U.S. patent application number 13/636205 was filed with the patent office on 2013-01-10 for lubricant component.
This patent application is currently assigned to E I Dupont De Nemours and Company. Invention is credited to Joel David Citron.
Application Number | 20130012659 13/636205 |
Document ID | / |
Family ID | 44067287 |
Filed Date | 2013-01-10 |
United States Patent
Application |
20130012659 |
Kind Code |
A1 |
Citron; Joel David |
January 10, 2013 |
LUBRICANT COMPONENT
Abstract
A lubricant component is a copolymer of ethylene and
.alpha.-olefins made by forming a series of .alpha.-olefins by
oligomerization of ethylene using an oligomerization catalyst, and
then copolymerizing the .alpha.-olefins and ethylene using a
transition metalcontaining polymerization catalyst. The copolymer,
which often has a high Viscosity Index, may be used, for example,
in a lubricant as the base oil or a viscosity index modifier. The
polyolefin may also be a component of a lubricant additive, meant
to be added to an already formulated lubricant to improve the
lubricant's properties.
Inventors: |
Citron; Joel David;
(Wilmington, DE) |
Assignee: |
E I Dupont De Nemours and
Company
Wilmington
DE
|
Family ID: |
44067287 |
Appl. No.: |
13/636205 |
Filed: |
March 28, 2011 |
PCT Filed: |
March 28, 2011 |
PCT NO: |
PCT/US11/30128 |
371 Date: |
September 20, 2012 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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61318570 |
Mar 29, 2010 |
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61318556 |
Mar 29, 2010 |
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61357368 |
Jun 22, 2010 |
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61357362 |
Jun 22, 2010 |
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61362563 |
Jul 8, 2010 |
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61390365 |
Oct 6, 2010 |
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Current U.S.
Class: |
525/55 ;
526/90 |
Current CPC
Class: |
C08F 110/02 20130101;
C08F 4/70 20130101; C08F 4/7042 20130101; C08F 110/02 20130101;
C08F 2500/09 20130101; C08F 4/61904 20130101; C08F 110/02 20130101;
C08F 2500/02 20130101; C08F 4/7042 20130101; C08F 110/02
20130101 |
Class at
Publication: |
525/55 ;
526/90 |
International
Class: |
C08F 210/14 20060101
C08F210/14; C08F 210/08 20060101 C08F210/08 |
Claims
1-14. (canceled)
15. A lubricant or a lubricant additive, comprising a polyolefin
made by a process comprising: (1) contacting, under oligomerizing
and polymerizing conditions, (a) an oligomerization catalyst that
oligomerizes ethylene to a series of .dbd.-olefins having the
formula H(CH.sub.2CH.sub.2).sub.nCH.dbd.CH.sub.2 wherein n is an
integer of one or more, and said oligomerization catalyst has a
Schulz-Flory constant of about 0.40 to about 0.95; (b) a transition
metal-containing copolymerization catalyst that copolymerizes
ethylene and said .alpha.-olefins; and (c) ethylene; or (2) (a)
contacting, under oligomerizing conditions, ethylene and an
oligomerization catalyst that oligomerizes ethylene to a series of
.alpha.-olefins having the formula
H(CH.sub.2CH.sub.2).sub.nCH.dbd.CH.sub.2, wherein n is an integer
of one or more, and said oligomerization catalyst has a
Schulz-Flory constant of about 0.40 to about 0.85; and then (b)
contacting under polymerizing conditions said series of
.alpha.-olefins, ethylene, and said transition metal containing
copolymerization catalyst which copolymerizes ethylene and said
.alpha.-olefins; and then (3) optionally modifying said polyolefin
to improve its properties for use in said lubricant or lubricant
additive; and wherein said polyolefin has a density of about 0.90
or less, and said polyolefin is a random copolymer.
16. The lubricant or lubricant additive of claim 15 wherein said
ethylene, said oligomerization catalyst, and said copolymerization
catalyst are contacted together.
17. The lubricant or lubricant additive as recited in claim 15
wherein said oligomerization catalyst has a Schulz-Flory constant
of about 0.55 to about 0.85.
18. The lubricant or lubricant additive as recited in claim 15
wherein polymerizing with said copolymerization catalyst is carried
out in solution.
19. The lubricant or lubricant additive as recited in claim 15
wherein said oligomerization catalyst is an iron complex of a
ligand of the formula: ##STR00002## wherein: R.sup.1, R.sup.2, and
R.sup.3 are each independently hydrogen, hydrocarbyl, substituted
hydrocarbyl, or an inert functional group, provided that any two of
R.sup.1, R.sup.2, and R.sup.3 vicinal to one another, taken
together may form a ring; R.sup.4 and R.sup.5 are each
independently hydrogen, hydrocarbyl, substituted hydrocarbyl, or an
inert functional group, provided that R.sup.1 and R.sup.4 and/or
R.sup.3 and R.sup.5 taken together may form a ring; and R.sup.6 and
R.sup.7 are each independently aryl or substituted aryl.
