Note: Descriptions are shown in the official language in which they were submitted.
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ADDITIVE COMPOSITION FOR TRANSMISSION OIL
The present invention is directed to an additive composition for a
transmission oil.
More particularly, the present=invention is directed to an additive
composition
comprising an oil dispersion of hexagonal boron nitride and a viscosity index
improver, in particular, an additive composition containing a viscosity index
improver
selected from a polymethacrylate, a dispersant polymethacrylate or a
dispersant
olefin copolymer.
REFERENCES
The following references are cited in this application as superscript
numbers:
1 Peeler, U.S. Patent No. 3,313,727, Alkali Metal Borate E.P. Lubricants,
issued April 11, 1967
2 Adams, U.S. Patent No. 3,912,643, Lubricant Containing Neutralized
Alkali Metal Borates, issued October 14, 1975
3 Sims, U.S. Patent No. 3,819,521, Lubricant Containing Dispersed Borate
and a Polyol, issued June 25, 1974
¾ Adams, U.S. Patent No. 3,853,772, Lubricant Containing Alkali Metal
Borate Dispersed with a Mixture of Dispersants, issued December 10, 1974
5 Adams, U.S. Patent No. 3,997,454, Lubricant Corztaining Potassium
Borate, issued December 14, 1976
6 Adams, U.S. Patent No. 4,089,790, Synergistic Conabinations of Hydrated
Potassium Borate, Antiwear Agents, and Organic Sulfide Antioxidants, issued
May
16, 1978
7 Adams, U.S. Patent No. 4,163,729, Synergistic Combinations of Hydrated
Potassium Borate, Antiwear Agents, and Organic Sulfide Antioxidants, issued
August
7, 1979
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CA 02548166 2009-05-04
8 Frost, U.S. Patent No. 4,263,155, Lubricant Composition Containing
an Alkali Metal Borate and Stabilizing Oil-Soluble Acid, issued Apri121, 1981
9 Frost, U.S. Patent No. 4,401,580, Lubricant Composition Containing
an Alkali Metal Borate and an Ester-Polyol Compound, issued August 30, 1983
10 Frost, U.S. Patent No. 4,472,288, Lubricant Composition Containing
an Alkali Metal Borate and an Oil-Soluble Amine Salt of a Phosphorus Compound,
issued September 18, 1984
11 Clark, U.S. Patent No. 4,534,873, Automotive Friction Reducing
Composition, issued August 13, 1985
12 Brewster, U.S. Patent No. 3,489,619, Heat Transfer and Quench Oil,
issued January 13, 1970.
13 Salentine, U.S. Patent No. 4,717,490, Synergistic Combination of
Alkali Metal Borates, Sulfur Compounds, Phosphites and Neutralized Phosphate,
issued January 5, 1988.
BACKGROUND OF THE INVENTION
High load conditions often occur in gear sets such as those used in automobile
transmissions and differentials, pneumatic tools, gas compressors,
centrifuges, high-
pressure hydraulic systems, metal working and similar devices, as well as in
many
types of bearings. When employed in such environments, it is conventional to
add an
extreme-pressure (E.P.) agent to the lubricant composition and, in this
regard, alkali
metal borates are well known extreme-pressure agents for such compositions.
1"1 i''3
E.P. agents are added to lubricants to prevent destructive metal-to-metal
contact in the
lubrication of moving surfaces. While under normal conditions termed
"hydrodynamic", a film of lubricant is maintained between the relatively
moving
surfaces governed by lubricant parameters, and principally viscosity. However,
when
load is increased, clearance between the surfaces is reduced, or when speeds
of
moving surfaces are such that the film of oil cannot be maintained, the
condition of
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"boundary lubrication" is reached; governed largely by the parameters of the
contacting surfaces. At still more severe conditions, significant destructive
contact
manifests itself in various forms such as wear and metal fatigue as measured
by
ridging and pitting. It is the role of E.P. additives to prevent this from
happening. For
the most part, E.P. agents have been oil soluble or easily dispersed as a
stable
dispersion in the oil, and largely have been organic compounds chemically
reacted to
contain sulfur, halogen (principally chlorine), phosphorous, carboxyl, or
carboxylate
salt groups which react with the metal surface under boundary lubrication
conditions.
Stable dispersions of hydrated alkali metal borates have also been found to be
effective as E.P. agents.
Moreover, because hydrated alkali metal borates are insoluble in lubricant oil
media,
it is necessary to incorporate the borate as a dispersion in the oil and
homogenous
dispersions are particularly desirable. The degree of formation of a
1lomogenous
dispersion can be correlated to the turbidity of the oil after addition of the
hydrated
alkali metal borate with higher turbidity correlating to less homogenous
dispersions.
In order to facilitate formation of such a homogenous dispersion, it is
conventional to
include a dispersant in such compositions. Examples of dispersants include
lipophilic
surface-active agents such as alkenyl succinimides or other nitrogen
containing
dispersants as well as alkenyl succinates.1_4' 12 It is also conventional to
employ the
alkali metal borate at particle sizes of less than 1 micron in order to
facilitate the
formation of the homogenous dispersion.11
In addition, anti-sticking agents are often employed in automotive gear boxes
to
provide smooth synchronization and good shift ability. Examples of such anti-
sticking
agents include phosphates, phosphites, phosphonates, thiophosphates,
carbamates,
molybdenum dithiocarbamates and dithiophosphates.
It is also known that boron nitride exhibits friction modifying properties in
lubricants.
For exainple, U.S. Patent No. 4,787,993, issued November 29, 1988 to Nagahiro,
discloses a lubricant effective for the reduction of friction which comprises
dispersing
a finely powdered aromatic or polyamide resin into a fluid fat or oil, which
may
additionally contain molybdenum disulfide, organic molybdenum or boron
nitride.
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Furthermore, U.S. Patent No. 4,715,972, issued December 29, 1987 to Pacholke,
discloses a solid lubricant additive for gear oils comprising solid lubricant
particles
combined with a stabilizing agent and a fluid carrier, wherein the solid
lubricant
particles are selected from the group consisting of molybdenum disulfide,
graphite,
cerium fluoride, zinc oxide, tungsten disulfide, mica, boron nitrate, boron
nitride,
borax, silver sulfate, cadmium iodide, lead iodide, barium fluoride, tin
sulfide,
fluorinated carbon, PTFE, intercalated graphite, zinc phosphide, zinc
phosphate, and
mixtures thereof. This patent further discloses that such lubricant additive
provides
the gear oil with improved demulsibility, stability and compatibility
characteristics of
the gear oil when contaminated with water.
Polymethacrylic acid esters or polymethacrylates are long chain esters
commonly
used in the lubricating oil industry as viscosity index improvers (VII). Their
molecular masses lie predominantly between 20,000 and 500, 000. The properties
of
the homo- or co-polymers of the various alkylmethacrylates differ with the
chain
length of the alcohol used to make the ester and the degree of polymerization.
Olefin
co-polymers (OCP) are manufactured from ethylene and propylene by means of
Ziegler catalysts and are commonly used in the lubricating oil industry as
VIIs.
Dispersant Olefin Co-polymers (DOCP) are multifunctional VIIs ; the viscosity
improving effect is combined with dispersant properties by the inclusion of
cyclic
imides such as N-vinylimidazole and similar fragments in the polymers.
Accordingly, it is an object of an aspect of the present invention to provide
a lubricant
additive composition having good anti-sticking properties when used in
transmission
oils.
SUMMARY OF THE INVENTION
The present invention provides a novel additive composition for a transmission
oil
comprising:
a) an oil dispersion of hexagonal boron nitride and;
b) a viscosity index improver selected from the group consisting of:
i) a polymethacrylate,
ii) a dispersant polymethacrylate, and
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iii) a dispersant olefin copolymer;
wherein the weight ratio of the oil dispersion of hexagonal boron
nitride to the viscosity index improver is in the range of from about
99:1 to about 1:99.
