U.S. patent application number 13/124717 was filed with the patent office on 2011-09-15 for reducing high-aqueous content sludge in diesel engines.
This patent application is currently assigned to THE LUBRIZOL CORPORATION. Invention is credited to David A. Duncan, Mary Galic Raguz, Patrick E. Mosier, John J. Mullay, My Hang Truong.
Application Number | 20110224115 13/124717 |
Document ID | / |
Family ID | 41538318 |
Filed Date | 2011-09-15 |
United States Patent
Application |
20110224115 |
Kind Code |
A1 |
Mullay; John J. ; et
al. |
September 15, 2011 |
Reducing High-Aqueous Content Sludge in Diesel Engines
Abstract
Formation of high-aqueous content sludge may be reduced in a
sump lubricated diesel engine lubricated with a lubricating oil
formulation that contains at least 0.07 or 0.08 weight percent
nitrogen derived from one or more nitrogen-containing ashless
dispersants, by including in the lubricant a polyalkylene
oxide.
Inventors: |
Mullay; John J.; (Mentor,
OH) ; Truong; My Hang; (Mentor, OH) ; Duncan;
David A.; (Willoughby Hills, OH) ; Mosier; Patrick
E.; (Bay Village, OH) ; Galic Raguz; Mary;
(Mentor, OH) |
Assignee: |
THE LUBRIZOL CORPORATION
Wickliffe
OH
|
Family ID: |
41538318 |
Appl. No.: |
13/124717 |
Filed: |
October 20, 2009 |
PCT Filed: |
October 20, 2009 |
PCT NO: |
PCT/US09/61261 |
371 Date: |
May 26, 2011 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
61107475 |
Oct 22, 2008 |
|
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|
Current U.S.
Class: |
508/287 ;
508/304 |
Current CPC
Class: |
C10M 2223/042 20130101;
C10M 2219/022 20130101; C10N 2030/66 20200501; C10M 2223/045
20130101; C10M 2219/046 20130101; C10M 169/048 20130101; C10M
2209/101 20130101; C10M 2215/28 20130101; C10M 2203/1006 20130101;
C10M 2207/028 20130101; C10M 157/04 20130101; C10M 2207/026
20130101; C10M 2209/106 20130101; C10N 2030/26 20200501; C10M
2209/105 20130101; C10M 2209/103 20130101; C10M 2215/064 20130101;
C10M 2209/084 20130101; C10M 161/00 20130101; C10N 2040/252
20200501; C10M 2209/104 20130101; C10N 2030/04 20130101; C10M
2207/028 20130101; C10N 2010/04 20130101; C10M 2209/084 20130101;
C10N 2060/09 20200501; C10M 2209/101 20130101; C10N 2010/04
20130101; C10M 2209/104 20130101; C10M 2209/105 20130101; C10M
2219/046 20130101; C10N 2010/04 20130101; C10M 2223/045 20130101;
C10N 2010/04 20130101; C10M 2207/028 20130101; C10N 2010/04
20130101; C10M 2209/101 20130101; C10N 2010/04 20130101; C10M
2219/046 20130101; C10N 2010/04 20130101; C10M 2223/045 20130101;
C10N 2010/04 20130101; C10M 2209/084 20130101; C10N 2060/09
20200501 |
Class at
Publication: |
508/287 ;
508/304 |
International
Class: |
C10M 129/18 20060101
C10M129/18; C10M 133/44 20060101 C10M133/44 |
Claims
1. A method for reducing accumulation of high-aqueous content
sludge in a sump-lubricated diesel engine lubricated with a
lubricating oil formulation that contains at least one
nitrogen-containing dispersant and optionally at least one
dispersant viscosity modifier or polymeric material, wherein {the
weight percent nitrogen derived from one or more
nitrogen-containing ashless dispersants and nitrogen-containing
dispersant viscosity modifiers} plus {0.1 times the weight percent
of any aromatic carbon provided by the following aromatic
containing materials: polymeric materials, dispersants, and
dispersant viscosity modifiers} is at least 0.07, said method
comprising: including in said lubricant at least about 0.05 percent
by weight of a polyalkylene oxide.
2. The method of claim 1 wherein the aromatic containing materials
upon which the percent aromatic carbon is calculated are polymeric
materials, dispersant viscosity modifiers, and dispersants other
than Mannich dispersants.
3.-4. (canceled)
5. The method of claim 1 wherein the total of {weight percent
nitrogen derived from one or more nitrogen-containing ashless
dispersants} plus {0.1 times the weight percent aromatic carbon
provided by the recited aromatic materials} is at least 0.08 weight
percent.
6. (canceled)
7. The method of claim 1 wherein the nitrogen derived from one or
more nitrogen-containing ashless dispersants is at least 0.07
weight percent.
8. The method of claim 1 wherein the amount of the nitrogen derived
from one or more nitrogen-containing ashless dispersants is at
least 0.08 weight percent
9. The method of claim 1 wherein the diesel engine has restricted
crankcase ventilation.
10. The method of claim 1 wherein the engine contains a rocker
cover which is susceptible to formation of high-aqueous content
sludge thereon.
11. The method of claim 1 wherein the lubricating oil formulation
contains at least about 3.0 percent by weight of one or more
nitrogen-containing ashless dispersants.
12. The method of claim 1 wherein the nitrogen-containing ashless
dispersant comprises a succinimide dispersant.
13. The method of claim 1 wherein the lubricant formulation
comprises a dispersant viscosity modifier.
14. The method of claim 1 wherein the amount of the polyalkylene
oxide is about 0.1 to about 3 percent by weight.
15. (canceled)
16. The method of claim 1 wherein the polyalkylene oxide is a
polyethylene oxide, a polypropylene oxide, a polytetramethylene
oxide, or a mixed poly(ethylene-propylene) oxide, having a number
average molecular weight of about 500 to about 10,000.
17. The method of claim 1 wherein the polyalkylene oxide is a
diol.
18. The method of claim 1 wherein the lubricant comprises an oil of
lubricating viscosity and further comprises at least one additional
component selected from the group consisting of an overbased metal
detergent, a zinc dialkyldithiophosphate, and an antioxidant.
19. (canceled)
20. A lubricant composition suitable for reducing accumulation of
high-aqueous content sludge in a sump-lubricated diesel engine,
comprising: an oil of lubricating viscosity; one or more
nitrogen-containing ashless dispersants or dispersant viscosity
modifiers such that the formulation contains at least one
nitrogen-containing dispersant and optionally at least one
dispersant viscosity modifier or polymeric material, wherein {the
weight percent nitrogen derived from one or more
nitrogen-containing ashless dispersants and nitrogen-containing
dispersant viscosity modifiers} plus {0.1 times the weight percent
of any aromatic carbon provided by the following aromatic
containing materials: polymeric materials, dispersants, and
dispersant viscosity modifiers} is at least 0.07; wherein the
lubricant composition comprises a nitrogen-containing dispersant
viscosity modifier; and at least about 0.05 percent by weight of a
polyalkylene oxide.
21. The lubricant composition of claim 20 wherein the nitrogen
derived from one or more nitrogen-containing ashless dispersants is
at least 0.07 weight percent.
22. The lubricant composition of claim 20, further comprising at
least one additional additive selected from the group consisting of
detergents, metal salts of phosphorus acids, viscosity modifiers,
antioxidants, corrosion inhibitors, antiwear agents, pour point
depressants, and anti-foam agents.
23. (canceled)
24. The lubricant composition of claim 20 wherein the oil of
lubricating viscosity comprises an API Group II or Group III or
Group IV oil or a mixture thereof.
25. A method for reducing accumulation of high-aqueous content
sludge in a sump-lubricated diesel engine lubricated with a
lubricating oil formulation that contains at least 0.08 weight
percent nitrogen derived from one or more nitrogen-containing
ashless dispersants, said method comprising: including in said
lubricant at least about 0.05 percent by weight of a polyalkylene
oxide.
Description
BACKGROUND OF THE INVENTION
[0001] The disclosed technology relates to lubricant formulations
and methods for reducing or eliminating accumulation of
high-aqueous content sludge, or reducing its formation or
viscosity, in internal combustion engines.
