High-temperature-resistant heat-conducting oil and preparation method thereof

Abstract

The application belongs to the technical field of heat conducting oil, and specifically provides a high-temperature-resistant heat conducting oil and a preparation method thereof.The high-temperature-resistant heat conducting oil comprises a composite base oil, an antioxidant, a dispersant and a detergent, and the composite base oil is oligomeric siloxane stably dispersing nano boron nitride.The high-temperature-resistant heat conducting oil prepared by the application has the characteristics of high heat conduction, high flash point, high use temperature, low carbon residue, low corrosion and long-term stability.

Description

Technical Field

[0001] This application belongs to the field of heat transfer oil technology, and in particular relates to a high-temperature resistant heat transfer oil and its preparation method. Background Technology

[0002] Thermal oil is a heat transfer medium. Due to its characteristics such as uniform heating, accurate temperature control, ability to generate high temperature under low vapor pressure, good heat transfer effect, energy saving, and convenient transportation and operation, it has been widely used in various occasions in recent years.

[0003] As a highly efficient and safe heat transfer medium, the demand for heat transfer oil is constantly increasing. Emerging fields such as concentrated solar power generation, high-temperature processing of lithium battery materials, and semiconductor packaging are placing higher demands on the temperature resistance of heat transfer media, driving the continuous expansion of heat transfer oil applications in these fields. Currently, heat transfer oils are mainly divided into two types: mineral-based and synthetic. Mineral-based heat transfer oils have low operating temperatures, poor thermal stability, and can only be used below 300℃, with a relatively short service life. Synthetic heat transfer oils, including biphenyl-biphenyl ether, hydrogenated terphenyl, benzylcyclohexane, and alkylnaphthalene, have characteristics such as appropriate density, low viscosity, low energy consumption, good flow properties, good heat transfer performance, high thermal conductivity, good thermal stability, and long service life.

[0004] To further improve the high-temperature resistance of heat transfer oil, nano-thermal conductive particles are added to traditional heat transfer oil. This can increase the thermal conductivity of the heat transfer oil by 40%-60% compared to traditional products, better meeting the high requirements of emerging fields for the temperature resistance of heat transfer media. However, under high-temperature conditions, the nanoparticles in this type of heat transfer oil are prone to spontaneous aggregation, forming clumps or depositing on the surface of the heat transfer oil. This not only reduces the thermal conductivity of the heat transfer oil, but may also lead to system blockage or equipment damage. Summary of the Invention

[0005] To address the aforementioned issues and further improve the long-term high-temperature resistance of heat transfer oils, this application provides a high-temperature resistant heat transfer oil and its preparation method.

[0006] This application first provides a high-temperature resistant heat transfer oil, comprising the following components by weight: 80-90 parts of composite base oil, 0.5-1.5 parts of antioxidant, 1-3 parts of dispersant, and 2-3 parts of detergent; the composite base oil is prepared by the following method:

[0007] 1) Under nitrogen protection, the solvent and end-capping agent are mixed in an environment of 0-5℃ and stirred evenly. Then, the monomer mixture and deionized water are slowly added dropwise. The temperature is then raised to 25-30℃ and stirred for 3-4 hours. After separation and purification, oligomeric siloxanes are obtained with a number average molecular weight of 2400-3200 and an average degree of polymerization of 5.3-10.5.

[0008] 2) Disperse the boron nitride nanoparticles in a solvent, add sodium hydroxide and lithium chloride, perform hydrothermal treatment for 3-5 hours, and then separate and purify to obtain hydroxylated boron nitride nanoparticles;

[0009] 3) The hydroxylated boron nitride nanoparticles were dispersed in an ethanol solution of 3-mercaptopropyltriethoxysilane, stirred at 70℃-90℃ for 5-7 h, and then separated and purified to obtain modified boron nitride nanoparticles.

[0010] 4) Under nitrogen atmosphere, the modified boron nitride nanoparticles are ultrasonically dispersed into oligomeric siloxanes, then a photoinitiator is added, and the mixture is stirred under UV light for 2-4 hours. After purification, the composite base oil is obtained.

[0011] Furthermore, in 1), the monomer mixture is composed of di-n-octyl dichlorosilane, diallyl dichlorosilane, and diphenyl dichlorosilane, wherein the molar ratio of di-n-octyl dichlorosilane, diallyl dichlorosilane, and diphenyl dichlorosilane is (0.2-0.4):(0.03-0.08):(0.4-0.6).

[0012] Specifically, the chemical structure of the oligomeric siloxane in this application is as follows:

[0013] .

