Note: Descriptions are shown in the official language in which they were submitted.
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TITLE
Composition and Method for Lubricating Automotive Gears, Axles and Bearings
BACKGROUND
[0001] The disclosed technology relates to a lubricant composition
for automotive
gears, axles and bearings, the lubricant composition containing an oil of
lubricating viscosity
and an oil-soluble titanium compound in place of boron compounds, as well as a
method of
obtaining thermal stability performance in automotive gears, axles and
bearings without the
boron content that is typical, by lubricating such automotive gears, axles and
bearings with a
lubricant composition containing an oil-soluble titanium compound.
[0002] Driveline power transmitting devices (such as gears or
transmissions) present
highly challenging technological problems and solutions for satisfying the
multiple and often
conflicting lubricating requirements, while providing durability and
cleanliness.
[0003] Lubricants are expected to be able to pass thermal stability
tests, e.g. the L-
60-1 test (ASTM D5704) (comprising a 50 hr test for axle oils). The lubricant
should be
able to provide adequate thermal stability as well as viscosity control to
pass these tests.
[0004] In order to prepare lubricants which are thermally stable, it
has become
common practice to add boron compounds to the lubricating oil, such as borated
dispersants.
[0005] It would be beneficial to provide lubricant compositions
substantially free of,
or even free of, boron compounds for automotive gears, axles and bearings.
SUMMARY
[0006] It has been found that the use of titanium compounds can
replace the typical
boron containing materials in lubricant compositions for automotive gears,
axles and
bearings that contain amine-containing phosphorus antiwear agents, while still
providing at
least equivalent, if not improved, thermal stability performance. This finding
was surprising,
as the prevailing understanding has been that boron compounds were required
for such
stability.
[0007] Thus, one aspect of the disclosed technology is related to a
lubricant composi-
tion for an automotive gear, axle, or bearing, as evidenced by a total sulfur
level of the lub-
.. ricant of about 0.75 to about 5 wt.% based on the weight of the lubricant
composition (re-
ferred to hereinbelow as an automotive gear oil), containing an oil of
lubricating viscosity,
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an amine-containing phosphorus antiwear agent and an oil-soluble titanium
compound (also
referred to as "titanium compound" for short), where the automotive gear oil
is substantially
free, or free, of boron.
[0008]
The titanium compound is not particularly limited, but it was found that
the
addition of titanium (IV) alkoxides, such as titanium (IV) 2-ethylhexoxide, to
an automotive
gear oil showed unexpected thermal stability performance.
[0009]
The titanium compound can be included in the automotive gear oil at levels
that deliver greater than 200 ppm of titanium to the lubricant composition.
[0010]
In addition to an amine-containing phosphorus antiwear agent, the
automotive
gear oil can also contain other additives, including other, non-amine
containing, phosphorus
compounds.
[0011]
Another aspect of the current technology includes a method of lubricating
an
automotive gear (such as an automotive gear, axle or bearing), with the
automotive gear oil
as disclosed herein.
DETAILED DESCRIPTION
[0012]
Various preferred features and embodiments will be described below by way
of non-limiting illustration. One aspect of the invention is an automotive
gear oil containing
an oil of lubricating viscosity, an amine-containing phosphorus antiwear
agent, and an oil-
soluble titanium compound, and being substantially free, or free, of boron. By
substantially
free, it is meant that the composition contains less than 50 ppm boron, or
less than 30 ppm,
or even less than 10 ppm or 5 ppm, or even less than 1 ppm boron.
Oil of Lubricating Viscosity
[0013]
One component of the disclosed technology is an oil of lubricating
viscosity, also
referred to as a base oil. The base oil may be selected from any of the base
oils in Groups I-
V of the American Petroleum Institute (API) Base Oil Interchangeability
Guidelines (2011),
namely
Base Oil Category Sulfur (%) Saturates (%) Viscosity Index
Group I >0.03 and/or <90 80 to less than 120
Group II <0.03 and >90 80 to less than 120
Group III <0.03 and >90 >120
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Group IV All polyalphaolefins (PA0s)
Group V All others not included in Groups I, II, III or IV
[0014] Groups I, II and III are mineral oil base stocks. Other
generally recognized
categories of base oils may be used, even if not officially identified by the
API: Group II+,
referring to materials of Group II having a viscosity index of 110-119 and
lower volatility
than other Group II oils; and Group III+, referring to materials of Group III
having a viscosity
index greater than or equal to 130. The oil of lubricating viscosity can
include natural or
synthetic oils and mixtures thereof. Mixtures of mineral oil and synthetic
oils, e.g., polyal-
phaolefin oils and/or polyester oils, may be used.
[0015] The oils employed in the composition are not particularly limited
and can in-
clude a kinematic viscosity at 100 C by ASTM D445 of 1 to 40, or 1 to 30, or
even 1 to 15
or 20, or 1.25 to 10 mm2/s. In some embodiments the oil of lubricating
viscosity can have a
kinematic viscosity at 100 C by ASTM D445 of 1.5 to 7.5, or 2 to 7, or 2.5 to
6.5, or 3 to 6
mm2/s. In one embodiment the oil of lubricating viscosity comprises a poly
alpha olefin hay-
ing a kinematic viscosity at 100 C by ASTM D445 of 1.5 to 7.5 mm2/s or any of
the other
aforementioned ranges.
Amine-Containing Phosphorus Ant/wear Agent
[0016] Amine-containing phosphorus antiwear agents can include, for
example,
amine salts of phosphoric acid esters; dialkyl mono-thio and di-thio
phosphoric acid esters;
and mono-alkyl or di-alkyl phosphites or phosphonates; and mixtures thereof.
