Abstract: Disclosed is a method of manufacturing a preform for producing a plastic optical component comprising a graded-index core portion and a cladding portion in which the refractive index of the core portion continuously decreases from its center to the outer radius, and the refractive index of the cladding portion is smaller than that of the center of the core portion by 0.03 or more, comprising a first step of fabricating a polymer hollow tube for the cladding portion in which the inner wall of the polymer hollow tube has an arithmetic mean roughness of less than 0.4 ?m; and a second step of polymerizing a polymerizable composition in the hollow portion of the hollow tube to thereby form the core portion.

Abstract: A clad tube (21) is formed by melting and extruding a polymer, such as PMMA. The molten polymer is extruded through an extrusion die (12) to form a soft clad (20). The soft clad (20) is forwarded to a molding die (13) to correct the shape of the soft clad (20). A decompression chamber (31) in the molding die (13) is decompressed so that the outer surface of the soft clad (20) is tightly in contact with forming surface (30b) of the molding die (13). After molding the soft clad (20) in the molding die (13), the clad tube (20) with low fluctuation in thickness is obtained.

Abstract: A novel process for producing an optical transmission medium comprising a drawing step of drawing a molten portion of a preform to form the optical transmission medium is disclosed. In the process, the preform is heated by irradiation with laser light thereby being partially molten, and desirably rotated in a fixed direction, during the drawing step. An apparatus comprising a means for heating and melting partially a preform by irradiation with laser light and a means for drawing a molten portion of the preform is also disclosed. A novel plastic optical transmission medium is formed of a plastic wherein molecules are oriented in a certain direction not in parallel to the longitudinal direction of said medium is also disclosed.

Abstract: A process for producing a plastic optical member is provided that includes injecting a polymerizable monomer composition into a hollow plastic tube and polymerizing the composition within the hollow tube, wherein prior to injecting the composition one end of the hollow tube is sealed with a resin. The resin may have a composition different from that of the plastic forming the hollow tube. A process for producing a plastic optical fiber base material is also provided that includes injecting a polymerizable monomer composition into a hollow plastic tube and polymerizing the composition within the hollow tube, wherein prior to injecting the composition one end of the hollow tube is sealed with a resin. Furthermore, a process for producing a plastic optical fiber is provided that includes drawing the plastic optical fiber base material obtained by the above process. Moreover, also provided are a plastic optical member and a plastic optical fiber, which are produced by the above processes.

Abstract: The present invention discloses a method for producing plastic optical member comprising a core region and a clad region. The method comprises carrying out polymerization of a polymerizable monomer, thereby obtaining an area corresponding to the core region. The Polymerization is carried out in the presence of a polymerization initiator having a ten-hour, half-life decomposition temperature Th (° C.) (Tb−20≦Th; Tb is the boiling point (° C.) of the polymerizable monomer), at an initial polymerization temperature T1 (° C.) (Tb−10≦T1≦Tg; Tg is the glass transition point (° C.) of the polymer made of the polymerizable monomer), for a period which is equal to or longer than 10% of the half-life of the polymerization initiator at T1; and further carried out at an elevated temperature T2 (° C.

Abstract: This invention provides a method of producing polyester and charging apparatus therefor capable of producing a high quality polyethylene naphthalate usable for photographic purpose from recovered polyethylene naphthalate which comprises subjecting an ester-forming derivative consisting essentially of naphthalene dicarboxylic acid or its lower alkyl ester and a diol compound consisting essentially of ethylene glycol to ester exchange reaction or esterification to produce polyethylene naphthalate, wherein recovered polyethylene naphthalate resin is charged before beginning of effusion of alcohol or water which is a by-product of the ester exchange reaction or esterification, and a charging apparatus comprising a slidable inner pipe capable of penetrating through a supply valve.

Abstract: In a polymerization apparatus in which the power of a motor is transmitted to a stirrer via oil-lubricated transmission box and speed reduction gear, the temperature of the lubricating oil in the transmission box and speed reduction gear is maintained constant by means of a heat exchanger, the torque between the motor and the transmission box or the speed reduction gear is measured with a torque meter, the viscosity of a reaction mixture is calculated from the measured torque and the number of rotation of the stirrer, and the stirrer is kept revolving until the calculated viscosity of the reaction mixture reaches a prescribed value.

Abstract: Disclosed is a process for the preparation of polyester having an ethylene-terephthalate recurring-unit in the amount of not less than 60 molar % of the total recurring-unit of the polyester by polymerizing a bifunctional carboxylic acid comprising terephthalic acid and glycol comprising ethylene glycol in the presence of an antimony compound, at least one metal compound selected from the group consisting of a glycol-soluble magnesium compound, a glycol-soluble manganese compound and a glycol-soluble zinc compound, a hindered phenol compound, and a sulphur-containing ester compound, wherein the metal compound, the hindered phenol compound and a sulphur-containing ester compound are employed under the following conditions:0.015.ltoreq.A.ltoreq.0.15 (I)0.01.ltoreq.B.ltoreq.0.2 (II)0.01.ltoreq.C.ltoreq.0.2 (III)0.5.ltoreq.B/C.ltoreq.2.

Abstract: A method for controlling synthesis reaction of a synthetic high molecular resin, the method measuring continuously an infrared spectral absorption of a reaction intermediate product of polycondensation reaction. And the method controls reaction conditions on the basis of the measured infrared spectral absorption.