U.S. patent application number 11/651185 was filed with the patent office on 2007-08-30 for low sulfur, low ash and low phosphorous lubricant additive and composition.
Invention is credited to William H. Buck, Douglas E. Deckman, L. Oscar Farng, Willie A. JR. Givens, Andrew G. Horodysky.
Application Number | 20070203030 11/651185 |
Document ID | / |
Family ID | 38288148 |
Filed Date | 2007-08-30 |
United States Patent
Application |
20070203030 |
Kind Code |
A1 |
Buck; William H. ; et
al. |
August 30, 2007 |
Low sulfur, low ash and low phosphorous lubricant additive and
composition
Abstract
A lubricating oil composition is disclosed. This composition,
comprises a lubricating oil basestock, an alkylated aromatic
additive of at least 0.01 and less than 20 weight percent of the
composition, a dispersant-detergent-inhibitor system of less than
15 percent weight percent of the composition, a zinc
dithiophosphate additive of at least 0.1 weight percent of the
composition and no more than 1.0 weight percent of the composition,
the composition having less than 630 PPM phosphorus, less than 710
PPM zinc, less than 5,000 PPM sulfur, less than 8 TBN, less than
1.0 weight percent ash. In a second embodiment, an additive
composition for lubricating oils is disclosed. In a third
embodiment, a method of obtain a favorable lubricating properties
is disclosed.
Inventors: |
Buck; William H.; (West
Chester, PA) ; Farng; L. Oscar; (Lawrenceville,
NJ) ; Deckman; Douglas E.; (Mullica Hill, NJ)
; Givens; Willie A. JR.; (Dumfries, VA) ;
Horodysky; Andrew G.; (Cherry Hill, NJ) |
Correspondence
Address: |
ExxonMobil Research and Engineering Company
P. O. Box 900
Annandale
NJ
08801-0900
US
|
Family ID: |
38288148 |
Appl. No.: |
11/651185 |
Filed: |
January 9, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60758840 |
Jan 13, 2006 |
|
|
|
Current U.S.
Class: |
508/162 ;
508/569 |
Current CPC
Class: |
C10N 2030/74 20200501;
C10N 2030/04 20130101; C10N 2030/41 20200501; C10M 2207/026
20130101; C10N 2030/45 20200501; C10N 2030/10 20130101; C10N
2030/43 20200501; C10N 2030/12 20130101; C10M 2207/2835 20130101;
C10M 2215/06 20130101; C10N 2010/04 20130101; C10M 2219/04
20130101; C10M 2219/086 20130101; C10M 2223/045 20130101; C10M
2207/34 20130101; C10N 2030/42 20200501; C10M 163/00 20130101; C10M
2203/1025 20130101; C10N 2010/12 20130101; C10N 2030/38 20200501;
C10M 2217/043 20130101; C10M 2205/0285 20130101; C10M 2207/2825
20130101; C10N 2040/25 20130101; C10N 2020/085 20200501; C10N
2030/02 20130101; C10M 2215/28 20130101; C10N 2020/013 20200501;
C10N 2030/52 20200501; C10N 2030/06 20130101; C10M 2203/06
20130101; C10M 2203/1025 20130101; C10N 2020/02 20130101; C10M
2215/28 20130101; C10N 2060/14 20130101; C10M 2203/1025 20130101;
C10N 2020/02 20130101; C10M 2215/28 20130101; C10N 2060/14
20130101 |
Class at
Publication: |
508/162 ;
508/569 |
International
Class: |
C10M 141/10 20060101
C10M141/10; C10M 135/28 20060101 C10M135/28 |
Claims
1. A composition, comprising, a. a lubricating oil basestock; b. an
alkylated aromatic additive of at least 0.01 and less than 20
weight percent of the composition; c. a
dispersant-detergent-inhibitor system of less than 15 weight
percent of the composition; d. a zinc dithiophosphate additive of
at least 0.1 weight percent of the composition and no more than 1.0
weight percent of the composition e. the composition having less
than 630 PPM phosphorus, less than 710 PPM zinc, less than 5,000
PPM sulfur, less than 8 TBN and less than 1.0 weight percent
ash.
2. The composition of claim 1 further comprising a molybdenum
additive wherein the molybdenum additive is less than 2 weight
percent of the composition.
3. The composition of claim 1 further comprising a boron additive
wherein the boron additive is less than 8 weight percent of the
composition.
4. The composition of claim 1 further comprising a sulfur
additive.
5. The composition of claim 1 wherein the composition has a
viscosity less than 20 cSt at 400.degree. C., fully saturated
structures with an iodine value less than 1 and a volatility less
than 15 weight percent loss in Noack.
6. The composition of claim 1 wherein the alkylated aromatic
concentration is at least 0.5 weight percent and no more than 8
weight percent of the composition.
7. The composition of claim 1 further comprising additives to
provide favorable lubricant performance wherein the additives are
chosen form the group comprising zinc dithiophosphates, borated or
non-borated dispersants, phenolic and aminic ashless anti-oxidants,
metal detergents, molybdenum or organic friction modifiers,
defoamants, seal swell additives, pour point depressants and others
including contemporary dispersant-detergent-inhibitor (DDI)
additive packages, and any combination thereof.
