| 摘要 |
PROBLEM TO BE SOLVED: To obtain an inexpensive biodegradable lubricating oil, excellent in biodegradability and having good fluidity, lubricating property and stability to oxidation by including an aromatic polycarboxylic acid-based ester having a specified structure. SOLUTION: This lubricating oil comprises one or two or more kinds of aromatic carboxylic acid-based esters obtained by each using (A) one or two or more kinds of compounds [preferably (anhydrous) phthalic acid] selected from the group comprising an aromatic polycarboxylic acid represented by the formula [(n) is 2-4] and its anhydride as an acid component and (B) one or two or more monohydric alcohols selected from a group comprising a 1-18C aliphatic straight-chain saturated alcohol, a 2-18C aliphatic straight-chain unsaturated alcohol, a 3-18C aliphatic branched chain saturated alcohol and a 3-10C alicyclic saturated alcohol (preferably n-pentanol, etc., in an amount of >=50 equivalent % based on total alcohol component and (C) one or two or more kinds of 2-18C polyhydric alcohols (preferably ethylene glycol) as alcohol components. |
