U.S. patent application number 11/960949 was filed with the patent office on 2008-07-31 for lubricant composition for bio-diesel fuel engine applications.
Invention is credited to Cathy C. DEVLIN, Charles A. PASSUT.
Application Number | 20080182768 11/960949 |
Document ID | / |
Family ID | 39186510 |
Filed Date | 2008-07-31 |
United States Patent
Application |
20080182768 |
Kind Code |
A1 |
DEVLIN; Cathy C. ; et
al. |
July 31, 2008 |
LUBRICANT COMPOSITION FOR BIO-DIESEL FUEL ENGINE APPLICATIONS
Abstract
A diesel engine operating on a fuel containing from about 5 to
about 100 wt. % bio-diesel components and being lubricated with a
lubricating oil composition including a major amount of oil of
lubricating viscosity, and a minor amount of at least one highly
grafted, multi-functional olefin copolymer. The olefin copolymer is
made by reacting an acylating agent with an olefin copolymer having
a number average molecular weight greater than about 1,000 in the
present of a free radical initiator to provide an acylated olefin
copolymer having a degree of grafting (DOG) of the acylating agent
on the olefin copolymer of at least 0.5 wt. %, and reacting the
acylated olefin copolymer with an amine to provide the highly
grafted, multi-functional olefin copolymer. As used, the highly
grafted, multi-functional olefin copolymer is effective to reduce a
viscosity increase in the lubricating oil composition for the
engine.
Inventors: |
DEVLIN; Cathy C.; (Richmond,
VA) ; PASSUT; Charles A.; (Midlothian, VA) |
Correspondence
Address: |
AFTON CHEMICAL CORPORATION;LUEDEKA, NEELY & GRAHAM, PC
P.O. BOX 1871
KNOXVILLE
TN
37901
US
|
Family ID: |
39186510 |
Appl. No.: |
11/960949 |
Filed: |
December 20, 2007 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
|
60887539 |
Jan 31, 2007 |
|
|
|
Current U.S.
Class: |
508/287 ;
123/196R; 508/502; 508/505; 508/568; 508/577 |
Current CPC
Class: |
C10N 2030/041 20200501;
C10M 2207/283 20130101; C10N 2060/09 20200501; C10M 2217/06
20130101; C10M 2205/024 20130101; C10N 2010/04 20130101; C10N
2030/56 20200501; C10M 159/005 20130101; C10M 2207/262 20130101;
C10N 2010/12 20130101; C10M 2215/28 20130101; C08F 8/32 20130101;
C10N 2030/78 20200501; C10N 2030/02 20130101; C10N 2010/08
20130101; C10M 2219/046 20130101; C10M 2207/028 20130101; C10M
2205/028 20130101; C10N 2040/253 20200501; C10N 2040/252 20200501;
C10M 2205/022 20130101; C10M 149/02 20130101; C08F 8/32 20130101;
C08F 10/00 20130101; C10M 2219/046 20130101; C10N 2010/04 20130101;
C10M 2207/028 20130101; C10N 2010/04 20130101; C10M 2207/262
20130101; C10N 2010/04 20130101; C10M 2219/046 20130101; C10N
2010/04 20130101; C10M 2207/028 20130101; C10N 2010/04 20130101;
C10M 2207/262 20130101; C10N 2010/04 20130101 |
Class at
Publication: |
508/287 ;
123/196.R; 508/505; 508/577; 508/502; 508/568 |
International
Class: |
C10M 169/00 20060101
C10M169/00; F01M 11/00 20060101 F01M011/00 |
Claims
1. A diesel engine operating on a fuel containing from about 5 to
about 100 wt. % bio-diesel components and being lubricated with a
lubricating oil composition comprising a major amount of oil of
lubricating viscosity, and a minor amount of at least one highly
grafted, multi-functional olefin copolymer made by reacting an
acylating agent with an olefin copolymer having a number average
molecular weight greater than about 1,000 in the presence of a free
radical initiator to provide an acylated olefin copolymer having a
degree of grafting (DOG) of the acylating agent on the olefin
copolymer of at least 0.5 wt. %, and reacting the acylated olefin
copolymer with an amine to provide the highly grafted,
multi-functional olefin copolymer, wherein the highly grafted,
multi-functional olefin copolymer is effective to reduce a
viscosity increase in the lubricating oil composition for the
engine to less than or equal to a viscosity increase in a
lubrication oil composition for an engine operating on a fuel
devoid of the bio-diesel components.
2. The diesel engine of claim 1, wherein the oil of lubricating
viscosity has a saturates content of at least 75 wt. %, and the
olefin copolymer comprises a copolymer of ethylene and one or more
C.sub.3-C.sub.23 alpha olefins.
3. The diesel engine of claim 1, wherein the lubricating oil
composition further comprises a dispersant/inhibitor package.
4. The diesel engine of claim 3, wherein the dispersant/inhibitor
package comprises a dispersant, a metal-containing detergent, an
antiwear agent, an antioxidant, and a friction modifier.
5. The diesel engine of claim 4, wherein the detergent is selected
from the group consisting of neutral and overbased calcium
sulfonate, overbased magnesium sulfonate, calcium phenate, calcium
salicylate, magnesium salicylate, magnesium phenate, and mixtures
thereof.
6. The diesel engine of claim 4, wherein the dispersant comprises
one or more polyalkenyl succinimide dispersants.
7. The diesel engine of claim 4, wherein the friction modifier is
selected from the group consisting of non-metal containing organic
friction modifiers, organometallic friction modifiers, and mixtures
thereof.
8. The diesel engine of claim 7, wherein the organometallic
friction modifier is selected from the group consisting of oil
soluble organo-titanium, oil soluble organo-molybdenum compounds,
and oil soluble organo-tungsten compounds.
9. The diesel engine of claim 7, wherein the non-metal containing
friction modifier is selected from the group consisting of glycerol
monooleate, and nitrogen containing friction modifiers.
10. The diesel engine of claim 1, wherein the acylated olefin
copolymer has a degree of grafting (DOG) ranging from about 1.5 to
about 2.5 wt. %.
11. The diesel engine of claim 1, wherein the diesel engine is
equipped with an exhaust gas recirculation system.
12. A method for reducing a viscosity increase in a lubricating oil
composition for a diesel engine operating on a fuel containing from
about 5 to about 100 wt. % bio-diesel, comprising: lubricating the
engine with a lubricant composition comprising a major amount of
oil of lubricating viscosity, and a minor amount of at least one
highly grafted, multi-functional olefin copolymer made by reacting
an acylating agent with an olefin copolymer having a number average
molecular weight greater than about 1,000 in the present of a free
radical initiator to provide an acylated olefin copolymer having a
degree of grafting (DOG) of the acylating agent on the olefin
copolymer of at least 0.5 wt. %, and reacting the acylated olefin
copolymer with an amine to provide the highly grafted,
multi-functional olefin copolymer, and operating the engine to
provide a viscosity increase as determined by a T-11 engine test in
the lubricating oil composition that is less than a viscosity
increase in the lubricating oil for an engine operating on a diesel
fuel devoid of bio-diesel components.
13. The method of claim 12, wherein the diesel engine comprises a
diesel engine having an exhaust gas recirculation system.
14. The method of claim 12, wherein the lubricant composition has a
saturates content of at least 75 wt. %, and the olefin copolymer
comprises a copolymer of ethylene and one or more C.sub.3-C.sub.23
alpha olefins.
15. The method of claim 14, wherein the lubricant composition
further comprises a dispersant/inhibitor package.
16. The method of claim 15, wherein the dispersant/inhibitor
package comprises a dispersant, a metal-containing detergent, an
antiwear agent, an antioxidant, and a friction modifier.
17. The method of claim 16, wherein the detergent is selected from
the group consisting of neutral and overbased calcium sulfonate,
overbased magnesium sulfonate, calcium phenate, calcium salicylate,
magnesium salicylate, magnesium phenate, and mixtures thereof.
18. The method of claim 16, wherein the dispersant comprises one or
more polyalkenyl succinimide dispersants.
19. The method of claim 16, wherein the friction modifier is
selected from the group consisting of non-metal containing organic
friction modifiers, organometallic friction modifiers, and mixtures
thereof.
20. The method of claim 19, wherein the organometallic friction
modifier is selected from the group consisting of oil soluble
organo-titanium, oil soluble organo-molybdenum compounds, and oil
soluble organo-tungsten compounds.
21. The method of claim 19, wherein the non-metal containing
friction modifier is selected from the group consisting of glycerol
monooleate, and nitrogen-containing friction modifiers.
22. The method of claim 12, wherein the acylated olefin copolymer
has a degree of grafting (DOG) ranging from about 1.5 to about 2.5
wt. %.
Description
RELATED APPLICATION
[0001] This application claims priority to provisional application
No. 60/887,539, filed Jan. 31, 2007.
TECHNICAL FIELD
[0002] The disclosure relates to bio-diesel fuel engine lubrication
and to improved lubricant compositions for bio-diesel fuel engine
applications that provide improved properties.
BACKGROUND AND SUMMARY
[0003] Emission requirements for all vehicles have become
increasingly more stringent. For instance, diesel engine design
changes required to meet emission requirements have led to
increased levels of soot in engine lubricants. An increased level
of soot may cause increased wear when oils are not properly
formulated due to an increase in oil viscosity and/or inability of
the oil to disperse particles that may cause engine wear. In
particular, with the arrival of new exhaust gas recirculation or
recycle (hereinafter "EGR") cooled engines including cooled EGR
engines, a problem has developed in the ability of the conventional
lubricating oils to handle the resulting increased soot loading.
