Note: Descriptions are shown in the official language in which they were submitted.
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1
LUBRICANT COMPOSITIONS CONTAINING ALKOXYLATED AMINE
AND SULFURIZED HYDROCARBYL PHENOL FRICTION MODIFIERS
BACKGROUND OF THE INVENTION
1. Field of the Invention
This invention relates to lubricating oil compositions which
exhibit enhanced fuel economy and which contain a minor amount
of the friction modifier combination of an alkylated phenol
sulfide and an alkoxylated hydrocarbyl amine.
2. Description of Related Art
It is an object of the automotive and oil industry to provide
lubricating oil compositions which exhibit improvements in fuel
savings in gasoline and diesel engine vehicles. In order to meet
these goals, additives have been developed for crankcase and
transmission oils which significantly reduce friction between
engine or transmission moving parts, which reduction translates
into improved mileage per volume of fuel consumed by an internal
combustion engine. Because modern day lubricating oil
compositions are complex formulations, such additives must be
compatible with other components present in the oil and should
not adversely affect the numerous other functions of conventional
lubricant additives such as
2
dispersancy, viscosity stability, corrosion, oxidation inhibition and the
like.
Representative examples of known oil additive modifiers are found in U.S.
Patent No.
3,933,659 which discloses fatty acid esters and amides; U.S. Patent No.
4,176,074
which describes molybdenum complexes of polyisobutenyl succinic anhydride-
amino
alkanols; U.S. Patent 4,105,571 whicfi discloses glycerol esters of dimerized
fatty
acids; U.S. Patent No. 3,779,928 which discloses alkane phosphonic acid salts;
U.S.
Patent No. 3,778,375 which discloses reaction products of a phosphonate and
oleamide; U.S. Patent No. 3,852,215 which discloses S-carboxy-alkylene
hydrocarbyl
succinimide, S-carboxyalkylene hydrocarbyl succinic acid and mixtures thereof;
U.S.
Patent 3,879,306 which discloses N-(hydroxy-alkyl) alkenyl-succinamic acids or
succinimides; U.S. Patent No. 3,932,290 which discloses reaction products of
di-
(lower alkyl) phosphites and epoxides; and U.S. Patent No. 4,028,258 which
discloses the alkylene oxide adduct of phosphosulfurized N-(hydroxyalkyl)
alkenyl
succinimides.
Another known category of friction modifiers includes alkoxylated hydrocarbyl
mono
or polyamines such as generally illustrated by formulas 1 and 2 below. These
amines
include materials such as N,N-bis(2-hydroxyalkyl) hydrocarbyl amines such as
disclosed in U.S. Patents 3,711,406, 3,796,662, 3,933,659, 4,010,106,
4,129,508, 4,170,560, 4,231,883 and 4,795,583.
.,. .
3
In addition, U.S. Patent 4,086,172 discloses an additive combination for
lubricating
oils comprising a mixture of an oil soluble hydroxy amine such as an
alkoxylated fatty
amine and an oil soluble antioxidant component such as an aromatic sulfide.
The
mixture is said to impart improved antioxidant properties into the oil.
U.S. Patent 4,938,880 discloses lubricant compositions which may contain a
metal
salt of a phenol sulfide and a friction modifier.
U.S. Patent 4,764,294 discloses a lubricating oil additive combination
comprising a
metal phosphate, a metal carbamate and an alkyl hydroxyl aryl sulfide (nonyl
phenol
sulfide). The combination of these three additives is said to provide a
synergistic
improvement in imparting anti-wear and friction reducing properties.
U.S. Patent 4,587,026 discloses an oil additive useful for friction reduction
and
improved stability. This additive is an amine sulfurized concentrate prepared
by
forming the reaction product of an alkylated phenol sulfide, a boron-
containing
compound and an alkoxylated amine which may include bis(2-hydroxy ethyl)
oleamide. The evident structure of the reaction product is shown in claim 22
of this
patent.
The present invention is based on the discovery that a combination of one or
more
alkoxylated hydrocarbylamines and one or more alkylated phenol sulfides, as
defined
herein, added to lubricating oil compositions in specific proportions imparts
a
6 --
4
more enhanced friction modifying property to the lubricant than an equivalent
quantity
of either component alone.
SUMMARY OF THE INVENTION
The present invention provides an improved lubricating oil composition for
automotive
internal combustion engines and transmissions which comprises an oil of
lubricating
viscosity having admixed therewith a minor amount of friction modifier
composition
which reduces the coefficient of friction between moving mechanical parts,
thereby
providing for enhanced fuel economy. The friction modifier composition
comprises
a combination of an alkoxylated hydrocarbyl amine and an alkylated phenol
sulfide.
