U.S. patent application number 17/370022 was filed with the patent office on 2022-05-12 for particle size control of metallocene catalyst systems in loop slurry polymerization reactors.
The applicant listed for this patent is Chevron Phillips Chemical Company LP. Invention is credited to Carlton E. Ash, Kathy S. Clear, Carlos A. Cruz, Max P. McDaniel, Jeremy M. Praetorius, Eric D. Schwerdtfeger, Youlu Yu.
Application Number | 20220144985 17/370022 |
Document ID | / |
Family ID | |
Filed Date | 2022-05-12 |
United States Patent
Application |
20220144985 |
Kind Code |
A1 |
McDaniel; Max P. ; et
al. |
May 12, 2022 |
Particle Size Control of Metallocene Catalyst Systems in Loop
Slurry Polymerization Reactors
Abstract
Catalyst compositions containing a metallocene compound, a solid
activator, and a co-catalyst, in which the solid activator or the
supported metallocene catalyst has a d50 average particle size of
15 to 50 .mu.m and a particle size distribution of 0.5 to 1.5, can
be contacted with an olefin in a loop slurry reactor to produce an
olefin polymer. A representative ethylene-based polymer produced
using the catalyst composition has excellent dart impact strength
and low gels, and can be characterized by a HLMI from 4 to 10 g/10
min, a density from 0.944 to 0.955 g/cm.sup.3, a higher molecular
weight component with a Mn from 280,000 to 440,000 g/mol, and a
lower molecular weight component with a Mw from 30,000 to 45,000
g/mol and a ratio of Mz/Mw ranging from 2.3 to 3.4.
Inventors: |
McDaniel; Max P.;
(Bartlesville, OK) ; Ash; Carlton E.; (Owasso,
OK) ; Clear; Kathy S.; (Bartlesville, OK) ;
Schwerdtfeger; Eric D.; (Bartlesville, OK) ; Cruz;
Carlos A.; (Kingwood, TX) ; Praetorius; Jeremy
M.; (Bartlesville, OK) ; Yu; Youlu;
(Bartlesville, OK) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Chevron Phillips Chemical Company LP |
The Woodlands |
TX |
US |
|
|
Appl. No.: |
17/370022 |
Filed: |
July 8, 2021 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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17092394 |
Nov 9, 2020 |
11124586 |
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17370022 |
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International
Class: |
C08F 210/16 20060101
C08F210/16; C08J 5/18 20060101 C08J005/18 |
Claims
1. An ethylene polymer having: a high load melt index (HLMI) in a
range from 4 to 10 g/10 min; a density in a range from 0.944 to
0.955 g/cm.sup.3; and a higher molecular weight component and a
lower molecular weight component, wherein: the higher molecular
weight component has a Mn in a range from 280,000 to 440,000 g/mol;
and the lower molecular weight component has a Mw in a range from
30,000 to 45,000 g/mol and a ratio of Mz/Mw in a range from 2.3 to
3.4.
2. An article comprising the ethylene polymer of claim 1.
3. The article of claim 2, wherein the ethylene polymer comprises
an ethylene/1-butene copolymer, an ethylene/1-hexene copolymer,
and/or an ethylene/1-octene copolymer.
4. The ethylene polymer of claim 1, wherein: the HLMI is from 5 to
9 g/10 min; the density is from 0.945 to 0.953 g/cm.sup.3; the Mn
is from 290,000 to 410,000 g/mol; the Mw is from 31,000 to 42,000
g/mol; and the ratio of Mz/Mw is from 2.4 to 3.3.
5. The ethylene polymer of claim 1, wherein: an amount of the lower
molecular weight component, based on the total polymer, is in a
range from 56 to 72 wt %; and the ethylene polymer comprises an
ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, and/or
an ethylene/1-octene copolymer.
6. The ethylene polymer of claim 5, wherein the ethylene polymer is
characterized by a film gel count of less than 50 gels per ft.sup.2
of 25 micron film.
7. A film comprising the ethylene polymer of claim 5.
8. The film of claim 7, wherein the film has: a dart impact from
150 to 750 g/mil; and a gel count of less than 50 gels per ft.sup.2
of film.
9. The ethylene polymer of claim 1, wherein the ethylene polymer
has: a CY-a parameter from 0.45 to 0.65; a relaxation time from 1.5
to 4 sec; a viscosity at 100 sec.sup.-1 from 2000 to 3600 Pa-sec;
and a ratio of viscosity at 0.1 sec.sup.-1 to viscosity at 100
sec.sup.-1 from 38 to 72.
10-20. (canceled)
21. The ethylene polymer of claim 1, wherein the ethylene polymer
comprises an ethylene/1-butene copolymer, an ethylene/1-hexene
copolymer, and/or an ethylene/1-octene copolymer.
22. The ethylene polymer of claim 21, wherein the ethylene polymer
contains less than 0.1 ppm by weight, independently, of Mg, V, Ti,
and Cr.
23. The ethylene polymer of claim 21, wherein: a Mw of the ethylene
polymer is in a range from 230,000 to 330,000 g/mol; and a ratio of
Mw/Mn of the ethylene polymer is in a range from 20 to 45.
24. An article comprising the ethylene polymer of claim 23.
25. A film comprising the ethylene polymer of claim 23, wherein the
film has: a dart impact from 150 to 750 g/mil; and a gel count of
less than 50 gels per ft.sup.2 of film.
26. The ethylene polymer of claim 23, wherein a Mz of the lower
molecular weight component is in a range from 75,000 to 120,000
g/mol.
27. The ethylene polymer of claim 4, wherein the ethylene polymer
comprises an ethylene/.alpha.-olefin copolymer.
28. The ethylene polymer of claim 27, wherein the ethylene polymer
is characterized by a film gel count of less than 50 gels per
ft.sup.2 of 25 micron film.
29. The ethylene polymer of claim 4, wherein an amount of the lower
molecular weight component, based on the total polymer, is in a
range from 56 to 72 wt %.
30. The ethylene polymer of claim 4, wherein the ethylene polymer
has: a CY-a parameter from 0.45 to 0.65; a relaxation time from 1.5
to 4 sec; a viscosity at 100 sec.sup.-1 from 2000 to 3600 Pa-sec;
and a ratio of viscosity at 0.1 sec.sup.-1 to viscosity at 100
sec.sup.-1 from 38 to 72.
31. An article comprising the ethylene polymer of claim 30.
32. The ethylene polymer of claim 30, wherein the ethylene polymer
comprises an ethylene/1-butene copolymer, an ethylene/1-hexene
copolymer, and/or an ethylene/1-octene copolymer.
33. The ethylene polymer of claim 32, wherein a Mz of the lower
molecular weight component is in a range from 75,000 to 120,000
g/mol.
Description
FIELD OF THE INVENTION
[0001] The present disclosure generally relates to loop slurry
polymerization processes for producing ethylene polymers, and more
particularly, relates to the use of metallocene-based catalyst
systems with particular particle size attributes in these loop
slurry polymerization processes.
BACKGROUND OF THE INVENTION
[0002] Improper particle size features of metallocene-based
catalyst systems can lead to operational difficulties during
ethylene/.alpha.-olefin polymerizations in loop slurry reactors, as
well as poor and inconsistent properties of the resulting polymer.
It would be beneficial to develop catalyst systems and
polymerization processes that overcome these drawbacks.
Accordingly, it is to these ends that the present invention is
generally directed.
SUMMARY OF THE INVENTION
[0003] This summary is provided to introduce a selection of
concepts in a simplified form that are further described below in
the detailed description. This summary is not intended to identify
required or essential features of the claimed subject matter. Nor
is this summary intended to be used to limit the scope of the
claimed subject matter.
[0004] The present invention generally relates, in one aspect, to
metallocene-based catalyst compositions and to slurry
polymerization processes using the catalyst compositions. Such
catalyst compositions can comprise a metallocene compound (one or
more than one), a solid activator, and optionally, a co-catalyst.
The solid activator (or the supported metallocene catalyst) can
have a d50 average particle size in a range from 15 to 50 .mu.m and
a particle size span ((d90-d10)/d50) in a range from 0.5 to 1.5.
Polymerization processes using the metallocene-based catalyst
composition can comprise contacting the catalyst composition with
an olefin monomer and an optional olefin comonomer in a
polymerization reactor system comprising a loop slurry reactor
under polymerization conditions to produce an olefin polymer.
[0005] Ethylene polymer powder (or fluff) produced by the
polymerization processes can have, in another aspect, a d50 average
particle size in a range from 150 to 600 .mu.m, a particle size
span in a range from 0.5 to 1.6, less than or equal to 20 wt. % of
the composition with a particle size of less than 100 .mu.m, and
less than or equal to 5 wt. % of the composition with a particle
size of greater than 1000 .mu.m.
[0006] In yet another aspect, the present invention also is
directed to ethylene polymers characterized by a high load melt
index (HLMI) in a range from 4 to 10 g/10 min, a density in a range
from 0.944 to 0.955 g/cm.sup.3, and a higher molecular weight
component and a lower molecular weight component, in which the
higher molecular weight component can have a Mn in a range from
280,000 to 440,000 g/mol, and the lower molecular weight component
can have a Mw in a range from 30,000 to 45,000 g/mol and a ratio of
Mz/Mw in a range from 2.3 to 3.4. The lower molecular weight
component can be the majority of the ethylene polymer, typically
ranging from 56 to 72 wt. % of the ethylene polymer, which is
typically in the form of pellets or beads.
[0007] Both the foregoing summary and the following detailed
description provide examples and are explanatory only. Accordingly,
the foregoing summary and the following detailed description should
not be considered to be restrictive. Further, features or
variations may be provided in addition to those set forth herein.
For example, certain aspects and embodiments may be directed to
various feature combinations and sub-combinations described in the
detailed description.
BRIEF DESCRIPTION OF THE FIGURES
[0008] FIG. 1 presents a plot of the particle size distributions of
the Inventive 1, Inventive 2, Comparative 1, and Comparative 2
solid activators.
[0009] FIG. 2 presents a plot of the particle size distributions of
the Inventive 1, Inventive 2, Comparative 1, and Comparative 2
polymer powders.
[0010] FIG. 3 presents a plot of film gel count versus time as the
Comparative 2 catalyst is transitioned to the Inventive 1
catalyst.
[0011] FIG. 4 presents a plot of segregation test results for the
Comparative 2 polymer powder.
[0012] FIG. 5 presents a plot of the flotation density distribution
of the Inventive 1, Inventive 2, and Comparative 2 polymer
powders.
[0013] FIG. 6 presents a plot of the molecular weight distributions
of the polymers of Examples 1, 4, 12, 18, 21, and 36.
DEFINITIONS
[0014] To define more clearly the terms used herein, the following
definitions are provided. Unless otherwise indicated, the following
definitions are applicable to this disclosure. If a term is used in
this disclosure but is not specifically defined herein, the
definition from the IUPAC Compendium of Chemical Terminology, 2nd
Ed (1997), can be applied, as long as that definition does not
conflict with any other disclosure or definition applied herein, or
render indefinite or non-enabled any claim to which that definition
is applied. To the extent that any definition or usage provided by
any document incorporated herein by reference conflicts with the
definition or usage provided herein, the definition or usage
provided herein controls.
[0015] Herein, features of the subject matter are described such
that, within particular aspects, a combination of different
features can be envisioned. For each and every aspect and/or
feature disclosed herein, all combinations that do not
detrimentally affect the designs, compositions, and/or methods
described herein are contemplated with or without explicit
description of the particular combination. Additionally, unless
explicitly recited otherwise, any aspect and/or feature disclosed
herein can be combined to describe inventive features consistent
with the present disclosure.
[0016] While compositions and methods are described herein in terms
of "comprising" various components or steps, the compositions and
methods also can "consist essentially of" or "consist of" the
various components or steps, unless stated otherwise. For example,
a catalyst composition consistent with aspects of the present
invention can comprise; alternatively, can consist essentially of;
or alternatively, can consist of; catalyst component I, catalyst
component II, a solid activator, and a co-catalyst.
[0017] The terms "a," "an," "the," etc., are intended to include
plural alternatives, e.g., at least one, unless otherwise
specified. For instance, the disclosure of "a co-catalyst" or "a
metallocene compound" is meant to encompass one, or mixtures or
combinations of more than one, co-catalyst or metallocene compound,
respectively, unless otherwise specified.
[0018] Generally, groups of elements are indicated using the
numbering scheme indicated in the version of the periodic table of
elements published in Chemical and Engineering News, 63(5), 27,
1985. In some instances, a group of elements can be indicated using
a common name assigned to the group; for example, alkali metals for
Group 1 elements, alkaline earth metals for Group 2 elements,
transition metals for Group 3-12 elements, and halogens or halides
for Group 17 elements.
[0019] For any particular compound disclosed herein, the general
structure or name presented is also intended to encompass all
structural isomers, conformational isomers, and stereoisomers that
can arise from a particular set of substituents, unless indicated
otherwise. Thus, a general reference to a compound includes all
structural isomers unless explicitly indicated otherwise; e.g., a
general reference to pentane includes n-pentane, 2-methyl-butane,
and 2,2-dimethylpropane, while a general reference to a butyl group
includes an n-butyl group, a sec-butyl group, an iso-butyl group,
and a tert-butyl group. Additionally, the reference to a general
structure or name encompasses all enantiomers, diastereomers, and
other optical isomers whether in enantiomeric or racemic forms, as
well as mixtures of stereoisomers, as the context permits or
requires. For any particular formula or name that is presented, any
general formula or name presented also encompasses all
conformational isomers, regioisomers, and stereoisomers that can
arise from a particular set of substituents.
[0020] The term "substituted" when used to describe a group, for
example, when referring to a substituted analog of a particular
group, is intended to describe any non-hydrogen moiety that
formally replaces a hydrogen in that group, and is intended to be
non-limiting. A group or groups can also be referred to herein as
"unsubstituted" or by equivalent terms such as "non-substituted,"
which refers to the original group in which a non-hydrogen moiety
does not replace a hydrogen within that group. Unless otherwise
specified. "substituted" is intended to be non-limiting and include
inorganic substituents or organic substituents as understood by one
of ordinary skill in the art.
[0021] The term "hydrocarbon" whenever used in this specification
and claims refers to a compound containing only carbon and
hydrogen. Other identifiers can be utilized to indicate the
presence of particular groups in the hydrocarbon (e.g., halogenated
hydrocarbon indicates the presence of one or more halogen atoms
replacing an equivalent number of hydrogen atoms in the
hydrocarbon). The term "hydrocarbyl group" is used herein in
accordance with the definition specified by IUPAC: a univalent
group formed by removing a hydrogen atom from a hydrocarbon (that
is, a group containing only carbon and hydrogen). Non-limiting
examples of hydrocarbyl groups include alkyl, alkenyl, aryl, and
aralkyl groups, amongst other groups.
[0022] The term "polymer" is used herein generically to include
olefin homopolymers, copolymers, terpolymers, and the like, as well
as alloys and blends thereof. The term "polymer" also includes
impact, block, graft, random, and alternating copolymers. A
copolymer is derived from an olefin monomer and one olefin
comonomer, while a terpolymer is derived from an olefin monomer and
two olefin comonomers. Accordingly, "polymer" encompasses
copolymers and terpolymers derived from any olefin monomer and
comonomer(s) disclosed herein. Similarly, the scope of the term
"polymerization" includes homopolymerization, copolymerization, and
terpolymerization. Therefore, an ethylene polymer includes ethylene
homopolymers, ethylene copolymers (e.g., ethylene/.alpha.-olefin
copolymers), ethylene terpolymers, and the like, as well as blends
or mixtures thereof. Thus, an ethylene polymer encompasses polymers
often referred to in the art as LLDPE (linear low density
polyethylene) and HDPE (high density polyethylene). As an example,
an olefin copolymer, such as an ethylene copolymer, can be derived
from ethylene and a comonomer, such as 1-butene, 1-hexene, or
1-octene. If the monomer and comonomer were ethylene and 1-hexene,
respectively, the resulting polymer can be categorized an as
ethylene/1-hexene copolymer. The term "polymer" also includes all
possible geometrical configurations, unless stated otherwise, and
such configurations can include isotactic, syndiotactic, and random
symmetries. Moreover, unless stated otherwise, the term "polymer"
also is meant to include all molecular weight polymers, and is
inclusive of lower molecular weight polymers.
[0023] The term "co-catalyst" is used generally herein to refer to
compounds such as aluminoxane compounds, organoboron or
organoborate compounds, ionizing ionic compounds, organoaluminum
compounds, organozinc compounds, organomagnesium compounds,
organolithium compounds, and the like, that can constitute one
component of a catalyst composition, when used, for example, in
addition to a solid activator. The term "co-catalyst" is used
regardless of the actual function of the compound or any chemical
mechanism by which the compound may operate.
[0024] The term "solid activator" is used herein to indicate a
solid, inorganic oxide of relatively high porosity, which can
exhibit Lewis acidic or Bronsted acidic behavior, and which has
been treated with an electron-withdrawing component, typically an
anion, and which is calcined. The electron-withdrawing component is
typically an electron-withdrawing anion source compound. Thus, the
solid activator can comprise a calcined contact product of at least
one solid oxide with at least one electron-withdrawing anion source
compound. Typically, the solid activator comprises at least one
acidic solid oxide compound. The "solid activator" of the present
invention can be a chemically-treated solid oxide. The term "solid
activator" is used to imply that these components are not inert,
and such components should not be construed as an inert component
of the catalyst composition. The term "activator," as used herein,
refers generally to a substance that is capable of converting a
metallocene component into a catalyst that can polymerize olefins,
or converting a contact product of a metallocene component and a
component that provides an activatable ligand (e.g., an alkyl, a
hydride) to the metallocene, when the metallocene compound does not
already comprise such a ligand, into a catalyst that can polymerize
olefins. This term is used regardless of the actual activating
mechanism. Illustrative activators include solid activators,
aluminoxanes, organoboron or organoborate compounds, ionizing ionic
compounds, and the like. Aluminoxanes, organoboron or organoborate
compounds, and ionizing ionic compounds generally are referred to
as activators if used in a catalyst composition in which a solid
activator is not present. If the catalyst composition contains a
solid activator, then the aluminoxane, organoboron or organoborate,
and ionizing ionic materials are typically referred to as
co-catalysts.
[0025] The term "metallocene" as used herein describes compounds
comprising at least one .eta..sup.3 to
.eta..sup.5-cycloalkadienyl-type moiety, wherein .eta..sup.3 to
.eta..sup.5-cycloalkadienyl moieties include cyclopentadienyl
ligands, indenyl ligands, fluorenyl ligands, and the like,
including partially saturated or substituted derivatives or analogs
of any of these. Possible substituents on these ligands can include
H, therefore this invention comprises ligands such as
tetrahydroindenyl, tetrahydrofluorenyl, octahydrofluorenyl,
partially saturated indenyl, partially saturated fluorenyl,
substituted partially saturated indenyl, substituted partially
saturated fluorenyl, and the like. In some contexts, the
metallocene is referred to simply as the "catalyst," in much the
same way the term "co-catalyst" is used herein to refer to, for
example, an organoaluminum compound.
