Abstract: A method of producing a precursor fiber for carbon fiber includes extruding a polyacrylonitrile copolymer solution from a spinneret into the air, immersing it in a coagulation bath liquid stored in a coagulation bath, redirecting traveling of the coagulating fiber bundle by a first guide immersed in the coagulation bath disposed below the spinneret, and pulling it out of the coagulation bath liquid into the air to prepare a coagulated fiber bundle, which is then subjected to at least a washing step in water, stretching step, oil agent applying step, and drying step, wherein the depth-directional coagulation bath immersion length, which means a distance between the starting point of the immersion of the spinning dope solution in the coagulation bath liquid and the first guide immersed in the coagulation bath where traveling of the coagulating fiber bundle is redirected, is 3 to 40 cm.

Abstract: An object of the present invention is to shorten the aging time for a fuel cell. To achieve the object, a gas diffusion electrode medium product according to the present invention includes sulfuric acid in an amount of 1.1 ?g/cm2 or less. In addition, a polymer electrolyte fuel cell according to the present invention has the gas diffusion electrode medium product according to the present invention incorporated therein.

Abstract: In order to provide a gas diffusion electrode medium having high thermal conductivity despite having low density and excellent both in handleability and cell performance, provided is a gas diffusion electrode medium including carbon fiber felt including carbon fibers having an average fiber diameter of 5 to 20 ?m, wherein at least a part of the carbon fibers that constitute the carbon fiber felt have a flat part in which, in a plane view of a surface of the carbon fiber felt, a maximum value of a fiber diameter is observed to be 10 to 50% larger than the average fiber diameter, and a frequency of the flat parts at the surface of the carbon fiber felt is 50 to 200/mm2.

Abstract: A fuel cell with high productivity, high power generation performance and high durability is described, along with a gas diffusion electrode base material having a microporous layer on one side of an electrically conductive porous base material, where the electrically conductive porous base material contains carbon fiber and resin carbide and has a density of 0.25 to 0.39 g/cm3 and a pore mode diameter in a range of 30 to 50 ?m. The microporous layer contains a carbonaceous powder and a fluororesin and has a surface roughness of 2.0 to 6.0 ?m, a porosity of 50 to 95%, and a pore mode diameter of 0.050 to 0.100 ?m.

Abstract: The objective of the present invention is to provide a method which is for producing a gas diffusion electrode substrate having a high conductivity and a chemical resistance, and by which an increase in production cost can be suppressed. The present invention is a method for producing a gas diffusion electrode substrate in which a microporous layer is formed in a conductive porous body formed by bonding carbon fibers to each other by means of a cured product of a binder resin, the method having, in the following order: a binder resin impregnation step in which a carbon fiber structure is impregnated with a binder resin composition to obtain a pre-impregnated body; a coating step in which the surface of the pre-impregnated body is coated with a microporous layer coating solution; and a heat treatment step in which the pre-impregnated body that has been subjected to the coating step is heat-treated at a temperature of at least 200° C.

Abstract: The present invention provides a micro-porous layer which provides a fuel battery having high productivity, high power generation performance, and high durability. The present invention provides a micro-porous layer including fibrous carbohydrate having a fiber diameter of 5 nm-10 ?m and an aspect ratio of 10 or more. The carbohydrate has an oxygen/carbon element ratio of 0.02 or more.

Abstract: In order to provide a gas diffusion electrode medium having high thermal conductivity despite having low density and excellent both in handleability and cell performance, provided is a gas diffusion electrode medium including carbon fiber felt including carbon fibers having an average fiber diameter of 5 to 20 ?m, wherein at least a part of the carbon fibers that constitute the carbon fiber felt have a flat part in which, in a plane view of a surface of the carbon fiber felt, a maximum value of a fiber diameter is observed to be 10 to 50% larger than the average fiber diameter, and a frequency of the flat parts at the surface of the carbon fiber felt is 50 to 200/mm2.

Abstract: A method of producing a carbon fiber bundle suppresses penetration of a process oil agent into the fiber surface layer and suppresses adhesion between fibers and the generation of surface voids, and also provides a carbon fiber bundle. The carbon fiber bundle is characterized by having a crystallite size of 3.0 nm or less as measured by wide-angle X-ray diffraction, containing a point where the Si/C ratio is 10 or more as calculated by SIMS (secondary ion mass spectrometry) in the region ranging from 0 to 10 nm in depth from the fiber surface, and also showing a Si/C ratio of 1.0 or less as calculated by SIMS at a depth of 10 nm from the fiber surface.

Abstract: The purpose of the present invention is to provide an electrode which is used as a liquid flow-through device electrode and in which liquid flow-through resistance is reduced and the utilization efficiency of carbon fiber is enhanced. Another object of the present invention is to provide a redox flow battery having excellent charge-discharge performance by use of the electrode which is used for the liquid flow-through device. The present invention provides an electrode for a liquid flow-through device, the electrode essentially consisting of a carbon fiber nonwoven fabric, having a thickness of more than 0.40 mm, and having a through-hole disposed therein, or a non-through-hole disposed on one surface or both surfaces of the electrode.

Abstract: A fuel cell with high productivity, high power generation performance and high durability is described, along with a gas diffusion electrode base material having a microporous layer on one side of an electrically conductive porous base material, where the electrically conductive porous base material contains carbon fiber and resin carbide and has a density of 0.25 to 0.39 g/cm3 and a pore mode diameter in a range of 30 to 50 ?m. The microporous layer contains a carbonaceous powder and a fluororesin and has a surface roughness of 2.0 to 6.0 ?m, a porosity of 50 to 95%, and a pore mode diameter of 0.050 to 0.100 ?m.

