U.S. patent application number 16/029897 was filed with the patent office on 2019-01-31 for method for improving deposit control and cleanliness performance in an engine lubricated with a lubricating oil.
The applicant listed for this patent is ExxonMobil Research and Engineering Company. Invention is credited to Michael L. BLUMENFELD, Smruti A. DANCE, Douglas E. DECKMAN.
Application Number | 20190031975 16/029897 |
Document ID | / |
Family ID | 63036415 |
Filed Date | 2019-01-31 |
View All Diagrams
United States Patent
Application |
20190031975 |
Kind Code |
A1 |
BLUMENFELD; Michael L. ; et
al. |
January 31, 2019 |
METHOD FOR IMPROVING DEPOSIT CONTROL AND CLEANLINESS PERFORMANCE IN
AN ENGINE LUBRICATED WITH A LUBRICATING OIL
Abstract
A method for improving deposit control and cleanliness
performance in an engine lubricated with a lubricating oil by using
as the lubricating oil a formulated oil. The formulated oil
comprises a lubricating oil base stock as a major component, and a
mixture of (i) at least one dispersant, and (ii) at least one
viscosity modifier, as minor components. The at least one
dispersant and the at least one viscosity modifier are present in
an amount sufficient to have a critical dispersant thickening ratio
of greater than 0.33. The critical dispersant thickening ratio is
determined in accordance with the formula: .SIGMA. [ G n ] * dV / d
[ G n ] .SIGMA. [ B m ] * dV / d [ B m ] ##EQU00001## wherein
[G.sub.n] is the weight percent of each of n dispersants in the
formulated oil, [B.sub.m] is the weight percent of each of m
viscosity modifiers in the formulated oil, dV/d[G.sub.n] is the
kinematic viscosity (Kv.sub.100) increase of the lubricating oil
per the weight percent of each of n dispersants in the formulated
oil, and dV/d[B.sub.m] is the kinematic viscosity (Kv.sub.100)
increase of the lubricating oil per the weight percent of each of m
viscosity modifiers in the formulated oil.
Inventors: |
BLUMENFELD; Michael L.;
(Annandale, NJ) ; DANCE; Smruti A.; (Robbinsville,
NJ) ; DECKMAN; Douglas E.; (Easton, PA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
ExxonMobil Research and Engineering Company |
Annandale |
NJ |
US |
|
|
Family ID: |
63036415 |
Appl. No.: |
16/029897 |
Filed: |
July 9, 2018 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
62535433 |
Jul 21, 2017 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10M 2207/123 20130101;
C10M 143/12 20130101; C10N 2030/52 20200501; C10M 143/10 20130101;
C10M 2209/084 20130101; C10M 2205/04 20130101; C10M 2207/282
20130101; C10M 2215/086 20130101; C10N 2030/02 20130101; C10M
2203/1065 20130101; C10M 2205/06 20130101; C10N 2030/45 20200501;
C10M 129/72 20130101; C10M 145/14 20130101; C10M 133/16 20130101;
C10M 169/044 20130101; C10N 2020/073 20200501; C10N 2030/04
20130101; C10M 129/34 20130101; C10N 2040/25 20130101; C10N 2060/14
20130101; C10M 101/02 20130101; C10M 2203/1025 20130101; C10M
161/00 20130101; C10M 2205/0206 20130101; C10M 107/02 20130101 |
International
Class: |
C10M 169/04 20060101
C10M169/04; C10M 129/34 20060101 C10M129/34; C10M 129/72 20060101
C10M129/72; C10M 133/16 20060101 C10M133/16; C10M 145/14 20060101
C10M145/14; C10M 101/02 20060101 C10M101/02; C10M 107/02 20060101
C10M107/02; C10M 143/12 20060101 C10M143/12; C10M 143/10 20060101
C10M143/10 |
Claims
1. A method for improving deposit control and cleanliness
performance in an engine lubricated with a lubricating oil by using
as the lubricating oil a formulated oil, said formulated oil
comprising a lubricating oil base stock as a major component; and a
mixture of (i) at least one dispersant, and (ii) at least one
viscosity modifier, as minor components; wherein the at least one
dispersant and the at least one viscosity modifier are present in
an amount sufficient to have a critical dispersant thickening ratio
of greater than 0.33; wherein the critical dispersant thickening
ratio is determined in accordance with the formula: .SIGMA. [ G n ]
* dV / d [ G n ] .SIGMA. [ B m ] * dV / d [ B m ] ##EQU00009##
wherein [G.sub.n] is the weight percent of each of n dispersants in
the formulated oil, [B.sub.m] is the weight percent of each of m
viscosity modifiers in the formulated oil, dV/d[G.sub.n] is the
kinematic viscosity (Kv.sub.100) increase of the lubricating oil as
determined by ASTM D445 per the weight percent of each of n
dispersants in the formulated oil, and dV/d[B.sub.m] is the
kinematic viscosity (Kv.sub.100) increase of the lubricating oil as
determined by ASTM D445 per the weight percent of each of m
viscosity modifiers in the formulated oil.
2. The method of claim 1 wherein the amount of the at least one
dispersant and the at least one viscosity modifier is sufficient to
provide a critical dispersant thickening ratio of greater than 0.33
in a direct injection, ring sticking (rings 1 and 2), and piston
cleanliness test using a Volkswagen TDI2 test engine, in accordance
with CEC L78-T-99 test procedure.
3. The method of claim 1 wherein the critical dispersant thickening
ratio is greater than 0.47.
4. The method of claim 1 wherein the critical dispersant thickening
ratio is greater than 0.75.
5. The method of claim 1 wherein the critical dispersant thickening
ratio is greater than 1.0.
6. The method of claim 1 wherein the lubricating oil base stock
comprises a Group I base stock, a Group II base stock, a Group III
base stock, a Group IV base stock, a Group V base stock, or
mixtures thereof.
7. The method of claim 1 wherein the at least one dispersant is an
ashless dispersant.
8. The method of claim 1 wherein the at least one dispersant is
selected from the group consisting of hydrocarbyl-substituted
succinic acid derivatives, hydrocarbyl-substituted succinic
anhydride derivatives, succinimides, succinate esters, succinate
ester amides, Mannich base adducts derived from a
hydrocarbyl-substituted phenol condensed with an aldehyde and an
amine, hydrocarbyl-substituted amines, and polymethacrylate or
polyacrylate derivatives.
9. The method of claim 1 wherein the at least one viscosity
modifier is selected from the group consisting of linear or
star-shaped polymers and copolymers of methacrylate, butadiene,
olefins, or alkylated styrenes.
10. The method of claim 1 wherein the lubricating oil further
comprises one or more of an antioxidant, detergent, pour point
depressant, corrosion inhibitor, metal deactivator, seal
compatibility additive, anti-foam agent, inhibitor, and anti-rust
additive.
11. The method of claim 1 wherein the lubricating oil base stock is
present in an amount from 78 weight percent to 98 weight percent,
the dispersant is present in an amount from 0.5 weight percent to
12 weight percent, and the viscosity modifier is present in an
amount from 0.5 weight percent to 10 weight percent, based on the
total weight of the lubricating oil.
12. The method of claim 1 wherein the lubricating oil is a
passenger vehicle engine oil (PVEO) or a commercial vehicle engine
oil (CVEO).
13. A lubricating oil comprising a lubricating oil base stock as a
major component; and a mixture of (i) at least one dispersant, and
(ii) at least one viscosity modifier, as minor components; wherein
the at least one dispersant and the at least one viscosity modifier
are present in an amount sufficient to have a critical dispersant
thickening ratio of greater than 0.33; wherein the critical
dispersant thickening ratio is determined in accordance with the
formula: .SIGMA. [ G n ] * dV / d [ G n ] .SIGMA. [ B m ] * dV / d
[ B m ] ##EQU00010## wherein [G.sub.n] is the weight percent of
each of n dispersants in the formulated oil, [B.sub.m] is the
weight percent of each of m viscosity modifiers in the formulated
oil, dV/d[G.sub.n] is the kinematic viscosity (Kv.sub.100) increase
of the lubricating oil as determined by ASTM D445 per the weight
percent of each of n dispersants in the formulated oil, and
dV/d[B.sub.m] is the kinematic viscosity (Kv.sub.100) increase of
the lubricating oil as determined by ASTM D445 per the weight
percent of each of m viscosity modifiers in the formulated oil.
14. The lubricating oil of claim 13 wherein the amount of the at
least one dispersant and the at least one viscosity modifier is
sufficient to provide a critical dispersant thickening ratio of
greater than 0.33 in a direct injection, ring sticking (rings 1 and
2), and piston cleanliness test using a Volkswagen TDI2 test
engine, in accordance with CEC L78-T-99 test procedure.
15. The lubricating oil of claim 13 wherein the critical dispersant
thickening ratio is greater than 0.47.
16. The lubricating oil of claim 13 wherein the critical dispersant
thickening ratio is greater than 0.75.
17. The lubricating oil of claim 13 wherein the critical dispersant
thickening ratio is greater than 1.0.
18. The lubricating oil of claim 13 wherein the lubricating oil
base stock comprises a Group I base stock, a Group II base stock, a
Group III base stock, a Group IV base stock, a Group V base stock,
or mixtures thereof.
