U.S. patent application number 13/675463 was filed with the patent office on 2013-05-30 for method for improving engine fuel efficiency.
This patent application is currently assigned to EXXONMOBIL RESEARCH AND ENGINEERING COMPANY. The applicant listed for this patent is ExxonMobil Research and Engineering Company. Invention is credited to Douglas Edward Deckman, Kevin John Kelly, Kristen Amanda Lyon, William L. Maxwell.
Application Number | 20130137617 13/675463 |
Document ID | / |
Family ID | 47228078 |
Filed Date | 2013-05-30 |
United States Patent
Application |
20130137617 |
Kind Code |
A1 |
Lyon; Kristen Amanda ; et
al. |
May 30, 2013 |
METHOD FOR IMPROVING ENGINE FUEL EFFICIENCY
Abstract
A method for improving fuel efficiency, while maintaining or
improving wear protection, in an engine lubricated with a
lubricating oil by using as the lubricating oil a formulated oil
having a HTHS viscosity of less than 2.6 cP at 150.degree. C. In
one form, the formulated oil has a composition that includes a
lubricating oil base stock as a major component, and zinc dialkyl
dithio phosphate, a mixture of (i) at least two alkali metal
detergents, (ii) at least two alkaline earth metal detergents, or
(iii) one or more alkali metal detergents and one or more alkaline
earth metal detergents; and a viscosity index improver, as minor
components. The lubricating oil has a HTHS viscosity of less than
2.6 cP at 150.degree. C. The composition contains less than 2
weight percent of the viscosity index improver, based on the total
weight of the formulated oil or lubricating engine oil.
Inventors: |
Lyon; Kristen Amanda; (West
Deptford, NJ) ; Kelly; Kevin John; (Mullica Hill,
NJ) ; Maxwell; William L.; (Pilesgrove, NJ) ;
Deckman; Douglas Edward; (Mullica Hill, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ExxonMobil Research and Engineering Company; |
Annandale |
NJ |
US |
|
|
Assignee: |
EXXONMOBIL RESEARCH AND ENGINEERING
COMPANY
Annandale
NJ
|
Family ID: |
47228078 |
Appl. No.: |
13/675463 |
Filed: |
November 13, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61559294 |
Nov 14, 2011 |
|
|
|
Current U.S.
Class: |
508/374 ;
508/371; 508/372; 508/378 |
Current CPC
Class: |
C10N 2030/04 20130101;
C10N 2010/04 20130101; C10M 2219/046 20130101; C10M 167/00
20130101; C10N 2030/06 20130101; C10N 2030/68 20200501; C10N
2020/02 20130101; C10N 2030/02 20130101; C10N 2030/54 20200501;
C10M 2223/045 20130101; C10M 2207/262 20130101; C10N 2010/02
20130101; C10M 169/02 20130101; C10N 2040/25 20130101 |
Class at
Publication: |
508/374 ;
508/371; 508/378; 508/372 |
International
Class: |
C10M 169/02 20060101
C10M169/02 |
Claims
1. A method for improving fuel efficiency, while maintaining or
improving wear protection, in an engine lubricated with a
lubricating oil by using as the lubricating oil a formulated oil
having a HTHS viscosity of less than 2.6 cP at 150.degree. C., said
formulated oil having a composition comprising a lubricating oil
base stock as a major component, and a zinc dialkyl dithio
phosphate, a mixture of (i) at least two alkali metal detergents,
(ii) at least two alkaline earth metal detergents, or (iii) one or
more alkali metal detergents and one or more alkaline earth metal
detergents; and a viscosity index improver, as minor components;
wherein said composition contains less than 2 weight percent of the
viscosity index improver, based on the total weight of the
formulated oil; and wherein said composition is sufficient for the
formulated oil to pass wear protection requirements of one or more
engine tests selected from TU3M, Sequence IIIG, Sequence IVA and
OM646LA.
2. The method of claim 1 wherein the base oil comprises a Group I,
Group II, Group III, Group IV or Group V base oil.
3. The method of claim 1 wherein the lubricating oil base stock
comprises a poly alpha olefin (PAO) or gas-to-liquid (GTL) oil base
stock.
4. The method of claim 1 wherein the alkali metal detergents and
alkaline earth metal detergents are selected from metallic
salicylates and sulfonates, and wherein the metallic salicylates
and sulfonates are selected from calcium and magnesium.
5. The method of claim 1 wherein the ZDDP is a secondary dialkyl
dithio phosphate.
6. The method of claim 1 wherein said composition contains less
than 1 weight percent of the viscosity index improver, based on the
total weight of the formulated oil.
7. The method of claim 1 wherein the oil base stock is present in
an amount of from 70 weight percent to 95 weight percent, the zinc
dialkyl dithio phosphate (ZDDP) is present in an amount of from 0.4
weight percent to 1.2 weight percent, and the mixture of (i) at
least two alkali metal detergents, (ii) at least two alkaline earth
metal detergents, or (iii) one or more alkali metal detergents and
one or more alkaline earth metal detergents, is present in an
amount of from 1.0 weight percent to 6.0 weight percent, based on
the total weight of the formulated oil.
8. The method of claim 1 wherein said composition contains less
than 0.5 weight percent of the viscosity index improver, based on
the total weight of the formulated oil.
9. The method of claim 1 wherein the formulated oil has a HTHS
viscosity of less than 2.4 cP at 150.degree. C.
10. The method of claim 1 wherein the lubricating oil is a
passenger vehicle engin oil (PVEO).
11. A lubricating engine oil having a composition comprising a
lubricating oil base stock as a major component, and a zinc dialkyl
dithio phosphate, a mixture of (i) at least two alkali metal
detergents, (ii) at least two alkaline earth metal detergents, or
(iii) one or more alkali metal detergents and one or more alkaline
earth metal detergents; and a viscosity index improver, as minor
components; wherein said lubricating engine oil has a HTHS
viscosity of less than 2.6 cP at 150.degree. C.; wherein said
composition contains less than 2 weight percent of the viscosity
index improver, based on the total weight of the lubricating engine
oil; and wherein said composition is sufficient for the lubricating
engine oil to pass wear protection requirements of one or more
engine tests selected from TU3M, Sequence IIIG, Sequence IVA and
OM646LA.
12. The lubricating engine oil of claim 11 wherein the oil base
stock comprises a Group I, Group II Group III, Group IV or Group V
base oil.
13. The lubricating engine oil of claim 11 wherein the lubricating
oil base stock comprises a poly alpha olefin (PAO) or gas-to-liquid
(GTL) oil base stock.
14. The lubricating engine oil of claim 11 wherein the alkali metal
detergents and alkaline earth metal detergents are selected from
metallic salicylates and sulfonates, and wherein the metallic
salicylates and sulfonates are selected from calcium and
magnesium.
15. The lubricating engine oil of claim 11 wherein the ZDDP is a
secondary dialkyl dithio phosphate.
16. The lubricating engine oil of claim 11 wherein said composition
contains less than 1 weight percent of the viscosity index
improver, based on the total weight of the lubricating engine
oil.
17. The lubricating engine oil of claim 11 wherein the oil base
stock is present in an amount of from 70 weight percent to 95
weight percent, the zinc dialkyl dithio phosphate (ZDDP) is present
in an amount of from 0.4 weight percent to 1.2 weight percent, and
the mixture of (i) at least two alkali metal detergents, (ii) at
least two alkaline earth metal detergents, or (iii) one or more
alkali metal detergents and one or more alkaline earth metal
detergents, is present in an amount of from 1.0 weight percent to
6.0 weight percent, based on the total weight of the lubricating
engine oil.
18. The lubricating engine oil of claim 11 wherein said composition
contains less than 0.5 weight percent of the viscosity index
improver, based on the total weight of the lubricating engine
oil.
19. The lubricating engine oil of claim 11 which has a HTHS
viscosity of less than 2.4 cP at 150.degree. C.
20. The lubricating engine oil of claim 11 comprising a passenger
vehicle engine oil (PVEO).
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 61/559,294, filed on Nov. 14, 2011; which is
incorporated herein in its entirety by reference.
FIELD
[0002] This disclosure relates to lubricating engines using
formulated lubricating oils to improve engine fuel efficiency
without sacrificing engine durability.
BACKGROUND
[0003] Fuel efficiency requirements for passenger vehicles are
becoming increasingly more stringent. New legislation in the United
States and European Union within the past few years has set fuel
economy and emissions targets not readily achievable with today's
vehicle and lubricant technology. In order to improve lubricant
fuel economy performance, reduction of viscosity is typically the
best path; however, present day lubricant oils with a HTHS (ASTM
D4683) viscosity of less than 2.6 cP at 150.degree. C. would not be
expected to be able to provide acceptable passenger vehicle engine
durability performance.
[0004] HTHS is the measure of a lubricant's viscosity under
conditions that simulate severe engine operation. Under high
temperatures and high stress conditions, viscosity index improver
degradation can occur. As this happens, the viscosity of the oil
decreases which may lead to increased engine wear.
