Note: Descriptions are shown in the official language in which they were submitted.
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RELEASABLY SEALABLE BAG COMPRISING
A COMPOSITE SHEET MATERIAL
FIELD
The present invention relates to a bag for airtight storage, particularly of
foods, and for airtight and liquid-tight sealing during cooking. More
specifically, it
relates to a bag comprised of at least one sheet of a composite film material
provided with a pressure sensitive adhesive protected from inadvertent
adherence, or a sheet having at ieast one portion comprised of such a
composite
film material, the adhesive being releasably sealable to, e.g., another
portion of
the same film sheet or to a different film sheet when pressed thereagainst, to
form an interior of the bag.
BACKGROUND
Containers for food storage are well-known and have been made available
in many forms, e.g., plastic boxes in various shapes with flexible fitted lids
such
as those sold under the brand name "TUPPERWARE" from the Tupperware
Company, USA, and plastic bags with three sealed sides and a zipper-style
reclosable opening such as those sold under the brand name "ZIPLOC" storage
bags from the S. C. Johnson Company in the United States and the Asahi Kasei
Company in Japan.
Another type of food storage bag that is very commonly used by
consumers is the complimentary polyethylene "stock bags" that are provided
free
of charge by many grocery stores and food markets. Such bags are also
commercially available under the name UBETM Kitchen Bags from the UBE Film
Company of Onoda City, Yamaguchi Prefecture, Japan. This type of bag is
usually sealed by tying the free ends of the bag directly to each other, or by
using
some type of metallic or plastic fastener. However, consumers frequently do
not
seal such bags at all before placing them in the refrigerator.
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In addition, various film materials that adhere to the surface of a plate or
other container via electrostatic cling have previously been available for
food
storage uses. These types of film materials are generally provided as a roll,
the
free edge of which is grasped by the user and unrolled to a desired length,
then
cut by a blade attached to the package in which the roll is stored; then the
cut
length of film is placed over the food to be stored and adhered by
electrostatic
cling to the surface of the plate or container in which the food is placed.
Such
films can also be directly used to wrap and store food; in such cases, the
wrap is
intended to self-adhere as opposed to adhering to a plate or other container.
1o Examples of such commercially available films are those sold under the
brand
names "SARAN WRAP" from the Asahi Kasei Company and "KRE WRAP" from
the Kureha Kagaku Company, both of Japan.
However, such conventional storage bags and films are not without
drawbacks. Airtightness of seal, and corresponding inability to maintain
freshness, is frequently problematic. Convenience of use is also an issue for
consumers. Rolis of film can be unmanageable to u,se as they often prematurely
stick, and it is often difficult to locate the free edge of the film. With
respect to
pre-formed storage bags, it can be difficult to firmly and completely seal the
zippered end of the bag; it can further be difficult to place the food to be
stored
20, inside the bag due to the relatively small size of the opening.
It is also known to re-heat various prepared foods using flexible bags or
pouches called retortable bags. For example, certain prepared foods that are
suitable to be eaten after re-heating can be purchased in hermetically sealed
plastic bags. The sealed bag is placed in boiling water, and the heat from the
boiling water re-heats the food without penetrating the bag. The user then
only
has to cut open the bag and remove the contents. A common example of this
type of product is curry, available for example, from the House Shokuhin, S&B
Shokuhin, and Ajinomoto Companies of Japan.
However, the types of food products that can packaged and re-heated in
this manner are limited. In addition, these retortable bags cannot be used to
actually cook fresh foods; they can only be used to re-heat foods that have
been
processed and preserved.
Neither are the conventional food storage bags discussed above suitable
for re-heating stored foods or for cooking fresh foods in hot water, as there
is no
practical method available to ensure air and liquid-tightness when sealed or
during re-heating or cooking. In addition, such bags may not have material
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properties that would permit them to sustain the heat of boiling water or the
heat
generated by a microwave oven without degenerating. Even if it is assumed that
such material itself is air and liquid tight, practical methods for sealing/re-
sealing
of such bags are extremely limited.
Therefore, it can be seen that there remains a desire to provide a
convenient and versatile bag-type container for airtight food storage and for
airtight/liquid-tight sealing during cooking of fresh foods as well as re-
heating of
foods. None of the existing art provides all of the advantages and benefits of
the
present invention.
SUMMARY
The present invention relates to a bag comprised of at least two
superimposed sheets of film material having at least a portion of their
superimposed edges being permanently sealed, wherein at least one of the
sheets is a composite film material provided with a pressure sensitive
adhesive
protected from inadvertent adherence, the adhesive-bearing film sheet being
releasably sealable to the other film sheet when pressed thereagainst to
create a
seal perimeter, wherein an interior of the bag. is comprised within the seal
perimeter.
Further disclosed is a bag comprised of a first sheet of film material and a
second sheet of film material, wherein at least one of the sheets is a
composite
film material provided with a pressure sensitive adhesive protected from
inadvertent adherence, the adhesive-bearing film sheet being releasably
sealable to the other film sheet when pressed thereagainst to create a seal
perimeter, wherein an interior of the bag is comprised within the seal
perimeter.
Still further disclosed is a bag comprised of a sheet having a first portion
with at least one first portion free edge, a second portion with at least one
second portion free edge, and a juncture area between the first portion and
the
second portion, wherein at least one of the first portion or the second
portion is
comprised of a composite film material provided with a pressure sensitive
adhesive protected from inadvertent adherence, and wherein the first portion
is
overiaid onto the second portion by folding about the juncture area, the first
and
second portions being releasably sealable to each other along a seal perimeter
created by pressing one of the portions against the other of the portions,
wherein
an interior of the bag is comprised within the seal perimeter.
