Low-permeability oil silicone thermal conductive gasket and its preparation method

Abstract

The present invention relates to a low-permeability oil silicone thermal conductive gasket and a preparation method thereof. The low-permeability oil silicone thermal conductive gasket of the present invention is composed of an intermediate thermal conductive layer, a first coating located on one side of the intermediate thermal conductive layer, and a second coating located on the other layer of the intermediate thermal conductive layer. At least one of the first coating and the second coating is composed of an organopolysiloxane resin with a molar ratio of silicon hydride (Si-H functional group) to vinyl of 0.8 to 1.5. The organopolysiloxane resin is formed by catalytic polymerization cross-linking reaction of hydrogen-containing silicone oil, vinyl silicone oil, inhibitor and catalyst. The thicknesses of the first coating and the second coating are each 0.001 mm to 0.500 mm.

Description

Technical Field

[0001] The present invention relates to the field of thermal interface materials, and particularly to a low-permeability oil organic silicone thermal conductive gasket and a preparation method thereof. Background Art

[0002] The additive silicone rubber thermal conductive gasket is a sheet-like thermal conductive material, which is vulcanized by adding silicone rubber and thermal conductive fillers. It has the advantages of adjustable thermal conductivity, convenient installation, reusable, etc., and has been widely used in the fields of electronics, electrical appliances, communications, transportation, aviation, etc. In recent years, with the upgrading of electronic products, the market has put forward higher requirements for the performance of thermal conductive silicone gaskets. In addition to high thermal conductivity, low thermal resistance, appropriate compression resilience and low compression stress, the low-permeability oil performance has also received extensive attention.

[0003] Chinese Patent Application Publication CN109401732A provides a low-permeability oil thermal conductive silicone gasket, which adjusts the silicon-hydrogen ratio to control the crosslinking degree of the rubber compound, so that the rubber compound reacts fully, reduces the reactants remaining due to incomplete reaction, and thus the obtained thermal conductive silicone gasket has a low weight loss rate and no oil leakage phenomenon.

[0004] Chinese Patent Application Publication CN105566920A provides a low-permeability oil ultra-soft thermal conductive silicone composition and a thermal conductive silicone gasket, which realize the staged occurrence of vulcanization and crosslinking of silicone rubber through the ratio of two liquid silicones with specific composition and viscosity and thermal conductive fillers.

[0005] Chinese Patent Application Publication CN104403330A discloses a low-permeability oil type thermal conductive silicone gasket, which obtains a low-permeability oil type thermal conductive silicone gasket through specific components and contents and a specific preparation process.

[0006] However, the present invention lacks a low-permeability oil organic silicone thermal conductive gasket applicable to various thermal conductive material layers with a wider range of material compositions and contents, and a method for forming a thermal conductive gasket composed of various thermal conductive material layers into a low-permeability oil organic silicone thermal conductive gasket. Summary of the Invention

[0007] In view of the above problems, the present invention provides a low-permeability oil organic silicone thermal conductive gasket, characterized in that the gasket comprises an intermediate thermal conductive layer, a first coating on one side of the intermediate thermal conductive layer, and a second coating on the other side of the intermediate thermal conductive layer; or the gasket is composed of an intermediate thermal conductive layer, a first coating on one side of the intermediate thermal conductive layer, and a second coating on the other side of the intermediate thermal conductive layer.

[0008] In the low-permeability oil silicone thermal conductive gasket of the present invention, at least one of the first coating and the second coating contains or consists of an organopolysiloxane resin with a molar ratio of Si-H functional groups to vinyl groups of 0.8 to 1.5, and the thickness of the first coating is 0.001 mm to 0.500 mm, and the thickness of the second coating is 0.001 mm to 0.500 mm. Preferably, the thickness of the first coating and the thickness of the second coating are each preferably 0.005 mm to 0.200 mm, more preferably 0.010 mm to 0.100 mm.

