U.S. patent application number 11/266789 was filed with the patent office on 2007-05-10 for lubricating oil compositions.
Invention is credited to Jai G. Bansal, Stuart Briggs, Chin Chu, Jacob Emert, Rolfe J. Hartley.
Application Number | 20070105731 11/266789 |
Document ID | / |
Family ID | 37674937 |
Filed Date | 2007-05-10 |
United States Patent
Application |
20070105731 |
Kind Code |
A1 |
Chu; Chin ; et al. |
May 10, 2007 |
Lubricating oil compositions
Abstract
A lubricating oil composition formulated with a viscosity index
(VI) improver composition including a combination of an ethylene
.alpha.-olefin copolymer having no greater than 66 mass % of units
derived from ethylene, and a linear diblock copolymer including at
least one block derived primarily from a vinyl aromatic hydrocarbon
monomer, and at least one block derived primarily from diene
monomer.
Inventors: |
Chu; Chin; (West wood,
NJ) ; Hartley; Rolfe J.; (Rockaway, NJ) ;
Briggs; Stuart; (Edison, NJ) ; Emert; Jacob;
(Brooklyn, NJ) ; Bansal; Jai G.; (Warren,
NJ) |
Correspondence
Address: |
Infineum USA L.P.;Law Department
1900 E. Linden Ave.
P.O. Box 710
Linden
NJ
07036
US
|
Family ID: |
37674937 |
Appl. No.: |
11/266789 |
Filed: |
November 4, 2005 |
Current U.S.
Class: |
508/542 |
Current CPC
Class: |
C10N 2020/019 20200501;
C10N 2030/42 20200501; C10N 2030/40 20200501; C10N 2020/04
20130101; C10M 2205/028 20130101; C10M 2205/022 20130101; C10N
2030/02 20130101; C10M 161/00 20130101; C10M 2203/1006 20130101;
C10M 2207/14 20130101; C10M 169/041 20130101; C10M 2205/08
20130101; C10N 2040/252 20200501; C10M 2223/045 20130101; C10M
2205/026 20130101; C10N 2030/45 20200501; C10N 2040/25 20130101;
C10M 143/00 20130101; C10M 2205/04 20130101; C10M 2215/28 20130101;
C10N 2030/68 20200501; C10M 2229/02 20130101; C10N 2030/43
20200501; C10M 2207/262 20130101; C10N 2040/253 20200501; C10M
2205/022 20130101; C10M 2205/024 20130101; C10M 2205/04 20130101;
C10M 2205/06 20130101; C10M 2205/04 20130101; C10M 2205/06
20130101; C10N 2060/02 20130101; C10M 2223/045 20130101; C10N
2010/04 20130101; C10M 2223/045 20130101; C10N 2010/04 20130101;
C10M 2205/04 20130101; C10M 2205/06 20130101; C10N 2060/02
20130101 |
Class at
Publication: |
508/542 |
International
Class: |
C10L 1/22 20060101
C10L001/22 |
Claims
1. A lubricating oil composition comprising a major amount of an
oil of a Group II or higher base oil of lubricating viscosity and a
minor amount of a polymer composition comprising at least a first
polymer that is an ethylene .alpha.-olefin copolymer comprising no
greater than 66 mass % of units derived from ethylene; and a second
polymer comprising a linear diblock copolymer comprising at least
one block derived primarily from a vinyl aromatic hydrocarbon
monomer, and at least one block derived primarily from diene
monomer.
2. A lubricating oil composition as claimed in claim 1, wherein the
first polymer and the second polymer are present in a mass % ratio
of from about 80:20 to about 20:80.
3. A lubricating oil composition as claimed in claim 2, wherein
said ethylene .alpha.-olefin copolymer is an ethylene-propylene
copolymer and said linear diblock copolymer is at least one diblock
copolymer comprising at least one polystyrene block, and at least
one block derived from isoprene, butadiene, or a mixture
thereof.
4. A lubricating oil composition as claimed in claim 3, wherein
said ethylene .alpha.-olefin copolymer is an ethylene-propylene
copolymer and said linear diblock copolymer is at least one diblock
copolymer selected from the group consisting of hydrogenated
styrene/butadiene block copolymers and hydrogenated
styrene/isoprene block copolymers.
5. A lubricating oil composition as claimed in claim 3, wherein
said ethylene-propylene copolymer comprises from about 20 to about
66 mass % of units derived from ethylene.
6. A lubricating oil composition as claimed in claim 3, wherein
said ethylene-propylene copolymer has a Shear Stability Index (SSI)
value of from about 20% to about 50% (30 cycles), and the polydiene
block of the diblock copolymer comprises from about 40 mass % to 90
mass % derived from isoprene and from about 10 mass % to about 60
mass % derived from butadiene.
7. A lubricating oil composition as claimed in claim 1, wherein
said base oil of lubricating viscosity has a saturates content of
at least about 80.
8. A lubricating oil composition as claimed in claim 1, containing
less than about 30 mass % of Group I base oil.
9. A lubricating oil composition as claimed in claim 1, further
comprising a nitrogenous dispersant derived from a polyalkene
having a number average molecular weight (M.sub.n) of greater than
about 1500, wherein said base oil of lubricating viscosity has a
saturates content of at least about 80%, and wherein said
lubricating oil composition contains less than about 0.4 mass % of
sulfur, less than about 0.12 mass % phosphorus and less than about
1.2 mass % of sulfated ash.
10. A method of operating an internal combustion engine, said
method comprising lubricating said engine with a lubricating oil
composition as claimed in claim 1, and operating the lubricating
engine.
11. A method of operating an internal combustion engine, said
method comprising lubricating said engine with a lubricating oil
composition as claimed in claim 9, and operating the lubricating
engine.
12. The method as claimed in claim 11, wherein said engine is a
heavy duty diesel (HDD) engine.
13. A method of improving the soot-handling properties of a
lubricating oil composition for the lubrication of an internal
combustion engine, which method comprises formulating said
lubricating oil composition with a polymer composition comprising
at least a first polymer that is an ethylene .alpha.-olefin
copolymer comprising no greater than 66 mass % of units derived
from ethylene; and a second polymer comprising a linear diblock
copolymer comprising at least one block derived primarily from a
vinyl aromatic hydrocarbon monomer, and at least one block derived
primarily from diene monomer.
14. The method as claimed in claim 13, wherein said lubricating oil
composition is further formulated with a nitrogenous dispersant
derived from a polyalkene having a number average molecular weight
(M.sub.n) of greater than about 1500, and a base oil of lubricating
viscosity having a saturates content of at least about 80%, and
wherein said lubricating oil composition contains less than about
0.4 mass % of sulfur, less than about 0.12 mass % phosphorus and
less than about 1.2 mass % of sulfated ash.
