Abstract: A manufacturing method of an electret processed product, comprising the steps of allowing a section nozzle (22) to come into contact with a nonconductive fiber sheet (S) so as to cross in the lateral direction of the sheet while running the sheet, allowing the surface of the sheet on the opposite side of the contact portion to come into contact with or to immerse into a water surface, sucking water from the suction nozzle (22) so that the water can be passed through the sheet in the thickness direction of the sheet to penetrate the water into the nonconductive fiber sheet (S), and drying the nonconductive fiber sheet (S), whereby a high quality and high performance electret processed product can be manufactured at a low cost.

Abstract: A manufacturing method of an electret processed product, comprising the steps of allowing a section nozzle (22) to come into contact with a nonconductive fiber sheet (S) so as to cross in the lateral direction of the sheet while running the sheet, allowing the surface of the sheet on the opposite side of the contact portion to come into contact with or to immerse into a water surface, sucking water from the suction nozzle (22) so that the water can be passed through the sheet in the thickness direction of the sheet to penetrate the water into the nonconductive fiber sheet (S), and drying the nonconductive fiber sheet (S), whereby a high quality and high performance electret processed product can be manufactured at a low cost.

Abstract: Nonwoven fabric for pleated filters comprising a sheath-core conjugate filament in which the core component is made of a polymer higher in melting point and the sheath component is made of a polymer lower in melting point, having compressively bonded portions dotted by embossing, with a weight per unit area X (g/m2) of the nonwoven fabric and a stiffness Y (mgf) obtained according to the Gurley method of JIS L 1096 of Y/X2≧0.03 and X≧120.