This combination of components provides for synergistic fuel economy effects,
particularly when used as components in automotive crankcase lubricants also
containing conventional additive packages, which effects are not observed in
oil
which contains one or the other of these components alone.
DETAILED DESCRIPTION
The alkoxylated amines which are suitable as one component of the friction
modifier
composition of
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this invention have the general formula l:
~R ~O ~"a. H
c ~ R s0~ H
( R o~ H
and also includes boronated derivatives thereof, wherein R1 is a
branched or straight chain hydrocarbyl group containing from
about 8 to about 30 carbon atoms, R2 and R3 are independently the
same or different branched or straight chain alkylene radicals
containing 1 to 6 carbon atoms, R4, RS and R6 are independently
the same or different alkylene radicals containing from 2 to 4
carbon atoms, X is oxygen or sulfur, p is 0 or an integer ranging
from 1 to 20, t is independently 0 or l, and a, b and c are
independently integers ranging from 1 to 4. In the more preferred
embodiment, R1 is a saturated or ethylenically unsaturated
hydrocarbyl group containing from 12 to 24 carbon atoms, Rz and
R3 independently contain 2-4 carbon atoms, R9, RS and R6
independently contain 2 or 3 carbon atoms, X is oxygen and a, b
and c are independently integers of 1 or 2. In the above formula,
both p and t may be 1 or either p or t may be 1 when the other
of them is 0, or p may be 1-20 when t is 0.
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In the most preferred embodiment, the alkoxylated amine is a
monoamine subgenus of formula l, where p and t are each 0, having
the formula 2:
i (R ~O ~-~. N
2. R -y
R so~ H
wherein R1, R9, R5, a and b are as set forth above.
In the most preferred embodiment of the invention as set forth
in formula 2, R1 is a saturated or ethylenically unsaturated
hydrocarbyl group having from 12 to 24 carbon atoms, particularly
a group derived from tallow amine, oleyl amine, stearyl amine,
lauryl amine, behynyl amine and the like as well as mixtures
thereof, RQ and RS each contain 2 or 3 carbon atoms, and
a = b = 1.
Illustrative of more preferred alkoxylated amines within the
scope of this invention include N,N',N'-tri(2-hydroxyethyl)
N-octadecyl propylene diamine, N,N',N'-tri(2-hydroxyethyl)
N-octadecenyl propylene diamine, N,N',N'-tri(2-hydroxyethyl)
N-hexadecyl propylene diamine, N,N',N'-tri(3-hydroxypropyl)
N-octadecadienyl propylene diamine, N,N',N'-tri(2-hydroxyethyl)
N-octadecyl ethylene diamine, N,N',N'-tri(2-hydroxyethyl)
N-octadecenyl ethylene diamine, N,N',N'-tri(2-hydroxyethyl)
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N-tetradecyl propylene diamine, N,N-di(2-hydroxyethyl)
oleyl amine, N,N-di-(2-hydroxyethyl) stearyl amine,
N,N-di(3-hydroxypropyl) tetradecyl amine, N,N-di(2-hydroxyethyl)
octadecylamine, N,N-di(2-hyroxyethyl) eicosylamine,
N,N-di(2-hydroxyethyl) tallowamine, N,N-di(2-hydroxypropyl)
tallowamine, N-(2-hyroxyethyl)-N-(hydroxyethoxyethyl)-n-
dodecylamine
N,N-di(2-hydroxyethyl)-1-methyl-undecylamine,
N,N-di(2-hydroxyethoxyethoxyethyl)-1-ethyl-octadecylamine,
N,N-di(2-hydroxyethyl)-n-dodecyloxethylamine,
N,N-di(2-hydroxyethyl)-lauryloxyethylamine,
N,N-di(2-hydroxyethyl)-stearyloxyethylamine,
N,N-di(2-hydroxyethyl)-n-dodecyloxpropylamine,
N,N-di(2-hydroxyethyl)-stearyloxypropylamine,
N,N-di(2-hydroxyethyl)-dodecylthioethylamine,
N,N-di(2-hydroxyethyl)-dodecylthiopropylamine,
N,N-di(2-hydroxyethyl)-hexadecylthioethylamine,
N,N-di(2-hydroxyethyl)-hexadecylthiopropylamine,
N-2-hydroxyethyl,N-[N',N'-bis(2-hydroxyethyl)
ethylamine]-octadecylamine,
N-2-hydroxyethyl,N-[N',N'-bis(2-hydroxyethyl)
ethylamine]-stearylamine, and the like, as well as boronated
derivatives thereof.
