HK1059919A - Bag with extensible handles - Google Patents

Description

Bag with extendable handle

Technical Field

The present invention relates to bags used to contain and handle various items in general, and more particularly to bags having an integral closure system.

Background

Bags, particularly flexible bags, are typically made from relatively inexpensive polymeric materials. Such bags have become widely used for containing and/or handling various items and/or materials. The term "flexible" as used herein refers to materials that are capable of flexing or bending (particularly repeatedly) because they are compliant or yieldable in response to externally applied forces that often occur during use of the bag. Thus, "flexible" is essentially in the opposite sense to the terms "inflexible," "rigid," or "unyielding" in response to external forces that often occur in use. Thus, the flexible materials and structures can be altered in shape and structure to accommodate external forces and conform to the shape of objects in contact therewith without compromising their integrity. For example, flexible bags may be used as liners for durable trash cans.

For storing or disposing of the material contained in the flexible bag, several techniques for closing the bag are known in the art. For example, twisted tethers are commonly used. However, the twisted tether requires a separate component from the trash bag, i.e., the twisted tether itself. The separate component may be lost or inadvertently discarded. Furthermore, twisted tethers have not met with great success in providing secure closure of the bag.

Another technique known in the art is to use sinusoidal edges at the bag opening. These edges may be overlapped and tied together to form a handle as described in U.S. patent US5,246,110 issued to Greyenstein on 9/21 1993. However, the sinusoidal edges that become handles hang unevenly over the top of any durable container lined with a flexible bag. This creates an uneven and unsightly appearance when the flexible bag is used. Furthermore, the stretch properties of the material forming the handle are generally equivalent to the equilibrium state (balance) of the bag being formed. Which prevents the handle from being pulled tight first during the tightening process and forms an easy-to-use means for closing the bag.

Another technique known in the art is to provide drawstrings around the top of the bag as described in US4778283 to Osborn, 10/18 1988. However, drawstring closures are expensive in use and often tear.

Commonly assigned U.S. patent application 09/336211 filed in Jackson, 1999, 6/18 and 09/336212 filed in Meyer et al, 1999, the disclosure of which is incorporated herein by reference, disclose flexible bags having a closure. In particular, a drawstring type closure, a drawable handle or a flap, a twisted tether or interlocking strap closure, an adhesive-based closure, an interlocking mechanical seal, a removable tether, or a strap and heat seal comprised of bag components are disclosed.

The present invention provides a seal for an easy to use flexible bag that is integral to the bag and takes advantage of the preferred material properties of the bag.

Disclosure of Invention

The present invention provides a bag comprising at least one sheet of flexible material forming a semi-enclosed container. The container has an opening defined by a perimeter. The bag has a filling direction substantially perpendicular to the opening. The bag has an enclosed region juxtaposed with the periphery. The enclosed region includes a first region and a second region. When the sheet of flexible material is subjected to an applied tensile force, the first region undergoes a substantially molecular-scale deformation and the second region initially undergoes a substantially geometric deformation. The closure zone of the bag may extend in the filling direction in response to such tensile forces. The stretching force may be applied substantially parallel to the filling direction.

Drawings

FIG. 1 is a plan view of a flexible bag according to the present invention in a closed, hollow condition;

FIG. 2 is a partial view of a polymeric film material of the flexible bag in a substantially relaxed state;

FIG. 3 is a partial view of the polymer film of FIG. 2 in a partially tensioned state;

FIG. 4 is a partial view of the polymer film of FIG. 2 in a more tensioned state;

FIG. 5 is a partial top plan view of another embodiment of a sheet material useful in the present invention;

FIG. 6 is a partial top plan view of the sheet of FIG. 5 in a partially tensioned state;

FIG. 7 is another embodiment of the bag of FIG. 1;

fig. 8 is a further embodiment of the bag of fig. 1.

Detailed Description

Fig. 1 shows one embodiment of a bag 10 according to the present invention. The bag 10 also has an opening 12 defined by a perimeter 14. Opposite the opening 12 is a bottom 16 of the bag 10. Although a bag 10 having only one opening 12 is shown, it is contemplated that bags 10 having more than one opening 12 of the same or different sizes are also within the scope of the present invention. Intermediate the opening 12 and the bottom 10 of the bag 10 is the body of the bag 10.

