Biodegradable transformer oil based on microcapsule phase change material and preparation method thereof

Abstract

The invention discloses biodegradable transformer oil based on a microcapsule phase change material and a preparation method of the biodegradable transformer oil, the transformer oil is prepared from biodegradable base oil, the microcapsule phase change material, an antioxidant, an anti-wear agent and a metal deactivator according to the mass ratio of (70%-90%): (5%-20%): (0.5%-2%): (0.5%-2%): (0.1%-1%), the biodegradable base oil, the microcapsule phase change material, the antioxidant, the anti-wear agent and the metal deactivator are added into a reaction kettle, stirred for 1-3 h at the temperature of 50-80 DEG C and uniformly mixed, and then filtered to obtain the biodegradable transformer oil. The preparation method comprises the following steps: by taking melamine-formaldehyde resin as a wall material, dissolving a core material and a wall material monomer in deionized water, adding an emulsifier and a catalyst, carrying out in-situ polymerization reaction at 50-80 DEG C, and after the reaction is finished, filtering, washing and drying to obtain the microcapsule phase change material. The transformer oil disclosed by the invention has good biodegradability, high stability and excellent heat dissipation performance, and can effectively improve the operation reliability and prolong the service life of power equipment.

Description

Technical Field

[0001] The present invention belongs to the field of insulating materials for electrical equipment, and particularly relates to a biodegradable transformer oil based on microencapsulated phase change materials and a preparation method thereof. Background Art

[0002] Traditional transformer oil is a mineral oil refined from natural petroleum. After distillation and refining, it has the functions of insulation, heat dissipation, and arc extinction. It is mainly composed of hydrocarbons such as naphthenes, aromatics, and alkanes, and has good insulation and cooling properties, which can effectively protect the transformer and improve its operating efficiency. The insulation strength of traditional transformer oil is much higher than that of air, protecting the internal windings of the transformer from moisture and discharge erosion. It conducts the heat generated during the operation of the transformer to the radiator through oil circulation to maintain the stable temperature of the equipment. When the switch contacts are switched, the decomposed gas at high temperature enhances the arc extinction ability and quickly extinguishes the arc.

[0003] Traditional transformer oil depends on mineral oil and has problems such as flammability, poor biodegradability, and insufficient thermal stability. The existing improvement directions focus on synthetic esters or plant-based oils, but there are the following defects: The oxidation decomposition accelerates at high temperature, generating acidic substances that damage the equipment; The heat dissipation efficiency is passively dependent on convection and cannot actively buffer sudden temperature changes; It is difficult to balance the low-temperature fluidity and high-temperature stability.

[0004] Currently, there is no technical solution that combines phase change energy storage materials (PCM) with bio-based transformer oil.

[0005] Transformer oil is a key insulating and heat-dissipating medium in electrical equipment such as transformers, and its performance directly affects the operating stability and lifespan of electrical equipment. Traditional mineral insulating oil has problems such as poor biodegradability and large environmental pollution. With the increasing environmental protection requirements, the development of transformer oil with good biodegradability has become a research hotspot. At the same time, the transformer generates heat during operation, and the increase in oil temperature will affect its performance and lifespan. Therefore, it is necessary to develop a transformer oil with strong heat dissipation ability and high stability. Summary of the Invention

[0006] The purpose of the present invention is to provide a biodegradable transformer oil based on microencapsulated phase change materials and a preparation method thereof. This transformer oil has good biodegradability, high stability, and excellent heat dissipation performance, and can effectively improve the operating reliability and lifespan of electrical equipment.

[0007] To achieve the above purpose, the present invention adopts the following technical solutions: Biodegradable transformer oil based on microcapsule phase change materials, comprising: adding biodegradable base oil, microcapsule phase change materials, antioxidants, anti-wear agents and metal passivators into a reaction kettle according to a mass ratio of (70% - 90%):(5% - 20%):(0.5% - 2%):(0.5% - 2%):(0.1% - 1%), stirring at 50 - 80 °C for 1 - 3 h to mix evenly, and then obtaining the product through filtration.