20. The lubricant or lubricant additive as recited in claim 19
wherein said oligomerization catalyst has a Schulz-Flory constant
of about 0.55 to about 0.85.
21. The lubricant or lubricant additive as recited in claim 15
wherein said polyolefin has a density of about 0.88 or less.
22. The lubricant or lubricant additive as recited in claim 19
wherein said polyolefin has a density of about 0.88 or less.
23. The lubricant or lubricant additive as recited in claim 15
wherein a mole percent branching level of said polyolefin is about
5.0 to about 40.0.
24. The lubricant or lubricant additive as recited in claim 19
wherein a mole percent branching level of said polyolefin is about
5.0 to about 40.0.
25. The lubricant or lubricant additive as recited in claim 15
wherein said polyolefin has a number average molecular weight of
about 500 to about 20,000.
26. The lubricant or lubricant additive as recited in claim 19
wherein said polyolefin has a number average molecular weight of
about 500 to about 20,000.
27. The lubricant or lubricant additive as recited in claim 15
wherein said polyolefin is hydrogenated.
28. The lubricant or lubricant additive as recited in claim 19
wherein said polyolefin is hydrogenated.
29. The lubricant or lubricant additive as recited in claim 15
wherein said polyolefin is a base oil.
30. The lubricant or lubricant additive as recited in claim 19
wherein said polyolefin is a base oil.
31. The lubricant or lubricant additive as recited in claim 15
wherein said polyolefin is a viscosity index modifier.
32. The lubricant or lubricant additive as recited in claim 19
wherein said polyolefin is a viscosity index modifier.
33. The lubricant or lubricant additive as recited in claim 15
wherein said polyolefin has a viscosity index of about 125 or
more.
34. The lubricant or lubricant additive as recited in claim 19
wherein said polyolefin has a viscosity index of about 125 or more.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] This application claims the benefit of priority of U.S.
Provisional Application Nos. 61/318,556 filed on Mar. 29, 2010;
61/318,570 filed on Mar. 29, 2010; 61/362,563 filed on Jul. 8,
2010; 61/357,362 filed on Jun. 22, 2010 and 61/357,368 filed on
Jun. 22, 2010 which are herein incorporated by reference in their
entirety.
FIELD OF THE INVENTION
[0002] A lubricant or lubricant additive that contains a polyolefin
that is made by contacting an ethylene oligomerization catalyst
with ethylene to form a series of .alpha.-olefins, and then
copolymerizing those .alpha.-olefins with ethylene using a
polymerization catalyst that contains a complex of a transition
metal to form the polyolefin.
BACKGROUND OF THE INVENTION
[0003] Lubricants are most commonly used to reduce friction between
two moving parts in "contact" with each other, reducing wear of
those parts, reducing corrosion of parts particularly metal parts,
damping shock particularly in gears and forming seals as in between
piston rings and engine cylinders. Probably the most common type of
lubricant is used for machinery where metal, plastic, ceramic, etc.
parts that rub against each other may be present in items such as
internal combustion engines, transmissions, bearing assemblies,
etc., but lubricants have other uses, for example in cosmetics.
[0004] Many lubricant compositions have a variety of ingredients in
them, for instance heat stabilizers to prevent thermal degradation,
antioxidants, viscosity index improvers, detergents, dispersants,
pour point depressants, friction modifiers, demulsifiers, corrosion
inhibitors, etc. Many of these additives and other ingredients are
described in Morteier et al., Chemistry and Technology of
Lubricants", 2.sup.nd. Ed., London, Springer (1996) and Leslie R.
Rudnick, Lubricant additives": Chemistry and Applications," New
York, Marcel Dekker (2003), both of which are hereby included by
reference. For lubricants that have to be useful over wide
temperature ranges, such as internal combustion or jet engines, or
are exposed to a wide range of ambient temperatures, it is
important that the viscosity of the lubricant change little with
temperature. This is often referred to as the "Viscosity Index,"
("VI") and a higher number indicates less change in the viscosity
as the temperature rises (this is usually good).
[0005] Two of the major polymeric ingredients that may have high
Viscosity Indices ("VIs") are typically "base oils," which are
often the ingredient present in the largest amount, and "viscosity
index improvers." These polymeric materials are generally
classified into groups, and one group of such polymers is Group IV,
polyalphaolefins (PAOs), which typically have high VIs. These are
polymers or copolymers of one or more .alpha.-olefins of the
formula H.sub.3C(CH.sub.2).sub.yCH.dbd.CH.sub.2 wherein y is about
5 to about 27. In some instance the alkyl groups in the
.alpha.-olefin may be branched.
[0006] U.S. Pat. Nos. 7,662,881 and 7,687,443 describe lubricants
or lubricant components that include an ethylene copolymer with one
or more .alpha.-olefins. These copolymers are said to be block
copolymers and not random copolymers.
[0007] U.S. Patent Publication 2003/0195128 describes a lubricant
additive that is an "olefin oligomer." This olefin oligomer, "PAO
fluid," is made by polymerization of an .alpha.-olefin using
"Friedel-Crafts catalyst" such as aluminum trichloride or boron
trifluoride. Ethylene-alpha-olefin copolymers are also
mentioned.