[0002] Modern engine oil formulations, in particular for diesel
(compression ignited) engines contain a variety of additives to
impart desired lubricating performance. Recently, there has been
increasing emphasis on providing lubricants with high content of
nitrogen-containing dispersant. This development has not been
without problems, however. In certain engines, especially those
with restricted crankcase ventilation, an unusual form of sludge
has been observed accumulating in cooler portions of the engine,
such as on a rocker cover. This sludge may also be observed on
other parts of the engine. We characterize this material as
high-aqueous content sludge, as it is a sludge-like material that
appears to be a combination of lubricant oil with relatively high
amounts of water, e.g., up to 70-80 weight percent water. It is
speculated that this sludge may arise due the accumulation of water
from combustion in the lubricant oil, particularly when combustion
products are not efficiently purged from the crankcase due to
restricted ventilation. The accumulation of this sludge can lead to
restrictive flow of lubricant and corrosion of metal surfaces. It
is therefore desirable to reduce or eliminate the formation or
accumulation of this sludge.
[0003] A variety of lubricants have been used for lubricating
internal combustion engines. For instance, U.S. Pat. No. 6,642,189,
Kurihara et al., Nov. 4, 2003, discloses engine oil compositions
that may be used in motorcycle engines, automobile engines, diesel
engines for land use, and marine diesel engines. The lubricant
contains a lubricating base oil and a polymethacrylatebased
viscosity index improver. It may also contain a molybdenum
dithiocarbamate as well as one or more other engine oil additives.
Among these are detergents, dispersants, oxidation inhibitors,
friction modifiers, corrosion inhibitors, demulsifying agents such
as polyalkylene glycol-based non-ionic surfactants, metal
deactivators, and antifoamers.
[0004] U.S. Pat. No. 5,198,135, Galic et al., Mar. 30, 1993,
discloses a crankcase lubricating oil composition containing as an
antiemulsion agent an effective amount of a butylene oxide
containing polymer. Other components that may be present include a
hydrocarbon-soluble ashless dispersant, an alkali or alkaline earth
metal detergent, a zinc dialkyldithiophosphate, an antioxidant, a
viscosity modifier, a rust inhibitor, and a pour point
depressant.
[0005] U.S. Pat. No. 3,509,052, Murphy, Apr. 28, 1970, discloses
improved lubricating composition which contain a demulsifier. The
compositions reduce or eliminate the formation of sludge on the
internal metal surfaces of internal combustion engines.
Polyoxyalkylene polyols are preferred demulsifiers. The sludges
have been found in the rocker arm covers and oil-fill caps of,
particularly, smaller car engines.
SUMMARY OF THE INVENTION
[0006] The disclosed technology provides, in one embodiment, a
method for reducing accumulation of high-aqueous content sludge in
a sump-lubricated diesel engine lubricated with a lubricating oil
formulation that contains at least 0.07 or at least 0.08 weight
percent nitrogen derived from one or more nitrogencontaining
ashless dispersants, said method comprising: including in said
lubricant at least 0.05 percent by weight of a polyalkylene
oxide.
[0007] In another embodiment, the technology provides a method for
reducing accumulation of high-aqueous content sludge in a
sump-lubricated diesel engine lubricated with a lubricating oil
formulation that contains at least one nitrogen-containing
dispersant and optionally at least one dispersant viscosity
modifier or polymeric material, wherein {the weight percent
nitrogen derived from one or more nitrogen-containing ashless
dispersants and nitrogencontaining dispersant viscosity modifiers}
plus {0.1 times the weight percent of any aromatic carbon provided
by the following aromatic containing materials: polymeric
materials, dispersants, and dispersant viscosity modifiers} is at
least 0.07 (or alternatively at least 0.08), said method
comprising: including in said lubricant at least about 0.05 percent
by weight of a polyalkylene oxide.
[0008] The disclosed technology also provides a lubricant
composition suitable for reducing accumulation of high-aqueous
content sludge in a sumplubricated diesel engine, comprising: an
oil of lubricating viscosity; one or more nitrogen-containing
ashless dispersants in an amount to provide at least 0.07 or 0.08
weight percent nitrogen to the lubricant composition; and at least
0.05 percent by weight of a polyalkylene oxide.
[0009] In another embodiment the formulation contains one or more
nitrogen-containing ashless dispersants or dispersant viscosity
modifiers such that the formulation contains at least one
nitrogen-containing dispersant and optionally at least one
dispersant viscosity modifier or polymeric material, wherein {the
weight percent nitrogen derived from one or more
nitrogen-containing ashless dispersants and nitrogen-containing
dispersant viscosity modifiers} plus {0.1 times the weight percent
of any aromatic carbon provided by the following aromatic
containing materials: polymeric materials, dispersants, and
dispersant viscosity modifiers} is at least 0.07.
DETAILED DESCRIPTION OF THE INVENTION
[0010] Various preferred features and embodiments will be described
below by way of non-limiting illustration.
[0011] The technology described herein is suitable for use in a
sumplubricated diesel engine, that is, a compression ignited
engine. Diesel engines are commonly used in passenger cars, trucks,
off-road vehicles, and marine vessels. The technology is
particularly useful in those engines that are susceptible to
contamination with high aqueous content sludge, as described above.
While such sludge accumulation has been observed in a variety of
diesel engines, it is believed to be particularly significant in
engines having restricted crankcase ventilation, sometimes referred
to as "closed crankcase" or "pseudo-closed crankcase" systems. In
such systems, products of combustion such as water vapor may
accumulate and, by combination with the lubricant or portions of
the lubricant, by mechanisms that are not fully understood, may
lead to formation of high water-based sludge in relatively cooler
portions of the engine. A rocker cover, for example, may have an
ambient operating temperature of only about 25.degree. C. under
certain conditions, and thus this is a location where collection of
this sludge may be a problem.
[0012] One component of the sludge is the lubricating oil or at
least a portion or components or elements of the overall
lubricating oil composition. Lubricants for internal combustion
engines typically include a number of components that have been
selected to perform various important functions. One such
component, and normally the majority component (by which is meant a
component that is present in a major amount, that is, greater than
50 percent by weight), is an oil of lubricating viscosity.
[0013] The base oil used in the inventive lubricating oil
composition may be selected from any of the base oils in Groups I-V
as specified in the American Petroleum Institute (API) Base Oil
Interchangeability Guidelines. The five base oil groups are as
follows:
TABLE-US-00001 Base Oil Category Sulfur (%) Saturates (%) Visc.
Index Group I >0.03 and/or <90 80 to 120 Group II
.ltoreq.0.03 and .gtoreq.90 80 to 120 Group III .ltoreq.0.03 and
.gtoreq.90 >120 Group IV All polyalphaolefins (PAOs) Group V All
others not included in Groups I, II, III or IV
Groups I, II and III are mineral oil base stocks. "Gas-to-liquid"
base stocks are also generally considered Group III. The oil of
lubricating viscosity, then, can include natural or synthetic
lubricating oils and mixtures thereof. Mixture of mineral oil and
synthetic oils, particularly polyalphaolefin oils and polyester
oils, are often used in lubricants. However, the problem of high
aqueous sludge formation is sometimes more severe in some of the
more highly refined base oils, in particularly, Group II or Group
III or Group IV oils or mixtures thereof, or mixtures of oils that
contain a significant amount of Group II or Group III or Group IV
content (e.g., 50 percent by weight or more, or 80 or 90 percent or
more, of the total amount of base oil). In another embodiment the
oils may be Group II or Group III oils or such mixtures
thereof.
[0014] Natural oils include animal oils and vegetable oils (e.g.
castor oil, lard oil and other vegetable acid esters) as well as
mineral lubricating oils such as liquid petroleum oils and
solvent-treated or acid treated mineral lubricating oils of the
paraffinic, naphthenic or mixed paraffinic-naphthenic types.
Hydrotreated or hydrocracked oils are included within the scope of
useful oils of lubricating viscosity.
[0015] Oils of lubricating viscosity derived from coal or shale are
also useful. Synthetic lubricating oils include hydrocarbon oils
and halosubstituted hydrocarbon oils such as polymerized and
interpolymerized olefins and mixtures thereof, alkylbenzenes,
polyphenyl, (e.g., biphenyls, terphenyls, and alkylated
polyphenyls), alkylated diphenyl ethers and alkylated diphenyl
sulfides and their derivatives, analogs and homologues thereof.
