Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
42E71A CA 02279391 1999-07-30
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MULTICOMPARTMENT THERMOPLASTIC BAG
The present invention relates to reclosable thermoplastic bags. More
particularly, the present invention relates to reclosable thermoplastic bags
having multiple
compartments.
~, Reclosable thermoplastic bags are commonly used in food packaging. The
bags are generally made out of a plastic film and have two side walls that are
'-~aect at the
bottom and sealed at the sides. The bags typically have a reclosable fastener
at the top of
the bag, such as, for example, an adhesive, a wire tie, or a plastic zipper
such as that
described in U.S. Patent 5,140,727, issued to Dais et al.
to The consumers that use these bags often need more than one bag at any
given time. Therefore, bags having more than one compartment have been
developed.
For example, U.S. Patent 4,993,844 discloses a compartmented pouch. However,
the
closures in the pouch of the '844 patent are displaced relative to one
another, making it
difficult for a consumer to close one compartment without squashing the cont,--
,nts of another
compartment. Furthermore, the '844 patent describes a shared wall for the
compartments,
which restricts the available volume inside the compartment. Another example
is U.S.
Patent 5,024,536, which describes a resealable compartmented bag. However, ti-
'e '536
patent describes the compartments of the boa as being sealed together along
the bottom
edges of the compartments. thereby restricting the available volume insice the
o compartments.
Document US-~-s,92i,s05 shows a laboratory specimen bag having a
sealable fluid tight compartment for the specimen and a second compartment
for containing associated paper work. The compartments are f=ee from
attachment to each other at the bottom ends and adjacent walls of the
compartments are joined at the top end. In document US-~-3,-'_69,76S a
method of manufacturing dual compartment containers is described in which
an accordion folded web is sealed at its sides and along the top to form the
sealed containers.
AMENDED S~fET
CA 02279391 1999-07-30
_.p . . , .
. " .,
It would be an advance in the art of compartmented bags to provide a
multicompartment bag in which all of the compartmrents can be closed
simultaneously but
opened independently of one another, and in which the available volume inside
the
compartments is maximized. a,"
?5 The present invention provides such a reclosable thermoplastic container
having a plurality of compartments. In one aspect, the present invention is a
multicompartment reclosable thermoplastic bag comprising at least tlVO
compartments, each
compartment having a top, a bottom, side edges, and two opposing Slae~walls
jeir~ed at the
side edges and the bottom, each compartment having a closure across the tep
thereof, the
.0 closures being arranged back-to-back, the closures being aligned such that
th= center
F~oints of each closure are less than 1/2 inch (1.27 cm) away from. e~cri
ot~~er, wherein ti-~e
compartments are attached together proximate the tops cf the CGmpariWent" ari~
the
bottoms of the Compai tmcntS are free from being attached t0 each GthEr.
AR,~EML~p ~~T
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In a further aspect, the present invention provides a method of
using a reclosable thermoplastic bag having first and second compartments,
comprising the steps of:
simultaneously closing the first and second compartments; and
opening one of the first and second compartments while leaving
the other of the first and second compartments closed; and
opening the other of the first and second compartments, the first
opening step requiring greater force than the second opening step.
The multicompartment bag of the present invention is advantageous because al!
to of the compartments can be closed simultaneously, but each compartment can
be opened
independently of the other compartments, if desired. Furthermore, the volume
available
inside the compartments of the multicompartment bag of the present invention
is increased
because the compartments are not attached to each other along the bottom.
Another
advantage of the present invention is that the multicompartment bag can be
made using a
15 single sheet of thermoplastic film.
Fig. 1 is a perspective view of the multicompartment thermoplastic bag of the
present invention.
Fig. 2 is a sectional view of the bag of Fig. 1.
Fig. 3 is a sectional view of a closure used in the bag of Fig. 1.
20 Fig..4 is a plan view of an extruded sheet used to make the
multicompartment
bag of the present invention.
Fig. 5 is a perspective view of the sheet of Fig. 4.
