High-temperature-resistant and high-pressure-resistant automobile heat-conducting silica gel gasket with ultra-thin structure and preparation method thereof

Abstract

The invention relates to the technical field of automobile parts, in particular to a high-temperature-resistant and high-pressure-resistant heat-conducting silica gel gasket for an automobile PTC (Positive Temperature Coefficient) and a preparation method thereof. According to the ultrathin-structure high-temperature-resistant and high-pressure-resistant heat-conducting silica gel gasket for the automobile PTC, the heat-conducting silica gel gasket is composed of a first heat-conducting PI layer, a middle heat-conducting silica gel layer and a third heat-conducting PI layer, and the middle heat-conducting silica gel layer is arranged between the first heat-conducting PI layer and the third heat-conducting PI layer. The heat-conducting silica gel gasket disclosed by the invention has comprehensive properties such as excellent temperature resistance, pressure resistance, heat conductivity coefficient, volume resistivity and the like.

Description

Technical Field

[0001] The present invention relates to the technical field of automobile parts, and in particular to an ultra-thin, high-temperature and high-pressure resistant thermally conductive silicone gasket for automobiles and a preparation method thereof. Background Art

[0002] With the rapid development of the new energy vehicle industry, charging technology continues to innovate. Some new energy vehicles have reached megawatt-level charging power and charging voltages as high as 1000V. The rapid charging enabled by high power and high voltage causes a sharp rise in the temperature of related components. However, conventional thermally conductive silicone gaskets typically have a temperature resistance range of only -50°C to 200°C. While they can withstand transient temperatures of 250°C (5 minutes) or even 300°C (1 minute), they still cannot meet the long-term stable operation requirements of new energy vehicles under high-power charging conditions.

[0003] Furthermore, the breakdown voltage of common thermally conductive silicone gaskets is approximately 4.5kV / mm. For products with a thickness of less than 0.5mm, the withstand voltage range is less than 2kV / mm. To ensure product stability and longevity, the long-term operating voltage must be 50%-70% below the gasket's breakdown voltage. This makes it difficult for conventional silicone gaskets to meet the withstand voltage requirements of high-voltage environments.

[0004] Therefore, there is an urgent need to develop a thermally conductive silicone gasket that can adapt to high power and high voltage working conditions and has high temperature and high pressure resistance. Summary of the Invention

[0005] The purpose of the present invention is to provide an ultra-thin structure of a high-temperature and high-pressure resistant thermal conductive silicone gasket for automobiles and a preparation method thereof, so as to solve the problem that the existing ordinary thermal conductive silicone gaskets cannot meet the high power and high voltage requirements of new energy vehicles in terms of temperature resistance and pressure resistance.

[0006] According to the first aspect of the present invention, the present invention provides an ultra-thin structure, high-temperature and high-pressure resistant thermally conductive silicone gasket for automobiles, wherein the thermally conductive silicone gasket consists of a three-layer structure, comprising a first thermally conductive PI layer, an intermediate thermally conductive silicone layer, and a third thermally conductive PI layer. The intermediate thermally conductive silicone layer is disposed between the first thermally conductive PI layer and the third thermally conductive PI layer, and the intermediate thermally conductive silicone layer contains phenyl vinyl silicone oil.

[0007] In certain embodiments of the present invention, the thermal conductivity of the first thermally conductive PI layer and the third thermally conductive PI layer is 0.36 W / m·K or 0.6 W / m·K.

[0008] In certain embodiments of the present invention, the thickness of the first thermally conductive PI layer and the third thermally conductive PI layer is 0.038 mm or 0.050 mm.

[0009] In some embodiments of the present application, the intermediate heat-conducting silica gel layer has a thickness of 0.25-0.40 mm.

[0010] In some embodiments of the present application, the total thickness of the heat-conducting silica gel gasket can be controlled to be between 0.3 mm and 0.5 mm.

[0011] In some embodiments of the present application, the intermediate heat-conducting silica gel layer is prepared from phenyl vinyl silicone oil, hydrogen-containing silicone oil, platinum gold catalyst, silicon hydrogen addition reaction inhibitor, and heat-conducting powder.

[0012] Preferably, the silicon hydrogen addition reaction inhibitor is 1-ethynylcyclohexanol.

[0013] Preferably, the hydrogen-containing silicone oil includes end hydrogen-containing silicone oil and end-side hydrogen-containing silicone oil.

