Note: Descriptions are shown in the official language in which they were submitted.
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LUBRICATING OIL COMPOSITION COMPRISING
NON-HYDROGENATED POLYMER
FIELD OF THE INVENTION
This invention relates to a method of improving the seal-compatibility
performance of
lubricating oil compositions used in engine crankcases and transmissions,
particularly lubricating
oil compositions having significant sulphur and/or salicylate soap contents,
and to lubricating oil
compositions having significant sulphur and/or salicylate soap contents that
exhibit enhanced
seals compatibility performance in engines and transmissions containing
nitrile rubber seal
materials. The invention further relates to a method of improving copper
corrosion performance
of lubricating oil compositions used in engine crankcases and transmissions,
particularly
lubricating oil compositions having significant sulphur contents, and to
lubricating oil
compositions having significant sulphur contents that exhibit enhanced seals
and copper corrosion
performance.
BACKGROUND OF TH14: INVENTION
Lubricating oil compositions used to lubricate internal combustion engines and
transmissions contain a major amount of a base oil of lubricating viscosity,
or a mixture of such
oils, and additives used to improve the performance characteristics of the
oil. For example,
additives are used to improve detergency, to reduce engine wear, to provide
stability against heat
and oxidation, to reduce oil consumption, to inhibit corrosion, to act as a
dispersant, and to reduce
friction loss. Some additives provide multiple benefits, such as dispersant-
viscosity modifiers.
Many base oils contain sulfur, and a number of extremely effective additives
conventionally used
in engine and transmission lubricating oil compositions, including zinc
dialkyl dithiophosphates
(.41)DP), certain molybdenum-sulfur compounds, ashless dithiocarbamates and
sulfonate and
some phenate detergents, also contain sulfur and contribute to the overall
sulfur content of such
formulated lubricants.
Modem internal combustion engines and transmissions include numerous gaskets
and
other seals formed of nitrile rubber materials. Lubricant sulfur has been
found to contribute to the
deterioration of materials. Before certifying a crankcase lubricant for use in
their engines, engine
manufacturers (oftentimes referred to as "original equipment manufacturers or
"OEMs") require
passage of a number of performance tests, including tests for compatibility
with engine seal
materials. It is also suspected that high levels of salicylate soap from
salicylate detergents may
contribute to the deterioration of nitrile rubber seal materials, particularly
in "low ash" lubricants.
Therefore, it would be desirable to provide a method of improving the seal
compatibility of
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lubricating oil compositions, particularly lubricating oil compositions having
significant sulfur
contents and/or high levels of salicylate soap, and lubricating oil
compositions having significant
sulfur contents and/or high levels of salicylate soap, that provide improved
seal-compatibility
performance.
Lubricant sulfur has been found to cause copper corrosion. Prior to granting
certification,
OEMs also require lubricating oil compositions to pass a copper corrosion
test. Therefore, it
would be desirable to provide a method of improving the copper corrosion
performance of
lubricating oil compositions, particularly lubricating oil compositions having
significant sulfur
contents, and lubricating oil compositions having significant sulfur contents
that provide
improved copper corrosion performance.
SUMMARY OF THE INVENTION
It has now been found that the addition of a minor amount of a non-
hydrogenated olefin
(co)polymer, for example a polyisobutene, to a lubricating oil composition
improves the
compatibility between the lubricating oil composition and nitrile rubber
engine and transmission
seals, particularly in lubricating oil compositions containing a significant
amount of sulfur, such
as a sulfur content greater than about 0.10 mass %, such as greater than about
0.15 mass %,
particularly greater than about 0.20 mass % and/or significant amounts of
salicylate soap from
salicylate detergents, such as 9 or more, particularly 18 or more, more
particularly 24 or more
mmols of salicylate soap per kilogram of finished lubricant. It has also been
found that the
addition of a minor amount of a non-hydrogenated olefin (co)polymer, for
example a
polyisobutene, to a lubricating oil composition improves the copper corrosion
performance of
lubricating oil compositions, particularly lubricating oil compositions
containing a significant
amount of sulfur, such as a sulfur content greater than about 0.10 mass %,
such as greater than
about 0.15 mass %, particularly greater than about 0.20 mass %.
Therefore, in a first aspect, the invention is directed to a method of
improving the seal
compatibility performance of lubricating oil compositions for the lubrication
of an internal
combustion engine or engine transmission, which method comprises adding to
such lubricating
oil compositions a minor amount of a non-hydrogenated (unsaturated) olefin
(co)polymer.
In a second aspect, the invention is directed to the method of the first
aspect in which the
lubricating oil composition contains a significant sulfur content, such as a
sulfur content greater
than about 0.10 mass %, particularly greater than about 0.15 mass %, such as
greater than about
0.18 mass %, more particularly greater than about 0.20 mass %, and comprises a
major amount of
oil of lubricating viscosity; a minor amount of at least one sulphur-
containing additive, and from
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about 0.5 mass % to about 10.0 mass % of a non-hydrogenated olefin
(co)polymer, wherein all
mass percentages are based on the total mass of the lubricating oil
composition.
In a third aspect, the invention is directed to the method of the first aspect
in which the
lubricating oil composition comprises a major amount of oil of lubricating
viscosity; a minor
amount of at least one salicylate detergent in an amount introducing into the
lubricating oil
composition 9 or more, particularly 18 or more, more particularly 24 or more
mmols of salicylate
soap per kilogram of lubricating oil composition, and from about 0.5 mass % to
about 10.0 mass
% of a non-hydrogenated olefin (co)polymer, wherein all mass percentages are
based on the total
mass of the lubricating oil composition.
In a fourth aspect, the invention is directed to a lubricating oil composition
containing a
significant sulfur content, such as a sulfur content greater than about 0.10
mass %, particularly
greater than about 0.15 mass %, such as greater than about 0.18 mass %, more
particularly greater
than about 0.20 mass %, comprising a major amount of oil of lubricating
viscosity; a minor
amount of at least one sulphur-containing additive, and from about 0.5 mass %
to about 10.0 mass
% of a non-hydrogenated olefin (co)polymer, wherein all mass percentages are
based on the total
mass of the lubricating oil composition.
In a fifth aspect, the invention is directed to a lubricating oil composition
comprising a
major amount of oil of lubricating viscosity; a minor amount of at least one
salicylate detergent in
an amount introducing into the lubricating oil composition 9 or more,
particularly 18 or more,
more particularly 24 or more mmols of salicylate soap per kilogram of
lubricating oil composition
(finished lubricant), and from about 0.5 mass % to about 10.0 mass % of a non-
hydrogenated
olefin (co)polymer, wherein all mass percentages are based on the total mass
of the lubricating oil
composition.
In a sixth aspect, the invention is directed to a method of the second aspect
or a
lubricating oil composition of the fourth aspect, wherein the sulphur-
containing additives are one
or more of a metal salt of a dihydrocarbyl dithiophosphate (e.g., ZDDP), a
sulfonate detergent, a
sulfurized phenate detergent a molybdenum-sulphur compound and an ashless
dithiocarbamate.
In a seventh aspect, the invention is directed to a method of the second
aspect or a
lubricating oil composition of the fourth aspect, wherein the lubricating oil
composition further
contains a salicylate detergent in an amount introducing into the lubricating
oil composition at
least about 9 mmols of salicylate soap per kilogram of finished lubricant and,
preferably, has a
sulfated ash content of not greater than about 1.1 mass %, more preferably no
greater than 1.05
mass %.
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In an eighth aspect, the invention is directed to a method of the third aspect
or a
lubricating oil composition of the fifth aspect, wherein the lubricating oil
composition contains a
significant sulfur content, such as a sulfur content greater than about 0.10
mass %, particularly
greater than about 0.15 mass %, such as greater than about 0.18 mass %, more
particularly greater
than about 0.20 mass %.
In a ninth aspect, the invention is directed to a method of improving the
copper corrosion
performance of lubricating oil compositions for the lubrication of an internal
combustion engine
or engine transmission, which method comprises adding to such lubricating oil
compositions a
minor amount of a non-hydrogenated (unsaturated) olefin (co)polymer.
