Shin-etsu Chemical Co., Ltd.

Hitachi Cable, Inc.

Yoshinori Hida

Shohei Kozakai

Shigeru Mori

Noriyuki Meguriya

Motoo Fukushima

Akira Hayashida

Eiichi Tabei

Seizi Katayama

Akira Yoshida

Hiroshi Yoshioka

Kunio Itoh

Tomiya Abe

Hisashi Shimizu

Hiroshige Okinoshima

Fumio Okada

Hideki Asano

Kiyohiro Kondow

Hiroshi Kanbara

Toshio Oba

Yuji Hinoto

Nobuo Takasaka

Seiji Katayama

A composition comprising (a) an organopolysiloxane having a unit of the formula: RSiO.sub.3/2 wherein R is a substituted or unsubstituted monovalent C.sub.1-10 hydrocarbon group in its molecule and having at least 0.05 alkenyl groups each directly attached to a silicon atom per silicon atom, (b) an organohydrogenpolysiloxane having at least 2 hydrogen atoms each directly attached to a silicon atom per molecule, and (c) a platinum catalyst, maintains good light transmission in cured form when exposed to humidity or stresses and is thus suitable for forming cores of optical fibers.

Optical fibers and core-forming compositions

Polyorganosilanes are prepared by contact reaction of organodihalosilanes with alkali metal fine particles in an organic solvent. Prior to the contact reaction, a triorganohalosilane is contacted with the dispersion of alkali metal fine particles in organic solvent for removing reactive oxygen and moisture from the dispersion. Formation of a siloxane bond in the polysilane backbone is minimized, and polyorganosilanes having a minimal oxygen content are obtained.

Preparation of polyorganosilanes

Polysilanes are produced by reacting dihalosilanes in the presence of alkali metals, By carrying out the dihalosilane reaction in the presence of copper halide catalysts at temperatures of at least 100.degree. C., higher molecular weight polysilanes are obtained in acceptable yields.

Preparation of polysilanes

A UV curable composition of a specific organopolysiloxane having mercaptoalkyl and phenylene groups and a vinyl-containing organopolysiloxane cures into a film which emits little stimulative sulfur odor and has enough resistance to light or UV radiation to retain its as-cured properties even after long-term exposure to sunlight or UV radiation.

UV curable compositions of organopolysiloxane containing mercaptoalkyl

Provided herein is an ultraviolet-curable gel composition which comprises an organopolysiloxane as a principal component which is represented by the general structural formula below. ##STR1## where R.sup.1 is a C.sub.4-25 monovalent organic group containing therein 1 to 2 vinyl functional groups; R.sup.2 is a C.sub.1-18 monovalent organic group having no vinyl group capable of addition polymerization; R.sup.3 is a C.sub.2-4 divalent hydrocarbon group; R.sup.4 is a C.sub.1-9 substituted or unsubstituted hydrocarbon group of the same or different kind; a is an integer of 1 to 3; and n is an integer of 5 to 500.

Ultraviolet-curable gel composition

Whereas the mechanism for the crosslink formation in the curable organopolysiloxane composition of the invention is the ultraviolet-induced addition reaction between alkenyl, e.g., vinyl, groups in a diorganopolysiloxane and mercaptoalkyl groups in another organopolysiloxane as in conventional compositions, the mercaptoalkyl-containing organopolysiloxane used in the invention is, differently from those in conventional compositions, an organopolysiloxane of a three-dimensionally branched molecular structure as composed of the siloxane units of the formulas R.sup.1.sub.3 SiO.sub.0.5, R.sup.1.sub.a (HSR.sup.2)SiO.sub.(3-a)/2 and SiO.sub.2, in which R.sup.1 is, for example, a methyl or phenyl group, R.sup.2 is, for example, --CH.sub.2 CH.sub.2 CH.sub.2 -- and a is zero, 1 or 2, in a specified proportion. In addition, the vinyl group-containing siloxane units in the vinyl-containing diorganopolysiloxane are localized in the molecular structure forming two blocks each bonded to one of the terminal silicon atoms. The inventive composition is advantageous in respect of the greatly improved mechanical strengths of the cured silicone rubber obtained by irradiating the composition with ultraviolet light.