[0026] The terms "catalyst composition." "catalyst mixture."
"catalyst system," and the like, do not depend upon the actual
product or composition resulting from the contact or reaction of
the initial components of the disclosed or claimed catalyst
composition/mixture/system, the nature of the active catalytic
site, or the fate of the co-catalyst, metallocene compound, or the
solid activator, after combining these components. Therefore, the
terms "catalyst composition," "catalyst mixture," "catalyst
system," and the like, encompass the initial starting components of
the composition, as well as whatever product(s) may result from
contacting these initial starting components, and this is inclusive
of both heterogeneous and homogenous catalyst systems or
compositions. The terms "catalyst composition." "catalyst mixture,"
"catalyst system," and the like, can be used interchangeably
throughout this disclosure.
[0027] The term "contact product" is used herein to describe
compositions wherein the components are contacted together in any
order, in any manner, and for any length of time, unless otherwise
specified. For example, the components can be contacted by blending
or mixing. Further, contacting of any component can occur in the
presence or absence of any other component of the compositions
described herein. Combining additional materials or components can
be done by any suitable method. Further, the term "contact product"
includes mixtures, blends, solutions, slurries, reaction products,
and the like, or combinations thereof. Although "contact product"
can include reaction products, it is not required for the
respective components to react with one another. Similarly, the
term "contacting" is used herein to refer to materials which can be
blended, mixed, slurried, dissolved, reacted, treated, or otherwise
combined in some other manner.
[0028] Although any methods, devices, and materials similar or
equivalent to those described herein can be used in the practice or
testing of the invention, the typical methods, devices, and
materials are herein described.
[0029] All publications and patents mentioned herein are
incorporated herein by reference for the purpose of describing and
disclosing, for example, the constructs and methodologies that are
described in the publications, which might be used in connection
with the presently described invention.
[0030] Several types of ranges are disclosed in the present
invention. When a range of any type is disclosed or claimed, the
intent is to disclose or claim individually each possible number
that such a range could reasonably encompass, including end points
of the range as well as any sub-ranges and combinations of
sub-ranges encompassed therein. For example, when a chemical moiety
having a certain number of carbon atoms is disclosed or claimed,
the intent is to disclose or claim individually every possible
number that such a range could encompass, consistent with the
disclosure herein. For example, the disclosure that a moiety is a
C.sub.1 to C.sub.18 hydrocarbyl group, or in alternative language,
a hydrocarbyl group having from 1 to 18 carbon atoms, as used
herein, refers to a moiety that can have 1, 2, 3, 4, 5, 6, 7, 8, 9,
10, 11, 12, 13, 14, 15, 16, 17, or 18 carbon atoms, as well as any
range between these two numbers (for example, a C.sub.1 to C.sub.8
hydrocarbyl group), and also including any combination of ranges
between these two numbers (for example, a C.sub.2 to C.sub.4 and a
C.sub.2 to C.sub.16 hydrocarbyl group).
[0031] Similarly, another representative example follows for the
ratio of Mw/Mn of an ethylene polymer consistent with aspects of
this invention. By a disclosure that the ratio of Mw/Mn can be in a
range from 20 to 45, the intent is to recite that the ratio of
Mw/Mn can be any ratio in the range and, for example, can include
any range or combination of ranges from 20 to 45, such as from 20
to 42, from 20 to 30, or from 35 to 45, and so forth. Likewise, all
other ranges disclosed herein should be interpreted in a manner
similar to these examples.
[0032] In general, an amount, size, formulation, parameter, range,
or other quantity or characteristic is "about" or "approximate"
whether or not expressly stated to be such. Whether or not modified
by the term "about" or "approximately," the claims include
equivalents to the quantities or characteristics.
DETAILED DESCRIPTION OF THE INVENTION
[0033] The present invention is directed generally to single
metallocene and dual metallocene catalyst systems, controlling the
particle size of the solid activator in these catalyst systems,
methods for using the catalyst systems to polymerize olefins in
loop slurry reactors, the polymer resins produced using such
catalyst systems, and films and other articles of manufacture
produced from these polymer resins.
[0034] Catalyst particle sizes that perform well in certain
fluidized bed gas phase processes are not transferable to loop
slurry processes, due in part to differences in catalyst
loading/feeding and in downstream polymer transfer, as well as
particle settling efficiency in a gaseous medium versus a liquid
diluent. For loop slurry processes, the benefits of smaller
catalyst particle sizes generally include lower gels, more surface
area which increases the potential for collisions and mass
transfer, higher saltation velocities, greater potential reactor
mass solids, longer reactor residence times, higher activities, and
more efficient purge capability. However, there are significant
drawbacks to the use of small particle sizes (fines), in
particular, difficulties with activation and transfer of the
activator/catalyst into the reactor, issues of downstream
powder/fluff transfer (since smaller catalyst particles generally
make smaller polymer particles), and higher slurry viscosity due
the greater surface area of the fine particles. An objective of
this invention, therefore, is to target a moderate average catalyst
particle size and with a narrow particle size distribution, such
that the only a small amount of catalyst particles are fines (e.g.,
less than 10 microns), while also minimizing the amount of very
large catalyst particles (e.g., greater than 50 microns), which
also can be problematic, as discussed further below.
[0035] Herein, the catalyst composition contains at least one
metallocene compound, a solid activator, and typically a
co-catalyst. The solid activator (and the supported metallocene
catalyst) would have the described particle size distribution.
Unlike many available catalyst systems, the disclosed catalyst
system does not use an inert support like silica, nor are MAO and
other similar activators needed in the catalyst system.
[0036] While not wishing to be bound by theory, it is believed that
many of the gels resulting from dual metallocene-based bimodal
polymers are due to the large difference in viscosity that can
arise between the flow characteristics of the polymer fraction
produced from one catalyst and the flow characteristics of the
polymer fraction produced from the other catalyst. It was found
that the particle size of the solid activator (and thus, the
particle size of the supported metallocene catalyst) can impact the
relative amounts of each metallocene compound on the solid
activator. For instance, metallocene compound 1 may react quicker
with the solid activator during catalyst preparation, and thus
preferentially, the smaller activator particles may contain
relatively more metallocene compound 1 and the larger activator
particles may contain relatively more metallocene compound 2. Thus,
in addition to gels, the particle size distribution also can
significantly impact polymer properties, such as polymer molecular
weight distribution and rheological properties in both the low and
high shear regions. For instance, it was found that larger solid
activator particles (and thus larger supported metallocene catalyst
particles) often result in polymer particles with much higher
viscosities and molecular weights than smaller particles.
[0037] By controlling the particle size distribution of the
activator (and the supported metallocene catalyst), more consistent
polymer particle sizes (in powder or fluff form) can be produced,
thereby resulting in ethylene polymers with a unique combination of
density, melt flow, and molecular weight properties, while also
minimizing gels and improving impact strength.
Catalyst Compositions
[0038] Disclosed herein are catalyst compositions comprising a
metallocene compound, a solid activator, and optionally, a
co-catalyst. The solid activator (or the supported metallocene
catalyst) can be characterized by a d50 average particle size in a
range from 15 to 50 .mu.m and a particle size span ((d90-d10)/d50)
in a range from 0.5 to 1.5. Referring first to the solid activator,
which can comprise a solid oxide treated with an
electron-withdrawing anion, examples of such materials are
disclosed in, for instance, U.S. Pat. Nos. 7,294,599, 7,601,665,
7,884,163, 8,309,485, 8,623,973, and 9,023,959, which are
incorporated herein by reference in their entirety. For instance,
the solid activator can comprise fluorided alumina, chlorided
alumina, bromided alumina, sulfated alumina, fluorided
silica-alumina, chlorided silica-alumina, bromided silica-alumina,
sulfated silica-alumina, fluorided silica-zirconia, chlorided
silica-zirconia, bromided silica-zirconia, sulfated
silica-zirconia, fluorided silica-titania, fluorided-chlorided
silica-coated alumina, fluorided silica-coated alumina, sulfated
silica-coated alumina, or phosphated silica-coated alumina, and the
like, as well as any combination thereof.
[0039] In one aspect, the solid activator can comprise fluorided
alumina, sulfated alumina, fluorided silica-alumina, sulfated
silica-alumina, fluorided silica-coated alumina,
fluorided-chlorided silica-coated alumina, sulfated silica-coated
alumina, or any combination thereof. In another aspect, the solid
activator can comprise fluorided alumina; alternatively, sulfated
alumina; alternatively, fluorided silica-alumina; alternatively,
sulfated silica-alumina; alternatively, fluorided silica-coated
alumina; alternatively, fluorided-chlorided silica-coated alumina;
or alternatively, sulfated silica-coated alumina. In yet another
aspect, the solid activator can comprise a fluorided solid oxide
and/or a sulfated solid oxide.
[0040] Various processes can be used to form solid activators
useful in the present invention. Methods of contacting the solid
oxide with the electron-withdrawing component, suitable electron
withdrawing components and addition amounts, impregnation with
metals or metal ions (e.g., zinc, nickel, vanadium, titanium,
silver, copper, gallium, tin, tungsten, molybdenum, zirconium, and
the like, or combinations thereof), and various calcining
procedures and conditions are disclosed in, for example, U.S. Pat.
Nos. 6,107,230, 6,165,929, 6,294,494, 6,300,271, 6,316,553,
6,355,594, 6,376,415, 6,388,017, 6,391,816, 6,395,666, 6,524,987,
6,548,441, 6,548,442, 6,576,583, 6,613,712, 6,632,894, 6,667,274,
6,750,302, 7,294,599, 7,601,665, 7,884,163, and 8,309,485, which
are incorporated herein by reference in their entirety. Other
suitable processes and procedures for preparing solid activators
(e.g., fluorided solid oxides, sulfated solid oxides, etc.) are
well known to those of skill in the art.
[0041] The catalyst composition can contain a co-catalyst. When
present, the co-catalyst can include, but is not limited to, metal
alkyl, or organometal, co-catalysts, with the metal encompassing
boron, aluminum, zinc, and the like. Optionally, the catalyst
systems provided herein can comprise a co-catalyst, or a
combination of co-catalysts. For instance, alkyl boron, alkyl
aluminum, and alkyl zinc compounds often can be used as
co-catalysts in such catalyst systems. Representative boron
compounds can include, but are not limited to, tri-n-butyl borane,
tripropylborane, triethylborane, and the like, and this include
combinations of two or more of these materials. While not being
limited thereto, representative aluminum compounds (e.g.,
organoaluminum compounds) can include trimethylaluminum (TMA),
triethylaluminum (TEA), tri-n-propylaluminum, tri-n-butylaluminum,
triisobutylaluminum (TIBA), tri-n-hexylaluminum,
tri-n-octylaluminum, diisobutylaluminum hydride, diethylaluminum
ethoxide, diethylaluminum chloride, and the like, as well as any
combination thereof. Exemplary zinc compounds (e.g., organozinc
compounds) that can be used as co-catalysts can include, but are
not limited to, dimethylzinc, diethylzinc, dipropylzinc,
dibutylzinc, dineopentylzinc, di(trimethylsilyl)zinc,
di(triethylsilyl)zinc, di(triisopropylsilyl)zinc,
di(triphenylsilyl)zinc, di(allyldimethylsilyl)zinc,
di(trimethylsilylmethyl)zinc, and the like, or combinations
thereof. Accordingly, in an aspect of this invention, the catalyst
composition can comprise the metallocene compound (one or more than
one), the solid activator, and an organoaluminum compound, such as
TMA, TEA, TIBA, and the like, or any combination thereof.
[0042] Consistent with this disclosure, the catalyst composition
can contain a single metallocene compound, for example, any
suitable bridged metallocene compound or any suitable unbridged
metallocene compound, or any bridged metallocene compound or any
unbridged metallocene compound disclosed herein. Alternatively, the
catalyst composition can be a dual catalyst system. In such
instances, the catalyst composition can contain metallocene
component I comprising any suitable unbridged metallocene compound
or any disclosed herein and metallocene component II comprising any
suitable bridged metallocene compound or any disclosed herein.
Whether the catalyst compositions contains a single metallocene
compound, two metallocene compounds, or more than two metallocene
compounds, the catalyst composition also can contain any suitable
solid activator or any solid activator disclosed herein (one or
more than one), and optionally, any suitable co-catalyst or any
co-catalyst disclosed herein (one or more than one).
[0043] Referring first to metallocene component I, which often can
comprise an unbridged zirconium or hafnium based metallocene
compound containing two cyclopentadienyl groups, two indenyl
groups, or a cyclopentadienyl and an indenyl group. In one aspect,
metallocene component I can comprise an unbridged zirconium or
hafnium based metallocene compound containing two cyclopentadienyl
groups. In another aspect, metallocene component I can comprise an
unbridged zirconium or hafnium based metallocene compound
containing two indenyl groups. In yet another aspect, metallocene
component I can comprise an unbridged zirconium or hafnium based
metallocene compound containing a cyclopentadienyl group and an
indenyl group. In still another aspect, metallocene component I can
comprise an unbridged zirconium based metallocene compound
containing an alkyl-substituted cyclopentadienyl group and an
alkenyl-substituted indenyl group.
[0044] Metallocene component I can comprise, in particular aspects
of this invention, an unbridged metallocene compound having formula
(I):
##STR00001##
[0045] Within formula (I), M, Cp.sup.A, Cp.sup.B, and each X are
independent elements of the unbridged metallocene compound.
Accordingly, the unbridged metallocene compound having formula (I)
can be described using any combination of M, Cp.sup.A, Cp.sup.B,
and X disclosed herein. Unless otherwise specified, formula (I)
above, any other structural formulas disclosed herein, and any
metallocene complex, compound, or species disclosed herein are not
designed to show stereochemistry or isomeric positioning of the
different moieties (e.g., these formulas are not intended to
display cis or trans isomers, or R or S diastereoisomers), although
such compounds are contemplated and encompassed by these formulas
and/or structures.
[0046] In accordance with aspects of this invention, the metal in
formula (I), M, can be Zr or Hf. Thus, M can be Zr in one aspect,
and M can be Hf in another aspect. Each X in formula (I)
independently can be a monoanionic ligand. In some aspects,
suitable monoanionic ligands can include, but are not limited to, H
(hydride), BH.sub.4, a halide, a C.sub.1 to C.sub.36 hydrocarbyl
group, a C.sub.1 to C % hydrocarboxy group, a C.sub.1 to C.sub.36
hydrocarbylaminyl group, a C.sub.1 to C.sub.36 hydrocarbylsilyl
group, a C.sub.1 to C.sub.36 hydrocarbylaminylsilyl group,
--OBR.sup.1.sub.2, or --OSO.sub.2R.sup.1, wherein R.sup.1 is a
C.sub.1 to C.sub.36 hydrocarbyl group. It is contemplated that each
X can be either the same or a different monoanionic ligand.
Suitable hydrocarbyl groups, hydrocarboxy groups, hydrocarbylaminyl
groups, hydrocarbylsilyl groups, and hydrocarbylaminylsilyl groups
are disclosed, for example, in U.S. Pat. No. 9,758,600,
incorporated herein by reference in its entirety.
[0047] Generally, the hydrocarbyl group which can be an X in
formula (I) can be a C.sub.1 to C.sub.36 hydrocarbyl group,
including a C.sub.1 to C.sub.36 alkyl group, a C.sub.2 to C.sub.36
alkenyl group, a C.sub.4 to C.sub.36 cycloalkyl group, a C.sub.6 to
C.sub.36 aryl group, or a C.sub.2 to C.sub.6 aralkyl group. For
instance, each X independently can be a C.sub.1 to C.sub.18 alkyl
group, a C.sub.2 to C.sub.18 alkenyl group, a C.sub.4 to C.sub.18
cycloalkyl group, a C.sub.6 to C.sub.18 aryl group, or a C.sub.7 to
C.sub.18 aralkyl group; alternatively, each X independently can be
a C.sub.1 to C.sub.12 alkyl group, a C.sub.2 to C.sub.12 alkenyl
group, a C.sub.4 to C.sub.12 cycloalkyl group, a C.sub.6 to
C.sub.12 aryl group, or a C.sub.7 to C.sub.12 aralkyl group;
alternatively, each X independently can be a C.sub.1 to C.sub.10
alkyl group, a C.sub.2 to C.sub.10 alkenyl group, a C.sub.4 to
C.sub.10 cycloalkyl group, a C.sub.6 to C.sub.10 aryl group, or a
C.sub.7 to C.sub.10 aralkyl group; or alternatively, each X
independently can be a C.sub.1 to C.sub.5 alkyl group, a C.sub.2 to
C.sub.5 alkenyl group, a C.sub.5 to C.sub.8 cycloalkyl group, a
C.sub.6 to C.sub.8 aryl group, or a C.sub.2 to C.sub.5 aralkyl
group.
[0048] In particular aspects of this invention, each X
independently can be a halide or a C.sub.1 to C.sub.18 hydrocarbyl
group. For instance, each X can be Cl.
[0049] In formula (I), Cp.sup.A and Cp.sup.B independently can be a
substituted or unsubstituted cyclopentadienyl or indenyl group. In
one aspect, Cp.sup.A and Cp.sup.B independently can be an
unsubstituted cyclopentadienyl or indenyl group. Alternatively,
Cp.sup.A and Cp.sup.B independently can be a substituted indenyl or
cyclopentadienyl group, for example, having up to 5
substituents.
[0050] If present, each substituent on Cp.sup.A and Cp.sup.B
independently can be H, a halide, a C.sub.1 to C.sub.36 hydrocarbyl
group, a C.sub.1 to C.sub.36 halogenated hydrocarbyl group, a
C.sub.1 to C.sub.36 hydrocarboxy group, or a C.sub.1 to C.sub.36
hydrocarbylsilyl group. Importantly, each substituent on Cp.sup.A
and/or Cp.sup.B can be either the same or a different substituent
group. Moreover, each substituent can be at any position on the
respective cyclopentadienyl or indenyl ring structure that conforms
with the rules of chemical valence. In an aspect, the number of
substituents on Cp.sup.A and/or on Cp.sup.B and/or the positions of
each substituent on Cp.sup.A and/or on Cp.sup.B are independent of
each other. For instance, two or more substituents on Cp.sup.A can
be different, or alternatively, each substituent on Cp.sup.A can be
the same. Additionally or alternatively, two or more substituents
on Cp.sup.B can be different, or alternatively, all substituents on
Cp.sup.B can be the same. In another aspect, one or more of the
substituents on Cp.sup.A can be different from the one or more of
the substituents on Cp.sup.B, or alternatively, all substituents on
both Cp.sup.A and/or on Cp.sup.B can be the same. In these and
other aspects, each substituent can be at any position on the
respective cyclopentadienyl or indenyl ring structure. If
substituted, Cp.sup.A and/or Cp.sup.B independently can have one
substituent, or two substituents, or three substituents, or four
substituents, and so forth.
