Insulating high-thermal-conductivity silicone rubber composition for motor and preparation method of insulating high-thermal-conductivity silicone rubber composition

Abstract

The invention relates to the field of functional silicone rubber materials, in particular to an insulating high-thermal-conductivity silicone rubber composition for a motor and a preparation method of the insulating high-thermal-conductivity silicone rubber composition. The insulating high-thermal-conductivity type silicone rubber composition for the motor is A / B double-component addition type RTV silica gel, and the molar weight ratio of Si-H to Si-Vi is (1.0-1.2): 1; wherein the insulating and heat-conducting filler composition comprises 25-30wt% of insulating and heat-conducting filler composition, and the insulating and heat-conducting filler composition comprises magnetic rod-shaped insulating and heat-conducting fillers which are directionally arranged in a silicone rubber matrix; and the adding amount of the magnetic rod-shaped insulating heat-conducting filler is 1-5wt%. According to the invention, the insulating heat-conducting fillers in different forms are combined and compounded to form a multi-dimensional three-dimensional heat-conducting network with excellent heat conductivity, so that the heat-conducting property and the electrical insulation property of the silicone rubber material are ensured, the filling amount of the insulating heat-conducting fillers can be reduced to 25-30wt%, and the processing property and the mechanical strength of a rear-end product can be further improved.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of functional silicone rubber materials, in particular to an insulating high-thermal-conductivity silicone rubber material in the field of motor assembly, and more particularly to an insulating high-thermal-conductivity silicone rubber composition for a motor and a preparation method thereof. BACKGROUND

[0002] The main chain of silicone rubber is mainly Si-O-Si-, which endows it with good chemical stability, high and low temperature flexibility, dielectric properties, and anti-aging properties. The side chain is an organic substituent group (such as Me, Ph, Et, etc.), and by adjusting the organic substituent group of the side chain, the anti-aging properties, corrosion resistance, high temperature resistance, and mechanical properties of the chain silicon glue can be controlled. The excellent properties of silicone rubber are widely used in the fields of motors and electronic packaging.

[0003] Silicone rubber is divided into high temperature vulcanized silicone rubber (HTV) and room temperature vulcanized silicone rubber (RTV) according to the vulcanization type. Room temperature vulcanized silicone rubber (RTV) is further divided into single-component room temperature vulcanized silicone rubber and two-component type room temperature vulcanized silicone rubber. The two-component type room temperature vulcanized silicone rubber has good process controllability and low shrinkage, and is more suitable as a sealing material for motors, such as motor sealing rings / damping sheets and motor sealing rings / damping sheets.

[0004] The two-component type room temperature vulcanized silicone rubber, also known as two-component addition type RTV silicone, is made of vinyl silicone oil containing unsaturated bonds as base glue and hydrogen-containing silicone oil as curing crosslinking agent. Through platinum catalyst, a three-dimensional elastomer is formed by silicon hydrogen addition reaction at room temperature or under heating. By controlling the Si-H content in the hydrogen-containing silicone oil, the hardness, wear resistance and mechanical properties of the formed silicone rubber can be adjusted to meet the needs of different use environments. The advantages of two-component addition type RTV silicone are: 1. Good environmental protection and processing performance: the reaction process can be deeply vulcanized without generating by-products; 2. Small shrinkage, the sealing ring / damping sheet material prepared therefrom has excellent dimensional stability and dimensional accuracy; 3. Excellent insulation, arc resistance, ozone resistance and weather resistance, and long-term use without aging, making it an ideal material for motors and electronic packaging.

[0005] With the development of the motor industry towards high power, more heat will be generated during the use of the motor. If this part of heat is not released in time, it will cause the temperature inside the motor to be too high, which will affect the service life and operation reliability and safety of the motor components. Higher requirements are put forward for the high thermal conductivity of the sealing ring / damping sheet.

[0006] The thermal conductivity of the addition type RTV silicone seal ring / damping sheet material prepared by room temperature vulcanization or high temperature accelerated vulcanization of traditional two-component addition type RTV silicone is between 0.16-251.0 W / (m·K), and the thermal conductivity is poor, which cannot meet the use requirement of high-power motor. Usually, insulation and thermal conductive fillers (such as alumina, silicon nitride, aluminum nitride, boron nitride, etc.) are added to the two-component addition type RTV silicone to prepare insulation and thermal conductive silicone. The prior art such as Gu J, Meng X, Tang Y, Li Y, Zhuang Q, Kong J. Hexagonal boron nitride / polymethyl-vinylsiloxane rubber dielectric thermally conductive composites with ideal thermal stabilities [J]. Composites Part A: Applied Science and Manufacturing discloses that hexagonal boron nitride / polymethyl-vinylsiloxane rubber insulation and thermal conductive composite material is prepared by hot compression method, and the thermal conductivity of the insulation and thermal conductive silicone prepared when the volume fraction of the hexagonal boron nitride filler is 40% is 1.11 W / (m·K) and the volume resistivity is >10 12 Ω·m.

[0007] The filling amount of the insulation and thermal conductive filler in the existing insulation and thermal conductive silicone is high (volume fraction ≥40%), which will affect the flowability, processability and mechanical strength of the insulation and thermal conductive silicone. For example, in the production of seal ring / damping sheet, the deviation of flowability will cause difficult filling, the insulation and thermal conductive silicone cannot be fully filled in the molding cavity, the surface defects of the produced silicone seal ring / damping sheet are more and the yield is poor, and the overall cost is high. Therefore, the application provides an insulation and high thermal conductive silicone composition for motor and a preparation method thereof. SUMMARY

[0008] In order to solve the problem of product surface defects caused by the high filling amount of insulation and thermal conductive filler in the existing two-component addition type RTV silicone in the production of motor seal ring / damping sheet, the applicant provides an insulation and high thermal conductive silicone composition for motor and a preparation method thereof.

[0009] The application provides an insulation and high thermal conductive silicone composition for motor, which is realized by the following technical scheme:

[0010] The application discloses an insulating and high-thermal-conductivity type silicone rubber composition for a motor, which is an A / B two-component addition type RTV silicone rubber; the A / B two-component addition type RTV silicone rubber comprises 25-30 wt% of an insulating and thermal-conductivity type filler composition, wherein the insulating and thermal-conductivity type filler composition comprises magnetic rod-shaped insulating and thermal-conductivity type fillers arranged in the silicone rubber matrix; and the magnetic rod-shaped insulating and thermal-conductivity type fillers are added in an amount of 1-5 wt%.

[0011] The application discloses an insulating and high-thermal-conductivity type silicone rubber composition for a motor, which is an A / B two-component addition type RTV silicone rubber; the A / B two-component addition type RTV silicone rubber comprises 25-30 wt% of an insulating and thermal-conductivity type filler composition, wherein the insulating and thermal-conductivity type filler composition comprises magnetic rod-shaped insulating and thermal-conductivity type fillers arranged in the silicone rubber matrix; and the magnetic rod-shaped insulating and thermal-conductivity type fillers are added in an amount of 1-5 wt%.

[0012] Preferably, the insulating and thermal-conductivity type filler composition is composed of surface-coated graphene, spherical insulating and thermal-conductivity type fillers, rod-shaped insulating and thermal-conductivity type fillers and flaky insulating and thermal-conductivity type fillers.

[0013] Preferably, the rod-shaped insulating and thermal-conductivity type filler composition is composed of rod-shaped insulating and thermal-conductivity type fillers and magnetic rod-shaped insulating and thermal-conductivity type fillers.

[0014] Further preferably, the mass ratio of the rod-shaped insulating and thermal-conductivity type fillers to the magnetic rod-shaped insulating and thermal-conductivity type fillers is 1:(0.5-2).

[0015] Further preferably, the magnetic rod-shaped insulating and thermal-conductivity type fillers are insulating and thermal-conductivity type whiskers with surface-loaded magnetic Fe3O4; and the rod-shaped insulating and thermal-conductivity type fillers are insulating and thermal-conductivity type whiskers with an OD of 0.1-5 mu m and an L of 5-100 mu m.

[0016] Preferably, the surface-coated graphene accounts for 0.10-2.0 wt% of the total mass of the insulating and thermal-conductivity type filler composition.

[0017] Further preferably, the surface-coated graphene comprises a graphene body and an insulating and thermal-conductivity coating layer coated on the graphene body, wherein the insulating and thermal-conductivity coating layer is made of any one of alumina particles, aluminum nitride particles, boron nitride particles, titanium nitride particles and silicon nitride particles through in-situ polymerization or self-assembly.