Juxtaposed with the opening 12 is an integral closure for closing the bag 10. The closure may completely seal the bag 10 to prevent loss of the contents during normal use, or simply loosely seal the bag 10 to minimize loss of the contents from the bag 10. As used herein, a closure is considered to be integral with the bag 10 if it is formed entirely of the raw material of the bag 10 and is not structurally modified from the body of the bag 10. Thus, it is believed that the stranded tether, drawstring closure, interlocking strap closure, and mechanical seal are not integral closures.

In the embodiment according to fig. 1, the bag 10 is made of a flexible material and comprises a body of the bag 10 formed from a sheet of flexible sheet material folded over itself along one crease line and bonded to itself along each side seam. It can be understood that: the bag 10 may be folded along other crease lines and may be bonded along other side seams. Alternatively, the bag 10 may be of unitary construction. The bag 10 may also be constructed from a continuous tubular sheet 52, thus having no side seams, and having a bottom seam of the bottom 16 instead of a crease line of the bottom 16.

It is conceivable that: the bag 10 according to the present invention may be of various sizes depending on the end use. For example, the pouch 10 according to the present invention may have a volume of only a few cubic centimeters for storing pills, coins, and the like. Alternatively, the bag 10 according to the invention may have a volume of a few litres for storing waste, such as yard waste.

The perimeter 14 of the bag 10 defines an opening 12 corresponding to the cross-section of the bag 10. Although a bag 10 with a constant cross-section is shown, it is understood that: bags 10 having varying cross-sections are also within the scope of the present invention. Although the bag 10 is shown as having a cross-section parallel to the plane defined by the opening 12 at any point throughout the depth of the bag 10, it will be appreciated that: also encompassed within the invention is a bag 10 having an inclined configuration with its cross-section disposed at an acute angular relationship relative to the plane of the opening 12.

Perpendicular to the plane of the opening 12 is a filling direction 24. The filling direction 24 is generally the direction of insertion and/or removal of the contents of the bag 10. Of course, it will be understood that: it is not necessary to place the contents into the bag 10 or remove the contents from the bag 10 in a direction that is completely consistent with and parallel to the filling direction 24, but the filling direction 24 represents the primary direction of filling or emptying the bag 10. When the bag 10 is opened, the radial direction is transverse to the filling direction 24. When the bag 10 is in a flat, closed condition, it lies laterally within the plane of the bag 10.

Although the drawings show a bag 10 having a generally straight perimeter 14, it will be appreciated that: bags 10 having sinusoidal perimeters are also well known in the art. The sinusoidal perimeter is used to provide a handle for traversing the opening 12 of the bag 10 while forming a closure. If a bag 10 having a peripheral edge 14 other than that shown in the figures is selected, the filling direction 24 is perpendicular to the cross-section of the bag 10 formed at the point of the peripheral edge 14 closest to the bottom 16 of the bag 10.

As used herein, closure zone 26 is the area of bag 10 juxtaposed with periphery 14. Enclosed region 26 may extend in a direction generally parallel to fill direction 24. The closure zone 26 comprises an area of the bag 10 that is extensible in response to applied tension. Importantly, the containment zone 26 has a greater degree of elastic extensibility than those regions of the bag 10 that do not include the containment zone 26. For bags 10 used as common trash receptacles in kitchens, it is preferred that the closure zone 26 have an elastic extensibility of approximately 10 to 15 centimeters. A larger bag 10 will generally require a larger closure zone 26 to transition to the opening 12 of the bag 10. The closure zone 26 may be extensible in either of two perpendicular directions in the plane of the bag 10, although the main direction of extensibility is generally parallel to the filling direction 24.

In a preferred embodiment, the containment region 26 is inspected in greater detail, and the containment region 26 completely circumscribes the opening 12 of the bag 10. However, it will be appreciated that: the closure zone 26 need not completely circumscribe the opening 12 of the bag 10. For example, the closure zone 26 may be directed toward opposing sections of the bag 10. In this embodiment, the closure zone 26 preferably subtends a total of 180 degrees, although a smaller closure zone 26 is sufficient for smaller bags 10. Basically, the closure zone 26 need only be subtended at sufficient circumference to form two or, if desired, multiple handles for closing the bag 10. Preferably equally divided between the sections as a whole. In this embodiment, each section of the closure zone 26 may function independently of the other sections and form a handle for extending locally parallel to the filling direction 24 and tied to the other sections of the closure zone 26. Between the sections of closure zone 26 are those portions of bag 10 that do not necessarily extend generally in a direction parallel to filling direction 24. These intermediate portions of the bag 10 may be relatively inextensible or stretchable in a circumferential direction generally parallel to the perimeter 14 of the bag 10.

