U.S. patent application number 14/727923 was filed with the patent office on 2015-12-03 for lubricating oil compositions.
This patent application is currently assigned to Infineum International Limited. The applicant listed for this patent is Infineum International Limited. Invention is credited to Anthony J. Strong, Philip J. Woodward.
Application Number | 20150344812 14/727923 |
Document ID | / |
Family ID | 50828820 |
Filed Date | 2015-12-03 |
United States Patent
Application |
20150344812 |
Kind Code |
A1 |
Strong; Anthony J. ; et
al. |
December 3, 2015 |
LUBRICATING OIL COMPOSITIONS
Abstract
A lubricating oil composition having a sulphated ash content of
less than or equal to 1.2 mass % as determined by ASTM D874 and a
phosphorous content of less than or equal to 0.12 mass % as
determined by ASTM D5185, which lubricating oil composition
comprises or is made by admixing: an oil of lubricating viscosity,
in a major amount; an oil-soluble or oil-dispersible polymeric
friction modifier as an additive in an effective minor amount; and,
an oil-soluble or oil-dispersible dihydrocarbyl dithiophosphate
metal salt as an additive in an effective minor amount.
Inventors: |
Strong; Anthony J.; (Oxford,
GB) ; Woodward; Philip J.; (Reading, GB) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Infineum International Limited |
Abingdon |
|
GB |
|
|
Assignee: |
Infineum International
Limited
Abingdon
GB
|
Family ID: |
50828820 |
Appl. No.: |
14/727923 |
Filed: |
June 2, 2015 |
Current U.S.
Class: |
508/306 |
Current CPC
Class: |
C10N 2040/252 20200501;
C10N 2010/04 20130101; C10N 2040/28 20130101; C10N 2030/06
20130101; C10M 161/00 20130101; C10N 2030/12 20130101; C10M
2209/111 20130101; C10M 2203/1006 20130101; C10M 2223/045 20130101;
C10N 2030/45 20200501; C10N 2030/42 20200501 |
International
Class: |
C10M 161/00 20060101
C10M161/00 |
Foreign Application Data
Date |
Code |
Application Number |
Jun 2, 2014 |
EP |
14170782.8 |
Claims
1. A lubricating oil composition having a sulphated ash content of
less than or equal to 1.2 mass % as determined by ASTM D874 and a
phosphorous content of less than or equal to 0.12 mass % as
determined by ASTM D5185, which lubricating oil composition
comprises or is made by admixing: (A) an oil of lubricating
viscosity, in a major amount; (B) an oil-soluble or oil-dispersible
polymeric friction modifier as an additive in an effective minor
amount, the polymeric friction modifier being the reaction product
of solely: (i) a functionalised polyolefin; (ii) a polyalkylene
glycol; (iii) a polyol; and, (iv) a polycarboxylic acid; and, (C)
at least one oil-soluble or oil-dispersible dihydrocarbyl
dithiophosphate metal salt as an additive in an effective minor
amount.
2. A composition as claimed in claim 1, wherein the functionalised
polyolefin (B (i)) is a functionalised polyisobutylene.
3. A composition as claimed in claim 1, wherein the functionalised
polyolefin (B (i)) is functionalised with a diacid or anhydride
functional group.
4. A composition as claimed in claim 2, wherein the functionalised
polyolefin (B (i)) is functionalised with a diacid or anhydride
functional group.
5. A composition as claimed in claim 3, wherein the functionalised
polyolefin (B (i)) is functionalised with a succinic anhydride
functional group.
6. A composition as claimed in claim 4, wherein the functionalised
polyolefin (B (i)) is functionalised with a succinic anhydride
functional group.
7. A composition as claimed in claim 1, wherein the functionalised
polyolefin (B (i)) is polyisobutylene succinic anhydride
(PIBSA).
8. A composition as claimed in claim 1, wherein the polyalkylene
glycol is a poly(C.sub.2 to C.sub.6 alkylene) glycol.
9. A composition as claimed in claim 8, wherein the polyalkylene
glycol is polyethylene glycol (PEG).
10. A composition as claimed in claim 1, wherein the polyol is a
C.sub.2 to C.sub.20 aliphatic hydrocarbyl polyol.
11. A composition as claimed in claim 10, wherein the C.sub.2 to
C.sub.20 aliphatic hydrocarbyl polyol is glycerol.
12. A composition as claimed in claim 1, wherein the polycarboxylic
acid is a C.sub.2 to C.sub.20 aliphatic hydrocarbyl dicarboxylic
acid.
13. The composition as claimed in claim 12, wherein the C.sub.2 to
C.sub.20 aliphatic hydrocarbyl dicarboxylic acid is sebacic
acid.
14. The composition as claimed in claim 1, wherein the oil-soluble
or oil-dispersible dihydrocarbyl dithiophosphate metal salt is a
zinc dihydrocarbyl dithiophosphate.
15. A method of lubricating a spark-ignited or compression-ignited
internal combustion engine comprising lubricating the engine with a
lubricating oil composition as claimed in claim 1.
Description
FIELD OF THE INVENTION
[0001] The present invention relates to automotive lubricating oil
compositions. More specifically, although not exclusively, the
present invention relates to automotive crankcase lubricating oil
compositions for use in gasoline (spark-ignited) and diesel
(compression-ignited) internal combustion engines, such
compositions being referred to as crankcase lubricants; and to the
use of additives in such lubricating oil compositions for improving
the anti-corrosion performance properties in respect of the
non-ferrous metallic engine components (i.e. suppressing the
corrosion of the non-ferrous metallic engine components),
particularly the engine components containing copper and/or lead
(e.g. bearings).
BACKGROUND OF THE INVENTION
[0002] A crankcase lubricant is an oil used for general lubrication
in an internal combustion engine where an oil sump is situated
generally below the crankshaft of the engine and to which
circulated oil returns.
[0003] Anti-wear agents are typically used as additives in a
crankcase lubricant to reduce excessive wear of the metallic engine
components. Such anti-wear agents are usually based on compounds
containing sulphur or phosphorus or both, for example compounds
that are capable of depositing polysulfide films on the surfaces of
the metallic engine components. Common anti-wear agents which are
routinely employed in a crankcase lubricant are dihydrocarbyl
dithiophosphate metal salts.
[0004] It is also desirable to reduce the energy and fuel
consumption requirements of the engine and there is, therefore,
also a need for crankcase lubricants which reduce the overall
friction of the engine. Reducing friction losses in an engine
typically contributes significantly to improving fuel economy
performance and fuel economy retention properties of the engine.
