A modified tin oxide nanosieve grafted on the surface of linoleic acid and a preparation method and application thereof

Abstract

The application discloses a kind of surface grafting of linoleic acid tin oxide nanosieve and its preparation method and application, it is related to insulating oil field.Nanosieve preparation method is: using sol-gel method to prepare tin oxide nanosieve, using silane coupling agent to the surface of tin oxide nanosieve is activated treatment, then with linoleic acid reaction, silane coupling agent is as molecular bridge and grafts linoleic acid on the surface of tin oxide nanosieve, obtains modified tin oxide nanosieve.Preparing tin oxide nanosieve by sol-gel method makes that pore size distribution is uniform, and specific surface area and chemical purity are higher, and structure stability is good, utilize long-chain hydrocarbon radical of linoleic acid to improve the lipophilicity and dispersibility of nanosieve in organic solvent, so that nanosieve can efficiently capture and neutralize charge, form the barrier of hindering charge migration in insulating oil, to improve the impact insulation strength of insulating oil, expand the application field of insulating oil.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of insulating oil, in particular to a modified tin oxide nanosieve surface grafted with linoleic acid and a preparation method and application thereof. BACKGROUND

[0002] At present, researchers have prepared surface-modified titanium dioxide nanosieves and applied them to improve the electrical strength of mineral insulating oil. This nanosieve requires a specific preparation process, such as the reaction of titanium sulfate and ammonium carbonate in ammonia water, calcination, and modification with stearic acid and triethylamine, to obtain a nanosieve material with extremely high specific surface area and surface effect. Under the action of an electric field, the material can polarize and generate a large number of traps to capture free electrons in the oil, thereby delaying the formation of discharge channels and improving the breakdown voltage of the oil.

[0003] However, the preparation process of this surface-modified titanium dioxide nanosieve is complex and involves multiple steps, including reaction, separation, calcination, and modification. These steps require high operating conditions and equipment, increasing production costs and preparation difficulty. Although modifiers such as stearic acid and triethylamine can improve the compatibility of the nanosieve with insulating oil, the modification effect may be influenced by factors such as the surface properties of the nanosieve, the type and amount of modifier, resulting in insufficient dispersion and stability of the modified nanosieve in insulating oil. Although this prior art can improve the electrical strength of insulating oil, its insulation performance may be limited when facing higher voltage grades and more complex operating environments of electrical equipment. Moreover, it mainly focuses on titanium dioxide nanosieves, with little research on other types of nanosieve materials, limiting the diversity of material selection and application range. SUMMARY

[0004] The present application provides a modified tin oxide nanosieve surface grafted with linoleic acid and a preparation method and application thereof. By surface modification and grafting of linoleic acid on activated tin oxide nanosieve, the impact insulation strength of synthetic ester insulating oil can be significantly improved when applied to synthetic ester insulating oil.

[0005] To solve the above technical problems, one of the objectives of the present application provides a preparation method of a modified tin oxide nanosieve surface grafted with linoleic acid, comprising the following steps:

[0006] (1) Disperse tin chloride in an ethanol aqueous solution, adjust the pH value with a base to trigger a hydrolysis reaction, obtain a sol, heat the sol in an oil bath at 40-50℃ and stir the reaction, vacuum dry, calcine in an inert gas atmosphere, wash, vacuum dry, and sieve to obtain tin oxide nanosieve;

[0007] (2) dispersing the silane coupling agent in the solvent A to obtain a coupling agent solution, coating the coupling agent solution on the surface of the tin oxide nanosieve in a spraying manner, and reacting in a constant temperature and humidity environment with a temperature of 70-90 DEG C and a humidity of 50-70%, washing, and vacuum drying to obtain the activated tin oxide nanosieve;

[0008] (3) mixing the activated tin oxide nanosieve and the linoleic acid in the solvent B, heating to 70-90 DEG C and stirring to react, centrifuging, washing the precipitate, and vacuum drying to obtain the modified tin oxide nanosieve grafted with the linoleic acid on the surface.

[0009] By using the above scheme, the tin oxide nanosieve with a porous structure is prepared by the sol-gel method, so that the prepared tin oxide nanosieve has a more uniform particle size and a more accurate pore size distribution, and has a higher chemical purity and a better structural stability. The use of the silane coupling agent for the activation treatment of the tin oxide nanosieve can play a role of a "molecular bridge" between the nanosieve and the linoleic acid, and significantly improve the compatibility between the two. After the surface grafting of the linoleic acid, the long-chain alkyl group of the linoleic acid is carried on the surface, the lipophilicity and the dispersibility in the organic solvent are improved, and the charges carried on the surface can capture and neutralize the charges by introducing the tin oxide nanosieve and the linoleic acid, so that a barrier to charge migration is formed in the insulating oil, thereby improving the impulse insulation strength of the insulating oil.

