U.S. patent application number 11/048575 was filed with the patent office on 2005-06-16 for elastic substantially linear olefin polymers.
Invention is credited to Chum, Pak-Wing Steve, Knight, George W., Lai, Shih-Yaw, Stevens, James C., Wilson, John R..
Application Number | 20050131170 11/048575 |
Document ID | / |
Family ID | 26721538 |
Filed Date | 2005-06-16 |
United States Patent
Application |
20050131170 |
Kind Code |
A1 |
Lai, Shih-Yaw ; et
al. |
June 16, 2005 |
Elastic substantially linear olefin polymers
Abstract
Substantially linear olefin polymers having a melt flow ratio,
I.sub.10/I.sub.2, .gtoreq.5.63, a molecular weight distribution,
M.sub.w/M.sub.n, defined by the equation:
M.sub.w/M.sub.n.ltoreq.(I.sub.1- 0/I.sub.2)-4.63, and a critical
shear stress at onset of gross melt fracture of greater than about
4.times.10.sup.6 dyne/cm.sup.2 and their method of manufacture are
disclosed. The substantially linear olefin polymers preferably have
at least about 0.01 long chain branches/1000 carbons and a
molecular weight distribution from about 1.5 to about 2.5. The new
polymers have improved processability over conventional olefin
polymers and are useful in producing fabricated articles such as
fibers, films, and molded parts.
Inventors: |
Lai, Shih-Yaw; (Sugar Land,
TX) ; Wilson, John R.; (Richwood, TX) ;
Knight, George W.; (Lake Jackson, TX) ; Stevens,
James C.; (Midland, MI) ; Chum, Pak-Wing Steve;
(Lake Jackson, TX) |
Correspondence
Address: |
WHYTE HIRSCHBOECK DUDEK S.C.
555 EAST WELLS STREET
SUITE 1900
MILWAUKEE
WI
53202
US
|
Family ID: |
26721538 |
Appl. No.: |
11/048575 |
Filed: |
February 1, 2005 |
Related U.S. Patent Documents
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Application
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Filing Date |
Patent Number |
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11048575 |
Feb 1, 2005 |
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10727970 |
Dec 4, 2003 |
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6849704 |
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10727970 |
Dec 4, 2003 |
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10270212 |
Oct 11, 2002 |
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6737484 |
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10270212 |
Oct 11, 2002 |
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09884261 |
Jun 19, 2001 |
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6548611 |
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09884261 |
Jun 19, 2001 |
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08925827 |
Sep 5, 1997 |
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08925827 |
Sep 5, 1997 |
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08730766 |
Oct 16, 1996 |
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5665800 |
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08730766 |
Oct 16, 1996 |
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08606633 |
Feb 26, 1996 |
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08606633 |
Feb 26, 1996 |
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08433784 |
May 3, 1995 |
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08433784 |
May 3, 1995 |
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08370051 |
Jan 9, 1995 |
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5525695 |
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08370051 |
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08044426 |
Apr 7, 1993 |
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5380810 |
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08044426 |
Apr 7, 1993 |
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07776130 |
Oct 15, 1991 |
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Current U.S.
Class: |
526/126 ;
526/170; 526/348; 526/901 |
Current CPC
Class: |
C08F 10/00 20130101;
C08F 210/16 20130101; B29K 2995/0022 20130101; C08L 23/16 20130101;
B29C 48/08 20190201; C08L 23/04 20130101; C08F 210/16 20130101;
C08F 210/16 20130101; C08L 23/06 20130101; C08J 2323/08 20130101;
C08L 2314/06 20130101; C08F 210/16 20130101; C08F 10/02 20130101;
C08J 5/18 20130101; C08F 210/16 20130101; C08L 23/0815 20130101;
C08F 210/16 20130101; B32B 27/08 20130101; B29C 66/71 20130101;
C08L 23/16 20130101; C08F 110/00 20130101; C08F 2500/03 20130101;
C08F 110/02 20130101; C08F 2500/12 20130101; C08F 210/14 20130101;
C08F 2500/12 20130101; C08F 2500/26 20130101; C08F 2500/12
20130101; C08F 2500/03 20130101; C08F 2500/26 20130101; C08F
2500/19 20130101; C08F 4/6592 20130101; C08F 2500/19 20130101; C08F
210/14 20130101; C08F 2500/09 20130101; C08F 210/14 20130101; C08F
2500/09 20130101; C08F 216/14 20130101; C08F 2500/11 20130101; C08F
2500/12 20130101; C08F 4/6592 20130101; C08F 210/14 20130101; C08F
2500/08 20130101; C08F 2500/12 20130101; C08F 2500/05 20130101;
C08F 2500/09 20130101; C08F 2500/03 20130101; C08F 2500/11
20130101; C08F 2500/12 20130101; C08F 2500/17 20130101; C08F
2500/19 20130101; C08F 2500/03 20130101; C08F 210/14 20130101; C08F
2500/08 20130101; C08F 2500/19 20130101; C08F 2500/12 20130101;
C08F 2500/08 20130101; C08F 2500/09 20130101; C08F 2500/08
20130101; C08F 2500/09 20130101; C08F 2500/11 20130101; C08F
2500/11 20130101; C08F 2500/19 20130101; C08F 2500/19 20130101;
C08F 2500/11 20130101; C08F 2500/17 20130101; C08F 2500/19
20130101; C08L 2666/04 20130101; C08F 2500/03 20130101; C08F
2500/26 20130101; C08F 2500/12 20130101; C08F 2500/19 20130101;
C08L 2666/04 20130101; C08F 2500/03 20130101; C08F 2500/03
20130101; C08F 2500/11 20130101; B29C 65/00 20130101; C08F 210/14
20130101; C08F 2500/11 20130101; C08F 2500/12 20130101; B32B 27/322
20130101; C08F 210/16 20130101; B29C 65/8207 20130101; C08F 4/65912
20130101; B29C 65/8223 20130101; C08F 110/02 20130101; C08F 210/16
20130101; C08F 210/16 20130101; C08L 2205/02 20130101; C08F 210/16
20130101; B29C 66/71 20130101; C08F 210/16 20130101; C08L 23/02
20130101; C08F 110/02 20130101; C08F 110/02 20130101; Y10S 526/943
20130101; B29C 48/05 20190201; B29C 48/15 20190201; C08F 10/00
20130101; C08F 2500/03 20130101; B29C 48/00 20190201; C08F 2500/09
20130101; C08F 210/14 20130101; C08F 2500/12 20130101; C08F 210/14
20130101; C08F 2500/09 20130101; C08F 2500/17 20130101; C08L
2666/04 20130101; C08F 2500/07 20130101; C08F 2500/12 20130101;
C08F 2500/08 20130101; C08J 2303/08 20130101; C08F 4/65908
20130101; C08F 4/6592 20130101; C08L 23/04 20130101; C08G 83/003
20130101; C08L 23/0815 20130101; B29C 48/022 20190201; C08F 110/02
20130101 |
Class at
Publication: |
526/126 ;
526/901; 526/170; 526/348 |
International
Class: |
C08L 051/00 |
Claims
1-102. (canceled)
103. An olefin homopolymer, the polymer having: A. a melt flow
ratio, I.sub.10/I.sub.2, .gtoreq.5.63, B. a molecular weight
distribution, M.sub.w/M.sub.n, defined by the equation:
M.sub.w/M.sub.n.ltoreq.(I.sub.1- 0/I.sub.2)-4.63, and C. a critical
shear stress at onset of gross melt fracture greater than about
4.times.10.sup.6 dyne/cm.sup.2.
104. An olefin homopolymer, the polymer having: A. a melt flow
ratio, I.sub.10/I.sub.2, .gtoreq.5.63, and B. a molecular weight
distribution, M.sub.w/M.sub.n of from about 1.5 to about 2.5.
105. An olefin homopolymer, the polymer having: A. from about 0.01
to about 3 long chain branches/1000 carbons, and B. a critical
shear stress at onset of gross melt fracture of greater than about
4.times.10.sup.6 dyne/cm.sup.2.
Description
FIELD OF THE INVENTION
[0001] This invention relates to elastic substantially linear
olefin polymers having improved processability, e.g., low
susceptibility to melt fracture, even under high shear stress
extrusion conditions. Methods of manufacturing these polymers are
also disclosed.
BACKGROUND OF THE INVENTION
[0002] Molecular weight distribution (MWD), or polydispersity, is a
well known variable in polymers. The molecular weight distribution,
sometimes described as the ratio of weight average molecular weight
(M.sub.w) to number average molecular weight (M.sub.n) (i.e.,
M.sub.w/M.sub.n) can be measured directly, e.g., by gel permeation
chromatography techniques, or more routinely, by measuring
I.sub.10/I.sub.2 ratio, as described in ASTM D-1238. For linear
polyolefins, especially linear polyethylene it is well known that
as M.sub.w/M.sub.n increases, I.sub.10/I.sub.2 also increases.
[0003] John Dealy in "Melt Rheology and Its Role in Plastics
Processing" (Van Nostrand Reinhold, 1990) page 597 discloses that
ASTM D-1238 is employed with different loads in order to obtain an
estimate of the shear rate dependence of melt viscosity, which is
sensitive to weight average molecular weight (M.sub.w) and number
average molecular weight (M.sub.n).