Preferably, the closure zone 26 is optionally spaced from the periphery 14 in the filling direction 24 toward the bottom 16 of the bag 10. This spacing forms a peripheral region 28 near the peripheral edge 14 of the bag 10. The peripheral region 28 is disposed between the peripheral edge 14 of the bag 10 and the closure zone 26. The peripheral zone 28 has a lesser extensibility in the filling direction 24 than the enclosed zone 26. Preferably, the peripheral region 28 surrounds the perimeter 14 of the bag 10. However, as described above for the various configurations that are possible, if the containment zone 26 includes two or more sections of the bag 10, the peripheral zone 28 may be disposed between the edge of the section that includes the containment zone 26 and the peripheral edge 14.

The purpose of the peripheral zone 28 is to prevent excessive weakness from occurring at the peripheral edge 14 of the pouch 10. It is believed that this arrangement reduces the occurrence of undesirable tearing of the bag 10 caused by the divergent tear at the peripheral edge 14. The peripheral zone 28 has a width parallel to the filling direction 24, preferably at least 0.3 cm, more preferably at least 0.6 cm, most preferably at least 0.95 cm; and preferably less than 10 cm, more preferably less than 2.5 cm, and most preferably less than 1.9 cm. If the perimeter 14 of the bag 10 is sinusoidal, or another irregular shape, it is preferred that the perimeter region 28 be substantially parallel to the perimeter 14.

Referring to fig. 2-4, materials suitable for use in the present invention, such as those illustrated and described herein, and methods of making and characterizing the same, are described in commonly assigned U.S. patent No. US5518801, issued to Chappell et al, 5/21/1996, which is incorporated herein by reference. These materials are suitable for the closure zone 26 and possibly for the body of the bag 10 according to the invention. Particularly suitable materials include linear low density polyethylene having a thickness of 0.003 + -0.001 cm, available from the Heritage Bag Company of Atlanta, Georgia, or from the Clorox Company of SanFrancisco, California.

Referring to fig. 2-4, sheet 52 includes a "deformable network" of distinct regions. The term "deformable network" as used herein refers to a group of interconnected and associated regions that are capable of extending in a predetermined direction to a useful degree to provide the sheet 52 with an elastic-like behavior in response to an applied and subsequently released elongation. The deformable network includes at least a first region 64 and a second region 66. Sheet 52 includes a transition region 65 at the interface between first region 64 and second region 66. The transition zone 65 will exhibit a complex combination of the properties of both the first zone 64 and the second zone 66. It can be appreciated that: each of the embodiments of the sheet material 52 suitable for use in the present invention has a transition zone; however, these materials are defined by the properties of the sheet 52 in the first and second regions 64, 66. Thus, the following description will focus only on the properties of the sheet 52 in the first and second regions 64, 66, since it is not dependent on the complex properties of the sheet 52 in the transition region 65.

The sheet 52 has a first surface 52a and an opposing second surface 52 b. In the preferred embodiment shown in fig. 2, the deformable network includes a plurality of first regions 64 and a plurality of second regions 66. The first region 64 has a first axis 68 and a second axis 69, wherein the first axis 68 is preferably longer than the second axis 69. First axis 68 of first region 64 is substantially parallel to longitudinal axis "L" of sheet 52, and second axis 69 is substantially parallel to transverse axis "T" of sheet 52. Preferably, the second axis of the first region 64 (the width of the first region 64) is about 0.01 inches to about 0.5 inches, more preferably about 0.03 inches to about 0.25 inches. The second region 66 has a first axis 70 and a second axis 71. First axis 70 is substantially parallel to the longitudinal axis of sheet 52 and second axis 71 is substantially parallel to the transverse axis of sheet 52. Preferably, the second axis of the second region 66 (the width of the second region 66) is about 0.01 inches to about 2.0 inches, more preferably about 0.125 inches to about 1.0 inches. In the preferred embodiment of fig. 2, first zone 64 and second zone 66 are substantially linear and extend continuously in a direction substantially parallel to the longitudinal axis of sheet 52.

