U.S. patent application number 10/314367 was filed with the patent office on 2003-07-24 for homopolymers and copolymers of ethylene.
This patent application is currently assigned to BP Chemicals Limited. Invention is credited to Chai, Choon Kooi.
Application Number | 20030139551 10/314367 |
Document ID | / |
Family ID | 10824911 |
Filed Date | 2003-07-24 |
United States Patent
Application |
20030139551 |
Kind Code |
A1 |
Chai, Choon Kooi |
July 24, 2003 |
Homopolymers and copolymers of ethylene
Abstract
Ethylene homopolymers and copolymers having a broad molecular
distribution, excellent toughness and improved processability are
disclosed. These polymers may be prepared by use of a single
metallocene catalyst system in a single reactor in the gas phase.
These polymers of density typically 0.85-40.95 are defined in
particular by their melt strength (MS) and long chain branching
(LCB) characteristics and are particularly suitable for use in low
density film applications.
Inventors: |
Chai, Choon Kooi; (Cabries,
FR) |
Correspondence
Address: |
FINNEGAN, HENDERSON, FARABOW, GARRETT &
DUNNER LLP
1300 I STREET, NW
WASHINGTON
DC
20006
US
|
Assignee: |
BP Chemicals Limited
|
Family ID: |
10824911 |
Appl. No.: |
10/314367 |
Filed: |
December 9, 2002 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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10314367 |
Dec 9, 2002 |
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09600107 |
Jul 6, 2000 |
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6518385 |
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09600107 |
Jul 6, 2000 |
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PCT/GB99/00021 |
Jan 5, 1999 |
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Current U.S.
Class: |
526/266 ;
526/287; 526/318.44; 526/319 |
Current CPC
Class: |
C08F 4/65927 20130101;
C08F 4/65916 20130101; C08F 10/02 20130101; C08J 5/18 20130101;
C08F 10/00 20130101; C08J 2323/04 20130101; C08F 110/02 20130101;
C08F 210/16 20130101; C08F 4/65908 20130101; C08F 10/00 20130101;
C08F 4/65916 20130101; C08F 210/16 20130101; C08F 4/65927 20130101;
C08F 110/02 20130101; C08F 2500/12 20130101; C08F 2500/20 20130101;
C08F 2500/11 20130101; C08F 2500/26 20130101; C08F 2500/09
20130101; C08F 110/02 20130101; C08F 2500/12 20130101; C08F 2500/09
20130101; C08F 2500/20 20130101; C08F 2500/11 20130101; C08F
2500/26 20130101; C08F 210/16 20130101; C08F 210/14 20130101; C08F
2500/12 20130101; C08F 2500/09 20130101; C08F 2500/20 20130101;
C08F 2500/11 20130101; C08F 2500/26 20130101 |
Class at
Publication: |
526/266 ;
526/287; 526/318.44; 526/319 |
International
Class: |
C08F 134/02 |
Foreign Application Data
Date |
Code |
Application Number |
Jan 7, 1998 |
GB |
9800245.4 |
Claims
claims:
1. A copolymer of ethylene and one or more alpha olefins containing
from three to twenty carbon atoms said copolymer having: a) a long
chain branching g' value of less than or equal to 0.9 and b) a
value of the derivative function .delta.(MS)/.delta.(P) of greater
than 0.6 wherein MS is the melt strength of the copolymer in cN and
P is the extrusion pressure of the copolymer in MPa.
2. A copolymer as claimed in claim 1 wherein g' is less than or
equal to 0.8.
3. A copolymer as claimed in claim 1 wherein g' is in the range 0.5
to 0-9.
4. A copolymer as claimed in claim 3 wherein g' is in the range
0.55 to 0.85.
5. A copolymer as claimed in claim 4. wherein g' is in the range
0.65 to 0.8.
6. A copolymer as claimed in claim 1 wherein .delta.(MS)/.delta.(P)
is greater than 0.65.
7. A copolymer as claimed in claim 6 wherein .delta.(MS)/.delta.(P)
is greater than 0.80.
8. A copolymer as claimed in claim 6 wherein .delta.(MS)/.delta.(P)
is in the range greater than 0.65 to less than 1.4.
9. A. copolymer as claimed in claim 6 wherein
.delta.(MS)/.delta.(P) is in the range from 0.8 to 1.2.
10. A copolymer of ethylene and one or more alpha olefins
containing from three to twenty carbon atoms said copolymer having:
a) a long chain branching g' value of less than or equal to 0.9 and
b) a value of the derivative function .delta.(MS)/.delta.(log{dot
over (.gamma.)}) of greater than 7.5 wherein MS is the melt
strength of the copolymer in cN and {dot over (.gamma.)} is the
shear rate of the copolymer in secs.sup.-1.
11. A copolymer as claimed in claim 10 wherein g' is less than or
equal to 0.8
12. A copolymer as claimed in claim 10 wherein g' is in the range
0.5 to 0.9.
13. A copolymer as claimed in claim 12 wherein g' is in the range
0.55 to 0.85.
14. A copolymer as claimed in claim 13. wherein g' is in the range
0.65 to 0.8.
15. A copolymer as claimed in claim 10 wherein
.delta.(MS)/.delta.(logy) is greater than 8.0.
16. A copolymer as claimed in claim 10 wherein
.delta.(MS)/.delta.(log{dot over (.gamma.)}) is from 8.0 to
12.0.
17. A homopolymer of ethylene or a copolymer of ethylene and one or
more alpha olefins containing from three to twenty carbon atoms
said homopolymer or copolymer having: a) a value of the derivative
function .delta.(MS)/.delta.(P) of greater than 0.6 and b) an
M.sub.w/M.sub.n value of in the case of the copolymer less than 8
and in the case of the homopolymer less than 6 wherein MS is the
melt strength of the copolymer or homopolymer in cN and P is the
extrusion pressure of the copolymer or homopolymer in MPa and
M.sub.w/M.sub.n is the ratio of weight average molecular weight to
number average molecular weight of the copolymer or homopolymer as
measured by gel permeation chromatography.
18. A homopolymer or copolymer as claimed in claim 17 wherein
.delta.(MS)/.delta.(P) is greater than 0.8.
19. A homopolymer or copolymer as claimed in claim 18 wherein
.delta.(MS)/.delta.(P) is greater than 0.75.
20. A homopolymer or copolymer as claimed in claim 17 wherein
.delta.(MS)/.delta.(P) is in the range greater than 0.8 to 1.2.
21. A homopolymer or copolymer as claimed in claim 17 wherein the
M.sub.w/M.sub.n value is less than 6.
22. A homopolymer of ethylene or a copolymer of ethylene and one or
more alpha olefins containing from three to twenty carbon atoms
said homopolymer or copolymer having: a) a value of the derivative
function .delta.(MS)/.delta.(log{dot over (.gamma.)}) of greater
than 7.5 and b) an M.sub.w/M.sub.n value of less than 6.5 wherein
MS is the melt strength of the copolymer in cN and {dot over
(.gamma.)} is the shear rate of the copolymer in secs.sup.-1 and
M.sub.w/M.sub.n is the ratio of weight average molecular weight to
number average molecular weight as measured by gel permeation
chromatography.
23. A homopolymer or copolymer as claimed in claim 22 wherein
.delta.(MS)/.delta.(log{dot over (.gamma.)}) is greater than
8.0
24. A homopolymer or copolymer as claimed in claim 22 wherein
.delta.(MS)/.delta.(logy) is from 8.0 to 12.0.
25. A homopolymer of ethylene or a copolymer of ethylene and one or
more alpha olefins containing from three to twenty carbon atoms
said homopolymer or copolymer having a long chain branching g'
value of between about 0.6 and about 0.9.
26. A homopolymer or copolymer as claimed in claim 25 wherein g' is
from 0.65 to 0.8.
27. A copolymer of ethylene and one or more alpha-olefins
containing from three to twenty carbon atoms said copolymer having:
(a) a long chain branching g' value of less than or equal to 0.9
and (b) a value of the derivative function .delta.(MS)/.delta.(log
{dot over (.gamma.)}) and a M.sub.w/M.sub.n satisfy the
relationship: log[.delta.(MS)/.delta.(log {dot over
(.gamma.)})].gtoreq.0.6 log(Mw/Mn)+0.3 wherein Mw/Mn is the ratio
of weight average molecular weight to number molecular weight as
measured by gel chromatography.
28. A copolymer of ethylene and one or more alpha-olefins
containing from three to twenty carbon atoms said copolymer having:
(a) a long chain branching g' value of less than or equal to 0.9
and (b) a value of the derivative function .delta.(MS)/.delta.(P)
and Mw/Mn which satisfy the relationship:
.delta.(MS)/.delta.(P).gtoreq.0.12 Mw/Mn wherein Mw/Mn is the ratio
of weight average molecular weight to number molecular weight as
measured by gel chromatography.
29. A copolymer of ethylene and one or more alpha-olefins
containing from three to twenty carbon atoms said copolymer having:
(a) an flow activation energy, Ea, of value greater than or equal
to 40 kJ/mol and (b) a value of the derivative function
.delta.(MS)/.delta.(log {dot over (.gamma.)}) and a Mw/Mn which
satisfy the relationship: log[.delta.(MS)/.delta.(log {dot over
(.gamma.)})].gtoreq.0.6 log(Mw/Mn)+0.3 wherein Mw/Mn is the ratio
of weight average molecular weight to number molecular weight as
measured by gel chromatography.