The amine
salt of the phosphoric acid ester may comprise any of a variety of chemical
structures. In
particular, a variety of structures are possible when the phosphoric acid
ester compound
contains one or more sulfur atoms, that is, when the phosphorus-containing
acid is a thio-
phosphoric acid ester, including mono- or dithiophosphoric acid esters. A
phosphoric acid
ester may be prepared by reacting a phosphorus compound such as phosphorus
pentoxide
with an alcohol. A dithiophosphoric acid ester may be prepared by reacting
phosphorus
pentasulfide with an alcohol. Suitable alcohols include those containing up to
30 or to 24,
or to 12 carbon atoms, including primary or secondary alcohols such as
isopropyl, butyl,
amyl, s-amyl, 2-ethylhexyl, hexyl, cyclohexyl, octyl, decyl and oleyl
alcohols, as well as
any of a variety of commercial alcohol mixtures having, e.g., 8 to 10, 12 to
18, or 18 to 28
carbon atoms. Polyols such as diols may also be used. The amines which may be
suitable
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for use as the amine salt include primary amines, secondary amines, tertiary
amines, as well
as diamines, and mixtures thereof, including amines with at least one
hydrocarbyl group,
or, in certain embodiments, two or three hydrocarbyl groups having, e.g., 2 to
30 or 6 to
12, or 8 to 26 or 10 to 20 or 13 to 19 carbon atoms.
[0017] In
one embodiment, sulfur containing amine phosphate salts may be prepared
by reacting an alkylthiophosphate with an epoxide or a polyhydric alcohol,
such as glycerol.
This reaction product may be used alone, or further reacted with a phosphorus
acid, anhy-
dride, or lower ester. The epoxide is generally an aliphatic epoxide or a
styrene oxide.
Examples of useful epoxides include ethylene oxide, propylene oxide, butene
oxide, octene
oxide, dodecene oxide, styrene oxide, etc. Ethylene oxide and propylene oxide
are pre-
ferred. The glycols may be aliphatic glycols having from 2 to about 12, or
from 2 to about
6, or from 2 or 3 carbon atoms. Glycols include ethylene glycol, propylene
glycol, and the
like. The alkylthiophosphate, glycols, epoxides, inorganic phosphorus reagents
and meth-
ods of reacting the same are described in U.S. Pat. Nos. 3,197,405 and
3,544,465 which are
.. incorporated herein by reference for their disclosure to these.
[0018]
In one embodiment, the amine-containing phosphorus antiwear agent can be
sub-
stantially sulfur-free. Examples include the amine salt of a phosphate
hydrocarbon ester
prepared by reaction between phosphorus pentoxide with an alcohol (having 4 to
18 carbon
atoms), followed by a reaction with a primary (e.g., 2-ethylhexylamine or
oleylaminopropyl
amine), secondary (e.g., dimethylamine), or tertiary (e.g.,
dimethyloleylamine) amine to
form an amine salt of a phosphate hydrocarbon ester.
[0019]
Another example of an amine-phosphate antiwear agent is a substantially sul-
fur-free alkyl phosphate amine salt having at least 30 mole percent of the
phosphorus atoms
in an alkyl pyrophosphate structure (sometimes referred to as the POP
structure), as opposed
to an orthophosphate (or monomeric phosphate) structure, as shown, for
example, in the fol-
lowing formula R10(02)POP(02)0R1.(R23)NW, or variants thereof, where, each R'
is inde-
pendently an alkyl group of 3 to 12 carbon atoms, and each R2 is independently
hydrogen or
a hydrocarbyl group or an ester-containing group, or an ether-containing
group, provided that
at least one R2 group is a hydrocarbyl group or an ester-containing group or
an ether-contain-
ing group (that is, not NH3).
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[0020] The amount of the amine-containing phosphorus antiwear agent
in the auto-
motive gear oil may be 0.1 to 5 wt.%. Alternative amounts of the amine-
containing phos-
phorus antiwear agent may be 0.2 to 3 wt.%, or 0.2 to 2.5 wt.%, or 0.2 to 2
wt.%, or 1 to 2
wt.%, or 0.3 to 1.9 wt.%, or 0.4 to 1.8 wt.%, or 0.4 to 1.7 wt.%. The amount
may be suitable
5 to provide phosphorus to the automotive gear oil in an amount of 200 to
3000 parts per million
by weight (ppm), or 250 to 2750, or 300 to 2500, or 350 to 2250, or 400 to
2000 ppm, or 600
to 1500 ppm, or 700 to 1100 ppm, or 1100 to 1800 ppm.
Oil-Soluble Titanium Compound
[0021] The oil-soluble titanium compound can also be referred to
more generally as
a hydrocarbon-soluble titanium compound. By "oil-soluble" or "hydrocarbon
soluble" it is
meant a material which will dissolve or disperse on a macroscopic or gross
scale in an oil
or hydrocarbon, as the case may be, typically a mineral oil, such that a
practical solution or
dispersion can be prepared. In order to prepare a useful lubricant
formulation, the titanium
compound should not precipitate or settle out over a course of several days or
weeks, and
preferably months or years. Such materials may exhibit true solubility on a
molecular scale
or may exist in the form of agglomerations of varying size or scale, provided
however that
they have dissolved or dispersed on a gross scale.
[0022] The nature of the oil-soluble titanium compound can be
diverse. Among the
titanium compounds that may be used in the lubricating compositions are
various Ti (IV)
compounds such as titanium (IV) sulfide; titanium (IV) nitrate; titanium (IV)
alkoxides
such as titanium methoxide, titanium ethoxide, titanium propoxide, titanium
isopropoxide,
titanium butoxide; titanium (IV) 2-ethylhexoxide; and titanium (IV)
(triethanolaminato)iso-
propoxide; and other titanium compounds or complexes including but not limited
to tita-
nium phenates; titanium carboxylates such as titanium (IV) 2-ethyl-1-3-
hexanedioate or
titanium citrate or titanium oleate. Other forms of titanium that may be
employed include
titanium phosphates such as titanium dithiophosphates (e.g.,
dialkyldithiophosphates) and
titanium sulfonates (e.g., alkylsulfonates), or, generally, the reaction
product of titanium
compounds with various acid materials to form salts, especially oil-soluble
salts. Titanium
compounds can thus be derived from, among others, organic acids, alcohols, and
glycols.
