High-antioxidant plant oil-based transformer insulating oil and preparation method thereof
By using a combination of grafted titanium dioxide and microencapsulated antioxidants in vegetable oil-based transformer insulating oil, the problems of insufficient thermal conductivity and antioxidant capacity were solved, achieving efficient self-repair and stable operation, and improving electrical performance.
Patent Information
- Application Number
- CN202511077653.4
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-08-01
- Publication Date
- 2025-11-11
AI Technical Summary
Existing vegetable oil-based transformer insulating oils have shortcomings in terms of thermal conductivity, antioxidant capacity, and self-healing mechanism, leading to unstable equipment operation and environmental pollution.
The surface of grafted titanium dioxide is grafted with dendritic polyamide amine, combined with microencapsulated antioxidants and metal passivators to enhance dispersion performance and thermal conductivity, and achieve self-healing through a dynamic equilibrium mechanism.
It significantly improves the thermal conductivity and antioxidant capacity of vegetable oil-based transformer insulating oil, reduces viscosity, and extends the electrical performance stability and service life of the product.
Smart Images
Figure CN120924337A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of vegetable oil-based transformer insulating oil technology, and in particular to a high antioxidant vegetable oil-based transformer insulating oil and its preparation method. Background Technology
[0002] With the continuous growth of power grid load, transformers are rapidly developing towards higher voltage levels and larger capacities, placing more stringent requirements on the performance of insulating oil. While traditional mineral insulating oils possess excellent thermal conductivity and oxidation stability, their sulfur-containing components (such as thiophene compounds) can react with copper windings during operation to form conductive cuprous sulfides, leading to carbonization of the insulating paper and even inter-turn short circuits, seriously threatening the safe operation of the power grid. Furthermore, mineral oils have a biodegradability rate of less than 30%, and leaks can easily cause soil and water pollution.
[0003] Plant-based insulating oils have become a research hotspot due to their renewability and environmental advantages. These insulating oils, mainly composed of triglycerides, have high flash points, high breakdown voltages, and good biodegradability. However, plant-based oils still face three major technical bottlenecks in practical applications: (1) Defects in thermal conductivity: Plant-based oils have longer molecular chains and significantly higher kinematic viscosity than mineral oils, resulting in reduced heat transfer efficiency. Under heavy load conditions, increased oil temperature will accelerate oxidation and corrode equipment; (2) Insufficient antioxidant capacity: Unsaturated double bonds in plant-based oils are easily attacked by oxygen, and existing antioxidants are unable to form a stable protective layer; (3) Lack of self-repair mechanism: Mineral oils can achieve reversible removal of deterioration products through adsorbents, but polar substances generated during operation will continue to accumulate, eventually requiring complete replacement.
[0004] Current technologies primarily rely on composite antioxidant systems to delay oxidation, but the effects are not significant. Developing vegetable oil-based insulating oils that combine high thermal conductivity, long-lasting antioxidant properties, and self-healing capabilities has become a key direction in power equipment reliability research. Summary of the Invention
[0005] The purpose of this invention is to address the shortcomings of existing technologies by proposing a high-antioxidant vegetable oil-based transformer insulating oil and its preparation method.
[0006] A high-antioxidant vegetable oil-based transformer insulating oil, the raw materials of which include, by weight: 35-50 parts vegetable oil, 1-6 parts grafted titanium dioxide, 1-3 parts isocyanate, 5-15 parts liquid paraffin, 1-2 parts chitosan, 1-5 parts antioxidant, 1-2 parts emulsifier, 0.1-0.5 parts curing agent, 1-2 parts metal passivator, 1-2 parts diphenyl toluene phosphate, and 1-5 parts alkylphenol polyoxyethylene ether.
[0007] Preferably, the vegetable oil is at least one of palm oil, rapeseed oil, and coconut oil. The acid value of the palm oil is 0.02-0.05 mg KOH / g.
[0008] Preferably, the antioxidant includes 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-methylphenol; the mass ratio of 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-methylphenol is 1:0.1-0.5.
[0009] Preferably, the emulsifier is at least one of sorbitan monooleate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, and sorbitan tristearate.
