Flexible storage bag with selectively-activatible closure

The present invention provides a flexible storage bag comprising at least one sheet of flexible sheet material assembled to form a semi-enclosed container. The bag has an opening and a closure means for sealing the opening to convert the semi-enclosed container to a closed container. The closure means comprises a strip of material forming at least a portion of the periphery of the opening having a first side facing inwardly toward the opening and a second side facing outwardly of the opening. The first side exhibits an adhesion peel force after activation by a user which is greater than an adhesion peel force exhibited prior to activation by a user. In a preferred embodiment, the flexible storage bag includes at least one auxiliary venting opening located remotely from the primary opening and having an auxiliary closure means for sealing the auxiliary opening. The auxiliary opening has a periphery, and the auxiliary closure means comprises a piece of material forming at least a portion of the periphery and having a first side facing inwardly toward the opening and a second side facing outwardly of the opening. The first side exhibits an adhesion peel force after activation by a user which is greater than an adhesion peel force exhibited prior to activation by a user. In another preferred embodiment, the flexible storage bag is self-supporting with the opening extending upwardly away from a horizontal supporting surface. The flexible storage bag may further include at least one pair of opposed gussets formed in the sheet material extending in a direction normal to the opening and a substantially planar bottom extending in a direction substantially parallel to the opening, such that when the bottom is placed on a horizontal surface the flexible storage bag is self-supporting and maintains the opening in an upwardly-extending condition. Preferably, the bag maintains the opening in a substantially open condition.

FIELD OF THE INVENTION 
The present invention relates to flexible storage bags, particularly those 
suitable for use in the containment and protection of various items 
including perishable materials. The present invention further relates to 
such flexible storage bags having improved sealability for containment and 
protection of items contained within under a wide range of in-use 
conditions. 
BACKGROUND OF THE INVENTION 
Flexible storage bags for use in the containment and protection of various 
items, as well as the preservation of perishable materials such as food 
items, are well known in the art. Such bags typically comprise a 
rectangular sheet of polymeric film folded upon itself and sealed along 
two edges to form a semi-enclosed container having two flexible opposed 
sidewalls, three sealed or folded edges, and one open edge. A closure 
integrally formed with the bag such as an interlocking rib-type seal or 
separately provided such as a plastic or paper-clad-wire tie completes the 
containment assembly. 
As utilized herein, the term "flexible" is utilized to refer to materials 
which are capable of being flexed or bent, especially repeatedly, such 
that they are pliant and yieldable in response to externally applied 
forces. Accordingly, "flexible" is substantially opposite in meaning to 
the terms inflexible, rigid, or unyielding. Materials and structures which 
are flexible, therefore, may be altered in shape and structure to 
accommodate external forces and to conform to the shape of objects brought 
into contact with them without losing their integrity. Flexible storage 
bags of the foregoing variety are typically formed from polymeric film, 
such as polyethylene or other members of the polyolefin family, in 
thicknesses of between about 0.0002 inches to about 0.002 inches. Such 
films are frequently transparent but sometimes are opaque and/or colored. 
Flexible storage bags of the currently commercially available variety 
provide a means of conveniently storing a wide range of objects and 
materials in a generally disposable containment device. While flexible 
storage bags of the foregoing variety have enjoyed a fair degree of 
commercial success, their reliance upon mechanical closures tends to cause 
difficulty in operation for individuals having impaired manual dexterity 
such as children, the elderly, arthritis patients, etc. Moreover, such 
mechanical closures typically require alignment of mechanical elements for 
operation which can prove challenging for those with impaired vision or 
impaired hand-eye coordination. Many mechanical closure mechanisms also 
provide leakage sites at such locations as the end of interlocking 
channels where liquid or gases can leak into or out of the bag. 
In an attempt to address this issue alternative closure mechanisms have 
been developed which rely upon strips or regions of adhesive to bond 
superimposed regions of the bag. While these closures address some of the 
difficulties in utilizing separate closure elements or interlocking 
mechanical elements, some adhesive closure mechanisms require removable 
liners to protect the adhesive from premature activation, thus adding 
additional elements for assembly and an additional activation step before 
use. Moreover, some protected adhesive configurations require interlocking 
grooves, channels, or protrusions which must be properly registered to 
engage the adhesive, thus again raising the visual and coordination 
requirements of conventional mechanical closure mechanisms. 
While such flexible storage bags are generally highly efficient for storage 
before use, for many storage situations it is desirable to minimize the 
amount of air and/or free space above or around the contents which is 
trapped within the bag after closure to minimize storage space of filled 
bags and to aid the effectiveness of the bag in preservation of perishable 
items. Notwithstanding the type of closure mechanism employed, it is often 
difficult with conventional flexible storage bags to only partially close 
the bag and expel trapped air before completing the closure as this again 
requires a certain amount of manual dexterity and visual aptitude. 
Conventional flexible storage bags also create an inherent challenge in 
terms of being able to hold the flexible or flaccid bag in an open 
condition with at most one hand so that the other hand can manipulate 
another container to pour the contents into the bag or peel, cut, or trim 
items for insertion into the bag. It is also difficult to maintain the 
proper (usually upright) orientation of the opening of the bag during such 
filling operations. While rigid containers and flaccid containers with 
reinforced opening perimeters have been developed for such uses, their 
comparatively higher cost and limited economical disposability leave room 
for improvement. Notwithstanding the issue of maintaining the container or 
bag opening in an open condition, there also remains a need for a flexible 
yet self-standing container with the foregoing attributes to facilitate 
easy hands-free filling. Flexible storage bags on the other hand which are 
constructed of more inexpensive materials to promote disposability 
typically lack the structure necessary for stable stacking of bags after 
filling. 