Titanium compounds may also exist in dimeric or oligomeric form, containing Ti-
-0--Ti
structures. Such titanium compounds are commercially available or can be
readily prepared
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by appropriate synthesis techniques which will be apparent to the person
skilled in the art.
Titanium compounds may exist at room temperature as a solid or a liquid,
depending on the
particular compound, and may also be provided in a solution form in an
appropriate inert
solvent.
[0023] In embodiments, the titanium can be supplied as a Ti-modified
dispersant,
such as a succinimide dispersant. Such materials may be prepared by forming a
titanium
mixed anhydride between a titanium alkoxide and a hydrocarbyl-substituted
succinic anhy-
dride, such as an alkenyl- (or alkyl) succinic anhydride. The resulting
titanate-succinate
intermediate may be used directly or it may be reacted with any of a number of
materials,
such as (a) a polyamine-based succinimide/amide dispersant having free,
condensable -NH
functionality; (b) the components of a polyamine-based succinimide/amide
dispersant, i.e.,
an alkenyl- (or alkyl-)succinic anhydride and a polyamine, (c) a hydroxy-
containing poly-
ester dispersant prepared by the reaction of a substituted succinic anhydride
with a polyol,
aminoalcohol, polyamine, or mixtures thereof. Alternatively, the titanate-
succinate inter-
mediate may be reacted with other agents such as alcohols, aminoalcohols,
ether alcohols,
polyether alcohols or polyols, or fatty acids, and the product thereof either
used directly to
impart titanium to a lubricant, or else further reacted with the succinic
dispersants as de-
scribed above. As an example, 1 part (by mole) of tetraisopropyl titanate may
be reacted
with 2 parts (by mole) of a polyisobutene-substituted succinic anhydride at
140-150 C for
5 to 6 hours to provide a titanium modified dispersant or intermediate. The
resulting mate-
rial (30 g) may be further reacted with a succinimide dispersant from
polyisobutene-substi-
tuted succinic anhydride and a polyethylenepolyamine mixture (127 g+diluent
oil) at 150
C for 1.5 hours, to produce a titanium-modified succinimide dispersant.
[0024] In another embodiment, the titanium can be supplied as a
tolyltriazole oligo-
mer salted with and/or chelated to titanium. The surface active properties of
the tolyltriazole
allow it to act as a delivery system for the titanium, imparting the titanium
performance
benefits described herein, as well as the copper deactivating performance of
tolyltriazole.
In one embodiment, this material can be prepared by first combining
tolyltriazole (1.5 eq)
and formaldehyde (1.57 eq) in an inert solvent followed by addition of
diethanolamine (1.5
eq) and then hexadecyl succinic anhydride (1.5 eq) and a catalytic amount of
methanesul-
fonic acid, while heating and removing water of condensation. This
intermediate can be
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reacted with titanium isopropoxide (0.554 eq) at 60 C, followed by vacuum
stripping to
provide a red viscous product.
[0025] Other forms of titanium can also be provided, such as surface-
modified tita-
nium dioxide nanoparticles, as described in greater detail in Q. Xue et al.,
Wear 213, 29-
32, 1997 (Elsevier Science S.A.), which discloses TiO2 nanoparticles with an
average di-
ameter of 5 nm, surface modified with 2-ethylhexoic acid. Such nanoparticles
capped by
an organic hydrocarbyl chain are said to disperse well in non-polar and weakly
polar or-
ganic solvents. Their synthesis is described in greater detail by K. G.
Severin et al. in Chem.
Mater. 6, 8990-898, 1994.
[0026] In one embodiment, the titanium is not a part of or affixed to a
long-chain
polymer, that is, a high molecular weight polymer. Thus, the titanium species
may, in these
circumstances, have a number average molecular weight of less than 150,000 or
less than
100,000 or 30,000 or 20,000 or 10,000 or 5000, or 3000 or 2000, e. g, about
1000 or less
than 1000. Non-polymeric species providing the titanium as disclosed above
will typically
be below the molecular weight range of such polymers. For example, a titanium
tetraalkox-
ide such as titanium isopropoxide may have a number average molecular weight
of 1000 or
less, or 300 or less, as may be readily calculated. A titanium-modified
dispersant may in-
clude a hydrocarbyl substituent with a number average molecular weight of 3000
or less or
2000 or less, e.g., about 1000.
[0027] The amount of titanium (that is titanium atom as opposed to titanium
com-
pound) present in the automotive gear oil may typically be greater than 200
parts per million
by weight (ppm), or greater than 250 ppm, or greater than 300 or 325 ppm. In
some em-
bodiments, the titanium compound may be present at from about 200 to about
2000 ppm,
or from 200 or 250 to about 1500 ppm or even about 300 to about 1250 or even
about 325
or 350 to about 900 or 1000 ppm.
[0028] These limits may vary with the particular system investigated
and may be
influenced to some extent by the anion or complexing agent associated with the
titanium.
Also, the amount of the particular titanium compound to be employed will
depend on the
relative weight of the anionic or complexing groups associated with the
titanium. Titanium
isopropoxide, for instance, is typically commercially supplied in a form which
contains
16.8% titanium by weight. Thus, if amounts of 20 to 100 ppm of titanium are to
be provided,
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about 119 to about 595 ppm (that is, about 0.01 to about 0.06 wt.%) of
titanium isopropox-
ide would be used, and so on.
[0029]
In certain embodiments, the titanium compound may be selected from the
group consisting of titanium alkoxides, titanium modified dispersants,
titanium salts of ar-
omatic carboxylic acids (such as benzoic acid or alkyl-substituted benzoic
acids), and tita-
nium salts of sulfur-containing acids (such as those of the formula R--S--R--
0O2H, where
R is a hydrocarbyl group and R' is a hydrocarbylene group).