Illustrative of the most preferred alkoxylated amines are those
of formula 2 and wherein RQ and RS each have 2 carbon atoms and
include:
N,N-bis(2-hydroxyethyl) tallow-amine
N,N-bis(2-hydroxyethyl)-n-dodecylamine
N,N-bis(2-hydroxyethyl)-1-methyl-tridecenylamine
N,N-bis(2-hydroxyethyl)-hexadecylamine
N,N-bis(2-hydroxyethyl)-octadecylamine
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N,N-bis(2-hydroxyethyl)-octadecenylamine
N,N-bis(2-hydroxyethyl)-oleylamine
N,N-bis(2-hydroxyethyl)-stearylamine
N,N-bis(2-hydroxyethyl)-undecylamine
and boronated derivatives thereof.
The hydroxyl amine compounds may be used as such. However they
may also be used in the form of an adduct or reaction product
with a boron compound, such as a boric oxide, a boron halide, a
metaborate, boric acid, or a mono-, di-, or triorgano borate,
such as a mono-, di-, and trialkyl borate. Such adducts or
derivatives may be prepared by contacting the above amines with
a boronating agent. Preferred boronation agents include boric
acid and boric acid esters, e.g., tributyl borate. A
stoichiometric amount of the boronating agent relative to the
hydroxy groups present in the amine can be used or an excess of
boronating agent of up to a 50-100o excess or more can be used
and is often desirable for certain applications. Thus, boronation
can be complete or partial. Usually boronation levels vary from
about 0.05 to about 7 weight o of boron in the boronated
derivative.
Preferably the boronated derivatives are prepared in the presence
of an alcoholic or hydrocarbon solvent. The presence of a solvent
is not essential, however. If one is used, it may be reactive or
non-reactive. Suitable non-reactive solvents include benzene,
toluene, xylene and the like. Suitable reactive solvents include
isopropanol, butanol, the pentanols and the like. Reaction
temperatures may vary from about 70~ to
.~.,..,
~<
0 9 0~ ~ ~ oa
abut Z50 C with about l10 to about 1 0 C being
preferred.
The second essential component of the friction
modifier composition of this invention is one or a
mixture of hydrocarbyl phenol sulfides having. the
following general formula 3:
R~ R~ Ra R~
3. Ra ~ 5x ' 5x-.--,- ~ Rs
I 1
OH OH n OH
wherein R~ and R8 may be hydrogen or the same or
different hydrocarbyl radicals containing from
about 5 to 40 carbon atoms, at least one of R~ or
R8 being a hydrocarbyl radical, x is an integer of
from 1 to 4 , and n is 0 or an integer of from 1 to
4. In the preferred embodiment, R~ is an alkyl
group of sufficient chain length to render the
phenol sulfide compound oil soluble and preferably
contains an average of from about 8 to 20 carbon
atoms, n is 0, 1 or 2, preferably 0, x is 1 or 2,
preferably I and R8 is hydrogen. In the most
preferred embodiment of this invention, R~ is
located in a position para to the hydroxyl group
and sulfur is linked to the aromatic nucleus at
positions ortho to the hydroxyl group.
The hydrocarbyi phenol sulfides are known materials
which have been used in lubricant compositions
primarily as antioxidants. They may be readily
CA 02132523 1999-04-28
prepared by the direct sulfurization of hydrocarbyl phenols or
by reaction with a sulfur halide such as sulfur dichloride or
sulfur monochloride. The reaction product generally comprises
mixed phenol sulfide isomers, with the specific isomers described
above forming the major component of the mixture.
The preferred phenol sulfides for use in this invention are based
primarily on Cg through C16 phenol monosulfides and include para
nonylphenol monosulfide and para dodecylphenol monosulfide as the
primary isomers.
The lubricating oil base into which the friction modifier
composition of this invention may be incorporated includes
automotive crankcase and transmission oils of lubricating
viscosity for both diesel and gasoline engines, including natural
and synthetic lubricating oils and mixtures thereof.
Natural oils include animal oils and vegetable oils such as
castor oil or lard oil, liquid petroleum oils and hydrorefined
oils, solvent-treated or acid-treated mineral lubricating oils
of the paraffinic, naphthenic and mixed paraffinic-naphthenic
types. Oils of lubricating viscosity derived from coal or shale
are also useful base oils.