With regard to rigid or semi-rigid containers, it is well recognized that 
such containers have also realized a fair degree of commercial success in 
providing a means for storing a wide variety of contents. Such containers 
typically have an opening which maintains an open condition for filling 
and are typically self-supporting with the opening in the proper 
orientation for filling. Such containers also are frequently provided with 
flat bottoms and tops to provide stackability. However, such containers 
are typically constructed of more expensive materials such that 
disposability is limited. At the same time, the useful life of such 
containers is limited by damage, soiling, or other degradation naturally 
occurring in use, including degradation of the typical mechanical closure 
mechanisms. Storage of such three-dimensional, rigid or semi-rigid 
containers when empty is also a concern, since, they occupy as much volume 
empty as they do in a filled condition. Due to their comparatively 
fixed-volume construction, it is also difficult to minimize the amount of 
air or free space above or around the contents to minimize storage space 
of filled containers and to aid the effectiveness of the container in 
preservation of perishable items. Another concern is the task of matching 
usually-separate lids or closures with their respective containers for 
use. 
Accordingly, it would be desirable to provide a flexible storage bag 
combining the desirable qualities of both flexible bags and storage 
containers and minimizing the less desirable qualities of both approaches. 
More particularly, it would be desirable to provide a flexible storage, bag 
having improved sealability in use. 
It would also be desirable to provide a flexible storage bag which 
facilitates venting of trapped air before completion of closure. 
It would further be desirable to provide such a bag which is capable of 
being self-supporting in an open condition for filling purposes, yet 
stores easily by folding into a compact form. 
It would still further be desirable to provide a bag constructed from 
inexpensive materials to facilitate disposability which still promotes 
stable stacking of bags in a filled condition. 
It would be yet further desirable to provide such a bag which provides the 
foregoing attributes in a convenient unitary form, obviating the need for 
separate closure devices. 
SUMMARY OF THE INVENTION 
The present invention provides a flexible storage bag comprising at least 
one sheet of flexible sheet material assembled to form a semi-enclosed 
container. The bag has an opening and a closure means for sealing the 
opening to convert the semi-enclosed container to a closed container. The 
closure means comprises a strip of material forming at least a portion of 
the periphery of the opening having a first side facing inwardly toward 
the opening and a second side facing outwardly of the opening. The first 
side exhibits an adhesion peel force after activation by a user which is 
greater than an adhesion peel force exhibited prior to activation by a 
user. 
In a preferred embodiment, the flexible storage bag includes at least one 
auxiliary venting opening located remotely from the primary opening and 
having an auxiliary closure means for sealing the auxiliary opening. The 
auxiliary opening has a periphery, and the auxiliary closure means 
comprises a piece of material forming at least a portion of the periphery 
and having a first side facing inwardly toward the opening and a second 
side facing outwardly of the opening. The first side exhibits an adhesion 
peel force after activation by a user which is greater than an adhesion 
peel force exhibited prior to activation by a user. 
In another preferred embodiment, the flexible storage bag is 
self-supporting with the opening extending upwardly away from a horizontal 
supporting surface. The flexible storage bag may further include at least 
one pair of opposed gussets formed in the sheet material extending in a 
direction normal to the opening and a substantially planar bottom 
extending in a direction substantially parallel to the opening, such that 
when the bottom is placed on a horizontal surface the flexible storage bag 
is self-supporting and maintains the opening in an upwardly-extending 
condition. Preferably, the bag maintains the opening in a substantially 
open condition. 
Accordingly, the flexible storage bags of the present invention combine the 
desirable qualities of both flexible bags and storage containers and 
minimize the less desirable qualities of both approaches by providing 
improved sealability, facilitating venting of trapped air before closure, 
being self-supporting in an open condition for filling, storing easily by 
folding into a compact form, and being unitarily constructed from 
inexpensive materials to promote disposability and obviate the need for 
separate closure devices.

DETAILED DESCRIPTION OF THE INVENTION 
FIG. 1 depicts a presently preferred embodiment of a flexible storage bag 
10 according to the present invention. In the embodiment depicted in FIG. 
1, the flexible storage bag 10 includes a bag body 20 formed from a piece 
of flexible sheet material folded upon itself along fold line 22 and 
bonded to itself along side seams 24 and 26 to form a semi-enclosed 
container having an opening along edge 28. Flexible storage bag 10 also 
includes closure means 30 located adjacent to edge 28 for sealing edge 28 
to form a fully-enclosed container or vessel as shown in FIG. 1. Closure 
means 30 is selectively openable, sealable, and resealable, as will be 
described hereinafter. Bags such as the flexible storage bag 10 of FIG. 1 
can be also constructed from a continuous tube of sheet material, thereby 
eliminating side seams 24 and 26 and substituting a bottom seam for fold 
line 22. 
In the preferred configuration depicted in FIG. 1, the closure means 30 
completely encircles the periphery of the opening formed by edge 28. 
However, under some circumstances a closure means formed by a lesser 
degree of encirclement (such as, for example, a closure means disposed 
along only one side of edge 28) may provide adequate closure integrity. 
Flexible storage bag 10 is suitable for containing and protecting a wide 
variety of materials and/or objects contained within the bag body. FIG. 2 
depicts the storage bag 10 in an open condition wherein the closure means 
30 has been released such that edge 28 may be opened to admit materials 
and/or objects into the interior of the bag body portion of the storage 
bag 10. In FIG. 2 a plurality of generic solid objects 99 are shown within 
the storage bag 10. 
FIGS. 3 and 4 are plan views of the flexible storage bag 10 in an empty, 
closed condition so as to depict with greater clarity the geometrical 
details of another feature according to the present invention which may be 
employed in conjunction with the closure means 30 associated with the 
present invention or with other conventional closure mechanisms. FIG. 3 in 
particular depicts a flexible storage bag 10 of the type shown in FIG. 1, 
which is shown to include a secondary venting opening 50 which is located 
remotely from and non-contiguously with the primary opening which lies 
along edge 28. Secondary venting opening 50 comprises a selectively 
openable, sealable, and resealable aperture in the material of the bag 
body portion 20 of flexible storage bag 10 in accordance with the present 
invention. 