[0051] Suitable hydrocarbyl groups, halogenated hydrocarbyl groups,
hydrocarboxy groups, and hydrocarbylsilyl groups that can be
substituents are disclosed, for example, in U.S. Pat. No.
9,758,600, incorporated herein by reference in its entirety. For
instance, the halogenated hydrocarbyl group indicates the presence
of one or more halogen atoms replacing an equivalent number of
hydrogen atoms in the hydrocarbyl group. The halogenated
hydrocarbyl group often can be a halogenated alkyl group, a
halogenated alkenyl group, a halogenated cycloalkyl group, a
halogenated aryl group, or a halogenated aralkyl group.
Representative and non-limiting halogenated hydrocarbyl groups
include pentafluorophenyl, trifluoromethyl (CF.sub.3), and the
like.
[0052] Illustrative and non-limiting examples of unbridged
metallocene compounds having formula (I) and/or suitable for use as
metallocene component I can include the following compounds
(Ph=phenyl):
##STR00002## ##STR00003##
and the like, as well as combinations thereof.
[0053] Metallocene component I is not limited solely to unbridged
metallocene compounds such as described above. Other suitable
unbridged metallocene compounds are disclosed in U.S. Pat. Nos.
7,199,073, 7,226,886, 7,312,283, and 7,619,047, which are
incorporated herein by reference in their entirety.
[0054] Referring now to metallocene component II, which can be a
bridged metallocene compound. In one aspect, for instance,
metallocene component II can comprise a bridged zirconium or
hafnium based metallocene compound. In another aspect, metallocene
component II can comprise a bridged zirconium or hafnium based
metallocene compound with an alkenyl substituent. In yet another
aspect, metallocene component II can comprise a bridged zirconium
or hafnium based metallocene compound with an alkenyl substituent
and a fluorenyl group. In still another aspect, metallocene
component II can comprise a bridged zirconium or hafnium based
metallocene compound with a cyclopentadienyl group and a fluorenyl
group, and with an alkenyl substituent on the bridging group and/or
on the cyclopentadienyl group. Further, metallocene component II
can comprise a bridged metallocene compound having an aryl group
substituent on the bridging group.
[0055] Metallocene component 11 can comprise, in particular aspects
of this invention, a bridged metallocene compound having formula
(II):
##STR00004##
[0056] Within formula (II), M, Cp, R.sup.X, R.sup.Y, E, and each X
are independent elements of the bridged metallocene compound.
Accordingly, the bridged metallocene compound having formula (II)
can be described using any combination of M, Cp, R.sup.X, R.sup.Y,
E, and X disclosed herein. The selections for M and each X in
formula (II) are the same as those described herein above for
formula (I). In formula (II), Cp can be a substituted
cyclopentadienyl, indenyl, or fluorenyl group. In one aspect. Cp
can be a substituted cyclopentadienyl group, while in another
aspect. Cp can be a substituted indenyl group.
[0057] In some aspects, Cp can contain no additional substituents,
e.g., other than bridging group E, discussed further herein below.
In other aspects, Cp can be further substituted with one
substituent, or two substituents, or three substituents, or four
substituents, and so forth. If present, each substituent on Cp
independently can be H, a halide, a C.sub.1 to C.sub.36 hydrocarbyl
group, a C.sub.1 to C.sub.36 halogenated hydrocarbyl group, a
C.sub.1 to C.sub.36 hydrocarboxy group, or a C.sub.1 to C.sub.36
hydrocarbylsilyl group. Importantly, each substituent on Cp can be
either the same or a different substituent group. Moreover, each
substituent can be at any position on the respective
cyclopentadienyl, indenyl, or fluorenyl ring structure that
conforms with the rules of chemical valence. In general, any
substituent on Cp, independently, can be H or any halide, C.sub.1
to C.sub.36 hydrocarbyl group, C.sub.1 to C.sub.36 halogenated
hydrocarbyl group, C.sub.1 to C.sub.36 hydrocarboxy group, or
C.sub.1 to C.sub.36 hydrocarbylsilyl group described herein (e.g.,
as pertaining to substituents on Cp.sup.A and Cp.sup.B in formula
(I)).
[0058] Similarly, R.sup.X and R.sup.Y in formula (II) independently
can be H or any halide, C.sub.1 to C.sub.36 hydrocarbyl group,
C.sub.1 to C.sub.36 halogenated hydrocarbyl group, C.sub.1 to
C.sub.36 hydrocarboxy group, or C.sub.1 to C.sub.36
hydrocarbylsilyl group disclosed herein (e.g., as pertaining to
substituents on Cp.sup.A and Cp.sup.B in formula (I)). In one
aspect, for example, R.sup.X and R.sup.Y independently can be H or
a C.sub.1 to C.sub.12 hydrocarbyl group. In another aspect, R.sup.X
and R.sup.Y independently can be a C.sub.1 to C.sub.10 hydrocarbyl
group. In yet another aspect, R.sup.X and R.sup.Y independently can
be H, Cl, CF.sub.3, a methyl group, an ethyl group, a propyl group,
a butyl group (e.g., t-Bu), a pentyl group, a hexyl group, a heptyl
group, an octyl group, a nonyl group, a decyl group, an ethenyl
group, a propenyl group, a butenyl group, a pentenyl group, a
hexenyl group, a heptenyl group, an octenyl group, a nonenyl group,
a decenyl group, a phenyl group, a tolyl group, a benzyl group, a
naphthyl group, a trimethylsilyl group, a triisopropylsilyl group,
a triphenylsilyl group, or an allyldimethylsilyl group, and the
like. In still another aspect, R.sup.X and R.sup.Y independently
can be a methyl group, an ethyl group, a propyl group, a butyl
group, a pentyl group, a hexyl group, a heptyl group, an octyl
group, a nonyl group, a decyl group, an ethenyl group, a propenyl
group, a butenyl group, a pentenyl group, a hexenyl group, a
heptenyl group, an octenyl group, a nonenyl group, a decenyl group,
a phenyl group, a tolyl group, or a benzyl group.
[0059] Bridging group E in formula (II) can be a bridging group
having the formula >E.sup.AR.sup.AR.sup.B, wherein E.sup.A can
be C, Si, or Ge, and R.sup.A and R.sup.B independently can be H or
a C.sub.1 to C.sub.18 hydrocarbyl group. In some aspects of this
invention, R.sup.A and R.sup.B independently can be a C.sub.1 to
C.sub.12 hydrocarbyl group; alternatively, R.sup.A and R.sup.B
independently can be a C.sub.1 to C.sub.8 hydrocarbyl group;
alternatively, R.sup.A and R.sup.B independently can be a phenyl
group, a C.sub.1 to C.sub.8 alkyl group, or a C.sub.3 to C.sub.8
alkenyl group; alternatively, R.sup.A and R.sup.B independently can
be a methyl group, an ethyl group, a propyl group, a butyl group, a
pentyl group, a hexyl group, a heptyl group, an octyl group, a
nonyl group, a decyl group, an ethenyl group, a propenyl group, a
butenyl group, a pentenyl group, a hexenyl group, a heptenyl group,
an octenyl group, a nonenyl group, a decenyl group, a phenyl group,
a cyclohexylphenyl group, a naphthyl group, a tolyl group, or a
benzyl group; or alternatively, R.sup.A and R.sup.B independently
can be a methyl group, an ethyl group, a propyl group, a butyl
group, a pentyl group, a hexyl group, a propenyl group, a butenyl
group, a pentenyl group, a hexenyl group, a phenyl group, or a
benzyl group. In these and other aspects, R.sup.A and R.sup.B can
be either the same or different.
[0060] Illustrative and non-limiting examples of bridged
metallocene compounds having formula (II) and/or suitable for use
as metallocene component II can include the following compounds
(Me=methyl, Ph=phenyl; t-Bu=tert-butyl):
##STR00005## ##STR00006##
and the like, as well as combinations thereof.
[0061] Metallocene component II is not limited solely to the
bridged metallocene compounds such as described above. Other
suitable bridged metallocene compounds are disclosed in U.S. Pat.
Nos. 7,026,494, 7,041,617, 7,226,886, 7,312,283, 7,517,939, and
7,619,047, which are incorporated herein by reference in their
entirety.
[0062] According to an aspect of this invention, the weight ratio
of metallocene component I to metallocene component II in the
catalyst composition can be in a range from 10:1 to 1:10, from 8:1
to 1:8, from 5:1 to 1:5, from 4:1 to 1:4, from 3:1 to 1:3; from 2:1
to 1:2, from 1.5:1 to 1:1.5, from 1.25:1 to 1:1.25, or from 1.1:1
to 1:1.1. In another aspect, metallocene component I is the major
component of the catalyst composition, and in such aspects, the
weight ratio of metallocene component I to metallocene component II
in the catalyst composition can be in a range from 10:1 to 1:1,
from 5:1 to 1.1:1, from 2:1 to 1.1:1, or from 1.8:1 to 1.1:1.
[0063] It is contemplated herein that the catalyst composition can
comprise a metallocene compound (or metallocene component I and
metallocene component II), a solid activator, and a co-catalyst
(e.g., an organoaluminum compound), wherein this catalyst
composition is substantially free of aluminoxanes, organoboron or
organoborate compounds, ionizing ionic compounds, and/or other
similar materials; alternatively, substantially free of
aluminoxanes, alternatively, substantially free or organoboron or
organoborate compounds; or alternatively, substantially free of
ionizing ionic compounds. In these aspects, the catalyst
composition has catalyst activity, discussed herein, in the absence
of these additional materials. For example, a catalyst composition
of the present invention can consist essentially of the metallocene
compound (or metallocene component I and metallocene component II),
the solid activator, and the organoaluminum compound, wherein no
other materials are present in the catalyst composition which would
increase/decrease the activity of the catalyst composition by more
than 10% from the catalyst activity of the catalyst composition in
the absence of said materials.
[0064] Catalyst compositions of the present invention generally
have a catalyst activity greater than 150 grams of ethylene polymer
(homopolymer and/or copolymer, as the context requires) per gram of
solid activator per hour (abbreviated g/g/hr). In another aspect,
the catalyst activity can be greater than 250, greater than 350, or
greater than 500 g/g/hr. Yet, in another aspect, the catalyst
activity can be greater than 700 g/g/hr, greater than 1000 g/g/hr,
or greater than 2000 g/g/hr. and often as high as 5000-10,000
g/g/hr. Illustrative and non-limiting ranges for the catalyst
activity include from 150 to 10,000, from 500 to 7500, or from 1000
to 5000 g/g/hr, and the like. These activities are measured under
slurry polymerization conditions, with a triisobutylaluminum
co-catalyst, using isobutane as the diluent, at a polymerization
temperature of 95.degree. C. and a reactor pressure of 590 psig.
Moreover, in some aspects, the solid activator comprise sulfated
alumina, fluorided silica-alumina, or fluorided silica-coated
alumina, although not limited thereto.
[0065] This invention further encompasses methods of making these
catalyst compositions, such as, for example, contacting the
respective catalyst components in any order or sequence. In one
aspect, for example, the catalyst composition can be produced by a
process comprising contacting, in any order, the metallocene
compound, the solid activator, and the co-catalyst, while in
another aspect, the catalyst composition can be produced by a
process comprising contacting, in any order, metallocene component
I, metallocene component II, the solid activator, and the
co-catalyst.
[0066] In the catalyst compositions disclosed herein, the solid
activator (or the supported metallocene catalyst) can be
characterized by a d50 average particle size in a range from 15 to
50 .mu.m and a particle size span ((d90-d10)/d50) in a range from
0.5 to 1.5. In one aspect, the d50 average particle size can be in
a range from 15 to 40 .mu.m or from 15 to 25 .mu.m, while in
another aspect, the d50 particle size can be from 20 to 30 .mu.m,
and in another aspect, the d50 particle size can be from 17 to 40
.mu.m or from 17 to 27 .mu.m, and in still another aspect, the d50
particle size can be from 17 to 25 .mu.m. Likewise, the span
((d90-d10)/d50) can be in a range from 0.5 to 1.2 in one aspect,
from 0.6 to 1.4 or from 0.6 to 1.3 in another aspect, from 0.6 to
1.1 in yet another aspect, and from 0.7 to 1.4 or from 0.7 to 1.2
in still another aspect. The solid activator (or the supported
metallocene catalyst) also can have any of the particle attributes
listed below and in any combination, unless indicated
otherwise.
[0067] The solid activator (or the supported metallocene catalyst)
can have a d10 particle size of greater than or equal to 10 .mu.m;
alternatively, greater than or equal to 11 .mu.m; alternatively,
greater than or equal to 12 .mu.m; alternatively, in a range from
10 to 20 .mu.m; or alternatively in a range from 10 to 18 .mu.m.
Additionally or alternatively, the solid activator (or the
supported metallocene catalyst) can have a d95 particle size of
less than or equal to 65 .mu.m; alternatively, less than or equal
to 60 .mu.m; alternatively, in a range from 25 to 65 .mu.m; or
alternatively, in a range from 28 to 60 .mu.m.
[0068] While not limited thereto, the solid activator (or the
supported metallocene catalyst) can be further characterized by a
ratio of d90/d10, which often ranges from 1.5 to 5. In some
aspects, the ratio of d90/d10 can be from 1.5 to 4, from 1.5 to 3,
from 1.8 to 5, from 1.8 to 4, or from 1.8 to 3.
[0069] Typically, a very small amount of the solid activator (or
the supported metallocene catalyst) has a particle size of less
than 10 .mu.m. In one aspect, the amount is less than or equal to
15% or less than or equal to 10%, while in another aspect, the
amount is less than or equal to 8% or less than or equal to 5%, and
in yet another aspect, the amount is less than or equal to 2%.
Likewise, a very small amount of the solid activator (or the
supported metallocene catalyst) has a particle size of greater than
45 .mu.m. In one aspect, the amount is less than or equal to 20%,
while in another aspect, the amount is less than or equal to 15% or
less than or equal to 10%, and in yet another aspect, the amount is
less than or equal to 5% or less than or equal to 2%. In contrast,
a vast majority of the solid activator (or the supported
metallocene catalyst) has a particle size of less than 50 .mu.m.
For instance, at least 85% of the solid activator (or the supported
metallocene catalyst) has a particle size of less than 50 .mu.m,
while in further aspects, the amount of the solid activator (or the
supported metallocene catalyst) with a particle size of less than
50 .mu.m can be at least 88%, at least 90%, or at least 95%.
Polymerization Processes
[0070] Olefin polymers (e.g., ethylene polymers) can be produced
from the disclosed metallocene catalyst compositions using any
suitable polymerization process using various types of
polymerization reactors, polymerization reactor systems, and
polymerization reaction conditions. A polymerization process can
comprise contacting the catalyst composition (any metallocene-based
catalyst composition disclosed herein) with an olefin monomer and
an optional olefin comonomer in a polymerization reactor system
comprising a loop slurry reactor under polymerization conditions to
produce an olefin polymer. This invention also encompasses any
olefin polymers (e.g., ethylene polymers) produced by the
polymerization processes disclosed herein.
[0071] In one aspect, the polymerization reactor system can
comprise only one loop slurry reactor (a single loop slurry
reactor). However, in another aspect, the polymerization reactor
system can comprise two or more reactors, at least one of which is
the loop slurry reactor. The other reactor(s) in the polymerization
reactor system can be another slurry reactor (dual loop slurry), a
gas-phase reactor, a solution reactor, or a combination thereof.
The production of polymers in multiple reactors can include several
stages in at least two separate polymerization reactors
interconnected by a transfer device making it possible to transfer
the polymers resulting from the first polymerization reactor into
the second reactor. The desired polymerization conditions in one of
the reactors can be different from the operating conditions of the
other reactor(s). Alternatively, polymerization in multiple
reactors can include the manual transfer of polymer from one
reactor to subsequent reactors for continued polymerization. The
multiple reactors can be operated in series, in parallel, or both.
Accordingly, the present invention encompasses polymerization
reactor systems comprising a single reactor, comprising two
reactors, and comprising more than two reactors, wherein at least
one is a loop slurry reactor.
[0072] In a loop slurry reactor, monomer, diluent, catalyst system,
and comonomer (if used) can be continuously fed to a loop reactor
where polymerization occurs. Generally, continuous processes can
comprise the continuous introduction of monomer/comonomer, a
catalyst system, and a diluent into a polymerization reactor and
the continuous removal from this reactor of a suspension comprising
polymer particles (powder or fluff) and the diluent. Reactor
effluent can be flashed to remove the solid polymer from the
liquids that comprise the diluent, monomer and/or comonomer.
Various technologies can be used for this separation step
including, but not limited to, flashing that can include any
combination of heat addition and pressure reduction, separation by
cyclonic action in either a cyclone or hydrocyclone, or separation
by centrifugation.
[0073] A typical slurry polymerization process (also known as the
particle form process) is disclosed, for example, in U.S. Pat. Nos.
3,248,179, 4,501,885, 5,565.175, 5,575,979, 6,239,235, 6,262,191,
6,833,415, and 8,822,608, each of which is incorporated herein by
reference in its entirety.
[0074] Suitable diluents used in slurry polymerization include, but
are not limited to, the monomer being polymerized and hydrocarbons
that are liquids under reaction conditions. Examples of suitable
diluents include, but are not limited to, hydrocarbons such as
propane, cyclohexane, isobutane, n-butane, n-pentane, isopentane,
neopentane, and n-hexane. Some loop polymerization reactions can
occur under bulk conditions where no diluent is used.
[0075] The polymerization reactor system can further comprise any
combination of at least one raw material feed system, at least one
feed system for the catalyst system or catalyst components, and/or
at least one polymer recovery system. Suitable reactor systems can
further comprise systems for feedstock purification, catalyst
storage and preparation, extrusion, reactor cooling, polymer
recovery, fractionation, recycle, storage, loadout, laboratory
analysis, and process control. Depending upon the desired
properties of the olefin polymer, hydrogen can be added to the
polymerization reactor system as needed (e.g., continuously,
pulsed, etc.).
[0076] Polymerization conditions that can be controlled for
efficiency and to provide desired polymer properties can include
temperature, pressure, and the concentrations of various reactants.
Polymerization temperature can affect catalyst productivity,
polymer molecular weight, and molecular weight distribution.