Typically, the concentration of the oil dispersion of hexagonal boron nitride
is from
about 1 to about 99 wt %, preferably from about 5 to about 95 wt % and the
concentration of the viscosity index improver is from about 1 to about 99 wt
%,
preferably from about 5 to about 95 wt %, based on the total weight of the
additive
composition.
The additive composition of the present invention may optionally further
contain an
oil dispersion of hydrated alkali metal borate containing a hydrated alkali
metal
borate, a dispersant, optionally a detergent, and an oil of lubricating
viscosity.
The additive composition of the present invention may be suitably employed in
both
manual transmission gear oils and automatic transmission oils. Preferably, the
additive composition will be employed in a manual transmission gear oil.
The present invention further provides a lubricating oil composition
comprising a
inajor amount of a transmission oil of lubricating viscosity and an effective
synchronizer sticking reducing amount of the additive composition described
above.
Preferably, the transmission oil is a manual transmission gear oil.
Among other factors, the present invention is based in part upon the
surprising
discovery that the unique combination of an oil dispersion of hexagonal boron
nitride
and a certain viscosity index improver selected from a polymethacrylate,
dispersant
polymethacrylate and a dispersant olefin copolymer, provides a significant and
unexpected reduction in synchronizer sticking when used as an additive
composition
in a manual transmission gear oil.
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According to another aspect of the present invention, there is provided an
additive
composition for a transmission oil comprising:
a) an oil dispersion of hexagonal boron nitride; and
b) a viscosity index improver selected from the group consisting of
i) a non-dispersant polymethacrylate, and
ii) a dispersant polymethacrylate,
wherein the weight ratio of the oil dispersion of hexagonal boron nitride to
the
viscosity index improver is in the range of from about 99:1 to about 1:99.
According to still another aspect of the present invention, there is provided
a
lubricating oil composition comprising a major amount of a transmission oil of
lubricating viscosity and an effective synchronizer sticking reducing amount
of an
additive composition comprising:
a) an oil dispersion of hexagonal boron nitride; and
b) a viscosity index improver selected from the group consisting of
i) a non-dispersant polymethacrylate, and
ii) a dispersant polymethacrylate,
wherein the weight ratio of the oil dispersion of hexagonal boron nitride to
the
viscosity index improver is in the range of 99:1 to about 1:99.
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DETAILED DESCRIPTION OF THE INVENTION
As noted above, the present invention is directed to a novel additive
coinposition for a
transmission oil comprising an oil dispersion of hexagonal boron nitride and a
viscosity index improver selected the group consisting of:
a. a polymethacrylate,
b. a dispersant polymethacrylate, and
c. a dispersant olefin copolymer;
wherein the weight ratio of the oil dispersion of hexagonal boron nitride to
the
viscosity index iinprover is in the range of from about 99:1 to about 1:99.
Each of the components in the additive composition of the present invention
will be
described in further detail below. Unless otherwise stated, all percentages
are in
weight percent (wt %).
THE OIL DISPERSION OF HEXAGONAL BORON NITRIDE
The additive composition of the present invention contains an oil dispersion
of
hexagonal boron nitride.
Hexagonal boron nitride, or h-BN, is a hexagonal, graphite-like form of boron
nitride,
having a layered structure and planar 6-membered rings of alternating boron
and
nitrogen atoms. On alternate sheets, boron atoms are directly over nitrogen
atoms.
Hexagonal boron nitride can be prepared by heating boric oxide, boric acid or
boric
acid salts with ammonium chloride, alkali cyanides or calcium cyanamide at
atmospheric pressure. Hexagonal boron nitride may also be prepared by the
reaction
of boron trichloride or boron trifluoride with ammonia. A discussion of
hexagonal
boron nitride can be found, for example, in Kirk-Othmer, Eracyclopedia of
Chernical
Technology, Fourth Edition, Vol. 4, pp. 427-429, Jolin Wiley and Sons, New
York,
1992.
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Generally, the oil dispersion of hexagonal boron nitride will have a mean
particle size
of less than 1 micron. Preferably, the oil dispersion of hexagonal boron
nitride will
have a particle size distribution wherein 90% or greater of the particles are
less than
about 0.5 microns (500 nanometers, nm), with a preferred mean particle size of
less
than about 0.3 microns (300 nrn).
Typically, the oil dispersion of hexagonal boron nitride will contain from
about 1 to
about 50 wt % of the hexagonal boron nitride solids, preferably from about 1
to about
20 wt %, and more preferably from about 5 to about 15 wt %, based on the total
weight of the oil dispersion.
Preferably, the oil dispersion of hexagonal boron nitride will contain a
surfactant as a
stabilizer for the oil dispersion. Typical surfactants for use as a stabilizer
include
ethylene - propylene copolymers, or terpolymers of ethylene, propylene and an
unconjugated dienes commonly known as ethylene-propylene-diene terpolymer,
ethylene-propylene copolymers grafted with a nitrogen-containing vinyl
functionality
selected from the group consisting of N-vinyl pyrrollidone and N-vinyl
pyridine, and
the like. The ethylene-propylene copolymer generally has an average molecular
weight in the range of from about 22,000 to about 200,000. A preferred
surfactant is
ethylene - propylene copolymer which has substantially equal proportions of
ethylene
and propylene monomers and an average molecular weight of from about 22,000 to
about 40,000. When present, the surfactant concentration in the oil dispersion
of
hexagonal boron nitride will typically range from about 0.1 to about 25 wt %,
preferably from about 2 to about 7 wt %, and more preferably from about 3.0 to
about
5.0 wt %, based on the total weight of the oil dispersion of hexagonal boron
nitride.
The lubricant oil used to prepare the oil dispersion of hexagonal boron
nitride may be
selected from the same group of natural or synthetic lubricating oils
described above
for use in preparing the oil dispersion of hydrated alkali metal borate, but
other carrier
fluids have been found to be satisfactory, including vegetable oils such as
rapeseed
oil; liquid hydrocarbons such as aliphatic and aromatic naphthas and mixtures
thereof;
synthetic lubricant fluids such as polyalphaolefins, polyglycols, diester
fluids, and
mixtures of these liquids. Moreover, the oil used in forming the oil
dispersion of
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hexagonal boron nitride may be the same as, or different from, the lubricant
oil
employed in preparing the oil dispersion of hydrated alkali metal borate.
Typical oils
for preparing the oil dispersion of hexagonal boron nitride include the Group
I and
Group II base oils, such as 150 solvent neutral petroleum oil.
In general, the oil dispersion of hexagonal boron nitride is present in the
additive
composition of the present invention in the range of from about 1 to about 99
wt %,
preferably from about 5 to about 95 wt %, and more preferably from about 10 to
about 90 wt %, based on the total amount of the additive composition.
VISCOSITY INDEX IMPROVER (VI IMPROVER)
The additive composition of the present invention contains a polymethacrylate,
dispersant polymethacrylate or a dispersant olefin copolymer VI improver.
A. The Polymethacrylate (PMA) or Dispersant Polymethacrylate
Typically, the polymethacrylate VI improvers employed in the present invention
are
polymeric methacrylates containing short, intermediate, and long-chain
hydrocarbon
side chains. Short-chain hydrocarbon side chains typically have from about 1
to about
7 carbon atoms. For example, both methyl and butyl (either n-butyl, isobutyl,
or
mixtures of the two) methacrylates have been used. Methyl methacrylate is the
most
common. Intermediate-chain hydrocarbon side chains typically contain from
about 8
to about 15 carbon atoms and may be derived from alcohols including 2-
ethylhexyl
alcohol, isodecyl alcohol and alcohol mixtures which may be, for example, C8
to Clo,
Cl Z to C14 or CIZ to Cl 5 alcohol mixtures. Long-chain hydrocarbon side
chains
generally will contain about 16 or more carbon atoms and may be based, for
example,
on C16 to C18 or C16 to C20 alcohol mixtures.
