U.S. patent application number 14/706293 was filed with the patent office on 2015-11-12 for method for preventing or reducing low speed pre-ignition.
This patent application is currently assigned to ExxonMobil Research and Engineering Company. The applicant listed for this patent is Raymond G. Burns, III, Smruti A. Dance, Douglas E. Deckman, Charles E. Goldmann, Kevin J. Kelly, Mrugesh N. Patel. Invention is credited to Raymond G. Burns, III, Smruti A. Dance, Douglas E. Deckman, Charles E. Goldmann, Kevin J. Kelly, Mrugesh N. Patel.
Application Number | 20150322369 14/706293 |
Document ID | / |
Family ID | 54367274 |
Filed Date | 2015-11-12 |
United States Patent
Application |
20150322369 |
Kind Code |
A1 |
Patel; Mrugesh N. ; et
al. |
November 12, 2015 |
METHOD FOR PREVENTING OR REDUCING LOW SPEED PRE-IGNITION
Abstract
A method for preventing or reducing low speed pre-ignition in an
engine lubricated with a lubricating oil by using as the
lubricating oil a formulated oil. The formulated oil has a
composition including a lubricating oil base stock as a major
component, and at least one zinc-containing compound or at least
one antiwear agent, as a minor component. The at least one antiwear
agent includes at least one zinc dialkyl dithiophosphate compound
derived from a secondary alcohol. A lubricating engine oil having a
composition including a lubricating oil base stock as a major
component, and at least one zinc-containing compound or at least
one antiwear agent, as a minor component. The lubricating oils of
this disclosure are particularly advantageous as passenger vehicle
engine oil products.
Inventors: |
Patel; Mrugesh N.;
(Philadelphia, PA) ; Deckman; Douglas E.; (Mullica
Hill, NJ) ; Dance; Smruti A.; (Robbinsville, NJ)
; Kelly; Kevin J.; (Mullica Hill, NJ) ; Burns,
III; Raymond G.; (Aston, PA) ; Goldmann; Charles
E.; (Williamstown, NJ) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Patel; Mrugesh N.
Deckman; Douglas E.
Dance; Smruti A.
Kelly; Kevin J.
Burns, III; Raymond G.
Goldmann; Charles E. |
Philadelphia
Mullica Hill
Robbinsville
Mullica Hill
Aston
Williamstown |
PA
NJ
NJ
NJ
PA
NJ |
US
US
US
US
US
US |
|
|
Assignee: |
ExxonMobil Research and Engineering
Company
Annandale
NJ
|
Family ID: |
54367274 |
Appl. No.: |
14/706293 |
Filed: |
May 7, 2015 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61990772 |
May 9, 2014 |
|
|
|
Current U.S.
Class: |
508/162 ;
508/192; 508/194; 508/198; 508/370; 508/387; 508/502; 508/539;
508/566 |
Current CPC
Class: |
C10M 125/24 20130101;
C10N 2010/04 20130101; C10M 127/04 20130101; C10N 2040/25 20130101;
C10M 2207/122 20130101; C10M 2207/028 20130101; C10M 2207/123
20130101; C10M 133/16 20130101; C10M 137/02 20130101; C10M 129/54
20130101; C10M 2219/046 20130101; C10M 2223/045 20130101; C10M
163/00 20130101; C10N 2030/52 20200501; C10M 2207/146 20130101;
C10M 2207/16 20130101; C10N 2040/255 20200501; C10M 135/10
20130101; C10M 2201/085 20130101; C10N 2030/45 20200501; C10M
2207/262 20130101; C10M 129/68 20130101; C10M 2217/043 20130101;
C10N 2060/14 20130101; C10M 2215/28 20130101 |
International
Class: |
C10M 137/02 20060101
C10M137/02; C10M 129/68 20060101 C10M129/68; C10M 133/16 20060101
C10M133/16; C10M 127/04 20060101 C10M127/04; C10M 129/54 20060101
C10M129/54; C10M 135/10 20060101 C10M135/10; C10M 125/24 20060101
C10M125/24 |
Claims
1. A method for preventing or reducing low speed pre-ignition in an
engine lubricated with a lubricating oil by using as the
lubricating oil a formulated oil, said formulated oil having a
composition comprising a lubricating oil base stock as a major
component; and at least one zinc-containing compound or at least
one antiwear agent, as a minor component; wherein said at least one
antiwear agent comprises at least one zinc dialkyl dithiophosphate
compound derived at least in part from a secondary alcohol; and
wherein the engine exhibits greater than 20% reduced low speed
pre-ignition, based on normalized low speed pre-ignition (LSPI)
counts per 25,000 engine cycles, engine operation at 2000
revolutions per minute (RPM) and brake mean effective pressure
(BMEP) at 18 bar, as compared to low speed pre-ignition performance
achieved in an engine using a lubricating oilthat does not comprise
at least one zinc-containing compound or antiwear agent.
2. The method of claim 1 wherein the minor component further
comprises at least one boron-containing compound, wherein said
boron-containing compound comprises at least one borated
dispersant, or a mixture of a boron-containing compound and a
non-borated dispersant.
3. The method of claim 1 wherein the minor component further
comprises at least one boron-containing compound and at least one
detergent, wherein said boron-containing compound comprises at
least one borated dispersant, or a mixture of a boron-containing
compound and a non-borated dispersant, and wherein said detergent
comprises at least one alkaline earth metal salt of an organic
acid, and said at least one alkaline earth metal salt of an organic
acid comprises at least one magnesium salt of an organic acid.
4. The method of claim 1 wherein the lubricating oil base stock
comprises a Group I, Group II, Group III, Group IV, or Group V base
oil.
5. The method of claim 1 wherein the Group V base oil comprises an
ester base oil in a concentration of 2% to 20% and having a
kinematic viscosity at 100.degree. C. of 2 cSt to 8 cSt, and the
Group III base oil comprises a GTL base oil.
6. The method of claim 1 wherein the zinc-containing compound is
selected from the group consisting of zinc sulfonate, zinc acetate,
zinc napthenate, zinc alkenyl succinate, zinc acid phosphate salt,
zinc phenate, and zinc salicylate.
7. The method of claim 1 wherein the zinc dialkyl dithiophosphate
compound is represented by the formula
Zn[SP(S)(OR.sup.1)(OR.sup.2)].sub.2 wherein R.sup.1 and R.sup.2 are
independently primary or secondary C.sub.1 to C.sub.8 alkyl groups,
provided at least one of R.sup.1 and R.sup.2 is a secondary C.sub.1
to C.sub.8 alkyl group.
8. The method of claim 7 wherein the primary or secondary C.sub.1
to C.sub.8 alkyl groups of the zinc dialkyl dithiophosphate
compound are derived from an alcohol selected from the group
consisting of: 2-propanol (C3), 1-butanol (n-C4), 1-isobutanol
(1-i-C4), 2-butanol (2-C4), 1-pentanol (primary C-5),
3-methyl-1-butanol (primary C-5), 2-pentanol (C5), 3-pentanol (C5),
3-methyl-2-butanol (C5), 1-hexanol (primary C6),
4-methyl-1-pentanol (primary C6), 4-methyl-2-pentanol (C6), and
2-ethyl-1-hexanol (primary C8), and mixtures thereof.
9. The method of claim 7 wherein the zinc dialkyl dithiophosphate
compound is derived from (i) a C.sub.3 to C.sub.8 secondary
alcohol, or a mixture thereof; or (ii) a mixture of a C.sub.1 to
C.sub.8 primary alcohol and a C.sub.1 to C.sub.8 secondary
alcohol.
10. The method of claim 1 wherein (i) zinc content contributed by
the zinc-containing compound or antiwear agent in the lubricating
oil ranges from 500 ppm to 2000 ppm; (ii) phosphorus content
contributed by the zinc-containing compound or antiwear agent
compound in the lubricating oil ranges from 400 ppm to 2000 ppm;
(iii) zinc to phosphorus ratio in the lubricating oil ranges from
1.0 to 2.0; or (iv) the ratio of total metals provided by the
detergent to total metals provided by the zinc-containing compound
and antiwear agent is 0.8 to 4.8.
11. The method of claim 1 wherein the zinc-containing compound or
antiwear agent concentration ranges from 1.0 to 5.0 weight percent,
based on the total weight of the lubricating oil.
12. The method of claim 1 wherein the engine exhibits greater than
25% reduced low speed pre-ignition, based on normalized low speed
pre-ignition (LSPI) counts per 25,000 engine cycles, engine
operation at 2000 revolutions per minute (RPM) and brake mean
effective pressure (BMEP) at 18 bar, as compared to low speed
pre-ignition performance achieved in an engine using a lubricating
oil that does not comprise at least one zinc-containing compound or
antiwear agent.
13. The method of claim 2 wherein the boron-containing compound or
borated dispersant is selected from the group consisting of a
borated succinimide, a borated succinate ester, a borated succinate
ester amide, a borated Mannich base, and mixtures thereof; and the
non-borated dispersant comprises a succinic anhydride derived
succinimide or succinate ester with a coupling agent, wherein the
coupling agent comprises a boron-containing compound.
14. The method of claim 2 wherein boron is provided to the
lubricating oil by a mixture of an organic or inorganic
boron-containing compound and a borated succinimide, a borated
succinate ester, a borated succinate ester amide, a Mannich base
ester, or mixtures thereof; wherein the borated succinimide is a
mono succinimide, bis-succinimide, or a mixture thereof.
15. The method of claim 2 wherein the ratio of total zinc from the
zinc-containing compound and antiwear agent plus total alkaline
earth metal from the detergent divided by the total boron from the
boron-containing compound and borated dispersant, in the
lubricating oil, is 9.2 to 45.
16. The method of claim 2 wherein the boron-containing compound and
borated dispersant concentration ranges from 0.1 to 20 weight
percent, based on the total weight of the lubricating oil.
17. The method of claim 2 wherein the engine exhibits greater than
25% reduced low speed pre-ignition, based on normalized low speed
pre-ignition (LSPI) counts per 25,000 engine cycles, engine
operation at 2000 revolutions per minute (RPM) and brake mean
effective pressure (BMEP) at 18 bar, as compared to low speed
pre-ignition performance achieved in an engine using a lubricating
oil that does not comprise at least one zinc-containing compound or
antiwear agent and does not comprise at least one boron-containing
compound.
18. The method of claim 3 wherein the alkaline earth metal salt of
an organic acid is selected from the group consisting of an
alkaline earth metal sulfonate, an alkaline earth metal
carboxylate, an alkaline earth metal phenate, an alkaline earth
metal phosphate, and mixtures thereof.
19. The method of claim 3 wherein the detergent comprises (i) at
least one of magnesium sulfonate, magnesium phenate, and magnesium
salicylate, and mixtures thereof, and optionally at least one of
calcium sulfonate, calcium phenate, and calcium salicylate, and
mixtures thereof; (ii) at least one magnesium salt of an organic
acid which is selected from magnesium sulfonate, magnesium
carboxylate, magnesium phenate, magnesium phosphate, and mixtures
thereof; or (iii) magnesium sulfonate, a mixture of magnesium
sulfonate and magnesium salicylate, a mixture of magnesium
sulfonate and magnesium phenate, or a mixture of magnesium
sulfonate and magnesium carboxylate.
20. The method of claim 19 wherein, in a detergent comprising a
mixture of a magnesium salt of an organic acid and a calcium salt
of an organic acid, the detergent ratio of magnesium metal to
calcium metal ranges from 1:0 to 1:10.
21. The method of claim 3 wherein (i) magnesium and alkaline earth
metal contributed by the detergent is present in the lubricating
oil in an amount from 500 ppm to 5000 ppm; (ii) total base number
(TBN), as measured by ASTM D2896, contributed by the detergent
ranges from 2 mg KOH/g to 17 mg KOH/g; or (iii) sulfated ash
contributed by the detergent ranges from 0.4 to 1.7 wt %.
22. The method of claim 3 wherein the detergent concentration
ranges from 1.0 to 6.0 weight percent, based on the total weight of
the lubricating oil.
23. The method of claim 3 wherein the engine exhibits greater than
75% reduced low speed pre-ignition, based on normalized low speed
pre-ignition (LSPI) counts per 25,000 engine cycles, engine
operation at 2000 revolutions per minute (RPM) and brake mean
effective pressure (BMEP) at 18 bar, as compared to low speed
pre-ignition performance achieved in an engine using a lubricating
oil that does not comprise at least one zinc-containing compound or
antiwear agent and does not comprise at least one boron-containing
compound, and at least one detergent.
24. The method of claim 1 wherein the lubricating oil further
comprises one or more of a viscosity index improver, antioxidant,
pour point depressant, corrosion inhibitor, metal deactivator, seal
compatibility additive, anti-foam agent, inhibitor, anti-rust
additive, and friction modifier.
25. The method of claim 1 wherein the lubricating oil is a
passenger vehicle engine oil (PVEO).
26. A lubricating engine oil having a composition comprising a
lubricating oil base stock as a major component; and at least one
zinc-containing compound or at least one antiwear agent, as a minor
component; wherein said at least one antiwear agent comprises at
least one zinc dialkyl dithiophosphate compound derived at least in
part from a secondary alcohol; and wherein the engine exhibits
greater than 20% reduced low speed pre-ignition, based on
normalized low speed pre-ignition (LSPI) counts per 25,000 engine
cycles, engine operation at 2000 revolutions per minute (RPM) and
brake mean effective pressure (BMEP) at 18 bar, as compared to low
speed pre-ignition performance achieved in an engine using a
lubricating oil that does not comprise at least one zinc-containing
compound or antiwear agent.
