High thermal conductivity materials with grafted surface functional groups
View Patent ↗The present invention is a continuous high thermal conductivity resin featuring high thermal conductivity (HTC) materials 30 and a host resin matrix 32 . The HTC materials 30 form a continuous organic-inorganic composite with the host resin matrix 32 via surface functional groups that are grafted to the HTC materials 30 and form covalent linkages with the host resin matrix 32 . Phonons 34 tend to pass along the HTC materials 30 as they travel through the host resin matrix 32 , and phonons 36 pass to the next HTC material if the distance between these materials is less than n.
1. A continuous high thermal conductivity resin comprising:
a host resin matrix; and
a plurality of nanosized high thermal conductivity fillers consisting essentially of fillers having a length of from about 1-1000 nm;
wherein said plurality of nanosized high thermal conductivity fillers form a continuous organic-inorganic composite with said host resin matrix via surface functional groups that are grafted to said plurality of nanosized high thermal conductivity fillers and form covalent linkages with said host resin matrix;
wherein said continuous organic-inorganic composite is effective to reduce phonon scattering and increase phonon transport in the continuous high thermal conductivity resin while at least maintaining dielectric strength and voltage endurance of the continuous high thermal conductivity resin;
wherein the continuous high thermal conductivity resin has a viscosity that renders the continuous high thermal conductivity resin suitable for impregnation by vacuum-pressure impregnation (VPI) or global vacuum-pressure impregnation (GVPI);
wherein said host resin matrix comprises an epoxy resin;
wherein said surface functional groups grafted to said plurality of nanosized high thermal conductivity fillers comprise epoxide groups; and
wherein said epoxide groups grafted to said plurality of nanosized high thermal conductivity fillers react directly with the epoxy resin to form said continuous organic-inorganic composite.
2. The resin of claim 1 , wherein said plurality of nanosized high thermal conductivity fillers are chosen from at least one of oxides, nitrides, carbides or diamond.
3. The resin of claim 1 , wherein said plurality of nanosized high thermal conductivity fillers have an aspect ratio of between 3-100.
4. The resin of claim 3 , wherein said plurality of nanosized high thermal conductivity fillers have an aspect ratio of between 10-50.
5. An impregnated porous media comprising an insulating paper impregnated with the continuous high thermal conductivity resin of claim 1 , wherein the impregnated resin comprises minimal to no voids formed therein.
6. The resin of claim 1 , wherein said surface functional groups further comprise at least one of hydroxyl, carboxylic, amine, silane or vinyl groups.
7. The continuous high thermal conductivity resin of claim 1 , wherein at least 75% of said plurality of nanosized high thermal conductivity fillers comprise a filler having a mean path length between itself and an adjacent second filler that is less than a phonon mean free path of the host resin matrix.
8. The continuous high thermal conductivity resin of claim 1 , wherein said continuous organic-inorganic composite comprises a maximum of 35% by volume of the nanosized high thermal conductivity fillers.
9. The continuous high thermal conductivity resin of claim 1 , wherein said functional groups are chemically and directly grafted to said plurality of nanosized high thermal conductivity fillers.