Ultraviolet-curable organopolysiloxane composition

The coated optical fiber of the invention is prepared by providing a coating layer of an ultraviolet-curable organopolysiloxane or a composition comprising the same and irradiating the coating layer with ultraviolet. Specifically, each of the terminal silicon atoms of the organopolysiloxane, which preferably has a linear molecular structure, has two or more ethylenically unsaturated polymerizable groups bonded thereto through an oxygen atom, such as CH.sub.2 .dbd.CHCOOCH.sub.2 CH.sub.2 --, [CH.sub.2 .dbd.C(CH.sub.3)COOCH.sub.2 ].sub.3 C--CH.sub.2 --and (CH.sub.2 .dbd.CHCOOCH.sub.2).sub.2 C(C.sub.2 H.sub.5)CH.sub.2 --. By virtue of this unique molecular structure of the organopolysiloxane, the coating layer is rapidly cured by ultraviolet irradiation to give a cured coating layer exhibiting very low water absorption and small temperature dependency of the Young's modulus at low temperatures.

Optical fiber coated with an organopolysiloxane curable with actinic rays

The surface-coated optical fiber of the invention is composed of a fibrous body of a vitreous material, e.g. fused quartz glass, and a coating layer thereon formed of a coating composition comprising an organosiloxane-modified organic polymer, of which the backbone is formed of recurring organic units such as a polybutadiene, an acrylic polymer and the like having modifying pendant groups containing an organosiloxane unit. The workability of the coating composition in the coating application is excellent so that a high uniformity is obtained in the coating layer in comparison with a coating composition comprising an unmodified organic polymer. The coating layer thus formed has a remarkably improved mechanical strength over a coating layer formed of an organopolysiloxane resin alone.

Surface-coated optical fiber

In the alkenyl-containing diorganopolysiloxane of the invention, the distribution of the alkenyl groups in the molecule is not random as in conventional alkenyl-containing diorganopolysiloxanes but each of at least three siloxane units linked to each of the terminal silicon atoms has an alkenyl, e.g. vinyl, group while at least six of the uninterruptedly linked siloxane units excepting the above mentioned alkenyl-containing units adjacent to the molecular chain ends are free from aliphatic unsaturation. A method for the preparation of the diorganopolysiloxane having the alkenyl groups in such a localized distribution is disclosed. When the diorganopolysiloxane is used as the principal ingredient of a curable organopolysiloxane composition as combined with a crosslinking agent, the composition, despite its relatively low viscosity, can give a cured rubber having markedly improved mechanical strengths.

Novel organopolysiloxane, method for the preparation thereof and

The inventive method for forming a cured film on a substrate surface comprises coating the surface with a room temperature curable organosiloxazane polymer comprising, in a molecule, (a) at least one organosiloxane unit represented by the unit formula (a) at least one organosiloxane unit represented by the unit formula

Method for forming a surface film of cured organosilicon polymer on a

The invention provides a novel silicone-coated, quartz glass-made optical fiber which is very advantageous in the high efficiency of the coating process as well as in the improved workability in the connecting works of the fiber terminals for extension of the communication lines by virtue of the excellent peelability of the coating layer from the surface of the quartz glass fiber even by mere drawing the coated fiber between fingers. The coating layer is formed of a radiation- or UV-cured silicone composition comprising (A-a) an organopolysiloxane having aliphatic unsaturation, e.g. vinyl, and/or (A-b) an organopolysiloxane having mercaptoalkyl groups, e.g. 3-mercaptopropyl groups, and (B) a curing accelerator.

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Kawasaki, Japan

Yoshinori Hida