U.S. patent application number 11/114352 was filed with the patent office on 2006-10-26 for fibers and fabrics prepared from blends of homopolymers and copolymers.
This patent application is currently assigned to Fina Technology, Inc.. Invention is credited to John O. Bieser, Mike McLeod, Darek Wachowicz.
Application Number | 20060240733 11/114352 |
Document ID | / |
Family ID | 37187537 |
Filed Date | 2006-10-26 |
United States Patent
Application |
20060240733 |
Kind Code |
A1 |
Bieser; John O. ; et
al. |
October 26, 2006 |
Fibers and fabrics prepared from blends of homopolymers and
copolymers
Abstract
A fiber comprising a propylene polymer composition is disclosed.
The composition comprises a resin blend of from about 75 to about
95 weight percent of a Ziegler-Natta or metallocene catalyzed
isotactic polypropylene homopolymer, and from about 95 to about 75
weight percent of a metallocene catalyzed polypropylene copolymer.
In this blend the copolymer component includes a comonomer in an
amount from about 0.05 to about 25 weight percent, based on the
copolymer. Non-woven fabrics prepared by thermally bonding the
inventive fibers show improved tensile strengths, particularly
machine direction, at comparable basis weights that are at least
about 5 percent higher than those of fabrics prepared using
identical preparation techniques but from the isotactic
polypropylene homopolymer alone.
Inventors: |
Bieser; John O.; (Houston,
TX) ; McLeod; Mike; (Kemah, TX) ; Wachowicz;
Darek; (Friendswood, TX) |
Correspondence
Address: |
FINA TECHNOLOGY INC
PO BOX 674412
HOUSTON
TX
77267-4412
US
|
Assignee: |
Fina Technology, Inc.
Houston
TX
|
Family ID: |
37187537 |
Appl. No.: |
11/114352 |
Filed: |
April 25, 2005 |
Current U.S.
Class: |
442/414 ;
428/359; 428/364; 442/400; 442/401 |
Current CPC
Class: |
Y10T 442/68 20150401;
Y10T 442/681 20150401; Y10T 428/2904 20150115; Y10T 442/696
20150401; D04H 1/56 20130101; D04H 3/16 20130101; D01F 6/46
20130101; Y10T 428/2913 20150115 |
Class at
Publication: |
442/414 ;
428/359; 428/364; 442/401; 442/400 |
International
Class: |
D04H 1/00 20060101
D04H001/00; D04H 3/00 20060101 D04H003/00; D04H 1/56 20060101
D04H001/56; D04H 3/16 20060101 D04H003/16 |
Claims
1. A fiber, spunbond fabric, or melt blown fabric comprising a
polymer composition comprising a resin blend of from about 60 to
about 99 weight percent of a Ziegler-Natta or metallocene catalyzed
isotactic polypropylene homopolymer, and from about 1 to about 40
weight percent of a metallocene catalyzed propylene copolymer,
wherein the copolymer comprises a comonomer in an amount from about
0.05 to about 25 weight percent, based on the copolymer.
2. The fiber of claim 1 wherein the polypropylene homopolymer is
Ziegler-Natta catalyzed.
3. The fiber of claim 1 wherein the metallocene used to catalyze
polymerization of the propylene copolymer is a substituted
isospecific CpFlu-type catalyst.
4. The fiber of claim 1 wherein the metallocene used to catalyze
polymerization of the propylene copolymer is racemic
Me.sub.2Si(2-Me-4-PhInd).sub.2ZrCl.sub.2 on 0.7/1 MAO on P10
silica, Ph is phenyl; Ind is indenyl; and MAO is
methylalumoxane.
5. The fiber of claim 1 wherein the comonomer is ethylene and it is
present in an amount of from about 1 to about 20 weight percent,
based on the copolymer.
6. An article comprising a fiber of claim 1.
7. The article of claim 6 wherein the article is a carpet or
twine.
8. The article of claim 6 wherein the article is a staple
fiber.
9. The article of claim 6 wherein the article is a spunbond
fabric.
10. The article of claim 6 wherein the article is a continuous
filament.
11. A thermally bonded non-woven fabric comprising a fiber
comprising a polymer composition comprising a resin blend of from
about 75 to about 95 weight percent of a Ziegler-Natta or
metallocene catalyzed isotactic polypropylene homopolymer, and from
about 95 to about 75 weight percent of a metallocene catalyzed
polypropylene copolymer, wherein the copolymer comprises a
comonomer in an amount from about 0.05 to about 25 weight percent,
based on the copolymer.
12. The fabric of claim 11 wherein the thermal bonding is carried
out at a temperature of at least about 240.degree. C.
13. The fabric of claim 12 wherein the thermal bonding is carried
out at a temperature of at least about 250.degree. C.
14. The fabric of claim 11 wherein the fabric has a machine
direction tensile strength that is at least 5 percent higher than
the tensile strength of a thermally bonded non-woven fabric made
from a fiber that is made from the polypropylene homopolymer alone,
the fabrics having basis weights of 10 gsm to 100 gsm.
15. The fabric of claim 11 wherein the fabric has a machine
direction tensile strength that is at least 10 percent higher than
the tensile strength of a thermally bonded non-woven made from a
fiber that is made from the polypropylene homopolymer alone, the
fabrics having a basis weight of 17 gsm.
16. An article comprising the fabric of claim 11.
17. The article of claim 11 being selected from the group
consisting of baby diaper coverstock, feminine hygiene coverstock,
agricultural fabric, housewrap, medical gowns, drapes, and
catamenial devices.
18. A method for preparing a non-woven fabric comprising melt
spinning a polymer composition comprising a resin blend of from
about 75 to about 95 weight percent of a Ziegler-Natta or
metallocene catalyzed isotactic polypropylene homopolymer, and from
about 95 to about 75 weight percent of a metallocene catalyzed
propylene copolymer, wherein the copolymer comprises a comonomer in
an amount from about 0.05 to about 25 weight percent, based on the
copolymer, to form a fiber, and thermally bonding the fiber at a
temperature of at least about 240.degree. C.
19. The method of claim 18 wherein the polypropylene homopolymer is
Ziegler-Natta catalyzed.
20. The method of claim 18 wherein the metallocene used to catalyze
polymerization of the propylene copolymer is a substituted
isospecific CpFlu-type catalyst.
21. The method of claim 18 wherein the catalyst is racemic
Me.sub.2Si(2Me-4-PhInd).sub.2ZrCl.sub.2 on 0.7/1 MAO on P10 silica;
Ph is phenyl; Ind is indenyl; and MAO is methylalumoxane.
22. The method of claim 16 wherein the comonomer is ethylene, and
it is present in an amount of from about 1 to about 10 weight
percent, based on the copolymer.
Description
BACKGROUND OF THE INVENTION
[0001] 1. Technical Field
[0002] This invention relates to the field of fibers and more
specifically to the field of fibers and fabrics prepared from
blends of polypropylene homopolymers and copolymers.
[0003] 2. Background of the Art
[0004] Homopolymers and copolymers of polypropylene are typically
polymerized in continuous polymerization reactors, such as, for
example, loop reactors. To produce these polymers one or more
monomer streams are generally introduced into the selected reactor
and then circulated with an appropriate catalyst. Ziegler-Natta or
metallocene catalysts may be employed. The resulting polymers may
be subjected to appropriate purification and post-processing steps
and then made into end products using conventional techniques such
as injection molding and extrusion. These end products may include
fibers, which may then be used to prepare woven and non-woven
products.
[0005] Propylene polymer fibers and fabrics are widely used in many
applications including twine, carpet, medical gowns and drapes, and
diapers. The optimization of processing characteristics and
properties of propylene based fibers and fabrics has been the
subject of intense effort. When the fibers are used to form
fabrics, specifically nonwoven fabrics, various methods of thermal
bonding are employed. To accomplish this it is desirable to have
high strength when bonding at the lowest possible temperatures.
Unfortunately, many polypropylene fabrics exhibit relatively poor
strength properties, and the resins used to prepare them may also
present challenges relating to melt spinning and overall melt
processing. It would therefore be desirable to have a means or
method of providing propylene-based fabric and fibers with improved
thermal bonding characteristics, softness and fabric strength
properties which may be prepared from resins having desirable melt
spinning and melt processing characteristics.
SUMMARY OF THE INVENTION
[0006] In one aspect, the invention is a fiber, spunbond fabric, or
melt blown fabric including a polymer composition that includes a
resin blend of from about 60 to about 99 weight percent of a
Ziegler-Natta or metallocene catalyzed isotactic polypropylene
homopolymer, and from about 1 to about 40 weight percent of a
metallocene catalyzed propylene copolymer. The copolymer includes a
comonomer in an amount from about 0.05 to about 25 weight (or
higher) percent, based on the copolymer.
[0007] In another aspect, the invention is an article including a
fiber prepared using a polymer composition that includes a resin
blend of from about 60 to about 99 weight percent of a
Ziegler-Natta or metallocene catalyzed isotactic polypropylene
homopolymer, and from about 1 to about 40 weight percent of a
metallocene catalyzed propylene copolymer. The copolymer includes a
comonomer in an amount from about 0.05 to about 25 weight percent,
based on the copolymer.
