Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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LOW CRYSTALLINE POLYMER COMPOSITIONS
PREPARED IN A DUAL REACTOR
INVENTORS: Danny Van Hoyweghen, Cynthia A. Mitchell, Achiel J.M. Van Loon,
Narayanaswami Dharmarajan, Sudhin Datta
FIELD OF THE INVENTION
[0002] This
application relates to polymer compositions and processes for making thereof,
prepared in a dual reactor.
to BACKGROUND OF THE INVENTION
[0003] The present
invention relates to low crystalline polymer compositions and
processes for making compositions. Polymer compositions having a desirable
balance of
properties and attributes, leading to enhanced compositions that are useful in
a number of
applications, are generally sought. Such composition enhancements can manifest
themselves
.. in a variety of ways depending on the specific application and the specific
blend contemplated.
Such enhancements include, but are not limited to: (1) processibility in the
molten state in such
processes as milling, extrusion, calendering and injection molding; (2)
initial physical
properties in a solid state such as toughness, tack, adhesion, tear
resistance, toughness, sealing,
tensile and elongation; (3) improvements in the above-mentioned properties;
and (4) long-term
zo maintenance of such physical properties. A variety of approaches have
been suggested to obtain
polymer compositions with the desired properties and attributes, but those
approaches have
experienced various shortcomings.
[0004] U.S. Patent
No. 5,747,592 discloses a thermoplastic composition with
polypropylene, rubber, and a plastomer. U.S. Patent No. 8,618,033 discloses an
ethylene
.. copolymer with 40-70 wt% of units derived from ethylene and at least 30 wt%
of units derived
from at least one a-olefin having 3 to 20 carbons. U.S. Patent No. 7,585,917
discloses a process
for making thermoplastic blend compositions having a physical blend of a first
polymer
component, having polypropylene, and a second polymer component, having a
reactor blend
of a propylene polymer and an ethylene a-olefin elastomer.
[0005] U.S. Patent No. 6,207,756 discloses a polymer dispersion having a
substantially
amorphous elastomer and a semicrystalline plastic, prepared via a dual reactor
in series (i.e.,
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the individual components of the elastomer and semicrystalline are made in
separate
reactors). U.S. Patent No. 6,319,998 also discloses a polymer blend made by a
series reactor
process. However, a series reactor process does not allow for much variability
in the
components produced in each of the reactors. In addition, series reactor
process requires the
.. use of a single catalyst.
[0006] Accordingly, there is a need for a dual reactor polymer
composition, prepared by a
flexible parallel process that provides suitable properties for film
applications, including tear
resistance and toughness, as compared to compositions currently available.
SUMMARY OF THE INVENTION
[0007] As described more fully below, the inventors have discovered that a
blend
composition with a propylene polymer and an ethylene a-olefin elastomer, where
the
composition has a low melt index, is suitable for use in film applications as
a compatibilizer,
where properties such as tear resistance and film toughness are sought.
[0008] Provided herein is a polymer blend composition comprising from
about 65 wt% to
.. about 90 wt% based on the total weight of the blend of an ethylene a-olefin
elastomer having
either no crystallinity or crystallinity derived from ethylene, having about
70 wt% or more
units derived from ethylene; and from about 10 wt% to about 35 wt% based on
the total
weight of the blend of a propylene polymer having about 40 wt% or more units
derived from
propylene, including isotactically arranged propylene derived sequences;
wherein the
ethylene a-olefin elastomer and the propylene polymer are prepared in separate
reactors
arranged in parallel configuration.
DETAILED DESCRIPTION OF THE INVENTION
[0009] Various specific embodiments and versions of the present invention
will now be
described, including preferred embodiments and definitions that are adopted
herein. While
the following detailed description gives specific preferred embodiments, those
skilled in the
art will appreciate that these embodiments are exemplary only, and that the
present invention
can be practiced in other ways. Any reference to the "invention" may refer to
one or more,
but not necessarily all, of the embodiments defined by the claims. The use of
headings is for
purposes of convenience only and does not limit the scope of the present
invention.
[0010] All numerical values within the detailed description and the claims
herein are
modified by "about" or "approximately" the indicated value, and take into
account
experimental error and variations that would be expected by a person having
ordinary skill in
the art.
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[0011] Various terms as used herein are defined below. To the extent a
term used in a
claim is not defined below, it should be given the broadest definition persons
in the pertinent
art have given that term as reflected in at least one printed publication
(e.g., a dictionary or
article), issued patent or published application.
[0012] Continuous. When used to describe a process or an aspect of a
process, e.g., a
process step, the term "continuous" and its derivatives, including
"continuously," shall cover
any process or step in which reagents and reacted products are supplied and
removed
continuously so that steady state, stable reaction conditions can be achieved.
[0013] Polymer. Except as required by the particular context, the term -
polymer" used
to .. herein is the product produced by particular continuous polymerization
in a particular
polymerization zone or reactor.
[0014] Polymerization. As used herein, the term "polymerization" to be
given the
broadest meaning used by persons skilled in the art refers to the conversion
of monomer into
polymer. Polymerization zone refers to the zone in which polymerization takes
place and is
generally formed by a back mixed reactor for forming a substantially random
polymer.
[0015] Polysplit. As used herein, the term "polyspliC shall mean the
calculated result of
the weight of the first polymer (ethylene polymer) that is produced from the
first
polymerization zone divided by the combined weight of the first polymer and
the second
polymer (propylene polymer). The same definition applies equally to series and
parallel
reactor configurations. That is, the ethylene polymer is always regarded as
the numerator.
[0016] Melting Point, Heat of Fusion and Crystallization. The polymers
and compositions
described herein can be characterized in terms of their melting points (Tm)
and heats of
fusion, which properties can be influenced by the presence of comonomers or
steric
impurities that hinder the formation of crystallites by the polymer chains.
Measurements were
performed on a Pyris 1 Differential Scanning Calorimeter. Samples may be
tested in the
form of powders, granules, pellet, film, sheet and molded specimens. Sample
weight for
measurement is 5 +/- 0.5 mg. Materials were tested from -20 C to 18 0C at 10
C/min rates.
Melting temperature and heat of fusion are taken from the 2nd Melt. The
thermal output is
recorded as the area under the melting peak of the sample and is measured in
Joules as a
measure of the heat of fusion. The melting point is recorded as the
temperature of the greatest
heat absorption within the range of melting of the sample.
[0017] Comonomer Content. The comonomer content of the polymer is
measured using
13C nuclear magnetic resonance (NMR). The 13C solution NMR was performed on a
lOmm
broadband probe at a field of at least 600MHz in tetrachloroethane-d2 solvent
at 120 C with
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a flip angle of 90 and full NOE with decoupling. Sample preparation (polymer
dissolution)
was performed at 140 C where 0.20 grams of polymer was dissolved in an
appropriate
amount of solvent to give a final polymer solution volume of 3mL. Chemical
shifts were
referenced by setting the most intense propylene methyl group signal to 21.83
ppm. The
composition calculations of the ethylene propylene copolymer are described by
Randall in -A
Review Of High Resolution Liquid 13Carbon Nuclear Magnetic Resonance
Characterization
of Ethylene-Based Polymers", Polymer Reviews, 29:2, pp. 201-317 (1989).
[0018]
Molecular Weight Characteristics. Mw, Mn and Mw/Mn are determined by using
a High Temperature Gel Permeation Chromatography (Agilent PL-220), equipped
with three
io in-line detectors, a differential refractive index detector (DRI), a
light scattering (LS)
detector, and a viscometer. Experimental details, including detector
calibration, are described
in: T. Sun, P. Brant, R. R. Chance, and W. W. Graessley, Macromolecules,
Volume 34,
Number 19, pp. 6812-6820, (2001) and references therein. Three Agilent PLgel
10um
Mixed-B LS columns are used. The nominal flow rate is 0.5 mL/min, and the
nominal
injection volume is 300 L. The various transfer lines, columns, viscometer
and differential
refractometer (the DRI detector) are contained in an oven maintained at 145 C.
Solvent for
the experiment is prepared by dissolving 6 grams of butylated hydroxytoluene
as an
antioxidant in 4 liters of Aldrich reagent grade 1,2,4-trichlorobenzene (TCB).