[0008] U.S. Pat. No. 6,568,723 describes the use of certain
metallocene catalysts to make polyolefins from C.sub.3 to C.sub.20
olefins which may be meant to be used in lubricants. The use of
ethylene as a comonomer is not mentioned.
SUMMARY OF THE INVENTION
[0009] This invention concerns a lubricant or a lubricant additive,
comprising a polyolefin made by a process comprising:
[0010] (1) contacting under oligomerizing and polymerizing
conditions
[0011] (a) an oligomerization catalyst that oligomerizes ethylene
to a series of .alpha.-olefins having the formula
H(CH.sub.2CH.sub.2).sub.nCH.dbd.CH.sub.2 wherein n is an integer of
one or more and said oligomerization catalyst has a Schulz-Flory
constant of about 0.40 to about 0.95;
[0012] (b) a transition metal containing copolymerization catalyst
that copolymerizes ethylene and said .alpha.-olefins; and
[0013] (c) ethylene;
or
[0014] (2) (a) contacting under oligomerizing conditions ethylene
and said oligomerization catalyst that oligomerizes ethylene to a
series of .alpha.-olefins having the formula
H(CH.sub.2CH.sub.2).sub.nCH.dbd.CH.sub.2 wherein n is an integer of
one or more and said oligomerization catalyst has a Schulz-Flory
constant of about 0.40 to about 0.95; and then
[0015] (b) contacting under polymerizing conditions said series of
.alpha.-olefins, ethylene, and said transition metal containing
copolymerization catalyst which copolymerizes ethylene and said
.alpha.-olefins; and then
[0016] (3) optionally modifying said polyolefin to improve its
properties for use in said lubricant or lubricant additive;
[0017] and wherein said polyolefin has a density of about 0.90 or
less, and said polyolefin is a random copolymer.
[0018] It is to be noted that either step (1) (a-c) or step (2)
(a-b) is carried out, optionally followed by step (3). Other
features and advantages of the present invention will be better
understood by reference to the detailed description that
follows.
DETAILED DESCRIPTION OF THE INVENTION
[0019] Herein certain terms are used and some of these are defined
below:
[0020] By a "transition metal-containing copolymerization catalyst"
is meant a catalyst that contains a transition metal of Groups 3-12
(IUPAC notation) and the lanthanides, such Zr, Hf, V, Ti, etc.
Typically these may be metallocene catalysts, Ziegler-Natta
catalysts, chromium catalysts, etc. These types of catalysts are
well known in the polyolefin field, see for instance Angew. Chem.,
Int. Ed. Engl., vol. 34, p. 1143-1170 (1995), EP-A-0416815 and U.S.
Pat. No. 5,198,401 for information about metallocene-type
catalysts; and J. Boor Jr., Ziegler-Natta Catalysts and
Polymerizations, Academic Press, New York, 1979 for information
about Ziegler-Natta type catalysts, all of which are hereby
included by reference. Chromium catalysts are also well known, see
for instance E. Benham, et al., Ethylene Polymers, HDPE in
Encyclopedia of Polymer Science and Technology (online), John Wiley
& Sons, and D. M. 5 Simpson, et al., Ethylene Polymers, LLDPE,
in Encyclopedia of Polymer Science and Technology (online), John
Wiley & Sons, both of which are hereby included by
reference.
[0021] By a "random copolymer" is meant that there is random
sequencing of the copolymer repeat units in the polyolefin, see J.
C. Randall, Encyclopedia of Polymer Science and Technology,
(online), John Wiley & Sons, DOI 10.1002/0471440264.pst557
(2008), which is hereby included by reference.
[0022] By an ".alpha.-olefin" is meant a compound of the formula
H(CH.sub.2CH.sub.2).sub.nCH.dbd.CH.sub.2 wherein n is an integer of
1 or more.
[0023] By a "series" of .alpha.-olefins is meant compounds having
the formula H(CH.sub.2CH.sub.2).sub.nCH.dbd.CH.sub.2 wherein at
least three, preferably 4, and more preferably 5, compounds having
different n values are produced, and n is an integer of 1 or more.
Preferably at least three of these values are 1, 2, and 3.
[0024] By "hydrocarbyl group" is meant a univalent group containing
only carbon and hydrogen. As examples of hydrocarbyls may be
mentioned unsubstituted alkyls, cycloalkyls and aryls. If not
otherwise stated, it is preferred that hydrocarbyl groups (and
alkyl groups) herein contain from 1 to about 30 carbon atoms.
[0025] By "substituted hydrocarbyl" herein is meant a hydrocarbyl
group that contains one or more substituent groups that are inert
under the process conditions to which the compound containing these
groups is subjected (e.g., an inert functional group, see below).
