High-strength substrate-free heat-conducting insulating sheet and preparation method thereof

Abstract

The invention belongs to the field of heat-conducting materials, and particularly relates to a high-strength base-material-free heat-conducting insulating sheet and a preparation method thereof. The high-strength base-material-free heat-conducting insulating sheet is prepared from, by mass, 10-30 parts of organic silicone oil, 110-400 parts of heat-conducting filler and 0.2-0.7 part of dispersing agent, the heat-conducting filler is spherical heat-conducting filler and spheroidal heat-conducting filler, and the mass ratio of the spherical heat-conducting filler to the spheroidal heat-conducting filler is (40-60): (120-150). The organic silicone oil comprises vinyl silicone oil, the viscosity of the vinyl silicone oil at the temperature of 25 DEG C is 30-1000000 mPa.S, and the content of vinyl is 0.01-6%; the preparation of the product does not need a base material, the heat conductivity coefficient of the heat-conducting insulation sheet is greater than 3W / m.k, the breakdown voltage is not less than 7KV, the tensile strength is greater than 3MPa, and the heat dissipation and insulation effects are excellent.

Description

Technical Field

[0001] The invention belongs to the field of heat-conducting materials, and more specifically relates to a high-strength substrate-free heat-conducting insulating sheet and a preparation method thereof. Background Art

[0002] With the advancement of science and technology and the development of productivity, consumers have an increasing demand for the refinement and convenience of digital products. At present, the mainstream digital products on the market are still powered by electricity. However, electric drive will inevitably lead to considerable heat loss during the normal operation of the product. Since the internal components of digital products are very sensitive to heat energy, if the heat cannot be dissipated in time, the product performance may be weakened due to the excessive temperature inside the device, and even spontaneous combustion may occur, posing a great safety hazard. Therefore, it is very important to export the heat inside the device in time for the normal operation of digital products and reduce the safety risks of users. The current common treatment method is to select a suitable thermal conductive material between the heat source and the radiator interlayer of the digital product as a conductive medium to conduct and dissipate the heat generated by the electrical energy.

[0003] Thermally conductive materials used in high-precision electronic devices not only need to have excellent thermal conductivity, but also good electrical properties. When the voltage on both sides of the insulator inside the electronic device is higher, the electric field force on the insulator is also higher, which will cause ionization collision, leading to the breakdown of the insulator, bringing great safety hazards. Therefore, a thermally conductive material that can withstand high breakdown voltage is urgently needed.

[0004] Thermally conductive insulating sheets are mainly used for the transfer interface between electronic equipment and heat sinks or product housings. Due to the high reliability, insulation, low contact thermal resistance, and high thermal conductivity of thermally conductive insulating sheets, they are widely used in communication equipment, computers, and household appliances. The biggest feature of thermally conductive insulating sheets is that they are thin. The thickness is usually 0.05-0.5mm, and they can be used in high-precision equipment. However, if the material is too thin, it will work under long-term overheating conditions, or as the material ages and deteriorates, it will significantly affect the mechanical strength and normal working performance of the thermally conductive insulating sheet. At present, conventional thermally conductive insulating sheets on the market require a substrate to ensure mechanical strength. Usually, glass fiber cloth and polyimide film are used as the substrate. For example, the thermally conductive silicone cloth disclosed in CN206170755U uses glass fiber cloth as the substrate. However, the price of some substrate products is relatively high, which increases the production cost, and the production process is also relatively complicated. For example, thermal conductive products with glass fiber cloth as the base material can only produce products with low thermal conductivity coefficient and cannot solve the heat dissipation problem well. At the same time, the production process of glass fiber cloth is also relatively complicated. Although the production process of polyimide base material is relatively simple, and the thermal conductivity and mechanical properties are relatively better, the price is very expensive and cannot be used in conventional products.

[0005] Therefore, how to provide a thermally conductive insulating sheet that takes into account low-cost production, low thermal resistance, high insulation, high strength, and no substrate is a technical problem that urgently needs to be solved. Summary of the invention

[0006] In order to solve the above technical problems, the first aspect of the present invention provides a high-strength substrate-free thermally conductive insulating sheet, the raw materials for its preparation include, by weight, 10-30 parts of silicone oil, 110-400 parts of thermally conductive filler, and 0.2-0.7 parts of dispersant. The thermal conductivity of the thermally conductive insulating sheet is greater than 3W / m·k, and the tensile strength is greater than 3MPa.

[0007] Furthermore, the raw materials for preparing the high-strength substrate-free thermally conductive insulating sheet include, by weight, 12-20 parts of silicone oil, 170-210 parts of thermally conductive filler, and 0.3-0.7 parts of dispersant.

[0008] As an implementable case, the organic silicone oil includes vinyl silicone oil.

[0009] Furthermore, the viscosity of the vinyl silicone oil at 25° C. is 30-1,000,000 mPa·S. Furthermore, the viscosity of the vinyl silicone oil at 25° C. is 10,000-100,000 mPa·S.