[0009] In the low-permeability oil silicone thermal conductive gasket of the present invention, the molar ratio of Si-H functional groups to vinyl groups in the organopolysiloxane resin in the first coating and / or the second coating is 1.0 to 1.2.

[0010] In the low-permeability oil silicone thermal conductive gasket of the present invention, the organopolysiloxane resin is formed by catalytic polymerization cross-linking reaction of hydrogen-containing silicone oil, vinyl silicone oil, inhibitor and catalyst.

[0011] In the low-permeability oil silicone thermal conductive gasket of the present invention, the catalytic polymerization cross-linking reaction of the organopolysiloxane for forming the first coating and the second coating is carried out as follows: reacting 2 parts by weight to 45 parts by weight of hydrogen-containing silicone oil, 60 parts by weight to 98 parts by weight of vinyl silicone oil, 0.01 part by weight to 1.0 part by weight of inhibitor and 0.05 part by weight to 1.0 part by weight of catalyst at a temperature of 15°C to 150°C for 20 min to 180 min.

[0012] In the low-permeability oil silicone thermal conductive gasket of the present invention, the vinyl silicone oil is one or more of terminal vinyl silicone oil, side-chain vinyl silicone oil, and mono-vinyl silicone oil, preferably one or more of terminal vinyl silicone oil and side-chain vinyl silicone oil, and the side groups on the silicon atoms in the silicone oil main chain are phenyl or methyl; the hydrogen-containing silicone oil is one or more of terminal hydrogen-containing silicone oil, side hydrogen-containing silicone oil, and terminal hydrogen side hydrogen-containing silicone oil, preferably one or more of side hydrogen-containing silicone oil and terminal hydrogen side hydrogen-containing silicone oil, and the side groups on the silicon atoms in the silicone oil main chain are phenyl or methyl. Preferably, the case where the vinyl silicone oil is terminal vinyl silicone oil and the case where the hydrogen-containing silicone oil is terminal hydrogen-containing silicone oil do not exist simultaneously.

[0013] The inhibitor is one or a combination of 1-ethynyl-1-cyclohexanol, tetramethyltetravinylcyclotetrasiloxane, 2-methyl-3-butyn-2-ol, 3-methyl-1-ethynyl-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-dodecyn-3-ol, dibutyl maleate, and diisooctyl maleate; the catalyst is one or a combination of chloroplatinic acid, chloroplatinic acid-isopropanol complex, and platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex.

[0014] In the low-permeability oil silicone thermal conductive gasket of the present invention, the intermediate thermal conductive layer is composed of the following components by weight: 100 parts by weight of vinyl silicone oil, 1 to 50 parts by weight of hydrogen-containing silicone oil, 0.01 to 1.0 part by weight of inhibitor, 0.1 to 1.0 part by weight of catalyst, 400 to 2500 parts by weight of thermal conductive filler, and 1 to 20 parts by weight of nano cerium oxide.

[0015] In the low-permeability oil silicone thermal conductive gasket of the present invention, the thickness of the intermediate thermal conductive layer is 0.1 mm to 10 mm, such as 0.5 mm, 1.0 mm, 2.0 mm, 3.0 mm, 4.0 mm, 5.0 mm, 7.0 mm, 8.0 mm, 9.0 mm.

[0016] Another aspect of the present invention provides a method for preparing a low-permeability oil silicone thermal conductive gasket, characterized in that the preparation method includes the following steps:

[0017] (1) High-temperature vacuum treatment of vinyl silicone oil and hydrogen-containing silicone oil;

[0018] (2) Preparing a semi-finished thermal conductive gasket with only an intermediate layer;

[0019] (3) Preparing an organopolysiloxane resin solution; and

[0020] (4) Coating the organopolysiloxane resin solution on both sides of the semi-finished thermal conductive gasket as the intermediate layer, so as to form a first coating on one side of the semi-finished thermal conductive gasket and a second coating on the other side of the semi-finished thermal conductive gasket, thereby obtaining the low-permeability oil silicone thermal conductive gasket.