The polymethacrylate VI improvers which may be employed in the present
invention
are any type of non-dispersant type or dispersant type polymethacrylate
compounds
which are used as VI improvers for a lubricating oil.
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The non-dispersant type polymethacrylate VI improvers may be a polymer of a
compound represented by the formula:
CH2 = C(CH3) - CO2 - R'
In formula (1) R' is a straight chain or branched alkyl group such as methyl,
ethyl,
propyl, butyl, hexyl, heptyl, octyl, nonyl, decyl, undecyl, dodecyl, tridecyl,
tetradecyl,
pentadecyl, hexadecyl, heptadecyl, and octadecyl groups.
Dispersancy may be incorporated into the PMA with an appropriate polar monomer
by any number a methods known by the skilled artisan such as copolymerization,
graft polymerization or post reaction of a reactive species into or onto the
polymer.
Typically, such methods involve the incorporation of a polar group derived
from
nitrogen or oxygen. Nitrogen-based groups are derived from amines, for
example,
polyalkyleneamines such as diethylenetriamine and triethylenetetramine. Oxygen-
based groups are alcohol-derived such as hydroxyethyl methacrylates or ether-
containing methacrylates. Although nitrogen-based PMAs are exemplified in the
present invention, oxygen-based PMAs are also contemplated within the scope of
the
present invention. Examples of oxygen-based PMAs are those derived from
polyhydric alcohols such as glycols, trivalent alcohols such as glyercol and
higher
alcohols, such as erythrytol, pentaerythrytol, mannitol and the like.
Moreover, ether-
containing PMAs are also well known in the art. Further details of oxygen-
based
PMAs may be found, for example, in US Patents Nos. 3,249,545 and 3,052,648.
Specific examples of the dispersant polymethacrylate VI improvers are
copolymers
obtained by copolymerizing one or more monomers selected from compounds
represented by formula (1) with one or more nitrogen-containing monomers
selected
from compounds represented by formulas (2) and (3)
CH2 = C(R2) CO2 - R3-Xl
Formula 2
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CH2 = C(R4) - X2
Formula 3
In formulas (2) and (3) R2 and R~ are each independently hydrogen or methyl,
R3 is a
straight chain or branched alkylene group having from about 1 to about 18
carbon
atoms, such as ethylene, propylene, butylene, pentylene, hexylene, heptylene,
octylene, nonylene, decylene, undecylene, dodecylene, tridecylene,
tetradecylene,
pentadecylene, hexadecylene, heptadecylene, and octadecylene groups, Xl and X2
are
each independently an amino- or heterocyclic- residue having about 1 or about
2
nitrogen atoms and 0 to about 2 oxygen atoms. Specific examples of Xl and X2
are
dimethylamino, diethylamino, dipropylamino, dibutylamino, anilino, toluidino,
xylidino, acetylamino, benzoilamino, morpholino, pyrolyl, pyridyl,
methylpyridyl,
pyrolidinyl, piperidinyl, quinonyl, pyrrolidonyl, pyrrolidono, imidazolino,
and
pyrazino groups.
Specific examples of the nitrogen-containing monomers represented by formula
(2) or
(3) are dimethylaminomethylmethacrylate, diethylaminomethylmethacrylate,
dimethylaminoethylmethacrylate, diethylaminoethylmethacrylate, 2-methyl-5-
vinylpyridine, morpholinomethylmethacrylate, morpholinoethylmethacrylate, N-
vinylpyrrolidone, and mixtures thereof.
A particularly beneficial PMA employed in the present invention is an ester
polymer,
having principally from about 1 to about 20, preferably from about 8 to about
14,
carbon atoms. It can be prepared by a polymerization reaction with a basic
monomer
and a peroxide or azoic initiator in a hydrocarbon solvent such as toluene or
a mineral
or synthetic base oil. The basic monomers used to prepare the PMA are
principally
monocarboxylic acid esters such as methacrylate, acrylate, crotonate,
tiglicate, and
angelicate. The PMA may also be prepared by reaction with olefinic copolymers
(i.e.,
ethylene-propylene copolymer) in oil.
The average molecular weiglzt of the PMA will be in the range of from about
20,000
to about 500,000. Preferably, the molecular weight will range from about
50,000 to
about 300,000 and more preferably, from about 80,000 to about 150,000.
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A further discussion of PMA VI improvers and dispersant PMA VI improvers can
be
found, for example, in "Lubricant Additives Chefnistry and Applications ",
Leslie R.
Rudnick, Editor, Chapters 5 and 11, Marcel Dekker, Inc, New York 2003 and U.S.
Patent No. 6,642,189.
B. Dispersant Olefin Copolymer (OCP)
The dispersant OCPs employable in the present invention include copolymers of
two
or more olefins such as ethylene, propylene, butylene, iso-butylene, isoprene,
butadiene and the like, as well as copolymers of these olefms with other
monomers
such as styrene, cyclopentadiene, dicyclopentadiene, ethylidene-norbomene and
so
on.
Exemplary dispersant OCPs for the purpose of the present invention relate to
ethylene
copolymers. Oil soluble ethylene copolymers used in the invention generally
will
have a number-average molecular weight (Mõ) of from above about 5,000 to about
500,000; preferably from about 10,000 to about 200,000 and optimally from
about
20,000 to about 100,000. They will generally have a narrow range of molecular
weight, as determined by the ratio of weight-average molecular weight (Mw) to
number average molecular weight (Mõ). Polymers having a MW /Mõ of less than
10,
preferably less than 7, and more preferably 4 or less are most desirable. As
used
herein and (Mõ) and (M,) are measured by the well known techniques of vapor
phase
osmometry (VPO), membrane osmometry and gel permeation chromatography. In
general, polymers having a narrow range of molecular weight may be obtained by
a
choice of synthesis conditions such as choice of principal catalyst and
cocatalyst
combination, addition of hydrogen during the synthesis, etc. Post synthesis
treatment
such as extrusion at elevated temperature and under high shear through small
orifices,
mastication under elevated temperatures, thermal degradation, fractional
precipitation
from solution, etc. may also be used to obtain narrow ranges of desired
molecular
weights and to brealc down higher molecular weigllt polymer to different
molecular
weight grades for VI use.
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These polymers are prepared from ethylene and ethylenically unsaturated
hydrocarbons including cyclic, alicyclic and acyclic, containing from about 3
to about
28 carbons, e.g. about 2 to about 18 carbons. These ethylene copolymers may
contain
from about 15 to about 90 wt. % ethylene, preferably from about 30 to about 80
wt. %
of ethylene and from about 10 to about 85 wt. %, preferably from about 20 to
about
70 wt. % of one or more C3 to C28, preferably C3 to C18, more preferably C3 to
C8,
alpha olefins. While not essential, such copolymers preferably have a degree
of
crystallinity of less than 25 wt. %, as determined by X-ray and differential
scanning
calorimetry. Copolymers of ethylene and propylene are most preferred. Other
alpha-
olefins suitable in place of propylene to form the copolymer, or to be used in
combination with ethylene and propylene to form a terpolymer, tetrapolymer,
etc.,
include 1-butene, 1-pentene, 1-hexene, 1-heptene, 1-octene, 1-nonene, 1-
decene, etc.;
also branched chain alpha-olefins, such as 4-methyl-l-pentene, 4-methyl-l-
hexene,
4,4-dimethyl-l-pentene, and 6-methylheptene-1, etc., and mixtures thereof.