30. A copolymer of ethylene and one or more alpha-olefins
containing from three to twenty carbon atoms said copolymer having:
(a) an flow activation energy, Ea, of value greater than or equal
to 40 kJ/mol and (b) a value of the derivative function
.delta.(MS)/.delta.(P) and Mw/Mn which satisfy the relationship:
.delta.(MS)/.delta.(P).gtoreq.0.12 Mw/Mn wherein Mw/Mn is the ratio
of weight average molecular weight to number molecular weight as
measured by gel chromatography.
31. A copolymer of ethylene and one or more alpha-olefins
containing from three to twenty carbon atoms said copolymer having:
(a) a long chain branching g' value of less than or equal to 0.9
and (b) a value of the derivative function .delta.(MS)/.delta.(P)
and a flow activation energy Ea satisfy the relationship:
Log[.delta.(MS)/.delta.(P)].gtoreq.3.7-2.4 log(Ea) wherein Ea is
measured by dynamic rheometry.
32. A copolymer of ethylene and one or more alpha-olefins
containing from three to twenty carbon atoms said copolymer having:
(a) a long chain branching g' value of less than or equal to 0.9
and (b) a value of the derivative function
.delta.(MS)/.delta.(log{dot over (.gamma.)}) and a flow activation
energy Ea satisfy the relationship: Log[.delta.(MS)/.delta.(log{dot
over (.gamma.)})].gtoreq.2.75-1.25 log(Ea) wherein Ea is measured
by dynamic rheometry.
33. A homopolymer or copolymer as claimed in any one of claims 1,
10, 17, 22, 25, 27-32 obtainable by continuously polymerising
ethylene alone or with one or more alpha olefins having from three
to twenty carbon atoms in the gas phase in a single reactor
containing a fluidised bed of polymer particles said polymerisation
being carried out in the presence of a single metallocene
catalyst.
34. A homopolymer or copolymer as claimed in claim 33 obtainable by
continuously polymerising ethylene alone or with one ore more alpha
olefins having from three to twenty carbon atoms in the gas phase
in a reaction system comprising a single reactor containing a
fluidised bed of polymer particles, a recycle loop connecting the
inlet and outlet of the reactor and means for withdrawing the
homopolymer or copolymer either continuously or periodically from
the reactor whilst polymerisation is occurring, said polymerisation
being carried out in the presence of a single metallocene
catalyst.
35. A homopolymer or copolymer as claimed in 33 or claim 34
obtainable by continuously polymerising ethylene alone or with one
or more alpha olefins having from three to twenty carbon atoms in
the gas phase in a single reactor containing a fluidised bed of
polymer particles said polymerisation being carried out in the
presence of a single metallocene catalyst having the following
general formula: 3wherein M is titanium, zirconium or hafnium, D is
a stable conjugated diene optionally substituted with one or more
hydrocarbyl groups, silyl groups, hydrocarbylsilyl groups,
silylhydrocarbyl groups or mixtures thereof, said D having from 4
to 40 non-hydrogen atoms and forming a .pi.-complex with M, Z is a
bridging group comprising an alkylene group having 1-20 carbon
atoms or a dialkyl silyl- or germanyl group or alkyl phosphine or
amino radical, R is hydrogen or alkyl having from 1 to 10 carbon
atoms and x is 1-6.
36. A homopolymer or copolymer as claimed in 33 or claim 34
obtainable by continuously polymerising ethylene alone or with one
or more alpha olefins having from three to twenty carbon atoms in
the gas phase in a single reactor containing a fluidised bed of
polymer particles said polymerisation being carried out in the
presence of a single metallocene catalyst having the following
general formula: 4wherein M is titanium, zirconium or hafnium in
the +2 oxidation state, D is a stable conjugated diene selected
from the group consisting of s-trans-.eta..sup.4,4-dipheny-
l-1,3-butadiene; s-trans-.eta..sup.4-3-methyl-1,3-pentadiene;
s-trans-.eta..sup.4-1,4-dibenzyl-1,3-butadiene;
s-trans-.eta..sup.4-2,4-h- exadiene;
s-trans-.eta..sup.4-1,4-ditolyl-1,3-butadiene;
s-trans-.eta..sup.4-1,4-bis(trimethylsilyl)-1,3-butadiene;
scis-.eta..sup.4-1,4-diphenyl-1,3-butadiene;
s-cis-.eta..sup.4-3-methyl-1- ,3-pentadiene;
s-cis-.eta..sup.4-2,4-hexadiene; s-cis-.eta..sup.42,4-hexad- iene;
s-cis-.eta..sup.41,3-pentadiene;
s-cis-.eta..sup.4-1,4-ditolyl-1,3-b- utadiene; and
s-cis-.eta..sup.4-1,4-bis(trimethylsilyl)-1,3-butadiene, said s-cis
diene group forming a .pi.-complex as defined herein with the
metal. Z is a bridging group comprising an alkylene group having
1-20 carbon atoms or a dialkyl silyl- or germanyl group or alkyl
phosphine or amino radical, R is hydrogen or alkyl having from 1 to
10 carbon atoms and x is 1-6.
37. A homopolymer or copolymer as claimed in 33 or claim 34
obtainable by continuously polymerising ethylene and, in the case
of copolymerising, one ore more alpha olefins having from three to
twenty carbon atoms in the gas phase in a single reactor containing
a fluidised bed of polymer particles said polymerisation being
carried out in the presence of a single metallocene catalyst having
the following formula: 5
38. A film exhibiting a dart impact value measured by ASTM D-1709
(Method A) in the range about greater than 100 and up to about 2000
comprising a copolymer as claimed in claims 1, 10, 17, 22, 25,
27-32.
39. A film exhibiting a dart impact value measured by ASTM-D1709
(Method A) in the range about greater than 100 and up to about 2000
comprising a copolymer of ethylene and an alpha-olefin of from 3 to
10 carbon atoms which has a density of from 0.910-0.930, a
I.sub.21/I.sub.2 value of .gtoreq.35, a long chain branching g'
value of less than or equal to 0.9 and a value of the derivative
function .delta.(MS)/.delta.(P) of greater than 0.6.
40. A film exhibiting a dart impact value measured by ASTM-D 1709
(Method A) in the range about greater than 100 and up to about 2000
comprising a copolymer of ethylene and an alpha-olefin of from 3 to
10 carbon atoms which has a density of from 0.910-0.930, a
I.sub.21/I.sub.2 value of .gtoreq.35, a long chain branching g'
value of less than or equal to 0.9 and a value of the derivatie
function .delta.(MS)/.delta.(P) and flow activation energy Ea
satisfy the relationship log[.delta.(MS)/.delta.(P)]-
.gtoreq.3.7-2.4 log(Ea).
Description
[0001] The present invention relates to novel polymers and in
particular to novel copolymers having a broad molecular weight
distribution, toughness and improved processability.
[0002] In recent years there have been many advances in the
production of polyolefin copolymers due to the introduction of
metallocene catalysts. Metallocene catalysts offer the advantage of
generally higher activity than traditional Ziegler catalysts and
are usually described as catalysts which are single-site in nature.
Because of their single-site nature the polyolefin copolymers
produced by metallocene catalysts often are quite uniform in their
molecular structure. For example, in comparison to traditional
Ziegler produced materials, they have relatively narrow molecular
weight distributions (MWD) and narrow Short Chain Branching
Distribution (SCBD). Although certain properties of metallocene
products are enhanced by narrow MWD, difficulties are often
encountered in the processing of these materials into useful
articles and films relative to Ziegler produced materials. In
addition, the uniform nature of the SCBD of metallocene produced
materials does not readily permit certain structures to be
obtained.
[0003] An approach to improving processability has been the
inclusion of long chain branching (LCB), which is particularly
desirable from the viewpoint of improving processability without
damaging advantageous properties. U.S. Pat. Nos. 5,272,236;
5,278,272; 5,380,810; and EP 659,773, EP 676,421, relate to the
production of polyolefins with long chain branching.
[0004] Another approach is the addition of the polymer processing
aids to the polymer prior to fabrication into films or articles.
This requires extra processing and is expensive.
[0005] A different approach to the problem has been to make
compositions which are blends or mixtures of individual polymeric
materials with the aim being to maximise the beneficial properties
of given component while minimising its processing problems. This
also requires extra processing which increases the cost of
materials produced. U.S. Pat. Nos. 4,598,128; 4,547,551; 5,408,004;
5,382,630; 5,383,631; and 5,326,602; and WO 94/22948 and WO
95/25141 relate to typical blends.
[0006] Another way to provide a solution for the processability
problems and to vary SCBD has been the development of various
cascade processes, where the material is produced by a series of
polymerizations under different reactor conditions, such as in a
series of reactors. Essentially, a material similar in some ways to
a blend is produced, with a modality greater than one for various
physical properties, such as the molecular weight distribution.
While polyolefin compositions with superior processability
characteristics can be produced this way, these methods are
expensive and complicated relative to the use of a single reactor.
Processes of interest are disclosed in U.S. Pat. No. 5,442,018, WO
95/26990, WO 95/07942 and WO 95/10548.
[0007] Another potentially feasible approach to improving
processability and varying SCBD has been to use a multicomponent
catalyst. In some cases, a catalyst which has a metallocene
catalyst and a conventional Ziegler-Natta catalyst on the same
support are used to produce a multimodal material. In other cases
two metallocene catalysts have been used in polyolefin
polymerizations. Components of different molecular weights and
compositions are produced in a single reactor operating under a
single set of polymerisation conditions. This approach is difficult
from the point of view of process control and catalyst preparation.
Catalyst systems of interest are disclosed in WO 95/11264 and EP
676,418.