Description
FIELD OF THE INVENTION
[0001] The invention is directed to lubricating oil compositions
formulated with blended viscosity index improver compositions. More
specifically, the present invention is directed to lubricating oil
compositions comprising a major amount of a Group II or higher base
oil and a viscosity index improver composition containing at least
two polymeric viscosity index improvers which lubricating oil
composition, provide improved soot dispersing properties than can
be achieved with the use of an equivalent amount of either polymer
individually, while simultaneously providing acceptable shear
stability performance.
BACKGROUND OF THE INVENTION
[0002] Lubricating oil compositions for use in crankcase engine
oils comprise a major amount of base oil and minor amounts of
additives that improve the performance and increase the useful life
of the lubricant. Crankcase lubricating oil compositions
conventionally contain polymeric components that are used to
improve the viscometric performance of the engine oil, i.e., to
provide multigrade oils such as SAE 5W-30, 10W-30 and 10W-40. These
viscosity performance enhancing material, commonly referred to as
viscosity index (VI) improvers, can effectively increase the
viscosity of a lubricating oil formulation at higher temperatures
(typically above 100.degree. C.) without increasing excessively the
high shear rate viscosity at lower temperatures (typically -10 to
-15.degree. C.). These oil-soluble polymers are generally of higher
molecular weight (>100,000 M.sub.n) compared to the base oil and
other components. Well known classes of polymers suitable for use
as viscosity index improvers for lubricating oil compositions
include ethylene .alpha.-olefin copolymers, polymethacrylates,
diblock copolymers having a vinyl aromatic segment and a
hydrogenated polydiene segment, and star copolymers and
hydrogenated isoprene linear and star polymers.
[0003] Viscosity index improvers for lubricating oil compositions
advantageously increase the viscosity of the lubricating oil
composition at higher temperatures when used in relatively small
amounts (have a high thickening efficiency (TE)), provide reduced
lubricating oil resistance to cold engine starting (as measured by
"CCS" performance) and be resistant to mechanical degradation and
reduction in molecular weight in use (have a high shear stability
index (SSI)). It is also preferred that the viscosity index
improver to display soot-dispersing characteristics in lubricating
oil compositions. Further, as viscosity index improving polymers
are often provided to lubricant blenders as a concentrate in which
the viscosity index improving polymer is diluted in oil, which
concentrate is then blended into a greater volume of oil to provide
the desired lubricant product. Therefore, it is further preferred
that viscosity index improving polymers can be blended into
concentrates in relatively large amounts, without causing the
concentrate to have an excessively high concentrate the kinematic
viscosity. Some polymers are excellent in some of the above
properties, but are deficient in one or more of the others.
[0004] It would be advantageous to be able provide lubricating oil
compositions that simultaneously provide high overall viscometric
performance, and soot dispersancy.
[0005] PCT Publication WO 96/17041, Jun. 6, 1996, discloses certain
blends of star-branched styrene-isoprene polymers and ethylene
.alpha.-olefin copolymers. The publication describes the addition
of a an amount of the ethylene .alpha.-olefin copolymer to the
star-branched styrene-isoprene polymer as being effective to
improve the dimensional stability of the star branched polymer so
that the star branched polymer can be formed as a stable, solid
bale.
[0006] U.S. Pat. No. 4,194,057, Mar. 18, 1980, discloses viscosity
index improving compositions containing a combination of a certain
class of relatively low molecular weight vinyl aromatic/conjugated
diene diblock copolymers and ethylene .alpha.-olefin copolymer. The
patent describes the specified class of vinyl aromatic/conjugated
diene diblock copolymer as being relatively insoluble in oil and
that blending with ethylene .alpha.-olefin copolymer improves
solubility and allows for the formation of polymer
concentrates.
[0007] PCT Publication WO 2004/087849, Oct. 14, 2004, discloses a
viscosity index improver composition containing a blend of a select
class of high ethylene content ethylene .alpha.-olefin copolymer,
and vinyl aromatic/diene diblock copolymer, in certain proportions,
which are describes as providing good low temperature performance
and durability.
SUMMARY OF THE INVENTION
[0008] In accordance with a first aspect of the invention, there is
provided a lubricating oil composition comprising a major amount of
a Group II or higher base oil and a viscosity index (VI) improver
composition comprising a first polymer that is an amorphous or
semi-crystalline ethylene .alpha.-olefin copolymer comprising no
greater than 66 mass % of units derived from ethylene; and a second
polymer comprising a linear diblock copolymer comprising at least
one block derived primarily from a vinyl aromatic hydrocarbon
monomer, and at least one block derived primarily from diene
monomer.
[0009] In accordance with a third aspect of the invention, there is
provided a lubricating oil composition of the first aspect in which
the first polymer and the second polymer are present in a mass %
ratio of from about 80:20 to about 20:80.
[0010] In accordance with a third aspect of the invention, there is
provided a lubricating oil composition as in the first or second
aspect, further comprising a nitrogenous dispersant derived from a
polyalkene having a number average molecular weight (M.sub.n) of
greater than about 1500, wherein the base oil of the lubricating
oil composition has a saturates content of at least about 80%, and
said lubricating oil composition contains less than about 0.4 mass
% of sulfur, less than about 0.12 mass % phosphorus and less than
about 1.2 mass % of sulfated ash.
[0011] In accordance with a fourth aspect of the invention, there
is provided a method of operating an internal combustion engine,
particularly a heavy duty diesel (HDD) engine, which method
comprises lubricating said engine with a lubricating oil
composition as in the first, second or third aspect, and operating
the lubricated engine.
[0012] In accordance with a fifth aspect of the invention, there is
provided a method of improving the soot-handling properties of a
lubricating oil composition for the lubrication of an internal
combustion engine, particularly a heavy duty diesel (HDD) engine,
which method comprises formulating the lubricating oil composition
with a polymer composition comprising at least a first polymer that
is an ethylene .alpha.-olefin copolymer comprising no greater than
66 mass % of units derived from ethylene; and a second polymer
comprising a linear diblock copolymer comprising at least one block
derived primarily from a vinyl aromatic hydrocarbon monomer, and at
least one block derived primarily from diene monomer.
[0013] In accordance with a sixth aspect of the invention, there is
provided a method as in the fifth aspect, wherein said lubricating
oil composition is further formulated with a nitrogenous dispersant
derived from a polyalkene having a number average molecular weight
(M.sub.n) of greater than about 1500, and a base oil of lubricating
viscosity having a saturates content of at least about 80%, and
wherein said lubricating oil composition contains less than about
0.4 mass % of sulfur, less than about 0.12 mass % phosphorus and
less than about 1.2 mass % of sulfated ash.
