Composite impregnant for metallized film capacitor and preparation method of composite impregnant

Abstract

The invention discloses a composite impregnant for a metallized film capacitor and a preparation method of the composite impregnant. The composite impregnant comprises the following components in parts by weight: 50-70 parts of trimethylolpropane ester; 10 to 30 parts of nettle oil; 10 to 20 parts of epoxidized soybean oil; 0.1 to 1 part of an antioxidant; 0.01 to 0.1 part of a metal deactivator; 0.05 to 0.5 part of polycarbodiimide; the trimethylolpropane ester, the nettle oil and the epoxidized soybean oil serve as main raw materials, the antioxidant, the metal deactivator, the polycarbodiimide and the nanometer aluminum oxide serve as auxiliary additives, the materials are environmentally friendly, chemical reaction is stable in the preparation method process, operation is easy, and good economic benefits and environmental protection benefits are achieved.

Description

Technical Field

[0001] The invention belongs to the field of capacitors, and in particular relates to a composite impregnating agent for metallized film capacitors and a preparation method thereof. Background Art

[0002] Metallized film capacitor impregnants are mainly used to fill the inside of capacitors and improve the performance of capacitors. Their functions include improving the withstand voltage performance of capacitors, reducing losses, improving heat dissipation, and many other aspects. Currently, the most commonly used is a mixture of synthetic oil and vegetable oil. Synthetic oils mainly include alkylbenzene, phenylxylene ethane, mono / dibenzyltoluene, poly-α-olefin, silicone oil, etc. Vegetable oils mainly include safflower oil, peanut oil, linseed oil, sunflower oil, etc. Due to the limitation of base mineral oil in synthetic oil, the performance is relatively ordinary and not friendly to the environment. Vegetable oil has the disadvantages of poor chemical stability and limited thermal stability. Now there is a lack of a green and environmentally friendly impregnant with stable chemical properties and good electrical properties. Summary of the invention

[0003] In view of the problems of the prior art, the present invention provides a composite impregnating agent for metallized film capacitors and a preparation method thereof. The specific technical scheme is as follows:

[0004] The present invention provides a composite impregnating agent for a metallized film capacitor, which comprises the following components by weight:

[0005] Trimethylolpropane ester 50-70 parts

[0006] 10-30 parts nettle oil

[0007] Epoxidized soybean oil 10-20 parts

[0008] Antioxidant 0.1-1 part

[0009] Metal passivator 0.01-0.1 parts

[0010] Polycarbodiimide 0.05-0.5 parts

[0011] Nano alumina 0.1-1 part.

[0012] As an improvement of the above technical solution, the above antioxidant is one or more of 2,6-di-tert-butyl-4-methylphenol, dilauryl thiodipropionate and propyl gallate, preferably 2,6-di-tert-butyl-4-methylphenol.

[0013] As an improvement of the above technical solution, the above metal passivator is benzotriazole.

[0014] In the above technical scheme: trimethylolpropane ester has moderate viscosity and good electrical insulation performance, and its relatively high dielectric constant helps to increase the capacitance value of the capacitor, and can effectively impregnate various parts of the capacitor to form a stable insulating layer; nettle oil also has insulating properties, can assist in adjusting the dielectric properties of the impregnant, and contains antioxidant ingredients, which can improve the antioxidant capacity of the impregnant. Its lubricity also helps to improve the fluidity of the impregnant, so that the impregnant can better fill the gaps inside the capacitor; epoxidized soybean oil acts as a plasticizer, increases the flexibility of the impregnant, and enables the impregnant to better adapt to the physical changes of the capacitor in different working environments. At the same time, it also has certain antioxidant properties, and synergizes with its antioxidant to enhance the chemical stability of the impregnant; the metal passivator can be used in the metal of the capacitor. A protective film is formed on the electrode surface to prevent the metal from reacting with the active ingredients or impurities in the impregnant, avoiding corrosion and oxidation of the metal electrode, thereby improving the stability and service life of the capacitor; polycarbodiimide, as an anti-hydrolysis agent, can react with moisture or acidic or alkaline substances that may cause hydrolysis, slow down the hydrolysis process of the impregnant, and maintain the chemical stability of the impregnant, especially playing an important role in humid environments or when the capacitor is poorly sealed; nano-alumina can improve the dielectric properties and heat dissipation properties of the impregnant. Its high specific surface area and special physical and chemical properties can enhance the uniformity of the electric field distribution of the impregnant, reduce local electric field concentration, and improve the withstand voltage of the capacitor. At the same time, nano-alumina can increase the thermal conductivity of the impregnant, which is beneficial to the heat dissipation of the capacitor during operation, reduce the internal temperature, and improve the stability of the capacitor.