[0005] A viscosity index improver is typically added to engine oil
in order to provide appropriate viscosity at high and low
temperatures and thereby widen the application temperature range.
High molecular weight polymers are widely used as viscosity index
improvers. The high molecular weight polymer-based viscosity index
improver has the typical property of such improvers; that is, a
temporary viscosity decrease due to orientation, etc., occurs
during operation at high speed/high load or under other high shear
conditions, and irreversible viscosity decrease occurs due to
molecular weight decrease as a result of chopping of the polymer
molecules when the shear conditions become severe. Also, when the
viscosity of the engine oil is reduced, the engine oil film itself
becomes thinner, and the opportunity for increased engine wear
arises. Therefore, for engine oils in which a viscosity index
improver is added, if the viscosity is reduced by simply reducing
the viscosity of the base oil, it is not possible to guarantee the
oil film under high shear conditions, and engine wear can easily
occur.
[0006] Despite the advances in lubricant oil formulation
technology, there exists a need for an engine oil lubricant that
effectively improves fuel economy while providing superior antiwear
performance, and has the capability to do so through reduction or
removal of viscosity index improvers.
SUMMARY
[0007] This disclosure relates in part to a method for improving
fuel efficiency, while maintaining or improving wear protection, in
an engine lubricated with a lubricating oil by reducing the amount
of a viscosity index improver in the lubricating oil sufficient for
the lubricating oil to have a HTHS viscosity of less than 2.6 cP at
150.degree. C.
[0008] This disclosure also relates in part to a method for
improving fuel efficiency, while maintaining or improving wear
protection, in an engine lubricated with a lubricating oil by using
as the lubricating oil a formulated oil having a HTHS viscosity of
less than 2.6 cP at 150.degree. C. The formulated oil has a
composition that comprises a lubricating oil base stock as a major
component, and zinc dialkyl dithio phosphate, a mixture of (i) at
least two alkali metal detergents, (ii) at least two alkaline earth
metal detergents, or (iii) one or more alkali metal detergents and
one or more alkaline earth metal detergents; and a viscosity index
improver, as minor components. The composition contains less than 2
weight percent of the viscosity index improver, based on the total
weight of the formulated oil. The composition is sufficient for the
formulated oil to pass wear protection requirements of one or more
engine tests selected from TU3M, Sequence IIIG, Sequence IVA and
OM646LA.
[0009] This disclosure further relates in part to a lubricating
engine oil having a composition comprising a lubricating oil base
stock as a major component, and a zinc dialkyl dithio phosphate, a
mixture of (i) at least two alkali metal detergents, (ii) at least
two alkaline earth metal detergents, or (iii) one or more alkali
metal detergents and one or more alkaline earth metal detergents,
e.g., magnesium sulfonate and calcium salicylate; and a viscosity
index improver, as minor components. The lubricating engine oil has
a HTHS viscosity of less than 2.6 cP at 150.degree. C. The
composition contains less than 2 weight percent of the viscosity
index improver, based on the total weight of the lubricating engine
oil. The composition is sufficient for the lubricating engine oil
to pass wear protection requirements of one or more engine tests
selected from TU3M, Sequence IIIG, Sequence IVA and OM646LA.
[0010] This disclosure yet further relates in part to a method for
improving fuel efficiency, while maintaining or improving wear
protection, in an engine lubricated with a lubricating oil by using
as the lubricating oil a formulated oil having a HTHS viscosity of
less than 2.6 cP at 150.degree. C. The formulated oil has a
composition that comprises a lubricating oil base stock as a major
component, and zinc dialkyl dithio phosphate, and a mixture of (i)
at least two alkali metal detergents, (ii) at least two alkaline
earth metal detergents, or (iii) one or more alkali metal
detergents and one or more alkaline earth metal detergents, as
minor components. The composition can optionally contain a
viscosity index improver in an amount less than 2 weight percent,
based on the total weight of the formulated oil. The composition is
sufficient for the formulated oil to pass wear protection
requirements of one or more engine tests selected from TU3M,
Sequence IIIG, Sequence IVA and OM646LA.
[0011] This disclosure also relates in part to a lubricating engine
oil having a composition comprising a lubricating oil base stock as
a major component, and a zinc dialkyl dithio phosphate, and a
mixture of (i) at least two alkali metal detergents, (ii) at least
two alkaline earth metal detergents, or (iii) one or more alkali
metal detergents and one or more alkaline earth metal detergents,
e.g., magnesium sulfonate and calcium salicylate, as minor
components. The lubricating engine oil has a HTHS viscosity of less
than 2.6 cP at 150.degree. C. The composition can optionally
contain a viscosity index improver in an amount less than 2 weight
percent, based on the total weight of the formulated oil. The
composition is sufficient for the formulated oil to pass wear
protection requirements of one or more engine tests selected from
TU3M, Sequence IIIG, Sequence IVA and OM646LA.
[0012] In accordance with this disclosure, improvements in fuel
economy are obtained without sacrificing engine durability by a
reduction of HTHS viscosity to a level less than 2.6 cP through
reduction or removal of viscosity modifiers. Engine wear protection
is maintained even when a viscosity modifier is reduced or removed
from the engine oil formulation, leading to substantially lower
HTHS viscosities, e.g., 2.6 cP or lower at 150.degree. C.
[0013] Other objects and advantages of the present disclosure will
become apparent from the detailed description that follows.
DETAILED DESCRIPTION
[0014] All numerical values within the detailed description and the
claims herein are modified by "about" or "approximately" the
indicated value, and take into account experimental error and
variations that would be expected by a person having ordinary skill
in the art.
[0015] It has now been found that improved fuel efficiency can be
attained, while wear protection is maintained or improved, in an
engine lubricated with a lubricating oil by using as the
lubricating oil a formulated oil having a HTHS viscosity of less
than 2.6 cP at 150.degree. C. The formulated oil comprises a
lubricating oil base stock as a major component, a zinc dialkyl
dithio phosphate, and a mixture of (i) at least two alkali metal
detergents, (ii) at least two alkaline earth metal detergents, or
(iii) one or more alkali metal detergents and one or more alkaline
earth metal detergents; and a viscosity index improver, as minor
components. The lubricating oils of this disclosure are
particularly advantageous as passenger vehicle engine oil (PVEO)
products.
[0016] The lubricating oils of this disclosure provide excellent
engine protection including anti-wear performance. This benefit has
been demonstrated for the lubricating oils of this disclosure in
the Sequence IIIG/IIIGA (ASTM D7320), Sequence IVA (ASTM D6891),
PSA TU3MS (CEC L-038-94), MB OM646LA (CEC L-099-08), and
Caterpillar 1M-PC (ASTM D6618) engine tests at HTHS viscosities
less than 2.6 cP (at 150.degree. C.). The lubricating oils of this
disclosure provide improved fuel efficiency. A lower HTHS viscosity
engine oil generally provides superior fuel economy to a higher
HTHS viscosity product. This benefit has been demonstrated for the
lubricating oils of this disclosure in the MB M111 Fuel Economy
(CEC L-054-96) and Sequence VID Fuel to Economy (ASTM D7589) engine
tests. By providing outstanding engine protection at very low HTHS
viscosities, this disclosure provides improved fuel economy without
sacrificing engine durability.
[0017] The engine lubricating oil of the present disclosure has a
HTHS viscosity of less than 2.6 cP at 150.degree. C., preferably
less than 2.4 cP at 150.degree. C., and more preferably less than
2.2 cP at 150.degree. C.
[0018] The lubricating engine oils of this disclosure have a
composition sufficient to pass wear protection requirements of one
or more engine tests selected from TU3M, Sequence IIIG, Sequence
IVA, OM646LA and others.
Lubricating Oil Base Stocks
[0019] A wide range of lubricating base oils is known in the art.
Lubricating base oils that are useful in the present disclosure are
both natural oils, and synthetic oils, and unconventional oils (or
mixtures thereof) can be used unrefined, refined, or rerefined (the
latter is also known as reclaimed or reprocessed oil). Unrefined
oils are those obtained directly from a natural or synthetic source
and used without added purification. These include shale oil
obtained directly from retorting operations, petroleum oil obtained
directly from primary distillation, and ester oil obtained directly
from an esterification process. Refined oils are similar to the
oils discussed for unrefined oils except refined oils are subjected
to one or more purification steps to improve at least one
lubricating oil property. One skilled in the art is familiar with
many purification processes. These processes include solvent
extraction, secondary distillation, acid extraction, base
extraction, filtration, and percolation. Rerefined oils are
obtained by processes analogous to refined oils but using an oil
that has been previously used as a feed stock.
