Abstract: A pitch which affords a carbon fiber having a high strength and a high elastic modulus is obtained by treating a pitch containing 5 to 35 weight percent of an optically anisotropic region with sulfur.

Abstract: A pitch which affords a carbon fiber having a high strength and a high elastic modulus is obtained by treating a pitch containing 5 to 35 wt. % of an optically anisotropic region with an oxidizing gas, followed by hydrogenation treatment if required.

Abstract: A process for the production of carbon fibers which comprises using a specific optically isotropic pitch having a reflectivity of 9.0-11.0% as the material for the carbon fibers.

Abstract: A process for the production of high performance carbon fibers which comprises using as the starting material a specific pitch having the lowest reflectivity in the range of 8.5-9.3% and the highest reflectivity in the range of 11.8-12.5%.

Abstract: A process for the production of carbon fibers comprising heat treating a starting material, melt spinning the resulting precursor pitch, infusibilizing the pitch fibers and carbonizing or graphitizing the infusibilized pitch fibers, characterized in that the starting pitch is obtained by heat treating coal tar and/or coal liquefaction pitch at a specific temperature and a specific hydrogen pressure or by mixing coal tar and/or coal liquefaction tar with at least one nucleus-hydrogenated hydrocarbon of 2-3 rings in a specific mixing ratio and then heat treating the resulting mixture at a specific temperature and a specific pressure. In one embodiment, this invention relates to the starting pitch and carbon fibers obtained by said process.

Abstract: A starting pitch for carbon fibers, obtained by mixing (1) a heavy fraction oil boiling at not lower than 200.degree. C. obtained at the time of steam cracking of petroleum with (2) wax and then heat treating the resulting mixture at a specified temperature and pressure thereby to obtain the starting pitch, the thus obtained starting pitch being heat treated to produce a precursor pitch which is melt spun, infusibilized, carbonized or graphitized to obtain the carbon fibers.

Abstract: A starting pitch for carbon fibers, obtained by (A) mixing (1) a heavy fraction oil boiling at not lower than 200.degree. C. obtained at the time of steam cracking of petroleum with (2) a hydrogenated oil selected from aromatic hydrocarbons of 2-10 rings in which the nuclei have been hydrogenated and specific fractions boiling at 160.degree.-650.degree. C. and containing such nuclei-hydrogenated hydrocarbons and then (B) heat treating the resulting mixed oil at 370.degree.-480.degree. C. and 2-50 Kg/cm.sup.2.G to obtain the starting pitch for carbon fibers.

Abstract: A starting pitch for carbon fibers, produced by heat treating at 400.degree.-500.degree. C. under a hydrogen pressure of at least 20 Kg/cm.sup.2.G (1) a heavy fraction oil boiling at not lower than 200.degree. C. obtained at the time of fluidized catalytic cracking of petroleum or (3) a mixture of the heavy fraction oil (1) with (2) a heavy fraction oil boiling at not lower than 200.degree. C. obtained at the time of steam cracking of petroleum, the pitch so produced being heat treated to make precursor pitch therein, melt spun, infusibilized and carbonized or further graphitized to obtain the carbon fibers.

Abstract: A tap hole mix for blocking the pig iron or steel tap hole of furnaces, comprising refractory material and a binder comprising a petroleum-derived heavy oil having at least 25% Conradson carbon and an aromatic petroleum resin.

Abstract: A process for the preparation of petroleum-derived binder pitch, comprising heat treating a mixture of both (1) a heavy fraction boiling at not lower than 200.degree. C. and being obtained by the steam cracking of petroleum such as naphtha and (2) a heavy fraction boiling at not lower than 200.degree. C. and being obtained by the catalytic cracking of petroleum such as gas oil.

Abstract: A method for producing refractories which comprises the steps: continuously feeding as a raw material a heavy oil having a boiling point higher than 150.degree. C. obtained by thermal cracking or steam cracking of petroleum hydrocarbons in a first state stirring vessel maintained at a pressure of higher than 2 Kg/cm.sup.2 G and a temperature within the range of from 300.degree. to 360.degree. C.; maintaining said raw material oil at an average residence time of longer than 15 minutes; continuously withdrawing a first stage treated oil from said first stage stirring vessel; supplying said first stage treated oil in a second stage stirring vessel maintained at a temperature within the range of from 370.degree. to 450.degree. C.

Abstract: An amorphous refractory composition comprising a petroleum-derived binder prepared by feeding a fraction boiling at not lower than 150.degree. C. obtained by thermal or steam cracking of petroleum-derived hydrocarbons, into a first-step agitating vessel where the fraction is heat treated under specific conditions, feeding the thus heat treated fraction into a second-step agitating vessel where it is heat treated under specific conditions and then removing the light fraction from the further heat treated fraction thereby to obtain the petroleum-derived binder.

Abstract: A process for the continuous production of petroleum-derived pitch comprising the steps of subjecting a heavy fraction boiling at not lower than 150.degree. C., the heavy fraction being obtained by the steam cracking of petroleum-derived hydrocarbons, to a specified first-step heat treatment, subjecting the first-step treated fraction to a specified second-step heat treatment and then removing the light fraction from the second-step treated fraction thereby to obtain the petroleum-derived pitch.

Abstract: A process for producing unburned basic refractories wherein a binder is added and kneaded with a basic refractory material and the kneaded mixture is press-formed. The binder is a thermoplastic resinous material which is obtained by removing a light fraction having a boiling point of less than 200.degree. C under a reduced pressure of 100 mmHg and having a benzene-insoluble fraction content of less than 10% by weight from at least one member selected from the group consisting of a heavy oil obtained by a steam cracking of petroleum and a polymerization product of said heavy oil. The slag penetration resistance, slag erosion resistance and slaking resistance of the given unburned basic refractories are substantially improved.