Note: Descriptions are shown in the official language in which they were submitted.
LUBRICATING OIL COMPOSITION CONTAINING POLYMERIC FRICTION
MODIFIERS HAVING, FUNCTIONALIZED POLYOLEFIN, POLYALKYLENE
GLYCOL, POLYOL, AND POLYCARBOXYLIC ACID THEREIN
FIELD OF THE INVENTION
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
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.
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.
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
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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.
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.
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.
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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
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:
(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) polyethylene glycol or polypropylene glycol or a mixed
poly(ethylene-propylene) glycol; and,
(iii) a monocarboxylic acid;
and,
(C) at
least one oil-soluble or oil-dispersible dihydrocarbyl dithiophosphate
metal salt as an additive in an effective minor amount.
Preferably, the lubricating oil composition of the present invention is a
crankcase
lubricant.
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
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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.
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.
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
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salt but not the polymeric friction modifier (B); and, (ii) a comparable
lubricant which
does not include both the dihydrocarbyl dithiophosphate metal salt and the
polymeric
friction modifier (B).
.. 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.
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.
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.
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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.
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.
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.
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
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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.
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.
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.
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 (e.g. 0.1
to 30 mass %), 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.
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.
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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.
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.
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.
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.
In this specification, the following words and expressions, if and when used,
have the
meanings given below:
"active ingredients" or "(a.i.)" refers to additive material that is not
diluent or
solvent;
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"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;
"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",
"ally1" and "aryl" as defined herein;
"alkylene" is synonymous with "alkanediyl" and means a C2 to C20, preferably a
C2 to C10, more preferably a C2 to C6 bivalent saturated acyclic aliphatic
hydrocarbon radical derived from an alkane by removal of a hydrogen atom from
two different carbon atoms; it may be linear or branched. Representative
examples of alkylene include ethylene (ethanediyl), propylene (propanediyl),
butylene (butanediyl), isobutylene, pentylene, hexylene, heptylene, octylene,
nonylene, decylene, 1-methyl ethylene, 1-ethyl ethylene, 1-ethy1-2-methyl
ethylene, 1,1-dimethyl ethylene and 1-ethyl propylene;
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"poly(alkylene)" means a polymer containing the appropriate alkanediy1
repeating
group. Such polymers may be formed by polymerisation of the appropriate
alkene (e.g. polyisobutylene may be formed by polymerising isobutene);
"alkyl" means a C1 to C30 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;
"alkynyl" means a C2 to C30, preferably a C2 to C12, 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";
"aryl" means a C6 to C18, preferably C6 to C10, 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;
"alkenyl" means a C2 to C30, preferably a C2 to C12, 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";
CA 02893404 2015-06-02
"polyol" means an alcohol which includes two or more hydroxyl functional
groups (i.e. a polyhydric alcohol) but excludes a "polyethylene glycol", a
"polypropylene glycol" and a "mixed poly(ethylene-propylene) 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;
"monocarboxylic acid" means a hydrocarbyl monocarboxylic acid which includes
only one carboxylic acid functional group;
"halo" or "halogen" includes fluor , chloro, bromo and iodo;
"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;
"ashless" in relation to an additive means the additive does not include a
metal;
"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;
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"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;
"effective minor amount" in respect of an additive means a minor amount of
such
an additive in a lubricating oil composition so that the additive provides the
desired technical effect;
"non-ferrous metal" includes a metal which is lead, copper or 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;
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;
"ppm" means parts per million by mass, based on the total mass of the
lubricating
oil composition;
"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;
"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;
"KV100" means kinematic viscosity at 100 C as measured by ASTM D445;
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"phosphorus content" is measured by ASTM D5185;
"sulfur content" is measured by ASTM D2622; and,
"sulfated ash content" is measured by ASTM D874.
All percentages reported are mass % on an active ingredient basis, i.e.
without regard to
carrier or diluent oil, unless otherwise stated.
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.
