Idemitsu Kosan Company, Limited

Thk Co., Ltd.

Kouji Takane

Go Watanabe

Yukitoshi Fujinami

Hiroki Sekiguchi

Yoshiyuki Suetsugu

Yusuke Nakanishi

Keisuke Inda

Akihiro Shishikura

Tsukasa Yamagishi

Akira Nogami

Terumoto Hayami

Hiroshi Sampei

Jun Yamashita

A grease composition, containing a base oil (A), a urea-based thickener (B), and a polymer compound (C). The particles that make up the urea-based thickener (B) in the grease composition satisfy the following requirement (I): the particles have an arithmetic average particle diameter on an area basis as measured by a laser diffraction/scattering method of 2.0 μm or less, and the polymer compound (C) has a number average molecular weight (Mn) of 30,000 or more and a molecular weight distribution (Mw/Mn) of 2.20 or less.

Grease composition

A grease composition, containing a base oil (A), a urea-based thickener (B), and melamine cyanurate (C). Particles containing the urea-based thickener (B) in the grease composition satisfy the following requirement (I): the particles have an area-based arithmetic average particle diameter of 2.0 μm or less, as measured by a laser diffraction/scattering method.

The present invention relates to a grease composition which can impart excellent durability to a bearing used under a high-speed rotation condition with a DN value of 100,000 or more, wherein the grease composition contains a base oil (A) and a urea-based thickener (B), and particles containing the urea-based thickener (B) in the grease composition satisfy requirement (I) that the particles have an arithmetic mean particle diameter of 2.0 &#x3bc;m or less on an area basis when measured by a laser diffraction scattering method. The grease composition is used for a bearing used under a high-speed rotation condition with a DN value of 100,000 or more.

A grease of the invention contains a fluorine synthetic oil as a base oil and an inorganic acid salt that is at least one selected from phosphate, tungstate, sulfate and sulfite. The grease of the invention is suitably usable in a bearing, a gear and the like because of an excellent wear resistance and a low environmental burden.

Grease

A grease composition contains a calcium sulfonate complex grease and an additive. The additive includes an overbased metal sulfonate and an antioxidant. The overbased metal sulfonate is preferably an overbased calcium sulfonate. The antioxidant is preferably an aminic antioxidant.

A bearing grease composition contains a (A) thickener and a (B) base oil, in which the (A) thickener is a urea thickener represented by a formula (I) below, and, in observation of a transmission image in the bearing grease composition, a transmission-image-area ratio of an aggregation part having a transmission image area exceeding 40 &#x3bc;min the urea thickener is 15% or less relative to a total observation area.RNHCONHRNHCONHR&#x2003;&#x2003;(I) In the formula, Rand Reach independently represent: an (a1) monovalent chain hydrocarbon group having 6 to 22 carbon atoms; an (a2) monovalent alicyclic hydrocarbon group having 6 to 12 carbon atoms; and the like, and Rrepresents an (a4) divalent aromatic hydrocarbon group having 6 to 15 carbon atoms.

Grease composition for bearing

A urea grease of the invention is prepared by applying shear at a shear rate of 10sor more to a mixture solution of an amine mixture containing an alicyclic monoamine and a chain aliphatic monoamine, and a diisocyanate compound to cause a reaction in the mixture, in which the urea grease has Peak High32-64s of 1.5 or less and Level High32-64s of 10 or less according to an FAG method.

Urea grease

The grease composition for a clean environment includes, a base oil, a thickener and a extreme-pressure agent, in which a kinetic viscosity of the base oil at 40&#xb0; C. is 100&#x2dc;300 mm/s, the thickener comprising a lithium complex soap, a content of the thickener is 10&#x2dc;40 mass % with respect to the total amount of the grease composition.

Growing community of inventors

Ichihara, Japan

Kouji Takane