Insulating oil containing vegetable oil and its preparation method and application

Abstract

The application discloses plant oil-containing insulating oil and a preparation method and application thereof, and belongs to the technical field of lubricating oil, and is used for solving the problems that plant oil-type insulating oil is prone to solidification at low temperature, and antioxidation stability and flame retardation need to be further improved in the prior art, wherein the preparation method of the plant oil-containing insulating oil comprises the following steps: uniformly mixing dimethyl 2-(4-aminophenyl)malonate and 4-(1-hydroxyethyl)-2,6-dimethoxyphenol in an inert gas atmosphere, adding dibutyl tin dilaurate, stirring, heating, and reacting to obtain modified steric phenol; mixing N,N-dimethylformamide, the modified steric phenol and di-tert-butyl chloromethyl phosphate, adding triethylamine, heating to reflux, stopping the reaction, washing, and drying to obtain a modified antioxidant; the plant oil-containing insulating oil prepared by the application has environmental protection, antioxidation and certain flame retardation, and is not prone to solidification at low temperature, these characteristics expand the application range of the insulating oil, and meet more strict application requirements.

Description

Technical Field

[0001] This invention relates to the field of lubricating oil technology, specifically to an insulating oil containing vegetable oil, its preparation method, and its application. Background Technology

[0002] Insulating oil is a type of lubricating oil, typically formulated from deeply refined lubricating oil base oils with the addition of antioxidants and other additives. It is frequently used as an important liquid insulating material. Insulating oils can be classified according to their raw materials: mineral oil-based insulating oils, vegetable oil-based insulating oils, and synthetic oil-based insulating oils. Mineral insulating oils are mainly derived from the refining process of natural petroleum, possessing excellent electrical insulation properties and cooling efficiency, and are relatively inexpensive. Vegetable oil insulating oils are renewable resources, and one of their biggest advantages compared to traditional mineral insulating oils is their superior biodegradability. In the natural environment, vegetable oil insulating oils can be decomposed by microorganisms, reducing pollution to soil and water bodies.

[0003] Chinese patent CN101619254A discloses a mixed insulating oil, which is obtained by mixing 15-25% vegetable oil with 75-85% mineral insulating oil and adding 0.2-0.5% antioxidant. However, the flash point of this insulating oil is around 145℃, limiting its application in high-fire-resistant environments. Chinese patent CN102682869A discloses a vegetable insulating oil and its preparation method, which involves reacting refined vegetable oil with low-molecular-weight alcohol under the action of a catalyst, removing impurities, adding antioxidants and pour point depressants, and mixing evenly to obtain the vegetable insulating oil. However, the insulating oil prepared by this invention has the problem of easily solidifying at low temperatures, limiting its applicability. Chinese patent CN101438356B discloses a plant-based electrical insulating oil and its preparation. The plant-based electrical insulating oil is obtained by esterification of a mixture of 40-50 parts by weight of soybean oil and 50-60 parts by weight of rapeseed oil with ethanol in the presence of an aluminosilicate catalyst. However, the oxidative stability of plant-based electrical insulating oils is relatively poor. Under high temperature and oxygen conditions, the polyunsaturated fatty acids in soybean oil and rapeseed oil are easily oxidized, leading to phenomena such as increased acid value, discoloration, and odor changes during long-term use, ultimately affecting electrical insulation performance and equipment safety. With the rapid development of national power equipment, the demand for insulating oil is increasing, and given the growing scarcity of petroleum resources, the demand for plant-based insulating oils is also rising.

[0004] In summary, developing a vegetable oil-based insulating oil that is not easily solidified at low temperatures, is flame-retardant, and has good antioxidant stability has significant practical importance and value. Summary of the Invention

[0005] To address the aforementioned technical problems, this invention provides an insulating oil containing vegetable oil, its preparation method, and its application.

[0006] To achieve the above objectives, the present invention provides a method for preparing an insulating oil containing vegetable oil, comprising the following steps:

[0007] Refined vegetable oil and alcohol are mixed, a catalyst is added, and the mixture is heated to react and obtain intermediate I. Intermediate I is then subjected to vacuum distillation, decolorization, and acid reduction to obtain intermediate II. Intermediate II, modified antioxidant, and pour point depressant are mixed, stirred, sonicated, and allowed to stand. The upper oil sample is then taken to obtain insulating oil containing vegetable oil.

