Single-component heat-conducting silica gel and preparation method thereof

Abstract

The invention belongs to the field of heat-conducting interface materials, and particularly provides single-component heat-conducting silica gel and a preparation method thereof. The single-component heat-conducting silica gel comprises the following components in parts by weight: 20-50 parts of vinyl silicone oil, hydrogen-containing silicone oil, 500-2000 parts of heat-conducting filler, 1-100 parts of functional additive, 1-4 parts of catalyst and 0-8 parts of pigment, the mass ratio of the hydrogen-containing silicone oil to the vinyl silicone oil is (0.2-5): 100; the functional auxiliary agent is alkoxy-terminated polysiloxane with a structure as shown in a formula 1. The single-component heat-conducting silica gel disclosed by the invention not only shows excellent extrusion performance, but also has higher heat-conducting property and lower oil separation property. # imgabs0 #

Description

Technical Field

[0001] The invention relates to the field of thermal interface materials, and in particular provides a single-component thermally conductive silicone gel and a preparation method thereof. Background Art

[0002] With the continuous improvement of the integration level and power density of electronic devices, efficient thermal management has become a key factor affecting the reliability of equipment. At present, the single-component thermal conductive gel on the market is usually a new type of interface filling thermal conductive material (TIM) with pre-curing, low oil separation and low assembly stress. It is widely used in the heat dissipation interface of electronic devices. The main specific applications include the following aspects: 1) Heat dissipation of electronic equipment; for example, whether it is a mobile phone, tablet or computer, its normal operation is inseparable from the heat conduction effect of thermal conductive materials, and single-component thermal conductive gel, as a common thermal conductive material, has become an important choice for electronic equipment heat dissipation with its excellent thermal conductivity and excellent compressibility; 2) IC packaging and electronic heat dissipation; TIM is a part of IC packaging and heat dissipation. Common methods, among which, single-component thermal conductive gel can connect IC chip and radiator, and conduct heat from IC chip to radiator by filling the gap between chip and radiator, and then the radiator takes away the heat to cool the equipment; 3) Automotive electronics: single-component thermal conductive gel is used as heat transfer material between driving module components and shell of automotive electronics to ensure heat dissipation of automobile; 4) LED lighting devices: single-component thermal conductive gel can partially fill the driving power supply of lighting devices, so as to effectively export heat and avoid the problem of frequent replacement due to uneven heat dissipation of power supply, thus saving costs.

[0003] Current thermal conductive gel materials pursue high extrusion rate, low oil separation property, and high thermal conductivity. High extrusion rate is a rigid requirement for the processing performance of materials in industrial production. Material properties such as low viscosity and high thixotropy can significantly improve the encapsulation efficiency and reduce the process energy consumption. However, to achieve a high thermal conductivity coefficient, a large amount of thermal conductive fillers must be introduced into the gel material, which in turn leads to an exponential increase in the system viscosity. The oil separation index represents the proportion of liquid components such as silicone oil precipitating from the gel matrix during long-term use of the gel material, and it is a core parameter for measuring its thermal stability and interface reliability. However, the current filler-matrix compatibility problem easily causes significant oil separation: when the filler mass exceeds 60%, the interfacial tension between the silicone matrix and the filler is prone to imbalance, resulting in filler sedimentation. This will not only reduce the thermal conduction stability during the service life of the material, but also pose a risk of internal electrical short circuit in the device. To reduce oil separation, it is often necessary to add some powders with a high oil absorption value or increase the crosslinking density to the gel material, but this will lead to a decrease in the extrusion rate. Moreover, when the thermal conductivity increases, the system viscosity and oil separation rate will increase significantly. The non-linear correlation of the above three parameters limits the application of traditional thermal conductive gels and makes it difficult to meet the stringent requirements of high thermal conductivity, low oil separation, and high-speed dispensing of materials in scenarios such as 5G base stations and IGBT modules. Summary of the Invention

[0004] Aiming at the above problems existing in the prior art, the object of the present invention is to provide a one-component thermal conductive silicone gel and its preparation method. The one-component thermal conductive silicone gel not only exhibits excellent extrusion performance, but also has higher thermal conductivity and lower oil separation property.

[0005] In the first aspect, the present invention provides a one-component thermal conductive silicone gel, comprising: 20-50 parts by weight of vinyl silicone oil, hydrogen-containing silicone oil, 500-2000 parts by weight of thermal conductive filler, 1-100 parts by weight of functional additive, 1-4 parts by weight of catalyst, and 0-8 parts by weight of pigment; and the mass ratio of the hydrogen-containing silicone oil to the vinyl silicone oil is (0.2-5):100; the functional additive is an alkoxy-terminated polysiloxane having a structure shown in Formula 1:

[0006]

[0007] In Formula 1, each R1, each R2, and each R3 are the same or different from each other, and are independently selected from alkyl groups having 1-5 carbon atoms; each L1 and each L2 are the same or different from each other, and are independently selected from a single bond or an alkylene group having 1-5 carbon atoms; m and n represent the degree of polymerization.

[0008] The one-component thermally conductive silicone gel of the present invention belongs to an addition-type thermally conductive silicone gel with a high filling amount. Under the action of a catalyst, the vinyl silicone oil therein can react with the hydrogenated silicone oil to form an elastomer with a three-dimensional network, and the thermally conductive filler with a high filling amount can form a continuous thermal conduction path to ensure the thermal conductivity of the gel. In particular, among the functional aids used, the trialkoxy groups at both ends of the main chain of the molecular structure can chemically react with the hydroxyl groups on the surface of the thermally conductive filler, improving the interfacial bonding force between the filler and the organosilicon matrix, reducing the oil separation property. The side chain with vinyl can not only participate in crosslinking to enhance the network stability but also act as a flexible chain segment to improve the fluidity of the system, enabling the high filling system to still maintain excellent extrusion performance. Moreover, based on controlling the hydrogenated silicone oil to have a relatively low content with the vinyl silicone oil, the one-component thermally conductive silicone gel can be in a paste state (in an incompletely cured state), without hardness characteristics, and is particularly suitable for use as a functional material (such as a new type of interface filling thermally conductive material).