The TCB
mixture is then filtered through a 0.1 um Teflon filter. The TCB is then
degassed with an
online degasser before entering the GPC-3D. Polymer solutions are prepared by
placing dry
polymer in a glass container, adding the desired amount of TCB, then heating
the mixture at
160 C with continuous shaking for about 2 hours. All
quantities are measured
gravimetrically. The TCB
densities used to express the polymer concentration in
mass/volume units are 1.463 g/m1 at room temperature and 1.284 giml at 145 C.
The
.. injection concentration is from 0.5 to 2.0 mg/ml, with lower concentrations
being used for
higher molecular weight samples. Prior to running each sample the DRI detector
and the
viscometer are purged. Flow rate in the apparatus is then increased to 0.5
ml/minute, and the
DRI is allowed to stabilize for 8 hours before injecting the first sample. The
LS laser is
turned on at least 1 to 1.5 hours before running the samples. The
concentration, c, at each
point in the chromatogram is calculated from the baseline-subtracted DRI
signal, 'DRI' using
the following equation:
c KDRIIDRI/On/610
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where KDRI is a constant determined by calibrating the DRI, and (dn/dc) is the
refractive
index increment for the system. The refractive index, n = 1.500 for TCB at 145
C and A=
690 nm. Units on parameters throughout this description of the GPC-3D method
are such
that concentration is expressed in g/cm3, molecular weight is expressed in
g/mole, and
intrinsic viscosity is expressed in dL/g.
[0019] The LS detector is a Wyatt Technology High Temperature DAWN HELEOS.
The molecular weight, M, at each point in the chromatogram is determined by
analyzing the
LS output using the Zimm model for static light scattering (M.B. Huglin, LIGHT
SCATTERING
FROM POLYMER SOLUTIONS, Academic Press, 1971):
c Ko
1õ + 2A 2 C .
AR(0) MP(0)
Here, AR(0) is the measured excess Rayleigh scattering intensity at scattering
angle 0, c is the
polymer concentration determined from the DRI analysis, A2 is the second
virial coefficient.
P(0) is the form factor for a monodisperse random coil, and Ko is the optical
constant for the
system:
K = 47c2n2(dn/dc)2
4 xT
,1 A
where NA is Avogadro's number, and (dn/dc) is the refractive index increment
for the
system, which take the same value as the one obtained from DR1 method. The
refractive
index, n = 1.500 for TCB at 145 C and X = 657 nm.
[0020] A high temperature Viscotek Corporation viscometer, which has four
capillaries
arranged in a Wheatstone bridge configuration with two pressure transducers,
is used to
determine specific viscosity. One transducer measures the total pressure drop
across the
detector, and the other, positioned between the two sides of the bridge,
measures a
differential pressure. The specific viscosity, is, for the solution flowing
through the
viscometer is calculated from their outputs. The intrinsic viscosity, [i], at
each point in the
chromatogram is calculated from the following equation:
= chi 0.3(402
where c is concentration and was determined from the DRI output.
[0021] The branching index (givis) is calculated using the output of the
GPC-DRI-LS-VIS
method as follows. The average intrinsic viscosity, Havg, of the sample is
calculated by:
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Ec,
rniavg Ec.
where the summations are over the chromatographic slices, i, between the
integration limits.
The branching index g'vl, is defined as:
g vis = [Tlim
kW:
M, is the viscosity-average molecular weight based on molecular weights
determined by LS
analysis. Z average branching index (g'za,e) is calculated using Ci = polymer
concentration in
the slice i in the polymer peak times the mass of the slice squared, MP.
[0022] All
molecular weights are weight average unless otherwise noted. All molecular
weights are reported in g/mol unless otherwise noted.
[0023] Mooney Viscosity. The term "Mooney Viscosity" a term used to
characterize
certain polymers, polymer components, and polymer compositions herein. As used
herein, the
term Mooney Viscosity (ML (1+4) at 125 C) or simply "Mooney Viscosity," to be
defined and
measured according to the definition and measurement procedure set forth in
U.S. Patent No.
6,686,415. Alternatively, any "Mooney Viscosity" value referenced herein
(including those in
the claims) is deemed to encompass any Mooney Viscosity measured in accordance
with any
recognized, published procedure for measuring Mooney Viscosity.
[0024] MI. The
term "MI" used herein stands for "Melt Index". The units for "MI" are
grams per 10 minutes and the test to be herein for determining MFR/MI is set
forth in any
version and condition set forth in ASTM-1238 that uses 2.16 kg at 190 C.
[0025] One or more of the compositions described herein, the ethylene
polymer is present
in the composition in an amount of more than 65 wt% based on the total weight
of the polymer
composition.
[0026] One or more
of the compositions described herein, further comprises a filler, or a
plasticizer, or both.
[0027] In one or more of the compositions described herein, the polymer
composition is
substantially free from diene units.
[0028] In one or
more of the compositions described herein, the ethylene polymer is a low
crystalline ethylene propylene copolymer.
[0029] In one or
more of the compositions described herein, the blend is a reactor blend
formed in a parallel process.
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Blends
[0030] One of the components or elements in certain compositions is a
blend. Preferably,
the composition is a reactor blend. The reactor blends include at least a
first polymer
(ethylene polymer) and a second polymer (propylene polymer), as discussed
below. The term
"reactor blend" to be given the broadest meaning and/or scope that persons
skilled in the art
have given that term, as reflected in how the term has been used in at least
one patent or
printed publication.
[0031] Nevertheless, a "reactor blend" herein distinguished from a
"physical blend", the
to latter being the combination of two or more polymers that have already
been formed and
recovered before being mixed or otherwise combined, e.g., separated (which
would
preferably also include being devolatilized) from some or all of the remaining
polymerization
mixture (e.g., unreacted monomers and/or solvent) and then combined together.
[0032] The term "reactor blend" does not preclude (except to the extent
stated otherwise)
two components that have reacted to some extent or degree with one another,
e.g., where one
is a reaction product that is derived from the other, in whole or in part. Nor
does the term
"reactor blend" preclude two components that are mixed together but that can
be separated by
conventional means (e.g., fractionation) following formation and therefore can
be identified
as distinct polymers, e.g., a semicrystalline polymer having a distinct
melting point (Tm) and
an atactic or amorphous ethylene elastomer having either a low melting point
(Tm) or no
melting point.
[0033] The term "reactor blend" used herein may in certain embodiments
refer to a
homogenous (e.g., a single phase) material while in other embodiments it may
refer to a
multiphase blend (e.g., two or more distinct phases). A blend formed by melt-
blending or
dry-blending is a physical blend.
[0034] The reactor blend compositions preferably include at least a
propylene polymer
and an ethylene polymer, although the ethylene polymer is in some cases
identifiable by
inference and/or by fractionation. In certain embodiments, the reactor blend
includes a major
portion by weight (more than 65 wt%) ethylene polymer with a minor portion
(less than 35
wt%) propylene polymer.
[0035] In certain embodiments of the reactor blend, the first polymer and
second polymer
form a substantially homogenous reactor blend, meaning that the first polymer
and second
polymer are part of, or are within, or occupy, the same phase. In other
embodiments of the
reactor blend, the first polymer and second polymer form distinct phases of a
multiphase
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composition. In certain multiphase embodiments, a reactor blend includes a
continuous phase
(either the first polymer or the second polymer), which may be a dispersed
phase (dispersion)
and a discontinuous phase (either the first polymer or the second polymer),
which may be a
matrix phase. In those embodiments, either the continuous phase or the
dispersed phase may
represent a major portion of the reactor blend. Also, at least one embodiment
of the reactor
blend is a multiphase composition having a continuous phase that includes
first polymer as a
minor portion of the reactor blend and a dispersed phase that includes second
polymer as a
major portion. Further, in any of the above embodiments, the second polymer
can be
crosslinked. The various polysplit ranges identified above may be used.
Multistage Polymerization
[0036] The blends described herein are formed in either batch or
continuous "multistage
polymerization," meaning that two (or more) different polymerizations (or
polymerization
stages) are conducted. More specifically, a multistage polymerization may
involve either two
or more sequential polymerizations (also referred to herein as a "series
process" two or more
parallel polymerizations (also referred to herein as a "parallel process").