27. The lubricating engine oil of claim 26 wherein the minor
component further comprises at least one boron-containing compound,
wherein said boron-containing compound comprises at least one
borated dispersant, or a mixture of a boron-containing compound and
a non-borated dispersant.
28. The lubricating engine oil of claim 26 wherein the minor
component further comprises at least one boron-containing compound
and at least one detergent, wherein said boron-containing compound
comprises at least one borated dispersant, or a mixture of a
boron-containing compound and a non-borated dispersant, and wherein
said detergent comprises at least one alkaline earth metal salt of
an organic acid, and said at least one alkaline earth metal salt of
an organic acid comprises at least one magnesium salt of an organic
acid.
29. An engine lubricated with the lubricating engine oil of claim
26.
30. A method for preventing or reducing low speed pre-ignition in
an engine lubricated with a lubricating oil by using as the
lubricating oil a formulated engine oil, said formulated engine oil
having a composition comprising a lubricating oil base stock at
from 70 to 85 wt. %; and at least one zinc-containing compound or
at least one antiwear agent, at a loading to contribute from 400
ppm to about 2000 ppm of phosphorous to the formulated engine oil;
wherein said at least one antiwear agent comprises at least one
zinc dialkyl dithiophosphate compound derived at least in part from
a secondary alcohol; wherein the engine exhibits greater than 50%
reduced low speed pre-ignition, based on normalized low speed
pre-ignition (LSPI) counts per 25,000 engine cycles, engine
operation at 2000 revolutions per minute (RPM) and brake mean
effective pressure (BMEP) at 18 bar, as compared to low speed
pre-ignition performance achieved in an engine using a lubricating
oil that does not comprise at least one zinc-containing compound or
at least one antiwear agent.
31. The method of claim 30 wherein the formulated engine oil
comprises SAE 0W-X or 5W-X wherein X is selected from the group
consisting of 8, 12, 16, 20, 30, and 40.
32. The method of claim 30 wherein the at least one lubricating oil
base stock has a kinematic viscosity ranging from 3.5 cSt to 6.0
cSt at 100 C.
33. The method of claim 30 wherein the formulated engine oil has a
TBN of 4 to 10 and exhibits substantial elimination of LSPI.
34. The method of claim 30 wherein the formulated engine oil has a
TBN of 10 to 20 and exhibits a LSPI reduction of at least 50%.
35. The method of claim 30 wherein the formulated engine oil
includes an ash level of from 0.2 to 1.0 wt. % and exhibits a
substantial elimination of LSPI.
36. The method of claim 30 wherein the formulated engine oil
includes an ash level of from 1.0 to 2.0 wt. % and exhibits a LSPI
reduction of at least 50%.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application No. 61/990,772 filed May 9, 2014, herein incorporated
by reference in its entirety.
RELATED APPLICATIONS
[0002] This application is related to two other co-pending
applications, filed on even date herewith, and identified by the
following Attorney Docket numbers and titles: 2014EM102-US2
entitled "Method for Preventing or Reducing Low Speed Pre-Ignition"
and 2014EM103-US2 entitled "Method for Preventing or Reducing Low
Speed Pre-Ignition"; all of which are incorporated herein in their
entirety by reference.
FIELD
[0003] This disclosure relates to a method for preventing or
reducing low speed pre-ignition (LSPI) in an engine lubricated with
a lubricating oil by using as the lubricating oil a formulated oil
that has at least one zinc-containing compound or at least one
antiwear agent, preferably at least one zinc dialkyl
dithiophosphate compound derived at least in part from a secondary
alcohol, present in a particular amount in the formulated oil. The
lubricating oils of this disclosure are useful as passenger vehicle
engine oil (PVEO) products.
BACKGROUND
[0004] Pre-ignition in a flame propagation (or "spark-ignition")
engine describes an event wherein the air/fuel mixture in the
cylinder ignites before the spark plug fires. Pre-ignition is
initiated by an ignition source other than the spark, such as hot
spots in the combustion chamber, a spark plug that runs too hot for
the application, or carbonaceous deposits in the combustion chamber
heated to incandescence by previous engine combustion events.
[0005] Many passenger car manufacturers have observed intermittent
pre-ignition in their production turbocharged gasoline engines,
particularly at low speeds and medium-to-high loads. At these
elevated loads, pre-ignition usually results in severe engine knock
that can damage the engine. The cause of the pre-ignition is not
fully understood, and may in fact be attributed to multiple
phenomena such as hot deposits within the combustion chamber,
elevated levels of lubricant vapor entering from the PCV system,
oil seepage past the turbocharger compressor seals or oil and/or
fuel droplet auto-ignition during the compression stroke.
[0006] Pre-ignition can sharply increase combustion chamber
temperatures and lead to rough engine operation or loss of
performance. Traditional methods of eliminating pre-ignition
include, for example, proper spark plug selection, proper fuel/air
mixture adjustment, and periodic cleaning of the combustion
chambers. Hardware solutions such as cooled exhaust gas
recirculation (EGR) are known, but these can be costly to implement
and present packaging problems.
[0007] Low speed pre-ignition (LSPI) is a type of abnormal
combustion affecting engines operating at high brake mean effective
pressure (BMEP) and low engine speed (RPM). Downsized, downspeeded,
turbocharged engines are most susceptible to operating under these
engine conditions and are thus more susceptible to LSPI. As the
automobile industry continues to move towards further downsizing,
downspeeding, and increased turbocharging to increase vehicle fuel
economy and reduce carbon dioxide emissions, the concern over LSPI
continues to grow.
[0008] The further development of downspeeded, turbocharged
gasoline engines is being impeded by LSPI. A solution to this
problem or even a mitigation of its occurrence would remove
barriers for original equipment manufacturer (OEM) technology and
efficiency improvement. A lubricant formulation solution would
enable product differentiation with regard to LSPI.
[0009] Although pre-ignition problems can be and are being resolved
by optimization of internal engine components and by the use of new
component technology such as electronic controls, modification of
the lubricating oil compositions used to lubricate such engines is
desirable. For example, it would be desirable develop new
lubricating oil formulations which are particularly useful in
internal combustion engines and, when used in internal combustion
engines, will prevent or minimize the pre-ignition problems. It is
desired that the lubricating oil composition be useful in
lubricating gasoline-fueled, spark-ignited engines.
[0010] Despite the advances in lubricant oil formulation
technology, there exists a need for an engine oil lubricant that
effectively prevents or reduces low speed pre-ignition especially
for downsized, downspeeded, turbocharged engines.
SUMMARY
[0011] This disclosure relates in part to new lubricating oil
formulations which are particularly useful in internal combustion
engines and, when used in internal combustion engines, will prevent
or minimize pre-ignition problems. The lubricating oil compositions
of this disclosure are useful in lubricating gasoline-fueled,
spark-ignited engines. The lubricant formulation chemistry of this
disclosure can be used to prevent or control the detrimental effect
of LSPI in engines which have already been designed or sold in the
marketplace as well as future engine technology. The lubricant
formulation chemistry of this disclosure removes barriers for OEM
technology and efficiency improvement, and enables further
development of downspeeded, turbocharged gasoline engines that is
currently being impeded by LSPI. The lubricant formulation solution
afforded by this disclosure for preventing or reducing LSPI enables
product differentiation with regard to LSPI.
[0012] This disclosure also relates in part to a method for
preventing or reducing low speed pre-ignition in an engine
lubricated with a lubricating oil by using as the lubricating oil a
formulated oil. The formulated oil has a composition comprising a
lubricating oil base stock as a major component; and at least one
zinc-containing compound or at least one antiwear agent, as a minor
component. The at least one antiwear agent comprises at least one
zinc dialkyl dithiophosphate compound derived at least in part from
a secondary alcohol. The engine exhibits greater than about 20%
reduced low speed pre-ignition, based on normalized low speed
pre-ignition (LSPI) counts per 25,000 engine cycles, engine
operation at 2000 revolutions per minute (RPM) and brake mean
effective pressure (BMEP) at 18 bar, as compared to low speed
pre-ignition performance achieved in an engine using a lubricating
oil that does not comprise at least one zinc-containing compound or
antiwear agent.
[0013] This disclosure further relates in part to a method for
preventing or reducing low speed pre-ignition in an engine
lubricated with a lubricating oil by using as the lubricating oil a
formulated oil as described above, in which the minor component
further comprises at least one boron-containing compound. The
boron-containing compound comprises at least one borated
dispersant, and/or a mixture of a boron-containing compound and a
non-borated dispersant.
[0014] This disclosure yet further relates in part to a method for
preventing or reducing low speed pre-ignition in an engine
lubricated with a lubricating oil by using as the lubricating oil a
formulated oil as described above, in which the minor component
further comprises at least one boron-containing compound and at
least one detergent. The boron-containing compound comprises at
least one borated dispersant, or a mixture of a boron-containing
compound and a non-borated dispersant. The detergent comprises at
least one alkaline earth metal salt of an organic acid, and the at
least one alkaline earth metal salt of an organic acid comprises at
least one magnesium salt of an organic acid.
[0015] 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 at least one zinc-containing compound or at
least one antiwear agent, as a minor component. The at least one
antiwear agent comprises at least one zinc dialkyl dithiophosphate
compound derived at least in part from a secondary alcohol.
[0016] The engine exhibits greater than about 20% reduced low speed
pre-ignition, based on normalized low speed pre-ignition (LSPI)
counts per 25,000 engine cycles, engine operation at 2000
revolutions per minute (RPM) and brake mean effective pressure
(BMEP) at 18 bar, as compared to low speed pre-ignition performance
achieved in an engine using a lubricating oil that does not
comprise at least one zinc-containing compound or antiwear
agent.
[0017] This disclosure further relates in part to a lubricating
engine oil as described above, in which the minor component further
comprises at least one boron-containing compound. The
boron-containing compound comprises at least one borated
dispersant, and/or a mixture of a boron-containing compound and a
non-borated dispersant.
[0018] This disclosure yet further relates in part to a lubricating
engine oil as described above, in which the minor component further
comprises at least one boron-containing compound and at least one
detergent. The boron-containing compound comprises at least one
borated dispersant, or a mixture of a boron-containing compound and
a non-borated dispersant. The detergent comprises at least one
alkaline earth metal salt of an organic acid, and the at least one
alkaline earth metal salt of an organic acid comprises at least one
magnesium salt of an organic acid.
[0019] It has been surprisingly found that, in accordance with this
disclosure, prevention or reduction of LSPI can be attained in an
engine lubricated with a lubricating oil by using as the
lubricating oil a formulated oil that includes at least one
zinc-containing compound or at least one antiwear agent, preferably
at least one zinc dialkyl dithiophosphate compound derived at least
in part from a secondary alcohol, present in a particular amount
(e.g., from about 0.1 weight percent to about 5.0 weight percent,
based on the total weight of the lubricating oil), in the
lubricating oil. In particular, for lubricating oil formulations
containing the at least one zinc-containing compound or at least
one antiwear agent, it has been surprisingly found that the engine
exhibits greater than about 20% reduced low speed pre-ignition,
based on normalized low speed pre-ignition (LSPI) counts per 25,000
engine cycles, engine operation at 2000 revolutions per minute
(RPM) and brake mean effective pressure (BMEP) at 18 bar, as
compared to low speed pre-ignition performance achieved in an
engine using a lubricating oil containing a minor component other
than the at least one zinc-containing compound or antiwear agent,
and in an amount other than the amount of the at least one
zinc-containing compound or antiwear agent, in the lubricating oil.
In addition, it has been surprisingly found that, in accordance
with this disclosure, reduction of LSPI can be attained in an
engine lubricated with a lubricating oil by using as the
lubricating oil a formulated oil that has a particular base stock
(e.g., a Gas-To-Liquids base stock or an ester base stock).
[0020] The disclosure also relates to a method for preventing or
reducing low speed pre-ignition in an engine lubricated with a
lubricating oil by using as the lubricating oil a formulated engine
oil, said formulated engine oil having a composition comprising a
lubricating oil base stock at from 70 to 85 wt. %; and at least one
zinc-containing compound or at least one antiwear agent, at a
loading to contribute from 400 ppm to about 2000 ppm of phosphorous
to the formulated engine oil; wherein said at least one antiwear
agent comprises at least one zinc dialkyl dithiophosphate compound
derived at least in part from a secondary alcohol; wherein the
engine exhibits greater than 50% reduced low speed pre-ignition,
based on normalized low speed pre-ignition (LSPI) counts per 25,000
engine cycles, engine operation at 2000 revolutions per minute
(RPM) and brake mean effective pressure (BMEP) at 18 bar, as
compared to low speed pre-ignition performance achieved in an
engine using a lubricating oil that does not comprise at least one
zinc-containing compound or at least one antiwear agent.
[0021] Other objects and advantages of the present disclosure will
become apparent from the detailed description that follows.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] All concentrations outlined in the figures are quoted on a
"as delivered" basis.
[0023] FIG. 1 shows formulation details in weight percent based on
the total weight percent of the formulation, of various lubricating
oil formulations, and the results of testing the various
lubricating oil formulations, as detailed in Example A.
[0024] FIG. 2 shows formulation details in weight percent based on
the total weight percent of the formulation, of various lubricating
oil formulations, as detailed in Example B.
