Abstract: A carbon fiber bundle is provided which can develop satisfactory interfacial adhesion to polyolefin-based resins, especially polypropylene resins. The carbon fiber bundle comprises a plurality of single fibers that was sized with a sizing agent comprising: a polymer having a main chain formed of carbon-carbon bonds, containing an acid group in at least part of side chains or at least a part of main chain ends, and representing an acid value of 23 to 120 mgKOH/g as measured in accordance with ASTM D1386; or a polymer having a main chain formed of carbon-carbon bonds and containing at least either of an epoxy group and an ester group in at least a part of side chains or at least a part of main chain ends.

Abstract: The present invention relates to a carbon fiber sizing agent comprised of water-soluble thermoplastic resin and amphoteric surfactant within a weight ratio range of 6/1 to 1/3, a carbon fiber sizing method comprising treating carbon fibers using a sizing liquid containing the aforementioned sizing agent, sized carbon fibers comprising adhering the aforementioned sizing agent to their surfaces, and a fabric that uses said carbon fibers. The carbon fiber sizing agent of the present invention has satisfactory solubility in water over a wide pH range, and is able to impart to carbon fibers adequate convergence for forming stable chopped carbon fibers, superior workability and satisfactory uniform tow dispersibility in water over a wide pH range. Since a fabric of the present invention demonstrates affinity to water over a wide pH range, it is suitable for applications such as immersing said fabric in an aqueous matrix in order to impregnate the fabric with that matrix.

Abstract: The present invention provides a sizing agent capable of imparting superior resin impregnation and adhesion with resin, and more particularly, a carbon fiber sizing agent that have satisfactory emulsification stability having stable process throughput and minimizes the changes over time in the sized carbon fibers. The carbon fiber sizing agent contains (A) a compound having at least one epoxy group per molecule, (B) an anionic surfactant having an ammonium ion as the counter ion, and (C) a nonionic surfactant wherein, the nonionic surfactant (C) is contained at 1/50 to ½ (weight ratio) relative to the anionic surfactant (B).

Abstract: A pressure vessel includes a vessel body and a fiber reinforced plastic layer formed on the surface of the vessel body, wherein the fiber reinforced plastic layer include fiber reinforced plastic in which reinforcing fibers are impregnated with plastic, a strand elastic modulus of the reinforcing fiber is 305 GPa or higher, and a tensile elongation of the reinforcing fiber is 1.45 to 1.70%. A carbon fiber for a pressure vessel has a strand elastic modulus of 305 GPa or higher and a tensile elongation of 1.45 to 1.70%.

Abstract: The present invention provides a sizing agent capable of imparting superior resin impregnation and adhesion with resin, and more particularly, a carbon fiber sizing agent that have satisfactory emulsification stability having stable process throughput and minimizes the changes over time in the sized carbon fibers. The carbon fiber sizing agent contains (A) a compound having at least one epoxy group per molecule, (B) an anionic surfactant having an ammonium ion as the counter ion, and (C) a nonionic surfactant wherein, the nonionic surfactant (C) is contained at {fraction (1/50)} to ½ (weight ratio) relative to the anionic surfactant (B).

Abstract: The present invention relates to a carbon fiber sizing agent comprised of water-soluble thermoplastic resin and amphoteric surfactant within a weight ratio range of 6/1 to 1/3, a carbon fiber sizing method comprising treating carbon fibers using a sizing liquid containing the aforementioned sizing agent, sized carbon fibers comprising adhering the aforementioned sizing agent to their surfaces, and a fabric that uses said carbon fibers. The carbon fiber sizing agent of the present invention has satisfactory solubility in water over a wide pH range, and is able to impart to carbon fibers adequate convergence for forming stable chopped carbon fibers, superior workability and satisfactory uniform tow dispersibility in water over a wide pH range. Since a fabric of the present invention demonstrates affinity to water over a wide pH range, it is suitable for applications such as immersing said fabric in an aqueous matrix in order to impregnate the fabric with that matrix.

Abstract: A sizing agent for carbon fiber comprising either a component (A) and a component (B), or alternatively, a component (A′), a component (B′) and a component (D), each of which is described below. Component (A): an epoxy compound with at least 1 epoxy group within each molecule, and with a surface energy of 17 to 34 mJ/m2; component (B): an epoxy compound with at least 1 epoxy group within each molecule, and with a surface energy of at least 35 mJ/m2; component (A′): an epoxy compound with at least 2 epoxy groups within each molecule, and with a surface energy of 17 to 34 mJ/m2; component (B′): an epoxy compound with at least 2 epoxy groups within each molecule, and with a surface energy of at least 35 mJ/m2; and component (D): an anionic surfactant with an aryloxy group as a hydrophobic group, with an ammonium ion as a counter ion, and with an alkylene oxide addition quantity of no more than 10 moles.

Abstract: A process is disclosed for producing carbon fibers with modified surfaces by electrolytic treatment. In the process, electric current is passed between carbon fibers and a counter electrode in an electrolytic solution to which an aromatic compound having at least one hydroxyl group and/or amino group is added.