A low thermal resistance thermal conductive silicone sheet material and preparation method thereof

Abstract

The present invention belongs to the field of thermally conductive silicone technology, and in particular to a low thermal resistance thermally conductive silicone sheet material and a preparation method thereof, wherein the low thermal resistance thermally conductive silicone sheet material includes a heat-conducting layer and a release film layer covering the surface of the heat-conducting layer, and the heat-conducting layer includes a sheet-like heat-conducting layer and a paste-like heat-conducting layer provided between the sheet-like heat-conducting layer and the release film layer. The heat-conducting layer includes the following components in parts by weight: 4-25 parts of vinyl silicone oil, 74-95 parts of thermally conductive filler, 0.3-1.5 parts of side hydrogenated silicone oil, 0.3-1.5 parts of end hydrogenated silicone oil, and 0.01-0.05 parts of platinum catalyst; the surface of the release film layer bonded to the heat-conducting layer is treated with an alkaline solution. The silicone sheet of the present invention reduces the contact thermal resistance of the silicone sheet while maintaining the original hardness of the silicone sheet, and has high hardness and high thermal conductivity.

Description

Technical Field

[0001] The present invention belongs to the technical field of thermal conductive silicone rubber, and in particular relates to a low thermal resistance thermal conductive silicone rubber sheet material and a preparation method thereof. Background Art

[0002] In the electronics industry, thermally conductive silicone sheets are widely used as part of heat sinks, especially in high-performance electronic devices that are sensitive to temperature fluctuations. At a microscopic level, the heat-generating interface and the heat sink surface contain numerous pores, which increase contact thermal resistance and affect heat transfer. Thermally conductive silicone sheets, through compression, fill these pores between the heat sink and the heat-generating interface, effectively transferring heat from the chip surface to a larger heat sink or housing, thereby maintaining stable device operation.

[0003] Currently, the most common method for achieving high heat dissipation efficiency with thermally conductive silicone sheets is to increase their thermal conductivity and reduce their hardness. However, due to the excessive proportion of thermally conductive filler in these sheets, their compression modulus is reduced, making them unable to effectively fill the pores on the heat sink surface. This increases the thermal contact resistance with the heat sink, which in turn reduces thermal conductivity. Reducing the hardness of these sheets increases the compression modulus, improving contact surface fill and reducing thermal resistance. However, this also reduces the overall strength of the material, making it more susceptible to breakage and deformation. Summary of the Invention

[0004] The first object of the present invention is to provide a low thermal resistance thermal conductive silicone sheet material, which maintains the original hardness of the silicone sheet while reducing the contact thermal resistance of the silicone sheet.

[0005] The second object of the present invention is to provide a method for preparing a low thermal resistance thermal conductive silicone sheet material, which adopts an integrated molding process to prepare a silicone sheet material with high hardness and high thermal conductivity efficiency.

[0006] In order to achieve the above-mentioned object of the invention, the technical solution adopted by the present invention is as follows:

[0007] On one hand, the present invention provides a low thermal resistance thermal conductive silicone sheet material, which includes a thermal conductive layer and a release film layer covering the surface of the thermal conductive layer. The thermal conductive layer includes a sheet-like thermal conductive layer and a paste-like thermal conductive layer arranged between the sheet-like thermal conductive layer and the release film layer.

[0008] The heat-conducting layer comprises the following components in parts by weight: 4-25 parts of vinyl silicone oil, 74-95 parts of heat-conducting filler, 0.3-1.5 parts of side hydrogen-containing silicone oil, 0.3-1.5 parts of end hydrogen-containing silicone oil, and 0.01-0.05 parts of platinum catalyst;

[0009] The surface of the release film layer in contact with the heat-conducting layer is treated with an alkaline solution.

[0010] Wherein, the vinyl silicone oil is vinyl-terminated polydimethylsiloxane, and the viscosity of the vinyl silicone oil is 300 Pa.s-5000 Pa.s.

[0011] Wherein, the thermal conductive filler is at least one of aluminum oxide, aluminum hydroxide, zinc oxide, boron nitride, aluminum nitride, silicon dioxide, and diamond.

[0012] Wherein, the particle size of the thermal conductive filler is 0.4-150 μm.