[0018] Preferably, the spherical insulating and thermal-conductivity type fillers account for 75-90 wt% of the total mass of the insulating and thermal-conductivity type filler composition.

[0019] Preferably, the spherical insulating and thermal-conductivity type fillers are at least one of spherical or near-spherical nano-alumina, nano-aluminum nitride, nano-boron nitride, nano-titanium nitride and nano-silicon nitride.

[0020] Preferably, the sheet-shaped insulating and heat-conductive filler is at least one of aluminum nitride nanosheet and boron nitride nanosheet.

[0021] By optimizing the conformational morphology of the insulating and heat-conductive filler composition, a more efficient multi-dimensional three-dimensional heat-conductive network structure can be formed, which ensures that the motor silicone rubber sealing ring / damping sheet has good thermal conductivity and electrical insulation performance while reducing the amount of insulating and heat-conductive filler, thereby improving the processing performance and mechanical strength of the downstream product.

[0022] Preferably, the molar ratio of Si-H to Si-Vi in the A / B two-component addition type RTV silicone glue is (1.0-1.2):1, which ensures the toughness and elasticity of the prepared motor silicone rubber sealing ring / damping sheet while imparting better mechanical strength.

[0023] Preferably, the A component includes a vinyl-terminated polysiloxane with a viscosity of 50-500 cSt, a vinyl-terminated polysiloxane with a viscosity of 500-5000 cSt, a heat-conductive filler composition, and a platinum catalyst. The high and low viscosity vinyl-terminated polysiloxanes are compounded as the base glue, which is beneficial to control the viscosity of the insulating and high-heat-conductive silicone rubber composition formed after mixing of the A / B components, thereby optimizing the flowability and processing performance of the insulating and high-heat-conductive silicone rubber composition.

[0024] Preferably, the B component includes a vinyl-terminated polysiloxane with a viscosity of 100-1000 cSt, a hydrogen-containing silicone oil crosslinking agent with a viscosity of 2-100 cSt, an inhibitor, and a heat-conductive filler composition.

[0025] Preferably, the total mass of the heat-conductive filler composition in the A component and the heat-conductive filler composition in the B component accounts for 25-30 wt% of the total mass of the A / B two-component addition type RTV silicone glue.

[0026] Preferably, the inhibitor is ethynylcyclohexanol and / or 3-methyl-1-dodecyn-3-ol.

[0027] Preferably, the hydrogen-containing silicone oil crosslinking agent with a viscosity of 2-100 cSt is compounded from a high hydrogen-containing silicone oil with low viscosity and a low hydrogen-containing silicone oil with higher viscosity, which is beneficial to control the viscosity of the insulating and high-heat-conductive silicone rubber composition formed after mixing of the A / B components, thereby optimizing the flowability and processing performance of the insulating and high-heat-conductive silicone rubber composition, while also ensuring the mechanical strength and flexibility of the prepared silicone rubber sealing ring / damping sheet.

[0028] The application provides a preparation method of an insulating and high-heat-conductive silicone rubber composition for a motor, which is realized by the following technical scheme:

[0029] A kind of preparation method of insulating high thermal conductivity type silicone rubber composition for motor, comprising the following steps:

[0030] Preparation of component A: vinyl-terminated polysiloxane with viscosity of 50-500 cSt, vinyl-terminated polysiloxane with viscosity of 500-5000 cSt, platinum gold catalyst are placed in a vacuum kneader for kneading treatment for 5-15 min, then the heat-conducting filler composition modified by silane coupling agent is added, and the kneading treatment is continued for 0.5-2 h, and the low molecular and bubbles are removed by vacuum degassing treatment, and the A component is obtained by cooling and discharging.

[0031] Preparation of component B: vinyl-terminated polysiloxane with viscosity of 100-1000 cSt, hydrogen-containing silicone oil crosslinking agent with viscosity of 2-100 cSt, inhibitor are placed in a vacuum kneader for kneading treatment for 5-15 min, then the heat-conducting filler composition modified by silane coupling agent is added, and the kneading treatment is continued for 0.5-2 h, and the low molecular and bubbles are removed by vacuum degassing treatment, and the B component is obtained by cooling and discharging.

[0032] In use, the A component and the B component are configured according to the molar ratio of Si-H / Si-Vi being (1.0-1.2):1, the accurate A component and the B component are measured and uniformly mixed to obtain the insulating high thermal conductivity type silicone rubber composition for motor.

[0033] Preferably, when the insulating high thermal conductivity type silicone rubber composition is used for producing and processing sealing ring / shock pad, the insulating high thermal conductivity type silicone rubber composition is punched in a forming mold, the forming mold is placed in a magnetic field environment, the magnetic field strength is 0.5-5 T, the magnetic field direction is perpendicular to the horizontal plane, and the sealing ring / shock pad product of the insulating high thermal conductivity type silicone rubber for motor can be obtained by curing at room temperature for 8-12 h and demolding.

[0034] The magnetic rod-shaped insulating heat-conducting filler is arranged and adjusted by the magnetic field, the arrangement direction of the magnetic rod-shaped insulating heat-conducting filler is vertical, which is beneficial to constructing a more efficient multidimensional three-dimensional heat-conducting network structure, and can effectively improve the heat-conducting performance of the insulating high thermal conductivity type silicone rubber product for motor.

[0035] In summary, the present application has the following advantages:

[0036] 1、The insulating high thermal conductivity type silicone rubber composition product has good thermal conductivity coefficient and electrical insulation performance, and the problem of surface defects of the product caused by the high filling amount of the insulating heat-conducting filler in the existing two-component addition type RTV silicone rubber for producing motor sealing ring / shock pad is solved.

[0037] 2、The amount of the insulating and heat-conducting filler of the high-thermal-conductivity silicone rubber composition in the application is beneficial to the lightweight design of the silicone rubber sealing ring / shock-absorbing sheet and motor, and thus the market competitiveness of the product can be improved. DETAILED DESCRIPTION

[0038] In order to further understand the creativity and technical progress of the present application, the preferred embodiments of the present application are discussed in detail below in combination with examples and comparative examples.

[0039] The insulating and high-thermal-conductivity silicone rubber composition for motor is a two-component addition type RTV silicone rubber, which comprises 25-30 wt% of an insulating and heat-conducting filler composition. The insulating and heat-conducting filler composition comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The amount of the magnetic rod-shaped insulating and heat-conducting fillers is 1-5 wt%. The magnetic rod-shaped insulating and heat-conducting fillers are arranged vertically by magnetic field, which is beneficial to the construction of a more efficient multidimensional three-dimensional heat-conducting network structure, and can effectively improve the heat-conducting performance of the insulating and high-thermal-conductivity silicone rubber product for motor, and thus the filling amount of the insulating and heat-conducting filler composition can be reduced under the premise of the same heat-conducting performance. The processing performance of the end product can be improved. The obtained insulating and high-thermal-conductivity silicone rubber composition has better flowability and is easier to completely fill the mold. The surface of the prepared motor sealing ring / shock-absorbing sheet is smooth and crack-free, the overall yield is improved, and the overall production cost is reduced.

[0040] Considering the directional arrangement of the magnetic rod-shaped insulating and heat-conducting fillers by the magnetic field, i.e., the adjustment of the magnetic rod-shaped insulating and heat-conducting fillers from disordered arrangement to vertical directional arrangement under the action of the magnetic field, the viscosity of the silicone rubber composition should not be too high in this process. Too high viscosity will limit the movement of the magnetic rod-shaped insulating and heat-conducting fillers and prolong the action time of the magnetic field, which is not conducive to the improvement of the production efficiency of the insulating and high-thermal-conductivity silicone rubber product. Therefore, the viscosity of the vinyl silicone oil and hydrogen-containing silicone oil in the A / B component formula needs to be adjusted.

[0041] The A component comprises vinyl-terminated polysiloxane with a viscosity of 50-500 cSt, vinyl-terminated polysiloxane with a viscosity of 500-5000 cSt, heat-conducting filler composition, and platinum catalyst.

[0042] The mass ratio of the vinyl-terminated polysiloxane with a viscosity of 50-500 cSt to the vinyl-terminated polysiloxane with a viscosity of 500-5000 cSt in the A component is 100:(10-40).

[0043] The B component includes a vinyl-terminated polysiloxane with a viscosity of 100-1000 cSt, a hydrogen-containing silicone oil crosslinking agent with a viscosity of 2-100 cSt, an inhibitor, and a thermally conductive filler composition.