Fig. 1 illustrates a multicompartment reclosable thermoplastic bag 10 of the
present invention. Bag 10 includes at least two compartments 15 and 16. Each
25 compartment 15 and 16 has a top, a bottom, side edges, and two opposing
sidewalls joined
at the side edges and the bottom. Thus, compartment 15 has a bottom edge 17
and two
opposing side edges. Compartment 16 likewise has a bottom edge 18 and two
opposing
side edges. Each compartment also has a closure element across the top
thereof. Thus,
compartment 15 has closure 31 across the top thereof, while compartment 16 has
closure
30 32 across the top thereof. The bag 10 also includes means for joining the
compartments i 5
and 16 proximate to the tops thereof.
2
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Each sidewall of compartments 15 and 16 is made of a layer of thermoplastic
film Thus, bag 10 includes at least four layers of film 11 12 13 and 14. Each
layer 11 12 13
and 14 has a top edge, a bottom edge and two opposing side edges. Layers 11
and 12 are
attached along the bottom and the side edges to form the compartment 15.
Layers 13 and
14 are attached along the bottom and the side edges to form the compartment
16. Thus,
as shown, layer 1 i is an outer layer of the first compartment, while layer 12
is an inner layer
of the first compartment. Likewise, layer 14 is an outer layer of the second
compartment
while layer 13 is an inner layer of the second compartment.
1o Fig. 2 illustrates a sectional view of an embodiment of the bag of the
present
invention. The layers 11 12 13 14 can be made from any suitable thermoplastic
film such
as, for example, low density polyethylene, linear low density polyethylene,
substantially
linear copolymers of ethylene and a C3-C8 a-olefin, polypropylene,
polyvinylidene chloride,
ethylene vinyl acetate, pofylactic acid, mixtures of two or more of these
polymers, or
mixtures of one of these polymers with another thermoplastic polymer. The film
can be a
co-extruded film, if desired.
Bottom edge 17 of compartment 15 and bottom edge 18 of compartment 16
can be formed using any desired method. For example, the bottom edges can be
formed by
folding the film, by heat sealing, by ultrasonic sealing, by an adhesive seal,
or by any other
2o desired method.
The side edges of compartments 15 and 16 are formed by joining layers of
film along the side edges thereof using any desired method. For example, the
side edges
can be formed by hot wire sealing, hot knife sealing, ultrasonic sealing, an
adhesive seal, or
by any other desired method. The result is that every two layers of film are
joined together
such that two layers together form a compartment. Thus, in Figs. 1 and 2,
layers 11 and 12
are joined together to form compartment 15, while layers 13 and 14 are joined
together to
form compartment 16. If desired all layers can be joined along the side edges.
The bag 10 includes means for joining compartment 15 and compartment 16
proximate to the tops of the compartments, so that the bag 10 is a single
unit.
3o Compartments 15 and 16 can be joined, proximate to the tops, in any desired
manner. For
example, the compartments can be joined by a continuous or intermittent heat
seal or
ultrasonic seal.
3
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Alternatively, as shown in Fig. 3, the compartments can be joined by a fold 52
in the film at the top of the bag between layers 12 and 13. Fold 52 can be
above or below_
the fasteners. In a preferred embodiment, fold 52 extends about 0.5 inches
above the
bottom of the fasteners.
Alternatively, the means for joining compartments 15 and 16 can be an
adhesive 36 disposed continuously or intermittently between layers 12 and 13.
The
adhesive is preferably applied to a point proximate to the closures. Suitable
adhesives
include any adhesive that provides sufficient adhesion to the film layers 12
and 13 so that
the layers remain attached while compartments 15 and/or 16 are opened.
Examples of
to such adhesives include HM2707 and HL2203, available.commercially from H. B.
Fuller. An
adhesive is especially useful when closure elements are disposed along both
layers 12 and
13, in order to stabilize and align the closures.
Compartments can be joined by any other suitable means, such as, for
example, by extruded lamination of a polymer such as low density polyethylene.
The effect
15 of joining the compartments proximate to the top is to minimize movement of
the aligned
closure elements with respect to each other. When movement of the closures is
minimized,
it is easier for a consumer to close the compartments simultaneously and to
open one or
more compartments.