[0013] Wherein, the side chain hydrogen-containing silicone oil is a side chain hydrogen-containing silicone oil with a hydrogen content of 0.1% to 0.5%.

[0014] Wherein, the terminal hydrogen-containing silicone oil is a terminal chain hydrogen-containing silicone oil with a hydrogen content of 0.05% to 0.1%.

[0015] Wherein, the platinum catalyst is a Custer catalyst, and the Pt content is 1000ppm to 5000ppm.

[0016] Wherein, the alkaline solution is sodium hydroxide solution, potassium hydroxide solution, or calcium hydroxide solution, and the concentration of the alkaline solution is 0.1%-1%.

[0017] Another aspect of the present invention provides a method for preparing a low thermal resistance thermal conductive silicone sheet material, comprising the following preparation steps:

[0018] Step 1: Mix vinyl silicone oil, thermal conductive filler, side hydrogen silicone oil, end hydrogen silicone oil, and platinum catalyst at room temperature to prepare a silicone sheet base material;

[0019] Step 2: Applying alkaline solution on the surface of the release film;

[0020] Step 3: Covering the surface of the release film containing the alkaline solution on the surface of the silicone sheet base material, and using a calender to calender the silicone sheet base material into a sheet to obtain a semi-finished silicone sheet with the release film covered on the surface;

[0021] Step 4: Leave the semi-finished silicone sheet at room temperature for 8-12 hours, then heat and cure the semi-finished silicone sheet to obtain a low thermal resistance thermal conductive silicone sheet material.

[0022] Wherein, in step 4, the heating and curing temperature is 120-140°C.

[0023] Beneficial effects of the present invention:

[0024] The invention processes the surface of the silicone sheet, uses silicone resin and hydrogenated silicone oil in a reasonable combination, and adopts an improved calendering process to obtain a low-thermal-resistance silicone sheet with a solid interior and a paste-like surface.

[0025] The thermally conductive silicone sheet obtained by the method of the present invention has a thickness of 1-15 mm and a thermal conductivity of 1-8.0 W / m·K, and is very suitable for the field of mid-to-high-end electronic equipment, especially for filling and heat dissipation of precision electronic equipment. DETAILED DESCRIPTION

[0026] In order to make the purpose, technical scheme and technical effect of the embodiments of the present invention clearer, the technical scheme in the embodiments of the present invention is clearly and completely described. The embodiments described below are part of the embodiments of the present invention, rather than all the embodiments. In combination with the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative work are within the scope of protection of the present invention. If the specific conditions are not specified in the embodiments, they are carried out according to conventional conditions or the conditions recommended by the manufacturer; if the manufacturer of the reagents or instruments is not specified, they are all conventional products that can be purchased commercially.

[0027] In the present description, the term "and / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0028] In the description of this invention, "at least one" means one or more, and "plurality" means two or more. "At least one of the following" or similar expressions refers to any combination of these items, including any combination of single or plural items. For example, "at least one of a, b, or c" or "at least one of a, b and c" can all mean: a, b, c, ab (i.e., a and b), ac, bc, or abc, where a, b, and c can each be single or plural.

[0029] It should be understood that the weights of the relevant components mentioned in the embodiments of the present invention may not only refer to the specific content of each component, but also represent the weight ratio between the components. Therefore, as long as the content of the relevant components is proportionally increased or decreased according to the embodiments of the present invention, it is within the scope of the present invention. Specifically, the weights described in the embodiments of the present invention may be mass units known in the chemical industry, such as μg, mg, g, and kg.

[0030] In addition, unless the context clearly requires otherwise, expressions in the singular form of a word should be understood to include the plural form of the word. The terms "include" or "have" are intended to specify the presence of a feature, number, step, operation, element, part, or combination thereof, but are not used to exclude the presence or possibility of adding one or more other features, numbers, steps, operations, elements, parts, or combinations thereof.

[0031] An embodiment of the present invention provides a low thermal resistance thermal conductive silicone sheet material, which includes a thermal conductive layer and a release film layer covering the surface of the thermal conductive layer. The thermal conductive layer includes a sheet-like thermal conductive layer and a paste-like thermal conductive layer arranged between the sheet-like thermal conductive layer and the release film layer.