[0008] Another aspect of the invention is a thermally bonded
non-woven fabric made using a fiber including a polymer composition
including a resin blend of from about 75 to about 95 weight percent
of a Ziegler-Natta or metallocene catalyzed isotactic polypropylene
homopolymer, and from about 95 to about 75 weight percent of a
metallocene catalyzed polypropylene copolymer. The copolymer
includes a comonomer in an amount from about 0.05 to about 25
weight percent, based on the copolymer.
[0009] An aspect of the invention is an article including a
thermally bonded non-woven fabric made using a fiber including a
polymer composition including a resin blend of from about 75 to
about 95 weight percent of a Ziegler-Natta or metallocene catalyzed
isotactic polypropylene homopolymer, and from about 95 to about 75
weight percent of a metallocene catalyzed polypropylene copolymer.
The copolymer includes a comonomer in an amount from about 0.05 to
about 25 weight percent, based on the copolymer.
[0010] In still another aspect, the invention is a method for
preparing a non-woven fabric, the method including melt spinning a
polymer composition including a resin blend of from about 75 to
about 95 weight percent of a Ziegler-Natta or metallocene catalyzed
isotactic polypropylene homopolymer, and from about 95 to about 75
weight percent of a metallocene catalyzed propylene copolymer. The
copolymer includes a comonomer in an amount from about 0.05 to
about 25 weight percent, based on the copolymer. The method also
includes forming a fiber and thermally bonding the fiber at a
temperature of at least about 240.degree. C.
DETAILED DESCRIPTION OF THE INVENTION
[0011] Disclosed herein are fibers and non-woven fabrics that may
be prepared from a specific blend of metallocene catalyzed
polypropylene copolymers and either metallocene catalyzed, or
Ziegler-Natta catalyzed, isotactic polypropylene homopolymers. The
blend may be in the form of discreet resin blends or in the form of
in-situ reactor blends. The resin blend may exhibit good melt
spinning processability for preparing fibers. These fibers may be
used to form non-woven fabrics in particular, using conventional
processes including the spunbond or carded staple process. In
either of these processes, the result may be a fabric that exhibits
improved tensile strength and other properties, particularly when
compared to fabrics prepared using the same homopolymer alone. In
other words, incorporation of a given proportion of a metallocene
catalyzed copolymer in the starting resin improves the strength
properties of the fiber and/or fabric when compared with the
strength properties attained by the homopolymer alone.
[0012] The resin blend includes a major proportion of an isotactic
polypropylene homopolymer and a minor proportion of a random
copolymer. These polymers may each be prepared using any
conventional polymerization method known or used in the art.
Reactor types may include, for example, loop, slurry, continuous
stirred tank, or other, and polymerization protocol and conditions
may be determined accordingly, as are well known to those of
ordinary skill in the art. Gas, slurry, solution phase, and high
pressure autoclave processes are all contemplated hereby. For
example, a slurry polymerization process may be selected and will
generally use pressures of from about 1 to about 100 atmospheres
(about 0.1 to about 10 MPa) or greater, and temperatures from about
60.degree. C. to about 150.degree. C. In some embodiments the
temperature is from about 50.degree. C. to about 120.degree. C. In
such a polymerization a suspension of solid, particulate polymer is
formed in a liquid or supercritical polymerization medium to which
propylene (and, for the copolymer, a comonomer) and often hydrogen,
along with a selected catalyst, are added. The liquid employed in
the polymerization medium may be, for example, an alkane or
cycloalkane. This medium desirably remains liquid under the
conditions of polymerization and is also desirably relatively
inert. For example, hexane or isobutene are often employed. Such
polymerizations may be conducted in batch or continuous mode and
may take place in one reactor or may be carried out in a series of
reactors. The amount of time will depend upon the catalyst and
reaction conditions. In general, propylene may desirably be
homopolymerized or copolymerized for a time period sufficient to
yield the intended final homopolymer or copolymer, typically from
about 15 to about 120 minutes. In one embodiment the polymerization
is continued for a time of from about 30 to about 60 minutes.
[0013] In the case of the copolymer, one or more comonomers is also
added along with the propylene. In one embodiment the comonomer is
a C.sub.2 or C.sub.4-C.sub.16 compound, desirably C.sub.2 or
C.sub.4-C.sub.8. In another embodiment the comonomer is desirably
ethylene (C.sub.2). The comonomer level in the copolymer is
desirably limited. In one embodiment the comonomer is desirably
present in the final copolymer in an amount from about 0.05 to
about 25 percent by weight of the copolymer. In another embodiment
the comonomer is desirably present in an amount from about 1 to
about 10 percent by weight of the final copolymer. Feed rate of the
ethylene may be adjusted according to the rate of its incorporation
into the copolymer under the selected polymerization conditions.
Such adjustment will be easily within the skill of those in the
art.
[0014] Hydrogen may be added to the polymerization system as a
molecular weight regulator, depending upon the particular
properties of the product desired and the specific catalyst used.
When two catalysts having different hydrogen responses are used,
the addition of hydrogen may affect the molecular weight
distribution of the polymer product and may therefore be employed
with the intent to tailor the molecular weight distribution for a
specific purpose. This whole section is confusing, and maybe
irrelevant. Narrow MWD is desired for spunbond fiber, either by
metallocene catalsyst or vis-breaking via peroxide. I have not
established the correlation between the MW of the blend resin with
the host.
[0015] The catalyst that is desirably selected for preparing either
just the copolymer, or for both the homopolymer and the copolymer,
is a metallocene catalyst. Metallocene catalysts may be
characterized generally as coordination compounds incorporating one
or more cyclopentadienyl (Cp) groups (which may be substituted or
unsubstituted, each substitution being the same or different)
coordinated with a transition metal through pi bonding.
[0016] The Cp substituent groups may be linear, branched or cyclic
hydrocarbyl radicals. The cyclic hydrocarbyl radicals may further
form other contiguous ring structures, including, for example
indenyl, azulenyl and fluorenyl groups. These additional ring
structures may also be substituted or unsubstituted by hydrocarbyl
radicals, such as C.sub.1 to C.sub.20 hydrocarbyl radicals.
[0017] A specific example of a metallocene catalyst is a bulky
ligand metallocene compound generally represented by the formula:
[L].sub.mM[A].sub.n; where L is a bulky ligand, A is a leaving
group, M is a transition metal and m and n are such that the total
ligand valency corresponds to the transition metal valency. For
example m may be from 1 to 3 and n may be from 1 to 3.
[0018] The metal atom "M" of the metallocene catalyst compound, as
described throughout the specification and claims, may be selected
from Groups 3 through 12 atoms and lanthanide Group atoms in one
embodiment; and selected from Groups 3 through 10 atoms in a more
particular embodiment, and selected from Sc, Ti, Zr, Hf, V, Nb, Ta,
Mn, Re, Fe, Ru, Os, Co, Rh, Ir, and Ni in yet a more particular
embodiment; and selected from Groups 4, 5 and 6 atoms in yet a more
particular embodiment, and Ti, Zr, Hf atoms in yet a more
particular embodiment, and Zr in yet a more particular embodiment.
The oxidation state of the metal atom "M" may range from 0 to +7 in
one embodiment; and in a more particular embodiment, is +1, +2, +3,
+4 or +5; and in yet a more particular embodiment is +2, +3 or +4.
The groups bound the metal atom "M" are such that the compounds
described below in the formulas and structures are electrically
neutral, unless otherwise indicated.
[0019] The bulky ligand generally includes a cyclopentadienyl group
(Cp) or a derivative thereof. The Cp ligand(s) form at least one
chemical bond with the metal atom M to form the "metallocene
catalyst compound". The Cp ligands are distinct from the leaving
groups bound to the catalyst compound in that they are not highly
susceptible to substitution/abstraction reactions.
[0020] Cp typically includes 7-bonded and/or fused ring(s) or ring
systems. The ring(s) or ring system(s) typically include atoms
selected from group 13 to 16 atoms, for example, carbon, nitrogen,
oxygen, silicon, sulfur, phosphorus, germanium, boron, aluminum and
combinations thereof, wherein carbon makes up at least 50% of the
ring members. Non-limiting examples include cyclopentadienyl,
cyclopentaphenanthrenyl, indenyl, benzindenyl, fluorenyl,
tetrahydroindenyl, octahydrofluorenyl, cyclooctatetraenyl,
cyclopentacyclododecene, phenanthrindenyl, 3,4-benzofluorenyl,
9-phenylfluorenyl, 8-H-cyclopent[a]acenaphthylenyl,
7-H-dibenzofluorenyl, indeno[1,2-9]anthrene, thiophenoindenyl,
thiophenofluorenyl, hydrogenated versions thereof (e.g.,
4,5,6,7-tetrahydroindenyl, or "H.sub.4Ind"), substituted versions
thereof, and heterocyclic versions thereof.