[0004] Bersted in Journal of Applied Polymer Science Vol. 19, page
2167-2117 (1975) theorized the relationship between molecular
weight distribution and steady shear melt viscosity for linear
polymer systems. He also showed that the broader MWD material
exhibits a higher shear rate or shear stress dependency.
[0005] Ramamurthy in Journal of Rheology, 30(2), 337-357 (-1986),
and Moynihan, Baird and Ramanathan in Journal of Non-Newtonian
Fluid Mechanics, 36, 255-263 (1990), both disclose that the onset
of sharkskin (i.e., melt fracture) for linear low density
polyethylene (LLDPE) occurs at an apparent shear stress of
1-1.4.times.10.sup.6 dyne/cm.sup.2, which was observed to be
coincident with the change in slope of the flow curve. Ramamurthy
also discloses that the onset of surface melt fracture or of gross
melt fracture for high pressure low density polyethylene (HP-LDPE)
occurs at an apparent shear stress of about 0.13 MPa
(1.3.times.10.sup.6 dynes/cm.sup.2).
[0006] Kalika and Denn in Journal of Rheology, 31, 815-834 (1987)
confirmed the surface defects or sharkskin phenomena for LLDPE, but
the results of their work determined a critical shear stress of
2.3.times.10.sup.6 dyne/cm.sup.2, significantly higher than that
found by Ramamurthy and Moynihan et al.
[0007] International Patent Application (Publication No. WO
90/03414) published Apr. 5, 1990, discloses linear ethylene
interpolymer blends with narrow molecular weight distribution and
narrow short chain branching distributions (SCBDs). The melt
processibility of the interpolymer blends is controlled by blending
different molecular weight interpolymers having different narrow
molecular weight distributions and different SCSDs.
[0008] Exxon Chemical Company, in the Preprints of Polyolefins VII
International Conference, page 45-66, Feb. 24-27 1991, disclose
that the narrow molecular weight distribution (NMWD) resins
produced by their EXXPOL.TM. technology have higher melt viscosity
and lower melt strength than conventional Ziegler resins at the
same melt index. In a recent publication, Exxon Chemical Company
has also taught that NMWD polymers made using a single site
catalyst create the potential for melt fracture ("New Specialty
Linear Polymers (SLP) For Power Cables," by Monica Hendewerk and
Lawrence Spenadel; presented at IEEE meeting in Dallas, Tex.,
September, 1991).
[0009] Previously known narrow molecular weight distribution linear
polymers disadvantageously possessed low shear sensitivity or low
I.sub.10/I.sub.2 value, which limits the extrudability of such
polymers. Additionally, such polymers possessed low melt
elasticity, causing problems in melt fabrication such as film
forming processes or blow molding processes (e.g., sustaining a
bubble in the blown film process, or sag in the blow molding
process etc.). Finally, such resins also experienced melt fracture
surface properties at relatively low extrusion rates thereby
processing unacceptably.
SUMMARY OF THE INVENTION
[0010] We have now discovered a new family of substantially linear
olefin polymers which have many improved properties and a method of
their manufacture. The substantially linear olefin polymers have
(1) high melt elasticity and, (2) relatively narrow molecular
weight distributions with exceptionally good processibility while
maintaining good mechanical properties and (3) they do not melt
fracture over a broad range of shear stress conditions. These
properties are obtained without benefit of specific processing
additives. The new polymers can be successfully prepared in a
continuous polymerization process using constrained geometry
catalyst technology, especially when polymerized utilizing solution
process technology.
[0011] The improved properties of the polymers include improved
melt elasticity and processability in thermal forming processes
such as extrusion, blowing film, injection molding and
blowmolding.
[0012] Substantially linear polymers made according to the present
invention have the following novel properties:
[0013] a) a melt flow ratio, I.sub.10/I.sub.2, .gtoreq.5.63,
[0014] b) a molecular weight distribution, M.sub.w/M.sub.n, defined
by the equation:
M.sub.w/M.sub.n.ltoreq.(I.sub.10/I.sub.2)-4.63, and
[0015] c) a critical shear stress at onset of gross melt fracture
of greater than about 4.times.10.sup.6 dyne/cm.sup.2.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 is a schematic representation of a polymerization
process suitable for making the polymers of the present
invention.
[0017] FIG. 2 plots data describing the relationship between
I.sub.10/I.sub.2 and M.sub.w/M.sub.n for polymer Examples 5 and 6
of the invention, and from comparative examples 7-9.
[0018] FIG. 3 plots the shear stress versus shear rate for Example
5 and comparative example 7, described herein.
[0019] FIG. 4 plots the shear stress versus shear rate for Example
6 and comparative example 9, described herein.
[0020] FIG. 5 plots the heat seal strength versus heat seal
temperature of film made from Examples 10 and 12, and comparative
examples 11 and 13, described herein.
DETAILED DESCRIPTION OF THE INVENTION
[0021] Other properties of the substantially linear polymers
include:
[0022] a) a density from about 0.85 grams/cubic centimeter (g/cc)
to about 0.97 g/cc (tested in accordance with ASTM D-792), and
[0023] b) a melt index, MI, from about 0.01 grams/10 minutes to
about 1000 gram/10 minutes.
[0024] Preferably the melt flow ratio, I.sub.10/I.sub.2, is from
about 7 to about 20.
[0025] The molecular weight distribution (i.e., M.sub.w/M.sub.n) is
preferably less than about 5 especially less than about 3.5, and
most preferably from about 1.5 to about 2.5.
[0026] Throughout this disclosure, "melt index" or "I.sub.2" is
measured in accordance with ASTM D-1238 (190/2.16); "I.sub.10" is
measured in accordance with ASTM D-1238 (190/10).
[0027] The melt tension of these new polymers is also surprisingly
good, e.g., as high as about 2 grams or more, especially for
polymers which have a very narrow molecular weight distribution
(i.e., M.sub.w/M.sub.n from about 1.5 to about 2.5).
[0028] The substantially linear polymers of the present invention
can be homopolymers of C.sub.2-C.sub.20 olefins, such as ethylene,
propylene, 4methyl-1-pentene, etc., or they can be interpolymers of
ethylene with at least one C.sub.3-C.sub.20 .alpha.-olefin and/or
C.sub.2-C.sub.20 acetylenically unsaturated monomer and/or
C.sub.4-C.sub.18 diolefins. The substantially linear polymers of
the present invention can also be interpolymers of ethylene with at
least one of the above C.sub.3-C.sub.20 .alpha.-olefins, diolefins
and/or acetylenically unsaturated monomers in combination with
other unsaturated monomers.
[0029] Monomers usefully polymerized according to the present
invention include, for example, ethylenically unsaturated monomers,
acetylenic compounds, conjugated or nonconjugated dienes, polyenes,
carbon monoxide, etc. Preferred monomers include the C.sub.2-10
.alpha.-olefins especially ethylene, propylene, isobutylene,
1-butene, 1-hexene, 4-methyl-1-pentene, and 1-octene. Other
preferred monomers include styrene, halo- or alkyl substituted
styrenes, tetrafluoroethylene vinylbenzocyclobutane, 1,4-hexadiene,
and naphthenics (e.g., cyclo-pentene, cyclo-hexene and
cyclo-octene).
[0030] The term "substantially linear" polymers means that the
polymer backbone is either unsubstituted or substituted with up to
3 long chain branches/1000 carbons. Preferred polymers are
substituted with about 0.01 long chain branches/1000 carbons to
about 3 long chain branches/1000 carbons, more preferably from
about 0.01 long chain branches/1000 carbons to about 1 long chain
branches/1000 carbons, and especially from about 0.3 long chain
branches/1000 carbons to about 1 long chain branches/1000
carbons.
[0031] Long chain branching is defined herein as a chain length of
at least about 6 carbons, above which the length cannot be
distinguished using .sup.13C nuclear magnetic resonance
spectroscopy. The long chain branch can be as long as about the
same length as the length of the polymer back-bone.
[0032] Long chain branching is determined by using .sup.13C nuclear
magnetic resonance (NMR) spectroscopy and is quantified using the
method of Randall (Rev. Macromol. Chem. Phys., C29 (2&3), p.
285-297), the disclosure of which is incorporated herein by
reference.
[0033] "Melt tension" is measured by a specially designed pulley
transducer in conjunction with the melt indexer. Melt tension is
the load that the extrudate or filament exerts while passing over
the pulley at the standard speed of 30 rpm. The melt tension
measurement is similar to the "Melt Tension Tester" made by
Toyoseiki and is described by John Dealy in "Rheometers for Molten
Plastics", published by Van Nostrand Reinhold Co. (1982) on page
250-251.
[0034] The "rheological processing index" (PI) is the apparent
viscosity (in kpoise) of a polymer measured by a gas extrusion
rheometer (GER). The gas extrusion rheometer is described by M.
Shida, R. N. Shroff and L. V. Cancio in Polymer Engineering
Science, Vol. 71, no. 11, p. 770 (1977), and in "Rheoreters for
Molten Plastics" by John Dealy, published by Van Nostrand Reinhold
Co. (1982) on page 77, both publications of which are incorporated
by reference herein in their entirety. All GER experiments are
performed at a temperature of 190.degree. C., at nitrogen pressures
between 5250 to 500 psig using a 0.0296 inch diameter, 20:1
L/D.multidot.die. An apparent shear stress vs. apparent shear rate
plot is used to identify the melt fracture phenomena. According to
Ramamurthy in Journal of Rheology, 30(2), 317-357, 1986, above a
certain critical flow rate, the observed extrudate irregularities
may be broadly classified into two main types: surface melt
fracture and gross melt fracture.