[0020] Groups I, II, III, IV and V are broad base oil stock
categories developed and defined by the American Petroleum
institute (API Publication 1509; www.API.org) to create guidelines
for lubricant base oils. Group I base stocks have a viscosity index
of between 80 to 120 and contain greater than 0.03% sulfur and/or
less than 90% saturates. Group II base stocks have a viscosity
index of between 80 to 120, and contain less than or equal to 0.03%
sulfur and greater than or equal to 90% saturates. Group III stocks
have a viscosity index greater than 120 and contain less than or
equal to 0.03% sulfur and greater than 90% saturates. Group IV
includes polyalphaolefins (PAO). Group V base stock includes base
stocks not included in Groups I-IV. The table below summarizes
properties of each of these five groups.
TABLE-US-00001 Base Oil Properties Saturates Sulfur Viscosity Index
Group I <90 and/or >0.03% and .gtoreq.80 and <120 Group II
.gtoreq.90 and .ltoreq.0.03% and .gtoreq.80 and <120 Group III
.gtoreq.90 and .ltoreq.0.03% and .gtoreq.120 Group IV Includes
polyalphaolefins (PAO) and GTL products Group V All other base oil
stocks not included in Groups I, II, III or IV
[0021] Natural oils include animal oils, vegetable oils (castor oil
and lard oil, for example), and mineral oils. Animal and vegetable
oils possessing favorable thermal oxidative stability can be used.
Of the natural oils, mineral oils are preferred. Mineral oils vary
widely as to their crude source, for example, as to whether they
are paraffinic, naphthenic, or mixed paraffinic-naphthenic. Oils
derived from coal or shale are also useful. Natural oils vary also
as to the method used for their production and purification, for
example, their distillation range and whether they are straight run
or cracked, hydrorefined, or solvent extracted.
[0022] Group II and/or Group III hydroprocessed or hydrocracked
basestocks, including synthetic oils such as polyalphaolefins,
alkyl aromatics and synthetic esters are also well known basestock
oils.
[0023] Synthetic oils include hydrocarbon oil. Hydrocarbon oils
include oils such as polymerized and interpolymerized olefins
(polybutylenes, polypropylenes, propylene isobutylene copolymers,
ethylene-olefin copolymers, and ethylene-alphaolefin copolymers,
for example). Polyalphaolefin (PAO) oil base stocks are commonly
used synthetic hydrocarbon oil. By way of example, PAOs derived
from C.sub.8, C.sub.10, C.sub.12, C.sub.14 olefins or mixtures
thereof may be utilized. See U.S. Pat. Nos. 4,956,122; 4,827,064;
and 4,827,073.
[0024] The number average molecular weights of the PAOs, which are
known materials and generally available on a major commercial scale
from suppliers such as ExxonMobil Chemical Company, Chevron
Phillips Chemical Company, BP, and others, typically vary from 250
to 3,000, although PAO's may be made in viscosities up to 100 cSt
(100.degree. C.). The PAOs are typically comprised of relatively
low molecular weight hydrogenated polymers or oligomers of
alphaolefins which include, but are not limited to, C.sub.2 to
C.sub.32 alphaolefins with the C.sub.8 to C.sub.16 alphaolefins,
such as 1-octene, 1-decene, 1-dodecene and the like, being
preferred. The preferred polyalphaolefins are poly-1-octene,
poly-1-decene and poly-1-dodecene and mixtures thereof and mixed
olefin-derived polyolefins. However, the dimers of higher olefins
in the range of C.sub.14 to C.sub.18 may be used to provide low
viscosity basestocks of acceptably low volatility. Depending on the
viscosity grade and the starting oligomer, the PAOs may be
predominantly trimers and tetramers of the starting olefins, with
minor amounts of the higher oligomers, having a viscosity range of
1.5 to 12 cSt.
[0025] The PAO fluids may be conveniently made by the
polymerization of an alphaolefin in the presence of a
polymerization catalyst such as the Friedel-Crafts catalysts
including, for example, aluminum trichloride, boron trifluoride or
complexes of boron trifluoride with water, alcohols such as
ethanol, propanol or butanol, carboxylic acids or esters such as
ethyl acetate or ethyl propionate. For example the methods
disclosed by U.S. Pat. No. 4,149,178 or 3,382,291 may be
conveniently used herein. Other descriptions of PAO synthesis are
found in the following U.S. Pat. Nos. 3,742,082; 3,769,363;
3,876,720; 4,239,930; 4,367,352; 4,413,156; 4,434,408; 4,910,355;
4,956,122; and 5,068,487. The dimers of the C.sub.14 to C.sub.18
olefins are described in U.S. Pat. No. 4,218,330.
[0026] The hydrocarbyl aromatics can be used as base oil or base
oil component and can be any hydrocarbyl molecule that contains at
least 5% of its weight derived from an aromatic moiety such as a
benzenoid moiety or naphthenoid moiety, or their derivatives. These
hydrocarbyl aromatics include alkyl benzenes, alkyl naphthalenes,
alkyl diphenyl oxides, alkyl naphthols, alkyl diphenyl sulfides,
alkylated bis-phenol A, alkylated thiodiphenol, and the like. The
aromatic can be mono-alkylated, dialkylated, polyalkylated, and the
like. The aromatic can be mono- or poly-functionalized. The
hydrocarbyl groups can also be comprised of mixtures of alkyl
groups, alkenyl groups, alkynyl, cycloalkyl groups, cycloalkenyl
groups and other related hydrocarbyl groups. The hydrocarbyl groups
can range from C.sub.6 up to C.sub.60 with a range of C.sub.8 to
C.sub.20 often being preferred. A mixture of hydrocarbyl groups is
often preferred, and up to three such substituents may be present.
The hydrocarbyl group can optionally contain sulfur, oxygen, and/or
nitrogen containing substituents. The aromatic group can also be
derived from natural (petroleum) sources, provided at least 5% of
the molecule is comprised of an above-type aromatic moiety.
Viscosities at 100.degree. C. of approximately 3 cSt to 50 cSt are
preferred, with viscosities of approximately 3.4 cSt to 20 cSt
often being more preferred for the hydrocarbyl aromatic component.
In one embodiment, an alkyl naphthalene where the alkyl group is
primarily comprised of 1-hexadecene is used. Other alkylates of
aromatics can be advantageously used. Naphthalene or methyl
naphthalene, for example, can be alkylated with olefins such as
octene, decene, dodecene, tetradecene or higher, mixtures of
similar olefins, and the like. Useful concentrations of hydrocarbyl
aromatic in a lubricant oil composition can be 2% to 25%,
preferably 4% to 20%, and more preferably 4% to 15%, depending on
the application.
[0027] Esters comprise a useful base stock. Additive solvency and
seal compatibility characteristics may be secured by the use of
esters such as the esters of dibasic acids with monoalkanols and
the polyol esters of monocarboxylic acids. Esters of the former
type include, for example, the esters of dicarboxylic acids such as
phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic
acid, maleic acid, azelaic acid, suberic acid, sebacic acid,
fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl
malonic acid, alkenyl malonic acid, etc., with a variety of
alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol,
2-ethylhexyl alcohol, etc. Specific examples of these types of
esters include dibutyl adipate, di(2-ethylhexyl) sebacate,
di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate,
diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl
sebacate, etc.
[0028] Particularly useful synthetic esters are those which are
obtained by reacting one or more polyhydric alcohols, preferably
the hindered polyols (such as the neopentyl polyols, e.g.,
neopentyl glycol, trimethylol ethane,
2-methyl-2-propyl-1,3-propanediol, trimethylol propane,
pentaerythritol and dipentaerythritol) with alkanoic acids
containing at least 4 carbon atoms, preferably C.sub.5 to C.sub.30
acids such as saturated straight chain fatty acids including
caprylic acid, capric acid, lauric acid, myristic acid, palmitic
acid, stearic acid, arachic acid, and behenic acid, or the
corresponding branched chain fatty acids or unsaturated fatty acids
such as oleic acid, or mixtures of any of these materials.
[0029] Suitable synthetic ester components include the esters of
trimethylol propane, trimethylol butane, trimethylol ethane,
pentaerythritol and/or dipentaerythritol with one or more
monocarboxylic acids containing from 5 to 10 carbon atoms. These
esters are widely available commercially, for example, the Mobil
P-41 and P-51 esters of ExxonMobil Chemical Company).
[0030] Other useful fluids of lubricating viscosity include
non-conventional or unconventional base stocks that have been
processed, preferably catalytically, or synthesized to provide high
performance lubrication characteristics.
[0031] Non-conventional or unconventional base stocks/base oils
include one or more of a mixture of base stock(s) derived from one
or more Gas-to-Liquids (GTL) materials, as well as
isomerate/isodewaxate base stock(s) derived from natural wax or
waxy feeds, mineral and or non-mineral oil waxy feed stocks such as
slack waxes, natural waxes, and waxy stocks such as gas oils, waxy
fuels hydrocracker bottoms, waxy raffinate, hydrocrackate, thermal
crackates, or other mineral, mineral oil, or even non-petroleum oil
derived waxy materials such as waxy materials received from coal
liquefaction or shale oil, and mixtures of such base stocks.