[0014] The oligomeric siloxane of this application is an oligomeric linear polysiloxane molecule formed by the coupling polymerization of dichlorosilane monomers. It has a number average molecular weight of 2400-3200 g / mol and an average degree of polymerization (DP) of 5.3-10.5, and has excellent heat resistance and high thermal conductivity.

[0015] Furthermore, in 1), the ratio of the total molar number of the capping agent to the monomer is 0.1-0.2.

[0016] Furthermore, in step 1), the amount of deionized water added is 1.1-1.2 times the total molar number of monomers.

[0017] Furthermore, in 1), the solvent is cyclohexane.

[0018] Furthermore, in 1), the capping agent is hexamethyldisiloxane.

[0019] Furthermore, in step 2), the mass ratio of nano boron nitride powder, sodium hydroxide, and lithium chloride is 1:(3-5):(25-50).

[0020] Furthermore, in step 2), the solvent is ethanol.

[0021] Furthermore, in step 2), the hydrothermal temperature is 140℃-160℃.

[0022] Furthermore, in step 3), the mass ratio of hydroxylated boron nanonitride to 3-mercaptopropyltrimethoxysilane is 1:(0.1-0.5).

[0023] Furthermore, in 3), the ethanol solution of 3-mercaptopropyltriethoxysilane contains 3-mercaptopropyltrimethoxysilane, deionized water and anhydrous ethanol; the mass ratio of 3-mercaptopropyltrimethoxysilane, deionized water and anhydrous ethanol is (0.1-0.5):(2.5-5):(12-18).

[0024] Furthermore, in step 4), the mass ratio of oligomeric siloxane to modified nano-boron nitride is (20-30):(0.5-1.5).

[0025] Furthermore, in 4), the mass of the photoinitiator is 0.1-1% of the mass of the oligomeric siloxane.

[0026] Furthermore, the antioxidant is a hindered phenolic antioxidant and a phosphite antioxidant.

[0027] Furthermore, the dispersant is one or more of polyisobutylene succinimide and polyisobutylene phosphate amine salt.

[0028] Furthermore, the detergent is high-alkalinity synthetic calcium sulfonate.

[0029] This application also provides a method for preparing a high-temperature heat transfer oil, comprising the following steps: weighing a composite base oil, an antioxidant, a detergent, and a dispersant in proportion; heating the composite base oil to 40-60°C, and adding the antioxidant, detergent, and dispersant in sequence while stirring, and mixing thoroughly to obtain the high-temperature heat transfer oil.

[0030] Compared with the prior art, this application has the following beneficial effects:

[0031] 1. This application uses a stable system of low-polysiloxane and modified nano boron nitride chemical dispersion as a composite base oil, and adds antioxidants, dispersants and detergents to prepare a high-temperature heat transfer oil. The prepared high-temperature heat transfer oil has the characteristics of high thermal conductivity, high flash point, high operating temperature, low residual carbon, low corrosion and long-term stability.

[0032] 2. This application first synthesizes low-polymer polysilanes using di-n-octyldichlorosilane, diallyldichlorosilane, and diphenyldichlorosilane as monomers. The n-octyl alkyl chain in this low-polymer polysilane provides the heat transfer oil with lower viscosity and stronger fluidity. The phenyl group enhances the main chain bond energy of the low-polymer polysilane, improving thermal conductivity and high-temperature stability, and avoiding the high-temperature gelation of traditional silicone oils. The introduced alkenyl group can undergo a click reaction with the mercaptosilane coupling agent-modified nano-boron nitride in a photoinitiator, allowing the nano-boron nitride to be stably dispersed in the heat transfer oil, further improving the thermal stability of the heat transfer oil at high temperatures, extending its thermal oxidation life, and enhancing its long-term stability at high temperatures. Attached Figure Description

[0033] Figure 1 The image shows the infrared characterization of the modified nano-boron nitride and composite base oil in Example 3 of this application.

[0034] Figure 2 The images show the dispersion stability of the composite base oil prepared from unmodified nano-boron nitride and oligomeric siloxane in Example 3 of this application, as well as the dispersion stability of the composite base oil prepared from modified nano-boron nitride and oligomeric siloxane. Detailed Implementation

[0035] The technical solutions in the embodiments of this application will be clearly and completely described below. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of this application.

[0036] 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 this application belongs. The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0037] When using “including,” “having,” and “contains” as described herein, the intention is to cover non-exclusive inclusion, unless an explicit qualifying term such as “only,” “consisting of,” etc., is used, in which case another component may be added.