[0021] Cp substituent groups may include hydrogen radicals, alkyls,
alkenyls, alkynyls, cycloalkyls, aryls, acyls, aroyls, alkoxys,
aryloxys, alkylthiols, dialkylamines, alkylamidos, alkoxycarbonyls,
aryloxycarbonyls, carbomoyls, alkyl- and dialkylcarbamoyls,
acyloxys, acylaminos, aroylaminos, and combinations thereof. More
particular non-limiting examples of alkyl substituents include
methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopentyl,
cyclohexyl, benzyl, phenyl, methylphenyl, and tert-butylphenyl
groups and the like, including all their isomers, for example
tertiary-butyl, isopropyl, and the like. Other possible radicals
include substituted alkyls and aryls such as, for example,
fluoromethyl, fluoroethyl, difluroethyl, iodopropyl, bromohexyl,
chlorobenzyl and hydrocarbyl substituted organometalloid radicals
including trimethylsilyl, trimethylgermyl, methyldiethylsilyl and
the like; and halocarbyl-substituted organometalloid radicals
including tris(trifluoromethyl)silyl,
methylbis(difluoromethyl)silyl, bromomethyldimethylgermyl and the
like; and disubstituted boron radicals including dimethylboron for
example; and disubstituted Group 15 radicals including
dimethylamine, dimethylphosphine, diphenylamine,
methylphenylphosphine, Group 16 radicals including methoxy, ethoxy,
propoxy, phenoxy, methylsulfide and ethylsulfide. Other
substituents R include olefins such as but not limited to
olefinically unsaturated substituents including vinyl-terminated
ligands, for example 3-butenyl, 2-propenyl, 5-hexenyl and the like.
In one embodiment, at least two R groups, two adjacent R groups in
one embodiment, are joined to form a ring structure having from 3
to 30 atoms selected from the group consisting of carbon, nitrogen,
oxygen, phosphorus, silicon, germanium, aluminum, boron and
combinations thereof. Also, a substituent group R group such as
1-butanyl may form a bonding association to the element M.
[0022] Each anionic leaving group is independently selected and may
include any leaving group, such as halogen ions, hydrides, C.sub.1
to C.sub.12 alkyls, C.sub.2 to C.sub.12 alkenyls, C.sub.6 to
C.sub.12 aryls, C.sub.7 to C.sub.20 alkylaryls, C.sub.1 to C.sub.12
alkoxys, C.sub.6 to C.sub.16 aryloxys, C.sub.7 to C.sub.18
alkylaryloxys, C.sub.1 to C.sub.12 fluoroalkyls, C.sub.6 to
C.sub.12 fluoroaryls, and C.sub.1 to C.sub.12 heteroatom-containing
hydrocarbons and substituted derivatives thereof; hydride, halogen
ions, C.sub.1 to C.sub.6 alkylcarboxylates, C.sub.1 to C.sub.6
fluorinated alkylcarboxylates, C.sub.6 to C.sub.12
arylcarboxylates, C.sub.7 to C.sub.18 alkylarylcarboxylates,
C.sub.1 to C.sub.6 fluoroalkyls, C.sub.2 to C.sub.6 fluoroalkenyls,
and C.sub.7 to C.sub.18 fluoroalkylaryls in yet a more particular
embodiment; hydride, chloride, fluoride, methyl, phenyl, phenoxy,
benzoxy, tosyl, fluoromethyls and fluorophenyls in yet a more
particular embodiment; C.sub.1 to C.sub.12 alkyls, C.sub.2 to
C.sub.12 alkenyls, C.sub.6 to C.sub.12 aryls, C.sub.7 to C.sub.20
alkylaryls, substituted C.sub.1 to C.sub.12 alkyls, substituted
C.sub.6 to C.sub.12 aryls, substituted C.sub.7 to C.sub.20
alkylaryls and C.sub.1 to C.sub.12 heteroatom-containing alkyls,
C.sub.1 to C.sub.12 heteroatom-containing aryls and C.sub.1 to
C.sub.12 heteroatom-containing alkylaryls in yet a more particular
embodiment; chloride, fluoride, C.sub.1 to C.sub.6 alkyls, C.sub.2
to C.sub.6 alkenyls, C.sub.7 to C.sub.18 alkylaryls, halogenated
C.sub.1 to C.sub.6 alkyls, halogenated C.sub.2 to C.sub.6 alkenyls,
and halogenated C.sub.7 to C.sub.18 alkylaryls in yet a more
particular embodiment; fluoride, methyl, ethyl, propyl, phenyl,
methylphenyl, dimethylphenyl, trimethylphenyl, fluoromethyls
(mono-, di- and trifluoromethyls) and fluorophenyls (mono-, di-,
tri-, tetra- and pentafluorophenyls) in yet a more particular
embodiment; and fluoride in yet a more particular embodiment.
[0023] Other non-limiting examples of leaving groups include
amines, phosphines, ethers, carboxylates, dienes, hydrocarbon
radicals having from 1 to 20 carbon atoms, fluorinated hydrocarbon
radicals (e.g., --C.sub.6F.sub.5 (pentafluorophenyl)), fluorinated
alkylcarboxylates (e.g., CF.sub.3C(O)O.sup.-), hydrides and halogen
ions and combinations thereof. Other examples of leaving groups
include alkyl groups such as cyclobutyl, cyclohexyl, methyl,
heptyl, tolyl, trifluoromethyl, tetramethylene, pentamethylene,
methylidene, methoxy, ethoxy, propoxy, phenoxy,
bis(N-methylanilide), dimethylamide, dimethylphosphide radicals and
the like. In one embodiment, two or more leaving groups form a part
of a fused ring or ring system.
[0024] It is also possible that L and A may be bridged to one
another. A bridged metallocene, for example may, be described by
the general formula: XCp.sup.ACp.sup.BMA.sub.n; wherein X is a
structural bridge, Cp.sup.A and Cp.sup.B each denote a
cyclopentadienyl group, each being the same or different and which
may be either substituted or unsubstituted, M is a transition metal
and A is an alkyl, hydrocarbyl or halogen group and n is an integer
between 0 and 4, and either 1 or 2 in a particular embodiment.
[0025] Non-limiting examples of bridging groups (X) include
divalent hydrocarbon groups containing at least one Group 13 to 16
atom, such as but not limited to at least one of a carbon, oxygen,
nitrogen, silicon, aluminum, boron, germanium and tin atom and
combinations thereof; wherein the heteroatom may also be C.sub.1 to
C.sub.12 alkyl or aryl substituted to satisfy neutral valency. The
bridging group may also contain substituent groups as defined above
including halogen radicals and iron. More particular non-limiting
examples of bridging group are represented by C.sub.1 to C.sub.6
alkylenes, substituted C.sub.1 to C.sub.6 alkylenes, oxygen,
sulfur, R.sub.2C.dbd., R.sub.2Si.dbd., --Si(R).sub.2Si(R.sub.2)--,
R.sub.2Ge.dbd., RP.dbd. (wherein ".dbd." represents two chemical
bonds), where R is independently selected from the group hydride,
hydrocarbyl, substituted hydrocarbyl, halocarbyl, substituted
halocarbyl, hydrocarbyl-substituted organometalloid,
halocarbyl-substituted organometalloid, disubstituted boron,
disubstituted Group 15 atoms, substituted Group 16 atoms, and
halogen radical; and wherein two or more Rs may be joined to form a
ring or ring system. In one embodiment, the bridged metallocene
catalyst component has two or more bridging groups (X).
[0026] Other non-limiting examples of bridging groups include
methylene, ethylene, ethylidene, propylidene, isopropylidene,
diphenylmethylene, 1,2-dimethylethylene, 1,2-diphenylethylene,
1,1,2,2-tetramethylethylene, dimethylsilyl, diethylsilyl,
methylethylsilyl, trifluoromethylbutylsilyl,
bis(trifluoromethyl)silyl, di(n-butyl)silyl, di(n-propyl)silyl,
di(i-propyl)silyl, di(n-hexyl)silyl, dicyclohexylsilyl,
diphenylsilyl, cyclohexylphenylsilyl, t-butylcyclohexylsilyl,
di(t-butylphenyl)silyl, di(p-tolyl)silyl and the corresponding
moieties, wherein the Si atom is replaced by a Ge or a C atom;
dimethylsilyl, diethylsilyl, dimethylgermyl and/or
diethylgermyl.
[0027] In another embodiment, the bridging group may also be
cyclic, and include 4 to 10 ring members or 5 to 7 ring members in
a more particular embodiment. The ring members may be selected from
the elements mentioned above, and/or from one or more of B, C, Si,
Ge, N and O in a particular embodiment. Non-limiting examples of
ring structures which may be present as or part of the bridging
moiety are cyclobutylidene, cyclopentylidene, cyclohexylidene,
cycloheptylidene, cyclooctylidene and the corresponding rings where
one or two carbon atoms are replaced by at least one of Si, Ge, N
and O, in particular, Si and Ge. The bonding arrangement between
the ring and the Cp groups may be cis-, trans-, or a combination
thereof.
[0028] The cyclic bridging groups may be saturated or unsaturated
and/or carry one or more substituents and/or be fused to one or
more other ring structures. If present, the one or more
substituents are selected from the group hydrocarbyl (e.g., alkyl
such as methyl) and halogen (e.g., F, Cl) in one embodiment. The
one or more Cp groups which the above cyclic bridging moieties may
optionally be fused to may be saturated or unsaturated and are
selected from the group of those having 4 to 10 ring members, more
particularly 5, 6 or 7 ring members (selected from the group of C,
N, O and S in a particular embodiment) such as, for example,
cyclopentyl, cyclohexyl and phenyl. Moreover, these ring structures
may themselves be fused such as, for example, in the case of a
naphthyl group. Moreover, these (optionally fused) ring structures
may carry one or more substituents. Illustrative, non-limiting
examples of these substituents are hydrocarbyl (particularly alkyl)
groups and halogen atoms.
