U.S. patent application number 16/841292 was filed with the patent office on 2020-07-23 for blends of linear low density polyethylenes.
The applicant listed for this patent is Univation Technologies, LLC. Invention is credited to Nitin Borse, Swapnil B. Chandak.
Application Number | 20200231791 16/841292 |
Document ID | / |
Family ID | 62621085 |
Filed Date | 2020-07-23 |
United States Patent
Application |
20200231791 |
Kind Code |
A1 |
Chandak; Swapnil B. ; et
al. |
July 23, 2020 |
BLENDS OF LINEAR LOW DENSITY POLYETHYLENES
Abstract
A polyethylene blend comprising a uniform dispersion of
constituents (A) and (B): (A) a Ziegler-Natta catalyst-made linear
low density polyethylene and (B) a metallocene catalyst-made linear
low density polyethylene, a composition comprising the polyethylene
blend and at least one additive, methods of making and using same,
and manufactured articles and films comprising or made from
same.
Inventors: |
Chandak; Swapnil B.;
(Pearland, TX) ; Borse; Nitin; (Pearland,
TX) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Univation Technologies, LLC |
Houston |
TX |
US |
|
|
Family ID: |
62621085 |
Appl. No.: |
16/841292 |
Filed: |
April 6, 2020 |
Related U.S. Patent Documents
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Application
Number |
Filing Date |
Patent Number |
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16612072 |
Nov 8, 2019 |
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PCT/US2018/034845 |
May 29, 2018 |
|
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16841292 |
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62512865 |
May 31, 2017 |
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Current U.S.
Class: |
1/1 |
Current CPC
Class: |
C08L 2207/07 20130101;
C08J 2423/06 20130101; C08L 2203/16 20130101; C08L 2207/066
20130101; C08L 2205/025 20130101; C08J 3/203 20130101; C08L 2314/02
20130101; C08J 5/18 20130101; C08J 2323/06 20130101; C08L 23/0815
20130101; C08L 2314/06 20130101; C08L 23/0815 20130101; C08L
23/0815 20130101 |
International
Class: |
C08L 23/08 20060101
C08L023/08; C08J 5/18 20060101 C08J005/18; C08J 3/20 20060101
C08J003/20 |
Claims
1. A polyethylene blend comprising a uniform dispersion of
constituents (A) and (B): (A) a Ziegler-Natta catalyst-made linear
low density polyethylene (ZN-LLDPE) and (B) a metallocene
catalyst-made linear low density polyethylene (MCN-LLDPE); wherein
the (A) ZN-LLDPE is from 15 to 75 weight percent (wt %) of the
total weight of (A) and (B) and the (B) MCN-LLDPE is from 85 to 25
wt % of the total weight of (A) and (B); wherein by itself (A) is
independently characterized by properties (i) to (iii): (i) a melt
index ("I.sub.2", 190.degree. C., 2.16 kg) of 0.5 to 2.5 gram per
10 minutes (g/10 min.) measured according to ASTM D1238-04; (ii) a
density from 0.905 to 0.930 gram per cubic centimeter (g/cm.sup.3),
measured according to ASTM D792-13; and (iii) .eta..sub.o
detectable amount of long chain branching per 1,000 carbon atoms
("LCB Index"), measured according to LCB Test Method; and wherein
by itself (B) is independently characterized by properties (i) to
(iii): (i) a melt index ("I.sub.2", 190.degree. C., 2.16 kg) of 0.5
to 2.5 g/10 min. measured according to ASTM D1238-04; (ii) a
density from 0.905 to 0.930 g/cm.sup.3, measured according to ASTM
D792-13; and (iii) .eta..sub.o detectable amount of long chain
branching per 1,000 carbon atoms ("LCB Index"), measured according
to LCB Test Method; and with the proviso that the density of
constituent (B) is within .+-.0.003 g/cm.sup.3 of the density of
constituent (A); wherein the (A) ZN-LLDPE is made by copolymerizing
ethylene and 1-butene in the presence of the Ziegler-Natta catalyst
and the (B) MCN-LLDPE is made by copolymerizing ethylene and
1-butene in the presence of the metallocene catalyst.
2. The polyolefin blend of claim 1, further characterized by one of
limitations (i) to (vii): (i) each of ZN-LLDPE and MCN-LLDPE is
independently characterized by a melt index of ("I.sub.2",
190.degree. C., 2.16 kg) of 0.5 to 1.99 g/10 min.; (ii) the melt
index of constituent (B) is within .+-.0.4 g/10 min. of the melt
index of constituent (A); (iii) both (i) and (ii); (iv) each of the
ZN-LLDPE and MCN-LLDPE is independently characterized by a density
of 0.918.+-.0.003 g/cm.sup.3; (v) the density of constituent (B) is
within .+-.0.001 g/cm.sup.3 of the density of constituent (A); (vi)
both (iv) and (v); or (vii) both (iii) and (vi).
3. The polyolefin blend of claim 1, when formed as a film having a
thickness of 0.0127 millimeter (0.500 mil), is further
characterized by an increase in film puncture resistance, relative
to film puncture resistance of (A) or (B) alone, of from 0.50% to
50%, all when tested according to ASTM D5748-95(2012).
4. A method of making the polyolefin blend of claim 1, the method
comprising: (a) contacting discrete solid particles and/or a
discrete melt of constituent (A) with discrete solid particles
and/or a discrete melt of constituent (B) to give an initial
mixture of (A) and (B); (b) heating any solid particles of (A) and
any solid particles of (B) in the initial mixture above their
melting temperature to give a complete melt of constituents (A) and
(B); (c) blending the complete melt to an even extent to give the
polyolefin blend as a uniform melt blend of constant composition of
(A) and (B) throughout.
5. The method of claim 4, further comprising (d) cooling the
uniform melt blend to a temperature below its solidification
temperature, thereby giving the polyolefin blend as a solid of
constant composition of (A) and (B) throughout.
6. A polyolefin composition comprising the polyolefin blend of
claim 1 and at least one additive (constituent) (C) to (M): (C) a
lubricant; (D) a polymer processing aid; (E) an antioxidant; (F) a
metal deactivator; (G) an ultraviolet light-promoted degradation
inhibitor ("UV stabilizer"); (H) a slip agent; (I) a hindered amine
stabilizer; (J) an antiblock agent; (K) a colorant; (L) an antifog
agent; and (M) an antistatic agent; with the proviso that the total
amount of the at least one additive is from >0 to 5 wt % of the
polyolefin composition and the polyolefin blend is from <100 to
80 wt % of the polyolefin composition.
7. A method of making the polyolefin composition of claim 6, the
method comprising contacting the polyolefin blend with the at least
one additive (C) to (M) to give the polyolefin composition.
8. A manufactured article comprising a shaped form of the
polyolefin blend of claim 1.
9. A polyethylene film of the polyolefin blend of claim 1.
10. A method of making a polyethylene film, the method comprising
restricting in one dimension the polyethylene blend of claim 1,
thereby giving the polyethylene film.
Description
FIELD
[0001] The field includes linear low density polyethylene blends
and compositions containing same, methods of making and using same,
and manufactured articles and films.
INTRODUCTION
[0002] A linear low density polyethylene ("LLDPE") is a
substantially linear macromolecule composed of ethylene monomeric
units and alpha-olefin comonomeric units. The typical comonomeric
units used in commerce are derived from 1-butene, 1-hexene, or
1-octene. A LLDPE may be distinguished from a conventional low
density polyethylene ("LDPE") any number of ways. Their respective
manufacturing processes are different. LLDPE has substantially no
detectable long chain branching per 1,000 carbon atoms, whereas
conventional LDPE contains long chain branching. LLDPE has a
narrower molecular weight distribution (MWD) relative to MWD of
LDPE. LLDPE has different respective rheological and mechanical
properties such as tensile strength or film puncture
resistance.
[0003] US 2014/0179873 A1 to P. Lam, et al. (LAM) relates to a
polymer blend comprising first and second polyethylene copolymers.
The blend may be made into a film.
[0004] KR 2016062727A and KR2014002351A relate to polyethylenes and
films.
