U.S. patent application number 15/657248 was filed with the patent office on 2019-01-24 for motorcycle lubricant.
This patent application is currently assigned to Infineum International Limited. The applicant listed for this patent is Infineum International Limited. Invention is credited to Pei Yi Lim, Anne Wai-Yu Young.
Application Number | 20190024007 15/657248 |
Document ID | / |
Family ID | 59649625 |
Filed Date | 2019-01-24 |
United States Patent
Application |
20190024007 |
Kind Code |
A1 |
Lim; Pei Yi ; et
al. |
January 24, 2019 |
Motorcycle Lubricant
Abstract
It has been found that the balance between friction reduction in
the engine crankcase and the maintenance of sufficient friction in
the clutch assembly of a 4T motorcycle, where the engine crankcase
and the clutch assembly are lubricating by the same lubricating oil
composition from a common sump, can be achieved by use of a
lubricating oil composition comprising a combination of molybdenum
containing additive and ashless organic friction modifier.
Inventors: |
Lim; Pei Yi; (Singapore,
SG) ; Young; Anne Wai-Yu; (Brooklyn, NY) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Infineum International Limited |
Abingdon |
|
GB |
|
|
Assignee: |
Infineum International
Limited
Abingdon
GB
|
Family ID: |
59649625 |
Appl. No.: |
15/657248 |
Filed: |
July 24, 2017 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C10N 2030/02 20130101;
C10M 2207/262 20130101; C10M 2207/026 20130101; C10N 2010/12
20130101; C10M 2215/08 20130101; C10M 135/18 20130101; C10M
2219/068 20130101; C10N 2030/45 20200501; C10M 2203/1025 20130101;
C10N 2030/52 20200501; C10M 2215/28 20130101; C10N 2040/255
20200501; C10M 2215/086 20130101; C10N 2020/02 20130101; C10M
2205/04 20130101; C10N 2040/044 20200501; C10M 141/12 20130101;
C10M 2207/289 20130101; C10M 2205/06 20130101; C10N 2060/14
20130101; C10M 2215/064 20130101; C10N 2030/06 20130101; C10M
2223/045 20130101; C10M 2207/28 20130101; C10N 2040/25 20130101;
C10M 125/24 20130101 |
International
Class: |
C10M 135/18 20060101
C10M135/18; C10M 125/24 20060101 C10M125/24 |
Claims
1. A motorcycle having a four cycle engine and a transmission
including a clutch assembly, the engine crankcase and the clutch
assembly being lubricated by a lubricating oil composition provided
from a common sump, wherein said lubricating oil composition
comprises a major amount of oil of lubricating viscosity and minor
amounts of (A) an oil soluble molybdenum compound and (B) an
ashless organic friction modifier, wherein the lubricating oil
composition comprises at least 30 ppm and no more than 500 ppm of
molybdenum from the oil-soluble molybdenum compound (A).
2. (canceled)
3. (canceled)
4. (canceled)
5. A motorcycle as claimed in claim 1, wherein the oil-soluble
molybdenum compound consists of either a molybdenum dithiocarbamate
or a molybdenum dithiophosphate or a mixture thereof, as the sole
source of molybdenum atoms in the lubricating oil composition.
6. A motorcycle as claimed in claim 5, wherein the oil-soluble
molybdenum compound consists of a molybdenum dithiocarbamate, as
the sole source of molybdenum atoms in the lubricating oil
composition.
7. A motorcycle as claimed in claim 1, wherein the lubricating oil
composition wherein the ashless organic friction modifier (B)
comprises at least one of (a) a nitrogen-free organic friction
modifier comprising an ester formed by reacting carboxylic acids
and anhydrides with alkanols, (b) an aminic or amine-based friction
modifiers comprising alkoxylated mono- and di-amines, (c) an ester
formed as the reaction product of (i) a tertiary amine of the
formula R.sub.1R.sub.2R.sub.3N wherein R.sub.1, R.sub.2, and
R.sub.3 represent aliphatic hydrocarbyl groups having 1 to 6 carbon
atoms, at least one of R.sub.1, R.sub.2 and R.sub.3 having a
hydroxyl group, with (ii) a saturated or unsaturated fatty acid
having 10 to 30 carbon atoms, or a mixture thereof.
8. A motorcycle as claimed in claim 1, wherein the total amount of
ashless organic friction modifier (B) in the lubricating oil
composition does not exceed 5 mass %, based on the total mass of
the lubricating oil composition.
9. A motorcycle as claimed in claim 7, wherein the total amount of
ashless organic friction modifier (B) in the lubricating oil
composition does not exceed 5 mass %, based on the total mass of
the lubricating oil composition.
10. A motorcycle as claimed in claim 1, wherein the lubricating oil
composition further comprises an ashless dispersant additive.
11. A motorcycle as claimed in claim 10, wherein the ashless
dispersant additive comprises a major amount of an ashless
dispersant made by the thermal process.
12. A motorcycle as claimed in claim 1, wherein the lubricating oil
composition further comprises metal-containing detergent, which
metal containing detergent is an alkali or alkaline earth metal
sulfonate, phenate or salicylate.
13. A motorcycle as claimed in claim 12, wherein the metal
containing detergent comprises an alkali or alkaline earth metal
salicylate.
14. A motorcycle as claimed in claim 13, wherein the alkali or
alkaline earth metal salicylate is the only metal containing
detergent in the lubricating oil composition.
15. A motorcycle as claimed in claim 1, wherein the lubricating oil
composition further comprises a viscosity modifier, which viscosity
modifier comprises a major amount of a star polymer viscosity
modifier.
16. A motorcycle as claimed in claim 15, wherein the viscosity
modifier comprises one or more star polymer viscosity modifier as
the only viscosity modifier in the lubricating oil composition.
17. A motorcycle as claimed in claim 1, wherein the lubricating oil
composition further comprises a phosphorus-containing additive
providing at least 800 ppm phosphorus to the lubricating oil
composition.
18. A method of operating a motorcycle having a four cycle engine
and a transmission including a clutch assembly, the engine
crankcase and the clutch assembly being lubricating by a
lubricating oil composition provided from a common sump, said
method comprising supplying to the engine crankcase and clutch
assembly a lubricating oil composition comprising a major amount of
oil of lubricating viscosity and minor amounts of (A) an oil
soluble molybdenum compound and (B) an ashless organic friction
modifier, wherein the lubricating oil composition comprises at
least 30 ppm and no more than 500 ppm of molybdenum from the
oil-soluble molybdenum compound (A).
19. (canceled)
20. (canceled)
21. (canceled)
22. A method of operating a motorcycle as claimed in claim 18,
wherein the oil-soluble molybdenum compound consists of either a
molybdenum dithiocarbamate or a molybdenum dithiophosphate or a
mixture thereof, as the sole source of molybdenum atoms in the
lubricating oil composition.
23. A method of operating a motorcycle as claimed in claim 18,
wherein the oil-soluble molybdenum compound consists of a
molybdenum dithiocarbamate, as the sole source of molybdenum atoms
in the lubricating oil composition.
24. A method of operating a motorcycle as claimed in claim 18,
wherein the ashless organic friction modifier (B) comprises at
least one of (a) a nitrogen-free organic friction modifier
comprising an ester formed by reacting carboxylic acids and
anhydrides with alkanols, (b) an aminic or amine-based friction
modifiers comprising alkoxylated mono- and di-amines, (c) an ester
formed as the reaction product of (i) a tertiary amine of the
formula R.sub.1R.sub.2R.sub.3N wherein R.sub.1, R.sub.2 and R.sub.3
represent aliphatic hydrocarbyl groups having 1 to 6 carbon atoms,
at least one of R.sub.1, R.sub.2 and R.sub.3 having a hydroxyl
group, with (ii) a saturated or unsaturated fatty acid having 10 to
30 carbon atoms, or a mixture thereof.
25. A method of operating a motorcycle as claimed in claim 18,
wherein the total amount of ashless organic friction modifier (B)
in the lubricating oil composition does not exceed 5 mass %, based
on the total mass of the lubricating oil composition.
26. A method of operating a motorcycle as claimed in claim 25,
wherein the total amount of ashless organic friction modifier (B)
in the lubricating oil composition does not exceed 5 mass %, based
on the total mass of the lubricating oil composition.
27. A method of operating a motorcycle as claimed in claim 18,
wherein the lubricating oil composition further comprises an
ashless dispersant additive.
28. A method of operating a motorcycle as claimed in claim 27,
wherein the ashless dispersant additive comprises a major amount of
an ashless dispersant made by the thermal process.
29. A method of operating a motorcycle as claimed in claim 18,
wherein the lubricating oil composition further comprises
metal-containing detergent, which metal containing detergent may be
an alkali or alkaline earth metal sulfonate, phenate or
salicylate.
30. A method of operating a motorcycle as claimed in claim 29,
wherein the metal containing detergent comprises an alkali or
alkaline earth metal salicylate.
31. A method of operating a motorcycle as claimed in claim 30,
wherein the alkali or alkaline earth metal salicylate is the only
metal containing detergent in the lubricating oil composition.
32. A method of operating a motorcycle as claimed in claim 18,
wherein the lubricating oil composition further comprises a
viscosity modifier, which viscosity modifier comprises a major
amount of a star polymer viscosity modifier.
33. A method of operating a motorcycle as claimed in claim 32,
wherein the viscosity modifier comprises one or more star polymer
viscosity modifier as the only viscosity modifier in the
lubricating oil composition.
34. A method of operating a motorcycle as claimed in claim 18,
wherein the lubricating oil composition further comprises a
phosphorus-containing additive providing at least 800 ppm
phosphorus to the lubricating oil composition.
35. A lubricating oil composition comprising a major amount of oil
of lubricating viscosity and minor amounts of (A) an oil soluble
molybdenum compound and (B) an ashless organic friction modifier,
which lubricating oil composition comprises at least 30 ppm and no
more than 500 ppm of molybdenum from the oil-soluble molybdenum
compound (A) and exhibits a JASO clutch friction of at least MA1
when measured according to the JASO T 903:2016 clutch friction
test.
36. A lubricating oil composition according to claim 35, wherein
the lubricating oil composition exhibits a JASO clutch friction of
at MA2 when measured according to the JASO T 903:2016 clutch
friction test.
37. (canceled)
38. (canceled)
39. (canceled)
40. (canceled)
41. (canceled)
42. (canceled)
43. A lubricating oil composition according to claim 35, wherein
the oil-soluble molybdenum compound consists of either a molybdenum
dithiocarbamate or a molybdenum dithiophosphate or a mixture
thereof, as the sole source of molybdenum atoms in the lubricating
oil composition.
44. A lubricating oil composition according to claim 43, wherein
the oil-soluble molybdenum compound consists of a molybdenum
dithiocarbamate, as the sole source of molybdenum atoms in the
lubricating oil composition.