[0021] In the method for preparing a low-permeability oil silicone thermal conductive gasket of the present invention, the high temperature in step (1) is 160°C to 220°C, the vacuum degree is -0.095 MPa to -0.1 MPa, and the treatment time is 5 h to 10 h.

[0022] The present invention is reasonably designed and has a simple process. On the basis of the formulation design, by changing the product structure and adding an organopolysiloxane resin with adsorption crosslinking and barrier penetration functions to the surface of the heat-conducting gasket material, the oil leakage phenomenon of the product can be reduced without affecting the original thermal conductivity and other basic properties. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] The non-limiting embodiments of the present invention will now be described by way of example only and with reference to the following drawings:

[0024] Figure 1 is a schematic cross-sectional view of the low-permeation oil-silicone heat-conducting gasket of the present invention.

[0025] Figure 2 is a photograph showing an existing technology silicone heat-conducting gasket without a coating and the silicone heat-conducting gasket with a coating of the present invention after being tested under experimental conditions. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0026] The present invention will now be described more fully hereinafter with reference to the accompanying drawings, in which some but not all embodiments of the present invention are shown.

[0027] The present invention as described should not be limited to the specific embodiments disclosed, and modifications and other embodiments are also included within the scope of the present invention. Although specific terms are employed herein, they are used in a general and descriptive sense only and not for purposes of limitation.

[0028] Throughout this specification and the following claims, the singular forms "a", "an" and "the" include plural forms unless the context clearly dictates otherwise.

[0029] The terms and phrases used herein are for the purpose of description and should not be regarded as limiting. The use of the terms "comprising", "including", "having" and "containing" and their variants is intended to cover the items listed hereinafter and their equivalents as well as other items.

[0030] In the prior art, heat-conducting / dissipating silicone gaskets all achieve low oil leakage through specific compositions and ratios, which will hinder the use of materials that can achieve better thermal conductivity or other better physical properties but have greater oil leakage, or will hinder the use of materials that are cheaper or more easily available but have greater oil leakage.

[0031] To solve this problem, the inventors of the present invention studied the oil leakage situation of the heat-conducting silicone gasket. The main components of the oil leaking from the gasket are small molecule silicone oil impurities in vinyl silicone oil or hydrogen-containing silicone oil, and unreacted vinyl silicone oil. Based on this understanding, the inventors of the present invention put forward the following basic concept:

[0032] (1) High-temperature vacuum treatment of vinyl silicone oil and hydrogen-containing silicone oil can reduce the content of small molecules in the raw materials. At the same time, a terminal hydrogen silicone oil chain extender is introduced to increase the molecular weight of unreacted vinyl silicone oil after vulcanization and reduce oil leakage. Oil leakage can be reduced without increasing the viscosity of the silicone oil / thermal conductive filler system and the final gasket hardness.

[0033] (2) Nano-ceria treated with a coupling agent is added to the thermal conductive filler. By using the principle of physical cross-linking between cerium oxide and the molecular chain of polysiloxane, the probability of oil leakage is reduced.

[0034] (3) On the upper and lower surfaces of the gasket, an organopolysiloxane resin coating with a ratio of silicon hydride to vinyl of 0.8 to 1.5 is added to adsorb and cross-link part of the unreacted vinyl silicone oil, and reduce oil leakage through the blocking effect of the dense surface layer. By adjusting the coating thickness and formulation, the effects of heat conduction, low hardness, and low deformation stress can be achieved.

[0035] The high-temperature vacuum treatment of vinyl silicone oil and hydrogen-containing silicone oil in the present invention is, for example, at 160 °C to 220 °C, a vacuum degree of -0.095 MPa to -0.1 MPa, and a treatment time of 5 h to 10 h.

[0036] In the vinyl silicone oil treated by high-temperature vacuum in the present invention, the content of small molecular weight raw materials that can volatilize and escape when heated at 150 °C for 3 h is reduced from 1.0% to 1.3% to 0.05% to 0.30%.