Accordingly, it has long been known to use ashless organic friction
modifiers, for example ashless nitrogen-free organic friction
modifiers (e.g. esters formed from carboxylic acids and alkanols,
such as glycerol monooleate (GMO)), as additives in a crankcase
lubricant to obtain improved friction properties and improved fuel
economy performance.
[0005] Accordingly, in order to provide a crankcase lubricant
having the desired anti-wear performance and the desired friction
properties, lubricating oil formulators have typically employed a
dihydrocarbyl dithiophosphate metal salt anti-wear additive in
combination with an ashless organic friction modifier additive,
such as GMO, in the lubricating oil composition.
[0006] It has now been found that the use of an ashless organic
friction modifier additive, such as GMO, in the lubricant typically
produces a significant amount of lead and copper corrosion.
Moreover, when the ashless organic friction modifier additive, such
as GMO, is used in combination with a dihydrocarbyl dithiophosphate
metal salt anti-wear additive the amount of lead corrosion
typically further increases. The corrosive nature of the ashless
organic friction modifier additive, such as GMO, and the increase
in lead corrosion attributable to the combination of the ashless
organic friction modifier additive and the dihydrocarbyl
dithiophosphate metal salt presents problems for the lubricant oil
formulator. For example, the corrosive nature of the additive
components, particularly when used in combination, may necessitate
reduced treat rates of the additive(s) thereby impacting on the
anti-wear performance and/or fuel economy performance of the
lubricant; alternatively, or additionally, it may be necessary to
include further relatively expensive anti-corrosion additives in
the lubricant to counteract the corrosive nature of the
dihydrocarbyl dithiophosphate metal salts and ashless organic
friction modifier additives.
[0007] Accordingly, there is a need for lubricating oil
compositions that include dihydrocarbyl dithiophosphate metal salt
anti-wear agents and ashless organic friction modifier additives
which exhibit improved anti-corrosion performance properties in
respect of the non-ferrous metallic engine components, particularly
those components which contain copper and/or lead, or alloys
thereof.
SUMMARY OF THE INVENTION
[0008] In accordance with a first aspect, the present invention
provides a lubricating oil composition having a sulphated ash
content of less than or equal to 1.2 mass % as determined by ASTM
D874 and a phosphorous content of less than or equal to 0.12 mass %
as determined by ASTM D5185, which lubricating oil composition
comprises or is made by admixing: [0009] (A) an oil of lubricating
viscosity, in a major amount; [0010] (B) an oil-soluble or
oil-dispersible polymeric friction modifier as an additive in an
effective minor amount, the polymeric friction modifier being the
reaction product of solely: [0011] (i) a functionalised polyolefin;
[0012] (ii) a polyalkylene glycol; [0013] (iii) a polyol; and,
[0014] (iv) a polycarboxylic acid [0015] and, [0016] (C) at least
one oil-soluble or oil-dispersible dihydrocarbyl dithiophosphate
metal salt as an additive in an effective minor amount.
[0017] Preferably, the lubricating oil composition of the present
invention is a crankcase lubricant.
[0018] Unexpectedly, it has been found that the use of the
polymeric friction modifier (B), as defined in accordance with the
first aspect of the invention, as an additive in an effective minor
amount in a lubricating oil composition comprising an oil of
lubricating viscosity in a major amount, may suppress the corrosion
of the non-ferrous metal (e.g. copper and/or lead) containing
engine components compared with a comparable lubricant which does
not include the polymeric friction modifier (B). In other words,
the polymeric friction modifier (B) may function as an
anti-corrosion agent in respect of the non-ferrous metal containing
engine components, especially the engine components which include
copper and/or lead, or an alloy containing such metals.
[0019] Furthermore, it has also been found that the use of the
oil-soluble or oil-dispersible polymeric friction modifier (B) as
defined in the first aspect of the present invention, as an
additive in an effective minor amount, in combination with the
oil-soluble or oil-dispersible dihydrocarbyl dithiophosphate metal
salt as defined in the first aspect of the present invention, as an
additive in an effective minor amount, in a lubricating oil
composition comprising an oil of lubricating viscosity in a major
amount, typically provides a lubricant that exhibits an improved
inhibition and/or reduction in the corrosion (i.e. suppresses the
corrosion) of the non-ferrous metal (e.g. copper and/or lead)
containing engine components compared with a comparable lubricant
which includes an ashless organic friction modifier, such as GMO,
in combination with an oil-soluble or oil-dispersible dihydrocarbyl
dithiophosphate metal salt as defined in the first aspect of the
present invention.
[0020] Still further, it has been found that the use of the
oil-soluble or oil-dispersible polymeric friction modifier (B) as
defined in the first aspect of the present invention, as an
additive in an effective minor amount, in combination with the
oil-soluble or oil-dispersible dihydrocarbyl dithiophosphate metal
salt as defined in the first aspect of the present invention, as an
additive in an effective minor amount, in a lubricating oil
composition comprising an oil of lubricating viscosity in a major
amount, typically provides a lubricant that exhibits an improved
inhibition and/or reduction in the corrosion (i.e. suppresses the
corrosion) of the copper containing metallic engine components
compared with: (i) a comparable lubricant which includes the
dihydrocarbyl dithiophosphate metal salt but not the polymeric
friction modifier; and, (ii) a comparable lubricant which does not
include both the dihydrocarbyl dithiophosphate metal salt and the
polymeric friction modifier.
[0021] Accordingly, such reduced levels of non-ferrous metal
corrosion (e.g. reduced levels of copper and/or lead corrosion)
associated with the use of the polymeric friction modifier (B)
compared with an ashless organic friction modifier such as GMO,
particularly when used in combination with a dihydrocarbyl
dithiophosphate metal salt, may permit increased treat rates of the
combination of such additives in a lubricant. Additionally, or
alternatively, such reduced levels of non-ferrous metal corrosion
may reduce the need for the use of relatively expensive
supplemental anti-corrosion additives. Accordingly, the use of the
polymeric friction modifier (B) in combination with a dihydrocarbyl
dithiophosphate metal salt typically provides the formulator with a
higher degree of flexibility when formulating lubricating oil
compositions which must meet strict anti-wear performance and fuel
economy performance criteria as specified in industry lubricating
oil specifications and in original equipment manufacturer's
specifications.
[0022] In accordance with a second aspect, the present invention
provides a method of lubricating a spark-ignited or
compression-ignited internal combustion engine comprising
lubricating the engine with a lubricating oil composition as
defined in accordance with the first aspect of the present
invention.
