A grease composition including: a base oil; a thickener; a zinc sulfonate; a polysulfide; an overbased calcium sulfonate; and triphenyl phosphite, in which a proportion of the zinc sulfonate with respect to a total mass of the base oil and the thickener is 0.030 mass% to 0.045 mass% in terms of a zinc content, a proportion of the polysulfide with respect to the total mass of the base oil and the thickener is 0.16 mass% to 0.24 mass% in terms of a sulfur content, a proportion of the overbased calcium sulfonate with respect to the total mass of the base oil and the thickener is 0.010 mass% to 0.015 mass% in terms of a calcium content, and a proportion of the triphenyl phosphite with respect to the total mass of the base oil and the thickener is 0.24 mass% to 0.36 mass%.

A grease composition for a constant-velocity joint includes a mineral oil, a thickener, a molybdenum dithiocarbamate, a potassium borate hydrate, and a zinc dialkyldithiophosphate, wherein a content of the molybdenum dithiocarbamate is 1.2% by mass or more and 8% by mass or less, a content of the zinc dialkyldithiophosphate is 0.3% by mass or more and 2.0% by mass or less, and a content of the potassium borate hydrate is 0.28% by mass or more and 1.9% by mass or less, and wherein a mass ratio of the content of the molybdenum dithiocarbamate to the content of the potassium borate hydrate (molybdenum dithiocarbamate/potassium borate hydrate) is 2 or more and 13 or less, and a mass ratio of the content of the zinc dialkyldithiophosphate to the content of the potassium borate hydrate (zinc dialkyldithiophosphate/potassium borate hydrate) is 0.5 or more and 3.6 or less.

A method for producing a raw material of grease, including: preparing first thickener raw material; second thickener raw material; first lubricating oil; second lubricating oil; first solvent with a boiling point lower than those of the oils, dissolves the first oil, and does not dissolve a produced thickener; and a second solvent with a boiling point lower than those of the oils, dissolves the second oil, and does not dissolve the produced thickener; dissolving the first lubricating oil in the first solvent, and dissolving or dispersing the first thickener raw material in the first solvent to obtain a first mixed solution; dissolving the second lubricating oil in the second solvent, and dissolving or dispersing the second thickener raw material in the second solvent to obtain a second mixed solution; and mixing the first and second mixed solutions, and reacting the first and second thickener raw materials producing a thickener.

A method of making a urea containing powder by injecting an amine and an isocyanate simultaneously into a mixing chamber is disclosed. The method comprises mixing in a high-pressure impingement mixing device at a pressure of at least 2500 psi for a time less than 10 seconds. The resulting urea containing powders have defined particle sizes and molecular weight distributions as well as a stoichiometric mole ratio of isocyanates and amine functionalities. Methods of making a thickened polyurea containing master batch with the urea containing powders using a shear thickening step, and making a grease by gelling the first or second urea containing powder under heat and in the presence of an oil are also disclosed.

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 μm 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.

The grease composition including: a base oil having a kinematic viscosity of 5 to 30 mm.sup.2/s at 100° C., a thickener, a polymer having a weight average molecular weight of 1,000 to 500,000, and an aliphatic amide compound. The grease composition is used for sliding between a metal member and a resin member, and capable of reducing friction between them.

The present invention relates to provision of an extreme pressure agent-containing grease composition using, as a thickener, a urea-based thickener, the grease composition being excellent in both torque transmitting efficiency and leakage prevention performance and also excellent in wear resistance and load resistance. The grease composition contains a base oil (A), a urea-based thickener (B), and an extreme pressure agent (C), wherein particles containing the urea-based thickener (B) in the grease composition satisfies the following requirement (I): Requirement (I): an arithmetic average particle diameter of the particles on an area basis as measured by the laser diffraction/scattering method is 2.0 μm or less, and the extreme pressure agent (C) is at least one selected from an organic metal-based extreme pressure agent, a sulfur-based extreme pressure agent, a phosphorus-based extreme pressure agent, and a sulfur-phosphorus-based extreme pressure agent.

A lubricant grease composition is disclosed, the lubricant grease composition including a base oil and a thickener. The thickener includes an aluminum-based complex soap and a polyurea thickener, wherein the lubricant grease is configured for lubrication of surfaces of components in which an upper use temperature of the lubricant grease composition is at least 90° C.

Provided is a rolling bearing using a retainer, particularly a highly reliable retainer in which dimensional stability required for a retainer of an outer ring guide type, ductility required for a crown-type retainer, improvement in adhesion of grease with a poly-α-olefin oil or the like as a base oil, and deformation prevention at a high speed can be achieved. The rolling bearing includes at least an inner ring 1, an outer ring 3, a synthetic resin retainer 9, and a rolling element 7, in which the synthetic resin retainer 9 is formed of a polyamide resin composition including polyamide 410 and a reinforcing fiber material with a content of 0% by weight to 40% by weight.

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.