45. A lubricating oil composition according to claim 35, wherein
the lubricating oil composition wherein the ashless organic
friction modifier (B) comprises at least one of (a) a nitrogen-free
organic friction modifier comprising an ester formed by reacting
carboxylic acids and anhydrides with alkanols, (b) an aminic or
amine-based friction modifiers comprising alkoxylated mono- and
di-amines, (c) an ester formed as the reaction product of (i) a
tertiary amine of the formula R.sub.1R.sub.2R.sub.3N wherein
R.sub.1, R.sub.2 and R.sub.3 represent aliphatic hydrocarbyl groups
having 1 to 6 carbon atoms, at least one of R.sub.1, R.sub.2 and
R.sub.3 having a hydroxyl group, with (ii) a saturated or
unsaturated fatty acid having 10 to 30 carbon atoms, or a mixture
thereof.
46. A lubricating oil composition according to claim 35, wherein
the total amount of ashless organic friction modifier (B) in the
lubricating oil composition does not exceed 5 mass %, based on the
total mass of the lubricating oil composition.
47. A lubricating oil composition according to claim 45, wherein
the total amount of ashless organic friction modifier (B) in the
lubricating oil composition does not exceed 5 mass %, based on the
total mass of the lubricating oil composition.
48. A lubricating oil composition according to claim 35, wherein
the lubricating oil composition further comprises an ashless
dispersant additive.
49. A lubricating oil composition according to claim 48, wherein
the ashless dispersant additive comprises a major amount of an
ashless dispersant made by the thermal process.
50. A lubricating oil composition according to claim 35, wherein
the lubricating oil composition further comprises metal-containing
detergent, which metal containing detergent may be an alkali or
alkaline earth metal sulfonate, phenate or salicylate.
51. A lubricating oil composition as claimed in claim 50, wherein
the metal containing detergent comprises an alkali or alkaline
earth metal salicylate.
52. A lubricating oil composition as claimed in claim 51, wherein
the alkali or alkaline earth metal salicylate is the only metal
containing detergent in the lubricating oil composition.
53. A lubricating oil composition according to claim 35, wherein
the lubricating oil composition further comprises a viscosity
modifier, which viscosity modifier comprises a major amount of a
star polymer viscosity modifier.
54. A lubricating oil composition as claimed in claim 53, wherein
the viscosity modifier comprises one or more star polymer viscosity
modifier as the only viscosity modifier in the lubricating oil
composition.
55. A lubricating oil composition according to claim 35, wherein
the lubricating oil composition further comprises a
phosphorus-containing additive providing at least 800 ppm
phosphorus to the lubricating oil composition.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to a motorcycle having a four
cycle engine and a transmission including a clutch assembly, the
engine crankcase and the clutch assembly being lubricating by a
lubricating oil provided from a common sump, and lubricating oil
compositions suitable for lubricating the engine crankcase and
clutch assembly of such motorcycles.
BACKGROUND OF THE INVENTION
[0002] In a typical motorcycle, a common sump lubricates the
engine, transmission and wet clutch. Such universal lubricating
fluids as used in motorcycles, therefore, must have a balance of
both desirable friction properties and lubricity properties. In
particular, whilst it is desirable to reduce friction in the engine
crankcase to improve fuel economy it is important to maintain
sufficient friction in the clutch assembly to allow it to function
efficiently.
[0003] It is well known to use molybdenum-containing additives as
friction modifiers in crankcase lubricants for passenger car engine
oils. However, use of molybdenum-containing additives in motorcycle
lubricants is problematic due to the need to maintain sufficient
friction in the clutch assembly.
[0004] This problem was considered in International patent
application number WO 2015/195614, which discloses a method of
operating a 4-stroke motorcycle engine comprising supplying to the
engine and clutch a lubricant comprising (a) an antimony
dialkyldithiocarbamate compound and (b) an ash-free friction
modifier comprising at least one of long chain fatty acid
derivatives of amines, long chain fatty esters, derivatives of long
chain fatty epoxides, fatty imidazolines; amine salts of
alkylphosphoric acids or fatty esters amides or imides of
hydroxyl-carboxylic acids, wherein the lubricating composition
comprise less than 50 weight percent of a synthetic ester having a
kinematic viscosity of 5.5 to 25 mm.sup.2/s when measured at
100.degree. C. The lubricant of WO 2015/195614 may also comprise a
N-containing molybdenum additive other than a molybdenum
dithiocarbamate, which latter may result in undesirable friction
properties.
[0005] However, it has been discovered that a lubricant comprising
molybdenum additives, including, but not limited to molybdenum
dithiocarbamate complexes, can be successfully used to lubricate
the engine crankcase and the clutch assembly from a common sump of
a motorcycle having a four cycle engine by including an ash-free
friction modifier in the lubricant.
SUMMARY OF THE INVENTION
[0006] According to a first aspect the present invention provides a
motorcycle having a four cycle engine and a transmission including
a clutch assembly, the engine crankcase and the clutch assembly
being lubricated by a lubricating oil composition provided from a
common sump, wherein said lubricating oil composition comprises a
major amount of oil of lubricating viscosity and minor amounts of
(A) an oil soluble molybdenum compound and (B) an ashless organic
friction modifier.
[0007] According to a second aspect the present invention further
provides a method of operating a motorcycle having a four cycle
engine and a transmission including a clutch assembly, the engine
crankcase and the clutch assembly being lubricating by a
lubricating oil composition provided from a common sump, said
method comprising supplying to the engine crankcase and clutch
assembly a lubricating oil composition comprising a major amount of
oil of lubricating viscosity and minor amounts of (A) an oil
soluble molybdenum compound and (B) an ashless organic friction
modifier.
[0008] According to a third aspect the present invention also
provides a lubricating oil composition comprising a major amount of
oil of lubricating viscosity and minor amounts of (A) an oil
soluble molybdenum compound and (B) an ashless organic friction
modifier, which lubricating oil composition exhibits a JASO clutch
friction of at least MA1 when measured according to the JASO T
903:2016 clutch friction test. In a preferred embodiment the
lubricating oil composition of the third aspect of the invention
exhibits a JASO clutch friction of at MA2 when measured according
to the JASO T 903:2016 clutch friction test.
[0009] In this specification, the following words and expressions,
if and when used, have the meanings given below: [0010] "active
ingredients" or "(a.i.)" refers to additive material that is not
diluent or solvent; [0011] "comprising" or any cognate word
specifies the presence of stated features, steps, or integers or
components, but does not preclude the presence or addition of one
or more other features, steps, integers, components or groups
thereof. The expressions "consists of", or "consists essentially
of" or cognates may be embraced within "comprises" or cognates,
wherein "consists essentially of" permits inclusion of substances
not materially affecting the characteristics of the composition to
which it applies; [0012] "hydrocarbyl" means a chemical group of a
compound that contains hydrogen and carbon atoms and that is bonded
to the remainder of the compound directly via a carbon atom. The
group may contain one or more atoms other than carbon and hydrogen
provided they do not affect the essentially hydrocarbyl nature of
the group. Those skilled in the art will be aware of suitable
groups (e.g., halo, especially chloro and fluoro, amino, alkoxyl,
mercapto, alkylmercapto, nitro, nitroso, sulfoxy, etc.).
Preferably, the group consists essentially of hydrogen and carbon
atoms, unless specified otherwise. Preferably, the hydrocarbyl
group comprises an aliphatic hydrocarbyl group. The term
"hydrocarbyl" includes "alkyl", "alkenyl", "allyl" and "aryl" as
defined herein; [0013] "alkyl" means a C.sub.1 to C.sub.30 alkyl
group which is bonded to the remainder of the compound directly via
a single carbon atom. Unless otherwise specified, alkyl groups may,
when there are a sufficient number of carbon atoms, be linear (i.e.
unbranched) or branched, be cyclic, acyclic or part cyclic/acyclic.
Preferably, the alkyl group comprises a linear or branched acyclic
alkyl group. Representative examples of alkyl groups include, but
are not limited to, methyl, ethyl, n-propyl, iso-propyl, n-butyl,
sec-butyl, iso-butyl, tert-butyl, n-pentyl, iso-pentyl, neo-pentyl,
hexyl, heptyl, octyl, dimethyl hexyl, nonyl, decyl, undecyl,
dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl,
octadecyl, nonadecyl, icosyl and triacontyl; [0014] "aryl" means a
C.sub.6 to C.sub.18, preferably C.sub.6 to C.sub.10, aromatic
group, optionally substituted by one or more alkyl groups, halo,
hydroxyl, alkoxy and amino groups, which is bonded to the remainder
of the compound directly via a single carbon atom. Preferred aryl
groups include phenyl and naphthyl groups and substituted
derivatives thereof, especially phenyl and alkyl substituted
derivatives thereof; [0015] "alkenyl" means a C.sub.2 to C.sub.30,
preferably a C.sub.2 to C.sub.12, group which includes at least one
carbon to carbon double bond and is bonded to the remainder of the
compound directly via a single carbon atom, and is otherwise
defined as "alkyl"; [0016] "alkylene" means a C.sub.2 to C.sub.20,
preferably a C.sub.2 to C.sub.10, more preferably a C.sub.2 to
C.sub.6 bivalent saturated acyclic aliphatic radical which may be
linear or branched. Representative examples of alkylene include
ethylene, propylene, butylene, isobutylene, pentylene, hexylene,
heptylene, octylene, nonylene, decylene, 1-methyl ethylene, 1-ethyl
ethylene, 1-ethyl-2-methyl ethylene, 1,1-dimethyl ethylene and
1-ethyl propylene; [0017] "polyol" means an alcohol which includes
two or more hydroxyl functional groups (i.e. a polyhydric alcohol)
but excludes a "polyalkylene glycol" (component B(ii)) which is
used to form the oil-soluble or oil-dispersible polymeric friction
modifier. More specifically, the term "polyol" embraces a diol,
triol, tetrol, and/or related dimers or chain extended polymers of
such compounds. Even more specifically, the term "polyol" embraces
glycerol, neopentyl glycol, trimethylolethane, trimethylolpropane,
trimethylolbutane, pentaerythritol, dipentaerythritol,
tripentaerythritol and sorbitol; [0018] "polycarboxylic acid" means
an organic acid, preferably a hydrocarbyl acid, which includes 2 or
more carboxylic acid functional groups. The term "polycarboxylic
acid" embraces di-, tri- and tetra-carboxylic acids; [0019] "halo"
or "halogen" includes fluoro, chloro, bromo and iodo; [0020]
"oil-soluble" or "oil-dispersible", or cognate terms, used herein
do not necessarily indicate that the compounds or additives are
soluble, dissolvable, miscible, or are capable of being suspended
in the oil in all proportions. These do mean, however, that they
are, for example, soluble or stably dispersible in oil to an extent
sufficient to exert their intended effect in the environment in
which the oil is employed. Moreover, the additional incorporation
of other additives may also permit incorporation of higher levels
of a particular additive, if desired; [0021] "ashless" in relation
to an additive means the additive does not include a metal; [0022]
"ash-containing" in relation to an additive means the additive
includes a metal; "major amount" means in excess of 50 mass % of a
composition expressed in respect of the stated component and in
respect of the total mass of the composition, reckoned as active
ingredient of the component; [0023] "minor amount" means less than
50 mass % of a composition, expressed in respect of the stated
additive and in respect of the total mass of the composition,
reckoned as active ingredient of the additive; [0024] "effective
minor amount" in respect of an additive means an amount of such an
additive in a lubricating oil composition so that the additive
provides the desired technical effect; [0025] "ppm" means parts per
million by mass, based on the total mass of the lubricating oil
composition; [0026] "metal content" of the lubricating oil
composition or of an additive component, for example detergent
metal, molybdenum or boron content or total metal content of the
lubricating oil composition (i.e. the sum of all individual metal
contents), is measured by ASTM D5185; [0027] "TBN" in relation to
an additive component or of a lubricating oil composition of the
present invention, means total base number (mg KOH/g) as measured
by ASTM D2896; [0028] "KV.sub.100" means kinematic viscosity at
100.degree. C. as measured by ASTM D445; [0029] "phosphorus
content" is measured by ASTM D5185; [0030] "sulfur content" is
measured by ASTM D2622; and, [0031] "sulfated ash content" is
measured by ASTM D874.
