Abstract: Provided is a tire whose durability is improved by using, as a reinforcing member, a polyester cord having an improved heat resistant adhesive property to rubber. Provided is a tire in which a rubber-cord complex composed of a polyester cord and a rubber is used as a reinforcing member. The polyester cord is formed by twisting polyester filaments, and then subjecting the twisted filaments to an adhesive agent treatment. The polyester filament is made of a polyester fiber which is composed of a polyester having ethylene terephthalate as a main repeating unit and having an intrinsic viscosity of 0.85 or higher, wherein the amount of terminal carboxy group in the fiber is 20 equivalent/ton or larger, the long period according to small-angle X-ray diffraction is 9 to 12 nm, and a surface treatment agent having an epoxy group is attached to the surface of the fiber.

Abstract: Provided is a tire whose durability is improved by using, as a reinforcing member, a polyester cord having an improved heat resistant adhesive property to rubber. Provided is a tire in which a rubber-cord complex composed of a polyester cord and a rubber is used as a reinforcing member. The polyester cord is formed by twisting polyester filaments, and then subjecting the twisted filaments to an adhesive agent treatment. The polyester filament is made of a polyester fiber which is composed of a polyester having ethylene terephthalate as a main repeating unit and having an intrinsic viscosity of 0.85 or higher, wherein the amount of terminal carboxy group in the fiber is 20 equivalent/ton or larger, the long period according to small-angle X-ray diffraction is 9 to 12 nm, and a surface treatment agent having an epoxy group is attached to the surface of the fiber.

Abstract: There is provided a polyester fiber which has few defects such as voids due to catalyst particles, and low variation in physical properties and minimal fluff generation. The polyester fiber of the invention comprises laminar nanoparticles composed of a divalent metal and a phosphorus compound and having side lengths of 5-100 nm and an interlayer spacing of 1-5 nm. There are also provided a tire cord, tire, belt-reinforcing fiber material and belt, comprising the polyester fiber.

Abstract: Polyethylene naphthalate fibers that are characterized in that the fibers have a crystal volume of from 550 to 1,200 nm3 obtained by wide angle X-ray diffraction of the fiber and a degree of crystallization of from 30 to 60%. It is preferred that the fibers have a maximum peak diffraction angle of wide angle X-ray diffraction of from 25.5 to 27.0° and a melting point of from 285 to 315° C. The production method thereof is characterized in that a particular phosphorus compound is added to the polymer in a molten state, the spinning draft ratio after discharging from the spinneret is from 100 to 5,000, and the molten polymer immediately after discharging from the spinneret is allowed to pass through a heat-retaining spinning chimney at a temperature within ±50° C. of a temperature of the molten polymer, and is drawn.

Abstract: Polyethylene naphthalate fibers that are characterized in that the fibers have a crystal volume of from 100 to 200 nm3 obtained by wide angle X-ray diffraction of the fiber and a degree of crystallization of from 30 to 60%. It is preferred that the fibers have a maximum peak diffraction angle of wide angle X-ray diffraction of from 23.0 to 25.0°. The production method thereof is characterized in that a particular phosphorus compound is added to the polymer in a molten state, the spinning speed is from 4,000 to 8,000 m/min, and the molten polymer immediately after discharging from the spinneret is allowed to pass through a heated spinning chimney at a high temperature exceeding a temperature of the molten polymer by 50° C. or more, and is drawn.

Abstract: The polyethylene naphthalate fiber for industrial material having a low fatigue in a composite is a polyethylene naphthalate fiber for industrial material containing an ethylene-2,6-naphthalate unit in 80% or more, characterize by having a strength of 6 cN/dtex or more and a secondary yield point elongation degree of 8% or less. The production method thereof is a method for producing a fiber in which a fiber having been obtained by melt-spinning a polyethylene naphthalate is subjected to stretching, characterized in that prestretch satisfying such conditions as the fiber temperature of from 80° C. to 120° C. and from 0.05 to 0.3 N/dtex is performed, a first stretch satisfying such conditions as the fiber temperature of from 130° C. to 180° C. and stretch tensile force of not more than the prestretch tensile force is performed, the total stretch magnification including subsequent stretches is set to 5 or more, and finally heat-treatment under tension with a stretch ratio of from 0 to 2% is performed.

Abstract: Polyethylene naphthalate fibers that are characterized in that the fibers have a crystal volume of from 550 to 1,200 nm3 obtained by wide angle X-ray diffraction of the fiber and a degree of crystallization of from 30 to 60%. It is preferred that the fibers have a maximum peak diffraction angle of wide angle X-ray diffraction of from 25.5 to 27.0° and a melting point of from 285 to 315° C. The production method thereof is characterized in that a particular phosphorus compound is added to the polymer in a molten state, the spinning draft ratio after discharging from the spinneret is from 100 to 5,000, and the molten polymer immediately after discharging from the spinneret is allowed to pass through a heat-retaining spinning chimney at a temperature within ±50° C. of a temperature of the molten polymer, and is drawn.

Abstract: There is provided a polyester fiber which has few defects such as voids due to catalyst particles, and low variation in physical properties and minimal fluff generation. The polyester fiber of the invention comprises laminar nanoparticles composed of a divalent metal and a phosphorus compound and having side lengths of 5-100 nm and an interlayer spacing of 1-5 nm. There are also provided a tire cord, tire, belt-reinforcing fiber material and belt, comprising the polyester fiber.

Abstract: Polyethylene naphthalate fibers that are characterized in that the fibers have a crystal volume of from 100 to 200 nm3 obtained by wide angle X-ray diffraction of the fiber and a degree of crystallization of from 30 to 60%. It is preferred that the fibers have a maximum peak diffraction angle of wide angle X-ray diffraction of from 23.0 to 25.0°. The production method thereof is characterized in that a particular phosphorus compound is added to the polymer in a molten state, the spinning speed is from 4,000 to 8,000 m/min, and the molten polymer immediately after discharging from the spinneret is allowed to pass through a heated spinning chimney at a high temperature exceeding a temperature of the molten polymer by 50° C. or more, and is drawn.

Abstract: The polyethylene naphthalate fiber for industrial material having a low fatigue in a composite is a polyethylene naphthalate fiber for industrial material containing an ethylene-2,6-naphthalate unit in 80% or more, characterize by having a strength of 6 cN/dtex or more and a secondary yield point elongation degree of 8% or less. The production method thereof is a method for producing a fiber in which a fiber having been obtained by melt-spinning a polyethylene naphthalate is subjected to stretching, characterized in that prestretch satisfying such conditions as the fiber temperature of from 80° C. to 120° C. and from 0.05 to 0.3 N/dtex is performed, a first stretch satisfying such conditions as the fiber temperature of from 130° C. to 180° C. and stretch tensile force of not more than the prestretch tensile force is performed, the total stretch magnification including subsequent stretches is set to 5 or more, and finally heat-treatment under tension with a stretch ratio of from 0 to 2% is performed.

Abstract: There is provided polyester multifilaments for resin reinforcement which are satisfactorily homogeneously dispersed in a matrix resin to provide a filament-reinforced resin molded body excellent in mechanical characteristics and impact resistance. Polyester multifilaments for resin reinforcement to which a thermosetting resin is attached in an amount of 0.01 to 5.0% by weight based on the polyester multifilaments, and preferably the polyester multifilaments for resin reinforcement, wherein the length of multifilament bundle portions satisfying 1?Y/X?3 (wherein X represents the width of the multifilaments before immersion in water and Y represents the width of the multifilaments after immersion in water at 25° C. for 1 minute) is 50% or more of the length of the multifilaments before the immersion.