U.S. patent application number 16/573250 was filed with the patent office on 2020-01-30 for ethylene-based polymer compositions for improved extrusion coatings.
The applicant listed for this patent is Dow Global Technologies LLC. Invention is credited to James L. Cooper, Mehmet Demirors, Teresa P. Karjala, Yijian Lin.
Application Number | 20200032039 16/573250 |
Document ID | / |
Family ID | 53762316 |
Filed Date | 2020-01-30 |
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United States Patent
Application |
20200032039 |
Kind Code |
A1 |
Demirors; Mehmet ; et
al. |
January 30, 2020 |
ETHYLENE-BASED POLYMER COMPOSITIONS FOR IMPROVED EXTRUSION
COATINGS
Abstract
The invention provides a composition comprising at least the
following: a) a first composition comprising at least one first
ethylene-based polymer, formed by high pressure, free-radical
polymerization, and wherein the first composition comprises the
following properties: a melt index (I2) from 1.0 to 15.0 g/10 min,
and density from 0.910 to 0.940 g/cc; b) a second composition
comprising at least one second ethylene-based polymer, and wherein
the second composition comprises the following properties; a melt
index (I2) from 1.0 to 1000 g/10 min, a density greater than 0.940
g/cc; wherein the composition comprises the following properties:
melt index (I2) from 2.0 to 20.0 g/10 min, and a density from 0.915
to 0.940 g/cc; and wherein the first composition is present in an
amount from 65 to 95 wt %, based on the weight of the
composition.
Inventors: |
Demirors; Mehmet; (Pearland,
TX) ; Karjala; Teresa P.; (Lake Jackson, TX) ;
Lin; Yijian; (Manvel, TX) ; Cooper; James L.;
(Brazoria, TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Dow Global Technologies LLC |
Midland |
MI |
US |
|
|
Family ID: |
53762316 |
Appl. No.: |
16/573250 |
Filed: |
September 17, 2019 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
|
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15574261 |
Nov 15, 2017 |
10457799 |
|
|
PCT/US2015/038626 |
Jun 30, 2015 |
|
|
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16573250 |
|
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08L 23/06 20130101;
C08L 2207/062 20130101; C08L 2205/025 20130101; C09D 123/06
20130101; C08L 2207/066 20130101; C08L 23/06 20130101; C08L 23/06
20130101; C08L 23/06 20130101; C08L 23/0815 20130101; C09D 123/06
20130101; C08L 23/06 20130101; C09D 123/06 20130101; C08L 23/0815
20130101 |
International
Class: |
C08L 23/06 20060101
C08L023/06; C09D 123/06 20060101 C09D123/06 |
Claims
1. A composition comprising at least the following: a) a first
composition comprising at least one first ethylene-based polymer,
formed by high pressure, free-radical polymerization, and wherein
the first composition comprises the following properties: a melt
index (I2) from 1.0 to 15.0 g/10 min, and density from 0.910 to
0.940 g/cc; b) a second composition comprising at least one second
ethylene-based polymer, and wherein the second composition
comprises the following properties: a melt index (I2) from 1.0 to
1000 g/10 min, and a density greater than 0.940 g/cc; wherein the
melt index (I2) ratio of the melt index (I2) of the second
composition to the melt index (I2) of the first composition is from
0.50 to 2.70; wherein the composition comprises the following
properties: melt index (I2) from 2.0 to 20.0 g/10 min, and a
density from 0.910 to 0.935 g/cc; and wherein the first composition
is present in an amount from 65 to 95 wt %, based on the weight of
the composition.
2. The composition of claim 1, wherein the melt index (I2) ratio of
"the composition" to "the second composition" is from 0.30 to
2.00.
3. The composition of claim 1, wherein the first ethylene-based
polymer is prepared in a tubular reactor.
4. The composition of claim 1, wherein the first composition
comprises .gtoreq.95 wt % of the first ethylene-based polymer,
based on the weight of the first composition.
5. The composition of claim 1, wherein the first ethylene-based
polymer is a low density polyethylene (LDPE).
6. The composition of claim 1, wherein the second composition
comprises .gtoreq.95 wt % of the second ethylene-based polymer,
based on the weight of the second composition.
7. The composition of claim 1, wherein the second composition has a
density from 0.940 to 0.966 g/cc.
8. The composition of claim 1, wherein the second ethylene-based
polymer is a high density polyethylene (HDPE).
9. The composition of claim 1, wherein the melt index (I2) ratio of
the composition to the first composition is from 0.50 to 3.00.
10. The composition of claim 1, wherein the first composition has a
melt index (I2) from 3.0 to 10.0 g/10 min.
11. The composition of claim 1, wherein the first composition is
present in an amount from 75 to 95 wt %, based on the weight of the
composition.
12. The composition of claim 1, wherein the second composition has
a melt index (I2) from 4.0 to 40.0 g/10 min.
13. The composition of claim 1, wherein the composition has a
density from 0.910 to 0.930 g/cc.
14. The composition of claim 1, wherein the first composition, is
prepared in a tubular reactor, and has a melt index (I2) from 3.0
to 10.0 g/10 min, and a G' value (at G''=500 Pa, 170.degree.
C.).gtoreq.127.5 Pa-1.25 Pa/(g/10 min).times.I2.
15. The composition of claim 1, wherein the first composition is
prepared in a tubular reactor, and has a melt index (I2) from 3.0
to 10.0 g/10 min, a density from 0.916 to 0.928 g/cc; the second
composition has a melt index (I2) from 4.0 to 20.0 g/10 min, a
density from 0.955 to 0.970 g/cc; and wherein the composition has a
melt index (I2) from 3.0 to 10.0 g/10 min, and a G'(at G''=500 Pa,
170.degree. C.) from 100 to 200 Pa; and wherein the second
composition is present in an amount from 10 to 20 wt %, based on
the weight of the composition.
16. The composition of claim 1, wherein a coating the composition
has a Water Vapor Transmission Rate, WVTR (38.degree. C. 100% RH
according to ASTM1249-06, 1 mil coating).ltoreq.1.8 (g/100
in.sup.2/day).
17. An article comprising at least one component formed from the
composition of claim 1.
18. The article of claim 17, wherein the article is a coating, a
film, a foam, a laminate, a fiber, or a tape.
Description
CROSS-REFERENCE TO RELATED APPLICATIONS
[0001] The present application is a continuation application of and
claims priority to U.S. patent application Ser. No. 15/574,261,
filed on Nov. 15, 2017, entitled "ETHYLENE-BASED POLYMER
COMPOSITIONS FOR IMPROVED EXTRUSION COATINGS," which is a national
stage entry of International Application PCT/US2015/038626, filed
on Jun. 30, 2015, entitled "ETHYLENE-BASED POLYMER COMPOSITIONS FOR
IMPROVED EXTRUSION COATINGS," all of which are incorporated by
reference herein in their entirety.
BACKGROUND
[0002] The invention is directed to ethylene-based polymer
compositions that have improved extrusion coating, adhesion, and
barrier properties. Polymer compositions based on LDPE are often
used in extrusion coating applications. LDPE prepared using tubular
technology ("tubular LDPE") is more economical than LDPE prepared
using autoclave technology ("autoclave LDPE"). However, "tubular
LDPE" has lower melt strength, which often can lead to poorer
extrusion coating properties. Thus, there is a need for new polymer
compositions based on more economical "tubular LDPE," and which
have improved extrusion coating properties. There is a further need
for such compositions that have improved adhesion and barrier
properties.
[0003] International Publication WO 2014/081458 discloses
compositions comprising a first ethylene-based polymer, formed by a
high pressure, free-radical polymerization process, and comprising
the following properties: a) a Mw(abs) versus melt index I2
relationship: Mw(abs)<A.times.[(I2)B], where
A=5.00.times.10.sup.2 (kg/mole)/(dg/min)B, and B=-0.40; and b) a MS
versus I2 relationship: MS.gtoreq.C.times.[(I2)D], where C=13.5
cN/(dg/min)D, and D=-0.55. These compositions can be used to form
coatings, film, foam, laminate, fibers, tapes, wire and cable, and
woven or non-woven fabrics.
[0004] B. H. Gregory, Extrusion Coating, A Process Manual, 2010,
page 141, discloses HDPE/LDPE blends for extrusion coating.
International Publication WO 2005/068548 discloses a polymer
composition for extrusion coating with good process properties
comprising a multimodal high density polyethylene and a low density
polyethylene.
[0005] International Publication WO 2013/078018 discloses
compositions comprising an ethylene-based polymer comprising the
following properties: a) a melt index (I2)>2.0 dg/min; b) a
Mw(abs) versus I2 relationship: Mw(abs)<A+B(I2), where
A=2.40.times.10.sup.5 kg/mole, and B=-8.00.times.10.sup.3
(g/mole)/(dg/min); and c) a G' versus I2 relationship:
G'>C+D(I2), where C=127.5 Pa, and D=-1.25 Pa/(dg/min). The
invention also provides an ethylene-based polymer comprising the
following properties: a) a melt index (I2)>2.0 dg/min; b) a G'
versus I2 relationship: G'>C+D(I2), where C=127.5 Pa, and
D=-1.25 Pa/(dg/min) c) a chloroform extractable (Clext) versus G'
relationship: Clext.<E+FG', where E=0.20 wt %, and F=0.060 wt
%/Pa; and d) a "weight fraction (w) of molecular weight greater
than 10.sup.6 g/mole, based on the total weight of polymer, and as
determined by GPC(abs)," that meets the following relationship:
w<I+J(I2), where I=0.080, and J=-4.00.times.10.sup.-3 min/dg.
The compositions can be used for extrusion coating
applications.
[0006] U.S. Pat. No. 7,956,129 discloses polymer blends comprising
(a) 1-99% by weight of a copolymer of ethylene and an alpha olefin
having from 3 to 10 carbon atoms, said copolymer having (iv) a
density in the range 0.905 to 0.940 gcm.sup.3, (v) a melt elastic
modulus G' (G''=500 Pa) in the range 10 to 150 Pa, and (vi) a melt
index in the range 5 to 50, and (b) from 1-99% by weight of a low
density polyethylene (LDPE) polymer having a density from 0.914 to
0.928 gcm.sup.-3, wherein the sum of (a) and (b) is 100%. The
copolymers of component (a) are typically prepared by use of
metallocene catalysts. The blends exhibit advantageous melt elastic
modulus in the range 30 to 200 Pa. The blends are disclosed as
suitable for extrusion coating applications.
[0007] International Publication WO 2014/081458 discloses an
extrusion coating process of a polyethylene resin on a substrate,
and where the polyethylene resin has a density from 0.940
g/cm.sup.3 to 0.960 g/cm.sup.3, and is prepared in the presence of
an activated bridged bis-(tetrahydro-indenyl) metallocene catalyst.
The resin may be used alone or in combination with LDPE.
[0008] U.S. Pat. No. 7,812,094 discloses a polymer blend suitable
for the production of film, said polymer blend comprising at least
(1) a multimodal high density polyethylene (HDPE) composition, and
(2) a low density polyethylene (LDPE) polymer, a linear low density
polyethylene (LLDPE) polymer or a mixture of LDPE and LLDPE
polymers. The HDPE composition comprising a multimodal HDPE
polymer, which contains at least a lower molecular weight (LMW)
polyethylene component and a higher molecular weight (HMW)
polyethylene component.
[0009] Other ethylene-based polymer compositions for coatings
and/or other applications are disclosed in the following
references: U.S. Pat. Nos. 8,247,065, 6,291,590, 7,776,987;
International Publications Nos. WO83/00490, WO2015/092662, WO
2014/190041, WO 2014/190036, WO 2014/190039, WO2013178242A1,
WO2013178241A1, WO 2013/078224; European Patent Application Nos.
1187876A1, EP0792318A1, EP1777238A1, EP2123707A1, and EP2123707A1.
See also, A. Ghijsels et al., Melt Strength Behavior of
Polyethylene Blends, Intern. Polymer Processing, VII, 1992, pp.
44-50; M. Xanthos et al., Measurement of Melt Viscoelastic
Properties of Polyethylenes and Their Blends--A Comparison of
Experimental Techniques, Polymer Engineering and Science, Vol. 37,
No. 6, 1997, pp. 1102-1112; INEOS, Olefins and Polymers Europe,
Your Partner in Extrusion Coating, Goods that Make Our Life
Convenient, prior to May 2015, six pages; K. R. Frey, Polyethylene
and Polypropylene in Flexible Barrier Packaging, 2009 Consumer
Packaging Solutions for Barrier Performance course, TAPPI Place, 45
pages; N. Savargaonkar et al., Formulating LLDPE/LDPE Blends for
Abuse--Resistant Blown Film, Plastics Technology, 2014, pp. 44-47
and 50.
