Note: Descriptions are shown in the official language in which they were submitted.
BENZOTRIAZOLE DERIVATIVE AND MOLYBDENUM DITHIOCARBAMATE-
CONTAINING LUBRICATING OIL COMPOSITIONS FOR FRICTION
REDUCTION AND FUEL CONSUMPTION REDUCTION
FIELD OF THE INVENTION
The present invention relates to automotive engine lubricating oils, which
exhibit
improved friction reduction and fuel consumption reduction, especially at
lower operating
temperatures, in particular at engine operating temperatures below 80 C.
BACKGROUND OF THE INVENTION
It is well known that molybdenum containing additives can be used in
automotive
engine lubricants to improve friction reduction performance. However, it has
generally been
found that the efficacy of such additives is not realized until the engine
temperature reaches
around 80 C. Thus, when an engine is operating at temperatures below 80 C
the excellent
friction reducing properties of molybdenum-containing additives is not
exhibited.
Benzotriazole compounds have been used for many years in lubricating oil
compositions as corrosion inhibitors to reduce copper corrosion.
It is the object of the present invention to further improve the friction and
fuel
economy performance of automotive engine lubricating oils.
SUMMARY OF THE INVENTION
According to a first aspect the present invention provides an automotive
engine
lubricating oil composition comprising
(A) a base oil of lubricating viscosity,
(B) at least one benzotriazole derivative represented by Formula (I):
R5
\CH2 ____________________________________________ R6
Formula (I)
1
Date recue/Date received 2023-05-19
wherein R5 is a hydrocarbyl group having 1-3 carbon atoms and R6 is a tertiary
amine group
represented by
R7
_______________________________________ N
R8
wherein R7 and R8 are independently, linear or branched, hydrocarbyl groups
having 3 to 10
carbon atoms,
(C) at least one molybdenum dithiocarbamate compound represented by either
Formula (II)
or Formula (III):
R S I X X4
r II / 2\11 /S R3\
N ¨ C / Mo Mo ,C ¨N
,
\
rk2 X3 R4
Formula (II)
wherein R1 through R4 independently denote a straight chain, branched chain or
aromatic
hydrocarbyl group having 1 to 24 carbon atoms; and X1 through X4 independently
denote an
oxygen atom or a sulfur atom,
Formula (III)
Mo3SkLnQz
wherein L are independently selected ligands having organo groups with a
sufficient number
of carbon atoms to render the compound soluble or dispersible in the oil, n is
from 1 to 4, k is
from 4 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, and
(D) one or more additional additives chosen from metal containing or ashless
detergents,
ashless antioxidants, antiwear additives, corrosion inhibitors, rust
inhibitors, viscosity index
improvers, and dispersants,
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wherein the lubricating oil composition comprises a total amount of from 100
to 2000 ppm
molybdenum from components (C) and wherein the benzotriazole derivative (B) is
present in
the lubricating oil in an amount from 0.001 to 5 mass%.
Preferably, the base oil of lubricating viscosity (A) is present in a major
amount.
Preferably, the automotive engine lubricating oil composition of the present
invention
is used to lubricate the crankcase of the engine (i.e. an automotive engine
crankcase lubricant).
Suitably, the automotive engine lubricating oil composition is used to
lubricate an
automotive spark-ignited or automotive compression-ignited internal combustion
engine,
preferably an automotive spark-ignited internal combustion engine.
Unexpectedly, it has been found that the use of the benzotriazole compound as
an
additive in a lubricating oil composition which includes a molybdenum
containing additive,
especially a molybdenum dithiocarbamate compound, permits improved friction
reduction
performance, particularly boundary regime friction reduction performance, of
the molybdenum
containing additive when the lubricating oil composition is used to lubricate
an automotive
engine. Furthermore, the improved friction reduction performance of the
molybdenum
containing compound is realized at lower engine operating temperatures i.e.
when the engine is
operating at temperatures below 80 C. Accordingly, the automotive engine
lubricating oil
composition of the present inventions provides benefits in terms of improved
friction
reduction and/or improved fuel consumption reduction.
In accordance with a second aspect, the present invention provides a method of
lubricating an automotive engine comprising lubricating the engine with a
lubricating oil
composition as defined in accordance with the first aspect of the present
invention. Suitably,
the method comprises lubricating the crankcase of the engine.
In accordance with a third aspect, the present invention provides the use, in
the
lubrication of an automotive engine, of at least one benzotriazole derivative
(B), as defined in
the first aspect of the invention, as an additive in an effective minor
amount, in a lubricating
oil composition comprising a base oil of lubricating viscosity (A) and at
least one
molybdenum dithiocarbamate compound (C), as defined in the first aspect of the
invention,
to improve the friction reducing performance properties of the molybdenum
dithiocarbamate
compound(s) (C) during operation of the automotive engine, wherein said
molybdenum
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dithiocarbamate compound(s) (C) provide the lubricating oil composition with
from 100 to
2000 ppm of molybdenum.
In accordance with a fourth aspect, the present invention provides the use, in
the
lubrication of an automotive engine, of the combination of at least one
benzotriazole derivative
(B), as defined in the first aspect of the invention, and at least one
molybdenum
dithiocarbamate compound (C), as defined in the first aspect of the invention,
as a
combination of additives in an effective minor amount, in a lubricating oil
composition
comprising a base oil of lubricating viscosity (A), to improve friction
reduction of the
lubricating oil composition during operation of the automotive engine, wherein
said
molybdenum dithiocarbamate compound(s) (C) provide the lubricating oil
composition with
from 100 to 2000 ppm of molybdenum.
In accordance with a fifth aspect, the present invention provides the use, in
the
lubrication of an automotive engine, of the combination of at least one
benzotriazole derivative
(B), as defined in the first aspect of the invention, and at least one
molybdenum
dithiocarbamate compound (C), as defined in the first aspect of the invention,
as a
combination of additives in an effective minor amount, in a lubricating oil
composition
comprising a base oil of lubricating viscosity (A), to reduce fuel consumption
of the
automotive engine during operation of the engine, wherein said molybdenum
dithiocarbamate compound(s) (C) provide the lubricating oil composition with
from 100 to
2000 ppm of molybdenum.