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Also disclosed is a bag comprised of a sheet having a first portion with at
least one first portion free edge, a second portion with at least one second
portion free edge, and a juncture area between the first portion and the
second
portion, wherein at least one of the first portion or the second portion is
comprised of a composite film material provided with a pressure sensitive
adhesive protected from inadvertent adherence, at least one of the first or
second portion free edges is provided with an opening indication means that
visually contrasts with the other first or second portion free edges, and
wherein
the first portion is overlaid onto the second portion by folding about the
juncture
lo area, the first and second portions being releasably sealable to each other
along
a seal perimeter created by pressing one of the portions against the other of
the
portions, and the seal perimeter further comprising the juncture area.
The present invention additionally relates to methods for storage and
cooking using the bags of the present invention.
These and other features, aspects, and advantages of the invention will
become evident to those skilled in the art from a reading of the present
disclosure.
BRIEF DESCRIPTION OF THE DRAWINGS
While the specification concludes with claims particularly pointing out and
distinctly claiming the invention, it is believed that the present invention
will be
better understood from the following description of preferred embodiments
taken
in conjunction with the accompanying drawings in which:
Figs. la-c are perspective views of preferred embodiments of a bag of the
present invention;
Fig. 2a is a plan view of a sheet of composite film material prior to
formation into the preferred embodiment of a bag shown in Fig. 2b;
Fig. 2b is a perspective view of the bag formed from the sheet shown in
Fig. 2a;
Fig. 2c is a plan view of the bag shown in Figs. 2a and 2b with a food item
placed in an interior of the bag;
Fig. 3 is a top plan view of a preferred embodiment of the composite
material of the present invention, showing a piece of flexible film having
thermoformed truncated conical protrusions between a grid of pressure
sensitive
adhesive;
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Fig. 4 is a sectioned elevation view of the composite material of Fig. 3,
taken along section line 4-4 of Fig. 3, showing the protrusions acting as
stand-
offs from an adhesive layer between protrusions, such that a target surface
contacting the outermost ends of the protrusions does not contact the adhesive
5 layer;
Fig. 5 is a sectioned elevation view thereof, similar to Fig. 4, showing the
effect of pressing the dimpled composite material against the target surface,
such
that protrusions collapse and allow the adhesive layer between protrusions to
contact the target surface;
Fig. 6 is a plan view of another preferred embodiment of a three-
dimensional, nesting resistant composite sheet material according to the
present
invention;
Fig. 7 is a perspective view of the bag shown in Figs. 1 a and 1 c with a
food item placed in an interior of the bag;
Fig. 8 is a perspective view of the bag shown in Figs. I a and 1 c with food
items placed inside interiors of the bag in a compartmentalized fashion; and
Fig. 9 is a graphical representation of the weight deprivation test data of
Example 1 comparing a bag of the present invention to a conventional food
storage bag.
DETAILED DESCRIPTION
Citation of any reference is not an admission regarding any determination as
to
its availability as prior art to the claimed invention.
Herein, "comprising" means that other, steps and other components which
do not affect the end result can be added. This term encompasses the terms
"consisting of' and "consisting essentially of."
One preferred embodiment of the bag of the present invention is
comprised of at least two superimposed sheets of film material having at least
a
portion of their superimposed edges being permanently sealed. For example, in
the embodiment of the bag 10 that is shown in Figs. 1 a-1 c, superimposed
sheets
of film material 20 and 30 are permanently sealed along at least one of their
superimposed edges. For example, first sheet 20 has edges 22, 24, 26, 28.
Second sheet 30 has edges 32, 34, 36, and 38. In this embodiment, at least one
pair of the superimposed edges is permanently sealed, e.g., edge 22 to edge
32,
edge 24 to edge 34, edge 26 to edge 36, or edge 28 to edge 38 in the
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embodiment of Fig. 1 a; in the embodiment of Fig. 1 c, edge 23 to edge 33,
edge
27 to edge 37, or edge 29 to edge 39, may be permanently sealed. For
example, the permanent seal may be formed as indicated by the reference
numerals 12a and 12b in Figs. I a and 1 c and reference numeral 13 in Fig. 1
b.
It should be understood that the permanently sealed portion of the edges
need not extend for the entire length of the superimposed edges, as it does in
the preferred embodiment shown in Figs. la-c. The permanent seal may be
provided at any portion and for any desired length of the superimposed edges.
As used herein, "permanently sealed" means that these edges are not
1 o intended to be opened by the consumer during use of the bag 10; they are
not
releasably sealable. Any method known to those of skill in the art, e.g., heat
sealing, can be use to create the permanently sealed portion of the
superimposed edges of the bags herein.
If the bag is of a square or rectangular shape, as shown in Fig. 1 a, it may
be desirable for two of the superimposed edges to be permanently sealed, e.g.
edge 26 of first sheet 20 is permanently sealed to edge 36 of second sheet 30
along the permanent seal 12b; and edge 28 of first sheet 20 is permanently
sealed to edge 38 of second sheet 30 along the permanent seal 12a. Fig. 1 c
shows the bag of Fig. 1a in its fully opened position, the advantages of which
are
2o described in fuller detail below.
Referring again to Fig. 1a, in a preferred embodiment having two
permanently sealed edges, the two permanently sealed edges are preferably
adjacent, e.g., two of the intersecting edges of a rectangular or square
shaped
bag that are perpendicular to each other, e.g. edges 26, 36 and 28, 38.