In a tenth aspect, the invention is directed to the method of the ninth aspect
in which the
lubricating oil composition contains a significant sulfur content, such as a
sulfur content greater
than about 0.10 mass %, particularly greater than about 0.15 mass %, such as
greater than about
0.18 mass %, more particularly greater than about 0.20 mass %, and comprises a
major amount of
oil of lubricating viscosity; a minor amount of at least one sulphur-
containing additive, and from
about 0.5 mass % to about 10.0 mass % of a non-hydrogenated olefin
(co)polymer, wherein all
mass percentages are based on the total mass of the lubricating oil
composition.
In an eleventh aspect, the invention is directed to the method of the tenth
aspect wherein
the sulphur-containing additives are one or more of a metal salt of a
dihydrocarbyl
dithiophosphate (e.g., 7.1)1)13), a sulfonate detergent, a sulfurized phenate
detergent a
molybdenum-sulphur compound and an ashless dithiocarbamate.
In a twelfth aspect, the invention is directed to a concentrate for preparing
a lubricating
oil composition of the fourth aspect comprising an oleaginous carrier, a non-
hydrogenated olefin
(co)polymer, and one or more sulfur-containing additives.
In a thirteenth aspect, the invention is directed to a concentrate for
preparing a lubricating
oil composition of the fifth aspect comprising an oleaginous carrier, a non-
hydrogenated olefin
(co)polymer, and one or more salicylate detergents.
Other and further objects, advantages and features of the present invention
will be
understood by reference to the following specification.
DETAILED DESCRIPTION OF THE INVENTION
The lubricating oil compositions of the present invention are for lubricating
the crankcase
of an internal combustion engine, preferably a compression-ignited (diesel)
engine, more
preferably a compression-ignited heavy duty diesel engine. Crankcase
lubricating oil
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compositions for a diesel application, in particular for heavy duty diesel
engines, have to be
specifically formulated to meet the performance requirements for such an
application.
Oils of lubricating viscosity useful in the context of the present invention
may be selected
from natural lubricating oils, synthetic lubricating oils and mixtures
thereof. The lubricating oil
may range in viscosity from light distillate mineral oils to heavy lubricating
oils such as gasoline
engine oils, mineral lubricating oils and heavy duty diesel oils. Generally,
the viscosity of the oil
ranges from about 2 centistokes to about 40 centistokes, especially from about
4 centistokes to
about 20 centistokes, as measured at 100 C.
Natural oils include animal oils and vegetable oils (e.g., castor oil, lard
oil); liquid
petroleum oils and hydrorefined, solvent-treated or acid-treated mineral oils
of the paraffinic,
naphthenic and mixed paraffinic-naphthenic types. Oils of lubricating
viscosity derived from coal
or shale also serve as useful base oils.
Synthetic lubricating oils include hydrocarbon oils and halo-substituted
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); polyphenyls (e.g., biphenyls, terphenyls,
allcylated polyphenols); and
allcylated diphenyl ethers and alkylated diphenyl sulfides and derivative,
analogs and homologs
thereof. Also useful are synthetic oils derived from a gas to liquid process
from Fischer-Tropsch
synthesized hydrocarbons, which are commonly referred to as gas to liquid, or
"GTL" base oils.
Alkylene oxide polymers and interpolymers and derivatives thereof where the
terminal
hydroxyl groups have been modified by esterification, etherification, etc.,
constitute another class
of known synthetic lubricating oils. These are exemplified by polyoxyalkylene
polymers
prepared by polymerization of ethylene oxide or propylene oxide, and the alkyl
and aryl ethers of
polyoxyalkylene polymers (e.g., methyl-polyiso-propylene glycol ether having a
molecular
weight of 1000 or diphenyl ether of poly-ethylene glycol having a molecular
weight of 1000 to
1500); and mono- and polycarboxylic esters thereof, for example, the acetic
acid esters, mixed
C3-C8 fatty acid esters and C13 oxo acid diester of tetraethylene glycol.
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 such esters includes
dibutyl adipate, di(2-
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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 esters such as neopentyl glycol,
trimethylolpropane, pentaerythritol,
dipentaerythritol and tripentaerythritol.
Silicon-based oils such as the polyalkyl-, polyaryl-, polyalkoxy- or
polyaryloxysilicone
oils and silicate oils comprise another useful class of synthetic lubricants;
such oils include
tetraethyl silicate, tetraisopropyl silicate, tetra-(2-ethylhexyl)silicate,
tetra-(4-methy1-2-
ethylhexypsilicate, tetra-(p-tert-butyl-phenyl) silicate, hexa-(4-methyl-2-
ethylhexyl)disiloxane,
poly(methyl)siloxanes and poly(methylphenyl)siloxanes. Other synthetic
lubricating oils include
liquid esters of phosphorous-containing acids (e.g., tricresyl phosphate,
trioctyl phosphate, diethyl
ester of decylphosphonic acid) and polymeric tetrahydrofurans.
Other examples of base oil are gas-to-liquid ("GTL") base oils, i.e. the base
oil may be oil
derived from Fischer-Tropsch-synthesized hydrocarbons made from synthesis gas
containing
hydrogen and carbon monoxide using a Fischer-Tropsch catalyst. These
hydrocarbons typically
require further processing in order to be useful as base oil. For example,
they may, by methods
known in the art, be hydroisomerized; hydrocracked and hydroisomerized;
dewaxed; or
hydroisomerized and dewaxed.
The oil of lubricating viscosity may comprise a Group I, Group II or Group
III, base stock
or base oil blends of the aforementioned base stocks. Preferably, the oil of
lubricating viscosity is
a Group II or Group III base stock, or a mixture thereof, or a mixture of a
Group I base stock and
one or more a Group II and Group III. Preferably, a major amount of the oil of
lubricating
viscosity is a Group II, Group III, Group IV or Group V base stock, or a
mixture thereof. In one
particular embodiment, it is preferred that greater than 50 mass %, such as
greater than 60 mass %
of the oil of lubricating viscosity is mineral oil. The base stock, or base
stock blend preferably
has a saturate content of at least 65%, more preferably at least 75%, such as
at least 85%. Most
preferably, the base stock, or base stock blend, has a saturate content of
greater than 90%.
Preferably, the oil or oil blend will have a sulfur content of no greater than
0.5 mass % (e.g., from
about 0.001 to about 0.5 mass %), such as no greater than 0.1 mass % (e.g.,
from about 0.001 to
about 0.1 mass %), preferably from about 0.005 to about 0.05 mass %.
Preferably the volatility of the oil or oil blend, as measured by the Noack
volatility test
(ASTM D5880), is less than or equal to 30 mass %, preferably less than or
equal to 25 mass %,
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more preferably less than or equal to 20 mass %, most preferably less than or
equal to 16 mass %.
Preferably, the viscosity index (VI) of the oil or oil blend is at least 85,
preferably at least 100,
most preferably from about 105 to 140.
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 Depai __ tment, 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 sulfur and have a viscosity index greater than or equal to 80 and
less
than 120 using the test methods specified in Table I.
b) Group II base stocks contain greater than or equal to 90 percent
saturates and less
than or equal to 0.03 percent sulfur and have a viscosity index greater than
or
equal to 80 and less than 120 using the test methods specified in Table I.
c) Group III base stocks contain greater than or equal to 90 percent
saturates and
less than or equal to 0.03 percent sulfur and have a viscosity index greater
than or
equal to 120 using the test methods specified in Table I.
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 I - Analytical Methods for Base Stock
Property Test Method
Saturates ASTM D 2007
Viscosity Index ASTM D 2270
Sulfur ASTM D 2622
ASTM D 4294
ASTM D 4927
ASTM D 3120
The non-hydrogenated olefin (co)polymer useful in the practice of the present
invention
is preferably a polymer or copolymer of one or more acyclic olefin monomers.
Generally, the
non-hydrogenated olefin (co)polymers useful in the invention have, or have on
average, about one
double bond per polymer chain.
The (co)polymer may be prepared by polymerizing alpha-olefin monomer, or
mixtures of
alpha-olefin monomers, or mixtures comprising ethylene and at least one C3 to
C28 alpha-olefin
monomer, in the presence of a catalyst system comprising at least one
metallocene (e.g., a
cyclopentadienyl-transition metal compound) and an alumoxane compound. Using
this process, a
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polymer in which 95 % or more of the polymer chains possess terminal
ethenylidene-type
unsaturation can be provided. The percentage of polymer chains exhibiting
terminal ethenylidene
unsaturation may be determined by FUR spectroscopic analysis, titration, or
C13 NMR.