[0008] WO96/04290 teaches the use of the preferred metallocene
complexes of this invention to make ethylene copolymers. In
particular, Examples 44 and 45 teach the preparation of polymer
using gas-phase techniques. The examples teach only operation for a
hour or less in batch mode and no details of the original polymer
bed composition is given.
[0009] U.S. Pat. No. 5,462,999 and U.S. Pat. No. 5,405,922 teaches
the preparation of ethylene copolymers in the gas-phase using a
silica supported metallocene catalyst. It is believed, however,
that the products produced by following the examples will not
contain long chain branching and in particular will have lower
values for the parameters .delta.(MS)/.delta.(P) and
.delta.(MS)/.delta.(log{dot over (.gamma.)}) than is claimed
herein.
[0010] EP 676421 also teaches the preparation of copolymers in the
gas phase sing a supported metallocene catalyst. The products
produced in the examples of this patent in general also have lower
values for the parameters .delta.(MS)/.delta.(P) and
.delta.(MS)/.delta.(logy) than is claimed herein.
[0011] EP 452920 and EP495099 teach the production of ethylene
copolymers using metallocene catalysts. Once again it is believed
that the examples contained therein will not produce products with
some or all of the desirable characteristics mentioned below
[0012] It would be desirable to be able to produce a polyolefin
copolymer composition which is very easy to process and which is
produced using a single metallocene catalyst system preferably
supported in a polymerisation process using a single reactor,
preferably gas phase, operating semi-continuously or, preferably,
continuously under a single set of reactor conditions.
[0013] It would also be desirable to produce polymers which have
the processability and impact strength similar to highly branched
low density polyethylene (LDPE).
[0014] It would also be highly desirable to produce polymers having
the above properties which may be suitable for use in low density
polyethylene film applications.
[0015] We have now found copolymers of ethylene and alpha olefins
may be prepared which have improved processability and which
exhibit specific melt strength characteristics. Such copolymers are
advantageously prepared using a single metallocene catalyst system
using a single gas-phase, fluidised bed reactor.
[0016] Thus according to a first aspect of the present invention
there is provided a copolymer of ethylene and one or more alpha
olefins containing from three to twenty carbon atoms said copolymer
having:
[0017] a) a long chain branching g' value of less than or equal to
0.9 and
[0018] b) a value of the derivative function .delta.(MS)/.delta.(P)
of greater than 0.6 wherein MS is the melt strength of the
copolymer in cN and P is the extrusion pressure of the copolymer in
MPa.
[0019] In a second aspect of the invention there is provided a
copolymer of ethylene and one or more alpha olefins containing from
three to twenty carbon atoms said copolymer having:
[0020] a) a long chain branching g' value of less than or equal to
0.9 and
[0021] b) a value of the derivative function
.delta.(MS)/.delta.(logy) of greater than 7.5 wherein MS is the
melt strength of the copolymer in cN and {dot over (.gamma.)} is
the shear rate of the copolymer in secs.sup.-1.
[0022] Also provided by the present is a homopolymer of ethylene or
a copolymer of ethylene and one or more alpha olefins containing
from three to twenty carbon atoms said homopolymer or copolymer
having:
[0023] a) a value of the derivative function .delta.(MS)/.delta.(P)
of greater than 0.6 and
[0024] b) an M.sub.w/M.sub.n value of in the case of the copolymer
less than 8 and in the case of the homopolymer less than 6
[0025] wherein MS is the melt strength of the copolymer or
homopolymer in cN and P is the extrusion pressure of the copolymer
or homopolymer in MPa and M.sub.w/M.sub.n is the ratio of weight
average molecular weight to number average molecular weight of the
copolymer or homopolymer as measured by gel permeation
chromatography.
[0026] The derivative function value .delta.(MS)/.delta.(P) is
preferably .gtoreq.0.75 and more preferably .gtoreq.0.8.
[0027] In a further aspect of the present invention as herein
described there is provided a homopolymer of ethylene or a
copolymer of ethylene and one or more alpha olefins containing from
three to twenty carbon atoms said homopolymer or copolymer
having:
[0028] a) a value of the derivative function
.delta.(MS)/.delta.(logy) of greater than 7.5 and
[0029] b) an M.sub.w/M.sub.n value of less than 6.5 wherein MS is
the melt strength of the copolymer in cN and {dot over (.gamma.)}
is the shear rate of the copolymer in secs.sup.-1 and
M.sub.w/M.sub.n is the ratio of weight average molecular weight to
number average molecular weight as measured by gel permeation
chromatography.
[0030] Another aspect of the present invention is provided by a
homopolymer of ethylene or a copolymer of ethylene and one or more
alpha olefins containing from three to twenty carbon atoms said
homopolymer or copolymer having a long chain branching g' value of
between about 0.6 and about 0.9. The homopolymers and copolymers of
this aspect of the invention may also have either or both of (a) a
value of the derivative function .delta.(MS)/.delta.(P) of greater
than 0.6 or (b) a value of the derivative function
.delta.(MS)/.delta.(log{dot over (.gamma.)}) of greater than 7.5
wherein MS is the melt strength of the copolymer in cN and P is the
extrusion pressure of the copolymer in MPa and {dot over (.gamma.)}
is the shear rate of the copolymer in secs.sup.-1.
[0031] The homopolymers and copolymers of the present invention
which are described above exhibit considerable rate advantages when
processed for commercial use. Thus relative to those products known
to date the homopolymers and copolymers of the present invention
can be processed at lower melt temperature with lower melt pressure
and lower power consumption than for previously known polymers of
equivalent melt index. Alternatively for the same external
conditions higher throughputs can be achieved.
[0032] The long chain branch parameter, g' may be calculated from
gel permeation chromatography data (GPC) on-line viscometry
data.
[0033] Although the present invention is not limited in all its
aspects to homopolymers and copolymers possessing long chain
branches, it is preferable that all the homopolymers and copolymers
of the present invention have this feature. In such cases, the
value of the long chain branching parameter g' for all the
copolymers of the present invention should be less than 0.9,
preferably less than 0.8, or alternatively preferably greater than
0.5. Preferably the parameter lies in the range about 0.5 to about
0.9 preferably in the range 0.55 to 0.85 more preferably in the
range about 0.6 to about 0.8 and most preferably in the range 0.65
to 0.8. For the homopolymers the g' parameter should be in
the-range about 0.6 to about 0.9 more preferably 0.6 to 0.8 and
most preferably 0.65 to 0.8.
[0034] As far as the melt strength (MS), extrusion pressure (P) and
shear rate ({dot over (.gamma.)}) parameters are concerned, the
methods of measuring these for polymers are well known to those
skilled in the art. By measuring the MS parameter it is possible to
construct for example graphical relationships which allow the two
derivative functions .delta.(MS)/.delta.(P) and
.delta.(MS)/.delta.(log{dot over (.gamma.)}) to be calculated. The
melt strength (MS) and extrusion pressure at shear rate of 500/S
may also be calculated in this way. Although the present invention
is not limited in all its aspects to homopolymers and copolymers in
which either or both of these derivative functions is a critical
parameter, it is preferable that all the homopolymers and
copolymers of the present invention meet at least one and
preferably both of the following numerical constraints. As far as
the derivative function .delta.(MS)/.delta.(P) is concerned this
should be greater than 0.6, desirably greater than 0.65, more
desirably greater than 0.7 and most desirably greater than 0.80.
Preferably the value of the derivative function
.delta.(MS)/.delta.(P) should be in the range greater than 0.6 to
less than 1.5 more preferably from 0.65 to less than 1.4, even more
preferably from 0.7 to 1.3 and most preferably from 0.8 to 1.2.
[0035] The derivative function .delta.(MS)/.delta.(log{dot over
(.gamma.)}) should be greater than 7.5 desirably 7.75 or greater
and more desirably 8.0 or greater. Preferably the value of this
derivative function lies in the range greater than 7.5 to 15.0,
more preferably from 7.75 to 13.0 and most preferably 8.0 to
12.0.
[0036] The copolymers according to the present invention may also
be defined with respect to activation energy Ea as measured by
dynamic rheometry. Thus according to another aspect of the
invention there is provided a copolymer of ethylene and one or more
alpa olefins containing from three to twenty carbon atoms said
copolymer having:
[0037] (a) an activation energy, Ea, of value greater than or equal
to 40 kJ/mol and
[0038] (b) a value of the derivative function
.delta.(MS)/.delta.(P) of greater than 0.6
[0039] wherein MS is the melt strength of the copolymer in cN and P
is the extrusion pressure of the copolymer in MPa. Ea is measured
by dynamic rheometry.
[0040] Preferably the value of the derivative function
.delta.(MS)/.delta.(P) is greater than 0.65 and most preferably
greater than 0.75.
[0041] The derivative function may also be represented by the
relationship
0.65.ltoreq..delta.(MS)/.delta.(P).ltoreq.1.4
[0042] and preferably
0.7.ltoreq..delta.(MS)/.delta.(P).ltoreq.1.2.
[0043] In a further aspect of the invention there is provided a
copolymer of ethylene and one or more alpa olefins containing from
three to twenty carbon atoms said copolymer having:
[0044] (a) an activation energy, Ea of value greater than or equal
to 40 kJ/mol and
[0045] (b) a value of the derivative function
.delta.(MS)/.delta.(log {dot over (.gamma.)}) of greater than
7.5
[0046] wherein MS is the melt strength of the copolymer in cN and
.gamma. is the shear rate of the copolymer in sec.sup.-1. Ea is
measured by dynamic rheometry.