[0010] However, as discussed above, there is a need for new polymer
compositions, based on more economical "tubular LDPE," and which
have improved extrusion coating properties. There is a further need
for such compositions that have improved adhesion (for example,
Heat Seal Strength) and barrier (for example, Water Vapor
Transmission Rate) properties. These needs have been met by the
following invention.
SUMMARY OF INVENTION
[0011] The invention provides a composition comprising at least the
following:
[0012] a) a first composition comprising at least one first
ethylene-based polymer, formed by high pressure, free-radical
polymerization, and wherein the first composition comprises the
following properties: a melt index (I2) from 1.0 to 15.0 g/10 min,
and density from 0.910 to 0.940 g/cc;
[0013] b) a second composition comprising at least one second
ethylene-based polymer, and wherein the second composition
comprises the following properties; a melt index (I2) from 1.0 to
1000 g/10 min, a density greater than 0.940 g/cc;
[0014] wherein the composition comprises the following properties:
melt index (I2) from 2.0 to 20.0 g/10 min, and a density from 0.915
to 0.940 g/cc; and
[0015] wherein the first composition is present in an amount from
65 to 95 wt %, based on the weight of composition.
BRIEF DESCRIPTION OF THE DRAWINGS
[0016] FIG. 1 depicts a polymerization configuration. As seen in
FIG. 1, the notations are as follows: fresh ethylene is fed through
line 1; discharge of Primary A is sent through line 2; discharge of
Primary B is sent through line 3; 4 and 5 are each a line feed to
the Hyper compressor; fresh CTA is fed through each of lines 6 and
7; 8 is a line feed to feed lines 20 and 21, each to the side of
the reactor; 9 is a line feed from the Hyper compressor to the
front of the reactor; 10 is a line feed from the reactor to the HPS
(High Pressure Separator); 11 is a line feed from the HPS to the
LPS (Low Pressure Separator); 12 is a discharge line from the LPS;
13 is a line feed from the LPS to the Booster; 14 is a discharge
feed from the Booster; 15 is a recycle feed line from the HPS to
lines 16 and 17; 16 is a purge line; 17 is a recycle line; 18 and
19 are recycle lines to the Hyper compressor.
[0017] FIG. 2 depicts DSC thermograms of several LDPE/HDPE
compositions (first cooling).
[0018] FIG. 3 depicts DSC thermograms of several LDPE/HDPE
compositions (second heating).
[0019] FIG. 4 depicts DSC thermograms of some LDPE polymers (first
cooling).
[0020] FIG. 5 depicts DSC thermograms of some LDPE polymers (second
heating).
[0021] FIG. 6 depicts the test sample configuration in the MTS
Universal Tensile Testing Machine for the Heat Seal Study.
DETAILED DESCRIPTION
[0022] As discussed above, the invention provides a composition
comprising the following:
[0023] a) a first composition comprising at least one first
ethylene-based polymer, formed by high pressure, free-radical
polymerization, and wherein the first composition comprises the
following properties: a melt index (I2) from 1.0 to 15.0 g/10 min,
and density from 0.910 to 0.940 g/cc;
[0024] b) a second composition comprising at least one second
ethylene-based polymer, and wherein the second composition
comprises the following properties; a melt index (I2) from 1.0 to
1000 g/10 min, a density greater than 0.940 g/cc;
[0025] wherein the composition comprises the following properties:
melt index (I2) from 2.0 to 20.0 g/10 min, and a density from 0.915
to 0.940 g/cc; and
[0026] wherein the first composition is present in an amount from
65 to 95 wt %, based on the weight of composition.
[0027] The inventive composition may comprise a combination of two
or more embodiments described herein.
[0028] The first composition may comprise a combination of two or
more embodiments described herein.
[0029] The first ethylene-based polymer may comprise a combination
of two or more embodiments as described herein.
[0030] The second composition may comprise a combination of two or
more embodiments described herein.
[0031] The second ethylene-based polymer may comprise a combination
of two or more embodiments as described herein.
[0032] In one embodiment, the melt index (I2) ratio of "the second
composition" to "the first composition" is from 0.50 to 2.70, or
from 0.5 to 2.65, or from 0.5 to 2.60, or from 0.5 to 2.50.
[0033] In one embodiment, the melt index (I2) ratio of "the
composition" to "the second composition" is from 0.30 to 2.00, or
from 0.40 to 2.00, or from 0.50 to 2.00.
[0034] In one embodiment, the first composition has a melt index
(I2) from 1.0 g/10 min to 10.0 g/10 min, further from 2.0 g/10 min
to 10.0 g/10 min, further from 3.0 to 10.0 g/10 min, further from
3.0 g/10 min to 6.0 g/10 min (ASTM 2.16 kg/190.degree. C.).
[0035] In one embodiment, the first composition has a density
greater than, or equal to, 0.915 g/cc, or greater than, or equal
to, 0.918 g/cc.
[0036] In one embodiment, the first composition has a density
greater than, or equal to, 0.920 g/cc, or greater than, or equal
to, 0.922 g.
[0037] In one embodiment, the first composition has a density less
than, or equal to, 0.940 g/cc, further less than, or equal to,
0.935 g/cc, further less than, or equal to, 0.935 g/cc.
[0038] In one embodiment, the first composition has a density from
0.910 to 0.940 g/cc, further from 0.915 g/cc to 0.930 g/cc (1 cc=1
cm.sup.3).
[0039] In one embodiment, the first composition is polymerized in a
tubular reactor.
[0040] In one embodiment, the first composition polymer is
polymerized in at least one tubular reactor. In a further
embodiment, the first composition is polymerized in a tubular
reactor system that does not comprise an autoclave reactor.
[0041] In one embodiment, the first composition is prepared in a
reactor configuration comprising at least one tubular reactor.
[0042] The first composition may comprise a combination of two or
more embodiments as described herein.
[0043] In one embodiment, the first composition is present in an
amount from 70 to 95 wt %, further from 75 to 95 wt %, further from
80 to 95 wt %, further from 80 to 90 wt %, based on the weight of
the composition.
[0044] In one embodiment, the first composition comprises
.gtoreq.95 wt %, further .gtoreq.98 wt %, further .gtoreq.99 wt %
of the first ethylene-based polymer, based on the weight of the
first composition. In a further embodiment, the first
ethylene-based polymer is a LDPE.
[0045] In one embodiment, the first ethylene-based polymer has a
melt index (I2) from 1.0 g/10 min to 10.0 g/10 min, further from
2.0 g/10 min to 10.0 g/10 min, further from 2.5 g/10 min to 6.0
g/10 min (ASTM 2.16 kg/190.degree. C.).
[0046] In one embodiment, the first ethylene-based polymer has a
density greater than, or equal to, 0.915 g/cc, or greater than, or
equal to, 0.918 g/cc.
[0047] In one embodiment, the first ethylene-based polymer has a
density greater than, or equal to, 0.920 g/cc, or greater than, or
equal to, 0.922 g.
[0048] In one embodiment, the first ethylene-based polymer has a
density less than, or equal to, 0.940 g/cc, further less than, or
equal to, 0.935 g/cc, further less than, or equal to, 0.930
g/cc.
[0049] In one embodiment, the first ethylene-based polymer has a
density from 0.910 to 0.940 g/cc, further from 0.915 g/cc to 0.930
g/cc (1 cc=1 cm.sup.3).
[0050] In one embodiment, the first composition is prepared in a
tubular reactor, and has a melt index (I2) from 3.0 to 10.0 g/10
min, and a G' value (at G''=500 Pa, 170.degree. C.).gtoreq.127.5
Pa-1.25 Pa/(g/10 min).times.I2.
[0051] In one embodiment, the first composition is prepared in a
tubular reactor, and has a melt index (I2) from 3.0 to 10.0 g/10
min, a density from 0.916 to 0.928 g/cc, further 0.916 to 0.925
g/cc, further from 0.916 to 0.920 g/cc; the second composition has
a melt index (I2) from 4.0 to 20.0 g/10 min, a density from 0.955
to 0.970 g/cc; and wherein the composition has a melt index (I2)
from 3.0 to 10.0 g/10 min, and a G'(at G''=500 Pa, 170.degree. C.)
from 100 to 200 Pa; and wherein the second composition is present
in an amount from 10 to 20 wt %, based on the weight of the
composition.
[0052] In one embodiment, the first ethylene-based polymer is
selected from a polyethylene homopolymer or an ethylene-based
interpolymer.
[0053] In one embodiment, the first ethylene-based polymer is a
LDPE.
[0054] In one embodiment, the first ethylene-based polymer is
polymerized in at least one tubular reactor. In a further
embodiment, the first ethylene-based polymer is polymerized in a
tubular reactor system that does not comprise an autoclave
reactor.
[0055] In one embodiment, the first ethylene-based polymer is
prepared in a tubular reactor.
[0056] In one embodiment, the first ethylene-based polymer is
prepared in a reactor configuration comprising at least one tubular
reactor.
[0057] The first ethylene-based polymer may comprise a combination
of two or more embodiments as described herein.
[0058] In one embodiment, the first ethylene-based polymer is
present in an amount from 70 to 95 wt %, further from 75 to 95 wt
%, further from 80 to 95 wt %, further from 80 to 90 wt %, based on
the weight of the composition.
[0059] In one embodiment, the composition has a melt index (I2)
from 2.0 to 15.0 g/10 min, further from 2.5 to 10.0 g/10 min, and
further from 3.0 to 5.0 g/10 min, and further from 3.0 to 4.0 g/10
min.
[0060] In one embodiment, the composition has a density from 0.910
to 0.935 g/cc, further from 0.910 to 0.930 g/cc.
[0061] In one embodiment, the melt index (I2) ratio of the
composition to the first ethylene-based polymer is from 0.50 to
3.00, or from 0.55 to 2.95, or from 0.60 to 2.90, or from 0.65 to
2.85.
[0062] In one embodiment, the composition has a G' value at a
G''=500 Pa greater than, or equal to, 80 Pa, at 170.degree. C.,
further greater than, or equal to, 90 Pa, at 170.degree. C.,
further greater than, or equal to, 100 Pa, at 170.degree. C.
[0063] In one embodiment, the composition has a G' value at G''=500
Pa, greater than, or equal to, 120 Pa, at 170.degree. C., further
greater than, or equal to, 130 Pa, at 170.degree. C., further
greater than, or equal to, 140 Pa, at 170.degree. C.
[0064] In one embodiment, the composition has a Water Vapor
Transmission Rate value as follows: WVTR (38.degree. C. 100% RH
according to ASTM 1249-06, at 1 mil thickness coating).ltoreq.1.8
(g/100 in.sup.2/day), further .ltoreq.1.7 (g/100 in.sup.2/day),
further .ltoreq.1.6 (g/100 in.sup.2/day).
[0065] In one embodiment, the composition of any one of the
previous claims, wherein the first composition is prepared in a
tubular reactor, and has a melt index (I2) from 3.0 to 10.0 g/10
min, further from 3.0 to 5.0 g/10 min, a density from 0.916 to
0.928 g/cc; the second composition has a melt index (I2) from 4.0
to 20.0 g/10 min, a density from 0.955 to 0.970 g/cc; and wherein
the composition has a melt index (I2) from 3.0 to 10.0 g/10 min,
and a G' (at G''=500 Pa, 170.degree. C.) from 100 to 200 Pa; and
wherein the second composition is present in an amount from 10 to
20 wt %, based on the weight of the composition.
[0066] In one embodiment, the composition has a melt strength
greater than, or equal to, 9.0 cN, at 190.degree. C., further
greater than, or equal to, 12.0 cN, at 190.degree. C., further
greater than, or equal to, 15.0 cN, at 190.degree. C.
[0067] In one embodiment, the composition has a melt strength value
greater than, or equal to, 8.0 cN, at 190.degree. C., further
greater than, or equal to, 9.0 cN, at 190.degree. C., further
greater than, or equal to, 10.0 cN, at 190.degree. C.
[0068] In one embodiment, the composition has a "neck-in" value
.ltoreq.3 inch, at a set polymer melt temperature=600.degree. F., a
coating thickness=1 mil, an open die width=24 inches, a die gap=25
mils, an air gap=6 inches, a throughput rate=250 pounds/hour and a
line speed=440 feet/min.
[0069] In one embodiment, the composition has a "draw-down" value
.gtoreq.800 feet/min, at a set polymer melt temperature=600.degree.
F., a coating thickness=1 mil, an open die width=24 inches, a die
gap=25 mils, an air gap=6 inches, and a throughput rate=250
pounds/hour. Draw down is defined as the maximum line speed
attainable before web breakage or web defects/edge inconsistencies
occur, when accelerating the line speed at a constant polymer
output. The constant polymer coating output level is set by a
throughput rate of 250 pounds/hour. Neck-in is the difference
between the final width of the web and the die width at fixed line
speed.
[0070] In one embodiment, the composition comprises .gtoreq.95 wt
%, further .gtoreq.98 wt %, further .gtoreq.99 wt % the sum of
components a and b, based on the weight of the composition.
