Curable silicone compositions, methods and articles made therefrom

A silicone composition comprising a curable adhesive formulation which comprises

• (A) a polydiorganosiloxane having the general formula:
• (R1)3-p(R2)pSiO[(R1)2SiO]m[R1R2SiO]nSi(R1)3-qR2q
• wherein R2 is an acryloxy-functional group, R1 is a methyl group, “p” is 0 or 1, “q” is 0 or 1, “m”+“n” has a value sufficient to provide a polydiorganosiloxane with an initial viscosity in a range of between about 100 centipoise and about 50,000 centipoise at 25° C.;
• (B) at least one thermally conductive filler comprising silver present in a concentration in a range of between about 60% by weight and about 95% by weight, based on the total weight of the silicone composition;
• (C) at least one reactive diluant comprising methacryloxypropyltrimethoxysilane;
• (D) at least one curing catalyst comprising bisaryliodonium salt;
• and
• (E) optionally, at least one adhesion promoter comprising a bis(trimethoxysilylpropyl)fumarate;
• wherein the total silicone composition has a viscosity in a range of between about 10,000 centipoise and about 250,000 centipoise at 25° C. before cure and a thermal conductivity greater than about 1.5 W/mK after cure.

A method for substantially increasing the thermal conductivity of a silicone composition comprising:

• providing at least one functionalized polydiorganosiloxane wherein the polydiorganosiloxane has the general formula:
• (R1)3-pR2pSiO((R1)2SiO)m(R1R2SiO)nSi(R1)3-qR2q
• wherein R2 is independently, at each occurrence, a vinylcyclohexeneoxy functional group, a silane-functional group, an epoxy-functional group, a glycidoxy-functional group, an acryloxy-functional group, a polyimide-functional group, a polyurethane-functional group, vinyl or combinations thereof;
• R1 is independently, at each occurrence, a C1-8 alkyl radical, a phenyl radical, a vinyl radical or combinations thereof;
• “p” is 0 or 1;
• “q” is 0 or 1;
• “m”+“n” has a value sufficient to provide a polydiorganosiloxane with an initial viscosity in a range of between about 100 centipoise and about 50,000 centipoise at 25° C.;
• combining into the polydiorganosiloxane at least one thermally conductive filler in a range of between about 60% by weight and about 95% by weight of the total silicone composition;
• combining into the polydiorganosiloxane at least one reactive diluant present in a concentration at least about equal to the concentration of the polydiorganosiloxane;
• and
• combining into the polydiorganosiloxane at least one cure catalyst wherein the total silicone composition has a viscosity in a range of between about 10,000 centipoise and about 25,000 centipoise at 25° C. before cure and a thermal conductivity greater than about 1.5 W/mK after cure.

A method for increasing the thermal conductivity of a silicone composition comprising:

• providing at least one polydiorganosiloxane having the general formula:
• (R1)3-p(R2)pSiO((R1)2SiO)m(R1R2SiO)nSi(R1)3-qR2q
• wherein R2 is an acryloxy-functional group, R1 is a methyl group, “p” is 0 or 1, “q” is 0 or 1, “m”+“n” has a value sufficient to provide a polydiorganosiloxane with an initial viscosity in a range of between about 100 centipoise and about 50,000 centipoise at 25° C.;
• combining into the polydiorganosiloxane at least one thermally conductive filler in a range of between about 60% by weight and about 95% by weight of the total silicone composition wherein the filler comprises silver;
• combining into the polydiorganosiloxane at least one diluant wherein the diluant comprises methacryloxypropyltrimethoxysilane;
• combining into the polydiorganosiloxane at least one cure catalyst wherein the cure catalyst comprises a bisaryliodonium salt;
• and
• optionally combining into the polydiorganosiloxane at least one adhesion promoter comprising bis(trimethoxysilylpropyl)fumarate
• wherein the total silicone composition provides a viscosity in a range between about 10,000 centipoise and about 250,000 centipose at 25° C. before cure and the cured composition provides a thermal conductivity greater than about 1.5 W/mK.

A thermal interface material comprising:

• (A) at least one polydiorganosiloxane having the general formula:
• (R1)3-p(R2)pSiO((R1)2SiO)m(R1R2SiO)nSi(R1)3-qR2q
• wherein R2 is independently, at each occurrence, a vinylcyclohexeneoxy-functional group, a silane-functional group, an epoxy-functional group, a glycidoxy-functional group, an acryloxy-functional group, a polyimide-functional group, a polyurethane-functional group, vinyl or combinations thereof;
• R1 is independently, at each occurrence, a C1-8 alkyl radical, a phenyl radical, a vinyl radical or combinations thereof;
• “p” is 0 or 1;
• “q” is 0 or 1;
• “m”+“n” has a value sufficient to provide a polydiorganosiloxane with an initial viscosity in a range of between about 100 centipoise and about 50,000 centipoise at 25° C.;
• (B) at least one reactive diluant present in a concentration at least about equal to the concentration of component (A);
• (C) at least one cure catalyst;
• and
• (D) at least one thermally conductive filler present in a range of between about 60% by weight and about 95% by weight of the total silicone composition;
• wherein the thermal interface material provides adhesion to at least one substrate and has a thermal conductivity greater than about 1.5 W/mK.

A thermal interface material comprising:

• (A) at least one polydiorganosiloxane having the general formula:
• (R1)3-p(R2)pSiO[(R1)2SiO]m[R1R2SiO]nSi(R1)3-qR2q
• wherein R2 is an acryloxy-functional group, R1 is a methyl group, “p” is 0 or 1, “q” is 0 or 1, “m”+“n” has a value sufficient to provide a polydiorganosiloxane with an initial viscosity in a range of between about 100 centipoise and about 50,000 centipoise at 25° C.;
• (B) at least one thermally conductive filler comprising silver present in a concentration in a range of between about 60% by weight and about 95% by weight, based on the total weight of the silicone composition;
• (C) at least one reactive diluant comprising methacryloxypropyltrimethoxysilane present in a concentration at least about equal to the concentration of component (A);
• (D) at least one cure catalyst wherein the cure catalyst comprises a bisaryliodonium salt;
• and
• (E) optionally, at least one adhesion promoter comprising bis(trimethoxysilylpropyl)fumarate
• wherein the thermal interface material has a viscosity in a range of between about 10,000 centipoise and about 250,000 centipoise before curing and a thermal conductivity greater than about 1.5 W/mK following curing.