However, two opposing, non-intersecting edges such as 22, 32 and 26, 36; or
24, 34 and 28, 38 may be selected as the permanently sealed edges.
Fig. lb shows an alternative embodiment in which the bag 10 is provided
in a triangular shape, with one pair of superimposed edges 23, 33 being
permanently sealed along permanent seal 13. Again, it should be understood
that the permanently sealed portion of the edges need not extend for the
entire
length of the superimposed edges, and may be provided at any portion and for
any desired length of the superimposed edges.
It should also be understood that the present invention is not limited to any
particular shape or configuration for the bag 10 or for the sheets 20, 30. In
addition, it is not necessary that the sheets be of identical or similar size,
or of
identical shape. Furthermore, the preferred embodiments herein are not limited
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to bags comprised of one sheet or two sheets of film material. Bags comprised
of more than two sheets are also within the scope of the present invention.
Referring again to Figs. la-c, at least one of the sheets 20, 30 is a
composite film provided with a pressure sensitive adhesive protected from
inadvertent adherence. By the phrase "inadvertent adherence" it is meant that
the adhesive bearing sheet does not prematurely stick to a target surface,
e.g.,
to the other sheet, to another portion of the same sheet, or to any other
surface,
until the user of the bag activates the adhesive by pressing the sheet. The
adhesive-bearing film sheet is releasably sealable to the other film sheet, or
to
another portion of itself, when pressed thereagainst, to create a seal
perimeter
(not shown in Figs. la-c, see Figs. 2c and 7). The composite film material
itself
will be described in greater detail below.
Thus, the seal perimeter will be created at the location chosen by the
consumer when the consumer presses the sheet. Any location can be chosen
and it should be noted that the seal perimeter need not coincide with the
edges
of the sheet material.
If the sheet 70 is of square or rectangular shape, the releasably sealable
portion of the seal perimeter may be created at or approximately at the
juxtaposed free edges (e.g., 82 and 92, 84 and 94, and 86 and 96, as shown in
2o Fig. 2b) to give the largest interior area for the bag. However, as noted
above,
the seal perimeter may be formed at any desired location.
The bag 10 may additionally be provided with an opening indication
means 21 to facilitate opening of the sheets prior to inserting an item to be
stored
or cooked. The opening indication means 21 may equally well facilitate re-
opening of the bag when it is desired to remove items from the bag after the
bag
has been sealed. Opening indication means 21 may be separate from sheets
20, 30, e.g., a tab made from material different from that of either of both
of the
sheets 20, 30. Or, opening indication means 21 may be integral with either or
both of sheets 20, 30, e.g., it may be made from a color or printing
indication in
the film that signals an appropriate opening location to the user. Preferably,
the
opening indication means visually contrasts with the other surface that it
contacts.
Another preferred embodiment of the bag of the present invention (not
shown in the Figures) is similar to that shown in Figs. la-c; however, in such
a
preferred embodiment, there are no permanently sealed edges or portions of
permanently sealed edges. In such a preferred embodiment, at least one of the
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film sheets is a composite film material as described below, and the adhesive-
bearing sheet is releasably sealable to the other film sheet when pressed
thereagainst to create a seal perimeter that forms an interior of the bag.
Yet another preferred embodiment of the bag of the present invention is
shown in Figs. 2a-b. In this embodiment, the bag 10 is comprised of a single
sheet 70 as described in detail below. The sheet 70 has a first portion 80, a
second portion 90, and a juncture area 75 located generally between the first
and
second portions 80, 90. The juncture area 75 is shown in dashed lines in Fig.
2a
to indicate that it does not have an exactly defined area or location. In
addition, it
lo can divide the first portion 80 and the second portion 90 into areas of any
respective sizes or shapes; these portions need not necessarily be of equal or
approximately equal size or shape.
It should be noted that the rectangular shaped sheet 70 that is shown in
Fig. 2a is not intended to be a limiting shape. Like the preferred embodiment
shown in Figs. 1 a-c, any shape for the sheet 70 is within the scope of the
present
invention, e.g., circular, oval, triangular, amorphous, decorative.
The first portion is bounded by at least one first portion free edge. In the
embodiment shown in Fig. 2a, the first portion free edges are indicated by the
reference numerals 82, 84, and 86. The second portion is bounded by at least
one second portion free edge. The second portion free edges are indicated by
the reference numerals 92, 94, and 96. Again, it should be noted that this
embodiment is not limited to having a specified number of free edges. For
example, if the sheet 70 were oval, there would be one continuous first
portion
free edge that would not be shown in three segments as shown in Fig. 2a.
In one preferred embodiment, at least one of the first portion 80 or the
second portion 90 is comprised of a composite material provided with a
pressure
sensitive adhesive protected from inadvertent adherence. In another preferred
embodiment, both of the first portion 80 and the second portion 90 is
comprised
of a composite material provided with a pressure sensitive adhesive protected
from inadvertent adherence. In yet another preferred embodiment, the juncture
area 75 is further comprised of a composite material provided with a pressure
sensitive adhesive protected from inadvertent adherence.
In another, more preferred embodiment, the sheet is a unitary sheet of a
composite material provided with a pressure sensitive adhesive protected from
inadvertent adherence; in other words, the first portion 80, the second
portion 90,
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and the juncture area 75 exist as locations on the same unitary sheet from
which
the bag is formed.
The bag 10 is formed from the sheet 70 as follows, see Fig. 2b. First
portion 80 is folded generally at or around the juncture area 75 so that it,--
is
overlaid onto the second portion 90. A seal perimeter 85 may be created by
pressing one of the first or second portions against the other portion at a
desired
location. Thus, an interior of the bag 10 is formed within the seal perimeter
85.