Other Additives
[0030]
An automotive gear oil, as used herein, refers to a lubricant composition
hay-
ing sufficient levels of additive to lubricate an automotive gear, such as a
gear, bearing or
axle. In this regard, automotive gear oils can be distinguished from other
lubricants, such as
engine oil lubricants, based on levels of sulfur and phosphorus.
[0031]
The automotive gear oil can have a total sulfur level of about 0.75 to
about 5
wt.% based on the weight of the automotive gear oil. In some embodiments, the
total sulfur
level can be from about 0.8 to about 4 wt.%, or even about 0.9 to about 3.5
wt.% or about
1 to about 3 wt.%. The sulfur can be provided, for example, from organo-
sulfides, including
polysulfides, such as sulfurized olefins, thiadiazoles and thiadiazole adducts
such as post
treated dispersants.
[0032]
Organo-sulfides can be present in in the automotive gear oil in a range of,
for example, 0 wt.% to 10 wt.%, 0.01 wt.% to 10 wt.%, 0.1 wt.% to 8 wt.%, 0.25
wt.% to
6 wt.%, 2 wt.% to 5 wt.%, or 3 wt.% to 5 wt.%, 3% to 6% of the automotive gear
oil.
[0033]
Examples of a thiadiazole include 2,5-dimercapto-1,3,4-thiadiazole, or oli-
gomers thereof, a hydrocarbyl -substituted 2,5-dimercapto-1,3,4-thiadiazole, a
hydro-
carbylthio-substituted 2,5-dimercapto-1,3,4-thiadiazole, or oligomers thereof.
The oligo-
mers of hydrocarbyl-substituted 2,5-dimercapto-1,3,4-thiadiazole typically
form by form-
ing a sulfur-sulfur bond between 2,5-dimercapto-1,3,4-thiadiazole units to
form oligomers
of two or more of said thiadiazole units. Further examples of thiadiazole
compounds are
found in WO 2008,094759, paragraphs 0088 through 0090.
[0034]
The organosulfide may alternatively be a polysulfide. In one embodiment at
least about 50 wt.% of the polysulfide molecules are a mixture of tri- or
tetra-sulfides. In
other embodiments at least about 55 wt.%, or at least about 60 wt.% of the
polysulfide
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molecules are a mixture of tri- or tetra-sulfides. The polysulfides include
sulfurized organic
polysulfides from oils, fatty acids or ester, olefins or polyolefins.
[0035]
Oils which may be sulfurized include natural or synthetic oils such as
mineral
oils, lard oil, carboxylate esters derived from aliphatic alcohols and fatty
acids or aliphatic
carboxylic acids (e.g., myristyl oleate and oleyl oleate), and synthetic
unsaturated esters or
glycerides.
[0036]
Fatty acids include those that contain 8 to 30, or 12 to 24 carbon atoms.
Ex-
amples of fatty acids include oleic, linoleic, linolenic, and tall oil.
Sulfurized fatty acid
esters prepared from mixed unsaturated fatty acid esters such as are obtained
from animal
fats and vegetable oils, including tall oil, linseed oil, soybean oil,
rapeseed oil, and fish oil.
[0037]
The polysulfide may also be derived from an olefin derived from a wide
range
of alkenes, typically having one or more double bonds. The olefins in one
embodiment
contain 3 to 30 carbon atoms. In other embodiments, olefins contain 3 to 16,
or 3 to 9 carbon
atoms. In one embodiment the sulfurized olefin includes an olefin derived from
propylene,
isobutylene, pentene, or mixtures thereof. Isobutene, propylene and their
dimers, trimers
and tetramers, and mixtures thereof are further olefinic compounds. Of these
compounds,
isobutylene and diisobutylene are particularly desirable because of their
availability and
the particularly high sulfur containing compositions which can be prepared
therefrom. In
one embodiment the polysulfide comprises a polyolefin derived from
polymerizing, by
known techniques, an olefin as described above. In one embodiment the
polysulfide in-
cludes, dibutyl disulfide, dibutyl tetrasulfide, sulfurized methyl ester of
oleic acid, sulfu-
rized alkylphenol, sulfurized dipentene, sulfurized dicyclopentadiene,
sulfurized terpene,
and sulfurized Diels-Alder adducts; phosphosulfurized hydrocarbons.
[0038]
The automotive gear oils can also have a total phosphorus level of about
0.03
to about 0.5 wt.%, or 0.03 to about 0.35 wt.%, or even about 0.05 to about 0.3
wt.%, or about
0.08 to about 0.2 wt.%, or about 0.13 to about 0.2 wt.%, or about 0.1 to about
0.25 wt.%.
The phosphorus can be brought to the automotive gear oil, for example, from
the amine-
containing phosphorus antiwear agents discussed above, or other phosphorus
containing
compounds.
[0039] Other phosphorus-containing compounds may be included along with the
amine-
containing phosphorus antiwear agents. Such other phosphorus containing
compounds can
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include phosphites or phosphonates. Suitable phosphites or phosphonates
include those
having at least one hydrocarbyl group with 3 or 4 or more, or 8 or more, or 12
or more,
carbon atoms. The phosphite may be a mono-hydrocarbyl substituted phosphite, a
di-hy-
drocarbyl substituted phosphite, or a tri-hydrocarbyl substituted phosphite.
The phospho-
5 nate may be a mono-hydrocarbyl substituted phosphonate, a di-hydrocarbyl
substituted
phosphonate, or a tri-hydrocarbyl substituted phosphonate.
[0040] In one embodiment the phosphite is sulphur-free i.e., the
phosphite is not a thi-
ophosphite.
[0041] The phosphite or phosphonate may be represented by the formulae:
RO H XI
ROPµ
0
XII
R-0
10 .. wherein at least one R may be a hydrocarbyl group containing at least 3
carbon atoms and
the other R groups may be hydrogen. In one embodiment, two of the R groups are
hydro-
carbyl groups, and the third is hydrogen. In one embodiment every R group is a
hydrocarbyl
group, i.e., the phosphite is a tri-hydrocarbyl substituted phosphite. The
hydrocarbyl
groups may be alkyl, cycloalkyl, aryl, acyclic or mixtures thereof.