[0010] Furthermore, the vinyl content in the vinyl silicone oil is 0.01-6%.

[0011] Furthermore, the vinyl content in the vinyl silicone oil is 0.3-0.45%.

[0012] Vinyl silicone oil has a certain thermal conductivity due to its molecular structure characteristics. Adding an appropriate amount of vinyl silicone oil to the thermally conductive insulating sheet can effectively improve the thermal conductivity of the material, allowing heat to be transferred more quickly and evenly. The viscosity of the vinyl silicone oil directly affects the fluidity of the thermally conductive insulating sheet. Vinyl silicone oil with lower viscosity makes the thermally conductive insulating sheet easier to fill and cure, thereby improving production efficiency; on the contrary, vinyl silicone oil with higher viscosity has poor fluidity during processing and is difficult to evenly cover the surface that needs heat dissipation. In addition, with the increase in the viscosity of vinyl silicone oil, the hardness and tensile strength of the thermally conductive silicone may show a trend of increasing first and then decreasing. This is mainly because the molecular chain of vinyl silicone oil with higher viscosity is longer and there are more cross-linking points on the molecular chain, thus forming a more complete cross-linking network structure during the curing process. When the viscosity is too high, the cross-linking points are too dense, which may cause the thermally conductive insulating sheet substrate to easily produce stress concentration under stress, ultimately affecting the mechanical properties of the product; in addition, the vinyl content of vinyl silicone oil will also directly affect the mechanical properties of the thermally conductive insulating sheet. The higher the vinyl content, the greater the crosslinking density of the thermally conductive insulating sheet is generally, and the higher the hardness is also; however, too high a vinyl content may also cause the thermally conductive insulating sheet to become brittle and reduce its aging resistance. Therefore, the present invention preferably uses a vinyl silicone oil with a viscosity of 10000-100000 mPa·S at 25°C and a vinyl content of 0.3-0.45%, which can ensure that the thermally conductive insulating sheet has both high thermal conductivity and high mechanical strength; the thermal conductivity of the product thermally conductive insulating sheet is greater than 3W / m·k, the tensile strength is not less than 3MPa, and the elongation at break is not less than 40%; at the same time, the insulation performance of the thermally conductive insulating sheet can also be guaranteed, and the breakdown voltage of the thermally conductive insulating sheet is not less than 7KV As an implementable case, the thermally conductive filler includes spherical thermally conductive filler and spherical-like thermally conductive filler.

[0013] Furthermore, the mass ratio of the spherical thermally conductive filler to the quasi-spherical thermally conductive filler is (40-60):(120-150); and may include one of 40:140, 60:150, and 47:123.

[0014] Furthermore, the particle size of the spherical thermally conductive filler is 0.2-10 μm, and the particle size of the quasi-spherical thermally conductive filler is 0.3-34 μm.

[0015] Furthermore, the particle size of the spherical thermally conductive filler is 0.2-3 μm, and the particle size of the quasi-spherical thermally conductive filler is 0.3-20 μm.

[0016] As an implementable case, the spherical thermal conductive filler includes: one or more of spherical alumina, spherical boron nitride, spherical aluminum nitride, spherical zinc oxide, spherical magnesium oxide, spherical silicon carbide, spherical silicon nitride, and spherical quartz powder.

[0017] Furthermore, the spherical thermal conductive filler includes one or more of spherical aluminum oxide, spherical zinc oxide, and spherical boron nitride.

[0018] As an implementable case, the spherical thermal conductive filler includes: one or more of spherical aluminum oxide, spherical boron nitride, spherical aluminum nitride, spherical zinc oxide, spherical magnesium oxide, spherical silicon carbide, spherical silicon nitride, and spherical quartz powder.

[0019] Furthermore, the spherical thermal conductive filler includes one or more of spherical aluminum oxide, spherical zinc oxide, and spherical boron nitride.

[0020] Spherical thermal conductive fillers and quasi-spherical thermal conductive fillers can combine with each other in the matrix to form a thermal conductive network similar to a mesh or chain. This network structure is conducive to the transfer of heat, thereby improving the thermal conductivity of the thermally conductive insulating sheet. Quasi-spherical thermal conductive fillers can play a key role in compounding due to their single crystal particles, high conversion rate, smooth particle surface and other characteristics, especially when the mass ratio of spherical thermal conductive fillers and quasi-spherical thermal conductive fillers is (40-60): (120-150), the thermal conductivity of the thermally conductive insulating sheet can be significantly improved, and the technical effect of high thermal conductivity and high mechanical strength can be achieved simultaneously; however, with the increase of the filling amount of thermal conductive fillers, the strength of the thermally conductive insulating sheet usually increases first and then decreases; at an appropriate filling amount, the compounding of spherical and quasi-spherical thermal conductive fillers can also enhance the mechanical properties of the thermally conductive insulating sheet, but when the mass ratio is not within the specified range, the mechanical properties of the thermally conductive insulating sheet will decrease due to the enhanced interaction between the spherical thermal conductive fillers and the quasi-spherical thermal conductive fillers.

