High-strength substrate-free thermally conductive insulating sheet and preparation method therefor

Abstract

The present invention relates to the field of thermally conductive materials, and more specifically to a high-strength substrate-free thermally conductive insulating sheet and a preparation method therefor. Raw materials for preparing the high-strength substrate-free thermally conductive insulating sheet provided by the present invention comprise, in parts by mass, 10-30 parts of silicone oil, 110-400 parts of a thermally conductive filler, and 0.2-0.7 parts of a dispersant, wherein the thermally conductive filler includes a spherical thermally conductive filler and a quasi‑spherical thermally conductive filler, and the mass ratio of the spherical thermally conductive filler to the quasi‑spherical thermally conductive filler is (40-60):(120-150); and the silicone oil includes vinyl silicone oil, and the vinyl silicone oil has a viscosity of 30-1,000,000 mPa·S at 25ºC and a vinyl content of 0.01-6%. The preparation of the product does not require a substrate, and the thermally conductive insulating sheet has a thermal conductivity greater than 3 W / m·k, a breakdown voltage of not less than 7 kV, and a tensile strength greater than 3 MPa, offering excellent heat dissipation and insulation effects.

Description

A high-strength substrate-free thermally conductive insulating sheet and its preparation method Technical Field

[0001] This invention belongs to the field of thermally conductive materials, and more specifically relates to a high-strength substrate-free thermally conductive insulating sheet and its preparation method. Background Technology

[0002] With the advancement of technology and the development of productivity, consumers have increasingly higher demands for the sophistication and convenience of digital products. Currently, most mainstream digital products on the market are still powered by electricity. However, electric power inevitably leads to significant heat loss during normal operation. Since the internal components of digital products are highly sensitive to heat, if the heat cannot be dissipated in time, the product's performance may be weakened due to excessive internal temperature, or even spontaneous combustion may occur, posing a significant safety hazard. Therefore, timely heat dissipation is crucial for the normal operation of digital products and reducing user safety risks. A common solution is to use a suitable thermally conductive material between the heat source and the heat sink layer of the digital product, acting as a conductive medium to dissipate the heat generated by electricity.

[0003] Thermally conductive materials used in high-precision electronic devices not only need excellent thermal conductivity but also good electrical properties. The higher the voltage across the insulator inside an electronic device, the greater the electric field force on the insulator, leading to ionization collisions and potentially causing insulator breakdown, posing a significant safety hazard. Therefore, there is an urgent need for a thermally conductive material capable of withstanding high breakdown voltages.

[0004] Thermally conductive insulating sheets are primarily used at the interface between electronic devices and heat sinks or product housings. Due to their high reliability, insulation, low contact thermal resistance, and high thermal conductivity, they are widely used in communication equipment, computers, and home appliances. The most significant characteristic of thermally conductive insulating sheets is their thinness, typically between 0.05-0.5 mm, enabling their application in high-precision equipment. However, excessively thin materials, under prolonged overheating conditions or as the material ages and deteriorates, will significantly affect the mechanical strength and normal operating performance of the thermally conductive insulating sheet. Currently, conventional thermally conductive insulating sheets on the market require a substrate to ensure mechanical strength, usually using fiberglass cloth and polyimide film as the substrate. For example, the thermally conductive silicone cloth disclosed in CN206170755U uses fiberglass cloth as the substrate. However, products using certain substrates are more expensive, increasing production costs and making the manufacturing process more complex. For example, thermal conductive products based on fiberglass cloth can only be made into products with low thermal conductivity, which cannot effectively solve the heat dissipation problem. At the same time, the production process of fiberglass cloth is also relatively complex. Although the production process of polyimide substrate 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 combines 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] To solve the above-mentioned technical problems, the first aspect of the present invention provides a high-strength, substrate-free thermally conductive insulating sheet, the raw materials for which are prepared by mass include: 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 3 W / m·K, and the tensile strength is greater than 3 MPa.

[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 example of an implementable practice, the silicone oil mentioned includes vinyl silicone oil.

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

[0010] Furthermore, the viscosity of the vinyl silicone oil at 25°C is 10,000-100,000 mPa·s.

[0011] Furthermore, the vinyl content in the vinyl silicone oil is 0.01-6%.

[0012] Furthermore, the vinyl content in the vinyl silicone oil is 0.3-0.45%.

