U.S. patent application number 12/384402 was filed with the patent office on 2010-10-07 for lubricant composition containing ethylene-alpha olefin copolymer viscosity modifier.
Invention is credited to Willie Allan Givens, JR., Margaret May-Som Wu.
Application Number | 20100256026 12/384402 |
Document ID | / |
Family ID | 42826683 |
Filed Date | 2010-10-07 |
United States Patent
Application |
20100256026 |
Kind Code |
A1 |
Wu; Margaret May-Som ; et
al. |
October 7, 2010 |
Lubricant composition containing Ethylene-Alpha Olefin Copolymer
viscosity modifier
Abstract
Provided are lubricant compositions containing
ethylene/.alpha.-olefin copolymer viscosity modifiers which impart
unique viscometrics in high VI/low aromatics base stocks for engine
oil applications. In one form, the lubricant compositions include a
blend of Group I to Group V base stocks, or mixtures thereof, and
an ethylene/.alpha.-olefin copolymer made from ethylene with one or
more .alpha.-olefin, wherein the .alpha.-olefin has from 3 to 18
carbon atoms and the ethylene/.alpha.-olefin copolymer has a number
average molecular weight between 800 and 20,000 and a molecular
weight distribution of less than 3.0.
Inventors: |
Wu; Margaret May-Som;
(Skillman, NJ) ; Givens, JR.; Willie Allan;
(Williamstown, NJ) |
Correspondence
Address: |
ExxonMobil Research & Engineering Company
P.O. Box 900, 1545 Route 22 East
Annandale
NJ
08801-0900
US
|
Family ID: |
42826683 |
Appl. No.: |
12/384402 |
Filed: |
April 3, 2009 |
Current U.S.
Class: |
508/110 |
Current CPC
Class: |
C10M 143/06 20130101;
C10N 2030/02 20130101; C10N 2020/04 20130101; C10M 2205/0285
20130101; C10M 2205/022 20130101; C10M 143/08 20130101; C10N
2070/00 20130101; C10M 2205/022 20130101; C10M 2205/026 20130101;
C10M 2205/022 20130101; C10M 2205/028 20130101 |
Class at
Publication: |
508/110 |
International
Class: |
C10M 169/00 20060101
C10M169/00 |
Claims
1. A lubricant composition comprising a blend of Group I to Group V
base stocks, or mixtures thereof, and an ethylene/.alpha.-olefin
copolymer made from ethylene with one or more .alpha.-olefin,
wherein the .alpha.-olefin has from 3 to 18 carbon atoms and the
ethylene/.alpha.-olefin copolymer has a number average molecular
weight between 800 and 20,000 and a molecular weight distribution
of less than 3.0.
2. The lubricant composition of claim 1, wherein the
ethylene/.alpha.-olefin copolymer comprises between 10 wt % and 45
wt % ethylene content.
3. The lubricant composition of claim 1, comprising between 1 wt %
to 20 wt % of the ethylene/.alpha.-olefin copolymer.
4. The lubricant composition of claim 3, comprising between 2 to
15% of the ethylene/.alpha.-olefin copolymer.
5. The lubricant composition of claim 1, wherein the
ethylene/.alpha.-olefin copolymer has a number average molecular
weight ranging from 2000 to 10,000.
6. The lubricant composition of claim 5, wherein the
ethylene/.alpha.-olefin copolymer has a number average molecular
weight ranging from 3000 to 8000.
7. The lubricant composition of claim 6, wherein the
ethylene/.alpha.-olefin copolymer has a number average molecular
weight ranging from 3000 to 6000.
8. The lubricant composition of claim 1, wherein the
ethylene/.alpha.-olefin copolymer is made with metallocene
catalysts.
9. The lubricant composition of claim 1, wherein the base stock is
a Group IV base stock.
10. The lubricant composition of claim 1, wherein the base stock is
a Group V base stock.
11. The lubricant composition of claim 1, wherein the base stock is
a mixture of a Group IV base stock and a Group V base stock.
12. The lubricant composition of claim 1, wherein the
ethylene/.alpha.-olefin copolymer is a liquid ethylene/1-butene
copolymer.
13. The lubricant composition of claim 3, wherein the
ethylene/.alpha.-olefin copolymer is a liquid ethylene/1-butene
copolymer.
14. The lubricant composition of claim 1, wherein the
ethylene/.alpha.-olefin copolymer has a molecular weight
distribution of less than 2.5.
15. The lubricant composition of claim 14, wherein the
ethylene/.alpha.-olefin copolymer has a molecular weight
distribution of less than 2.0.
16. The lubricant composition of claim 1, wherein the composition
has a high temperature shear viscosity (HTHS) according to ASTM
D4683 of greater than 2.5858.times.Ln(100.degree. C. Kv, in
cS)-2.6738.
17. The lubricant composition of claim 1, wherein the composition
has a high temperature shear viscosity (HTHS) according to ASTM
D4683 of at least 3.5 cP and a mini rotary viscosity (MRV) at
-40.degree. C. according to ASTM D4684 of less than 15,000 cP.
18. The lubricant composition of claim 1, wherein the composition
has a MRV viscosity at -40.degree. C. according to ASTM D4684 of
less than 1.838.8.times.e.sup.(0.5923.times.(HTHS vis in cP)).