[0015] On the other hand, the present invention provides a method for preparing the composite impregnant of the metallized film capacitor, comprising the following steps:

[0016] S1, prepare raw materials according to the required weight parts;

[0017] S2, add trimethylolpropane ester and nettle oil into the reaction kettle, slowly heat to 40-60°C, and stir at the same time, the stirring speed is 300-500r / min, and the stirring time is 1-2h;

[0018] S3, adding an antioxidant to the mixed solution treated in step S2, and stirring continuously for 0.5-1h;

[0019] S4, adding the epoxidized soybean oil to the mixed solution treated in step S3, increasing the stirring speed to 500-800 r / min, and continuing stirring for 2-3 h;

[0020] S5. Dissolve the metal passivator and polycarbodiimide in ethanol, add into the reaction kettle, and continue stirring for 0.5-1h;

[0021] S6. Add nano-alumina to the reactor, reduce the stirring speed to 200-300 r / min, and continue stirring for 0.5-1 h;

[0022] S7, degassing the mixed solution after step S6 under vacuum conditions for 1-2 hours;

[0023] S8. Filter the degassed mixed solution to obtain an impregnating agent.

[0024] As an improvement of the above technical solution, after adding nano-alumina in the above step S6, the reactor is placed in an ultrasonic environment with an ultrasonic frequency of 60-80kHz and an ultrasonic power of 100-200W.

[0025] As an improvement of the above technical solution, a 0.2-0.3 μm filter membrane is used for filtration in the above step S8.

[0026] In the above technical scheme: step S2 ensures that trimethylolpropane ester and castor oil are evenly mixed; step S3 adds an antioxidant and stirs to make the antioxidant molecules evenly dispersed in the previous mixed solution, effectively captures the free radicals generated in the entire impregnating agent system, prevents the impregnating agent from oxidation during long-term use, and extends the service life of the impregnating agent; step S4 adds epoxidized soybean oil again and stirs to ensure that the epoxidized soybean oil is fully integrated into the system. The epoxidized soybean oil is used as a plasticizer. Its full mixing can fully improve the flexibility of the impregnating agent, and can work synergistically with the antioxidant. It also helps to adjust the fluidity of the impregnating agent to make it more suitable. Impregnating the capacitor; Step S5: dissolving the metal passivator and polycarbodiimide in ethanol and then adding them, so that they can be better dispersed in the mixed system of the reactor in a molecular or ionic state, play their role in protecting the metal electrode and preventing hydrolysis, and improve the stability of the impregnant and the capacitor; Step S6: adding nano-alumina and ultrasonically stirring, so that the nano-alumina can be dispersed in the impregnant as evenly as possible, play its role in improving the dielectric properties and heat dissipation properties, avoid local performance abnormalities due to agglomeration, and ensure the high performance of the capacitor impregnant; Steps S7 and S8 mainly remove the gas, volatile impurities and solid impurities in the impregnant to ensure the purity of the impregnant.

[0027] In summary, the beneficial effects of the present invention are:

[0028] (1) The present invention provides a composite impregnating agent for metallized film capacitors, which uses trimethylolpropane ester, nettle oil and epoxidized soybean oil as main raw materials, has good chemical stability and thermal stability, is environmentally friendly, and has good economic and environmental benefits.

