Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Heavy metal or aluminum in an organic phosphorus compound...
Reexamination Certificate
1999-07-16
2001-12-25
Johnson, Jerry D. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Heavy metal or aluminum in an organic phosphorus compound...
C508S399000, C508S562000
Reexamination Certificate
active
06333298
ABSTRACT:
The present invention relates to lubricating oil compositions. More particularly, the present invention relates to lubricating oil compositions, which exhibit improvements in economy and fuel economy retention properties without the need for organo molybdenum additives and which have low volatility.
BACKGROUND OF THE INVENTION
It is well known that molybdenum provides enhanced fuel economy when used in lubricants for gasoline or diesel fueled engines, including both short and long term fuel economy (i.e., fuel economy retention properties). The prior proposals typically use molybdenum at levels greater than 350 ppm up to 2,000 ppm in additive packages, which contain one or more detergents, anti-wear agents, dispersants, friction modifiers, and the like.
The present inventors have found that fuel economy and fuel economy retention properties can be improved to meet the requirements of the next generation of motor oil certification such as the proposed ILSAC GF-3 standards (International Lubricants Standardization and Approval Committee), without the use of molybdenum which is commonly used in conventional additive packages, thus providing a less expensive lubricating oil composition.
SUMMARY OF THE INVENTION
The present invention concerns a lubricating oil composition which exhibits improved fuel economy and fuel economy retention properties, the composition comprising: (a) a major amount of a base stock oil, the base stock oil containing at least 50% by weight of a hydrocarbon mineral oil, the base stock oil having a kinematic viscosity (kV) of 4.0 to 5.5 mm
2
/s (cSt) at 100° C., 95 wt. % or more saturates, a viscosity index of at least 120, 25 wt. % or less napthenics (cycloparaffins) and a NOACK volatility of 15.5% or less; (b) a calcium detergent and (c) an organic friction modifier. The composition has a NOACK volatility of about 15 wt. % or less, and contains from about 0.058 to 0.58 wt. % calcium from the calcium detergent and is free of any molybdenum additives. The composition may be prepared by the admixture of the ingredients and such compositions are a further embodiment of this invention.
DESCRIPTION OF THE PREFERRED EMBODIMENTS
Base Stock Oil
The base stock oil should contain 50%-100% by weight of a hydrocarbon mineral oil, such as 70-95 wt. % mineral oil. Blends of hydrocarbon mineral oil and synthetic oils are suitable so long as the base stock oil used to prepare the lubricating oil composition of this invention has these properties: a kinematic viscosity of 4-5.5 mm
2
/s (cSt) at 100° C., 95% by weight or more of saturated organic compounds (ASTM D 2007), 25% by weight or less napthenic (cycloparaffinic) hydrocarbons (ASTM D3238), a viscosity index of at least 120 and a NOACK volatility of 15.5 wt. % or less.
Examples of suitable base stocks may be found in one or more of the base stock groups, or mixtures of said base stock groups, set forth in the American Petroleum Institute (API) publication “Engine Oil Licensing and Certification System”, Industry Services Department, Fourteenth Edition, December 1996, Addendum 1, December 1998.
a) Group I base stocks contain less than 90 percent saturates and/or greater than 0.03 percent sulfur and have a viscosity index greater than or equal to 80 and less than 120 using the test methods specified in Table A below.
b) Group II base stocks contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 80 and less than 120 using the test methods specified in Table A below.
c) Group III base stocks contain greater than or equal to 90 percent saturates and less than or equal to 0.03 percent sulfur and have a viscosity index greater than or equal to 120 using the test methods specified in Table A below.
d) Group IV base stocks are polyalphaolefins (PAO), a synthetic base stock.
e) Group V base stocks include all other base stocks not included in Groups I, II, III, or IV.
TABLE A
Analytical Methods for Testing Base Stocks
Property
Test Method
Saturates
ASTM D2007
Viscosity Index
ASTM D2270
Sulfur
ASTM D2622, D4292,
D4927, or D3120
Napthenics (cycloparaffins)
ASTM D3238
Preferred base stock oils are (a) Group III base stocks or blends of Group III base stock oils with Group I, Group II or Group IV base stocks.
Examples of other base stock oils of lubricating viscosity which may be blended with hydrocarbon mineral oils to form the base stock oil useful in this invention include mineral oils and vegetable oils, oils derived from coal and shale, polymerized and interpolymerized olefins such as chlorinated polybutylenes, alkylbenzenes, alkylated polyphenyls, alkylated diphenyl ethers, alkylene oxide polymers, fatty acid esters, polyol esters, oxo acid esters of glycols, esters of dicarboxylic acid with monohydric and polyhydric alcohols such as dibutyl adipate, didecyl phthalate and the like.
Calcium Detergent
The present invention requires the presence of at least one calcium detergent. Detergents aid in reducing deposits that build up in an engine and act as an acid neutralizer or rust inhibitor. This in turn reduces engine wear and corrosion.
The use of a calcium detergent in combination with the base stock oils in the composition of this invention offers fuel economy advantages as demonstrated by coefficient of friction data.
The calcium detergent used in this invention may be neutral or overbased and may comprise calcium phenates, salicylates, sulfonates, or mixtures thereof, with calcium sulfonates being particularly preferred. Preferably, the detergent will be overbased, that is the Total Base Number (TBN) will be at least 100 but usually between 100 and 500, more preferably between 150 and 450, and most preferably between 200 and 400. The most preferred detergent for use in this invention is an overbased calcium sulfonate having a TBN between 200 and 400.
The process of overbasing a metal detergent means that a stoichiometric excess of the metal is present over what is required to neutralized the anion of the salt. It is the excess metal from overbasing that has the effect of neutralizing acids which may build up.
In the present invention, overbased calcium sulfonate detergents may be derived from the salt of an oil soluble sulfonic acid, where a mixture of an oil soluble sulfonate or alkaryl sulfonic acid is combined with calcium and heated to neutralize the sulfonic acid that is present. This forms a dispersed carbonate complex by reacting the excess calcium with carbon dioxide. The sulfonic acids typically are obtained by the sulfonation of alkyl substituted aromatic hydrocarbons such as those obtained from the fractionation of petroleum or by the alkylation of aromatic hydrocarbons. Examples include those obtained by alkylating benzene, toluene, xylene, naphthalene, diphenyl or their halogen derivatives such as chlorobenzene, chlorotoluene, and chloronaphthalene. The alkylation may be carried out in the presence of a catalyst with alkylating agents having from 3 to more than 30 carbon atoms. For example, haloparaffins, olefins obtained by dehydrogenation of paraffins, or polyolefins produced from ethylene or propylene are all suitable. The alkaryl sulfonates usually contain from about 9 to about 70 or more carbon atoms, preferably from about 16 to about 50 carbon atoms per alkyl substituted aromatic moiety.
The oil soluble sulfonates are neutralized with a calcium compound. The amount of calcium that is used to neutralize the oil soluble sulfonate is carefully chosen with regard to the desired total base number (TBN) of the final product.
In the present invention, the amount of calcium detergents used can vary broadly, but typically will be from about 0.5 to about 5 wt. %, based on the total weight of the composition. This corresponds to about 0.058 to 0.58 wt. % calcium from the calcium detergent in the finished composition. Preferably the composition will contain between about 0.112 to 0.42 wt. % of calcium from the calcium detergent.
Calcium phenates and calcium salicylates may be prepared using a variety of metho
Hartley Rolfe J.
Miyoshi Taisuke
Waddoups Malcolm
Infineum International Limited
Johnson Jerry D.
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