[0008] A further improvement of the present invention lies in that: for the biodegradable base oil, a base oil with good biodegradability selected from vegetable oil-based or synthetic ester-based oils is used.

[0009] A further improvement of the present invention lies in that: for the microcapsule phase change materials, using modified fatty acids or paraffin as the core material and melamine-formaldehyde resin as the wall material, the microcapsule phase change materials are prepared by in-situ polymerization.

[0010] A further improvement of the present invention lies in that: for the antioxidants, hindered phenol antioxidants are selected.

[0011] A further improvement of the present invention lies in that: for the anti-wear agents, zinc dialkyldithiophosphate anti-wear agents are selected.

[0012] A further improvement of the present invention lies in that: for the metal passivators, benzotriazole metal passivators are selected.

[0013] The preparation method of the microcapsule phase change materials described above includes: Using melamine-formaldehyde resin as the wall material, dissolving the core material and the wall material monomers in deionized water, adding an emulsifier and a catalyst, and carrying out an in-situ polymerization reaction at 50 - 80 °C. After the reaction is completed, the microcapsule phase change materials are obtained through filtration, washing and drying.

[0014] A further improvement of the present invention lies in that the core material is modified fatty acids or paraffin.

[0015] A further improvement of the present invention lies in that the shell material of the high-temperature resistant polymer microcapsules is polymethyl methacrylate or silica composite.

[0016] A further improvement of the present invention lies in that the base oil is one or more of vegetable oil-based or synthetic ester-based oils with good biodegradation characteristics, such as palm oil, methyl oleate, isooctyl stearate or diisooctyl adipate.

[0017] Compared with the prior art, the present invention has at least the following beneficial technical effects: 1. The transformer oil of the present invention has excellent biodegradability, can achieve a high degradation rate in a short time, and significantly reduces environmental pollution. Compared with traditional mineral oils, biodegradable base oils can be decomposed by nature faster after leakage or disposal, reducing the long-term pollution risk to the environment such as soil and water bodies. The transformer oil of the present invention has excellent insulation performance, and its dielectric strength is much higher than that of air, which can form an effective insulation barrier between components at different potentials to ensure the safe operation of power equipment. At the same time, this transformer oil also has good heat dissipation performance and arc quenching performance, can effectively reduce the equipment temperature, extinguish the arc in time, and protect the power equipment from damage. The transformer oil of the present invention does not contain toxic substances such as aromatic ring compounds and is non-toxic or has extremely low toxicity to the environment. During production and use, it can significantly reduce carbon emissions and environmental pollution, meeting the current development trend of the energy green and low-carbon transformation. The transformer oil of the present invention also has excellent antioxidant susceptibility, extreme pressure and anti-wear properties, oxidation stability, thermal stability, and viscosity-temperature characteristics, etc. This transformer oil has good compatibility with mineral oils and ester oils and can be miscible with them in any proportion, which is convenient for practical applications. In addition, this transformer oil also has excellent corrosion resistance, which can protect the metal components inside the power equipment from oxidation and corrosion.

[0018] 2. The addition of microencapsulated phase change materials endows transformer oil with excellent heat dissipation performance, which can effectively reduce the oil temperature, improve the operation stability and lifespan of power equipment. The microencapsulated phase change materials absorb and release latent heat through solid-liquid phase change. When the transformer oil temperature rises to the phase change temperature, the core material melts from solid to liquid, absorbing a large amount of heat and effectively reducing the oil temperature. On the contrary, when the oil temperature drops, the core material solidifies and releases heat to maintain the oil temperature stability and avoid performance degradation caused by too low oil temperature. The addition of microencapsulated phase change materials significantly improves the heat dissipation efficiency of transformer oil, enabling the transformer to reach thermal equilibrium faster when the load changes and reducing heat accumulation. The measured data shows that the hot spot temperature of transformer oil added with microencapsulated phase change materials can be reduced by more than 20% under full load, and the temperature rise rate slows down by nearly 50%. The microencapsulated phase change materials regulate the heat flow distribution through local phase change, reduce the temperature difference between different components inside the transformer, lower the thermal stress, and improve the operation stability of the equipment. Temperature homogenization also helps to reduce mechanical stress caused by uneven thermal expansion and extend the equipment lifespan. The reduction of the oil temperature directly slows down the oxidation reaction rate of transformer oil and delays the oil quality deterioration process. The antioxidant core material in the microencapsulated phase change materials can further inhibit the oxidation reaction and protect the transformer oil from aging. The reduction of the transformer oil temperature reduces the energy loss caused by heat conduction and convection, improving the energy utilization efficiency of the transformer. During long-term operation, this advantage can significantly reduce the energy consumption and operation cost of the transformer. Since the addition of microencapsulated phase change materials delays the aging process of transformer oil, the oil change cycle and maintenance cycle of the transformer can be extended, reducing the maintenance cost. The addition of microencapsulated phase change materials helps to reduce the leakage risk of transformer oil because the phase change materials can absorb part of the leaked oil, reducing the impact on the environment. At the same time, the slowdown of the aging of transformer oil also reduces the generation and treatment cost of waste oil.