The seal perimeter may be created totally independent of the juncture area 75
if
desired by the consumer, for example as shown on Fig. 7. Or, the interior may
1o be further be comprised within the juncture area as well as within the seal
perimeter 85 as shown on Fig. 2c.
In another preferred embodiment of a bag of the type shown in Figs. 2a-c,
it is desirable to provide at least one of the first or second portion free
edges with
an opening indication means, as described hereinbefore and in a manner similar
to that shown in Fig. 1 a. Preferably, such an opening indication means
visually
contrasts with the other first or second portion free edges that are not
provided
with the opening indication means.
In each of the above-described embodiments, at least one of the sheets
or 30, or the sheet 70, in the embodiments described in connection with Figs.
20 1 a-c, or at least one of the first portion 80 or the second portion 90 in
the
embodiments described in connection with Figs. 2a-c, is comprised of a
composite material such as that described in Hamilton et al. U.S. patent no.
5,662,758, "Composite Material Releasably Sealable to A Target Surface When
Pressed Thereagainst and Method of Making," issued on September 2, 1997;
Hamilton et al. US patent no. 5,871,607, "Material Having A Substance
Protected
By Deformable Standoffs And Method of Making," issued February 16, 1999;
McGuire et al. U.S. patent 5,965,235, "Three-Dimensional, Amorphous-
Patterned, Nesting-Resistant Sheet Materials and Method and Apparatus for
Making Same," issued October 12, 1999; and Hamilton et al. US patent no.
3o 5,968,633, "Selectively-Activatible Sheet Material For Dispensing And
Dispersing
a Substance Onto A Target Surface," issued on October 19, 1999.
Such a composite material is a flexible film coated with a pressure
sensitive adhesive for releasably sealing to a target surface and for
preventing
premature sticking to a target surface. More particularly, the composite
material
is a flexible film that has protrusions formed on an adhesive side which act
to
space a pressure sensitive adhesive from a target surface until the film is
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pressed thereagainst. According to the present invention, the "target surface"
herein is the other of the film sheets 20 or 30 in the embodiments shown in
Figs.
la-c, or another portion of the same sheet 70 as shown in the Figs. 2a-c
embodiments.
Although a full disclosure of the composite materials herein is given in the
above-referenced patents, a concise description will be repeated herein. One
embodiment of the composite film is shown in Fig. 3 and is generally indicated
as
100. The composite film 100 generally includes a piece of flexible film 120
having protrusions 140 and a layer of pressure sensitive adhesive 160 located
between protrusions 140. In the embodiment of the film 100 that is shown in
Fig.
3, the protnasions 140 are conical in shape with truncated or domed outermost
ends 180. The protrusions 140 are equally spaced in an equilateral triangular
pattern, all facing the same direction. They are spaced center to center a
distance approximateiy two protrusion diameters. Protrusions 140 have heights
which are preferably less than their diameters, so that when they collapse,
they
collapse along an axis which is substantially perpendicular to a plane of film
120.
This mode of collapse avoids protrusions 140 folding over and blocking
adhesive
from contact with a target surface.
Fig. 4 shows a target surface 200, which according to the present
invention is either another film sheet that comprises the bag 10 or another
portion
of the same film sheet from which the bag is formed, being spaced away from
the
layer of pressure sensitive adhesive 160 by outermost ends 180 of protrusions
140. Fig. 5 shows the target surface 200 contacting a layer of pressure
sensitive
adhesive 160 after protrusions 140 have partially inverted on themselves under
pressure applied to the non-adhesive side of flexible film 120, as indicated
by
force F.
In the embodiment of the film 100 that is shown in Figs. 3-5, the conical
protrusions 140 have a base diameter of about 0.015 inches (0.381 mm) to about
0.03 inches (0.762 mm). They also have a center to center spacing of from
about 0.03 inches (0.762 mm) to about 0.06 inches (1.524 mm), and a protrusion
height of about 0.004 inches (0.102 mm) to about 0.012 inches (0.305 mm). The
film material may be made from homogenous resins or blends thereof. Single or
multiple layers within the film structure are contemplated whether co-
extruded,
extrusiori-coated, laminate or combined by other known means. The key
attribute of the film material is that it be formable to product protrusions
and
valleys. Useful resins include polyethylene, polypropylene, PET, PVC, PVDC,
latex structures, nylon, etc. The preferred film material is from about 0.01
to
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about 0.02 mm, more preferably from about 0.012 to about 0.015 mm, nominal
thickness polyethylene. A preferred film material is 100% HDPE film, about
0.012 mm, available from the Tredegar Co., USA. Such films are also available
from the Exxon Co., USA.
The layer of pressure sensitive adhesive 160 is preferably a hot melt
adhesive about 0.025 mm thick. Such hot melt adhesives, for example those
available from the Findley Co., USA, e.g., specification nos. ATO Findley
2630.07, 2630.08, and 2630.09, and those available from the H.B. Fuller Co. of
Minnesota, USA, e.g., specification nos. HB Fuller HL-2115X, HB Fuller HL
1o 1711-XZP, and HB Fuller HL 1717-X, are suitable for use herein.
Altematively,
other adhesives including latex can also be used for the adhesive layer 160.
The size and spacing of protrusions is optimized to provide a continuous
adhesive path for fluid tight seals, but without generating a film that is
easily
stretched. Stretched film result in residual forces parallel to the plane of
adhesive contact, which may cause the weak adhesive bond to break.