[0023] In accordance with a third aspect, the present invention
provides the use, in the lubrication of a spark-ignited or
compression-ignited internal combustion engine, of an oil-soluble
or oil-dispersible polymeric friction modifier (B) as defined in
the first aspect of the invention, as an additive in an effective
minor amount, in a lubricating oil composition comprising an oil of
lubricating viscosity in a major amount to reduce and/or inhibit
corrosion (i.e. suppress the corrosion) of the non-ferrous metal
containing engine components during operation of the engine.
Suitably, the non-ferrous metal containing engine components
include copper, lead, or an alloy of such metals.
[0024] Suitably, the lubricating oil composition as defined in the
third aspect of the invention further includes a dihydrocarbyl
dithiophosphate metal salt as defined in the first aspect of the
present invention, as an additive in an effective minor amount.
[0025] In accordance with a fourth aspect, the present invention
provides the use, in the lubrication of a spark-ignited or
compression-ignited internal combustion engine, of an oil-soluble
or oil-dispersible polymeric friction modifier (B) as defined in
the first aspect of the invention, as an additive in an effective
minor amount, in combination with an oil-soluble or oil-dispersible
dihydrocarbyl dithiophosphate metal salt (C) as defined in the
first aspect of the present invention, as an additive in an
effective minor amount, in a lubricating oil composition comprising
an oil of lubricating viscosity in a major amount, to reduce and/or
inhibit corrosion (i.e. suppress the corrosion) of the non-ferrous
metal containing engine components during operation of the engine.
Suitably, the non-ferrous metal containing engine components
include copper, lead or an alloy of such metals, especially copper
or an alloy thereof.
[0026] In accordance with a fifth aspect, the present invention
provides the use, in the lubrication of a spark-ignited or
compression-ignited internal combustion engine, of a lubricating
oil composition in accordance with the first aspect of the present
invention to reduce and/or inhibit corrosion (i.e. suppress the
corrosion) of the non-ferrous containing metallic engine components
during operation of the engine. Suitably, the non-ferrous metal
containing engine components include copper, lead or an alloy of
such metals, especially copper or an alloy thereof.
[0027] In accordance with a sixth aspect, the present invention
provides a method of inhibiting and/or reducing the corrosion (i.e.
suppressing the corrosion) of the non-ferrous metal containing
engine components of an engine, which method comprises lubricating
the engine with a lubricating oil composition which comprises an
oil of lubricating viscosity in a major amount and an oil-soluble
or oil-dispersible polymeric friction modifier (B) as defined in
the first aspect of the invention, as an additive in an effective
minor amount, and operating the engine. Suitably, the non-ferrous
metal containing engine components include copper, lead or an alloy
of such metals. Suitably, the engine as defined in the sixth aspect
of the present invention is a spark-ignited or compression-ignited
internal combustion engine.
[0028] In accordance with a seventh aspect, the present invention
provides a method of inhibiting and/or reducing the corrosion (i.e.
suppressing the corrosion) of the non-ferrous metal containing
engine components of an engine, which method comprises lubricating
the engine with a lubricating oil composition of the first aspect
of the present invention and operating the engine. Suitably, the
non-ferrous metal containing engine components include copper, lead
or an alloy of such metals, especially copper or an alloy thereof.
Suitably, the engine as defined in the seventh aspect of the
present invention is a spark-ignited or compression-ignited
internal combustion engine.
[0029] Preferably, the oil-soluble or oil-dispersible dihydrocarbyl
dithiophosphate metal salt (C) is an oil-soluble or oil-dispersible
dihydrocarbyl dithiophosphate zinc salt (i.e. a zinc dihydrocarbyl
dithiophosphate (ZDDP)), more preferably an oil-soluble or
oil-dispersible zinc dialkyl dithiophosphate.
[0030] Preferably, the lubricating oil composition of the first
aspect of the present invention and as defined in the second,
third, fourth, fifth, sixth and seventh aspects of the present
invention further includes one or more co-additives in an effective
minor amount, other than additive components (B) and (C), selected
from ashless dispersants, metal detergents, corrosion inhibitors,
antioxidants, pour point depressants, antiwear agents, friction
modifiers, demulsifiers, antifoam agents and viscosity
modifiers.
[0031] The lubricating oil composition of the present invention has
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.
[0032] Preferably, the lubricating oil composition of the present
invention contains low levels of phosphorus. The lubricating oil
composition contains phosphorus in an amount of less than or equal
to 0.12 mass %, preferably up to 0.11 mass %, more preferably less
than or equal to 0.10 mass %, even more preferably less than or
equal to 0.09 mass %, even more preferably less than or equal to
0.08 mass %, most preferably less than or equal to 0.06, mass % of
phosphorus (ASTM D5185) based on the total mass of the composition.
Suitably, the lubricating oil composition contains phosphorus in an
amount of greater than or equal to 0.01, preferably greater than or
equal to 0.02, more preferably greater than or equal to 0.03, even
more preferably greater than or equal to 0.05, mass % of phosphorus
(ASTM D5185) based on the total mass of the composition.
[0033] Typically, the lubricating oil composition of the present
invention may contain low levels of sulfur. Preferably, the
lubricating oil composition contains sulphur in an amount of up to
0.4, more preferably up to 0.3, even more preferably up to 0.2,
mass % sulphur (ASTM D2622) based on the total mass of the
composition.
[0034] Typically, a lubricating oil composition according to the
present invention contains up to 0.30, more preferably up to 0.20,
most preferably up to 0.15, mass % nitrogen, based on the total
mass of the composition and as measured according to ASTM method
D5291.
[0035] Suitably, the lubricating oil composition may have a total
base number (TBN), as measured in accordance with ASTM D2896, of 4
to 15, preferably 5 to 12, mg KOH/g.
