Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Inorganic compound
Reexamination Certificate
2001-09-28
2003-10-14
McAvoy, Ellen M. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Inorganic compound
C508S156000, C508S306000, C508S390000, C508S413000
Reexamination Certificate
active
06632781
ABSTRACT:
BACKGROUND OF THE INVENTION
FIELD OF THE INVENTION
This invention is directed, in part, to novel lubricant compositions. These compositions comprise an alkali metal borate; a polyalkylene succinic anhydride including mixtures and/or derivatives thereof; and a metal salt of a polyisobutenyl sulfonate. Surprisingly, these compositions have improved compatibility, extreme pressure properties and/or water tolerance over compositions comprising other metal sulfonates.
This invention is also directed, in part, to methods for improving the water tolerance of a lubricant composition comprising an alkali metal borate. Such methods employ compositions comprising an alkali metal borate; and a polyalkylene succinic anhydride including mixtures and/or derivatives thereof; and a metal salt of a polyisobutenyl sulfonate.
REFERENCES
The following references are cited in this application as superscript numbers:
1
Peeler, U.S. Pat. No. 3,313,727, Alkali Metal Borate EP. Lubricants, issued Apr. 11, 1967
2
Adams, U.S. Pat. No. 3,912,643, Lubricant Containing Neutralized Alkali Metal Borates, issued Oct. 14, 1975
3
Sims, U.S. Pat. No. 3,819,521, Lubricant Containing Dispersed Borate and a Polyol, issued Jun. 25, 1974
4
Adams, U.S. Pat. No. 3,853,772, Lubricant Containing Alkali Metal Borate Dispersed with a Mixture of Dispersants, issued Dec. 10, 1974
5
Adams, U.S. Pat. No. 3,997,454, Lubricant Containing Potassium Borate, issued Dec. 14, 1976
6
Adams, U.S. Pat. No. 4,089,790, Synergistic Combinations of Hydrated Potassium Borate, Antiwear Agents, and Organic Sulfide Antioxidants, issued May 16, 1978
7
Adams, U.S. Pat. No. 4,163,729, Synergistic Combinations of Hydrated Potassium Borate, Antiwear Agents, and Organic Sulfide Antioxidants, issued Aug. 7, 1979
8
Frost, U.S. Pat. No. 4,263,155, Lubricant Composition Containing an Alkali Metal Borate and a Sulfur-Containing Polyhydroxy Compound, U.S. Pat. No. 5,461,184, issued Oct. 24, 1995
9
Frost, U.S. Pat. No. 4,401,580, Lubricant Composition Containing an Alkali Metal Borate and an Ester-Polyol Compound, issued Aug. 30, 1983
10
Frost, U.S. Pat. No. 4,472,288, Lubricant Composition Containing an Alkali Metal Borate and an Oil-Soluble Amine Salt of a Phosphorus Compound, issued Sep. 18, 1984
11
Clark, U.S. Pat. No. 4,584,873, Automotive Friction Reducing Composition, issued Aug. 13, 1985
12
Brewster, U.S. Pat. No. 3,489,619, Heat Transfer and Quench Oil, issued Jan. 13, 1970
All of the above references are herein incorporated by reference in their entirety to the same extent as if each individual publication or patent was specifically and individually indicated to be incorporated by reference in its entirety.
STATE OF THE ART
High load conditions often occur in gear sets such as those used in automobile transmissions and differentials, pneumatic tools, gas compressors, centrifuges, high-pressure hydraulic systems, metal workings and similar devices as well as in many types of bearings. When employed in such environments, it is conventional to add an extreme-pressure agent to the lubricant composition and, in this regard, alkali metal borates are well known extreme-pressure agents for such compositions.
1-12
Because the alkali metal borate is insoluble in lubricant oil media, it is conventional to include a dispersant/detergent in such compositions in order to facilitate the formation of a homogenous dispersion. Examples of dispersant/detergents include ionic surface-active agents such as metal salts of oil soluble acidic organic compounds, e.g., sulfonates, carboxylates and phenolates, as well as non-ionic surface-active agents such as alkenyl succinimides or other nitrogen containing dispersants.
1-4
It is also conventional to employ the alkali metal borate at particle sizes of less than 1 micron in order to facilitate the formation of the homogenous dispersion.