[0009] In some embodiments of the present invention, the hydrogenated silicone oil is end-hydrogenated silicone oil and / or side-hydrogenated silicone oil.

[0010] In some embodiments of the present invention, in the one-component thermally conductive silicone gel, the molar ratio of the hydrogen groups in the hydrogenated silicone oil to the vinyl groups in the vinyl silicone oil is (0.1 - 0.5):1. In this way, the one-component thermally conductive silicone gel is more likely to present a soft paste state.

[0011] In some embodiments of the present invention, the vinyl silicone oil is selected from at least one of vinyl-terminated polydimethylsiloxane, polymethylphenyl-methylvinylsiloxane, and methyl-terminated and side-chain vinyl-containing polysiloxane.

[0012] In some embodiments of the present invention, the vinyl content in the vinyl silicone oil is 0.1 - 0.5 mmol / g, and the viscosity at 25 °C is 10 - 600 mPa·s.

[0013] In some embodiments of the present invention, in Formula 1, each R1, each R2, and each R3 are independently selected from methyl or ethyl, and each L1 and each L2 are independently selected from a single bond, methylene, or ethylene.

[0014] In some embodiments of the present invention, m is 10 - 100, and n is 10 - 50.

[0015] In some embodiments of the present invention, the viscosity of the alkoxy-terminated polysiloxane at 25 °C is 20 - 100 cSt.

[0016] In some embodiments of the present invention, the functional auxiliary agent is prepared by a method comprising the following steps: in the presence of a platinum catalyst and under the protection of an inert atmosphere, a hydrosilylation reaction is carried out on reactants, wherein the reactants consist of an end-side hydrogen-containing silicone oil represented by formula a, a monoalkenylalkoxysilicone oil represented by formula b, and a diene-based disiloxane represented by formula c:

[0017]

[0018] Further, relative to the total mass of the reactants, the mass dosage of the platinum catalyst accounts for 5-20 ppm; in the reactants, the sum of the monoalkenylalkoxysilicone oil and the diene-based disiloxane and the relative dosage of the end-side hydrogen-containing silicone oil are in a molar ratio of vinyl groups to hydrogen groups of 1:(0.8-2).

[0019] Further, the molar ratio of the monoalkenylalkoxysilicone oil to the diene-based disiloxane is 1:(1-10).

[0020] Further, the hydrosilylation reaction is carried out under stirring conditions, the reaction temperature is 90-130 °C, and the reaction time is 1-5 h.

[0021] In some embodiments of the present invention, the heat-conducting filler is selected from at least one of metal fillers, carbon materials, and inorganic non-metallic fillers.

[0022] Further, the heat-conducting filler is selected from at least two of diamond, aluminum nitride, alumina, magnesia, boron nitride, silicon carbide, zinc oxide, aluminum hydroxide, and silica powder.

[0023] In some embodiments of the present invention, based on the total weight of the heat-conducting filler, those with a particle size D50 of 0.1-3 μm account for 10%-25%, those with a particle size D50 of 5-15 μm account for 10%-30%, and those with a particle size D50 of 40-90 μm account for 45%-70%.

[0024] In some embodiments of the present invention, the catalyst is selected from at least one of chloroplatinic acid, platinum-vinylsiloxane complex, and platinum-alkynyl chelate.

[0025] In some embodiments of the present invention, the pigment is selected from at least one of carbon black, iron red, cobalt blue, and cadmium yellow.

[0026] In a second aspect, the present invention provides a method for preparing the one-component heat-conducting silicone gel described in the first aspect of the present invention, comprising the following steps:

[0027] Carry out a first mixing of the vinyl silicone oil, hydrogen-containing silicone oil, heat-conducting filler, functional auxiliary agent, and optional pigment to obtain a mixed material;

[0028] Mix the mixture with the catalyst for a second time to obtain a one-component thermally conductive silicone gel.

[0029] In some embodiments of the present invention, the second mixing is carried out under vacuum conditions, and the temperature of the second mixing is 120-170 °C.

[0030] Optionally, the method further includes: packaging the one-component thermally conductive silicone gel.

[0031] Additional aspects and advantages of the present invention will be given in part in the following description, will become apparent in part from the following description, or will be learned through the practice of the present invention. Detailed Embodiments

[0032] The embodiments of the present invention will be described in detail below. The embodiments described below are exemplary and are only used to explain the present invention and should not be construed as limiting the present invention.

[0033] The "range" disclosed in the present invention is defined in the form of a lower limit and / or an upper limit. A given range is defined by selecting a lower limit and / or an upper limit. The ranges defined in this way may or may not include the end values, and can be combined arbitrarily, that is, any lower limit can be combined with any upper limit to form a range not explicitly recorded, and any lower limit can be combined with other lower limits to form a range not explicitly recorded. Similarly, any upper limit can be combined with any other upper limit to form a range not explicitly recorded. In addition, each individually disclosed point or single value itself can be used as a lower limit or an upper limit and combined with any other point or single value or combined with other lower limits or upper limits to form a range not explicitly recorded.

[0034] In the present invention, the expressions "first" and "second" are only used for the purpose of facilitating distinction and description, and have no special meaning, and should not be construed as indicating or implying relative importance or implicitly indicating the quantity of the indicated technical features.