Interpolymers of this latter type may be characterized by the formula POLY-
C(R1)=CH2 wherein
R1 is C1 to C26 alkyl, preferably C1 to C18 alkyl, more preferably C1 to C8
alkyl, and most
preferably C1 to C2 alkyl, (e.g., methyl or ethyl) and wherein POLY represents
the polymer chain.
The chain length of the R1 alkyl group will vary depending on the comonomer(s)
selected for use
in the polymerization. A minor amount of the polymer chains can contain
terminal ethenyl, i.e.
vinyl, unsaturation, i.e. POLY-CH=CH2, and a portion of the polymers can
contain internal
monounsaturation, e.g., POLY-CH=CH(R1), wherein R1 is as defined above. These
terminally
unsaturated interpolymers may be prepared by known metallocene chemistry and
may also be
prepared as described in U.S. Patent Nos. 5,498,809; 5,663,130; 5,705,577;
5,814,715; 6,022,929
and 6,030,930.
Another useful class of (co)polymers is (co)polymers prepared by cationic
polymerization
of isobutene, styrene, and the like. Common (co)polymers from this class
include polyisobutenes
obtained by polymerization of a C4 refinery stream having a butene content of
about 35 to about
75% by wt., and an isobutene content of about 30 to about 60% by wt., in the
presence of a Lewis
acid catalyst, such as aluminum trichloride or boron trifluoride, with
aluminium trichloride
preferred. 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. Polyisobutylene is a most preferred polymer of the present
invention because it is
readily available by cationic polymerization from butene streams (e.g., using
A1C13 or BF3
catalysts). Such polyisobutylenes generally contain residual unsaturation in
amounts of about one
ethylenic double bond per polymer chain, positioned along the chain. 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.
Preferably, these
polymers, referred to as highly reactive polyisobutylene (HR-PIE), have a
terminal vinylidene
content of at least 65%, e.g., 70%, more preferably at least 80%, most
preferably, at least 85%.
The preparation of such polymers is described, for example, in U.S. Patent No.
4,152,499. HR-
NB is known and HR-PEB is commercially available under the tradenames
GlissopalTM (from
BASF) and UltravisTM (from BP-Amoco).
In another embodiment, the non-hydrogenated olefin (co)polymer, for example,
polyisobutylene, has at most 10, such as 5 to 10, %, of the polymer chains
possessing a terminal
double bond (or terminal ethenylidene-type or terminal vinylidene
unsaturation). Such a polymer
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is considered not highly reactive, an example of a commercially available
polymer is under
tradename NapvisTm (from BP-Amoco), and usually obtained by polymerization
with aluminium
trichloride as catalyst.
Preferably the (co)polymer is derived from polymerisation of one or more
olefins having
2 to 10, such as 3 to 8, carbon atoms. An especially preferred olefin is
butene, advantageously
isobutene.
The number average molecular weight of the non-hydrogenated olefin (co)polymer
useful
in the present invention is preferably in the range of from about 450 to about
2300, such as from
about 450 to about 1300, preferably from about 450 to about 950. The molecular
weight can be
determined by several known techniques. A convenient method for such
determination is by 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). Further, it is
preferred that the
kinemantic viscosity of the non-hydrogenated olefin polymer at 100 C, as
measured according to
ASTM D445, is at least 9 or 15, such as 100 or 150 to 3000, advantageously 200
to 2500 or 2700
mm2s1. In one embodiment of the present invention, a polyisobutylene polymer
having a number
average molecular weight of 450 to 2300, and a kinematic viscosity at 100 C of
from about 200
to 2400 mm2s-1 was found to provide particularly beneficial properties.
Lubricating oil
compositions of the present invention can contain the non-hydrogenated olefin
polymer in an
amount of from about 0.2 to about 10.0 mass %, such as from about 0.3 to about
5.0 mass %,
particularly from about 0.5 to about 3.0 mass %, preferably from about 1.0 to
about 2.5 mass %.
Dispersants (or dispersant additives), such as ashless (i.e. metal-free)
dispersants hold
solid and liquid contaminants, resulting from oxidation during use, in
suspension and thus
preventing sludge flocculation and precipitation or deposition on metal parts;
they comprise
long-chain hydrocarbons, to confer oil-solubility, with a polar head capable
of associating with
particles to be dispersed. A noteworthy group is hydrocarbon-substituted
succinimides.
Generally, ashless dispersants form substantially no ash on combustion, in
contrast to
metal-containing (and thus ash-forming) detergents. Borated, metal-free
dispersants are also
regarded herein as ashless dispersants. "Substantially no ash" means that the
dispersant may give
trace amounts of ash on combustion, but amounts which do not have practical or
significant effect
on the performance of the dispersant. A dispersant additive composition
containing two or more
dispersants may also be used.
Ashless, dispersants comprise an oil soluble polymeric long chain backbone
having
functional groups capable of associating with particles to be dispersed.
Typically, such
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dispersants have amine, amine-alcohol or amide polar moieties attached to the
polymer backbone,
often via a bridging group. The ashless dispersant may be, for example,
selected from oil soluble
salts, esters, amino-esters, amides, imides and oxazolines of long chain
hydrocarbon-substituted
mono- and polycarboxylic acids or anhydrides thereof; thiocarboxylate
derivatives of long chain
hydrocarbons; long chain aliphatic hydrocarbons having polyamine moieties
attached directly
thereto; and Mannich condensation products formed by condensing a long chain
substituted
phenol with formaldehyde and polyalkylene polyamine. Suitable dispersants
include, for
example, derivatives of long chain hydrocarbyl-substituted carboxylic acids,
in which the
hydrocarbyl group has a number average molecular weight tends of less than
15,000, such as less
than 5,000; examples of such derivatives being derivatives of high molecular
weight hydrocarbyl-
substituted succinic acid. Such hydrocarbyl-substituted carboxylic acids may
be derivatized with,
for example, a nitrogen-containing compound, advantageously a polyalkylene
polyamine or
amine-alcohol or amide or ester. Particularly preferred dispersants are the
reaction products of
polyalkylene amines with alkenyl succinic anhydrides. Examples of
specifications disclosing
dispersants of the last-mentioned type are U.S. Patent Nos. 3,202,678;
3,154,560; 3,172,892;
3,024,195; 3,024,237; 3,219,666; 3,216,936; and BE-A-662 875.
The dispersant(s) are preferably non-polymeric (e.g., are mono- or bis-
succinimides).
The dispersant(s) of the present invention may optionally be borated. Such
dispersants 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 about 0.1 to
about 20 atomic
proportions of boron for each mole of acylated nitrogen composition.
Combinations of borated
and non-borated dispersants may also be employed.
An ashless succinimide or a derivative thereof, obtainable from a
polyisobutenylsuccinic
anhydride produced from polybutene and maleic anhydride by a thermal reaction
method using
neither chlorine nor a chlorine atom-containing compound, is a preferred
dispersant.
Dispersancy may be provided by polymeric compounds capable of providing
viscosity
index improving properties and dispersancy, such compounds are known as a
dispersant viscosity
index improver additive or a multifunctional viscosity index improver. Such
polymers differ
from conventional viscosity index improvers in that they provide performance
properties, such as
dispersancy and/or antioxidancy, in addition to viscosity index improvement
(see below under
viscosity modifiers for further detail on multifunctional viscosity
modifiers). In the event, a
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dispersant viscosity index improver additive is used in the lubricating oil
compositions of the
present invention, a dispersant additive is, preferably, also present.