[0035] Surface melt fracture occurs under apparently steady flow
conditions and ranges in detail from loss of specular gloss to the
more severe form of "sharkskin". Gross melt fracture occurs at
unsteady flow conditions and ranges in detail from regular
(alternating rough and smooth, helical, etc.) to random
distortions. For commercial acceptability, (e.g., in blown film
products), surface defects should be minimal, if not absent. The
critical shear rate at onset of surface melt fracture (OSMF) and
onset of gross melt fracture (OGMF) will be used herein based on
the changes of surface roughness and configurations of the
extrudates extruded by a GER. Preferably, the critical shear stress
at the OGMF and the critical shear stress at the OSMF for the
substantially linear ethylene polymers described herein is greater
than about 4.times.10.sup.6dyne/cm.sup.2 and greater than about
2.8.times.10.sup.6 dyne/cm.sup.2, respectively.
[0036] For the polymers described herein, the PI is the apparent
viscosity (in Kpoise) of a material measured by GER at a
temperature of 190.degree. C., at nitrogen pressure of 2500 psig
using a 0.0296 inch diameter, 20:1 L/D die, or corresponding
apparent shear stress of 2.15.times.10.sup.6 dyne/cm.sup.2. The
novel polymers described herein preferably have a PI in the range
of about 0.01 kpoise to about 50 kpoise, preferably about 15 kpoise
or less.
[0037] The SCBDI (Short Chain Branch Distribution index) or CDBI
(Composition Distribution Branch Index) is defined as the weight
percent of the polymer molecules having a comonomer content within
50 percent of the median total molar comonomer content. The CDBI of
an polymer is readily calculated from data obtained from techniques
known in the art, such as, for example, temperature rising elution
fractionation (abbreviated herein as "TREF") as described, for
example, in Wild et al, Journal of Polymer Science, Poly. Phys.
Ed., Vol. 20, p. 44 (1982), or in U.S. Pat. No. 4,798,081, both
disclosures of which are incorporated herein by reference. The
SCIBDI or CDBI for the new polymers of the present invention is
preferably greater than about 30 percent, especially greater than
about 50 percent.
[0038] The most unique characteristic of the presently claimed
polymers is a highly unexpected flow property as shown in FIG. 2,
where the I.sub.10/I.sub.2 value is essentially independent of
polydispersity index (i.e. M.sub.w/M.sub.n). This is contrasted
with conventional polyethylene resins having rheological properties
such that as the polydispersity index increases, the
I.sub.10/I.sub.2 value also increases. Measurement of the
polydispersity index is done according to the following
technique:
[0039] The polymers are analyzed by gel permeation chromatography
(GPC) on a Waters 150C high temperature chromatographic unit
equipped with three linear mixed bed columns (Polymer Laboratories
(10 micron particle size)), operating at a system temperature of
140.degree. C. The solvent is 1,2,4-trichlorobenzene, from which
about 0.5% by weight solutions of the samples are prepared for
injection. The flow rate is 1.0 milliliter/minute and the injection
size is 100 microliters.
[0040] The molecular weight determination is deduced by using
narrow molecular weight distribution polystyrene standards (from
Polymer Laboratories) in conjunction with their elution volumes.
The equivalent polyethylene molecular weights are determined by
using appropriate Mark-Houwink coefficients for polyethylene and
polystyrene (as described by Williams and Word in Journal of
Polymer Science, Polymer Letters, Vol. 6, (621) 1968, incorporated
herein by reference) to derive the equation:
.sup.Mpolyethylene=.sup.(a)(Mpolystyrene).sup.b
[0041] In this equation, a=0.4316 and b=1.0. Weight average
molecular weight, M.sub.w, is calculated in the usual manner
according to the formula:
M.sub.w=(R)(w.sub.i)(M.sub.i)
[0042] where w.sub.i and M.sub.i are the weight fraction and
molecular weight respectively of the ith fraction eluting from the
GPC column.
[0043] Another highly unexpected characteristic of the polymers of
the present invention is their non-susceptibility to melt fracture
or the formation of extrudate defects during high pressure, high
speed extrusion. Preferably, polymers of the present invention do
not experience "sharkskin" or surface melt fracture during the GER
extrusion process even at an extrusion pressure of 5000 psi and
corresponding apparent stress of 4.3.times.10.sup.6 dyne/cm.sup.2.
In contrast, a conventional LLDPE experiences "sharkskin" or onset
of surface melt fracture (OSMF) at an apparent stress under
comparable conditions as low as 1.0-1.4.times.10.sup.6
dyne/cm.sup.2.
[0044] Improvements of melt elasticity and processibility over
conventional LLDPE resins with similar MI are most pronounced when
I.sub.2 is lower than about 3 grams/10 minutes. Improvements of
physical properties such as strength properties, heat seal
properties, and optical properties, over the conventional LLDPE
resins with similar MI, are most pronounced when I.sub.2 is lower
than about 100 grams/10 minutes. The substantially linear polymers
of the present invention have processibility similar to that of
High Pressure LDPE while possessing strength and other physical
properties similar to those of conventional LLDPE, without the
benefit of special adhesion promoters (e.g., processing additives
such as Viton.TM. fluoroelastomers made by E.I. DuPont de Nemours
& Company).
[0045] The improved melt elasticity and processibility of the
substantially linear polymers according to the present invention
result, it is believed, from their method of production. The
polymers may be produced via a continuous controlled polymerization
process using at least one reactor, but can also be produced using
multiple reactors (e.g., using a multiple reactor configuration as
described in U.S. Pat. No. 3,914,342, incorporated herein by
reference) at a polymerization temperature and pressure sufficient
to produce the interpolymers having the desired properties.
According to one embodiment of the present process, the polymers
are produced in a continuous process, as opposed to a batch
process. Preferably, the polymerization temperature is from about
20.degree. C. to about 250.degree. C., using constrained geometry
catalyst technology. If a narrow molecular weight distribution
polymer (M.sub.w/M.sub.n of from about 1.5 to about 2.5) having a
higher I.sub.10/I.sub.2 ratio (e.g. I.sub.10/I.sub.2 of about 7 or
more, preferably at least about 8, especially at least about 9) is
desired, the ethylene concentration in the reactor is preferably
not more than about 8 percent by weight of the reactor contents,
especially not more than about 4 percent by weight of the reactor
contents. Preferably, the polymerization is performed in a solution
polymerization process. Generally, manipulation or I.sub.10/I.sub.2
while holding M.sub.w/M.sub.n relatively low for producing the
novel polymers described herein is a function of reactor
temperature and/or ethylene concentration. Reduced ethylene
concentration and higher temperature generally produces higher
I.sub.10/I.sub.2.
[0046] Suitable catalyses for use herein preferably include
constrained geometry catalysts as disclosed in U.S. application
Ser. Nos.: 545,403, filed Jul. 3, 1990; 758,654, filed Sep. 12,
1991; 758,660, filed Sep. 12, 1991, and 720,041, filed Jun. 24,
1991, the teachings of all of which are incorporated herein by
reference.
[0047] The monocyclopentadienyl transition metal olefin
polymerization catalysts taught in U.S. Pat. No. 5,026,798, the
teachings of which are incorporated herein by reference, are also
suitable for use in preparing the polymers of the present
invention.
[0048] The foregoing catalysts may be further described as
comprising a metal coordination complex comprising a metal of
groups 3-10 or the Lanthanide series of the Periodic Table of the
Elements and a delocalized n-bonded moiety substituted with a
constrain-inducing moiety, said complex having a constrained
geometry about the metal atom such that the angle at the metal
between the centroid of the delocalized, substituted n-bonded
moiety and the center of at least one remaining substituent is less
than such angle in a similar complex containing a similar n-bonded
moiety lacking in such constrain-inducing substituent, and provided
further that for such complexes comprising more than one
delocalized, substituted n-bonded moiety, only one thereof for each
metal atom of the complex is a cyclic, delocalized, substituted
n-bonded moiety. The catalyst further comprises an activating
cocatalyst.
[0049] Preferred catalyst complexes correspond to the formula:
1
[0050] wherein:
[0051] M is a metal of group 3-10, or the Lanthanide series of the
Periodic Table of the Elements;
[0052] Cp* is a cyclopentadienyl or substituted cyclopentadienyl
group bound in an .eta..sup.5 bonding mode to M;
[0053] Z is a moiety comprising boron, or a member of group 14 of
the Periodic Table of the Elements, and optionally sulfur or
oxygen, said moiety having up to 20 non-hydrogen atoms, and
optionally Cp* and Z together form a fused ring system;
[0054] X independently each occurrence is an anionic ligand group
or neutral Lewis base ligand group having up to 30 non-hydrogen
atoms;
[0055] n is 0, 1, 2, 3, or 4 and is 2 less than the valence of M;
and
[0056] Y is an anionic or nonanionic ligand group bonded to Z and N
comprising nitrogen, phosphorus, oxygen or sulfur and having up to
20 non-hydrogen atoms, optionally Y and Z together form a fused
ring system.