[0013] Vinyl silicone oil possesses a certain degree of thermal conductivity due to its molecular structure. Adding an appropriate amount of vinyl silicone oil to thermally conductive insulating sheets can effectively improve the material's thermal conductivity, allowing for faster and more uniform heat transfer. The viscosity of the vinyl silicone oil directly affects the flowability of the thermally conductive insulating sheet. Lower viscosity vinyl silicone oil makes the sheet easier to fill and cure, thus improving production efficiency; conversely, higher viscosity vinyl silicone oil has poor flowability during processing, making it difficult to evenly cover the surface requiring heat dissipation. Furthermore, as the viscosity of the vinyl silicone oil increases, the hardness and tensile strength of the thermally conductive silicone may initially increase and then decrease. This is mainly because higher viscosity vinyl silicone oil has longer molecular chains and more cross-linking points, resulting in a more complete cross-linked network structure during curing. When the viscosity is too high, the excessively dense cross-linking points may cause stress concentration in the thermally conductive insulating sheet matrix under stress, ultimately affecting the product's mechanical properties. Additionally, the vinyl content of the vinyl silicone oil also directly affects the mechanical properties of the thermally conductive insulating sheet. Higher vinyl content generally results in greater crosslinking density and higher hardness of the thermally conductive insulating sheet; however, excessively high vinyl content can also lead to brittleness and decreased aging resistance. Therefore, this invention preferably uses vinyl silicone oil with a viscosity of 10,000-100,000 mPa·s at 25°C and a vinyl content of 0.3-0.45%, which ensures that the thermally conductive insulating sheet possesses both high thermal conductivity and high mechanical strength. The thermal conductivity of the product's thermally conductive insulating sheet is greater than 3 W / m·K, the tensile strength is not less than 3 MPa, and the elongation at break is not less than 40%. Simultaneously, the insulation performance of the thermally conductive insulating sheet is also guaranteed, with a breakdown voltage of not less than 7 kV.

[0014] As an example of implementation, the thermally conductive filler includes spherical thermally conductive fillers and quasi-spherical thermally conductive fillers.

[0015] Furthermore, the mass ratio of the spherical thermally conductive filler to the near-spherical thermally conductive filler is (40-60):(120-150); it may include one of 40:140, 60:150, or 47:123.

[0016] Furthermore, the particle size of the spherical thermally conductive filler is 0.2-10 μm, and the particle size of the near-spherical thermally conductive filler is 0.3-34 μm.

[0017] Furthermore, the particle size of the spherical thermally conductive filler is 0.2-3 μm, and the particle size of the near-spherical thermally conductive filler is 0.3-20 μm.

[0018] As an implementable example, the spherical thermally conductive filler includes one or more of the following: spherical alumina, 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 thermally conductive filler includes one or more of the following: spherical alumina, spherical zinc oxide, and spherical boron nitride.

[0020] As an implementable example, the spherical thermally conductive filler includes one or more of the following: spherical alumina, spherical boron nitride, spherical aluminum nitride, spherical zinc oxide, spherical magnesium oxide, spherical silicon carbide, spherical silicon nitride, and spherical quartz powder.

[0021] Furthermore, the spherical thermally conductive filler includes one or more of the following: spherical alumina, spherical zinc oxide, and spherical boron nitride.

[0022] Spherical and near-spherical thermally conductive fillers can combine with each other in the matrix to form a mesh-like or chain-like thermally conductive network. This network structure facilitates heat transfer, thereby improving the thermal conductivity of the thermally conductive insulation sheet. Near-spherical thermally conductive fillers, due to their single-crystal particles, high conversion rate, and smooth particle surface, play a crucial role in the compounding process. Especially when the mass ratio of spherical to near-spherical thermally conductive fillers is (40-60):(120-150), the thermal conductivity of the thermally conductive insulation sheet can be significantly improved, simultaneously achieving high thermal conductivity and high mechanical strength. However, as the filler content increases, the strength of the thermally conductive insulation sheet usually increases first and then decreases. With appropriate filler content, the compounding of spherical and near-spherical thermally conductive fillers can further enhance the mechanical properties of the thermally conductive insulation sheet. However, when the mass ratio is outside the specified range, the enhanced interaction between the spherical and near-spherical thermally conductive fillers can lead to a decrease in the mechanical properties of the thermally conductive insulation sheet.

[0023] As an implementable example, the dispersant comprises at least one of the following: modified organosilicon, titanate, stearic acid, aluminate, silane coupling agent, pentaerythritol ester, and acrylate leveling agent.

[0024] Furthermore, the dispersant includes one of the following: silicon: silane coupling agent, aluminate, stearic acid, titanate, and modified organosilicon.

[0025] Dispersants can effectively prevent the aggregation and sedimentation of thermally conductive fillers by reducing the interfacial tension between the thermally conductive filler 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.