Preferably, the
polymerization is conducted in a parallel process.
[0037] The polymers made in the respective reactors of the continuous,
multiple reactor
solution plant are blended when in solution without prior isolation from the
solvent. The
blends may be the result of series reactor operation, where the effluent of a
first reactor enters
a second reactor and where the effluent of the second reactor can be submitted
to finishing
steps involving devolatilization. The blend may also be the result of parallel
reactor operation
where the effluents of both reactors are combined and submitted to finishing
steps. Either
option provides an intimate admixture of the polymers in the devolatilized
blend. Either case
permits a wide variety of polysplits to be prepared whereby the proportion of
the amounts of
polymers produced in the respective reactors can be varied widely.
[0038] The first polymer and second polymer making up the blend
composition are
discussed below, followed by a section on the parallel process.
Ethylene Polymer
[0039] The blends described herein include a first polymer component
(first polymer),
which preferably is (or includes) an elastomer that is predominantly ethylene,
i.e., having
more than 30 wt% or 40 wt%, or 50 wt% units derived from ethylene monomer. The
crystallinity, and hence other properties as well, of the first polymer are
preferably different
from those of the second polymer.
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[0040] The polymers described herein are predominantly ethylene, i.e.,
having more than
70 wt% units derived from ethylene monomer. In one or more of the compositions
described
herein, the ethylene content of the ethylene polymer is greater than or equal
to about 65 wt%,
preferably greater than about 70 wt%, or 75 wt% to less than about 85 wt% or
about 90 wt%.
In an embodiment, the ethylene polymer has a propylene content of less than
about 30 wt%,
preferably 25%, or 23 wt% to greater than about 15 wt% or about 10 wt%. In an
embodiment,
the ethylene polymer has a C4-C20 a-olefin content of less than about 5 wt%.
Preferably, the
first polymer (also referred to as the "ethylene polymer") has some
crystalline (including
"semi-crystalline"), also referred to herein as "crystallinity derived from
ethylene." But any
io crystallinity of the first polymer is preferably derived from the
ethylene. The percent
crystallinity in such cases is measured as a percentage of polyethylene
crystallinity and thus
the origin of the crystallinity from ethylene is established.
[0041] Preferably, in addition to units derived from ethylene, the first
polymer also
includes units derived from an a-olefin monomer. Suitable a-olefin monomers
include, but
are not limited to propylene, butene, pentene, hexene, heptene, or octene, and
their isomers.
Advantageously, the first polymer can be formulated using different cc-olefin
monomers,
selected from the list above, and/or different amounts of monomers, e.g.,
ethylene and a-
olefin monomers, to prepare different types of polymers, e.g., ethylene
polymers having
desired properties.
[0042] Preferably, the first polymer is formed during (or by) the first
polymerization,
which in the case of a parallel process, involving parallel polymerization
and/or parallel
reactors, the "first polymer" may be formed at the same time as the "second
polymer," but the
product streams (still including solvent) are combined after the first and
second polymers are
sufficiently formed.
[0043] One purpose of the first polymer is to enhance the attributes of the
second
polymer. Such enhancements can manifest themselves in a variety of ways
depending on the
specific application and the specific blend contemplated. Such enhancements
include, but are
not limited to, improvements in cure rate and state; processability as defined
by such
processes as milling, extrusion, calendering and injection molding; physical
properties such
as toughness, tack, adhesion, tear resistance, tensile and elongation and heat
aging as defined
by the retention of such physical properties at elevated temperatures. In
addition, the
inclusion of a reactor blend of two polymers (the first ethylene-based and the
second
propylene-based) improves the compatibility properties of resultant blend,
when used as in a
film layer between an ethylene-based film layer and a propylene-based film
layer.
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Propylene Polymer
[0044] As noted above, the blends herein preferably include at least a
propylene polymer,
which is preferably the polymer formed by a second polymerization reaction
(under
conditions described elsewhere herein) and preferably in a "second reactor"
part of a parallel
process.
[0045] The propylene polymer should have (at minimum) 40 wt% propylene
units, and
preferably more, as noted below. The propylene polymer is preferably a
polypropylene
copolymer having 60 wt% or more units derived from propylene, having
isotactically
arranged propylene derived sequences and having a heat of fusion less than 45
J/g. Also, the
io polypropylene copolymer preferably has at least 5 wt% non-propylene
comonomer units,
e.g., ethylene units, and more preferably at least 10 wt% or more ethylene
units.
[0046] The propylene polymer preferably comprises >60 wt%, more preferably
>75 wt%
propylene-derived units. In some embodiments, the propylene polymer comprises
from 75-95
wt% of propylene-derived units, more preferably from 80-90 wt% of propylene-
derived units,
is the balance comprising one or more a-olefins. Other suitable embodiments
include propylene
derived units in an amount (based on the weight of propylene and a-olefin)
ranging from
about 75-93 wt%, more preferably about 75-92.5 wt%, more preferably about 75-
92 wt%,
more preferably 75-92.5 wt%, more preferably 82.5-92.5 wt%, and more
preferably about
82.5-92 wt%. Corresponding. a-olefin ranges include 5-25 wt%, more preferably
7-25 Wici/O,
20 more preferably 7.5-25 wt%, more preferably 7.5-17.5 w% and more
preferably 8-17.5 wt%
(based on the weight of propylene and a-olefin). A preferred a-olefin is
ethylene. The
propylene polymer preferably has a MFR < about 800, more preferably < about
500, more
preferably < about 200, more preferably < about 100, more preferably < about
50.
Particularly preferred embodiments include a propylene polymer with an MFR of
from about
25 1-25, more preferably about 1-20. The crystallinity of the first polymer
should be derived
from isotactic polypropylene sequences. The isotacticity of the propylene
polymer can be
illustrated by the presence of a preponderance of the propylene residues in
the polymer in
mm triads. As noted elsewhere herein, the tacticity of the propylene polymer
is preferably
greater than the tacticity of either the reactor blend or the ethylene
polymer, e.g., where the
30 propylene polymer is isotactic and the ethylene polymer is atactic.
[0047] The crystallinity of the propylene polymer can be expressed in
terms of heat of
fusion. The propylene polymer of the invention can have a heat of fusion, as
determined by
DSC, ranging from a lower limit of 1 J/g, or 1.5 J/g, or 3 J/g, or 4 J/g, or 6
J/g, or 7 J/g or 10,
to an upper limit of 20 or 30 J/g, or 40 J/g, or 50 J/g, or 60 J/g, or 75 J/g.
Preferably, the heat
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of fusion of the propylene polymer is less than 45 J/g. Without wishing to be
bound by
theory, it is believed that the propylene polymer has generally isotactic
crystallizable
propylene sequences, and the above heats of fusion are believed to be due to
the melting of
these crystalline segments.
[0048] The level of crystallinity of the propylene polymer can also be
reflected in its
melting point. Preferably, the propylene polymer has a single melting point.
However, a
sample of propylene copolymer will often show secondary melting peaks adjacent
to the
principal peak. The highest peak is considered the melting point. The
propylene polymer
described herein can have a melting point by DSC within the range having an
upper limit of
to 115 C, or 110 C, or 105 C, or 90 C, or 80 C, or 70 C, and a lower limit
of 0 C, or 20 C, or
25 C, or 30 C, or 35 C, or 40 C, or 45 C. Preferably, the propylene polymer
has a melting
point of less than 105 C, and more preferably less than 100 C, and even more
preferably less
than 90 C. Also, it is preferred that the propylene polymer have a melting
point greater than
about 25 C, or 40 C.
[0049] For the propylene polymer, at least 75% by weight of the polymer, or
at least 80%
by weight, or at least 85% by weight, or at least 90% by weight, or at least
95% by weight, or
at least 97% by weight, or at least 99% by weight of the polymer is soluble in
a single
temperature fraction, or in two adjacent temperature fractions, with the
balance of the
polymer in immediately preceding or succeeding temperature fractions. These
percentages
are fractions, for instance in hexane, beginning at 23 C and the subsequent
fractions are in
approximately 8 C increments above 23 C. Meeting such a fractionation
requirement means
that a polymer has statistically insignificant intermolecular differences of
tacticity of the
polymerized propylene.