SUMMARY
[0005] We recognized a problem that hurts the manufacturing and
performance of prior LLDPE films. The films may have deficient film
puncture resistance. They may also have deficient tear strength
and/or tensile yield strength in the machine direction (MD) and/or
cross direction (CD).
[0006] A technical solution to this problem was not obvious. Past
attempts to improve (increase) film puncture resistance of
polyethylene films failed or worsened (decreased) dart impact or
modulus. A problem to be solved then is to discover an LLDPE film
that has improved (increased) film puncture resistance, preferably
without worsening dart impact and/or modulus.
[0007] Our technical solution to this problem includes a
polyethylene blend (inventive blend) comprising a uniform
dispersion of constituents (A) and (B): (A) a Ziegler-Natta
catalyst-made linear low density polyethylene (ZN-LLDPE) and (B) a
metallocene catalyst-made linear low density polyethylene
(MCN-LLDPE). We discovered that when the ZN-LLDPE has a first
combination of properties and the MCN-LLDPE has a second
combination of properties, and the ZN-LLDPE and MCN-LLDPE are
uniformly mixed together in certain relative amounts, the result is
a blend that has enhanced (increased) puncture resistance relative
to puncture resistance that would be expected for the blend based
on puncture resistance of comparative films composed of the
ZN-LLDPE alone or the MCN-LLDPE alone. Also inventive are a
polyethylene composition comprising the inventive blend and at
least one additive that is not (A) or (B) (inventive composition),
a method of making the blend, a method of shaping the blend into an
article, and a manufactured article composed of or made from the
blend or composition.
DETAILED DESCRIPTION
[0008] The Summary and Abstract are incorporated here by
reference.
[0009] The "enhanced puncture resistance" for the inventive blend
is described relative to puncture resistance of a first comparative
film composed of the (A) ZN-LLDPE alone (100 wt % ZN-LLDPE/0 wt %
MCN-LLDPE film) and puncture resistance of a second comparative
film composed of the (B) MCN-LLDPE alone (0 wt % ZN-LLDPE/100 wt %
MCN-LLDPE film). Measure puncture resistance of comparative and
inventive films according to ASTM D5748-95(2012). Express puncture
resistance values in Joules per cubic centimeter (J/cm.sup.3).
1.000 J/cm.sup.3=12.09 foot-pounds-force per cubic inch
(ft*lbf/in.sup.3) and conversely 1.000 ft*lbf/in.sup.3=0.08274
J/cm.sup.3. For comparison, use a film having a thickness of 0.0127
millimeter (mm, 0.500 mil) thick film. Alternatively films of other
thickness may be compared, such as 0.0254 mm (1.00 mil), 0.0381 mm
(1.50 mil), 0.0508 mm (2.00 mils), or 0.0635 mm (2.50 mils). Plot
the puncture resistance values for the first and second comparative
films on a y-axis versus their respective weight fraction
concentrations on an x-axis. Draw a comparative trend line
(straight) from the puncture resistance value for the first
comparative film (100 wt % ZN-LLDPE/0 wt % MCN-LLDPE) to the
puncture resistance value for the second comparative film (0 wt %
ZN-LLDPE/100 wt % MCN-LLDPE). Then plot the puncture resistance
values for the blends of (A) ZN-LLDPE and (B) MCN-LLDPE. Absence
any enhancement, puncture resistance values for the blends (e.g.,
75 wt % ZN-LLDPE/25 wt % MCN-LLDPE, 50 wt % ZN-LLDPE/50 wt %
MCN-LLDPE, and 25 wt % ZN-LLDPE/75 wt % MCN-LLDPE) would be
expected to fall on the comparative trend line.
[0010] Unpredictably, however, the puncture resistance values for
the inventive blend are above the comparative trend line. Thus, the
inventive blend has "enhanced puncture resistance". The extent of
enhancement, indicated by the distance above the comparative trend
line, may be expressed as an absolute puncture resistance value in
J/cm.sup.3, alternatively by a percentage increase above the
comparative trend line. If a puncture resistance value for any
particular embodiment of a polyethylene blend lies on or below its
comparative trend line, that particular embodiment is not included
herein.
[0011] In some aspects the inventive blend embodiments fall within
a weight fraction concentration range wherein the (A) ZN-LLDPE is
from 15 to 75 weight percent (wt %) of the total weight of (A) and
(B) and the (B) MCN-LLDPE is from 85 to 25 wt % of the total weight
of (A) and (B). Embodiments of the inventive blend are not
restricted to those weight fraction concentration ranges, however,
provided that they are characterized by puncture resistance values
that are above their respective comparative trend lines.
[0012] Certain inventive embodiments are described below as
numbered aspects for easy cross-referencing. Additional embodiments
are described herein.
[0013] Aspect 1. A polyethylene blend comprising a uniform
dispersion of constituents (A) and (B): (A) a Ziegler-Natta
catalyst-made linear low density polyethylene (ZN-LLDPE) and (B) a
metallocene catalyst-made linear low density polyethylene
(MCN-LLDPE); wherein the (A) ZN-LLDPE is from 15 to 75 weight
percent (wt %) of the total weight of (A) and (B) and the (B)
MCN-LLDPE is from 85 to 25 wt % of the total weight of (A) and (B);
wherein by itself (A) is independently characterized by properties
(i) to (iii): (i) a melt index ("I.sub.2", 190.degree. C., 2.16 kg)
of 0.5 to 2.5 gram per 10 minutes (g/10 min.) measured according to
ASTM D1238-04; (ii) a density from 0.905 to 0.930 gram per cubic
centimeter (g/cm.sup.3), measured according to ASTM D792-13; and
(iii) no detectable amount of long chain branching per 1,000 carbon
atoms ("LCB Index"), measured according to LCB Test Method
(described later); and wherein by itself (B) is independently
characterized by properties (i) to (iii): (i) a melt index
("I.sub.2", 190.degree. C., 2.16 kg) of 0.5 to 2.5 g/10 min.
measured according to ASTM D1238-04; (ii) a density from 0.905 to
0.930 g/cm.sup.3, measured according to ASTM D792-13; and (iii) no
detectable amount of long chain branching per 1,000 carbon atoms
("LCB Index"), measured according to LCB Test Method (described
later); and with the proviso that the density of constituent (B) is
within .+-.0.003 g/cm.sup.3, alternatively .+-.0.002 g/cm.sup.3,
alternatively .+-.0.001 g/cm.sup.3 of the density of constituent
(A).
[0014] Aspect 2. The polyolefin blend of aspect 1, further
characterized by one of limitations (i) to (vii): (i) each of
ZN-LLDPE and MCN-LLDPE is independently characterized by a melt
index of ("I.sub.2", 190.degree. C., 2.16 kg) of 0.5 to 1.99 g/10
min.; (ii) the melt index of constituent (B) is within .+-.0.4 g/10
min. of the melt index of constituent (A); (iii) both (i) and (ii);
(iv) each of the ZN-LLDPE and MCN-LLDPE is independently
characterized by a density of 0.918.+-.0.003 g/cm.sup.3; (v) the
density of constituent (B) is within .+-.0.001 g/cm.sup.3 of the
density of constituent (A); (vi) both (iv) and (v); or (vii) both
(iii) and (vi).
[0015] Aspect 3. The polyolefin blend of aspect 1 or 2, when formed
as a film having a thickness of 0.0127 millimeter (0.500 mil), is
further characterized by an increase in film puncture resistance,
relative to film puncture resistance of (A) or (B) alone, of from
0.50% to 50%, alternatively from 1.0% to 49%, alternatively from 5%
to 45%, all when tested according to ASTM D5748-95(2012).