[0029] (2) The present invention provides a method for preparing a composite impregnating agent for metallized film capacitors. The method has stable chemical reaction and simple operation, and is suitable for popularization and use. DETAILED DESCRIPTION

[0030] In order to make the purpose, technical solution and advantages of the embodiments of the present invention more clear, the technical solution of the present invention will be clearly and completely described below in conjunction with the embodiments.

[0031] The chemical and biological raw materials used in the present invention can all be purchased from the market and will not have a significant impact on the results.

[0032] Embodiment 1

[0033] A composite impregnating agent for metallized film capacitors comprises the following components by weight: 500 g of trimethylolpropane ester, 300 g of nettle oil, 200 g of epoxidized soybean oil, 5 g of 2,6-di-tert-butyl-4-methylphenol, 0.5 g of benzotriazole, 2 g of polycarbodiimide and 5 g of nano-alumina.

[0034] The preparation method comprises the following steps:

[0035] S1, prepare raw materials according to the above parts by weight;

[0036] S2, adding trimethylolpropane ester and nettle oil into the reaction kettle, slowly heating to 50°C, stirring at the same time, the stirring speed is 400r / min, and the stirring time is 1.5h;

[0037] S3, adding an antioxidant to the mixed solution treated in step S2, and stirring continuously for 0.5 h;

[0038] S4, adding epoxidized soybean oil to the mixed solution treated in step S3, increasing the stirring speed to 600 r / min, and continuing stirring for 2 h;

[0039] S5, dissolving the metal passivator and polycarbodiimide in ethanol, adding them into the reaction kettle, and continuing stirring for 1 hour;

[0040] S6. Add nano-alumina to the reactor, place the reactor in an ultrasonic environment, set the ultrasonic frequency to 60kHz, and the ultrasonic power to 150W. Reduce the stirring speed to 300r / min and continue stirring for 1h.

[0041] S7, degassing the mixed solution after step S6 under vacuum conditions for 1 hour;

[0042] S8. Filter the degassed mixed solution using a 0.2 μm filter membrane to obtain an impregnating agent.

[0043] Embodiment 2

[0044] A composite impregnating agent for metallized film capacitors comprises the following components by weight: 700 g of trimethylolpropane ester, 100 g of nettle oil, 100 g of epoxidized soybean oil, 5 g of 2,6-di-tert-butyl-4-methylphenol, 0.5 g of benzotriazole, 2 g of polycarbodiimide and 5 g of nano-alumina.

[0045] The preparation method comprises the following steps:

[0046] S1, prepare raw materials according to the above parts by weight;

[0047] S2, adding trimethylolpropane ester and nettle oil into the reaction kettle, slowly heating to 50°C, stirring at the same time, the stirring speed is 400r / min, and the stirring time is 1.5h;

[0048] S3, adding an antioxidant to the mixed solution treated in step S2, and stirring continuously for 0.5 h;

[0049] S4, adding epoxidized soybean oil to the mixed solution treated in step S3, increasing the stirring speed to 600 r / min, and continuing stirring for 2 h;

[0050] S5, dissolving the metal passivator and polycarbodiimide in ethanol, adding them into the reaction kettle, and continuing stirring for 1 hour;

[0051] S6. Add nano-alumina to the reactor, place the reactor in an ultrasonic environment, set the ultrasonic frequency to 60kHz, and the ultrasonic power to 150W. Reduce the stirring speed to 300r / min and continue stirring for 1h.

[0052] S7, degassing the mixed solution after step S6 under vacuum conditions for 1 hour;

[0053] S8. Filter the degassed mixed solution using a 0.2 μm filter membrane to obtain an impregnating agent.

[0054] Embodiment 3

[0055] A composite impregnating agent for metallized film capacitors comprises the following components by weight: 600 g of trimethylolpropane ester, 200 g of nettle oil, 150 g of epoxidized soybean oil, 5 g of 2,6-di-tert-butyl-4-methylphenol, 0.5 g of benzotriazole, 2 g of polycarbodiimide and 5 g of nano-alumina.

