U.S. patent application number 11/257856 was filed with the patent office on 2007-04-26 for reclosable pouches or bags having front panel containment zipper.
Invention is credited to David J. Anzini, Rusty E. Koenigkramer, David J. Matthews, Lars G. Wihlborg.
Application Number | 20070092166 11/257856 |
Document ID | / |
Family ID | 37744405 |
Filed Date | 2007-04-26 |
United States Patent
Application |
20070092166 |
Kind Code |
A1 |
Anzini; David J. ; et
al. |
April 26, 2007 |
Reclosable pouches or bags having front panel containment
zipper
Abstract
Flexible containers that are hermetically resealable after
initial opening. The resealable containers are of a type that
comprises front and rear panels forming an interior volume that is
accessible by means of a resealable plastic zipper attached to the
front panel only. Each zipper comprises a pair of extruded plastic
zipper strips. The zipper strips are flattened and joined to each
other at the ends and are further joined to each other, without
substantial deformation of the closure profiles, in respective
transition areas substantially contiguous with the flattened ends.
These transition areas of zipper strip joinder assist in providing
a leakproof transition from the openable section of the zipper to
where the closure profiles have been fused and flattened (i.e.,
crushed).
Inventors: |
Anzini; David J.;
(Middletown, NY) ; Koenigkramer; Rusty E.;
(Nanuet, NY) ; Matthews; David J.; (Gilman,
IL) ; Wihlborg; Lars G.; (Stratford, CT) |
Correspondence
Address: |
Dennis M. Flaherty, Esq.;Ostrager Chong Flaherty & Broitman P.C.
Suite 825
250 Park Avenue
New York
NY
10177-0899
US
|
Family ID: |
37744405 |
Appl. No.: |
11/257856 |
Filed: |
October 25, 2005 |
Current U.S.
Class: |
383/63 ; 383/203;
383/210; 383/61.2; 383/66 |
Current CPC
Class: |
B65B 9/213 20130101;
B65D 33/2541 20130101; B65B 9/20 20130101; B65D 33/2583 20130101;
B65D 33/2508 20130101; B65B 2220/08 20130101; B65B 61/188 20130101;
B65D 33/2533 20130101; B65B 2051/105 20130101 |
Class at
Publication: |
383/063 ;
383/066; 383/061.2; 383/203; 383/210 |
International
Class: |
B65D 33/16 20060101
B65D033/16; B65D 33/00 20060101 B65D033/00 |
Claims
1. A reclosable package comprising: a zipper comprising first and
second zipper strips that have respective portions fused together
in first and second zipper end seals, said first zipper strip
comprising a length of a first closure profile having at least two
projecting elements and first and second flanges extending in
opposite directions and connected to said first closure profile,
respective portions of said first and second flanges being
flattened within the boundaries of said first and second zipper end
seals, and said second zipper strip comprising a length of a second
closure profile having at least one projecting element that fits
between said at least two projecting elements of said first closure
profile and a third flange connected to said second closure
profile, respective portions of said third flange being flattened
within the boundaries of said first and second zipper end seals,
said first and second zipper end seals respectively comprising
first and second substantially flat portions and first and second
transition areas respectively connected to said first and second
substantially flat portions on first, second and third sides,
wherein along said first and third sides of each of said first and
second transition areas, each of the two projecting elements of
said first and second closure profiles that are furthest apart from
each other is fused to some portion of the one of said first and
second zipper strips of which said respective one of said
furthest-apart projecting elements does not form a part; and
wherein along a second side of and within each of said first and
second transition areas, said first and second closure profiles are
deformed and fused together but not flattened, the respective ends
of the fused material along said second side being integrally
connected to the fused material of said first and third sides,
respectively, said third flange being longer than said first flange
and extending beyond said first and second zipper end seals in an
elevational direction; and a receptacle comprising top and bottom
seals, a first panel connected to and extending between said top
and bottom seals, and a second panel connected to and extending
between said top and bottom seals, said first and second panels
bounding an interior volume of said receptacle, wherein each of
said first through third flanges is joined to said first panel and
not joined to said second panel.
2. The reclosable package as recited in claim 1, wherein said first
and second closure profiles have a contact area in the range of 33
to 76%.
3. The reclosable package as recited in claim 1, wherein each of
said first and second closure profiles comprises two hooked
projecting elements and a hookless projecting element.
4. The reclosable package as recited in claim 1, further comprising
a peel seal joined to said first and third flanges along their
length.
5. The reclosable package as recited in claim 1, further comprising
a line of weakness formed in a portion of said first panel that
connects the respective portions of said first panel that are
joined to said first and third flanges.
6. The reclosable package as recited in claim 5, further comprising
a racetrack-shaped zone in which said first panel is joined to said
first and third flanges by means of sealant material having a
melting point lower than the melting point of the zipper
material.
7. The reclosable package as recited in claim 6, wherein each of
said first and second zipper end seals extends from an elevation
lower than said first and second closure profiles to an elevation
higher than a top edge of said first flange, and overlaps a
respective portion of said racetrack-shaped zone of joinder.
8. The reclosable package as recited in claim 1, further comprising
food product inside said receptacle.
9. The reclosable package as recited in claim 1, further comprising
liquid inside said receptacle.
10. The reclosable package as recited in claim 1, further
comprising pressurized gas inside said receptacle.
11. The reclosable package as recited in claim 1, further
comprising a vacuum inside said receptacle.
12. A reclosable package comprising: a zipper comprising first and
second zipper strips that have respective portions fused together
in first and second zipper end seals, said first zipper strip
comprising a length of a first closure profile and first and second
flanges extending in opposite directions and connected to said
first closure profile, respective portions of said first and second
flanges being flattened within the boundaries of said first and
second zipper end seals, and said second zipper strip comprising a
length of a second closure profile interlockable with said first
closure profile and a third flange connected to said second closure
profile, respective portions of said third flange being flattened
within the boundaries of said first and second zipper end seals,
said first and second zipper end seals respectively comprising
first and second transition areas disposed at opposite ends of said
first and second closure profiles, and first and second
substantially flat portions that respectively border said first and
second transition areas on three sides thereof, said first
transition area comprising first sections of said first and second
closure profiles that have been deformed and at least partially
fused together but not flattened, and said second transition area
comprising second sections of said first and second closure
profiles that have been deformed and at least partially fused
together but not flattened, said third flange being longer than
said first flange and extending beyond said first and second zipper
end seals in an elevational direction; and a receptacle comprising
top and bottom seals, a first panel connected to and extending
between said top and bottom seals, and a second panel connected to
and extending between said top and bottom seals, said first and
second panels bounding an interior volume of said receptacle,
wherein each of said first through third flanges is joined to said
first panel and not joined to said second panel.