Typically, one or more dispersants and/or dispersant viscosity index
improvers, are used
in heavy duty diesel (HDD) engine lubricating oil composition in amounts that
provide the
lubricating oil composition with a nitrogen content of from about 0.08 mass %
to about 0.35 mass
%, such as from about 0.09 mass % to about 0.25 mass %, preferably from about
0.10 mass % to
about 0.20 mass %. In a passenger car diesel engine lubricating oil
composition (PCDO),
dispersant is generally added in amounts that provide the lubricating oil
composition with a
nitrogen content of from about 0.04 mass % to about 0.10 mass %, such as from
about 0.05 mass
% to about 0.09 mass %, preferably from about 0.065 mass % to about 0.085 mass
%. In a
passenger car motor oil for a spark-ignited engine (PCMO), dispersant is
generally added in
amounts that provide the lubricating oil composition with a nitrogen of from
about 0.02 mass %
to about 0.12 mass %, such as from about 0.03 mass % to about 0.08 mass %,
preferably from
about 0.035 mass % to about 0.05 mass %. In manual transmission fluids (MTF),
dispersant is
generally added in amounts that provide the lubricating oil composition with a
nitrogen content of
from about 0.02 mass % to about 0.08 mass %, such as from about 0.025 mass %
to about 0.06
mass %, preferably from about 0.03 mass % to about 0.05 mass %. In an
automatic transmission
fluid (ATF), dispersant is generally added in an amount providing the
lubricating oil composition
with a nitrogen content of from about 0.02 mass % to about 0.14 mass %, such
as from about 0.05
mass % to about 0.11 mass %, preferably from about 0.06 mass % to about 0.08
mass %.
A detergent (or detergent additive) reduces formation of piston deposits, for
example
high-temperature varnish and lacquer deposits, by keeping finely divided
solids in suspension in
engines; it may also have acid-neutralizing properties. A detergent comprises
metal salts of
organic acids, which are referred herein as soaps or surfactants. A detergent
has a polar head, i.e.
the metal salt of the organic acid, with a long hydrophobic tail for oil
solubility. Therefore, the
organic acids typically have one or more functional groups, such as OH or COOH
or SO3H, for
reacting with a metal, and a hydrocarbyl substituent. A detergent may be
overbased, in which
case the detergent contains an excess of metal in relation to the
stoichiometric quantity needed for
the neutralization of the organic acid. This excess is in the form of a
colloidal dispersion,
typically metal carbonate and/or hydroxide, with the metal salts of organic
acids in a micellar
structure.
Examples of organic acids include sulfonic acids, phenols and sulfurized
derivatives
thereof, and carboxylic acids including aromatic carboxylic acids.
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Phenols may be non-sulfurized or sulfurized. Further, the term "phenol" as
used herein
includes phenols containing more than one hydroxyl group (for example, alkyl
catechols) or fused
aromatic rings (for example, alkyl naphthols) and phenols which have been
modified by chemical
reaction, for example, alkylene-bridged phenols and Mannich base-condensed
phenols; and
saligenin-type phenols (produced by the reaction of a phenol and an aldehyde
under basic
conditions). The phenols are frequently used in sulfurized form. Details of
sulfurization
processes are known to those skilled in the art, for example, see U.S. Patent
Nos.4,228,022 and
4,309,293.
As indicated above, the term "phenol" as used herein includes phenols which
have been
modified by chemical reaction with, for example, an aldehyde, and Marmich base-
condensed
phenols. Aldehydes with which phenols may be modified include, for example,
formaldehyde,
propionaldehyde and butyraldehyde. The preferred aldehyde is formaldehyde.
Aldehyde-
modified phenols suitable for use in accordance with the present invention are
described in, for
example, U.S. Patent Nos. 5 259 967 and 6,310,009. Mannich base-condensed
phenols are
prepared by the reaction of a phenol, an aldehyde and an amine. Examples of
suitable Marmich
base-condensed phenols are described in U.S. Patent Nos. 4,708,809 and
4,740,321. In general,
the phenols may include substituents other than those mentioned above.
Examples of such
substituents are methoxy groups and halogen atoms.
Sulfonic acids are typically obtained by sulfonation of hydrocarbyl-
substituted, especially
alkyl-substituted, aromatic hydrocarbons, for example, those obtained from the
fractionation of
petroleum by distillation and/or extraction, or by the alkylation of aromatic
hydrocarbons. The
alkylaryl sulfonic acids usually contain from about 22 to about 100 or more
carbon atoms. The
sulfonic acids may be substituted by more than one alkyl group on the aromatic
moiety, for
example they may be dialkylaryl sulfonic acids. Preferably the sulfonic acid
has a number
average molecular weight of 350 or greater, more preferably 400 or greater,
especially 500 or
greater, such as 600 or greater. Number average molecular weight may be
determined by ASTM
D3712. Another type of sulfonic acid which may be used in accordance with the
invention
comprises alkyl phenol sulfonic acids. Such sulfonic acids can be sulfurized.
Carboxylic acids include mono- and dicarboxylic acids. Preferred
monocarboxylic acids
are those containing 8 to 30, especially 8 to 24, carbon atoms. (Where this
specification indicates
the number of carbon atoms in a carboxylic acid, the carbon atom(s) in the
carboxylic group(s)
is/are included in that number). Examples of monocarboxylic acids are iso-
octanoic acid, stearic
acid, oleic acid, palmitic acid and behenic acid. Iso-octanoic acid may, if
desired, be used in the
form of the mixture of C8 acid isomers sold by Exxon Chemical under the trade
name
CA 02549517 2013-02-08
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TM
"Cekanoic''. Other suitable acids are those with tertiary substitution at the
a-carbon atom and
dicarboxylic acids with 2 or more carbon atoms separating the carboxylic
groups. Further,
dicarboxylic acids with more than 35 carbon atoms, for example, 36 to 100
carbon atoms, are also
suitable. Unsaturated carboxylic acids can be sulfurized.
A preferred type of carboxylic acid is an aromatic carboxylic acid. The
aromatic moiety
of the aromatic carboxylic acid can contain hetero atoms, 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 allcylene bridges.
The carboxylic moiety may be attached directly or indirectly to the aromatic
moiety.
Preferably the carboxylic acid group is attached directly to a carbon atom on
the aromatic moiety,
such as a carbon atom on the benzene ring. The aromatic moiety may also
contain a second
functional group, such as a hydroxyl group or a sulfonate group, which can be
attached directly or
indirectly to a carbon atom on the aromatic moiety. Preferred examples of
aromatic carboxylic
acids are salicylic acids and sulfurized derivatives thereof, such as
hydrocarbyl substituted
salicylic acid and derivatives thereof. Processes for sulfurizing, for example
a hydrocarbyl-
substituted salicylic acid, are known to those skilled in the art.
Salicylic acids are typically prepared by carboxylation, for example, by the
Kolbe-Schmitt process, of phencocides, and in that case, will generally be
obtained, normally in a
diluent, in admixture with tmcarboxylated phenol.
Preferred substituents for 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.
The metal detergent may be neutral or overbased, such terms are known in the
art. A
detergent additive composition may comprise one or more detergent additives,
which can be a
neutral detergent, an overbased detergent or a mixture of both. The Total Base
Number (TBN) of
detergents will conventionally range from 15 to 600.
Detergents generally useful in the formulation of lubricating oil compositions
also
include "hybrid" detergents formed with mixed surfactant systems, e.g.,
phenate/salicylates
(sometimes referred to as "phenalates"), sulfonate/phenates,
sulfonate/salicylates,
sulfonates/phenates/salicylates, as described, for example, in U.S. Patent
Nos. 6,153,565;
6,281,179; 6,429,178; and 6,429,179.
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A detergent additive composition may contain two or more detergents, for
example, an
alkali metal, such as sodium, detergent, and an alkaline earth metal, such as
calcium and/or
magnesium, detergent. The detergent additive composition may also comprise an
ashless
detergent, i.e. a non-metal containing detergent, typically in the form of an
organic salt of an
organic acid. The detergents are preferably metal containing and Group 1 and
Group 2 metals
are preferred as metals in the detergents, more preferably calcium and
magnesium, especially
calcium.
Typically, one or more detergents are used in heavy duty diesel (HDD) engine
lubricating
oil composition in amounts that provide the lubricating oil composition with a
TBN of from about
4.0 to about 11.5, such as from about 6.0 to about 9.5, preferably from about
7.0 to about 8.25. In
a passenger car diesel engine lubricating oil composition (PCDO), detergent is
generally added in
amounts that provide the lubricating oil composition with a TBN of from about
5.0 to about 12.0,
such as from about 6.0 to about 11.0, preferably from about 7.0 to about 10.5.
