CN116254000A

CN116254000A - Heat-conducting silicone grease, preparation method and application thereof

Info

Publication number: CN116254000A
Application number: CN202310533399.9A
Authority: CN
Inventors: 罗祥华; 于晶晶
Original assignee: Contemporary Amperex Technology Co Ltd
Current assignee: Contemporary Amperex Technology Co Ltd
Priority date: 2023-05-12
Filing date: 2023-05-12
Publication date: 2023-06-13

Abstract

The embodiment of the application discloses a heat conduction silicone grease, a preparation method and application of the heat conduction silicone grease, wherein the heat conduction silicone grease comprises silicone oil, heat conduction filler and fluorine-containing silane coupling agent.

Description

Heat-conducting silicone grease, preparation method and application thereof

Technical Field

The application relates to the technical field of thermal interface materials, in particular to heat conduction silicone grease, a preparation method of the heat conduction silicone grease and application of the heat conduction silicone grease.

Background

Currently, electronic devices are rapidly developing in the directions of high performance, densification, high precision and high power, resulting in a great increase in the heat productivity of the electronic devices. At the same time, miniaturization of electronic devices has led to dramatic reductions in their heat dissipation space, resulting in heat accumulation. If heat cannot be dissipated in time, the stability and reliability of the heat dissipation device are seriously affected. To solve this problem, various thermal interface materials have been developed, such as thermally conductive gels, thermally conductive gaskets, and the like.

Disclosure of Invention

The present application has been made in view of the above problems, and an object thereof is to provide a heat conductive silicone grease, a method for producing the heat conductive silicone grease, and use thereof, for improving the performance of the heat conductive silicone grease.

In a first aspect, there is provided a thermally conductive silicone grease comprising: silicone oil, heat conducting filler and fluorine-containing silane coupling agent.

The fluorine-containing silane coupling agent can form hydroxyl through hydrolysis and chemical reaction with the heat-conducting filler, and has good compatibility with silicone oil, so that the fluorine-containing silane coupling agent can be used as a bridge for connecting the heat-conducting filler and the silicone oil to form a compact heat-conducting network, and the structural stability of the heat-conducting silicone grease can be cooperatively improved, so that the characteristics of low oil separation degree and high reliability can be shown; in addition, the electronegativity of fluorine atoms is highest in elements, so that fluorocarbon bond electron clouds are mostly gathered at one end of the fluorine atoms, the polarizability is reduced, the electron distribution is more uniform, the free volume can be increased by introducing the fluorine atoms, the number of polarized groups in unit volume is reduced, and therefore, the heat conduction silicone grease can show lower dielectric constant; in addition, because of the existence of fluorine atoms, the polarity of the fluorocarbon bonds is small, and the intermolecular acting force of the compound containing the fluorocarbon bonds is low, so that the surface energy is low, the self-lubricating property is realized, the self-lubricating effect can effectively inhibit the aggregation of the heat conducting filler, the uneven heat conduction of the heat conducting silicone grease is prevented, the promotion of the compatibility between the heat conducting filler is facilitated, a good heat conducting network is formed, and the good heat conducting property is shown. In summary, the heat-conducting silicone grease of the embodiment of the application can have excellent heat-conducting performance, low dielectric constant and high reliability.

With reference to the first aspect, in a possible implementation manner of the first aspect, the content of the fluorine-containing silane coupling agent is 0.1 to 2 parts by weight based on 100 parts by weight of the heat-conducting silicone grease; alternatively, the content of the fluorine-containing silane coupling agent is 0.5 to 2 parts by weight.

Based on the embodiment, the fluorine-containing silane coupling agent in the heat-conducting silicone grease can achieve better coupling, and is favorable for improving the compatibility between the heat-conducting fillers to form a good heat-conducting network, so that good heat-conducting performance can be shown.

In one possible implementation, the fluorine-containing silane coupling agent includes one or more of perfluorodecyl triethoxysilane, perfluorooctyl triethoxysilane, trifluoropropane trimethoxysilane, nonafluorohexyl trimethoxysilane; alternatively, the fluorine-containing silane coupling agent includes perfluorodecyl triethoxysilane.

Further, the fluorine-containing silane coupling agent may include one or more of perfluorodecyl triethoxysilane, perfluorooctyl triethoxysilane, trifluoropropane trimethoxysilane, and nonafluorohexyl trimethoxysilane having a purity of 96% or more.

Further, the fluorine-containing silane coupling agent may include one or more of perfluorodecyl triethoxysilane, perfluorooctyl triethoxysilane, trifluoropropane trimethoxysilane, and nonafluorohexyl trimethoxysilane having a purity of 98% or more.

With reference to the first aspect, in a possible implementation manner of the first aspect, the silicone oil is contained in an amount of 5 to 35 parts by weight based on 100 parts by weight of the heat-conducting silicone grease; alternatively, the silicone oil is present in an amount of 5 to 25 parts by weight.

With reference to the first aspect, in a possible implementation manner of the first aspect, the silicone oil includes one or more of methyl silicone oil, benzyl silicone oil, vinyl silicone oil, hydrogen-containing silicone oil, amino silicone oil, hydroxyl silicone oil and fluorine-containing silicone oil; optionally, the silicone oil includes one or more of methyl silicone oil, vinyl silicone oil, hydrogen-containing silicone oil, amino silicone oil, and hydroxyl silicone oil.

Specifically, when the silicone oil includes a fluorine-containing silicone oil, the content of fluorine atoms increases, so that the dielectric constant of the heat conductive silicone grease can be further reduced; and the self-lubricating effect brought by fluorine elements can further inhibit uneven heat conduction of the heat conduction silicone grease brought by agglomeration of the heat conduction filler, thereby improving the heat conduction performance of the heat conduction silicone grease.