13. The reclosable package as recited in claim 12, wherein said
first and second closure profiles have a contact area in the range
of 33 to 76%.
14. The reclosable package as recited in claim 12, further
comprising a peel seal joined to said first and third flanges along
their length.
15. The reclosable package as recited in claim 12, further
comprising a line of weakness formed in a portion of said first
panel that connects the respective portions of said first panel
that are joined to said first and third flanges.
16. The reclosable package as recited in claim 15, further
comprising a racetrack-shaped zone in which said first panel is
joined to said first and third flanges by means of sealant material
having a melting point lower than the melting point of the zipper
material.
17. The reclosable package as recited in claim 16, wherein each of
said first and second zipper end seals extends from an elevation
lower than said first and second closure profiles to an elevation
higher than a top edge of said first flange, and overlaps a
respective portion of said racetrack-shaped zone of joinder.
18. A reclosable package comprising: a zipper comprising first and
second zipper strips that have respective portions fused together
in first and second zipper end seals, said first zipper strip
comprising a length of a first closure profile and first and second
flanges extending in opposite directions and connected to said
first closure profile, respective portions of said first and second
flanges being flattened within the boundaries of said first and
second zipper end seals, and said second zipper strip comprising a
length of a second closure profile interlockable with said first
closure profile and a third flange connected to said second closure
profile, respective portions of said third flange being flattened
within the boundaries of said first and second zipper end seals,
said first and second zipper end seals respectively comprising
first and second transition areas disposed and connected to
opposite ends of said first and second closure profiles, and first
and second substantially flat portions that respectively border
said first and second transition areas on three sides thereof, said
first transition area comprising first sections of said first and
second closure profiles that have been deformed and at least
partially fused together but not flattened, and said second
transition area comprising second sections of said first and second
closure profiles that have been deformed and at least partially
fused together but not flattened, wherein third and fourth sections
of said first and second closure profiles that are respectively
adjacent said first and second sections form channels therebetween,
said channels within said third section being either sealed at one
end thereof by said first transition area or communicating with
channels formed by said first section that are sealed except where
they communicate with said channels formed by said third section,
and said channels within said fourth section being either sealed at
one end thereof by said second transition area or communicating
with channels formed by said second section that are sealed except
where they communicate with said channels formed by said fourth
section, said third flange being longer than said first flange and
extending beyond said first and second zipper end seals in an
elevational direction; and a receptacle comprising top and bottom
seals, a first panel connected to and extending between said top
and bottom seals, and a second panel connected to and extending
between said top and bottom seals, said first and second panels
bounding an interior volume of said receptacle, wherein each of
said first through third flanges is joined to said first panel and
not joined to said second panel.
19. A method of manufacture comprising the following steps: (a)
interlocking first and second zipper strips of a plastic zipper
tape, said first zipper strip comprising a first closure profile
and first and second flange extending from said first closure
profile in opposite directions, said second zipper strip comprising
a second closure profile and a third flange extending further from
said second closure profile than said first flange extends from
said first closure profile, said first and second closure profiles
in combination comprising at least three projecting elements; (b)
applying heat and pressure or ultrasonic vibrations and pressure in
first and second zones of said interlocked zipper strips, each of
said first and second zones extending from an elevation lower than
said first and second closure profiles to an elevation higher than
a top edge of said first flange, and having a predetermined
dimension in first and second areas of overlap with said
interlocked first and second closure profiles, whereby said first
and second closure profiles are flattened in first and second
sections having a length equal to said predetermined dimension, the
midpoints of said first and second sections being separated by one
zipper length, said first and third flanges are flattened at least
in respective areas directly above said first and second sections
of said first and second closure profiles, and said second flange
is flattened at least in respective areas directly below said first
and second sections of said first and second closure profiles; (c)
before step (b) is performed, applying heat and pressure or
ultrasonic vibrations and pressure in first and second transition
regions having intermediate portions that will be respectively
overlapped by said first and second zones in step (b), heat and
pressure or ultrasonic vibrations and pressure being applied to an
extent that upon completion of step (c), the projecting elements of
said first and second closure profiles that are furthest apart from
each other will become fused to respective portions of the other
zipper strip in said first and second transition regions, and said
first and second closure profiles will be heated but not flattened
in said first and second transition regions, wherein upon
completion of steps (b) and (c), said unflattened portions of said
first and second closure profiles in said first transition region
form first and second transition areas on opposite sides of a first
flattened section of said first and second closure profiles, and
said unflattened portions of said first and second closure profiles
in said second transition region form third and fourth transition
areas on opposite sides of a second flattened section of said first
and second closure profiles; (d) after step (b) has been performed,
applying pressure in said first and second transition regions to an
extent that surface irregularities formed on said first through
third flanges during step (b) are flattened without flattening said
first through fourth transition areas; and (e) cutting said first
and second zipper strips along first and second lines that
respectively intersect said first and second zones to create an
individual zipper.
20. The method as recited in claim 19, further comprising the
following step: (f) attaching said individual to a web of packaging
material in a transverse direction, wherein steps (a) through (f)
are repeated to form a zipper-carrying web having a multiplicity of
zippers attached thereto, said zippers being spaced apart at
regular intervals along the length of said web.
21. The method as recited in claim 20, further comprising the steps
of forming, filling and sealing said zipper-carrying web on a
form-fill-seal machine to make filled packages.
Description
BACKGROUND OF THE INVENTION
[0001] This invention generally relates to flexible containers,
such as pouches, bags or other packages, having a reclosable
plastic zipper. In particular, the invention relates to reclosable
bags, pouches or other packages for containing vacuum, pressure or
liquid.
[0002] To ensure hermeticity or airtightness, packagers have
typically sealed their flexible containers to an extent that they
are not reclosable after the seal is broken. Many flexible
containers that were reclosable typically did not retain the
desired vacuum, pressure or liquid containment feature that existed
prior to the container being opened for the first time.