[0019] 3. By adding antioxidants, anti-wear agents and metal deactivators, the antioxidant performance, anti-wear performance and stability of transformer oil are improved, ensuring the performance stability of transformer oil during long-term use. Among them, the antioxidant interrupts the free radical chain oxidation reaction of hydrocarbon molecules in transformer oil by providing hydrogen atoms, delaying the oil quality deterioration. The anti-wear agent decomposes under high temperature and high pressure to form a sulfide or phosphate protective film on the metal surface, reducing friction and wear. The metal deactivator forms chelates with metal ions such as copper and iron, inhibiting their catalytic oxidation reaction. The metal deactivator reduces the decomposition of antioxidants by metal ions and extends their effective action time. The antioxidant delays the oil oxidation, maintains the activity of the decomposition products of the anti-wear agent, and enhances the durability of the protective film.

[0020] In summary, the biodegradable transformer oil based on microencapsulated phase change materials and its preparation method provided by the present invention have good biodegradability, high stability and excellent heat dissipation performance, and can effectively improve the operation reliability and lifespan of power equipment. Brief Description of the Drawings

[0021] In order to more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following will briefly introduce the drawings required for the description of the specific embodiments or the prior art. Obviously, the drawings in the following description are some embodiments of the present invention. For those of ordinary skill in the art, without creative efforts, other drawings can also be obtained based on these drawings.

[0022] Figure 1 SEM of the prepared microcapsule phase change material. Specific Embodiments

[0023] In the following text, only some exemplary embodiments are simply described. As those skilled in the art can recognize, the described embodiments can be modified in various different ways without departing from the spirit or scope of the present invention. Therefore, the drawings and the description are considered to be exemplary in nature rather than restrictive.

[0024] In the description of the present invention, it should be understood that when used in this specification and the appended claims, the terms "comprising" and "including" indicate the presence of the described features, wholes, steps, operations, elements, and / or components, but do not exclude the presence or addition of one or more other features, wholes, steps, operations, elements, components, and / or their combinations.

[0025] It should also be understood that the terms used in the specification of the present invention are only for the purpose of describing specific embodiments and are not intended to limit the present invention. As used in the specification of the present invention and the appended claims, unless the context clearly indicates otherwise, the singular forms "a", "an", and "the" are intended to include the plural forms.

[0026] It should be further understood that the term " / and" used in the specification of the present invention and the appended claims refers to any combination and all possible combinations of one or more of the associated listed items, and includes these combinations.

[0027] Various structural schematic diagrams according to the disclosed embodiments of the present invention are shown in the drawings. These figures are not drawn to scale, where for the purpose of clear expression, some details are enlarged and some details may be omitted. The shapes of various regions and layers shown in the figures and their relative sizes and positional relationships are only exemplary. In practice, there may be deviations due to manufacturing tolerances or technical limitations, and those skilled in the art can design regions / layers with different shapes, sizes, and relative positions according to actual needs.

[0028] The following will describe the embodiments of the present invention in detail with reference to the drawings.

