Thermally conductive silicone composition and thermally conductive silicone sheet

Patent metadata

Field	Value
Publication number	US-12404373-B2
Application number	US-202017775173-A
Country	US
Kind code	B2
Filing date	Oct 27, 2020
Priority date	Nov 14, 2019
Publication date	Sep 2, 2025
Grant date	Sep 2, 2025

Abstract

Provided is a thermally conductive silicone composition that can be turned into a lightweight cured product superior in thermal conductivity, and is easily processable due to its low viscosity. The composition contains:
(A) an organopolysiloxane having at least two alkenyl groups per each molecule; (B) an organohydrogenpolysiloxane having, per each molecule, at least two hydrogen atoms directly bonded to silicon atoms; (C) a thermally conductive filler containing magnesium oxide (20 to 40% by mass), aluminum oxide (40 to 60% by mass) and aluminum hydroxide (10 to 30% by mass); (D) a dimethylpolysiloxane with one end of the molecular chain thereof being blocked by a trialkoxy group; (E) a platinum group metal-based curing catalyst; and (F) an addition reaction control agent.

First claim

The invention claimed is:

1. A thermally conductive silicone composition comprising:
(A) 100 parts by mass of a linear organopolysiloxane having at least two alkenyl groups per each molecule and at least one of the at least two alkenyl groups is a vinyl group, and a kinetic viscosity of the linear organopolysiloxane at 25° C. is from 300 to 50,000 mm 2 /s;
(B) an organohydrogenpolysiloxane having, per each molecule, at least two hydrogen atoms directly bonded to silicon atoms, the component (B) being in an amount where the number of the hydrogen atoms directly bonded to the silicon atoms is 0.2 to 2.0 times larger than the number of the alkenyl groups in the component (A), wherein the organohydrogenpolysiloxane (B) is represented by the following general formula (3):

wherein R 7 independently represents a hydrogen atom, a substituted or unsubstituted alkyl group having 1 to 3 carbon atoms, or a substituted or unsubstituted phenyl group, and n is an integer of from 1 to 200;
(C) 2,600 to 4,680 parts by mass of a thermally conductive filler containing magnesium oxide, aluminum oxide and aluminum hydroxide;
(D) 140 to 250 parts by mass of a surface treatment agent of the thermally conductive filler, which is a dimethylpolysiloxane with one end of the molecular chain thereof being blocked by a trialkoxy group, as represented by the following general formula (1):

wherein R 5 independently represents an alkyl group having 1 to 6 carbon atoms, and c is an integer of 5 to 100;
(E) a platinum group metal-based curing catalyst in an amount of 0.1 to 1,000 ppm in terms of mass of platinum group metal elements with respect to the component (A); and
(F) an effective amount of an addition reaction control agent,
wherein the thermally conductive filler as the component (C) is such that the magnesium oxide is contained by an amount of 21 to 36% by mass per the total amount of the component (C), the aluminum oxide is contained by an amount of 40 to 56% by mass per the total amount of the component (C), and the aluminum hydroxide is contained by an amount of 12 to 28% by mass per the total amount of the component (C); and the magnesium oxide has an average particle size of 60 to 90 μm, the aluminum oxide has an average particle size of 1 to 70 μm, and the aluminum hydroxide has an average particle size of 8 to 50 μm.

2. The thermally conductive silicone composition according to claim 1 , wherein the thermally conductive silicone composition has a viscosity of 10 to 120 Pa·s.

3. The thermally conductive silicone composition according to claim 1 , wherein a cured product of the thermally conductive silicone composition has a density of not higher than 3.0 g/cm 3 and a thermal conductivity of not lower than 3.8 W/mK.

4. The thermally conductive silicone composition according to claim 1 , wherein a cured product of the thermally conductive silicone composition has an Asker C hardness of not higher than 60.

5. The thermally conductive silicone composition according to claim 1 , wherein in the general formula (1) of the surface treatment agent (D), c is an integer of about 30.

6. A thermally conductive silicone sheet that is a cured product of the thermally conductive silicone composition according to claim 1 .

Assignees

• Shinetsu Chemical Co

Inventors

• Tsukada Junichi
• Ito Takanori
• Endo Akihiro
• Miyano Megumi

Classifications

• C08K2201/005

  Additives being defined by their particle size in general · CPC title

• C08K2201/001

  Conductive additives · CPC title

• C08K2003/2227

  of aluminium · CPC title

• C08K2003/222

  Magnesia, i.e. magnesium oxide · CPC title

• C08K9/06

  with silicon-containing compounds · CPC title