Even more preferably, the composite sheet herein is a three-dimensional
composite sheet material that resists nesting of superimposed layers into one
another as described in the aforementioned McGuire et al. US patent 5,965,235.
To provide such nesting resistant advantages, the protrusions form an
2o amorphous pattern of a plurality of different two-dimensional geometrical
shapes
on one side of the composite sheet material; on the opposite side are provided
a
plurality of spaced, three-dimensional hollow depressions corresponding to the
protrusions, such that the protrusions are hollow. The term "amorphous" as
used
herein is generally in accordance with the ordinary meaning of the term, i.e.,
a
pattern which exhibits no readily perceptible organization, regularity, or
orientation of constituent elements. in such a pattern, the orientation and
arrangement of one element with regard to a neighboring element bear no
predictable relationship to that of the next succeeding element(s) beyond.
Within the preferred amorphous pattern, protrusions will preferably be
3o non-uniform with regard to their size, shape, orientation with respect to
the web,
and spacing between adjacent protrusion centers. Fig. 6 is a plan view of a
representative three-dimensional, nesting-resistant sheet material 210 in
accordance with the present invention. The protrusions are indicated by the
reference numeral 240 and the spaces by reference numeral 220. Also indicated
on Fig. 6 is the dimension A, which represents the width of spaces 220,
measured as the substantially perpendicular distance between adjacent
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substantially parallel walls at the base of the protrusions. In a preferred
embodiment, the width of the spaces 220 is preferably substantially constant
throughout the pattern of protrusions.
Protrusions 240 are generated with non-uniform size and shape so that
one sheet or piece of the material 200 may be placed in face to face contact
with
another sheet or piece of material 200 without nesting occurring between the
two
sheets. The nesting-resistant feature is achieved because the amorphous
pattern of the protrusions as discussed above limits the ability of the face
of one
sheet to align with the back of another sheet whereby the protrusions of one
1o layer enter the depressions formed behind each protrusion in an adjacent
layer.
The benefit of narrow constant width spaces between protrusions is that
protriasions cannot also enter spaces 220 when layers of material 200 are
placed
face to face.
The use of polygons having a finite number of sides in the amorphous
pattern arranged in an interlocking relationship provides an advantage over
structures employing circular or near circular shapes. Patterns such as arrays
of
circles are limited in terms of the amount of area the circles can occupy
relative
to the non-circled area between adjacent circles. More specifically, even in a
pattern where adjacent circles touch at their point of tangency there will
still be a
given amount of space "trapped" at the "corners" between consecutive tangency.
Accordingly, even amorphous patterns of circular shapes are limited in terms
of
how little non-circle area can be designed into the structure. Conversely,
interlocking polygonal shapes with finite numbers of sides (i.e., no
curvilinear
sides) can be designed so as to pack closely together and in the limiting
sense
can be packed such that adjacent sides of adjacent polygons can be in contact
along their entire length such that there is no "trapped" free space between
corners, see Fig. 6. Preferably, the amorphous pattern herein has a
statistically
controlled degree of randomness, as described in detail in U.S. patent
5,965,235.
The three-dimensional shape of the individual protrusions is believed to
play a role in determining both the physical properties of individual
protrusions as
well as overall web properties. The use of an interlocking polygonal base
pattern
for the protrusions is believed to be highly advantageous herein. Such a
polygonal pattern is preferably comprised of interlocking convex polygons each
having a finite number of substantially linear sides with facing sides of
adjacent
polygons being substantially parallel. However, it should be understood that
the
protrusions may be formed from virtually any three dimensional shape.
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Protrusions 240 are preferably spaced center to center an average
distance of approximately two protrusion base diameters or closer, in order to
minimize the volume of valleys between protrusions and hence the amount of
adhesive located between them. Preferably, the protrusions have heights that
are less than their diameters, so that when they deform, they deform by
substantially inverting and/or crushing along an axis that is substantially
perpendicular to a plane of the material. This protrusion shape and mode of
deforming discourages protrusions from folding over in a direction parallel to
a
plane of the material so that the protrusions cannot block the adhesive in the
1o valley between them from contact with a target surface.
A preferred adhesive herein is a hot melt pressure sensitive adhesive
about 0.025 mm thick. Such hot melt adhesives, for example those available
from the Findley Co., USA, e.g., specification nos. ATO Findley 2630.07,
2630.08, and 2630.09, and those available from the H.B. Fuller Co. of
Minnesota, USA, e.g., specification nos. HB Fuller HL-2115X, HB Fuller HL
1711-XZP, and HB Fuller HL 1717-X, are suitable for use herein. Alternatively,
other adhesives including latex can also be used for the adhesive layer 160.
The film material may be made from homogenous resins or blends
thereof. Single or multiple layers within the film structure are contemplated,
whether co-extruded, extrusion-coated, laminated or combined by other known
means. The key attribute of the film material is that it be formable to
produce
protrusions and valleys. Useful resins herein include polyethylene,
polypropylene, PET, PVC, PVDC, latex structures, nylon, etc. Preferred
material
gauges are about 0.0025 mm to about 0.25 mm. A preferred film material is
100% HDPE film, about 0.012 mm, available from the Tredegar Co., USA. Such
films are also available from the Exxon Co., USA. Forming may be done by
mechanical embossing, vacuum thermoforming, hydroforming, or combinations
thereof, as well as by other forming methods known to those of skill in the
art.
