A bio-based capacitor insulating oil and its preparation method

Abstract

The present invention belongs to the technical field of insulating oils, and relates to a bio-based capacitor insulating oil and a preparation method thereof. The raw materials for preparing the capacitor insulating oil provided by the present invention include: non-edible vegetable oil, antioxidant, pour point depressant, and modified fat-soluble dietary fiber. The present invention verifies that Jatropha curcas oil, mustard oil, and rice bran oil can be used as non-edible oils for capacitor insulating oils. Moreover, the capacitor insulating oil provided by the present invention is non-toxic by mouth, can be completely biodegradable, has a 21-day biodegradation rate of 98%, has higher flash point and ignition point, and has higher safety compared with the existing capacitor insulating oils, and belongs to an environment-friendly capacitor insulating oil.

Description

Technical Field

[0001] The present invention belongs to the technical field of insulating oil, and relates to a capacitor insulating oil and a preparation method thereof. Background Art

[0002] The dielectric of a capacitor consists of insulating oil and a film. The insulating oil not only cooperates with the film to play an insulating role, but also plays a role in cooling and heat dissipation during operation. Currently, the insulating oils used in capacitors mainly include benzyltoluene (M / DBT), diarylethane (PXE), phenylethylphenylethane (PEPE), etc. These insulating oils have the advantages of excellent insulating performance and low-temperature performance, but they are all chemical products, with disadvantages such as certain toxicity, poor environmental protection performance, and inability to be completely degraded.

[0003] The raw materials for preparing the insulating oil used in capacitors include capacitor insulating oils made from edible vegetable oils. For example, the raw materials for preparing the natural ester insulating liquid in CN113881481A include: soybean oil 96.0%-99.0%, antioxidant 0.4%-2.5%, pour point depressant 0.1%-0.5%, and auxiliary agent 0.1%-1.0%; the antioxidant consists of tocopherol, sterol, antioxidant T501, and citric acid. Therefore, in the production process of capacitor insulating oil, raw materials account for more than 60% of the total cost. How to obtain raw material oils with large-scale supply, low price, and suitable for energy use is the key problem that must be solved in the industrialization of capacitor insulating oil; affected by the trade environment, food prices are erratic, the market of edible vegetable oils fluctuates violently, and prices rise and fall alternately, which is not conducive to the large-scale production of capacitor insulating oil.

[0004] Currently, the insulating oils commonly used in market capacitors are all mineral insulating oil products, which have certain toxicity, poor environmental protection performance, and cannot be completely degraded; there are also capacitor insulating oils prepared from edible vegetable oils, but the raw materials used in the preparation generally contain toxic or difficult-to-degrade components, and edible vegetable oils also have large price fluctuations, making it difficult to achieve the large-scale production of capacitor insulating oil. Summary of the Invention

[0005] The purpose of the present invention is to provide a non-toxic and easily degradable capacitor insulating oil, which uses non-edible vegetable oil as the raw material, has simple preparation raw materials, and the price of non-edible vegetable oil is stable, suitable for large-scale production.

[0006] Based on the above purpose, the present invention provides a capacitor insulating oil and a preparation method thereof to meet this need in the field.

[0007] On the one hand, the present invention relates to a capacitor insulating oil, and the preparation raw materials thereof include: non-edible vegetable oil, antioxidant, and pour point depressant; by mass ratio, the addition amount of the antioxidant in the capacitor insulating oil is 0.1-2%; the addition amount of the pour point depressant in the capacitor insulating oil is 0.1-2%; the non-edible vegetable oil is selected from any one of jatropha oil, mustard oil, and rice bran oil; the antioxidant is selected from one or a combination of two of 3,5-di-tert-butyl-4-hydroxyphenyl propionate and octadecyl 3,5-di-tert-butyl-4-hydroxyphenyl propionate; the pour point depressant is polymethacrylate.

[0008] Further, in the capacitor insulating oil provided by the present invention, the preparation raw materials further include: modified fat-soluble dietary fiber; by mass ratio, the addition amount of the modified fat-soluble dietary fiber in the capacitor insulating oil is 0.1-2%; the modified fat-soluble dietary fiber is the fat-soluble dietary fiber after microwave oxidation.