Further, it is understood that any upper and lower quantity, range and ratio
limits set forth
herein may be independently combined. Accordingly, any upper and lower
quantity,
range and ratio limits set forth herein associated with a particular technical
feature of the
present invention may be independently combined with any upper and lower
quantity,
range and ratio limits set forth herein associated with one or more other
particular
technical feature(s) of the present invention. Furthermore, any particular
technical feature
of the present invention, and all preferred variants thereof, may be
independently
combined with any other particular technical feature(s), and all preferred
variants thereof.
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
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:
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OIL OF LUBRICATING VISCOSITY (A)
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
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, mm2/s (cSt) at 100 C.
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:
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.
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.
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.
d) Group IV base stocks are polyalphaolefins (PAO).
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e) Group V base stocks include all other base stocks not included in Group I,
II,
III, or IV.
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
Other oils of lubricating viscosity which may be included in the lubricating
oil
composition are detailed as follows:
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.
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.
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,
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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.
Esters useful as synthetic oils also include those made from C5 to C12
monocarboxylic
acids and polyols, and polyol ethers such as neopentyl glycol,
trimethylolpropane,
pentaerythritol, dipentaerythritol and tripentaerythritol.
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.
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
16
CA 02893404 2015-06-02
containing H2 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.
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 A 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.
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.
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
17
CA 02893404 2015-06-02
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.
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.
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.
Preferably, the lubricating oil composition is a multigrade oil identified by
the
viscometric descriptor SAE 20WX, SAE 15WX, SAE 1 OWX, 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 1 OWX, SAE 5WX or SAE OWX, preferably in
the
form of a SAE 5WX or SAE OWX, wherein X represents any one of 20, 30, 40 and
50.
Preferably X is 20 or 30.
POLYMERIC FRICTION MODIFIER (B)
The oil-soluble or oil-dispersible polymeric friction modifier (B) is the
reaction product
of solely:
(i) a functionalised polyolefin, as defined herein;
(ii) polyethylene glycol or polypropylene glycol or a mixed
poly(ethylene-propylene) glycol; and,
18
CA 02893404 2015-06-02
(iii) a monocarboxylic acid.
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 the functionalised polyolefin (B(i)) with the
polyethylene glycol
or polypropylene glycol or a mixed poly(ethylene-propylene) glycol (B(ii)) and
which
copolymer is terminated (i.e. chain terminated) by reaction with the
monocarboxylic acid
(i.e. a copolymer which is the reaction product of only: one or more
functionalised
polyolefins, as defined herein; one or more polyalkylene glycols selected from
one or
more polyethylene glycols, one or more polypropylene glycols, one or more
poly(ethylene-propylene) glycols, or combinations thereof; and, one or more
monocarboxylic acids).
The polymeric friction modifier (B), as defined herein and in each aspect of
the present
invention, does not include the reaction product of (i) a functionalised
polyolefin, as
defined herein; (ii) a polyalkylene glycol (e.g. a polyethylene glycol or
polypropylene
glycol or a mixed poly(ethylene-propylene) glycol); (iii) a monocarboxylic
acid; and, (iv)
a polyol. In other words, the polymeric friction modifier (B), as defined in
each aspect of
the present invention, does not include a backbone moiety derived from a
polyol which is
capable of reacting with the functionalised polyolefin, as defined herein, or
the
copolymer reaction product derived from the reaction of (B(i)) with (B(ii)).
Accordingly,
in the polymeric friction modifier (B), as defined in each aspect of the
present invention,
the functionalised polyolefin (B(i)) and the polyethylene glycol or
polypropylene glycol
or a mixed poly(ethylene-propylene) glycol (B(ii)) are bonded directly to one
another, via
an appropriate functional group (e.g. via an ester group where the
functionalised
polyolefin includes a diacid or anhydride functional group), and hence form an
essentially polyolefin-polyethylene glycol copolymer or polyolefin-
polypropylene glycol
copolymer or polyolefin-poly(ethylene-propylene) glycol copolymer which
copolymer
chain is terminated by reaction with the monocarboxylic acid (e.g. a free
hydroxyl group
19
CA 02893404 2015-06-02
of the polyethylene glycol or polypropylene glycol or a mixed poly(ethylene-
propylene)
glycol moiety in the copolymer forms an ester by reaction with the
monocarboxylic acid).