[0026] As an example of implementation, the raw materials for preparing the thermally conductive insulating sheet may also include 0.2-40 parts of diluent.

[0027] As an implementable example, the diluent includes at least one of the following: n-hexane, toluene, petroleum ether, isoparaffins, acetone, and butanol.

[0028] Furthermore, the diluent includes one of petroleum ether, isoparaffins, and toluene.

[0029] A second aspect of the present invention provides a method for preparing a high-strength, substrate-free thermally conductive insulating sheet, comprising:

[0030] S1. Place the thermally conductive filler in a vacuum drying oven and mix evenly. Bake at 150-210℃ for 4-8 hours, then cool naturally to 25-30℃.

[0031] S2. Add dispersant to the thermally conductive filler obtained in step S1, mix evenly, place in a vacuum drying oven, bake at 80-120℃ for 0.5-2 hours, and then cool naturally to 25-30℃ to obtain the base material;

[0032] S3. Add silicone oil to the base material obtained in step S2, mix evenly, and then degas and package to obtain the semi-finished product.

[0033] S4. The semi-finished product obtained in step S3 is subjected to a calendering process. The bottom film is a release film and the top film is a release film. After being calendered by two rollers, it is dried in a drying tunnel with a temperature of 120-190℃ and a length of 6-25m at a speed of 0.5-10m / min. After removing the bottom film and the top film, it is rewound once to obtain the final product.

[0034] As an feasible example, when the raw materials include a diluent, the preparation steps for a high-strength substrate-free thermally conductive insulating sheet include:

[0035] S1. Place the thermally conductive filler in a vacuum drying oven and mix evenly. Bake at 150-210℃ for 4-8 hours, then cool naturally to 25-30℃.

[0036] S2. Add dispersant to the thermally conductive filler obtained in step S1, mix evenly, place in a vacuum drying oven, bake at 80-120℃ for 0.5-2 hours, and then cool naturally to 25-30℃ to obtain the base material;

[0037] S3. Add silicone oil to the base material obtained in step S2, mix evenly, then add diluent, mix evenly, degas and package to obtain semi-finished product.

[0038] S4. Apply a coating process to the semi-finished product obtained in step S3. The base film is a release film. After passing through a doctor blade, the product is dried in a drying tunnel with a temperature of 120-190℃ and a length of 6-25m at a speed of 0.5-10m / min. After removing the release film, the product is rewound once to obtain the final product.

[0039] In the preparation system of this invention, diluents can be added to the raw material system in a reasonable manner according to the actual performance of the product. Furthermore, the thermally conductive insulating sheet provided by this invention can be produced by calendering and coating processes. The actual performance of the product is excellent, and its use can effectively improve the overall performance and service life of electronic products. Beneficial effects

[0040] (i) The thermally conductive insulating sheet provided by the present invention has excellent thermal conductivity and insulation properties, with a thermal conductivity greater than 3W / m·k and excellent insulation properties, with a breakdown voltage of not less than 7KV.

[0041] (II) This invention creatively develops a substrate-free thermally conductive insulating sheet, which has a lower cost and simpler manufacturing process compared to a substrate-based thermally conductive insulating sheet; 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%.

[0042] (III) In this invention, specific spherical thermally conductive fillers and near-spherical thermally conductive fillers are selected as thermally conductive fillers, which can enable the thermally conductive insulating sheet to simultaneously achieve the technical effects of high thermal conductivity and high mechanical strength.

[0043] (iv) In this invention, a vinyl silicone oil with a viscosity of 10,000-100,000 mPa·S and a vinyl content of 0.3-0.45% was selected as the organosilicon oil, which can ensure the high insulation performance, high thermal conductivity and high mechanical strength of the thermally conductive insulating sheet.

[0044] (v) In the preparation system of this invention, diluents can be added to the raw material system according to the actual performance of the product. The thermally conductive insulating sheet can be made by calendering and coating processes, and the actual performance of the product is excellent. Detailed Implementation

[0045] Experimental Group 1 (High-strength, substrate-free thermally conductive insulating sheet, excluding diluent)

[0046] Example 1

[0047] The first aspect of this example provides a high-strength, substrate-free thermally conductive insulating sheet, the raw materials for which, by mass, include: 12 parts silicone oil, 180 parts thermally conductive filler, and 0.5 parts dispersant.

[0048] The thermally conductive filler, by weight, comprises 40 parts spherical thermally conductive filler and 140 parts near-spherical thermally conductive filler.