[0021] As an practicable example, the dispersant includes at least one of modified organic silicon, titanate, stearic acid, aluminate, silane coupling agent, pentaerythritol ester, and acrylic leveling agent. Furthermore, the dispersant includes silicon: one of silane coupling agent, aluminate, stearic acid, titanate, and modified organic silicon.

[0022] Dispersants can effectively prevent the aggregation and sedimentation of thermally conductive fillers by reducing the interfacial tension between the thermally conductive fillers and the liquid medium silicone oil, thereby improving the dispersion stability of the entire system. Dispersants can further improve the thermal conductivity of thermally conductive insulating sheets by optimizing the dispersion state of thermally conductive fillers.

[0023] As an implementable example, the raw material for preparing the thermally conductive insulating sheet may further include 0.2-40 parts of a diluent.

[0024] As an implementable case, the diluent includes at least one of n-hexane, toluene, petroleum ether, isoparaffins, acetone, and butanol.

[0025] Furthermore, the diluent includes: one of petroleum ether, isoparaffins, and toluene.

[0026] A second aspect of the present invention provides a method for preparing a high-strength substrate-free thermally conductive insulating sheet, comprising: S1. Mix the thermal conductive filler in a vacuum drying oven, bake at 150-210°C for 4-8h, and then cool naturally to 25-30°C; S2. Add a dispersant to the thermally conductive filler obtained in step S1, mix well, put into a vacuum drying oven, bake at 80-120° C. for 0.5-2 h, and then cool naturally to 25-30° C. to obtain a base material; S3, adding silicone oil to the base material obtained in step S2, mixing evenly, degassing and packaging to obtain a semi-finished product; S4, the semi-finished product obtained in step S3 is subjected to a calendering process, wherein the bottom film is a release film and the upper film is a release film, and is subjected to double-roll calendering, and then passed through a drying tunnel at a temperature of 120-190° C. and a length of 6-25 m, and dried at a speed of 0.5-10 m / min, and after removing the bottom film and the upper film, it is rewound once into a roll to obtain the product.

[0027] As an practicable example, when the raw materials include a diluent, the steps for preparing a high-strength substrate-free thermally conductive insulating sheet include: S1. Mix the thermal conductive filler in a vacuum drying oven, bake at 150-210°C for 4-8h, and then cool naturally to 25-30°C; S2. Add a dispersant to the thermally conductive filler obtained in step S1, mix well, put into a vacuum drying oven, bake at 80-120° C. for 0.5-2 h, and then cool naturally to 25-30° C. to obtain a base material; S3, adding silicone oil to the base material obtained in step S2, mixing evenly, then adding diluent, mixing evenly, degassing and packaging to obtain a semi-finished product; S4, the semi-finished product obtained in step S3 is subjected to a coating process, wherein the base film is a release film, which is coated by a scraper, and then passed through a drying tunnel at a temperature of 120-190° C. and a length of 6-25 m, and dried at a speed of 0.5-10 m / min. After removing the release film, the semi-finished product is rewound once into a roll.

[0028] In the preparation system of the present invention, whether to add a diluent to the raw material system can be reasonably selected according to the actual performance of the product, and the thermally conductive insulating sheet provided by the present invention can be prepared by calendering and coating processes. The actual use performance of the product is excellent, and after use, the comprehensive performance and service life of the electronic product can be effectively improved.

[0029] Beneficial Effects (i) The thermally conductive insulating sheet provided by the present invention has excellent thermal conductivity and insulation performance, a thermal conductivity coefficient greater than 3W / m·k, and excellent insulation performance, and a breakdown voltage of not less than 7KV.

[0030] (ii) The present invention creatively develops a thermally conductive insulating sheet without a substrate, which has lower cost and simpler preparation process than thermally conductive insulating sheets with a substrate; at the same time, the thermally conductive insulating sheet has excellent mechanical properties, with a tensile strength of not less than 3MPa and an elongation at break of not less than 40%.

[0031] (III) In the present invention, by selecting a specific spherical thermally conductive filler and a quasi-spherical thermally conductive filler as a composite thermally conductive filler, the thermally conductive insulating sheet can simultaneously achieve the technical effects of high thermal conductivity and high mechanical strength.

[0032] (IV) In the present invention, vinyl silicone oil with a viscosity of 10000-100000 mPa·S and a vinyl content of 0.3-0.45% is selected as the organic silicone oil, which can ensure high insulation performance, high thermal conductivity and high mechanical strength of the thermally conductive insulating sheet.