11
The use of alkali metal borates in lubricant compositions is complicated by the presence of water in the environment where the composition is employed. Conventional preparation methods remove essentially all the water from the media
12
. However, when the presence of water exceeds a threshold concentration in the lubricant composition, the borate crystallizes out of the composition and forms hard granules. These granules cause severe noise in the lubricated systems and can severely damage the gears or bearings themselves as well as leading to seal leakage.
10
Further, borate lost by crystallization decreases the extreme pressure properties of the lubricant composition.
On the other hand, lubricant compositions employing alkali metal borates are often employed in environments where water is invariably present.
In view of the above, enhanced water tolerance of lubricant compositions comprising an alkali metal borate would be particularly beneficial.
SUMMARY OF THE INVENTION
This invention is directed to the novel and unexpected discovery that enhanced water tolerance and lubricant oil compatibility for alkali metal borates can be achieved by employing a dispersant mixture comprising:
a) a polyalkylene succinic dispersant which is selected from the group consisting of a polyalkylene succinic anhydride, a non-nitrogen containing derivative of the polyalkylene succinic anhydride, mixtures of polyalkylene succinic anhydrides, mixtures of non-nitrogen containing derivatives of the polyalkylene succinic anhydride and mixtures of one or more polyalkylene succinic anhydrides and one or more non-nitrogen containing derivatives of polyalkylene succinic anhydrides; and
b) a metal salt of a polyisobutenyl sulfonate.
Accordingly, in one of its composition aspects, this invention is directed to a lubricant composition which comprises a base oil of lubricating viscosity, a dispersed hydrated alkali metal borate, and a dispersant mixture comprising:
a) a polyalkylene succinic dispersant which is selected from the group consisting of a polyalkylene succinic anhydride, a non-nitrogen containing derivative of the polyalkylene succinic anhydride, mixtures of polyalkylene succinic anhydrides, mixtures of non-nitrogen containing derivatives of the polyalkylene succinic anhydride, and mixtures of one or more polyalkylene succinic anhydrides and one or more non-nitrogen containing derivatives of the polyalkylene succinic anhydride; and
b) a metal salt of a polyisobutenyl sulfonate.
Preferably, the dispersed hydrated alkali metal borate is present in a ratio of at least 2:1 relative to the dispersant mixture of polyalkylene succinic dispersant and polyisobutenyl sulfonate. More preferably, the ratio of dispersed hydrated alkali metal borate to dispersant mixture is from 2:1 up to 10:1. Most preferably the ratio is 5:2.
Preferably, the dispersed hydrated alkali metal borate is a dispersed hydrated sodium borate. Even more preferably the dispersed hydrated sodium borate and has a sodium to boron ratio of from about 1:2.75 to about 1:3.25.
In a particularly preferred embodiment, the dispersed hydrated alkali metal borate is a hydrated sodium metal borate having a hydroxyl:boron ratio (OH:B) of from about 0.8:1 to 1.6:1 (more preferably about 0.8:1 to 1:1) and a sodium to boron ratio of from about 1:2.75 to 1:3.25 and the polyalkylene succinic anhydride is a polyisobutenyl succinic anhydride.
Preferably, the hydrated alkali metal borate contains small amounts of a water soluble oxo anion. Only from 0.001 moles to 0.11 moles of water soluble oxo anion should be present per mole of boron. This water-soluble oxo anion can include nitrate, sulfate, carbonate, phosphate, pyrophosphate, silicate, aluminate, germanate, stannate, zincate, plumbate, titanate, molybdate, tungstate, vanadate, niobate, tantalate, uranates, or can include the isopolymolybdates and isopolytungstates, or the heteropolymolybdates and heteropolytungstates, or mixtures thereof.
Preferably, the polyalkylene succinic dispersant, is a dispersant selected from a polyalkylene succinic anhydride or a mixture of polyalkylene succinic anhydrides. More preferably, the polyalkylene succinic anhydride is a polyisobutenyl succinic anhydride. In one
Harrison James J.
Nelson Kenneth D.
Caroli Claude J.
Chevron Oronite Company LLC
Foley Joseph P.
McAvoy Ellen M.
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