8. The composition of claim 1 wherein the base stock is chosen from
the group consisting of group II base stocks, group III base
stocks, group IV base stocks, and group V base stocks,
gas-to-liquids base stocks, and any combination thereof.
9. The composition of claim 1 wherein the dispersant systems
comprises additives chosen from the group consisting of borated and
non-borated succinimides, succinic acid-esters and amides,
alkylphenol-polyamine coupled Mannich adducts, and any combination
thereof.
10. The composition of claim 1 wherein the alkylated aromatic
additive is a mano-alkylate comprising a carbon and oxygen atomic
ratio of at least 10:1 and less than 400:1.
11. The composition of claim 1 wherein the alkylated aromatic
additive is an alkylated diphenyl sulfide.
12. The composition of claim 1 further comprising an ashless
antioxidant additive.
13. The composition of claim 1 further comprising a sulfur free
metal detergent.
14. The composition of claim 11 further comprising an aliphatic
sulfur additive.
15. A lubricant additive system for a lubricant composition,
comprising: a. an alkylated aromatic additive of less than 20
weight percent of the lubricant composition; b. a sulfur-free
detergent-dispersant system of less than 15 percent weight percent
of the lubricant composition; c. a zinc dithiophosphate additive of
at least 0.1 weight percent of the composition and no more than 1.0
weight percent of the lubricant composition; d. an alkylated
diphenyl sulfide additive
16. The lubricant additive of claim 15 wherein the total lubricant
additive treat is in the range of at least 0.01 weight percent and
less than 25 weight percent of the lubricant composition.
17. The lubricant additive of claim 15 further a molybdenum
additive.
18. The lubricant additive of claim 15 wherein the molybdenum
additive is an organic molybdenum additive.
19. The lubricant additive of claim 17 further comprising a non
volatile sulfur additive.
20. A method comprising a. obtaining a composition comprising a
lubricating oil basestock, an alkylated aromatic additive of at
least 0.01 and less than 20 weight percent of the composition, a
dispersant-detergent-inhibitor system of less than 15 percent
weight percent of the composition, zinc dithiophosphate additive of
at least 0.1 weight percent of the composition and no more than 1.0
weight percent of the composition, wherein the composition has less
than 630 PPM phosphorus, less than 710 PPM zinc, less than 5,000
PPM sulfur, less than 8 TBN, less than 1.0 weight percent ash; b.
lubricating an engine with the composition to achieve favorable
anti-wear properties, oxidation resistance and cleanliness.
21. A method for reducing sulfur in exhaust gasses in an internal
combustion engine, comprising: a. obtaining a composition
comprising a lubricating oil base stock, an alkylated aromatic
additive of at least 0.01 and less than 20 weight percent of the
composition, a dispersant-detergent-inhibitor system of less than
15 percent weight percent of the composition, zinc dithiophosphate
additive of at least 0.1 weight percent of the composition and no
more than 1.0 weight percent of the composition, wherein the
composition has less than 630 PPM phosphorus, less than 710 PPM
zinc, less than 5,000 PPM sulfur, less than 8 TBN, less than 1.0
weight percent ash; b. lubricating the internal combustion engine
with the composition.
Description
[0001] This application claims benefit of U.S. Ser. No. 60/758,840
filed Jan. 13, 2006.
BACKGROUND OF THE INVENTION
[0002] 1. Field of the Invention
[0003] This invention relates to lubricating oil compositions
suitable for use in internal combustion engines. More particularly,
this invention relates to a low ash, sulfur, and phosphorous
lubricating oil composition.
[0004] 2. Background
[0005] Many means have been employed to reduce overall wear and
friction as well as to control oxidation/cleanliness in modern
engines, particularly automobile engines. The primary reasons
include prolonging engine life by reducing engine wear and
increasing the resistance to oxidation by reducing the engine's
sludge/deposit through degradation. Many of the solutions to
reducing wear have been strictly mechanical including building
engines with wear resistant parts, modifying the contact geometry
and adding special coating materials. Other solutions to improve
cleanliness involve the use of metal containing detergents.
Recently, considerable work has also been done with lubricating
oils to enhance their anti-wear/anti-oxidation properties by
modifying them with ashless antioxidants and anti-wear
components.
[0006] Contemporary lubricants such as engine oils use mixtures of
additive components. Examples of additives components include,
anti-wear and extreme pressure components, fuel economy improving
components, friction reducers, dispersants, detergents, inhibitors
and viscosity index improving additive. These additives provide
energy conservation, engine cleanliness and durability and high
performance levels under a wide range of performance conditions
including temperature, pressure and lubricant service life.
[0007] Throughout the world, legislation aimed at reducing
automotive emissions is pushing down the level of sulfur in fuels.
Recently, lubricants are coming under scrutiny as a source of air
pollution and emission catalyst deactivation. Phosphorus is known
to be poisonous to automotive three-way HC conversion catalysts.
Sulfur is known to be poisonous to deNox catalysts and zinc/moly
phosphates are key contributors to cause plugging of the exhaust
particulate filters. The sulfur, ash and phosphorous components are
commonly referred to as "SAP" or "SAPS" in the art. Accordingly,
there is a need for a low sulfur, ash, and phosphorous component
additive for lubricating oils that provides favorable performance
properties.