[0016] Aspect 4. A method of making the polyolefin blend of any one
of aspects 1 to 3, the method comprising: (a) contacting discrete
solid particles and/or a discrete melt of constituent (A) with
discrete solid particles and/or a discrete melt of constituent (B)
to give an initial mixture of (A) and (B); (b) heating any solid
particles of (A) and any solid particles of (B) in the initial
mixture above their melting temperature to give a complete melt of
constituents (A) and (B); (c) blending the complete melt to an even
extent to give the polyolefin blend as a uniform melt blend of
constant composition of (A) and (B) throughout. If the initial
mixture does not contain any solid particles of (A) and/or (B),
then step (b) is unnecessary and may be omitted if desired. The
expression "discrete solid particles and/or a discrete melt" means
discrete solid particles, a discrete melt, or a combination
thereof. E.g., see Blend and Film Preparation Method 1 later.
[0017] Aspect 5. The method of aspect 4, further comprising (d)
cooling the uniform melt blend to a temperature below its
solidification temperature, thereby giving the polyolefin blend as
a solid of constant composition of (A) and (B) throughout.
[0018] Aspect 6. A polyolefin composition comprising the polyolefin
blend of any one of aspects 1 to 3, or the polyolefin blend made by
the method of aspect 4 or 5, and at least one additive
(constituent) (C) to (M): (C) a lubricant; (D) a polymer processing
aid; (E) an antioxidant; (F) a metal deactivator; (G) an
ultraviolet light-promoted degradation inhibitor ("UV stabilizer");
(H) a slip agent; (I) a hindered amine stabilizer; (J) an antiblock
agent; (K) a colorant; (L) an antifog agent; and (M) an antistatic
agent; with the proviso that the total amount of the at least one
additive is from >0 to 5 wt % of the polyolefin composition and
the polyolefin blend is from <100 to 80 wt % of the polyolefin
composition.
[0019] Aspect 7. A method of making the polyolefin composition of
aspect 6, the method comprising contacting the polyolefin blend
with the at least one additive (C) to (M) to give the polyolefin
composition.
[0020] Aspect 8. A manufactured article comprising a shaped form of
the polyolefin blend of any one of aspects 1 to 3, the polyolefin
blend made by the method of aspect 4 or 5, or the polyolefin
composition of aspect 6.
[0021] Aspect 9. A polyethylene film of the polyolefin blend of any
one of aspects 1 to 3 or the polyolefin blend made by the method of
aspect 4 or 5.
[0022] Aspect 10. A method of making a polyethylene film, the
method comprising restricting in one dimension the polyethylene
blend of any one of aspects 1 to 3 or the polyethylene blend made
by the method of aspect 4 or 5 or the polyolefin composition of
aspect 6, thereby giving the polyethylene film. E.g., see Blend and
Film Preparation Method 1 later.
[0023] All properties described herein are measured according to
their respective standard test methods described later unless
explicitly indicated otherwise. Density is measured according to
ASTM D792-13. Melt index (I.sub.2) is measured according to ASTM
D1238-04 (190.degree. C., 2.16 kg).
[0024] Polyolefin blend. The polyolefin blend comprises a uniform
dispersion of constituents (A) and (B). The term "uniform
dispersion" refers to the constituents (A) and (B) as being mixed
or blended together to an even extent, such that the resulting
material is of constant composition of (A) and (B) throughout. The
uniform dispersion of (A) and (B) may be liquid (melt) or a solid.
The uniform dispersion may further contain a product of a reaction
of some of (A) with some of (B) so as to form product (A)-(B).
[0025] In the polyolefin blend, the relative amount of (A) may be
in the range of from 12 to 79 wt % and (B) in the range from 88 to
21 wt %, alternatively (A) may be in the range of from 14 to 76 wt
% and (B) in the range from 86 to 24 wt %, alternatively (A) may be
in the range of from 25 to 75 wt % and (B) in the range from 75 to
25 wt %; all based on total weight of (A) and (B).
[0026] In the polyolefin blend, the uniform dispersion of (A) and
(B) is characterized by its own properties, which are different
than such properties of (A) or (B) alone, or of a mixture of
discrete particles of (A) and discrete particles of (B), such as a
blend of pellets of (A) and pellets of (B). The inventive blend may
include at least one enhanced property, relative to that of (A) or
(B) alone, that includes (i) film puncture resistance. An optional
additional enhancement may include at least one, alternatively at
least two properties (ii) to (iii): (ii) tear strength, and (iii)
tensile yield strength. Optionally the enhanced at least one
property further may include dart impact and/or modulus. An
optional additional enhancement may include at least one optical
property selected from enhanced (increased) optical clarity
(Zebedee clarity), enhanced (increased) gloss, and enhanced
(decreased) haze.
[0027] In some aspects the polyolefin blend is independently
further characterized by one of limitations (iv) to (vi): (iv) a
normal comonomer distribution measured according to Gel Permeation
Chromatography (GPC) Test Method (described later).
[0028] As an alternative or addition to the foregoing properties,
the polyolefin blend may be characterized by its chemical
composition, chemical composition distribution (CCD), density, melt
viscosity (.eta.), melt index (I.sub.2, 190.degree. C., 2.16 kg),
melting transition temperature(s), molecular weight distribution
(MWD=M.sub.w/M.sub.n), number average molecular weight (M.sub.n),
weight average molecular weight (M.sub.w), or a combination of any
two or more thereof.
[0029] The polyolefin blend may have an atomic chemical composition
that consists essentially of, alternatively consists of C, H, and
remainders of the Ziegler-Natta and metallocene catalysts. The
atomic chemical composition of the Ziegler-Natta catalyst remainder
may consist essentially of, alternatively consist of Ti, Mg, and
Cl. The atomic chemical composition of the metallocene catalyst
remainder may consist essentially of, alternatively consist of a
Group 4 metal (e.g., Ti, Zr, or Hf), C, H, and, optionally, Cl, O,
and/or N.
[0030] The polyolefin blend may have a density from 0.915 to 0.926
g/cm.sup.3, alternatively 0.920 to 0.926 g/cm.sup.3, alternatively
0.918.+-.0.003 g/cm.sup.3, alternatively 0.918.+-.0.002 g/cm.sup.3,
alternatively 0.918.+-.0.001 g/cm.sup.3, alternatively 0.918
g/cm.sup.3, all measured according to ASTM D792-13.
[0031] The polyolefin blend may have a melt index I.sub.2 from 0.5
to 2.04 g/10 min., alternatively from 0.5 to 1.99 g/10 min.,
alternatively from 0.6 to 1.4 g/10 min., alternatively from 0.9 to
1.1 g/10 min., all measured according to ASTM D1238-04. The melt
index of constituent (B) may be within .+-.0.3 g/10 min.,
alternatively within .+-.0.2 g/10 min., alternatively within
.+-.0.1 g/10 min., of the melt index of constituent (A).
[0032] The polyolefin blend may have no detectable amount of long
chain branching per 1,000 carbon atoms ("LCB Index"), measured
according to LCB Test Method (described later). The polyolefin
blend may be characterized by film puncture resistance described
later.
[0033] The polyolefin blend may be characterized by at least one of
properties (ii) to (iii): (ii) tear strength (MD or CD) from 10 to
1,000 grams per 25 micrometers (g/25 .mu.m), alternatively 20 to
900 g/25 .mu.m, alternatively 50 to 500 g/25 .mu.m, and (iii)
tensile yield strength (MD or CD) from 5 to 15 megapascals (MPa),
alternatively 6 to 14 MPa, alternatively 7 to 13 MPa. The
properties may also include dart impact from 0 to 2,000 grams (g),
alternatively 1 to 1,500 g, alternatively 5 to 1,000 g and/or
modulus from 100 to 400 MPa.
[0034] Alternatively or additionally, the polyolefin blend may be
characterized by characteristics of constituent (A), constituent
(B), or both (A) and (B) prior to being blended. Prior to blending,
each of (A) and (B) independently may be characterized by its
chemical composition, CCD, density, melt viscosity (.eta.), melt
index (I.sub.2, 190.degree. C., 2.16 kg), melting transition
temperature, MWD (M.sub.w/M.sub.n), M.sub.n, M.sub.w, or a
combination of any two or more thereof. The constituents (A) and
(B) of the polyolefin blend are composed of macromolecules. The
macromolecules of (A), (B), or both (A) and (B) independently may
consist of carbon and hydrogen atoms. As such the macromolecules
(A) and/or (B) independently may be free of other heteroatoms
(e.g., halogen, N, O, S, Si, and P). In some aspects (A) and (B)
are independently characterized by their melt indexes (I.sub.2,
190.degree. C., 2.16 kg) and densities described later. For
example, in some aspects (A) has a melt index (I.sub.2, 190.degree.