[0042] In the art, a phosphonate (i.e., formula XI with R = hydrocarbyl)
may also be
referred to as a phosphite ester. Where one of the R groups in formula XII is
an H group,
the compound would generally be considered a phosphite, but such a compound
can often
exist in between the tautomers of formula XI and XII, and thus, could also be
referred to as
a phosphonate or phosphite ester. For ease of reference, the term phosphite,
as used herein,
will be considered to encompass both phosphites and phosphonates.
[0043] The R hydrocarbyl groups may be linear or branched, typically
linear, and satu-
rated or unsaturated, typically saturated.
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[0044]
In one embodiment, the other phosphorus-containing compound can be a C3-8
hydrocarbyl phosphite, or mixtures thereof, i.e., wherein each R may
independently be hy-
drogen or a hydrocarbyl group having 3 to 8, or 4 to 6 carbon atoms, typically
4 carbon
atoms. Typically the C3-8 hydrocarbyl phosphite comprises dibutyl phosphite.
The C3-8
hydrocarbyl phosphite may deliver at least 175 ppm, or at least 200 ppm of the
total amount
of phosphorus delivered by the phosphorus-containing compounds. The C3-8
hydrocarbyl
phosphite may deliver at least 25wt.%, 35 wt.%, 45 wt.%, or 50 wt.% to 80
wt.%, or 50
wt.% to 75 wt.% or 60 wt.% to 70 wt.% of the total amount of phosphorus to the
lubricant
composition.
[0045] In one embodiment, the phosphorus-containing compound can be a C12-
22 hydro-
carbyl phosphite, or mixtures thereof, i.e., wherein each R may independently
be hydrogen
or a hydrocarbyl group having 12 to 24, or 14 to 20 carbon atoms, typically 16
to 18 carbon
atoms. Typically the C12-22 hydrocarbyl phosphite comprises a C16-18
hydrocarbyl phos-
phite. Examples of alkyl groups for R3, R4 and R5 include octyl, 2-ethylhexyl,
nonyl, decyl,
undecyl, dodecyl, tridecyl, tetradecyl, pentadecyl, hexadecyl, heptadecyl,
octadecyl, octa-
decenyl, nonadecyl, eicosyl or mixtures thereof. The C12-22 hydrocarbyl
phosphite may be
present in the lubricant composition at about 0.05 wt.% to about 4.0 wt.% of
the lubricant
composition, or from about 0.05 wt.% to about 3 wt.%, or from about 0.05 wt.%
to about
1.5 wt.%, or from about 0.05 wt.% to about 1 wt.%, or from about 0.1 wt.% to
about 0.5
wt.% of the lubricant composition.
[0046]
In some embodiments, the other phosphorus containing compound can include
both a C3-8 and a C12 to C24 hydrocarbyl phosphite.
[0047]
In one embodiment, the phosphite ester comprises the reaction product of
(a) a
monomeric phosphoric acid or an ester thereof with (b) at least two alkylene
diols; a first
alkylene diol (i) having two hydroxy groups in a 1,4 or 1,5 or 1,6
relationship; and a second
alkylene di 01(u) being an alkyl-substitute 1,3-propylene glycol.
[0048]
Sulfur containing phosphites can include, for example, a material
represented
by the formula [R10(0R2)(S)PSC2H4(C)(0)0R40],13(0R5)2(0)H, wherein RI- and R2
are
each independently hydrocarbyl groups of 3 to 12 carbon atoms, or 6 to 8
carbon atoms, or
wherein R1 and R2 together with the adjacent 0 and P atoms form a ring
containing 2 to 6
carbon atoms; R4 is an alkylene group of 2 to 6 carbon atoms or 2 to 4 carbon
atoms; R5 is
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12
hydrogen or a hydrocarbyl group of 1 to about 12 carbon atoms; and n is 1 or
2. The C12-22
hydrocarbyl phosphite may be present in the lubricant composition at about
0.05 wt.% to
about 1.5 wt.% of the lubricant composition, or from about 0.1 wt.% to about
1.0 wt.% of
the lubricant composition.
[0049] In
one embodiment, the other phosphorus containing compound can be a phos-
phorus containing amide. Phosphorus containing amides can be prepared by
reaction of di-
thiophosphoric acid with an unsaturated amide. Examples of unsaturated amides
include
acrylamide, N,N'-methylene bisacrylamide, methacrylamide, crotonamide and the
like. The
reaction product of the phosphorus acid and the unsaturated amide may be
further reacted
with a linking or a coupling compound, such as formaldehyde or
paraformaldehyde. The
phosphorus containing amides are known in the art and are disclosed in U.S.
Pat. Nos.
4,670,169, 4,770,807 and 4,876,374 which are incorporated by reference for
their disclosures
of phosphorus amides and their preparation.
[0050]
Other materials may be present in the automotive gear oil in their
conventional
amounts including, for example, viscosity modifiers, dispersants, pour point
additives, ex-
treme pressure agents, antifoams, copper anticorrosion agents (such as
dimercaptothiadia-
zole compounds), iron anticorrosion agents, friction modifiers, dyes,
fragrances, optional
detergents and antioxidants, and color stabilizers, for example.
[0051]
The disclosed technology provides a method of lubricating an automotive
gear,
comprising supplying thereto an automotive gear oil as described herein, that
is, an
automotive gear oil having a total sulfur level of 0.75 to 5 wt.% and
containing (a) an oil of
lubricating viscosity, (b) an oil-soluble titanium compound, and (c) an amine-
containing
phosphorus antiwear agent, and operating the driveline device.
[0052]
The automotive gear may comprise a gear as in a gearbox of a vehicle (e.g.,
a
manual transmission) or in an axle or differential, or in other driveline
power transmitting
driveline devices. The automotive gear may also include bearings. Lubricated
gears may
include hypoid gears, such as those for example in a rear drive axle.