[0009] Further, in the capacitor insulating oil provided by the present invention, the preparation method of the modified fat-soluble dietary fiber includes: mixing dietary fiber with 4-6 w% hydrogen peroxide and performing microwave treatment at 500-1000 W for 2-5 min.

[0010] On the other hand, the present invention relates to a preparation method of the above capacitor insulating oil, including: obtaining a base oil by subjecting the non-edible vegetable oil to decolorization, deacidification, and water washing treatments, and finally adding additives for preparing finished oil.

[0011] Further, in the preparation method of the capacitor insulating oil provided by the present invention, the preparation of the finished oil includes: weighing the base oil, the antioxidant, and the pour point depressant in proportion, heating to 75±5°C under vacuum conditions, stirring and reacting for 3 h, and then filtering using a filtering device with a 0.45 μm pore size filter membrane to obtain the capacitor insulating oil.

[0012] Further, in the preparation method of the capacitor insulating oil provided by the present invention, the decolorization includes: taking the non-edible vegetable oil, heating to 80±5°C, adding a solid adsorbent accounting for 1.5-5.0% of the weight of the non-edible vegetable oil, maintaining a vacuum state, stirring and adsorbing for decolorization for 1-1.5 h, and then filtering using a 1 μm pore size filter membrane to remove solid substances in the oil.

[0013] Further, in the preparation method of the capacitor insulating oil provided by the present invention, the deacidification includes: taking the decolorized non-edible vegetable oil, heating it to 55±5°C, and adding potassium hydroxide solution at the same temperature as the decolorized non-edible vegetable oil at a flow rate of 3 mL / min under stirring conditions, continuing to stir and react for 3 h, and then centrifuging for oil-water separation to remove the lower aqueous solution; the dosage of the potassium hydroxide solution is 25% by volume of the decolorized non-edible vegetable oil, and the concentration of the potassium hydroxide solution is 10 times the theoretical alkali amount for neutralizing the acidic substances in the decolorized non-edible vegetable oil.

[0014] Further, in the preparation method of the capacitor insulating oil provided by the present invention, the water washing includes: taking the decolorized and deacidified non-edible vegetable oil, heating it to 85±5°C, adding 25% by volume of deionized water at the same temperature, reacting for 2 h under stirring conditions, and then centrifuging for oil-water separation to remove the lower aqueous solution to obtain the base oil.

[0015] Further, in the preparation method of the capacitor insulating oil provided by the present invention, the preparation of the finished product oil includes: weighing the base oil, the antioxidant, the pour point depressant, and the modified fat-soluble dietary fiber in proportion; by mass ratio, the addition amount of the modified fat-soluble dietary fiber is 0.1-2%; the modified fat-soluble dietary fiber is the dietary fiber after microwave oxidation.

[0016] On the other hand, the present invention relates to a capacitor dielectric, which includes the above-mentioned capacitor insulating oil.

[0017] Compared with the prior art, the present invention has the following beneficial effects or advantages.

[0018] The capacitor insulating oil of the present invention is derived from plants, the additives are non-toxic, non-toxic by mouth (LD50 is greater than 5000 mg / kg), can be completely biodegradable, and the biodegradation rate in 21 days is 98%. It has higher flash point and ignition point, and has higher safety compared with the existing capacitor insulating oil, and belongs to an environmentally friendly capacitor insulating oil. The capacitor insulating oil of the present invention has better antioxidant performance compared with the current environmentally friendly insulating oil. The present invention uses non-edible oil and will not be affected by the shortage of edible oil in its popularization and use. Although the capacitor insulating oil provided by the present invention can meet the use requirements of capacitor insulating oil when prepared with non-edible vegetable oil and antioxidant, its antioxidant performance, acid value, kinematic viscosity and pour point are relatively poor. Therefore, the present invention further adds a pour point depressant and a modified fat-soluble dietary fiber to the preparation raw materials. The present invention finds through experiments that when preparing capacitor insulating oil, adding modified fat-soluble dietary fiber can effectively improve the antioxidant performance, kinematic viscosity and pour point performance, especially the acid value and kinematic viscosity after the oxidation stability test, but when the addition amount is too large, it will affect other performances. Specific embodiments