[0047] Preferably the value of the derivative function
.delta.(MS)/.delta.(log{dot over (.gamma.)}) is greater than 7.5
and most preferably greater than 8.0.
[0048] The derivative function may also be represented by the
relationship
8.0.ltoreq..delta.(MS)/.delta.(log {dot over
(.gamma.)}).ltoreq.12.
[0049] In normal polymer extrusion, for example in film processing,
the throughput rate is usually high and the corresponding shear
rate is expected to be in region of, or greater than, 500/s. The
shear. viscosity .eta.(500/s), extrusion pressure P(500/s) and melt
strength MS(500/s), measured at shear rate of 500/s, using both the
capillary rheometer and Rheotens, have thus been used to
characterise the processability of polymer (Table 2). Although the
present invention is not limited in all its aspects to homopolymers
and copolymers in which these parameters are critical, it is
preferable that all the homopolymers and copolymers of the present
invention should have a MS(500/s) be greater than 13 cN desirably
15 cN and more desirably 16 cN or greater; a P(500/s) value should
be less than or equal to 19 MPa desirably 18 MPa and more desirably
17.5 MPa or less; a .eta.(500/s) should be less than or equal to
430 Pa.s desirably 400 Pa.s and more desirably 300 Pa.s or
less.
[0050] In another aspect of the invention there is provided a
copolymer of ethylene and one or more alpha olefins containing from
three to twenty carbon atoms said copolymer having:
[0051] (a) a long chain branching g' value of less than or equal to
0.9 and
[0052] (b) a melt strength, MS(500/s) and extrusion pressure,
P(500/s) satisfying the relationship:
MS(500/s)> or =P(500/s)-4.5
MS(500/s)> or =P(500/s)-4 desirably
MS(500/s)> or =P(500/s)-3.5 more desirably
[0053] wherein MS is the melt strength of the copolymer in cN and P
is the extrusion pressure of the copolymer in MPa, all determined
at shear rate of 500/s using a Rosand Capillary Rheometer and a
Gottfert Rheotens.
[0054] In a further aspect of the invention there is provided a
copolymer of ethylene and one or more alpha olefins containing from
three to twenty carbon atoms said copolymer having:
[0055] (a) an activation energy, Ea, of value greater than or equal
to 40 kJ/mol and
[0056] (b) a melt strength, MS(500/s) and extrusion pressure,
P(500/s) satisfying relationship:
MS(500/s)> or =P(500/s)-4.5
MS(500/s)> or =P(500/s)-4 desirably
MS(500/s)> or =P(500/s)-3.5 more desirably
[0057] wherein MS is the melt strength of the copolymer in cN and P
is the extrusion pressure of the copolymer in MPa, all determined
at shear rate of 500/s using a Rosand Capillary Rheometer and a
Gottfert Rheotens. Ea is measured by dynamic rheometry.
[0058] Another aspect of the invention there is provided a
copolymer of ethylene and one or more alpha olefins containing from
three to twenty carbon atoms said copolymer having:--
[0059] (a) a melt strength, MS(500/s) and Mw/Mn value satisfying
relationship:
MS(500/s)> or =1.13(Mw/Mn)+9.5, and
[0060] (b) a melt strength, MS(500/s) and extrusion pressure,
P(500/s) satisfying relationship:
MS(500/s)> or =P(500/s)-4.5
MS(500/s)> or =P(500/s)-4 desirably
MS(500/s)> or =P(500/s)-3.5 more desirably
[0061] wherein MS is the melt strength of the copolymer in cN and P
is the extrusion pressure of the copolymer in MPa, all determined
at shear rate of 500/s using a Rosand Capillary Rheometer and a
Gottfert Rheotens. Mw/Mn is the ratio of weight average molecular
weight to number molecular weight as measured by gel
chromatography.
[0062] Another aspect of the invention there is provided a
copolymer of ethylene and one or more alpha olefins containing from
three to twenty carbon atoms said copolymer having:--
[0063] (a) a melt strength, MS(500/s) and Mw/Mn value satisfying
relationship:
MS(500/s)> or =1.13(Mw/Mn)+9.5, and
[0064] (b) a melt strength, MS(500/s) and shear viscosity,
.eta.(500/s) satisfying relationship:
MS(500/s)> or =0.053.eta.(500/s)-4.0
MS(500/s)> or =0.053.eta.(500/s)-3.5 desirably
MS(500/s)> or =0.053.eta.(500/s)-3.0 more desirably
[0065] wherein MS is the melt strength of the copolymer in cN and
.eta. is the shear viscosity of the copolymer in Pa.s, all
determined at shear rate of 500/s using a Rosand Capillary
Rheometer and a Gottfert Rheotens. Mw/Mn is the ratio of weight
average molecular weight to number molecular weight as measured by
gel chromatography.
[0066] The parameter M.sub.w/M.sub.n is calculated from
corresponding values for the weight average molecular weight
M.sub.w and the number average molecular weight M.sub.n in turn
obtained from gel permeation chromatography. Although the present
invention is not limited in all its aspects to homopolymers and
copolymers in which this parameter is critical, it is preferable
that all the homopolymers and copolymers of the present invention
should have an M.sub.w/M.sub.n value of less than 8 preferably less
than 7 more preferably less than 6.5 and most preferably less than
6.
[0067] Turning to other characteristics of the homopolymers and
copolymers of the present invention, the density of these materials
should be in the range 0.8 to 10.0 preferably 0.85 to 0.95 and most
preferably 0.91 to 0.93. It is preferable that the melt flow ratio
of the polymer measured at a load of 2.16 kg by standard techniques
is in the range 0.01 to 100 and more preferably in the range 0.1 to
10 dg.min.sup.-1. Typically the weight average molecular weight of
the material is in the range 25,000 to 500,00 preferably 50,000 to
250,000 and most preferably 80,000 to 200,000. For the copolymers
of the present invention it is preferable that they are comprised
of between 2 and 30 weight %, most preferably between 5 and 20
weight % of units derived from the precursor comonomer.
[0068] The most preferable homopolymers and copolymers of the
present invention appear to be characterised by molecular weight
distributions (as measured by gel permeation chromatography) which
show varying degrees of deviation from unimodality. In some
instances these non unimodal characteristics are manifested in
clear bimodality or even more complex distributions indicative of
even higher orders of modality. This property is one which in
particular has been seen before in connection with single site
catalyst operating in a single reaction environment.
[0069] The homopolymers and copolymers of the present invention are
suitably prepared by continuous polymerisation of the required
monomer(s) in the presence of a single metallocene catalyst system
in a single reactor. By the term continuous polymerisation is meant
a process which for at least a significant period of time is
operated with continuous feeding of the monomer(s) to the reactor
in parallel with continuous or periodic withdrawing of homopolymer
or copolymer product. Preferably the continuous polymerisation is
effected in the gas phase at elevated temperature in the presence
of a fluidised bed of polymer particles and continuous recycle of
unreacted monomer(s) around a loop joining the inlet and outlet of
the reactor containing the fluidised bed. Examples of two possible
approaches are described in EP 89961, U.S. Pat. No. 5,352,7947 and
U.S. Pat. No. 5,541,270 the complete texts of which are herein
incorporated by reference. EP 699213 also illustrates a possible
approach and again the complete text of this publication is
incorporated by reference. The metallocene catalyst system
comprises a metallocene complex and activating cocatalyst which in
the case of a gas phase process is preferably supported on an inert
carrier (e.g. silica). The catalyst system can be optionally
prepolymerised and/or utilised in the presence of a Group IIIa
metal alkyl scavenger such as an aluminium alkyl.
[0070] Suitable metallocene complexes which can be used to prepare
the homopolymers and copolymers of the present invention comprise
those organometallic complexes of the Group IVB (i.e. the titanium
group) having between one and three .eta..sup.5 bonded
cylopentadienyl indenyl or fluorenyl ligands. Whilst these ligands
may be unsubsituted or substituted at one or more of their carbon
atoms with a substituent, including but not limited to alkyl groups
having from one and ten carbon atoms, the most preferred
metallocene complexes are those where at least two of the
cyclopentadienyl, indenyl and fluorenyl ligands are connected
together by a divalent bridging group e.g. an alkylene group having
from one to eight carbon atoms or the corresponding silylene,
germanylene derivatives. These alkylene, silylene and germanylene
groups can in turn be substituted on the carbon and silicon
backbone. Alternatively bridging can be effected by using a
divalent phoshino or amino group the third valence of each being
satisfied by an alkyl group having between one and eight carbons or
phenyl (either substituted or unsubstituted).
[0071] The indenyl or fluorenyl ligands in such complexes may also
be in the form of their hydrogenated derivatives.
[0072] Most preferred metallocene complexes are those having the
following general formula: 1
[0073] wherein
[0074] M is titanium, zirconium or hafnium,
[0075] D is a stable conjugated diene optionally substituted with
one or more hydrocarbyl groups, silyl groups, hydro carbylsily
groups, silylhydrocarbyl groups or mixtures thereof, or may contain
a Lewis base functionality, said D having from 4 to 40 non-hydrogen
atoms and forming a .pi.-complex with M,
[0076] Z is a bridging group comprising an alkylene group having
1-20 carbon atoms or a dialkyl silyl- or germanyl group or alkyl
phosphine or amino radical,
[0077] R is hydrogen or alkyl having from 1-10 carbon atoms, and x
is 1-6.