C., 2.16 kg) from 0.5 to 1.99 g/10 min. and (B) has a melt index
(I.sub.2, 190.degree. C., 2.16 kg) from 0.5 to 2.04 g/10 min.;
alternatively (B) has a melt index (I.sub.2, 190.degree. C., 2.16
kg) from 0.5 to 1.99 g/10 min. and (A) has a melt index (I.sub.2,
190.degree. C., 2.16 kg) from 0.5 to 2.04 g/10 min.; alternatively
both (A) and (B) each have a melt index (I.sub.2, 190.degree. C.,
2.16 kg) from 0.5 to 1.99 g/10 min.
[0035] Constituent (A): Ziegler-Natta catalyst-made linear low
density polyethylene (ZN-LLDPE). The ZN-LLDPE is manufactured by
copolymerizing ethylene and an alpha-olefin comonomer in the
presence of a Ziegler-Natta catalyst such as TiCl.sub.4 disposed on
a particulate MgCl.sub.2 support. Ziegler-Natta catalysts are well
known and include the Ziegler-Natta catalyst components and systems
at column 12, lines 13 to 49; column 12, line 58, to column 13,
line 25; and the cocatalysts at column 13, line 31 to column 14,
line 28, of U.S. Pat. No. 7,122,607 B2 to Robert O. Hagerty, et al.
The copolymerization process is generally well known and may be a
slurry phase, solution phase, or gas phase process. For example a
suitable gas phase process is at column 25, line 59, to column 26,
line 21, and column 33, line 32, to column 35, line 56, of U.S.
Pat. No. 7,122,607 B2.
[0036] The alpha-olefin comonomer used to make (A) may be a
(C.sub.3-C.sub.20)alpha-olefin, alternatively a
(C.sub.11-C.sub.20)alpha-olefin, alternatively a (C.sub.3 to
C.sub.10)alpha-olefin, alternatively a
(C.sub.4-C.sub.8)alpha-olefin, alternatively 1-butene or 1-hexene,
alternatively 1-butene, alternatively 1-hexene, alternatively
1-octene. (A) may be characterized by its monomer content (i.e.,
ethylene monomeric content) and comonomer content (i.e.,
alpha-olefin comonomeric content). The alpha-olefin comonomeric
units of (A) may be 1-butene comonomeric units, alternatively
1-hexene comonomeric units, alternatively 1-octene comonomeric
units.
[0037] (A) may have a density from 0.905 to 0.930 g/cm.sup.3,
alternatively 0.915 to 0.926 g/cm.sup.3, alternatively 0.920 to
0.926 g/cm.sup.3, alternatively 0.918.+-.0.003 g/cm.sup.3,
alternatively 0.918.+-.0.002 g/cm.sup.3, alternatively
0.918.+-.0.001 g/cm.sup.3, alternatively 0.918 g/cm.sup.3, all
measured according to ASTM D792-13. (A) may have a melt index
I.sub.2 from 0.5 to 2.5 g/10 min., alternatively from 0.5 to 2.04
g/10 min., alternatively from 0.5 to 1.99 g/10 min., alternatively
from 0.6 to 1.4 g/10 min., alternatively from 0.9 to 1.1 g/10 min.,
all measured according to ASTM D1238-04. (A) may have M.sub.w from
1,000 to 1,000,000 grams per mole (g/mol), alternatively from
10,000 to 500,000 g/mol, alternatively from 20,000 to 200,000
g/mol. (B) may have MWD (M.sub.w/M.sub.n) from 3.0 to 25,
alternatively from 4 to 20, alternatively from 5 to 10.
[0038] Examples of (A) are commercially available and include DOW
LLDPE DFDA 7047NT 7; Formosa Plastics FORMOLENE L42022B; Westlake
Chemical Corporation's HIFOR LF1021 and NOVAPOL TD-9022; and
Chevron Phillips' MARFLEX 7109 Polyethylene.
[0039] Constituent (B): metallocene catalyst-made linear low
density polyethylene (MCN-LLDPE). The MCN-LLDPE is manufactured by
copolymerizing ethylene and an alpha-olefin comonomer in the
presence of a metallocene catalyst such as zirconocene. Metallocene
catalysts are well known and include the metallocene catalyst
components and systems at column 14, line 30, to column 20, line
67; and the activators and activator methods at column 21, line 1
to column 25, line 57, of U.S. Pat. No. 7,122,607 B2. The
copolymerization process is generally well known and may be a
slurry phase, solution phase, or gas phase process. For example a
suitable gas phase process is at column 25, line 59, to column 26,
line 21, and column 33, line 32, to column 35, line 56, of U.S.
Pat. No. 7,122,607 B2.
[0040] The alpha-olefin comonomer used to make (B) may be a
(C.sub.3-C.sub.20)alpha-olefin, alternatively a
(C.sub.11-C.sub.20)alpha-olefin, alternatively a (C.sub.3 to
C.sub.10)alpha-olefin, alternatively a
(C.sub.4-C.sub.8)alpha-olefin, alternatively 1-butene or 1-hexene,
alternatively 1-butene, alternatively 1-hexene, alternatively
1-octene. (B) may be characterized by its monomer content (i.e.,
ethylene monomeric content) and comonomer content (i.e.,
alpha-olefin comonomeric content). The alpha-olefin comonomeric
units of (B) may be 1-butene comonomeric units, alternatively
1-hexene comonomeric units, alternatively 1-octene comonomeric
units. The alpha-olefin comonomer used to make (B) may the same as,
alternatively is different than the alpha-olefin used to make
(A).
[0041] (B) may be characterized by the molecular catalyst used to
make it. The molecular catalyst may be a metallocene, alternatively
a zirconocene, alternatively a constrained geometry catalyst.
[0042] (B) may have a density from 0.905 to 0.930 g/cm.sup.3,
alternatively 0.915 to 0.926 g/cm.sup.3, alternatively 0.920 to
0.926 g/cm.sup.3, alternatively 0.918.+-.0.003 g/cm.sup.3,
alternatively 0.918.+-.0.002 g/cm.sup.3, alternatively
0.918.+-.0.001 g/cm.sup.3, alternatively 0.918 g/cm.sup.3, all
measured according to ASTM D792-13. (B) may have a melt index
I.sub.2 from 0.5 to 2.5 g/10 min., alternatively from 0.5 to 2.04
g/10 min., alternatively from 0.5 to 1.99 g/10 min., alternatively
from 0.6 to 1.4 g/10 min., alternatively from 0.9 to 1.1 g/10 min.,
all measured according to ASTM D1238-04. (B) may have M.sub.w from
1,000 to 1,000,000 g/mol, alternatively from 10,000 to 500,000
g/mol, alternatively from 20,000 to 200,000 g/mol. (B) may have MWD
(M.sub.w/M.sub.n) from >2.00 to 3.0, alternatively from 2.01 to
2.9, alternatively from 2.1 to 2.5.
[0043] Examples of (B) are commercially available and include
ExxonMobil EXCEED 1018HA, Ineos ELTEX PF6012AA; Chevron Phillips'
MARFLEX D170Dk Polyethylene; Sabic's SUPEER 8118(L) mLLDPE; and
TOTAL's Polyethylene LUMICENE M 1810 EP.
[0044] Polyolefin composition. The polyolefin composition comprises
the polyolefin blend and the at least one additive, such as
additive (C) to (M) described earlier. The inventive composition
independently may, alternatively may not have a constant
composition of the inventive blend and/or the at least one additive
throughout. In some aspects the polyolefin composition comprises at
least one of the (C) lubricant. Suitable lubricants are carbowax
and metal stearates, (D) polymer processing aid (e.g., Dunamar FX),
(E) antioxidant such as a primary antioxidant or a combination of
primary and secondary antioxidants, (F) metal deactivator, (G) UV
stabilizer (e.g., silica or carbon black), and (H) slip agent, (I)
hindered amine stabilizer, (J) antiblock agent, (K) colorant, (L)
antifog agent, and (M) antistatic agent. A suitable amount of each
of the additives may be from >0 to 5 weight percent (wt %),
alternatively 0.5 to 5 wt %, alternatively 1 to 2 wt %. The total
weight of all constituents, including additives, in the polyolefin
composition is 100.00 wt %.