Various polymerization conditions can be held substantially
constant, for example, for the production of a particular grade of
the olefin polymer (or ethylene polymer). A suitable polymerization
temperature can be any temperature below the de-polymerization
temperature according to the Gibbs Free energy equation. Typically,
this includes from 60.degree. C. to 280.degree. C., for example, or
from 60.degree. C. to 120.degree. C., depending upon the type of
polymerization reactor. In some loop reactor systems, the
polymerization temperature generally can be within a range from
70.degree. C. to 100.degree. C., or from 75.degree. C. to
95.degree. C. Suitable pressures will also vary according to the
reactor and polymerization type. The pressure for liquid phase
polymerizations in a loop reactor is typically less than 1000 psig
(6.9 MPa) and greater than 200 psig (1.4 MPa).
[0077] Olefin monomers that can be employed with the catalyst
compositions and slurry-based polymerization processes of this
invention typically can include olefin compounds having from 2 to
30 carbon atoms per molecule and having at least one olefinic
double bond, such as ethylene or propylene. In an aspect, the
olefin monomer can comprise a C.sub.2-C.sub.20 olefin;
alternatively, a C.sub.2-C.sub.20 alpha-olefin; alternatively, a
C.sub.2-C.sub.10 olefin; alternatively, a C.sub.2-C.sub.10
alpha-olefin; alternatively, the olefin monomer can comprise
ethylene; or alternatively, the olefin monomer can comprise
propylene (e.g., to produce a polypropylene homopolymer or a
propylene-based copolymer).
[0078] When a copolymer (or alternatively, a terpolymer) is
desired, the olefin monomer and the olefin comonomer independently
can comprise, for example, a C.sub.2-C.sub.20 alpha-olefin. In some
aspects, the olefin monomer can comprise ethylene or propylene,
which is copolymerized with at least one comonomer (e.g., a
C.sub.2-C.sub.20 alpha-olefin, a C.sub.3-C.sub.20 alpha-olefin,
etc.). According to one aspect of this invention, the olefin
monomer used in the polymerization process can comprise ethylene.
In this aspect, the comonomer can comprise a C.sub.3-C.sub.10
alpha-olefin; alternatively, the comonomer can comprise 1-butene,
1-pentene, 1-hexene, 1-octene, 1-decene, styrene, or any
combination thereof; alternatively, the comonomer can comprise
1-butene, 1-hexene, 1-octene, or any combination thereof;
alternatively, the comonomer can comprise 1-butene; alternatively,
the comonomer can comprise 1-hexene; or alternatively, the
comonomer can comprise 1-octene.
[0079] An illustrative and non-limiting example of an ethylene
polymer composition that can be produced using the catalysts and
processes disclosed herein can have a d50 average particle size in
a range from 150 to 600 .mu.m, a particle size span ((d90-d10)/d50)
in a range from 0.5 to 1.6, less than or equal to 20% of the
composition with a particle size of less than 100 .mu.m, and less
than or equal to 5% of the composition with a particle size of
greater than 1000 .mu.m. The ethylene polymer composition can be in
powder form (also referred to as fluff), prior to mixing and
homogenizing to form typical resin pellets or beads.
[0080] Often, the d50 average particle size can fall within a range
from 150 to 450 .mu.m, from 150 to 325 .mu.m, from 150 to 300
.mu.m, from 175 to 325 .mu.m, from 175 to 275 .mu.m, from 200 to
400 .mu.m, or from 200 to 275 .mu.m, and the span ((d90-d10)/d50)
can fall within a range from 0.75 to 1.5, from 1 to 1.6, from 1.1
to 1.6, or from 1.1 to 1.5. Additionally or alternatively, the
amount of the composition having a particle size of greater than
1000 .mu.m can be less than or equal to 5%, such as less than or
equal to 3%, less than or equal to 2%, or less than or equal to 1%.
Additionally or alternatively, the amount of the composition having
a particle size of less than 100 .mu.m can be less than or equal to
20%, such as less than or equal to 10%, less than or equal to 5%,
from 1 to 10%, or from 1 to 5%.
[0081] Optionally, the ethylene polymer composition (in powder or
fluff form) can be further characterized by a d90 particle size
from 300 to 800 .mu.m (e.g., from 300 to 600 .mu.m, from 350 to 550
.mu.m, from 375 to 525 .mu.m, from 400 to 750 .mu.m, or from 400 to
500 .mu.m) and/or by a ratio of d90/d10 from 2 to 5 (e.g., from 2
to 4, from 2.2 to 3.8, from 2.4 to 5, from 2.4 to 3.6, or from 2.7
to 3.3).
[0082] While not limited thereto, the HLMI of the composition can
be in a range from 4 to 10 g/10 min; alternatively, from 4 to 9
g/10 min; alternatively, from 4 to 8 g/10 min; alternatively, from
5 to 10 g/10 min; alternatively, from 5 to 9 g/10 min; or
alternatively, from 5 to 8 g/10 min. Likewise, the density of the
composition is not particularly limited, generally ranging from
0.944 to 0.955 g/cm.sup.3, and additional illustrative ranges
include from 0.944 to 0.952, from 0.945 to 0.955, from 0.945 to
0.953, from 0.945 to 0.95, from 0.946 to 0.955, or from 0.946 to
0.952 g/cm.sup.3, and the like.
[0083] It should be noted that the metallocene-based catalysts
produced by the solid activators of this invention tend to produce
a more homogeneous distribution of polymer particles, in terms of
size and also in terms of comonomer incorporation. The narrow
distribution of polymer particle size significantly helps the flow
of the polymer powder, reducing fouling, packing, and enhancing
transfer in downstream operations. This is partly because the
polymer powder has less tendency to segregate upon handling. In
segregation test ASTM 6941, this results in less than 10%, and in
some cases, less than 7%, less than 5% or less than 3% change in
the mean size in samples taken from the top to the bottom of the
settled polymer bed. Similarly, the change in d10 value from top to
bottom is less than 20%, and more often can be less than 15%, less
than 10%, or less than 7%. Likewise, the change in d90 value can be
less than 5%; alternatively, less than 3%; or alternatively, less
than 2%.
[0084] The coefficient of variation in the segregation test for the
mean should be less than 7%, and can be less than 6%, less than 5%,
less than 4%, or less than 3%, in some aspects. For the d10 value,
it should be less than 25%, and can be less 20%, less than 15%,
less than 10%, or less than 7%, in some aspects. For the d90, the
coefficient of variation should be less than 5%, and can be less
than 4%, or less than 3%, in some aspects. Further, for the d50
value, the coefficient of variation should be less than 8%, and can
be less than 7%, less than 6%, less than 5%, less than 4%, or less
than 3%, in some aspects.
[0085] Another consequence of polymer particle heterogeneity is
that the density of each particle can vary widely. However, the
polymer particles (also referred to as powder or fluff) of this
invention vary less than 0.035 g/cm.sup.3 in one aspect, less than
0.03 g/cm.sup.3 in another aspect, less than 0.02 g/cm.sup.3 in
another aspect, less than 0.015 g/cm.sup.3 in another aspect, less
than 0.01 g/cm.sup.3 in yet another aspect, or less than 0.006
g/cm.sup.3 in still another aspect.
Olefin Polymers
[0086] This invention is also directed to, and encompasses, the
olefin polymers produced by any of the polymerization processes
disclosed herein. Olefin polymers encompassed herein can include
any polymer produced from any olefin monomer and optional
comonomer(s) described herein. For example, the olefin polymer can
comprise an ethylene homopolymer, an ethylene copolymer (e.g.,
ethylene/.alpha.-olefin, ethylene/1-butene, ethylene/1-hexene,
ethylene/1-octene, etc.), a propylene homopolymer, a propylene
copolymer, an ethylene terpolymer, a propylene terpolymer, and the
like, including any combinations thereof. In one aspect, the olefin
polymer can comprise an ethylene homopolymer, an ethylene/1-butene
copolymer, an ethylene/1-hexene copolymer, and/or an
ethylene/1-octene copolymer, while in another aspect, the olefin
polymer can comprise an ethylene/1-hexene copolymer.
[0087] If the resultant polymer produced in accordance with the
present invention is, for example, an ethylene polymer, its
properties can be characterized by various analytical techniques
known and used in the polyolefin industry. Articles of manufacture
can be formed from, and/or can comprise, the olefin polymers (e.g.,
ethylene polymers) of this invention, whose typical properties are
provided below.
[0088] The densities of ethylene-based polymers disclosed herein
often are greater than or equal to 0.90 g/cm.sup.3, and less than
or equal to 0.97 g/cm.sup.3. Yet, in particular aspects, the
density can be in a range from 0.91 to 0.965 g/cm.sup.3, from 0.92
to 0.96 g/cm.sup.3, from 0.93 to 0.955 g/cm.sup.3, or from 0.94 to
0.955 g/cm.sup.3. While not being limited thereto, the ethylene
polymer can have a high load melt index (HLMI) in a range from 0 to
100 g/10 min; alternatively, from 1 to 80 g/10 min; alternatively,
from 2 to 40 g/10 min; alternatively, from 2 to 30 g/10 min;
alternatively, from 1 to 20 g/10 min; or alternatively, from 50 to
100 g/10 min. In an aspect, ethylene polymers described herein can
have a ratio of Mw/Mn, or the polydispersity index, in a range from
2 to 40, from 5 to 40, from 7 to 25, from 8 to 15, from 2 to 10,
from 2 to 6, or from 2 to 4. Additionally or alternatively, the
ethylene polymer can have a weight-average molecular weight (Mw) in
a range from 75,000 to 700,000, from 75,000 to 200,000, from
100,000 to 500,000, from 150,000 to 350,000, or from 200,000 to
320,000 g/mol. Moreover, the olefin polymers can be produced with a
single or dual metallocene catalyst system containing zirconium
and/or hafnium. In such instances, the olefin or ethylene polymer
can contain no measurable amount of Mg, V, Ti, and Cr, i.e., less
than 0.1 ppm by weight. In further aspects, the olefin or ethylene
polymer can contain, independently, less than 0.08 ppm, less than
0.05 ppm, or less than 0.03 ppm, of Mg, V, Ti, and Cr.
[0089] It was surprisingly found that the particular size
distribution of the solid activator (and thus, the particle size
distribution of the supported metallocene catalyst, for instance,
containing two metallocene compounds) significantly impacts the
molecular weight and rheological properties of the resulting
ethylene polymer. For instance, it was found that larger solid
activator particles (and thus larger supported metallocene catalyst
particles) often result in polymer particles with higher
viscosities and higher molecular weights than smaller particles,
and further, these can often lead to gels due to their high
viscosity and poor dispersibility.
[0090] An illustrative and non-limiting example of a particular
ethylene polymer (e.g., an ethylene/.alpha.-olefin
copolymer)--produced using the solid activator with a d50 from 15
to 50 .mu.m and a particle size distribution from 0.5 to 1.5--has a
high load melt index (HLMI) in a range from 4 to 10 g/10 min, a
density in a range from 0.944 to 0.955 g/cm.sup.3, and a higher
molecular weight component and a lower molecular weight component.
The higher molecular weight component can have a Mn in a range from
280,000 to 440,000 g/mol, while the lower molecular weight
component can have a Mw in a range from 30,000 to 45,000 g/mol, and
a ratio of Mz/Mw in a range from 2.3 to 3.4. While not limited
thereto, the ethylene polymer can be in the form of pellets or
beads. This illustrative and non-limiting example of a particular
ethylene polymer consistent with the present invention also can
have any of the polymer properties listed below and in any
combination, unless indicated otherwise.
[0091] The ethylene polymer can comprise a high or higher molecular
weight (HMW) component (or a first component) and a low or lower
molecular weight (LMW) component (or a second component). These
component terms are relative, are used in reference to each other,
and are not limited to the actual molecular weights of the
respective components. The molecular weight characteristics of
these LMW and HMW components are determined by deconvoluting the
composite (overall polymer) molecular weight distribution (e.g.,
determined using gel permeation chromatography). The amount of the
lower molecular weight (LMW) component, based on the total polymer,
is not limited to any particular range. Generally, however, the
amount of the lower molecular weight component can be in a range
from 56 to 72 wt. %, from 56 to 70 wt. %, from 58 to 72 wt. %, from
58 to 70 wt. %, or from 60 to 68 wt. %.
[0092] The higher molecular weight component can have a Mn in a
range from 280,000 to 440,000 g/mol. For instance, the Mn can fall
within a range from 280,000 to 425,000; alternatively, from 280.000
to 400,000; alternatively, from 290,000 to 410,000; alternatively,
from 300,000 to 440.000, or alternatively, from 300,000 to 400,000
g/mol. Additionally or alternatively, the higher molecular weight
component can have a relatively narrow molecular weight
distribution, which can be quantified by a ratio of Mw/Mn in from
1.6 to 2.4 in one aspect, from 1.7 to 2.4 (or from 1.7 to 2.3) in
another aspect, from 1.8 to 2.4 (or from 1.8 to 2.3) in yet another
aspect, or from 1.9 to 2.4 (or from 1.9 to 2.3) in still another
aspect. Additionally or alternatively, the higher molecular weight
component can have a Mz in a range from 900.000 to 1,600,000 g/mol,
although not limited thereto. Typical ranges for the Mz of the
higher molecular weight component can include, but are not limited
to, from 1,000,000 to 1,500,000, from 1,000,000 to 1,400,000, from
1,100,00) to 1,600,000, or from 1,100,000 to 1,500,000 g/mol.
[0093] The lower molecular weight component of the ethylene polymer
can have a Mw in a range from 30,000 to 45,000 g/mol (or from
30,000 to 43,000, or from 30,000 to 41,000, or from 31,000 to
45,000, or from 31,000 to 42,000, or from 31.000 to 40,000, or from
32,000 to 44,000, or from 32,000 to 42,000 g/mol), and a ratio of
Mz/Mw in a range from 2.3 to 3.4 (or from 2.3 to 3.2, or from 2.35
to 3.0, or from 2.4 to 3.3, or from 2.4 to 3.2, or from 2.4 to
3.1). Additionally or alternatively, the lower molecular weight
component can have a Mn that falls within a range from 4,000 to
10,000 g/mol, such as from 4,000 to 9,000, from 5,000 to 10,000,
from 5,000 to 9,000, or from 5,500 to 8,500 g/mol. Additionally or
alternatively, the lower molecular weight component can have a Mz
that falls within a range from 70.000 to 130.000 g/mol, such as
from 70,000 to 115,000, from 75,000 to 130,000, from 75,000 to
120.000, or from 75,000 to 115,000 g/mol.
[0094] The density of the ethylene-based polymer can range from
0.944 to 0.955 g/cm.sup.3. In one aspect, the density can range
from 0.944 to 0.952, from 0.945 to 0.955 in another aspect, from
0.945 to 0.953 in another aspect, from 0.945 to 0.95 in another
aspect, from 0.946 to 0.955 in yet another aspect, or from 0.946 to
0.952 g/cm.sup.3 in still another aspect.
[0095] The ethylene polymer has a very low melt index, as indicated
by the high load melt index (HLMI) in a range from 4 to 10 g/10
min. In some aspects, the HLMI of the ethylene polymer can fall
within a range from 4 to 9 or from 4 to 8 g/10 min. In other
aspects, the HLMI of the ethylene polymer can fall within a range
from 5 to 10, from 5 to 9, or from 5 to 8 g/10 min.
[0096] In an aspect, the ethylene polymer (inclusive of the higher
and lower molecular weight components) can have a Mw in a range
from 230,000 to 330,000, from 230,000 to 320,000, from 240,000 to
330,000, or from 240,000 to 320,000 g/mol. The ethylene polymer has
a relatively broad molecular weight distribution, often with a
ratio of Mw/Mn in a range from 20 to 45. For instance, the ratio of
Mw/Mn of the polymer can be from 20 to 42; alternatively, from 22
to 44; alternatively, from 25 to 45; or alternatively, from 25 to
42.
[0097] The ethylene polymer can have a CY-a parameter of from 0.45
to 0.65, from 0.47 to 0.63, from 0.47 to 0.61, from 0.48 to 0.6,
from 0.5 to 0.65, from 0.5 to 0.63, or from 0.5 to 0.6, and the
like. Additionally or alternatively, the ethylene polymer can have
a relaxation time (Tau(eta) or .tau.(.eta.)) in a range from 1.5 to
4, from 1.5 to 3.7, from 2 to 4, or from 2 to 3.6 sec. Additionally
or alternatively, the ethylene polymer can have a viscosity at 100
sec.sup.-1 (eta @ 100 or .eta. @ 100) at 190.degree. C. in a range
from 2000 to 3600, from 2000 to 3500, from 2100 to 3600, or from
2100 to 3500 Pa-sec. Additionally or alternatively, the ethylene
polymer can have a ratio of viscosity at 0.1 sec.sup.-1 to
viscosity at 100 sec.sup.-1 (.eta. @ 0.1/.eta. @100) in a range
from 38 to 72, from 40 to 68, from 46 to 68, or from 52 to 72, and
the like. These rheological parameters are determined from
viscosity data measured at 190.degree. C. and using the
Carreau-Yasuda (CY) empirical model described herein.
[0098] In an aspect, the ethylene polymer described herein can be a
reactor product (e.g., a single reactor product), for example, not
a post-reactor blend of two polymers, for instance, having
different molecular weight characteristics. As one of skill in the
art would readily recognize, physical blends of two different
polymer resins can be made, but this necessitates additional
processing and complexity not required for a reactor product.
[0099] Moreover, the ethylene polymer can be produced with dual
metallocene catalyst systems containing zirconium and/or hafnium,
as discussed herein. Ziegler-Natta and chromium based catalysts
systems are not required. Therefore, the ethylene polymer can
contain no measurable amount of chromium or titanium or vanadium or
magnesium (catalyst residue), i.e., less than 0.1 ppm by weight. In
some aspects, the ethylene polymer can contain, independently, less
than 0.08 ppm, less than 0.05 ppm, or less than 0.03 ppm, of
chromium (or titanium, or vanadium, or magnesium).
[0100] Consistent with aspects of this disclosure, any olefin
polymer (or ethylene polymer) described herein can have very few
gels, characterized by a film gel count of less than 100 gels per
ft.sup.2 of 25 micron film. In further aspects, the film gel count
can be less than 50, less than 25, less than 10, or less than 5
gels per ft.sup.2 of 25 micron film. Herein, gels encompass any
film defect having a size greater than 200 microns. The gel testing
procedure and equipment are described in the examples that
follow.
Articles and Products
[0101] Articles of manufacture can be formed from, and/or can
comprise, the olefin polymers (e.g., ethylene polymers) of this
invention and, accordingly, are encompassed herein. For example,
articles which can comprise the polymers of this invention can
include, but are not limited to, an agricultural film, an
automobile part, a bottle, a container for chemicals, a drum, a
fiber or fabric, a food packaging film or container, a food service
article, a fuel tank, a geomembrane, a household container, a
liner, a molded product, a medical device or material, an outdoor
storage product (e.g., panels for walls of an outdoor shed),
outdoor play equipment (e.g., kayaks, bases for basketball goals),
a pipe, a sheet or tape, a toy, or a traffic barrier, and the like.
