An acrylonitrile-containing fiber includes 100 parts by mass of a polymer including at least 15 parts by mass of acrylonitrile; and 1.0 to 50 parts by mass of a water absorbent resin having a pure water absorption capacity (g/g) with respect to its own weight of at least 10 but less than 100, wherein the fiber is dyeable with a disperse dye.

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. The roundness is a value determined using equation (1) where S and L are the cross-sectional area and the circumferential length, respectively, of a single fiber which are obtained by examining, with an SEM, the cross-section of the single fiber which is perpendicular to the fiber axis and analyzing the obtained image.

Roundness=4 pS/L.sup.2(1)

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. The roundness is a value determined using equation (1) where S and L are the cross-sectional area and the circumferential length, respectively, of a single fiber which are obtained by examining, with an SEM, the cross-section of the single fiber which is perpendicular to the fiber axis and analyzing the obtained image.

Roundness=4 pS/L.sup.2(1)

A process for preparing a PANOX fiber comprising: obtaining an acrylonitrile copolymer, wherein the copolymer contains at least about 2% by weight itaconic acid comonomer; forming a spin dope from the copolymer; wet spinning the spin dope to obtain gelled filaments; contacting the gelled filaments with ammonia activator in an aqueous imbibation bath; bundling the gelled filaments to obtain a fiber; removing solvent from the fiber; drawing the fiber; densifying the fiber by heating the fiber up to about 400 degrees C. for a time of about 15 minutes in a rapid densification zone; and withdrawing a PANOX fiber from the densification zone.

A process for preparing a PANOX fiber comprising: obtaining an acrylonitrile copolymer, wherein the copolymer contains at least about 2% by weight itaconic acid comonomer; forming a spin dope from the copolymer; wet spinning the spin dope to obtain gelled filaments; contacting the gelled filaments with ammonia activator in an aqueous imbibation bath; bundling the gelled filaments to obtain a fiber; removing solvent from the fiber; drawing the fiber; densifying the fiber by heating the fiber up to about 400 degrees C. for a time of about 15 minutes in a rapid densification zone; and withdrawing a PANOX fiber from the densification zone.

Acrylic compositions comprising a hindered amine light stabilizer are described herein. The acrylic composition may be in the form of a fiber, thread, yarn, and/or fabric. Also described herein are methods of making and using the acrylic compositions and articles comprising an acrylic composition as described herein.

A carbon fiber bundle is obtained by filtering a spinning dope solution in which a polyacrylonitrile copolymer is dissolved in a solvent, at a predetermined filtration speed, using a filter medium having a predetermined particle retention and a filter basis weight, then spinning the filtered spinning dope solution to obtain a precursor fiber bundle for carbon fiber, and heat-treating the obtained precursor fiber bundle for carbon fiber at an appropriate temperature profile in an oxidizing atmosphere until reaching a predetermined density to obtain an oxidized fiber bundle, and then heat-treating the oxidized fiber bundle at a predetermined temperature in an inert atmosphere.

The present invention relates to a method for producing an acrylonitrile-based fiber, the method including: providing a polymer solution including an acrylonitrile-based copolymer containing a carboxylic acid group; mixing 100 parts by weight of the polymer solution with 1 to 6 parts by weight of a hydrophilization solution containing an organic solvent and ammonia water in a weight ratio of 95:5 to 60:40 to prepare a spinning stock solution; and spinning the spinning stock solution. The method controls the viscosity of the spinning stock solution to improve the stretchability and strength of the acrylonitrile-based fiber, and suppresses the occurrence of gelation.

The present disclosure relates to an improved method for preparing carbon fiber via modified stabilization and carbonization methods during a process of forming filaments of co-polymers comprising acrylonitrile (AN) and vinyl imidazole (VIM) by adding an additive during the during the extrusion process to decrease stabilization temperature, increase crosslinking during oxidation, or decrease the temperatures of carbonization.

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=4S/L.sup.2, 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.