[0078] Most preferred metallocene complexes in this family are
those where, as evidenced by X-ray diffraction or NMR, the D ligand
is .pi.-bonded to the M atom in an .eta..sup.3 fashion. Such
metallocene complexes are characterised by the M atom being in the
+2 oxidation state.
[0079] Preferred complexes are those wherein M is zirconium and Z
is ethylene (CH.sub.2CH.sub.2).
[0080] The D ligand is most preferably chosen from the group:
[0081] s-trans-.eta..sup.4,4-diphenyl-1,3-butadiene;
s-trans-.eta..sup.4-3-methyl-1,3-pentadiene;
s-trans-.eta..sup.4-1,4-dibe- nzyl-1,3-butadiene;
s-trans-.eta..sup.4-2,4-hexadiene;
s-trans-.eta..sup.4-1,4-ditolyl-1,3-butadiene;
s-trans-.eta..sup.4-1,4-bi- s(trimethylsilyl)-1,3-butadiene;
scis-.eta..sup.4-1,4-diphenyl-1,3-butadie- ne;
s-cis-.eta..sup.4-3-methyl-1,3-pentadiene;
s-cis-.eta..sup.4-2,4-hexad- iene; s-cis-.eta..sup.42,4-hexadiene;
s-cis-.eta..sup.41,3-pentadiene;
s-cis-.eta..sup.4-1,4-ditolyl-1,3-butadiene; and
s-cis-.eta..sup.4-1,4-bi- s(trimethylsilyl)-1,3-butadiene, said
s-cis diene group forming a .pi.-complex as defined herein with
the, metal.
[0082] Particularly suitable are externally substituted dienes in
particular the 1,4-diphenyl substituted butadienes.
[0083] The preparation of these complexes is extensively described
in WO 96/04290 which also lists examples of suitable
representatives for use in the present invention.
[0084] When the diene group D has a Lewis base functionality this
may be chosen from the following groups:
[0085] --NR.sub.2, --PR.sub.2, --AsR.sub.2, --OR, --SR
[0086] Particularly preferred dienes of this type are dialkylarmino
phenyl substituted dienes for example 1-phenyl-4 (N,N'-diethylamino
phenyl) 1,3-butadiene.
[0087] The most preferred complex is ethylene bis(indenyl)
zirconium (II) 1,4-diphenyl butadiene having the following
formula:-- 2
[0088] Also preferred is the hydrogenated analogue-ethylene
bis(tetrahydroindenyl) zirconium (II) 1,4-diphenyl butadiene.
[0089] The activating cocatalysts suitable for use with the above
metallocene complexes are preferably tri(hydrocarbyl) boranes in
particular trialkylboranes or triarylboranes. Most preferred
cocatalysts are perfluorinated tri(aryl) boron compounds and most
especially tris(pentafluorophenyl) borane. Other activators include
borate salts of a cation which is a Bronsted acid capable of
donating a proton to one of the ligands on the metallocene complex.
The potential scope of both these types of activators is
illustrated in WO 96/04290 the relevant sections of which are
herein incorporated by reference.
[0090] Another type of activator suitable for use with the
metallocene complexes of the present invention are the reaction
products of (A) ionic compounds comprising a cation and an anion
wherein the anion has at least one substituent comprising a moiety
having an active hydrogen and (B) an organometal or metalloid
compound wherein the metal or metalloid is from Groups 1-14 of the
Periodic Table.
[0091] Suitable activators of this type are described in WO
98/27119 the relevant portions of which are incorporated by
reference.
[0092] A particular preferred activator of this type is the
reaction product obtained from alkylammonium
tris(pentafluorophenyl) 4-(hydroxyphenyl) borates and
trialkylamines. For example a preferred activator is the reaction
product of bis(hydrogenated tallow alkyl) methyl ammonium tris
(pentafluorophenyl) (4-hydroxyphenyl) borate and triethylamine.
[0093] The molar ratio of metallocene complex to activator employed
in the process of the present invention may be in the range 1:10000
to 100:1. A preferred range is from 1:5000 to 10:1 and most
preferred from 1:10 to 10:1.
[0094] The metallocene catalysts system suitable for use in the
present invention is most suitably supported. Typically the support
can be any organic or inorganic inert solid. However particularly
porous supports such as talc, inorganic oxides and resinous support
materials such as polyolefins which have well-known advantages in
catalysis are preferred. Suitable inorganic oxide materials which
may be used include Group 2, 13, 14 or 15 metal oxides such as
silica, alumina, silica-alumina and mixtures thereof Other
inorganic oxides that may be employed either alone or in
combination with the silica, alumina or silica-alumina are
magnesia, titania or zirconia. Other suitable support materials may
be employed such as finely divided polyolefins such as
polyethylene.
[0095] The most preferred support material for use with the
supported catalysts according to the process of the present
invention is silica. Suitable silicas include Crossfield ES70 and
Davidson 948 silicas.
[0096] It is preferable that the silica is dried before use and
this is typically carried out by heating at elevated temperatures
for example between 200 and 850 deg. C.
[0097] In another aspect of the present invention homopolymers of
ethylene or copolymers of ethylene and one or more alpha-olefins
containing from three to twenty carbon atoms may be prepared in the
presence of a single metallocene catalyst comprising a metallocene
complex and an activating cocatalyst wherein the activating
cocatalyst is not an alkyl aluminoxane for example methyl
aluminoxane (MAO).
[0098] In such cases there is thus provided a copolymer of ethylene
and one or more alpha-olefins containing from three to twenty
carbon atoms said copolymer having:
[0099] (a) a long chain branching g' value of less than or equal to
0.9 and
[0100] (b) a value of the derivative function
.delta.(MS)/.delta.(log {dot over (.gamma.)}) and a Mw/Mn satisfy
the relationship:
log[.delta.(MS)/.delta.(log {dot over (.gamma.)})].gtoreq.0.6
log(Mw/Mn)+0.3
[0101] wherein Mw/Mn is the ratio of weight average molecular
weight to number molecular weight as measured by gel
chromatography.
[0102] Such polymers may also be defined by:--
[0103] (a) a long chain branching g' value of less than or equal to
0.9 and
[0104] (b) a value of the derivative function
.delta.(MS)/.delta.(P) and Mw/Mn which satisfy the
relationship:
.delta.(MS)/.delta.(P).gtoreq.0.12 Mw/Mn
[0105] wherein Mw/Mn is the ratio of weight average molecular
weight to number molecular weight as measured by gel
chromatography.
[0106] The polymers may also be defined with respect to the flow
activation energy Ea as follows:--
[0107] (a) an flow activation energy, Ea, of value greater than or
equal to 40 kJ/mol and
[0108] (b) a value of the derivative function
.delta.(MS)/.delta.(log {dot over (.gamma.)}) and a Mw/Mn which
satisfy the relationship:
log[.delta.(MS)/.delta.(log {dot over (.gamma.)})].gtoreq.0.6
log(Mw/Mn)+0.3
[0109] wherein Mw/Mn is the ratio of weight average molecular
weight to number molecular weight as measured by gel
chromatography. Ea is measured by dynamic rheometry. Alternatively
the polymers may be defined by:
[0110] (a) an flow activation energy, Ea, of value greater than or
equal to 40 kJ/mol and
[0111] (b) a value of the derivative unction .delta.(MS)/.delta.(P)
and Mw/Mn which satisfy the relationship:
.delta.(MS)/.delta.(P).gtoreq.0.12 Mw/Mn
[0112] wherein Mw/Mn is the ratio of weight average molecular
weight to number molecular weight as measured by gel
chromatography. Ea is measured by dynamic rheometry.
[0113] The polymer may be defined by:
[0114] (a) a long chain branching g' value of less than or equal to
0.9 and
[0115] (b) a value of the derivative function
.delta.(MS)/.delta.(P) and a flow activation energy Ea satisfy the
relationship:
Log[.delta.(MS)/.delta.(P)].gtoreq.3.7-2.4 log(Ea)
[0116] wherein Ea is measured by dynamic rheometry.
[0117] Such polymers may also be defined by:
[0118] (a) a long chain branching g' value of less than or equal to
0.9 and
[0119] (b) a value of the derivative function
.delta.(MS)/.delta.(log{dot over (.gamma.)}) and a flow activation
energy Ea satisfy the relationship:
Log[.delta.(MS)/.delta.(log{dot over (.gamma.)})].gtoreq.2.75-1.25
log(Ea)
[0120] wherein Ea is measured by dynamic rheometry.
[0121] The copolymers of the present invention are copolymers of
ethylene with one or more alpha-olefins having from three to twenty
carbon atoms. Preferably the alpha-olefin has between three and ten
carbon atoms most preferably three and eight. Examples of the most
preferred alpha olefins include 1-butene, 1-hexene,
4-methyl-1-pentene, 1-octene. Particular suitable are copolymers of
ethylene with 1-hexene or 4-methyl-1-pentene.
[0122] Fabricated articles made from the novel polymers of the
present invention may be prepared using conventional polyolefin
processing techniques. Suitable articles of this type include film
(eg cast, blown etc) fibres and moulded articles (eg produced using
injection moulding, blow moulding or rotomoulding processes).
[0123] Other useful compositions are also possible comprising the
novel polymers of the present invention and at least one other
natural or synthetic polymer. Such compositions may be formed by
conventional methods for example dry blending. Other suitable
processing techniques may be used to prepare such compositions
comprising the novel polymers of the present invention.
[0124] The novel polymers of the present invention may suitably be
used for the manufacture of films and specific details of the film
properties and given below in the examples.
[0125] In particular the novel polymers of the present invention
may be used to prepare films having a dart impact value as measured
by ASTM D 1709 (method A) of greater than 100 and up to about 2000.
