Note: Descriptions are shown in the official language in which they were submitted.
131 7~7~
~ 1 --
This invention relates generally to the field of
additives which are included within lubricant compositions
in order to improve performance characteristics of the
lubricants. More specifically, the invention relates to
additive compounds which act as corrosion inhibitors within
gear oil compositions, the corrosion inhibitors being in the
form of borated and non-borated forms of overhased
carboxylates.
The ability to inhibit corrosion, rust formation,
oxidation and deterioration is a very significant property
of lubricating compositions and functional fluids. The
;'~
.. .~,
~3~7278
-- 2 ~
significance o~ such properties becomes increasingly
important when the lubricant or functional fluid is used
in connection with very expensive equipment under severe
operating conditions. The significance of the ability to
inhibit corrosion is further emphasized when ~he
lubricant, such as a gear oil, is used in an environment
such that it comes into contact with water under e~treme
temperature and pressure conditions. In the absence of a
corrosion inhibitor with high performance characteristics
the useful life of the machinery will be substantially
reduced. Accordinglyt many manufacturers of equipment
requiring the use of functional fluids and lubricants
require that such fluids and lubricants contain corrosion
inhibitors. A number of tests have been devised in order
to rate the corrosion inhibiting properties of lubricants
and functional fluids when used under extreme conditions.
Accordingly, there is a significant need for corrosion
inhibitors which can be easily and economically
manufactured and provided in lubricants and functional
fluids in order to provide corrosion inhibiting
properties.
U.S. Patent 3,929,650 to King et al discloses a
particulate dispersion of an alkali metal borate. The
borate i5 prepared by contacting boric acid with an alkali
metal carbonate overbased metal sulfonate within an
oleophilic liquid reaction medium. The reactants are
contacted at a temperature in the range of 20~200C for a
period of 0.5-7 hours with the molar ratio of the boric
acid to the alkaline metal carbonate being in the range of
~rom 1-3.
U S. Patent 3,595,790 to ~lorman et al ~iscloses a
number of different oil soluble highly basic metal salts
of various organic acids. Salts of sulonic acids,
carboxylic acids and phosphorus acids are obtained by
reacting such acids with an excess amount of a metal base
in the presence of an acidic gas such as carbon dioxide
and a promoter such as alcohol under substantially
_ 3 _ ~3~727~
anhydrous conditions. The basic metal salts are indicated
as being useful as additives in crankcase oils (oils of
low viscosity compared to gear oils) in order to
neutralize undesirable acid bodies formed in crankcase
oils during engine operation.
SUMMARY OF THE INVENTION
The present invention is a corrosion inhibitor
additive compound which is used in connection with
lubricants in the form of gear oils. The corrosion
inhibitor addi~ive is in the form of an overbased
carboxylate which is preferably borated. The borated
versions of the overbased carboxylate additive of the
invention are most generally prepared by reacting a boron
reactant (preferably boric acid) with an overbased
carboxylate. The invention also relates to a method of
improving the corrosion inhibiting properties of a gear
oil comprising adding borated and/or non-borated versions
of the corrosion inhibitor of the invention to the gear
oil which contains small amounts (0.1~ to 5% based on the
weight of the gear oil) of contaminant water, and allowing
the corrosion inhibitor to disperse in the system and
thereby improve overall corrosion inhibiting properties.
An object of the present invention i5 to provide a
corrosion inhibitor useful in a wide range of lubricating
and functional fluid compositions and particularly in gear
oils.
An advantage of the present invention is that the
overbased carboxvlate composition of the invention can be
easily and economically manufactured and included within
lubricating compositions in the form of gear oils to
inhibit corrosion, rust formation, oxidation and
deterioration.
A feature of the present invention is that the
corrosion inhibitor additive can be provided in a variety
_ 4 ~ ~ 3~ ~ 7~
of overbased carboxylate forms. More specifically, the
carboxylate acid anion portion as well as the metal cation
portion of the molecule are readily available and
economical as is the optional borating agent.
Another advantage of the corrosion inhibitor
composition is that it can provide corrosion resistance
properties to a gear oil while not acting in a manner
which is antagonistic with respect to high speed score and
shock loading protection which antagonistic properties are
generally obtained by the use of free carboxylic acids,
another well known class of corrosion inhibitors.
Yet another advantage of the present invention is
that the corrosion inhibitors provide improved properties
to gear oils without having a undesirable effect on the
oxidation and/or thermal stability of the gear oils, which
undesirable effects are obtained when utilizing amine
compounds as corrosion inhibitors~
These and other objects, advantages and features of
the present invention will become apparent to those
persons skilled in the art upon reading the details of
formulation, synthesis and usage as more fully set forth
below. Reference being made to the accompanying general
structural formulae forming a part hereof wherein like
symbols refer to like molecular moieties throughout.
DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS
Before the present corrosion inhibitor additive,
process for making such additive, oil formulations, method
for improving corrosion, and additive concentrates are
described it is to be understood that this invention is
not limited to the particular chemical compounds
processes, formulations, methods, or concentrates
described as such compounds, processes, formulations and
concentrates, may, of course, vary. It is also to be
understood that the terminology used herein is for the
_ 5 _ ~3172~
purpose of describing particular embodiments only, and is
not intended to be limiting since the scope of the present
invention will be limited only by the appended claimsO
It must be noted that as used .in this specification
and the appended claims, the singular forms "a", "an" and
"the" include plural referents unless the context clearly
dictated otherwise. Thus, for example, reference to "an
overbased carboxylate," includes mixtures of such
carboxylates, reference to "a corrosion inhibitor"
includes reference to mixtures of such corrosion
inhibitors and reference to "oils" includes mixtures of
such oils and so forth.
