U.S. patent application number 11/007071 was filed with the patent office on 2006-06-08 for oxidation stable gear oil compositions.
Invention is credited to Chip Hewette.
Application Number | 20060122073 11/007071 |
Document ID | / |
Family ID | 35965932 |
Filed Date | 2006-06-08 |
United States Patent
Application |
20060122073 |
Kind Code |
A1 |
Hewette; Chip |
June 8, 2006 |
Oxidation stable gear oil compositions
Abstract
A gear oil lubricant composition and method of operating a
vehicle with the composition. The composition may include a first
olefinic lubricant having a viscosity ranging from about 80
centistokes to about 150 centistokes at 100.degree. C. and a second
olefinic lubricant having a viscosity ranging from about 2
centistokes to about 15 centistokes at 100.degree. C. A ratio of
the first olefinic lubricant to the second olefinic lubricant may
range from about 2:1 to about 8:1. Additionally, the composition
may include an alkylated naphthalene base oil, a boronated ashless
dispersant, at least one hindered phenol antioxidant, at least one
alkylated diphenylamine antioxidant, and a gear oil additive
package having an active phosphorus content of less than about 700
ppm and an active sulfur content of less than about 3 wt. %. The
gear oil lubricant composition may contain less than about 0.1
percent by weight antioxidant composition based on a total weight
of the lubricant composition.
Inventors: |
Hewette; Chip; (Richmond,
VA) |
Correspondence
Address: |
DENNIS H. RAINEAR
CHIEF PATENT COUNSEL, ETHYL CORPORATION
330 SOUTH FOURTH STREET
RICHMOND
VA
23219
US
|
Family ID: |
35965932 |
Appl. No.: |
11/007071 |
Filed: |
December 8, 2004 |
Current U.S.
Class: |
508/187 |
Current CPC
Class: |
C10N 2030/02 20130101;
C10N 2020/02 20130101; C10M 2205/0285 20130101; C10N 2030/10
20130101; C10N 2030/72 20200501; C10N 2060/12 20130101; C10M
2207/026 20130101; C10N 2030/08 20130101; C10N 2040/04 20130101;
C10M 2203/065 20130101; C10M 2205/0206 20130101; C10M 169/04
20130101; C10N 2030/42 20200501; C10M 2215/28 20130101; C10M
2215/064 20130101; C10N 2060/14 20130101 |
Class at
Publication: |
508/187 |
International
Class: |
C10L 1/30 20060101
C10L001/30 |
Claims
1. A gear oil lubricant composition comprising: a first olefinic
lubricant having a viscosity ranging from about 80 centistokes to
about 150 centistokes at 100.degree. C.; a second olefinic
lubricant having a viscosity ranging from about 2 centistokes to
about 15 centistokes at 100.degree. C., wherein a ratio of the
first olefinic lubricant to the second olefinic lubricant ranges
from about 2:1 to about 8:1; an alkylated naphthalene base oil; a
boronated ashless dispersant; an antioxidant composition comprising
at least one hindered phenol antioxidant and at least one alkylated
diphenylamine antioxidant; and a gear oil additive package having
an active phosphorus content of less than about 700 ppm and an
active sulfur content of less than about 2.5 wt. %, wherein the
gear oil lubricant composition contains less than about 0.1 percent
by weight antioxidant composition based on a total lubricant
composition.
2. The gear oil lubricant composition of claim 1, wherein the gear
oil additive package comprises an extreme pressure agent, an
antiwear agent, a rust inhibitor, a corrosion inhibitor, a
defoamer, and a process oil.
3. The gear oil lubricant composition of claim 1, further
comprising a seal swelling agent.
4. The gear oil lubricant composition of claim 1, wherein the
composition contains from about 100 to about 700 ppm active
nitrogen atoms.
5. The gear oil lubricant composition of claim 1, wherein the
ashless dispersant comprises a hydrocarbyl substituted
succinimide.
6. The gear oil lubricant composition of claim 5, wherein the
ashless dispersant comprises a boronated/phosphorylated ashless
dispersant.
7. The gear oil lubricant composition of claim 1, wherein the first
and second olefinic lubricant comprises oligomers of
alphaolefins.
8. A vehicle axle containing the gear oil lubricant of claim 1.
9. A heavy duty gear oil lubricant composition comprising: a first
olefinic lubricant having a viscosity ranging from about 80
centistokes to about 150 centistokes at 100.degree. C.; a second
olefinic lubricant having a viscosity ranging from about 2
centistokes to about 15 centistokes at 100.degree. C., wherein a
ratio of the first olefinic lubricant to the second olefinic
lubricant ranges from about 2:1 to about 8:1; an alkylated
naphthalene base oil; a boronated ashless dispersant; an
antioxidant composition comprising at least one hindered phenol
antioxidant and at least one alkylated diphenylamine antioxidant;
and a conventional gear oil additive package; wherein the gear oil
lubricant composition has a reactive amine content of less than
about 100 to about 400 ppm based on an active nitrogen content of
the lubricant composition.
10. The gear oil lubricant composition of claim 9, wherein the gear
oil additive package comprises an extreme pressure agent, an
antiwear agent, a rust inhibitor, a corrosion inhibitor, a
defoamer, and a process oil.
11. The gear oil lubricant composition of claim 9, further
comprising a seal swelling agent.
12. The gear oil lubricant composition of claim 9, wherein the
composition has an active sulfur content ranging from about 1 wt. %
to about 3 wt. % and an active phosphorus content ranging from
about 250 to about 700 ppm.
13. The gear oil lubricant composition of claim 9, wherein the
ashless dispersant comprises a hydrocarbyl substituted
succinimide.
14. The gear oil lubricant composition of claim 13, wherein the
ashless dispersant comprises a boronated/phosphorylated ashless
dispersant.