[0029] In one embodiment, the metallocene catalyst includes CpFlu
Type catalysts (e.g., a metallocene incorporating a substituted Cp
fluorenyl ligand structure) represented by the following formula:
X(CpR.sup.1.sub.nR.sup.2.sub.m)(FluR.sup.3.sub.p) wherein Cp is a
cyclopentadienyl group, Fl is a fluorenyl group, X is a structural
bridge between Cp and F.sup.1, R.sup.1 is a substituent on the Cp,
n is 1 or 2, R.sup.2 is a substituent on the Cp at a position which
is proximal to the bridge, m is 1 or 2, each R.sup.3 is the same or
different and is a hydrocarbyl group having from 1 to 20 carbon
atoms with R.sup.3 being substituted on a nonproximal position on
the fluorenyl group and at least one other R.sup.3 being
substituted at an opposed nonproximal position on the fluorenyl
group and p is 2 or 4.
[0030] In yet another aspect, the metallocene catalyst includes
bridged mono-ligand metallocene compounds (e.g., mono
cyclopentadienyl catalyst components). In this embodiment, the at
least one metallocene catalyst component is a bridged
"half-sandwich" metallocene catalyst. In yet another aspect of the
invention, at least one metallocene catalyst component is an
unbridged "half sandwich" metallocene.
[0031] Described another way, the "half sandwich" metallocenes
above are described in U.S. Pat. No. 6,069,213, U.S. Pat. No.
5,026,798, U.S. Pat. No. 5,703,187, and U.S. Pat. No. 5,747,406,
including a dimer or oligomeric structure, such as disclosed in,
for example, U.S. Pat. No. 5,026,798 and U.S. Pat. No. 6,069,213,
which are incorporated by reference herein.
[0032] Non-limiting examples of metallocene catalyst components
consistent with the description herein include:
cyclopentadienylzirconiumA.sub.n, indenylzirconiumA.sub.n,
(1-methylindenyl)zirconiumA.sub.n,
(2-methylindenyl)zirconiumA.sub.n,
(1-propylindenyl)zirconiumA.sub.n,
(2-propylindenyl)zirconiumA.sub.n,
(1-butylindenyl)zirconiumA.sub.n, (2-butylindenyl)zirconiumA.sub.n,
methylcyclopentadienylzirconiumA.sub.n,
tetrahydroindenylzirconiumA.sub.n,
pentamethylcyclopentadienylzirconiumA.sub.n,
cyclopentadienylzirconiumA.sub.n,
pentamethylcyclopentadienyltitaniumA.sub.n,
tetramethylcyclopentyltitaniumA.sub.n,
(1,2,4-trimethylcyclopentadienyl)zirconiumA.sub.n,
dimethylsilyl(1,2,3,4-tetramethylcyclopentadienyl)
(cyclopentadienyl)zirconiumA.sub.n,
dimethylsilyl(1,2,3,4-tetramethylcyclopentadienyl)(1,2,3-trimethycyclopen-
tadienyl)zirconiumA.sub.n,
dimethylsilyl(1,2,3,4-tetramethylcyclopentadienyl)(1,2-dimethylcyclopenta-
dienyl)zirconiumA.sub.n,
dimethylsilyl(1,2,3,4-tetramethylcyclopentadienyl)(2-methylcyclopentadien-
yl)zirconiumA.sub.n,
dimethylsilylcyclopentadienylindenylzirconiumA.sub.n,
dimethylsilyl(2-methylindenyl)(fluorenyl)zirconiumA.sub.n,
diphenylsilyl(1,2,3,4-tetramethylcyclopentadienyl)(3-propylcyclopentadien-
yl)zirconiumA.sub.n, dimethylsilyl
(1,2,3,4-tetramethylcyclopentadienyl)
(3-t-butylcyclopentadienyl)zirconiumA.sub.n,
dimethylgermyl(1,2-dimethylcyclopentadienyl)(3-isopropylcyclopentadienyl)-
zirconiumA.sub.n,
di-methylsilyl(1,2,3,4-tetramethylcyclopentadienyl)(3-methylcyclopentadie-
nyl)zirconiumA.sub.n,
diphenylmethylidene(cyclopentadienyl)(9-fluorenyl)zirconiumA.sub.n,
diphenylmethylidenecyclopentadienylindenylzirconiumA.sub.n,
isopropylidenebiscyclopentadienylzirconiumA.sub.n,
isopropylidene(cyclopentadienyl)(9-fluorenyl)zirconiumA.sub.n,
isopropylidene(3-methylcyclopentadienyl)(9-fluorenyl)zirconiumA.sub.n,
ethylenebis(9-fluorenyl)zirconiumA.sub.n,
mesoethylenebis(1-indenyl)zirconiumA.sub.n,
ethylenebis(1-indenyl)zirconiumA.sub.n,
ethylenebis(2-methyl-1-indenyl)zirconiumA.sub.n,
ethylenebis(2-methyl-4,5,6,7-tetrahydro-1-indenyl)zirconiumA.sub.n,
ethylenebis(2-propyl-4,5,6,7-tetrahydro-1-indenyl)zirconiumA.sub.n,
ethylenebis(2-isopropyl-4,5,6,7-tetrahydro-1-indenyl)zirconiumA.sub.n,
ethylenebis(2-butyl-4,5,6,7-tetrahydro-1-indenyl)zirconiumA.sub.n,
ethylenebis(2-isobutyl-4,5,6,7-tetrahydro-1-indenyl)zirconiumA.sub.n,
dimethylsilyl(4,5,6,7-tetrahydro-1-indenyl)zirconiumA.sub.n,
diphenyl(4,5,6,7-tetrahydro-1-indenyl)zirconiumA.sub.n,
ethylenebis(4,5,6,7-tetrahydro-1-indenyl)zirconiumA.sub.n,
dimethylsilylbis(cyclopentadienyl)zirconiumA.sub.n,
dimethylsilylbis(9-fluorenyl)zirconiumA.sub.n,
dimethylsilylbis(1-indenyl)zirconiumA.sub.n,
dimethylsilylbis(2-methylindenyl)zirconiumA.sub.n,
dimethylsilylbis(2-propylindenyl)zirconiumA.sub.n,
dimethylsilylbis(2-butylindenyl)zirconiumA.sub.n,
diphenylsilylbis(2-methylindenyl)zirconiumA.sub.n,
diphenylsilylbis(2-propylindenyl)zirconiumA.sub.n,
diphenylsilylbis(2-butylindenyl)zirconiumA.sub.n,
dimethylgermylbis(2-methylindenyl)zirconiumA.sub.n,
dimethylsilylbistetrahydroindenylzirconiumA.sub.n,
dimethylsilylbistetramethylcyclopentadienylzirconiumA.sub.n,
dimethylsilyl(cyclopentadienyl)(9-fluorenyl)zirconiumA.sub.n,
diphenylsilyl(cyclopentadienyl)(9-fluorenyl)zirconiumA.sub.n,
diphenylsilylbisindenylzirconiumA.sub.n,
cyclotrimethylenesilyltetramethylcyclopentadienyl-cyclopentadienylzirconi-
umA.sub.n,
cyclotetramethylenesilyltetramethylcyclopentadienylcyclopentadi-
enylzirconiumA.sub.n,
cyclotrimethylenesilyl(tetramethylcyclopentadienyl)(2-methylindenyl)zirco-
niumA.sub.n,
cyclotrimethylenesilyl(tetramethylcyclopentadienyl)(3-methylcyclopentadie-
nyl)zirconiumA.sub.n,
cyclotrimethylenesilylbis(2-methylindenyl)zirconiumA.sub.n,
cyclotrimethylenesilyl(tetramethylcyclopentadienyl)(2,3,5-trimethylcyclop-
entadienyl)zirconiumA.sub.n,
cyclotrimethylenesilylbis(tetramethylcyclopentadienyl)zirconiumA.sub.n,
dimethylsilyl(tetra-methylcyclopentadieneyl)(N-tertbutylamido)titaniumA.s-
ub.n, biscyclopentadienylchromiumA.sub.n,
biscyclopentadienylzirconiumA.sub.n,
bis(nbutylcyclopentadienyl)zirconiumA.sub.n,
bis(n-do-decylcyclopentadienyl)zirconiumA.sub.n,
bisethylcyclopentadienylzirconiumA.sub.n,
bisisobutyl-cyclopentadienylzirconiumA.sub.n,
bisisopropylcyclopentadienylzirconiumA.sub.n,
bismethylcyclo-pentadienylzirconiumA.sub.n,
bisnoxtylcyclopentadienylzirconiumA.sub.n,
bis(n-pentylcyclo-pentadienyl)zirconiumA.sub.n,
bis(n-propylcyclopentadienyl)zirconiumA.sub.n,
bistrimethyl-silylcyclopentadienylzirconiumA.sub.n,
bis(1,3-bis(trimethylsilyl)cyclopentadienyl)zirconiumA.sub.n,
bis(1-ethyl-2-methylcyclopentadienyl)zirconiumA.sub.n,
bis(1-ethyl-3-methylcyclopenta-dienyl)zirconiumA.sub.n,
bispentamethylcyclopentadienylzirconiumA.sub.n,
bispentamethylcyclopentadienylzirconiumA.sub.n,
bis(1-propyl-3-methylcyclopentadienyl)zirconiumA.sub.n,
bis(1-nbutyl-3-methylcyclopentadienyl)zirconiumA.sub.n,
bis(1-isobutyl-3-methylcyclopentadienyl)zirconiumA.sub.n,
bis(1-propyl-3-butylcyclopentadienyl)zirconiumA.sub.n,
bis(1,3-n-butylcyclopentadienyl)zirconiumA.sub.n,
bis(4,7-dimethylindenyl)zirconiumA.sub.n,
bisindenylzirconiumA.sub.n, bis(2-methylindenyl)zirconiumA.sub.n,
cyclopentadienylindenylzirconiumA.sub.n,
bis(n-propylcyclopentadienyl)hafniumA.sub.n,