Increases in the soot loading may also result from the use of lower
grade fuels such as bio-diesel fuels that are more bio-degradable
but often include more soot producing and oil thickening
components.
[0004] Certain diesel engines with cooled EGR may exhibit
undesirable oil thickening because of the way soot and blowby
generated in the engine contaminate the engine oil. Increasing the
treat rate of standard dispersants in the lubricating oils may not
adequately solve the problems caused by an increased use of
bio-diesel fuels in the engines. Accordingly, there continues to be
a need for lubricant formulations that are more compatible with
newer heavy duty diesel fuels, particularly, fuels containing
increased levels of bio-fuel components.
[0005] In accordance with a first exemplary embodiment, the
disclosure provides a diesel engine operating on a fuel containing
from about 5 to about 100 percent by weight bio-diesel fuel. The
engine is lubricated with a major amount of oil of lubricating
viscosity, and a minor amount of at least one highly grafted,
multi-functional olefin copolymer made by reacting an acylating
agent with an olefin copolymer having a number average molecular
weight greater than about 1,000 in the present of a free radical
initiator to provide an acylated olefin copolymer having a degree
of grafting (DOG) of the acylating agent on the olefin copolymer of
at least 0.5 wt. %, and reacting the acylated olefin copolymer with
an amine to provide the highly grafted, multi-functional olefin
copolymer. In the engine, the highly grafted, multi-functional
olefin copolymer is effective to reduce a viscosity increase in the
lubricating oil composition for the engine to less than or equal to
a viscosity increase in a lubrication oil composition for an engine
operating on a fuel devoid of the bio-diesel components.
[0006] In another exemplary embodiment, the disclosure provides
method for reducing a viscosity increase in a lubricating oil
composition for a diesel engine operating on a fuel containing from
about 5 to about 100 wt. % bio-diesel. The engine is lubricated
with a lubricant composition containing a major amount of oil of
lubricating viscosity, and a minor amount of at least one highly
grafted, multi-functional olefin copolymer made by reacting an
acylating agent with an olefin copolymer having a number average
molecular weight greater than about 1,000 in the present of a free
radical initiator to provide an acylated olefin copolymer having a
degree of grafting (DOG) of the acylating agent on the olefin
copolymer of at least 0.5 wt. %, and reacting the acylated olefin
copolymer with an amine to provide the highly grafted,
multi-functional olefin copolymer. The engine is operated to
provide a viscosity increase as determined by a T-11 engine test in
the lubricating oil composition that is less than a viscosity
increase in the lubricating oil for an engine operating on a diesel
fuel devoid of bio-diesel components.
[0007] Accordingly, a primary advantage of the exemplary
embodiments may be an increased in oil change intervals due to a
lower viscosity increase in the lubricating oil for an engine
operating on a fuel containing bio-diesel components.
BRIEF DESCRIPTION OF THE DRAWINGS
[0008] FIG. 1 is a graphical comparison of viscosity versus soot
loading for lubricants in engines operating on a diesel fuel
containing bio-diesel components and a diesel fuel devoid of
biodiesel components.
DETAILED DESCRIPTION OF EXEMPLARY EMBODIMENTS
[0009] As described in more detail below, a lubricating oil for a
diesel engine operating on a fuel containing bio-diesel components
may be synergistically improved by the addition of a particular
highly grafted, multi-functional olefin copolymer. More
particularly, a lubricating oil containing a conventional
dispersant/inhibitor (DI) package may be significantly improved for
use in certain engines operating on bio-diesel fuels by
incorporating the highly grafted olefin copolymer as a
dispersant/viscosity index improver. Such lubricating oil
compositions, as described more fully herein, may be particularly
useful for lubricating internal combustion engines (e.g., heavy
duty diesel engines, and light duty diesel engines, including
diesel engines equipped with exhaust gas recirculator (EGR)
systems). Lubricant compositions containing the highly grafted,
multi-functional olefin copolymer may have improved soot dispersing
(deagglomeration), deposit control, and boundary film formation
performance, as well as improved viscosity performance thereby
improving the wear protection for the engine.
[0010] In one embodiment, the highly grafted, multi-functional
olefin copolymer product may be added to lubricating compositions
in an amount sufficient to reduce the amount of oil thickening of
the lubricating oil due to soot content, especially in exhaust gas
recirculation (EGR) equipped diesel engines.
[0011] As described more fully in U.S. Pat. No. 7,253,231, the
highly grafted, multi-functional olefin copolymer is provided as
the reaction product of a previously dehydrated copolymer substrate
that is derived from a polymer of ethylene and one or more C.sub.3
to C.sub.23 alpha-olefins. The copolymer is acylated with an
acylating agent and is further reacted with an amine to provide the
multi-functional product. The foregoing multi-functional product
may be used in lubrication compositions to provide one or more
functions including as a viscosity index (VI) modifier, dispersant,
film formation improver, deposit controller, as well as other
functions.
[0012] The polymer substrate starting material for multi-functional
olefin copolymer is derived from copolymers of ethylene and one or
more C.sub.3 to C.sub.23 alpha-olefins. Copolymers of ethylene and
propylene are suitably used to make the copolymer. "Copolymers"
herein may include without limitation blends or reacted products of
ethylene and one or more C.sub.3 to C.sub.23 alpha-olefins, and
additionally optionally other dienes or polyenes. Thus,
"copolymers" herein also includes terpolymers, and other higher
forms. Other alpha-olefins suitable in place of propylene to form
the copolymer or to be used in combination with ethylene and
propylene to form a terpolymer include 1-butene, 1-pentene,
1-hexene, 1-octene and styrene; .alpha,.omega.-diolefins such as
1,5-hexadiene, 1,6-heptadiene, 1,7-octadiene; branched chain
alpha-olefins such as 4-methylbutene-1,5-methylpentene-1 and
6-methylheptene-1; and mixtures thereof.
[0013] Methods for making the copolymers described above are
described, e.g., in U.S. Pat. Nos. 4,863,623, 5,075,383, and
6,107,257, which descriptions are incorporated herein by reference.
The polymer substrate also may be commercially obtained having the
properties indicated herein.
[0014] More complex polymer substrates, often designated as
interpolymers, also may be used as the olefin polymer starting
material, which may be prepared using a third component. The third
component generally used to prepare an interpolymer substrate is a
polyene monomer selected from nonconjugated dienes and trienes.
The-non-conjugated diene component is one having from 5 to 14
carbon atoms in the chain. For example, the diene monomer may be
characterized by the presence of a vinyl group in its structure and
can include cyclic and bicyclo compounds. Representative dienes
include 1,4-hexadiene, 1,4-cyclohexadiene, dicyclopentadiene,
5-ethylidene-2-norbornene, vinylnorbornene,
5-methylene-2-norborene, 1,5-heptadiene, and 1,6-octadiene. A
mixture of more than one diene may be used in the preparation of
the interpolymer. A suitable nonconjugated diene for preparing a
terpolymer or interpolymer substrate is 1,4-hexadiene.
[0015] The triene component may have at least two nonconjugated
double bonds, and up to about 30 carbon atoms in the chain. Typical
trienes that may be used to prepare the interpolymer of the
disclosure are
1-isopropylidene-3.alpha.,4,7,7.alpha.-tetrahydroindene,
1-isopropylidenedicyclopentadiene, dihydro-isodicyclopentadiene,
and 2-(2-methylene-4-methyl-3-pentenyl)
[2.2.1]bicyclo-5-heptene.
[0016] Ethylene-propylene or higher alpha-olefin copolymers may
consist of from about 15 to 80 mole percent ethylene and from about
85 to 20 mole percent C.sub.3 to C.sub.23 alpha-olefin with the
mole ratios in one embodiment being from about 35 to 75 mole
percent ethylene and from about 65 to 25 mole percent of a C.sub.3
to C.sub.23 alpha-olefin, with the proportions in another
embodiment being from 50 to 70 mole percent ethylene and 50 to 30
mole percent C.sub.3 to C.sub.23 alpha-olefin, and the proportions
in yet another embodiment being from 55 to 65 mole percent ethylene
and 45 to 35 mole percent C.sub.3 to C.sub.23 alpha-olefin.
[0017] Terpolymer variations of the foregoing polymers may contain
from about 0 to 10 mole percent of a nonconjugated diene or triene.
Other termonomer levels are less than 1 mole percent.
[0018] The starting polymer that is acylated is desirably an
oil-soluble, linear or branched polymer having a number average
molecular weight from about 1,000 to 500,000, and for example a
number average molecular weight of 50,000 to 250,000, as determined
by gel permeation chromatography and universal calibration
standardization.
[0019] The term "polymer" is used generically to encompass ethylene
copolymers, terpolymers or interpolymers. Such materials may
contain amounts of other olefinic monomers so long as the basic
characteristics of the polymers are not materially changed.
[0020] The polymerization reaction used to form an ethylene olefin
copolymer may be conducted in the presence of a conventional
Ziegler-Natta or metallocene catalyst system. The polymerization
medium is not specific and may include solution, slurry, or gas
phase processes, as known to those skilled in the art. When
solution polymerization is employed, the solvent may be any
suitable inert hydrocarbon solvent that is liquid under reaction
conditions for polymerization of alpha-olefins; examples of
satisfactory hydrocarbon solvents include straight chain paraffins
having from 5 to 8 carbon atoms, with hexane being preferred.