[0008] The preparation method of the modified antioxidant includes the following steps:

[0009] Step (1) In an inert gas atmosphere, dimethyl 2-(4-aminophenyl)malonate and 4-(1-hydroxyethyl)-2,6-dimethoxyphenol were mixed evenly, dibutyltin dilaurate was added, stirred, heated and reacted. After the reaction was completed, the mixture was rotary evaporated to obtain the modified sterically hindered phenol.

[0010] Step (2) N,N-dimethylformamide, modified hindered phenol and di-tert-butylchloromethyl phosphate are mixed, triethylamine is added, the mixture is heated to reflux, the reaction is completed, washed and dried to obtain the modified antioxidant.

[0011] Preferably, the pour point depressant is an ethylene-vinyl acetate copolymer or a polymethacrylate copolymer.

[0012] Preferably, the mass ratio of intermediate II, modified antioxidant, and pour point depressant is 100:(0.2-0.4):(0.2-0.4).

[0013] Preferably, the acid-reducing agent is either silica gel or ethanolamine.

[0014] Preferably, the decolorizing agent is activated carbon.

[0015] Preferably, the vegetable oil is any one of soybean oil, peanut oil, cottonseed oil, palm oil, and coconut oil.

[0016] Preferably, the alcohol is an aliphatic straight-chain alcohol or a combination thereof with a carbon content of 8-16.

[0017] Preferably, the catalyst is one or a combination of two or more of sodium hydroxide, potassium hydroxide, and sodium methoxide.

[0018] Preferably, the mass ratio of vegetable oil, alcohol and catalyst is (25-45):(100-200):(0.5-0.9); the reaction temperature is 60-100℃ and the reaction time is 1-5h.

[0019] Preferably, in vacuum distillation, the pressure is 0.5-10 mmHg, the temperature is 80-100℃, and the time is 50-120 min.

[0020] Preferably, the mass ratio of dimethyl 2-(4-aminophenyl)malonate, 4-(1-hydroxyethyl)-2,6-dimethoxyphenol and dibutyltin dilaurate is (240-280):(140-180):(5-9); the reaction temperature is 130-150℃, and the reaction time is 3-5h.

[0021] Preferably, the mass ratio of N,N-dimethylformamide, modified hindered phenol, di-tert-butylchloromethyl phosphate and triethylamine is (2000-4000):(500-700):(200-240):(2-4); the reaction temperature is 140-150℃ and the reaction time is 6-10h.

[0022] Preferably, the insulating oil containing vegetable oil is prepared using the method described above.

[0023] Preferably, the insulating oil containing vegetable oil is used for insulation in electrical equipment.

[0024] Compared with the prior art, the beneficial effects of the present invention are as follows:

[0025] 1. In this invention, 4-(1-hydroxyethyl)-2,6-dimethoxyphenol possesses certain antioxidant properties. By linking it to dimethyl 2-(4-aminophenyl)malonate via transesterification, a synergistic effect exists between the hindered phenolic compound and dimethyl 2-(4-aminophenyl)malonate, enhancing the antioxidant effect. Furthermore, the amino group in the modified hindered phenol can react with the chlorine group in di-tert-butylchloromethyl phosphate to obtain a modified antioxidant. Simultaneously, di-tert-butylchloromethyl phosphate has a high flash point, and its phosphorus content increases flame retardant properties, thus expanding its application range.

[0026] 2. The vegetable oil used in this invention has good biodegradability, and vegetable oil insulating oil is a renewable resource. In the natural environment, vegetable oil insulating oil can be decomposed by microorganisms, reducing pollution to soil and water bodies. For example, in the event of an oil spill, vegetable oil insulating oil can be decomposed into harmless substances such as carbon dioxide and water in a short time, while mineral oil is difficult to degrade and will remain in the environment for a long time, causing serious damage to the ecosystem. In this invention, vegetable oil and alcohol are reacted, and then antioxidants and pour point depressants are added and mixed to obtain insulating oil containing vegetable oil. The modified antioxidant has a large molecular size and complex spatial structure. At low temperatures, this macromolecular structure can form a certain steric hindrance in the matrix material, hindering the regular arrangement and aggregation of vegetable oil molecules, thereby reducing crystallization and solidification, and improving the performance of vegetable oil in resisting solidification at low temperatures.