Various processes can be employed to form these articles.
Non-limiting examples of these processes include injection molding,
blow molding, rotational molding, film extrusion, sheet extrusion,
profile extrusion, thermoforming, and the like. Additionally,
additives and modifiers often are added to these polymers in order
to provide beneficial polymer processing or end-use product
attributes. Such processes and materials are described in Modern
Plastics Encyclopedia, Mid-November 1995 Issue, Vol. 72, No. 12;
and Film Extrusion Manual--Process, Materials, Properties. TAPPI
Press, 1992; the disclosures of which are incorporated herein by
reference in their entirety. In some aspects of this invention, an
article of manufacture can comprise any of olefin polymers (or
ethylene polymers) described herein, and the article of manufacture
can be or can comprise a film, such as a blown film.
[0102] Films disclosed herein, whether cast or blown, can be any
thickness that is suitable for the particular end-use application,
and often, the average film thickness can be in a range from 0.25
to 25 mils, or from 0.4 to 20 mils. For certain film applications,
typical average thicknesses can be in a range from 0.5 to 8 mils,
from 0.8 to 5 mils, from 0.7 to 2 mils, or from 0.7 to 1.5
mils.
[0103] In an aspect and unexpectedly, the films (e.g. blown films)
can have excellent dart impact strength, particular in view of the
density of the polymer. As an example, the ethylene polymer with a
HLMI from 4 to 10 g/10 min, a density from 0.944 to 0.955
g/cm.sup.3, a HMW component with a Mn from 280,000 to 440.000
g/mol, and a LMW component with a Mw from 30,000 to 45,000 g/mol
and a ratio of Mz/Mw from 2.3 to 3.4, can have a dart impact
greater than or equal to 150 g/mil, greater than or equal to 200
g/mil, or greater than or equal to 250 g/mil, and often can range
up to 500-750 g/mil or more. For many film applications, the upper
limit on dart impact is not determined, so long as the dart impact
exceeds a particular minimal value or threshold. Nonetheless, the
dart impact values often fall within a range from 150 to 750 g/mil,
from 250 to 600 g/mil, or from 300 to 700 g/mil.
[0104] The film products encompassed herein also can be
characterized by very low levels of gels, typically having a film
gel count of less than 100 gels per ft.sup.2 of 25 micron film, and
more often, the film gel count is less than 50, less than 25, less
than 10, or less than 5 gels per ft.sup.2 of 25 micron film.
Herein, gels encompass any film defect with a size greater than 200
microns.
EXAMPLES
[0105] The invention is further illustrated by the following
examples, which are not to be construed in any way as imposing
limitations to the scope of this invention. Various other aspects,
embodiments, modifications, and equivalents thereof which, after
reading the description herein, may suggest themselves to one of
ordinary skill in the art without departing from the spirit of the
present invention or the scope of the appended claims.
[0106] Melt index (MI, g/10 min) can be determined in accordance
with ASTM D1238 at 190.degree. C. with a 2,160 gram weight, and
high load melt index (HLMI, g/10 min) was determined in accordance
with ASTM D1238 at 190.degree. C. with a 21,600 gram weight.
Density was determined in grams per cubic centimeter (g/cm.sup.3)
on a compression molded sample, cooled at 15.degree. C. per minute,
and conditioned for 40 hours at room temperature in accordance with
ASTM D1505 and ASTM D4703.
[0107] Dart impact strength (g/mil) was measured in accordance with
ASTM D1709 (method A, 26 inches, F50). Blown films were produced
from the ethylene polymers on a high density blown film line having
a 1.5-in diameter Davis-Standard extruder with a L/D of 24:1, and a
2-in diameter Sano die with a 35-mil die gap. Processing conditions
included barrel temperatures of 210-230.degree. C., a screw speed
of 30 rpm, an output rate of 17-18 lb/hr, a film thickness of 1
mil, a 4.1 blow-up ratio, a line speed of 65 ft/min, a frostline
height of 14 in, and a layflat width of 12.5 in.
[0108] Gels were measured on 25 .mu.m (1 mil) film, using an
automated camera-based gel counting machine made by Optical Control
System (OCS), Model FS-5. The system consisted of a light source
and a detector. The film was passed through the system, between the
light source and the detector, with a 150-mm (6-inch) inspection
width. A total of 10 square meters of film area was inspected and
the gels with sizes of greater than 200 .mu.m were analyzed, and
then normalized per square foot of film.
[0109] Molecular weights and molecular weight distributions were
obtained using a PL-GPC 220 (Polymer Labs, an Agilent Company)
system equipped with a IR4 detector (Polymer Char, Spain) and three
Styragel HMW-6E GPC columns (Waters, Mass.) running at 145.degree.
C. The flow rate of the mobile phase 1,2,4-trichlorobenzene (TCB)
containing 0.5 g/L 2,6-di-t-butyl-4-methylphenol (BHT) was set at 1
mL/min, and polymer solution concentrations were in the range of
1.0-1.5 mg/mL, depending on the molecular weight. Sample
preparation was conducted at 150.degree. C. for nominally 4 hr with
occasional and gentle agitation, before the solutions were
transferred to sample vials for injection. An injection volume of
200 .mu.L was used. The integral calibration method was used to
deduce molecular weights and molecular weight distributions using a
Chevron Phillips Chemical Company's HDPE polyethylene resin,
MARLEX.RTM. BHB5003, as the broad standard. The integral table of
the broad standard was pre-determined in a separate experiment with
SEC-MALS. Mn is the number-average molecular weight, Mw is the
weight-average molecular weight, Mz is the z-average molecular
weight, My is viscosity-average molecular weight, and Mp is the
peak molecular weight (location, in molecular weight, of the
highest point of the molecular weight distribution curve).
[0110] The respective LMW component and HMW component properties
were determined by deconvoluting the molecular weight distribution
(see e.g., FIG. 6) of each polymer. The relative amounts of the LMW
and HMW components (weight percentages) in the polymer were
determined using a commercial software program (Systat Software,
Inc., PEAK FIT v. 4.05). The other molecular weight parameters for
the LMW and HMW components (e.g., Mn, Mw, Mz, etc., of each
component) were determined by using the deconvoluted data from the
PEAK FIT program, and applying a PEAK FIT Chromatography/Log Normal
4-Parameter (Area) Function and two peaks without any constraints
in deconvolution, per below (where a.sub.0=area; a.sub.1=center;
a.sub.2=width (>0); and a.sub.3=shape (>0, .noteq.1)):
y = a 0 .times. ln .function. ( 2 ) .times. ( a 3 2 - 1 ) a 2
.times. a 3 .times. ln .function. ( a 3 ) .times. .pi. .times. exp
.function. [ ln .function. ( a 3 2 ) 4 .times. .times. ln
.function. ( 2 ) ] .times. exp .function. [ - ln .function. ( 2 )
.times. ln .function. ( ( x - a 1 ) .times. ( a 3 2 - 1 ) a 2
.times. a 3 + 1 ) 2 ln .function. ( a 3 ) 2 ] ##EQU00001##
[0111] Melt rheological characterizations were performed as
follows. Small-strain (less than 10%) oscillatory shear
measurements were performed on an Anton Paar MCR rheometer using
parallel-plate geometry. All rheological tests were performed at
190.degree. C. The complex viscosity |.eta.*| versus frequency (c)
data were then curve fitted using the modified three parameter
Carreau-Yasuda (CY) empirical model to obtain the zero shear
viscosity--.eta..sub.0, characteristic viscous relaxation
time--.tau..sub..eta., and the breadth parameter--a (CY-a
parameter). The simplified Carreau-Yasuda (CY) empirical model is
as follows.
.eta. * ( .omega. ) = .eta. 0 [ 1 + ( .tau. .eta. .times. .omega. )
a ] ( 1 - n ) / a , ##EQU00002##
wherein: |.eta.*(.omega.)|=magnitude of complex shear viscosity;
[0112] .eta..sub.0=zero shear viscosity: [0113]
.tau..sub..eta.=viscous relaxation time (Tau(.eta.)); [0114]
a="breadth" parameter (CY-a parameter): [0115] n=fixes the final
power law slope, fixed at 2/11; and [0116] .omega.=angular
frequency of oscillatory shearing deformation.
[0117] Details of the significance and interpretation of the CY
model and derived parameters can be found in: C. A. Hieber and H.
H. Chiang, Rheol. Acta, 28, 321 (1989); C. A. Hieber and H. H.
Chiang, Polym. Eng. Sci., 32, 931 (1992); and R. B. Bird, R. C.
Armstrong and O. Hasseger, Dynamics of Polymeric Liquids. Volume 1,
Fluid Mechanics, 2nd Edition. John Wiley & Sons (1987); each of
which is incorporated herein by reference in its entirety. The tan
.delta. at 0.1 sec.sup.-1, tan .delta. at 100 sec.sup.-1, viscosity
at 0.1 sec.sup.-1, and viscosity at 100 sec.sup.-1 properties were
determined using the Carreau-Yasuda (CY) empirical model.
[0118] The long chain branches (LCBs) per 1000 total carbon atoms
of the overall polymer can be calculated using the method of Janzen
and Colby (J. Mol. Struct., 485/486, 569-584 (1999), incorporated
herein by reference in its entirety), from values of zero shear
viscosity, .eta..sub.o (determined from the Carreau-Yasuda model,
described hereinabove), and measured values of Mw obtained using a
Dawn EOS multiangle light scattering detector (Wyatt).
[0119] Metals content, such as the amount of catalyst residue in
the ethylene polymer or film/article, can be determined by ICP
analysis on a PerkinElmer Optima 8300 instrument. Polymer samples
can be ashed in a Thermolyne furnace with sulfuric acid overnight,
followed by acid digestion in a HotBlock with HCl and HNO.sub.3
(3:1 v:v).
[0120] Solid activator particle size distributions were determined
by using an aqueous suspension of the activator and a Microtrac
S3500 laser particle size analyzer. Conditions were set to "opaque"
with a run time of 30 sec, number of measurements 3, and shape
spherical. As a skilled artisan would readily recognize, supporting
the metallocene compound(s) on the solid activator would not impact
the particle size distribution, thus the particle size distribution
of the supported metallocene catalyst would be effectively the same
as the particle size distribution of the solid activator. Polymer
particle size distributions were obtained on a dry basis with a
Beckman-Coulter, model Fraunhofer RF780F LS 13 320 laser-based
particle size analyzer. Conditions were set to 0.7% residual, 9.9
inches of water of vacuum, 2% of obscuration, number of passes 3,
and a 23 sec run time.
Example A
Particle Size Distributions of Solid Activators
[0121] Solid activators were prepared as follows. A silica-coated
alumina having a surface area of 450 m.sup.2/g, a pore volume of
1.3 mL/g, and 38 wt. % silica was treated in three ways. In the
first method, 1 part of the silica-coated alumina by weight was
slurried in 5.7 parts by weight of water. Then, 0.055 parts by
weight of hydrofluoric acid were added, and the slurry was stirred
for several hours. During this time, fluorine was gradually
adsorbed, and when this was complete, the fluorided silica-coated
alumina was spray dried, producing a solid activator with an
average particle size of 48 .mu.m. This material was then given a
further treatment using an air-mill, also called a jet-mil, which
broke down the largest particles into many smaller ones. This
produced the Comparative 1 solid activator, with a d50 average
particle size (diameter) of 9.4 .mu.m.
[0122] In the second method, the same procedure was used, however,
rather than being subjected to jet-milling, the solid activator was
instead passed through a 270 mesh sieve. That which remained on the
screen was recycled, whereas that which passed through the screen
was captured for use later, producing the Inventive 2 solid
activator, with a d50 average particle size of 31.6 .mu.m.
[0123] In the third method, one part by weight of the same
silica-coated alumina was slurried in 4.8 parts by weight of water,
then 0.058 parts of tetrafluoroboric acid and 0.048 parts of zinc
oxide powder were added. After slurrying for several hours and
spray drying, this material was further refined using air
classification to remove the largest particles. Then, in a second
but similar step, this solid activator was further air-classified
to remove the smallest particles, resulting in the Inventive 1
solid activator, having a d50 average particle size of 19.3
.mu.m.
[0124] In a fourth method, an alumina having a surface area of 300
m/g and a pore volume of 1.3 mL/g was calcined at 600.degree. C.
Then, one part by weight of this material was slurried in 5.2 parts
by weight of water, following by adding 0.15 parts of sulfuric
acid. After slurrying for another 30 min and spray drying, this
procedure produced the Comparative 2 solid activator, having a d50
average particle size of 86.5 .mu.m.
[0125] FIG. 1 illustrates the particle size distributions of these
four solid activators (amount of particles by weight versus the
particle diameter plotted on a log-scale). Table 1 summarizes
various parameters calculated from the particle size distributions
of the four solid activators: Inventive 1, Inventive 2, Comparative
1, and Comparative 2. The Inventive 1 solid activator had the
narrowest particle size distribution and a d50 average particle
diameter larger than that of Comparative 1 and smaller than that of
Inventive 2 and Comparative 2.
[0126] The d50 average particle size of the Inventive 1 solid
activator was 19.3 .mu.m and the particle size span ((d90-d10)/d50)
was less than 1 (0.85). The Inventive 1 solid activator also had a
d10 particle size greater than 10 .mu.m (12.7 .mu.m), a d95
particle size less than 40 .mu.m (.about.34 .mu.m), and a ratio of
d90/d10 less than 3 (2.3). Further, less than 2% of the Inventive 1
solid activator had a particle size of less than 10 .mu.m, less
than 1% had a particle size of greater than 45 .mu.m, and at least
99% had a particle size of less than 50 .mu.m.
[0127] The d50 average particle size of the Inventive 2 solid
activator was 31.6 .mu.m and the particle size span ((d90-d10)/d50)
was less than 1.5 (1.23). The Inventive 2 solid activator also had
a d10 particle size greater than 10 .mu.m (11.2 .mu.m), a d95
particle size less than 60 .mu.m (.about.57 .mu.m), and a ratio of
d90/d10 less than 5 (4.5). Further, less than 5% of the Inventive 2
solid activator had a particle size of less than 10 .mu.m, less
than 20% had a particle size of greater than 45 .mu.m, and at least
88% had a particle size of less than 50 .mu.m.
Example B
Particle Size Distributions of the Resultant Polymer Powders
[0128] The four solid activators of Example A were then calcined at
600.degree. C. in dry air for eight hours, and afterward stored
under nitrogen until use. Each was tested in a commercial-scale
loop reactor, using two metallocenes simultaneously to produce a
nominal 7-9 HLMI ethylene/l-hexene copolymer with a nominal
0.948-0.950 density. The two metallocenes used are shown below.
During these experiments, the ethylene concentration was 4-6 wt. %,
the reactor temperature was 205.degree. F., and the residence time
was 50-75 min. The feed rate of hydrogen and each metallocene were
varied to achieve the target HLMI and density and this was
accomplished with a weight-to-weight feed ratio of MET 2 to MET 1
of 2.1-3.5 and a hydrogen feed rate of 0.15-0.3 lb H.sub.2/1000 lb
ethylene. Reactant concentrations in the precontactor were
30,000-50,000 ppm solid activator and 5000-6000 ppm
triisobutylaluminum, the total metallocene to solid activator
weight ratio was 0.6-0.7%, the triisobutylaluminum to solid
activator weight ratio was 0.12 to 0.19, and the residence time was
30 min.
##STR00007##
[0129] Particle size distributions of the polymers were obtained
and are shown in FIG. 2, while Table II list various parameters
determined from the distributions in FIG. 2. In Table II, the d50
average particle size of the Inventive 1 polymer powder was 235
.mu.m and the particle size span ((d90-d10)/d50) was less than 1.5
(1.3). The Inventive 1 polymer powder also had a d90 particle size
less than 500 .mu.m (462 .mu.m) and a ratio of d90/d10 less than 4
(3.1). Further, less than 3% (2.2%) of the Inventive 1 polymer
powder had a particle size of less than 100 .mu.m and less than 1%
had a particle size of greater than 1000 .mu.m.
[0130] The d50 average particle size of the Inventive 2 polymer
powder was 388 .mu.m and the particle size span ((d90-d10)/d50) was
less than 1.5 (1.37). The Inventive 2 polymer powder also had a d90
particle size less than 700 .mu.m (694 .mu.m) and a ratio of
d90/d10 less than 5 (4.2). Further, less than 5% (3.4%) of the
Inventive 2 polymer powder had a particle size of less than 100
.mu.m and less than 1% had a particle size of greater than 1000
.mu.m.
[0131] In slurry polymerization, one catalyst particle tends to
make one much-larger polymer particle, unless it is broken by
extreme mechanical forces. Thus, the shape of the polymer
particles, and also the polymer particle size distribution, tend to
replicate that of the catalyst particle. Thus, due to the small
average particle diameter of the Comparative 1 solid activator, and
the large percentage of particles less than 10 .mu.m (fines),
Comparative 1 resulted in severe transfer problems during
operations with both activator/catalyst and the resultant polymer.
In fact, the problem was so severe that the test had to be stopped
due to unmanageable plugging of a downstream polymer feed hopper.
Consequently, the Comparative 1 solid activator was deemed
completely unsuitable for commercial loop slurry
polymerization.
[0132] The Inventive 2 solid activator was found to be acceptable
during calcination operations, because it caused no transfer
difficulties during charging and discharging operations of the
calciner. Neither did it cause difficulties during the charging
operation to the reactor feed tank. However, the polymer made still
exhibited some minor difficulties with transfer of the polymer
powder in downstream drying and transfer operations. Several plugs
were obtained during the test, however, the transfer problems were
manageable and the test run continued successfully to the end.
[0133] In contrast, the Inventive 1 solid activator/catalyst
performed exceptionally well during the loop slurry polymerization
experiments, transferring easily and cleanly during calcination and
then to the reactor. The charging and discharging operations
offered very little resistance from packing or static. Likewise,
Inventive 1 made polymer powder that was also exceptional in its
transfer properties during the test. It discharged from the reactor
easily, with no plugs or fines or dust, and it performed well
during downstream purging/drying operations. Transfer to the
storage and later to the pelletizing silos went extremely well,
indicating that the smaller particle size offers less resistance
and has less tendency to "drop out" and pack.
[0134] The Comparative 2 solid activator/catalyst had a moderately
narrow size distribution, but with much larger diameters than the
other examples. This catalyst produced large polymer particles,
which are more prone to breakage, which can be seen in FIG. 2 by
the increased breadth of the polymer particle size distribution,
compared to that of the activator/catalyst particle size
distribution (FIG. 1). Note that the polymer has more small
particles than would be expected from the large narrow catalyst
particle size distribution. Thus, despite the larger overall size,
Comparative 2 produced more polymer fines than either of the
smaller Inventive examples.
