Abstract: Provided are fibers that have excellent mechanical properties such as strength and that do not result in the filament breakage during a manufacturing process. The fibers are vinylidene fluoride resin fibers including a plurality of vinylidene fluoride resin filaments, and having a degree of crystal orientation of 80% or more as determined on the basis of X-ray diffraction from the azimuth angle intensity distribution curve of 2?=20.8±1°, and a crystal size of 12 nm or less.

Abstract: Provided are fibers that have excellent mechanical properties such as strength and that do not result in the filament breakage during a manufacturing process. The fibers are vinylidene fluoride resin fibers including a plurality of vinylidene fluoride resin filaments, and having a degree of crystal orientation of 80% or more as determined on the basis of X-ray diffraction from the azimuth angle intensity distribution curve of 2?=20.8±1°, and a crystal size of 12 nm or less.

Abstract: Provided are vinylidene fluoride resin fibers having excellent mechanical characteristics such as strength. The vinylidene fluoride resin fibers are obtained using a plurality of vinylidene fluoride resin filaments, have a glass transition temperature of not lower than ?28° C., and have a thermal shrinkage at 100° C. of not less than 2%.

Abstract: A method for producing an undrawn polyglycolic acid-based resin yarn, including: a discharge step of discharging a molten polyglycolic acid-based resin through a spinneret, to thereby form a fibrous polyglycolic acid-based resin; a keeping step of keeping the fibrous polyglycolic acid-based resin for 0.0012 seconds or more after the discharge in an atmosphere having a temperature of not lower than 110.5° C. but not higher than a melting point of the polyglycolic acid-based resin; and a cooling step of cooling the fibrous polyglycolic acid-based resin obtained in the keeping step, to thereby obtain an undrawn polyglycolic acid-based resin yarn.

Abstract: A polyglycolic acid resin (PGA) composition which can be used as a packaging material or a material for a drilling downhole tool (member), the composition containing from 30 to 90 mass % of a PGA and from 70 to 10 mass % of an inorganic filler, wherein the percentage of mass loss of the PGA after immersion in water for 3 hours at a temperature of 120° C. is at least 20% and preferably at least 25%, and the deflection temperature under load is 120° C. or higher; and a method for producing a PGA composition, the method including a step of melt-kneading using an extruder.

Abstract: A water-disintegrable composite fiber comprising: a phase containing a polyglycolic acid resin; and a phase containing another resin having a mass loss of 25% or greater after immersion for 7 days in 80° C. pure water and having a glass transition temperature Tg of 25° C. or higher; the two phases extending continuously in the lengthwise direction; and the fiber having a side surface in which a region formed from the phase containing the polyglycolic acid resin is 50% or less in terms of area ratio, and a cross section in which a region formed from the phase containing the polyglycolic acid resin is 50% or greater in terms of area ratio.

Abstract: Biodegradable aliphatic polyester particles have: (A) an average particle diameter of 10 to 500 ?m, and (B) a quantity of heat of low-temperature crystallization calculated as an exotherm attending on crystallization, detected in the course of heating by DSC, of at least 1 J/g, and preferably: (C) a quantity of heat of crystal melting calculated as an endotherm attending on melting of a crystal, detected in the course of the heating, of less than 100 J/g, and (D) a difference between the quantity of heat of crystal melting and the quantity of heat of low-temperature crystallization of less than 90 J/g. A process for producing the particles comprises grinding a particular biodegradable aliphatic polyester having a weight average molecular weight of at least 50,000 at not lower than 0° C. and lower than the glass transition temperature of the polyester while applying high shearing force.

Abstract: A method for producing a polyglycolic acid fiber, including: obtaining undrawn yarns by melt spinning a polyglycolic acid resin; keeping the undrawn yarns under a temperature condition of 1 to 20° C.; obtaining drawn yarns by drawing the kept undrawn yarns; and, if necessary obtaining a staple fiber by cutting the drawn yarns.

Abstract: The invention provides biodegradable aliphatic polyester particles having the following physical properties: (A) the average particle diameter thereof is 5 to 500 ?m; and (B) the fracture stress of a columnar tablet obtained by molding the particles in a cylindrical mold by applying a load of 4 kgf/cm2 for 1 hour at a temperature of 40° C. is at most 500 gf/cm2, and preferably also having the following property: (C) the fracture stress of a columnar tablet obtained by molding the particles in a cylindrical mold by applying a load of 4 kgf/cm2 for 1 hour at a temperature of [the glass transition temperature (Tg) of a biodegradable aliphatic polyester +10° C.

Abstract: A method for producing an undrawn polyglycolic acid-based resin yarn, including: a discharge step of discharging a molten polyglycolic acid-based resin through a spinneret, to thereby form a fibrous polyglycolic acid-based resin; a keeping step of keeping the fibrous polyglycolic acid-based resin for 0.0012 seconds or more after the discharge in an atmosphere having a temperature of not lower than 110.5° C. but not higher than a melting point of the polyglycolic acid-based resin; and a cooling step of cooling the fibrous polyglycolic acid-based resin obtained in the keeping step, to thereby obtain an undrawn polyglycolic acid-based resin yarn.

Abstract: Biodegradable aliphatic polyester particles have: (A) an average particle diameter of 10 to 500 ?m, and (B) a quantity of heat of low-temperature crystallization calculated as an exotherm attending on crystallization, detected in the course of heating by DSC, of at least 1 J/g, and preferably: (C) a quantity of heat of crystal melting calculated as an endotherm attending on melting of a crystal, detected in the course of the heating, of less than 100 J/g, and (D) a difference between the quantity of heat of crystal melting and the quantity of heat of low-temperature crystallization of less than 90 J/g. A process for producing the particles, comprises grinding a particular biodegradable aliphatic polyester having a weight average molecular weight of at least 50,000 at not lower than 0° C. and lower than the glass transition temperature of the polyester while applying high shearing force.

Abstract: A method for producing a polyglycolic acid-based fiber, includes a spinning process of obtaining undrawn yarns by melt spinning a polyglycolic acid-based resin composition, which comprises a polyglycolic acid resin and a polylactic acid resin having a weight average molecular weight of 10×104 to 30×104 in a mass ratio of the polyglycolic acid resin to the polylactic acid resin of 70/30 to 99/1. The method also includes a keeping process of keeping the undrawn yarns and a drawing process of obtaining drawn yarns by drawing the kept undrawn yarns.

Abstract: A method for producing a polyglycolic acid fiber, including: obtaining undrawn yarns by melt spinning a polyglycolic acid resin; keeping the undrawn yarns under a temperature condition of 1 to 20° C.; obtaining drawn yarns by drawing the kept undrawn yarns; and, if necessary obtaining a staple fiber by cutting the drawn yarns.