Note: Descriptions are shown in the official language in which they were submitted.
WO 01/30947 CA 02388946 2002-04-24 PCT/US00/29395
INTERPOLYMERS CONTAINING LUBRICATING OIL COMPOSITION
FIELD OF THE INVENTION
The present invention pertains to lubricating oil compositions comprising
interpolymers containing (1) ethylene; (2) one or more vinylic monomers
selected
from the group consisting of aromatic. hindered aliphatic and cycloaliphatic
vinylic
monomers, and (3) one or more polymerizable C3 to C2o olefinic monomers. These
polymers serve as viscosity improving agents.
BACKGROUND OF THE INVENTION
The viscosity of lubricating oils, particularly the viscosity of mineral oil
based
lubricating oils, is generally dependent upon temperature. As the temperature
of the
oil is increased, the viscosity usually decreases.
The function of a viscosity improver in lubricating oil compositions is to
reduce the extent of the decrease in viscosity as the temperature is raised or
to reduce
the extent of the increase in viscosity as the temperature is lowered, or
both. Thus, a
viscosity improver ameliorates the change of viscosity of an oil containing it
with
changes in temperature. The fluidity characteristics of the oil are improved.
Viscosity improvers are usually polymeric materials and are often referred to
as viscosity index improvers. Many patents relating to viscosity improvers are
discussed by Ranney (Ed.), "Lubricant Additives", Noyes Data Coip. (1973), pp
93-
145.
A number of hydrogenated alkenylarene-conjugated dime intetpolymers are
known in the prior art to be effective viscosity index (VI) improvers for
lubricating
oils. U.S. Pat. Nos. 3.554,911 (Schiff et al.); 3,630,905 (Sorgo); and
3,77?.169
(Small et al. ) are concerned with the use of hydrogenated random butadiene-
styrene
copolymers as VI improvers for lubricating oils. These copolymers are prepared
by
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the copolymerization, using conventional techniques, of butadiene and styrene
in the
presence of a randomizing agent and subsequently, the copolymers are partially
hydrogenated.
U.S. Patent 2,336,195 (Sparks et al.) relates to improving viscosity
characteristics of hydrocarbon oils by addition of normal mono-olefin
polymers.
U.S. Patent 3,772,196 (St. Clair et al.) describes lubricating oils for
internal
combustion engines that have wide temperature operating characteristics. The
composition contains a combination of a 2-block copolymer comprising a first
block
of an alkenyl arene, e.g. styrene, and a second essentially completely
hydrogenated
polyisoprene block and certain pour point depressants in a lubricant stock
having
viscosity index of at least 85.
Many vinyl aromatic monomer-dime copolymers of the prior art are tapered
block copolymers. The interpolymers of the instant invention are random
interpolymers.
The generic class of materials covered by alpha-olefin/hindered vinylic
monomer substantially random interpolymers and including materials such as
ethylene/vinyl aromatic monomer interpolymers is known in the art. For
example,
substantially random ethylene/styrene interpolymers, including pseudo-random
interpolymers as described in EP 415815 A, offer a range of material
structures and
properties which makes them useful for varied applications, including the
compatibilization of blends of polyethylene and polystyrene as described in
U.S.
Patent 5,460,818. Random copolymers of aromatic vinyl monomer and an alpha-
olefin having 4 to 12 carbon atoms are described in U.S. Patent 5,244,996.
Interpolvmers of the type now found useful in the lubricating oil compositions
of this
invention are described in U.S. Patent 5,872,201. Other patent publications
provide
limited generic reference to terpolymers of ethylene/styrene/alpha-olefin
materials.
Examples in JP 07/278,230 are limited to 2 mole percent or less incorporation
of
styrene in ethylene/ alpha-olefin copolymers. None of these references teaches
the
use of such polymers as viscosity improving additives for lubricating oil
compositions.
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Although of utility in their own right, efforts continue to further expand the
applicability of these generic interpolymers into lubricating applications,
and
especially those based on alpha-olefin/vinylic aromatic monomers, such as
ethylene/styrene interpolymers. Lubricating applications include use of the
polymers
as viscosity improvers for lubricating oils and as thickeners for lubricating
greases.
Desired improved or superior characteristics to current state of the art
materials can
include, but are not limited to performance characteristics such as extended
temperature range of application and low temperature performance and improved
compatibility with a variety of oils of lubricating viscosity, especially
synthetic oils
and high viscosity index base stocks. The interpolymers used in the
lubricating oil
compositions of this invention are less costly compared to hydrogenated
vinylic
aromatic monomer-diene copolymers. The interpolymers of this invention provide
an
effective technology to address such needs.
SLTNIMARY OF THE INVENTION
The present invention relates to lubricating oil compositions comprising a
major amount of an oil of lubricating viscosity and a minor, viscosity
improving
amount, of a substantially random interpolymer resulting from polymerizing (1)
from
about 19.5 to about 98.5 mole percent of ethylene; (2) from about 0.5 to about
60
mole percent of one or more vinylic monomers selected from the group
consisting of
aromatic, hindered aliphatic, and cycloaliphatic vinylic monomers; and (3)
from about
1 to about 80 mole percent of one or more olefinic monomers having from 3 to
about
20 carbon atoms.
