Abstract: A pitch is disclosed which is used as a raw material for making carbon fibers. The pitch has a quinoline insoluble content of 7-18% by weight and a toluene insoluble content of 70-90% by weight. Further, the pitch preferably has a n-heptane soluble content of 1.0% by weight or less. A process for producing the pitch is also disclosed. The process comprises carrying out thermal modification of a petroleum heavy residual oil having a boiling point of 400.degree. C. or more (atmospheric pressure) and a sulfur content of 1.5% by weight or less. Insoluble substances are then separated and removed by heating at a temperature of 380.degree. C. or less. Thereafter, a low boiling point fraction is removed by vacuum distillation. The pitch can be utilized to producd carbon fibers without breaking of filaments in spinning or adhesion by fusion of the fibers in infusibilization. The carbon fibers produced have a high tensile strength and high modulus of elasticity.

Abstract: A process for producing a pitch is disclosed. The process involves distilling a heavy petroleum oil under reduced pressure to obtain a distillate, the distillate is hydrogenated to obtain a hydrogenated oil which is subjected to catalytic cracking. The cracked oil is subjected to distillation to obtain a high boiling point fraction having a boiling point of more than 300.degree. C. The high boiling point fraction is subjected to thermal modification in order to obtain the pitch. The pitch can be utilized in order to produce carbon fibers of high quality. By utilizing the process a greater variety of starting materials can be utilized in order to produce the pitch which is utilized to produce high quality carbon fibers.

Abstract: A process for producing a pitch which can be utilized as a raw material for producing carbon fibers is disclosed. The process involves distilling a petroleum heavy residual oil under reduced pressure to produce a reduced pressure distillation residual oil or a reduced pressure distillate oil. The distillation residual oil is subjected to a solvent deasphaltening treatment to produce a solvent deasphaltened oil. The solvent deasphaltened oil or the reduced pressure distillate oil is subjected to solvent extraction to obtain a solvent extraction component. The solvent extraction component is thermally modified to produce the pitch. The pitch can be utilized in a melt-spinning process in order to produce carbon fibers having desirable characteristics.

Abstract: A process for producing a pitch used as a raw material for producing carbon fibers is disclosed. The process comprises the steps of carrying out catalytic cracking of a hydrogenated residual oil prepared by hydrogenation treatment of a petroleum heavy residual oil or a mixture composed of said hydrogenated residual oil and a hydrogenated distillate oil which is prepared by hydrogenation treatment of a reduced pressure distillate oil prepared by reduced pressure distillation of the petroleum heavy residual oil. The resulting cracking oil is then distilled to produce a high boiling point fraction having a boiling point of 300.degree. C. or more. The fraction is then subjected to thermal modification. The pitch is then utilized to produce carbon fibers which have desirable characteristics. The process is advantageous in that it makes possible the use of a wide variety of different types of oils in order to produce a pitch which can be utilized in producing carbon fibers having desirable characteristics.

Abstract: A process for producing a pitch which is used as a raw material for producing carbon fibers is disclosed. The process comprises subjecting a petroleum heavy residual oil to hydrogenation treatment in the presence of catalysts, removing a low boiling point fraction of the oil by reduced pressure distillation, subjecting the resulting reduced pressure distillation residual oil to solvent extraction treatment, and carrying out thermal modification of the resulting extraction component.By utilizing the process for producing the pitch it is possible to use a wide variety of different types of oils in order to produce carbon fibers. The carbon fibers produced from the pitch produced according to the disclosed process have desirable characteristics.