The present invention provides a corrosion inhibitor
additive which can be used in connection with lubricants
and functional fluids. The additive is in the form of an
overbased carboxylate which can be in a borated or non-
borated form. It is pointed out that the borated versions
are generally preferred, and are prepared by reacting a
boron reactant ~preferably boric acid) with a an overbased
carboxylate. Overbased carboxylates are known to be used
in crankcase engine oils (oils of low viscosity compared
to gear oils) in order to neutralize acidic components
formed during engine operation. These acidic components
are formed by "engine blow back" a phenomenon which does
not occur in a rear axle assembly.
In connection with the present disclosure, the term
"overbased" or "overbased compound" or "overbased
carboxylate" is generally used to designate metal salts
wherein the metal ion is present in stoichiometrically
larger amounts than the organic acid radical. The
commonly employed methods for preparing overbased
compounds involve heating a mineral oil solution of an
acid (such as a carboxylic acid) with a stoichiometric
excess of a metal neutralizing agent such as the metal
oxide, hydroxide, carbonate, bicarbonate, or sulfide at a
temperature above 50C and ~iltering the resulting mass~
In connection with the production of overbased
- 6 - ~3~7~77~
compounds it is generally preferred to use a prornoter in a
neutralization step in order to aid in the incorporation
of a large excess of metal. A particularly effective
method of preparing an overbased carboxylate comprises
mixing a carboxylic acid with a stoichiometric excess of a
basic alkaline earth neutralizing agent such as calcium
hydroxide and at least one alcohol promoter and
carbonating the mixture by passing CO2 into the mixture at
an elevated temperature which may be in the range of 10C
to 200C but is more preferably in the range of about 40
to 80C.
The present inventor has found that the corrosion
inhibiting properties of various lubricating compositions
and functional fluids, specifically gear oil formulations,
can be greatly improved by including an additive in the
form of an overbased carboxylate which is preferably
borated. Such an overbased carboxylate is prepared by
reacting a stoichiometric excess of a metal neutralizing
agent with a statistical mixture of carboxylic acids to
form a statistical mixture of carboxylates which includes
a stoichiometric excess of the metal. The anion portion
of the present corrosion inhibitor is an ionized
carboxylic acid or ionized carboY~ylate and is most
preferably a statistical mixture of such. A statistical
mixture of components is a mixture consisting of a large
number of compounds which differ, one from the other, in
small increments (e.g. molecular weight and shape) over a
wide range. The cationic portion of the present corrosion
inhibitor is typically an ion of an alkali metal or an ion
of an alkaline earth metal. Some specific metals which
might be utilized include lithium, potassium, sodium~
magnesium, calcium and barium with sodium, calcium and
magnesium being preferred.
A number of different types of carboxylic acids may
be used individually or preferably in statistical mixtures
in producing the present invention. Useful carboxylic
acids include oleic acids, tall oil acids, pumitic acids,
_ 7 _ ~3~7~7~
linoleic acids, stearic acids and lauric aci~s. Other
carboxylic acids which are oil soluble or dispersible in a
salt form combination with other additives within
lubricants of functional Elulds can also be used in
connection with the present invention. Useful carboxylic
acids generally contain 12 to 22 carbon atoms.
The carboxylic acid component is converted to a salt
by reacting it with a metal neutralizing agent. The
neutralizing agent may be a metal by itself of a metal
oxide, hydroxide, caxbonate, bicarbonate or sulfide. Such
neutralizing agents may be used individually or preferably
in combination with each other in a statistical mixture.
Sodium, calcium and magnesium metals and metal compounds
are preferably used in connection with the present
inv~ntion. However, other alkali and alkaline earth
metals and compounds thereof may be used in connection
with producing the overbased carboxylates of the
invention~
The overbased carboxylates of the present inven-tion
can be obtained by reacting one or more of the carboxylic
acids or statistical mixtures thereof indicated above with
one or more of the neutralizing agents indicated above.
The neutralizing agents are to be added in stoichio
metrically larger amounts than the organic acid. Means o
carrying out the reaction between the organic acid and the
neutralizing agent have been indicated above. A typical
reaction might involve the reaction of calcium hydroxide
and oleic acid in order to form a calcium carboxylate,
more specifically, calcium oleate.
Such a reaction product could be referred to by the
following general empirical formula (I):
Ca(RCOO)2. XCalOH)2 ~ YCaCO3
wherein R is a hydrocarbyl and X and Y combined are
greater than one and vary depending on the degree of
overbasing desire. A range of different "R2" are present
- 8 - ~3~72~
in a preferred statistical mixture of the invention.
In formula (I) and elsewhere in the disclosure
hydrocarbyl means "hydrocarbon-based." As used herein,
the term "hydrocarbon-based," "hydrocarbon-based substi-
tuent" and the like denotes a substituent having a carbondirectly attached to the remainder of the molecule and
having predominantly hydrocarbyl character within the
context of this invention.