[0019] To more clearly illustrate the advantages of the present invention, the following specific examples are used for detailed description in this text. However, the present invention is by no means limited thereto. Unless otherwise specified, the experimental methods used in the examples are all conventional methods. The materials, reagents, etc. used in the examples can be obtained from commercial sources unless otherwise specified.

[0020] Example 1

[0021] This example provides the preparation process of capacitor insulating oil.

[0022] (1) Decolorization: Inject a certain amount of oil sample into the decolorization reaction tank, heat it up to 80 ± 5 °C, add a solid adsorbent (clay, silica gel or activated carbon) accounting for 1.5 - 5.0% of the oil weight. The reaction tank is maintained in a vacuum state, and the mixture is stirred and adsorbed for decolorization for 1 - 1.5 h. Then, the reactants are filtered while it is hot using a filtering device with a 1 μm pore size filter membrane to remove solid substances such as impurities and adsorbent in the oil, obtaining the decolorized oil sample. The acid value of the oil sample is measured according to GB 5009.229 - 2016.

[0023] (2) Deacidification: Inject the decolorized oil sample into the caustic refining tank, heat it up to 55 ± 5 °C, and under stirring conditions, add a potassium hydroxide solution with the same temperature as the oil sample at a flow rate of 3 mL / min. The volume of the potassium hydroxide solution is 25% of the oil sample volume (the concentration of the potassium hydroxide solution is 10 times the theoretical base amount for neutralizing acidic substances in the oil). After adding the potassium hydroxide solution, continue to stir and react for 3 h. Then, transfer the reaction mixture into a centrifuge tube for oil - water separation, and remove the lower aqueous solution to obtain the caustic - refined oil sample.

[0024] (3) Water washing: Transfer the caustic - refined oil sample into the reaction tank, heat it up to 85 ± 5 °C, add deionized water with the same temperature as the oil sample and a volume of 25% of the oil volume. React under stirring conditions for 2 h. Then, transfer the reaction mixture into a centrifuge tube for oil - water separation, and remove the lower aqueous solution to obtain the base oil.

[0025] (4) Preparation of finished oil: Weigh the additives (antioxidant, pour point depressant and / or modified fat - soluble dietary fiber) according to the proportion, add them together with the base oil into the reaction tank, heat it up to 75 ± 5 °C under vacuum conditions, stir and react for 3 h. Then, use a filtering device with a 0.45 μm pore size filter membrane to filter and obtain the capacitor insulating oil.

[0026] Through multiple experiments and verifications in this example, for the capacitor insulating oil prepared by the above - mentioned method, when the types of the oil sample and the additives are the same, the performance has no significant difference.

[0027] Example 2

[0028] This example provides a performance comparison test of the capacitor insulating oil prepared by the present invention.

[0029] Test method:

[0030] Breakdown voltage: GB / T 507; Dielectric loss factor, relative permittivity: GB / T 5654; Relative density: ASTM D1298; Acid value: IEC 62021-3; Kinematic viscosity: GB / T 265; Flash point (closed cup): GB / T 261; Fire point: GB / T 3536; Pour point: GB / T 3535; Gas evolution: GB / T 11142; Oral toxicity: GB / T 21757; 28-day biodegradation rate: OECD 301F; Chromaticity: GB / T 6540; Oxidation stability: Refer to NB / SH / T 0811. The lower the acid value, dielectric loss factor, and increment of kinematic viscosity after reaction, the better the antioxidant performance.

[0031] Test grouping:

[0032] No. 1: 98.5 w% mustard oil + 1 w% 3,5-di-tert-butyl-4-hydroxyphenyl propionate + 0.5 w% polymethacrylate; No. 2: PXE, an imported insulating oil from Japan that is widely used in the market. The preparation method refers to Example 1.