bis(n-butylcyclopentadienyl)hafniumA.sub.n,
bis(n-pentylcyclopentadienyl)hafniumA.sub.n,
(n-propylcyclopentadienyl)(n-butylcyclopentadienyl)hafniumA.sub.n,
bis[(2-trimethylsilylethyl)cyclopentadienyl]hafniumA.sub.n,
bis(trimethylsilylcyclopentadienyl)hafniumA.sub.n,
bis(2-n-propylindenyl)hafniumA.sub.n,
bis(2-n-butylindenyl)hafniumA.sub.n,
dimethylsilylbis(n-propylcyclopentadienyl)hafniumA.sub.n,
dimethylsilylbis(n-butylcyclopentadienyl)hafniumA.sub.n,
bis(9-n-propylfluorenyl)hafniumA.sub.n,
bis(9-n-butylfluorenyl)hafniumA.sub.n,
(9-npropylfluorenyl)(2-n-propylindenyl)hafniumA.sub.n,
bis(1-n-propyl-2-methylcyclopentadienyl)hafniumA.sub.n,
(n-propylcyclopentadienyl)(1-n-propyl-3-n-butylcyclopentadienyl)hafniumA.-
sub.n,
dimethylsilyltetramethylcyclopentadienylcyclopropylamidotitaniumA.s-
ub.n,
dimethylsilyl-tetramethylcyclopentadienylcyclobutylamidotitaniumA.su-
b.n,
dimethylsilyltetramethylcyclopentadienylcyclopentylamidotitaniumA.sub-
.n,
dimethylsilyltetramethylcyclopentadienylcyclohexylamidotitaniumA.sub.n-
,
dimethylsilyltetramethylcyclopentadienylcycloheptylamidotitaniumA.sub.n,
dimethylsilyltetramethylcyclopentadienylcyclooctylamidotitaniumA.sub.n,
dimethylsilyltetramethylcyclopentadienylcyclononylamidotitaniumA.sub.n,
dimethylsilyltetramethylcyclopentadienylcyclodecylamidotitaniumA.sub.n,
dimethylsilyltetramethylcyclopentadienylcycloundecylamidotitaniumA.sub.n,
dimethylsilyltetramethylcyclopentadienylcyclododecylamidotitaniumA.sub.n,
dimethylsilyltetramethylcyclopentadienyl(sec-butylamido)titaniumA.sub.n,
dimethylsilyl(tetramethylcyclopentadienyl)(n-octylamido)titaniumA.sub.n,
dimethylsilyl(tetramethylcyclopentadienyl)(n-decylamido)titaniumA.sub.n,
dimethylsilyl(tetramethylcyclopentadienyl)(n-octadecylamido)titaniumA.sub-
.n,
methylphenylsilyltetramethylcyclopentadienylcyclopropylamidotitaniumA.-
sub.n,
methylphenylsilyltetramethylcyclopentadienylcyclobutylamidotitanium-
A.sub.n,
methylphenylsilyltetramethylcyclopentadienylcyclopentylamidotitan-
iumA.sub.n,
methylphenylsilyltetramethylcyclopentadienylcyclohexylamidotitaniumA.sub.-
n,
methylphenylsilyltetramethylcyclopentadienylcycloheptylamidotitaniumA.s-
ub.n,
methylphenylsilyltetramethylcyclopentadienylcyclooctylamidotitaniumA-
.sub.n,
methylphenylsilyltetramethylcyclopentadienylcyclononylamidotitaniu-
mA.sub.n,
methylphenylsilyltetramethylcyclopentadienylcyclodecylamidotitan-
iumA.sub.n,
methylphenylsilyltetramethylcyclopentadienylcycloundecylamidotitaniumA.su-
b.n,
methylphenylsilyltetramethylcyclopentadienylcyclododecylamidotitanium-
A.sub.n,
methylphenylsilyl(tetramethylcyclopentadienyl)(sec-butylamido)tit-
aniumA.sub.n,
methylphenylsilyl(tetramethylcyclopentadienyl)(n-octylamido)titaniumA.sub-
.n,
methylphenylsilyl(tetramethylcyclopentadienyl)(n-decylamido)titaniumA.-
sub.n,
methylphenylsilyl(tetramethylcyclopentadienyl)(n-octadecylamido)tit-
aniumA.sub.n,
diphenylsilyltetramethylcyclopentadienylcyclopropylamidotitaniumA.sub.n,
diphenylsilyltetramethylcyclopentadienylcyclobutylamidotitaniumA.sub.n,
diphenylsilyltetramethylcyclopentadienylcyclopentylamidotitaniumA.sub.n,
diphenylsilyltetramethylcyclopentadienylcyclohexylamidotitaniumA.sub.n,
diphenylsilyltetramethylcyclopentadienylcycloheptylamidotitaniumA.sub.n,
diphenylsilyltetramethylcyclopentadienylcyclooctylamidotitaniumA.sub.n,
diphenylsilyltetramethylcyclopentadienylcyclononylamidotitaniumA.sub.n,
diphenylsilyltetramethylcyclopentadienylcyclodecylamidotitaniumA.sub.n,
diphenylsilyltetramethylcyclopentadienylcycloundecylamidotitaniumA.sub.n,
diphenylsilyltetramethylcyclopentadienylcyclododecylamidotitaniumA.sub.n,
diphenylsilyl(tetramethylcyclopentadienyl)(sec-butylamido)titaniumA.sub.n-
,
diphenylsilyl(tetramethylcyclopentadienyl)(n-octylamido)titaniumA.sub.n,
diphenylsilyl(tetramethyleyclopentadienyl)(n-decylamido)titaniumA.sub.n,
diphenylsilyl(tetramethylcyclopentadienyl)(n-octadecylamido)titaniumA.sub-
.n and derivatives thereof.
[0033] As used herein, the term "metallocene activator" is defined
to be any compound or combination of compounds, supported or
unsupported, which may activate a single-site catalyst compound
(e.g., metallocenes, Group 15 containing catalysts, etc.)
Typically, this involves the abstraction of at least one leaving
group (A group in the formulas/structures above, for example) from
the metal center of the catalyst component. The catalyst components
of the present invention are thus activated towards olefin
polymerization using such activators. Embodiments of such
activators include Lewis acids such as cyclic or oligomeric
polyhydrocarbylaluminum oxides and so called non-coordinating ionic
activators ("NCA"), alternately, "ionizing activators" or
"stoichiometric activators", or any other compound that may convert
a neutral metallocene catalyst component to a metallocene cation
that is active with respect to olefin polymerization.
[0034] More particularly, it is within the scope of this invention
to use Lewis acids such as alumoxane (e.g., "MAO"), modified
alumoxane (e.g., "TIBAO"), and alkylaluminum compounds as
activators, to activate desirable metallocenes described herein.
MAO and other aluminum-based activators are well known in the art.
Non-limiting examples of aluminum alkyl compounds which may be
utilized as activators for the catalysts described herein include
trimethylaluminum, triethylaluminum, triisobutylaluminum,
tri-n-hexylaluminum, tri-n-octylaluminum and the like.
[0035] Ionizing activators are well known in the art and are
described by, for example, Eugene You-Xian Chen & Tobin J.
Marks, Cocatalysts for Metal-Catalyzed Olefin Polymerization:
Activators, Activation Processes, and Structure-Activity
Relationships 100(4) CHEMICAL REVIEWS 1391-1434 (2000). Examples of
neutral ionizing activators include Group 13 tri-substituted
compounds, in particular, tri-substituted boron, tellurium,
aluminum, gallium and indium compounds, and mixtures thereof (e.g.,
tri(n-butyl)ammonium tetrakis(pentafluorophenyl)boron and/or
trisperfluorophenyl boron metalloid precursors). The three
substituent groups are each independently selected from alkyls,
alkenyls, halogen, substituted alkyls, aryls, arylhalides, alkoxy
and halides. In one embodiment, the three groups are independently
selected from the group of halogen, mono or multicyclic (including
halosubstituted) aryls, alkyls, and alkenyl compounds and mixtures
thereof. In another embodiment, the three groups are selected from
the group alkenyl groups having 1 to 20 carbon atoms, alkyl groups
having 1 to 20 carbon atoms, alkoxy groups having 1 to 20 carbon
atoms and aryl groups having 3 to 20 carbon atoms (including
substituted aryls), and combinations thereof. In yet another
embodiment, the three groups are selected from the group alkyls
having 1 to 4 carbon groups, phenyl, naphthyl and mixtures thereof.