15. The gear oil lubricant composition of claim 9, wherein the
first and second olefinic lubricant comprises oligomers of
alphaolefins.
16. A vehicle axle containing the gear oil lubricant of claim
9.
17. A thermally stable gear oil lubricant composition, comprising:
a first olefinic lubricant having a viscosity ranging from about 80
centistokes to about 150 centistokes at 100.degree. C.; a second
olefinic lubricant having a viscosity ranging from about 2
centistokes to about 15 centistokes at 100.degree. C., wherein a
ratio of the first olefinic lubricant to the second olefinic
lubricant ranges from about 2:1 to about 8:1; an alkylated
naphthalene base oil; a boronated ashless dispersant; an
antioxidant composition comprising at least one hindered phenol
antioxidant and at least one alkylated diphenylamine antioxidant;
and a conventional gear oil additive package; wherein, with respect
to thermal stability, the lubricant composition has a carbon
varnish rating of greater than about 7.4 and a sludge rating of
greater than about 9.3 after an L60-1 oxidative stability test of
about 300 hours.
18. The gear oil lubricant composition of claim 17, wherein the
lubricant composition has a viscosity rise of less than about
100%.
19. The gear oil lubricant composition of claim 17, wherein the
gear oil additive package comprises an extreme pressure agent, an
antiwear agent, a rust inhibitor, a corrosion inhibitor, a
defoamer, and a process oil.
20. The gear oil lubricant composition of claim 17, further
comprising a seal swelling agent.
21. The gear oil lubricant composition of claim 17, wherein the
composition has an active sulfur content ranging from about 1 wt. %
to about 3 wt. % and an active phosphorus content ranging from
about 300 to about 700 ppm.
22. The gear oil lubricant composition of claim 17, wherein the
ashless dispersant comprises a hydrocarbyl substituted
succinimide.
23. The gear oil lubricant composition of claim 22, wherein the
ashless dispersant comprises a boronated/phosphorylated ashless
dispersant.
24. The gear oil lubricant composition of claim 17, wherein the
first and second olefinic lubricant comprises oligomers of
alphaolefins.
25. A vehicle axle containing the gear oil lubricant of claim
17.
26. A method of operating a vehicle containing a drive axle,
comprising providing as a lubricant for the drive axle a
composition containing: a first olefinic lubricant having a
viscosity ranging from about 80 centistokes to about 150
centistokes at 100.degree. C.; a second olefinic lubricant having a
viscosity ranging from about 2 centistokes to about 15 centistokes
at 100.degree. C., wherein a ratio of the first olefinic lubricant
to the second olefinic lubricant ranges from about 2:1 to about
8:1; an alkylated naphthalene base oil; a boronated ashless
dispersant; an antioxidant composition comprising at least one
hindered phenol antioxidant and at least one alkylated
diphenylamine antioxidant; and a conventional gear oil additive
package; wherein the lubricant composition has an oxidation
stability in a 300 hour L60-1 oxidative stability test that
provides a viscosity increase of less than about 100%, a carbon
varnish rating of greater than about 7.4 and a sludge rating of
greater than or equal to 9.3.
27. The method of claim 28 wherein the vehicle is operated in an
environment having a temperature of greater than about 40.degree.
C.
28. The method of claim 28 wherein the vehicle is operated for a
distance of more than about 30,000 kilometers between lubricant
drain intervals.
29. The method of claim 28 wherein the axle is an axle of a heavy
duty truck vehicle.
30. The method of claim 29 wherein the heavy duty truck vehicle can
pull combined loads in excess of 25 metric tons.
Description
FIELD
[0001] The present disclosure relates to gear oil compositions, and
in particular to gear oil compositions for severe duty applications
that exhibit improved oxidation stability for extended periods of
time.
BACKGROUND
[0002] Lubricants are used to reduce wear between moving parts
where there is metal to metal contact and to remove heat from the
parts. In some applications, such as the axles of heavy duty
vehicles, the lubricants may encounter extreme temperatures in an
environment in which they are used. Extreme temperatures and
applied loads may result in increased oxidation of the lubricants
thereby increasing the viscosity of the lubricants above a
desirable level. As the viscosity increases, the lubricity
properties of the lubricants may significantly decrease to the
point of axle failure.
[0003] Accordingly, for severe duty applications where
environmental temperatures may exceed about 40.degree. C. for
extended periods of time and where the vehicle load may exceed 25
metric tons, axle lubricants must be changed more often than
lubricants used in less harsh environments. If the lubricants are
not changed on a more frequent schedule, damage to moving parts
relying on lubrication may occur. Until now, lubricants for heavy
duty applications, such as GL-5 gear oils, must pass an oxidation
stability test according to an ASTM D5704 (L60-1) that is a 50 hour
test. However, such evaluation does not provide lubricants that are
suitable for the severe duties described above. Accordingly, what
is needed is a lubricant for heavy duty applications that can pass
an L60-1 oxidation stability test of about 300 hours in order to
provide lubricant replacement intervals of significantly greater
than about 30,000 kilometers in a severe environment.
SUMMARY OF THE EMBODIMENTS
[0004] With regard to the foregoing, the disclosure provides a gear
oil lubricant composition including a first olefinic lubricant
having a viscosity ranging from about 80 centistokes to about 150
centistokes at 100.degree. C. and a second olefinic lubricant
having a viscosity ranging from about 2 centistokes to about 15
centistokes at 100.degree. C. A ratio of the first olefinic
lubricant to the second olefinic lubricant ranges from about 2:1 to
about 8:1. Additionally, the composition may include an alkylated
naphthalene base oil, a boronated ashless dispersant, at least one
hindered phenol antioxidant, at least one alkylated diphenylamine
antioxidant, and a gear oil additive package having an active
phosphorus content of less than about 700 ppm and an active sulfur
content of less than about 2 weight percent. The gear oil lubricant
composition may contain less than about 0.1 percent by weight
antioxidant composition based on a total weight of the lubricant
composition.