[0035] If there is no special instruction, all embodiments and optional embodiments of the present invention can be combined with each other to form a new technical solution, and such a technical solution should be considered to be included in the disclosure of the present invention.

[0036] The first aspect of the present invention provides a one-component thermally conductive silicone gel. The one-component thermally conductive silicone gel includes: hydrogen-containing silicone oil, 20-50 parts by weight of vinyl silicone oil, 500-2000 parts by weight of thermally conductive filler, 1-100 parts by weight of functional auxiliary agent, 1-4 parts by weight of catalyst, and 0-8 parts by weight of pigment.

[0037] In the present invention, as the base polymer in the one-component thermally conductive silicone gel, the vinyl silicone oil can be a conventional choice in addition-curable silicone rubber. According to some embodiments, the vinyl silicone oil can be selected from at least one of vinyl-terminated polydimethylsiloxane (e.g., mono-end vinyl-terminated polydimethylsiloxane, di-end vinyl-terminated polydimethylsiloxane), polymethylphenyl-methylvinylsiloxane, and methyl-terminated polysiloxane with vinyl groups in the side chain (e.g., trimethyl-terminated vinylmethylpolysiloxane).

[0038] In the present invention, the vinyl content in the vinyl silicone oil can be 0.1 - 0.5 mmol / g, such as 0.1 mmol / g, 0.16 mmol / g, 0.20 mmol / g, 0.22 mmol / g, 0.25 mmol / g, 0.28 mmol / g, 0.30 mmol / g, 0.35 mmol / g, 0.39 mmol / g, 0.40 mmol / g, 0.42 mmol / g, 0.45 mmol / g, etc.; the viscosity of the vinyl silicone oil at 25 °C is 10 - 600 mPa·s, such as 20 mPa·s, 50 mPa·s, 100 mPa·s, 115 mPa·s, 130 mPa·s, 200 mPa·s, 250 mPa·s, 300 mPa·s, 500 mPa·s, 520 mPa·s, etc. or any range between any two of them. In the one-component thermally conductive silicone gel, by weight, the vinyl silicone oil can be, for example, 20 parts, 30 parts, 35 parts, 40 parts, 45 parts, 50 parts, etc. As a specific example, the vinyl silicone oil is 50 parts by weight.

[0039] In the present invention, as the crosslinking agent in the one-component thermally conductive silicone gel, the present invention places no particular limitation on the hydrogen-containing silicone oil, as long as it can undergo a hydrosilylation reaction with vinyl silicone oil under the action of the catalyst. According to the following embodiments, the hydrogen-containing silicone oil is terminal hydrogen-containing silicone oil and / or side hydrogen-containing silicone oil. Generally, the viscosity of the hydrogen-containing silicone oil at 25°C can be 10 to 300 cSt, such as 10 cSt, 20 cSt, 30 cSt, 35 cSt, 40 cSt, 50 cSt, 60 cSt, 80 cSt, 100 cSt, 130 cSt, 150 cSt, 200 cSt, 220 cSt, etc. or any range between any two of them; the Si-H content can be 0.5 to 12 mmol / g, such as 0.5 mmol / g, 0.6 mmol / g, 0.7 mmol / g, 0.8 mmol / g, 0.9 mmol / g, 1.0 mmol / g, 1.2 mmol / g, 1.5 mmol / g, 1.7 mmol / g, 1.8 mmol / g, 2.0 mmol / g, 2.2 mmol / g, 2.7 mmol / g, 3 mmol / g, 6 mmol / g, 7 mmol / g, 8 mmol / g, etc.

[0040] As a preferred embodiment, the hydrogen-containing silicone oil is selected from terminal hydrogen-containing polydimethylsiloxane and side hydrogen-containing polydimethylsiloxane. More preferably, the Si-H content of the terminal hydrogen-containing polydimethylsiloxane is 0.5 to 12 mmol / g, and the viscosity at 25°C is 30 to 50 cSt; the Si-H content of the side hydrogen-containing polydimethylsiloxane is 0.5 to 7 mmol / g, and the viscosity at 25°C is 10 to 300 cSt, such as 20 to 30 cSt, 30 to 40 cSt, 50 to 60 cSt, etc.

[0041] In the present invention, the mass ratio of the hydrogen-containing silicone oil to the vinyl silicone oil is (0.2 to 5):100, such as 0.2:100, 0.5:100, 0.7:100, 1:100, 2:100, 3:100, 4:100, 5:100, etc.

[0042] In some embodiments, the molar ratio of the hydrogen groups in the hydrogen-containing silicone oil to the vinyl groups in the vinyl silicone oil can be (0.1 to 0.5):1, such as 0.1:1, 0.15:1, 0.17:1, 0.20:1, 0.23:1, 0.25:1, 0.3:1, 0.4:1, 0.5:1, etc., and preferably (0.1 to 0.3):1.

[0043] In the present invention, the heat-conducting filler may be selected from one or more of metal fillers, carbon materials, and inorganic non-metallic fillers. Among them, specific examples of the metal filler include, but are not limited to, silver powder, copper powder, aluminum powder, and copper nanowires; specific examples of the carbon material include, but are not limited to, graphene, carbon nanotubes, graphite microflakes, expanded graphite, and diamond; specific examples of the inorganic non-metallic filler include, but are not limited to, aluminum nitride, boron nitride, aluminum oxide, zinc oxide, magnesium oxide, aluminum hydroxide, and silica powder. To further improve the heat-conducting performance, preferably, the heat-conducting filler is selected from at least two of aluminum nitride, aluminum oxide, magnesium oxide, boron nitride, silicon carbide, zinc oxide, aluminum hydroxide, and silica powder. In addition, the surface of the heat-conducting filler usually includes hydroxyl groups (for example, powders such as aluminum oxide, zinc oxide, and nitrides are prone to absorb water and react due to surface structure defects and unsaturated sites, and factors such as the preparation process and storage environment are also likely to introduce hydroxyl groups on the surface of the powder). In the single-component heat-conducting silicone gel, by weight, the heat-conducting filler may be, for example, 700 parts, 800 parts, 1000 parts, 1500 parts, 1800 parts, 1850 parts, 1900 parts, 1950 parts, 2000 parts, etc.

