Note: Descriptions are shown in the official language in which they were submitted.
CA 02345502 2001-04-30
2
STAND-UP POLYMERIC BAGS
FIELD OF INVENTION
s The present invention relates generally to the packaging industry and, more
particularly, to stand-up polymeric bags.
BACKGROUND OF THE INVENTION
The use of inexpensive food packaging bags has become very common,
to especially in the food industry. These food packaging bags have been
popular for a
number of reasons including the fact that they can be conveniently stored.
Some of
these packages are reclosable via the use of a reclosable feature such as a
resealable
adhesive seal or a reclosable zipper. The zippers can be opened and closed
either by
pressure or by the use of an auxiliary slider mechanism. Food packaging bags,
is especially reclosable packages, are a great convenience to the consumer
especially for
storing various food products. Often, the stored food items are desired to be
heated or
re-heated before serving to consumers. Consumers typically heat the food
products in
heating apparatus such as a microwave or a conventional oven.
Existing food packaging bags are often undesirable for heating in the above-
zo described heating apparatus for a variety of reasons. Some commonly used
materials
for forming food packaging bags include low density polyethylenes (LDPE) and
linear
low density polyethylenes (LLDPE). Food packaging bags~(2-5 mils thickness)
made
of LDPE or LLDPE bags often do not have the modulus, stiffness and/or
mechanical
strength to be stable and stand up when being heated. The loss of stiffness
and stand
zs up characteristics at higher temperatures is evident at the temperatures
generated in
microwaves and conventional ovens. A loss of stand-up nature in a food
packaging
bag may result in spillage of food or liquid. Moreover, this can lead to
extreme
customer dissatisfaction if the food or liquid contacts a hand, an arm or
apparel of a
customer. Even if the food or liquid does not contact a customer, it is not
aesthetically
3o pleasing to observe food or liquid leaving the packaging bag.
Accordingly, a need exists for a food packing bag that overcomes the above-
noted shortcomings.
CHICAGO 58902v1 47097-01003
CA 02345502 2001-04-30
SUMMARY OF THE INVENTION
According to one embodiment, a stand-up polymeric bag comprises first and
second opposing body panels and a bottom wall. The first and second opposing
body
panels are coupled to opposing portions of the bottom wall. At least one of
the first
s opposing body panel, the second opposing body panel and the bottom wall
comprises a
layer of from about 5 to about 95 wt.% of a polyolefinic resin and from about
5 to
about 95 wt.% of a cyclic olefin copolymer. The cyclic olefin copolymer has a
glass
transition temperature, TG, of greater than about 20°C as determined by
ASTM
D3418.
to According to another embodiment, a stand-up polymeric bag comprises first
and second opposing body panels and a bottom wall. The first and second
opposing
body panels are coupled to opposing portions of the bottom wall. At least one
of the
first opposing body panel, the second opposing body panel and the bottom wall
includes a layer from about 5 to about 95 wt.% of a polyolefinic resin and
from about
is 5 to about 95 wt.% of a cyclic olefin copolymer. The cyclic olefin
copolymer
comprises from about 10 to about 90 mol.% of norbornene.
According to a further embodiment, a stand-up polymeric bag comprises first
and second opposing body panels and a bottom wall. The first and second
opposing
body panels are coupled to opposing portio_~~ of the bottom wall. At least one
of the
2o first opposing body panel, the second opposing body panel and the bottom
wall
includes a first layer comprising from about 5 to 100 wt.% of a cyclic olefin
copolymer
and a second layer comprising from about 5 to 100 wt.% of a polyolefinic
resin. The
cyclic olefin copolymer has a glass transition temperature, TG, of greater
than about
20°C as determined by ASTM D3418.
2s According to yet embodiment, a stand-up polymeric bag comprises first and
second opposing body panels and a bottom wall. The first and second opposing
body
panels are coupled to opposing portions of the bottom wall. At least one of
the first
opposing body panel, the second opposing body panel and the bottom wall
comprises a
first layer of from about 5 to i 00 wt.% of a cyclic olefin copolymer and a
second layer
3o comprising from about 5 to 100 wt.% of a polyolefinic resin. The cyclic
olefin
copolymer comprises from about 10 to about 90 mol.% of norbornene.
CHICAGO 58902v1 47097-01003
CA 02345502 2001-04-30
4
BRIEF DESCRIPTION OF THE DRAWINGS
Other objects and advantages of the invention will become apparent upon
reading the following detailed description and upon reference to the drawings.