[0038] The terms "preferred," "more preferably," "better," and "even better" used in this application refer to embodiments of this application that provide certain beneficial effects under certain circumstances. However, other embodiments may also be preferred under the same or other circumstances. Furthermore, the description of one or more preferred embodiments does not imply that other embodiments are unavailable, nor is it intended to exclude other embodiments from the scope of this application. That is, in this application, "preferred," "more preferably," "better," and "even better" are merely descriptions of implementations or embodiments with better effects, but do not constitute a limitation on the scope of protection of this application.

[0039] In this application, terms such as "further," "even more," and "particularly" are used for descriptive purposes and indicate differences in content, but should not be construed as limiting the scope of protection of this application.

[0040] In this application, "at least one" means one or more, such as one, two, or more. "Multiple" or "several" means at least two, such as two, three, etc., and "multi-layered" means at least two layers, such as two layers, three layers, etc., unless otherwise explicitly specified. In the description of this application, "several" means at least one, such as one, two, etc., unless otherwise explicitly specified.

[0041] When a numerical range is disclosed herein, the range is considered continuous and includes the minimum and maximum values ​​of the range, as well as every value between the minimum and maximum values. Furthermore, when the range refers to integers, it includes every integer between the minimum and maximum values ​​of the range. Additionally, when multiple ranges are provided to describe a feature or characteristic, the ranges may be combined. In other words, unless otherwise specified, all ranges disclosed herein should be understood to include any and all subranges to which they are incorporated.

[0042] Unless otherwise specified, all steps in this application may be performed sequentially or randomly. For example, the method comprising steps (a) and (b) indicates that the method may include steps (a) and (b) performed sequentially, or it may include steps (b) and (a) performed sequentially. For example, the mention that the method may also include step (c) indicates that step (c) may be added to the method in any order; for example, the method may include steps (a), (b), and (c), or it may include steps (a), (c), and (b), or it may include steps (c), (a), and (b), etc. Unless otherwise stated, singular terms may include plural forms and should not be construed as having a quantity of one.

[0043] In this application, "above" or "below" includes the number itself. For example, "below 1" includes 1.

[0044] To further improve the high-temperature resistance of heat transfer oils to meet the needs of emerging fields such as solar thermal power generation, high-temperature processing of lithium battery materials, and semiconductor packaging, this application, after extensive experimental research, provides a high-temperature heat transfer oil. First, a low-polymer polysilane is synthesized using di-n-octyl dichlorosilane, diallyl dichlorosilane, and diphenyl dichlorosilane as monomers. The n-octyl alkyl chain in this low-polymer polysilane provides the heat transfer oil with lower viscosity and stronger fluidity. The phenyl group, with its high bond energy, high inertness, and steric hindrance effect, enhances the main chain bond energy of the low-polymer polysilane, significantly inhibiting main chain breakage at high temperatures, reducing oxidation risk, enhancing thermal conductivity, and avoiding the high-temperature gelation of traditional silicone oils.

[0045] Building upon this foundation, to further enhance the high-temperature resistance of heat transfer oil, the addition of nano-boron nitride was considered. Nano-boron nitride, as a novel nano-thermal conductive filler, possesses ultra-high thermal stability, excellent chemical inertness, and a layered crystal structure. Besides improving the thermal conductivity stability of the heat transfer oil at high temperatures and preventing high-temperature coking, it can also form a nanoscale physical barrier to reduce the escape of volatile components from the heat transfer oil at high temperatures. Simultaneously, it inhibits oxygen and moisture contact, delaying oxidative degradation, and terminates the degradation chain reaction through free radical capture, thus extending the thermal oxidation life of the heat transfer oil.

[0046] However, the dispersibility of boron nanonitride in heat transfer oil is fundamental to achieving the aforementioned effects. Traditional methods generally involve surface modification of boron nanonitride, such as fatty acid modification, and ultrasonic dispersion combined with dispersant aids, to increase its dispersibility in heat transfer oil. However, these methods still result in gradual agglomeration of the heat transfer oil under prolonged high-temperature operation, leading to a gradual deterioration in its performance. In this application, by introducing alkenyl groups into oligomeric siloxanes and using a mercaptosilane coupling agent to modify the surface of boron nanonitride, and then using a photoinitiator to chemically link the modified boron nanonitride with the oligomeric siloxane through a mercapto-double bond click reaction, a stable and uniformly dispersed system is formed. This system, used in conjunction with oxidants, detergents, and dispersants, significantly improves the thermal conductivity and long-term stability of the high-temperature heat transfer oil.

[0047] In some embodiments of this application, the high-temperature heat transfer oil comprises the following raw materials by weight: 80-90 parts of composite base oil, 0.5-1.5 parts of antioxidant, 1-3 parts of dispersant, and 2-3 parts of detergent.