[0032] The heat-conducting layer comprises the following components in parts by weight: 4-25 parts of vinyl silicone oil, 74-95 parts of heat-conducting filler, 0.3-1.5 parts of side hydrogen-containing silicone oil, 0.3-1.5 parts of end hydrogen-containing silicone oil, and 0.01-0.05 parts of platinum catalyst.

[0033] The surface of the release film layer in contact with the heat-conducting layer is treated with an alkaline solution.

[0034] The low thermal resistance thermally conductive silicone sheet material of the present invention comprises a thermally conductive layer and a release film layer covering the surface of the thermally conductive layer, the thermally conductive layer comprising the above-mentioned components in parts by weight, the thermally conductive layer containing hydrogenated silicone oil, the surface of the release film layer bonded to the thermally conductive layer being treated with an alkaline solution, the alkaline solution on the surface of the release film layer reacting with the hydrogenated silicone oil on the surface of the thermally conductive layer, thereby consuming the hydrogenated silicone oil on the surface of the thermally conductive layer, making the surface layer of the thermally conductive layer unable to solidify, forming a paste-like thermally conductive layer, while the hydrogenated silicone oil located inside the thermally conductive layer does not react with the alkaline solution, and subsequently still has a high hardness after solidification. The thermally conductive silicone material of the present invention, without reducing the hardness, has its surface covered with a paste-like thermally conductive layer similar to thermally conductive silicone grease, the thermally conductive layer penetrating into the interface pores, can better fill the pores on the surface of the heat sink, thereby greatly reducing the contact thermal resistance of the silicone sheet, and solving the shortcomings of existing thermally conductive silicone sheets.

[0035] Wherein, the vinyl silicone oil is vinyl-terminated polydimethylsiloxane, and the viscosity of the vinyl silicone oil is 300 Pa.s-5000 Pa.s.

[0036] Wherein, the thermal conductive filler is at least one of aluminum oxide, aluminum hydroxide, zinc oxide, boron nitride, aluminum nitride, silicon dioxide, and diamond.

[0037] Wherein, the particle size of the thermal conductive filler is 0.4-150 μm.

[0038] Wherein, the side chain hydrogen-containing silicone oil is a side chain hydrogen-containing silicone oil with a hydrogen content of 0.1% to 0.5%.

[0039] Wherein, the terminal hydrogen-containing silicone oil is a terminal chain hydrogen-containing silicone oil with a hydrogen content of 0.05% to 0.1%.

[0040] Wherein, the platinum catalyst is a Custer catalyst, and the Pt content is 1000ppm to 5000ppm.

[0041] Wherein, the alkaline solution is sodium hydroxide solution, potassium hydroxide solution, or calcium hydroxide solution, and the concentration of the alkaline solution is 0.1%-1%.

[0042] The heat-conducting layer further comprises 0.01-0.05 parts by weight of a colorant, which is a filler having a coloring effect, specifically at least one of carbon black, ferroferric oxide black, red iron oxide, and mica iron oxide gray.

[0043] The method for preparing the above-mentioned low thermal resistance thermal conductive silicone sheet material comprises the following preparation steps:

[0044] Step 1: Mix vinyl silicone oil, thermal conductive filler, side hydrogen silicone oil, end hydrogen silicone oil, and platinum catalyst at room temperature to prepare a silicone sheet base material;

[0045] Step 2: Applying alkaline solution on the surface of the release film;

[0046] Step 3: Covering the surface of the release film containing the alkaline solution on the surface of the silicone sheet base material, and using a calender to calender the silicone sheet base material into a sheet to obtain a semi-finished silicone sheet with the release film covered on the surface;

[0047] Step 4: Leave the semi-finished silicone sheet at room temperature for 8-12 hours, then heat and cure the semi-finished silicone sheet to obtain a low thermal resistance thermal conductive silicone sheet material.