[0032] GTL materials are materials that are derived via one or more
synthesis, combination, transformation, rearrangement, and/or
degradation/deconstructive processes from gaseous carbon-containing
compounds, hydrogen-containing compounds and/or elements as feed
stocks such as hydrogen, carbon dioxide, carbon monoxide, water,
methane, ethane, ethylene, acetylene, propane, propylene, propyne,
butane, butylenes, and butynes. GTL base stocks and/or base oils
are GTL materials of lubricating viscosity that are generally
derived from hydrocarbons; for example, waxy synthesized
hydrocarbons, that are themselves derived from simpler gaseous
carbon-containing compounds, hydrogen-containing compounds and/or
elements as feed stocks. GTL base stock(s) and/or base oil(s)
include oils boiling in the lube oil boiling range (1)
separated/fractionated from synthesized GTL materials such as, for
example, by distillation and subsequently subjected to a final wax
processing step which involves either or both of a catalytic
dewaxing process, or a solvent dewaxing process, to produce lube
oils of reduced/low pour point; (2) synthesized wax isomerates,
comprising, for example, hydrodewaxed or hydroisomerized cat and/or
solvent dewaxed synthesized wax or waxy hydrocarbons; (3)
hydrodewaxed or hydroisomerized cat and/or solvent dewaxed
Fischer-Tropsch (F-T) material (i.e., hydrocarbons, waxy
hydrocarbons, waxes and possible analogous oxygenates); preferably
hydrodewaxed or hydroisomerized/followed by cat and/or solvent
dewaxing dewaxed F-T waxy hydrocarbons, or hydrodewaxed or
hydroisomerized/followed by cat (or solvent) dewaxing dewaxed, F-T
waxes, or mixtures thereof.
[0033] GTL base stock(s) and/or base oil(s) derived from GTL
materials, especially, hydrodewaxed or hydroisomerized/followed by
cat and/or solvent dewaxed wax or waxy feed, preferably F-T
material derived base stock(s) and/or base oil(s), are
characterized typically as having kinematic viscosities at
100.degree. C. of from 2 mm.sup.2/s to 50 mm.sup.2/s (ASTM D445).
They are further characterized typically as having pour points of
-5.degree. C. to -40.degree. C. or lower (ASTM D97). They are also
characterized typically as having viscosity indices of 80 to 140 or
greater (ASTM D2270).
[0034] In addition, the GTL base stock(s) and/or base oil(s) are
typically highly paraffinic (>90% saturates), and may contain
mixtures of monocycloparaffins and multicycloparaffins in
combination with non-cyclic isoparaffins. The ratio of the
naphthenic (i.e., cycloparaffin) content in such combinations
varies with the catalyst and temperature used. Further, GTL base
stock(s) and/or base oil(s) typically have very low sulfur and
nitrogen content, generally containing less than 10 ppm, and more
typically less than 5 ppm of each of these elements. The sulfur and
nitrogen content of GTL base stock(s) and/or base oil(s) obtained
from F-T material, especially F-T wax, is essentially nil. In
addition, the absence of phosphorous and aromatics make this
materially especially suitable for the formulation of low SAP
products.
[0035] The term GTL base stock and/or base oil and/or wax isomerate
base stock and/or base oil is to be understood as embracing
individual fractions of such materials of wide viscosity range as
recovered in the production process, mixtures of two or more of
such fractions, as well as mixtures of one or two or more low
viscosity fractions with one, two or more higher viscosity
fractions to produce a blend wherein the blend exhibits a target
kinematic viscosity.
[0036] The GTL material, from which the GTL base stock(s) and/or
base oil(s) is/are derived is preferably an F-T material (i.e.,
hydrocarbons, waxy hydrocarbons, wax).
[0037] In addition, the GTL base stock(s) and/or base oil(s) are
typically highly paraffinic (>90% saturates), and may contain
mixtures of monocycloparaffins and multicycloparaffins in
combination with non-cyclic isoparaffins. The ratio of the
naphthenic (i.e., cycloparaffin) content in such combinations
varies with the catalyst and temperature used. Further, GTL base
stock(s) and/or base oil(s) and hydrodewaxed, or
hydroisomerized/cat (and/or solvent) dewaxed base stock(s) and/or
base oil(s) typically have very low sulfur and nitrogen content,
generally containing less than 10 ppm, and more typically less than
5 ppm of each of these elements. The sulfur and nitrogen content of
GTL base stock(s) and/or base oil(s) obtained from F-T material,
especially F-T wax, is essentially nil. In addition, the absence of
phosphorous and aromatics make this material especially suitable
for the formulation of low sulfur, sulfated ash, and phosphorus
(low SAP) products.
[0038] Base oils for use in the formulated lubricating oils useful
in the present disclosure are any of the variety of oils
corresponding to API Group I, Group II, Group III, Group IV, and
Group V oils and mixtures thereof, preferably API Group II, Group
III, Group IV, and Group V oils and mixtures thereof, more
preferably the Group III to Group V base oils due to their
exceptional volatility, stability, viscometric and cleanliness
features. Minor quantities of Group I stock, such as the amount
used to dilute additives for blending into formulated lube oil
products, can be tolerated but should be kept to a minimum, i.e.
amounts only associated with their use as diluent/carrier oil for
additives used on an "as-received" basis. Even in regard to the
Group II stocks, it is preferred that the Group II stock be in the
higher quality range associated with that stock, i.e. a Group II
stock having a viscosity index in the range 100<VI<120.
[0039] The base oil constitutes the major component of the engine
oil lubricant composition of the present disclosure and typically
is present in an amount ranging from 50 to 99 weight percent,
preferably from 70 to 95 weight percent, and more preferably from
85 to 95 weight percent, based on the total weight of the
composition. The base oil may be selected from any of the synthetic
or natural oils typically used as crankcase lubricating oils for
spark-ignited and compression-ignited engines. The base oil
conveniently has a kinematic viscosity, according to ASTM
standards, of 2.5 cSt to 12 cSt (or mm.sup.2/s) at 100.degree. C.
and preferably of 2.5 cSt to 9 cSt (or mm.sup.2/s) at 100.degree.
C. Mixtures of synthetic and natural base oils may be used if
desired.
Antiwear Additive
[0040] A metal alkylthiophosphate and more particularly a metal
dialkyl dithio phosphate in which the metal constituent is zinc, or
zinc dialkyl dithio phosphate (ZDDP) is an essential component of
the lubricating oils of this disclosure. ZDDP can be primary,
secondary or mixtures thereof. ZDDP compounds generally are of the
formula Zn[SP(S)(OR.sup.1)(OR.sup.2)].sub.2 where R.sup.1 and
R.sup.2 are C.sub.1-C.sub.18 alkyl groups, preferably
C.sub.2-C.sub.12 alkyl groups. These alkyl groups may be straight
chain or branched.
[0041] Preferable zinc dithiophosphates which are commercially
available include secondary zinc dithiophosphates such as those
available from for example, The Lubrizol Corporation under the
trade designations "LZ 677A", "LZ 1095" and "LZ 1371", from for
example Chevron Oronite under the trade designation "OLOA 262" and
from for example Afton Chemical under the trade designation "HITEC
7169".
[0042] The ZDDP is typically used in amounts of from 0.4 weight
percent to 1.2 weight percent, preferably from 0.5 weight percent
to 1.0 weight percent, and more preferably from 0.6 weight percent
to 0.8 weight percent, based on the total weight of the lubricating
oil, although more or less can often be used advantageously.
Preferably, the ZDDP is a secondary ZDDP and present in an amount
of from 0.6 to 1.0 weight percent of the total weight of the
lubricating oil.
Detergent Mixture Additive
[0043] A detergent mixture containing (i) at least two alkali metal
detergents, (ii) at least two alkaline earth metal detergents, or
(iii) one or more alkali metal detergents and one or more alkaline
earth metal detergents, is an essential component in the
lubricating oils of this disclosure. A typical detergent is an
anionic material that contains a long chain hydrophobic portion of
the molecule and a smaller anionic or oleophobic hydrophilic
portion of the molecule. The anionic portion of the detergent is
typically derived from an organic acid such as a sulfur acid,
carboxylic acid, phosphorous acid, phenol, or mixtures thereof. The
counterion is typically an alkaline earth or alkali metal.
[0044] Salts that contain a substantially stoichiometric amount of
the metal are described as neutral salts and have a total base
number (TBN, as measured by ASTM D2896) of from 0 to 80. Many
compositions are overbased, containing large amounts of a metal
base that is achieved by reacting an excess of a metal compound (a
metal hydroxide or oxide, for example) rich an acidic gas (such as
carbon dioxide). Useful detergents can be neutral, mildly
overbased, or highly overbased.
[0045] It is desirable for at least some detergent used in the
detergent mixture to be overbased. Overbased detergents help
neutralize acidic impurities produced by the combustion process and
become entrapped in the oil. Typically, the overbased material has
a ratio of metallic ion to anionic portion of the detergent of
1.05:1 to 50:1 on an equivalent basis. More preferably, the ratio
is from 4:1 to 25:1. The resulting detergent is an overbased
detergent that will typically have a TBN of 150 or higher, often
250 to 450 or more. Preferably, the overbasing cation is sodium,
calcium, or magnesium. A mixture of detergents of differing TBN can
be used in the present disclosure.
