Shin-etsu Chemical Co., Ltd.

Taishi Kobayashi

Minoru Takamizawa

Akira Hayashida

Tatsuhiko Hongu

Yoshihumi Takeda

Morinobu Endou

Toshinobu Ishihara

Takaaki Shimizu

Hiromi Ohsaki

Mitsuo Umemura

Morinobu Endo

Nobuaki Urasato

Hironori Iwasaki

Shinichiro Akase

Takasi Toide

Nichiro Suzuki

Carbon tetrachloride, which is a material of low value and may be banned due to the problem of the destructiveness against the stratospheric ozone layer, can be efficiently utilized in the preparation of more useful methyl chloride by a catalytic vapor-phase reaction in a vapor mixture of carbon tetrachloride, methyl alcohol and water. The solid catalyst with which the vapor mixture is contacted at 150.degree. to 250.degree. C. is, for example, a zinc chloride catalyst supported on an active carbon carrier. The conversion of carbon tetrachloride is almost 100% when the contacting time is 10 to 20 seconds.

Method for preparation of methyl chloride

The invention provides a novel method for the preparation of a finely divided powder of silicon carbide as a promising material for sintered ceramic products of silicon carbide. The method comprises vapor-phase pyrolysis of a vaporizable organosilicon compound having, in a molecule, at least two, e.g. 2, 3 or 4, silicon atoms and at least one hydrogen atom directly bonded to the silicon atom but having no oxygen or halogen atom directly bonded to the silicon atom at a temperature of 750.degree. C. or higher.

Method for the preparation of a fine powder of silicon carbide

The precursor composition of silicon carbide fibers provided by the invention has greatly improved spinnability and can be spun at a very high spinning velocity to give a green filament which has a much larger tensile strength than those of conventional precursor materials and is capable of giving silicon carbide fibers having increased tensile strength by the infusibilization and calcination of the green filament of the composition under tension. The composition comprises from 80 to 99.9 parts by weight of a polycarbosilane polymer and from 20 to 0.01 part by weight of a silmethylene polymer having a degree of polymerization larger than the specified lower limit.

Precursor composition of silicon carbide

The invention provides a novel inorganic fiber composed of the elements of silicon, carbon, boron and nitrogen of which the Si/B molar ratio is 2:1 to 200:1. The inorganic fiber is obtained by a method comprising the steps of: (a) preparing an organoborosilicon polymer by heating a mixture of an organopolysilane and an organoborazine compound, e.g. B-trimethyl-N-triphenyl borazine, to effect thermal decomposition and polycondensation reaction; (b) spinning the polymer into a fibrous form; (c) infusibilizing the fiber of the polymer by thermally oxidizing in an oxidizing atmosphere or by irradiating with ionizing radiations; and (d) calcining the infusibilized fiber at 900.degree. to 1800.degree. C. The inventive inorganic fiber is more stable at high temperatures than conventional silicon carbide fibers.

Method for the preparation of an inorganic fiber containing silicon,

The liquid detergent composition of the invention comprises a halogenated hydrocarbon solvent, e.g. methylene chloride, an anionic and/or non-ionic surface active agents, a quaternary ammonium hydroxide, e.g. tetramethyl ammonium hydroxide and choline, and, optionally, a lower aliphatic alcohol, e.g. methyl alcohol, each in a limited proportion. The detergent composition is very effective in the cleaning works of articles of a transparent plastic resin, e.g. polycarbonate resin, and metal or glass molds for the preparation of such resin articles by casting polymerization, of which uppermost cleanness on the surface is very essential in respect of oily, greasy and resinous contaminants.

Liquid detergent composition

The invention provides a method for the preparation of an ultrafine powder of silicon carbide having an extremely fine and uniform particle size distribution of spherical agglomerate particles each formed of crystallites of 5 nm or smaller in size. The silicon carbide powder is prepared by the vapor phase pyrolysis of a specified methyl hydrogen(poly)silane as diluted with a carrier gas, e.g. hydrogen, to give a concentration of 40% by volume or lower at a temperature of 750.degree. to 1600.degree. C. The silicon carbide powder can readily be sintered at a temperature of 1750.degree. to 2500.degree. C. even without addition of a sintering aid to give a sintered body of extremely high density reaching 80% or larger of the theoretical value which can never be obtained of the conventional silicon carbide powders.

Ultrafine powder of silicon carbide, a method for the preparation

The invention provides a method for providing a highly protective coating layer of silicon carbide on to the surface of a substrate. The method comprises pyrolyzing the vapor of an organosilicon compound having at least one hydrogen atom directly bonded to the silicon atom in a molecule but having no halogen or oxygen atom directly bonded to the silicon atom at a temperature of 700.degree. to 1400.degree. C. in contact with the substrate surface to deposit silicon carbide thereon. In particular, the method is useful to form a sheath-and-core structure composed of the core of carbon filament and the coating layer of silicon carbide so that the carbon fibers are imparted with greatly improved resistance against oxidation and chemicals including molten metals when the carbon fibers are used as a reinforcing material of a fiber-reinforced metal composite as well as with improved affinity with molten resins and metals which is also an advantageous property as a reinforcing material for such matrix materials.

Method for providing a coating layer of silicon carbide on substrate

The invention provides a novel organoborosilicon polymer comprising two types of the recurring monomeric units represented by the general formulas of, one, --SiR.sup.1.sub.2 --CH.sub.2 -- and, the other, --BR.sup.2 --NR.sup.3 --, in which R.sup.1, R.sup.2 and R.sup.3 are each a hydrogen atom or a monovalent hydrocarbon group. Such an organoborosilicon polymer is readily prepared by the thermal decomposition polymerization reaction of an organopolysilane compound and a borazine compound at 250.degree. to 500.degree. C. and useful as a precursor of an inorganic ceramic material or inorganic fibers or as a binder of ceramics.

Organoborosilicon polymer and a method for the preparation thereof

The invention provides a novel method for the preparation of silicon carbide fibers capable of being performed at a relatively low temperature and giving fibers of relatively large lengths by the vapor-phase pyrolysis of an organosilicon compound on a substrate. The method comprises contacting an organosilicon compound, which should have no halogen and oxygen atoms directly bonded to the silicon atoms and have preferably at least one hydrogen atom directly bonded to the silicon atom in a molecule, with a finely divided powder of a metal or a compound of a metal, such as copper, silver, vanadium, niobium, tantalum, iron, cobalt, nickel, palladium and platinum, at a temperature of 700.degree. to 1450.degree. C. so that the powder serves simultaneously as a catalyst and nucleus for the growth of the silicon carbide fibers thereon formed by the pyrolysis of the organosilicon compound. When the organosilicon compound is deficient of the carbon content relative to the silicon so that free silicon may be formed by the pyrolysis, admixing of a hydrocarbon to the feed of the organosilicon compound can solve the problem.

Method for the preparation of silicon carbide fibers

The invention provides a novel and efficient method for the preparation of methyl hydrogensilanes, e.g. dimethyl silane, 1,1,2,2-tetramethyl disilane and 1,1,2,2,3,3-hexamethyl trisilane, with large demand in the industry of silicones as an intermediate for the synthesis of other valuable organosilicon compounds such as methyl hydrogenchlorosilanes. The inventive method comprises pyrolysis of a methyl polysilane composed of at least 60% by moles of dimethylsilicon units, the balance being monomethyl- and trimethylsilicon units, at a temperature in the range from 350.degree. to 800.degree. C.

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Niigata, Japan

Taishi Kobayashi