Jx Nippon Oil Energy Corporation

Hiroya Miyamoto

Shigeki Matsui

Akira Yaguchi

Kazuo Tagawa

Akira Takagi

Ryuichi Ueno

Teppei Tsujimoto

Hiromitsu Matsuda

Reiko Kudo

The present invention provides a poly(meth)acrylate-based viscosity index improver comprising a core portion and three or more arm portions, wherein each of the arm portions consists of a polymer chain comprising a structural unit represented by the following formula (1), and one end of the polymer chain is bonded to the core portion, and wherein a weight-average molecular weight Mw is 100000 or more, and a ratio of the weight-average molecular weight Mw to a number average molecular weight Mn, Mw/Mn, is 1.6 or less.  [Rrepresents hydrogen or a methyl group, and Rrepresents a C1 to C36 alkyl group.]

Poly(meth)acrylate-based viscosity index improver, lubricant additive and lubricant composition containing viscosity index improver

The present invention provides a lubricating oil composition for an internal combustion engine used mainly to drive a generator and to improve the fuel economy thereof. The composition comprises (A) a base oil being a hydrocarbon base oil having a ratio (CA/CB) of the proportion of the component of 24 or fewer carbon atoms (CA) and the proportion of the component of 25 or more carbon atoms (CB) in the carbon number distribution obtained by gas chromatography distillation of 2.0 or higher, the composition having a ratio (Vs/Vk) of the 80&#xb0; C. high-temperature high-shear (HTHS) viscosity (Vk) and the 150&#xb0; C. HTHS viscosity (Vs) of 0.35 or higher and a 100&#xb0; C. kinematic viscosity of 2.5 mm/s or higher and 5.2 mm/s or lower.

Lubricating oil composition

The present invention provides a lubricating oil composition for an internal combustion engine used mainly to drive a generator and to improve the fuel economy thereof. The composition comprises (A) a base oil being a hydrocarbon base oil having a ratio (CA/CB) of the proportion of the component of 24 or fewer carbon atoms (CA) and the proportion of the component of 25 or more carbon atoms (CB) in the carbon number distribution obtained by gas chromatography distillation of 2.0 or higher, the composition having a ratio (Vs/Vk) of the 80&#xb0; C. high-temperature high-shear (HTHS) viscosity (Vk) and the 150&#xb0; C. HTHS viscosity (Vs) of 0.4 or higher and a 100&#xb0; C. kinematic viscosity of 5.2 mm/s or higher and 8 mm/s or lower.

The lubricating oil composition of the invention comprises a lubricating base oil with a kinematic viscosity at 100&#xb0; C. of 1-20 mm/s, and a viscosity index improver having a ratio M/Mof 0.20 or greater, between the total area of the peaks between chemical shifts of 36-38 ppm Mand the total area of the peaks between chemical shifts of 64-66 ppm M, with respect to the total area of all of the peaks, in the spectrum obtained byC-NMR. The lubricating oil composition of the invention has excellent effects, with a sufficiently high HTHS viscosity at 150&#xb0; C., and a sufficiently low kinematic viscosity at 40&#xb0; C., a sufficiently low kinematic viscosity at 100&#xb0; C. and a sufficiently low HTHS viscosity at 100&#xb0; C.

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Tokyo, Japan

Hiroya Miyamoto