[0046] Preferred detergent mixtures include at least two of the
alkali or alkaline earth metal salts of sulfonates, phenates,
carboxylates, phosphates, and salicylates, e.g., a mixture of
magnesium sulfonate and calcium salicylate.
[0047] Sulfonates may be prepared from sulfonic acids that are
typically obtained by sulfonation of alkyl substituted aromatic
hydrocarbons. Hydrocarbon examples include those obtained by
alkylating benzene, toluene, xylene, naphthalene, biphenyl and
their halogenated derivatives (chlorobenzme, chlorotoluene, and
chloronaphthalene, for example). The alkylating agents typically
have 3 to 70 carbon atoms. The alkaryl sulfonates typically contain
9 to 80 carbon or more carbon atoms, more typically from 16 to 60
carbon atoms.
[0048] Alkaline earth phenates are another useful class of
detergent. These detergents can be made by reacting alkaline earth
metal hydroxide or oxide (CaO, Ca(OH).sub.2, BaO, Ba(OH).sub.2,
MgO, Mg(OH).sub.2, for example) with an alkyl phenol or sulfurized
alkylphenol. Useful alkyl groups include straight chain or branched
C.sub.1-C.sub.30 alkyl groups, preferably, C.sub.4-C.sub.20.
Examples of suitable phenols include isobutylphenol,
2-ethylhexylphenol, nonylphenol, dodecyl phenol, and the like. It
should be noted that starting alkylphenols may contain more than
one alkyl substituent that are each independently straight chain or
branched. When a non-sulfurized alkylphenol is used, the sulfurized
product may be obtained by methods well known in the art. These
methods include heating a mixture of alkylphenol and sulfurizing
agent (including elemental sulfur, sulfur halides such as sulfur
dichloride, and the like) and then reacting the sulfurized phenol
with an alkaline earth metal base.
[0049] Metal salts of carboxylic acids are also useful as
detergents. These carboxylic acid detergents may be prepared by
reacting a basic metal compound with at least one carboxylic acid
and removing free water from the reaction product. These compounds
may be overbased to produce the desired TBN level. Detergents made
from salicylic acid are one preferred class of detergents derived
from carboxylic acids. Useful salicylates include long chain alkyl
salicylates. One useful family of compositions is of the
formula
##STR00001##
where R is an alkyl group having 1 to 30 carbon atoms, n is an
integer from 1 to 4, and M is an alkaline earth metal. Preferred R
groups are alkyl chains of at least C.sub.11, preferably C.sub.13
or greater. R may be optionally substituted with substituents that
do not interfere with the detergent's function, M is preferably,
calcium, magnesium, or barium. More preferably, M is calcium.
[0050] Hydrocarbyl-substituted salicylic acids may be prepared from
phenols by the Kolbe reaction (see U.S. Pat. No. 3,595,791). The
metal salts of the hydrocarbyl-substituted salicylic acids may be
prepared by double decomposition of a metal salt in a polar solvent
such as water or alcohol.
[0051] Alkaline earth metal phosphates are also used as detergents
and are known in the art.
[0052] Detergents may be simple detergents or what is known as
hybrid or complex detergents. The latter detergents can provide the
properties of two detergents without the need to blend separate
materials. See U.S. Pat. No. 6,034,039.
[0053] Preferred detergent mixtures include at least two of calcium
phenates, calcium sulfonates, calcium salicylates, magnesium
phenates, magnesium sulfonates, magnesium salicylates and other
related components (including borated detergents) in any
combination. A preferred detergent mixture includes magnesium
sulfonate and calcium salicylate.
[0054] The detergent mixture concentration in the lubricating oils
of this disclosure can range from 1.0 to 6.0 weight percent,
preferably 2.0 to 5.0 weight percent, and more preferably from 2.0
weight percent to 4.0 weight percent, based on the total weight of
the lubricating oil.
Other Additives
[0055] The formulated lubricating oil useful in the present
disclosure may additionally contain one or more of the other
commonly used lubricating oil performance additives including but
not limited to dispersants, other detergents, corrosion inhibitors,
rust inhibitors, metal deactivators, other anti-wear agents and/or
extreme pressure additives, anti-seizure agents, wax modifiers,
viscosity index improvers, viscosity modifiers, fluid-loss
additives, seal compatibility agents, friction modifiers, lubricity
agents, anti-staining agents, chromophoric agents, defoamants,
demulsifiers, emulsifiers, densifiers, wetting agents, gelling
agents, tackiness agents, colorants, and others. For a review of
many commonly used additives, see Klamann in Lubricants and Related
Products, Verlag Chemie, Deerfield Beach, Fla.; ISBN 0-89573-177-0.
Reference is also made to "Lubricant Additives" by M. W. Ranney,
published by Noyes Data Corporation of Parkridge, N.J. (1973).
[0056] The types and quantities of performance additives used in
combination with the instant disclosure in lubricant compositions
are not limited by the examples shown herein as illustrations.
Dispersants
[0057] During engine operation, oil-insoluble oxidation byproducts
are produced. Dispersants help keep these byproducts in solution,
thus diminishing their deposition on metal surfaces. Dispersants
used in the formulation of the lubricating oil may be ashless or
ash-forming in nature. Preferably, the dispersant is ashless.
So-called ashless dispersants are organic materials that form
substantially no ash upon combustion. For example,
non-metal-containing or borated metal-free dispersants are
considered ashless. In contrast, metal-containing detergents
discussed above form ash upon combustion.
[0058] Suitable dispersants typically contain a polar group
attached to a relatively high molecular weight hydrocarbon chain.
The polar group typically contains at least one element of
nitrogen, oxygen, or phosphorus. Typical hydrocarbon chains contain
50 to 400 carbon atoms.
[0059] Chemically, many dispersants may be characterized as
phenates, sulfonates, sulfurized phenates, salicylates,
naphthenates, stearates, carbamates, thiocarbamates, phosphorus
derivatives. A particularly useful class of dispersants are the
alkenylsuccinic derivatives, typically produced by the reaction of
a long chain hydrocarbyl substituted succinic compound, usually a
hydrocarbyl substituted succinic anhydride, with a polyhydroxy or
polyamino compound. The long chain hydrocarbyl group constituting
the oleophilic portion of the molecule which confers solubility in
the oil, is normally a polyisobutylene group. Many examples of this
type of dispersant are well known commercially and in the
literature. Exemplary U.S. patents describing such dispersants are
U.S. Pat. Nos. 3,172,892; 3,215,707; 3,219,666; 3,316,177;
3,341,542; 3,444,170; 3,454,607; 3,541,012; 3,630,904; 3,632,511;
3,787,374 and 4,234,435. Other types of dispersant are described in
U.S. Pat. Nos. 3,036,003; 3,200,107; 3,254,025; 3,275,554;
3,438,757; 3,454,555; 3,565,804; 3,413,347; 3,697,574; 3,725,277;
3,725,480; 3,726,882; 4,454,059; 3,329,658; 3,449,250; 3,519,565;
3,666,730; 3,687,849; 3,702,300; 4,100,082; 5,705,458. A further
description of dispersants may be found, for example, in European
Patent Application No, 471 071, to which reference is made for this
purpose.
[0060] Hydrocarbyl-substituted succinic acid and
hydrocarbyl-substituted succinic anhydride derivatives are useful
dispersants. In particular, succinimide, succinate esters, or
succinate ester amides prepared by the reaction of a
hydrocarbon-substituted succinic acid compound preferably having at
least 50 carbon atoms in the hydrocarbon substituent, with at least
one equivalent of an alkylene amine are particularly useful.
[0061] Succinimides are formed by the condensation reaction between
hydrocarbyl substituted succinic anhydrides and amines. Molar
ratios can vary depending on the polyamine. For example, the molar
ratio of hydrocarbyl substituted succinic anhydride to TEPA can
vary from 1:1 to 5:1. Representative examples are shown in U.S.
Pat. Nos. 3,087,936; 3,172,892; 3,219,666; 3,272,746; 3,322,670;
and 3,652,616, 3,948,800; and Canada Patent No. 1,094,044.
[0062] Succinate esters are formed by the condensation reaction
between hydrocarbyl substituted succinic anhydrides and alcohols or
polyols. Molar ratios can vary depending on the alcohol or polyol
used. For example, the condensation product of a hydrocarbyl
substituted succinic anhydride and pentaerythritol is a useful
dispersant.
[0063] Succinate ester amides are formed by condensation reaction
between hydrocarbyl substituted succinic anhydrides and alkanol
amines. For example, suitable alkanol amines include ethoxylated
polyalkylpolyamines, propoxylated polyalkylpolyamines and
polyalkenylpolyamines such as polyethylene polyamines. One example
is propoxylated hexamethylenediamine. Representative examples are
shown in U.S. Pat. No. 4,426,305.