[0071] In one embodiment, the composition has at least one melting
temperature (Tm).gtoreq.110.degree. C., or .gtoreq.115.degree. C.,
or .gtoreq.120.degree. C.
[0072] In one embodiment, the composition has at least one melting
temperature (Tm) from 95.degree. C. to 115.degree. C., or from
97.degree. C. to 112.degree. C., or from 100.degree. C. to
110.degree. C.
[0073] In one embodiment, the composition has a tan delta (0.1
rad/s, 190.degree. C.).gtoreq.3.00, or .gtoreq.3.50, or
.gtoreq.4.00.
[0074] In one embodiment, the composition has a tan delta (0.1
rad/s, 190.degree. C.) from 3.00 to 10.00, or from 3.50 to 9.00, or
from 4.00 to 8.00.
[0075] In one embodiment, the composition has a V0.1/V100 (each at
190 C).gtoreq.6.0, or .gtoreq.7.0, or .gtoreq.8.0.
[0076] In one embodiment, the composition has a V0.1/V100 (each at
190.degree. C.) from 6.0 to 14.0, or from 7.0 to 12.0, or from 8.0
to 10.0.
[0077] In one embodiment, the composition has a V0.1 (0.1 rad/s,
190.degree. C.).gtoreq.1900 Pas, or .gtoreq.2000 Pas, or
.gtoreq.2500 Pas.
[0078] In one embodiment, the composition has a V0.1 (0.1 rad/s,
190.degree. C.) from 1900 to 5000 Pas, or from 2000 to 5000 Pas, or
from 2500 to 5000 Pas, or from 3000 Pas to 5000 Pas.
[0079] In one embodiment, the composition has a
M.sub.w,cc.gtoreq.350,000 g/mole, or .gtoreq.400,000 g/mole, or
.gtoreq.450,000 g/mole.
[0080] In one embodiment, the composition has M.sub.w,cc from
350,000 to 900,000 g/mole, or from 400,000 g/mole to 850,000
g/mole, or from 450,000 to 800,000 g/mole.
[0081] In one embodiment, the composition has a
M.sub.w,cc/M.sub.n,cc.gtoreq.7.00, or .gtoreq.7.50, or
.gtoreq.8.00.
[0082] In one embodiment, the composition has a
M.sub.w,abs/M.sub.n,cc from 7.00 to 12.00, or from 7.00 to 11.00,
or from 7.00 to 10.00.
[0083] In one embodiment, the composition has a
M.sub.w,abs/M.sub.n,cc.gtoreq.16.0, or .gtoreq.17.0, or
.gtoreq.18.0.
[0084] In one embodiment, the composition has an
M.sub.w,abs/M.sub.n,cc from 16.0 to 26.0, or from 17.0 to 25.0, or
from 18.0 to 24.0.
[0085] In one embodiment, the composition is prepared by a melt
compounding process, or by a dry blending process.
[0086] An inventive composition may comprise a combination of two
or more embodiments as described herein.
[0087] In one embodiment, the second composition has a density
>0.945, or .gtoreq.0.950, or .gtoreq.0.955, or .gtoreq.0.960
g/cc.
[0088] In one embodiment, the second composition has a melt index
(I2) from 4.0 to 40.0 g/10 min, further from 4.0 to 30.0 g/10 min,
further from 4.0 to 20.0 g/10 min.
[0089] In one embodiment, the second ethylene-based polymer is a
polyethylene homopolymer. In a further embodiment, the polyethylene
homopolymer has a density from 0.940 to 0.985 g/cc, further from
0.945 to 0.980 g/cc, further from 0.950 to 0.975 g/cc.
[0090] In one embodiment, the second ethylene-based polymer has a
melt index from 2.0 to 500 g/10 min, further from 3.0 to 200 g/10
min, further from 4.0 to 100 g/10 min.
[0091] In one embodiment, the second ethylene-based polymer has a
melt index from 2.0 to 50.0 g/10 min, further from 3.0 to 20.0 g/10
min, further from 4.0 to 15.0 g/10 min, further from 5.0 to 10.0
g/10 min.
[0092] In one embodiment, the second composition comprises at least
one HDPE.
[0093] In one embodiment, the second composition comprises only one
HDPE and does not comprise a multimodal HDPE blend of two or more
HDPE polymers.
[0094] As used herein the term "multimodal HDPE blend" refers to a
polymer blend containing at least two HDPE polymers. Such blends
can be in-situ reactor blends formed using two or more catalyst
systems and/or two or more sets of polymerization conditions; or
can be post-reactor blends of two or more different HDPE polymers
(for example, two or more HDPE polymers that differ in one or more
of the following properties: density, melt index, Mw, Mn, MWD, or
other properties).
[0095] In a further embodiment, the second composition comprises
only one second ethylene-based polymer. In a further embodiment,
the second ethylene-based polymer is a HDPE.
[0096] In one embodiment, the second composition comprises
.gtoreq.95 wt %, further .gtoreq.98 wt %, further .gtoreq.99 wt %
of the second ethylene-based polymer, based on the weight of the
second composition. In a further embodiment, the second
ethylene-based polymer is a HDPE.
[0097] In one embodiment, the second composition comprises
.gtoreq.95 wt %, further .gtoreq.98 wt %, further .gtoreq.99 wt %
of one HDPE, based on the weight of the second composition.
[0098] In one embodiment, the second composition has a density from
0.940 to 0.966 g/cc. In a further embodiment, the second
ethylene-based polymer is a HDPE.
[0099] In one embodiment, the second composition has a
M.sub.w,cc/M.sub.n,cc from 1.5 to 5.0, or from 1.5 to 4.0, or from
1.5 to 3.5, or from 1.5 to 3.0, or from 1.5 to 2.5.
[0100] In one embodiment, the second composition has a
M.sub.w,cc/M.sub.n,cc from 1.8 to 4.0, or from 1.9 to 3.8, or from
2.0 to 3.6, or from 2.1 to 3.4.
[0101] In one embodiment, the second ethylene-based polymer has a
M.sub.w,cc/M.sub.n,cc from 1.5 to 5.0, or from 1.5 to 4.0, or from
1.5 to 3.5, or from 1.5 to 3.0, or from 1.5 to 2.5.
[0102] In one embodiment, the second ethylene-based polymer has a
M.sub.w,cc/M.sub.n,cc from 1.8 to 4.0, or from 1.9 to 3.8, or from
2.0 to 3.6, or from 2.1 to 3.4.
[0103] The second composition may comprise a combination of two or
more embodiments as described herein.
[0104] The invention also provides an article comprising at least
one component formed from an inventive composition.
[0105] In one embodiment, the article is selected from a coating, a
film, a foam, a laminate, a fiber, or a tape.
[0106] In one embodiment, the article is an extrusion coating. In
another embodiment, the article is a film.
[0107] An inventive article may comprise a combination of two or
more embodiments as described herein.
Polymerizations
[0108] For a high pressure, free radical initiated polymerization
process, two basic types of reactors are known. The first type is
an agitated autoclave vessel having one or more reaction zones (the
autoclave reactor). The second type is a jacketed tube which has
one or more reaction zones (the tubular reactor).
[0109] The pressure in each autoclave and tubular reactor zone of
the process is typically from 100 to 400, more typically from 120
to 360, and even more typically from 150 to 320 MPa.
[0110] The polymerization temperature in each tubular reactor zone
of the process is typically from 100 to 400.degree. C., more
typically from 130 to 360.degree. C., and even more typically from
140 to 330.degree. C.
[0111] The polymerization temperature in each autoclave reactor
zone of the process is typically from 150 to 300.degree. C., more
typically from 165 to 290.degree. C., and even more typically from
180 to 280.degree. C. One skilled in the art understands that the
temperatures in the autoclave are considerably lower and less
differentiated than those of the tubular reactor, and thus, more
favorable extractable levels are typically observed in polymers
produced in an autoclave-based reactor system.
[0112] The high pressure process of the present invention to
produce polyethylene homo or interpolymers having the advantageous
properties as found in accordance with the invention, is preferably
carried out in a tubular reactor having at least three reaction
zones.
Initiators
[0113] The process of the present invention is a free radical
polymerization process. The type of free radical initiator to be
used in the present process is not critical, but preferably one of
the initiators applied, should allow high temperature operation in
the range from 300.degree. C. to 350.degree. C. Free radical
initiators that are generally used include organic peroxides, such
as peresters, perketals, peroxy ketones, percarbonates and cyclic
multifunctional peroxides. These organic peroxy initiators are used
in conventional amounts, typically from 0.005 to 0.2 wt % based on
the weight of polymerizable monomers.
[0114] Other suitable initiators include azodicarboxylic esters,
azodicarboxylic dinitriles and 1,1,2,2-tetramethylethane
derivatives, and other components capable of forming free radicals
in the desired operating temperature range.
[0115] Peroxides are typically injected as diluted solutions in a
suitable solvent, for example, in a hydrocarbon solvent.
[0116] In one embodiment, an initiator is added to at least one
reaction zone of the polymerization, and wherein the initiator has
a "half-life temperature at one second" greater than 255.degree.
C., preferably greater than 260.degree. C. In a further embodiment,
such initiators are used at a peak polymerization temperature from
320.degree. C. to 350.degree. C. In a further embodiment, the
initiator comprises at least one peroxide group incorporated in a
ring structure.
[0117] Examples of such initiators include, but are not limited to,
TRIGONOX 301 (3,6,9-triethyl-3,6,9-trimethyl-1,4,7-triperoxonaan)
and TRIGONOX 311 (3,3,5,7,7-pentamethyl-1,2,4-trioxepane), both
available from Akzo Nobel, and HMCH-4-AL
(3,3,6,6,9,9-hexamethyl-1,2,4,5-tetroxonane) available from United
Initiators. See also International Publication Nos. WO 02/14379 and
WO 01/68723.
Chain Transfer Agents (CTA)
[0118] Chain transfer agents or telogens are used to control the
melt index in a polymerization process. Chain transfer involves the
termination of growing polymer chains, thus limiting the ultimate
molecular weight of the polymer material. Chain transfer agents are
typically hydrogen atom donors that will react with a growing
polymer chain and stop the polymerization reaction of the chain.
These agents can be of many different types, from saturated
hydrocarbons or unsaturated hydrocarbons to aldehydes, ketones or
alcohols. By controlling the concentration of the selected chain
transfer agent, one can control the length of polymer chains, and,
hence, the molecular weight, for example, the number average
molecular weight, Mn. The melt flow index (MFI or I.sub.2) of a
polymer, which is related to Mn, is controlled in the same way.
[0119] The chain transfer agents used in the process of this
invention include, but are not limited to, aliphatic and olefinic
hydrocarbons, such as pentane, hexane, cyclohexane, propene,
pentene or hexane; ketones such as acetone, diethyl ketone or
diamyl ketone; aldehydes such as formaldehyde or acetaldehyde; and
saturated aliphatic aldehyde alcohols such as methanol, ethanol,
propanol or butanol. The chain transfer agent may also be a
monomeric chain transfer agent. For example, see WO 2012/057975,
U.S. 61/579,067 (see International Application No. PCT/US12/068727
filed Dec. 10, 2012) and U.S. 61/664,956 (filed Jun. 27, 2012).
[0120] A further way to influence the melt index includes the build
up and control, in the ethylene recycle streams, of incoming
ethylene impurities, like methane and ethane, peroxide dissociation
products, like tert-butanol, acetone, etc., and or solvent
components used to dilute the initiators. These ethylene
impurities, peroxide dissociation products and/or dilution solvent
components can act as chain transfer agents.
Monomer and Comonomers
[0121] The term ethylene interpolymer as used in the present
description and the claims refer to polymers of ethylene and one or
more comonomers. Suitable comonomers to be used in the ethylene
polymers of the present invention include, but are not limited to,
ethylenically unsaturated monomers, and especially C.sub.3-20
alpha-olefins, In one embodiment, the ethylene-based polymer does
not contain comonomers capable of crosslinking polymer chains, for
instance comonomers containing multiple unsaturations or containing
an acetylenic functionality.
Additives
[0122] One or more additives may be added to a composition
comprising an inventive polymer. Suitable additives include
stabilizers; fillers, such as organic or inorganic particles,
including clays, talc, titanium dioxide, and silicon dioxide.
Applications
[0123] An inventive composition may be employed in a variety of
conventional thermoplastic fabrication processes to produce useful
articles, including extrusion coatings; films; and molded articles,
such as blow molded, injection molded, or rotomolded articles;
foams; wire and cable, fibers, and woven or non-woven fabrics.
Definitions
[0124] Unless stated to the contrary, implicit from the context, or
customary in the art, all parts and percents are based on weight
and all test methods are current as of the filing date of this
disclosure.