The term copolymer as used herein, unless otherwise indicated, includes
terpolymers,
tetrapolymers, etc., of ethylene, said C3 to C28 alpha-olefin and/or a non-
conjugated
diolefin or mixtures of such diolefins which may also be used. The amount of
the non-
conjugated diolefin will generally range from about 0.5 to about 20 mole
percent,
preferably from about 1 to about 7 mole percent, based on the total amount of
ethylene and alpha-olefin present.
Representative examples of non-conjugated dienes that may be used as the third
monomer in the terpolymer include:
a. Straight chain acyclic dienes such as: 1,4-hexadiene; 1,5-heptadiene; 1,6-
octadiene.
b. Branched chain acyclic dienes such as: 5 -methyl- 1,4-hexadiene=, 3,7-
dimethyl 1,6-
octadiene; 3,7-dimethyl 1,7-octadiene; and the inixed isomers of dihydro-
myrcene
and dihydro-cymene.
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c. Single ring alicyclic dienes such as: 1,4-cyclohexadiene; 1,5-
cyclooctadiene; 1,5-
cyclo-dodecadiene; 4-vinylcyclohexene; 1-allyl, 4-isopropylidene cyclohexane;
3-
allyl-cyclopentene; 4-allyl cyclohexene and 1-isopropenyl-4-(4-butenyl)
cyclohexane.
d. Multi-single ring alicyclic dienes such as: 4,4'-dicyclopentenyl and 4,4'-
dicyclohexenyl dienes.
e. Multi-ring alicyclic fused and bridged ring dienes such as:
tetrahydroindene; methyl
tetrahydroindene; dicyclopentadiene; bicyclo (2.2.1)-hepta 2,5-diene; alkyl,
alkenyl,
alkylidene, cycloalkenyl and cycloalkylidene norbomenes such as: ethyl
norbomene;
5- methylene- 6-methyl-2 -norbomene; 5-methylene-6, 6-dimethyl-2-norbomene; 5-
propenyl-2-norbornene; 5-(3-cyclopentenyl)-2-norbomene and 5-cyclohexylidene-2-
norbomene; norbornadiene; etc.
A compound containing at least one ethylenic bond and at least one, preferably
two,
carboxylic acid groups, or an anhydride group, or a polar group which is
convertible
into said carboxyl groups by oxidation or hydrolysis may be grafted on the
ethylene
coploymer. Preferred acid materials are (i) monounsaturated C4 to Clo
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; or (ii) derivatives of (i) such as anhydrides or C1 to
C5
alcohol derived mono- or diesters of (i). Upon reaction with the ethylene-
alpha-olefin
copolymer, the monounsaturation of the dicarboxylic acid, a.nhydride, or ester
becomes saturated. Thus, for example, maleic anhydride becomes a hydrocarbyl
substituted succinic anhydride.
Maleic anhydride or a derivative thereof is preferred as it does not appear to
homopolymerize appreciably but grafts onto the ethylene copolymer to give two
carboxylic acid functionalities. Such preferred materials have the generic
formula
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P a s
~ T \
0~ ~ 0
C
wherein R5 and R6 are the same or different and are hydrogen or a halogen.
Suitable
examples additionally include chloro-maleic anhydride, itaconic anhydride, or
the
corresponding dicarboxylic acids, such as maleic acid or fumaric acid or their
monoesters, etc.
As taught by U.S. Patent No. 4,160,739 and U.S. Patent No. 4,161,452, various
unsaturated comonomers may be grafted on the ethylene copolymer together with
the
unsaturated acid component, e.g. maleic anhydride. Such graft monomer systems
may
comprise one or a mixture of comonomers different from the unsaturated acid
component and which contain only one copolymerizable double bond and are
copolymerizable with said unsaturated acid component. Typically, such
comonomers
do not contain free carboxylic acid groups and are esters containing alpha,
beta-
ethylenic unsaturation in the acid or alcohol portion; hydrocarbons, both
aliphatic and
aromatic, containing alpha, beta-ethylenic unsaturation, such as the C4 to C12
alpha
olefins, for example isobutylene, hexene, nonene, dodecene, etc.; styrenes,
for
example styrene, alpha-methyl styrene, p-methyl styrene, p-sec. butyl styrene,
etc.;
and vinyl monomers, for example vinyl acetate, vinyl chloride, vinyl ketones
such as
methyl and ethyl vinyl ketone, etc. Comonomers containing functional groups
which
may cause crosslinking, gelation or other interfering reactions should be
avoided,
although minor amounts of such comonomers (up to about 10% by weight of the
comonomer system) often can be tolerated.
Specific useful copolymerizable comonomers include the following:
(A) Esters of saturated acids and unsaturated alcohols wherein the saturated
acids may
be monobasic or polybasic acids containing up to about 40 carbon atoms such as
the
following: acetic, propionic, butyric, valeric, caproic, stearic, oxalic,
malonic,
succinic, glutaric, adipic, pimelic, suberic, azelaic, sebacic, phthalic,
isophthalic,
14
CA 02548166 2009-05-04
terephthalic, hemimellitic, trimellitic, trimesic and the like, including
mixtures. The
unsaturated alcohols may be monohydroxy or polyhydroxy alcohols and may
contain
up to about 40 carbon atoms, such as the following: allyl, methallyl, crotyl,
1-
chloroallyl, 2-chloroallyl, cinnamyl, vinyl, methyl vinyl, 1-phenallyl,
butenyl,
propargyl, l-cyclohexene-3-ol, oleyl, and the like, including mixtures.
(B) Esters of unsaturated monocarboxylic acids containing up to about 12
carbon
atoms such as acrylic, methacrylic and crotonic acid, and an esterifying agent
containing up to about 50 carbon atoms, selected from saturated alcohols and
alcohol
epoxides. The saturated alcohols may preferably contain up to about 40 carbon
atoms
and include monohydroxy compounds such as: methanol, ethanol, propanol,
butanol,
2-ethylhexanol, octanol, dodecanol, cyclohexanol, cyclopentanol, neopentyl
alcohol,
and benzyi alcohol; and alcohol ethers such as the monomethyl or monobutyl
ethers
of ethylene or propylene glycol, and the like, including mixtures. The alcohol
epoxides include fatty alcohol epoxides, glycidol, and various derivatives of
alkylene
oxides, epichlorohydrin, and the like, including mixtures.
The components of the graft copolymerizable system are used in a ratio of
unsaturated
acid monomer component to comonomer component of about 1:4 to about 4:1,
preferably about 1.2 to about 2:1 by weight.
Further dispersant functionality may be incorporated into the OCP by reacting
with
polyamine or polyol, high functionality long chain hydrocarbyl dicarboxylic
acid
materials having a functionality of from about 1.2 to about 2 and short chain
hydrocarbyl substituted dicarboxylic acids, as described, for example, in US
Patent
No. 5,035,821.
Among the copolymers preferred are ethylene-propylene copolymers (the ratio of
ethylene:propylene is preferably about 3:1 to about 1:3), and styrene-isoprene
copolymers. Olefin copolymers are manufactured from ethylene and propylene by
means of Ziegler catalysts. The molecular weight of olefinic copolymers may
vary
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widely, but preferred copolymers are those having a molecular weight of from
about
30,000 to about 200,000, more preferably from about 40,000 to about 150,000.
Such preferred copolymers include nitrogen atom-containing polymers, for
example,
those obtained by copolymerizing or grafting, with an acidic component such as
maleic acid or anhydride thereof, onto an olefmic copolymer, followed by
forming
amide or imide linkages by reaction with polyamines.
