Modified copper oxide nanosieve, synthetic ester insulating oil and preparation method thereof

Abstract

The application discloses modified copper oxide nanosieve, synthetic ester insulating oil and a preparation method thereof, and relates to the field of insulating oil. The synthetic ester insulating oil comprises 0.1wt%-0.4wt% modified copper oxide nanosieve. The preparation method of the modified copper oxide nanosieve comprises the following steps: (1) preparing copper oxide nanosieve by adopting a sol-gel method; (2) coating a silane coupling agent on the surface of the copper oxide nanosieve to activate the copper oxide nanosieve; and (3) heating and reacting the activated copper oxide nanosieve and linoleic acid to obtain the modified copper oxide nanosieve. In the application, the modified copper oxide nanosieve is grafted with linoleic acid on the surface by using a silane coupling agent. In the synthetic ester insulating oil, the long-chain alkyl on the surface of the linoleic acid can improve the lipophilicity of the nanosieve, reduce agglomeration, and increase the number of micro interfaces in the insulating oil through the combined action of the copper oxide nanosieve and the linoleic acid, thereby hindering the direct passing of current, improving the alternating current insulation strength of the insulating oil, and expanding the application field of the insulating oil.

Description

Technical Field

[0001] This invention relates to the field of insulating oil, and more particularly to a modified copper oxide nanosieve, a synthetic ester insulating oil, and a method for preparing the same. Background Technology

[0002] Insulating oil is an important insulating medium in transformers. It is mainly composed of compounds such as alkanes, cycloalkanes, and aromatic unsaturated hydrocarbons, and possesses excellent insulation properties, low dielectric loss, superior cooling performance, and strong maintenance and corrosion resistance. Insulating oils are mainly classified into synthetic ester insulating oils, natural ester insulating oils, and mineral insulating oils. Among them, synthetic ester insulating oils have high dielectric strength, can withstand higher voltages than natural ester and mineral insulating oils, have a higher breakdown voltage, and are less corrosive to cable materials. They are primarily used for insulation in high-voltage electrical equipment.

[0003] However, synthetic ester insulating oils still have room for improvement in certain performance indicators, particularly in AC insulation strength. To enhance the AC insulation strength of insulating oils, researchers have begun to explore the introduction of nanomaterials into them. The aim is to find technologies that can effectively reduce the high AC insulation strength of synthetic ester insulating oils to meet application requirements. Summary of the Invention

[0004] This invention provides a modified copper oxide nanosieve, a synthetic ester insulating oil, and a method for preparing the same. By grafting linoleic acid onto the surface of the copper oxide nanosieve, the dispersibility of the nanosieve in the synthetic ester insulating oil is improved, while its insulation strength is enhanced.

[0005] To address the aforementioned technical problems, one objective of this invention is to provide a method for preparing modified copper oxide nanosieves, comprising the following steps:

[0006] (1) Disperse copper sulfate in an aqueous ethanol solution with a volume concentration of 50%-70%, add sodium hydroxide to adjust the pH value to 7.5-8 to obtain a sol, heat and stir the sol to react, dry it under vacuum, calcine it in an inert gas atmosphere, wash it, dry it under vacuum, and sieve it to obtain copper oxide nanosieves.

[0007] (2) Disperse the silane coupling agent in solvent A to obtain an activator. Spray the activator evenly onto the surface of copper oxide nanosieve, react at constant temperature and humidity, wash, and vacuum dry to obtain activated tin oxide nanosieve.

[0008] (3) The activated copper oxide nanosieve and linoleic acid were mixed in solvent B, heated and stirred to react, centrifuged, washed and vacuum dried to obtain the modified copper oxide nanosieve.

[0009] The modified copper oxide nanosieve of this application is prepared by the sol-gel method. The nanosieve has uniform pore size distribution, good chemical stability and high purity. Using a silane coupling agent as a connecting bridge between the copper oxide nanosieve and linoleic acid, linoleic acid is grafted onto the surface of the nanosieve, which can simultaneously have high specific surface area and surface efficiency. When added to synthetic ester insulating oil, the long-chain hydrocarbon groups on the surface of linoleic acid can improve the oleophilicity of the nanosieve and reduce agglomeration. Moreover, through the synergistic effect of copper oxide nanosieve and linoleic acid, the number of micro-interfaces in the insulating oil is increased, which hinders the direct passage of current and improves the insulation strength of the insulating oil.

[0010] As a preferred embodiment, in step (1), the mass ratio of copper sulfate to aqueous ethanol solution is 1:(4-6).