[0049] The spherical thermally conductive filler comprises: spherical alumina with a particle size of 20 μm, spherical boron nitride with a particle size of 10 μm, and spherical alumina with a particle size of 20 μm, with a mass ratio of 115:5:20 for the three components.

[0050] The spherical thermally conductive filler comprises spherical alumina with a particle size of 3 μm.

[0051] Among them, the spherical alumina with a particle size of 20μm was purchased from Tianjin Zexi New Materials Co., Ltd., model: SHA-20.

[0052] Spherical boron nitride with a particle size of 10μm was purchased from Sichuan Ya'an Baitu High-Tech Materials Co., Ltd., model: PBN-10.

[0053] Spherical alumina with a particle size of 20 μm was purchased from Sumitomo Corporation, Japan, model number AA-03.

[0054] Spherical alumina with a particle size of 3μm was purchased from Tokyo Electric Chemical Industry Co., Ltd., model: DAW-3.

[0055] The silicone oil is a 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.

[0056] The dispersant is stearic acid.

[0057] The second aspect of this example provides a method for preparing a high-strength, substrate-free thermally conductive insulating sheet, including:

[0058] S1. Place the thermally conductive filler in a vacuum drying oven and mix evenly. Bake at 180°C for 6 hours, then let it cool naturally to 25°C.

[0059] S2. Add dispersant to the thermally conductive filler obtained in step S1, mix evenly, place in a vacuum drying oven, bake at 90°C for 1 hour, and then cool naturally to 25°C to obtain the base material;

[0060] S3. Add organosilicon oil to the base material obtained in step S2, mix evenly, degas under a pressure of -0.1MPa for 40 minutes, and package to obtain the semi-finished product;

[0061] S4. The semi-finished product obtained in step S3 is calendered. The bottom film is a fluoroPET release film and the top film is a fluoroPET release film. After being calendered by two rollers, the calendering thickness is 0.29mm. Then, it is dried in a drying tunnel with a temperature of 140℃ and a length of 12m at a speed of 3m / min. After removing the bottom film and the top film, it is rewound once to obtain the final product.

[0062] Example 2

[0063] The first aspect of this example provides a high-strength, substrate-free thermally conductive insulating sheet, the raw materials for which, by mass, include: 15 parts silicone oil, 210 parts thermally conductive filler, and 0.6 parts dispersant.

[0064] The thermally conductive filler, by weight, comprises 60 parts of spherical thermally conductive filler and 150 parts of near-spherical thermally conductive filler.

[0065] The spherical thermally conductive filler comprises: spherical alumina with a particle size of 10 μm and spherical boron nitride with a particle size of 5 μm, with a mass ratio of 14:1 between the two components.

[0066] The spherical thermally conductive filler comprises spherical alumina with a particle size of 1 μm and spherical zinc oxide with a particle size of 0.2 μm, with a mass ratio of 2:1 between the two components.

[0067] Among them, the spherical alumina with a particle size of 10μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: SHA-10.

[0068] Spherical boron nitride with a particle size of 5μm was purchased from Sichuan Ya'an Baitu High-Tech Materials Co., Ltd., model: PBN-5.

[0069] Spherical alumina with a particle size of 1μm was purchased from Sichuan Ya'an Baitu High-Tech Materials Co., Ltd., model: Bak-1.

[0070] Spherical zinc oxide with a particle size of 0.2 μm was purchased from Horsehead, USA, model: Kadox 911.

[0071] The silicone oil is a vinyl silicone oil with a viscosity of 100,000 mPa·s and a vinyl content of 0.3 mol%, model RH-Vi301, purchased from Ningbo Runhe High-tech Materials Technology Co., Ltd.

[0072] The dispersant is dodecyltriethoxysilane.

[0073] The second aspect of this example provides a method for preparing a high-strength, substrate-free thermally conductive insulating sheet, including:

[0074] S1. Place the thermally conductive filler in a vacuum drying oven and mix evenly. Bake at 190°C for 4 hours, then let it cool naturally to 25°C.

[0075] S2. Add dispersant to the thermally conductive filler obtained in step S1, mix evenly, place in a vacuum drying oven, bake at 120℃ for 2 hours, and then cool naturally to 25℃ to obtain the base material;

[0076] S3. Add organosilicon oil to the base material obtained in step S2, mix evenly, degas under a pressure of -0.1MPa for 40 minutes, and package to obtain the semi-finished product;

[0077] S4. Calender the semi-finished product obtained in step S3. The bottom film is a fluoroPET release film and the top film is a fluoroPET release film. After calendering with two rollers, the calendering thickness is 0.19mm. Then, it is dried in a drying tunnel with a temperature of 130℃ and a length of 12m at a speed of 2m / min. After removing the bottom film and the top film, it is rewound once to obtain the final product.