[0048] The composite base oil is prepared using the following method:

[0049] 1) Under nitrogen protection, the solvent and capping agent are mixed in an environment of 0-5℃ and stirred evenly. Then, the monomer mixture and deionized water are slowly added dropwise. The temperature is then raised to 25-30℃ and stirred for 3-4 hours. After separation and purification, oligomeric siloxanes are obtained.

[0050] 2) Disperse the boron nitride nanoparticles in a solvent, add sodium hydroxide and lithium chloride, perform hydrothermal treatment for 3-5 hours, and then separate and purify to obtain hydroxylated boron nitride nanoparticles;

[0051] 3) The hydroxylated boron nitride nanoparticles were dispersed in an ethanol solution of 3-mercaptopropyltriethoxysilane, stirred at 70℃-90℃ for 5-7 h, and then separated and purified to obtain modified boron nitride nanoparticles.

[0052] 4) Under nitrogen atmosphere, the modified boron nitride nanoparticles are ultrasonically dispersed into oligomeric siloxanes, then a photoinitiator is added, and the mixture is stirred under UV light for 2-4 hours. After purification, the composite base oil is obtained.

[0053] In some specific embodiments of this application, in step 1), the monomer mixture is a mixture of di-n-octyl dichlorosilane, diallyl dichlorosilane, and diphenyl dichlorosilane, wherein the molar ratio of di-n-octyl dichlorosilane, diallyl dichlorosilane, and diphenyl dichlorosilane is (0.2-0.4):(0.03-0.08):(0.4-0.6); typically, but not limitingly, for example, it can be 0.2:0.03:0.4, 0.3:0.05:0.5, or 0.4:0.08:0.6.

[0054] Specifically, the chemical structure of the oligomeric siloxane in this application is as follows:

[0055] .

[0056] The oligomeric siloxane of this application is a linear oligomeric polysiloxane molecule synthesized by coupling polymerization of dichlorosilane monomers, with a number-average molecular weight of 2400-3200 g / mol and an average degree of polymerization (DP) of 5.3-10.5. The specific synthesis sequence is as follows: First, cyclohexane and the end-capping agent hexamethyldisiloxane are mixed, and then the three monomers are added dropwise; second, the reaction is initiated at a lower temperature, and then the temperature is increased to continue polymerization in the presence of water, ultimately yielding the oligomeric siloxane. Furthermore, analysis of the structure of the oligomeric siloxane of this application shows that the introduction of phenyl groups can improve heat resistance, and the introduction of double bonds facilitates subsequent modification and grafting. Long-chain alkyl groups can improve the comprehensive properties of the base oil, such as thermal conductivity and viscosity, exhibiting excellent heat resistance and high thermal conductivity.

[0057] In some specific embodiments of this application, in step 1), the ratio of the total molar number of the capping agent to the monomer is 0.1-0.2; typically, but not limitingly, it can be 0.1, 0.12, 0.14, 0.16, 0.18, or 0.2.

[0058] In some specific embodiments of this application, in step 1), the amount of deionized water added is 1.1-1.2 times the total molar number of monomers; typically, but not limitingly, it can be 1.1, 1.12, 1.14, 1.16, 1.18, or 1.2.

[0059] In some specific embodiments of this application, in step 1), the solvent is cyclohexane.

[0060] In some specific embodiments of this application, in step 1), the capping agent is hexamethyldisiloxane.

[0061] In some specific embodiments of this application, in step 2), the mass ratio of nano boron nitride powder, sodium hydroxide and lithium chloride is 1:(3-5):(25-50); typically, but not limitingly, it can be 1:3:25, 1:4:28, or 1:5:50.

[0062] In some specific embodiments of this application, in step 2), the solvent is ethanol.

[0063] In some specific embodiments of this application, in step 2), the hydrothermal temperature is 140℃-160℃; typically, but not limitingly, it can be 140℃, 145℃, 150℃, 155℃, or 160℃.

[0064] In some specific embodiments of this application, in step 3), the mass ratio of hydroxylated nano-boron nitride to 3-mercaptopropyltrimethoxysilane is 1:(0.1-0.5); typically, but not limitingly, it can be 1:0.1, 1:0.2, 1:0.3, 1:0.4, or 1:0.5.

[0065] In some specific embodiments of this application, in step 3), the ethanol solution of 3-mercaptopropyltriethoxysilane contains 3-mercaptopropyltrimethoxysilane, deionized water, and anhydrous ethanol; the mass ratio of 3-mercaptopropyltrimethoxysilane, deionized water, and anhydrous ethanol is (0.1-0.5):(2.5-5):(12-18); typically, but not limitingly, for example, it can be 0.1:2.5:12, 0.2:3.5:15, or 0.5:5:18.

