| 摘要 |
PURPOSE:To obtain an impregnating pitch with excellent impregnation properties by centrifugally separating a raw pitch so as to leave quinoline-insolubles in such an amt. that the amt. of the quinoline insolubles in the pitch remaining after removal of a light oil fraction is in a specified range. CONSTITUTION:In preparing an impregnating pitch by subjecting a raw pitch to centrifugal separation to remove quinoline-insolubles and removing a light oil fraction from the treated liquid, the operation is carried out as follows. The quinoline-insolubles in the centrifugally treated liquid is allowed to remain in such as amt. that the amt. of the quinoline-insolubles after removal of a light oil fraction is 0.1-1.0%, by controlling conditions of the centrifugal separation and/or viscosity of the mother liquor for the centrifugal treatment. Said conditions of centrifugal separation mean centrifugal acceleration and the time of centrifugal separation, and the viscosity of the mother liquor is adjusted by a temp. and/or the amt. of a viscosity modifier added to the raw pitch. |