[0008] Conventional engine oil technology relies heavily on zinc
dithiophosphate ("ZnDTP" or "ZDDP"). ZnDTP is a versatile,
anti-wear/anti-oxidant component that provides extremely low cam
and lifter wear and favorable oxidation protection under severe
conditions. ZnDTP is disadvantageous, especially at high treat
rates. The major problem with ZnDTP is the poisoning effects to
after-treatment devices that may aggravate emission problems. In
addition, ZnDTP has strong interactions with dispersants,
detergents, other anti-wear components and MoDTC causing
antagonistic effects on friction, sludge and deposit, if
inappropriate concentrations are utilized. Replacing ZnDTP
additives is not a simple endeavor since the wear protection demand
for today's engine is extremely high and extremely rigorous
chemical limits on ZnDTP.
[0009] Based on the above, there is a need for the development of a
low phosphorus, low sulfur and low ash lubricating oil and additive
with low levels of ZnDTP. Accordingly, this invention satisfies
that need.
SUMMARY OF THE INVENTION
[0010] In a first embodiment, a lubricating oil composition is
disclosed. This composition, comprises a lubricating oil basestock,
an alkylated aromatic additive of at least 0.01 and less than 20
weight percent of the composition, a dispersant-detergent-inhibitor
system of less than 15 percent weight percent of the composition, a
zinc dithiophosphate additive of at least 0.1 weight percent of the
composition and no more than 1.0 weight percent of the composition.
The composition having less than 630 PPM phosphorus, less than 710
PPM zinc, less than 5,000 PPM sulfur, less than 8 TBN, less than
1.0 weight percent ash.
[0011] In a second embodiment, an additive composition for
lubricating oils is disclosed. This composition comprises an
alkylated aromatic additive of less than 20 weight percent of the
composition, a dispersant-detergent-inhibitor system of less than
15 percent weight percent of the composition, a zinc
dithiophosphate additive of at least 0.1 weight percent of the
composition and no more than 1.0 weight percent of the
composition.
[0012] In a third embodiment, a method of obtain a favorable
lubricating properties is disclosed. This method, comprises
obtaining a composition comprising a lubricating oil basestock, an
alkylated aromatic additive of at least 0.01 and less than 20
weight percent of the composition, a dispersant-detergent-inhibitor
system of less than 15 percent weight percent of the composition,
zinc dithiophosphate additive of at least 0.1 weight percent of the
composition and no more than 1.0 weight percent of the composition,
wherein the composition has less than 630 PPM phosphorus, less than
710 PPM zinc, less than 5,000 PPM sulfur, less than 8 TBN, less
than 1.0 weight percent ash and a lubricating an engine with the
composition to achieve favorable anti-wear properties, oxidation
resistance and cleanliness.
BRIEF DESCRIPTION OF THE DRAWING
[0013] FIG. 1 illustrates the viscosity increase profiles for a
Group V base stock with different additive embodiments.
DETAILED DESCRIPTION OF THE INVENTION
[0014] This invention relates to engine lubricants formulated with
functional fluids and/or additives and compositions. One embodiment
is a low ash, sulfur, phosphorus engine lubricant compositions
comprising oils of lubricant viscosity containing a minor amount of
multi-functional anti-wear/anti-oxidation additive. The
anti-wear/anti-oxidation additive may be a functional fluid of
certain sulfur-containing alkylated aromatics or mixtures of sulfur
and non-sulfur alkylated aromatics.
[0015] In a second embodiment, the lubricating oils maintain low
frictional properties of film under various operating conditions.
This embodiment favorably maintains sufficiently high film
thickness at high operating temperatures to provide a minimum
lubricant film to protect against wear at a variety of
temperatures.
[0016] In a third embodiment, the lubricating oil maintains
cleanliness over the entire range of operating conditions while
reducing wear to an absolute minimum. In a fourth embodiment, the
lubricating oil provides favorable oxidation and corrosion control,
under the most severe operating conditions.
[0017] Traditionally, antiwear and extreme pressure additives have
been chosen from zinc dithiophosphates, phosphites, sulfurized
olefins/esters, sulfur-nitrogen additives and similar components.
Friction reducers have been chosen from molybdenum additives
including Moly dithiocarbamates ("MoDTC"), Molydithiophosphates
("MoDTP"), and other organic moly-containing compounds), amines,
amides and similar components. Metal detergents have been chosen
from calcium or magnesium phenates, sulfonates, salicylates,
carbonates and similar components. Antioxidants have been chosen
from hindered phenols, arylamines, dihydroquinolines, phosphites
and thiol/thiolester/disulfide/trisulfide compounds. These
additives are rich in sulfur, phosphorus and/or ash content as they
form strong chemical films to the metal surfaces.
[0018] Diphenyl sulfide, diphenyl oxide, biphenyl, diphenylmethane,
and many other related analogs are utilized as heat transfer fluids
since they are stable materials that can resist thermal stress
under severe conditions. However, the direct use of the
non-alkylated aromatics in lubricants are relatively limited to low
concentrations due to the limited compatibility with other
hydrocarbon base stocks.
[0019] Alkylated aromatics, especially sulfur containing alkylated
aromatics have been developed by applying alkylation technique to
functional or non-functional aromatics providing good
thermal-oxidative stability while maintaining good compatibility.
These alkylated aromatics have excellent compatibility with other
base oils and superb solvency and stability making them unique
synthetic oils including Group V or functional fluids. U.S. Pat.