[0036] In this specification, the following words and expressions,
if and when used, have the meanings given below: [0037] "active
ingredients" or "(a.i.)" refers to additive material that is not
diluent or solvent; [0038] "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; [0039] "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; [0040] "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; [0041] "alkynyl" 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 triple bond and is
bonded to the remainder of the compound directly via a single
carbon atom, and is otherwise defined as "alkyl"; [0042] "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; [0043] "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"; [0044] "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; [0045] "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; [0046] "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; [0047] "halo" or "halogen"
includes fluoro, chloro, bromo and iodo; [0048] "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; [0049] "ashless" in relation to an additive
means the additive does not include a metal; [0050]
"ash-containing" in relation to an additive means the additive
includes a metal; [0051] "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; [0052] "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; [0053] "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; [0054] "non-ferrous metal"
includes a metal or an alloy thereof comprising lead, copper, tin,
or an alloy thereof of such metals, preferably a metal of copper or
lead, or an alloy thereof of such metals, especially copper or an
alloy thereof; [0055] non-ferrous metal corrosion (e.g. corrosion
of copper and lead) is measured by the High Temperature Corrosion
Bench Test in accordance with ASTM D6594; [0056] "ppm" means parts
per million by mass, based on the total mass of the lubricating oil
composition; [0057] "metal content" of the lubricating oil
composition or of an additive component, for example molybdenum
content or total metal content of the lubricating oil composition
(i.e. the sum of all individual metal contents), is measured by
ASTM D5185; [0058] "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; [0059]
"KV.sub.100" means kinematic viscosity at 100.degree. C. as
measured by ASTM D445; [0060] "phosphorus content" is measured by
ASTM D5185; [0061] "sulfur content" is measured by ASTM D2622; and,
[0062] "sulfated ash content" is measured by ASTM D874.
[0063] All percentages reported are mass % on an active ingredient
basis, i.e. without regard to carrier or diluent oil, unless
otherwise stated.
[0064] 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.
[0065] Further, it is understood that any upper and lower quantity,
range and ratio limits set forth herein may be independently
combined.
[0066] 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.
DETAILED DESCRIPTION OF THE INVENTION
[0067] The features of the invention relating, where appropriate,
to each and all aspects of the invention, will now be described in
more detail as follows:
Oil of Lubricating Viscosity (A)
[0068] 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.
[0069] 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.
[0070] 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: [0071] 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. [0072] 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. [0073] 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. [0074] d) Group IV base stocks are polyalphaolefins
(PAO). [0075] e) Group V base stocks include all other base stocks
not included in Group I, II, III, or IV.
TABLE-US-00001 [0075] 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
[0076] Other oils of lubricating viscosity which may be included in
the lubricating oil composition are detailed as follows:
[0077] 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.
[0078] 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(l-octenes), poly(l-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.
[0079] 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.
[0080] 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.
[0081] 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.
[0082] 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.
[0083] 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 base oil of a
lubricating oil composition according to the present invention
typically comprises no more than 85 mass % Group IV base oil, the
base oil may comprise no more than 70 mass % Group IV base oil, or
even no more than 50 mass % Group IV base oil. The base oil of a
lubricating oil composition according to the present invention may
comprise 0 mass % Group IV base oil. Alternatively, the base oil of
a lubricating oil composition according to the present invention
may comprise at least 5 mass %, at least 10 mass % or at least 20
mass % Group IV base oil. The base oil of a lubricating oil
composition according to the present invention may comprise from 0
to 85 mass %, or from 5-85 mass %, alternatively from 10-85 mass %
Group IV base oil.
[0084] 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.
[0085] The oil of lubricating viscosity is provided in a major
amount, in combination with a minor amount of additive components
(B) and (C), as defined herein and, if necessary, one or more
co-additives, such as described hereinafter, constituting a
lubricating oil composition. This preparation may be accomplished
by adding the additives directly to the oil or by adding them in
the form of a concentrate thereof to disperse or dissolve the
additive. Additives may be added to the oil by any method known to
those skilled in the art, either before, at the same time as, or
after addition of other additives.
[0086] 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 65 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.
[0087] When concentrates are used to make the lubricating oil
compositions, they may for example be diluted with 3 to 100, e.g. 5
to 40, parts by mass of oil of lubricating viscosity per part by
mass of the concentrate.
[0088] Preferably, the lubricating oil composition is a multigrade
oil identified by the viscometric descriptor SAE 20WX, SAE 15WX,
SAE 10WX, SAE 5WX or SAE 0WX, 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 0WX, preferably in the form of a SAE 5WX
or SAE 0WX, wherein X represents any one of 20, 30, 40 and 50.
Preferably X is 20 or 30.
Polymeric Friction Modifier (B)
[0089] The oil-soluble or oil-dispersible polymeric friction
modifier (B) is the reaction product of solely: [0090] (i) a
functionalised polyolefin; [0091] (ii) a polyalkylene glycol;
[0092] (iii) a polyol; and, [0093] (iv) a polycarboxylic acid.
[0094] By the word "solely", we mean the oil-soluble or
oil-dispersible polymeric friction modifier (B), as defined in each
aspect of the present invention, is a copolymer derived from the
reaction of only a functionalised polyolefin, a polyalkylene
glycol, a polyol and a polycarboxylic acid.
The Functionalised Polyolefin (B(i))
[0095] The functionalised polyolefin is preferably derived from
polymerisation of an olefin, especially a mono-olefin, having from
2 to 6 carbon atoms, such as ethylene, propylene, but-1-ene and
isobutylene (i.e. 2-methyl propene) and the resulting polyolefin
functionalised with an appropriate functional group. Accordingly,
the functionalised polyolefin may be regarded as a functionalised
poly(C.sub.2 to C.sub.6 alkylene). Even more preferably, the
functionalised polyolefin is derived from polymerisation of
isobutylene and the resulting polyisobutylene functionalised with
an appropriate functional group (i.e. the functionalised polyolefin
is functionalised polyisobutylene).
[0096] The polyolefin of the functionalised polyolefin suitably
includes a chain of 15 to 500, preferably 50 to 200, carbon atoms.
Suitably, the polyolefin of the functionalised polyolefin has a
number average molecular weight (Mn) of from 300 to 5000,
preferably 500 to 1500, especially 800 to 1200 daltons.
[0097] The functionalised polyolefin includes at least one
functional group which is capable of reacting with a hydroxyl
functional group of the polyalkylene glycol (B(ii)) or a hydroxyl
group of the polyol (B(iii)). Accordingly, the functionalised
polyolefin may comprise a diacid or anhydride functional group from
reaction of the polyolefin with an unsaturated diacid or anhydride;
alternatively, the functionalised polyolefin may comprise an
epoxide functional group from reaction with a peracid, for example
perbenzoic acid or peracetic acid. Preferably, the functionalised
polyolefin includes an anhydride functional group. Suitably the
anhydride functionalised polyolefin is derived from the reaction of
the polyolefin with an anhydride, especially maleic anhydride which
forms a succinic anhydride functional group. Accordingly, the
functionalised polyolefin includes an anhydride functional group,
especially a succinic anhydride functional group.