[0037] In the hydrogen-containing silicone oil treated by high-temperature vacuum in the present invention, the content of small molecular weight raw materials that can volatilize and escape when heated at 150 °C for 3 h is reduced from 1.0% to 1.8% to 0.1% to 0.40%.

[0038] Relative to 100 parts by weight of vinyl silicone oil, the dosage of the terminal hydrogen silicone oil chain extender in the present invention is 2 parts by weight to 30 parts by weight.

[0039] Relative to 100 parts by weight of hydrogen-containing silicone oil, the dosage of the terminal hydrogen silicone oil chain extender in the present invention is 17 parts by weight to 87 parts by weight.

[0040] Due to the addition of the terminal hydrogen silicone oil chain extender, the average molecular weight of unreacted vinyl silicone oil that can seep out after vulcanization can be increased to 1.5 to 3.2 times.

[0041] The terminal hydrogen silicone oil refers to a hydrogen-containing silicone oil with Si-H structures at both ends of the molecular chain.

[0042] The terminal hydrogen silicone oil chain extender can be, for example, commercially available terminal hydrogen silicone oils with specifications such as 30 cps, 100 cps, and 500 cps.

[0043] The nano-ceria of the present invention is nano-ceria treated with a coupling agent, and the coupling agent is, for example, one or more of γ-(2,3-epoxypropoxy)propyltrimethoxysilane and dodecyltrimethoxysilane, and the dosage is, for example, 0.3% to 5.0% of the total weight of the resin.

[0044] The upper surface and the lower surface of the heat-conducting silicone gasket of the present invention can be respectively coated with a first coating of an organopolysiloxane resin with a ratio of silicon hydride to vinyl of 0.8 to 1.5 and a second coating of an organopolysiloxane resin to adsorb and crosslink unreacted vinyl silicone oil and form a dense barrier layer.

[0045] The thickness of the coating is, for example, 0.001 mm to 0.500 mm, preferably 0.005 mm to 0.200 mm, and more preferably 0.010 mm to 0.100 mm. The thicknesses of the first coating of the organopolysiloxane resin and the second coating of the organopolysiloxane resin are both within the above range and can be the same or different.

[0046] The first coating of the organopolysiloxane resin and the second coating of the organopolysiloxane resin may contain 2 to 45 parts by weight of hydrogen-containing silicone oil, 60 to 98 parts by weight of vinyl silicone oil, 0.01 to 1.0 part by weight of inhibitor, and 0.05 to 1.0 part by weight of catalyst.

[0047] The first coating of the organopolysiloxane resin and the second coating of the organopolysiloxane resin can be formed by the following method: reacting 2 to 45 parts by weight of hydrogen-containing silicone oil, 60 to 98 parts by weight of vinyl silicone oil, 0.01 to 1.0 part by weight of inhibitor, and 0.05 to 1.0 part by weight of catalyst at a temperature of 15 to 150 °C for 20 to 180 min.

[0048] The vinyl silicone oil is, for example, one or more of end-vinyl silicone oil with 500 cps, end-vinyl silicone oil with 1000 cps, and side-chain vinyl silicone oil with 500 cps and 0.35 mmol / g.

[0049] The hydrogen-containing silicone oil is, for example, one or more of hydrogen-containing silicone oil with a hydrogen content of 0.3 mmol / g, hydrogen-containing silicone oil with a hydrogen content of 1.0 mmol / g, hydrogen-containing silicone oil with a hydrogen content of 6.0 mmol / g, and end-hydrogen silicone oil with a hydrogen content of 0.16 mmol / g.

[0050] The inhibitor is, for example, one or more of 1-ethynyl-1-cyclohexanol, tetramethyltetravinylcyclotetrasiloxane, and diisooctyl maleate.

[0051] The catalyst is, for example, one or more of chloroplatinic acid-isopropanol complex and platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex.

[0052] In the low-permeability oil silicone thermal conductive gasket of the present invention, the intermediate thermal conductive layer is composed of the following weight components: 100 parts of vinyl silicone oil, 1 to 50 parts of hydrogen-containing silicone oil, 0.01 to 1.0 part of inhibitor, 0.1 to 1.0 part of catalyst, 400 to 2500 parts of thermal conductive filler, and 0 to 20 parts of nano-ceria.

