Modified copper oxide nano sieve, synthetic ester insulating oil and preparation method of synthetic ester insulating oil

Abstract

The invention discloses a modified copper oxide nano sieve, synthetic ester insulating oil and a preparation method thereof, and relates to the field of insulating oil. The synthetic ester insulating oil comprises 0.1 wt%-0.4 wt% of a modified copper oxide nano-sieve. The preparation method of the modified copper oxide nano-sieve comprises the following steps: (1) preparing the copper oxide nano-sieve by adopting a sol-gel method; (2) coating the surface of the copper oxide nano sieve with a silane coupling agent for activation; and (3) heating the activated copper oxide nano sieve and linoleic acid to react, thereby obtaining the copper oxide nano sieve. According to the modified copper oxide nano-sieve, linoleic acid is grafted on the surface of the modified copper oxide nano-sieve by utilizing a silane coupling agent, in synthetic ester insulating oil, long-chain alkyl on the surface of linoleic acid can improve lipophilicity of the nano-sieve and reduce agglomeration, and through combined action of the copper oxide nano-sieve and linoleic acid, the number of tiny interfaces in the insulating oil is increased, direct passing of current is hindered, and the insulating property of the nano-sieve is improved. The alternating-current insulating strength of the insulating oil is improved and the application field of the insulating oil is expanded.

Description

Technical Field

[0001] The invention relates to the field of insulating oil, and in particular to a modified copper oxide nanosieve, a synthetic ester insulating oil and a preparation method thereof. Background Art

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

[0003] However, pure synthetic ester insulating oil still needs to be improved in some performance indicators, especially in terms of AC insulation strength. In order to improve the AC insulation strength of insulating oil, researchers began to try to introduce nanomaterials into insulating oil, and they need to find technologies that can effectively reduce the high AC insulation strength of synthetic ester insulating oil to meet application requirements. Summary of the invention

[0004] The invention provides a modified copper oxide nanosieve, a synthetic ester insulating oil and a preparation method thereof. Linoleic acid is grafted onto the surface of the copper oxide nanosieve to improve the dispersibility of the nanosieve in the synthetic ester insulating oil and simultaneously enhance the insulation strength thereof.

[0005] In order to solve the above technical problems, one of the purposes of the present invention is to provide a method for preparing a modified copper oxide nanosieve, comprising the following steps:

[0006] (1) dispersing copper sulfate in an ethanol aqueous solution with a volume concentration of 50% to 70%, adding sodium hydroxide to adjust the pH value to 7.5 to 8 to obtain a sol, heating and stirring the sol for reaction, vacuum drying, calcining in an inert gas atmosphere, washing, vacuum drying, and sieving to obtain a copper oxide nanosieve;

[0007] (2) dispersing a silane coupling agent in solvent A to obtain an activator, uniformly coating the activator on the surface of the copper oxide nanosieve by spraying, reacting at a constant temperature and humidity, washing, and vacuum drying to obtain an activated tin oxide nanosieve;

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

[0009] The modified copper oxide nanosieve of the present application is prepared by a sol-gel method, and the nanosieve has uniform pore size distribution, good chemical stability and high purity. A silane coupling agent is used as a connecting bridge between the copper oxide nanosieve and linoleic acid, and linoleic acid is grafted on the surface of the nanosieve, so that the nanosieve has both high specific surface area and surface efficiency. When added to synthetic ester insulating oil, the long-chain hydrocarbon group on the surface of linoleic acid can improve the lipophilicity of the nanosieve and reduce agglomeration. The copper oxide nanosieve and linoleic acid work together to increase the number of tiny interfaces in the insulating oil, hinder the direct passage of current, and improve the insulating strength of the insulating oil.

[0010] As a preferred embodiment, in step (1), the mass ratio of copper sulfate to ethanol aqueous 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 embodiment, in step (1), the heating and stirring reaction temperature is 40-50°C and the time is 12-24h.

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

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

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

[0019] As a preferred embodiment, in step (3), the heating and stirring reaction temperature is 80-100°C and the time is 10-20 hours.

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

[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] In order to solve the above technical problems, the second purpose of the present invention is to provide a modified copper oxide nanosieve.

[0024] In order to solve the above technical problems, the third object of the present invention provides a synthetic ester insulating oil containing modified copper oxide nanosieve, wherein the mass fraction of the modified copper oxide nanosieve is 0.1wt%-0.4wt%.