19. The lubricant composition of claim 1, wherein the composition
has a high temperature shear viscosity (HTHS) according to ASTM
D4683 of at least 2.9 cP and a mini rotary viscosity (MRV) at
-40.degree. C. according to ASTM D4684 of less than
1.838.8.times.e.sup.(0.5923.times.(HTHS vis in cP)).
20. The lubricant composition of claim 1, wherein the composition
has a high temperature shear viscosity (HTHS) according to ASTM
D4683 of at least 2.9 cP and a mini rotary viscosity (MRV) at
-40.degree. C. according to ASTM D4684 of less than 26,000 cP.
21. The lubricant composition of claim 1, wherein the composition
has an HTHS of at least 2.6 cP and a kinematic viscosity at
100.degree. C. of less than 16 cSt.
22. The lubricant composition of claim 21, wherein the
ethylene/.alpha.-olefin copolymer is a liquid ethylene/1-butene
copolymer.
23. The lubricant composition of claim 22, wherein the
ethylene/1-butene copolymer comprises between 19 wt % and 45 wt %
ethylene content.
24. The lubricant composition of claim 23, wherein the
ethylene/1-butene copolymer has a number average molecular weight
between 2000 and 6,000 and a molecular weight distribution of less
than 2.5.
25. The lubricant composition of claim 1, further comprising
lubricant additives selected from viscosity index improvers,
corrosion inhibitors, dispersants, oxidation inhibitors,
detergents, rust inhibitors, antiwear agents, anti-foaming agents,
flow improvers, friction modifiers, seal swellants, and
combinations thereof.
26. The lubricant composition of claim 12 including less than 30 wt
% of the ethylene-1-butene copolymer.
27. The lubricant composition of claim 26 including between 1 wt %
and 20 wt % of the ethylene-1-butene copolymer.
Description
FIELD
[0001] This disclosure relates to lubricant compositions containing
ethylene/.alpha.-olefin copolymer viscosity modifiers which impart
unique viscometrics in high VI/low aromatics base stocks for engine
oil applications.
BACKGROUND
[0002] Multi-grade engine oils, derived from a combination of low
viscosity basestocks and high molecular weight thickeners,
viscosity index improvers, and other components have been used for
a long time. Synthetic engine oils based on polyalphaolefins (PAOs)
have been shown to demonstrate performance benefits together with
cost effectiveness in automotive and other engine applications. In
these synthetic oils, as with conventional oils of mineral origin,
the viscosity-temperature relationship of the oil is one of the
critical criteria which must be considered when selecting the
lubricant for a particular application. The viscosity requirements
for qualifications as multi-grade engine oils are described by the
SAE Engine Oil Viscosity Classification-SAE J300.
[0003] The low temperature (W) viscosity requirements are
determined by two tests, 1. ASTM D5293, Method of Test for Apparent
Viscosity of Motor Oils at Low Temperature Using the Cold Cranking
Simulator (CCS), and 2. ASTM D4684, Standard Test Method for
Determination of Yield Stress and Apparent Viscosity of Engine Oils
at Low Temperature. Higher temperature viscosity is measured
according to 1. ASTM D445 (at 100.degree. C.), Method of Testing
for Kinematic Viscosity of Transparent and Opaque Liquids, and 2.
ASTM D4683 (at 150.degree. C.), Standard Test Method for Measuring
Viscosity at High Shear Rate and High Temperature by Tapered
Bearing Simulator. Table 1 below outlines the high and low
temperature requirements for the recognized SAE grades for engine
oils.
TABLE 1
[0004] SAE VISCOSITY GRADES FOR annE OILS ( ).(2) (S4E MOO, Revised
May2004)
[0005] Lo.v-Temperatm (.degree. C.) LoN-Shezr-Karts Lcw-Shear-Rate
Low-Terperatre (.degree. C.) Rtnoirg Viscosity.degree. ilnematic
Viscosity(5) Knernabc Visccsibt liyi-Shear-Rate SAE Mscosity
Crarking Mscosit?, rrPas Mac with ND Yield Stress.degree. (rrrr?/s)
at 100.degree. C. (rrm.sup.2/s) at 100.degree. C. Viscosity(6)
(rPas) at Grade rrPas Mac Mn MFK 150.degree. C. Mn
[0006] ON 6200 at -35 60,000 at -40 as 9/V 6330 at -30 60,000 at
-35 38 104 7000 at -25 60,000 at -30 4.1 15W 7000 at -20 60,000 at
-25 5.6 23/V 9530 at -15 60,000 at -20 5.6 2S/V 13,000 at -10
60,000 at -15 9.3 5.6<9.3 26 9.3<125 2.9 29 (OW 40, 5VN40,
and 125<16.3 101N40 grades)37 (19/V40, 23N40, 12.5<16.3
29/V40, 40 grades) 16.3<21.9 37 21.9<26.1 37
[0007] Notes: 1 mPas=1 cP; 1 mm.sup.2/s=1 cSt All values are
critical specifications as defined by ASTM D3244 (Section 3); with
95% confidence that ATV meets/exceeds specification (FIG. 2) ASTM D
5293-Automated measurement, with reproducibility R=7.3% mean
[0008] ASTM D 4684: Note that the presence of any yield stress
detectable by this method constitutes a failure regardless of
viscosity.
ASTM D 445
[0009] ASTM D 4883 or CEC L-36-A-90 (ASTM D4741). If method ASTM D
5481 Is used to determine High Shear Rate Viscosity, the 95% high
confidence limits must be recalculated using Reproducibility=5.4%
of the mean.