[0050] In certain embodiments, the percentage of mm triads in the
propylene polymer, as
determined by the method for determining triad tacticity, is in the range
having an upper limit
of 98%, or 95%, or 90%, or 85%, or 82%, or 80%, or 75%, and a lower limit of
50%, or 60%.
[0051] Certain propylene polymers have an isotacticity index greater than
0%, or within
the range having an upper limit of 50%, or 25% and a lower limit of 3%, or
10%.
[0052] Certain propylene polymers can have a tacticity index (m/r) within
the range
having an upper limit of 800, or 1000, or 1200, and those polymers may have a
lower limit of
40, or 60.
[0053] The second polymerization may in certain cases be conducted in the
presence of
an a-olefin; thus the resulting polymer formed when such a-olefin is present
will include
"units derived" from such a-olefin. Either the same a-olefin or different a-
olefins can be
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introduced to the first and second polymerizations. Particular examples of
those a-olefins are
C3-C20 a-olefins, including, but not limited to, propylene; butene-1; pentene-
1,2-
methy 1pentene-1,3 -methy lb utene-1 ; hexene-
1,3 -methy 1pentene-1,4-methy 1pentene-1,3,3-
di methyl buten e-1; heptene-1; hexene-1;
methylhexene-1; di methylpentene-1
trimethylbutene-1; ethylpentene-1; octene-1; methylpentene-1; dimethylhexene-
1;
trimethylpentene-1; ethylhexene-1; methvlethy 1pentene-1; diethylbutene-1;
propylpentane-1;
decene-1; methylnonene-1; nonene-1; dimethyloctene-1; trimethylheptene-1;
ethyloctene-1;
methyl ethylbutene-1; diethylhexene-1; dodecene-I and hexadodecene-1.
Parallel Polymerization Process
io [0054] The
following methods can be followed in the production of blends of propylene
polymers and ethylene polymers where each component of the blend (e.g., the
propylene
polymer and the ethylene polymer) contains a different ratio of ethylene to
propylene.
[0055]
Preferably, the composition is a reactor blend. The method discussed below has
the advantage of eliminating the need for a melt blending operation and
enables intimate
is blends of the copolymers to be made in the original reaction medium.
Such materials have
unique properties because they are not subjected to shear degradation in melt
processing
equipment. The degree of dispersion of each component of the blend is more
intimate.
[0056]
Disclosed herein are continuous processes for making an elastomeric
composition
that comprises an ethylene polymer and a propylene polymer, the process
comprising:
20 polymerizing in a first polymerization zone in a solvent a combined feed
of a first monomer
system and a first catalyst system to provide a mixture that includes the
ethylene polymer,
said ethylene polymer preferably being a random copolymer of ethylene and
propylene
derived units, wherein the ethylene polymer is either noncrystalline or has
ethylene-type
crystallinity; polymerizing in a second polymerization zone in a solvent a
feed of a second
25 monomer system and a second catalyst system capable of providing
isotactic stereoregularity
to sequences of propylene derived units to provide a mixture of the propylene
polymer and
unreacted monomers, said propylene polymer preferably having 60 wt% or more
units
derived from propylene, including isotactically arranged propylene derived
sequences and
further having a heat of fusion less than 45 J/g or a melting point less than
105 C or both and
30 a Mooney Viscosity (ML (1+4) at 125 C) of from 1 to 45; and combining in
the presence of
the solvent the propylene polymer and the ethylene polymer wherein the
combination of the
propylene polymer and the ethylene polymer has a Mooney (ML 1+4 at 125 C) of
from 25 to
180, preferably 25 to 40, and a heat of fusion less than 50 J/g.
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[0057] In one example of a parallel process, two reactors are configured
such that
monomers, catalyst(s) and solvent are fed independently to each reactor. The
first and second
polymerizations are preferably taking place simultaneously in a parallel
process.
[0058] For a particular plant design, the plant productivity is controlled
by the bottleneck
presented by the recycle system. With parallel reactors the residence time of
each reactor can
be chosen independently as long as the total solvent flow does not exceed the
recycle
capacity.
[0059] Effluent Streams. As discussed elsewhere herein, during operation
of the
continuous process, each reactor experiences polymerization that produces an
effluent stream.
to That effluent stream can be composed of polymer produced from the
polymerization as well
as catalyst and any unreacted monomers. Each effluent stream can be
characterized as having
a particular polymer concentration. As an example, the polymer concentration
in the effluent
of each reactor can be maintained in the range of 1 to 30% by weight or
between 3 to 20% by
weight, based on the total weight of the particular effluent. In parallel
reactors, there can be
is three effluent streams, i.e., one from each reactor and the combined
effluent stream. The
polymer concentration of the effluent from each of the two reactors preferably
represents the
polymer made in that reactor alone (which can be measured, for example, by
separating the
formed polymer from non-polymer materials). Polymer concentration of the
combined
effluent represents all the polymer material present in the two reactors,
measured at a given
20 time, e.g., after a particular residence time or some other set point.
That polymer material
includes at least the reactor blend, which may include a certain amount of the
propylene
polymer together with at least one other polymer, e.g., an ethylene polymer or
a reaction
product of the other reactants themselves, e.g., the monomers, or both forms
of reactant
product. Although other polymer concentrations or ranges of concentrations may
in certain
25 cases be utilized, it is preferred that the first effluent polymer
concentration range from a low
of 1 wt%, or 2 wt%, or 3 wt%, or 4 wt%, or 5 wt%, or 6 wt%, to a high of 30
wt%, or 25
wt%, or 20 wt%, or 16 wt%, or 12 wt%, or 8 wt%. It is preferred that the
combined effluent
polymer concentration range from a low of 3 wt%, or 4 wt%, or 5 wt%, or 6 wt%,
or 7 wt%,
or 8 wt%, to a high of 30 wt%, or 25 wt%, or 20 wt%, or 18 wt%, or 16 wt%, or
14 wt%.
30 [0060] Polymer Recovery. A polymer can be recovered from the
effluent of either reactor
or the combined effluent, by separating the polymer from other constituents of
the effluent.
Conventional separation means may be employed. For example, polymer can be
recovered
from effluent by coagulation with a nonsolvent such as isopropyl alcohol,
acetone, or n-butyl
alcohol, or the polymer can be recovered by stripping the solvent or other
media with heat or
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steam. One or more conventional additives such as antioxidants can be
incorporated in the
polymer during the recovery procedure. Possible antioxidants include phenyl-
beta-
naphthylamine; di-tert-butylhydroquinone, triphenyl phosphate, heptylated
diphenylamine,
2,2'-methyl ene-bis(4-methyl-6-tert-butyl)phenol, and
2,2,4-tri methy1-6-ph enyl-1,2-
dihydroquinoline. Other methods of recovery such as by the use of lower
critical solution
temperature (LCST) followed by devolatilization are also envisioned.
[0061]
Polymerization Rates. For an adiabatic reactor using feed chilling as the
method
of heat removal, the overall polymerization rate of parallel reactors is set
by the difference
between the temperature of each reactor and the feed temperature. Since
refrigeration is
to limited by the availability of commercial refrigeration units that are
capable of chilling the
feed to about -40 C, the economics is driven by the highest temperature at
which the two
reactors can be operated and still produce the polymer with desired properties
such as
molecular weight and long chain branching. Other factors that influence
polymerization rate
(also called production rate) are solvent type and rate, monomer type and
polymer
composition since the heat of polymerization varies with the choice of
monomer.
[0062]
Molecular Weight. The molecular weight characteristics (e.g., Mw, Mn, etc.) of
the reactor blend and also of the individual-propylene polymer and ethylene
polymer
(polymer components) can in certain circumstances be adjusted depending upon
the desired
properties of the reactor blend. Those molecular weight characteristics are
described
elsewhere herein. For example, the molecular weight characteristics of each
polymer can be
set by choosing the reactor temperature, monomer concentration, and by
optionally adding
chain transfer agents such as hydrogen. Also, molecular weight can generally
be lowered by
increasing reaction temperatures, and raised by increasing monomer
concentrations.