[0025] When the modified copper oxide nanosieve is added to the synthetic ester insulating oil, the modified copper oxide nanosieve has a high degree of compatibility with the insulating oil, can increase the number of tiny interfaces in the insulating oil, hinder the direct passage of current, and effectively improve the AC insulation strength of the synthetic ester insulating oil; by controlling the amount of the modified copper oxide nanosieve added, it is possible to avoid agglomeration of the modified copper oxide nanosieve due to excessive addition, which will cause the contact area between the nanosieve and the insulating oil to decrease, and the agglomerated modified copper oxide nanosieve will also generate sol impurities during operation, affecting the insulation strength of the insulating oil.

[0026] As a preferred solution, the invention further comprises 0-5wt% additives and the balance is MTE insulating oil.

[0027] As a preferred embodiment, the additive is at least one of a preservative, an antifoaming agent, an anti-emulsifier, a detergent, and an antioxidant.

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

[0029] The modified copper oxide nanosieve of the present application has uniform pore size distribution, good chemical stability and high purity. Linoleic acid is grafted on the surface of the nanosieve using a silane coupling agent, so that it can have both high specific surface area and surface efficiency. When added to synthetic ester insulating oil, the long-chain hydrocarbon group on the surface of linoleic acid can improve the lipophilicity of the nanosieve and reduce agglomeration. The copper oxide nanosieve and linoleic acid work together to increase the number of tiny interfaces in the insulating oil, hinder the direct passage of current, and improve the insulating strength of the insulating oil. DETAILED DESCRIPTION

[0030] The following will be combined with the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0031] It should be understood that the terms described in the present invention are only for describing a particular embodiment and are not intended to limit the present invention. In addition, for the numerical range in the present invention, it should be understood that each intermediate value between the upper and lower limits of the scope is also specifically disclosed. The intermediate value in any stated value or stated range, and each smaller range between any other stated value or intermediate value in the described range is also included in the present invention. The upper and lower limits of these smaller ranges can be independently included or excluded in the scope.

[0032] Unless otherwise indicated, all technical and scientific terms used herein have the same meanings as those generally understood by those skilled in the art. Although the present invention describes only preferred methods and materials, any methods and materials similar or equivalent to those described herein may also be used in the implementation or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of a conflict with any incorporated document, the content of this specification shall prevail.

[0033] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments of the present invention description without departing from the scope or spirit of the present invention. Other embodiments derived from the present invention description will be apparent to those skilled in the art. The present invention description and examples are exemplary only.

[0034] As used herein:

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

[0036] The conjunction "consisting of excludes any unspecified element, step, or component. If used in a claim, this phrase renders the claim closed-ended so that it does not include materials other than those described, except for conventional impurities associated therewith. When the phrase "consisting of" appears in a clause of the body of a claim rather than immediately following the subject matter, it limits only the elements described in that clause; other elements are not excluded from the claim as a whole.

[0037] When an amount, concentration, or other value or parameter is expressed as a range, a preferred range, or a range defined by a series of upper preferred values ​​and lower preferred values, this should be understood to specifically invent all ranges formed by any pairing of any upper range limit or preferred value with any lower range limit or preferred value, regardless of whether the range is invented separately. When a numerical range is described in this article, unless otherwise stated, the range is intended to include its end values ​​and all integers and fractions within the range.

[0038] In these examples, parts and percentages are by mass unless otherwise indicated.

[0039] "Parts by mass" refers to the basic unit of measurement that indicates the proportional relationship of the masses of multiple components. 1 part can represent any unit mass. It should not be misunderstood 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 stated situations may occur, for example, A and / or B includes (A and B) and (A or B).

[0041] In the description of the present invention, it is necessary to understand that the terms "up", "down", "left", "right", "top", "bottom", etc., indicating directions or positional relationships, are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific direction, be constructed and operated in a specific direction, and therefore cannot be understood as a limitation on the present invention.

[0042] In order to further illustrate the present invention, the composite sheet with a pre-sintered layer on the surface provided by the present invention and its preparation method and application are described in detail in combination with the examples below, but they should not be understood as limiting the scope of protection of the present invention. The raw materials used in the following examples and comparative examples of the present application are all commercially available unless otherwise specified, and the same raw materials are used in parallel experiments.

