Thermally conductive silicone composition and cured product thereof

Patent metadata

Field	Value
Publication number	US-10647830-B2
Application number	US-201716303056-A
Country	US
Kind code	B2
Filing date	Apr 26, 2017
Priority date	May 24, 2016
Publication date	May 12, 2020
Grant date	May 12, 2020

Abstract

A thermally conductive silicone composition having an organopolysiloxane as a base polymer and containing a thermally conductive filler, wherein the thermally conductive silicone composition that includes aluminum nitride having an average particle size of 10-100 μm and crushed alumina having an average particle size of 0.1-5 μm as a thermally conductive filler, contains 15-55 mass % of crushed alumina in the total amount of aluminum nitride and crushed alumina, and contains a total of 60-95 mass % of aluminum nitride and crushed alumina in the thermally conductive silicone composition has excellent moldability, high thermal conductivity and low thermal resistance, can give a cured product also having excellent water resistance, and has good adhesiveness during mounting when used as a heat-dissipating member.

First claim

The invention claimed is:

1. A thermally conductive silicone composition comprising an organopolysiloxane as a base polymer and a thermally conductive filler, wherein the thermally conductive filler includes aluminum nitride having an average particle size of 10 to 100 μm and crushed alumina having an average particle size of 0.1 to 5 μm, the crushed alumina accounting for 15 to 55 wt % of the collective amount of aluminum nitride and crushed alumina, and the aluminum nitride and crushed alumina collectively accounting for 60 to 95 wt % of the thermally conductive silicone composition.

2. The thermally conductive silicone composition of claim 1 , comprising:
(A-1) 100 parts by weight of an organopolysiloxane containing at least two silicon-bonded alkenyl groups on the molecule and having a kinematic viscosity at 25° C. of from 10 to 100,000 mm 2 /s;
(B) from 1,000 to 4,000 parts by weight of, as the thermally conductive filler, aluminum nitride having an average particle size of 10 to 100 μm and crushed alumina having an average particle size of 0.1 to 5 μm;
(C-1) an organohydrogenpolysiloxane having at least two hydrogen atoms directly bonded to silicon atoms, in an amount such that the number of moles of hydrogen atoms directly bonded to silicon atoms is from 0.1 to 8 moles per mole of alkenyl groups from component (A-1); and
(D) from 0.1 to 2,000 ppm of a platinum family metal-based curing catalyst, expressed as the weight of the platinum family metallic element with respect to component (A-1), wherein the crushed alumina in component (B) is included in a proportion of at least 15 wt % and not more than 55 wt % of the total weight of component (B).

3. The thermally conductive silicone composition of claim 1 , comprising:
(A-2) 100 parts by weight of an organopolysiloxane of general formula (1) below

(wherein the R 1 groups are mutually like or unlike unsubstituted, halogen-substituted or cyano-substituted alkyl groups of 1 to 5 carbon atoms or aryl groups of 6 to 8 carbon atoms; and the subscript “a” is a number that sets the kinematic viscosity at 25° C. of the organopolysiloxane of formula (1) to the below-indicated value) which is capped at both ends with hydroxyl groups and has a kinematic viscosity at 25° C. of from 10 to 100,000 mm 2 /s;
(B) from 1,000 to 4,000 parts by weight of, as the thermally conductive filler, aluminum nitride having an average particle size of 10 to 100 μm and crushed alumina having an average particle size of 0.1 to 5 μm;
(C-2) from 1 to 40 parts by weight of one or more selected from the group consisting of silane compounds of general formula (2) below
R 2 b —SiX (4-b)   (2)

(wherein R 2 is an unsubstituted, halogen-substituted or cyano-substituted alkyl group of 1 to 3 carbon atoms, vinyl group or phenyl group; X is a hydrolyzable group; and the subscript b is 0 or 1), (partial) hydrolyzates thereof and (partial) hydrolytic condensates thereof; and
(F) from 0.01 to 20 parts by weight of a curing catalyst for a condensation reaction selected from the group consisting of alkyltin ester compounds, titanic acid esters, titanium chelate compounds, organozinc compounds, organoiron compounds, organocobalt compounds, organomanganese compounds, organoaluminum compounds, hexylamine, dodecylamine phosphate, quaternary ammonium salts, lower fatty acid salts of alkali metals, dialkylhydroxylamines and guanidyl group-containing silanes and siloxanes,

wherein the crushed alumina in component (B) is included in a proportion of at least 15 wt % and not more than 55 wt % of the total weight of component (B).