[0044] In the present invention, the heat-conducting filler is preferably spherical or quasi-spherical heat-conducting particles with a particle size of 0.1 to 90 μm. More preferably, based on the total weight of each heat-conducting filler, 10 to 25% of each heat-conducting filler has a particle size D50 of 0.1 to 3 μm, such as 10%, 15%, 20%, 25%, etc.; 10 to 30% has a particle size D50 of 5 to 15 μm, such as 10%, 15%, 20%, 25%, etc.; and 45% to 70% has a particle size D50 of 40 to 90 μm, such as 45%, 50%, 55%, 60%, 65%, etc. By compounding heat-conducting fillers with different particle sizes, dense packing can be achieved between the powders, the heat-conducting transmission path can be optimized, and the heat-conducting performance of the gel can be effectively improved.

[0045] In the present invention, the catalyst may be selected from various existing catalysts commonly used in addition-cured liquid silicone rubber, such as various platinum catalysts. According to some embodiments, the platinum catalyst is one or more of chloroplatinic acid, platinum-vinylsiloxane complex, and platinum-alkynyl chelate. Among them, the platinum-vinylsiloxane complex may be, for example, 1,3-divinyl-1,1,3,3-tetramethyldisiloxane platinum complex (CAS: 68478-92-2), and the platinum-alkynyl chelate may be, for example, bis(alkyne)bis(triphenylphosphine)platinum complex, bis(alkyne)cyclodienyl platinum complex, Pincer-type platinum-alkynyl complex, etc. In the single-component heat-conducting silicone gel, by weight, the catalyst may be, for example, 1 part, 2 parts, 2.5 parts, 3 parts, 4 parts, etc. In addition, the platinum catalyst used to prepare the functional auxiliary may also be selected from the catalysts listed above.

[0046] In the present invention, in the single-component thermal conductive silicone gel, by weight, the functional aid can be, for example, 10 parts, 20 parts, 25 parts, 30 parts, 35 parts, 40 parts, 50 parts, 70 parts, 90 parts, etc.

[0047] In the present invention, the functional aid is an alkoxy-terminated polysiloxane having the structure shown in Formula 1:

[0048]

[0049] Wherein, each R1, each R2 and each R3 are the same or different from each other, and are independently selected from alkyl groups having 1 to 5 carbon atoms; each L1 and each L2 are the same or different from each other, and are independently selected from a single bond or an alkylene group having 1 to 5 carbon atoms; m and n represent the degree of polymerization.

[0050] In the present invention, the alkyl group having 1 to 5 carbon atoms may include a straight-chain alkyl group having 1 to 5 carbon atoms and a branched-chain alkyl group having 3 to 5 carbon atoms. Specific examples of the alkyl group include, but are not limited to, methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, n-pentyl, etc. The alkylene group having 1 to 5 carbon atoms is a divalent group formed by further removing one hydrogen atom from the alkyl group having 1 to 5 carbon atoms. It can be understood that a single bond means a direct connection between the two groups it associates with.

[0051] In some embodiments, each R1, each R2 and each R3 are independently selected from methyl (-CH3) or ethyl (-CH2CH3); each L1 and each L2 are independently selected from a single bond, methylene (-CH2-) or ethylene (-CH2CH2-), preferably a single bond or methylene.

[0052] In the present invention, m and n respectively represent the degree of polymerization. m and n are related to the viscosity of the alkoxy-terminated polysiloxane, and generally increase with the increase of viscosity. According to some embodiments, m is 10 to 100, and n is 10 to 50.

[0053] As a preferred embodiment, the alkoxy-terminated polysiloxane has the structure shown in Formula 1-1:

[0054]

[0055] In the structure shown in Formula 1-1, both ends of the polysiloxane main chain are terminated by trimethoxy groups. The trimethoxy groups provided by Formula 1-1 undergo a dehydration condensation reaction with the hydroxyl groups on the surface of the thermal conductive filler, and the vinyl groups provided by the side chains can undergo an addition reaction with the hydrogen-containing silicone oil, effectively improving the compatibility between the thermal conductive filler and the silicone oil.

[0056] In some embodiments, the alkoxy-terminated polysiloxane has a viscosity of 20 to 100 cSt at 25°C, such as 20 cSt, 22 cSt, 25 cSt, 30 cSt, 33 cSt, 37 cSt, 40 cSt, 45 cSt, 50 cSt, 55 cSt, 60 cSt, 70 cSt, 80 cSt, 90 cSt, 95 cSt, etc. If the viscosity is too low, it may be disadvantageous for improving the adhesion strength. If the viscosity is too high, it may affect the workability of the system. Additionally, the vinyl content in the alkoxy-terminated polysiloxane can be 0.1 to 0.5 mmol / g, such as 0.15 mmol / g, 0.2 mmol / g, 0.3 mmol / g, 0.4 mmol / g, etc. The vinyl content can be measured by near-infrared spectroscopy.