Another such preferred copolymer is that obtained by oxidizing an olefinic
copolymer, followed by reacting the oxidized polymer with polyamines. Still
another
copolymer is that obtained by oxidizing an olefinic copolymer followed by
Mannich
condensation with formaldehyde and polyamines.
Another preferred copolymer is that obtained by copolymerizing olefins with a
nitrogen atom-containing monomer, or grafting a nitrogen atom-containing
monomer
onto an olefinic copolymer such as N-vinylpyrrolidone, N-vinylthiopyrrolidone,
a
dialkylaminoethyl methacrylate or the like (the content of nitrogen atom-
containing
monomer preferably being from about 0.1 to about 10 wt %).
In general, the VI Improver is present in the additive composition of the
present
invention in the range of from about 1 to about 99 wt %, preferably from about
5 to
about 95 wt %, and more preferably from about 10 to about 90 wt %, based on
the
total weight of the additive composition.
A further discussion of dispersant OCP VI improvers can be found, for exanple,
in
"Lubricant Additives; Chernistf y and Applications ", Leslie R. Rudnick,
Editor,
Chapters 5 and 10, Marcel Dekker, Inc, New York 2003.
THE HYDRATED ALKALI METAL BORATE
The additive composition of the present invention may optionally further
contain an
oil dispersion of hydrated alkali metal borate as described below.
Hydrated allcali metal borates are well lcnown in the art. Representative
patents
disclosing suitable borates and methods of manufacture inch.ide: U.S. Patent
Nos.
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WO 2005/059068 PCT/IB2004/004368
3,313,727; 3,819,521; 3,853,772; 3,912,643; 3,997,454; and 4,089,790.1"6
The hydrated alkali metal borates suitable for use in the present invention
can be
represented by the following general formula:
M209xB2O3=yH2O
wherein M is an alkali metal, preferably sodium or potassium; x is a number
from
about 2.5 to about 4.5 (both whole and fractional); and y is a number from
about 1.0
to about 4.8. More preferred are the hydrated potassium borates, particularly
the
hydrated-potassium triborates. The hydrated borate particles will generally
have a
mean particle size of less than 1 micron.
In the alkali metal borates employed in this invention, the ratio of boron to
alkali
metal will preferably range from about 2.5:1 to about 4.5:1.
Oil dispersions of hydrated alkali metal borates are generally prepared by
forming, in
deionized water, a solution of alkali metal hydroxide and boric acid,
optionally in the
presence of a small amount of the corresponding allcali metal carbonate. The
solution
is then added to a lubricant composition comprising an oil of lubricating
viscosity, a
dispersant and any optional additives to be included therein (e.g., a
detergent, or other
optional additives) to form an emulsion that is then dehydrated.
Because of their retention of hydroxyl groups on the borate complex, these
complexes
are referred to as "hydrated alkali metal borates" and compositions containing
oil/water emulsions of these hydrated alkali metal borates are referred to as
"oil
dispersions of hydrated alkali metal borates".
Preferred oil dispersions of alkali metal borates will have a boron to alkali
metal ratio
of from about 2.5:1 to about 4.5:1. In anotlier preferred embodiment, the
hydrated
allcali metal borate particles generally will have a mean particle size of
less than 1
micron. In this regard, it has been found that the hydrated alkali metal
borates
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WO 2005/059068 PCT/IB2004/004368
employed in this invention preferably will have a particle size where 90% or
greater
of the particles are less than 0.6 microns.
In the oil dispersion of hydrated alkali metal borate, the hydrated alkali
metal borate
will generally comprise from about 10 to about 75 wt %, preferably from about
25 to
about 50 wt %, more preferably from about 30 to about 40 wt % of the total
weight of
the oil dispersion of hydrated borate.
In general, when einployed, the oil dispersion of hydrated allcali metal
borate is
present in the additive composition of the invention in the range of from
about 10 to
about 90 wt %, based on the total weight of the additive composition.
The additive compositions and lubricant compositions of the present invention
can
further employ surfactants, detergents, other dispersants and other conditions
as
described below and known to those skilled in the art. Optionally, the
additive
compositions may contain an alkylaromatic or polyisobutenyl sulfonate.
The oil dispersions of hydrated alkali metal borates employed in this
invention
generally comprise a dispersant, an oil of lubricating viscosity, and
optionally a
detergent, that are further detailed below.
The dispersant employed in the oil dispersion of hydrated alkali metal borate
optionally employable in the present invention can be ashless dispersants such
as an
alkenyl succinimide, an alkenyl succinic anhydride, an alkenyl succinate
ester, and the
like, or mixtures of such dispersants.
Ashless dispersants are broadly divided into several groups. One such group is
directed to copolymers which contain a carboxylate ester with one or more
additional
polar function, including amine, amide, imine, imide, hydroxyl carboxyl, and
the like.
These products can be prepared by copolymerization of long chain alkyl
acrylates or
methacrylates with monomers of the above function. Such groups include alkyl
methacrylate-vinyl pyrrolidinone copolymers, alkyl methacrylate-
dialkylaminoethyl
methacrylate copolymers and the like. Additionally, high molecular weight
amides
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and polyamides or esters and polyesters such as tetraethylene pentamine,
polyvinyl
polysterarates and other polystearamides may be employed. Preferred
dispersants are
N-substituted long chain alkenyl succinimides.
Alkenyl succinimides are usually derived from the reaction of alkenyl succinic
acid or
anhydride and alkylene polyamines. These compounds are generally considered to
have the formula
R7 O
N Alk-(N-Allc)Z-NR9 R"
1 8
R
O
wherein R7 is a substantially hydrocarbon radical having a molecular weight
from
about 400 to about 3,000, that is, R7 is a liydrocarbyl radical, preferably an
alkenyl
radical, containing from about 30 to about 200 carbon atoms; Alk is an
alkylene
radical of from about 2 to about 10, preferably from about 2 to about 6,
carbon atoms,
R8, R9, and R10 are selected from a C1 to C4 alkyl or alkoxy or hydrogen,
preferably
hydrogen, and z is an integer from about 0 to about 10, preferably from about
0 to
about 3. The actual reaction product of alkylene succinic acid or anhydride
and
alkylene polyamine will comprise the mixture of compounds including succinamic
acids and succinimides. However, it is customary to designate this reaction
product as
a succinimide of the described formula, since this will be a principal
component of the
mixture. See, for example, U.S. Patent Nos. 3,202,678; 3,024,237; and
3,172,892.
These N-substituted alkenyl succinimides can be prepared by reacting maleic
anhydride with an olefinic hydrocarbon followed by reacting the resulting
alkenyl
succinic anhydride with the alkylene polyamine. The Rl radical of the above
formula,
that is, the alkenyl radical, is preferably derived from a polymer prepared
from an
olefin monomer containing from about 2 to about 5 carbon atoms. Thus, the
alkenyl
radical is obtained by polymerizing an olefin containing from about 2 to about
5
carbon atoms to form a hydrocarbon having a molecular weight ranging from
about
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WO 2005/059068 PCT/IB2004/004368
400 to about 3,000. Such olefin monomers are exemplified by ethylene,
propylene, 1-
butene, 2-butene, isobutene, and mixtures thereof.
The preferred polyalkylene amines used to prepare the succinimides are of the
fortnula:
N Alk~NR9R10
H2N A1k+
z
s
wherein z is an integer of from about 0 to about 10 and Alk, R8, R9, and R10
are as
defined above.
The alkylene amines include principally methylene amines, ethylene amines,
butylene
amines, propylene amines, pentylene amines, hexylene amines, heptylene amines,
octylene amines, other polymethylene amines and also the cyclic and the higher
homologs of such amines as piperazine and amino alkyl-substituted piperazines.