[0032] All percentages reported are mass % on an active ingredient
basis, i.e. without regard to carrier or diluent oil, unless
otherwise stated.
[0033] Also, it will be understood that various components used,
essential as well as optimal and customary, may react under
conditions of formulation, storage or use and that the invention
also provides the product obtainable or obtained as a result of any
such reaction.
[0034] Further, it is understood that any upper and lower quantity,
range and ratio limits set forth herein may be independently
combined.
[0035] Also, it will be understood that the preferred features of
each aspect of the present invention are regarded as preferred
features of every other aspect of the present invention.
BRIEF DESCRIPTION OF THE FIGURES
[0036] FIG. 1 represents graphically, the results shown in Table
2.
[0037] FIG. 2 represents graphically, the results shown in Table
3.
[0038] FIGS. 3-6 represent graphically, the results of Example
2.
[0039] FIG. 7 represents graphically, the results shown in Table
5.
[0040] FIG. 8 represents graphically, the results shown in Table
6.
DETAILED DESCRIPTION OF THE INVENTION
Oil of Lubricating Viscosity
[0041] The oil of lubricating viscosity (sometimes referred to as
"base stock" or "base oil") is the primary liquid constituent of a
lubricant, into which additives and possibly other oils are
blended, for example to produce a final lubricant (or lubricant
composition). A base oil is useful for making concentrates as well
as for making lubricating oil compositions therefrom, and may be
selected from natural (vegetable, animal or mineral) and synthetic
lubricating oils and mixtures thereof.
[0042] The base stock groups are defined in the American Petroleum
Institute (API) publication "Engine Oil Licensing and Certification
System", Industry Services Department, Fourteenth Edition, December
1996, Addendum 1, December 1998. Typically, the base stock will
have a viscosity preferably of 3-12, more preferably 4-10, most
preferably 4.5-8, mm.sup.2/s (cSt) at 100.degree. C.
[0043] Definitions for the base stocks and base oils in this
invention are the same as those found in the American Petroleum
Institute (API) publication "Engine Oil Licensing and Certification
System", Industry Services Department, Fourteenth Edition, December
1996, Addendum 1, December 1998. Said publication categorizes base
stocks as follows: [0044] a) Group I base stocks contain less than
90 percent saturates and/or greater than 0.03 percent sulphur and
have a viscosity index greater than or equal to 80 and less than
120 using the test methods specified in Table E-1. [0045] b) Group
II base stocks contain greater than or equal to 90 percent
saturates and less than or equal to 0.03 percent sulphur and have a
viscosity index greater than or equal to 80 and less than 120 using
the test methods specified in Table E-1. [0046] c) Group III base
stocks contain greater than or equal to 90 percent saturates and
less than or equal to 0.03 percent sulphur and have a viscosity
index greater than or equal to 120 using the test methods specified
in Table E-1. [0047] d) Group IV base stocks are polyalphaolefins
(PAO). [0048] e) Group V base stocks include all other base stocks
not included in Group I, II, III, or IV.
TABLE-US-00001 [0048] TABLE E-1 Analytical Methods for Base Stock
Property Test Method Saturates ASTM D 2007 Viscosity Index ASTM D
2270 Sulphur ASTM D 2622 ASTM D 4294 ASTM D 4927 ASTM D 3120
[0049] Other oils of lubricating viscosity which may be included in
the lubricating oil composition are detailed as follows.
[0050] Natural oils include animal and vegetable oils (e.g. castor
and lard oil), liquid petroleum oils and hydrorefined,
solvent-treated mineral lubricating oils of the paraffinic,
naphthenic and mixed paraffinic-naphthenic types. Oils of
lubricating viscosity derived from coal or shale are also useful
base oils.
[0051] Synthetic lubricating oils include hydrocarbon oils such as
polymerized and interpolymerized olefins (e.g. polybutylenes,
polypropylenes, propylene-isobutylene copolymers, chlorinated
polybutylenes, poly(1-hexenes), poly(1-octenes), poly(1-decenes));
alkylbenzenes (e.g. dodecylbenzenes, tetradecylbenzenes,
dinonylbenzenes, di(2-ethylhexyl)benzenes); polyphenols (e.g.
biphenyls, terphenyls, alkylated polyphenols); and alkylated
diphenyl ethers and alkylated diphenyl sulfides and the
derivatives, analogues and homologues thereof.
[0052] Another suitable class of synthetic lubricating oils
comprises the esters of dicarboxylic acids (e.g. phthalic acid,
succinic acid, alkyl succinic acids and alkenyl succinic acids,
maleic acid, azelaic acid, suberic acid, sebasic acid, fumaric
acid, adipic acid, linoleic acid dimer, malonic acid, alkylmalonic
acids, alkenyl malonic acids) with a variety of alcohols (e.g.
butyl alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl
alcohol, ethylene glycol, diethylene glycol monoether, propylene
glycol). Specific examples of these esters include dibutyl adipate,
di(2-ethylhexyl) sebacate, di-n-hexyl fumarate, dioctyl sebacate,
diisooctyl azelate, diisodecyl azelate, dioctyl phthalate, didecyl
phthalate, dieicosyl sebacate, the 2-ethylhexyl diester of linoleic
acid dimer, and the complex ester formed by reacting one mole of
sebacic acid with two moles of tetraethylene glycol and two moles
of 2-ethylhexanoic acid.
[0053] Esters useful as synthetic oils also include those made from
C.sub.5 to C.sub.12 monocarboxylic acids and polyols, and polyol
ethers such as neopentyl glycol, trimethylolpropane,
pentaerythritol, dipentaerythritol and tripentaerythritol.
[0054] Unrefined, refined and re-refined oils can be used in the
compositions of the present invention. Unrefined oils are those
obtained directly from a natural or synthetic source without
further purification treatment. For example, a shale oil obtained
directly from retorting operations, a petroleum oil obtained
directly from distillation or ester oil obtained directly from an
esterification process and used without further treatment would be
unrefined oil. Refined oils are similar to the unrefined oils
except they have been further treated in one or more purification
steps to improve one or more properties. Many such purification
techniques, such as distillation, solvent extraction, acid or base
extraction, filtration and percolation are known to those skilled
in the art. Re-refined oils are obtained by processes similar to
those used to obtain refined oils applied to refined oils which
have been already used in service. Such re-refined oils are also
known as reclaimed or reprocessed oils and often are additionally
processed by techniques for approval of spent additive and oil
breakdown products.
[0055] Other examples of base oil are gas-to-liquid ("GTL") base
oils, i.e. the base oil may be an oil derived from Fischer-Tropsch
synthesised hydrocarbons made from synthesis gas containing H.sub.2
and CO using a Fischer-Tropsch catalyst. These hydrocarbons
typically require further processing in order to be useful as a
base oil. For example, they may, by methods known in the art, be
hydroisomerized; hydrocracked and hydroisomerized; dewaxed; or
hydroisomerized and dewaxed.
[0056] Whilst the composition of the base oil will depend upon the
particular application of the lubricating oil composition and the
oil formulator will chose the base oil to achieve desired
performance characteristics at reasonable cost, the oil of a
lubricating viscosity of the lubricating oil composition according
to all aspects of the present invention typically comprises Group
II or Group III base oil in the majority. The oil of a lubricating
viscosity of the lubricating oil composition according to all
aspects of the present invention may comprise at least 50 mass %
Group III and/or Group II base oil, such as at least 70 mass % or
even at least 80 mass % Group III and/or Group II base oil, based
on the mass of the oil of lubricating viscosity in the lubricating
oil composition. The oil of lubricating viscosity may comprise 100
mass % of Group 111 and/or Group 11 base oil, based on the mass of
the oil of lubricating viscosity in the lubricating oil
composition.
[0057] Preferably, the volatility of the oil of lubricating
viscosity or oil blend, as measured by the NOACK test (ASTM D5800),
is less than or equal to 20%, preferably less than or equal to 16%,
preferably less than or equal to 12%, more preferably less than or
equal to 10%. Preferably, the viscosity index (VI) of the oil of
lubricating viscosity is at least 95, preferably at least 110, more
preferably up to 120, even more preferably at least 120, even more
preferably at least 125, most preferably from about 130 to 140.
[0058] Preferably, the oil of lubricating viscosity is present in
an amount of greater than 55 mass %, more preferably greater than
60 mass %, even more preferably greater than 70 mass %, based on
the total mass of the lubricating oil composition. Preferably, the
oil of lubricating viscosity is present in an amount of less than
98 mass %, more preferably less than 95 mass %, even more
preferably less than 90 mass %, based on the total mass of the
lubricating oil composition.
[0059] The lubricating oil composition of each aspect of the
present invention may be a multigrade oil identified by the
viscometric descriptor SAE 20WX, SAE 15WX, SAE 10WX, SAE 5WX or SAE
OWX, where X represents any one of 20, 30, 40 and 50; the
characteristics of the different viscometric grades can be found in
the SAE J300 classification. In an embodiment of each aspect of the
invention, independently of the other embodiments, the lubricating
oil composition is in the form of an SAE 10WX, SAE 5WX or SAE OWX,
preferably in the form of a SAE 10WX or SAE 5WX viscosity grade,
wherein X represents any one of 20, 30, 40 and 50. Preferably X is
30 or 40.
Oil-Soluble Molybdenum Compound (A)
[0060] For the lubricating oil compositions of all aspects of the
present invention, any suitable oil-soluble or oil-dispersible
molybdenum compound having friction modifying properties in
lubricating oil compositions may be employed.
[0061] Preferably, the oil-soluble or oil-dispersible molybdenum
compound is an oil-soluble or oil-dispersible organo-molybdenum
compound. As examples of such organo-molybdenum compounds, there
may be mentioned molybdenum dithiocarbamates, molybdenum
dithiophosphates, molybdenum dithiophosphinates, molybdenum
xanthates, molybdenum thioxanthates, molybdenum sulfides, and the
like, and mixtures thereof. Particularly preferred are molybdenum
dithiocarbamates, molybdenum dialkyldithiophosphates, molybdenum
alkyl xanthates and molybdenum alkylthioxanthates. Especially
preferred organo-molybdenum compounds are molybdenum
dithiocarbamates. In an embodiment of the present invention the
oil-soluble or oil-dispersible molybdenum compound consists of
either a molybdenum dithiocarbamate or a molybdenum dithiophosphate
or a mixture thereof, as the sole source of molybdenum atoms in the
lubricating oil composition. In an alternative embodiment of the
present invention the oil-soluble or oil-dispersible molybdenum
compound consists of a molybdenum dithiocarbamate, as the sole
source of molybdenum atoms in the lubricating oil composition.