[0027] 3. The vegetable oil-containing insulating oil provided by this invention has excellent comprehensive performance and can be used in the same way as mineral oil; moreover, the preparation method is efficient, and it has a certain degree of flame retardancy, which expands the scope of application; at the same time, it has environmental protection characteristics, which meets the pursuit of sustainable development, making it an ideal alternative choice, thereby increasing the application of vegetable oil-based insulating oil in power equipment. Detailed Implementation

[0028] The technical solution of the present invention will be clearly and completely described below with reference to the embodiments. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0029] Example 1

[0030] This embodiment provides a method for preparing insulating oil containing vegetable oil, including the following steps:

[0031] Refined palm oil and octanol were mixed, sodium methoxide was added, and the mixture was heated to react at 60°C for 6 hours to obtain intermediate I. Intermediate I was then distilled under reduced pressure at 0.5 mmHg and 60°C for 120 minutes, followed by decolorization with 0.02 times the mass of activated carbon for 40 minutes. Ethanolamine was added to intermediate I and the mixture was stirred at 30 r / min for 140 minutes to obtain intermediate II. Intermediate II, modified antioxidant, and ethylene-vinyl acetate copolymer were mixed and stirred at room temperature and 40 r / min for 7 hours. The mixture was filtered, sonicated at 40 kHz for 2 minutes at room temperature, and allowed to stand at room temperature for 6 hours. The upper oil sample was then taken to obtain insulating oil containing vegetable oil.

[0032] The mass ratio of palm oil, octanol, and sodium methoxide is 25:100:0.5.

[0033] The mass ratio of intermediate II, modified antioxidant, and ethylene-vinyl acetate copolymer is 100:0.2:0.2.

[0034] The preparation method of the modified antioxidant includes the following steps:

[0035] Step (1) In an Ar atmosphere, dimethyl 2-(4-aminophenyl)malonate, 4-(1-hydroxyethyl)-2,6-dimethoxyphenol and dibutyltin dilaurate in a mass ratio of 240:140:5 were mixed and reacted at 130°C for 5 h. After the reaction was completed, the mixture was rotary evaporated to obtain the modified sterically hindered phenol.

[0036] Step (2) N,N-dimethylformamide, modified hindered phenol, di-tert-butylchloromethyl phosphate and triethylamine are mixed in a mass ratio of 2000:500:200:2 and heated under reflux at 140°C for 10 h. After the reaction is completed, the mixture is washed and dried at 50°C for 6 h to obtain the modified antioxidant.

[0037] Example 2

[0038] This embodiment provides a method for preparing insulating oil containing vegetable oil, including the following steps:

[0039] Refined palm oil and octanol were mixed, sodium methoxide was added, and the mixture was heated to react at 70°C for 4.5 h to obtain intermediate I. Intermediate I was then distilled under reduced pressure at 2.5 mmHg and 65°C for 105 min, followed by decolorization with 0.025 times the mass of activated carbon for 35 min. Ethanolamine was added to intermediate I and the mixture was stirred at 35 r / min for 130 min to obtain intermediate II. Intermediate II, modified antioxidant, and ethylene-vinyl acetate copolymer were mixed and stirred at room temperature and 45 r / min for 6.5 h. The mixture was filtered, sonicated at 40 kHz for 2 min at room temperature, and allowed to stand at room temperature for 6.5 h. The upper oil sample was then taken to obtain insulating oil containing vegetable oil.

[0040] The mass ratio of palm oil, octanol, and sodium methoxide is 30:125:0.6.

[0041] The mass ratio of intermediate II, modified antioxidant, and ethylene-vinyl acetate copolymer is 100:0.25:0.25.

[0042] The preparation method of the modified antioxidant includes the following steps:

[0043] Step (1) In an Ar atmosphere, dimethyl 2-(4-aminophenyl)malonate, 4-(1-hydroxyethyl)-2,6-dimethoxyphenol and dibutyltin dilaurate in a mass ratio of 250:150:6 were mixed and reacted at 135°C for 4.5 h. After the reaction was completed, the mixture was rotary evaporated to obtain the modified sterically hindered phenol.