[0005] In another embodiment there is provided a thermally stable
gear oil lubricant composition. The lubricant composition includes
a first olefinic lubricant having a viscosity ranging from about 80
centistokes to about 150 centistokes at 100.degree. C., and a
second olefinic lubricant having a viscosity ranging from about 2
centistokes to about 15 centistokes at 100.degree. C. A ratio of
the first polyolefinic lubricant to the second olefinic lubricant
ranges from about 2:1 to about 8:1. Also included in the
composition may be an alkylated naphthalene base oil, a boronated
ashless dispersant, an antioxidant composition comprising at least
one hindered phenol antioxidant and at least one alkylated
diphenylamine antioxidant; and a conventional gear oil additive
package. With respect thermal stability, the lubricant composition
may have a carbon varnish rating of greater than about 7.5 and a
sludge rating of about 9.4 after an L60-1 oxidative stability test
of 300 hours.
[0006] In yet another embodiment there is provided a method of
operating a vehicle containing a drive axle. The method includes
providing as a lubricant for the drive axle a composition
containing a first olefinic lubricant having a viscosity ranging
from about 80 centistokes to about 150 centistokes at 100.degree.
C. and a second olefinic lubricant having a viscosity ranging from
about 2 centistokes to about 15 centistokes at 100.degree. C. A
ratio of the first olefinic lubricant to the second olefinic
lubricant ranges from about 2:1 to about 8:1. The composition may
also include an alkylated naphthalene base oil, a boronated ashless
dispersant, an antioxidant composition comprising at least one
hindered phenol antioxidant and at least one alkylated
diphenylamine antioxidant, and a conventional gear oil additive
package. The lubricant composition may have an oxidation stability
in a 300 hour oxidation stability test that provides a viscosity
increase of less than about 100%, a carbon varnish rating of
greater than about 7.4, and a sludge rating of greater than or
equal to about 9.3.
[0007] An advantage of compositions according to the disclosure is
that heavy duty gear applications using the lubricants exhibit
reduce wear and/or failure without decreasing the lubricant
replacement interval. Another advantage is that the lubricant
compositions according to the disclosure may be formulated from
commercially available components. The following detailed
description of embodiments may provide other advantages.
DETAILED DESCRIPTION OF EMBODIMENTS
[0008] 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
a molecule and having a predominantly hydrocarbon character.
Examples of hydrocarbyl groups include:
[0009] (1) hydrocarbon substituents, that is, aliphatic (e.g.,
alkyl or alkenyl), alicyclic (e.g., cycloalkyl, cycloalkenyl)
substituents, 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 an alicyclic radical);
[0010] (2) substituted hydrocarbon substituents, that is,
substituents containing non-hydrocarbon groups which, in the
context of the description herein, do not alter the predominantly
hydrocarbon substituent (e.g., halo (especially chloro and fluoro),
hydroxy, alkoxy, mercapto, alkylmercapto, nitro, nitroso, and
sulfoxy);
[0011] (3) hetero-substituents, that is, substituents which, while
having a predominantly hydrocarbon character, in the context of
this description, contain other than carbon in a ring or chain
otherwise composed of carbon atoms. Hetero-atoms include sulfur,
oxygen, nitrogen, and encompass substituents such as pyridyl,
furyl, thienyl, and imidazolyl. In general, no more than two, such
as no more than one, non-hydrocarbon substituent will be present
for every ten carbon atoms in the hydrocarbyl group; typically,
there will be one non-hydrocarbon substituent in the hydrocarbyl
group.
[0012] Lubricant compositions according to the disclosure contain a
base oil component, an antioxidant composition, an ashless
dispersant, and a gear oil additive package. The compositions may
be characterized by having an active sulfur content of from about 1
wt. % to about 3 wt. %, an active phosphorus content of from about
200 to about 700 ppm, and an active nitrogen content of from about
100 to about 700 ppm, typically from about 300 to about 500 ppm.
The lubricant composition may also be characterized by having a
carbon varnish rating of greater than about 7.4 and a sludge rating
of greater than about 9.3 after a 300 hour oxidation stability test
conducted according to ASTM D5704 (L60-1).
Base Oil Component
[0013] The base oil component of lubricant compositions according
to the disclosure may include an .alpha.-olefin component and a
Group V base oil component. Oligomerized .alpha.-olefins have been
known for many years to be effective synthetic lubricating oils.
For example, U.S. Pat. No. 3,149,178 to Hamilton et al., describes
oligomers of C.sub.6-12 .alpha.-olefins made using a Friedel-Crafts
catalyst, a peroxide catalyst or thermal treatment. The starting
olefins are predominantly .alpha.-olefins, that is, linear terminal
olefins. By predominantly is meant that they contain over about 50
mole percent, as a further example, over about 75 mole percent of
.alpha.-olefins.
[0014] It is desirable to use pure .alpha.-olefins in the base oil
component, but commercially available .alpha.-olefins contain minor
amounts of internal olefins and vinylidene olefins. It has been
found that in making dimmers, fairly large amounts of internal
olefins can be tolerated without adversely affecting the physical
properties of the oligomer. It would appear that either the
.alpha.-olefins in the commercial olefins can react with the
internal olefins or that the internal olefins are in equilibrium
with .alpha.-olefins and that as the .alpha.-olefins react, more
internal olefins are isomerized to .alpha.-olefins.