With reference to the first aspect, in a possible implementation manner of the first aspect, the content of the heat conductive filler is 64-94 parts by weight based on 100 parts by weight of the heat conductive silicone grease; optionally, the content of the heat conductive filler is 85 to 94 parts by weight.

Based on the above embodiment, the heat conductive filler in the heat conductive silicone grease is in the range, which is favorable for forming a compact heat conductive network, and can improve the structural stability of the heat conductive silicone grease, thereby being capable of showing the characteristics of low oil separation degree and high reliability.

With reference to the first aspect, in a possible implementation manner of the first aspect, the thermally conductive filler includes an inorganic filler, and optionally, the inorganic filler includes one or more of a metal oxide, a metal nitride, a silicon oxide, a silicon carbide, a silicon nitride, a boron oxide, a boron carbide, and a boron nitride; optionally, the inorganic filler comprises one or more of aluminum oxide, zinc oxide, magnesium oxide, aluminum nitride, boron nitride, silicon dioxide.

The heat conduction filler of the embodiment of the application increases a heat conduction transmission path and accelerates heat transfer, so that the heat conduction coefficient of the heat conduction silicone grease is further increased, and the heat conduction performance is improved.

With reference to the first aspect, in a possible implementation manner of the first aspect, the particle size of the heat conductive filler ranges from 0.1 μm to 50 μm; optionally, the thermally conductive filler has a particle size in the range of 0.5 to 40 μm.

The particle size of the heat-conducting filler is in the range, so that the heat-conducting filler is uniformly dispersed in the heat-conducting silicone grease, agglomeration among particles can be reduced, a compact heat-conducting network is formed, the heat-conducting property and structural stability of the heat-conducting silicone grease are improved, the oil separation degree is reduced, and the reliability is improved.

In a second aspect, a method for preparing a thermally conductive silicone grease is provided, the method comprising: cleaning and drying the heat-conducting filler to obtain a pretreated filler; dispersing the fluorine-containing silane coupling agent and the pretreated filler to obtain modified filler; mixing the modified filler with silicone oil, and grinding to obtain semi-finished silicone grease; stirring the semi-finished silicone grease to obtain the heat-conducting silicone grease.

Based on the above embodiment, the heat conductive filler is subjected to the cleaning treatment and the drying treatment, and impurities and moisture contained on the surface of the heat conductive filler can be removed, thereby being beneficial to preventing the structural stability of the heat conductive silicone grease from being reduced due to the influence of the impurities or the moisture on the reaction between the fluorine-containing silane coupling agent and the heat conductive filler.

With reference to the second aspect, in a possible implementation manner of the second aspect, the cleaning treatment includes ultrasonic dispersion; and/or the drying treatment comprises vacuum drying.

With reference to the second aspect, in a possible implementation manner of the second aspect, the duration of the ultrasonic dispersion is 5-12 hours, and/or the temperature of the vacuum drying is 60-80 ℃.

With reference to the second aspect, in a possible implementation manner of the second aspect, the dispersing processing includes: stirring the fluorine-containing silane coupling agent and the pretreatment filler at a first rotating speed to obtain a pre-dispersed filler; stirring the pre-dispersed filler at a second rotating speed, and performing ultrasonic collaborative dispersion to obtain the modified filler, wherein the first rotating speed is smaller than the second rotating speed.

Based on the above embodiment, before stirring, because the granularity of the heat conducting filler is not uniform, and part of the agglomerated heat conducting filler exists, at this time, the agglomerated heat conducting filler cannot be directly stirred at a high speed to disperse so as to influence the heat conducting property and reliability of the heat conducting silicone grease, so that the heat conducting filler and the fluorine-containing silane coupling agent can be fully contacted and simultaneously are closely arranged through pre-dispersing and subsequent high-speed stirring and collaborative dispersing of an ultrasonic machine, a good heat conducting network is formed, and the heat conducting property and the structural stability of the heat conducting silicone grease are improved.

With reference to the second aspect, in a possible implementation manner of the second aspect, the first rotation speed is 20-650rpm/min, and/or the second rotation speed is 500-1300 rpm/min; and/or the frequency of the ultrasound is 20-55kHz.

With reference to the second aspect, in a possible implementation manner of the second aspect, the duration of stirring at the first rotational speed is 5-30min; and/or stirring at the second rotation speed for 10-30min.

With reference to the second aspect, in a possible implementation manner of the second aspect, the grinding treatment includes: and (3) grinding the modified filler and the silicone oil to be free of particles through a three-roller grinder to obtain semi-finished silicone grease.

Based on the above embodiments, densification and de-bubbling effects of the material can be achieved by the grinding process.

With reference to the second aspect, in a possible implementation manner of the second aspect, the stirring treatment includes vacuumizing at a temperature of 80-200 ℃, and stirring to obtain the heat-conducting silicone grease.

In a third aspect, there is provided a use of the thermally conductive silicone grease of any one of the first aspects or the thermally conductive silicone grease prepared according to the preparation method of any one of the second aspects in an electronic device.

Drawings

Fig. 1 is a schematic diagram of a preparation method of a heat-conducting silicone grease according to an embodiment of the present application.

Fig. 2 is a schematic diagram of the reliability test results of the heat conductive silicone grease of example 1 of the present application.

Fig. 3 is a schematic diagram of the results of the reliability test of the heat conductive silicone grease of comparative example 2 of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be described below with reference to the accompanying drawings.

Embodiments of the thermally conductive silica gel and the method of preparing the same according to the examples of the present application are specifically disclosed below. However, unnecessary detailed description may be omitted. For example, detailed descriptions of well-known matters and repeated descriptions of the actual same structure may be omitted. This is to avoid that the following description becomes unnecessarily lengthy, facilitating the understanding of those skilled in the art.