[0044] The total mass of the thermally conductive filler composition in the A component and the thermally conductive filler composition in the B component accounts for 25-30 wt% of the total mass of the A / B two-component addition type RTV silicone adhesive.

[0045] The inhibitor is any one of ethynylcyclohexanol or 3-methyl-1-dodecyn-3-ol.

[0046] The hydrogen-containing silicone oil crosslinking agent with a viscosity of 2-100 cSt in the B component is compounded from a high hydrogen-containing silicone oil with low viscosity and a low hydrogen-containing silicone oil with higher viscosity, which is conducive to controlling the viscosity of the insulating high-thermal-conductivity silicone rubber composition formed after mixing of the A / B components and is conducive to shortening the time for directional arrangement of the magnetic rod-shaped insulating thermally conductive filler.

[0047] The ratio of the molar amount of Si-Vi in the A component to the molar amount of Si-H in the B component is 1:(1.0-1.2).

[0048] The insulating thermally conductive filler composition is composed of surface-coated graphene, spherical insulating thermally conductive filler, rod-shaped insulating thermally conductive filler, and flaky insulating thermally conductive filler.

[0049] The surface-coated graphene accounts for 0.10-2.0 wt% of the total mass of the insulating thermally conductive filler composition.

[0050] The surface-coated graphene includes a graphene body and an insulating thermally conductive coating layer coated on the graphene body, and the insulating thermally conductive coating layer is made of any one of aluminum oxide particles, aluminum nitride particles, boron nitride particles, titanium nitride particles, and silicon nitride particles by in-situ polymerization or self-assembly.

[0051] The surface-coated graphene has good thermal conductivity performance advantages, and the insulating thermally conductive coating layer coated on the surface can effectively block the electrical conductivity, so that it becomes an insulating high-thermal-conductivity filler with more excellent thermal conductivity performance. By incorporating a small amount of surface-coated graphene, the thermal conductivity performance of the insulating high-thermal-conductivity silicone rubber product can be effectively improved, and good insulating performance is also achieved. That is, by incorporating a small amount of surface-coated graphene, the amount of spherical insulating thermally conductive filler can be reduced, which is conducive to reducing the overall use amount of the insulating thermally conductive filler composition.

[0052] The rod-shaped insulating thermally conductive filler composition is composed of rod-shaped insulating thermally conductive filler and magnetic rod-shaped insulating thermally conductive filler. The mass ratio of the rod-shaped insulating thermally conductive filler to the magnetic rod-shaped insulating thermally conductive filler is 1:(0.5-2). Preferably, the mass ratio of the rod-shaped insulating thermally conductive filler to the magnetic rod-shaped insulating thermally conductive filler is 1:1.

[0053] The magnetic rod-shaped insulating and heat-conductive filler is an insulating and heat-conductive whisker with a surface loaded with magnetic Fe3O4. The rod-shaped insulating and heat-conductive filler is an insulating and heat-conductive whisker with an OD of 0.1-5 μm and an L of 5-100 μm. Specifically, the magnetic rod-shaped insulating and heat-conductive filler is a boron nitride whisker with a surface loaded with magnetic Fe3O4. The rod-shaped insulating and heat-conductive filler is a boron nitride whisker (without a surface loaded with magnetic Fe3O4). The rod-shaped insulating and heat-conductive filler composition with a high aspect ratio serves as a "heat-conductive bridge" for the connected coating type graphene, the spherical insulating and heat-conductive filler, and the flaky insulating and heat-conductive filler, forms a multi-dimensional three-dimensional heat-conductive network structure with a higher heat flux, improves the heat conductivity of the heat-conductive and insulating silicone rubber composition product, and ensures that the product still has good electrical insulation performance.

[0054] The spherical insulating and heat-conductive filler accounts for 75-90 wt% of the total mass of the insulating and heat-conductive filler composition. The spherical insulating and heat-conductive filler is conventional and can be at least one of spherical or near-spherical nano-aluminum oxide, nano-aluminum nitride, nano-boron nitride, nano-titanium nitride, and nano-silicon nitride.

[0055] The flaky insulating and heat-conductive filler is at least one of an aluminum nitride nanosheet and a boron nitride nanosheet.

[0056] The inventor optimizes the formula design of the surface-coated graphene, the spherical insulating and heat-conductive filler, the rod-shaped insulating and heat-conductive filler, and the flaky insulating and heat-conductive filler, and arranges the magnetic rod-shaped insulating and heat-conductive filler in a specific direction, so that a more efficient multi-dimensional three-dimensional heat-conductive network structure can be formed with only 25-30 wt% of the insulating and heat-conductive filler composition, ensuring that the silicone rubber product for electric machines has good heat conductivity and electrical insulation performance.

[0057] A method for preparing an insulating and highly heat-conductive silicone rubber composition for electric machines includes the following steps:

[0058] Preparation of component A: Put the vinyl-terminated polysiloxane with a viscosity of 50-500 cSt, the vinyl-terminated polysiloxane with a viscosity of 500-5000 cSt, and the platinum gold catalyst into a vacuum kneader for kneading treatment for 5-15 min, then add the heat-conductive filler composition modified by a silane coupling agent, continue kneading treatment for 0.5-2 h, remove low molecules and bubbles through vacuum degassing treatment, and cool and discharge to obtain component A;

[0059] Preparation of component B: Put the vinyl-terminated polysiloxane with a viscosity of 100-1000 cSt, the hydrogen-containing silicone oil crosslinking agent with a viscosity of 2-100 cSt, and the inhibitor into a vacuum kneader for kneading treatment for 5-15 min, then add the heat-conductive filler composition modified by a silane coupling agent, continue kneading treatment for 0.5-2 h, remove low molecules and bubbles through vacuum degassing treatment, and cool and discharge to obtain component B;

[0060] In use, the A component and the B component are configured according to a molar ratio of Si-H / Si-Vi of (1.0-1.2):1, and the accurate A component and the B component are mixed uniformly to obtain the high-thermal-conductivity insulating silicone rubber composition for electric machines.

[0061] In the production and processing of the high-thermal-conductivity insulating silicone rubber composition for electric machines, the high-thermal-conductivity insulating silicone rubber composition is first punched in a forming mold, the forming mold is then placed in a magnetic field environment after the punching is completed, the magnetic field strength is 0.5-5T, the magnetic field direction is perpendicular to the horizontal plane, and the product is cured at room temperature for 8-12h, and then demolded to obtain the high-thermal-conductivity insulating silicone rubber product (sealing ring / shock pad) for electric machines with a smooth surface and no cracks.

[0062] Preparation Example 1: Preparation method of boron nitride whisker with surface-loaded magnetic Fe3O4

[0063] Step one: preparation of a precursor aqueous solution: FeCl·6H2O and FeCl·4H2O are dissolved in water according to a molar ratio of 2:1, and the obtained solution is uniformly mixed to obtain a total iron ion concentration of 0.3mol / L;

[0064] Step two: 50mL of the precursor aqueous solution with a total iron ion concentration of 0.3mol / L prepared in step one is added with 5g of boron nitride whisker XT-BN-X1, and the mixture is magnetically stirred at 200rpm for 3 hours, and then an ultrasonic vibration rod is installed, and ultrasonic dispersion treatment is performed at an ultrasonic frequency of 40kHz for 1 hour. After the ultrasonic dispersion treatment is completed, NH3·H2O is added in excess under nitrogen protection to form a black precipitate deposited on the outer wall of the boron nitride nanosheet. The pH value of the system is adjusted to 10, the water bath is warmed to 80℃, the magnetic stirring speed is adjusted to 600rpm, and the mixture is magnetically stirred for 1 hour and then cooled to room temperature. The mixture is filtered under reduced pressure, washed with distilled water for three times, and then vacuum filtered. Finally, the mixture is placed in a vacuum drying oven and vacuum dried at 105℃ for 2h to obtain the boron nitride whisker with surface-loaded magnetic Fe3O4.