[0010] Preferably, the curing agent is amine 105 curing agent or triethylamine.
[0011] Preferably, the metal passivating agent is benzotriazole or / and 5-methylbenzotriazole.
[0012] Preferably, the grafted titanium dioxide is prepared by the following steps: nano-titanium dioxide particles and dodecyltrimethoxysilane are added to an ethanol aqueous solution and ultrasonically treated for 1-2 hours, dendritic polyamide amine is added, the temperature is raised to 80-85℃, stirred for 10-20 minutes, ultrasonically treated for 1-2 hours, centrifuged, washed with ethanol, and vacuum dried.
[0013] More preferably, the mass ratio of nano-titanium dioxide particles, dodecyltrimethoxysilane, and dendritic polyamide amine is 1-6:0.01-0.1:0.1-1.
[0014] More preferably, after the nano-titanium dioxide particles are added to the ethanol aqueous solution, the ultrasonic treatment frequency is 70-90 kHz; after heating to 80-85℃, the ultrasonic treatment frequency is 70-80 kHz.
[0015] The preparation method of the above-mentioned high antioxidant vegetable oil-based transformer insulating oil includes the following steps:
[0016] S1. Mix the antioxidant, isocyanate, and liquid paraffin evenly to obtain a pretreated antioxidant;
[0017] Chitosan was added to an acetic acid solution and stirred until homogeneous. Then an emulsifier was added and stirred until homogeneous. A pretreated antioxidant was added dropwise while stirring at high speed. Stirring was continued for 20-50 minutes. A curing agent was added and stirred at 50-60°C for 10-20 hours. The mixture was cooled to room temperature, filtered, washed, and vacuum dried to obtain the microencapsulated antioxidant.
[0018] S2. Vacuum filter the vegetable oil, add microencapsulated antioxidant and grafted titanium dioxide, stir at 50-70℃ for 10-30 min, add metal passivator, toluene diphenyl phosphate and alkylphenol polyoxyethylene ether and continue stirring for 5-15 min, sonicate for 10-20 min, and vacuum dry.
[0019] Beneficial effects:
[0020] This invention grafts dendritic polyamide amine onto the surface of grafted titanium dioxide, which can significantly enhance the dispersion performance of vegetable oil and microencapsulated antioxidants, reduce the viscosity of transformer oil, and ensure uniform dispersion of all materials. By enhancing the thermal conductivity path through the high specific surface area of nano-titanium dioxide, the thermal conductivity and electrical properties of transformer oil are greatly improved.
[0021] This invention utilizes the synergistic effect of 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-methylphenol to stabilize unsaturated double bonds, while the microencapsulated structure slows down the consumption rate of antioxidants. Toluene diphenyl phosphate, as an auxiliary antioxidant, works with metal passivators (such as benzotriazole) to block the chain reaction of metal ion-catalyzed oxidation, thereby comprehensively enhancing the antioxidant performance of the product.
[0022] This invention modifies the surface of grafted titanium dioxide with dodecyltrimethoxysilane, which can adsorb polar degradation products. Meanwhile, the amino groups on the surface of dendritic polyamide amine can undergo a reversible reaction with the carboxylic acid generated by oxidation in vegetable oil to form a dynamic equilibrium. Combined with the slow-release of microencapsulated antioxidants, it continuously repairs local oxidized areas and achieves self-sustaining operation. Even after high-temperature aging, it can effectively reduce the trend of electrical degradation. Attached Figure Description
[0023] Figure 1 The image shows a comparison of the flash point and breakdown voltage of the vegetable oil-based transformer insulating oils obtained in Example 5 and Comparative Examples 1-3.
[0024] Figure 2 This is a comparison chart of the dielectric loss factors of the vegetable oil-based transformer insulating oils obtained in Example 5 and Comparative Examples 1-3.
[0025] Figure 3 This is a comparison chart of the acid values of the vegetable oil-based transformer insulating oils obtained in Example 5 and Comparative Examples 1-3 after aging.