Examples of hydrocarbyl substituents which might be
useful in connection with the present invention include
the followingo
(1) hydrocarbon substituents, that is, aliphatie
(e g., alkyl or alkenyl), alicyclic (e.g., cycloalkyl,
cycloalkenyl) substituents, aromatic, aliphatic and
alicyclic-substituted aromatic nuclei and the like as well
as cyclic substituents wherein the ring is completed
through another portion of the molecule (that is, for
example, any two indicated substituents may together form
an alicyclic radieal);
(2) substituted hydroearbon substituents, that is,
those substituents containing nonhydrocarbon radicals
which, in the context of this invention, do no-t alter the
predominantly hydrocarbon substituent; those skilled in
the art will be aware of such radicals (e.g., halo
(especially chloro and fluoro), alkoxy~ mercapto,
alkylmercapto, nitro, nitroso, sulfoxy, etc.);
(3) hereto substituents, that is, substituents which
will, while having predominantly hydrocarbyl character
within the context of this invention, contain other than
carbon present in a ring or chain otherwise composed of
carbon atoms. Suitable heteroatoms will be apparent to
those of ordinary skill in the art and include, for
example, sulfur, oxygen, nitrogen and such substituents
as, e.g., pyridyl, furanyl, thiophenyl, imidazolyl, etc.,
are exemplary of these hereto substituents heteroatoms and
preferably no more than one, will be present for each ten
carbon atoms in the hydrocarbon-based substituerlts.
Typically, there will be no such radicals or heteroatorns
~7~
in the hydrocarbon-based substituent and it wi]l,
therefore, by purely hydrocarbon.
Some preferred carboxylic acids which are used in
preparing the overbased carboxylate include ~all oil fatty
acid, oleic, linoleic acid, and pumitic acids. Some
preferred neutralizing agents include sodium hydroxide,
calcium hydroxide and magnesium hydroxide. Statistical
mixtures of overbased calcium carboxylates are believed to
be particularly preferred.
After the overbased carboxylate has been formed it
may be borated by reacting the carboxylate with a boron
reactant. The boron reactant is preferably in the form of
boric acid. In order to carry out the reaction boric acid
is charged into the reaction medium containing the
overbased carboxylate in an amount necessary in order to
form the desired type of borate. Different amounts of
H3BO3 may be charged into the system to obtain the desired
amount of borate incorporation depending upon the desired
end results and the particular functional fluid or
lubricating compositions that the rust inhibitor is to be
used in connection with.
Useful boron reactants include, boric acid, and
various alkylborates such as tri-butylborate and sodium
metaborate with boric acid being preferred. The overbased
carboxylate can be completely or partially borated with
one or more boron reactants.
The overbased carboxylate rust inhibitor in its
borated and non borated versions may be present in a
lubricating composition or functional fluid such as a gear
oil in an amount sufficient to improve the rust inhibiting
performance characteristics of the lubricant or fluid.
This amount can be determined by those s~illed in the art
and varies depending on factors such as the type of oil
base, the end use, and other additives present in the
formulatlon. In general the rust inhibitor is present in
an amount in the range of from about 0.1% to 3%,
preferably from about 0.~% to about 1.5% and most
-10- ~3~7~7~
preferably about 0.5~ by weight based on the weigh-t of a
fully formulated lubricant or functional fluid.
The carboxylic acids from which suitable overbased
salts for use in this invention can be made include
aliphatic, cycloaliphatic, and aromatic mono- and
polybasic carboxylic acids such as the napthenic acids,
alkyl- or alkenyl-substituted cyclopentanoic acids, alkyl-
or alkenyl-substituted cyclohexanoic acids, alkyl- or
alkenyl-substituted aromatic carboxylic acids. The
aliphatic acids generally contain at least 8 carbon atoms
and preferably at least 12 carbon atoms. Usually they
have no more than about 400 carbon atoms. Generally, if
the aliphatic carbon chain is branched, the acids are more
oil-soluble for any given carbon atoms content. The
cycloaliphatic and aliphatic carboxylic acids can be
saturated or unsaturated. Specific examples include
2-ethylhexanoic acid, a-linolenic acid, propylene-
tetramer-substituted maleic acid, behenic acid, isostearic
acid, pelargonic acid, capric acid, palmitoleic acid,
linoleic acid, lauric acid, oleic acid, ricinoleic acid,
undecylic acid, dioctylcyclopentane carboxylic acid,
myristic acid, dilauryldecahydronaphthalene carboxylic
acid, stearyl-octahydroindene carboxylic acid, palmitie
acid, commercially available mixtures of two or more
carboxylic acids such as tall oil acids, rosin acids, and
the like. It is preferably to use a statistical mixture
of such aeids containing 12 to 400 carbon atoms.
A typical group of oil-soluble carboxylic acids
useful in preparing the salts used in the present inven-
tion are the oil-soluble aromatic carboxylic acids. These
acids are represented by the general formula:
r 11 1 (IV)
(R*)a~(Ar*) ~ -C-XH
_ _ m
wherein R* is an aliphatic hydrocarbon-based group of at
least 4 carbon atoms, and no more than about 400 aliphatic
3 ~ 7 2 7 ~
carbon atoms, a is an integer from one to four, Ar* is a
polyvalent aromatic hydrocarbon nucleus of up to abou-t 14
carbon atoms, each X* is independently a sulfur or oxygen
atom, and m is an integer of from one to four with the
proviso that R* and a are such that there is an a~erage of
at least 8 aliphatic carbon atoms provided by the R*
groups for each acid molecule represented by Formula IV.