As shown in FIG. 3, the secondary venting opening 50 has its own secondary 
closure means 40 located remotely from primary closure means 30. This 
configuration provides the ability to select different materials and/or 
structures for the primary and secondary closure means. 
In contrast, FIG. 4 is a view similar to FIG. 3 of a flexible storage bag 
10 having a secondary venting opening 50 located within the region of the 
bag body 20 which comprises the primary closure means 30 but is still 
remotely located from and non-contiguously with the primary opening. The 
secondary closure means is still separately operable from the primary 
closure means 30. While this reduces the number of treatments or elements 
necessary to complete the bag, it also limits the type of closure means 
which may be utilized for the primary and secondary closure means. In such 
a configuration the closure means 30 must be compatible with the type of 
closure means required for operation of the secondary closure means 40. 
Various compositions suitable for constructing the flexible storage bags of 
the present invention include substantially impermeable materials such as 
polyvinyl chloride (PVC), polyvinylidene chloride (PVDC), polyethylene 
(PE), polypropylene (PP), aluminum foil, coated (waxed, etc.) and uncoated 
paper, coated nonwovens etc., and substantially permeable materials such 
as scrims, meshes, wovens, nonwovens, or perforated or porous films, 
whether predominantly two-dimensional in nature or formed into 
three-dimensional structures. Such materials may comprise a single 
composition or layer or may be a composite structure of multiple 
materials, including a substrate material utilized as a carrier for a 
substance. Materials found suitable for use in accordance with the present 
invention include a low density polyethylene film, 0.004 or 0.006 inch 
thickness, commercially available from Huntsman Film Products Corp. under 
the manufacturer's designation X420, and a low density polyethylene film, 
0.0015 inch thickness, commercially available from Tredegar Film Products 
under the manufacturer's designation X10266. 
Once the desired sheet materials are manufactured in any desirable and 
suitable manner, comprising all or part of the materials to be utilized 
for the bag body, the bag may be constructed in any known and suitable 
fashion such as those known in the art for making such bags in 
commercially available form. Heat or adhesive sealing technologies may be 
utilized to join various components or elements of the bag to themselves 
or to each other. In addition, the bag bodies may be thermoformed, blown, 
or otherwise molded rather than reliance upon folding and bonding 
techniques to construct the bag bodies from a web or sheet of material. 
Two recent U.S. Patents which are illustrative of the state of the art 
with regard to flexible storage bags similar in overall structure to those 
depicted in FIGS. 1 and 2 but of the types currently available are U.S. 
Pat. No. 5,554,093, issued Sep. 10, 1996 to Porchia et al., and U.S. Pat. 
No. 5,575,747, issued Nov. 19, 1996 to Dais et al. 
In accordance with the present invention, the closure means depicted in 
FIGS. 1-4 is constructed from a selectively activatible adhesive structure 
which provides a secure closure seal upon activation. Accordingly, the 
closure means comprises a selectively activatible adhesive-like material 
which bonds opposing material surfaces to one another across the opening 
formed by open edge 28 in FIG. 1. The bond between the closure means and a 
target surface is also sufficient to provide a barrier seal against 
transmission of oxygen, moisture/moisture vapor, odor, etc. such that 
perishable items may be satisfactorily enclosed and preserved to the 
extent of the barrier properties of the material itself. The target 
surface may comprise a separate element of the bag or may comprise another 
region of the closure means itself. 
As utilized herein, the term "selectively activatible" is used to refer to 
materials which exhibit substantially non-adherent properties when brought 
into contact with target surfaces until some action is taken by a user to 
"activate" the material to reveal adhesive properties. Accordingly, 
selectively-activatible properties differ from permanently-active strips 
of adhesive which rely upon removal of liner materials (typically 
silicone-coated paper strips) to expose the adhesive for use. 
Selective activation of such materials allows the user to properly position 
opposing surfaces before activation and adhesion are accomplished, as well 
as minimizing the likelihood of contamination of the closure means by bag 
contents during filling operations. This characteristic permits the 
flexible storage bag to be opened, filled, and/or manipulated in any 
desired mode without encountering the difficulties of premature clinging 
or adhering of the closure means to itself or to other portions of the 
opening or bag body, and without the need for separate release sheets, 
liners, spacers, or the like. Preferably, the selective activation process 
is reversible such that the closure means may be de-activated and the bag 
opened for filling or removal of contents and then re-activated for 
further closure without significant loss of adhesive capability. 
Although material utilized for the closure means may be provided with two 
active sides or surfaces, if desired for particular applications, in 
accordance with the present invention it is presently preferred to provide 
such material with only one active side and one inactive or inert side. 
While under some circumstances it may be acceptable or desirable to design 
the closure material so as to form a discontinuous bond pattern with 
itself or another target surface, such as by having an intermittent or 
discontinuous layer of adhesive on its active surface, it is presently 
preferred that the closure material be designed so as to exhibit the 
ability to form a continuous seal or bond with itself and with any 
sufficiently continuous target surface. 
Various means of activation are envisioned as being within the scope of the 
present invention, such as: mechanical activation by compression, 
mechanical activation by tensile forces, and thermal activation. However, 
it is envisioned that there may be or be developed other means of 
activation which would trigger an adhesive or adhesive-like character 
which would be capable of functioning as herein described. In a preferred 
embodiment the active side is activatible by an externally applied force 
exerted upon the sheet of material. The force may be an externally applied 
compressive force exerted in a direction substantially normal to the sheet 
of material, an externally applied tensile force exerted in a direction 
substantially parallel to the sheet of material, or a combination thereof 
Regardless of the manner of activation, materials useful as a closure means 
in accordance with the present invention will exhibit an adhesive, 
adherent, or tacking character as opposed to merely a clinging or affinity 
character. As utilized herein, therefore, the term "adhesive" is utilized 
to refer the ability of a material to exhibit an adherent character 
whether or not it actually includes a composition commonly understood and 
labelled as an adhesive. Accordingly, such materials will form at bond or 
seal when in contact with itself or another target surface as opposed to 
merely being attracted to such surface. While a number of approaches such 
as the use of selectively adherent materials may be utilized to provide 
the desired adhesive properties, a presently preferred approach is to 
utilize a pressure-sensitive adhesive. 