As shown in Fig. 3, in a preferred embodiment, both a fold 52 and an
2o adhesive 36 are used as means for joining the compartments. In this
embodiment, the
adhesive 36 is applied from the point of fold 52 down to a point at least
between the profiles
31 b and 32b. This distance can be as high as 0.5 inches (12.7 mm), although
preferably
the adhesive is applied in a band having a width of from about 1/8 inch (3.17
mm) to about
1/16 inch (1.59 mm). Preferably the adhesive is applied between the profiles
31 b 32b or
25 above the profiles 31 b 32b.
The bag 10 includes a closure disposed along the top of each compartment,
so that each compartment 15 and 16 has a complete closure across the top. The
term
"closure element" is defined herein to mean one part of a closure. For
example, on a zipper
closure, a closure element is one profile or the other of the zipper, e.g., a
rib profile or a
3o groove profile. On an adhesive closure, a closure element is one adhesive
strip or the
other. The closure elements can be post-applied, integral or laminated to the
film, all of
which are commonly known methods of applying closures to reclosable
thermoplastic bags.
In one embodiment, a double-sided zipper tape can be laminated to the tops
of layers 12 and 13. A double-sided zipper tape is one in which both sides of
the zipper
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tape have a profile of a plastic zipper on it, i.e., a rib profile or a groove
profile. The profiles
extend outwardly from each side of the zipper tape such that a single zipper
tape contains _
two profiles extending therefrom.
Fig. 3 illustrates a sectional view of closures 31 and 32 which can be used
for
the present invention. Closures 31 and 32 can be any suitable closures. For
example, as
shown, closure 31 can be a plastic zipper having interlockable profiles 31 a
and 31 b, and
closure 32 can also be a plastic zipper having interlockable profiles 32a and
32b. However,
the closures can be adhesive closures or any other suitable reclosable
closures, if desired.
The profiles 31 a, 31 b, 32a and/or 32b of the plastic zipper are disposed
l0 along the tops of layers 11 12 13 and 14, so that each compartment has a
complete closure
along the top thereof. The closure on any two compartments need not be the
same,
although they can be. For example, one compartment might have a plastic zipper
while
another compartment might have an adhesive closure.
The closures on each compartment are substantially aligned with each other
15 such that all of the compartments can be closed with a single motion on the
part of a
consumer. In this manner, all of the compartments can be closed
simultaneously. The term
"aligned" is defined herein to mean that the center points of the profiles are
lined up such
that, as seen from a front view, only one closure element can be seen, with
all of the other
closure elements being lined up substantially behind that closure element and
thus
2o substantially hidden from view. Preferably, the closure elements are
aligned such that the
center points are less than or equal to 1/2 inch (1.27 cm) away from each
other. More
preferably, the center points are 1/4 inch (0.63 cm) away from each other, and
most
preferably, the center points are 1/8 inch (0.32 cm) away from each other.
As shown in Figs. 1-3, the closures are positioned such that the rib profiles
25 31 b and 32b are aligned with each other. In the embodiment shown, the rib
profiles are
positioned back-to-back. The term "back-to-back" is defined herein to mean
that the closure
elements are positioned substantially adjacent to each other but extend away
from each
other. In the embodiment shown, closure element 31 b is positioned adjacent
closure
element 32b, and closure elements 31 b and 32b are positioned such that the
closure face
3o away from each other. Thus, closure elements 31 b and 32b are said to be
aligned back-to-
back.
Back-to-back alignment eases the ability for a consumer to interlock both
closures 31 and 32 on both compartments 15 and 16 in a single motion. On the
other
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WO 98J33717 PCT/US98/00412
hand, closures 31 and 32 can be opened independently from one another, such
that one
compartment can be opened while the other compartment remains closed.
In one embodiment, the bag can be designed such that one closure will open
preferentially. In other words, when the bag has two adjacent compartments
with plastic
zippers disposed across the tops thereof, the force required to open one of
the plastic
zippers can be modified to be greater than the force required to open the
other plastic
zipper. The opening force can be modified using any desired means. For
example, the
opening force of a plastic zipper can be modified by altering the profile
geometry. Examples
include making the groove of one groove profile bigger or making the rib of
one rib profile
1o thinner, or altering one or more of the radii of the various hooks in the
closure. Alternatively,
the opening force of a plastic zipper can be modified by changing the type of
plastic to one
that has different friction characteristics.
The compartments can be of equal size, although they need not be.