[0003] In many different applications, it is desirable to provide a
reclosable container that, under normal or expected conditions of
usage, will not leak fluid when the zipper is reclosed. Such a
container should maintain a leakproof condition even when there is
a large differential in pressure between the interior and exterior
of the container. As used herein, the term "leakproof" does not
mean free of leaks under all temperature/pressure conditions, but
rather free of leaks over a range of temperatures and pressures
expected to occur during normal usage of the reclosable
container.
[0004] One use for hermetically resealable containers is in the
field of food product packaging. After a package of food has been
opened and a portion of the food product removed, the remaining
food product can be stored by closing the reclosable feature and
then evacuating the interior space of the package via a fixture
that penetrates a package wall. It is highly desirable that such
packages, containing perishable food product in a vacuum, be
leakproof, i.e., hermetic. By preventing exposure to air, the life
span of the perishable food product can be extended.
[0005] In other situations, it is desirable to provide a reclosable
package capable of holding liquid without leaking during normal
usage when the zipper is reclosed. Preferably such a package would
be able to withstand a predetermined pressure differential
(interior/exterior) without liquid leaking out of the package.
[0006] In accordance with another product application, a reclosable
bag may be filled at ambient atmosphere instead of being evacuated.
If such a bag were placed under extremely low pressure, e.g., while
being air-lifted via a cargo plane having a depressurized cargo
bay, then a large differential in pressure would exist between the
interior and exterior of the bag. In this situation, the internal
pressure may be about 15 psi, while the external pressure is
negligible. It is desirable that the bag not develop a leak and
that the zipper not pop open under such conditions.
[0007] Many existing form-fill-seal (FFS) machines operate on bag
making film and do not incorporate equipment for attaching zipper
assemblies to the bag making film. Although zipper application
machines are available that can be coupled to the FFS machine to
provide the zipper application function, operators of FFS machines
who do not wish to purchase a zipper applicator require that bag
making film with pre-attached zippers be available for purchase.
This film can then be run through the FFS machine. Although the
packager may need to modify his FFS machine to handle bag making
film with pre-attached zippers, the major capital investment of a
zipper application system can be avoided.
[0008] There is a need for improvements in the construction of
hermetically resealable flexible containers that can withstand a
large pressure differential (internal versus external) without
leaking and that can be formed, filled and sealed without the FFS
machine needing to perform any zipper application step.
BRIEF DESCRIPTION OF THE INVENTION
[0009] Flexible containers that are hermetically resealable are
disclosed herein. The disclosed resealable containers are of a type
that comprises front and rear panels forming an interior volume
that is accessible by means of a resealable plastic zipper attached
to the front panel only. Each zipper comprises a pair of extruded
plastic zipper strips. The zipper strips are flattened and joined
to each other at the ends and are further joined to each other,
without substantial deformation of the closure profiles, in
respective transition areas substantially contiguous with the
flattened ends. These transition areas of zipper strip joinder
assist in providing a leakproof transition from the openable
section of the zipper to where the closure profiles have been fused
and flattened (i.e., crushed).
[0010] One aspect of the invention is a reclosable package
comprising: a zipper comprising first and second zipper strips that
have respective portions fused together in first and second zipper
end seals, the first zipper strip comprising a length of a first
closure profile having at least two projecting elements and first
and second flanges extending in opposite directions and connected
to the first closure profile, respective portions of the first and
second flanges being flattened within the boundaries of the first
and second zipper end seals, and the second zipper strip comprising
a length of a second closure profile having at least one projecting
element that fits between the at least two projecting elements of
the first closure profile and a third flange connected to the
second closure profile, respective portions of the third flange
being flattened within the boundaries of the first and second
zipper end seals, the first and second zipper end seals
respectively comprising first and second substantially flat
portions and first and second transition areas respectively
connected to the first and second substantially flat portions on
first, second and third sides, wherein along the first and third
sides of each of the first and second transition areas, each of the
two projecting elements of the first and second closure profiles
that are furthest apart from each other is fused to some portion of
the one of the first and second zipper strips of which the
respective one of the furthest-apart projecting elements does not
form a part; and wherein along a second side of and within each of
the first and second transition areas, the first and second closure
profiles are deformed and fused together but not flattened, the
respective ends of the fused material along the second side being
integrally connected to the fused material of the first and third
sides, respectively, the third flange being longer than the first
flange and extending beyond the first and second zipper end seals
in an elevational direction; and a receptacle comprising top and
bottom seals, a first panel connected to and extending between the
top and bottom seals, and a second panel connected to and extending
between the top and bottom seals, the first and second panels
bounding an interior volume of the receptacle, wherein each of the
first through third flanges is joined to the first panel and not
joined to the second panel.
[0011] Another aspect of the invention is a reclosable package
comprising: a zipper comprising first and second zipper strips that
have respective portions fused together in first and second zipper
end seals, the first zipper strip comprising a length of a first
closure profile and first and second flanges extending in opposite
directions and connected to the first closure profile, respective
portions of the first and second flanges being flattened within the
boundaries of the first and second zipper end seals, and the second
zipper strip comprising a length of a second closure profile
interlockable with the first closure profile and a third flange
connected to the second closure profile, respective portions of the
third flange being flattened within the boundaries of the first and
second zipper end seals, the first and second zipper end seals
respectively comprising first and second transition areas disposed
at opposite ends of the first and second closure profiles, and
first and second substantially flat portions that respectively
border the first and second transition areas on three sides
thereof, the first transition area comprising first sections of the
first and second closure profiles that have been deformed and at
least partially fused together but not flattened, and the second
transition area comprising second sections of the first and second
closure profiles that have been deformed and at least partially
fused together but not flattened, the third flange being longer
than the first flange and extending beyond the first and second
zipper end seals in an elevational direction; and a receptacle
comprising top and bottom seals, a first panel connected to and
extending between the top and bottom seals, and a second panel
connected to and extending between the top and bottom seals, the
first and second panels bounding an interior volume of the
receptacle, wherein each of the first through third flanges is
joined to the first panel and not joined to the second panel.
