Heat-resistant organic silicon diluent and preparation method thereof

Abstract

The invention relates to the technical field of lubricating oil, and provides a heat-resistant organic silicon diluent and a preparation method thereof. The graphene oxide grafted with the long alkyl chain provided by the invention has amphipathicity, an oleophylic group in the graphene oxide can be well combined with organic silicon lubricating oil, a hydrophilic group can be well adsorbed on the surface of the modified boron nitride nanosheet, the agglomeration among the modified boron nitride nanosheets is prevented, and the dilution and dispersion performance is excellent. Alkylaniline, monocyclic aromatic hydrocarbon, polyolefin and polycyclic aromatic hydrocarbon used in the diluent have good dilution and dispersion effects, and succinimides and long alkyl chain grafted graphene oxide-modified boron nitride nanosheets are added, so that the dilution and dispersion effects of the diluent are amplified and enhanced, and the dilution performance is greatly improved.

Description

Technical Field

[0001] The invention relates to the technical field of lubricating oils, and in particular to a heat-resistant organic silicon diluent and a preparation method thereof. Background Art

[0002] Lubricating oil is widely used in chemical, textile, machinery and other industries. Lubricating oil is mainly composed of two parts: base oil and additives. Base oil is the main component of lubricating oil, accounting for more than 85%. With the rapid development of science and technology, especially the rapid development of the automobile industry, and the strengthening of environmental protection and energy-saving requirements, although the total supply of lubricating oil has not increased significantly, the demand for high-grade lubricating oil is growing. Heat-resistant silicone lubricating oil has excellent heat resistance, electrical insulation, weather resistance, hydrophobicity, physiological inertness and small surface tension, as well as low viscosity-temperature coefficient and high compression resistance; in addition, silicone oil also has many special properties, such as anti-oxidation, high flash point, low volatility, no corrosion to metal, non-toxicity, etc.

[0003] The oxidation products of lubricating oil are an important component of sludge. As they stay in the lubricating oil for a longer time, they will aggregate and precipitate, eventually leading to an increase in oil viscosity, aggravating engine wear, causing filter blockage, and affecting engine use. Adding diluents can improve the above problems, but the performance of existing diluents is poor and cannot disperse sludge well. The performance and life of lubricating oil still need to be improved. Summary of the invention

[0004] The purpose of the present invention is to solve at least one of the technical problems existing in the prior art and to provide a heat-resistant silicone diluent and a preparation method thereof.

[0005] The technical solution of the present invention is as follows:

[0006] The present invention provides a heat-resistant silicone diluent, comprising the following raw materials in parts by weight:

[0007] 20-30 parts of succinimides, 15-25 parts of alkylanilines, 5-10 parts of monocyclic aromatic hydrocarbons, 1-9 parts of graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains, 1-7 parts of polyolefins, and 0.3-1.5 parts of polycyclic aromatic hydrocarbons.

[0008] Succinimides can improve the anti-wear and temperature resistance of silicone lubricants, have the advantages of good cleaning and dispersion, and have a solubilizing effect, promote the compatibility of other components in the diluent, and ensure the overall stability of the diluent. Boron nitride nanosheets are small in size and can migrate to the surface of the friction pair to form a friction protection film, which has excellent anti-wear and anti-friction properties and effectively improves the working performance of lubricants at high temperatures and high speeds; graphene oxide grafted with long alkyl chains has amphiphilicity, in which the lipophilic group can combine well with silicone lubricants, and the hydrophilic group can be well adsorbed on the surface of modified boron nitride nanosheets to prevent the agglomeration of modified boron nitride nanosheets, thus obtaining graphene oxide grafted with long alkyl chains-modified boron nitride nanosheets with excellent dilution and dispersion properties, which can disperse the oxidation products of lubricants and prevent aggregation, and have a very excellent dilution and dispersion effect on lubricants. Alkylanilines, monocyclic aromatic hydrocarbons, polyolefins, and polycyclic aromatic hydrocarbons have good dilution and dispersion effects. Together with succinimides and graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains, the dilution and dispersion effects of the diluents are amplified and enhanced, greatly improving the dilution performance.