[0048] The present invention first mixes the raw material components to obtain a silica gel base material, then covers the release film coated with an alkaline solution on the surface of the silica gel base material, and then rolls it into a sheet by a calender, and then stands at room temperature. During the standing process, the alkaline solution on the surface of the release film reacts with the hydrogen-containing silicone oil on the surface of the flaky silica gel base material, consumes the hydrogen-containing silicone oil on the surface, and makes the surface of the silica gel base material adhered to the release film unable to solidify, forming a paste, and then the silica gel sheet semi-finished product is heated and solidified to formulate a low thermal resistance thermal conductive silica gel sheet material. The surface of the low thermal resistance thermal conductive silica gel sheet adhered to the release film is a paste, and the interior is a solid silica gel heat conductive layer. The paste heat conductive layer can penetrate into the interface pores and better fill the pores on the surface of the heat sink, thereby greatly reducing the contact thermal resistance of the silica gel sheet, and the solid heat conductive layer can keep the silica gel sheet material of the present invention original hardness, thereby achieving the reduction of the contact thermal resistance of the silica gel sheet without reducing the hardness of the silica gel sheet. The preparation method of the present invention adopts an integrated molding process, the preparation method is simple, and it is convenient for production and application end installation.

[0049] Among them, in step 4, the heating and curing temperature is 120-140°C, which can cross-link and cure the silicone inside the silicone base material, and finally obtain a thermally conductive silicone sheet with a paste-like surface and a solid interior.

[0050] In order to enable those skilled in the art to clearly understand the implementation details and operations of the present invention, and to significantly demonstrate the improved performance of the embodiments of the present invention, the above technical solutions are illustrated below through multiple embodiments.

[0051] Example 1

[0052] A method for preparing a low thermal resistance thermal conductive silicone sheet material, comprising the following preparation steps:

[0053] Step 1: 4 parts of vinyl silicone oil, 0.01 parts of carbon black colorant, 74 parts of thermal conductive filler, 0.3 parts of side hydrogenated silicone oil, 0.3 parts of end hydrogenated silicone oil, and 0.01 parts of platinum catalyst were mixed at room temperature and stirred evenly with a planetary mixer at a stirring speed of 2500 r / min for 60 minutes to prepare a silicone sheet base material;

[0054] Step 2: Applying a 0.1% sodium hydroxide alkaline solution on the surface of the release film to obtain a release film treated with an alkaline solution;

[0055] Step 3: Covering the surface of the release film containing the alkaline solution on the surface of the silicone sheet base material, and using a calender to calender the silicone sheet base material into a sheet to obtain a semi-finished silicone sheet with the release film covered on the surface;

[0056] Step 4: Let the semi-finished silicone sheet stand at room temperature for 8 hours, then put the semi-finished silicone sheet into an oven at 120°C for heating and curing for 20 minutes to obtain a low thermal resistance thermal conductive silicone sheet material.

[0057] Wherein, the vinyl silicone oil is vinyl-terminated polydimethylsiloxane with a viscosity of 300 Pa.s.

[0058] Wherein, the thermal conductive filler is aluminum oxide, and the particle size of the thermal conductive filler is 0.4 μm.

[0059] Wherein, the side chain hydrogen-containing silicone oil is a side chain hydrogen-containing silicone oil with a hydrogen content of 0.1%.

[0060] Wherein, the terminal hydrogen-containing silicone oil is a terminal chain hydrogen-containing silicone oil with a hydrogen content of 0.05%.

[0061] Wherein, the platinum catalyst is a Custer catalyst, and the Pt content is 1000ppm.

[0062] The prepared low thermal resistance thermal conductive silicone sheet material includes a thermal conductive layer and a release film layer covering the surface of the thermal conductive layer. The thermal conductive layer includes a sheet-like thermal conductive layer and a paste-like thermal conductive layer arranged between the sheet-like thermal conductive layer and the release film layer. The thickness of the thermal conductive layer is 1 mm.