When designing materials useful as a closure means in accordance with the 
present invention, it may be desirable to tailor the particular choice of 
adhesive agent so as to provide either a permanent bond or a releasable 
bond as desired for a particular application. Where a permanent bond is 
desired, opening of the flexible storage bag for access to the item(s) 
therein requires destruction of the bag. Releasable bonds, on the other 
hand, provide access by permitting separation of the closure means from 
itself or other portions of the bag at the bond site without destruction. 
Moreover, depending upon the activation mechanism employed in the design 
of the material, the releasable bond may additionally be refastenable if 
sufficient adhesive character remains after the initial 
activation/bonding/release cycle. 
The closure materials useful in the present invention exhibit an adhesion 
sufficient to survive the likely degree of handling and external or 
internal forces the flexible storage bag is likely to encounter in use 
while maintaining the desired level of sealing engagement with the 
opposing surface such that preservation of perishable items is ensured. In 
general, minimum adhesion which maintains a seal is desired for a closure 
means, so that the closure means easily peeled open for access to the 
stored item(s). At the same time, in a preferred embodiment the closure 
means is a substantially clingless material. Suitable methods of measuring 
and quantifying adhesive and cling properties are described in greater 
detail in commonly-assigned, co-pending U.S. patent application Ser. No. 
08/744,850, filed Nov. 8, 1996 in the names of Hamilton and McGuire, 
entitled "Material Having A Substance Protected by Deformable Standoffs 
and Method of Making", the disclosure of which is hereby incorporated 
herein by reference. 
The closure means utilized in accordance with the present invention 
comprises a sheet of material having a first side and a second side. The 
first side comprises an active side exhibiting an adhesion peel force 
after activation by a user which is greater than an adhesion peel force 
exhibited prior to activation by a user. The active side of the closure 
means preferably exhibits an adhesion peel force of at least about 1 ounce 
per linear inch, more preferably between about 1 and about 2.5 ounces per 
linear inch, after activation by a user. 
One such material of current interest for use as a closure material in 
accordance with the present invention comprises a three-dimensional, 
conformable web comprising an active substance such as adhesive on at 
least one surface protected from external contact by the three-dimensional 
surface topography of the base material. Such materials comprise a 
polymeric or other sheet material which is embossed/debossed to form a 
pattern of raised "dimples" on at least one surface which serve as 
stand-offs to prevent an adhesive therebetween from contacting external 
surfaces until the stand-offs are deformed to render the structure more 
two-dimensional. Representative adhesive carrier structures include those 
disclosed in commonly assigned, co-pending U.S. patent application Ser. 
Nos. 08/584,638, filed Jan. 10, 1996 in the names of Hamilton and McGuire, 
entitled "Composite Material Releasably Sealable to a Target Surface When 
Pressed Thereagainst and Method of Making", Ser. No. 08/744,850, filed 
Nov. 8, 1996 in the names of Hamilton and McGuire entitled "Material 
Having A Substance Protected by Deformable Standoffs and Method of 
Making", Ser. No. 08/745,339, filed Nov. 8, 1996 in the names of McGuire, 
Tweddell, and Hamilton, entitled "Three-Dimensional, Nesting-Resistant 
Sheet Materials and Method and Apparatus for Making Same", Ser. No. 
08/745,340, filed Nov. 8, 1996 in the names of Hamilton and McGuire, 
entitled "Improved Storage Wrap Materials". The disclosures of each of 
these applications are hereby incorporated herein by reference. 
The three-dimensional structure comprises a piece of deformable material 
which has a first side formed to have a plurality of hollow protrusions 
separated by valleys. The plurality of hollow protrusions have outermost 
ends. The piece of material has a second side. The second side has a 
plurality of depressions therein corresponding to the plurality of hollow 
protrusions on the first side. The substance adheres to and partially 
fills the valleys between the plurality of hollow protrusions. The 
substance has a surface below the outermost ends of the plurality of 
hollow protrusions, so that when a portion of the first side of the piece 
of deformable film is placed against a target surface, the plurality of 
hollow protrusions prevent contact between the substance and the target 
surface until the portion is deformed at the target surface. Preferably, 
the plurality of protrusions deform by modes which are selected from the 
group consisting of inverting, crushing, and elongating. Preferably, in 
the inverting and/or crushing modes, each of the plurality of protrusions 
will not substantially deform until exposed to a pressure of at least 0.1 
pounds per square inch (0.69 kPa). 
FIGS. 5-9 illustrate a preferred embodiment of a material useful as a 
closure means for flexible storage bags according to the present 
invention, which comprises a three-dimensional sheet-like structure 
generally indicated as 30. Material 30 includes a deformed material 12 
having hollow protrusions 14 and a layer of substance 16 located between 
protrusions 14. Protrusions 14 are preferably conical in shape with 
truncated or domed outermost ends 18. Protrusions 14 are preferably 
equally spaced in an equilateral triangular pattern, all extending from 
the same side of the material. Protrusions 14 are preferably spaced center 
to center a distance of approximately two protrusion base diameters or 
closer, in order to minimize the volume of valleys between protrusions and 
hence the amount of substance located between them. Preferably, the 
protrusions 14 have heights which are less than their diameters, so that 
when they deform, they deform by substantially inverting and/or crushing 
along an axis which is substantially perpendicular to a plane of the 
material. This protrusion shape and mode of deforming discourages 
protrusions 14 from holding over in a direction parallel to a plane of the 
material so that the protrusions cannot block substance between them from 
contact with a target surface. 