Examples of aromatic nuclei represented by the variable
Ar* are the polyvalent aromatic radicals derived from
benzene, napthalene anthracene, phenanthrene, indene,
fluorene, biphenyl, and the like. Generally, the radical
represented by Ar* will be a polyvalent nucleus derived
from benzene or naphthalene such as phenylenes and
naphthylene, e.g., methyphenylenes, ethoxyphenylenes,
nitrophenylenes, isopropylenes, hydroxyphenylenes,
mercaptophenylenes, N,N-diethylaminophenylenes, chloro-
phenylenes, N,N-diethylaminophenylenes, chlorophenylenes,
dipropoxynaphthylenes, triethylnaphthylenes, and similar
tri-, tetra-, pentavalent nuclei thereof, etc.
The R* groups are usually hydrocarbyl groups, prefer-
ably groups such as alkyl or alkenyl radicals. However,
the R* groups can contain small number substituents such
as phenyl, cycloalkyl (e.g., cyc~ohexyl, cyclopentyl,
etc.) and nonhydrocarbon groups such as nitro, amino, halo
(e.g., chloro, bromo, etc.), lower alkoxy, lower alkyl
mercapto, oxo substituents (i.e., -O), thio groups (i.e.,
=S), interrupting groups such as ~ NH - , ~ O - , - S - , and
the like provided the essentially hydrocarbon character of
the R* group is retained. The hydrocarbon character is
retained for purposes of this invention so long as any
non-carbon atoms present in the R* groups do not account
for more than about 10% of the total weight of the R*
groups.
Examples of R* groups include butyl, isobu~yl,
pentyl, octyl, nonyl, dodecyl, docosyl, -tetracontyl,
5-chlorohexyl, 4-ethoxypentyl, 4~hexenyl, 3-cyclohexy~1-
octyl, 4-(p-chlorophenyl)-octyl, 2,3,5-trimethylheptyl,
3~ 7~7~
4-ethyl-5-methyloctyl, and substituents derived ~rom
polymerized olefins such as polychloroprenes, poly-
ethylenes, polypropylenes, polyisobutylenes, ethylene-
propylene copolymers, chlorinated olefin polymers,
oxidized ethylene-propylene copolymers, and the like.
Likewise, the group Ar~ may contain non-hydrocarbon
suhstituents, for example, such diverse substituents as
lower alkoxy, lower alkyl mercapto, nitro, halo, al~yl or
alkenyl groups of less than 4 carbon atoms, hydro~y,
mercapto, and the like.
The carboxylic acids corresponding to Formulae IV-V
above are well known or can be prepared according to
procedures known in the art. Carboxylic acids of -the type
illustrated by the above formulae and processes for
preparing their overbased metal salts are well known and
disclosed, or example, in such U.S. Pat. Nos. as
Z,197~832; 2,197,835; 2,252,662; 2,252,664; 2,71~,092;
3,410,798 and 3,595,791.
The following examples are provided so as to provide
those of ordinary skill in the art with a complete
disclosure and description of how to make the overbased
carboxylates, and lubricating formulations ~gear oils) o~
the invention. Accordingly, the examples are not intended
to limit the scope of what khe inventor regards as his
invention. Efforts have been made to ensure accuracy with
respect to the numbers and nomenclature used (e.g.
amounts, compounds, temperatures, etc.) but some
experimental errors and deviation should be accounted ~or.
Unles~ indicated otherwise, parts are parts by weight,
temperature is in degrees centigrade and pressure is at or
near atmospheric.
.. . .
~ 13 ~ 7~7~
EXA~P~E A
Add to a flask about 512 parts by weight of a mineral
oil solution containing about 0.5 equivalent of a
substantially neutral magnesium salt o an alkylated
salicylic acid wherein the alkyl group has an average of
about 18 aliphatic carbon atoms and about 250 parts by
weight of xylene. Heat to a temperature of about 60C to
70C. Increase the heat to about 85C and add appro-
ximately 60 parts by weight of water. Hold the reaction
10 mass at a reflux temperature of about 95C to 100C for
about 1-1/2 hours and subsequently strip at a temperature
of 155C-160C, under a v~cuum, and filter. The filtrate
will comprise the basic carboxylic magnesium salt
containing 200% of the stoichiometrically equivalent
amount of magnesium.
EXAMPLE B
Charge a reaction flask with about 506 parts by
weight of a mineral oil solution containing about 0.5
equivalent of a substantially neutral magnesium salt of an
alkylated salicylic acid wherein the alkyl groups have an
average of abou-t 16 to 2~ aliphatic carbon atoms together
with about 22 parts by weight (about 1.0 equlvalent) of a
magnesium oxide and about 250 parts by weight of xylene.
Heat to a temperature of about 60C to 70C. Increase the
temperature to about 85C and add approximately 60 parts
by weight of water to the reaction mass and heat to the
reflux temperature. Maintain the reaction mass at the
reflux temperature of about 95-100C for about 1-1/2
hours and subsequently strip at about 155C, under 40 torr
and filter. The filtrate comprise the basic carboxylic
magnesium sal-ts containing 274% of the stoichiometrically
equivalent amount of magnesium.