In the description of the present application, it is to be noted that, unless otherwise indicated, the meaning of "plurality" is two or more; the terms "upper," "lower," "left," "right," "inner," "outer," and the like indicate an orientation or positional relationship merely for convenience of description and to simplify the description, and do not indicate or imply that the devices or elements being referred to must have a particular orientation, be constructed and operated in a particular orientation, and thus are not to be construed as limiting the present application. Furthermore, the terms "first," "second," "third," and the like are used for descriptive purposes only and are not to be construed as indicating or implying relative importance.

The "range" disclosed herein is defined in terms of lower and upper limits, with a given range being defined by the selection of a lower and an upper limit, the selected lower and upper limits defining the boundaries of the particular range. Ranges that are defined in this way can be inclusive or exclusive of the endpoints, and any combination can be made, i.e., any lower limit can be combined with any upper limit to form a range. For example, if ranges of 60-120 and 80-110 are listed for a particular parameter, it is understood that ranges of 60-110 and 80-120 are also contemplated. Furthermore, if the minimum range values 1 and 2 are listed, and if the maximum range values 3,4 and 5 are listed, the following ranges are all contemplated: 1-3, 1-4, 1-5, 2-3, 2-4 and 2-5. In this application, unless otherwise indicated, the numerical range "a-b" represents a shorthand representation of any combination of real numbers between a and b, where a and b are both real numbers. For example, the numerical range "0-5" means that all real numbers between "0-5" have been listed throughout, and "0-5" is simply a shorthand representation of a combination of these values. When a certain parameter is expressed as an integer of 2 or more, it is disclosed that the parameter is, for example, an integer of 2, 3,4, 5, 6, 7, 8, 9, 10, 11, 12 or the like.

All steps of the present application may be performed sequentially or randomly, preferably sequentially, unless otherwise indicated. For example, the method comprises steps (a) and (b), meaning that the method may comprise steps (a) and (b) performed sequentially, or may comprise steps (b) and (a) performed sequentially. For example, the method may further include step (c), which means that step (c) may be added to the method in any order, for example, the method may include steps (a), (b) and (c), may include steps (a), (c) and (b), may include steps (c), (a) and (b), and the like.

Reference herein to "comprising" and "including" means open ended, as well as closed ended, unless otherwise noted. For example, the terms "comprising" and "comprises" may mean that other components not listed may be included or included, or that only listed components may be included or included.

The term "or" is inclusive in this application, unless otherwise specified. For example, the phrase "a or B" means "a, B, or both a and B. More specifically, either of the following conditions satisfies the condition "a or B": a is true (or present) and B is false (or absent); a is false (or absent) and B is true (or present); or both A and B are true (or present).

All technical features and optional technical features of the present application may be combined with each other to form new technical solutions, unless specified otherwise.

All embodiments and alternative embodiments of the present application may be combined with each other to form new solutions, unless specifically stated otherwise.

Unless otherwise indicated, the following terms have the following meanings. Any undefined terms have their art-recognized meanings.

Next, various embodiments of the present application are described.

The heat conduction silicone grease is a high heat conduction and insulation organic silicon material, and is widely applied because the heat conduction silicone grease can be filled in gaps below 50 mu m, has high electrical insulation property, high heat conduction efficiency and simple and convenient cleaning.

The heat conduction silicone grease is mainly prepared by taking organic silicone as a main raw material and adding materials with excellent heat resistance and heat conduction performance, and the prepared heat conduction silicone grease-like compound can be coated on electronic components or heat dissipation facilities in electronic equipment or electric equipment to play a role of heat transfer medium so as to ensure the stability of the electrical performance of electronic instruments, meters and the like. The heat conduction silicone grease can be filled between the battery module and the radiating fin, so that the radiating fin is better contacted with the battery module, and the radiating effect is improved; meanwhile, the heat conduction silicone grease can reduce the heat resistance between the radiating fin and the battery module, so that heat is conducted to the external environment more rapidly. The heat dissipation of the battery has a critical effect on the performance and the service life of the battery, and materials such as heat conduction silicone grease can also improve the heat dissipation effect to a certain extent.

With the continuous development of new energy industry, the electric power of the electric automobile is continuously increased, and higher requirements are put forward on the used heat conduction silica gel, so that the market demand cannot be met by pursuing high heat conduction performance singly. The present-day heat-conducting silicone grease exhibits a relatively high dielectric constant, which may interfere with electrical signal transmission to affect normal operation of the device when applied to high-power electronic devices, and has low reliability under relatively severe environments, such as: the high temperature and humidity (85 ℃ and 85%) and high and low temperature circulation (-40 to 150 ℃) scenes are easy to oil out to pollute the base material, the silicone grease is easy to heat conduction failure after dry cracking and pulverization, and the scattering of heat conduction powder can also influence the safety of the device. Therefore, how to realize the heat conduction silicone grease has lower dielectric constant and high reliability while ensuring excellent heat conduction performance becomes a breakthrough in technology.

In view of this, embodiments of the present application provide a thermally conductive silicone grease comprising: silicone oil, heat conducting filler and fluorine-containing silane coupling agent. By introducing the fluorine-containing silane coupling agent, the fluorine-containing silane coupling agent can be hydrolyzed to chemically react with the heat-conducting filler to form hydroxyl, and has good compatibility with the silicone oil, so that the fluorine-containing silane coupling agent can be used as a bridge for connecting the heat-conducting filler and the silicone oil, and the structural stability of the heat-conducting silicone grease is improved; and the introduction of fluorine atoms can enable the heat-conducting silicone grease to show a lower dielectric constant; meanwhile, the self-lubricating effect brought by fluorine atoms can effectively inhibit aggregation of the heat conducting filler, so that the heat silicone grease conducted by the embodiment of the application can have the advantages of excellent heat conducting property, low dielectric constant and high reliability.