[0066] In some specific embodiments of this application, in step 4), the mass ratio of oligomeric siloxane to modified nano-boron nitride is (20-30):(0.5-1.5); typically, but not limitingly, it can be 20:0.5, 25:1, or 30:1.5.

[0067] In some specific embodiments of this application, in step 4), the mass of the photoinitiator is 0.1-1% of the mass of the oligomeric siloxane; typically, but not limitingly, it can be 0.1%, 0.5%, or 1%.

[0068] Furthermore, the antioxidant is a hindered phenolic antioxidant and a phosphite antioxidant; typically, but not limitingly, it can be pentaerythritol tetrakis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate], octadecyl β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionate, N,N'-bis[β-(3,5-di-tert-butyl-4-hydroxyphenyl)propionyl]hexamethylenediamine, 2,4-di(n-octylthiomethyl)-6-methylphenol, tris(2,4-di-tert-butylphenyl) phosphite, bis(2,4-di-tert-butylphenyl) pentaerythritol diphosphite, tris(nonylphenyl) phosphite, or bis(2,4-di-tert-butyl-6-methylphenyl) phosphite.

[0069] In some specific embodiments of this application, the dispersant is one or more of polyisobutylene succinimide and polyisobutylene phosphate amine salt.

[0070] In some specific embodiments of this application, the detergent is a high-alkalinity synthetic calcium sulfonate; typically, but not limitingly, it can be T106, T107, T115B, T109, T116, T112, T114, T122, T117, T120, T108, T119, T121, T111, or T123.

[0071] This application also provides a method for preparing a high-temperature heat transfer oil, comprising the following steps: weighing a composite base oil, an antioxidant, a detergent, and a dispersant in proportion; heating the composite base oil to 40-60°C, and adding the antioxidant, detergent, and dispersant in sequence while stirring, and mixing thoroughly to obtain the high-temperature heat transfer oil.

[0072] The present application will be further illustrated by the following examples, but these examples do not limit the scope of the present application.

[0073] When numerical ranges are given in the embodiments, it should be understood that, unless otherwise stated in this application, both endpoints of each numerical range and any value between the two endpoints may be selected. Unless otherwise defined, all technical and scientific terms used in this application have the same meaning as commonly understood by one of ordinary skill in the art. Where specific conditions are not specified in the embodiments, conventional conditions or conditions recommended by the manufacturer shall apply. All reagents or instruments whose manufacturers are not specified are conventional products that can be purchased commercially. In addition to the specific methods, equipment, and materials used in the embodiments, based on the knowledge of the prior art possessed by one of ordinary skill in the art and the description in this application, any prior art methods, equipment, and materials similar to or equivalent to those described, used, or made by the methods, equipment, and materials in the embodiments of this application may be used to implement this application.

[0074] Example 1

[0075] A high-temperature heat transfer oil comprises the following raw materials by weight: 80g of composite base oil, 0.5g of antioxidant, 1g of dispersant, and 2g of detergent.

[0076] In this embodiment, the antioxidant is composed of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.

[0077] In this embodiment, the dispersant is polyisobutylene succinimide.

[0078] In this embodiment, the detergent is high-alkalinity synthetic calcium sulfonate (T106).

[0079] In this embodiment, the composite base oil is prepared using the following method:

[0080] 1) Under nitrogen protection, 50 mL of cyclohexane and 0.06 mol of hexamethyldisiloxane, the end-capping agent, were mixed at 0 °C and stirred until homogeneous. Then, 12.5 mL of a monomer mixture (composed of 0.2 mol of di-n-octyldichlorosilane, 0.03 mol of diallyldichlorosilane, and 0.4 mol of diphenyldichlorosilane) and 12.5 mL of deionized water were slowly added dropwise. The temperature was then raised to 25 °C and stirred for 3 h. The mixture was separated, the organic phase was collected, washed with water until neutral, dried with anhydrous magnesium sulfate to remove water, and the solvent was removed by selective removal under reduced pressure to obtain oligomeric siloxane.

[0081] 2) Disperse 1g of nano boron nitride powder in 100mL of ethanol, add 3g of sodium hydroxide and 25g of lithium chloride, and perform hydrothermal treatment at 140℃ for 3h. Then filter, wash the filter cake with ethanol and water in turn, and then vacuum dry at 40℃ to obtain hydroxylated nano boron nitride.