The substituent groups also do not substantially detrimentally
interfere with the polymerization process or the operation of the
polymerization catalyst system. If not otherwise stated, it is
preferred that (substituted) hydrocarbyl groups herein contain from
1 to about 30 carbon atoms. Included in the meaning of
"substituted" are rings containing one or more heteroatoms, such as
nitrogen, oxygen and/or sulfur, and the free valence of the
substituted hydrocarbyl may be to the heteroatom. In a substituted
hydrocarbyl, all of the hydrogens may be substituted, as in
trifluoromethyl.
[0026] By an "(inert) functional group" herein is meant a group,
other than hydrocarbyl or substituted hydrocarbyl, that is inert
under the process conditions to which the compound containing the
group is subjected. The functional groups also do not substantially
deleteriously interfere with any process described herein that the
compound in which they are present may take part in. Examples of
functional groups include halo (fluoro, chloro, bromo, and iodo),
and ether such as --OR.sup.50 wherein R.sup.50 is hydrocarbyl or
substituted hydrocarbyl. In cases in which the functional group may
be near a transition metal atom, the functional group alone should
not coordinate to the metal atom more strongly than the groups in
those compounds that are shown as coordinating to the metal atom,
that is, they should not displace the desired coordinating
group.
[0027] By a "cocatalyst" or a "catalyst activator" is meant one or
more compounds that react with a transition metal compound to form
an activated catalyst species. One such catalyst activator is an
"alkylaluminum compound," which herein means a compound in which at
least one alkyl group is bound to an aluminum atom. Other groups
such as, for example, alkoxide, hydride, an oxygen atom bridging
two aluminum atoms, and halogen may also be bound to aluminum atoms
in the compound.
[0028] The "Schulz-Flory constant" ("SFC") of the mixtures of
.alpha.-olefins produced is a measure of the molecular weights of
the olefins obtained, usually denoted as factor K, from the
Schulz-Flory theory (see for instance B. Elvers, et al., Ed.
Ullmann's Encyclopedia of Industrial Chemistry, Vol. A13, VCH
Verlagsgesellschaft mbH, Weinheim, 1989, p. 243-247 and 275-276).
This is defined as:
K=n(C.sub.n+2olefin)/n(C.sub.n olefin)
wherein n(C.sub.n olefin) is the number of moles of olefin
containing n carbon atoms, and n(C.sub.n+2 olefin) is the number of
moles of olefin containing n+2 carbon atoms, or in other words the
next higher oligomer of C.sub.n olefin. From this can be determined
the weight (mass) and/or mole fractions of the various olefins in
the resulting oligomeric reaction product mixture.
[0029] By a "copolymerization catalyst" is meant a catalyst that
can readily, under the process conditions, copolymerize ethylene
and .alpha.-olefins of the formula
H(CH.sub.2CH.sub.2).sub.nCH.dbd.CH.sub.2 wherein n is an integer of
one or more.
[0030] By "aryl" is meant a monovalent aromatic group in which the
free valence is to the carbon atom of an aromatic ring. An aryl may
have one or more aromatic rings, which may be fused, connected by
single bonds or other groups.
[0031] By "substituted aryl" is meant a monovalent aromatic group
substituted that contains one or more substituent groups that are
inert under the process conditions to which the compound containing
these groups is subjected (e.g., an inert functional group, see
below). The substituent groups also do not substantially
detrimentally interfere with the polymerization process or
operation of the polymerization catalyst system. If not otherwise
stated, it is preferred that (substituted) aryl groups herein
contain from 1 to about 30 carbon atoms. Included in the meaning of
"substituted" are rings containing one or more heteroatoms, such as
nitrogen, oxygen and/or sulfur, and the free valence of the
substituted hydrocarbyl may be to the heteroatom. In a substituted
aryl all of the hydrogens may be substituted, as in
trifluoromethyl. These substituents include (inert) functional
groups. Similar to an aryl, a substituted aryl may have one or more
aromatic rings, which rings may be fused or connected by single
bonds or other groups; however, when the substituted aryl has a
heteroaromatic ring, the free valence in the substituted aryl group
can be to a heteroatom (such as nitrogen) of the heteroaromatic
ring instead of a carbon.
[0032] By "process conditions" herein is meant conditions for
producing the series of .alpha.-olefins, whether in the presence of
the copolymerization catalyst or not. Such conditions may include
temperature, pressure, and/or oligomerization method such as liquid
phase, continuous, batch, and the like. Also included may be
cocatalysts that are needed and/or desirable. If in the presence of
the copolymerization catalyst, the SFC is measured under conditions
in which the copolymerization catalyst is not present.
[0033] Many types of catalysts are useful as the copolymerization
catalyst. For instance, so-called Ziegler-Natta, metallocene-type
and/or chromium catalysts may be used. These types of catalysts are
well known in the polyolefin field, see for instance Angew. Chem.,
Int. Ed. Engl., vol. 34, p. 1143-1170 (1995), EP-A-0416815 and U.S.
