Nippon Telegraph and Telephone Corporation

Nippon Telegraph and Telephone Public Corporation

Shigekuni Sasaki

Shinji Ando

Fumio Yamamoto

Toru Matsuura

Yoshinori Hasuda

Shiro Nishi

Toshiaki Tamamura

Kouzaburou Nakamura

Yasuko Maruo

Tohru Matsuura

Shinsuke Matsui

Toshihiro Ichino

Tooru Maruno

Fusao Shimokawa

Shinji Koike

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 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 process for the preparation of a polyetherimide/epoxyimide resin composition comprising (a) mixing a polyetherimide and an epoxyimide in a mixing ratio, by weight, of polyetherimide to epoxyimide of from 6:1 to 1:1 in a polar solvent to form a mixed resin composition, said polyetherimide being represented by the following formula of: ##STR1## said epoxyimide being represented by the following general formula of: ##STR2## wherein n is an integer from from 0 to 10; and R.sub.2 is a bifunctional organic radical residue selected from the group consisting of diphenylmethane, diphenyl ether, diphenyl sulfone, m-phenylene, p-phenylene and 1,6-hexamethylene; (b) molding said mixed resin composition prepared in the preceding mixing step, followed by removal of said polar solvent from the molded mixture; and (c) heating molded composition at a temperature of 100.degree. C. to 300.degree. C. for 1 to 3 hours.

Process for preparing polyetherimide/epoxyimide resin composition

The present invention provides a bis(hydroxyphthalimide) prepared by reacting 4-hydroxyphthalic anhydride and an organic diamine in the presence of an organic solvent under heating. The bis(hydroxyphthalimide) has two intramolecular imide rings and active hydrogens, and is thus polymerizable to form a variety of polycondensation products each having imide rings by condensation. The bis(hydroxyphthalimide) is also reacted with a dicarboxylic acid dihalide to form a polyesterimide, through condensation, which is excellent in transparency and heat resisting property.

Process for preparing polyesterimide from bis(hydroxyphthalimide)

A polyetherimide/epoxyimide resin composition prepared by mixing a polyetherimide having a repeating unit represented, for example, by the formula of: ##STR1## with an epoxyimide represented by the following general formula of: ##STR2## wherein R is, for example, selected from the group consisting of diphenyl ether, diphenylmethane, diphenyl sulfone, m-phenylene, p-phenylene and 1,6-hexamehtylene; in a mixing ratio, by weight, of preferably from 6:1 to 1:1. The resin composition is mixed in a solvent to form a solution from which a film may be formed through a flow-coating method. The film made of the polyetherimde/epoxyimide resin composition of the invention, after being removed of the solvent followed by thermal treatment at a temperature of 150.degree. C. to 220.degree. C. for 1 to 3 hours, has improved thermal resistance, adaptability for adhesive, and low moisture permeability.

Polyetherimide/epoxyimide resin composition

Bis(hydroxyphthalimide) and process for preparing the same, and process

A flexible optical solar reflector (FOSR) which may be also used as an outermost layer of a multilayer thermal insulator comprising:

Flexible optical solar reflector

The adhesive composition or compound of the invention comprises an epoxy resin, a reactive diluent and a hardener, and at least one of said components contains fluorine atoms. The adhesive composition containing fluorine atoms, according to the invention, provides a cured or hardened composition having small refractive index due to the presence of fluorine atoms. The refractive index of the hardened product may be freely controlled within the range of n.sub.D.sup.23 =1.415 to n.sub.D.sup.23 =1.570. The adhesive composition may be applied for the production of optical members for use in a communication system utilizing optical fibers or in a variety of optical instruments, and has improved heat resistance and adhesive property and is improved in matching of the refractive index with that of the material used for the optical member, such as optical fibers or glasses having lower refractive index used in a lens system.

Growing community of inventors

Iruma, Japan

Shigekuni Sasaki