[0053] The vinyl silicone oil is, for example, terminal vinyl polydimethylsiloxane with 500 cps, terminal vinyl polydimethylsiloxane with 1000 cps, and side-chain vinyl polydimethylsiloxane with 0.35 mmol / g and 500 cps.

[0054] The hydrogen-containing silicone oil is, for example, one or more of hydrogen-containing silicone oil with a hydrogen content of 0.3 mmol / g, hydrogen-containing silicone oil with a hydrogen content of 1.0 mmol / g, hydrogen-containing silicone oil with a hydrogen content of 6.0 mmol / g, and terminal hydrogen silicone oil with a hydrogen content of 0.16 mmol / g.

[0055] The inhibitor is, for example, one or more of 1-ethynyl-1-cyclohexanol, tetramethyltetravinylcyclotetrasiloxane, and diisooctyl maleate.

[0056] The thermal conductive filler is, for example, one or more of spherical alumina, boron nitride, aluminum nitride, and zinc oxide.

[0057] The catalyst is, for example, one or more of chloroplatinic acid-isopropanol complex and platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex.

[0058] The nano-ceria is, for example, nano-ceria with an average particle size of 30 nm and nano-ceria with an average particle size of 200 nm.

[0059] The low-permeability oil silicone thermal conductive gasket of the present invention has excellent effects of heat conduction, low hardness, and low deformation stress.

[0060] The thermal conductivity of the low-permeability oil silicone thermal conductive gasket of the present invention can be 0.7 W / m·K to 14 W / m·K, preferably 1.2 W / m·K to 6.0 W / m·K.

[0061] The hardness of the low-permeability oil silicone thermal conductive gasket of the present invention can be Shore 00 10 to Shore 00 80, preferably Shore 00 15 to Shore 00 40.

[0062] The deformation stress of the low-permeability oil silicone thermal conductive gasket of the present invention can be 5 N to 310 N, preferably 10 N to 180 N.

[0063] Another aspect of the present invention provides a production method of a low-permeability oil-silicone thermal conductive gasket, which mainly includes the following steps: (1) high-temperature vacuum treatment of vinyl silicone oil and hydrogen-containing silicone oil; (2) production of a semi-finished thermal conductive gasket with only an intermediate layer; (3) preparation of an organopolysiloxane resin solution for the first coating and the second coating; (4) coating the organopolysiloxane resin solution on both sides of the semi-finished product to obtain the low-permeability organosilicon thermal conductive gasket of the present invention.

[0064] In the production method of the low-permeability oil-silicone thermal conductive gasket of the present invention, the high temperature in step (1) is 160°C to 220°C, the vacuum degree is -0.095 to -0.1 MPa, and the treatment time is 5 h to 10 h.

[0065] In the present invention, the coating of the organopolysiloxane resin solution on the intermediate layer can be implemented by the following methods: spraying method, roll coating method, brushing method. Among them, the roll coating method is preferred. The specific process is to add the organopolysiloxane resin solution to be coated between the oppositely rotating steel roll and rubber roll, and control the amount of glue coated through the roll gap. The cured intermediate film passes under the steel roll at a constant speed, and the glue liquid is coated on the film during the rotation of the steel roll.

[0066] In step (4), the coated organopolysiloxane resin solution can be cured at room temperature or by heating. The curing temperature is between 15°C and 150°C, and the curing time is between 20 and 180 min. The present invention preferably cures by heating. It is dried at a temperature of 100°C to 135°C for 20 to 40 min to form a coating with a thickness of 0.001 mm to 0.50 mm.

[0067] Examples

[0068] The following examples are used to exemplarily show the implementation manners and effects of the present invention.