[0057] More preferably still, such complexes correspond to the
formula: 2
[0058] wherein R' each occurrence is independently selected from
the group consisting of hydrogen, alkyl, aryl, silyl, germyl,
cyano, halo and combinations thereof having up to 20 non-hydrogen
atoms;
[0059] X each occurrence independently is selected from the group
consisting of hydride, halo, alkyl, aryl, silyl, germyl, aryloxy,
alkoxy, amide, siloxy, neutral Lewis base ligands and combinations
thereof having up to 20 non-hydrogen atoms;
[0060] Y is --O--, --S--, --NR*--, --PR*-- or a neutral two
electron donor ligand selected from the group consisting of OR*,
SR*, NR*.sub.2, or PR*.sub.2.
[0061] M is a previously defined; and
[0062] Z is SiR*.sub.2, CR*.sub.2, SiR*.sub.2SiR*.sub.2,
CR*.sub.2CR*.sub.2, CR*.dbd.CR*, CR*.sub.2SiR*.sub.2, GeR*.sub.2,
BR*, BR*.sub.2; wherein:
[0063] R* each occurrence is independently selected from the group
consisting of hydrogen, alkyl, aryl, silyl, halogenated alkyl,
halogenated aryl groups having up to 20 non-hydrogen atonst and
mixtures thereof, or two or more R* groups from Y, Z, or both Y and
Z form a fused ring system; and
[0064] n is 1 or 2.
[0065] It should be noted that whereas formula I and the following
formulas indicate a cyclic structure for the catalysts, when Y is a
neutral two electron donor ligand, the bond between H and Y is more
accurately referred to as a coordinate-covalent bond. Also, it
should be noted that the complex may exist as a dimer or higher
oligomer.
[0066] Further preferably, at least one of R*, Z, or R* is an
electron donating moiety. Thus, highly preferably Y is a nitrogen
or phosphorus containing group corresponding to the formula
--N(R"-- or --P(R")--, wherein R" is C.sub.1-10 alkyl or aryl, i.e.
an amido or phosphido group.
[0067] Most highly preferred complex compounds are amidosilane- or
amidoalkanediyl-compounds corresponding to the formula: 3
[0068] wherein:
[0069] M is titanium, zirconium or hafnium, bound in an .eta..sup.5
bonding mode to the cyclopentadienyl group;
[0070] R' each occurrence is independently selected from the group
consisting of hydrogen, silyl, alkyl, aryl and combinations thereof
having up to 10 carbon or silicon atoms;
[0071] E is silicon or carbon;
[0072] X independently each occurrence is hydride, halo, alkyl,
aryl, aryloxy or alkoxy of up to 10 carbons;
[0073] m is 1 or 2; and
[0074] n is 1 or 2.
[0075] Examples of the above most highly preferred metal
coordination compounds include compounds wherein the R' on the
amido group is methyl, ethyl, propyl, butyl, pentyl, hexyl,
(including isomers), norbornyl, benzyl, phenyl, etc.; the
cyclopentadienyl group is cyclopentadienyl, indenyl,
tetrahydroindenyl, fluorenyl, octahydrofluorenyl, etc.; R' on the
foregoing cyclopentadienyl groups each occurrence is hydrogen,
methyl, ethyl, propyl, butyl, pentyl, hexyl, (including isomers),
norbornyl, benzyl, phenyl, etc.; and X is chloro, bromo, iodo,
methyl, ethyl, propyl, butyl, pentyl, hexyl, (including isomers),
norbornyl, benzyl, phenyl, etc. Specific compounds include:
(tert-butylamido)
(tetramethyl-.eta..sup.5-cyclopentadienyl)-1,2-ethanediylzirconium
dichloride,
(tert-butylamido)(tetra-methyl-.eta..sup.5-cyclopentadienyl)--
1,2-ethanediyltitanium dichloride, (methylamido)
(tetramethyl-.eta..sup.5--
cyclopentadienyl)-1,2-ethanediylzirconium dichloride,
(methylamido)(tetramethyl-.eta..sup.5-cyclopentadienyl)-1,2-ethanediyltit-
anium dichloride, (ethylamido)
(tetramethyl-.eta..sup.5-cyclopentadienyl)-- methylenetitanium
dichloro, (tert-butylamido)dibenzyl(tetramethyl-.eta..su-
p.5-cyclopentadienyl) silanezirconium dibenzyl,
(benzylamido)dimethyl-(tet-
ramethyl-.eta..sup.5-cyclopentadienyl)silanetitanium dichloride,
(phenylphosphido)dimethyl(tetramethyl-.eta..sup.5-cyclopentadienyl)silane-
zirconium dibenzyl, (tert-butylamido)dimethyl
(tetramethyl-.eta..sup.5-cyc- lopentadienyl)silanetitanium
dimethyl, and the like.
[0076] The complexes may be prepared by contacting a derivative of
a metal, M, and a group I metal derivative or Grignard derivative
of the cyclopentadienyl compound in a solvent and separating the
salt byproduct. Suitable solvents for use in preparing the metal
complexes are aliphatic or aromatic liquids such as cyclohexane
methylcyclohexane, pentane, hexane, heptane, tetrahydrofuran,
diethyl ether, benzene, toluene, xylene, ethylbenzene, etc., or
mixtures thereof.
[0077] In a preferred embodiment, the metal compound is MX.sub.n+i,
i.e. M is in a lower oxidation state than in the corresponding
compound, MX.sub.n+2 and the oxidation state of M in the desired
final complex. A noninterfering oxidizing agent may thereafter be
employed to raise the oxidation state of the metal. The oxidation
is accomplished merely by contacting the reactants utilizing
solvents and reaction conditions used in the preparation of the
complex itself. By the term "noninterfering oxidizing agent" is
meant a compound having an oxidation potential sufficient to raise
the metal oxidation state without interfering with the desired
complex formation or subsequent polymerization processes. A
particularly suitable noninterfering oxidizing agent is AgCl or an
organic halide such as methylene chloride. The foregoing techniques
are disclosed in U.S. Ser Nos.: 545,403, filed Jul. 3, 1990 and
702,475, filed May 20, 1991, the teachings of both of which are
incorporated herein by reference.
[0078] Additionally the complexes may be prepared according to the
teachings of the copending application entitled: "Preparation of
Metal Coordination Complex (I)", filed in the names of Peter
Nickias and David Wilson, on Oct. 15, 1991 and the copending
application entitled: "Preparation of Metal Coordination Complex
(II)", filed in the names of Peter Nickias and David Devore, on
Oct. 15, 1991, the teachings of which are incorporated herein by
reference thereto.
[0079] Suitable cocatalysts for use herein include polymeric or
oligomeric alumoxanes, especially methyl alumoxane, as well as
inert, compatible, noncoordinating, ion forming compounds.
Preferred cocatalysts are inert, noncoordinating, boron
compounds.
[0080] Ionic active catalyst species which can be used to
polymerize the polymers described herein correspond to the formula:
4
[0081] wherein:
[0082] M is a metal of group 3-10, or the Lanthanide series of the
Periodic Table of the Elements;
[0083] Cp* is a cyclopentadienyl or substituted cyclopentadienyl
group bound in an .eta..sup.5 bonding mode to M;
[0084] Z is a moiety comprising boron, or a member of group 14 of
the Periodic Table of the Elements, and optionally sulfur or
oxygen, said moiety having up to 20 non-hydrogen atoms, and
optionally Cp* and Z together form a fused ring system;
[0085] X independently each occurrence is an anionic ligand group
or neutral Lewis base ligand group having up to 30 non-hydrogen
atoms;
[0086] n is 0, 1, 2, 3, or 4 and is 2 less than the valence of M;
and
[0087] A.sup.- is a nonaccording, compatible anion.
[0088] One method of making the ionic catalyst species which can be
utilized to make the polymers of the present invention involve
combining:
[0089] a) at least one first component which is a
mono(cyclopentadienyl) derivative of a metal of Group 3-10 or the
Lanthanide Series of the Periodic Table of the Elements containing
at least one substituent which will combine with the cation of a
second component (described hereinafter) which first component is
capable of forming a cation formally having a coordination number
that is one less than its valence, and
[0090] b) at least one second component which is a salt of a
Bronsted acid and a noncoordinating, compatible anion.
[0091] More particularly the noncoordinating, compatible anion of
the Bronsted acid salt may comprise a single coordination complex
comprising a charge-bearing metal or metalloid core, which anion is
both bulky and non-nucleophilic. The recitation "metalloid", as
used herein, includes non-metals such as boron, phosphorus and the
like which exhibit semi-metallic characteristics.
[0092] Illustrative, but not limiting examples of
monocyclopentadienyl metal components (first components) which may
be used in the preparation of cationic complexes are derivatives of
titanium, zirconium, hafnium, chromium, lanthanum, etc. Preferred
components are titanium or zirconium compounds. Examples of
suitable monocyclopentadienyl metal compounds are
hydrocarbyl-substituted monocyclopentadienyl metal compounds such
as
(tert-butylamido)(tetramethyl-.eta..sup.5-cyclopentadienyl)-1,2-ethanediy-
lzirconium dimethyl,
(tert-butylamido)(tetramethyl-.eta..sup.5-cyclopentad-
ienyl)-1,2-ethanediyltitanium dimethyl,
(methylamido)(tetramethyl-.eta..su-
p.5-cyclopentadienyl)-i,2-ethanediylzirconium dibenzyl,
(methylamido)(tetramethyl-.eta..sup.5-cyclopentadienyl)-1,2-ethanediyltit-
anium dimethyl,
(ethylamido)(tetramethyl-.eta..sup.5-cyclopentadienyl)-met-
hylenetitanium dimethyl, (tert-butylamido)dibenzyl
(tetramethyl-.eta..sup.- 5-cyclopentadienyl) silanezirconium
dibenzyl, (benzylamido)dimethyl-(tetra-
methyl-.eta..sup.5-cyclopentadienyl)silanetitanium diphenyl,
(phenylphosphido)dimethyl(tetramethyl-.eta..sup.5-cyclopentadienyl)silane-
zirconium dibenzyl, and the like.