Preferably, the automotive engine in the second to fifth aspects of the
invention
operates at temperatures below 80 C.
Preferably, the lubricating oil composition as defined in the third, fourth
and fifth
aspects of the present invention further includes (D) one or more additional
additives chosen
from metal containing or ashless detergents, ashless antioxidants, antiwear
additives, corrosion
inhibitors, rust inhibitors, viscosity index improvers, and dispersants.
Suitably, the engine as defined in the second, third, fourth and fifth aspects
of the
present invention is a spark-ignited or compression-ignited internal
combustion engine,
preferably a spark-ignited internal combustion engine.
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Suitably, the at least one benzotriazole derivative (B) is present, in the
lubricating oil
composition of the first aspect of the invention and the lubricating oil
composition as defined
in the second to fifth aspects of the invention, in an amount of from 0.001 to
5 mass %,
preferably in an amount of 0.01 to 2 mass %, more preferably in an amount of
0.01 to 1
mass %, even more preferably in an amount of 0.01 to 0.04 mass % on an active
matter basis.
Suitably, the at least one molybdenum dithiocarbamate compound (C) provides
the
lubricating oil composition of the first aspect of the invention, and the
lubricating oil
composition as defined in the second to fifth aspects of the invention, with a
total amount of
100 to 2000, preferably 450 to 2000, more preferably 450 to 1200, even more
preferably 450
to 900, most preferably 600 to 900, ppm molybdenum (ASTM D5185).
Suitably, 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.
Preferably, the lubricating oil composition of the present invention contains
low
levels of phosphorus. Suitably, the lubricating oil composition contains
phosphorus in an
amount of less than or equal to 0.12, preferably up to 0.11, more preferably
less than or equal
to 0.10, even more preferably less than or equal to 0.09, even more preferably
less than or
equal to 0.08, 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 may contain low levels of sulphur.
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.
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Suitably, the lubricating oil composition may have a total base number (TBN),
as
measured in accordance with ASTM D2896, of from 4 to 15, preferably from 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 "(al.)" refers to additive material that is not
diluent or solvent;
"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", "ally!"
and
"aryl" as defined herein;
"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,
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hexyl, heptyl, octyl, dimethyl hexyl, nonyl, decyl, undecyl, dodecyl,
tridecyl,
tetradecyl, pentadecyl, hexadecyl, heptadecyl, octadecyl, nonadecyl, icosyl
and
triacontyl;
"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";
"alkylene" means a C2 to C20, preferably a C2 to C io, more preferably a C2 to
C6
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-ethy1-2-methyl ethylene, 1,1-dimethyl ethylene
and
1-ethyl propylene;
"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;
"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;
"halo" or "halogen" includes fluoro, chloro, bromo and iodo;
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"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;
"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 an amount of such an
additive in a lubricating oil composition so that the additive provides the
desired
technical effect;
"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 detergent metal, molybdenum or boron content or total metal content of
the
lubricating oil composition (i.e. the sum of all individual metal contents),
is measured
by ASTM D5185;
"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;
"KVioo" means kinematic viscosity at 100 C as measured by ASTM D445;
"phosphorus content" is measured by ASTM D5185;
"sulfur content" is measured by ASTM D2622; and,
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"sulfated ash content" is measured by ASTM D874.
All percentages reported are mass $3/0 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.
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
OIL OF LUBRICATING VISCOSITY
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:
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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).
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
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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, 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 Cs 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
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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
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.
Preferably, the oil of lubricating viscosity is present in an amount of
greater than 55
mass %, more preferably greater than 60 mass %, even more preferably greater
than 70
mass %, based on the total mass of the lubricating oil composition.
Preferably, the oil of
lubricating viscosity is present in an amount of less than 98 mass %, more
preferably less
than 95 mass %, even more preferably less than 90 mass %, based on the total
mass of the
lubricating oil composition.
The lubricating oil composition of each aspect of the present invention may be
a
multigrade oil identified by the viscometric descriptor SAE 20W-X, SAE 15W-X,
SAE
10W-X, SAE 5W-X or SAE OW-X, where X represents any one of 8, 12, 16, 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 10W-X,
SAE 5W-X
or SAE OW-X, preferably in the form of a SAE OW-X or SAE 5W-X viscosity grade,
wherein X represents any one of 8, 12, 16, 20 or 30. Preferably X is 8, 12, 16
or 20.
BENZOTRIAZOLE DERIVATIVE (B)
The lubricating oil composition of the present invention comprises at least
one
benzotriazole derivative represented by Formula (I):
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R5
N
CH2 --R6
Formula (I)
wherein R5 is a hydrocarbyl group having 1-3 carbon atoms and R6 is a tertiary
amine group
represented by
R7
_____________________________________ N
R8
wherein R7 and R8 are independently, linear or branched, hydrocarbyl groups
having 3 to 10
carbon atoms.
In a preferred embodiment R5 is a methyl group. Preferably, R7 and R8 are both
the
same. In a preferred embodiment, R7 and R8 are hydrocarbyl groups having 6 to
8 carbon
atoms.
In a preferred embodiment, the benzotriazole derivative has the following
structure:
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CH3
N
CH2
C2H5
_CH24H9
H2C
C2H 5
C4H9
Suitably the benzotriazole derivative is present in the lubricating oil
composition of
the present invention in an amount from 0.001 to 5 wt%, preferably in an
amount of 0.01 to
2 wt% for example, in an amount of 0.01 to 1 wt% on an active matter basis. In
a preferred
embodiment, the benzotriazole derivative is present in the lubricating oil
composition of the
present invention in an amount of 0.01 to 0.04 wt% on an active matter basis.