Pat. No. 5,198,401 for information about metallocene-type
catalysts; and J. Boor Jr., Ziegler-Natta Catalysts and
Polymerizations, Academic Press, New York, 1979 for information
about Ziegler-Natta type catalysts, all of which are hereby
included by reference. Chromium catalysts are also well known, see
for instance E. Benham, et al., Ethylene Polymers, HDPE in
Encyclopedia of Polymer Science and Technology (online), John Wiley
& Sons, and D. M. 5 Simpson, et al., Ethylene Polymers, LLDPE,
in Encyclopedia of Polymer Science and Technology (online), John
Wiley & Sons, both of which are hereby included by reference.
Many of the useful polymerization conditions for these types of
catalysts and the oligomerization catalyst coincide, so conditions
for the process are easily accessible. Oftentimes a "cocatalyst" or
"activator" is needed for metallocene or Ziegler-Natta type
polymerizations, which cocatalyst is oftentimes the same as is
sometimes needed for the oligomerization catalyst. In many
instances cocatalysts or other compounds, such as an alkylaluminum
compound, may be used with both types of catalysts.
[0034] Suitable catalysts for the copolymerization catalyst also
include metallocene-type catalysts, as described in U.S. Pat. No.
5,324,800 and EP-A-0129368; particularly advantageous are bridged
bis-indenyl metallocenes, for instance as described in U.S. Pat.
No. 5,145,819 and EP-A-0485823. Another class of suitable catalysts
comprises the well known constrained geometry catalysts, as
described in EP-A-0416815, EP-A-0420436, EP-A-0671404, EP-A-0643066
W091104257. Also the class of transition metal complexes described
in, for example, W098130609, U.S. Pat. Nos. 5,880,241, 5,955,555,
6,060,569 and 5,714,556 can be used. All of the aforementioned
publications are incorporated by reference herein.
[0035] The catalyst for the copolymerization of the ethylene and
the .alpha.-olefin series should preferably be a catalyst that can
copolymerize ethylene and .alpha.-olefins so that the relative rate
of copolymerization of these two types of monomers are very roughly
equal. Metallocene-type catalysts are most preferred, and preferred
metallocene catalysts are those listed in previously incorporated
World Patent Application 1999/150318, which is hereby included by
reference. Other types of preferred metallocene catalysts, which
are said to be especially useful for larger olefins, are described
in U.S. Pat. Nos. 6,642,169 and 6,509,228, both of which are hereby
included by reference.
[0036] It is to be understood that "oliogomerization catalyst" and
"copolymerization catalyst" may also include other compounds such
as cocatalysts and/or other compounds normally used with the
oliogomerization catalyst and/or copolymerization catalyst to
render that particular catalyst active for the polymerization or
oligomerization it is meant to carry out.
[0037] A preferred oligomerization catalyst is an iron complex of a
ligand of the formula:
##STR00001##
[0038] wherein: R.sup.1, R.sup.2 and R.sup.3 are each independently
hydrogen, hydrocarbyl, substituted hydrocarbyl or an inert
functional group, provided that any two of R.sup.1, R.sup.2, and
R.sup.3 vicinal to one another, taken together may form a ring;
R.sup.4 and R.sup.5 are each independently hydrogen, hydrocarbyl,
substituted hydrocarbyl or an inert functional group, provided that
R.sup.1 and R.sup.4 and/or R.sup.3 and R.sup.5 taken together may
form a ring; and R.sup.6 and R.sup.7 are each independently aryl or
substituted aryl.
[0039] In an iron complex of (I), (I) is usually thought of as a
tridentate ligand coordinated to the iron atom through the two
imino nitrogen atoms and the nitrogen atom of pyridine ring. It is
generally thought that the more sterically crowded it is about the
iron atom the higher the molecular weight of the polymerized olefin
(ethylene). In order to make .alpha.-olefins, and especially to
make in a process the desired SFC (such as 0.40-0.95) very little
steric crowding about the iron atom is desired.
[0040] Such compounds of (I) are readily available. For instance in
WO2005/092821 it is demonstrated that the iron complex in which
R.sup.4 and R.sup.5 are both hydrogen, and R.sup.6 and R.sup.7 are
both phenyl, has a SFC of about 0.29 (this reference states the SFC
is about 0.4, but this apparently based incorrectly on the weight
fraction of the olefins produced, not correctly mole fraction). In
G. J. P. Britovsek et al., Chem. Eur. J., vol. 6 (No. 12), p.
2221-2231 (2000), which is hereby included by reference, a ligand
in which R.sup.4 and R.sup.5 are both hydrogen and R.sup.6 and
R.sup.7 are both 2-methylphenyl, gives an oligomerization at
50.degree. C. in which the SFC is reported to be 0.50. Other
combinations of groups would give ligands with useful relatively
low SFCs. For instance, R.sup.4 and R.sup.5 may both be methyl or
hydrogen (or one could be methyl and one could be hydrogen) and
R.sup.6 could be phenyl, while R.sup.7 could be 2-fluorophenyl or
2-methylphenyl or 2-chlorophenyl; or R.sup.6 and R.sup.7 could both
be 2-fluorophenyl; or R.sup.6 and R.sup.7 could both be
4-isopropylphenyl; or both R.sup.6 and R.sup.7 could both be
4-methylphenyl. Other variations in which just small increments of
steric hindrance are added or subtracted about the iron atom are
obvious to those skilled in the art. It is also believed that in
addition to these steric effects that electron withdrawing groups
on R.sup.6 and/or R.sup.7 tend to lower the SFC.