Nos. 5,105,042, and 5,177,284 disclose the process conditions of
making alkylated naphthalenes. U.S. Pat. Nos. 5,372,734, 5,552,071,
5,371,248, and 5,286,396 disclose the preparation of alkylated
benzothiophene-derived lubricants, alkylated diphenyl ether
lubricants, alkylated benzofuran-derived lubricants and alkylated
phenoxathins for lubricants.
[0020] The prior art literature referenced above fails to disclose
the use of alkylated aromatics in a low SAP environment with high
quality base stocks. In addition, the prior art fails to disclose
the favorable anti-wear/anti-oxidation properties and unexpected,
superb cleanliness features which make the alkylated aromatics
functional fluids suitable for low ash and low phosphorus engine
oils. In different embodiments the preferred degree of alkylation
varies ranging from mono- to di- to multiple alkylates. However,
mono-alkylates are more desirable than others. The desired carbon
to sulfur and oxygen ratio is in a range from 10:1 to 400:1 on
atomic basis with a more preferred range of 20:1 to 200:1 and an
even more preferred range of 25:1 to 100:1.
[0021] In one embodiment, lubricating oils, especially synthetic
oils, when blended with low level of zinc dithiophosphates and/or
optionally molybdenum friction modifiers can provide substantial
reductions in wear and oxidation. These combinations provide
improvements in engine service life and durability with excellent
overall performance benefits. In addition, these combinations
typically minimize deleterious effects such as instability,
undesirable high viscosity, high friction, deposits and the like,
when added to lubricating oils. Combinations of alkylated aromatics
with low level of sulfur-free detergents such as, salicylates,
ashless phenols and arylamines, and boron containing additives, and
any combination thereof further provide synergies.
[0022] In another embodiment, novel highly stable, sulfur
containing, alkylated aromatics have been synthesized and evaluated
as functional fluids and/or additives for lubricants including low
ash, sulfur, phosphorus engine lubricants. The novel compositions
possess multi-functional
anti-wear/anti-oxidation/cleanliness/friction reducing-fuel economy
properties. In addition, these combinations can improve the wear
protection of most lubricants used in both automotive and
commercial diesel engine applications, while maintaining desirable
viscometrics. In this embodiment, the composition is favorable
suited for low ash passenger car engine oils. When used as Group V
base stocks including functional fluids or co-base stocks, the
typical alkylated aromatic concentration is in the range of 0.1 to
20 wt %, preferably 0.5 to 8 wt %. When used as lubricant
additives, the typical treat, sometimes referred to as treat rate,
is in the range of 0.01 to 4 wt % with a more preferred range of
0.02 to 2 wt % and an even more preferred range of 0.1 to 1 wt %.
The treat for an additive is based on the weight percent of the
active ingredient in the desired lubricant.
[0023] In a preferred embodiment, this invention is referred to as
a low ash, sulfur and phosphorus engine oil formulated with
extremely stable, sulfur functional fluids. However, this invention
is not limited to sulfur functional fluids. Other suitable
functional fluids include alkylated diphenyl sulfides, alkylated
diphenyl disulfides/polysulfides, alkylated naphthalenes, alkylated
benzenes, alkylated diphenyl ether, alkylated diphenylmethanes,
alkylated phenothiazines, alkylated phenoxazines, alkylated
benzothiazines, alkylated benzothiophenes, alkylated thiophenol,
alkylated thianthrene, similar and related components, and any
combinations thereof.
[0024] Preferably, the highly stable engine oil fluids has a very
low viscosity of less than 20 cSt at 400.degree. C., with fully
saturated structures with an Iodine value less than 1, low
volatility of less than 15 wt % loss in Noack and even more
preferably high resistance to oxidation/thermal breakdown. The most
preferred embodiment provides favorable viscometrics for engine
oils since fuel economy is heavily influenced by viscometrics. A
variety of alkylated aromatics are suitable for different
embodiments of this invention. For example, ADPS-1 is an
experimental synthetic fluid made by the alkylation of diphenyl
sulfide with long chain alkenes over the USY catalyst.
[0025] In a preferred embodiment, the lubricant compositions,
besides being built around the unique sulfur containing alkylated
aromatics, also contain low levels of zinc, phosphorus and sulfur
components. Persons skilled in the art will recognize the ability
to include additives that favorably enhances lubricant performance
including anti-friction, anti-oxidation and anti-wear performance
while successfully meeting the stringent wear, oxidation and
cleanliness performance requirements in modern engines. Examples of
suitable additives include but are not limited to contemporary zinc
dithiophosphates, borated or non-borated dispersants, phenolic and
aminic ashless anti-oxidants, high and low levels of metal
detergents, molybdenum or organic friction modifiers, defoamants,
seal swell additives, pour point depressants including contemporary
DDI additive packages, and any combination thereof.
[0026] In some embodiments, we have discovered that these new
synergistic combination has favorably improved lubricant
performance parameters while maintaining excellent compatibility to
exhaust after-treatment devices. The core of the preferred
embodiment comprises stable sulfur containing functional fluid and
a significantly reduced amount of ZnDTP and metal detergents, and
enhanced amount of ashless anti-oxidants and friction modifiers.