[0015] Suitable olefinic oligomers for use as a base oil include
hydrogenated olefin oligomers consisting mainly of dimers of
C.sub.6-20 predominantly .alpha.-olefins having a viscosity above
about 3.0 centistokes (cSt) at 100.degree. C. Such oligomers may be
made by contacting a C.sub.6-20 predominantly .alpha.-olefin or
mixture thereof with a Friedel-Crafts catalyst at a temperature of
about 20.degree. C. to about 200.degree. C. until the reaction
mixture excluding monomer is predominantly dimer. Representative
Friedel-Crafts catalysts are BF.sub.3, BCl.sub.3, AlCl.sub.3,
AlBr.sub.3, SnCl4, GaCl.sub.3, and the like. The product is
distilled to remove unreacted monomer and then is hydrogenated.
[0016] Accordingly, olefins which may be used for making the
oligomers are dodecene, tridecene, tetradecene, pentadecene,
hexadecene, heptadecene, and octadecene. When dodecene is used it
should be in a mixture of olefins containing higher olefins, e.g.
tetradecene, hexadecane, and the like. Other suitable olefins used
as starting materials contain about 12 to about 16 carbon atoms and
mixtures thereof with the above stated proviso regarding
dodecene.
[0017] A relatively low viscosity .alpha.-olefin oligomer and a
relatively high viscosity .alpha.-olefin oligomer make up a
predominant amount of the base oil component. By predominant amount
is meant that the base oil contains over 50 percent by weight of
the low and high viscosity .alpha.-olefin oligomers. The
.alpha.-olefin oligomer having the highest viscosity has a
kinematic viscosity at 100.degree. C. of about 80 to about 120 cSt.
The relatively low viscosity .alpha.-olefin oligomer has a
kinematic viscosity at 100.degree. C. of about 6 to about 10 cSt. A
weight ratio of the high viscosity .alpha.-olefin oligomer to the
low viscosity .alpha.-olefin oligomer in the lubricant composition
typically ranges from about 2:1 to about 6:1.
[0018] An important component of lubricant compositions according
to the disclosure is a Group V base oil as specified in the
American Petroleum Institute (API) Base Oil Interchangeability
Guidelines. A suitable Group V component is an alkylated aromatic
compound. Suitable alkylated aromatic compounds include alkylated
benzenes, alkylated anthracenes, alkylated phenanthrenes, alkylated
biphenyls, and alkylated naphthalenes and the like.
[0019] Alkylated naphthalenes may be produced by any suitable means
known in the art, from naphthalene itself or from substituted
naphthalenes which may contain one or more short chain alkyl groups
having up to about eight carbon atoms, such as methyl, ethyl, or
propyl, etc. Suitable alkyl-substituted naphthalenes include
alpha-methylnaphthalene, dimethylnaphthalene, and ethylnaphthalene.
Naphthalene itself is suitable since the resulting mono-alkylated
products have better thermal and oxidative stability than the more
highly alkylated materials. Alkylated naphthalene lubricant
compositions are described in U.S. Pat. No. 3,812,036 to Romine and
U.S. Pat. No. 5,602,086 to Le et al. The production of
alkylnaphthalenes is disclosed in U.S. Pat. No. 4,714,794 to
Yoshida et al. A commercially available alkylated naphthalene is
available from Exxon/Mobil Chemical Company of Houston, Tex. under
the trade name SYNESSTIC.RTM. 12.
[0020] The amount of alkylated naphthalene component in the
lubricant composition may range from about 20 to about 35 percent
by weight of the total weight of the composition. With respect to
the .alpha.-olefin oligomer components, the alkylated naphthalene
component is present in a ratio of .alpha.-olefin oligomers to
alkylated naphthalene ranging from about 1.5:1 to about 2.5:1.
Antioxidant Component
[0021] The antioxidant component of the lubricant compositions
includes at least two antioxidant compounds, i.e., a hindered
phenol antioxidant and an aromatic amine antioxidant. Illustrative
examples of sterically hindered phenolic antioxidants include
orthoalkylated phenolic compounds such as 2,6-di-tert-butylphenol,
4-methyl-2,6-di-tert-butylphenol, 2,4,6-tri-tert-butylphenol,
2-tert-butylphenol, 2,6-diisopropylphenol,
2-methyl-6-tert-butylphenol, 2,4-dimethyl-6-tert-butylphenol,
4-(N,N-dimethylamino-methyl)-2,8-di-tert-butylphenol,
4-ethyl-2,6-di-tert-butylphenol, 2-methyl-6-styryl-phenol,
2,6-distyryl-4-nonylphenol, and their analogs and homologs.
Mixtures of two or more of the foregoing phenolic compounds are
also be used as the first antioxidant compound.
[0022] Aromatic amine antioxidant compounds include aromatic
secondary monoamines and aromatic secondary polyamines.
Illustrative aromatic secondary monoamines include diphenylamine,
alkyl diphenylamines containing 1 or 2 alkyl substituents each
having up to about 16 carbon atoms, phenyl-t-naphthylamine,
phenyl-.beta.-naphthylamine, alkyl- or aralkylsubstituted
phenyl-.beta.-naphthylamine containing one or two alkyl or aralkyl
groups each having up to about 16 carbon atoms, alkyl- or
aralkylsubstituted phenyl-.beta.-naphthylamine containing one or
two alkyl or aralkyl groups each having up to about 16 carbon
atoms, and similar compounds.
[0023] A suitable type of aromatic amine antioxidant is an
alkylated diphenylamine of the general formula
R.sup.1--C.sub.6--H.sub.4--NH--C.sub.6--H.sub.4--R.sup.2 wherein
R.sup.1 is an alkyl group (for example, a branched alkyl group)
having about 8 to about 12 carbon atoms (as another example, about
8 or about 9 carbon atoms) and R.sup.2 is a hydrogen atom,
alkylaryl or an alkyl group (such as a branched alkyl group) having
about 8 to about 12 carbon atoms, (as another example, about 8 or
about 9 carbon atoms). Suitable compounds are available
commercially from Crompton Corporation of Middlebury, Conn. under
the trade names NAUGALUBE.RTM. 438L, 640, and 680. Other
commercially available aromatic amine antioxidants include
compounds available from R. T. Vanderbilt Company, Inc. of Norwalk,
Conn. under the trade names VANLUBE.RTM. SL, DND, NA, 81, 961, and
2005.