FIG. I is a perspective view of a bag according to one embodiment of the
s present invention;
FIG. 2 is a cross-sectional view taken generally along the line 2-2 in FIG. I
;
FIG. 3 is a perspective view of a bag having body panels comprising two
layers according to another embodiment of the present invention;
FIG. 4 is a cross-sectional view taken generally along the line 4-4 in FIG. 3;
to FIG. 5 is a cross-sectional view taken generally along the line 5-5 in FIG.
3;
FIG. 6 is a perspective view of a bag having body panels comprising three
layers according to a further embodiment of the present invention;
FIG. 7 is a cross-sectional view taken generally along the line 7-7 in FIG. 6;
FIG. 8 is a perspective view of a bag portion of FIG. 1 including a fastener
and
Is slider according to yet another embodiment of the present invention;
FIG. 9 is a cross-sectional view taken generally along the line 9-9 in FIG. 8
that
includes an enlarged perspective view of the fastener of FIG. 8;
FIG. 10 is a side view of a bag in a closed position according to yet another
embodin.:.~~ of the present invention; and
2o FIG. 11 is a perspective view of the bag of FIG. 10 in an open position.
While the invention is susceptible to various modifications and alternative
forms, specific embodiments thereof have been shown by way of example in the
drawing and will herein be described in detail. It should be understood,
however, that
it is not intended to limit the invention to the particular forms disclosed
but, on the
2s contrary, the intention is to cover all modifications, equivalents, and
alternatives falling
within the spirit and scope of the invention as defined by the appended
claims.
DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS
According to one embodiment of the packaging bags or pouches shown in
3o FIGS. 1 and 2, is a stand-up polymeric bag 10. The stand-up polymeric bag
10
comprises first and second body panels 12 and 14 and a bottom wall 16. The
first and
second opposing body panels 12 and 14 are coupled to opposing portions of the
bottom wall 16. The first and second opposing body panels 12 and 14 are
fixedly
CHICAGO 58902v1 47097-01003
CA 02345502 2001-04-30
connected to each other along a pair of sides 18 and 20. The bottom wall 16
extends
between the pair of sides 18 and 20. The bottom wall 16 of FIG. 1 is a
gusseted
bottom wall that comprises two gusseted portions 16a and 16b. It is
contemplated that
the bottom wall 16 may be comprised of other configurations than a gusseted
bottom
s wall, such as shown in FIG. 1. Another configuration of a bottom wall will
be
discussed later with respect to FIGS. 10 and 11.
The body panels 12 and 14 of the stand-up polymeric bag 10 comprise a cyclic
olefin copolymer and a polyolefinic resin. The cyclic olefin copolymer and the
polyolefinic resin may be blended to form the body panels (i.e., a monolayer).
This is
to shown in the bag 10 of FIGS. 1 and 2, for example. The body panels
generally
comprise from about 5 wt.% to about 95 wt.% of the cyclic olefin copolymer and
from
about 5 wt.% to about 95 wt.% of the polyolefinic resin. The body panels
typically
comprise from about 5 wt.% to about 50 wt.% of the cyclic olefin copolymer and
from
about 50 wt.% to about 95 wt.% of the polyolefinic resin. More specifically,
the body
is panels comprise from about 5 wt.% to about 25 wt.%, from about 10 wt.% to
about
20 wt.%, or from about 15 wt.% or about 20 wt.% of the cyclic olefin
copolymer, and
from about 75 wt.% to about 95 wt.%, from about 80 wt.% to about 90 wt.%, or
from
about 80 wt.% to about 85 wt.% of the polyolefinic resin.
20 ~clic olefin copol~rmers
The cyclic olefin copolymers of the present invention generally have a
molecular weight distribution, or polydispersity, (MW/M", "MWD") from about
2.0 to
about 5.0, and preferably from about 2.0 to about 2.5.
The cyclic olefin copolymers generally have a density of from about 0.90 to
2s about 1.10 g/cm3, typically from about 0.95 to about 1.05 g/cm3 and more
typically
from about 1.00 to about 1.03 g/cm3. The heat deflection temperature (HDT,
measured at 66 psi) of cyclic olefin copolymers generally is from about 50 to
about
200°C, and typically from about 70 to about 170°C.
The melt flow index (MI) of the cyclic olefin copolymers is generally from
3o about 1 to about 100 g/10 min., and typically from about 4 to about 20 g/10
min. at
115°C (239°F) above its corresponding HDT as determined by ISO
1133.