One aspect of the present invention pertains to lubricating oil compositions
comprising interpolymers comprising (1) from about 19.5 to about 98.5 mole
percent
of ethylene (2) from about 0.5 to about 60 mole percent of a vinylic monomer
selected
from the group consisting of aromatic and hindered aliphatic, and
cycloaliphatic
vinylic monomers, and (3) from about 1 to about 80 mole percent of one or more
C~
to CZO olefinic monomers.
In one embodiment, the interpolymers of the present invention can comprise
any three such monomers enumerated herein; these interpolymers can comprise
the
3
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WO 01/30947 PCT/US00/29395
three enumerated polymerizable monomers, with the third monomer (3) being one
C3
to CZO olefinic monomer.
The interpolymers of the present invention can be free of any component,
compound or substituent not specifically enumerated herein when desired. Also,
the
present invention can be free of any component, compound or substituent even
though
such component, compound or substituent was originally believed to be a part
of the
invention.
The interpolymers of the present invention provide an improvement in one or
more of the properties such as viscosity index in lubricating oils and
improved
compatibility with a wide variety of oils of lubricating viscosity, especially
high
viscosity index oils and particularly synthetic oils.
DETAILED DESCRIPTION OF THE INVENTION
The term "terpolymer" is used herein to indicate a polymer wherein three
different monomers are polymerized to make the terpolymer. The term
"interpolymer" is used herein to indicate a polymer wherein three or more
different
monomers are polymerized to make the interpolymer.
The term "substantially random" in the substantially random interpolymer
comprising ethylene, one or more vinylic aromatic monomers or hindered
aliphatic
vinylic monomers, and one or more C3 to Czo olefinic monomers as used herein
means that the distribution of the monomers of said interpolymer can be
described by
the Bernoulli statistical model or by a first or second order Markovian
statistical
model, as described by J. C. Randall in POLYMER SEQUENCE
DETERMINATION, Carbon-13 NMR Method, Academic Press, New York (1977),
2~ pp. 71-78. Preferably, the substantially random interpolymer does not
contain more
than 15 percent of the total amount of vinylic aromatic monomer in blocks of
vinylic
aromatic monomer of more than 3 units. More preferably, the interpolymer is
not
characterized by a high degree of either isotacticity or syndiotacticity. This
means
that in the Carbon-13 NMR spectrum of the substantially random interpolymer
the
peak areas corresponding to the main chain methylene and methine carbons
4
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representing either meso diad sequences or racemic diad sequences should not
exceed
75 percent of the total peak area of the main chain methylene and methine
carbons.
Any numerical values recited herein include all values from the lower value to
the upper value in increments of one unit provided that there is a separation
of at least
2 units between any lower value and any higher value. As an example, if it is
stated
that the amount of a component or a value of a process variable such as, for
example,
temperature, pressure, time and the like is, for example, from 1 to 90,
preferably from
20 to 80, more preferably from 30 to 70, it is intended that values such as 15
to 85, 22
to 68, 43 to 51, 30 to 32 etc. are expressly enumerated in this specification.
For
values which are less than one, one unit is considered to be 0.0001, 0.001,
0.01 or 0.1
as appropriate. These are only examples of what is specifically intended and
all
possible combinations of numerical values between the lowest value and the
highest
value enumerated are to be considered to be expressly stated in this
application in a
similar manner.
The interpolymers used in the lubricating oil compositions of the present
invention comprise at least three different monomers, (1) from about 19.5 to
about
98.5, preferably from about 25 to about 95, more preferably from about 30 to
about 94
mole percent of ethylene; (2) from about 0.~ to about 60, preferably from
about 1 to
about 55, more preferably from about 1 to about 50 mole percent of one or more
aromatic vinylic monomers or hindered aliphatic vinylic monomers, and (3) from
about 1 to about 80, preferably from about 4 to about 65, more preferably from
about
5 to about 50 mole percent of one or more C; to C2~ olefin monomers. It is to
be
understood that the total amount of (1), (2) and (3) is 100 mole percent.
The weight average molecular weight ( M W) of the interpolymers of the
present invention is usually b eater than about 10,000, preferably from about
50,000
to about 700,000, more preferably from about 80,000 to about 350,000.
Molecular
weights of the hydrocarbon polymer are determined using well known methods
described in the literature. Examples of procedures for determining the
molecular
weights are gel permeation chromatography (GPC) (also known as size-exclusion
chromatography) and vapor phase osmometry (VPO). These and other procedures
are
described in numerous publications including:
5
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WO 01/30947 PCT/US00/29395
P.J. Flory, "Principles of Polymer Chemistry", Cornell University Press
(1953), Chapter VII, pp. 266-316,
"Macromolecules, an Introduction to Polymer Science", F.A. Bovey and F.H.
Window, Editors, Academic Press (1979), pp. 296-312, and
W.W. Yau, J.J. Kirkland and D.D. Bly, "Modern Size Exclusion Liquid
Chromatography", John Wiley and Sons, New York, 1979.
Molecular weight values referred to herein are direct molecular weights
determined using GPC with multiangle light scattering and refractive index for
detection. Such procedures are described in the literature, for example in
Barth et al.,
Chemical Analysis, Vol. 113, "Modern Methods of Polymer Characterization",
John
Wiley & Sons, (1991). Other procedures that can be used include GPC employing
polystyrene standards.
