Note: Descriptions are shown in the official language in which they were submitted.
WO 95/27746 2187233 PGT/US95/04250
APPLICATION FOR E&TENT
Tifle: ETHYLENE a-OLEFIN BLOCK COPOLYMERS AND
METHODS FOR PRODUCTION THEREOF
Technical Field
This invention relates to block polymers containing both crystalline and
elastomeric blocks. The copolymers have blocks of polyethylene optionally
containing
an a-olefin and a non-conjugated diene and blocks containing ethylene and an a-
olefin.
A novel process for producing the block copolymers is also provided.
BACKGROUND
Block copolymers are well known. They have been used commercially as
components in adhesives, as melt processable rubbers, in impact resistant
thermoplastics,
as compatibilizers, as "surfactants" for emulsifying polymer-polymer blends,
and as
viscosity index improvers in lubricating oils. A block copolymer is created
when two or
more polymer molecules of different chemical composition are covalently bonded
in an
end-to-end fashion. While a wide variety of block copolymer architectures are
possible,
most block copolymers of interest involve the covalent bonding of hard plastic
blocks,
which are substantially crystalline or glassy, to elastomeric blocks forming
thermoplastic
elastomers. Other block copolymers, such as rubber-rubber (elastomer-
elastomer),
glass-glass, and glass-crystalline block copolymers are also possible and may
have
commercial importance. Two common types of block copolymer structures are the
diblock and tri-block forms. However, multi-block copolymers, in which more
than
three blocks are bonded together, are also desirable. The multi-block
copolymers
include either linear multi-block or multi-arm star block polymers.
Tri-block and multi-block copolymers containing "hard" and "soft" blocks have
WO 95/27746 2187233 PCT/US95/04250
- 2 -
the unique ability of behaving as thermoplastic elastomers, combining
thermoplasticity
with rubber-like behavior. The typical requirement for achieving thermoplastic
elastomeric behavior is the ability to develop a two-phase physical network.
Such a
system is composed of a portion of hard block, having a glass transition
temperature
(Tg) or melting temperature (Tm) above the service temperature of a fabricated
end use
product, and a portion of a soft block, having a Tg below the service
temperature. The
hard blocks associate to form domains that serve as physical crosslinks and
reinforcement sites. The reinforcement sites and physical cross-links are
thermally
reversible, making it possible to process the polymer as a melt phase material
at
temperatures above the Tg or Tm of the hard block. Among the advantages of
having a
physically cross-linked system that is thermally reversible is that while
below the Tg or
Tm of the hard block such polymers exhibit properties approaching those of
fully-cured,
i.e. chemically crosslinked elastomers, but unlike such cured elastomers, by
heating these
polymers above Tg or Tm of the hard block, the physical crosslinks are
eliminated and
the material can be processed. The advantage of such systems will be well
known to
those of ordinary skill in the art.
A substantial amount of work has been done in an attempt to synthesize
olefinic
block copolymers. The ideal catalyst system would produce a"living polymer".
Unlike
typical Ziegler-Natta polymerization processes, living polymerization
processes involve
only initiation and propagation steps and essentially lack chain terminating
side reactions.
This permits the synthesis of the predetermined and well-controlled structures
desired in
a block copolymer. A polymer created in a"living" system can have a narrow or
extremely narrow distribution of molecular weight and be essentially
monodisperse.
Living catalyst systems are characterized by an initiation rate which is on
the order of or
exceeds the propagation rate, and the absence of termination or transfer
reactions. In
addition, these catalyst systems are preferably characterized by the presence
of a single
type of active site. To produce a high yield of block copolymer product in a
polymerization process the catalyst must exhibit living characteristics to. a
substantial
extent.
Anionic polymerization routes to ideal block copolymers have been studied.
Butadiene-isoprene block copolymers have been synthesized using the sequential
monomer addition technique. In sequential addition, a certain amount of one of
the
monomers is contacted with the catalyst. Once a first such monomer has reacted
to
substantial extinction forming the first block, a certain amount of the second
monomer or
CA 02187233 2004-11-17
- 3 -
monomer species is introduced and allowed to react to form the second block.
The
process may be repeated using the same or other anionically polymerizable
monomers.
Ethylene and other a-olefins, such as propylene and butene, are not directly
block
polymerizable by anionic techniques.
U.S. patent 4,804,794 to Ver Strate, et al., discloses segmented'copolymers of
ethylene and at least one other alpha-olefin. The copolymers have a narrow MWD
(Mw/Mn) less than 2. The copolymers have one segment that is crystallizable
and at least
one low crystallinity segment. A vanadium catalyst is utilized with an
organoaluminum
cocatalyst. The polymerization is carried out in a mix-free reactor.
WO 9112-285-A to Turner, et al., discloses a process for production of block
copolymers of ethylene with an alpha-olefin and the polymer produced by the
process.
The process includes sequentially contacting ethylene with an alpha-olefin in
the
presence of an ionic catalyst to produce a block copolymer. The ionic catalyst
comprises
the reaction product of a first component which is a bis (cyclopentadienyl)
derivative of a
metal of Group IV-B of the Periodic Table of the Elements which metal is
capable of
forming a cation formally having a coordination number of 3 and a valence of -
4; and at
least one second component comprising a cation capable of donating a proton
and a
compatible non coordinating anion.
While many patents and publications claim the Ziegler-Natta catalyzed
synthesis
of block copolymers from ethylene and propylene, there is little evidence that
these
products were obtained in high purity. In Boor, J. Ziegler-Natta Catalysts and
Polvmerization. Academic Press, 1979, Boor states that the known kinetic
features of
heterogeneous Ziegler-Natta catalysts suggest that it is unlikely that block
polymers
were synthesized in a substantial yield, as compared to the total polymer
formed.
In this context, several dithculties arise in the use of known coordination
catalysts for the block copolymerization of a-olefins. Among those are the
fact that
conventional catalysts are typically multi-sited, and a significant fraction
of the active
sites are unstable. This leads to non-uniform chain initiation and termination
which, in
turn, lowers the theoretical block copolymer yield. In addition, chain
transfer rates
during polymerization with known coordination catalysts are high. This is
especially true
with metallocene catalyst systems where thousands of chains may be produced
per active
WO 95/27746 21$ 72 3 3 PCT/US95/04250
- 4 -
site.
SUMMARY
The present invention is directed to procedures to make the use of certain
coordination catalysts possible for production of alpha-olefin block
copolymers of the
crystalline-elastomeric type in high purity. These block copolymers and
methods of their
manufacture by a Ziegler-Natta type catalyst are objects of our invention. We
will
demonstrate the existence of high yields of true block copolymers. Evidence of
the
existence of such high yield of true block copolymer, as stated above, has
been
substantially absent prior to the present invention.
The present invention comprises a novel block polymer having an A block and a
B block, and if a diene is present in the A block, a nodular polymer formed by
coupling
two or more block polymers. The A block is an ethylene polymer optionally
containing
an alpha-olefin and /or a non-conjugated diene. The diene, if present in the A
block, is
present in an amount up to 10 mole percent based on the total moles of the
monomers
of the block copolymer. The B block has a first polymer segment that is an
ethylene and
an alpha-olefin copolymer segment, the first polymer segment is contiguous to
a junction
of the A block and the B block. The B block may have a tip segment, the tip
segment is
fiirthest from the A B junction, and the tip segment is a polymer of ethylene
and an
alpha-olefin. The tip segment of the B block may comprise an ethylene, alpha-
olefin
copolymer with an average ethylene content of at least 60 mole percent based
on the
total tip segment, the tip segment melts in the range of from 35 C to 130 C
as
measured by DSC.