OIL-SOLUBLE MOLYBDENUM COMPOUND (C)
Suitable dinuclear or dimeric molybdenum dialkyldithiocarbamate compounds are
represented by the Formula (II):
RI Xi x
\ II / 2\i(14
s/S /R3
N C ; Mo Mo _N
/ \R4
R2
X3
wherein R1 through R4 independently denote a straight chain, branched chain or
aromatic
hydrocarbyl group having 1 to 24 carbon atoms; and X1 through X4 independently
denote an
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oxygen atom or a sulfur atom. The four hydrocarbyl groups, Ri through R4, may
be identical
or different from one another.
Suitable tri-nuclear organo-molybdenum compounds include those of the formula
Mo3SkLnQz and mixtures thereof wherein L are independently selected ligands
having organo
groups with a sufficient number of carbon atoms to render the compound soluble
or dispersible
in the oil, n is from 1 to 4, k varies from 4 through 7, Q is selected from
the group of neutral
electron donating compounds such as water, amines, alcohols, phosphines, and
ethers, and z
ranges from 0 to 5 and includes non-stoichiometric values. At least 21 total
carbon atoms should
be present among all the ligands' organo groups, such as at least 25, at least
30, or at least 35
carbon atoms.
The ligands are independently selected from the group of:
¨X¨ R 1,
xl
R 2,
X2
XIN
X/
and mixtures thereof, wherein X, Xi, X2, and Y are independently selected from
the group of
oxygen and sulfur, and wherein RI, R2, and R are independently selected from
hydrogen and
organo groups that may be the same or different. Preferably, the organo groups
are hydrocarbyl
groups such as alkyl (e.g., in which the carbon atom attached to the remainder
of the ligand is
primary or secondary), aryl, substituted aryl and ether groups. More
preferably, each ligand
has the same hydrocarbyl group.
Importantly, the organo groups of the ligands have a sufficient number of
carbon atoms
to render the compound soluble or dispersible in the oil. For example, the
number of carbon
atoms in each group will generally range between about 1 to about 100,
preferably from about
1 to about 30, and more preferably between about 4 to about 20. Preferred
ligands include
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dialkyldithiophosphate, alkylxanthate, and dialkyldithiocarbamate, and of
these
diallcyldithiocarbamate is more preferred. Organic ligands containing two or
more of the above
functionalities are also capable of serving as ligands and binding to one or
more of the cores.
Those skilled in the art will realize that formation of the compounds of the
present invention
requires selection of ligands having the appropriate charge to balance the
core's charge.
Compounds having the formula Mo3SkLnQz have cationic cores surrounded by
anionic
ligands and are represented by structures such as
100')T
/
and
1111 ,43
181/
moV, >0
and have net charges of +4. Consequently, in order to solubilize these cores
the total charge
among all the ligands must be -4. Four mono-anionic ligands are preferred.
Without wishing
to be bound by any theory, it is believed that two or more tri-nuclear cores
may be bound or
interconnected by means of one or more ligands and the ligands may be
multidentate. This
includes the case of a multidentate ligand having multiple connections to a
single core. It is
believed that oxygen and/or selenium may be substituted for sulfur in the
core(s).
Oil-soluble or oil-dispersible tri-nuclear molybdenum compounds can be
prepared by
reacting in the appropriate liquid(s)/solvent(s) a molybdenum source such as
(NF14)2Mo3S13.n(1120), where n varies between 0 and 2 and includes non-
stoichiometric values,
16
CA 3038157 2019-03-27
with a suitable ligand source such as a tetralkylthiuram disulfide. Other oil-
soluble or
dispersible tri-nuclear molybdenum compounds can be formed during a reaction
in the
appropriate solvent(s) of a molybdenum source such as of (NF14)2M03S13.n(H20),
a ligand
source such as tetralkylthiuram disulfide, diallcyldithiocarbamate, or
dialkyldithiophosphate,
and a sulfur abstracting agent such as cyanide ions, sulfite ions, or
substituted phosphines.
Alternatively, a tri-nuclear molybdenum-sulfur halide salt such as
[M]2[Mo3S7A6], where M'
is a counter ion, and A is a halogen such as Cl, Br, or I, may be reacted with
a ligand source
such as a dialkyldithiocarbamate or diallcyldithiophosphate in the appropriate
liquid(s)/solvent(s) to form an oil-soluble or dispersible trinuclear
molybdenum compound.
.. The appropriate liquid/solvent may be, for example, aqueous or organic.
A compound's oil solubility or dispersibility may be influenced by the number
of
carbon atoms in the ligand's organo groups. Preferably, at least 21 total
carbon atoms should
be present among all the ligands' organo groups. Preferably, the ligand source
chosen has a
sufficient number of carbon atoms in its organo groups to render the compound
soluble or
dispersible in the lubricating composition.
The lubricating oil composition of the present invention may comprise either a
dimeric or trimeric molybdenum compound or both.
The total amount of oil-soluble molybdenum dithiocarbamate compounds will
depend upon the particular performance requirements of the lubricating oil
composition.
Suitably, the lubricating oil composition of the present invention contains a
total amount of
molybdenum dithiocarbamate compounds in an amount providing the composition
with at
least 100ppm, or at least 200ppm, or at least 300ppm, or at least 400ppm, or
at least 450ppm
of molybdenum (as measured according to ASTM D5185). The lubricating oil
composition
of all aspects of the present invention may contain the molybdenum compound in
an amount
providing the composition with up to 2000 ppm, or up to 1500ppm or up to
1200ppm, or up
to 800 ppm of molybdenum (as measured according to ASTM D5185). In a preferred
embodiment the molybdenum dithiocarbamate compound (C) provides the
lubricating oil
composition with from 600 to 900 ppm molybdenum.
Preferably, the dimeric molybdenum dithiocarbamate and/or the trimeric
molybdenum
dithiocarbamate are the sole sources of molybdenum atoms in the lubricating
oil composition.