1~ - 13~ 72~
EXAMPLE C
Prepare a substantially neutral magnesium salt of an
alkylated salicylic acid wherein the alkyl groups have
from 16 to 24 aliphatic carbon atoms by reacting
approximately stoichiometric amounts of magnesium chloride
with a substantially neutral potassium salt of the
alkylated salicylic acid. Charge a flask with a reaction
mass comprising approximately 6580 parts by weight of a
mineral oil solution containing about 6.50 equivalents of
the substantially neutral magnesium salt of the alkylated
salicylic acid and about 388 parts by weight of an oil
mixture containing about 0.48 equivalent of an alkylated
benzenesulfonic acid together with approximately 285 parts
by weight (14 equivalents) of a magnesium oxide and
approximately 3252 parts by weight of xylene. Heat to a
temperature of about 55C to 75C. Increase the
temperature to about 82C and add approximately 780 parts
by weight of water to the reaction and then heat to the
reflux temperature~ Hold -the reaction mass at the reflux
temperature of about 95-100C for about 1 hour and
subsequently strip at a temperature of about 170C, under
50 torr and filter. The filtrate will comprise the basic
carboxyllc magnesium salts and have a sulfated ash content
of 15.7~ (sulfated ash) corxesponding to 276~ of the
stoichiometrically equivalent amount.
EXAMPLES A~l, B-l, C-l
Individual overbased carboxylates for any of EXAMPLES
A-C or mixtures of carboxylates from all or any of A-C can
be and preferably are borated by reacting with a suitable
borating agent such as boric acid to pxovide EXAMPLES A-l,
B-l, and C-1 respectively. The resulting borated
carboxylate provides improved anti-rust properties in
lubricants such as gear oils.
- 15 - 1 3~ ~ ~ 7~
E~AMPLE 1
Prepare a gear oil formulation by starting with a
base oil formulation utilized in making gear oils,
specifically SAE 80W-90 (80% 600N ~ 20% 150 sriyht Stock).-
Add to the base oil composition 0.25% by weight of aborated overbased carboxylate obtained by reacting the
overbased carboxylate of Example A with boric acid.
Thereafter add a suitable pour point depressant,
specifically the reaction product of a maleic
anhydride/styrene copolymer with alcohol and an amine, the
pour point depressant being added in an amount of 1 weight
percent. Add 1% of an amine-neutralized phosphate ester
and 0.075 weigh~ percent of an oleamide/linoleamide
mixture of hydroxyalkyl dialkyl-phosphorodithioate. Add
0.075 weight percent of polymeric anti-foaming agent and
add 3.5% o~ a sulfurized olefin~ Then add 0.08 weight
percent of an ashless inhibitor commercially sold as Amoco
158.
EXAMPLE 2
Formulate a gear oil by starting with a base oil
formulation utilized in making gear oils, specifically
Exxon Base SAE 80W-90. Add to the base oil composition
0.25~ by weight of an overbased carboxylate obtained by
the procedure of Example A. Thereafter add 1% by weight of
a pour point depressant ~a maleic anhydride/styrene
copolymer). Add 1% of an amine-neutralized phosphate ester
and ~.75 weight percent of an oleamide/linoleamide mixture
of hydroxyalkyl dialkylphosphorodithioate. Add 0.075
weight percent of a polymeric anti-foaming agent and add
3.6% of an sulfurized olefin as an antioxidant.
7 ,7 7 8
- 16 ~
EXAMPL _
Prepare a gear oil formulation starting with Exxon
Base SAE 80W-90~ Add to the base oil composition 0.10% by
weight of a borated overbased carboxylate obtained by
reacting the overbased carboxylate of Example B with boric
acid. Thereafter add a suitable pour point depressant,
specifically the reaction product of a maleic
anhydride/styrene copolymer with alcohol and an amine, the
viscosity improver being added in an amount of l weight
percent. Add 1% of an amine-neutralized phosphate ester.
Add 0.075 weight percent of a polymeric anti-foaming agent
and add 4.0% of an sulfurized olefin~
EXAMPLE 4
A gear oil formulation can be prepared by adding to a
15 base oil of Exxon Base SAE 80W-90 3.0% by weight of a
borated overbased carboxylate obtained by reacting the
overbased carboxylate of Example C wi-th boric acid.
Thereafter add 1.0% by weight of a suitable pour poin-t
depressant and 1% of an amine-neutralized phosphate ester.
Add 0.1% weight percent of a polymeric anti-foaminy agent
and add 2.0% of an sulfurized olefin. Then add 3.0 weight
percent of an epoxide treated dialkylphosphorodithioate.
EXAMPLE 5
A gear oil formulation was prepared starting with SE~
25 80W-90 base oil which was comprised of 75% by weight of
600 neutral oil and 25% of 150 bright stock. ~o the base
oil was added 1% by weight of pour point depressant in
the form of a a reaction product obtained by reacting a
maleic anhydride/styrene copolymer with ethanol and an
- 17 - ~3~7~
amine. An anti-wear agent (3% by weight) was added in the
form of an epoxide treated dialkylphsophorodithioate. One
weight % of borated calcium carboxylate was added, 0.1
weight % of R-NC3H6N (R is tallow~ and 0.075 weight % of a
polymeric anti-foam agent were added to complete the gear
oil formulation having improved anti-corrosion properties.