The present invention also comprises a process for producing these block
copolymers,
which has the steps of
3 0 (a) Forming a catalyst species by premixing a vanadium compound and an
organoaluminum compound. The pre-mixing step is carried out for a sufficient
period of
time to provide an adequate amount of active catalyst species;
(b) Feeding the reaction product of step (a) to a niix free reactor
concurrently
with a monomer stream made up of ethylene, optionally an alpha-olefin and
optionally a
non-conjugated diene;
WO 95/27746 2 18 7 2 3 3 pCT/US95/04250
- 5 -
(c) Feeding at least a second monomer blend made up of ethylene, and an alpha-
olefin,
If a diene is present, the block copolymer may be coupled using the residual
olefinic functionality of the diene to produce nodular polymers. Coupling can
take place
either in the reactor, or post reactor.
The coupled polymer will generally be useful in, among other appGcations,
lubricating
oils, as viscosity iinprovers or dispersants. A coupling agent may be used to
couple two
or more block copolymers.
These block copolymers find use as thermoplastic elastomers (TPE), plastics
blending
components, in fuel lubricating and heating oils, as a bitumen modifier, in
roof sheeting
compounds, and in hot melt adhesives.
These and other features, aspects and advantages of the present invention will
become
better understood with reference to the following description, appended claims
and
accompanying drawings where:
BRIEF DESCR.iMON OF THE DRAWINGS
Figure 1 is a Differential Scanning Calorimeter (DSC) thermogram for polymer
2A described in Example 2.
Figure 2 is a DSC thermogram for polymer 2B described in Example 2.
Figure 3 is a DSC thermogram of a pure polyethylene A block.
Figure 4 is a schematic representation of a process for producing polymer in
accordance with our invention.
DESCRIPTION OF THE PREFEMU FMBODIMENTS
The present invention is directed to procedures to make and use certain alpha-
olefin block copolymers of the crystalline-elastomeric type in high purity
using certain
WO 95127746 21 8723 3 PCT/uS95/04250
- 6 -
coordinadon catalysts. These block copolymers and methods of their manufacture
by a
Ziegler-Natta type catalyst are among the objects of our invention.
The present invention comprises a novel block copolymer having an A block and
a B block and when a diene is present in the A block, a nodular polymer formed
by
coupling two or more block copolymers. The nodular polymer may optiohally
contain a
coupling agent Y;
(1) "A" denotes a block comprising polyethylene, and optionally an a-olefin
comonomer not exceeding 5 mole percent based on the total moles of monomers
in the A block, and further optionally containing up to 10 mole percent of a
non-
conjugated diene. The diene is present at this mole percent based on the total
A
B block copolymer.
The A block is present in the block copolymer preferably in the range of from
5
to 90 weight percent based on the total weight of the block copolymer. More
preferably
in the range of from 10 to 60 weight percent, most preferably in the range of
from 20
to 50 weight percent.
(2) "B" denotes a block comprising ethylene and an a-olefin copolymer. The B
block comprises one or more segments. If there is one segment in the B block,
it
will be an ethylene, a-olefin segment. If there are two or more segments in
the B
block, the first segment immediately following the junction of the A and B
blocks
will be an ethylene a-olefin copolymer segment. The tip or end segment will be
located in the portion of the B block furthest from the A B junction. If there
are
two segments, the second or tip segment will be an ethylene, a-olefin
copolymer
with an average ethylene content of at least 60 mole percent based on the
total
moles of the monomers of the tip segment, and which melts in the range of 3 5
to
130 C, as measured by DSC.
Optionally the B block has an intramolecular composition distribution such
that
at least two portions of the B block, each portion comprising at least 5
weight percent of
the B block, differ in composition by at least 5 weight percent ethylene. The
B block is
present in the block copolymer in the range of from 10 to 95 weight percent
based on
the total weight of the block copolymer.
WO 95/27746 PGT/US95104250
2187233
- 7 -
The tip of the B block can comprise up to 50 weight percent of the B block,
preferably in the range of from 3 to 20 weight percent, more preferably in the
range of
from 5 to 15 weight percent, all weight percents of the tip based on the total
weight of
the B block. The tip segment, when present, is typically the segment furthest
from the A
B junction.
Y is a coupling agent which has reacted with the residual olefinic
functionality in
the block polymers and has coupled two or more block polymer molecules.
A is a crystalline block and B has elastomeric segments. B may optionally
contain
a low level of crystallinity.
COPOLYME ,L~B AICKS
BI,OCK...~
Block A comprises polyethylene which optionaHy may contain up to 10 mole
percent of a non-conjugated diene (based on the total moles of the monomers of
the A B
copolymer). The A block may optionally contain an a-oleSn comonomer at a level
not
exceeding 5 mole percent based on the total moles of the monomers of the A
block. If
block A contains a non-conjugated diene it will be present in the A block
preferably in
the range of from 0.01 to 5 mole percent, more preferably in the range of from
0.03 to
2 mole percent, most preferably in the range of from 0.05 to 1 mole percent
based on
the total moles of the monomers of the A B block copolymer. Block A comprises
5 to
90 weight percent of the entire polymer, preferably 10 to 60 weight percent ,
most
preferably 20 to 50 weight percent of the entire polymer. The A block has a T.
of at
least 110 C, preferably at least 105 C, more preferable at least 120 C.
BLOCK B
Block B is an elastomer that comprises an ethylene and an a-olefin copolymer.
Block B optionally has an intramolecular-compositional distribution such that
at least
two portions of the B block, each of said portions comprising at least 5
weight percent
of said B block, differ in composition by at least 5 weight percent ethylene.
Intramolecular-compositional distribution is the compositional variation, in
terms of
ethylene, along the polymer chain or block. It is expressed as the minimum
difference in
CA 02187233 2004-11-17
_$_
average ethylene composition in weight percent of ethylene that exists between
two
portions of a single block, each portion comprising at least 5 weight percent
of the
block. Intramolecular-compositional distribution is determined using the,
procedures
disclosed in U.S. Patent No. 4,959,436,
The B block comprises 95 to 10 weight percent of the total weight of the block
copolymer, preferably 90 to 40 weight percent; more preferably 80 to 50 weight
percent.
The B block comprises one or more segments. If there are two or more
segments in the B block, the tip or end segment fiuthest from the junction of
the A block
and the B block will comprise an ethylene, a-olefin copolymer with an average
ethylene
content of at least 60 mole percent based on the total moles of the monomers
of the tip
segment. The tip segment melts in the range of from 35 C to 130 C as
measured by
DSC
The tip of the B block can comprise up to 50 weight percent of the B block,
preferably in the range of from 3 to 20 weight percent, more preferably in the
range of
from 5 to 15 weight percent, all weight percents of the tip based on the total
weight of
the B block. The tip segment, when present, is typically the segment furthest
from the A
B junction.
The B block can comprise an average ethylene content in the range of from 20
to 90 mole percent, preferably in the range of from 30 to 85 mole percent, and
most
preferably in the range of from 50 to 80 mole percent based on the total moles
of the
monomers of the B block.
The block copolymers of the invention are fiarther characterized in that they
have
a number average molecular weight of between 750 and 20,000,000, and have a
molecular weight distribution characterized by a Mq,/Mn ratio of less than
2.5. The block
copolymers have an n-hexane soluble portion, at 22 C not exceeding 50 weight
percent, preferably not exceeding 40 weight peroent, and more preferably not
exceeding
30 weight percent, based on the total weight of the block copolymer. The
products of
the present invention are further characterized by a relatively small amount
of polymer
chains in the final product that contain only an A block or only a B block.
The presence
of such materials could detract from overall product properties. A typical
characteristic
WO 95/27746 PCT/Us95/04250
21$723 3-
- 9 -
of the preferred product of this invention is that the block copolymer
contains at least 50
% (weight) of the desired A B structure as polymerized. Product purification
is not
necessary to obtain good properties.