[0043] Example 1

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

[0045] (1) 15 g of copper sulfate solid (CuSO4·5H2O) was dissolved in 80 mL of ethanol aqueous solution and stirred evenly. The volume concentration of the ethanol aqueous solution was 65%. Sodium hydroxide was added to adjust the pH value to 7.5 to obtain a sodium hydroxide sol. The sol was heated to 45° C. in an oil bath and stirred for 18 h. The obtained gel was then vacuum dried at 55° C. for 12 h and calcined in a tube furnace in an argon atmosphere at a calcination temperature of 850° C. for 200 min. After cooling, the gel was sieved and the mesh size was controlled to be 100±10 nm using a template method to obtain a copper oxide nanosieve.

[0046] (2) 3 ml of epoxy silane coupling agent KH560 was added to 200 mL of acetone, heated to 50° C. and stirred for 1 h to dissolve the activator, and impurities on the surface of the copper oxide nanosieve were washed with ethanol, dried in a vacuum drying oven at 40° C. for 24 h, and the activator was evenly coated on the surface of the copper oxide nanosieve by spraying, wherein the mass ratio of the activator to the tin oxide nanosieve was 1:3, and reacted in a constant temperature and humidity environment at a temperature of 75° C. and a humidity of 65% for 12 h, then washed with ethanol, and dried in a vacuum drying oven at 50° C. for 18 h to obtain an activated copper oxide nanosieve;

[0047] (3) 15 g of activated copper oxide nanosieve and 40 g of linoleic acid were mixed in 60 mL of n-hexane, heated to 90° C. and stirred for 15 h to promote the amidation reaction between the carboxyl group of linoleic acid and the amino group on the surface of the copper oxide nanosieve. After the reaction, the liquid was centrifuged and separated, and the solid product was washed with n-hexane and dried in a vacuum dryer at 40° C. for 30 h to obtain a modified copper oxide nanosieve;

[0048] (4) 0.1 wt% of the modified copper oxide nanosieve and the remaining amount of MTE insulating oil were mixed, and the mixed oil sample was subjected to high-speed dispersion treatment at a speed of 1200 rpm using a high-speed stirrer for 4 h. After vacuum drying at a temperature of 35° C. for 18 h, a synthetic ester insulating oil was 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 those in Example 1, except that in step (4), the content of the modified copper oxide nanosieve is 0.2wt%.

[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 those in Example 1, except that in step (4), the content of the modified copper oxide nanosieve is 0.4wt%.

[0053] Comparative Example 1

[0054] 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 (4), the content of the 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 those in Example 2, except that in step (4), the content of the modified copper oxide nanosieve is 0.5wt%.

[0057] Comparative Example 3

[0058] 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 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 a 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 (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 those in Example 2, except that in step (3), linoleic acid is replaced by arachidonic acid in an equal amount.

[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 model CY-Cu01 produced by Zhejiang Jiupeng New Materials.

[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 a 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 (1), 15 g of copper sulfate (CuSO4·5H2O) and 80 mL of deionized water are mixed, 30 ml of ethylene glycol is added, sodium hydroxide is added to adjust the pH value of the solution to 8, the solution is heated to 65° C. in an oil bath for reaction for 24 h, cooled to room temperature, the solution is centrifuged, the solid is washed with ethanol, placed in a vacuum drying oven at 55° C. for drying for 12 h, then placed in a tubular furnace, calcined in an argon atmosphere, the calcination temperature is 850° C., the calcination time is 200 min, and after cooling, the solution is sieved, and the sieve hole size is controlled to be 100±10 nm using a template method to obtain a copper oxide nanosieve.

[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 those 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), the 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 LJC-100KV breakdown voltage tester and the insulating oil volume resistivity tester were used to perform power frequency breakdown voltage test and volume resistivity measurement on the insulating oils of the embodiments and comparative examples. The test results are shown in Table 1 below.

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

[0076]

[0077]

[0078] By 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 low, and the improvement of the AC insulation strength of the synthetic ester insulating oil is limited. The amount of modified copper oxide nanosieve added in Comparative Example 2 is too much, and agglomeration is prone to occur, resulting in a reduction in the contact area between the nanosieve and the synthetic ester insulating oil, resulting in a lower insulation strength of the synthetic ester insulating oil.