[0098] Accordingly, a preferred functionalised polyolefin is a
polyolefin which includes an anhydride functional group, more
preferably a functionalised poly(C.sub.2 to C.sub.6 alkylene) which
includes an anhydride functional group, even more preferably a
functionalised poly(C.sub.2 to C.sub.6 alkylene) which includes a
succinic anhydride functional group, especially a polyisobutylene
(PIB) which includes a succinic anhydride functional group--namely
polyisobutylene succinic anhydride (PIBSA). Suitably, the
polyisobutylene of the PIBSA has a number average molecular weight
(Mn) of from 300 to 5000, preferably 500 to 1500, especially 800 to
1200 daltons. PIB is a commercially available compound and sold
under the trade name of Glissopal by BASF and this product can be
reacted to give a functionalised polyolefin (B(i)).
The Polyalkylene Glycol (B(ii))
[0099] Suitably, the polyalkylene glycol comprises a poly(C.sub.2
to C.sub.20 alkylene) glycol, preferably a poly(C.sub.2 to C.sub.10
alkylene) glycol, more preferably a poly(C.sub.2 to C.sub.6
alkylene) glycol. A preferred polyalkylene glycol is polyethylene
glycol or polypropylene glycol or a mixed poly(ethylene-propylene)
glycol. The most preferred polyalkylene glycol is polyethylene
glycol (PEG), especially a water soluble PEG.
[0100] The polyalkylene glycol includes two hydroxyl groups which
are capable of reacting with the functional group of the
functionalised polyolefin (B(i)), thereby forming an essentially
polyolefin-polyalkylene glycol copolymer, and/or reacting with the
polycarboxylic acid (B(iv)), thereby forming an essentially
polyolefin-polyalkylene glycol-carboxylic acid compound or a
polyalkylene glycol-carboxylic acid compound. It will be
appreciated that such compounds may react further with the
functionalised polyolefin (B(i)), the polyalkylene glycol (B(ii)),
the polyol (B(iii)) and/or the polycarboxylic acid (B(iv)).
[0101] Suitably, the polyalkylene glycol (e.g. PEG) has a number
average molecular weight (Mn) of from 300 to 5000, preferably 400
to 1000, especially 400 to 800, daltons. Accordingly, in a
preferred embodiment the polyalkylene glycol (B(ii)) is
PEG.sub.400, PEG.sub.600 or PEG.sub.1000. Suitably, PEG.sub.400,
PEG.sub.600 and PEG.sub.1000 are commercially available from Croda
International.
The Polyol (B(iii))
[0102] The polyol reactant is capable of reacting with the
functionalised polyolefin thereby providing a backbone moiety which
links together separate blocks of functionalised polyolefin.
Suitably, when the functionalised polyolefin is functionalised with
an anhydride or diacid functional group, the polyol provides a
backbone moiety which links together, via ester bonds, separate
blocks of the polyolefin.
[0103] Suitably, the polyol reactant is also capable of reacting
with the polycarboxylic acid thereby providing a polyol-carboxylic
acid compound, wherein such compound may react further with the
functionalised polyolefin (B(i)) and/or the polyalkylene glycol
(B(ii)).
[0104] The polyol is 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.
Accordingly, the polyol may be a diol, trial, tetrol, and/or
related dimers or chain extended polymers of such compounds.
Suitably, the polyol comprises a C.sub.2 to C.sub.20 hydrocarbyl
polyol, more preferably a C.sub.2 to C.sub.20 aliphatic hydrocarbyl
polyol. Examples of suitable polyols include glycerol, neopentyl
glycol, trimethylolethane, trimethylolpropane, trimethylolbutane,
pentaerythritol, dipentaerythritol, tripentaerythritol and
sorbitol. A highly preferred polyol is glycerol.
The Polycarboxylic Acid (B(iv))
[0105] The polycarboxylic acid reactant is capable of reacting with
the hydroxyl group of the polyalkylene glycol (B(ii)) thereby
providing a back bone moiety which links together, via ester bonds,
separate blocks of polyalkylene glycol.
[0106] Suitably, the polycarboxylic acid is also capable of
reacting with the polyol (B(iii)), thereby providing a
polyol-carboxylic acid compound, wherein such compound may react
further with the functionalised polyolefin (B(i)) and/or the
polyalkylene glycol (B(ii)).
[0107] The polycarboxylic acid is an organic acid which has two or
more carboxylic acid groups. The polycarboxylic acid may be a di-,
tri- and tetra-carboxylic acid; dicarboxylic acids are preferred.
Suitably, the polycarboxylic acid comprises a C.sub.2 to C.sub.30
hydrocarbyl polycarboxylic acid, preferably a C.sub.2 to C.sub.20
hydrocarbyl polycarboxylic acid, even more preferably a C.sub.2 to
C.sub.30 hydrocarbyl dicarboxylic acid, still more preferably a
C.sub.2 to C.sub.20 hydrocarbyl dicarboxylic acid. Still even more
preferably, the polycarboxylic acid comprises an acyclic C.sub.2 to
C.sub.30 aliphatic hydrocarbyl dicarboxylic acid, even more
preferably an acylic C.sub.2 to C.sub.20 aliphatic hydrocarbyl
dicarboxylic acid. Linear polycarboxylic acids are preferred to
branched chain polycarboxylic acids. Saturated polycarboxylic acids
are preferred to unsaturated polycarboxylic acids, such as maleic
acid.
[0108] Highly preferred polycarboxylic acids include oxalic acid,
malonic acid, succinic acid, glutaric acid, adipic acid, pimelic
acid, suberic acid, azelaic acid and sebacic acid. The most
preferred polycarboxylic acid is sebacic acid.
[0109] Thus according to a highly preferred embodiment the
oil-soluble or oil-dispersible polymeric friction modifier (B) is
the reaction product of solely: [0110] (i) PIBSA, as defined
herein; [0111] (ii) polyethylene glycol, as defined herein; [0112]
(iii) a polyol, preferably glycerol; and [0113] (iv) a
polycarboxylic acid, preferably sebacic acid.
[0114] Suitably, during formation of the polymeric friction
modifier multiple reactions between the functionalised polyolefin
(B(i)), polyalkylene glycol (B(ii)), polyol (B(iii)) and
polycarboxylic acid (B(iv)) may occur. For example, the
functionalised polyolefin and the polyalkylene glycol may react so
that the polyolefin is linked directly to the polyalkylene glycol
(e.g. via an ester bond) and subsequent reactions may occur between
the resulting polymer with either the functionalised polyolefin,
polyalkylene glycol, polyol and/or polycarboxylic acid.