It should be noted that while the entire surface of a sheet preferably
3o exhibits such an amorphous pattern, under some circumstances it may be
desirable for less than the entire surface of such a sheet to exhibit such a
pattern. For example, a portion of the sheet may exhibit some regular pattern
of
protrusions or may in fact be free of protrusions so as to present a generally
planar surface.
In addition, the designer may separate the amorphous regions with a
regular, non-amorphous pattern or a "blank" region with no protrusions at all,
or
CA 02406513 2005-12-12
14
any combination thereof. The shape and dimensions of the non-amorphous
regions can further be customized.
As noted previously, in the embodiment shown in Figs. 1 a-c, at least one of
the sheets 20 or 30 comprising the bag 10, or a portion of the sheet for
embodiments made from a single sheet, is a composite sheet material as
described above. The other sheet material or portion thereof of may be the
same
or a similar composite material; or, the other sheet or portion thereof may be
a
non-composite sheet material may be any conventional film material known to
those of skill in the art, e.g., high density polyethylene or low density
io polyethelene. In the embodiment shown in Figs. 2a-c, at least a portion of
the
sheet 70 forming the bag 10 is a composite sheet material as described above.
As a result, a user of the bag 10 can releasably seal the bag as desired by
simply
pressing at any other desired location to activate the adhesive of the
composite
sheet to tightly seal it at a seal perimeter to a target sheet or target
portion.
It may also be desirable to provide the sheet materials herein or any
portion or portions thereof some type of decorative printing for aesthetic
appeal.
Such printing may be done in any pattem, color, style, design, etc.
For example, Fig. 7 shows a food item 40 contained in the preferred
embodiment of the bag 10 in which a seal perimeter 45 has been created by
pressing forces exerted by the user generally- in the directions of the arrows
labeled "S1n and "S2" around the periphery of the food item. Such a bag 10
could be comprised of any of the embodiments described herein.
Another example of a use of the bag 10 is illustrated in Fig. 8. Namely, it
is possible to individually compartmentalize several items for storage,
whether
they are the same type of item or different items, within one bag. Separate
airtight and liquid tight seal perimeters 45a-d can be formed around
individual
items 50 by pressing the film in the desired areas. Within each seal perimeter
45a-d is an iridividual bag interior. Alternatively, the bag can simply be
pressed
as indicated by the arrows S1-S4 to create four sealed compartments for
sealing.
3o Such a bag 10 could be comprised of any of the embodiments described
herein.
Of course, it should be understood that the examples shown in Figs. 7 and
8 are not intended to be limiting, as many different ways to use the various
embodiments of the bags of the present invention are possible and are within
the
scope of the present invention.
Fig. 1 c shows the bag of Fig. 1 a in its fully opened state, illustrating one
of
the advantages of the present invention. As shown in Fig. 1 c, the bag 10 is
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provided with a large insertion and removal area that exists as a result of
the fact
that the bag has two superimposed edges that are not permanently sealed. For
example, representative dimensions for a bag according to the present
invention
are about 29.2-30.0 cm by about 30.0 cm. For a bag such dimensions, the
5 insertion/removal open area is about 1040 cm2, calculated by defining the
open
area as a complete circle.
Other non-limiting dimensions generally convenient for household use
include about 15.0 cm by about 15.0 cm, and about 60.0 cm by about 60.0 cm.
In contrast, conventional bags having only one side usable for insertion
10 and removal, e.g., zipper-type bags or stock bags, cannot provide such
advantages. In the commercially available zipper-type bags, the opening may
actually be narrower than the actual bag dimensions due to the area necessary
for incorporation of the zipper materials and closure. Such zipper-type bags
can
therefore be inconvenient or impossible to use for large or irregularly shaped
15 items. For example, a commercially avaiiable ZIPLOC vegetable storage bag,
Large Size, has dimensions of about 26.8 cm by 27.9 cm. Yet its
insertion/removal open area is only about 223 cm2, calculated by defining the
open area as a complete circle.
Therefore, it can be seen the open area mouth size of the embodiment of
the bag shown in Figs. 1 a and 1 c of the present invention, when in its fully
opened state, is at least about 50% greater than that of other commercially
available storage bags; e.g., stock bags and zipper bags.
While it will be appreciated that a square or rectangular shape gives a
large interior area available for use and may provide two non-permanently
sealed
edges for convenient insertion and removal, other shapes can be provided and
are within the scope of the present invention, for example an oval or circular
bag
comprised of at least one sheet of the composite material described here, with
a
releasably sealable open area for insertion and removal of food items.
In addition, bags having no permanently sealed edges are equally and
sometimes more convenient to use than those having permanently sealed edges.
The type of bag that is most suitable for the intended use depends on the
desired
use, the size and shape of the item to be placed in the interior of the bag,
and the
preference of the user.
Therefore, it can be seen that the insertion and removal of food items to
be stored or cooked into and out of the preferred embodiments of the bags 10
of
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the present invention can be accomplished with ease, as the bag can
accommodate many different sizes and shapes of food items.
In addition to its advantages in terms of ease of use, the bags of the
present invention also provide improved freshness benefits for stored foods.
It is
believed that this benefit is derived from the superior airtightness
properties of
the bag of the present invention. This benefit is described in greater detail
in the
Examples herein.
Finally, it should be understood that the bags of the present invention are
not limited to food uses and may be used with equal advantage for storing or
protecting any other items, especially where air tightness and/or liquid
tightness
of seal is desired. For example, the bags can be used to store cosmetics, art
supplies, sundries, and may be conveniently used to store many different types
of articles during travel.