[0044] Step (2) N,N-dimethylformamide, modified hindered phenol, di-tert-butylchloromethyl phosphate and triethylamine are mixed in a mass ratio of 2500:550:210:2.5 and heated under reflux at 142°C for 9 hours. After the reaction is complete, the mixture is washed and dried at 55°C for 5.5 hours to obtain the modified antioxidant.

[0045] Example 3

[0046] This embodiment provides a method for preparing insulating oil containing vegetable oil, including the following steps:

[0047] Refined palm oil and octanol were mixed, sodium methoxide was added, and the mixture was heated to react at 80°C for 3.5 h to obtain intermediate I. Intermediate I was then distilled under reduced pressure at 5 mmHg and 70°C for 90 min, followed by decolorization with 0.03 times the mass of activated carbon for 30 min. Ethanolamine was added to intermediate I and the mixture was stirred at 40 r / min for 120 min to obtain intermediate II. Intermediate II, modified antioxidant, and ethylene-vinyl acetate copolymer were mixed and stirred at room temperature and 50 r / min for 6 h. The mixture was filtered, sonicated at 40 kHz for 3 min at room temperature, and allowed to stand at room temperature for 7 h. The upper oil sample was then taken to obtain insulating oil containing vegetable oil.

[0048] The mass ratio of palm oil, octanol, and sodium methoxide is 35:150:0.7.

[0049] The mass ratio of intermediate II, modified antioxidant, and ethylene-vinyl acetate copolymer is 100:0.3:0.3.

[0050] The preparation method of the modified antioxidant includes the following steps:

[0051] Step (1) In an Ar atmosphere, dimethyl 2-(4-aminophenyl)malonate, 4-(1-hydroxyethyl)-2,6-dimethoxyphenol and dibutyltin dilaurate in a mass ratio of 260:160:7 were mixed and reacted at 140°C for 4 hours. After the reaction was completed, the mixture was rotary evaporated to obtain the modified sterically hindered phenol.

[0052] Step (2) N,N-dimethylformamide, modified hindered phenol, di-tert-butylchloromethyl phosphate and triethylamine are mixed in a mass ratio of 3000:600:220:3 and heated under reflux at 145°C for 8 hours. After the reaction is completed, the mixture is washed and dried at 60°C for 5 hours to obtain the modified antioxidant.

[0053] Example 4

[0054] This embodiment provides a method for preparing insulating oil containing vegetable oil, including the following steps:

[0055] Refined palm oil and octanol were mixed, sodium methoxide was added, and the mixture was heated to 90°C for 2.5 h to obtain intermediate I. Intermediate I was then distilled under reduced pressure at 8 mmHg and 75°C for 70 min, followed by decolorization with 0.035 times the mass of activated carbon for 25 min. Ethanolamine was added to intermediate I and the mixture was stirred at 45 r / min for 110 min to obtain intermediate II. Intermediate II, modified antioxidant, and ethylene-vinyl acetate copolymer were mixed and stirred at 55 r / min for 5.5 h at room temperature. The mixture was filtered, sonicated at 40 kHz for 4 min at room temperature, and allowed to stand at room temperature for 7.5 h. The upper oil sample was then taken to obtain insulating oil containing vegetable oil.

[0056] The mass ratio of palm oil, octanol, and sodium methoxide is 40:175:0.8.

[0057] The mass ratio of intermediate II, modified antioxidant, and ethylene-vinyl acetate copolymer is 100:0.35:0.35.

[0058] The preparation method of the modified antioxidant includes the following steps:

[0059] Step (1) In an Ar atmosphere, dimethyl 2-(4-aminophenyl)malonate, 4-(1-hydroxyethyl)-2,6-dimethoxyphenol and dibutyltin dilaurate in a mass ratio of 270:170:8 were mixed and reacted at 145°C for 3.5 h. After the reaction was completed, the mixture was rotary evaporated to obtain the modified sterically hindered phenol.

[0060] Step (2) N,N-dimethylformamide, modified hindered phenol, di-tert-butylchloromethyl phosphate and triethylamine are mixed in a mass ratio of 3500:650:230:3.5 and heated under reflux at 147°C for 7 hours. After the reaction is completed, the mixture is washed and dried at 55°C for 4.5 hours to obtain the modified antioxidant.