[0093] Such components are readily prepared by combining the
corresponding metal chloride with a dilithium salt of the
substituted cyclopentadienyl group such as a
cyclopentadienyl-alkanediyl, cyclopentadienyl-silane amide, or
cyclopentadienyl-phosphide compound. The reaction is conducted in
an inert liquid such as tetrahydrofuran. C.sub.5-10 alkanes,
toluene, etc utilizing conventional synthetic procedures.
Additionally, the first components may be prepared by reaction of a
group II derivative of the cyclopentadienyl compound in a solvent
and separating the salt by-product. Magnesium derivatives of the
cyclopentadienyl compounds are preferred. The reaction may be
conducted in an inert solvent such as cyclohexane, pentane,
tetrahydrofuran, diethyl ether benzene, toluene, or mixtures of the
like. The resulting metal cyclopentadienyl halide complexes may be
alkylated using a variety of techniques. Generally, the metal
cyclopentadienyl alkyl or aryl complexes may be prepared by
alkylation of the metal cyclopentadienyl halide complexes with
alkyl or aryl derivatives of group I or group II metals. Prererred
alkylating agents are alkyl lithium and Grignard derivatives using
conventional synthetic techniques. The reaction may be conducted in
an inert solvent such as cyclohexane, pentane, tetrahydrofuran,
diethyl ether, benzene, toluene, or mixtures of the like. A
preferred solvent is a mixture of toluene and tetrahydrofuran.
[0094] Compounds useful as a second component in the preparation of
the ionic catalysts useful in this invention will comprise a
cation, which is a Bronsted acid capable of donating a proton, and
a compatible noncoordinating anion. Preferred anions are those
containing a single coordination complex comprising a
charge-bearing metal or metalloid core which anion is relatively
large (bulky), capable of stabilizing the active catalyst species
(the Group 3-10 or Lanthanide Series cation) which is formed when
the two components are combined and sufficiently labile to be
displaced by olefinic, diolefinic and acetylenically unsaturated
substrates or other neutral Lewis bases such as ethers, nitriles
and the like. Suitable metals, then, include, but are not limited
to, aluminum, gold, platinum and the like. Suitable metalloids
include, but are not limited to, boron, phosphorus, silicon and the
like. Compounds containing anions which comprise coordination
complexes containing a single metal or metalloid atom are, of
course, well known and many, particularly such compounds containing
a single boron atom in the anion portion, are available
commercially. In light of this, salts containing anions comprising
a coordination complex containing a single boron atom are
preferred.
[0095] Highly preferably, the second component useful in the
preparation of the catalysts of this invention may be represented
by the following general formula:
(L--H).sup.+[A]
[0096] wherein:
[0097] L is a neutral Lewis base;
[0098] (L--H).sup.+ is a Bronsted acid; and
[0099] [A].sup.- is a compatible, noncoordinating anion.
[0100] More preferably [A].sup.- corresponds to the formula:
[M'Q.sub.q].sup.-
[0101] wherein:
[0102] M' is a metal or metalloid selected from Groups 5-15 of the
Periodic Table of the Elements; and
[0103] Q independently each occurrence is selected from the Group
consisting of hydride, dialkylamido, halide, alkoxide, aryloxide,
hydrocarbyl, and substituted-hydrocarbyl radicals of up to 20
carbons with the proviso that in not more than one occurrence is Q
halide and
[0104] q is one more than the valence of M'.
[0105] Second components comprising boron which are particularly
useful in the preparation of catalysts of this invention may be
represented by the following general formula:
[L--H].sup.+[BQ.sub.4]
[0106] wherein:
[0107] L is a neutral Lewis base;
[0108] [L--H].sup.+ is a Bronsted acid;
[0109] B is boron in a valence state of 3; and
[0110] Q is as previously defined.
[0111] Illustrative, but not limiting, examples of boron compounds
which may be used as a second component in the preparation of the
improved catalysts of this invention are trialkyl-substituted
ammonium salts such as triethylammonium tetraphenylborate,
tripropylammonium tetraphenylborate, tri(n-butyl)ammonium
tetraphenylborate, trimethylammonium tetra(p-tolylborate),
tributylammonium tetrakis-pentafluorophenylborate,
tripropylammonium tetrakis-2,4-dimethylphenylborate,
tributylammonium tetrakis-3,5-dimethylphenylborate,
triethylammonium tetrakis-(3,5-di-trifluoromethylphenyl)borate and
the like. Also suitable are N,N-dialkyl anilinium salts such as
N,N-dimethylanilinium tetraphenylborate, N,N-diethylanilinium
tetraphenylborate, N,N-2,4,6-pentaniethylanilinium
tetraphenylborate and the like; dialkyl ammonium salts such as
di-(i-propyl)ammonium tetrakis-pentafluorophenylbo- rate,
dicyclohexylammonium tetraphenylborate and the like; and triaryl
phosphonium salts such as triphenylphosphonium tetraphenylborate,
tri(methylphenyl)phosphonium tetrakis-pentafluorophenylborate,
tri(dimethylphenyl)phosphonium tetraphenylborate and the like.
[0112] Preferred ionic catalysts are those having a limiting charge
separated structure corresponding to the formula: 5
[0113] wherein:
[0114] M is a metal of group 3-10, or the Lanthanide series of the
Periodic Table of the Elements;
[0115] Cp* is a cyclopentadienyl or substituted cyclopentadienyl
group bound in an .eta..sup.5 bonding mode to M;
[0116] Z is a moiety comprising boron, or a member of group 14 of
the Periodic Table of the Elements, and optionally sulfur or
oxygen, said moiety having up to 20 non-hydrogen atoms, and
optionally Cp* and Z together form a fused ring system;
[0117] X independently each occurrence is an anionic ligand group
or neutral Lewis base ligand group having up to 30 non-hydrogen
atoms;
[0118] n is 0, 1, 2, 3, or 4 and is 2 less than the valence of M;
and
[0119] XA*.sup.- is .sup.-XB(C.sub.6F.sub.5).sub.3.
[0120] This class of cationic complexes may be conveniently
prepared by contacting a metal compound corresponding to the
formula: 6
[0121] wherein:
[0122] Cp, M, and n are as previously defined,
[0123] with tris(pentafluorophenyl)borane cocatalyst under
conditions to cause abstraction of X and formation of the anion
.sup.-XB(C.sub.6F.sub.5- ).sub.3.
[0124] Preferably X in the foregoing ionic catalyst is
C.sub.1-C.sub.10 hydrocarbyl, most preferably methyl.
[0125] The preceding formula is referred to as the limiting, charge
separated structure. However, it is to be understood that,
particularly in solid form, the catalyst may not be fully charge
separated. That is, the X group may retain a partial covalent bond
to the metal atom, M. Thus, the catalysts may be alternately
depicted as possessing the formula: 7
[0126] The catalysts are preferably prepared by contacting the
derivative of a Group 4 or Lanthanide metal with the
tris(pentafluorophenyl)borane in an inert diluent such as an
organic liquid. Tris(pentafluorphenyl)bora- ne is a commonly
available Lewis acid that may be readily prepared according to
known techniques. The compound is disclosed in Marks, et al J. Am.
Chem. Soc. 1991, 113, 3623-3625 for use in alkyl abstraction of
zirconocenes.
[0127] All reference to the Periodic Table of the Elements herein
shall refer to the Periodic Table of the Elements, published and
copyrighted by CRC Press, Inc., 1989. Also, any reference to a
Group or Groups shall be to the Group or Groups as reflected in
this Periodic Table of the Elements using the IUPAC system for
numbering groups.
[0128] It is believed that in the contstrained geometry catalysts
used herein the metal atom is forced to greater exposure of the
active metal site because one or more substituents on the single
cyclopentadienyl or substituted cyctopentadienyl group forms a
portion of a ring structure including the metal atom, wherein the
metal is both bonded to an adjacent covalent moiety and held in
association with the cyclopentadienyl group through an .eta..sup.5
or other n-bonding interaction. It is understood that each
respective bond between the metal atom and the constituent atoms of
the cyclopentadienyl or substituted cyclopentadienyl group need not
be equivalent. That is, the metal may be symmetrically or
unsymmetrically n-bound to the cyclopentadienyl or substituted
cyclopentadienyl group.
[0129] The geometry of the active metal site is further defined as
follows. The centroid of the cyclopentadienyl or substituted
cyclopentadienyl group may be defined as the average of the
respective X, Y, and Z coordinates of the atomic centers forming
the cyclopentadienyl or substituted cyclopentadienyl group. The
angle, .theta., formed at the metal center between the centroid of
the cyclopentadienyl or substituted cyclopentadienyl group and each
other ligand of the metal complex may be easily calculated by
standard techniques of single crystal X-ray diffraction. Each of
these angles may increase or decrease depending on the molecular
structure of the constrained geometry metal complex. Those
complexes wherein one or more of the angles, .theta., it less than
in a similar, comparative complex differing only in the fact that
the constrain-inducing substituent is replaced by hydrogen have
constrained geometry for purposes of the present invention.