[0025] FIG. 3 shows the results of testing the various lubricating
oil formulations set forth in FIG. 2, as detailed in Example B.
[0026] FIG. 4 shows formulation details in weight percent based on
the total weight percent of the formulation, of various lubricating
oil formulations, as detailed in Example C.
[0027] FIG. 5 shows the results of testing the various lubricating
oil formulations set forth in FIG. 4, as detailed in Example C.
[0028] FIG. 6 shows formulation details in weight percent based on
the total weight percent of the formulation, of the formulation
embodiments of this disclosure, as detailed in Example D.
[0029] FIG. 7 shows the expected results of testing the various
lubricating oil formulations of FIG. 6, as detailed in Example
D.
[0030] FIG. 8 shows formulation details in weight percent based on
the total weight percent of the formulation, of the formulation
embodiments of this disclosure, as detailed in Example E.
[0031] FIG. 9 shows the expected results of testing the various
lubricating oil formulations of FIG. 8, as detailed in Example
E.
[0032] FIG. 10 shows formulation details in weight percent based on
the total weight percent of the formulation, of the formulation
embodiments of this disclosure, as detailed in Example F.
[0033] FIG. 11 shows the expected results of testing the various
lubricating oil formulations of FIG. 10, as detailed in Example
F.
[0034] FIG. 12 shows the results of engine performance mapping as
detailed in Example A.
DETAILED DESCRIPTION
[0035] 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.
[0036] It has now been found that prevention or reduction of LSPI
can be attained in an engine lubricated with a lubricating oil by
using as the lubricating oil a formulated oil that includes at
least one zinc-containing compound or at least one antiwear agent,
preferably at least one zinc dialkyl dithiophosphate compound
derived at least in part from a secondary alcohol, present in a
particular amount (e.g., from about 0.1 weight percent to about 5.0
weight percent, based on the total weight of the lubricating oil),
in the lubricating oil. In addition, it has been found that
reduction of LSPI can be attained in an engine lubricated with a
lubricating oil by using as the lubricating oil a formulated oil
that has a particular base stock. The formulated oil preferably has
a composition comprising a lubricating oil base stock as a major
component, and at least one zinc-containing compound or at least
one antiwear agent, as a minor component. The at least one antiwear
agent comprises at least one zinc dialkyl dithiophosphate compound
derived at least in part from a secondary alcohol. The lubricating
oils of this disclosure are particularly advantageous as PVEO
products.
[0037] The lubricating oils of this disclosure are particularly
useful in internal combustion engines and, when used in internal
combustion engines, will prevent or minimize pre-ignition problems.
The lubricating oil compositions of this disclosure are useful in
lubricating gasoline-fueled, spark-ignited engines.
[0038] As described herein, the lubricant formulation chemistry of
this disclosure can be used to prevent or control the detrimental
effect of LSPI in engines which have already been designed or sold
in the marketplace as well as future engine technology. The
lubricant formulation chemistry of this disclosure removes barriers
for OEM technology and efficiency improvement, and enables further
development of downspeeded, turbocharged gasoline engines that is
currently being impeded by LSPI. The lubricant formulation solution
afforded by this disclosure for preventing or reducing LSPI enables
product differentiation with regard to LSPI.
Lubricating Oil Base Stocks
[0039] 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.
[0040] 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 about 80 to 120 and contain greater than about 0.03%
sulfur and/or less than about 90% saturates. Group II base stocks
have a viscosity index of between about 80 to 120, and contain less
than or equal to about 0.03% sulfur and greater than or equal to
about 90% saturates. Group III stocks have a viscosity index
greater than about 120 and contain less than or equal to about
0.03% sulfur and greater than about 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) Group V All other base oil stocks not
included in Groups I, II, III or IV
[0041] 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.
[0042] Group II and/or Group III hydroprocessed or hydrocracked
base stocks, including synthetic oils such as polyalphaolefins,
alkyl aromatics and synthetic esters are also well known base stock
oils.
[0043] Synthetic oils include hydrocarbon oil. Hydrocarbon oils
include oils such as polymerized and interpolymerized olefins
(polybutylenes, polypro-pylenes, 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.6, 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.
[0044] 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
about 250 to about 3,000, although PAO's may be made in viscosities
up to about 150 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 about C.sub.32 alphaolefins with the C.sub.6 to about
C.sub.16 alphaolefins, such as 1-hexene, 1-octene, 1-decene,
1-dodecene, 1-tetradecene, and the like, being preferred. The
preferred polyalphaolefins are poly-1-hexene, poly-1-octene,
poly-1-decene and poly-1-dodecene, 1 tetradecene, 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 base stocks 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. PAO fluids of particular use may
include 3.0 cSt, 3.4 cSt, and/or 3.6 cSt and combinations thereof
Bi-modal mixtures of PAO fluids having a viscosity range of 1.5 to
150 cSt may be used if desired.
[0045] 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. Nos. 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.
[0046] Other useful lubricant oil base stocks include wax isomerate
base stocks and base oils, comprising hydroisomerized waxy stocks
(e.g. waxy stocks such as gas oils, slack waxes, fuels hydrocracker
bottoms, etc.), hydroisomerized Fischer-Tropsch waxes,
Gas-to-Liquids (GTL) base stocks and base oils, and other wax
isomerate hydroisomerized base stocks and base oils, or mixtures
thereof Fischer-Tropsch waxes, the high boiling point residues of
Fischer-Tropsch synthesis, are highly paraffinic hydrocarbons with
very low sulfur content. The hydroprocessing used for the
production of such base stocks may use an amorphous
hydrocracking/hydroisomerization catalyst, such as one of the
specialized lube hydrocracking (LHDC) catalysts or a crystalline
hydrocracking/hydroisomerization catalyst, preferably a zeolitic
catalyst. For example, one useful catalyst is ZSM-48 as described
in U.S. Pat. No. 5,075,269, the disclosure of which is incorporated
herein by reference in its entirety. Processes for making
hydrocracked/hydroisomerized distillates and
hydrocracked/hydroisomerized waxes are described, for example, in
U.S. Pat. Nos. 2,817,693; 4,975,177; 4,921,594 and 4,897,178 as
well as in British Patent Nos. 1,429,494; 1,350,257; 1,440,230 and
1,390,359. Each of the aforementioned patents is incorporated
herein in their entirety. Particularly favorable processes are
described in European Patent Application Nos. 464546 and 464547,
also incorporated herein by reference. Processes using
Fischer-Tropsch wax feeds are described in U.S. Pat. Nos. 4,594,172
and 4,943,672, the disclosures of which are incorporated herein by
reference in their entirety.
[0047] Gas-to-Liquids (GTL) base oils, Fischer-Tropsch wax derived
base oils, and other wax-derived hydroisomerized (wax isomerate)
base oils be advantageously used in the instant disclosure, and may
have useful kinematic viscosities at 100.degree. C. of about 3 cSt
to about 50 cSt, preferably about 3 cSt to about 30 cSt, more
preferably about 3.5 cSt to about 25 cSt, as exemplified by GTL 4
with kinematic viscosity of about 4.0 cSt at 100.degree. C. and a
viscosity index of about 141. These Gas-to-Liquids (GTL) base oils,
Fischer-Tropsch wax derived base oils, and other wax-derived
hydroisomerized base oils may have useful pour points of about
-20.degree. C. or lower, and under some conditions may have
advantageous pour points of about -25.degree. C. or lower, with
useful pour points of about -30.degree. C. to about -40.degree. C.
or lower. Useful compositions of Gas-to-Liquids (GTL) base oils,
Fischer-Tropsch wax derived base oils, and wax-derived
hydroisomerized base oils are recited in U.S. Pat. Nos. 6,080,301;
6,090,989, and 6,165,949 for example, and are incorporated herein
in their entirety by reference.
[0048] The hydrocarbyl aromatics can be used as base oil or base
oil component and can be any hydrocarbyl molecule that contains at
least about 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 about C.sub.6 up to about
C.sub.60 with a range of about C.sub.8 to about C.sub.20 often
being preferred. A mixture of hydrocarbyl groups is often
preferred, and up to about 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 about
5% of the molecule is comprised of an above-type aromatic moiety.
Viscosities at 100.degree. C. of approximately 3 cSt to about 50
cSt are preferred, with viscosities of approximately 3.4 cSt to
about 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 about 2% to about 25%, preferably about 4% to
about 20%, and more preferably about 4% to about 15%, depending on
the application.
[0049] Alkylated aromatics such as the hydrocarbyl aromatics of the
present disclosure may be produced by well-known Friedel-Crafts
alkylation of aromatic compounds. See Friedel-Crafts and Related
Reactions, Olah, G. A. (ed.), Inter-science Publishers, New York,
1963. For example, an aromatic compound, such as benzene or
naphthalene, is alkylated by an olefin, alkyl halide or alcohol in
the presence of a Friedel-Crafts catalyst. See Friedel-Crafts and
Related Reactions, Vol. 2, part 1, chapters 14, 17, and 18, See
Olah, G. A. (ed.), Inter-science Publishers, New York, 1964. Many
homogeneous or heterogeneous, solid catalysts are known to one
skilled in the art. The choice of catalyst depends on the
reactivity of the starting materials and product quality
requirements. For example, strong acids such as AlCl.sub.3,
BF.sub.3, or HF may be used. In some cases, milder catalysts such
as FeCl.sub.3 or SnC1.sub.4 are preferred. Newer alkylation
technology uses zeolites or solid super acids.
[0050] 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 mono-carboxylic 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.
[0051] 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 about 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.
[0052] 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 about 5 to about 10 or more
carbon atoms. These esters are widely available commercially, for
example, the Mobil P-41 and P-51 esters of ExxonMobil Chemical
Company.
[0053] Preferred synthetic esters useful in this disclosure have a
kinematic viscosity at 100.degree. C. of about 3 cSt to about 50
cSt, preferably about 3 cSt to about 30 cSt, more preferably about
3.5 cSt to about 25 cSt, and even more preferably about 2 cSt to
about 8 cSt. Group V base oils useful in this disclosure preferably
comprise an ester at a concentration of about 2% to about 20%,
preferably from about 5% to about 15%.
[0054] Also useful are esters derived from renewable material such
as coconut, palm, rapeseed, soy, sunflower and the like. These
esters may be monoesters, di-esters, polyol esters, complex esters,
or mixtures thereof. These esters are widely available
commercially, for example, the Mobil P-51 ester of ExxonMobil
Chemical Company.
[0055] Engine oil formulations containing renewable esters are
included in this disclosure. For such formulations, the renewable
content of the ester is typically greater than about 70 weight
percent, preferably more than about 80 weight percent and most
preferably more than about 90 weight percent.
[0056] 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.
[0057] 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.
[0058] 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.
[0059] 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 about 2 mm.sup.2/s to about 50 mm.sup.2/s
(ASTM D445). They are further characterized typically as having
pour points of -5.degree. C. to about -40.degree. C. or lower (ASTM
D97). They are also characterized typically as having viscosity
indices of about 80 to about 140 or greater (ASTM D2270).
[0060] 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.
[0061] 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).
[0062] 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 about 10 ppm, and more typically
less than about 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.
[0063] 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, and mixtures
thereof, due to their exceptional volatility, stability,
viscometric and cleanliness features. The above base stocks when
used in combination with the additive components disclosed in this
disclosure can be used to formulate SAE 0W-8, SAE 0W-12, SAE 0W-16,
SAE 0W-20, SAE 0W-30, SAE 0W-40, SAE 5W-12, SAE 5W-16, SAE 5W-20,
SAE 5W-30, and SAE 10W-40 products with exceptional LSPI
performance. These base stocks when used in combination with the
additive components disclosed in this disclosure are particularly
effective in formulating SAE 0W-8, SAE 0W-12, SAE 0W-16, SAE 0W-20,
SAE 0W-30, SAE 0W-40, and SAE 5W-30 oils with exceptional LSPI
performance.
[0064] 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 about 50 to about 99 weight
percent, preferably from about 70 to about 95 weight percent, and
more preferably from about 85 to about 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 about 2.5 cSt
to about 12 cSt (or mm.sup.2/s) at 100.degree. C. and preferably of
about 2.5 cSt to about 9 cSt (or mm.sup.2/s) at 100.degree. C., and
more preferably of about 3.5 cSt to about 7 cSt (or mm.sup.2/s) at
100.degree. C. and even more preferred in some application of 3.5
cSt to about 5 cSt (or mm.sup.2/s) at 100.degree. C. Mixtures of
synthetic and natural base oils may be used if desired. Mixtures of
Group III, IV, and V may be preferably used if desired.
Antiwear Agent
[0065] 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 a useful component of the
lubricating oils of this disclosure. ZDDP can be derived from
primary alcohols, secondary alcohols or mixtures thereof. The
preferred ZDDP compounds generally are represented by the
formula
Zn[SP(S)(OR.sup.1)(OR.sup.2)].sub.2
wherein R.sup.1 and R.sup.2 are independently primary and/or
secondary C.sub.1 to C.sub.8 alkyl groups. A mixture of primary
alcohol(1.degree.) derived ZDDP and secondary alcohol) (2.degree.
derived ZDDP can be used. The R.sup.1 and R.sup.2 substituents can
independently be C.sub.1-C.sub.18 alkyl groups, preferably
C.sub.2-C.sub.12 alkyl groups. Preferably, R.sup.1 and R.sup.2 are
independently primary or secondary C.sub.1 to C.sub.8 alkyl groups,
provided at least one of R.sup.1 and R.sup.2 is a secondary C.sub.1
to C.sub.8 alkyl group. Mixtures of primary alcohol derived ZDDP
and secondary alcohol derived ZDDP where R.sup.1 and R.sup.2 are
C.sub.1 to C.sub.8 alkyl groups can be used. These alkyl groups may
be straight chain or branched. Alkyl aryl groups may also be
used.