[0010] As a preferred scheme, in step (1), the size of the tin oxide nanosieve is 50-200 nm.

[0011] As a preferred scheme, in step (1), the mass ratio of the tin chloride and the ethanol aqueous solution is 1:(4-6), and / or, the pH value is adjusted to 7.8-8.2 by adding an alkali.

[0012] As a preferred scheme, in step (1), the volume concentration of the ethanol aqueous solution is 50%-80%.

[0013] As a preferred scheme, in step (1), the alkali is sodium hydroxide.

[0014] As a preferred scheme, in step (1), the oil bath heating reaction time is 12-24 h.

[0015] As a preferred scheme, in step (1), the inert gas is argon.

[0016] As a preferred scheme, in step (1), the calcination temperature is 850-950 DEG C, and the calcination time is 3-4 h.

[0017] As a preferred scheme, in step (1), the vacuum drying temperature is 30-50 DEG C, and the time is 24-48 h.

[0018] As a preferred solution, in step (2), the concentration of silane coupling agent in the coupling agent solution is 1wt%-3%, and the mass ratio of the coupling agent solution and tin oxide nanosheets used for spraying is 1:(2-4).

[0019] As a preferred solution, in step (2), the solvent A is acetone.

[0020] As a preferred solution, in step (2), the constant temperature and humidity reaction time is 20-28h.

[0021] As a preferred solution, in step (2), the washing solvent is ethanol.

[0022] As a preferred solution, in step (2), the vacuum drying temperature is 30-50℃, and the time is 24-48h.

[0023] As a preferred solution, in step (3), the mass ratio of the activated tin oxide nanosheets and linoleic acid is 1:(1-4).

[0024] As a preferred solution, in step (3), the mass ratio of the activated tin oxide nanosheets and solvent B is 1:(4-6).

[0025] As a preferred solution, in step (3), the solvent B is n-hexane.

[0026] As a preferred solution, in step (3), the stirring reaction time is 10-20h.

[0027] As a preferred solution, in step (3), the washing solvent is n-hexane.

[0028] As a preferred solution, in step (3), the vacuum drying temperature is 30-50℃, and the time is 24-48h.

[0029] To solve the above technical problems, the second purpose of the present application provides a tin oxide nanosheet grafted with linoleic acid on the surface.

[0030] To solve the above technical problems, the third purpose of the present application provides an application of a tin oxide nanosheet grafted with linoleic acid on the surface in the field of preparing synthetic ester insulating oil.

[0031] To solve the above technical problems, the fourth purpose of the present application provides a synthetic ester insulating oil, which comprises 0.05wt%-0.2wt% of tin oxide nanosheets grafted with linoleic acid on the surface.

[0032] As a preferred solution, it further comprises 0-5wt% of additives and the rest of MTE insulating oil.

[0033] Compared with the prior art, the present application has the following beneficial effects:

[0034] 1、The present application prepares the porous tin oxide nanosieve with uniform pore size distribution by sol-gel method, which has higher chemical purity and better structural stability, and has better impact insulation strength improvement effect on synthetic ester insulating oil than the hydrothermal method.

[0035] 2、The present application uses silane coupling agent to activate the tin oxide nanosieve, connects linoleic acid as a molecular bridge, improves the grafting rate of linoleic acid on the surface of the molecular sieve, improves the lipophilicity and dispersibility in organic solvents by using the long-chain hydrocarbon group of linoleic acid, so that the nanosieve can form a barrier to hinder charge migration in the insulating oil, thereby improving the impact insulation strength of the synthetic ester insulating oil, and the modified synthetic ester insulating oil has a wider application range and can be used in power equipment, electrical systems and other fields. DETAILED DESCRIPTION

[0036] The technical solutions in the embodiments of the present application will be clearly and completely described below in combination with the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor fall within the scope of protection of the present application.

[0037] It should be understood that the terms described in the present application are only for describing the specific embodiments, and are not used to limit the present application. In addition, for the numerical range in the present application, it should be understood that each intermediate value between the upper limit and the lower limit of the range is also specifically disclosed. Each smaller range between any stated value or intermediate value within the stated range, and any other stated value or intermediate value within the stated range, is also included in the present application. The upper limit and the lower limit of these smaller ranges can be independently included or excluded from the range.

