Director-general of the Agency of Industrial Science and Technology

Director-general of Agency of Industrial Science and Technology

Agency of Industrial Science and Technology

Tanaka Kikinzoku Kogyo K.k.

Maruzen Petrochemical Company, Limited

Koa Oil Company, Limited

Koa Oil Company, Limited Director General, Agency of Industrial Science

Itaru Todorok, Director-general of Agency of Industrial Science and

Yasuhiro Yamada

Hidemasa Honda

Takeshi Imamura

Hitoo Kakiyama

Masaki Fujii

Toru Sawaki

Susumu Shimizu

Masatoshi Tsuchitani

Ryoichi Nakajima

Hideharu Sasaki

Haruki Yamasaki

Masanori Minohata

Masao Shibata

Masanao Nakagawa

Seiji Arita

Seiji Shimomura

Disclosed herein is curled or uncurled composite carbon fiber which comprises part of optically isotropic carbon fiber and balance of optically anisotropic one and a process for preparing the same. The composite carbon fiber possesses the excellent characteristics by complementing the respective defects by means of the respective characteristics of the both kinds of the carbon fiber.

Composite carbon fiber and process for preparing same

A method for producing an elastic graphite material having a packing density of 1.0 g/cm.sup.3 or lower and a recovery of 50% or higher at a compressibility of 10 to 90% is provided, which comprises: heating a carbonaceous material rapidly while bringing the carbonaceous material into contact with nitric acid for expansion and foaming, and graphitizing the thus expanded and foamed carbonaceous material.

Preparation of elastic graphite materials

A graphite structure, which is of light weight and excellent elasticity and has a packing density of 0.5 g/cm.sup.3 or lower and a recovery of 50% or higher at a compressibility of 10 to 90%, is obtained by treating a carbonaceous material with nitric acid or a mixture of nitric and sulfuric acids and, then, heat-treating the obtained product at a temperature of 2,400.degree. C. or higher to graphitize the same.

Graphite structures and method for production thereof

When preparing carbon fibers from mesophase pitches, we usually encounter to the formation of cracks along the fiber axis. The crack formation is the most serious and troublesome problem. A simple process which can effectively prevent the crack formation comprises preparing the carbon fibers from mesophase pitches by melt spinning sufficient only to give a rotatory motion to the molten mesophase pitches just before extrusion substantially around the axis of a spinning nozzle hole. The process employs a usual nozzle plate having a pitch introducing tube and a spinning nozzle hole further containing a plug member having an outer spiral groove such as a drill point or a worm gear which is inserted within the pitch introducing tube.

Process to prevent crack formation in the production of carbon fibers

The invention provides a method for the preparation of a pitch spinnable into pitch filaments as a precursor of carbon fibers starting from a pitch material such as coal tar and coal tar pitch. Different from the conventional procedure involving hydrogenation of the starting pitch, the starting pitch in the inventive method is first heated together with an aromatic oil, preferably, in the presence of a cracking catalyst such as silica-alumina and zeolite at 350.degree. to 500.degree. C. for 10 to 60 minutes under no pressurization with hydrogen and, after removal of insoluble materials, then heated at a temperature of 430.degree. to 600.degree. C. The thus obtained pitch for spinning has good spinnability and the carbon fibers prepared from the pitch have a unique microscopic structure and excellent physical properties exceeding by far the conventional pitch-based carbon fibers and approximating the HP-grade carbon fibers prepared from polyacrylonitrile fibers.

Method for the preparation of pitches for spinning carbon fibers

The invention provides carbon fibers having mechanical properties equival to or even better than those of the polyacrylonitrile-based carbon fibers from a bituminous material, e.g. coal tar pitch, as the starting material. The starting pitch is first partially hydrogenated in tetrahydroquinoline under specific conditions followed by a heat treatment to give a pitch composition suitable for spinning which can be characterized by several parameters including the proportions of the carbons and hydrogens having different chemical shifts in the NMR analysis. The pitch composition for spinning is then subjected to spinning under specific conditions including the temperature condition for controlling the viscosity behavior of the molten pitch composition determined by use of the Andrade's equation and the pitch filament is then infusibilized in an oxidative atmosphere and carbonized in an inert atmosphere into carbon fibers having a tensile strength of at least 200 kg/mm.sup.2 and a tensile modulus of at least 10 tons/mm.sup.2.

Pitch-based carbon fibers and pitch compositions and precursor fibers

An ashless liquid fuel of good quality is produced by mixing powdery coal with a pitch having a C/H ratio of from 0.90 to 1.20 in an amount of at least 50 parts by weight per 100 parts by weight of the powdery coal, subjecting the mixture to a heat treatment conducted at from 400.degree. to 450.degree. C. and thereafter, removing a solid coagulated material formed in the treated product. The pitch having an atomic ratio C/H in the range from 0.90 to 1.20 is obtained by the heat treatment of a residual oil in the distillation of crude oils.

Process for the production of ashless liquid fuels

A process for liquefying coal to produce liquid fuel and pitch-like substes suitable as starting materials for various carbonaceous materials, which process comprises incorporating powdery coal with a heavy oil of petroleum series having a high carbon content of at least 0.9 in terms of the atomic ratio C/H in an amount of at least 50 parts by weight per 100 parts of the powdery coal, subjecting the mixture to a heat treatment conducted at 320.degree.-400.degree. C for 0.5-10 hours thereby liquefying the coal.

Process for liquefying coal

Micro-beads having a carbonaceous structure are produced by a process comsing heating pitch at about 350-500.degree.C to form optically anisotropic spherules, extracting the resulting spherules with an organic solvent to remove substantially all remaining pitch therefrom, and then carbonizing the pitch-free spherules in a non-oxidizing atmosphere. The optically anisotropic micro-beads substantially free of pitch can be shaped to a desired form and then carbonized to produce a shaped carbonaceous structure. If the carbonizing temperature is above about 1500.degree.C, a graphite crystalline structure results.

Growing community of inventors

Tosu, Japan

Yasuhiro Yamada