[0069] Example 1

[0070] (1) High-temperature vacuum treatment of vinyl silicone oil and hydrogen-containing silicone oil; The terminal vinyl polydimethylsiloxane with viscosities of 500 cps and 100 cps was treated at a temperature of 190 to 210°C under a vacuum of -0.097 to -0.10 MPa for 8 h. After cooling, the content of small molecular weight raw materials that could volatilize when heated at 150°C for 3 h was tested, and its volatility decreased from the initial 1.0% to 1.3% to 0.05% to 0.20% (by weight). The hydrogen-containing silicone oil with a hydrogen content of 0.3 mmol / g and the hydrogen-containing silicone oil with a hydrogen content of 6.0 mmol / g were treated at a temperature of 160 to 175°C under a vacuum of -0.097 to -0.10 MPa for 5 h. After cooling, the content of small molecular weight raw materials that could volatilize when heated at 150°C for 3 h was tested, and its volatility decreased from the initial 1.0% to 1.8% to 0.25% to 0.40% (by weight).

[0071] (2) Produce semi-finished heat-conducting gaskets with only an intermediate layer;

[0072]

[0073]

[0074] Add the vinyl-terminated polydimethylsiloxane with a viscosity of 500 cps, vinyl-terminated polydimethylsiloxane with a viscosity of 1000 cps, hydrogen-containing silicone oil H1, hydrogen-containing silicone oil H2, hydrogen-terminated silicone oil H3, and inhibitor described in the above table into a planetary mixer in sequence and mix for 10 to 30 minutes. Then add a platinum catalyst into the mixer, evacuate to -0.095 Mpa and stir for 5 to 15 minutes to obtain a uniformly stirred resin mixture system.

[0075] Add spherical alumina A2, spherical alumina A1, and nano-cerium oxide into the uniformly stirred resin in three batches in sequence. After each addition, evacuate and stir for 15 to 30 minutes. After mixing evenly, add the next batch of powder materials. After stirring is completed, a colloidal mixture before molding is obtained.

[0076] Roll the uniformly mixed colloid on a molding device into a sample sheet with a thickness of 2.54 mm, and heat it in a tunnel furnace at 120 to 135 °C for 25 to 45 minutes to obtain a semi-finished heat-conducting sheet of the intermediate layer.

[0077] (3) Preparation of an organopolysiloxane resin solution for the first coating and the second coating;

[0078]

[0079]

[0080] Add the vinyl-terminated polydimethylsiloxane with a viscosity of 500 cps, vinyl-terminated polydimethylsiloxane with a viscosity of 1000 cps, hydrogen-containing silicone oil H1, hydrogen-containing silicone oil H2, and inhibitor described in the above table into a planetary mixer in sequence and mix for 10 to 30 minutes. Then add a platinum catalyst into the mixer, evacuate to -0.095 Mpa and stir for 5 to 15 minutes to obtain an organopolysiloxane resin solution that can be used for the first coating and the second coating.

[0081] (4) Coat the organopolysiloxane resin solution on both sides of the semi-finished product to obtain the low-permeability silicone heat-conducting gasket of the present invention.

[0082] Using a roll coating equipment, control the gap between the roll and the intermediate layer heat conductive gasket to be 0.03 - 0.05 mm, and evenly coat the above-prepared organopolysiloxane resin solution with a thickness of 0.05 mm on the upper surface of the intermediate layer. Cure it by heating in a tunnel furnace at 120 to 135 °C for 25 to 45 min to obtain the adhesive layer 1 (i.e., the first coating). After turning the gasket over, repeat the above process to obtain the adhesive layer 2 (i.e., the second coating). Different sizes of low-oil-leakage silicone heat conductive gaskets can be obtained by cutting.

[0083] Comparative Example 1

[0084] Only produce the intermediate heat conductive gasket according to the step (2) of Example 1 as the silicone heat conductive gasket.

[0085] Test

[0086] The thickness, hardness, thermal conductivity, thermal resistance, maximum stress (N) at 30% deformation, balance force (N) at 30% deformation, and deformation (%) under 10 psi pressure of the silicone heat conductive gaskets prepared in Example 1 and Comparative Example 1 of the present invention were measured.