Synthetic lubricating oils include hydrocarbon and halo-
substituted hydrocarbon oils such as polymerized and
interpolymerized olefins (e. g., polybutylenes, polypropylenes,
propylene-isobutylene copolymers, chlorinated
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polybutylenes, poly(1-hexenes), poly(1-octenes), poly(1-decenes);
alkylbenzenes (e. g., dodecylbenzenes, tetradecylbenzenes,
dinonylbenzenes, di(2-ethylhexyl) benzenes); and polyphenyls
(e. g., biphenyls, terphenyls, alkylated polyphenols).
Alkylene oxide polymers and interpolymers and derivatives thereof
where the terminal hydroxyl groups have been modified by
esterification or etherification constitute another class of
known synthetic lubricating oils. These are exemplified by
polyoxylalkylene polymers prepared by polymerization of ethylene
oxide or propylene oxide, and include the alkyl and aryl ethers
of these polyoxyalkylene polymers such as methyl-polyisopropylene
glycol ether having an average molecular weight of l000, diphenyl
ether of poly-ethylene glycol having a molecular weight of 500-
1000, diethyl ether of polypropylene glycol having a molecular
weight of l000-1500, and mono- and polycarboxylic esters thereof
such as acetic acid esters, mixed C3 to C6 fatty acid esters and
the C13 Oxo acid diester of tetraethylene glycol.
Another suitable class of synthetic lubricating oils comprises
one or more esters of dicarboxylic acids (e. g., phthalic acid,
succinic acid, alkyl succinic acids and alkenyl succinic acids,
malefic acid, azelaic acid, suberic acid, sebasic acid, fumaric
acid, adipic acid, linoleic acid dimer, malonic acid,
alkylmalonic acids and alkenyl malonic acids) with a variety of
alcohols (e. g., butyl alcohol, hexyl alcohol, dodecyl alcohol,
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2-ethylhexyl alcohol, ethylene glycol, diethylene glycol
monoether and propylene glycol). Specific examples of these
esters include dibutyl adipate, di(2-ethylhexyl) sebacate,
di-n-hexyl fumarate, dioctyl sebacate, diisooctyl azelate,
diisodecyl azelate, dioctyl phthalate, dodecyl phthalate,
dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid
dimer, and the complex ester formed by reacting one mole of
sebacic acid with two moles of tetraethylene glycol and two moles
of 2-ethylhexanoic acid.
Esters useful as synthetic oils also include those made from CS
to C12 monocarboxylic acids and polyols and polyol ethers such as
neopentyl glycol, trimethylolpropane, pentaerythritol,
dipentaerythritol and tripentaerythritol.
Silicon-based oils such as the polyalkyl, polyaryl-polyalkoxy-,
or polyaryloxysiloxane oils and silicate oils comprise another
useful class of synthetic lubricants. These include tetraethyl
silicate, tetraisopropyl silicate, tetra-(2-ethylhexyl) silicate,
tetra-(4-methyl-2-ethylhexyl) silicate tetra-(p-tert-butyl-
phenyl) silicate, hexa-(4-methyl-2-pentoxy) disiloxane,
poly(methyl)siloxanes and poly(methylphenyl) siloxanes. Other
synthetic lubricating oils include liquid esters of phosphorus-
containing acids (e. g., tricresyl phosphate, trioctyl phosphate,
diethyl ester of decylphosphonic acid) and polymeric
tetrahydrofurans.
Unrefined, refined and rerefined oils can be used in the
lubricants of the present invention.
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Unrefined oils are those obtained directly from a natural or
synthetic source without further purification treatment. For
example, a shale oil obtained directly from retorting operations,
a petroleum oil obtained directly from distillation or ester oil
obtained directly from an esterification process and used without
further treatment would be an unrefined oil. Refined oils are
similar to the unrefined oils except they have been further
treated in one or more purification steps to improve one or more
properties. Many such purification techniques, such as
distillation, solvent extraction, acid or base extraction,
filtration and percolation are known to those skilled in the art.
Rerefined oils are obtained by processes similar to those used
to obtain refined oils, but applied to refined oils which have
been already used in service. Such rerefined oils are also known
as reclaimed or reprocessed oils and often are additionally
processed by techniques for removal of spent additives and oil
breakdown products.