[0014] In accordance with a seventh aspect of the invention, there
is provided a use of a polymer composition comprising at least a
first polymer that is an ethylene .alpha.-olefin copolymer
comprising no greater than 66 mass % of units derived from
ethylene; and a second polymer comprising a linear diblock
copolymer comprising at least one block derived primarily from a
vinyl aromatic hydrocarbon monomer, and at least one block derived
primarily from diene monomer to improve the soot handling
characteristics of a lubricating oil composition for the
lubrication of an internal combustion engine, particularly a heavy
duty diesel (HDD) engine.
[0015] Other and further objects, advantages and features of the
present invention will be understood by reference to the following
specification.
DETAILED DESCRIPTION OF THE INVENTION
[0016] Ethylene-.alpha.-olefin copolymers (OCP) useful in the
practice of the invention include amorphous or semi-crystalline OCP
synthesized from ethylene monomer and at least one other
.alpha.-olefin comonomer. The average mass % of the OCP derived
from ethylene (hereinafter "ethylene content") of OCP useful in the
present invention can be as low as about 20 mass %, preferably no
lower than about 25 mass %; more preferably no lower than about 30
mass %. The maximum ethylene content can be about 66 mass %.
Preferably the ethylene content of the OCP is from about 25 to 55
mass %, more preferably from about 35 to 55 mass %. Crystalline
ethylene-.alpha.-olefin copolymers excluded from the compositions
of the present invention are defined as those comprising greater
than about 60 mass ethylene (e.g. from greater than 66 to about 90
mass % ethylene).
[0017] Ethylene content can be measured by ASTM-D3900 for
ethylene-propylene copolymers containing between 35 mass % and 85
mass % ethylene. Above 85 mass ASTM-D2238 can be used to obtain
methyl group concentration, which is related to percent ethylene in
an unambiguous manner for ethylene-propylene copolymers. When
comonomers other than propylene are employed, no ASTM tests
covering a wide range of ethylene contents are available; however,
proton and carbon-13 nuclear magnetic resonance spectroscopy can be
employed to determine the composition of such polymers. These are
absolute techniques requiring no calibration when operated such
that all nuclei of a given element contribute equally to the
spectra. For ethylene content ranges not covered by the ASTM tests
for ethylene-propylene copolymers, as well as for any
ethylene-propylene copolymers, the aforementioned nuclear magnetic
resonance methods can also be used.
[0018] "Crystallinity" in ethylene-alpha-olefin polymers can be
measured using X-ray techniques known in the art as well as by the
use of a differential scanning calorimetry (DSC) test. DSC can be
used to measure crystallinity as follows: a polymer sample is
annealed at room temperature (e.g., 20-25.degree. C.) for at least
24 hours before the measurement. Thereafter, the sample is first
cooled to -100.degree. C. from room temperature, and then heated to
150 C at 10.degree. C./min. Crystallinity is calculated as follows:
% .times. .times. Crystallinity = ( .DELTA. .times. .times. H )
.times. x methylene .times. 14 4110 .times. 100 .times. % ;
##EQU1## wherein .SIGMA..DELTA.H (J/g) is the sum of the heat
absorbed by the polymer above its glass transition temperature,
x.sub.methylene is the molar fraction of ethylene in the polymer
calculated, e.g., from proton NMR data, 14 (g/mol) is the molar
mass of a methylene unit, and 4110 (J/mol) is the heat of fusion
for a single crystal of polyethylene at equilibrium.
[0019] As noted, the ethylene-.alpha.-olefin copolymers are
comprised of ethylene and at least one other .alpha.-olefin. The
"other" .alpha.-olefins typically include those containing 3 to 18
carbon atoms, e.g., propylene, butene-1, pentene-1, etc. Preferred
are .alpha.-olefins having 3 to 6 carbon atoms, particularly for
economic reasons. The most preferred OCP are those comprised of
ethylene and propylene.
[0020] As is well known to those skilled in the art, copolymers of
ethylene and higher alpha-olefins such as propylene can optionally
include other polymerizable monomers. Typical of these other
monomers are non-conjugated dienes such as the following
non-limiting examples: [0021] a. straight chain acyclic dienes such
as: 1,4-hexadiene; 1,6-octadiene; [0022] b. branched chain acyclic
dienes such as: 5-methyl-1,4-hexadiene; 3,7-dimethyl-1,6-octadiene;
3,7-dimethyl-1,7-octadiene and the mixed isomers of dihydro-mycene
and dihydroocinene; [0023] c. single ring alicyclic dienes such as:
1,4-cyclohexadiene; 1,5-cyclooctadiene; and 1,5-cyclododecadiene;
and [0024] d. multi-ring alicyclic fused and bridged ring dienes
such as: tetrahydroindene; methyltetrahydroindene;
dicyclopentadiene; bicyclo-(2,2,1)-hepta-2,5-diene; alkenyl,
alkylidene, cycloalkenyl and cycloalkylidene norbornenes such as
5-methylene-2-norbornene (MNB), 5-ethylidene-2-norbornene (ENB),
5-propylene-2-norbornene, 5-isopropylidene-2-norbornene,
5-(4-cyclopentenyl)-2-norbornene;
5-cyclohexylidene-2-norbornene.
[0025] Of the non-conjugated dienes typically used to prepare these
copolymers, dienes containing at least one of the double bonds in a
strained ring are preferred. The most preferred diene is
5-ethylidene-2-norbornene (ENB). When present, the amount of diene
(on a weight basis) in the copolymer can be from greater than 0% to
about 20%; preferably from greater than 0% to about 15%; most
preferably greater than 0% to about 10%.
[0026] The molecular weight of OCP useful in accordance with the
present invention can vary over a wide range since ethylene
copolymers having number-average molecular weights (M.sub.n) as low
as about 2,000 can affect the viscosity properties of an oleaginous
composition. The preferred minimum M.sub.n is about 10,000; the
most preferred minimum is about 20,000. The maximum M.sub.n can be
as high as about 12,000,000; the preferred maximum is about
1,000,000; the most preferred maximum is about 750,000. An
especially preferred range of number-average molecular weight for
OCP useful in the present invention is from about 15,000 to about
500,000; preferably from about 20,000 to about 250,000; more
preferably from about 25,000 to about 150,000. The term "number
average molecular weight", as used herein, refers to the number
average weight as measured by Gel Permeation Chromatography ("GPC")
with a polystyrene standard.