[0063] Example 2

[0064] A method for preparing a low thermal resistance thermal conductive silicone sheet material, comprising the following preparation steps:

[0065] Step 1: 14.5 parts of vinyl silicone oil, 0.03 parts of carbon black colorant, 84.5 parts of thermal conductive filler, 0.9 parts of side hydrogen silicone oil, 0.9 parts of end hydrogen silicone oil, and 0.03 parts of platinum catalyst are taken by weight, and the above components are mixed at room temperature and stirred evenly using a planetary mixer at a stirring speed of 2500 r / min for 60 minutes to prepare a silicone sheet base material;

[0066] Step 2: Applying a 0.5% sodium hydroxide alkaline solution on the surface of the release film to obtain a release film treated with an alkaline solution;

[0067] Step 3: Covering the surface of the release film containing the alkaline solution on the surface of the silicone sheet base material, and using a calender to calender the silicone sheet base material into a sheet to obtain a semi-finished silicone sheet with the release film covered on the surface;

[0068] Step 4: Let the semi-finished silicone sheet stand at room temperature for 10 hours, then put the semi-finished silicone sheet into an oven at 130°C for heating and curing for 20 minutes to obtain a low thermal resistance thermal conductive silicone sheet material.

[0069] Wherein, the vinyl silicone oil is vinyl-terminated polydimethylsiloxane with a viscosity of 2500 Pa.s.

[0070] Wherein, the thermal conductive filler is aluminum hydroxide, and the particle size of the thermal conductive filler is 75 μm.

[0071] Wherein, the side chain hydrogen-containing silicone oil is a side chain hydrogen-containing silicone oil with a hydrogen content of 0.3%.

[0072] Wherein, the terminal hydrogen-containing silicone oil is a terminal chain hydrogen-containing silicone oil with a hydrogen content of 0.075%.

[0073] Wherein, the platinum catalyst is a Custer catalyst, and the Pt content is 3000ppm.

[0074] The prepared low thermal resistance thermal conductive silicone sheet material includes a thermal conductive layer and a release film layer covering the surface of the thermal conductive layer. The thermal conductive layer includes a sheet-like thermal conductive layer and a paste-like thermal conductive layer arranged between the sheet-like thermal conductive layer and the release film layer. The thickness of the thermal conductive layer is 8 mm.

[0075] Example 3

[0076] A method for preparing a low thermal resistance thermal conductive silicone sheet material, comprising the following preparation steps:

[0077] Step 1: 25 parts of vinyl silicone oil, 0.05 parts of carbon black colorant, 95 parts of thermal conductive filler, 1.5 parts of side hydrogenated silicone oil, 1.5 parts of end hydrogenated silicone oil, and 0.05 parts of platinum catalyst were mixed at room temperature and stirred evenly with a planetary mixer at a stirring speed of 2500 r / min for 60 minutes to prepare a silicone sheet base material;

[0078] Step 2: Applying a 1% sodium hydroxide alkaline solution on the surface of the release film to obtain a release film treated with an alkaline solution;

[0079] Step 3: Covering the surface of the release film containing the alkaline solution on the surface of the silicone sheet base material, and using a calender to calender the silicone sheet base material into a sheet to obtain a semi-finished silicone sheet with the release film covered on the surface;

[0080] Step 4: Let the semi-finished silicone sheet stand at room temperature for 12 hours, then put the semi-finished silicone sheet into an oven at 140°C for heating and curing for 20 minutes to obtain a low thermal resistance thermal conductive silicone sheet material.

[0081] Wherein, the vinyl silicone oil is vinyl-terminated polydimethylsiloxane with a viscosity of 5000 Pa.s.

[0082] Wherein, the thermal conductive filler is aluminum oxide, and the particle size of the thermal conductive filler is 150 μm.

[0083] Wherein, the side chain hydrogen-containing silicone oil is a side chain hydrogen-containing silicone oil with a hydrogen content of 0.5%.

[0084] Wherein, the terminal hydrogen-containing silicone oil is a terminal chain hydrogen-containing silicone oil with a hydrogen content of 0.1%.

[0085] Wherein, the platinum catalyst is a Custer catalyst, and the Pt content is 5000ppm.

[0086] The prepared low thermal resistance thermal conductive silicone sheet material includes a thermal conductive layer and a release film layer covering the surface of the thermal conductive layer. The thermal conductive layer includes a sheet-like thermal conductive layer and a paste-like thermal conductive layer arranged between the sheet-like thermal conductive layer and the release film layer. The thickness of the thermal conductive layer is 15 mm.