[0011] As a preferred embodiment, in step (2), the mass ratio of the activator to the copper oxide nanosieve is 1:(1-3).

[0012] As a preferred embodiment, in step (3), the mass ratio of the activated copper oxide nanosieve to linoleic acid is 1:(2-4).

[0013] As a preferred embodiment, in step (2), solvent A is acetone, and the mass concentration of the silane coupling agent in the activator is 1wt%-3wt%.

[0014] As a preferred embodiment, in step (3), solvent B is n-hexane, and the mass ratio of the activated copper oxide nanosieve to solvent B is 1:(3-5).

[0015] As a preferred option, in step (1), the heating and stirring reaction temperature is 40-50℃ and the time is 12-24h.

[0016] As a preferred embodiment, in step (1), the calcination temperature is 800-900℃ and the time is 180-240min.

[0017] As a preferred embodiment, in step (1), the size of the copper oxide nanosieve is 80-120 nm.

[0018] As a preferred option, in step (2), the constant temperature and humidity reaction temperature is 70-80℃, the humidity is 60%-70%, and the time is 10-15h.

[0019] As a preferred option, in step (3), the heating and stirring reaction temperature is 80-100℃ and the time is 10-20h.

[0020] As a preferred embodiment, in steps (1), (2), and (3), the vacuum drying temperature is 40-60℃ and the time is 12-48h.

[0021] As a preferred embodiment, the silane coupling agent is an epoxy silane coupling agent.

[0022] As a preferred embodiment, the inert gas is argon.

[0023] To address the aforementioned technical problems, a second objective of this invention is to provide a modified copper oxide nanosieve.

[0024] To address the aforementioned technical problems, a third objective of this invention is to provide a synthetic ester insulating oil containing modified copper oxide nanosieves, wherein the mass fraction of the modified copper oxide nanosieves is 0.1 wt% to 0.4 wt%.

[0025] When modified copper oxide nanosieves are added to synthetic ester insulating oil, they exhibit high compatibility with the oil, increasing the number of micro-interfaces and hindering the direct passage of current, thus effectively improving the AC insulation strength of the synthetic ester insulating oil. Controlling the amount of modified copper oxide nanosieves added can prevent excessive addition and agglomeration, which would reduce the contact area between the nanosieves and the insulating oil. Furthermore, agglomerated modified copper oxide nanosieves can generate sol impurities during operation, affecting the insulation strength of the insulating oil.

[0026] As a preferred option, it also includes 0-5 wt% additives and the balance MTE insulating oil.

[0027] As a preferred embodiment, the additive is at least one of preservatives, antifoaming agents, deemulsifiers, detergents, and antioxidants.

[0028] Compared with the prior art, the present invention has the following beneficial effects:

[0029] The modified copper oxide nanosieve of this application has a uniform pore size distribution, good chemical stability and high purity. By grafting linoleic acid onto the surface of the nanosieve using a silane coupling agent, it can simultaneously have a high specific surface area and surface efficiency. When added to synthetic ester insulating oil, the long-chain hydrocarbon groups on the surface of linoleic acid can improve the oleophilicity of the nanosieve and reduce agglomeration. Furthermore, through the combined action of the copper oxide nanosieve and linoleic acid, the number of micro-interfaces in the insulating oil is increased, hindering the direct passage of current and improving the insulation strength of the insulating oil. Detailed Implementation

[0030] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. 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 of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0031] It should be understood that the terminology used in this invention is merely for describing particular embodiments and is not intended to limit the invention. Furthermore, with respect to numerical ranges in this invention, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. Any stated value or intermediate value within a stated range, as well as each smaller range between any other stated value or intermediate value within said range, is also included in this invention. The upper and lower limits of these smaller ranges may be independently included or excluded from the range.

[0032] Unless otherwise stated, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art. While only preferred methods and materials have been described herein, any methods and materials similar or equivalent to those described herein may be used in the implementation or testing of this invention. All references to this specification are incorporated by way of citation to disclose and describe methods and / or materials associated with those references. In the event of any conflict with any incorporated reference, the content of this specification shall prevail.

[0033] Various modifications and variations can be made to the specific embodiments described in this specification without departing from the scope or spirit of the invention, as will be apparent to those skilled in the art. Other embodiments derived from this specification will also be readily apparent to those skilled in the art. This specification and embodiments are merely exemplary.