Monomers
Alpha-olefins particularly useful in the practice of this invention are those
having
from 3 to 8 carbon atoms, e.g. propylene, butene-l, pentene-I, etc. Alpha-
olefins of 3 to
6 carbon atoms are preferred due to economic considerations. The most
preferred a-
olefin is propylene.
Typical non-limiting examples of non-conjugated dienes useful in the practice
of
this invention are:
(a) straight chain acyclic dienes such as: 1,4-hexadiene; 1,6-octadiene;
(b) branched chain acyclic dienes such as: 5-methyl-1,4-hexadiene; 3,7-
dimethyl-1,6-
octadiene; 3,7-dirnethyl-1,7-dioctadiene; and the mixed isomers of
dihydromyrcene and dihydro-ocinene;
(c) single ring dienes such as: 1,4-cyclohexadiene; 1,5-cyclooctadiene; and
1,5-
cyclododecadiene;
(d) multi-ring fixed and fused ring dienes such as: tetrahydroindene;
methyltetra-
hydroindene; dicyclopentadiene; bicyclo-(2,2,1)-hepta-2, 5-diene; alkenyl,
alkylidene, cycloalkenyl and cycloalkylidene norbornenes such as 5-methylene-2-
norbornene (MNB), 5-ethylidene-2-norbornene (ENB), 5-propenyl-2-
norbornene, 5-(4-cyclopentenyl)-2-norbornene, 5-cyclohexylidene-2-norbornene,
vinyl norbornene, and norbornadiene.
Of the non-conjugated dienes useful in the practice of the invention, dienes
containing at least one of the double bonds in a strained ring are preferred.
The most
preferred dienes are 5-ethylidene-2-norbornene and vinyl-norbornene.
Conjugated dienes
are also contemplated.
CA 02187233 2004-11-17
- 10
-
Polymerization
The novel polymers of our invention are prepared by polymerization in a mix-
fiee
reactor similar to that taught in U.S. Patent No. 4,959,436.
Previously, those of skill in the art thought that a solution polymerization
process
such as that taught in U.S. Patent No. 4,959,436 would not be suitable for
producing
block copolymers such as the ones described above in which one of the blocks,
polyethylene, is insoluble in the solvent. The insolubility could lead to
reactor fouling and
mass transport problems. In turn, these problems could prevent the fonmation
of the
desired well-defined polymer structure and significantly reduce catalyst
efficiency.
Surprisingly, we have found that the block polymers of our invention can be
made in a mix-free reactor when the initial monomer feed consists essentially
of ethylene,
and optionally such that up to 5 mole percent of the A block is alpha olefin
and
optionally a diene sufficient to incorporate up to 10 mole percent of a non-
conjugated
diene (based on the total of the monomers of the block copolymer). This, the A
block, is.
polymerized first. During this part of the reaction, the polyethylene (A)
block may be
only partially soluble in the reaction diluent and the insoluble polymer block
forms a
suspension in the diluent.
Once the polymerization of the A block is substantially complete, one or more
additional monomer feeds are introduced into the reactor containing ethylene,
and an a-
olefin. The reaction of the comonomer mixtures forms the B block of the block
polymer
or the first segment of the B block if there is more than one segment. The B
block is
polymerized onto the polyethylene or A block formed earlier. When this second
part of
the polymerization occurs, there is a noticeable change in the appearance of
the reaction
medium. As the chains become solubilized through the addition of the B block,
the
turbidity of the medium decreases appreciably and the quantity of polymer
particles in
the diluent is markedly reduced. When a tubular reactor is employed, several
monomer
feeds along the reactor length may be used to control the composition and
amount of the
B block and form the segments of the B block. The final feeds to the reactor
may
contain a higher ethyleneJa-olefin ratio to form a semi-crystalline segment at
the tip of
the B block., giving the B block a melting point in the range of from 35 to
130 C.
CA 02187233 2004-11-17
QwAn the pOlymets
Block polymers of our invention may incorporate a diene. The residual olefinic
functionaiity in diene containing block polymers can be reacted with coupling
agents to
produce novel nodular polymers.
Suitable coupling reagents and coupling techinques are described in U.S.
Patent
4,882,406r
Coupling can take place either within the
polymerization reactor or in a post-polymerization reaction. With the diene in
the A
block, the polyethylene segment containing the diene is in a central
polyethylene nodule
with EP block extending outwards.
There are various coupling agents that are capable of reacting with the
residual
unsaturation in the polymer chains to cause coupling of two or more block
polymer
molecules.
. Coupling may be carried out with cationic catalysts such as Lewis acids.
Suitable
Lewis acids may be selected from the group consisting of: AIX3, BX3, SnX4,
SbXs1
AI1YX3õy where y is 0 to 1.5 and R is a hydrocarbon radical, BX4, TiX4 and
mixtures
thereof, where X is selected from the group consisting of chlorine, bromine,
and iodine.
Chlorine is prefeired. For Lewis acids that do not interfere with the
functioning of the
catalyst system used to cany out the polymeriaation, the Lewis acid can be
added
directly to the reactor so that chain coupling oceurs at the same time as the
polymerization. Alternately the coupling agent can be added following the
polymerization.
According to yet another embodiment the coupling agent may be a free radical
catalyst. The free radical catalyst may be a peroxide selected from the group
consisting
of: dicumyl peroxide, di-tertiarybutylperoxide, t-butylperbenzoate, 1,1-di(t-
butylperoxy)-3,3,5-trimethyl cyclohexane, and mixtures thereof Other free
radical
catalysts include azo-bisisobutylnitrile, azodicarboxylate, and mixtures
thereof.
Peroxides can couple non-diene containing portions of the chain and produce a
cross-
linked network. Care must be taken when they are used as coupling agents.
CA 02187233 2004-11-17
- 12 -
In yet another embodiment the coupling agent may be selected from the group
consisting of sulfur dichloride, disulfenyl halides, borane, dithoalkanes,
other sulfur and
accelerated sulfur curatives and mixtures thereot such as
mercaptobenzothiozole,
tetramethyltlnuram disulfide, and butyl zymate. It is apparent that any of the
conventional vulcanization systems useful for EPDM may be employed.
Resins and other reagents may also be employed for coupling. For example alkyl
phenol fonmaldehyde mixtures will couple olefins in certain cases with
catalysts such as
ZnClz , N bromosuccinimide or diphenylbromomethane.
Also contemplated as a coupling mechanism is the use of irradiation or
electron
beams.
For certain non-conjugated dienes, such as norbomadiene, vinyl norbomene,
dicyclopentadiene and tetrahydroindene, both double bonds are polymerizable to
a
greater or lesser extent by the polymerization catalysts of this invention.
With dienes of
this type chains can become cheniically coupled to each other during
polymerization by
reaction of the remaining double bond in an enchained diene monomer with a
growing
chain. This process will lead to coupling of chains in the reactor even in the
absence of a
coupling agent Y.
The efficiency of olefin utilization will detenmine what level of coupling
agent to
use in relation to the amount of diene in the block copolymer. The purpose is
to couple
the diblocks to an extent which yields good mechanical properties but does not
raise
viscosity or produce gel to the extent that the coupled product is not
processable.
The Reaction Solvent
Processes in accordance with the present invention produce copolymers by
polymerization; of a reaction mixture comprised of catalyst, ethylene and at
least one
additional a-olefin monomer and optionally diene. Polymerization in the
presence of a
diluent which has the capability to dissolve a major portion of the final
product is
preferred. Suitable solvents are described in U.S. patent number 4,882,406.