[0029] The biodegradable transformer oil based on microcapsule phase change materials provided by the present invention includes: 1. Composition of the transformer oil: The transformer oil of the present invention is mainly composed of a biodegradable base oil, microcapsule phase change materials, antioxidants, antiwear agents, and metal deactivators in a set ratio. The mass ratio of the biodegradable base oil, microcapsule phase change materials, antioxidants, antiwear agents, and metal deactivators is: (70% - 90%):(5% - 20%):(0.5% - 5%):(0.5% - 3%):(0.1% - 2%).

[0030] Biodegradable base oil: A base oil with good biodegradability such as vegetable oil-based or synthetic ester-based is selected, and its content is 70 - 90 wt%. The base oil is one or more of palm oil, methyl oleate, isooctyl stearate, or diisooctyl adipate, which are vegetable oil-based or synthetic ester-based with good biodegradation characteristics.

[0031] Microcapsule phase change materials: Using paraffin wax, etc. as the core material and melamine-formaldehyde resin, etc. as the wall material, microcapsule phase change materials are prepared by in-situ polymerization. Its content is 5 - 20 wt%. The microcapsule phase change materials can absorb heat and undergo a phase change when the temperature of the transformer oil rises, thereby effectively reducing the oil temperature and improving the heat dissipation performance.

[0032] Antioxidants: Hindered phenol antioxidants such as 2,6-di-tert-butyl-p-cresol are selected, and the content is 0.5 - 5 wt%. It can effectively inhibit the oxidation of the transformer oil and improve its stability.

[0033] Antiwear agents: Antiwear agents such as zinc dialkyldithiophosphate are selected, and the content is 0.5 - 3 wt%. It can improve the antiwear performance of the transformer oil and reduce equipment wear.

[0034] Metal deactivators: Metal deactivators such as benzotriazole are selected, and the content is 0.1 - 2 wt%. It can prevent the influence of metal impurities on the performance of the transformer oil.

[0035] 2. Preparation of microcapsule phase change materials: Dissolve the core material and wall material monomers in a suitable solvent, add an emulsifier and a catalyst, and carry out an in-situ polymerization reaction at a set temperature. After the reaction is completed, the microcapsule phase change materials are obtained through steps such as filtration, washing, and drying. Since the microcapsules will undergo a solid-liquid phase change and absorb heat at 40 - 80 °C, it has the effects of reducing the peak temperature of the transformer oil and reducing equipment thermal stress.

[0036] 3. Preparation of the transformer oil: Add the biodegradable base oil, microcapsule phase change materials, antioxidants, antiwear agents, and metal deactivators to the reaction kettle in proportion, stir at 50 - 80 °C for 1 - 3 h to mix evenly, and then obtain the finished transformer oil through filtration.

[0037] The preparation method of the microcapsule phase change material provided by the present invention includes: Using melamine-formaldehyde resin as the wall material, dissolving the core material and the wall material monomers in deionized water, adding an emulsifier and a catalyst, and carrying out an in-situ polymerization reaction at 50-80°C. After the reaction is completed, the microcapsule phase change material is obtained through filtration, washing, and drying.

[0038] The core material is a modified fatty acid or paraffin.

[0039] The shell material of the high-temperature resistant polymer microcapsule is polymethyl methacrylate or a silica composite.

[0040] Among them, polymethyl methacrylate is an amorphous transparent thermoplastic polymer with high transparency, and its light transmittance can reach 92%, even higher than that of glass. The low water absorption of polymethyl methacrylate enables it to maintain stable performance in various environments. Polymethyl methacrylate has a wide range of applications in the biological field. The mechanical strength of polymethyl methacrylate is relatively high, and its ability to resist stretching and impact is 7-18 times higher than that of ordinary glass. The heat distortion temperature of polymethyl methacrylate is about 80°C. Although its heat resistance is not as good as some high-temperature materials, it is sufficient for many applications. Polymethyl methacrylate can be used as the shell material of microcapsules to encapsulate various active ingredients, such as thermochromic materials, phase change materials, etc., to achieve specific functions.