[0078] Example 3

[0079] The first aspect of this example provides a high-strength, substrate-free thermally conductive insulating sheet, the raw materials for which, by mass, include: 17 parts silicone oil, 170 parts thermally conductive filler, and 0.7 parts dispersant.

[0080] The thermally conductive filler, by mass fraction, comprises 47 parts spherical thermally conductive filler and 123 parts near-spherical thermally conductive filler.

[0081] The spherical thermally conductive filler comprises: spherical alumina with a particle size of 5 μm and spherical boron nitride with a particle size of 5 μm, with a mass ratio of 40:1 between the two components.

[0082] The spherical thermally conductive filler comprises spherical alumina with a particle size of 0.6 μm and spherical zinc oxide with a particle size of 0.2 μm, with a mass ratio of 30:17 between the two components.

[0083] Among them, the spherical alumina with a particle size of 5μm was purchased from Sumitomo Corporation of Japan, model: AA-5.

[0084] Spherical boron nitride with a particle size of 5μm was purchased from Sichuan Ya'an Baitu High-Tech Materials Co., Ltd., model: ABN-5.

[0085] Spherical alumina with a particle size of 0.6 μm was purchased from Sichuan Ya'an Baitu High-Tech Materials Co., Ltd., model: NSM1S.

[0086] Spherical zinc oxide with a particle size of 0.2 μm was purchased from Horsehead, USA, model: Kadox 911.

[0087] The silicone oil is a vinyl silicone oil with a viscosity of 15000 mPa·S, a vinyl content of 0.43 mol%, and a model number of SY-15000. It was purchased from Ningbo Daoruo Silicone Co., Ltd.

[0088] The dispersant is a modified organosilicon, model UM-5171, purchased from Wuhan Anruike Materials Co., Ltd.

[0089] The second aspect of this example provides a method for preparing a high-strength, substrate-free thermally conductive insulating sheet, including:

[0090] S1. Place the thermally conductive filler in a vacuum drying oven and mix evenly. Bake at 150°C for 8 hours, then let it cool naturally to 25°C.

[0091] S2. Add dispersant to the thermally conductive filler obtained in step S1, mix evenly, place in a vacuum drying oven, bake at 120℃ for 0.5h, and then cool naturally to 25℃ to obtain the base material;

[0092] S3. Add organosilicon oil to the base material obtained in step S2, mix evenly, degas under a pressure of -0.1MPa for 40 minutes, and package to obtain the semi-finished product;

[0093] S4. Calender the semi-finished product obtained in step S3. The bottom film is a fluoroPET release film and the top film is a fluoroPET release film. After calendering with two rollers, the calendering thickness is 0.09mm. Then, it is dried in a drying tunnel with a temperature of 170℃ and a length of 14m at a speed of 1m / min. After removing the bottom film and the top film, it is rewound once to obtain the final product.

[0094] Comparative Example 1

[0095] The first aspect of this example provides a high-strength, substrate-free thermally conductive insulating sheet, the raw materials for which, by mass, include: 14 parts silicone oil, 175 parts thermally conductive filler, and 0.3 parts dispersant.

[0096] The thermally conductive filler comprises, by weight parts: 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, in a weight ratio of 130:30:15.

[0097] Among them, the spherical alumina with a particle size of 10μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: Bak-10.

[0098] Spherical alumina with a particle size of 2μm was purchased from: Chalco Shanxi New Materials Co., Ltd., model: ASF-2.

[0099] Spherical alumina with a particle size of 0.5 μm was purchased from Sumitomo Corporation, Japan, model number AA-05.

[0100] The silicone oil is a vinyl silicone oil with a viscosity of 10000 mPa·S, a vinyl content of 0.7 mol%, and a model number of SY-10000. It was purchased from Ningbo Daoruo Silicone Co., Ltd.

[0101] The dispersant is hexadecyltriethoxysilane.

[0102] The second aspect of this example provides a method for preparing a high-strength, substrate-free thermally conductive insulating sheet, including:

[0103] S1. Place the thermally conductive filler in a vacuum drying oven and mix evenly. Bake at 200℃ for 8 hours, then let it cool naturally to 25℃.