FIG. 7 shows a target surface 90, which is smooth but which may have any 
surface topography, being spaced away from layer of substance 16 by 
outermost ends 18 of protrusions 14. Target surfaces in accordance with 
the present invention will typically comprise an opposing portion of the 
closure periphery which may or may not itself comprise a 
selectively-activatible adhesive-carrying closure means of similar type. 
FIG. 8 shows target surface 90 contacting layer of substance 16 after 
protrusions 14 have been partially deformed under pressure applied to the 
non-substance side of material 12, as indicated by force F. 
The more protrusions per unit area, the thinner the piece of material and 
protrusion walls can be in order to resist a given deformation force. 
Preferred layer of substance 16 is preferably a latex pressure sensitive 
adhesive or a hot melt adhesive, such as that available under 
specification no. Fuller HL-2115X, made by H. B. Fuller Co. of Vadnais 
Heights, Minn. Any adhesive can be used which suits the needs of the 
material application. Adhesives may be refastenable, releasable, 
permanent, or otherwise. The size and spacing of protrusions is preferably 
selected to provide a continuous adhesive path surrounding protrusions so 
that air-tight seals may be made with a target surface and a desired level 
of adhesion with a target surface, while also providing the optimum 
pattern of standoffs for selective activation. 
Film materials may be made from homogeneous 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 include polyethylene, 
polypropylene, PET, PVC, PVDC, latex structures, nylon, etc. Polyolefins 
are generally preferred due to their lower cost and ease of forming. Other 
suitable materials include aluminum foil, coated (waxed, etc.) and 
uncoated paper, coated and uncoated nonwovens, scrims, meshes, wovens, 
nonwovens, and perforated or porous films, and combinations thereof 
Different applications for the formed closure means will dictate ideal size 
and density of protrusions, as well as the selection of the substances 
used therewith. It is believed that the protrusion size, shape and 
spacing, the web material properties such as flexural modulus, material 
stiffness, material thickness, hardness, deflection temperature as well as 
the forming process determine the strength of the protrusion. A 
"threshold" protrusion stiffness is required to prevent premature 
activation of the closure means due to the weight of overlaying layers of 
sheets or other forces, such as forces induced by shipping vibrations, 
mishandling, dropping and the like. 
Inversion of protrusions minimizes protrusion spring back so that higher 
adhesion isn't necessary in order to prevent the failure of relatively 
weak seals. A resilient protrusion could be used, for example, where it is 
intended for the bond to be permanent, where aggressive adhesive overcomes 
spring back. Also, a resilient protrusion may be desirable where repeat 
use of the material is intended. 
FIG. 9 shows a preferred shape of the protrusions and valleys of closure 
means of the present invention, which enables protrusions to substantially 
invert and/or crush as a mode of deforming. The preferred shape minimizes 
protrusion fold-over and interference with substance placed in valleys 
between protrusions, or inside hollow protrusions, or both. Also, the 
preferred shape helps to ensure a repeatable, predictable, resistance to 
protrusion deformation. FIG. 9 shows that each protrusion is defined by a 
height dimension A and a base diameter dimension B. A preferred ratio of 
base diameter B to height A, which enables protrusions to substantially 
invert and/or crush without fold-over, is at least 2:1. 
FIG. 10 shows a suitable method for making a material such as the material 
30 useful in accordance with the present invention, which is generally 
indicated as 180 in FIG. 10. 
The first step comprises coating a forming screen with a first substance. 
The forming screen has a top surface and a plurality of recesses therein. 
The coating step applies the first substance to the top surface without 
bridging the recesses. A second step includes introducing a piece of 
material, which has a first side and a second side, onto the forming 
screen such that the first side is in contact with the first substance on 
the top surface of the forming screen. The first substance preferentially 
adheres to the first side of the piece of material. A third step includes 
forming the piece of material to create a plurality of hollow protrusions 
extending from the first side into the recesses of the forming screen. The 
plurality of hollow protrusions are spaced apart by valleys into which the 
first substance is transferred from the forming screen. The plurality of 
hollow protrusions are accurately registered with the first substance by 
use of a common transfer and forming surface. The first substance forms an 
interconnected layer in the valleys between the protrusions. 
Forming screen 181 is threaded over idler pulley 182 and a driven vacuum 
roll 184. Forming screen 181 is preferably a stainless steel belt, having 
the desired protrusion pattern etched as recesses in the belt. Covering 
the outer surface of vacuum roll 184 is a seamless nickel screen which 
serves as a porous backing surface for forming screen 181. 
For producing a pressure sensitive adhesive containing material, a 
substance 186, preferably hot melt adhesive, is coated onto forming screen 
181 by a substance applicator 188 while forming screen 181 rotates past 
the applicator. A web of material 190 is brought into contact with the 
substance coated forming screen at material infeed idler roll 192. Hot air 
is directed radially at material 190 by a hat air source 194 as the 
material passes over vacuum roll 184 and as vacuum is applied to forming 
screen 181 through vacuum roll 184 via fixed vacuum manifold 196 from a 
vacuum source (not shown). A vacuum is applied as the material is heated 
by hot air source 194. A formed, substance coated material 198 is stripped 
from forming screen 181 at stripping roll 200. Because the same common 
forming screen is used to transfer the substance to the material as is 
used to form the protrusion, the substance pattern is conveniently 
registered with the protrusions. 
Stainless steel forming screen 181 is a fabricated, seamed belt. It is 
fabricated in several steps. The recess pattern is developed by computer 
program and printed onto a transparency to provide a photomask for 
photoetching. The photomask is used to create etched and non-etched areas. 