Preferably, the compartments all have equal width, although the depths of the
compartments can vary. For example, all of the compartments might have a 6.5
inch (16.51
cm) width and an 8 inch {20.32 cm) depth. Alternatively, all of the
compartments might
have a 6.5 inch (16.51 cm) width, while one compartment has an 8 inch (20.32
cm) depth
and another compartment has a 6 inch (15.24 cm) depth.
The thicknesses of the layers of film can be equal or the thicknesses can
2o vary. For example, if desired, all of layers 11, 12, 13 and 14 can have a
thickness in the
range of from 2.5 mils (0.0635 mm) to.5.0 mils {0.127 mm), which is a typical
thickness of a
ZIPLOC brand freezer bag. Alternatively, the layers can all have thicknesses
in the range
from 1.75 mils (0.0445 mm) to 2.7 mils (0.0686 mm), which is a typical
thickness of a
ZIPLOC brand storage bag, or the layers 11, 12, 13 and 14 can all have
thicknesses in the
range of from 1.0 mils (0.0254 mm) to 1.2 mils (0:0305 mm), which is a typical
thickness of
a ZIPLOC brand sandwich or snack bag. On the other hand, the layers 11, 12, 13
and 14
can all have different thicknesses, which can be any combination of the above
thicknesses.
Moreover, one or more of layers 11, 12, 13 and/or 14 can be even thinner, from
0.6 mils
(0.0152 mm) to 1.2 mils (0.0305 mm). The desired thickness of the various
layers depends
3o upon the final use of the multicompartment bag. For example, thicker layers
of film are
general useful for longer term storage, whereas thinner film thicknesses are
useful for items
which will be used in the short term. Thinner layers also tend to cling to the
packaged
material better than thicker layers.
6
CA 02279391 2004-08-04
-7-
If desired, one or more of the layers can be microperforated. The term
"micro perforated" means that the film has small holes therein. Such a
microperforated film makes the compartment suitable for storing produce
therein, as
the microperforated film allows the produce to breathe. Preferably, the
microperforations, or holes, have a size in the range of from 200 microns to
about
900 microns. If desired, different layers can have different patterns of
microperforations therein. For example, layer 12 might have microperforations
in the
range of from 200 to 300 microns, while layer 13 can have microperforations of
from
800 to 900 microns. Preferably, the density of the microperforations is from
100
microperforations to 500 microperforations per layer of film, for a 6.625 inch
(16.83
cm) by 7 inch (17.78 cm) layer of film. The microperforations can be evenly
dispersed across a layer or can be clustered in groups of several
microperforations.
Furthermore, different layers of film can have different patterns of
microperforations.
Generally, any combinations of patterns of microperforations can be used. The
microperforations can be formed using any conventional method such as a hot
needle perforator. More details about microperforated bags are described in
U.S.
Patent 5,492,705.
If desired, one or more of the layers can be embossed. Embossing creates a
texture on the surface of the film. Embossing thus provides a visual cue to
the
consumer that one layer of film is different than the other layers, as the
texture
scatters the light differently, thereby changing the appearance of the film.
Moreover,
the textured surface adheres to the stored food better than a smooth surface
does.
Any combination of layers can be embossed.
The preferred method of making the bag of the present invention begins with
an extrusion process well known in the art. The bag is made with a large
extruded
sheet of thermoplastic film. Fig. 4 illustrates an example of such an extruded
sheet
40 that can be used to make the bag of the present invention. The sheet 40
comprises at least four panels 41, 42, 43 and 44, each panel representing a
layer of
film in the final bag. Thus, the panels 41, 42, 43 and 44 correspond to the
layers
11,12,13 and 14 in the bag shown in Figs. 1-2. The panels 41, 42, 43 and 44
can be
the same size, or the size of the panels can vary according to the desired
size of the
final compartments.