Preferably one or more of the above angles, .theta., decrease by at
least 5 percent, more preferably 7.5 percent, compared to the
comparative complex. Highly preferably, the average value of all
bond angles, .theta., is also less than in the comparative
complex.
[0130] Preferably, monocyclopentadienyl metal coordination
complexes of group 4 or lanthanide metals according to the present
invention have constrained geometry such that the smallest angle,
.theta., is less than 115.degree., more preferably less than
110.degree., most preferably less than 105.degree..
[0131] Other compounds which are useful in the catalyst
compositions of this invention, especially compounds containing
other Group 4 or Lanthanide metals, will, of course be apparent to
those skilled in the art.
[0132] In general, the polymerization according to the present
invention may be accomplished at conditions well known in the prior
art for Ziegler-Natta or Kaminsky-Sinn type polymerization
reactions, that is, temperatures from 0 to 250.degree. C. and
pressures from atmospheric to 1000 atmospheres (100 MPa).
Suspension, solution, slurry, gas phase or other process conditions
may be employed if desired. A support may be employed but
preferably the catalysts are used in a homogeneous manner. It will,
of course, be appreciated that the active catalyst system,
especially nonionic catalysts, form in situ if the catalyst and the
cocatalyst components thereof are added directly to the
polymerization process and a suitable solvent or diluent, including
condensed monomer, is used in said polymerization process. It is,
however, preferred to form the active catalyst in a separate step
in a suitable solvent prior to adding the same to the
polymerization mixture.
[0133] The polymerization conditions for manufacturing the polymers
of the present invention are generally those useful in the solution
polymerization process, although the application of the present
invention is not limited thereto. Gas phase polymerization
processes are also believed to be useful, provided the proper
catalysts and polymerization conditions are employed.
[0134] Fabricated articles made from the novel olefin polymers may
be prepared using all of the conventional polyolefin processing
techniques. Useful articles include films (e.g., cast, blown and
extrusion coated), fibers (e.g., staple fibers (including use of a
novel olefin polymer disclosed herein as at least one component
comprising at least a portion of the fiber's surface), spunbond
fibers or melt blown fibers (using, e.g., systems as disclosed in
U.S. Pat. No. 4,340,563, U.S. Pat. No. 4,663,220, U.S. Pat. No.
4,668,566, or U.S. Pat. No. 4,322,027, all of which are
incorporated herein by reference), and gel spun fibers (e.g., the
system disclosed in U.S. Pat. No. 4,413,110, incorporated herein by
reference)), both woven and nonwoven fabrics (e.g., spunlaced
fabrics disclosed in U.S. Pat. No. 3,485,706, incorporated herein
by reference) or structures made from such fibers (including, e.g.,
blends of these fibers with other fibers, e.g., PET or cotton) and
molded articles (e.g., made using an injection molding process, a
blow molding process or a rotomolding process). The new polymers
described herein are also useful for wire and cable coating
operations, as well as in sheet extrusion for vacuum forming
operations.
[0135] Useful compositions are also suitably prepared comprising
the substantially linear polymers of the present invention and at
least one other natural or synthetic polymer. Preferred other
polymers include thermoplastics such as styrene-butadiene block
copolymers, polystyrene (including high impact polystyrene),
ethylene vinyl alcohol copolymers, ethylene acrylic acid
copolymers, other olefin copolymers (especially polyethylene
copolymers) and homopolymers (e.g., those made using conventional
heterogeneous catalysts). Examples include polymers made by the
process of U.S. Pat. No. 4,076,698, incorporated herein by
reference, other linear or substantially linear polymers of the
present invention, and mixtures thereof. Other substantially linear
polymers of the present invention and conventional HDPE and/or
LLDPE are preferred for use in the thermoplastic compositions.
[0136] Compositions comprising the olefin polymers can also be
formed into fabricated articles such as those previously mentioned
using conventional polyolefin processing techniques which are well
known to those skilled in the art of polyolefin processing.
[0137] All procedures were performed under an inert atmosphere or
nitrogen or argon. Solvent choices were often optional, for
example, in most cases either pentane or 30-60 petroleum ether can
be interchanged. Amines, silanes, lithium reagents, and Grignard
reagents were purchased from Aldrich Chemical Company. Published
methods for preparing tetramethylcyclopentadiene
(C.sub.5Me.sub.4H.sub.2) and lithium tetramethylcyclopentadienide
(Li(C.sub.5Me.sub.4H)) include C. M. Fendrick et al.
Organometallics, 3, 819 (1984). Lithiated substituted
cyclopentadienyl compounds may be typically prepared from the
corresponding cyclopentadiene and a lithium reagent such as n-butyl
lithium. Titanium trichloride (TiCl.sub.3) was purchased from
Aldrich Chemical Company. The tetrahydrofuran adduct of titanium
trichloride, TiCl.sub.3(THF).sub.3, was prepared by refluxing
TiCl.sub.3 in THF overnight, cooling, and isolating the blue solid
product, according to the procedure of L. E. Manzer, Inorg. Syn.,
21, 135 (1982).
EXAMPLES 1-4
[0138] The metal complex solution for Example 1 is prepared as
follows:
[0139] Part 1: Prep of Li(C.sub.5Me.sub.4H)
[0140] In the drybox, a 3L 3-necked flask was charged with 18.34 g
of C.sub.5Me.sub.4H.sub.2, 800 mL of pentane, and 500 mL of ether.
The flask was topped with a reflux condenser, a mechanical stirrer,
and a constant addition funnel container 63 mL of 2.5 M n-Buli in
hexane. The BuLi was added dropwise over several hours. A very
thick precipitate formed: approve 1000 mL of additional pentane had
to be added over the course of the reaction to allow stirring to
continue. After the addition was complete, the mixture was stirred
overnight. The next day, the material was filtered, and the solid
was thoroughly washed with pentane and then dried under reduced
pressure. 14.89 g of Li(C.sub.5Me.sub.4H) was obtained (78
percent).
[0141] Part 2: Prep of C.sub.5Me.sub.4HSMe.sub.2Cl
[0142] In the drybox 30.0 g of Li(C.sub.5Me.sub.4H) was placed in a
500 mL Schlenk flask with 250 mL of THF and a large magnetic stir
bar. A syringe was charged with 30 mL of Me.sub.2SiCl.sub.2 and the
flask and syringe were removed from the drybox. On the Schlenk line
under a flow of argon, the flask was cooled to -78.degree. C., and
the Me.sub.2SiCl.sub.2 added in one rapid addition. The reaction
was allowed to slowly warm to room temperature and stirred
overnight. The next morning the volatile materials were removed
under reduced pressure, and the flask was taken into the drybox.
The oily material was extracted with pentane, filtered, and the
pentane was removed under reduced pressure to leave the
C.sub.5Me.sub.4HSiMe.sub.2Cl as a clear yellow liquid (46.83 g;
92.9 percent).
[0143] Part 3: Prep of C.sub.5Me.sub.4HSiMe.sub.2NH.sup.tBu
[0144] In the drybox, a 3-necked 2 L flask was charged with 37.4 g
of t-butylamine and 210 mL of THF. C.sub.5Me.sub.4HSiMe.sub.2Cl
(25.47 g) was slowly dripped into the solution over 3-4 hours. The
solution turned cloudy and yellow. The mixture was stirred
overnight and the volatile materials removed under reduced
pressure. The residue was extracted with diethyl ether, the
solution was filtered, and the ether removed under reduced pressure
to leave the C.sub.5Me.sub.4HSiMe.sub.2NH.sup.tBu as a clear yellow
liquid (26.96 g; 90.8 percent).
[0145] Part 4: Prep of
[MgCl].sub.2[Me.sub.4C.sub.5SiMe.sub.2N.sup.tBu](TH- F).sub.x
[0146] In the drybox, 14.0 mL of 2.0 M isopropylmagnesium chloride
in ether was syringed into a 250 mL flask. The ether was removed
under reduced pressure to leave a colorless oil. 50 mL of a 4:1 (by
volume) toluene:THF mixture was added followed by 3.50 g of
Me.sub.4HC.sub.5SiMe.sub.2NH.sup.tBu. The solution was heated to
reflux. After refluxing for 2 days, the solution was cooled and the
volatile materials removed under reduced pressure. The white solid
residue was slurried in pentane and filtered to leave a white
powder, which was washed with pentane and dried under reduced
pressure. The white powder was identified as
[MgCl].sub.2[Me.sub.4C.sub.5SiMe.sub.2N Bu](THF).sub.x (yield: 6.7
g).
[0147] Part 5: Prep of
[C.sub.5Me.sub.4(SiMe.sub.2N.sup.tBu)]TiCl.sub.2
[0148] In the drybox, 0.50 g of TiCl.sub.3(THF).sub.3 was suspended
in 10 mL of THF 0.69 g of solid
[MgCl].sub.2[Me.sub.4C.sub.5SiMe.sub.2N.sup.tBu- ](THF).sub.x was
added, resulting in a color change from pale blue to deep purple.