Aromatic hydrocarbons, for example, aromatic hydrocarbon having a
single benzene nucleus, such as benzene, toluene and the like; and
saturated cyclic hydrocarbons having boiling point ranges
approximating those of the straight chain paraffinic hydrocarbons
and aromatic hydrocarbons described above are particularly
suitable. The solvent selected may be a mixture of one or more of
the foregoing hydrocarbons. When slurry polymerization is employed,
the liquid phase for polymerization is preferably liquid propylene.
It is desirable that the polymerization medium be free of
substances that will interfere with the catalyst components.
[0021] The polymer described above, i.e., the olefin polymer
component, may be conveniently obtained in the form of ground or
pelletized polymer. The olefin polymer may also be supplied as
either a pre-mixed bale or a pre-mixed friable chopped agglomerate
form.
[0022] In one embodiment, ground polymer bales or other forms of
the olefin copolymer are fed to an extruder e.g., a single or twin
screw extruder, or a Banbury or other mixer having the capability
of heating and effecting the desired level of mechanical work
(agitation) on the polymer substrate for the dehydration step. A
nitrogen blanket can be maintained at the feed section of the
extruder to minimize the introduction of air.
[0023] The olefin copolymer is initially heated before being
admixed with any other reactants in the extruder or other mixer
with venting to eliminate moisture content in the feed material.
The dried olefin copolymer is in one embodiment then fed into
another extruder section or separate extruder in series for
conducting the grafting reaction.
[0024] A graft monomer is next grafted onto the polymer backbone of
the polymer olefin copolymer to form an acylated
ethylene-alphaolefin polymer.
[0025] Suitable graft monomers include ethylenically unsaturated
carboxylic acid materials, such as unsaturated dicarboxylic acid
anhydrides and their corresponding acids. Examples of these graft
monomers are set forth, for example, in U.S. Pat. No. 5,837,773,
which descriptions are incorporated herein by reference. Carboxylic
reactants which are suitable for grafting onto the
ethylene-alphaolefin interpolymers contain at least one ethylenic
bond and at least one carboxylic acid or its anhydride groups or a
polar group which is convertible into said carboxyl groups by
oxidation or hydrolysis. The carboxylic reactants are selected from
the group consisting of acrylic, methacrylic, cinnamic, crotonic,
maleic, fumaric and itaconic reactants or a mixture of two or more
of these. In the case of unsaturated ethylene copolymers or
terpolymers, itaconic acid or its anhydride is useful due to its
reduced tendency to form a cross-linked structure during the
free-radical grafting process.
[0026] The ethylenically unsaturated carboxylic acid materials
typically may provide one or two carboxylic groups per mole of
reactant to the grafted copolymer. That is, methyl methacrylate may
provide one carboxylic group per molecule to the grafted copolymer
while maleic anhydride may provide two carboxylic groups per
molecule to the grafted copolymer.
[0027] The grafting reaction to form the acylated olefin copolymers
is generally carried out with the aid of a free-radical initiator
either in bulk or in solution. The grafting may be carried out in
the presence of a free-radical initiator dissolved in oil. The use
of a free-radical initiator dissolved in oil results in a more
homogeneous distribution of acylated groups over the olefin
copolymer molecules.
[0028] The free-radical initiators which may be used to graft the
ethylenically unsaturated carboxylic acid material to the polymer
backbone include peroxides, hydroperoxides, peresters, and also azo
compounds and preferably those which have a boiling point greater
than 100.degree. C. and decompose thermally within the grafting
temperature range to provide free radicals. Representatives of
these free-radical initiators are azobutyronitrile, dicumyl
peroxide, 2,5-dimethylhexane-2,5-bis-tertiarybutyl peroxide and
2,5-dimethylhex-3-yne-2,5-bis-tertiary-butyl peroxide. The
initiator may be used in an amount ranging from about 0.005% to
about 1% by weight based on the weight of the reaction mixture.
[0029] To perform the grafting reaction as a solvent-free or
essentially solvent-free bulk process, the graft monomer and olefin
copolymer are in one embodiment fed to an extruder, e.g., a single
or twin screw extruder e.g. Werner & Pfleiderer's ZSK series,
or a Banbury or other mixer, having the capability of heating and
effecting the desired level of mechanical work (agitation) on the
reactants for the grafting step. In one embodiment, grafting is
conducted in an extruder, and particularly a twin screw extruder. A
nitrogen blanket is maintained at the feed section of the extruder
to minimize the introduction of air.
[0030] Grafting may also be conducted in an extruder, such as a
twin-screw extruder. A nitrogen blanket is maintained at the feed
section of the extruder to minimize the introduction of air. In
another embodiment, the olefinic carboxylic acylating agent may be
injected at one injection point, or is alternatively injected at
two injection points in a zone of the extruder without significant
mixing e.g. a transport zone. Such injection may result in an
improved efficiency of the grafting and leads to a lower gel
content.
[0031] Suitable extruders are generally known available for
conducting grafting, and the prior dehydration procedure. The
dehydration of the polymer substrate and subsequent grafting
procedures may be performed in separate extruders set up in series.
Alternatively, a single extruder having multiple treatment or
reaction zones may be used to sequentially conduct the separate
operations within one piece of equipment. Illustrations of suitable
extruders are set forth, e.g., in U.S. Pat. No. 3,862,265 and U.S.
Pat. No. 5,837,773, which descriptions are incorporated herein by
reference.
[0032] In forming the acylated olefin copolymers, the olefin
copolymer generally is fed to plastic processing equipment such as
an extruder, intensive mixer or masticator, heated to a temperature
of at least 60.degree., for example, 150.degree. to 240.degree. C.,
and the ethylenically unsaturated carboxylic acid reagent and
free-radical initiator are separately co-fed to the molten
copolymer to effect grafting. The reaction is carried out
optionally with mixing conditions to effect grafting of the olefin
copolymers. If molecular weight reduction and grafting are
performed simultaneously, illustrative mixing conditions are
described in U.S. Pat. No. 5,075,383, which are incorporated herein
by reference. The processing equipment is generally purged with
nitrogen to prevent oxidation of the copolymer and to aid in
venting unreacted reagents and byproducts of the grafting reaction.
The residence time in the processing equipment is controlled to
provide for the desired degree of acylation and to allow for
purification of the acylated copolymer via venting. Mineral or
synthetic lubricating oil may optionally be added to the processing
equipment after the venting stage to dissolve the acylated
copolymer.
[0033] The grafting reaction may also be carried out in
solvent-free or essentially solvent free environment. Accordingly,
the grafting reaction may be performed in the absence of
hydrocarbon solvents. The avoidance of hydrocarbon solvents during
the grafting reaction, such as alkanes (e.g., hexane), eliminates
or significantly reduces the risk and problem of undesired side
reactions of such solvents during the grafting reaction which can
form undesired grafted alkyl succinic anhydride by-products and
impurities. Also, reduced amounts of transient unfunctionalized
polymer (ungrafted polymer) are present after grafting in
solventless grafting reactions, which results in a more active
product. Therefore, the resulting copolymer intermediate is a more
active product. A reduction is achieved in levels of undesirable
grafted solvent (i.e., grafted hexyl succinic anhydride) and
transient unfunctionalized (nongrafted) copolymer.
[0034] Hydrocarbon solvents that may be omitted according to
certain embodiments of the present disclosure include solvents that
generally are more volatile than the reactants of the grafting
reaction described herein, for example, solvents having a boiling
point less than about 150.degree. C. under standard atmospheric
pressure conditions (i.e., approximately 14.7 lb./in.sup.2
absolute). The solvents that may be omitted include, for example,
open-chain aliphatic compounds such as C.sub.9 or lower alkanes,
alkenes and alkynes (e.g., C.sub.5 to C.sub.8 alkanes such as
hexane); aromatic hydrocarbons (e.g., compounds having a benzene
nucleus such as benzene and toluene); alicyclic hydrocarbons such
as saturated cyclic hydrocarbons (e.g., cyclohexane); ketones; or
any combinations of these. In one embodiment, it is desirable to
omit all solvents having boiling points approximating or lower than
that of nonane under standard atmospheric conditions. Some
conventional grafting reactions have been performed in the presence
of considerable amounts of hydrocarbon solvent, such as
approximately 15% to 60% hexane content. By comparison, in one
embodiment of the present disclosure, the total amount of these
types of such solvents in the grafting reaction mass does not
exceed 0.5 wt. % content thereof.
[0035] The grafted copolymer intermediate exits from the die face
of the extruder either immediately after grafting, or after
shearing and vacuum stripping (discussed below in more detail) if
performed in different sections of the same extruder or a separate
extruder arranged in series with the extruder in which grafting is
conducted.
[0036] The resulting copolymer intermediate comprises an acylated
olefin copolymer characterized by having carboxylic acid acylating
functionality randomly within its structure. The amount of
carboxylic acid acylating agent (e.g., maleic anhydride) that is
grafted onto the prescribed copolymer backbone (i.e., the copolymer
substrate) is important. This parameter is referred to herein as
the degree of grafting (DOG), further described as the mass
percentage of acylating agent on the acylated copolymer. The DOG
generally is in the range of 0.5 to 3.0 wt. %, particularly in the
range of 1.5 to 2.5 wt. %, and more particularly in the range of
1.7 to 2.3 wt. %, of carboxylic acid acylating agent grafted on the
copolymer backbone.