The heat-conducting silicone grease of the embodiment of the application can be used in various electronic devices, particularly high-power electronic devices such as electric automobiles, and the embodiment of the application is not limited to the above.

[ Heat conduction Silicone grease ]

The embodiment of the application provides a heat conduction silicone grease, which comprises: silicone oil, heat conducting filler and fluorine-containing silane coupling agent.

Wherein the fluorine-containing silane coupling agent is a silane coupling agent containing fluorine element. Silane coupling agents are a class of organosilicon compounds that contain two groups of different chemical nature in the molecular structure at the same time. The silane coupling agent may be exemplified by the general formula Y _n SiX _4-n Expressed by 1.ltoreq.n<4, n is an integer, wherein X is a group that can hydrolyze and form Si-OH, such as Cl, OMe, OEt, etc., X can have the ability to bond to some inorganic materials; y being a non-hydrolysing group, e.g. alkenyl, terminated with Cl, F, NH ₂ Compatibility of the hydrocarbon groups of the groups SH, epoxy, (meth) acryloyloxy, and the like, Y with the polymer. The fluorine-containing silane coupling agent may be, for example, a hydrocarbon group in which Y is a terminal F group in the general formula.

In the heat-conducting silicone grease, on one hand, the fluorine-containing silane coupling agent can be subjected to chemical reaction with the heat-conducting filler to form hydroxyl groups through hydrolysis, and has good compatibility with silicone oil, so that the fluorine-containing silane coupling agent can be used as a bridge for connecting the heat-conducting filler with the silicone oil to form a compact heat-conducting network, and the structural stability of the heat-conducting silicone grease can be cooperatively improved, so that the characteristics of low oil separation degree and high reliability can be shown; in the second aspect, electronegativity of fluorine atoms is highest in elements, so that fluorocarbon bond electron clouds are mostly concentrated at one end of the fluorine atoms, thereby reducing the polarizability and enabling the electron distribution to be more uniform, and introduction of the fluorine atoms can increase free volume, thereby reducing the number of polarized groups in unit volume, so that the heat-conducting silicone grease can be enabled to show lower dielectric constant; on the other hand, because of the existence of fluorine atoms, the polarity of the fluorocarbon bonds is small, and the intermolecular acting force of the compound containing the fluorocarbon bonds is low, so that the surface energy is low, the self-lubricating property is realized, the self-lubricating effect can effectively inhibit the aggregation of the heat conducting filler, the uneven heat conduction of the heat conducting silicone grease is prevented, the promotion of the compatibility between the heat conducting filler is facilitated, a good heat conducting network is formed, and the good heat conducting property is shown; in addition, most fluorine-containing silane coupling agents are produced in mass, can be directly purchased in the market, and have higher maturity and extremely high experimental repeatability. In summary, the heat-conducting silicone grease of the embodiment of the application can have excellent heat-conducting performance, low dielectric constant and high reliability.

Alternatively, the fluorine-containing silane coupling agent may include one or more of perfluorodecyl triethoxysilane, perfluorooctyl triethoxysilane, trifluoropropane trimethoxysilane, and nonafluorohexyl trimethoxysilane.

Based on the above embodiments, the impurity content in the mixture can be reduced.

In some embodiments, the fluorine-containing silane coupling agent may include perfluorodecyl triethoxysilane.

In some embodiments, the fluorine-containing silane coupling agent may be contained in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of the thermally conductive silicone grease.

Based on the embodiment, the fluorine-containing silane coupling agent in the heat-conducting silicone grease can achieve better coupling, and is favorable for improving the compatibility between the heat-conducting fillers to form a good heat-conducting network, so that good heat-conducting performance can be shown. Illustratively, the content of the fluorine-containing silane coupling agent may be 0.1 part by weight, 0.3 part by weight, 0.5 part by weight, 0.7 part by weight, 1 part by weight, 1.3 parts by weight, 1.5 parts by weight, 1.7 parts by weight, 2 parts by weight, and a range value between any two of the foregoing.

In some embodiments, the fluorine-containing silane coupling agent may be contained in an amount of 0.5 to 2 parts by weight based on 100 parts by weight of the thermally conductive silicone grease.

Based on the embodiment, the fluorine-containing silane coupling agent in the heat-conducting silicone grease can further achieve better coupling, and is favorable for improving the compatibility between the heat-conducting fillers to form a good heat-conducting network, so that good heat-conducting performance can be shown.

Alternatively, the silicone oil may include one or more of methyl silicone oil, benzyl silicone oil, vinyl silicone oil, hydrogen-containing silicone oil, amino silicone oil, hydroxyl silicone oil, and fluorine-containing silicone oil.

Among these, methyl silicone oil, or referred to as dimethicone, is a linear polymer of dimethicone, which has different viscosities depending on the degree of polymerization. The benzyl silicone oil is composite silicone oil of polymer with phenyl introduced into the molecular chain of dimethyl siloxane, and is the product of methyl silicone oil with partial methyl replaced by phenyl. Vinyl silicone oils are mainly vinyl terminated polydimethylsiloxanes and vinyl terminated polymethylvinylsiloxanes. Hydrogen-containing silicone oils, alternatively referred to as polymethylhydrosiloxanes, are polysiloxanes containing reactive Si-H bonds in the molecule. The amino silicone oil is amino modified polysiloxane with a side chain provided with diamine groups. Hydroxy silicone oil, also called dimethyl hydroxy silicone oil, has the structural formula HO [ (CH) ₃ ) ₂ SiO] _m H, where m may be an integer between 1 and 200, is a hydroxyl terminated polysiloxane. The fluorine-containing silicone oil is fluorine-containing polysiloxane such as trifluoropropyl methyl silicone oil.

