Note : Les descriptions sont présentées dans la langue officielle dans laquelle elles ont été soumises.
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SYSTEM AND METHOD FOR FORMING AN INTEGRATED TRAY
FOR USE IN VACUUM PACKAGING
CLAIM OF PRIORITY
[0001] This application claims priority from U.S. Provisional Patent
Application No.
60/452,172, entitled "SEALABLE BAG HAVING AN INTEGRATED TRAY FOR USE IN
VACUUM PACKAGING," by Henry Wu, et al., filed March 5, 2003 (Attorney Docket
No. TILA-
01178US0); U.S. Provisional Patent Application No. 60/452,171, entitled
"METHOD FOR
MANUFACTURING A SEALABLE BAG HAVING AN INTEGRATED TRAY FOR USE IN
VACUUM PACKAGING," by Henry Wu, et al., filed March 5, 2003 (Attorney Docket
No. TILA-
01178US1 ); U.S. Patent Application No. 10l ,- entitled "SEALABLE BAG HAVING
AN
INTEGRATED TRAY FOR USE IN VACUUM PACKAGING," by Hongyu Wu, et al., filed
March 4, 2004 (Attorney Docket No. TILA-01178US2); and U.S. Patent Application
No.
10/ ,- entitled "METHOD FOR MANUFACTURING A SEALABLE BAG HAVING AN
INTEGRATED TRAY FOR USE IN VACUUM PACKAGING," by Hongyu Wu, et al., filed
March 4, 2004 (Attorney Docket No. TILA-01178US3).
CROSS-REFERENCE TO RELATED PATENT APPLICATIONS
[0002] This application incorporates by reference all of the following co-
pending
applications:
[0003] U.S. Provisional Patent Application No. 60/452,168, entitled "LIQUID-
TRAPPING BAG FOR USE IN VACUUM PACKAGING," by Henry Wu, et al., filed March 5,
2003 (Attorney Docket No. TILA-01177US0);
[0004] U.S. Provisional Patent Application No. 60/452,171, entitled "METHOD
FOR
MANUFACTURING A LIQUID-TRAPPING BAG FOR USE IN VACUUM PACKAGING," by
Henry Wu, et al., filed March 5, 2003 (Attorney Docket No. TILA-01177US1 );
[0005] U.S. Provisional PatentApplication No. 60/451,954, entitled "SEALABLE
BAG
HAVING AN INDICIA FOR USE IN VACUUM PACKAGING," by Henry Wu, et al., filed
March
5, 2003 (Attorney Docket No. TILA-01179US0);
[0006] U.S. Provisional Patent Application No. 60/451,948, entitled "METHOD
FOR
MANUFACTURING A SEALABLE BAG HAVING AN INDICIA FOR USE IN VACUUM
PACKAGING," by Henry Wu, et al., filed March 5, 2003 (Attorney Docket No. TILA-
01179US1 );
[0007] U.S. Provisional PatentApplication No.60/452,142, entitled "SEALABLE
BAG
HAVING AN INTEGRATED ZIPPER FOR USE IN VACUUM PACKAGING," by Henry Wu,
et al., filed March 5, 2003 (Attorney Docket No. TILA-01180US0);
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[0008] U.S. Provisional Patent Application No. 60/452,021, entitled "METHOD
FOR
MANUFACTURING A SEALABLE BAG HAVING AN INTEGRATED ZIPPER FOR USE IN
VACUUM PACKAGING," by Henry Wu, et al., filed March 5, 2003 (Attorney Docket
No. TILA-
01180US1 );
[0009] U.S. Provisional PatentApplication No. 60/451,955, entitled "SEALABLE
BAG
HAVING AN INTEGRATED VALVE STRUCTURE FOR USE IN VACUUM PACKAGING," by
Henry Wu, et al., filed March 5, 2003 (Attorney Docket No. TILA-01181 USO);
[0010] U.S. Provisional Patent Application No. 60/451,956, entitled "METHOD
FOR
MANUFACTURING A SEALABLE BAG HAVING AN INTEGRATED VALVE STRUCTURE