[0026] Figure 4 This is a comparison chart of the breakdown voltage change rate and dielectric loss factor change rate of the vegetable oil-based transformer insulating oils obtained in Example 5 and Comparative Examples 1-3 after aging. Detailed Implementation
[0027] The present invention will be further explained below with reference to specific embodiments.
[0028] The palm oil used below has an acid value of 0.03 mg KOH / g and a kinematic viscosity of 55 mmHg at 40°C. 2 / s.
[0029] Example 1
[0030] A high-antioxidant vegetable oil-based transformer insulating oil, the raw materials of which include: 350g palm oil, 10g grafted titanium dioxide, 10g isophorone diisocyanate, 50g liquid paraffin, 10g chitosan, 10g antioxidant, 10g Span 80, 1g amine 105 curing agent, 5g benzotriazole, 5g 5-methylbenzotriazole, 10g toluene diphenyl phosphate, and 10g OP-10.
[0031] The antioxidant is composed of 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-methylphenol in a mass ratio of 1:0.1.
[0032] The grafted titanium dioxide was prepared by the following steps: 10g of nano titanium dioxide particles and 0.1g of dodecyltrimethoxysilane were added to 50g of 50% ethanol aqueous solution and ultrasonically treated for 1h at a frequency of 70kHz. Then, 1g of dendritic polyamide amine was added, the temperature was raised to 80℃, and the mixture was stirred at 1000r / min for 10min. The mixture was ultrasonically treated for 1h at a frequency of 70kHz, centrifuged, washed with ethanol, and vacuum dried.
[0033] The preparation method of the above-mentioned high antioxidant vegetable oil-based transformer insulating oil includes the following steps:
[0034] S1. Mix the antioxidant, isophorone diisocyanate, and liquid paraffin evenly to obtain a pretreated antioxidant;
[0035] Chitosan was added to 400g of 1% acetic acid solution and stirred until homogeneous. Span 80 was then added and stirred until homogeneous. Pretreated antioxidant was added dropwise under high-speed stirring at 1000r / min. Stirring continued for 20min. The stirring speed was reduced to 100r / min, and amine 105 curing agent was added. The mixture was stirred at 50℃ for 10h. After cooling to room temperature, the mixture was filtered, washed, and vacuum dried to obtain the microencapsulated antioxidant.
[0036] S2. Vacuum filter the vegetable oil, add microencapsulated antioxidant and grafted titanium dioxide, stir at 50℃ for 10 min at a stirring speed of 50 r / min, add benzotriazole, 5-methylbenzotriazole, toluene diphenyl phosphate and OP-10 and continue stirring for 5 min, sonicate for 10 min at a sonic frequency of 500 W, and vacuum dry.
[0037] Example 2
[0038] A high-antioxidant vegetable oil-based transformer insulating oil, the raw materials of which include: 500g palm oil, 60g grafted titanium dioxide, 30g isophorone diisocyanate, 150g liquid paraffin, 20g chitosan, 50g antioxidant, 20g Span 80, 5g amine 105 curing agent, 15g benzotriazole, 5g 5-methylbenzotriazole, 20g toluene diphenyl phosphate, and 50g OP-10.
[0039] The antioxidant is composed of 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-methylphenol in a mass ratio of 1:0.5.
[0040] The grafted titanium dioxide was prepared by the following steps: 60g of nano titanium dioxide particles and 1g of dodecyltrimethoxysilane were added to 150g of 60% ethanol aqueous solution and ultrasonically treated for 2h at a frequency of 90kHz. Then, 10g of dendritic polyamide amine was added, the temperature was raised to 85℃, and the mixture was stirred at 2000r / min for 20min. The mixture was ultrasonically treated for 2h at a frequency of 80kHz, centrifuged, washed with ethanol, and vacuum dried.
[0041] The preparation method of the above-mentioned high antioxidant vegetable oil-based transformer insulating oil includes the following steps:
[0042] S1. Mix the antioxidant, isophorone diisocyanate, and liquid paraffin evenly to obtain a pretreated antioxidant;
[0043] Chitosan was added to 600g of 2% acetic acid solution and stirred until homogeneous. Span 80 was then added and stirred until homogeneous. Pretreated antioxidant was added dropwise under high-speed stirring at 2000r / min. Stirring was continued for 50min. The stirring speed was reduced to 400r / min and amine 105 curing agent was added. The mixture was stirred at 60℃ for 20h. After cooling to room temperature, the mixture was filtered, washed, and vacuum dried to obtain microencapsulated antioxidant.