[0125] The term "composition," as used herein, refers to a mixture
of materials which comprise the composition, as well as reaction
products and decomposition products formed from the materials of
the composition.
[0126] The terms "blend" or "polymer blend," as used, mean an
intimate physical mixture (that is, without reaction) of two or
more polymers. A blend may or may not be miscible (not phase
separated at molecular level). A blend may or may not be phase
separated. A blend may or may not contain one or more domain
configurations, as determined from transmission electron
spectroscopy, light scattering, x-ray scattering, and other methods
known in the art. The blend may be effected by physically mixing
the two or more polymers on the macro level (for example, melt
blending resins or compounding) or the micro level (for example,
simultaneous forming within the same reactor).
[0127] The term "polymer" refers to a compound prepared by
polymerizing monomers, whether of the same or a different type. The
generic term polymer thus embraces the term homopolymer (which
refers to polymers prepared from only one type of monomer with the
understanding that trace amounts of impurities can be incorporated
into the polymer structure), and the term "interpolymer" as defined
infra. Trace amounts of impurities may be incorporated into and/or
within a polymer.
[0128] The term "interpolymer" refers to polymers prepared by the
polymerization of at least two different types of monomers. The
generic term interpolymer includes copolymers (which refers to
polymers prepared from two different monomers), and polymers
prepared from more than two different types of monomers.
[0129] The term "ethylene-based polymer" or "ethylene polymer"
refers to a polymer that comprises a majority amount of polymerized
ethylene based on the weight of the polymer and, optionally, may
comprise at least one comonomer.
[0130] The term "ethylene-based interpolymer" or "ethylene
interpolymer" refers to an interpolymer that comprises a majority
amount of polymerized ethylene based on the weight of the
interpolymer, and comprises at least one comonomer.
[0131] The term "ethylene-based copolymer" or "ethylene copolymer"
refers to a copolymer that comprises a majority amount of
polymerized ethylene based on the weight of the copolymer, and only
one comonomer (thus, only two monomer types).
[0132] The phrase "high pressure, free-radical polymerization
process," as used herein, refers to a free radical initiated
polymerization carried out at an elevated pressure of at least 1000
bar (100 MPa).
[0133] The terms "comprising," "including," "having," and their
derivatives, are not intended to exclude the presence of any
additional component, step or procedure, whether or not the same is
specifically disclosed. In order to avoid any doubt, all
compositions claimed through use of the term "comprising" may
include any additional additive, adjuvant, or compound, whether
polymeric or otherwise, unless stated to the contrary. In contrast,
the term, "consisting essentially of" excludes from the scope of
any succeeding recitation any other component, step or procedure,
excepting those that are not essential to operability. The term
"consisting of" excludes any component, step or procedure not
specifically delineated or listed.
Test Methods
Melt Index (I2 and I10)
[0134] Melt flow indices were measured according to ASTM Method
D1238 (Procedure B). The I2 and 110 were measured at 190.degree.
C./2.16 kg and 190.degree. C./10.0 kg, respectively.
Density
[0135] Samples for density measurement are prepared according to
ASTM D 1928. Polymer samples are pressed at 190.degree. C. and
30,000 psi (207 MPa) for three minutes, and then at 21.degree. C.
and 207 MPa for one minute. Measurements are made within one hour
of sample pressing using ASTM D792, Method B.
Triple Detector Gel Permeation Chromatography (TDGPC)--Conventional
GPC and Light Scattering GPC
[0136] For the GPC techniques used herein (Conventional GPC, Light
Scattering GPC, and gpcBR), a Triple Detector Gel Permeation
Chromatography (3D-GPC or TDGPC) system was used. This system
consisted of a PolymerChar (Valencia, Spain) GPC-IR High
Temperature Chromatograph, equipped with a Precision Detectors (Now
Agilent Technologies) 2-angle laser light scattering (LS) detector
Model 2040, an IR5 infra-red detector and 4-capillary viscometer
detector from PolymerChar. Data collection was performed using
PolymerChar "Instrument Control" software. The system was also
equipped with an on-line solvent degassing device from Agilent
Technologies (CA, USA).
[0137] The eluent from the GPC column set flowed through each
detector arranged in series, in the following order: IRS detector,
LS detector, then the Viscometer detector. The systematic approach
for the determination of multi-detector offsets was performed in a
manner consistent with that published by Balke, Mourey, et al.
(Mourey and Balke, Chromatography Polym., Chapter 12, (1992))
(Balke, Thitiratsakul, Lew, Cheung, Mourey, Chromatography Polym.,
Chapter 13, (1992)), optimizing triple detector log (MW and
intrinsic viscosity) results from using a broad polyethylene
standard, as outlined in the section on Light Scattering (LS) GPC
below, in the paragraph following Equation (5).
[0138] Four 20-micron mixed-pore-size packing ("Mixed A", Agilent
Technologies) are used for the separation. The PolymerChar
Autosampler oven compartment was operated at 160.degree. C. with
low speed shaking for 3 hours, and the column compartment was
operated at 150.degree. C. The samples were prepared at a
concentration of "2 milligrams per milliliter." The chromatographic
solvent and the sample preparation solvent was
1,2,4-trichlorobenzene (TCB) containing "200 ppm of
2,6-di-tert-butyl-4methylphenol (BHT)." The solvent was sparged
with nitrogen. The injection volume was 200 microliters. The flow
rate through the GPC was set at 1 ml/minute. For this study,
conventional GPC data and light scattering GPC data were
recorded.
Conventional GPC
[0139] For Conventional GPC, the IR5 detector ("measurement
sensor") was used, and the GPC column set was calibrated by running
21 narrow molecular weight distribution polystyrene standards. The
molecular weight (MW) of the standards ranged from 580 g/mol to
8,400,000 g/mol, and the standards were contained in 6 "cocktail"
mixtures. Each standard mixture had at least a decade of separation
between individual molecular weights. The standard mixtures were
purchased from Polymer Laboratories (now Agilent Technologies). The
polystyrene standards were prepared at "0.025 g in 50 mL of
solvent" for molecular weights equal to, or greater than, 1,000,000
g/mol, and at "0.05 g in 50 mL of solvent" for molecular weights
less than 1,000,000 g/mol. The polystyrene standards were dissolved
at 80.degree. C., with gentle agitation, for 30 minutes. The narrow
standards mixtures were run first, and in order of decreasing
highest molecular weight component, to minimize degradation. The
polystyrene standard peak molecular weights were converted to
polyethylene molecular weight using Equation (1) (as described in
Williams and Ward, J. Polym. Sci., Polym. Letters, 6, 621
(1968)):
MW.sub.PE=A.times.(MW.sub.PS).sup.B (Eq. 1)
where MW is the molecular weight of polyethylene (PE) or
polystyrene (PS) as marked, and B is equal to 1.0. It is known to
those of ordinary skill in the art that A may be in a range of
about 0.38 to about 0.44 such that the A value yields 52,000
MW.sub.PE for Standard Reference Materials (SRM) 1475a. Use of this
polyethylene calibration method to obtain molecular weight values,
such as the molecular weight distribution (MWD or Mw/Mn), and
related statistics, is defined here as the modified method of
Williams and Ward. The number average molecular weight, the weight
average molecular weight, and the z-average molecular weight are
calculated from the following equations.
M.sub.n,cc=.SIGMA.w.sub.i/.SIGMA.(w.sub.i/M.sub.cc,i) (Eq. 2)
M.sub.w,cc=.SIGMA.w.sub.iM.sub.cc,i (Eq. 3)
M.sub.z,cc=.SIGMA.(w.sub.iM.sub.cc,i.sup.2)/.SIGMA.(w.sub.iM.sub.cc,i)
(Eq. 4)
[0140] where M.sub.n,cc, M.sub.w,cc, and M.sub.z,cc are the
number-, weight-, and z-average molecular weight obtained from the
conventional calibration, respectively. w.sub.i is the weight
fraction of the polyethylene molecules eluted at retention volume
V.sub.i. M.sub.cc,i is the molecular weight of the polyethylene
molecules eluted at retention volume V.sub.i obtained using the
conventional calibration (see Equation (1)).
Light Scattering (LS) GPC
[0141] For the LS GPC, the Precision Detector PDI2040 detector
Model 2040 15.degree. angle was used. The molecular weight data was
obtained in a manner consistent with that published by Zimm (Zimm,
B. H., J. Chem. Phys., 16, 1099 (1948)) and Kratochvil (Kratochvil,
P., Classical Light Scattering from Polymer Solutions, Elsevier,
Oxford, NY (1987)). The overall injected concentration, used in the
determination of the molecular weight, was obtained from the mass
detector (IR5) area, and the mass detector constant, derived from a
suitable linear polyethylene homopolymer, or one of the
polyethylene standards of known weight-average molecular weight.
The calculated molecular weights were obtained using a light
scattering constant, derived from one or more of the polyethylene
standards mentioned below, and a refractive index concentration
coefficient, do/dc, of 0.104. Generally, the mass detector response
and the light scattering constant should be determined from a
linear standard with a molecular weight in excess of about 50,000
g/mole. The viscometer calibration can be accomplished using the
methods described by the manufacturer, or, alternatively, by using
the published values of suitable linear standards, such as Standard
Reference Materials (SRM) 1475a (available from National Institute
of Standards and Technology (NIST)). The chromatographic
concentrations are assumed low enough to eliminate addressing 2nd
viral coefficient effects (concentration effects on molecular
weight).
[0142] With 3D-GPC, absolute weight-average molecular weight
"M.sub.w,abs") (and absolute z-average molecular weight
("M.sub.z,abs") is determined using Equations (5) and (6) below,
using the "peak area" method (after detector calibration relating
areas to mass and mass-molecular weight product) for higher
accuracy and precision. The "LS.Area" and the "Concentration.Area"
are generated by the chromatograph/detectors combination.
M w , abs = C i M abs , i C i = LS i C i = LS . Area Concentration
. Area ( Eq . 5 ) M z , abs = ( w i M abs , i 2 ) / ( w i M abs , i
) ( Eq . 6 ) ##EQU00001##
where C.sub.i is the concentration of the polyethylene molecules in
the eluant at the retention volume V.sub.i, M.sub.abs,i is the
absolute molecular weight of the polyethylene molecules at the
retention volume V.sub.i, .SIGMA.LS.sub.i (LS.Area) is the total
response of the light scattering, and the .SIGMA.C.sub.i
(Concentration.Area) is the total concentration.
[0143] For each LS profile, the x-axis (log MW.sub.cc-GPC), where
cc refers to the conventional calibration curve, is determined as
follows. First, the polystyrene standards (see above) are used to
calibrate the retention volume into "log MW.sub.PS." Then, Equation
(1) (MW.sub.PE=A.times.(MW.sub.PS).sup.B) is used to convert "log
MW.sub.PS" to "log MW.sub.PE" The "log MW.sub.PE" scale serves as
the x-axis for the LS profiles of the experimental section (log
MW.sub.PE is equated to the log MW(cc-GPC)). The y-axis for each LS
profile is the LS detector response normalized by the injected
sample mass. Initially, the molecular weight and intrinsic
viscosity for a linear homopolymer polyethylene standard sample,
such as SRM1475a or an equivalent, are determined using the
conventional calibrations ("cc") for both molecular weight and
intrinsic viscosity as a function of elution volume.
[0144] In the low molecular weight region of the GPC elution curve,
the presence of a significant peak that is known to be caused by
the presence of anti-oxidant or other additives, will cause an
underestimation of the number average molecular weight (Mn) of the
polymer sample, to give a overestimation of the sample
polydispersity, defined as Mw/Mn, where Mw is the weight average
molecular weight. The true polymer sample molecular weight
distribution can therefore be calculated from the GPC elution by
excluding this extra peak. This process is commonly described as
the peak skim feature in data processing procedures in liquid
chromatographic analyses. In this process, this additive peak is
skimmed off from the GPC elution curve before the sample molecular
weight calculation is performed from the GPC elution curve.
gpcBR Branching Index by Triple Detector GPC (3D-GPC)
[0145] The gpcBR branching index is determined by first calibrating
the light scattering, viscosity, and concentration detector (IR5)
as described previously. Baselines are then subtracted from the
light scattering, viscometer, and concentration chromatograms.
Integration windows are then set to ensure integration of all of
the low molecular weight retention volume range in the light
scattering and viscometer chromatograms that indicate the presence
of detectable polymer from the infrared (IR5) chromatogram. Linear
polyethylene standards are then used to establish polyethylene and
polystyrene Mark-Houwink constants. Upon obtaining the constants,
the two values are used to construct two linear reference
conventional calibrations for polyethylene molecular weight
(M.sub.PE) and polyethylene intrinsic viscosity ([.eta.].sub.PE) as
a function of elution volume, as shown in Equations (7) and
(8):
M.sub.PE=(K.sub.PS/K.sub.PE).sup.1/(.alpha.PE+1)M.sub.PS.sup.(.alpha..su-
p.PS.sup.+1)/(.alpha..sup.PE.sup.+1) (Eq. 7
[.eta.].sub.PE=K.sub.PSM.sub.PS.sup..alpha..sup.PS.sup.+1/M.sub.PE
(Eq. 8)
where M.sub.PS is the molecular weight of polystyrene.
