THERMALLY CONDUCTIVE COMPOSITIONS AND CABLES THEREOF
A thermoset composition can include a cross-linked polyolefin; a primary filler selected from the group consisting of talc, calcined clay, or combinations thereof; a secondary filler selected from one or more of a metal oxide and a metal nitride, and one of a composition stabilizer and antioxidant. The thermoset composition can exhibit a thermal conductivity of at least about 0.27 W/mK, and/or a dielectric loss tangent of less than about 3% when measured at 90° C. The thermoset composition can be used in the construction on an insulation layer or jacket layer of a power cable.
1 . A thermoset composition comprising:
about 100 parts, by weight of the thermoset composition, of a cross-linked polyolefin;
from about 80 parts to about 160 parts, by weight of the thermoset composition, of a primary filler, the primary filler selected from the group consisting of talc, calcined clay, and combinations thereof;
a secondary filler comprising one or more of a metal oxide and a metal nitride; and
from about 0.5 part to about 10 parts, by weight of the thermoset composition, of at least one of a composition stabilizer and an antioxidant; and
wherein the thermoset composition exhibits a thermal conductivity of about 0.27 W/mK or greater, a dielectric loss tangent of about 3% or less when measured at about 90° C. after water aging at about 90° C. for about eight weeks, or both.
2 . The thermoset composition of claim 1 exhibits a thermal conductivity of about 0.30 W/mK or greater.
3 . The thermoset composition of claim 1 wherein the weight of the secondary filler is about 50% or less of the total weight of the primary filler and the secondary filler.
4 . The thermoset composition of claim 1 , wherein the secondary filler is selected from the group consisting of zinc oxide, magnesium oxide, aluminum oxide, silicon dioxide, boron nitride, aluminum nitride, and combinations thereof.
5 . The thermoset composition of claim 1 further comprising from about 0.5 parts to about 5 parts, by weight of the thermoset composition, of a surface treatment agent.
6 . The thermoset composition of claim 1 further comprising about 5 parts or less, by weight of the thermoset composition, of a processing oil.
7 . The thermoset composition of claim 1 , wherein the composition stabilizer comprises at least one of a UV stabilizer, a heat stabilizer, a lead stabilizer and a metal deactivator.
8 . The thermoset composition of claim 1 is substantially lead-free.
9 . The thermoset composition of claim 1 , wherein the cross-linked polyolefin comprises one or more of an ethylene-butene copolymer, ethylene-propylene-diene terpolymer, ethylene-octene copolymer, ethylene-propylene rubber, and a polyethylene.
10 . The thermoset composition of claim 1 , wherein about 80% or more of the said fillers have an average particle size about 20 microns or less.
11 . The thermoset composition of claim 1 has an elongation at break of about 200% or more.
12 . The thermoset composition of claim 1 has a break down strength of about 500 V/mil or more.
13 . The thermoset composition of claim 1 has a Mooney viscosity of about 30 ML or less at about 150° C.
14 . The thermoset composition of claim 1 has a dielectric constant of about 3.5 or less when measured at about 90° C.
15 . The thermoset composition of claim 1 has a dielectric loss tangent of about 2.5% or less when measured at about 90° C.
16 . A cable comprising an insulation layer and optionally a jacket layer, wherein one or more of the insulation layer and the jacket layer is formed from the thermoset composition of claim 1 .
17 . A cable comprising:
a conductor;
an insulation layer surrounding the conductor, the insulation layer formed from a thermoset composition, the thermoset composition comprising:
about 100 parts, by weight of the thermoset composition, of a cross-linked polyolefin;
from about 80 parts to about 160 parts, by weight of the thermoset composition, of a primary filler, the primary filler selected from the group consisting of talc, calcined clay, and combinations thereof;
a secondary filler comprising one or more of a metal oxide and a metal nitride; and
from about 0.5 part to about 10 parts, by weight of the thermoset composition, of at least one of a composition stabilizer and an antioxidant; and
wherein the thermoset composition exhibits a thermal conductivity of about 0.27 W/mK or greater, a dielectric loss tangent of about 3% or less when measured at about 90° C. after water aging at about 90° C. for about eight weeks, or both.
18 . The cable of claim 17 , further comprising a jacket layer surrounding the insulation layer.
19 . The cable of claim 17 , wherein the conductor has an operating temperature of about 5° C. or less relative to a comparative cable having a similar conductor but a different insulation layer.
20 . The cable of claim 17 , wherein the conductor has an operating temperature of about 5° C. or less relative to a similar conductor in a different cable having a different insulation layer, wherein the different insulation exhibits a thermal conductivity of about 0.27 W/mK or greater, a dielectric loss tangent of about 3% or less when measured at about 90° C. after water aging at about 90° C. for about eight weeks, or both.