[0044] S2. Vacuum filter the vegetable oil, add microencapsulated antioxidant and grafted titanium dioxide, stir at 70℃ for 30 min at a stirring speed of 150 r / min, add benzotriazole, 5-methylbenzotriazole, toluene diphenyl phosphate and OP-10 and continue stirring for 15 min, sonicate for 20 min at a sonic frequency of 1000 W, and vacuum dry.
[0045] Example 3
[0046] A high-antioxidant vegetable oil-based transformer insulating oil, the raw materials of which include: 400g palm oil, 50g grafted titanium dioxide, 15g isophorone diisocyanate, 120g liquid paraffin, 13g chitosan, 40g antioxidant, 12g Span 80, 4g amine 105 curing agent, 12g 5-methylbenzotriazole, 18g toluene diphenyl phosphate, and 20g OP-10.
[0047] The antioxidant is composed of 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-methylphenol in a mass ratio of 1:0.4.
[0048] The grafted titanium dioxide was prepared by the following steps: 20g of nano titanium dioxide particles and 0.7g of dodecyltrimethoxysilane were added to 80g of 58% ethanol aqueous solution and ultrasonically treated for 80min at a frequency of 85kHz. Then, 2g of dendritic polyamide amine was added, the temperature was raised to 83℃, and the mixture was stirred at 1200r / min for 17min. The mixture was ultrasonically treated for 80min at a frequency of 78kHz, centrifuged, washed with ethanol, and vacuum dried.
[0049] The preparation method of the above-mentioned high antioxidant vegetable oil-based transformer insulating oil includes the following steps:
[0050] S1. Mix the antioxidant, isophorone diisocyanate, and liquid paraffin evenly to obtain a pretreated antioxidant;
[0051] Chitosan was added to 450g of 1.7% acetic acid solution and stirred until homogeneous. Span 80 was then added and stirred until homogeneous. Pretreated antioxidant was added dropwise under high-speed stirring at 1200r / min. Stirring continued for 40min. The stirring speed was reduced to 200r / min, and amine 105 curing agent was added. The mixture was stirred at 58℃ for 12h. After cooling to room temperature, the mixture was filtered, washed, and vacuum dried to obtain microencapsulated antioxidant.
[0052] S2. Vacuum filter the vegetable oil, add microencapsulated antioxidant and grafted titanium dioxide, stir at 65℃ for 15 min at a stirring speed of 120 r / min, add 5-methylbenzotriazole, toluene diphenyl phosphate and OP-10 and continue stirring for 8 min, sonicate for 18 min at a sonic frequency of 700 W, and vacuum dry.
[0053] Example 4
[0054] A high-antioxidant vegetable oil-based transformer insulating oil, the raw materials of which include: 480g palm oil, 20g grafted titanium dioxide, 25g isophorone diisocyanate, 80g liquid paraffin, 17g chitosan, 20g antioxidant, 18g Span 80, 2g amine 105 curing agent, 18g 5-methylbenzotriazole, 12g toluene diphenyl phosphate, and 40g OP-10.
[0055] The antioxidant is composed of 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-methylphenol in a mass ratio of 1:0.2.
[0056] The grafted titanium dioxide was prepared by the following steps: 50g of nano titanium dioxide particles and 0.3g of dodecyltrimethoxysilane were added to 120g of 52% ethanol aqueous solution and ultrasonically treated for 100min at a frequency of 75kHz. Then, 8g of dendritic polyamide amine was added, the temperature was raised to 81℃, and the mixture was stirred at 1800r / min for 13min. The mixture was ultrasonically treated for 100min at a frequency of 72kHz, centrifuged, washed with ethanol, and vacuum dried.