[0053]
The amount of each chemical component described is presented exclusive of
any solvent or diluent oil, which may be customarily present in the commercial
material, that
is, on an active chemical basis, unless otherwise indicated. However, unless
otherwise
indicated, each chemical or composition referred to herein should be
interpreted as being a
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13
commercial grade material which may contain the isomers, by-products,
derivatives, and
other such materials which are normally understood to be present in the
commercial grade.
[0054]
As used herein, the term "hydrocarbyl substituent" or "hydrocarbyl group"
is
used in its ordinary sense, which is well-known to those skilled in the art.
Specifically, it
refers to a group having a carbon atom directly attached to the remainder of
the molecule and
having predominantly hydrocarbon character. Examples of hydrocarbyl groups
include:
= hydrocarbon substituents, that is, aliphatic (e.g., alkyl or alkenyl),
alicyclic (e.g.,
cycloalkyl, cycloalkenyl) sub stituents, and aromatic-, aliphatic-, and
alicyclic-
substituted aromatic substituents, as well as cyclic substituents wherein the
ring is
completed through another portion of the molecule (e.g., two substituents
together
form a ring);
= substituted hydrocarbon sub stituents, that is, sub stituents containing
non-
hydrocarbon groups which, in the context of this invention, do not alter the
predominantly hydrocarbon nature of the substituent (e.g., halo (especially
chloro
and fluoro), hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and
sulfoxy);
= hetero substituents, that is, substituents which, while having a
predominantly hy-
drocarbon character, in the context of this invention, contain other than
carbon in
a ring or chain otherwise composed of carbon atoms and encompass substituents
as pyridyl, furyl, thienyl and imidazolyl. Heteroatoms include sulfur, oxygen,
and
nitrogen. In general, no more than two, or no more than one, non-hydrocarbon
substituent will be present for every ten carbon atoms in the hydrocarbyl
group;
alternatively, there may be no non-hydrocarbon substituents in the hydrocarbyl
group.
[0055] It is known that some of the materials described herein may interact
in the final
formulation, so that the components of the final formulation may be different
from those that
are initially added. For instance, metal ions (of, e.g., a detergent) can
migrate to other electron
rich sites of other molecules. The products formed thereby, including the
products formed
upon employing the composition of the present invention in its intended use,
may not be
susceptible of easy description. Nevertheless, all such modifications and
reaction products
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are included within the scope of the present invention; the present invention
encompasses the
composition prepared by admixing the components described above.
[0056] The invention herein may be better understood with reference
to the following
examples.
EXAMPLES
[0057] Several Automotive Gear Oils ("AGO") were prepared for
testing according
to the following formulations (numbers represent wt%).
Sample 1 Sample 2 Sample 3 Sample 4 Sample 5
Olefin polymer 22 22 22 22 22
Sulfurized olefin 4.57 4.57 4.57 4.57 4.57
Phosphorus amine salt-1* 1.66 1.66 1.66 1.66 1.66
Substituted thiadiazole 0.15 0.15 0.15 0.15 0.15
Alkyl amide 0.13 0.13 0.13 0.13 0.13
Antifoam 0.1 0.1 0.1 0.1 0.1
Borated dispersant 0.78
Non-borated dispersant 0.75 0.75 0.75 0.75
Oil soluble Ti compound 0.12 0.24 0.37
Oil of lubricating viscosity Sum to 100
*Phosphorus amine salt-1 contains sulfur.
[0058] The gear oil samples were evaluated in the L-60-1 Thermal
Oxidative Stabil-
ity of Gear Lubricants Test (based on ASTM Method D5704), which is a 50 hour
test. SAE
J2360 standard for thermal stability requires the lubricant tested under L-60-
1 to show a
gear sludge rating of 9.4 minimum, gear carbon/varnish rating of 7.5 minimum,
viscosity
increase of 100% maximum, pentane insoluble of 3.0% maximum and toluene
insoluble of
2.0% maximum.
Sample 1 Sample 2 Sample 3 Sample 4 Sample 5
ppm B 247
ppm Ti 106 202 303
L-60-1 Result
Sludge 9.4 9.5 9.5 9.6 9.6
CarbonNarnish 8.8 2.4 4.3 8.2 8.1
Viscosity Increase % 17 13 13 21 23
Pentane insoluble 0.3 0.1 0.1 0.6 0.2
Toluene insoluble 0.2 0 0 0.9 0.2
[0059] The impact of borated dispersant can be observed by comparing
the car-
bon/varnish ratings for Sample 1 vs. Sample 2. Like Sample 2, Samples 3-5 do
not contain
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borated dispersant. However, these samples contain increasing amounts of oil
soluble tita-
nium resulting in improved carbon/varnish ratings.
[0060] Additional gear oil samples were prepared in which the sulfur
containing phos-
phorus amine salt was replaced with a substantially sulfur-free phosphorus
amine salt. Gear
5 oil samples 6-9 were prepared according to the following formulations
(numbers represent
wt%):
Sample 6 Sample 7 Sample 8 Sample 9
Methacrylate copolymer 9 9 9 9
Sulfurized olefin 4.6 4.6 4.6 4.6
Phosphorus amine salt-2* 1.84 1.84 1.84 1.84
Substituted thiadiazole 0.2 0.2 0.2 0.2
Rust inhibitor 0.2 0.2 0.2 0.2
Antifoam 0.04 0.04 0.04 0.04
Borated dispersant 0.78
Non-borated dispersant 0.75 0.75 0.75 0.75
Oil soluble Ti compound 0.3 0.6
Oil of lubricating viscosity Sum to 100
Phosphorus amine salt-2* is substantially sulfur free.