Suitably, the lubricating oil composition of the present invention also does
not include a
polymeric friction modifier which is the reaction product of (i) a
functionalised
polyolefin, as defined herein; (ii) a polyalkylene glycol (e.g. a polyethylene
glycol or
polypropylene glycol or a mixed poly(ethylene-propylene) glycol); (iii) a
monocarboxylic acid; and, (iv) a polyol.
The Functionalised Polyolefin (B(i))
The one or more functionalised polyolefins is a polyalkylene which includes at
least one
diacid or anhydride functional group. The one or more functionalised
polyolefins is
preferably derived from polymerisation of an olefin, especially a mono-olefin,
having
from 2 to 6 carbon atoms, such as ethene, propene, but-1 -ene and isobutene
(i.e. 2-methyl
propene) and the resulting polyolefin functionaliscd with a diacid or
anhydride functional
group. Preferably, the one or more functionalised polyolefins is a poly(C2 to
C6 alkylene)
functionalised with a diacid or anhydride functional group. Even more
preferably, the
one or more functionalised polyolefins is derived from polymerisation of
isobutene and
the resulting polyisobutylene functionalised with a diacid or anhydride
functional group
(i.e. the functionalised polyolefin is functionalised polyisobutylene).
The polyalkylene part (e.g. the poly(C2 to C6 alkylenc)) of the one or more
functionalised
polyolefins suitably includes a carbon chain of 15 to 500 (e.g. 35 to 500, 40
to 500, 50 to
500), preferably 50 to 200, carbon atoms. Suitably, the polyalkylene part of
the one or
more functionalised polyolefins has a number average molecular weight (Mn) of
from
300 to 5000, preferably 500 to 1500, especially 800 to 1200 daltons.
The functionalised polyolefin(s) includes at least one diacid or anhydride
functional
group which is capable of reacting with a hydroxyl functional group of the
polyethylene
glycol or polypropylene glycol or a mixed poly(ethylene-propylene) glycol
(B(ii)) thereby
forming, via an ester linkage, an essentially polyolefin-polyethylene glycol
copolymer or
polyolefin-polypropylene glycol copolymer or polyolefin-poly(ethylene-
propylene) glycol
copolymer. Accordingly, the functionalised polyolefin(s) may be formed from
reaction of
the polyolefin (i.e. polyalkylene) with an unsaturated diacid or anhydride.
Preferably, the
functionalised polyolefin(s) includes an anhydride functional group. Suitably
the
anhydride functionalised polyalkylene(s) is derived from the reaction of the
polyalkylene
(e.g. poly(C2 to C6 alkylene)) with an anhydride, especially maleic anhydride
which forms
a succinic anhydride functional group. Accordingly, the functionalised
polyolefin(s)
includes an anhydride functional group, especially a succinic anhydride
functional group.
Accordingly, preferred functionalised polyolefin(s) are polyalkylene(s) which
include an
anhydride functional group, more preferably a poly(C2 to C6 alkylene) which
includes an
anhydride functional group, even more preferably a poly(C2 to C6 alkylene)
which includes
a succinic anhydride functional group, especially one or more polyisobutylenes
(PIBs)
which include a succinic anhydride functional group ¨ namely polyisobutylene
succinic
anhydrides (PIBSAs). 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
GlissopalTM by BASF and this product can be reacted to give a functionalised
polyolefin
(B(i)).
