Abstract: A method of producing a carbon fiber bundle is provided, involving performing a flame-proof treatment to a carbon-fiber-precursor acryl fiber bundle having a single-fiber fineness of 1.5 dtex or more and 5.0 dtex or less, and having a roundness of 0.7 or more and 0.9 or less in a cross-section shape perpendicular to a fiber axis of the single fiber to obtain a flame-proofed fiber bundle; and performing a carbonization treatment to the flame-proofed fiber bundle.

Abstract: Provided are: a carbon fiber bundle which has a large value of single-fiber fineness and excellent productivity and which, despite this, contains few interlaced single fibers therein and has excellent spreadability; and precursor fibers which are suitable for use in producing the carbon fiber bundle. The precursor fibers are a carbon-fiber-precursor acrylic fiber bundle which comprises a polyacrylonitrile copolymer comprising 95-99 mol % acrylonitrile units and 1-5 mol % hydroxyalkyl (meth)acrylate units and which has a single-fiber fineness of 1.5-5.0 dtex. In the acrylic fiber bundle, the cross-section of each single fiber which is perpendicular to the fiber axis has a shape that has a roundness of 0.9 or less.

Abstract: A carbon fiber bundle, wherein an average single-fiber fineness is from 1.0 to 2.4 dtex and a roundness is from 0.7 to 0.9 in a shape of a cross-section perpendicular to a fiber axis of a single fiber; the roundness being determined with equation (1): roundness=4?S/L2, where S is a cross-sectional area of the single fiber and L is a circumferential length of the single fiber, and S and L are obtained by observing, under an SEM, the cross-section of the single fiber perpendicular to the fiber axis of the single fiber and analyzing the obtained image.

Abstract: A carbon fiber bundle, wherein an average single-fiber fineness is from 1.0 to 2.4 dtex and a roundness is from 0.7 to 0.9 in a shape of a cross-section perpendicular to a fiber axis of a single fiber; the roundness being determined with equation (1): roundness=4?S/L2, where S is a cross-sectional area of the single fiber and L is a circumferential length of the single fiber, and S and L are obtained by observing, under an SEM, the cross-section of the single fiber perpendicular to the fiber axis of the single fiber and analyzing the obtained image.

Abstract: A carbon fiber bundle, wherein an average single-fiber fineness is from 1.0 to 2.4 dtex and a roundness is from 0.7 to 0.9 in a shape of a cross-section perpendicular to a fiber axis of a single fiber; the roundness being determined with equation (1): roundness=4?S/L2, where S is a cross-sectional area of the single fiber and L is a circumferential length of the single fiber, and S and L are obtained by observing, under an SEM, the cross-section of the single fiber perpendicular to the fiber axis of the single fiber and analyzing the obtained image.

Abstract: Provided are: a polyacrylonitrile-based precursor fiber for the production of a carbon fiber having a large single-fiber fineness, said precursor fiber ensuring high heat stability of a spinning dope and excellent productivity; and a copolymer suitable for the production of said precursor fiber. Also provided are: high-quality carbon fiber bundles which have a large single-fiber fineness and excellent productivity; a process for producing the same; and a process for producing flameproofed fiber bundles suitable for the production of the carbon fiber bundles. A polyacrylonitrile-based copolymer which comprises 93.0 to 99.4 mol % of acrylonitrile units, 0.5 to 4.0 mol % of (meth)acrylamide-based units, and 0.1 to 3.

Abstract: A carbon fiber bundle, wherein an average single-fiber fineness is from 1.0 to 2.4 dtex and a roundness is from 0.7 to 0.9 in a shape of a cross-section perpendicular to a fiber axis of a single fiber; the roundness being determined with equation (1): roundness=4?S/L2, where S is a cross-sectional area of the single fiber and L is a circumferential length of the single fiber, and S and L are obtained by observing, under an SEM, the cross-section of the single fiber perpendicular to the fiber axis of the single fiber and analyzing the obtained image.