The etched material is typically stainless steel, but it may also be 
brass, aluminum, copper, magnesium, and other materials including alloys. 
Additionally, the recess pattern may be etched into photosensitive 
polymers instead of metals. Suitable forming structures are described in 
greater detail in the above-referenced and above-incorporated Hamilton et 
al. and McGuire et al. patent applications. 
Materials of the foregoing variety when utilized as a closure means in 
accordance with the present invention may be unitarily formed and 
constructed as art of the body of the flexible storage bag either before, 
during, or after assemblage of the bag from its material components. 
Alternatively, such closure means may also be separately formed and joined 
to the body of the flexible storage bag either before, during or after 
assemblage of the bag. Such joining may be edge-wise or may be 
accomplished as a lamination or bonding of the material facially onto a 
superposed portion of the bag body, such lamination being particularly 
advantageous when it is desired to add additional thickness, stiffness, 
and/or resiliency to the region of the bag comprising the closure means. 
The material utilized for the closure means may be the same as or 
different from the material utilized to form the bag body either in 
dimensions or in composition. 
To facilitate separation of adhered or bonded overlying portions of the 
closure means material, various adaptations or modifications may be 
accomplished in terms of integration of the material into the overall 
structure of the flexible storage bag. For example, it may be desirable to 
provide extension tabs on opposing sides of the opening periphery to 
facilitate manual initiation of closure separation. It may also be 
desirable to leave a small but finite portion of the bag body immediately 
adjacent to the opening periphery free of closure material, such that 
there is a non-adherent rim of material which may be utilized to initiate 
material separation and hence opening of the flexible storage bag. The 
closure means 30 depicted in FIGS. 1-4 are consistent with the latter 
approach. 
In accordance with the present invention, the use of 
selectively-activatible adhesive materials for the closure means 30 
provides the user with an easy-to-operate closure means for closing and 
sealing an opening in a flexible storage bag. The closure means 30 is easy 
to manipulate with one or two hands, as the only dexterity required is to 
grasp or pinch the closure means with a pair of opposed digits to activate 
the material against an opposing surface of the bag body or closure means. 
Moving the grasping digits across the extent of the opening provides 
secure adhesion of the closure means across the extent of the opening, 
thereby converting the flexible bag from a semi-enclosed container to a 
fully closed container. Particularly when the closure means fully 
encircles the opening in the bag body, the closure means 30 is highly 
tolerant to misalignment as it will adhere to any opposing surface unlike 
mechanical closure mechanisms which typically require precise alignment of 
mating elements. 
The ability of the closure means to be activated by pinching or grasping 
superimposed portions of the bag body is particularly advantageous with 
flexible, conformable structures such as the flexible storage bags of the 
present invention. More particularly, such structures are yieldable under 
applied forces and accordingly, it would be difficult to activate a seal 
by exerting pressure upon the bag as a whole against a surface, 
particularly when filled, as such would tend to expel bag contents as 
sealing of the closure is attempted. Therefore, the use of a closure means 
as herein described permits secure, reliable sealing of even highly 
flexible storage bags. 
Because the closure means in a preferred configuration employs a layer of 
adhesive protected by a plurality of three-dimensional protrusions, rather 
than a three-dimensional mating pair of interlocking elements, it is 
possible to employ such a closure means successfully in a confined, 
non-parallel region of the bag body such as the region near the side seams 
24 and 26 without providing leakage sites such as the ends of the 
mechanical elements. Accordingly, the closure means 30 of the present 
invention provides additional security and confidence in the level of 
sealing obtained for situations where a leakproof seal is important. 
FIGS. 11 and 12 depict in greater detail the structure and operation of the 
secondary venting opening and closure means. FIG. 11 is an edge-on view of 
the flexible storage bag 10 shown in FIG. 3. Accordingly, the side edge 26 
shown in FIG. 3 forms the central line of the bag in FIG. 11. The flexible 
storage bag is shown in a condition wherein the primary opening along edge 
28 is open as shown in FIG. 2 so that the sidewalls of the bag are parted 
to highlight the view of opening 50. 
As shown in FIG. 11, the secondary venting opening 50 comprises a slit in 
the material of the bag body 20 which, when subjected to a slight pulling 
force normal to the direction of the slit, forms a somewhat elliptical 
opening. As used herein, the term "slit" is utilized to refer not only to 
openings formed by severing of the surrounding material but also to 
adjacent non-joined portions of surrounding material forming an elongated 
opening resembling a slit. In the embodiment depicted in FIG. 11 the 
secondary closure means 40 fully laterally surrounds the secondary venting 
opening 50. 
FIG. 12 depicts the flexible storage bag of FIG. 11 after the secondary 
venting opening 50 has been closed by the secondary closure means 40. As 
discussed above with the primary closure means 30, the closure means 40 
completely encircles the periphery of the opening 50. However, under some 
circumstances a closure means formed by a lesser degree of encirclement 
(such as, for example, a closure means disposed along only one side of 
edge 26 around opening 50) may provide adequate closure integrity. 
In accordance with the present invention, the secondary closure means 40 
comprises a selectively activatible adhesive-like material which bonds 
opposing material surfaces to one another across the secondary venting 
opening 50. Materials suitable for secondary closure means 40 are 
described above with regard to closure means 30. Therefore, as shown in 
FIG. 12 the secondary closure means 40 has been activated and adhesively 
bonded to material on the opposite side of the opening 50 to seal the 
opening. Correspondingly to the discussion above regarding the closure 
means 30, activation and sealing of the secondary closure means 40 malt 
also be accomplished simply by pinching or grasping the overlying regions 
of the bag body surrounding the secondary opening 50 over a broad enough 
area to surround the opening 50 with a sealed region of closure material. 
