Nippon Telegraph and Telephone Corporation

Nippon Telegraph and Telephone Public Corporation

Japan Gore-tex Inc.

Fumio Yamamoto

Shigekuni Sasaki

Shinji Ando

Toru Matsuura

Toshiaki Tamamura

Yasuko Maruo

Tohru Matsuura

Toshihiro Ichino

Shinsuke Matsui

Hiroshi Kato

Fusao Shimokawa

Takao Kimura

Shiro Nishi

Takayuki Wani

Naofumi Mushiake

Shinzo Yamakawa

Shinji Tsuru

Masaya Takahashi

Shinji Koike

Satoru Kurosawa

Mamoru Ishitani

Susumu Fujimori

Akira Iwasawa

Yukitoshi Takeshita

Yoshito Shuto

Makoto Wagatsuma

A water repellent coating composition comprises a fluororesin powder having a specific surface area ranging from 27 to 48 m.sup.2 /g and a molecular weight ranging from 10,000 to 100,000; an acrylic-silicone binder resin; and a solvent. The fluororesin may be preferably at least one resin selected from polytetrafluoroethylene resins, tetrafluoroethylene/perfluoro(alkyl vinyl ether) copolymer resins, and tetrafluoroethylene/hexafluoropropylene copolymer resins. The coating composition can be used in various fields including constructions, civil engineering, transportation, communication. The coating films and coated articles produced with the water repellent coating composition exhibit excellent water repellency, antisnow- or antiice-sticking properties, and weatherability.

Water repellent coating composition, and coated films and coated

A method for preparing aromatic compounds including 1,4-difluoropyromellitic dianhydride represented by formula (12): ##STR1## and 1,4-difluoropyromellitic acid represented by formula (15): ##STR2## by dehydrating or hydrolyzing and dehydrating precursors.

Method for preparing aromatic compounds

A composite polymer electrolyte membrane which includes an ion-conductive polymer gel contained and supported by a matrix material formed of a porous polytetrafluoroethylene membrane. The porous polytetrafluoroethylene membrane has an internal structure which defines a three-dimensional network of interconnected passages and pathways throughout the membrane. The composite polymer electrolyte membrane has a tensile break strength of at least 10 MPa in at least two orthogonal planar directions, ion conductivity of at least 1 mS/cm, and is useful as a separator between electrodes of a lithium secondary cell.

Composite polymer electrolyte membrane

A perfluorinated polyimide comprising a repeating unit represented by general formula (1): ##STR1## and a perfluorinated poly(amic acid) comprising a repeating unit represented by general formula (6): ##STR2## wherein R.sub.1 is a tetravalent organic group; and R.sub.2 is a divalent organic group, provided that chemical bonds between carbon atoms and monovalent elements contained in R.sub.1 and R.sub.2 are exclusively carbon-to-fluorine bonds; methods for preparing them; and optical material including the perfluorinated polyimide. 1,4-Bis(3,4-dicarboxytrifluorophenoxy)-tetrafluorobenzene dianhydride, 1,4-difluoropyromellitic anhydride, 1,4-bis(3,4-dicarboxytrifluorophenoxy)-tetrafluorobenzene, 1,4-difluoropyromellitic acid, and 1,4-bis(3,4-dicyanotrifluorophenoxy)-tetrafluorobenzene as well as methods preparing them. The perfluorinated polyimide has a thermal stability and has a low optical loss in an optical communication wavelength region (0.8 to 1.7 .mu.m).

A perfluorinated aromatic compound represented by general formula (7): ##STR1## wherein R.sub.3 is a tetravalent perfluorinated aromatic group represented by formula (8): ##STR2## wherein (R.sub.4)s are the same, each being a carboxyl group or a cyano group, or two adjacent (R.sub.4)s combine to form a divalent group represented by formula (10): ##STR3## provided that when R.sub.4 is a cyano group, R.sub.3 denotes said tetravalent perfluorinated aromatic group represented by formula (9).

Perfluorinated aromatic compounds

A polyimide optical waveguide comprising a core made of polyimide whose refractive index is controlled to a predetermined value by electron beam irradiation, and a cladding set in contact with the core and having a refractive index lower than that of the core.

Polyimide optical waveguide and method of manufacturing the same

Polimide optical waveguide

A polyimide optical material, composed of a perfluorinated polyimide having a perfluorinated repeating unit represented by general formula (1) ##STR1## wherein R.sub.1 is a tetravalent perfluorinated organic group; and R.sub.2 is a divalent perfluorinated organic group.

Polyimide optical material

A perfluorinated polyimide comprising a repeating unit represented by general formula (1): ##STR1## and a perfluorinated poly(amic acid) comprising a repeating unit represented by general formula (6): ##STR2## wherein R.sub.1 is a tetravalent organic group; and R.sub.2 is a divalent organic group, provided that chemical bonds between carbon atoms and monovalent elements contained in R.sub.1 and R.sub.2 are exclusively carbon-to-fluorine bonds; methods for preparing them; and optical material including the perfluorinated polyimide. 1,4-Bis(3,4-dicarboxytrifluorophenoxy)tetrafluorobenzene dianhydride, 1,4-difluoropyromellitic anhydride, 1,4-bis(3,4-dicarboxytrifluorophenoxy)tetrafluorobenzene, 1,4-difluoropyromellitic acid, and 1,4-bis(3,4-dicyanotrifluorophenoxy)tetrafluorobenzene as well as methods preparing them. The perfluorinated polyimide has a thermal stability and has a low optical loss in an optical communication wavelength region (0.8 to 1.7 .mu.m).

Perfluorinated polyimide, perfluorinated poly(amic acid), starting

An optical waveguide which has properties including low optical losses, facile fabrication, controllable core-cladding refractive index ratio, and a high heat resistance is provided. The optical waveguide for light transmission therethrough has a core made of a polyimide obtained from at least one tetracarboxylic acid dianhydride and at least one diamine. The polyimide is (a) a polyimide homopolymer derived from a diamine represented by formula [I] as follows: ##STR1## (b) a polyimide copolymer derived from at least one diamine including the diamine represented by the formula [I]; or (c) a mixture of the polyimide homopolymers.

Polyimide optical waveguide

A coated optical fiber comprising an optical fiber; a first layer of a thermoplastic rubber composition which is disposed around the circumference of the optical fiber, has a Young's modulus of 0.1 GPa or less, and is capable of extrusion coating; and a second layer of a thermoplastic resin composition which is disposed around the circumference of the first layer, has a linear expansion coefficient of 1.times.10.sup.-5.degree. C..sup.-1 or less and a Young's modulus of 5 GPa or more, and is capable of extrusion coating. The coated optical fiber has excellent transmission characteristics at low and high temperatures and is inexpensive.

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Katsuta, Japan

Fumio Yamamoto