Preparation method and application of fluorine-containing aromatic polythiourea with high breakdown resistance

Abstract

The invention relates to the technical field of energy storage, and provides a preparation method of high-breakdown-resistance fluorine-containing aromatic polythiourea aiming at the problems of low dielectric constant, low breakdown-resistance strength, large energy loss and the like of a full-flexible polymer film, the preparation method comprises the following steps: firstly, carrying out microwave polymerization on 2, 2-bis (3-amino-4-hydroxyphenyl)-hexafluoropropane (BAHHHFP) and thiourea; a high-molecular F-ArPTU dielectric polymer is prepared; performing vacuum drying to obtain a product F-ArPTU powder; the product is prepared into a dielectric polymer film for testing and verifying the breakdown resistance and the energy storage performance of the dielectric polymer film. The method is simple and efficient in path, and the prepared polymer can be applied to flexible film capacitors.

Description

Technical Field

[0001] The invention relates to the technical field of organic dielectric energy storage, in particular to a preparation method of fluorine-containing aromatic polythiourea with high breakdown resistance and application thereof in capacitors. Background Art

[0002] With the rapid development of electronic power systems, dielectric materials with high energy storage density, low loss, high breakdown strength and good temperature stability have become the best candidate materials for capacitors. The traditional dielectric energy storage material biaxially oriented polypropylene (BOPP) has a low dielectric constant of only 2.2 to 2.3, so the energy storage density is low and cannot meet the needs of the rapidly developing electronics and power industries. For the recently developed high dielectric energy storage material polyvinylidene fluoride-based polymers (PVDF-based polymers), the energy storage density of the fluorine-containing material can be as high as 50-60 through defect regulation, which is much greater than the traditional BOPP material. However, the dipole coupling together causes the system to produce large dielectric and ferroelectric losses, which often generates a lot of heat during use, reducing the service life of the film itself. Summary of the invention

[0003] In order to overcome the problem of low energy storage density of commercial polypropylene-based capacitors, the present invention proposes a fluorine-containing aromatic polythiourea polymer, the thiourea groups on the main chain of which are effectively separated by phenyl groups, reducing the mutual coupling between dipoles and dipoles, so that the system can maintain a large polarization strength while greatly reducing the dielectric and ferroelectric losses of the system itself, and having a high breakdown strength, realizing the development needs of capacitors with high energy storage density and low dielectric loss, and promoting the iterative update of new organic capacitor films. The preparation method provided by the present invention is simple and efficient, and is expected to be widely promoted and applied.

[0004] In order to achieve the above object, the present invention adopts the following technical solutions:

[0005] A method for preparing a highly breakdown-resistant fluorinated aromatic polythiourea comprises the following steps:

[0006] Step 1, adding 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (BAHHHFP), thiourea and catalyst p-toluenesulfonic acid into N-methylpyrrolidone to dissolve and mix, and intermittently applying microwaves to the mixed solution for microwave polymerization;

[0007] Step 2: Wash the solution after the reaction in step 1 with methanol and then dry it in vacuum to obtain the product F-ArPTU powder, which is a dielectric polymer with high breakdown strength and low dielectric loss;

[0008] Step 3: Dissolve the F-ArPTU powder obtained in step 2 in N,N-dimethylformamide (DMF), cast it on a smooth substrate, dry it, and then remove the film from the substrate to obtain a F-ArPTU polymer film.

[0009] Preferably, in step 1, the molar ratio of 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane, thiourea and p-toluenesulfonic acid is 1:1:0.1.

[0010] Preferably, the microwave polymerization in step 1 specifically comprises: subjecting the mixed solution to microwave polymerization for 3 minutes three times under microwave conditions of 18 Hz, stopping the microwave application for 1 minute after each microwave polymerization for 3 minutes; then subjecting the mixed solution to microwave polymerization for 3 minutes twice under microwave conditions of 21 Hz, stopping the microwave application for 1 minute after each microwave polymerization for 3 minutes; and finally subjecting the mixed solution to microwave polymerization for 3 minutes once under microwave conditions of 25 Hz.

[0011] Preferably, in step 2, suction filtration is used to perform the methanol washing, and the number of methanol washings is 3-5 times.

[0012] Preferably, the vacuum drying in step 2 specifically comprises: pouring the solution obtained in step 1 into an open glass dish, and periodically evacuating the glass dish to ensure the vacuum degree.

[0013] Preferably, the reaction conditions of the vacuum drying are: drying at 60° C. for 36 hours and then vacuum drying at 120° C. for 12 hours.

[0014] Preferably, in step three, before pouring, the substrate is first leveled with a spirit level.

[0015] Preferably, the drying in step three specifically includes: first drying at 60° C. for 2 hours, and then drying at 120° C. for 8 hours.

[0016] Preferably, the thickness of the F-ArPTU polymer film in step 3 is 30-40 μm.

[0017] The present invention also provides an application of the F-ArPTU polymer film prepared by the preparation method in the preparation of a flexible film capacitor.