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EXAMPLES
In order to illustrate the storage freshness benefits of the preferred
embodiments of the present invention, the bags according to the present
invention are compared to other commercially available bags as follows.
EXAMPLE 1: Weight Deprivation Test I (Spinach)
Table 1: Weight Deprivation Test I Data
Bag of Present Invention Stored Ziploc Vegetable Bag Stored
S inach Weight Spinach Wei ht
ID Day 0 Day 8 Deprivation ID Day 0 Day 8 Deprivation (%)
(%)
(a) (b) (=(1-b/a)x100) (a) (b) (=(1-b/a)x100)
1 29.61 28.24 4.63 21 29.34 26.11 11.01
2 39.40 38.74 1.68 22 56.78 50.73 10.66
3 49.80 49.11 1.39 23 49.50 43.92 11.27
4 49.73 49.09 1.29 24 39.10 34.60 11.51
5 47.35 46.96 0.82 25 37.50 33.39 10.96
6 81.16 80.00 1.43 26 49.84 44.25 11.22
7 67.57 66.45 1.66 27 49.14 43.93 10.60
8 28.19 27.61 2.06 28 88.11 79.36 9.93
9 43.93 43.35 1.32 29 33.82 30.28 10.47
35.74 35.09 1.82 30 30.40 26.48 12.89
11 44.59 43.87 1.61 31 31.34 27.79 11.33
12 34.74 34.12 1.78 32 48.38 44.12 8.81
SUM 551.81 542.63 NA SUM 543.25 484.96 NA
Avg. 45.98 45.22 1.79 Avg. 45.27 40.41 10.89
These data are graphically represented in Fig. 9, with the diamond
1o shaped data points representing the weight loss for the bags of the present
invention, and the square shaped data points representing the weight loss for
the
commercially available ZIPLOC bags. The shaded bars represent the weight
loss data for the bags of the present invention, and the un-shaded bars
represent the weight loss data for the commercially available ZIPLOC bags.
Table 2: Weight Deprivation Test I Results
Bag of the Present ZIPLOC Vegetable Bag
Invention n=12 n=12
Weight Loss (Ave. % 1.79% 10.89%
loss on 8 day storage)
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20 Base Consumer Vote 20 0
for Freshness
The weight deprivation test is carried out as follows. An equivalent
average weight amount of a vegetable, for example spinach, is divided into two
groups according to root. One group is individually placed, i.e., one per bag,
into
(1) a bag according to the present invention; and the other group is
individually
placed into (2) a ZIPLOC brand vegetable storage bag, large size, available
from
S.C. Johnson Co./Asahi Kasei Co.
Bag (1) of the present invention is 29.2 cm in width, 30.0 cm in length, and
12.5 um in thickness (excluding the adhesive layer and the protrusions). The
material is HDPE.
ZIPLOC Bag (2) is 26.8 cm in width, 27.9 cm in length, and 40.0 um in
thickness. The material is LDPE.
In bag (1) of the present invention, air is pushed out to limit the amount of
air packed inside the bag, and the bag is sealed in the shape of the spinach
by
pressing the sheet as described hereinbefore. In ZIPLOC bag (2), air is pushed
out to limit the amount of air packed inside the bag, and the bag is sealed in
the
shape of the spinach by closing the zipper.
All bags are stored in the vegetable drawer of a household model
refrigerator. All bags are placed in one refrigerator at the same start time
on Day
0. Bags are not stacked up on each other. The temperature and humidity of the
2o refrigerator are measured as a reference at the start date, Day 0, although
actual
conditions will vary throughout the period of the test. In addition, actual
conditions vary from refrigerator to refrigerator; in general it can be
expected that
normal household refrigeration conditions are about 4-5 C and from 25-55%
relative humidity. Weight is calculated as 100% at start time, Day 0, at 4 C
and
26% relative humidity.
The bags are mixed once per day during the refrigeration cycle to mimic
household refrigerator usage. The bags are left in the refrigerator for 8
days.
At the end of the test, each piece of spinach is removed from its bag and
weighed. In addition, each group is presented to a group of 20 consumers,
preferably aged at least about 20 years. The consumers are asked which group
is fresher, and are permitted to look and to touch the spinach before making a
decision.
The result of this test is given in Table 2 above. Without being limited by
theory, it is believed that freshness is linked to water loss, i.e., as
vegetables
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lose water (which can be quantitatively measured as weight loss) they become
less fresh. Thus, it can be seen from Table 2 that less water was lost by the
spinach stored in the bag according to the present invention. The freshness
result is confirmed by consumers who compared the two groups of spinach.
EXAMPLE 2: Weight Deprivation Test II (Spinach)
Table 3: Weight Deprivation Test II Result
Bag of the Present ZIPLOC Vegetable Bag
Day Invention Deprivation (%)
Deprivation (%)
0 100.0 100.00
13 95.2 58.0
A Deprivation (%) 4.8 42.0
The weight deprivation test is carried out a second time as described
1o above, starting with a different batch of spinach on a different start day
(i.e., a
different Day 0).
Due to the fact that an different batch of spinach is used at the outset, the
percent deprivation shown in Table 3 is different from that shown in Table 2.
This is to be expected because the condition of spinach or of any other
vegetable at the time of purchase on a particular day can never truly be
duplicated at the time of purchase on a different day. In other words, each
time
that a consumer purchases a vegetable, the condition of that particular
vegetable
at the time of that particular purchase is highly variable.
A comparison of the results given in Tables 2 and 3 shows better storage
freshness during storage over conventional ZIPLOC Vegetable Storage Bags
can be expected when bags of the present invention are used to store the
vegetable. The initial condition of the vegetable is irrelevant to this
result.