In a passenger car
motor oil for a spark-ignited engine (PCMO), detergent(s) is generally added
in amounts that
provide the lubricating oil composition with a TBN of from about 2.5 to about
9.9, such as from
about 4.0 to about 8.0, preferably from about 4.5 to about 7.25. In a power
transmission fluid
(PTF), detergent(s) is generally added in amounts that provide the lubricating
oil composition
with a TBN of from about 0.0 to about 10.0, such as from about 0.5 to about
5.0, preferably from
about 1.0 to about 2.5. Where the detergent is a sulfonate detergent, a
sulfurized phenate
detergent, or a hybrid detergent containing a sulfurized phenate and/or
sulfonate component, the
use of a conventional amount of such detergents can introduce into the
lubricating oil composition
as much as 0.04 mass %, even as much as 0.15 mass %, such as from about 0.06
to about 0.12
mass % of sulfur.
In one embodiment, the invention is directed specifically to lubricating oil
compositions
containing salicylate detergent in an amount introducing at least about 9
mmols (e.g, about 12 to
about 50 mmols), such as at least about 18 mmols (e.g. about 18 to about 33
mmols) particularly
at least about 24 mmols of salicylate soap per kilogram of finished lubricant
and from about 1.0
mass % to about 2.5 mass % of the non-hydrogenated polymer described supra.
In another embodiment, the invention is directed specifically to low ash
compositions
having an ash (reported as sulfated ash or SASH) content of less than 1.1 mass
%, such as less
than 1.05 mass%, preferably less than 0.8 mass %; and a sulfur content of from
about 0.10 mass
% to about 0.40 mass %, such as from about 0.15 mass % to about 0.35 mass %,
preferably from
about 0.20 mass % to about 0.30 mass % of sulfur, which compositions contain
salicylate
detergent in an amount introducing at least about 9 mmols, such as at least
about 18 mmols,
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preferably at least about 24 mmols, of salicylate soap per kilogram of
finished lubricant and from
about 1.0 mass % to about 2.5 mass % of the non-hydrogenated polymer described
supra.
Anti-wear agents reduce friction and excessive wear and are usually based on
compounds
containing sulfur or phosphorus or both. Dihydrocarbyl dithiophosphate metal
salts are
frequently used as anti-wear and antioxidant agents. The metal may be an
alkali or alkaline earth
metal, or aluminum, lead, tin, molybdenum, manganese, nickel or copper. The
zinc salts (ZDDP)
are most commonly used in lubricating oil in amounts of 0.1 to 10, preferably
0.2 to 2 mass %,
based upon the total weight of the lubricating oil composition. They may be
prepared in
accordance with known techniques by first forming a dihydrocarbyl
dithiophosphoric acid
(DDPA), usually by reaction of one or more alcohol or a phenol with P2S5 and
then neutralizing
the formed DDPA with a zinc compound. For example, a dithiophosphoric acid may
be made by
reacting mixtures of primary and secondary alcohols having 1 to 18, preferably
2 to 12, carbon
atoms. 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 zinc salt any basic or neutral zinc
compound could be
used but the oxides, hydroxides and carbonates are most generally employed.
Commercial
additives frequently contain an excess of zinc due to use of an excess of the
basic zinc compound
in the neutralization reaction.
ZDDP provides excellent wear protection at a comparatively low cost and also
functions
as an antioxidant. Preferably a zinc dialky dithiophosphate composition
comprising one or more
zinc dialkyl dithiophosphate, which composition especially contains a mixture
of primary and
secondary alkyl groups, wherein the secondary alkyl groups are in a major
molar proportion, such
as at least 60, advantageously at least 75, more especially at least 85, mole
%, based on the
amount of alkyl groups, is useful in the present invention. Preferably a zinc
dithiophosphate
composition has 90 mole % secondary alkyl groups and 10 mole % primary alkyl
groups.
When used in conventional amounts, sulfur-containing antiwear agents can
introduce into
the lubricating oil composition as much as 0.15 mass %, and even as much as
0.30 mass %, such
as from about 0.16 to about 0.25 mass % of sulfur.
Anti-oxidants increase the composition's resistance to oxidation and may work
by
combining with and modifying peroxides to render them harmless by decomposing
peroxides or
by rendering an oxidation catalyst inert. They may be classified as radical
scavengers (e.g.
sterically hindered phenols, secondary aromatic amines, and organo-copper
salts); hydroperoxide
decomposers (e.g. organo-sulfur and organophosphorus additives); and
multifunctionals. Such
anti-oxidants (or oxidation inhibitors) include hindered phenols, aromatic
amine compounds,
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alkaline earth metal and metal-free alkylphenolthioesters having preferably C5
to C12 alkyl side
chains, ashless alkylene bridged phenols, phosphosulfurized and sulfurized
hydrocarbons,
phosphorous esters, metal and metal-free thiocarbamates & derivatives thereof,
oil soluble copper
compound as described in U.S. Patent No. 4,867,890, and molybdenum containing
compounds.
In the practice of the present invention, the use or otherwise of certain anti-
oxidants may confer
certain benefits. For example, in one embodiment it is preferred that an anti-
oxidant composition
comprising a hindered phenol with an ester group is used. In another
embodiment, it is preferred
to employ an anti-oxidant composition comprising a secondary aromatic amine
and said hindered
phenol. Preferably an antioxidant composition comprising an aromatic amine,
such as
diphenylamine and/or a hindered phenol compound, such as 3,5-bis(allcy1)-4-
hydroxyphenyl
carboxylic acid esters, e.g. IRGANOX L135 as sold by Ciba Speciality
Chemicals, is useful.
Friction modifiers include boundary additives that lower friction coefficients
and hence
improve fuel economy. Examples are esters of polyhydrie alcohols such as
glycerol monoesters
of higher fatty acids, for example glycerol mono-oleate; esters of long chain
polycarboxylic acids
with diols, for example the butane diol esters of dimerized unsaturated fatty
acids; oxazoline
compounds; and alkoxylated alkyl-substituted mono-amines, and alkyl ether
amines, for example,
ethoxylated tallow amine and ethoxylated tallow ether amine. Molybdenum-
containing
compounds and ashless dithiocarbamates are also examples of known friction
modifiers.
Conventionally, one or more organic friction modifiers are used in an amount
of 0.1 to 0.5, such
as 0.2 to 0.4, mass %, based on the mass of the oil composition.
The molybdenum-containing compounds, preferably molybdenum-sulfur compounds,
useful in the present invention may be mononuclear or polynuclear. In the
event that the
compound is polynuelear, the compound contains a molybdenum core consisting of
non-metallic
atoms, such as sulfur, oxygen and selenium, preferably consisting essentially
of sulfur.
To enable the molybdenum-sulfur compound to be oil-soluble or oil-dispersible,
one or
more ligands are bonded to a molybdenum atom in the compound. The bonding of
the ligands
includes bonding by electrostatic interaction as in the case of a counter-ion
and forms of bonding
intermediate between covalent and electrostatic bonding. Ligands within the
same compound
may be differently bonded. For example, a ligand may be covalently bonded and
another ligand
may be electrostatically bonded.
Preferably, the or each ligand is monoanionic and examples of such ligands are
dithiophosphates, dithiocarbamates, xanthates, carboxylates, thioxanthates,
phosphates and
hydrocarbyl, preferably alkyl, derivatives thereof. Preferably, the ratio of
the number of
molybdenum atoms, for example, in the core in the event that the molybdenum-
sulfur compound
CA 02549517 2013-02-08
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is a polynuclear compound, to the number of monoanionic ligands, capable of
rendering the
compound oil-soluble or oil-dispersible, is greater than 1 to 1, such as at
least 3 to 2.
The molybdenum-sulfur compound's oil-solubility or oil-dispersibility may be
influenced
by the total number of carbon atoms present among all of the compound's
ligands. The total
number of carbon atoms present among all of the hydrocarbyl groups of the
compound's ligands
typically will be at least 21, e.g., 21 to 800, such as at least 25, at least
30 or at least 35. For
example, the number of carbon atoms in each alkyl group will generally range
between 1 and 100,
preferably 1 and 40, and more preferably between 3 and 20. Examples of
molybdenum-sulfur
compounds include dinuclear molybdenum-sulfur compounds and trinuclear
molybdenum-sulfur
compounds.