The resulting formulation provides an engine oil lubricant with
less than 630 PPM phosphorus, less than 710 PPM zinc, less than
5,000 PPM sulfur, less than 8 TBN, less than 1.0 wt % ash and high
nitrogen/zinc or nitrogen/phosphorus ratios. In one embodiment, the
general formulation of the low SAP engine oil containing the
alkylated aromatics is summarized in Table 1. TABLE-US-00001 TABLE
1 Elements in Formulated Oils (ppm) + Other Component Type Wt %
Restrictions Sulfur aromatic 0.01-20.0% .sup. <4500 ppm sulfur,
functional fluid/ volatility <10 wt % additive Zinc
dithiophosphate 0.1-1.0%.sup. 100-630 ppm phosphorus, additive
105-710 ppm zinc Dispersant-detergent- <15.0% <1800 ppm
nitrogen, inhibitor system <1.0 wt ash, TBN <8, N/P >1
(wt/wt) N/Zn >1 (wt/wt) Molybdenum additive 0-2.0% <210 ppm
molybdenum Boron additive 0-8.0% <400 ppm boron
[0027] These components can be used with a variety of base stocks,
including group I, II, III, IV, and V, and GTL as well as a variety
of mixtures thereof. However, due to other performance requirements
including volatility, stability, viscometrics, and cleanliness
feature, premium engine oils prefer to use group II and higher
("Group II+") base oils to ensure that they can achieve desirable
overall performance levels as well as maximizing the full potential
of the unique synergies among additives. Additional significant
synergies were identified among alkylated aromatics and Group II+
high performance base stocks is including Group II, III, IV, V, VI
or GTL base stocks.
[0028] Base stocks having a high paraffinic/naphthenic and
saturation nature (>90 wt %) can often be used advantageously in
certain embodiments. Such base stocks include Group II and/or Group
III hydroprocessed or hydrocracked base stocks, or their synthetic
counterparts such as polyalphaolefin oils, GTL or similar base oils
or mixtures of similar base oils.
[0029] In a preferred embodiment, at least about 20% of the total
composition should consist of such Group II or Group III base
stocks or GTL, with at least about 30% being preferable, and more
than about 80% on being most preferable. Gas to liquid base stocks
can also be preferentially used with the components of this
invention as a portion or all of the base stocks used to formulate
the finished lubricant. We have discovered, favorable improvement
when the components of this invention are added to lubricating
systems comprising primarily Group II, Group III and/or GTL base
stocks compared to lesser quantities of alternate fluids.
[0030] Suitable dispersants include borated and non-borated
succinimides, succinic acid-esters and amides,
alkylphenol-polyamine coupled Mannich adducts, other related
components and any combination thereof. In some embodiment, it can
often be advantageous to use mixtures of such above described
dispersants and other related dispersants. Examples include
additives that are borated, those that are primarily of higher
molecular weight, those that consist of primarily mono-succinimide,
bis-succinimide, or mixtures of above, those made with different
amines, those that are end-capped, dispersants wherein the
back-bone is derived from polymerization of branched olefins such
as polyisobutylene or from polymers such as other polyolefins other
than polyisobutylene, such as ethylene, propylene, butene, similar
dispersants and any combination thereof.
[0031] Suitable detergents include but are not limited to calcium
phenates, calcium sulfonates, calcium salicylates, magnesium
phenates, magnesium sulfonates, magnesium salicylates, metal
carbonates, related components including borated detergents, and
any combination thereof. The detergents can be neutral, mildly
overbased, or highly overbased.
[0032] The antioxidants include hindered phenols, arylamines, low
sulfur peroxide decomposers and other related components.
Inhibitors and antirust additives may be used as needed. Seal swell
control components and defoamants may be used with the mixtures of
this invention. Various friction modifiers may also be utilized.
Examples include but are not limited to amines, alcohols, esters,
diols, triols, polyols, fatty amides, various molybdenum
phosphorodithioates (MoDTP), molybdenum dithiocarbamates (MoDTC),
sulfur/phosphorus free organic molybdenum components, molybdenum
trinuclear components, and any combination thereof.
[0033] ZnDTP is widely utilized for providing anti-wear protection
to modern engine oils with few other components sharing similar
functions. As the levels of ZnDTP are reduced, the wear protection
must rely on a new anti-wear system. Preferably, that new anti-wear
system will be low in ash, sulfur and substantially free of
phosphorus components to provide favorable performance with the new
exhaust systems. Typically, the sulfur-containing alkylated
aromatics possess moderate level of highly stable, less volatile
sulfur, that is different from the volatile sulfur liberated from
zinc dithiophosphates. Therefore, these sulfur-containing alkylated
aromatics are harmless to exhaust after-treatment devices but
effective in protecting engine parts against wear mechanism.
[0034] In one embodiment, the principle advantage of this new
invention is the synergistic combination of multi-functional,
alkylated sulfur aromatics and small amount of zinc dithiophosphate
additives that favorably provides oxidation, corrosion, seal
stability and frictional properties. Even more important is the
ability to provide anti-wear protection with lower levels of
sulfur, phosphorus and zinc in the engine oil formulations are
significantly less than that typically used in today's engine oils.