In some embodiments, the silicone oil may include one or more of methyl silicone oil, vinyl silicone oil, hydrogen-containing silicone oil, amino silicone oil, and hydroxyl silicone oil.

Alternatively, in some embodiments, the silicone oil may be present in an amount of 5-35 parts by weight based on 100 parts by weight of the thermally conductive silicone grease.

In some embodiments, the silicone oil may be present in an amount of 5-25 parts by weight based on 100 parts by weight of the thermally conductive silicone grease. Illustratively, the silicone oil may be present in an amount of 5 parts by weight, 9 parts by weight, 15 parts by weight, 18 parts by weight, 25 parts by weight, 32 parts by weight, 35 parts by weight, and any range therebetween.

In some embodiments, the thermally conductive filler may include an inorganic filler.

In some embodiments, the inorganic filler may include one or more of metal oxides, metal nitrides, silicon oxides, silicon carbides, silicon nitrides, boron oxides, boron carbides, and boron nitrides.

Preferably, the inorganic filler may include one or more of aluminum oxide, zinc oxide, magnesium oxide, aluminum nitride, boron nitride, and silicon dioxide.

Alternatively, in some embodiments, the thermally conductive filler may be present in an amount of 64-94 parts by weight, optionally 85-94 parts by weight, based on 100 parts by weight of the thermally conductive silicone grease. Illustratively, the thermally conductive filler may be present in an amount ranging from 64 parts by weight, 70 parts by weight, 75 parts by weight, 85 parts by weight, 90 parts by weight, 94 parts by weight, and any range therebetween. Based on the above embodiment, the heat conductive filler in the heat conductive silicone grease is in the range, which is favorable for forming a compact heat conductive network, and can improve the structural stability of the heat conductive silicone grease, thereby being capable of showing the characteristics of low oil separation degree and high reliability.

Alternatively, in some embodiments, the particle size of the thermally conductive filler may range from 0.1 to 50 μm, preferably from 0.5 to 40 μm. Wherein, the granularity range is a published technical term of material science and represents the granularity change interval or amplitude of particles in a certain grading powder. Illustratively, the particle size of the thermally conductive filler is in the range of 0.1 to 50 μm, meaning that the thermally conductive filler falls between two layers of sieves having mesh sizes of 0.1 μm and 50 μm, respectively.

In some embodiments, the thermally conductive silicone grease may also include other components, such as one or more of antioxidants, colorants, stabilizers, wetting agents, antiwear agents, rust inhibitors, and the like.

Having described embodiments of the thermally conductive silicone grease of the present application above, embodiments of a method of preparing the thermally conductive silicone grease will be described in detail below. In embodiments of methods of preparing thermally conductive silicone grease, non-described portions may be referred to in connection with descriptions of embodiments of thermally conductive silicone grease.

[ preparation method of Heat conductive Silicone grease ]

Fig. 1 is a schematic diagram of a preparation method of a heat-conducting silicone grease according to an embodiment of the present application. The preparation method of the heat-conducting silicone grease comprises the following steps:

110, performing cleaning treatment and drying treatment on the heat-conducting filler to obtain a pretreated filler;

120, performing dispersion treatment on the fluorine-containing silane coupling agent and the pretreated filler to obtain modified filler;

130, mixing the modified filler with silicone oil, and performing grinding treatment to obtain semi-finished silicone grease;

140, stirring the semi-finished silicone grease to obtain the heat-conducting silicone grease.

Among them, the washing treatment and the drying treatment may belong to pretreatment of the heat conductive filler.

In some embodiments, the washing process may be performed using an organic solvent, such as a hydrocarbon (e.g., alkane, aromatic, etc.), chlorinated hydrocarbon, fluorinated hydrocarbon, alcohol ether, etc. solvent.

Based on the above embodiments, the cleaning treatment can directly dissolve some substances that are easily soluble in organic solvents, such as grease, wax, resin, rubber, dye, some colloidal substances, etc., or can dissolve some organic dirt and remove the above impurities during the cleaning process.

Optionally, the cleaning treatment can be performed by using absolute ethyl alcohol, so that impurities and moisture contained on the surface of the heat conducting filler are removed, and the absolute ethyl alcohol volatilizes faster.

In some embodiments, ultrasound may also be used for auxiliary cleaning. In particular, the cleaning treatment may include ultrasonic dispersion. For example, absolute ethanol may be added to the heat conductive filler and ultrasonically dispersed. Alternatively, the duration of the ultrasonic dispersion may be 5-12 hours. Illustratively, the duration of the ultrasonic dispersion may be 5h, 7h, 9h, 10h, 11h, 12h and ranges between any of the two.

Based on the above embodiment, the auxiliary cleaning by using the ultrasonic wave can improve the cleaning effect and is beneficial to avoiding the cleaned oil stains from being reattached to the heat conductive filler.

Alternatively, the drying process may include vacuum drying. Specifically, the heat conductive filler after ultrasonic dispersion may be placed in a vacuum drying oven for vacuum drying. Alternatively, the temperature of the vacuum drying may be set to 60-80 ℃. Illustratively, the temperature of the vacuum drying may be 60 ℃, 65 ℃, 70 ℃, 75 ℃, 80 ℃ and ranges between any of the two.

In some embodiments, the dispersing treatment may include stirring the fluorine-containing silane coupling agent and the pretreatment filler by a stirrer.