[0010] In addition to the viscosity temperature relationship, other
properties are, of course, required for an engine oil including
resistance to oxidation under the high temperatures encountered in
the engine, resistance to hydrolysis in the presence of the water
produced as a combustion product (which may enter the lubricating
circulation system as a result of ring blow-by) and since the
finished oil is a combination of base stock together with
additives, these properties should be achieved in the final,
finished lubricant so that it possesses the desired balance of
properties over its useful life.
[0011] In recent years, considerable attention has been given to
the tribological behavior of lubricants under conditions of high
shear rate and high pressure. At high shear rates, as in a
lubrication contact zone, considerable shear thinning may occur,
which results in a decrease in the thickness of the lubricant film
separating the relatively moving surfaces with the possibility that
inadequate film thickness may be maintained under these conditions.
As a counter to this tendency, it would be desirable to provide
lubricant compositions which can function effectively under high
temperature conditions and which possess good rheological
properties to provide adequate film thickness and wear protection
by resisting shear thinning under conditions of high temperature
and high shear rate as well as high contact pressure, and good low
temperature pumpability to ensure adequate lubrication on low
temperature engine startup.
[0012] The gasoline and diesel engine manufacturers in North
America, Europe and Asia Pacific demand lubricants of increasingly
higher quality and higher performance. Both the North American and
European automobile manufacturers associations are regularly
introducing new performance categories that simultaneously reflect
and stimulate improvements in lubricant quality and performance.
Key performance areas are fuel economy, longer drain intervals with
extended performance retention, better soot handling, lower
emissions, and improved low-temperature performance. Several of
these performance features push the industry to use basestocks with
lower viscosity, better oxidation stability, lower volatility,
higher saturates, lower sulphur, lower nitrogen, and lower
aromatics.
[0013] In particular, reduced vehicle emissions are partially
achieved by improved fuel economy and better low-temperature
starting capability (C. J. May, J. J. Habeeb, A. M. White,
Lubrication Engineering, 43 (7), 557-567), both of which lower fuel
consumption and consequently reduce gaseous emissions.
Low-viscosity SAE 0W-XX (where XX=40 or lower) grade lubricants can
demonstrate both of these performance characteristics. Relative
improvements in fuel economy can be achieved by low-viscosity
lubricants compared to a typical high-viscosity lubricant such as
SAE 20W-50 (fuel economy improvement equal to 0.44% versus SAE 40
grade reference lubricant). For example, an SAE 0W-30 viscosity
grade can achieve over 2.51% fuel economy improvement versus the
same reference lubricant.
[0014] Many European engine builders typically recommend oils which
have a minimum high temperature shear viscosity (HTHS) of 3.5 cP,
measured according to ASTM D4683. This is required for bearing
protection in engines which are capable of high power output under
high load conditions.
[0015] However, for lower viscosity multigrade oils (as defined by
the SAE J300-99 standard), formulating oils with an HTHS viscosity
of 3.5 cP minimum typically results in kinematic viscosity at
100.degree. C. (Kv.sub.100) very close to the upper limit for
certain viscosity grades. For example, an SAE 0W-30 or 5W-30 oil
with an HTHS viscosity of 3.5 cP will typically have a Kv.sub.100
of 12 cSt or higher, while the Kv.sub.100 specification for SAE 30
ranges from 9.3 cSt minimum to 12.5 cSt maximum.
[0016] Various combinations of additives with lubricants have been
used in the past for the improvement of lubricant properties and in
particular, the use of polymeric materials for altering the
viscosity or viscosity index of basestocks of mineral and synthetic
origin has been well known for a number of years. Polymeric
thickeners which are commonly used in the production of multi-grade
lubricants typically include hydrogenated styrene-isoprene block
copolymers, rubbers based on ethylene and propylene, polymers
produced by polymerization of esters of the acrylate or
methacrylate series, polyisobutylene and the like. These polymeric
thickeners are added to bring the viscosity of the base fluid up to
the level required for the desired grade (high temperature
specification) and possibly to increase the viscosity index of the
fluid, allowing for the production of multi-grade oils.
[0017] The use of high molecular weight thickeners and VI improvers
in the production of multi-grade lubricants has, however, some
serious drawbacks. First, these improvements are more sensitive to
oxidation than the basestocks in which they are used, which may
result in a progressive loss of viscosity index and thickening
power with use and frequently in the formation of unwanted
deposits. In addition, these materials tend to be sensitive to high
shear rates and stresses which can result in temporary or permanent
viscosity losses, or reduction of film thickness in bearings.
Temporary viscosity losses occurring from shear forces are the
result of the non-Newtonian viscometrics associated with the
solutions of high molecular weight polymers. As the polymer chains
align with the shear field under high shear rates, a decrease in
viscosity occurs, reducing film thickness and the wear protection
associated with the elastohydrodynamic film. By contrast, Newtonian
fluids maintain their viscosity regardless of shear rate. From the
point of view of lubricant performance at high temperatures and
under the influence of a shear rate condition, it would be
desirable to maintain Newtonian rheological properties for the
lubricant. High molecular weight thickeners are susceptible to
temporary or permanent shear thinning at high shear rate, resulting
in loss of viscosity under low or high temperature conditions.