The cyclic olefin copolymers may be made from copolymers of ethylene and
norbornene. The mole % of ethylene and norbornene may vary with respect to
each
CHICAGO 58902v1 47097-01003
CA 02345502 2001-04-30
6
other For example, the amount of norbornene is generally from about 10 to
about 90
mol.%, with the remainder being ethylene (from about 10 to about 90 mol.%).
The
amount of norbornene is typically from about 20 to about 70 mol.% with the
remainder
being ethylene. The amount of norbornene is more typically from about 35 to
about 60
s mol.% with the remainder being ethylene. The cyclic olefin copolymers may be
made
using metallocene catalysts.
The glass transition temperature (Tg) of the cyclic olefin copolymer is
generally
greater than about 20°C, typically greater than about 50°C, and
preferably greater than
about 75°C, as measured by ASTM D3418. The glass transition temperature
of the
to cyclic olefin copolymer may be greater than about 100°C or about
150°C as measured
by ASTM D3418. The glass transition temperature (T~) of the cyclic olefin
copolymers increases as the mole % of norbornene in the copolymer increases.
For
example, the glass temperature transition (Tg) of a cyclic olefin copolymer
comprising
20 mol.% norbornene and 80 mol.% ethylene is about 25°C, while the
glass
is temperature transition of a cyclic olefin copolymer comprising 70 mol.%
norbornene
and 30 mol.% ethylene is about 210°C. The glass temperature transition
(Tg) of a
cyclic olefin copolymer comprising 30 mol.% norbornene and 70 mol.% ethylene
is
about 75°C, while a cyclic olefin copolymer comprising 60 mol.%
norbornene and 40
mol.% ethylene is about 180°C.
2o The flexural modulus of the cyclic olefin copolymer is generally from about
300,000 to about 600,000 psi, and more specifically from about 400,000 to
about
500,000 psi as measured by ASTM D790. The tensile mbdulus of the cyclic olefin
copolymers is generally from about 300,000 to about 600,000 psi, and more
specifically from about 400,000 to about 500,000 psi, as determined by ISO
527.
is Useful cyclic olefin copolymers are available from several companies. For
example, Ticona, a business of Celanese AG, in Summit N.J. has cyclic olefin
copolymers available. Other companies that have cyclic olefin copolymers
available
include Nippon Zeon (Japan), Mitsui Chemical (Japan) and JSR (Japan), formerly
know as Japan Synthetic Rubber. Ticona, a business of Celanese AG, has
so commercially available cyclic olefin copolymers (COCs) under the
designation
TOPAS~. These cyclic olefin copolymers are believed to be prepared with
feedstocks
of norbornene and ethylene and the use of a metallocene catalyst. There are
believed
to be at least four grades of TOPAS~ resins available (TOPAS~ 8007, TOPAS~
CHICAGO 58902v1 47097-01003
CA 02345502 2001-04-30
7
6013, TOPAS~ 601 S and TOPAS~ 6017). The four grades of TOPAS~ resins
available have glass transition temperatures, Tg, of 80, 140, 160 and
180°C,
respectively. The corresponding norbornene levels of the four grades of TOPAS~
resins are believed to be about 3S, 48, SS and S9 mole %.
s
Polyolefinic Resins
The polyolefinic resins that may be used in the present invention include low
density polyethylenes (LDPE), linear low density polyethylenes (LLDPE), high
density
polyethylenes (HI~PE), medium density polyethylenes (1VIDPE), polypropylenes,
to plastomers, ethylene vinyl acetates (EVA), polymethylpentene copolymers and
combinations thereof. It is contemplated that other polyolefinic resins may be
used.
The preferred polyolefinic resins are low density polyethylenes and linear low
density
polyethylenes.
The polyolefinic resin may include a small amount of an alkenyl aromatic
is polymer (e.g., polystyrene). For example, the alkenyl aromatic polymer may
be added
in an amount up to about 1 or about 2 wt. % of the polyethylene. Further
details may
be obtained from U.S. Patent Nos. 4,579,912, 4,716,201, 4,743,649 and
4,804,564.
In another embodiment of the present invention, the body panels comprise a
first layer comprising a cyclic olefin cu~olymer and a second layer comprising
a
2o polyolefinic resin. This is shown, for example, in FIGS. 3-5 with a bag
having panels
made from two layers. The stand-up polymeric bag 110 of FIG. 3 has a body
panel
112 that comprises a first layer 112a and a second layer '112b. Similarly,
stand-up
polymeric bag 110 has a body panel 114 that comprises a first layer 114a and a
second
layer 114b.
zs The first layers 112a and 114a comprise a cyclic olefin copolymer, while
the
second layers 112b and 114b comprise a polyolefinic resin. The compositions of
the
first layers 112a and 114a do not necessary have to be made of identical
materials.