[0146] The gpcBR branching index is a robust method for the
characterization of long chain branching as described in Yau,
Wallace W., "Examples of Using 3D-GPC-TREF for Polyolefin
Characterization," Macromol. Symp., 2007, 257, 29-45. The index
avoids the "slice-by-slice" 3D-GPC calculations traditionally used
in the determination of g' values and branching frequency
calculations, in favor of whole polymer detector areas. From 3D-GPC
data, one can obtain the sample bulk absolute weight average
molecular weight (M.sub.w, abs) by the light scattering (LS)
detector, using the peak area method. The method avoids the
"slice-by-slice" ratio of light scattering detector signal over the
concentration detector signal, as required in a traditional g'
determination.
[0147] With 3D-GPC, sample intrinsic viscosities are also obtained
independently using Equations (9). The area calculation in
Equations (5) and (9) offers more precision, because, as an overall
sample area, it is much less sensitive to variation caused by
detector noise and 3D-GPC settings on baseline and integration
limits. More importantly, the peak area calculation is not affected
by the detector volume offsets. Similarly, the high-precision
sample intrinsic viscosity (IV) is obtained by the area method
shown in Equation (9):
IV w = C i IV i C i = .eta. sp , i C i = Viscometer . Area
Concentration . Area ( Eq . 9 ) ##EQU00002##
where .eta..sub.sp,i stands for the specific viscosity as acquired
from the viscometer detector.
[0148] To determine the gpcBR branching index, the light scattering
elution area for the sample polymer is used to determine the
molecular weight of the sample. The viscosity detector elution area
for the sample polymer is used to determine the intrinsic viscosity
(IV or [.eta.]) of the sample.
[0149] Initially, the molecular weight and intrinsic viscosity for
a linear polyethylene standard sample, such as SRM1475a or an
equivalent, are determined using the conventional calibrations
("cc") for both molecular weight and intrinsic viscosity as a
function of elution volume, per Equations (2) and (10):
IV cc = C i IV i , cc C i = C i K ( M i , cc ) .alpha. PE C i ( Eq
. 10 ) ##EQU00003##
[0150] Equation (11) is used to determine the gpcBR branching
index:
gpcBR = ( IV cc IV w ) ( M w , abs M w , cc ) .alpha. PE - 1 ( Eq .
11 ) ##EQU00004##
wherein IV.sub.w is the measured intrinsic viscosity, IV.sub.cc is
the intrinsic viscosity from the conventional calibration,
M.sub.w,abs is the measured absolute weight average molecular
weight, and M.sub.w,cc is the weight average molecular weight from
the conventional calibration. The weight average molecular weight
by light scattering (LS) using Equation (5) is commonly referred to
as "absolute weight average molecular weight" or "M.sub.w, abs."
The M.sub.w, cc from Equation (2) using conventional GPC molecular
weight calibration curve ("conventional calibration") is often
referred to as "polymer chain backbone molecular weight,"
"conventional weight average molecular weight," and
"M.sub.w,cc."
[0151] All statistical values with the "cc" subscript are
determined using their respective elution volumes, the
corresponding conventional calibration as previously described, and
the concentration (C.sub.i). The non-subscripted values are
measured values based on the mass detector, LALLS (Low Angle Laser
Light Scattering--15 degree signal), and viscometer areas. The
value of K.sub.PE is adjusted iteratively, until the linear
reference sample has a gpcBR measured value of zero. For example,
the final values for .alpha. and Log K for the determination of
gpcBR in this particular case are 0.725 (.alpha..sub.PE) and -3.391
(log K.sub.PE), respectively, for polyethylene, and 0.722
(.alpha..sub.PS) and -3.993 (log K.sub.PS), respectively, for
polystyrene. These polyethylene coefficients (a and K) were then
entered into Equation (10).
[0152] Once the K and .alpha. values have been determined using the
procedure discussed previously, the procedure is repeated using the
branched samples. The branched samples are analyzed using the final
Mark-Houwink constants obtained from the linear reference as the
best "cc" calibration values, and Equations (2)-(10) are
applied.
[0153] The interpretation of gpcBR is straight-forward. For linear
polymers, gpcBR calculated from Equation (11) will be close to
zero, since the values measured by LS and viscometry will be close
to the conventional calibration standard. For branched polymers,
gpcBR will be higher than zero, especially with high levels of long
chain branching, because the measured polymer molecular weight will
be higher than the calculated M.sub.w,cc, and the calculated IVcc
will be higher than the measured polymer IV. In fact, the gpcBR
value represents the fractional IV change due the molecular size
contraction effect as the result of polymer branching. A gpcBR
value of 0.5 or 2.0 would mean a molecular size contraction effect
of IV at the level of 50% and 200%, respectively, versus a linear
polymer molecule of equivalent weight.
[0154] For these particular examples, the advantage of using gpcBR,
in comparison to a traditional "g' index" and branching frequency
calculations, is due to the higher precision of gpcBR. All of the
parameters used in the gpcBR index determination are obtained with
good precision, and are not detrimentally affected by the low
3D-GPC detector response at high molecular weight from the
concentration detector. Errors in detector volume alignment also do
not affect the precision of the gpcBR index determination.
Differential Scanning Calorimetry (DSC)
[0155] DSC was used to measure the melting and crystallization
behavior of a polymer over a wide range of temperatures. For
example, the TA Instruments Q1000 DSC, equipped with an RCS
(refrigerated cooling system) and an autosampler was used to
perform this analysis. During testing, a nitrogen purge gas flow of
50 ml/min was used. Each sample was melt pressed into a thin film
at about 175.degree. C.; the melted sample was then air-cooled to
room temperature (approx. 25.degree. C.). The film sample was
formed by pressing a "0.1 to 0.2 gram" sample at 175.degree. C. at
1,500 psi, and 30 seconds, to form a "0.1 to 0.2 mil thick" film. A
3-10 mg, 6 mm diameter specimen was extracted from the cooled
polymer, weighed, placed in a light aluminum pan (ca 50 mg), and
crimped shut. Analysis was then performed to determine its thermal
properties.
[0156] The thermal behavior of the sample was determined by ramping
the sample temperature up and down to create a heat flow versus
temperature profile. First, the sample was rapidly heated to
180.degree. C., and held isothermal for five minutes, in order to
remove its thermal history. Next, the sample was cooled to
-40.degree. C., at a 10.degree. C./minute cooling rate, and held
isothermal at -40.degree. C. for five minutes. The sample was then
heated to 150.degree. C. (this is the "second heat" ramp) at a
10.degree. C./minute heating rate. The cooling and second heating
curves were recorded. The cool curve was analyzed by setting
baseline endpoints from the beginning of crystallization to
-20.degree. C. The heat curve was analyzed by setting baseline
endpoints from -20.degree. C. to the end of melt. The values
determined were peak melting temperature (T.sub.m), peak
crystallization temperature (T.sub.a), heat of fusion (H.sub.f) (in
Joules per gram), and the calculated % crystallinity for
polyethylene samples using: % Crystallinity=((H.sub.f)/(292
J/g)).times.100.
[0157] The heat of fusion (H.sub.f) and the peak melting
temperature were reported from the second heat curve. Peak
crystallization temperature is determined from the cooling
curve.
Rheology Measurement
[0158] The test sample used in the rheology measurement was
prepared from a compression molding plaque. A piece of aluminum
foil was placed on a back plate, and a template or mold was placed
on top of the back plate. Approximately 3.2 grams of resin was
placed in the mold, and a second piece of aluminum foil was placed
over the resin and mold. A second back plate was then placed on top
of the aluminum foil. The total ensemble was put into a compression
molding press and pressed for 6 min at 190.degree. C. under 25000
psi. The sample was then removed and laid on the counter to cool to
room temperature. A 25 mm disk was stamped out of the
compression-molded plaque. The thickness of this disk was
approximately 3.0 mm.
[0159] The rheology measurement to determine DMS G'(at G''=500 Pa,
170.degree. C.) was done in a nitrogen environment, at 170.degree.
C., and a strain of 10%. The stamped-out disk was placed between
the two "25 mm" parallel plates located in an ARES-1 (Rheometrics
SC) rheometer oven, which was preheated, for at least 30 minutes,
at 170.degree. C., and the gap of the "25 mm" parallel plates was
slowly reduced to 2.0 mm. The sample was then allowed to remain for
exactly 5 minutes at these conditions. The oven was then opened,
the excess sample was carefully trimmed around the edge of the
plates, and the oven was closed. The method had an additional five
minute delay built in, to allow for temperature equilibrium. Then
the storage modulus and loss modulus of the sample were measured
via a small amplitude, oscillatory shear, according to a decreasing
frequency sweep from 100 to 0.1 rad/s (when able to obtain a G''
value lower than 500 Pa at 0.1 rad/s), or from 100 to 0.01 rad/s.
For each frequency sweep, 10 points (logarithmically spaced) per
frequency decade were used.
[0160] The data were plotted (G' (Y-axis) versus G'' (X-axis)) on a
log-log scale, and fitted to a 4.sup.th-order polynomial curve (log
G'=a+b.times.log G''+c.times.(log G'').sup.2+d.times.(log
G'').sup.3+ex(log G'').sup.4, where a, b, c, d and e are constants
determined by the least square fitting method). G' (at G''=500 Pa,
170.degree. C.) was obtained from the fitted equation.
[0161] The rheology measurement to determine the viscosity at 0.1
rad/s, the viscosity at 100 rad/s, tan delta at 0.1 rad/s, tan
delta at 100 rad/s, and G' (at G''=5 kPa, 190.degree. C.) was done
in a nitrogen environment, at 190.degree. C., and a strain of 10%.
The stamped-out disk was placed between the two "25 mm" parallel
plates located in an ARES-1 (Rheometrics SC) rheometer oven, which
was preheated, for at least 30 minutes, at 190.degree. C., and the
gap of the "25 mm" parallel plates was slowly reduced to 2.0 mm.
The sample was then allowed to remain for exactly 5 minutes at
these conditions. The oven was then opened, the excess sample was
carefully trimmed around the edge of the plates, and the oven was
closed. The method had an additional five minute delay built in, to
allow for temperature equilibrium. Then the viscosity at 0.1 rad/s,
viscosity at 100 rad/s, tan delta at 0.1 rad/s and tan delta at 100
rad/s were measured via a small amplitude, oscillatory shear,
according to an increasing frequency sweep from 0.1 to 100 rad/s.
The complex viscosity .eta.*, tan (.delta.) or tan delta, viscosity
at 0.1 rad/s (V0.1), the viscosity at 100 rad/s (V100), and the
viscosity ratio (V0.1/V100) were calculated from these data.
[0162] For G' (at G''=5 kPa, 190.degree. C.), the data were plotted
(G' (Y-axis) versus G'' (X-axis)) on a log-log scale, and fitted to
a 4.sup.th-order polynomial curve (log G'=a'+b'.times.log
G''+c'.times.(log G'').sup.2+d'.times.(log G'').sup.3+e'.times.(log
G'').sup.4, where a', b', c', d' and e' are constants determined by
the least square fitting method). G' (at G''=5 kPa, 190.degree. C.)
was obtained from the fitted equation
Melt Strength
[0163] Melt strength was measured at 190.degree. C. using a
Goettfert Rheotens 71.97 (Goettfert Inc.; Rock Hill, S.C.), melt
fed with a Goettfert Rheotester 2000 capillary rheometer equipped
with a flat entrance angle (180 degrees) of length of 30 mm and
diameter of 2.0 mm. The pellets (20-30 gram pellets) were fed into
the barrel (length=300 mm, diameter=12 mm), compressed and allowed
to melt for 10 minutes before being extruded at a constant piston
speed of 0.265 mm/s, which corresponds to a wall shear rate of 38.2
s.sup.-1 at the given die diameter. The extrudate passed through
the wheels of the Rheotens located 100 mm below the die exit and
was pulled by the wheels downward at an acceleration rate of 2.4
mm/s.sup.2. The force (in cN) exerted on the wheels was recorded as
a function of the velocity of the wheels (in mm/s). Melt strength
is reported as the plateau force (cN) before the strand broke.
Standard Method for Hexane Extractables
[0164] Hexane Extractables--Polymer pellets (from the
polymerization pelletization process without further modification;
approximately 2.2 grams (pellets) per press) were pressed in a
Carver Press at a thickness of 2.5-3.5 mils. The pellets were
pressed at 190.degree. C. and 3000 lbf for three minutes, and then
at 190.degree. C. and 40000 lbf for another three minutes.