17
CA 3038157 2019-03-27
In a preferred embodiment the lubricating oil composition comprises both
dimeric
and trimeric oil soluble molybdenum dithiocarbamate.
ADDITIONAL ADDITIVES (D)
The lubricating oil of all aspects of the present invention may also comprise
one or
more additional conventional additives, including, but not limited to metal
containing or
ashless detergent, ashless antioxidant, antiwear additives, corrosion
inhibitors, rust
inhibitors, viscosity index improvers and dispersants.
In a preferred embodiment the lubricating oil compositions of the present
invention
include an aminic friction modifier having a structure according to Formula
(IV) below:
74137
,0
OH N OH
Formula (IV)
Typically, the total amount of aminic friction modifier of Formula (IV) in the
lubricating oil composition of all aspects of the present invention does not
exceed 5 mass %,
based on the total mass of the lubricating oil composition and preferably does
not exceed 2
mass % and more preferably does not exceed 0.5 mass %. Preferably, the aminic
friction
modifier of Formula (IV) is present, in the lubricating oil composition of all
aspects of the
present invention, in an amount of from 0.1 to 1.0, more preferably 0.1 to
0.5, even more
preferably 0.1 to 0.3, mass %.
Dispersants are additives whose primary function is to hold solid and liquid
contaminations in suspension, thereby passivating them and reducing engine
deposits at the
18
CA 3038157 2019-03-27
same time as reducing sludge depositions. For example, a dispersant maintains
in suspension
oil-insoluble substances that result from oxidation during use of the
lubricant, thus
preventing sludge flocculation and precipitation or deposition on metal parts
of the engine.
Dispersants are usually "ashless", being non-metallic organic materials that
form
substantially no ash on combustion, in contrast to metal-containing, and hence
ash-forming
materials. They comprise a long hydrocarbon chain with a polar head, the
polarity being
derived from inclusion of e.g. an 0, P, or N atom. The hydrocarbon is an
oleophilic group
that confers oil-solubility, having, for example 40 to 500 carbon atoms. Thus,
ashless
dispersants may comprise an oil-soluble polymeric backbone.
The ashless dispersant suitable for all aspects of the present invention is
preferably
an ashless, nitrogen-containing dispersant.
Suitable ashless dispersant may be made from polyalkenes that have been
functionalised exclusively by the thermal "ene" reaction, a known reaction.
Such
polyalkenes are mixtures having predominantly terminal vinylidene groups, such
at least 65,
e.g. 70, more preferably at least 85, %. As an example, there may be mentioned
a polyalkene
known as highly reactive polyisobutene (HR-PIB), which is commercially
available under
the tradename GlissopalTM (ex BASF). US-A-4 152 499 describes the preparations
of such
polymers.
Alternatively, the ashless dispersant may be made from polyalkenes that have
been
functionalised by the so-called chlorination method, which results in a
product where minor
percentage of its polymer chains (e.g. less than 20%) have terminal vinylidene
groups.
Preferred monounsaturated reactants that may be used to functionalize the
polyalkene comprise mono- and dicarboxylic acid material, i.e., acid,
anhydride, or acid ester
material, including (i) monounsaturated C4 to C10 dicarboxylic acid wherein
(a) the carboxyl
groups are vicinyl, (i.e., located on adjacent carbon atoms) and (b) at least
one, preferably
both, of said adjacent carbon atoms are part of said mono unsaturation; (ii)
derivatives of (i)
such as anhydrides or C1 to C5 alcohol derived mono- or diesters of (i); (iii)
monounsaturated
C3 to CIO monocarboxylic acid wherein the carbon-carbon double bond is
conjugated with
the carboxy group, i.e., of the structure -C=C-00-; and (iv) derivatives of
(iii) such as C1 to
C5 alcohol derived mono- or diesters of (iii). Mixtures of monounsaturated
carboxylic
19
CA 3038157 2019-03-27
materials (i) - (iv) also may be used. Upon reaction with the polyalkene, the
monounsaturation of the monounsaturated carboxylic reactant becomes saturated.
Thus, for
example, maleic anhydride becomes polyalkene-substituted succinic anhydride,
and acrylic
acid becomes polyalkene-substituted propionic acid. Exemplary of such
monounsaturated
carboxylic reactants are fumaric acid, itaconic acid, maleic acid, maleic
anhydride, acrylic
acid, methacrylic acid, crotonic acid, cinnamic acid, and lower alkyl (e.g.,
Ci to C4 alkyl)
acid esters of the foregoing, e.g., methyl maleate, ethyl fumarate, and methyl
finnarate.
To provide the required functionality, monounsaturated carboxylic reactants,
preferably maleic anhydride, typically will be used in an amount ranging from
equimolar to
100, preferably 5 to 50, wt. % excess, based on the moles of polyalkene.
Unreacted excess
monounsaturated carboxylic reactant can be removed from the final dispersant
product by,
for example, stripping, usually under vacuum, if required.
The functionalised oil-soluble polyalkene is then derivatized with a
nucleophilic
reactant, such as an amine, amino-alcohol, alcohol, or mixture thereof, to
form a
corresponding derivative containing the dispersant. Useful amine compounds for
derivatizing functionalized polymers comprise at least one amine and can
comprise one or
more additional amine or other reactive or polar groups. These amines may be
hydrocarbyl
amines or may be predominantly hydrocarbyl amines in which the hydrocarbyl
group
includes other groups, e.g., hydroxy groups, alkoxy groups, amide groups,
nitriles and
imidazoline groups. Particularly useful amine compounds include mono- and
polyamines,
e.g., polyalkene and polyoxyalkylene polyamines of 2 to 60, such as 2 to 40
(e.g., 3 to 20),
total carbon atoms having 1 to 12, such as 3 to 12, preferably 3 to 9, most
preferably 6 to 7,
nitrogen atoms per molecule. Mixtures of amine compounds may advantageously be
used.