19. The lubricating oil of claim 13 wherein the at least one
dispersant is an ashless dispersant.
20. The lubricating oil of claim 13 wherein the at least one
dispersant is selected from the group consisting of
hydrocarbyl-substituted succinic acid derivatives,
hydrocarbyl-substituted succinic anhydride derivatives,
succinimides, succinate esters, succinate ester amides, Mannich
base adducts derived from a hydrocarbyl-substituted phenol
condensed with an aldehyde and an amine, hydrocarbyl-substituted
amines, and polymethacrylate or polyacrylate derivatives.
21. The lubricating oil of claim 13 wherein the at least one
viscosity modifier is selected from the group consisting of linear
or star-shaped polymers and copolymers of methacrylate, butadiene,
olefins, or alkylated styrenes.
22. The lubricating oil of claim 13 wherein the lubricating oil
further comprises one or more of an antioxidant, detergent, pour
point depressant, corrosion inhibitor, metal deactivator, seal
compatibility additive, anti-foam agent, inhibitor, and anti-rust
additive.
23. The lubricating oil of claim 13 wherein the lubricating oil
base stock is present in an amount from 78 weight percent to 98
weight percent, the dispersant is present in an amount from 0.5
weight percent to 12 weight percent, and the viscosity modifier is
present in an amount from 0.5 weight percent to 10 weight percent,
based on the total weight of the lubricating oil.
24. The lubricating oil of claim 13 wherein the lubricating oil is
a passenger vehicle engine oil (PVEO) or a commercial vehicle
engine oil (CVEO).
25. A method for tuning deposit control and cleanliness performance
in an engine lubricated with a lubricating oil, said method
comprising: using as the lubricating oil a formulated oil, said
formulated oil comprising a lubricating oil base stock as a major
component; and a mixture of (i) at least one dispersant, and (ii)
at least one viscosity modifier, as minor components; and adjusting
the amount of the at least one dispersant and the at least one
viscosity modifier sufficient to provide a determined critical
dispersant thickening ratio; wherein the critical dispersant
thickening ratio is determined in accordance with the formula:
.SIGMA. [ G n ] * dV / d [ G n ] .SIGMA. [ B m ] * dV / d [ B m ]
##EQU00011## wherein [G.sub.n] is the weight percent of each of n
dispersants in the formulated oil, [B.sub.m] is the weight percent
of each of m viscosity modifiers in the formulated oil,
dV/d[G.sub.n] is the kinematic viscosity (Kv.sub.100) increase of
the lubricating oil as determined by ASTM D445 per the weight
percent of each of n dispersants in the formulated oil, and
dV/d[B.sub.m] is the kinematic viscosity (Kv.sub.100) increase of
the lubricating oil as determined by ASTM D445 per the weight
percent of each of m viscosity modifiers in the formulated oil.
26. The method of claim 25 wherein the amount of the at least one
dispersant and the at least one viscosity modifier is adjusted so
as to tune the critical dispersant thickening ratio from a value
less than 0.33 to a value greater than 0.33.
27. The method of claim 25 wherein the amount of the at least one
dispersant and the at least one viscosity modifier is sufficient to
provide a critical dispersant thickening ratio of greater than 0.33
in a direct injection, ring sticking (rings 1 and 2), and piston
cleanliness test using a Volkswagen TDI2 test engine, in accordance
with CEC L78-T-99 test procedure.
28. The method of claim 25 wherein the critical dispersant
thickening ratio is greater than 0.47.
29. The method of claim 25 wherein the critical dispersant
thickening ratio is greater than 0.75.
30. The method of claim 25 wherein the critical dispersant
thickening ratio is greater than 1.0.
31. The method of claim 25 wherein the lubricating oil base stock
comprises a Group I base stock, a Group II base stock, a Group III
base stock, a Group IV base stock, a Group V base stock, or
mixtures thereof.
32. The method of claim 25 wherein the at least one dispersant is
an ashless dispersant.
33. The method of claim 25 wherein the at least one dispersant is
selected from the group consisting of hydrocarbyl-substituted
succinic acid derivatives, hydrocarbyl-substituted succinic
anhydride derivatives, succinimides, succinate esters, succinate
ester amides, Mannich base adducts derived from a
hydrocarbyl-substituted phenol condensed with an aldehyde and an
amine, hydrocarbyl-substituted amines, and polymethacrylate or
polyacrylate derivatives.
34. The method of claim 25 wherein the at least one viscosity
modifier is selected from the group consisting of linear or
star-shaped polymers and copolymers of methacrylate, butadiene,
olefins, or alkylated styrenes.
35. The method of claim 25 wherein the lubricating oil further
comprises one or more of an antioxidant, detergent, pour point
depressant, corrosion inhibitor, metal deactivator, seal
compatibility additive, anti-foam agent, inhibitor, and anti-rust
additive.
36. The method of claim 25 wherein the lubricating oil base stock
is present in an amount from 78 weight percent to 98 weight
percent, the dispersant is present in an amount from 0.5 weight
percent to 12 weight percent, and the viscosity modifier is present
in an amount from 0.5 weight percent to 10 weight percent, based on
the total weight of the lubricating oil.
37. The method of claim 25 wherein the lubricating oil is a
passenger vehicle engine oil (PVEO) or a commercial vehicle engine
oil (CVEO).
38. The lubricating oil of claim 13 having a sulfated ash content
of less than or equal to 1% by mass.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of U.S. Provisional
Application Ser. No. 62/535,433, filed on Jul. 21, 2017, the entire
contents of which are incorporated herein by reference.
FIELD
[0002] This disclosure relates to a method for improving deposit
control and cleanliness performance in an engine lubricated with a
lubricating oil. This disclosure also relates to a lubricating oil
having a lubricating oil base stock as a major component, and a
mixture of (i) at least one dispersant, and (ii) at least one
viscosity modifier, as minor components. This disclosure further
relates to a method for tuning deposit control and cleanliness
performance in an engine lubricated with a lubricating oil, from
poor to excellent deposit control and cleanliness performance.
BACKGROUND
[0003] Lubricating oils for internal combustion engines contain in
addition to at least one base lubricating oil, additives which
enhance the performance of the lubricating oil. A variety of
additives such as detergents, dispersants, friction reducers,
viscosity modifiers, antioxidants, corrosion inhibitors, antiwear
additives, pour point depressants, seal swell additives, and
antifoam agents are used in lubricating oil compositions.
[0004] During engine operation, oil insoluble oxidation byproducts
are produced. Dispersants help keep these byproducts in solution,
thus diminishing their deposit on metal surfaces. Dispersants may
be ashless or ash-forming in nature. So called ashless dispersants
are organic materials that form substantially no ash upon
combustion.
[0005] A known class of dispersants is the alkenylsuccinic
derivatives, typically produced by the reaction of a long chain
substituted alkenyl succinic compound, usually a substituted
succinic anhydride, with a polyhydroxy or polyamino compound. The
long chain 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.
[0006] Viscosity modifiers are also used in lubricating oil
compositions. These additives provide lubricants with high and low
temperature operability, and impart shear stability at elevated
temperatures and acceptable viscosity at low temperatures.
Viscosity modifiers are well known commercially and in the
literature.
[0007] Engine cleanliness is a critical performance attribute of
modern engine lubricants. A well known engine cleanliness test is a
direct injection, ring sticking (rings 1 and 2), and piston
cleanliness test using a Volkswagen TDI2 test engine, in accordance
with CEC L78-T-99 test procedure. This cleanliness test is a
performance defining test which is required for all engine
lubricants carrying ACEA certification.
[0008] Formulations that fail the CEC L78-T-99 test procedure are
typically reformulated in an attempt to find the particular base
oil and additive concentrations needed to pass the CEC L78-T-99
test procedure. This reformulation effort can be quite cumbersome
and complicated.
[0009] It would be desirable to reduce the formulation complexity
needed to find the particular base oil and additive concentrations
required to pass the CEC L78-T-99 test procedure. In particular, it
would be desirable to reduce the formulation complexity needed to
maintain acceptable to strong cleanliness, as determined by the CEC
L78-T-99 test procedure, to a single parameter threshold.
[0010] The present disclosure also provides many additional
advantages, which shall become apparent as described below.
SUMMARY
[0011] This disclosure relates to a method of using a critical
dispersant thickening ratio to improve the deposit controlling
properties and cleanliness performance of engine lubricants. The
critical dispersant thickening ratio is effectively the ratio of
the thickening efficiency contribution of the dispersant to the
thickening efficiency contribution of the viscosity modifier. The
critical dispersant thickening ratio provides a simple method of
determining whether the deposit controlling properties and
cleanliness performance would be considered acceptable. The
critical dispersant thickening ratio can also be used to tune
deposit control and cleanliness performance, and improve
cleanliness in a formulation which fails the CEC L78-T-99 test
procedure.