[0061] Gear oil samples 6-9 contain identical concentrations of non-
borated disper-
10 sant. Only Sample 6 contains borated dispersant. Samples 6 and 7 are Ti-
free, and Samples
8 and 9 contain 300 ppm Ti and 600ppm Ti respectively. These four samples were
also tested
in the L-60-1 Thermal Oxidative Stability of Gear Lubricants Test (based on
ASTM Method
D5704). Samples 6 and 7 are comparative samples that were tested to again
demonstrate the
importance of the presence of borated dispersant to achieve the desired
carbon/varnish rating.
15 Boron-free samples 8 and 9 contain oil soluble Ti which improves the
carbon/varnish rating
to achieve the desired thermal oxidative stability in this test.
Sample 6 Sample 7 Sample 8 Sample 9
ppm B 252
ppm Ti 261 516
L-60-1 Result
Sludge 9.5 9.6 9.7 9.5
CarbonNarnish 9.7 6.4 8.7 9
Viscosity Increase % 13 11 20 29
Pentane insoluble 0.6 0.3 0.1 0.1
Toluene insoluble 0 0.4 0.1 0.1
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[0062] Gear oil samples 10-13 were prepared without borated
dispersant according to
the following formulations (numbers represent wt%):
Sample 10 Sample 11 Sample 12 Sample 13
Methacrylate copolymer 9 9 9 9
Sulfurized olefin 4.6 4.6 4.6 4.6
Phosphorus amine salt-3* 1.41 1.41 1.41 1.41
Substituted thiadiazole 0.2 0.2 0.2 0.2
Rust inhibitor 0.2 0.2 0.2 0.2
Antifoam 0.04 0.04 0.04 0.04
Non-borated dispersant 0.75 0.75 0.75 0.75
Oil soluble Ti compound 0 0.3 0.6 0.9
Oil of lubricating viscosity Sum to 100
Phosphorus amine salt-3* is substantially sulfur free and at least 30 mole
percent of the phosphorus
atoms are in an alkyl pyrophosphate structure.
[0063] Gear oil samples 10-13 contain identical concentrations of
non-borated disper-
sant. Sample 10 is Ti-free, and Samples 11, 12 and 13 contain 300 ppm Ti,
600ppm Ti and
900ppm Ti respectively. These four samples were also tested in the L-60-1
Thermal Oxida-
tive Stability of Gear Lubricants Test (based on ASTM Method D5704). Samples
10 was
tested to demonstrate the carbon/varnish performance without the presence of a
borated dis-
persant. Boron-free samples 11, 12 and 13 contain increasing amounts of oil
soluble Ti which
improves the carbon/varnish rating to achieve the desired thermal oxidative
stability in this
test.
Sample 10 Sample 11 Sample 12 Sample 13
ppm B
ppm Ti 319 618 775
L-60-1 Result
Sludge 9.7 9.6 9.7 9.8
CarbonNarnish 2.7 5.7 9.8 10
Viscosity Increase % 11 17 36 39
Pentane insoluble 0.4 0.1 0.9 0.6
Toluene insoluble 0.4 0 0.4 0.1
[0064] Gear oil samples 14 and 15 do not contain borated dispersant. These
samples
contain a mixture of Phosphorus amine-salt-1 and phosphite. Sample 14 is a
comparative
sample without an oil soluble Ti compound, while Sample 15 contains 525ppm Ti.
Sample 14 Sample 15
Methacrylate copolymer 9 9
Sulfurized olefin 4.6 4.6
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Phosphorus amine salt-1* 0.82 0.82
Phosphite 0.725 0.725
Substituted thiadiazole 0.2 0.2
Rust inhibitor 0.2 0.2
Antifoam 0.04 0.04
Non-borated dispersant 0.75 0.75
Oil soluble Ti compound 0 0.6
[0065]
Addition of the oil soluble Ti compound in the absence of boron-containing
compounds results in improved Carbon/Varnish ratings in the L-60-1 test.
Sample 14 Sample 15
ppm B
ppm Ti 525
L-60-1 Result
Sludge 9.6 9.7
CarbonNarnish 4.1 10
Viscosity Increase % 8 15
Pentane insoluble 0.1 0.1
Toluene insoluble 0.2 0
[0066] Each
of the documents referred to above is incorporated herein by reference,
including any prior applications, whether or not specifically listed above,
from which priority
is claimed. The mention of any document is not an admission that such document
qualifies
as prior art or constitutes the general knowledge of the skilled person in any
jurisdiction.
Except in the Examples, or where otherwise explicitly indicated, all numerical
quantities in
this description specifying amounts of materials, reaction conditions,
molecular weights,
number of carbon atoms, and the like, are to be understood as optionally
modified by the
word "about." It is to be understood that the upper and lower amount, range,
and ratio limits
set forth herein may be independently combined. Similarly, the ranges and
amounts for each
element of the invention can be used together with ranges or amounts for any
of the other
elements.
[0067]
As used herein, the transitional term "comprising," which is synonymous
with "including," "containing," or "characterized by," is inclusive or open-
ended and does
not exclude additional, un-recited elements or method steps. However, in each
recitation of
"comprising" herein, it is intended that the term also encompass, as
alternative embodiments,
the phrases "consisting essentially of' and "consisting of" where "consisting
of" excludes
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any element or step not specified and "consisting essentially of" permits the
inclusion of
additional un-recited elements or steps that do not materially affect the
essential or basic and
novel characteristics of the composition or method under consideration. The
expression "con-
sisting of' or "consisting essentially of," when applied to an element of a
claim, is intended to
restrict all species of the type represented by that element, notwithstanding
the presence of
"comprising" elsewhere in the claim.
[0068] While certain representative embodiments and details have
been shown for
the purpose of illustrating the subject invention, it will be apparent to
those skilled in this
art that various changes and modifications can be made therein without
departing from the
scope of the subject invention. In this regard, the scope of the invention is
to be limited
only by the following claims.
