Lubricating oil composition

Abstract

A lubricant composition is disclosed which can largely reduce abrasion, can exhibit a low friction coefficient steadily, and has a high corrosion resistance in the lubrication of an iron-based sliding member. The lubricant composition includes a lubricant base oil, a 3,4,5-trihydroxybenzoic acid ester in an amount of 0.01 to 10 mass % relative to the total amount of the lubricant composition, and a detergent dispersant in an amount of 0.1 to 20 mass % relative to the total amount of the lubricant composition.

Description

TECHNICAL FIELD[0001]The present invention relates to a lubricating oil composition. In particular, the invention relates to a lubricating oil composition that is used as a lubricating oil for an internal combustion engine, as a lubricating oil for a driving system, or as a hydraulic oil.BACKGROUND ART[0002]In recent years, reduction in environmental load has become desirable in various fields. In particular, reduction of carbon dioxide (CO2) emission is a task of pressing urgency, and efforts to conserve energy have been made in various domestic industries and transport industries including automobile transportation, as well as in general public consumption.[0003]For example, in the automotive industry, the efficiency of gasoline engine has been improved by adopting lean-burn technology, direct-injection technology or the like in order to improve on fuel consumption and to reduce CO2 emissions. On the other hand, use of a low-friction material for sliding members, or adoption of fu...

AI Technical Summary

Benefits of technology

[0019]Since the lubricating oil composition according to the invention comprises a lubricating oil base oil, a 3,4,5-trihydroxybenzoic acid ester, and a detergent dispersant, it significantly reduces wear, stably exhibits low friction coefficient, and has an excellent rust prevention effect on iron sliding members. Therefore, the lubricating oil composition of the invention can be suitable for a long-term use, and exhibit a significant effect for energy conservation due to the low and stable friction coefficient.MODES FOR CARRYING OUT THE INVENTION

[0020]A lubricating oil composition according to the invention contains a 3,4,5-trihydroxybenzoic acid ester in an amount of 0.01 to 10 mass %, and a detergent dispersant in an amount of 0.1 to 20 mass %, in addition to a lubricating oil base oil. Since a 3,4,5-trihydroxybenzoic acid ester exhibits low solubility in a mineral base oil or in a hydrocarbon base oil not containing a polar group such as ester, ether or the like, the 3,4,5-trihydroxybenzoic acid ester alone cannot be added to the effective concentration at which the improved lubricity is achieved. However, the 3,4,5-trihydroxybenzoic acid ester can be used at the effective concentration at which the improved lubricity is achieved if it is used in combination with a detergent dispersant.Lubricating Oil Base Oil

[0021]Mineral oil, synthetic oil, animal / plant oil, or the like may be used as the lubricating oil base oil in the invention. Two or more of these lubricating oil base oils may also be used in combination.

[0022]The physical properties of the lubricating oil base oil used in the lubricating oil composition according to the invention are not particularly limited, but it is preferable that the lubricating oil base oil has a kinematic viscosity at 40° C. of 5 to 1000 mm2 / s, more preferably 5 to 500 mm2 / s, and still more preferably 5 to 100 mm2 / s, because the energy conservation can be facilitated by reducing the viscosity. However, it should be noted that, for high-load applications, it is preferable to use a base oil having high viscosity.

[0023]The viscosity index of the lubricating oil base oil is preferably 90 or higher, and more preferably 100 to 250. The pour point, which is a low-temperature property, of the lubricating oil base oil is preferably −10° C. or lower, and more preferably −15° C. or lower. Moreover, from the viewpoint of safety, the flash point of the lubricating oil base oil is preferably 70° C. or higher, and more preferably 150° C. or higher.

[0024]The lubricating oil base oil is preferably used in an amount of 70 to 99 mass % relative to the total amount of the lubricating oil composition, and more preferably 80 to 98 mass %.

Problems solved by technology

However, a reduction of phosphorus content in the lubricating oil could cause the problem of poor wear resistance, seizure, or the like.

However, a decrease in wear resistance of sliding members, seizure of sliding members, and so on, have been the problems associated with the lower viscosity.

Ideal characteristics of a lubricating oil is that friction losses are small at high speed as well as at low speed, and that wear such as fretting wear or the like is small.

However, wear due to fretting may easily occur when the viscosity of the lubricating oil base oil is reduced; that is, base metals of the sliding members could come into contact with each other, causing wear or seizure.