[0066] 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", "LZ 1389" and "LZ 1371",
from for example Chevron Oronite under the trade designation "OLOA
262" from for example Afton Chemical under the trade designation
"HITEC 7169 and from for example Infineum under the trade
designation Infineum C9417, and Infineum C9414.
[0067] Preferably, the primary or secondary C.sub.1 to C.sub.8
alkyl groups of the zinc dialkyl dithiophosphate compound are
derived in part from an alcohol selected from the group consisting
of: 2-propanol (C3), 1-butanol (n-C4), 1-isobutanol (1-i-C4),
2-butanol (2-C4), 1-pentanol (primary C-5), 3-methyl-1-butanol
(primary C-5), 2-pentanol (C5), 3-pentanol (C5), 3-methyl-2-butanol
(C5), 1-hexanol (primary C6), 4-methyl-1-pentanol (primary C6),
4-methyl-2-pentanol (C6), and 2-ethyl-1-hexanol (primary C8), and
mixtures thereof. In some cases ZDDP derived from alcohols having
an average carbon number of 5 and less are desirable. In some cases
ZDDP derived from alcohols having an average carbon number of
greater than 5 are desirable. Table 1 below shows alcohol mixtures
used to make ZDDP which can be advantageously used in this
disclosure.
TABLE-US-00002 TABLE 1 Alcohol Mixtures Useful in Preparing ZDDPs
(wt %) i-C3, 2-C4, - 1-i-C4, n-C4, - i-C5 n-C5 i-C6 C6 C8 Secondary
Secondary Primary Primary Secondary Primary Secondary Primary
Primary 20.2% 4.0% 75.7% 8.4% 3.2% 11.7% 76.6% 45.2% 6.2% 19.4%
1.4% 8.8% 19.1% 42.3% 2.4% 55.3% 23.2% 13.3% 63.6% 5.7% 2.3% 92.1%
4.6% 63.1% 32.3% 4.1% 2.4% 52.6% 40.9% 7.7% 1.8% 90.6% 9.1% 0.4%
89.3% 0.4% 0.8% 42.0% 0.5% 56.5% 0.2% 0.9% 33.9% 66.1% 0.3% 0.2%
99.6% 85.6% 14.4%
[0068] The R.sup.1 and R.sup.2 primary or secondary alkyl groups of
the zinc dialkyl dithiophosphate compound, and the amount of the
zinc dialkyl dithiophosphate compound having the R.sup.1 and
R.sup.2 primary or secondary alkyl groups in the lubricating oil,
are sufficient for an engine to exhibit reduced low speed
pre-ignition, as compared to low speed pre-ignition performance
achieved in an engine using a lubricating oil containing a minor
component other than the particular zinc dialkyl dithiophosphate
compound, and in an amount other than the amount of the particular
zinc dialkyl dithiophosphate compound, in the lubricating oil.
[0069] In general, the ZDDP can be used in amounts of from about
0.4 weight percent to about 1.2 weight percent, preferably from
about 0.5 weight percent to about 1.0 weight percent, and more
preferably from about 0.6 weight percent to about 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 primary, secondary or mixture ZDDP and present in an amount of
from about 0.6 to 1.0 weight percent of the total weight of the
lubricating oil.
[0070] Preferably, the zinc dialkyl dithiophosphate compounds
having the R.sup.1 and R.sup.2 primary or secondary alkyl groups,
in which the R.sup.1 and R.sup.2 primary or secondary alkyl groups
are derived from 2-ethyl-1-hexanol (Primary C8), are present in an
amount of from about 0.1 weight percent to about 5.0 weight
percent, preferably from about 0.1 to about 1.2 weight percent, and
more preferably from about 0.2 to about 0.8 weight percent, based
on the total weight of the lubricating oil.
[0071] Preferably, the zinc dialkyl dithiophosphate compounds
having the R.sup.1 and R.sup.2 primary or secondary alkyl groups,
in which the R.sup.1 and R.sup.2 primary or secondary alkyl groups
are derived from 4-methyl-2-pentanol (i-C6), are present in an
amount of from about 0.1 weight percent to about 5.0 weight
percent, preferably from about 0.1 to about 1.2 weight percent, and
more preferably from about 0.2 to about 0.8 weight percent, based
on the total weight of the lubricating oil.
[0072] Preferably, the zinc dialkyl dithiophosphate compound is
derived from a C.sub.3 to C.sub.8 secondary alcohol, or a mixture
thereof. Also, preferably, the zinc dialkyl dithiophosphate
compound is derived from a mixture of a C.sub.1 to C.sub.8 primary
alcohol and a C.sub.1 to C.sub.8 secondary alcohol.
[0073] The zinc content contributed by the zinc-containing compound
or antiwear agent in the lubricating oil ranges from about 500 ppm
to about 2000 ppm, preferably from about 600 ppm to about 900
ppm.
[0074] The phosphorus content contributed by the zinc-containing
compound or antiwear agent in the lubricating oil ranges from about
400 ppm to about 2000 ppm, preferably from about 500 ppm to about
900 ppm. The phosphorus derived from the secondary ZDDP is
preferably from 0 to 900 ppm and more preferably from 400 to 900
ppm.
[0075] The zinc to phosphorus ratio in the lubricating oil ranges
from about 1.0 to about 2.0, preferably from about 1.1 to about
1.9.
[0076] The ratio of total metals provided by the detergent to total
metals provided by the zinc-containing compound and antiwear agent
is from about 0.8 to 4.8, preferably from about 1.4 to 4.0, and
more preferably from about 1.5 to 3.7.
[0077] Illustrative zinc-containing compounds useful in this
disclosure include, for example, zinc carboxylates, zinc
sulfonates, zinc acetates, zinc napthenates, zinc alkenyl
succinates, zinc acid phosphate salts, zinc phenates, zinc
salicylates, and the like.
[0078] In accordance with this disclosure, an engine exhibits
greater than about 20%, preferably greater than about 25%, and more
preferably greater than about 30%, reduced low speed pre-ignition,
based on normalized low speed pre-ignition (LSPI) counts per 25,000
engine cycles, engine operation at 2000 revolutions per minute
(RPM) and brake mean effective pressure (BMEP) at 18 bar, as
compared to low speed pre-ignition performance achieved in an
engine using a lubricating oil containing a minor component other
than the at least one zinc-containing compound or at least one
antiwear agent, and in an amount other than the amount of the at
least one zinc-containing compound or at least one antiwear agent,
in the lubricating oil. Similar or even greater reduced low speed
pre-ignition can be attained using mixtures of the at least one
zinc-containing compound or at least one antiwear agent with at
least one boron-containing compound and/or with at least one
detergent, as described herein.
[0079] Preferably, the zinc dialkyl dithiophosphate compounds
having the R.sup.1 and R.sup.2 primary or secondary alkyl groups,
in which the R.sup.1 and R.sup.2 primary or secondary alkyl groups
are derived from 2-propanol (C3), 2-butanol (2-C4), 1-iso-butanol
(1-i-C4), or n-pentanol (n-C5), are present in an amount of from
about 0.1 weight percent to about 5.0 weight percent, preferably
from about 0.1 to about 1.2 weight percent, and more preferably
from about 0.2 to about 0.8 weight percent, based on the total
weight of the lubricating oil.
[0080] The zinc-containing compound or antiwear agent concentration
in the lubricating oils of this disclosure can range from about 0.1
to about 5.0 weight percent, preferably about 0.2 to 2.0 weight
percent, and more preferably from about 0.2 weight percent to about
1.0 weight percent, based on the total weight of the lubricating
oil. In the presence of magnesium detergents and boron containing
additives, only small amounts of ZDDP are needed to give
exceptionally low LSPI counts. In such presence of magnesium and
boron containing compounds as little as 0.1% to 1.0 wt. % ZDDP (100
ppm P to 1000 ppm P phosphorus in the formulated engine oil) will
provide unexpected improvements in LSPI performance. At higher ash
levels and higher TBN levels, ZDDP levels of 1.1 to 4.0 wt. % can
provide unexpected improvements in LSPI performance. For SAE xW-40
and xW-50 oils (x=0, 5, 10, 15), ZDDP levels of 1.1 to 4.0 wt. %
are especially useful to provide unexpected improvements in LSPI
performance.
Dispersants
[0081] 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 or little 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.
[0082] At least one boron-containing compound is useful in this
disclosure. The boron-containing compound comprises at least one
borated dispersant, or a mixture of a boron-containing compound and
a non-borated dispersant. Effective ranges of boron in the
formulation from the borated dispersant or other boron containing
additive(s) are 30 ppm to 1500 ppm, or more a preferred range of 60
ppm to 1000 ppm, or a most preferred range of 120 ppm to 600
ppm.
[0083] Preferably, the boron-containing compound includes, for
example, a borated succinimide, a borated succinate ester, a
borated succinate ester amide, a borated Mannich base, and mixtures
thereof.
[0084] The non-borated dispersant includes, for example, a
hydrocarbyl succinic anhydride derived succinimide or succinate
ester with a coupling agent, wherein the coupling agent comprises a
boron-containing compound.
[0085] Preferably, boron is provided to the lubricating oil by a
mixture of an organic or inorganic boron-containing compound and a
borated succinimide, a borated succinate ester, a borated succinate
ester amide, a Mannich base ester, or mixtures thereof. The borated
succinimide is preferably a mono succinimide, bis-succinimide, or a
mixture thereof. Effective boron containing compounds include
borated hydrocarbyl succinimides, including those derived for
hydrocarbyl sources where number average molecular weight (M.sub.n)
is between 50 and 5000 Daltons, borated hydrocarbyl succinates,
borated hydrocarbyl substituted Mannich bases, borated alcohols,
borated alkoxylated alcohols, borated hydrocarbyl diols, borated
hydrocarbyl amines, borated hydrocarbyl diamines, borated
hydrocarbyl triamines, borated alkoxylated hydrocarbyl amines,
borated alkoxylated hydrocarbyl amides, borated hydrocarbyl
containing hydroxyl esters, borated hydrocarbyl substituted
oxazolines, borated hydrocarbyl substituted imidazolones, and the
like and mixtures of organic borates. Borates of --N--H, and/or
--OH derived moieties can also be used. These borates can be
inorganic, or organic moiety derived borates. Borates can be
prepared using boric acid, borated alcohols and the like. These
borates can be used at concentrations to provide 60-1200 ppm boron
in the engine oil formulations, 60-240 ppm boron, 240-1200 ppm
boron, 240-500 ppm boron, or 60-120 ppm boron to produce unexpected
surprising improvement in LSPI performance, as desired.
[0086] The ratio of total zinc from the zinc-containing compound
and antiwear agent plus total alkaline earth metal from the
detergent divided by the total boron from the boron-containing
compound and borated dispersant, in the lubricating oil, is from
about 9.2 to 45, preferably from about 11 to 15.
[0087] 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. In some exemplifications, the hydrocarbon
chain can range from 6 to 50 carbon atoms.
[0088] 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; 3,2145,707; 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.
[0089] 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,
although on occasion, having a hydrocarbon substituent between
20-50 carbon atoms can be useful.
[0090] 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 ethylene
amines (e.g., Diethylene triamine, triethylene tetraamine,
tetraethylene pentaamine, hexaethylene heptamine, heptaethylene
octaamine, and the like) Polyethylene amines containing
Tetraethylene Pentaamine (TEPA) are often preferred. High molecular
weight polyethylene amine bottoms comprising hexaethylene
heptamine, and heptaethylene octaamine can also be used. The ratio
of hydrocarbyl substituted succinic anhydride to polyethylene
amines can vary from about 1:1 to about 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.
[0091] 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.
[0092] 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.
[0093] The molecular weight of the hydrocarbyl substituted succinic
anhydrides used in the preceding paragraphs will typically range
between 800 and 2,500 Daltons or more. 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 about 0.1 to about 5
moles of boron per mole of dispersant reaction product.
[0094] 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.
[0095] 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.RTM..sub.2 group-containing reactants.
[0096] 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.
[0097] Preferred dispersants include 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 M.sub.n of
from about 500 to about 5000 Daltons, or from about 1000 to about
3000 Daltons, or about 1000 to about 2000 Daltons, or a mixture of
such hydrocarbylene groups, often with high terminal vinylic
groups. Preferred dispersants useful in this disclosure are
characterized having a M.sub.n of about 800 to 1700 Daltons for low
molecular weight, and a M.sub.n of about 1700 to about 5000 Daltons
or greater for high molecular weight. 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 about 0.1 to 20 weight percent, preferably
about 0.5 to 8 weight percent, or more preferably 0.5 to 4 weight
percent. The hydrocarbon portion of the dispersant atoms can range
from C.sub.60 to C.sub.400, or from C.sub.70 to C.sub.300, or from
C.sub.70 to C.sub.200. These dispersants may contain both neutral
and basic nitrogen, and mixtures of both.