As shown, extruded sheet 40 contains profiles 31 a, 31 b, 32a and 32b integral
therewith. However, if desired, profiles31 a, 31 b, 32a and 32b can be post-
applied,
i.e., applied after the film is extruded, or profiles 31 a, 31 b, 32a and 32b
can be
attached to the sheet by laminating a zipper tape thereto. In one embodiment,
a
double-sided zipper tape
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having profile 31 b on one side thereof and profile 32b on the other side, can
be laminated
to the sheet. When the profiles are extruded integrally with sheet 40,
preferably, profiles
31 b and 32b are side by side on the sheet 40, so that when the sheet 40 is
folded, as
described below, the profiles 31 b and 32b are back to back.
s If desired, any or all of the panels 41, 42, 43 or 44 can be microperforated
or
embossed. In this manner, the final bag will have some or all layers which
will be
microperforated or embossed. Furthermore, if the final bag is to have layers
of varying
thicknesses, the extruder die lip can be designed such that the die gap
varies, thereby
forming an extruded sheet 40 that has multiple thicknesses. When the sheet 40
is folded,
1o as described below, the layers will then have varying thicknesses.
Fig. 5 illustrates the manner in which the sheet 40 can be folded to make the
bag of the present invention. The sheet 40 can be folded along lines 51, 52
and 53. The
folds will form the bottom edges 17 and 18 along the fold lines 51 and 53,
respectively.
The fold along line 52 will position the profiles 31 b and 32b back to back.
~5 Fold line 52 is also the point at which the compartments 15 and 16 are
joined. The fold
along lines 51 and 53 enable the profiles 31 a and 32a to be aligned with
profiles 31 b and
32b to close the compartments. Preferably, the extruded sheet is thinner
proximate to the
fold line 52, referred to herein as the "thinner section". The thinner section
permits easier
folding. More preferably, the thinner section is less than or equal to half as
thick as the rest
20 of the extruded sheet. Even more preferably, the thinner section is from
0.5 mils (0.0127
mm) to 2.0 mils (0.0508 mm) thick and yet even more preferably from 1.0 mils
(0.0254 mm)
to 1.5 mils thick (0.0381 mm). If the thinner section is too thin, the sheet
will tear easily,
whereas if the thinner section is too thick, the sheet wilt not fold easily.
Preferably, the
thinner section is 1/4 inch (6.35 mm) wide or less.
25 If desired, as the extruded sheet 40 is being folded, and adhesive can be
disposed along the back of the sheet on either side of the fold line 52. In
this manner, when
the sheet 40 is folded, the compartments will be joined by the fold as well as
by the
adhesive disposed along the sheet. The adhesive allows better alignment of the
zipper
profiles, because profiles 31 b and 32b will be held in place and free from
movement with
3o respect to one another. Normally, the compartments are also joined by the
side seals.
After the sheet is folded and the adhesive is applied, the sheet is heat
sealed
along the edges of the bag. The heat seating permeates all of the panels, or
layers of the
bag. The heat seal can be accomplished by use of a hot wire, a hot knife, or
any other
desired means. In this manner, the side edges of the compartments are formed.
8
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If desired, the sheet can be corona-treated before being folded. Corona
treating permits printing to be easily applied to the bag surface. For
example, a stripe can -
be printed along the bottom of one or more of the compartments in order to
give a visual
cue to the consumer as to the location of the bottom of the compartment.
The following examples are not meant to limit the scope of the invention.
EXAMPLE 1
A multicompartment bag having two compartments is made. The first
compartment has the dimensions 6.625 inches long (16.83 cm) by 7 inches wide
(17.78
cm). The second compartment has the dimensions 4.75 inches tong (12.06 cm} by
7 inches
wide (17.78 cm).
Both of the sidewalls of the first compartment are 1.1 mils (0.028 mm) thick
on average. Both of the sidewalls of the second compartment are 1.1 mils
(0.028 mm) thick
on average. A groove profile of a plastic zipper is disposed along the outer
layer of the first
compartment, formed by a cast integral extrusion process. Likewise, a groove
profile of a
I5 plastic zipper is disposed along the outer layer of the second compartment,
formed by a
cast integral extrusion process. The rib profiles are aligned back-to-back
along either side
of a double-sided zipper tape, which is laminated to the top of the inner
layer of the first
compartment.
The two compartments are joined by a fold in the film between the fwo inner
layers and by side seals along the side edges of the bag. The fold is about
0.5 inches (1.27
cm) below the plastic zipper when the zipper is closed. The laminated double-
sided zipper
tape extends upwardly from the fold such that the rib profiles on either side
of the zipper
tape can come into contact with and interlock with the groove profiles,
thereby closing the
compartments.