[0104] S2. Add dispersant to the thermally conductive filler obtained in step S1, mix evenly, place in a vacuum drying oven, bake at 120℃ for 0.5h, and then cool naturally to 25℃ to obtain the base material;

[0105] S3. Add silicone oil to the base material obtained in step S2, mix evenly, degas under a pressure of -0.1MPa for 30 minutes, and package to obtain the semi-finished product;

[0106] S4. Calender the semi-finished product obtained in step S3. The bottom film is a fluoroPET release film and the top film is a fluoroPET release film. After calendering with two rollers, the calendering thickness is 0.2mm. Then, it is dried in a drying tunnel with a temperature of 120℃ and a length of 12m at a speed of 1m / min. After removing the bottom film and the top film, it is rewound once to obtain the final product.

[0107] Experimental Group 2 (High-strength, substrate-free thermally conductive insulating sheet containing diluent)

[0108] Example 4

[0109] The first aspect of this example provides a high-strength, substrate-free thermally conductive insulating sheet, the raw materials for which, by mass parts, include: 17 parts silicone oil, 180 parts thermally conductive filler, 0.5 parts dispersant, and 10 parts diluent.

[0110] The thermally conductive filler, by weight, comprises 40 parts spherical thermally conductive filler and 140 parts near-spherical thermally conductive filler.

[0111] The spherical thermally conductive filler comprises: spherical alumina with a particle size of 15 μm, spherical boron nitride with a particle size of 10 μm, and spherical alumina with a particle size of 0.3 μm; the mass ratio of the three components is 115:5:20.

[0112] The spherical thermally conductive filler comprises spherical alumina with a particle size of 3 μm.

[0113] Among them, the spherical alumina with a particle size of 15μm was purchased from Tianjin Zexi New Materials Co., Ltd., model: SHA-10.

[0114] Spherical boron nitride with a particle size of 10μm was purchased from Sichuan Ya'an Baitu High-Tech Materials Co., Ltd., model: PBN-10.

[0115] Spherical alumina with a particle size of 0.3 μm was purchased from Sumitomo Corporation, Japan, model number AA-03.

[0116] Spherical alumina with a particle size of 3μm was purchased from Tokyo Electric Chemical Industry Co., Ltd., model: DAW-3.

[0117] The silicone oil is a 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.

[0118] The dispersant is stearic acid.

[0119] The diluent is petroleum ether.

[0120] The second aspect of this example provides a method for preparing a high-strength, substrate-free thermally conductive insulating sheet, including:

[0121] S1. Place the thermally conductive filler in a vacuum drying oven and mix evenly. Bake at 180°C for 6 hours, then let it cool naturally to 25°C.

[0122] S2. Add dispersant to the thermally conductive filler obtained in step S1, mix evenly, place in a vacuum drying oven, bake at 90°C for 1 hour, and then cool naturally to 25°C to obtain the base material;

[0123] S3. Add silicone oil to the base material obtained in step S2, mix evenly, add diluent, mix evenly, degas under a pressure of -0.1MPa for 40 minutes, and package to obtain the semi-finished product.

[0124] S4. Place the semi-finished product obtained in step S3 onto a fluoroPET release film, coat it with a coating blade to a thickness of 0.2 mm, and then dry it in a drying tunnel at 140°C and 12 m in length at a speed of 3 m / min. After removing the fluoroPET release film, rewind it once to obtain the final product.

[0125] Example 5

[0126] The first aspect of this example provides a high-strength, substrate-free thermally conductive insulating sheet, the raw materials for which, by mass parts, include: 19 parts silicone oil, 210 parts thermally conductive filler, 0.6 parts dispersant, and 15 parts diluent.

[0127] The thermally conductive filler, by weight, comprises 60 parts of spherical thermally conductive filler and 150 parts of near-spherical thermally conductive filler.

[0128] The spherical thermally conductive filler comprises: spherical alumina with a particle size of 10 μm and spherical boron nitride with a particle size of 5 μm, with a mass ratio of 14:1 between the two components.

[0129] The spherical thermally conductive filler comprises spherical alumina with a particle size of 1 μm and spherical zinc oxide with a particle size of 0.2 μm, with a mass ratio of 2:1 between the two components.

[0130] Among them, the spherical alumina with a particle size of 10μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: SHA-10.

[0131] Spherical boron nitride with a particle size of 5μm was purchased from Sichuan Ya'an Baitu High-Tech Materials Co., Ltd., model: PBN-5.

[0132] Spherical alumina with a particle size of 1μm was purchased from Sichuan Ya'an Baitu High-Tech Materials Co., Ltd., model: Bak-1.

[0133] Spherical zinc oxide with a particle size of 0.2 μm was purchased from Horsehead, USA, model: Kadox 911.