Non-residue gloves (PIP*CleanTeam*CottonLisle Inspection Gloves,
Part Number: 97-501) were worn to prevent contamination of the
films with residual oils from the hands of the operator. Films were
cut into "1-inch by 1-inch" squares, and weighed (2.5.+-.0.05 g).
The films were extracted for two hours, in a hexane vessel,
containing about 1000 ml of hexane, at 49.5.+-.0.5.degree. C., in a
heated water bath. The hexane used was an isomeric "hexanes"
mixture (for example, Hexanes (Optima), Fisher Chemical, high
purity mobile phase for HPLC and/or extraction solvent for GC
applications). After two hours, the films were removed, rinsed in
clean hexane, and dried in a vacuum oven (80.+-.5.degree. C.), at
full vacuum (ISOTEMP Vacuum Oven, Model 281A, at approximately 30
inches Hg) for two hours. The films were then place in a
desiccators, and allowed to cool to room temperature for a minimum
of one hour. The films were then reweighed, and the amount of mass
loss due to extraction in hexane was calculated. This method was
based on 21 CRF 177.1520 (d)(3)(ii), with one deviation from FDA
protocol by using hexanes instead of n-hexane.
Extrusion Coating
[0165] All coating experiments were performed on a Black-Clawson
Extrusion Coating Line. The extruder was equipped with a 31/2 inch,
30:1 L/D, 4:1 compression ratio single flight screw with two spiral
Mattock mixing sections. The nominal die width of 91 cm (36 inches)
was deckled (metal dam to block the flow in the die at the die exit
around the outer edges of the die, and used to decrease the die
width, and thus decrease the polymer flow out of the die) to an
open die width of 61 cm (24 inches). In extrusion coating, a deckle
is a die insert that sets the coating width of a slot die coater or
the extrusion width of an extrusion die. It work by constraining
the flow as the material exits the die.
[0166] Die gap was 25 mil, and the air gap was *15 cm (6 inches).
Blends of the various components were produced by weighing out the
pellets, and then tumble blending samples, until a homogeneous
blend was obtained (approximately 30 minutes for each sample). The
temperatures in each zone of the extruder were 177, 232, 288, and
316.degree. C. (die) (350, 450, 550 and 600.degree. F. (die)),
respectively, leading to a target melt temperature of 316.degree.
C. (600.degree. F.). The screw speed was 90 rpm, resulting in 250
lb/hr output rate. Line speed was at 440 ft/min (fpm) resulting in
a 1 mil coating onto a 50 lb/ream KRAFT paper (the width of the
KRAFT paper was 61 cm (24 inches); unbleached). The coated paper
was used for heat seal testing (polymer coating/KRAFT paper
configuration). In order to obtain a piece of polymer film for the
water vapor transmission rate (WVTR) test, a piece of release liner
(width of release liner about 61 cm was inserted between the
polymer coating and the paper substrate before the molten polymer
curtain touched the paper substrate, to form a "polymer
coating/release liner/KRAFT paper" configuration. The solidified
polymer coatings were then released from the release liner for the
WVTR test.
[0167] The amount of neck-in (the difference in actual coating
width versus deckle width (61 cm)) was measured at line speeds of
440 feet per min and 880 feet per minute (fpm), resulting in a "1
mil" and a "0.5 mil" coating thickness, respectively. Amperage and
Horse Power of the extruder were recorded. The amount of backpres
sure was also recorded for each polymer, without changing the back
pressure valve position. Draw down is the speed at which edge
imperfections on the polymer coating (typically the width of the
polymer coating oscillating along the edges of the polymer coating)
were noticed, or that speed at which the molten curtain completely
tears from the die. Although the equipment is capable of haul-off
speeds of 3000 fpm, for these experiments the maximum speed used
was 1500 fpm. Draw down was measured at 90 rpm screw speed. If no
imperfections and/or polymer tear were observed at 1500 fpm, the
output rate was reduced by slowing the screw speed down to 45 rpm.
The reduced rate draw down was then recorded at 45 rpm screw speed.
Extrusion coating results are shown in the experimental
section.
Water Vapor Transmission Rate (WVTR)
[0168] Polymer films released from the release liner, prepared from
the extrusion coating experiment at 440 fpm, were used for WVTR
study. Films were cut into "9 cm.times.10 cm" test sample. Each
polymer coating was around 1 mil in thickness. WVTR was measured
with a Mocon W3/33 according to ASTM F1249-06, at 38.degree. C.,
with 100% relative humidity (RH). The average value of two
replicates was reported. WVTR results are shown in below in the
experimental section.
Heat Seal
[0169] The coated paper obtained from extrusion coating experiment,
at 440 fpm was used for heat seal test. The polymer coating layer
thickness was around 1 mil. Each coated paper for this study was
conditioned for 40 hours in ASTM conditions (23.+-.2.degree. C. and
50.+-.10% relative humidity). For each composition, two coated
paper sheets were placed together, with the polymer coating on one
sheet in contact with the polymer coating of the other sheet
(paper/polymer coating/polymer coating/paper configuration) to form
a pre-sealed sheet.
[0170] Each samples was sealed with Kopp Heat Sealer using a
standard sealing temperatures ranging from 80.degree. C. to
150.degree. C., in 10.degree. C. increments, to form a heat sealed
sample sheet. The width of the seal bar was 5 mm. Each pre-sealed
sheet was sealed in the cross direction at 39 psi, with a dwell
time of 0.5 sec, to form a sealed sample sheet.
[0171] Each sealed sample sheet was cut into "1 inch width" strips
using a compressed air sample cutter, along the machine direction
of the sheet, to form five test specimens. Each test specimen had a
width of one inch, and a length of four inches. A bonded area of "1
inch.times.5 mm" was located at distance of about one inch from one
end of the test specimen.
[0172] Each test sample was then conditioned for 40 hours (in ASTM
conditions (23.+-.2.degree. C. and 50.+-.10% relative humidity))
before being tested. Each sample was tested using an MTS Universal
Tensile Testing Machine with a 50 lb load cell, and was pulled at a
rate of 10 in/min, until failure. See FIG. 6--free ends of each
test sample, further from the bonded area, were clamped into the
MTS Universal Tensile Testing Machine. Test temperature and peak
load average (from five replicate test samples) per sealing
temperature were reported.
EXPERIMENTAL
I. Resins and Material
LDPE-1
[0173] For LDPE-1, the polymerization was carried out in tubular
reactor with four reaction zones. In each reaction zone,
pressurized water was used for cooling and/or heating the reaction
medium, by circulating this water countercurrent through the jacket
of the reactor. The inlet-pressure was 2150 bar. The ethylene
throughput was about 45 t/h. Each reaction zone had one inlet and
one outlet. Each inlet stream consisted of the outlet stream from
the previous reaction zone and/or an added ethylene-rich feed
stream. The ethylene was supplied according to a specification,
which allowed a trace amount (maximum of 5 mol ppm) of acetylene in
the ethylene. Thus, the maximum, potential amount of incorporated
acetylene in the polymer is less than, or equal to, 16 mole ppm,
based on the total moles of monomeric units in the ethylene-based
polymer. The non-converted ethylene, and other gaseous components
in the reactor outlet, were recycled through a high pressure and a
low pressure recycles, and were compressed through a booster, a
primary and a hyper (secondary) compressor. Organic peroxides (see
Table 1) were fed into each reaction zone. For this polymerization,
both propionaldehyde (PA) and n-butane were used as a chain
transfer agent, and were present in each reaction zone. The
ethylene rich reactor feed streams contain even concentrations of
the applied chain transfer agents.
[0174] After reaching the first peak temperature (maximum
temperature) in reaction zone 1, the reaction medium was cooled
with the aid of the pressurized water. At the outlet of reaction
zone 1, the reaction medium was further cooled by injecting a
fresh, cold, ethylene-rich feed stream, containing organic peroxide
for re-initiation. At the end of the second reaction zone, to
enable further polymerization in the third reaction zone, organic
peroxides were fed. This process was repeated at the end of the
third reaction zone, to enable further polymerization in the fourth
reaction zone. The polymer was extruded and pelletized (about 30
pellets per gram), using a single screw extruder design, at a melt
temperature around 230-250.degree. C. The weight ratio of the
ethylene-rich feed streams in the four reaction zones was
X:(1.00-X):0.00:0.00, where X is the weight fraction of the overall
ethylene rich feed stream, X is specified in Table 3 as "Ethylene
to the front/wt %". The internal process velocity was approximately
15, 13, 12 and 12 m/sec for respectively the 1st, 2nd, 3rd and 4th
reaction zone. Additional information can be found in Tables 2 and
3.
TABLE-US-00001 TABLE 1 Initiators for the LDPE-1 Initiator
Abbreviation tert-Butyl peroxy-2-ethyl hexanoate TBPO Di-tert-butyl
peroxide DTBP
TABLE-US-00002 TABLE 2 Pressure and Temperature Conditions for the
LDPE-1 Reinitiation 1st 2nd 3rd 4th Inlet- Start- temp.
Reinitiation Reinitiation Peak Peak Peak Peak pressure/ temp./ 2nd
zone/ temp. temp. temp./ temp./ temp./ temp./ bar .degree. C.
.degree. C. 3rd zone/.degree. C. 4rd zone/.degree. C. .degree. C.
.degree. C. .degree. C. .degree. C. LDPE- 2150 152 183 248 253 319
314 314 301 1
TABLE-US-00003 TABLE 3 Additional Information of LDPE-1 Make-up
flow ratio by weight Ethylene to the Peroxides CTA PA/n-butane
front/wt % LDPE-1 TBPO/DTBP PA/n-butane 1.0 47
HDPE 1-5
[0175] For HDPE-1 through HDPE-5, all raw materials (monomer and
comonomer) and the process solvent (a narrow boiling range,
high-purity isoparaffinic solvent) were purified with molecular
sieves, before introduction into the reaction environment. Hydrogen
was supplied in pressurized cylinders, as a high purity grade, and
was not further purified. The reactor monomer feed stream was
pressurized, via a mechanical compressor, to above reaction
pressure. The solvent and comonomer feed was pressurized, via a
pump, to above reaction pressure. The individual catalyst
components were manually batch diluted with purified solvent, and
pressured to above reaction pressure. All reaction feed flows were
measured with mass flow meters, and independently controlled with
computer automated valve control systems. The fresh comonomer feed
(if required) was mechanically pressurized and injected into the
feed stream for the reactor.
[0176] The continuous solution polymerization reactor consisted of
a liquid full, non-adiabatic, isothermal, circulating, loop
reactor, which is similar a continuously stirred tank reactor
(CSTR) with heat removal. Independent control of all fresh solvent,
monomer, comonomer, hydrogen, and catalyst component feeds was
possible. The total fresh feed stream to the reactor (solvent,
monomer, comonomer, and hydrogen) was temperature controlled, by
passing the feed stream through a heat exchanger. The total fresh
feed to the polymerization reactor was injected into the reactor at
two locations, with approximately equal reactor volumes between
each injection location. The fresh feed was controlled, with each
injector receiving half of the total fresh feed mass flow.
[0177] The catalyst components were injected into the
polymerization reactor, through a specially designed injection
stinger, and were combined into one mixed catalyst/cocatalyst feed
stream, prior to injection into the reactor. The primary catalyst
component feed was computer controlled, to maintain the reactor
monomer conversion at a specified target. The cocatalyst components
were fed, based on calculated specified molar ratios to the primary
catalyst component. Immediately following each fresh injection
location (either feed or catalyst), the feed streams were mixed,
with the circulating polymerization reactor contents, with static
mixing elements. The contents of the reactor were continuously
circulated through heat exchangers, responsible for removing much
of the heat of reaction, and with the temperature of the coolant
side, responsible for maintaining an isothermal reaction
environment at the specified temperature. Circulation around the
reactor loop was provided by a pump. The final reactor effluent
entered a zone, where it was deactivated with the addition of, and
reaction with, a suitable reagent (water). At this same reactor
exit location, other additives may also be added.
[0178] Following catalyst deactivation and additive addition, the
reactor effluent entered a devolatization system, where the polymer
was removed from the non-polymer stream. The isolated polymer melt
was pelletized and collected. The non-polymer stream passed through
various pieces of equipment, which separate most of the ethylene,
which was removed from the system. Most of the solvent and
unreacted comonomer was recycled back to the reactor, after passing
through a purification system. A small amount of solvent and
comonomer was purged from the process. The process conditions in
the reactor are summarized in Table 4 and Table 5.