They
are exemplified specifically by ethylene diamine, triethylene tetraamine,
propylene
diamine, decamethyl diamine, octamethylene diamine, diheptamethylene triamine,
tripropylene tetraamine, tetraethylene pentamine, trimethylene diamine,
pentaethylene
hexamine, ditrimethylene triamine, 2-heptyl-3-(2-aminopropyl)-imidazoline,
4-methyl imidazoline, N,N-dimethyl-1,3-propane diamine, 1,3-bis(2-
aminoethyl)imidazoline, 1-(2-aminopropyl)-piperazine,
1,4-bis(2-aminoethyl)piperazine and 2-methyl-l-(2-aminobutyl)piperazine.
Higher
homologs such as are obtained by condensing two or more of the above-
illustrated
alkylene amines likewise are useful. ,
The ethylene amines are especially useful. They are described in some detail
under
the heading "Ethylene Arnines" in Encyclopedia of Chemical Technology, Kirk-
Otlim.er, Vol. 5, pp. 898-905 (Interscience Publishers, New York, 1950).
The ten.n "ethylene amine" is used in a generic sense to denote a class of
polyamines
conforming for the most part to the stnxcture
CA 02548166 2009-05-04
H2N(CH2CH2NH)aH
wherein a is an integer from about 1 to about 10.
Thus, it includes, for example, ethylene diamine, diethylene triamine,
triethylene
tetraamine, tetraethylene pentamine, pentaethylene hexamine, and the like.
Also included within the term "alkenyl succinimides" are post-treated
succinimides
such as post-treatment processes involving ethylene carbonate disclosed by
Wollenberg, et al., U.S. Patent No. 4,612,132; Wollenberg, et al., U.S. Patent
No.
4,746,446; and the like as well as other post-treatment processes.
Preferably, the dispersant component, such as a polyalkylene succinimide,
comprises
from about 2 to about 40 wt %, more preferably from about 5 to about 20 wt %,
and
even more preferably from about 5 to about 15 wt %, of the weight of the oil
dispersion of hydrated alkali metal borate.
Polyalkylene succinic anhydrides or a non-nitrogen containing derivative of
the
polyalkylene succinic anhydride (such as succinic acids, Group I and/or Group
II
mono- or di-metal salts of succinic acids, succininate esters formed by the
reaction of
a polyalkylene succinic anhydride, acid chloride or other derivative with an
alcohol,
and the like) are also suitable dispersants for use in the compositions of
this invention.
The polyalkylene succinic anhydride is preferably a polyisobutenyl succinic
anhydride. In one preferred embodiment, the polyalkylene succinic anhydride is
a
polyisobutenyl succinic anhydride having a number average molecular weight of
at
least 500, more preferably at least about 900 to about 3,000 and still more
preferably
from at least about 900 to about 2,300.
In another preferred embodiment, a mixture of polyalkylene succinic anhydrides
is
employed. In this embodiment, the mixture preferably comprises a low molecular
weight polyalkylene succinic anhydride component and a high molecular weight
21
CA 02548166 2009-05-04
polyalkylene succinic anhydride component. More preferably, the low molecular
weight component has a number average molecular weight of from about 500 to
below 1,000 and the high molecular weight component has a number average
molecular weight of from about 1000 to about 3,000. Still more preferably,
both the
low and high molecular weight components are polyisobutenyl succinic
anhydrides.
Alternatively, various molecular weights polyalkylene succinic anhydride
components
can be combined as a dispersant as well as a mixture of the other above
referenced
dispersants as identified above.
As noted above, the polyalkylene succinic anhydride is the reaction product of
a
polyalkylene (preferably polyisobutene) with maleic anhydride. One can use
conventional polyisobutene, or high methylvinylidene polyisobutene in the
preparation of such polyalkylene succinic anhydrides. One can use thermal,
chlorination, free radical, acid catalyzed, or any other process in this
preparation.
Examples of suitable polyalkylene succinic anhydrides are thermal PIBSA
(polyisobutenyl succinic anhydride) described in U.S. Patent No. 3,361,673;
chlorination PIBSA described in U.S. Patent No. 3,172,892; a mixture of
thermal and
chlorination PIBSA described in U.S. Patent No. 3,912,764; high succinic ratio
PIBSA described in U.S. Patent No. 4,234,435; PolyPIBSA described in U.S.
Patent
Nos. 5,112,507 and 5,175,225; high succinic ratio PoIyPIBSA described in U.S.
Patent Nos. 5,565,528 and 5,616,668; free radical PIBSA described in U.S.
Patent
Nos. 5,286,799, 5,319,030, and 5,625,004; PIBSA made from high
methylvinylidene
polybutene described in U.S. Patent Nos. 4,152,499, 5,137,978, and 5,137,980;
high
succinic ratio PIBSA made from high methylvinylidene polybutene described in
European Patent Application Publication No. EP 355 895; terpolymer PIBSA
described in U.S. Patent No. 5,792,729; sulfonic acid PIBSA described in U.S.
Patent
No. 5,777,025 and European Patent Application Publication No. EP 542 380; and
purified PIBSA described in U.S. Patent No. 5,523,417 and European Patent
Application Publication No. EP 602 863.
Preferably, the polyalkylene succinic anhydride or other dispersant component
comprises from about 2 to about 40 wt %, more preferably from about 5 to about
20
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WO 2005/059068 PCT/IB2004/004368
wt %, and even more preferably from about 5 to about 15 wt %, of the weight of
the
oil dispersion of hydrated alkali metal borate.
Typically, in the oil dispersion of hydrated alkali metal borate, the hydrated
alkali
metal borate is in a ratio of at least 2:1 relative to the polyalkylene
succinic anhydride
or other dispersant, while preferably being in the range of 2:1 to about 10:1.
In a
more preferred embodiment the ratio is at least 5:1. In anotlier preferred
embodiment,
mixtures as defined above of the polyalkylene succinic anhydrides are
employed.
The oil dispersion of hydrated alkali metal borate which is optionally
employed in the
additive compositions of the present invention may optionally contain a
detergent.
There are a number of materials that are suitable as detergents for the
purpose of this
invention. These materials include phenates (high overbased or low overbased),
high
overbased phenate stearates, phenolates, salicylates, phosphonates,
thiophosphonates
and sulfonates and mixtures thereof. Preferably, sulfonates are used, such as
high
overbased sulfonates, low overbased sulfonates, or phenoxy sulfonates. In
addition
the sulfonic acids themselves can also be used.
The sulfonate detergent is preferably an alkali or alkaline earth metal salt
of a
hydrocarbyl sulfonic acid having from about 15 to about 200 carbons.
Preferably the
term "sulfonate" encompasses the salts of sulfonic acid derived from petroleum
products. Such acids are well known in the art. They can be obtained by
treating
petroleum products with sulfuric acid or sulfur trioxide. The acids thus
obtained are
lrnown as petroleum sulfonic acids and the salts as petroleum sulfonates. Most
of the
petroleum products which become sulfonated contain an oil-solubilizing
hydrocarbon
group. Also included within the meaning of "sulfonate" are the salts of
sulfonic acids
of synthetic alkyl aryl compounds. These acids also are prepared by treating
an alkyl
aryl compound with sulfuric acid or sulfur trioxide. At least one alkyl
substituent of
the aryl ring is an oil-solubilizing group, as discussed above. The acids thus
obtained
are lcnown as allcyl aryl sulfonic acids and the salts as alkyl aryl
sulfonates. The
sulfonates where the allcyl is straight-chain are the well-known linear
alkylaryl
sulfonates.
