Abstract: There is disclosed a high-shrinkage acrylic fiber made of an acrylonitrile polymer comprising acrylonitrile in no less than 50% by weight, wherein a shrinkage rare after dry heating at 130° C. for 10 min without load is 25 to 35% and a difference between the maximum and the minimum of a shrinkage rate after dry heating within a temperature range of 120 to 140° C. for 10 min without load is 8% or less. There also provided a pile composition comprising the high-shrinkage acrylic in 20 to 80% by weight, and a pile fabric prepared from the pile composition.

Abstract: There is disclosed a high-shrinkage acrylic fiber made of an acrylonitrile polymer comprising acrylonitrile in no less than 50% by weight, wherein a shrinkage rate after dry heating at 130° C. for 10 min without load is 25 to 35% and a difference between the maximum and the minimum of a shrinkage rate after dry heating within a temperature range of 120 to 140° C. for 10 min without load is 8% or less. There are also provided a pile composition comprising the high-shrinkage acrylic fiber in 20 to 80% by weight, and a pile fabric prepared from the pile composition.

Abstract: The present invention is directed to chitosan-containing acrylic fibers having a total chitosan content of 0.05 to 2% by weight and an extractable chitosan content of not less than 0.03% by weight to less than the total chitosan content. The antimicrobial activity of the chitosan-containing acrylic fibers of the present invention can persist for a long period of time and is not deteriorated even when subjected to posttreatments, such as dyeing and bleaching of fibers, and treatments in usual service environments of fiber products, such as washing and ironing.

Abstract: The present invention is directed to chitosan-containing acrylic fibers having a total chitosan content of 0.05 to 2% by weight and an extractable chitosan content of not less than 0.03% by weight to less than the total chitosan content. The antimicrobial activity of the chitosan-containing acrylic fibers of the present invention can persist for a long period of time and is not deteriorated even when subjected to posttreatments, such as dyeing and bleaching of fibers, and treatments in usual service environments of fiber products, such as washing and ironing.

Abstract: Flat filaments have a flatness (A/B) of 7 to 25, where A is a length of at least one of the two longer sides of a substantially rectangular, transverse cross-section of each filament and B is a length of at least one of the two shorter sides of the substantially rectangular, transverse cross-section of each filament. The flat filaments also have a fineness of 0.5 to 40 denier, and are provided on each of the two longer sides with one or more ribs continuously extending in a direction of an axis of the filament and having a width W and a height H. The number of the ribs on each longer side ranges from 1 to A/2W, the rib width W ranges from B/2 to 3B, and the rib height H ranges from B/2 to 2B. The filaments have excellent nontackiness and bulkiness and permit easy elimination of crimps by polishing, and can be suitably used as raw fibers which, when formed into a pile product, provide the pile product not only with a soft feeling but also with resilient and substantial feeling.

Abstract: A carbon based porous hollow fiber membrane excellent in heat resistance wherein it has pores which continuously penetrate from inner wall surface to outer wall surface of the membrane, maximum value of pore radius obtained from pore volume differential curve is in 10-1000 nm, total pore volume is 0.1-1 cm.sup.3 /g, curvature radius at flexing is 10 cm or less, and temperature at which 10% by weight of the membrane is decomposed and which is measured by TGA is at least about 300.degree. C. and a method for producing the abovementioned carbon based porous hollow fiber membrane having excellent heat resistance, characterized by comprising mixing an acrylonitrile based polymer (A) containing 90-100 mol % of acrylonitrile unit, a heat decomposable polymer (B) which is heat decomposed at a temperature of 600.degree. C.

Abstract: A process for producing an acrylic fiber comprising the steps of:(a) dissolving a polymer having a weight-average molecular weight of at least 5.times.10.sup.5 and containing at least 80 wt. % acrylonitrile in a solvent comprising dimethylformamide or dimethylacetamide at a polymer concentration of 5-15 wt. % to provide a spinning solution having a viscosity of 500-1,500 poises at 45.degree. C.;(b) extruding the solution into a gaseous medium to form filaments;(c) introducing the filaments into a coagulation bath comprising water and at least one of dimethylformamide and dimethylacetamide at 0.degree. C. or below; and(d) stretching the coagulated filaments to a draw ratio of at least 3 to provide an acrylic fiber having at least 90% X-ray orientation and an X-ray crystallinity parameter of up to 1 degree. The resulting acrylic fiber has high strength and high modulus.