[0064] The molecular weight of the hydrocarbyl substituted succinic
anhydrides used in the preceding paragraphs will typically range
between 800 and 2,500. The above products can be post-reacted with
various reagents such as sulfur, oxygen, formaldehyde, carboxylic
acids such as oleic acid. The above products can also be post
reacted with boron compounds such as boric acid, borate esters or
highly borated dispersants, to form borated dispersants generally
having from 0.1 to 5 moles of boron per mole of dispersant reaction
product.
[0065] Mannich base dispersants are made from the reaction of
alkylphenols, formaldehyde, and amines. See U.S. Pat. No.
4,767,551, which is incorporated herein by reference. Process aids
and catalysts, such as oleic acid and sulfonic acids, can also be
part of the reaction mixture. Molecular weights of the alkylphenols
range from 800 to 2,500. Representative examples are shown in U.S.
Pat. Nos. 3,697,574; 3,703,536; 3,704,308; 3,751,365; 3,756,953;
3,798,165; and 3,803,039.
[0066] Typical high molecular weight aliphatic acid modified
Mannich condensation products useful in this disclosure can be
prepared from high molecular weight alkyl-substituted
hydroxyaromatics or HN(R).sub.2 group-containing reactants.
[0067] Hydrocarbyl substituted amine ashless dispersant additives
are well known to one skilled in the art; see, for example, U.S.
Pat. Nos. 3,275,554; 3,438,757; 3,565,804; 3,755,433, 3,822,209,
and 5,084,197.
[0068] Preferred dispersants include borated and non-borated
succinimides, including those derivatives from mono-succinimides,
bis-succinimides, and/or mixtures of mono- and bis-succinimides,
wherein the hydrocarbyl succinimide is derived from a
hydrocarbylene group such as polyisobutylene having a Mn of from
500 to 5000 or a mixture of such hydrocarbylene groups. Other
preferred dispersants include succinic acid-esters and amides,
alkylphenol-polyamine-coupled Mannich adducts, their capped
derivatives, and other related components. Such additives may be
used in an amount of 0.1 to 20 weight percent, preferably 0.5 to 8
weight percent.
Antioxidants
[0069] Antioxidants retard the oxidative degradation of base oils
during service. Such degradation may result in deposits on metal
surfaces, the presence of sludge, or a viscosity increase in the
lubricant. One skilled in the art knows a wide variety of oxidation
inhibitors that are useful in lubricating oil compositions. See,
Klamann in Lubricants and Related Products, op cite, and U.S. Pat.
Nos. 4,798,684 and 5,084,197, for example.
[0070] Useful antioxidants include hindered phenols. These phenolic
antioxidants may be ashless (metal-free) phenolic compounds or
neutral or basic metal salts of certain phenolic compounds. Typical
phenolic antioxidant compounds are the hindered phenolics which are
the ones which contain a sterically hindered hydroxyl group, and
these include those derivatives of dihydroxy aryl compounds in
which the hydroxyl groups are in the o- or p-position to each
other. Typical phenolic antioxidants include the hindered phenols
substituted with C.sub.6+ alkyl groups and the alkylene coupled
derivatives of these hindered phenols. Examples of phenolic
materials of this type 2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl
phenol; 2-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol;
2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-heptyl
phenol; and 2-methyl-6-t-butyl-4-dodecyl phenol. Other useful
hindered mono-phenolic antioxidants may include for example
hindered 2,6-di-alkyl-phenolic proprionic ester derivatives.
Bis-phenolic antioxidants may also be advantageously used in
combination with the instant disclosure. Examples of ortho-coupled
phenols include: 2,2'-bis(4-heptyl-6-t-butyl-phenol);
2,2'-bis(4-octyl-6-t-butyl-phenol); and
2,2'-bis(4-dodecyl-6-t-butyl-phenol). Para-coupled bisphenols
include for example 4, 4'-bis(2,6-di-t-butyl phenol) and
4,4'-methylene-bis(2,6-di-t-butyl phenol).
[0071] Non-phenolic oxidation inhibitors which may be used include
aromatic amine antioxidants and these may be used either as such or
in combination with phenolics. Typical examples of non-phenolic
antioxidants include: alkylated and non-alkylated aromatic amines
such as aromatic monoamines of the formula R.sup.8R.sup.9R.sup.10N
where R.sup.8 is an aliphatic, aromatic or substituted aromatic
group, R.sup.9 is an aromatic or a substituted aromatic group, and
R.sup.10 is H, alkyl, aryl or R.sup.11S(O).sub.xR.sup.12 where
R.sup.11 is an alkylene, alkenylene, or aralkylene group, R.sup.12
is a higher alkyl group, or an alkenyl, aryl, or alkaryl group, and
x is 0, 1 or 2. The aliphatic group R.sup.8 may contain from 1 to
20 carbon atoms, and preferably contains from 6 to 12 carbon atoms.
The aliphatic group is a saturated aliphatic group. Preferably,
both R.sup.8 and R.sup.9 are aromatic or substituted aromatic
groups, and the aromatic group may be a fused ring aromatic group
such as naphthyl. Aromatic groups R.sup.8 and R.sup.9 may be joined
together with other groups such as S.
[0072] Typical aromatic amines antioxidants have alkyl substituent
groups of at least 6 carbon atoms. Examples of aliphatic groups
include hexyl, heptyl, octyl, nonyl, and decyl. Generally, the
aliphatic groups will not contain more than 14 carbon atoms. The
general types of amine antioxidants useful in the present
compositions include diphenylamines, phenyl naphthylamines,
phenothiazines, imidodibenzyls and diphenyl phenylene diamines.
Mixtures of two or more aromatic amines are also useful. Polymeric
amine antioxidants can also be used. Particular examples of
aromatic amine antioxidants useful in the present disclosure
include: p,p'-dioctyldiphenylamine;
t-octylphenyl-alpha-naphthylamine; phenyl-alphanaphthylamine; and
p-octylphenyl-alpha-naphthylamine.
[0073] Sulfurized alkyl phenols and alkali or alkaline earth metal
salts thereof also are useful antioxidants.
[0074] Preferred antioxidants include hindered phenols, arylamines.
These antioxidants may be used individually by type or in
combination with one another. Such additives may be used in an
amount of 0.01 to 5 weight percent, preferably 0.01 to 1.5 weight
percent, more preferably zero to less than 1.5 weight percent, most
preferably zero.
Pour Point Depressants (PPDs)
[0075] Conventional pour point depressants (also known as lube oil
flow improvers) may be added to the compositions of the present
disclosure if desired. These pour point depressant may be added to
lubricating compositions of the present disclosure to lower the
minimum temperature at which the fluid will flow or can be poured.
Examples of suitable pour point depressants include
polymethacrylates, polyacrylates, polyarylamides, condensation
products of haloparaffin waxes and aromatic compounds, vinyl
carboxylate polymers, and terpolymers of dialkylfumarates, vinyl
esters of fatty acids and allyl vinyl ethers. U.S. Pat. Nos.
1,815,022; 2,015,748; 2,191,498; 2,387,501; 2,655,479; 2,666,746;
2,721,877; 2,721,878; and 3,250,715 describe useful pour point
depressants and/or the preparation thereof. Such additives may be
used in an amount of 0.01 to 5 weight percent, preferably 0.01 to
1.5 weight percent.
Seal Compatibility Agents
[0076] Seal compatibility agents help to swell elastomeric seals by
causing a chemical reaction in the fluid or physical change in the
elastomer. Suitable seal compatibility agents for lubricating oils
include organic phosphates, aromatic esters, aromatic hydrocarbons,
esters (butylbenzyl phthalate, for example), and polybutenyl
succinic anhydride. Such additives may be used in an amount of 0.01
to 3 weight percent, preferably 0.01 to 2 weight percent.
Anti-Foam Agents
[0077] Anti-foam agents may advantageously be added to lubricant
compositions. These agents retard the formation of stable foams.
Silicones and organic polymers are typical anti-foam agents. For
example, polysiloxanes, such as silicon oil or polydimethyl
siloxane, provide antifoam properties. Anti-foam agents are
commercially available and may be used in conventional minor
amounts along with other additives such as demulsifiers; usually
the amount of these additives combined is less than 1 weight
percent and often less than 0.1 weight percent.