[0045] The polyolefin blend and polyolefin composition may be
substantially free of, alternatively may not contain, a polyolefin
other than constituents (A) and (B). E.g., may be substantially
free from or, alternatively does not contain, a conventional low
density polyethylene (LDPE), a medium density polyethylene (MDPE),
a high density polyethylene (HDPE), a poly(alpha-olefin), an
ethylene/unsaturated carboxylic ester copolymer, a
polyorganosiloxane, a poly(alkylene glycol), or a polystyrene.
[0046] The polyolefin composition may be made by any suitable
method provided that (A) and (B) are blended together to give the
polyolefin blend. The (A) and (B) may be blended together as
described herein before being contacted with any additive. That is,
the polyolefin blend containing the uniform mixture of (A) and (B)
may be made, and then later the uniform mixture may be contacted
with any optional additive (C) to (L). Alternatively, the (A) and
(B) may be blended together as described herein in the presence of
one or more optional additives (C) to (L), if any, to give an
embodiment of the polyolefin blend further containing the one or
more additives. Typically for (C), the polyolefin blend is made,
and then the (C) organic peroxide is added to the polyolefin blend
to give the polyolefin composition.
[0047] To facilitate mixing of a preformed polyolefin blend of
constituents (A) and (B) with the additive(s), the additive(s) may
be provided in the form of an additive masterbatch, i.e., a
dispersion of additive(s) in a carrier resin. Before making the
preformed polyolefin blend, some of (A) or (B), or afterwards some
of the preformed polyolefin blend of (A) and (B), may be set aside
for use as the carrier resin.
[0048] Method of making the polyethylene blend. "Discrete solid
particles and/or a discrete melt" means discrete solid particles, a
discrete melt, or a combination thereof. In some aspects step (a)
comprises dry blending discrete solid particles consisting
essentially of, alternatively consisting of (A) with discrete solid
particles consisting essentially of, alternatively consisting of
(B) to give an aspect of the initial mixture consisting essentially
of, alternatively consisting of solid particles of (A) and solid
particles of (B). As used above "consisting essentially of" means
one or more additives (C) to (L) may be present, but other
polyolefins are absent. In some aspects step (a) comprises melt
blending a melt consisting essentially of, alternatively consisting
of (A) with a melt consisting essentially of, alternatively
consisting of (B) to give an aspect of the initial mixture
consisting essentially of, alternatively consisting of a melt of
(A) and a melt of (B). In some aspects step (a) is a combination of
both of the foregoing aspects. The amount of (A) and the amount of
(B) used in the method may be measured and selected so as to give
an aspect of the polyethylene blend having a specific wt % of (A)
in the range of from 15 to 75 wt % and a specific wt % of (B) in
the range from 85 to 25 wt %, based on total weight of (A) and (B),
or each in any one of the alternative ranges thereof described
earlier.
[0049] In the method of making the polyethylene blend, in some
aspects step (b) comprises heating an aspect of the initial mixture
of step (a) containing solid particles of (A) having a first
melting temperature and/or heating solid particles of (B) having a
second melting temperature above the highest one of the first and
second melting temperatures to give the complete melt of (A) and
(B). The aspect of the initial mixture may also contain,
alternatively may not contain a partial melt of (A) and/or a
partial melt of (B). In some aspects step (b) heating is performed
in an extruder such as a single screw or twin screw extruder
configured with a heating device.
[0050] In some aspects step (b) of the method of making the
polyethylene blend is unnecessary if step (a) comprises the melt
blending a melt consisting essentially of, alternatively consisting
of (A) with a melt consisting essentially of, alternatively
consisting of (B) to give an aspect of the initial mixture
consisting essentially of, alternatively consisting of a melt of
(A) and a melt of (B). In the latter aspects the initial mixture of
step (a) is free of solid particles of (A) and (B).
[0051] In the method of making the polyethylene blend, in some
aspects step (c) comprises using the extruder (e.g., the single
screw or twin screw extruder) to blend the complete melt of step
(b) to an even extent to give the polyolefin blend as a uniform
melt blend of constant composition of (A) and (B) throughout.
[0052] In the method of making the polyethylene blend, in some
aspects step (d) comprises passive cooling (natural cooling without
using energy), alternatively active cooling (using energy to remove
heat) of the uniform melt blend to a temperature below its
solidification temperature, thereby giving the polyolefin blend as
a solid uniform dispersion of constant composition of (A) and (B)
throughout. The cooling may be performed at a controlled rate
during the temperature range in which the polyethylene blend or its
constituents (A) and (B) solidify, thereby controlling the
morphology of the solidified polyethylene blend.
[0053] The polyethylene film. In some aspects the polyethylene film
has a thickness from 0.0102 to 0.254 mm (0.400 mil to 10 mils),
alternatively from 0.01143 mm to 0.254 mm (0.450 mil to 10 mils),
alternatively from 0.01143 mm to 0.127 mm (0.450 mil to 5.00 mils),
alternatively from 0.01143 mm to 0.0762 mm (0.450 mil to 3.00
mils), alternatively from 0.0127 mm to 0.0635 mm (0.500 mil to 2.50
mils). In some aspects the polyethylene film is made as an aspect
of the method of making the polyethylene blend or composition. In
such aspects the polyethylene film may be made after step (c)
blending and before step (d) cooling, both of the method of making
the polyethylene blend or composition. In some such aspects the
polyethylene film is made by a method that comprises: (a) dry
blending discrete solid particles consisting essentially of,
alternatively consisting of (A) with discrete solid particles
consisting essentially of, alternatively consisting of (B) to give
an aspect of the initial mixture consisting essentially of,
alternatively consisting of solid particles of (A) and solid
particles of (B); (b) heating the initial mixture to give the
complete melt of constituents (A) and (B); (c) blending the
complete melt to an even extent to give the polyolefin blend as a
uniform melt blend of constant composition of (A) and (B)
throughout; (d) blowing the uniform melt blend so as to form a film
and cool same to give the polyolefin blend as a polyethylene film
aspect of the manufactured article.
[0054] The polyethylene film may be made using any blown-film-line
machine configured for making polyethylene films. The machine may
be configured with a feed hopper in fluid communication with an
extruder in heating communication with a heating device capable of
heating a polyethylene in the extruder to a temperature of up to
500.degree. C. (e.g., 430.degree. C.), and wherein the extruder is
in fluid communication with a die having an inner diameter of 20.3
centimeters (8 inches) and a fixed die gap (e.g., 1.778 millimeter
gap (70 mils)), a blow up ratio of 2.5:1, and a Frost Line Height
(FLH) of 76.+-.10 centimeters (30.+-.4 inches) from the die. Step
(a) may be done in the feed hopper. Steps (b) and (c) may be done
in the extruder and at a temperature of 400.degree. to 450.degree.
C. (e.g., 430.degree. C.). Step (d) may be done in the die and
after exiting the die. The machine may have capacity of a feed rate
of (A) and (B), and production rate of film, from 50 to 200
kilograms (kg) per hour, e.g., 91 kg (201 pounds) per hour at
430.degree. C.
[0055] The polyethylene film is useful for making containers and
wraps that have enhanced puncture resistance. Examples of such
containers are bags such as ice bags and grocery bags. Examples of
such wraps are stretch films, meat wraps, and food wraps. The
inventive blend and composition are also useful in a variety of
non-film related applications including in vehicle parts.