Suitably, the functionalised polyolefin(s) which includes a diacid or
anhydride
functional group as defined herein (e.g. a poly(C2 to C6 alkylene) which
includes a diacid
or anhydride functional group, even more preferably a poly(C2 to C6 alkylene)
which
includes a succinic anhydride functional group, especially a polyisobutylene
(PIB) which
includes a succinic anhydride functional group ¨ namely polyisobutylene
succinic
anhydride (PIBSA)) is formed by a direct thermal condensation reaction (i.e.
thermal ene
reaction) between the appropriate unsaturated diacid or anhydride (e.g. maleic
anhydride)
21
Date Recue/Date Received 2021-06-30
CA 02893404 2015-06-02
and the polyolefin (e.g. poly(C2 to C6 alkylene), preferably polyisobutylene
(PIB)). This
process is known as the thermal ene reaction and is usually conducted at a
temperature of
greater than 150 C for 1 to 48 hours. The functionalised polyolefin formed by
the thermal
ene reaction is chemically distinct and has different physical and chemical
properties than
a comparable functionalised polyolefin which is formed by a chlorination
process (i.e.
chlorination of the polyolefin followed by reaction with the appropriate
diacid or
anhydride).
Polyalkylene Glycol (B(ii))
The one or more polyalkylene glycols (B(ii)) used in the formation of the oil-
soluble or
oil-dispersible polymeric friction modifier is selected from one or more
polyethylene
glycols, one or more polypropylene glycols, one or more mixed poly(ethylene-
propylene)
glycols, or combinations thereof. Preferably, the one or more polyalkylene
glycols
(B(ii)) is one or more polyethylene glycols (PEGs), especially a water soluble
PEG.
The polyethylene glycol or polypropylene glycol or mixed poly(ethylene-
propylene)
glycol includes two hydroxyl groups which are capable of reacting with the
functional
group of the functionalised polyolefin, thereby forming an essentially
polyolefin-
polyethylene glycol copolymer or polyolefin-polypropylene glycol copolymer or
polyolefin-poly(ethylene-propylene) glycol copolymer copolymer.
Suitably, the one or more polyalkylenc glycols (B(ii)), namely one or more
polyethylene
.. glycols, one or more polypropylene glycols, or one or more mixed
poly(ethylene-
propylene) glycols, especially 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 one or more polyalkylene glycols (B(ii)) is
PEG400, PEG600
or PEG1000. Suitably, PEG400, PEG600 and PEG1000 are commercially available
from
Croda International.
22
CA 02893404 2015-06-02
As mentioned previously, the functionalised polyolefin and the polyethylene
glycol or
polypropylene glycol or a mixed poly(ethylene-propylene) glycol react to form
a
copolymer. Accordingly, the functionalised polyolefin and the polyethylene
glycol or
polypropylene glycol or mixed poly(ethylene-propylene) glycol 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.
The Monocarboxylic Acid (B(iii))
Suitably the copolymer reaction product of the functionalised polyolefin
(B(i)) and the
polyethylene glycol or polypropylene glycol or a mixed poly(ethylene-
propylene) glycol
(B(ii)) includes a reactive hydroxyl functional group (i.e. a hydroxyl group
associated
with polyethylene glycol or polypropylene glycol or a mixed poly(ethylene-
propylene)
glycol moiety) and such copolymer is reacted with a monocarboxylic acid,
thereby chain
terminating the copolymer product of reaction (i.e. the monocarboxylic acid
reacts with a
hydroxyl functional group associated with a polyethylene glycol or
polypropylene glycol
or a mixed poly(ethylene-propylene) glycol moiety to form an ester, thereby
chain
teiminating the copolymer).
Suitably the one or more monocarboxylic acids is a C2 to C36 hydrocarbyl
monocarboxylic acid, preferably a C6 to C30 hydrocarbyl monocarboxylic acid,
more
preferably a C12 to C22 hydrocarbyl monocarboxylic acid. Even more preferably,
the one
or more monocarboxylic acids is a saturated or unsaturated, branched or
linear, acyclic C2
to C36 aliphatic hydrocarbyl monocarboxylic acid, especially a saturated or
unsaturated,
branched or linear, acyclic C6 to C30 aliphatic hydrocarbyl monocarboxylic
acid, more
especially a saturated or unsaturated, branched or linear, acyclic C12 to C22
aliphatic
hydrocarbyl monocarboxylic acid. Even
more preferably, the one or more
23
CA 02893404 2015-06-02
monocarboxylic acids is an unsaturated acyclic C6 to C30 aliphatic hydrocarbyl
monocarboxylic acid, more especially an unsaturated, acyclic C12 to C22
aliphatic
hydrocarbyl monocarboxylic acid.