[0098] The ratio of basic to non-basic nitrogen in the dispersant
can range from 1 to 5, to 5 to 1 or more preferably from 1 to 2, to
2 to 1. Dispersants can be end-capped by borates and/or cyclic
carbonates and or any carboxylic acid such as hydrocarbyl
carboxylic acids or hydrocarbyl carboxylic acid anhydrides.
[0099] For lubricating oil formulations containing at least one
boron-containing compound and at least one zinc-containing compound
or antiwear agent in accordance with this disclosure, an engine
exhibits greater than about 20%, preferably greater than about 25%,
and more preferably greater than about 30%, reduced low speed
pre-ignition, based on normalized low speed pre-ignition (LSPI)
counts per 25,000 engine cycles, engine operation at 2000
revolutions per minute (RPM) and brake mean effective pressure
(BMEP) at 18 bar, as compared to low speed pre-ignition performance
achieved in an engine using a lubricating oil containing a minor
component other than the at least one boron-containing compound and
at least one zinc-containing compound or antiwear agent, and in an
amount other than the amount of the at least one boron-containing
compound and at least one zinc-containing compound or antiwear
agent, in the lubricating oil.
[0100] As used herein, the dispersant concentrations are given on
an "as delivered" basis. Typically, the active dispersant is
delivered with a process oil. The "as delivered" dispersant
typically contains from about 20 weight percent to about 80 weight
percent, or from about 40 weight percent to about 60 weight
percent, of active dispersant in the "as delivered" dispersant
product.
Detergents
[0101] Illustrative detergents useful in this disclosure include,
for example, alkaline earth metal detergents, or mixtures of
alkaline earth metal detergents. A typical alkaline earth metal
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 derived from an organic acid such as a sulfur
acid, carboxylic acid, phosphorous acid, phenol, or mixtures
thereof. The counterion is an alkaline earth metal. Preferably, the
detergent comprises at least one alkaline earth metal salt of an
organic acid, and the at least one alkaline earth metal salt of an
organic acid comprises at least one magnesium salt of an organic
acid.
[0102] Preferred detergents useful in the lubricating oils of this
disclosure are selected from the group consisting of an alkaline
earth metal sulfonate, an alkaline earth metal carboxylate (e.g.,
salicylate), an alkaline earth metal phenate, an alkaline earth
metal phosphate, and mixtures thereof. The alkaline earth metal
sulfonate, alkaline earth metal carboxylate, alkaline earth metal
phenate, alkaline earth metal phosphate, and mixtures thereof, and
the amount of the alkaline earth metal sulfonate, alkaline earth
metal carboxylate, alkaline earth metal phenate, alkaline earth
metal phosphate, and mixtures thereof in the lubricating oil, are
sufficient for the engine to exhibit reduced low speed
pre-ignition, as compared to low speed pre-ignition performance
achieved in an engine using a lubricating oil containing a
detergent other than the alkaline earth metal sulfonate, alkaline
earth metal carboxylate, alkaline earth metal phenate, alkaline
earth metal phosphate, and mixtures thereof, and in an amount other
than the amount of the alkaline earth metal sulfonate, alkaline
earth metal carboxylate, alkaline earth metal phenate, alkaline
earth metal phosphate, and mixtures thereof, in the lubricating
oil.
[0103] The alkaline earth metal detergents useful in this
disclosure can be prepared by convention methods known in the
art.
[0104] Alkaline earth metal sulfonates are a preferred class of
detergents. Sulfur acids useful in preparing the alkaline earth
metal sulfonates include sulfonic acids, thiosulfonic, sulfinic,
sulfenic, partial ester sulfuric, sulfurous and thiosulfuric acids.
Sulfonic acids are preferred.
[0105] The sulfonic acids are generally petroleum sulfonic acids or
synthetically prepared alkaryl sulfonic acids. Among the petroleum
sulfonic acids, the most useful products are those prepared by the
sulfonation of suitable petroleum fractions with a subsequent
removal of acid sludge, and purification. Synthetic alkaryl
sulfonic acids are prepared usually from alkylated benzenes such as
the Friedel-Crafts reaction products of benzene and polymers such
as tetrapropylene. The following are specific examples of sulfonic
acids useful in preparing the alkaline earth metal sulfonate
detergents useful in this disclosure. It is to be understood that
such examples serve also to illustrate the alkaline earth metal
salts of such sulfonic acids. In other words, for every sulfonic
acid enumerated, it is intended that the corresponding basic
alkaline earth metal salts thereof are also understood to be
illustrated.
[0106] Such sulfonic acids include mahogany sulfonic acids, bright
stock sulfonic acids, petrolatum sulfonic acids, mono- and
polywax-substituted naphthalene sulfonic acids, cetylchlorobenzene
sulfonic acids, cetylphenol sulfonic acids, cetylphenol disulfide
sulfonic acids, cetoxycapryl benzene sulfonic acids, dicetyl
thianthrene sulfonic acids, dilauryl beta-naphthol sulfonic acids,
dicapryl nitronaphthalene sulfonic acids, saturated paraffin wax
sulfonic acids, unsaturated paraffin wax sulfonic acids,
hydroxy-substituted paraffin wax sulfonic acids, tetra-isobutylene
sulfonic acids, tetra-amylene sulfonic acids, chloro-substituted
paraffin wax sulfonic acids, nitroso-substituted paraffin wax
sulfonic acids, petroleum naphthene sulfonic acids,
cetylcyclopentyl sulfonic acids, lauryl cyclohexyl sulfonic acids,
mono- and polywax-substituted cyclohexyl sulfonic acids,
dodecylbenzene sulfonic acids, "dimer alkylate" sulfonic acids, and
the like.
[0107] Alkyl-substituted benzene sulfonic acids wherein the alkyl
group contains at least 8 carbon atoms including dodecyl benzene
"bottoms" sulfonic acids are useful in this disclosure. The latter
are acids derived from benzene which has been alkylated with
propylene tetramers or isobutene trimers to introduce 1, 2, 3, or
more branched-chain C.sub.12 substituents on the benzene ring.
Dodecyl benzene bottoms, principally mixtures of mono- and
di-dodecyl benzenes, are available as by-products from the
manufacture of household detergents.
[0108] Preferred alkaline earth metal sulfonates include magnesium
sulfonate, calcium sulfonate, and mixtures thereof.
[0109] Alkaline earth phenates are a useful class of detergents.
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 or
mixtures thereof. 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 and can be used from 0.5 to 6 weight
percent. 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.
[0110] Preferred phenate compounds include, for example, magnesium
phenate, calcium phenate, an overbased phenate compound, a
sulfurized/carbonated calcium phenate compound, and mixtures
thereof
[0111] Alkaline earth metal salts of carboxylic acids are also
useful as detergents. These carboxylic acid detergents may be
prepared by reacting a basic alkaline earth 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.
[0112] 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 about 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 or
magnesium.
[0113] Hydrocarbyl-substituted salicylic acids may be prepared from
phenols by the Kolbe reaction (see U.S. Pat. No. 3,595,791). The
alkaline earth metal salts of the hydrocarbyl-substituted salicylic
acids may be prepared by double decomposition of an alkaline earth
metal salt in a polar solvent such as water or alcohol.
[0114] Preferred carboxylate compounds comprise a noncarbonated
magnesium salicylate (carboxylate); a carbonated magnesium
salicylate (carboxylate); a noncarbonated calcium salicylate
(carboxylate); a carbonated calcium salicylate (carboxylate); and
mixtures thereof.
[0115] Salts that contain a substantially stoichiometric amount of
the alkaline earth metal are described as neutral salts and have a
total base number (TBN, as measured by ASTM D2896) of from 0 to
100. Many compositions are overbased, containing large amounts of a
metal base that is achieved by reacting an excess of an alkaline
earth metal compound with an acidic gas (such as carbon dioxide).
Useful detergents can be neutral, mildly overbased, or highly
overbased. These detergents can be used in mixtures of neutral,
overbased, highly overbased magnesium salicylate, sulfonates,
phenates and/or calcium salicylate, sulfonates, and phenates. The
TBN ranges can vary from low TBN of about 0 to 100, medium TBN of
about 100 to 200, and high TBN of about 200 to as high as 600,
including as low as 0 to as high as 600. Mixtures of low, medium,
high TBN can be used, along with mixtures of calcium and magnesium
metal based detergents, and including sulfonates, phenates,
salicylates, and carboxylates. Further examples of mixed TBN
detergents can be found as described in U.S. Pat. No. 7,704,930,
which is incorporated herein by reference. A detergent mixture with
a metal ratio of 1, in conjunction of a detergent with a metal
ratio of 2, and as high as a detergent with a metal ratio of 5 or
10 or 15, can be used. Borated detergents can also be used.
[0116] Alkaline earth metal phosphates may also be used as
detergents and are known in the art.
[0117] 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.
[0118] Suitable detergents include magnesium sulfonates, calcium
sulfonates, calcium phenates, magnesium phenates, calcium
salicylates, magnesium salicylates, and other related components
(including borated detergents), and mixtures thereof. Preferred
detergents include magnesium sulfonate, calcium sulfonate,
magnesium phenate, calcium phenate, magnesium salicylate, calcium
salicylate, and mixtures thereof.
[0119] Other illustrative detergents that may be used in
combination with the alkaline earth metal detergents include, for
example, alkali metal detergents, or mixtures of alkali metal
detergents.
[0120] In a detergent comprising a mixture of a magnesium salt of
an organic acid and a calcium salt of an organic acid, the
detergent ratio of magnesium metal to calcium metal ranges from
about 1:0 to about 1:10, preferably from about 1:0 to about
1:4.
[0121] The magnesium and alkaline earth metal contributed by the
detergent is present in the lubricating oil in an amount from about
500 ppm to about 5000 ppm, preferably from about 1000 ppm to about
2500 ppm. The magnesium contributed by the detergent is present in
the lubricating oil in an amount from about 100 ppm to about 3000
ppm, preferably from about 300 ppm to about 2500 ppm, and more
preferably from about 750 ppm to about 2000 ppm.
[0122] The total base number (TBN), as measured by ASTM D2896,
contributed by the detergent ranges from about 2 mg KOH/g to about
17 mg KOH/g, preferably from about 4 mg KOH/g to about 14 mg KOH/g.
The TBN contributed by the magnesium detergent ranges from about 2
mg KOH/g to about 17 mg KOH/g, preferably from about 3 mg KOH/g to
about 14 mg KOH/g
[0123] The sulfated ash contributed by the detergent ranges from
about 0.4 to about 1.7 wt %, preferably from about 0.5 to about 1.6
wt %, and more preferably from about 0.6 to about 1.0 wt %. The
sulfated ash contributed by the magnesium detergent ranges from
about 0.3 to about 1.8 wt %, preferably from about 0.4 to about 1.6
wt %, and more preferably from about 0.6 to about 1.0 wt %. The
lubricating engine oil of this disclosure preferably contains less
than about 1.6 percent by weight sulfated ash and/or more
preferably contains less than about 4000 ppm of magnesium. At
higher engine oil sulfated ash at or above 1.2% ash (with the use
of a magnesium detergent) greater than a 95% reduction in LSPI
counts is achieved. At sulfated ash levels <1.2% with the use of
a magnesium detergent, LSPI can be entirely eliminated.
[0124] For lubricating oil formulations containing at least one
zinc-containing compound or antiwear agent and at least one
detergent in accordance with this disclosure, an engine exhibits
greater than about 50%, preferably greater than about 75%, and more
preferably greater than about 95%, reduced low speed pre-ignition,
based on normalized low speed pre-ignition (LSPI) counts per 25,000
engine cycles, engine operation at 2000 revolutions per minute
(RPM) and brake mean effective pressure (BMEP) at 18 bar, as
compared to low speed pre-ignition performance achieved in an
engine using a lubricating oil containing a minor component other
than the at least one zinc-containing compound or antiwear agent
and at least one detergent, and in an amount other than the amount
of the at least one zinc-containing compound or antiwear agent and
at least one detergent, in the lubricating oil.
[0125] Also, for lubricating oil formulations containing at least
one zinc-containing compound or antiwear agent, at least one
boron-containing compound, and at least one detergent in accordance
with this disclosure, an engine exhibits greater than about 50%,
preferably greater than about 75%, and more preferably greater than
about 95%, reduced low speed pre-ignition, based on normalized low
speed pre-ignition (LSPI) counts per 25,000 engine cycles, engine
operation at 2000 revolutions per minute (RPM) and brake mean
effective pressure (BMEP) at 18 bar, as compared to low speed
pre-ignition performance achieved in an engine using a lubricating
oil containing a minor component other than the at least one
zinc-containing compound or antiwear agent, at least one
boron-containing compound, and at least one detergent, and in an
amount other than the amount of the at least one zinc-containing
compound or antiwear agent, at least one boron-containing compound,
and at least one detergent, in the lubricating oil.