EXAMPLE 6
A gear oil formulation was prepared starting with SEA
80W-90 base oil which was comprised of 75% by weight of
600 neutral oil and 25% of 150 bright stock. To the base
oil was added 1-~ by weight of a reaction product obtained
by reacting a maleic anhydride/styrene copolymer with
ethanol and an amine as a viscosity index improver. An
anti-wear agent (3% by weight) was added in the form of an
epoxide treated dialkylphsophorodithioate. One weight %
of calcium carboxylate was added, 0.1 weight % of
R-NC3H6N (R is tallow~ and 0.075 weight % of a polymeric
antifoam agent were added to complete the gear oil
formulation having improved anti-corrosion properties.
EX~PLE 7
A gear oil formulation was prepared starting with SEA
80W-90 base oil which was comprised of 75% by weight o~
600 neutral oil and 25% of 150 bright stock. To the base
oil was added 1% by weight of a reaction product obtained
by reacting a maleic anhydride/styrene copolymer with
ethanol and an amine as a viscosity index improver. A
sulfurized olefin was added in an amount of 3% by
weight. An anti-wear agent (3% by weight) was added in
the form of an epo~ide treated dialkylphsophorodithioate.
- 18 - 13~7~7~
One weight ~ of a borated calcium carbox~late was added,
0.2 weight % of R-NC3H6N (R .is tallow) and 0.075 weight %
of a polymeric antifoam agent were added to complete the
gear oil formulation having improved anti-corrosion
properties.
COMPAP~ATIVE EXAMPLE 1
This example was prepared in the same manner as
Example 7 except that the 1 weight % of borated calcium
carboxylate was not added to the formulation.
COMPARATIVE EXAMPLE 2
Another comparative example was prepared in the same
manner followed within Example 7 except that 1 weight
% of calcium sulfonate was added to the formulation in
place of the 1 weight % of calcium carboxylate added in
Example 7.
CO~PARATIVE EXAMPLE 3
' Another comparative formulation was prepared in the
same manner as Example 7 except that 1 weight % of an
acidic rust inhibitor was added to the formulation in
place of the borated calcium carboxylate of Example 7.
COMPARATIVE EXAMPLE ~
Another comparative formulation was prepared
utilizing the same components put forth wi-thin Example 7
except that 1 weight % of an extra basic rust inhibitor
was added to the formulation in place of the borated
calcium carboxylate of Example 7.
~31~
- 19 ~
The above examples show the use of SAE 80W-90 oil as
the base oil. In preparing a gear oil SAE 80W-90 oil is
preferred but 75W to about 140W oils may be used and may
be used in combination with 150 bright stock oil. Base
oils used in preparing gear oils are 200 neutral or above,
preferably 3QON or abo~e and more preferably about 500N to
700N. The viscosity of a gear oil base oil is 40 cSt @
40C or high~r (6 cSt ~ 100C or higher~ preferably 60 cSt
~ 40C or higher (8 cSt @ 100C or higher). These
readings are well above those o~ base oils used as
lubricants in a crankcase e.g., 5 W and lOW base oil of
about lOON and about 20 cSt @ 40C t4 cSt @ 100C~.
The gear oil formulations o~ the presenk invention
typically include a suitable pour point depressant
compoun~. The pour point depressant compound is generally
present in an amount in the range of about O.05% to 4%,
more preferably 0.5% to 2% by weight based on thP weight
of the gear oil. A number of useful pour point depressant
compositions are known and are used in oils and fuels in
order to allow such to flow freely at lower temperatures.
Such compounds may typically be comprised o~ the
condensation product of a chlorinated para~fin and an
aromatic hydrocarbon such as naphthalene. A large number
of different pour point depressants and other publicatioIls
disclosing pour point depressants are disclosed and
described within PCT Publication US86/02792, published
August 30, 1987.
Gear oil formulations of the present invention also
typically include sul~urized olefin compounds which are
use~ul as anti-oxidants. Such compounds are typically
prepared by reacting unsaturated olefin compounds with
sulfurizing ayents such as hydrogen sulfide or elemental
sulfur under particular reaction conditions and possibly
in the presence o~ a catalyst. A number of sulfurized
olefin compositions are disclosed within PCT Publica~ion
~. ~
- 20 - 1 3
US86/0088~, published December 25, 198~.
The sulfurized compositions ~isclosed are prepared by
reacting at an elevated temperature, a sulfurizing agent with
at least one aliphatic olefin containing from abou-t 8 to
about 36 carbon atoms in the presence of a catalytic amount
of phosphoric acid, a phosphoric acid salt, phosphoric acid
ester or a mixture thereof. Preferably, the olefins will
contain about 8 to about 20 carbon atoms. The olefins may be
terminal olefins ~i.e., alpha-olefins), internal olefins or
mixtures thereof. The alpha-olefins are illustrated by 1-
octene, 1-decene, l-dodecene, 1-tetradecene, 1-hexadecene, 1-
octadecene, l-eicosene. The internal olefins may be
represented by the following general formula
CH3(CH2)nCH-cH-(cH2)~cH3
wherein n and m are independently inteyers from 0 to about
15 and the total number of carbon atoms is at least 8~
Examples of internal olefins include 2-octene, 2-dodecene, 9-
octadecene, 7-tetradecene, 7-hexadecene and 11-eicodecene.