[0087] Example 4

[0088] A method for preparing a low thermal resistance thermal conductive silicone sheet material, comprising the following preparation steps:

[0089] Step 1: 4.8 parts of vinyl silicone oil, 0.05 parts of carbon black colorant, 94.5 parts of thermal conductive filler, 0.3 parts of side hydrogenated silicone oil, 0.3 parts of end hydrogenated silicone oil, and 0.05 parts of platinum catalyst were mixed at room temperature and stirred evenly with a planetary mixer at a stirring speed of 2500 r / min for 60 minutes to prepare a silicone sheet base material;

[0090] Step 2: Applying a 0.5% sodium hydroxide alkaline solution on the surface of the release film to obtain a release film treated with an alkaline solution;

[0091] Step 3: Cover the surface of the release film containing the alkaline solution on two opposite surfaces of the silicone sheet base material, and use a calender to calender the silicone sheet base material into a sheet to obtain a semi-finished silicone sheet with the surface covered with the release film;

[0092] Step 4: Let the semi-finished silicone sheet stand at room temperature for 10 hours, then put the semi-finished silicone sheet into an oven at 130°C for heating and curing for 20 minutes to obtain a low thermal resistance thermal conductive silicone sheet material.

[0093] Wherein, the vinyl silicone oil is vinyl-terminated polydimethylsiloxane with a viscosity of 2500 Pa.s.

[0094] Wherein, the thermal conductive filler is aluminum hydroxide, and the particle size of the thermal conductive filler is 75 μm.

[0095] Wherein, the side chain hydrogen-containing silicone oil is a side chain hydrogen-containing silicone oil with a hydrogen content of 0.3%.

[0096] Wherein, the terminal hydrogen-containing silicone oil is a terminal chain hydrogen-containing silicone oil with a hydrogen content of 0.075%.

[0097] Wherein, the platinum catalyst is a Custer catalyst, and the Pt content is 3000ppm.

[0098] The prepared low thermal resistance thermal conductive silicone sheet material includes a thermal conductive layer and a release film layer covering two opposite surfaces of the thermal conductive layer. The thermal conductive layer includes a sheet-shaped thermal conductive layer and a paste-shaped thermal conductive layer arranged between the sheet-shaped thermal conductive layer and the release film layer. Specifically, the low thermal resistance thermal conductive silicone sheet material is sequentially provided with a first release film layer, a first paste-shaped thermal conductive layer, a sheet-shaped thermal conductive layer, a second paste-shaped thermal conductive layer and a second release film layer from top to bottom. The thickness of the thermal conductive layer is 1 mm.

[0099] Example 5

[0100] Example 5 provides a method for preparing a low thermal resistance thermal conductive silicone sheet material. The difference between the preparation method of Example 5 and Example 4 is that step three of Example 5 is: covering the surface of the release film containing the alkaline solution on one surface of the silicone sheet base material, and using a calender to calender the silicone sheet base material into a sheet to obtain a silicone sheet semi-finished product with a surface covered with a release film.

[0101] The other preparation steps of Example 5 are the same as those of Example 4 and are not described in detail here.

[0102] The low thermal resistance thermal conductive silicone sheet material obtained by the preparation method of Example 5 includes a thermal conductive layer and a release film layer covering the surface of the thermal conductive layer, the thermal conductive layer includes a sheet-like thermal conductive layer and a paste-like thermal conductive layer arranged between the sheet-like thermal conductive layer and the release film layer. Specifically, the low thermal resistance thermal conductive silicone sheet material is sequentially provided with a release film layer, a paste-like thermal conductive layer, and a sheet-like thermal conductive layer from top to bottom, and the thickness of the thermal conductive layer is 1 mm.

[0103] Comparative Example 1

[0104] A method for preparing a low thermal resistance thermally conductive silicone sheet material. The difference between the preparation method of Comparative Example 1 and Example 4 is that the release film of Comparative Example 1 is not treated with an alkaline solution.

[0105] The low thermal resistance thermal conductive silicone sheet material prepared in Comparative Example 1 includes a thermal conductive layer and a release film layer covering the surface of the thermal conductive layer.

[0106] The other preparation steps of Comparative Example 1 are the same as those of Example 4 and are not described in detail here.