[0062] The molybdenum compound may be mono-, di-, tri- or
tetra-nuclear. Di-nuclear and tri-nuclear molybdenum compounds are
preferred.
[0063] Suitable dinuclear or dimeric molybdenum
dialkyldithiocarbamate are represented by the following
formula:
##STR00001##
wherein R.sub.1 through R.sub.4 independently denote a straight
chain, branched chain or aromatic hydrocarbyl group having 1 to 24
carbon atoms; and X.sub.1 through X.sub.4 independently denote an
oxygen atom or a sulfur atom. The four hydrocarbyl groups, R.sub.1
through R.sub.4, may be identical or different from one
another.
[0064] Other molybdenum compounds useful in the compositions of
this invention are organo-molybdenum compounds of the formulae
Mo(ROCS.sub.2).sub.4 and Mo(RSCS.sub.2).sub.4, wherein R is an
organo group selected from the group consisting of alkyl, aryl,
aralkyl and alkoxyalkyl, generally of from 1 to 30 carbon atoms,
and preferably 2 to 12 carbon atoms and most preferably alkyl of 2
to 12 carbon atoms. Especially preferred are the
dialkyldithiocarbamates of molybdenum.
[0065] Suitable tri-nuclear organo-molybdenum compounds include
those of the formula Mo.sub.3S.sub.kL.sub.nQ.sub.z and mixtures
thereof wherein L are independently selected ligands having organo
groups with a sufficient number of carbon atoms to render the
compound soluble or dispersible in the oil, n is from 1 to 4, k
varies from 4 through 7, Q is selected from the group of neutral
electron donating compounds such as water, amines, alcohols,
phosphines, and ethers, and z ranges from 0 to 5 and includes
non-stoichiometric values. At least 21 total carbon atoms should be
present among all the ligands' organo groups, such as at least 25,
at least 30, or at least 35 carbon atoms.
[0066] The ligands are independently selected from the group
of:
##STR00002##
and mixtures thereof, wherein X, X.sub.1, X.sub.3, and Y are
independently selected from the group of oxygen and sulfur, and
wherein R.sub.1, R.sub.2, and R are independently selected from
hydrogen and organo groups that may be the same or different.
Preferably, the organo groups are hydrocarbyl groups such as alkyl
(e.g., in which the carbon atom attached to the remainder of the
ligand is primary or secondary), aryl, substituted aryl and ether
groups. More preferably, each ligand has the same hydrocarbyl
group.
[0067] Importantly, the organo groups of the ligands have a
sufficient number of carbon atoms to render the compound soluble or
dispersible in the oil. For example, the number of carbon atoms in
each group will generally range between about 1 to about 100,
preferably from about 1 to about 30, and more preferably between
about 4 to about 20.
[0068] Preferred ligands include dialkyldithiophosphate,
alkylxanthate, and dialkyldithiocarbamate, and of these
dialkyldithiocarbamate is more preferred. Organic ligands
containing two or more of the above functionalities are also
capable of serving as ligands and binding to one or more of the
cores. Those skilled in the art will realize that formation of the
compounds of the present invention requires selection of ligands
having the appropriate charge to balance the core's charge.
[0069] Compounds having the formula Mo.sub.3S.sub.kL.sub.nQ.sub.z
have cationic cores surrounded by anionic ligands and are
represented by structures such as
##STR00003##
and have net charges of +4. Consequently, in order to solubilize
these cores the total charge among all the ligands must be -4. Four
mono-anionic ligands are preferred. Without wishing to be bound by
any theory, it is believed that two or more tri-nuclear cores may
be bound or interconnected by means of one or more ligands and the
ligands may be multidentate. This includes the case of a
multidentate ligand having multiple connections to a single core.
It is believed that oxygen and/or selenium may be substituted for
sulfur in the core(s).
[0070] Oil-soluble or oil-dispersible tri-nuclear molybdenum
compounds can be prepared by reacting in the appropriate
liquid(s)/solvent(s) a molybdenum source such as
(NH.sub.4)Mo.sub.3S.sub.13.n(H.sub.2O), where n varies between 0
and 2 and includes non-stoichiometric values, with a suitable
ligand source such as a tetralkylthiuram disulfide. Other
oil-soluble or dispersible tri-nuclear molybdenum compounds can be
formed during a reaction in the appropriate solvent(s) of a
molybdenum source such as of
(NH.sub.4)Mo.sub.3S.sub.13.n(H.sub.2O), a ligand source such as
tetralkylthiuam disullide, dialkyldithiocarbamate, or
dialkyldithiophosphate, and a sulfur abstracting agent such as
cyanide ions, sulfite ions, or substituted phosphines.
Alternatively, a tri-nuclear molybdenum-sulfur halide salt such as
[M'].sub.2[Mo.sub.3S.sub.7A.sub.6], where M' is a counter ion, and
A is a halogen such as Cl, Br, or I, may be reacted with a ligand
source such as a dialkyldithiocarbamate or dialkyldithiophosphate
in the appropriate liquid(s)/solvent(s) to form an oil-soluble or
dispersible trinuclear molybdenum compound. The appropriate
liquid/solvent may be, for example, aqueous or organic.
[0071] A compound's oil solubility or dispersibility may be
influenced by the number of carbon atoms in the ligand's organo
groups. Preferably, at least 21 total carbon atoms should be
present among all the ligands' organo groups. Preferably, the
ligand source chosen has a sufficient number of carbon atoms in its
organo groups to render the compound soluble or dispersible in the
lubricating composition.
[0072] The amount of oil-soluble molybdenum compound will depend
upon the particular performance requirements of the lubricating oil
composition. Suitably, the lubricating oil composition of all
aspects of the present invention contains the molybdenum compound
in an amount providing the composition with at least 30 ppm or at
least 50 ppm of molybdenum (ASTM D5185). The lubricating oil
composition of all aspects of the present invention may contain the
molybdenum compound in an amount providing the composition with up
to 1000 ppm, or up to 500 ppm or up to 200 ppm, or up to 150 ppm of
molybdenum (ASTM D5185).
Ashless Organic Friction Modifier (B)
[0073] Ashless friction modifiers suitable for use in the
lubricating oil composition of all aspects of the present invention
include nitrogen-free organic friction modifiers and include esters
formed by reacting carboxylic acids and anhydrides with alkanols.
Other suitable friction modifiers include a polar terminal group
(e.g. carboxyl or hydroxyl) covalently bonded to an oleophilic
hydrocarbon chain. Esters of carboxylic acids and anhydrides with
alkanols are described in U.S. Pat. No. 4,702,850. Examples of
other conventional organic friction modifiers are described by M.
Belzer in the "Journal of Tribology" (1992), Vol. 114, pp. 675-682
and M. Belzer and S. Jahanmir in "Lubrication Science" (1988), Vol.
1, pp. 3-26.
[0074] Preferred organic ashless nitrogen-free friction modifiers
are esters or ester-based; a particularly preferred organic ashless
nitrogen-free friction modifier is glycerol monooleate (GMO).
[0075] Other preferred ashless organic friction modifiers include
alkenyl substituted anhydrides, such as octadecenyl succinic
anhydride.
[0076] Ashless aminic or amine-based friction modifiers may also be
used and include oil-soluble alkoxylated mono- and di-amines, which
improve boundary layer lubrication. One common class of such metal
free, nitrogen-containing friction modifier comprises ethoxylated
alkyl amines. They may be in the form of an adduct or reaction
product with a boron compound such as a boric oxide, boron halide,
metaborate, boric acid or a mono-, di- or tri-alkyl borate. Another
metal free, nitrogen-containing friction modifier is an ester
formed as the reaction product of (i) a tertiary amine of the
formula R.sub.1R.sub.2R.sub.3N wherein R.sub.1, R.sub.2 and R.sub.3
represent aliphatic hydrocarbyl, preferably alkyl, groups having 1
to 6 carbon atoms, at least one of R.sub.1, R.sub.2 and R.sub.3
having a hydroxyl group, with (ii) a saturated or unsaturated fatty
acid having 10 to 30 carbon atoms. Preferably, at least one of
R.sub.1, R.sub.2 and R.sub.3 is an alkyl group. Preferably, the
tertiary amine will have at least one hydroxyalkyl group having 2
to 4 carbon atoms.
[0077] The ester may be a mono-, di- or tri-ester or a mixture
thereof, depending on how many hydroxyl groups are available for
esterification with the acyl group of the fatty acid. The ashless
organic friction modifier of all aspects of the present invention
may comprise a mixture of esters formed as the reaction product of
(i) a tertiary hydroxy amine of the formula R.sub.1R.sub.2R.sub.3N
wherein R.sub.1, R.sub.2 and R.sub.3 may be a C.sub.2-C.sub.4
hydroxy alkyl group with (ii) a saturated or unsaturated fatty acid
having 10 to 30 carbon atoms, with a mixture of esters so formed
comprising at least 30-60 mass %, preferably 45-55 mass % diester,
such as 50 mass % diester, 10-40 mass %, preferably 20-30 mass %
monoester, e.g. 25 mass % monoester, and 10-40 mass %, preferably
20-30 mass % triester, such as 25 mass % triester. Suitably, the
ester is a mono-, di- or tri-carboxylic acid ester of
triethanolamine and mixtures thereof.
[0078] Typically, the total amount of ashless organic friction
modifier (B) in the lubricating oil composition of all aspects of
the present invention does not exceed 5 mass %, based on the total
mass of the lubricating oil composition and preferably does not
exceed 2 mass % and more preferably does not exceed 0.5 mass %.
Ashless Dispersant (C)
[0079] The lubricating oil of all aspects of the present invention
may also comprise a dispersant additive.
[0080] A dispersant is an additive whose primary function is to
hold solid and liquid contaminations in suspension, thereby
passivating them and reducing engine deposits at the same time as
reducing sludge depositions. For example, a dispersant maintains in
suspension oil-insoluble substances that result from oxidation
during use of the lubricant, thus preventing sludge flocculation
and precipitation or deposition on metal parts of the engine.
[0081] Dispersants are usually "ashless", as mentioned above, being
non-metallic organic materials that form substantially no ash on
combustion, in contrast to metal-containing, and hence ash-forming
materials. They comprise a long hydrocarbon chain with a polar
head, the polarity being derived from inclusion of e.g. an O, P, or
N atom. The hydrocarbon is an oleophilic group that confers
oil-solubility, having, for example 40 to 500 carbon atoms. Thus,
ashless dispersants may comprise an oil-soluble polymeric
backbone.
[0082] The ashless dispersant suitable for all aspects of the
present invention is preferably an ashless, nitrogen-containing
dispersant.