[0027] "Thickening Efficiency" ("TE") is representative of a
polymers ability to thicken oil per unit mass and is defined as: TE
= 2 c .times. .times. ln .times. .times. 2 .times. ln .function. (
kv oil + polymer kv oil ) ; ##EQU2## wherein c is polymer
concentration (grams of polymer/100 grams solution),
kv.sub.oil+polymer is kinematic viscosity of the polymer in the
reference oil, and kv.sub.oil is kinematic viscosity of the
reference oil.
[0028] "Shear Stability Index" ("SSr") measures the ability of
polymers used as V.I. improvers in crankcase lubricants to maintain
thickening power during SSI is indicative of the resistance of a
polymer to degradation under service conditions. The higher the
SSI, the less stable the polymer, i.e., the more susceptible it is
to degradation. SSI is defined as the percentage of polymer-derived
viscosity loss and is calculated as follows: SSI = 100 .times. kv
fresh - kv after kv fresh - kv oil ; ##EQU3## wherein kv.sub.fresh
is the kinematic viscosity of the polymer-containing solution
before degradation and kv.sub.after is the kinematic viscosity of
the polymer-containing solution after degradation. SSI is
conventionally determined using ASTM D6278-98 (known as the
Kurt-Orban (KO) or DIN bench test). The polymer under test is
dissolved in suitable base oil (for example, solvent extracted 150
neutral) to a relative viscosity of 9 to 15 centistokes at
100.degree. C. and the resulting fluid is pumped through the
testing apparatus specified in the ASTM D6278-98 protocol.
[0029] "Cold Cranking Simulator" ("CCS") is a measure of the
cold-cranking characteristics of crankcase lubricants and is
conventionally determined using a technique described in ASTM
D5293-92.
[0030] The OCP of the present invention preferably has an SSI (30
cycles) of from about 10 to about 60%, preferably from about 20 to
about 50%, more preferably from about 15 to about 35%.
[0031] Linear block copolymers useful in the practice of the
present invention comprise at least one block derived primarily
from vinyl aromatic hydrocarbon monomer, and at least one block
derived primarily from diene monomer. Useful vinyl aromatic
hydrocarbon monomers include those containing from 8 to about 16
carbon atoms such as aryl-substituted styrenes, alkoxy-substituted
styrenes, vinyl naphthalene, alkyl-substituted vinyl naphthalenes
and the like. Dienes, or diolefins, contain two double bonds,
commonly located in conjugation in a 1,3 relationship. Olefins
containing more than two double bonds, sometimes referred to as
polyenes, are also considered within the definition of "diene" as
used herein. Useful dienes include those containing from 4 to about
12 carbon atoms, preferably from 8 to about 16 carbon atoms, such
as 1,3-butadiene, isoprene, piperylene, methylpentadiene,
phenylbutadiene, 3,4-dimethyl-1,3-hexadiene,
4,5-diethyl-1,3-octadiene, with 1,3-butadiene and isoprene being
preferred.
[0032] Linear block copolymers useful in the practice of the
present invention may be represented by the following general
formula: A.sub.z-(B-A).sub.y-B.sub.x wherein: A is a polymeric
block derived predominantly vinyl aromatic hydrocarbon monomer; B
is a polymeric block derived predominantly conjugated diene
monomer; x and z are, independently, a number equal to 0 or 1; and
y is a whole number ranging from 1 to about 15.
[0033] Useful tapered linear block copolymers may be represented by
the following general formula: A-A/B-B wherein: A is a polymeric
block derived predominantly from vinyl aromatic hydrocarbon
monomer; B is a polymeric block derived predominantly conjugated
diolefin monomer; and A/B is a tapered segment derived from both
vinyl aromatic hydrocarbon monomer and conjugated diolefin
monomer.
[0034] As used herein in connection with polymer block composition,
"predominantly" means that the specified monomer or monomer type
that is the principle component in that polymer block is present in
an amount of at least 85% by weight of the block.
[0035] Polymers prepared with diolefins will contain ethylenic
unsaturation, and such polymers are preferably hydrogenated. When
the polymer is hydrogenated, the hydrogenation may be accomplished
using any of the techniques known in the prior art. For example,
the hydrogenation may be accomplished such that both ethylenic and
aromatic unsaturation is converted (saturated) using methods such
as those taught, for example, in U.S. Pat. Nos. 3,113,986 and
3,700,633 or the hydrogenation may be accomplished selectively such
that a significant portion of the ethylenic unsaturation is
converted while little or no aromatic unsaturation is converted as
taught, for example, in U.S. Pat. Nos. 3,634,595; 3,670,054;
3,700,633 and Re 27,145. Any of these methods can also be used to
hydrogenate polymers containing only ethylenic unsaturation and
which are free of aromatic unsaturation.
[0036] The block copolymers may include mixtures of linear polymers
as disclosed above, having different molecular weights and/or
different vinyl aromatic contents as well as mixtures of linear
block copolymers having different molecular weights and/or
different vinyl aromatic contents. The use of two or more different
polymers may be preferred to a single polymer depending on the
rheological properties the product is intended to impart when used
to produce formulated engine oil.
[0037] The block copolymer may have a number average molecular
weight of between about 200,000 and about 1,500,000. A number
average molecular weight of between about 350,000 and about 900,000
is preferred. The amount of vinyl aromatic content of the copolymer
is preferably between about 5% and about 40% by weight of the
copolymer. For such copolymers, number average molecular weights
between about 85,000 and about 300,000 are acceptable.
[0038] Useful OCP and block copolymers include those prepared in
bulk, suspension, solution or emulsion. As is well known,
polymerization of monomers to produce hydrocarbon polymers may be
accomplished using free-radical, cationic and anionic initiators or
polymerization catalysts, such as transition metal catalysts used
for Ziegler-Natta and metallocene type (also referred to as
"single-site") catalysts.
[0039] Optionally, one or both types of VI improvers used in the
practice of the invention can be provided with nitrogen-containing
functional groups that impart dispersant capabilities to the VI
improver. One trend in the industry has been to use such
"multifunctional" VI improvers in lubricants to replace some or all
of the dispersant. Nitrogen-containing functional groups can be
added to a polymeric VI improver by grafting a nitrogen- or
hydroxyl-containing moiety, preferably a nitrogen-containing
moiety, onto the polymeric backbone of the VI improver
(functionalizing). Processes for the grafting of a
nitrogen-containing moiety onto a polymer are known in the art and
include, for example, contacting the polymer and
nitrogen-containing moiety in the presence of a free radical
initiator, either neat, or in the presence of a solvent. The free
radical initiator may be generated by shearing (as in an extruder)
or heating a free radical initiator precursor, such as hydrogen
peroxide.