TABLE-US-00004 TABLE 4 Catalyst information CAS name Cat. A
(tert-butyl(dimethyl(3-(pyrrolidin-1-yl)-1H-inden-
1-yl)silyl)amino)dimethyltitanium Co-Cat. B Amines,
bis(hydrogenated tallow alkyl)methyl,
tetrakis(pentafluorophenyl)borate(1-) Co-Cat. C Aluminoxanes,
iso-Bu Me, branched, cyclic and linear; modified methyl 3A
aluminoxane
TABLE-US-00005 TABLE 5 Process conditions to produce high density
polyethylenes Sample # HDPE-1 HDPE-2 HDPE-3 HDPE-4 HDPE-5 Reactor
Single Single Single Single Single Configuration Units Reactor
Reactor Reactor Reactor Reactor Comonomer 1-octene none none none
none Reactor Total lb/hr 2746 1986 2777 2381 2775 Solvent Flow
Reactor Total lb/hr 407 391 413 354 411 Ethylene Flow Reactor Total
lb/hr 18 0 0 0 0 Comonomer Flow Reactor Hydrogen SCCM 9088 8498
19067 4659 8998 Feed Flow Reactor Control .degree. C. 142 167 160
150 150 Temperature Reactor Ethylene % 85.5 89.9 85.3 85.5 84.1
Conversion Reactor Viscosity centi-Poise 82 10 8 223 66 Reactor
Catalyst type Cat. A Cat. A Cat. A Cat. A Cat. A Reactor
Co-catalyst 1 type Co-Cat. B Co-Cat. B Co-Cat. B Co-Cat. B Co-Cat.
B Reactor Co-catalyst 2 type Co-Cat. C Co-Cat. C Co-Cat. C Co-Cat.
C Co-Cat. C Reactor Catalyst g Polymer/g 5452000 865000 3239000
6362000 4956000 Efficiency catalyst metal Reactor Ratio 1.4 1.1 1.4
1.4 1.4 Cocatalyst to Catalyst Metal Molar Ratio Reactor Scavenger
Ratio 8.0 5.0 8.0 8.0 8.0 to Catalyst Metal Molar Ratio
[0179] Polymers are typically stabilized with minor amounts (ppm)
of one or more stabilizers. Polymers, and associated properties,
are listed in Tables 6 and 7 below.
TABLE-US-00006 TABLE 6 Density and Melt Index of LDPE resins and
HDPE Resins I2 I10 DMS G' DMS G' Density (g/10 (g/10 (at G'' = 5
kPa) (at G'' = 500 Pa) (g/cc) min) min) (Pa) @ 190.degree. C. (Pa)
@ 170.degree. C. LDPE-1 0.9194 6.9 81.9 3500 129 (tubular) LDPE-2
0.9192 4.6 NM 3908 156 (tubular)* AGILITY 0.9190 3.9 NM 3936 156 EC
7000 (tubular) HDPE-1 0.9462 4.3 24.9 NM NM HDPE-2 0.9563 20.2 133
NM NM HDPE-3 0.9654 62 384 NM NM HDPE-4 0.9567 1.0 6.4 NM NM HDPE-5
0.9576 4.9 28.42 NM NM HDPE-6* 0.9543 9.8 NM NM NM HDPE-7* 0.9571
2.0 NM NM NM HDPE 0.9630 10 NM NM NM 10462N *LDPE-2 is a melt blend
of AGILITY EC 7000 and LDPE-1 in 50%/50% by weight. *HDPE-6 is a
melt blend of HDPE-1 and HDPE-2 in 40%/60% by weight. *HDPE-7 is a
melt blend of HDPE-4 and HDPE-5 in 50%/50% by weight. NM = Not
Measured
TABLE-US-00007 TABLE 7 Molecular Weights and Molecular Weight
Distribution of the HDPE resins - conventional calibration from
Triple Detector GPC M.sub.n,cc M.sub.w,cc M.sub.z,cc (g/mol)
(g/mol) (g/mol) M.sub.w,cc/M.sub.n,cc HDPE-1 34,134 72,540 125,343
2.13 HDPE-2 19,654 46,383 83,398 2.36 HDPE-3 16,855 36,643 61,025
2.17 HDPE-4 48,112 104,138 184,869 2.16 HDPE-6 21,423 51,564 95,630
2.41 HDPE-7 40,163 87,777 159,201 2.19 HDPE 10462N 19,369 63,741
215,413 3.29
II. Compositions
[0180] Melt blend samples (compositions) were generated in a 30 mm
co-rotating, intermeshing Coperion Werner-Pfleiderer ZSK-30 twin
screw extruder. The ZSK-30 had ten barrel sections, with an overall
length of 960 mm and an L/D ratio of 32. The extruder consisted of
a DC motor, connected to a gear box by V-belts. The 15 hp (11.2 kW)
motor was powered by a GE adjustable speed drive, located in the
control cabinet. The control range of the screw shaft speed was
1:10. The maximum extruder screw speed was 500 rpm. The extruder
itself had eight (8) heated/cooled barrel sections, along with a 30
mm spacer, which made up five temperature controlled zones. It had
a cooled only feed section, and a heated only die section, which
was held together by tie-rods and supported on the machine frame.
Each section could be heated electrically with angular half-shell
heaters, and cooled by a special system of cooling channels. The
screws consisted of continuous shafts, on which screw-flighted
components and special kneading elements were installed, in any
required order. The elements were held together radially by keys
and keyways, and axially by a screwed-in screw tip. The screw
shafts were connected to the gear-shafts by couplings, and could
easily be removed from the barrels for dismantling. The melt blends
were pelletized for GPC, DSC, melt index, density, rheology, melt
strength, and hexene extractable characterization. The compositions
are shown in Tables 8-11. Some composition properties are listed in
Tables 12-18 below. DSC profiles are shown in FIGS. 1-4. Additional
properties are discussed in Studies 1-3 below.
TABLE-US-00008 TABLE 8 Compositions (Study 1) First Second First
Second Composition Composition Composition Composition wt % wt %
Sample 1 Agility EC 7000 -- 100 -- Comp. Sample 2 Agility EC 7000
HDPE-1 85 15 Sample 3 Agility EC 7000 HDPE-6 85 15 Sample 4 Agility
EC 7000 HDPE-6 80 20 Sample 5 Agility EC 7000 HDPE-2 85 15 Sample 6
Agility EC 7000 HDPE-3 80 20
TABLE-US-00009 TABLE 9 Additional Compositions (Study 2) First
Second First Second Composition Composition Composition Composition
wt % wt % Sample 9 LDPE-1 -- 100 -- Comp. Sample 10 LDPE-1 HDPE-7
85 15 Sample 11 LDPE-1 HDPE-1 85 15 Sample 12 LDPE-1 HDPE-6 85 15
Sample 13 LDPE-1 HDPE-2 85 15
TABLE-US-00010 TABLE 10 Additional Compositions (see Study 2) First
First Second Ethylene-based Second Composition Composition Polymer
Composition wt % wt % Sample 7 LDPE-2 HDPE-2 85 15 Sample 8 LDPE-2
HDPE-3 85 15
TABLE-US-00011 TABLE 11 Additional Compositions (Study 3) ratio of
First Second I2 (2.sup.nd comp) to First Second Composition
Composition I2 (1.sup.st ethylene- Composition Component wt % wt %
based polymer) Sample 14 Agility EC -- 100 -- -- Comparative 7000
Sample 15 Agility EC HDPE 98 2 2.63 Comparative 7000 10462N Sample
16 Agility EC HDPE 85 15 2.63 7000 10462N Sample 17 Agility EC HDPE
60 40 2.63 comparative 7000 10462N Sample 18 Agility EC HDPE 20 80
2.63 Comparative 7000 10462N Sample 19 Agility EC HDPE-4 85 15 0.26
7000
TABLE-US-00012 TABLE 12 Properties of the Compositions Ratio of I2
Ratio of I2 (2.sup.nd comp) (comp) to Ratio of I2 to I2 I2 (second
(comp) to I2 Hexane Density I2 I10 (1.sup.st comp.) comp) (1.sup.st
comp.) Extractable (g/cc) (g/10 min) (g/10 min) 0.50 to 2.70 0.30
to 2.60 0.50 to 3.00 (wt %) Sample 1 0.919 3.9 46.4 -- -- -- 3.79
Comp. Sample 2 0.9246 3.0 32.7 1.10 0.70 0.78 Not measured Sample 3
0.925 3.8 38.2 2.56 0.39 0.96 Not measured Sample 4 0.9265 6.4 61.7
2.56 0.65 1.65 2.48 Sample 5 0.925 4.9 54.0 5.13 0.24 1.25 Not
measured Sample 6 0.9273 11.1 107.6 15.38 0.18 2.83 2.47 Sample 7
0.9244 5.2 53.4 4.35 0.26 1.13 2.77 Sample 8 0.9252 6.5 66.3 13.48
0.11 1.42 2.70
TABLE-US-00013 TABLE 13 Properties of the Compositions Ratio of I2
Ratio of I2 (2nd comp) (comp) Ratio of I2 to I2 to I2 (comp) to I2
Hexane Density I2 I10 (1st comp.) (2nd comp) (1st comp.)
Extractable (g/cc) (g/10 min) (g/10 min) 0.50 to 2.70 0.30 to 2.60
0.50 to 3.00 (wt %) Sample 9 0.9194 6.9 81.9 -- -- -- 3.32 Comp.
Sample 10 0.9246 4.0 41.8 0.29 2.00 0.58 2.67 Sample 11 0.924 4.9
51.4 0.62 1.14 0.71 Not measured Sample 12 0.9243 6.4 68.5 1.45
0.65 0.93 Not measured Sample 13 0.9253 7.7 76.1 2.90 0.38 1.11
2.57
TABLE-US-00014 TABLE 14 DSC Results of the Compositions Heat of
crystal- lization Tc1 Tc2 Tc3 Heat of Tm1 Tm2 Tm3 (J/g) (.degree.
C.) (.degree. C.) (.degree. C.) fusion (.degree. C.) (.degree. C.)
(.degree. C.) Sample 1 138.1 55 95 138.3 107.2 Sample 2 152.4 56.7
96.8 112.3 153.1 105.8 123.8 Sample 3 155.7 56.7 95.5 113 153.3
105.8 123.8 125.5 Sample 4 155.7 57.2 95.8 110.5 157.9 105.5 123.5
126.3 Sample 6 158.7 57.2 95 115.8 160.3 105.8 126.8 128.0 Sample 7
152.9 57.2 95.8 110.8 155.4 105.5 122.8 126.3 Sample 8 152.6 56.5
95 112 154.4 105.5 123.3 127.5
TABLE-US-00015 TABLE 15 DSC Results of the Compositions Heat of
crystal- lization Tc1 Tc2 Tc3 Heat of Tm1 Tm2 Tm3 (J/g) (.degree.
C.) (.degree. C.) (.degree. C.) fusion (.degree. C.) (.degree. C.)
(.degree. C.) Sample 9 138.7 55 95.3 139.2 107.5 Sample 10 155.2
56.7 95.5 113.5 153.7 106.0 125.0 127.8 Sample 13 153.6 56.5 95.8
110.5 156.5 105.5 122.3 126.3
TABLE-US-00016 TABLE 16 Melt Strength and DMS Properties of the
Compositions DMS at DMS at 190.degree. C. 170.degree. C. DMS DMS
Ratio of G' DMS viscosity viscosity V at (at G" = G' (at Melt
Velocity (V) at (V) at 0.1 rad/s tan tan 5 kPa, G" = strength
@break 0.1 rad/s 100 rad/s to V at delta at delta at 190.degree.