[0061] Example 5

[0062] This embodiment provides a method for preparing insulating oil containing vegetable oil, including the following steps:

[0063] Refined palm oil and octanol were mixed, sodium methoxide was added, and the mixture was heated to react at 100°C for 1 hour to obtain intermediate I. Intermediate I was then distilled under reduced pressure at 10 mmHg and 80°C for 50 minutes, followed by decolorization with 0.04 times the mass of activated carbon for 20 minutes. Ethanolamine was added to intermediate I and the mixture was stirred at 50 r / min for 100 minutes to obtain intermediate II. Intermediate II, modified antioxidant, and ethylene-vinyl acetate copolymer were mixed and stirred at 60 r / min for 5 hours at room temperature. The mixture was filtered, sonicated at 40 kHz for 4 minutes at room temperature, and allowed to stand at room temperature for 8 hours. The upper oil sample was then taken to obtain insulating oil containing vegetable oil.

[0064] The mass ratio of palm oil, octanol, and sodium methoxide is 45:200:0.9.

[0065] The mass ratio of intermediate II, modified antioxidant, and ethylene-vinyl acetate copolymer is 100:0.4:0.4.

[0066] The preparation method of the modified antioxidant includes the following steps:

[0067] Step (1) In an Ar atmosphere, dimethyl 2-(4-aminophenyl)malonate, 4-(1-hydroxyethyl)-2,6-dimethoxyphenol and dibutyltin dilaurate in a mass ratio of 280:180:9 were mixed and reacted at 150°C for 3 hours. After the reaction was completed, the mixture was rotary evaporated to obtain the modified sterically hindered phenol.

[0068] Step (2) N,N-dimethylformamide, modified hindered phenol, di-tert-butylchloromethyl phosphate and triethylamine are mixed in a mass ratio of 4000:700:240:4 and heated under reflux at 150°C for 6 hours. After the reaction is completed, the mixture is washed and dried at 50°C for 4 hours to obtain the modified antioxidant.

[0069] Comparative Example 1

[0070] This comparative example provides a method for preparing an insulating oil containing vegetable oil, comprising the following steps:

[0071] Refined palm oil and octanol were mixed, sodium methoxide was added, and the mixture was heated to react at 60°C for 6 hours to obtain intermediate I. Intermediate I was then distilled under reduced pressure at 0.5 mmHg and 60°C for 120 minutes, followed by decolorization with 0.02 times the mass of activated carbon for 40 minutes. Ethanolamine was added to intermediate I and the mixture was stirred at 30 r / min for 140 minutes to obtain intermediate II. Intermediate II, modified antioxidant, and ethylene-vinyl acetate copolymer were mixed and stirred at room temperature and 40 r / min for 7 hours. The mixture was filtered, sonicated at 40 kHz for 2 minutes at room temperature, and allowed to stand at room temperature for 6 hours. The upper oil sample was then taken to obtain insulating oil containing vegetable oil.

[0072] The mass ratio of palm oil, octanol, and sodium methoxide is 25:100:0.5.

[0073] The mass ratio of intermediate II, modified antioxidant, and ethylene-vinyl acetate copolymer is 100:0.2:0.2.

[0074] The preparation method of the modified antioxidant includes the following steps:

[0075] In an Ar atmosphere, dimethyl 2-(4-aminophenyl)malonate, 4-(1-hydroxyethyl)-2,6-dimethoxyphenol and dibutyltin dilaurate were mixed in a mass ratio of 240:140:5 and reacted at 130°C for 5 h. After the reaction was completed, the mixture was rotary evaporated to obtain the modified antioxidant.

[0076] Comparative Example 2

[0077] This comparative example is the vegetable insulating oil composition 2# disclosed in Example 10 of Chinese patent application CN109337739B.

[0078] The insulating oils prepared in Examples 1-5 and Comparative Examples 1-2 were subjected to relevant tests. The flash point was determined according to GB / T 3536-2008; the pour point was determined according to GB / T 510. Biodegradability determination: Soil degradation experiments were conducted in 50-day cycles. Specifically, soil samples with no prior pollution records were taken using a core sampler (e.g., a stainless steel tube approximately 3 cm in diameter). The sampler was inserted approximately 15 cm into the soil near a large tree to extract the soil sample. The soil samples were refrigerated before the experiment. 100 g of soil sample was placed in a wide-mouthed glass bottle, with 5 g of liquid insulating medium added per 100 g of soil. The experiment was conducted at a constant temperature of 25°C, using an unsealed method to facilitate the release of exhaled CO2, gas exchange with the external environment, and to maintain the original soil moisture. The hydrocarbon content in the samples before and after the experiment was measured using a UV spectrophotometer to represent the residual amount of liquid insulating medium in the soil. The biodegradability rate of the liquid insulating medium was determined by the absorption spectra before and after the experiment. The testing instrument could be a UV-1601 Shimadzu multi-functional spectrometer with a wavelength range of 200-800 nm, and anhydrous ethanol was used as the reference solution. Specific test results are shown in Table 1.