EXAMPLE 2
A multicompartment bag having two compartments is made. The first
compartment has the dimensions 6.625 inches long (16.83 cm) by 7 inches wide
(17.78
cm). The second compartment has the dimensions 4.75 inches long (12.06 cm) by
7 inches
wide {17.78 cm).
Both of the sidewalls of the first compartment are 1.1 mils thick (0.028 mm)
on average. Both of the sidewalls of the second compartment are 1.1 mils thick
(0.028 mm)
on average. A plastic zipper is disposed along the tops of both the first and
second
compartments.
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The two compartments are joined by a fold in the film between the two inner
layers and by an adhesive disposed between the two inner layers. In addition,
the
compartments are joined by side seals along the side edges of the bag.
EXAMPLE 3
A multicompartment bag having three compartments is made. The first
compartment has the dimensions 8.5 inches long (21.59 cm) by 7 inches wide
(17.78 cm).
The second compartment is 6.625 inches long (16.83 cm) by 7 inches wide (17.78
cm).
The third compartment is 4.75 inches long (12.06 cm) by 7 inches wide (17.78
cm).
The thicknesses of both of the sidewalls of the first compartment are 2.2 mils
to on average (0.056 mm). The thicknesses of both of the sidewalls of the
second
compartment are 1.1 mils on average (0.028 mm). The thicknesses of both of the
sidewalls
of the third compartment are 1.1 mils on average (0.028 mm).
A plastic zipper is disposed along the tops of both the first and second
compartments. An adhesive closure is disposed along the top of the third
compartment.
The compartments are joined by a fold in the film between adjacent layers
and by an adhesive disposed between the adjacent layers. In addition, the
compartments
are joined by side seals along the side edges of the bag.
EXAMPLE 4
A multicompartment bag having two compartments is made. The first
2o compartment has the dimensions 6.625 inches long (16.83 cm) by 7 inches
wide (17.78
cm). The second compartment has the dimensions 4.75 inches long (12.06 cm) by
7 inches
wide (17.78 cm).
The thicknesses of both of the sidewalls of the first compartment are 1.1 mils
on average (0.028 mm). The thicknesses of both of the sidewalls of the second
compartment are 1.1 mils on average (0.028 mm}. A plastic zipper is disposed
along the
tops of both the first and second compartments.
The two compartments are joined by a fold in the film between the two inner
layers and by an adhesive disposed between the two inner layers. In addition,
the
compartments are joined by side seals along the side edges of the bag.
The outer layer of the first compartment, which corresponds to layer 11 of
Fig. 1, is microperforated. The microperforations have a diameter of 250
microns on
average. There are 500 microperforations on the layer.
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The outer layer of the second compartment, which corresponds to layer 14 of
Fig. 1, is microperforated. The microperforations have a diameter of 850
microns on
average. There are 100 microperforations on the layer.
EXAMPLE 5
A multicompartment bag having two compartments is made. The first
compartment has the dimensions 6.625 inches long (16.83 cm) by 7 inches wide
(17.78
cm}. The second compartment also has the dimensions 6.625 inches long (16.83
cm} by 7
inches wide (17.78 cm).
The thickness of the outer sidewafl of the first compartment is 3.5 mils on
to average (0.089 mm). The thickness of the inner sidewall of the first
compartment is 0.8 mils
on average (0.020 mm}. Likewise, the thickness of the outer sidewall of the
second
compartment is 3.5 mils on average (0.089 mm), and the thickness of the inner
sidewall of
the second compartment is 0.8 mils on average (0.020 mm). A plastic zipper is
disposed
along the tops of both the first and second compartments.
The two compartments are joined by a fold in the film between the two inner
layers and by an adhesive disposed between the two inner layers. In addition,
the
compartments are joined by side seals along the side edges of the bag.
The inner layers of both the first and second compartments are embossed.
The pattern on the embossed layers appears to be a repeating diamond-shaped
pattern.
While certain representative embodiments and details have been shown for
purposes of illustrating the invention, it will be apparent to those skilled
in the art that
various changes in the methods and apparatus disclosed herein may be made
without
departing from the scope of the invention, which is defined in the appended
claims.
11