Another principle advantage of this invention is the unique
combination of alkylated sulfur aromatics with boron-containing
additives for superb cleanliness features, such as the effective
control of undercrown deposit formation. Another principle
advantage in one embodiment is the synergistic combination of
alkylated sulfur aromatics and low level of sulfur-free metal
detergents including calcium and magnesium salicylates and
carbonates. An additional synergistic combination is an alkylated
sulfur aromatics with ashless anti-oxidants to improve oxidation
protection and extended drain intervals. Another potential
advantage is the unique combination embodiment of alkylated sulfur
aromatics with friction reducers to improve fuel economy.
EXAMPLES
[0035] Table 2 below discloses bench and tribology testing data for
alkylated diphenyl sulfide (experimental sample "ADPS-1") in
Passenger Vehicle Engine Oils. TABLE-US-00002 TABLE 2 Lubricant
Example 1 2 3 ADPS-1 = 93-59386 4% ADPS-1 01-60665 = 0% P Eo 1.0%
ZnDTP 0.5% ZnDTP 0.5% ZnDTP 99% 01-60665 99.5% 01-60665 95.5%
01-60665 Phosphorus, % 0.10 0.05 0.05 Sample Number 02-713 02-714
02-3361 1 Solubility C & B C & B C & B Appearance 4
Ball Wear WSD (mm) 0.44 0.48 0.42 40 Kg/1200 rpm/60 min./200 K
Factor 1.11 1.62 0.78 F. 4 Ball EP (D2783) LNS (Kg) 80 80 100 30
C./10 sec./1760 rpm Weld Ld (Kg) 200 200 200 LWI 35.1 34.5 41.7 Cu
Corrosion (D130-9) 24 hrs/250 F. 1A 1A 1A PDSC (Ramp 10 C./min)
Onset T (C.) 232 229.7 235.1 288.degree. C., 16 hrs 3.8 3.5 3.3
Tube Rating (1 = Clean) HFRR Scar X/Y 0.317/0.7 0.3/0.767 0.26/0.70
0.7 Kg/60 Hz/0.5 mm/ (mm) 60 min./75 C. Calc. Sc. Area 0.174 0.181
0.147 D2896 TBN 4.27 4.23 -- D874 (wt %) Sulfated Ash 0.53 0.38
0.35 D6443 (wt %) Phosphorus 0.1003 0.0507 0.0497 D6443 (wt %) Zinc
0.1118 0.0577 0.0572 D6443 (wt %) Calcium 0.0329 0.0332 0.0317
D6443 (wt %) Magnesium 0.0595 0.0496 0.0482 D6443 (wt %) Copper
<0.002 <0.002 <0.002 D6443 (wt %) Chlorine 0.0047 0.0049
0.0048 D6443 (wt %) Sulfur 0.2799 0.1783 0.4761
[0036] The base formulation (01-60665) is a phosphorus-free,
partially formulated engine oil with Group III base stocks, ashless
antioxidants, ashless dispersants, metal detergents, defoamants,
viscosity modifiers and other performing components.
[0037] As illustrated in the above Table 2, very good anti-wear,
anti-oxidation and corrosion control can be achieved with
sulfur-derived alkylated aromatics in the low P passenger vehicle
lubricants ("PVL"). As shown in the High Frequency Reciprocating
Rig ("HFRR") and Four-Ball EP wear test, the functional fluids
formulated low SAPS engine oils can help to improve anti-wear
properties evidenced by the low wear scar areas and wear
coefficients ("K Factor") measured.
[0038] In addition, there are synergistic benefits of low SAP
additives with Group II and higher base stocks. The synergistic
benefits include favorable cleanliness, wear properties, catalyst
compatibility and oxidation.
[0039] Comparing lubricant example 1 by adding 1000 ppm phosphorus
and lubricant example 2 by adding 500 ppm phosphorus, noticeable
anti-wear performance differences can be seen, which are believed
to be directly affected by ZnDTP concentrations. Typically, the
more ZnDTP, the better anti-wear protection. However, when 4%
alkylated diphenyl sulfide was added to make lubricant example 3,
which has the same level of 500 ppm phosphorus as lubricant example
2, a significant 19% reduction of wear scar areas and an observed
52% reduction in wear coefficients was measured.
[0040] The Table 2 results for lubricant example 3 are even better
when compared to lubricant example 1. In the presence of more
ZnDTP, for example 1000 ppm P in lubricant example 1 versus 500 ppm
P in lubricant example 2, a reduction of calculated scar area from
0.18 mm.sup.2 to 0.174 mm.sup.2 is expected. However, a significant
reduction to 0.147 mm.sup.2 range for lubricant example 3 is an
unexpected result.
[0041] In the Four-Ball EP test, lubricant example 3 also
demonstrated superb load carrying property as evidenced by the
higher last non-seizure load of 100 kg and a greater Load Wear
Index of 41.7 when compared to lubricant examples 1 and 2. The
improvement in Load Wear Index from lubricant examples 2 to
lubricant examples 3 is almost 21%. The high temperature stability
of lubricant example 3 is also shown by the Pressured differential
Scanning Calorimetry ("PDSC") data on ramping method. Comparing
lubricant examples 2 to 3, the onset temperature is raised from
229.7.degree. C. to 235.1.degree. C. respectively providing 54%
better oxidation control, assuming the oxidation rates doubled with
every 10.degree. C. increase in temperature. Therefore, lubricant
example 3 could provide 54% better oxidation resistance than
lubricant 2 if we quantify the control by viscosity or acid value
increases or any other measurements.