FOR USE IN VACUUM PACKAGING," by Henry Wu, et al., filed March 5, 2003
(Attorney
Docket No. TILA-01181 US1 );
[0011] U.S. Provisional PatentApplication No. 60/452,157, entitled "SEALABLE
BAG
HAVING AN INTEGRATED TIMER/SENSOR FOR USE IN VACUUM PACKAGING," by
Henry Wu, et al., filed March 5, 2003 (Attorney Docket No. TILA-01182US0);
[0012] U.S. Provisional Patent Application No. 60/452,139, entitled "METHOD
FOR
MANUFACTURING A SEALABLE BAG HAVING AN INTEGRATED TIMERISENSOR FOR
USE IN VACUUM PACKAGING," by Henry Wu, et al., filed March 5, 2003 (Attorney
Docket
No. TILA-01182US1 );
[0013] U.S. Patent Application No. 10/169,485, entitled "METHOD FOR
~ PREPARING AIR CHANNEL EQUIPPED FILM FOR USE IN VACUUM PACKAGE," filed
June 26, 2002;
[0014] U.S. Patent Application No. 10/ ,-, entitled "LIQUID-TRAPPING BAG
FOR USE IN VACUUM PACKAGING," by Hongyu Wu, et al., filed March 4, 2004
(Attorney
Docket No. TILA-01177US2);
[0015] U.S. Patent Application No. 10/-, , entitled "METHOD FOR
MANUFACTURING LIQUID-TRAPPING BAG FOR USE IN VACUUM PACKAGING," by
Hongyu Wu, et al., filed March 4, 2004 (Attorney Docket No. TILA-01177US3);
[0016] U.S. Patent Application No.10/ , , entitled "SEALABLE BAG HAVING
AN INDICIA FOR USE IN VACUUM PACKAGING," by Hongyu Wu, et al., filed March 4,
2004
(Attorney Docket No. TILA-01179US2);
[0017] U.S. Patent Application No. 10/ , , entitled "METHOD FOR
MANUFACTURING A SEALABLE BAG HAVING AN INDICIA FOR USE IN VACUUM
PACKAGING," by Hongyu Wu, et al., filed March 4, 2004 (Attorney Docket No.
TILA-
01179US3);
[0018] U.S. Patent Application No.10/ ,-, entitled,"SEALABLE BAG HAVING
AN INTEGRATED ZIPPER FOR USE IN VACUUM PACKAGING," by Hongyu Wu, et al.,
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filed March 4, 2004 (Attorney Docket No. TILA-01180US2);
[0019] U.S. Patent Application No. 10/ -, entitled, "METHOD FOR
MANUFACTURING A SEALABLE BAG HAVING AN INTEGRATED ZIPPER FOR USE IN
VACUUM PACK/~,GING," by Hongyu Wu, et al., filed March 4, 2004 (Attorney
Docket No.
TILA-01180US3);
[0020] U.S. Patent Application No.10/ ,-, entitled, "SEALABLE BAG HAVING
AN INTEGRATED VALVE STRUCTURE FOR USE IN VACUUM PACKAGING," by Hongyu
Wu, et al., filed March 4, 2004 (Attorney Docket No. TILA-01181 US2);
[0021] U.S. Patent Application No. 10/-, , entitled, "METHOD FOR
MANUFACTURING A SEALABLE BAG HAVING AN INTEGRATED VALVE STRUCTURE
FOR USE IN VACUUM PACKAGING," by Hongyu Wu, et al., filed March 4, 2004
(Attorney
Docket No. TILA-01181 US3);
[0022] U.S. Patent Application No.10/ -, entitled, "SEALABLE BAG HAVING
AN INTEGRATED TIMER/SENSOR FOR USE IN VACUUM PACKAGING," by Hongyu Wu,
et al., filed March 4, 2004 (Attorney Docket No. TILA-01182US2); and
[0023] U.S. Patent Application No. 10/ ,- entitled, "METHOD FOR
MANUFACTURING A SEALABLE BAG HAVING AN INTEGRATED TIMER/SENSOR FOR
USE IN VACUUM PACKAGING," by Hongyu Wu, et al., filed March 4, 2004 (Attorney
Docket
No. TILA-01182US3).
FIEL~ ~F THE 11~~9EI~TI~1~
[0024] The present invention relates to bags for use in vacuum packaging and
methods and devices for manufacturing bags for use in vacuum packaging.