4. The thermally conductive silicone composition of claim 1 , comprising:
(A-3) 100 parts by weight of an organopolysiloxane containing at least two silicon-bonded alkenyl groups on the molecule and having a kinematic viscosity at 25° C. of from 10 to 100,000 mm 2 /s;
(B) from 1,000 to 4,000 parts by weight of, as the thermally conductive filler, aluminum nitride having an average particle size of 10 to 100 μm and crushed alumina having an average particle size of 0.1 to 5 μm; and
(G) from 0.01 to 10 parts by weight of an organic peroxide, wherein the crushed alumina in component (B) is included in a proportion of at least 15 wt % and not more than 55 wt % of the total weight of component (B).

5. The thermally conductive silicone composition of claim 1 , wherein the aluminum nitride in the thermally conductive filler is crushed and/or spherical.

6. The thermally conductive silicone composition of claim 5 , wherein crushed aluminum nitride having an average particle size of 10 to 100 μm in the thermally conductive filler is included in a proportion of at least 10 wt % and not more than 50 wt % of the total weight of the thermally conductive filler.

7. The thermally conductive silicone composition of claim 2 which further comprises, as component (H), from 10 to 200 parts by weight per 100 parts by weight of component (A-1), (A-2) or (A-3) of at least one selected from the group consisting of:
(H-1) alkoxy silane compounds of general formula (3) below
R 3 c R 4 d Si(OR 5 ) 4-c-d   (3)

(wherein R 3 is independently an alkyl group of 6 to 15 carbon atoms, R 4 is independently a substituted or unsubstituted monovalent hydrocarbon group of 1 to 8 carbon atoms, R 5 is independently an alkyl group of 1 to 6 carbon atoms, the subscript c is an integer from 1 to 3, the subscript d is 0, 1 or 2, and the sum c+d is an integer from 1 to 3); and
(H-2) dimethylpolysiloxanes of general formula (4) below

(wherein R 6 is independently an alkyl group of 1 to 6 carbon atoms, and the subscript e is an integer from 5 to 100) which are capped at one end of the molecular chain with a trialkoxysilyl group.

8. The thermally conductive silicone composition of claim 2 which further comprises:
(I) from 1 to 40 parts by weight, per 100 parts by weight of component (A-1), (A-2) or (A-3), of an organopolysiloxane of general formula (5) below
R 7 3 SiO—(R 7 2 SiO) f —SiR 7 3   (5)

(wherein R 7 is independently a monovalent hydrocarbon group of 1 to 8 carbon atoms without aliphatic unsaturated bonds, and the subscript f is an integer from 5 to 2,000) having a kinematic viscosity at 25° C. of from 10 to 100,000 mm 2 /s.

9. A cured product of the thermally conductive silicone composition of claim 1 , which cured product has a thermal conductivity of at least 5 W/mK.

Assignees

• Shinetsu Chemical Co

Inventors

• Ito Takanori

Classifications

• C08K3/22 Primary

  of metals · CPC title

• C08L83/06

  containing silicon bound to oxygen-containing groups (C08L83/12 takes precedence) · CPC title

• C08K2201/001

  Conductive additives · CPC title

• C08G77/12

  containing silicon bound to hydrogen · CPC title

• C08L83/14

  in which at least two but not all the silicon atoms are connected by linkages other than oxygen atoms (C08L83/10 takes precedence) · CPC title