US-20260125535-A1 - THERMALLY CONDUCTIVE CLAY COMPOSITION

Abstract

A thermally conductive clay composition contains a liquid polyol and an inorganic filler, in which the amount of the inorganic filler with respect to 100 parts by mass of the liquid polyol is within a range of 1,000 parts by mass or more and 3,300 parts by mass or less, and a tackiness index defined by an integral value of a region to which a tensile load is applied when a probe is pulled up in a tackiness tester is 10 g·s or greater.

Inventors

• Shintaro Iida
• Keiko ASHIDA

Assignees

• MITSUBISHI MATERIALS CORPORATION

Dates

Publication Date

20260507

Application Date

20240110

Priority Date

20230110

Claims (4)

1. 1 . A thermally conductive clay composition comprising: a liquid polyol; and an inorganic filler, wherein an amount of the inorganic filler with respect to 100 parts by mass of the liquid polyol is within a range of 1,000 parts by mass or more and 3,300 parts by mass or less, and a tackiness index defined by an integral value of a region to which a tensile load is applied when a probe is pulled up in a tackiness tester is 10 g s or greater.
2. 2 . The thermally conductive clay composition according to claim 1 , wherein the liquid polyol is one or more kinds selected from the group consisting of a polybutadiene polyol, a polyester polyol, a polyisoprene polyol, and a polyolefin polyol.
3. 3 . The thermally conductive clay composition according to claim 1 , wherein the inorganic filler is one or more kinds selected from the group consisting of aluminum oxide, aluminum nitride, boron nitride, silicon nitride, silicon carbide, magnesium oxide, and zinc oxide.
4. 4 . The thermally conductive clay composition according to claim 1 , wherein an average particle diameter of the inorganic filler is within a range of 0.1 μm or more and 200 μm or less.

Description

TECHNICAL FIELD This invention relates to, for example, a thermally conductive clay composition that is disposed between a heat generating body and a heat dissipation member and efficiently transfers heat generated from the heat generating body to the heat dissipation member. Priority is claimed on Japanese Patent Application No. 2023-001565, filed Jan. 10, 2023, and Japanese Patent Application No. 2023-205643, filed Dec. 5, 2023, the contents of which are incorporated herein by reference. BACKGROUND ART In recent years, as the performance and integration of various electronic devices have been improved, there is a demand for a structure in which heat radiation has been increased so that heat generated along with the operation of a constituent component (heat generating body) can be efficiently dissipated to the outside using a heat dissipation member. Thus, in order to reduce the thermal resistance between the heat generating body and the heat dissipation member, a heat transfer sheet may be disposed between the heat generating body and the heat dissipation member. For example, Patent Document 1 proposes a polyurethane resin composition in which heat radiation is improved by mixing inorganic substances such as a ceramic powder, a metal powder, and a carbon material with a polyurethane, which is a base material, and a thermally conductive sheet made from this polyurethane resin composition. Furthermore, Patent Document 2 proposes a fluorine-containing elastomer composition for a heat dissipation material, in which an insulating thermally conductive filler such as aluminum oxide is added to a fluorine-containing elastomer, which is a base material, to improve heat radiation, and a heat transfer sheet made from this fluorine-containing elastomer composition for a heat dissipation material. CITATION LIST Patent Documents Patent Document 1: Japanese Unexamined Patent Application, First Publication No. 2010-248350(A)Patent Document 2: Japanese Patent No. 6493616(B) SUMMARY OF INVENTION Technical Problem Incidentally, with regard to the polyurethane resin composition and the thermally conductive sheet described in Patent Document 1, a polyurethane is synthesized by a urethane curing reaction in which a polyol and an isocyanate are crosslinked by a urethane bond. Here, the isocyanate used in the urethane curing reaction is toxic and difficult to handle. Furthermore, with regard to a sheet produced by a curing reaction, there is a risk that the shape followability is poor, the adhesiveness to the heat generating body and the heat dissipation member cannot be ensured, and the thermal resistance between the heat generating body and the heat dissipation member cannot be sufficiently reduced in a case where there is surface unevenness in either the heat generating body or the heat dissipation member, or the like. Furthermore, the fluorine-containing elastomer composition for a heat dissipation material and the heat transfer sheet described in Patent Document 2 are flexible because they do not involve a curing reaction, and have excellent shape followability as compared with the thermally conductive sheet of Patent Document 1. However, the fluorine-containing elastomer is relatively expensive, and there is a problem that the production cost increases. Furthermore, the fluorine-containing elastomer has poor wettability with an inorganic substance, and there is a risk that voids may be generated inside the heat transfer sheet, which may result in a decrease in the thermal conduction properties. This invention has been made in view of the above-described circumstances, and an object of the invention is to provide a thermally conductive clay composition which is clay-like and has particularly excellent shape followability, and which sufficiently contains an inorganic filler and therefore has particularly excellent thermal conduction properties. Solution to Problem In order to solve the above-described problems, the inventors of the present invention conducted intensive studies, and as a result, they found that since liquid polyols have hydrophilic hydroxyl groups, liquid polyols have good wettability with inorganic fillers, and even when a large amount of the inorganic filler is contained, liquid polyols become clay-like, making it possible to ensure shape followability. Furthermore, the inventors found that shape followability can be ensured by evaluating the tackiness index using a tackiness tester. The present invention has been made based on the above-described findings, and a thermally conductive clay composition of Aspect 1 of the present invention contains a liquid polyol and an inorganic filler, in which the amount of the inorganic filler with respect to 100 parts by mass of the liquid polyol is within a range of 1,000 parts by mass or more and 3,300 parts by mass or less, and a tackiness index defined by an integral value of a region to which a tensile load is applied when a probe is pulled up in a tackiness tester