Polymerization Catalysts
[0063] In a broadest form, the compositions can be prepared using any SSC
(single sited
catalyst). Such a catalyst may be a transition metal complex generally
containing a transition
metal Groups 3 to 10 of the Periodic Table; and at least one ancillary ligand
that remains
bonded to the transition metal during polymerization. Preferably, the
transition metal is used
in a reduced cationic state and stabilized by a cocatalyst or activator.
[0064] The ancillary ligand may be a structure capable of forming a it bond
such a
cyclopentadienyl type ring structure. The ancillary ligand may also be a
pyridinyl or amide
ligand. The transition metal is preferably of Group 4 of the Periodic table
such as titanium,
hafnium or zirconium which are used in polymerization in the d mono-valent
cationic state
and have one or two ancillary ligands as described in more detail hereafter.
The important
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features of such catalysts for coordination polymerization are the ligand
capable of
abstraction and that ligand into which the ethylene (olefinic) group can be
inserted.
[0065] The transition metal complex may impose a degree of steric order on
the
propylene monomer by suitable chirality. Where first polymers of higher
molecular weight
are desired or higher polymerization temperatures, it is preferable to a non-
or weakly
coordinated anion (the term non-coordinating anion as used herein includes
weakly
coordinated anions) as cocatalyst. Alternatively, aluminoxanes or complexes
incorporating
oxy-aluminum moieties may be used.
[0066] A precursor for the non-coordinating anion may be used with a
transition metal
to complex supplied in a reduced valency state. The precursor may undergo a
redox reaction.
The precursor may be neutral, such as a borane complex and form the transition
metal cation
by abstracting a ligand from it. The precursor may be an ion pair of which the
precursor
cation, such as a borate, is neutralized and/or eliminated in some manner. The
precursor
cation may be an ammonium salt as in EP 277 003 and EP 277 004. The precursor
cation
may be a triphenyl carbonium derivative as in EP 426 637. The non-coordinating
anion can
be a Group 10-14 complex wherein boron or aluminum is the charge bearing atom
shielded
by ligands which may be halogenated and especially perfuorinated. Preferably,
tetra-aryl-
substituted Group 10-14 non-carbon element-based anion, especially those that
are have
fluorine groups substituted for hydrogen atoms on the aryl groups, or on alkyl
substituents on
those aryl groups.
[0067] The non-coordinating anion may be used in approximately equimolar
amounts
relative to the transition metal complex, such as at least 0.25, preferably
0.5, and especially
0.8 and such as no more than 4, preferably 2 and especially 1.5.
[0068] The transition metal complex may be a pyridine amine complex useful
for olefin
polymerization such as those described in WO 03/040201. The transition metal
complex may
a fluxional complex which undergoes periodic intra-molecular re-arrangement so
as to
provide the desired interruption of stereoregularity as in U.S. Patent No.
6,559,262. The
transition metal complex may be a stereorigid complex with mixed influence on
propylene
insertion, see EP 1070087.
[0069] Preferably, the transition metal complex is a chiral bridged bis
cyclopentadienyl
mD
derivative having the formula LALBLCiE where LA and LB are substituted or
unsubstituted
cyclopentadienyl or hetero-cyclopentadienyl ancillary ligand it-bonded to M in
which the LA
and LB ligands are covalently bridged together through a Group 14 element
linking group; LC;
is an optional neutral, non-oxidizing ligand having a dative bond to M (i
equals 0 to 3); M is a
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Group 4 or 5 transition metal; and, D and E are independently mono-anionic
labile ligands,
each having a c-bond to M, optionally bridged to each other or LA or LB. The
mono-anionic
ligands are displaceable by a suitable activator to permit insertion of a
polymerizable
monomer or macro-monomer can insert for coordination polymerization on the
vacant
coordination site of the transition metal component.
[0070] When using the catalysts, the total catalyst system will generally
additionally
comprise one or more organo-metallic compound as scavenger. Such compounds as
used in
this application is meant to include those compounds effective for removing
polar impurities
from the reaction environment and for increasing catalyst activity.
[0071] In at least one embodiment, a polymerization process consists of or
includes a
polymerization in the presence of a catalyst including a bis(cyclopentadienyl)
metal
compound and either (1) a non-coordinating compatible anion activator, or (2)
an alumoxane
activator. Non-limiting examples of catalyst systems which can be used are
described in U.S.
Patent Nos. 5,198,401 and 5,391,629. In a particular aspect of this
embodiment, an
is alumoxane activator can be used in an amount to provide a molar aluminum
to metallocene
ratio of from 1:1 to 20,000:1. In another particular aspect of this
embodiment, a non-
coordinating compatible anion activator can be used in an amount to provide a
molar ratio of
biscyclopentadienyl metal compound to non-coordinating anion of from 10:1 to
1:1. In yet
another particular aspect of this embodiment, the polymerization reaction is
conducted by
reacting monomers in the presence of a catalyst system described herein at a
temperature of
from 0 C to 200 C for a time of from 1 second to 10 hours.
[0072] In certain embodiments, the propylene polymer of the present
invention may be
produced in the presence of a chiral metallocene catalyst with an activator
and optional
scavenger. The use of single site catalysts is preferred to enhance the
homogeneity of the
polymer. As only a limited tacticity is needed many different forms of single
site catalyst may
be used. Possible single site catalysts are metallocenes, such as those
described in U.S. Pat.
No. 5,026,798, which have a single cyclopentadienyl ring, advantageously
substituted and/or
forming part of a polycyclic structure, and a hetero-atom, generally a
nitrogen atom, but
possibly also a phosphorus atom or phenoxy group connected to a group 4
transition metal,
preferably titanium but possibly zirconium or hafnium. A further example is
Me5CpTiMe3
activated with B(CF)3 as used to produce elastomeric polypropylene with an Mn
of up to 4
million. See Sassmannshausen, Bochmann, Rosch, Lilge, J. Organomet. Chem.
(1997) 548,
23-28.
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[0073] Other possible single site catalysts are metallocenes which are bis
cyclopentadienyl derivatives having a group transition metal, preferably
hafnium or
zirconium. Such metallocenes may be unbridged as in U.S. Patent No. 4,522,982
or U.S.
Patent No. 5,747,621. The metallocene may be adapted for producing a polymer
comprising
predominantly propylene derived units as in U.S. Patent No. 5,969,070 which
uses an
unbridged bis(2-phenyl indenyl) zirconium dichloride to produce a homogeneous
polymer
having a melting point of above 7 9C. The cyclopentadienyl rings may be
substituted and/or
part of polycyclic systems as described in the above U.S. patents.
[0074] Other possible metallocenes include those in which the two
cyclopentadienyl
groups are connected through a bridge, generally a single atom bridge such as
a silicon or
carbon atom with a choice of groups to occupy the two remaining valencies.
Such
metallocenes are described in U.S. Patent No. 6,048,950 which discloses
bis(indenyl)bis(dimethylsily1) zirconium dichloride and MAO; WO 98/27154 which
discloses
a dimethylsilvl bridged bisindenyl hafnium dimethyl together with a non-
coordinating anion
activator; EP 1070087 which discloses a bridged biscyclopentadienyl catalyst
which has
elements of asymmetry between the two cyclopentadienyl ligands to give a
polymer with
elastic properties; and the metallocenes described in U.S. Patent Nos.
6,448,358 and
6,265,212.
[0075] The manner of activation of the single site catalyst can vary.
Alumoxane and
preferably methyl alumoxane can be used. Higher molecular weights can be
obtained using
non-or weakly coordinating anion activators (NCA) derived and generated in any
of the ways
amply described in published patent art such as EP 277 004, EP 426 637, and
many others.
Activation generally is believed to involve abstraction of an anionic group
such as the methyl
group to form a metallocene cation, although according to some literature
zwitterions may be
produced. The NCA precursor can be an ion pair of a borate or aluminate in
which the
precursor cation is eliminated upon activation in some manner, e.g., trityl or
ammonium
derivatives of tetrakis pentafluorophenyl boron (See EP 277 004). The NCA
precursor can be
a neutral compound such as a borane, which is formed into a cation by the
abstraction of and
incorporation of the anionic group abstracted from the metallocene (See EP 426
638).