[0018] The beneficial effects of the present invention are as follows: the method of the present invention is simple and efficient, the prepared F-ArPTU dielectric polymer has a relatively high dielectric constant, while the breakdown resistance is significantly improved and the loss is reduced, and the excellent ductility of the polymer material is maintained to meet the needs of industrial production. Therefore, the F-ArPTU dielectric polymer is a new dielectric polymer that can simultaneously achieve a high dielectric constant and a high breakdown strength, and is suitable for use in capacitors. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1Schematic diagram of the preparation process of F-ArPTU.

[0020] Figure 2 This is a physical picture of the F-ArPTU powder prepared in Example 1.

[0021] Figure 3 It is the infrared spectrum of F-ArPTU prepared in Example 1.

[0022] Figure 4 It is the hydrogen nuclear magnetic resonance spectrum of F-ArPTU prepared in Example 1.

[0023] Figure 5 This is a diagram showing the breakdown resistance of F-ArPTU prepared in Example 1.

[0024] Figure 6 Schematic diagram of the relationship between the dielectric constant, dielectric loss and frequency of F-ArPTU prepared in Example 1. DETAILED DESCRIPTION

[0025] The technical solution of the present invention is further described below through specific embodiments.

[0026] In the present invention, unless otherwise specified, the raw materials and equipment used can be purchased from the market or are commonly used in the art. The methods in the embodiments, unless otherwise specified, are all conventional methods in the art.

[0027] Example 1

[0028] Preparation method of F-ArPTU dielectric polymer, such as Figure 1 As shown, the steps are as follows:

[0029] Step 1: 1.975 g of 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane, 0.6 g of thiourea, and 0.0172 g of p-toluenesulfonic acid are used as catalysts, and the molar ratio of the three substances is 1:1:0.1. 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane (BAHHHFP), thiourea, and p-toluenesulfonic acid are added to N-methylpyrrolidone to dissolve and mix, and the mixed solution is subjected to microwave polymerization for 3 minutes three times under microwave conditions of 18 Hz, and then microwave polymerization is carried out twice under microwave conditions of 21 Hz for 3 minutes, and finally microwave polymerization is carried out once under microwave conditions of 25 Hz for 3 minutes. After each microwave polymerization for 3 minutes, the microwave application is stopped for 1 minute. During the reaction, if the amount of solvent is less than 20 ml, it is appropriately supplemented to 100 ml.

[0030] Step 2: Wash the solution after the reaction in step 1 with methanol for 3-5 times, dry it at 60°C for 36 hours, and then vacuum dry it at 100°C for 12 hours to obtain the product F-ArPTU powder, which is a dielectric polymer with high breakdown strength and low dielectric loss. The preparation process is as follows: Figure 1 Its macroscopic morphology is as shown in Figure 2 As shown, the powder is light yellow; in step 2, during vacuum drying, pour the solution into a larger glass dish and evacuate the dish at regular intervals to ensure the vacuum degree.

[0031] Step three, dissolve the F-ArPTU powder obtained in step two in N, N-dimethylformamide (DMF), use a magnetic stirrer to stir until the mixture is evenly mixed; then, cast it on a smooth glass substrate that has been leveled in advance by a solution casting method and dry it. The drying process is: first bake at 60°C for 2 hours and then bake at 120°C for 8 hours. After complete drying, the F-ArPTU dielectric polymer is obtained. The thickness of the F-ArPTU polymer film is 30 to 40 μm. The polymer has good ductility and high temperature resistance, low dielectric loss, and low heat generation, and has the possibility of being applied to high-temperature dielectric materials. Compared with other organic / inorganic composite dielectric materials, the polymer can provide the characteristics of high breakdown strength, has good compatibility with other dielectric polymers, can meet the requirements of the biaxial stretching process of industrial production, and can be used to make capacitors.

[0032] Performance Testing

[0033] The invention synthesizes a highly breakdown-resistant dielectric polymer F-ArPTU by replacing conventional heating reaction with microwave polymerization.

[0034] Figure 3 The infrared spectrum of F-ArPTU is shown. From the FTIR spectrum, it was observed that the sample has a peak at 3413 cm -1 (NH stretching vibration), 3400-3000cm -1 (OH stretching vibration), 1662cm -1 (C=S stretching vibration), 1593cm -1 (CC skeleton vibration of benzene ring), 1495cm -1 (NH bending vibration), 1241cm -1 (CF stretching vibration) and 1130cm -1 (CN stretching vibration) shows a typical characteristic band. Figure 4 The nuclear magnetic resonance spectrum also showed resonance signal peaks at 9.9ppm (—OH), 10.5ppm (aromatic amine), 10.3ppm (thiourea amino), and 7.5ppm, 7.1ppm, 6.9ppm (benzene ring), which proved that F-ArPTU was successfully synthesized.