[0014] Preferably, the heat-conducting powder includes alumina of different particle size ratios, and can also include zinc oxide, aluminum nitride, boron nitride, etc., preferably a low-cost alumina solution. The main particle size ratio of the alumina is: 60%-70% of spherical alumina with a particle size of about 15 μm, as the main heat-conducting path, for providing a basic heat-conducting framework and reducing the viscosity of the system; 20%-30% of spherical alumina with a particle size of about 2 μm, as a void filling particle, for filling the gap between large particles, improving the bulk density, and densifying the heat-conducting network; and 10%-15% of submicron alumina with a particle size of about 100 nm, as an interface optimization particle, for covering the particle interface, reducing phonon scattering, and reducing the interface thermal resistance.

[0015] Preferably, the heat-conducting powder is alumina of different particle size ratios, and the alumina powder is pretreated with a silane coupling agent (such as KH550), and the addition amount of the silane coupling agent is 1.0%-1.5% of the total mass of the alumina, preferably 1.2%. The pretreatment causes the silane coupling agent to form a chemical bond with the alumina.

[0016] Preferably, for every 100 parts by weight of the heat-conducting powder, 5.0-6.5 parts of phenyl vinyl silicone oil, 0.40-0.50 parts of end hydrogen-containing silicone oil, and 0.25-0.35 parts of end-side hydrogen-containing silicone oil are added, as well as a catalytic amount of platinum gold catalyst and silicon hydrogen addition reaction inhibitor.

[0017] According to a second aspect of the present application, the present application provides a preparation method of a super-thin heat-conducting silica gel gasket for high-temperature and high-pressure automotive PTC, and the specific steps are as follows: 1. Calendering: placing the mixed heat-conducting silica gel between the upper and lower two layers of heat-conducting PI, and using a calendering machine to press it into a sheet structure with a thickness of 0.25-0.40 mm.

[0018] 2. Baking and curing: The sheet structure after calendering is sent to the drying oven for baking and curing, and finally an ultra-thin high temperature and high pressure resistant thermal conductive silicone gasket is obtained; the baking time is 20min-60min, preferably 40min; the drying oven temperature is 100-150℃, preferably 130℃.

[0019] Preferably, the thermally conductive silica gel is prepared by the following method: Powder pretreatment: Take thermal conductive powder, add silane coupling agent, put it into a blender and stir it to complete the pretreatment of the powder to prevent powder agglomeration; Dry mixing: the pretreated thermal conductive powder is placed in a blender and stirred until the powder is evenly mixed; preferably, the thermal conductive powder is placed in a blender and stirred at 80° C. for 40 minutes; Wet mixing: Add phenyl vinyl silicone oil, hydrogen silicone oil, platinum catalyst and inhibitor to the dry mixed powder, and mix in a blender at a mixing speed of 30-100 rpm until the materials are evenly mixed.

[0020] The present invention has the following beneficial effects 1. Excellent Temperature Resistance: The intermediate thermally conductive silicone layer of the thermally conductive silicone gasket prepared in this invention is made with phenyl vinyl silicone oil, which can operate stably and long-term in temperatures ranging from -70°C to 320°C, maintaining the material's thermal conductivity and physical properties (such as hardness and insulation). It can also withstand short-term high temperatures of 350°C for several minutes, and its low-temperature tolerance limit is as low as -70°C, making it suitable for use in environments with severe cold or rapid temperature fluctuations. The phenyl structure maintains flexibility at low temperatures, effectively preventing the risk of freeze cracking.

[0021] 2. Good pressure resistance: Through reasonable material selection and three-layer structure design (thermal conductive PI layer and thermal conductive silicone layer), the thermal conductive silicone gasket of the present invention still has excellent pressure resistance at ultra-thin thickness (0.3-0.5mm), and the breakdown field strength is significantly higher than that of conventional silicone gaskets.

[0022] 3. Highly efficient thermal conductivity: Alumina powders with different particle size ratios form a multi-level thermal network: 15μm spherical alumina forms the main thermal path, 2μm spherical particles fill the gaps, and 100nm submicron particles optimize the interfacial thermal resistance, raising the overall thermal conductivity to over 3.0W / m・K.

[0023] 4. Simple preparation process: Thermal conductive silicone adopts the "dry mixing-wet mixing" two-step method, the process parameters are controllable, suitable for industrial production, and the product performance consistency is high. BRIEF DESCRIPTION OF THE DRAWINGS

[0024] Figure 1 It is a process flow chart of the present invention.