It is particularly preferred that the interpolymer of this invention is a
terpolymer. Especially preferred is the terpolymer wherein component (2) is an
aromatic vinylic monomer, more preferably styrene, and component (3) is an
alpha
olefin having from 3 to about 12 carbon atoms, more preferably one or more
olefinic
monomers selected from the group consisting of propylene, butene-1, 4-methyl-1-
pentene, pentene-1, hexene-1 and octene-1.
The present invention particularly concerns the following terpolymers:
ethylene/styrene/propylene; ethylene/styrene/4-methyl-1-pentene;
ethylene/styrene/
hexene-1; ethylene/styrene/octene-1; and ethylene/styrene/1-butene.
Suitable alpha-olefins, or combinations of alpha-olefins, which can be
ern. ployed as olefinic monomers) (3) include for example, those containing
from 3 to
about 20, preferably from 3 to about 12, more preferably from 3 to about 8
carbon
atoms. Suitable olefinic monomers which can be employed as olefinic monomer(sj
(3) include strained ring olefins such as norbornene. Particularly suitable as
olefinic
monomers) (3) include propylene, 4-methyl-1-pentene, pentene-l, hexene-1,
octene-
1 and butene-1. The olefinic reactant (3) does not include hindered aliphatic
and
cycloaliphatic olefins as defined herein for reactant (2)
Suitable vinylic aromatic monomers for use as component (2) include, for
example, those represented by the following formula:
6
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Ar
( ~ H2)n
R1- C=CH2
wherein R' is selected from the group of radicals consisting of hydrogen and
hydrocarbyl groups, preferably alkyl or aryl groups, especially alkyl radicals
containing from 1 to about 4 carbon atoms and more preferably hydrogen or
methyl;
and Ar is a phenyl group or a phenyl group substituted with from 1 to 3
substituents
selected from the group consisting of halo, C1_4-alkyl, and Ci.~ haloalkyl;
and n has a
value from zero to about 6, preferably from zero to about 2, more preferably
zero.
Exemplary monovinylic aromatic monomers include styrene, vinyl toluene, alpha-
methylstyrene, t-butyl styrene, chlorostyrene, including all isomers of these
compounds, and the like. Particularly suitable such monomers include styrene
and
lower alkyl- or halogen-substituted derivatives thereof. Preferred monomers
include
styrene, alpha-methyl styrene, the lower alkyl- or phenyl-ring substituted
derivatives
of styrene, such as ortho-, meta-, and para-methylstyrene, the ring
halogenated
styrenes, para-vinyl toluene or mixtures thereof, and the like. A more
preferred
monovinylic aromatic monomer is styrene.
Suitable "hindered aliphatic or cycloaliphatic vinylic monomers" for use as
components (2) include addition polymerizable vinylic monomers corresponding
to
the following formula:
R'
R'- C=CHI
wherein R1 is selected from the group of radicals consisting of hydrogen and
hydrocarbyl groups, preferably alkyl or aryl groups, especially alkyl radicals
containing from 1 to about 4 carbon atoms and more preferably hydrogen or
methyl;
and R2 is a sterically bulky, aliphatic substituent of up to 20 carbons; or
alternatively
R1 and R'' together form a ring system. By the term "sterically bulky" it is
meant that
the monomer bearing this substituent is normally incapable of addition
polymerization
by standard Ziegler-Natta polymerization catalysts at a rate comparable with
ethylene
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WO 01/30947 PCT/US00/29395
polymetizations. Preferred hindered aliphatic or cycloaliphatic vinylic
monomers are
those in which one of the carbon atoms bearing ethylenic unsaturation is
tertiary or
quaternary substituted. Examples of such substituents include cyclic aliphatic
groups
such as cyclohexyl, cyclohexenyl, cyclooctenyl, or ring alkyl or aryl
substituted
derivatives thereof, tert-butyl, norbornyl, and the like. Most preferred
hindered
aliphatic or cycloaliphatic vinylic compounds are vinyl cyclohexane and the
various
isomeric vinyl-ring substituted derivatives of cyclohexene and substituted
cyclohexenes, and 5-ethylidene-2-norbornene. Especially suitable is vinyl
cyclohexane.
The substantially random interpolymers of the present invention can be
prepared as described in EP-A-0,416,815 (Stevens et al.) which is incorporated
herein
by reference in its entirety. Preferred operating conditions for such
polymerization
reactions are pressures from atmospheric up to 3000 atmospheres and
temperatures
from - 30° C to 200° C. Polymetizations and unreacted monomer
removal at
temperatures above the autopolymerization temperature of the respective
monomers
may result in formation of some amounts of homopolymer polymerization products
resulting from free radical polymerization. While preparing the substantially
random
intetpolymers of the present invention as will be desct-ibed hereinafter, an
amount of
atactic vinylic aromatic homopolymer may be formed due to homopolymerization
of
the vinylic aromatic monomer. However, NMR indicates polystyrene may be
present
in the styrene monomer and is not always generated during the polymerization
reaction. Thus, the presence of polystyrene in the polymer may be avoided by
use of
styrene monomer of suitable purity.
