Semi-conductive compositions for wire and cable
AssigneeEquistar Chemicals, LP
InventorsChun D. Lee, James J. Pickering
Life of this patent
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Abstract
Semi-conductive compositions useful for extrusion coating wire and cable are provided. The semi-conductive extrusion coating compositions of the invention utilize a base resin containing linear low density polyethylene and a combination of a higher structure conductive carbon black and a lower structure conductive carbon black. The linear low density polyethylene may be combined with other polyolefin resins, such as low density polyethylene. The resulting semi-conductive compositions have a useful balance of processability and thermomechanical stability and physical/mechanical properties making make them particularly well-suited for use as conductive layers for power cable constructions.
Claims21
A semi-conductive extrusion composition having a complex viscosity at 210° C. and 100 rad/sec from 6000 to 25000 poise and dispersion number from 50 to 700 psi comprising:
- (a) 75 to 95 weight percent, based on the total weight of the composition, of a base resin comprising linear low density polyethylene having a density from 0.890 to 0.925 g/cm3 and melt index from 0.3 to 15 g/10 min and (b) 5 to 25 weight percent, based on the total weight of the composition, of a carbon black mixture containing a major portion of a higher structure conductive carbon black and a minor proportion of a lower structure conductive carbon black.
A semi-conductive extrusion composition having a complex viscosity of 8000 to 15000 and dispersion number from 50 to 500 psi comprising (a) 75 to 95 weight percent, based on the total weight of the composition, of a base resin having a density of 0.905 to 0.922 g/cm3 and melt index from 0.5 to 7.5 g/10 min comprising 70 to 95 weight percent, based on the weight of the base resin, linear low density polyethylene copolymer and 5 to 30 weight percent, based on the weight of the base resin, low density polyethylene homopolymer and (b) 7 to 18 weight percent based on the total weight of the composition of a carbon black mixture comprised essentially of (I) 51 to 85 weight percent, based on the total weight of the carbon black mixture, of a higher structure conductive black having a particle size of 10 to 50 nm BET surface area greater than 500 m2/g, dibutyl phthalate absorption number from 200 to 600 ml/100 g and volatiles content less than 2 percent and 15 to 49 weight percent, based on the total weight of the carbon black mixture, of a lower structure carbon black having a particle size of 10 to 50 nm, BET surface area of 125 to 500 m2/g, dibutyl phthalate absorption number of 80 to 250 ml/100 g and volatiles content of 2 percent or below.
Dependencies are inferred from the claim text.