Low-thermal-resistance heat-conducting silica gel sheet material and preparation method thereof

Abstract

The invention belongs to the technical field of heat-conducting silica gel, and particularly relates to a low-heat-resistance heat-conducting silica gel sheet material and a preparation method thereof.The low-heat-resistance heat-conducting silica gel sheet material comprises a heat-conducting layer and a release film layer covering the surface of the heat-conducting layer, and the heat-conducting layer comprises a sheet-shaped heat-conducting layer and a paste-shaped heat-conducting layer arranged between the sheet-shaped heat-conducting layer and the release film layer. The heat-conducting layer is prepared from the following components in parts by weight: 4 to 25 parts of vinyl silicone oil, 74 to 95 parts of heat-conducting filler, 0.3 to 1.5 parts of side hydrogen-containing silicone oil, 0.3 to 1.5 parts of end hydrogen-containing silicone oil and 0.01 to 0.05 part of platinum catalyst; the surface, attached to the heat conduction layer, of the release film layer is treated with an alkaline solution. According to the silica gel sheet, the contact thermal resistance of the silica gel sheet is reduced while the original hardness of the silica gel sheet is kept, and the silica gel sheet has high hardness and high heat conduction efficiency.

Description

Technical Field

[0001] The 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 electronic equipment industry, thermally conductive silicone sheets are widely used as part of the heat sink, especially in high-performance electronic devices that are sensitive to temperature changes. There are many pores on the heat interface and the heat sink surface at the microscopic level. These pores increase the contact thermal resistance and affect the heat transfer. The thermally conductive silicone sheet fills the pores between the heat sink and the heat interface through a certain compression, which can effectively transfer heat from the chip surface to the larger heat sink or housing, thereby maintaining the stable operation of the device.

[0003] At present, the most common method for pursuing high heat dissipation efficiency of thermal conductive silicone sheets is to increase its thermal conductivity and reduce its hardness. Due to the high proportion of thermal conductive fillers in high thermal conductive silicone sheets, the compression modulus is reduced and it cannot efficiently fill the pores on the surface of the radiator. The contact thermal resistance with the heat sink will increase, which will reduce the thermal conductivity efficiency. By reducing the hardness of high thermal conductive silicone sheets, the compression modulus will increase, the contact surface filling will be better, and the thermal resistance will be reduced accordingly, but the overall strength of the material will also be reduced, making it easy to break and deform. 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 invention object, the technical solution adopted by the present invention is as follows: On one hand, the present invention provides a low thermal resistance thermally conductive silicone sheet material, which includes a thermally conductive layer and a release film layer covering the surface of the thermally conductive layer, wherein the thermally conductive layer includes a sheet-like thermally conductive layer and a paste-like thermally conductive layer arranged between the sheet-like thermally conductive layer and the release film layer.

[0007] 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 that is bonded to the heat-conducting layer is treated with an alkaline solution.

[0008] Wherein, the vinyl silicone oil is vinyl-terminated polydimethylsiloxane, and the viscosity of the vinyl silicone oil is 300 Pa.s-5000 Pa.s.

[0009] Wherein, the thermally conductive filler is at least one of aluminum oxide, aluminum hydroxide, zinc oxide, boron nitride, aluminum nitride, silicon dioxide, and diamond.

[0010] Wherein, the particle size of the thermal conductive filler is 0.4-150 μm.

[0011] 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%.

[0012] 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%.

[0013] Wherein, the platinum catalyst is a Custer catalyst, and the Pt content is 1000ppm to 5000ppm.

[0014] Wherein, the alkaline solution is sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution, and the concentration of the alkaline solution is 0.1%-1%.

[0015] 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: Step 1: Evenly mix vinyl silicone oil, thermal conductive filler, side hydrogen-containing silicone oil, end hydrogen-containing silicone oil, and platinum catalyst at room temperature to prepare a silicone sheet base material; Step 2: Applying an alkaline solution on the surface of the release film; Step 3: Cover the surface of the release film containing the alkaline solution on the surface 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 release film 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.

[0016] Wherein, in step 4, the heating and curing temperature is 120-140°C.

[0017] Beneficial effects of the present invention: The invention processes the surface of the silicone sheet, uses silicone resin and hydrogen-containing 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.

[0018] 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

[0019] 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 of the embodiments. In conjunction with the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without 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.