The presence of vinylic aromatic homopolymer is in general not desirable for
the purposes of the present invention, often resulting in hazy oil blends. The
vinylic
aromatic homopolymer may be separated from the interpolymer, if desired, by
extraction techniques such as selective precipitation from solution with a non-
solvent
for either the interpolymer or the vinylic aromatic homopolymer. For example,
a
polystyrene containing polymer is dissolved in hexane and coagulated in
acetone. For
the purpose of the present invention it is preferred that the copolymers of
this
invention are substantially free of vinylic aromatic homopolymer As used here,
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"substantially free" means the copolymer contains no amount of vinylic
aromatic
homopolymer that would cause objectionable haze or other incompatibility in a
lubricating oil composition. Preferably, the copolymer is free of vinylic
aromatic
homopolymer.
Examples of suitable catalysts and methods for preparing the substantially
random interpolymers of the present invention are disclosed in EP-A-416,815;
EP-A-514,828; U.S. Patent No. 5,721,185; U.S. Patent No. 5,470,993; as well as
U.S.
Patent Nos. 5,055,438; 5,057,475; 5,096,867; 5,064,802; 5,132,380; 5,189,192;
5,321,106; 5,347,024; 5,350,723; 5,374,696; 5,399,635; 5,556,928; 5,703,187
and
5,872,201, all of which patents and applications are incorporated herein by
reference.
The substantially random interpolymers of the present invention can also be
prepared by the methods described by Bradfute et al. in WO 95/32095; by
Pannell in
WO 94/00500; and in Plastics Technology, p. 25 (September 1992), all of which
are
incorporated herein by reference in their entirety. Further preparative
methods which
may be applicable for the interpolymers of the present invention have been
described
in the literature. Longo and Grassi (Makrornol. Chem., Volume 191, pages 2387
to
2396 [1990]) and D'Anniello et al. (Journal of Applied Polymer Science, Volume
58,
pages 1701-1706 [1995]) reported the use of a catalytic system based on
methylaluminoxane (MAO) and cyclopentadienyltitanium trichloride (CpTiCl3) to
prepare an ethylene-styrene copolymer. Xu and Lin (Polymer Preprints,
Am.Chem.Soc.,Div. Polym. Chem.) Volume 35, pages 686,687 [1994]) have reported
copolymerization using a TiCl4/NdCI~/Al(iBu)3 catalyst to give random
copolymers
of styrene and propylene. Lu et al. (Journal of Applied Polymer Science,
Volume 53,
pages 1453 to 1460 [1994]) have described the copolymerization of ethylene and
styrene using a TiCl4/NdCI~/MgCI~ /Al(Et)3 catalyst. Sernetz et al. (Macromol.
Chem.
Phys., v 197, pp 1071-1083, 1996) have described copolymerization of styrene
with
ethylene using rlb-(CS(CH~)4Si(CH3)~N(tert-C4H9))TiCI~/methylaluminoxane.
Another suitable method includes the method disclosed for the manufacture of
alpha -
olefin/vinyl aromatic monomer interpolymers such as propylene/styrene and
butene/styrene described in U.S. Pat. No. 5,244,996, assigned to Mitsui
Petrochemical
Industries Ltd. All of the above are incorporated herein by reference.
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Additives such as organic antioxidants (e.g., hindered phenols such as, for
example, IRGANOX~ 1010), phosphites (e.g., IRGAFOS~ 168)), both from Ciba
Geigy, LJV stabilizers, and the like can also be included in the
interpolymers, additive
concentrates and lubricating oil compositions of the present invention, to the
extent
that they do not interfere with the enhanced properties discovered by
Applicants.
The following examples are illustrative of the polymers used in the
lubricating
oil compositions of the invention, but are not to be construed as to limiting
the scope
of the invention in any manner. All temperatures are in degrees Celsius
(°C).
Polymerization:
In a typical polymerization dry hexane (see Table 1) is pressurized from a
stainless steel hold tank under nitrogen into a dry 1 gal (3.7 L) batch
reactor equipped
with a magnetically driven stirring mechanism. A heptane solution of
methylaluminoxane (120 g, 165.5 mL; 7 wt% Al), which contains 30 mole% iso-
butyl
groups, is then pressurized into the reactor under nitrogen. Freshly distilled
styrene
and a-olefin (see Tables 1-2) are added, and the homogeneous mixture is
thermostated at the desired temperature (see Table 1). Once the desired
temperature
is reached, the reactor is pressurized with the desired amount of ethylene
(see Tables
1-2). Finally, a heptane solution of methylaluminoxane (34.8 g, 47.7 mL; 7 wt%
Al),
which contains 30 mole% iso-butyl groups, is mixed with
~6-(CS(CH;)4Si(CH;)2N(tert-C4H9))TiCIZ (9.6 mg) to form a homogeneous
solution.
This solution is added to the reactor under nitrogen within 5 min of becoming
homogeneous. The polymerization reaction is terminated after a given period of
time
(see Table 1) by venting the ethylene from the reactor and pressurizing the
polymer
cement from the reactor under nitrogen into iso-propyl alcohol (2 L), to which
HCl
(15-25 mL; 18 M) has been added.