[0083] Suitable ashless dispersant may be made from polyalkenes
that have been functionalised exclusively by the thermal "ene"
reaction, a known reaction. Such polyalkenes are mixtures having
predominantly terminal vinylidene groups, such at least 65, e.g.
70, more preferably at least 85, %. As an example, there may be
mentioned a polyalkene known as highly reactive polyisobutene
(HR-PIB), which is commercially available under the tradename
Glissopal.RTM. (ex BASF). U.S. Pat. No. 4,152,499 describes the
preparations of such polymers.
[0084] Alternatively, the ashless dispersant may be made from
polyalkenes that have been functionalised by the so-called
chlorination method, which results in a product where minor
percentage of its polymer chains (e.g. less than 20%) have terminal
vinylidene groups.
[0085] Preferred monounsaturated reactants that may be used to
functionalize the polyalkene comprise mono- and dicarboxylic acid
material, i.e., acid, anhydride, or acid ester material, including
(i) monounsaturated C.sub.4 to C.sub.10 dicarboxylic acid wherein
(a) the carboxyl groups are vicinyl, (i.e., located on adjacent
carbon atoms) and (b) at least one, preferably both, of said
adjacent carbon atoms are part of said mono unsaturation; (ii)
derivatives of (i) such as anhydrides or C.sub.1 to C.sub.5 alcohol
derived mono- or diesters of (i); (iii) monounsaturated C.sub.3 to
C.sub.10 monocarboxylic acid wherein the carbon-carbon double bond
is conjugated with the carboxy group, i.e., of the structure
--C.dbd.C--CO--; and (iv) derivatives of (iii) such as C.sub.1 to
C.sub.5 alcohol derived mono- or diesters of (iii). Mixtures of
monounsaturated carboxylic materials (i)-(iv) also may be used.
Upon reaction with the polyalkene, the monounsaturation of the
monounsaturated carboxylic reactant becomes saturated. Thus, for
example, maleic anhydride becomes polyalkene-substituted succinic
anhydride, and acrylic acid becomes polyalkene-substituted
propionic acid. Exemplary of such monounsaturated carboxylic
reactants are fumaric acid, itaconic acid, maleic acid, maleic
anhydride, acrylic acid, methacrylic acid, crotonic acid, cinnamic
acid, and lower alkyl (e.g., C.sub.1 to C.sub.4 alkyl) acid esters
of the foregoing, e.g., methyl maleate, ethyl fumarate, and methyl
fumarate.
[0086] To provide the required functionality, monounsaturated
carboxylic reactants, preferably maleic anhydride, typically will
be used in an amount ranging from equimolar to 100, preferably 5 to
50, wt. % excess, based on the moles of polyalkene. Unreacted
excess monounsaturated carboxylic reactant can be removed from the
final dispersant product by, for example, stripping, usually under
vacuum, if required.
[0087] The functionalised oil-soluble polyalkene is then
derivatized with a nucleophilic reactant, such as an amine,
amino-alcohol, alcohol, or mixture thereof, to form a corresponding
derivative containing the dispersant. Useful amine compounds for
derivatizing functionalized polymers comprise at least one amine
and can comprise one or more additional amine or other reactive or
polar groups. These amines may be hydrocarbyl amines or may be
predominantly hydrocarbyl amines in which the hydrocarbyl group
includes other groups, e.g., hydroxy groups, alkoxy groups, amide
groups, nitriles and imidazoline groups. Particularly useful amine
compounds include mono- and polyamines, e.g., polyalkene and
polyoxyalkylene polyamines of 2 to 60, such as 2 to 40 (e.g., 3 to
20), total carbon atoms having 1 to 12, such as 3 to 12, preferably
3 to 9, most preferably 6 to 7, nitrogen atoms per molecule.
Mixtures of amine compounds may advantageously be used. Preferred
amines are aliphatic saturated amines, including, for example,
1,2-diaminoethane; 1,3-diaminopropane; 1,4-diaminobutane;
1,6-diaminohexane; polyethylene amines such as diethylene triamine;
triethylene tetramine; tetraethylene pentamine; and
polypropyleneamines such as 1,2-propylene diamine; and
di-(1,2-propylene)triamine. Such polyamine mixtures, known as PAM,
are commercially available. Particularly preferred polyamine
mixtures are mixtures derived by distilling the light ends from PAM
products. The resulting mixtures, known as "heavy" PAM, or HPAM,
are also commercially available. The properties and attributes of
both PAM and/or HPAM are described, for example, in U.S. Pat. Nos.
4,938,881; 4,927,551; 5,230,714; 5,241,003; 5,565,128; 5,756,431;
5,792,730; and 5,854,186.
[0088] Other useful amine compounds include: alicyclic diamines
such as 1,4-di(aminomethyl) cyclohexane and heterocyclic nitrogen
compounds such as imidazolines. Another useful class of amines is
the polyamido and related amido-amines as disclosed in U.S. Pat.
Nos. 4,857,217; 4,956,107; 4,963,275; and 5,229,022. Also usable is
tris(hydroxymethyl)amino methane (TAM) as described in U.S. Pat.
Nos. 4,102,798; 4,113,639; 4,116,876; and UK 989,409. Dendrimers,
star-like amines, and comb-structured amines may also be used.
Similarly, condensed amines, as described in U.S. Pat. No.
5,053,152 may be used. The functionalized polymer is reacted with
the amine compound using conventional techniques as described, for
example, in U.S. Pat. Nos. 4,234,435 and 5,229,022, as well as in
EP-A-208,560.
[0089] A dispersant of the present invention preferably comprises
at least one dispersant that is derived from
polyalkenyl-substituted mono- or dicarboxylic acid, anhydride or
ester, which has 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.M.sub.n)/((112,200.times.A.I.)-(SAP.times.MW)) (1)
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); M.sub.n is the
number average molecular weight of the starting olefin polymer,
A.I. is the percent active ingredient of the succinic-containing
reaction product (the remainder being unreacted olefin polymer,
succinic anhydride and diluent); and MW is the molecular weight of
the mono- or dicarboxylic acid producing moieties (e.g., 98 for
maleic anhydride).
[0090] Generally, each mono- or dicarboxylic acid-producing moiety
will react with a nucleophilic group (amine, alcohol, amide or
ester polar moieties) and the number of functional groups in the
polyalkenyl-substituted carboxylic acylating agent will determine
the number of nucleophilic groups in the finished dispersant.
[0091] The polyalkenyl moiety of the dispersant of the present
invention 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.
[0092] Polymer molecular weight, specifically M.sub.n, 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 (see,
e.g., ASTM D3592).
[0093] The polyalkenyl moiety in a dispersant of the present
invention preferably has a narrow molecular weight distribution
(MWD), also referred to as polydispersity, as determined by the
ratio of weight average molecular weight (M.sub.w) to number
average molecular weight (M.sub.n). Polymers having a
M.sub.w/M.sub.n 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.
[0094] Suitable polyalkenes employed in the formation of the
dispersants of the present invention include homopolymers,
interpolymers or lower molecular weight hydrocarbons. One family of
such polymers comprise polymers of ethylene and/or at least one
C.sub.3 to C.sub.28 alpha-olefin having the formula
H.sub.2C.dbd.CHR.sup.1 wherein R.sup.1 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 R.sup.1 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
[0095] 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 C.sub.4 refinery stream having a butene content
of 35 to 75% by wt., and an isobutene content of 30 to 60% by wt.,
by the thermal "ene" reaction. 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 as described above.
[0096] The dispersant(s) of the invention are preferably mono- or
bis-succinimides.
[0097] The dispersant(s) of the present invention can be borated by
conventional means, as generally taught in U.S. Pat. Nos.
3,087,936, 3,254,025 and 5,430,105. Boration of the dispersant is
readily accomplished by treating an acyl nitrogen-containing
dispersant with a boron compound such as boron oxide, boron halide
boron acids, and esters of boron acids, in an amount sufficient to
provide from 0.1 to 20 atomic proportions of boron for each mole of
acylated nitrogen composition.
[0098] The boron, which appears in the product as dehydrated boric
acid polymers (primarily (HBO.sub.2).sub.3), is believed to attach,
for example, to dispersant imides and diimides as amine salts,
e.g., the metaborate salt of the diimide. Boration can be carried
out by adding a sufficient quantity of a boron compound, preferably
boric acid, usually as a slurry, to the acyl nitrogen compound and
heating with stirring at from 135 C to 190, e.g., 140 to 170,
.degree. C., for from 1 to 5 hours, followed by nitrogen stripping.
Alternatively, the boron treatment can be conducted by adding boric
acid to a hot reaction mixture of the dicarboxylic acid material
and amine, while removing water. Other post-reaction processes
known in the art can also be applied.
[0099] Typically, the lubricating oil composition may contain from
1 to 20, such as 3 to 15, preferably 3 to 12, mass %
dispersant.
[0100] The ashless dispersant (D) of all aspects of the present
invention may comprise a mixture of ashless dispersant compounds.
In a preferred embodiment of all aspects of the present invention,
the lubricating oil composition comprises an ashless dispersant
made by the thermal "ene" process. If the lubricating oil
composition comprises a mixture of ashless dispersant additives, an
ashless dispersant made by the thermal "ene" process preferably
provides the majority of the ashless dispersant. For example, the
ashless dispersant (D) may comprise at least 50 mass/%, or at least
70% or at least 75% ashless dispersant made by the thermal process.
In an embodiment of all aspects of the present invention the
ashless dispersant (D) comprises only dispersant made by the
thermal process.
[0101] The amount of nitrogen in a lubricating oil composition
according to the present invention will depend upon the particular
application of the oil. Typically, a lubricating oil composition
according to the present invention contains at least 0.02, such as
at least 0.03 or 0.04 mass % nitrogen, based on the total mass of
the composition and as measured according to ASTM method D5291.
Suitably, the lubricating oil composition will contain no more than
0.20, such as no more than 0.15 or no more than 0.12 mass %
nitrogen based upon the total mass of the composition and as
measured according to ASTM D5291.
Metal-Containing Detergent (E)
[0102] Suitably the lubricating oil composition of all aspects of
the present invention further comprises at least one
metal-containing detergent additive.
[0103] Metal-containing detergents function both as detergents to
reduce or remove deposits and as acid neutralizers or rust
inhibitors, thereby reducing wear and corrosion and extending
engine life. Detergents generally comprise a polar head with a long
hydrophobic tail, with the polar head comprising a metal salt of an
acidic organic compound. The salts may contain a substantially
stoichiometric amount of the metal in which case they are usually
described as normal or neutral salts, and would typically have a
total base number or TBN (as can be measured by ASTM D2896) of from
0 to 80 mg KOH/g. A large amount of a metal base may be
incorporated by reacting excess metal compound (e.g., an oxide or
hydroxide) with an acidic gas (e.g., carbon dioxide). The resulting
overbased detergent comprises neutralized detergent as the outer
layer of a metal base (e.g. carbonate) micelle. Such overbased
detergents may have a TBN of 150 mg KOH/g or greater, and typically
will have a TBN of from 250 to 450 mg KOH/g or more. In the
presence of the compounds of Formula I, the amount of overbased
detergent can be reduced, or detergents having reduced levels of
overbasing (e.g., detergents having a TBN of 100 to 200 mg KOH/g),
or neutral detergents can be employed, resulting in a corresponding
reduction in the SASH content of the lubricating oil composition
without a reduction in the performance thereof.
