| 摘要 |
PURPOSE:To obtain a high holding electric charge and its long-standing stability, by employing polyaromatic sulfide having a surface electric charge density of at least 5X10<-11> coulomb/cm<2> as a constituent material for an electret sheet- like matter. CONSTITUTION:Polyaromatic sulfide having a surface electric charge density higher at least than 5X10<-11> coulomb/cm<2> is used as a constituent material for an electret sheet-like matter. Polyaromatic sulfide is a polymer composed of -R-S(R: phenylene, biphenylene, naphthalene, biphenylene ether, diphenyl ketone) as a recurring unit. The shape of the sheet-like matter is film, woven fabric, unwoven cloth etc. Since polyaromatic sulfide, after being formed, crystalizes rapidly and shrinks by heating it at least to its glass transition temperature, the sheet-like matter is heat treated preferably at 85 deg.C or higher under suitable tension. |