Another suitable class of synthetic lubricating oils that can be
used comprises the esters of dicarboxylic acids and those made from
C5 to C12 monocarboxylic acids and polyols or polyol ethers.
[0016] Other synthetic lubricating oils include liquid esters of
phosphorus-containing acids, polymeric tetrahydrofurans,
silicon-based oils such as the polyalkyl-, polyaryl-, polyalkoxy-,
or polyaryloxy-siloxane oils, and silicate oils.
[0017] Hydrotreated naphthenic oils are also known and can be used.
Synthetic oils may be used, such as those produced by
Fischer-Tropsch reactions and typically may be hydroisomerised
Fischer-Tropsch hydrocarbons or waxes. In one embodiment oils may
be prepared by a Fischer-Tropsch gas-to-liquid synthetic procedure
as well as other gas-to-liquid oils.
[0018] Unrefined, refined and rerefined oils, either natural or
synthetic (as well as mixtures of two or more of any of these) of
the type disclosed hereinabove can used in the compositions of the
present invention. Unrefined oils are those obtained directly from
a natural or synthetic source without further purification
treatment. 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. Rerefined oils are obtained by
processes similar to those used to obtain refined oils applied to
refined oils which have been already used in service. Such
rerefined oils often are additionally processed by techniques
directed to removal of spent additives and oil breakdown
products.
[0019] The amount of the oil will typically be greater than 50
percent by weight of the lubricant composition when the composition
is a fully formulated lubricant. It may be equal to the balance of
the total lubricant after the dispersant, polyalkylene oxide, and
any other components are accounted for. Thus, it may be, in certain
embodiments 70 to 96 percent or 80 to 95 percent or 85 to 90
percent . In certain embodiments, the lubricant composition may be
in the form of a concentrate, suitable for subsequent dilution with
additional oil and optionally addition of further components to
prepare the fully formulated lubricant. In such cases the amount of
the oil will be proportionally less, e.g., 20 to 80 percent.
[0020] The lubricants will also contain a dispersant, in
particular, a nitrogen-containing dispersant. Dispersants are
almost universally used in lubricants for diesel engines, and the
problem of formation of high aqueous sludge is particularly
prominent in lubricants containing a relatively large amount of
nitrogen-containing dispersant.
[0021] Dispersants are well known in the field of lubricants and
include primarily what is known as ashless dispersants and
polymeric dispersants. Ashless dispersants are so-called because,
as supplied, they do not contain metal and thus do not normally
contribute to sulfated ash when added to a lubricant. However they
may, of course, interact with ambient metals once they are added to
a lubricant which includes metal-containing species. Such
dispersants are typically referred to as "ashless" even if they
have been post-treated with various agents, such as a borating
agent to provide a borated dispersant. Such dispersants are ashless
in the sense that they do not contain metal or contribute metal
content to a lubricant, even though the presence of boron may make
a small contribution to sulfated ash as measured by ASTM D 874.
Such materials would typically be encompassed within the ashless
dispersants of the present technology. Ashless dispersants are
characterized by a polar group attached to a relatively high
molecular weight hydrocarbon chain. Typical ashless dispersants
include N-substituted long chain alkenyl succinimides (succinimide
dispersants). having a variety of chemical structures including
typically
##STR00001##
where each R.sup.1 is independently an alkyl group, frequently a
polyisobutylene group with a molecular weight (M.sub.n) of 500-5000
based on the polyisobutylene precursor, and R.sup.2 are alkylene
groups, commonly ethylene (C.sub.2H.sub.4) groups, and x is 0 to 6
or above, or 1 to 5. Such molecules are commonly derived from
reaction of an alkenyl acylating agent with a polyamine such as
ethylenediamine, diethylenetriamine, triethylenetetramine,
tetraethylpentamine, and pentaethylhexamine. Also useful are
mixtures of amines, both linear and branched in various manners,
which are known commercially as amine bottoms or ethylene amine
still bottoms. They may contain mixtures of N4, N5, N6, and N7
amines.
[0022] A wide variety of linkages between the acid and amine
moieties is possible beside the simple imide structure shown above,
including a variety of amides and ammonium salts. Also, a variety
of modes of linkage of the R.sup.1 groups onto the imide structure
are possible, including various cyclic linkages. The ratio of the
carbonyl groups of the acylating agent to the nitrogen atoms of the
amine may be 1:0.5 to 1:3, and in other instances 1:1 to 1:2.75 or
1:1.5 to 1:2.5. Succinimide dispersants are more fully described in
U.S. Pat. Nos. 4,234,435 and 3,172,892 and in EP 0355895.
[0023] In certain embodiments the dispersant may also contain ester
functionality, such materials having been prepared by reacting a
hydrocarbyl acylating agent and a polyhydric aliphatic alcohol such
as glycerol, pentaerythritol, or sorbitol, in addition to an amine.
Such materials are described in more detail in U.S. Pat. No.
3,381,022.
[0024] Another class of nitrogen-containing ashless dispersant is
Mannich bases. These are materials which are formed by the
condensation of a higher molecular weight, alkyl substituted
phenol, an alkylene polyamine, and an aldehyde such as
formaldehyde. Such materials may have the general structure
##STR00002##
(including a variety of isomers and the like) where R.sup.1,
R.sup.2, and x may be as described above. These are described in
more detail in U.S. Pat. No. 3,634,515. Dispersants of the various
types described herein can also be post-treated by reaction with
any of a variety of agents. Among these are urea, thiourea,
dimercaptothiadiazoles, carbon disulfide, aldehydes, ketones,
carboxylic acids, hydrocarbon-substituted succinic anhydrides,
nitriles, epoxides, boron compounds, and phosphorus compounds.
References detailing such treatment are listed in U.S. Pat. No.
4,654,403.
[0025] In certain embodiments of the present technology, Mannich
dispersants may be present in relatively low amounts or may be
absent altogether. If Mannich dispersants are the lubricating
composition is substantially free from Mannich dispersants. This
means that, for such embodiments, any Mannich dispersants may be
present as less than 10% or less than 5% or less than 1% by weight
of the total dispersant component, e.g., 0 or 0.001 to 5% or 0.01
to 3% or 0.1 to 1% of the total dispersant component. Low-Mannich
formulations may be specified for any of a variety of reasons. In
one aspect, Mannich dispersants may not be particularly desirable
because they may not serve to effectively aid in soot formation,
which other dispersants may do. In another aspect, Mannich
dispersants would contribute both nitrogen and aromatic carbons to
the overall dispersant component. It may therefore be desirable, in
this instance, to avoid "double counting" any Mannich dispersant,
to count the nitrogen that it contributes while not counting the
aromatic carbon that it contributes, when calculating the minimum
amount of N+ aromatic C as set forth elsewhere in this
Specification.
[0026] Other dispersants include polymeric dispersant additives,
which are generally hydrocarbon-based polymers which contain polar
functionality to impart dispersancy characteristics to the polymer.
The dispersant viscosity index modifiers, also referred to as
dispersant viscosity modifiers or DVMs, can be functionalized
versions of polymers which are generally used as viscosity index
modifiers (as described below). Among the common classes of such
polymers are olefin copolymers and acrylate or methacrylate
copolymers. For example, when a small amount of a
nitrogen-containing monomer is copolymerized with alkyl
methacrylates, dispersancy properties may be incorporated into the
product. Thus, such a product may have the multiple function of
viscosity modification (as described below), pour point depressancy
and dispersancy. Such products have been referred to in the art as
dispersant-type viscosity modifiers or simply dispersant-viscosity
modifiers. Vinyl pyridine, N-vinyl pyrrolidone and
N,N'-dimethylaminoethyl methacrylate are examples of
nitrogen-containing monomers. Polyacrylates obtained from the
polymerization or copolymerization of one or more alkyl acrylates
also are useful as viscosity modifiers. Derivatives of polyacrylate
esters are well-known as dispersant viscosity index modifier
additives. Dispersant acrylate or polymethacrylate viscosity
modifiers such as Acryloid.TM. 985 or Viscoplex.TM. 6-054, from
RohMax, are particularly useful.
[0027] Functionalized olefin copolymers can also be, for instance,
interpolymers of ethylene and propylene which are grafted with an
active monomer such as maleic anhydride and then derivatized with
an alcohol or an amine, as described in U.S. Pat. No. 4,089,794.