[0037] The DOG value of a particular additive reaction product may
be determined either by infrared peak ratio analysis of acid or
anhydride moiety versus copolymer alkyl functionality or by
titration (Total Acid/Anhydride Number) (TAN) of the additive
reaction product. The TAN value in turn can be used to estimate the
degree of grafting (DOG).
[0038] The carboxylic reactant is grafted onto the prescribed
copolymer backbone to provide 0.15 to 0.75 carboxylic groups per
1000 number average molecular weight units (Mn) of the copolymer
backbone, desirably 0.2 to 0.5 carboxylic groups per 1000 number
average molecular weight. For example, a copolymer substrate with
M.sub.n of 20,000 is grafted with 3 to 15 carboxylic groups per
copolymer chain or 1.5 to 7.5 moles of maleic anhydride per mole of
copolymer. A copolymer with M.sub.n of 100,000 is grafted with 15
to 75 carboxylic groups per copolymer chain or 7.5 to 37.5 moles of
maleic anhydride per copolymer chain. The minimum level of
functionality is the level needed to achieve the minimum
satisfactory dispersancy performance.
[0039] The molecular weight of the acylated olefin copolymer, i.e.,
the copolymer intermediate, may be reduced by mechanical, thermal,
or chemical means, or a combination thereof. Techniques for
degrading or reducing the molecular weight of such copolymers are
generally known in the art. The number average molecular weight is
reduced to suitable level for use in single grade or multigrade
lubricating oils.
[0040] In one embodiment, the initial copolymer intermediate has an
initial number average molecular weight ranging from about 1,000 to
about 500,000 upon completion of the grafting reaction. In one
embodiment, to prepare an additive intended for use in multigrade
oils, the copolymer intermediate's number average molecular weight
is reduced down to a range of about 1,000 to about 80,000.
[0041] Alternatively, grafting and reduction of the high molecular
weight olefin copolymer may be done simultaneously. In another
alternative, the high molecular weight olefin copolymer may be
first reduced to the prescribed molecular weight before grafting.
When the olefin copolymer's average molecular weight is reduced
before grafting, its number average molecular weight is
sufficiently reduced to a value below about 80,000, e.g., in the
range of about 1,000 to 80,000.
[0042] Reduction of the molecular weight of the copolymer
intermediate, or the olefin copolymer feed material during or prior
to grafting, to a prescribed lower molecular weight typically is
conducted in the absence of a solvent or in the presence of a base
oil, using either mechanical, thermal, or chemical means, or
combination of these means. Generally, the copolymer intermediate,
or olefin copolymer, is heated to a molten condition at a
temperature in the range of about 250.degree. C. to about
350.degree. C. and it is then subjected to mechanical shear,
thermally or chemical induced cleavage or combination of said
means, until the copolymer intermediate (or olefin copolymer) is
reduced to the prescribed molecular weight. The shearing may be
effected within an extruder section, such as described, e.g., in
U.S. Pat. No. 5,837,773, which descriptions are incorporated herein
by reference. Alternatively, mechanical shearing may be conducted
by forcing the molten copolymer intermediate (or olefin copolymer)
through fine orifices under pressure or by other mechanical
means.
[0043] Upon completion of the grafting reaction, unreacted
carboxylic reactant and free radical initiator usually are removed
and separated from the copolymer intermediate before further
functionalization is performed on the copolymer intermediate. The
unreacted components may be eliminated from the reaction mass by
vacuum stripping, e.g., the reaction mass may be heated to
temperature of about 150.degree. C. to about 450.degree. C. under
agitation with a vacuum applied for a period sufficient to remove
the volatile unreacted graft monomer and free radical initiator
ingredients. Vacuum stripping may be performed in an extruder
section equipped with venting means.
[0044] The copolymer intermediate may be pelletized before further
processing in accordance with embodiments of the disclosure herein.
Pelletization of the copolymer intermediate helps to isolate the
intermediate product and reduce contamination thereof until further
processing is conducted thereon at a desired time.
[0045] The copolymer intermediate may be formed into pellets by a
variety of process methods commonly practiced in the art of
plastics processing. Such techniques include underwater
pelletization, ribbon or strand pelletization or conveyor belt
cooling. When the strength of the copolymer is inadequate to form
into strands, the preferred method is underwater pelletization.
Temperatures during pelletization should not exceed 30.degree. C.
Optionally, a surfactant can be added to the cooling water during
pelletization to prevent pellet agglomeration.
[0046] The mixture of water and quenched copolymer pellets is
conveyed to a dryer such as a centrifugal drier for removal of
water. Pellets may be collected in a box or plastic bag at any
volume for storage and shipment. Under some conditions of storage
and/or shipment at ambient conditions, pellets may tend to
agglomerate and stick together. The pellets may be ground by
mechanical methods to provide high surface area solid pieces for
easy and quick dissolution into oil.
[0047] The pelletized copolymer intermediate may be supplied as an
unground or ground form of the pellets. The pelletized acylated
copolymer intermediate is dissolved in solvent neutral oil. The
pellets generally are dissolved in the solvent at an introduction
level of from about 5 wt. % to about 25 wt. %, particularly about
10 wt. % to about 15 wt. %, and more particularly about 12 wt. % to
about 13 wt. %, based on the resulting solution (solute and
solvent) viscosity.
[0048] The pelletized copolymer intermediate can be dissolved in
the solvent neutral at temperature of, for example, about
135.degree. C. to about 165.degree. C. with mechanical stirring
under a nitrogen blanket. The dissolving mixture may be sparged
with inert gas during the dissolution for about 4 to 16 hours. Such
treatment may be performed in a continuous stirred process vessel
of suitable capacity.
[0049] The inert sparging gas may be nitrogen. The dissolution and
sparging, if used, may be prior to the subsequent amination
procedure. One or more spargers are located within the vessel at
locations submerged beneath the surface of the solution, preferably
near the bottom of the solution, and bubble inert gas through the
solution. Nitrogen sparging removes moisture from the dissolved
copolymer intermediate and solvent oil. Importantly, the removal of
moisture from the copolymer intermediate may act to convert any
polymeric dicarboxylic diacids present back to the desired
copolymeric dicarboxylic anhydride form.
[0050] For instance, where maleic anhydride is used as the grafting
monomer, some portion of the pelletized copolymer intermediate may
inadvertently transform to a copolymeric succinic diacid form. In
general, this change is more apt to occur as a function of a longer
shelf life. The conducting of nitrogen sparging during dissolution
of the copolymer intermediate and prior to amination has the
benefit of converting the copolymeric succinic diacid back into the
desired active polymeric succinic anhydride form before the
copolymer intermediate is further reacted and functionalized (e.g.,
aminated). Consequently, a more highly functionalized and active
aminated product may be obtained in subsequent processing. The
conversion of polymeric succinic diacid back into the active
polymeric succinic anhydride form can be monitored by measuring the
viscosity of the solution. The solution viscosity decreases
significantly from an initial higher value down to a steady-state
value upon conversion of all or essentially all of the polymeric
succinic diacid back into the desired polymeric succinic anhydride
form.
[0051] The neutral oil may be selected from Group I base stock,
Group II base stock, Group III base stock, Group IV or
poly-alpha-olefins (PAO), or base oil blends thereof.
[0052] The base stock or base stock blend preferably has a saturate
content of at least 65%, more preferably at least 75%; a sulfur
content of less than 1%, preferably less than 0.6%, by weight; and
a viscosity index of at least 85, preferably at least 100. Such
base stocks may be defined as follows: [0053] (i) Group I: base
stocks containing less than 90% saturates and/or greater than 0.03%
sulfur and having a viscosity index greater than or equal to 80 and
less than 120 using test methods specified in Table 1 of the
American Petroleum Institute (API) publication "Engine Oil
Licensing and Certification Sheet" Industry Services Department,
14.sup.th Ed., December 1996, Addendum I, December 1998; [0054]
(ii) Group II: base stocks containing greater than or equal to 90%
saturates and/or greater than 0.03% sulfur and having a viscosity
index greater than or equal to 80 and less than 120 using test
methods specified in Table 1 referenced above; [0055] (iii) Group
III: base stocks which are less than or equal to 0.03 wt % sulfur,
greater than or equal to 90% saturates, and greater than or equal
to 120 using test methods specified in Table 1 referenced above.
[0056] (iv) Group IV: base stocks which comprise PAO's.
[0057] For these definitions, saturates level may be determined by
ASTM D 2007, the viscosity index maybe determined by ASTM D 2270;
and sulfur content by any one of ASTM D 2622, ASTM D 4294, ASTM D
4927, or ASTM D 3120.
[0058] The dissolved pelletized copolymer intermediate possessing
carboxylic acid acylating functions subsequently reacted with an
amine compound. The amine may be selected from compounds such as
described, e.g., in U.S. Pat. Nos. 4,863,623, 5,075,383, and
6,107,257, which descriptions are incorporated herein by
reference.
