requirements are put forward for traditional insulating materials. Therefore, there is an urgent need to develop insulating materials with high insulating performance and excellent mechanical properties.

[0003] As a material that exhibits excellent insulation under high electric fields, poly(norbornene anhydride) has significant advantages among dielectric polymers. In addition, poly(norbornene anhydride) has a low dielectric loss, which helps to improve the insulating performance of the material. And because poly(norbornene anhydride) is easy to modify the side chain to meet the corresponding working conditions, these characteristics make poly(norbornene anhydride) have important application value in insulating materials. However, the yield of poly(norbornene anhydride) prepared by existing methods is very low. Therefore, it is very necessary to provide an efficient polymerization method for norbornene anhydride. Summary of the Invention

[0004] Aiming at the problems existing in the preparation of existing poly(norbornene anhydride), the present invention provides a polymer for winding insulation, a preparation method thereof and an application thereof.

[0005] Technical Solution of the Invention

[0006] One of the purposes of the present invention is to provide a preparation method of a polymer for winding insulation, and the method includes the following steps:

[0007] (1) Under an anhydrous and oxygen-free nitrogen environment, dissolve norbornene anhydride in N,N-dimethylformamide to form solution A;

[0008] (2) Under an anhydrous and oxygen-free nitrogen environment, dissolve Grubbs II catalyst in N,N-dimethylformamide to form solution B;

[0009] (3) Under an anhydrous and oxygen-free nitrogen environment, mix solution A and solution B and stir evenly to obtain a mixed solution. The mixed solution reacts at 50 °C for 6-8 h, and then a terminator is added and stirred for another 30 min to stop the reaction;

[0010] (4) The reaction solution obtained in (3) was added dropwise to a cold methanol solution to obtain a solid product. Using methanol as the solution, the solid product was subjected to Soxhlet extraction and finally vacuum dried at 60 °C to obtain a polymer for winding insulation.

[0011] Further defined, the mass-volume ratio of norbornene dianhydride to N,N-dimethylformamide in (1) is 1.5 g: 20 ml.

[0012] Further defined, the mass-volume ratio of Grubbs II catalyst to N,N-dimethylformamide in (2) is 20 mg: 4 ml.

[0013] Further defined, the mass ratio of norbornene dianhydride to Grubbs II catalyst in the mixed solution of (3) is 1.5 g: 20 mg.

[0014] Further defined, the terminator in (3) is vinyl ethyl ether.

[0015] Further defined, the temperature of the cold methanol in (4) is 2 - 6 °C.

[0016] Further defined, the Soxhlet extraction time in (4) is 45 - 50 h.

[0017] The second object of the present invention is to provide a polymer for winding insulation prepared by the above method.

[0018] The third object of the present invention is to provide a method for preparing a polymer film for winding insulation. The method is to dissolve the above polymer for winding insulation in N,N-dimethylformamide, 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 polymer film for winding insulation.

[0019] Further defined, the temperature of the glass plate is 80 °C.

[0020] Further defined, the drying treatment temperature is 80 °C and the time is 3 h.

[0021] Further defined, the vacuum drying treatment temperature is 55 - 65 °C and the time is 24 h.

[0022] Further defined, the thickness of the obtained polymer film for winding insulation is 5 - 10 μm.

[0023] The fourth object of the present invention is to provide a polymer film for winding insulation prepared by the above method, specifically used as a winding insulation material for the preparation of electrical insulation devices.

[0024] Further defined, the electrical insulation devices include smart grids, new energy vehicles, and AC / DC transmission networks.

[0025] Beneficial effects:

[0026] In the present invention, N,N-dimethylformamide (DMF) is used as a single solvent to polymerize norbornene dianhydride (NBEA). By utilizing the excellent solubility of DMF and its low interference with the polymerization reaction, the efficient preparation of high-performance poly(norbornene dianhydride) polymers is achieved, with a yield reaching 30%. Moreover, the preparation method provided by the present invention optimizes the dosage of DMF and the reaction conditions, effectively increasing the yield of the polymerization reaction while reducing the generation of side reactions and impurities, simplifying the subsequent treatment process and the solvent recovery process, and reducing the environmental impact. Meanwhile, the poly(norbornene dianhydride) prepared contains two anhydride groups, increasing the number of traps in the material. These traps can capture and limit charge carriers, reducing the flow of charges, thereby improving the insulation performance of the material. After introducing two anhydride groups, the originally brittle poly(norbornene) becomes tough, obtaining an insulating material with high insulation performance and excellent mechanical properties. Description of the drawings

[0027] Figure 1 X-ray diffraction comparison diagrams of poly(norbornene dianhydride) films and poly(norbornene) films prepared in Example 1 and Comparative Example 3;

[0028] Figure 2 Fourier transform infrared spectroscopy comparison diagrams of poly(norbornene dianhydride) films and poly(norbornene) films prepared in Example 1 and Comparative Example 3;

[0029] Figure 3 Weibull distribution diagrams of breakdown field strengths of poly(norbornene dianhydride) films and poly(norbornene) films prepared in Example 1 and Comparative Example 3;

[0030] Figure 4 Dielectric spectroscopy diagram of the poly(norbornene dianhydride) film prepared in Example 1;

[0031] Figure 5 Real part conductivity spectroscopy diagram of the poly(norbornene dianhydride) film prepared in Example 1. Detailed implementation manners

[0032] To make the above objects, features, and advantages of the present invention more obvious and understandable, the following detailed description of the specific implementation manners of the present invention is provided in conjunction with the embodiments of the specification.