C.) 500 Pa) (cN) (mm/s) (Pa s) (Pa s) 100 rad/s 0.1 rad/s 100 rad/s
(Pa) (Pa) Sample 1 10.1 342 4873 315 15.5 3.574 0.849 3956 156
Sample 2 12.7 365 5746 426 13.5 3.391 0.980 3513 154 Sample 3 8.9
407 3484 304 11.5 4.578 1.009 3575 157 Sample 4 5.7 365 2307 297
7.8 6.917 1.136 3058 119 Sample 5 11.2 344 4648 365 12.7 3.569
0.994 3538 144 Sample 6 3.9 595 1418 213 6.7 9.217 1.186 3197 122
Sample 7 9.6 334 3246 283 11.5 4.056 1.009 3646 158 Sample 8 8.5
325 2707 246 11.0 4.348 1.023 3729 159
TABLE-US-00017 TABLE 17 Melt Strength and DMS Properties of the
Compositions DMS at DMS at 190.degree. C. 170.degree. C. DMS DMS
Ratio of DMS viscosity viscosity V at G' G' (at Melt Velocity (V)
at (V) at 0.1 rad/s tan tan (at G" = G" = strength @break 0.1 rad/s
100 rad/s to V at delta at delta at 5 KPa, 500 Pa) (cN) (mm/s) (Pa
s) (Pa s) 100 rad/s 0.1 rad/s 100 rad/s (Pa) (Pa) Sample 9 4.8 333
2419 253 9.6 6.404 0.966 3500 129 Sample 10 8.5 388 3795 386 9.8
5.015 1.026 3120 123 Sample 11 7.1 411 3031 349 8.7 5.882 1.086
3063 120 Sample 12 4.5 341 1922 261 7.4 8.262 1.142 3102 118 Sample
13 5.0 438 2046 263 7.8 7.375 1.115 3175 124
TABLE-US-00018 TABLE 18 GPC Data of the Compositions Conventional
Calibration LS Calibration using Triple Detector using Triple GPC
(except for Mw(LS-abs)/ Intrinsic Viscosity Detector GPC
Mn(cc-GPC)) and gpcBR M.sub.n,cc M.sub.w,cc M.sub.z,cc M.sub.w,cc/
M.sub.w,abs M.sub.z,abs M.sub.z,abs/ M.sub.w,abs/ IV.sub.cc
IV.sub.w gpcB IV.sub.cc/ (g/mol (g/mol) (g/mol) M.sub.n,cc (g/mol)
(g/mol) M.sub.w,abs M.sub.n,cc (dl/g) (dl/g) R IV.sub.w Sample 1
12623 120826 470549 9.57 269438 3410039 12.7 21.3 1.783 0.920 2.477
1.938 Sample 2 14259 118012 468696 8.28 249665 2934571 11.8 17.5
1.765 0.991 2.063 1.780 Sample 3 13231 111727 466288 8.44 241362
3198884 13.3 18.2 1.686 0.938 2.155 1.797 sample 4 13393 96480
454481 7.20 242443 4480334 18.5 18.1 1.517 0.888 2.330 1.708 sample
6 12422 92954 460538 7.48 241313 4758133 19.7 19.4 1.463 0.830
2.556 1.763 sample 7 13776 111091 550571 8.06 273014 3801713 13.9
19.8 1.653 0.916 2.482 1.804 sample 8 12636 111394 563063 8.82
279798 3862350 13.8 22.1 1.646 0.889 2.625 1.851 sample 9 12012
103886 480394 8.65 280797 5225538 18.6 23.4 1.585 0.836 2.923 1.896
sample 10 13516 104831 469161 7.76 266900 4645957 17.4 19.7 1.612
0.930 2.437 1.734 sample 13 13623 97329 461965 7.14 251696 4379034
17.4 18.5 1.521 0.870 2.498 1.748
Study 1--Extrusion Coating and Heat Seal Strength
[0181] The extrusion coating properties and heat seal properties
were examined for Samples 1C and 2-6. See Table 8 above. Results
are shown in Tables 19-21.
TABLE-US-00019 TABLE 19 Extrusion Coating Results (Study 1) Reduced
Horse Power Neck-in Neck-in Rate (HP) of at 440 at 880 Draw Draw
motor that MELT fpm fpm Down Down drives the Current Temperature
Pressure (inch) (inch) (fpm) (fpm) single screw (amperage) (deg.
F.) (psi) Sample 1 2.000 1.75 NB Not 22 118 601 1074 tested Sample
2 2.125 1.875 NB Not 28 126 605 1502 tested Sample 3 2.125 1.75 NB
1150 25 123 604 1300 Sample 4 2.125 1.875 NB 1243 25 128 603 1393
Sample 5 2.125 1.875 NB 1349 24 121 602 1188 Sample 6 2.125 1.875
NB 1386 23 124 600 1050 *NB = Extrudate did not break at the
maximum line speed (1500 fpm).
TABLE-US-00020 TABLE 20 Heat Seal Strength of each Composition
(Study 1) Sealing Heat Seal Strength (lbs) Mean .+-. SD (n = 5)
Temp. 80.degree. C. 90.degree. C. 100.degree. C. 110.degree. C.
120.degree. C. 130.degree. C. 140.degree. C. 150.degree. C. Sample
1 0 1.3 .+-. 0.8 3.0 .+-. 0.3 3.2 .+-. 0.4 3.2 .+-. 0.7 3.1 .+-.
0.6 3.3 .+-. 0.5 3.2 .+-. 0.6 comp. Sample 2 0 0 1.9 .+-. 0.6 2.8
.+-. 0.3 3.0 .+-. 0.2 2.9 .+-. 0.4 3.4 .+-. 0.4 3.0 .+-. 0.6 Sample
3 0 0 1.9 .+-. 0.5 2.6 .+-. 0.3 2.6 .+-. 0.4 2.4 .+-. 0.1 2.9 .+-.
0.3 3.1 .+-. 0.5 Sample 4 0 0.1 .+-. 0 1.8 .+-. 0.3 2.5 .+-. 0.2
2.3 .+-. 0.4 2.8 .+-. 0.2 3.1 .+-. 0.6 3.5 .+-. 0.4 Sample 5 0 0
1.6 .+-. 0.3 2.2 .+-. 0.2 2.3 .+-. 0.3 2.6 .+-. 0.3 2.4 .+-. 0.3
2.7 .+-. 0.2 Sample 6 0 0 0.4 .+-. 0.1 1.0 .+-. 0.3 1.2 .+-. 0.3
1.3 .+-. 0.3 1.6 .+-. 0.2 2.0 .+-. 0.2
[0182] Samples 2-6, each contain the same LDPE (AGILITY EC 7000),
and also contain a minor amount of a HDPE resin. These samples show
good extrusion coating performance (relatively low neck-in values
and relative high draw down values). However, it has been
discovered that Samples 2-4 show better "heat seal strength,"
especially at temperatures greater than, or equal to, 110.degree.
C., indicating that when the melt index (I2) ratio of the "HDPE
(the second composition)" to the "LDPE (first composition)" is from
0.50 to 2.70, a higher heat seal strength results. It is postulated
that this ratio range provides a faster inter-diffusion rate for
polymer molecules at the sealed interface during the heat seal
process. If the melt index ratio is less than, 0.50, than the drawn
down value would begin to decrease (for example, see Table 19).
Sample 1 does not have HDPE, and has a higher WVTR (worse barrier)
than the inventive Samples 2-6, as shown in Table 21.
TABLE-US-00021 TABLE 21 WVTR of each Composition Sample Sample 1
Sample 2 Sample 3 Sample 4 Sample 5 Sample 6 WVTR [g mil/ 1.81 .+-.
0.02 1.63 .+-. 0.13 1.57 .+-. 0.04 1.62 .+-. 0.11 1.47 .+-. 0.04
1.38 .+-. 0.15 (100 in.sup.2 day)] WVTR mean +/- SD
Study 2--Extrusion Coating and Heat Seal Strength
[0183] The extrusion coating properties and heat seal properties
were examined for Samples 9C and 10-13. See Table 9 above. Results
are shown in Tables 22-24.
TABLE-US-00022 TABLE 22 Reduced Horse Power Neck-in Neck-in Rate
(HP) of at 440 at 880 Draw Draw motor that MELT fpm fpm Down Down
drives the Current Temperature Pressure (inch) (inch) (fpm) (fpm)
single screw (amperage) (deg. F.) (psi) Sample 9 3.000 2.625 NB NB
21 120 599 847 Sample 10 2.625 2.25 NB 1491 27 128 601 1427 Sample
11 2.625 2.25 NB NB 25 122 602 1283 Sample 12 2.625 2.25 NB NB 23
120 600 1137 Sample 13 2.625 2.25 NB NB* 22 118 597 992 *NB =
Extrudate did not break at the maximum line speed (1500 fpm); it is
estimated that the draw down value is significantly greater than
1500 fpm.
TABLE-US-00023 TABLE 23 Sealing Heat Seal Strength (lbs) Temp.
80.degree. C. 90.degree. C. 100.degree. C. 110.degree. C.
120.degree. C. 130.degree. C. 140.degree. C. 150.degree. C. Sample
9 0 1.8 .+-. 0.8 2.6 .+-. 0.1 3.3 .+-. 0.4 3.3 .+-. 0.5 3.3 .+-.
0.5 3.7 .+-. 0.5 3.9 .+-. 0.4 Comp. Sample 10 0 0 1.7 .+-. 0.4 2.4
.+-. 0.3 2.5 .+-. 0.2 2.8 .+-. 0.3 2.8 .+-. 0.4 2.9 .+-. 0.2 Sample
11 0 0 0.7 .+-. 0.4 2.5 .+-. 0.2 2.6 .+-. 0.4 2.6 .+-. 0.2 2.9 .+-.
0.3 3.0 .+-. 0.3 Sample 12 0 0 1.8 .+-. 0.4 2.4 .+-. 0.1 2.6 .+-.
0.2 2.4 .+-. 0.6 2.9 .+-. 0.3 3.1 .+-. 0.6 Sample 13 0 0 0.8 .+-.
0.3 1.5 .+-. 0.2 1.5 .+-. 0.3 2.0 .+-. 0.2 1.9 .+-. 0.2 2.1 .+-.
0.3
[0184] Samples 10-13, each contain the same LDPE (LDPE-1), and also
contain a minor amount of a HDPE resin. All of the samples, show
good extrusion coating performance (relatively low neck-in values
and relative high draw down values). However, the draw down value
for Sample 10 is not as good as the drawn down values of Samples
11-13. Also, it has been discovered that Samples 10-12 show better
"heat seal strength," especially at temperatures greater than, or
equal to, 110.degree. C. These results indicate that when the melt
index (I2) ratio of the "HDPE (the second composition)" to the
"LDPE (first ethylene-based polymer)" is from 0.50 to 2.70 (Samples
11 and 12), a better balance of extrusion coating properties and
higher heat seal strength results. Sample 9 does not contain HDPE,
and had a higher WVTR (worse barrier) than the inventive Samples
10-13, as shown in Table 24 below.
TABLE-US-00024 TABLE 24 Sample Sample Sample Sample Sample Sample 9
10 11 12 13 WVTR 1.97 1.45 1.74 1.61 1.44 [g mil/(100 in.sup.2
day)]
[0185] Samples 7 and 8 (both contain LDPE-2, which is a blend of
AGILITY EC 7000 and LDPE-1). See Table 10 above. Each sample showed
good extrusion coating performance, with neck-in values at 440 fpm
around 2.38 inch, and reduced rate draw down values around 1480 fpm
and above.
Study 3--Extrusion Coating and WVTR
[0186] The extrusion coating properties and "water vapor
transmission rate" properties were examined for Samples 14C, 15C,
16, 17C, 18C and 19. See Table 11 above. Results are shown in
Tables 25 and 26.
TABLE-US-00025 TABLE 25 Additional Extrusion Coating Results (Study
3) Neck-in Neck-in Reduced at 440 at 880 Draw Rate Draw HP MELT fpm
fpm Down Down (horse Current Temperature Pressure (inch) (inch)
(fpm) (fpm) power) (amp) (deg. F.) (psi) Sample 14 2.000 1.875 NB
1250 22 119 601 1061 Sample 15 2.125 1.875 1174 Not tested 23 122
599 1097 Sample 16 2.000 1.875 1200 Not tested 25 125 602 1316
Sample 17 2.125 2.000 920 Not tested 29 127 603 1554 Sample 18
2.875 2.750 1423 Not tested 32 134 608 2118 Sample 19 2.125 -- 880
Not tested 30 131 609 1888
TABLE-US-00026 TABLE 26 WVTR of each Composition (Study 3) Sample
Sample 14 Sample 15 Sample 16 Sample 17 Sample 18 Sample 19 WVTR
(g/100 1.92 .+-. 0.10 1.71 .+-. 0.01 1.54 .+-. 0.22 1.13 .+-. 0.23
1.05 .+-. 0.01 1.85 .+-. 0.19 in.sup.2/day)
[0187] Samples 15-19 each contain the same LDPE (AGILITY EC 7000),
and varying amounts of HDPE. The comparative Sample 18 contains a
majority amount of the HDPE. Sample 15 contains a higher level of
LDPE, than what is preferred. As seem in Tables 25 and 26, Sample
16 shows the better balance of extrusion coating properties (low
neck-in and high drawn down) and water vapor transmission rate (low
WVTR). The comparative Samples 15, 17 and 18 have either high WVTR
value (Sample 15), or poor extrusion coating properties (e.g., high
neck-in and low draw down for Sample 17, and high neck-in for
Sample 18). It has been discovered that the inventive compositions
containing at least 65 wt % of the LDPE have a better balance of
extrusion coating properties and WVTR, as compared to the
comparative samples containing more HDPE (Sample 18) and to
comparative Sample 15, containing too much LDPE.
[0188] Compared to Sample 19, Sample 16 shows a better balance of
the above properties--see Tables 25 and 26. It has been discovered,
for this study, that when the melt index (I2) ratio of the "HDPE
(the second composition)" to the "LDPE (first composition)" is from
0.50 to 2.70, a better balance of extrusion coating properties and
lower WVTR results. It is postulated that this ratio range provides
a faster crystallization rate, which leads to a higher
crystallinity and lower WVTR. Sample 14 does not have HDPE, and has
a higher WVTR (worse barrier) than the inventive Sample 16.
* * * * *