The first zone 64 has a modulus of elasticity E1 and a cross-sectional area A1. Second zone 66 has a modulus of elasticity E2 and a cross-sectional area A2.

In the illustrated embodiment, the sheet 52 is "formed" such that, when subjected to an applied axial elongation in a direction substantially parallel to the longitudinal axis, the sheet 52 exhibits a resistive force along the axis, which in the case of the illustrated embodiment is substantially parallel to the longitudinal axis of the web. The term "formed" as used herein refers to the formation of a desired structure or geometry on a sheet 52 that substantially retains the desired structure or geometry in the absence of any externally applied elongation or force. The sheet 52 of the present invention is comprised of at least a first region 64 and a second region 66, wherein the first region 64 is visually distinguishable from the second region 66. The term "visually distinguishable" as used herein refers to a characteristic of sheet 52 that is readily identifiable to the normal naked eye when sheet 52 or an object containing sheet 52 is subjected to normal use. The term "surface-pathlength" as used herein refers to a measure of the topographical surface along the area in question in a direction substantially parallel to the axis. Methods of determining the surface path length of each region can be found in the test methods section of the Chappell et al patent referenced and incorporated above.

Methods of forming such sheets 52 for use in the present invention include, but are not limited to: embossing, thermoforming, high pressure hydroforming, or casting with engaging platens or rollers. Although the entire portion of web 52 has been subjected to the forming operation, the present invention may in practice form only a portion thereof, such as the portion of material that comprises bag body 10, as will be described in greater detail below.

In the preferred embodiment shown, the first region 64 is substantially flat. That is, the material in first zone 64 is in substantially the same condition both before and after web 52 undergoes the forming step. The second region 66 includes a plurality of raised ribs 74. The ribs 74 may be made convex, concave (debossed) or a combination of the two. Rib-like members 74 have a first or major axis 76 that is substantially parallel to the transverse axis of web 52, and a second or minor axis 77 that is substantially parallel to the longitudinal axis of web 52. The length parallel to the first axis 76 of the rib 74 is at least equal to, and preferably longer than, the length parallel to the second axis 77. Preferably, the ratio of the first axis 76 to the second axis 77 is at least about 1: 1 or greater, and more preferably at least about 2: 1 or greater.

The ribs 74 in the second region 66 may be separated from one another by unformed regions. Preferably, the ribs 74 are adjacent to each other and separated by unformed areas of less than 0.10 inches measured perpendicular to the major axis 76 of the ribs 74, and more preferably, the ribs 74 are continuous with substantially no unformed areas therebetween.

The first region 64 and the second region 66 each have a "projected path length". The term "projection path length" as used herein refers to the shadow length of the area that is projected by the parallel light. The projected path length of the first region 64 and the projected path length of the second region 66 are equal to each other.

First region 64 has a surface-path length L1 that is less than the surface-path length L2 of second region 66, as measured by surface topography (topographicaly) in a direction parallel to the longitudinal axis of web 52, with the web in a relaxed state. Preferably, the surface pathlength of the second region 66 is at least about 15% greater than that of the first region 64, more preferably at least about 30% greater than that of the first region 64, and most preferably at least about 70% greater than that of the first region 64. Generally, the greater the surface pathlength of the second region 66, the greater the elongation of the web before encountering a force wall. Suitable techniques for measuring the surface pathlength of such materials are described in the Chappell et al patent referenced and incorporated above.

Sheet material 52 exhibits a reduced "poisson lateral contraction effect" substantially less than other identical base webs of similar material composition. Methods for measuring the poisson lateral contraction effect of a material may be found in the test methods section of the Chappell et al patent, referenced and incorporated above. Preferably, webs suitable for use in the present invention have a Poisson's transverse contraction effect of less than about 0.4 when the web is subjected to about 20% elongation. Preferably, the web exhibits a poisson lateral contraction effect of less than about 0.4 when the web is subjected to an elongation of about 40, 50 or even 60%. More preferably, the poisson lateral contraction effect is less than about 0.3 when the web is subjected to about 20, 40, 50 or 60% elongation. The poisson lateral contraction effect of such a web is determined by the amount of web material occupied by the first and second zones 66, respectively. As the area of the sheet 52 occupied by the first region 64 increases, the poisson lateral contraction effect also increases. Conversely, as the area of sheet 52 occupied by second region 66 increases, the poisson lateral contraction effect decreases. Preferably, the percentage of the area of the sheet 52 occupied by the first zone is from about 2% to about 90%, more preferably from about 5% to about 50%.