[0034] As used in this article:

[0035] "Prepared from" is synonymous with "comprising". The terms "comprising", "including", "having", "containing", or any other variations thereof as used herein are intended to cover non-exclusive inclusion. For example, a composition, step, method, article, or apparatus that includes the listed elements is not necessarily limited to those elements, but may include other elements not expressly listed or elements inherent to such composition, step, method, article, or apparatus.

[0036] The conjunction "composed of..." excludes any unspecified elements, steps, or components. If used in a claim, this phrase makes the claim closed, excluding materials other than those described, except for associated conventional impurities. When the phrase "composed of..." appears in a clause of the body of a claim rather than immediately following it, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0037] When a quantity, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper and lower preferred values, this should be understood as specifically inventing all ranges formed by any pair of any upper or preferred value with any lower or preferred value, regardless of whether such range is invented individually. When numerical ranges are described herein, unless otherwise stated, the range is intended to include its endpoints and all integers and fractions within that range.

[0038] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0039] "Parts by mass" refers to the basic unit of measurement that expresses the proportional relationship of the mass of multiple components. One part can represent any unit mass. It is important to understand that, unlike the number of parts by mass, the sum of the parts by mass of all components is not limited to 100 parts.

[0040] "And / or" is used to indicate that one or both of the described situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0041] In the description of this invention, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom", etc., indicating orientation or positional relationship are only for the convenience of describing this invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of this invention.

[0042] To further illustrate the present invention, the following detailed description, in conjunction with embodiments, of the composite sheet with a pre-formed sintering layer on its surface, its preparation method, and its application, is provided by the present invention. However, these descriptions should not be construed as limiting the scope of protection of the present invention. Unless otherwise specified, the raw materials used in the following embodiments and comparative examples are commercially available, and the same raw materials were used in parallel experiments.

[0043] Example 1

[0044] A method for preparing a synthetic ester insulating oil includes the following steps:

[0045] (1) Take 15g of copper sulfate solid (CuSO4·5H2O) in 80mL of ethanol aqueous solution, stir evenly, the volume concentration of ethanol aqueous solution is 65%, add sodium hydroxide to adjust the pH value to 7.5 to obtain sodium hydroxide sol, heat the sol in an oil bath to 45℃ and stir continuously for 18h to obtain gel, then vacuum dry in 55℃ for 12h, place in a tube furnace and calcine in an argon atmosphere, the calcination temperature is 850℃ and the calcination time is 200min, after cooling, sieve, use template method to control the sieve hole size to 100±10nm to obtain copper oxide nanosieve;

[0046] (2) Add 3 ml of epoxy silane coupling agent KH560 to 200 mL of acetone, heat to 50 °C and stir for 1 h to dissolve and obtain activator. Wash the impurities on the surface of copper oxide nanosieve with ethanol, dry in a vacuum drying oven at 40 °C for 24 h, and uniformly coat the surface of copper oxide nanosieve by spraying. The mass ratio of activator to tin oxide nanosieve is 1:3. React in a constant temperature and humidity environment of 75 °C and 65% for 12 h, then wash with ethanol and dry in a vacuum drying oven at 50 °C for 18 h to obtain activated copper oxide nanosieve.

[0047] (3) Mix 15g of activated copper oxide nanosieve and 40g of linoleic acid in 60mL of n-hexane, heat to 90℃ and stir continuously for 15h to promote the amidation reaction between the carboxyl group of linoleic acid and the amino group on the surface of copper oxide nanosieve. After the reaction, centrifuge to separate the liquid, wash the solid product with n-hexane, and dry it at 40℃ in a vacuum dryer for 30h to obtain modified copper oxide nanosieve.

[0048] (4) Mix 0.1 wt% modified copper oxide nanosieve and the remaining MTE insulating oil, and use a high-speed mixer at a speed of 1200 rpm to disperse the mixed oil sample at high speed for 4 hours. After vacuum drying at 35°C for 18 hours, synthetic ester insulating oil is obtained.

[0049] Example 2

[0050] A method for preparing synthetic ester insulating oil, wherein each step and the reagents, equipment and process parameters used in each step are the same as in Example 1, except that in step (4), the content of modified copper oxide nanosieve is 0.2 wt%.

[0051] Example 3

[0052] A method for preparing synthetic ester insulating oil, wherein each step and the reagents, equipment and process parameters used in each step are the same as in Example 1, except that in step (4), the content of modified copper oxide nanosieve is 0.4 wt%.

[0053] Comparative Example 1

[0054] A method for preparing a synthetic ester insulating oil, wherein each step and the reagents, equipment and process parameters used in each step are the same as in Example 2, except that in step (4), the content of modified copper oxide nanosieve is 0.05wt%.