Alternatively, or additionally, the polyalkylene glycol may react
with the polycarboxylic acid to form blocks of polyalkylene glycol
linked together by the esterified polycarboxylic acid and
subsequent reactions may occur between the resulting blocks of
polyalkylene glycol with the functionalised polyolefin and/or
blocks of the functionalised polyolefin. Still further, the
functionalised polyolefin may react with the polyol to form blocks
of the functionalised polyolefin linked together (typically via an
ester linkage) by the polyol and subsequent reactions may occur
between the resulting blocks of functionalised polyolefin with the
polyalkylene glycol and/or blocks of the polyalkylene glycol.
[0115] Accordingly, the functionalised polyolefin, polyalkylene
glycol, polyol and polycarboxylic acid may react to form a block
copolymer. When present the number of block copolymer units in the
organic friction modifier additive typically ranges from 2 to 20,
preferably 2 to 15, more preferably 2 to 10, units.
[0116] As with all polymers, the polymeric friction modifier will
typically comprise a mixture of molecules of various sizes. The
polymeric friction modifier (B) suitably has a number average
molecular weight of from 1,000 to 30,000, preferably from 1,500 to
25,000, more preferably from 2,000 to 20,000, daltons.
[0117] The polymeric friction modifier (B) suitably has an acid
value of less than 20, preferably less than 15 and more preferably
less than 10 mg KOH/g (ASTM D974). The polymeric friction modifier
(B) suitably has an acid value of greater than 1, preferably
greater than 1.5 mg KOH/g. In a preferred embodiment, the polymeric
friction modifier (B) has an acid value in the range of 1.5 to
9.
[0118] In a preferred embodiment the polymeric friction modifier
(B) is a reaction product of maleinised polyisobutylene (PIBSA),
PEG, glycerol and sebacic acid, wherein the polyisobutylene of the
maleinised polyisobutylene (PIBSA) has a number average molecular
weight of around 950 daltons, the PIBSA has an approximate
saponification value of 98 mg KOH/g and the PEG has a number
average molecular weight of around 600 daltons and a hydroxyl value
of 190 mg KOH/g. A suitable additive may be made by charging 158.4
g (0.128 mol) of PIBSA, 101 g (0.168 mol) of PEG.sub.600, 10.4 g
(0.0514 mol) of sebacic acid and 7.7 g (0.0835 mol) of glycerol
into a glass round bottomed flask equipped with a nitrogen purge,
mechanical stirrer, isomantle heater and distillation arm. The
reaction takes place in the presence of 0.5 ml of esterification
catalyst tetrabutyl titanate at 180-230.degree. C., with removal of
water to a final acid value of 1.7 mg/KOH/g. Accordingly,
alternative polymeric friction modifiers (B) may be prepared by
analogous synthetic methods.
[0119] The polymeric friction modifier (B) is suitably present in
the lubricating oil composition of the present invention, on an
active matter basis, in an amount of at least 0.1, preferably at
least 0.2, mass % based on the total mass of the lubricating oil
composition. The polymeric friction modifier of the present
invention is suitably present in the lubricating oil composition,
on an active matter basis, in an amount of less than or equal to 5,
preferably less than or equal to 3, more preferably less than or
equal to 1.5, mass %, based on the total mass of the lubricating
oil composition.
Dihydrocarbyl Dithiophosphate Metal Salt (C)
[0120] For the lubricating oil compositions of the present
invention, any suitable oil-soluble or oil-dispersible
dihydrocarbyl dithiophosphate metal salt having anti-wear
properties in lubricating oil compositions may be employed.
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. Accordingly, a preferred dihydrocarbyl dithiophosphate metal
salt is zinc dihydrocarbyl dithiophosphate (ZDDP), more preferably
zinc dialkyl dithiophosphate, especially zinc di(C.sub.2 to C.sub.8
alkyl) dithiophosphate wherein the C.sub.2 to C.sub.8 alkyl groups
of the zinc di(C.sub.2 to C.sub.8 alkyl) dithiophosphate may be the
same or different.
[0121] 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.
[0122] The preferred zinc dihydrocarbyl dithiophosphates (ZDDP) are
oil-soluble salts of dihydrocarbyl dithiophosphoric acids and may
be represented by the following formula:
##STR00001##
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.
[0123] The ZDDP is added to the lubricating oil compositions in
amounts sufficient to provide no greater than 1200 ppm, preferably
no greater than 1000 ppm, more preferably no greater than 900 ppm,
most preferably no greater than 850 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. The
ZDDP is suitably added to the lubricating oil compositions in
amounts sufficient to provide at least 100 ppm, preferably at least
350 ppm, more preferably at least 500 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.
Engines
[0124] The lubricating oil compositions of the invention may be
used to lubricate mechanical engine components, particularly in
internal combustion engines, e.g. spark-ignited or
compression-ignited internal combustion engines, particularly
spark-ignited or compression-ignited two- or four-stroke
reciprocating engines, by adding the composition thereto. The
engines may be conventional gasoline or diesel engines designed to
be powered by gasoline or petroleum diesel, respectively;
alternatively, the engines may be specifically modified to be
powered by an alcohol based fuel or biodiesel fuel.
Co-Additives
[0125] Co-additives, with representative effective amounts, that
may also be present, different from additive components (B) and
(C), are listed 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) Ashless
Dispersant 0.1-20 1-8 Metal Detergents 0.1-15 0.2-9 Friction
modifier 0-5 0-1.5 Corrosion Inhibitor 0-5 0-1.5 Metal
Dihydrocarbyl Dithiophosphate 0-10 0-4 Anti-Oxidants 0-5 0.01-3
Pour Point Depressant 0.01-5 0.01-1.5 Anti-Foaming Agent 0-5
0.001-0.15 Supplement Anti-Wear Agents 0-5 0-2 Viscosity Modifier
(1) 0-10 0.01-4 Mineral or Synthetic Base Oil Balance Balance (1)
Viscosity modifiers are used only in multi-graded oils.
[0126] 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
co-additives, the remainder being oil of lubricating viscosity.
[0127] Suitably, the lubricating oil composition includes one or
more co-additives in a minor amount, other than additive components
(B) and (C), selected from ashless dispersants, metal detergents,
corrosion inhibitors, antioxidants, pour point depressants,
antiwear agents, friction modifiers, demulsifiers, antifoam agents
and viscosity modifiers.