[0069] A lubricant composition comprising an oil of lubricating
viscosity, an amine-
containing phosphorus antiwear agent, and an oil-soluble titanium compound,
wherein the
lubricant composition is substantially free (or free) of boron, and wherein
the lubricant com-
prises a total sulfur level of about 0.75 to about 5 wt.%. The lubricant
composition of the
previous sentence, wherein the oil-soluble titanium compound comprises at
least one of tita-
nium (IV) sulfide; titanium (IV) nitrate; titanium (IV) alkoxides; titanium
phenates; tita-
nium carboxylates; titanium phosphates; titanium sulfonates. The lubricant
composition of
any previous sentence, wherein the oil-soluble titanium compound comprises a
titanium (IV)
alkoxide. The lubricant composition of any previous sentence, wherein the
titanium com-
pound comprises surface-modified titanium dioxide nanoparticles. The lubricant
composi-
tion of any previous sentence, where the oil-soluble titanium compound
comprises titanium
(IV) 2-ethylhexoxide. The lubricant composition of any previous sentence,
where the oil-
soluble titanium compound comprises titanium methoxide. The lubricant
composition of
any previous sentence, where the oil-soluble titanium compound comprises
titanium ethox-
ide. The lubricant composition of any previous sentence, where the oil-soluble
titanium
compound comprises titanium propoxide. The lubricant composition of any
previous sen-
tence, where the oil-soluble titanium compound comprises titanium
isopropoxide. The lub-
ricant composition of any previous sentence, where the oil-soluble titanium
compound com-
prises titanium butoxide. The lubricant composition of any previous sentence,
where the
oil-soluble titanium compound comprises titanium (IV)
(triethanolaminato)isopropoxide.
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The lubricant composition of any previous sentence, wherein the lubricant
comprises a total
phosphorus level of about 0.03-0.5 wt.%. The lubricant composition of any
previous sen-
tence wherein the lubricant comprises a total phosphorus level of about 0.05
to about 0.3
wt.%. The lubricant composition of any previous sentence wherein the lubricant
comprises
a total phosphorus level of about 0.1 to about 0.25 wt.%. The lubricant
composition of any
previous sentence, further comprising an antiwear agent other than the amine-
containing
phosphorus antiwear agent. The lubricant composition of any previous sentence
wherein
the lubricant comprises a total sulfur level of about 0.8 to about 4 wt.%. The
lubricant
composition of any previous sentence wherein the lubricant comprises a total
sulfur level of
about 0.9 to about 3.5 wt.%. The lubricant composition of any previous
sentence wherein
the lubricant comprises a total sulfur level of about 1 to about 3 wt.%. The
lubricant com-
position of any previous sentence, wherein the composition comprises greater
than 200 ppm
titanium. The lubricant composition of any previous sentence, wherein the
composition com-
prises greater than 250 ppm titanium. The lubricant composition of any
previous sentence,
wherein the composition comprises greater than 300 ppm titanium. The lubricant
composi-
tion of any previous sentence, wherein the composition comprises greater than
325 ppm tita-
nium. The lubricant composition of any previous sentence, wherein the
composition com-
prises from 200 to 2000 ppm titanium. The lubricant composition of any
previous sentence,
wherein the composition comprises from 200 to 1500 ppm titanium. The lubricant
composi-
tion of any previous sentence, wherein the composition comprises from 250 to
1500 ppm
titanium. The lubricant composition of any previous sentence, wherein the
composition com-
prises from 300 to 1250 ppm titanium. The lubricant composition of any
previous sentence,
wherein the composition comprises from 325 to 1000 ppm titanium. The lubricant
composi-
tion of any previous sentence, wherein the composition comprises from 325 to
900 ppm tita-
nium. The lubricant composition of any previous sentence, wherein the
composition com-
prises from 350 to 1000 ppm titanium. The lubricant composition of any
previous sentence,
wherein the composition comprises from 350 to 900 ppm titanium. The lubricant
composi-
tion of any previous sentence, wherein the amine-containing phosphorus
antiwear agent com-
prises a substantially sulfur-free alkyl phosphate amine salt wherein at least
about 30 mole
percent of the phosphorus atoms are in an alkyl pyrophosphate salt structure
and at least about
80 mole percent of the alkyl groups are secondary alkyl groups of about 3 to
about 12 carbon
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atoms. The lubricant composition of any previous sentence, wherein the amine-
containing
phosphorus antiwear agent comprises an amine salt of a phosphoric acid ester.
The lubricant
composition of any previous sentence, wherein the amine-containing phosphorus
antiwear
agent comprises an amine salt of a dialkyldithiophosphoric acid ester. The
lubricant com-
5 position of any previous sentence, wherein the amine-containing
phosphorus antiwear agent
comprises an amine salt of a dialkylmonothiophosphoric acid ester. The
lubricant compo-
sition of any previous sentence, wherein the amine-containing phosphorus
antiwear agent
comprises an amine salt of a mono-alkyl phosphite. The lubricant composition
of any pre-
vious sentence, wherein the amine-containing phosphorus antiwear agent
comprises an amine
10 salt of a di-alkyl phosphite. The lubricant composition of any previous
sentence, wherein
the amine-containing phosphorus antiwear agent comprises an amine salt of a
phosphate
hydrocarbon ester comprising a reaction product of phosphorus pentoxide with
an alcohol,
followed by a reaction with an amine. The lubricant composition of any
previous sentence,
comprising less than 150 ppm boron. The lubricant composition of any previous
sentence,
15 comprising less than 100 ppm boron. The lubricant composition of any
previous sentence,
comprising less than 50 ppm boron. The lubricant composition of any previous
sentence,
comprising less than 10 ppm boron. The lubricant composition of any previous
sentence,
comprising less than 1 ppm boron. The lubricant composition of any previous
sentence,
wherein the composition is completely free of boron. A method of lubricating a
driveline
20 device, comprising supplying to the driveline device the lubricant
composition of any previ-
ous sentence, and operating the driveline device. The method of the previous
sentence
wherein the driveline device comprises an axle. The foregoing method, wherein
the driveline
device comprises a bearing. The foregoing method, wherein the driveline device
comprises
a gear.