Specific Catalysts
[0076] As noted elsewhere herein, polymerizations in the different
reactors may in certain
embodiments be conducted in the presence of the same catalyst mixtures, and in
other
embodiments be conducted in the presence of different catalyst mixtures. As
used herein, the
term "catalyst mixture" (catalyst system) includes at least one catalyst and
at least one
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CA 03018952 2018-09-25
=
activator, although depending on the context, any reference herein to
"catalyst" usually also
implies an activator as well.
[00771 The
appropriate catalyst mixture may be delivered to the respective reactor in a
variety of ways. For example, it may be delivered as a solution or slurry,
either separately to
the reactor, activated in-line just prior to the reactor, or preactivated and
pumped as an activated
solution or slurry to the reactor. Polymerizations are carried out in each
reactor, in which
reactant components (e.g., desired monomers, comonomers, catalyst/activators,
scavengers,
and optional modifiers) are preferably added continuously to the appropriate
reactor. In some
embodiments, both catalyst mixtures are added to the first reactor, while in
other embodiments
110 one catalyst mixture is added to the first reactor and a different
catalyst mixture is added to the
second reactor (although in a sequential operation at least some of the first
catalyst mixture
from the first reactor may be directed to the second reactor together with the
product mixture
from the first reactor.
100781 In
preferred embodiments, two different catalysts are added as part of different
is reactant feeds, e.g., a "first catalyst," which may be part of a "first
reactant feed," and a "second
catalyst," which may be part of a "second reactant feed," although in at least
certain
embodiments (e.g., series reactors) both first and second catalysts are
present to some degree
in the second reactor feed, e.g., when the first effluent is supplied to a
second reactor.
Preferably, in at least certain embodiments, the first catalyst is a chiral
catalyst while the second
20 catalyst is a non-chiral catalyst.
[0079] In
certain embodiments of the processes and compositions, the same catalyst
mixture can be used for each of the first and second polymerizations, whether
series or parallel.
For example, in certain processes, certain catalyst mixtures described in U.S.
Patent No.
6,207,756 can be used in both polymerizations, particularly the portions
describing the catalyst
25 mixtures, e.g., column 8 line 20 through column 14, line 21. Preferred
catalysts are those that
are isospecific.
[0080] The first catalyst is preferably 1, l'-bis(4-
triethylsilylphenyOmethylene-
(cyclopentadienyl)(3,8-di-tertiary-buty1-1-fluroenyphafnium
dimethyl with
dimethylaninliniumtetrakis(pentafluorophenyl)borate activator. The second
catalyst is
30 preferably
dimethylsilylbis(indenyl)hafnium dimethyl with
dimethylaniliniumtetrakis(heptafiuoronaphthyl)borate activator.
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Useful Articles
[0081] Preferred compositions herein are particularly useful for film
applications.
[0082] The film can be a mono layer or multi-layer film. In an embodiment,
the film
comprises at least one layer, whether the only layer of the mono-layer film or
a layer of a
multi-layer film, comprising of from about 5 wt% to about 95 wt% of the
polymer
composition based on the total weight of the film layer. In an embodiment,
that film layer has
a thickness of about 1 um to about 2,000 um; about 5 um to about 150 um; and
about 10 um
to about 100 um; and about 20 um to about 90 um; and about 15 um to about 75
um. If part
of a multi-layer film structure, the film layer makes up at least 5 4) of the
total film thickness,
io or at least 10%, or at least 15%, or at least 17%, or at least 20%, or
at least 50% of the total
film thickness.
[0083] The films can be formed by any number of well-known lamination,
extrusion or
coextrusion techniques. Any of the blown, tentered or cast film techniques
commonly used is
suitable. For example, a resin composition can be extruded in a molten state
through a flat die
is and then cooled to form a film; in a cast film process. Alternatively,
the composition can be
extruded in a molten state through an annular die and then blown and cooled to
form a
tubular, blown film, which can then be used to make sacks or slit and unfolded
to form a flat
film.
[0084] Films with the polymer composition of the invention are expected to
possess an
20 excellent balance of mechanical properties, toughness, sealability and
cling/adhesive
properties. The films can also be used for shrink films and form fill and seal
applications
requiring abuse resistance. The films also possess good softness/feel and
optical/clarity
properties useful for food packaging at any temperature.
[0085] Specific applications include trash bags, adult care items,
agricultural films,
25 aluminum foil laminates, aluminum laminates, asphalt films, auto panel
films, bacon
packaging, bag-in-box liquid packaging applications, bakery goods, banana
film, batch
inclusion bags, bathroom tissue overwrap, biaxially oriented films, biaxially
oriented
polypropylene (BOPP) films, biscuits packages, boutique bags, bread bags,
bubble wrap,
building film, cake mix packaging, can liners, candy wrap, cardboard liquid
packaging,
30 carpet film, carry-out sacks, cement packaging, cereal liners, cheese
packaging, chemical
packaging, clarity films, coffee packaging, coin bags, collation shrink films,
confectionary
packaging, construction sheeting, construction film, consumer goods, consumer
trash bags,
continuous wrap, convenience packaging, cosmetics packaging, counter bags,
cover film,
cup/cutlery overwrap, deli and bakery wrap, detergent packaging, diaper
backsheet,
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disposables (diapers, sanitary, etc.), dry food packaging, dry grains, dunnage
bags, fertilizer,
fish & seafood packaging, food packaging, foundation film, freeze-dried
products, freezer
films, frozen food, fruit juice packaging, furniture bags, garden sacks,
garment bags,
geomembrane liners, gloves, gravel bags, green house films, grocery sacks,
heavy duty-sacks,
high clarity collation shrink film, high clarity films, high speed packaging
applications, high
stiffness overwrap film, horizontal form-fill-and-seal (HFFS) packaging,
household wrap,
hygiene overwrap films, ice bags, incision drape, industrial hardware
packaging, industrial
liner, industrial trash bags, industrial spare parts packaging, in store self-
service bags,
insulation bags, institutional liners, juice bags, kitchen rolls, landscaping
bags, lamination
films, light duty shrink film, lime bags, liners, liquid packaging, liquid and
granular food
packaging, low stiffness overwrap film, magazine overwrap, mailer bags,
mailers
envelopes/sacks, masking film, mayonnaise packaging, meat packaging, medical
products,
medical draping, medium duty bags, merchandise bags, metallized laminates,
military
hardware packaging, milk bags, milk powder packaging, modified atmosphere
packaging,
is mulch film, multi-wall sack liner, newspaper bags, nose tissue overwrap,
olive oil packaging,
packaging of beans, packaging of cementations products such as grout,
packaging of dry and
sharp products, pallet shrink film, pancake batter bags, paper handkerchief
overwrap, paper
laminates, pasta overwrap, pelletized polymer, perfume packaging, personal
care packaging,
pesticides packaging, pharmaceuticals packaging, pigment packaging, pizza
packaging,
polyamide laminates, polyester laminates, potato product packaging, potting
soil bags,
pouches, poultry packaging, pre-formed pouches, produce bags, produce
packaging, rack and
counter film, ready-made food packaging, ready meal packaging, retortable
product
packaging, films for the rubber industry, sandwich bags, salt bags, sausage
packaging,
seafood packaging, shipping sacks, shrink bags, shrink bundling film, shrink
film, shrink
shrouds, shrink tray, shrink wrap, snack food packaging, soft drink packaging,
soil bags, soup
packaging, spice packaging, stand up pouches, storage bags, stretch films,
stretch hooders,
stretch wrap, supermarket bags, surgical garb, takeout food bags, textile
films, refuse bags,
thermoformed containers, thin films, tissue overwrap, tobacco packaging,
tomato packaging,
ketchup packaging, trash bags, t-shirt bags, vacuum skin packaging, vegetable
packaging,
vertical form-fill-and-seal (FFS) packaging, horizontal FFS packaging, tubular
FFS
packaging, and water bottle packaging.
[0086] In addition to films, the blends described herein will find utility
in other
applications like, but not limited to extrusion coating, injection molding,
rotomolding, and
blow molding applications.