[0033] The test results are shown in Table 1.

[0034] Table 1: Results of performance comparison test

[0035]

[0036]

[0037] As can be seen from Table 1, for the capacitor insulating oil provided by the present invention, when prepared with non-edible vegetable oil and antioxidant, it has higher flash point and fire point, and has higher safety compared with the existing capacitor insulating oil, but has poor performance in terms of acid value, kinematic viscosity, and pour point.

[0038] Example 3

[0039] This example provides a performance comparison test of the capacitor insulating oil prepared by the present invention.

[0040] The test method is the same as that in Example 2.

[0041] The dietary fiber used in this example is purchased from Shenzhen Yinuo Food Co., Ltd.

[0042] Test grouping:

[0043] No. 3: 97.5 w% mustard seed oil + 0.5 w% polymethacrylate + 1 w% 3,5 - di - tert - butyl - 4 - hydroxyphenyl propionate + 1 w% modified fat - soluble dietary fiber; The preparation method of the modified fat - soluble dietary fiber is to mix oat dietary fiber with 4 w% hydrogen peroxide and irradiate with 500W microwave for 2 min.

[0044] No. 4: 99.4 w% Jatropha curcas oil + 0.1 w% octadecyl 3,5 - di - tert - butyl - 4 - hydroxyphenyl propionate + 0.5 w% polymethacrylate;

[0045] No. 5: 98 w% rice bran oil + 1 w% octadecyl 4 - hydroxyphenyl propionate + 1 w% 3,5 - di - tert - butyl - 4 - hydroxyphenyl propionate;

[0046] No. 6: 97.5 w% mustard seed oil + 1 w% 3,5 - di - tert - butyl - 4 - hydroxyphenyl propionate + 0.5 w% polymethacrylate + 1 w% oat fat - soluble dietary fiber;

[0047] No. 7: 98.4 w% Jatropha curcas oil + 1 w% 3,5 - di - tert - butyl - 4 - hydroxyphenyl propionate + 0.5 w% polymethacrylate + 0.1 w% modified fat - soluble dietary fiber; The preparation method of the modified fat - soluble dietary fiber is to mix wheat dietary fiber with 5 w% hydrogen peroxide and irradiate with 800W microwave for 3 min;

[0048] No. 8: 95.9 w% Jatropha curcas oil + 0.1 w% octadecyl 4 - hydroxyphenyl propionate + 2 w% polymethacrylate + 2 w% modified fat - soluble dietary fiber; The preparation method of the modified fat - soluble dietary fiber is to mix wheat dietary fiber with 6 w% hydrogen peroxide and irradiate with 1000W microwave for 5 min;

[0049] No. 9: 96.4 w% mustard seed oil + 0.5 w% 3,5 - di - tert - butyl - 4 - hydroxyphenyl propionate + 0.1% polymethacrylate + 3 w% modified fat - soluble dietary fiber; The preparation method of the modified fat - soluble dietary fiber is to mix oat dietary fiber with 5 w% hydrogen peroxide and irradiate with 800W microwave for 3 min.

[0050] The test results are shown in Table 2.

[0051] Table 2: Test Results of Performance Tests

[0052]

[0053]

[0054] As can be seen from Table 2, in the preparation process of non-edible vegetable oil and antioxidant in this embodiment, a certain amount of modified fat-soluble dietary fiber is added, which can effectively improve various properties of the capacitor insulating oil, especially can reduce the acid value and enhance the antioxidant performance. Further comparative studies in this embodiment show that when using fat-soluble dietary fiber, its influence on the performance of capacitor insulating oil is not prominent, and in actual experiments, the fat-soluble dietary fiber itself also contains a certain color, which will affect the chromaticity of the final capacitor insulating oil; while when using modified fat-soluble dietary fiber, if the dosage of modified fat-soluble dietary fiber is excessive, it will instead damage the performance of capacitor insulating oil.