Prior art sheets 52 having at least one layer of elastomeric material typically have a large Poisson cross-directional contraction effect, i.e., the sheet will "neck" when elongated in response to an applied force. The web material used in the present invention can be designed to be moderate if not substantially eliminate the poisson lateral contraction effect.

For sheet 52, the direction of applied axial elongation D, indicated by arrow 80, is substantially perpendicular to the first axis 76 of the ribs 74. The rib-like elements 74 are capable of straightening or geometric deformation in a direction substantially perpendicular to their first axes 76 to enable the web 52 to extend.

When the web of sheet material 52 is subjected to an applied axial elongation D, indicated by arrow 80, the first zone 64 having a shorter surface path length L1 provides a substantial portion of the initial resistance force P1 as a result of the molecular-scale deformation to the applied elongation. At this stage, the ribs 74 in the second region 66 undergo geometric deformation, or unbending, and provide minimal resistance to applied elongation. In transitioning to the next stage, the ribs 74 become flush (i.e., coplanar) with the applied elongation. That is, the second region 66 is exhibiting a change from geometric deformation to molecular-scale deformation. This is the beginning of the force wall. In the stage of fig. 4, the ribs 74 in the second region 66 become substantially aligned with (i.e., coplanar with) the plane of applied elongation, i.e., the second region 66 has reached the limit of its geometric deformation and begins to resist further deformation via molecular-scale deformation. Now as a result of the molecular-scale deformation, the second region 66 acts as a second resistance force P2 to further applied elongation. The elongation-resisting forces created by both the molecular-scale deformation of first region 64 and the molecular-scale deformation of second region 66 form a total resisting force PT that is greater than the resisting forces provided by the molecular-scale deformation of first region 64 and the geometric deformation of second region 66.

When (L1+ D) is less than L2, resistance P1 is substantially greater than resistance P2. When (L1+ D) is less than L2, the first region 64 provides an initial resistance P1, which generally satisfies the following equation:

p1 ═ (a1 × E1 × D)/L1 when (L1+ D) is greater than L2, the first and second regions 66 provide a resultant total resistance PT to applied elongation D, which generally satisfies the following formula:

PT＝(A1×E1×D)/L1+(A2×E2×|L1+D-L2|)/L2

the maximum extension that occurs in the stages corresponding to figures 2-3 is the "effective extension" of the formed web material before the stage shown in figure 4 is reached. The effective elongation corresponds to the distance that the second region 66 undergoes geometric deformation. The range of effective elongation may vary from about 10% to 100% or more and the extent to which surface path length L2 in second region 66 exceeds surface path length L1 in first region 64 and the base film component may be controlled to a greater extent. The term "effective elongation" is not intended to imply a limitation on the elongation that the web of the present invention may experience, as there are applications where an amount of elongation in excess of the effective elongation is desired.

When the sheet 52 is subjected to an applied elongation, the sheet 52 exhibits an elastic-like behavior unless the sheet 52 extends beyond the yield point, as the sheet 52 extends in the direction of the applied elongation and returns to its substantially relaxed state once the applied elongation is removed. The sheet 52 can withstand multiple cycles of applied elongation without losing its ability to substantially recover. Thus, once the applied elongation is removed, the web is able to return to its substantially relaxed state.

While the sheet material 52 may readily and reversibly extend in the direction of the applied axial elongation (in a direction substantially perpendicular to the first axis of the rib-like members 74), the web material does not readily extend in a direction substantially parallel to the first axis of the rib-like members 74. The formation of the ribs 74 allows the ribs 74 to geometrically deform in a direction substantially perpendicular to a first or major axis of the ribs 74, while requiring substantial molecular-scale deformation to extend in a direction substantially parallel to the first axis of the ribs 74.

The amount of applied force required to extend the web depends on the composition and cross-sectional area of the sheet material 52 and the width and spacing of the first zones 64, with narrower and widely spaced first zones 64 requiring lower applied extension forces to achieve the desired elongation for a given composition and cross-sectional area. The first zone 64 preferably has a first axis (i.e., length) greater than a second axis (i.e., width) of the first zone 64, with a preferred length to width ratio of about 5: 1 or greater.