[0055] Comparative Example 2

[0056] A method for preparing synthetic ester insulating oil, wherein each step and the reagents, equipment and process parameters used in each step are the same as in Example 2, except that in step (4), the content of modified copper oxide nanosieve is 0.5 wt%.

[0057] Comparative Example 3

[0058] A method for preparing synthetic ester insulating oil, wherein each step and the reagents, equipment and process parameters used in each step are the same as those in Example 2, except that in step (3), the activated copper oxide nanosieve is replaced by an equal amount of the copper oxide nanosieve in step (1).

[0059] Comparative Example 4

[0060] A method for preparing synthetic ester insulating oil, wherein each step and the reagents, equipment and process parameters used in each step are the same as in Example 2, except that in step (4), the modified copper oxide nanosieve is replaced by an equal amount of activated copper oxide nanosieve.

[0061] Comparative Example 5

[0062] A method for preparing synthetic ester insulating oil, wherein each step and the reagents, equipment and process parameters used in each step are the same as in Example 2, except that in step (3), linoleic acid is replaced by an equal amount of arachidonic acid.

[0063] Comparative Example 6

[0064] A method for preparing synthetic ester insulating oil, wherein each step and the reagents, equipment and process parameters used in each step are the same as those in Example 2, except that in step (2), the copper oxide nanosieve is replaced by an equal amount of nano copper oxide of Zhejiang Jiupeng New Materials model CY-Cu01.

[0065] Comparative Example 7

[0066] A method for preparing mineral insulating oil, wherein each step and the reagents, equipment and process parameters used in each step are the same as those in Example 2, except that in step (4), MTE insulating oil is replaced by an equal amount of Karamay #25 mineral oil.

[0067] Comparative Example 8

[0068] A method for preparing synthetic ester insulating oil, wherein each step and the reagents, equipment and process parameters used in each step are the same as in Example 2, the difference being that in step (1), 15g of copper sulfate (CuSO4·5H2O) and 80mL of deionized water are mixed, then 30mL of ethylene glycol is added, sodium hydroxide is added to adjust the pH of the solution to 8, the solution is heated to 65℃ in an oil bath and reacted for 24h, cooled to room temperature, the solution is separated by centrifugation, the solid is washed with ethanol, placed in a vacuum drying oven and dried at 55℃ for 12h, and then placed in a tube furnace and calcined in an argon atmosphere at a calcination temperature of 850℃ for 200min, cooled and sieved, the sieve aperture size is controlled to be 100±10nm using a template method to obtain copper oxide nanosieves.

[0069] Comparative Example 9

[0070] A method for preparing synthetic ester insulating oil, wherein each step and the reagents, equipment and process parameters used in each step are the same as in Example 2, except that in step (4), the amount of modified copper oxide nanosieve added is 0.

[0071] Comparative Example 10

[0072] A method for preparing mineral insulating oil, wherein each step and the reagents, equipment and process parameters used in each step are the same as those in Example 2, except that in step (4), MTE insulating oil is replaced by an equal amount of Karamay #25 mineral oil, and the amount of modified copper oxide nanosieve added is 0.

[0073] Performance testing

[0074] Referring to IEC 60156-2018 and DL / T 421-2009 standards, the breakdown voltage tester and insulating oil volume resistivity meter of model LJC-100KV were used to conduct power frequency breakdown voltage tests and volume resistivity measurements on the insulating oils of the examples and comparative examples. The test results are shown in Table 1 below.

[0075] Table 1 - Performance test results of insulating oils in the embodiments and comparative examples of this application

[0076]

[0077]

[0078] Comparing the performance test results of Examples 1-3 and Comparative Examples 1-2 in Table 1, it can be seen that the amount of modified copper oxide nanosieve added in Comparative Example 1 is relatively low, which has limited effect on improving the AC insulation strength of synthetic ester insulating oil. In Comparative Example 2, the amount of modified copper oxide nanosieve added is too high, which easily leads to agglomeration, resulting in a reduction in the contact area between the nanosieve and the synthetic ester insulating oil, and thus a lower insulation strength of the synthetic ester insulating oil.

