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EP-4741459-A1 - THERMALLY CONDUCTIVE SILICONE RUBBER AND PREPARATION METHOD THEREFOR

EP4741459A1EP 4741459 A1EP4741459 A1EP 4741459A1EP-4741459-A1

Abstract

The present invention relates to the technical field of thermally conductive silicone rubber, and specifically to a thermally conductive silicone rubber and preparation method thereof. The present invention proposes a thermally conductive silicone rubber and preparation method thereof. The thermally conductive silicone rubber comprises: vinyl terminated polydimethylsiloxane, vinyl MQ silicone resin, hydrogen-containing silicone oil, ethynyl cyclohexanol, and modified silver powder; wherein, the modified silver powder is a mixture containing silicone resin and silver powder. In the thermally conductive silicone rubber provided by the present invention, by using silver powder coated with silicone resin, the thermally conductive silicone rubber of the present invention has appropriate fluidity before curing and a high thermal conductivity, such that it can meet the market demand for the silicone rubber with ultra-high thermal conductivity. The thermally conductive silicone rubber provided by the present invention may be applied to heat dissipation components of structures such as light-emitting chips with ultra-high power, etc.

Inventors

  • LI, ZHENZHONG
  • WANG, YILIN
  • DENG, Zuozhu

Assignees

  • Beijing KMT Technology Co., Ltd.

Dates

Publication Date
20260513
Application Date
20250901

Claims (11)

  1. A thermally conductive silicone rubber, characterized in that , the thermally conductive silicone rubber comprises: vinyl terminated polydimethylsiloxane, vinyl MQ silicone resin, hydrogen-containing silicone oil, ethynyl cyclohexanol, modified silver powder; wherein the modified silver powder is a mixture containing silicone resin and silver powder.
  2. The thermally conductive silicone rubber of claim 1, characterized in that , the thermally conductive silicone rubber has a thermal conductivity of 10-18 W/(m•K); the cured thermally conductive silicone rubber has a hardness of 50-95 A; and at a temperature of 25 °C and a shear rate of 0.2 S -1 , the thermally conductive silicone rubber has a shear viscosity of 60000-100000 mPa•s.
  3. The thermally conductive silicone rubber of claim 1 or 2, characterized in that , at a temperature of 25 °C, the vinyl terminated polydimethylsiloxane has a dynamic viscosity of 200-500000 mPa•s, preferably 3000-20000 mPa•s; and/or, the vinyl MQ silicone resin has a vinyl content of 0.0006-0.002 mol/g; and/or, a molar ratio of M units to Q units in the vinyl MQ silicone resin is 0.9-1.1.
  4. The thermally conductive silicone rubber of claim 1 or 2, characterized in that , the silicone rubber comprises: 60-80 parts by mass of vinyl terminated polydimethylsiloxane, 20-40 parts by mass of vinyl MQ silicone resin, 3-5 parts of hydrogen-containing silicone oil, 0.008-0.012 parts of ethynyl cyclohexanol, and 350-700 parts of modified silver powder.
  5. The thermally conductive silicone rubber of any one of claims 1-3, characterized in that , a mass content of hydrogen in the hydrogen-containing silicone oil is 1.1% to 1.3%; and/or, at a temperature of 25°C, the hydrogen-containing silicone oil has a dynamic viscosity of 10-200 mPa•s, preferably 15-50 mPa•s.
  6. The thermally conductive silicone rubber of any one of claims 1-5, characterized in that , the modified silver powder comprises 4-6 parts by mass of silicone resin and 80-120 parts by mass of silver powder.
  7. The thermally conductive silicone rubber of claim 6, characterized in that , a method for preparing the modified silver powder comprises: mixing the silicone resin, a solvent, and the silver powder, drying the resultant, and grinding to obtain the modified silver powder; wherein, preferably, the solvent is toluene; preferably, the silver powder has a D50 value of 1-5 µm; and preferably, a time for the grinding is 8-10 h.
  8. The thermally conductive silicone rubber of any one of claims 1-7, characterized in that , the silicone resin has a softening point of 60-70°C; and/or, the silicone resin is a reaction product of octamethylcyclotetrasiloxane, diphenyldimethoxysilane, and phenyltrimethoxysilane; and preferably, a mass ratio of the octamethylcyclotetrasiloxane, diphenyldimethoxysilane, and phenyltrimethoxysilane may be 120-140:420-460:800-1200.
  9. The thermally conductive silicone rubber of claim 8, characterized in that , a method for preparing the silicone resin comprises: (1) mixing and stirring the octamethylcyclotetrasiloxane, diphenyldimethoxysilane, phenyltrimethoxysilane, toluene, concentrated sulfuric acid, and water to obtain a mixed solution; (2) allowing the mixed solution to stand to separate into an oil layer and a water layer, discarding the water layer, adjusting pH value of the oil layer, and filtering the resultant, drying, and crushing to obtain the silicone resin; wherein, preferably, the water is deionized water or distilled water; preferably, the concentrated sulfuric acid has a concentration of 97 wt% to 99 wt%; preferably, the stirring is stirring at reflux, and the stirring at reflux is performed under conditions of: at a temperature of 70-80°C for 5-7 h; and/or, the pH value of the oil layer is adjusted to 6.5-7.5.
  10. A method for preparing the thermally conductive silicone rubber of any one of claims 1 to 9, characterized in that , the method comprises: mixing the vinyl terminated polydimethylsiloxane, vinyl MQ silicone resin, hydrogen-containing silicone oil, ethynyl cyclohexanol, and modified silver powder in the presence of a catalyst to obtain the thermally conductive silicone rubber.
  11. The method for preparing the thermally conductive silicone rubber of claim 10, characterized in that , the catalyst is a platinum complex, and the catalyst is used in an amount that a mass of platinum is 15-40 ppm of a total mass of other components in the thermally conductive silicone rubber except for the modified silver powder; and/or, a time for the mixing is 0.2-0.5 h.