Such films comprise copolymers of the invention of density
0.910-0.930, a I.sub.21/O.sub.2 value of .gtoreq.35 and a long
chain branching g.sup.1 value of less than or equal to 0.9. In
addition the copolymers exhibit the melt strength characteristics
defined in detail above.
[0126] In particular they exhibit a value of the derivative
function .delta.(MS)/.delta.(P) of >0.6. Alternatively they may
also exhibit a value of the derivative function
.delta.(MS)/.delta.(P) and flow activation Ea of
log[.delta.(MS)/.delta.(P)].gtoreq.3.7-2.4 log Ea.
[0127] Such polymers also exhibit a flow activation Ea of
.gtoreq.40.
[0128] The present invention will now be further illustrated with
reference to the following examples and Figures which represent the
preparation of copolymers according to the present invention and a
comparison with commercially available prior art materials.
[0129] FIG. 1 shows the variation in melt strength (MS) with
extrusion pressure at 190.degree. C.
[0130] FIG. 2 shows the variation in melt strength (MS) with shear
rate at 190.degree. C.
[0131] FIG. 3 shows the variation in .delta.(MS)/.delta.(P) with
melt flow rate (2.16 Kg) at 190.degree. C.
[0132] FIG. 4 shows the variation in .delta.(MS)/.delta.(log{dot
over (.gamma.)}) with melt flow rate (2.16 Kg) at 190.degree.
C.
[0133] FIG. 5 shows the variation in .delta.(MS)/.delta.(P) with
M.sub.w/M.sub.n at 190.degree. C.
[0134] FIG. 6 shows the variation in the
.delta.(MS)/.delta.(log{dot over (.gamma.)}) with M.sub.w/M.sub.n
at 190.degree. C.
[0135] FIG. 7 shows the variation in .delta.(MS)/.delta.(P) with
the long chain branching parameter g' at 190.degree. C.
[0136] FIG. 8 shows the variation in .delta.(MS)/.delta.(log{dot
over (.gamma.)}) with the long chain branching parameter g' at
190.degree. C.
[0137] FIG. 9 shows the variation in .delta.(MS)/.delta.(P) with
flow activation energy (Ea) at 190.degree. C.
[0138] FIG. 10 shows the variation in .delta.(MS)/.delta.(log{dot
over (.gamma.)}) with flow activation energy (Ea) at 190.degree.
C.
[0139] Table 2 sets out a range of relevant physical information
for seven examples according to the present invention and examples
of eleven commercially available or representative prior art
materials.
[0140] The terms `Exceed`, `Affinity`, and `Dowlex` are registered
trade marks and herein recognised as such. Affinity FM1570, Exceed
ML27MAX, Exceed 350D60, Dowlex 2045, NTA 101, LL7206AF, LL7209AA,
LD 5320AA, LD 531AA, and Borealis LE 6592 are all commercially
available products whose origin will be known to those skilled in
the art. EBI/Zr(IV)/MAO is an experimental material produced
according to EP 676421.
[0141] The following analytical procedures were used in order to
characterise the novel polymers of the present invention and to
compare said polymers with the prior art and commercially available
materials.
[0142] 1. Rheological Characterisation
[0143] 1.1 Capillary Rheometry
[0144] The shear capillary viscosities of the polymers were
measured at 190.degree. C., using a Rosand RH 7 twin-bore capillary
rheometer, with two 1.0 mm diameter dies: one with die length of 16
mm while the other has a (zero) die length of 0.25 mm. The die
entry angle for both dies is 190.degree.. All data are corrected
for the effects of die entry & exit pressures (Bagley
correction) and of non-Newtonian flow (Rabinowitsch correction).
The shear viscosity at shear rate of 500/S, .eta.(500/S) is then
extracted from the corrected flow curve.
[0145] 1.2 Rheotens Extensional Rheometry
[0146] The melt strength of the polymer is measured at 190.degree.
C., using a Gottfert Rheotens extensional rheometer in conjunction
with a Rosand RH 7 Capillary Rheometer. This is achieved by
extruding the polymer at a constant pressure (P) through a die of
1.5 mm diameter and 30 mm in length, with a 90.degree. entry angle.
Once a given extrusion pressure is selected, the piston of the
capillary rheometer will travel through its 15 mm diameter barrel
at a speed that is sufficient to maintain that pressure constant
using the constant pressure system of the rheometer. The nominal
wall shear rate ({dot over (.gamma.)}) for a given extrusion
pressure can then be computed for the polymer at the selected
pressure.
[0147] The extrudate is drawn with a pair of gear wheels at an
accelerating speed (V). The acceleration ranges from 0.12 to 1.2
cm/s.sup.2 depending on the flow properties of the polymer under
test. The drawing force (F) experienced by the extrudate is
measured with a transducer and recorded on a chart recorder
together with the drawing speed. The maximum force at break is
defined as melt strength (MS) at a constant extrusion pressure (P)
or at its corresponding extrusion rate (.gamma.). Three or four
extrusion pressures (6, 8, 12, 16 MPa) are typically selected for
each polymer depending on its flow properties. For each extrusion
pressure, a minimum of 3 MS measurements are performed and an
average MS value is then obtained.
[0148] The derivative functions of the extrusion pressure and shear
rate dependent melt strengths, .delta.(MS)/.delta.(P) and
.delta.(MS)/.gamma.(log {dot over (.gamma.)}), for each polymer are
computed from the slopes (by a least square line fitting) of the
plots of the average MS against pressure and against shear rate
respectively. The melt strength and extrusion pressure at shear
rate of 500/s, (MS(500/s), P(500/s) respectively, were also
computed from these plots. (See FIGS. 1-2).
[0149] 1.3 Melt Flow Rate (2.16 kg)
[0150] The melt flow rate (MFR) of the polymers was measured under
conditions which conform to ISO 1133 (1991) and BS 2782:PART
720A:1979 procedures. The weight of polymer extruded through a die
of 2.095 mm diameter, at a temperature of 190.degree. C., during a
600 second time period and under a standard load of 2.16 kg is
recorded.
[0151] 2 Molecular Structure Characterisation
[0152] Various techniques (eg .sup.13C NMR, GPC/LALLS,
GPC/intrinsic viscosity, GPC/on-line viscometry and Theological
flow activation energy, etc) have been developed to indicate the
presence of long chain branching in polymers.
[0153] 2.1 Molecular Weight Distribution (M.sub.w/M.sub.n) and Long
Chain Branching (LCB) Measurements by GPC/On-Line Viscometry.
[0154] Molecular weight distribution was determined by gel
permeation chromatography/on-line viscometry (GPC/OLV) using a
Waters 150CV. The method followed was based upon that described by
J. Lesec et al, Journal of Liquid Chromatography, 17, 1029 (1994).
It is well known to those skilled in the art that this technique
can provide an estimate of long chain branching (LCB) content as a
function of molecular weight. While it is possible to interpret the
data in terms of the number of long chain branches per 1000 carbon
atoms, an alternative approach is to interpret the data in terms of
the parameter g' which is the ratio of the measured intrinsic
viscosity to that of a linear polymer having the same molecular
weight. Linear molecules show g' of 1, while values less than 1
indicate the presence of LCB. As always, the reliability of LCB
determinations can be greatly strengthened by combining results
from several techniques rather then relying on a sole method.
[0155] Average values of g' were calculated from the equation
<g'>.sub.LCB=[.eta.]/[.eta.].sub.lin where
[.eta.]=.SIGMA.(w.sub.i[- .eta.].sub.i, and
[.eta.].sub.lin=.SIGMA.(w.sub.i[.eta.].sub.i,lin
[0156] where w.sub.i is the weight fraction, [.mu.].sub.i are
measured intrinsic viscosities of the long chain branched polymer
fractions, and [.eta.].sub.i,lin are the intrinsic viscosities of
the equivalent linear polymers of the same molecular weight for
each slice, all calculated from the slice data of the GPC/OLV
experiment. The averaging was carried out over the range of
molecular weight for which reliable measures of [.eta.].sub.i could
be made. The data were not corrected for any contribution to g' due
to short chain branching. A molecular weight distribution corrected
for LCB and molecular weight averages corrected for LCB were
calculated in the normal manner. For some analyses of polymers
known not to contain LCB the on-line viscometer was not used and
uncorrected data are reported and hence for these no <g'>LCB
value is given.
[0157] Flow Activation Energy (E) Measurement
[0158] Rheological measurements were carried out on a Rheometrics
RDS-2 with 25 mm diameter parallel plates in the dynamic mode. Two
strain sweep (SS) experiments were initially carried out to
determine the linear viscoelastic strain that would generate a
torque signal which is greater than 10% of the full scale (2000
g-cm) of the transducer over the full frequency (eg 0.01 to 100
rad/s) and temperature (eg 170.degree. to 210.degree. C.) ranges.
The first SS experiment was carried out at the highest test
temperature (eg 210.degree. C.) with a low applied frequency of 0.1
rad/s. This test is used to determine the sensitivity of the torque
at low frequency. The second experiment was carried out at the
lowest test temperature (eg 170.degree. C.) with a high applied
frequency of 100 rad/s. This is to ensure that the selected applied
strain is well within the linear viscoselastic region of the
polymer so that the oscillatory Theological measurements do not
induce structural changes to the polymer during testing. This
procedure was carried out for all the samples.
[0159] The bulk dynamic Theological properties (eg G', G" and
.eta.*) of all the polymers were then measured at 170.degree.,
190.degree. and 210.degree. C. At each temperature, scans were
performed as a function of angular shear frequency (from 100 to
0.01 rad/s) at a constant shear strain appropriately determined by
the above procedure.