[0057] In the present invention, the functional auxiliary can be prepared by a method including the following steps: in the presence of a platinum catalyst, in an inert atmosphere protection (such as nitrogen, argon), subject the reactants to a hydrosilylation reaction, wherein the reactants are composed of a hydrogen-containing silicone oil with hydrogen at the end side shown by formula a, a monoalkenyl alkoxysilicone oil shown by formula b, and a diene-based disiloxane shown by formula c:

[0058]

[0059]

[0060] In formulas a to c, the definitions of R1, R2, R3, L1, L2, m, and n are the same as the definitions of the corresponding symbols in formula 1, and will not be elaborated herein.

[0061] In the reactants, specific examples of the monoalkenyl alkoxysilicone oil include but are not limited to vinyltrimethoxysilane and allyltrimethoxysilane; specific examples of the diene-based disiloxane include but are not limited to tetramethyldivinyldisiloxane and diallyltetramethyldisiloxane.

[0062] In the reactants, the molar ratio of the monoalkenyl alkoxysilicone oil to the diene-based disiloxane can be 1∶(1 - 10), such as 1∶2, 1∶4, 1∶5, 1∶7, 1∶8, 1∶9, 1∶10, etc.

[0063] Among the reactants, the hydrogen content of the terminal hydrogen-containing silicone oil can be 0.2-1.5 wt%, such as 0.22%, 0.25%, 0.5%, 0.6%, 0.8%, 0.82%, etc., and the viscosity at 25 °C can be 15-100 cSt, such as 15 cSt, 30 cSt, 35 cSt, 40 cSt, 50 cSt, 60 cSt, 70 cSt, 80 cSt, 90 cSt, etc. The terminal hydrogen-containing silicone oil can be prepared by methods well-known in the art or obtained by commercial purchase. For example, it can be the terminal hydrogen-containing silicone oil products of Zhejiang Runhe New Materials Co., Ltd. (abbreviation "Runhe Materials") with the grades of RH-LHC-1 (hydrogen content about 0.60 wt%), RH-LHC-2 (hydrogen content about 0.80 wt%), RH-LHC-3 (hydrogen content about 0.80 wt%), RH-LHC-7 (hydrogen content about 0.25 wt%), etc.

[0064] Among the reactants, the relative dosage of the total of the monoalkenylalkoxysilicone oil and the diene-based disiloxane to the terminal hydrogen-containing silicone oil can be 1:(0.8-2) in terms of the molar ratio of vinyl and hydrogen groups, such as 1:0.8, 1:0.9, 1:1, 1:1.1, 1:1.2, 1:1.5, 1:2, etc.

[0065] In some embodiments, the mass dosage of the platinum catalyst accounts for 5-20 ppm relative to the total mass of the reactants, such as 5 ppm, 10 ppm, 12 ppm, 18 ppm, etc.

[0066] In some embodiments, the hydrosilylation reaction is carried out under stirring conditions. The reaction temperature can be 90-130 °C, such as 95 °C, 100 °C, 105 °C, 110 °C, 120 °C, 125 °C, 130 °C, and the reaction time can be 1-5 h, such as 1 h, 1.5 h, 2 h, 2.5 h, 3 h, 4 h, etc. In addition, the stirring speed can be controlled at 200-500 rpm.

[0067] As a preferred example, the functional additive is prepared according to the following method:

[0068] (a) Under nitrogen protection, the terminal hydrogen-containing silicone oil and the monoalkenylalkoxysilicone oil are stirred evenly, and then the platinum catalyst is added. After stirring for 10-40 min, the temperature is raised to 100-120 °C, and the reaction is stirred for 0.5-2 h;

[0069] (b) The reaction system obtained in step (a) is cooled to room temperature, tetramethyldivinyldisiloxane is added, and the temperature is raised to 100-120 °C again, and the reaction is stirred for 0.5-2 h. After the reaction is completed, the obtained system is cooled to room temperature and subjected to vacuum distillation to obtain an alkoxy-terminated polysiloxane.

[0070] In the present invention, the one-component thermally conductive silicone gel may or may not contain a pigment, which can be specifically selected according to the application scenario of the thermally conductive gel. According to some embodiments, the pigment is selected from at least one of carbon black, iron red, cobalt blue, and cadmium yellow. In the one-component thermally conductive silicone gel, by weight, the pigment can be, for example, 1 part, 2 parts, 3 parts, 4 parts, 5 parts, 7 parts, 8 parts, etc.

[0071] The second aspect of the present invention provides a method for preparing the one-component thermally conductive silicone gel described in the first aspect of the present invention, including the following steps S1 to S2.

[0072] S1: Perform a first mixing on the vinyl silicone oil, crosslinking agent, thermally conductive filler, functional auxiliary agent, and optionally the pigment to obtain a mixed material. Among them, the first mixing can be carried out at 20 to 40 °C (for example, room temperature).

[0073] S2: Perform a second mixing on the mixed material and the catalyst to obtain a one-component thermally conductive silicone gel. Among them, the second mixing is preferably carried out under vacuum conditions and at high temperature. Preferably, the temperature of the second mixing is 120 to 170 °C, such as 120 °C, 130 °C, 140 °C, 145 °C, 150 °C, 160 °C, etc., and the pressure (gauge pressure) can be -0.05 to -0.1 MPa.

[0074] In the method of the present invention, there is no particular limitation on the equipment used for mixing, as long as it can evenly disperse each material. For example, it can be a planetary stirrer.

[0075] Optionally, the method of the present invention further includes step S3.

[0076] S3: Package the one-component thermally conductive silicone gel obtained in step S2. For example, the one-component thermally conductive silicone gel can be packaged into single-component tubes. The capacity of the single-component tube can be 1 to 100 CC, such as 10 CC, 30 CC, 50 CC, etc.

[0077] The following describes the embodiments of the present invention. The embodiments described below are exemplary and are only used to explain the present invention and should not be construed as a limitation to the present invention.