[0041] For "moderate" SFCs, those in the approximate range of about
0.55 to about 0.70 R.sup.4 and R.sup.5 may both be methyl and
R.sup.6 and R.sup.7 may both be 2-methylphenyl or 2-ethylphenyl, or
R.sup.4 and R.sup.5 may both be methyl and R.sup.6 may be
2,6-dimethylphneyl and R.sup.7 may phenyl. See for instance U.S.
Pat. Nos. 6,103,946, 7,049,442 and 7,053,020, all of which are
hereby included by reference.
[0042] For higher SFCs somewhat more sterically crowded complexes
can be used. R.sup.4 and R.sup.5 may both be methyl and R.sup.6 may
both be 2,6-dimethylphenyl and R.sup.7 may be 2-methylphenyl, or
R.sup.4 and R.sup.5 may both be methyl and R.sup.6 may be
2,6-diisopropyllphenyl and R.sup.7 may 2-isopropylphenyl.
[0043] The synthesis of the ligands (I) and their iron complexes
are well known, see for instance U.S. Pat. Nos. 6,103,946,
7,049,442 and 7,053,020, G. J. P. Britovsek, et al., cited above,
and World Patent Application WO2005/092821, World Patent
Applications 1999/012981 and 2000/050470, all of which are hereby
included by reference.
[0044] Other relatively small aryl groups may also be used, such as
1-pyrrolyl, made from substituted or unsubstituted 1-aminopyrrole
(see for instance World Patent Application 2006/0178490, which is
hereby included by reference). Analogous substitution patterns to
those carried out in phenyl rings may also be used to attain the
desired degree of steric hindrance, and hence the desired SFC. Aryl
groups containing 5-membered rings such as 1-pyrrolyl may
especially useful for obtaining low SFCs, since they are generally
less sterically crowding than 6-membered rings. Preferred aryl
groups for R.sup.6 and R.sup.7 are phenyl and substituted
phenyl.
[0045] While steric hindrance about the iron atom is usually the
dominant item controlling the SFC, process conditions may have a
lesser effect. Higher process temperatures generally give lower
SFCs, while higher ethylene pressures (concentrations) generally
give a higher SFC, all other conditions being equal. In order to
measure the SFC of the oligomerization during the manufacture of
the branched polyethylene the process is carried out using the same
conditions as the process to produce the branched polyethylene, but
the copolymerization catalyst is omitted and any cocatalysts are
scaled back in relationship to the total amount of oliogomerization
catalyst present compared to the total of the copolymerization
catalyst and oligomerization catalyst usually used. However it is
to be noted that somewhat more than normal cocatalyst, such as an
alkylaluminum compound, may have to be used to remove traces of any
process poisons present such as water.
[0046] To determine the SFC, the resulting mixture of
.alpha.-olefins is analyzed to determine their molecular ratios.
This is most conveniently done by standard gas chromatography using
appropriate standards for calibration. Preferably the ratios (as
defined by the equation for "K," above) between olefins from
C.sub.4 to C.sub.12 are each measured and then averaged to obtain
the SFC. If the ratios of higher olefins, such as C.sub.12/C.sub.10
are too small to measure accurately, they may be omitted from the
calculation of the constant.
[0047] Under a given set of process conditions, generally the
higher the molar ratio of oligomerization catalyst to
copolymerization catalyst, the higher the branching level in the
branched polyethylene produced. This is true because the higher the
relative concentration of oligomerization catalyst present, the
more .alpha.-olefins that will be produced for a given amount of
polymerization, and so the concentration of .alpha.-olefins in the
process will be higher, particularly under equilibrium conditions
in a continuous process. If the oligomerization step and
copolymerization step are done separately, the larger the amount of
.alpha.-olefins added per amount of copolymerization catalyst
present, the higher the branching level will be.
[0048] In turn the branching level affects the density of the
resulting polyolefin. This higher branching level usually the
lowers the density of the resulting polyolefin. Preferably the
density is less than 0.89 g/mL, more preferably less than 0.88
g/mL, especially preferably less than 0.87 g/mL and very preferably
less than 0.86 g/mL. When the copolymer is a "solid", i.e. can hold
its shape for the test, density is measured by ASTM Method D792-08,
Method A. When the copolymer is a "liquid", i.e. flows too much for
the D792-08 test, the density is measured using ASTM Method
D4052-09 at a temperature of 23.degree. C. A preferred minimum
density is 0.80 g/mL. It is to be understood that a preferred
density range may be formed from any preferred minimum and maximum
density.
[0049] It is preferred that the polyolefin described herein have a
VI of about 125 or more, more preferably about 140 or more, and
very preferably about 150 or more. VI is measured by ASTM Method
D2270-04.