[0012] In particular, this disclosure relates in part to a method
for improving deposit control and cleanliness performance in an
engine lubricated with a lubricating oil by using as the
lubricating oil a formulated oil. The formulated oil comprises a
lubricating oil base stock as a major component, and a mixture of
(i) at least one dispersant, and (ii) at least one viscosity
modifier, as minor components. The at least one dispersant and the
at least one viscosity modifier are present in an amount sufficient
to have a critical dispersant thickening ratio of greater than
about 0.33. The critical dispersant thickening ratio is determined
in accordance with the formula:
.SIGMA. [ G n ] * dV / d [ G n ] .SIGMA. [ B m ] * dV / d [ B m ]
##EQU00002##
[0013] wherein [Gn] is the weight percent of each of n dispersants
in the formulated oil, [Bm] is the weight percent of each of m
viscosity modifiers in the formulated oil, dV/d[Gn] is the
kinematic viscosity (Kv100) increase of the lubricating oil as
determined by ASTM D445 per the weight percent of each of n
dispersants in the formulated oil, and dV/d[Bm] is the kinematic
viscosity (Kv100) increase of the lubricating oil as determined by
ASTM D445 per the weight percent of each of m viscosity modifiers
in the formulated oil.
[0014] Further, in particular, this disclosure also relates in part
to a lubricating oil comprising a lubricating oil base stock as a
major component, and a mixture of (i) at least one dispersant, and
(ii) at least one viscosity modifier, as minor components. The at
least one dispersant and the at least one viscosity modifier are
present in an amount sufficient to have a critical dispersant
thickening ratio of greater than about 0.33. The critical
dispersant thickening ratio is determined in accordance with the
formula:
.SIGMA. [ G n ] * dV / d [ G n ] .SIGMA. [ B m ] * dV / d [ B m ]
##EQU00003##
[0015] wherein [Gn] is the weight percent of each of n dispersants
in the formulated oil, [Bm] is the weight percent of each of m
viscosity modifiers in the formulated oil, dV/d[Gn] is the
kinematic viscosity (Kv100) increase of the lubricating oil as
determined by ASTM D445 per the weight percent of each of n
dispersants in the formulated oil, and dV/d[Bm] is the kinematic
viscosity (Kv100) increase of the lubricating oil as determined by
ASTM D445 per the weight percent of each of m viscosity modifiers
in the formulated oil.
[0016] Yet further, in particular, this disclosure also relates in
part to a method for tuning deposit control and cleanliness
performance in an engine lubricated with a lubricating oil. The
method comprises using as the lubricating oil a formulated oil, in
which the formulated oil comprises a lubricating oil base stock as
a major component, and a mixture of (i) at least one dispersant,
and (ii) at least one viscosity modifier, as minor components; and
adjusting the amount of the at least one dispersant and the at
least one viscosity modifier sufficient to provide a determined
critical dispersant thickening ratio. The critical dispersant
thickening ratio is determined in accordance with the formula:
.SIGMA. [ G n ] * dV / d [ G n ] .SIGMA. [ B m ] * dV / d [ B m ]
##EQU00004##
[0017] wherein [Gn] is the weight percent of each of n dispersants
in the formulated oil, [Bm] is the weight percent of each of m
viscosity modifiers in the formulated oil, dV/d[Gn] is the
kinematic viscosity (Kv100) increase of the lubricating oil as
determined by ASTM D445 per the weight percent of each of n
dispersants in the formulated oil, and dV/d[Bm] is the kinematic
viscosity (Kv100) increase of the lubricating oil as determined by
ASTM D445 per the weight percent of each of m viscosity modifiers
in the formulated oil.
[0018] In an embodiment, the amount of the at least one dispersant
and the at least one viscosity modifier is sufficient to provide a
critical dispersant thickening ratio of greater than about 0.33 in
a direct injection, ring sticking (rings 1 and 2), and piston
cleanliness test using a Volkswagen TDI2 test engine, in accordance
with CEC L78-T-99 test procedure.
[0019] It has been surprisingly found that a critical dispersant
thickening ratio can be employed to tune a lubricant formulation
from poor to excellent cleanliness performance based solely on the
critical dispersant thickening ratio, regardless of other
additives/chemistry included in the lubricant formulation.
[0020] Also, it has been surprisingly found that reformulation
complexity previously needed to maintain acceptable to strong
cleanliness in an engine lubricated with a lubricating oil, as
determined by the CEC L78-T-99 test procedure, can be reduced to a
single parameter threshold, namely the critical dispersant
thickening ratio.
[0021] Further objects, features and advantages of the present
disclosure will be understood by reference to the following
drawings and detailed description.
BRIEF DESCRIPTION OF THE DRAWINGS
[0022] FIG. 1 graphically shows a plot of an engine cleanliness
test, namely a direct injection, ring sticking (rings 1 and 2), and
piston cleanliness test using a Volkswagen TDI2 test engine, in
accordance with CEC L78-T-99 test procedure (y axis) and critical
dispersant thickening ratios (x axis), in accordance with the
Examples.
[0023] FIG. 2 shows lubricating oil formulations prepared in
accordance with the Examples, and also testing results from the
formulations in accordance with the Examples.
DETAILED DESCRIPTION
[0024] 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.
[0025] In accordance with this disclosure, a method of using a
critical dispersant thickening ratio to improve the deposit
controlling properties and cleanliness performance of engine
lubricants is provided. The critical dispersant thickening ratio is
effectively the ratio of the thickening efficiency contribution of
the dispersant to the thickening efficiency contribution of the
viscosity modifier. The critical dispersant thickening ratio
provides a simple method of determining whether the deposit
controlling properties and cleanliness performance would be
considered acceptable. The critical dispersant thickening ratio can
also be used to tune deposit control and cleanliness performance,
and improve cleanliness in a formulation which fails the CEC
L78-T-99 test procedure.
[0026] Also, in accordance with this disclosure, the critical
dispersant thickening ratio is determined in accordance with the
formula:
.SIGMA. [ G n ] * dV / d [ G n ] .SIGMA. [ B m ] * dV / d [ B m ]
##EQU00005##
[0027] wherein [Gn] is the weight percent of each of n dispersants
in the formulated oil, [Bm] is the weight percent of each of m
viscosity modifiers in the formulated oil, dV/d[Gn] is the
kinematic viscosity (Kv100) increase of the lubricating oil as
determined by ASTM D445 per the weight percent of each of n
dispersants in the formulated oil, and dV/d[Bm] is the kinematic
viscosity (Kv100) increase of the lubricating oil as determined by
ASTM D445 per the weight percent of each of m viscosity modifiers
in the formulated oil.
[0028] Further, in accordance with this disclosure, cleanliness
performance can be assessed by calculating the critical dispersant
thickening ratio. For example, for each dispersant [Gn] in the
formulated oil, multiply [Gn] by dV/d[Gn], and sum overall all n of
these contributions: .SIGMA.[Gn]*dV/d[Gn]. Then, for each viscosity
modifier [Bm] in the formulated oil, multiply [Bm] by dV/d[Bm], and
sum over all m of these contributions: .SIGMA.[Bm]*dV/d[Bm]. Then,
take the critical dispersant thickening ratio of
.SIGMA.[Gn]*dV/d[Gn] over .SIGMA.[Bm]*dV/d[Bm], and add dispersant
and/or remove viscosity modifier from the formulated oil if the
critical dispersant thickening ratio is less than 0.33, and a
superior passing CEC L78-T-99 test result is desired.
[0029] In an embodiment, the amount of the at least one dispersant
and the at least one viscosity modifier is sufficient to provide a
critical dispersant thickening ratio of greater than about 0.33 in
a direct injection, ring sticking (rings 1 and 2), and piston
cleanliness test using a Volkswagen TDI2 test engine, in accordance
with CEC L78-T-99 test procedure.
[0030] In another embodiment, the critical dispersant thickening
ratio is greater than about 0.33, or greater than about 0.40, or
greater than about 0.47, or greater than about 0.50, or greater
than about 0.60, or greater than about 0.70, or greater than about
0.75, or greater than about 0.80, or greater than about 0.90, or
greater than about 1.0.
[0031] In yet another embodiment, the critical dispersant
thickening ratio can be used to improve mid-SAPS (sulfated ash,
phosphorus and sulfur) light duty engine oil performance in a
direct injection, ring sticking (rings 1 and 2), and piston
cleanliness test using a Volkswagen TDI2 test engine, in accordance
with CEC L78-T-99 test procedure.
[0032] Illustrative lubricating oil base stocks useful in this
disclosure include, for example, Group I base stocks, Group II base
stocks, Group III base stocks, Group IV base stocks, Group V base
stocks, or mixtures thereof. Illustrative lubricating oil base
stocks useful in this disclosure are described more fully
hereinbelow.
[0033] Illustrative dispersants useful in this disclosure include,
for example, hydrocarbyl-substituted succinic acid derivatives,
hydrocarbyl-substituted succinic anhydride derivatives,
succinimides, succinate esters, succinate ester amides, Mannich
base adducts derived from a hydrocarbyl-substituted phenol
condensed with an aldehyde and an amine, hydrocarbyl-substituted
amines, polymethacrylate or polyacrylate derivatives, and the like.
Preferably, the dispersant is an ashless dispersant. Illustrative
dispersants useful in this disclosure are described more fully
hereinbelow.