In preferred embodiments the carboxylic acid is chosen from the group
comprising lauric
acid, erucic acid, isostearic acid, palmitic acid, tall oil fatty acid, oleic
acid and linoleic
acid, especially oleic acid.
Thus according to a highly preferred embodiment the oil-soluble or oil-
dispersible
polymeric friction modifier (B) is the reaction product of solely:
(i) PIBSA, as defined herein;
(ii) polyethylene glycol, as defined herein; and,
(iii) a monocarboxylic acid, as defined herein, especially oleic acid.
As with all polymers, the polymeric friction modifier (B) 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.
.. 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 mg KOH/g.
Suitably, the polymeric friction modifier (B) may be prepared by analogous
synthetic
methodology as described in International Patent Application no. WO
2011/107739.
Typically, the functionalised polyolefin as defined herein, the polyalkylene
glycol, as
defined herein, and the monocarboxylic acid are heated at 100 to 250 C in the
presence of
.. a catalyst (e.g. tetrabutyl titanate) and water removed.
24
CA 02893404 2015-06-02
In a preferred embodiment the polymeric friction modifier (B) is the reaction
product of
maleinised polyisobutylene (PIBSA), PEG, and oleic acid, wherein the
polyisobutylene
of the maleinised polyisobutylene has a number average molecular weight of
around 950
daltons, the PIBSA has an approximate saponification value of 98mg 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 166.5 g (0.135
mol) of
PIBSA, 135.3 g (0.226 mol) of PEG600 and 34.3 g (0.121 mol) of oleic acid into
a glass
round bottomed flask equipped with a nitrogen purge, mechanical stirrer,
isomantle
heater and overhead condenser. The reaction takes place in the presence of 0.5
ml of
esterification catalyst tetrabutyl titanate at 180-230 'V, with removal of
water to a final
acid value of 1.7 mg KOH/g.
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)
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
CA 02893404 2015-06-02
di(C2 to C8 alkyl) dithiophosphate wherein the C2 to C8 alkyl groups of the
zinc di(C2 to
C8 alkyl) dithiophosphate may be the same or different.
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 P2S5 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.
The preferred zinc dihydrocarbyl dithiophosphates (ZDDP) are oil-soluble salts
of
dihydrocarbyl dithiophosphoric acids and may be represented by the following
formula:
ROM
\
S Zn
R'0 ¨2
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.
26
CA 02893404 2015-06-02
R and R') in the dithiophosphoric acid will generally be about 5 or greater.
The zinc
dihydrocarbyl dithiophosphate can therefore comprise zinc dialkyl
dithiophosphates.
The dihydrocarbyl dithiophosphate metal salt, such as ZDDP, is added to the
lubricating
.. oil compositions in amounts sufficient to provide no greater than 1200ppm,
preferably no
greater than 1000ppm, more preferably no greater than 900ppm, most preferably
no
greater than 850ppm 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 dihydrocarbyl dithiophosphate metal salt, such as ZDDP, is suitably
added
to the lubricating oil compositions in amounts sufficient to provide at least
100ppm,
preferably at least 350ppm, more preferably at least 500ppm 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.
Suitably, the dihydrocarbyl dithiophosphate metal salt, such as ZDDP, is
present in an
amount of greater than or equal to 0.1, preferably greater than or equal to
0.25, more
preferably greater than or equal to 0.5, mass % based on the total mass of the
lubricating
oil composition. Suitably, the dihydrocarbyl dithiophosphate metal salt, such
as ZDDP,
is present in an amount of less than or equal to 10, preferably less than or
equal to 5.0,
.. more preferably less than or equal to 3.0, mass % based on the total mass
of the
lubricating oil composition.
