Semiconducting composition
View Patent ↗An improved conductor shielding composition for power cables is disclosed. The composition includes a base polymer, conductive carbon black, polyethylene glycol and a waxy additive. Cable shields prepared from the composition exhibit improved aging performance in accelerated cable life tests (ACLT).
1. A conductor shield composition comprising:
a base polymer selected from the group consisting of copolymers of ethylene and a mono-unsaturated ester, copolymers of ethylene and one or more alpha olefins having three to six carbon atoms, EPR rubbers, low density polyethylene and linear low density polyethylene;
conductive carbon black;
polyethylene glycol; and
about 0.5% to about 5.0% by weight of the composition of an ethylene vinyl acetate wax.
2. The composition of claim 1 , wherein said ethylene vinyl acetate wax has a molecular weight from about 5,000 Daltons to about 40,000 Daltons and a vinyl acetate content of from about 2% to about 28%.
3. The composition of claim 2 , wherein said at least one ethylene vinyl acetate wax has a vinyl acetate content of from about 8% to about 20%.
4. The composition of claim 2 , Wherein said at least one ethylene vinyl acetate wax has a molecular weight from about 10,000 Daltons to about 25,000 Daltons and a vinyl acetate content of from about 12% to about 15%.
5. The composition of claim 1 , wherein said base polymer is a copolymer of ethylene and vinyl acetate.
6. The composition of claim 5 , wherein said base polymer has a vinyl acetate content between about 2% and about 28%.
7. The composition of claim 1 , wherein the polyethylene glycol has a molecular weight of about 5000 to about 25,000 Daltons.
8. The composition of claim 1 having an accelerated cable life testing Weibull Alpha value of 1500 or more.