[0009] As a preferred technical solution of the present invention, the succinimides include at least one of succinimide, boronated monosuccinimide, polyisobutylene succinimide, and phosphated polyisobutylene succinimide;

[0010] The monocyclic aromatic hydrocarbons include at least one of toluene, xylene, ethylbenzene, cumene, 2-methylethylbenzene, 3-methylethylbenzene, 4-methylethylbenzene, and dodecylbenzene;

[0011] The polycyclic aromatic hydrocarbons include naphthalene;

[0012] The alkylanilines include at least one of dialkyldiphenylamine, 4-dodecylaniline, 4-hexadecylaniline and 4-octadecylaniline.

[0013] As a preferred technical solution of the present invention, the long alkyl chain in the graphene oxide grafted with a long alkyl chain includes at least one of a n-dodecyl chain, a n-tetradecyl chain, a n-hexadecyl chain, and a n-octadecyl chain.

[0014] As a preferred technical solution of the present invention, the polyolefin includes at least one of polypropylene and polybutylene.

[0015] As a preferred technical solution of the present invention, the number average molecular weight of the polyolefin is 500-1200.

[0016] Another object of the present invention is to provide a method for preparing a heat-resistant silicone diluent, comprising the following steps:

[0017] S1, mixing graphite, potassium ferrate, an oxidation enhancer and an acid to obtain iron oxide intercalated graphite;

[0018] S2, dispersing boron nitride in a nano-silicon dioxide solution, adding hexamethyldisilazane and stirring for a period of time, removing the solvent by solid-liquid separation, and obtaining modified boron nitride after drying;

[0019] S3, dispersing the modified boron nitride and iron oxide intercalated graphite in water, then mixing with aliphatic amine solution, reacting by ultrasonication and stirring, and then removing the solvent by solid-liquid separation to obtain graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains;

[0020] S4. Mix the graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains, succinimides, and alkylanilines, heat to 110-130° C., then add monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, and polyolefins, mix, and cool to obtain a heat-resistant silicone diluent.

[0021] The present invention uses potassium ferrate as an oxidant, and cooperates with an oxidation enhancer and acid-treated graphite, so that expansion occurs between graphite layers, and the product iron oxide is intercalated and adsorbed in the graphite oxide to obtain iron oxide intercalated graphite; the boron nitride is modified to enhance its lipophilicity, thereby improving its anti-friction and anti-wear performance for lubricating oil; the iron oxide intercalated graphite and the modified boron nitride are treated with fatty amines, and long alkyl chains are grafted on the surface of graphene oxide to make the graphene oxide amphiphilic, and the graphene oxide interacts well with the lubricating oil through its lipophilicity, and enhances its interaction with the modified boron nitride through its hydrophilicity, so that the graphene oxide and the modified boron nitride interact closely, and finally improves its dilution and dispersion performance for the lubricating oil.

[0022] As a preferred technical solution of the present invention, in step S1:

[0023] The temperature of the mixed reaction is <20°C and the time is 1-2.5h;

[0024] The oxidation enhancer includes sodium nitrate;

[0025] The acid includes concentrated sulfuric acid.

[0026] As a preferred technical solution of the present invention, in step S2:

[0027] The concentration of the nano-silicon dioxide solution is 0.5-2wt%;

[0028] The mass of the hexamethyldisilazane is 1.5-2.5 times that of boron nitride;

[0029] The stirring period is specifically: stirring at 25-50° C. for 1-4 hours.

[0030] As a preferred technical solution of the present invention, in step S3:

[0031] The mass ratio of the modified boron nitride, iron oxide intercalated graphite, and fatty amine solution is 0.8-1.5:0.8-1.5:10-200;

[0032] The solvent of the fatty amine solution includes at least one of dimethyl sulfoxide, N-methylpyrrolidone, dimethyl diformamide, methanol, ethanol, ethylene glycol, propanol, propylene glycol, butanol, polyethylene glycol, and polyvinyl alcohol;

[0033] The ultrasonic power of the ultrasound is 1-2kw, the ultrasonic frequency is 20-50kHz, and the ultrasonic time is 1-6h;

[0034] The stirring speed is 500-1000 rpm, and the time is 2-8 hours.

[0035] As a preferred technical solution of the present invention, the temperature reduction in step S4 is to reduce the temperature to 50-100°C.