[0126] The detergent concentration in the lubricating oils of this
disclosure can range from about 1.0 to about 6.0 weight percent,
preferably about 2.0 to 5.0 weight percent, and more preferably
from about 2.0 weight percent to about 4.0 weight percent, based on
the total weight of the lubricating oil. In the lubricating oils of
this disclosure, the amount of alkaline earth metal sulfonate
preferably can range from about 0.5 to about 2.5 weight percent,
preferably from about 0.5 to about 2.0 weight percent, and more
preferably from about 0.5 to about 1.5 weight percent, based on the
total weight of the lubricating oil. In the lubricating oils of
this disclosure, the amount of alkaline earth metal phenate
preferably can range from about 0.5 to about 2.5 weight percent,
preferably from about 0.5 to about 2.0 weight percent, and more
preferably from about 0.5 to about 1.5 weight percent, based on the
total weight of the lubricating oil. In the lubricating oils of
this disclosure, the amount of alkaline earth metal carboxylate can
range from about 1.0 to about 4.0 weight percent, preferably from
about 1.0 to about 3.0 weight percent, and more preferably from
about 1.5 to about 2.5 weight percent, based on the total weight of
the lubricating oil. In the lubricating oils of this disclosure,
the amount of alkaline earth metal phosphate can range from about
1.0 to about 4.0 weight percent, preferably from about 1.0 to about
3.0 weight percent, and more preferably from about 1.5 to about 2.5
weight percent, based on the total weight of the lubricating
oil.
[0127] As used herein, the detergent concentrations are given on an
"as delivered" basis. Typically, the active detergent is delivered
with a process oil. The "as delivered" detergent typically contains
from about 20 weight percent to about 80 weight percent, or from
about 40 weight percent to about 60 weight percent, of active
detergent in the "as delivered" detergent product.
Other Additives
[0128] 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 other antiwear agents, other dispersants, other
detergents, corrosion inhibitors, rust inhibitors, metal
deactivators, 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); see also U.S. Pat. No. 7,704,930, the
disclosure of which is incorporated herein in its entirety. These
additives are commonly delivered with varying amounts of diluent
oil, that may range from 5 weight percent to 50 weight percent.
[0129] 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.
Viscosity Index Improvers
[0130] Viscosity index improvers (also known as VI improvers,
viscosity modifiers, and viscosity improvers) can be included in
the lubricant compositions of this disclosure.
[0131] 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.
[0132] 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
about 10,000 to 1,500,000, more typically about 20,000 to
1,200,000, and even more typically between about 50,000 and
1,000,000.
[0133] 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.
[0134] 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".
[0135] In an embodiment of this disclosure, the viscosity index
improvers may be used in an amount of less than about 2.0 weight
percent, preferably less than about 1.0 weight percent, and more
preferably less than about 0.5 weight percent, based on the total
weight of the formulated oil or lubricating engine oil. Viscosity
improvers are typically added as concentrates, in large amounts of
diluent oil.
[0136] In another embodiment of this disclosure, the viscosity
index improvers may be used in an amount of from 0.25 to about 2.0
weight percent, preferably 0.15 to about 1.0 weight percent, and
more preferably 0.05 to about 0.5 weight percent, based on the
total weight of the formulated oil or lubricating engine oil.
Antioxidants
[0137] 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.
[0138] 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 propionic 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).
[0139] Effective amounts of one or more catalytic antioxidants may
also be used. The catalytic antioxidants comprise an effective
amount of a) one or more oil soluble polymetal organic compounds;
and, effective amounts of b) one or more substituted
N,N'-diaryl-o-phenylenediamine compounds or c) one or more hindered
phenol compounds; or a combination of both b) and c). Catalytic
antioxidants are more fully described in U.S. Pat. No. 8,048,833,
herein incorporated by reference in its entirety.
[0140] 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.
[0141] 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.
[0142] Sulfurized alkyl phenols and alkali or alkaline earth metal
salts thereof also are useful antioxidants.
[0143] 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 2 weight
percent, more preferably zero to about 1.5 weight percent, more
preferably zero to less than 1 weight percent.
Pour Point Depressants (PPDs)
[0144] 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 about 0.01 to 5 weight percent, preferably
about 0.01 to 1.5 weight percent.
Seal Compatibility Agents
[0145] 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, alkoxysulfolanes, aromatic esters,
aromatic hydrocarbons, esters (butylbenzyl phthalate, for example),
and polybutenyl succinic anhydride. Such additives may be used in
an amount of about 0.01 to 3 weight percent, preferably about 0.01
to 2 weight percent.
Antifoam Agents
[0146] 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.
Inhibitors and Antirust Additives
[0147] Antirust additives (or corrosion inhibitors) are additives
that protect lubricated metal surfaces against chemical attack by
water or other contaminants. A wide variety of these are
commercially available.
[0148] One type of antirust additive is a polar compound that wets
the metal surface preferentially, protecting it with a film of oil.
Another type of antirust additive absorbs water by incorporating it
in a water-in-oil emulsion so that only the oil touches the metal
surface. Yet another type of antirust additive chemically adheres
to the metal to produce a non-reactive surface. Examples of
suitable additives include zinc dithiophosphates, metal phenolates,
basic metal sulfonates, fatty acids and amines. Such additives may
be used in an amount of about 0.01 to 5 weight percent, preferably
about 0.01 to 1.5 weight percent.
Friction Modifiers
[0149] 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.
[0150] Illustrative friction modifiers may include, for example,
organometallic compounds or materials, or mixtures thereof.
Illustrative organometallic friction modifiers useful in the
lubricating engine oil formulations of this disclosure include, for
example, molybdenum amine, molybdenum diamine, an
organotungstenate, a molybdenum dithiocarbamate, molybdenum
dithiophosphates, molybdenum amine complexes, molybdenum
carboxylates, and the like, and mixtures thereof. Similar tungsten
based compounds may be preferable.
[0151] Other illustrative friction modifiers useful in the
lubricating engine oil formulations of this disclosure include, for
example, alkoxylated fatty acid esters, alkanolamides, polyol fatty
acid esters, borated glycerol fatty acid esters, fatty alcohol
ethers, and mixtures thereof.
[0152] Illustrative alkoxylated fatty acid esters include, for
example, polyoxyethylene stearate, fatty acid polyglycol ester, and
the like. These can include polyoxypropylene stearate,
polyoxybutylene stearate, polyoxyethylene isosterate,
polyoxypropylene isostearate, polyoxyethylene palmitate, and the
like.
[0153] Illustrative alkanolamides include, for example, lauric acid
diethylalkanolamide, palmic acid diethylalkanolamide, and the like.
These can include oleic acid diethyalkanolamide, stearic acid
diethylalkanolamide, oleic acid diethylalkanolamide,
polyethoxylated hydrocarbylamides, polypropoxylated
hydrocarbylamides, and the like.
[0154] Illustrative polyol fatty acid esters include, for example,
glycerol mono-oleate, saturated mono-, di-, and tri-glyceride
esters, glycerol mono-stearate, and the like. These can include
polyol esters, hydroxyl-containing polyol esters, and the like.
[0155] Illustrative borated glycerol fatty acid esters include, for
example, borated glycerol mono-oleate, borated saturated mono-,
di-, and tri-glyceride esters, borated glycerol mono-sterate, and
the like. In addition to glycerol polyols, these can include
trimethylolpropane, pentaerythritol, sorbitan, and the like. These
esters can be polyol monocarboxylate esters, polyol dicarboxylate
esters, and on occasion polyoltricarboxylate esters. Preferred can
be the glycerol mono-oleates, glycerol dioleates, glycerol
trioleates, glycerol monostearates, glycerol distearates, and
glycerol tristearates and the corresponding glycerol
monopalmitates, glycerol dipalmitates, and glycerol tripalmitates,
and the respective isostearates, linoleates, and the like. On
occasion the glycerol esters can be preferred as well as mixtures
containing any of these. Ethoxylated, propoxylated, butoxylated
fatty acid esters of polyols, especially using glycerol as
underlying polyol can be preferred.
[0156] Illustrative fatty alcohol ethers include, for example,
stearyl ether, myristyl ether, and the like. Alcohols, including
those that have carbon numbers from C.sub.3 to C.sub.50, can be
ethoxylated, propoxylated, or butoxylated to form the corresponding
fatty alkyl ethers. The underlying alcohol portion can preferably
be stearyl, myristyl, C.sub.11-C.sub.13 hydrocarbon, oleyl,
isosteryl, and the like.
[0157] Useful concentrations of friction modifiers may range from
0.01 weight percent to 5 weight percent, or about 0.1 weight
percent to about 2.5 weight percent, or about 0.1 weight percent to
about 1.5 weight percent, or about 0.1 weight percent to about 1
weight percent. Concentrations of molybdenum-containing materials
are often described in terms of Mo metal concentration.
Advantageous concentrations of Mo may range from 25 ppm to 700 ppm
or more, and often with a preferred range of 50-200 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.
[0158] 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.
[0159] 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 diluents.
Accordingly, the weight amounts in the table below, as well as
other amounts mentioned herein, 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-00003 TABLE 2 Typical Amounts of Other Lubricating Oil
Components Approximate Approximate wt % wt % Compound (Useful)
(Preferred) Dispersant 0.1-20 0.1-8 Detergent 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 0.1-2 0.1-1 (solid polymer basis) Antiwear
0.1-2 0.5-1 Inhibitor and Antirust 0.01-5 0.01-1.5
[0160] 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.
[0161] Formulated engine oils of the instant disclosure exhibit
substantial elimination of LSPI. Substantial elimination of LSPI
means greater than about 95%, or greater than about 97%, or greater
than about 99% reduced low speed pre-ignition, based on normalized
low speed pre-ignition (LSPI) counts per 25,000 engine cycles,
engine operation at 2000 revolutions per minute (RPM) and brake
mean effective pressure (BMEP) at 18 bar.
[0162] Formulated engine oils with higher ash levels of 1.2 to 1.6%
or more in conjunction with the other components disclosed in this
disclosure can significantly reduce the number of LSPI events by
96% or more. Formulated engine oils with lower ash levels of 0.2 to
1.2% in conjunction with the other components disclosed in this
disclosure can reduce the number of LSPI events entirely.
[0163] Engines that are highly susceptible to Low speed
pre-ignition (LSPI) are those which operate at high brake mean
effective pressure (BMEP) and low engine speed (RPM). This includes
internal combustion engines using a variety of fuels, including
natural gas, gasoline, diesel, biofuels, and the like. Downsized,
downspeeded, forced-induction (eg. Turbocharged) engines are most
susceptible to operating under these engine conditions and are thus
more susceptible to LSPI. Non-limiting examples of engines
possessing these characteristics include the GM Ecotec and Ford
EcoBoost family of engines as well as other high BMEP (capable of
>10 bar) engines with displacements ranging from about 1 L to
about 6 L as well as engines possessing between 2-10 combustion
cylinders in geometric configurations including inline, flat
(Boxer), and "V" (eg "V8", "in-line 3", "in-line 4", "flat 4"
etc.). Furthermore the calibration and operational setpoints of the
engine may significantly influence both the frequency and severity
of LSPI events.
[0164] The following non-limiting examples are provided to
illustrate the disclosure.
EXAMPLES
Example A
[0165] Formulations were prepared as described in FIG. 1. All of
the ingredients used herein are commercially available. Group III,
IV and V base stocks were used in the formulations.
[0166] The antiwear agents used in the formulations were ZDDP
derived from a secondary alcohol (which contained 10% by weight
Phosphorus and was prepared from mixed C3 and C6 secondary
alcohols) and ZDDP derived from a primary alcohol (which contained
7% by weight Phosphorus and was prepared from C8 primary alcohols).
In addition, zinc only and phosphorus only antiwear additives were
used in the formulations.
[0167] The remaining ingredients used in the formulations were one
or more of a viscosity index improver, antioxidant, dispersant,
antiwear agent, pour point depressant, corrosion inhibitor, metal
deactivator, seal compatibility additive, anti-foam agent,
inhibitor, anti-rust additive, and friction modifier.
[0168] Testing was conducted for formulations described in FIG. 1.
The results are set forth in FIG. 1. Sulfated ash testing was
determined in accordance with ASTM D874. Zinc and phosphorus
content were determined in accordance with ASTM D6443.
[0169] It has been documented that different engine hardware and
control schemes can significantly influence the occurrence of LSPI.
See, for example, U.S. Patent Application Publication Nos.
2012/1866225 and 2003/0908070, and also SAE 2012-02-1148, SAE
2011-01-0340, and SAE 2011-01-0343, which are all incorporated
herein by reference. Furthermore, FIG. 12 shows drive cycle data
obtained from a taxi cab field trial. Two different 2.0L L4 TGDI
engine types, from different Original Equipment Manufacturers were
driven in a typical taxi cab city drive cycle for 2 weeks. Engine
performance data was collected using the vehicles' OBD-II data
ports and mapped onto the published engine torque maps for the
respective engines. As published in SAE 2011-01-0339, engines are
specifically prone to LSPI when they operate in a region above 10
bar BMEP and below 3000 rpm engine speed. Therefore, any region of
the torque maps for these engines which is bounded by these
operating conditions is potentially prone to LSPI. Based on the
measured data for the OBD-II data loggers, it can be shown that
engines with different calibrations can exhibit different LSPI
behavior based on how they are tuned. FIG. 12 shows approximately
1.2 million data points summarizing the operation of two different
engine types in a typical taxi cab city driving cycle over a 2 week
period. Several taxi cabs using each engine type were observed in
this manner. Engine Make 1 spends on average 1.67% of its operating
time in the LSPI "danger zone" while Engine Make 2 only spends on
average 0.17% in a typical taxi cab city drive cycle, even though
both engines are 2.0 L inline 4-cylinder TGDI engines. Furthermore,
Engine Make 2 has exhibited zero LSPI related field failures, while
Engine Make 1 has exhibited multiple failures related to LSPI. This
further illustrates the different responsiveness of different
engine platforms to LSPI.