In some embodiments, the dispersion treatment may include pre-dispersing the fluorosilane coupling agent and the pretreatment filler by stirring the mixture at a low speed with a stirrer, followed by further dispersion with stirring at a high speed.

Specifically, the fluorine-containing silane coupling agent and the pretreatment filler can be stirred at a first rotating speed to obtain a pre-dispersed filler, and then the pre-dispersed filler is stirred at a second rotating speed to perform ultrasonic collaborative dispersion to obtain a modified filler, wherein the first rotating speed is smaller than the second rotating speed.

Alternatively, the first rotational speed may be 20-650rpm/min. Alternatively, the first rotational speed may be 20-450rpm/min. By way of example, the first rotational speed may be 20rpm/min, 100rpm/min, 350rpm/min, 450rpm/min, 550rpm/min, 650rpm/min, and ranges between any two of the foregoing. Further, the duration of stirring at the first rotational speed may be 5-30 minutes. For example, the duration of the first rotational speed agitation may be 5 minutes, 10 minutes, 25 minutes, 30 minutes, and ranges between any of the two.

Alternatively, the second rotational speed may be 500-1300 rpm/min. Further, the duration of stirring at the second rotational speed may be 10 to 30 minutes. By way of example, the second rotational speed may be 500rpm/min, 800rpm/min, 900rpm/min, 1000rpm/min, 1150rpm/min, 1300rpm/min and range values therebetween. For example, the duration of stirring at the second rotational speed may be 10min, 15min, 20min, 25min, 30min and ranges between any of the two.

Alternatively, the frequency of the ultrasound co-dispersed by the ultrasonic machine may be 20-55kHz. By way of example, the frequency of the ultrasound may be 20kHz, 30kHz, 45kHz, 55kHz and ranges between any of the two.

In some embodiments, the grinding treatment may include grinding the modified filler with silicone oil through a three-roll mill until no particles are present, resulting in the semi-finished silicone grease.

In some embodiments, the semi-finished silicone grease is subjected to a stirring process that includes evacuating at a temperature of 80-200 ℃ and stirring to obtain a thermally conductive silicone grease. Specifically, the temperature can be set to 80-200 ℃, and the heat conduction silicone grease can be obtained by vacuumizing and uniformly stirring. Illustratively, the temperature may be set to a range of values of 80 ℃, 120 ℃, 150 ℃, 180 ℃, 200 ℃ and any two thereof.

Optionally, the semi-finished silicone grease can be put into a planetary mixer, heated to 80-200 ℃, vacuumized and uniformly stirred to obtain the heat-conducting silicone grease.

The application also provides application of the heat-conducting silicone grease in electronic equipment.

Illustratively, the heat-conducting silicone grease according to any one of the above embodiments may be applied to a high-power electronic device. For example, it can be used for heat dissipation of energy storage cabinets in automobiles. For example, a direct current/direct current (DC/DC) converter that can be used in automotive products; in particular, it is useful for solving the problem of heat dissipation of a printed circuit board (printed circuit board, PCB) of a DC/DC converter in an automobile.

Examples (example)

The following examples more particularly describe the disclosure of the present application, which are intended as illustrative only, since numerous modifications and variations within the scope of the disclosure will be apparent to those skilled in the art. The embodiments described below are exemplary only for the purpose of illustrating the present application and are not to be construed as limiting the present application. The examples are not to be construed as limiting the specific techniques or conditions described in the literature in this field or as per the specifications of the product. Unless otherwise indicated, all parts, percentages, and ratios reported in the examples below are by weight, and all reagents used in the examples are commercially available or were obtained synthetically according to conventional methods and can be used directly without further treatment, as well as the instruments used in the examples.

Example 1

The heat-conducting silicone grease of the material composition and metering formulation example 1 comprises 45g of silicone oil, 5g of fluorine-containing silane coupling agent and 450g of heat-conducting filler, wherein the silicone oil is dimethyl silicone oil with the viscosity of 1000 mPas, the fluorine-containing silane coupling agent is perfluorodecyl triethoxysilane with the purity of more than or equal to 98%, and the heat-conducting filler is aluminum oxide and zinc oxide, and the mass ratio of the aluminum oxide to the zinc oxide is 3:1; the particle size range is 0.5-35 μm.

Pretreatment of the manufacturing process: dripping a small amount of absolute ethyl alcohol into the heat-conducting filler, performing ultrasonic dispersion for 12 hours, and placing the heat-conducting filler after the ultrasonic treatment into a vacuum drying oven with the set temperature of 80 ℃ for vacuum drying to obtain a pretreated filler;

and (3) dispersion treatment: stirring the pretreated filler and the fluorine-containing silane coupling agent for 10min at normal temperature through an electric stirrer at a lower rotating speed of 200 rpm/min until the pretreated filler and the fluorine-containing silane coupling agent are uniformly mixed for pre-dispersion treatment; stirring at a high speed at a rotating speed of 1000rpm/min, and placing in an ultrasonic dispersing machine to perform synergistic dispersion for 20min at a frequency of 30kHz to obtain modified filler;

grinding: adding the modified filler and silicone oil into a three-roller grinder, and grinding until the modified filler and silicone oil are fine and smooth and have no particles, thus obtaining semi-finished silicone grease;

stirring: and (3) placing the semi-finished silicone grease into a planetary stirrer, heating to 150 ℃, vacuumizing and defoaming, and uniformly stirring to obtain the heat-conducting silicone grease.

Example 2

The other differences are as in example 1, except that the fluorine-containing silane coupling agent is changed from perfluorodecyl triethoxysilane to perfluorooctyl triethoxysilane.