[0104] Detergents that may be used include oil-soluble neutral and
overbased sulfonates, phenates, sulfurized phenates,
thiophosphonates, salicylates, and naphthenates and other
oil-soluble carboxylates of a metal, particularly the alkali or
alkaline earth metals, e.g., sodium, potassium, lithium, calcium,
and magnesium. The most commonly used metals are calcium and
magnesium, which may both be present in detergents used in a
lubricating oil composition according to any aspect of the present
invention. Combinations of detergents, whether overbased or neutral
or both, may be used.
[0105] Sulfonates may be prepared from sulfonic acids which are
typically obtained by the sulfonation of alkyl substituted aromatic
hydrocarbons such as those obtained from the fractionation of
petroleum or by the alkylation of aromatic hydrocarbons. Examples
included those obtained by alkylating benzene, toluene, xylene,
naphthalene, diphenyl or their halogen derivatives such as
chlorobenzene, chlorotoluene and chloronaphthalene. The alkylation
may be carried out in the presence of a catalyst with alkylating
agents having from about 3 to more than 70 carbon atoms. The
alkaryl sulfonates usually contain from about 9 to about 80 or more
carbon atoms, preferably from about 16 to about 60 carbon atoms per
alkyl substituted aromatic moiety. The oil soluble sulfonates or
alkaryl sulfonic acids may be neutralized with oxides, hydroxides,
alkoxides, carbonates, carboxylate, sulfides, hydrosulfides,
nitrates, borates and ethers of the metal. The amount of metal
compound is chosen having regard to the desired TBN of the final
product but typically ranges from about 100 to 220 mass %
(preferably at least 125 mass %) of that stoichiometrically
required.
[0106] Metal salts of phenols and sulfurized phenols are prepared
by reaction with an appropriate metal compound such as an oxide or
hydroxide and neutral or overbased products may be obtained by
methods well known in the art. Sulfurized phenols may be prepared
by reacting a phenol with sulfur or a sulfur containing compound
such as hydrogen sulfide, sulfur monohalide or sulfur dihalide, to
form products which are generally mixtures of compounds in which 2
or more phenols are bridged by sulfur containing bridges.
[0107] Carboxylate detergents, e.g., salicylates, can be prepared
by reacting an aromatic carboxylic acid with an appropriate metal
compound such as an oxide or hydroxide and neutral or overbased
products may be obtained by methods well known in the art. The
aromatic moiety of the aromatic carboxylic acid can contain
heteroatoms, such as nitrogen and oxygen. Preferably, the moiety
contains only carbon atoms; more preferably the moiety contains six
or more carbon atoms; for example benzene is a preferred moiety.
The aromatic carboxylic acid may contain one or more aromatic
moieties, such as one or more benzene rings, either fused or
connected via alkylene bridges.
[0108] Preferred substituents in oil-soluble salicylic acids are
alkyl substituents. In alkyl-substituted salicylic acids, the alkyl
groups advantageously contain 5 to 100, preferably 9 to 30,
especially 14 to 20, carbon atoms. Where there is more than one
alkyl group, the average number of carbon atoms in all of the alkyl
groups is preferably at least 9 to ensure adequate oil
solubility.
[0109] The metal-containing detergent (E) may comprise one of more
metal detergents that are neutral or overbased alkali or alkaline
earth metal salicylates. Highly preferred salicylate detergents
include alkaline earth metal salicylates, particularly magnesium
and calcium, especially, calcium salicylates. The metal salicylate
may be the sole metal-containing detergent present in the
lubricating oil composition of all aspects of the present
invention. Alternatively, other metal-containing detergents, such
as metal sulfonates or phenates, may be present in the lubricating
composition. Preferably, the salicylate detergent provides the
majority of the detergent additive in the lubricating oil
composition.
[0110] The total amount of metal-containing detergent additive
present in the lubricating oil composition according to any aspect
of the present invention is suitably in the range of 0.1-10 mass %,
preferably from 0.5 to 5 mass % on an active matter basis.
Co-Additives
[0111] Lubricating oil compositions according to each aspect of the
invention may additionally comprise one or more co-additives, which
are different from additive components (B), (C), (D) and (E).
Suitable co-additives and their common treat rates are discussed
below. All the values listed are stated as mass percent active
ingredient in a fully formulated lubricant.
TABLE-US-00002 Mass % Mass % Additive (Broad) (Preferred) Corrosion
Inhibitor 0-5 0-1.5 Metal Dihydrocarbyl Dithiophosphate 0-10 0-4
Anti-Oxidants 0-5 0.01-3.sup. Pour Point Depressant 0.01-5 0.01-1.5
Anti-Foaming Agent 0-5 0.001-0.15 Viscosity Modifier (1) 0-10
0.01-4.sup. Mineral or Synthetic Base Oil Balance Balance (1)
Viscosity modifiers are used only in multi-graded oils.
[0112] The final lubricating oil composition, typically made by
blending the or each additive into the base oil, may contain from 5
to 25, preferably 5 to 18, typically 7 to 15, mass % of the
additives; the remainder being oil of lubricating viscosity.
[0113] The above mentioned co-additives are discussed in further
detail as follows; as is known in the art, some additives can
provide a multiplicity of effects, for example, a single additive
may act as a dispersant and as an oxidation inhibitor.
[0114] Anti-wear agents reduce friction and excessive wear and are
usually based on compounds containing sulfur or phosphorous or
both, for example that are capable of depositing polysulfide films
on the surfaces involved. Noteworthy are dihydrocarbyl
dithiophosphate metal salts wherein the metal may be an alkali or
alkaline earth metal, or aluminium, lead, tin, molybdenum,
manganese, nickel, copper, or preferably, zinc.
[0115] Dihydrocarbyl dithiophosphate metal salts may be prepared in
accordance with known techniques by first forming a dihydrocarbyl
dithiophosphoric acid (DDPA), usually by reaction of one or more
alcohols or a phenol with P.sub.2S.sub.5 and then neutralizing the
formed DDPA with a metal compound. For example, a dithiophosphoric
acid may be made by reacting mixtures of primary and secondary
alcohols. Alternatively, multiple dithiophosphoric acids can be
prepared where the hydrocarbyl groups on one are entirely secondary
in character and the hydrocarbyl groups on the others are entirely
primary in character. To make the metal salt, any basic or neutral
metal compound could be used but the oxides, hydroxides and
carbonates are most generally employed. Commercial additives
frequently contain an excess of metal due to the use of an excess
of the basic metal compound in the neutralization reaction.
[0116] The preferred zinc dihydrocarbyl dithiophosphates (ZDDP) are
oil-soluble salts of dihydrocarbyl dithiophosphoric acids and may
be represented by the following formula:
##STR00004##
wherein R and R' may be the same or different hydrocarbyl radicals
containing from 1 to 18, preferably 2 to 12, carbon atoms and
including radicals such as alkyl, alkenyl, aryl, arylalkyl, alkaryl
and cycloaliphatic radicals. Particularly preferred as R and R'
groups are alkyl groups of 2 to 8 carbon atoms. Thus, the radicals
may, for example, be ethyl, n-propyl, i-propyl, n-butyl, i-butyl,
sec-butyl, amyl, n-hexyl, i-hexyl, n-octyl, decyl, dodecyl,
octadecyl, 2-ethylhexyl, phenyl, butylphenyl, cyclohexyl,
methylcyclopentyl, propenyl, butenyl. In order to obtain oil
solubility, the total number of carbon atoms (i.e. R and R') in the
dithiophosphoric acid will generally be about 5 or greater. The
zinc dihydrocarbyl dithiophosphate can therefore comprise zinc
dialkyl dithiophosphates.
[0117] The ZDDP is added to the lubricating oil compositions in
amounts sufficient to provide at least 800 ppm such as at least 900
ppm or at least 1000 ppm by mass of phosphorous to the lubricating
oil, based upon the total mass of the lubricating oil composition,
and as measured in accordance with ASTM D5185.
[0118] The ZDDP is suitably added to the lubricating oil
compositions in amounts sufficient to provide no more than 1200 ppm
by mass of phosphorous to the lubricating oil, based upon the total
mass of the lubricating oil composition, and as measured in
accordance with ASTM D5185.
[0119] Viscosity modifiers (VM) function to impart high and low
temperature operability to a lubricating oil. The VM used may have
that sole function, or may be multifunctional. Multifunctional
viscosity modifiers that also function as dispersants are also
known. Suitable viscosity modifiers are polyisobutylene, copolymers
of ethylene and propylene and higher alpha-olefins,
polymethacrylates, polyalkylmethacrylates, methacrylate copolymers,
copolymers of an unsaturated dicarboxylic acid and a vinyl
compound, inter polymers of styrene and acrylic esters, and
partially hydrogenated copolymers of styrene/isoprene,
styrene/butadiene, and isoprene/butadiene, as well as the partially
hydrogenated homopolymers of butadiene and isoprene and
isoprene/divinylbenzene. Preferred viscosity modifiers for all
aspects of the present invention are copolymers of an unsaturated
dicarboxylic acid and a vinyl compound, inter polymers of styrene
and acrylic esters, and, most preferably, partially hydrogenated
copolymers of styrene/isoprene, styrene/butadiene, and
isoprene/butadiene, as well as the partially hydrogenated
homopolymers of butadiene and isoprene and isoprene/divinylbenzene.
The preferred partially hydrogenated copolymers of
styrene/isoprene, styrene/butadiene, and isoprene/butadiene, may be
random copolymers but are preferably block copolymers. The
preferred, partially hydrogenated copolymers of styrene/isoprene,
styrene/butadiene, and isoprene/butadiene, and partially
hydrogenated homopolymers of butadiene and isoprene and
isoprene/divinylbenzene viscosity modifiers may be linear polymers
or star (radial) polymers.
[0120] Linear block copolymers useful in the practice of the
present invention may be represented by the following general
formula:
A.sub.x-(B-A).sub.y-B.sub.x
wherein: A is a polymeric block comprising predominantly
monoalkenyl aromatic hydrocarbon monomer units; B is a polymeric
block comprising predominantly conjugated diolefin monomer units; x
and z are, independently, a number equal to 0 or 1; and y is a
whole number ranging from 1 to about 15.
[0121] Useful tapered linear block copolymers may be represented by
the following general formula:
A-A/B--B
wherein: A is a polymeric block comprising predominantly
monoalkenyl aromatic hydrocarbon monomer units; B is a polymeric
block comprising predominantly conjugated diolefin monomer units;
and A/B is a tapered segment containing both monoalkenyl aromatic
hydrocarbon and conjugated diolefin units.