In yet another embodiment, the three groups are selected from the
group highly halogenated alkyls having 1 to 4 carbon groups, highly
halogenated phenyls, and highly halogenated naphthyls and mixtures
thereof. By "highly halogenated", it is meant that at least 50
percent of the hydrogens are replaced by a halogen group selected
from fluorine, chlorine and bromine. In yet another embodiment, the
neutral stoichiometric activator is a tri-substituted Group 13
compound comprising highly fluorided aryl groups, the groups being
highly fluorided phenyl and highly fluorided naphthyl groups.
[0036] Illustrative, not limiting examples of ionic ionizing
activators include trialkylsubstituted ammonium salts such as
triethylammoniumtetraphenylboron,
tripropylammoniumtetraphenylboron,
tri(n-butyl)ammoniumtetraphenylboron,
trimethylammoniumtetra(p-tolyl)boron,
trimethylammoniumtetra(o-tolyl)boron,
tributylammoniumtetra(pentafluorophenyl)boron,
tripropylammoniumtetra(o,p-dimethylphenyl)boron,
tributylammoniumtetra(m,m-dimethylphenyl)boron,
tributylammoniumtetra(p-tri-fluoromethylphenyl)boron,
tributylammoniumtetra(pentafluorophenyl)boron,
tri(n-butyl)ammoniumtetra(o-tolyl)boron and the like;
N,N-dialkylanilinium salts such as
N,N-dimethylaniliniumtetraphenylboron,
N,N-diethylaniliniumtetraphenylboron,
N,N-2,4,6-pentamethylaniliniumtetraphenylboron and the like;
dialkyl ammonium salts such as
diisopropylammoniumtetrapentafluorophenylboron,
dicyclohexylammoniumtetraphenylboron and the like; triaryl
phosphonium salts such as triphenylphosphoniumtetraphenylboron,
trimethylphenylphosphoniumtetraphenylboron,
tridimethylphenylphosphoniumtetraphenylboron and the like, and
their aluminum equivalents.
[0037] In yet another embodiment, an alkylaluminum may be used in
conjunction with a heterocyclic compound. The ring of the
heterocyclic compound may include at least one nitrogen, oxygen,
and/or sulfur atom, and includes at least one nitrogen atom in one
embodiment. The heterocyclic compound includes 4 or more ring
members in one embodiment, and 5 or more ring members in another
embodiment.
[0038] The heterocyclic compound for use as an activator with an
alkylaluminum may be unsubstituted or substituted with one or a
combination of substituent groups. Examples of suitable
substituents include halogen, alkyl, alkenyl or alkynyl radicals,
cycloalkyl radicals, aryl radicals, aryl substituted alkyl
radicals, acyl radicals, aroyl radicals, alkoxy radicals, aryloxy
radicals, alkylthio radicals, dialkylamino radicals, alkoxycarbonyl
radicals, aryloxycarbonyl radicals, carbomoyl radicals, alkyl- or
dialkyl-carbamoyl radicals, acyloxy radicals, acylamino radicals,
aroylamino radicals, straight, branched or cyclic, alkylene
radicals, or any combination thereof. The substituents groups may
also be substituted with halogens, particularly fluorine or
bromine, or heteroatoms or the like.
[0039] Non-limiting examples of hydrocarbon substituents include
methyl, ethyl, propyl, butyl, pentyl, hexyl, cyclopentyl,
cyclohexyl, benzyl or phenyl groups and the like, including all
their isomers, for example tertiary butyl, isopropyl, and the like.
Other examples of substituents include fluoromethyl, fluoroethyl,
difluoroethyl, iodopropyl, bromohexyl or chlorobenzyl.
[0040] In one embodiment, the heterocyclic compound is
unsubstituted. In another embodiment one or more positions on the
heterocyclic compound are substituted with a halogen atom or a
halogen atom containing group, for example a halogenated aryl
group. In one embodiment the halogen is selected from the group
consisting of chlorine, bromine and fluorine, and selected from the
group consisting of fluorine and bromine in another embodiment, and
the halogen is fluorine in yet another embodiment.
[0041] Non-limiting examples of heterocyclic compounds utilized in
the activator of the invention include substituted and
unsubstituted pyrroles, imidazoles, pyrazoles, pyrrolines,
pyrrolidines, purines, carbazoles, and indoles, phenyl indoles,
2,5,-dimethylpyrroles, 3-pentafluorophenylpyrrole,
4,5,6,7-tetrafluoroindole or 3,4-difluoropyrroles.
[0042] In one embodiment, the heterocyclic compound described above
is combined with an alkyl aluminum or an alumoxane to yield an
activator compound which, upon reaction with a catalyst component,
for example a metallocene, produces an active polymerization
catalyst. Non-limiting examples of alkylaluminums include
trimethylaluminum, triethylaluminum, triisobutylaluminum,
tri-n-hexylaluminum, tri-n-octylaluminum, tri-iso-octylaluminum,
triphenylaluminum, and combinations thereof.
[0043] Other activators include those described in WO 98/07515 such
as tris (2,2', 2''-nonafluorobiphenyl) fluoroaluminate, which is
incorporated by reference herein. Combinations of activators are
also contemplated by the invention, for example, alumoxanes and
ionizing activators in combinations. Other activators include
aluminum/boron complexes, perchlorates, periodates and iodates
including their hydrates; lithium
(2,2'-bisphenyl-ditrimethylsilicate)-4T-HF; silylium salts in
combination with a non-coordinating compatible anion. Also, methods
of activation such as using radiation, electro-chemical oxidation,
and the like are also contemplated as activating methods for the
purposes of rendering the neutral metallocene-type catalyst
compound or precursor to a metallocene-type cation capable of
polymerizing olefins. Other activators or methods for activating a
metallocene-type catalyst compound are described in, for example,
U.S. Pat. Nos. 5,849,852, 5,859,653 and 5,869,723 and WO
98/32775.
[0044] In general, the activator and catalyst component(s) are
combined in mole ratios of activator to catalyst component from
1000:1 to 0.1:1 in one embodiment, and from 300:1 to 1:1 in a more
particular embodiment, and from 150:1 to 1:1 in yet a more
particular embodiment, and from 50:1 to 1:1 in yet a more
particular embodiment, and from 10:1 to 0.5:1 in yet a more
particular embodiment, and from 3:1 to 0.3:1 in yet a more
particular embodiment, wherein a desirable range may include any
combination of any upper mole ratio limit with any lower mole ratio
limit described herein. When the activator is a cyclic or
oligomeric poly(hydrocarbylaluminum oxide) (e.g., "MAO"), the mole
ratio of activator to catalyst component ranges from 2:1 to
100,000:1 in one embodiment, and from 10:1 to 10,000:1 in another
embodiment, and from 50:1 to 2,000:1 in a more particular
embodiment. When the activator is a neutral or ionic ionizing
activator such as a boron alkyl and the ionic salt of a boron
alkyl, the mole ratio of activator to catalyst component ranges
from 0.5:1 to 10:1 in one embodiment, and from 1:1 to 5:1 in yet a
more particular embodiment.
[0045] More particularly, the molar ratio of Al/metallocene-metal
(Al from MAO) ranges from 40 to 500 in one embodiment, ranges from
50 to 400 in another embodiment, ranges from 60 to 300 in yet
another embodiment, ranges from 70 to 200 in yet another
embodiment, ranges from 80 to 175 in yet another embodiment; and
ranges from 90 to 125 in yet another embodiment, wherein a
desirable molar ratio of Al(MAO) to metallocene-metal "M" may be
any combination of any upper limit with any lower limit described
herein.
[0046] The activators may or may not be associated with or bound to
a support, either in association with the catalyst component (e.g.,
metallocene) or separate from the catalyst component, such as
described by Gregory G. Hlatky, Heterogeneous Single-Site Catalysts
for Olefin Polymerization 100(4) CHEMICAL REVIEWS 1347-1374
(2000).
[0047] Metallocene catalysts may be supported or unsupported.
Typical support materials may include talc, inorganic oxides, clays
and clay minerals, ion-exchanged layered compounds, diatomaceous
earth compounds, zeolites or a resinous support material, such as a
polyolefin.
[0048] Specific inorganic oxides include silica, alumina, magnesia,
titania and zirconia, for example. The inorganic oxides used as
support materials may have an average particle size of from 30
microns to 600 microns, or from 30 microns to 100 microns, a
surface area of from 50 m.sup.2/g to 1,000 m.sup.2/g, or from 100
m.sup.2/g to 400 m.sup.2/g, a pore volume of from 0.5 cc/g to 3.5
cc/g, or from 0.5 cc/g to 2 cc/g.
[0049] Desirable methods for supporting metallocene ionic catalysts
are described in U.S. Pat. Nos. 5,643,847; 6,844,480 and 6,228,795,
which are incorporated by reference herein. The methods generally
include reacting neutral anion precursors that are sufficiently
strong Lewis acids with the hydroxyl reactive functionalities
present on the silica surface such that the Lewis acid becomes
covalently bound.
[0050] When the activator for the metallocene supported catalyst
composition is a NCA, desirably the NCA is first added to the
support composition followed by the addition of the metallocene
catalyst. When the activator is MAO, desirably the MAO and
metallocene catalyst are dissolved together in solution. The
support is then contacted with the MAO/metallocene catalyst
solution. Other methods and order of addition will be apparent to
those skilled in the art.