[0034] Illustrative viscosity modifiers useful in this disclosure
include, for example, linear or star-shaped polymers and copolymers
of methacrylate, butadiene, olefins, alkylated styrenes, and the
like. Illustrative viscosity modifiers useful in this disclosure
are described more fully hereinbelow.
[0035] In an embodiment, the lubricating oil can have other
additives, for example, an antioxidant, detergent, pour point
depressant, corrosion inhibitor, metal deactivator, seal
compatibility additive, anti-foam agent, inhibitor, and anti-rust
additive. Illustrative additives useful in this disclosure are
described more fully hereinbelow. In accordance with this
disclosure, the critical dispersant thickening ratio can be
employed to tune a lubricant formulation from poor to excellent
cleanliness performance based solely on the critical dispersant
thickening ratio, regardless of other additives/chemistry included
in the lubricant formulation.
[0036] In another embodiment, the lubricating oil base stock is
present in an amount from about 78 weight percent to about 98
weight percent, the dispersant is present in an amount from about
0.5 weight percent to about 12 weight percent, and the viscosity
modifier is present in an amount from about 0.5 weight percent to
about 10 weight percent, based on the total weight of the
lubricating oil. As described herein, the amount of the dispersant
and the viscosity modifier can be adjusted so as to tune the
critical dispersant thickening ratio to a desired value.
Illustrative concentrations of base oils, dispersants and viscosity
modifiers useful in this disclosure are described more fully
hereinbelow.
[0037] In a preferred embodiment, a method is provided for
improving deposit control and cleanliness performance in an engine
lubricated with a lubricating oil by using as the lubricating oil a
formulated oil. The formulated oil comprises a lubricating oil base
stock as a major component, and a mixture of (i) at least one
dispersant, and (ii) at least one viscosity modifier, as minor
components. The at least one dispersant and the at least one
viscosity modifier are present in an amount sufficient to have a
critical dispersant thickening ratio of greater than about 0.33.
The critical dispersant thickening ratio is determined in
accordance with the formula described hereinabove.
[0038] In another preferred embodiment, a lubricating oil is
provided comprising a lubricating oil base stock as a major
component, and a mixture of (i) at least one dispersant, and (ii)
at least one viscosity modifier, as minor components. The at least
one dispersant and the at least one viscosity modifier are present
in an amount sufficient to have a critical dispersant thickening
ratio of greater than about 0.33. The critical dispersant
thickening ratio is determined in accordance with the formula
described hereinabove.
[0039] The lubricating oils of this disclosure preferably have less
than or equal to 1% ash (by mass), more preferably less than or
equal to 1% sulfated ash (by mass).
[0040] In yet another preferred embodiment, a method is provided
for tuning deposit control and cleanliness performance in an engine
lubricated with a lubricating oil. The method comprises using as
the lubricating oil a formulated oil, said formulated oil
comprising a lubricating oil base stock as a major component, and a
mixture of (i) at least one dispersant, and (ii) at least one
viscosity modifier, as minor components; and adjusting the amount
of the at least one dispersant and the at least one viscosity
modifier sufficient to provide a determined critical dispersant
thickening ratio. The critical dispersant thickening ratio is
determined in accordance with the formula described
hereinabove.
[0041] In particular, the amount of the at least one dispersant and
the at least one viscosity modifier can be adjusted so as to tune
the critical dispersant thickening ratio to a desired value. For
example, the amount of the at least one dispersant and the at least
one viscosity modifier can be adjusted so as to tune the critical
dispersant thickening ratio from a value less than about 0.33
(i.e., low performers as shown in FIG. 1) to a value greater than
about 0.33 (i.e., intermediate and high performers as shown in FIG.
1).
[0042] In an embodiment, the lubricating oil of this disclosure is
a passenger vehicle engine oil (PVEO) or a commercial vehicle
engine oil (CVEO).
[0043] Examples of techniques that can be employed to characterize
the compositions formed by the process described above include, but
are not limited to, analytical gas chromatography, nuclear magnetic
resonance, thermogravimetric analysis (TGA), inductively coupled
plasma mass spectrometry, differential scanning calorimetry (DSC),
volatility and viscosity measurements.
Lubricating Oil Base Stocks
[0044] A wide range of lubricating oils is known in the art.
Lubricating oils that are useful in the present disclosure are both
natural oils and synthetic oils. Natural and synthetic 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 the 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.
[0045] Groups I, II, III, IV and V are broad categories of base oil
stocks 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 generally have a viscosity
index of between about 80 to 120 and contain greater than about
0.03% sulfur and less than about 90% saturates. Group II base
stocks generally 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 stock generally has
a viscosity index greater than about 120 and contains less than or
equal to about 0.03% sulfur and greater than about 90% saturates.
Group IV includes polyalphaolefins (PAO). Group V base stocks
include base stocks not included in Groups I-IV. Table 1 below
summarizes properties of each of these five groups.
TABLE-US-00001 TABLE 1 Definition of API Base Oil Groups I, II,
III, IV and V 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
polyalphao efins (PAO) products Group V All other base oil stocks
not included in Groups I, II, III or IV
[0046] 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 in the present
disclosure. 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.
[0047] Group II and/or Group III hydroprocessed or hydrocracked
base stocks, as well as synthetic oils such as polyalphaolefins,
alkyl aromatics and synthetic esters, i.e. Group IV and Group V
oils are also well known base stock oils.
[0048] Synthetic oils include hydrocarbon oil. Hydrocarbon oils
include oils such as polymerized and interpolymerized olefins
(polybutylenes, polypropylenes, propylene isobutylene copolymers,
ethylene-olefin copolymers, and ethylene-alphaolefin copolymers,
for example). Polyalphaolefin (PAO) oil base stocks are commonly
used synthetic hydrocarbon oil. By way of example, PAOs derived
from C8, C10, C12, C14 olefins or mixtures thereof may be utilized.
See U.S. Pat. Nos. 4,956,122; 4,827,064; and 4,827,073.
[0049] 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,
C2 to about C32 alphaolefins with the C8 to about C16 alphaolefins,
such as 1-octene, 1-decene, 1-dodecene and the like, being
preferred. The preferred polyalphaolefins are poly-1-octene,
poly-1-decene and poly-1-dodecene and mixtures thereof and mixed
olefin-derived polyolefins. However, the dimers of higher olefins
in the range of C12 to C18 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 dimers, trimers and tetramers of the starting
olefins, with minor amounts of the lower and/or higher oligomers,
having a viscosity range of 1.5 cSt to 12 cSt. PAO fluids of
particular use may include 3 cSt, 3.4 cSt, and/or 3.6 cSt and
combinations thereof. Mixtures of PAO fluids having a viscosity
range of 1.5 cSt to approximately 150 cSt or more may be used if
desired. Unless indicated otherwise, all viscosities cited herein
are measured at 100.degree. C.
[0050] 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.
[0051] 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.
[0052] 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 2 cSt
to about 50 cSt, preferably about 2 cSt to about 30 cSt, more
preferably about 3 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.
[0053] The hydrocarbyl aromatics can be used as a 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 biphenyls, 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 C6 up to about C60 with a range of about C8 to about C20
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 100oC of approximately 2 cSt to about 50 cSt are
preferred, with viscosities of approximately 3 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. Alkylated naphthalene and analogues
may also comprise compositions with isomeric distribution of
alkylating groups on the alpha and beta carbon positions of the
ring structure. Distribution of groups on the alpha and beta
positions of a naphthalene ring may range from 100:1 to 1:100, more
often 50:1 to 1:50 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.
[0054] 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 AlCl3, BF3, or HF
may be used. In some cases, milder catalysts such as FeCl3 or SnCl4
are preferred. Newer alkylation technology uses zeolites or solid
super acids.
[0055] Esters comprise a useful base stock. Additive solvency and
seal compatibility characteristics may be secured by the use of
esters such as the esters of dibasic acids with monoalkanols and
the polyol esters of monocarboxylic acids. Esters of the former
type include, for example, the esters of dicarboxylic acids such as
phthalic acid, succinic acid, alkyl succinic acid, alkenyl succinic
acid, maleic acid, azelaic acid, suberic acid, sebacic acid,
fumaric acid, adipic acid, linoleic acid dimer, malonic acid, alkyl
malonic acid, alkenyl malonic acid, etc., with a variety of
alcohols such as butyl alcohol, hexyl alcohol, dodecyl alcohol,
2-ethylhexyl alcohol, etc. Specific examples of these types of
esters include dibutyl adipate, di(2-ethylhexyl) sebacate,
di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate,
diisodecyl azelate, dioctyl phthalate, didecyl phthalate, dieicosyl
sebacate, etc.
[0056] 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 C5 to C30
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.
[0057] 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 carbon
atoms. These esters are widely available commercially, for example,
the Mobil P-41 and P-51 esters of ExxonMobil Chemical Company.
[0058] 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.
[0059] 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.
[0060] 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.
[0061] 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.
[0062] 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.
[0063] 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 mm2/s to about 50 mm2/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).
