Shin-Etsu Chemical Co., Ltd.

Masami Terashima

Toshio Takago

Hideo Hirasawa

Hiroyuki Koide

Takaaki Nagao

Yuichi Matsunaga

Kazuhiro Hamaguchi

Masatoshi Arai

Yoshio Inoue

Tadakatsu Shimada

Takeo Inoue

Osamu Sodeyama

Shiniti Sato

An optical fiber base material manufacturing apparatus including a reaction chamber; a burner that has a portion thereof inserted into the reaction chamber through an insertion opening that creates a connection between the inside and outside of the reaction chamber, and emits a flame toward a starting member positioned within the reaction chamber; and a seal connection member that creates an air-tight seal between the burner and the reaction chamber at the insertion opening. One end of the seal connection member firmly contacts the burner inserted therethrough, another end of the seal connection member firmly contacts the reaction chamber and has a through-hole formed therein through which the burner is inserted without contacting the seal connection member, and the seal connection member includes a connecting portion that connects the one end to the other end, while preventing transfer of stress between the one end and the other end.

Optical fiber base material manufacturing apparatus

There are disclosed a method for producing an optical fiber base material ingot comprising depositing a soot on a starting core member, and subjecting the soot to dehydration, vitrification by sintering, and then cylindrical grinding, wherein the cylindrical grinding is performed while a core portion central axis is brought into line with a rotation axis of cylindrical grinding machine, and an optical fiber base material ingot produced by the method. According to the present invention, there are provided an optical fiber base material ingot having excellent ingot roundness and excellent core portion eccentricity, and a production method capable of producing the optical fiber base material ingot in a short period of time.

Method for producing optical fiber base material ingot by grinding while core portion central axis is brought into line with rotational axis of grinding machine

An improvement is proposed in the process for the preparation of a porous silica glass preform as a precursor of optical fibers by the VAD method, in which fine silica particles produced by the flame hydrolysis of a silicon-containing compound are deposited on the lower end of a seed rod suspended at the lower end of a suspender rod rotated by a carriage in a vertical tubular reactor furnace to grow in the vertical direction. Instead of taking the fully grown porous preform out of the tubular furnace by pulling up as suspended on the suspender rod as is undertaken in the prior art, the seed rod is temporarily held by clamping with a holding device with disconnection from the suspender rod and the porous preform and seed rod are pulled up by a separate vertical driving device so that the overall height of the apparatus can be greatly decreased contributing to a reduction of the manufacturing cost of optical fibers of silica glass.

Method for pulling-up a porous silica glass preform

An improvement is proposed in the apparatus and method for the preparation of a transparent silica glass preform as a precursor of optical fibers by sintering and vitrifying a porous silica glass preform in a sintering furnace as vertically suspended at the lower end of a suspender rod rotated by a carriage. Different from the conventional process in which the porous preform is lowered into the sintering furnace and the transparent preform after vitrification is pulled up out of the furnace as suspended at the lower end of the suspender rod throughout, a separate vertical driving device is provided along with a horizontal driving device for the carriage so that the effective up-and-down stroke of the carriage can be greatly reduced and the apparatus as a whole can be by far more compact contributing to the reduction of the manufacturing costs of the optical fibers of silica glass.

Method of lowering and raising a optical fiber preform in a sintering

The invention discloses a novel cyclic organopolysiloxane compound having one or more of 3,3,3-trifluoropropyl groups and one or more of alkenyloxy groups, e.g. isopropenyloxy group of the formula --O--C(CH.sub.3).dbd.CH.sub.2, each directly bonded to the silicon atom in a molecule. This novel organopolysiloxane compound is useful as a crosslinking agent for a hydroxy-terminated diorganopolysiloxane and a formulation of a room temperature curable organopolysiloxane composition capable of giving a rubbery elastomer by curing is proposed comprising, each in a limited proportion, (a) a hydroxy-terminated diorganopolysiloxane, (b) the above disclosed novel cyclic organopolysiloxane having 2 or 3 alkenyloxy groups, (c) a second cyclic organopolysiloxane having 2 or 3 alkenyloxy groups each directly bonded to the silicon atom in a molecule and (d) a guanidino-containing organosilicon compound, e.g. 3-(tetramethylguanidino)propyl trimethyl silane, as a curing accelerator. This room temperature curable composition exhibits excellent curability and free from the problem of the formation of noxious condensation products as in the conventional RTV silicone rubber compositions.

Novel organosilicon compound and a room temperature curable

The room temperature curable organopolysiloxane composition of the invention comprises a dimethylpolysiloxane terminated at both molecular chain ends with silanolic hydroxy groups, an organocyclopolysiloxane, typically a cyclotetrasiloxane, having 2 or more alkenyloxy groups such as isopropenyloxy groups in a molecule as a crosslinking agent for the dimethylpolysiloxane and a guanidyl-containing organosilane or polysiloxane compound as a curing catalyst. The composition is capable of giving a cured rubbery elastomer when kept in a moisture-containing atmosphere at room temperature without the problems in the prior art compositions such as noxious condensation products or poor adhesion to the surface of the substrate on which the composition has been cured. The above mentioned organocyclopolysiloxane having alkenyloxy groups along with one or more of trihydrocarbylsiloxy groups or, typically, trimethylsiloxy groups bonded to the silicon atoms in the ring structure is a novel compound not described in any prior art literatures.

Organocyclopolysiloxane and a room temperature curable composition

The invention provides a novel room temperature-curable organopolysiloxane composition useful as an adhesive or a sealing material with remarkably extended workable time owing to the delayed surface filming. The base component in the composition is a conventional diorganopolysiloxane terminated with hydroxy groups at both molecular chain ends admixed with several known ingredients such as a cross linking agent, curing catalyst, filler and the like. The most characteristic ingredient in the composition effective to achieve the above mentioned desired property is a 1,1,1-trimethyl-3-hydrocarbyl-3,3-di(acylamino)disiloxane which belongs to a novel class of organopolysiloxane compounds and method is described for the preparation of these siloxane compounds.

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Ibaraki, Japan

Masami Terashima