PROCESS OIL AND HIGH-VISCOSITY BASE OIL AND THEIR PRODUCTION METHODS

摘要

PROBLEM TO BE SOLVED: To provide a novel and highly economical process for producing a process oil which is highly safe and exhibits good penetration into a rubber polymer and contains a DMSO extract lower than 3%. SOLUTION: In a process for producing an extract useful as a process oil and a raffinate useful as a high-viscosity base oil by solvent purification, vacuum distillation is conducted under such conditions that the end point of the distillate in terms of normal pressure is 580 deg.C or higher or under such conditions that the initial boiling point of the residue is 450 deg.C or higher; the resultant residual oil is deasphalted under such conditions as to give a deasphalted oil having a residual carbon content of 1.6% or lower; and the deasphalted oil is subjected to solvent purification under such conditions that the extract yield is 35-60%.