ENGINES
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
27
CA 02893404 2015-06-02
engines may be specifically modified to be powered by an alcohol based fuel or
biodiesel
fuel.
CO-ADDITIVES
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.
Additive Mass "A) Mass ".70
(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.
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.
28
CA 02893404 2015-06-02
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, demulsitiers, antifoam agents and viscosity
modifiers.
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.
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.
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.,
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CA 02893404 2015-06-02
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.
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.
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, carboxylatc, 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.
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
CA 02893404 2015-06-02
generally mixtures of compounds in which 2 or more phenols are bridged by
sulfur
containing bridges.
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.
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.
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.
Friction modifiers include glycerol monoesters of higher fatty acids, for
example,
glycerol mono-oleatc (GM0); esters of long chain polycarboxylic acids with
diols, for
31
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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.
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.
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.
One class of preferred organo-molybdenum compounds useful in all aspects of
the present
invention is tri-nuclear molybdenum compounds of the formula Mo3SkLQ, 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.
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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.
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.
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.
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.
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
33
CA 02893404 2015-06-02
and mixtures thereof. In a preferred embodiment, an antioxidant is present in
a
lubricating oil composition of the present invention.
Rust inhibitors selected from the group consisting of nonionic polyoxyalkylene
polyols and
esters thereof, polyoxyalkylene phenols, and anionic alkyl sulfonie acids may
be used.
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. Patent
Nos. 2,719,125;
2,719,126; and 3,087,932; are typical. Other similar materials are described
in U.S. Patent
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.
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.
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 C8 to
C18 dialkyl fumarate/vinyl acetate copolymers, polyalkylmethacrylates and the
like.
34
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Foam control can be provided by many compounds including an antifoamant of the
polysiloxane type, for example, silicone oil or polydimethyl siloxane.
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.
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.
The concentrate is preferably made in accordance with the method described in
US
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 C.
Thereafter, the pre-
mix is cooled to at least 85 C and the additional components are added.
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.
CA 02893404 2015-06-02
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.
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.
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
The invention will now be described in the following examples which are not
intended to
limit the scope of the claims hereof.
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)
A 500 cm3 5-necked round-bottomed flask equipped with a nitrogen purge,
stirrer with
PTFE guide, temperature probe and distillation arm attached to an exit bubbler
was
charged with PIBSA (116.5 g, 0.135 mol), PEG600 (135.3 g, 0.226 mol) and oleic
acid
(34.3 g, 0.121 mol) and the mixture heated at 180 C with stirring for 1 hour.
The
reaction mixture was then heated to a temperature of 230 C for 1 hour and then
tetrabutyl
titanate (0.5 ml) added thereto and heating and stirring continued for 6 hours
at a
.. temperature of 230 C. The reaction mixture was cooled to below 100 C and
the
36
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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
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 880ppm as
measured by
ASTM D5185. Oil 5 represents a lubricating oil composition of the present
invention.
Table 1
Component Base Oil 1 Oil 2 Oil 3 Oil 4
Oil 5
lubricant Mass% Mass% Mass% Mass% Mass%
ZDDP 1.10
1.10 1.10
Polymeric friction modifier 0.50 0.50
(B)1
Glycerol monooleate 0.50 0.50
1 The polymeric friction modifier was the compound of Example I.
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.
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
37
CA 02893404 2015-06-02
tube is immersed in a heated oil bath so that the temperature of the test
lubricating oil is
heated to 135 C. The test lubricating oil is heated at 135 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 2
Corrosion Base Oil 1 Oil 2 Oil 3 Oil 4 Oil 5
lubricant
Lead (ppm) 23 8 403 63 420 115
Copper (ppm) 33 27 49 27 22 10
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
(13)
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
(27 ppm
versus 33 ppm) and lead (8ppm 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.
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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 (420ppm 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 (115 ppm versus 420 ppm) and the polymeric
friction
modifier is far superior than the ashless organic friction modifier at
inhibiting copper
corrosion (10 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 (10 ppm
versus 33 ppm).
39