[0012] A further aspect of the invention is a reclosable package
comprising: a zipper comprising first and second zipper strips that
have respective portions fused together in first and second zipper
end seals, the first zipper strip comprising a length of a first
closure profile and first and second flanges extending in opposite
directions and connected to the first closure profile, respective
portions of the first and second flanges being flattened within the
boundaries of the first and second zipper end seals, and the second
zipper strip comprising a length of a second closure profile
interlockable with the first closure profile and a third flange
connected to the second closure profile, respective portions of the
third flange being flattened within the boundaries of the first and
second zipper end seals, the first and second zipper end seals
respectively comprising first and second transition areas disposed
and connected to opposite ends of the first and second closure
profiles, and first and second substantially flat portions that
respectively border the first and second transition areas on three
sides thereof, the first transition area comprising first sections
of the first and second closure profiles that have been deformed
and at least partially fused together but not flattened, and the
second transition area comprising second sections of the first and
second closure profiles that have been deformed and at least
partially fused together but not flattened, wherein third and
fourth sections of the first and second closure profiles that are
respectively adjacent the first and second sections form channels
therebetween, the channels within the third section being either
sealed at one end thereof by the first transition area or
communicating with channels formed by the first section that are
sealed except where they communicate with the channels formed by
the third section, and the channels within the fourth section being
either sealed at one end thereof by the second transition area or
communicating with channels formed by the second section that are
sealed except where they communicate with the channels formed by
the fourth section, the third flange being longer than the first
flange and extending beyond the first and second zipper end seals
in an elevational direction; and a receptacle comprising top and
bottom seals, a first panel connected to and extending between the
top and bottom seals, and a second panel connected to and extending
between the top and bottom seals, the first and second panels
bounding an interior volume of the receptacle, wherein each of the
first through third flanges is joined to the first panel and not
joined to the second panel.
[0013] Yet another aspect of the invention is a method of
manufacture comprising the following steps: (a) interlocking first
and second zipper strips of a plastic zipper tape, the first zipper
strip comprising a first closure profile and first and second
flange extending from the first closure profile in opposite
directions, the second zipper strip comprising a second closure
profile and a third flange extending further from the second
closure profile than the first flange extends from the first
closure profile, the first and second closure profiles in
combination comprising at least three projecting elements; (b)
applying heat and pressure or ultrasonic vibrations and pressure in
first and second zones of the interlocked zipper strips, each of
the first and second zones extending from an elevation lower than
the first and second closure profiles to an elevation higher than a
top edge of the first flange, and having a predetermined dimension
in first and second areas of overlap with the interlocked first and
second closure profiles, whereby the first and second closure
profiles are flattened in first and second sections having a length
equal to the predetermined dimension, the midpoints of the first
and second sections being separated by one zipper length, the first
and third flanges are flattened at least in respective areas
directly above the first and second sections of the first and
second closure profiles, and the second flange is flattened at
least in respective areas directly below the first and second
sections of the first and second closure profiles; (c) before step
(b) is performed, applying heat and pressure or ultrasonic
vibrations and pressure in first and second transition regions
having intermediate portions that will be respectively overlapped
by the first and second zones in step (b), heat and pressure or
ultrasonic vibrations and pressure being applied to an extent that
upon completion of step (c), the projecting elements of the first
and second closure profiles that are furthest apart from each other
will become fused to respective portions of the other zipper strip
in the first and second transition regions, and the first and
second closure profiles will be heated but not flattened in the
first and second transition regions, wherein upon completion of
steps (b) and (c), the unflattened portions of the first and second
closure profiles in the first transition region form first and
second transition areas on opposite sides of a first flattened
section of the first and second closure profiles, and the
unflattened portions of the first and second closure profiles in
the second transition region form third and fourth transition areas
on opposite sides of a second flattened section of the first and
second closure profiles; (d) after step (b) has been performed,
applying pressure in the first and second transition regions to an
extent that surface irregularities formed on the first through
third flanges during step (b) are flattened without flattening the
first through fourth transition areas; and (e) cutting the first
and second zipper strips along first and second lines that
respectively intersect the first and second zones to create an
individual zipper.
[0014] Other aspects of the invention are disclosed and claimed
below.
BRIEF DESCRIPTION OF THE DRAWINGS
[0015] FIG. 1 is a drawing showing a schematic representation of
the cross section of a reclosable pouch or bag for vacuum, pressure
or liquid containment in accordance with one embodiment of the
invention.
[0016] FIG. 2 is a drawing showing a cross-sectional view of a
zipper that is suitable for use as a containment zipper in pouches
or bags of the type schematically depicted in FIG. 1.
[0017] FIG. 3 is a drawing showing in detail the closure profiles
of the zipper depicted in FIG. 2.
[0018] FIG. 4 is a drawing showing an isometric view of various
stations in a machine that is set up to perform operations in a
predetermined sequence in accordance with one method of
manufacture.
[0019] FIG. 5 is a drawing showing an isometric view of a grooved
bar suitable for heating and pressing a portion of a zipper without
flattening the closure profiles.
[0020] FIG. 6 is a drawing showing an isometric view of a grooved
bar suitable for flattening some portions of a zipper while
providing clearance for portions of the closure profiles not to be
flattened.
[0021] FIG. 7 is a drawing showing a stage in the manufacture of
the reclosable pouch or bag depicted in FIG. 1.
[0022] FIG. 8 is a drawing showing (on an enlarged scale) a front
view of a portion of a plastic zipper tape, having the cross
section shown in FIG. 2, that has been formed into a zipper end
seal structure. That structure can be bisected to form zipper end
seals of respective zippers suitable for incorporation in pouches
or bags of the type depicted in FIGS. 1 and 9. The dashed line
indicates the cut line.
[0023] FIG. 9 is a drawing showing a front view of the reclosable
pouch or bag depicted in FIG. 1 and having a zipper cut from the
zipper tape shown in FIG. 8.
[0024] FIG. 10 is a drawing showing an isometric view of portions
of a conventional vertical form-fill-seal machine suitable for
making pouches or bags of the type depicted in FIGS. 1 and 9.
[0025] It should be appreciated that the elements depicted in the
various drawings are not drawn to scale (except for FIG. 3, which
is based on a shadowgraph of an actual sample). In particular, for
purposes of illustration, the containment zipper has been shown out
of proportion (i.e., enlarged relative to the bag) in FIGS. 1 and
9.
[0026] Reference will now be made to the drawings in which similar
elements in different drawings bear the same reference
numerals.
DETAILED DESCRIPTION OF THE INVENTION
[0027] The present invention is directed to hermetically resealable
pouches or bags having an interior volume bounded by front and rear
panels, with a containment zipper attached to the front panel only.