Preferred amines are aliphatic saturated amines, including, for example, 1,2-
diaminoethane;
1,3-diaminopropane; 1,4-diaminobutane; 1,6-diaminohexane; polyethylene amines
such as
diethylene triamine; triethylene tetramine; tetraethylene pentamine; and
polypropyleneamines such as 1,2-propylene diamine; and di-(1,2-
propylene)triamine. Such
polyamine mixtures, known as PAM, are commercially available. Particularly
preferred
polyamine mixtures are mixtures derived by distilling the light ends from PAM
products.
The resulting mixtures, known as "heavy" PAM, or HPAM, are also commercially
available.
CA 3038157 2019-03-27
The properties and attributes of both PAM and/or HPAM are described, for
example, in U.S.
Patent Nos. 4,938,881; 4,927,551; 5,230,714; 5,241,003; 5,565,128; 5,756,431;
5,792,730;
and 5,854,186.
Other useful amine compounds include: alicyclic diamines such as
1,4-di(aminomethyl) cyclohexane and heterocyclic nitrogen compounds such as
imidazolines. Another useful class of amines is the polyamido and related
amido-amines as
disclosed in U.S. Patent Nos. 4,857,217; 4,956,107; 4,963,275; and 5,229,022.
Also usable
is tris(hydroxymethyl)amino methane (TAM) as described in U.S. Patent Nos.
4,102,798;
4,113,639; 4,116,876; and UK 989,409. Dendrimers, star-like amines, and comb-
structured
amines may also be used. Similarly, condensed amines, as described in U.S.
Patent No.
5,053,152 may be used. The fiinctionalized polymer is reacted with the amine
compound
using conventional techniques as described, for example, in U.S. Patent Nos.
4,234,435 and
5,229,022, as well as in EP-A-208,560.
A dispersant of the present invention preferably comprises at least one
dispersant that
is derived from polyalkenyl-substituted mono- or dicarboxylic acid, anhydride
or ester,
which has from greater than 1.3 to 1.7, preferably from greater than 1.3 to
1.6, most
preferably from greater than 1.3 to 1.5, functional groups (mono- or
dicarboxylic acid
producing moieties) per polyalkenyl moiety (a medium functionality
dispersant).
Functionality (F) can be determined according to the following formula:
F = (SAP x Mn)/((112,200 x A.I.) - (SAP x MW)) (1)
wherein SAP is the saponification number (i.e., the number of milligrams of
KOH consumed
in the complete neutralization of the acid groups in one grain of the succinic-
containing
reaction product, as determined according to ASTM D94); Mn is the number
average
molecular weight of the starting olefin polymer; A.I. is the percent active
ingredient of the
succinic-containing reaction product (the remainder being unreacted olefin
polymer,
succinic anhydride and diluent); and MW is the molecular weight of the mono-
or
dicarboxylic acid producing moieties (e.g., 98 for maleic anhydride).
Generally, each mono- or dicarboxylic acid-producing moiety will react with a
nucleophilic group (amine, alcohol, amide or ester polar moieties) and the
number of
21
CA 3038157 2019-03-27
functional groups in the polyalkenyl-substituted carboxylic acylating agent
will determine
the number of nucleophilic groups in the finished dispersant.
The polyalkenyl moiety of the dispersant of the present invention may have a
number
average molecular weight of at least 900, suitably at least 1500, preferably
between 1800
and 3000, such as between 2000 and 2800, more preferably from about 2100 to
2500, and
most preferably from about 2200 to about 2400. The molecular weight of a
dispersant is
generally expressed in terms of the molecular weight of the polyalkenyl
moiety; this is
because the precise molecular weight range of the dispersant depends on
numerous
parameters including the type of polymer used to derive the dispersant, the
number of
functional groups, and the type of nucleophilic group employed.
Polymer molecular weight, specifically Me , can be determined by various known
techniques. One convenient method is gel permeation chromatography (GPC),
which
additionally provides molecular weight distribution information (see W. W.
Yau, J. J.
Kirkland and D. D. Bly, "Modern Size Exclusion Liquid Chromatography", John
Wiley and
Sons, New York, 1979). Another useful method for determining molecular weight,
particularly for lower molecular weight polymers, is vapor pressure osmometry
(see, e.g.,
ASTM D3592).
The polyalkenyl moiety in a dispersant of the present invention preferably has
a
narrow molecular weight distribution (MWD), also referred to as
polydispersity, as
determined by the ratio of weight average molecular weight (Mw) to number
average
molecular weight (Me). Polymers having a Mw/Me of less than 2.2, preferably
less than 2.0,
are most desirable. Suitable polymers have a polydispersity of from about 1.5
to 2.1,
preferably from about 1.6 to about 1.8.
Suitable polyalkenes employed in the formation of the dispersants of the
present
invention include homopolymers, interpolymers or lower molecular weight
hydrocarbons.
One family of such polymers comprise polymers of ethylene and/or at least one
C3 to C28
alpha-olefin having the formula H2C=CHR1 wherein RI is a straight or branched
chain alkyl
radical comprising 1 to 26 carbon atoms and wherein the polymer contains
carbon-to-carbon
unsaturation, and a high degree of terminal ethenylidene unsaturation.
Preferably, such
polymers comprise interpolymers of ethylene and at least one alpha-olefin of
the above
22
CA 3038157 2019-03-27
formula, wherein RI is alkyl of from 1 to 18 carbon atoms, and more preferably
is alkyl of
from 1 to 8 carbon atoms, and more preferably still of from 1 to 2 carbon
atoms
Another useful class of polymers is polymers prepared by cationic
polymerization of
monomers such as isobutene and styrene. Common polymers from this class
include
polyisobutenes obtained by polymerization of a C4 refinery stream having a
butene content
of 35 to 75% by wt., and an isobutene content of 30 to 60% by wt., by the
thermal "ene"
reaction. A preferred source of monomer for making poly-n-butenes is petroleum
feedstreams such as Raffinate II. These feedstocks are disclosed in the art
such as in U.S.