[0033] (V) In the preparation system of the present invention, it is also possible to reasonably select whether to add a diluent to the raw material system according to the actual performance of the product, and the thermally conductive insulating sheet can be prepared by calendering and coating processes, and the actual performance of the product is excellent. DETAILED DESCRIPTION

[0034] Test Group 1 (High-strength thermally conductive insulating sheet without substrate, the raw material does not include diluent) Example 1 In a first aspect of this example, a high-strength substrate-free thermally conductive insulating sheet is provided, and the raw materials for its preparation include, by weight: 12 parts of silicone oil, 180 parts of thermally conductive filler, and 0.5 parts of dispersant.

[0035] The thermally conductive filler comprises 40 parts of spherical thermally conductive filler and 140 parts of quasi-spherical thermally conductive filler in terms of mass fraction.

[0036] The spherical thermal conductive filler comprises: spherical aluminum oxide with a particle size of 20 μm, spherical boron nitride with a particle size of 10 μm, and spherical aluminum oxide with a particle size of 20 μm, and the mass ratio of the three components is 115:5:20.

[0037] The spherical thermal conductive filler includes spherical aluminum oxide with a particle size of 3 μm.

[0038] Among them: spherical alumina with a particle size of 20 μm was purchased from Tianjin Jersey New Materials Co., Ltd., model: SHA-20.

[0039] Spherical boron nitride with a particle size of 10 μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: PBN-10.

[0040] Spherical alumina with a particle size of 20 μm was purchased from Sumitomo Corporation of Japan, model: AA-03.

[0041] Spherical alumina with a particle size of 3 μm was purchased from Tokyo Electric Chemical Industry Co., Ltd., model: DAW-3.

[0042] The organic silicone oil is vinyl silicone oil with a viscosity of 20000 mPa·S and a vinyl content of 0.45 mol %, model RH-Vi302D, purchased from Ningbo Runhe High-tech Materials Technology Co., Ltd.

[0043] The dispersant is stearic acid.

[0044] The second aspect of this example provides a method for preparing a high-strength substrate-free thermally conductive insulating sheet, comprising: S1. Place the thermal conductive filler in a vacuum drying oven and mix well, bake at 180°C for 6 hours, and then cool naturally to 25°C; S2. Add a dispersant to the thermally conductive filler obtained in step S1, mix well, put into a vacuum drying oven, bake at 90° C. for 1 hour, and then cool naturally to 25° C. to obtain a base material; S3, adding silicone oil to the base material obtained in step S2, mixing evenly, degassing for 40 minutes under a pressure of -0.1 MPa, and packaging to obtain a semi-finished product; S4, the semi-finished product obtained in step S3 is calendered, the bottom film is a fluorine PET release film, the upper film is a fluorine PET release film, after double-roll calendering, the calendering thickness is 0.29mm, and then passed through a drying tunnel with a temperature of 140°C and a length of 12m, and dried at a speed of 3m / min. After removing the bottom film and the upper film, it is rewound once into a roll.

[0045] Example 2 In a first aspect of this example, a high-strength substrate-free thermally conductive insulating sheet is provided, and the raw materials for its preparation include, by weight: 15 parts of silicone oil, 210 parts of thermally conductive filler, and 0.6 parts of dispersant.

[0046] The thermally conductive filler comprises 60 parts of spherical thermally conductive filler and 150 parts of quasi-spherical thermally conductive filler in terms of mass fraction.

[0047] The spherical thermal conductive filler comprises: spherical aluminum oxide with a particle size of 10 μm and spherical boron nitride with a particle size of 5 μm, and the mass ratio of the two components is 14:1.

[0048] The spherical thermal conductive filler comprises: spherical aluminum oxide with a particle size of 1 μm and spherical zinc oxide with a particle size of 0.2 μm, and the mass ratio of the two components is 2:1.

[0049] The spherical alumina with a particle size of 10 μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: SHA-10.

[0050] Spherical boron nitride with a particle size of 5 μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: PBN-5.

[0051] Spherical alumina with a particle size of 1 μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: Bak-1.

[0052] Spherical zinc oxide with a particle size of 0.2 μm was purchased from Horsehead Company, USA, model: kadox911.

[0053] The organic silicone oil is vinyl silicone oil with a viscosity of 100000 mPa·S and a vinyl content of 0.3 mol %, model RH-Vi301, purchased from Ningbo Runhe High-tech Materials Technology Co., Ltd.

[0054] The dispersant is dodecyltriethoxysilane.

[0055] The second aspect of this example provides a method for preparing a high-strength substrate-free thermally conductive insulating sheet, comprising: S1. Place the thermal conductive filler in a vacuum drying oven and mix well, bake at 190°C for 4 hours, and then cool naturally to 25°C; S2. Add a dispersant to the thermally conductive filler obtained in step S1, mix well, put into a vacuum drying oven, bake at 120° C. for 2 h, and then cool naturally to 25° C. to obtain a base material; S3, adding silicone oil to the base material obtained in step S2, mixing evenly, degassing for 40 minutes under a pressure of -0.1 MPa, and packaging to obtain a semi-finished product; S4, the semi-finished product obtained in step S3 is calendered, the bottom film is a fluorine PET release film, the upper film is a fluorine PET release film, after double-roll calendering, the calendering thickness is 0.19mm, and then passed through a drying tunnel with a temperature of 130°C and a length of 12m, and dried at a speed of 2m / min. After removing the bottom film and the upper film, it is rewound once into a roll.