[0024] The amount of antioxidant component in lubricant
compositions described herein may be less than about 0.5 percent by
weight of the total weight of lubricant composition. Typically, the
antioxidant component may range from about 0.05 to about 0.25
weight percent based on the total weight of the lubricant
composition. Of the total amount of antioxidant component, the
hindered phenolic antioxidant may be present in an amount that
ranges from about 0.70 to about 1.30 times the amount of aromatic
amine antioxidant in the lubricant composition. A suitable
antioxidant may contain about 50 wt. % hindered phenolic
antioxidant and 50 wt. % aromatic amine antioxidant.
Ashless Dispersant component
[0025] The ashless dispersant of the lubricant compositions
described herein may be selected from any of the ashless
dispersants known to those skilled in the art. A suitable ashless
dispersant is a hydrocarbyl-substituted succinimide dispersant
which is post-treated to provide a boronated or
boronated/phosphorylated dispersant.
[0026] Hydrocarbyl-substituted succinic acylating agents are used
to make hydrocarbyl-substituted succinimides. The
hydrocarbyl-substituted succinic acylating agents include, but are
not limited to, hydrocarbyl-substituted succinic acids,
hydrocarbyl-substituted succinic anhydrides, the
hydrocarbyl-substituted succinic acid halides (especially the acid
fluorides and acid chlorides), and the esters of the
hydrocarbyl-substituted succinic acids and lower alcohols (e.g.,
those containing up to about 7 carbon atoms), that is,
hydrocarbyl-substituted compounds which can function as carboxylic
acylating agents.
[0027] Hydrocarbyl substituted acylating agents are made as by
reacting a polyolefin or chlorinated polyolefin of appropriate
molecular weight with maleic anhydride. Similar carboxylic
reactants can be used to make the acylating agents. Such reactants
may include, but are not limited to, maleic acid, fumaric acid,
malic acid, tartaric acid, itaconic acid, itaconic anhydride,
citraconic acid, citraconic anhydride, mesaconic acid, ethylmaleic
anhydride, dimethylmaleic anhydride, ethylmaleic acid,
dimethylmaleic acid, hexylmaleic acid, and the like, including the
corresponding acid halides and lower aliphatic esters.
[0028] Hydrocarbyl-substituted succinic anhydrides are
conventionally prepared by heating a mixture of maleic anhydride
and an aliphatic olefin at a temperature of from about 175.degree.
C. to about 275.degree. C. The molecular weight of the olefin can
vary depending upon the intended use of the substituted succinic
anhydrides. Typically, the substituted succinic anhydrides will
have a hydrocarbyl group of from about 8-500 carbon atoms. However,
substituted succinic anhydrides used to make lubricating oil
dispersants will typically have a hydrocarbyl group of about 40-500
carbon atoms. Dispersants having a hydrocarbyl group containing
from about 8 to about 150 carbon atoms are referred to herein as
"relatively low molecular weight dispersants." Whereas dispersants
having a hydrocarbyl group containing more than about 150 carbon
atoms up to about 500 carbon atoms are referred to herein as
"relatively high molecular weight dispersants." With the very high
molecular weight substituted succinic anhydrides, it is more
accurate to refer to number average molecular weight (Mn) since the
olefins used to make these substituted succinic anhydrides may
include a mixture of different molecular weight components
resulting from the polymerization of low molecular weight olefin
monomers such as ethylene, propylene and isobutylene.
[0029] The mole ratio of maleic anhydride to olefin can vary
widely. It may vary, for example, from about 5:1 to about 1:5, as
another example, from about 1:1 to about 3:1. With olefins such as
polyisobutylene having a number average molecular weight of about
500 to about 7000, as a further example about 800 to about 3000 or
higher and the ethylene-alpha-olefin copolymers, the maleic
anhydride may be used in stoichiometric excess, e.g. about 1.1 to
about 3 moles maleic anhydride per mole of olefin. The unreacted
maleic anhydride can be vaporized from the resultant reaction
mixture.
[0030] The hydrocarbyl-substituted succinic anhydrides include
polyalkyl or polyalkenyl succinic anhydrides prepared by the
reaction of maleic anhydride with the desired polyolefin or
chlorinated polyolefin, under reaction conditions well known in the
art. For example, such succinic anhydrides may be prepared by the
thermal reaction of a polyolefin and maleic anhydride, as described
in U.S. Pat. Nos. 3,361,673; 3,676,089; and 5,454,964.
Alternatively, the substituted succinic anhydrides can be prepared
by the reaction of chlorinated polyolefins with maleic anhydride,
as described, for example, in U.S. Pat. No. 3,172,892. A further
discussion of hydrocarbyl-substituted succinic anhydrides can be
found, for example, in U.S. Pat. Nos. 4,234,435; 5,620,486 and
5,393,309. Typically, these hydrocarbyl-substituents will contain
from about 40 to about 500 carbon atoms.
[0031] Polyalkenyl succinic anhydrides may be converted to
polyalkyl succinic anhydrides by using conventional reducing
conditions such as catalytic hydrogenation. For catalytic
hydrogenation, a suitable catalyst is palladium on carbon.
Likewise, polyalkenyl succinimides may be converted to polyalkyl
succinimides using similar reducing conditions.
[0032] The polyalkyl or polyalkenyl substituent on the succinic
anhydrides employed herein is generally derived from polyolefins
which are polymers or copolymers of mono-olefins, particularly
1-mono-olefins, such as ethylene, propylene, and butylene. For
example, the mono-olefin employed will have about 2 to about 24
carbon atoms, and as a further example, about 3 to about 12 carbon
atoms. Suitable mono-olefins include propylene, butylene,
particularly isobutylene, 1-octene, and 1-decene. Polyolefins
prepared from such mono-olefins include polypropylene, polybutene,
polyisobutene, and the polyalphaolefins produced from 1-octene and
1-decene.