Excessive shear thinning or loss of viscosity is undesirable in
certain applications such as bearings which rely primarily on oil
film thickness for protection.
[0018] U.S. Pat. No. 6,713,438, incorporated by reference herein in
its entirety, discloses high performance engine oils comprising a
blend of a low viscosity, liquid lubricant base stock with two
dissolved polymer components of different molecular weights. The
lower molecular weight polymer is highly viscoelastic in character
and is preferably an HVI-PAO. The use of the highly viscoelastic
low molecular weight polymer in combination with the higher
molecular weight thickener enables the production of very widely
cross-graded engine oils, especially oils with a low temperature
grading of 0W or better.
[0019] U.S. Pat. No. 7,022,784, incorporated by reference herein in
its entirety, discloses a liquid polymer suitable for use as a
lubricant base oil, which is produced by polymerizing ethylene and
at least one alpha-olefin using a metallocene catalyst to provide a
polymer which is then isomerized and hydrogenated to produce the
liquid polymer.
[0020] U.S. Published Patent Application No. 2003/0236177 A1,
incorporated by reference herein in its entirety, discloses a fluid
blend suitable for use as a lube base stock comprises two major
components: (A) a copolymer made from ethylene with one or more
alpha olefins, the copolymer (i) containing not more than 50 wt %
ethylene; (ii) having a number average molecular weight of from 400
to 10,000; and (iii) a molecular weight distribution <3; and (B)
a polyalphaolefin fluid or a hydroprocessed oil having a VI greater
than 80.
SUMMARY
[0021] A first embodiment of the present disclosure is directed to
a lubricant composition comprising a blend of Group I to Group VI
base stocks, or mixtures thereof, and an ethylene/.alpha.-olefin
copolymer made from ethylene with one or more .alpha.-olefin,
wherein the .alpha.-olefin has from 3 to 18 carbon atoms and the
ethylene/.alpha.-olefin copolymer has a number average molecular
weight between 800 and 20,000 and a molecular weight distribution
of less than 3.0.
[0022] In another embodiment, the copolymer of the lubricant
composition can comprise between 10 wt % and 45 wt % ethylene
content.
[0023] In another embodiment, the lubricant composition can
comprise between 1 wt % to 20 wt % of the ethylene/.alpha.-olefin
copolymer.
[0024] In another embodiment, the lubricant composition can
comprise between 2 to 15% of the ethylene/.alpha.-olefin
copolymer.
[0025] In another embodiment, the copolymer of the lubricant
composition has a number average molecular weight ranging from 2000
to 10,000.
[0026] In another embodiment, the copolymer of the lubricant
composition has a number average molecular weight ranging from 3000
to 8000.
[0027] In another embodiment, the copolymer of the lubricant
composition has a number average molecular weight ranging from 3000
to 6000.
[0028] Conveniently, the copolymer is made with metallocene
catalysts.
[0029] In another embodiment the lubricant composition base stock
is a Group III base stock.
[0030] In another embodiment the lubricant composition base stock
is a Group IV base stock.
[0031] In another embodiment the lubricant composition base stock
is a Group V base stock.
[0032] In another embodiment the lubricant composition base stock
is a Gas to Liquid (GTL) derived base stock.
[0033] In another embodiment the lubricant composition base stock
is a mixture selected from one or more of a Group III base stock,
Group IV base stock, Group V base stock and GTL base stock.
[0034] In another embodiment, the ethylene/.alpha.-olefin copolymer
is a liquid ethylene/1-butene copolymer.
[0035] In another embodiment, the ethylene/.alpha.-olefin copolymer
has a molecular weight distribution of less than 2.5.
[0036] In another embodiment, the ethylene/.alpha.-olefin copolymer
has a molecular weight distribution of less than 2.0.
[0037] In another embodiment, the lubricant composition has a high
temperature shear viscosity (HTHS) according to ASTM D4683 of
higher than 2.5858.times.Ln(100.degree. C. Kv, in cS)-2.6738.
[0038] In another embodiment, the lubricant composition has a high
temperature shear viscosity (HTHS) according to ASTM D4683 of at
least 3.5 cP and a mini rotary viscosity (MRV) at -40.degree. C.
according to ASTM D4684 of less than 15,000 cP.
[0039] In another embodiment, the lubricant composition has a MRV
viscosity at -40.degree. C. less than
1.838.8.times.e.sup.(0.5923.times.(HTHS vis in cP)).
[0040] In another embodiment, the lubricant composition has a high
temperature shear viscosity (HTHS) according to ASTM D4683 of at
least 2.9 cP and a mini rotary viscosity (MRV) at -40.degree. C.
according to ASTM D4684 of less than
1.838.8.times.e.sup.(0.5923.times.(HTHS vis in cP)).
[0041] In another embodiment, the lubricant composition has a high
temperature shear viscosity (HTHS) according to ASTM D4683 of at
least 2.9 cP and a mini rotary viscosity (MRV) at -40.degree. C.
according to ASTM D4684 of less than 26,000 cP.
[0042] In another embodiment, the lubricant composition has an HTHS
of at least 2.6 cP and a kinematic viscosity at 100.degree. C. of
less than 16 cSt.
[0043] In another embodiment, the copolymer of the lubricant
composition comprises between about 19 wt % and 45 wt % ethylene
content, has a number average molecular weight between about 2000
and about 6,000 and a molecular weight distribution of less than
about 2.5.