[0057] The preparation method of the above-mentioned high antioxidant vegetable oil-based transformer insulating oil includes the following steps:
[0058] S1. Mix the antioxidant, isophorone diisocyanate, and liquid paraffin evenly to obtain a pretreated antioxidant;
[0059] Chitosan was added to 550g of 1.3% acetic acid solution and stirred until homogeneous. Span 80 was then added and stirred until homogeneous. Pretreated antioxidant was added dropwise under high-speed stirring at 1800r / min. Stirring continued for 30min. The stirring speed was reduced to 300r / min, and amine 105 curing agent was added. The mixture was stirred at 52℃ for 18h. After cooling to room temperature, the mixture was filtered, washed, and vacuum dried to obtain microencapsulated antioxidant.
[0060] S2. Vacuum filter the vegetable oil, add microencapsulated antioxidant and grafted titanium dioxide, stir at 55℃ for 25 min at a stirring speed of 80 r / min, add 5-methylbenzotriazole, toluene diphenyl phosphate and OP-10 and continue stirring for 12 min, sonicate for 12 min at a sonic frequency of 900 W, and vacuum dry.
[0061] Example 5
[0062] A high-antioxidant vegetable oil-based transformer insulating oil, the raw materials of which include: 450g palm oil, 40g grafted titanium dioxide, 20g isophorone diisocyanate, 100g liquid paraffin, 15g chitosan, 30g antioxidant, 15g Span 80, 3g amine 105 curing agent, 15g benzotriazole, 15g toluene diphenyl phosphate, and 30g OP-10.
[0063] The antioxidant is composed of 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-methylphenol in a mass ratio of 1:0.3.
[0064] The grafted titanium dioxide was prepared by the following steps: 35g of nano titanium dioxide particles and 0.5g of dodecyltrimethoxysilane were added to 100g of 55% ethanol aqueous solution and ultrasonically treated for 90min at a frequency of 80kHz. Then, 5g of dendritic polyamide amine was added, the temperature was raised to 82℃, and the mixture was stirred at 1500r / min for 15min. The mixture was ultrasonically treated for 90min at a frequency of 75kHz, centrifuged, washed with ethanol, and vacuum dried.
[0065] The preparation method of the above-mentioned high antioxidant vegetable oil-based transformer insulating oil includes the following steps:
[0066] S1. Mix the antioxidant, isophorone diisocyanate, and liquid paraffin evenly to obtain a pretreated antioxidant;
[0067] Chitosan was added to 500g of 1.5% acetic acid solution and stirred until homogeneous. Span 80 was then added and stirred until homogeneous. Pretreated antioxidant was added dropwise under high-speed stirring at 1500r / min. Stirring continued for 35min. The stirring speed was reduced to 250r / min, and amine 105 curing agent was added. The mixture was stirred at 55℃ for 15h. After cooling to room temperature, the mixture was filtered, washed, and vacuum dried to obtain microencapsulated antioxidant.
[0068] S2. Vacuum filter the vegetable oil, add microencapsulated antioxidant and grafted titanium dioxide, stir at 60℃ for 20 min at a stirring speed of 100 r / min, add benzotriazole, toluene diphenyl phosphate and OP-10 and continue stirring for 10 min, sonicate for 15 min at a sonic frequency of 800 W, and vacuum dry.
[0069] Comparative Example 1
[0070] A high-antioxidant vegetable oil-based transformer insulating oil, the raw materials of which include: 450g palm oil, 40g grafted titanium dioxide, 20g isophorone diisocyanate, 100g liquid paraffin, 15g chitosan, 30g antioxidant, 15g Span 80, 3g amine 105 curing agent, 15g benzotriazole, 15g toluene diphenyl phosphate, and 30g OP-10.
[0071] The antioxidant is composed of 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-methylphenol in a mass ratio of 1:0.3.
[0072] The grafted titanium dioxide was prepared by the following steps: 35g of nano titanium dioxide particles and 0.5g of dodecyltrimethoxysilane were added to 100g of 55% ethanol aqueous solution and ultrasonically treated for 90min at a frequency of 80kHz. After centrifugation, the mixture was washed with ethanol and vacuum dried.