CA 02187233 2004-11-17
- 13 -
Polvmerization Reactor
These processes are carried out in a mix-free reactor system, which is one in
which substantially no mixing occurs betwean portions of the reaction mixture
that
contain polymer chains initiated at different times. Suitable reactors are
disclosed in
U.S. patents 4,959,436 and 4,882,406r
Additional reaction considerations are
also disclosed in these references.
To obtain the desired A B block polymer, it is necessary to add additional
reactants (e.g., at least one of the monomers ethylene, a-olefin or diene)
either at some
point or points along the length of a tubular reactor, or during the course of
polymerization in a batch reactor, or at various points in a train of
continuous flow
stirred reactors. However, it is also preferred to add essentially all of the
catalyst at the
inlet of a continuous flow reactor or at the onset of batch reactor operation
to meet the
requirement that essentiaUy all polymer chains are initiated simultaneously.
To make
diene containing block polymers, diene is fed at the reactor inlet to
incorporate diene
into an A block. IViultiple feeds of ethylene and propylene can be used to
control the
amount and composition of the segments in the B block.
Since the tubular reactor is the prefenred reactor system for carrying out
processes in accordance with the prefened embodiment, the illustrative
descriptions and
examples that follow are drawn to that system, but will apply to other reactor
systems as
will readily occur to those of ordinary skill in the art having the benefit of
the present
disclosure. However, as would readily occur to those of ordinary slcill in the
art having
the benefit of the present disclosure, more than one reactor could be used,
either in
parallel, or in series with multiple monomer feeds to vary intramolecular
composition.
The Catalvst
The composition of the catalyst used to produce ethylene, a-olefin copolymers
has a prof
embodiment should be such as to yield essentially one active catalyst species
in the
reaction mixture. More specifically, it should yield one primary active
catalyst species
which provides for substantially aU of the polymerization reaction. Additional
active
catalyst species could be present, provided that they do not produce a
significant amount
of polymer which detracts from the performance of the polymer produced. Such
CA 02187233 2004-11-17
- 14 -
additional active catalyst species may provide as much as 35% by weight of the
total
copolymer. Preferably, they should account for 10% by weight or less of by the
copolymer. Thus, the essentially one active species should provide for at
least 65% by
weight of the total copolymer produced, preferably for at least 90"/o by
weight thereof.
The extent to which a catalyst species contributes to the polymerization can
be readily
determined using the below-described techniques for characterizing catalyst
according to
the number of active catalyst species. Techniques for characterizing catalyst
according
to the number of active catalyst species are within the skill of the art.
These techniques
are shown in Cozewith, C. and Ver Strate, G., "Ethylene-Propylene Copolymers.
Reactivity Ratios, Evaluation and Significance", MAmmolecules_ 4, 482
(1971),,~:
The preferred catalyst system in practicing processes in accordance with these
embodiments comprises a hydrocarbon-soluble vanadium compound in which the
vanadium valence is 3 to 5 and an organo-aluminum compound, with the provision
that
the catalyst system yields essentially one active catalyst as described above.
At least one
of the vanadium compound/organo-aluminum pair selected must also contain a
valence-
bonded halogen. Vanadium compounds useful in practicing processes in
accordance
with the present invention could be:
WO 95/27746 21vp 723 3 - PGT/U895104250
- 15 -
O (1)
11
VCIx(OR)3.x;
VC1x(COOR)3-x ; (2)
where x 0 to 3 and R = a hydrocarbon radical;
VC14;
0
ii
V(AcAc)z;
V(AcAc)3;
0
VCIX(AcAc)3.x; (3)
where AcAc = acetyl acetonate; and where x=1 or 2; and
VC13.nB;
where n = 2 to 3 and B = Lewis base capable of making hydrocarbon-soluble
complexes with VC13, such as tetrahydrofuran, 2-methyl-tetrahydrofuran and
dimethyl
pyridine. In Fonmulas (1) and (2) above, R preferably represents a C, to Cla
aliphatic,
alicyclic or aromatic hydrocarbon radical such as ethyl (Et), phenyl,
isopropyl, butyl,
propyl, n-butyl, i-butyl, t-butyl, hexyl, cyclohexyl, octyl, naphthyl, etc.
Non-limiting
illustrative examples of formulas (1) and (2) compounds are vanadyl
trihalides, alkoxy
halides and alkoxides such as VOCl3, VOCIz(OBu) where Bu = butyl, VO(OC2H5)3,
and
vanadium dichloro hexanoate. The most preferred vanadium compounds are VCl4,
VOC13, and VOCIz(OR).
As already noted, the co-catalyst is preferably an organoaluniinum compound.
In
CA 02187233 2004-11-17
- 16 -
terms of chemical formulas, these compounds could be as follows:
AIR3 Al(OR')Rz
AIRlX R2AI-O-A1R2
AIRRX
AIAX3
AIRX2 methyl alumoxane
where R and R' represent hydrocarbon radicals, the same or different, as
desczibed above
with respect to the vanadium compound formula and X is a halogen selected from
the
group consisting of bromine, iodine, and chlorine. Chlorine is preferred. The
most
preferred organoaluminum compound for use with a vanadium catalyst is an
aluminum
alkyl sesquichloride such as AL=Et3C13 or A1Z('iBu)3C13. The catalyst and its
effects on the
polymerization are disclosed in U.S. patent 4,882,406. _
With reference again to processes for making copolymer in accordance with our
invention, certain combinations of vanadium and aluminum compounds that can
comprise the catalyst system can cause branching and gellation during the
polymerization
for polymers containing high levels of diene. To prevent this from happening,
Lewis
bases such as ammonia, tetrahydrofuran, pyridine, tributylamine,
tetrahydrothiophene,
tetraalkoxysilane, etc., can be added to the polymerization system using
techniques well
known to those skilled in the art.
Chain transfer reactions during tubular reactor polymerization in accordance
with
our invention broadens polymer molecular weight distribution and causes the
fornation
of undesirable blocks such as A-only polymer or B-only polymer rather than the
desired
A B block copolymers of the present invention. It is desireable to operate at
low
temperature and in the absence of Hydrogen to avoid transfer reactions. U.S.
patent
4,882,406 discloses chain transfer reactions.'
Molecular weight distribution and percent of block polymer in the final
product
are also affected by catalyst deactivation during the course of the
polymerization which
leads to termination of growing chains. Early chain tennination will reduce
the yield of
the desired block copolymers. Deactivation can be reduced by using the
shortest
residence time and lowest temperature in the reactor that will produce the
desired
CA 02187233 2004-11-17
- 17 -
monomer conversions.
Gel Permeation Chromatogaphy (GPC) and several analytical techniques are
used to characterize the polymer and its performance in varlous applications.
These
techniques have been described in several publications notably U.S. Patent No.
4,989,436.,;
Molecular weight and composition ~ts are described in G. Ver Strate, C.
Cozewith, S. Ju, Macromolecules. 21, 3360 (1988). The variety of other
techniques
used are soundly based in polymer structure characterization as descn'bed in
"Structure
Characterization" The Science and Technology of Elastomers, F. Eirich, editor,
Academic Press 1978 Chapter 3 by G. Ver Strate. Differential scanning
calorimetry
(DSC) is used to characterize the block polymers described herein. The
standard
protocol for these analysis is to load the calorimeter at 20 C with a
specimen free of
molding strains, to cool the sample to -75 C, scan to 180 C at 10 C/min.,
cool to -75
C, and re-run the scan. Ti, T. and heat of fusion are evaluated. In some
cases, low
melting crystallinity will not be seen on the second scan as it may take many
hours to
develop even at low temperatures.
Catal, -sPreparation
Polymerizations in accordance with the preferred embodiments should be
conducted in such a manner and under conditions sufficient to initiate
propagation of
essentially all copolymer chains simultaneously. This can be accomplished by
utilizing
the process steps and conditions described in U.S. patent 4,959,436. 25
Reaction Tempgrjture
The temperature of the reaction mixture should also be kept within certain
limits.