[0056] The preparation method comprises the following steps:

[0057] S1, prepare raw materials according to the above parts by weight;

[0058] S2, adding trimethylolpropane ester and nettle oil into the reaction kettle, slowly heating to 50°C, stirring at the same time, the stirring speed is 400r / min, and the stirring time is 1.5h;

[0059] S3, adding an antioxidant to the mixed solution treated in step S2, and stirring continuously for 0.5 h;

[0060] S4, adding epoxidized soybean oil to the mixed solution treated in step S3, increasing the stirring speed to 600 r / min, and continuing stirring for 2 h;

[0061] S5, dissolving the metal passivator and polycarbodiimide in ethanol, adding them into the reaction kettle, and continuing stirring for 1 hour;

[0062] S6. Add nano-alumina to the reactor, place the reactor in an ultrasonic environment, set the ultrasonic frequency to 60kHz, and the ultrasonic power to 150W. Reduce the stirring speed to 300r / min and continue stirring for 1h.

[0063] S7, degassing the mixed solution after step S6 under vacuum conditions for 1 hour;

[0064] S8. Filter the degassed mixed solution using a 0.2 μm filter membrane to obtain an impregnating agent.

[0065] Comparative Example 1

[0066] A composite impregnating agent for metallized film capacitors comprises the following components by weight: 400 g of trimethylolpropane ester, 400 g of nettle oil, 300 g of epoxidized soybean oil, 5 g of 2,6-di-tert-butyl-4-methylphenol, 0.5 g of benzotriazole, 2 g of polycarbodiimide and 5 g of nano-alumina.

[0067] The preparation method comprises the following steps:

[0068] S1, prepare the raw materials according to the above-mentioned parts by weight;

[0069] S2, adding trimethylolpropane ester and nettle oil into the reaction kettle, slowly heating to 50°C, stirring at the same time, the stirring speed is 400r / min, and the stirring time is 1.5h;

[0070] S3, adding an antioxidant to the mixed solution treated in step S2, and stirring continuously for 0.5 h;

[0071] S4, adding epoxidized soybean oil to the mixed solution treated in step S3, increasing the stirring speed to 600 r / min, and continuing stirring for 2 h;

[0072] S5, dissolving the metal passivator and polycarbodiimide in ethanol, adding them into the reaction kettle, and continuing stirring for 1 hour;

[0073] S6. Add nano-alumina to the reactor, place the reactor in an ultrasonic environment, set the ultrasonic frequency to 60kHz, and the ultrasonic power to 150W. Reduce the stirring speed to 300r / min and continue stirring for 1h.

[0074] S7, degassing the mixed solution after step S6 under vacuum conditions for 1 hour;

[0075] S8. Filter the degassed mixed solution using a 0.2 μm filter membrane to obtain an impregnating agent.

[0076] Comparative Example 2

[0077] A composite impregnating agent for metallized film capacitors comprises the following components by weight: 800 g of trimethylolpropane ester, 50 g of nettle oil, 50 g of epoxidized soybean oil, 5 g of 2,6-di-tert-butyl-4-methylphenol, 0.5 g of benzotriazole, 2 g of polycarbodiimide and 5 g of nano-alumina.

[0078] The preparation method comprises the following steps:

[0079] S1, prepare the raw materials according to the above-mentioned parts by weight;

[0080] S2, adding trimethylolpropane ester and nettle oil into the reaction kettle, slowly heating to 50°C, stirring at the same time, the stirring speed is 400r / min, and the stirring time is 1.5h;

[0081] S3, adding an antioxidant to the mixed solution treated in step S2, and stirring continuously for 0.5 h;

[0082] S4, adding epoxidized soybean oil to the mixed solution treated in step S3, increasing the stirring speed to 600 r / min, and continuing stirring for 2 h;

[0083] S5, dissolving the metal passivator and polycarbodiimide in ethanol, adding them into the reaction kettle, and continuing stirring for 1 hour;

[0084] S6. Add nano-alumina to the reactor, place the reactor in an ultrasonic environment, set the ultrasonic frequency to 60kHz, and the ultrasonic power to 150W. Reduce the stirring speed to 300r / min and continue stirring for 1h.