[0107] Comparative Example 2

[0108] A method for preparing a low thermal resistance thermally conductive silicone sheet material. The preparation method of Comparative Example 2 differs from that of Example 4 in that the amount of side hydrogen-containing silicone oil added in Comparative Example 2 is 0.2 parts by weight, and the amount of end hydrogen-containing silicone oil added is 0.2 parts by weight. The release film of Comparative Example 2 is not treated with an alkaline solution.

[0109] The low thermal resistance thermal conductive silicone sheet material prepared in Comparative Example 2 includes a thermal conductive layer and a release film layer covering the surface of the thermal conductive layer.

[0110] The other preparation steps of Comparative Example 2 are the same as those of Example 4 and are not described in detail here.

[0111] Performance Testing

[0112] The thermal conductivity, thermal resistance, hardness, and tensile strength of the low-thermal-resistance thermally conductive silicone sheets prepared in Examples 4-5 and Comparative Examples 1 and 2 were tested. Specifically, the thermal conductivity of the silicone sheet was tested using a thermal conductivity tester according to ASTM D5470, the thermal resistance of the silicone sheet was tested using a material thermal resistance tester according to ASTM D5470, the thickness of the silicone sheet was measured using a thickness gauge or caliper according to ASTM D374, the hardness of the silicone sheet was measured using a Shore durometer according to ASTM D2240, and the tensile strength of the silicone sheet was tested using a universal materials testing machine according to ASTM D412. The test results are shown in the table below.

[0113] Table 2. Performance test results of low thermal resistance thermal conductive silicone sheet materials

[0114] Group Example 4 Example 5 Comparative Example 1 Comparative Example 2 Thickness (mm) 1.0 1.0 1.0 1.0 Thermal conductivity (W / mk) 6.2 6.2 6 6 Thermal resistance (℃·in2 / W) 0.1 0.12 0.21 0.13 Hardness Shore OO 81 81 81 45 Tensile strength (MPa) 0.58 0.59 0.6 0.2

[0115] From the test results in the above table, it can be seen that the silicone sheet materials prepared in Example 4 and Example 5 have the same thickness, thermal conductivity, hardness and tensile strength, but the thermal resistance of the silicone sheet material in Example 4 is lower than that of the silicone sheet material in Example 5. This is because during the preparation process, both surfaces of the silicone sheet material in Example 4 are attached to the release film treated with an alkaline solution, while only one surface of the silicone sheet material in Example 5 is attached to the release film treated with an alkaline solution, thereby making the upper and lower surfaces of the silicone sheet material prepared in Example 4 into paste-like thermal conductive layers, and the silicone in the middle undergoes cross-linking and solidification to form a solid sheet. The thermal conductive layer, the sheet-like thermal conductive layer enables the prepared silicone sheet material to maintain its original hardness, and the paste-like thermal conductive layers on the upper and lower surfaces enable the paste-like thermal conductive layers on the upper and lower surfaces of the silicone sheet to penetrate into the interface pores of the heat dissipation product when the silicone sheet material is used, better fill the pores on the surface of the heat dissipation product, thereby reducing the contact thermal resistance of the silicone sheet. The silicone sheet material prepared in Example 5 has only one surface as the paste-like thermal conductive layer, and thus, when used, only one surface of the silicone sheet has the paste-like thermal conductive layer that can penetrate into the interface pores of the heat dissipation product. Therefore, the thermal resistance of the silicone sheet of Example 4 is lower than that of the silicone sheet of Example 5.

[0116] As shown in the test results in the table above, the thermal conductivity of the silicone sheet prepared in Comparative Example 1 is lower than that of the silicone sheet of the present invention. The thermal resistance of the silicone sheet prepared in Comparative Example 1 is higher than that of the silicone sheet of the present invention. The hardness of the silicone sheet prepared in Comparative Example 1 is the same as that of the silicone sheet of the present invention. The tensile strength of the silicone sheet prepared in Comparative Example 1 is higher than that of the silicone sheet of the present invention. The difference between the preparation methods of Comparative Example 1 and the examples of the present invention is that the silicone sheet of Comparative Example 1 is not treated with a release film treated with an alkaline solution. The silicone sheet prepared in Comparative Example 1 is in a fully cross-linked and cured state and does not contain a paste-like thermal conductive layer.