[0134] The silicone oil is a vinyl silicone oil with a viscosity of 100,000 mPa·s and a vinyl content of 0.3 mol%, model RH-Vi301, purchased from Ningbo Runhe High-tech Materials Technology Co., Ltd.

[0135] The dispersant is dodecyltriethoxysilane.

[0136] The diluent is petroleum ether.

[0137] The second aspect of this example provides a method for preparing a high-strength, substrate-free thermally conductive insulating sheet, including:

[0138] S1. Place the thermally conductive filler in a vacuum drying oven and mix evenly. Bake at 190°C for 4 hours, then let it cool naturally to 25°C.

[0139] S2. Add dispersant to the thermally conductive filler obtained in step S1, mix evenly, place in a vacuum drying oven, bake at 120℃ for 2 hours, and then cool naturally to 25℃ to obtain the base material;

[0140] S3. Add silicone oil to the base material obtained in step S2, mix evenly, add diluent, mix evenly, degas under a pressure of -0.1MPa for 40 minutes, and package to obtain the semi-finished product.

[0141] S4. Place the semi-finished product obtained in step S3 onto a fluoroPET release film, coat it with a coating blade to a thickness of 0.2 mm, and then dry it in a drying tunnel at 130°C and 12 m in length at a speed of 2 m / min. After removing the fluoroPET release film, rewind it once to obtain the final product.

[0142] Example 6

[0143] The first aspect of this example provides a high-strength, substrate-free thermally conductive insulating sheet, the raw materials for which, by mass, include: 20 parts silicone oil, 170 parts thermally conductive filler, 0.7 parts dispersant, and 20 parts diluent.

[0144] The thermally conductive filler, by mass fraction, comprises 47 parts spherical thermally conductive filler and 123 parts near-spherical thermally conductive filler.

[0145] The spherical thermally conductive filler comprises: spherical alumina with a particle size of 3 μm and spherical boron nitride with a particle size of 5 μm, with a mass ratio of 40:1 between the two components.

[0146] The spherical thermally conductive filler comprises spherical alumina with a particle size of 0.6 μm and spherical zinc oxide with a particle size of 0.2 μm, with a mass ratio of 30:17 between the two components.

[0147] Among them, the spherical alumina with a particle size of 3μm was purchased from Sumitomo Corporation of Japan, model: AA-3.

[0148] Spherical boron nitride with a particle size of 5μm was purchased from Sichuan Ya'an Baitu High-Tech Materials Co., Ltd., model: ABN-5.

[0149] Spherical alumina with a particle size of 0.6 μm was purchased from Sichuan Ya'an Baitu High-Tech Materials Co., Ltd., model: NSM1S.

[0150] Spherical zinc oxide with a particle size of 0.2 μm was purchased from Horsehead, USA, model: Kadox 911.

[0151] The silicone oil is a vinyl silicone oil with a viscosity of 15000 mPa·S, a vinyl content of 0.43 mol%, and a model number of SY-15000. It was purchased from Ningbo Daoruo Silicone Co., Ltd.

[0152] The dispersant is a modified organosilicon, model UM-5171, purchased from Wuhan Anruike Materials Co., Ltd.

[0153] The diluent is toluene.

[0154] The second aspect of this example provides a method for preparing a high-strength, substrate-free thermally conductive insulating sheet, including:

[0155] S1. Place the thermally conductive filler in a vacuum drying oven and mix evenly. Bake at 150°C for 8 hours, then let it cool naturally to 25°C.

[0156] S2. Add dispersant to the thermally conductive filler obtained in step S1, mix evenly, place in a vacuum drying oven, bake at 120℃ for 0.5h, and then cool naturally to 25℃ to obtain the base material;

[0157] S3. Add silicone oil to the base material obtained in step S2, mix evenly, add diluent, mix evenly, degas under a pressure of -0.1MPa for 40 minutes, and package to obtain the semi-finished product.

[0158] S4. Place the semi-finished product obtained in step S3 onto a fluoroPET release film, coat it with a coating blade to a thickness of 0.2 mm, and then dry it at a speed of 1 m / min through a drying tunnel with a temperature of 170°C and a length of 14 m. After removing the fluoroPET release film, rewind it once to obtain the final product.

[0159] Comparative Example 2

[0160] The first aspect of this example provides a high-strength, substrate-free thermally conductive insulating sheet, the raw materials for which, by mass, include: 12 parts silicone oil, 175 parts thermally conductive filler, 0.3 parts dispersant, and 5 parts diluent.

[0161] The thermally 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, in a weight ratio of 130:30:15.