[0065] Preparation Example 2: Preparation method of 3D graphene coated with Al2O3, including the following steps:

[0066] Step one: preparation of a sintered nano-silver precursor: 2.2g of 2-ethyl-4-methyl imidazole (CAS:931-36-2) and 1.67g of silver acetate (CAS:563-63-3) are added to 400mL of dichloromethane, and the mixture is magnetically stirred at 240r / min at room temperature until the silver acetate particles completely disappear to obtain an Ag(2E4MI)2Ac complex solution;

[0067] Step two, take 80 mL of Ag(2E4MI)2Ac complex solution into a 250 mL beaker, add 0.1 g of polyvinylpyrrolidone PVP and 4 g of 3D graphene TN3DRGO (Chengdu Institute of Organic Chemistry, Chinese Academy of Sciences) into the beaker, install an ultrasonic vibration rod, and perform ultrasonic dispersion treatment at an ultrasonic frequency of 40 kHz for 60 minutes to obtain a dispersion liquid;

[0068] Step three: the obtained dispersion liquid is subjected to reduced pressure distillation treatment to remove dichloromethane, and the obtained solid is sintered at 210℃ for 4 hours. After planetary ball milling treatment, the obtained solid is sieved with a 325 mesh and a 300 mesh to obtain 3D graphene agglomerate micro powder composed of nano-silver sintered 3D graphite with a particle size distribution of 300-325 mesh;

[0069] Step four, take 60 g of aluminum nitrate nonahydrate into a beaker and add 100 g of distilled water. Stir with a magnetic stirrer and heat to 70℃ until the aluminum nitrate is completely dissolved. Then, uniformly drop 20wt% of dissolved sodium carbonate into the aluminum nitrate solution, adjust the solution pH value to 5, and magnetically stir for 2h and stand for 24h to obtain an aluminum hydroxide sol with a Tyndall effect. Take 40 mL of the aluminum hydroxide sol in a 100 mL beaker, add 4 g of the 3D graphene agglomerate micro powder with a particle size distribution of 300-325 mesh prepared in step three into the 100 mL beaker containing the aluminum hydroxide sol, and stir at 240 r / min for 1h. Then, perform reduced pressure filtration treatment, wash the filter material with distilled water three times, and finally vacuum dry in a vacuum drying oven at 105℃ for 2h to obtain 3D graphene agglomerate micro powder coated with Al(OH)3 on the surface;

[0070] Step five, place the 3D graphene agglomerate micro powder coated with Al(OH)3 on the surface obtained in step four into an atmospheric tube furnace for calcination treatment. Heat to 900℃ at a rate of 20℃ / min under air atmosphere and calcine for 2h. Then, perform planetary ball milling treatment on the obtained sintered solid, and sieve with a 325 mesh and a 300 mesh to obtain 3D graphene coated with Al2O3 on the surface with a particle size distribution of 300-325 mesh.

[0071] Preparation example 3: preparation method of VGCF@Al2O3 type 3D graphene, steps as follows:

[0072] Step one, take 80 mL of the prepared Ag(2E4MI)2Ac complex solution in preparation example 2 into a 250 mL beaker, add 0.1 g of polyvinylpyrrolidone, 0.1 g of nanocarbon fiber VGCF (fiber diameter: 150-200 nm, length: 10-20 um, aspect ratio: 70) from Beijing Deke Island Gold Technology Co., Ltd. to the beaker, and install an ultrasonic vibration rod. Ultrasonic dispersion treatment is carried out at an ultrasonic frequency of 40 kHz for 2 h, then 4 g of 3D graphene agglomerate micropowder composed of nanosilver sintered 3D graphite with a particle size distribution of 300-325 mesh prepared in step three of preparation example 2 is added, and ultrasonic dispersion is continued at an ultrasonic frequency of 40 kHz for 1 h to obtain a dispersion liquid;

[0073] Step two, the obtained dispersion liquid is distilled under reduced pressure to remove dichloromethane to obtain a solid, and the solid is sintered at a high temperature of 210°C for 4 h to obtain a solid calcined material. The solid calcined material is subjected to planetary ball milling treatment, and then sieved with a 300 mesh and a 250 mesh to obtain a VGCF@Al2O3-coated 3D graphene with a particle size distribution of 250-300 mesh.

[0074] Example 1: An insulation high-thermal-conductivity type silicone rubber composition for electric machines is an A / B two-component addition type RTV silicone rubber. The molar ratio of Si-Vi in the A component to Si-H in the B component is 1:1.

[0075] The A component is made of the following raw materials by weight: 75 parts of a vinyl-terminated polydimethylsiloxane Andisil VS 200 (vinyl 0.25 mmoles / g) with a viscosity of 200 cSt, 24 parts of a vinyl-terminated polydimethylsiloxane Andisil VS 2000 (vinyl 0.08 mmoles / g) with a viscosity of 2000 cSt, 1 part of Karstedt platinum catalyst, and 35 parts of a heat-conducting filler composition modified by KH570.

[0076] The B component is made of the following raw materials by weight: 79.9 parts of a vinyl-terminated polydimethylsiloxane Andisil VS 500 (vinyl 0.15 mmoles / g) with a viscosity of 500 cSt, 15.1 parts of a hydrogen-containing silicone oil chain extender Andsil CE-13 (hydrogen content 1.37 mmoles / g) with a viscosity of 14 cSt, 4 parts of a hydrogen-containing silicone oil crosslinking agent Andsil XL-1340 (hydrogen content 3.00 mmoles / g) with a viscosity of 50 cSt, 1 part of ethynylcyclohexanol, and 50 parts of a heat-conducting filler composition modified by KH570.

[0077] The configuration method of the heat-conducting filler composition modified by KH570 is as follows:

[0078] Step one, 1 part by weight of surface-coated Al2O3 type 3D graphene in Preparation Example 2, 4 parts by weight of surface-loaded magnetic Fe3O4 boron nitride whisker in Preparation Example 1, 4 parts by weight of boron nitride whisker XT-BN-X1 (diameter: 0.3-0.5 μm, length: 10-20 μm) from Shanghai Xiangtian Nanometer Material Co., Ltd., 6 parts by weight of hexagonal boron nitride nanosheet Brofos-BN-W200 (average particle size 200 μm) from Bohua Snano Technology (Ningbo) Co., Ltd., and 85 parts by weight of spherical nanometer aluminum nitride YM-A1N-TCW120 (average particle size 120 μm) from Yumu (Ningbo) New Material Co., Ltd. are mixed and dispersed in a high-speed dispersion kettle at 400 rpm for 2 h to obtain a heat-conducting filler composition;

[0079] Meanwhile, a 1.0 wt% KH570 ethanol aqueous solution is configured: 1 part by weight of methacryloyloxy silane KH570 is uniformly mixed with 12 parts by weight of deionized water and 87 parts by weight of anhydrous ethanol;

[0080] Step two, 10 parts by weight of the heat-conducting filler composition prepared in step one is added to 200 mL of the 1.0 wt% KH570 ethanol aqueous solution, a 0.2 mol / L acetic acid aqueous solution is added dropwise to adjust the pH value of the system to 3.5, then magnetic stirring is performed at 200 r / min for 60 min, an ultrasonic vibration rod is installed, ultrasonic dispersion treatment is performed at an ultrasonic frequency of 40 kHz for 15 min, after the ultrasonic treatment is completed, reduced pressure filtration is performed, and the obtained filter material is placed in a vacuum drying oven for vacuum drying at 105°C for 2 h to obtain a KH570 modified heat-conducting filler composition.

[0081] A preparation method of an insulating high-thermal-conductivity type silicone rubber composition for a motor, comprising the following steps:

[0082] Preparation of component A: 75 parts of vinyl-terminated polydimethylsiloxane Andisil VS 200 with a viscosity of 200 cSt, 24 parts of vinyl-terminated polydimethylsiloxane Andisil VS 2000 with a viscosity of 2000 cSt, and 1 part by weight of Karstedt platinum catalyst are placed in a vacuum kneader and kneaded for 10 min, then 5*7 parts (35 parts) of the KH550 modified heat-conducting filler composition are added in five portions, the addition amount of the KH550 modified heat-conducting filler composition in each portion is 7 parts, after the addition of each portion is completed, the mixture is kneaded for 10 min, and then another portion of the KH550 modified heat-conducting filler composition is added, after the addition of 35 parts of the KH570 modified heat-conducting filler composition is completed, the mixture is continuously kneaded for 1 h, finally, vacuum degassing treatment is performed for 30 min to remove low molecular and bubbles, nitrogen is filled to restore normal pressure, and the mixture is cooled to room temperature, then discharged to obtain component A;

[0083] Preparation of B component: 79.9 parts of vinyl-terminated polydimethylsiloxane Andisil VS500 with a viscosity of 500 cSt, 15.1 parts of hydrogen-containing silicone oil chain extender Andsil CE-13 with a viscosity of 14 cSt, 4 parts of hydrogen-containing silicone oil crosslinking agent Andsil XL-1340 with a viscosity of 50 cSt, and 1 part of ethynylcyclohexanol were kneaded in a vacuum kneader for 10 min, and then 5*10 parts (50 parts) of the KH550-modified heat-conducting filler composition were added in five portions, with 10 parts of the KH550-modified heat-conducting filler composition added in each portion, and the mixture was kneaded for 15 min after each addition before adding another portion of the KH550-modified heat-conducting filler composition. After the addition of 50 parts of the KH550-modified heat-conducting filler composition was completed, the mixture was kneaded for another 1 h, and finally vacuum degassing was performed for 30 min to remove low-molecular substances and bubbles. Nitrogen was filled to restore normal pressure, and the mixture was cooled to room temperature. The B component was obtained after discharging.