An example of a dinuclear molybdenum-sulfur compound is represented by the
formula:
Xi X4
R1 S X2 S R3
________________________ /\ II/ II
C: Mo Mo ,C
\
R2 S X3 S R4
where R1 to R4 independently denote a straight chain, branched chain or
aromatic hydrocarbyl
group having 1 to 24 carbon atoms; and X1 to X4 independently denote an oxygen
atom or a
sulfur atom. The four hydrocarbyl groups, R1 to R4, may be identical or
different from one
another.
In a preferred embodiment, the molybdenum-sulfur compound is an oil-soluble or
oil-
dispersible trinuclear molybdenum-sulfur compound. Examples of trinuclear
molybdenum-sulfur
compounds are disclosed in U.S. Patent Nos. 5,888,945; 5,906,968; 6,010,987;
6,110,878;
6,153,564; 6,232,276; 6,358,894; 6,541,429; 6,569,820; and European patent
application no.
02078011.
Preferably, the trinuclear molybdenum-sulfur compounds are represented by the
formula
Mo3SkEõL,ApQz, wherein k is an integer of at least 1; E represents a non-
metallic atom selected
from oxygen and selenium; x can be 0 or an integer, and preferably k + x is at
least 4, more
preferably in the range of 4 to 10, such as 4 to 7, most preferably 4 or 7; L
represents a ligand that
confers oil-solubility or oil-dispersibility on the molybdenum-sulfur
compound, preferably L is a
monoanionic ligand; n is an integer in the range of 1 to 4; A represents an
anion other than L, if L
is an anionic ligand; p can be 0 or an integer; Q represents a neutral
electron-donating compound;
and z is in the range of 0 to 5 and includes non-stoichiometric values.
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Those skilled in the art will realize that formation of the trinuclear
molybdenum-sulfur
compound will require selection of appropriate ligands (L) and other anions
(A), depending on,
for example, the number of sulfur and E atoms present in the core, i.e. the
total anionic charge
contributed by sulfur atom(s), E atom(s), if present, L and A, if present,
must be ¨12. The
trinuclear molybdenum-sulfur compound may also have a cation other than
molybdenum, for
example, (alkyl)ammonium, amine or sodium, if the anionic charge exceeds -12.
Examples of Q include water, alcohol, amine, ether and phosphine. It is
believed that the
electron-donating compound, Q, is merely present to fill any vacant
coordination sites on the
trinuclear molybdenum-sulfur compound. Examples of A can be of any valence,
for example,
monovalent and divalent and include disulfide, hydroxide, alkoxide, amide and
thiocyanate or
derivative thereof; preferably A represents a disulfide ion. Preferably, L is
monoanionic ligand,
such as dithiophosphates, dithiocarbamates, xanthates, carboxylates,
thioxanthates, phosphates
and hydrocarbyl, preferably alkyl, derivatives thereof. When n is 2 or more,
the ligands can be
the same or different. In an embodiment, independently of the other
embodiments, k is 4 or 7, n
is either 1 or 2, L is a monoanionic ligand, p is an integer to confer
electrical neutrality on the
compound based on the anionic charge on A and each of x and z is 0. In a
further embodiment,
independently of the other embodiments, k is 4 or 7, L is a monoanionic
ligand, n is 4 and each of
p, x and z is 0. Other examples of molybdenum containing compounds include
molybdenum
carboxylates and molybdenum nitrogen complexes, both of which may be
sulfurised.
Where a sulfur-containing molybdenum compound is employed as a friction
modifier
and/or antioxidant, and used in a conventional amount such as an amount
providing from about
20 ppm to about 250 ppm, such as from about 50 ppm to about 125ppm of Mo, such
compounds
can introduce into the lubricating oil composition about 0.004 mass % or more,
or about 0.008
mass % or more, such as from about 0.004 mass % to about 0.090 mass %, e.g.,
from about 0.008
to about 0.025 mass % of sulfur.
Boron may also be present in the lubricating oil compositions of the present
invention.
Boron-containing additives may be prepared by reacting a boron compound with
an oil-soluble or
oil-dispersible additive or compound. Boron compounds include boron oxide,
boron oxide
hydrate, boron trioxide, boron trifluoride, boron tribromide, boron
trichloride, boron acid such as
boronic acid, boric acid, tetraboric acid and metaboric acid, boron hydrides,
boron amides and
various esters of boron acids. Examples of boron-containing additives include
a borated
dispersant; a borated dispersant VI improver; an alkali metal or a mixed
alkali metal or an
alkaline earth metal borate; a borated overbased metal detergent; a borated
epoxide; a borate
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ester; a sulfurized borate ester; and a borate amide. A preferred boron-
containing additive is a
borated dispersant.
Examples of other additives include rust inhibitors, corrosion inhibitors,
pour point
depressants, anti-foaming agents and viscosity modifiers.
Rust inhibitors selected from the group consisting of nonionic polyoxyalkylene
polyols
and esters thereof, polyoxyalkylene phenols, and anionic alkyl sulfonic 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 U.K.
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 mass % (A.I.).
A small amount of a demulsifying component may be used. A preferred
demulsifying
component is described in EP 330,522. 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 % A.I. A treat rate of 0.001 to 0.05
mass % (A.I.) is
convenient.
Pour point depressants, otherwise known as lube oil 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 and C18
dialkyl fumarate/vinyl acetate copolymers, polyallcylmethacrylates 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.
Viscosity index improvers (or viscosity modifiers) impart high and low
temperature
operability to a lubricating oil and permit it to remain shear stable at
elevated temperatures and
also exhibit acceptable viscosity or fluidity at low temperatures. Suitable
compounds for use as
viscosity modifiers are generally high molecular weight hydrocarbon polymers,
e.g.
polyisobutylene, copolymers of ethylene and propylene and higher alpha-
olefins; polyesters, such
as polymethacrylates; hydrogenated poly(styrene-co-butadiene or ¨isoprene)
polymers and
modifications (e.g., star polymers); and esterified poly(styrene-co-maleic
anhydride) polymers.
CA 02549517 2013-06-27
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Oil-soluble viscosity modifying polymers generally have number average
molecular weights
of at least 15,000 to 1,000,000, preferably 20,000 to 600,000, as determined
by gel
permeation chromatography or light scattering methods. The disclosure in
Chapter 5 of
"Chemistry & Technology of Lubricants", edited by R.M. Mortier and S.T.
Orzulik, First
edition, 1992, Blackie Academic & Professional. The VM used may have that sole
function,
or may be multifunctional, such as demonstrating viscosity index improving
properties as
well as dispersant properties. Dispersant olefin copolymers and dispersant
polymethacrylates
are examples of dispersant viscosity index improver additives. Dispersant
viscosity index
improver additives are prepared by chemically attaching various functional
moieties, for
example amines, alcohols and amides, onto polymers, which polymers preferably
tend to have
a number average molecular weight of at least 15,000, such in the range from
20,000 to
600,000, as determined by gel permeation chromatography or light scattering
methods. The
polymers used may be those described below with respect to viscosity
modifiers. Therefore,
amine molecules may be incorporated to impart dispersancy and/or antioxidancy
characteristics, whereas phenolic molecules may be incorporated to improve
antioxidant
properties. A specific example, therefore, is an inter-polymer of ethylene-
propylene post
grafted with an active monomer such as maleic anhydride and then derivatized
with, for
example, an alcohol or amine. In the event a dispersant viscosity modifier is
used in the
present invention, the nitrogen content of the lubricating oil composition
also includes that
derived from the dispersant viscosity modifier. An example of a dispersant
viscosity modifier
is Hitect 5777, which is manufactured and sold by Afton Corp. U.S. Patent Nos.
4,867,890
and 5,958,848 describe examples of dispersant viscosity index improvers.
Generally,
viscosity modifiers, whether multifunctional or not, are used in an amount
depending on the
desired viscometric grade (e.g., SAE 10W-40) of the lubricating oil
composition, for example,
an amount of 0.001 to 2, preferably 0.01 to 1.5, such as 0.1 to 1, mass % of
the polymer,
based on the mass of the oil composition.