[0162] Among them, the spherical alumina with a particle size of 10μm was purchased from Sichuan Ya'an Baitu High-tech Materials Co., Ltd., model: Bak-10.

[0163] Spherical alumina with a particle size of 2μm was purchased from: Chalco Shanxi New Materials Co., Ltd., model: ASF-2.

[0164] Spherical alumina with a particle size of 0.5 μm was purchased from Sumitomo Corporation, Japan, model number AA-05.

[0165] The silicone oil is a vinyl silicone oil with a viscosity of 10000 mPa·S, a vinyl content of 0.7 mol%, and a model number of SY-10000. It was purchased from Ningbo Daoruo Silicone Co., Ltd.

[0166] The dispersant is hexadecyltriethoxysilane.

[0167] The diluent is toluene.

[0168] The second aspect of this example provides a method for preparing a high-strength, substrate-free thermally conductive insulating sheet, including:

[0169] S1. Place the thermally conductive filler in a vacuum drying oven and mix evenly. Bake at 200℃ for 6 hours, then let it cool naturally to 25℃.

[0170] S2. Add dispersant to the thermally conductive filler obtained in step S1, mix evenly, place in a vacuum drying oven, bake at 120℃ for 0.5h, and then cool naturally to 25℃ to obtain the base material;

[0171] S3. Add silicone oil to the base material obtained in step S2, mix evenly, add diluent, mix evenly, degas under a pressure of -0.1MPa for 30 minutes, and package to obtain the semi-finished product;

[0172] S4. Place the semi-finished product obtained in step S3 onto a fluoroPET release film, coat it with a coating blade to a thickness of 0.2 mm, and then dry it in a drying tunnel at 120°C and 12 m in length at a speed of 1 m / min. After removing the fluoroPET release film, rewind it once to obtain the final product.

[0173] Performance Evaluation

[0174] 1. Thickness: Refer to ASTM D374 to test the thickness of the thermally conductive insulating sheets prepared in Examples 1-6 and Comparative Examples 1-2.

[0175] 2. Contact thermal resistance: Refer to ASTM 5470 to test the contact thermal resistance of the thermally conductive insulating sheets prepared in Examples 1-6 and Comparative Examples 1-2.

[0176] 3. Thermal conductivity: The thermal conductivity of the thermally conductive insulating sheets prepared in Examples 1-6 and Comparative Examples 1-2 was tested in accordance with ISO 22007-2.

[0177] 4. Breakdown voltage: Refer to ASTM D149 to test the breakdown voltage of the thermally conductive insulating sheets prepared in Examples 1-6 and Comparative Examples 1-2.

[0178] The test results for Experimental Group 1 are detailed in Table 1, and the test results for Experimental Group 2 are detailed in Table 2.

[0179] Table 1

[0180] Table 2

Claims

1. A high-strength, substrate-free thermally conductive insulating sheet, characterized in that, The raw materials for preparation, by mass, include: 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 3 W / m·k, and the tensile strength is greater than 3 MPa.

2. The high-strength substrate-free thermally conductive insulating sheet according to claim 1, characterized in that, The 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 spherical thermally conductive filler and near-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 thermal conductive filler to the near-spherical thermal 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 spherical thermally conductive filler has a particle size of 0.2-10 μm, and the near-spherical thermally conductive filler has a particle size of 0.3-34 μm.

8. The high-strength substrate-free thermally conductive insulating sheet according to claim 5, characterized in that, The spherical thermally conductive filler includes one or more of the following: 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 thermally conductive filler includes one or more of the following: spherical alumina, 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 includes at least one of the following: modified organosilicon, titanate, stearic acid, aluminate, silane coupling agent, pentaerythritol ester, and acrylate leveling agent.

10. A method for preparing a high-strength substrate-free thermally conductive insulating sheet, said preparation method being based on the high-strength substrate-free thermally conductive insulating sheet according to any one of claims 1-9, characterized in that, include: S1. Place the thermally conductive filler in a vacuum drying oven and mix evenly. Bake at 150-210℃ for 4-8 hours, then cool naturally to 25-30℃. S2. Add dispersant to the thermally conductive filler obtained in step S1, mix evenly, place in a vacuum drying oven, bake at 80-120℃ for 0.5-2 hours, and then cool naturally to 25-30℃ to obtain the base material; S3. Add silicone oil to the base material and mix evenly to obtain a semi-finished product; S4. The semi-finished product is subjected to a calendering process. The bottom film is a release film and the top film is a release film. After being calendered by two rollers and dried in an oven tunnel, the bottom film and the top film are removed and then rewound to obtain the high-strength, substrate-free thermally conductive insulating sheet.

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