[0082] 3) Under nitrogen protection, 1 g of hydroxylated boron nitride nanoparticles were ultrasonically dispersed into 14.6 g of an ethanol solution of 3-mercaptopropyltriethoxysilane (containing 0.1 g of 3-mercaptopropyltriethoxysilane, 2.5 g of water, and 12 g of anhydrous ethanol). The mixture was stirred at 7 °C for 5 h, then centrifuged to separate the precipitate. The precipitate was washed with ethanol and water in sequence, and then dried under vacuum at 40 °C to obtain modified boron nitride nanoparticles.

[0083] 4) Under nitrogen atmosphere, 0.5g of modified nano boron nitride was ultrasonically dispersed into 20g of oligomeric siloxane, and 0.02g of photoinitiator (Omnirad 1173D) was added. The mixture was stirred at 800r / min for 2h under a UV lamp (365nm). Then, the initiator was removed by vacuum rotary evaporation at 60℃. The mixture was filtered through a 0.45μm filter membrane to obtain the composite base oil.

[0084] Example 2

[0085] A high-temperature heat transfer oil comprises the following raw materials by weight: 85g of composite base oil, 1g of antioxidant, 2g of dispersant, and 2.5g of detergent.

[0086] In this embodiment, the antioxidant is composed of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.1.

[0087] In this embodiment, the dispersant is polyisobutylene succinimide.

[0088] In this embodiment, the detergent is high-alkalinity synthetic calcium sulfonate (T106).

[0089] In this embodiment, the composite base oil is prepared using the following method:

[0090] 1) Under nitrogen protection, 50 mL of cyclohexane and 0.13 mol of hexamethyldisiloxane, the end-capping agent, were mixed at 2 °C and stirred until homogeneous. Then, 18.5 mL of a monomer mixture (a mixture of 0.3 mol of di-n-octyl dichlorosilane, 0.05 mol of diallyl dichlorosilane, and 0.5 mol of diphenyl dichlorosilane) and 18.5 mL of deionized water were slowly added dropwise. The temperature was then raised to 28 °C and stirred for 3.5 h. The mixture was separated, the organic phase was collected, washed with water until neutral, dried with anhydrous magnesium sulfate to remove water, and the solvent was removed by selective removal under reduced pressure to obtain oligomeric siloxane.

[0091] 2) Disperse 1g of nano boron nitride powder in 100mL of ethanol, add 4g of sodium hydroxide and 35g of lithium chloride, hydrothermally treat at 150℃ for 4h, then filter, wash the filter cake with ethanol and water in turn, and then vacuum dry at 50℃ to obtain hydroxylated nano boron nitride.

[0092] 3) Under nitrogen protection, 1g of hydroxylated boron nitride nanoparticles were ultrasonically dispersed into 18.8g of an ethanol solution of 3-mercaptopropyltriethoxysilane (containing 0.3g of 3-mercaptopropyltriethoxysilane, 3.5g of water, and 15g of anhydrous ethanol). The mixture was stirred at 80℃ for 6h, then centrifuged to separate the precipitate. The precipitate was washed with ethanol and water in sequence, and then dried under vacuum at 50℃ to obtain modified boron nitride nanoparticles.

[0093] 4) Under nitrogen atmosphere, 1g of modified nano boron nitride was ultrasonically dispersed into 25g of oligomeric siloxane, and 0.125g of photoinitiator (Omnirad 1173D) was added. The mixture was stirred at 9000r / min for 3h under a UV lamp (365nm). The initiator was then removed by vacuum rotary evaporation at 70℃. The mixture was filtered through a 0.45μm filter membrane to obtain the composite base oil.

[0094] Example 3

[0095] A high-temperature heat transfer oil comprises the following raw materials by weight: 90g of composite base oil, 1.5g of antioxidant, 3g of dispersant, and 3g of detergent.

[0096] In this embodiment, the antioxidant is composed of antioxidant 1010 and antioxidant 168 in a mass ratio of 1:1.2.

[0097] In this embodiment, the dispersant is polyisobutylene succinimide.

[0098] In this embodiment, the detergent is high-alkalinity synthetic calcium sulfonate (T106).

[0099] In this embodiment, the composite base oil is prepared using the following method:

[0100] 1) Under nitrogen protection, 50 mL of cyclohexane and 0.22 mol of hexamethyldisiloxane, the end-capping agent, were mixed at 5 °C and stirred until homogeneous. Then, 23.5 mL of deionized water were slowly added dropwise to a monomer mixture (the monomer mixture was composed of 0.4 mol of di-n-octyl dichlorosilane, 0.08 mol of diallyl dichlorosilane, and 0.6 mol of diphenyl dichlorosilane). The temperature was then raised to 30 °C and stirred for 4 h. The mixture was separated, the organic phase was collected, washed with water until neutral, dried with anhydrous magnesium sulfate to remove water, and the solvent was removed by selective removal under reduced pressure to obtain oligomeric siloxane.