[0056] Example 3 In a first aspect of this example, a high-strength substrate-free thermally conductive insulating sheet is provided, and the raw materials for its preparation include, by weight: 17 parts of silicone oil, 170 parts of thermally conductive filler, and 0.7 parts of dispersant.

[0057] The thermally conductive filler comprises 47 parts of spherical thermally conductive fillers and 123 parts of quasi-spherical thermally conductive fillers in terms of mass fractions.

[0058] The spherical thermal conductive filler comprises: spherical aluminum oxide with a particle size of 5 μm and spherical boron nitride with a particle size of 5 μm, and the mass ratio of the two components is 40:1.

[0059] The spherical thermal conductive filler comprises: spherical aluminum oxide with a particle size of 0.6 μm and spherical zinc oxide with a particle size of 0.2 μm, and the mass ratio of the two components is 30:17.

[0060] The spherical alumina with a particle size of 5 μm was purchased from Sumitomo Corporation of Japan, model: AA-5.

[0061] Spherical boron nitride with a particle size of 5 μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: ABN-5.

[0062] Spherical alumina with a particle size of 0.6 μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: NSM1S.

[0063] Spherical zinc oxide with a particle size of 0.2 μm was purchased from Horsehead Company, USA, model: kadox911.

[0064] The organic silicone oil is vinyl silicone oil with a viscosity of 15000 mPa·S and a vinyl content of 0.43 mol %. The model is SY-15000 and it was purchased from Ningbo Daoruo Organic Silicone Co., Ltd.

[0065] The dispersant is modified silicone, model UM-5171, purchased from Wuhan Enric Materials Co., Ltd.

[0066] The second aspect of this example provides a method for preparing a high-strength substrate-free thermally conductive insulating sheet, comprising: S1. Place the thermal conductive filler in a vacuum drying oven and mix well, bake at 150°C for 8 hours, and then cool naturally to 25°C; S2. Add a dispersant to the thermally conductive filler obtained in step S1, mix well, put into a vacuum drying oven, bake at 120° C. for 0.5 h, and then cool naturally to 25° C. to obtain a base material; S3, adding silicone oil to the base material obtained in step S2, mixing evenly, degassing for 40 minutes under a pressure of -0.1 MPa, and packaging to obtain a semi-finished product; S4, the semi-finished product obtained in step S3 is calendered, the bottom film is a fluorinated PET release film, and the upper film is a fluorinated PET release film. After double-roll calendering, the calendering thickness is 0.09 mm, and then passed through a drying tunnel with a temperature of 170° C. and a length of 14 m, and dried at a speed of 1 m / min. After removing the bottom film and the upper film, it is rewound once into a roll.

[0067] Comparative Example 1 In a first aspect of this example, a high-strength substrate-free thermally conductive insulating sheet is provided, and the raw materials for its preparation include, by weight: 14 parts of silicone oil, 175 parts of thermally conductive filler, and 0.3 parts of dispersant.

[0068] The thermal conductive filler includes, by weight, spherical alumina with a particle size of 10 μm, spherical alumina with a particle size of 2 μm and spherical alumina with a particle size of 0.5 μm, with a weight ratio of 130:30:15.

[0069] The spherical alumina with a particle size of 10 μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: Bak-10.

[0070] Spherical alumina with a particle size of 2 μm was purchased from: Chalco Shanxi New Materials Co., Ltd., model: ASF-2.

[0071] Spherical alumina with a particle size of 0.5 μm was purchased from Sumitomo Corporation of Japan, model: AA-05.

[0072] The organic silicone oil is vinyl silicone oil with a viscosity of 10000 mPa·S and a vinyl content of 0.7 mol %, model SY-10000, purchased from Ningbo Daoruo Organic Silicone Co., Ltd.

[0073] The dispersant is hexadecyltriethoxysilane.

[0074] The second aspect of this example provides a method for preparing a high-strength substrate-free thermally conductive insulating sheet, comprising: S1. Place the thermal conductive filler in a vacuum drying oven and mix well, bake at 200°C for 8 hours, and then cool naturally to 25°C; S2. Add a dispersant to the thermally conductive filler obtained in step S1, mix well, put into a vacuum drying oven, bake at 120° C. for 0.5 h, and then cool naturally to 25° C. to obtain a base material; S3, adding silicone oil to the base material obtained in step S2, mixing evenly, degassing for 30 minutes under a pressure of -0.1 MPa, and packaging to obtain a semi-finished product; S4, the semi-finished product obtained in step S3 is calendered, the bottom film is a fluorine PET release film, the upper film is a fluorine PET release film, after double-roll calendering, the calendering thickness is 0.2mm, and then passed through a drying tunnel with a temperature of 120°C and a length of 12m, and dried at a speed of 1m / min. After removing the bottom film and the upper film, it is rewound once into a roll.