[0038] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application pertains. Although preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein can be used in the practice or testing of the present application. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials in connection with which the documents are concerned. In the case of conflict, the content of this specification will control.

[0039] Various modifications and changes can be made to the specific implementation of the present application described in the specification without departing from the scope or spirit of the application. Other implementations of the present application will be apparent to those skilled in the art from consideration of the specification and practice of the application. The specification and examples of the present application are illustrative only.

[0040] As used in this article:

[0041] "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.

[0042] 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.

[0043] 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 the range is invented individually. For example, when the range “1–5” is invented, the described range should be interpreted as including ranges “1–4”, “1–3”, “1–2”, “1–2 and 4–5”, “1–3 and 5”, etc. 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.

[0044] In these embodiments, unless otherwise specified, the portions and percentages are all by weight.

[0045] "Parts by mass" is a basic unit of measurement that expresses the proportional relationship between the masses of multiple components. One part can represent any unit mass. If we say that component A has "a" parts by mass and component B has "b" parts by mass, it means the ratio of the mass of component A to the mass of component B is a:b. Alternatively, it can mean that the mass of component A is aK and the mass of component B is bK (where K is any number representing a multiplier). It is important to understand that, unlike the number of parts by mass, the sum of the mass parts of all components is not limited to 100 parts.

[0046] "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).

[0047] In the description of the present application, it should be understood that the terms "upper", "lower", "left", "right", "top", "bottom", etc. indicate the orientation or positional relationship, which are only for the convenience of describing the present application and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as a limitation on the present application.

[0048] In order to further illustrate the present application, the modified tin oxide nanosieve grafted with linoleic acid on the surface, the preparation method and application thereof provided by the present application are described in detail below in combination with examples, but they cannot be understood as a limitation on the protection scope of the present application. In the following examples and comparative examples of the present application, the raw materials used are commercially available, and the same raw materials are used in parallel experiments, unless otherwise specified.

[0049] Preparation Example 1

[0050] A preparation method of a modified tin oxide nanosieve grafted with linoleic acid on the surface, comprising the following steps:

[0051] (1) 10 g of tin chloride solid (SnCl4) was taken in 50 mL of ethanol with a concentration of 60% to form a uniform solution, sodium hydroxide was added to the solution to adjust the pH value to 8, and a hydroxide sol was obtained by triggering the hydrolysis reaction. The sol was moved to a reaction kettle, heated to 50°C by oil bath and continuously stirred for 12 h, and after the reaction was completed, the obtained gel was vacuum dried at 60°C for 24 h, and then placed in a tube furnace and calcined at 900°C under argon atmosphere for 180 min. After cooling, the sieve hole size was controlled to be 100±10 nm by sieving using a template method, and tin oxide nanosieve was obtained;

[0052] (2) 5 mL of epoxy silane coupling agent KH-560 was added to 250 mL of acetone and placed in a magnetic stirrer and heated to 50°C for 1 h of continuous stirring to obtain a coupling agent solution. At the same time, the impurities on the surface of the tin oxide nanosieve were washed with ethanol, and then placed in a vacuum drying oven at 40°C for constant temperature drying for 24 h. The coupling agent solution was uniformly coated on the surface of the tin oxide nanosieve in a spraying manner, wherein the mass ratio of the coupling agent solution to the tin oxide nanosieve was 1:2. Then it was placed in a constant temperature and humidity machine at a temperature of 80°C and a humidity of 60% to make the coupling agent react on the surface of the tin oxide nanosieve for 24 h. After the reaction was completed, the excess coupling agent on the surface was washed with ethanol, and then it was placed in a vacuum drying oven at 40°C for constant temperature drying for 24 h to obtain activated tin oxide nanosieve;

[0053] (3) 10 g of activated tin oxide nanosieve and 20 g of linoleic acid were mixed in 50 mL of n-hexane, the solution was heated to 80°C in a magnetic stirrer and continuously stirred for 12 h to promote the amidation reaction between the carboxyl group of linoleic acid and the amino group on the surface of the tin oxide nanosieve. After the reaction was completed, the solid product was separated from the solution using a centrifuge, and the solid product was washed with an appropriate amount of n-hexane solvent to remove unreacted linoleic acid and solvent. The washed product was placed in a vacuum dryer and dried at 30°C for 24 h to obtain a modified tin oxide nanosieve grafted with linoleic acid on the surface.