[0042] The hot tube test is also used to assess cleanliness
features of engine oils under high temperature oxidation
conditions. As exhibited in Table 2, lubricant example 3 has
slightly better cleanliness result than both lubricant examples 1
and 2 as the lower the rating, the better the cleanliness. This
data illustrates that more ZnDTP reduces lubricant cleanliness as
lubricant example 1 has the worst result as ZnDTP is known to
decompose to various species at elevated temperatures. The copper
corrosion results indicated that adding ADPS to the engine oil
formulations causes no adverse impact to their copper corrosivity.
Adding ADPS will certainly increase the sulfur content of the
engine oil. However, the final sulfur level of 0.476 wt % for
lubricant example 3 is still under the current ILSAC GF-4 standard
of 0.5 wt %. In conclusion, exceptionally good oxidative stability
and low wear in low phosphorous engine oils can be achieved by
using alkylated sulfur aromatics such as, ADPS thus providing
favorable performance properties suitable for modern engine
oils.
[0043] The outstanding anti-oxidation/anti-wear performance is
further verified by another set of Four-ball EP and hot tube tests.
Table 3 is a Table similar to Table 2 comparing lubricant examples
1 and 2 from Table 2 with additional lubricant example tests. As
shown in the Table 3 data, when the low phosphorus engine oil was
formulated with extremely low level of ZnDTP such as, 0.025 wt %
phosphorous, the last non-seizure load dropped to 63 kg and the
load wear index also dropped to 28.2 comparing table 4 lubricant
example 4 versus lubricant examples 2 and 1. This is clearly not
desirable as poor EP performance indicates weak load carrying
property. Adding a conventional sulfur EP additive, Rhein-Chemie's
RC-2411.TM., could not improve the load carrying property
significantly as shown in lubricant example 5. However, as shown in
example 6, adding 2 wt % of ADPS to the base engine oil formulation
provides significant improvement. TABLE-US-00003 TABLE 3 Lubricant
Example 1 2 4 5 6 Funct'lized fluids 2% ADPS-1 or cobase oil
01-60665 = 1% ZnDTP 0.5% ZnDTP 0.25% ZnDTP 0.25% ZnDTP 0.25% ZnDTP
0% P EO 99% 01-60665 99.5% 01-60665 99.75% 01-60665 99.5% 01-60665
97.5% 01-60665 .25% RC2411 .25% RC2411 (0.10% P) (0.05% P) 0.025% P
0.025% P 0.025% P Sample Number 02-713 02-714 02-31205 02-35335
02-35333 Solubility/ C & B C & B C & B C & B C
& B Appearance 4 Ball EP LNS (Kg) 80 80 63 63 80 (D2783) Weld
Ld (Kg) 200 200 200 200 250 30 C./10 sec./17 LWI 35.1 34.47 28.21
28.41 36.16 60 rpm Cu Corrosion 3 hrs/ 1A 1B 1A 1B 1B (D130-8) 210
F./H2O Cu Corrosion 24 hrs/250 F. 1A 1A 2A 2B 2A (D130-9)
288.degree. C., 16 hrs 3.8 3.5 2.8 2.8 Tube Rating (1 = Clean)
D2896 TBN 4.27 4.23 5.45 4.11 5.59 D874 (wt %) Sulfated Ash 0.53
0.38 0.33 0.33 0.32 D6443 (wt %) Phosphorus 0.1003 0.0507 0.0244
0.0245 0.0246 D6443 (wt %) Zinc 0.1118 0.0577 0.0287 0.0278 0.028
D6443 (wt %) Calcium 0.0329 0.0332 0.0331 0.0331 0.0325 D6443 (wt
%) Magnesium 0.0595 0.0496 0.0505 0.0501 0.0514 D6443 (wt %) Copper
<0.002 <0.002 <0.002 <0.002 <0.002 D6443 (wt %)
Chlorine 0.0047 0.0049 0.0048 0.005 0.0049 D6443 (wt %) Sulfur
0.2799 0.1783 0.124 0.1463 0.2988
[0044] RC-2411.TM. is an aliphatic sulfur additive, which has even
higher sulfur content than the ADPS used in lubricant example 6 of
table 3. Some sulfur-containing additives, including aliphatic
sulfur species, could provide equivalent favorable antiwear/extreme
pressure performance as alkylated sulfur aromatics providing that
they are thermally stable and non-corrosive. However, many
sulfur-containing aliphatic sulfur additives, used by themselves
alone, are not sufficient to provide anti-wear protection while
maintaining satisfactory anti-corrosion properties as demonstrated
in example 4 and 5 of table 3. Lubricant example 6 (with levels of
0.025 wt % phosphorus) of table 3 illustrates the last non-seizure
load and the load-wear index improved to be equivalent to or better
than the lubricant example 1 with levels of 0.1 wt % phosphorus
engine oil. In addition, the weld load increased to 250 kg when
comparing lubricant example 6 to lubricant example 1. Lubricant
example 6 shows a synergistic benefits of using an ADPS aliphatic
sulfur compound with group II and higher base stock.