[0075] Test Group 2 (High-strength thermally conductive insulating sheet without substrate, including raw materials including diluent) Example 4 In a first aspect of this example, a high-strength substrate-free thermally conductive insulating sheet is provided, and the raw materials for its preparation include, by weight: 17 parts of silicone oil, 180 parts of thermally conductive filler, 0.5 parts of dispersant, and 10 parts of diluent.

[0076] The thermally conductive filler comprises 40 parts of spherical thermally conductive filler and 140 parts of quasi-spherical thermally conductive filler in terms of mass fraction.

[0077] The spherical thermal conductive filler comprises: spherical aluminum oxide with a particle size of 15 μm, spherical boron nitride with a particle size of 10 μm and spherical aluminum oxide with a particle size of 0.3 μm; the mass ratio of the three components is 115:5:20.

[0078] The spherical thermal conductive filler includes spherical aluminum oxide with a particle size of 3 μm.

[0079] Among them, the spherical alumina with a particle size of 15 μm was purchased from Tianjin Jersey New Materials Co., Ltd., model: SHA-10.

[0080] Spherical boron nitride with a particle size of 10 μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: PBN-10.

[0081] Spherical alumina with a particle size of 0.3 μm was purchased from Sumitomo Corporation of Japan, model: AA-03.

[0082] Spherical alumina with a particle size of 3 μm was purchased from Tokyo Electric Chemical Industry Co., Ltd., model: DAW-3.

[0083] The organic silicone oil is vinyl silicone oil with a viscosity of 20000 mPa·S and a vinyl content of 0.45 mol %, model RH-Vi302D, purchased from Ningbo Runhe High-tech Materials Technology Co., Ltd.

[0084] The dispersant is stearic acid.

[0085] The diluent is petroleum ether The second aspect of this example provides a method for preparing a high-strength substrate-free thermally conductive insulating sheet, comprising: S1. Place the thermal conductive filler in a vacuum drying oven and mix well, bake at 180°C for 6 hours, and then cool naturally to 25°C; S2. Add a dispersant to the thermally conductive filler obtained in step S1, mix well, put into a vacuum drying oven, bake at 90° C. for 1 hour, and then cool naturally to 25° C. to obtain a base material; S3, adding silicone oil to the base material obtained in step S2, mixing evenly, adding diluent, mixing evenly, degassing for 40 minutes under a pressure of -0.1 MPa, and packaging to obtain the semi-finished product; S4, placing the semi-finished product obtained in step S3 on a fluorine PET release film, coating with a coating scraper to set the thickness, the coating thickness is 0.2mm, and then passing through a drying tunnel at a temperature of 140°C and a length of 12m, drying at a speed of 3m / min, removing the fluorine PET release film, and rewinding it into a roll.

[0086] Example 5 In a first aspect of this example, a high-strength substrate-free thermally conductive insulating sheet is provided, and the raw materials for its preparation include, by weight: 19 parts of silicone oil, 210 parts of thermally conductive filler, 0.6 parts of dispersant, and 15 parts of diluent.

[0087] The thermally conductive filler comprises 60 parts of spherical thermally conductive filler and 150 parts of quasi-spherical thermally conductive filler in terms of mass fraction.

[0088] The spherical thermal conductive filler comprises: spherical aluminum oxide with a particle size of 10 μm and spherical boron nitride with a particle size of 5 μm, and the mass ratio of the two components is 14:1.

[0089] The spherical thermal conductive filler comprises: spherical aluminum oxide with a particle size of 1 μm and spherical zinc oxide with a particle size of 0.2 μm, and the mass ratio of the two components is 2:1.

[0090] The spherical alumina with a particle size of 10 μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: SHA-10.

[0091] Spherical boron nitride with a particle size of 5 μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: PBN-5.

[0092] Spherical alumina with a particle size of 1 μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: Bak-1.

[0093] Spherical zinc oxide with a particle size of 0.2 μm was purchased from Horsehead Company, USA, model: kadox911.

[0094] The organic silicone oil is vinyl silicone oil with a viscosity of 100000 mPa·S and a vinyl content of 0.3 mol %, model RH-Vi301, purchased from Ningbo Runhe High-tech Materials Technology Co., Ltd.

[0095] The dispersant is dodecyltriethoxysilane.

[0096] The diluent is petroleum ether.