BACKGROUN~
[0025] Methods and devices for preserving perishable foods such as fish and
meats,
processed foods, prepared meals, and left-overs, and non-perishable items are
widely known,
and widely varied. Foods are perishable because organisms such as bacteria,
fungus and
mold grow over time after a food container is opened and the food is left
exposed to the
atmosphere. Most methods and devices preserve food by protecting food from
organism-filled
air. A common method and device includes placing food into a gas-impermeable
plastic bag,
evacuating the air from the bag using suction from a vacuum pump or other
suction source,
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and tightly sealing the bag.
[0026] A bag for use in vacuum packaging can consist of a first panel and
second
panel, each panel consisting of a single layer of heat-sealable, plastic-based
film (for
example, polyethylene). The panels are sealed together along a substantial
portion of the
periphery of the panels by heat-sealing techniques so as to form an envelope.
Perishable
products, such as spoilable food, or other products are packed into the
envelope via the
unsealed portion through which air is subsequently evacuated. After perishable
products are
packed into the bag and air is evacuated from the inside of the bag, the
unsealed portion is
heated and pressed such that the panels adhere to each other, sealing the bag.
[0027] U.S. Pat. No. 2,778,173, incorporated herein by reference, discloses a
method for improving the evacuation of air from the bag by forming channels in
at least one
of the panels with the aid of embossing techniques. Air escapes from the bag
along the
channels during evacuation. The embossing forms a pattern of protuberances on
at least one
of the panels. The protuberances can be discrete pyramids, hemispheres, etc.,
and are
formed by pressing a panel using heated female and male dies. The first panel
is overlaid on
the second panel such that the protuberances from one panel face the opposite
panel. The
contacting peripheral edges of the panels are sealed to each other to form an
envelope
having an inlet at an unsealed portion of the periphery. The perishable or
other products are
packed into the envelope through the inlet, and the inlet is sealed.
Thereafter, an opening is
pierced in a part of the panel material that communicates with the channels,
air is removed
from the interior of the envelope through the channels and opening, and the
opening is
sealed. This type of bag requires two additional sealing steps after the
perishable or other
product is packed into the envelope. One further problem is that embossing
creates
impressions on the plastic such that indentations are formed on the opposite
side of the panel
[0028] To avoid additional sealing steps, a vacuum bag is formed having a
first
panel and a second panel consisting of laminated films. Each panel comprises a
heat-
sealable inner layer, a gas-impermeable outer layer, and optionally, one or
more intermediate
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layers. Such a bag is described in U.S. Pat. No. Re. 34,929, incorporated
herein by reference.
At least one film from at least one panel is embossed using an embossing mold
to form
protuberances and channels defined by the space between protuberances, so that
air is
readily evacuated from the vacuum bag.
5 [0029] U.S. Pat. No. 5,554,423, incorporated herein by reference, discloses
still
another bag usable in vacuum packaging. The bag consists of a first and second
panel, each
panel consisting of a gas-impermeable outer layer and a heat-sealable inner
layer. A plurality
of heat-sealable strand elements are heat bonded at regular intervals to the
inner layer of
either the first panel or the second panel. The spaces between strand elements
act as
channels for the evacuation of air. The strand elements are extruded from an
extrusion head
and heat bonded to the heat-sealable layer by use of pressure rolls. Separate
equipment is
required for producing strand elements, and a procedure of heat bonding a
plurality of strand
elements at regular intervals to the heat-sealable inner layer is complicated.
Also, various
shapes of pattern are hard to form using this process.
BRIEF ~ESCI<:IPTI~N ~F THE FIGURES
[0030] Further details of embodiments of the present invention are explained
with
the help of the attached drawings in which:
[0031] FIG. 1A is a perspective view of a method for manufacturing a vacuum
bag
in accordance with one embodiment of the present invention;
[0032] FIG. 1B is a side view of the method shown in FIG. 1A illustrating the
embossing method used in an embodiment of the present invention;
[0033] FIG. 1C is a close-up view of a portion of FIG. 1B;
[0034] FIG. 2A is a plan view of a panel in accordance with one embodiment of
the
present invention, manufactured by the process shown in FIG. 1A-1C;
[0035] FIG. 2B is a cross-section view of a panel in accordance with one
embodiment ofthe present invention, manufactured bythe process shown in FIG.1A-
1 C; and
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[0036] FIG. 3 is a perspective view of a vacuum bag in accordance with one
embodiment of the present invention.