[0135] The higher amount of polymer fines produced by Comparative 2
due to breakage also resulted in transfer difficulties downstream,
despite the overall larger average size. The larger particles also
caused problems in the reactor itself, because they have more
difficulty circulating around the loop. This is because large
particles tend to have higher terminal velocity, and thus they have
a greater tendency to "drop out" or fall. Because the circulation
pump must work against this tendency, it usually requires higher
amperage to circulate the larger particles and the pump reaches its
limit more quickly. This tends to limit the concentration of
polymer in the slurry, and thus ultimately, the final production
rate.
[0136] In contrast, the Inventive 1 solid activator/catalyst
performed exceptionally in the loop reactor. Because the PE
particles made were smaller, their terminal velocity in isobutane
was lower, compared to Inventive 2 and especially the larger
particles of Comparative 2. This resulted in the pump amperage
dropping significantly in comparison. The drop in required pump
power allows more concentrated slurries to be used, which increases
production rate. The catalyst from Inventive 1 also produced little
to no polymer fines, such as particles smaller that 100 .mu.m, or
smaller than 75 m, or smaller than 50 .mu.m. This is because it is
usually the larger particles breaking up that produce fines, and
the inventive catalysts had few or no larger particles. This also
helps production rates, because fines can cause localized
over-heating ("hot-spots") or fouling or plate-out as they stick to
walls and thermocouples by static and continue to polymerize
ethylene to build up "wall scale" that inhibits flow and heat
transfer. Thus, Inventive 1 represented the best reactor
performance, with respect to particle size distribution of both the
activator/catalyst and the resultant polymer.
[0137] Another important polymer attribute for loop slurry
polymerization is the concept of "gels." The term is used to
indicate visual and surface imperfections in the final polymer
article, most especially film products. Such imperfections or
"gels" in the film not only detract from the appearance of the
article (such as a bag), but the resulting bumps on the surface
also can cause printing defects. Gels can have many sources,
including contamination from dirt or other foreign material,
additive particles that are insufficiently blended into the molten
polymer during pelletizing extrusion, unreacted catalyst particles,
or other polymer particles left from previous production of other
polymer grades of higher molecular weight or from other sources
that were not successfully blended into the bulk polymer during
pelletizing extrusion.
[0138] Large catalyst particles, and the resulting large polymer
particles, also tend to make larger, more noticeable gels,
resulting in an inferior final product. The influence of
catalyst/polymer particle size on gel count is illustrated in FIG.
3. The graph represents a transition from one solid
activator/catalyst to another solid activator/catalyst. A solid
activator similar to Comparative 2 was used to produce the polymer.
The gel content was being measured about every three hours as the
polymer was made. Due to the long residence time of the overall
system, it took almost a day to fully replace one catalyst with the
other. On this occasion, the gel count was initially near 1000 gels
(>200 .mu.m) per square foot of film. At a time of about 32 hr,
the feeding of Comparative 2 was stopped and the feeding of
Inventive 1 was begun, although no other changes were made to the
reactor. Immediately, the gel count started dropping as the first
activator/catalyst, and its larger polymer particles, were
gradually replaced by the Inventive 1 activator/catalyst and the
smaller polymer particles it makes. This changed caused the gel
count to drop by almost two orders of magnitude, to less than 50
gels/ft.sup.2 and decreasing before the experiment was
completed.
[0139] Another problem that can result from the production of a
broad size distribution of polymer particles is segregation between
the sizes during handling. This is especially a problem when the
polymer particles of different sizes also have different molecular
weights and different densities. This can happen from many causes,
such as development of feedstock diffusion gradients through the
individual particles during production, non-uniform adsorption of
various catalyst components including the aluminum alkyl, selective
breakage, etc. FIG. 4 shows an example of this effect. Three
polymers were fluidized by nitrogen for a short time in a special
test designed to measure the tendency of powders to segregate (ASTM
6941). When the fluidization was stopped, the still polymer bed was
then sampled from the top, bottom, and middle positions. FIG. 4
shows the particle size distributions of one of these polymers,
made with the Comparative 2 solid activator, in comparison to the
original unfluidized composite sample. The Comparative 2 polymer
had a strong tendency to segregate, with small particles preferring
to rise to the top of the bed and large particles preferring to
sink to the bottom. This not only contributes to flow problems and
feeder "surging," but the smaller particles were also found to have
significantly lower molecular weight than the larger particles, so
that the polymer molecular weight exiting the pelletizing extruder
can vary over time due to particle settling upstream, causing the
pellet HLMI to vary even within the same lot of polymer powder.
[0140] In contrast, the Inventive 1 polymer powder exhibited little
or no tendency to segregate. The results of these segregation tests
are summarized in Table III, where the Inventive 1 polymer is
compared to two different polymers made with the Comparative 2
activator/catalyst. The difference between top and bottom of the
bed indicates the degree of separation. The percent change is the
difference in size between top and bottom divided by that of the
composite. The coefficient of variation is the standard deviation
of the three numbers (top, bottom, composite) divided by the
average of the three numbers. Surprisingly, all of the coefficient
of variation values at d10, d50, and d90 are significantly lower
for the Inventive 1 polymer compared to that of Comparative 2.
[0141] When a comonomer, such as 1-hexene, is introduced into the
reactor, it incorporates into the polymer, making the polymer less
crystalline, and therefore with a lower density. Larger particles
tend to incorporate a different amount of comonomer from that
incorporated by the smaller particles, resulting in different
densities. This is particularly problematic in dual metallocene
catalyst systems. The phenomenon can be caused by feedstock
diffusion gradients generated through the particles, or by
non-uniform composition of catalyst particles, or even through
reactor gradients such as the "hot-spots" described above. The
degree of heterogeneity in the polymer powder can thus be
quantified by a flotation test. That is, polymer powder was
slurried in isopropanol, which has a lower density than any polymer
particle. Therefore, all of the particles sink in the alcohol.
However, small increments of water were then added to the slurry to
raise the liquid density in small increments. As water was slowly
added, particles having the lowest density begin to float and they
were skimmed off the top, and dried. More water was then added and
more polymer particles rise to the top and the process is repeated.
Eventually, the density of the liquid was increased enough so that
all of the polymer particles, even those with the least comonomer
incorporated, rise to the top and were skimmed off. In this way,
the entire polymer powder was fractionated by particle density and
the amount of comonomer each particle incorporated.
[0142] An example of the flotation test is shown in FIG. 5. The
amount of floating polymer is plotted against the density of the
liquid for each increment of water added for the Inventive 1
polymer powder, the Inventive 2 polymer powder, and Comparative 2
polymer powder. The two inventive polymers had a much narrower
spread in the density of the polymer particles made, indicating
significantly better homogeneity within the powder. The density of
the polymer particles in Comparative 2 varied from 0.955 to 0.915,
for a density spread of 0.04 g/cm.sup.3. In contrast, the density
spreads for the two inventive polymers were only 0.003-0.005
g/cm.sup.3.
Examples 1-40
Polymer Properties
[0143] Pilot scale polymerizations were conducted using a 30-gallon
slurry loop reactor at a production rate of 30-33 pounds of polymer
per hour. Polymerizations were carried out under continuous
particle form process conditions in a loop reactor (also referred
to as a slurry process) by contacting a dual metallocene solution
in toluene and isobutane and possibly 1-hexene, an organoaluminum
solution (triisobutylaluminum, TIBA), and a solid activator in a
1-L stirred autoclave with continuous output to the loop reactor.
The TIBA and dual metallocene solutions were fed as separate
streams into the isobutane flush going into the autoclave. The
solid activator was also continuously flushed into the autoclave
with isobutane and the TIBA/metallocene mixture flowing together to
the autoclave. The isobutane flush used to transport the solid
activator into the autoclave was set at a rate that would result in
a residence time of 30 minutes in the autoclave. The total flow
from the autoclave then entered the loop reactor.
[0144] The ethylene used was polymerization grade ethylene obtained
from AirGas or Praxair which was then further purified through a
column of alumina-zeolite adsorbent (dehydrated at 230-290.degree.
C. in nitrogen). Polymerization grade 1-hexene (obtained from
Chevron Phillips Chemical Company) was used and was further
purified by distillation and passed through a column of
alumina-zeolite absorbent dehydrated at 230-290.degree. C. in
nitrogen. The loop reactor was liquid full, 15.2 cm in diameter,
and had a volume of 30 gallons (113.6 liters). Liquid isobutane was
used as the diluent. Hydrogen was added to tune the molecular
weight and/or HLMI of the polymer product. The isobutane used was
polymerization grade isobutane (obtained from Enterprise) that was
further purified by distillation and subsequently being passed
through a column of alumina (dehydrated at 230-290.degree. C. in
nitrogen). Co-catalyst TIBA was added in a concentration in 30 to
90 ppm based on the weight of the diluent in the polymerization
reactor.
[0145] Reactor conditions included a reactor pressure of 600 psig,
a mol % ethylene of 4-7 wt % (based on isobutane diluent), a
1-hexene content of 0.4-0.8 mol % (based on isobutane diluent),
0.5-0.8 lb of hydrogen per 1000 lb of ethylene, and a
polymerization temperature of 88-98.degree. C. The reactor was
operated to have a residence time of 75 min. Total metallocene
concentrations in the reactor were within a range of 1 to 3 parts
per million (ppm) by weight of the diluent. The solid activator was
fed to the reactor at the rate of 4-9 g per hour.
[0146] Polymer was removed from the reactor at the rate of 30-33
lb/hr and passed through a flash chamber and a purge column.
Nitrogen was fed to the purge column to ensure the powder/fluff was
hydrocarbon free. The structures for metallocenes MET 1 and MET 2
that were used in the catalyst system are shown below (the weight
ratio of MET 1:MET 2 was in the 0.3:1 to 1.5:1 range to produce the
desired polymer composition):
##STR00008##
[0147] The particle size distributions of the polymer powder/fluff
produced using this dual catalyst system containing the solid
activators Inventive 1, Inventive 2, Comparative 1, and Comparative
2 are summarized in FIG. 2 and Table II. Polymer particle size
distributions from the pilot plant experiments were very similar to
those described above. The polymer powder made using the Inventive
1 solid activator had the narrowest particle size distribution,
followed by Inventive 2, Comparative 1, and finally Comparative
2.
[0148] The following data tables contain polymers from both the
commercial reactor (Example 1-15) and the pilot plant (Examples
16-40), all made using solid activators Inventive 1, Inventive 2,
or Comparative 2. The Comparative 1 solid activator performed so
poorly in the loop reactor that no useable polymer could be
collected to analyze. In each example below, the resulting polymer
powder was mixed and pelletized using a conventional pelletizing
extruder to form resin pellets. Then, for some examples, 1-mil
blown films were produced for dart impact testing.
[0149] Table IV lists the solid activator used to make each
polymer, as well as the resultant density, HLMI, and puncture
resistance (dart impact strength) of 1-mil film blown for each
polymer. FIG. 6 illustrates the bimodal molecular weight
distributions (amount of polymer versus the logarithm of molecular
weight) of the polymers of Examples 1, 4, 12, 18, 21, and 36. The
polymers of Examples 1-15 had densities ranging from 0.947 to 0.95
g/cm.sup.3, HLMI values ranging from 5 to 8 g/10 min, and dart
impact values averaging 390 g/mil, unexpectedly higher than the
average dart impact of 320 g/mil for Examples 16-40. While not
wishing to be bound by theory, it is believed that the improved
homogeneity of comonomer incorporation and polymer powder/fluff
density (e.g., FIG. 5) results in the improvement in dart impact
strength, even though the overall bulk polymer densities are
unchanged.
[0150] Table V summarizes certain molecular weight characteristics
of the polymers of Examples 1-40. The Mw values ranged from 250,000
to 320,000 g/mol and the ratios of Mw/Mn ranged from 21 to 42 for
the polymers of Example 1-15, whereas the Mw values were below
250,000 g/mol and the Mw/Mn values were below 20 for many of
Examples 16-40.
[0151] The bimodal molecular weight distributions from each of
these polymers were then deconvoluted into their respective high-MW
and low-MW components (LMW and HMW) as described herein. The
molecular weight parameters for the LMW and HMW components (e.g.,
Mn, Mw, and Mz of each component) of each example were determined
by using the deconvoluted data from the PEAK FIT program, and are
listed in Tables VI and Vil. As shown in these tables, the ethylene
polymers of Examples 1-15 contained 60-67 wt. % of the LMW
component, which had a Mw of 32,000-40,000 g/mol and a ratio of
Mz/Mw from 2.3 to 3. The HMW component had a Mn ranging from
290,000 to 400,000 g/mol. The combined polymer properties of
Examples 1-15 are not found in any of Examples 16-40.
[0152] Table VIII summarizes certain rheological characteristics at
190.degree. C. for the polymers of Examples 1-40. These were
determined using the Carreau-Yasuda model as described above. The
polymers of Examples 1-15 had CY-a parameters of 0.49-0.62,
relaxation times (.tau.(.eta.) from 1.5 to 4 sec, viscosities at
100 sec.sup.-1 (.eta. @ 100) from 2100 to 3500 Pa-sec, and ratios
of the viscosity at 0.1 sec.sup.-1 to the viscosity at 100
sec.sup.-1 (.eta. @ 0.1/.eta. @ 100) ranging from 41 to 68.
[0153] In summary, these polymer properties demonstrate the
unexpected relationship between the particle size distribution of
the solid activators (or the supported metallocene catalysts) and
the polymer rheology and molecular weight distribution,
particularly as it pertains to the LMW and the HMW components.
TABLE-US-00001 TABLE I Particle size distributions of solid
activators. Example Inventive 1 Inventive 2 Comparative 1
Comparative 2 Mv, .mu.m 20.22 30.4 11.53 92.63 Mn, .mu.m 5.63 6.29
3.01 40.43 Mv/Mn 3.59 4.83 3.83 2.29 Mp, .mu.m 20.17 33.0 13.08
88.00 Std Dev, .mu.m 5.97 14.41 7.23 35.07 Mp-Mv, .mu.m 0.2% 7.9%
1.55 5.3% Mv/Mp 1.00 0.92 0.88 1.05 Ma, .mu.m 16.37 21.82 6.90
74.74 Mp/Ma 1.23 1.51 1.90 1.18 Mp/Ma, .mu.m 3.80 11.18 6.18 13.26
Full 49.93 112.2 86.84 368.34 Breadth, .mu.m 1/2 ht 12.76 39.14
21.56 73.47 Breadth, .mu.m Weight Per- centile, .mu.m 10% 12.74
11.23 3.39 47.47 20% 15.06 19.45 4.60 61.77 30% 16.59 24.58 5.91
70.46 40% 17.95 28.30 7.49 78.53 50% 19.31 31.58 9.36 86.48 60%
20.79 34.81 11.47 95.1 70% 22.55 38.41 13.88 105.3 80% 24.94 42.94
16.95 119.1 90% 29.15 50.19 22.09 142.9 95% 33.77 57.64 27.81 168.7
90/10 2.29 4.47 6.52 3.01 90-10, .mu.m 16.41 38.96 18.70 95.43
80/20 1.66 2.21 3.68 1.93 80-20, .mu.m 9.88 23.49 12.35 57.33
95-10, .mu.m 21.03 46.41 24.42 121.23 95-50, .mu.m 14.46 26.06
18.45 82.22 50-10, .mu.m 6.57 20.35 5.97 39.01 Span, (D90 - 0.85
1.23 2.00 1.10 D10)/D50 Less than 1.3 4.9 49.4 0.0 10 .mu.m, % At
least 0.9 16.4 1.0 91.7 45 .mu.m, % Less than 99.1 88.8 99.0 10.3
50 .mu.m, %
TABLE-US-00002 TABLE II Particle size distributions of PE powder
made using four solid activators. Inventive Inventive Com- Com-
Solid Activator 1 2 parative 1 parative 2 Mv, .mu.m 277.0 410.9
94.2 895.6 Median, .mu.m 235.4 387.7 79.2 803.6 Mean/Median 1.18
1.06 1.19 1.11 Mode, .mu.m 223.4 471.1 37.5 1091 Std. Dev., .mu.m
156.4 205.3 82.8 524.1 Coeff. Of Variation 56% 50% 88% 62% Full
width, .mu.m 430.2 998.0 326.0 2480.0 Weight Percentile, .mu.m 10%
150.9 163.5 27.1 138.7 25% 186.7 255.9 45.2 436.1 50% 235.4 387.7
78.0 803.6 75% 306.3 539.9 118.2 1231 90% 462.0 694.4 162.2 1622
Weight Percentile, % <1 .mu.m 0.0% 0.0% 0.0% 0% <5 .mu.m 0.0%
0.0% 0.2% 0.0% <10 um 0.1% 0.1% 1.0% 0.7% <50 .mu.m 0.7% 1.1%
28.8% 3.2% <100 .mu.m 2.2% 3.4% 65.0% 7.3% <200 .mu.m 31.8%
15.5% 95.6% 13.7% <1000 .mu.m 99.6% 99.3% 100.0% 62.8% Weight %
on sieve # 1000 1.1% 2.6% 47.8% 5.3% 200 12.2% 7.6% 39.1% 5.4% 100
46.2% 17.3% 11.2% 5.4% 60 28.0% 35.9% 0.8% 8.3% 40 11.1% 35.1% 1.1%
28.8% 20 1.3% 1.7% 0.0% 39.1% 12 0.0% 0.0% 0.0% 7.7% thru 100 mesh
13.3% 10.1% 86.9% 10.7% thru 200 mesh 1.1% 2.6% 47.8% 5.3% Span,
(D90 - D10)/D50 1.32 1.37 1.73 1.85
TABLE-US-00003 TABLE III Polymer powder segregation test results.
Catalyst Sample d10, .mu.m d50, .mu.m d90, .mu.m Mean, .mu.m
Comparative 2 Top 241 737 1409 787 Comparative 2 Middle 340 807
1522 868 Comparative 2 Bottom 439 880 1490 921 Comparative 2
Composite 353 830 1549 889 Comparative 2 Change 56.2% 17.1% 5.3%
15.1% Comparative 2 Coeff of Var. 29.1% 8.8% 4.0% 7.9% Comparative
2 Top 176 554 1056 590 Comparative 2 Middle 367 704 1178 738
Comparative 2 Bottom 415 782 1290 816 Comparative 2 Composite 339
716 1230 748 Comparative 2 Change 70.6% 31.7% 19.0% 30.1%
Comparative 2 Coeff of Var. 39.6% 17.0% 10.0% 16.0% Inventive 1 Top
143 228 453 228 Inventive 1 Middle 154 238 457 238 Inventive 1
Bottom 158 237 467 237 Inventive 1 Composite 151 235 462 235
Inventive I Change 10.0% 3.5% 3.0% 3.5% Inventive 1 Coeff of Var.