[0040] The amount of nitrogen-containing grafting monomer will
depend, to some extent, on the nature of the substrate polymer and
the level of dispersancy required of the grafted polymer. To impart
dispersancy characteristics to both star and linear copolymers, the
amount of grafted nitrogen-containing monomer is suitably between
about 0.4 and about 2.2 wt. %, preferably from about 0.5 to about
1.8 wt. %, most preferably from about 0.6 to about 1.2 wt. %, based
on the total weight of grafted polymer.
[0041] Methods for grafting nitrogen-containing monomer onto
polymer backbones, and suitable nitrogen-containing grafting
monomers are known and described, for example, in U.S. Pat. No.
5,141,996, WO 98/13443, WO 99/21902, U.S. Pat. No. 4,146,489, U.S.
Pat. No. 4,292,414, and U.S. Pat. No. 4,506,056. (See also J
Polymer Science, Part A: Polymer Chemistry, Vol. 26, 1189-1198
(1988); J. Polymer Science, Polymer Letters, Vol. 20, 481-486
(1982) and J. Polymer Science, Polymer Letters, Vol. 21, 23-30
(1983), all to Gaylord Mehta and Degradation and Cross-linking of
Ethylene-Propylene Copolymer Rubber on Reaction with Maleic
Anhydride and/or Peroxides; J. Applied Polymer Science, Vol. 33,
2549-2558 (1987) to Gaylord, Mehta and Mehta.
[0042] Both the OCP and diblock copolymer components of the present
invention are available as commercial products. Infineum V534.TM.,
available from Infineum USA L.P. and Infineum UK Ltd. is an example
of a commercially available amorphous OCP. Examples of commercially
available styrene/hydrogenated isoprene linear diblock copolymers
include Infineum SV140.TM., Infineum SV150.TM. and Infineum
SV160.TM., available from Infineum USA L.P. and Infineum UK Ltd.;
Lubrizol.RTM. 7318, available from The Lubrizol Corporation; and
Septon 1001.TM. and Septon 1020.TM., available from Septon Company
of America (Kuraray Group). Suitable styrene/1,3-butadiene
hydrogenated block copolymers are sold under the tradename
Glissoviscal.TM. by BASF.
[0043] Compositions of the present invention contain the specified
OCP and block copolymers in a mass % ratio of from about 80:20 to
about 20:80, preferably from about 35:65 to about 65:35; more
preferably from about 45:55 to about 55:45. The polymer
compositions of the invention can be provided in the form of a
dimensionally stable, compounded solid polymer blend, or as a
concentrate, containing from about 3 to about 20 mass %, preferably
from about 6 to about 16 mass %, more preferably from about 9 to
about 12 mass % of polymer, in oil. Alternatively, concentrates in
accordance with present invention may comprise from about 0.6 to
about 16.0 mass %, preferably from about 2.1 to about 10.4 mass %,
more preferably from about 4.0 to about 6.6 mass % of amorphous OCP
and from about 2.1 to about 10.4 mass %, preferably from about 4.0
to about 6.6 mass % of the specified linear diblock copolymer.
[0044] Such concentrates may contain the polymer blend as the only
additive, or may further comprise additional additives,
particularly other polymeric additives, such as lubricating oil
flow improver ("LOFI"), also commonly referred to as pour point
depressant ("PPD"). The LOFI or PPD is used to lower the minimum
temperature at which the fluid will flow or can be poured and such
additives are well known. Typical of such additives are C.sub.8 to
C.sub.18 dialkyl fumarate/vinyl acetate copolymers,
polymethacrylates and styrene/maleic anhydride ester copolymers.
Concentrates of the present invention may contain from about 0 to
about 5 mass % of LOFI. Preferably, at least about 98 mass %, more
preferably at least about 99.5 mass %, of the concentrates of the
present invention are VI improver, LOFI and diluent oil.
[0045] Such VI improver concentrates can be prepared by dissolving
the VI improver polymer(s), and optional LOFI, in diluent oil using
well known techniques. When dissolving a solid VI improver polymer
to form a concentrate, the high viscosity of the polymer can cause
poor diffusivity in the diluent oil. To facilitate dissolution, it
is common to increase the surface are of the polymer by, for
example, pelletizing, chopping, grinding or pulverizing the
polymer. The temperature of the diluent oil can also be increased
by heating using, for example, steam or hot oil. When the diluent
temperature is greatly increased (such as to above 100.degree. C.),
heating should be conducted under a blanket of inert gas (e.g.,
N.sub.2 or CO.sub.2). The temperature of the polymer may also be
raised using, for example, mechanical energy imparted to the
polymer in an extruder or masticator. The polymer temperature can
be raised above 150.degree. C.; the polymer temperature is
preferably raised under a blanket of inert gas. Dissolving of the
polymer may also be aided by agitating the concentrate, such as by
stirring or agitating (in either the reactor or in a tank), or by
using a recirculation pump. Any two or more of the foregoing
techniques can also be used in combination. Concentrates can also
be formed by exchanging the polymerization solvent (usually a
volatile hydrocarbon such as, for example, propane, hexane or
cyclohexane) with oil. This exchange can be accomplished by, for
example, using a distillation column to assure that substantially
none of the polymerization solvent remains.
[0046] To provide a fully formulated lubricant, the solid copolymer
or VI improver concentrate can be dissolved in a major amount of an
oil of lubricating viscosity together with an additive package
containing other necessary or desired lubricant additives. Fully
formulated lubricants in accordance with the present invention may
comprise from about 0.4 to about 2.5 mass %, preferably from about
0.6 to about 1.7 mass %, more preferably from about 0.8 to about
1.2 mass % of the polymer composition of the present invention, in
oil. Alternatively, fully formulated lubricants in accordance with
the present invention may comprise from about 0.1 to about 2.0 mass
%, preferably from about 0.2 to about 1.1 mass more preferably from
about 0.4 to about 0.7 mass % of OCP and from about 0.1 to about
2.0 mass %, preferably from about 0.2 to about 1.1 mass % of the
specified linear diblock copolymer.
[0047] In one preferred embodiment, the polymer composition of the
present invention comprises an amorphous OCP having an SSI value of
from about 20% to about 50% (30 cycles), and the polydiene block of
the diblock copolymer is derived from about 40 mass % to about 90
mass % isoprene, and from about 10 mass % to about 60 mass %
butadiene units. In another preferred embodiment, the polymer
composition of the present invention comprises an amorphous OCP
having an SSI value of from about 20% to about 50% (30 cycles) and
the polydiene block of the diblock copolymer is derived from
amorphous butadiene units.
[0048] Oils of lubricating viscosity that are useful in the
practice of the present invention may be selected from natural
oils, synthetic oils and mixtures thereof.