[0087] Among them, the measurement method of the thermal conductivity is: measured by using the TPS2500 tester of Hot Disk AB Company.

[0088] Among them, the measurement method of the maximum stress (N) at 30% deformation is: use the C43 microcomputer-controlled electronic universal testing machine of Material Testing Systems Company for testing. Use a 1-square-inch test platform. Precision fit and place a 2.54-mm-thick sample piece of 24 * 24 mm in a 24 * 24 mm fixture and then place it on the test platform. Press it down at a speed of 25.4 mm / min until the sample piece deforms by 30%. Stop pressing and stabilize for 5 min. The maximum peak value in the pressure curve is the maximum stress at 30% deformation.

[0089] Among them, the measurement method of the balance force (N) at 30% deformation is: the test method is the same as above. The stress measured after balancing for 5 min in the curve is its balance force.

[0090] Among them, the measurement method of the deformation (%) under 10 psi pressure is: use the C43 microcomputer-controlled electronic universal testing machine of Material Testing Systems Company for testing. Use a 1-square-inch test platform. Precision fit and place a 2.54-mm-thick sample piece of 1 square inch on the test platform. Press it down at a speed of 0.254 mm / min and test its deformation under 5 to 100 psi pressure. Read the deformation value at 10% psi.

[0091] The above test results are shown in Table 1.

[0092] Furthermore, after heating the silicone thermal conductive gaskets prepared in Example 1 and Comparative Example 1 at 125 °C for 144 h under a load of 1 kg, their oil leakage rates were measured. The test results are shown in Table 1, and the photos of the silicone thermal conductive gaskets before and after heat treatment and the photos of the oil leakage situation are shown in Figure 2 .

[0093] Table 1

[0094]

[0095] According to the results shown in Table 1 above, it can be determined that, compared with the comparative example, the silicone thermal conductive gasket of the present invention can effectively inhibit the oil leakage rate during long-term heating, reduce the oil leakage rate by 80% (calculated based on typical values), and improve the hardness and deformation resistance of the silicone thermal conductive gasket.

Claims

1. A low-permeability oil silicone thermal conductive gasket, characterized in that, The gasket includes an intermediate heat-conducting layer, a first coating on one side of the intermediate heat-conducting layer, and a second coating on the other side of the intermediate heat-conducting layer; or the gasket is composed of an intermediate heat-conducting layer, a first coating on one side of the intermediate heat-conducting layer, and a second coating on the other side of the intermediate heat-conducting layer, wherein the intermediate heat-conducting layer is composed of the following components by weight: 100 parts by weight of vinyl silicone oil, 1 part by weight to 50 parts by weight of hydrogen-containing silicone oil, 0.01 part by weight to 1.0 part by weight of inhibitor, 0.1 part by weight to 1.0 part by weight of catalyst, 400 parts by weight to 2500 parts by weight of heat-conducting filler, and 1 part by weight to 20 parts by weight of nano cerium oxide, wherein the thickness of the intermediate heat-conducting layer is 0.1 mm to 10 mm, and wherein each of the first coating and the second coating contains an organopolysiloxane resin with a molar ratio of Si-H functional group to vinyl of 0.8 to 1.5 or each is composed of an organopolysiloxane resin with a molar ratio of Si-H functional group to vinyl of 0.8 to 1.

5.

2. The low-permeability oil silicone thermal conductive gasket according to claim 1, wherein, The thickness of the first coating is 0.001 mm to 0.500 mm, and the thickness of the second coating is 0.001 mm to 0.500 mm.

3. The low-permeability oil silicone thermal conductive gasket according to claim 2, wherein, The molar ratio of Si-H functional group to vinyl in the organopolysiloxane resin is 1.0 to 1.

2.

4. The low-permeability oil silicone thermal conductive gasket according to claim 2, wherein, The organopolysiloxane resin is formed by the catalytic polymerization cross-linking reaction of hydrogen-containing silicone oil, vinyl silicone oil, inhibitor and catalyst.