[0020] In the description of the present invention, the term "and / or" describes the association relationship of associated objects, indicating that three relationships may exist. For example, A and / or B can represent: A exists alone, A and B exist at the same time, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects before and after are in an "or" relationship.

[0021] In the description of the present 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 items 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 be single or multiple.

[0022] It should be understood that the weight of the relevant components mentioned in the embodiments of the present invention can not only refer to the specific content of each component, but also represent the proportional relationship between the weights of the components. Therefore, as long as the content of the relevant components in the embodiments of the present invention is proportionally enlarged or reduced, it is within the scope disclosed by the present invention. Specifically, the weight described in the embodiments of the present invention can be a mass unit known in the chemical industry such as μg, mg, g, kg, etc.

[0023] In addition, unless the context clearly uses otherwise, the expression of the singular form of a word should be understood to include the plural form of the word. The term "includes" or "having" is intended to specify the existence of a feature, quantity, step, operation, element, part or combination thereof, but is not used to exclude the existence or possible addition of one or more other features, quantities, steps, operations, elements, parts or combinations thereof.

[0024] An embodiment of the present invention provides a low thermal resistance thermally conductive silicone sheet material, which includes a thermally conductive layer and a release film layer covering the surface of the thermally conductive layer, wherein the thermally conductive layer includes a sheet-like thermally conductive layer and a paste-like thermally conductive layer arranged between the sheet-like thermally conductive layer and the release film layer.

[0025] 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.

[0026] The surface of the release film layer that is bonded to the heat-conducting layer is treated with an alkaline solution.

[0027] 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 comprises the above-mentioned components in parts by weight, the thermally conductive layer contains hydrogenated silicone oil, the surface where the release film layer and the thermally conductive layer are bonded is treated with an alkaline solution, the alkaline solution on the surface of the release film layer will react with the hydrogenated silicone oil on the surface of the thermally conductive layer, and then consume the hydrogenated silicone oil on the surface of the thermally conductive layer, so that the surface layer of the thermally conductive layer cannot be solidified, forming a paste-like thermally conductive layer, and the hydrogenated silicone oil located inside the thermally conductive layer does not contact and react with the alkaline solution, and still has high hardness after subsequent solidification. The thermally conductive silicone material of the present invention, under the condition of not reducing the hardness, has its surface covered with a paste-like thermally conductive layer similar to thermally conductive silicone grease, and this thermally conductive layer penetrates into the interface pores, which 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 the existing thermally conductive silicone sheets.

[0028] Wherein, the vinyl silicone oil is vinyl-terminated polydimethylsiloxane, and the viscosity of the vinyl silicone oil is 300 Pa.s-5000 Pa.s.

[0029] Wherein, the thermally conductive filler is at least one of aluminum oxide, aluminum hydroxide, zinc oxide, boron nitride, aluminum nitride, silicon dioxide, and diamond.

[0030] Wherein, the particle size of the thermal conductive filler is 0.4-150 μm.

[0031] 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%.

[0032] 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%.

[0033] Wherein, the platinum catalyst is a Custer catalyst, and the Pt content is 1000ppm to 5000ppm.

[0034] Wherein, the alkaline solution is sodium hydroxide solution, potassium hydroxide solution, calcium hydroxide solution, and the concentration of the alkaline solution is 0.1%-1%.

[0035] The thermal conductive layer further comprises 0.01-0.05 parts by weight of a colorant, wherein the colorant is a filler having a coloring effect, specifically at least one of carbon black, black ferroferric oxide, red iron oxide, and mica iron oxide gray.

[0036] The method for preparing the above-mentioned low thermal resistance thermal conductive silicone sheet material comprises the following preparation steps: Step 1: Evenly mix vinyl silicone oil, thermal conductive filler, side hydrogen-containing silicone oil, end hydrogen-containing silicone oil, and platinum catalyst at room temperature to prepare a silicone sheet base material; Step 2: Applying an alkaline solution on the surface of the release film; Step 3: Cover the surface of the release film containing the alkaline solution on the surface 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 release film 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.

