Solid anti-friction devices – materials therefor – lubricant or se – Lubricants or separants for moving solid surfaces and... – Organic oxygen compound
Reexamination Certificate
2001-10-16
2003-08-26
Howard, Jacqueline V. (Department: 1764)
Solid anti-friction devices, materials therefor, lubricant or se
Lubricants or separants for moving solid surfaces and...
Organic oxygen compound
C508S579000, C508S584000, C508S585000, C508S586000, C508S587000
Reexamination Certificate
active
06610637
ABSTRACT:
BACKGROUND OF THE INVENTION
The present invention relates to synthetic based lubricants which are particularly useful for lubricating heavy duty diesel engines.
Specifications for modern engine lubricants, such as those for heavy duty diesel engines, especially in Europe, indicate a longer interval between oil changes than has been customary in the past. In order to formulate engine oils with longer drain intervals, higher levels of certain additives have been incorporated, typically greater than 1.7% by weight detergent substrate and greater than 10 TBN (Total Base Number, ASTM D2896) in the finished lubricant. Additionally, synthetic base stocks have been used to improve the thermo-oxidative stability of the base oils. These high levels of detergent soap substrate and TBN provide improved piston cleanliness and reduced engine wear over drain intervals which may be in excess of 100,000 km. However, the high level of detergent can cause higher levels of valve train wear, as measured in the Cummins M11 valve train wear test.
To address the problem of increased valve train wear, a heavy duty diesel lubricant has now been formulated using a selection of synthetic base oils, a dispersant-viscosity modifier, and a sulfur-free functionalized alkyl phenol detergent. The preferred lubricant also exhibits good emissions performance.
U.S. Pat. No. 5,719,107, Outten et al., Feb. 17, 1998, discloses a crankcase lubricant for diesel engines, comprising an admixture of a major amount of an oil of lubricating viscosity, at least 4 mass % dispersant, at least 0.3 mass % of a metal phenate, which may be neutral or overbased, and various other components. The oil can be any of the synthetic or natural oils, or mixtures. The oil has a viscosity of about 2.5 to about 12 mm
2
/sec. Multifunctional viscosity modifiers that also function as dispersants are also disclosed. Suitable metal phenates include calcium, magnesium, and mixtures of the two.
U.S. Pat. No. 2,647,873, Matthews et al., Aug. 4, 1953, discloses compounds which are suitable as additional agents to lubricating oils and greases. Metal salts and condensates are prepared from the following ingredients: an aromatic compound containing a polar radical or radicals (e.g., phenols), and aldehydes such as formaldehyde. The Ca, Mg, Sr, Cu, Zn, Al, and Sn salts of certain of these condensation products are disclosed.
SUMMARY OF THE INVENTION
The present invention provides a lubricant suitable for use in a diesel engine, comprising:
(a) a synthetic base oil composition, said base oil overall having a kinematic viscosity of at least 4.8×10
−6
m
2
/s (4.8 cSt) at 100° C. and a viscosity index of at least 110;
(b) a dispersant-viscosity modifier; and
(c) a sulfur-free functionalized hydrocarbyl (or alternatively, alkyl) phenol detergent.
The invention also provides a method for lubricating a crankcase-lubricated diesel engine comprising supplying such a lubricant to the crankcase thereof.
DETAILED DESCRIPTION OF THE INVENTION
Various preferred features and embodiments will be described below by way of non-limiting illustration.
The first component of the present lubricants is a selected synthetic base oil or mixture of base oils. Synthetic oils in general include hydrocarbon oils such as polymerized and interpolymerized olefins, e.g., polyalphaolefins (PAOs). Typically, polyalphaolefins are derived from monomers having from about 4 to about 30, or from about 4 to about 20, or from about 6 to about 16 carbon atoms. Typically, PAOs are hydrogenated. Examples of useful PAOs polybutylenes, polypropylenes, propylene-isobutylene copolymers, poly(1-hexenes, poly(1-octenes), poly(1-decenes),and mixtures thereof).