Likewise, the second layers 112b and 114b may be comprised of independently
selected polyolefinic resins.
3o The first layers 112a and I 14a may comprise a cyclic olefin copolymer and
a
polyolefinic resin. The first layers 112a and 114a generally comprise from
about 5
wt.% to 100 wt.% of the cyclic olefin copolymer and from about 0 wt.% to about
9S
wt.% of the polyolefinic resin. The first layers 112a and 114a typically
comprise from
CHICAGO 58902v1 47097-01003
CA 02345502 2001-04-30
8
about 5 wt.% to about 50 wt.% of the cyclic olefin copolymer and from about 50
wt.%
to about 95 wt.% of the polyolefinic resin. The first layers 112a and 114a may
comprise from about 5 wt.% to about 25 wt.%, from about 10 wt.% to about 20
wt.%, or from about 15 wt.% or about 20 wt.% of the cyclic olefin copolymer,
and
s from about 75 wt.% to about 95 wt.%, from about 80 wt.% to about 90 wt.%, or
from
about 80 wt.% to about 85 wt.% of the poiyolefinic resin.
It is preferred that the first layers 112a and 114a are located on the
exterior of
the bag, while the second layers 112b and 114b are located on the interior of
the bag.
This is the embodiment depicted in FIGS. 3 and 4. It is contemplated, however,
that at
to least one of the first layers 112a and 114a may be located on the interior
of the bag
with at least one of the second layers 112b and 114b being located on the
exterior of
the bag.
Referring to FIG. 5, a cross-sectional view of line 5-5 of FIG. 3 is shown
that
depicts a two-layer bottom 116. The bottom wall 116 comprises a first layer I
16a and
is a second layer 116b that is similar to that described above with respect to
the first and
second layers 112a, b and 114x, b of FIGS. 3 and 4. It is contemplated,
however, that
the first layer 116a may be located on the interior of the bag.
In another embodiment of the present invention shown in FIGS. 6 and 7, a
stand-up polymeric bag 210 includes bocy panels 212 and 214, a bottom wall 216
and
2o a pair of sides 218 and 220. The body panel 212 includes a first layer 212a
comprising
a cyclic olefin copolymer, and second and third layers 212b and 212c
comprising
independently selected polyolefinic resins. The first layer 2~12a is located
between the
second layer 212b and the third layer 212c, with the second layer 212b being
located
on the exterior of the bag. The third layer 212c may comprise a polyolefinic
resin such
zs as those described above or may be a heat-sealable polyolefin, such as
LLDPE or
LDPE.
It is contemplated that other three layered body panels may be made, as well
as
body panels having four or more layers. The body panels may further include a
barrier
layer to prevent or inhibit oxygen, carbon dioxide or other gases from
reaching the
3o contents in the interior of the bag. Alternatively, the body panel may
include a
breathable layer such as, e.g., polymethylpentene copolymer, to enhance the
permeation of oxygen, carbon dioxide and other gases.
CHICAGO 58902v1 47097-01003
CA 02345502 2001-04-30
9
The body panels of the present invention have enhanced stiffness. This allows
the body panels to have a desired stiffness at a downgauged thickness as
compared to
existing body panels. The enhanced stiffness at elevated temperatures is
measured in
increased tensile modulus and flexural modulus.
s The stand-up polymeric bags may further include a reclosable feature or
fastener, such as a resealable adhesive seal or a reclosable zipper. The
zipper can be
opened and closed either by pressure or by the use of an auxiliary slider
mechanism.
One example of a zipper is shown in FIGS. 8 and 9 in stand-up polymeric bag
300. The stand-up polymeric bag 300 of FIGS. 8 and 9 includes a zipper 352
to extending along a mouth formed opposite the bottom (not shown) of the bag
300. The
zipper 352 includes a male track and a female track. The male track includes a
male
profile 3 54 and a first depending fin or flange 3 56 extending downward from
the male
profile 354. Likewise, the female track includes a female profile 358 and a
second
depending fin or flange 360 extending downward from the female profile 358.
The
is flanges 356 and 360 are shown attached to opposing body panels 312 and 314.
Of
course, the one-layered body panels 312 and 314 may be made of two or more
layers,
such as described above in body panels 112 and 212.
To assist in opening the bag 300, a slider 362 is slidably mounted to the
zipper
352 for movement between a closed position and an open position. In the open
2o position of the slider 362, the male and female profiles 354 and 358 are
disengaged
from each other so that a user can gain access to the interior of the bag 300.