The depth and number of repetitions of the rib-like elements 74 can also be varied to control the effective elongation of the web suitable for the sheet 52 of the present invention. If there is an increase in the formed height or extent imparted to the ribs 74 for a given number of repetitions of the ribs 74, the effective elongation may increase. Likewise, if the number of repetitions of the rib 74 is increased for a given formed height or extent, the effective elongation may be increased.

By applying such materials to the flexible bag 10 of the present invention, several functional properties can be controlled. The functional properties are the resistance exerted by the sheet 52 against applied elongation and the effective elongation of the sheet 52 before encountering the force wall. The resistance to applied elongation exerted by the sheet 52 is a function of the material (e.g., composition, molecular structure and orientation, etc.) and cross-sectional area, as well as the percentage of the projected surface area of the sheet 52 occupied by the first regions 64. The greater the percentage of sheet material 52 occupied by the first zone 64, the greater the resistance the web exerts against the applied elongation for a given material composition and cross-sectional area. The percentage of the sheet 52 that the first regions 64 cover is determined in part, if not entirely, by the width of the first regions 64 and the spacing between adjacent first regions 64.

The effective elongation of the web material is determined by the surface-path length of the second zone 66. The surface-pathlength of the second zone 66 is determined at least in part by the spacing of the rib-like elements 74, the number of repetitions of the rib-like elements 74, and the depth of formation of the rib-like elements 74 measured perpendicular to the plane of the web material. Generally, the greater the surface-path length of the second zone 66, the greater the effective elongation of the web material.

As discussed above with reference to fig. 2-4, when the ribs 74 of the second regions 66 undergo geometric movement, the sheet 52 initially exhibits some resistance to elongation provided by the first regions 64. As the ribs 74 transition into the plane of the first region of material 64, increased resistance to elongation manifests itself as the entire sheet 52 undergoes molecular-scale deformation. Thus, sheets 52 of the type shown in FIGS. 2-4 and described in the above-referenced and incorporated Chappell et al patent provide the performance advantages of the present invention when formed into a closed container such as the flexible bag 10 of the present invention.

The sheet 52 used in the present invention as shown in fig. 2-4 exhibits a three-dimensional cross-sectional shape in which the sheet 52 is deformed outwardly (in a relaxed state) from the major plane of the sheet 52. This provides additional surface area for gripping and eliminates the gloss normally associated with substantially flat, smooth surfaces. The three-dimensional ribs 74 also provide a "cushiony" feel when the bag 10 is grasped in one hand, also contribute to the desired feel relative to conventional bag 10 materials, and allow for an improved thickness feel and durability. The additional texturing also reduces the noise generated by certain types of film materials, causing an audible sensation of comfort.

Suitable mechanical methods of forming the raw material into a web suitable for use in the sheet material 52 of the present invention are well known in the art and are disclosed in the aforementioned Chappell et al patent and the commonly assigned U.S. patent US5650214 to Anderson et al, 7-month-22-1997, the disclosure of which is incorporated herein by reference.

Referring now to FIG. 5, other patterns for the first and second regions 66 may also be used with sheeting 52 suitable for use in the present invention. The sheet 52 is shown in a substantially relaxed state in fig. 5. The sheet 52 has two centerlines, i.e., a longitudinal centerline, which is also referred to hereinafter as an axis, line, or direction "L"; a transverse or transverse centerline, which is also referred to hereinafter as axis, line or direction "T". The transverse centerline "T" is generally perpendicular to the longitudinal centerline "L". Materials of the type described in fig. 5-6 are described in detail in the aforementioned Anderson et al patent.

As described above with respect to fig. 2-4, sheet 52 includes a "deformable network" of distinct regions. The deformable network includes a plurality of first regions 64 and a plurality of second regions 66 that are visually distinct from one another. Sheet 52 also includes a transition zone 65 at the interface between first zone 64 and second zone 66. The transition zone 65 will have a complex combination of the behavior of both the first zone 64 and the second zone 66, as described above.

Sheet 52 has a first surface (facing the reader in fig. 5-6) and an opposing second surface (not shown). In the preferred embodiment of fig. 5-6, the deformable network includes a plurality of first regions 64 and a plurality of second regions 66. A portion of the first region 64, generally designated 61, is substantially linear and extends in a first direction. The remainder of the first region, generally designated 62, is substantially linear and extends in a second direction substantially perpendicular to the first direction. Although it is preferred that the first direction is perpendicular to the second direction, other angular relationships between the first direction and the second direction are also suitable as long as the first regions 61 and 62 intersect each other. Preferably, the angle between the first and second directions is in the range of about 45 ° to about 135 °, with 90 ° being most preferred. The intersection of the first regions 61 and 62 forms a boundary, indicated by the dashed line 63 in fig. 5, which completely surrounds the second region 66.

