Thermally conductive silicone grease composition and method for producing the same
A non-curable thermally conductive silicone grease composition includes: A. 100 parts by mass of a non-curable silicone oil with a kinematic viscosity of 50 to 10000 mm 2 /s at 40° C.; and B. 105 to 500 parts by mass of thermally conductive particles with respect to 100 parts by mass of the component A. The thermally conductive particles contain the following: B1. 50 to 300 parts by mass of irregularly-shaped alumina with a median particle size of 0.1 to 1 μm, in which a part or all of the alumina is surface treated; B2. 5 to 50 parts by mass of plate-like boron nitride with a median particle size of 0.1 to 10 μm; and B3. 50 to 150 parts by mass of aggregated boron nitride with a median particle size of 20 to 70 μm. The B 3 /B 2 blending ratio is 2 to 20. Thus, the thermally conductive silicone grease composition has a high thermal conductivity, but still has a relatively low specific gravity, and also has a viscosity for good workability and good coating properties.
1 . A thermally conductive silicone grease composition that is non-curable, comprising:
A. 100 parts by mass of a non-curable silicone oil with a kinematic viscosity of 50 to 10000 mm 2 /s at 40° C.; and
B. 105 to 500 parts by mass of thermally conductive particles with respect to 100 parts by mass of the component A,
wherein the thermally conductive particles contain the following:
B1. 50 to 300 parts by mass of pretreated irregularly-shaped alumina with a median particle size of 0.1 to 1 μm, in which a part or all of the alumina previously was surface treated, before mixing of the irregularly-shaped alumina with the silicone oil, with an alkoxysilane compound expressed by R a Si(OR′) 4-a , where R represents a substituted or unsubstituted alkyl group having 8 to 12 carbon atoms, R′ represents an alkyl group having 1 to 4 carbon atoms, and a represents 0 or 1, or a partial hydrolysate of the alkoxysilane compound;
B2. 5 to 50 parts by mass of plate-like boron nitride with a median particle size of 0.1 to 1 μm; and
B3. 50 to 150 parts by mass of aggregated boron nitride with a median particle size of 20 to 70 μm,
wherein a blending ratio of the component B3 to the component B2 is 2 to 20,
wherein the thermally conductive silicone grease composition has a specific gravity of 1.0 or more and 2.0 or less and a thermal conductivity of 2.0 W/m·K or more and 8.0 W/m·K or less, and an absolute viscosity of 1000 to 7000 Pas at 23° C., as measured with a B-type viscometer using a T-E spindle at a rotational speed of 5 rpm.
2 . The thermally conductive silicone grease composition according to claim 1 , further comprising 0.1 to 2 parts by mass of an alkoxysilane compound expressed by R a Si(OR′) 4-a , where R represents a substituted or unsubstituted alkyl group having 8 to 12 carbon atoms, R′ represents an alkyl group having 1 to 4 carbon atoms, and a represents 0 or 1, as a component C in addition to the component A and the component B.
3 . The thermally conductive silicone grease composition according to claim 1 , wherein 0.01 to 10 parts by mass of the alkoxysilane compound was added to 100 parts by mass of the irregularly-shaped alumina of the component B1 before mixing of the irregularly-shaped alumina of the component B1 with the silicone oil.
4 . The thermally conductive silicone grease composition according to claim 1 , wherein the thermally conductive silicone grease composition is put into at least one selected from the group consisting of a dispenser, a bottle, a can, and a tube.
5 . A method for producing a non-curable thermally conductive silicone grease composition, the method comprising:
mixing 105 to 500 parts by mass of thermally conductive particles (B) with 100 parts by mass of a non-curable silicone oil (A) with a kinematic viscosity of 50 to 10000 mm 2 /s at 40° C.,
wherein the thermally conductive particles contain the following:
B1. 50 to 300 parts by mass of pretreated irregularly-shaped alumina with a median particle size of 0.1 to 1 μm, in which a part or all of the alumina previously was surface treated, before mixing of the irregularly-shaped alumina with the silicone oil, with an alkoxysilane compound expressed by R a Si(OR′) 4-a , where R represents a substituted or unsubstituted alkyl group having 8 to 12 carbon atoms, R′ represents an alkyl group having 1 to 4 carbon atoms, and a represents 0 or 1, or a partial hydrolysate of the alkoxysilane compound;
B2. 5 to 50 parts by mass of plate-like boron nitride with a median particle size of 0.1 to 10 μm; and
B3. 50 to 150 parts by mass of aggregated boron nitride with a median particle size of 20 to 70 μm,
wherein a blending ratio of the component B3 to the component B2 is 2 to 20,
wherein the produced thermally conductive silicone grease composition has a specific gravity of 1.0 or more and 2.0 or less and a thermal conductivity of 2.0 W/m·K or more and 8.0 W/m·K or less, and an absolute viscosity of 1000 to 7000 Pas at 23° C., as measured with a B-type viscometer using a T-E spindle at a rotational speed of 5 rpm.
6 . The method according to claim 5 , wherein the thermally conductive silicone grease composition further comprises 0.1 to 2 parts by mass of an alkoxysilane compound expressed by R a Si(OR′) 4-a , where R represents a substituted or unsubstituted alkyl group having 8 to 12 carbon atoms, R′ represents an alkyl group having 1 to 4 carbon atoms, and a represents 0 or 1, as a component C in addition to the component A and the component B.
7 . The method according to claim 5 , wherein 0.01 to 10 parts by mass of the alkoxysilane compound was added to 100 parts by mass of the irregularly-shaped alumina of the component B1 before mixing of the irregularly-shaped alumina of the component B1 with the silicone oil.
8 . The method according to claim 5 , wherein the thermally conductive silicone grease composition is put into at least one selected from the group consisting of a dispenser, a bottle, a can, and a tube.