[0051] In one embodiment the catalyst is a racemic
M.sub.2Si(2M-PhInd).sub.2ZrCl.sub.2 on 0.7/1 MAO on P10 silica,
where M is a transition metal selected from Groups 4, 5 or 6; Ph is
phenyl; and Ind is indenyl. MAO is, as noted hereinabove,
methylalumoxane. Catalysts including racemic
M.sub.2Si(2M-4-PhInd).sub.2ZrCl.sub.2 on 0.7/1 MAO on P10 silica
are employed in another embodiment.
[0052] Preparation of metallocene catalysts in general may be found
described in, for example, U.S. Pat. No. 5,449,651, the disclosure
of which is incorporated herein by reference. In general, the
silica support material is first impregnated with the activator or
cocatalyst, such as methylalumoxane, in the given proportion, with
at least half of the activator or co-catalyst being disposed within
the internal pore volume of the silica. The silica is then
contacted with a dispersion of the metallocene catalyst in a
hydrocarbon, desirably aromatic, solvent. The catalyst dispersion
and silica which contains the activator or cocatalyst may then be
mixed together at a temperature of about 10.degree. C. or less, for
a period of time sufficient to enable the metallocene to become
reactively supported on the activator/cocatalyst-impregnated silica
particles. This mixing time may vary from a few minutes to several
hours. The supported catalyst is then recovered from the
hydrocarbon solvent and is generally washed. The washing may be
done in stages. An aromatic hydrocarbon solvent wash may be done
first. Following this, an optional second wash may be carried out
with a second aromatic hydrocarbon solvent to remove any
unsupported metallocene from the supported catalyst. Finally, a
paraffinic hydrocarbon wash may be done to remove remaining
aromatic solvent from the supported catalyst. The washing
procedures, like the mixing of the metallocene solvent dispersion
and activator/cocatalyst-containing silica, are desirably carried
out at the relatively low temperature of about 10.degree. C. or
less. Following washing the washed catalyst is desirably not dried,
with the result that it will contain a substantial residue of the
paraffinic hydrocarbon solvent.
[0053] Thereafter, the washed catalyst may be dispersed in a
viscous mineral oil having a viscosity substantially greater than
that of the paraffinic hydrocarbon solvent. Typically, the mineral
oil has a viscosity, at 40.degree. C., of at least about 65
centistokes as measured by ASTM D445. In contrast, the viscosity of
the paraffinic hydrocarbon solvent is usually less than about 1
centipoise at a temperature of about 10.degree. C. This viscosity
difference removes most of the paraffinic hydrocarbon solvent.
[0054] The final catalyst dispersion desirably has a significant
metal loading measured as weight percent in the dispersion. In one
embodiment this metal loading is from about 0.5 to about 6 weight
percent. In another embodiment this metal loading is from about 1
to about 3 weight percent, and in still another embodiment this
metal loading is about 2 weight percent in the dispersion.
[0055] Those skilled in the art will appreciate that a variety of
modifications in the above generalized catalyst preparation method
may be made without significantly altering the outcome. Therefore,
it will be understood that additional description of methods and
means of preparing the catalyst are outside of the scope of the
invention, and that it is only the identification of metallocenes
as catalysts that is necessarily described herein.
[0056] It will be kept in mind that the blend is a combination of a
metallocene catalyzed propylene random copolymer and a
polypropylene homopolymer, and that the homopolymer may be
catalyzed using any of the metallocene catalysts described
hereinabove, or a conventional Ziegler-Natta catalyst. In some
desirable embodiments the blend includes such a Ziegler-Natta
catalyzed homopolymer. Ziegler-type polyolefin catalysts, their
general methods of making, and subsequent use, are known in the
polymerization art.
[0057] Conventional Ziegler-Natta catalysts comprise a transition
metal compound generally represented by the formula: MR.sub.x where
M is a transition metal, R is a halogen or a hydrocarboxyl, and x
is the valence of the transition metal. Typically, M is a group IVB
metal such as titanium, chromium, or vanadium, and R is chlorine,
bromine, or an alkoxy group. The transition metal compound is
typically supported on an inert solid, e.g., magnesium chloride.
Examples of such catalyst systems are provided in U.S. Pat. Nos.
4,107,413; 4,294,721; 4,439,540; 4,114,319; 4,220,554; 4,460,701;
4,562,173; and 5,066,738, which are incorporated herein by
reference. Those skilled in the art will be familiar with
Ziegler-Natta catalysts and Ziegler-Natta polymerizations in
general.
[0058] In the case of the homopolymer it is, in one embodiment,
characterized as "highly isotactic" because it has a degree of
isotacticity of at least about 93 percent, desirably at least about
96 percent by weight. Unless noted to the contrary, the term "iPP
homopolymer" includes both pure iPP homopolymers and iPP
homopolymers containing less than about 1 weight percent of various
alpha olefins (including ethylene) by weight of the homopolymer.
One desirable polymer configuration for the random copolymers is
the isotactic configuration, with minimal presence of syndiotactic
or atactic polymer. Where ethylene is selected as the comonomer,
such isotactic C.sub.2-C.sub.3 random copolymers are essentially
insoluble in xylene, or have a minimal xylene solubles content, and
exhibit a relatively high degree of crystallinity, desirably from
about 10 to about 40 percent by weight. In the isotactic polymer
configuration C.sub.2-C.sub.3 random copolymers have a degree of
isotacticity that is desirably at least about 75 percent, more
desirably at least about 93 percent, and most desirably at least
about 96 percent. Examples of stereospecific polymer configurations
and propagation thereof may be found in U.S. Pat. No. 6,090,325,
the disclosure of which is incorporated herein by reference.
[0059] It is frequently desirable to mix or otherwise combine
certain additives with the PP homopolymer, prior to forming an end
use article. Selected additives may be suited to the particular
needs or desires of a user or maker, and various combinations of
the additives may be used. Because the PP homopolymers are
typically produced in the form of pellets or fluff, it is
frequently convenient to simply dry blend (for example, via tumble
blending) the additives with the pellets or fluff of the two
polymers, thereby accomplishing mixing of all components
simultaneously. Examples of apparatuses suitable for blending the
PP homopolymer base material with an additive include the
Henschel.TM. blender, the Banbury.TM. mixer, and any other
relatively low shear blending equipment. Solution blending may also
be done, where the polymers are melted together and the additives
are blended with them. Other blending or blending/melting protocols
may be employed. Combinations of such equipment may also be
effectively used.
[0060] Additives that are commonly employed are often combined into
commercial additive packages. These packages may include
stabilizers, which help to inhibit oxidation or thermal or
ultraviolet light degradation of the end use article. Examples of
suitable thermal stabilizers include, but are not limited to,
pentaerythritol tetrakis; tris(2,4-di-tert-butylphenyl)phosphite;
1,3,5-trimethyl-2,4,6-tris(3,5-di-tert-buytl-4-hydroxybenzyl)benzene;
octadecyl-3,5-di-tert-butyl-4-hydroxyhydrocinnamate; synthetic
hydrotalcite; and combinations thereof. Also frequently employed in
such packages are melt stabilizers (also called secondary
stabilizers), which help to prevent degradation during melt
processing. The melt stabilizers may be selected from a variety of
commercially available phosphate inhibitors and die lubricants,
including, for example, metal stearates, fluoropolymers, and their
combinations.
[0061] The amount of additives introduced to the inventive polymer
blend may be from about 0.0 percent to about 40.0 percent by weight
of the blend. Desirably the amount is from about 0.05 to about 30.0
percent by weight, more desirably from about 0.1 to 10 percent by
weight.
[0062] In general the processing properties of the blend used in
the inventive PP-derived articles of manufacture are improved.
These physical properties include, but are not necessarily limited
to, the blend's melt flow rate. Processing improvements may also
include a relatively high level of activity of the catalyst,
particularly for the metallocene catalyst.
[0063] For example, catalyst activity is a measure of the grams of
polymer produced per hour per gram of transition metal. The
activity of some effective metallocene catalysts useful to prepare
the homopolymers described herein may range from about 3500 to
about 6500 gig/h, at a reaction temperature from about 50 to about
70.degree. C. Fouling is a measure of polymer buildup during the
polymerization procedure. It may be measured using a standardized
technique from one polymerization run to another and is reported in
milligrams of polymer buildup per gram of polymer produced. The
fouling level of the described metallocene catalyzed polymerization
may range from about 5 to about 25 mg/g.
[0064] Another important property is the blend's melt flow rate
(MFR). This property may be determined using ASTM D1238, including
both procedure A (manual operation) and procedure B (automatically
timed flow). The MFR is inversely proportional to the average
length of a polymer chain. Thus, a higher MFR value is reflective
of a relatively short average polymer chain length. Because the
inventive compositions are blends of two main components, which may
be prepared individually or together in-situ, the compositions will
generally exhibit two distinct MFR's, with the homopolymer usually
exhibiting a melt flow rate that is significantly higher than that
of the copolymer. Each MFR may range from about 0.4 to about 100
g/10 min, desirably about 0.7 to about 30 g/10 min, using a 2.16 kg
load at 230.degree. C.
[0065] The term "bonding" as used herein refers to the application
of force or pressure to fuse molten or softened fibers together.
