Abstract: To provide a fiberboard capable of reducing a load on the environment at all states of producing, using, and abolishing and moreover having a high degree of bending strength and a high bending-strength retention rate at high temperature and high humidity so as to be usable for an automobile interior material or building material and a fiber-board producing method. The fiberboard is formed by mixing natural fiber with polylactic acid resin serving as a binder and has an apparent density of 0.2 g/cm3.

Abstract: A poly(lactic acid) fiber has a strength at 90° C. of equal to or more than 0.8 cN/dtex and exhibits significantly satisfactory mechanical properties at high temperatures as compared with conventional poly(lactic acid) fibers.

Abstract: The present invention offers polypropylene terephthalate textured yarn which has little dyeing unevenness or fibrillation, and is outstanding in its product quality, by carrying out texturing at the same time as drawing under specified conditions using polypropylene undrawn yarn; together with a method for the production thereof.

Abstract: A soft stretch yarn substantially comprising polyester fibers has a stress, at 50% yarn stretch, of no more than 30×10−3 cN/dtex and, at the same time, a percentage recovery of at least 60%. Preferably, the Uster unevenness is no more than 2.0% and the crimp diameter is no more than 250 &mgr;m. This soft stretch yarn can be produced by spinning yarn of conjugate fibers comprising two types of polyester in which one component is PTT at a take-up velocity of at least 1200 m/min, drawing at a drawing temperature of 50 to 80° C. at a draw ratio such that the drawn yarn tensile elongation is 20 to 45%, and then heat setting.

Abstract: A soft stretch yarn substantially comprising polyester fibers has a stress, at 50% yarn stretch, of no more than 30×10−3 cN/dtex and, at the same time, a percentage recovery of at least 60%. Preferably, the Uster unevenness is no more than 2.0% and the crimp diameter is no more than 250 &mgr;m. This soft stretch yarn can be produced by spinning yarn of conjugate fibers comprising two types of polyester in which one component is PTT at a take-up velocity of at least 1200 m/min, drawing at a drawing temperature of 50 to 80° C. at a draw ratio such that the drawn yarn tensile elongation is 20 to 45%, and then heat setting.

Abstract: A method for melt-spinning synthetic fiber, characterized by using a spinning device of which the part to be contacted with polymer in melt is coated with a film of an oxide, nitride or carbide of any of Si, Ti, Zr, Al, W, B, Ta and Ge or with a film of heat-resistant resin.

Abstract: This invention relates to a method and apparatus for producing a polyester fiber which cools a plurality of molten polyester fibers from a spinnert 2 to a temperature below a glass transition point, then takes up the fibers by a non-heating first godet roller at a take-up speed less than 4,000 m/min, heat-stretching the fibers between the first godet roller and a non-heating second godet roller 10 inside a normal pressure steam atmosphere (first heat-treating device 8) higher than the glass transition point of the polyester fiber, and heat-treats the fiber by a pressurized steam atmosphere (second heat-treating device 9) higher than 105.degree. C.