[0050] The choice of the desired SFC is somewhat complex. It is
believed that to achieve a relatively high VI the branches on the
polymer should be relatively long, but if the branches are very
long they themselves may have a tendency to crystallize, thereby
possibly having a deleterious effect on low temperature properties
such as pour point. Short branches are believed to be relatively
ineffective in increasing VI. Therefore the desired SFC will often
be a compromise between these and other factors. The higher the SFC
the larger the proportion of relatively long chain .alpha.-olefins
produced, and hence long branches incorporated into the polyolefin.
The lower the SFC the relatively higher amount of short chain
.alpha.-olefins produced and the short branches incorporated into
the polyolefin. A preferred SFC range is about 0.50 to about 0.90,
more preferably about 0.55 to about 0.85.
[0051] Another factor to be considered in synthesis of the
polyolefin is the level of branching of the polyolefin. As noted
above the higher the branching level, the lower the density. Lower
densities mean decreased crystallinity from ethylene segments in
the main chain until, eventually the crystallinity has been reduced
to a level where the polyolefin may be amorphous (an elastomer).
For improved lower temperature properties of the lubricant or
lubricant additive, it is usually preferred that the polyolefin
exhibit lesser amounts of crystallinity. Determination of the
branching level of the polymer in mole percent .alpha.-olefin
incorporated is complicated by the fact that a series of
.alpha.-olefins is produced and incorporated into the polyolefin in
the process. Generally speaking it is impossible to distinguish by
.sup.13C NMR between branches having 10 or more carbon atoms, and
on most NMR equipment between branches having 6 or more carbon
atoms. However one can calculate what the branching level should be
based on the SFC of the oligomerization catalyst and the amount of
methine carbon atoms in the polyolefin, which may be readily
determined by NMR.
[0052] One first calculates the average branch length in the
polyolefin using the SFC, on the assumption that all
.alpha.-olefins are incorporated into the polyolefin in the same
molar proportions in which they are produced by the oligomerization
catalyst. Average branch lengths for selected SFCs are shown in
Table 1.
TABLE-US-00001 TABLE 1 SFC Avg. Branch Length 0.45 3.6 0.55 4.4
0.65 5.7 0.75 8.0 0.85 13.3 0.95 39.9
These average branch lengths are obtained by calculating the mole
percent of each branch length obtained, multiplying that by the
number of carbon atoms in that branch (which contains two fewer
carbon atoms than the corresponding .alpha.-olefin), and then
adding this value for each of the branches. This sum is the average
branch length.
[0053] As can be seen from Table 1, an SFC of 0.75 gives an average
branch length that happens to correspond to the branch length in
poly-1-decene, 8 carbon atoms. However it should be noted that
because a range of .alpha.-olefins is produced, 25% of the branches
are ethyl (2 carbons), and 1.06 mole percent of the branches have
24 carbon atoms, with lesser amounts of longer branches.
[0054] Using the average branch length as calculated above for any
SFC of an oligomerization catalyst, one can then calculate the
branching level. One measures the total methine carbon atoms per
1,000 carbon atoms present. For this example we will assume it is
60, and the SFC is 0.75. This would mean in 1,000 carbon atoms
there were 600 carbon atoms "contributed" by the .alpha.-olefins
which formed branches (10 carbon atoms per .alpha.-olefin times 60
branches), and the remainder of 400 carbon atoms were derived from
ethylene. Therefore the molar ratio of ethylene:.alpha.-olefin
incorporated is 200:60, so the branching level is 23.1
[(60/260).times.100] mole percent. Analogous calculations can be
carried out at other methine carbon atoms levels and SFC values.
This calculation is the definition of "mole percent branching
level" herein.
[0055] It is preferred that the minimum mole percent branching
level is 5%, more preferably 10%, very preferably 15%, and
especially preferably 20%. A preferred maximum mole percent
branching level is 40%, more preferably 35%, very preferably 30%,
and especially preferably 25%. It is to be understood that any
preferred minimum mole percent branching level may be combined with
any maximum mole percent branching level to form a preferred mole
percent branching level range.
[0056] The polyolefin of the present invention has a relatively low
melting point or no melting point, and the crystallinity level is
generally low or nil. Thus, generally gas phase or liquid
suspension polymerization may be used to produce a polyolefin in
the higher part of the density range, liquid solution
polymerization will most likely be preferred method for carrying
out the oligomerization and polymerization parts (simultaneously or
sequentially) of the process. Solution
oligomerization/polymerizations of these types are well known, see
for instance Y. V. Kissin, Polyethylene, Linear Low Density,
Kirk-Othmer Encyclopedia of Chemical Technology (online), John
Wiley & Sons, DOI 10.1002/0471238961.10209149511091919.a01.pub2
(2005), which is hereby included by reference for the
polymerization, and for the separate oligomerization see U.S. Pat.
Nos. 6,103,946, 6,534,691, 7,053,259, 7,049,442 and 7,053,020, and
World Patent Applications 1999/012981 and 2000/050470, all of which
are hereby included by reference.