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The acids obtained by sulfonation are converted to the metal salts by
neutralizing with
a basic reacting alkali or alkaline earth metal compound to yield the Group I
or Group
II metal sulfonates. Generally, the acids are neutralized with an alkali metal
base.
Alkaline earth metal salts are obtained from the alkali metal salt by
metathesis.
Alternatively, the sulfonic acids can be neutralized directly with an alkaline
earth
metal base. The sulfonates can then be overbased, although, for purposes of
this
invention, overbasing is not necessary. Overbased materials and methods of
preparing
such materials are well known to those skilled in the art. See, for example,
LeSuer
U.S. Patent No. 3,496,105, issued Feb. 17, 1970, particularly columns 3 and 4.
The sulfonates are present in the oil dispersion in the form of alkali and/or
alkaline
earth metal salts, or mixtures thereof. The alkali metals include lithium,
sodium and
potassium. The alkaline earth metals include magnesium, calcium and barium, of
which the latter two are preferred.
Particularly preferred, however, because of their wide availability, are salts
of the
petroleum sulfonic acids, particularly the petroleum sulfonic acids which are
obtained
by sulfonating various hydrocarbon fractions such as lubricating oil fractions
and
extracts rich in aromatics which are obtained by extracting a hydrocarbon oil
with a
selective solvent, which extracts may, if desired, be alkylated before
sulfonation by
reacting them with olefins or alkyl chlorides by means of an alkylation
catalyst;
organic polysulfonic acids such as benzene disulfonic acid which may or may
not be
alkylated; and the like.
The preferred salts for use in the present invention are those of alkylated
aromatic
sulfonic acids in which the alkyl radical or radicals contain at least about 8
carbon
atoms, for example from about 8 to about 22 carbon atoms. Another preferred
group
of sulfonate starting materials are the aliphatic-substituted cyclic sulfonic
acids in
which the aliphatic substituents or substituents'contain a total of at least
12 carbon
atoms, such as the alkyl aryl sulfonic acids, alkyl cycloaliphatic sulfonic
acids, the
alkyl heterocyclic sulfonic acids and aliphatic sulfonic acids in which the
aliphatic
radical or radicals contain a total of at least 12 carbon atoms. Specific
examples of
these oil-soluble sulfonic acids include petroleum sulfonic acids, mono- and
poly-
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wax-substituted naphthalene sulfonic acids, substituted sulfonic acids, such
as cetyl
benzene sulfonic acids, cetyl phenyl sulfonic acids, and the like, aliphatic
sulfonic
acid, such as paraffin wax sulfonic acids, hydroxy-substituted paraffin wax
sulfonic
acids, etc., cycloaliphatic sulfonic acids, petroleum naphthalene sulfonic
acids, cetyl
cyclopentyl sulfonic acid, mono- and poly-wax-substituted cyclohexyl sulfonic
acids,
and the like. The term "petroleum sulfonic acids" is intended to cover all
sulfonic
acids that are derived directly from petroleum products.
Typical Group II metal sulfonates suitable for use in the present invention
include the
metal sulfonates exemplified as follows: calcium white oil benzene sulfonate,
barium
white oil benzene sulfonate, magnesium white oil benzene sulfonate, calcium
dipolypropene benzene sulfonate, barium dipolypropene benzene sulfonate,
magnesium dipolypropene benzene sulfonate, calcium mahogany petroleum
sulfonate, barium mahogany petroleum sulfonate, magnesium mahogany petroleum
sulfonate, calcium triacontyl sulfonate, magnesium triacontyl sulfonate,
calcium
lauryl sulfonate, barium lauryl sulfonate, magnesium lauryl sulfonate, etc.
The
concentration of metal sulfonate that may be employed may vary over a wide
range,
depending upon the concentration of alkali metal borate particles. When
present,
however, the detergent concentration will generally range from about 0.2 to
about 10
wt % and preferably from about 3 to about 7 wt %, based on the total weight of
the oil
dispersion of hydrated borate. In addition, the compositions of this invention
may
contain a mixture of both a metal sulfonate and an ashless dispersant, as
described
above, where the ratio is a factor of achieving the proper stability of the
oil dispersion
of hydrated alkali metal borate.
The oil of lubricating viscosity used to form the oil dispersions of hydrated
alkali
metal borate may be any hydrocarbon-based lubricating oil or a synthetic base
oil
stock. Likewise, these lubricating oils can be added to the oil dispersions
and additive
compositions containing them, as described herein, in additional amounts, to
form
finished lubricating oil compositions. The hydrocarbon-based lubricating oils
may be
derived from synthetic or natural sources and may be paraffinic, naphthenic or
aromatic base, or mixtures thereof. The diluent oil can be natural or
synthetic, and can
be different viscosity grades.
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in the oil dispersion of hydrated alkali metal borate, the lubricating oil
typically
comprises from about 30 to about 70 wt %, more preferably from about 45 to
about
55 wt %, based on the total weight of the oil dispersion of hydrated alkali
metal
borate.
When employed the oil dispersion of hydrated alkali metal borate is present in
the
additive composition of the present invention in the range of from about 1 to
about 99
wt %, preferably from about 5 to about 95 wt %, based on the total weight of
the
additive composition.
FORMULATIONS
The additive composition of the present invention containing the oil
dispersion of
hexagonal boron nitride and VI improver, and optionally, the oil dispersion of
hydrated alkali metal borate, may be blended further with additional additives
to form
additive packages containing the present additive compositions. These additive
packages typically comprise from about 10 to about 80 wt % of the additive
composition of the present invention described above and from about 90 to
about 20
wt % of one or more of conventional additives selected from the group
consisting of
ashless dispersants (0-10 wt %), detergents (0-5 wt %), sulfurized
hydrocarbons (0-40
wt %), dialkyl hydrogen phosphates (0-15 wt %), zinc dithiophosphates (0-20 wt
%),
alkyl ammonium phosphates and/or thio- dithiophosphates (0-20 wt %),
phosphites (0
to 10 wt %) fatty acid esters of polyalcohols (0-l Owt %), 2,5-
dimercaptothiadiazole
(0-5 wt %), benzotriazole (0-5 wt %), dispersed molybdenum disulfide (0-5 wt
%),
foam inhibitors (0-2 wt %), and imidazolines (0-10 wt %) and the like wherein
each
wt % is based on the total weight of the additive composition.
Fully formulated finished lubricating oil compositions of this invention can
be
formulated from these additive packages upon further blending witli an oil of
lubricating viscosity. Preferably, the additive package described above is
added to a
base oil of lubricating viscosity in an amount of from about 1 to about 40 wt
%,
preferably from about 2 to about 20 wt %, to provide for the finished
lubricating oil
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composition wherein the wt % of the additive package is based on the total
weight of
the lubricating oil composition.
A variety of other additives can be present in lubricating oils of the present
invention.
These additives include antioxidants, rust inhibitors, corrosion inhibitors,
extreme
pressure agents, antifoam agents, other anti-wear agents, and a variety of
other well-
known additives in the art.
EXAMPLES
The invention will be further illustrated by the following examples, which set
forth
particularly advantageous embodiments. While the examples are provided to
illustrate
the present invention, they are not intended to limit it.
Example 1
The additive composition of the present invention was evaluated in a
lubricating oil
for its anti-sticking properties following a test using an SAE No. 2 bench,
which
evaluates transmission fluids during synchronization. The friction pairs used
in this
bench comprised a brass synchronizer ring and a steel gear cone.
During each cycle of the test, the cone is rotating, at a given speed, then
the ring
moves along the.axis of the cone for its braking until it is blocked. At the
end of each
cycle, the ring is disengaged.
If sticking occurs, a sticking torque is measured when rotation of the cone is
resumed.