[0056] Advantageously we discovered that the polyolefin blend and
polyolefin composition have improved (increased) (i) film puncture
resistance relative to that of constituent (A) alone and
constituent (B) alone. In some aspects the puncture resistance,
measured according to ASTM D5748-95(2012) using a film having a
thickness of 0.0127 millimeter (0.500 mil), is at least 21.41
Joules per cubic centimeter (J/cm.sup.3), alternatively at least
21.9 J/cm.sup.3, alternatively at least 24.8 J/cm.sup.3,
alternatively at least 28 J/cm.sup.3. In some such aspects the
puncture resistance may be at most 40 J/cm.sup.3, alternatively at
most 35 J/cm.sup.3, alternatively at most 33 J/cm.sup.3,
alternatively at most 31 J/cm.sup.3, alternatively at most 30.5
J/cm.sup.3. In some aspects the enhancement of puncture resistance
using a film having a thickness of 0.0127 millimeter (0.500 mil) is
from 0.10 to 10 J/cm.sup.3, alternatively from 1.0 to 10.0
J/cm.sup.3, alternatively from 3 to 9.4 J/cm.sup.3, all when tested
according to ASTM D5748-95(2012), relative to expected puncture
resistance values at the same weight fraction concentration as
derived from a comparative trend line for actual comparative
puncture resistance values at 100% ZN-LLDPE and 100 wt % MCN-LLDPE.
In some aspects the enhancement of puncture resistance using a film
having a thickness of 0.0127 millimeter (0.500 mil) is from 0.60%
to 50%, alternatively from 1.0% to 49%, alternatively from 5% to
45%, all when tested according to ASTM D5748-95(2012), relative to
expected puncture resistance values at the same weight fraction
concentration as derived from a comparative trend line for actual
comparative puncture resistance values at 100% ZN-LLDPE and 100 wt
% MCN-LLDPE. In some aspects the polyolefin blend is characterized
by, and a greater puncture resistance enhancement is obtained with,
constituents (A) and (B) wherein the melt index ("I.sub.2",
190.degree. C., 2.16 kg) of constituent (B) is within .+-.0.4 g/10
min., alternatively .+-.0.2 g/10 min., alternatively .+-.0.1 g/10
min. of the melt index ("I.sub.2", 190.degree. C., 2.16 kg) of
constituent (A).
[0057] In some aspects the film of the polyolefin blend is
characterized by a combination of composition, properties and
characteristics that may give extra enhancement of puncture
resistance. In some such aspects the blend is composed of (A)
having 1-butene comonomeric units and a melt index value of
1.0.+-.0.1 g/10 min. and (B) having a melt index value of
1.0.+-.0.1 g/10 min. The melt index values are ("I.sub.2",
190.degree. C., 2.16 kg) measured according to ASTM D1238-04. In
some such embodiments, the film may have a thickness of 0.0127 mm
(0.5 mil) and weight fractions of (A) and (B) in a range from 50 wt
% (A)/50 wt % (B) to 25 wt % (A)/75 wt % (B). In other such aspects
the film may have a thickness of 0.0381 mm (1.5 mil); and weight
fractions of (A) and (B) in a range from 45 wt % (A)/55 wt % (B) to
55 wt % (A)/45 wt % (B). In some such embodiments, the film may
have a thickness in the range of from 0.0127 to 0.0381 mm (0.5 to
1.5 mil).
[0058] In some such aspects the blend is composed of (A) having
1-butene comonomeric units and a melt index value of 2.0.+-.0.1
g/10 min. and (B) having a melt index value of 1.0.+-.0.1 g/10 min.
The melt index values are ("I.sub.2", 190.degree. C., 2.16 kg)
measured according to ASTM D1238-04. In some such embodiments, the
film may have a thickness of 0.0127 mm (0.5 mil); and weight
fractions of 50.+-.10 wt %, alternatively 50.+-.5 wt %,
alternatively 50.+-.1 wt % of (A) and 50.+-.10 wt %, alternatively
50.+-.5 wt %, alternatively 50.+-.1 wt % of (B).
[0059] In some such aspects the blend is composed of (A) having
1-hexene comonomeric units and a melt index value of 1.0.+-.0.1
g/10 min. and (B) having a melt index value of 1.0.+-.0.1 g/10 min.
The melt index values are ("I.sub.2", 190.degree. C., 2.16 kg)
measured according to ASTM D1238-04. In some such embodiments, the
film may have a thickness of 0.0127 mm (0.5 mil) to 0.0635 mm (2.5
mils); and weight fractions of (A) and (B) in a range from 50 wt %
(A)/50 wt % (B) to 25 wt % (A)/75 wt % (B).
[0060] Olefin polymerization catalysts include Ziegler-Natta
catalysts, Chrome catalysts, and molecular catalysts. Ziegler-Natta
(Z-N) such as TiCl.sub.4/MgCl.sub.2 and Chrome catalysts such as a
chromium oxide/silica gel are heterogeneous in that their catalytic
sites are not derived from a single molecular species.
Heterogeneous catalysts produce polyolefins with broad molecular
weight distributions (MWD) and broad chemical composition
distributions (CCD). A molecular catalyst is homogeneous in that it
theoretically has a single catalytic site that is derived from a
ligand-metal complex molecule with defined ligands and structure.
As a result, molecular catalysts produce polyolefins with narrow
CCD and narrow MWD, approaching but in practice not reaching the
theoretical limit of Mw/Mn=2. Metallocenes are molecular catalysts
that contain unsubstituted cyclopentadienyl ligands (Cp).
Post-metallocene are derivatives of metallocenes that contain one
or more substituted CP ligands, such as constrained geometry
catalysts, or are non-sandwich complexes. Examples of
post-metallocene catalysts are bis-phenylphenoxy catalysts,
constrained geometry catalysts, imino-amido type catalysts,
pyridyl-amide catalysts, imino-enamido catalysts,
aminotroponiminato catalysts, amidoquinoline catalysts,
bis(phenoxy-imine) catalysts, and phosphinimide catalysts.
[0061] A compound includes all its isotopes and natural abundance
and isotopically-enriched forms. The enriched forms may have
medical or anti-counterfeiting uses.
[0062] In some aspects any compound, composition, formulation,
mixture, or reaction product herein may be free of any one of the
chemical elements selected from the group consisting of: H, Li, Be,
B, C, N, O, F, Na, Mg, Al, Si, P, S, Cl, K, Ca, Sc, Ti, V, Cr, Mn,
Fe, Co, Ni, Cu, Zn, Ga, Ge, As, Se, Br, Rb, Sr, Y, Zr, Nb, Mo, Tc,
Ru, Rh, Pd, Ag, Cd, In, Sn, Sb, Te, I, Cs, Ba, Hf, Ta, W, Re, Os,
Ir, Pt, Au, Hg, Tl, Pb, Bi, lanthanoids, and actinoids; with the
proviso that chemical elements required by the compound,
composition, formulation, mixture, or reaction product (e.g., C and
H required by a polyolefin or C, H, and O required by an alcohol)
are not excluded.
[0063] The following apply unless indicated otherwise.
Alternatively precedes a distinct embodiment. AEIC means
Association of Edison Illuminating Companies, Birmingham, Ala.,
USA. ASTM means the standards organization, ASTM International,
West Conshohocken, Pa., USA. IEC means the standards organization,
International Electrotechnical Commission, Geneva, Switzerland. ISO
means the standards organization, International Organization for
Standardization, Geneva, Switzerland. Any comparative example is
used for illustration purposes only and shall not be prior art.
Free of or lacks means a complete absence of; alternatively not
detectable. IUPAC is International Union of Pure and Applied
Chemistry (IUPAC Secretariat, Research Triangle Park, N.C., USA).
May confers a permitted choice, not an imperative. Operative means
functionally capable or effective. Optional(ly) means is absent (or
excluded), alternatively is present (or included). PPM are weight
based. Properties are measured using a standard test method and
conditions for the measuring (e.g., viscosity: 23.degree. C. and
101.3 kPa). Ranges include endpoints, subranges, and whole and/or
fractional values subsumed therein, except a range of integers does
not include fractional values. Room temperature: 23.degree.