After 15 minutes, 0.35 g of AgCl was added to the solution. The
color immediately began to lighten to a pale green-yellow. After
11/2 hours, the THF was removed under reduced pressure to leave a
yellow-green solid. Toluene (20 mL) was added, the solution was
filtered, and the toluene was removed under reduced pressure to
leave a yellow-green solid, 0.51 g (quantitative yield) identified
by 1H NMR as [C.sub.5Me.sub.4(SiMe.sub.2N.sup.tBu)]TiCl.sub.2.
[0149] Part 6: Preparation of
[C.sub.5Me.sub.4(SiMe.sub.2N.sup.tBu)]TiMe.s- ub.2
[0150] In an inert atmosphere glove box, 9.031 g of
[C.sub.5Me.sub.4(Me.sub.2SiN.sup.tBu)]TiCl.sub.2 is charged into a
250 ml flask and dissolved into 100 ml of THF. This solution is
cooled to about -25.degree. C. by placement in the glove box
freezer for 15 minutes. To the cooled solution is added 35 ml of a
1.4 M MeMgBr solution in toluene/THF (75/25). The reaction mixture
is stirred for 20 to 25 minutes followed by removal of the solvent
under vacuum. The resulting solid is dried under vacuum for several
hours. The product is extracted with pentane (4.times.50 ml) and
filtered. The filtrate is combined and the pentane removed under
vacuum giving the catalyst as a straw yellow solid.
[0151] The metal complex,
[C.sub.5Me.sub.4(SiMe.sub.2N.sup.tBu)]TiMe.sub.2- , solution for
Examples 2 and 3 is prepared as follows:
[0152] In an inert atmosphere glove box 10.6769 g of a
tetrahydrofuran adduct of titanium trichloride,
TiCl.sub.3(THF).sub.3, is loaded into a 1 l flask and slurried into
.apprxeq.300 ml of THF. To this slurry, at room temperature, is
added 17.402 g of [MgCl].sub.2 [N.sup.tBuSiMe.sub.2C.sub.-
5Me.sub.9] (THF).sub.x as a solid. An additional 200 ml of THF is
used to help wash this solid into the reaction flask. This addition
resulted in an immediate reaction giving a deep purple solution.
After stirring for 5 minutes 9.23 ml of a 1.56 M solution of
CH.sub.2Cl.sub.2 in THF is added giving a quick color change to
dark yellow. This stage of the reaction is allowed to stir for
about 20 to 30 minutes. Next, 61.8 ml of a 1.4 M MeMgBr solution in
toluene/THF(75/25) is added via syringe. After about 20 to 30
minutes stirring time the solvent is removed under vacuum and the
solid dried. The product is extracted with pentane (8.times.50 ml)
and filtered. The filtrate is combined and the pentane removed
under vacuum giving the metal complex as a tan solid.
[0153] The metal complex, [C.sub.5
Me.sub.4(SiMe.sub.2N.sup.tBu))TiMe.sub.- 2, solution for Example 4
is prepared as follows:
[0154] In an inert atmosphere glove box 4.8108 g of
TiCl.sub.3(thf).sub.3 is placed in a 500 ml flask and slurried into
130 ml of THF In a separate flask 8.000 g of
[MgCl].sub.2N.sup.tBuSiMe.sub.2C.sub.5Me.sub.4](THF).sub- .x is
dissolved into 150 ml of THF. These flasks are removed from the
glove box and attached to a vacuum line and the contents cooled to
-30.degree. C. The THF solution of
[MgCl].sub.2[N.sup.tBuSiMe.sub.2C.sub.- 5Me.sub.4](THF).sub.x is
transferred (over a 15 minute period) via cannula to the flask
containing the TiCl.sub.3(THF).sub.3 slurry. This reaction is
allowed to stir for 1.5 hours over which time the temperature
warmed to 0.degree. C. and the solution color turned deep purple.
The reaction mixture is cooled back to -30.degree. C. and 4.16 ml
of a 1.56 M CH.sub.2Cl.sub.2 solution in THF is added. This stage
of the reaction is stirred for an additional 1.5 hours and the
temperature warmed to -10.degree. C. Next, the reaction mixture is
again cooled to -40.degree. C. and 27.81 ml of a 1.4 M MeMgBr
solution in toluene/THF (75/25) was added via syringe and the
reaction is now allowed to warm slowly to room temperature over 3
hours. After this time the solvent is removed under vacuum and the
solid dried. At this point the reaction flask is brought back into
the glove box where the product is extracted with pentane
(4.times.50 ml) and filtered. The filtrate is combined and the
pentane removed under vacuum giving the catalyst as a tan solid.
The metal complex is then dissolved into a mixture of
C.sub.8-C.sub.10 saturated hydrocarbons (e.g., Isopar E, made by
Exxon) and ready for use in polymerization.
[0155] Polymerization
[0156] The polymer products of Examples 1-4 are produced in a
solution polymerization process using a continuously stirred
reactor. Additives (e.g., antioxidants, pigments, etc.) can be
incorporated into the interpolymer products either during the
pelletization step or after manufacture, with a subsequent
re-extrusion. Examples 1-4 are each stabilized with 1250 ppm
Calcium Stearate, 200 ppm Irgonox 1010, and 1600 ppm Irgafos 168.
Irgafos.TM. 168 is a phosphite stabilizer and Irgonox.TM. 1010 is a
hindered polyphenol stabilizer (e.g., tetrakis [methylene
3-(3,5-ditert.butyl-4-hydroxy-phenylpropionate)]methane. Both are
trademarks of and made by Ciba-Geigy Corporation. A representative
schematic for the polymerization process is shown in FIG. 1.
[0157] The ethylene (4) and the hydrogen are combined into on
stream (15) before being introduced into the diluent mixture (3).
Typically, the diluent mixture comprises a mixture of
C.sub.8-C.sub.10 saturated hydrocarbons (1), (e.g., Isopar.RTM. E,
made by Exxon) and the comonomer(s) (2). For examples 1-4, the
comonomer is 1-octene. The reactor feed mixture (6) is continuously
injected into the reactor (9). The metal complex (7) and the
cocatalyst (8) (the cocatalyst is tris(pentafluorophenyl)borane for
Examples 1-4 herein which forms the ionic catalyst insitu) are
combined into a single stream and also continuously injected into
the reactor. Sufficient residence time is allowed for the metal
complex and cocatalyst to react to the desired extent for use in
the polymerization reactions, at least about 10 seconds. For the
polymerization reactions of Examples 1-4, the reactor pressure is
held constant at about 490 psig. Ethylene content of the reactor,
after reaching steady state, is maintained below about 8
percent.
[0158] After polymerization, the reactor exit stream (14) is
introduced into a separator (10) where the molten polymer is
separated from the unreacted comonomer(s), unreacted ethylene,
unreacted hydrogen, and diluent mixture stream (13). The molten
polymer is subsequently strand chopped or pelletized and, after
being cooled in a water bath or pelletizer (11), the solid pellets
are collected (12). Table I describes the polymerization conditions
and the resultant polymer properties:
1 TABLE I Example 1 2 3 4 Ethylene feed 3.2 3.8 3.8 3.8 rate
(lbs/hour) Comonomer/ 12.3 0 0 0 Olefin* ratio (mole %) Hydrogen/
0.054 0.072 0.083 0.019 Ethylene ratio (mole %) Diluent/ 9.5 7.4
8.7 8.7 Ethylene ratio (weight basis) metal 0.00025 0.0005 0.001
0.001 complex concentration (molar) metal 5.9 1.7 2.4 4.8 complex
flow rate (ml/min) cocatalyst 0.001 0.001 0.002 0.002 concentration
(molar) cocatalyst 2.9 1.3 6 11.9 flow rate (ml/min) Reactor 114
160 160 200 temperature (.degree. C.) Ethylene 2.65 3.59 0.86 1.98
Conc. in the reactor exit stream (weight percent) Product I.sub.2
1.22 0.96 1.18 0.25 (g/10 minutes) Product 0.903 0.954 0.954 0.953
density (g/cc) Product I.sub.10/I.sub.2 6.5 7.4 11.8 16.1 Product
1.86 1.95 2.09 2.07 M.sub.w/M.sub.n *For Examples 1-4, the
Comonomer/Olefin ratio is defined as the percentage molar ratio of
((1-octene/(1-octene + ethylene))
[0159] The .sup.13C NMR spectrum of Example 3 (ethylene
homopolymer) shows peaks which can be assigned to the
.alpha..delta.+, .beta..delta.+, and methine carbons associated
with a long chain branch. Long chain branching is determined using
the method of Randall described earlier in this disclosure, wherein
he states that "Detection of these resonances in high-density
polyethylenes where no 1-olefins were added during the
polymerization should be strongly indicative of the presence of
long chain branching." Using the equation 141 from Randall (p.
292).
Branches per 10,000
carbons=[1/3.alpha./T.sub.Tot)].times.10.sup.4,
[0160] wherein .alpha.=the average intensity of a carbon from a
branch (.alpha..delta.+) carbon and T.sub.Tot=the total carbon
intensity,
[0161] the number of long chain branches in this sample is
determined to be 3.4 per 10,000 carbon atoms, or 0.34 long chain
branches/1000 carbon atoms.