[0025] Figure 2This is the appearance diagram of Example 1.

[0026] Figure 3 This is the appearance diagram of Example 2.

[0027] Figure 4 This is the appearance diagram of Example 3.

[0028] Figure 5 This is the appearance diagram of Comparative Example 1.

[0029] Figure 6 This is the appearance diagram of Comparative Example 2. DETAILED DESCRIPTION

[0030] In the present invention, the first and third of the first thermally conductive PI layer and the third thermally conductive PI layer are only used to distinguish the thermally conductive PI layers, that is, the thermally conductive silicone layer serves as an intermediate layer; optionally, the first thermally conductive PI layer and the third thermally conductive PI layer can be interchanged.

[0031] Technical terms As used in the present invention, PTC refers to the abbreviation of Positive Temperature Coefficient; As used in the present invention, the thermal conductive PI layer refers to the English abbreviation of the polyimide layer; As used in the present invention, “about” means within ±30% of the present numerical value range. For example, the particle size of the alumina powder can be within ±30%, ±20%, ±10% or ±5%, preferably within 10%.

[0032] Unless otherwise specified, the raw materials used in the present invention can be raw materials well known in the prior art, such as the materials used in the embodiments of the present invention: Phenyl vinyl silicone oil: Use DY-PV401 phenyl vinyl silicone oil with a viscosity of 500mPa·s from Dayi Chemical; End-hydrogenated silicone oil: Use Runhe Material's RH-H45 end-hydrogenated silicone oil; Side-chain hydrogenated silicone oil: Use RH-H33 side-chain hydrogenated silicone oil from Runhe Materials; Platinum catalyst: chloroplatinic acid-isopropyl alcohol solution (platinum content 0.5%) from Siyou New Materials is used; Hydrosilylation reaction inhibitor: YZJ-1 inhibitor from Siyou New Materials, i.e. 1-ethynylcyclohexanol, is used; Thermal conductive PI: DuPont KAPTON® polyimide film MT+ is selected.

[0033] Example 1: 1. Powder pretreatment: Weigh 65g of 15μm spherical alumina, 25g of 2μm spherical alumina, and 10g of 100nm submicron alumina, mix them evenly, add 1.2g of silane coupling agent KH550, and put them into a blender and stir for 30 minutes.

[0034] 2. Dry mixing: Stir the pretreated powder at 80°C for 40 minutes until it is uniform.

[0035] 3. Wet mixing: After dry mixing, add 5.50g of phenyl vinyl silicone oil, 0.41g of terminal hydrogen silicone oil, 0.29g of terminal side hydrogen silicone oil, 0.02g of platinum catalyst, and 0.01g of inhibitor, and mix at 30rpm.

[0036] 4. Calendering: Place the mixed thermally conductive silicone between the upper and lower layers of thermally conductive PI. The upper and lower layers use 0.36W / m・K, 0.038mm thermally conductive PI layers, and press them into a 0.25mm silicone layer.

[0037] 5. Baking and curing: Bake in a 130℃ oven for 40 minutes, total thickness 0.326mm.

[0038] Example 2: 1. Powder pretreatment: Weigh 60g of 15μm spherical alumina, 30g of 2μm quasi-spherical alumina, and 10g of 100nm submicron alumina, add 1.0g of KH550, and place in a blender and stir for 30min.

[0039] 2. Dry mixing: Stir the pretreated powder at 80°C for 40 minutes until it is uniform.

[0040] 3. Wet mixing: After dry mixing, add 6.12g of phenyl vinyl silicone oil, 0.43g of terminal hydrogen silicone oil, 0.31g of terminal side hydrogen silicone oil, 0.02g of platinum catalyst, and 0.01g of inhibitor, and mix at 50rpm.

[0041] 4. Calendering: Place the mixed thermally conductive silicone between the upper and lower layers of thermally conductive PI. The upper and lower layers use 0.6W / m・K, 0.05mm thermally conductive PI, and press them into a 0.40mm silicone layer.

[0042] 5. Baking and curing: baking at 120℃ for 60min, total thickness 0.5mm.

[0043] Example 3: 1. Powder pretreatment: Weigh 70g of 15μm spherical alumina, 20g of 2μm spherical alumina, and 10g of 100nm submicron alumina, add 1.1g of KH550, and put them into a blender and stir for 30min.