EXAMPLE 3: Weight Content Deprivation Test III (Broccoli)
Table 4: Weight Deprivation Test II Result
Bag of the Present ZIPLOC Vegetable Bag
Day Invention Deprivation (%)
Deprivation (%)
0 100.0 100.0
13 98.48 82.30
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~ Deprivation (%) 1.52 17.7
The test is carried out as described above, using equivalent amounts of
broccoli. Weight is calculated as 100% at start time, Day 0, at 4 C and 38%
relative humidity.
As above, this result indicates that superior storage benefit can be
5 obtained by using the bags of the present invention.
As illustrated by the Examples above, the preferred embodiments
disclosed herein provide the advantages of superior airtightness and greater
duration of fresh condition as compared to conventional vegetable storage
bags.
Improved ease of use, convenience, and versatility for storage and
10 cooking uses are also provided, as described herein. The preferred
embodiments herein are also cost effective, easy to manufacture, and offer
versatility in usage.
METHODS OF USE
15 The present invention also relates to methods of using the bags described
herein.
Storage
A method of storing an item herein comprises placing the item in any
embodiment of a bag according to the present invention, releasably sealing the
2o bag by pressing the surface of the composite film in the desired locations
to
activate the adhesive and create the seal perimeter, and placing the sealed
bag
in a storage location. More specifically, a method for storing food herein
comprises placing cooked or uncooked food in any embodiment of a bag
according to the present invention, sealing the releasably sealable edges of
the
bag at a desired location to create the seal perimeter, placing the sealed bag
in a
storage location such as a refrigerator, and removing the food from bag after
a
period of time, preferably not exceeding about two weeks for best freshness
benefits.
Cooking By Boiling
A preferred method for cooking food herein comprises the use of boiling
water. This method comprises placing uncooked food, along with desired
seasonings or spices, into in any embodiment of a bag according to the present
invention, releasably sealing the bag by pressing the surface of the composite
film in the desired locations to activate the adhesive and create the seal
perimeter, placing the sealed bag in a quantity of boiling water sufficient
such
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that the bag is partially submerged in the hot water but remains buoyant
(preferably not touching the bottom of the pan in which the water is to be
heated)
for a time sufficient to cook the food that is placed therein, removing the
bag from
the water after that time has elapsed, and opening the bag to remove the
contents. Preferably the pan in which the hot water is contained is covered
during cooking so that the contents in the bag are cooked both from the heat
of
the water itself and also from the steam that collects inside the covered pan.
Cooking by Microwave
Another method of cooking herein comprises placing uncooked food into
1 o in any embodiment of a bag according to the present invention, releasably
sealing the bag such that the food is located in the interior of the bag,
placing the
sealed bag in a microwave oven for a time sufficient to cook the food that has
been placed therein, and removing the bag from the microwave oven after that
time has elapsed. The bag may then be opened to remove and serve the
contents. It is believed that this method is especially useful for steam
cooking of
raw vegetables such as asparagus, pumpkin, or broccoli. According to such a
method, the fresh color and appearance of the vegetable are believed to be
well-
maintained and superior to conventional methods of cooking by boiling in
direct
contact with water.
In the methods of cooking by microwave, care should be taken not to
introduce oils or oily seasonings into the bag. If such oils are introduced,
it is
believed that the temperature within the bag may exceed 125 C, thereby
comprising the structural integrity of the film material, which may cause the
bag
to melt.
Preparation of Marinated or Pickled Foods
Yet another method of food preparation herein comprises preparation of
marinated or pickled food items. This method comprises placing at least one
uncooked food item, e.g., raw vegetables, fish, or meat, and any desired
flavorant, e.g., oil, salt, herbs, soy sauce, vinegar, miso, koji (a type of
malt), or
sakekasu (a rice-based sediment derived from the sake brewing process), into
in
any embodiment of a bag according to the present invention, releasably sealing
the bag at the desired seal perimeter location, placing the sealed bag in the
refrigerator and leaving the bag in the refrigerator for a time sufficient to
flavor
the food. In most cases 1-2 nights is believed to be sufficient. The bag may
then be opened to remove and serve the contents.
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In the case of uncooked vegetables, the flavored vegetables may be
eaten as is after removal from the bag. Such vegetables may be referred to by
their Japanese name, "tsukemono." In the case of marinated fish or meat, the
marinated fish or meat must be subsequently be cooked, e.g., by grilling or
boiling as described above.
Reheating
In addition to the methods of preparation for uncooked foods above, any
embodiment of a bag 'according to the present invention may be used to reheat
foods that have already been cooked. The boiling methods described above are
1o preferred for reheating, as foods containing oils may cause the bag to
become
too hot if placed in a microwave oven.
In the reheating methods herein, water temperatures of less than 100 C
(boiling) may be used, as the higher level of heat generated by boiling water
may
not be needed in cases where the food is not raw or uncooked and there is no
danger of eating undercooked foods. Depending on the type of food item to be
reheated and the user's preference as to how warm this food item should be,
temperatures of from about 50 C to about 100 C are suitable. As a non-limiting
example, it may be desired to warm a dessert cake that has been stored in the
refrigerator prior to eating.
However, it bears repeating that for raw or uncooked foods, boiling at
100 C is preferred to avoid any problems or sickness that could arise as a
result
of eating undercooked foods.
It is understood that the examples and embodiments described herein are
for illustrative purposes only and that various modifications or changes in
light
thereof will be suggested to one of skill in the art without departing from
the
scope of the present invention.