Polymer Purification:
The coagulated polymer is collected and rinsed with fresh iso-propyl alcohol
(1 L). This process is repeated 2-3 times. The coagulated polymer is air dried
for 24-
48 h and is then dried to constant weight at 50° C in a vacuum oven.
Any remaining
aluminum inorganic material is removed by exhaustively centrifuging a
tetrahydrofuran solution (0.1-0.15 g/mL) of the polymer, in which the aluminum
CA 02388946 2002-04-24
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inorganic material is insoluble. The polymer is decanted from the insoluble
material,
coagulated in fresh iSO-propyl alcohol, air dried for 24-48 h, and then dried
to constant
weight at 50° C in a vacuum oven. This process is repeated from 2-3
timPC Anv
homopolystyrene present in the polymer is removed by coagulating a
tetrahydrofuran
solution (0.1-0.15 g/mL) of the polymer in acetone (about 1.5-2 L). The
coagulated
polymer is then collected by decantation, air dried for 24-48 h, and then
dried to
constant weight at 50°C in a vacuum oven. This process can also be
repeated if
necessary. If the polymer contains polystyrene homopolymer, the polymer may,
if
desired, be dissolved in hexane and coagulated in acetone, effectively
removing
polystyrene. The interpolymer is free from impurities if a homogeneous
solution is
formed when a 10 wt% solution of the polymer is made with mineral oil.
Table 1
Heptane Reaction
(mL) fromEthyleneTemp.
ExampleHexane Styrene a-olefin MAO i ~~ Time
(~) (a) hl
s
1 489.2 454.5 oct, 163.2212 5~ 60 0.583
2 339.1 318.2 oct, 228.8212 55 60 0.5
3 496.1 374.8 hex, 201.9212 54.5 40 2
4 496.1 374.8 hex, 201.9212 35.6 20 3
5 496.1 374.8 hex, 201.9212 45 30 2
6 496.1 374.8 hex, 201.9212 54.5 40
7 496.1 374.8 hex, 201.9212 58 50 2
8 496.1 374.8 hex, 201.9212 73 60 2
9 496.1 374.8 hex, 201.9212 86 70 0.~
(g) - b ~s
(h) - hours
(mL) - milliliters
(psig) - pound per square inch, gauge
(hex) - hexene
(oct) - octene
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Table 2
Feed (mole Feed Ratio
%)
Example St a-olefinEth Styrene-ethylenea~lefin-ethylene
g ene I~
,
1 68.2 22.7 9.1 7.5 2.5
2 52.7 35.2 12.1 4.4 2.9
3 51.8 34.6 13.6 3.8 2.5
4 51.8 34.6 13.6 3.8 2.5
51.8 34.6 13.6 3.8 2,5
6 51.8 34.6 13.6 3.8 2.5
7 51.8 34.6 13.6 3.8 2.5
8 51.8 34.6 13.6 3.8 2.5
9 51.8 ~ 34.6 13.6 3.8 2.5
~
Results:
Results are tabulated in Tables 3-4.
Table 3
Example Conversion Yield a Al/Ti Activity
%
1 83 562.3 2,235 5853
2 86 510 ~,~35 6190
3 27 178 12,275 2967
4 9 57.1 12,275 ~ 634
5 13 84 12,275 1400
6 27 176.5 12,275 2942
7 61 350.5 12,275 5800
8 66 382.9 12,275 6300
9 69 397.3 12,275 26,200
* (Kb/mole Ti/h)
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Compositions of the copolymers of Examples 1-9 (mole %, measured by
1H NMR) and molecular weights, (GPC, (multiangle light scattering and
refractive
index for detection)) are set forth in Table 4:
Table 4
Example Styrene a-olefinEthylene dn/dc # (mlJg)M W M W/ M
n
1 27 15 58 0.137 74,340 1.63
2 23 25 53 0.137 75,230 2.59
3 27 37 36 0.137 206,800 1:48
4 27 47 26 0.137 465,200 1.4
27 39 34 0.137 306,300 1.69
6 31 51 18 0.137 196,400 1.6~
7 23 30 47 0.137 155.000 1.73
8 2~ 3~ 40 0.137 129,000 1.9
9 28 41 31 0.137 80,000 1.81
5 # differential refractive index
Other Additives
Additive concentrates and lubricating oil compositions of this invention may
contain other additives. The use of such additives is optional and the
presence thereof
in the compositions of this invention will depend on the particular use and
level of
performance required. Thus the other additive may be included or excluded.
Additive
concentrates of this invention typically comprise from about 0.1 % to about
30% by
weight of interpolvmer and from about 70% to about 99.9% by weight of a
substantially, inert, normally liquid, organic diluent.
Lubricating oil compositions often comprise zinc salts of a dithiophosphoric
acid, often referred to as zinc dithiophosphates, zinc O,O-dihydrocarbyl
dithiophosphates, and other commonly used names. They are sometimes referred
to
by the abbreviation ZDP. One or more zinc salts of dithiophosphoric acids may
be
present in a minor amount to provide additional extreme pressure, anti-wear
and anti-
oxidancy performance.
Other additives that may optionally be used in the lubricating oils of this
invention include, for example, detergents, dispersants, supplemental
viscosity
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improvers, oxidation inhibiting agents, corrosion inhibiting agents, pour
point
depressing agents, extreme pressure agents, anti-wear agents, color
stabilizers, friction
modifiers, and anti-foam agents.