In accordance with the embodiments disclosed herein, the
containment zipper has three flanges joined to the front panel only
of the completed reclosable pouch or bag. The zipper strips are
flattened and joined to each other at the ends and are further
joined to each other, without substantial deformation of the
closure profiles, in respective transition areas substantially
contiguous with the flattened ends. These transition areas of
zipper strip joinder assist in providing a leakproof transition
from the openable section of the zipper to where the closure
profiles have been fused and flattened (i.e., crushed).
[0028] With the ends of the zipper sealed using the techniques
disclosed hereinafter, the bag or pouch with front panel
containment zipper can be rendered suitable for containing vacuum,
pressure or liquid without leaking, even after the bag or pouch has
been opened and reclosed. By sealing the zipper to the front panel
instead of to both panels, the zipper will be exposed to less
stress under pressure. More specifically, by placing the zipper on
the front panel, forces due to internal pressure will act
perpendicularly to the zipper and all in one direction. With all
the force acting on the zipper in one direction, resistance to
opening will be maximized. The front panel design is also effective
in transferring the stresses of the internal pressure to the film
and away from the zipper. Higher internal pressures can be
accommodated to the point where the package film fails before the
zipper closure fails.
[0029] Further, in order to produce a reclosable pouch, bag or
package that will contain vacuum, pressure and/or liquids, it was
determined that there should be hard and intimate contact between
the closure profiles when the zipper is closed. More specifically,
it was determined that, in order to ensure that the zipper performs
its containment function in an acceptable manner, the percentage of
the area of intimate contact between closure profiles should lie
within a predetermined range. As used herein, the term "intimate
contact", in the context of a close zipper, means those portions of
the area at the interface of the interlocked closure profiles that
do not show any clearance between the respective closure profile
elements, such as hooked elements and posts or backup elements,
which viewed under a microscope. The areas without clearance can be
displayed by cutting the zipper with a razor blade and placing the
cross section under magnification. A magnified image of the closure
profiles (i.e., a so-called "shadowgraph") is produced, and then
the portions of the profiles that display intimate contact can be
marked on the image.
[0030] The minimum and maximum intimate contact area may be
expressed as percentage, whereby the area of lineal contact is
divided by the total available lineal surface of one profile. It
was determined that the minimum percentage of intimate contact area
that would still enable the zipper to perform satisfactorily as a
containment zipper was 33%, whereas the maximum percentage of
intimate contact area that would still enable the zipper to open
and reclose was 76%. It is believed that any zipper having an
intimate contact area percentage in the range of 33 to 76% can be
effectively placed in a reclosable package that will contain
vacuum, pressure and/or liquid during normal usage. Once a
containment zipper has been selected, the package designer must
then select a proper film strength and film seal integrity for the
specific application.
[0031] In addition, the respective closure profiles of the zipper
should have the same shape and configuration of elements, so that
thermoplastic zipper material is substantially symmetrically and
evenly distributed across the interlocked profiles. This will
facilitate the formation of zipper end stomps or joints having flat
surfaces and constant thickness.
[0032] If the minimum design criteria for the closure profiles are
met, the reclosable package will only be limited by the material
strength of the package components, i.e., the web material, the
web-to-web and web-to-zipper seals, and the zipper material.
[0033] Many different types of zippers are suitable for use as
containment zippers. In accordance with various embodiments
disclosed hereinafter, a containment zipper is incorporated into a
pouch or bag in such a way that the pouch or bag is able to
withstand a large pressure differential between the interior and
the exterior of the pouch or bag without leaking or popping open.
Alternatively, the pouch or bag is suitable for containing liquid
without leaking or popping open under the expected conditions of
normal usage.
[0034] A reclosable pouch or bag in accordance with one embodiment
of the invention is schematically represented in cross section in
FIG. 1. The pouch or bag comprises a receptacle 2 with a
three-flange containment zipper installed on the front panel 2a of
the bag. A top seal 20 joins respective marginal portions of the
front and rear panels 2a and 2b at the top of the bag; a bottom
seal 21 joins respective marginal portions of the front and rear
panels 2a and 2b at the bottom of the bag.
[0035] Still referring to FIG. 1, one strip of the containment
zipper comprises a closure profile 10 and upper and lower flanges
12 and 14 extending in opposite directions from closure profile 10.
The other zipper strip comprises a closure profile 16 and an upper
flange 18 having a length substantially greater than upper flange
12. The lower flange 14 of zipper strip 6 is heat sealed to the
front panel 2a in a band-shaped zone 24 that extends the length of
the zipper strip. The upper flanges 12 and 18 are heat sealed to
the front panel 2a in a racetrack-shaped zone 26, best seen in FIG.
9. In the sectional view of FIG. 1, items 26a and 26b represent the
straight portions of the racetrack seal, the straight portion 26b
being a zone where upper flange 18 is joined to the front panel 2a,
while the straight portion 26a is a zone where upper flange 12 is
joined to the front panel 2a. The portion of the front panel 2a
that is bounded by the racetrack seal 26 is provided with a line
118 of weakened tear resistance, e.g., a line of spaced
perforations or a laser scoreline, which extends generally parallel
to the zipper. The tear line 118 is best seen in FIG. 9. After the
consumer tears open the front panel along the tear line 118, access
to the zipper is blocked by a peel seal 36, which joins opposing
portions of the upper flanges 12 and 18 along the length of the
zipper. To gain access to the contents of the package, the consumer
must peel open the peel seal 36 and then pull apart the zipper
strips 6 and 8.
[0036] The structure of the containment zipper attached to front
panel 2a is only schematically represented in FIG. 1. The structure
of an exemplary containment zipper, suitable for incorporation in
the bag seen in FIG. 1, is shown in detail in FIG. 2. The intimate
contact area between the respective closure profiles lies within
the aforementioned percentage range that is suitable for use as a
containment zipper. One zipper strip 6 comprises a closure profile
10 and upper and lower flanges 12 and 14 extending in opposite
directions therefrom. The upper flange 12 is longer than the lower
flange 14 in the elevational direction. The closure profile 10
comprises a pair of monohook elements and a post or backup element
devoid of a hook. A portion of the outer surface of upper flange 12
is coated with a sealant layer 30 to facilitate heat sealing of the
upper flange 12 to the front panel 2a. The lower flange 14 has a
similar sealant layer 28 on its outer surface. The other zipper
strip 8 comprises a closure profile 16 and an upper flange 18
having a length substantially greater than the length of upper
flange 12. Zipper strip 8 has no lower flange. The closure profile
16 also comprises a pair of monohook elements and a post or backup
element devoid of a hook. In this particular containment zipper
embodiment, the respective posts are the profile elements that are
furthest apart from each other. A portion of the inner surface of
upper flange 18 is coated with a sealant layer 32 to facilitate
heat sealing of the upper flange 18 to the front panel.