[0079] By comparing the performance test results of Example 2 and Comparative Examples 3-4 in Table 1, it can be seen that the silane coupling agent used in Example 2 plays a connecting role in the copper oxide nanosieve and linoleic acid, improves the compatibility between the two, and the long-chain hydrocarbon group carried by linoleic acid can improve the dispersibility of the nanosieve in the synthetic ester insulating oil. In addition, the copper oxide nanosieve and linoleic acid work together to increase the number of tiny interfaces in the insulating oil, hinder the direct passage of current, and improve the insulating strength of the insulating oil; while the copper oxide nanosieve of Comparative Example 3 is not activated by silane coupling agent, and the content of linoleic acid grafted on the surface of the nanosieve is low. In Comparative Example 4, the activated copper oxide nanosieve is not grafted with linoleic acid on the surface, resulting in uneven dispersion of the nanosieve in the synthetic ester insulating oil, easy agglomeration, and a significant decrease in the insulating strength of the insulating oil.

[0080] Combining 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 for modifying linoleic acid on the surface, resulting in limited improvement in the AC insulation strength of the insulating oil; Comparative Example 8 uses a water-soluble method to prepare the copper oxide nanosieve, resulting in uneven pore size distribution of the synthesis and low chemical purity, which is easy to introduce impurities into the synthetic ester insulating oil and has a negative impact.

[0081] The specific embodiments described above further illustrate the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above description is only a specific embodiment of the present invention and is not intended to limit the scope of protection of the present invention. It is particularly pointed out that for those skilled in the art, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention should be included in the scope of protection of the present invention.

Claims

1. A method for preparing a modified copper oxide nanosieve, characterized in that: The following steps are involved: (1) dispersing copper sulfate in an ethanol aqueous solution with a volume concentration of 50% to 70%, adding sodium hydroxide to adjust the pH value to 7.5 to 8 to obtain a sol, heating and stirring the sol for reaction, vacuum drying, calcining in an inert gas atmosphere, washing, vacuum drying, and sieving to obtain a copper oxide nanosieve; (2) dispersing a silane coupling agent in solvent A to obtain an activator, uniformly coating the activator on the surface of the copper oxide nanosieve by spraying, reacting at a constant temperature and humidity, washing, and vacuum drying to obtain an activated tin oxide nanosieve; (3) The activated copper oxide nanosieve and linoleic acid are mixed in solvent B, heated and stirred for reaction, centrifuged, washed, and vacuum dried to obtain a modified copper oxide nanosieve.

2. The method for preparing a modified copper oxide nanosieve according to claim 1, characterized in that: Satisfy at least one of the following a)-c): 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 method for preparing a modified copper oxide nanosieve according to claim 1, characterized in that: 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 method for preparing a modified copper oxide nanosieve according to claim 1, characterized in that: Satisfy at least one of the following a)-e): a) In step (1), the heating and stirring reaction temperature is 40-50°C and the time is 12-24h; b) in step (1), the calcination temperature is 800-900° C. and the calcination time is 180-240 min; c) in step (1), the size of the copper oxide nanosieve is 80-120 nm; d) In step (2), the constant temperature and humidity reaction temperature is 70-80°C, the humidity is 60%-70%, and the time is 10-15h; e) In step (3), the heating and stirring reaction temperature is 80-100° C. and the time is 10-20 h.

5. The method for preparing a modified copper oxide nanosieve according to claim 1, characterized in that: In steps (1), (2) and (3), the vacuum drying temperature is 40-60° C. and the time is 12-48 hours.

6. The method for preparing a modified copper oxide nanosieve according to claim 1, characterized in that: The silane coupling agent is an epoxy silane coupling agent.

7. A modified copper oxide nanosieve prepared by the preparation method of the modified copper oxide nanosieve according to any one of claims 1 to 6.

8. A synthetic ester insulating oil, characterized in that: Contains the modified copper oxide nanosieve as claimed in claim 7, wherein the mass fraction of the modified copper oxide nanosieve is 0.1wt%-0.4wt%.

9. The synthetic ester insulating oil according to claim 8, characterized in that It also includes 0-5wt% additives and the balance is MTE insulating oil.

10. The synthetic ester insulating oil according to claim 8, characterized in that The additive is at least one of a preservative, an antifoaming agent, an anti-emulsifier, a detergent, and an antioxidant.

Images