[0073] The preparation method of the above-mentioned high antioxidant vegetable oil-based transformer insulating oil includes the following steps:
[0074] S1. Mix the antioxidant, isophorone diisocyanate, and liquid paraffin evenly to obtain a pretreated antioxidant;
[0075] Chitosan was added to 500g of 1.5% acetic acid solution and stirred until homogeneous. Span 80 was then added and stirred until homogeneous. Pretreated antioxidant was added dropwise under high-speed stirring at 1500r / min. Stirring continued for 35min. The stirring speed was reduced to 250r / min, and amine 105 curing agent was added. The mixture was stirred at 55℃ for 15h. After cooling to room temperature, the mixture was filtered, washed, and vacuum dried to obtain microencapsulated antioxidant.
[0076] S2. Vacuum filter the vegetable oil, add microencapsulated antioxidant and grafted titanium dioxide, stir at 60℃ for 20 min at a stirring speed of 100 r / min, add benzotriazole, toluene diphenyl phosphate and OP-10 and continue stirring for 10 min, sonicate for 15 min at a sonic frequency of 800 W, and vacuum dry.
[0077] Comparative Example 2
[0078] A high-antioxidant vegetable oil-based transformer insulating oil, the raw materials of which include: 450g palm oil, 40g nano titanium dioxide, 20g isophorone diisocyanate, 100g liquid paraffin, 15g chitosan, 30g antioxidant, 15g Span 80, 3g amine 105 curing agent, 15g benzotriazole, 15g toluene diphenyl phosphate, and 30g OP-10.
[0079] The antioxidant is composed of 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-methylphenol in a mass ratio of 1:0.3.
[0080] The preparation method of the above-mentioned high antioxidant vegetable oil-based transformer insulating oil includes the following steps:
[0081] S1. Mix the antioxidant, isophorone diisocyanate, and liquid paraffin evenly to obtain a pretreated antioxidant;
[0082] Chitosan was added to 500g of 1.5% acetic acid solution and stirred until homogeneous. Span 80 was then added and stirred until homogeneous. Pretreated antioxidant was added dropwise under high-speed stirring at 1500r / min. Stirring continued for 35min. The stirring speed was reduced to 250r / min, and amine 105 curing agent was added. The mixture was stirred at 55℃ for 15h. After cooling to room temperature, the mixture was filtered, washed, and vacuum dried to obtain microencapsulated antioxidant.
[0083] S2. Vacuum filter the vegetable oil, add microencapsulated antioxidant and nano titanium dioxide, stir at 60℃ for 20 minutes at a stirring speed of 100 r / min, add benzotriazole, toluene diphenyl phosphate and OP-10 and continue stirring for 10 minutes, sonicate for 15 minutes at a sonic frequency of 800 W, and vacuum dry.
[0084] Comparative Example 3
[0085] A high-antioxidant vegetable oil-based transformer insulating oil, the raw materials of which include: 450g palm oil, 40g grafted titanium dioxide, 20g isophorone diisocyanate, 100g liquid paraffin, 15g chitosan, 30g antioxidant, 15g Span 80, 3g amine 105 curing agent, 15g benzotriazole, 15g toluene diphenyl phosphate, and 30g OP-10.
[0086] The antioxidant is composed of 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-methylphenol in a mass ratio of 1:0.3.
[0087] The grafted titanium dioxide was prepared by the following steps: 35g of nano titanium dioxide particles and 0.5g of dodecyltrimethoxysilane were added to 100g of 55% ethanol aqueous solution and ultrasonically treated for 90min at a frequency of 80kHz. Then, 5g of dendritic polyamide amine was added, the temperature was raised to 82℃, and the mixture was stirred at 1500r / min for 15min. The mixture was ultrasonically treated for 90min at a frequency of 75kHz, centrifuged, washed with ethanol, and vacuum dried.