5.1% 2.2% 1.5% 2.2%
TABLE-US-00004 TABLE IV Summary of polymer examples produced using
solid activators. Solid Density HLMI Dart Impact Example Activator
(g/cc) (g/10 min) (g/mil) 1 Inventive 1 0.9478 6.1 -- 2 Inventive 2
0.9486 6.9 378 3 Inventive 1 0.9487 8.0 -- 4 Inventive 1 0.9485 7.6
-- 5 Inventive 1 0.9486 6.5 -- 6 Inventive 1 0.9488 5.6 -- 7
Inventive 2 0.9493 5.5 462 8 Inventive 2 0.9482 6.4 316 9 Inventive
2 0.9485 6.7 422 10 Inventive 2 0.9488 6.3 524 11 Inventive 2
0.9486 6.5 350 12 Inventive 2 0.9484 6.1 292 13 Inventive 2 0.9485
6.0 448 14 Inventive 2 0.9481 5.1 398 15 Inventive 2 0.9480 5.8 342
16 Comparative 2 0.9495 6.7 150 17 Comparative 2 0.9501 7.2 158 18
Comparative 2 0.9471 5.7 131 19 Comparative 2 0.9478 6.3 220 20
Comparative 2 0.9503 6.1 195 21 Comparative 2 0.9419 6.4 481 22
Comparative 2 0.9409 5.3 371 23 Comparative 2 0.9545 7.6 189 24
Comparative 2 0.9464 13.0 311 25 Comparative 2 0.9431 3.4 409 26
Comparative 2 0.9495 12.1 -- 27 Comparative 2 0.9491 22.0 217 28
Comparative 2 0.9448 5.4 590 79 Comparative 2 0.9453 5.4 592 30
Comparative 2 0.9482 11.3 499 31 Comparative 2 0.9479 11.8 360 32
Comparative 2 0.9481 10.7 -- 33 Comparative 2 0.9493 6.4 399 34
Comparative 2 0.9579 6.0 166 35 Comparative 2 0.9513 41.5 189 36
Comparative 2 0.9529 8.0 -- 37 Comparative 2 0.9574 23.1 -- 38
Comparative 2 0.9578 19.5 -- 39 Comparative 2 0.9535 8.4 -- 40
Comparative 2 0.9537 7.0 --
TABLE-US-00005 TABLE V Molecular Weight Characterization (g/mol)
Example Mn/1000 Mw/1000 Mz/1000 Mv/1000 Mp/1000 Mw/Mn Mz/Mw 1 8.6
287 1339 206 24 33.2 4.67 2 8.1 287 1331 205 24 35.4 4.63 3 7.5 310
1399 223 22 41.6 4.51 4 8.5 298 1302 215 23 35.1 4.37 5 9.3 312
1338 227 24 33.4 4.29 6 8.1 262 1271 186 24 32.6 4.84 7 9.6 279
1119 204 20 29.1 4.01 8 9.0 251 1028 186 22 28.0 4.09 9 12.0 273
1053 203 24 22.8 3.86 10 12.1 278 1079 207 25 22.9 3.88 11 13.0 277
1085 207 516 21.3 3.92 12 12.3 282 1112 210 523 23.0 3.94 13 11.9
269 1060 201 490 22.7 3.94 14 12.7 291 1140 217 523 23.0 3.91 15
13.1 287 1121 214 530 21.9 3.90 16 12.6 311 1376 227 34 24.6 4.42
17 15.9 314 1455 229 40 19.8 4.63 18 22.6 397 2001 285 68 17.6 5.05
19 38.2 438 2632 308 81 11.5 6.01 20 10.2 282 1275 207 29 27.8 4.51
21 8.6 182 506 147 239 21.1 2.78 22 6.5 183 494 148 258 28.1 2.70
23 6.4 182 549 143 258 28.5 3.02 24 5.5 182 593 140 328 33.2 3.26
25 8.5 259 868 200 420 30.5 3.35 26 6.2 188 767 138 388 30.6 4.07
27 5.6 172 683 126 349 30.6 3.97 28 8.8 254 877 207 436 28.8 3.45
29 10.1 263 869 200 483 26.1 3.30 30 8.9 256 1016 187 19 28.9 3.96
31 8.3 251 1233 179 19 30.2 4.92 32 8.1 242 961 177 17 29.8 3.97 33
8.9 268 1027 199 479 30.2 3.83 34 9.5 268 1085 197 472 28.3 4.05 35
7.6 221 1041 155 18 29.1 4.71 36 10.1 192 752 162 353 19.1 3.91 37
10.5 178 709 133 17 17.0 3.97 38 10.7 181 712 136 16 16.9 3.93 39
10.6 195 678 139 351 18.3 3.48 40 10.7 200 689 144 333 18.6
3.45
TABLE-US-00006 TABLE VI Molecular Weight Characterization
(g/mol)-Low molecular weight component Mn/ Mw/ Mz/ Example 1000
1000 1000 Mw/Mn Mz/Mw Wt. % 1 7.6 39.7 108 5.15 2.76 66.9 2 7.2
37.6 107 5.21 2.85 62.6 3 5.8 34.5 92 5.90 2.66 62.4 4 6.2 34.4 91
5.52 2.65 62.2 5 6.5 36.4 101 5.58 2.77 60.8 6 6.2 34.8 89 5.64
2.56 67.0 7 6.4 32.5 96 5.11 2.94 62.6 8 6.2 32.4 80 5.20 2.46 60.5
9 8.2 38.9 101 4.76 2.58 62.7 10 8.2 39.1 101 4.75 2.59 62.7 11 8.2
35.0 83 4.28 2.37 60.3 12 8.2 39.4 104 4.80 2.63 62.4 13 7.7 36.1
93 4.67 2.58 61.4 14 8.2 38.4 99 4.67 2.59 61.3 15 8.4 38.0 97 4.51
2.55 61.6 16 8.7 43.9 105 5.07 2.38 65.7 17 11.2 50.3 109 4.49 2.17
68.7 18 18.4 71.4 135 3.87 1.90 71.5 19 29.7 89.4 163 3.00 1.82
73.5 20 6.5 32.1 71 4.96 2.20 60.8 21 1.9 8.3 18 4.32 2.21 32.5 22
2.2 9.8 23 8.25 2.32 34.4 23 2.2 9.7 24 6.42 2.43 37.3 24 2.6 11.1
26 5.13 2.31 43.8 25 5.7 31.2 110 4.59 3.51 53.1 26 3.4 14.7 38
5.89 2.59 53.8 27 3.3 16.5 45 5.89 2.75 57.0 28 4.8 22.1 54 5.18
2.44 51.4 29 5.5 22.3 53 4.67 2.40 52.5 30 6.1 28.8 79 4.38 2.75
63.7 31 5.8 27.9 67 5.28 2.40 64.6 32 5.4 26.4 67 4.24 2.52 62.9 33
5.5 26.7 72 4.76 2.69 57.3 34 5.6 27.4 75 4.64 2.73 59.0 35 6.0
28.5 72 4.42 2.54 69.8 36 7.1 28.9 77 4.09 2.67 56.3 37 6.8 23.9 56
3.50 2.35 61.5 38 6.7 23.0 54 3.45 2.34 59.5 39 6.0 21.0 49 3.48
2.35 53.6 40 5.5 19.5 48 3.52 2.45 50.5
TABLE-US-00007 TABLE VII Molecular Weight Characterization (g/mol)
- High molecular weight component Example Mn/1000 Mw/1000 Mz/1000
Mw/Mu Mz/Mw 1 381 770 1392 2.02 1.81 2 329 666 1208 2.03 1.81 3 359
767 1452 2.14 1.89 4 342 743 1383 2.17 1.86 5 353 761 1468 2.16
1.93 6 335 744 1407 2.22 1.89 7 378 728 1311 1.92 1.80 8 296 596
1074 2.02 1.80 9 385 681 1138 1.77 1.67 10 394 694 1164 1.76 1.68
11 351 662 1150 1.88 1.74 12 395 701 1199 1.78 1.71 13 363 650 1116
1.79 1.72 14 393 704 1211 1.79 1.72 15 392 701 1202 1.79 1.71 16
473 832 1487 1.76 1.79 17 522 924 1684 1.77 1.82 18 619 1280 2471
2.07 1.93 19 368 1456 3213 3.95 2.21 20 307 639 1105 2.08 1.73 21
90 266 472 2.97 1.77 22 110 301 523 2.73 1.74 23 98 301 551 3.06
1.83 24 99 315 562 3.19 1.78 25 338 576 926 1.71 1.61 26 124 384
702 3.10 1.83 27 178 408 687 2.30 1.68 28 264 525 856 1.99 1.63 29
237 530 858 2.24 1.62 30 391 668 1073 1.71 1.61 31 358 650 1145
1.81 1.76 32 342 618 1009 1.81 1.63 33 310 594 999 1.92 1.68 34 327
615 1043 1.88 1.70 35 398 705 1145 1.77 1.63 36 234 433 690 1.85
1.59 37 223 425 705 1.91 1.66 38 213 411 682 1.93 1.66 39 204 396
661 1.95 1.67 40 190 375 635 1.98 1.69
TABLE-US-00008 TABLE VIII Rheological Characterization at
190.degree. C. Zero shear Tau(.eta.) CY-a .eta. @ 0.1 Tan d @ 0.1
.eta. @ 100 Tan d @ 100 .eta. @ 0.1/ Example (Pa-sec) (sec)
parameter (Pa-sec) (degrees) (Pa-sec) (degrees) .eta. @ 100 1
282,400 3.53 0.531 140,200 1.97 2172 0.354 64.5 2 220,800 2.01
0.534 128,400 2.48 2635 0.373 48.7 3 373,800 3.42 0.582 204,500
2.08 3016 0.340 67.8 4 363,700 3.40 0.580 198,800 2.08 2948 0.340
67.4 5 402,800 3.19 0.574 222,100 2.13 3423 0.344 64.9 6 295,600
3.61 0.538 147,900 1.97 2246 0.351 65.9 7 266,500 2.58 0.620
166,000 2.45 2721 0.337 61.0 8 197,800 1.63 0.491 111,500 2.55 2692
0.403 41.4 9 251,000 2.37 0.525 137,800 2.30 2628 0.370 52.4 10
261,100 2.44 0.539 145,900 2.31 2693 0.364 54.2 11 261,900 2.40
0.536 146,000 2.31 2728 0.365 53.5 12 264,200 2.30 0.536 149,000
2.35 2849 0.367 52.3 13 223,700 2.15 0.537 128,600 2.43 2547 0.369
50.5 14 273,400 2.30 0.547 157,400 2.39 2971 0.363 53.0 15 264,800
2.35 0.544 150,600 2.35 2818 0.363 53.4 16 356,900 3.84 0.565
183600 1.96 2611 0.341 70.3 17 469,800 5.48 0.535 204100 1.67 2564
0.341 79.6 18 4,167,000 63.37 0.307 277100 0.93 2707 0.385 102.4 19
-- -- 0.048 232800 0.71 2964 0.603 78.5 20 239,900 2.38 0.563
140500 2.39 2556 0.356 55.0 21 33,940 0.16 0.600 30,410 10.01 2757
0.533 11.0 22 49,650 0.20 0.575 42,970 8.02 3343 0.519 12.9 23
42,850 0.19 0.539 36,160 7.31 2897 0.551 12.5 24 47,760 0.32 0.525
37,720 5.48 2235 0.503 16.9 25 230,900 1.67 0.602 154,900 2.95 3292
0.356 47.1 26 43,610 0.40 0.543 34,230 5.18 1756 0.468 19.5 27
51,990 0.50 0.553 40,180 4.80 1806 0.444 22.2 28 208,600 1.50 0.601
143,000 3.11 3247 0.361 44.0 29 210,100 1.68 0.596 139,900 2.92
2986 0.358 46.9 30 200,100 2.43 0.600 123,100 2.47 2128 0.344 57.8
31 214,200 2.61 0.613 131,700 2.42 2161 0.339 60.9 32 176,800 2.16
0.581 108,900 2.55 2049 0.354 53.1 33 199,000 1.64 0.532 121,000
2.70 2784 0.383 43.5 34 197,000 1.85 0.570 123,700 2.69 2561 0.363
48.3 35 158,700 2.88 0.573 89,770 2.22 1460 0.347 61.5 36 69,890
0.50 0.519 50,570 4.28 2540 0.503 19.9 37 55,410 0.51 0.471 37,830
3.86 1728 0.496 21.9 38 57,770 0.49 0.469 39,600 3.91 1853 0.501
21.4 39 71,170 0.47 0.492 39,600 3.91 1853 0.501 21.4 40 70,570
0.43 0.483 50,570 4.28 2540 0.503 19.9
[0154] The invention is described above with reference to numerous
aspects and specific examples. Many variations will suggest
themselves to those skilled in the art in light of the above
detailed description. All such obvious variations are within the
full intended scope of the appended claims. Other aspects of the
invention can include, but are not limited to, the following
(aspects are described as "comprising" but, alternatively, can
"consist essentially of" or "consist of"):
[0155] Aspect 1. A catalyst composition comprising a metallocene
compound; a solid activator; and optionally, a co-catalyst; wherein
the solid activator (or the supported metallocene catalyst) has a
d50 average particle size in a range from 15 to 50 .mu.m; and a
particle size span ((d90-d10)/d50) in a range from 0.5 to 1.5.
[0156] Aspect 2. The composition defined in aspect 1, wherein the
d50 average particle size is in any range disclosed herein, e.g.,
from 15 to 40 .mu.m, from 15 to 25 .mu.m, from 20 to 30 .mu.m, from
17 to 40 .mu.m, from 17 to 27 .mu.m, or from 17 to 25 .mu.m.
[0157] Aspect 3. The composition defined in aspect 1 or 2, wherein
the span ((d90-d10)/d50) is an any range disclosed herein, e.g.,
from 0.5 to 1.2, from 0.6 to 1.4, from 0.6 to 1.3, from 0.6 to 1.1,
from 0.7 to 1.4, or from 0.7 to 1.2.
[0158] Aspect 4. The composition defined in any one of the
preceding aspects, wherein the solid activator (or the supported
metallocene catalyst) has a d10 particle size in any range
disclosed herein, e.g., greater than or equal to 10 .mu.m, greater
than or equal to 11 .mu.m, greater than or equal to 12 .mu.m, in a
range from 10 to 20 .mu.m, or in a range from 10 to 18 .mu.m.
[0159] Aspect 5. The composition defined in any one of the
preceding aspects, wherein the solid activator (or the supported
metallocene catalyst) has a d95 particle size in any range
disclosed herein, e.g., less than or equal to 65 .mu.m, less than
or equal to 60 .mu.m, in a range from 25 to 65 .mu.m, or in a range
from 28 to 60 .mu.m.
[0160] Aspect 6. The composition defined in any one of the
preceding aspects, wherein the solid activator (or the supported
metallocene catalyst) has a ratio of d90/d10 in any range disclosed
herein, e.g., from 1.5 to 5, from 1.5 to 4, from 1.5 to 3, from 1.8
to 5, from 1.8 to 4, or from 1.8 to 3.
[0161] Aspect 7. The composition defined in any one of the
preceding aspects, wherein the amount of the solid activator (or
the supported metallocene catalyst) having a particle size of less
than 10 .mu.m is in any range disclosed herein, e.g., less than or
equal to 15 wt. %, less than or equal to 10 wt. %, less than or
equal to 8 wt. %, less than or equal to 5 wt. %, or less than or
equal to 2 wt. %.
[0162] Aspect 8. The composition defined in any one of the
preceding aspects, wherein the amount of the solid activator (or
the supported metallocene catalyst) having a particle size of
greater than 45 .mu.m is in any range disclosed herein, e.g., less
than or equal to 20 wt. %, less than or equal to 15 wt. %, less
than or equal to 10 wt. %, less than or equal to 5 wt. %, or less
than or equal to 2 wt. %.
[0163] Aspect 9. The composition defined in any one of the
preceding aspects, wherein the amount of the solid activator (or
the supported metallocene catalyst) having a particle size of less
than 50 .mu.m is in any range disclosed herein, e.g., at least 85
wt. %, at least 88 wt. %, at least 90 wt. %, or at least 95 wt.
%.
[0164] Aspect 10. The composition defined in any one of aspects
1-9, wherein the solid activator comprises fluorided alumina,
chlorided alumina, bromided alumina, sulfated alumina, fluorided
silica-alumina, chlorided silica-alumina, bromided silica-alumina,
sulfated silica-alumina, fluorided silica-zirconia, chlorided
silica-zirconia, bromided silica-zirconia, sulfated
silica-zirconia, fluorided silica-titania, fluorided silica-coated
alumina, fluorided-chlorided silica-coated alumina, sulfated
silica-coated alumina, phosphated silica-coated alumina, or any
combination thereof.
[0165] Aspect 11. The composition defined in any one of aspects
1-9, wherein the activator comprises fluorided alumina, sulfated
alumina, fluorided silica-alumina, sulfated silica-alumina,
fluorided silica-coated alumina, fluorided-chlorided silica-coated
alumina, sulfated silica-coated alumina, or any combination
thereof.
[0166] Aspect 12. The composition defined in any one of aspects
1-9, wherein the solid activator comprises a fluorided solid oxide
and/or a sulfated solid oxide.
[0167] Aspect 13. The composition defined in any one of aspects
1-12, wherein the catalyst composition comprises a co-catalyst,
e.g., any suitable co-catalyst.
[0168] Aspect 14. The composition defined in any one of aspects
1-13, wherein the co-catalyst comprises any organoaluminum compound
disclosed herein.
[0169] Aspect 15. The composition defined in aspect 14, wherein the
organoaluminum compound comprises trimethylaluminum,
triethylaluminum, triisobutylaluminum, or a combination
thereof.
[0170] Aspect 16. The composition defined in any one of the
preceding aspects, wherein the catalyst composition is
substantially free of aluminoxane compounds, organoboron or
organoborate compounds, ionizing ionic compounds, or combinations
thereof.
[0171] Aspect 17. The composition defined in any one of the
preceding aspects, wherein the catalyst composition comprises a
single metallocene compound, e.g., a bridged metallocene compound
or an unbridged metallocene compound.
[0172] Aspect 18. The composition defined in any one of aspects
1-16, wherein the composition comprises metallocene component I
comprising any unbridged metallocene compound disclosed herein and
metallocene component II comprising any bridged metallocene
compound disclosed herein.
[0173] Aspect 19. The composition defined in aspect 18, wherein
metallocene component II comprises a bridged zirconium or hafnium
based metallocene compound.
[0174] Aspect 20. The composition defined in aspect 18, wherein
metallocene component II comprises a bridged zirconium or hafnium
based metallocene compound with an alkenyl substituent.
[0175] Aspect 21. The composition defined in aspect 18, wherein
metallocene component II comprises a bridged zirconium or hafnium
based metallocene compound with an alkenyl substituent and a
fluorenyl group.