Friction Modifiers
[0078] A friction modifier is any material or materials that can
alter the coefficient of friction of a surface lubricated by any
lubricant or fluid containing such material(s). Friction modifiers,
also known as friction reducers, or lubricity agents or oiliness
agents, and other such agents that change the ability of base oils,
formulated lubricant compositions, or functional fluids, to modify
the coefficient of friction of a lubricated surface may be
effectively used in combination with the base oils or lubricant
compositions of the present disclosure if desired. Friction
modifiers that lower the coefficient of friction are particularly
advantageous in combination with the base oils and lube
compositions of this disclosure. Friction modifiers may include
metal-containing compounds or materials as well as ashless
compounds or materials, or mixtures thereof. Metal-containing
friction modifiers may include metal salts or metalligand complexes
where the metals may include alkali, alkaline earth, or transition
group metals. Such metal-containing friction modifiers may also
have low-ash characteristics. Transition metals may include Mo, Sb,
Sn, Fe, Cu, Zn, and others. Ligands may include hydrocarbyl
derivative of alcohols, polyols, glycerols, partial ester
glycerols, thiols, carboxylates, carbamates, thiocarbamates,
dithiocarbamates, phosphates, thiophosphates, dithiophosphates,
amides, imides, amines, thiazoles, thiadiazoles, dithiazoles,
diazoles, triazoles, and other polar molecular functional groups
containing effective amounts of O, N, S, or P, individually or in
combination. In particular, Mo-containing compounds can be
particularly effective such as for example Mo-dithiocarbamates,
Mo(DTC), Mo-dithiophosphates, Mo(DTP), Mo-amines, Mo (Am),
Mo-alcoholates, Mo-alcohol-amides, etc. See U.S. Pat. Nos.
5,824,627, 6,232,276, 6,153,564, 6,143,701, 6,110,878, 5,837,657,
6,010,987, 5,906,968, 6,734,150, 6,730,638, 6,689,725, 6,569,820;
WO 99/66013; WO 99/47629; and WO 98/26030.
[0079] Ashless friction modifiers may also include lubricant
materials that contain effective amounts of polar groups, for
example, hydroxyl-containing hydrocarbyl base oils, glycerides,
partial glycerides, glyceride derivatives, and the like. Polar
groups in friction modifiers may include hydrocarbyl groups
containing effective amounts of O, N, S, or P, individually or in
combination. Other friction modifiers that may be particularly
effective include, for example, salts (both ash-containing and
ashless derivatives) of fatty acids, fatty alcohols, fatty amides,
fatty esters, hydroxyl-containing carboxylates, and comparable
synthetic long-chain hydrocarbyl acids, alcohols, amides, esters,
hydroxy carboxylates, and the like. In some instances fatty organic
acids, fatty amines, and sulfurized fatty acids may be used as
suitable friction modifiers.
[0080] Useful concentrations of friction modifiers may range from
0.01 weight percent to 10-15 weight percent or more, often with a
preferred range of 0.1 weight percent to 5 weight percent.
Concentrations of molybdenum-containing materials are often
described in terms of Mo metal concentration. Advantageous
concentrations of Mo may range from 10 ppm to 3000 ppm or more, and
often with a preferred range of 20-2000 ppm, and in some instances
a more preferred range of 30-1000 ppm. Friction modifiers of all
types may be used alone or in mixtures with the materials of this
disclosure. Often mixtures of two or more friction modifiers, or
mixtures of friction modifier(s) with alternate surface active
material(s), are also desirable.
Viscosity Index Improvers
[0081] Viscosity index improvers (also known as VI improvers,
viscosity modifiers, and viscosity improvers) can be included in
the lubricant compositions of this disclosure. Preferably, the
method of this disclosure obtains improvements in fuel economy
without sacrificing durability by a reduction of high-temperature
high-shear (HTHS) viscosity to a level lower than 2.6 cP through
reduction or removal of viscosity index improvers or modifiers.
[0082] Viscosity index improvers provide lubricants with high and
low temperature operability. These additives impart shear stability
at elevated temperatures and acceptable viscosity at low
temperatures.
[0083] Suitable viscosity index improvers include high molecular
weight hydrocarbons, polyesters and viscosity index improver
dispersants that function as both a viscosity index improver and a
dispersant. Typical molecular weights of these polymers are between
10,000 to 1,500,000, more typically 20,000 to 1,200,000, and even
more typically between 50,000 and 1,000,000.
[0084] Examples of suitable viscosity index improvers are linear or
star-shaped polymers and copolymers of methacrylate, butadiene,
olefins, or alkylated styrenes. Polyisobutylene is a commonly used
viscosity index improver. Another suitable viscosity index improver
is polymethacrylate (copolymers of various chain length alkyl
methacrylates, for example), some formulations of which also serve
as pour point depressants. Other suitable viscosity index improvers
include copolymers of ethylene and propylene, hydrogenated block
copolymers of styrene and isoprene, and polyacrylates (copolymers
of various chain length acrylates, for example). Specific examples
include styrene-isoprene or styrene-butadiene based polymers of
50,000 to 200,000 molecular weight.
[0085] Olefin copolymers, are commercially available from Chevron
Oronite Company LLC under the trade designation "PARATONE.RTM."
(such as "PARATONE.RTM. 8921" and "PARATONE.RTM. 8941"); from Afton
Chemical Corporation under the trade designation "HiTEC.RTM." (such
as "HiTEC.RTM. 5850B"; and from The Lubrizol Corporation under the
trade designation "Lubrizol.RTM. 7067C". Polyisoprene polymers are
commercially available from Infineum International Limited, e.g.
under the trade designation "SV200"; diene-styrene copolymers are
commercially available from Infineum International Limited, e.g.
under the trade designation "SV 260".
[0086] In an embodiment of this disclosure, the viscosity index
improvers may be used in an amount of less than 2.0 weight percent,
preferably less than 1.0 weight percent, and more preferably less
than 0.5 weight percent, based on the total weight of the
formulated oil or lubricating engine oil.
[0087] In another embodiment of this disclosure, the viscosity
index improvers may be used in an amount of from 0.0 to 2.0 weight
percent, preferably 0.0 to 1.0 weight percent, and more preferably
0.0 to 0.5 weight percent, based on the total weight of the
formulated oil or lubricating engine oil.
[0088] When lubricating oil compositions contain one or more of the
additives discussed above, the additive(s) are blended into the
composition in an amount sufficient for it to perform its intended
function. Typical amounts of such additives useful in the present
disclosure are shown in Table 1 below.
[0089] It is noted that many of the additives are shipped from the
additive manufacturer as a concentrate, containing one or more
additives together, with a certain amount of base oil diluent.
Accordingly, the weight amounts in the table below, as well as
other amounts mentioned in this specification, are directed to the
amount of active ingredient (that is the non-diluent portion of the
ingredient). The weight percent (wt %) indicated below is based on
the total weight of the lubricating oil composition.
TABLE-US-00002 TABLE 1 Typical Amounts of Other Lubricating Oil
Components Approximate Approximate Compound wt % (Useful) wt %
(Preferred) Dispersant 0.1-20 0.1-8 Friction Modifier 0.01-5
0.01-1.5 Antioxidant 0.1-5 0.1-1.5 Pour Point Depressant 0.0-5
0.01-1.5 (PPD) Anti-foam Agent 0.001-3 0.001-0.15 Viscosity Index
Improver 0.0-2 0.0-1 (solid polymer basis)
[0090] The foregoing additives are all commercially available
materials. These additives may be added independently but are
usually precombined in packages which can be obtained from
suppliers of lubricant oil additives. Additive packages with a
variety of ingredients, proportions and characteristics are
available and selection of the appropriate package will take the
requisite use of the ultimate composition into account.
[0091] The following non-limiting examples are provided to
illustrate the disclosure.
EXAMPLES
[0092] Representative formulations are given in Table 2.
TABLE-US-00003 TABLE 2 Formulation Comp. Ex. 1 Ex. 2 Ex. 3 Ex. 4
Ex. A Viscosity Grade Component, wt % 0W 0W 0W 5W 0W-20 Salicylate
and 2.73 2.73 3.52 * 2.73 Sulfonate Detergent Mixture ZDDP 0.734
0.734 .75 * 0.734 Viscosity Index 0.0 0.468 .12 0 0.702 Improver
Other Additives Balance Balance Balance * Balance (dispersant,
antioxidant, defoamant, PPD, seal swell agent, friction modifier)
Base Oil 88.886 88.42 87.46 88.9 88.184 Formulated Oil 5.7 7.7 6.0
6.1 8.8 KV@100 C., cSt Formulation Comp. Comp. Comp. Ex. B Ex. C
Ex. D Viscosity Grade Component, wt % 0W-20 5W-20 0W Salicylate and
3.52 * 2.73 Sulfonate Detergent Mixture ZDDP 0.75 * 0.734 Viscosity
index 0.561 0.315 0.78 improver Other Additives Balance * Balance
(dispersant, antioxidant, defoamant, PPD, seal swell agent,
friction modifier) Base oil 87.019 88.585 88.106 Formulated Oil 8.6
8.5 9.9 KV@100 C., cSt * 10.8 weight % of Lubrizol 20018
commercially available GF-4 additive package.
[0093] Among the features of the compositions of the disclosure is
that there has been demonstrated both unexpected combination of
wear and fuel efficiency performance. For instance, fuel economy
can be improved by at least 0.4% as measured in the M111 FE engine
test and while the wear performance is improved relative to the
comparison oils.