Movement of the slider 362 from the open position to the~closed position
interlocks
the male and female profiles 3 S4 and 3 58 so as to restrict access to the
interior of the
polymeric bag 300.
2s End termination clamps 364 are mounted to opposite ends of the zipper 352.
The end clamps 364 prevent the slider 362 from going past the ends of the
zipper 352
and hold the male and female profiles 354 and 358 together to resist stresses
applied to
the profiles during normal use of the plastic bag 300. Further details
concerning the
construction and operation of the slider 362 and the end clamps 364 may be
obtained
3o from United States Patent No. 5,067,208 to Herrington, Jr. et al., which is
incorporated herein by reference in its entirety.
CHICAGO 58902v1 47097-01003
CA 02345502 2001-04-30
1
As discussed above, it is contemplated that the bags of the present invention
may use other reclosable features such as a resealable adhesive seal or a
reclosable
fastener that does not include the use of a slider.
According to yet another embodiment, a packaging bag or pouch shown in
s FIGS. 10 and 11 is a stand-up polymeric bag 400. The stand-up polymeric bag
400 is
of a different configuration than shown in, for example, FIG. 1. The present
invention, however, is not limited to the shown bags. It is contemplated that
other
bags may include the body panels of the present invention.
Referring to FIGS. 10 and 11, the stand-up polymeric bag 400 includes a body
to panel 412, an opposing body panel 414, and a bottom 416. In FIG. 10, the
bottom is
located between the opposing body panels 412 and 414 and extends from a bottom
edge 492 to a hidden line 480. As shown in FIG. 1 I , the bottom 416 includes
three
integrally connected portions 416a, 416b and 416c.
Lines of attachment 488, as shown in FIGS. 10 and 11, assist in forming the
Is bottom 416. The lines of attachment 488 are depicted in FIGS. 10 and 11 as
attaching
a portion of the body panel 412 to the bottom 416. Similarly, lines of
attachment 490
of FIG. 11 are shown that attach a portion of the body panel 414 to the bottom
416.
The lines of attachment 488 and 490 divide the bottom 416 into portions 416a,
416b
and 416c. The lines of attachment 488 and 490 of FIGS. 10 and 11 are generally
zo straight lines that extend from a bottom edge 492 of the bag to sides 418
or 420. The
lines of attachment of 488 are at an angle B, as depicted in FIG. 10. The
angle B is
generally from about 30 to about 60 degrees as taken from tile bottom edge
492a. The
lines of attachment 488 and 490 may be shaped differently and proceed at
different
angles B. The lines of attachment may be formed by heat-sealing.
zs The bottom edge 492 may include a sealed edge portion 492a that attaches
the
body panel 412 and the bottom portions 416b and 416c. Similarly, the bag 400
may
include a second bottom edge 494 and a sealed edge portion 494a. The sealed
edge
portion 494a attaches the body panel 414 and the bottom portions 416b and
416c.
The stand-up polymeric bag 400 also includes a slider 462 and end termination
3o clips 464, such as those described above (slider 62 and end termination
clip 64). It is,
however, not necessary for the bag 400 to include a fastener.
According to another embodiment, the stand-up polymeric bags of the present
invention may further include a vented option. A vented polymeric bag may
provide
CHICAGO 58902v1 47097-01003
CA 02345502 2001-04-30
faster and more uniform heating, as well as extending the preservation time of
the
heated food. In addition, a vented stand-up polymeric bag may further assist
in
avoiding a spill from the bag because the bag would not likely need to be
opened
during the heating process. The contents of the bags, however, may still leak
through
s the vented option. Leaks from the vented option are less likely when a more
tortuous
path is created for the contents of the bags to leak.
The vented option is preferably located near the mouth of the bag, but may be
in other locations, such as the sides. The vented option may be a small hole,
a plurality
of small holes or a one-way valve. An example of a vented option is shown in
U. S.
to Patent Nos. 6,010,244 and 4,532,652, which is hereby incorporated by
reference in its
entirety.
Processes
The body panels of the present invention may be formed by extruding or
is coextruding one or more layers using conventional techniques known to those
skilled
in the art. For example, a first layer comprising a cyclic olefin copolymer
portion and a
second layer comprising a polyolefinic resin may be coextruded. The
polyolefinic resin
of the second layer may be a polyethylene, such as LLDPE or LDPE. A third-
layer
body panel may be coextruded with an ~:,ater layer comprising a polyolefinic
resin, a
zo middle layer comprising a cyclic olefin copolymer, and an inner layer
comprising a
heat-sealable polyolefin, such as LLDPE or LDPE. Alternatively, the layers may
be
laminated in forming the three-layer structure.