[0097] The second aspect of this example provides a method for preparing a high-strength substrate-free thermally conductive insulating sheet, comprising: S1. Place the thermal conductive filler in a vacuum drying oven and mix well, bake at 190°C for 4 hours, and then cool naturally to 25°C; S2. Add a dispersant to the thermally conductive filler obtained in step S1, mix well, put into a vacuum drying oven, bake at 120° C. for 2 h, and then cool naturally to 25° C. to obtain a base material; S3, adding silicone oil to the base material obtained in step S2, mixing evenly, adding diluent, mixing evenly, degassing for 40 minutes under a pressure of -0.1 MPa, and packaging to obtain the semi-finished product; S4, placing the semi-finished product obtained in step S3 on a fluorine PET release film, coating with a coating scraper to set the thickness, the coating thickness is 0.2mm, and then passing through a drying tunnel at a temperature of 130°C and a length of 12m, drying at a speed of 2m / min, removing the fluorine PET release film, and rewinding it into a roll.

[0098] Example 6 In the first aspect of this example, a high-strength substrate-free thermally conductive insulating sheet is provided, and the raw materials for its preparation include, by weight: 20 parts of silicone oil, 170 parts of thermally conductive filler, 0.7 parts of dispersant, and 20 parts of diluent.

[0099] The thermally conductive filler comprises 47 parts of spherical thermally conductive fillers and 123 parts of quasi-spherical thermally conductive fillers in terms of mass fractions.

[0100] The spherical thermal conductive filler comprises: spherical aluminum oxide with a particle size of 3 μm and spherical boron nitride with a particle size of 5 μm, and the mass ratio of the two components is 40:1.

[0101] The spherical thermal conductive filler comprises: spherical aluminum oxide with a particle size of 0.6 μm and spherical zinc oxide with a particle size of 0.2 μm, and the mass ratio of the two components is 30:17.

[0102] The spherical alumina with a particle size of 3 μm was purchased from Sumitomo Corporation of Japan, model: AA-3.

[0103] Spherical boron nitride with a particle size of 5 μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: ABN-5.

[0104] Spherical alumina with a particle size of 0.6 μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: NSM1S.

[0105] Spherical zinc oxide with a particle size of 0.2 μm was purchased from Horsehead Company, USA, model: kadox911.

[0106] The organic silicone oil is vinyl silicone oil with a viscosity of 15000 mPa·S and a vinyl content of 0.43 mol %. The model is SY-15000 and it was purchased from Ningbo Daoruo Organic Silicone Co., Ltd.

[0107] The dispersant is modified silicone, model UM-5171, purchased from Wuhan Enric Materials Co., Ltd.

[0108] The diluent is toluene.

[0109] The second aspect of this example provides a method for preparing a high-strength substrate-free thermally conductive insulating sheet, comprising: S1. Place the thermal conductive filler in a vacuum drying oven and mix well, bake at 150°C for 8 hours, and then cool naturally to 25°C; S2. Add a dispersant to the thermally conductive filler obtained in step S1, mix well, put into a vacuum drying oven, bake at 120° C. for 0.5 h, and then cool naturally to 25° C. to obtain a base material; S3, adding silicone oil to the base material obtained in step S2, mixing evenly, adding diluent, mixing evenly, degassing for 40 minutes under a pressure of -0.1 MPa, and packaging to obtain the semi-finished product; S4, placing the semi-finished product obtained in step S3 on a fluorine PET release film, coating with a coating scraper to set the thickness, the coating thickness is 0.2mm, and then passing through a drying tunnel at a temperature of 170°C and a length of 14m, drying at a speed of 1m / min, removing the fluorine PET release film, and rewinding it into a roll.

[0110] Comparative Example 2 In the first aspect of this example, a high-strength substrate-free thermally conductive insulating sheet is provided, and the raw materials for its preparation include, by weight: 12 parts of silicone oil, 175 parts of thermally conductive filler, 0.3 parts of dispersant, and 5 parts of diluent.

[0111] The thermal conductive filler comprises: spherical alumina with a particle size of 10 μm, spherical alumina with a particle size of 2 μm and spherical alumina with a particle size of 0.5 μm, with a weight ratio of 130:30:15.

[0112] The spherical alumina with a particle size of 10 μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: Bak-10.

[0113] Spherical alumina with a particle size of 2 μm was purchased from: Chalco Shanxi New Materials Co., Ltd., model: ASF-2.

[0114] Spherical alumina with a particle size of 0.5 μm was purchased from Sumitomo Corporation of Japan, model: AA-05.

[0115] The organic silicone oil is vinyl silicone oil with a viscosity of 10000 mPa·S and a vinyl content of 0.7 mol %, model SY-10000, purchased from Ningbo Daoruo Organic Silicone Co., Ltd.

[0116] The dispersant is hexadecyltriethoxysilane.

[0117] The diluent is toluene.