EXAMPLE 5, 6 AND COMPARATIVE EXAMPLES 7-9
[0162] Examples 5, 6 and comparison examples 7-9 with the same melt
index are tested for rheology comparison. Examples 5 and 6 are the
substantially linear polyethylenes produced by the constrained
geometry catalyst technology, as described in Examples 1-4.
Examples 5 and 6 are stablized as Examples 1-4.
[0163] Comparison examples 7, 8 and 9 are conventional
heterogeneous Ziegler polymerization blown film resins Dowlex.RTM.
2045A, Attane.RTM. 4201, and Attane.RTM. 4403, respectively, all of
which are ethylene/1-octene copolymers made by The Dow Chemical
Company. Comparative example 7 is stablized with 200 ppm
Irgonox.RTM. 1010, and 1600 ppm Irgafos.RTM. 168 while comparative
examples 8 and 9 are stablized with 200 ppm Irgonox.RTM. 1010 and
800 ppm PEPQ.RTM.. PEPQ.RTM. is a trademark of Sandoz Chemical, the
primary ingredient of which is believed to be
tetrakis-(2,4-di-tertbutyl-phenyl)-4,4' biphenylphosphonite.
[0164] A comparison of the physical properties of each example and
comparative example is listed in Table II.
2TABLE II Com- Com- parison parison Comparison Property Example 5
Example 6 Example 7 Example 8 Example 9 I.sub.2 1 1 1 1 0.76
density .92 .902 .92 .912 .905 I.sub.10/I.sub.2 9.45 7.61 7.8-8 8.2
8.7 M.sub.w/M.sub.n 1.97 2.09 3.5-3.8 3.8 3.8-4.0
[0165] Surprisingly, even though the molecular weight distribution
of Examples 5 and 6 is narrow (i.e., M.sub.w/M.sub.n is low), the
I.sub.10/I.sub.2 values are higher in comparison with comparative
examples 7-9. A comparison of the relationship between
I.sub.10/I.sub.2 vs M.sub.w/M.sub.n for some of the novel polymers
described herein and conventional heterogeneous Ziegler polymers is
given in FIG. 2. The I.sub.10/I.sub.2 value for the novel polymers
of the present invention is essentially independent of the
molecular weight distribution, M.sub.w/M.sub.n, which is not true
for conventional Ziegler polyerized resins.
[0166] Example 5 and comparison example 7 with similar melt index
and density (Table II) are also extruded via a Gas Extrusion
Rheometer (GER) at 190.degree. C. using a 0.0296" diameter, 20 L/D
die. The processing index (P.I.) is measured at an apparent shear
stress of 2.15.times.10.sup.6 dyne/cm.sup.2 as described
previously. The onset of gross melt fracture can easily be
identified from the shear stress vs shear rate plot shown in FIG. 3
where a sudden jump of shear rate occurs. A comparison of the shear
stresses and corresponding shear rates before the onset of gross
melt fracture is listed in Table III. It is particularly
interesting that the PI or Example 5 is more than 20% lower than
the PI of comparative example 7 and that the onset of melt fracture
or sharkskin for Example 5 is also at a significantly higher shear
stress and shear rate in comparison with the comparative example 7.
Furthermore, the Melt Tension (MT) as well as Elastic Modulus of
Example 5 are higher than that of comparative example 7.
3 TABLE III Comparison Property Example 5 example 7 I.sub.2 1 1
I.sub.10/I.sub.2 9.45 7.8-8 PI, kpoise 11 15 Melt Tension 1.89 1.21
Elastic Modulus 2425 882.6 @.1 rad/sec (dyne/cm.sup.2) OGMF*,
critical >1556 (not 936 shear rate (1/sec) observed) OGMF*,
critical .452 .366 shear stress (MPa) OSMF**, critical >1566
(not .about.628 shear rate (1/sec) observed) OSMF**, critical
.about.0.452 .about.0.25 shear stress (MPa) *Onset of Gross Melt
Fracture. **Onset of Surface Melt Fracture.
[0167] Example 6 and comparison example 9 have similar melt index
and density, but example 6 has lower I.sub.10/I.sub.2 (Table IV).
These polymers are extruded via a Gas Extrusion Rheometer (GER) at
190.degree. C. using a 0.0296 inch diameter, 20:1 L/D die. The
processing index (PI) is measured at an apparent shear stress of
2.15.times.10.sup.6 dyne/cm.sup.2 as described previously.
4 TABLE IV Comparison Property Example 6 example 9 I.sub.2 (g/10
minutes) 1 0.76 I.sub.10/I.sub.2 7.61 8.7 PI (kpoise) 14 15 Melt
Tension (g) 1.46 1.39 Elastic Modulus 1481 1921 @ 0.1 rad/sec
(dyne/cm2) OGMF*, critical 1186 652 shear rate (1/sec) OGMF*,
critical 0.431 0.323 shear stress (MPa) OSMF**, critical .about.764
.about.402 shear rate (1/sec) OSMF**, critical 0.366 0.280 shear
stress (MPa) *Onset of Gross Melt Fracture. **Onset of Surface Melt
Fracture.
[0168] The onset of gross melt fracture can easily be identified
from the shear stress vs. shear rate plot shown in FIG. 4 where a
sudden increase of shear rate occurs at an apparent shear stress of
about 3.23.times.10.sup.6 dyne/cm.sup.2 (0.323 MPa). A comparison
of the shear stresses and corresponding shear rates before the
onset of gross melt fracture is listed in Table IV. The PI of
Example 6 is surprisingly about the same as comparative example 9,
even though the I.sub.10/I.sub.2 is lower for Example 6. The onset
of melt fracture or sharkskin for Example 6 is also at a
significantly higher shear stress and shear rate in comparison with
the comparative example 9. Furthermore, it is also unexpected that
the Melt Tension (MT) of Example 6 is higher than that of
comparative example 9, even though the melt index for Example 6 is
slightly higher and the I.sub.10/I.sub.2 is slightly lower than
that of comparative example 9.
EXAMPLE 10 AND COMPARATIVE EXAMPLE 11
[0169] Blown film is fabricated from two novel ethylene/1-octene
polymers made in accordance with the present invention and from two
comparative conventional polymers made according to conventional
Ziegler catalysis. The blown films are tested for physical
properties, including heat seal strength versus heat seal
temperature (shown in FIG. 5 for Examples 10 and 12 and comparative
examples 11 and 13) machine (MD) and cross direction (CD)
properties (e.g., tensile yield and break, elongation at break and
Young's modulus). Other film properties such as dart, puncture,
tear, clarity, haze, 20 degree gloss and block are also tested.
[0170] Blown Film Fabrication Conditions
[0171] The improved processing substantially linear polymers of the
present invention produced via the procedure described earlier, as
well as two comparative resins are fabricated on an Egan blown film
line using the following fabrication conditions:
[0172] 2 inch extruder
[0173] 3 inch die
[0174] 30 mil die gap
[0175] 25 RPM extruder speed
[0176] 460.degree. F. melt temperature
[0177] 1 mil gauge
[0178] 2.7:1 Blow up ratio (12.5 inches layflat)
[0179] 12.5 inches frost line height
[0180] The melt temperature is kept constant by changing the
extruder temperature profile. Frost line height is maintained at
12.5 inches by adjusting the air flow. The extruder output rate,
back pressure and power consumption in amps are monitored
throughout the experiment. The polymers of the present invention
and the comparative polymers are all ethylene/1-octene copolymers.
Table VI summarizes physical properties of the two polymers of the
invention and for the two comparative polymers:
5TABLE VI Comparative Comparative Property Example 10 example 11
Example 12 example 13 I.sub.2 1 1 1 0.8 (g/10 minutes) Density 0.92
0.92 0.902 0.905 (g/cc) I.sub.10/I.sub.2 9.45 .about.8 7.61 8.7
M.sub.w/M.sub.n 2 .about.5 2 .about.5
[0181] Tables VII and VIII summarize the film properties measured
for blown film made from two of these four polymers:
6TABLE VII Blown film properties Comparative Example 10 example 11
Property MD CD MD CD Tensile yield 1391 1340 1509 1593 (psi)
Tensile break 7194 5861 6698 6854 (psi) elongation 650 668 631 723
(percent) Young's 18990 19997 23086 23524 Modulus (psi) PPT* Tear
5.9 6.8 6.4 6.5 (gm) *Puncture Propagation Tear
[0182]
7 TABLE VIII Comparative Property Example 10 example 11 Dart A (gm)
472 454 Puncture 235 275 (grams) clarity 71 68 (percent) Haze 3.1
6.4 20.degree. gloss 114 81 Block 148 134 (grams)
[0183] During the blown film fabrication, it is noticed that at the
same screw speed (25 rpm) and at the same temperature profile, the
extruder back pressure is about 3500 psi at about 58 amps power
consumption for comparative example 11 and about 2550 psi at about
48 amps power consumption for example 10, thus showing the novel
polymer of example 10 to have improved processability over that of
a conventional heterogeneous Ziegler polymerized polymer. The
throughput is also higher for Example 10 than for comparative
example 11 at the same screw speed. Thus, example 10 has higher
outputting efficiency than comparative example 11 (i.e., more
polymer goes through per turn of the screw).
[0184] As FIG. 5 shows, the heat seal properties of polymers of the
present invention are improved, as evidenced by lower heat seal
initiation temperatures and higher heat seal strengths at a given
temperature, as compared with conventional heterogeneous polymers
at about the same melt index and density.
* * * * *