[0055] As described above, the present invention can be preferably implemented. The above embodiments are only descriptions of the preferred implementation modes of the present invention, and do not limit the scope of the present invention. Without departing from the design spirit of the present invention, various changes and improvements made by those of ordinary skill in the art to the technical solutions of the present invention shall fall within the protection scope determined by the present invention.

Claims

1. A bio-based capacitor insulating oil, characterized in that, The preparation raw materials include: non-edible vegetable oil, antioxidant, pour point depressant; By mass ratio, the addition amount of the antioxidant in the capacitor insulating oil is 0.1-2%; By mass ratio, the addition amount of the pour point depressant in the capacitor insulating oil is 0.1-2%; The non-edible vegetable oil is selected from any one of Jatropha curcas oil, mustard oil, and rice bran oil; The antioxidant is selected from one or a combination of two of 3,5-di-tert-butyl-4-hydroxyphenyl propionate and octadecyl 3,5-di-tert-butyl-4-hydroxyphenyl propionate; The pour point depressant is polymethacrylate; The preparation raw materials further include: modified fat-soluble dietary fiber; by mass ratio, the addition amount of the modified fat-soluble dietary fiber in the capacitor insulating oil is 0.1-2%; The modified fat-soluble dietary fiber is the fat-soluble dietary fiber after microwave oxidation; the preparation method of the modified fat-soluble dietary fiber includes: mixing the dietary fiber with 4-6 w% hydrogen peroxide and irradiating with 500-1000 W microwave for 2-5 min.

2. The preparation method of the bio-based capacitor insulating oil according to claim 1, characterized in that, Including: Subjecting the non-edible vegetable oil to decolorization, deacidification, and water washing to obtain a base oil, and finally adding an antioxidant, a pour point depressant, and the modified fat-soluble dietary fiber for the preparation of the finished oil; The preparation of the finished oil includes: weighing the base oil, the antioxidant, the pour point depressant, and the modified fat-soluble dietary fiber in proportion; By mass ratio, the addition amount of the modified fat-soluble dietary fiber is 0.1-2%; The modified fat-soluble dietary fiber is the dietary fiber after microwave oxidation.

3. The preparation method of the bio-based capacitor insulating oil according to claim 2, wherein, The preparation of the finished oil includes: weighing the base oil, the antioxidant, and the pour point depressant in proportion, heating to 75±5 °C under vacuum conditions, stirring and reacting for 3 h, and then filtering with a filtering device with a 0.45 μm pore size filter membrane to obtain the capacitor insulating oil.

4. The preparation method of the bio-based capacitor insulating oil according to claim 2, characterized in that The decolorization includes: taking the non-edible vegetable oil, heating to 80±5 °C, adding a solid adsorbent accounting for 1.5-5.0% of the weight of the non-edible vegetable oil, maintaining a vacuum state, stirring and adsorbing for decolorization for 1-1.5 h, and then filtering with a 1 μm pore size filter membrane to remove the solid substances in the oil.

5. The preparation method of the bio-based capacitor insulating oil according to claim 2, characterized in that, The deacidification includes: taking the decolorized non-edible vegetable oil, heating to 55±5 °C, adding a potassium hydroxide solution at the same temperature as the decolorized non-edible vegetable oil at a flow rate of 3 mL / min under stirring conditions, continuing to stir and react for 3 h, and then centrifuging for oil-water separation to remove the lower aqueous solution; The dosage of the potassium hydroxide solution is 25% by volume of the decolorized non-edible vegetable oil, and the concentration of the potassium hydroxide solution is 10 times the theoretical base amount for neutralizing the acidic substances in the decolorized non-edible vegetable oil.

6. The preparation method of the bio-based capacitor insulating oil according to claim 2, wherein, The water washing includes: taking the non-edible vegetable oil after decolorization and deacidification, heating to 85±5 °C, adding deionized water at the same temperature accounting for 25% by volume, reacting for 2 h under stirring conditions, and then centrifuging for oil-water separation to remove the lower aqueous solution to obtain the base oil.

7. A capacitor dielectric, characterized in that, Including the bio-based capacitor insulating oil described in claim 1.

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