The polyolefinic resin and the cyclic olefin copolymer may also be blended in
forming the body panels. These resins may be extruded in forming the body
panels of
2s the present invention. According to another process of the present
invention, the body
panels of the present invention may be formed from blown processes or cast
film
processes.
The overall thickness of the bags or pouches may vary, but is generally from
about 1 to about 5 mils, and typically from about 2 to about 4 mils. The
overall
3o thickness of the bags or pouches is more typically from about 3 to about 4
mils. In the
embodiments that include body panels having more than one layer, the thickness
of the
layers may vary between the layers and are likely dependent on the end use of
the bag.
One contemplated embodiment is a 4.0 mil three layer body panel that includes
a 0.5
CHICAGO 58902v1 47097-01003
CA 02345502 2001-04-30
12
mil middle layer comprising a cyclic olefin copolymer and outer polyethylene
layers
(3.5 mils total).
The bags or pouches of the present invention may store items such as food
products or liquids. This includes, but is not limited to, soups, pre-packaged
foods,
s lasagna, chicken, meats, vegetables, liquids and left-over products.
The bags or pouches of the present invention are preferably capable of being
heated at higher temperatures, such as those generated in microwaves and
conventional ovens.
to Examples
Bag Testing
The results of the bag testing appear in Table 1. The bags (Bags 1-6) were
formed manually. Each of the bags had a width of 12 inches, a height of 7
inches and a
is depth of 6 inches. The thickness of the film used in forming the bags were
either 2
mils or 4 mils. Each of the bags had a track on which a slider opened/closed
the bag.
The bags also included clips at opposing ends of the track.
All of the body panels used in forming Bags 1-6 of Table 1 were made of a
single layer. Bags 1-6 were made of different materials, but all included at
least one
20 linear low density polyethylene (LLDPE). Bags 3-6 further included a cyclic
olefin
copolymer. In Bags 3-6, the cyclic olefin copolymers and the LLDPE were
blended
and extruded as a monolayer film. The monolayer film was used in forming the
body
panels.
The LLDPE resin used in Bag 1 from Dow Chemical had a melt index of 1.0
2s g/10 min. as measured by ASTM D1238, and a density of about 0.926 g/cm3.
The
other LLDPE resin used in Bags 2-6 was from Eastman Chemical Company. The
Eastman resin had a melt index of 0.5 g/10 min. as measured by ASTM D1238, and
a
density of about 0.928 g/cm~. The Eastman LLDPE resin used in Table 1
fi.lrther
contained an added 2.5 wt.% slip and antiblock polyethylene concentrate and
1.25
so wt.% of a process aid concentrate.
There were two different types of cyclic olefin copolymers that were used in
making Bags 3-6 of Table 1. The first cyclic olefin copolymer was TOPAS ~ 6013
made by Ticona, a business of Celanese AG. The TOPAS ~ 6013 had a melt index
of
CHICAGO 58902v1 47097-01003
CA 02345502 2001-04-30
13
16 g/ 10 min. as measured by ISO 1 133, a temperature glass transition (Tg) of
140°C
and a density of 1.02 g/cm3. The second cyclic olefin copolymer was TOPAS ~
6015
made by Ticona, a business of Celanese AG. The TOPAS ~ 6015 had a melt index
of
16 g/ 10 min. as measured by ISO I 133, a temperature glass transition (T~) of
160 °C
s and a density of 1.02 g/cm3.
As shown in Table 1, Bag i was comprised of 100 wt.% LLDPE from Dow
Chemical, while Bag 2 was comprised of 100 wt.% of LLDPE from Eastman. Bags 3-
were made of Eastman LLDPE and TOPAS ~ 6013 in various weight percentages.
Bag 3 was made of 95 wt.% of Eastman LLDPE and 5 wt.% of TOPAS ~ 6013. Bag
l0 4 was made of 90 wt.% of Eastman LLDPE and 10 wt.% of TOPAS ~ 6013, while
Bag 5 was made of 80 wt.% of Eastman LLDPE and 20 wt.% of TOPAS ~ 6013.
Bag 6 was made of 90 wt.% of Eastman LLDPE and 10 wt.% of TOPAS ~ 6015.
Before water was added to the bags, the bags were visually inspected to
determine if each of the bags stood up. The results of the visually inspection
are
Is shown in Table 1 in the "Stand Up" columns.