[0044] In another embodiment, the lubricant composition further
comprises lubricant additives selected from the group consisting of
viscosity index improvers, corrosion inhibitors, dispersants,
oxidation inhibitors, detergents, rust inhibitors, antiwear agents,
anti-foaming agents, flow improvers, friction modifiers, and seal
swellants.
BRIEF DESCRIPTION OF THE DRAWINGS
[0045] FIG. 1 is a graph of HTHS viscosity vs. 100.degree. C. Kv
for formulated lubricants.
[0046] FIG. 2 is a graph of MRV at -40.degree. C. vs. HTHS
Viscosity for formulated lubricants.
DETAILED DESCRIPTION
[0047] All numerical values in this disclosure are understood as
being modified by "about" or "approximately" the indicated value,
and take into account experimental error and variations that would
be expected by a person having ordinary skill in the art.
[0048] European engine builders recommend oils which have a minimum
high temperature shear viscosity (HTHS) of 3.5 cP, measured
according to ASTM D4683. This is required for bearing protection in
engines which are capable of high power output under high load
conditions.
[0049] However, for lower viscosity multigrade oils (as defined by
the SAE J300-99 standard), formulating oils with an HTHS viscosity
of 3.5 cP minimum typically results in kinematic viscosity at
100.degree. C. (Kv.sub.100) very close to the upper limit for
certain viscosity grades. For example, an SAE 0W-30 or 5W-30 oil
with an HTHS viscosity of 3.5 cP will typically have a Kv.sub.100
of 12 cSt or higher, while the Kv.sub.100 specification for SAE 30
ranges from 9.3 cSt minimum to 12.5 cSt maximum.
[0050] Another important characteristic for low viscosity engine
oils is low temperature pumpability, typically measured by the MRV
(mini rotary viscosity) test of ASTM D4684. The results of this
test are often reported in cP as measured at -40.degree. C. The
maximum MRV for a 0W lubricating oil is 60,000 cP.
[0051] Thus, formulating lubricating oils for both good low
temperature pumpability and good high temperature shear viscosity
in essence requires the formulator to address mutually exclusive
goals; i.e. to maintain low viscosity at very low temperatures
(e.g. at engine start-up), while also maintaining sufficiently high
viscosity at engine operating temperatures.
[0052] The present inventors have discovered that incorporation of
a minor amount of an ethylene/.alpha.-olefin liquid copolymer in a
lubricant composition containing one or more of a Group I to Group
V base stock permits formulation of SAE 5W-30 oils with 3.5 cP HTHS
viscosity at KV.sub.100 of less than 10.6 cSt. The
ethylene/.alpha.-olefin liquid copolymers of the present disclosure
impart excellent HTHS viscosity boost, while maintaining very
robust low temperature and Kv.sub.100 viscometrics.
[0053] One major component, component A, in the lubricant
composition of the present disclosure is a copolymer made from
ethylene with one or more alpha-olefins. Consequently, as used
herein, the term copolymer encompasses polymers containing 2, 3 or
more different monomer moieties. The copolymers in the blend of the
disclosure have a number average molecular weight of from 800 to
20,000 and a MWD<3. Importantly, the copolymer contains not more
than 50 wt % ethylene. The alpha-olefin moiety of the copolymer
will be derived from at least one or more C.sub.3, C.sub.4 or
higher alpha olefins.
[0054] Accordingly, suitable alpha-olefinic monomers include those
represented by the formula H.sub.2C.dbd.CHR.sub.1 wherein R.sub.1
is a straight or branched chain alkyl radical comprising 1 to 18
carbon atoms and preferably 1 to 10 carbon atoms, or alternatively
1 to 3 carbon atoms or alternatively 1 to 2 carbon atoms. When
R.sub.1 is a branched chain, the branch is preferred to be at least
two carbons away from the double bond.
[0055] The copolymers are prepared by copolymerizing a feed
containing ethylene and one or more alpha olefins in the weight
ratio of 60:40 to 5:95 in the presence of a metallocene catalyst
system. Metallocene catalyst systems are well known in the art and
mention is made of U.S. Pat. Nos. 6,030,930, 5,859,159,
incorporated herein by reference, for a description of metallocene
catalysts systems useful for producing the polymers from ethylene
and one or more alpha-olefins suitable for the lubricant fluid
blends of the present disclosure.
[0056] The copolymer is produced by polymerizing a reaction mixture
of ethylene and at least one additional alpha-olefin monomer in the
presence of a metallocene catalyst system, preferably in solution.
Optionally, hydrogen may be added to regulate the degree of
polymerization or molecular weight, and to reduce the amount of
unsaturation in the product. In such situations the amount of
hydrogen typically will be 0.1 mole % to 50 mole % based on the
amount of ethylene.
[0057] Any known solvent effective for such polymerization can be
used. For example, suitable solvents include hydrocarbon solvent
such as aliphatic, cycloaliphatic and aromatic hydrocarbons. The
preferred solvents are propane, n-butane, isobutane, pentane,
isopentane, hexane, isohexane, heptane, isoheptane, Norpar, Isopar,
benzene, toluene, xylene, alkylaromatic-containing solvents, or
mixture of these solvents.