[0118] The second aspect of this example provides a method for preparing a high-strength substrate-free thermally conductive insulating sheet, comprising: S1. Place the thermal conductive filler in a vacuum drying oven and mix well, bake at 200°C for 6 hours, and then cool naturally to 25°C; S2. Add a dispersant to the thermally conductive filler obtained in step S1, mix well, put into a vacuum drying oven, bake at 120° C. for 0.5 h, and then cool naturally to 25° C. to obtain a base material; S3, adding silicone oil to the base material obtained in step S2, mixing evenly, adding diluent, mixing evenly, degassing for 30 minutes under a pressure of -0.1 MPa, and packaging to obtain the semi-finished product; S4, placing the semi-finished product obtained in step S3 on a fluorine PET release film, coating with a coating scraper to set the thickness, the coating thickness is 0.2mm, and then passing through a drying tunnel with a temperature of 120°C and a length of 12m, drying at a speed of 1m / min, removing the fluorine PET release film, and rewinding it into a roll.

[0119] Performance Evaluation 1. Thickness: Referring to ASTM D374, the thickness of the thermally conductive insulating sheets prepared in Examples 1-6 and Comparative Examples 1-2 was tested.

[0120] 2. Contact thermal resistance: Referring to ASTM 5470, the contact thermal resistance of the thermally conductive insulating sheets prepared in Examples 1-6 and Comparative Examples 1-2 was tested.

[0121] 3. Thermal conductivity: Referring to ISO 22007-2, the thermal conductivity of the thermally conductive insulating sheets prepared in Examples 1-6 and Comparative Examples 1-2 was tested.

[0122] 4. Breakdown voltage: Referring to ASTM D149, the breakdown voltages of the thermally conductive insulating sheets prepared in Examples 1-6 and Comparative Examples 1-2 were tested.

[0123] The test results of test group 1 are detailed in Table 1, and the test results of test group 2 are detailed in Table 2.

[0124] Table 1

[0125] Table 2

Claims

1. A high-strength substrate-free thermally conductive insulating sheet, characterized in that: The raw materials for preparation include, by weight, 10-30 parts of organic silicone oil, 110-400 parts of thermal conductive filler, and 0.2-0.7 parts of dispersant; the thermal conductivity of the thermal conductive insulating sheet is greater than 3W / m·k, and the tensile strength is greater than 3MPa.

2. The high-strength substrate-free thermally conductive insulating sheet according to claim 1, characterized in that: The organic silicone oil includes vinyl silicone oil.

3. The high-strength substrate-free thermally conductive insulating sheet according to claim 2, characterized in that: The viscosity of the vinyl silicone oil at 25° C. is 30-1,000,000 mPa·S.

4. The high-strength substrate-free thermally conductive insulating sheet according to claim 2, characterized in that: The vinyl content in the vinyl silicone oil is 0.01-6%.

5. The high-strength substrate-free thermally conductive insulating sheet according to claim 1, characterized in that: The thermally conductive filler includes a spherical thermally conductive filler and a quasi-spherical thermally conductive filler.

6. The high-strength substrate-free thermally conductive insulating sheet according to claim 5, characterized in that: The mass ratio of the spherical thermally conductive filler to the quasi-spherical thermally conductive filler is (40-60): (120-150).

7. The high-strength substrate-free thermally conductive insulating sheet according to claim 5, characterized in that: The particle size of the spherical thermal conductive filler is 0.2-10 μm, and the particle size of the quasi-spherical thermal conductive filler is 0.3-34 μm.

8. The high-strength substrate-free thermally conductive insulating sheet according to claim 5, characterized in that: The spherical heat-conductive filler includes one or more of spherical alumina, spherical boron nitride, spherical aluminum nitride, spherical zinc oxide, spherical magnesium oxide, spherical silicon carbide, spherical silicon nitride, and spherical quartz powder; The spherical thermal conductive filler includes one or more of spherical aluminum oxide, spherical boron nitride, spherical aluminum nitride, spherical zinc oxide, spherical magnesium oxide, spherical silicon carbide, spherical silicon nitride, and spherical quartz powder.

9. The high-strength substrate-free thermally conductive insulating sheet according to claim 1, characterized in that: The dispersant comprises: at least one of modified organic silicon, titanate, stearic acid, aluminate, silane coupling agent, pentaerythritol ester and acrylic ester leveling agent.

10. A method for preparing a high-strength substrate-free thermally conductive insulating sheet, the method being implemented based on the high-strength substrate-free thermally conductive insulating sheet according to any one of claims 1 to 9, characterized in that: include: S1. Place the thermal conductive filler in a vacuum drying oven and mix well, bake at 150-210°C for 4-8h, and then cool naturally to 25-30°C; S2. Add a dispersant to the thermally conductive filler obtained in step S1, mix well, put into a vacuum drying oven, bake at 80-120° C. for 0.5-2 h, and then cool naturally to 25-30° C. to obtain a base material; S3, adding silicone oil to the base material and mixing evenly to obtain a semi-finished product; S4, the semi-finished product is subjected to a calendering process, wherein the bottom film is a release film, and the upper film is a release film, and is subjected to double-roller calendering, and then dried in a drying tunnel, and after the bottom film and the upper film are removed, the semi-finished product is rewound to obtain the high-strength substrate-free thermally conductive insulating sheet.

Images