[0033] In some embodiments, the ashless dispersant may include one
or more alkenyl succinimides of an amine having at least one
primary amino group capable of forming an imide group. The alkenyl
succinimides may be formed by conventional methods such as by
heating an alkenyl succinic anhydride, acid, acid-ester, acid
halide, or lower alkyl ester with an amine containing at least one
primary amino group. The alkenyl succinic anhydride may be made
readily by heating a mixture of polyolefin and maleic anhydride to
about 180.degree. C. to about 220.degree. C. The polyolefin may be
a polymer or copolymer of a lower monoolefin such as ethylene,
propylene, isobutene, and the like, having a number average
molecular weight in the range of about 900 to about 3000 as
determined by gel permeation chromatography (GPC).
[0034] Amines which may be employed in forming the ashless
dispersant include any that have at least one primary amino group
which can react to form an imide group and at least one additional
primary or secondary amino group and/or at least one hydroxyl
group. A few representative examples are: N-methyl-propanediamine,
N-dodecylpropanediamine, N-aminopropyl-piperazine, ethanolamine,
N-ethanol-ethylenediamine, and the like.
[0035] Boronated dispersants may be formed by boronating (borating)
an ashless dispersant having basic nitrogen in the molecule. The
boronated dispersant may contain at least one polyalkylene moiety.
As a further example, the boronated dispersant may include at least
two polyalkylene moieties. The polyalkylene moiety may have a
molecular weight of from about 900 weight average molecular weight
to about 3000 weight average molecular weight. The polyalkylene
moiety, for example, may have a molecular weight of from about 1300
weight average molecular weight to about 2100 weight average
molecular weight. As a further example, the polyalkylene moiety may
have a molecular weight of about 2100 weight average molecular
weight. The polyalkylene moiety may include a polybutenyl group.
Methods that can be used for boronating the various types of
ashless dispersants described above are described for example in
U.S. Pat. Nos. 3,087,936; 3,254,025; 3,281,428; 3,282,955;
2,284,409; 2,284,410; 3,338,832; 3,344,069; 3,533,945; 3,658,836;
3,703,536; 3,718,663; 4,455,243; and 4,652,387.
[0036] The boronated dispersant may include a high molecular weight
dispersant treated with boron such that the borated dispersant
includes up to about 1 wt. % of boron. As another example the
boronated dispersant may include from about 0.7 wt %/o or less of
boron. As a further example, the borated dispersant may include
from about 0.1 to about 0.7 wt % of boron. As an even further
example, the boronated dispersant may include from about 0.25 to
about 0.7 wt % of boron. As a further example, the boronated
dispersant may include from about 0.35 to about 0.7 wt % of boron.
The dispersant may be dissolved in oil of suitable viscosity for
ease of handling. It should be understood that the weight
percentages given here are for neat dispersant, without any diluent
oil added.
[0037] The boronated dispersant may be further reacted with an
organic acid, an anhydride, and/or an aldehyde/phenol mixture. Such
a process may enhance compatibility with elastomer seals, for
example. The boronated dispersant may further include a mixture of
boronated dispersants. As a further example, the boronated
dispersant may include a nitrogen-containing dispersant and/or may
be free of phosphorus.
[0038] The boronated dispersant may be present in the lubricant
composition in an amount of about 1 wt. % to about 5 wt. %.
Further, the fluid may include from about 1.25 wt % to about 3 wt %
of the borated dispersant. Further, the fluid may include from
about 1.5 wt % to about 2.5 wt % of the boronated dispersant.
Further, the lubricant composition may include an amount of the
boronated dispersant sufficient to provide up to 250 parts per
million (ppm) by weight of boron in the finished composition, such
as for example, from about 50 to about 250 ppm by weight of boron
in the finished composition.
[0039] Phosphorylated dispersants may be formed by treating an
ashless dispersant with an inorganic phosphorus acid or anhydride.
Useful phosphorus acids or anhydrides which may be useful in
forming the post-treated ashless dispersant include phosphorous
acid (H.sub.3PO.sub.3), phosphoric acid, hypophosphoric acid,
phosphorus trioxide (P.sub.2O.sub.3), phosphorus tetraoxide
(P.sub.2O.sub.4), and phosphoric anhydride (P.sub.2O.sub.5).
Mixtures of two or more such compounds can be used. Illustrative
examples of dihydrocarbyl hydrogen phosphites which may be reacted
with the basic nitrogen-containing dispersants for the purposes of
this invention, include diethyl hydrogen phosphite, dibutyl
hydrogen phosphite, di-2-ethylhexyl hydrogen phosphite, didecyl
hydrogen phosphite, dicyclohexyl hydrogen phosphite, diphenyl
hydrogen phosphite, isopropyl octyl hydrogen phosphite,
ditetradecyl hydrogen phosphite, dibenzyl hydrogen phosphite, and
the like. Normally the hydrocarbyl groups will each contain up to
about 30 carbon atoms. Mixtures of two or more such phosphites can
be employed. Dibutyl hydrogen phosphite is a suitable dihydrocarbyl
phosphite. Among the monohydrocarbyl-phosphites which can be
utilized in the practice of this invention include such compounds
as monomethyl phosphite, monoethyl phosphite, monobutyl phosphite,
monohexyl phosphite, monocresyl phosphite, monobenzyl phosphite,
monoallyl phosphite, and the like, and mixtures of two or more such
compounds. The hydrocarbyl group will normally contain up to about
30 carbon atoms. Mixtures of monohydrocarbyl and dihydrocarbyl
phosphites are also suitable, as are the trihydrocarbyl phosphites
and the sulfur analogs of the foregoing phosphites. Phosphorylated
ashless dispersants are described for example in U.S. Pat. No.