[0037] The present invention first mixes the raw material components to obtain a silicone base material, then covers the release film coated with an alkaline solution on the surface of the silicone base material, and then calenders it into a sheet through a calender, and then stands at room temperature. During the standing process, the alkaline solution on the surface of the release film will react with the hydrogen-containing silicone oil on the surface of the flaky silicone base material, consume the hydrogen-containing silicone oil on the surface, so that the surface of the silicone base material attached to the release film cannot be cured, forming a paste, and then the semi-finished silicone sheet is heated and cured to formulate a low thermal resistance thermal conductive silicone sheet material. The surface of the obtained low thermal resistance thermal conductive silicone sheet attached to the release film is a paste, and the interior is a solid silicone thermal conductive layer. The paste thermal 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 silicone sheet, and the solid thermal conductive layer can keep the silicone sheet material of the present invention The original hardness, thereby realizing the reduction of the contact thermal resistance of the silicone sheet without reducing the hardness of the silicone sheet. The preparation method of the present invention adopts an integrated molding process, and the preparation method is simple, which is convenient for production and installation at the application end.

[0038] Among them, in step four, 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.

[0039] 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 by multiple embodiments below.

[0040] Example 1 A method for preparing a low thermal resistance thermally conductive silicone sheet material comprises the following preparation steps: Step 1: Take 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 by weight, mix the above components at room temperature and stir them evenly with a planetary mixer at a stirring speed of 2500r / min for 60min to prepare a silicone sheet base material; 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; Step 3: Cover the surface of the release film containing the alkaline solution on the surface 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 release film on the surface; Step 4: Leave the semi-finished silicone sheet at room temperature for 8 hours, then place 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.

[0041] Wherein, the vinyl silicone oil is vinyl-terminated polydimethylsiloxane with a viscosity of 300 Pa.s.

[0042] Wherein, the thermal conductive filler is aluminum oxide, and the particle size of the thermal conductive filler is 0.4 μm.

[0043] Wherein, the side chain hydrogen-containing silicone oil is a side chain hydrogen-containing silicone oil with a hydrogen content of 0.1%.

[0044] Wherein, the terminal hydrogen-containing silicone oil is a terminal chain hydrogen-containing silicone oil with a hydrogen content of 0.05%.

[0045] Wherein, the platinum catalyst is a Custer catalyst, and the Pt content is 1000ppm.

[0046] The prepared low thermal resistance thermally conductive silicone sheet material comprises a thermally conductive layer and a release film layer covering the surface of the thermally conductive layer, wherein the thermally conductive layer comprises a sheet-like thermally conductive layer and a paste-like thermally conductive layer arranged between the sheet-like thermally conductive layer and the release film layer, and the thickness of the thermally conductive layer is 1 mm.

[0047] Example 2 A method for preparing a low thermal resistance thermally conductive silicone sheet material comprises the following preparation steps: Step 1: Take 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 by weight, mix the above components at room temperature and stir them evenly with a planetary mixer at a stirring speed of 2500r / min for 60min to prepare a silicone sheet base material; 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; Step 3: Cover the surface of the release film containing the alkaline solution on the surface 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 release film on the surface; Step 4: Leave the semi-finished silicone sheet at room temperature for 10 hours, then place 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.

[0048] Wherein, the vinyl silicone oil is vinyl-terminated polydimethylsiloxane with a viscosity of 2500 Pa.s.

[0049] Wherein, the thermally conductive filler is aluminum hydroxide, and the particle size of the thermally conductive filler is 75 μm.

[0050] Wherein, the side chain hydrogen-containing silicone oil is a side chain hydrogen-containing silicone oil with a hydrogen content of 0.3%.

[0051] Wherein, the terminal hydrogen-containing silicone oil is a terminal chain hydrogen-containing silicone oil with a hydrogen content of 0.075%.

[0052] Wherein, the platinum catalyst is a Custer catalyst, and the Pt content is 3000ppm.

[0053] The prepared low thermal resistance thermally conductive silicone sheet material includes a thermally conductive layer and a release film layer covering the surface of the thermally conductive layer, the thermally conductive layer includes a sheet-like thermally conductive layer and a paste-like thermally conductive layer arranged between the sheet-like thermally conductive layer and the release film layer, and the thickness of the thermally conductive layer is 8 mm.

[0054] Example 3 A method for preparing a low thermal resistance thermally conductive silicone sheet material comprises the following preparation steps: Step 1: Take 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 by weight, mix the above components at room temperature and stir them evenly with a planetary mixer at a stirring speed of 2500r / min for 60min to prepare a silicone sheet base material; 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; Step 3: Cover the surface of the release film containing the alkaline solution on the surface 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 release film on the surface; Step 4: Leave the semi-finished silicone sheet at room temperature for 12 hours, then place 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.