[0036] The beneficial effects that can be achieved by the present invention are:

[0037] The present invention utilizes succinimides to improve the anti-wear performance and temperature resistance of silicone lubricating oil, has the advantages of good clean dispersion, and has a solubilizing effect, promotes the compatibility of other components in the diluent, and ensures the overall stability of the diluent. Boron nitride nanosheets are small in size and can migrate to the surface of the friction pair to form a friction protection film, have excellent anti-wear performance, and effectively improve the working performance of lubricating oil at high temperature and high speed; graphene oxide grafted with long alkyl chains has amphiphilicity, wherein the lipophilic group can be well combined with silicone lubricating oil, and the hydrophilic group can be well adsorbed on the surface of the modified boron nitride nanosheet to prevent the agglomeration of the modified boron nitride nanosheets, thereby obtaining graphene oxide grafted with long alkyl chains-modified boron nitride nanosheets with excellent dilution and dispersion performance, which can disperse the oxidation products of lubricating oil and prevent aggregation, and has a very excellent dilution and dispersion effect on lubricating oil. Alkylanilines, monocyclic aromatic hydrocarbons, polyolefins, and polycyclic aromatic hydrocarbons have good dilution and dispersion effects. Together with succinimides and graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains, the dilution and dispersion effects of the diluents are amplified and enhanced, greatly improving the dilution performance.

[0038] The present invention uses potassium ferrate as an oxidant, and cooperates with an oxidation enhancer and acid-treated graphite, so that expansion occurs between graphite layers, and the product iron oxide is intercalated and adsorbed in the graphite oxide to obtain iron oxide intercalated graphite; boron nitride is modified to enhance lipophilicity, and improves the anti-friction and anti-wear performance of lubricating oil; fatty amines are used to treat iron oxide intercalated graphite and modified boron nitride, and long alkyl chains are grafted on the surface of graphene oxide to make graphene oxide amphiphilic, and the graphene oxide interacts well with the lubricating oil through its lipophilicity, and the interaction with the modified boron nitride is enhanced through its hydrophilicity, so that the graphene oxide and the modified boron nitride interact closely, and finally the dilution and dispersion performance of the lubricating oil is improved. The preparation method provided by the present invention has strong operability, excellent performance, and good application prospects. DETAILED DESCRIPTION

[0039] The technical scheme in the embodiments of the present invention is clearly and completely described below. Obviously, the described embodiments are exemplary and are only used to explain the present invention, and cannot be interpreted as limiting the present invention. If specific techniques or conditions are not specified in the embodiments, they are carried out according to the techniques or conditions described in the literature in this area or according to the product instructions. The reagents or instruments used are conventional products that can be obtained by commercial purchase if the manufacturer is not specified.

[0040] Example 1

[0041] A heat-resistant silicone diluent comprises the following raw materials in parts by weight:

[0042] 20 parts of succinimide, 25 parts of dinonyldiphenylamine, 5 parts of xylene, 1.5 parts of graphene oxide-modified boron nitride nanosheets grafted with n-dodecyl chains, 1 part of polypropylene with a number average molecular weight of 500, and 0.5 parts of naphthalene.

[0043] The preparation method of the heat-resistant silicone diluent comprises the following steps:

[0044] S1, 100g of flake graphite (carbon content ≥99.9%, average particle size 30 microns), 300g of potassium ferrate, 50g of sodium nitrate and 2300mL of concentrated sulfuric acid were mixed and reacted at <20°C for 2h to obtain iron oxide intercalated graphite;

[0045] S2, dispersing boron nitride in a 0.5wt% nano-silicon dioxide solution, adding hexamethyldisilazane (1.5 times the mass of boron nitride), stirring at 25°C for 4h, removing the solvent by solid-liquid separation, and obtaining modified boron nitride after drying;

[0046] S3, dispersing the modified boron nitride and iron oxide intercalated graphite in water, and then mixing with a fatty amine solution (the solvent is dimethyl sulfoxide), ultrasonically treating for 6 hours at an ultrasonic power of 1 kW and an ultrasonic frequency of 20 kHz, and then stirring and reacting for 8 hours at a speed of 500 rpm, wherein the mass ratio of the modified boron nitride, the iron oxide intercalated graphite, and the fatty amine solution is 1:1:200, and then removing the solvent by solid-liquid separation to obtain graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains;

[0047] S4. Mix the graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains, succinimides, and alkylanilines, heat to 110° C., then add monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, and polyolefins and mix for 30 minutes, cool to 50° C., and obtain a heat-resistant silicone diluent.

[0048] Example 2

[0049] A heat-resistant silicone diluent comprises the following raw materials in parts by weight:

[0050] 30 parts of boronated monosuccinimide, 15 parts of dimethyl diphenylamine, 10 parts of dodecylbenzene, 9 parts of graphene oxide-modified boron nitride nanosheets grafted with n-tetradecyl chains, 7 parts of polybutene with a number average molecular weight of 1200, and 1.5 parts of naphthalene.