5,171,466.
[0040] The ashless dispersant component may also be glycolated by
reacting a succinimide with glycolic acid as described in U.S. Pat.
No. 5,235,067.
[0041] A particularly suitable ashless dispersant is available from
Afton Chemical Corporation of Richmond, Va. under the trade name
HiTEC.RTM. 637.
Gear Oil Additive Package Component
[0042] Another component of the gear oil lubricant composition
according to the disclosure is a gear oil additive package. The
gear additive package typically contains one or more of the
following additives: corrosion inhibitors, extreme pressure
additives, anti-wear additives, rust inhibitors, defoamers, and a
process oil. The gear additive package may be, although it does not
have to be, a fully-formulated gear additive package, such as a
package meeting the requirements for API GL-5 and/or API MT-1
and/or MIL-PRF-2105E and/or AGMA 9005-D94. The type and amount of
the components present in the gear additive package will depend on
the intended final use of the product. The gear additive package is
typically present in an amount of from about 2 to about 25 weight
percent, based on the total weight of the lubricant
composition.
[0043] A suitable gear oil additive package is available from Afton
Chemical Corporation under the trade name HiTEC.RTM. 340.
Extreme Pressure Agent
[0044] Various types of sulfur-containing extreme pressure agents
may be used in the gear oil additive package. Examples include
dihydrocarbyl polysulfides; sulfurized olefins; sulfurized fatty
acid esters of both natural and synthetic origins; trithiones;
sulfurized thienyl derivatives; sulfurized terpenes; sulfurized
oligomers of C.sub.2-C.sub.8 monoolefins; and sulfurized
Diels-Alder adducts such as those disclosed in U.S. reissue patent
Re 27,331. Specific examples include sulfurized polyisobutene,
sulfurized isobutylene, sulfurized diisobutylene, sulfurized
triisobutylene, dicyclohexyl polysulfide, diphenyl polysulfide,
dibenzyl polysulfide, dinonyl polysulfide, and mixtures of
di-tert-butyl polysulfide such as mixtures of di-tert-butyl
trisulfide, di-tert-butyl tetrasulfide and di-tert-butyl
pentasulfide, among others. Combinations of such categories of
sulfur-containing extreme pressure agents can also be used, such as
a combination of sulfurized isobutylene and di-tert-butyl
trisulfide, a combination of sulfurized isobutylene and dinonyl
trisulfide, a combination of sulfurized tall oil and dibenzyl
polysulfide. The amount of extreme pressure agent in the gear oil
additive package may range from about 75 to about 95 percent by
weight of the total weight of the additive package. In terms of
active sulfur content in the lubricant compositions, the lubricant
composition may contain from about 1 wt. % to about 3 wt. % active
sulfur.
Antiwear Agents
[0045] The antiwear agents may be phosphorus-containing antiwear
agents which may include an organic ester of phosphoric acid,
phosphorous acid, or an amine salt thereof. For example, the
phosphorus-containing antiwear agent may include one or more of a
dihydrocarbyl phosphite, a trihydrocarbyl phosphite, a
dihydrocarbyl phosphate, a trihydrocarbyl phosphate, any sulfur
analogs thereof, and any amine salts thereof. As a further example,
the phosphorus-containing antiwear agent may include at least one
of dibutyl hydrogen phosphite (such as HiTEC.RTM. 528 antiwear
agent available from Afton Chemical Corporation of Richmond, Va.)
and an amine salt of sulfurized dibutyl hydrogen phosphite (such as
HiTEC.RTM. 833 antiwear agent available from Afton Chemical
Corporation).
[0046] The phosphorus-containing antiwear agent may be present in
an amount sufficient to provide about 200 to about 700 parts per
million by weight of phosphorus in the lubricant composition. As a
further example, the phosphorus-containing antiwear agent may be
present in an amount sufficient to provide about 150 to about 450
parts per million by weight of phosphorus in the lubricant
composition.
[0047] The gear oil additive package component may include from
about 1 wt % to about 10 wt % of the phosphorus-containing antiwear
agent. As a further example, the gear oil additive package
component may include from about 3 wt % to about 8 wt % of the
phosphorus-containing antiwear agent. As an example, the gear oil
additive package may include from about 4.5 wt % to about 5.5 wt %
of an amyl acid phosphate.
Corrosion inhibitors
[0048] Copper corrosion inhibitors used in the gear oil additive
package may include thiazoles, triazoles, and thiadiazoles.
Examples include benzotriazole, tolytriazole, octyltriazole,
decyltriazole, dodecyltriazole, 2-mercaptobenzothiazole,
2,5-dimercapto-1,3,4-thiadiazole,
2-mercapto-5-hydrocarbylthio-1,3,4-thiadiazoles,
2-mercapto-5-hydrocarbyldithio-1,3,4-thiadiazoles,
2,5-bis(hydrocarbylthio)-1,3,4-thiadiazoles, and
2,5-bis-(hydrocarbyldithio)-1,3,4-thiadiazoles. Suitable compounds
include the 1,3,4-thiadiazoles, especially the
2-hydrocarbyldithio-5-mercapto-1,3,4-dithiadiazoles and the
2,5-bis(hydrocarbyldithio)-1,3,4-thiadiazoles, a number of which
are available as articles of commerce. Other suitable inhibitors of
copper corrosion include ether amines; polyethoxylated compounds
such as ethoxylated amines, ethoxylated phenols, and ethoxylated
alcohols; imidazolines; and the like. See, for example, U.S. Pat.
Nos. 3,663,561 and 4,097,387. Concentrations of up to about 5 wt. %
in the gear oil additive package component are typical. Suitable
copper corrosion inhibitors include ashless dialkyl thiadiazoles.