[0049] Natural oils include animal oils and vegetable oils (e.g.,
castor oil, lard oil); liquid petroleum oils and hydro-refined,
solvent-treated or acid-treated mineral oils of the paraffinic,
naphthenic and mixed paraffinic-naphthenic types. Oils of
lubricating viscosity derived from coal or shale also serve as
useful base oils.
[0050] Synthetic lubricating oils include hydrocarbon oils and
halo-substituted hydrocarbon oils such as polymerized and
interpolymerized olefins (e.g., polybutylenes, polypropylenes,
propylene-isobutylene copolymers, chlorinated polybutylenes,
poly(1-hexenes), poly(1-octenes), poly(1-decenes)); alkylbenzenes
(e.g., dodecylbenzenes, tetradecylbenzenes, dinonylbenzenes,
di(2-ethylhexyl)benzenes); polyphenyls (e.g., biphenyls,
terphenyls, alkylated polyphenols); and alkylated diphenyl ethers
and alkylated diphenyl sulfides and derivative, analogs and
homologs thereof.
[0051] Alkylene oxide polymers and interpolymers and derivatives
thereof where the terminal hydroxyl groups have been modified by
esterification, etherification, etc., constitute another class of
known synthetic oils. These are exemplified by polyoxyalkylene
polymers prepared by polymerization of ethylene oxide or propylene
oxide, and the alkyl and aryl ethers of polyoxyalkylene polymers
(e.g., methyl-polyiso-propylene glycol ether having a molecular
weight of 1000 or diphenyl ether of poly-ethylene glycol having a
molecular weight of 1000 to 1500); and mono- and polycarboxylic
esters thereof, for example, the acetic acid esters, mixed
C.sub.3-C.sub.8 fatty acid esters and C.sub.13 Oxo acid diester of
tetraethylene glycol.
[0052] Another suitable class of synthetic oils comprises the
esters of dicarboxylic acids (e.g., phthalic acid, succinic acid,
alkyl succinic acids and alkenyl succinic acids, maleic acid,
azelaic acid, suberic acid, sebasic acid, fumaric acid, adipic
acid, linoleic acid dimer, malonic acid, alkylmalonic acids,
alkenyl malonic acids) with a variety of alcohols (e.g., butyl
alcohol, hexyl alcohol, dodecyl alcohol, 2-ethylhexyl alcohol,
ethylene glycol, diethylene glycol monoether, propylene glycol).
Examples of such esters include dibutyl adipate, di(2-ethylhexyl)
sebacate, di-n-hexyl fumarate, dioctyl sebacate, diisooctyl
azelate, diisodecyl azelate, dioctyl phthalate, didecyl phthalate,
dieicosyl sebacate, the 2-ethylhexyl diester of linoleic acid
dimer, and the complex ester formed by reacting one mole of sebacic
acid with two moles of tetraethylene glycol and two moles of
2-ethylhexanoic acid.
[0053] Esters useful as synthetic oils also include those made from
C.sub.5 to C.sub.12 monocarboxylic acids and polyols and polyol
esters such as neopentyl glycol, trimethylolpropane,
pentaerythritol, dipentaerythritol and tripentaerythritol.
[0054] Silicon-based oils such as the polyalkyl-, polyaryl-,
polyalkoxy- or polyaryloxysilicone oils and silicate oils comprise
another useful class of synthetic lubricants; such oils include
tetraethyl silicate, tetraisopropyl silicate,
tetra-(2-ethylhexyl)silicate,
tetra-(4-methyl-2-ethylhexyl)silicate, tetra-(p-tert-butyl-phenyl)
silicate, hexa-(4-methyl-2-ethylhexyl)disiloxane,
poly(methyl)siloxanes and poly(methylphenyl)siloxanes. Other
synthetic lubricating oils include liquid esters of
phosphorous-containing acids (e.g., tricresyl phosphate, trioctyl
phosphate, diethyl ester of decylphosphonic acid) and polymeric
tetrahydrofurans.
[0055] The oil of lubricating viscosity useful in the practice of
the present invention may comprise a Group II, Group III, Group IV
or Group V oil or blends of the aforementioned oils. The oil of
lubricating viscosity may also comprise a blend of Group I oil and
one or more of a Group II, Group III, Group IV or Group V oil,
containing up to about 30 mass %, preferably no greater than 15
mass %, more preferably no greater than 10 mass %, of Group I oil.
Definitions for the oils as used herein are the same as those found
in the American Petroleum Institute (API) publication "Engine Oil
Licensing and Certification System", Industry Services Department,
Fourteenth Edition, December 1996, Addendum 1, December 1998. Said
publication categorizes oils as follows: [0056] a) Group I oils
contain less than 90 percent saturates and/or greater than 0.03
percent sulfur and have a viscosity index greater than or equal to
80 and less than 120 using the test methods specified in Table 1.
[0057] b) Group II oils contain greater than or equal to 90 percent
saturates and less than or equal to 0.03 percent sulfur and have a
viscosity index greater than or equal to 80 and less than 120 using
the test methods specified in Table 1. Although not a separate
Group recognized by the API, Group II oils having a viscosity index
greater than about 110 are often referred to as "Group II+" oils.
[0058] c) Group III oils contain greater than or equal to 90
percent saturates and less than or equal to 0.03 percent sulfur and
have a viscosity index greater than or equal to 120 using the test
methods specified in Table 1. [0059] d) Group IV oils are
polyalphaolefins (PAO).
[0060] e) Group V oils are all other base stocks not included in
Group I, II, III, or IV. TABLE-US-00001 Property Test Method
Saturates ASTM D2007 Viscosity Index ASTM D2270 Sulfur ASTM
D4294
[0061] Preferably the volatility of the oil of lubricating
viscosity, as measured by the Noack test (ASTM D5880), is less than
or equal to about 40%, such as less than or equal to about 35%,
preferably less than or equal to about 32%, such as less than or
equal to about 28%, more preferably less than or equal to about
16%. Preferably, the viscosity index (VI) of the oil of lubricating
viscosity is at least 100, preferably at least 110, more preferably
greater than 120.
[0062] In addition to the VI improver and LOFI, a fully formulated
lubricant can generally contain a number of other performance
improving additives selected from ashless dispersants,
metal-containing, or ash-forming detergents, antiwear agents,
oxidation inhibitors or antioxidants, friction modifiers and fuel
economy agents, and stabilizers or emulsifiers. Conventionally,
when formulating a lubricant, the VI improver and/or VI improver
and LOFI, will be provided to the formulator in one concentrated
package, and combinations of the remaining additives will provided
in one or more additional concentrated packages, oftentimes
referred to as DI (dispersant-inhibitor) packages.
[0063] Dispersants useful in the context of the present invention
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 of the present invention 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.