[0054] Comparative Preparation Example 1

[0055] A method for preparing a modified tin oxide nanosieve grafted with linoleic acid on the surface, each step and the reagents, equipment and process parameters used in each step are the same as those of Preparation Example 1, the difference is that in step (1), 10 g of tin chloride solid (SnCl4) is dissolved in 50 mL of deionized water, 20 ml of ethylene glycol is added as a reducing agent, and sodium hydroxide is added to adjust the pH of the solution to 8. The solution is stirred uniformly and then placed in a high-pressure reaction kettle. The solution is heated to 60°C by oil bath heating and reacts for 24 h. Tin ions are reduced to tin oxide by ethylene glycol and precipitate to form nanoparticles. After the reaction is completed, the mixture is cooled to room temperature naturally, centrifuged using a centrifuge, and the precipitate is washed with ethanol. Finally, the solid is placed in a vacuum drying oven and dried at 60°C for 12 h to obtain a nanosieve precursor. The nanosieve precursor is placed in a tube furnace and calcined at 900°C for 180 min in an argon atmosphere. After cooling, the sieve hole size is controlled to be 100±10 nm by sieving using a template method to obtain tin oxide nanosieve.

[0056] Comparative Preparation Example 2

[0057] A method for preparing a tin oxide nanosieve grafted with linoleic acid on the surface, each step and the reagents, equipment and process parameters used in each step are the same as those of Preparation Example 1, the difference is that in step (3), the activated tin oxide nanosieve is replaced with an equal amount of tin oxide nanosieve in step (1).

[0058] Comparative Preparation Example 3

[0059] A method for preparing a modified tin oxide nanosieve grafted with oleic acid on the surface, each step and the reagents, equipment and process parameters used in each step are the same as those of Preparation Example 1, the difference is that in step (3), linoleic acid is replaced with an equal amount of oleic acid.

[0060] Comparative Preparation Example 4

[0061] A preparation method of a modified nano-tin oxide surface grafted by linoleic acid, each step and the reagents, equipment and process parameters used in each step are the same as those in Preparation Example 1, the difference is that in step (2), the nano-tin oxide with a purity of 99.8% Zhejiang Jiupeng New Material CY-YHX1 nano-tin oxide is used instead of an equivalent amount.

[0062] Example 1

[0063] A synthetic ester insulating oil, the preparation method thereof comprises the following steps:

[0064] The product of Preparation Example 1 is added to MTE insulating oil, wherein the mass fraction of the product of Preparation Example 1 in the whole insulating oil is 0.05wt%, a high-speed mixer is used to disperse and treat the mixed oil sample at a speed of 1200 revolutions per minute for 4h, and then vacuum drying treatment is carried out at a temperature of 40℃ for 24h after stirring, to obtain a synthetic ester insulating oil.

[0065] Example 2

[0066] A synthetic ester insulating oil, the preparation method thereof comprises the following steps:

[0067] The product of Preparation Example 1 is added to MTE insulating oil, wherein the mass fraction of the product of Preparation Example 1 in the whole insulating oil is 0.1wt%, a high-speed mixer is used to disperse and treat the mixed oil sample at a speed of 1200 revolutions per minute for 4h, and then vacuum drying treatment is carried out at a temperature of 40℃ for 24h after stirring, to obtain a synthetic ester insulating oil.

[0068] Example 3

[0069] A synthetic ester insulating oil, the preparation method thereof comprises the following steps:

[0070] The product of Preparation Example 1 is added to MTE insulating oil, wherein the mass fraction of the product of Preparation Example 1 in the whole insulating oil is 0.15wt%, a high-speed mixer is used to disperse and treat the mixed oil sample at a speed of 1200 revolutions per minute for 4h, and then vacuum drying treatment is carried out at a temperature of 40℃ for 24h after stirring, to obtain a synthetic ester insulating oil.

[0071] Example 4

[0072] A synthetic ester insulating oil, the preparation method thereof comprises the following steps:

[0073] The product of Preparation Example 1 is added to MTE insulating oil, wherein the mass fraction of the product of Preparation Example 1 in the whole insulating oil is 0.2wt%, a high-speed mixer is used to disperse and treat the mixed oil sample at a speed of 1200 revolutions per minute for 4h, and then vacuum drying treatment is carried out at a temperature of 40℃ for 24h after stirring, to obtain a synthetic ester insulating oil.

[0074] Comparative Example 1

[0075] A synthetic ester insulating oil, the preparation method thereof comprising the steps of:

[0076] The product of Comparative Preparation Example 1 was added to MTE insulating oil, wherein the product of Comparative Preparation Example 1 accounted for 0.05wt% of the total insulating oil, and the mixed oil sample was dispersed and treated using a high-speed blender at a speed of 1200 rpm for 4 h, and after the end of stirring, vacuum drying treatment was performed at a temperature of 40°C for 24 h, to obtain a synthetic ester insulating oil.