One example of a commercially available ashless dialkyl thiadiazole
is HiTEC.RTM. 4313 corrosion inhibitor, available from Afton
Chemical Corporation.
Rust Inhibitors
[0049] Rust inhibitors are another inhibitor additive typically
included in the gear oil additive package. Such materials include
monocarboxylic acids and polycarboxylic acids. Examples of suitable
monocarboxylic acids are octanoic acid, decanoic acid and
dodecanoic acid. Suitable polycarboxylic acids include dimer and
trimer acids such as are produced from such acids as tall oil fatty
acids, oleic acid, linoleic acid, or the like. Products of this
type are currently available from various commercial sources, such
as, for example, the dimer and trimer acids sold under the HYSTRENE
trademark by the Humko Chemical Division of Witco Chemical
Corporation and under the EMPOL trademark by Henkel
Corporation.
[0050] Another useful type of rust inhibitor which may be used is
comprised of the alkenyl succinic acid and alkenyl succinic
anhydride corrosion inhibitors such as, for example,
tetrapropenylsuccinic acid, tetrapropenylsuccinic anhydride,
tetradecenylsuccinic acid, tetradecenylsuccinic anhydride,
hexadecenylsuccinic acid, hexadecenylsuccinic anhydride, and the
like. Also useful are the half esters of alkenyl succinic acids
having about 8 to about 24 carbon atoms in the alkenyl group with
alcohols such as the polyglycols.
[0051] Still other suitable rust inhibitors include ether amines;
acid phosphates; amines; polyethoxylated compounds such as
ethoxylated amines, ethoxylated phenols, and ethoxylated alcohols;
imidazolines; aminosuccinic acids or derivatives thereof, and the
like. Materials of these types are available as articles of
commerce. Mixtures of such rust inhibitors may be used. The amount
of rust inhibitor in the gear oil additive package component may
range from about 2 to about 8 weight percent based on the total
weight of the gear oil additive package.
Antifoam agents
[0052] A foam inhibitor forms another component of the gear oil
additive package. Foam inhibitors may be selected from silicones,
polyacrylates, surfactants, and the like. One suitable acrylic
defoamer material is PC-2244 available from Monsanto Company. The
amount of antifoam agent in the gear oil additive package may range
from about 0.5 to about 2.0 weight percent based on the total
weight of the gear oil additive package.
Process Oil
[0053] The process oil used in the gear oil additive package may be
a natural oil, a mineral oil, or a blend of such oils. The oil can
be paraffinic, naphthenic, or a blend of mineral oils. Pursuant to
an embodiment, the process oil is a 60 Neutral mineral oil. The
process oil is present in the gear oil additive package in an
amount sufficient to solubilize the components of the additive
package. Typically, the additive package will contain from about 2
to about 10 percent by weight of the process oil.
[0054] The following non-limiting example is given to illustrate
aspects of the disclosed embodiments. The example is not intended
to limit the embodiments as disclosed herein.
EXAMPLE
[0055] A gear oil lubricant (Sample 1) was formulated as follows:
TABLE-US-00001 Component Weight Percent 8 cSt polyalphaolefin base
oil 11.59 100 cSt polyalphaolefin base oil 47.00 alkylated
naphthalene base oil 28.00 seal swell agent 8.00 gear oil additive
package 4.00 boronated ashless dispersant 1.31 hindered phenol
antioxidant 0.03 alkylated diphenylamine antioxidant 0.03 Process
oil 0.04
[0056] The above gear oil formulation had a viscosity grade of
80W-140, and was tested 300 hours for thermal and oxidative
stability according to the ASTM D 5704 (L-60-1) using the SAE J2360
procedure. The results are given in the following table.
TABLE-US-00002 SAE J2360 Sample 1 Oxidation Stability Test (L-60-1)
50 hours 300 hours Viscosity Rise (%) 100 Max. 89.24 Pentane
Insolubles (wt. %) 3.0 Max. -0.86 Toluene Insolubles (wt. %) 2.0
Max. 0.06 Carbon Varnish (Rating) 7.5 Min. 8.30 Sludge (Rating) 9.4
Min. 9.47
[0057] From the foregoing table, it is evident that a gear oil
lubricant according to the disclosed embodiments may provide
superior performance in harsh environments as it is able to provide
a relatively low viscosity increase, and relatively high sludge and
carbon varnish ratings over extended periods of time. It is
expected that a gear oil formulation as disclosed herein will
provide extended drain intervals without causing excessive wear of
vehicle components such as axles.
[0058] At numerous places throughout this specification, reference
has been made to a number of U.S. Patents. All such cited documents
are expressly incorporated in full into this disclosure as if fully
set forth herein.
[0059] Other embodiments of the present invention will be apparent
to those skilled in the art from consideration of the specification
and practice of the invention disclosed herein. As used throughout
the specification and claims, "a" and/or "an" may refer to one or
more than one. Unless otherwise indicated, all numbers expressing
quantities of ingredients, properties such as molecular weight,
percent, ratio, reaction conditions, and so forth used in the
specification and claims are to be understood as being modified in
all instances by the term "about." Accordingly, unless indicated to
the contrary, the numerical parameters set forth in the
specification and claims are approximations that may vary depending
upon the desired properties sought to be obtained by the present
invention. At the very least, and not as an attempt to limit the
application of the doctrine of equivalents to the scope of the
claims, each numerical parameter should at least be construed in
light of the number of reported significant digits and by applying
ordinary rounding techniques. Notwithstanding that the numerical
ranges and parameters setting forth the broad scope of the
invention are approximations, the numerical values set forth in the
specific examples are reported as precisely as possible. Any
numerical value, however, inherently contains certain errors
necessarily resulting from the standard deviation found in their
respective testing measurements. It is intended that the
specification and examples be considered as exemplary only, with a
true scope and spirit of the invention being indicated by the
following claims.
* * * * *