[0122] Star or radial homopolymers or random copolymers of diene(s)
(e.g., isoprene and/or butadiene) may be represented, generally, by
the following general formula:
(B).sub.n--C
wherein: B and C are as previously defined; and n is a number from
3 to 30; C is the core of the radial polymer formed with a
polyfunctional coupling agent; B' is a polymeric block comprising
predominantly conjugated diolefin units, which B' may be the same
or different from B; and n' and n'' are integers representing the
number of each type of arm and the sum of n' and n'' will be a
number from 3 to 30.
[0123] Star or radial block copolymers may be represented,
generally, by the following general formula:
(B.sub.x-(A-B).sub.y-A.sub.z).sub.n-C; and
(B'.sub.x-(A-B).sub.y-A.sub.z).sub.n'-C(B').sub.n''
wherein: A, B, x, y and z are as previously defined; n is a number
from 3 to 30; C is the core of the radial polymer formed with a
polyfunctional coupling agent; B' is a polymeric block comprising
predominantly conjugated diolefin units, which B' may be the same
or different from B; and n' and n'' are integers representing the
number of each type of arm and the sum of n' and n'' will be a
number from 3 to 30.
[0124] As used herein in connection with polymer block composition,
the term "predominantly" means that the specified monomer or
monomer type which is the principle component in that polymer block
is present in an amount of at least 85% by weight of the block.
[0125] Suitably, the lubricating oil composition according to all
aspects of the present invention comprises one or more star polymer
viscosity modifier. The lubricating oil composition according to
all aspects of the present invention may comprise a mixture of
linear and star polymer viscosity modifiers. In a preferred
embodiment, the lubricating oil composition according to all
aspects of the present invention comprises only star polymer
viscosity modifier(s).
[0126] Oil-soluble viscosity modifying polymers generally have
weight average molecular weights of from 10,000 to 1,000,000,
preferably 20,000 to 500,000, which may be determined by gel
permeation chromatography or by light scattering.
[0127] Anti-oxidants, sometimes referred to as oxidation
inhibitors, increase the resistance of the composition to oxidation
and may work by combining with and modifying peroxides to render
them harmless, by decomposing peroxides, or by rendering oxidation
catalysts inert. Oxidative deterioration can be evidenced by sludge
in the lubricant, varnish-like deposits on the metal surfaces, and
by viscosity growth.
[0128] Examples of suitable antioxidants are selected from
copper-containing antioxidants, sulfur-containing antioxidants,
aromatic amine-containing antioxidants, hindered phenolic
antioxidants and dithiophosphates derivative. Preferred
anti-oxidants ashless antioxidants. Preferred ashless antioxidants
are ashless aromatic amine-containing antioxidants, ashless
hindered phenolic antioxidants and mixtures thereof. In a preferred
embodiment, one or more antioxidant is present in a lubricating oil
composition of all aspects of the present invention.
[0129] Rust inhibitors selected from the group consisting of
nonionic polyoxyalkylene polyols and esters thereof,
polyoxyalkylene phenols, and anionic alkyl sulfonic acids may be
used.
[0130] Copper and lead bearing corrosion inhibitors may be used in
some embodiments of the invention, and when these compounds are
included in the lubricating composition, they are preferably
present in an amount not exceeding 0.2 wt. % active ingredient.
However, in a preferred embodiment of the present invention, no
copper-containing additives are present in the lubricating oil
composition. When present, suitable such compounds are the
thiadiazole polysulfides containing from 5 to 50 carbon atoms,
their derivatives and polymers thereof. Derivatives of 1, 3, 4
thiadiazoles such as those described in U.S. Pat. Nos. 2,719,125;
2,719,126; and 3,087,932; are typical. Other similar materials are
described in U.S. Pat. Nos. 3,821,236; 3,904,537; 4,097,387;
4,107,059; 4,136,043; 4,188,299; and 4,193,882. Other additives are
the thio and polythio sulfenamides of thiadiazoles such as those
described in UK Patent Specification No. 1,560,830. Benzotriazoles
derivatives also fall within this class of additives.
[0131] A small amount of a demulsifying component may be used. A
preferred demulsifying component is described in EP 330522. It is
obtained by reacting an alkylene oxide with an adduct obtained by
reacting a bis-epoxide with a polyhydric alcohol. The demulsifier
should be used at a level not exceeding 0.1 mass % active
ingredient. A treat rate of 0.001 to 0.05 mass % active ingredient
is convenient.
[0132] Pour point depressants, otherwise known as lube oil flow
improvers, lower the minimum temperature at which the fluid will
flow or can be poured. Such additives are well known. Typical of
those additives which improve the low temperature fluidity of the
fluid are C.sub.8 to C.sub.18 dialkyl fumarate/vinyl acetate
copolymers, polyalkylmethacrylates and the like.
[0133] Foam control can be provided by many compounds including an
antifoamant of the polysiloxane type, for example, silicone oil or
polydimethyl siloxane.
[0134] The individual additives may be incorporated into a base
stock in any convenient way. Thus, each of the components can be
added directly to the base stock or base oil blend by dispersing or
dissolving it in the base stock or base oil blend at the desired
level of concentration. Such blending may occur at ambient or
elevated temperatures.
[0135] Preferably, all the additives except for the viscosity
modifier and the pour point depressant are blended into a
concentrate or additive package described herein as the additive
package that is subsequently blended into base stock to make the
finished lubricant. The concentrate will typically be formulated to
contain the additive(s) in proper amounts to provide the desired
concentration in the final formulation when the concentrate is
combined with a predetermined amount of a base lubricant.
[0136] The concentrate is preferably made in accordance with the
method described in U.S. Pat. No. 4,938,880. That patent describes
making a pre-mix of ashless dispersant and metal detergents that is
pre-blended at a temperature of at least about 100.degree. C.
Thereafter, the pre-mix is cooled to at least 85.degree. C. and the
additional components are added.
[0137] The final crankcase lubricating oil formulation may employ
from 2 to 20, preferably 4 to 18, and most preferably 5 to 17, mass
% of the concentrate or additive package with the remainder being
base stock.
[0138] The lubricating oil composition of the present invention may
have a sulphated ash content of less than or equal to 1.2,
preferably less than or equal to 1.1, more preferably less than or
equal to 1.0, mass % (ASTM D874) based on the total mass of the
composition. The lubricating oil composition of the present
invention suitably has a sulphated ash content of at least 0.4,
preferably at least 0.5, such as at least 0.6 mass % (ASTM D874)
based on the total mass of the composition. Suitably the sulphated
ash content of the lubricating oil composition is in the range of
0.04-1.2 mass %, preferably in the range of 0.06 to 1.0 mass %
(ASTM D874).
[0139] The amount of sulfur in the lubricating oil composition will
depend upon the particular application of the lubricating oil
composition. The lubricating oil composition may contain sulphur in
an amount of up to 0.4, such as, up to 0.35 mass % sulphur (ASTM
D2622) based on the total mass of the composition. Generally the
lubricating oil composition will contain at least 0.1, or even at
least 0.2 mass % sulphur (ASTM D2622) based on the total mass of
the composition.
[0140] Suitably, the lubricating oil composition of all aspects and
embodiments of the present invention may have a total base number
(TBN), as measured in accordance with ASTM D2896, of 4 to 15,
preferably 4 to 10 mg KOH/g.
EXAMPLES
[0141] The invention will now be described in the following
examples which are not intended to limit the scope of the claims
hereof.
[0142] A series of 10W-30 oils as set out in Table 1 were blended.
These oils were subjected to a variety of testing, as set out in
Examples 1 and 2 below. The test methods used are described
here.
[0143] The High Frequency Reciprocating Rig (HFRR--supplied by PCS
Instruments) to evaluate the boundary regime friction
characteristics of the oils.
[0144] The rig was set up with a 6 mm ball on a 10 mm disc. The
test protocol employed was as follows:
TABLE-US-00003 Test Duration (mins) 1 min hold and 5 min run at
each temperature stage Test Load (N) 4 Frequency (Hz) 40 Stroke
Length (microns) 1,000 Temperature (.degree. C.) 40, 60, 80, 100,
120, 140 (low temperature stage) 160, 180, 200, 220 (high
temperature stage)
[0145] The test has 6 stages in the low temperature runs and 4
stages in the high temperature runs. The average friction at each
temperature stage is measured and the overall average friction
across all stages.
[0146] The JASO T 903:2016 clutch friction test measures clutch
friction based on the SAE #2 test rig. The test runs at 3600 rpm
and duration of 1000 cycles of engagement and disengagement of the
friction test plates. The friction coefficient of the test oil is
measured in the test cycles. The test generates three different
friction indices namely the Static Friction Index (SFI), Dynamic
Friction Index (DFI) and Stop Time Index (SFI). These indices are
calculated based on the friction coefficients of the test oil
against two standard reference oils. These three indices will
determine the classification of the JASO friction performance to
MA2, MA1, MA or MB based on the limits specified in the JASO T
903:2016 specification. The limits for each classification are set
out below:
TABLE-US-00004 MB MA MA1 MA2 DFI .gtoreq.0.40 .gtoreq.1.35
.gtoreq.1.35 .gtoreq.1.50 and <1.35 and <2.5 and <1.50 and
<2.5 SFI .gtoreq.0.40 .gtoreq.1.45 .gtoreq.1.45 .gtoreq.1.60 and
<1.45 and <2.5 and <1.60 and <2.5 STI .gtoreq.0.40
.gtoreq.1.40 .gtoreq.1.40 .gtoreq.1.60 and <1.40 and <2.5 and
<1.60 and <2.5
[0147] The mini traction machine (MTM) supplied by PCS Instruments,
is a computer controlled traction and wear measurement instrument
which provides controlled traction mapping of fluids. It measures
the friction coefficient between a rotating bell on a rotating disk
at variable entrainment speed. Contact was formed between % inch
bell mounted on a pivoting shaft, which is automatically loaded
against a rotating 46 mm diameter disc horizontally mounted in the
test fluid reservoir. Variation of the entrainment speed simulates
variation in the thickness of the lubricating oil film between the
surfaces. As the MTM does not incorporate reciprocating motion, it
generally correlates with the mixed and hydrodynamic lubrication
regimes that are typical in bearings, pump and piston rings. The
test was run at four temperatures, 60.degree. C., 80.degree. C.,
100.degree. C. and 145.degree. C.
[0148] The Schwingung Reibung Verschleiss "SRV", supplied by
Optimol, is used to evaluate friction and wear properties of liquid
lubricants across a broad range of applications. There are
different specimens and configurations that can be used in SRV; in
these examples the rig was set up with a 15.times.22 mm cylinder on
a 24.times.7.9 mm disk. The test has 6 temperature stages and you
can record the average friction at each temperature stage and the
overall average friction across all stages. The test protocol
employed was as follows:
TABLE-US-00005 Test Duration (mins) 1 min hold and 5 min run at
each temperature stage Test Load (N) 400 Frequency (Hz) 50 Stroke
Length (microns) 3,000 Temperature (.degree. C.) 60, 80, 100, 120,
140, 160
[0149] The test oil forms a film in between the cylinder and disk,
the cylinder is engaged in a sliding or reciprocating stroke across
the disk and friction between the metal-metal contact is measured.