[0077] Comparative Example 2

[0078] A synthetic ester insulating oil, the preparation method thereof comprising the steps of:

[0079] The product of Comparative Preparation Example 1 was added to MTE insulating oil, wherein the product of Comparative Preparation Example 1 accounted for 0.1wt% of the total insulating oil, and the mixed oil sample was dispersed and treated using a high-speed blender at a speed of 1200 rpm for 4 h, and after the end of stirring, vacuum drying treatment was performed at a temperature of 40°C for 24 h, to obtain a synthetic ester insulating oil.

[0080] Comparative Example 3

[0081] A synthetic ester insulating oil, the preparation method thereof comprising the steps of:

[0082] The product of Comparative Preparation Example 1 was added to MTE insulating oil, wherein the product of Comparative Preparation Example 1 accounted for 0.15wt% of the total insulating oil, and the mixed oil sample was dispersed and treated using a high-speed blender at a speed of 1200 rpm for 4 h, and after the end of stirring, vacuum drying treatment was performed at a temperature of 40°C for 24 h, to obtain a synthetic ester insulating oil.

[0083] Comparative Example 4

[0084] A synthetic ester insulating oil, the preparation method thereof comprising the steps of:

[0085] The product of Comparative Preparation Example 2 was added to MTE insulating oil, wherein the product of Comparative Preparation Example 2 accounted for 0.05wt% of the total insulating oil, and the mixed oil sample was dispersed and treated using a high-speed blender at a speed of 1200 rpm for 4 h, and after the end of stirring, vacuum drying treatment was performed at a temperature of 40°C for 24 h, to obtain a synthetic ester insulating oil.

[0086] Comparative Example 5

[0087] A synthetic ester insulating oil, the preparation method thereof comprising the steps of:

[0088] The product of Comparative Preparation Example 2 was added to MTE insulating oil, wherein the product of Comparative Preparation Example 2 was 0.1 wt% of the total insulating oil, and the mixed oil sample was dispersed and treated for 4 hours using a high-speed blender at a rotation speed of 1200 rpm, and after the end of the stirring, vacuum drying treatment was performed for 24 hours at a temperature of 40°C, to obtain a synthetic ester insulating oil.

[0089] Comparative Example 6

[0090] A synthetic ester insulating oil, the preparation method thereof comprising the steps of:

[0091] The product of Comparative Preparation Example 2 was added to MTE insulating oil, wherein the product of Comparative Preparation Example 2 was 0.15 wt% of the total insulating oil, and the mixed oil sample was dispersed and treated for 4 hours using a high-speed blender at a rotation speed of 1200 rpm, and after the end of the stirring, vacuum drying treatment was performed for 24 hours at a temperature of 40°C, to obtain a synthetic ester insulating oil.

[0092] Comparative Example 7

[0093] A synthetic ester insulating oil, the preparation method thereof comprising the steps of:

[0094] The product of Comparative Preparation Example 3 was added to MTE insulating oil, wherein the product of Comparative Preparation Example 3 was 0.05 wt% of the total insulating oil, and the mixed oil sample was dispersed and treated for 4 hours using a high-speed blender at a rotation speed of 1200 rpm, and after the end of the stirring, vacuum drying treatment was performed for 24 hours at a temperature of 40°C, to obtain a synthetic ester insulating oil.

[0095] Comparative Example 8

[0096] A synthetic ester insulating oil, the preparation method thereof comprising the steps of:

[0097] The product of Comparative Preparation Example 3 was added to MTE insulating oil, wherein the product of Comparative Preparation Example 3 was 0.1 wt% of the total insulating oil, and the mixed oil sample was dispersed and treated for 4 hours using a high-speed blender at a rotation speed of 1200 rpm, and after the end of the stirring, vacuum drying treatment was performed for 24 hours at a temperature of 40°C, to obtain a synthetic ester insulating oil.

[0098] Comparative Example 9

[0099] A synthetic ester insulating oil, the preparation method thereof comprising the steps of:

[0100] The product of Comparative Preparation Example 3 was added to MTE insulating oil, wherein the product of Comparative Preparation Example 3 was 0.15 wt% of the total insulating oil, and the mixed oil sample was dispersed and treated for 4 hours using a high-speed blender at a rotation speed of 1200 rpm, and after the end of the stirring, vacuum drying treatment was performed for 24 hours at a temperature of 40°C, to obtain a synthetic ester insulating oil.