[0037] The zipper shown in FIG. 2 further comprises a layer 36a of
peelable sealing material applied on the interior surface of upper
flange 12 of zipper strip 6 and a layer 36b of peelable sealing
material applied on the interior surface of upper flange 18 of
zipper strip 8. The layers of peelable sealing material have the
same width and extend the full length of the zipper strips, and are
placed in mutual opposition to each other. These layers are pressed
together and heat-activated to form the peel seal 36 seen in FIG.
1.
[0038] The three-flange zipper seen in FIG. 2 is shown on an
enlarged scale in FIG. 3. The closure profile 16 comprises three
profiled closure elements 42, 44 and 46 projecting from a base 38,
the upper flange 18 (shown only in part) having an end integrally
formed with base 38. Elements 44 and 46 are monohook elements,
while element 42 is a post having no hook. Similarly, the closure
profile 10 comprises three profiled closure elements 48, 50 and 52
projecting from a base 40, the upper flange 12 and the short
extension 14 having respective ends integrally formed with base 40.
Elements 50 and 52 are monohook elements, while element 48 is a
post having no hook. When the closure profiles are fully
interlocked, as shown in FIG. 3, monohook element 52 of closure
profile 10 is disposed in a recess defined by and is in contact
with post 42 and monohook element 44 of closure profile 16; the
monohook element 44 of closure profile 16 is disposed in a recess
defined by and is in contact with monohook elements 50 and 52 of
closure profile 10; and so forth. The intimate contact area between
the respective closure profiles lies within the aforementioned
percentage range that is suitable for use as a containment
zipper.
[0039] Before pouches or bags of the type shown in FIG. 1 can be
made on an FFS machine, the thermoplastic zipper material must be
processed into containment zippers suitable for transverse
attachment to a web of packaging film. Zipper material is typically
supplied in the form of a great length of zipper tape comprising
interlocked zipper strips unwound from a reel or spool. The zipper
tape will become many zippers of equal length.
[0040] In accordance with the embodiments disclosed herein, the
zipper tape is subjected to heat and pressure and/or ultrasonic
vibrations and pressure in so-called "transition regions" spaced
along the zipper tape at regular intervals, one transition region
per length of zipper tape equal to one zipper. A system for forming
such transition regions on a zipper tape is schematically depicted
in FIG. 4.
[0041] As seen in FIG. 4, the zipper processing system comprises a
plurality of stations, each of which performs work on each
transition region, the stations being spaced along an automated
production line at regular intervals. Each transition region on the
zipper tape 4' must pass in succession through the stages depicted
in FIG. 4. The direction of zipper advancement is indicated by the
arrow. FIG. 4 shows the case where the spacing of the work stations
is constant, i.e., one station per zipper length, meaning that
during each cycle the zipper tape 4' is indexed forward by a
distance equal to one zipper length, successive stations operating
on the same transition region during successive dwell times.
However, the person skilled in the art of setting up such equipment
for processing plastic zipper tape will recognize that the distance
between the centerlines of the work stations may be varied, so long
as each such distance is one or multiple zipper lengths.
[0042] At station 90, a transition region on zipper tape 4' is
pressed between a first set of mutually opposing heated grooved
bars (only one of which is visible in FIG. 4, the other being
underneath the zipper tape). Each grooved bar at station 90
preferably has the same structure. FIG. 5 shows an exemplary
grooved bar 70 having coplanar flat rectangular surfaces 78 and 82,
with a groove 74 therebetween. In this example, the groove 74 has a
trapezoidal cross-sectional shape; however, the shape of the groove
may be varied as a function of the outer profile of the particular
zipper being employed.
[0043] Two heated grooved bars of the type shown in FIG. 5 are
arranged in mutual opposition at station 90. FIG. 7 shows two such
grooved bars 70 and 72 in their respective positions at the start
of retraction. For the purpose of illustration, gaps have been
exaggerated. Respective sections of closure profiles 10 and 16 are
captured between the mutually confronting grooves 74 and 76 of bars
70 and 72 when they are extended. The grooves may be designed to
apply a gentle force to the profiles without substantial
deformation and, in particular, without flattening the closure
profiles. The mutually confronting flat surfaces 82 and 84 of the
grooved bars press intervening portions of the upper flanges
together with a temperature sufficient to melt the upper flanges
together, forming fused upper flanges 54. The height of each
grooved bar is generally coextensive with the transition region 110
seen in FIG. 8, which shows a processed portion of the zipper tape.
More precisely, the transition region comprises the cross-hatched
area in FIG. 8 as well as the areas 114, which are not cross
hatched. These areas form a rectangular transition region 110. As
indicated by the hatching in FIG. 8, the grooved bars at station 90
are placed so that one edge of the grooved bars is disposed lower
than the closure profiles, while the opposing edge is disposed at
the level of the edge of upper flange 12.
[0044] The grooved bars at station 90 may be designed to apply heat
and light pressure to the flanges in the transition region 110 (see
FIG. 8) while clearance is provided for the section of the closure
profiles within the transition region, which section may be shaped
but not flattened. The temperature of the grooved bars is
sufficiently high to melt the upper flanges during the allotted
dwell time. The portions of the flanges trapped between the flat
faces of the grooved bars are melted, while the portions of the
closure profiles trapped between the opposing grooves of the
grooved bars are shaped and partially fused, but not flattened. In
particular, it is desirable that the projecting elements of the
closure profiles which are furthest away from each other be melted
and later fused to opposing melted portions of the other zipper
strip.