[0176] Aspect 22. The composition defined in aspect 18, wherein
metallocene component 11 comprises a bridged zirconium or hafnium
based metallocene compound with a cyclopentadienyl group and a
fluorenyl group, and with an alkenyl substituent on the bridging
group and/or on the cyclopentadienyl group.
[0177] Aspect 23. The composition defined in any one of aspects
18-22, wherein metallocene component II comprises a bridged
metallocene compound having an aryl group substituent on the
bridging group.
[0178] Aspect 24. The composition defined in any one of aspects
18-23, wherein metallocene component I comprises an unbridged
zirconium or hafnium based metallocene compound containing two
cyclopentadienyl groups, two indenyl groups, or a cyclopentadienyl
and an indenyl group.
[0179] Aspect 25. The composition defined in any one of aspects
18-23, wherein metallocene component I comprises an unbridged
zirconium or hafnium based metallocene compound containing two
cyclopentadienyl groups.
[0180] Aspect 26. The composition defined in any one of aspects
18-23, wherein metallocene component I comprises an unbridged
Zirconium or hafnium based metallocene compound containing two
indenyl groups.
[0181] Aspect 27. The composition defined in any one of aspects
18-23, wherein metallocene component I comprises an unbridged
zirconium or hafnium based metallocene compound containing a
cyclopentadienyl and an indenyl group.
[0182] Aspect 28. The composition defined in any one of aspects
18-23, wherein metallocene component I comprises an unbridged
zirconium based metallocene compound containing an
alkyl-substituted cyclopentadienyl group and an alkenyl-substituted
indenyl group.
[0183] Aspect 29. The composition defined in any one of aspects
18-28, wherein a weight ratio of metallocene component I to
metallocene component II in the catalyst composition is in any
range disclosed herein, e.g., from 10:1 to 1:10, from 5:1 to 1:5,
or from 2:1 to 1:2.
[0184] Aspect 30. The composition defined in any one of aspects
18-29, wherein the catalyst composition is produced by a process
comprising contacting, in any order, metallocene component I,
metallocene component II, the solid activator, and the
co-catalyst.
[0185] Aspect 31. The composition defined in any one of the
preceding aspects, wherein a catalyst activity of the catalyst
composition is in any range disclosed herein, e.g., from 150 to
10,000, from 500 to 7,500, or from 1,000 to 5,000 grams, of
ethylene polymer per gram of solid activator per hour, under slurry
polymerization conditions, with a triisobutylaluminum co-catalyst,
using isobutane as a diluent, and with a polymerization temperature
of 90.degree. C. and a reactor pressure of 390 psig.
[0186] Aspect 32. A (slurry) polymerization process comprising:
contacting the catalyst composition defined in any one of aspects
1-31 with an olefin monomer and an optional olefin comonomer in a
polymerization reactor system comprising a loop slurry reactor
under polymerization conditions to produce an olefin polymer.
[0187] Aspect 33. The process defined in aspect 32, wherein the
olefin monomer comprises any olefin monomer disclosed herein, e.g.,
any C.sub.2-C.sub.20 olefin.
[0188] Aspect 34. The process defined in aspect 32, wherein the
olefin monomer and the optional olefin comonomer independently
comprise a C.sub.2-C.sub.20 alpha-olefin.
[0189] Aspect 35. The process defined in any one of aspects 32-34,
wherein the olefin monomer comprises ethylene.
[0190] Aspect 36. The process defined in any one of aspects 32-35,
wherein the catalyst composition is contacted with ethylene and an
olefin comonomer comprising a C.sub.3-C.sub.10 alpha-olefin.
[0191] Aspect 37. The process defined in any one of aspects 32-36,
wherein the catalyst composition is contacted with ethylene and an
olefin comonomer comprising 1-butene, 1-hexene, 1-octene, or a
mixture thereof.
[0192] Aspect 38. The process defined in any one of aspects 32-37,
wherein the polymerization reactor system comprises only one loop
slurry reactor.
[0193] Aspect 39. The process defined in any one of aspects 32-37,
wherein the polymerization reactor system comprises two or more
reactors, at least one of which is the loop slurry reactor.
[0194] Aspect 40. The process defined in any one of aspects 32-39,
wherein the olefin polymer comprises any olefin polymer disclosed
herein.
[0195] Aspect 41. The process defined in any one of aspects 32-40,
wherein the olefin polymer comprises an ethylene homopolymer, an
ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, and/or
an ethylene/1-octene copolymer.
[0196] Aspect 42. The process defined in any one of aspects 32-41,
wherein the olefin polymer comprises an ethylene/1-hexene
copolymer.
[0197] Aspect 43. The process defined in any one of aspects 32-42,
wherein the polymerization conditions comprise a polymerization
reaction temperature in a range from 60.degree. C. to 120.degree.
C. and a reaction pressure in a range from 200 to 1000 psig (1.4 to
6.9 MPa).
[0198] Aspect 44. The process defined in any one of aspects 32-43,
wherein the polymerization conditions are substantially constant,
e.g., for a particular polymer grade.
[0199] Aspect 45. The process defined in any one of aspects 32-44,
wherein no hydrogen is added to the polymerization reactor
system.
[0200] Aspect 46. The process defined in any one of aspects 32-44,
wherein hydrogen is added to the polymerization reactor system.
[0201] Aspect 47. The process defined in any one of aspects 32-46,
wherein the olefin polymer has a density in any range disclosed
herein, e.g., from 0.90 to 0.97, from 0.92 to 0.96, from 0.93 to
0.955, or from 0.94 to 0.955 g/cm.sup.3.
[0202] Aspect 48. The process defined in any one of aspects 32-47,
wherein the olefin polymer has a Mw in any range disclosed herein,
e.g., from 100 to 50) kg/mol, from 150 to 350 kg/mol, or from 200
to 320 kg/mol.
[0203] Aspect 49. The process defined in any one of aspects 32-48,
wherein the olefin polymer has a ratio of Mw/Mn in any range
disclosed herein, e.g., from 5 to 40, from 7 to 25, or from 8 to
15.
[0204] Aspect 50. The process defined in any one of aspects 32-49,
wherein the olefin polymer has a HLMI in any range disclosed
herein, e.g., from 1 to 80, from 2 to 40, from 2 to 30, or from 1
to 20 g/10 min.
[0205] Aspect 51. The process defined in any one of aspects 32-50,
wherein the olefin polymer contains, independently, less than 0.1
ppm (by weight), less than 0.08 ppm, less than 0.05 ppm, or less
than 0.03 ppm, of Mg, V. Ti, or Cr.
[0206] Aspect 52. The process defined in any one of aspects 32-51,
wherein the olefin polymer is characterized by a film gel count in
any range disclosed herein, e.g., less than 100, less than 50, less
than 25, less than 10, or less than 5 gels per ft.sup.2 of 25
micron film (gels encompass any film defect with a size greater
than 200 microns).
[0207] Aspect 53. An olefin polymer produced by the process defined
in any one of aspects 32-52.
[0208] Aspect 54. An ethylene polymer (e.g., in the form of
pellets) having (or characterized by): a high load melt index
(HLMI) in a range from 4 to 10 g/10 min a density in a range from
0.944 to 0.955 g/cm.sup.3; and a higher molecular weight component
and a lower molecular weight component, wherein: the higher
molecular weight component has a Mn in a range from 280,000 to
440,000 g/mol; and the lower molecular weight component has a Mw in
a range from 30,000 to 45,000 g/mol, and a ratio of Mz/Mw in a
range from 2.3 to 3.4.
[0209] Aspect 55. The polymer defined in aspect 54, wherein the
ethylene polymer has a HLMI in any range disclosed herein, e.g.,
from 4 to 9, from 4 to 8, from 5 to 10, from 5 to 9, or from 5 to 8
g/10 min.
[0210] Aspect 56. The polymer defined in aspect 54 or 55, wherein
the ethylene polymer has a density in any range disclosed herein,
e.g., from 0.944 to 0.952, from 0.945 to 0.955, from 0.945 to
0.953, from 0.945 to 0.95, from 0.946 to 0.955, or from 0.946 to
0.952 g/cm.sup.3.
[0211] Aspect 57. The polymer defined in any one of aspects 54-56,
wherein the lower molecular weight component has a Mw in any range
disclosed herein, e.g., from 30,000 to 43,000, from 30,000 to
41,000, from 31,000 to 45,000, from 31,000 to 42,000, from 31,000
to 40,000, from 32,000 to 44,000, or from 32,000 to 42,000
g/mol.
[0212] Aspect 58. The polymer defined in any one of aspects 54-57,
wherein the higher molecular weight component has a Mn in any range
disclosed herein, e.g., from 280,000 to 425,000, from 280,000 to
400,000, from 290,000 to 410,000, from 300,000 to 440,000, or from
300,000 to 400,000 g/mol.
[0213] Aspect 59. The polymer defined in any one of aspects 54-58,
wherein the lower molecular weight component has a ratio of Mz/Mw
in any range disclosed herein, e.g., from 2.3 to 3.2, from 2.35 to
3.0, from 2.4 to 3.3, from 2.4 to 3.2, or from 2.4 to 3.1.
[0214] Aspect 60. The polymer defined in any one of aspects 54-59,
wherein an amount of the lower molecular weight component, based on
the total polymer, is in any range of weight percentages disclosed
herein, e.g., from 56 to 72 wt. %, from 56 to 70 wt. %, from 58 to
72 wt. %, from 58 to 70 wt. %, or from 60 to 68 wt. %
[0215] Aspect 61. The polymer defined in any one of aspects 54-60,
wherein the lower molecular weight component has a Mn in any range
disclosed herein, e.g., from 4,000 to 10,000, from 4,000 to 9,000,
from 5.000 to 10,000, from 5.000 to 9,000, or from 5,500 to 8,500
g/mol.
[0216] Aspect 62. The polymer defined in any one of aspects 54-61,
wherein the lower molecular weight component has a Mz in any range
disclosed herein, e.g., from 70,000 to 130,000, from 70,000 to
115,000, from 75,000 to 130,000, from 75,000 to 120,000, or from
75,000 to 115,000 g/mol.
[0217] Aspect 63. The polymer defined in any one of aspects 54-62,
wherein the higher molecular weight component has a ratio of Mw/Mn
in any range disclosed herein, e.g., from 1.6 to 2.4, from 1.7 to
2.4, from 1.7 to 2.3, from 1.8 to 2.4, from 1.8 to 2.3, from 1.9 to
2.4, or from 1.9 to 2.3.
[0218] Aspect 64. The polymer defined in any one of aspects 54-63,
wherein the higher molecular weight component has a Mz in any range
disclosed herein, e.g., from 900,000 to 1,600,000, from 1,000,000
to 1,500,000, from 1,000,000 to 1,400,000, from 1,100,000 to
1,600,000, or from 1,100,000 to 1,500,000 g/mol.
[0219] Aspect 65. The polymer defined in any one of aspects 54-64,
wherein the ethylene polymer has a Mw in any range disclosed
herein, e.g., from 230,000 to 330,000, from 230,000 to 320,000,
from 240,000 to 330,000, or from 240,000 to 320,000 g/mol.
[0220] Aspect 66. The polymer defined in any one of aspects 54-65,
wherein the ethylene polymer has a ratio of Mw/Mn in any range
disclosed herein, e.g., from 20 to 45, from 20 to 42, from 22 to
44, from 25 to 45, or from 25 to 42.
[0221] Aspect 67. The polymer defined in any one of aspects 54-66,
wherein the ethylene polymer has a CY-a parameter in any range
disclosed herein, e.g., from 0.45 to 0.65, from 0.47 to 0.63, from
0.47 to 0.61, from 0.5 to 0.65, from 0.5 to 0.63, or from 0.5 to
0.6.
[0222] Aspect 68. The polymer defined in any one of aspects 54-67,
wherein the ethylene polymer has a relaxation time (Tau(eta) or
.tau.(.eta.)) in any range disclosed herein, e.g., from 1.5 to 4,
from 1.5 to 3.7, from 2 to 4, or from 2 to 3.6 sec.
[0223] Aspect 69. The polymer defined in any one of aspects 54-68,
wherein the ethylene polymer has a viscosity at 100 sec.sup.-1 (eta
@ 100 or .eta. @ 100) in any range disclosed herein, e.g., from
2000 to 3600, from 2000 to 3500, from 2100 to 3600, or from 2100 to
3500 Pa-sec.
[0224] Aspect 70. The polymer defined in any one of aspects 54-69,
wherein the ethylene polymer has a ratio of viscosity at 0.1
sec.sup.-1 to viscosity at 100 sec.sup.-1 (.eta. @ 0.1/.eta. @ 100)
in any range disclosed herein, e.g., from 38 to 72, from 40 to 68,
from 46 to 68, or from 52 to 72.
[0225] Aspect 71. The polymer defined in any one of aspects 54-70,
wherein the ethylene polymer contains, independently, less than 0.1
ppm (by weight), less than 0.08 ppm, less than 0.05 ppm, or less
than 0.03 ppm, of Mg, V, Ti, or Cr.
[0226] Aspect 72. The polymer defined in any one of aspects 54-71,
wherein the ethylene polymer is characterized by a film gel count
in any range disclosed herein, e.g., less than 100, less than 50,
less than 25, less than 10, or less than 5 gels per ft.sup.2 of 25
micron film (gels encompass any film defect with a size greater
than 200 microns).
[0227] Aspect 73. The polymer defined in any one of aspects 54-72,
wherein the ethylene polymer is a single reactor product, e.g., not
a post-reactor blend of two polymers, for instance, having
different molecular weight characteristics.
[0228] Aspect 74. The polymer defined in any one of aspects 54-73,
wherein the ethylene polymer comprises an ethylene/.alpha.-olefin
copolymer.
[0229] Aspect 75. The polymer defined in any one of aspects 54-74,
wherein the ethylene polymer comprises an ethylene homopolymer, an
ethylene/1-butene copolymer, an ethylene/1-hexene copolymer, and/or
an ethylene/1-octene copolymer.
[0230] Aspect 76. The polymer defined in any one of aspects 54-75,
wherein the ethylene polymer comprises an ethylene/1-hexene
copolymer.
[0231] Aspect 77. An article comprising the ethylene polymer
defined in any one of aspects 54-76.
[0232] Aspect 78. An article comprising the ethylene polymer
defined in any one of aspects 54-76, wherein the article is an
agricultural film, an automobile part, a bottle, a container for
chemicals, a drum, a fiber or fabric, a food packaging film or
container, a food service article, a fuel tank, a geomembrane, a
household container, a liner, a molded product, a medical device or
material, an outdoor storage product, outdoor play equipment, a
pipe, a sheet or tape, a toy, or a traffic barrier.
[0233] Aspect 79. A film comprising (or produced from) the polymer
defined in any one of aspects 54-76.
[0234] Aspect 80. The film defined in aspect 79, wherein the film
has a dart impact strength in any range disclosed herein, e.g.,
greater than or equal to 150 g/mil, greater than or equal to 250
g/mil, from 150 to 750 g/mil, or from 250 to 600 g/mil.
[0235] Aspect 81. The film defined in aspect 79 or 80, wherein the
film has a gel count in any range disclosed herein, e.g., less than
100, less than 50, less than 25, less than 10, or less than 5 gels
per ft.sup.2 of film (gels encompass any film defect with a size
greater than 200 microns).
[0236] Aspect 82. The film defined in any one of aspects 79-81,
wherein the film has an average thickness in any range disclosed
herein, e.g., from 0.4 to 20 mils, from 0.5 to 8 mils, from 0.8 to
5 mils, from 0.7 to 2 mils, or from 0.7 to 1.5 mils.
[0237] Aspect 83. The film defined in any one of aspects 79-82,
wherein the film is a blown film.
[0238] Aspect 84. The process defined in any one of aspects 32-52,
wherein the olefin polymer produced is defined in any one of
aspects 54-76.
[0239] Aspect 85. An ethylene polymer defined in any one of aspects
54-76 produced by the process defined in any one of aspects
32-52.
[0240] Aspect 86. An ethylene polymer (fluff or powder) composition
having (or characterized by): a d50 average particle size in a
range from 150 to 600 .mu.m; a particle size span ((d90-d10)/d50)
in a range from 0.5 to 1.6; less than or equal to 20 wt. % of the
composition with a particle size of less than 100 .mu.m; and less
than or equal to 5 wt. % of the composition with a particle size of
greater than 1000 .mu.m.
[0241] Aspect 87. The composition defined in aspect 86, wherein the
d50 average particle size is in any range disclosed herein, e.g.,
from 150 to 450 .mu.m, from 150 to 325 .mu.m, from 150 to 300
.mu.m, from 175 to 325 .mu.m, from 175 to 275 .mu.m, from 200 to
400 .mu.m, or from 200 to 275 .mu.m.
[0242] Aspect 88. The composition defined in aspect 86 or 87,
wherein the span ((d90-d10)/d50) is an any range disclosed herein,
e.g., from 0.75 to 1.5, from 1 to 1.6, from 1.1 to 1.6, or from 1.1
to 1.5.
[0243] Aspect 89. The composition defined in any one of aspects
86-88, wherein the amount of the composition having a particle size
of greater than 1000 .mu.m is in any range disclosed herein, e.g.,
less than or equal to 3 wt. %, less than or equal to 2 wt %, or
less than or equal to 1 wt. %.
[0244] Aspect 90. The composition defined in any one of aspects
86-89, wherein the amount of the composition having a particle size
of less than 100 .mu.m is in any range disclosed herein, e.g., less
than or equal to 10 wt. %, less than or equal to 5 wt. %, from 1 to
10 wt. %, or from 1 to 5 wt. %.
[0245] Aspect 91. The composition defined in any one of aspects
86-90, wherein the composition has a d90 particle size in any range
disclosed herein, e.g., from 300 to 800 .mu.m, from 300 to 600
.mu.m, from 350 to 550 .mu.m, from 375 to 525 .mu.m, from 400 to
750 .mu.m, or from 400 to 500 .mu.m.
[0246] Aspect 92. The composition defined in any one of aspects
86-91, wherein the composition has a ratio of d90/d10 in any range
disclosed herein, e.g., from 2 to 5, from 2 to 4, from 2.2 to 3.8,
from 2.4 to 5, from 2.4 to 3.6, or from 2.7 to 3.3.
[0247] Aspect 93. The composition defined in any one of aspects
86-92, wherein the composition has a HLMI in any range disclosed
herein, e.g., from 4 to 10, from 4 to 9, from 4 to 8, from 5 to 10,
from 5 to 9, or from 5 to 8 g/10 min.
[0248] Aspect 94. The composition defined in any one of aspects
86-93, wherein the composition has a density in any range disclosed
herein, e.g., from 0.944 to 0.955, from 0.944 to 0.952, from 0.945
to 0.955, from 0.945 to 0.953, from 0.945 to 0.95, from 0.946 to
0.955, or from 0.946 to 0.952 g/cm.sup.3.
* * * * *