Abstract: A carbon-fiber-precursor acryl fiber bundle, including a polyacrylonitrile-based copolymer that contains from 95 to 99 mol % of an acrylonitrile unit and from 1 to 5 mol % of a hydroxyalkyl (meth)acrylate unit, where the fiber bundle has a single-fiber fineness of from 1.5 dtex to 5.0 dtex and a roundness of from 0.75 to 0.9 in a cross-section shape perpendicular to a fiber axis of the single fiber; the roundness being determined with equation (1): roundness=4?S/L2, where S is a cross-sectional area of the single fiber and L is a circumferential length of the single fiber, and S and L are obtained by observing, under an SEM, the cross-section of the single fiber perpendicular to the fiber axis of the single fiber and analyzing the obtained image.

Abstract: Provided are: a polyacrylonitrile-based precursor fiber for the production of a carbon fiber having a large single-fiber fineness, said precursor fiber ensuring high heat stability of a spinning dope and excellent productivity; and a copolymer suitable for the production of said precursor fiber. Also provided are: high-quality carbon fiber bundles which have a large single-fiber fineness and excellent productivity; a process for producing the same; and a process for producing flameproofed fiber bundles suitable for the production of the carbon fiber bundles. A polyacrylonitrile-based copolymer which comprises 93.0 to 99.4 mol % of acrylonitrile units, 0.5 to 4.0 mol % of (meth)acrylamide-based units, and 0.1 to 3.

Abstract: Provided are: a carbon fiber bundle which has a large value of single-fiber fineness and excellent productivity and which, despite this, contains few interlaced single fibers therein and has excellent spreadability; and precursor fibers which are suitable for use in producing the carbon fiber bundle. The precursor fibers are a carbon-fiber-precursor acrylic fiber bundle which comprises a polyacrylonitrile copolymer comprising 95-99 mol % acrylonitrile units and 1-5 mol % hydroxyalkyl (meth)acrylate units and which has a single-fiber fineness of 1.5-5.0 dtex. In the acrylic fiber bundle, the cross-section of each single fiber which is perpendicular to the fiber axis has a shape that has a roundness of 0.9 or less.

Abstract: Disclosed are an acrylonitrile copolymer excellent in thermal stability as a solution (spinning dope) when dissolved in an amide solvent and capable of forming dense polyacrylonitrile fiber suitable for production of carbon fiber, an acrylonitrile copolymer solution in which the acrylonitrile copolymer is dissolved in an amide solvent, and a method for producing polyacrylonitrile precursor fiber for carbon fiber by use of the acrylonitrile copolymer solution. Specifically, an acrylonitrile copolymer contains a sulfonate group derived from a polymerization initiator in an amount of 1.0×10?5 equivalent/g or more, and the value (equivalent ratio) of (the content of a sulfate group derived from the polymerization initiator/the total content of the sulfonate group and the sulfate group) is 0.4 or less; an acrylonitrile copolymer solution contains the aforementioned acrylonitrile copolymer and an amide solvent.

Abstract: Disclosed are an acrylonitrile copolymer excellent in thermal stability as a solution (spinning dope) when dissolved in an amide solvent and capable of forming dense polyacrylonitrile fiber suitable for production of carbon fiber, an acrylonitrile copolymer solution in which the acrylonitrile copolymer is dissolved in an amide solvent, and a method for producing polyacrylonitrile precursor fiber for carbon fiber by use of the acrylonitrile copolymer solution. Specifically, an acrylonitrile copolymer contains a sulfonate group derived from a polymerization initiator in an amount of 1.0×10?5 equivalent/g or more, and the value (equivalent ratio) of (the content of a sulfate group derived from the polymerization initiator/the total content of the sulfonate group and the sulfate group) is 0.4 or less; an acrylonitrile copolymer solution contains the aforementioned acrylonitrile copolymer and an amide solvent.

Abstract: Disclosed is a program development support system so adapted as to integrally manage a variety of information necessary for the development of a program by creating necessary links between information such as source programs to be employed for the development of the program, program parts, tools, specifications, handling persons and so on, by managing such information as resource information and by retaining attribute information of the links.