[0045] Such a state is depicted in FIG. 7, which depicts a cross
section of a portion of the closure profiles in the transition
region after operation of station 90. FIG. 7 shows two areas 56 and
58 where the zipper strips 6 and 8 have been fused or melded
together. Although the separate components are no longer visible in
FIG. 7, each fused region 56 and 58 represents a region where a
post and an adjoining portion of one zipper strip has been fused
with confronting portions of the other zipper strip. For example,
the fused region 58 seen in FIG. 7 was formed by fusing portions of
post 48 and flanges 12 and 18 seen in FIG. 3. Similarly, the fused
region 56 seen in FIG. 7 was formed by fusing portions of post 42
and flange 14 seen in FIG. 3. FIG. 7 shows that the hooks of the
monohook elements of zipper strips 6 and 8 have not been fused
together in the area where the section was taken. In this
particular example, the spaces between undeformed portions of the
closure profiles form a plurality of channels 60, 62, 64 and 66
that run lengthwise along the zipper. (Portions of the undeformed
closure profiles in the transition region will in turn become
respective transition areas, as explained hereinafter.) These
channels will not produce leakage through the end of the zipper
because they will be closed off during the subsequent profile
flattening operation.
[0046] However, in the alternative, the transition areas may be
formed in a manner such that the hooks of the monohook elements are
fused together and there are no channels such as those depicted in
FIG. 7.
[0047] If necessary, the formation of transition areas may involve
one or more operations performed by respective sets of heated
grooved bars located at different stations in the machine. The
temperatures and pressure at those stations may be varied as
required. For example, the state of fusion depicted in FIG. 7 may
be attained by station 90 alone or in conjunction with a similarly
constructed station downstream from station 90.
[0048] At the start of the next work cycle, the zipper tape 4' is
indexed forward until the same zipper section that was pressed at
station 90 arrives at ultrasonic welding 92. Station 92 comprises
an ultrasonic horn (seen in FIG. 4) and an opposing anvil (not
visible in FIG. 4 because it is underneath the zipper tape 4'. The
horn and anvil may each comprise a bar constructed as seen in FIG.
6. The bar 98 may have the same size and shape as bar 70 seen in
FIG. 5, except that instead of a groove extending across the full
width of the bar, the bar 98 has two grooves 103 and 105, separated
by a neck portion 104. The flat surface of neck 104 is coplanar
with and connected to flat faces 100 and 102, which are disposed on
opposite sides of the grooves. The width of the neck portion 104
must be less than (e.g., 2/3) the width of the grooved bars at
station 90.
[0049] Two bars of the type shown in FIG. 6 can be arranged in
mutual opposition at station 92, one of the bars being coupled to
an ultrasonic transducer (not shown) that converts electrical
current into vibrations. The horn and anvil are extended while the
horn is activated. In their extended positions, the horn and anvil
will impinge upon the transition region 110 seen in FIG. 8. As the
flat surfaces of the horn press intervening portions of the zipper
tape 4' against the flat surfaces of the anvil, those intervening
portions are melted and flattened, with some of the material being
displaced sideways. At the same time, the portions of the closure
profiles that lie between the mutually opposing grooves are not
flattened. These unflattened portions of the closure profiles will
become transition areas 114 as depicted in FIG. 8. The transition
areas 114 are separated by an area 112 in which the closure
profiles have been flattened.
[0050] If further flattening of the flanges above and below the
transition areas is not desired, a horn and an anvil having
rectangular faces without grooves and having a width equal to the
width of neck portion 104, seen in FIG. 6, could be used to flatten
the zipper tape 4' in an intermediate portion of the transition
region 110, thereby flattening the closure profiles between areas
114 seen in FIG. 8.
[0051] Welding and sealing of thermoplastic material by ultrasonic
vibrations is an established process. A typical ultrasonic welding
apparatus in which a workpiece is fed through an ultrasonic weld
station comprises an anvil and an oppositely disposed resonant
horn. The frontal surface of the horn and the anvil are urged
toward mutual engagement, for coupling the ultrasonic vibrations
from the activated horn into the thermoplastic material of the
workpiece, thereby effecting ultrasonic welding. The horn is
energized from a power supply that provides electrical
high-frequency power at a predetermined ultrasonic frequency to an
electro-acoustic transducer, which, in turn, provides mechanical
vibrations at that frequency to a booster or coupling horn for
coupling these vibrations to the horn.
[0052] Alternatively, station 92 could employ heated bars having
the same size and shape seen FIG. 6, thereby avoiding capital
investment in ultrasonic welding equipment. In that event, the
portions of the closure profiles intervening between the necked
portions of the heated bars would be thermally crushed.
[0053] At the start of the next work cycle, the zipper tape 4' is
again indexed forward until the same zipper section that was
partially flattened at station 92 arrives at station 94, where it
is pressed between a set of mutually opposing heated grooved bars
(only one of which is visible in FIG. 4). The grooved bars at
station 94 may be arranged and configured substantially identically
to the grooved bars at station 90, but are heated to a lower
temperature and apply a higher pressure than were in effect for the
grooved bars at station 90. During operation of the grooved bars at
station 94, any dams of plastic created by the ultrasonic welding
apparatus on the flanges of the zipper are flattened. Again, the
portions of the closure profiles trapped between the opposing
grooves of the grooved bars at station 94 (namely, the transition
areas 114 seen in FIG. 8) are not flattened. The area contacted by
the grooved bars at station 94 approximately overlies the area that
was previously contacted by grooved bars at station 90 (namely, the
transition region 110 seen in FIG. 8). During the application of
heat and pressure by the third set of grooved bars, the transition
areas will reside in the gap between the mutually confronting
grooves on the bars, and thus will not be flattened.
[0054] Alternatively, the work done at stations 90 and 94 could be
accomplished using ultrasonic vibrations instead of heated bars.
Or, alternatively, the work done at station 92 could be
accomplished using heated bars instead of ultrasonic
vibrations.
[0055] In accordance with the preferred method of manufacture, the
heated areas are then cooled by being placed in contact with
surfaces of chilled or unheated bars. The zipper tape 4' is again
indexed forward until the same zipper section that was pressed at
station 94 arrives at the cooling station 96, where it is pressed
between a set of mutually opposing chilled or unheated grooved bars
(only one of which is visible in FIG. 4). The grooved bars at
station 96 may be arranged and configured substantially identically
to the grooved bars at station 92 (one of which is shown in FIG.
6). Again, the portions of the closure profiles trapped between the
opposing grooves of the grooved bars at station 96 are not
flattened. The area contacted by the grooved bars at station 96
approximately overlies the area that was previously contacted by
grooved bars at station 92. During the application of pressure by
the chilled or unheated bars, the transition areas will reside in
the gap between the mutually confronting grooves on the bars, and
thus will not be flattened. The grooved bars at station 96 act as
heat sinks, extracting heat from the previously heated
thermoplastic material. The material thus cooled would include the
upper and lower flanges in the heat-treated zipper section as well
as the transition areas. The cooling stations achieve the desired
final formation of the transition areas and adjacent areas.