The components of the friction modifier composition of this
invention are each blended into the lube oil base stock in
amounts which reduce the friction coefficient between the
mechanical parts of the engine or other apparatus in which they
are used, thereby enhancing fuel economy. Generally speaking, the
amount of alkoxylated amine added to the base oil will range from
about 0.05 to l.Oo by weight, more preferably from about 0.1 to
0.5o by weight. The amount of hydrocarbyl phenol sulfide added
to the base oil will range from about 0 . 1 to 2. 5 o by weight, more
preferably from about 0.2 to
14
1.0% by weight. The preferred Weight ratio of the
alkoxylated amine to the phenol sulfide is in the
range of from about 0.2 to 2.5:1 respectively, more
preferably from about 0.4 to 1.5:l respectively.
Most preferably the phenol sulfide is present in an
amount in excess of the amount of the amine,
preferably at least about a 2 to 1 to 5 to 1 weight
excess.
The lubricant oil of this invention is preferably
also admixed with one or more additional additives
to form a fully formulated oil. Such additives
include dispersants,~ detergents, oxidation
inhibitors, viscosity modifiers, corrosion
inhibitors, other friction modifiers, antifoaming
agents, anti wear agents and the like.
Suitable dispersants which may be employed are
known in the art. A preferred class of dispersant
are the ashless dispersants which are normally
nitrogen-containing, oil-soluble salts, amides,
imides or esters of mono or dicarboxylic acids. A
particularly preferred dispersant is the reaction
product of a polyolefin-substituted succinic
anhydride such as polyisobutenyi succinic anhydride
and an alkylene polyamine, which can be further
treated with a source of boron or copper. Such a
material is disclosed in U.S. Patent 4,938,880. Such
dispersants are generally added to the oil in amounts
ranging from about 0.1 to about loo by weight.
Metal containing rust inhibitors and/or detergents
are frequently used with ashless dispersants. Such
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detergents and rust inhibitors include the metal salts of
sulphonic acids, fatty acid esters such as glycerol mono and/or
di stearate (which also function as friction modifiers), alkyl
phenols, sulfurized alkyl phenols, alkyl salicylates,
naphthenates, and other oil soluble mono- and di-carboxylic
acids. Highly basic, that is overbased metal salts, which are
frequently used as detergents include calcium or magnesium
phenates, sulfurized phenates and/or sulfonates. Usually these
metal containing inhibitors and detergents are used in
lubricating oil in amounts of about 0.01 to 10 wt. o, more
preferably about 0.1 to 5 wt. o, based on the weight of the total
lubricating composition. Marine diesel lubricating oils typically
employ such metal-containing rust inhibitors and detergents in
amounts up to about 20 wt. o.
The Tube oil may also contain one or more suitable antioxidants
and/or oxidation inhibitors. Suitable antioxidants include
phenols, hindered phenols, bis-phenols, sulfurized phenols,
catechol, alkylated and sulfurized alkylated catechols,
diphenylamine, alkylated diphenylamines and phenyl-1-
naphthlamines, alkyl and aryl borates, phosphites and phosphates,
trialkyl and triaryl dithiophosphates and the like. Other
antioxidants include oil soluble copper compounds. The copper
compound may be in the cuprous and cupric form. The copper may
be in the form of copper dihydrocarbyl thio- or dithio-
phosphates. Alternatively the copper may be added as the copper
salt of a synthetic or natural carboxylic acid. Examples include
Clo to C18 fatty acids such as
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stearic or palmitic. Unsaturated acids such as oleic or branched
carboxylic acids such as napththenic acids of molecular weight
from 200 to 500 or synthetic carboxylic acids are preferred
because of the improved handling and solubility properties of the
resulting copper carboxylates. Also useful are oil soluble copper
dithiocarbamates. Copper sulphonates, phenates, and
acetylacetonates may also be used. The copper antioxidant can
comprise a copper salt of a hydrocarbyl substituted C9 to Clo
monounsaturated dicarboxylic acid producing reaction product,
which reaction product is formed by reacting a polymer of a C2 to
Clo monoolefin having a number average molecular weight of 900 to
1400 (e.g., 700 to 1200) substituted with a C9 to Clo
monosaturated acid material. Exemplary are copper salts of a
hydrocarbyl substituted CQ to Clo monounsaturated dicarboxylic
acid producing reaction product, which reaction product is formed
by reacting a polymer of C2 to Clo monoolefin having a number
average molecular weight of from 900 to 1400 substituted with
succinic moieties selected from the group consisting of acid,
anhydride and ester groups, wherein there is an average of about
0.8 to 1.6 molar proportions of succinic moieties per molar
proportion of the polymer.