5. The low-permeability oil silicone thermal conductive gasket according to claim 4, wherein, The catalytic polymerization cross-linking reaction of the organopolysiloxane used to form the first coating and the second coating is carried out as follows: reacting 2 parts by weight to 45 parts by weight of hydrogen-containing silicone oil, 60 parts by weight to 98 parts by weight of vinyl silicone oil, 0.01 part by weight to 1.0 part by weight of inhibitor and 0.05 part by weight to 1.0 part by weight of catalyst at a temperature of 15 °C to 150 °C for 20 min to 180 min.

6. The low-permeability oil silicone heat-conducting gasket according to claim 4, wherein, the vinyl silicone oil is one or more of terminal vinyl silicone oil, side-chain vinyl silicone oil, and mono-vinyl silicone oil, and the side groups on the silicon atoms in the silicone oil main chain are phenyl or methyl; the hydrogen-containing silicone oil is one or more of terminal hydrogen-containing hydrogen silicone oil, side hydrogen-containing hydrogen silicone oil, and terminal hydrogen side hydrogen-containing hydrogen silicone oil, and the side groups on the silicon atoms in the silicone oil main chain are phenyl or methyl; the inhibitor is one or a combination of 1-ethynyl-1-cyclohexanol, tetramethyltetravinylcyclotetrasiloxane, 2-methyl-3-butyn-2-ol, 3-methyl-1-ethynyl-3-ol, 3,5-dimethyl-1-hexyn-3-ol, 3-methyl-1-dodecyn-3-ol, dibutyl maleate, and diisooctyl maleate; the catalyst is one or a combination of chloroplatinic acid, chloroplatinic acid-isopropanol complex, and platinum(0)-1,3-divinyl-1,1,3,3-tetramethyldisiloxane complex.

7. The low-permeability oil silicone heat-conducting gasket according to claim 4, wherein, relative to 100 parts by weight of the vinyl silicone oil, 2 parts by weight to 30 parts by weight of terminal hydrogen silicone oil chain extender is added; and / or Based on 100 parts by weight of the hydrogen-containing silicone oil, 17 to 87 parts by weight of the end-hydrogen silicone oil chain extender is added.

8. A preparation method of an organosilicon thermal conductive gasket for low-permeability oil, characterized in that, The preparation method comprises the following steps: (1) High-temperature vacuum treatment of vinyl silicone oil and hydrogen-containing silicone oil; (2) Preparing a semi-finished heat-conducting gasket having only an intermediate layer; (3) Preparing an organopolysiloxane resin solution; and (4) Coating the organopolysiloxane resin solution on both sides of the semi-finished heat-conducting gasket as the intermediate layer, thereby forming a first coating on one side of the semi-finished heat-conducting gasket and forming a second coating on the other side of the semi-finished heat-conducting gasket to obtain the low oil-leakage organosilicon heat-conducting gasket, wherein the intermediate heat-conducting layer is composed of components in the following weights: 100 parts by weight of vinyl silicone oil, 1 to 50 parts by weight of hydrogen-containing silicone oil, 0.01 to 1.0 part by weight of inhibitor, 0.1 to 1.0 part by weight of catalyst, 400 to 2500 parts by weight of heat-conducting filler, and 1 to 20 parts by weight of nano cerium oxide, wherein the thickness of the intermediate heat-conducting layer is 0.1 mm to 10 mm, and wherein each of the first coating and the second coating comprises an organopolysiloxane resin with a molar ratio of Si-H functional group to vinyl of 0.8 to 1.5 or each is composed of an organopolysiloxane resin with a molar ratio of Si-H functional group to vinyl of 0.8 to 1.

5.

9. The preparation method of the low-permeability oil silicone thermal conductive gasket according to claim 8, wherein, The high temperature in step (1) is 160 °C to 220 °C, the vacuum degree is -0.095 MPa to -0.1 MPa, and the treatment time is 5 h to 10 h.

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