Other such copolymers are copolymers of ethylene and propylene
which are reacted or grafted with nitrogen compounds, as described
in U.S. Pat. No. 4,068,056.
[0028] The amines useful in preparing either dispersants
(generally) or dispersant viscosity modifiers may, in certain
embodiments, be aromatic amines containing at least one, and
preferably exactly one, N--H group capable of condensing with a
carboxylic acid functionality, to form nitrogen-containing
carboxylic derivatives. Aromatic amines include those which can be
represented by the general structure NHR--Ar, where R is hydrogen
or a hydrocarbyl group and Ar is an aromatic group, including
nitrogen-containing aromatic groups and Ar groups including any of
the following structures
##STR00003##
as well as multiple non-condensed aromatic rings. In these and
related structures, R.sub.4, R.sub.5, and R.sub.6 can be
independently, among other groups disclosed herein, --H,
--C.sub.1-18 alkyl groups, --NR--Ar, --NH--Ar, --N.dbd.N--Ar,
--NH--CO--Ar, --OOC--Ar, --OOC--C.sub.1-18 alkyl, --COO--C.sub.1-18
alkyl, --OH, --O--(CH.sub.2CH.sub.2---O).sub.nC.sub.1-18 alkyl
groups, --NO.sub.2, and --O--(CH.sub.2CH.sub.2O).sub.nAr (where n
is 0 to 10).
[0029] Examples of aromatic amines include aniline, N-alkylanilines
such as N-methyl aniline, and N-butylaniline,
di-(para-methylphenyl)amine, naphthylamine, 4-aminodiphenylamine,
N,N-dimethylphenylenediamine, 4-(4-nitrophenylazo)aniline (disperse
orange 3), sulfamethazine, 4-phenoxyaniline, 3-nitroaniline,
4-aminoacetanilide 4-amino-2-hydroxy-benzoic acid phenyl ester
(phenyl amino salicylate),
N-(4-amino-5-methoxy-2-methyl-phenyl)-benzamide (fast violet B),
N-(4-amino-2,5-dimethoxy-phenyl)-benzamide (fast blue RR),
N-(4-amino-2,5-diethoxy-phenyl)-benzamide (fast blue BB),
N-(4-aminophenyl)-benzamide and 4-phenylazoaniline. Other examples
include paraethoxyaniline, para-dodecylaniline,
cyclohexyl-substituted naphthylamine, and thienyl-substituted
aniline. Examples of other suitable aromatic amines include
amino-substituted aromatic compounds and amines in which the amine
nitrogen is a part of an aromatic ring, such as 3-aminoquinoline,
5-aminoquinoline, and 8-aminoquinoline. Also included are aromatic
amines such as 2-aminobenzimidazole, which contains one secondary
amino group attached directly to the aromatic ring and a primary
amino group attached to the imidazole ring. Other amines include
N-(4-anilinophenyl)-3-aminobutanamide (i.e.,
.phi.-NH-.phi.-NH--COCH.sub.2CH(CH.sub.3)NH.sub.2). Additional
aromatic amines and related compounds are disclosed in U.S. Pat.
Nos. 4,863,623, 6,107,257, and 6,107,258; some of these include
aminocarbazoles, aminoindoles, aminopyrroles, amino-indazolinones,
mercaptotriazoles, aminophenothiazines, aminopyridines,
aminopyrazines, aminopyrimidines, aminothiadiazoles,
aminothiothiadiazoles, and aminobenzotriaozles. Other suitable
amines include 3-amino-N-(4-anilinophenyl)-N-isopropyl butanamide,
and N-(4-anilinophenyl)-3-{(3-aminopropyl)(cocoalkyl)amino}
butanamide. Other aromatic amines which can be used include various
aromatic amine dye intermediates containing multiple aromatic rings
linked by, for example, amide structures. Examples include
materials of the general structure
##STR00004##
and isomeric variations thereof, where R.sup.1 and R.sup.2 are
independently hydrogen, alkyl groups, or alkoxy groups such as
methyl, methoxy, or ethoxy. In one instance, R.sup.1 and R.sup.2
are both --OCH.sub.3 and the material is known as Fast Blue RR
[CAS#6268-05-9]. In another instance, R.sup.1 is --OCH.sub.3 and
R.sup.2 is --CH.sub.3, and the material is known as Fast Violet B
[99-21-8]. When both R.sup.1 and R.sup.2 are ethoxy, the material
is Fast Blue BB [120-00-3]. U.S. Pat. No. 5,744,429 discloses other
aromatic amine compounds, particularly aminoalkylphenothiazines.
N-aromatic substituted acid amide compounds, such as those
disclosed in U.S. Patent application 2003/0030033 A1, may also be
used for the purposes of this invention. Aromatic amines include
those in which the amine nitrogen is a substituent on an aromatic
carboxylic compound, that is, the nitrogen is not sp.sup.2
hybridized within an aromatic ring.
[0030] Certain aromatic amines are commonly used as antioxidants.
Of particular importance in that regard are alkylated
diphenylamines such as nonyldiphenylamine and dinonyldiphenylamine.
To the extent that these materials will condense with the
carboxylic functionality of the polymer chain, they are also
suitable for use within the present invention. Among such aromatic
amines are 4-phenylazoaniline, 4-aminodiphenylamine,
2-aminobenzimidazole, 3-nitroaniline, 4-(4-nitrophenylazo)aniline
(disperse orange 3),
N-(4-amino-5-methoxy-2-methyl-phenyl)-benzamide (fast violet B),
N-(4-amino-2,5-dimethoxy-phenyl)-benzamide (fast blue RR),
N-(4-amino-2,5-diethoxyphenyl)-benzamide (fast blue BB),
N-(4-amino-phenyl)-benzamide, and N,N-dimethylphenylenediamine.
[0031] The above-described aromatic amines can be used alone or in
combination with each other. They can also be used in combination
with additional, aromatic or non-aromatic, e.g., aliphatic, amines,
which, in one embodiment, comprise 1 to 8 carbon atoms. Aliphatic
monoamines include methylamine, ethylamine, propylamine and various
higher amines. Diamines or polyamines can be used to functionalize
a polymeric dispersant viscosity modifier, provided that, in
certain embodiments, they have only a single reactive amino group,
that is, a primary or secondary group. Suitable examples of such
diamines include dimethylaminopropylamine, diethylaminopropylamine,
dibutylaminopropylamine, dimethylaminoethylamine,
diethylaminoethylamine, dibutylaminoethylamine,
1-(2-aminoethyl)piperidine, 1-(2-aminoethyl)pyrrolidone,
aminoethylmorpholine, and aminopropylmorpholine.
[0032] The amount of dispersant present in the lubricant is that
amount desirable to serve as its normal function of dispersing
contaminants and maintaining cleanliness of the engine. The problem
of formation of high aqueous content sludge tends to be more
apparent however, at relatively higher dispersant levels, and it is
at such levels that the benefits of the present invention are most
evident. Thus, the present technology is typically associated with
lubricating oil formulations that, in one embodiment, contain at
least 0.07 or 0.08 weight percent of nitrogen derived from one or
more nitrogen-containing ashless dispersants. In other embodiments,
the amount of such nitrogen is at least 0.1% or at least 0.3%, and
up to 0.5 or to 0.3 percent by weight. The amount of actual
dispersant required to supply such amounts of nitrogen will, of
course, vary with the nitrogen content of the dispersant. Certain
common succinimide dispersants may contain 1.5 to 5 percent
nitrogen (oil-free basis) or 2.5 to 4.5 percent or 3 to 4 percent.
The total amount of dispersant may thus be, in certain
circumstances, at least 2.5 or 3.0 or 3.5 weight percent of the
lubricant, or at least 4.4 percent and up to 8 percent or to 7
percent or to 6 percent by weight (oil-free). The amount in a
concentrate will be correspondingly greater, e.g., 7 to 30 percent.
These amounts may be provided by one or more dispersants of similar
or different types.