[0064] Preferred dispersant compositions for use with the VI
improving copolymers of the present invention are
nitrogen-containing dispersants derived from
polyalkenyl-substituted mono- or dicarboxylic acid, anhydride or
ester, which dispersant has a polyalkenyl moiety with a number
average molecular weight of from about 1500 to 3000, preferably
from about 1800 to 2500. Further preferable, are succinimide
dispersants derived from polyalkenyl moieties with a number average
molecular weight of from about 1800 to 2500 and from about 1.2 to
about 1.7, preferably from greater than about 1.3 to about 1.6,
most preferably from greater than about 1.3 to about 1.5 functional
groups (mono- or dicarboxylic acid producing moieties) per
polyalkenyl moiety (a medium functionality dispersant).
Functionality (F) can be determined according to the following
formula:
F.dbd.(SAP.times.M.sub.n)/((112,200.times.A.I.)-(SAP.times.98))
wherein SAP is the saponification number (i.e., the number of
milligrams of KOH consumed in the complete neutralization of the
acid groups in one gram of the succinic-containing reaction
product, as determined according to ASTM D94); M.sub.n is the
number average molecular weight of the starting olefin polymer; and
A.I. is the percent active ingredient of the succinic-containing
reaction product (the remainder being unreacted olefin polymer,
succinic anhydride and diluent).
[0065] Generally, each mono- or dicarboxylic acid-producing moiety
will react with a nucleophilic group (amine, alcohol, amide or
ester polar moieties) and the number of functional groups in the
polyalkenyl-substituted carboxylic acylating agent will determine
the number of nucleophilic groups in the finished dispersant.
[0066] 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 succinyl groups in
the PIBSA to primary amine groups in the polyamine reactant.
[0067] The dispersant(s) are preferably non-polymeric (e.g., are
mono- or bis-succinimides). The dispersant(s) of the present
invention can be borated by conventional means, as generally taught
in U.S. Pat. Nos. 3,087,936, 3,254,025 and 5,430,105. Boration of
the dispersant is readily accomplished by treating an acyl
nitrogen-containing dispersant with a boron compound such as boron
oxide, boron halide boron acids, and esters of boron acids.
[0068] The dispersant or dispersants can be present in an amount
sufficient to contribute at least 0.08 wt. % of nitrogen,
preferably from about 0.10 to about 0.18 wt. %, more preferably
from about 0.115 to about 0.16 wt. %, and most preferably from
about 0.12 to about 0.14 wt. % of nitrogen to the lubricating oil
composition.
[0069] Additional additives that may be incorporated into the
compositions of the invention to enable particular performance
requirements to be met are detergents, metal rust inhibitors,
corrosion inhibitors, oxidation inhibitors, friction modifiers,
anti-foaming agents, anti-wear agents and pour point depressants.
Some are discussed in further detail below.
[0070] Metal-containing or ash-forming detergents function both as
detergents to reduce or remove deposits and as acid neutralizers or
rust inhibitors, thereby reducing wear and corrosion and extending
engine life. Detergents generally comprise a polar head with a long
hydrophobic tail, with the polar head comprising 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.
[0071] 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 and may be prepared in accordance with known
techniques by first forming a dihydrocarbyl dithiophosphoric acid
(DDPA), usually by reaction of one or more alcohol or a phenol with
P.sub.2S.sub.5 and then neutralizing the formed DDPA with a zinc
compound. For example, a dithiophosphoric acid may be made by
reacting mixtures of primary and secondary alcohols. Alternatively,
multiple dithiophosphoric acids can be prepared where the
hydrocarbyl groups on one are entirely secondary in character and
the hydrocarbyl groups on the others are entirely primary in
character. To make the zinc salt, any basic or neutral zinc
compound could be used but the oxides, hydroxides and carbonates
are most generally employed. Commercial additives frequently
contain an excess of zinc due to the use of an excess of the basic
zinc compound in the neutralization reaction.
[0072] 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,
phosphorous esters, metal thiocarbamates, oil soluble copper
compounds as described in U.S. Pat. No. 4,867,890, and
molybdenum-containing compounds and aromatic amines.
[0073] Known friction modifiers include oil-soluble
organo-molybdenum compounds. Such organo-molybdenum friction
modifiers also provide antioxidant and antiwear credits to a
lubricating oil composition. As an example of such oil soluble
organo-molybdenum compounds, there may be mentioned the
dithiocarbamates, dithiophosphates, dithiophosphinates, xanthates,
thioxanthates, sulfides, and the like, and mixtures thereof.
Particularly preferred are molybdenum dithiocarbamates,
dialkyldithiophosphates, alkyl xanthates and
alkylthioxanthates.
[0074] Other known friction modifying 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.
[0075] Foam control can be provided by an antifoamant of the
polysiloxane type, for example, silicone oil or polydimethyl
siloxane.
[0076] 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.
[0077] It may also be necessary to include an additive which
maintains the stability of the viscosity of the blend. Thus,
although polar group-containing additives achieve a suitably low
viscosity in the pre-blending stage it has been observed that some
compositions increase in viscosity when stored for prolonged
periods. Additives which are effective in controlling this
viscosity increase include the long chain hydrocarbons
functionalized by reaction with mono- or dicarboxylic acids or
anhydrides which are used in the preparation of the ashless
dispersants as hereinbefore disclosed.
[0078] Representative effective amounts of such additional
additives, when used in crankcase lubricants, are listed below:
TABLE-US-00002 Mass % ADDITIVE Mass % (Broad) (Preferred) Ashless
Dispersant 0.1-20 1-8 Metal Detergents 0.1-15 0.2-9 Corrosion
Inhibitor 0-5 0-1.5 Metal Dihydrocarbyl Dithiophosphate 0.1-6 0.1-4
Antioxidant 0-5 0.01-2 Pour Point Depressant 0.01-5 0.01-1.5
Antifoaming Agent 0-5 0.001-0.15 Supplemental Antiwear Agents 0-1.0
0-0.5 Friction Modifier 0-5 0-1.5 Basestock Balance Balance
[0079] Fully formulated passenger car diesel engine lubricating oil
(PCDO) compositions of the present invention preferably have a
sulfur content of less than about 0.4 mass %, such as less than
about 0.35 mass %, more preferably less than about 0.03 mass %,
such as less than about 0.15 mass %. Preferably, the Noack
volatility of the fully formulated PCDO (oil of lubricating
viscosity plus all additives) will be no greater than 13, such as
no greater than 12, preferably no greater than 10. Fully formulated
PCDOs of the present invention preferably have no greater than 1200
ppm of phosphorus, such as no greater than 1000 ppm of phosphorus,
or no greater than 800 ppm of phosphorus. Fully formulated PCDOs of
the present invention preferably have a sulfated ash (SASH) content
of about 1.0 mass % or less.