[0170] For the purposes of this disclosure, a 2.0 L, 4-cylinder
TGDI GM Ecotec engine was used for LSPI testing. A six segment test
procedure was used to determine the number of LSPI events that
occurred at two different specified engine load and speed
conditions. Each segment of the test procedure comprised 25,000
engine cycles, where one cycle corresponds to 720 degrees of crank
shaft rotation. The first set of conditions was 2000 RPM and 18 bar
BMEP, hereafter referred to as "High Load". The second set of
conditions was 1500 RPM and 12.5 bar BMEP, hereafter referred to as
"Low Load". The test procedure comprised two segments of High Load,
followed by two segments of Low Load, followed by two segments of
High Load. A 30 minute warm up at 2000 RPM and 4 bar BMEP was also
conducted prior to commencing the test procedure. This test
procedure was repeated four times for each of the lubricants
tested. LSPI events were counted during the High Load segments
only, using pressure transducers placed in each of the 4 cylinders
to monitor the peak cylinder pressure. Peak pressures in the
cylinder that were greater than 4.7 standard deviations above the
mean peak cylinder pressure, or more than 4.7 standard deviations
below the mean peak cylinder pressure were counted as an LSPI
event. The results of such LSPI testing are set forth in FIG.
1.
[0171] The testing evaluated the impact of ZDDP on LSPI. As shown
in FIG. 1, the use of secondary alcohol derived ZDDP is more
preferable than the use of primary alcohol derived ZDDP, to reduce
LSPI count. Example 1 shows that a secondary ZDDP can be used to
obtain approximately 27 LSPI events, while Comparative Example 1,
at an equivalent zinc and phosphorus content, shows that a primary
ZDDP has unexpectedly higher LSPI counts at 34 counts per 25,000
engine cycles. Thus, the formulation with a secondary alcohol
derived ZDDP exhibits an unexpected reduction in LSPI of 20%. This
novel finding to reduce the LSPI count by the use of secondary
ZDDP, or mostly secondary ZDDP, can be very beneficial to lubricant
formulations. Example 2 presents a case where the ZDDP treat rate
is taken to a very high level and shows that by increasing the
amount of ZDDP within the formulation, the LSPI counts can be
reduced, almost eliminated. Finally Comparative Examples 2 and 3
look further into the benefits of ZDDP by examining the impact of
zinc and phosphorus separately. Comparative Example 2 uses a zinc
only antiwear agent, at an equivalent treat rate to Example 1 and
Comparative Example 1, to yield 36 LSPI counts. Comparative Example
3 on the other hand uses a phosphorus only antiwear agent, at an
equivalent treat rate to Example 1 and Comparative Example 1, to
yield 55 LSPI events. Comparing Comparative Example 2 with
Comparative Example 3, the unique benefits of the zinc compound in
controlling LSPI counts are clearly seen. At the same time, the
detrimental effects of using a phosphorus only antiwear agent can
also be seen.
Example B
[0172] Formulations were prepared as described in FIG. 2. All of
the ingredients used herein are commercially available. Group III,
IV and V base stocks were used in the formulations.
[0173] The antiwear agents used in the formulations were ZDDP
derived from a secondary alcohol and ZDDP derived from a primary
alcohol.
[0174] The dispersants used in the formulations were a borated
succinimide (which comprised a borated polyisobutenyl succinimede
with a B/N ratio equal to about 0.5), a high molecular weight
succinimide (High MW Succinimide Dispersant 1 which comprised an
ethylene carbonate-capped bis-polyisobutenyl succinimide dispersant
with about 1% total nitrogen) and a high molecular weight
succinimide (High MW Succinimide Dispersant 2 which comprised a
bis-polyisobutenyl succinimde with about 1.2% total nitrogen).
[0175] The remaining ingredients used in the formulations were one
or more of a viscosity index improver, antioxidant, dispersant,
antiwear agent, pour point depressant, corrosion inhibitor, metal
deactivator, seal compatibility additive, anti-foam agent,
inhibitor, anti-rust additive, and friction modifier.
[0176] Testing was conducted for formulations described in FIG. 2.
The results are set forth in FIG. 3. Sulfated ash testing was
determined in accordance with ASTM D874. Boron, zinc and phosphorus
content were determined in accordance with ASTM D6443. Nitrogen
content was determined in accordance with ASTM D3228. LSPI testing
was conducted for formulations in accordance with the procedures
described in Example 1 using the 2.0 L, 4-cylinder TGDI GM Ecotec
engine.
[0177] The testing evaluated the impact of borated dispersants and
ZDDP derived from secondary alcohols on LSPI. As shown in FIG. 3,
the use of a borated dispersant and secondary ZDDP is unexpectedly
beneficial to LSPI performance. Example 1, Comparative Example 4,
Comparative Example 5, and Example 3 all use secondary ZDDP
antiwear agent at the same treat rate while the dispersant is being
varied. As indicated by the boron content in these blends, as the
boron content increases, the LSPI count unexpectedly reduces.
Specifically, Example 3 which has about 507 ppm of boron has only
24 LSPI events, while Comparative Examples 4 and 5 which have no
boron present, have 46 and 43 LSPI events, respectively. Going from
no boron, to 240 ppm boron, to 507 ppm boron, reduces LSPI count
from 46, to 27, to 24, respectively. That is a 40% LSPI reduction
with 240 ppm of boron and a 48% LSPI reduction with about 507 ppm
of boron. The LSPI reduction is expected to continue as the boron
level is increased. The benefits of using a borated dispersant with
a secondary ZDDP are clearly seen. Comparative Example 1 further
demonstrates the unique and unexpected benefits of a borated
dispersant and a secondary ZDDP by showing the disadvantages of a
borated dispersant and a primary ZDDP. When compared with Example
1, which has the same level of boron as Comparative Example 1,
Comparative Example 1 shows an increase in LSPI count from 27 to 34
when the secondary ZDDP is switched out for a primary ZDDP.
[0178] Comparative Example 8 shows an example in which no
dispersants are used, and had an LSPI count of 22. While this is
virtually the same as the blends which contained a boarated
disperant, this further demonstrates the utility of borated
dispersants for reducing LSPI for oils used in commercial
applications. Typically dispersants are required to be used to
disperse sludge and other particulate matter which may be generated
during normal operation. Comparing Comparative Example 4 with
Comparative Example 4 shows that non-borated disperants can cause
an increase in LSPI by almost 100%, while using borated dispersant
alone or in combination with other non-borated dispersants reduces
LSPI frequency.
Example C
[0179] Formulations were prepared as described in FIG. 4. All of
the ingredients used herein are commercially available. Group III,
IV and V base stocks were used in the formulations.
[0180] The detergents used in the formulations were a medium TBN
calcium alkyl salicylate (Calcium Salicylate 1 which contains 7.3%
Ca and has a TBN of about 200), a low TBN calcium alkyl salicylate
(Calcium Salicylate 2 which contains 2.3% Ca and about 65 TBN), a
high TBN calcium alkyl sulfonate (Calcium Sulfonate 1 which
contains 11.6% Ca and about 300 TBN), a low TBN calcium alkyl
sulfonate (Calcium Sulfonate 2 which contains 2.0% Ca and about 8
TBN), and a high TBN magnesium alkyl sulfonate (Magnesium Sulfonate
1 which contains 9.1% Mg and about 400 TBN). The TBN ranges are
defined as: low TBN of about 0 to 100, medium TBN of about 100 to
200, and high TBN of about 200 to as high as 600.
[0181] The dispersants used in the formulations were a borated
succinimide and a high molecular weight succinimide.
[0182] The antiwear agents used in the formulations were ZDDP
derived from a secondary alcohol and ZDDP derived from a primary
alcohol.
[0183] The remaining ingredients used in the formulations were one
or more of a viscosity index improver, antioxidant, dispersant,
antiwear agent, pour point depressant, corrosion inhibitor, metal
deactivator, seal compatibility additive, anti-foam agent,
inhibitor, anti-rust additive, and friction modifier.
[0184] Testing was conducted for formulations described in FIG. 4.
The results are set forth in FIG. 5. Sulfated ash testing was
determined in accordance with ASTM D874. Calcium, magnesium, boron,
zinc and phosphorus content were determined in accordance with ASTM
D6443. Nitrogen content was determined in accordance with ASTM
D3228. LSPI testing was conducted for formulations in accordance
with the procedures described in Example 1 using the 2.0 L,
4-cylinder TGDI GM Ecotec engine.
[0185] The testing evaluated the impact of a three additive system
(i.e., detergent, dispersant and antiwear agent) on LSPI. As shown
in FIG. 5, where LSPI is measured for formulations containing a
non-borated dispersant and for formulations containing a mixture of
non-borated dispersant and borated dispersant, the use of a borated
succinimide dispersant has unique LSPI benefits over high molecular
weight succinimide dispersant. Comparative Example 6, Example 4 and
Example 8 show the impact of increasing boron content on LSPI
performance. As the boron content increases from 0, to 240, to 507
ppm, the LSPI count decreases from 46, to 27, to 24. The benefit of
boron in reducing LSPI frequency represents a significant and
unexpected finding presented in FIGS. 4 and 5. Example 6 and
Example 7 showcase the unique combination of a magnesium sulfonate
detergent with a dual dispersant system and a secondary alcohol
derived ZDDP. The dual dispersant system contains a boron source.
The uniqueness of this combination is shown by comparing to
Comparative Example 6, which uses a different calcium salicylate
based detergent system and has the worst LSPI counts. The use of
magnesium sulfonate detergent, with a secondary alcohol derived
ZDDP, and a borated dispersant is shown to unexpectedly and
significantly reduce, if not eliminate, LSPI. The desirable ratio
of the total concentration of
([Mg]+[Ca]+[Zn]+[P])/([B]+[N].sub.dispersant) is about 2.5 to 7,
more preferably from about 3.3 to 5. Comparing Example 4 with
Example 10 further demonstrates the utility of this approach
incorporating a borated dispersant with a secondary alcohol derived
ZDDP and a combination of a magnesium sulfonate detergent with a
calcium salicylate detergent. Example 10 shows a reduction in LSPI
by 98% compared to Comparative Example 6.
Example D
[0186] The lubricating engine oil formulations in FIGS. 6 and 7 are
combinations of additives and base stocks and are anticipated to
have kinematic viscosity at 100.degree. C. around 7.5-8.5 cSt and
high temperature high shear (10.sup.-6 s.sup.-1) viscosity at
150.degree. C. around 2.5 to 2.9 cP. The lubricating engine oil
formulations of Examples P1, P2, P3 are expected to have boron to
dispersant nitrogen ratios of 0.05, 0.15, and 0.51, respectively.
The total boron content in these formulations is expected to range
from 50 ppm to 800 ppm. The ([Mg]+[Ca])/([B]+[N].sub.dispersant)
ratio is expected to range from 1.28 for Example P3 to 2.91 for
Example P1. Similarly, the ([Zn]+[P])/([B]+[N].sub.dispersant)
ratio is expected to range from 0.71 for Example P3 and 1.62 for
Example P1. Finally, the
([Mg]+[Ca]+[Zn]+[P])/([B]+[N].sub.dispersant) ratio of Examples P1,
P2 and P3, is expected to be between 1.99 and 4.53. The lubricating
engine oil formulations of Examples P4 and P5 are expected to have
magnesium content of 300 ppm to 600 ppm. Similarly the lubricating
engine oil formulations of Examples P6, P7, and P8 are expected to
have magnesium content of about 300 ppm to 900 ppm and a magnesium
to calcium ratio of about 0.12 for Example P6 to 1.21 for Example
P8. At the same time, the TBN of these examples is varying from 6.8
for Examples P8, to P9 for Example P6. Similarly the sulfated ash
content in Example P4, P5, and P6 is varying from 0.3 wt % to 1.2
wt % ash. The other ratios identified in FIGS. 6 and 7 are also
changing as indicated therein. The lubricating engine oil
formulations of Examples P9 and P10 are expected to have magnesium
to calcium ratio of about 0.06 and 3, respectively, at a constant
TBN. The lubricating engine oil formulations of Examples P11, P12
and P13 are expected to have zinc content ranging from about 96 ppm
for Example P13 to about 635 ppm for Example P11. The lubricating
engine oil formulations of Examples P11, P12 and P13 are expected
to have phosphorus content ranging from about 87 ppm for Example
P13 to about 570 ppm for Example P11. The ([Mg]+[Ca])/([Zn]+[P])
ratio ranges from about 2.5 for Example P11 to 16.5 for Example
P13. The ([Zn]+[P])/([B]+[N].sub.dispersant) ratio ranges from
about 1 for Example P11 to 0.15 for Example P13. The
([Mg]+[Ca]+[Zn]+[P])/([B]+[N].sub.dispersant) ratio ranges from
about 3.4 for c Example P11 to 2.6 for c Example P13.