The temperature at the reactor inlet should be high enough to provide
complete, rapid
chain initiation at the start of the polymerization reaction. The length of
time the reaction
mixture spends at high temperature must be short enough to minimize the amount
of
undesirable chain transfer and catalyst deactivation reactions. Control of the
reaction
temperature in light of the fact that the reaction is exothermic, is disclosed
in U.S. patent
4,959,436.,
WO 95/27746 218723 3 PCT/US95/04250
- 18 -
Residence Time
Residence time of the reaction mixture in the mix-free reactor can vary over a
wide range. The minimum could be as low as 0.5 seconds. A preferred minimum is
2
seconds. The maximum could be as high as 3600 seconds. A preferred maximum is
900 seconds. The most preferred maximum is 300 seconds.
Process Flow
When a tubular reactor is used the rate of flow of the reaction mixture
through
the reactor should be high enough to provide good mixing of the reactants in
the radial
direction and minimize mixing in the axial direction. Good radial mixing
promotes
homogeneous temperature and polymerization rate at all points in a reactor
cross
section. Radial temperature gradients may tend to broaden the molecular weight
distribution of the copolymer since the polymerization rate is faster in the
high
temperature regions. Those of ordinary skill in the art will recognize that
achievement of
these objectives is difficult in the case of highly viscous solutions. This
problem can be
overcome to some extent through the use of radial mixing devices such as
static mixers
(e.g., those produced by the Kenics Corporation).
For purposes of illustration, we assume that a block copolymer of polyethylene
and of ethylene and propylene (EP) copolymer is to be produced using as
catalyst
components vanadium tetrachloride and ethyl aluminum sesquichloride. The
polymerization is adiabatic, using hexane diluent for both the catalyst system
and the
reaction mixture.
In a preferred embodiment, with reference to the process flow diagam in Figure
4, the premixing device 1 comprises a temperature control bath 2, a fluid flow
conduit 3
and mixing device 4 (e.g., a mixing tee). To mixing device 4, are fed hexane
solvent,
vanadium tetrachloride and ethyl aluminum sesquichloride through feed conduits
5, 6
and 7, respectively. Upon being mixed in mixing device 4, the resulting
catalyst mixture
is caused to flow within conduit 3, optionally in the form of a coiled tube,
for a time long
enough to produce the active catalyst at the temperature set by the
temperature bath.
The temperature of the bath is set to give the desired temperature in conduit
3, at the
outlet of the bath. Upon leaving the premixing device, the, catalyst solution
flows
--- ---- ------------- -
"n'nxc.wrroisz 2 .~ 8 7 2 3 3
-19-
through conduit 8 into mixing zone 9, where it is intinzately mixed with a
stream
contaicting hexane diluent and the monomer to be incarporated into the A
block, in this
case ethyleno; and which is fed through conduit 10. Any sultable mixing device
can be
used such as mechanical mixer, orifice mixer or mixang tee. For economic
reasons, the
miocing tee is preferred. The residence time of the reactiion mixture in
cnixing zone 9, is
kept short enough to prevent significant potymer formation therein before
being fed
through conduit 11 to tubular reactor 12. A}terna#ively, streams 8 and 10 can
be fed
directly to the inlet of reactor 12, if the flow ratea are high enough to
sccomplish the
desired level of intimate mixing. Stream 10, the heatane with dissolved
monomers, may
be cooled upstream of mixing zone 9 to provide the desired feed temperature at
the
reactor inlet.
Tubular, reactor 12 is "wn with intecrnedi,ate feed points 13, 14, and 14a
where
additional monomers (e.g., ethylene and propylene) and/or hexane can be fed to
the
ls reactor for example, feeding at least a second monomer blend comprising an
ethylene
and an a-olefin, at a time of at least 0.1 seconds affter the above step. The
additional
feeds are used to control the composition of the block copolymer. The number
of side
feeds required and the spacing along the reactor length depends on final
poiymer
structure desired VVhile the rea.ctor can be operated adiabatically, external
cooling
means such as a cooling jacket surrounding at least a portion of the reaetor
system 12,
can be provided to maintain reaction mixture temperature vwithin desired
limits.
Having thus described the above illustrotive rcactor system, it will readily
occur
to thase of ordinary skill in the art that many variaakiona can be made within
the scope of
the present inverrtion. For example, the placement and number of multiple feed
sites, the
choice of temperature profile during polymerization and the concentrations of
reactants,
can be varied to suit the end-use application.
Fynctjg iza ' n of the Bl k Cooolvmers
The. polynacrs produced in accordance with the present invention can be
functionalized, i.e., chemically modified, to have at least one functional
group present
within its structure, which funetional group is capable of: (1) undergoing
further
chemical reaction (e,g, daivatization) with other m,ateaiallor (2) imparting
desirable
properties not otherwise possessed by the polymer alone, absent chernical
nwdiScation.
The fuwtional group can be incoTporated into tha hackbone of the polymer or
can be
attached as a pendant group from the polymer backbone. The functional group
typicaUy
AMENDED SHEET
WO 95/27746 2187233 PCT/US95/04250
- 20 -
will be polar and contain hetero atoms such as P, 0, S, N, halogen and/or
boron. It can
be attached to the saturated hydrocarbon part of the polymer via substitution
reactions
or to an olefinic portion via addition or cycloaddition reactions.
Alternatively, the
functional group can be incorporated into the polymer by oxidation or cleavage
of a
small portion of the diene containing portion of the polymer (e.g., as in
ozonolysis).
Useful functionalization reactions include: maleation, halogenation, "ene"
reactions,
reactions with a phenol group, reaction at the point of unsaturation with
carbon
monoxide, reaction by free radical addition or abstraction and reaction by
epoxidation or
chloroamination.
As indicated, a functionalized polymer is one which is chemically modified
primarily to enhance its ability to participate in a wider variety of chemical
reactions than
would otherwise be possible with the unfunctionalized polymer. In contrast, a
derivatized
polymer is one which has been chemically modified to perform one or more
functions in
a significantly improved way relative to the unfunctionalized polymer and/or
the
functionalized polymer. Representative of such functions are dispersancy
and/or viscosity
modification in lubricating oil compositions. The derivatized polymers can
include the
reaction product of the above recited functionalized polymer with a
nucleophilic
reactant, which includes amines; alcohols, amino-alcohols and mixtures
thereof, to form
oil soluble salts, amides, imides, oxazolines, reactive metal compounds and
esters of
mono- and dicarboxylic acids, and anhydrides. Suitable properties sought to be
imparted
to the derivatized polymer include especially dispersancyõ but also
multifunctional
viscosity modification, antioxidancy, friction modification, antiwear,
antirust, anti-seal
swell, and the like.
Ash-producing detergents can be made using the functionalized polymers of the
present invention as exemplified by oil-soluble neutral and basic salts of
alkali or alkaline
earth metals with alkyl phenols, alkyl sulfonic acids, carboxylic acids, or
organic
phosphorus acids characterized by at least one direct carbon-to-phosphorus
linkage such
as those prepared from the functionalized olefin polymer of the present
invention with a
phosphorizing agent such as phosphorus trichloride, phosphorus heptasulfide,
phosphorus pentasulfide, and sulfur, white phosphorus and a sulfur halide, or
phosphorothiotic chloride. Preferred ash-producing detergents which can be
derived
from the functionalized polymers of the present invention include the metal
salts of alkyl
sulfonic acids, alkyl phenols, sulfurized alkyl salicylates, alkyl
naphthenates and other oil
soluble mono- and dicarboxylic acids.
WO 95/27746 2 1 8 7 23' J PGT/[JS95/04250
~...
