| 摘要 |
PROBLEM TO BE SOLVED: To obtain a base oil which is highly viscous and shows a high viscosity index and excellent thermal stability by using an aromatic polycarboxylate. SOLUTION: The aromatic polycarboxylate represented by the formula is used. The aromatic polycarboxylate is produced by esterification of an aromatic polycarboxylic acid such as phthalic acid, trimellitic acid, and pyromellitic acid and an alcohol having a hydrocarbon group represented by formula II and if necessary a conventional alcohol under an ordinal esterification condition. (R1 is H or-COOR<5> ; R<2> is H or-COOR<6> ; R<3> , R<4> , R<5> and R<6> are each a hydrocarbon (at least one of R<3> -R<6> is represented by formula II (R<7> and R<8> are each a hydrocarbon having not less than 4C; and n is an integer of not less than 1)); and R<7> and R<8> are each preferably an alkyl group having not less than 4C). A lubricant base oil may be mixed with other lubricant base oil but the amount of the other lubricant base oil is preferably not more than 80 wt.%. |
