A urea grease of the invention is prepared by applying shear at a shear rate of 10.sup.2 s.sup.−1 or 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.

A lubricating grease composition, and more specifically, to a lubricating grease composition which, when used with an article clamping device, such as a chuck, produces excellent lubricating properties whilst remaining strongly adhered to metal parts in the clamping mechanism of the device and showing enhanced chemical and physical resistance to fluids such as cutting fluids with which they come into contact.

Provided is a grease composition including a base oil (A) containing an alkyl naphthalene (A1) and an aliphatic diurea (B) represented by general formula (b1):
R.sup.1—NHCONH—R.sup.3—NHCONH—R.sup.2  (b1) (wherein, R.sup.1 and R.sup.2 each independently represent a monovalent aliphatic hydrocarbon group having 9 to 20 carbon atoms, and R.sup.3 represents a divalent aromatic hydrocarbon group having 6 to 18 carbon atoms), wherein a content of the aliphatic diurea (B) is 20 to 30% by mass based on a total amount of the grease composition.

To provide a grease composition for a tapered roller bearing having superior bearing lifetime under a condition of high temperature and a condition of high load, and a tapered roller bearing in which the grease composition for the tapered roller bearing is filled. A tapered roller bearing 11 includes an inner ring 12 having a raceway surface 12a, an outer ring 13 having a raceway surface 13a and a plurality of tapered rollers 14, and a flange part of the inner ring 12 gets into sliding contact with the tapered rollers 14. Grease 16 is filled around the tapered rollers 14. The grease 16 includes a base oil, a thickener and an additive. A frequency in which a storage modulus, which varies depending on frequency, of the grease 16 becomes minimum is equal to 7 Hz or more.

The invention relates to lubricating greases based on alkali metal soaps and/or earth-alkali metal soaps and metal complex soaps based on (R)-10-hydroxyoctadecanoic acid and to the use thereof.

A continuous process for producing a polyurea concentrate or powder. The process includes combing at least one amine and an isocyanate in the presence of a liquid diluent or a base oil in a rotor stator mixer. The concentrate comprises a polyurea in a base oil wherein the concentration of from about 20 weight percent to about 50, or 40 or 35 or 30 weight percent of polyurea based on total weight of grease thickener. The powder has particle size of 2 to 400 microns. This concentrate or powder can then be formulated by grease manufacturers to the desired final properties without the need for handling of the isocyanate and amine raw materials.

A grease composition may be used for speed reducers and speed increasers, being excellent in both torque transmission efficiency and leak prevention performance. The grease composition may contain a base oil (A) and a urea-based thickener (B), which is used for speed reducers and speed increasers, wherein the particles containing the urea-based thickener (B) in the grease composition satisfy the following requirement (I). Requirement (I): the area-based arithmetic average particle diameter of the particles is 2.0 μm or less, as measured by a laser diffraction/scattering method.

A grease composition may be used for speed reducers and speed increasers, being excellent in both torque transmission efficiency and leak prevention performance. The grease composition may contain a base oil (A) and a urea-based thickener (B), which is used for speed reducers and speed increasers, wherein the particles containing the urea-based thickener (B) in the grease composition satisfy the following requirement (I). Requirement (I): the area-based arithmetic average particle diameter of the particles is 2.0 μm or less, as measured by a laser diffraction/scattering method.

The present invention relates to a grease composition including: a base oil; a thickener; a rust inhibitor; and an extreme pressure agent, in which the rust inhibitor includes, with respect to a total mass of the grease composition: 0.10 mass % to 10.00 mass % of a calcium sulfonate; 0.20 mass % to 10.00 mass % of a zinc sulfonate; and 0.10 mass % to 10.00 mass % of a zinc carboxylate, and the extreme pressure agent includes, with respect to the total mass of the grease composition, 2.00 mass % to 14.00 mass % of a zinc dialkyldithiophosphate.

The present invention addresses a problem of providing a grease composition containing a urea-based thickener and capable of appropriately maintaining the kinematic friction force in lubrication parts. The grease composition contains a base oil (A) and a urea-based thickener (B), wherein the base oil (A) has a kinematic viscosity at 40° C. of 100 mm.sup.2/s or more, and the particles containing the urea-based thickener (B) in the grease composition satisfy the following requirement (I). Requirement (I): the area-based arithmetic average particle diameter of the particles is 2.0 μm or less, as measured by a laser diffraction/scattering method.