[0078] The following Preparation Examples 1 to 4 are used to illustrate the alkoxy-terminated polysiloxane (with the structure shown in Formula 1-1) and its preparation method used in the following embodiments. Among them, the hydrogen-containing silicone oil at the end side is RH-LHC-2, RH-LHC-3, and RH-LHC-7 of Runhe Materials; the platinum catalyst is platinum-vinylsiloxane, specifically the product with the brand PC-12 of Shanghai Neutron Star Chemical Technology Co., Ltd.

[0079] Preparation Example 1

[0080] In this preparation example, among the reactants used, the total amount of vinyltrimethoxysilane and tetramethyldivinyldisiloxane and the amount of the terminal hydrogen-containing silicone oil RH-LHC-3 are in a ratio of 1:1 in terms of the molar ratio of vinyl and hydrogen groups, and the molar ratio of vinyltrimethoxysilane to tetramethyldivinyldisiloxane is 1:5. Based on the total weight of the reactants, the dosage of the platinum catalyst is 10 ppm.

[0081] The specific preparation method is as follows:

[0082] (a) Under nitrogen protection, RH-LHC-3 and vinyltrimethoxysilane are stirred evenly, and then the platinum catalyst is added. After stirring for 30 min, the temperature is raised to 100 °C, and stirring reaction is carried out for 1 h;

[0083] (b) The reaction system obtained in step (a) is cooled to room temperature, tetramethyldivinyldisiloxane is added, the temperature is continuously raised to 120 °C, and stirring reaction is carried out for 1 h. After the reaction ends, the obtained system is cooled to room temperature and subjected to vacuum distillation to obtain alkoxy-terminated polysiloxane, denoted as auxiliary A1.

[0084] The vinyl content in auxiliary A1 is 0.4 mmol / g, and the viscosity at 25 °C is 40 cSt.

[0085] Preparation Example 2

[0086] The preparation method refers to Preparation Example 1, the difference is that RH-LHC-3 is replaced by RH-LHC-7. In this preparation example, among the reactants used, the total amount of vinyltrimethoxysilane and tetramethyldivinyldisiloxane and the amount of the terminal hydrogen-containing silicone oil RH-LHC-7 are in a ratio of 1:1 in terms of the molar ratio of vinyl and hydrogen groups, and the molar ratio of vinyltrimethoxysilane to tetramethyldivinyldisiloxane is 1:5; based on the total weight of the reactants, the dosage of the platinum catalyst is 10 ppm.

[0087] The prepared alkoxy-terminated polysiloxane is denoted as auxiliary A2. The vinyl content of auxiliary A2 is 0.3 mmol / g, and the viscosity at 25 °C is 55 cSt.

[0088] Preparation Example 3

[0089] The preparation method was referred to Preparation Example 1, except that RH-LHC-3 was replaced by RH-LHC-2. In this preparation example, among the reactants used, the molar ratio of the total amount of vinyltrimethoxysilane and tetramethyldivinyldisiloxane to the amount of terminal hydrogen-containing silicone oil RH-LHC-2 was 1:1 based on the molar ratio of vinyl and hydrogen groups, and the molar ratio of vinyltrimethoxysilane to tetramethyldivinyldisiloxane was 1:5; based on the total weight of the reactants, the dosage of platinum catalyst was 10 ppm. The alkoxy-terminated polysiloxane prepared was denoted as Auxiliary A3, and the vinyl content of Auxiliary A3 was 0.2 mmol / g, and the viscosity at 25 °C was 80 cSt.

[0090] Preparation Example 4

[0091] The preparation method was referred to Preparation Example 1, except that the amounts of reactants were adjusted so that the molar ratio of the total amount of vinyltrimethoxysilane and tetramethyldivinyldisiloxane to the amount of terminal hydrogen-containing silicone oil RH-LHC-3 was 1:2 based on the molar ratio of vinyl and hydrogen groups. The alkoxy-terminated polysiloxane prepared was denoted as Auxiliary A4, and the vinyl content of Auxiliary A4 was 0.15 mmol / g, and the viscosity at 25 °C was 20 cSt.

[0092] In the following examples and comparative examples, unless otherwise specified, all parts are by weight.

[0093] The vinyl silicone oil used was vinyl-terminated polydimethylsiloxane, specifically the product with the brand name RH-Vi1325 of Runhe Materials (the viscosity at 25 °C was 250 mPa·s, and the vinyl content was 0.22 mmol / g);

[0094] The crosslinking agent was composed of hydrogen-containing silicone oil I and hydrogen-containing silicone oil II in a mass ratio of 1:1; among them,

[0095] The hydrogen-containing silicone oil I was terminal hydrogen-containing polydimethylsiloxane, specifically the product with the brand name RH-DH07 of Runhe Materials (the viscosity at 25 °C was 30-50 cSt, and the Si-H content was 0.7 mmol / g);

[0096] The hydrogen-containing silicone oil II was side hydrogen-containing polydimethylsiloxane, specifically the product with the brand name RH-H33 of Runhe Materials (the viscosity at 25 °C was 60-80 cSt, and the Si-H content was 1.8 mmol / g);

[0097] The catalyst was platinum catalyst PC-12; the pigment was cobalt blue;

[0098] The alumina was purchased from BaiTu Company, with grades BAK-70, BAK-10, and BAK-5; the zinc oxide was purchased from Jinge New Materials Company, with grade GD-S003A. The thermal conductive filler consists of alumina and zinc oxide: Alumina (with a mass ratio of BAK-70, BAK-10, and BAK-5 of 5 / 2 / 1) and zinc oxide were mixed evenly according to a mass ratio of 8 / 2 to obtain the thermal conductive filler. Among them, 50% of the total mass of the thermal conductive filler has a D50 of 70 - 75 μm, 30% of the total mass has a particle size D50 of 5 - 10 μm, and 20% of the total mass has a particle size D50 of 0.3 - 1.5 μm.