Mixtures of two or more olefins are useful. One method for
preparing such mixtures of olefins is by the isomerization of
commercially available alpha-olefins, and the product of the
isomerization reaction is a mixture of olefins wherein the
double bond is in the 1,2,3,~, etc. position. Alternatively,
the mixtures of olefins may be obtained by fractionation or
by blending of olefins of various types and molecular
weights. The isomerization of terminal olefins is effected
by heating the olefin with mildly acidic catalysts such as
Amberlyst 15. Alpha-olefins, and particularly those
containing about 10 to about 20 carbon atoms are preferred.
Mixtures of such olefins are commercially available and are
particularly desirable for use in the present invention.
The olefins may be branched aliphatic olefins. Examples
of branched olefins include oligomers of propylene and
isobutylene such as propylene tetramer and triisobutylene.
J ~ ~ ~
- 21 -
The sulEurization reaction is carried out in the
presence of a catalytic amount of phosphoric acid, a
phosphoric acid salt, a phosphoric acid ester or a mixture
thereof. The phosphorus acid salts preferably are alkali
metal phosphates such as sodium monoacid orthophosphate,
potassium monoacid orthophosphate, and sodium diacid
orthophosphate. The alkali metal phosphates can be formed in
situ by merely adding an alkali metal hydroxide such as
sodium hydroxide and phosphoric acid to the mixture which is
to be sulfurized. The phosphoric acid esters useful as
catalyst may be mono- or di-alkyl esters containin~ up to
about 20 carbon atoms in each alkyl group. Examples of al~yl
groups include methyl, ethyl, propyl, pentyl, decyl, and
hexadecyl, etc.
The amount of phosphoric acid, phosphoric acid salt,
phosphoric acid ester, or mixtures thereof which is included
in the reaction in accordance with the present invention will
range from about 0.001 to about 5 parts by weight of the
catalyst per 100 parts of the aliphatic olefin. Lar~er
amounts of the catalyst may be used but are not necessary.
Althouyh phosphoric acid salts and esters can be utilized,
the sulfurization reaction is catalyzed by phosphoric aci.d
alone, and this catalyst is preferred. Generally, the
phosphoric acid will be introduced into the reaction mixture
as ~5~ phosphoric acid. The order of mixing the various
components is not critical although when an alkali metal
phosphate is to be utilized as a catalyst, the alkali metal
hydroxide initially is added to the reaction mixture ~hich is
heated, and thereafter, the phosphoric acid is added prior to
introduction of the sulfuri~ing agent.
The sulfurization reaction generally is effected at an
elevated temperature of from about 50 to about 350C/ more
preferably, at a temperature of from about 100 to about
250C. The reaction is effected with efficient agitation and
usually in an inert atmosphere such as nitrogen. If any of
- 22 - 131 7~ ~8
the reagents are appr~ciably volatile at the reaction
temperature, the reaction vessel may be sealed and maintained
under pressure. Although generally not necessary, the
reaction may be effected in khe presence of an inert solvent
such as an alcohol, ether, ester, ali.phatic hydrocarbon,
halogenated aromatic hydrocarbon, etc., which is a liquid
within the temperature range employed for the reaction.
The sulfuriziny agents useful in the process of the
present invention include sulfur, sulfur monochloride and/or
sulfur dichloride, a mixture of hydrogen sulfide and sulfur
or sulfur dioxide, etc. Preferably, the sulfurizing agent is
elemental sulfur. It is frequently advantageous to add the
sulfurizing agent portionwise to the mixture of the other
reagents. When elemental sulfur is utilized as a sulfurizing
agent, the reaction is exothermic which can be utilized as a
cost-cutting benefit. The amount of sulfur or sulfurizing
agent added to the reaction mixture can be varied over a wide
range although the amount included in the reaction mixture
should be an amount sufficient to provide a sulfurized
product containing the desired amount of sulfur which
generally is at least about 10~ by weight.
Following the sulfurization reaction, it is preferred
to remove substantially all low boiling materials, typically
by venting the reaction vessel, by sparging with an inert gas
such as nitrogen, by vacuum distillation or stripping, etc.
insoluble by-products may be removed by filtration if
necessary, usually at an elevated temperature (about 80~ -
120C).
A further optional step in the preparation of the
sulfurized compositions is the treatment of the sulfurized
product obtained as described above to reduce any active
sulfur which may be present. An illustrative method is the
treatment with an alkali metal sulfide. Other optional
treatments may be employed to improve product quality such as
odor, color, and staining characteristiGs of the sulfurized
- 23 ~ 7 2 7~
compositions.
The above-referred to PCT Publication US 86/008~4 also
refers to a number of other patents and publications which
disclose sulfurized olefin compositions and methods for
making such. Such sulfurized olefin compounds may be present
within a gear oil in an amount in the range of 0.5% to 10%,
more preferably 1~ to 5% and even more preferably in an
amount of about 2% by weight based on the total weight of
the gear oil.
The gear oil formulations of the present invention may
also include therein extreme pressure - anti-wear ag~nts.