[0101] Comparative Example 10

[0102] A synthetic ester insulating oil, the method for preparing the same comprising the steps of:

[0103] The product of Comparative Preparation Example 4 was added to MTE insulating oil, wherein the product of Comparative Preparation Example 4 accounted for 0.05wt% of the total insulating oil, the mixed oil sample was dispersed and treated using a high-speed blender at a rotational speed of 1200 rpm for 4 h, and after the end of stirring, vacuum drying treatment was performed at a temperature of 40°C for 24 h, to obtain a synthetic ester insulating oil.

[0104] Comparative Example 11

[0105] A synthetic ester insulating oil, the method for preparing the same comprising the steps of:

[0106] The product of Comparative Preparation Example 4 was added to MTE insulating oil, wherein the product of Comparative Preparation Example 4 accounted for 0.1wt% of the total insulating oil, the mixed oil sample was dispersed and treated using a high-speed blender at a rotational speed of 1200 rpm for 4 h, and after the end of stirring, vacuum drying treatment was performed at a temperature of 40°C for 24 h, to obtain a synthetic ester insulating oil.

[0107] Comparative Example 12

[0108] A synthetic ester insulating oil, the method for preparing the same comprising the steps of:

[0109] The product of Comparative Preparation Example 4 was added to MTE insulating oil, wherein the product of Comparative Preparation Example 4 accounted for 0.15wt% of the total insulating oil, the mixed oil sample was dispersed and treated using a high-speed blender at a rotational speed of 1200 rpm for 4 h, and after the end of stirring, vacuum drying treatment was performed at a temperature of 40°C for 24 h, to obtain a synthetic ester insulating oil.

[0110] Comparative Example 13

[0111] A mineral insulating oil, the method for preparing the same comprising the steps of:

[0112] The product of Preparation Example 1 was added to Karamay #25 mineral oil, wherein the product of Preparation Example 1 accounted for 0.05wt% of the total insulating oil, the mixed oil sample was dispersed and treated using a high-speed blender at a rotational speed of 1200 rpm for 4 h, and after the end of stirring, vacuum drying treatment was performed at a temperature of 40°C for 24 h, to obtain a mineral insulating oil.

[0113] Comparative Example 14

[0114] A mineral insulating oil, the method for preparing the same comprising the steps of:

[0115] The product of Preparation Example 1 was added to Karamay #25 mineral oil, with the product of Preparation Example 1 accounting for 0.1 wt% of the total insulating oil, and the mixed oil sample was dispersed and treated using a high-speed stirrer at a rotational speed of 1200 rpm for 4 h, and after the stirring was completed, vacuum drying treatment was performed at a temperature of 40°C for 24 h, to obtain a mineral insulating oil.

[0116] Comparative Example 15

[0117] A mineral insulating oil, the preparation method thereof comprising the following steps:

[0118] The product of Preparation Example 1 was added to Karamay #25 mineral oil, with the product of Preparation Example 1 accounting for 0.15 wt% of the total insulating oil, and the mixed oil sample was dispersed and treated using a high-speed stirrer at a rotational speed of 1200 rpm for 4 h, and after the stirring was completed, vacuum drying treatment was performed at a temperature of 40°C for 24 h, to obtain a mineral insulating oil.

[0119] Comparative Example 16

[0120] A synthetic ester insulating oil, the preparation method thereof comprising the following steps:

[0121] The activated tin oxide nanosieve of step (2) of Preparation Example 1 was added to MTE insulating oil, with the activated tin oxide nanosieve accounting for 0.05 wt% of the total insulating oil, and the mixed oil sample was dispersed and treated using a high-speed stirrer at a rotational speed of 1200 rpm for 4 h, and after the stirring was completed, vacuum drying treatment was performed at a temperature of 40°C for 24 h, to obtain a synthetic ester insulating oil.

[0122] Comparative Example 17

[0123] A synthetic ester insulating oil, the preparation method thereof comprising the following steps:

[0124] The activated tin oxide nanosieve of step (2) of Preparation Example 1 was added to MTE insulating oil, with the activated tin oxide nanosieve accounting for 0.1 wt% of the total insulating oil, and the mixed oil sample was dispersed and treated using a high-speed stirrer at a rotational speed of 1200 rpm for 4 h, and after the stirring was completed, vacuum drying treatment was performed at a temperature of 40°C for 24 h, to obtain a synthetic ester insulating oil.

[0125] Comparative Example 18

[0126] A synthetic ester insulating oil, the preparation method thereof comprising the following steps:

[0127] The activated tin oxide nanosieve prepared in step (2) of Preparation Example 1 was added to MTE insulating oil, and the activated tin oxide nanosieve accounted for 0.15wt% of the mass fraction of the whole insulating oil. The mixed oil sample was dispersed and treated by using a high-speed stirrer at a speed of 1200 rpm for 4 h, and then vacuum drying treatment was carried out at a temperature of 40°C for 24 h after stirring, to obtain synthetic ester insulating oil.

