JP-2026075046-A - Thermally conductive silicone composition

Abstract

[Problem] To provide a thermally conductive silicone composition that can satisfy both weight reduction and storage stability even when using aluminum hydroxide filler. [Solution] The thermally conductive silicone composition is a thermally conductive filler selected from (A) an alkenyl group-containing diorganopolysiloxane bonded to a silicon atom, (B) a diorganopolysiloxane having a hydrogen atom bonded to a silicon atom, and (C) aluminum oxide (C1) with an average particle size of less than 5 μm and a hot water-extracted sodium oxide content of less than 300 ppm, as quantified by atomic absorption spectrometry, and aluminum hydroxide with an average particle size of less than 5 μm and a hot water-extracted sodium oxide content of less than 70 ppm, as quantified by atomic absorption spectrometry. The material comprises: (D) a first thermally conductive filler in the amount of 30 to 220 parts by mass per 100 parts by mass of the total of component (A) and component (B); (E) a second thermally conductive filler in the amount of 400 to 950 parts by mass per 100 parts by mass of the total of component (A) and component (B), wherein the hot water extracted sodium oxide content is less than 70 ppm as quantified by atomic absorption spectrometry, and the average particle size is 5 μm to 100 μm; and (E) an addition catalyst in the amount of 0.2 to 1.0 parts by mass per 100 parts by mass of the total of component (A) and component (B). [Selection Diagram] None

Inventors

• 武田 悠一郎
• 山田 俊介
• ▲高▼橋 明弘

Assignees

• 旭化成ワッカーシリコーン株式会社

Dates

Publication Date

20260507

Application Date

20250825

Priority Date

20241021

Claims (9)

1. (A) A diorganopolysiloxane containing an alkenyl group bonded to a silicon atom, (B) A diorganopolysiloxane having a hydrogen atom bonded to a silicon atom, (C) At least one thermally conductive filler selected from aluminum oxide (C1) with an average particle size of less than 5 μm and a hot water extracted sodium oxide content of less than 300 ppm, as quantified by atomic absorption spectrometry, and aluminum hydroxide (C2) with an average particle size of less than 5 μm and a hot water extracted sodium oxide content of less than 70 ppm, as quantified by atomic absorption spectrometry, wherein the first thermally conductive filler is present in an amount of 30 parts by mass or more and 220 parts by mass or less per 100 parts by mass of the total of components (A) and (B), (D) An aluminum hydroxide filler having an average particle size of 5 μm to 100 μm, wherein the sodium oxide content extracted with hot water is less than 70 ppm, as quantified by atomic absorption spectrometry, and comprising 400 parts by mass to 950 parts by mass of a second thermally conductive filler per 100 parts by mass of the total of components (A) and (B), (E) An addition catalyst in an amount of 0.2 parts by mass or more and 1.0 part by mass or less per 100 parts by mass of the total of component (A) and component (B), A thermally conductive silicone composition containing [a specific substance].
2. The thermally conductive silicone composition according to claim 1, wherein the ratio of component (A) to component (B) is in the range of SiH/SiVi, which is between 0.5 and 1.5.
3. The thermally conductive silicone composition according to claim 1, wherein component (A) comprises an organopolysiloxane having a viscosity of 10 mPa·s or more and 7,000 mPa·s or less at 25°C.
4. The thermally conductive silicone composition according to claim 1, wherein component (B) comprises an organopolysiloxane having two or more hydrogen atoms in one molecule and having a viscosity of 10 mPa·s or more and 7,000 mPa·s or less at 25°C.
5. The thermally conductive silicone composition according to claim 1, further comprising an adhesive condensation catalyst, wherein the adhesive condensation catalyst is an alkoxy compound containing Ti or Zr.
6. The thermally conductive silicone composition according to claim 1, wherein the thermal conductivity of the thermally conductive silicone composition or its cured product is 2.0 W/m·k or higher.
7. The thermally conductive silicone composition according to claim 1, wherein the reduction rate of the tensile shear adhesive stress of the cured product of the thermally conductive silicone composition is 30% or less.
8. The thermally conductive silicone composition according to claim 1, wherein the rate of decrease in hardness of the cured product of the thermally conductive silicone composition is 20% or less.
9. The aforementioned thermally conductive silicone composition, The thermal conductive silicone composition according to claim 1, comprising a first liquid and a second liquid packaged separately from each other, wherein the first liquid and the second liquid are mixed at the time of use to form a thermal conductive silicone composition.