[0059] In one embodiment, the amine compound may be selected from
the group consisting of: [0060] (a) an N-arylphenylenediamine
represented by the formula:
[0060] ##STR00001## in which Ar is aromatic and R.sup.1 is --H,
--NH.sub.2, --(--NH-Aryl).sub.n-H, --(--NH-Alkyl).sub.n--H,
--NH-arylalkyl, a branched or straight chain radical having from 4
to 24 carbon atoms that can be alkyl, alkenyl, alkoxyl, aralkyl,
alkaryl, hydroxyalkyl or aminoalkyl, R.sup.2 is (--NH.sub.2,
--(NH(CH.sub.2).sub.n--).sub.m--NH.sub.2,
--(CH.sub.2).sub.n--NH.sub.2, -aryl-NH.sub.2, in which n and m each
has a value from 1 to 10, and R.sup.3 is hydrogen, alkyl, alkenyl,
alkoxyl, aralkyl, alkaryl having from 4 to 24 carbon atoms, [0061]
(b) an aminocarbazole represented by the formula:
[0061] ##STR00002## in which R and R.sup.1 represent hydrogen or an
alkyl, alkenyl, or alkoxyl radical having from 1 to 14 carbon
atoms, [0062] (c) an aminoindole represented by the formula:
[0062] ##STR00003## in which R represents hydrogen or an alkyl
radical having from 1 to 14 carbon atoms, [0063] (d) an
amino-indazolinone represented by the formula:
[0063] ##STR00004## in which R is hydrogen or an alkyl radical
having from 1 to 14 carbon atoms, [0064] (e) an
aminomercaptotriazole represented by the formula:
[0064] ##STR00005## in which R can be absent or can be
C.sub.1-C.sub.10 linear or branched hydrocarbon selected from the
group consisting of alkyl, aryl, alkaryl, or arylalkyl. [0065] (f)
an aminopyrimidine represented by the formula:
[0065] ##STR00006## in which R represents hydrogen or an alkyl or
alkoxyl radical having from 1 to 14 carbon atoms.
[0066] In one embodiment, the amine compound may be, e.g., an
N-arylphenylenediamine represented by the general formula:
##STR00007##
in which R.sup.1 is hydrogen, --NH-aryl, --NH-arylalkyl,
--NH-alkyl, or a branched or straight chain radical having from 4
to 24 carbon atoms that can be alkyl, alkenyl, alkoxyl, aralkyl,
alkaryl, hydroxyalkyl or aminoalkyl; R.sup.2 is --NH.sub.2,
CH.sub.2--(CH.sub.2).sub.n--NH.sub.2, CH.sub.2-aryl-NH.sub.2, in
which n has a value from 1 to 10 and R.sup.3 is hydrogen, alkyl,
alkenyl, alkoxyl, aralkyl, alkaryl having from 4 to 24 carbon
atoms.
[0067] Particularly useful amines in the present disclosure are the
N-arylphenylenediamines, more specifically the
N-phenylphenylenediamines, for example,
N-phenyl-1,4-phenylenediamine, N-phenyl-1,3-phenylendiamine, and
N-phenyl-1,2-phenylenediamine.
[0068] Illustrations of other useful amines include those described
in U.S. Pat. Nos. 4,863,623 and 6,107,257, which are incorporated
herein by reference.
[0069] It is desirable that the amines contain only one primary
amine group so as to avoid coupling and/or gelling of the olefin
copolymers.
[0070] The reaction between the copolymer having grafted thereon
carboxylic acid acylating function and the prescribed amine
compound may be conducted by heating a solution of the copolymer
substrate under inert conditions and then adding the amine compound
to the heated solution generally with mixing to effect the
reaction. It is convenient to employ an oil solution of the
copolymer substrate heated to 120.degree. to 175.degree. C., while
maintaining the solution under a nitrogen blanket. The amine
compound may be added to this solution and the reaction is effected
under the noted conditions.
[0071] The amine compound may be dissolved with a surfactant and
added to a mineral or synthetic lubricating oil or solvent solution
containing the acylated olefin copolymer. The solution of amine and
olefin copolymer may be heated with agitation under an inert gas
purge at a temperature in the range of 120.degree. to 200.degree.
C. as described in U.S. Pat. No. 5,384,371, the disclosure of which
is herein incorporated by reference. The reactions may be carried
out conveniently in a stirred reactor under nitrogen purge.
[0072] In one aspect, a polymeric succinic anhydride oil solution
is reacted with N-phenyl-1,4-phenylenediamines, along with
ethoxylated lauryl alcohol in a reactor carried out at 165.degree.
C.
[0073] Surfactants which may be used in carrying out the reaction
of the acylated olefin copolymer with the polyamine(s) include but
are not limited to those characterized as having (a) solubility
characteristics compatible with mineral or synthetic lubricating
oil, (b) boiling point and vapor pressure characteristics so as not
to alter the flash point of the oil and (c) polarity suitable for
solubilizing the polyamine(s).
[0074] A suitable class of such surfactants includes the reaction
products of aliphatic and aromatic hydroxy compounds with ethylene
oxide, propylene oxide or mixtures thereof. Such surfactants are
commonly known as aliphatic or phenolic alkoxylates. Useful
surfactants can include those surfactants that contain a functional
group, e.g., --OH, capable of reacting with the acylated olefin
copolymer. Ethoxylated lauryl alcohol
(C.sub.12H.sub.25(OCH.sub.2CH.sub.2).sub.nOH) is also useful
herein. Ethoxylated lauryl alcohol is identified under CAS no.
9002-92-0. The ethoxylated lauryl alcohol is a processing aid and
viscosity stabilizer for the final multifunctional viscosity
modifier product. The ethoxylated lauryl alcohol facilitates the
amine charge into the reaction mixture. It is a reaction agent
ensuring that no acylated functionality is left unreacted. Any
unreacted acylated functionality may cause undesirable viscosity
drift in finished lubrication formulations. The surfactant also
modifies the viscoelastic response in the multifunctional viscosity
modifier product allowing improved handling at low temperature (70
to 90.degree. C.).
[0075] The quantity of surfactant used depends in part on its
ability to solubilize the amine. Typically, concentrations of 5 to
40 wt. % amine are employed. The surfactant may also be added
separately, instead of or in addition to the concentrates discussed
above, such that the total amount of surfactant in the finished
additive is 10 wt. % or less.
[0076] The highly grafted, multi-functional olefin copolymers of
the present disclosure may be incorporated into lubricating oil in
any convenient way. Thus, the highly grafted, multi-functional
olefin copolymers may be added directly to the lubricating oil by
dispersing or dissolving the same in the lubricating oil at the
desired level of concentration. Such blending into the lubricating
oil may occur at room temperature or elevated temperatures.
Alternatively, the highly grafted, multi-functional olefin
copolymers can be blended with a suitable oil-soluble
solvent/diluent (such as benzene, xylene, toluene, lubricating base
oils and petroleum distillates) to form a concentrate, and then
blending the concentrate with a lubricating oil to obtain the final
formulation. Such additive concentrates will typically contain (on
an active ingredient (A.I.) basis) from about 3 to about 45 wt. %,
and preferably from about 10 to about 35 wt. %, highly grafted,
multi-functional olefin copolymer additive, and typically from
about 20 to 90 wt %, preferably from about 40 to 60 wt %, base oil
based on the concentrate weight.
[0077] Several of the amine reactants have the tendency to form
highly colored oxidation products, comprising members of the class
of staining amine antioxidants. Unreacted amine which is left in
the oil solution after the amination reaction may give rise to
undesirable and/or unstable color in the oil solution. The acylated
olefin copolymer also may be color stabilized after the amination
reaction, such as by reacting the acylated olefin copolymer with a
C.sub.7 to C.sub.12 alkyl aldehyde (e.g., nonyl aldehyde). For
example, the reaction may proceed when the alkyl aldehyde agent is
added in an amount of about 0.2 to about 0.6 wt. % under similar
temperature and pressure conditions as used in the amination
reaction for about 2 to about 6 hours.
[0078] To increase the purity of the aminated, color stabilized
acylated olefin copolymer product, it may be filtered by either bag
or cartridge filtration or both in series.
[0079] As indicated above, the copolymer intermediate may be
prepared in the absence of solvent. Also, the copolymer
intermediate may be received in pelletized or bale form as a
starting material for performing the additional
functionalization(s), viz. amination and color stabilization, on
the grafted copolymer intermediate. The copolymer intermediate need
not be received directly from the die face of an extruder or
similar grafting reaction vessel, but instead the copolymer
intermediate has been vacuum stripped of unreacted reactants and
pelletized before these further functionalizations are performed on
it. Therefore, the pelletized copolymer intermediate contains less
contaminants than a product that has been grafted in the presence
of a solvent (which can lead to side reaction products) and/or
aminated immediately after the grafting reaction as part of a
continuous process flow arrangement (which leaves unreacted
components as impurities in the reaction mass).
[0080] In addition, the use of inert gas sparging on the copolymer
intermediate dissolved in neutral oil prior to amination has the
benefit of converting polymeric succinic diacid present back into
the desired active polymeric succinic anhydride form before the
copolymer intermediate is further reacted and functionalized (e.g,
aminated).
[0081] Also, since unreacted graft monomer, e.g., maleic anhydride
is effectively removed after the grafting step during vacuum
stripping that precedes pelletizing and dissolution, amination
proceeds more efficiently. That is, the presence of unreacted graft
monomers are undesirable during the amination step as they may
compete with the grafted copolymer (polymer intermediate) in
reactions with the amine, reducing the level of functionalization
achieved.
[0082] Therefore, the multi-functional reaction end product of
embodiments of the present disclosure may contain fewer impurities
(i.e., unreacted reactants, side reaction products and by-products)
and may be more active for a given amount thereof. In one
embodiment, the additive reaction product may contain less than 0.1
wt. % total impurities comprising unreacted reactants, side
reaction products and reaction by-products. The remainder may be
composed of active grafted, multifunctionalized olefin copolymer
either entirely, or substantially in combination with some minor
amount of beneficial or inert additive introduced during
processing, such as an antioxidant or colorant, which does not
significantly reduce or impair the activity of the product
compound.