[0160] The dynamic Theological data was then analysed using the
Rheometrics RHIOS V4.4 Software. The following conditions were
selected for the time-temperature (t-T) superposition and the
determination of the flow activation energies (Ea) according to an
Arrhenius equation, a.sub.T=exp(E.sub.a/kT), which relates the
shift factor (a.sub.T) to E.sub.a:
1 Rheological Parameters: G'(.omega.), G"(.omega.) &
.eta.*(.omega.) Reference Temperature: 190.degree. C. Shift Mode:
2D (ie horizontal & vertical shifts) Shift Accuracy: High
Interpolation Mode: Spline
[0161] The copolymers of the present invention may also be
described with reference to melt flow ratio which is the ratio of
I.sub.21/I.sub.2 wherein I.sub.21 is measured at 190.degree. C. in
accordance with ASTM-D-1238 Condition E.
[0162] Copolymers according to the invention have a
I.sub.21/I.sub.2 value of .gtoreq.35, preferably .gtoreq.40.
EXAMPLE 1
Preparation and Use of Zr (II) Polymerisation Catalyst
[0163] (i) Treatment of Silica
[0164] A suspension of Crossfield ES70 silica (20 kg, previously
calcined at 500.degree. C. for 5 hours) in 110 litres of hexane was
made up in a 240 litre vessel under nitrogen and 3.0 g of Stadis
425 (diluted in 1 litre hexane) was added. A solution of TEA in
hexane (30.0 moles, 0.940M solution) was added slowly to the
stirred suspension over 30 minutes, while maintaining the
temperature of the suspension at 30.degree. C. The suspension was
stirred for a further 2 hours. The hexane was decanted, and the
silica washed with hexane, so that the aluminium content in the
final washing was less than 1 mmol Al/litre. Finally the suspension
was dried in vacuo at 60.degree. C. to give a free flowing treated
silica powder.
[0165] (ii) Production of Catalyst
[0166] Toluene dried over molecular sieves (350 ml) was added to 10
g of the treated silica powder in a large Schlenk tube in a dry
nitrogen glove box. The tube was shaken well to form a suspension
and left to stand for 1 hour. To the suspension was added a
solution of tris(pentafluorophenyl)- boron in toluene (11.3 ml,
7.85 wt. %, d=0.88 g/ml) by syringe. Then rac ethylene bis indenyl
zirconocene 14 diphenyl butadiene (0.845 g) was added. The
suspension was shaken well for 5 minutes, then dried in vacuo at
ambient temperature to give a free-flowing pink/red powder.
[0167] (iii) Gas-Phase Fluidised Bed Production of an
Ethyene/Hexene-1 Copolymer
[0168] Ethylene, hexene-1, hydrogen and nitrogen were polymerised
using a 15 cm diameter continuous fluidised bed reactor system.
Polymer product was removed at regular intervals from the reactor.
Operating conditions are given in Table 1. The product was a white
free flowing powder.
EXAMPLES 2 AND 3
Preparation and Use of Zr(II) Catalysts
[0169] (i) Treatment of the Silica Support
[0170] 110 litres of hexane was placed in a 240 litre vessel under
nitrogen and 1.7 g of Stadis 425 (diluted at 1 wt. % in hexane) was
added. 11 kg of ES70 Crossfield silica (previously dried at
500.degree. C. for 5 hours) was then added. 16.5 moles of TEA (0.87
mole in hexane) was then added at 30.degree. C. during a period of
30 minutes. After a holding period of 2 hours, the hexane was
decanted and the silica was washed 6 times with 130 litres of
hexane.
[0171] (ii) Production of the Catalyst
[0172] The silica treated as above was dried and then 38 litres of
toluene added. 11.7 kg of rac ethylene bis indenyl zirconocene 1-4
diphenyl butadiene solution in toluene (1.32 wt %) was added at
ambient temperature during a period of 15 minutes. 0.7 g of Stadis
425 (diluted at 1 wt % in toluene) was added The catalyst was then
dried under vacuum (4 mmHg) at 40.degree. C. to give a free flowing
powder.
[0173] Then 2.33 kg of tris pentafluorophenyl boron solution (6.12
wt % in toluene) was added at ambient temperature during a period
of 2 hours while maintaining continuous agitation. After a holding
period of 1 hour again maintaining agitation a pink/red catalyst
having residual solvent therein was obtained.
[0174] (iii) Gas-Phase Fluidised Bed Production of an
Ethylene/Hexene-1 Copolymer
[0175] Ethylene, hexene-1, hydrogen and nitrogen were fed into a 45
cm diameter continuous fluidised bed reactor. Polymer product was
continuously removed from the reactor. Operating conditions are
given in Table 1:
EXAMPLE 4
[0176] (i) Treatment of Silica
[0177] A suspension of ES70 silica (16 kg, previously calcined at
500.degree. C. for 5 hours) in 110 litres of hexane was made up in
a 240 litre vessel under nitrogen. 1.7 g of Stadis 425 diluted in 1
L of hexane was added. A solution of TEA in hexane (24.0 moles,
1.0M solution) was added slowly to the stirred suspension over 30
minutes, while maintaining the temperature of the suspension at
30.degree. C. The suspension was stirred for a further 2 hours. The
hexane was filtered, and the silica washed with hexane, so that the
aluminium content in the final washing was less than 1 mmol
Al/litre. Finally the suspension was dried in vacuo at 60.degree.
C. to give a free flowing treated silica powder.
[0178] (ii) Catalyst Fabrication
[0179] 41.6L of toluene was added to the above treated silica
powder. 12.67 kg of rac ethylene bis indenyl zirconocene 14
diphenyl butadiene solution in toluene (1.16 wt %) was added at
ambient temperature during a period of 15 min then kept at
25.degree. C. for 15 min. 50 ppm of Stadis 425 diluted in 1L of
toluene was added. The catalyst was then dried under vacuum at
40.degree. C. to give a free flowing powder. Then 2.22 Kg of
tris(pentafluorophenyl)boron solution in toluene (6.12 wt %) was
added at ambient temperature during a period of 2 hours while
maintaining continuous agitation After a holding period of 1 h
again maintaining agitation a catalyst having residual solvent
therein was obtained.
[0180] (iii) Gas Phase Fluidised Bed Production of an
Ethylene-Hexene-1 Copolymer
[0181] The polymerisation was carried out as for Example 1, under
conditions summarised in Table 1
EXAMPLE 5
[0182] (i) Treatment of Silica
[0183] 26.24 Kg of TEA treated ES70 silica was prepared in a dryer
under nitrogen essentially as described in Example 4.
[0184] (ii) Catalyst Fabrication
[0185] 10 litres of 0.0809M solution in toluene of bis(hydrogenated
tallow alkyl) methyl ammonium
tris(pentafluorophenyl)(4-hydroxyphenyl)borate, was mixed with 0.9
litres of TEA (1.01M) in toluene. The mixture was added to the
treated silica with agitation and allowed to mix for 45 minutes.
The solvent was removed during 1 hour under vacuum at a temperature
of 31.degree. C. 25 litres of 0.021M rac ethylene bis indenyl
zirconocene 1-4 diphenyl butadiene in toluene was added and allowed
to mix for 45 minutes. The solvent was removed during 105 minutes
under vacuum at 34.degree. C. The finished catalyst was steel-grey
in colour and contained less than 0.25% residual solvent.
[0186] (iii) Gas Phase Fluidised Bed Production of an
Ethylene-Hexene-1 Copolymer
[0187] The polymerisation was carried out as for Examples 2 and 3,
under conditions summarised in Table 1
EXAMPLE 6
[0188] (i) Treatment of Silica Support
[0189] A suspension of ES70 silica (16 kg, previously calcined at
500.degree. C. for 5 hours) in 110 litres of hexane was made up in
a 240 litre vessel under nitrogen. 1.7 g of a solution of Stadis
425 (in 1 litre of hexane) was added. A solution of TEA in hexane
(24.0 moles, 0.838M solution) was added slowly to the stirred
suspension over 30 minutes, while maintaining the temperature of
the suspension at 30.degree. C. The suspension was stirred for a
further 2 hours. The hexane was filtered, and the silica washed
with hexane, so that the aluminium content in the final washing was
less than 0.5 mmol Al/litre. Finally the suspension was dried in
vacuo at 60.degree. C. to give a free flowing treated silica
powder.
[0190] (ii) Production of the Catalyst
[0191] All manipulations were done under an inert nitrogen
atmosphere in a dry box. To 64.5 mL of a 0.073M solution in toluene
of bis(hydrogenated tallow alkyl) methyl ammonium
tris(pentafluorophenyl)(4-hydroxyphenyl)bor- ate, was added 20.8 mL
of 0.25 M Et.sub.3Al in toluene. 84.7 mL of this mixture was
quantitatively added to 150 g of treated silica in a 3 L Round
bottom flask and the resulting mixture was agitated for 30 min at
ambient temperature. The solvent was removed under vacuum at
30.degree. C. to the point where no further evolution of volatiles
was observed. Immediately after, 138.3 mL of 0.017M rac ethylene
bis tetrahydro indenyl zirconocene 1-4 diphenyl butadiene in
toluene were added and the powder was again agitated for 30 min at
ambient temperature. The solvent was removed under vacuum at
ambient temperature to the point where no further evolution of
volatiles was observed.