[0058] The polymerization reaction may be carried out in a
continuous manner, such as in a continuous flow stirred tank
reactor where feed is continuously introduced into the reactors and
product removed therefrom. Continuously stirred tank reactor (CSTR)
method is more preferred because it produces the polymers with
narrow molecular weight distribution, lower MWD numbers and better
shear stability and better high temperature high shear rate
viscosity. CSTR is also more advantageous to produce products with
more homogenously randomly distributed alpha-olefin monomers along
the polymer backbone. Alternatively, the polymerization may be
conducted in a batch reactor, preferably equipped with adequate
agitation, to which the catalyst, solvent, and monomers are added
to the reaction and left to polymerize therein for a time
sufficient to produce the desired product.
[0059] Typical polymerization temperature for producing the
copolymers useful herein are in the range of 0.degree. C. to
300.degree. C., and preferably 25.degree. C. to 250.degree. C. at
pressures of 15 to 1500 psig, and preferably 50 to 1000 psig.
Typical hydrogen partial pressures are in the range of 0 psi to 300
psi, alternatively 1 psi to 200 psi, alternatively 2 psi to 100
psi, alternatively 15 to 50 psi. Key criteria of choosing H.sub.2
pressure is to minimize hydrogenation of feed olefins, to increase
catalyst productivity, to reduce degree of unsaturation in the
final polymers, to regulate polymer molecular weight at most
desirable range while maintaining narrow molecular weight
distribution (MWD).
[0060] The conditions under which the polymerization is conducted
will determine the degree of unsaturation in the resulting
copolymer. As is known in the art, the degree of unsaturation of a
polymer can be measured by bromine number. In the present
disclosure it is preferred that the copolymer have a bromine number
below 2 and more preferably in the range of 0 to 1. The degree of
unsaturation can also be determined by H-NMR method as described in
WO2007011459, WO2008010856.
[0061] In those instances where the product copolymer has a high
degree of unsaturation, such as when the copolymer product has a
viscosity less than 1000 cSt at 100.degree. C., the copolymer
preferably is hydrogenated to provide a final product having a
bromine number below 2. The hydrogenation may be carried out in a
batch mode or in continuous stir tank or in a continuous fixed bed
operation, using typical hydrogenation catalysts. Examples of the
hydrogenation catalysts are nickel on kieselguhr catalyst, Raney
Nickel catalyst, many commercial hydrotreating catalysts, such as
nickel, cobalt, molybdenum or tungsten on silica, silica-alumina,
alumina, zirconium support, etc., or supported Group VIIIB metals,
such as platinum, palladium, ruthenium and rhodium. The
hydrogenation conditions may range from room temperature to
300.degree. C. with hydrogen pressure from atmospheric pressure to
2000 psi for long enough residence time to reduce most or all of
the unsaturation. The unsaturation degree can be measured by
bromine number of iodine index. Preferably the bromine number of
the finished product should be below 2. The lower the bromine
number the better the oxidative stability. More preferably, the
reaction temperature, pressure, residence time, catalyst loading
all will be adjusted to achieve 0-1 bromine number.
[0062] In instances where the polymerization conditions favor the
formation of copolymers having a very low degree of unsaturation,
hydrogenation of the copolymer is not necessary and the copolymer
can be used directly in forming the lubricant blend.
[0063] Particularly beneficial copolymers are those comprising
between 10 to 45 wt % ethylene, or even between 19 to 45 wt %
ethylene. Likewise, particularly beneficial copolymers according to
the present disclosure have been determined to have number average
molecular weights between 2000 to 10,000, even between 3000 to
8000, and even between 3000 to 6000, with molecular weight
distributions (Mw/Mn) of less than 2.5, or even less than 2.0. A
particularly beneficial ethylene/.alpha.-olefin copolymer is made
from combinations of ethylene and 1-butene in the afore-mentioned
combination of monomer weight percentages, molecular weights and
MWD. Of particular interest are the polymers made from ethylene and
mixed C.sub.4 stream, which contains 5 to 95% of 1-butene in the
mixed butene stream. This mixed C.sub.4 stream is usually readily
available from refinery gas stream.
[0064] The copolymer is typically in the form of a viscous
liquid.
[0065] The other major component, component B, in the lubricant
composition of the present disclosure is a base oil selected from
Group I to Group V base oils and mixtures thereof. Advantageously,
the base oil component B is a Group III, Group IV, Group V base
oil, GTL base stock or a mixture of the two.
[0066] The amounts of ethylene/.alpha.-olefin copolymer and base
oils in the blends of fluid the present disclosure are not critical
and will depend on the intended use of the blend. In general the
amount of copolymer will constitute from 1 to 20 wt % of the blend.
Generally, it is preferred to be from 2 to 15 wt %, more preferably
from 5 to 15 wt %. If a too small amount of the polymer is used,
the blend will not have sufficient viscometrics. On the other hand,
if too much of the polymer is used, it may be more costly or the
blend viscosity may be too high for practical use.
[0067] The fluid blends of the present disclosure can be combined
with selected lubricant additives to provide lubricant
compositions. The additives listed below are typically used in such
amounts so as to provide their normal attendant functions. Typical
amounts for individual components are also set forth below.