[0041] Silica has an extremely high specific surface area, which endows it with strong adsorption properties and reaction activity. Silica has high thermal stability and can maintain stable performance in high-temperature environments. Silica is non-toxic to cells and has good biocompatibility, making it suitable for the biomedical field. Silica can be compounded with a variety of polymers to form composite materials with specific properties. The silica composite can be used as the shell material of microcapsules, providing excellent thermal stability and mechanical properties, and is suitable for application scenarios that require high-temperature stability.

[0042] The base oil is one or more of palm oil, methyl oleate, isooctyl stearate, or diisooctyl adipate, which are vegetable oil-based or synthetic ester-based with good biodegradation characteristics.

[0043] Among them, palm oil is obtained through transesterification reaction and belongs to renewable resources. Monounsaturated fatty acid esters have better oxidation stability than polyunsaturated fatty acid esters. Diisooctyl adipate has a double ester structure, with a long molecular chain and branching, which improves the thermal stability. The pour point of isooctyl stearate is -30°C, making it highly applicable in extremely cold regions.

[0044] Example 1: As Figure 1As shown in the figure, preparation of microcapsule phase change material: Dissolve 10 g of paraffin in 50 mL of cyclohexane as the core material phase, dissolve 5 g of melamine and 3 g of formaldehyde in 30 mL of deionized water, add appropriate amounts of emulsifier and catalyst, and stir and emulsify at 50 °C to form an oil-in-water emulsion. Then slowly drip the core material phase into the oil-in-water emulsion, react at 60 °C for 3 h, and after the reaction, obtain the microcapsule phase change material through filtration, washing, and drying.

[0045] Preparation of transformer oil: Add 90 g of vegetable oil-based base oil, 5 g of the microcapsule phase change material prepared above, 2 g of 2,6-di-tert-butyl-p-cresol, 2 g of zinc dialkyldithiophosphate, and 1 g of benzotriazole into a reaction kettle, stir and mix evenly at 50 °C, and obtain transformer oil through filtration.

[0046] Example 2: As Figure 1 shown in the figure, preparation of microcapsule phase change material: Using a method similar to that of Example 1, replace the core material with 12 g of paraffin and the wall material with 6 g of melamine and 4 g of formaldehyde to prepare the microcapsule phase change material.

[0047] Preparation of transformer oil: Add 90 g of synthetic ester-based base oil, 8.9 g of the microcapsule phase change material prepared above, 0.5 g of 2,6-di-tert-butyl-p-cresol, 0.5 g of zinc dialkyldithiophosphate, and 0.1 g of benzotriazole into a reaction kettle, stir and mix evenly at 80 °C, and obtain transformer oil through filtration.

[0048] Example 3: Preparation of microcapsule phase change material: Dissolve 10 g of paraffin in 50 mL of cyclohexane as the core material phase, dissolve 5 g of melamine and 3 g of formaldehyde in 30 mL of deionized water, add appropriate amounts of emulsifier and catalyst, and stir and emulsify at 50 °C to form an oil-in-water emulsion. Then slowly drip the core material phase into the oil-in-water emulsion, react at 60 °C for 3 h, and after the reaction, obtain the microcapsule phase change material through filtration, washing, and drying.

[0049] Preparation of transformer oil: Add 85 g of synthetic ester-based base oil, 12 g of the microcapsule phase change material prepared above, 1 g of 2,6-di-tert-butyl-p-cresol, 1.5 g of zinc dialkyldithiophosphate, and 0.5 g of benzotriazole into a reaction kettle, stir and mix evenly at 65 °C, and obtain transformer oil through filtration.

[0050] Example 4: Preparation of microcapsule phase change material: Using a method similar to that of Example 1, replace the core material with 12 g of paraffin and the wall material with 6 g of melamine and 4 g of formaldehyde to prepare the microcapsule phase change material.

[0051] Preparation of transformer oil: Add 70 g of synthetic ester-based base oil, 20 g of the microcapsule phase change material prepared above, 5 g of 2,6-di-tert-butyl-p-cresol, 3 g of zinc dialkyldithiophosphate, and 2 g of benzotriazole into a reaction kettle, stir and mix evenly at 65 °C, and obtain transformer oil through filtration.