Example E
[0187] The lubricating engine oil formulations in FIGS. 8 and 9 are
combinations of additives and base stocks and are anticipated to
have kinematic viscosity at 100.degree. C. around 5.5-7.5 cSt and
high temperature high shear (10.sup.-6 s.sup.-1) viscosity at
150.degree. C. around 2 to 2.5 cP. The lubricating engine oil
formulations of Examples P14, P15 and P16 are expected to have
boron to dispersant nitrogen ratios of 0.05, 0.15, and 0.51,
respectively. The total boron content in these formulations is
expected to range from 50 ppm to 800 ppm. The
([Mg]+[Ca])/([B]+[N].sub.dispersant) ratio is expected to range
from 1.28 for Example P16 to 2.91 for Example P14. Similarly, the
([Zn]+[P])/([B]+[N].sub.dispersant) ratio is expected to range from
0.71 for Example P16 and 1.62 for Example P14. Finally, the
([Mg]+[Ca]+[Zn]+[P])/([B]+[N].sub.dispersant) ratio of Examples
P14, P15 and P16, is expected to be between 1.99 and 4.53. The
lubricating engine oil formulations of Examples P17 and P18 are
expected to have magnesium content of 300 ppm to 600 ppm. Similarly
the lubricating engine oil formulations of Examples P19, P20, and
P21 are expected to have magnesium content of about 300 ppm to 900
ppm and a magnesium to calcium ratio of about 0.12 for Example P19
to 1.21 for Example P21. At the same time, the TBN of these
examples is varying from 6.8 for Example P21, to 9 for Example P19.
Similarly the sulfated ash content in Example P17, P18, and P19 is
varying from 0.3 wt % to 1.2 wt % ash. The other ratios identified
in FIGS. 8 and 9 are also changing as indicated therein. The
lubricating engine oil formulations of Examples P22 and P23 are
expected to have magnesium to calcium ratio of about 0.06 and 3,
respectively, at a constant TBN. The lubricating engine oil
formulations of Examples P24, P25, and P26 are expected to have
zinc content ranging from about 96 ppm for Example P26 to about 635
ppm for Example P24. The lubricating engine oil formulations of
Examples P24, P25, and P26 are expected to have phosphorus content
ranging from about 87 ppm for Example P26 to about 570 ppm for
Example P24. The ([Mg]+[Ca])/([Zn]+[P]) ratio ranges from about 2.5
for Example P24 to 16.5 for Example P26. The
([Zn]+[P])/([B]+[N].sub.dispersant) ratio ranges from about 1 for
Example P24 to 0.15 for Example P26. The
([Mg]+[Ca]+[Zn]+[P])/([B]+[N].sub.dispersant) ratio ranges from
about 3.4 for Example P24 to 2.6 for Example P26.
Example F
[0188] The lubricating engine oil formulations in FIGS. 10 and 11
are combinations of additives and base stocks and are anticipated
to have kinematic viscosity at 100.degree. C. around 9-11 cSt and
high temperature high shear (10.sup.-6 s.sup.-1) viscosity at
150.degree. C. around 2.9 to 3.4 cP. The lubricating engine oil
formulations of Examples P27, P28, and P29 are expected to have
boron to dispersant nitrogen ratios of 0.05, 0.15, and 0.51,
respectively. The total boron content in these formulations is
expected to range from 50 ppm to 800 ppm. The
([Mg]+[Ca])/([B]+[N].sub.dispersant) ratio is expected to range
from 1.28 for Example P29 to 2.91 for Example P27. Similarly, the
([Zn]+[P])/([B]+[N].sub.dispersant) ratio is expected to range from
0.71 for Example P29 and 1.62 for Example P27. Finally, the
([Mg]+[Ca]+[Zn]+[P])/([B]+[N].sub.dispersant) ratio of Examples
P27, P28, and P29, is expected to be between 1.99 and 4.53. The
lubricating engine oil formulations of Examples P30 and P31 are
expected to have magnesium content of 300 ppm to 600 ppm. Similarly
the lubricating engine oil formulations of Examples P32, P33, and
P34 are expected to have magnesium content of about 300 ppm to 900
ppm and magnesium to calcium ratio of about 0.12 for Example P32 to
1.21 for Example P34. At the same time, the TBN of these examples
is varying from 6.8 for Example P34, to 9 for Example P32.
Similarly the sulfated ash content in Example P30, P31, P32 is
varying from 0.3 wt % to 1.2 wt % ash. The other ratios identified
in FIGS. 10 and 11 are also changing as indicated therein. The
lubricating engine oil formulations of Examples P35 and P36 are
expected to have magnesium to calcium ratio of about 0.06 and 3,
respectively, at a constant TBN. The lubricating engine oil
formulations of Examples P37, P38, and P39 are expected to have
zinc content ranging from about 96 ppm for Example P39 to about 635
ppm for Example P37. The lubricating engine oil formulations of
Examples P37, P38, and P39 are expected to have phosphorus content
ranging from about 87 ppm for Example P39 to about 570 ppm for
Example P37. The ([Mg]+[Ca])/([Zn]+[P]) ratio ranges from about 2.5
for Example P37 to 16.5 for Example P39. The
([Zn]+[P])/([B]+[N].sub.dispersant) ratio ranges from about 1 for
Example P37 to 0.15 for Example P39. The
([Mg]+[Ca]+[Zn]+[P])/([B]+[N].sub.dispersant) ratio ranges from
about 3.4 for Example P37 to 2.6 for Example P39.
PCT and EP Clauses:
[0189] 1. A method for preventing or reducing low speed
pre-ignition in an engine lubricated with a lubricating oil by
using as the lubricating oil a formulated oil, said formulated oil
having a composition comprising a lubricating oil base stock as a
major component; and at least one zinc-containing compound or at
least one antiwear agent, as a minor component; wherein said at
least one antiwear agent comprises at least one zinc dialkyl
dithiophosphate compound derived from a secondary alcohol; and
wherein the engine exhibits greater than 20% reduced low speed
pre-ignition, based on normalized low speed pre-ignition (LSPI)
counts per 25,000 engine cycles, engine operation at 2000
revolutions per minute (RPM) and brake mean effective pressure
(BMEP) at 18 bar, as compared to low speed pre-ignition performance
achieved in an engine using a lubricating oil that does not
comprise at least one zinc-containing compound or antiwear
agent.
[0190] 2. The method of clause 1 wherein the minor component
further comprises at least one boron-containing compound, wherein
said boron-containing compound comprises at least one borated
dispersant, or a mixture of a boron-containing compound and a
non-borated dispersant.
[0191] 3. The method of clause 1 wherein the minor component
further comprises at least one boron-containing compound and at
least one detergent, wherein said boron-containing compound
comprises at least one borated dispersant, or a mixture of a
boron-containing compound and a non-borated dispersant, and wherein
said detergent comprises at least one alkaline earth metal salt of
an organic acid, and said at least one alkaline earth metal salt of
an organic acid comprises at least one magnesium salt of an organic
acid.
[0192] 4. The method of clauses 1-3 wherein the lubricating oil
base stock comprises a Group I, Group II, Group III, Group IV, or
Group V base oil; wherein the Group V base oil comprises an ester
base oil in a concentration of 2% to 20% and having a kinematic
viscosity at 100.degree. C. of 2 cSt to 8 cSt, and the Group III
base oil comprises a GTL base oil.
[0193] 5. The method of clauses 1-4 wherein the zinc-containing
compound is selected from the group consisting of zinc sulfonate,
zinc acetate, zinc napthenate, zinc alkenyl succinate, zinc acid
phosphate salt, zinc phenate, and zinc salicylate.
[0194] 6. The method of clauses 1-5 wherein the zinc dialkyl
dithiophosphate compound is represented by the formula
Zn[SP(S)(OR.sup.1)(OR.sup.2)].sub.2
wherein R.sup.1 and R.sup.2 are independently primary or secondary
C.sub.1 to C.sub.8 alkyl groups, provided at least one of R.sup.1
and R.sup.2 is a secondary C.sub.1 to C.sub.8 alkyl group.
[0195] 7. The method of clauses 1-6 wherein the zinc dialkyl
dithiophosphate compound is derived from (i) a C.sub.3 to C.sub.8
secondary alcohol, or a mixture thereof; or (ii) a mixture of a
C.sub.1 to C.sub.8 primary alcohol and a C.sub.1 to C.sub.8
secondary alcohol.
[0196] 8. The method of clauses 2-7 wherein the boron-containing
compound or borated dispersant is selected from the group
consisting of a borated succinimide, a borated succinate ester, a
borated succinate ester amide, a borated Mannich base, and mixtures
thereof; and the non-borated dispersant comprises a succinic
anhydride derived succinimide or succinate ester with a coupling
agent, wherein the coupling agent comprises a boron-containing
compound.
[0197] 9. The method of clauses 3-8 wherein the ratio of total zinc
from the zinc-containing compound and antiwear agent plus total
alkaline earth metal from the detergent divided by the total boron
from the boron-containing compound and borated dispersant, in the
lubricating oil, is 9.2 to 45.
[0198] 10. The method of clauses 3-9 wherein the alkaline earth
metal salt of an organic acid is selected from the group consisting
of an alkaline earth metal sulfonate, an alkaline earth metal
carboxylate, an alkaline earth metal phenate, an alkaline earth
metal phosphate, and mixtures thereof.
[0199] 11. The method of clauses 3-10 wherein the detergent
comprises (i) at least one of magnesium sulfonate, magnesium
phenate, and magnesium salicylate, and mixtures thereof, and
optionally at least one of calcium sulfonate, calcium phenate, and
calcium salicylate, and mixtures thereof; (ii) at least one
magnesium salt of an organic acid which is selected from magnesium
sulfonate, magnesium carboxylate, magnesium phenate, magnesium
phosphate, and mixtures thereof; or (iii) magnesium sulfonate, a
mixture of magnesium sulfonate and magnesium salicylate, a mixture
of magnesium sulfonate and magnesium phenate, or a mixture of
magnesium sulfonate and magnesium carboxylate.
[0200] 12. The method of clauses 3-11 wherein (i) magnesium and
alkaline earth metal contributed by the detergent is present in the
lubricating oil in an amount from 500 ppm to 5000 ppm; (ii) total
base number (TBN), as measured by ASTM D2896, contributed by the
detergent ranges from 2 mg KOH/g to 17 mg KOH/g; or (iii) sulfated
ash contributed by the detergent ranges from 0.4 to 1.7 wt %.
[0201] 13. A lubricating engine oil having a composition comprising
a lubricating oil base stock as a major component; and at least one
zinc-containing compound or at least one antiwear agent, as a minor
component; wherein said at least one antiwear agent comprises at
least one zinc dialkyl dithiophosphate compound derived from a
secondary alcohol; and wherein the engine exhibits greater than 20%
reduced low speed pre-ignition, based on normalized low speed
pre-ignition (LSPI) counts per 25,000 engine cycles, engine
operation at 2000 revolutions per minute (RPM) and brake mean
effective pressure (BMEP) at 18 bar, as compared to low speed
pre-ignition performance achieved in an engine using a lubricating
oil that does not comprise at least one zinc-containing compound or
antiwear agent.
[0202] 14. The lubricating engine oil of clause 13 wherein the
minor component further comprises at least one boron-containing
compound, wherein said boron-containing compound comprises at least
one borated dispersant, or a mixture of a boron-containing compound
and a non-borated dispersant.
[0203] 15. The lubricating engine oil of clause 13 wherein the
minor component further comprises at least one boron-containing
compound and at least one detergent, wherein said boron-containing
compound comprises at least one borated dispersant, or a mixture of
a boron-containing compound and a non-borated dispersant, and
wherein said detergent comprises at least one alkaline earth metal
salt of an organic acid, and said at least one alkaline earth metal
salt of an organic acid comprises at least one magnesium salt of an
organic acid.
[0204] 16. A method for preventing or reducing low speed
pre-ignition in an engine lubricated with a lubricating oil by
using as the lubricating oil a formulated engine oil, said
formulated engine oil having a composition comprising a lubricating
oil base stock at from 70 to 85 wt. %; and at least one
zinc-containing compound or at least one antiwear agent, at a
loading to contribute from 400 ppm to about 2000 ppm of phosphorous
to the formulated engine oil; wherein said at least one antiwear
agent comprises at least one zinc dialkyl dithiophosphate compound
derived at least in part from a secondary alcohol; wherein the
engine exhibits greater than 50% reduced low speed pre-ignition,
based on normalized low speed pre-ignition (LSPI) counts per 25,000
engine cycles, engine operation at 2000 revolutions per minute
(RPM) and brake mean effective pressure (BMEP) at 18 bar, as
compared to low speed pre-ignition performance achieved in an
engine using a lubricating oil that does not comprise at least one
zinc-containing compound or at least one antiwear agent.
[0205] All patents and patent applications, test procedures (such
as ASTM methods, UL methods, and the like), and other documents
cited herein are fully incorporated by reference to the extent such
disclosure is not inconsistent with this disclosure and for all
jurisdictions in which such incorporation is permitted.
[0206] When numerical lower limits and numerical upper limits are
listed herein, ranges from any lower limit to any upper limit are
contemplated. While the illustrative embodiments of the disclosure
have been described with particularity, it will be understood that
various other modifications will be apparent to and can be readily
made by those skilled in the art without departing from the spirit
and scope of the disclosure. Accordingly, it is not intended that
the scope of the claims appended hereto be limited to the examples
and descriptions set forth herein but rather that the claims be
construed as encompassing all the features of patentable novelty
which reside in the present disclosure, including all features
which would be treated as equivalents thereof by those skilled in
the art to which the disclosure pertains.
[0207] The present disclosure has been described above with
reference to numerous embodiments and specific examples. Many
variations will suggest themselves to those skilled in this art in
light of the above detailed description. All such obvious
variations are within the full intended scope of the appended
claims.
* * * * *
References