Patent No. 4,952,739. A preferred embodiment utilizes polyisobutylene prepared
from a
pure isobutylene stream or a Raffinate I stream to prepare reactive
isobutylene polymers
with terminal vinylidene olefins as described above.
The dispersant(s) of the invention are preferably mono- or bis-succinimides.
The dispersant(s) of the present invention can be borated by conventional
means, as
generally taught in U.S. Patent Nos. 3,087,936, 3,254,025 and 5,430,105.
Boration of the
dispersant is readily accomplished by treating an acyl nitrogen-containing
dispersant with a
boron compound such as boron oxide, boron halide boron acids, and esters of
boron acids,
in an amount sufficient to provide from 0.1 to 20 atomic proportions of boron
for each mole
of acylated nitrogen composition.
The boron, which appears in the product as dehydrated boric acid polymers
(primarily (HB02)3), is believed to attach, for example, to dispersant imides
and diimides as
amine salts, e.g., the metaborate salt of the diimide. Boration can be carried
out by adding
a sufficient quantity of a boron compound, preferably boric acid, usually as a
slurry, to the
acyl nitrogen compound and heating with stirring at from 135C to 190, e.g.,
140 to 170, C,
for from 1 to 5 hours, followed by nitrogen stripping. Alternatively, the
boron treatment can
be conducted by adding boric acid to a hot reaction mixture of the
dicarboxylic acid material
and amine, while removing water. Other post-reaction processes known in the
art can also
be applied.
Typically, the lubricating oil composition may contain from 1 to 20, such as 1
to 15,
preferably 1 to 10, mass %, more preferably from 2 to 5 mass% dispersant.
23
CA 3038157 2019-03-27
In a preferred embodiment the lubricating oil composition of the present
invention
comprises from 200-500 ppm boron from a borated dispersant.
Metal-containing detergents function both as detergents to reduce or remove
deposits
and as acid neutralizers or rust inhibitors, thereby reducing wear and
corrosion and extending
engine life. Detergents generally comprise a polar head with a long
hydrophobic tail, with
the polar head comprising a metal salt of an acidic organic compound. The
salts may contain
a substantially stoichiometric amount of the metal in which case they are
usually described
as normal or neutral salts, and would typically have a total base number or
TBN (as can be
measured by ASTM D2896) of from 0 to 80 mg KOH/g. A large amount of a metal
base
may be incorporated by reacting excess metal compound (e.g., an oxide or
hydroxide) with
an acidic gas (e.g., carbon dioxide). The resulting overbased detergent
comprises neutralized
detergent as the outer layer of a metal base (e.g. carbonate) micelle. Such
overbased
detergents may have a TBN of 150 mg KOH/g or greater, and typically will have
a TBN of
from 250 to 450 mg KOH/g or more. In the presence of the compounds of Formula
I, the
amount of overbased detergent can be reduced, or detergents having reduced
levels of
overbasing (e.g., detergents having a 113N 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.
Suitably the lubricating oil composition of the present invention further
comprises at
least one metal-containing detergent additive.
Detergents that may be used include oil-soluble neutral and overbased
sulfonates,
phenates, sulfurized phenates, thiophosphonates, salicylates, and naphthenates
and other oil-
soluble carboxylates of a metal, particularly the alkali or alkaline earth
metals, e.g., sodium,
potassium, lithium, calcium, and magnesium. The most commonly used metals are
calcium
and magnesium, which may both be present in detergents used in a lubricating
oil
composition according to any aspect of the present invention. Combinations of
detergents,
whether overbased or neutral or both, may be used.
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
24
CA 3038157 2019-03-27
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.
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.
Carboxylate detergents, e.g., salicylates, can be prepared by reacting an
aromatic
carboxylic acid with an appropriate metal compound such as an oxide or
hydroxide and
neutral or overbased products may be obtained by methods well known in the
art. The
aromatic moiety of the aromatic carboxylic acid can contain heteroatoms, such
as nitrogen
and oxygen. Preferably, the moiety contains only carbon atoms; more preferably
the moiety
contains six or more carbon atoms; for example benzene is a preferred moiety.
The aromatic
carboxylic acid may contain one or more aromatic moieties, such as one or more
benzene
rings, either fused or connected via alkylene bridges.
Preferred substituents in oil-soluble salicylic acids are alkyl substituents.
In
alkyl - substituted salicylic acids, the alkyl groups advantageously contain 5
to 100,
preferably 9 to 30, especially 14 to 20, carbon atoms. Where there is more
than one alkyl
group, the average number of carbon atoms in all of the alkyl groups is
preferably at least 9
to ensure adequate oil solubility.
CA 3038157 2019-03-27
Lubricating oil compositions of the present invention preferably comprise one
or
more metal detergents that are neutral or overbased alkali or alkaline earth
metal salicylates.
Highly preferred salicylate detergents include alkaline earth metal
salicylates, particularly
magnesium and calcium, especially, calcium salicylates. The metal salicylate
may be the
sole metal-containing detergent present in the lubricating oil composition of
all aspects of
the present invention. Alternatively, other metal-containing detergents, such
as metal
sulfonates or phenates, may be present in the lubricating composition.
Preferably, the
salicylate detergent provides the majority of the detergent additive in the
lubricating oil
composition.
The total amount of metal-containing detergent additive present in the
lubricating oil
composition according to any aspect of the present invention is suitably in
the range of
0.1-10 mass%, preferably from 0.5 to 5 mass% on an active matter basis.
Anti-wear additives reduce friction and excessive wear and are usually based
on
compounds containing sulfur or phosphorous or both, for example that are
capable of
depositing polysulfide films on the surfaces involved. Noteworthy are
dihydrocarbyl
dithiophosphate metal salts wherein the metal may be an alkali or alkaline
earth metal, or
aluminium, lead, tin, molybdenum, manganese, nickel, copper, or preferably,
zinc.