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[0087] Physical properties of the film can vary from those of the polymer
composition,
depending on the film forming techniques used. Certain unique properties of
the films are
described in more detail below.
Examples
[0088] In the Examples, P-1 and P-2 are comparative metallocene-catalyzed
ethylene-
propylene polymers prepared in a single reactor. The catalyst used for
preparing P-1 and P-2.
P-1 and P-2 were polymerized by the process described herein.
Copolymerizations were
carried out in a single-phase, liquid-filled, stirred tank reactor with
continuous flow of feeds
to the system and continuous withdrawal of products under equilibrium
conditions. All
io polymerizations were done in a solvent comprising predominantly C6
alkanes, referred to
generally as hexane solvent, using soluble metallocene catalysts and discrete,
non-
coordinating borate anion as co-catalysts. A homogeneous dilute solution of
tri-n-octyl
aluminum in hexane was used as a scavenger in concentrations appropriate to
maintain
reaction. Hydrogen, was added, if necessary, to control molecular weight. The
hexane solvent
was purified over beds of 3A mole sieves and basic alumina. All feeds were
pumped into the
reactors by metering pumps, except for the ethylene, which flowed as a gas
through a mass
flow meter/controller. Reactor temperature was controlled adiabatically by
controlled chilling
of the feeds and using the heat of polymerization to heat the reactor. The
reactors were
maintained at a pressure in excess of the vapor pressure of the reactant
mixture to keep the
reactants in the liquid phase. In this manner the reactors were operated
liquid full in a
homogeneous single phase. Ethylene and propylene feeds were combined into one
stream and
then mixed with a pre-chilled hexane stream. A hexane solution of a tri-n-
octyl aluminum
scavenger was added to the combined solvent and monomer stream just before it
entered the
reactor to further reduce the concentration of any catalyst poisons. A mixture
of the catalyst
components in solvent was pumped separately to the reactor and entered through
a separate
port. The reaction mixture was stirred aggressively using a magna-drive system
with three
directionally opposed tilt paddle stirrers set to about 750 rpm to provide
thorough mixing
over a broad range of solution viscosities. Flow rates were set to maintain an
average
residence time in the reactor of about 10 minutes.
[0089] P-4 and P-5 were inventive metallocene-catalyzed ethylene-propylene
copolymers. The first ethylene-rich polymer was prepared in a first reactor,
the second
propylene-rich polymer was prepared in a second reactor, and the ethylene-rich
polymer and
propylene-rich polymer were reactor blended. The first reactor had 1, l'-bis(4-
triethylsilylphenyl)methylene-(cyclopentadienyl)(3,8-di-tertiary-buty1-1-
fluroenyl)hafnium
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CA 03018952 2018-09-25
dimethyl catalyst and dimethylaninliniumtetrakis(pentafluorophenyl)borate
activator. The
second reactor had dimethylsilylbis(indenyl)hafnium dimethyl catalyst and
di methyl anil ini umtetraki s(heptafluoronaphthyl)borate activator.
[0090] P-4 through P-5 were polymerized by the process described herein.
Copolymerizations were carried out in two single-phase liquid-filled, stirred
tank reactors with
continuous flow of feeds to the system and continuous withdrawal of products
under
equilibrium conditions, configured in parallel. All polymerizations were done
in a solvent
comprising predominantly C6 alkanes, referred to generally as hexane solvent,
using soluble
metallocene catalysts and discrete, non-coordinating borate anion as co-
catalysts. Hydrogen,
was added, if necessary, to control molecular weight. The hexane solvent was
purified over
beds of 3A mole sieves and basic alumina. Reactor temperature was controlled
adiabatically
by controlled chilling of the feeds and using the heat of polymerization to
heat the reactor. The
reactors were maintained at a pressure in excess of the vapor pressure of the
reactant mixture
to keep the reactants in the liquid phase. In this manner the reactors were
operated liquid full
in a homogeneous single phase. Ethylene and propylene feeds were mixed with a
pre-chilled
hexane solvent stream. A hexane solution of a tri-n-octyl aluminum scavenger
was added to
the combined solvent and monomer stream just before it entered the reactor to
further reduce
the concentration of any catalyst poisons. A mixture of the catalyst
components in solvent was
pumped separately to the reactor and entered through a separate port. The
reaction mixture was
stirred aggressively to provide thorough mixing over a broad range of solution
viscosities. Flow
rates were set to maintain an average residence time in the reactor of about
10 minutes. On
exiting the reactor, the copolymer mixture from each reactor was combined and
subjected to
quenching, a series of concentration steps, heat and vacuum stripping and
pelletization, the
general conditions of which are described in International Patent Publication
WO 99/45041.
Properties of P-4 through P-5 are included below in Table 1 and were measured
according to
the methods described herein.
[0091] P-3 is VistalonTm805, an ethylene polymer commercially available
from
ExxonMobil Chemical Company.
100921 C-1 and C-2 are physical blends of commercial ethylene polymer and
propylene
polymers, available from ExxonMobil Chemical Company. C-1 is a physical blend
of 90 wt%
VistalonTm805 and 10 wt% VistamaxxTm3020. C-2 is a physical blend of 90 wt%
VistalonTm805 and 10 wt% VistamaxxTm6100. The two components in C-1 and C-2
were
physically blended in a ZSK twin screw extruder. The batch size for twin screw
- 22 -
CA 03018952 2018-09-25
WO 2017/172102 PCT/US2017/018285
compounding was 30 kg. Compounding in the ZSK extruder was accomplished by
tumble-
blending the two components (listed in Table 1) in a V-cone blender and
introducing the
blend into the extruder hopper. The melt temperature was maintained at 230 C.
- 23 -
0
Table 1 - Ethylene-Propylene Copolymer Properties
=
...
--4
P-1 P-2 P-3 P-4
P-5 C-1 C-2 -,
-1
t.)
-,
Component]
=
l=.)
Ethylene Content, wt% (NMR) 82.5 76.7
Ethylene Content, wt % (IR) 85.1 78.5 78.0 77.8
77.1 78.0 78.0
ML (1 +4, 125 C) 35 46 33 32
41
MI (190 C/2.16 kg)
0.23
Component 2
P
Ethylene Content, wt% (NMR) N/A N/A N/A
9.2 14.7 .
0
Ethylene Content, wt ()/0 (IR) N/A N/A N/A 10.7
17.4 12.0 16.0
MFR (230 C/2.16 kg) N/A N/A N/A 2.4
2.4 8.5 3.0 .
0,
,
i' Blend (Component I and Component 2)
' o,
Polysplit (% of Component 1 in Blend) 100 100 100 90
90 90 90
Ethylene Content, wt% (NMR) 82.5 76.7
71.1
Ethylene Content, wt % (IR) 85.1 78.5 78.0 71.8
74.3
Ethylene Content calculated by polysplit N/A N/A N/A 71.1
71.1 71.4 71.8
-o
Melt Index, g/10 min 0.20 0.19 0.22
0.22 n
AHf, J/g (211d melt) 74 58 55
50 25 30 u)
t.1
=
Mw/Mn (Mw measured MALLS, Mn measured DRI) 2.2 2.1 2.0
2.1 .
-1
=
r,
l=.)
W
'A
CA 03018952 2018-09-25
WO 2017/172102 PCMJS2017/018285
[0093] To test the polymer compositions in a film application, a five layer
film having a
total thickness of 50 um was prepared. Each film had an outside bubble skin
layer (thickness
of 12.5 um), subskin layer (thickness of 6.25 um), core layer (thickness of
12.5 um), subskin
layer (thickness of 6.25 um), and inside bubble skin layer (thickness of 12.5
um) was formed.
The seven film samples (five comparative and two inventive) are detailed below
in Table 2.
The films were produced on a 5 layer film blowing line using the following
process
conditions: Total Output Rate (kg/h) = 120 - 229; Blow Up Ratio = 2.5; Die
diameter (mm) =
280; Die gap (mm) = 1.4; Haul-off speed for high throughput (220-229 kg/h)
(m/min) = 38.1
and for low throughputs (120-130 kg/h) (m/min) = 20; Frost Line Height (mm) =
800 (low
throughput) ¨ and from 850 ¨ 1000 (high throughput); Temperature settings (
C): Extruder D
= 190 (outside bubble skin); Extruder C = 190 (outside bubble sub-skin);
Extruder B = 220
(core of the bubble); Extruder A = 180-190 (inside bubble sub-skin); Extruder
E = 190
(inside bubble skin); Die head = 220.