[0085] S7, degassing the mixed solution after step S6 under vacuum conditions for 1 hour;

[0086] S8. Filter the degassed mixed solution using a 0.2 μm filter membrane to obtain an impregnating agent.

[0087] A batch of capacitors with intact shells and metallized films were selected, and the capacitor electrode lead wires were cleaned and divided into five groups. They were vacuum impregnated in the impregnants of the embodiments and comparative examples provided by the present invention, and after impregnation, they were first air-dried and then baked to ensure that the impregnant was dry and fully combined with the metallized film and other components of the capacitor, and the quality of the impregnant itself and the treated capacitors was inspected.

[0088] The electrical performance testing standards refer to GB / T 2693-2001, IEC 60384-1:2016, etc.

[0089] Environmental adaptability testing standards refer to GB / T2423.2, IEC60068-2-2, etc.

[0090] The self-healing test standard refers to GB / T 17702-2021.

[0091] The test results are shown in Table 1.

[0092]

[0093] Table 1

[0094] As can be seen from Table 1, the impregnant prepared by the present invention has good electrical properties, environmental adaptability and self-healing properties, mainly because trimethylolpropane ester has a low freezing point, and the addition of antioxidants and epoxidized soybean oil jointly enhances the antioxidant property of the impregnant. The dielectric loss tangent values ​​of trimethylolpropane ester and the main materials, nettle oil and epoxidized soybean oil, are all low. Among them, epoxidized soybean oil reduces the viscosity of the impregnant, making it have better fluidity. The addition of nano-alumina improves the self-healing property of the impregnant, making it more suitable for metallized film capacitors.

[0095] The above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A composite impregnating agent for metallized film capacitors, characterized in that: The following components are included by weight: Trimethylolpropane ester 50-70 parts 10-30 parts nettle oil Epoxidized soybean oil 10-20 parts Antioxidant 0.1-1 part Metal passivator 0.01-0.1 parts Polycarbodiimide 0.05-0.5 parts Nano alumina 0.1-1 part.

2. The composite impregnating agent for metallized film capacitors according to claim 1, characterized in that: The antioxidant is one or more of 2,6-di-tert-butyl-4-methylphenol, dilauryl thiodipropionate and propyl gallate, preferably 2,6-di-tert-butyl-4-methylphenol.

3. The composite impregnating agent for metallized film capacitors according to claim 1, characterized in that: The metal passivator is benzotriazole.

4. A method for preparing a composite impregnant for a metallized film capacitor according to any one of claims 1 to 3, characterized in that: The following steps are involved: S1. Prepare raw materials by weight; S2, add trimethylolpropane ester and nettle oil into the reaction kettle, slowly heat to 40-60°C, and stir at the same time, the stirring speed is 300-500r / min, and the stirring time is 1-2h; S3, adding an antioxidant to the mixed solution treated in step S2, and stirring continuously for 0.5-1h; S4, adding the epoxidized soybean oil to the mixed solution treated in step S3, increasing the stirring speed to 500-800 r / min, and continuing stirring for 2-3 h; S5. Dissolve the metal passivator and polycarbodiimide in ethanol, add into the reaction kettle, and continue stirring for 0.5-1h; S6. Add nano-alumina to the reactor, reduce the stirring speed to 200-300 r / min, and continue stirring for 0.5-1 h; S7, degassing the mixed solution after step S6 under vacuum conditions for 1-2 hours; S8. Filter the degassed mixed solution to obtain an impregnating agent.

5. The method for preparing the composite impregnating agent for metallized film capacitors according to claim 4, characterized in that: After adding the nano-alumina in step S6, the reactor is placed in an ultrasonic environment with an ultrasonic frequency of 60-80 kHz and an ultrasonic power of 100-200 W.

6. The method for preparing the composite impregnating agent for double metallized film capacitors according to claim 4, characterized in that: In the step S8, a 0.2-0.3 μm filter membrane is used for filtration.

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