[0101] 2) Disperse 1g of nano boron nitride powder in 100mL of ethanol, add 5g of sodium hydroxide and 50g of lithium chloride, hydrothermally treat at 160℃ for 5h, then filter, wash the filter cake with ethanol and water in turn, and then vacuum dry at 60℃ to obtain hydroxylated nano boron nitride.

[0102] 3) Under nitrogen protection, 1g of hydroxylated boron nitride nanoparticles were ultrasonically dispersed into 23.5g of an ethanol solution of 3-mercaptopropyltriethoxysilane (containing 0.5g of 3-mercaptopropyltriethoxysilane, 5g of water, and 18g of anhydrous ethanol). The mixture was stirred at 90℃ for 7h, then centrifuged to separate the precipitate. The precipitate was washed with ethanol and water in sequence, and then dried under vacuum at 60℃ to obtain modified boron nitride nanoparticles.

[0103] 4) Under nitrogen atmosphere, 1.5g of modified nano boron nitride was ultrasonically dispersed into 30g of oligomeric siloxane, and 0.3g of photoinitiator (Omnirad 1173D) was added. The mixture was stirred at 1000r / min for 4h under a UV lamp (365nm). The initiator was then removed by vacuum rotary evaporation at 80℃. The mixture was filtered through a 0.45μm filter membrane to obtain the composite base oil.

[0104] A method for preparing a high-temperature resistant heat transfer oil includes the following steps:

[0105] (1) Weigh out the composite base oil, antioxidant, detergent and dispersant in proportion;

[0106] (2) Heat the composite base oil to 60°C, add antioxidant, detergent and dispersant in sequence while stirring, mix thoroughly and evenly, filter with a 0.45μm filter membrane to obtain high temperature heat transfer oil.

[0107] Control group 1

[0108] Similar to Example 1, except that the composite base oil in this control group was replaced with an equal mass of oligomeric siloxane.

[0109] Control group 2

[0110] Similar to Example 1, except that the composite base oil in this control group was replaced with 78g of oligomeric siloxane and 2g of modified nano boron nitride.

[0111] Performance testing

[0112] The high-temperature heat transfer oils prepared in Examples 1-3, Control Group 1, and Control Group 2 were subjected to the following performance tests according to the GB23971-2009 standard and method. The results are shown in Table 1:

[0113] Table 1. Performance Test Results

[0114]

[0115] As can be seen from Table 1, the high-temperature heat transfer oils prepared in Examples 1-3 of this application have the characteristics of high thermal conductivity, high flash point, high operating temperature, low residual carbon, low corrosion, and long-term stability.

[0116] Infrared characterization was performed on the modified nano-boron nitride and composite base oil of Example 3, and the results are as follows: Figure 1 As shown, Figure 1 The blue absorption curve (top) represents modified nano-boron nitride, and the red absorption curve (bottom) represents composite base oil. It can be seen that 2560 cm⁻¹... -1 The absorption peak intensity of the thiol group at the left and right positions weakens, while the intensity at 600 cm⁻¹ decreases. -1 The significantly enhanced SC absorption peaks at the left and right indicate the occurrence of a thiol-alkene click reaction. The core of this reaction is the hydrothiolation of the carbon-carbon double bond. Under photoinduction, a small amount of photoinitiator generates a thiol radical, which then adds to the carbon-carbon double bond, producing a carbon-centered radical intermediate. This intermediate then undergoes chain transfer to the second thiol molecule, resulting in a thiol-alkene addition product. Additionally, the 1350 cm⁻¹ peak shows... -1 and 2970cm -1 The absorption peaks at the left and right positions represent the characteristic peaks of BN.

[0117] The composite base oil prepared from unmodified nano-boron nitride and oligomeric siloxane in Example 3, as well as the composite base oil prepared from modified nano-boron nitride and oligomeric siloxane, were evaluated for dispersion stability by observing their appearance. The results are as follows: Figure 2 As shown, Figure 2 The image on the left shows the dispersion stability of the composite base oil prepared from modified nano-boron nitride and oligomeric siloxanes. Figure 2 The right image shows the dispersion stability of the composite base oil prepared by unmodified nano-boron nitride and oligomeric siloxane. It can be seen that unmodified nano-boron nitride is prone to agglomeration. In this application, nano-boron nitride and oligomeric siloxane are chemically coupled to improve the dispersion uniformity and stability of nano-boron nitride. The oil has better light transmittance and no suspension phenomenon.