[0084] In use, 135 parts by weight of the A component was mixed with 150 parts of the B component (molar ratio of Si-H / Si-Vi was 1:1) to obtain the motor insulation high-thermal-conductivity silicone rubber composition. The content of the KH570-modified heat-conducting filler composition in the obtained motor insulation high-thermal-conductivity silicone rubber composition was 29.82%.

[0085] The method for preparing the shock-absorbing sheet from the motor insulation high-thermal-conductivity silicone rubber composition was as follows:

[0086] Step one: 135 parts of the A component and 150 parts of the B component were put into a vacuum degassing stirrer, and mixed at a temperature of 10°C and a stirring speed of 240 rpm for 10 min, followed by vacuum degassing for 5 min to obtain the motor insulation high-thermal-conductivity silicone rubber composition.

[0087] The surface of the motor insulation high-thermal-conductivity shock-absorbing sheet was flat, and free of cracks, bubble holes, and pit defects. The thermal conductivity of the shock-absorbing sheet was 1.142 W / (m·K), and the volume resistivity was 10.29*10 13 Ω·m. After double 85 aging (85°C / 85%RH / 1000h), the thermal conductivity of the shock-absorbing sheet was 1.086 W / (m·K), and the volume resistivity was 9.66*10 13 Ω·m.

[0088] Example 2 differs from Example 1 in that the A component is made from 75 parts of a vinyl terminated polydimethylsiloxane Andisil VS 200 with a viscosity of 200 cSt, 24 parts of a vinyl terminated polydimethylsiloxane Andisil VS 2000 with a viscosity of 2000 cSt, 1 part of Karstedt's platinum catalyst, 27 parts of a KH570 modified heat conductive filler composition. The B component is made from 79.9 parts of a vinyl terminated polydimethylsiloxane Andisil VS 500 with a viscosity of 500 cSt, 15.1 parts of a hydrogen containing silicone oil chain extender Andsil CE-13 with a viscosity of 14 cSt, 4 parts of a hydrogen containing silicone oil crosslinker Andsil XL-1340 with a viscosity of 50 cSt, 1 part of ethynyl cyclohexanol, 40 parts of a KH570 modified heat conductive filler composition.

[0089] In use, 127 parts by weight of the A component is mixed with 140 parts of the B component (molar ratio of Si-H / Si-Vi is 1:1) to obtain the motor insulation high thermal conductive silicone rubber composition. The content of the KH570 modified heat conductive filler composition in the motor insulation high thermal conductive silicone rubber composition is 25.09%.

[0090] The surface of the insulation high thermal conductive shock absorbing sheet prepared using the insulation high thermal conductive silicone rubber composition of Example 2 is flat, without cracks, bubble holes, pit defects, the thermal conductivity is 1.002 W / (m-K), the volume resistivity is 13.76*10 13 Ω-m, the thermal conductivity after double 85 aging (85°C / 85%RH / 1000h) is 0.948 W / (m-K), the volume resistivity is 12.71*10 13 Ω-m.

[0091] Example 3 differs from Example 1 in that the A component is made from 75 parts of a vinyl terminated polydimethylsiloxane Andisil VS 200 with a viscosity of 200 cSt, 24 parts of a vinyl terminated polydimethylsiloxane Andisil VS 2000 with a viscosity of 2000 cSt, 1 part of Karstedt's platinum catalyst, 31 parts of a KH570 modified heat conductive filler composition. The B component is made from 79.9 parts of a vinyl terminated polydimethylsiloxane Andisil VS 500 with a viscosity of 500 cSt, 15.1 parts of a hydrogen containing silicone oil chain extender Andsil CE-13 with a viscosity of 14 cSt, 4 parts of a hydrogen containing silicone oil crosslinker Andsil XL-1340 with a viscosity of 50 cSt, 1 part of ethynyl cyclohexanol, 45 parts of a KH570 modified heat conductive filler composition.

[0092] In use, 131 parts by weight of the A component is mixed with 145 parts of the B component (molar ratio of Si-H / Si-Vi is 1:1) to obtain the motor insulation high-thermal-conductivity silicone rubber composition, and the content of the KH570 modified thermal conductive filler composition in the obtained motor insulation high-thermal-conductivity silicone rubber composition is 27.53%.

[0093] The insulation high-thermal-conductivity shock-absorbing sheet prepared from the insulation high-thermal-conductivity silicone rubber composition in Example 3 has a smooth surface, no cracks, bubble holes, pit defects, a thermal conductivity of 1.075 W / (m·K), and a volume resistivity of 12.29*10 13 Ω·m, and after double 85 aging (85℃ / 85%RH / 1000h), the thermal conductivity is 1.013 W / (m·K), and the volume resistivity is 11.45*10 13 Ω·m.

[0094] Example 4 differs from Example 1 in that in the preparation method of the KH570 modified thermal conductive filler composition, in Step 1, 2 parts by weight of the surface-coated Al2O3 type 3D graphene in Preparation Example 2, 5 parts by weight of the surface-loaded magnetic Fe3O4 boron nitride whisker in Preparation Example 1, 5 parts by weight of the boron nitride whisker XT-BN-X1, 8 parts by weight of the hexagonal boron nitride nanosheet Brofos-BN-W200, and 80 parts by weight of the spherical nanometer aluminum nitride YM-A1N-TCW120 are placed in a high-speed dispersion kettle and mixed and dispersed at 400 rpm for 2h to obtain the thermal conductive filler composition, and the rest is the same.

[0095] The insulation high-thermal-conductivity shock-absorbing sheet prepared from the insulation high-thermal-conductivity silicone rubber composition in Example 4 has a smooth surface, no cracks, bubble holes, pit defects, a thermal conductivity of 1.317 W / (m·K), and a volume resistivity of 9.69*10 13 Ω·m, and after double 85 aging (85℃ / 85%RH / 1000h), the thermal conductivity is 12.258 W / (m·K), and the volume resistivity is 9.11*10 13 Ω·m.

[0096] It can be known from the comparison between Example 1 and Example 4 that the content of the surface-coated Al2O3 type 3D graphene (1 part by weight→2 parts by weight) is increased, which is beneficial to improving the thermal conductivity of the insulation high-thermal-conductivity shock-absorbing sheet product, and the thermal conductivity is increased by 15.0%【1.142→1.317 W / (m·K)】, and the volume resistivity of the insulation high-thermal-conductivity shock-absorbing sheet product is still 9.69*10 13 Ω·m, and still has good insulation safety performance.

[0097] The difference between Example 5 and Example 1 is that in the preparation method of the KH570 modified heat-conducting filler composition, 0.5 parts by weight of the surface-coated Al2O3 type 3D graphene in Preparation Example 2, 3 parts by weight of the surface-loaded magnetic Fe3O4 boron nitride whisker in Preparation Example 1, 3 parts by weight of the boron nitride whisker XT-BN-X1, 4.5 parts by weight of the hexagonal boron nitride nanosheet Brofos-BN-W200, and 89 parts by weight of the spherical nanometer aluminum nitride YM-A1N-TCW120 are mixed and dispersed in a high-speed dispersion kettle at 400 rpm for 2 h to obtain the heat-conducting filler composition, and the rest is the same as in Example 1.

[0098] The surface of the insulating high-thermal-conductivity shock-absorbing sheet prepared from the insulating high-thermal-conductivity silicone rubber composition in Example 5 is flat, free of cracks, bubble holes, and pit defects, the thermal conductivity is 1.054 W / (m·K), and the volume resistivity is 11.24*10 13 Ω·m, the thermal conductivity after double 85 aging (85℃ / 85%RH / 1000h) is 0.993 W / (m·K), and the volume resistivity is 10.39*10 13 Ω·m.