Extreme pressure agents and corrosion and oxidation inhibiting agents which
may be included in the compositions of the invention are exemplified by
chlorinated
aliphatic hydrocarbons, organic sulfides and polysulfides, phosphorus esters
including
dihydrocarbon and trihydrocarbon phosphites, molybdenum compounds, and the
like.
Other oxidation inhibiting agents include materials such as alkylated diphenyl
amines, hindered phenols, especially those having tertiary alkyl groups such
as
tertiary butyl groups in the position ortho to the phenolic -OH group, and
others.
Such materials are well known to those of skill in the art.
Auxiliary viscosity improvers (also sometimes referred to as viscosity index
improvers or viscosity modifiers) may be included in the compositions of this
invention. Viscosity improvers are usually polymers, including polyisobutenes,
polymethacrylic acid esters, hydrogenated dime polymers, polyalkyl styrenes,
esterified styrene-malefic anhydride copolymers, hydrogenated alkenylarene-
conjugated dime copolymers and polyolefins. Multifunctional viscosity
improvers,
which also have dispersant and/or antioxidancy properties are known and may
optionally be used in addition to the products of this invention. Such
products are
described in numerous publications including those mentioned in the Background
of
the Invention. Each of these publications is hereby expressly incorporated by
reference.
Pour point depressants may be included in the additive concentrates and
lubricating oils described herein. Those which may be used are described in
the
literature and are well-known to those skilled in the art; see for example,
page 8 of
"Lubricant Additives" by C.V. Smalheer and R. Kennedy Smith (Lezius-Hiles
Company Publisher, Cleveland, Ohio, 1967). Pour point depressants useful for
the
purpose of this invention, techniques for their preparation and their use are
described
in U. S. Patent Nos. 2,387.501; 2,015,748; 2,655,479; 1,815,022; 2,191,498;
2,666,748; 2,721,877; 2,721,878; 3,250,715; and 5,707,943 which are expressly
incorporated herein by reference for their relevant disclosures.
14
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Anti-foam agents used to reduce or prevent the formation of stable foam
include silicones or organic polymers. Examples of these and additional anti-
foam
compositions are described in "Foam Control Agents", by Henry T. Kerner (Noyes
Data Corporation, 1976), pages 125-162.
Detergents and dispersants may be of the ash-producing or ashless type. The
ash-producing detergents are exemplified by oil soluble neutral and basic
salts of
alkali or alkaline earth metals with sulfonic acids, carboxylic acids, phenols
or organic
phosphorus acids characterized by a least one direct carbon-to-phosphorus
linkage.
The term "basic salt" is used to designate metal salts wherein the metal is
present in stoichiometrically larger amounts than the organic acid radical.
The
relative amount of metal present in "basic salts" is frequently indicated by
the
expression "metal ratio" (abbreviated MR), which is defined as the number of
equivalents of metal present compared to a "normal", stoichiometric amount.
Thus,
for example, a basic salt containing twice the amount of metal compared to the
stoichiometric amount, has a metal ratio (MR) of ?. Basic salts and techniques
for
preparing and using them are well known to those skilled in the art and need
not be
discussed in detail here.
Ashless detergents and dispersants are so-called despite the fact that,
depending on its constitution, the detergent or dispersant may upon combustion
yield
a nonvolatile residue such as boric oxide or phosphorus pentoxide; however, it
does
not ordinarily contain metal and therefore does not yield a metal-containing
ash on
combustion. Many types are known in the art, and any of them are suitable for
use in
the lubricants of this invention. The following are illustrative:
(1) Reaction products of carboxylic acids (or derivatives thereof) containing
at least about 34 and preferably at least about 54 carbon atoms with nitrogen
containing compounds such as amine, organic hydroxy compounds such as phenols
and alcohols, and/or basic inorganic materials. Examples of these "carboxylic
dispersants" are described in British Patent number 1,306,529 and in many U.S.