[0088] The preparation method of the above-mentioned high antioxidant vegetable oil-based transformer insulating oil includes the following steps:
[0089] S1. Mix the antioxidant, isophorone diisocyanate, and liquid paraffin evenly to obtain a pretreated antioxidant;
[0090] Span 80 was added to 500g of 1.5% acetic acid solution and stirred until homogeneous. Pretreated antioxidant was added dropwise while stirring at a high speed of 1500r / min. Stirring continued for 35min. The stirring speed was reduced to 250r / min, and amine 105 curing agent was added. The mixture was stirred at 55℃ for 15h, cooled to room temperature, filtered, washed, and vacuum dried to obtain microencapsulated antioxidant.
[0091] S2. Vacuum filter the vegetable oil, add microencapsulated antioxidant and grafted titanium dioxide, stir at 60℃ for 20 min at a stirring speed of 100 r / min, add benzotriazole, toluene diphenyl phosphate and OP-10 and continue stirring for 10 min, sonicate for 15 min at a sonic frequency of 800 W, and vacuum dry.
[0092] The flash point of the vegetable oil-based transformer insulating oils obtained in Example 5 and Comparative Examples 1-3 was determined according to GB / T 3536-2008 "Determination of Flash Point and Ignition Point of Petroleum Products - Cleveland Open Cup Method". The breakdown voltage of the vegetable oil-based transformer insulating oils obtained in Example 5 and Comparative Examples 1-3 was determined according to GB / T 507-2002 "Determination of Breakdown Voltage of Insulating Oil".
[0093] like Figure 1 As shown, the vegetable oil-based transformer insulating oil obtained in Example 5 had the highest flash point and breakdown voltage, which were superior to those of Comparative Examples 1-3 (P<0.05).
[0094] The dielectric loss factor of the vegetable oil-based transformer insulating oils obtained in Example 5 and Comparative Examples 1-3 was determined in accordance with GB / T 5654-2007 "Measurement of Relative Permittivity, Dielectric Loss Factor and DC Resistivity of Liquid Insulating Materials".
[0095] like Figure 2 As shown, the vegetable oil-based transformer insulating oil obtained in Example 5 has the lowest dielectric loss factor, which is better than that of Comparative Examples 1-3 (P<0.05).
[0096] The vegetable oil-based transformer insulating oils obtained in Example 5 and Comparative Examples 1-3 were placed in an aging chamber with the same environmental conditions. The temperature of the aging chamber was set to 100°C and the aging test period was 30 days. The acid value, breakdown voltage and dielectric loss factor of each group of samples were tested, and the aging change rate of breakdown voltage and dielectric loss factor was calculated.
[0097] like Figure 3 As shown, the vegetable oil-based transformer insulating oil obtained in Example 5 had the lowest acid value after aging, which was superior to Comparative Examples 1-3 (P < 0.05). Figure 4 As shown, the vegetable oil-based transformer insulating oil obtained in Example 5 had the smallest rate of change in breakdown voltage and dielectric loss factor after aging, which was better than that of Comparative Examples 1-3 (P<0.05).
[0098] The reason for the above results is that the present invention grafts dendritic polyamide amine onto the surface of grafted titanium dioxide, which can significantly enhance the dispersion performance of vegetable oil and microencapsulated antioxidants, reduce the viscosity of transformer oil, and ensure uniform dispersion of all materials. The high specific surface area of nano-titanium dioxide enhances the thermal conductivity pathway, greatly improving the thermal conductivity and electrical properties of the transformer oil. The present invention utilizes the synergistic effect of 2,6-di-tert-butyl-p-cresol and 2,6-di-tert-butyl-4-methylphenol to stabilize unsaturated double bonds, while the microencapsulation structure slows down the antioxidant consumption rate. Toluene diphenyl phosphate, as an auxiliary antioxidant, works with benzotriazole to block the metal ion-catalyzed oxidation chain reaction, comprehensively enhancing the product's antioxidant performance. This invention modifies the surface of grafted titanium dioxide with dodecyltrimethoxysilane, which can adsorb polar degradation products. Meanwhile, the amino groups on the surface of dendritic polyamide amine can undergo a reversible reaction with the carboxylic acid generated by oxidation in vegetable oil to form a dynamic equilibrium. Combined with the slow-release of microencapsulated antioxidants, it continuously repairs local oxidized areas and achieves self-sustaining operation. Even after high-temperature aging, it can effectively reduce the trend of electrical degradation.