[0051] The preparation method of the heat-resistant silicone diluent comprises the following steps:

[0052] S1, 100g of flake graphite (carbon content ≥99.9%, average particle size 50 microns), 300g of potassium ferrate, 50g of sodium nitrate and 2300mL of concentrated sulfuric acid were mixed and reacted at <10°C for 1.5h to obtain iron oxide intercalated graphite;

[0053] S2, dispersing boron nitride in a 2wt% nano-silicon dioxide solution, adding hexamethyldisilazane (2.5 times the mass of boron nitride), stirring at 50°C for 1h, removing the solvent by solid-liquid separation, and obtaining modified boron nitride after drying;

[0054] S3, dispersing the modified boron nitride and iron oxide intercalated graphite in water, and then mixing with a fatty amine solution (the solvent is methanol), ultrasonicating for 1.5 hours under the conditions of an ultrasonic power of 2 kW and an ultrasonic frequency of 50 kHz, and then stirring and reacting for 2 hours at a speed of 1000 rpm, wherein the mass ratio of the modified boron nitride, the iron oxide intercalated graphite, and the fatty amine solution is 8:15:50, and then removing the solvent by solid-liquid separation to obtain graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains;

[0055] S4. Graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains, succinimides, and alkylanilines are mixed, heated to 130° C., and then monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, and polyolefins are added and mixed for 30 minutes, and the temperature is reduced to 90° C. to obtain a heat-resistant silicone diluent.

[0056] Example 3

[0057] A heat-resistant silicone diluent comprises the following raw materials in parts by weight:

[0058] 22 parts of polyisobutylene succinimide, 18 parts of 4-dodecylaniline, 6 parts of 2-methylethylbenzene and 3-methylethylbenzene, 3 parts of graphene oxide-modified boron nitride nanosheets grafted with n-hexadecyl chains, 2 parts of polypropylene with a number average molecular weight of 600, and 0.7 parts of naphthalene.

[0059] A method for preparing a heat-resistant silicone diluent comprises the following steps:

[0060] S1, 100g of flake graphite (carbon content ≥99.9%, average particle size 30 microns), 300g of potassium ferrate, 50g of sodium nitrate and 2300mL of concentrated sulfuric acid were mixed and reacted at <20°C for 2h to obtain iron oxide intercalated graphite;

[0061] S2, dispersing boron nitride in a 1wt% nano-silicon dioxide solution, adding hexamethyldisilazane twice the mass of boron nitride, stirring at 35°C for 3h, removing the solvent by solid-liquid separation, and obtaining modified boron nitride after drying;

[0062] S3, dispersing the modified boron nitride and iron oxide intercalated graphite in water, and then mixing with a fatty amine solution (the solvent is ethanol), ultrasonicating for 4 hours under the conditions of an ultrasonic power of 1.5 kW and an ultrasonic frequency of 30 kHz, and then stirring and reacting for 6 hours at a speed of 600 rpm, wherein the mass ratio of the modified boron nitride, the iron oxide intercalated graphite, and the fatty amine solution is 15:8:150, and then removing the solvent by solid-liquid separation to obtain graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains;

[0063] S4. Mix the graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains, succinimides, and alkylanilines, heat to 120° C., then add monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, and polyolefins and mix for 30 minutes, cool to 80° C., and obtain a heat-resistant silicone diluent.

[0064] Example 4

[0065] A heat-resistant silicone diluent comprises the following raw materials in parts by weight:

[0066] 10 parts of succinimide, 18 parts of phosphated polyisobutylene succinimide, 12 parts of dioctyl diphenylamine, 10 parts of 4-hexadecyl aniline, 8 parts of dodecylbenzene, 7 parts of graphene oxide-modified boron nitride nanosheets grafted with n-octadecyl chains, 5 parts of polypropylene with a number average molecular weight of 1000, and 1.2 parts of naphthalene.