TABLE-US-00001 Broad Wt % Preferred Wt % Viscosity Index Improver
1-12 1-4 Corrosion Inhibitor 0.01-3 0.01-1.5 Oxidation Inhibitor
0.01-5 0.01-1.5 Dispersant 0.1-10 0.1-5 Lube Oil Flow Improver
0.01-2 0.01-1.5 Detergents and Rust Inhibitors 0.01-6 0.01-3 Pour
Point Depressant 0.01-1.5 0.01-1.5 Antifoaming Agents 0.01-0.1
0.001-0.01 Antiwear Agents 0.001-5 0.001-2 Extreme Pressure
Additives 0.001-5 0.001-2 Seal Swellant 0.1-8 0.1-4 Friction
Modifiers 0.01-3 0.01-1.5 Fluid Blend of Disclosure .gtoreq.80%
.gtoreq.80%
[0068] When other additives are employed, it may be desirable,
although not necessary, to prepare additive concentrates comprising
concentrated solutions or dispersions of the dispersant, together
with one or more of the other additives to form an additive
mixture, referred to herein as an additive package whereby several
additives can be added simultaneously to the base stock to form the
lubricating oil composition. Dissolution of the additive
concentrate into the lubricating oil may be facilitated by solvents
and by mixing accompanied with mild heating, but this is not
essential. The concentrate or additive-package will typically be
formulated to contain the dispersant additive and optional
additional additives in proper amounts to provide the desired
concentration in the final formulation when the additive package is
combined with a predetermined amount of the fluid blend of the
disclosure.
[0069] All of the weight percents expressed herein (unless
otherwise indicated) are based on active ingredient (A.I.) content
of the additive, and/or upon the total weight of any
additive-package, or formulation which will be the sum of the A.I.
weight of each additive plus the weight of total oil or
diluent.
[0070] The composition of the disclosure may also include a co-base
stock to enhance lubricant performance or to improve additive
solubility in the base stock. Typically co-base stocks are selected
from polar fluids or Group V base stocks useful as lubricants.
[0071] Examples of these fluids include many types of esters,
alkylaromatics, and oil-soluble polyalkylene glycols. Typical
esters used in lubricant formulations include polyol esters,
adipate esters, sibacate esters, phthalate esters, sterates, etc.
Typical alkylaromatics used in lube formulation include alkylated
naphthalenes, alkylbenzenes, alkyltoluenes, detergent alkylate
bottoms, etc. Typical oil-soluble polyalkylene glycols include
poly-propylene oxides, poly-butylene oxides, etc. Such fluids may
be used in amounts of 1 wt % to 60 wt %, although amounts of 1 wt %
to 10 wt %, or 1 wt % to 20 wt % are preferred.
[0072] The following are examples of the present disclosure and are
not to be construed as limiting.
EXAMPLES
Illustrative Example 1
[0073] A copolymer was prepared in a continuous mode of operation.
In this reaction, polymer grade ethylene, polymer grade 1-butene
and polymer grade iso-butane solvent were charged into a 200 gallon
reactor after purification through molecular sieve and treatment by
injecting 50 ppm tri-t-butylaluminum. The feed rates for ethylene,
1-butene and iso-butane were 12, 120 and 180 lb/hour, respectively.
A catalyst solution, containing 5.times.10.sup.-6 g-mole/liter of
dimethylsilylbis (4,5,6,7 tetrahydro-indenyl) zirconium dichloride
and methyl-aluminoxane of 1/400 Zr/Al molar ratio in toluene, was
charged into the reactor at 13.5 ml/minute. The reactor temperature
was maintained 89.4.degree. C. and 95.6.degree. C., pressure
237-261 psi and average residence time 2 hours. The crude reaction
product was withdrawn from the reactor continuously and washed with
0.4 wt % sodium hydroxide solution followed with a water wash. A
viscous liquid product was obtained by devolitalization to remove
iso-butane solvent, light stripping at 66.degree. C./5 psig
followed by deep stripping at 140.degree. C./1 millitorr. The
residual viscous liquid was then hydro-finished at 200.degree. C.,
800-1200 psi H.sub.2 pressure with 2 wt % Ni-on-Kieselguhr catalyst
for eight hours. The hydrogenated product contained 34 wt %
ethylene content and had the following properties: 100.degree. C.
Kv=114.0 cS, 40.degree. C. Kv=1946.5 cS, VI=145 and pour
point=-24.degree. C. This copolymer had Mn of 2374 and MWD of
1.88.
Illustrative Example 2
[0074] This copolymer was prepared in a similar manner as in
Example 1, except that the feed rates for ethylene, 1-butene and
isobutane were 58, 120 and 283 lb/hour, and the reaction
temperature was between 98.3.degree. C. and 101.1.degree. C.,
pressure 290-300 psi and average residence time 1 hour. After
hydrofinishing, the residual viscous liquid contained 44 wt %
ethylene and had the following properties: 100.degree. C. Kv=149.9
cS, 40.degree. C. Kv=2418.4 cS, VI=164 and pour point=-24.degree.
C. This copolymer had Mn of 2660 and MWD of 1.76.
Illustrative Example 3
[0075] This copolymer was prepared in a similar manner as in
Example 1, except that the feed contained 40 wt % 1-butene, 11 wt %
ethylene and 49 wt % isobutane, the reaction temperature was
71.degree. C., and average residence time was 1 hour. After
hydrofinishing, the hydrogenated product contained 19 wt % ethylene
and had the following properties: 100.degree. C. Kv=1894 cS,
40.degree. C. Kv=42608 cS, VI=278 and pour point=-1.degree. C. This
copolymer had Mn of 5491 and MWD of 2.80.