[0083] The highly grafted, multi-functional olefin copolymer
product compounds of the present disclosure optionally may be
post-treated so as to impart additional properties necessary or
desired for a specific lubricant application. Post-treatment
techniques are well known in the art and include boronation,
phosphorylation, glycolation, ethylene-carbonation, and
maleination.
[0084] Lubricating oil formulations for diesel engines as described
herein may conventionally contain additional additives that will
supply the characteristics that are required in the formulations.
Among these types of additives are included additional viscosity
index improvers, antioxidants, corrosion inhibitors, detergents,
dispersants, pour point depressants, antiwear agents, antifoaming
agents, demulsifiers and friction modifiers. These additives are
provided in what is commonly called a dispersant/inhibitor (DI)
package.
[0085] One component of the DI package is a metal-containing or
ash-forming detergent that functions as both a detergent to reduce
or remove deposits and as an acid neutralizer or rust inhibitors,
thereby reducing wear and corrosion and extending engine life.
Detergents generally comprise a polar head with a long hydrophobic
tail. The polar head comprises a metal salt of an acidic organic
compound. The salts may contain a substantially stoichiometric
amount of the metal in which case they are usually described as
normal or neutral salts, and would typically have a total base
number or TBN (as can be measured by ASTM D2896) of from 0 to 80. A
large amount of a metal base may be incorporated by reacting excess
metal compound (e.g., an oxide or hydroxide) with an acidic gas
(e.g., carbon dioxide). The resulting overbased detergent comprises
neutralized detergent as the outer layer of a metal base (e.g.
carbonate) micelle. Such overbased detergents may have a TBN of 150
or greater, and typically will have a TBN of from 250 to 450 or
more.
[0086] Detergents that may be used include oil-soluble neutral and
overbased sulfonates, phenates, sulfurized phenates,
thiophosphonates, salicylates, and naphthenates and other
oil-soluble carboxylates of a metal, particularly the alkali or
alkaline earth metals, e.g., barium, sodium, potassium, lithium,
calcium, and magnesium. The most commonly used metals are calcium
and magnesium, which may both be present in detergents used in a
lubricant, and mixtures of calcium and/or magnesium with sodium.
Particularly convenient metal detergents are neutral and overbased
calcium sulfonates having TBN of from 20 to 450, neutral and
overbased calcium phenates and sulfurized phenates having TBN of
from 50 to 450 and neutral and overbased magnesium or calcium
salicylates having a TBN of from 20 to 450. Combinations of
detergents, whether overbased or neutral or both, may be used. In
one preferred lubricating oil composition.
[0087] Detergents generally useful in the formulation of
lubricating oil compositions also include "hybrid" detergents
formed with mixed surfactant systems, e.g., phenate/salicylates,
sulfonate/phenates, sulfonate/salicylates,
sulfonates/phenates/salicylates, as described, for example, in U.S.
Pat. Nos. 6,153,565, 6,281,179, 6,429,178 and 6,429,179.
[0088] It is not unusual to add a detergent or other additive, to a
lubricating oil, or additive concentrate, in a diluent, such that
only a portion of the added weight represents an active ingredient
(A.I.). For example, detergent may be added together with an equal
weight of diluent in which case the "additive" is 50% A.I.
detergent. As used herein, the term weight percent (wt. %), when
applied to a detergent or other additive refers to the weight of
active ingredient. Detergents conventionally comprise from about
0.5 to about 5 wt. %, preferably from about 0.8 to about 3.8 wt. %,
most preferably from about 1.2 to about 3 wt. % of a lubricating
oil composition formulated for use in a heavy duty diesel
engine.
[0089] Dispersants maintain in suspension materials resulting from
oxidation during use that are insoluble in oil, thus preventing
sludge flocculation and precipitation, or deposition on metal
parts. Dispersants useful in the context of the disclosure include
the range of nitrogen-containing, ashless (metal-free) dispersants
known to be effective to reduce formation of deposits upon use in
gasoline and diesel engines, when added to lubricating oils. The
ashless, dispersants comprise an oil soluble polymeric long chain
backbone having functional groups capable of associating with
particles to be dispersed. Typically, such dispersants have amine,
amine-alcohol or amide polar moieties attached to the polymer
backbone, often via a bridging group. The ashless dispersant may
be, for example, selected from oil soluble salts, esters,
amino-esters, amides, imides and oxazolines of long chain
hydrocarbon-substituted mono- and polycarboxylic acids or
anhydrides thereof; thiocarboxylate derivatives of long chain
hydrocarbons; long chain aliphatic hydrocarbons having polyamine
moieties attached directly thereto; and Mannich condensation
products formed by condensing a long chain substituted phenol with
formaldehyde and polyalkylene polyamine.
[0090] Generally, each mono- or dicarboxylic acid-producing moiety
will react with a nucleophilic group (amine or amide) and the
number of functional groups in the polyalkenyl-substituted
carboxylic acylating agent will determine the number of
nucleophilic groups in the finished dispersant.
[0091] The polyalkenyl moiety of the dispersant described herein
has a number average molecular weight of at least about 1800,
preferably between 1800 and 3000, such as between 2000 and 2800,
more preferably from about 2100 to 2500, and most preferably from
about 2200 to about 2400. The molecular weight of a dispersant is
generally expressed in terms of the molecular weight of the
polyalkenyl moiety as the precise molecular weight range of the
dispersant depends on numerous parameters including the type of
polymer used to derive the dispersant, the number of functional
groups, and the type of nucleophilic group employed.
[0092] The polyalkenyl moiety from which dispersants may be derived
has a narrow molecular weight distribution (MWD), also referred to
as polydispersity, as determined by the ratio of weight average
molecular weight (M.sub.w) to number average molecular weight
(M.sub.n). Specifically, polymers from which the dispersants may be
derived have a M.sub.w/M.sub.n of from about 1.5 to about 2.0,
preferably from about 1.5 to about 1.9, most preferably from about
1.6 to about 1.8.
[0093] Suitable hydrocarbons or polymers employed in the formation
of the dispersants of the disclosure include homopolymers,
interpolymers or lower molecular weight hydrocarbons. One family of
such polymers comprise polymers of ethylene and/or at least one
C.sub.3 to C.sub.28 alpha-olefin wherein the polymer contains
carbon-to-carbon unsaturation, preferably a high degree of terminal
ethenylidene unsaturation. Useful alpha-olefin monomers and
comonomers include, for example, propylene, butene-1, hexene-1,
octene-1,4-methylpentene-1, decene-1, dodecene-1, tridecene-1,
tetradecene-1, pentadecene-1, hexadecene-1, heptadecene-1,
octadecene-1, nonadecene-1, and mixtures thereof (e.g., mixtures of
propylene and butene-1, and the like). Exemplary of such polymers
are propylene homopolymers, butene-1 homopolymers,
ethylene-propylene copolymers, ethylene-butene-1 copolymers,
propylene-butene copolymers and the like, wherein the polymer
contains at least some terminal and/or internal unsaturation.
Preferred polymers are unsaturated copolymers of ethylene and
propylene and ethylene and butene-1. The interpolymers of
disclosure may contain a minor amount, e.g. 0.5 to 5 mole % of a
C.sub.4 to C.sub.18 non-conjugated diolefin comonomer. However, it
is preferred that the polymers comprise only alpha-olefin
homopolymers, interpolymers of alpha-olefin comonomers and
interpolymers of ethylene and alpha-olefin comonomers. The molar
ethylene content of the polymers may be in the range of 0 to 80%,
and more preferably 0 to 60%. When propylene and/or butene-1 are
employed as comonomer(s) with ethylene, the ethylene content of
such copolymers is most preferably between 15 and 50%, although
higher or lower ethylene contents may be present.
[0094] Polyisobutylene polymers that may be employed as the polymer
backbone to make the dispersants described above are generally
based on a hydrocarbon chain of from about 1800 to 3000. Methods
for making polyisobutylene are known. Polyisobutylene may be
functionalized by halogenation (e.g. chlorination), the thermal
"ene" reaction, or by free radical grafting using a catalyst (e.g.
peroxide).
[0095] The hydrocarbon or polymer backbone can be functionalized,
e.g., with carboxylic acid producing moieties (preferably acid or
anhydride moieties) selectively at sites of carbon-to-carbon
unsaturation on the polymer or hydrocarbon chains, or randomly
along chains using any of the three processes mentioned above or
combinations thereof, in any sequence.
[0096] Processes for reacting polymeric hydrocarbons with
unsaturated carboxylic acids, anhydrides or esters and the
preparation of derivatives from such compounds are disclosed in
U.S. Pat. Nos. 3,087,936; 3,172,892; 3,215,707; 3,231,587;
3,272,746; 3,275,554; 3,381,022; 3,442,808; 3,565,804; 3,912,764;
4,110,349; 4,234,435; 5,777,025; 5,891,953; as well as EP 0 382 450
B1; and CA-1,335,895.