[0035] Figure 5 The breakdown strength of F-ArPTU was tested. According to ASTM D149-2004, the breakdown strength of dielectric materials was measured using an AHDZ-10 / 100 AC dielectric strength tester (Shanghai Lanbo Electronics Co., Ltd., China). The sample was placed between two copper ball electrodes with a diameter of 10 mm, and the electrode system containing the test sample was immersed in pure silicone oil. A test voltage was applied to the two spherical electrodes and increased at a rate of 2KV / s until the sample was punctured. The measurement was performed at a different point, and the breakdown test was repeated 10 times for each sample. The sample breakdown strength can reach up to 790kV / mm, which is much higher than BOPP.

[0036] Figure 6 The dielectric constant and dielectric loss of F-ArPTU were tested. The sample was fixed in two metal masks with an aperture of 3mm and placed in a coating instrument (SBC small ion sputtering coating instrument of Beijing Zhongke Instrument Technology Co., Ltd.), and the instrument was required to maintain a certain degree of vacuum before sputtering. The temperature of the coating was controlled, the sputtering time was 110s each time, the sputtering current was 2-3mA, and the plating was repeated 10-12 times to obtain two opposite gold electrodes on both sides of the film. Then an impedance analyzer was used to test the dielectric constant of the material. The scanning frequency was 100-106Hz, and the loading voltage was 1V. When the measurement frequency was 1000Hz, the dielectric constant of F-ArPTU was measured to be about 6.6 under low-frequency conditions, and the loss was only 0.04, which was significantly better than BOPP.

[0037] The above description is only a preferred embodiment of the present invention and does not limit the present invention in any form. Although the present invention has been disclosed as a preferred embodiment as above, it is not used to limit the present invention. Any technician familiar with this profession can make some changes or modifications to equivalent embodiments of equivalent changes using the technical contents disclosed above without departing from the scope of the technical solution of the present invention. However, any simple modification, equivalent change and modification made to the above embodiments based on the technical essence of the present invention without departing from the content of the technical solution of the present invention still fall within the scope of the technical solution of the present invention.

Claims

1. A method for preparing a highly breakdown-resistant fluorinated aromatic polythiourea, characterized in that: The following steps are involved: Step 1, adding 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane, thiourea and catalyst p-toluenesulfonic acid into N-methylpyrrolidone to dissolve and mix, and intermittently applying microwaves to the mixed solution for microwave polymerization; Step 2: Wash the solution after the reaction in step 1 with methanol and then dry it in vacuum to obtain the product F-ArPTU powder, which is a dielectric polymer with high breakdown strength and low dielectric loss; Step 3: Dissolve the F-ArPTU powder obtained in step 2 in N,N-dimethylformamide (DMF), cast it on a smooth substrate, dry it, and then remove the film from the substrate to obtain a F-ArPTU polymer film.

2. The method for preparing a highly breakdown-resistant fluorinated aromatic polythiourea according to claim 1, characterized in that: In step 1, the molar ratio of 2,2-bis(3-amino-4-hydroxyphenyl)-hexafluoropropane, thiourea and p-toluenesulfonic acid is 1:1:0.

1.

3. The method for preparing a highly breakdown-resistant fluorinated aromatic polythiourea according to claim 1, characterized in that: The microwave polymerization in step 1 specifically includes: subjecting the mixed solution to microwave polymerization for 3 minutes three times under microwave conditions of 18 Hz, stopping the microwave application for 1 minute after each microwave polymerization for 3 minutes; then subjecting the mixed solution to microwave polymerization for 3 minutes twice under microwave conditions of 21 Hz, stopping the microwave application for 1 minute after each microwave polymerization for 3 minutes; and finally subjecting the mixed solution to microwave polymerization for 3 minutes once under microwave conditions of 25 Hz.

4. The method for preparing a highly breakdown-resistant fluorinated aromatic polythiourea according to claim 1, characterized in that: In step 2, the methanol washing is performed by suction filtration, and the number of methanol washings is 3-5 times.

5. The method for preparing a highly breakdown-resistant fluorinated aromatic polythiourea according to claim 1, characterized in that: The vacuum drying in step 2 specifically comprises: pouring the solution obtained in step 1 into an open glass dish, and periodically evacuating the glass dish to ensure the vacuum degree.

6. The method for preparing a highly breakdown-resistant fluorinated aromatic polythiourea according to claim 5, characterized in that: The reaction conditions of the vacuum drying are: drying at 60° C. for 36 h and then vacuum drying at 120° C. for 12 h.

7. The method for preparing a highly breakdown-resistant fluorinated aromatic polythiourea according to claim 1, characterized in that: Step 3: Before pouring, first use a level to level the base plate.

8. The method for preparing a highly breakdown-resistant fluorinated aromatic polythiourea according to claim 1, characterized in that: The drying in step 3 specifically includes: first drying at 60° C. for 2 hours, and then drying at 120° C. for 8 hours.

9. The method for preparing a highly breakdown-resistant fluorinated aromatic polythiourea according to claim 1, characterized in that: Step 3: The thickness of the F-ArPTU polymer film is 30-40 μm.

10. Use of the F-ArPTU polymer film obtained according to the method for preparing a high breakdown resistance fluorinated aromatic polythiourea according to any one of claims 1 to 9 in the preparation of flexible film capacitors.

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