[0117] In summary, from the test results of Examples 4 and 5 and Comparative Example 1, it can be seen that the present invention uses silicone resin and hydrogen-containing silicone oil in a reasonable combination, and uses a release film treated with an alkaline solution to treat the surface of the silicone sheet. At the same time, a calendering process is used to obtain a low thermal resistance silicone sheet with a solid interior and a paste-like surface. The preparation method of the present invention can reduce the thermal resistance of the silicone sheet and improve the thermal conductivity of the silicone sheet without reducing the hardness of the silicone sheet.

[0118] The above-described embodiments merely illustrate several implementations of the present invention, and while their descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the present invention. It should be noted that a person skilled in the art would be able to make numerous variations and improvements without departing from the spirit of the present invention, all of which fall within the scope of protection of the present invention. Therefore, the scope of protection of the present invention shall be determined by the appended claims.

Claims

1. A low thermal resistance thermal conductive silicone sheet material, characterized in that: The heat conducting layer comprises a heat conducting layer and a release film layer covering the surface of the heat conducting layer, wherein the heat conducting layer comprises a sheet-like heat conducting layer and a paste-like heat conducting layer provided between the sheet-like heat conducting layer and the release film layer; The heat-conducting layer comprises the following components in parts by weight: 4-25 parts of vinyl silicone oil, 74-95 parts of heat-conducting filler, 0.3-1.5 parts of side hydrogen-containing silicone oil, 0.3-1.5 parts of end hydrogen-containing silicone oil, and 0.01-0.05 parts of platinum catalyst; The surface of the release film layer and the heat conductive layer in contact with each other is treated with an alkaline solution; The method for preparing the low thermal resistance thermal conductive silicone sheet material comprises the following steps: Step 1: Mix vinyl silicone oil, thermal conductive filler, side hydrogen silicone oil, end hydrogen silicone oil, and platinum catalyst at room temperature to prepare a silicone sheet base material; Step 2: Applying alkaline solution on the surface of the release film; Step 3: Covering the surface of the release film containing the alkaline solution on the surface of the silicone sheet base material, and using a calender to calender the silicone sheet base material into a sheet to obtain a semi-finished silicone sheet with the release film covered on the surface; Step 4: Leave the semi-finished silicone sheet at room temperature for 8-12 hours, then heat and cure the semi-finished silicone sheet to obtain a low thermal resistance thermal conductive silicone sheet material.

2. The low thermal resistance thermal conductive silicone sheet material according to claim 1, characterized in that: The vinyl silicone oil is vinyl-terminated polydimethylsiloxane, and the viscosity of the vinyl silicone oil is 300 Pa.s-5000 Pa.s.

3. The low thermal resistance thermal conductive silicone sheet material according to claim 1, characterized in that: The thermally conductive filler is at least one of aluminum oxide, aluminum hydroxide, zinc oxide, boron nitride, aluminum nitride, silicon dioxide, and diamond.

4. The low thermal resistance thermal conductive silicone sheet material according to claim 1, characterized in that: The particle size of the thermal conductive filler is 0.4-150 μm.

5. The low thermal resistance thermal conductive silicone sheet material according to claim 1, characterized in that: The side chain hydrogen-containing silicone oil is a side chain hydrogen-containing silicone oil with a hydrogen content of 0.1% to 0.5%.

6. The low thermal resistance thermal conductive silicone sheet material according to claim 1, characterized in that: The terminal hydrogen-containing silicone oil is a terminal chain hydrogen-containing silicone oil with a hydrogen content of 0.05% to 0.1%.

7. The low thermal resistance thermal conductive silicone sheet material according to claim 1, characterized in that: The platinum catalyst is a Custer catalyst, and the Pt content is 1000ppm to 5000ppm.

8. The low thermal resistance thermal conductive silicone sheet material according to claim 1, characterized in that: The alkaline solution is sodium hydroxide solution, potassium hydroxide solution, or calcium hydroxide solution, and the concentration of the alkaline solution is 0.1%-1%.

9. The low thermal resistance thermal conductive silicone sheet material according to claim 1, characterized in that: In step 4, the heating and curing temperature is 120-140°C.