- 21 -
The derivatized polymer compositions of the present invention, can be used as
ashless dispersants in lubricant and fuel compositions. Various types of
ashless
dispersants can be made by derivatizing the polymer of the present invention
and are
suitable for use in the lubricant compositions. The following are
illustrative:
1. Reaction products of functionaliaed polymer of the present invention
derivatized
with nucleophitic reagents such as amine compounds, e.g. nitrogen containing
compounds, organic hydroxy compounds such as phenols and alcohols.
2. Reaction products of the polymer of the present invention functionalized
with an
aromatic hydroxy group and derivatized with aldehydes (especially
formaldehyde) and
amines especially polyalkylene polyamines, through the Mannich reaction, which
may be
characterized as "Mannich dispersants".
3. Reaction products of the polymer of the present invention which have been
functionalized by reaction with halogen and then derivatized by reaction with
amines
(e.g. direct amination), preferably polyalkylene polyamines.
The functionalized polymers, particulariy acid functionalized polymers, of the
present invention can be reacted with alcohols, e.g., to form esters.
Procedures are well
known for reacting high molecular weight carboxylic acids with alcohols to
produce
acidic esters and neutral esters. These same techniques are applicable to
preparing esters
from the functaonalized polymer of this invention and the alcohols described
above. The
hydroxy aroniatic functionalized polymer aldehyde/amino condensates useful as
ashless
dispersants in the compositions of this invention include those generally
referred to as
Mannich condensates. A useful group of Mannich Base ashless dispersants are
those
formed by condensing phenol fimctionalized polymer with fonmaldehyde and
polyethylene amines, e.g., tetraethylene pentamine, pentaethylene hexamine,
polyoxyethylene and polyoxpropylene amines, e.g., polyoxyproylene diamine and
combinations thereof.
A useful class of nitrogen containing condensation products for use in the
present
invention are those made by a "2-step process" as disclosed in U.S. Patent No.
4,273,891. Condensates made from sulfur-containing condensates are described
in U.S.
Patent Nos. 3,368,972; 3,649,229; 3,600,372; 3,649,659; and 3,741,896 These
patents
CA 02187233 2004-11-17
- 22 -
also disclose sulfur-containing Mannich condensates. Useful reactive metals or
reactive
metal compounds are those which will form metal salts or metal-containing
complexes
with the functionalized polymer.
The polymer of the present invention may be used as a component of a synthetic
base oil. The functionalized polymer, in addition to acting as intermediates
for dispersant
can be used as a molding release agent, molding agent, metal working
lubricant, thickeners and the like. The additives of the present invention are
primarily
useful in lubrication oil compositions which employ a base oil in which the
additives are
dissolved or dispersed therein. Such base oils may be natural or synthetic.
Base oils
suitable for use in preparing the lubrication oil composition of the present
invention
include those conventionally employed as crankcase lubricating oils for spark-
ignited and
compression-ignited intemal combustion engines, such as automobile and truck
engines,
marine and railroad diesel engines, and the like.
Lubricating oil formulations containing the additives of the present invention
conventionally contain other types of additives that contribute other
characteristics that
are required in the formulation. Typical of such other additives are
detergent/'inhibitors,
viscosity modifiers, wear inhibitors, oxidation inhibitors, corrosion
inhibitors, friction
modifiers, foam inhibitors, rust inhibitors, demulsifiers, lube oil flow
improvers, and seal
swell control agents, etc.
APPLICATIONS
Use in Lubricatinst Oils
The novel block copolymers of the invention may be used as viscosity modifiers
or with suitable functionalization and/or derivatization, as multifunctional
viscosity
modifiers, and as dispersants, for lubricating oils. This is especially true
for block
polymers where there is a diene in the A block, and the polymers are in turn
coupled to
form a nodular polymer. From studies of hydrogenated block polymers of
polyisoprene
and polybutadiene, those of ordinary skill in the art are aware that such
structures lead to
good viscosity-temperature behavior (Ver Strate, G., Struglinski, M.,
"Polymers as
Rheology Modifiers," Schulz, D. & Glass, J., ed. ACS Symp. 462, p. 257, 1991).
Use
of block copolymers are disclosed in. U.S. patent 4,959,436, -
With further modification
CA 02187233 2004-11-17
- 23 -
such block copolymers are usefuI as multifunctional viscosity modifiers as
disclosed in
U.S. Patent No. 5,210,146.;
Copolymer products made in accordance with the present invention when
dissolved in oil have excellent low temperature properties which makes them
suitable for
lube oil applications. Accordingly, lube oil compositions made in accordance
with the
present invention preferably have a IVyni Rotary Viscosity (MRV) measurement
in
centipoise (cps) at -25 C according to ASTM D 3829 of less than 30,000. A more
prefened MRV is less than 20,000, with less than 10,000 being most preferred.
Other Uses of Block Co~olMers
Plastics Blendinst
Impact modification of thermoplastics is commonly achieved by forming a
rubber/plastic blend composition. For this application, it is desirable to
have rubber that
is in pellet form. This is accomplished in the case of ethylene/propylene
rubbers by
adjusting the polymer composition so that it is rich enough in ethylene
content to be
semicrystalline. At that composition (- 70 weight percent ethylene) the glass
transition
temperature of the polymer is raised by some 10 C above its value of -55 C at
45 weight
percent ethylene. Because of this elevated Tg and raised modulus due to
crystallinity,
the blend of polypropylene and EP does not have its optimum lowest ductile-
brittle
transition. By preparing the polymer of this invention, it is possible to
render the
polymer pelletizeable via the PE blocks with the elastomeric B block having
low T.
which gives optimum low temperature properties. In impact modified blends of
high
density polyethylene or of polypropylene which can be used in film or other
finished
goods, it is advantageous to have an agent which stabilizes the morphology of
the
thermoplastic/rubber blend. Polymers of this invention exhibit compatibilizer
activity in
such blends. A given small particle size can be obtained with reduced mixing
energy and
with their morphology stabilized against ripening or coarsening.
Fuel and Heating Oils
Fuel and heating oils contain wax which plugs pipes and filters if the wax
crystallizes into anisotropic needles or platelets. The polymers of this
invention with an
WO 95/27746 2187233 PCTIUS95/04250
- 24 -
oil soluble B block and a PE A block which nucleates wax crystallization cause
granular
crystals to form when added to waxy fuels or heating oil , which crystals do
not plug the
delivery system.
Hot Melt Adhesives
Block polymers are employed in hot melt adhesives. Heretofore, it has not been
possible to obtain polyethylene/propylene polymers with softening points above
100 C
which also maintains a low Tg. PE/EP block polymers of this invention can
provide such
perfonmance.
Bitumen Modification
The bitumen employed in asphalt paving flows during service leading to
"rutting"
on highways. This problem can be eliminated by incorporating polymers to
provide
resilience. The polymers of the present invention are useful in this
application as they
can be supplied as pellets or crumbs. Once in the asphalt, the PE blocks
provide
reinforcement and physical crosslinks to give the binder an elastic network-
like response.
The preferred embodiment of the present invention and the preferred methods of
maldng and using it have been detailed above. Those reading the embodiments
should
understand that the above description is illustrative, and that other
embodiments of the
invention can be employed without departing from the full scope of the
invention as set
forth in the claims that follow.
The invention is further described by the following examples:
Prgparation of Uncoupled Block Polymers
x 1 1
Polymerization was carried out in a 0.793 cm diameter tubular reactor with
hexane as the reaction diluent. The reactor contained a series of feed inlets
along its
length. In this example, A B block polymers are formed. The A block is
polyethylene
(PE) and in runs 1A and 1B the B block is an ethylene/propylene copolymer
(EP). These
polymers were produced using VC 14 catalyst and A12Et3C 13 (EASC) co-catalyst.