[0079] Comparing the performance test results of Example 2 and Comparative Examples 3-4 in Table 1, it can be seen that in Example 2, the silane coupling agent acts as a linker between the copper oxide nanosieve and linoleic acid, improving their compatibility. The long-chain hydrocarbon groups carried by linoleic acid can improve the dispersibility of the nanosieve in the synthetic ester insulating oil. Furthermore, the combined effect of the copper oxide nanosieve and linoleic acid increases the number of micro-interfaces in the insulating oil, hindering the direct passage of current and improving the insulation strength of the insulating oil. In contrast, the copper oxide nanosieve in Comparative Example 3 was not activated by the silane coupling agent, resulting in a low content of linoleic acid grafted onto the surface of the nanosieve. In Comparative Example 4, the activated copper oxide nanosieve did not have linoleic acid grafted onto its surface, leading to uneven dispersion of the nanosieve in the synthetic ester insulating oil, easy agglomeration, and a significant decrease in the insulation strength of the insulating oil.

[0080] Based on the performance test results of Example 2 and Comparative Examples 6 and 8 in Table 1, it can be seen that Comparative Example 6 uses solid single-crystal nano-copper oxide, which has a low relative specific surface area and few sites on the surface that can be modified with linoleic acid, resulting in limited improvement in the AC insulation strength of the insulating oil; Comparative Example 8 uses a water-soluble method to prepare copper oxide nanosieves, resulting in uneven pore size distribution and low chemical purity, which can easily introduce impurities into the synthesized ester insulating oil and have a negative impact.

[0081] The specific embodiments described above further illustrate the purpose, technical solution, and beneficial effects of the present invention. It should be understood that the above descriptions are merely specific embodiments of the present invention and are not intended to limit the scope of protection of the present invention. In particular, it should be noted that any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of the present invention should be included within the scope of protection of the present invention for those skilled in the art.

Claims

1. A synthetic ester insulating oil characterized in that, The modified copper oxide nanosieve has a mass fraction of 0.1wt%-0.4wt%, and the preparation method of the modified copper oxide nanosieve comprises the following steps: (1) taking copper sulfate dispersed in an ethanol aqueous solution with a volume concentration of 50%-70%, adding sodium hydroxide to adjust the pH value to 7.5-8 to obtain a sol, heating and stirring the sol to react, vacuum drying, calcining in an inert gas atmosphere, washing, and vacuum drying and sieving to obtain copper oxide nanosieve; (2) dispersing a silane coupling agent in a solvent A to obtain an activator, uniformly coating the activator on the surface of the copper oxide nanosieve in a spraying manner, constant temperature and humidity reaction, washing, and vacuum drying to obtain activated copper oxide nanosieve; (3) mixing the activated copper oxide nanosieve and linoleic acid in a solvent B, heating and stirring to react, centrifuging, washing, and vacuum drying to obtain modified copper oxide nanosieve; In step (1), the size of the copper oxide nanosieve is 80-120 nm.

2. A synthetic ester insulating oil according to claim 1, wherein At least one of the following a)-c) is met: a) in step (1), the mass ratio of the copper sulfate to the ethanol aqueous solution is 1:(4-6); b) in step (2), the mass ratio of the activator to the copper oxide nanosieve is 1:(1-3); c) in step (3), the mass ratio of the activated copper oxide nanosieve to linoleic acid is 1:(2-4).

3. The synthetic ester insulating oil according to claim 1, wherein In step (2), the solvent A is acetone, and the mass concentration of the silane coupling agent in the activator is 1wt%-3wt%; in step (3), the solvent B is n-hexane, and the mass ratio of the activated copper oxide nanosieve to the solvent B is 1:(3-5).

4. The synthetic ester insulating oil of claim 1, wherein At least one of the following a)-d) is met: a) in step (1), the heating and stirring reaction temperature is 40-50 ℃, and the time is 12-24 h; b) in step (1), the calcination temperature is 800-900 ℃, and the time is 180-240 min; c) in step (2), the constant temperature and humidity reaction temperature is 70-80 ℃, the humidity is 60%-70%, and the time is 10-15 h; d) in step (3), the heating and stirring reaction temperature is 80-100 ℃, and the time is 10-20 h.

5. The synthetic ester insulating oil of claim 1, wherein In steps (1), (2), and (3), the vacuum drying temperature is 40-60 ℃, and the time is 12-48 h.

6. The synthetic ester insulating oil of claim 1, wherein The silane coupling agent is an epoxy silane coupling agent.

7. The synthetic ester insulating oil according to claim 1, wherein 0-5wt% of an additive and the rest of MTE insulating oil are further included.

8. The synthetic ester insulating oil according to claim 7, characterized by The additive is at least one of a preservative, an antifoaming agent, an antiemulsifier, a cleaning agent, and an antioxidant.

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