[0099] As can be seen from the comparison between Example 1 and Example 5, the content of the surface-coated Al2O3 type 3D graphene (0.5 parts by weight→1 part by weight) is increased, which is beneficial to improving the thermal conductivity of the insulating high-thermal-conductivity shock-absorbing sheet product, and the thermal conductivity is increased by 8.35%【0.976→1.142 W / (m·K)】. As can be seen from Example 1 and Examples 4-5, the surface-coated Al2O3 type 3D graphene can control the thermal conductivity of the insulating high-thermal-conductivity shock-absorbing sheet, and meet the different needs of customers. For application scenarios with higher thermal conductivity, the thermal conductivity of the silicone rubber product can be further optimized by increasing the content of the surface-coated Al2O3 type 3D graphene in the KH570 modified heat-conducting filler composition.

[0100] The difference between Example 6 and Example 1 is that in the preparation method of the KH570 modified heat-conducting filler composition, 1 part by weight of the VGCF@surface-coated Al2O3 type 3D graphene with a particle size distribution of 250-300 mesh in Preparation Example 3, 4 parts by weight of the surface-loaded magnetic Fe3O4 boron nitride whisker in Preparation Example 1, 4 parts by weight of the boron nitride whisker XT-BN-X1, 6 parts by weight of the hexagonal boron nitride nanosheet Brofos-BN-W200, and 85 parts by weight of the spherical nanometer aluminum nitride YM-A1N-TCW120 are mixed and dispersed in a high-speed dispersion kettle at 400 rpm for 2 h to obtain the heat-conducting filler composition, and the rest is the same as in Example 1.

[0101] The surface of the insulating high-thermal-conductivity damping sheet prepared from the insulating high-thermal-conductivity silicone rubber composition in Example 6 is flat, free of cracks, bubble holes, and pit defects, the thermal conductivity is 1.285 W / (m·K), and the volume resistivity is 8.85*10 13 Ω·m, the thermal conductivity after double 85 aging (85℃ / 85%RH / 1000h) is 1.225 W / (m·K), and the volume resistivity is 8.33 10 13 Ω·m.

[0102] As can be seen from the comparison between Example 1 and Example 6, the Al2O3 type 3D graphene outer wall is grafted with nanocarbon fiber VGCF by means of nanosilver sintering, the VGCF branched Al2O 3@ The 3D graphene is conducive to constructing a more efficient multi-dimensional three-dimensional thermal conduction network structure, and improving the thermal conductivity of the silicone rubber product.

[0103] The difference between Comparative Example 1 and Example 1 is that the KH570 modified thermal conductive filler composition in components A and B is replaced by KH570 modified spherical nanometer aluminum nitride.

[0104] The configuration method of the KH570 modified spherical nanometer aluminum nitride is as follows:

[0105] Step one, prepare a 1.0wt% KH570 ethanol aqueous solution: mix 1 part by weight of methacryloxy silane KH570 with 12 parts by weight of deionized water and 87 parts by weight of anhydrous ethanol;

[0106] Step two, take 10 parts by weight of spherical nanometer aluminum nitride YM-A1N-TCW120 and add it to 200mL of the 1.0wt% KH570 ethanol aqueous solution, add a 0.2mol / L acetic acid aqueous solution dropwise to adjust the pH value of the system to 3.5, then magnetically stir at 200r / min for 60 minutes, install an ultrasonic vibration rod, and perform ultrasonic dispersion treatment at an ultrasonic frequency of 40kHz for 15 minutes, after the ultrasonic treatment, perform reduced pressure filtration, and place the obtained filter material in a vacuum drying oven for vacuum drying at 105℃ for 2h to obtain the KH570 modified spherical nanometer aluminum nitride.

[0107] The surface of the insulating high-thermal-conductivity damping sheet prepared from the insulating high-thermal-conductivity silicone rubber composition in Comparative Example 1 is flat, free of cracks, bubble holes, and pit defects, the thermal conductivity is 0.824 W / (m·K), and the volume resistivity is 20.19*10 13 Ω·m, the thermal conductivity after double 85 aging (85℃ / 85%RH / 1000h) is 0.754 W / (m·K), and the volume resistivity is 18.18*10 13 Ω·m.

[0108] Compared with Example 1 and Comparative Example 1, it can be seen that only using conventional spherical nano-aluminum nitride as an insulating high-thermal-conductivity filler, the thermal conductivity of the prepared insulating high-thermal-conductivity damping sheet is less than 0.85 W / (m·K). The thermal conductivity of the insulating high-thermal-conductivity damping sheet prepared by using the thermal conductive filler composition modified by KH570 in Example 1 increases by 38.6%

(0.824→1.142 W / (m·K)

[0109] Comparative Example 2 and Example 1 differ in that the step one in the preparation method of the thermal conductive filler composition (not containing surface-loaded magnetic Fe3O4 boron nitride whisker) is that 1 part by weight of the surface-coated Al2O3 type 3D graphene in Preparation Example 2, 8 parts by weight of boron nitride whisker XT-BN-X1, 6 parts by weight of hexagonal boron nitride nanosheet Brofos-BN-W200, and 85 parts by weight of spherical nano-aluminum nitride YM-A1N-TCW120 are placed in a high-speed dispersion kettle and mixed and dispersed at 400 rpm for 2 h to obtain the thermal conductive filler composition, and the remaining steps are the same.

[0110] The insulating high-thermal-conductivity damping sheet prepared by using the insulating high-thermal-conductivity silicone rubber composition in Comparative Example 2 has a smooth surface, no cracks, bubble holes, pit defects, a thermal conductivity of 0.927 W / (m·K), a volume resistivity of 14.23*10 13 Ω·m, a thermal conductivity of 0.876 W / (m·K) after double 85 aging (85℃ / 85%RH / 1000h), and a volume resistivity of 13.17*10 13 Ω·m.

[0111] Compared with Example 1 and Comparative Example 2, it can be seen that after replacing the surface-loaded magnetic Fe3O4 boron nitride whisker with an equal amount of boron nitride whisker XT-BN-X1, the thermal conductivity of the prepared insulating high-thermal-conductivity damping sheet decreases by 18.8%

(1.142→0.927 W / (m·K)

[0112] The difference between Comparative Example 3 and Example 1 is that in the preparation method of the heat-conducting filler composition (not containing the surface-coated Al2O3 type 3D graphene) modified by KH570, 4 parts by weight of the surface-loaded magnetic Fe3O4 boron nitride whisker in Preparation Example 1, 4 parts by weight of boron nitride whisker XT-BN-X1, 6 parts by weight of hexagonal boron nitride nanosheet Brofos-BN-W200, and 86 parts by weight of spherical nanometer aluminum nitride YM-A1N-TCW120 are mixed and dispersed in a high-speed dispersion kettle at 400 rpm for 2 h to obtain the heat-conducting filler composition, and the remaining steps are the same.

[0113] The surface of the insulating high-thermal-conductivity shock-absorbing sheet prepared from the insulating high-thermal-conductivity silicone rubber composition in Comparative Example 3 is flat, free of cracks, bubble holes, and pit defects, has a thermal conductivity of 0.948 W / (m·K), and a volume resistivity of 15.64*10 13 Ω·m, and after double 85 aging (85℃ / 85%RH / 1000h), the thermal conductivity is 0.893 W / (m·K), and the volume resistivity is 14.42*10 13 Ω·m.

[0114] As can be seen from the comparison between Example 1 and Comparative Example 3, the addition of the surface-coated Al2O3 type 3D graphene helps to improve the thermal conductivity of the silicone rubber product, and as the amount of the surface-coated Al2O3 type 3D graphene decreases from 1 part by weight to 0 part by weight, the thermal conductivity of the silicone rubber shock-absorbing sheet decreases by 17.0%

(1.142→0.948 W / (m·K)

[0115] The difference between Comparative Example 4 and Example 1 is that in the preparation method of the heat-conducting filler composition (not containing the surface-loaded magnetic Fe3O4 boron nitride whisker and boron nitride whisker) modified by KH570, 1 part by weight of the surface-coated Al2O3 type 3D graphene in Preparation Example 2, 6 parts by weight of hexagonal boron nitride nanosheet Brofos-BN-W200, and 93 parts by weight of spherical nanometer aluminum nitride YM-A1N-TCW120 are placed in a high-speed dispersion kettle and mixed and dispersed at 400 rpm for 2 h to obtain the heat-conducting filler composition, and the remaining steps are the same.