[0033] In the following description, many specific details are set forth to facilitate a thorough understanding of 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.

[0034] Second, the "one embodiment" or "embodiment" referred to herein means a specific feature, structure, or characteristic that may 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 an individual or selectively mutually exclusive embodiment with other embodiments.

[0035] Unless otherwise specified, the experimental methods used in the following examples are all conventional methods. The materials, reagents, methods, and instruments used, unless otherwise specified, are all conventional materials, reagents, methods, and instruments in this field. Those skilled in the art can obtain them through commercial channels, and the purity of the solid and liquid reagents used is analytical pure.

[0036] Example 1

[0037] Step 1: Dissolve 1.5 g of norbornene dianhydride (NBEA) monomer in 20 ml of N,N-dimethylformamide (DMF) under anaerobic conditions to form solution A.

[0038] Step 2: Place solution A in an oil bath and set the temperature to 50 °C.

[0039] Step 3: Weigh 20 mg of Grubbs II catalyst in a glove box and dissolve it in 4 ml of DMF to form solution B.

[0040] Step 4: Inject solution B into solution A and stir for 6 h at 50 °C to complete the polymerization reaction.

[0041] Step 5: After the reaction is completed, use 2 ml of vinyl ethyl ether to terminate the reaction and continue stirring for 30 min.

[0042] Step 6: Drop the reaction solution into methanol to precipitate a solid product. Soxhlet extract the obtained solid product for 48 h and finally dry it at 60 °C for 24 h to obtain a dry poly(norbornene dianhydride) polymer with a yield of 30%.

[0043] Step 7: Dissolve the dry norbornene dianhydride polymer in a DMF solution to prepare a 5 wt% precursor solution and stir for 2 h.

[0044] Step 8: Use the solution casting method to uniformly coat the precursor solution on a glass plate to obtain a wet film. Dry the wet film at 60 °C for 2 h to obtain a dry film, and then dry the dry film in a vacuum at 55 - 65 °C for 24 h to obtain a poly(norbornene dianhydride) film with a thickness of 7 μm.

[0045] Comparative Example 1

[0046] The difference between this comparative example and Example 1 is that the experimental temperatures in Steps 2 and 4 are different, while the other conditions are the same. Experiments were carried out at experimental temperatures of 20°C, 30°C, 40°C, 45°C, 55°C, and 60°C. The experimental results show that the highest yield can be obtained at 50°C, reaching 30%.

[0047] Comparative Example 2

[0048] The difference between this comparative example and Example 1 is that anhydrous dichloromethane is used as the solvent to replace DMF in Steps 1 and 3. The experimental results show that the polymerization of NBEA cannot be achieved using this scheme.

[0049] Comparative Example 3

[0050] Step 1: Under the protection of an inert gas, accurately weigh 1.5 g of norbornene monomer and dissolve it in 20 ml of anhydrous dichloromethane to form a homogeneous solution A.

[0051] Step 2: Inside an inert atmosphere glove box, accurately weigh 20 mg of Grubbs II catalyst and dissolve it in 4 ml of anhydrous dichloromethane to form solution B.

[0052] Step 3: Slowly inject solution B into solution A and carry out a polymerization reaction at room temperature for 6 h.

[0053] Step 4: After the polymerization is completed, immediately add 2 ml of vinyl ethyl ether to terminate the reaction, and continue stirring at room temperature for 30 min to ensure complete reaction.

[0054] Step 5: Slowly pour the reaction mixture into a large amount of pre-cooled methanol at 2 - 6°C to precipitate the polymer. Subsequently, wash it with methanol several times at room temperature to remove unreacted monomers and catalyst residues. Finally, dry it under vacuum at 60°C for 24 h to obtain a dry poly(norbornene) polymer.

[0055] Step 6: Dissolve the dry polymer in toluene at 110°C to form a 5 wt% precursor solution, and continuously stir at this temperature for 12 h.

[0056] Step 7: Uniformly coat the filtered precursor solution on a glass plate pre-heated to 80°C to form a wet film, and then dry it at this temperature for 3 h to form a dry film. Finally, further dry the dry film in a vacuum environment at 55°C for 24 h to obtain a poly(norbornene) film with a uniformly controlled thickness within the range of 5 μm.

