The invention discloses a lubricating grease with thixotropy and a preparation method thereof. The lubricating grease comprises a polyurea/high base number calcium sulfonate composite thickener, colloidally dispersed calcium carbonate solid particles in the form of calcite, a calcium borate or calcium borate composite, and a calcium soap of fatty acid having 12 to 24 carbon atoms. The above components are uniformly dispersed in an oil phase medium. The content of high base number calcium sulfonate in the lubricating grease is less than 22 wt %, and the lubricating grease has a worked cone penetration of 295 or less.

A sulfonate-based grease composition and method of manufacture comprising (1) addition of both overbased calcium sulfonate and overbased magnesium sulfonate in a ratio range of 60:40 to 100:1, with the magnesium sulfonate added all at once, a portion prior to conversion and another portion after conversion, and/or one more delay periods between the addition of water or other reactive ingredient and the addition of magnesium sulfonate; (2) one or more delay periods between the addition of at least a portion of a facilitating acid and at least a portion of the next subsequently added ingredient; (3) no conventional non-aqueous converting agents added prior to conversion; or (4) a combination thereof. The grease has a high dropping point and reduced thickener yield.

A sulfonate-based grease composition and method of manufacture comprising (1) addition of both overbased calcium sulfonate and overbased magnesium sulfonate in a ratio range of 60:40 to 100:1, with the magnesium sulfonate added all at once, a portion prior to conversion and another portion after conversion, and/or one more delay periods between the addition of water or other reactive ingredient and the addition of magnesium sulfonate; (2) one or more delay periods between the addition of at least a portion of a facilitating acid and at least a portion of the next subsequently added ingredient; (3) no conventional non-aqueous converting agents added prior to conversion; or (4) a combination thereof. The grease has a high dropping point and reduced thickener yield.

To provide a grease-sealed bearing that is superior in fretting wear resistance and sealing performance when used under an oscillation condition with acceleration and deceleration such as a condition used in a robot joint. A grease-sealed bearing 1 includes an inner ring 2 and an outer ring 3 that are raceway rings, a plurality of rolling elements 4 interposed between the inner ring 2 and the outer ring 3, and a grease composition 7 sealed around the rolling elements 4. The bearing oscillates such that a bearing rotational direction changes while accelerating and decelerating. The grease composition contains a base oil and a thickener. The worked penetration of the grease composition is 310 or more. The thickener is a calcium sulfonate complex soap.

To provide a grease-sealed bearing that is superior in fretting wear resistance and sealing performance when used under an oscillation condition with acceleration and deceleration such as a condition used in a robot joint. A grease-sealed bearing 1 includes an inner ring 2 and an outer ring 3 that are raceway rings, a plurality of rolling elements 4 interposed between the inner ring 2 and the outer ring 3, and a grease composition 7 sealed around the rolling elements 4. The bearing oscillates such that a bearing rotational direction changes while accelerating and decelerating. The grease composition contains a base oil and a thickener. The worked penetration of the grease composition is 310 or more. The thickener is a calcium sulfonate complex soap.

The invention discloses a lubricating grease with thixotropy and a preparation method thereof. The lubricating grease comprises a polyurea/high base number calcium sulfonate composite thickener, colloidally dispersed calcium carbonate solid particles in the form of calcite, a calcium borate or calcium borate composite, and a calcium soap of fatty acid having 12 to 24 carbon atoms. The above components are uniformly dispersed in an oil phase medium. The content of high base number calcium sulfonate in the lubricating grease is less than 22 wt %.

The invention discloses a lubricating grease with thixotropy and a preparation method thereof. The lubricating grease comprises a polyurea/high base number calcium sulfonate composite thickener, colloidally dispersed calcium carbonate solid particles in the form of calcite, a calcium borate or calcium borate composite, and a calcium soap of fatty acid having 12 to 24 carbon atoms. The above components are uniformly dispersed in an oil phase medium. The content of high base number calcium sulfonate in the lubricating grease is less than 22 wt %.

A sulfonate-based grease composition and method of manufacture comprising (1) addition of both overbased calcium sulfonate and overbased magnesium sulfonate in a ratio range of 60:40 to 100:1, with the magnesium sulfonate added all at once, a portion prior to conversion and another portion after conversion, and/or one more delay periods between the addition of water or other reactive ingredient and the addition of magnesium sulfonate; (2) one or more delay periods between the addition of at least a portion of a facilitating acid and at least a portion of the next subsequently added ingredient; (3) no conventional non-aqueous converting agents added prior to conversion; or (4) a combination thereof. The grease has a high dropping point and reduced thickener yield.

A sulfonate-based grease composition and method of manufacture comprising (1) addition of both overbased calcium sulfonate and overbased magnesium sulfonate in a ratio range of 60:40 to 100:1, with the magnesium sulfonate added all at once, a portion prior to conversion and another portion after conversion, and/or one more delay periods between the addition of water or other reactive ingredient and the addition of magnesium sulfonate; (2) one or more delay periods between the addition of at least a portion of a facilitating acid and at least a portion of the next subsequently added ingredient; (3) no conventional non-aqueous converting agents added prior to conversion; or (4) a combination thereof. The grease has a high dropping point and reduced thickener yield.

An extremely rheopectic sulfonate-based grease composition and method comprising adding overbased calcium sulfonate, overbased magnesium sulfonate, and a facilitating acid, using a particular type of overbased calcium sulfonate and/or methods for adding overbased calcium sulfonate relative to the magnesium sulfonate and facilitating acid to favor the reaction between the magnesium sulfonate and facilitating acid. A preferred overbased calcium sulfonate comprises benzene rings having multiple alkyl groups. Preferred methods comprise (1) adding all calcium sulfonate after adding the magnesium sulfonate and facilitating acid, (2) adding a first portion of calcium sulfonate with the magnesium sulfonate before adding the facilitating acid and a second portion of calcium sulfonate after the facilitating acid, and/or (3) one or more calcium sulfonate delay periods relative to adding the facilitating acid. The extremely rheopectic grease is fluid and pourable and only takes on a grease structure after milling or shearing.