| 摘要 |
PROBLEM TO BE SOLVED: To improve the dispersibility of an additive and improve a DC characteristic by forming an insulating layer with the bridged polyethylene mixed with the polyethylene containing the molecular weight having little dispersion and a standard deviation within a specific range and the conductive additive at a specific ratio. SOLUTION: The molecular weight of straight chain low-density polyethylene has a standard deviation of 800-1200 and little dispersion, and it contains few molecules having a low molecular weight. The dispersibility between the straight chain molecules of a conductive additive adsorbing various ionic impurities is improved, and the accumulation of space charges is suppressed. When the conductive additive such as furnace carbon black or magnesium oxide of 0.1-0.8 pts.wt. is added to the polyethylene of 100 pts.wt., the required adding effect, impulse breakdown voltage, and volume resistivity can be obtained. The average grain size is preferably set to 0.01-0.1μm. When the melt flow index and density of the polyethylene are set to the prescribed ranges, the extrusion molding property and electric characteristics are improved.
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