FIG. 13 is a view similar to that of FIG. 11 of a flexible storage bag 
according to FIG. 4. Accordingly, as shown in FIG. 13 the opening 50 is 
located within the region forming the closure means 30 for the primary 
opening along open edge 28. The portion of the primary closure means 30 
which at least partially, and preferably fully, surrounds the opening 50 
forms the secondary closure means analogous to the secondary closure means 
40 depicted in FIGS. 11 and 12. The closure means 30 thereby forms both 
the primary and secondary closure means for the primary opening (formed by 
open edge 28) and the secondary venting opening 50, although permitting 
independent activation of the closure means in order to selectively effect 
closure of either one or both openings as desired. 
With or without the desirable venting features of the present invention, 
the use of the selectively-activatible closure means of the present 
invention for the primary closure facilitates greater ease of venting or 
expelling air and/or free space above or around the contents prior to 
sealing by providing an easy-to-use sealing mechanism. Alternatively, the 
venting aspects of the present invention described above with regard to 
FIGS. 11-14 may be employed with conventional primary closure mechanisms 
including mechanical interlocking closures, although for maximum benefit 
is it presently preferred to utilized selectively-activatible closure 
means for both types of openings. 
FIG. 15 depicts another embodiment of a flexible storage bag in accordance 
with the present invention. The flexible storage bag 110 of FIG. 15 
includes a closure means 130 analogous to the closure means described with 
regard to the flexible storage bags of FIGS. 1-4, but also includes an 
additional feature to enable the bag to assume a self-supporting 
configuration to facilitate product access and product filling without 
manual support. 
While the flexible storage bags described above with regard to FIGS. 1-4 
and 11-14 provide many advantages compared with flexible storage bags and 
storage containers commonly available, it would further be desirable to 
adapt such a bag to be more self-supporting in use to additionally provide 
for greater ease of use. 
As utilized herein, the term "self-supporting" is utilized to refer to 
materials, structures, or containers which are capable of maintaining 
their orientation in a plane parallel to the direction of the force of 
gravity. For example, a self-supporting material, particularly a sheet 
material, may be held so that it extends upwardly parallel to the 
direction of the force of gravity and maintain its orientation without 
folding over or collapsing. Non-self-supporting materials typically will 
fold over or collapse and not be capable of being held parallel to the 
force of gravity (i.e., "vertically") unless they are held so that they 
extend downwardly from their point of support. Correspondingly, a 
self-supporting bag or container is capable of maintaining its orientation 
with surfaces extending upwardly from their base of support in opposition 
to the force of gravity without folding over upon itself or collapsing. 
In the embodiment of FIG. 15, the flexible storage bag 110 comprises two 
generally planar side panels 120, two generally planar, gusseted end 
panels 140, and a generally planar bottom panel 150, which panels form a 
semi-enclosed container having an opening defined by upper edge 128. Side 
panels 120 include side edges 122 and bottom edges 126, while end panels 
140 include bottom edges 148 and gussets of generally conventional design 
having converging base creases 142 and 144 and medial creases 146. In the 
configuration depicted in FIG. 15, the bag is in its self-supporting, open 
condition. 
As is known in the art, gusseted bags typically provide a self-supporting, 
open bag which may be readily filled or emptied with a minimum of 
difficulty. However, unlike most conventional gusseted bags the flexible 
storage bags of the present invention include a selectively-activatible 
closure means 130 as described above. Accordingly, in addition to being 
self-supporting the gusseted flexible storage bags 110 also provide the 
desirable sealing attributes described herein. 
The combination of gusseted bag design with sealing (and preferably 
re-sealing) technology is made possible by the use of the 
selectively-activatible closure means of the present invention. Unlike the 
flexible storage bags depicted in FIGS. 1-4, the gusseted bags include a 
plurality of creases in the material of the bag body which would be 
difficult if not impossible to effectively seal with mechanical 
interlocking seals, or by gathering the upper portion of the bag for a 
mechanical tie or binder. Since the closure means is selectively 
activatible and will adhere to any complementary surface, so long as the 
closure means encircles a sufficient proportion of the periphery of the 
bag opening the seams and pleats present in the bag walls (such as side 
edges 122 and medial creases 146) will all be securely adhered and sealed 
to provide the desired level of sealability. 
In addition to being self-supporting, gusseted flexible storage bags 110 
are also readily foldable or collapsible to provide easy storage occupying 
minimal space. FIG. 16 depicts a gusseted flexible storage bag 110 as 
shown in FIG. 15 but in a partially folded or collapsed condition. 
Accordingly, medial creases 146 have been pushed inwardly toward one 
another, bringing side edges 122 toward one another on opposite sides of 
the medial creases 146 and somewhat parallel to the base creases 142 and 
144 in their vicinity. Such a predictable folding feature independent of 
the closure means also permits the volume of the container to be 
diminished after the contents are inserted to minimize the amount of air 
and/or free space above or around the contents which is trapped within the 
bag after closure to minimize storage space of filled bags and to aid the 
effectiveness of the bag in preservation of perishable items. FIG. 17 
shows a gusseted flexible storage bag 110 in a more fully folded condition 
wherein folding continues until the bottom 150 is substantially parallel 
with the sides. Also depicted in FIG. 17 is the optional reinforcing 
bottom panel 155 which adds additional integrity and stability to the 
generally rectangular, planar bottom panel 150. 
The addition of additional reinforcement to the bottom panel lowers the 
center of gravity of the empty bag for greater stability prior to and 
during filling, increases the stiffness of the bottom of the bag for added 
stability in most circumstances filled or empty, and reduces the 
likelihood of the bottom of the bag bowing when filled with heavier 
contents. The inward folding of the flaps forming the bottom panel 150 of 
the bag body as shown in FIG. 18 also performs a similar role. The 
reinforcing panel may be of a similar material to the bag material or may 
be of a different more or less durable material, and is secured to the 
bottom panel by adhesive application or other suitable means. It is 
presently preferred that when a reinforcing panel is employed that it be 
placed on the exterior surface of the bottom panel rather than on the 
interior surface in order to provide support and reinforcement without 
adding additional surfaces, joints, and crevices on the interior of the 
bag where they may provide sites for trapping portions of the bag contents 
and creating cleaning difficulties. 