[0064] In addition, the GTL base stock(s) and/or base oil(s) are
typically highly paraffinic (>90% saturates), and may contain
mixtures of monocycloparaffins and multicycloparaffins in
combination with non-cyclic isoparaffins. The ratio of the
naphthenic (i.e., cycloparaffin) content in such combinations
varies with the catalyst and temperature used. Further, GTL base
stock(s) and/or base oil(s) typically have very low sulfur and
nitrogen content, generally containing less than 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 phosphorus and aromatics make this
materially especially suitable for the formulation of low SAP
products.
[0065] 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.
[0066] 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).
[0067] Base oils for use in the formulated lubricating oils useful
in the present disclosure are any of the variety of oils
corresponding to API Group I, Group II, Group III, Group IV, and
Group V oils and mixtures thereof, preferably API Group II, Group
III, Group IV, and Group V oils and mixtures thereof, more
preferably the Group III to Group V base oils due to their
exceptional volatility, stability, viscometric and cleanliness
features. Minor quantities of Group I stock, such as the amount
used to dilute additives for blending into formulated lube oil
products, can be tolerated but should be kept to a minimum, i.e.
amounts only associated with their use as diluent/carrier oil for
additives used on an "as-received" basis. Even in regard to the
Group II stocks, it is preferred that the Group II stock be in the
higher quality range associated with that stock, i.e. a Group II
stock having a viscosity index in the range 100<VI<120.
[0068] The base stock component of the present lubricating oils
will typically be from 1 to 99 weight percent of the total
composition (all proportions and percentages set out in this
specification are by weight unless the contrary is stated) and more
preferably in the range of 10 to 99 weight percent, or more
preferably from 15 to 80 percent, or more preferably from 20 to 70
percent, or more preferably from 25 to 60 percent, or more
preferably from 30 to 50 percent.
Dispersants
[0069] During engine operation, oil-insoluble oxidation byproducts
are produced. Dispersants help keep these byproducts in solution,
thus diminishing their deposition on metal surfaces. Dispersants
used in the formulation of the lubricating oil may be ashless or
ash-forming in nature. Preferably, the dispersant is ashless. So
called ashless dispersants are organic materials that form
substantially no ash upon combustion. For example,
non-metal-containing or borated metal-free dispersants are
considered ashless. In contrast, metal-containing detergents form
ash upon combustion.
[0070] 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
or oxygen. Typical hydrocarbon chains contain 50 to 400 carbon
atoms.
[0071] A particularly useful class of dispersants are the
(poly)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.
[0072] 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.
[0073] Succinimides are formed by the condensation reaction between
hydrocarbyl substituted succinic anhydrides and amines. Molar
ratios can vary depending on the polyamine. For example, the molar
ratio of hydrocarbyl substituted succinic anhydride to TEPA can
vary from 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.
[0074] 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.
[0075] 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.
[0076] The molecular weight of the hydrocarbyl substituted succinic
anhydrides used in the preceding paragraphs will typically range
between 800 and 2,500 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.
[0077] 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.
[0078] 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 HNR2 group-containing reactants.
[0079] 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.
[0080] Preferred dispersants include borated and non-borated
succinimides, including those derivatives from mono-succinimides,
bis-succinimides, and/or mixtures of mono- and bis-succinimides,
wherein the hydrocarbyl succinimide is derived from a
hydrocarbylene group such as polyisobutylene having a Mn of from
about 500 to about 5000, or from about 1000 to about 3000, or about
1000 to about 2000, or a mixture of such hydrocarbylene groups,
often with high terminal vinylic groups. Other preferred
dispersants include succinic acid-esters and amides,
alkylphenol-polyamine-coupled Mannich adducts, their capped
derivatives, and other related components.
[0081] Polymethacrylate or polyacrylate derivatives are another
class of dispersants. These dispersants are typically prepared by
reacting a nitrogen containing monomer and a methacrylic or acrylic
acid esters containing 5-25 carbon atoms in the ester group.
Representative examples are shown in U.S. Pat. Nos. 2, 100, 993,
and 6,323,164. Polymethacrylate and polyacrylate dispersants are
normally used as multifunctional viscosity modifiers. The lower
molecular weight versions can be used as lubricant dispersants or
fuel detergents.
[0082] Illustrative preferred dispersants useful in this disclosure
include those derived from polyalkenyl-substituted mono- or
dicarboxylic acid, anhydride or ester, which dispersant has a
polyalkenyl moiety with a number average molecular weight of at
least 900 and from greater than 1.3 to 1.7, preferably from greater
than 1.3 to 1.6, most preferably from greater than 1.3 to 1.5,
functional groups (mono- or dicarboxylic acid producing moieties)
per polyalkenyl moiety (a medium functionality dispersant).
Functionality (F) can be determined according to the following
formula:
F=(SAP.times.Mn)/((112,200.times.A.I.)-(SAP.times.98))
[0083] wherein SAP is the saponification number (i.e., the number
of milligrams of KOH consumed in the complete neutralization of the
acid groups in one gram of the succinic-containing reaction
product, as determined according to ASTM D94); Mn is the number
average molecular weight of the starting olefin polymer; and A.I.
is the percent active ingredient of the succinic-containing
reaction product (the remainder being unreacted olefin polymer,
succinic anhydride and diluent).
[0084] The polyalkenyl moiety of the dispersant may have a number
average molecular weight of at least 900, suitably at least 1500,
preferably between 1800 and 3000, such as between 2000 and 2800,
more preferably from about 2100 to 2500, and most preferably from
about 2200 to about 2400. The molecular weight of a dispersant is
generally expressed in terms of the molecular weight of the
polyalkenyl moiety. This is because the precise molecular weight
range of the dispersant depends on numerous parameters including
the type of polymer used to derive the dispersant, the number of
functional groups, and the type of nucleophilic group employed.
[0085] Polymer molecular weight, specifically Mn, can be determined
by various known techniques. One convenient method is gel
permeation chromatography (GPC), which additionally provides
molecular weight distribution information (see W. W. Yau, J. J.
Kirkland and D. D. Bly, "Modern Size Exclusion Liquid
Chromatography", John Wiley and Sons, New York, 1979). Another
useful method for determining molecular weight, particularly for
lower molecular weight polymers, is vapor pressure osmometry (e.g.,
ASTM D3592).
[0086] The polyalkenyl moiety in a dispersant preferably has a
narrow molecular weight distribution (MWD), also referred to as
polydispersity, as determined by the ratio of weight average
molecular weight (Mw) to number average molecular weight (Mn).
Polymers having a Mw/Mn of less than 2.2, preferably less than 2.0,
are most desirable. Suitable polymers have a polydispersity of from
about 1.5 to 2.1, preferably from about 1.6 to about 1.8.
[0087] Suitable polyalkenes employed in the formation of the
dispersants include homopolymers, interpolymers or lower molecular
weight hydrocarbons. One family of such polymers comprise polymers
of ethylene and/or at least one C3 to C2 alpha-olefin having the
formula H2C=CHR1 wherein R1 is a straight or branched chain alkyl
radical comprising 1 to 26 carbon atoms and wherein the polymer
contains carbon-to-carbon unsaturation, and a high degree of
terminal ethenylidene unsaturation. Preferably, such polymers
comprise interpolymers of ethylene and at least one alpha-olefin of
the above formula, wherein R1 is alkyl of from 1 to 18 carbon
atoms, and more preferably is alkyl of from 1 to 8 carbon atoms,
and more preferably still of from 1 to 2 carbon atoms.
[0088] Another useful class of polymers is polymers prepared by
cationic polymerization of monomers such as isobutene and styrene.
Common polymers from this class include polyisobutenes obtained by
polymerization of a C4 refinery stream having a butene content of
35 to 75% by wt., and an isobutene content of 30 to 60% by wt. A
preferred source of monomer for making poly-n-butenes is petroleum
feedstreams such as Raffinate II. These feedstocks are disclosed in
the art such as in U.S. Pat. No. 4,952,739. A preferred embodiment
utilizes polyisobutylene prepared from a pure isobutylene stream or
a Raffinate I stream to prepare reactive isobutylene polymers with
terminal vinylidene olefins. Polyisobutene polymers that may be
employed are generally based on a polymer chain of from 1500 to
3000.
[0089] The dispersant(s) are preferably non-polymeric (e.g., mono-
or bis-succinimides). Such dispersants can be prepared by
conventional processes such as disclosed in U.S. Patent Application
Publication No. 2008/0020950, the disclosure of which is
incorporated herein by reference.
[0090] The dispersant(s) can be borated by conventional means, as
generally disclosed in U.S. Pat. Nos. 3,087,936, 3,254,025 and
5,430,105.
[0091] Such dispersants may be used in an amount of about 0.01 to
20 weight percent or 0.01 to 10 weight percent, preferably about
0.5 to 8 weight percent, or more preferably 0.5 to 4 weight
percent. Or such dispersants may be used in an amount of about 2 to
12 weight percent, preferably about 4 to 10 weight percent, or more
preferably 6 to 9 weight percent. On an active ingredient basis,
such additives may be used in an amount of about 0.06 to 14 weight
percent, preferably about 0.3 to 6 weight percent. The hydrocarbon
portion of the dispersant atoms can range from C60 to C1000, or
from C70 to C300, or from C70 to C200. These dispersants may
contain both neutral and basic nitrogen, and mixtures of both.