The bags were tested in a microwave and included the following tests: the
boiling water test, the frozen chili test and the frozen pizza test. The
"boiling water"
test was performed on all of the bags and consisted of adding 1.5 liter of
water to each
cf the bags. The water that was added to the bags was initially at room
temperature.
zo The added water had a depth or fill of about 2 to 2.5 inches in the bag.
The bags were then heated in the microwave for about 7 minutes at high power
until the water was at its boiling temperature (about 200PF). The bags were
then
qualitatively evaluated by visually inspecting the bag to determine if the bag
was still
standing up or if sagging occurred.
2s The "frozen chili" test consisted of placing the content of the two cans of
Hormel~ Chili without beans (each can was I S ounces, 425 grams) in the bag.
The
chili was placed in the freezer for at least 36 hours. The frozen chili was
removed from
the freezer and heated for about 7.5 minutes in the microwave at high power.
After
being heated in the microwave for this duration, the chili was at a
temperature of about
30 150 to about 165°F.
The "frozen pizza" test started with 3 pieces of cheese pizza in the bag being
placed in the freezer for at least 36 hours. The frozen pizza slices were
removed from
the freezer and heated for about 3 minutes in the microwave at high power.
After
CHICAGO 58902v1 47097-01003
CA 02345502 2001-04-30
14
being heated in the microwave for this duration, the cheese pizza was at a
temperature
of about 140 to about 195°F.
In Table 1, the boiling water test is referred to as the "water test", the
frozen
chili test is referred to as the "chili test", and the frozen pizza test is
referred to as the
"pizza test". The boiling water test was performed on Bags 1-6. The frozen
chili test
was performed on Bag 3, while the frozen pizza test was performed on Bags 4-5.
Table 1
ThicknessWater Chili Pizza
Test Test Test
Bag Composition (mil) Stand Sag Stand Sag Stand Sag
Up (%) Up Up (~%)
No.
1 100 wt.% 4 Yes 50% ~6 ~, -
LLDPE~ g
2 100 wt.% 4 Yes 100%' NT NT
LLDPE
3 95 w2.% LLDPEZ~ Yes 10%,-'BYes 0% NT
5 wt.% COC3
d 90 wt.% LLDPE14 Yes 0%'v NT Yes 10/$
10 wt.% COC3
80 wt.% LLDPE24 Yes 10%5~8NT Yes X10/$
- -
20 wt.% COC'
6 90 wt.% LLDPE'4 Yes 10%'~ NT NT
10 wt.% COC
1 The LLDPE from Dow Chemical had a melt index of 1.0 g/10 min. and a density
of 0.926 g/cm'.
2 The LLDPE from Eastman Chemical with a melt index of 0.5 g/10 min. and a
density of 0.928 g/cm'.
3 Cyclic olefin copolymer (COC}-TOPAS~ 6013 with a melt index of 16 g/10 min.
and a density of 1.02
g/cm'.
4 Cyclic olefin copolymer (COCA TOPA S~ 6015 with a melt index of 16 g/10 min.
and a density of 1.02
p~cm'.
5 After 7. S minutes
6 NT = not tested
7 After 6. S minutes
8 The sagging % was located near the clip of the bag
As shown in Table 1, bags without the cyclic olefin copolymers (COC) showed
significantly poorer results in the boiling water test. Specifically, Bags 1
and 2 had
2s 50% and 100% sag, respectively, as compared to Bags 3-6 (bags comprising a
COC)
that had 10% or less of sagging. Bag 3, 5 and 6 had 10% sag near the clip,
while Bag
4 did not have any sagging in the boiling water test. The boiling water test
reported in
Table 1 tested at least two different bags of the same composition (Bags 1-6).
Bags 3-5 also showed great results in other tests performed. The frozen chili
3o test and the frozen pizza test was performed twice on the same bag.
Specifically, the
bag that was tested in the frozen chili test (Bag 3) and the bags tested in
the frozen
pizza test (Bags 4 and 5) showed good results in that they all had 10% or less
of
sagging. In fact, Bag 3 did not show any sagging after being tested in the
frozen chili
CHICA(i0 58902v1 47097-01003
CA 02345502 2001-04-30
test. It was surprising 'that a small amount of a cyclic olefin copolymer
would produce
the results shown in the boiling test, frozen chili test and the frozen pizza
test.
Example 2
The films as shown in Table 2 (Films 1-5) were tested for various mechanical
s properties. Specifically, tensile, elongation and modulus properties of the
films were
determined in accordance with ASTM D882. The visual appearance of Films 1-5 is
also shown in Table 2 below.