FIG. 18 depicts a bag similar to that of FIG. 17, but without the optional 
reinforcing panel on the bottom 150. In FIG. 18, therefore, the seam and 
folding structure of the bottom 150 is clearly visible. Such a folding 
configuration is typical of conventional folded, gusseted bags having a 
square or rectangular bottom and is sealed appropriately by adhesives, 
heat seals, or the like so as to provide a substantially liquid-tight and 
gas-tight bottom structure. 
FIG. 19 depicts a flexible storage bag typical of that shown in FIGS. 
15-18, but in a sealed condition such as after insertion of a product into 
the interior of the bag. Accordingly, the medial creases 146 of the 
gussets have been pushed inwardly from the configuration of FIG. 15 in a 
manner similar to that of FIG. 16. However, the closure means 130 has been 
subjected to activation by a user so that overlying superimposed regions 
of the closure means are adhesively bonded to one another to form a 
secure, substantially fluid- and vapor-impervious seal for the opening 
formed by the open edge 128 of the bag. In the preferred configuration 
shown in FIGS. 15-19, the closure means entirely encircles the open edge 
128 of the bag so that complete adhesion of the entire periphery is 
assured upon activation. 
As will become apparent by viewing the sequence of steps depicted in FIGS. 
15-21, the flexible sheet material utilized to form the body of the bag is 
sufficiently flexible and yieldable to accommodate the motion of the 
gusseted end panels 140 as they move between the open configuration of 
FIG. 15 and the closed configurations of FIGS. 19 and 21. More 
particularly, the end panels 140 are sufficiently flexible to fold or 
pleat upon themselves as needed to accommodate the folding inwardly or 
outwardly of the medial creases to accomplish activation of the closure 
means. 
To open the bag of FIG. 19, a user may grasp one pair of diagonally 
opposite edge creases 122 and pull them in diagonally opposite directions 
to initiate and propagate separation of the closure means in the central 
region. The other pair of diagonally opposite edge creases 122 may then be 
grasped and pulled in similar fashion to further propagate the separation 
of the closure means. Alternatively, marginal edges (which as mentioned 
above are preferably partially adhesive-free) of the bag above the closure 
means may be grasped and pulled apart. 
FIG. 20 depicts the closed and sealed bag of FIG. 19 with the top portion 
optionally folded over substantially parallel to the bottom 150, so that a 
stable stackable configuration is obtained whereupon other containers, 
articles, or the like may be stably placed upon the bag. Again, the 
flexible nature of the material of the bag body makes such a folding-over 
a viable option for efficient storage. The gusseted, pleated sidewall 
structure with spaced, defined corners adds additional integrity and 
stability to the filled bag, improving stackability in use and adding 
stability as well in terms of overturning or the like. 
While FIGS. 19 and 20 depict one approach to achieving closure of the 
flexible storage bag, the closure means of the present invention provides 
for an additional approach to closure. As shown in FIG. 20, the medial 
creases 146 of the gussets may be pulled outwardly from one another rather 
than pushed inwardly, so that a straight line closure of two substantially 
parallel facing surfaces may be obtained in similar fashion to the 
flexible storage bags of FIGS. 1-4. In this fashion closure may be 
achieved by a simple sweep of a hand across the entire upper open edge 128 
with a simpler line of sealing than if the gussets were maintained as 
shown in FIGS. 19 and 20. Like the bag of FIGS. 19 and 20, the bag sealed 
as shown in FIG. 21 may also be folded over to form a stable stackable 
configuration. As discussed above, it is the selectively-activatible 
adhesive nature of the closure means of the present invention which makes 
this dual-functionality, dual-mode closure, for pleated flexible storage 
bags a reality. 
Although the self-supporting flexible storage bags illustrated in the 
foregoing FIGS. 15-21 have been constructed of flexible sheet material 
along the lines of the approach typically taken for paper grocery-type 
bags, as illustrated for example in U.S. Pat. No. 584,555, issued Jun. 15, 
1897 to Lorenz, a wide variety of other constructions may be utilized in 
keeping with the self-supporting approach in conjunction with the use of a 
closure means in accordance with the present invention. Examples of such 
other illustrative bag designs include U.S. Pat. No. 3,970,241, issued 
Jul. 20, 1976 to Hanson, U.S. Pat. No. 5,061,500, issued Oct. 29, 1991 to 
Mendenhall, U.S. Pat. No. 5,195,829, issued Mar. 23, 1993 to Watkins et 
al., and U.S. Pat. No. 5,314,252, issued May 24, 1994 to Happ. Also 
illustrative is commonly-assigned U.S. Pat. No. 4,898,477, issued Feb. 6, 
1990 to Cox et al., the disclosure of which is hereby incorporated herein 
by reference. 
In addition to such use of sheet material folded and sealed to form the bag 
body, the bag may be constructed in any known and suitable fashion such as 
those known in the art for making such bags in commercially available 
form. Heat or adhesive sealing technologies may be utilized to join 
various components or elements of the bag to themselves or to each other. 
In addition, the bag bodies may be thermoformed, blown, or otherwise 
molded from a starting blank or sheet of material rather than reliance 
upon folding and bonding techniques to construct the bag bodies from a web 
or sheet of material. 
While particular embodiments of the present invention have been illustrated 
and described, it would be obvious to those skilled in the art that 
various other changes and modifications can be made without departing from 
the spirit and scope of the invention. It is therefore intended to cover 
in the appended claims all such changes and modifications that are within 
the scope of this invention.