During the test, the lubricating oil and the metal parts are heated to a
temperature
between about 60 C and about 90 C. The contact pressure is about 20 MPa and
the
initial sliding speed is 1.6 m/s.
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The anti-sticking coefficient for this test was calculated as follows:
Anti-sticking coefficient = 1- (No of cycles with stickin~)
(Total No, of cycles in test)
Accordingly, an anti-sticking coefficient of 0 indicates the presence of cone
on ring
sticking during every cycle of the test. Conversely, an anti-sticking
coefficient of 1
indicates no sticking at all was observed over the entire duration of the
test. Thus, the
higher the anti-sticking coefficient, up to a maximum of 1, the better the
anti-sticking
performance of the lubricating oil.
The test lubricating oil compositions were formulated as follows, all the oils
formulated have the same viscosity (about of 9 cSt):
Lubricant Composition 1
Lubricant composition 1 was prepared containing the following:
a) 10 wt % of an oil dispersion of hexagonal boron nitride, wherein the oil
dispersion contained about 10 wt % of the hexagonal boron nitride solids,
dispersed in a 150 N neutral oil containing a stabilizing agent,
b) 12 wt % of a long chain polymethacrylate VI Improver sold under the name
Viscoplex 0-113 (available from RohMax Additives GmbH, Darmstadt,
Germany), and
c) 78 wt % of a 50/50 mixture of neutral oil (150N plus 600N) and synthetic
polyalphaolefin oil.
Lubricant Composition 2
Lubricant composition 2 was prepared containing the following:
a) 10 wt % of an oil dispersion of hexagonal boron nitride, wherein the oil
dispersion contained about 10 wt % of the hexagonal boron nitride solids,
dispersed in a 150 N neutral oil containing a stabilizing agent,
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b) 12 wt % of a dispersant long chain polymethacrylate VI Improver sold under
the name Viscoplex 0-110 (available from RohMax Additives GmbH,
Darmstadt, Germany), and
c) 78 wt % of a 50150 mixture of neutral oil (150N plus 600N) and synthetic
polyalphaolefin oil.
Lubricant Composition 3
Lubricant composition 3 was prepared containing the following:
a) 10 wt % of an oil dispersion of hexagonal boron nitride, wherein the oil
dispersion contained about 10 wt % of the hexagonal boron nitride solids,
dispersed in a 150 N neutral oil containing a stabilizing agent,
b) 12 wt % of a short chain polymethacrylate VI Improver sold under the name
Viscoplex 0-030 (available from RohMax Additives GmbH, Darmstadt,
Germany), and
c) 78 wt % of a 50/50 mixture of neutral oil (150N plus 600N) and synthetic
polyalphaolefin oil.
Lubricant Composition 4
Lubricant composition 4 was prepared containing the following:
a) 10 wt / of an oil dispersion of hexagonal boron nitride, wherein the oil
dispersion contained about 10 wt % of the hexagonal boron nitride solids,
dispersed in a 150 N neutral oil containing a stabilizing agent,
b) 12 wt % of a dispersant ethylene-propylene olefin copolyiner VI Improver
with a weight average molecular weight of about 39,000 (Paratone 8500
available from Chevron Oronite Company, LLC, San Ramon, California), and
c) 78 wt % of a 50/50 mixture of neutral oil (150N plus 600N) and synthetic
polyalphaolefin oil.
Lubricant Composition 5
Lubricant composition 5 was prepared containing the following:
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a) 7 wt % of an oil dispersion of hydrated potassium triborate, wherein the
oil
dispersion contained about 30 wt % of the hydrated potassium triborate,
dispersed in a 150 N neutral oil,
b) 10 wt % of an oil dispersion of hexagonal boron nitride, wherein the oil
dispersion contained about 10 wt % of the hexagonal boron nitride solids,
dispersed in a 150 N neutral oil containing a stabilizing agent,
c) 12 wt % of a long chain polymethacrylate VI Improver sold under the name
Viscoplex 0-113 (available from RohMax Additives GmbH, Darmstadt,
Germany), and
d) 71 wt % of a 50/50 mixture of neutral oil (150N plus 600N) and synthetic
polyalphaolefin oil.
Lubricant Composition A (comparative)
Comparative lubricant composition A was prepared containing the following:
a) 7 wt % of an oil dispersion of hydrated potassium triborate, wherein the
oil
dispersion contained about 30 wt % of the hydrated potassiuin triborate,
dispersed in a 150 N neutral oil, and
b) 93 wt % of a 50/50 mixture of neutral oil (150N plus 600N) and synthetic
polyalphaolefin oil.
Lubricant Composition B (comparative)
Comparative lubricant composition B was prepared containing the following:
a) 10 wt % of an oil dispersion of hexagonal boron nitride, wherein the oil
dispersion contains about 10 wt % of the hexagonal boron nitride solids,
dispersed in a 150 N neutral oil containing a stabilizing agent, and
b) 90 wt % of a 50/50 mixture of neutral oil (150N plus 600N) and synthetic
polyalphaolefin oil.
Lubricant Composition C (comparative):
Comparative lubricant composition C was prepared containing the following:
CA 02548166 2006-06-01
WO 2005/059068 PCT/IB2004/004368
a) 10 wt % of an oil dispersion of hexagonal boron nitride, wherein the oil
dispersion contained about 10 wt % of the hexagonal boron nitride solids,
dispersed in a 150 N neutral oil containing a stabilizing agent,
b) 12 wt % of a non-dispersant type ethylene-propylene olefin copolymer VI
Improver with a weight average molecular weight of about 90,000
(Paratone 8002 available from Chevron Oronite Company, LLC, San Ramon,
California), and
c) 78 wt % of a 50/50 mixture of neutral oil (150N plus 600N) and synthetic
polyalphaolefin oil.
Lubricant Composition D (comparative)_
Comparative lubricant composition D was prepared containing the following:
a) 10 wt % of an oil dispersion of hexagonal boron nitride, wherein the oil
dispersion contained about 10 wt % of the hexagonal boron nitride solids,
dispersed in a 150 N neutral oil containing a stabilizing agent,
b) 0.5 wt % of a polyisobutenyl mono-succinimide, and
c) 89.5 wt % of a 50/50 mixture of neutral oil (150N plus 600N) and synthetic
polyalphaolefin oil.
Lubricant Composition E (comparative):
Comparative lubricant composition E was prepared containing the following:
a) 10 wt % of an oil dispersion of hexagonal boron nitride, wherein the oil
dispersion contained about 10 wt % of the hexagonal boron nitride solids,
dispersed in a 150 N neutral oil containing a stabilizing agent
b) 0.5 wt % of a polyisobutenyl bis-succinimide, and
c) 89.5 wt % of a 50/50 mixture of neutral oil (150N plus 600N) and synthetic
polyalphaolefin oil.
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Table 1
Sample No. of Cycles Total No. of Anti-sticking
with Cone on Cycles coefficient
Ring Sticking
Base oil 5000 5000 0
Comparative Composition A
8100 8100 0
Comparative Composition B
6600 6600 0
Comparative Composition C 5700 5700 0
Comparative Composition D 6400 6400 0
Comparative Composition E 8100 8100 0
Composition 1 500 7100 0.93
1050 5600 0.81
Composition 2 100 6800 0.99
Composition 3 1200 6850 0.82
Composition 4 200 20000 0.99
Composition 5 650 20000 0.97
The above data demonstrates that the additive composition of the present
invention
provides significant anti-sticking performance and shows a marlced improvement
over
the comparative compositions.
From the foregoing description, various modifications and changes in the above-
described invention will occur to those skilled in the art. All such
modifications
coming within the scope of the appended claims are intended to be included
therein.
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