[0056] The transition area between crushed and non-crushed closure
profiles needs to be correctly formed for containment applications.
To successfully form a tight transition area, the zipper processing
machine can be set up with grooved bars that are specially designed
for the particular zipper being employed. Although FIG. 4 shows two
stations 90 and 94 having heated grooved bars for softening and/or
melting portions of the zipper profiles and flanges, the number of
stations used to form the leakproof zipper end seal will not be the
same for all machines and zipper structures. Moreover, the
temperature and pressure settings for the heated grooved bars will
be based on different line speeds, available dwell times, zipper
structures and machine types.
[0057] The result of the foregoing operations is seen in FIG. 8,
which shows a processed portion of a zipper tape having the cross
section generally shown in FIG. 2. Each transition area 114,
comprising respective sections of the closure profiles that are at
least partly joined together, is connected at one end to an
uncrushed portion of the closure profiles 8, 10 and is
substantially contiguous at the other end with the flattened area
112. The areas above and below the transition areas 114 and the
flattened area 112 form a flattened area generally indicated by
cross hatching in FIG. 8. The zipper tape will later be cut along
dashed line 111 to form respective zipper end seals for respective
individual zippers.
[0058] During the zipper formation by the apparatus depicted in
FIG. 4, leakproof transition regions are formed. Thereafter, the
zipper tape can be fed directly to a zipper applicator on site,
which attaches successive zipper-length zipper tape segments to a
web of packaging film, each zipper being oriented transverse to the
lengthwise direction of the web. Alternatively, the zipper tape can
be rolled up and transported for feeding into a zipper applicator
located at a different site. Zipper application equipment for
attaching three flanges of a three-flange front panel zipper to a
web of packaging film is well known. A zipper guide is used to
guide a distal portion of the zipper tape into a transverse
position overlying the web. Then the distal portion is cut off and
heat sealed to the web using two sets of mechanically linked
sealing bars, at least one sealing bar of each set being heated. If
the zipper was not produced with a pre-activated peel seal, the
peel seal would be formed at this time in conjunction with the
zipper-to-film sealing operation. The sealing bars of the set that
makes zone of web-zipper joinder 24 (see FIG. 9) are straight; the
sealing bars of the set that makes zone of web-zipper joinder 26
(see FIG. 9) are racetrack shaped, i.e., two semicircles connected
by two straight lines. A tear line 118 (e.g., a line of spaced
perforations) is formed in the web before zipper application.
[0059] The web with attached containment zippers can be fed
directly to an FFS machine (vertical or horizontal) on site or, in
the alternative, the web with attached containment zippers can be
rolled up and transported for feeding into an FFS machine located
at a different site.
[0060] In accordance with one embodiment of the invention, the web
2 of bag making film with zippers 4 attached at intervals
therealong is fed to a VFFS machine 120 (shown in FIG. 10). The web
2 is fed downwardly over a forming collar 126 and is folded around
a filling tube 122. The edges of the web are brought together and
pressed by a pair of rollers 124a and 124b. These edges of the web
are then sealed together by a pair of opposing longitudinal sealing
bars 128a and 128b to form a longitudinal fin seal 25 (behind the
bag in FIG. 9). Contents are then dropped through the tube 122 into
the bag 132 that is currently being made. At the time of filling,
bag 132 has a bottom seal 22 that was formed when the immediately
preceding bag 136 was completed by making a top seal 20. After
filling, the top of the instant bag 132 and the bottom of the next
succeeding bag 134 are sealed by the action of cross sealing jaws
130a and 130b. Each cross sealing jaw 130a and 130b comprises a
respective pair of mutually parallel sealing bars, the sealing bars
of jaw 130a being aligned with and opposed to the respective
sealing bars of jaw 130b. Both cross sealing jaws 130a and 130b are
heated to a temperature that causes the front and rear panels to
seal together during a preset dwell time (controlled by a
programmable controller not shown) in their extended positions,
thereby forming a top seal 20 of the just-filled bag and a bottom
seal 22 of the immediately preceding unfilled package. The
temperature of the sealing bars is controlled by a programmable
heat controller (not shown). A knife (not shown in FIG. 10) is
incorporated in cross sealing jaw 130a, while a backing member (not
shown) for supporting the film during cutting is incorporated in
cross sealing jaw 130b. When the cross sealing jaws are in their
respective extended position, the opposing panels of web 2 are cut
by the knife. When the sealing jaws 130a and 130b are retracted,
the severed bag 136 will proceed to the next stage.
[0061] A completed package having a containment zipper attached to
the front panel only is shown in FIG. 9. Flange 14 is attached to
the front panel by means of heat seal 24; flanges 12 and 18 are
attached to the front panel by means of racetrack heat seal 26,
which is formed in part by portions of the sealant layers 30 and 32
on flanges 12 and 18. Access to the interior volume of the package
is through the portion of the front panel bounded by the racetrack
seal 26. A tear line 118 facilitates opening of that portion. The
containment zipper has zipper end seals comprising a respective
transition area 114 and the flat fused area (indicated by cross
hatching) that connects to the transition area 114 on three sides
thereof. Those fused areas include area 112 where the closure
profiles were flattened. The pre-activated peel seal 36 is disposed
between the tear line 118 and the closure profiles 10, 16.
[0062] While the invention has been described with reference to
various embodiments, it will be understood by those skilled in the
art that various changes may be made and equivalents may be
substituted for elements thereof without departing from the scope
of the invention. In addition, many modifications may be made to
adapt a particular situation to the teachings of the invention
without departing from the essential scope thereof. Therefore it is
intended that the invention not be limited to the particular
embodiment disclosed as the best mode contemplated for carrying out
this invention, but that the invention will include all embodiments
falling within the scope of the appended claims.
[0063] As used in the claims, the term "joined" means fused, welded
or heat sealed. As used in the claims, the term "package" means a
bag, pouch or other flexible container. As used in the claims, the
term "panel" includes, but is not limited to, a discrete piece of
web material, a portion of a folded piece of web material or two
portions of a folded piece of web material joined at a seam.
Further, in the absence of explicit language in any method claim
setting forth the order in which certain steps should be performed,
the method claims should not be construed to require that steps be
performed in the order in which they are recited.
* * * * *