[0033] The problem may also be present in the presence of
lubricants that contribute a large amount of aromatic content
associated with polymeric additives or certain dispersants. Thus,
certain polymers including those comprising vinyl aromatic monomer
units such as styrene are sometimes included in lubricants to aid
in soot dispersion, and such materials may also contribute to the
tendency to form high aqueous content sludge. Examples include
vinyl aromatic/olefin copolymers, vinyl aromatic/diene copolymers,
vinyl aromatic/maleic ester copolymers, and vinyl
aromatic/methacrylate ester copolymers. Such materials may be block
or random copolymer, and they may be (hydrogenated or
non-hydrogenated. Such polymers are typically distinguished from
dispersant viscosity modifiers. They may be viscosity modifiers,
but they are not dispersant viscosity modifiers because they do not
contain the polar functionality (of greater polarity than that
provided by an alkyl ester group) as provided by an amide or imide
group with a polyamine or with an aromatic amine with further polar
functionality. To take into account the presence of these
aromatic-containing polymers, the total amount of nitrogen may be
adjusted, as described below, if such materials are present.
[0034] Thus, in one embodiment the lubricating oil formulation
contains at least 0.07 weight percent of the total of {weight
percent nitrogen derived from one or more nitrogen-containing
ashless dispersants and nitrogen-containing dispersant viscosity
modifiers} plus {0.1 times the weight percent aromatic carbon
provided by the following aromatic containing materials: polymeric
materials, dispersants, and dispersant viscosity modifiers}, Other
values for this total include at least 0.1% or at least 0.3%, and
optionally up to 2.0 or 1.0 or 0.5 or to 0.3 percent by weight.
[0035] In another embodiment, the aromatic containing materials
upon which the percent aromatic carbon is calculated are polymeric
materials, dispersant viscosity modifiers, and dispersants other
than Mannich dispersants. In yet another embodiment, the aromatic
containing materials upon which the percent aromatic carbon is
calculated are dispersants and all dispersant viscosity modifiers.
In yet another embodiment, the aromatic containing materials upon
which the percent aromatic carbon is calculated are dispersant
viscosity modifiers and dispersants other than Mannich
dispersants.
[0036] In any of the foregoing calculations, the amount of nitrogen
derived from one or more nitrogen-containing ashless dispersants
(which may include dispersant viscosity modifiers) plus 0.1 times
the percent aromatic carbon provided by the aromatic materials as
recited in any of the embodiments above may also be at least 0.08
weight percent or at least 0.1% or at least 0.3%, and optionally up
to 2.0 or 1.0 or 0.5 or to 0.3 percent by weight.
[0037] The amount of nitrogen and aromatic carbon may be calculated
by methods known to those skilled in the art. For example, a
finished lubricant may be analyzed by first treating it with a
separation process such as membrane dialysis, to separate
relatively high molecular weight components such as dispersants,
dispersant viscosity modifiers, and polymers. The amount of
nitrogen in the separated component may be analyzed by conventional
techniques. The amount of aromatic carbon in the separated
component may be determined by conventional techniques such as
.sup.13C NMR, and if desired the amount of aromatic carbon in any
Mannich dispersants that may be present may be distinguished by
determining the amount of aromatic carbons bonded to an --OH group
and multiplying by six.
[0038] The problem of formation of high-aqueous content sludge in
such engines and such lubricants may be solved or ameliorated by
including within the lubricant one or more polyalkylene oxides.
Polyalkylene oxides are known chemicals, sometimes referred to as a
type of nonionic surfactant, having a general structure which may
be represented, in its repeating unit, by --(RO).sub.n-- where R is
an alkylene unit. When the material is terminated by OH groups it
may be referred to as a polyalkylene glycol, OH--(RO)--.sub.nH.
Polyalkylene glycols may be prepared by alkali-catalyzed
oligomerization of alkylene oxides.
[0039] Other terminating groups are possible, in which one (or
optionally both) of the terminal OH groups are replaced by another
functional group. For example, the reaction of monoalkyl ethers of
alkylene glycol with alkylene oxide may provide the monoalkyl ether
of the alkylene glycol, e.g., the monomethyl ether or the monoether
of an alkyl group of up to 30 carbon atoms. Other such materials
that may be useful include polyoxyalkylenated alkylphenol,
polyoxyalkylenated straight-chain alcohols derived from such
materials as coconut oil, tallow, or synthetic materials,
polyoxyalkylenated silicones, and polyoxyalkylenated mercaptans.
The polyoxyalkylene groups may be as described below.
[0040] The polyalkylene oxides (or, alternatively the
polyoxyalkylene groups) useful in the present technology include
those having a ratio of carbon to oxygen atoms of 2:1 or 2.25:1 or
to 2.8:1, up to 6:1 or to 4:1 or to 3.5:1. Those would include
polyethylene oxide, polypropylene oxide, and various polybutylene
oxides and mixtures thereof, that is, copolymers of different
alkylene oxides such as mixed poly (ethylene-propylene) oxides. A
material having a C:O ratio of 2.25:1 could be prepared, for
example, from a mixture of ethylene oxide and propylene oxide. In
one embodiment, polybutylene oxide may be designated as
polytetramethylene oxide or polytetrahydrofuran, which may be seen
as the product of polymerization in a 1,4 manner, that is,
poly(1,4-butanediol). Polypropylene oxide normally refers to the
1,2 addition product, although polytrimethylene oxide would be
another possible material. Thus, suitable R units include
CH.sub.2CH.sub.2, CH.sub.2CH.sub.2CH.sub.2, CH(CH.sub.3)CH.sub.2,
CH.sub.2CH(CH.sub.3), CH.sub.2CH.sub.2CH.sub.2CH.sub.2,
CH(CH.sub.3)CH.sub.2CH.sub.2, CH.sub.2CH.sub.2CH(CH.sub.3), and
mixtures and isomers thereof. If the polyalkylene oxide is prepared
so as to have an alkoxy group at one terminus (rather than a
hydroxy group), the C:O ratios for the molecule as a whole will
differ somewhat from the C:O ratio for the molecule absent the
alkoxy terminal group. The above-identified numerical ratios may be
those for the molecule as a whole, containing any terminal alkoxy
group, or they may be those for the polyalkylene oxide portion of
the molecule, absent any terminal alkoxy group. These various
values may be determined by appropriate NMR spectroscopy.
[0041] The polyalkylene oxides of the present technology may have a
number average molecular weight of 500 to 10,000 or to even 50,000,
or 800 to 5000, or 1000 to 4000, or 1500 to 4000, or 2000 to 3000.
In certain embodiments, these materials may be of a similar
molecular weight (and correspondingly similar viscosity) as similar
materials that may be used as synthetic base oils. Their viscosity
may encompass, for instance, ranges of 15-3500 or 50-2000 or
100-1500 or 150-1000 mm.sup.2/s (cSt) at 25.degree. C.; or 10-2000
or 20-1000 or 50-500 mm.sup.2/s at 40.degree. C.; or 2-400 or 2-150
mm.sup.2/s at 100.degree. C.
[0042] Polyalkylene oxides are commercially available under the
trade names PPG4000.TM., PPG2000.TM., PPG1000.TM., Tolad 7.TM.,
Terathane 2000.TM., and Terathane 1000.TM..
[0043] The amount of the polyalkylene oxide in the lubricant
formulation may typically be as low as 0.05 percent by weight in
certain embodiments, or alternatively at least 0.08 or 0.1 percent
by weight, for instance, 0.3 to 3 percent or 0.5 or 0.7 or 0.8 to 2
or to 1.5 percent by weight. The minimum amount will, of course,
depend on the effectiveness of the particular polyalkylene oxide.
For example, certain polyalkylene glycols with uncapped --OH end
groups may be useful in amount of 0.05 percent and above. For
polyalkylene glycols terminated with other functional groups,
including all or any one of those classes of materials enumerated
above, in certain embodiments the minimum amounts may also be 0.05
or 0.1 or 0.3 or 0.5 or 0.8 percent by weight. The amounts in a
concentrate will be correspondingly greater, e.g., 0.3 to 15
percent or 0.5 or 1.0 to 10 percent.
[0044] While in some embodiments the polyalkylene oxide may be
categorized as a nonionic surfactant, other surfactants may also be
present. Surfactants in general may be classified as anionic,
cationic, zwitterionic, or non-ionic. Anionic surfactants include
substances containing a long lipophilic tail bonded to a
water-soluble (hydrophilic) group at the other end, wherein the
hydrophilic group contains an anionic moiety such as a carboxylic
acid, sulfonic acid, or phenolic group, neutralized by a cation
such as an alkali metal or ammonium. The lipophilic tail is
preferably an alkyl group, typically having 8 to 21 carbon
atoms.