[0055] Wherein, the vinyl silicone oil is vinyl-terminated polydimethylsiloxane with a viscosity of 5000 Pa.s.

[0056] Wherein, the thermal conductive filler is aluminum oxide, and the particle size of the thermal conductive filler is 150 μm.

[0057] Wherein, the side chain hydrogen-containing silicone oil is a side chain hydrogen-containing silicone oil with a hydrogen content of 0.5%.

[0058] Wherein, the terminal hydrogen-containing silicone oil is a terminal chain hydrogen-containing silicone oil with a hydrogen content of 0.1%.

[0059] Wherein, the platinum catalyst is a Custer catalyst, and the Pt content is 5000ppm.

[0060] The prepared low thermal resistance thermally conductive silicone sheet material comprises a thermally conductive layer and a release film layer covering the surface of the thermally conductive layer, wherein the thermally conductive layer comprises a sheet-like thermally conductive layer and a paste-like thermally conductive layer arranged between the sheet-like thermally conductive layer and the release film layer, and the thickness of the thermally conductive layer is 15 mm.

[0061] Example 4 A method for preparing a low thermal resistance thermally conductive silicone sheet material comprises the following preparation steps: Step 1: Take 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 hydrogen silicone oil, 0.3 parts of end hydrogen silicone oil, and 0.05 parts of platinum catalyst by weight, mix the above components at room temperature and stir them evenly with a planetary mixer at a stirring speed of 2500r / min for 60min to prepare a silicone sheet base material; 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; 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 release film on the surface; Step 4: Leave the semi-finished silicone sheet at room temperature for 10 hours, then place 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.

[0062] Wherein, the vinyl silicone oil is vinyl-terminated polydimethylsiloxane with a viscosity of 2500 Pa.s.

[0063] Wherein, the thermally conductive filler is aluminum hydroxide, and the particle size of the thermally conductive filler is 75 μm.

[0064] Wherein, the side chain hydrogen-containing silicone oil is a side chain hydrogen-containing silicone oil with a hydrogen content of 0.3%.

[0065] Wherein, the terminal hydrogen-containing silicone oil is a terminal chain hydrogen-containing silicone oil with a hydrogen content of 0.075%.

[0066] Wherein, the platinum catalyst is a Custer catalyst, and the Pt content is 3000ppm.

[0067] The prepared low thermal resistance thermally conductive silicone sheet material includes a thermally conductive layer and a release film layer covering two opposite surfaces of the thermally conductive layer, the thermally conductive layer includes a sheet-like thermally conductive layer and a paste-like thermally conductive layer arranged between the sheet-like thermally conductive layer and the release film layer. Specifically, the low thermal resistance thermally conductive silicone sheet material is sequentially provided with a first release film layer, a first paste-like thermally conductive layer, a sheet-like thermally conductive layer, a second paste-like thermally conductive layer and a second release film layer from top to bottom, and the thickness of the thermally conductive layer is 1 mm.

[0068] Example 5 Example 5 provides a method for preparing a low thermal resistance thermally 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 a release film containing an alkaline solution on one surface of a 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.

[0069] The other preparation steps of Example 5 are the same as those of Example 4 and are not described in detail here.

[0070] The low thermal resistance thermally conductive silicone sheet material obtained by the preparation method of Example 5 includes a thermally conductive layer and a release film layer covering the surface of the thermally conductive layer, the thermally conductive layer includes a sheet-like thermally conductive layer and a paste-like thermally conductive layer arranged between the sheet-like thermally conductive layer and the release film layer. Specifically, the low thermal resistance thermally conductive silicone sheet material is provided with a release film layer, a paste-like thermally conductive layer, and a sheet-like thermally conductive layer in sequence from top to bottom, and the thickness of the thermally conductive layer is 1 mm.

[0071] Comparative Example 1 A method for preparing a low thermal resistance thermally conductive silicone sheet material. The difference between the preparation method of comparative example 1 and that of embodiment 4 is that the release film of comparative example 1 is not treated with an alkaline solution.

[0072] The low thermal resistance thermally conductive silicone sheet material prepared in Comparative Example 1 comprises a thermally conductive layer and a release film layer covering the surface of the thermally conductive layer.

[0073] The other preparation steps of Comparative Example 1 are the same as those of Example 4 and are not described in detail here.