[0116] The surface of the insulating high-thermal-conductivity shock-absorbing sheet prepared from the insulating high-thermal-conductivity silicone rubber composition in Comparative Example 4 is flat, free of cracks, bubble holes, and pit defects, has a thermal conductivity of 0.886 W / (m·K), and a volume resistivity of 17.15*10 130.821 W / (m·K), and the volume resistivity was 15.83*10 13 Ω·m.

[0117] As can be seen from the comparison of Example 1 and Comparative Examples 2 and 4, the replacement of the rod-shaped insulating and heat-conducting filler composition with an equal amount of spherical nano-aluminum nitride YM-A1N-TCW120, i.e., the absence of the rod-shaped insulating and heat-conducting filler composition in the insulating and high-thermal-conductivity silicone rubber composition, the thermal conductivity of the silicone rubber damping sheet decreased by 22.4%

(1.142→0.886 W / (m·K)

[0118] Comparative Example 5 differs from Example 1 in that the preparation method of the heat-conducting filler composition (containing no hexagonal boron nitride nanosheet) modified by KH570 in Step 1 is as follows: 1 part by weight of the surface-coated Al2O3 type 3D graphene in Preparation Example 2, 4 parts by weight of the surface-loaded magnetic Fe3O4 boron nitride whisker in Preparation Example 1, 4 parts by weight of boron nitride whisker XT-BN-X1, and 91 parts by weight of spherical nano-aluminum nitride YM-A1N-TCW120 are mixed and dispersed in a high-speed dispersion kettle at 400 rpm for 2 h to obtain the heat-conducting filler composition, and the remaining steps are the same.

[0119] The insulating and high-thermal-conductivity damping sheet prepared from the insulating and high-thermal-conductivity silicone rubber composition in Comparative Example 5 has a smooth surface, no cracks, bubble holes, and pit defects, a thermal conductivity of 0.969 W / (m·K), and a volume resistivity of 12.64*10 13 Ω·m, and a thermal conductivity of 0.910 W / (m·K) and a volume resistivity of 11.65*10 13 Ω·m after double 85 aging (85℃ / 85%RH / 1000h).

[0120] As can be seen from the comparison of Example 1 and Comparative Example 5, the addition of the hexagonal boron nitride nanosheet can improve the thermal conductivity of the silicone rubber product, i.e., the absence of the hexagonal boron nitride nanosheet in the insulating and high-thermal-conductivity silicone rubber composition, the thermal conductivity of the silicone rubber damping sheet decreased by 15.1%

(1.142→0.969 W / (m·K)

[0121] The difference between Comparative Example 6 and Example 1 is that in step one of the preparation method of the KH570 modified thermally conductive filler composition, 1 part by weight of 3D graphene agglomerate powder composed of 300-325 mesh nano-silver sintered 3D graphite in Preparation Example 2, 4 parts by weight of boron nitride whiskers with surface magnetic Fe3O4 in Preparation Example 1, 4 parts by weight of boron nitride whiskers XT-BN-X1, 6 parts by weight of hexagonal boron nitride nanosheets Brofos-BN-W200, and 85 parts by weight of spherical nano-aluminum nitride YM-A1N-TCW120 are placed in a high-speed dispersion vessel and mixed and dispersed at 400 rpm for 2 hours to obtain the thermally conductive filler composition. The remaining steps are the same.

[0122] The insulating and thermally conductive damping sheet prepared using the insulating and thermally conductive silicone rubber composition in Comparative Example 6 has a smooth surface, free from cracks, bubbles, and pits. Its thermal conductivity is 1.282 W / (m·K), and its volume resistivity is 3.56 × 10⁻⁶. 10 The thermal conductivity after aging at 85℃ / 85%RH / 1000h is 1.218 W / (m·K), and the volume resistivity is 3.19 × 10⁻⁶ Ω·m. 10 Ω·m.

[0123] A comparison of Example 1 and Comparative Example 6 shows that while using 3D graphene aggregate micropowder without Al2O3 coating improves the thermal conductivity of silicone rubber products better, it leads to a significant decrease in the volume resistivity of the silicone rubber products, and the insulation safety performance cannot meet the requirements of silicone rubber products for motors. Therefore, 3D graphene materials with Al2O3 coating can effectively improve the thermal conductivity of silicone rubber products while ensuring that the silicone rubber products still maintain good electrical insulation safety performance.

[0124] The difference between Comparative Example 7 and Example 1 is that: Component A is composed of 75 parts of vinyl-terminated polydimethylsiloxane Andisil VS 200 (viscosity 200 cSt), 24 parts of vinyl-terminated polydimethylsiloxane Andisil VS2000 (viscosity 2000 cSt), 1 part of Karstedt platinum catalyst, and 20 parts of KH570 modified thermally conductive filler composition. Component B is composed of 79.9 parts of vinyl-terminated polydimethylsiloxane Andisil VS 500 (viscosity 500 cSt), 15.1 parts of hydrogen-containing silicone oil chain extender Andsil CE-13 (viscosity 14 cSt), 4 parts of hydrogen-containing silicone oil crosslinking agent Andsil XL-1340 (viscosity 50 cSt), 1 part of ethynylcyclohexanol, and 30 parts of KH570 modified thermally conductive filler composition.

[0125] In use, 120 parts by weight of the A component is mixed with 130 parts of the B component (molar ratio of Si-H / Si-Vi is 1:1) to obtain the motor insulation high-thermal-conductivity silicone rubber composition, and the content of the KH570 modified thermal conductive filler composition in the obtained motor insulation high-thermal-conductivity silicone rubber composition is 20%.

[0126] The insulation high-thermal-conductivity damping sheet prepared from the insulation high-thermal-conductivity silicone rubber composition in Comparative Example 7 has a smooth surface, no cracks, bubble holes, pit defects, a thermal conductivity of 0.612 W / (m·K), and a volume resistivity of 16.21*10 13 Ω·m, and after double 85 aging (85℃ / 85%RH / 1000h), the thermal conductivity is 0.548 W / (m·K), and the volume resistivity is 14.52*10 13 Ω·m.

[0127] Comparative Example 8 differs from Example 1 in that the A component is made of 75 parts of a vinyl-terminated polydimethylsiloxane Andisil VS 200 with a viscosity of 200 cSt, 24 parts of a vinyl-terminated polydimethylsiloxane Andisil VS 2000 with a viscosity of 2000 cSt, 1 part of a Karstedt platinum catalyst, and 44 parts of a KH570 modified thermal conductive filler composition. The B component is made of 79.9 parts of a vinyl-terminated polydimethylsiloxane Andisil VS 500 with a viscosity of 500 cSt, 15.1 parts of a hydrogen-containing silicone oil chain extender Andsil CE-13 with a viscosity of 14 cSt, 4 parts of a hydrogen-containing silicone oil crosslinking agent Andsil XL-1340 with a viscosity of 50 cSt, 1 part of an ethynylcyclohexanol, and 64 parts of a KH570 modified thermal conductive filler composition.

[0128] In use, 144 parts by weight of the A component is mixed with 164 parts of the B component (molar ratio of Si-H / Si-Vi is 1:1) to obtain the motor insulation high-thermal-conductivity silicone rubber composition, and the content of the KH570 modified thermal conductive filler composition in the obtained motor insulation high-thermal-conductivity silicone rubber composition is 35.06%.

[0129] The insulation high-thermal-conductivity damping sheet prepared from the insulation high-thermal-conductivity silicone rubber composition in Comparative Example 8 has partial pit defects on the side surface and uneven surface at the corners, which indicates that a high content of the KH570 modified thermal conductive filler composition leads to poor flowability and poor die effect, and surface smoothness problems are prone to occur. The insulation high-thermal-conductivity damping sheet has a thermal conductivity of 1.224 W / (m·K) and a volume resistivity of 8.64*10 13Ω·m, the thermal conductivity of the insulation high thermal conductive damping sheet prepared by the insulation high thermal conductive silicone rubber composition of the present application is 1.171 W / (m·K) and the volume resistivity is 8.15*10 13 Ω·m.