[0045] Cationic surfactants are similar to anionic surfactants
except that the surface-active portion of the molecule has a
positive charge. Examples of cationic surfactants include
long-chain amines and their salts, such as primary amines derived
from animal and vegetable fatty acids and tall oil and synthetic
C12-C18 primary, secondary, or tertiary amines; diamines and their
salts, quaternary ammonium salts including tetraalkylammonium salts
and imidazolinium salts derived from e.g. tallow or hydrogenated
tallow, or N-Benzyl-N-alkyldimethylammonium halides;
polyoxyethylenated long-chain amines; quaternized
polyoxyethylenated long-chain amines; and amine oxides such as
N-alkyldimethylamine oxides (which are actually zwitterionic) such
as cetyl dimethylamine oxide or stearyl dimethylamine oxide.
[0046] Zwitterionic surfactants include amino acids such as
N-alkylaminopropionic acids, N-alkyliminodipropionic acids,
imidazoline carboxylates, N-alkylbetaines, sulfobetaines, and
sultaines.
[0047] Nonionic surfactants, other than those described above as a
required component of the present technology, include materials in
which the polar functionality is not provided by an anionic or
cation group, but by a neutral polar group such as typically an
alcohol, amine, ether, ester, ketone, or amide function. Nonionic
surfactants include long-chain carboxylic acid esters, alkanolamine
condensates with fatty acids, and N-alkylpyrrolidones. Many of
these and other ionic and non-ionic surfactants are discussed in
Rosen, "Surfactants and Interfacial Phenomena," John Wiley &
Sons, pp. 7-31, 1989.
[0048] Other additives may be present, as in conventional in engine
lubricants. Such additives may include metal-containing detergents.
Metalcontaining detergents are typically overbased materials, or
overbased detergents. Overbased materials, otherwise referred to as
overbased or superbased salts, are generally homogeneous Newtonian
systems characterized by a metal content in excess of that which
would be present for neutralization according to the stoichiometry
of the metal and the particular acidic organic compound reacted
with the metal. The overbased materials are prepared by reacting an
acidic material (typically an inorganic acid or lower carboxylic
acid, such as carbon dioxide) with a mixture comprising an acidic
organic compound, a reaction medium comprising at least one inert,
organic solvent (e.g., mineral oil, naphtha, toluene, xylene) for
said acidic organic material, a stoichiometric excess of a metal
base, and a promoter such as a phenol or alcohol and optionally
ammonia. The acidic organic material will normally have a
sufficient number of carbon atoms, for instance, as a hydrocarbyl
substituent, to provide a reasonable degree of solubility in oil.
The amount of excess metal is commonly expressed in terms of metal
ratio. The term "metal ratio" is the ratio of the total equivalents
of the metal to the equivalents of the acidic organic compound. A
neutral metal salt has a metal ratio of one. A salt having 4.5
times as much metal as present in a normal salt will have metal
excess of 3.5 equivalents, or a ratio of 4.5.
[0049] Overbased detergents are often characterized by Total Base
Number (TBN). TBN is the amount of strong acid needed to neutralize
all of the overbased material's basicity, expressed as potassium
hydroxide equivalents (mg KOH per gram of sample). Detergents which
are useful in the present invention may have a TBN (oil-free basis)
of 100 to 800, and in one embodiment 150 to 750, and in another,
400 to 700.
[0050] The metal compounds useful in making the basic metal salts
are generally any Group 1 or Group 2 metal compounds (CAS version
of the Periodic Table of the Elements). The Group 1 metals of the
metal compound include Group 1a alkali metals such as sodium,
potassium, and lithium, as well as Group 1b metals such as copper.
The Group 2 metals of the metal base include the Group 2a alkaline
earth metals such as magnesium, calcium, and barium, as well as the
Group 2b metals such as zinc or cadmium.
[0051] Overbased materials are well known to those skilled in the
art. Patents describing techniques for making basic salts of
sulfonic acids, carboxylic acids, (hydrocarbyl-substituted)
phenols, phosphonic acids, and mixtures of any two or more of these
include U.S. Pat. Nos. 2,501,731; 2,616,905; 2,616,911; 2,616,925;
2,777,874; 3,256,186; 3,384,585; 3,365,396; 3,320,162; 3,318,809;
3,488,284; and 3,629,109.
[0052] In one embodiment the lubricants of the present invention
can contain an overbased sulfonate detergent. Another overbased
material which can be present is an overbased phenate detergent. In
yet another embodiment, the overbased material is an overbased
saligenin detergent. Saligenin detergents are commonly overbased
magnesium salts which are based on saligenin derivatives. A general
example of such a saligenin derivative can be represented by the
formula
##STR00005##
wherein X comprises --CHO or --CH.sub.2OH, Y comprises --CH.sub.2--
or --CH.sub.2OCH.sub.2--; M is hydrogen, ammonium, or a valence of
a metal ion such as Mg (that is to say generally, in the case of a
multivalent metal ion, one of the valences is satisfied by the
illustrated structure and other valences are satisfied by other
species such as anions, or by another instance of the same
structure), R.sup.1 is a hydrocarbyl group containing 1 to 60
carbon atoms, m is 0 to typically 10, and each p is independently
0, 1, 2, or 3, provided that at least one aromatic ring contains an
R.sup.1 substituent and that the total number of carbon atoms in
all R.sup.1 groups is at least 7. When m is 1 or greater, one of
the X groups can be hydrogen. Saligenin detergents are disclosed in
greater detail in U.S. Pat. No. 6,310,009, with special reference
to their methods of synthesis (Column 8 and Example 1) and amounts
of the various species of X and Y (Column 6).
[0053] Salixarate detergents are overbased materials that can be
represented by a substantially linear compound comprising at least
one unit of formula (I) or formula (II):
##STR00006##
each end of the compound having a terminal group of formula (III)
or (IV):
##STR00007##
such groups being linked by divalent bridging groups A, which may
be the same or different for each linkage; wherein in formulas
(I)-(IV) R.sup.3 is hydrogen or a hydrocarbyl group; R.sup.2 is
hydroxyl or a hydrocarbyl group and j is 0, 1, or 2; R.sup.6 is
hydrogen, a hydrocarbyl group, or a hetero-substituted hydrocarbyl
group; either R.sup.4 is hydroxyl and R.sup.5 and R.sup.7 are
independently either hydrogen, a hydrocarbyl group, or
hetero-substituted hydrocarbyl group, or else R.sup.5 and R.sup.7
are both hydroxyl and R.sup.4 is hydrogen, a hydrocarbyl group, or
a hetero-substituted hydrocarbyl group. At least one of R.sup.4,
R.sup.5, R.sup.6 and R.sup.7 is hydrocarbyl containing at least 8
carbon atoms. The molecules on average contain at least one of unit
(I) or (III) and at least one of unit (II) or (IV) and the ratio of
the total number of units (I) and (III) to the total number of
units of (II) and (IV) in the composition is 0.1:1 to 2:1. The
divalent bridging group "A," which may be the same or different in
each occurrence, includes --CH.sub.2-- and --CH.sub.2OCH.sub.2--.
Salixarate derivatives and methods of their preparation are
described in greater detail in U.S. Pat. No. 6,200,936 and PCT
Publication WO 01/56968. It is believed that the salixarate
derivatives have a predominantly linear, rather than macrocyclic,
structure, although both structures are intended to be encompassed
by the term "salixarate."
[0054] Glyoxylate detergents are similar overbased materials which
are based on an anionic group which, in one embodiment, may have
the structure
##STR00008##
wherein each R is independently an alkyl group containing at least
4 or 8 carbon atoms; the total number of carbon atoms in all such R
groups is at least 12 or 16 or 24. Overbased glyoxylic detergents
and their methods of preparation are disclosed in greater detail in
U.S. Pat. No. 6,310,011.
[0055] The overbased detergent can also be an overbased salicylate,
that is, a salt of an alkylsalicylic acid. The salicylic acids may
be hydrocarbyl-substituted salicylic acids wherein each substituent
contains an average of at least 8 carbon atoms per substituent and
1 to 3 substituents per molecule. Overbased salicylate detergents
and their methods of preparation are disclosed in U.S. Pat. Nos.
4,719,023 and 3,372,116.