Representative effective amounts of such additives, when used in lubricating
oil
compositions, are as follows:
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Additive Mass % a.i.* Mass % a.i.*
(Broad) (Preferred)
Viscosity Modifier 0.01-6 0.01-4
Corrosion Inhibitor 0.0-5 0.01-1.5
Oxidation Inhibitor 0.01-5 0.01-3
Friction Reducer 0.01-5 0.01-1.5
Dispersant 0.1-20 0.1-8
Multifuctional Viscosity Modifier 0.0 -5 0.05-5
Detergent 0.01-6 0.01-4
Anti-wear Agent 0.01-6 0.01-4
Pour Point Depressant 0.01-5 0.01-1.5
Rust Inhibitor 0.0-0.5 0.001-0.2
Anti-Foaming Agent 0.001-0.3 0.001-0.15
Demulsifier 0.0-0.5 0.001-0.2
* mass % active ingredient based on the final lubricating oil composition.
An additive concentrate constitutes a convenient means of handling two or more
additives
before their use, as well as facilitating solution or dispersion of the
additives in lubricant
compositions. When preparing a lubricant composition that contains more than
one type of
additive (sometimes referred to as "additive components"), each additive may
be incorporated
separately. In many instances, however, it is convenient to incorporate the
additives as an
additive concentrate (a so-called additive "package" (also referred to as an
"adpack")) comprising
two or more additives).
In the preparation of the lubricant oil compositions, it is common practice to
introduce
additives in the form of additive concentrate(s) containing the additives.
When a plurality of
additives are employed it may be desirable, although not essential, to prepare
one or more
additive concentrates (also known as additive packages) comprising the
additives, whereby
several additives, with the exception of viscosity modifiers, multifunctional
viscosity modifiers
and pour point depressants, can be added simultaneously to the oil of
lubricating viscosity to form
the lubricating oil composition. Dissolution of the additive concentrate(s)
into the lubricating oil
may be facilitated by diluent or solvents and by mixing accompanied with mild
heating, but this is
not essential. The additive concentrate(s) will typically be formulated to
contain the additive(s) in
proper amounts to provide the desired concentration in the final formulation
when the additive
concentrate(s) is/are combined with a predetermined amount of oil of
lubricating viscosity. If
required, the viscosity modifiers, or multifunctional viscosity modifiers, and
pour point
depressants are then separately added to form a lubricating oil composition.
An additive concentrate may contain 1 to 90, such as 10 to 80, preferably 20
to 80, more
preferably 40 to 70, mass % based on active ingredient, of the additives, the
remainder being an
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oleaginous carrier or diluent fluid (for example, an oil of lubricating
viscosity). The final
lubricating oil composition may typically contain 5 to 40 mass % of the
additive concentrate(s).
The amount of additives in the final lubricating oil composition is generally
dependent on
the type of the oil composition, for example, a heavy duty diesel engine
lubricating oil
composition preferably has 7 to 25, more preferably 8 to 23, such as 8 to 20,
mass % of additives
(including any diluent fluid), based on the mass of the oil composition. A
passenger car engine
lubricating oil composition, for example, a gasoline or a diesel engine oil
composition, tends to
have a lower amount of additives, for example 2 to 16, such as 3 or 4 to 14,
preferably 5 to 12,
especially 6 to 10, mass % of additives, based on the mass of the oil
composition. The amounts
expressed above exclude non-hydrogenated olefin polymer, viscosity modifier
and pour point
depressant additives.
Generally the viscosity of the additive concentrate is higher than that of the
lubricating oil
composition. Typically, the kinematic viscosity at 100 C of the additive
concentrate is at least
50, such as in the range 100 to 200, preferably 120 to 180, mm2s-1 (or cSt).
Thus, a method of preparing a lubricating oil composition according to the
present
invention can involve admixing an oil of lubricating viscosity and one or more
of additives or
additive concentrates that comprises two or more of additives and then,
admixing other additive
components, such as viscosity modifier, and optionally a multifunctional
viscosity modifier and
pour point depressant.
Lubricating oil compositions of the present invention may also be prepared by
admixing
an oil of lubricating viscosity, an additive concentrate containing two or
more additive
components, a non-hydrogenated olefin polymer and a viscosity modifier, and
optionally a
multifunctional viscosity modifier and pour point depressant.
It is preferred that lubricating oil compositions of the invention are
multigrade oil
compositions having a viscometric grade of SAE 10W-X, SAE 5W-X and SAE OW-X,
where X
represents 20, 30 and 40; the characteristics of the different grades can be
found in the SAE J300
classification.
Fully formulated lubricating oil compositions of the present invention
preferably have a sulfur
content of from about 0.15 mass % to about 1.0 mass %, such as from about 0.20
mass % to about
0.35 mass %. Preferably, the Noack volatility of the fully formulated
lubricating oil composition
(oil of lubricating viscosity plus all additives) will be no greater than 13,
such as no greater than
12, preferably no greater than 10. Fully formulated lubricating oil
compositions of the present
invention preferably have a phosphorus content of less than about 1500 ppm,
such as from about
500 to 1500 ppm, preferably less than 1250 ppm, such as from about 500 to
about 1250 ppm,
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more preferably less than about 1200 ppm, such as from about 500 to about 1200
ppm, still more
preferably less than about 850 ppm, such as from about 500 to 850 ppm, based
on the total mass
of the lubricating oil composition.
Fully formulated lubricating oil compositions of the present invention
preferably have a
sulfated ash (SASH) content of about 1.9 mass % or less, preferably about 1.1
mass % or less,
such as about 1.05 mass % or less.
The amount of phosphorus and sulfur are determined according to method ASTM
D5185;
"TBN" is Total Base Number as measured by ASTM D2896; the amount of nitrogen
is
determined according to method ASTM D4629; and sulfated ash is measured
according to
method ASTM D874.
Where the lubricating oil compositions of the present invention are for HDD
use, the
lubricating oil compositions preferably satisfy at least the performance
requirements of the ACEA
E2-96#5, more preferably at least the ACEA E7-04 and/or API CI-4, such as at
least the ACEA
E4-99#3, especially at least the ACEA E6-04 and/or API CJ-4 specification.
Where the
lubricating oil compositions of the present invention are for PCDO use, the
lubricating oil
compositions preferably satisfy at least the performance requirements of the
ACEA B2-98#2,
more preferably at least the ACEA B3-04, such as at least the ACEA B4-04/ ACEA
C3-04,
especially at least the ACEA B5-04/ ACEA C3-04/ ACEA C2-04 specification(s).
Where the
lubricating oil compositions of the present invention are for PCMO use, the
lubricating oil
compositions preferably satisfy at least the performance requirements of the
ACEA A2-96#3/ API
SJ, more preferably at least the ACEA A3-04/ ACEA C3-04, such as at least the
API SL/ LLSAC
GF-3, especially at least the ACEA A5-04/ ACEA C2-04/ ACEA C3-04/ API SM/
rLsAc GF-4
specification(s).
It should be appreciated that interaction may take place between any two or
more of the
additives, including any two or more detergents, after they have been
incorporated into the oil
composition. The interaction may take place in either the process of mixing or
any subsequent
condition to which the composition is exposed, including the use of the
composition in its
working environment. Interactions may also take place when further auxiliary
additives are
added to the compositions of the invention or with components of oil. Such
interaction may
include interaction which alters the chemical constitution of the additives.
Thus, the
compositions of the invention include compositions in which interaction, for
example, between
any of the additives, has occurred, as well as compositions in which no
interaction has occurred,
for example, between the components mixed in the oil.
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The lubricating oil compositions may be used to lubricate mechanical engine
components, particularly an internal combustion, such as a compression-ignited
(diesel) engine,
or a spark-ignited (gasoline) engine or a manual or automatic transmission
unit, by adding the
lubricating oil thereto and operating the engine/transmission.
In this specification the term "hydrocarbyl" as used herein means that the
group
concerned is primarily composed of hydrogen and carbon atoms and is bonded to
the remainder
of the molecule via a carbon atom, but does not exclude the presence of other
atoms or groups in
a proportion insufficient to detract from the substantially hydrocarbon
characteristics of the
group. The term "comprising" or "comprises" when used herein is taken to
specify the presence
of stated features, integers, steps or components, but does not preclude the
presence or addition of
one or more other features, integers, steps, components or groups thereof. In
the instance the term
"comprising" or comprises" is used herein, the term "consisting essentially
of' and its cognates
are a preferred embodiment, while the term "consisting of' and its cognates
are a preferred
embodiment of the term "consisting essentially of'. The term "oil-soluble" or
"oil-dispersible",
as used herein, does not mean that the additives are soluble, dissolvable,
miscible or capable of
being suspended in the oil in all proportions. They do mean, however, that the
additives are, for
instance, soluble or stable dispersible in the oil to an extent sufficient to
exert their intended effect
in the environment in which the oil composition is employed. Moreover, the
additional
incorporation of other additives such as those described above may affect the
solubility or
dispersibility of the additives. "Major amount" means in excess of 50, such as
greater than 70,
preferably 75 to 97, especially 80 to 95 or 90, mass %, of the composition.