The term "thermal bonding" is used herein refers to the reheating
of staple fibers and the application of force or pressure to effect
the a melting (or softening) and fusing of such fibers. Operations
that employ drawing and fusing fibers together in a single or
simultaneous operation, or prior to any take-up roll (for example,
a godet) such as, for example, spunbonding are not consider to be a
thermal bonding operation, although the inventive fiber can have
the form of or result from a spunbonding operation and similar
fiber making operations.
[0066] The previously described compositions may be formed into
fibers using any suitable melt spinning procedure, such as the
conventionally known Fourne fiber spinning procedure known to those
skilled in the art of using a Fourne fiber spinning machine. The
fiber line can be operated in the fully oriented yarn (FOY) mode in
which extruded filaments are first melt drawn and then subsequently
mechanically drawn in at least one draw station. In operating the
Fourne line in the FOY mode, -polymer is passed from a hopper
through a heat exchanger where the polymer pellets are heated to a
suitable temperature for extrusion, about 180 to 280.degree. C.,
and then through a metering pump to a spin extruder. The fiber
preforms thus formed are cooled in air, then applied through one or
more godets to a spinning role which is operated at a desired
spinning rate, typically about 100-1500 meters per minute. The
thus-formed filaments are drawn off the spin role to the drawing
roller which is operated at a substantially-enhanced speed in order
to produce the drawn fiber. The draw speed normally will range from
about 1,000 to about 4,000 meters per minute and is operated
relative to the spinning godet to provide the desired draw ratio,
normally within the range of 1.1 to 5:1. For thermal bonding stable
fiber applications, low mechanical draw ratios are generally used.
For a further description of suitable fiber-spinning procedures for
use in the invention, reference is made to U.S. Pat. Nos.
5,908,594, 5,272,003, and 5,318,734, the disclosures of which are
incorporated herein by reference. In particular, the use of certain
metallocene catalysts, and particularly isospecific catalysts, may
result in structures that may be correlated with desirable fiber
characteristics, including strength and toughness.
[0067] The fiber line can be operated in the partially oriented
yarn (POY) mode in which extruded filaments are melt draw and
collected on a high speed winder or similar device. The POY
evaluation can be used to simulate the melt drawn characteristics
of the melt spinning portion of a spunbond process. In operating
the Fourne in the POY mode, polymer is processed similar to the FOY
mode except that filament is melt drawn and collected on a high
speed winder, up to 6000 meters/min.
[0068] Desirably, the POY fibers may exhibit sufficient strength
for handling and also may have a relatively high spinnability of
from about 2,000 to about 6,000 m/min. Compositions with high POY
spinnability rates are highly marketable in the spunbond fiber
industry.
[0069] A particular advantage of the invention is that the fibers
may also be used to prepare thermally bonded non-woven fabrics such
as those used for medical gowns and drapes, diapers and other
catamenial devices, filters, and the like. These fabrics can be
formed by carding thermally bonded staple fiber and thermally
bonding such web in a heated calendar roll. Or these fabrics can be
formed in a resin to fabric technology, such as the spunbond
process.
[0070] Fabrics in each case are prepared by thermal bonding at
temperatures ranging from about 220 to about 300.degree. C. In one
embodiment, the bonding temperature is 240. Particular improvements
are seen when the thermal bonding is carried out near the maximum
temperatures of a thermal bonding curve. At these temperatures the
machine direction tensile strength, in particular, is substantially
enhanced by the presence of the designated copolymer, in comparison
with non-woven fabrics that are identically prepared but include no
proportion of copolymer, i.e., they are only the homopolymer. In
some embodiments these fabrics may exhibit a tensile strength, at
basis weights of 10 and 17 grams/M.sup.2 (gsm) and a thermal
bonding temperature of about 280.degree. C., that are at least 5
percent higher than those attained in the homopolymer fabric.
Particularly at the higher basis weight and same thermal bonding
temperature, the tensile strength may be improved, in other
embodiments, by at least 10 percent. In still other embodiments,
the tensile strength may be improved by 20 percent or more. In
addition, the designated copolymer renders a nonwoven with improved
hand, softness, or drape. The low atactic polypropylene levels of
the designated copolymer results in a composition with low fuming.
Compositions with a balance of improved thermal bonded fabric
strengths, softness, and good processability offer advantages
especially for thermally bonded spunbond applications. Such
processes are disclosed in U.S. Pat. Nos. 3,825,379; 4,813,864;
4,405,297; 4,208,366; 4,334,340; 5,652,051; 5,714,256; 5,726,103;
6,224,977; 6,235,664; and 6,482,896, all hereby incorporated by
reference.
[0071] The invention having been generally described, the following
examples are given as particular embodiments of the invention and
to demonstrate the practice and advantages thereof. It is
understood that the examples are given by way of illustration and
are not intended to limit the specification or the claims to follow
in any manner.
EXAMPLES
Examples 1-6
[0072] Fibers are prepared for comparative purposes. They are
identified as those prepared from a Ziegler-Natta homopolymer
polypropylene alone, having a melt flow rate of 33 g/min
[comparative examples, denoted Examples 1 and 2], and those that
comprise either (1) 95 percent by weight of the same Ziegler-Natta
homopolymer polypropylene and 5 percent by weight of a metallocene
catalyzed propylene-ethylene copolymer, wherein the ethylene is
present in an amount of about 6 percent by weight of the copolymer
[inventive examples, denoted Examples 3 and 4]; or (2) 90 percent
by weight of the same Ziegler-Natta homopolymer polypropylene and
10 percent by weight of the metallocene catalyzed
propylene-ethylene copolymer [inventive examples, denoted Examples
5 and 6]. The copolymer employed has a melt flow rate of 9
g/min.
[0073] The homopolymer resin, and each of the resin blends, are
each processed at a melt temperature of 220.degree. C. through a
Nordson-design spunbond line fitted with a Hills R&D spunbond
die. The processing rate is 0.6 gram/minute/hole. The spunbond line
is 1.1 meter in width and is operated in a single beam mode.
Attenuation air pressure is slightly adjusted for each resin to
produce fiber at the target size of 1.5 denier/filament.
[0074] Following fiber preparation, the fibers are thermally bonded
at a temperature ranging from 250 to 300.degree. F. to form fabrics
at both 10 and 17 grams per square meter (gsm) basis weights. A two
inch strip is cut from the fabric made at each condition for
purposes of tensile strength and elongation testing in both the
machine direction and cross direction.
[0075] Tables 1-6 show the results of testing. Tables 1 and 2 show
the results for fabrics prepared at 10 and 17 gsm for the
polypropylene polymer alone, i.e., Examples 1 and 2, and are thus
comparative results. Tables 3 and 4 show the inventive compositions
at 10 and 17 gsm, where the copolymer is present in the blend in an
amount of 5 weight percent [Examples 3 and 4]. Tables 5 and 6 show
another inventive composition at 10 and 17 gsm, where the copolymer
is present in the blend in an amount of 10 weight percent [Examples
5 and 6]. TABLE-US-00001 TABLE 1 Homopolymer alone* Machine
Direction Cross Direction Tensile-max Elongation Tensile-max
Elongation Temp lbf % lbf % 250 1.7 25 0.9 25 260 3.3 26 1.0 27 270
2.8 27 1.5 30 280 3.2 30 2.1 41 290 3.7 31 2.4 42 300 4.6 32 2.5 38
*not an example of the invention; at 10 gsm
[0076] TABLE-US-00002 TABLE 2 Homopolymer alone* Machine Direction
Cross Direction Tensile-max Elongation Tensile-max Elongation Temp
lbf % lbf % 250 3.3 15 1.6 19 260 4.2 18 2.2 24 5.0 5.0 26 2.4 25
280 6.6 33 3.9 32 290 6.9 38 5.0 45 300 7.7 32 4.9 40 *not an
example of the invention; at 17 gsm
[0077] TABLE-US-00003 TABLE 3 95% homopolymer/5% copolymer blend
Machine Direction Cross Direction Tensile-max Elongation
Tensile-max Elongation Temp lbf % lbf % 250 2.2 19 1.1 27 260 2.8
27 1.1 27 270 4.0 29 1.6 35 280 4.8 38 1.7 36 290 4.0 37 2.1 40 300
4.8 31 2.5 43 *at 10 gsm
[0078] TABLE-US-00004 TABLE 4 95% homopolymer/5% copolymer blend*
Machine Direction Cross Direction Tensile-max Elongation
Tensile-max Elongation Temp lbf % lbf % 250 3.4 17 1.8 26 260 4.3
24 2.0 22 270 4.8 25 2.5 30 280 8.0 40 3.7 36 290 8.5 39 4.6 40 300
8.4 39 4.7 39 *at 17 gsm
[0079] TABLE-US-00005 TABLE 5 90% homopolymer/10% copolymer blend*
Machine Direction Cross Direction Tensile-max Elongation
Tensile-max Elongation Temp lbf % lbf % 250 2.4 22 0.9 26 260 2.5
22 1.2 37 270 2.9 27 1.2 29 280 3.5 32 2.2 39 *at 10 gsm
[0080] TABLE-US-00006 TABLE 6 90% homopolymer/10 percent copolymer
blend* Machine Direction Cross Direction Tensile-max Elongation
Tensile-max Elongation Temp lbf % lbf % 250 -- -- -- -- 260 4.5 21
1.4 22 270 4.7 19 2.3 28 280 8.1 37 4.0 40 *at 17 gsm -- indicates
no data taken
* * * * *