[0056] Other overbased detergents can include overbased detergents
having a Mannich base structure, as disclosed in U.S. Pat. No.
6,569,818.
[0057] The amount of the overbased detergent, in the formulations
of the present invention, is typically at least 0.6 weight percent
on an oil-free basis. In other embodiments, it can be present in
amounts of 0.7 to 5 weight percent or 1 to 3 weight percent. Either
a single detergent or multiple detergents can be present.
[0058] The lubricant may also contain a metal salt of a phosphorus
acid. Metal salts of the formula
[(R.sup.8O)(R.sup.9O)P(.dbd.S)--S].sub.n-M
where R.sup.8 and R.sup.9 are independently hydrocarbyl groups
containing 3 to 30 carbon atoms, are readily obtainable by heating
phosphorus pentasulfide (P.sub.2S.sub.5) and an alcohol or phenol
to form an O,O-dihydrocarbyl phosphorodithioic acid. The alcohol
which reacts to provide the R.sup.8 and R.sup.9 groups may be a
mixture of alcohols, for instance, a mixture of isopropanol and
4-methyl-2-pentanol, and in some embodiments a mixture of a
secondary alcohol and a primary alcohol, such as isopropanol and
2-ethylhexanol. The resulting acid may be reacted with a basic
metal compound to form the salt. The metal M, having a valence n,
generally is aluminum, lead, tin, manganese, cobalt, nickel, zinc,
or copper, and in many cases, zinc, to form zinc
dialkyldithiophosphates. Such materials are well known and readily
available to those skilled in the art of lubricant formulation.
[0059] The lubricant may also contain a viscosity modifier, in
addition to the dispersant viscosity modifier that has been
discussed above. Viscosity modifiers, also known as viscosity index
improvers, generally are polymeric materials characterized as being
hydrocarbon-based polymers generally having number average
molecular weights between 25,000 and 500,000, e.g., between 50,000
and 200,000.
[0060] Hydrocarbon polymers can be used as viscosity index
improvers. Examples include homopolymers and copolymers of two or
more monomers of C2 to C30, e.g., C2 to C8 olefins, including both
alphaolefins and internal olefins, which may be straight or
branched, aliphatic, aromatic, alkyl-aromatic, or cycloaliphatic.
Examples include ethylene-propylene copolymers, generally referred
to as OCP's, prepared by copolymerizing ethylene and propylene by
known processes.
[0061] Hydrogenated styrene-conjugated diene copolymers are another
class of viscosity modifiers. These polymers include polymers which
are hydrogenated or partially hydrogenated homopolymers, and also
include random, tapered, star, and block interpolymers. The term
"styrene" includes various substituted styrenes. The conjugated
diene may contain four to six carbon atoms and may include, e.g.,
piperylene, 2,3-dimethyl-1,3-butadiene, chloroprene, isoprene, and
1,3-butadiene. Mixtures of such conjugated dienes are useful. The
styrene content of these copolymers may be 20% to 70% by weight or
40% to 60%, and the aliphatic conjugated diene content may be 30%
to 80% or 40% to 60%. These copolymers can be prepared by methods
well known in the art and are typically hydrogenated to remove a
substantial portion of their olefinic double bonds.
[0062] Esters obtained by copolymerizing styrene and maleic
anhydride in the presence of a free radical initiator and
thereafter esterifying the copolymer with a mixture of C4-18
alcohols also are useful as viscosity modifying additives in motor
oils. Likewise, polymethacrylates (PMA) are used as viscosity
modifiers. These materials are typically prepared from mixtures of
methacrylate monomers having different alkyl groups, which may be
either straight chain or branched chain groups containing 1 to 18
carbon atoms.
[0063] The lubricant formulation may also contain an antioxidant,
that is, an ashless or metal-free antioxidant, in contrast to the
above-described zinc dialkyldithiophosphate, which also has
antioxidant properties. Antioxidants encompass phenolic
antioxidants, which may be of the general formulas
##STR00009##
including the first, more general formula wherein R.sup.4 is an
alkyl group containing 1 to 24, or 4 to 18, carbon atoms and a is
an integer of 1 to 5 or 1 to 3, or 2. Also included are the more
specific formulas in which the phenol may be a butyl substituted
phenol containing 2 or 3 t-butyl groups. The para position of the
aromatic group may also be occupied by a hydrocarbyl group or a
group bridging two aromatic rings. In certain embodiments the para
position is occupied by an ester-containing group, such as, for
example, an antioxidant of the formula
##STR00010##
wherein R.sup.3 is a hydrocarbyl group such as an alkyl group
containing, e.g., 1 to 18 or 2 to 12 or 2 to 8 or 2 to 6 carbon
atoms; and t-alkyl can be t-butyl. Such antioxidants are described
in greater detail in U.S. Pat. No. 6,559,105.
[0064] Antioxidants also include aromatic amines based on an
aromatic ring with an HNR.sup.5 substituent, wherein R.sup.5 can
itself be an aromatic group such as a phenyl group, a naphthyl
group, or a substituted phenyl group. Each of the aromatic groups
may have one or more substituents which may independently be a
hydrocarbyl or alkyl group containing 1 to 24 or 4 to 20 or 6 to 12
carbon atoms. In one embodiment, an aromatic amine antioxidant can
comprise an alkylated diphenylamine such as nonylated diphenylamine
of the formula
##STR00011##
or a mixture of di-nonylated mono-nonylated diphenylamine.
[0065] Antioxidants also include sulfurized olefins such as mono-
or disulfides or mixtures thereof. These materials generally have
sulfide linkages having 1 to 10 sulfur atoms, for instance, 1 to 4,
or 1 or 2. Materials which can be sulfurized to form the sulfurized
organic compositions of the present invention include oils, fatty
acids and esters, olefins and polyolefins made thereof, terpenes,
or Diels-Alder adducts. Details of methods of preparing some such
sulfurized materials can be found in U.S. Pat. Nos. 3,471,404 and
4,191,659.
[0066] Molybdenum compounds can also serve as antioxidants, and
these materials can also serve in various other functions, such as
antiwear agents. The use of molybdenum and sulfur containing
compositions such as molybdenum dithiocarbamates in lubricating oil
compositions as antiwear agents and antioxidants is known. U.S.
Pat. No. 4,285,822, for instance, discloses lubricating oil
compositions containing a molybdenum and sulfur containing
composition prepared by (1) combining a polar solvent, an acidic
molybdenum compound and an oil-soluble basic nitrogen compound to
form a molybdenum-containing complex and (2) contacting the complex
with carbon disulfide to form the molybdenum and sulfur containing
composition.
[0067] Typical amounts of antioxidants will, of course, depend on
the specific antioxidant and its individual effectiveness, but
illustrative total amounts can be 0.01 to 5 percent by weight or
0.15 to 4.5 or 0.2 to 4 percent.
[0068] Yet other components may be present, including, corrosion
inhibitors, extreme pressure and anti-wear agents. These materials
include chlorinated aliphatic hydrocarbons; boron-containing
compounds including borate esters; and molybdenum compounds.
[0069] Among the components that may also be present are various
derivatives of hydroxycarboxylic acids, which may variously impart
as one or more of friction modification, anti-wear, anti-corrosion,
demulsification, and antioxidant activity. Examples suitable
hydroxycarboxylic acids from which a derivative may be prepared
include citric acid, tartaric acid, malic acid (or hydroxysuccinic
acid), mandelic acid, lactic acid, glycolic acid, hydroxy-propionic
acid, hydroxyglutaric acid, and mixtures thereof. In another
embodiment the derivative may be prepared from tartaric acid,
citric acid, hydroxy-succinic acid, dihydroxy mono-acids,
mono-hydroxy diacids, or mixtures thereof. In one embodiment the
derivative includes a compound derived more particularly from
tartaric acid.
[0070] In certain embodiments the derivative of hydroxycarboxylic
acid may be an imide, di-ester, di-amide, or ester-amide derivative
of tartaric acid, citric acid, or mixtures thereof. In one
embodiment the derivative of hydroxycarboxylic acid may be an
imide, di-ester, di-amide, or ester-amide derivative of tartaric
acid. The derivatives may also be ester-imides or imide-amides
(applicable for tri-acids and higher, such as citric acid) or
di-imides (applicable for tetra-acids and higher).