The
WO 95/27746 PGT/US95/04250
2187233
- 25 -
catalyst and co-catalyst were fed into a mixing tee as dilute solutions in
hexane at a
temperature of 10 C. After mixing, the combined catalyst components flowed
through
a tube with a residence time of 10 seconds at 10 C before entering the
reactor. The
monomer feed to the reactor inlet was a solution of ethylene in hexane at 20 C
which
was mixed with the catalyst stneam to start the polymerization. The reactor
was
operated adiabatically so that temperature increased along its length.
After a residence time of 0.024 minutes, during which the block A
(polyethylene)
was formed, a feed of ethylene and propylene dissolved in hexane was added via
a
sidestream injection point to begin polymerization of the B block. Two more
ethylene-
propylene side feeds were added at residence times of 0.064 and 0.1 minutes to
increase
the length of the B block. The polymerization was quenched with isopropanol at
the end
of the reactor. The final reaction temperature was 22 C.
In Examples lA and 1B no diene was used and the polymerization was quenched
at 0.14 niin. The reaction conditions of polymerizations 1A and 1B are shown
in Table
1.
Runs IA and 1B
A number of polymerization experiments were carried out at the conditions used
in runs 1A and 1B, but with a polymerization quench injected into the reactor
at a
residence time of 0.024 min. so that only polyethylene was produced. From the
amount
of polymer collected in a known period of time, it was deterniined that close
to 100% of
the ethylene fed to the reactor in the main flow had reacted to form
polyethylene. Thus
in Examples 1A and 1B, the rate at which the polyethylene A block is produced
is equal
to the feed rate of ethylene in the main flow. The rate at which the
elastomeric B block
is produced can be found by subtracting the A block production rate from the
measured
total polymerization rate. The percentages of A and B block in the polymer are
then
calculated by dividing the respective polymerization rates of these blocks by
the total
polymerization rate. The average ethylene content of the polymer is equal to
the
ethylene content of the A block, which is 100%, times the fraction of the A
block in the
polymer, plus the ethylene content of the B block times the fraction of B
block in the
polymer. Thus the ethylene content of the B block can be calculated from the
measured
average ethylene content of the whole polymer and the polymerization rates
from the
equation:
WO 95/27746 2187233 - 26 - PCT/US95/04250
Ethylene content of B block, weight percent = (average polymer %
ethylene content - 100 x weight fraction of A block in the total
polymer)/weight fraction of B block in the total polymer (all terms are in
weight units)
The ethylene content of the entire polymer was determined by infrared
spectroscopy using the calibration described in I. J. Gardner, C. Cozewith,
and G.
Ver Strate, Rubber Chemistrv and Technoloav, vol. 44, 1015, 1971.
The calculated polymer composition is shown in Table 2 along with other
measurements of the polymer structure (GPC and DSC). Of particular note is the
narrow MWD of the polymers.
Tensile properties of the polymers produced were determined in the following
manner. A sheet of polymer 15x 15x0.2 cm was prepared by compression molding
for 15
minutes at 150 C. An aluminum mold was used with Teflon coated aluminum foil
used as a release agent. Dumbbell-type specimens were die cut from the sheet.
These
specimens in tura were strained in tension at a crosshead speed of 12.5
cm/min. Initial
jaw separation was 5 cm. with 3.3 cm of the specimen undergoing most of the
deformation between the fiducial marks. Data were collected at 20 C.
Engineering
modulii were calculated as force at a given percent elongation divided by the
original
unstrained specimen cross-sectional area.
Table 3 shows the modulii and tensile strength of the polymer for runs IA and
lB.
The mechanical properties are a function of molecular weight and the
polyethylene block
content. The modulus of the polymer containing the larger amount of PE block
(lA) are
slightly higher than that with a somewhat lower polyethylene block content
(1B).
ExMIe 2
A second series of polymerization runs were conducted following the procedures
outlined in Example 1. The initial monomer feed to the reactor contained only
ethylene
to produce the polyethylene A block, two side stream feeds were then added to
make the
B block. A final feed was introduced with a high ethylene content to produce a
semi-
3 5 crystalline EP segment at the end or tip of the B block. Reaction
conditions for runs 2A
and 2B are shown in Table 1. In example 2A, a higher initial ethylene feed
rate was used
WO 95/27746 PCT/US95/04250
2187233
- 27 -
than in Example 2B to give the polymer a higher molecular weight and a greater
percentage of A block.
These polymers were characterized in a manner similar to the polymers produced
in Example 1. The results of these analyses are listed in Table 2. The
semicrystalline end
segment of the B block of Example 2A averaged 72.2 weight percent ethylene,
while the
semicrystalline end segment of the B block of Example 2B averaged 70 weight
percent
ethylene. DSC analysis of the polymers, as shown in Figures 1 and 2, show that
the
polymers contain a semi-crystalline firaction melting at 42 C in addition to
a
polyethylene fraction which melts at 122 to 124 C. The modulii and tensile
strength of
the polymers for runs 2A and 2B are shown in Table 3.
EmMle 3
A polymerization was carried out by the procedure in Example 1 using the
reaction conditions as shown in Table 4(samples 3A and 3B). The diene, ENB,
was
added to the main reactor feed to produce a polymer containing ENB in the PE
block.
Ethylene and propylene feeds were added to the reactor at residence times of
0.024 and
0.066 min. ENB feed rates were 2.8 and 1.7 g/hr. and the corresponding
polymers
contained 0.333 and 0.14 weight percent ENB. These polymers when coupled are
useful
as lubricating oil viscosity modifiers.
EaMle 4
In this example, a number of A B block polymers made by the procedure in
Example 1 but over a broad range of reaction conditions, are tested for
solubility in
hexane at 22 C. The purpose of this testing is to determine how much B block
is
unconnected to an A block. The composition and molecular weight of the
polymers vary
widely. Solubility is determined by pressing 2.0 g of the block polymer onto a
20 mesh
screen and immersing the polymer and screen in 200 cc of n-hexane. Wide-
mouthed
bottles were used and were occasionally swirled over a period of 3 to 5 days.
The
screen is removed and dried to constant weight in a vacuum oven to determine
the
amount of insoluble polymer. The hexane supernatant liquid is evaporated to
dryness
and the residue is weighed to measure the amount of soluble polymer. The sum
of the
two fractions showed 100% of the starting polymer is accounted for.
CA 02187233 2004-11-17
_ 28 _
A control sample of a high density polyethylene which was melt blended with
EPDM in a BrabenderImixing head at 180 C was also extracted in the same
manner.
These results are presented in Table 5. In the control blend, all 40% of the
EPDM was
extractable, showing that the rubber is soluble, even at high PE block
content, if it is not
attached to a PE block. An infrared analysis showed the soluble material to be
over 98%
EPDM. PE is not extracted. All of the block polymers of Table 5 show soluble
rubber
of less than 25%.
Examnle 5 rophetic Example)
In this example analyses for PE block content and yield of A B block polymer
as
a percentage of the total product is described. Three A B block copolymers
with a diene
containing segment in the A block, are produced by the procedure described in
Example
1. Nearly 100% of the ethylene has reacted by the time that the first
ethylene/propylene
side stream feed is added to make the elastomeric B block. Thus, the weight
percent of
A block in a polymer can be estimated by dividing the ethylene feed rate in
the main flow
to the reactor inlet by the total polymerization rate. We can also estimate
the amount of
A block by dividing the heat of fusion measured by DSC over the melting range
of 80 C
to 135 C, by the heat of fusion measured by DSC for a pure polyethylene A
block of
approximately the same molecular weight, as shown in Figure 3, made by adding
only an
ethylene feed to the reactor. A value of 181 J/g. is used for the heat of
fusion of
polyethylene based on averaging the results from a number of samples.