Description

This disclosure relates to a thermally conductive silicone composition. Thermally conductive silicone compositions, such as gap fillers, are directly applied to heat-generating or heat-sinking elements, such as batteries in electric vehicles or semiconductors in electronic devices, and have the function of transferring the heat they generate to heat-dissipating components such as heat sinks. In recent years, with the spread of environmentally friendly electric vehicles, the development of high-performance batteries has progressed. Against this backdrop, many thermally conductive silicone products have been developed to transfer the heat generated by heat-generating elements such as electronic components and batteries to heat-dissipating components such as heat sinks. Furthermore, since automobiles require weight reduction, it is desirable that the components installed in automobiles have a low specific gravity. The thermally conductive silicone composition for gap fillers described in Patent Document 1 uses only aluminum hydroxide filler. However, since Patent Document 1 uses an alkoxy catalyst having Si bonds as a condensation catalyst, the adhesion is insufficient. Furthermore, Patent Document 2 discloses a silicone composition for gap fillers with improved adhesion. This silicone composition uses a Ti-Zr alkoxy compound as a condensation catalyst and an addition catalyst in combination. In gap filler applications, further weight reduction is desired while maintaining thermal conductivity and adhesion. Patent No. 6339761International Publication No. WO2023-053760 This figure shows the mixing ratio of the first and second liquids in the example.This figure shows the parts by mass of each component based on component A-1 of the first liquid in the example, and the parts by mass of each component based on the sum of A-1, A-2, and B-1 of the second liquid.This figure shows the mixing ratio of the example and the results for tensile shear bonding stress, hardness, and thermal conductivity.This figure shows the mass portion representation and the results of tensile shear bonding stress, hardness, and thermal conductivity for the example.This figure shows the mixing ratio of the first and second solutions in the comparative example.This figure shows the parts by mass of each component based on component A-1 of the first comparative solution, and the parts by mass of each component based on the sum of A-1, A-2, and B-1 of the second solution.This figure shows the mixing ratio of the comparative example and the results for tensile shear bonding stress, hardness, and thermal conductivity.This figure shows the mass portion representation and the results for tensile shear bonding stress, hardness, and thermal conductivity of the comparative example. The following describes the details of the thermally conductive silicone composition and the method for producing the thermally conductive silicone composition according to the present invention. (Thermally conductive silicone composition) The thermally conductive silicone composition can be any composition for forming a thermally conductive member. Examples of thermally conductive members include heat-generating elements such as car batteries, or substrates, circuit chips, and heat dissipation members for electrical or electronic equipment. The thermally conductive silicone composition may be applied to the substrate in a liquid state before curing, and then cured to provide a thermally conductive member, or the cured thermally conductive member may be applied to the substrate. The temperature and procedure for curing the thermally conductive silicone composition can be appropriately selected depending on the intended use of the resulting cured product, and are not limited to these factors. The curing method for thermally conductive silicone compositions is preferably an addition reaction type. The main reasons for this are that curing can be controlled over a wide temperature range from room temperature to approximately 150°C, there is little volume change or desorption of gases, and it generally has good compatibility with thermally conductive fillers. While generally higher curing temperatures result in faster curing, this invention assumes that, due to various constraints depending on the application, some or all of the steps involved—including the application of the thermally conductive silicone composition, curing, and subsequent steps—may be performed at room temperature. Therefore, an appropriate curing temperature can be set accordingly. Regarding the case where the curing method of the thermally conductive silicone composition according to the present invention is an addition reaction type, the components of the thermally conductive silicone composition will be described in detail below. [Component (A)] Component (A) is the main component of the thermally conductive silicone composition and is a diorganopolysiloxane containing alkenyl groups bonded to silicon a