| 摘要 |
PROBLEM TO BE SOLVED: To widely set the latitude of electrification and breakdown voltage, to prevent pinholes, to suppress the blended quantity of conductive powder and to provide high mechanical strength by dispersing needle-like conductive powder having specific powder resistance and a specific aspect ratio in a surface resin layer, and adjusting the surface resistance of the surface resin layer within a specific range. SOLUTION: The needle-like conductive powder having the aspect ratio >=3, preferably in the range of 3-500, is used for a surface rein layer. When the aspect ratio is <3, an effective electric path cannot be formed by a small quantity of the conductive powder. When the aspect ratio exceeds 500, a pinhole leak easily occurs. The powder resistance of the needle-like conductive powder is set to 10<3> -10<6>Ωcm. When it is <10<3>Ωcm, the pinhole leak cannot be prevented sufficiently. When it is >=10<6>Ωcm, the necessary electric resistance cannot be applied to the surface resin layer, and defective electrification easily occurs. It is preferably set to 10<4> -10<6>Ωcm.
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