[0094] Each film sample was tested for the following film properties:
force, elongation,
seal energy, and failure mode. The following method was used, based on ASTM F-
2029, to
prepare the films for the seal experiments: the produced films were
conditioned under
controlled temperature and humidity (23 2 C and 50 5% relative humidity)
for at least 48
hours before seal preparation. Film samples were cut out from the film role in
the machine
direction to the dimensions 250 mm x 30 mm. The prepared 30mm wide film
samples were
folded in the long direction with the sealing layers facing each other. For
the reported results,
the film samples were folded so that the outside bubble skin layers of the
film touched each
other to be sealed. The prepared sealing sample was further covered with a
Teflon sheet in
order to prevent the film from adhering to the sealing bars. The whole
construction was
submitted to a heat sealing with heated sealing bars at the desired seal
temperature with a
pressure of 0.5 N/mm2 for 0.5 seconds over a sealing width of 5 mm and cooled
down under
normal room temperature conditions. For all the samples, the seal temperature
was set at
180 C. The seal bar touched the film sample at least lcm away from the edge of
the film. The
formed sealed area had the dimensions of 30 mm x 5 mm. The folded and sealed
film sample
was then cut at the fold. The sealed samples were conditioned under controlled
temperature
and humidity (23 2 C and 50 5% relative humidity) for at least 48 hours
before the actual
seal rupture testing. After preparing and conditioning the samples, the
conditioned sealed 30
mm wide film samples were further cut to 15 mm width by cutting away the left
and right
sides of the samples, keeping only the middle part of the sample. The samples
were then
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CA 03018952 2018-09-25
WO 2017/172102 PCMJS2017/018285
submitted to tensile testing on an instrumented tensile bench. The speed of
the tensile test was
set at 500 mmlsec. A minimum amount of 5 samples was measured to test the
Energy at
Break (or Seal Energy) per film sample. All properties utilized for the
evaluation of the
failure mode are reported in Table 3. The average of the measured values is
reported and a
failure mode for each sample is provided.
[0095] Failure mode is reported in Table 2. A Failure Mode of "Peeling
without
Elongation" means the force at maximum was medium, the force at break was low,
the
elongation at the force at max was low, and the elongation at break was low. A
Failure Mode
of -Delamination without Elongation" means the force at maximum was high, the
force at
break was low, the elongation at the force at max was low, and the elongation
at break was
low. A Failure Mode of "Delamination with Elongation" means the force at
maximum was
high, the force at break was low, the elongation at the force at max was low,
and the
elongation at break was high. A Failure Mode of -Elongation with Peeling"
means the force
at maximum was high, the force at break was low, the elongation at the force
at max was
high, and the elongation at break was high. A Failure Mode of "Elongation with
Delamination" means the force at maximum was high, the force at break was low,
the
elongation at the force at max was high, and the elongation at break was high.
A Failure
Mode of "Elongation with Edge Break" means the force at maximum was high, the
force at
break was high, the elongation at the force at max was high, and the
elongation at break was
high.
- 26 -
0
Table 2 - Multi-Layer Film and Properties
t.)
=
---11
Comparative Film 3 Comparative
Comparative -1
Film 6
Film 7 "
Film 1 Film 2 Film 4
Film 5 S'
IV
Layer 1 (outside 95 wt% ExceedTM 1018KB and 5 wt%
LD150BW
bubble skin)
Layer 2 (subskin) P-3 C-1 C-1 P-1
P-2 P-4 P-5
Layer 3 (core) Moplen HP456J
Layer 4 (subskin) P-3 C-2 C-2 P-1
P-2 P-4 P-5
Layer 5 (inside 95 wt% ExceedTM 1018KB and 5 wt%
LD150BW
P
bubble skin)
.
Failure Mode 4 samples: 2 samples: edge break
1 sample: 2 samples: 30% 4 samples: 5 0
(5 samples) edge break with with
elongation/ delaminated delamination delaminatio samples:
elongation/ 3 samples: delaminated with
with 70% edge n with edge .
0,
6 1 sample: with elongation elongation/1
break with elongation; break ,
--.1
.
,
delaminated with sample: 10%
elongation/2 1 sample: with
o,
elongation delamination
samples: edge edge break elongati
samples with 90% edge
break with with on
delaminated break with
elongation/1 elongation
elongation/ 2
sample: edge
samples: edge
break with
break/ 1
elongation
sample: edge
-0
n
break with
-,=-1
elongation
u)
t.,
=
-1
=
r,
IV
W
!A
0
Table 3 - Multi-Layer Film Properties
t.)
=
---11
,
Comparative Comparative
Comparative -1
Film 2 Film 3 Film 6
Film 7 " Film 1 Film 4 Film 5 =
IV
Force at Fmax 11.5 14.2 13.8 12.1
11.9 13.9 13.7
(N/15 mm)
Elongation at 13 386 382 17.1
17 344 360
Fmax (%)
Force at break 2.33 11.4 10.7 10.2
10.1 9.8 13.6
(N/15 mm)
Elongation at 148 419 434 110
131 423 366
break (%)
p
Energy at Fmax 0.1 2.23 2.1 0.08
0.08 2.0 2.07 .
(J/15 mm)
0
.,
Seal Energy 0.37 2.4 2.4 0.56
0.69 2.3 2.1
(J/15mm)
.
0,
,
Total Output 120 120 120 228
225 120 229 .
,
11`) Rate (kg/hr)
o,
i
Mode of Sealing Sealed Sealed Sealed Sealed
Sealed Sealed Sealed
Inside/Inside Inside/Inside Outside/Outside
Inside/Inside Inside/Inside Inside/Inside Inside/Inside
(P3/P3-P3/P3) (C2/C1-C1/C2) (C1/C2-C2/C1) (P1/P1-1/P1) (P2/P2-P2/P2) (P4/P4-
P4/P4) (P5/P5-P5/P5)
-o
n
c.)
t.,
=
¨
-1
=
r,
IV
W
!A
CA 03018952 2018-09-25
=
[0096] As Tables 2 and 3 show, Films 2, 3, 6, and 7 having inventive dual
blend polymer
compositions in the subskin layers showed favorably high seal energies. In
contrast, films with
PE polymers in the subskin (i.e., Comparative Film 1 having only VistaIon
polymers) showed
unfavorably low seal energies due to poor compatibility between the outside
bubble skin layer
1 (PE-based layer) and the Core layer (PP-based layer) and between the inside
bubble layer
(PE-based layer) and the Core layer (PP-based layer). As C-1 and C-2 are
blends of commercial
samples, it is expected that these blends are more homogenous than a reactor
blend of novel
non-commercial materials P-4 and P-5. Films 6 and 7 having inventive dual
reactor blend
polymer compositions in the subskin layers show favorably high seal energies
(high force and
high elongation). Comparative films 4 and 5, produced with single reactor
polymers, show
poor seal energies (relatively high force with low elongation). The subskin in
these films is
not functioning as a compatibilizer or tie layer due to the use of only a
single component
resulting in poor seal energy.
[0097] Certain embodiments and features have been described using a set of
numerical
upper limits and a set of numerical lower limits. It should be appreciated
that ranges from any
lower limit to any upper limit are contemplated unless otherwise indicated.
All numerical
values are "about" or "approximately" the indicated value, and take into
account experimental
error and variations that would be expected by a person having ordinary skill
in the art.
[0098] As used herein, the phrases "substantially no," and "substantially
free of' are
intended to mean that the subject item is not intentionally used or added in
any amount, but
may be present in very small amounts existing as impurities resulting from
environmental or
process conditions.
[0099] To the extent a term used in a claim is not defined above, it
should be given the
broadest definition persons in the pertinent art have given that term as
reflected in at least one
printed publication or issued patent.
[0100] While the foregoing is directed to embodiments of the present
invention, other and
further embodiments of the invention may be devised without departing from the
basic scope
thereof, and the scope thereof is determined by the claims that follow.
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