[0044] 2. Dry mixing: Stir the pretreated powder at 80°C for 40 minutes until it is uniform.

[0045] 3. Wet mixing: After dry mixing, add 5.84g of phenyl vinyl silicone oil, 0.41g of terminal hydrogen silicone oil, 0.29g of terminal side hydrogen silicone oil, 0.02g of platinum catalyst, and 0.01g of inhibitor, and mix at 80rpm.

[0046] 4. Calendering: Place the mixed thermally conductive silicone between the upper and lower layers of thermally conductive PI. Use 0.36W / m・K, 0.038mm thermally conductive PI for the upper layer and 0.6W / m・K, 0.05mm thermally conductive PI for the lower layer, and press them into a 0.30mm silicone layer.

[0047] 5. Baking and curing: Bake at 150℃ for 20 minutes, total thickness 0.388mm.

[0048] Comparative Example 1 (using methyl vinyl silicone oil) 1. Powder pretreatment: As in Example 1, weigh alumina powder with the same proportion and add 1.2g KH550 for pretreatment.

[0049] 2. Dry mixing: Same as Example 1.

[0050] 3. Wet mixing: replace phenyl vinyl silicone oil with methyl vinyl silicone oil, and use the same raw materials and amounts as in Example 1, and mix at a speed of 30 rpm.

[0051] 4. Calendering: Press the silicone into a silicone layer with a thickness of 0.326mm.

[0052] 5. Baking and curing: Same as Example 1, baking at 130°C for 40 min, total thickness 0.326 mm.

[0053] Comparative Example 2: 1. Powder pretreatment: Weigh 65g of 70μm spherical alumina, 25g of 40μm spherical alumina, and 10g of 20μm submicron alumina, mix them evenly, add 1.2g of silane coupling agent KH550, and put them into a blender and stir for 30 minutes.

[0054] 2. Dry mixing: Stir the pretreated powder at 80°C for 40 minutes until it is uniform.

[0055] 3. Wet mixing: After dry mixing, add 5.50g of phenyl vinyl silicone oil, 0.41g of terminal hydrogen silicone oil, 0.29g of terminal side hydrogen silicone oil, 0.02g of platinum catalyst, and 0.01g of inhibitor, and mix at 30rpm.

[0056] 4. Calendering: Place the mixed thermally conductive silicone between the upper and lower layers of thermally conductive PI. The upper and lower layers use 0.36W / m・K, 0.038mm thermally conductive PI layers, and press them into a 0.25mm silicone layer.

[0057] 5. Baking and curing: Bake in a 130℃ oven for 40 minutes, total thickness 0.326mm.

[0058] Performance comparison table 1. Temperature Resistance Comparison: Comparative Example 1 uses methyl vinyl silicone oil, and its long-term temperature resistance range is only -50~200°C. Compared with the -70~320°C of Example 1, the low-temperature toughness and high-temperature stability are significantly reduced, verifying the effect of the phenyl structure on improving the temperature resistance.

[0059] 2. Comparison of voltage resistance: The breakdown voltages of Examples 1-3 all exceed 6.5 kV / mm, while that of Comparative Example 1 is only 1.2 kV / mm, indicating that the addition of PI and phenyl vinyl silicone oil system effectively improves the insulation strength of the material through molecular structure optimization.

[0060] 3. Comparison of thermal conductivity: The thermal conductivity of Examples 1-3 is 6.7%-22.2% higher than that of Comparative 1, which is attributed to the better interfacial compatibility between phenyl vinyl silicone oil and thermally conductive filler, which reduces phonon scattering and optimizes the continuity of the thermal conductive network.

[0061] 4. Volume resistivity comparison: The insulation performance of the embodiment is better than that of the comparative example, further demonstrating the advantage of the phenyl structure in maintaining high insulation and meeting the safety requirements under high-voltage conditions.

[0062] 5. Comparison of filling of alumina powder with different particle sizes: The appearance of the embodiment is smooth and flat, without defects such as pinholes and holes. The appearance of comparative example 2 is rough, with pinholes and holes. At the same time, the pinholes and holes also cause a decrease in thermal conductivity and pressure resistance.

[0063] The above embodiments are preferred implementation modes of the present invention, but the implementation modes of the present invention are not limited to the above embodiments. Any other changes, modifications, substitutions, combinations, and simplifications that do not deviate from the spirit and principles of the present invention should be considered as equivalent replacement methods and are included in the scope of protection of the present invention.