C..+-.1.degree. C. Substantially free of a specific material means
0 to 1 wt %, alternatively 0 to <0.1 wt %, alternatively 0 wt %
of the material. Substituted when referring to a compound means
having, in place of hydrogen, one or more substituents, up to and
including per substitution.
[0064] Unless noted otherwise herein, use the following
preparations for characterizations.
[0065] Blend and Film Preparation Methods 1. A blown-film-line
machine configured for making polyethylene films with a feed hopper
in fluid communication with an extruder in heating communication
with a heating device heated to a temperature of 430.degree. C. The
extruder is in fluid communication with a die having a fixed die
gap of 1.778 millimeter (70 mils), a blow up ratio of 2.5:1. The
Frost Line Height (FLH) is 76.+-.10 centimeters (30.+-.4 inches)
from the die. The machine used a feed rate of (A) and (B), and
production rate of film, of 91 kg (201 pounds) per hour at
430.degree. C.
[0066] Density Test Method: measured according to ASTM D792-13,
Standard Test Methods for Density and Specific Gravity (Relative
Density) of Plastics by Displacement, Method B (for testing solid
plastics in liquids other than water, e.g., in liquid 2-propanol).
Report results in units of grams per cubic centimeter
(g/cm.sup.3).
[0067] Film Puncture Test Method: ASTM D5748-95(2012), Standard
Test Method for Protrusion Puncture Resistance of Stretch Wrap
Film. Determines the resistance to puncture of a film as resistance
to penetration of the film by a probe impinging the film at a
standard speed such as 250 millimeters per minute (mm/min.). The
probe is coated with a polytetrafluoroethylene and has an outer
diameter of 1.905 cm (0.75 inch). The film is clamped during the
test. The probe eventually penetrates or breaks the clamped film.
The peak force at break, i.e., the maximum force, energy (work) to
break or penetrate the clamped film, and the distance that the
probe has penetrated at break, are recorded using mechanical
testing software. The probe imparts a biaxial stress to the clamped
film that is representative of the type of stress encountered by
films in many product end-use applications. This resistance is a
measure of the energy-absorbing ability of a film to resist
puncture under these conditions.
[0068] Long Chain Branching (LCB) Test Method: calculate number of
long chain branches (LCB) per 1,000 carbon atoms of a test polymer
using a correlation developed by Janzen and Colby (J. Mol. Struct.,
485/486, 569-584 (1999)) between zero shear viscosity, .eta..sub.o,
and M.sub.w. Their correlation is drawn as a reference line on a
reference graph of .eta..sub.o on the y-axis and M.sub.w on the
x-axis. Then a test polymer is characterized by (a) and (b): (a)
using the Zero Shear Viscosity Determination Method described
later, measuring the test polymer's small-strain (10%) oscillatory
shear, and using a three parameter Carreau-Yasuda empirical model
("CY Model") to determine values for .eta..sub.o therefrom; and (b)
using the Weight-Average Molecular Weight Test Method described
later, measuring the test polymer's M.sub.w. Plot the results for
the test polymer's .eta..sub.o and M.sub.w on the reference graph,
and compare them to the reference line. Results for test polymers
with zero (0) long chain branching per 1,000 carbon atoms will plot
below the Janzen and Colby reference line, whereas results for test
polymers having long chain branching >0 per 1,000 carbon atoms
will plot above the Janzen and Colby reference line. The CY Model
is well-known from R. B. Bird, R. C. Armstrong, & O. Hasseger,
Dynamics of Polymeric Liquids, Volume 1, Fluid Mechanics, 2.sup.nd
Edition, John Wiley & Sons, 1987; C. A. Hieber & H. H.
Chiang, Rheol. Acta, 1989, 28: 321; and C. A. Hieber & H. H.
Chiang, Polym. Eng. Sci., 1992, 32: 931.
[0069] Melt index (190.degree. C., 2.16 kilograms (kg), "I.sub.2")
Test Method: for ethylene-based (co)polymer is measured according
to ASTM D1238-04, Standard Test Method for Melt Flow Rates of
Thermoplastics by Extrusion Platometer, using conditions of
190.degree. C./2.16 kilograms (kg), formerly known as "Condition E"
and also known as 12. Report results in units of grams eluted per
10 minutes (g/10 min.) or the equivalent in decigrams per 1.0
minute (dg/1 min.). 10.0 dg=1.00 g. Melt index is inversely
proportional to the weight average molecular weight of the
polyethylene, although the inverse proportionality is not linear.
Thus, the higher the molecular weight, the lower the melt
index.
[0070] Weight-Average Molecular Weight Test Method: determine
M.sub.w, number average molecular weight (M.sub.n), and
M.sub.w/M.sub.n using chromatograms obtained on a High Temperature
Gel Permeation Chromatography instrument (HTGPC, Polymer
Laboratories). The HTGPC is equipped with transfer lines, a
differential refractive index detector (DRI), and three Polymer
Laboratories PLgel 10 .mu.m Mixed-B columns, all contained in an
oven maintained at 160.degree. C. Method uses a solvent composed of
BHT-treated TCB at nominal flow rate of 1.0 milliliter per minute
(mL/min.) and a nominal injection volume of 300 microliters
(.mu.L). Prepare the solvent by dissolving 6 grams of butylated
hydroxytoluene (BHT, antioxidant) in 4 liters (L) of reagent grade
1,2,4-trichlorobenzene (TCB), and filtering the resulting solution
through a 0.1 micrometer (.mu.m) Teflon filter to give the solvent.
Degas the solvent with an inline degasser before it enters the
HTGPC instrument. Calibrate the columns with a series of
monodispersed polystyrene (PS) standards. Separately, prepare known
concentrations of test polymer dissolved in solvent by heating
known amounts thereof in known volumes of solvent at 160.degree. C.
with continuous shaking for 2 hours to give solutions. (Measure all
quantities gravimetrically.) Target solution concentrations, c, of
test polymer of from 0.5 to 2.0 milligrams polymer per milliliter
solution (mg/mL), with lower concentrations, c, being used for
higher molecular weight polymers. Prior to running each sample,
purge the DRI detector. Then increase flow rate in the apparatus to
1.0 mL/min/, and allow the DRI detector to stabilize for 8 hours
before injecting the first sample. Calculate M.sub.w and M.sub.n
using universal calibration relationships with the column
calibrations. Calculate MW at each elution volume with following
equation:
log M X = log ( K X / K PS ) a X + 1 + a PS + 1 a X + 1 log M PS ,
##EQU00001##
where subscript "X" stands for the test sample, subscript "PS"
stands for PS standards, a.sub.PS=0.67, K.sub.PS=0.000175, and
a.sub.X and K.sub.X are obtained from published literature. For
polyethylenes, a.sub.X/K.sub.X=0.695/0.000579. For polypropylenes
a.sub.X/K.sub.X=0.705/0.0002288. At each point in the resulting
chromatogram, calculate concentration, c, from a
baseline-subtracted DRI signal, I.sub.DRI, using the following
equation: c=K.sub.DRII.sub.DRI/(dn/dc), wherein K.sub.DRI is a
constant determined by calibrating the DRI, / indicates division,
and dn/dc is the refractive index increment for the polymer. For
polyethylene, dn/dc=0.109. Calculate mass recovery of polymer from
the ratio of the integrated area of the chromatogram of
concentration chromatography over elution volume and the injection
mass which is equal to the pre-determined concentration multiplied
by injection loop volume. Report all molecular weights in grams per
mole (g/mol) unless otherwise noted. Further details regarding
methods of determining Mw, Mn, MWD are described in US 2006/0173123
page 24-25, paragraphs [0334] to [0341].
[0071] Zero Shear Viscosity Determination Method: perform
small-strain (10%) oscillatory shear measurements on polymer melts
at 190.degree. C. using an ARES-G2 Advanced Rheometric Expansion
System, from TA Instruments, with parallel-plate geometry to obtain
complex viscosity |.eta.*| versus frequency (.omega.) data.
Determine values for the three parameters--zero shear viscosity,
.eta..sub.o, characteristic viscous relaxation time,
.tau..sub..eta., and the breadth parameter, a,--by curve fitting
the obtained data using the following CY Model:
.eta. * ( .omega. ) = .eta. .smallcircle. [ 1 + ( .tau. .eta.