Description

Cross Reference to Related Applications The present application claims the priority of Chinese Patent Application No. 202411206803.2 entitled "A thermally conductive silicone rubber and preparation method thereof" and filed on August 30, 2024, the entire content of which is incorporated herein by reference. Field of the Invention The present invention relates to the technical field of thermally conductive silicone rubber, specifically to a thermally conductive silicone rubber and preparation method thereof. Background of the Invention In prior art, a thermally conductive silicone rubber generally comprises polysiloxane as a base material and is filled with metal oxides as fillers. At present, the thermally conductive silicone rubber generally has a thermal conductivity of 0.5-8 W/(m•K). With continuous change in market demand, the requirements for the thermal conductivity of the thermally conductive silicone rubber has been increasingly improved. In order to meet the market demand, it is necessary to develop a silicone rubber with higher thermal conductivity. In the current research, it is attempted to fill the silicone rubber with metal (such as copper, silver, nickel, etc.) powders to improve the thermal conduction performance of the silicone rubber. However, due to the properties of the metal powders per se, adding metal powders to improve the thermal conductivity of the thermally conductive silicone rubber may result in that the fluidity of the thermally conductive silicone rubber before curing cannot meet the use requirements; or, the addition of metal powders will make the viscosity of the thermally conductive silicone rubber too high. These factors will make the preparation of the thermally conductive silicone rubber difficult or will limit the application fields of the thermally conductive silicone rubber. Therefore, at present, it is necessary to provide a silicone rubber with fluidity before curing and high thermal conductivity. Summary of the Invention In order to solve the above-mentioned problems in the prior art, the present invention provides a thermally conductive silicone rubber and preparation method thereof. In a first aspect, the present invention provides a thermally conductive silicone rubber, comprising: vinyl terminated polydimethylsiloxane, vinyl MQ silicone resin, hydrogen-containing silicone oil, ethynyl cyclohexanol, and modified silver powder; wherein, the modified silver powder is a mixture containing silicone resin and silver powder. As a specific embodiment of the present invention, at a temperature of 25 °C and a shear rate of 0.2S-1, the thermally conductive silicone rubber of the present invention has a shear viscosity of 60000-100000 mPa•s. For example, the shear viscosity of the thermally conductive silicone rubber may be 60000 mPa•s, 70000 mPa•s, 80000 mPa•s, 90000 mPa•s, 100000 mPa•s, or within a range defined by the aforementioned values. The shear viscosity of the thermally conductive silicone rubber in the present invention is tested by adopting a rheometer with a model of MCR102 from Anton Paar company. As a specific embodiment of the present invention, the thermally conductive silicone rubber has a thermal conductivity of 10-18 W/(m•K), for example, the thermal conductivity of the thermally conductive silicone rubber may be 10 W/(m•K), 11 W/(m•K), 12 W/(m•K), 13 W/(m•K), 14 W/(m•K), 15 W/(m•K), 16 W/(m•K), 17 W/(m•K), 18 W/(m•K), or within a range defined by the aforementioned values. In the present invention, the thermal conductivity of thermally conductive silicone rubber is tested by adopting a thermal conductometer with a model of TPS 500S from Hot Disk company, by using a transient plane heat source method. As a specific embodiment of the present invention, as tested according to GBT 2411-2008 standard, the cured thermally conductive silicone rubber of the present invention has a hardness of 50-95 A. For example, the hardness of the cured thermally conductive silicone rubber is 50 A, 60 A, 70 A, 80 A, 90 A, 95 A, or within a range defined by the aforementioned values. As a specific embodiment of the present invention, at a temperature of 25°C, the vinyl terminated polydimethylsiloxane has a dynamic viscosity of 200-500000 mPa•s, for example, the dynamic viscosity may be 200 mPa•s, 500 mPa•s, 1000 mPa•s, 1500 mPa•s, 2000 mPa•s, 3000 mPa•s, 4000 mPa•s, 5000 mPa•s, 6000 mPa•s, 7000 mPa•s, 8000 mPa•s, 9000 mPa•s, 10000 mPa•s, 15000 mPa•s, 20000 mPa•s, 25000 mPa•s, 30000 mPa•s, 35000 mPa•s, 40000 mPa•s, 45000 mPa•s, 50000 mPa•s, 100000 mPa•s, 200000 mPa•s, 300000 mPa•s, 400000 mPa•s, 500000 mPa•s, or within a range defined by the aforementioned values, and preferably within a range of 3000-20000 mPa•s. The dynamic viscosity of the vinyl terminated polydimethylsiloxane is tested by adopting a Brookfield viscometer with a model of DV2TRV from USA Brookfield company. As a specific embodiment of the present invention, the vinyl MQ silicone resin has M units and Q unit