Claims

1. A thermally conductive silicone gasket for high-temperature and high-pressure automobiles, comprising a three-layer structure: a first thermally conductive PI layer, an intermediate thermally conductive silicone layer, and a third thermally conductive PI layer. The intermediate thermally conductive silicone layer is disposed between the first and third thermally conductive PI layers, and the intermediate thermally conductive silicone layer contains phenyl vinyl silicone oil.

2. The high-temperature and high-pressure resistant thermally conductive silicone gasket for automobiles according to claim 1, wherein the intermediate thermally conductive silicone layer is prepared from phenyl vinyl silicone oil, hydrogen-containing silicone oil, platinum catalyst, hydrosilylation reaction inhibitor, and thermally conductive powder.

3. The thermally conductive silicone gasket for high temperature and high pressure automobiles according to claim 2, wherein the thermally conductive powder comprises aluminum oxide with different particle size ratios, and optionally contains zinc oxide, aluminum nitride or boron nitride.

4. The high-temperature and high-pressure resistant thermally conductive silicone gasket for automobiles according to claim 2, wherein the thermally conductive powder comprises alumina with different particle size ratios, wherein, by weight, alumina with a particle size of approximately 15 μm accounts for 60%-70%; alumina with a particle size of approximately 2 μm accounts for 20%-30%; and submicron alumina with a particle size of approximately 100 nm accounts for 10%-15%.

5. The thermally conductive silicone gasket for high temperature and high pressure automobiles according to claim 2, wherein the thermally conductive powder comprises alumina with different particle size ratios, and the alumina powder is pretreated with a silane coupling agent; and / or, the amount of silane coupling agent added is 1.0%-1.5% of the total mass of alumina; And / or, the hydrosilylation reaction inhibitor is 1-ethynylcyclohexanol. And / or, the hydrogen-containing silicone oil includes terminal hydrogen-containing silicone oil and end-side hydrogen-containing silicone oil.

6. The high-temperature and high-pressure resistant thermally conductive silicone gasket for automobiles according to claim 2, wherein, calculated by weight, for every 100 parts by weight of the thermally conductive powder, 5.0-6.5 parts of phenyl vinyl silicone oil, 0.40-0.50 parts of end hydrogen silicone oil, and 0.25-0.35 parts of end-side hydrogen silicone oil are added; and a catalytic amount of a platinum catalyst and a hydrosilylation reaction inhibitor are added.

7. The thermally conductive silicone gasket for high temperature and high pressure automobiles according to claim 2, wherein the thermal conductivity of the first thermally conductive PI layer and the third thermally conductive PI layer is 0.36 W / m·K or 0.6 W / m·K; And / or, the thickness of the first thermally conductive PI layer and the third thermally conductive PI layer is 0.038 mm or 0.050 mm; And / or, the thickness of the intermediate thermally conductive silicone layer is 0.25-0.40 mm; And / or, the total thickness of the thermally conductive silicone gasket can be controlled between 0.3 mm and 0.5 mm.

8. A method for preparing the high-temperature and high-pressure resistant thermally conductive silicone gasket for automobiles according to claim 1, comprising the following steps: Calendering molding: Place the mixed thermal conductive silicone between the upper and lower layers of thermal conductive PI, and use a calender to press it into a sheet structure with a thickness of 0.25-0.40mm. Baking and curing: The sheet structure after calendering is sent to the drying tunnel for baking and curing, and finally an ultra-thin thermal conductive silicone gasket that is resistant to high temperature and high pressure is produced.

9. The method according to claim 8, wherein the thermally conductive silica gel is prepared by the following method: Powder pretreatment: Take thermal conductive powder, add silane coupling agent, put it into a blender and stir it to complete the pretreatment of the powder to prevent powder agglomeration; Dry mixing: put the pre-treated thermal conductive powder into the mixer and stir until the powder is evenly mixed; Wet mixing: Add phenyl vinyl silicone oil, hydrogen silicone oil, platinum catalyst, and hydrosilylation reaction inhibitor to the dry-mixed powder, and mix in a blender at a mixing speed of 30-100 rpm until the materials are evenly mixed.

10. The method according to claim 8, wherein the baking time is 20 min-60 min, and the baking tunnel temperature is 100-150°C.

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