[0094] Performance evaluation of the formulations is given in
Tables 3-11. The following engine tests were performed to measure
wear and fuel economy of the engine oil lubricant composition of
the present disclosure: TU3M (CEC L-038-94), M111FE (CEC L-054-96),
Sequence IIIG (ASTM D7320), Sequence IVA (ASTM D6891), Sequence VID
(ASTM D7589), OM646LA (CEC L-099-08), Caterpillar 1M-PC (ASTM
D6618) and Sequence VIII (ASTM D6709); all of which are
incorporated herein by reference. HTHS viscosity was measured using
ASTM D4683 which is incorporated herein by reference.
TABLE-US-00004 TABLE 3 Comp. Comp. Comp. Description Ex. 1 Ex. 2
Ex. 3 Ex. 4 Ex. A Ex. B Ex. C Comp. Ex. D HTHS, 2.0 2.3 2.1 2.2 2.6
2.6 2.6 2.6 cP at 150.degree. C. Viscosity Grade 0 W 0 W 0 W 5 W 0
W-20 0 W-20 5 W-20 0 W Engine Test Parameter TU3M Valve Train
Scuffing Wear Average cam 3.6 -- 7.0 3.0 6.4 4.8 -- -- wear, .mu.m
Maximum 4.5 -- 9.5 5.0 9.9 10.9 -- -- cam wear, .mu.m Pad rating
8.3 -- 8.8 8.9 8.6 8.6 -- -- (average of 8), merits
[0095] The parameters listed in Table 3 above, and methods for
determining same, are more fully described in CEC L-038-94.
TABLE-US-00005 TABLE 4 Comp. Comp. Comp. Comp. Description Ex. 1
Ex. 2 Ex. 3 Ex. 4 Ex. A Ex. B Ex. C Ex. D HTHS, 2.0 2.3 2.1 2.2 2.6
2.6 2.6 2.6 cP at 150.degree. C. Viscosity Grade 0 W 0 W 0 W 5 W 0
W-20 0 W-20 5 W-20 0 W Engine Test Parameter M111FE Fuel Economy
Fuel 3.77/4.01 3.91/3.69 -- -- -- -- -- 3.22/3.31 economy
improvement vs. RL 191
[0096] The parameters listed in Table 4 above, and methods for
determining same, are more fully described in CEC-L-054-96.
TABLE-US-00006 TABLE 5 Comp. Comp. Comp. Comp. Description Ex. 1
Ex. 2 Ex. 3 Ex. 4 Ex. A Ex. B Ex. C Ex. D HTHS, 2.0 2.3 2.1 2.2 2.6
2.6 2.6 2.6 cP at 150.degree. C. Viscosity Grade 0 W 0 W 0 W 5 W 0
W-20 0 W-20 5 W-20 0 W Engine Test Parameter Sequence Wear and Oil
IIIG Thickness Kinematic 52.5 -- 51.4 126.0 50.0 41.4 121.8 --
viscosity increase at 40.degree. C., % Average 6.43 -- 5.17 3.77
4.45 5.4 3.76 -- weighted piston deposits, merits Hot stuck None --
None None None None None -- rings Average cam 15.8 -- 25.4 17.6
14.9 59 38.2 -- and lifter wear, .mu.m
[0097] The parameters listed in Table 5 above, and methods for
determining same, are more fully described in ASTM D7320.
TABLE-US-00007 TABLE 6 Comp. Comp. Comp. Comp. Description Ex. 1
Ex. 2 Ex. 3 Ex. 4 Ex. A Ex. B Ex. C Ex. D HTHS, 2.0 2.3 2.1 2.2 2.6
2.6 2.6 2.6 cP at 150.degree. C. Viscosity Grade 0 W 0 W 0 W 5 W 0
W-20 0 W-20 5 W-20 0 W Engine Test Parameter Sequence Valvetrain
IVA Wear Average cam 11 -- -- -- 12 -- -- -- wear (7 point
average), .mu.m
[0098] The parameters listed in Table 6 above, and methods for
determining same, are more fully described in ASTM D6891.
TABLE-US-00008 TABLE 7 Comp. Comp. Comp. Comp. Description Ex. 1
Ex. 2 Ex. 3 Ex. 4 Ex. A Ex. B Ex. C Ex. D HTHS, 2.0 2.3 2.1 2.2 2.6
2.6 2.6 2.6 cP at 150.degree. C. Viscosity Grade 0 W 0 W 0 W 5 W 0
W-20 0 W-20 5 W-20 0 W Engine Test Parameter Sequence VID (modified
Fuel test) Economy FEI, SUM 2.30 2.18 -- -- -- -- -- 2.06 FEI 2
after 1.10 .85 -- -- -- -- -- 0.99 100 hours aging, % FEI 1 after
1.20 1.33 -- -- -- -- -- 1.07 16 hours aging, %
[0099] The parameters listed in Table 7 above, and methods for
determining same, are more fully described in ASTM D7589. In this
case a slightly modified version of ASTM D7589 was run; two
additional samples were taken during the test compared to the ASTM
method.
TABLE-US-00009 TABLE 8 Comp. Comp. Comp. Comp. Description Ex. 1
Ex. 2 Ex. 3 Ex. 4 Ex. A Ex. B Ex. C Ex. D HTHS, 2.0 2.3 2.1 2.2 2.6
2.6 2.6 2.6 cP at 150.degree. C. Viscosity Grade 0 W 0 W 0 W 5 W 0
W-20 0 W-20 5 W-20 0 W Engine Test Parameter OM646LA Wear -- -- --
Main bearing 0.2 -- -- -- 0.2 wear, .mu.m Conrod 0.0 0.2 bearing
wear, .mu.m Axial piston 11.0 8.6 ring wear, (1.sup.st ring), .mu.m
Axial piston 0.4 0.8 ring wear, (2.sup.nd ring), .mu.m Axial piston
1.7 1.2 ring wear, (3.sup.rd ring), .mu.m Radial piston 9.5 6.8
ring wear, (1.sup.st ring), .mu.m Radial piston 2.4 7.9 ring wear,
(2.sup.nd ring), .mu.m Radial piston 4.0 6.7 ring wear, (3.sup.rd
ring), .mu.m Cam wear 67.4 89.7 outlet (ave. max wear 8 cams),
.mu.m Cam wear 74.0 71.4 inlet (ave. max wear 8 cams), .mu.m
Cylinder 2.8 2.9 wear (ave. 4 cylinders), .mu.m Timing chain 0.2
0.2 elongation, % Bore 0.0 1.3 polishing (max.), % Tappet wear 5.4
8.9 inlet Tappet wear 8.0 9.7 outlet Ring sticking none None (max.)
Oil 6245 6185 consumption, g Viscosity 60.3 30.5 increase
@100.degree. C., % Soot, % 5.6 5.1 Piston 15.5 10.2 cleanliness,
merits Average 9.03 9.2 engine, sludge, merits
[0100] The parameters listed in Table 8 above, and methods for
determining same, are more fully described in CEC L-099-08.
TABLE-US-00010 TABLE 9 Comp. Comp. Comp. Comp. Description Ex. 1
Ex. 2 Ex. 3 Ex. 4 Ex. A Ex. B Ex. C Ex. D HTHS, 2.0 2.3 2.1 2.2 2.6
2.6 2.6 2.6 cP at 150.degree. C. Viscosity Grade 0 W 0 W 0 W 5 W 0
W-20 0 W-20 5 W-20 0 W Engine Test Parameter Caterpillar Diesel 1M-
Deposit and PC Wear Top groove 37 -- -- -- 50 -- -- -- fill, %
Weighted 138.0 -- -- -- 145.1 -- -- -- total demerits Piston, ring
None -- -- -- None -- -- -- and liner scuffing Piston ring none --
-- -- none -- -- -- sticking
[0101] The parameters listed in Table 9 above, and methods for
determining same, are more fully described in ASTM D6618.
TABLE-US-00011 TABLE 10 Comp. Comp. Comp. Comp. Comp. Description
Ex. 1 Ex. 2 Ex. 3 Ex. A Ex. A Ex. B Ex. C Ex. D HTHS, 2.0 2.3 2.1
2.2 2.6 2.6 2.6 2.6 cP at 150.degree. C. Viscosity Grade 0 W 0 W 0
W 0 W 0 W-20 0 W-205 W 5 W-20 0 W Engine Test Parameter Sequence
Bearing VIII Corrosion Bearing 4.6 -- 11.9 3.0 -- -- 21.6 -- weight
loss, mg 10 hour 5.69 -- 6.13 6.12 -- -- 8.08 -- stripped viscosity
at 100.degree. C., cSt
[0102] The parameters listed in Table 10 above, and methods for
determining same, are more fully described in ASTM D6709.
[0103] As can be seen from the foregoing Tables, the composition of
the disclosure provided improved or equivalent antiwear properties
while providing a substantial improvement in fuel economy when
compared to the other oils identified. In the foregoing Tables, the
blanks for engine test properties indicate that no data was
available for that particular test.
* * * * *
References