[0067] A method for preparing a heat-resistant silicone diluent comprises the following steps:

[0068] S1, 100g of flake graphite (carbon content ≥99.9%, average particle size 30 microns), 300g of potassium ferrate, 50g of sodium nitrate and 2300mL of concentrated sulfuric acid were mixed and reacted at <20°C for 2h to obtain iron oxide intercalated graphite;

[0069] S2, dispersing boron nitride in a 1.5wt% nano-silicon dioxide solution, adding hexamethyldisilazane (1.8 times the mass of boron nitride), stirring at 40°C for 2h, removing the solvent by solid-liquid separation, and obtaining modified boron nitride after drying;

[0070] S3, dispersing the modified boron nitride and iron oxide intercalated graphite in water, and then mixing with a fatty amine solution (solvent is polyvinyl alcohol), ultrasonically treating for 2 hours at an ultrasonic power of 1.2 kW and an ultrasonic frequency of 40 kHz, and then stirring and reacting for 3 hours at a speed of 800 rpm, wherein the mass ratio of the modified boron nitride, iron oxide intercalated graphite, and fatty amine solution is 5:6:400, and then removing the solvent by solid-liquid separation to obtain graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains;

[0071] S4. Graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains, succinimides, and alkylanilines are mixed, heated to 115° C., and then monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, and polyolefins are added and mixed for 30 minutes, and the temperature is reduced to 70° C. to obtain a heat-resistant silicone diluent.

[0072] Example 5

[0073] A heat-resistant silicone diluent comprises the following raw materials in parts by weight:

[0074] 10 parts of boronated monosuccinimide, 15 parts of polyisobutylene succinimide, 10 parts of dimethyl diphenylamine, 10 parts of 4-dodecylaniline, 7.5 parts of xylene, 5 parts of graphene oxide-modified boron nitride nanosheets grafted with n-dodecyl chains, 4 parts of polybutene with a number average molecular weight of 800, and 1 part of naphthalene.

[0075] A method for preparing a heat-resistant silicone diluent comprises the following steps:

[0076] S1, 100g of flake graphite (carbon content ≥99.9%, average particle size 30 microns), 300g of potassium ferrate, 50g of sodium nitrate and 2300mL of concentrated sulfuric acid were mixed and reacted at <20°C for 2h to obtain iron oxide intercalated graphite;

[0077] S2, dispersing boron nitride in a 1.2wt% nano-silicon dioxide solution, adding hexamethyldisilazane twice the mass of boron nitride, stirring at 40°C for 2h, removing the solvent by solid-liquid separation, and obtaining modified boron nitride after drying;

[0078] S3, dispersing the modified boron nitride and iron oxide intercalated graphite in water, and then mixing with a fatty amine solution (the solvent is ethylene glycol and polyethylene glycol in a volume ratio of 1:1), ultrasonically treating for 3 hours at an ultrasonic power of 1.5 kW and an ultrasonic frequency of 30 kHz, and then stirring and reacting for 5 hours at a speed of 700 rpm, wherein the mass ratio of the modified boron nitride, the iron oxide intercalated graphite, and the fatty amine solution is 1:1:100, and then removing the solvent by solid-liquid separation to obtain graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains;

[0079] S4. Mix the graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains, succinimides, and alkylanilines, heat to 120° C., then add monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, and polyolefins, mix and cool to 60° C. to obtain a heat-resistant silicone diluent.

[0080] Comparative Example 1

[0081] Step S2 is removed, and step S3 directly uses boron nitride to react with iron oxide intercalated graphite and fatty amine solution. The rest is the same as Example 5.

[0082] Comparative Example 2

[0083] Step S3 is removed, and step S4 directly uses iron oxide intercalated graphite and modified boron nitride to react, and the rest is the same as Example 5.

[0084] Comparative Example 3

[0085] Step S1 is removed, and step S3 directly uses flake graphite to react with modified boron nitride and fatty amine solution. The rest is the same as Example 5.

[0086] Comparative Example 4

[0087] The graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains were removed, and the rest was the same as in Example 5.

[0088] The organic silicon diluent obtained in Examples 1-5 and Comparative Examples 1-4 was added to the organic silicon lubricating oil, and the added amount was 5wt% of the lubricating oil. The friction coefficient of the obtained lubricating oil was measured respectively. The dispersion of the lubricating oil was observed after standing at 25°C for 90 days. The results are shown in Table 1.

[0089] Table 1

[0090]

[0091] As can be seen from the data in Table 1, the diluent provided by the present invention has good dilution and dispersion effect and anti-friction effect, and has stable performance. Boron nitride modification, aliphatic amine solution grafting treatment, graphite oxidation intercalation treatment, and graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains will all affect the performance of the resulting diluent, especially aliphatic amine solution grafting treatment, graphite oxidation intercalation treatment, and graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains, indicating that the morphology and hydrophilicity of graphite will affect the performance of graphene, and the addition of graphene oxide-modified boron nitride nanosheets without grafting long alkyl chains greatly reduces the anti-friction effect of the diluent.