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,
dithiophosphoric acids
can be prepared where the hydrocarbyl groups are entirely secondary in
character or the
hydrocarbyl groups on 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:
26
CA 3038157 2019-03-27
RO
\ I
P ¨ 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. 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 ZDDP is added to the lubricating oil compositions in amounts sufficient to
provide at least 500 ppm such as at least 600ppm or at least 800ppm 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 no more than 1200 ppm or, preferably no more than 1000ppm, 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.
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,
27
CA 3038157 2019-03-27
styrene/butadiene, and isoprene/butadiene, as well as the partially
hydrogenated homopolymers
of butadiene and isoprene and isoprene/divinylbenzene. Suitable viscosity
modifiers for all
aspects of the present invention are copolymers of an unsaturated dicarboxylic
acid and a vinyl
compound, inter polymers of styrene and acrylic esters, and, most preferably,
partially
hydrogenated copolymers of styrene/ isoprene, styrene/butadiene, and
isoprene/butadiene, as
well as the partially hydrogenated homopolymers of butadiene and isoprene and
isoprene/divinylbenzene. The preferred partially hydrogenated copolymers of
styrene/
isoprene, styrene/butadiene, and isoprene/butadiene, may be random copolymers
but are
preferably block copolymers. The preferred, partially hydrogenated copolymers
of
styrene/isoprene, styrene/butadiene, and isoprene/butadiene, and partially
hydrogenated
homopolymers of butadiene and isoprene and isoprene/divinylbenzene viscosity
modifiers may
be linear polymers or star (radial) polymers.
Linear block copolymers useful in the practice of the present invention may be
represented by the following general formula:
Az-(B-A)y-B.
wherein:
A is a polymeric block comprising predominantly monoalkenyl aromatic
hydrocarbon
monomer units;
B is a polymeric block comprising predominantly conjugated diolefin monomer
units;
x and z are, independently, a number equal to 0 or 1; and
y is a whole number ranging from 1 to about 15.
Useful tapered linear block copolymers may be represented by the following
general
formula:
A-A/B-B
wherein:
A is a polymeric block comprising predominantly monoalkenyl aromatic
hydrocarbon
monomer units;
B is a polymeric block comprising predominantly conjugated diolefin monomer
units; and
A/B is a tapered segment containing both monoalkenyl aromatic hydrocarbon and
conjugated diolefin units.
28
CA 3038157 2019-03-27
Star or radial homopolymers or random copolymers of diene(s) (e.g., isoprene
and/or
butadiene) may be represented, generally, by the following general formula:
(B)n-C
wherein:
.. B and C are as previously defined; and
n is a number from 3 to 30;
C is the core of the radial polymer formed with a polyfunctional coupling
agent;
B' is a polymeric block comprising predominantly conjugated diolefin units,
which B' may
be the same or different from B; and
n' and n" are integers representing the number of each type of arm and the sum
of n' and n"
will be a number from 3 to 30.
Star or radial block copolymers may be represented, generally, by the
following
general formula:
(Bx-(A-B)y-Az),-C; and
wherein:
A, B, x, y and z are as previously defined;
n is a number from 3 to 30;
C is the core of the radial polymer formed with a polyfunctional coupling
agent;
B' is a polymeric block comprising predominantly conjugated diolefin units,
which B' may
be the same or different from B; and
n' and n" are integers representing the number of each type of arm and the sum
of n' and n"
will be a number from 3 to 30.
As used herein in connection with polymer block composition, the term
.. "predominantly" means that the specified monomer or monomer type which is
the principle
component in that polymer block is present in an amount of at least 85% by
weight of the
block.
The lubricating oil composition according to all aspects of the present
invention may
comprise one or more star polymer viscosity modifier one or more linear
polymer viscosity
modifier or a mixture of linear and star polymer viscosity modifiers.
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Oil-soluble viscosity modifying polymers generally have weight average
molecular
weights of from 10,000 to 1,000,000, preferably 20,000 to 500,000, which may
be
determined by gel permeation chromatography or by light scattering.
In an embodiment of the present invention, the viscosity modifier comprises a
polymethacrylate, polyalkylmethacrylate or methacrylate copolymer viscosity
modifier. In a
preferred embodiment, the polymethacrylate, polyalkylmethacrylate or
methacrylate
copolymer viscosity modifier is the only viscosity modifier in the lubricating
oil composition.
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 increase.
Examples of suitable antioxidants are selected from copper-containing
antioxidants,
sulfur-containing antioxidants, aromatic amine-containing antioxidants,
hindered phenolic
antioxidants and dithiophosphates derivative.
Preferred anti-oxidants are ashless
antioxidants. Preferred ashless antioxidants are ashless aromatic amine-
containing
antioxidants, ashless hindered phenolic antioxidants and mixtures thereof
Preferably, one
or more antioxidant is present in a lubricating oil composition of all aspects
of the present
invention. In a preferred embodiment, a lubricating oil composition of the
present invention
comprises a combination of aromatic amine antioxidants and hindered phenolic
antioxidant
and optionally also a sulfurized olefin antioxidant.
Rust inhibitors selected from the group consisting of nonionic polyoxyalkylene
polyols
and esters thereof, polyoxyalkylene phenols, and anionic alkyl sulfonic acids
may be used.
In a preferred embodiment of the present invention, no copper-containing
additives are
present in the lubricating oil composition.
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.
CA 3038157 2019-03-27
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 diallcyl fumarate/vinyl acetate copolymers, polyalkylmethacrylates
and the like.
Foam control can be provided by many compounds including an antifoamant of the
polysiloxane type, for example, silicone oil or polydimethyl siloxane.
Suitable additional additives and their common treat rates are discussed
below. All
the values listed are stated as mass percent active ingredient in a fully
formulated lubricant.
Additive Mass % Mass %
(Broad) (Preferred)
Corrosion Inhibitor 0 ¨ 5 0¨ 1.0
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
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 additives; the remainder being oil of lubricating viscosity.
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.
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
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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.
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.