Abstract: A method of producing a precursor fiber for carbon fiber includes extruding a polyacrylonitrile copolymer solution from a spinneret into the air, immersing it in a coagulation bath liquid stored in a coagulation bath, redirecting traveling of the coagulating fiber bundle by a first guide immersed in the coagulation bath disposed below the spinneret, and pulling it out of the coagulation bath liquid into the air to prepare a coagulated fiber bundle, which is then subjected to at least a washing step in water, stretching step, oil agent applying step, and drying step, wherein the depth-directional coagulation bath immersion length, which means a distance between the starting point of the immersion of the spinning dope solution in the coagulation bath liquid and the first guide immersed in the coagulation bath where traveling of the coagulating fiber bundle is redirected, is 3 to 40 cm.

Abstract: An object of the present invention is to provide an electrode which is used for a liquid flow-through device and in which liquid flow-through resistance is reduced and the utilization efficiency of the surface of carbon fiber is enhanced. Another object of the present invention is to provide a redox flow battery having excellent charge-discharge performance by use of the electrode which is used for the liquid flow-through device. The present invention provides an electrode to be used for a liquid flow-through device, the electrode including a plurality of sheets of carbon fiber nonwoven fabric each having irregularities on a surface of the sheet of carbon fiber nonwoven fabric being stacked or each having a through-hole on the carbon fiber sheet being stacked, and having inside of the electrode a plurality of gaps which is formed by recesses of the irregularities or the through-hole and is not opened in a thickness direction.

Abstract: The present invention provides a micro-porous layer which provides a fuel battery having high productivity, high power generation performance, and high durability. The present invention provides a micro-porous layer including fibrous carbohydrate having a fiber diameter of 5 nm-10 ?m and an aspect ratio of 10 or more. The carbohydrate has an oxygen/carbon element ratio of 0.02 or more.

Abstract: The purpose of the present invention is to provide an electrode which is used as a liquid flow-through device electrode and in which liquid flow-through resistance is reduced and the utilization efficiency of carbon fiber is enhanced. Another object of the present invention is to provide a redox flow battery having excellent charge-discharge performance by use of the electrode which is used for the liquid flow-through device. The present invention provides an electrode for a liquid flow-through device, the electrode essentially consisting of a carbon fiber nonwoven fabric, having a thickness of more than 0.40 mm, and having a through-hole disposed therein, or a non-through-hole disposed on one surface or both surfaces of the electrode.

Abstract: An object of the present invention is to provide an electrode which is used for a liquid flow-through device and in which liquid flow-through resistance is reduced and the utilization efficiency of the surface of carbon fiber is enhanced. Another object of the present invention is to provide a redox flow battery having excellent charge-discharge performance by use of the electrode which is used for the liquid flow-through device. The present invention provides an electrode to be used for a liquid flow-through device, the electrode including a plurality of sheets of carbon fiber nonwoven fabric each having irregularities on a surface of the sheet of carbon fiber nonwoven fabric being stacked or each having a through-hole on the carbon fiber sheet being stacked, and having inside of the electrode a plurality of gaps which is formed by recesses of the irregularities or the through-hole and is not opened in a thickness direction.

Abstract: A coagulated yarn, which is used to manufacture carbon fiber, is a coagulated yarn the surface hole diameter of which is 30 nm or less and the degree of swelling is less than 100% or a coagulated yarn the surface hole diameter of which is 30 nm or less and the inner hole diameter is 30 nm or less. The carbon fiber precursor fiber and the carbon fiber are obtained using such a coagulated yarn.

Abstract: The purpose of the present invention is to improve water drainage performance of a gas diffusion electrode including a carbon fiber nonwoven fabric. The present invention provides a gas diffusion electrode base material essentially consisting of a carbon fiber nonwoven fabric, wherein the carbon fiber nonwoven fabric has an in-plane basis weight pattern in which high basis weight regions having a relatively high basis weight and low basis weight regions having a relatively low basis weight are arranged, and the carbon fiber nonwoven fabric has on at least one surface an uneven pattern in which recesses and projections are arranged, the uneven pattern being formed independently of the basis weight pattern.

Abstract: A carbon foam obtained by heat-treating a mesophase pitch whose softening point is 300° C. or less according to an elevated flow tester, whose ratio (Daromatic/Daliphatic) of the absorption intensity of an aromatic C—H stretching vibration, measured with FT-IR, to the absorption intensity of an aliphatic C—H stretching vibration, measured with FT-IR, is 4.0 or less and whose optically anisotropic content is at least 80%, a graphite foam obtained by heat-treating the carbon foam recited above at a temperature of 2,000° C. or higher and production processes of these.

Abstract: A carbon foam obtained by heat-treating a mesophase pitch whose softening point is 300° C. or less according to an elevated flow tester, whose ratio (Daromatic/Daliphatic) of the absorption intensity of an aromatic C-H stretching vibration, measured with FT-IR, to the absorption intensity of an aliphatic C-H stretching vibration, measured with FT-IR, is 4.0 or less and whose optically anisotropic content is at least 80%, a graphite foam obtained by heat-treating the carbon foam recited above at a temperature of 2,000° C. or higher and production processes of these.

Abstract: A finder optical system for single-lens reflex photographic cameras wherein an even number at least four of small reflecting surfaces are arranged in front of a pentagonal prism of a single-lens reflex photographic camera in such a way that an image of optical information such as graduations on diaphragm dial or shutter speed dial is reflected consecutively by said small reflecting surfaces, whereafter said image of optical information is projected around the field of view in a finder, said finder optical system being capable of projecting an image of optical information free from difference in dioptor at any desired position around said field of view in the finder by changing locations and/or relative tilting angles of said small reflecting surfaces.