[0118] Although this application has been described in detail with reference to the foregoing embodiments, those skilled in the art can still modify the technical solutions described in the foregoing embodiments or make equivalent substitutions for some of the technical features. Any modifications, equivalent substitutions, improvements, etc., made within the spirit and principles of this application should be included within the protection scope of this application.

Claims

1. A high-temperature resistant heat transfer oil, characterized by comprising: The raw material comprises the following components by weight fraction: 80-90 parts of composite base oil, 0.5-1.5 parts of antioxidant, 1-3 parts of dispersant, and 2-3 parts of detergent; the composite base oil is prepared by the following method: 1) under nitrogen protection, the solvent and capping agent are mixed and stirred uniformly at 0-5℃, then the monomer mixture and deionized water are slowly dropped, and then the temperature is raised to 25-30℃, and the stirring is continued for 3-4h, and then the low polymer siloxane is obtained by separation and purification, the number average molecular weight is 2400-3200, and the average polymerization degree is 5.3-10.5; 2) the nano boron nitride powder is dispersed in the solvent, sodium hydroxide and lithium chloride are added, and then hydrothermal treatment is carried out for 3-5h, and then the hydroxylated nano boron nitride is obtained by separation and purification; 3) the hydroxylated nano boron nitride is dispersed into the 3-mercaptopropyl triethoxysilane ethanol solution, and then stirring is carried out at 70-90℃ for 5-7h, and then the modified nano boron nitride is obtained by separation and purification; 4) under nitrogen, the modified nano boron nitride is ultrasonic dispersed into the low polymer siloxane, and then the photoinitiator is added, and then stirring is carried out under ultraviolet lamp for 2-4h, and then the composite base oil is obtained by purification; In the 1), the monomer mixture is composed of di-n-octyl dichlorosilane, diallyl dichlorosilane and diphenyl dichlorosilane, and the molar ratio of di-n-octyl dichlorosilane, diallyl dichlorosilane and diphenyl dichlorosilane is (0.2-0.4):(0.03-0.08):(0.4-0.6); In the 1), the total molar ratio of the capping agent to the monomer is 0.1-0.2; In the 1), the amount of deionized water is 1.1-1.2 times of the total molar number of the monomer; In the 1), the capping agent is hexamethyldisiloxane; In the 4), the mass ratio of the low polymer siloxane to the modified nano boron nitride is (20-30):(0.5-1.5).

2. The high-temperature resistant heat transfer oil according to claim 1, wherein In the 1), the solvent is cyclohexane.

3. The high-temperature resistant heat transfer oil according to claim 1, wherein In the 2), the mass ratio of the nano boron nitride powder, sodium hydroxide and lithium chloride is 1:(3-5):(25-50); And / or, in the 2), the solvent is ethanol; And / or, in the 2), the hydrothermal temperature is 140-160℃.

4. The high-temperature resistant heat transfer oil according to claim 1, wherein In the 3), the mass ratio of the hydroxylated nano boron nitride to 3-mercaptopropyl trimethoxysilane is 1:(0.1-0.5); And / or, in the 3), the 3-mercaptopropyl triethoxysilane ethanol solution contains 3-mercaptopropyl trimethoxysilane, deionized water and anhydrous ethanol, and the mass ratio of 3-mercaptopropyl trimethoxysilane, deionized water and anhydrous ethanol is (0.1-0.5):(2.5-5):(12-18).

5. The high-temperature resistant heat transfer oil according to claim 1, wherein In the 4), the mass of the photoinitiator is 0.1-1% of the mass of the low polymer siloxane.

6. The high-temperature resistant heat transfer oil according to claim 1, wherein The antioxidant is a hindered phenolic antioxidant and a phosphite antioxidant.

7. The high-temperature resistant heat transfer oil according to claim 1, wherein The dispersant is polyisobutylene succinimide.

8. The high-temperature resistant heat transfer oil according to claim 1, wherein The detergent is high-alkali-value synthetic calcium sulfonate.

9. A method of preparing the high-temperature resistant heat transfer oil according to any one of claims 1 to 8, characterized by, It comprises the following steps: proportionally weighing composite base oil, antioxidant, detergent and dispersant; heating the composite base oil to 40-60 DEG C, and then adding the antioxidant, the detergent and the dispersant in turn under stirring, and fully mixing them to obtain the high-temperature-resistant heat-conducting oil.

Images