[0052] In summary, in view of the problems of poor biodegradability, high environmental pollution risk, and insufficient heat dissipation efficiency of traditional mineral-based transformer oil, the present invention innovatively develops a biodegradable transformer oil based on microcapsule phase change materials. By combining modified fatty acid / paraffin phase change microcapsules with bio-based base oils (such as palm oil methyl ester and diisooctyl adipate), the transformer oil realizes the synergistic improvement of biodegradability, high stability, and excellent heat dissipation performance, and can significantly improve the operation reliability and service life of power equipment (such as transformers and switchgear).

[0053] The foregoing shows and describes the basic principles, main features, and advantages of the present invention. For those skilled in the art, it is obvious that the present invention is not limited to the details of the above-described exemplary embodiments, and without departing from the spirit or basic characteristics of the present invention, the present invention can be implemented in other specific forms. Therefore, in any regard, the embodiments should be regarded as exemplary and non-limiting. The scope of the present invention is defined by the appended claims rather than the above description. Therefore, all changes falling within the meaning and scope of the equivalent elements of the claims are intended to be encompassed within the present invention. Any reference signs in the claims should not be construed as limiting the claimed rights.

[0054] In addition, it should be understood that although this specification is described in terms of embodiments, not every embodiment only contains an independent technical solution. This narrative manner of the specification is only for clarity. Those skilled in the art should regard the specification as a whole, and the technical solutions in each embodiment can also be appropriately combined to form other embodiments that can be understood by those skilled in the art. The above content is only to illustrate the technical idea of the present invention, and the protection scope of the present invention cannot be limited thereby. Any modification made on the basis of the technical solution according to the technical idea proposed by the present invention falls within the protection scope of the claims of the present invention.

Claims

1. A biodegradable transformer oil based on microcapsule phase change materials, characterized in that, Comprising: According to a mass ratio of (70% - 90%):(5% - 20%):(0.5% - 2%):(0.5% - 2%):(0.1% - 1%), a biodegradable base oil, a microcapsule phase change material, an antioxidant, an antiwear agent, and a metal deactivator are added into a reaction kettle, stirred at 50 - 80 °C for 1 - 3 h until evenly mixed, and then obtained through filtration.

2. The biodegradable transformer oil based on microcapsule phase change material according to claim 1, wherein Biodegradable base oil: A base oil with good biodegradability selected from vegetable oil - based or synthetic ester - based oils.

3. The biodegradable transformer oil based on microcapsule phase change material according to claim 1, wherein Microcapsule phase change material: Using modified fatty acid or paraffin as the core material and melamine - formaldehyde resin as the wall material, the microcapsule phase change material is prepared by in - situ polymerization.

4. The biodegradable transformer oil based on microcapsule phase change material according to claim 1, characterized in that, Antioxidant: A hindered phenol - type antioxidant is selected.

5. The biodegradable transformer oil based on microcapsule phase change material according to claim 1, wherein Antiwear agent: A zinc dialkyldithiophosphate antiwear agent is selected.

6. A biodegradable transformer oil based on microcapsule phase change material according to claim 1, characterized in that, Metal deactivator: A benzotriazole metal deactivator is selected.

7. The preparation method of the microcapsule phase change material according to claim 1, characterized in that, Comprising: Using melamine - formaldehyde resin as the wall material, the core material and the wall material monomers are dissolved in deionized water, an emulsifier and a catalyst are added, and an in - situ polymerization reaction is carried out at 50 - 80 °C. After the reaction ends, the microcapsule phase change material is obtained through filtration, washing, and drying.

8. The preparation method of the microcapsule phase change material according to claim 7, characterized in that, The core material is modified fatty acid or paraffin.

9. The preparation method of the microcapsule phase change material according to claim 7, characterized in that, The shell material of the high - temperature - resistant polymer microcapsule is polymethyl methacrylate or a silica complex.

10. The preparation method of the microcapsule phase change material according to claim 7, wherein, The base oil is one or more of palm oil, methyl oleate, isooctyl stearate, or diisooctyl adipate, which are vegetable oil - based or synthetic ester - based oils with good biodegradation characteristics.

Images