[0099] Example 1

[0100] 50 parts of vinyl silicone oil, 2 parts of crosslinking agent, 1900 parts of thermal conductive filler, 4 parts of pigment, and 30 parts of Auxiliary A1 were added to a planetary mixer and stirred at room temperature for 1 h to make the components mix evenly. Then, 4 parts of catalyst were added, the temperature was raised to 150 °C, and after evacuating to -0.1 MPa (gauge pressure), stirring was continued for 2 h. The resulting product was cooled to room temperature to obtain a one-component thermal conductive silicone gel, denoted as B1.

[0101] Example 2

[0102] 50 parts of vinyl silicone oil, 2 parts of crosslinking agent, 1900 parts of thermal conductive filler, 4 parts of pigment, and 30 parts of Auxiliary A2 were added to a planetary mixer and stirred at room temperature for 1 h to make the components mix evenly. Then, 4 parts of catalyst were added, the temperature was raised to 150 °C, and after evacuating to -0.1 MPa (gauge pressure), stirring was continued for 2 h. The resulting product was cooled to room temperature to obtain a one-component thermal conductive silicone gel, denoted as B2.

[0103] Example 3

[0104] 50 parts of vinyl silicone oil, 2 parts of crosslinking agent, 1900 parts of thermal conductive filler, 4 parts of pigment, and 30 parts of Auxiliary A3 were added to a planetary mixer and stirred at room temperature for 1 h to make the components mix evenly. Then, 4 parts of catalyst were added, the temperature was raised to 150 °C, and after evacuating to -0.1 MPa (gauge pressure), stirring was continued for 2 h. The resulting product was cooled to room temperature to obtain a one-component thermal conductive silicone gel, denoted as B3.

[0105] Example 4

[0106] 50 parts of vinyl silicone oil, 2 parts of crosslinking agent, 1900 parts of thermal conductive filler, 4 parts of pigment, and 30 parts of Auxiliary A4 were added to a planetary mixer and stirred at room temperature for 1 h to make the components mix evenly. Then, 4 parts of catalyst were added, the temperature was raised to 150 °C, and after evacuating to -0.1 MPa (gauge pressure), stirring was continued for 2 h. The resulting product was cooled to room temperature to obtain a one-component thermal conductive silicone gel, denoted as B4.

[0107] Example 5

[0108] 50 parts of vinyl silicone oil, 1.5 parts of crosslinking agent, 1900 parts of thermal conductive filler, 4 parts of pigment and 40 parts of auxiliary agent A1 were added into a planetary mixer and stirred at room temperature for 1 hour to mix the components evenly. Then 4 parts of catalyst were added, the temperature was raised to 150°C, and the mixture was evacuated to -0.1 MPa (gauge pressure). The mixture was stirred for 2 hours. The obtained product was cooled to room temperature to obtain a single-component thermal conductive silicone gel, which was recorded as B5.

[0109] Comparative Example 1

[0110] A single-component thermally conductive silicone gel was prepared according to the method of Example 1, except that the auxiliary agent A1 was replaced with an equal mass of a silane coupling agent (dodecyltrimethoxysilane). The prepared single-component thermally conductive silicone gel was recorded as D1.

[0111] Comparative Example 2

[0112] The one-component thermally conductive silicone gel was prepared according to the method of Example 1, except that the auxiliary agent A1 was not added. As a result, during the preparation of the thermally conductive silicone gel, the thermally conductive filler and the silicone oil could not be evenly dispersed.

[0113] Test Case

[0114] The test example is used to illustrate the application performance of the single-component thermally conductive silicone gels B1 to B5 and D1 prepared in the above examples and comparative examples. Before use, the thermally conductive gels were respectively packed into 30CC single-component tubes for standby use.

[0115] (1) Thermal conductivity: According to ASTM D5470, the thermal conductivity of the sample was tested using a thermal conductivity meter (model Longwin TIM LW-9389). The test pressure was 40 psi, the heating temperature was 80°C, and the duration was 8 min. Based on the samples with different thicknesses L (specifications 26 mm × 26 mm × L, L = 0.5 mm, 1 mm, 1.5 mm), the total thermal resistance-thickness curve was drawn and a straight line was fitted to calculate the thermal conductivity.

[0116] (2) Oil separation performance test: Weigh 2.0g of a single-component thermal conductive silicone gel sample and place it evenly on filter paper. Use a glass sheet to press it into a thickness of 1mm. Use a 2cm diameter cutter to cut out a circle. Place it in a 150℃ oven for 24h and observe the diffusion distance of the circle (calculated from the circumference of the circle and record the maximum diffusion distance). The longer the diffusion distance, the higher the oil separation performance.

[0117] (3) Extrusion performance test: Using a dispensing needle with a diameter of 2.54 mm (0.1 inch), the quality of the thermal conductive gel extruded through the needle within 1 minute was measured under a constant air pressure of 90 psi (about 621 kPa).

[0118] In addition, the corresponding performance tests were carried out using the existing similar products on the market (Thermal Gel GEL45 of Parker Chomerics) as comparative samples. The results of the above performance tests are shown in Table 1.

[0119] Table 1

[0120]

[0121] As can be seen from Table 1, compared with the existing similar product GEL45, the thermal gels B1 to B5 provided in Examples 1 to 5 have higher extrusion quality and lower oil bleeding while maintaining a relatively high thermal conductivity. In addition, by comparing Examples 1 to 5 with Comparative Example 1, it can be seen that compared with the use of conventional long-chain silane coupling agents, the use of the functional auxiliary agent with the structure shown in Formula 1 can effectively improve the compatibility between the thermal conductive filler and silicone oil and the fluidity of the thermal gel, making the thermal gels B1 to B5 exhibit excellent extrusion performance and lower oil bleeding, while also having relatively high thermal conductivity.