[0128] Comparative Example 19

[0129] A synthetic ester insulating oil, the preparation method comprising the following steps:

[0130] The MTE insulating oil was dispersed and treated by using a high-speed stirrer at a speed of 1200 rpm for 4 h, and then vacuum drying treatment was carried out at a temperature of 40°C for 24 h after stirring, to obtain synthetic ester insulating oil.

[0131] Comparative Example 20

[0132] A mineral insulating oil, the preparation method comprising the following steps:

[0133] The Karamay #25 mineral oil was dispersed and treated by using a high-speed stirrer at a speed of 1200 rpm for 4 h, and then vacuum drying treatment was carried out at a temperature of 40°C for 24 h after stirring, to obtain mineral insulating oil.

[0134] Performance detection test

[0135] 1. According to IEC 60897:1987 and DL / T 421-2009 standards, the insulating oils of the examples and comparative examples were subjected to impulse voltage test and volume resistivity measurement by using a CJ1326 type impulse voltage generator and an insulating oil volume resistivity tester, and the test results are shown in Table 1.

[0136] Table 1-Performance test results of the insulating oils of the examples and comparative examples of the present application

[0137]

[0138]

[0139] As shown in Table 1, the modified tin oxide nanosieve in Examples 1-3 was prepared by sol-gel method, and the modified tin oxide nanosieve in Comparative Examples 1-3 was prepared by hydrothermal method. It can be found that the impulse insulation strength improvement effect of synthetic ester insulating oil in Examples 1-3 is better than that in Comparative Examples 1-3, because the modified tin oxide nanosieve prepared by sol-gel method has more uniform pore size and more accurate pore size distribution, and has higher chemical purity and structural stability.

[0140] As shown in Table 1, the modified tin oxide nanosieves in Examples 1-3 were treated with silane coupling agent activation, and the modified tin oxide nanosieves in Comparative Examples 4-6 were not treated with activation, and the modified tin oxide nanosieves in Examples 1-3 had better effect on improving the impulse insulation strength of synthetic ester insulating oil. This is because the silane coupling agent can act as a molecular bridge between the nanosieve and linoleic acid, and improve the grafting rate of linoleic acid on the surface of the nanosieve. The linoleic acid modified nanosieve has a very high specific surface area and surface effect, and can be polarized under the action of an electric field to generate a large number of traps. The electric charge on the surface of the nanosieve can capture and neutralize free electrons in the insulating oil, thereby delaying the formation of discharge channels and improving the breakdown voltage of the synthetic ester insulating oil.

[0141] As shown in Table 1, the modified tin oxide nanosieves in Examples 1-3 were modified with linoleic acid on the surface, and the modified tin oxide nanosieves in Comparative Examples 7-9 were modified with oleic acid, and the modified tin oxide nanosieves in Examples 1-3 had better effect on improving the impulse insulation strength of synthetic ester insulating oil.

[0142] As shown in Table 1, the nanosieve of tin oxide in Comparative Examples 10-12 used a solid single crystal, and the specific surface was low, and the capture efficiency of free electrons in the synthetic ester insulating oil in the electric field was low, resulting in poor ability to improve the breakdown voltage of the synthetic ester insulating oil. The tin oxide nanosieve of Examples 1-3 had a porous structure and high surface energy, and could efficiently capture free electrons in the electric field, delay the formation of discharge channels, and effectively improve the breakdown voltage of the synthetic ester insulating oil.

[0143] As shown in Table 1, the nanosieves in Comparative Examples 16-18 were not modified with linoleic acid on the surface, resulting in low impulse insulation strength of the synthetic ester insulating oil. The nanosieve of Examples 1-3 was modified with linoleic acid on the surface, and the surface of the nanosieve had long-chain hydrocarbon groups of linoleic acid, which improved the lipophilicity and dispersibility of the nanosieve in organic solvents, and helped the nanosieve to disperse in the synthetic ester insulating oil, improve the capture efficiency of the nanosieve for electric charges, and improve the impulse insulation strength of the insulating oil.

[0144] As shown in Table 1, the amount of nanosieve added to the synthetic ester insulating oil in Examples 1-4 was gradually increased, and the optimal impulse insulation strength was obtained when the amount of nanosieve was 0.15wt%. With the continuous increase of the content of nanosieve, the impulse insulation strength of the insulating oil was reduced, indicating that too much nanosieve would increase the agglomeration phenomenon, reduce the contact area of the nanosieve with the insulating oil, and thus reduce the insulation performance.