Illustrative Example 4
[0076] This polymer was prepared in a similar manner as in Example
1, except that the feed contained 40 wt % 1-butene, 35 wt %
ethylene and 25 wt % isobutane, the reaction temperature was
93.3.degree. C., and average residence time was approximately 1
hour. After hydrofinishing, the viscous liquid contained 44.5 wt %
ethylene and had the following properties: 100.degree. C. Kv=1493
cS, 40.degree. C. Kv=49073 cS, VI=230 and pour point=5.degree. C.
This copolymer had Mn of 5664 and MWD of 2.76.
Formulation Examples
[0077] A core passenger vehicle engine oil formulation comprising a
mix of Group IV and Group V base oils and fixed additive treat rate
was used to compare the viscosity effects of commercially available
viscosity index improvers against those of EBC copolymers (EBC-1
and EBC-3) of the present disclosure. Formulation specifics and
testing data is set forth in Table 2, below.
TABLE-US-00002 TABLE 2 A B C D E F G H Wt % Components Additive
package 16.45 16.45 16.45 16.45 16.45 16.45 16.45 16.45 Base oil
78.55 73.55 68.55 78.55 73.55 68.55 78.55 73.55 VI Improver SV50 0
0 0 0 0 0 0 0 LZ Styrene-ester polymer 5 10 15 0 0 0 0 0 Shellvis
200 0 0 0 5 10 15 0 0 EBC-1* 0 0 0 0 0 0 5 10 EBC-3* 0 0 0 0 0 0 0
0 Total 100 100 100 100 100 100 100 100 Testing Results
Kv@100.degree. C., cS D445-5 10.92 16.2 23.06 10.24 15.17 22.17
8.39 10.88 HTHS vis, cP D4683 3.17 4.1 5.17 3.17 4.1 5.25 2.9 3.7
Av. MRV @ D4864-7 13349 23190 43643 15038 27208 46972 7651 12128
-40.degree. C. CCS@-30.degree. C., cP D5293-6 3210 4150 5550 3060
3620 4330 3570 5130 I J K L M N O Wt % Components Additive package
16.45 16.45 16.45 16.45 16.45 16.45 16.45 Base oil 68.55 78.55
73.55 68.55 74.52 71.52 60.05 VI Improver SV50 0 0 0 0 9 12 23.5 LZ
Styrene-ester polymer 0 0 0 0 0 0 0 Shellvis 200 0 0 0 0 0 0 0
EBC-1* 15 0 0 0 0 0 0 EBC-3* 0 5 10 15 0 0 0 Total 100 100 100 100
99.97 99.97 100 Testing Results Kv@100.degree. C., cS D445-5 16.28
8.2 10.32 14.83 8.8 9.75 13.5 HTHS vis, cP D4683 5.26 2.84 3.48
4.74 2.9 2.95 3.5 Av. MRV @ D4864-7 25402 7544 11588 24902 12700
13200 22600 -40.degree. C. CCS@-30.degree. C., cP D5293-6 9950 3530
5230 10200 2710 2950 3050 *The data highlighted in bold is that of
the present disclosure.
[0078] FIG. 1 illustrates high temperature high shear rate (HTHS)
viscosity versus kinematic viscosity at 100.degree. C. for
lubricants blended with different high molecular weight polymers.
EBC-1 and EBC-3 are shown to provide higher HTHS viscosity than
other polymers at any given kinematic viscosity, thus illustrating
superior film thickness of the EBC polymers at equal kinematic
viscosity. For example, EBC-1 used at 10 wt % in the finished oil
formulation allows an SAE 5W-30 oil to deliver film thickness under
high shear rate conditions equal to that of SAE 60 grade oils which
have a minimum HTHS viscosity requirement of 3.7 cSt minimum
according to SAE J300.
[0079] FIG. 2 illustrates MRV low temperature pumpability (at
-40.degree. C.) versus HTHS viscosity (at 150.degree. C.) for
lubricants blended with different high molecular weight polymers.
EBC-2 and EBC-3 are shown to provide lower MRV viscosities at any
given HTHS viscosity, thus illustrating superior low temperature
pumpability characteristics of the EBC polymers.
[0080] The data in Table 2 above indicate the ability to formulate
lubricating oil compositions which have HTHS viscosities
(.gtoreq.3.5 cP) typically specified by many European engine
builders, while robustly meeting KV.sub.100 limits for 30 weight
oils, and while concurrently having MRV @-40.degree. C. at levels
well below the upper limit for 0W oils.
[0081] Applicants have attempted to disclose all embodiments and
applications of the disclosed subject matter that could be
reasonably foreseen. However, there may be unforeseeable,
insubstantial modifications that remain as equivalents. While the
present invention has been described in conjunction with specific,
exemplary embodiments thereof, it is evident that many alterations,
modifications, and variations will be apparent to those skilled in
the art in light of the foregoing description without departing
from the spirit or scope of the present disclosure. Accordingly,
the present disclosure is intended to embrace all such alterations,
modifications, and variations of the above detailed
description.
[0082] All patents, test procedures, and other documents cited
herein, including priority documents, are fully incorporated by
reference to the extent such disclosure is not inconsistent with
this invention and for all jurisdictions in which such
incorporation is permitted.
[0083] When numerical lower limits and numerical upper limits are
listed herein, ranges from any lower limit to any upper limit are
contemplated.
* * * * *