The copper antioxidants will generally be added to the oil in an
amount of from about 50-500 ppm by weight of the metal.
Corrosion inhibitors, also known as anti-corrosive agents, reduce
the degradation of the metallic parts contacted by the
lubricating oil composition.
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Illustrative of corrosion inhibitors are phosphosulfurized
hydrocarbons and the products obtained by reaction of a
phosphosulfurized hydrocarbon with an alkaline earth metal oxide
or hydroxide, preferably in the presence of an alkylated phenol
or of an alkylphenol thioester, and also preferably in the
presence of carbon dioxide. Phosphosulfurized hydrocarbons are
prepared by reacting a suitable hydrocarbon such as a terpene,
a heavy petroleum fraction of a CZ to C6 olefin polymer such as
polyisobutylene, with from 5 to 30 weight percent of a sulfide
of phosphorus for 0.5 to 15 hours, at a temperature in the range
of l50~ to 600~C. Neutralization of the phosphosulfurized
hydrocarbon may be effected in the manner taught in U.S. Patent
l,969,324.
Oxidation inhibitors reduce the tendency of mineral oils to
deteriorate in service which deterioration can be evidenced by
the products of oxidation such as sludge and varnish-like
deposits on the metal surfaces and viscosity growth. Such
oxidation inhibitors include alkaline earth metal salts of
alkylphenolthioesters having preferably CS to Ciz alkyl side
chains, calcium nonylphenol sulfide, barium t-octylphenyl
sulfide, dioctylphenylamine, phenylalphanaphthylamine,
phosphosulfurized or sulfurized hydrocarbons, etc.
Pour point depressants lower the temperature at which the oil
will flow or can be poured. Such depressants are well known.
Typical of those additives which usefully optimize the low
temperature fluidity of the oil are Ca-Cla
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dialkylfumarate/vinyl acetate copolymers, polymethacrylates, and
wax napthalene.
Foam control can be provided by an antifoamant of the
polysiloxane type, e.g. silicone oil and polydimethyl siloxane.
Another class of additive that can be included in the oil are the
dihydrocarbyl dithiophosphate metal salts which are frequently
used as anti-wear agents and which also provide antioxidant
activity. These compounds may be generally characterized by the
formula
Rq0'
'PSS n M
R ~~
wherein R9 and R1~ are each independently hydrocarbyl groups
containing from 3 to about 13 carbon atoms, M is a metal and n
is an integer equal to the valence of M. The hydrocarbyl groups
in the phosphorodithioate structure include alkyl, cycloalkyl or
alkaryl groups which may contain ether or ester linkages and
which may also contain substituent groups such as halogen or
nitro. Illustrative alkyl groups include isopropyl, isobutyl, n-
butyl, sec-butyl, amyl, n-hexyl, methylisobutyl carbinyl, heptyl,
2-ethylhexyl, diisobutyl, isooctyl, nonyl, behenyl, decyl,
dodecyl, tridecyl, etc. Illustrative lower
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19
alkylphenyl groups include xylyl, cresyl, butylphenyl,
amylphenyl, heptyl-phenyl, etc. Cycloalkyl groups likewise are
useful and these include chiefly cyclohexyl and the lower alkyl-
cyclohexyl radicals. Many substituted hydrocarbon groups may also
be used, e.g., chloropentyl, dichlorophenyl, and dichlorodecyl.
These compounds are prepared by first forming the relevant
phosphorodithioic acid and then reacting this product with a
suitable metal containing compound.
The phosphorodithioic acids are prepared by the reaction of
phosphorus pentasulfide with an alcohol or phenol or mixtures of
alcohols, mixtures of phenols or mixtures of alcohols and
phenols. The reaction involves four moles of the alcohol or
phenol per mole of phosphorus pentasulfide, and may be carried
out within the temperature range from about 50~C to about 200~C,
preferably from about 50~C to about l50~C. Thus the preparation
of 0,0-di-n-hexyl phosphorodithioic acid involves the reaction
of phosphorus pentasulfide with four moles of n-hexyl alcohol at
about 100~C for about two hours. Hydrogen sulfide is liberated
and the residue is the defined acid. The preparation of the metal
salt of this acid may be effected by reaction with metal oxide.
Simply mixing and heating these two reactants is sufficient to
cause the reaction to take place and the resulting product is
sufficiently pure for the purposes of this invention.