[0145] The above specific embodiments further illustrate the purpose, technical solutions and advantages of the present application. It should be understood that the above description is only for specific embodiments of the present application and is not intended to limit the protection scope of the present application. It is particularly pointed out that any modification, equivalent replacement, improvement, etc. made by those skilled in the art within the spirit and principles of the present application shall be included in the protection scope of the present application.

Claims

1. The application of a modified tin oxide nanosieve grafted with linoleic acid in the preparation of synthetic ester insulating oil, characterized in that, The preparation method of the modified tin oxide nanosieve grafted with linoleic acid includes the following steps: (1) Disperse tin chloride in an ethanol aqueous solution, add alkali to adjust the pH value to trigger the hydrolysis reaction, and obtain a sol. Heat the sol in an oil bath at 40-50℃ and stir to react. After vacuum drying, calcine in an inert gas atmosphere, wash, vacuum dry, and sieve to obtain tin oxide nanosieves. (2) Disperse the silane coupling agent in solvent A to obtain a coupling agent solution. Coat the coupling agent solution evenly on the surface of the tin oxide nanosieve by spraying. Place it in a constant temperature and humidity environment of 70-90℃ and 50%-70% for constant temperature and humidity reaction. Wash and vacuum dry to obtain activated tin oxide nanosieve. (3) The activated tin oxide nanosieve and linoleic acid were mixed in solvent B, heated to 70-90℃ and stirred to react, centrifuged, the precipitate was washed and dried in a vacuum dryer to obtain the modified tin oxide nanosieve grafted with linoleic acid. In step (1), the size of the tin oxide nanosieve is 50-200 nm.

2. The application of the linoleic acid-grafted tin oxide nanosieve as described in claim 1 in the preparation of synthetic ester insulating oil, characterized in that, In step (1), the mass ratio of tin chloride to aqueous ethanol solution is 1:(4-6), and / or, alkali is added to adjust the pH value to 7.8-8.

2.

3. The application of the linoleic acid-grafted tin oxide nanosieve as described in claim 1 in the preparation of synthetic ester insulating oil, characterized in that, In step (1), the volume concentration of the ethanol aqueous solution is 50%-80%; And / or, in step (1), the base is sodium hydroxide; And / or, in step (1), the oil bath heating reaction time is 12-24 h; And / or, in step (1), the inert gas is argon; And / or, in step (1), the calcination temperature is 850-950℃ and the calcination time is 3-4 h; And / or, in step (1), the vacuum drying temperature is 30-50℃ and the time is 24-48 h.

4. The application of the linoleic acid-grafted tin oxide nanosieve as described in claim 1 in the preparation of synthetic ester insulating oil, characterized in that, In step (2), the concentration of silane coupling agent in the coupling agent solution is 1wt%-3wt%2%, and the mass ratio of the coupling agent solution for spraying to tin oxide nanosieve is 1:(2-4).

5. The application of the tin oxide nanosieve grafted with linoleic acid as described in claim 1 in the preparation of synthetic ester insulating oil, characterized in that, In step (2), solvent A is acetone; And / or, in step (2), the constant temperature and humidity reaction time is 20-28 h; And / or, in step (2), the washing solvent is ethanol; And / or, in step (2), the vacuum drying temperature is 30-50℃ and the time is 24-48 h.

6. The application of the linoleic acid-grafted tin oxide nanosieve as described in claim 1 in the preparation of synthetic ester insulating oil, characterized in that, In step (3), the mass ratio of the activated tin oxide nanosieve to linoleic acid is 1:(1-4). And / or, in step (3), the mass ratio of the activated tin oxide nanosieve to solvent B is 1:(4-6); And / or, in step (3), solvent B is n-hexane; And / or, in step (3), the stirring reaction time is 10-20 h; And / or, in step (3), the washing solvent is n-hexane; And / or, in step (3), the vacuum drying temperature is 30-50℃ and the time is 24-48 h.

7. A synthetic ester insulating oil, characterized in that, The invention includes 0.05wt%-0.2wt% of linoleic acid-grafted tin oxide nanosieves, wherein the linoleic acid-grafted tin oxide nanosieves are prepared by the preparation method of the modified linoleic acid-grafted tin oxide nanosieves according to any one of claims 1-6.

8. The synthetic ester insulating oil according to claim 7, characterized in that, It also includes additives at a mass fraction of 0-5 wt% and the balance of MTE insulating oil.

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