Film 1 comprised 100 wt.% of linear low density polyethylene from Dow
Chemical Company having a melt index of 2.0 g/10 min. as determined by ASTM
to D1238 and a density of 0.926 g/cm3. Films 2-5 comprised either 80 or 95
wt.% of the
Dow Chemical LLDPE resin with the remainder being either TOPAS~ 8007 or
TOPAS~ 6013. The average thicknesses of the films was from 2.5 to 3 mils. The
tested films were formed by a cast process.
15 TABLE 2
F5lm LLDPE' COCi Tensile ElongationModulus Appearance
No. (wt. %) (wt. (kpsi (% at (kpsi)
%) at break)
break)
1 100 0 4.38 661 26.4 Clear
2 95 5 6._' 794 46.6 Clear
3 85 15' 4.83 556 67.4 Clear
4 95 5 3.01 605 18.4 Hazy
5 85 15 4.25 646 ~ 52.0 Hazy
1 The LLDPE had a melt index of 2.0 g/10 min. and a density of 0.926 g/cm'.
2 COC = cyclic olefin copolymer.
3 The COC was TOPAS~ 8007 with a melt index of 4.5 ml/ l0 min and a density of
1.02 g/cm'
4 The COC was TOPAS~ 6013.
Films 2, 3 and 5, with the cyclic olefin copolymer showed excellent modulus as
zs compared to Film 1. Each of the modulus of Films 2, 3 and 5 was almost
twice as high
as the modulus value of Film 1 (the film without a cyclic olefin copolymer).
Compare
46.6, 67.4 and 52.0 kpsi vs. 26.4 kpsi in Table 2. The amount of increased
modulus in
Films 2, 3 and 5 was surprising considered the amount of cyclic olefin
copolymer
added (either 5% or 15%). Film 4 showed a reduced modulus as compared to Film
1.
3o The modulus of Films 2, 3 and 5 were especially surprising because the
elongation
CHICAGO 58902v1 47097-01003
CA 02345502 2001-04-30
16
values of Films 2, 3 and 5 were not much lower than the elongation value of
Film 1
(compare 794, 556 and 646% vs. 661% in Table 2). In fact, the elongation of
Film 2
was actually higher than the elongation of Film 1.
The tensile values of Films 2 and 3 were higher than that of Film 1 (compare
6.25 and 4.83 vs. 4.38 kpsi in Table 2), while the tensile value of Film S was
slightly
lower than Film 1 (4.25 kpsi vs. 4.38 kpsi). The appearance of the film was
clear for
Films 1-3, but was hazy for Films 4 and 5 that included TOPAS~ 6013. It is
believed
that the greater amount of norbornene included in TOPAS~ 6013, as compared to
TOPAS~ 8007, produces a film that is hazy.
Io Example 3
The films of Table 2 were used in forming Bags 1-5. Bags 1-5 were tested to
determine if the bags were self standing or could be made to stand-up with the
addition
of 1. S liters of water. The average thicknesses of the films used to form
Bags 1-5 was
from 2.5 to 3 mils. The films used in forming the bags were cast mono-layer.
t 5 TABLE 3
Bag No.s LLDPEI COCZ Stand Up Test
w2. % Wt.
1 l 00 0 No
2 95 5' Yes, but with
water inside
3 85 15 Yes
4 95 _ 5 Yes, but with
water inside
85 15' Yesb
1 The LLDPE had a melt index of 2.0 g/ 10 min. and a density of 0.926 g/cm'.
2 COC = cyclic olefin copolymer.
2o 3 The COC was TOPAS~ 8007 with a melt index of 4.5 g/10 min. and a density
of 1.02 g/cm'.
4 The COC was TOPAS~ 6013.
5 Bags 1-5 had a width of 5.5 inches and a height of 7 inches.
6 In addition to standing-up on its own and with the addition of water, Bag 5
also was a stand-up bag after being
heated in a microwave at high power temperature for 2 minutes with water.
Bags 3 and 5 with the cyclic olefin copolymer were self stand up bags without
the addition of water. Bags 2 and 4 with the cyclic olefin copolymer were
stand-up
bags with the addition of water. Bag 1, however, without the cyclic olefin
copolymer
3o did not stand up with or without the addition of the water.
While the present invention has been described with reference to particular
embodiments, those skilled in the art will recognize that many changes may be
made
thereto without departing from the spirit and scope of the present invention.
Each of
these embodiments and obvious variations thereof is contemplated as falling
within the
3s spirit and scope of the claimed invention, which is set forth in the
following claims.
CHICAGO 58902v1 47097-01003
