Abstract: The present invention relates to a fiber assembly obtained by electrifying a resin in a melted state by application of voltage between a supply-side electrode and a collection-side electrode so as to extend the resin into an ultrafine composite fiber by electrospinning, and accumulating the ultrafine composite fiber, wherein the ultrafine composite fiber includes at least two polymeric components and the ultrafine composite fiber includes at least one type of composite fiber selected from a sea-island structure composite fiber and a core-sheath structure composite fiber as viewed in fiber cross section, at least one selected from an island component and a core component has a volume specific resistance of 1015?·cm or less, and at least one selected from a sea component and a sheath component has a volume specific resistance exceeding 1015?·cm.

Abstract: The present invention relates to a fiber assembly obtained by electrifying a resin in a melted state by application of voltage between a supply-side electrode and a collection-side electrode so as to extend the resin into an ultrafine composite fiber by electrospinning, and accumulating the ultrafine composite fiber, wherein the ultrafine composite fiber includes at least two polymeric components and the ultrafine composite fiber includes at least one type of composite fiber selected from a sea-island structure composite fiber and a core-sheath structure composite fiber as viewed in fiber cross section, at least one selected from an island component and a core component has a volume specific resistance of 1015?·cm or less, and at least one selected from a sea component and a sheath component has a volume specific resistance exceeding 1015?·cm.

Abstract: An ultrafine composite fiber of the present invention is obtained by heating and melting a composite-resin-formed product in front of a supply-side electrode and/or in a space between electrodes and extending the composite-resin-formed product by electrospinning, wherein the composite-resin-formed product is a solid-state composite-resin-formed product having two or more phases and including a resin that has a volume specific resistance of 1015 ?·cm or less, and that is exposed on 30% or more of a surface of the composite-resin-formed product. With this, an ultrafine composite synthetic fiber and an ultrafine synthetic fiber can be obtained by electrospinning, without a solvent being mixed in a supply resin, and further, a method for manufacturing an ultrafine composite fiber, as well as a fiber structure containing an ultrafine composite fiber, are provided.

Abstract: An organic electrolyte battery separator is composed of a nonwoven comprising a heat-and-humidity gelling resin capable of gelling by heating in the presence of moisture and another fiber. The other fiber is fixed with a gel material obtained by causing the heat-and-humidity gelling resin to gel under heat and humidity. The nonwoven has a mean flow pore diameter of 0.3 ?m to 5 ?m and a bubble point pore diameter of 3 ?m to 20 ?m as measured in accordance with ASTM F 316 86. Thereby, the other fiber constituting the nonwoven can be fixed with the heat-and-humidity gelling resin, thereby making it possible to obtain a desired mean flow pore diameter and bubble point pore diameter. As a result, an organic electrolyte battery having a high level of safety, less occurrence of a short circuit, high battery characteristics is provided.

Abstract: A separator material of the present invention is a sulfonated nonwoven that comprises a polyolefin ultra-fine short fiber having a fineness of less than 0.5 dtex and other polyolefin short fiber(s). The other polyolefin short fibers include a polyolefin thermal bonding short fiber. At least a portion of the polyolefin thermal bonding short fiber is flattened to bond the component fibers together. The nonwoven has a specific surface area in a range of 0.6 m2/g to 1.5 m2/g and satisfies the following ranges. (1) A ratio (S/C)E of the number of sulfur atoms (S) to the number of carbon atoms (C) in the nonwoven, as measured by Electron Spectroscopy for Chemical Analysis (ESCA), is in a range of 5×10?3 to 60×10?3. (2) A ratio (S/C)B of the number of sulfur atoms (S) to the number of carbon atoms (C) in the nonwoven, as measured by a flask combustion technique, is in a range of 2.5×10?3 to 7×10?3. (3) A ratio (S/C)E/(S/C)B (depth of sulfonation) of (S/C)E to (S/C)B is in a range of 1.5 to 12.