Such compounds may be in the form of coupled phosphorus
containing amides. Such compounds are disclosed within
issued U.S. Patent 4,670,1G9.
Gear oil formulations of the invention may also include
other additives in minor amounts such as anti-foam a~ents
which are used to reduce or prevent the formation of stable
foam. Typical anti-foam agents include silicones or organic
polymers. Additional anti-foam compositions are described in
"Foam Control. Agents", by Henry T. Kerner ~Noyes Data
Corporation, 1976), pages 125-162.
In addition to the amine/phosphate ester compounds which
can be used within the gear oil formulations of the invention
it is possible to use various phosphorodithioate compounds
such as group II metal phosphorodithioates such as zinc
dicyclohexyl phosphorodithioate and okher similar compounds
as disclosed within U.S. Patent 4,670,169.
In addition to the components referred to abo~e it is
possible to include within the gear oil formulation other
!` .~ ^
.:. ,,
"3~,7~P118
additive components such as dispersants, detergents,
anti-oxidants, anti-wear agents, extreme pressure agents,
emulsifiers, demulsifiers, friction modifiers, other
anti-rust agents and corrosion inhibitors, viscosity
improvers, dyes and solvents to improve handleability.
These components may be present in various amounts
depending on the needs of the particular gear oil
formulation final product.
Widely accepted standard tests are available for
evaluating the ability of a material to prevent corrosion
or rust. Two of the most widely known and accepted
standardized tests are the L-33 Moisture Corrosion Test
and the ASTM D 665 Turbine Oil Rust Test IAmerican
Standard Testing Material, Book D, No. ~65). These tests
were shown to be useful in connection with the evaluation
of the above invention as compared with other gear oils
containing rust and ~orxosion inhibitors outside the
scope of the present in~ention.
The L-33 Moisture Corrosion Test will be described
first. Moisture which accumulates in a differential
assembly of a vehicle can create a severe rust problem.
A Dana Model 30 hypoid rear axle assembly is used in a
test specifically designed to evaluate corrosion
resistance characteristics of gear lubricants. The
lubxicant capacity is 1.2L (2 ~ pints). In order to run
the test 29.6 cm (one ounce) of distilled water is added
to the lubricant to increase the severity of the test.
The unit is motored at 2500 rpm for four hours at 82C
(180F) lubricant temperature. After the motoring period,
the assembly is stored for seven days at a temperature of
52C (125F). Following storage, the unit is disassembled
and the cover plate, differential case, gear teeth and
bearings are inspected for rust. In order to receive a
"pass" in the L-33 Moisture Corrosion Test no rust is
allowed on the gear teeth, bearings or any other
functioning part of the rear axle assemhly :[t should be
noted that the cover of the rear axle assembly is more
1~ 1 3~ 72 7~
susceptible to rust, and therefore may have no more than
1~ of the surface rusted in order to receive a "pass"
rating in accordance with the L-33 Moisture Corrosion
Test. Accordingly, if there is rust on any of the
functioning parts of the rear axle assembly or if there is
rust on more than 1% of the surface of the cover, a "fail"
rating is received. The L-33 Moisture Corrosion Test is
part of the MIL-L-2105C specification for gear lubricants,
and is recognized worldwide as a standard for rust
performance.
It is known that contamination of lubricants with
water can produce rapid rusting of the ferrous parts
unless the lubricants are adequately treated with an
appropriate rust inhibiting agent. The ASTM D 665
Turbine Oil Rust Test is designed to measure the ability
of industrial lubricants containing rust inhibitors to
prevent rusting under conditions of water contamination.
The ASTM D 665 Test consists of two parts. One part
of the test uses distilled water and the other part uses
a synthetic sea water. Both tests are run under identical
conditions and compared. The tests consist of stirring a
mixture of 300 ml of the test lubricant with 30 ml of
water at 60 (140F) for 24 hours. A special cylindrical
steel test specimen made from #1018 cold finished carbon
steel is completely immersed in the test fluid. At the
conclusion of the 24 hour period, the specimen is removed,
washed with a solvent and rated for rust.
In order to receive a "pass" in accordance with the
ASTM D 665 Turbine Oil Rust Test, the specimen must be
completely free of visible rust when examined under
magnification under normal light. When rust is observed
the tested lubricant receives a "fail" rating.
The L-33 Moisture Corrosion Test as well as the ASTM
D 665 Turbine Oil Test were run on lubricants encompassed
the present invention. For comparison purposes the same
lubricants which did not include the essential components
of the present invention were also tested by the above
~ 13~727~
described standard tests. The results are as follows:
Formulation Test Rating
EXAMPLE 7 L33 Pass
D665 Pass
COM EX 1 L33 Fail
D665 Fail
COM EX 2 L33 Fail
D665 Fail
COM EX 3 L33 Fail
D665 Fail
COM EXq L33 Fail
D655 Fail
In that comparative Examples 1-4 were the same as
Example 7 but for changes regarding the carboxylate
components it is believed that these results clearly
demonstrate the importance of the present invention
regarding the prevention of rust.
The instant invention is shown and descrlbed herein
in what is considered to be the most practical, and
preferred, embodiments. It is recognized, however, that
departures may be made therefrom which are within -the
scope of the invention, and that obvious modifications
will occur to one skilled in the art upon reading this
disclosure.
