Other

Asahi Glass Company, Limited

Hiroyuki Hirai

Shigeki Kobayashi

Kazuo Kato

Hiroki Kamiya

Jun Hoshikawa

Makoto Machida

A process for producing a tetrafluoroethylene polymer, which comprises polymerizing tetrafluoroethylene in an aqueous medium in the presence of a dispersant, a stabilizer and a polymerization initiator, wherein the polymerization initiator is a redox polymerization initiator comprising a halogen acid salt YXO /a sulfite Z SO wherein X is a chlorine atom, a bromine atom or an iodine atom, Y is a hydrogen atom, ammonium, an alkali metal or an alkaline earth metal, and Z is ammonium, an alkali metal or an alkaline earth metal. By this process, it is possible to obtain a tetrafluoroethylene polymer which is suitable for a stretching operation after paste extrusion.

Process for producing a tetrafluoroethylene polymer excellent in strength

A process for producing a tetrafluoroethylene polymer, which comprises polymerizing tetrafluoroethylene in an aqueous medium in the presence of a water-soluble initiator, wherein the water used for the polymerization is regulated to have a TOC of 100 ppb or lower and/or an electrical conductivity of 1.0 &mgr;S/cm or lower. When this process for producing a tetrafluoroethylene polymer is employed, a decrease or fluctuation in the polymerization rate during the polymerization of tetrafluoroethylene will be minimal, and a deterioration in the physical properties of the obtained tetrafluoroethylene polymer will be minimal.

Process for producing a tetrafluoroethylene polymer having high strength

A tetrafluoroethylene polymer is produced by polymerizing tetrafluoroethylene in the presence of an aqueous medium and a polymerization initiator, wherein the content of impurities (e.g. a saturated compound such as CH F or CHF and an unsaturated compound such as CF &boxH;CFH, CF &boxH;CH , CF &boxH;CFCl or CF &boxH;CHCl) in the tetrafluoroethylene is not more than 100 ppm. By this method, PTFE which is uniform and stretchable at a high stretch ratio and which is excellent in the fibrillation property and has a high break strength, can be obtained.

Process for producing a tetrafluoroethylene polymer

A method of producing a paraffin wax for aqueous dispersion polymerization of TFE which allows high speed aqueous dispersion polymerization of TFE with excellent polymerization behavior such as excellent dispersion stability and consistent production of PTFE having excellent physical properties, and a method of producing PTFE using the paraffin wax. Aqueous dispersion polymerization of tetrafluoroethylene (hereinafter referred to as TFE) is conducted in the presence of a paraffin wax, a polymerization initiator and an emulsifier at least once and then the paraffin wax is recovered. The recovered paraffin wax is used for aqueous dispersion polymerization of TFE in the presence of a polymerization initiator and an emulsifier.

Method of producing paraffin wax for aqueous dispersion polymerization of tetrafluoroethylene and method of producing a polytetrafluoroethylene using the same

A tetrafluoroethylene polymer having high stretchability, a fibrillatable character and a non-melt fabricable quality, which has a standard specific gravity of at most 2.160, and a tensile break strength of from 32.0N (3.26 kgf) to 49.0N (5.0 kgf) or an endothermic ratio of at most 0.15 as calculated from the measurement by differential thermal analysis. The tetrafluoroethylene polymer is suitable for stretching operation after paste extrusion.

Tetrafluoroethylene polymer for stretching

A silver halide photosensitive material for a color filter comprising at least three silver halide emulsion layers having different spectral sensitivities and each silver halide emulsion layer contains couplers which form blue, green and red by coupling reaction with the oxidation product of a developer, wherein the amount of the couplers in a red coloring layer is adjusted so that each transmission density of the yellow and magenta dye components measured when all the couplers in the red coloring layer are subjected to color development is 1.5 or more, and a black matrix part becomes substantially black of transmission density of 2.5 or more when all the couplers on a support are subjected to reaction.

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Ichihara, Japan

Hiroyuki Hirai