The polymer samples are fractionated in a Kumagawa apparatus. In this
apparatus an individual sample is sequentially extracted with a series of
solvents of
increasing boiling point. For each solvent continuous extraction is carried
out until all
soluble polymer is dissolved. The solvents used and their boiling points (bp)
were: n-
hexane (bp=69 C), cyclohexane (bp=81 C), n-heptane (bp= 98 C), and toluene
(bp=
111 C). The polymer soluble in each solvent is recovered, weighed, and
analyzed by
DSC. By determining the amount of polymer soluble in each solvent and the
amount and
percentage of PE block in that soluble portion, the percentage of the portion
that was
non-crystalline EP block can be calculated.
Although the present invention has been described in considerable detail with
reference
to certain preferred versions thereof, other versions are possible. Therefore,
the spirit
and scope of the appended claims should not be limited to the description of
the
WO 95/27746 PCTIUS95/04250
2l~ ~2
- 29 -
preferred versions contained herein.
TABLE 1
EXAMPLE IA I B 2A 2B
MAIN FLOW g/h
hexane 53803 53803 5380:3 53803
:L O propylene 0 0 0 0
ethylene 151 124 151 73
ENB 0 0 0 0
VC14 1.8 1.5 2.4 2.4
Al/V mol/mol 8 8 8 8
1.5 SIDE STREAM 1, g/h
hexane 8910 8910 8910 8910
propylene 1228 1354 1125 1125
ethylene 110 148 122 122
SIDE STREAM 2, g/h
2 0 hexane 6138 6138 5910 5910
propylene 358 509 413 413
ethylene 85 110 130 130
SIDE STREAM 3, g/hr
hexane 6217 6217 7920 7920
2 5 propylene 347 405 510 510
ethylene 80 108 255 255
TEMPERATURE, C
feed 20 20 19 19
reactor outlet 22 22 25 24
30 RESIDENCE 'ITME, min.
to side stm,am 1 0.024 0.024 0.024 0.024
to side stream 2 0.064 0.064 0.109 0.109
to side streem 3 0.10 0.10 0.147 0.147
to side stream 4
35 Total 0.139 0.139 0.183 0.183
PROCESS RESULTS
wt % C2 in polymer 71.6 70.8 72.2 70.1
wt % ENB in polymer 0 0 0 0
Mooney(1+4, 150 C) 109 91.1 114 131
40 Mw x 10-3 189 246 222 209
Mn x 10-3 108 149 115 106
Mw/Mn 1.67 1.7 1.91 1.99
Poly Rate, g/h 387 368 689 597
C2=conv % 65 54.8 75.6 72.2
45 C3=conv =, % 5.7 4.4 9.4 8.7
Cat efl;g poly/g VC14 215 245.3 297 249
' conv = conversion
WO 95/27746 PCT/US95/04250
30 -
TABLE 2
. .;:: ::. ,: .::::. .=.:
. .... . . = . .., ..::.,=..,~,=: =.,:::; ::.>F<::.:~., ., .. . . . :;.,.. .
~~
; ' ~;=< ~.. :. .,= = :<c =:. .. : ::<.
,:.,=: =:.,, ,. r:." , ;.,,:,.;.',+.: ii;.=,'''~.,i,.i,d:<'' ;%:=::
Poly rate A block, g/hr 151 124 151 73
Poly rate B block, glhr 236 244 319 355
Poly rate C block, g/hr 0 0 259 265
A block, wt % 39.0 33.7 20.7 10.5
B block, wt % 61.0 66.3 43.7 51.2
C block, wt % 0 0 35.5 38.2
wt % C2= in whole 1 er 71.6 72.9 72.2 70.1
wt % C2= in B block before final 53.4 59.1 59.0 63.9
feed
wt % C2= in B block after fuwi feed 72.2 70.1
wt % ENB whole polymer
wt % ENB in EPDM ent
~"~rPC::><? :::' :
Mw x 10-3 189 246 221 209
Mn x 10-3 108 149 115 106
Mw/Mn 1.67 : .7 1.91 1.99
A block, J/g 48 33 29.2 21.3
B block, J/ 0.82 3.59 4.14
Wt. % soluble in n-hexane 2.3 2.6
TABLE 3
:; .:...:....:::::::::.::.., :.; . ,.,, . .,:=::<..::.::>L.::~::.:~:.:<:
:................ .
,:.. . :. :::::.......... .y:
. . , : ::::. = .
=: ,.,.~.:..; =tS.::.',.i5;.'= ': i~f
..=~. ~ ~=7,.:~: ...::=::=::.; =: ~';:::~:~:::;<::; :
..:~7~~i?+:::: ;?f:.'=:~:[ki~'i;;ii '?~~:~a7i:':'i'ii
100% MODULUS, MPa 2.4 2.3 2.7 2.2
TENSII.E STRENGTH AT BREAK, 3.5 9.7 15.4 5.4
MPA
EXTENSION AT BREAK, % 780 1220 1090 740
WO 95/27746 2 8 7 23~ PCT/US95/04250
~.
- 31 -
TABLE 4 (Example 3)
. . : . . .. :.....:::... . . .: .:.: ,. ..; .. . .
' ~~ . '~
=.~
.... ......:..~...:=::....{i::: '
. .. : ::: . ..~ .: :..::::... ..
:'' . =. :.:. ~ a ......;.:...
N<=:
v . .. .:. ...... . . .: . ...::................... ......................
.............
hexane 53605 53526
propylene 0 0
ethylene 253 253
diene 2.8 1.71
catalyst 3.36 3.36
AIN, mol/mol 7
........
~14~~"~'REJRIM:.~ . ;::,:.:.<.;::<.:::>:.:= .:.:..::.::.::<:>::;>:;:;: ::>::;
hexane 6692 6692
propylene 1234 1234
111 111
ethylene
hexane 9900 9900
propylene 468 471
ethylene 112 112
hexane
propylene
ethylene
ENB
,.......
E~l: ::. S :;::>:
..... .................... ..
Reactor feed, C 20 20
Reactor outlet, C 31 31
a~3~kEt~CE TtM mEn
to side stream 1 0.024 0.024
to side stream 2 0.066 0.066
to side stream 3
Total 0.142 0.142
_ ...:..
PR~JC0S REgULTS
..::.. .
Wt. % C2=in polymer 73.2 71.5
Wt. % ENB in polymer 0.33 0.14
Mooney 1+ 4, 150 C 51 49.8
A Block, % of polymer
Poly Rate, g/h 592.5 604
C2= aonv, % * 90.8 90.6
C3= conv, % * 9.3 10.1
ENB conv, % * 69.8 49.5
Cat eff, I/ VCI 176.4 179.8
*conv = conversion
WO 95/27746 PCTIUS95/04250
32 _,
TABLE 5
Run Wt. % C2= Mn x 10-3 Mw x 10-3 Hexane soluble,
in Pol . %
317a 68 75 139 12.1
317b 68 ~ 97 193 13.0
317c 71 118 228 4.9
317d 69 92 189 12.5
318a 63 69 118 22.1
318b 62 62 118 23.5
318c 64 88 208 16.6
318d 66 92 179 16.9
319a 66 108 160 13.2
319c 68 108 230 7.8
320a 71 108 206 4.1
320c 70 128 237 3.3
323a 72 137 289 2.9
323b "71~y_~_ 152 307 2.2
332a 68 149 258 11.3
333a 68~~~ 104 212 7.7
334a 69 126 :195 4.9
334b 67117 178 8.0
335a 66 M~ 94 343 10.1
335b 70 - 6.5
336a 69 15.2
336d 6f, ~ 19.0
336e 69 74 147 3.7
338b - - 6.0
60% HDPE/ 39.6
40% EPDM
40 !o HDPE/ 610
60% EPDM