Alkylbenzenes are another species of synthetic hydrocarbon oil. Alkylbenzenes include generally C
10-13
alkyl-substituted benzenes, including dodecylbenzenes and bisdodecylbenzenes such as m-bisdodecylbenzene; tetradecylbenzenes; dinonylbenzenes; and di(2-ethylhexyl)-benzenes;
Other species of synthetic hydrocarbon oils include polyphenyls (e.g., biphenyls, terphenyls, and alkylated polyphenyls), alkylated diphenyl ethers and alkylated diphenyl sulfides and the derivatives, analogs, and homologues thereof.
Group III base oils are also sometimes considered to be synthetic base oils, and for the purposes of this invention they can be considered to be included within the definition of “synthetic base oils.” Group III base oils are defined by the API Base Oil Interchange Guidelines as having the following minimum characteristics: ≦0.03% sulfur, ≧90% saturates, and ≧120 viscosity index. These are generally oils which are derived from natural stocks (as opposed to being derived from synthetic sources), but are so highly refined that they can exhibit the performance and viscosity parameters of other synthetic base oils.
Another class of synthetic base oils includes alkylene oxide polymers and interpolymers and derivatives thereof where the terminal hydroxyl groups have been modified by esterification, etherification, or similar reaction constitute. These are exemplified by the oils prepared through polymerization of ethylene oxide or propylene oxide, the alkyl and aryl ethers of these polyoxyalkylene polymers (e.g., methylpolyisopropylene glycol ether having an average molecular weight of 1,000 diphenyl ether of polyethylene glycol having a molecular weight of 500-1,000, diethyl ether of polypropylene glycol having a molecular weight of 1,000-1,500) or mono- and polycarboxylic esters thereof, for example, the acetic acid esters, mixed C
3
-C
8
fatty acid esters, or the C
13
Oxo acid diester of tetraethylene glycol.
Another suitable class of synthetic lubricating oils comprises synthetic esters, including the esters of dicarboxylic acids (e.g., phthalic acid, succinic acid, alkyl succinic acids and alkenyl succinic acids, maleic acid, azelaic acid, suberic acid, sebacic acid, fumaric acid, adipic acid, dodecanedioic acid, linoleic acid dimer, malonic acid, alkyl malonic acids, and alkenyl malonic acids) with a variety of alcohols (e.g., butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol, ethylene glycol, diethylene glycol monoether, and propylene glycol). Specific examples of these esters include dibutyl adipate, di(2-ethylhexyl sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid dimer, and the complex ester formed by reacting one mole of sebacic acid with two moles of tetraethylene glycol and two moles of 2-ethylhexanoic acid.
Esters useful as synthetic oils also include those made from C
5
to C
12
monocarboxylic acids and polyols and polyol ethers such as neopentyl glycol, trimethylolpropane, pentaerythritol, dipentaerythritol, and tripentaerythritol. Examples of synthetic monoester oils which are commercially available include Emery™ 2935, Emery™ 2971, Priolube™ 1976, Priolube™ 3999, Nycobase™ 8311, Nycobase™ 8885, and Nycobase™ 8886.
A useful synthetic base oil composition is selected from one or more polyalphaolefin oils, one or more synthetic esters, and one or more alkylbenzenes, or mixtures thereof. In one embodiment the base oil is a mixture of a polyalphaolefin oil having a viscosity of 4 to 8×10
−6
m
2
/s (4-8 cSt) at 100° C., alternatively in an amount of 60 to 95% by weight, a C
10-13
alkyl-substituted benzene, or in an amount of 5 to 20 percent by weight, and optionally a synthetic monoester, for instance, in an amount of 0 to 20 percent by weight.
The synthetic base oil composition used in the present lubricant should exhibit a kinematic viscosity (ASTM 445) of at least 4.8×10
−6
m
2
/s (4.8 cSt) at 100° C. and alternatively at least 5.0, 5.1 or 5.3, and optionally up to 7.0×10
−6
m
2
/s at 100° C. The base oil composition overall should also exhibit a viscosity index (ASTM 2270) of at least 110, such as at least 120, or in the range of 120 to 160. Viscosity Index or “V.I.” is an arbitrary number which indicates the resistanc
Abraham William D.
Curtis Thomas T.
Lamb Gordon D.
Esposito Michael F.
Howard Jacqueline V.
Shold David M.
The Lubrizol Corporation
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