patents including the following:
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WO 01/30947 PCT/US00/29395
3,163,603 3,399,141 3,574,101
3,184,474 3,415,750 3,576,743
3,215,707 3,433,744 3,630,904
3,219,666 3,444,170 3,632,510
3,271,310 3,448,048 3,632,511
3,272,746 3,448,049 3,697,428
3,281,357 3,451,933 3,725,441
3,306,908 3,454,607 4,194,886
3,311,558 3,467,668 4,234,435
3,316,177 3,501,405 4,491,527
3,340,281 3,522,179 5,696,060
3 ,341,542 3,541,012 5,696,067
3,346,493 3,541,678 5,779,742
3,351,552 3,542,680 RE 26,433
3,381,022 3,567,637
(2) Reaction products of relatively high molecular weight aliphatic or
alicyclic halides with amines, preferably polyalkylene polyamines. These may
be
characterized as "amine dispersants" and examples thereof are described for
example,
in the following U.S. patents:
3,275,554 3,454,555
3,438,757 3,565.804
(3) Reaction products of alkyl phenols in which the alkyl groups contains at
least about 30 carbon atoms with aldehydes (especially formaldehyde) and
amines
(especially polyalkylene polyamines), which may be characterized as "Mannich
dispersants". The materials described in the following U. S. patents are
illustrative:'
3,413,347 3,725,480
3,697,574 3,726,882
3,725,277
(4) Products obtained by post-treating the carboxylic amine or Mannich
dispersants with such reagents as urea, thiourea, carbon disulfide, aldehydes,
ketones,
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WO 01/30947 PCT/US00/29395
carboxylic acids, hydrocarbon-substituted succinic anhydrides, nitrites,
epoxides,
boron compounds, phosphorus compounds or the like. Exemplary materials of this
kind are described in the following U.S. patents:
3,036,003 3,282,955 3,493,520 3,639,242
3,087,936 3,312,619 3,502,677 3,649,229
3,200,107 3,366,569 3,513,093 3,649,659
3,216,936 3,367,943 3,533,945 3,658,836
3,254,025 3,373,111 3,539,633 3,697,574
3,256,185 3,403,102 3,573,010 3,702,757
3,278,550 3,442,808 3,579,450 3,703,536
3,280,234 3,455,831 3,591,598 3,704,308
3,281,428 3,455,832 3,600,372 3,708,522
4,234,435
(5) Polymers and copolymers of oil-solubilizing monomers such as decyl
methacrylate, vinyl decyl ether and high molecular weight olefins with
monomers
containing polar substituents, e.g., aminoalkyl acrylates or methacrylates,
acrylamides
and poly-(oxyethylene)-substituted acrylates. These may be characterized as
"polymeric dispersants" and examples thereof are disclosed in the following
U.S.
patents:
3,329,658 3,666,730
3,449,250 3,687,849
3,519,565 3,702,300
The above-noted patents are incorporated herein by reference for their
disclosures of
ashless dispersants.
The above-illustrated other additives may each be present in lubricating
compositions at a concentration of as little as 0.001% by weight, usually
ranging from
about 0.01% to about 20% by weight. In most instances, they each contribute
from
about 0.1% to about 10% by weight, more often up to about 5% by weight.
Additive Concentrates
The various additive compositions of this invention described herein can be
added directly to the oil of lubricating viscosity. Preferably, however, they
are diluted
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CA 02388946 2002-04-24
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with a substantially inert, normally liquid organic diluent such as mineral
oil, a
synthetic oil such as a polyalphaolefin, naphtha, benzene, toluene or xylene,
to form
an additive concentrate. These concentrates usually comprise about 0.1 to
about 30%
by weight, frequently from about 1% to about 20% by weight, more often from
about
5% to about 15% by weight, of the interpolymers of this invention and may
contain,
in addition, one or more other additives known in the art or described
hereinabove.
Additive concentrates are prepared by mixing together the desired
components, often at elevated temperatures, usually less than 150° C,
often no more
than about 130° C , frequently no more than about 115° C.
Lubricating Oil Compositions
The interpolymers of this invention are useful as viscosity improving agents.
They are used in viscosity improving amounts, typically minor amounts, that is
less
than 50% by weight of the lubricating oil composition with a major amount of
an oil
of lubricating viscosity, that is, the oil of lubricating viscosity comprises
greater than
50% by weight of the lubricating oil composition. Preferably, they are used in
amounts ranging from about 0.1 to about 5% by weight, more often from about
0.3 to
about 2.5% by weight of the total weight of the lubricating oil composition.
The Oil of Lubricating Viscosi~
The lubricating compositions of this invention employ an oil of lubricating
viscosity, including natural or synthetic lubricating oils and mixtures
thereof. Mixture of
mineral oil and synthetic oils, particularly polyalphaolefin oils and
polyester oils, are
often used.
Natural oils include animal oils and vegetable oils (e.g. castor oil, lard oil
and
other vegetable acid esters) as well as mineral lubricating oils such as
liquid petroleum
oils and solvent-treated or acid treated mineral lubricating oils of the
para~nic,
naphthenic or mixed paraffinic-naphthenic types. Hydrotreated or hydrocracked
oils are
included within the scope of useful oils of lubricating viscosity.
Oils of lubricating viscosity derived from coal or shale are also useful.
Synthetic
lubricating oils include hydrocarbon oils and halosubstituted hydrocarbon oils
such as
polymerized and interpolymerized olefins, etc. and mixtures thereof,
alkylbenzenes,
polyphenyl, (e.g., biphenyls, terphenyls, alkylated polyphenyls, etc.),
alkylated diphenyl
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WO 01/30947 PCT/US00/29395
ethers and alkylated diphenyl sulfides and their derivatives, analogs and
homologues
thereof and the like.
Alkylene oxide polymers and interpolymers and derivatives thereof, and those
where terminal hydroxyl groups have been modified by esterification,
etherification, etc.,
constitute other classes of known synthetic lubricating oils that can be used.
Another suitable class of synthetic lubricating oils that can be used
comprises the
esters of dicarboxylic acids and those made from CS to C1z monocarboxylic
acids and
polyols or polyether polyols.
Other synthetic lubricating oils include liquid esters of phosphorus-
containing
acids, polymeric tetrahydrofurans, alkylated diphenyloxides and the like.
Unrefined, refined and rerefined oils, either natural or synthetic (as well as
mixtures of two or more of any of these) of the type disclosed hereinabove can
used in
the compositions of the present invention. Unrefined oils are those obtained
directly
from a natural or synthetic source without further purification treatment.