[0057] It is preferred that the polymerization and oligomerization
be carried out simultaneously in a vessel. Conditions which are
mutually applicable to both the polymerization and oligomerization
catalysts may be used. For instance the temperature may be in the
range of about 60.degree. C. to about 150.degree. C., and a
mutually useable solvent such as an alkane or mixture of alkanes
and/or an aromatic hydrocarbon may be used. Many
activators/cocatalysts are useful for both of these types of
catalysts, such as alkylaluminum compounds, for instance
methylaluminoxane. If the process is a solution process wherein
oligomerization and polymerization are done simultaneously it may
be advisable to add the oligomerization catalyst to the vessel
first to build up a supply of olefins in the process before adding
the polymerization catalyst so that higher melting polyethylene is
not formed before the process reaches steady state. The higher
melting polyethylene may foul the vessel by precipitating, before
the .alpha.-olefin concentration in the vessel builds up to produce
the lower melting (and lower density) desired polyolefin.
[0058] If the oligomerization and polymerization parts of the
process are done sequentially, conditions for the oligomerization
and polymerization may be different, conditions suitable for each
type of catalyst being used in that part of the overall process.
After the oligomerization is done the stream of the series of
.alpha.-olefins can be treated in a number of ways, for instance
solvent may be removed, the oligomerization catalyst be
deactivated, or the stream of .alpha.-olefins be partially
fractioned to remove, for instance, lower boiling compounds (under
this condition a mole percent branching cannot be calculated as
shown above). The .alpha.-olefin stream is preferably added as a
liquid to the polymerization part of the process.
[0059] The Mn (number average molecular weight of the polyolefin is
preferably in the range of about 300 to about 20,000. The Mn is
measured by standard methods using Size Exclusion Chromatography
(some called Gel Permeation Chromatography) using a linear
polyethylene standard. A more preferred minimum Mn is about 1000,
especially preferably about 2000. A more preferred maximum Mn is
about 15,000, more preferably about 10,000 and very preferably
about 5,000. It is to be understood that any preferred minimum Mn
may be combined with any preferred maximum Mn to form a preferred
Mn range for the polyolefin. The molecular weight of the polyolefin
may be controlled to some extent by the polymerization conditions,
but may also be controlled by the addition of a compound which can
decrease Mn, such as the commonly used hydrogen. Hydrogen has the
advantage, if one does not want unsaturation in the polyolefin, of
producing a saturated polymer end when it causes chain
transfer.
[0060] After the polyolefin has been formed it may undergo
treatment, chemical and/or physical to make more suitable component
in a lubricant. In most cases it would be desirable to remove any
solvent or other liquid from the polyolefin formed in the
polymerization process, and to remove, to the practical extent
possible any unreacted .alpha.-olefins in the polyolefin. Both of
these may be accomplished by distilling or otherwise volatilizing
the solvent and .alpha.-olefins. Other treatments may also be done,
for instance it may be fractionated so that only a certain
molecular weight portion is used, and/or it may be hydrogenated to
remove unsaturation, and/or treated with activated carbon to remove
color. Other similar treatments known for PAOs in the art may also
be used. It is preferred that the polyolefin is not treated to add
(as by grafting) polar groups, as to make, for instance, the
polyolefin useful as a dispersant. If suitable the polyolefin may
be used without post treatment in a lubricant or lubricant
additive.
[0061] As noted above PAOs are usually made from previously
synthesized, and often purified, .alpha.-olefins, such as 1-octene,
and/or 1-decene and/or 1-dodecene. These olefins are significantly
more expensive than ethylene from which they are usually made. The
present process makes the olefins that are copolymerized with
ethylene in situ, especially when the oligomerization and
polymerization are simultaneous in a single vessel. This saves
considerable cost in the manufacture of the polyolefin.
[0062] It is theorized that the presence of ethylene repeat units
in the polyolefin also helps the low temperature properties of the
polyolefin when it is used as a lubricant component. For instance
the range of branch lengths in the polyolefin, as opposed to a
polymer with only one or two branch lengths in it, may help slow
the crystallization of longer branches, another potential
improvement in low temperature properties. This may improve low
temperature properties such as pour point. According to J.
Brandrup, et al., Ed., Polymer Handbook, 2.sup.nd Ed., John Wiley
& Sons, New York (1975), p. II-143 to II-144, the glass
transition temperature (Tg) polyethylene is -125.degree. C., while
the Tg of poly-1-decene is -41.degree. C. and the Tg of
poly-1-dodecene is -32.degree. C. It would be expected for the
present polyolefin to have a Tg lower than that of either
poly-1-decene or poly1-1dodecene since Tg's of copolymers generally
are intermediate between those of the consistent monomer's
polymers. Again this may improve low temperature properties such as
pour point.
[0063] In lubricants, the polyolefins of the present invention are
particularly useful as base oil or a viscosity index improver. For
instance, the present polyolefin may be part of a lubricant
additive that improves the VI of an already formulated lubricant.
Use as a base for the lubricant may also help improve the lubricant
VI.
[0064] The present invention is not limited to the embodiments
described and exemplified above, but is capable of variation and
modification without departure from the scope of the appended
claims.
* * * * *