DETAILED DESCRIPTION
[0037] FIGS. 1A-1C illustrate one embodiment of a method for manufacturing a
vacuum bag in accordance with the present invention. The vacuum bag comprises
a first
panel and a second panel, wherein each panel comprises a gas-impermeable base
layer 108
and a heat-sealable inner layer 106 with at least one panel having raised
walls for preventing
shifting of perishable or other product contained inside the vacuum bag. A
laminating roll 102
and a cooling roll 104 are arranged so that the heat-sealable inner layer 106
can be laminated
to the gas-impermeable base layer 108 as the melt-extruded resin is cooled. As
illustrated in
FIG. 1C, the gap between the laminating roll 102 and the cooling roll 104 can
be controlled
according to specifications (for example, thickness) of a panel for use in
vacuum packaging.
The temperature of the cooling roll 104 is maintained in a range such that the
melt-extruded
heat-sealable resin is sufficiently cooled to form the desired pattern. For
example, a
temperature range of about -15° to about -10° can be sufficient
to properly form the desired
pattern. The temperature range of the cooling roll 104 can vary according to
the composition
of the resin, the composition of the gas-impermeable base layer 108,
environmental
conditions, etc. and can require calibration. Also, the cooling roll 104 can
be sized to have a
larger diameter than the laminating roll 102, thereby bringing the melt-
extruded resin into
contact with more cooled surface area. For example, the diameter of the
cooling roll 104 can
be about one-and-a-half to about three times as large as that of the
laminating roll 102.
[0038] The heat-sealable inner layer 106 is typically made of a thermoplastic
resin.
For example, the resin can be comprised of polyethylene (PE) suitable for
preserving foods
and harmless to a human body. A vacuum bag can be manufactured by overlapping
two
panels such that the heat-sealable resin layers 106 of the two panels is
brought into contact
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and heat is applied to a portion of the periphery of the panels to form an
envelope. The
thermoplastic resin can be chosen so that the two panels strongly bond to each
other when
sufficient heat is applied.
[0039] The gas-impermeable base layer 108 is fed to the gap between the
cooling
roll 104 and the laminating roll 102 by a feeding means (not shown). The gas-
impermeable
base layer can be comprised of polyester, polyamide, ethylene vinyl alcohol
(EVOH), nylon,
or other material having similar properties and capable of being used in this
manufacturing
process, and also capable of being heated. The gas-impermeable base layer 108
can consist
of one layer, or two or more layers. When employing a multilayer-structured
base layer, it
should be understood that a total thickness thereof is also adjusted within
the allowable range
for the total gas-impermeable base layer 108.
[0040] An extruder 110 is positioned in such a way that the melt-extruded
resin is
layered on the gas-impermeable base layer 108 by feeding the melt-extruded
resin to the nip
between the cooling roll 104 and the gas-impermeable layer 108. The resin is
fed through a
nozzle 112 of the extruder 110. The temperature of the melt-extruded resin is
dependent on
the type of resin used, and can typically range from about 200° to
about 250°. The amount
of resin to be extruded into the laminating unit 100 is dependent on the
desired thickness of
the heat-sealable inner layer 106.
[0041] A pattern fabricated on the circumferential surface of the cooling roll
104 in
accordance with one embodiment of the present invention can include cavities
for forming
raised walls defining one or more discrete trays. The pattern can also
optionally include
cavities (and/or protuberances) forforming ridges or protuberances within the
raised walls for
suspending a perishable or other product over a base of the trays, thereby
allowing liquid to
collect in the tray. The resin extruded by the nozzle 112 is pressed between
the cooling roll
104 and the gas-impermeable base layer 108 and flows into the cavities of the
cooling roll
104. The melt-extruded resin quickly cools and solidifies in the desired
pattern while adhering
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to the gas-impermeable base layer 108, thereby forming the heat sealable inner
layer 106 of
the panel. The heat-sealable inner layer 106 can be formed while the resin is
sufficiently
heated to allow the resin to flow, thereby molding the resin, unlike
conventional methods
adopting a post-embossing treatment where the heat-sealable inner layer is
drawn by a die
or embossed between male and female components.