The lubricating oil composition of the present invention may have a sulphated
ash
content of less than or equal to 1.2, preferably less than or equal to 1.1,
more preferably less
than or equal to 1.0, mass % (ASTM D874) based on the total mass of the
composition. The
lubricating oil composition of the present invention suitably has a sulphated
ash content of
at least 0.4, preferably at least 0.5, such as at least 0.6 mass % (ASTM D874)
based on the
total mass of the composition. Suitably the sulphated ash content of the
lubricating oil
composition is in the range of 0.4-1.2 mass%, preferably in the range of 0.6
to 1.0 mass%
(ASTM D874).
The amount of sulfur in the lubricating oil composition will depend upon the
particular application of the lubricating oil composition. The lubricating oil
composition
may contain sulphur in an amount of up to 0.4, such as, up to 0.35 mass %
sulphur (ASTM
D2622) based on the total mass of the composition. Generally the lubricating
oil
composition will contain at least 0.1, or even at least 0.2 mass% sulphur
(ASTM D2622)
based on the total mass of the composition.
Suitably, the lubricating oil composition of all aspects and embodiments of
the
present invention may have a total base number (TBN), as measured in
accordance with
ASTM D2896, of 4 to 15, preferably 4 to 10 mg KOH/g.
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EXAMPLES
The invention will now be described in the following examples which are not
intended to limit the scope of the claims hereof.
Example 1
The Schwingung Reibung Verschleiss "SRV", supplied by OptimolTm, is used to
evaluate friction and wear properties of liquid lubricants across a broad
range of applications.
The test oil forms a film in between a ball and disk, the ball is engaged in a
sliding or
reciprocating stroke across the disk and friction between the metal-metal
contact is
measured. This is used to evaluate the boundary regime friction
characteristics of the oils.
There are different specimens and configurations that can be used in SRV. In
these examples
the average friction was recorded at a frequency of 20 Hz and a temperature of
80 C .
Two oils having the formulations set out in Table 1 below were tested and the
average
friction coefficient was recorded at each of the loads shown in Table 2 below.
Table 1
Additive Oil 1 Oil 2 Oil 3 Oil 4
Additive Package' 10.29 10.29
Additive Package8 9.95 9.95
Dim eric Molybdenum 0.70 0.70 0.80 0.80
Dithiocarbamate2
Trimeric Molybdenum 0.20 0.20
Dithiocarbamate3
Sulfurised ester antioxidant' 0.90
Irgam eirm395 0.01 0.01
Viscosity modifier 6.90 6.90 6.60 6.60
Group ifi base oil Balance Balance Balance Balance
Mo, ppm (ASTM D5185) 865 865 800 800
33
Date Recue/Date Received 2022-11-18
'The additive package had the same composition for Oils 1 and 2 and comprised
a dispersant combination comprising non-borated and
borated polyisobutenyl succinimide dispersant, a calcium salicylate detergent,
a magnesium salicylate detergent, a combination of hindered
phenol and diphenylamine antioxidants and zinc dialkyldithiophosphate.
Dimeric molybdenum dithiocarbamate, Sakuralube 525.
3Trimeric molybdenum dithiocarbamate from Infineum UK Ltd.
Available from Inftneum UK Ltd
1H-benzotriazole- 1 -methanamine, N, N-bis(2-ethylhexyl)-ar-methyl, available
from BASF
The additive package had the same composition for Oils 3 and 4 and comprised a
dispersant combination comprising non-borated and
borated polyisobutenyl succinimide dispersant, a calcium salicylate detergent,
a magnesium salicylate detergent, a combination of hindered
phenol and diphenylamine antioxidants, antifoam and zinc
dialkyldithiophosphate.
Table 2
Average Friction Coefficient Oil 1 Oil 2 Oil 3 Oil 4
20N 0.154 0.125 0.133 0.119
30N 0.124 0.105 0.115 0.107
40N 0.107 0.096 0.103 0.099
50N 0.095 0.089 0.096 0.093
It can be seen from this data that Oils 2 and 4 containing a combination of
molybdenum compound with IrgametTM 39 exhibits significantly lower coefficient
of
friction than the corresponding oil without the hgametTM 39.
Example 2
Four more oils having the formulations set out in Table 3 below were tested
and the
average friction coefficient was recorded at each of the loads shown in Table
4 below.
Table 3
Additive Oil 5 Oil 6 Oil 7 Oil 8
Additive Package 9.95 9.95 9.95 9.95
Dimeric Molybdenum 0.80 0.80 0.80 0.80
Dithiocarbamate
IrgametTm395 0.01 0.01 0.01 0.01
Viscosity Modifier 6.60 6.60 6.60 6.60
34
Date Regue/Date Received 2022-11-18
Ethoxylated amine friction modifier7 0 0.10 0.20 0.30
Group III base oil Balance Balance Balance Balance
Mo, ppm (ASTM D5185) 800 800 800 800
6 The additive package had the same composition for all oils in Table 3 and
comprised a dispersant combination comprising non-borated
and borated polyisobutenyl succinimide dispersant, a calcium salicylate
detergent, a magnesium salicylate detergent, a combination of
hindered phenol and diphenylamine antioxidants and zinc
dialkyldithiophosphate.
2 Dimeric molybdenum dithiocarbamate, Sakuralube 525.
1H-benzotriazole-1-methanamine, N, N-bis(2-ethylhexyl)-ar-methyl, available
from BASF
'Available from lnfineum UK Ltd.
Table 4
Average Friction Coefficient Oil 5 Oil 6 Oil 7 Oil 8
20N 0.142 0.126 0.127 0.126
30N 0.120 0.109 0.108 0.105
-40N 0.107 0.099 0.096 0.094
50N 0.099 0.092 0.088 " 0.089
The data in Table 4 illustrates that addition of an ethoxylated amine friction
modifier to a lubricant containing a combination of molybdenum dithiocarbamate
and a
benzotriazole derivative further reduced the coefficient of friction.
CA 3038157 2019-03-27