[0074] Comparative Example 2 A method for preparing a low thermal resistance thermal conductive silicone sheet material, the difference between the preparation method of comparative example 2 and that of embodiment 4 is that the weight portion of the side hydrogen-containing silicone oil added in comparative example 2 is 0.2 parts, and the weight portion of the end hydrogen-containing silicone oil added is 0.2 parts. The release film of comparative example 2 is not treated with an alkaline solution.

[0075] The low thermal resistance thermally conductive silicone sheet material prepared in Comparative Example 2 includes a thermally conductive layer and a release film layer covering the surface of the thermally conductive layer.

[0076] The other preparation steps of Comparative Example 2 are the same as those of Example 4 and are not described in detail here.

[0077] Performance Testing The thermal conductivity, thermal resistance, hardness and tensile strength of the low thermal resistance thermal conductive silicone sheet materials prepared in Examples 4-5 and Comparative Examples 1 and 2 were tested. Specifically, the thermal conductivity of the silicone sheet material was tested using a thermal conductivity tester according to the method specified in ASTM D5470, the thermal resistance of the silicone sheet material was tested using a material thermal resistance tester according to the method specified in ASTM D5470, the thickness of the silicone sheet material was measured using a thickness ruler or caliper according to the method specified in ASTM D374, the hardness of the silicone sheet material was measured using a Shore durometer according to the method specified in ASTM D2240, and the tensile strength of the silicone sheet material was tested using a universal material testing machine according to the method specified in ASTM D412. The test results are shown in the following table.

[0078] Table 2. Performance test results of low thermal resistance thermal conductive silicone sheet materials 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 HardnessShore OO 81 81 81 45 Tensile strength(MPa) 0.58 0.59 0.6 0.2 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 bonded to the release film treated with an alkaline solution, while only one surface of the silicone sheet material in Example 5 is bonded 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 a paste-like thermal conductive layer, and the silicone in the middle is cross-linked and solidified to form a solid sheet. The thermal conductive layer, the sheet-like thermal conductive layer allows 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, so as to 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 further, 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.

[0079] From the test results in the above table, it can be seen that 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, and the tensile strength of the silicone sheet prepared in Comparative Example 1 is higher than that of the present invention. The difference between the preparation method of Comparative Example 1 and the embodiment of the present invention is that Comparative Example 1 does not use a release film treated with an alkaline solution to treat the silicone sheet, and the silicone sheet prepared in Comparative Example 1 is in a completely cross-linked and cured state and does not contain a paste-like thermal conductive layer.

[0080] In summary, from the test results of Examples 4 and 5 and Comparative Example 1, it can be seen that the present invention uses a reasonable combination of silicone resin and hydrogen-containing silicone oil, uses a release film treated with an alkaline solution to treat the surface of the silicone sheet, and uses a calendering process 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.

[0081] The above-mentioned embodiments only express several implementation methods of the present invention, and the description thereof is relatively specific and detailed, but it cannot be understood as limiting the scope of the patent of the present invention. It should be pointed out that, for ordinary technicians in this field, several variations and improvements can be made without departing from the concept of the present invention, which all belong to the protection scope of the present invention. Therefore, the protection scope of the patent of the present invention shall be subject to the attached claims.

Claims

1. A low thermal resistance thermal conductive silicone sheet material, characterized in that: It includes a heat-conducting layer and a release film layer covering the surface of the heat-conducting layer, wherein the heat-conducting layer includes a sheet-like heat-conducting layer and a paste-like heat-conducting layer arranged 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 that is bonded to the heat-conducting layer is treated with an alkaline solution.

2. According to claim 1, a low thermal resistance thermal conductive silicone sheet material, 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 a sodium hydroxide solution, a potassium hydroxide solution, or a calcium hydroxide solution, and the concentration of the alkaline solution is 0.1%-1%.

9. A method for preparing a low thermal resistance thermally conductive silicone sheet material, characterized in that: The method comprises the following preparation steps: Step 1: Evenly mix vinyl silicone oil, thermal conductive filler, side hydrogen-containing silicone oil, end hydrogen-containing silicone oil, and platinum catalyst at room temperature to prepare a silicone sheet base material; Step 2: Applying an alkaline solution on the surface of the release film; Step 3: Cover the surface of the release film containing the alkaline solution on the surface 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 release film 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.

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