[0045] These results are exceptional favorable in the presence of
additive treat level of ADPS. As stated before, the hot-tube test
is used to measure the relative cleanliness of engine oils with the
higher the rating on the scale form 1 to 9, the dirtier the
lubricant. Lubricant example 6, ADPS formulated oil, demonstrated
better cleanliness than oils with higher levels of ZnDTP including
lubricant examples 1 and 2. As shown in table 3 for lubricant
example 5, the total sulfur of the ADPS containing formulation is
below the ILSAC GF-4 requirements.
[0046] FIG. 1 illustrates the viscosity increase profiles for a
Group V base stock with different additive embodiments. Reference
numerals 11 and 12 represent viscosity increase profiles for two
runs for 7 wt % alkylated naphthanates additives. Reference numeral
13 represents viscosity increase profiles for 7 wt % of TMP ester
and 14 represents a viscosity increase profile for 7% dibasic acid
ester (adipate ester). Finally, the reference numerals 15 and 16
represent viscosity increase profiles for 7 wt % and 1 wt % ADPS
additive respectively.
[0047] FIG. 1 demonstrates that alkylated sulfur aromatics 15 and
16 can provide favorable performance advantages in oxidation
control versus other group V synthetic fluids in the presence of
equal amount of ashless anti-oxidants. This performance benefit was
shown using the ExxonMobil Research Catalytic Oxidation Test
("ERCOT"). In the ERCOT test, 50 ppm of soluble iron is added to
100 g of test fluid. The fluid is heated at 165.degree. C. while
air is bubbled through the sample at a rate of IL/hour. The
kinematic viscosity at 40.degree. C. of the catalyzed oil is
monitored as a function of time. When the antioxidants in the fluid
are consumed, a significant increase in viscosity is observed. The
base engine oil formulation has about 450 ppm phosphorus from
reduced ZnDTP, and a total of 1.0 wt % hindered phenol and
alkylated arylamine ashless anti-oxidants. In the presence of 7 wt
% experimental ADPS-1, the oil induction time has been increased by
70-80 hours in the ERCOT test. Even present in just 1 wt % ADPS,
the oil induction time can still be 40-50 hours longer than
synthetic esters or alkylated naphthalenes. Therefore, FIG. 1
illustrates the strong synergy of ADPS with an ashless
anti-oxidant.
[0048] Another important performance feature of the current
invention is after-treatment compatibility. To measure
after-treatment compatibility, a series of engine oil samples were
prepared where each sample contained a single sulfur containing
species as shown in Table 4. Thus, the fully formulated engine oils
studied contained only the single source of sulfur listed in Table
4. Secondary ZDDP, Primary ZDDP, Thiadiazole, Sulfur-phenol,
sulfurized olefin, and ADPS were studied. These fully formulated
engine oils contain typical non-sulfur containing performance
additives such as hindered phenols, alkylated arylamines, ashless
dispersants, metal and ashless detergents, friction modifiers,
defoamants, corrosion inhibitors, copper passivators, pour point
depressants and seal swell agents. The single sulfur containing
species in Table 4 were the last components added. Samples were
volatilized at 250.degree. C. for 15 minutes using D 5800 and a
comparison of the percent sulfur lost between the new oil and the
oil remaining at the end of the volatilization test was made. In a
direct comparison of Table 4, primary and secondary zinc
dithiophosphates volatized at 12.0% and 37.0% respectively.
Commercial sulfur-containing antioxidants volatized at 6.1%,
thiadiazole at 21.8%, molybdenum dithiocarbamate at 12.7%, and
sulfurized olefin additive at 10.5%. ADPS exhibited extraordinarily
low volatility at 2.0%. This data provides strong evidence for the
favorable low emission performance benefit of using ADPS in engine
oils. In this embodiment, the invention provides favorable benefit
in sustaining the useful life of the after-treatment system by
identifying a method to reduce volatile sulfur species to the
exhaust system. TABLE-US-00004 TABLE 4 15 Minute D5800 Sulfur
Volatilization Study Sulfur Volatilized, % 2.degree. ZDDP 37.0
Thiadiazole 21.8 Moly Dithiocarbamate 12.7 1.degree. ZDDP 12.0
Sulfurized Olefin 10.5 Sulfur Phenol* 6.1 ADPS 2.0
[0049] All alkylated aromatics dissolved easily in engine oils and
remained clear and bright on the shelf at ambient temperatures over
period of six months or longer. Apparently, the stability of
alkylated sulfur aromatics-containing oils is satisfactory and they
cause no adverse effects to compatibility in the presence of other
commonly used additives in engine oil compositions.
[0050] Besides unique, synergistic additive effects, it is
evidenced that other highly refined, low sulfur Group II/III based
oils including both hydro-processed oils and HDP as well as other
Group IV/V synthetic base oils can be used to achieve favorable
lubricant performance.
[0051] In summary, in one embodiment, we have discovered a new
class of low sulfur, low ash and low phosphorous ("SAP") engine
oils with favorable oxidation and wear protection based on
alkylated sulfur-containing aromatics. This offers an effective way
to reduce the amount of ZnDTP for contemporary engine oils while
maintaining excellent wear, friction and oxidation performance as
well as meeting stringent emission requirements. This embodiment
further provides favorable synergisms to similar formulations
comprising alkylated sulfur aromatics, base oils of less than 300
ppm sulfur, low levels of ZnDTP wherein the ZnDTP contributes less
than 630 ppm phosphorus and/or less than 710 ppm zinc, sulfur
containing additives and molybdenum containing additives.
* * * * *