Tokai Carbon Company, Ltd.

Fumio Takemura

Toshio Nakada

Kazuhito Kataoka

Masao Ishiwata

Yoshihito Sema

Kiyonari Nakai

A carbon black of the category of hard carbon blacks having a nitrogen adsorption specific surface area (N.sub.2 SA) of 120 to 165 m.sup.2 /g and a DBP absorption number of 120 ml/100 g or more and satisfying requirements respectively represented by the following formulae (1) and (2):

Carbon black for tire tread rubber

A granular carbonaceous heat insulator comprising a carbon black pellet the surface of which is coated with a carbon layer having a dense structure is disclosed. This heat insulator is prepared by adhering a binder solution to a carbon black pellet, heating the resulting coating to remove a solvent from the binder solution and, at the same time, to cure the binder, and baking the carbon black pellet coated with the cured binder in a non-oxidizing atmosphere to carbonize the cured binder. Alternatively, the heat insulator is prepared by subjecting a carbon black pellet having specific characteristics to wet granulation in the presence of a binder solution to crush the carbon black pellet and, at the same time, to granulate the crushed pellet, thereby preparing a granulated carbon black pellet, followed by removal of the solvent from the prepared pellet, curing of the binder and baking of the cured binder in the same manner as that described above.

Carbonaceous granular heat insulator and process for preparing the same

Magnetic carbon black, a process for preparing the same, and a method of modifying magnetic carbon black are provided. The magnetic carbon black is prepared by process A in which when a hydrocarbon is supplied into a high temperature combustion gas stream formed by combustion of a fuel to prepare carbon black, an organic transition metal compound is supplied together with the hydrocarbon and, at the same time, an oxygen gas is supplied from the circumference of the hydrocarbon, process B in which a transition metal compound is supplied together with a hydrogen gas on the downstream side of the supply position of the hydrocarbon, and process C in which a hydrocarbon is supplied into a high temperature combustion gas stream on both the upstream side and the downstream side and a transition metal compound is supplied from a position between the supply positions of the hydrocarbon. The average particle diameter of the magnetic fine particle and the average particle diameter of carbon black in the magnetic carbon black prepared by process A are 30 nm or more and 20 nm or less, respectively. THe magnetic characteristics of the magnetic carbon black can be enhanced by heating the magnetic carbon black in a non-oxidizing atmosphere at 400.degree. to 900.degree. C.

Method of producing magnetic carbon black

Magnetic carbon black, a process for preparing the same, and a method of modifying magnetic carbon black are provided. The magnetic carbon black is prepared by process A in which when a hydrocarbon is supplied into a high temperature combustion gas stream formed by combustion of a fuel to prepare carbon black, an organic transition metal compound is supplied together with the hydrocarbon and, at the same time, an oxygen gas is supplied from the circumference of the hydrocarbon, process B in which a transition metal compound is supplied together with a hydrogen gas on the downstream side of the supply position of the hydrocarbon, and process C in which a hydrocarbon is supplied into a high temperature combustion gas stream on both the upstream side and the downstream side and a transition metal compound is supplied from a position between the supply positions of the hydrocarbon. The average particle diameter of the magnetic fine particle and the average particle diameter of carbon black in the magnetic carbon black prepared by process A are 30 nm or more and 20 nm or less, respectively. The magnetic characteristics of the magnetic carbon black can be enhanced by heating the magnetic carbon black in a non-oxidizing atmosphere at 400.degree. to 900.degree. C.

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Gotenba, Japan

Fumio Takemura