[0099] The above description is only a preferred embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any equivalent substitutions or modifications made by those skilled in the art within the scope of the technology disclosed in the present invention, based on the technical solution and inventive concept of the present invention, should be covered within the scope of protection of the present invention.
Claims
1. A high-antioxidant vegetable oil-based transformer insulating oil, characterized in that, The raw materials, by weight, include: 35-50 parts vegetable oil, 1-6 parts grafted titanium dioxide, 1-3 parts isocyanate, 5-15 parts liquid paraffin, 1-2 parts chitosan, 1-5 parts antioxidant, 1-2 parts emulsifier, 0.1-0.5 parts curing agent, 1-2 parts metal passivator, 1-2 parts diphenyl toluene phosphate, and 1-5 parts alkylphenol polyoxyethylene ether.
2. The high antioxidant vegetable oil-based transformer insulating oil according to claim 1, characterized in that, The vegetable oil is at least one of palm oil, rapeseed oil, and coconut oil.
3. The high antioxidant vegetable oil-based transformer insulating oil according to claim 1, characterized in that, Antioxidants include: 2,6-Di-tert-butyl-p-cresol, 2,6-Di-tert-butyl-4-methylphenol; The mass ratio of 2,6-di-tert-butyl-p-cresol to 2,6-di-tert-butyl-4-methylphenol is 1:0.1-0.
5.
4. The high antioxidant vegetable oil-based transformer insulating oil according to claim 1, characterized in that, The emulsifier is at least one of sorbitan monooleate, sorbitan monolaurate, sorbitan monopalmitate, sorbitan monostearate, and sorbitan tristearate.
5. The high antioxidant vegetable oil-based transformer insulating oil according to claim 1, characterized in that, The curing agent is amine 105 curing agent or triethylamine.
6. The high antioxidant vegetable oil-based transformer insulating oil according to claim 1, characterized in that, The metal passivating agent is benzotriazole or / and 5-methylbenzotriazole.
7. The high antioxidant vegetable oil-based transformer insulating oil according to claim 1, characterized in that, Grafted titanium dioxide is prepared by the following steps: nano-titanium dioxide particles and dodecyltrimethoxysilane are added to an ethanol aqueous solution and ultrasonically treated for 1-2 hours. Dendritic polyamide is added, the temperature is raised to 80-85℃, stirred for 10-20 minutes, ultrasonically treated for 1-2 hours, centrifuged, washed with ethanol, and vacuum dried.
8. The high antioxidant vegetable oil-based transformer insulating oil according to claim 7, characterized in that, The mass ratio of nano-titanium dioxide particles, dodecyltrimethoxysilane, and dendritic polyamide amine is 1-6:0.01-0.1:0.1-1.
9. The high antioxidant vegetable oil-based transformer insulating oil according to claim 7, characterized in that, After nano-titanium dioxide particles are added to an ethanol aqueous solution, the ultrasonic treatment frequency is 70-90kHz; after heating to 80-85℃, the ultrasonic treatment frequency is 70-80kHz.
10. A method for preparing a high-antioxidant vegetable oil-based transformer insulating oil as described in any one of claims 1-9, characterized in that, Includes the following steps: S1. Mix the antioxidant, isocyanate, and liquid paraffin evenly to obtain a pretreated antioxidant; Chitosan was added to an acetic acid solution and stirred until homogeneous. Then an emulsifier was added and stirred until homogeneous. A pretreated antioxidant was added dropwise while stirring at high speed. Stirring was continued for 20-50 minutes. A curing agent was added and stirred at 50-60°C for 10-20 hours. The mixture was cooled to room temperature, filtered, washed, and vacuum dried to obtain the microencapsulated antioxidant. S2. Vacuum filter the vegetable oil, add microencapsulated antioxidant and grafted titanium dioxide, stir at 50-70℃ for 10-30 min, add metal passivator, toluene diphenyl phosphate and alkylphenol polyoxyethylene ether and continue stirring for 5-15 min, sonicate for 10-20 min, and vacuum dry.