[0079] Table 1

[0080]

[0081] As shown in Table 1 above, the insulating oils prepared in Examples 1-5 have good flame retardancy and biodegradability, and are not easily solidified at low temperatures. Their overall performance is better than that of Comparative Examples 1-2, and these properties further increase their applicability.

[0082] Although embodiments of the present invention have been shown and described, it will be understood by those skilled in the art that various changes, modifications, substitutions and variations can be made to these embodiments without departing from the principles and spirit of the present invention. All equivalent changes and improvements made within the scope of the present invention should still fall within the patent coverage of the present invention.

Claims

1. A method for preparing an insulating oil containing vegetable oil, characterized in that, Includes the following steps: Refined vegetable oil and alcohol are mixed, a catalyst is added, and the mixture is heated to react and obtain intermediate I. Intermediate I is then subjected to vacuum distillation, decolorization, and acid reduction to obtain intermediate II. Intermediate II, modified antioxidant, and pour point depressant are mixed, stirred, sonicated, and allowed to stand. The upper oil sample is then taken to obtain insulating oil containing vegetable oil. The preparation method of the modified antioxidant includes the following steps: Step (1) In an inert gas atmosphere, dimethyl 2-(4-aminophenyl)malonate and 4-(1-hydroxyethyl)-2,6-dimethoxyphenol were mixed evenly, dibutyltin dilaurate was added, stirred, heated and reacted. After the reaction was completed, the mixture was rotary evaporated to obtain the modified sterically hindered phenol. Step (2) N,N-dimethylformamide, modified hindered phenol and di-tert-butylchloromethyl phosphate are mixed, triethylamine is added, the mixture is heated to reflux, the reaction is completed, washed and dried to obtain the modified antioxidant.

2. The method for preparing an insulating oil containing vegetable oil according to claim 1, characterized in that, Vegetable oil is any one of soybean oil, peanut oil, cottonseed oil, palm oil, and coconut oil.

3. The method for preparing an insulating oil containing vegetable oil according to claim 1, characterized in that, The alcohol is an aliphatic straight-chain alcohol or a combination thereof with a carbon content of 8-16.

4. The method for preparing an insulating oil containing vegetable oil according to claim 1, characterized in that, The catalyst is one or a combination of two or more of sodium hydroxide, potassium hydroxide, and sodium methoxide.

5. The method for preparing an insulating oil containing vegetable oil according to claim 1, characterized in that, The mass ratio of vegetable oil, alcohol and catalyst is (25-45):(100-200):(0.5-0.9); the reaction temperature is 60-100℃ and the reaction time is 1-5h.

6. The method for preparing an insulating oil containing vegetable oil according to claim 1, characterized in that, In vacuum distillation, the pressure is 0.5-10 mmHg, the temperature is 80-100℃, and the time is 50-120 min.

7. The method for preparing an insulating oil containing vegetable oil according to claim 1, characterized in that, The mass ratio of dimethyl 2-(4-aminophenyl)malonate, 4-(1-hydroxyethyl)-2,6-dimethoxyphenol and dibutyltin dilaurate is (240-280):(140-180):(5-9); the reaction temperature is 130-150℃ and the reaction time is 3-5h.

8. The method for preparing an insulating oil containing vegetable oil according to claim 1, characterized in that, The mass ratio of N,N-dimethylformamide, modified hindered phenol, di-tert-butylchloromethyl phosphate and triethylamine is (2000-4000):(500-700):(200-240):(2-4); the reaction temperature is 140-150℃ and the reaction time is 6-10h.

9. An insulating oil containing vegetable oil prepared by the method for preparing insulating oil containing vegetable oil according to any one of claims 1-8.

10. An application of the insulating oil containing vegetable oil as described in claim 9 in the insulation of electrical equipment.

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