[0092] Finally, it should be noted that the above is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, it is still possible for those skilled in the art to modify the technical solutions described in the aforementioned embodiments or to make equivalent substitutions for some of the technical features therein. Any modifications, equivalent substitutions, improvements, etc. made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. A heat-resistant silicone diluent, characterized in that: The invention comprises the following raw materials in parts by weight: 20-30 parts of succinimides, 15-25 parts of alkylanilines, 5-10 parts of monocyclic aromatic hydrocarbons, 1-9 parts of graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains, 1-7 parts of polyolefins, and 0.3-1.5 parts of polycyclic aromatic hydrocarbons.

2. A heat-resistant silicone diluent according to claim 1, characterized in that: The succinimides include at least one of succinimide, boronized monosuccinimide, polyisobutylene succinimide, and phosphated polyisobutylene succinimide; The monocyclic aromatic hydrocarbons include at least one of toluene, xylene, ethylbenzene, cumene, 2-methylethylbenzene, 3-methylethylbenzene, 4-methylethylbenzene, and dodecylbenzene; The polycyclic aromatic hydrocarbons include naphthalene; The alkylanilines include at least one of dialkyldiphenylamine, 4-dodecylaniline, 4-hexadecylaniline and 4-octadecylaniline.

3. A heat-resistant silicone diluent according to claim 1, characterized in that: The long alkyl chain in the graphene oxide grafted with a long alkyl chain includes at least one of a n-dodecyl chain, a n-tetradecyl chain, a n-hexadecyl chain, and a n-octadecyl chain.

4. A heat-resistant silicone diluent according to claim 1, characterized in that: The polyolefin includes at least one of polypropylene and polybutylene.

5. The heat-resistant silicone diluent according to claim 1, characterized in that: The number average molecular weight of the polyolefin is 500-1200.

6. A method for preparing a heat-resistant silicone diluent, characterized in that: The following steps are involved: S1, mixing graphite, potassium ferrate, an oxidation enhancer and an acid to obtain iron oxide intercalated graphite; S2, dispersing boron nitride in a nano-silicon dioxide solution, adding hexamethyldisilazane and stirring for a period of time, removing the solvent by solid-liquid separation, and obtaining modified boron nitride after drying; S3, dispersing the modified boron nitride and iron oxide intercalated graphite in water, then mixing with aliphatic amine solution, reacting by ultrasonication and stirring, and then removing the solvent by solid-liquid separation to obtain graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains; S4. Mix the graphene oxide-modified boron nitride nanosheets grafted with long alkyl chains, succinimides, and alkylanilines, heat to 110-130° C., then add monocyclic aromatic hydrocarbons, polycyclic aromatic hydrocarbons, and polyolefins, mix, and cool to obtain a heat-resistant silicone diluent.

7. The method for preparing a heat-resistant silicone diluent according to claim 1, characterized in that: In step S1: The temperature of the mixed reaction is <20°C and the time is 1-2.5h; The oxidation enhancer includes sodium nitrate; The acid includes concentrated sulfuric acid.

8. The method for preparing a heat-resistant silicone diluent according to claim 1, characterized in that: In step S2: The concentration of the nano-silicon dioxide solution is 0.5-2wt%; The mass of the hexamethyldisilazane is 1.5-2.5 times that of boron nitride; The stirring period is specifically: stirring at 25-50° C. for 1-4 hours.

9. The method for preparing a heat-resistant silicone diluent according to claim 1, characterized in that: In step S3: The mass ratio of the modified boron nitride, iron oxide intercalated graphite, and fatty amine solution is 0.8-1.5:0.8-1.5:10-200; The solvent of the fatty amine solution includes at least one of dimethyl sulfoxide, N-methylpyrrolidone, dimethyl diformamide, methanol, ethanol, ethylene glycol, propanol, propylene glycol, butanol, polyethylene glycol, and polyvinyl alcohol; The ultrasonic power of the ultrasound is 1-2kw, the ultrasonic frequency is 20-50kHz, and the ultrasonic time is 1-6h; The stirring speed is 500-1000 rpm, and the time is 2-8 hours.

10. The method for preparing a heat-resistant silicone diluent according to claim 1, characterized in that: The temperature in step S4 is lowered to 50-100°C.

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