[0097] The functionalized oil-soluble polymeric hydrocarbon
backbone is then derivatized with a nitrogen-containing
nucleophilic reactant, such as an amine, amino-alcohol, amide, or
mixture thereof, to form a corresponding derivative. Amine
compounds are preferred. Useful amine compounds for derivatizing
functionalized polymers comprise at least one amine and can
comprise one or more additional amine or other reactive or polar
groups. These amines may be hydrocarbyl amines or may be
predominantly hydrocarbyl amines in which the hydrocarbyl group
includes other groups, e.g., hydroxy groups, alkoxy groups, amide
groups, nitrites, imidazoline groups, and the like. Particularly
useful amine compounds include mono- and polyamines, e.g.,
polyalkene and polyoxyalkylene polyamines of about 2 to 60, such as
2 to 40 (e.g., 3 to 20) total carbon atoms having about 1 to 12,
such as 3 to 12, preferably 3 to 9, most preferably form about 6 to
about 7 nitrogen atoms per molecule. Mixtures of amine compounds
may advantageously be used, such as those prepared by reaction of
alkylene dihalide with ammonia. Preferred amines are aliphatic
saturated amines, including, for example, 1,2-diaminoethane;
1,3-diaminopropane; 1,4-diaminobutane; 1,6-diaminohexane;
polyethylene amines such as diethylene triamine; triethylene
tetramine; tetraethylene pentamine; and polypropyleneamines such as
1,2-propylene diamine; and di-(1,2-propylene)triamine. Example of
suitable amines can be found in U.S. Pat. Nos. 4,938,881;
4,927,551; 5,230,714; 5,241,003; 5,565,128; 5,756,431; 5,792,730;
and 5,854,186.
[0098] Other useful amine compounds include: alicyclic diamines
such as 1,4-di(aminomethyl)cyclohexane and heterocyclic nitrogen
compounds such as imidazolines. Another useful class of amines is
the polyamido and related amido-amines as disclosed in U.S. Pat.
Nos. 4,857,217; 4,956,107; 4,963,275; and 5,229,022. Also usable is
tris(hydroxymethyl)amino methane (TAM) as described in U.S. Pat.
Nos. 4,102,798; 4,113,639; 4,116,876; and UK 989,409. Dendrimers,
star-like amines, and comb-structured amines may also be used.
Similarly, one may use condensed amines, as described in U.S. Pat.
No. 5,053,152. The functionalized polymer is reacted with the amine
compound using conventional techniques as described, for example,
in U.S. Pat. Nos. 4,234,435 and 5,229,022, as well as in
EP-A-208,560.
[0099] A preferred dispersant composition is one comprising at
least one polyalkenyl succinimide, which is the reaction product of
a polyalkenyl substituted succinic anhydride (e.g., PIBSA) and a
polyamine (PAM) that has a coupling ratio of from about 0.65 to
about 1.25, preferably from about 0.8 to about 1.1, most preferably
from about 0.9 to about 1. In the context of this disclosure,
"coupling ratio" may be defined as a ratio of the number of
succinyl groups in the PIBSA to the number of primary amine groups
in the polyamine reactant.
[0100] Another class of high molecular weight ashless dispersants
comprises Mannich base condensation products. Generally, these
products are prepared by condensing about one mole of a long chain
alkyl-substituted mono- or polyhydroxy benzene with about 1 to 2.5
moles of carbonyl compound(s) (e.g., formaldehyde and
paraformaldehyde) and about 0.5 to 2 moles of polyalkylene
polyamine, as disclosed, for example, in U.S. Pat. No. 3,442,808.
Such Mannich base condensation products may include a polymer
product of a metallocene catalyzed polymerization as a substituent
on the benzene group, or may be reacted with a compound containing
such a polymer substituted on a succinic anhydride in a manner
similar to that described in U.S. Pat. No. 3,442,808. Examples of
functionalized and/or derivatized olefin polymers synthesized using
metallocene catalyst systems are described in the publications
identified supra.
[0101] Preferred dispersants include those in which greater than
about 50 wt. % of the nitrogen is non-basic. The normally basic
nitrogen of nitrogen-containing dispersants can be rendered
non-basic by reacting the nitrogen-containing dispersant with a
so-called "capping agent". Conventionally, nitrogen-containing
dispersants have been capped to reduce the adverse effect such
dispersants have on the nitrile seals used in engines. Numerous
capping agents and methods are known. The reaction of a
nitrogen-containing dispersant and tautomeric acetoacetate (e.g.,
ethyl acetoacetate (EAA)) is described, for example, in U.S. Pat.
Nos. 4,839,071; 4,839,072 and 4,579,675. The reaction of a
nitrogen-containing dispersant and formalin and/or formic acid is
described, for example, in U.S. Pat. No. 3,185,704. Capping of
nitrogen-containing dispersants with epoxides is described, for
example, in U.S. Pat. Nos. 3,267,704; 3,373,021 and 3,373,111. The
reaction product of a nitrogen-containing dispersant and other
known capping agents are described in U.S. Pat. Nos. 3,366,569
(acrylonitrile); 4,636,322 and 4,663,064 (glycolic acid);
4,612,132; 5,334,321; 5,356,552; 5,716,912; 5,849,676; 5,861,363
carbonates, e.g., ethylene carbonate) 4,686,054 (maleic anhydride
or succinic anhydride); 3,254,025; 3,087,963 (boron). The foregoing
list is not exhaustive and other methods of capping
nitrogen-containing dispersants are known to those skilled in the
art.
[0102] For the purpose of reducing rate at which the kinematic
viscosity of lubricating oil increases in the presence of soot and
acids generated upon use of heavy duty diesel engines provided with
EGR systems that operate in a condensing mode, nitrogen-containing
dispersants in which greater than about 50 wt. % of the nitrogen is
rendered non-basic by reaction with formalin, formic acid, epoxides
and tautomeric acetoacetate (e.g., ethyl acetoacetate), are
preferred.
[0103] Additional additives may be incorporated into the
compositions of the disclosure to enable particular performance
requirements to be met. Examples of additives which may be included
in the lubricating oil compositions of the present disclosure are
metal rust inhibitors, viscosity index improvers (other than
polymer i, iii and/or iii), corrosion inhibitors, oxidation
inhibitors, friction modifiers, anti-foaming agents, anti-wear
agents and pour point depressants (other than polymer iii). Some
are discussed in further detail below.
[0104] Dihydrocarbyl dithiophosphate metal salts are frequently
used as antiwear and antioxidant agents. The metal may be an alkali
or alkaline earth metal, or aluminum, lead, tin, molybdenum,
manganese, nickel or copper. The zinc salts are most commonly used
in lubricating oil in amounts of 0.1 to 10, preferably 0.2 to 2 wt.
%, based upon the total weight of the lubricating oil
composition.
[0105] The preferred zinc dihydrocarbyl dithiophosphates are oil
soluble salts of dihydrocarbyl dithiophosphoric acids and may be
represented by the following formula:
##STR00008##
wherein R and R' may be the same or different hydrocarbyl radicals
containing from 1 to 18, preferably 2 to 12, carbon atoms and
including radicals such as alkyl, alkenyl, aryl, arylalkyl, alkaryl
and cycloaliphatic radicals. Particularly preferred as R and R'
groups are alkyl groups of 2 to 8 carbon atoms. Thus, the radicals
may, for example, be ethyl, n-propyl, i-propyl, n-butyl, i-butyl,
sec-butyl, amyl, n-hexyl, i-hexyl, n-octyl, decyl, dodecyl,
octadecyl, 2-ethylhexyl, phenyl, butylphenyl, cyclohexyl,
methylcyclopentyl, propenyl, butenyl. In order to obtain oil
solubility, the total number of carbon atoms (i.e. R and R') in the
dithiophosphoric acid will generally be about 5 or greater. The
zinc dihydrocarbyl dithiophosphate can therefore comprise zinc
dialkyl dithiophosphates. The disclosed embodiments are
particularly useful when used with lubricant compositions
containing phosphorus levels of from about 0.02 to about 0.12 wt.
%, preferably from about 0.03 to about 0.10 wt. %. More preferably,
the phosphorous level of the lubricating oil composition will be
less than about 0.08 wt. %, such as from about 0.05 to about 0.08
wt. %.
[0106] Oxidation inhibitors or antioxidants reduce the tendency of
mineral oils to deteriorate in service. Oxidative deterioration can
be evidenced by sludge in the lubricant, varnish-like deposits on
the metal surfaces, and by viscosity growth. Such oxidation
inhibitors include hindered phenols, alkaline earth metal salts of
alkylphenolthioesters having preferably C.sub.5 to C.sub.12 alkyl
side chains, calcium nonylphenol sulfide, oil soluble phenates and
sulfurized phenates, phosphosulfurized or sulfurized hydrocarbons
or esters, phosphorous esters, metal thiocarbamates, oil soluble
copper compounds as described in U.S. Pat. No. 4,867,890, and
molybdenum-containing compounds.
[0107] Aromatic amines having at least two aromatic groups attached
directly to the nitrogen constitute another class of compounds that
is frequently used for antioxidancy. While these materials may be
used in small amounts, preferred embodiments of the present
disclosure are free of these compounds. They are preferably used in
only small amounts, i.e., up to 0.4 wt. %, or more preferably
avoided altogether other than such amount as may result as an
impurity from another component of the composition.
[0108] Typical oil soluble aromatic amines having at least two
aromatic groups attached directly to one amine nitrogen contain
from 6 to 16 carbon atoms. The amines may contain more than two
aromatic groups. Compounds having a total of at least three
aromatic groups in which two aromatic groups are linked by a
covalent bond or by an atom or group (e.g., an oxygen or sulfur
atom, or a--CO--, --SO.sub.2-- or alkylene group) and two are
directly attached to one amine nitrogen also considered aromatic
amines having at least two aromatic groups attached directly to the
nitrogen. The aromatic rings are typically substituted by one or
more substituents selected from alkyl, cycloalkyl, alkoxy, aryloxy,
acyl, acylamino, hydroxy, and nitro groups. The amount of any such
oil soluble aromatic amines having at least two aromatic groups
attached directly to one amine nitrogen should preferably not
exceed 0.4 wt. % active ingredient.