"Minor amount"
means less than 50, such as less than 30, for example, 3 to 25, preferably 5
or 10 to 20, mass %,
of the composition mass % of the composition. All percentages reported are
mass % on an active
ingredient basis, i.e. without regard to carrier or diluent oil, unless
otherwise stated. The
abbreviation SAE stands for Society of Automotive Engineers, an organization
that classifies
lubricants by viscosity grades.
EXAMPLES
The invention will now be particularly described, by way of example only, as
follows:
Example 1
A lubricating oil composition representing a conventional 10W40 crankcase
lubricant for
a heavy duty diesel engine meeting the requirements of the ACEA E4-99#3
specification was
prepared by blending a base stock oil of lubricating viscosity, a
detergent/inhibitor (DI) package
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including salicylate detergent, dispersant, ZDDP and antifoamant; a viscosity
modifier (VM) and
lubricating oil flow improver (LOFT). The resulting composition had a nitrogen
content of 0.1
mass %; a sulfur content of 0.3 mass %, a sulfated ash (SASH) content of 1.9
mass %, 1250 ppm
of phosphorus and 43 mmols of salicylate soap per kilogram of finished
lubricant.
Four lubricating oil compositions were prepared based on the above recipe.
Example 1, a
comparative example, contained no added 450 Mi, polybutene (PD3). Examples 2,
3 and 4, which
represent the invention, contained 0.5, 1 and 2 mass % of 450 Mll KB,
respectively. The four
samples were then tested for compatibility with nitrile rubber using the bench
tests used by
Mercedes Benz (MB) or Daimler Chrysler (DC), specifically Test Method
VDA6753014;
Maschinenfabrik Augsburg & Nurnberg (MAN), specifically Test Method DIN 53521
(nitrile
seal); and Motoren und Turbinen Union (MTU); specifically Test Method DIN
53521 (for nitrile
seals). The results are shown below in Table II. Where the tests were repeated
a number of
times, an average result is provided.
Table II
Bench Test Property Limit Ex. 1 (0)
Ex. 2 (0.5) Ex. 3 (1) Ex. 4 (2)
MBSEAL NBR EAB* -35% max -45 -44 -37
TS** -20% max -20 -19 -11
V*** 0 to 10% 0 0 0
H**** -8 to +2 pts. 0 0 0
# of tests --- >5 2 3
0
MANSEAL NBR EAB -30% max -43 --- -36 -
32
TS - -20% max -23 --- -12 -
12
/ 0 to +10% 2 ---
2 2
H -10 pts. max -1
--- -1 -1
# of tests --- >5 0 3
2
MTUSEAL NBR EAB -35% max ' -40 -34 -36
-33
TS -20% max -23 -11 -16 -
17
/ 0 to 10% ' 2
2 2 2
H 0 to -10 pts. -1
-1 -1 -2
_
# of tests --- >5 2 2
2
*elongation at break; **tensile strength; ***volume; ****hardness
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As shown, in each of the bench tests, the addition of PEB resulted in improved
performance, particularly in terms of EAB and TS, sufficiently to provide a
passing result, where
the base formulation failed.
Example 2
A lubricating oil composition representing a low SAPS (sulfated ash,
phosphorus, sulfur)
10W40 crankcase lubricant for a heavy duty diesel engine meeting the
requirements of the ACEA
E6-04 specification was prepared by blending a base stock oil of lubricating
viscosity, a
detergent/inhibitor (DI) package including salicylate detergent, dispersant,
ZDDP and
antifoamant; a viscosity modifier and LOFT (lube oil flow improver). The
resulting composition
had a nitrogen content of 0.16 mass %; a sulfur content of 0.25 mass %, a
sulfated ash (SASH)
content of 0.25 mass % and 800 ppm of phosphorus and 24 mmol of salicylate
soap per kilogram
of finished lubricant.
Four lubricating oil compositions were prepared based on the above recipe.
Example 5, a
comparative example, contained no added 450 Mn polybutene (PLB). Examples 2, 3
and 4, which
represent the invention, contained 2.1, 2.5 and 3.0 mass % of 950 MT, NB,
respectively. The four
samples were then tested for compatibility with nitrile rubber the bench tests
described in
Example 1. The results are shown below in Table III.
Table III
Bench Test Property Limit Ex. 5 (0) Ex. 6 (2.1)
Ex. 7 (2.5) Ex. 8 (3.0)
MBSEAL NBR EAB* -35% max. -57 -31 -33 -27
TS** -20% max. -35 -11 -12 -11
V*** 0 to +10 % 2 2 2 2
H**** -8 to +2 pts. 1 -2 1 -1
MANSEAL NBR EAB -30% max. -55 -28 -27
TS -20% max. -48 -10 -10
V 0 to +10 % 5 5 5
-10 pts. max -2 -3 -4
As shown, the effects of the invention are particularly apparent in low SAPS
HDD
lubricants formulated with salicylate detergents. Again, in each of the bench
tests, the addition of
PM resulted in improved performance, particularly in terms of EAB and TS,
sufficiently to
provide a passing result, where the base formulation failed.
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Example 3
A lubricating oil composition representing a 15W40 crankcase lubricant for a
heavy duty
diesel engine meeting the requirements of the PC-10 specification was prepared
by blending a
base stock oil of lubricating viscosity, a detergent/inhibitor (DI) package
including sulfonate and
sulfurized phenate detergent, dispersant, ZDDP, a molybdenum-sulfur compound,
and
antifoamant; a dispersant/viscosity modifier and LOFT (lube oil flow
improver). The resulting
composition had a sulfur content of 0.31 mass %, a nitrogen content of 0.14, a
SASH content of
0.94; 50 ppm of molybdenum and 1000 ppm of phosphorus.
Four lubricating oil compositions were prepared based on the above recipe.
Example 9, a
comparative example, contained no added 950 Mn polybutene (PM). Examples 10,
11 and 12,
which represent the invention, contained 0.5, 1.0 and 2.0 mass % of 950 Mõ
FIB, respectively.
The four samples were then tested for compatibility with nitrile rubber in the
bench tests
described in Example 1. The results are shown below in Table IV.
Table IV
Bench Test Property Limit Ex. 9 (0) Ex. 10 (0.5)
Ex. 11(1.0) Ex. 12 (2.0)
MBSEAL NBR EAB* -35% max. -37 -29 -23
-21
TS** -20% max. -18 -13 -9
-7
V*** 0 to +10 % 2.1 2 2
2
H**** -8 to +2 pts. -2 -2 -2
-2
As shown, the effects of the invention are also apparent in lubricants
formulated with
phenate and sulfonate detergents. The addition of PLI3 resulted in improved
performance,
specifically in terms of EAB, sufficient to provide a passing result, where
the base formulation
failed.
Example 4
Five lubricating oil compositions were prepared based on the recipe provided
in Example
3. Example 13, a comparative example, contained no added 950 Mn polybutene
(PM). Examples
14, 15, 16 and 17, which represent the invention, contained 2, 3, 4 and 5 mass
% of 950 Mõ FIB,
respectively. The five samples were then tested for corrosion, particularly
copper corrosion,
using the High Temperature Corrosion Bench Test described in ASTM D6594. The
results are
shown below in Table V.
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Table V
Property Limit Ex. 13 Ex. 14 (2) Ex. 15 (3) Ex. 16 (4)
Ex. 12 (5)
Cu 20 max 111 24 13 12 9
Pb 120 max 44 36 37 38 42
Sn 50 max 0 2 2 2 2
Cu Strip 3 4B IA lA IA IA
As demonstrated, the addition of P1B to a lubricating oil composition
containing a
significant sulfur content further improves copper corrosion performance and
allows passage
of the HTCBT with a formulation that fails the test in the absence of the PIB.
The scope of the claims should not be limited by particular embodiments set
forth
herein, but should be construed in a manner consistent with the specification
as a whole.