Example 3

The other points are the same as in example 1, except that the fluorine-containing silane coupling agent is changed from perfluorodecyl triethoxysilane to nonafluorohexyl trimethoxysilane.

Example 4

The other points are the same as in example 1 except that the fluorine-containing silane coupling agent is changed from perfluorodecyl triethoxysilane to trifluoropropane trimethoxysilane.

Examples 5 to 8

The other differences are only those of example 1, in which the weight percentages of the materials are shown in Table 1.

Examples 9 to 12

The other differences are as in example 1, except that the weight percentages of the materials are as shown in Table 1.

Example 13

The other differences are just that in example 1, the silicone oil is replaced by a vinyl silicone oil from a dimethyl silicone oil.

Example 14

The other differences are just that in example 1, the silicone oil is changed from dimethicone to methyl fluorosilicone.

Examples 15 to 16

Comparative example 1

The other points are the same as in example 1 except that the fluorine-containing silane coupling agent is replaced with a kh-570 silane coupling agent (or referred to as 3-methacryloxypropyl trimethoxysilane) containing no fluorine element.

The parameters of the thermally conductive silicone greases of examples 1 to 16 and comparative example 1 are shown in Table 1.

Table 1: product parameters of the different examples and comparative examples

Comparative example 2

The other difference from example 1 is that the heat conductive silicone grease was prepared without pretreatment of the heat conductive filler, i.e., without washing and drying of the heat conductive filler.

Comparative example 3

The other difference is that the modified filler is not pre-dispersed when being mixed with silicone oil in the preparation process of the heat-conducting silicone grease, but is directly subjected to high-speed stirring and ultrasonic collaborative dispersion.

Test part

(1) The heat conductivity testing method comprises the following steps:

and (3) measuring the heat conductivity coefficient of the heat-conducting silicone grease by using a heat conduction instrument with the model of Hot Disk TPS 2500S according to the measurement of the heat conductivity coefficient and the heat diffusion coefficient of the plastic of the international standard ISO 22007-2 by using a transient plane heat source method, and taking an average value of three parallel samples measured in each group.

(2) The dielectric constant test method comprises the following steps:

the dielectric constant measurement was performed on the conductive silicone grease using an LCR tester model E4980AL according to standard test methods for ac loss characteristics and permittivity (dielectric constant) of solid electrical insulation material of American standard ASTM D150, wherein the test frequency was 100Hz.

(3) The reliability testing method comprises the following steps:

and (3) adopting a constant temperature and constant humidity test box with the model XB-OTS-150B-B, referring to the environmental test of national standard GB/T2423.50-2012, and performing aging test on a test body under the conditions that the environment is set to be 85 ℃ and the humidity is 85%, wherein the time is 1000 hours, and mainly detecting the limit that the heat conduction silicone grease can bear under the severe environment of high temperature and high humidity. This method may also be referred to as double 85 aging for 1000 hours.

(4) The particle size range testing method comprises the following steps:

the test was performed using an European and American laser particle sizer model LS-609, with reference to national standard GB/T19077-2016, particle size distribution laser diffraction method.

Test results

The results of the performance tests of the thermally conductive silicone greases of examples 1 to 16 and comparative example 1 described above are shown in Table 2.

TABLE 2 results of Performance test of examples 1-16 and comparative example 1

Referring to examples 1-4 and comparative example 1 in Table 2, the dielectric constant of comparative example 1 is greatly increased and the thermal conductivity is lower than that of examples 1-4. The comparative analysis shows that the addition of the fluorine-containing silane coupling agent can greatly reduce the dielectric constant and increase the heat conductivity, probably because the fluorine-containing silane coupling agent has fluorocarbon bonds, the introduction of fluorine provides extremely low dielectric constant for the heat-conducting silicone grease, and the fluorine has self-lubricating effect, can effectively inhibit the aggregation of the heat-conducting filler, and is beneficial to forming a good heat-conducting network, so that the heat-conducting silicone grease with the fluorine-containing silane coupling agent shows low dielectric constant and good heat-conducting property.

The results of the performance tests of the thermally conductive silicone greases of examples 1 to 8 and comparative examples 2 to 3 described above are shown in Table 3.

TABLE 3 results of Performance test of examples 1-8 and comparative examples 2-3

Referring to examples 1-4 and comparative example 2 in Table 3, the heat conductive silicone grease of comparative example 2 exhibited slight dry cracking after being subjected to the double 85 aging 1000 hours test compared to examples 1-4, and had inferior reliability compared to examples 1-4, and had lower heat conductivity and higher dielectric constant. Fig. 2 and 3 are schematic diagrams showing the results of the reliability test of example 1 and comparative example 2, respectively, and it can be seen that the heat conductive silicone grease of example 1 did not crack, while the heat conductive silicone grease of comparative example 2 exhibited slight surface dryness. According to comparative analysis, impurities and moisture on the surface of the heat-conducting filler can be effectively removed after the heat-conducting filler is subjected to cleaning treatment and drying treatment, so that the compatibility of the silane coupling agent and the heat-conducting filler is improved, and the heat-conducting silicone grease subjected to the preparation process including the cleaning treatment and the drying treatment has higher heat-conducting performance, higher reliability and lower dielectric constant.

Further, referring to examples 1-4 and comparative example 3 in Table 3, the heat conductive silicone grease of comparative example 3 also exhibited slight dry cracking after being subjected to the double 85 aging 1000h test as compared with examples 1-4, and was inferior in reliability as compared with examples 1-4, and was lower in heat conductivity and higher in dielectric constant. Comparative analysis shows that in the preparation process comprising the pre-dispersed heat-conducting silicone grease, the contact surface between the heat-conducting filler and the silane coupling agent can be increased in the pre-dispersion process, so that the compatibility of the heat-conducting filler and the silane coupling agent is improved. Thus, the preparation process comprising the pre-dispersed heat conduction silicone grease has excellent heat conduction performance, extremely low dielectric constant and better reliability.