This is used to evaluate the boundary regime friction
characteristics of the oils.
TABLE-US-00006 TABLE 1 Additive Oil 1 Oil 2 Oil 3 Oil 4 Oil 5 Oil 6
Oil 7 Oil 8 Oil 9 Additive Package.sup.1 7.09 7.09 7.09 7.09 7.09
7.09 7.09 7.09 7.09.sup.6 Molybdenum Dithiocarbamate.sup.2 0.23
0.11 0.11 0.045 0.045 Ashless Friction Modifier 1.sup.3 0.25
Ashless Friction Modifier 2.sup.4 0.5 0.25 Ashless Friction
Modifier 3.sup.5 0.5 Viscosity modifier 4.5 4.5 4.5 4.5 4.5 4.5 4.5
4.5 4.5 Group II base oil Balance Balance Balance Balance Balance
Balance Balance Balance Balance SASII, mass % 0.820 0.820 0.820
0.820 0.820 0.820 0.820 0.820 0.820 (ASTM D374) P, mass % 0.093
0.093 0.093 0.093 0.093 0.093 0.093 0.093 0.093 (ASTM D5185) B, ppm
(ASTM D5185) 100 100 100 100 100 100 100 100 100 Mo, ppm (ASTM
D5185) 0 275 0 0 0 137 137 55 55 TBN (ASTM D2896) 6.63 6.73 7.07
6.63 6.63 6.68 6.90 6.65 6.61 N, mass % (ASTM D5291) 0.064 0.069
0.075 0.064 0.064 0.066 0.072 0.065 0.065 Ca, mass % (ASTM D5185)
0.184 0.184 0.184 0.184 0.184 0.184 0.184 0.184 0.184 S, mass %
(ASTM D2622) 0.249 0.299 0.249 0.249 0.249 0.274 0.274 0.259 0.259
.sup.1The additive package had the same composition for all oils in
Table I and comprised a dispersant combination comprising
non-borated and borated polyisobutonyl succinimide dispersant, a
calcium sulphonate dertergent, a combination of hindered phenol and
aromatic amine antioxidants, zine dialkyldithiophosphate, silicone
antiform, pour point depressant and dilvent oil. .sup.2The
molybdenum dithiocarbamate was a trimeric molybdenum
dithiocarbamate additive available from Infineum UK Limited a
Infineum C9455B. .sup.3Ashless friction modifier 1 was glycerol
monooleate. .sup.4Ashless friction modifier 2 was a tallow ester of
triethanol amine. .sup.5Ashless friction modifier 3 was
octadecylsuccinic anhydride. .sup.6The "chloro" non-borated
dispersant in the additive package of Oils 1-8 was replaced in the
additive package of Oil 9 by "thermal" non-borated dispersant, at
equivalent nitrogen content. The viscosity modifier was a
hydrogenated styrene-dicne star polymer indicates data missing or
illegible when filed
Example 1
[0150] Each of Oils 1-7 were tested in the HFRR and the average
coefficient at each different temperature is set out in Table 2
below:
TABLE-US-00007 TABLE 2 Temperature, .degree. C. Oil 1 Oil 2 Oil 3
Oil 4 Oil 5 Oil 6 Oil 7 40 0.122 0.117 0.120 0.117 0.123 0.119
0.122 60 0.135 0.124 0.132 0.125 0.136 0.125 0.138 80 0.153 0.128
0.146 0.132 0.144 0.144 0.148 100 0.158 0.113 0.150 0.138 0.148
0.136 0.127 120 0.161 0.122 0.154 0.145 0.154 0.135 0.115 140 0.162
0.122 0.157 0.149 0.155 0.131 0.118 160 0.162 0.096 0.140 0.140
0.136 0.125 0.090 180 0.159 0.099 0.138 0.141 0.134 0.130 0.063 200
0.158 0.100 0.136 0.139 0.140 0.126 0.064 220 0.156 0.095 0.141
0.145 0.144 0.124 0.078
[0151] This data is also graphically represented in FIG. 1.
[0152] Each of Oils 1-7 were also tested in the SRV and the average
coefficient at each different temperature is set out in Table 3
below:
TABLE-US-00008 TABLE 3 Temperature, .degree. C. Oil 1 Oil 2 Oil 3
Oil 4 Oil 5 Oil 6 Oil 7 60 0.170 0.082 0.161 0.162 0.160 0.134
0.135 80 0.165 0.090 0.161 0.163 0.160 0.147 0.152 100 0.167 0.125
0.162 0.165 0.161 0.149 0.154 120 0.171 0.135 0.161 0.167 0.164
0.151 0.153 140 0.173 0.127 0.161 0.166 0.167 0.151 0.150 160 0.171
0.111 0.167 0.164 0.169 0.147 0.135
[0153] This data is also graphically represented in FIG. 2
[0154] It can be seen from the data that as expected the oil with
0.23 mass % molybdenum dithiocarbamate has generally the lowest
coefficient of friction and this reduces as the temperature
increases. Halving the amount of molybdenum dithiocarbamate in Oil
6 increases the friction coefficient at higher temperature. Oils 3,
4 and 5 with ashless friction modifier and no molybdenum compound
generally have a higher friction coefficient than the
molybdenum-containing oils, though still perform better than the
reference Oil 1, which contains neither ashless friction modifier
nor molybdenum compound. It is noted that Oil 7, which contains
half the amount of molybdenum dithiocarbamate and half the amount
of ashless friction modifier 2 also performs well compared with Oil
2 with the higher molybdenum content.
[0155] Oils 6, 7 and 8 were tested in the JASO T 903:2016. Oil 8,
which comprises a lower content of molybdenum achieved an MA2
rating, which is the highest friction level that can be achieved in
this test and is desirable for good clutch operation. Oil 6, which
has a higher molybdenum content achieved only an MB rating, which
is the lowest rating in this test and not desirable for good
functioning of a clutch assembly. These results are to be expected,
since it is known that molybdenum compounds, especially molybdenum
dithiocarbamates, are effective friction modifiers and at higher
treat rates provide too much friction reduction for acceptable
functioning of a clutch assembly.
[0156] Oil 7 though, which comprises the same higher molybdenum
content as Oil 6, but additionally contains ashless friction
modifier, achieves an MA1 rating. This is a good operational rating
for a clutch assembly.
[0157] It can be seen from these results that use of the ashless
friction modifier in combination with the molybdenum additive
allows the use of higher treat rates of the molybdenum additive,
which is beneficial for the engine lubrication, whilst still
maintaining a clutch friction that is acceptable in use.
[0158] Thus, it can be seen from both the HFRR, SRV data and the
JASO T 903:2016 data, that a combination of oil-soluble molybdenum
compound and ashless organic friction modifier can be used in a
lubricating oil composition provided to lubricate the engine
crankcase and the clutch assembly from a common sump and provide a
good coefficient of friction in the engine whilst maintaining
acceptable friction in the clutch assembly.
Example 2
[0159] Oils 8 and 9, which differed only in the type of non-borated
dispersant, were tested in the MTM. FIGS. 3-6 show that Oil 9 with
the "thermal" dispersant in place of the "chloro" dispersant
exhibits reduced friction coefficient, which reduction is
particularly marked at higher temperature.
Example 3
[0160] Three further oils, Oils 9-11, were blended and tested in
the HFRR. SRV and JASO T 903:2016. The oils were compared to a
commercial 10W-30 oil, composition unknown, which oil was measured
as having an MA2 qualification in the JASO T 903:2016.
[0161] The composition of Oils 9-11 is set out in Table 4 below,
the amounts being mass % active matter.
TABLE-US-00009 TABLE 4 Additive Oil 9 Oil 10 Oil 11 Additive
Package.sup.8 7.9 7.9 7.9 Ashless Friction Modifier 2.sup.4 0.2 0.2
0.2 Molybdenum Dithiocarbamate.sup.2 0.045 0.045 0.045 Viscosity
Modifier.sup.7 11 9.5 15.3 Group II base oil Balance Group III base
oil Balance Balance SAE Viscosity Grade 5W-30 10W-30 10W-40 SASH,
mass %, (ASTM D874) 0.688 0.688 0.688 P, ppm (ASTM D5185) 0.086
0.086 0.086 Mo, ppm (ASTM D5185) 55 55 55 S, mass % (ASTM D2622)
0.198 0.198 0.198 N, mass % (ASTM D5291) 0.08 0.08 0.08 B, ppm
(ASTM D5185) 86 86 86 Ca, mass % (ASTM D5185) 0.148 0.148 0.148
TBN, (ASTM D2896) 6.59 6.59 6.59 .sup.8The additive package was the
same for each of Oils 9 to 11 and contained a combination of
borated and non-borated polyisobutenylsuccinimide dispersants,
calcium salicylate detergent, ZDDP, aromatic amine and hindered
phenol antioxidant, silicone antifoam PPD and diluent oil.
.sup.2The molybdenum dithiocarbamate was a trimeric molybdenum
dithiocarbamate additive available from Infineum UK Limited as
Infineum C9455B. .sup.4Ashless friction modifier 2 was a tallow
ester of triethanol amine. .sup.7The viscosity modifier was a
hydrogenated styrene-diene star polymer.
[0162] Oils 9 to 11 vary only in the amount of viscosity modifier
and the base oil, in order to obtain the different SAE viscosity
grades indicated.
[0163] The reference oil and each of Oils 9-11 where tested in the
HFRR and the average coefficient at each different temperature is
set out in Table 5 below:
TABLE-US-00010 TABLE 5 Temp (.degree. C.) Reference Oil 9 Oil 10
Oil 11 40 0.126 0.115 0.112 0.116 60 0.1335 0.124 0.119 0.125 80
0.154 0.143 0.138 0.144 100 0.1635 0.143 0.1395 0.1465 120 0.165
0.129 0.1305 0.139 140 0.166 0.101 0.0975 0.1335 160 0.157 0.148
0.150 0.147 180 0.158 0.133 0.136 0.144 200 0.157 0.091 0.093 0.097
220 0.160 0.086 0.089 0.089
[0164] The results are also represented graphically below, in FIG.
7.
[0165] The reference oil and each of Oils 9-11 where tested in the
SRV and the average coefficient at each different temperature is
set out in Table 6 below:
TABLE-US-00011 TABLE 6 Temp (.degree. C.) Reference Oil 9 Oil 10
Oil 11 60 0.164 0.160 0.160 0.159 80 0.159 0.156 0.156 0.154 100
0.163 0.158 0.158 0.157 120 0.168 0.160 0.160 0.159 140 0.172 0.158
0.159 0.159 160 0.174 0.148 0.147 0.152
[0166] The results are also represented graphically below, in FIG.
8.
[0167] It can be seen from the SRV data, that all of Oil 9-11
exhibited improved friction performance in the SRV compared to the
commercial reference oil.
[0168] Oil 10 was also tested in the JASO T 903:2016 clutch
friction test and found to have a MA2 performance level. Thus, Oil
10 exhibits comparable clutch friction performance to the
commercial reference oil, but improved engine friction performance
in the SRV.
* * * * *