Dispersants can be end-capped by borates and/or cyclic carbonates.
Nitrogen content in the finished oil can vary from about 200 ppm by
weight to about 2000 ppm by weight, preferably from about 200 ppm
by weight to about 1200 ppm by weight. Basic nitrogen can vary from
about 100 ppm by weight to about 1000 ppm by weight, preferably
from about 100 ppm by weight to about 600 ppm by weight.
[0092] 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.
Viscosity Modifiers
[0093] Viscosity modifiers (also known as viscosity index improvers
(VI improvers), and viscosity improvers) can be included in the
lubricant compositions of this disclosure.
[0094] Viscosity modifiers provide lubricants with high and low
temperature operability. These additives impart shear stability at
elevated temperatures and acceptable viscosity at low
temperatures.
[0095] Suitable viscosity modifiers include high molecular weight
hydrocarbons, polyesters and viscosity modifier dispersants that
function as both a viscosity modifier 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.
[0096] Examples of suitable viscosity modifiers are linear or
star-shaped polymers and copolymers of methacrylate, butadiene,
olefins, or alkylated styrenes. Polyisobutylene is a commonly used
viscosity modifier. Another suitable viscosity modifier is
polymethacrylate (copolymers of various chain length alkyl
methacrylates, for example), some formulations of which also serve
as pour point depressants. Other suitable viscosity modifiers
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.
[0097] 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". Hydrogenated polyisoprene
star polymers are commercially available from Infineum
International Limited, e.g., under the trade designation "SV200",
"SV260", "SV270" and "SV600". Hydrogenated diene-styrene block
copolymers are commercially available from Infineum International
Limited, e.g., under the trade designation "SV 150".
[0098] The polymethacrylate or polyacrylate polymers can be linear
polymers which are available from Evnoik Industries under the trade
designation "Viscoplex.RTM." (e.g., Viscoplex 6-954) or star
polymers which are available from Lubrizol Corporation under the
trade designation Asteric.TM. (e.g., Lubrizol 87708 and Lubrizol
87725).
[0099] Illustrative vinyl aromatic-containing polymers useful in
this disclosure may be derived predominantly from vinyl aromatic
hydrocarbon monomer. Illustrative vinyl aromatic-containing
copolymers useful in this disclosure may be represented by the
following general formula:
A-B
[0100] wherein A is a polymeric block derived predominantly from
vinyl aromatic hydrocarbon monomer, and B is a polymeric block
derived predominantly from conjugated diene monomer.
[0101] In an embodiment of this disclosure, the viscosity modifiers
may be used in an amount of less than about 10 weight percent,
preferably less than about 7 weight percent, more preferably less
than about 4 weight percent, and in certain instances, may be used
at less than 2 weight percent, preferably less than about 1 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 modifiers are typically added as
concentrates, in large amounts of diluent oil.
[0102] As used herein, the viscosity modifier concentrations are
given on an "as delivered" basis. Typically, the active polymer is
delivered with a diluent oil. The "as delivered" viscosity modifier
typically contains from 20 weight percent to 75 weight percent of
an active polymer for polymethacrylate or polyacrylate polymers, or
from 8 weight percent to 20 weight percent of an active polymer for
olefin copolymers, hydrogenated polyisoprene star polymers, or
hydrogenated diene-styrene block copolymers, in the "as delivered"
polymer concentrate.
Other Lubricating Oil Additives
[0103] The formulated lubricating oil useful in the present
disclosure may additionally contain one or more of the commonly
used lubricating oil performance additives including but not
limited to detergents, corrosion inhibitors, rust inhibitors, metal
deactivators, antiwear agents and/or extreme pressure additives,
anti-seizure agents, wax modifiers, fluid-loss additives, seal
compatibility agents, other 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.
[0104] All of the additives described below can be used alone or in
combination. The total treat rates for the additives can range from
1 to 30 percent, or more preferably from 2 to 25 percent, or more
preferably from 3 to 20 percent, or more preferably from 4 to 15
percent, or more preferably from 5 to 10 percent. Particularly
preferred compositions have additive levels between 15 and 20
percent.
[0105] The additives useful in this disclosure do not have to be
soluble in the lubricating oils. Insoluble additives in oil can be
dispersed in the lubricating oils of this disclosure.
[0106] 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.
Detergents
[0107] Illustrative detergents useful in this disclosure include,
for example, alkali metal detergents, alkaline earth metal
detergents, or mixtures of one or more alkali metal detergents and
one or more alkaline earth metal detergents. A typical detergent is
an anionic material that contains a long chain hydrophobic portion
of the molecule and a smaller anionic or oleophobic hydrophilic
portion of the molecule. The anionic portion of the detergent is
typically derived from an organic acid such as a sulfur-containing
acid, carboxylic acid (e.g., salicylic acid), phosphorus-containing
acid, phenol, or mixtures thereof. The counterion is typically an
alkaline earth or alkali metal. The detergent can be overbased as
described herein.
[0108] The detergent is preferably a metal salt of an organic or
inorganic acid, a metal salt of a phenol, or mixtures thereof. The
metal is preferably selected from an alkali metal, an alkaline
earth metal, and mixtures thereof. The organic or inorganic acid is
selected from an aliphatic organic or inorganic acid, a
cycloaliphatic organic or inorganic acid, an aromatic organic or
inorganic acid, and mixtures thereof.
[0109] The metal is preferably selected from an alkali metal, an
alkaline earth metal, and mixtures thereof. More preferably, the
metal is selected from calcium (Ca), magnesium (Mg), and mixtures
thereof.
[0110] The organic acid or inorganic acid is preferably selected
from a sulfur-containing acid, a carboxylic acid, a
phosphorus-containing acid, and mixtures thereof.
[0111] Preferably, the metal salt of an organic or inorganic acid
or the metal salt of a phenol comprises calcium phenate, calcium
sulfonate, calcium salicylate, magnesium phenate, magnesium
sulfonate, magnesium salicylate, an overbased detergent, and
mixtures thereof.
[0112] Salts that contain a substantially stochiometric amount of
the metal are described as neutral salts and have a total base
number (TBN, as measured by ASTM D2896) of from 0 to 80. Many
compositions are overbased, containing large amounts of a metal
base that is achieved by reacting an excess of a metal compound (a
metal hydroxide or oxide, for example) 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 calcium
salicylate, sulfonates, phenates and/or magnesium salicylate,
sulfonates, phenates. The TBN ranges can vary from low, medium to
high TBN products, including as low as 0 to as high as 600.
Preferably the TBN delivered by the detergent is between 1 and 20.
More preferably between 1 and 12. 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. 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, can be used. Borated
detergents can also be used.
[0113] Alkaline earth phenates are another useful class of
detergent. These detergents can be made by reacting alkaline earth
metal hydroxide or oxide (CaO, Ca(OH)2, BaO, Ba(OH)2, MgO, Mg(OH)2,
for example) with an alkyl phenol or sulfurized alkylphenol. Useful
alkyl groups include straight chain or branched C1-C30 alkyl
groups, preferably, C4-C20 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.
[0114] In accordance with this disclosure, metal salts of
carboxylic acids are preferred detergents. These carboxylic acid
detergents may be prepared by reacting a basic metal compound with
at least one carboxylic acid and removing free water from the
reaction product. These compounds may be overbased to produce the
desired TBN level. Detergents made from salicylic acid are one
preferred class of detergents derived from carboxylic acids. Useful
salicylates include long chain alkyl salicylates. One useful family
of compositions is of the formula
##STR00001##
[0115] 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 C11, preferably C13
or greater. R may be optionally substituted with substituents that
do not interfere with the detergent's function. M is preferably,
calcium, magnesium, barium, or mixtures thereof. More preferably, M
is calcium.
[0116] Hydrocarbyl-substituted salicylic acids may be prepared from
phenols by the Kolbe reaction (see U.S. Pat. No. 3,595,791). The
metal salts of the hydrocarbyl-substituted salicylic acids may be
prepared by double decomposition of a metal salt in a polar solvent
such as water or alcohol.
[0117] Alkaline earth metal phosphates are also used as detergents
and are known in the art.
[0118] 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.
[0119] Preferred detergents include calcium sulfonates, magnesium
sulfonates, calcium salicylates, magnesium salicylates, calcium
phenates, magnesium phenates, and other related components
(including borated detergents), and mixtures thereof. Preferred
mixtures of detergents include magnesium sulfonate and calcium
salicylate, magnesium sulfonate and calcium sulfonate, magnesium
sulfonate and calcium phenate, calcium phenate and calcium
salicylate, calcium phenate and calcium sulfonate, calcium phenate
and magnesium salicylate, calcium phenate and magnesium phenate.
Overbased detergents are also preferred.
[0120] The detergent concentration in the lubricating oils of this
disclosure can range from about 0.5 to about 6.0 weight percent,
preferably about 0.6 to 5.0 weight percent, and more preferably
from about 0.8 weight percent to about 4.0 weight percent, based on
the total weight of the lubricating oil.
[0121] 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 100 weight percent, or from
about 40 weight percent to about 60 weight percent, of active
detergent in the "as delivered" detergent product.