[0122] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and are not intended to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that they can still modify the technical solutions described in the foregoing embodiments, or perform equivalent replacements on some or all of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the scope of the technical solutions of the embodiments of the present invention, and they should all be covered by the scope of the claims and the description of the present invention. In particular, as long as there is no structural conflict, the technical features mentioned in each embodiment can be combined in any way. The present invention is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.

Claims

1. A one-component thermally conductive silicone gel, characterized in that, Comprising: 20 - 50 parts by weight of vinyl silicone oil, hydrogen-containing silicone oil, 500 - 2000 parts by weight of heat-conducting filler, 1 - 100 parts by weight of functional additive, 1 - 4 parts by weight of catalyst, and 0 - 8 parts by weight of pigment; and the mass ratio of the hydrogen-containing silicone oil to the vinyl silicone oil is (0.2 - 5)∶100; The functional additive is an alkoxy-terminated polysiloxane having a structure as shown in Formula 1: Wherein, each R1, each R2, and each R3 are the same or different from each other, and are each independently selected from alkyl groups having 1 - 5 carbon atoms; each L1 and each L2 are the same or different from each other, and are each independently selected from a single bond or an alkylene group having 1 - 5 carbon atoms; m and n represent the degree of polymerization.

2. The one-component thermally conductive silicone gel according to claim 1, wherein The hydrogen-containing silicone oil is terminal hydrogen-containing silicone oil and / or side hydrogen-containing silicone oil; Preferably, in the single-component heat-conducting silicone gel, the molar ratio of the hydrogen groups in the hydrogen-containing silicone oil to the vinyl groups in the vinyl silicone oil is (0.1 - 0.5)∶1.

3. The one-component thermally conductive silicone gel according to claim 1 or 2, wherein The vinyl silicone oil is selected from at least one of vinyl-terminated polydimethylsiloxane, polymethylphenyl-methylvinylsiloxane, and methyl-terminated and side-chain vinyl-containing polysiloxane; Preferably, the vinyl content in the vinyl silicone oil is 0.1 - 0.5 mmol / g, and the viscosity at 25°C is 10 - 600 mPa·s.

4. The one-component thermally conductive silicone gel according to any one of claims 1-3, characterized in that In Formula 1, each R1, each R2, and each R3 are each independently selected from methyl or ethyl, and each L1 and each L2 are each independently selected from a single bond, methylene, or ethylene; Preferably, m is 10 - 100, and n is 10 - 50; Preferably, the viscosity of the alkoxy-terminated polysiloxane at 25°C is 20 - 100 cSt.

5. The one-component thermally conductive silicone gel according to claim 4, characterized in that, The functional additive is prepared by a method including the following steps: in the presence of a platinum catalyst, under the protection of an inert atmosphere, subjecting the reactants to a hydrosilylation reaction, wherein the reactants are composed of a terminal and side hydrogen-containing silicone oil shown in Formula a, a monoalkenyl alkoxysilicone oil shown in Formula b, and a diene-based disiloxane shown in Formula c: Preferably, relative to the total mass of the reactants, the mass dosage of the platinum catalyst accounts for 5 - 20 ppm; in the reactants, the sum of the monoalkenyl alkoxysilicone oil and the diene-based disiloxane and the relative dosage of the terminal and side hydrogen-containing silicone oil are in a molar ratio of vinyl to hydrogen groups of 1∶(0.8 - 2); Preferably, the molar ratio of the monoalkenyl alkoxysilicone oil to the diene-based disiloxane is 1∶(1 - 10); Preferably, the hydrosilylation reaction is carried out under stirring conditions, the reaction temperature is 90 - 130°C, and the reaction time is 1 - 5 h.

6. The one-component thermally conductive silicone gel according to any one of claims 1-5, characterized in that The heat-conducting filler is selected from at least one of metal fillers, carbon materials, and inorganic non-metallic fillers; Preferably, the heat-conducting filler is selected from at least two of diamond, aluminum nitride, alumina, magnesia, boron nitride, silicon carbide, zinc oxide, aluminum hydroxide, and silica powder; Preferably, based on the total weight of the heat-conducting filler, the proportion of the heat-conducting filler with a particle size D50 of 0.1 - 3 μm is 10% - 25%, the proportion of the heat-conducting filler with a particle size D50 of 5 - 15 μm is 10% - 30%, and the proportion of the heat-conducting filler with a particle size D50 of 40 - 90 μm is 45% - 70%.

7. The one-component thermally conductive silicone gel according to any one of claims 1-6, characterized in that, The catalyst is selected from at least one of chloroplatinic acid, platinum-vinylsiloxane complex and platinum-alkynyl chelate.

8. The one-component thermally conductive silicone gel according to any one of claims 1-7, characterized in that, The pigment is selected from at least one of carbon black, iron oxide red, cobalt blue and cadmium yellow.

9. A method for preparing the one-component thermally conductive silicone gel according to any one of claims 1-8, characterized in that, It includes the following steps: Carry out a first mixing on the vinyl silicone oil, hydrogen-containing silicone oil, heat-conducting filler, functional additive and optionally the pigment to obtain a mixed material. Carry out a second mixing on the mixed material and the catalyst to obtain a one-component heat-conducting silicone gel.

10. The method according to claim 9, wherein The second mixing is carried out under vacuum conditions, and the temperature of the second mixing is 120-170 °C.

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