[0128] 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.
[0129] Metal 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.
[0130] 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
lubricant, and mixtures of calcium and/or magnesium with sodium.
Combinations of detergents, whether overbased or neutral or both,
may be used.
[0131] In one embodiment of the present invention, the lubricating
oil composition includes metal detergents that are chosen from
neutral or overbased calcium sulfonates having TBN of from 20 to
450 mg KOH/g, and neutral and overbased calcium phenates and
sulfurized phenates having TBN of from 50 to 450 mg KOH/g, and
mixtures thereof.
[0132] 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.
[0133] 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.
[0134] In another embodiment of the present invention, the
lubricating oil composition comprises metal detergents that are
neutral or overbased alkali or alkaline earth metal salicylates
having a TBN of from 50 to 450 mg KOH/g, preferably a TBN of 50 to
250 mg KOH/g, or mixtures thereof. Highly preferred salicylate
detergents include alkaline earth metal salicylates, particularly
magnesium and calcium, especially, calcium salicylates. In one
embodiment of the present invention, alkali or alkaline earth metal
salicylate detergents are the sole metal-containing detergent in
the lubricating oil composition.
[0135] Supplemental anti-wear agents, other than dihydrocarbyl
dithiophosphate metal salts (additive component (C)), which may be
included in the lubricating oil composition comprise
1,2,3-triazoles, benzotriazoles, sulfurised fatty acid esters, and
dithiocarbamate derivatives.
[0136] Ashless dispersants comprise an oil-soluble polymeric
hydrocarbon backbone having functional groups that are capable of
associating with particles to be dispersed. Typically, the
dispersants comprise amine, alcohol, amide, or ester polar moieties
attached to the polymer backbone often via a bridging group. The
ashless dispersants may be, for example, selected from oil-soluble
salts, esters, amino-esters, amides, imides, and oxazolines of long
chain hydrocarbon substituted mono and dicarboxylic acids or their
anhydrides; thiocarboxylate derivatives of long chain hydrocarbons;
long chain aliphatic hydrocarbons having a polyamine attached
directly thereto; and Mannich condensation products formed by
condensing a long chain substituted phenol with formaldehyde and a
polyalkylene polyamine.
[0137] Friction modifiers include glycerol monoesters of higher
fatty acids, for example, glycerol mono-oleate (GMO); esters of
long chain polycarboxylic acids with diols, for example, the butane
diol ester of a dimerized unsaturated fatty acid; oxazoline
compounds; and alkoxylated alkyl-substituted mono-amines, diamines
and alkyl ether amines, for example, ethoxylated tallow amine and
ethoxylated tallow ether amine.
[0138] Typically, the total amount of additional organic ashless
friction modifier in a lubricant according to 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 %. In an embodiment of
the present invention, the lubricating oil composition contains no
additional organic ashless friction modifier.
[0139] Other known friction modifiers comprise oil-soluble
organo-molybdenum compounds. Such organo-molybdenum friction
modifiers also provide antioxidant and antiwear credits to a
lubricating oil composition. Suitable oil-soluble organo-molybdenum
compounds have a molybdenum-sulfur core. As examples there may be
mentioned dithiocarbamates, dithiophosphates, dithiophosphinates,
xanthates, thioxanthates, sulfides, and mixtures thereof.
Particularly preferred are molybdenum dithiocarbamates,
dialkyldithiophosphates, alkyl xanthates and alkylthioxanthates.
The molybdenum compound is dinuclear or trinuclear.
[0140] One class of preferred organo-molybdenum compounds useful in
all aspects of the present invention is tri-nuclear molybdenum
compounds 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
compounds soluble or dispersible in the oil, n is from 1 to 4, k
varies from 4 through to 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.
[0141] The molybdenum compounds may be present in a lubricating oil
composition at a concentration in the range 0.1 to 2 mass %, or
providing at least 10 such as 50 to 2,000 ppm by mass of molybdenum
atoms.
[0142] Preferably, the molybdenum from the molybdenum compound is
present in an amount of from 10 to 1500, such as 20 to 1000, more
preferably 30 to 750, ppm based on the total weight of the
lubricating oil composition. For some applications, the molybdenum
is present in an amount of greater than 500 ppm.
[0143] 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,
styrenelbutadiene, and isoprene/butadiene, as well as the partially
hydrogenated homopolymers of butadiene and isoprene and
isoprene/divinylbenzene.
[0144] 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.
[0145] Examples of suitable antioxidants are selected from
copper-containing antioxidants, sulfur-containing antioxidants,
aromatic amine-containing antioxidants, hindered phenolic
antioxidants, dithiophosphates derivatives, and metal
thiocarbamates. Preferred anti-oxidants are aromatic
amine-containing antioxidants, hindered phenolic antioxidants and
mixtures thereof. In a preferred embodiment, an antioxidant is
present in a lubricating oil composition of the present
invention.
[0146] Rust inhibitors selected from the group consisting of
nonionic polyoxyalkylene polyols and esters thereof,
polyoxyalkylene phenols, and anionic alkyl sulfonic acids may be
used.
[0147] Copper and lead bearing corrosion inhibitors may be used,
but are typically not required with the formulation of the present
invention. Typically 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. When these
compounds are included in the lubricating composition, they are
preferably present in an amount not exceeding 0.2 wt. % active
ingredient.
[0148] 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.
[0149] 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.
[0150] Foam control can be provided by many compounds including an
antifoamant of the polysiloxane type, for example, silicone oil or
polydimethyl siloxane.
[0151] 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.
[0152] 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.
[0153] 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.
[0154] Typically, the additive package used to formulate the
lubricating oil composition according to the present invention has
a total base number (TBN) as measured by ASTM D2896 of 25 to 100,
preferably 45 to 80, and the lubricating oil composition according
to the present invention has a total base number (TBN) as measured
by ASTM D2896 of 4 to 15, preferably 5 to 12. In an embodiment of
the present invention, the additive package does not have a total
base number (TBN) as measured by ASTM D2896 of between 62 and 63.5
and the lubricating oil composition does not have a total base
number (TBN) as measured by ASTM D2896 of between 9.05 and
9.27.
[0155] 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.
[0156] In an embodiment of the present invention, a lubricating oil
composition according to the first aspect of the invention does not
comprise 0.2-0.25 mass % of sulphur as measured according to ASTM
method D4927.
[0157] In an embodiment of the present invention, a lubricating oil
composition according to the first aspect of the invention does not
comprise 0.08-0.11 mass % of nitrogen as measured according to ASTM
method D5291.