Antioxidants
[0122] 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.
[0123] 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 C6+ alkyl groups and the alkylene coupled
derivatives of these hindered phenols. Examples of phenolic
materials of this type 2-t-butyl-4-heptyl phenol; 2-t-butyl-4-octyl
phenol; 2-t-butyl-4-dodecyl phenol; 2,6-di-t-butyl-4-heptyl phenol;
2,6-di-t-butyl-4-dodecyl phenol; 2-methyl-6-t-butyl-4-heptyl
phenol; and 2-methyl-6-t-butyl-4-dodecyl phenol. Other useful
hindered mono-phenolic antioxidants may include for example
hindered 2,6-di-alkyl-phenolic proprionic ester derivatives.
Bis-phenolic antioxidants may also be advantageously used in
combination with the instant disclosure. Examples of ortho-coupled
phenols include: 2,2'-bis(4-heptyl-6-t-butyl-phenol);
2,2'-bis(4-octyl-6-t-butyl-phenol); and
2,2'-bis(4-dodecyl-6-t-butyl-phenol). Para-coupled bisphenols
include for example 4,4'-bis(2,6-di-t-butyl phenol) and
4,4'-methylene-bis(2,6-di-t-butyl phenol).
[0124] 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.
[0125] 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 R8R9R10N where R8 is an
aliphatic, aromatic or substituted aromatic group, R9 is an
aromatic or a substituted aromatic group, and R10 is H, alkyl, aryl
or R11S(O)XR12 where R11 is an alkylene, alkenylene, or aralkylene
group, R12 is a higher alkyl group, or an alkenyl, aryl, or alkaryl
group, and x is 0, 1 or 2. The aliphatic group R8 may contain from
1 to about 20 carbon atoms, and preferably contains from about 6 to
12 carbon atoms. The aliphatic group is a saturated aliphatic
group. Preferably, both R8 and R9 are aromatic or substituted
aromatic groups, and the aromatic group may be a fused ring
aromatic group such as naphthyl. Aromatic groups R8 and R9 may be
joined together with other groups such as S.
[0126] Typical aromatic amines antioxidants have alkyl substituent
groups of at least about 6 carbon atoms. Examples of aliphatic
groups include hexyl, heptyl, octyl, nonyl, and decyl. Generally,
the aliphatic groups will not contain more than about 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.
[0127] Sulfurized alkyl phenols and alkali or alkaline earth metal
salts thereof also are useful antioxidants.
[0128] 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 about 0.01 to 5 weight percent, preferably about 0.01 to
1.5 weight percent, more preferably zero to less than 1.5 weight
percent, more preferably zero to less than 1 weight percent.
Pour Point Depressants (PPDs)
[0129] 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.
Antiwear Additives
[0130] A metal alkylthiophosphate and more particularly a metal
dialkyl dithio phosphate in which the metal constituent is zinc, or
zinc dialkyl dithio phosphate (ZDDP) can be a useful component of
the lubricating oils of this disclosure. ZDDP can be derived from
primary alcohols, secondary alcohols or mixtures thereof. ZDDP
compounds generally are of the formula
Zn[SP(S)(OR1)(OR2)]2
[0131] where R1 and R2 are C1-C18 alkyl groups, preferably C2-C12
alkyl groups. These alkyl groups may be straight chain or branched.
Alcohols used in the ZDDP can be propanol, 2-propanol, butanol,
secondary butanol, pentanols, hexanols such as 4-methyl-2-pentanol,
n-hexanol, n-octanol, 2-ethyl hexanol, alkylated phenols, and the
like. Mixtures of secondary alcohols or of primary and secondary
alcohol can be preferred. Alkyl aryl groups may also be used.
[0132] Preferable zinc dithiophosphates which are commercially
available include secondary zinc dithiophosphates such as those
available from for example, The Lubrizol Corporation under the
trade designations "LZ 677A", "LZ 1095" and "LZ 1371", from for
example Chevron Oronite under the trade designation "OLOA 262" and
from for example Afton Chemical under the trade designation "HITEC
7169".
[0133] The ZDDP is typically used in amounts of from about 0.3
weight percent to about 1.5 weight percent, preferably from about
0.4 weight percent to about 1.2 weight percent, more preferably
from about 0.5 weight percent to about 1.0 weight percent, and even
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 secondary ZDDP and present in an amount of from about 0.6 to
1.0 weight percent of the total weight of the lubricating oil.
Seal Compatibility Agents
[0134] Seal compatibility agents help to swell elastomeric seals by
causing a chemical reaction in the fluid or physical change in the
elastomer. Suitable seal compatibility agents for lubricating oils
include organic phosphates, aromatic esters, aromatic hydrocarbons,
esters (butylbenzyl phthalate, for example), and polybutenyl
succinic anhydride. Such additives may be used in an amount of
about 0.01 to 3 weight percent, preferably about 0.01 to 2 weight
percent.
Antifoam Agents
[0135] 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
[0136] 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.
[0137] 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.
[0138] 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
[0139] 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.
[0140] 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.
[0141] 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.
[0142] 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.
[0143] 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.
[0144] 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.
[0145] 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.
[0146] Illustrative fatty alcohol ethers include, for example,
stearyl ether, myristyl ether, and the like. Alcohols, including
those that have carbon numbers from C3 to C50, can be ethoxylated,
propoxylated, or butoxylated to form the corresponding fatty alkyl
ethers. The underlying alcohol portion can preferably be stearyl,
myristyl, C11-C13 hydrocarbon, oleyl, isosteryl, and the like.
[0147] The lubricating oils of this disclosure exhibit desired
properties, e.g., wear control, in the presence or absence of a
friction modifier.
[0148] 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.
[0149] 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 2 below.
[0150] 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. The
weight percent (wt %) indicated in Table 2 below is based on the
total weight of the lubricating oil composition.
TABLE-US-00002 TABLE 2 Typical Amounts of Other Lubricating Oil
Components Approximate Approximate Compound wt % (Useful) wt %
(Preferred) Dispersant 0.1-12 0.1-8 Viscosity Modifier 0.1-10 0.1-1
(solid polymer basis) Detergent 0.1-20 0.1-8 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 Antiwear 0.2-3 0.5-1 Inhibitor and Antirust
0.01-5 0.01-1.5
[0151] 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.
[0152] The following non-limiting examples are provided to
illustrate the disclosure.
EXAMPLES
[0153] Formulations were prepared as described in FIG. 2. All of
the ingredients used herein are commercially available.
[0154] The dispersants used in the formulations were
polyisobutylsuccinimide/polyamine (PIBSA/PAM, PIB 1300 Mn) borated
dispersant having a typical TBN of 26 mgKOH/g, a typical N content
of 1.7%, and a typical B content of 0.87% (Dispersant 1); PIBSA/PAM
(PIB 1300 Mn) borated dispersant having a typical TBN of 30
mgKOH/g, a typical N content of 1.57%, and a typical B content of
0.77% (Dispersant 2); PIBSA/PAM borated dispersant having a typical
N content of 1.19%, and a typical B content of 2.3% (Dispersant 3);
PIBSA/PAM dispersant having a typical N content of 1.43%
(Dispersant 4); polyisobutenyl bis-succinimide (PIB 2300-2500 Mn)
having a typical TBN of 28 mgKOH/g, and a typical N content of 1.2%
(Dispersant 5); and PIBSA/PAM (PIB 2300-2500 Mn) dispersant capped
with ethylene carbonate and having a typical N content of 1%
(Dispersant 6).
[0155] The viscosity modifiers used in the formulations were a
hydrogenated isoprene star viscosity modifier having a Mw of 567 k
as determined by light scattering and a polydispersity index of 1.6
dissolved in a 4 cSt Fischer-Tropsch Group III base stock
(Viscosity Modifier 1); a non-dispersant, styrene-isoprene star
copolymer viscosity index improver having a Mp of about 825 k
(90%), a Mp of about 119 k (10%), and 17% styrene dissolved in a 4
cSt Fischer-Tropsch Group III base stock (Viscosity Modifier 2); a
solid styrene-isoprene block copolymer having a Mw of about 106 k,
a Mn of about 104 k, and 33% styrene dissolved in a mixture of a 4
cSt Group IV base stock and TMP ester (Viscosity Modifier 3); a
non-dispersant, styrene-isoprene star copolymer viscosity index
improver having a Mp of about 825 k (90%), a Mp of about 119 k
(10%), and 17% styrene dissolved in a 4 cSt hydroprocessed Group
III base stock (Viscosity Modifier 4); a hydrogenated isoprene star
viscosity modifier having a Mw of 936 k as determined by light
scattering and a polydispersity index of 1.7 dissolved in a 100N
Group I base stock (Viscosity Modifier 5); a propylene-butylene
polymer (random) having a mole ratio in the polymer of 3:1
propylene:butylene dissolved in a 4.5 cSt Group II base stock
(Viscosity Modifier 6); a hydrogenated isoprene star viscosity
modifier having a Mw of 786 k as determined by light scattering and
a polydispersity index of 1.56 dissolved in a 4 cSt Group III base
stock (Viscosity Modifier 7); and a hydrogenated isoprene star
viscosity modifier having a Mw of 567 k as determined by light
scattering and a polydispersity index of 1.6 dissolved in a 6 cSt
Group IV base stock (Viscosity Modifier 8).