[0130] As can be seen from the comparison of Examples 1-3 and Comparative Examples 7-8, when the filling amount of the thermal conductive filler composition modified by KH570 is 25-30 wt%, the insulation high thermal conductive silicone rubber composition has good mold filling effect, the surface of the insulation high thermal conductive damping sheet is flat, and there are no cracks, bubble holes, pit defects, and the yield is high. As can be seen from the trend chart of the filling amount (20-35%) of the thermal conductive filler composition modified by KH570 and the thermal conductivity of the prepared insulation high thermal conductive damping sheet, when the filling amount of the thermal conductive filler composition modified by KH570 is controlled to be 26-30%, the thermal conductivity of the insulation high thermal conductive damping sheet is ≥1 W / (m·K) and the volume resistivity is ≥10 14 Ω·m.

[0131] The difference between Comparative Example 9 and Example 1 is that the A component is made of 99 parts of vinyl-terminated polydimethylsiloxane Andisil VS 2000 (vinyl 0.08 mmoles / g) with a viscosity of 2000 cSt, 1 part of Karstedt platinum gold catalyst, and 35 parts of the thermal conductive filler composition modified by KH570.

[0132] The B component is made of the following raw materials in parts by weight: 86.7 parts of vinyl-terminated polydimethylsiloxane Andisil VS 500 (vinyl 0.15 mmoles / g) with a viscosity of 500 cSt, 9.8 parts of hydrogen-containing silicone oil chain extender Andsil CE-13 (hydrogen content 1.37 mmoles / g) with a viscosity of 14 cSt, 2.5 parts of hydrogen-containing silicone oil crosslinking agent Andsil XL-1340 (hydrogen content 3.00 mmoles / g) with a viscosity of 50 cSt, 1 part of ethynylcyclohexanol, and 50 parts of the thermal conductive filler composition modified by KH570.

[0133] As can be seen from the fact that the side of the insulation high thermal conductive damping sheet prepared by the insulation high thermal conductive silicone rubber composition in Comparative Example 9 has pit defects and the corners of the surface are not flat, the viscosity of the vinyl-terminated polydimethylsiloxane can affect the flowability of the final insulation high thermal conductive silicone rubber composition. The use of vinyl-terminated polydimethylsiloxane with a viscosity of 2000 cSt and vinyl-terminated polydimethylsiloxane with a viscosity of 200 cSt can improve the flowability of the insulation high thermal conductive silicone rubber composition, improve the mold filling effect, and avoid the problem of surface flatness of the insulation high thermal conductive damping sheet. The thermal conductivity of the insulation high thermal conductive damping sheet is 1.012 W / (m·K) and the volume resistivity is 10.05*10 13Ω·m, the thermal conductivity of which after double 85 aging (85℃ / 85%RH / 1000h) is 0.954 W / (m·K), and the volume resistivity is 9.36*10 13 Ω·m.

[0134] As can be seen from the comparison between Embodiment 1 and Comparative Example 9, under the premise that the molar ratio of Si-H / Si-Vi is 1:1, the high-viscosity silicone rubber composition formed by mixing the A / B components will limit the directional arrangement movement of the surface-loaded magnetic Fe3O4 boron nitride whiskers under the action of magnetic force, resulting in a decrease of 11.4% (1.142→1.012) in the thermal conductivity of the silicone rubber damping sheet, that is, the vertically arranged surface-loaded magnetic Fe3O4 boron nitride whiskers are conducive to the construction of a more efficient multidimensional three-dimensional thermal conduction network structure, and the thermal conductivity of the silicone rubber product is improved.

[0135] In summary, the present application can form a more efficient multidimensional three-dimensional thermal conduction network structure with 25-30wt% of the insulating and heat-conducting filler composition, and the insulating and high-thermal-conducting silicone rubber composition product has good thermal conductivity and electrical insulation performance, and the problem of surface defects of the product caused by the high filling amount of the insulating and heat-conducting filler in the existing two-component addition type RTV silicone rubber for the production of motor sealing rings / damping sheets is solved.

[0136] It should be noted that the specific embodiments are only used to explain and describe the technical solutions of the present application, and are not a limitation of the present application. Those skilled in the art can make modifications to the embodiments without creative contribution after reading the present specification, as long as the modifications are within the scope of the claims of the present application.

Claims

1. An electric motor insulation high thermal conductive type silicone rubber composition is A / B two-component addition type RTV silicone, characterized in that: The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix.

2. The insulating high thermal conductive silicone rubber composition for electric machines according to claim 1, characterized by: The insulating and heat-conducting filler composition is composed of surface-coated graphene, spherical insulating and heat-conducting fillers, rod-shaped insulating and heat-conducting fillers, and flaky insulating and heat-conducting fillers; the rod-shaped insulating and heat-conducting filler composition is composed of rod-shaped insulating and heat-conducting fillers and magnetic rod-shaped insulating and heat-conducting fillers; the surface-coated graphene accounts for 0.10-2.0 wt% of the total mass of the insulating and heat-conducting filler composition; the spherical insulating and heat-conducting fillers account for 75-90 wt% of the total mass of the insulating and heat-conducting filler composition.

3. The insulating high thermal conductive silicone rubber composition for electric machines according to claim 2, characterized by: The mass ratio of the rod-shaped insulating and heat-conducting fillers to the magnetic rod-shaped insulating and heat-conducting fillers is 1:(0.5-2).

4. The insulating high thermal conductive silicone rubber composition for electric machines according to claim 2, characterized by: The magnetic rod-shaped insulating and heat-conducting fillers are insulating and heat-conducting whiskers with surface-loaded magnetic Fe3O4; the rod-shaped insulating and heat-conducting fillers are insulating and heat-conducting whiskers with OD of 0.1-5 μm and L of 5-100 μm.

5. The insulating high thermal conductive silicone rubber composition for electric machines according to claim 4, characterized by: The magnetic rod-shaped insulating and heat-conducting fillers are boron nitride whiskers with surface-loaded magnetic Fe3O4; the rod-shaped insulating and heat-conducting fillers are boron nitride whiskers; the mass ratio of the rod-shaped insulating and heat-conducting fillers to the magnetic rod-shaped insulating and heat-conducting fillers is 1:

1.

6. The insulating high thermal conductive silicone rubber composition for electric machines according to claim 4, characterized by: The surface-coated graphene comprises a graphene body and an insulating and heat-conducting coating layer coated on the graphene body, and the insulating and heat-conducting coating layer is made of any one of aluminum oxide particles, aluminum nitride particles, boron nitride particles, titanium nitride particles, and silicon nitride particles through in-situ polymerization or self-assembly.

7. The insulating high thermal conductive silicone rubber composition for electric machines according to claim 2, characterized by: The spherical insulating and heat-conducting fillers are at least one of spherical or near-spherical nano-aluminum oxide, nano-aluminum nitride, nano-boron nitride, nano-titanium nitride, and nano-silicon nitride.

8. The insulating high thermal conductive silicone rubber composition for electric machines according to claim 2, characterized by: The flaky insulating and heat-conducting fillers are at least one of aluminum nitride nanosheets and boron nitride nanosheets.

9. The insulating high thermal conductive silicone rubber composition for electric machines according to claim 1, characterized by: The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix.

10. A process for preparing an electric machine insulation high thermal conductivity silicone rubber composition according to any one of claims 1 to 9, characterized by: The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fillers arranged in the silicone rubber matrix. The A / B two-component addition type RTV silicone glue comprises 25-30 wt% of an insulating and heat-conducting filler composition, which comprises magnetic rod-shaped insulating and heat-conducting fill Preparation of A component: vinyl terminated polysiloxane with viscosity of 50-500 cSt, vinyl terminated polysiloxane with viscosity of 500-5000 cSt, platinum gold catalyst are put into a vacuum kneader for kneading treatment for 5-15 min, then the heat conductive filler composition modified by silane coupling agent is added, and the kneading treatment is continued for 0.5-2 h, and the low molecular and bubbles are removed by vacuum defoaming treatment, and the product is discharged after cooling to obtain A component; Preparation of B component: vinyl terminated polysiloxane with viscosity of 100-1000 cSt, hydrogen-containing silicone oil crosslinking agent with viscosity of 2-100 cSt, inhibitor are put into a vacuum kneader for kneading treatment for 5-15 min, then the heat conductive filler composition modified by silane coupling agent is added, and the kneading treatment is continued for 0.5-2 h, and the low molecular and bubbles are removed by vacuum defoaming treatment, and the product is discharged after cooling to obtain B component; In use, A component and B component are configured according to the molar ratio of Si-H / Si-Vi of (1.0-1.2):1, and the accurate A component and B component are mixed uniformly to obtain the insulating high-thermal-conductivity silicone rubber composition for electric machines.