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The metal salts of dihydrocarbyl phosphorodithioates which are
useful in this invention include those salts containing Group I
metals, Group II metals, aluminum, lead, tin, manganese, cobalt,
and nickel. The Group II metals, tin, iron, cobalt, lead,
manganese, nickel and copper are among the preferred metals. Zinc
and copper are especially useful metals. Examples of metal
compounds which may be reacted with the acid include lithium
oxide, lithium hydroxide, sodium hydroxide, sodium carbonate,
potassium hydroxide, potassium carbonate, silver oxide, magnesium
oxide, magnesium hydroxide, calcium oxide, zinc hydroxide, zinc
oxide, copper oxide, strontium hydroxide, cadmium oxide, cadmium
hydroxide, barium oxide, iron carbonate, copper hydroxide, lead
hydroxide, tin butylate, cobalt hydroxide, nickel hydroxide,
nickel carbonate and the like.
In some instances, the incorporation of certain ingredients such
as small amounts of the metal acetate or acetic acid in
conjunction with the metal reactant will facilitate the reaction
and result in an improved product. For example, the use of up to
about 5% of zinc acetate in combination with the required amount
of zinc oxide facilitates the formation of a zinc
phosphorodithioate.
In one preferred embodiment, the alkyl groups R9 and R1~ in the
formula above are derived from secondary alcohols such as
isopropyl alcohol, secondary butyl alcohol, 2-pentanol,
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4-methyl-2-pentanol, 2-hexanol, 3-hexanol, as well as mixtures
thereof.
These compounds are generally incorporated into the lubricating
oil formulation in the range of from about 0.0l to about 5o by
weight, more preferably from about 0.1 to about 3o by weight.
The preferred compounds are the zinc dihydrocarbyl
dithiophosphites.
Viscosity modifiers impart high and low temperature operability
to the lubricating oil and permit it to remain relatively viscous
at elevated temperatures and also exhibit acceptable viscosity
or fluidity at low temperatures. Viscosity modifiers are
generally high molecular weight polymers, including polyesters,
polymethacrylates, polyacrylates and polyolefins. The viscosity
modifiers may also be derivatized to include other properties or
functions, such as the addition of dispersancy properties. These
oil soluble viscosity modifying polymers will generally have
number average molecular weights of from 103 to 106, preferably
109 to 106, e.g., 20,000 to 250,000, as determined by gel
permeation chromotography or osometry.
Examples of suitable hydrocarbon polymers include homopolymers
and copolymers of two or more Cz to C3o olefin monomers, e.g. Cz
to Ce olefins, including both alpha olefins and internal olefins,
which may be straight or branched, aliphatic, aromatic, alkyl-
aromatic, cycloaliphatic, etc. Particularly preferred polymers
are polyisobutylenes, homopolymers and copolymers of Cz and
higher alpha olefins, atactic polypropylene,
CA 02132523 1999-04-28
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hydrogenated polymers and copolymers and terpolymers of styrene,
e.g. with isoprene and/or butadiene and hydrogenated derivatives
thereof. The polymer may be degraded in molecular weight, for
example by mastication, extrusion, oxidation or thermal
degradation, and may contain oxygen.
These viscosity modifiers are normally added to the oil
composition at a level within the range of from about 0.1 to
about loo by weight.
It may also be desirable to include an additive which serves to
stabilize the compatibility of lubricant compositions containing
relatively high levels of friction modifiers. Examples of such
additives include hydrocarbyl substituted succinic anhydrides,
more preferably polyolefin-substituted succinic anhydride wherein
the polyolefin has a number average molecular weight of from
about 500 to l0,000, more preferably from about l000 to 3000.
Preferred polyolefin substituent groups include polyisobutylene,
polybutylene-1, as well as copolymers of butene-1 with ethylene
and/or propylene. Polyisobutenyl succinic anhydride is a
preferred compatibilizer for this purpose. This ingredient may
be present in the lubricant composition at a level within the
range of about 0.1 to 5% by weight, and is preferably present at
about the same level as the total weight of friction modifier
additives.
Compositions which contain one or more of these numerous
additives are typically blended by physical admixtures into the
lube oil in amounts
CA 02132523 1999-04-28
23
effective to provide their normal attendant function.
The improved lubrication enhancement offered by compositions
within the scope of this invention can be demonstrated using what
is referred to as a Sequence VI Dynanometer Fuel Economy test,
more specifically described as the ASTM Sequence VI test method
RR: DO-2: 1204. This test is run using a 3.8 liter Buick V-6
engine equipped with cooling means to maintain a relatively
constant engine oil temperature of 150~F or 275~F, coupled to a
power absorbing dynanometer such that the engine speed and power
output can be tightly controlled.