The present application is not limited to the above embodiment. The above embodiments are merely examples, and embodiments having substantially the same configuration and the same effects as those of the technical idea within the scope of the present application are included in the technical scope of the present application. Further, various modifications that can be made to the embodiments and other modes of combining some of the constituent elements in the embodiments, which are conceivable to those skilled in the art, are also included in the scope of the present application within the scope not departing from the gist of the present application.

Claims

1. A thermally conductive silicone grease, characterized in that the thermally conductive silicone grease comprises: silicone oil, heat conducting filler and fluorine-containing silane coupling agent.

2. The heat conductive silicone grease according to claim 1, wherein the fluorine-containing silane coupling agent is contained in an amount of 0.1 to 2 parts by weight based on 100 parts by weight of the heat conductive silicone grease.

3. The heat conductive silicone grease according to claim 2, wherein the fluorine-containing silane coupling agent is contained in an amount of 0.5 to 2 parts by weight based on 100 parts by weight of the heat conductive silicone grease.

4. The thermally conductive silicone grease of claim 1, wherein the fluorine-containing silane coupling agent comprises one or more of perfluorodecyl triethoxysilane, perfluorooctyl triethoxysilane, trifluoropropane trimethoxysilane, nonafluorohexyl trimethoxysilane.

5. The thermally conductive silicone grease of claim 4, wherein the fluorine-containing silane coupling agent comprises the perfluorodecyl triethoxysilane.

6. The heat conductive silicone grease according to any one of claims 1 to 5, wherein the silicone oil is contained in an amount of 5 to 35 parts by weight based on 100 parts by weight of the heat conductive silicone grease.

7. The heat conductive silicone grease according to claim 6, wherein the silicone oil is contained in an amount of 5 to 25 parts by weight based on 100 parts by weight of the heat conductive silicone grease.

8. The heat conductive silicone grease according to any one of claims 1-5, wherein the silicone oil comprises one or more of a methyl silicone oil, a benzyl silicone oil, a vinyl silicone oil, a hydrogen-containing silicone oil, an amino silicone oil, a hydroxyl silicone oil, and a fluorine-containing silicone oil.

9. The thermally conductive silicone grease of claim 8, wherein the silicone oil comprises one or more of the methyl silicone oil, the vinyl silicone oil, the hydrogen-containing silicone oil, the amino silicone oil, and the hydroxyl silicone oil.

10. The heat conductive silicone grease according to any one of claims 1 to 5, wherein the content of the heat conductive filler is 64 to 94 parts by weight based on 100 parts by weight of the heat conductive silicone grease.

11. The heat conductive silicone grease according to claim 10, wherein the content of the heat conductive filler is 85 to 94 parts by weight based on 100 parts by weight of the heat conductive silicone grease.

12. The thermally conductive silicone grease of any one of claims 1 to 5, wherein the thermally conductive filler comprises an inorganic filler.

13. The thermally conductive silicone grease of claim 12, wherein the inorganic filler comprises one or more of a metal oxide, a metal nitride, a silicon oxide, a silicon carbide, a silicon nitride, a boron oxide, a boron carbide, and a boron nitride.

14. The thermally conductive silicone grease of claim 13, wherein the inorganic filler comprises one or more of aluminum oxide, zinc oxide, magnesium oxide, aluminum nitride, boron nitride, silicon dioxide.

15. The thermally conductive silicone grease according to any one of claims 1-5, wherein the thermally conductive filler has a particle size in the range of 0.1-50 μm.

16. The thermally conductive silicone grease of claim 15, wherein the thermally conductive filler has a particle size in the range of 0.5-40 μm.

17. A method of preparing a thermally conductive silicone grease, the method comprising:

cleaning and drying the heat-conducting filler to obtain a pretreated filler;

dispersing the fluorine-containing silane coupling agent and the pretreated filler to obtain modified filler;

mixing the modified filler with silicone oil, and grinding to obtain semi-finished silicone grease;

stirring the semi-finished silicone grease to obtain the heat-conducting silicone grease.

18. The method of claim 17, wherein the cleaning treatment comprises ultrasonic dispersion; and/or the number of the groups of groups,

the drying treatment includes vacuum drying.

19. The method of claim 18, wherein the duration of the ultrasonic dispersion is 5-12 hours and/or the temperature of the vacuum drying is 60-80 ℃.

20. The production method according to any one of claims 17 to 19, wherein the dispersion treatment comprises:

stirring the fluorine-containing silane coupling agent and the pretreatment filler at a first rotational speed to obtain a pre-dispersed filler;

stirring the pre-dispersed filler at a second rotating speed, and performing ultrasonic collaborative dispersion to obtain the modified filler, wherein the first rotating speed is smaller than the second rotating speed.

21. The method of claim 20, wherein the first rotational speed is 20-650 rpm/min; and/or the second rotating speed is 500-1300 rpm/min; and/or the frequency of the ultrasonic synergistic dispersion is 20-55kHz; and/or the number of the groups of groups,

the duration of stirring at the first rotational speed is 5-30min; and/or stirring at the second rotating speed for 10-30min.

22. The production method according to any one of claims 17 to 19, wherein the stirring treatment comprises:

vacuumizing at 80-200deg.C, and stirring to obtain the heat-conducting silicone grease.

23. Use of the thermally conductive silicone grease of any one of claims 1 to 16 or the thermally conductive silicone grease prepared by the preparation method of any one of claims 17 to 22 in an electronic device.