[0156] Base stocks used in the formulations were one or more of a
Group I base stock, a Group II base stock, a Group III base stock,
a Group IV base stock, a Group V base stock, or mixtures
thereof.
[0157] Other additives used in the formulations were one or more of
an antioxidant, overbased detergent, pour point depressant,
corrosion inhibitor, seal compatibility additive, anti-foam agent,
inhibitor, anti-rust additive, and friction modifier (ashless).
[0158] Testing was conducted for formulations including kinematic
viscosity (Kv100) as determined by ASTM D445, mini-rotary
viscometer (MRV) test as determined by ASTM D5293, high temperature
high shear viscosity (HTHS) as determined by ASTM D4683, and ash
content as determined by ASTM D482. The results are set forth in
FIG. 2.
[0159] Further testing was conducted for formulations using an
engine cleanliness test. The engine cleanliness test was a direct
injection, ring sticking (rings 1 and 2), and piston cleanliness
test using a Volkswagen TDI2 test engine, in accordance with CEC
L78-T-99 test procedure. The results are set forth in FIG. 2.
[0160] Cleanliness performance was assessed by calculating the
critical dispersant thickening ratio as follows: (i) for each
dispersant [Gn] in the formulated oil, multiply [Gn] by dV/d[Gn],
and sum overall all n of these contributions: .SIGMA.[Gn]*dV/d[Gn];
(ii) for each viscosity modifier [Bm] in the formulated oil,
multiply [Bm] by dV/d[Bm], and sum over all m of these
contributions: .SIGMA.[Bm]*dV/d[Bm]; (iii) take the critical
dispersant thickening ratio of .SIGMA.[Gn]*dV/d[Gn] over
.SIGMA.[Bm]*dV/d[Bm], and add dispersant and/or remove viscosity
modifier from the formulated oil if the critical dispersant
thickening ratio is less than 0.33, and a superior passing CEC
L78-T-99 test result is desired. The data presented in FIG. 1 shows
that above a critical dispersant thickening ratio of 0.47, a strong
passing result in the VW TDi2 test is assured, while below a
critical dispersant thickening ratio of 0.33, there are cleanliness
concerns for the formulation.
PCT and EP Clauses:
[0161] 1. A method for improving deposit control and cleanliness
performance in an engine lubricated with a lubricating oil by using
as the lubricating oil a formulated oil, said formulated oil
comprising a lubricating oil base stock as a major component; and a
mixture of (i) at least one dispersant, and (ii) at least one
viscosity modifier, as minor components; wherein the at least one
dispersant and the at least one viscosity modifier are present in
an amount sufficient to have a critical dispersant thickening ratio
of greater than 0.33; wherein the critical dispersant thickening
ratio is determined in accordance with the formula:
.SIGMA. [ G n ] * dV / d [ G n ] .SIGMA. [ B m ] * dV / d [ B m ]
##EQU00006##
[0162] wherein [Gn] is the weight percent of each of n dispersants
in the formulated oil, [Bm] is the weight percent of each of m
viscosity modifiers in the formulated oil, dV/d[Gn] is the
kinematic viscosity (Kv100) increase of the lubricating oil as
determined by ASTM D445 per the weight percent of each of n
dispersants in the formulated oil, and dV/d[Bm] is the kinematic
viscosity (Kv100) increase of the lubricating oil as determined by
ASTM D445 per the weight percent of each of m viscosity modifiers
in the formulated oil.
[0163] 2. The method of clause 1 wherein the amount of the at least
one dispersant and the at least one viscosity modifier is
sufficient to provide a critical dispersant thickening ratio of
greater than 0.33 in a direct injection, ring sticking (rings 1 and
2), and piston cleanliness test using a Volkswagen TDI2 test
engine, in accordance with CEC L78-T-99 test procedure.
[0164] 3. The method of clauses 1 and 2 wherein the critical
dispersant thickening ratio is greater than 0.47, or greater than
0.75, or greater than 1.0
[0165] 4. The method of clauses 1-3 wherein the lubricating oil
base stock comprises a Group I base stock, a Group II base stock, a
Group III base stock, a Group IV base stock, a Group V base stock,
or mixtures thereof.
[0166] 5. The method of clauses 1-4 wherein the at least one
dispersant is an ashless dispersant.
[0167] 6. The method of clauses 1-5 wherein the at least one
dispersant is selected from the group consisting of
hydrocarbyl-substituted succinic acid derivatives,
hydrocarbyl-substituted succinic anhydride derivatives,
succinimides, succinate esters, succinate ester amides, Mannich
base adducts derived from a hydrocarbyl-substituted phenol
condensed with an aldehyde and an amine, hydrocarbyl-substituted
amines, and polymethacrylate or polyacrylate derivatives.
[0168] 7. The method of clauses 1-6 wherein the at least one
viscosity modifier is selected from the group consisting of linear
or star-shaped polymers and copolymers of methacrylate, butadiene,
olefins, or alkylated styrenes.
[0169] 8. The method of clauses 1-7 wherein the lubricating oil
further comprises one or more of an antioxidant, detergent, pour
point depressant, corrosion inhibitor, metal deactivator, seal
compatibility additive, anti-foam agent, inhibitor, and anti-rust
additive.
[0170] 9. The method of clauses 1-8 wherein the lubricating oil
base stock is present in an amount from 78 weight percent to 98
weight percent, the dispersant is present in an amount from 0.5
weight percent to 12 weight percent, and the viscosity modifier is
present in an amount from 0.5 weight percent to 10 weight percent,
based on the total weight of the lubricating oil.
[0171] 10. A lubricating oil comprising a lubricating oil base
stock as a major component; and a mixture of (i) at least one
dispersant, and (ii) at least one viscosity modifier, as minor
components; wherein the at least one dispersant and the at least
one viscosity modifier are present in an amount sufficient to have
a critical dispersant thickening ratio of greater than 0.33;
wherein the critical dispersant thickening ratio is determined in
accordance with the formula:
.SIGMA. [ G n ] * dV / d [ G n ] .SIGMA. [ B m ] * dV / d [ B m ]
##EQU00007##
[0172] wherein [Gn] is the weight percent of each of n dispersants
in the formulated oil, [Bm] is the weight percent of each of m
viscosity modifiers in the formulated oil, dV/d[Gn] is the
kinematic viscosity (Kv100) increase of the lubricating oil as
determined by ASTM D445 per the weight percent of each of n
dispersants in the formulated oil, and dV/d[Bm] is the kinematic
viscosity (Kv100) increase of the lubricating oil as determined by
ASTM D445 per the weight percent of each of m viscosity modifiers
in the formulated oil.
[0173] 11. The lubricating oil of clause 10 wherein the amount of
the at least one dispersant and the at least one viscosity modifier
is sufficient to provide a critical dispersant thickening ratio of
greater than 0.33 in a direct injection, ring sticking (rings 1 and
2), and piston cleanliness test using a Volkswagen TDI2 test
engine, in accordance with CEC L78-T-99 test procedure.
[0174] 12. The lubricating oil of clauses 10 and 11 having a
sulfated ash content of less than or equal to 1% by mass.
[0175] 13. A method for tuning deposit control and cleanliness
performance in an engine lubricated with a lubricating oil, said
method comprising:
[0176] using as the lubricating oil a formulated oil, said
formulated oil comprising a lubricating oil base stock as a major
component; and a mixture of (i) at least one dispersant, and (ii)
at least one viscosity modifier, as minor components; and
[0177] adjusting the amount of the at least one dispersant and the
at least one viscosity modifier sufficient to provide a determined
critical dispersant thickening ratio;
[0178] wherein the critical dispersant thickening ratio is
determined in accordance with the formula:
.SIGMA. [ G n ] * dV / d [ G n ] .SIGMA. [ B m ] * dV / d [ B m ]
##EQU00008##
[0179] wherein [Gn] is the weight percent of each of n dispersants
in the formulated oil, [Bm] is the weight percent of each of m
viscosity modifiers in the formulated oil, dV/d[Gn] is the
kinematic viscosity (Kv100) increase of the lubricating oil as
determined by ASTM D445 per the weight percent of each of n
dispersants in the formulated oil, and dV/d[Bm] is the kinematic
viscosity (Kv100) increase of the lubricating oil as determined by
ASTM D445 per the weight percent of each of m viscosity modifiers
in the formulated oil.
[0180] 14. The method of clause 13 wherein the amount of the at
least one dispersant and the at least one viscosity modifier is
adjusted so as to tune the critical dispersant thickening ratio
from a value less than 0.33 to a value greater than 0.33.
[0181] 15. The method of clauses 13 and 14 wherein the amount of
the at least one dispersant and the at least one viscosity modifier
is sufficient to provide a critical dispersant thickening ratio of
greater than 0.33 in a direct injection, ring sticking (rings 1 and
2), and piston cleanliness test using a Volkswagen TDI2 test
engine, in accordance with CEC L78-T-99 test procedure.
[0182] 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.
[0183] 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.
[0184] 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