[0080] Fully formulated heavy duty diesel engine (HDD) lubricating
oil compositions of the present invention preferably have a sulfur
content of less than about 1.0 mass %, such as less than about 0.6
mass % more preferably less than about 0.4 mass %, such as less
than about 0.15 mass %. Preferably, the Noack volatility of the
fully formulated HDD lubricating oil composition (oil of
lubricating viscosity plus all additives) will be no greater than
20, such as no greater than 15, preferably no greater than 12.
Fully formulated HDD lubricating oil compositions of the present
invention preferably have no greater than 1600 ppm of phosphorus,
such as no greater than 1400 ppm of phosphorus, or no greater than
1200 ppm of phosphorus. Fully formulated HDD lubricating oil
compositions of the present invention preferably have a sulfated
ash (SASH) content of about 1.0 mass % or less.
[0081] This invention will be further understood by reference to
the following examples. All weight percents expressed herein
(unless otherwise indicated) are based on active ingredient (AI)
content of the additive, and/or upon the total weight of any
additive-package, or formulation which will be the sum of the AI
weight of each additive plus the weight of total oil and/or
diluent.
EXAMPLES
Example 1
[0082] Using a Group II base oil and a commercial additive package
(DI package) containing dispersant, detergent antioxidant, antiwear
agent (ZDDP), and antifoamant, an the VI improvers identified
below, a series of lubricants were blended to meet the J-300
viscosity requirements for the 15W-40 viscosity grade. All the oils
were formulated as shown to have the same kinematic viscosity at
100.degree. C. (kv.sub.100). In the following Table 1, all numbers
represent mass % relative to the total mass of the exemplified
compositions.
VII-1 is a commercially available isoprene/styrene diblock
copolymer having a styrene content of 35 mass %, and a number
average molecular weight (Mn) of 130,000 (6.00 mass % A.I.).
VII-2 is a commercially available amorphous OCP having an
ethylene-derived content of 49 mass % and a number average
molecular weight (Mn) of 59,500 (9.50 mass % A.I.).
[0083] VII-3 is a commercially available semicrystalline OCP having
an ethylene-derived content of 59.9 mass % and a number average
molecular weight (Mn) of 86,700 (7.65 mass % A.I.). TABLE-US-00003
TABLE 1 Component/ Example Comp. 1 Comp. 2 Comp. 3 Comp. 4 Inv. 1
Group II Oil 72.1 72.1 72.1 72.1 72.1 DI Package 14.7 14.7 14.7
14.7 14.7 LOFI 0.2 0.2 0.2 0.2 0.2 VII-1 13.0 -- -- 8.5 8.7 VII-2
-- -- 13.0 -- 4.2 VII-3 -- 13.0 -- 4.5 --
[0084] The soot-dispersing performance of the exemplified
formulations was determined in a carbon black bench test (CBBT). In
the CBBT, the ability of a finished oil sample to disperse carbon
black is evaluated by mixing the finished oil samples with
increasing amounts of carbon black, stirring the samples overnight
at 90.degree. C., and evaluating the samples for viscosity and
index using a rotational viscometer. The shear rate of the
rotational viscometer is varied up to 300 sec.sup.-1 and a plot of
shear vs. log viscosity is obtained. If the viscosity is Newtonian,
the slope of the plot (index) approaches unity, indicating that the
soot remains well dispersed. If the index becomes significantly
less than unity, there is shear thinning, which is indicative of
poor soot dispersancy. The results achieved with the exemplified
samples are tabulated below, in Table 2a and Table 2b.
TABLE-US-00004 TABLE 2a k.sub.v100 CB (%)/Example Comp. 1 Comp. 2
Comp. 3 Comp. 4 Inv. 1 6 29.17 27.95 46.10 30.52 30.10 8 48.55
43.09 49.57 65.80 36.58 12 475.11 283.88 189.64 908.42 98.42
[0085] TABLE-US-00005 TABLE 2b Index CB (%)/Example Comp. 1 Comp. 2
Comp. 3 Comp. 4 Inv. 1 6 0.937 0.973 0.514 0.907 0.924 8 0.773
0.884 0.718 0.617 0.971 12 0.072 0.188 0.321 0.123 0.724
[0086] The soot-dispersing properties of isoprene/styrene diblock
copolymers are known and confirmed by the excellent results
achieved with Comp. 1. Surprisingly, soot dispersing performance of
the material containing a blend of the isoprene/styrene diblock
copolymer with the crystalline OCP, is far worse than the material
containing the crystalline OCP alone (compare results with Comp. 4
with those of Comp. 2). In contrast, the use of a blend of the
isoprene/styrene diblock copolymer with the amorphous OCP results
in improved soot dispersancy compared to each of the
isoprene/styrene diblock copolymer and amorphous OCP alone (compare
results with Inv. 1 with those of Comp. 1 and Comp. 3).
[0087] Table 3, below, indicates the polymer content and properties
of the above-samples are shown below, in Table 3. TABLE-US-00006
TABLE 3 Comp. 12 Comp. 2 Comp. 3 Comp. 4 Inv. 1 Solid Polymer %
0.78 0.52 0.64 0.69 0.75 Kv100 (cSt) 14.43 14.42 14.59 14.65 14.71
CCS @ -30.degree. C. (cP) 5428 5248 5814 5495 5700 MRV @
-30.degree. C. (cP) 16737 14158 18314 16240 18321 MRV @ -30.degree.
C. (YS) <35 <35 <35 <35 <35 30 cycle KO shear
kv.sub.100 (cSt) 13.8 12.53 12.65 13.36 13.49 .DELTA. kv.sub.100
0.63 1.89 1.94 1.29 1.22
[0088] As is shown, while the blend of the isoprene/styrene diblock
copolymer and the amorphous OCP requires less polymer to meet the
target k.sub.v100 relative to the use of the isoprene/styrene
diblock copolymer alone, and therefore has an improved thickening
efficiency, the thickening efficiency of a blend of crystalline OCP
and isoprene/styrene diblock copolymer is inferior to that of the
crystalline OCP, alone. Further, the blends of the present
invention are shown to provide acceptable SSI (see
.DELTA.Kv100).
[0089] The disclosures of all patents, articles and other materials
described herein are hereby incorporated, in their entirety, into
this specification by reference. A description of a composition
comprising, consisting of, or consisting essentially of multiple
specified components, as presented herein and in the appended
claims, should be construed to also encompass compositions made by
admixing said multiple specified components. The principles,
preferred embodiments and modes of operation of the present
invention have been described in the foregoing specification. What
applicants submit is their invention, 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 invention.
* * * * *