[0192] (iii) Gas Phase Fluidised Bed Production of an
Ethylene-Hexene-1 Copolymer
[0193] The polymerisation was carried out as for Example 1, under
conditions summarised in Table 1
EXAMPLE 7
[0194] All manipulations were done under an inert nitrogen
atmosphere in a dry box.
[0195] (i) Treatment of Silica
[0196] Twenty grams of Crosfield ES-70 silica that were calcined in
air at 500.degree. C. were accurately weighed into a 250 mL Schlenk
flask. 125 mL of hexane were added to make a slurry. 30.8 mL of 1.0
M TEA in hexane were added while swirling the flask by hand and the
flask was left to stand for 1 hour. The treated silica was filtered
on a flit and washed with several volumes of hexane. The silica was
dried to constant weight under vacuum at ambient temperature. 21.7
g of treated silica were recovered
[0197] (ii) Production of Catalyst
[0198] Two grams of the above treated silica were accurately
weighed into a 100 mL Schlenk flask and 8 cc of toluene were added
to make a slurry. 2.4 mL of 0.017 M rac ethylene bis tetrahydro
indenyl zirconocene 1-4 diphenyl butadiene in toluene and 0.5 mL of
0.127 M tris(pentafluorophenyl)boron were added, in that order,
while swirling the flask by hand. The solvent was-removed till
constant weight, under vacuum at ambient temperature. 1.9 g of
catalyst powder were recovered.
[0199] (iii) Gas Phase Production of an Ethylene-Hexene-1
Copolymer
[0200] The polymerisation was carried out in a 2.5-litre stirred,
fixed bed autoclave. This was charged with 300 g dry NaCl, and
stirring was begun at 300 rpm. The reactor was pressurised to 8.39
bar ethylene that contained 500 ppm volume of hydrogen and heated
to 71.degree. C. 1-hexene was introduced to a level of 6000 ppm
volume as measured on a mass spectrometer. 0.5 g of TEA was
introduced into the reactor. In a separate vessel, 0.1 g catalyst
was mixed with an additional 0.5 g TEA treated silica. The combined
catalyst and TEA treated silica were subsequently injected into the
reactor. Ethylene pressure was maintained on a feed as demand, and
hexene was fed as a liquid to the reactor to maintain the ppm
concentration. Temperature was regulated by dual heating and
cooling baths. After 180 minutes the reactor was depressurised, and
the salt and polymer were removed via a dump valve. The polymer was
washed with copious distilled water to remove the salt, then dried
at 50.degree. C. 282 g of a white polymer powder was recovered.
2 TABLE 1 Example 1 Example 2 Example 3 Example 4 Example 5 Example
6 Total pressure (bar) 14.3 19 19 14.3 18 14.5 Temperature
(.degree. C.) 70 70 70 70 65 70 C2 pressure (bar) 12 11.8 10 8 8.5
4 H2/C2 0.0005 0.0005 0.0014 0.0003 0.00056 0.0006 C6/C2 0.007
0.0061 0.0055 0.007 0.0057 0.0075 Production(Kg/h) 1.3 43 39 1 100
0.7
[0201]
3 TABLE 2 Property MFR (2.16 kg) Density (.ANG.) Ea h(500/s) MS
(500/s) P (500/s) d(MS)/d(log .delta.) d(MS/d(P) Polymers (g/10
min) (kg/m{circumflex over ( )}3) Mw/Mn <g>LCB (kl/mol) (Pa
.multidot. s) (cN) (MPa) (cN) (cN/MPa) Example 1 1.1 920 5.9 0.68
65.1 260 16.7 15.6 9.22 0.81 Example 2 0.3 920 5.0 0.74 74.1 290
19.3 17.5 8.62 0.85 Example 3 1.0 923 5.3 0.77 67.0 220 16.2 14.4
9.19 0.85 Example 4 0.9 920.3 5.3 0.80 65.4 240 17.7 14.7 11.10
1.04 Example 5 1.1 917.9 3.6 -- 62.4 385 10.0 17.8 5.81 0.50
Example 6 1.3 921.4 3.5 -- 56.7 400 6.3 18.6 4.03 0.37 Example 7
0.66 926.8 3.7 -- 66.7 455 5.0 13.7 3.13 0.33 Exceed MLL27MAX 0.85
926 2.3 1.0 -- 690 4.4 32.0 2.11 0.13 Exceed 350D60 1.12 917.7 2.1
-- 30.8 760 4.0 31.0 1.77 0.11 Dowlex 2045 1.1 919 3.3 -- 32.0 580
5.5 23.0 2.00 0.15 MOBIL NTA 101 0.84 920 3.4 -- 31.0 515 4.8 25.0
2.15 0.16 LL7209AA 0.9 920 3.8 -- 31.3 570 6.3 24.4 2.85 0.22
LL7206AF 0.6 920 3.9 -- 31.0 600 9.5 27.0 4.19 0.33 Borealis LE6592
0.15 922.9 11.5 -- -- 370 15.0 20.0 6.25 0.70 Affinity FM 1570 1.0
915 2.2 0.92 60.8 570 5.5 24.0 2.64 0.19 EBI/Zr(IV)/MAO 0.77 918.3
3.4 0.85 60.2 440 13.0 19.5 7.38 0.59 LD5320AA 2.1 921 6.8 0.59
57.8 240 14.5 12.8 11.88 1.05 LD5310AA 1.0 923 7.0 0.53 65.3 300
16.6 14.0 8.67 1.07
[0202] Film Tests
[0203] Film was produced from the product of example 2 and LD5310AA
using a Collin single screw film extruder (45 mm, 25L/D) equipped
with an LDPE screw and using a temperature profile typical of that
used for extrusion of LDPE. The results are summarised in Table 3
together with results for examples 8-10 which were produced under
similar catalyst and polymerisation conditions to example 2.
[0204] It can be seen that for all of the example polymers that the
extrusion behaviour is improved compared to the control LDPE
product as judged by their lower extrusion head pressure, lower
motor load and lower specific energy. In addition, this has been
achieved for products with melt indices lower than the conventional
LDPE ie products which might be expected to show more difficult
extrusion behaviour. At the same time, mechanical properties
similar to LDPE or improved have been obtained.
[0205] Similar film extrusions have been carried out for examples 5
and 6 and these are reported in Table 4. For these products, the
processing is less advantageous compared to LDPE, as evidenced by
the values for head pressure, motor load and specific energy, but
the mechanical are considerably better than LDPE and the optical
properties are comparable.
[0206] Film Test Methods
[0207] Film dart impact was measured according to ASTM D1709,
(Method A) teas strength by ASTM D1922, and tensile properties by
ASTM D822. Haze was measured by ASTM D1003 and gloss by D2457.
4TABLE 3 Example 2 8 9 10 LD5310AA Compounding Machine ZSK53 ZSK58
ZSK58 ZSK58 CaSt ppm 1250 1250 1250 1250 Irganox 1076 ppm 500 500
500 500 Irgafos PEPQ ppm 800 800 800 800 Pellet properties Melt
Index g/10 min 0.31 0.32 1.38 0.68 0.9 Density Kg/m3 920 922.9 922
919.5 921 121/12 95 84 51 69 62 Film extrusion Machine Collin
Collin Collin Collin Collin Die mm 100 100 100 100 100 Die gap mm
0.8 0.8 0.8 0.8 0.8 T.degree. Profil 175/190/ 140/150/ 140/150/
140/150/ 140/150/ 195/200/ 160/170/ 160/170/ 160/170/ 160/170/
200/200/ 170/170/ 170/170/ 170/170/ 170/170/ 210/210 190/180
190/180 190/180 190/180 Screw speed rpm 40 40 41 40 45 Melt
pressure bal 151 238 166 187 245 Output Kg/h 12 12 12 12 12 Motor
Load A 10.7 14.5 11.7 13.9 13.6 Melt Temp. .degree. C. 190 165 161
162 163 Haul off rate m/mn 10.2 8.8 11 9.1 10 BUR 2:1 2:1 2:1 2:1
2:1 Frostline mm 250 160 120 350 120 Specific energy Kwh/Kg 0.12
0.17 0.14 0.16 0.18 Film properties Thickness um 38 38 38 39-41 38
Dart impact g 160 205 103 170 140 MD tens. st. MPa 23.5 36 break TD
tens. st. MPa 24 25 break MD elongation % 520 350 TD elongation %
650 710
[0208]
5TABLE 4 Example LD5310AA 5 6 Compounding Machine ZSK58 ZSK53 CaSt
ppm 1250 1250 Irganox 1076 ppm 500 500 Irgefos PEPQ ppm 800 800
Pellet properties Malt Index g/10 min 0.85 0.52 1.29 Density Kg/m3
921 918.3 921.4 121/12 61 65.4 40 Film extrusion Machine Collin
Collin Collin Die mm 100 100 100 Die gap mm 0.8 0.8 0.8 T.degree.
Profil 140/150/160/ 140/150/160/ 140/150/160/ 170/170/170/
170/170/170/ 170/170/170/ 190/180 190/180 190/180 Screw speed rpm
44 42 42 Melt pressure bal 224 273 297 Output Kg/h 12 12 12 Motor
Load A 15.3 16.7 17.2 Melt Temp. .degree. C. 155 153 157 Haul off
rate m/mn 9.6 9.6 9.3 BUR 2:1 2:1 2:1 Frostline mm 350 350 350
Specific energy kWh/Kg 0.19 0.20 0.21 Film properties Thickness um
38 38 38 Dart impact g 102 360 252 Haze % 5 10.7 8.1 Gloss o/oo 72
50 61
* * * * *