.omega. ) .alpha. ] ( 1 - n ) a , ##EQU00002##
wherein |.eta.*(.omega.)| is magnitude of complex viscosity,
.eta..sub.o is zero shear viscosity, .tau..sub..eta. is viscous
relaxation time, a is the breadth parameter, n is power law index,
and w is angular frequency of oscillatory shear.
EXAMPLES
[0072] Constituent (A1): a ZN-LLDPE characterized by 1-butene
comonomeric content, a density of 0.918 g/cm.sup.3, and a melt
index I.sub.2 of 1.0 g/10 min.
[0073] Constituent (A2): a ZN-LLDPE characterized by 1-butene
comonomeric content, a density of 0.918 g/cm.sup.3, and a melt
index I.sub.2 of 2.0 g/10 min.
[0074] Constituent (A3): a ZN-LLDPE characterized by 1-hexene
comonomeric content, a density of 0.918 g/cm.sup.3, and a melt
index I.sub.2 of 1.0 g/10 min.
[0075] Constituent (B1): a MCN-LLDPE characterized by 1-hexene
comonomeric content, a density of 0.918 g/cm.sup.3, and a melt
index I.sub.2 of 1.0 g/10 min.
[0076] Comparative Example 1a (CE1a): a 0.0127 mm thick film of 100
wt % (A1).
[0077] Comparative Example 1b (CE1b): a 0.0127 mm thick film of 100
wt % (B1).
[0078] Comparative Example 2a (CE2a): a 0.0127 mm thick film of 100
wt % (A2).
[0079] Comparative Example 2b (CE2b): a 0.0127 mm thick film of 100
wt % (B1).
[0080] Comparative Example 3a (CE3a): a 0.0127 mm thick film of 100
wt % (A3).
[0081] Comparative Example 3b (CE3b): a 0.0127 mm thick film of 100
wt % (B1).
[0082] Inventive Example 1a (IE1a): a polyolefin blend and a 0.0127
mm thick film of 75 wt % (A1) and 25 wt % (B1).
[0083] Inventive Example 1b (IE1b): a polyolefin blend and a 0.0127
mm thick film of 50 wt % (A1) and 50 wt % (B1).
[0084] Inventive Example 1c (IE1c): a polyolefin blend and a 0.0127
mm thick film of 25 wt % (A1) and 75 wt % (B1).
[0085] Inventive Example 2a (IE2a): a polyolefin blend and a 0.0127
mm thick film of 75 wt % (A2) and 25 wt % (B1).
[0086] Inventive Example 2b (IE2b): a polyolefin blend and a 0.0127
mm thick film of 50 wt % (A2) and 50 wt % (B1).
[0087] Inventive Example 2c (IE2c): a polyolefin blend and a 0.0127
mm thick film of 25 wt % (A2) and 75 wt % (B1).
[0088] Inventive Example 3a (IE3a): a polyolefin blend and a 0.0127
mm thick film of 75 wt % (A3) and 25 wt % (B1).
[0089] Inventive Example 3b (IE3b): a polyolefin blend and a 0.0127
mm thick film of 50 wt % (A3) and 50 wt % (B1).
[0090] Inventive Example 3c (IE3c): a polyolefin blend and a 0.0127
mm thick film of 25 wt % (A3) and 75 wt % (B1).
[0091] The comparative and inventive films (0.0127 mm thickness,
0.5 mil) were tested for film puncture according to the Film
Puncture Test Method. Compositions and test results are reported
below in Tables 1 to 3.
TABLE-US-00001 TABLE 1 Compositions (1.0 MI 1-butene ZN-LLDPE/1.0
MI MCN-LLDPE) and Film Puncture Test Results. ("0" means 0.00)
Constituent (wt %) CE1a IE1a IE1b IE1c CE1b ZN-LLDPE (A1) 100 75 50
25 0 MCN-LLDPE (B1) 0 25 50 75 100 Example Total 100.00 100.00
100.00 100.00 100.00 Actual Film Puncture 21.36 21.40 22.20 24.33
20.99 (J/cm.sup.3, 0.0127 mm thick) Comparative trend line 21.36
21.27 21.18 21.09 20.99 Film Puncture (J/cm.sup.3, 0.0127 mm thick)
Film Puncture 0 0.13 1.02 3.24 0 Enhancement (J/cm.sup.3) Film
Puncture 0 0.61 4.8 15 0 Enhancement (%)
TABLE-US-00002 TABLE 2 Compositions (2.0 MI 1-butene ZN-LLDPE/1.0
MI MCN-LLDPE) and Film Puncture Test Results. ("0" means 0.00)
Constituent (wt %) CE2a IE2a IE2b IE2c CE2b ZN-LLDPE (A2) 100 75 50
25 0 MCN-LLDPE (B1) 0 25 50 75 100 Example Total 100.00 100.00
100.00 100.00 100.00 Actual Film Puncture 10.24 16.28 20.38 17.84
20.99 (J/cm.sup.3, 0.0127 mm thick) Comparative trend line 10.24
12.93 15.62 18.30 20.99 Film Puncture (J/cm.sup.3, 0.0127 mm thick)
Film Puncture 0 3.35 4.76 (0.46) 0 Enhancement (J/cm.sup.3) Film
Puncture 0 26 30.5 (2.5) 0 Enhancement (%)
TABLE-US-00003 TABLE 3 Compositions (1.0 MI 1-hexene ZN-LLDPE/1.0
MI MCN-LLDPE) and Film Puncture Test Results. ("0" means 0.00)
Constituent (wt %) CE3a IE3a IE3b IE3c CE3b ZN-LLDPE (A3) 100 75 50
25 0 MCN-LLDPE (B1) 0 25 50 75 100 Example Total 100.00 100.00
100.00 100.00 100.00 Actual Film Puncture 19.62 23.05 28.86 30.04
20.99 (J/cm.sup.3, 0.0127 mm thick) Comparative trend line 19.62
19.96 20.31 20.65 20.99 Film Puncture (J/cm.sup.3, 0.0127 mm thick)
Film Puncture 0 3.09 8.55 9.39 0 Enhancement (J/cm.sup.3) Film
Puncture 0 15 42 45 0 Enhancement (%)
[0092] Film puncture resistance enhancement (J/cm.sup.3)=actual
film puncture resistance (J/cm.sup.3)--film puncture resistance
expected from comparative trend line (J/cm.sup.3), wherein "-"
indicates subtraction. Film puncture resistance enhancement
(%)=(Film puncture resistance enhancement (J/cm.sup.3)/(film
puncture resistance expected from comparative trend line,
((J/cm.sup.3)), expressed as a percentage, wherein "/" indicates
division. The greater the increase in puncture resistance value
relative to the comparative trend line puncture resistance value,
the greater the puncture resistance enhancement.
[0093] As shown by the data in Tables 1 to 3, the inventive
polyethylene blends and films have weight fraction concentrations
of 75 wt % ZN-LLDPE/25 wt % MCN-LLDPE, 50 wt % ZN-LLDPE/50 wt %
MCN-LLDPE, and 25 wt % ZN-LLDPE/75 wt % MCN-LLDPE, and enhanced
puncture resistance of from 0.13 to 9.4 J/cm.sup.3, and 0.6% to 45%
relative to expected puncture resistance values at the same weight
fraction concentrations as derived from a comparative trend line
for actual comparative puncture resistance values at 100% ZN-LLDPE
and 100 wt % MCN-LLDPE.
[0094] Puncture resistance test results are also available for
comparative that are identical to CE1 a, CE1 b, CE2a, CE2b, CE3a,
and CE3b and inventive examples that are identical to IE1 a to
IE1c, IE2a to IE2c, and IE3a to IE3c except wherein thickness of
the film is 0.0381 mm (1.5 mil) or 0.0635 mm (2.5 mils).
[0095] Incorporate by reference here the below claims as numbered
aspects except replace "claim" and "claims" by "aspect" or
"aspects," respectively.
* * * * *