[0109] Representative examples of suitable viscosity modifiers are
polyisobutylene, copolymers of ethylene and propylene,
polymethacrylates, methacrylate copolymers, copolymers of an
unsaturated dicarboxylic acid and a vinyl compound, interpolymers
of styrene and acrylic esters, and partially hydrogenated
copolymers of styrene/isoprene, styrene/butadiene, and
isoprene/butadiene, as well as the partially hydrogenated
homopolymers of butadiene and isoprene.
[0110] Friction modifiers and fuel economy agents that are
compatible with the other ingredients of the final oil may also be
included. Examples of such materials include glyceryl monoesters of
higher fatty acids, for example, glyceryl mono-oleate; esters of
long chain polycarboxylic acids with diols, for example, the butane
diol ester of a dimerized unsaturated fatty acid; oxazoline
compounds; and alkoxylated alkyl-substituted mono-amines, diamines
and alkyl ether amines, for example, ethoxylated tallow amine and
ethoxylated tallow ether amine.
[0111] Other known friction modifiers comprise oil-soluble metallic
compounds such as organo-molybdenum compounds, organo-titanium
compounds and organo-tungsten compounds. Such organo-metallic
friction modifiers may also provide antioxidant and antiwear
credits to a lubricating oil composition. As an example of such oil
soluble organo-metallic compounds, there may be mentioned the
carboxylates, dithiocarbamates, dithiophosphates,
dithiophosphinates, xanthates, thioxanthates, sulfides, and the
like, and mixtures thereof. Particularly preferred organo-metallic
compounds include molybdenum dithiocarbamates,
dialkyldithiophosphates, alkyl xanthates, and alkylthioxanthates.
Other organo-metallic compounds may include the oil soluble
titanium and tungsten carboxylates.
[0112] The terms "oil-soluble" or "dispersible" used herein do not
necessarily indicate that the compounds or additives are soluble,
dissolvable, miscible, or capable of being suspended in the oil in
all proportions. These do mean, however, that they are, for
instance, soluble or stably dispersible in oil to an extent
sufficient to exert their intended effect in the environment in
which the oil is employed. Moreover, the additional incorporation
of other additives may also permit incorporation of higher levels
of a particular additive, if desired.
[0113] Pour point depressants, otherwise known as lube oil flow
improvers (LOFI), lower the minimum temperature at which the fluid
will flow or can be poured. Such additives are well known. Typical
of those additives that improve the low temperature fluidity of the
fluid are C.sub.8 to C.sub.18 dialkyl fumarate/vinyl acetate
copolymers, and polymethacrylates. Foam control may be provided by
an antifoamant of the polysiloxane type, for example, silicone oil
or polydimethyl siloxane.
[0114] Some of the above-mentioned additives can provide a
multiplicity of effects; thus for example, a single additive may
act as a dispersant-oxidation inhibitor. This approach is well
known and need not be further elaborated herein.
[0115] When lubricating compositions contain one or more of the
above-mentioned additives comprising the DI package, each additive
is typically blended into the base oil in an amount that enables
the additive to provide its desired function. Representative
effective amounts of such additives, when used in crankcase
lubricants, are listed below. All the values listed are stated as
mass percent active ingredient.
TABLE-US-00001 Mass % Mass % Additive (Broad) (Typical) Metal
Detergents 0.1 to 15.0 0.29 to 9.0 Dispersants 0.1 to 10.0 1.0 to
6.0 Corrosion Inhibitor 0 to 5.0 0 to 1.5 Metal Dihydrocarbyl
Dithiophosphate 0.1 to 6.0 0.1 to 4.0 Antioxidant 0 to 5.0 0.01 to
2.0 Pour Point Depressant 0.01 to 5.0 0.01 to 1.5 Antifoaming Agent
0 to 5.0 0.001 to 0.15 Supplemental Antiwear Agents 0 to 1.0 0 to
0.5 Friction Modifiers 0 to 5.0 0 to 1.5 Viscosity Modifier 0.01 to
10.0 0.25 to 3.0 Basestock Balance Balance
[0116] In the preparation of lubricating oil formulations it is
common practice to introduce the additives in the form of 10 to 80
wt. % active ingredient concentrates in hydrocarbon oil, e.g.
mineral lubricating oil, or other suitable solvent.
[0117] Usually these concentrates may be diluted with 3 to 100,
e.g., 5 to 40, parts by weight of lubricating oil per part by
weight of the additive package in forming finished lubricants, e.g.
crankcase motor oils. The purpose of concentrates, of course, is to
make the handling of the various materials less difficult and
awkward as well as to facilitate solution or dispersion in the
final blend. Thus, the highly grafted, multi-functional olefin
copolymer would usually be employed in the form of a 10 to 50 wt. %
concentrate, for example, in a lubricating oil fraction. In one
embodiment, the amount of concentrate in a finished lubricating oil
is from about 0.05 weight percent to about 8 weight percent of the
total lubricating oil.
[0118] The highly grafted, multi-functional olefin copolymers of
the present disclosure will generally be used in admixture with a
lube oil base stock, comprising an oil of lubricating viscosity,
including natural lubricating oils, synthetic lubricating oils and
mixtures thereof.
[0119] Natural oils include animal oils and vegetable oils (e.g.,
castor, lard oil), liquid petroleum oils and hydrorefined,
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. The synthetic lubricating oils used in this disclosure
include one of any number of commonly used synthetic hydrocarbon
oils, which include, but are not limited to, poly-alpha-olefins,
alkylated aromatics, alkylene oxide polymers, copolymers,
terpolymer, interpolymers and derivatives thereof here the terminal
hydroxyl groups have been modified by esterification,
etherification, etc, esters of dicarboxylic acids, and
silicon-based oils.
[0120] The highly grafted, multi-functional olefin copolymer
products of the present disclosure find their primary utility in
lubricating oil compositions which employ a base oil in which the
additives are dissolved or dispersed in amount sufficient to
provide the desired functionality. Such base oils may be natural,
synthetic or mixtures thereof. Base oils suitable for use in
preparing the lubricating oil compositions for use in diesel
engines operating on bio-diesel fuels include those conventionally
employed as crankcase lubricating oils for spark-ignited and
compression-ignited internal combustion engines, such as automobile
and truck engines, marine and railroad diesel engines, and the
like. The internal combustion engines which may be advantageously
lubricated with crankcase lubricating oils containing the highly
grafted olefin copolymer additive set forth herein include diesel
fuel powered engines, particularly diesel engines operating on
bio-diesel components. The diesel engines that may be particularly
affected include heavy duty diesel engines, including those
equipped with exhaust gas recirculation (EGR) systems.
[0121] Among other advantages, these additives have been observed
in performance tests, such as described in the examples below, to
provide improved soot dispersing and/or viscosity stabilizing
performance on diesel engines operated on bio-diesel fuels as
compared to the same engines using the same lubricants operated on
non-biodiesel fuels. Bio-diesel fuels are typically fatty acid
ethyl or methyl esters derived animal fats and from edible or
non-edible vegetable oils such as, but not limited to, canola,
sunflower, rapeseed, soyabean, linseed, and palm oils.
[0122] The cooled lubricated EGR engines within the scope of the
present disclosure include heavy and light duty diesel engines that
or operated on a variety of bio-diesel fuels. The engines may
include EGR engines cooled by the circulation or heat exchange of
water, water/hydrocarbon blends or mixtures, water/glycol mixtures,
and/or air or gas.
[0123] The lubricating oil composition of the present disclosure
was tested on a diesel engine operating on an ultra-low sulfur
diesel PC-10 fuel devoid of bio-diesel components and an engine
operating on a similar diesel fuel containing 20 wt. % bio-diesel
components. The engine tests were extended T-11 engine tests. As
shown in FIG. 1, curve A represents a viscosity soot curve for a
lubricant used in the engine operating on bio-diesel fuel. Curve B
represents the results for the engine operating on a fuel devoid of
bio-diesel components. As shown in FIG. 1, the lubricant
composition of the disclosure provided a synergistic decrease in
viscosity increase at a higher soot loading when the engine was
operated on a bio-diesel fuel as compared to the engine operating
on a fuel devoid of bio-diesel components. The result was totally
unexpected in view of the increased tendency of bio-diesel fuels to
contribute to the soot loading of the lubricants.
[0124] The present disclosure is further directed to a method of
extending lubricant drain intervals in a vehicle is contemplated.
The method includes adding to and operating in the crankcase of the
vehicle the lubricating oil composition described above.
[0125] The disclosures of all patents, articles and other materials
described herein are hereby incorporated, in their entirety, into
this specification by reference. Compositions described as
"comprising" a plurality of defined components are to be construed
as including compositions formed by admixing the defined plurality
of defined components The principles, preferred embodiments and
modes of operation of the present disclosure have been described in
the foregoing specification. What applicants submit, however, is
not to be construed as limited to the particular embodiments
disclosed, since the disclosed embodiments are regarded as
illustrative rather than limiting. Changes may be made by those
skilled in the art without departing from the spirit of the
disclosed embodiments.
* * * * *