[0071] Particular examples of such materials include tartrate
diester of a C.sub.6 to C.sub.15 alcohol, butyl citrate, and
isotridecyloxy-propyl tartrimides. These and other such materials
and their methods of preparation are more fully disclosed in PCT
Publication WO 2006/044411 and in U.S. provisional application Ser.
No. 61/037,837, filed Mar. 19, 2008.
[0072] Others compounds that may be present in the present
formulations include pour point depressants, as described in page 8
of "Lubricant Additives" by C. V. Smalheer and R. Kennedy Smith
(Lesius-Hiles Company Publishers, Cleveland, Ohio, 1967); also
anti-foam agents such as silicones or organic polymers, described
in "Foam Control Agents", by Henry T. Kerner (Noyes Data
Corporation, 1976), pages 125-162. Some of the additives described
herein are also described in greater detail in U.S. Pat. No.
4,582,618 (column 14, line 52 through column 17, line 16,
inclusive).
[0073] As used herein, the term "hydrocarbyl substituent" or
"hydrocarbyl group" is used in its ordinary sense, which is
well-known to those skilled in the art. Specifically, it refers to
a group having a carbon atom directly attached to the remainder of
the molecule and having predominantly hydrocarbon character.
Examples of hydrocarbyl groups include:
[0074] 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 a ring);
[0075] substituted hydrocarbon substituents, that is, substituents
containing non-hydrocarbon groups which, in the context of this
invention, do not alter the predominantly hydrocarbon nature of the
substituent (e.g., halo (especially chloro and fluoro), hydroxy,
alkoxy, mercapto, alkylmercapto, nitro, nitroso, and sulfoxy);
[0076] hetero substituents, that is, substituents which, while
having a predominantly hydrocarbon character, in the context of
this invention, contain other than carbon in a ring or chain
otherwise composed of carbon atoms and encompass substituents as
pyridyl, furyl, thienyl and imidazolyl. Heteroatoms include sulfur,
oxygen, and nitrogen. In general, no more than two, preferably no
more than one, non-hydrocarbon substituent will be present for
every ten carbon atoms in the hydrocarbyl group; typically, there
will be no non-hydrocarbon substituents in the hydrocarbyl
group.
[0077] It is known that some of the materials described above may
interact in the final formulation, so that the components of the
final formulation may be different from those that are initially
added. For instance, metal ions (of, e.g., a detergent) can migrate
to other acidic or anionic sites of other molecules. The products
formed thereby, including the products formed upon employing the
composition of the present invention in its intended use, may not
be susceptible of easy description. Nevertheless, all such
modifications and reaction products are included within the scope
of the present invention; the present invention encompasses the
composition prepared by admixing the components described
above.
Examples
[0078] The reduction of accumulation of high-aqueous content sludge
is modeled by the reduction of its viscosity, water content, and
problems derived therefrom. This may be accomplished by a bench
test which involves combining 40 g deionized water and 10 g test
lubricant oil in a 400 mL beaker. The water is added to the oil,
which is stirred with a magnetic stir bar (setting at 3.5 units out
of 10), over the course of about 4 minutes using a peristaltic
pump. After the addition is complete, stirring is discontinued, the
blend is allowed to sit for 10 minutes, and the blend is then
poured into a 110 mL (4 oz) glass jar. When a high-aqueous content
sludge forms, it is detected by observing a layer of such material
in the jar, above a water layer, with sometimes a separate oil
layer on the top. A sample of the high-aqueous sludge is removed
and its viscosity at 25.degree. C. is measured as well as its water
content. Reduced water content and reduced viscosity appear to be
roughly correlated, indicating that in desirable situations (a)
little or less water is entrapped within the oil and (b) any sludge
which may be formed, being less viscous, more readily drains from
surfaces back into the oil sump or to hotter surfaces where it is
dissipated or degraded.
[0079] The lubricant formulation to be tested as the baseline is
described in the table below.
TABLE-US-00002 amount, Component % Base oil, API Group III 69.5
Succinimide dispersant(s) (including about 48% diluent oil) 10.7
Viscosity modifier(s) (including. about 94% diluent oil) 9.0
Dispersant viscosity modifier(s) 4.0 (including. about 87% diluent
oil) Overbased Ca sulfonate detergent(s) (incl. about 47% diluent
oil) 1.39 Overbased Ca salixarate detergent(s) 0.55 (incl. about
51% diluent oil) Overbased Ca phenate detergent(s) (incl. about 36%
diluent oil) 1.04 Zinc dialkyldithiophosphate(s) (including about
10% diluent oil) 1.10 Mixed antioxidants: amine, sulfurized olefin,
and phenolic 1.79 Pour point depressant(s) (including about 54%
diluent oil) 0.2 Other minor components plus additional diluent oil
0.75
The baseline lubricant has a TBN (calculated) of 35 and sulfated
ash (ASTM D 874) of 0.98.
[0080] The above base fluid, alone and with the additives
identified in the following table, is tested using the above
described methodology. Results are shown in the table below.
TABLE-US-00003 Sludge Vis- Amount % cosity Ex Additive % H.sub.2O
(mPa-s) 1* None .sup. 73.sup.a 2277 2 Polypropylene glycol, M.sub.n
4000 0.1 32 437 3 Polypropylene glycol, M.sub.n 4000 1 7 245 4
Polypropylene glycol, M.sub.n 2000 1 53 616 5 Polypropylene glycol,
M.sub.n 2000 2 2 261 6 Polypropylene glycol, M.sub.n 1000 1 58 1565
7 Polypropylene glycol, M.sub.n 1000 2 12 299 8 Commercial material
believed to be 1 40 869 mixed polyethylene oxide/propylene oxide,
M.sub.w 4000, 35% propylene oxide units at ends of polymer chains 9
Commercial material (Tolad 7 .TM.) 1 8 286 believed to be ethylene
oxide/ propylene oxide copolymer, M.sub.w 5000-10,000 (50-60%
active ingredient) 10 Ethylene oxide/propylene oxide 1 56 1401
copolymer, M.sub.w 5000 (90-100% active ingred.) 11 Same as 10,
different source 2 16 321 12 Ethylene oxide/propylene oxide 1 43
358 copolymer, M.sub.w 2000 (90-100% active ingred.) 13 Same as 12
2 1 250 14 Polytetramethyleneether glycol, 1 55 860 M.sub.n 2000 15
Polytetramethyleneether glycol, 2 23 364 M.sub.n 2000 16
Polytetramethyleneether glycol, 0.1 25 422 M.sub.n 1000 17
Polytetramethyleneether glycol, 1 31 372 M.sub.n 1000 18
Polytetramethyleneether glycol, 2 11 318 M.sub.n 1000 *comparative
.sup.aaverage of 3 measurements: 78, 71, 69
For comparison, two commercial demulsifiers of unknown composition,
Tolad 370.TM. and Tolad 9330.TM., are generally less effective at
1% nominal concentration, providing water content of 62% and 72%,
respectively, and viscosity of 1155 and 1857 mPa-s, respectively.
For reference, two other commercial materials, believed to contain
ethoxylated alkyl phenol at very low concentrations (perhaps
5-10%), provide only slight benefit at 1% nominal concentration:
water content 57 and 60 percent, respectively and viscosity 2210
and 1941 mPa-s, respectively.
[0081] Each of the documents referred to above is incorporated
herein by reference. The mention of any document is not an
admission that such document qualifies as prior art or constitutes
the general knowledge of the skilled person in any jurisdiction.
Except in the Examples, or where otherwise explicitly indicated,
all numerical quantities in this description specifying amounts of
materials, reaction conditions, molecular weights, number of carbon
atoms, and the like, are to be understood as modified by the word
"about." Unless otherwise indicated, each chemical or composition
referred to herein should be interpreted as being a commercial
grade material which may contain the isomers, by-products,
derivatives, and other such materials which are normally understood
to be present in the commercial grade. However, the amount of each
chemical component is presented exclusive of any solvent or diluent
oil, which may be customarily present in the commercial material,
unless otherwise indicated. It is to be understood that the upper
and lower amount, range, and ratio limits set forth herein may be
independently combined. Similarly, the ranges and amounts for each
element of the invention can be used together with ranges or
amounts for any of the other elements. As used herein, the
expression "consisting essentially of" permits the inclusion of
substances that do not materially affect the basic and novel
characteristics of the composition under consideration.
* * * * *