EXAMPLES
[0158] The invention will now be described in the following
examples which are not intended to limit the scope of the claims
hereof.
[0159] Unless otherwise specified, all of the additives described
in the Examples are available as standard additives from lubricant
additive companies such as Infineum UK Ltd, Lubrizol Corporation
and Afton Chemical Corporation.
Example 1
Preparation of Polymeric Friction Modifier (B)
[0160] A 500 cm.sup.3 5-necked round-bottomed flask equipped with a
nitrogen purge, stirrer with a gas-tight stirrer bearing,
temperature probe and distillation arm attached to an exit bubbler
was charged with PIBSA (158.4 g, 0.128 mol), PEG.sub.600 (101.0 g,
0.168 mol), sebacic acid (10.4 g, 0.0514 mol) and glycerol (7.7 g,
0.0835 mol) and the mixture heated at 180.degree. C. with stirring
for 1 hour. The reaction mixture was then heated to a temperature
of 230.degree. C. for 1 hour and then tetrabutyl titanate (0.5 ml)
added thereto and heating and stirring continued for 2 hours at a
temperature of 230.degree. C. and a reduced pressure of between 50
to 150 mbar. The reaction mixture was cooled to below 100.degree.
C. and the polymeric friction modifier (B) poured from the round
bottom flask. The polymeric friction modifier (B) had an acid value
of 1.7 mg KOH/g.
Example 2
Anti-Corrosion Performance
[0161] Six lubricating oil compositions (referred to as the base
lubricant and Oils 1 to 5) were prepared. Each of the base
lubricant and Oils 1 to 5 contained an identical Group II base
stock and equal amounts of the following identical additives: an
overbased calcium sulphonate detergent (TBN 300 mg KOH/g); a
dispersant; anti-oxidants; a molybdenum friction modifier; and a
viscosity modifier. Oils 1 to 5 also included the additional
additive(s), on an active ingredient basis, as detailed in Table 1.
Those oils which included ZDDP (i.e. Oils 3 to 5) had a phosphorus
content of 880 ppm as measured by ASTM D5185. Oil 5 represents a
lubricating oil composition of the present invention.
TABLE-US-00003 TABLE 1 Base Oil 1 Oil 2 Oil 3 Oil 4 Oil 5 Component
lubricant Mass % Mass % Mass % Mass % Mass % ZDDP -- -- -- 1.10
1.10 1.10 Polymeric -- 0.50 -- -- -- 0.50 friction modifier
(B).sup.1 Glycerol -- -- 0.50 -- 0.50 -- monooleate .sup.1The
polymeric friction modifier was the compound of Example 1.
Testing and Results
[0162] Corrosion control is measured using the High Temperature
Corrosion Bench Test (HTCBT) in accordance with ASTM D6594-06. This
test method simulates the corrosion of non-ferrous metals, such as
copper and lead found in cam followers and bearings, in lubricants;
the corrosion process under investigation being induced by
lubricant chemistry rather than lubricant degradation or
contamination.
[0163] Four metal specimens of copper, lead, tin and phosphor
bronze are immersed in a measured amount of a test lubricating oil
(100 ml) within a sample tube. The sample tube is immersed in a
heated oil bath so that the temperature of the test lubricating oil
is heated to 135.degree. C. The test lubricating oil is heated at
135.degree. C. for 168 hours and during this time dry air is blown
through the heated oil at a rate of 5 litres per hour. After which,
the test lubricating oil is cooled and the metal specimens removed
and examined for corrosion. The concentration of copper, tin and
lead in the test lubricating oil composition and a reference sample
of the lubricating oil composition (i.e. a new sample of the test
lubricating oil) is then determined in accordance with ASTM D5185.
The difference between the concentration of each of the metal
contaminants in the test lubricating oil composition and those of
the reference sample lubricating oil composition provides a value
for the change in the various metal concentrations before and after
the test. The industry standard limits to meet the requirements of
API CJ-4 are 20 ppm maximum for copper and 120 ppm maximum for
lead. The results for the base lubricant and Oils 1 to 5 are set
out in Table 2.
TABLE-US-00004 TABLE 2 Base Corrosion lubricant Oil 1 Oil 2 Oil 3
Oil 4 Oil 5 Lead (ppm) 23 13 403 63 420 108 Copper (ppm) 33 29 49
27 22 9
[0164] It can be seen from the results in Table 2 that the base
lubricant which does not include ZDDP, an ashless organic friction
modifier or the polymeric friction modifier (B) produces 23 ppm of
lead corrosion and 33 ppm of copper corrosion. A comparison of the
results of Oil 1, which is equivalent to the base lubricant that
includes the polymeric friction modifier (B), with those of the
base lubricant demonstrate that the inclusion of the polymeric
friction modifier (B) in Oil 1 inhibits corrosion of both copper
(29 ppm versus 33 ppm) and lead (13 ppm versus 23 ppm). In
contrast, the inclusion of an ashless organic friction modifier
(GMO) in the base lubricant (Oil 2) significantly enhances both
lead (403 ppm versus 23 ppm) and copper (49 ppm versus 33 ppm)
corrosion.
[0165] As can be seen by a comparison of the results of Oil 3 with
those of the base lubricant, the inclusion of ZDDP in the base
lubricant increases lead corrosion (63 ppm versus 23 ppm) but shows
a marginal improvement in copper corrosion (27 ppm versus 33 ppm).
As can be seen from a comparison of the results of Oil 4 with those
of the base lubricant, the inclusion of both ZDDP and an ashless
organic friction modifier (GMO) in the base lubricant (Oil 4)
significantly increases lead corrosion (420 ppm versus 23 ppm) but
provides an improvement in copper corrosion (22 ppm versus 33 ppm).
It is noticeable from a comparison of the results of Oil 5 (a
lubricant of the invention which includes ZDDP and the polymeric
friction modifier (B)) with those of Oil 4, that the polymeric
friction modifier (B) provides significantly less lead corrosion
than the ashless organic friction modifier present in Oil 4 (108
ppm versus 420 ppm) and the polymeric friction modifier is far
superior than the ashless organic friction modifier at inhibiting
copper corrosion (9 ppm versus 22 ppm). Moreover, a comparison of
the results of Oil 5 with those of the base lubricant clearly
demonstrate that the presence of both ZDDP and the polymeric
friction modifier provides a significant decrease in copper
corrosion (9 ppm versus 33 ppm).
* * * * *