The lubricant to be evaluated is first flushed into the engine
and aged at an oil temperature of 225 deg. F. for 32 hours. The
engine is then set to a specific speed and power output, and the
test is conducted at the temperature for the two test stages of
l50 deg. F and 275 deg. F. The engine is calibrated prior to each
candidate run, using industry standard viscosity and friction
modified reference oils. At each stage the average brake specific
consumption is calculated. After the completion of the
measurement stages, the lubricant in the engine is detergent
flushed then flushed to an SAE 30 baseline oil and the
measurements are repeated. These measurements are then used to
calculate the Equivalent Fuel Economy Improvement (EFEI) of the
candidate relative to the baseline oil.
Data reported here was collected either from the full ASTM
Sequence VI test cycle or a shortened
CA 02132523 1999-04-28
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version of the Sequence VI test, referred to as a Sequence VI
screener test, in which the test oil is aged for a reduced period
of time.
The following Examples further illustrate the invention.
Examples 1-7
A base control SAE 10W-30 formulation was prepared by mixing
about 94.5 parts by volume of mineral oil with effective amounts
of the following additive ingredients to total 100 parts:
- Polybutenyl succinic anhydride polyamine
product (borated);
- Basic Magnesium petroleum sulfonate;
- Zinc salt of mixed 2-methyl propanol, pentan-1-of
and 3-methyl butanol phosphoro dithioate;
- 0i1 soluble copper compound;
- Bis alkaryl amine;
- Deemulsifier
- Antifoamant
- Pour Point Depressant
- Viscosity Modifier
Taking this base control formulation, the following friction
modifier ingredients were added in the following amounts by
volume (V.):
Example 1: Control formulation + 0.5% V. mixed nonyl
phenol sulfides*
CA 02132523 1999-04-28
Example 2: Control formulation + 0.2o V.
N,N-bis
(2-hydroxyethyl)
tallow amine
Example 3: Control formulation + 0.5o V. mixed
nonyl phenol
sulfides*
+ 0.2o V.
N, N-bis (2-
hydroxyethyl)
tallow amine
Example 4: Control formulation + 0.2o V.
N,N-bis (2-
hydroxypropyl)
tallow amine
Example 5: Control formulation + 0.5% V. mixed
nonyl phenol
sulfides*
+ 0.2o V. N,N-bis
(2-hydroxypropyl)
tallow amine
Example 6: Control formulation + 0.2o V. borated
N,N-bis
(2-hydroxy ethyl)
tallow amine
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Example 7: Control formulation + 0.5% V. mixed
nonyl phenol
sulfides*
+ 0.2o V. borated
N,N-bis
(2-hydroxy ethyl)
tallow amine
* 67o by weight active ingredient
The Control formulation and each of the formulations of Examples
1-7 were subjected to a Sequence VI dyn~nometer fuel economy
screener test described above. The recorded EFEI test results are
as follows:
Recorded
EFEI
Result
Control 1.81
Example 1 l.74
Example 2 2.28
Example 3 2.65
Example 4 1.86
Example 5 2.l5
Example 6 2.08
Example 7 2.91
The test results show that the mixed nonyl phenol sulfides (NPS)
when added by itself at a level of 0.5o by volume to the control
base formulation actually gives rise to a reduction in the EFEI
test results as compared with the Control (1,74 vs. 1.81
respectively). When NPS is combined with N,N-bis
CA 02132523 1999-04-28
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(2-hydroxyethyl) tallow amine at respective 0.5o by volume and
0.2o by volume levels as in Example 3, an EFEI test result of
2.65 is achieved which is superior to the actual EFEI value for
this amine used alone at a 0 . 5 o by volume concentration as in
Example 2. In addition, since NPS used alone with the Control
base formulation results in a dimunition of EFEI values, the
recorded EFEI results are higher than might be expected.
Similar unexpected results are achieved when NPS is combined with
N,N-bis (2-hydroxypropyl) tallow amine as shown in Example 5 and
with boronated N,N-bis (2-hydroxyethyl)tallow amine as shown in
Example 7.
Thus the inclusion of the hydrocarbyl phenol sulfides of the
present invention, which exhibit no friction enhancing properties
on their own, into lubricating oil formulations containing an
alkoxylated amine friction modifier results in a significant and
synergistic enhancement of the lubricating properties of the oil.
