Shin-etsu Chemical Co., Ltd.

Sony Corporation

Mitsubishi Cable Industries, Ltd.

Masatoshi Takita

Takaaki Shimizu

Minoru Takamizawa

Yoshiaki Hisagen

Shigetaka Higuchi

Toshio Shiobara

Tsutomu Ogihara

Koji Futatsumori

Eiichi Asano

Kazuhiro Arai

Hiroyuki Hayami

Koichi Suzuki

A silica glass optical fiber superior in resistance to ultraviolet rays, which fiber comprises a doped silica glass cladding layer formed on a silica glass core, said silica glass core having an OH content of 10-1000 ppm, a fluorine content of 50-5000 ppm, and being substantially free of chlorine.

Ultraviolet resistant silica glass fiber

A synthetic silica glass article made by hydrolyzing an alkoxysilane and thermally sintering the resulting silica; this synthetic silica glass article has a viscosity of not lower than 10.sup.10 poise at 1400.degree. C., and contains, as metallic impurities, less than 1 ppm of Al, less than 0.2 ppm of Fe, less than 0.2 ppm of Na, less than 0.2 ppm of K, less than 0.01 ppm of Li, less than 0.2 ppm of Ca, less than 0.02 ppm of Ti, less than 0.01 ppm of B, less than 0.01 ppm of P, less than 0.01 ppm of As.

Synthetic silica glass articles and a method for manufacturing them

High transparency silica-titania glass beads are characterized by a linear transmittance of at least 70% as measured at a wavelength of 900 nm to 600 nm by a specific measurement method. Such beads are prepared by hydrolyzing and polycondensing a silicon alkoxide and a titanium alkoxide to form a silica-titania sol, converting the sol into a dry gel, and then grinding the gel followed by heating or heating the gel followed by grinding. A light transmisson epoxy resin composition comprising a curable epoxy resin, a curing agent, and the high tranparency silica-titania glass beads has crack resistance and high transparency in cured state. It is useful in encapsulating optical semiconductor devices.

High transparency silica-titania glass beads, method for making, and

A synthetic silica glass article made by hydrolyzing an alkoxysilane and thermally sintering the resulting silica; this synthetic silica glass article has a viscosity of not lower than 10.sup.10 poise at 140.degree. C., and contains, as metallic impurities, less than 1 ppm at Al, less than 0.2 ppm of Fe, less than 0.2 ppm of Na, less than 0.2 ppm of K, less than 0.01 ppm of Li, less than 0.2 ppm of Ca, less than 0.02 ppm of Ti, less than 0.01 ppm of B, less than 0.01 of P, less than 0.01 ppm of As.

The invention provides a synthetic silica glass article or tool for a dopant-diffusing process in semiconductors, which is quite satisfactory in use in respect of the outstandingly small creeping at high temperatures, by working from a silica glass block having such a creeping characteristic that the elongation under a tension of 62.5 g/mm.sup.2 at a temperature of 1250.degree. C. does not exceed 0.025% after 5 minutes.

Synthetic silica glass article for dopant-diffusion process in

A method for manufacturing synthetic silica glass by reacting methyl silicate and aqueous ammonia, dispersing the silica particles produced in water, solidifying the silica by the addition of methyl silicate and heating, dehydrating, de-solventing, decarburizing and sintering the solid silica to produce a glass product. The sintered glass may be pulverized to produce a powder. The inventive method is easily carried out and avoids the high energy costs of the prior art. The glass product obtained exhibits excellent high temperature viscosity.

Method of manufacturing synthetic silica glass

A method for the preparation of a stable silica organosol in a hydrophobic organic solvent is proposed. The method comprises (a) hydrolyzing a tetraalkoxy silane, e.g. tetraethoxy silane, in an alcoholic medium in the presence of a limited amount of water and ammonia as a catalyst under controlled conditions so as to produce a silica alcosol in which the silica particles satisfy the requirements that the alkoxy groups and silanolic hydroxy groups are bonded to the silicon atoms on the surface in densities of at least 3.5 .mu. moles/m.sup.2 and not exceeding 2 .mu. mmoles/m.sup.2, respectively, and the specific surface area S given in m.sup.2 /g and the average particle diameter D given in nm of the silica particles satisfy the relationship of S.times.D.gtoreq.5000, D being 1 nm or larger, and (b) admixing the alcosol of silica particles with an organosilicon compound selected from the group consisting of the compounds represented by the general formula R.sub.4-n SiX.sub.n, (R.sub.3 Si).sub.2 NH, or YO--(--SiR.sub.2 --O--).sub.m --Y, in which each R is, independently from the others, a hydrogen atom or a monovalent hydrocarbon group, X is a hydroxy group or an alkoxy group, Y is a hydrogen atom or an alkyl group, n is 1, 2 or 3 and m is a positive integer not exceeding 20, in an amount, for example, in the range from 0.01 to 10 moles per mole of the silica particles under agitation of the mixture to effect a reaction for the modification of the surface of the silica particles followed by replacement of the alcoholic medium with a desired organic solvent.

Method for the preparation of surface-modified silica particles

The invention provides a method for the preparation of synthetic fused silica glass containing a very small amount of hydroxyl groups and has a high viscosity at high temperatures suitable for use as a material of articles for semiconductor processing at high temperatures, such as a crucible for Czochralski single crystal growing of semiconductor silicon. The method comprises hydrolyzing methyl silicate in a medium containing a specified amount of ammonia as a hydrolysis catalyst to form silica particles which are heat-treated in several successive steps.

Preparation of fused silica glass by hydrolysis of methyl silicate

A magnetic recording medium including a flexible non-magnetic film base and a magnetic layer thereon which contains and/or is coated with an organosilicon compound having lubricating properties, said compound having the following formula: ##STR1## WHERE R is a saturated or unsaturated aliphatic group having from 7 to 17 carbon atoms and n is an integer from 1 to 3. The static friction coefficient and the tendency of the magnetic layer to shed powder are both substantially reduced in the improved magnetic recording medium of the present invention.

Magnetic recording medium

A magnetic recording medium including a flexible non-magnetic film base and a magnetic layer thereon consisting of magnetizable particles in a resinous binder, the magnetic layer containing or being coated with an organosilicon lubricant compound having the formula:

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Niigata, Japan

Masatoshi Takita