Refined oils are
similar to the unrefined oils except they have been further treated in one or
more
purification steps to improve one or more properties. Rerefined oils are
obtained by
processes similar to those used to obtain refined oils applied to refined oils
which have
been already used in service. Such rerefined oils often are additionally
processed by
techniques directed to removal of spent additives and oil breakdown products.
Specific examples of the above-described oils of lubricating viscosity are
given
in Chamberlin III, LT.S. 4,326,972 and European Patent Publication 107,282,
both of
which are hereby incorporated herein by reference for relevant disclosures
contained
therein.
A basic, brief description of lubricant base oils appears in an article by
D.V.
Brock, "Lubrication Engineering", Volume 43, pages 184-5, March, 1987, which
article is expressly incorporated by reference for relevant disclosures
contained
therein.
The following examples illustrate lubricating oil compositions of this
invention. All parts are parts by weight. Amounts are on an oil or diluent
free basis,
except for products of Examples set forth herein which are as prepared,
including
diluent, if any.
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WO 01/30947 PCT/US00/29395
Examples A-B
A master additive concentrate is prepared by combining 1.34 parts calcium
overbased (MR 20) alkyl benzene sulfonic acid, 0.62 parts calcium overbased
(MR
2.8) alkyl benzene sulfonic acid, 1.54 parts magnesium overbased (MR 14.7)
alkyl
benzene sulfonic acid, 16.60 parts polyisobutylene ( M n - 1750) substituted
succinic
anhydride-ethylene polyamine bottoms reaction product, 7.61 parts of Zn mixed
isopropyl-methyl amyl phosphorodithioate, 2.78 parts calcium overbased (MR
3.5)
sulfurized alkyl phenol, 3.19 parts sulfurized butadiene-butyl acrylate Diels-
Alder
adduct, 0.08 parts of a kerosene solution of a commercial silicone antifoam, 1
part of
sodium overbased (MR 16) polyisobutylene ( M n ~ 1000) substituted succinic
acid,
6.85 parts polyisobutylene ( M n - 1000) substituted succinic anhydride-
pentaerythritol-ethylene polyamine reaction product, 4.84 parts alkylated
diphenyl
amine and sufficient mineral oil to bring the total weight of the additive
concentrate to
100 parts.
Engine oil compositions are prepared by combining 11 parts of the master
concentrate, 0.02 parts by weight of a hydrogenated styrene butadiene
copolymer and
the indicated amount of the product of the indicated Example in sufficient
mineral oil
basestock (Petro-Canada SAE SW-30) to prepare 100 parts by weight of oil
composition. Details regarding each are provided in the following table:
Example A B C D E F
Product of Example/(pbw):1/1.853/1.00 4/0.757/1.32 8/1.46 9/1.64
Viscosity Index (D-2270)175 167 168 155 153 150
I I
Shear Characteristics:10.31 8.65 8.24 9.025 9.31 9.74
30 Pass Orbahn (D-6278)
cSt
@ 100 C
SSI (D-6022) 17.8 49.5 67.2 38.0 30.9 20.6
Cold Cranking Vis, 3,850 2,920 3,620 3,810 3,950 4,190
cP @-25C
(D-5293)
HTHS Vis, cP @150C 3.44 3.11 3.29 3.21 3.20 3.24
(D-4683)
MRV Vis cP @-35C 35,90019,800 33,90028,100 34,200 29,200
(D04684)
(pbw)
-
parts
by
weight
CA 02388946 2002-04-24
WO 01/30947 PCT/US00/29395
It is known that some of the materials described above may interact in the
final
formulation, so that the components of the final formulation rnay be different
from
those that are initially added. For instance, metal ions (of, e.g., a
detergent) can
migrate to other acidic sites of other molecules. The products formed thereby,
including the products formed upon employing the composition of the present
invention in its intended use, may not susceptible of easy description.
Nevertheless,
all such modifications and reaction products are included within the scope of
the
present invention; the present invention encompasses the composition prepared
by
admixing the components described above.
Each of the documents referred to above is incorporated herein by reference.
Except in the examples, or where otherwise explicitly indicated, all numerical
quantities in this description specifying amounts of materials, reaction
conditions,
molecular weights, number of carbon atoms, and the like, are to be understood
as
modified by the word "about". Unless otherwise indicated, each chemical or
composition referred to herein should be interpreted as being a commercial
grade
material which may contain the isomers, by-products, derivatives, and other
such
materials which are normally understood to be present in the commercial grade.
However, the amount of each chemical component is presented exclusive of any
solvent or diluent oil which may be customarily present in the commercial
material,
unless otherwise indicated. It is to be understood that the upper and lower
amount,
range, and ratio limits set forth herein may be independently combined. As
used
herein, the expression "consisting essentially of" permits the inclusion of
substances
which do not materially affect the basic and novel characteristics of the
composition
under consideration.
While the invention has been explained in relation to its preferred
embodiments, it is to be understood that various modifications thereof will
become
apparent to those skilled in the art upon reading the specification.
Therefore, it is to
be understood that the invention disclosed herein is intended to cover such
modifications that fall within the scope of the appended claims.
21