[0042] FIG. 2A is a plan view of a panel formed by the cooling roll 104 for
use in a
vacuum bag, in which the heat-sealable inner layer 106 is molded in such a way
that raised
walls 232 are formed for defining a tray 230 for restricting the movement of
perishable or
other products. Within the raised walls 232 of the tray are ridges 234 for
suspending the
perishable or other products over the base of the tray. As shown, the ridges
234 are cross-
hatched and form reservoirs 236 for liquid to collect. In other embodiments,
the ridges can
be formed in a multitude of different patterns, allowing for the formation of
reservoirs 236
having a multitude of different shapes and sizes. In still other embodiments,
the tray 230 can
include protuberances, wherein the protuberances can be discrete pyramids,
hemispheres,
etc., thereby allowing liquid to collect evenly in the base of the tray 230.
In still other
embodiments, the panel 220 can include a plurality of discrete trays 230, each
sized to suit
t
an application and optionally having ridges 234 or protuberances. One of
ordinary skill in the
art can appreciate the myriad of different ways in which the panel 220 can be
configured to
restrict the movement of perishable products within a vacuum bag.
[0043] The thickness of the raised walls 232 and ridges 234 formed on the heat-
sealable inner layer 106 of a panel 220 can be determined by the depth of the
cavities of the
cooling roll 104, and the width of the raised walls 232 and ridges 234 can be
determined by
the width of the cavities. Thus, the shape, width, and thickness of the raised
walls 232 and
ridges 234 can be controlled by changing the specifications for the cavities
of the cooling roll
104. FIG.2B is a cross-sectional view of the panel 220 described above. In the
heat-sealable
inner layer 106, the raised walls 232 can range, for example, from about 35-75
mils or more
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in height, the gas-impermeable base layer 108 can range, for example, from
about 0.5-8.0
mils in thickness, and the heat-sealable inner layer 106, can range, for
example, from about
0.5-6.0 mils in thickness (without the raised walls 232). Optionally, ridges
234 or
protuberances can by included. The ridges 234 or protuberances can have a
height lower
than the raised walls 232, thereby suspending the perishable or other product
while still
retaining the perishable product within the tray 230. For example, if the
raised wall 232 is 75
mils in height, the height of the ridges 234 or protuberances can be about 30
mils. The
dimensions of the raised walls 232, the ridges 234, the base layer 108, and
the inner layer
106 are set forth to illustrate, but are not to be construed to limit the
dimensions.
[0044] FIG. 3 illustrates a bag for use in vacuum packaging in accordance with
one
embodiment of the present invention. The vacuum bag 350 comprises a first
panel 320 and
a second panel 322 overlapping each other. At least one tray 230 is formed on
the first panel
320 in accordance with an embodiment described above. The second panel 322 (or
first
panel 320) optionally includes channels (not shown) along a portion of the
panel for
evacuating air and other gases from the bag. The channels can be formed, for
example, as
described in the cross-referenced application "LIQUID-TRAPPING SAG FOR
VACUUfr/l
PACKAGING," incorporated herein by reference. The heat-sealable resin layer
106 and the
gas-impermeable base layer 108 of the first and second panels 320,322 are
typically made
of the same material respectively, but can alternatively be made of different
materials that
exhibit heat-sealability and gas-impermeability respectively. As described
above, the heat-
sealable resin layer 106 is used as an inner layer and the gas-impermeable
base layer 108
is used as an outer layer. The lower, left, and right edges of the first and
the second panel
320,322 are bonded to each other by heating, so as to form an envelope for
receiving a
perishable or other product to be vacuum packaged. Once a perishable or other
product is
placed in the vacuum bag 350, air and/or other gases can be evacuated from the
bag 350,
for example by a vacuum sealing machine as described in U.S. Pat. No.
4,941,310, which is
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incorporated herein by reference. Once the air and/or other gases are
evacuated to the
satisfaction of the user, the inlet can be sealed by applying heat, thereby
activating the heat-
sealable inner layers 106 and bonding them together.
(0045] The foregoing description of preferred embodiments ofthe present
invention
5 has been provided for the purposes of illustration and description. It is
not intended to be
exhaustive or to limit the invention to the precise forms disclosed.
Obviously, many
modifications and variations will be apparent to the practitioner skilled in
the art. The
embodiments were chosen and described in order to best explain the principles
of the
invention and its practical application, thereby enabling others skilled in
the art to understand
10 the invention for various embodiments and with various modifications that
are suited to the
particular use contemplated. It is intended that the scope of the invention be
defined by the
following claims and their equivalence.