[0057] Effect Example 1

[0058] (1) Figure 1X-ray diffraction comparison diagrams of the polybicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride film and the polynorbornene film prepared in Example 1 and Comparative Example 3. As can be seen from the figure, in the low-angle region (between about 10° and 40°) of polynorbornene, a distinct diffraction peak is shown, indicating that polynorbornene has a strong crystal structure reflection at this angle. Polybicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride also shows a distinct diffraction peak in the low-angle region (between about 10° and 40°), but the intensity is lower than that of polynorbornene, meaning that the introduction of two anhydride groups makes the crystal structure disordered, and the diffuse peak is not obvious.

[0059] (2) Figure 2 Fourier transform infrared spectroscopy comparison diagrams of the polybicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride film and the polynorbornene film prepared in Example 1 and Comparative Example 3. As can be seen from the figure, near 1700 cm -1 , there is a strong absorption peak, which is caused by the stretching vibration of the C=O carbonyl in the dianhydride. In the region of 1000 - 1300 cm -1 , there is an absorption peak of the C-O stretching vibration, which is the characteristic absorption of the ether bond (-C-O-C-) in the dianhydride. In the region above 3000 cm -1 , the absorption peak of the C-H stretching vibration weakens or disappears because the introduction of the dianhydride may change the vibration mode of the original C-H bond, all of which illustrate the successful introduction of two anhydride groups.

[0060] (3) Figure 3 Weibull distribution diagrams of the breakdown field strength of the polybicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride film and the polynorbornene film prepared in Example 1 and Comparative Example 3. As can be seen from the figure, the introduction of two anhydride groups increases the electronegativity, which helps to improve the breakdown field strength of the capacitor film, and raises the breakdown of polynorbornene to 400 MV / m.

[0061] (4) Figure 4 Dielectric constant spectrogram of the polybicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride film prepared in Example 1. As can be seen from the curve in the figure, the curve shows a typical dielectric relaxation behavior, that is, in a certain frequency range (near about 10 2 Hz), the dielectric constant reaches the minimum value while the dielectric loss reaches the maximum value.

[0062] (5) Figure 5 Real part conductivity spectrogram of the polybicyclo[2.2.1]hept-5-ene-2,3-dicarboxylic anhydride film prepared in Example 1. As shown in the figure, the real part conductivity shows an upward trend in the whole frequency range. In the low-frequency band (from about 10 0 Hz to 10 3 Hz), the conductivity is relatively low, about 10 -14 S / cm, and in the high-frequency band (from about 10 3 Hz to 10 6Hz), the conductivity increases significantly, reaching about 10 -7 S / cm.

[0063] Although the present invention has been disclosed above in a preferred embodiment, it is not intended to limit the present invention. Any person skilled in this technology can make various changes and modifications 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 polymer for winding insulation, characterized in that: include: (1) dissolving nadic anhydride in N,N-dimethylformamide in an anhydrous and oxygen-free nitrogen environment to form a solution A; (2) In an anhydrous and oxygen-free nitrogen environment, dissolving the Grubbs II catalyst in N,N-dimethylformamide to form solution B; (3) In an anhydrous and oxygen-free nitrogen environment, solution A and solution B are mixed and stirred to obtain a mixed solution, the mixed solution is reacted at 50° C. for 6-8 hours, and then a stop agent is added and stirred for 30 minutes to stop the reaction; (4) The reaction solution obtained in (3) is added dropwise to a cold methanol solution to obtain a solid product. The solid product is subjected to Soxhlet extraction using methanol as a solvent, and finally vacuum dried at 60° C. to obtain a polymer for winding insulation.

2. The preparation method according to claim 1, characterized in that: (1) The mass volume ratio of nadic anhydride and N,N-dimethylformamide is 1.5 g:20 ml.

3. The preparation method according to claim 1, characterized in that: (2) The mass volume ratio of Grubbs II catalyst and N,N-dimethylformamide is 20 mg:4 ml.

4. The preparation method according to claim 1, characterized in that: The mass ratio of nadic anhydride to Grubbs II catalyst in the mixed solution (3) is 1.5 g:20 mg.

5. The preparation method according to claim 1, characterized in that: (3) The stopper is vinyl ethyl ether.

6. The preparation method according to claim 1, characterized in that: (4) The temperature of the intermediate cooled methanol is 2-6°C.

7. The preparation method according to claim 1, characterized in that: (4) The extraction time is 45-50 hours.

8. A polymer for winding insulation prepared by the method according to any one of claims 1 to 7.

9. A method for preparing a polymer film for winding insulation, characterized in that: The polymer for winding insulation described in claim 8 is dissolved in N,N-dimethylformamide, 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 polymer film for winding insulation.

10. A polymer film for winding insulation prepared by the method according to claim 9, characterized in that: Used as winding insulation material in the preparation of electrical insulation devices.

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