Biodegradable lubricating oil composition

Abstract

[PROBLEMS] To provide a biodegradable lubricating oil composition which has excellent biodegradability, a high viscosity index, a low pour point, a high flash point, being satisfactory with lubricity, oxidative stability, property of preventing the corrosion of iron and non-ferrous metals, and suitability for use with sealing materials.[MEANS FOR SOLVING THE PROBLEMS] A biodegradable lubricating oil composition comprising (A) a synthetic ester base oil comprising at least 50 mass % hindered ester of an aliphatic monocarboxylic acid with an aliphatic hindered polyol which has one or more quaternary carbon atoms per molecule and in which at least one of the quaternary carbon atoms has one to four methylol groups bonded thereto and (B) ingredients which are (a) 0.1 to 5.0 mass % phenolic antioxidant, (b) 0.01 to 2.0 mass % calcium sulfonate having a low base number, and (c) 0.01 to 1.0 mass % triazole compound, and has the degree of biodegradation of 60% or higher when examined by the test for the degree of microbial degradation of chemical substances according to the OECD Test Guideline 301C method.

Description

CROSS REFERENCE TO RELATED APPLICATIONS[0001]This application is a continuation application of prior U.S. application Ser. No. 10 / 585,203, filed Jul. 3, 2006, the disclosure of which is incorporated herein by reference in its entirety. The parent application is the National Stage of PCT / JP05 / 01216, filed Jan. 28, 2005, the disclosure of which is incorporated herein by reference in its entirety. The parent application claims priority to Japanese Application No. 2004-024291, filed Jan. 30, 2004, the disclosure of which is incorporated herein by reference in its entirety.TECHNICAL FIELD[0002]The present invention relates to a biodegradable lubricating oil composition. More specifically, it relates to a synthetic ester-based biodegradable lubricating oil composition which has excellent biodegradability, a high viscosity index, a low pour point, a high flash point, being satisfactory with lubricity, oxidative stability, property of preventing the corrosion of iron and non-ferrous metals,...

AI Technical Summary

Benefits of technology

[0096]The biodegradable lubricating oil composition of the present invention comprises a synthetic ester base oil having excellent biodegradability, has well-balanced properties including lubricating performance, and is preferably used, for example, as a hydraulic fluid, automotive lubricating oil, metal-working oil, and so on.

Problems solved by technology

However, biodegradable lubricating oils have not widely been used in Japan because of their higher cost compared with conventional mineral oil-based lubricating oils, in spite of high attention.

However, vegetable oils have a problem of thermal or oxidative instability as well as unstable supply despite low cost, and polyalkyleneglycols have a problem of a poor suitability for use with sealing materials despite low cost and good thermal stability.

Therefore, although synthetic esters are becoming more popular as biodegradable lubricating oils in Japan, they still have a substantial weakness against a mineral oil-based lubricating oil in terms of the cost and oxidative stability.

Although the above-mentioned biodegradable lubricating oils are satisfactory with respect to lubricity and oxidative stability, they still have problems of a high pour point, substantial metal dissolution of non-ferrous metals used for materials for hydraulic machinery, extreme swelling of sealing materials, and so on.Patent Document 1: JP Kokai 1993-339591Patent Document 2: JP Kokai 1994-228579Patent Document 3: JP Kokai 1997-249889Patent Document 4: JP kokai 1999-323373

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