Preferably, the width 68 of the first region 64 is about 0.01 inches to about 0.5 inches, and more preferably about 0.03 inches to about 0.25 inches. However, other width dimensions are also suitable for the first region 64. The second region 66 is square in shape because the first regions 61 and 62 are perpendicular to each other and are equally spaced. However, other shapes are suitable for the second region 66 and may be achieved by varying the spacing between the first regions 64 and/or the arrangement of the first regions 61 and 62 relative to each other. The second region 66 has a first axis 70 and a second axis 71. The first axis 70 is substantially parallel to the longitudinal axis of the web material 52 and the second axis 71 is substantially parallel to the transverse axis of the web material 52. The first zone 64 has a modulus of elasticity E1 and a cross-sectional area A1. Second zone 66 has a modulus of elasticity E2 and a cross-sectional area A2.

In the embodiment shown in fig. 2-6, the first region 64 is substantially flat. That is, the material in first zone 64 is in substantially the same condition before and after the forming step that web 52 undergoes. The second region 66 includes a plurality of raised ribs 74. The ribs 74 may be raised, recessed, or a combination thereof. The rib-like members 74 have a first or major axis 76 generally parallel to the longitudinal axis of the web 52 and a second or minor axis 77 generally parallel to the transverse axis of the web 52.

The ribs 74 in the second regions 66 may be spaced from one another by unformed regions that are not substantially raised or recessed, or simply formed as spaced regions. Preferably, the ribs 74 are adjacent to each other and are separated by unformed areas of less than 0.01 inches measured perpendicular to the major axis 76 of the ribs 74, and more preferably, the ribs 74 are substantially free of unformed areas and are continuous.

The first region 64 and the second region 66 each have a "projected path length". The term "projection path length" as used herein refers to the shadow length of the area that is projected by the parallel light. The projected path length of the first region 64 and the projected path length of the second region 66 are equal to each other.

The first regions 64, measured in surface topography in the parallel direction, have a surface-path length L1, which is less than the surface-path length L2 of the second regions 66 when the web is in a relaxed state. Preferably, the surface pathlength of the second region 66 is at least about 15% greater than the first region 64, more preferably at least about 30% greater than the first region 64, and most preferably at least about 70% greater than the first region 64. Generally, the greater the surface-path length of the second region 66, the greater the amount of elongation of the web before encountering the force wall.

For the web material 52, the direction of applied axial elongation D, indicated by arrow 80 in FIGS. 5-6, is substantially perpendicular to the first axis 76 of the rib-like members 74. This is due to the fact that the rib-like members 74 are capable of straightening or geometrically deforming in a direction substantially perpendicular to their first axes 76 to allow for extension in the web 52.

Referring to fig. 6, as the web 52 undergoes an applied axial elongation D, represented by arrow 80 in fig. 5-6, the first zone 64 having a shorter surface path length L1 provides a majority of the initial resistance P1 to the applied elongation corresponding to stage I as a result of molecular-scale deformation. Also in phase I, the ribs 74 in the second regions 66 undergo geometric deformation, or unbending, and provide minimal resistance to applied elongation. In addition, the shape of the second region 66 is changed as a result of the movement of the net structure formed by crossing the first regions 61 and 62. Thus, as web 52 undergoes an applied elongation, first regions 61 and 62 undergo a geometric deformation or bending, thereby changing the shape of second region 66. The second region 66 extends or lengthens in a direction parallel to the direction of applied elongation and folds or contracts in a direction perpendicular to the direction of applied elongation.

The various components suitable for constructing the flexible bag 10 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 non-woven fabric, 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. These materials may comprise a single component or layer, or may be a composite structure of multiple materials.

Once the desired sheet 52 is manufactured in any desired and suitable manner, including all or a portion of the materials used for the body of the bag 10, the bag 10 may be constructed in any known and suitable manner, such as those known in the art for manufacturing bags 10 in commercially available forms. Thermal, mechanical, or adhesive sealing techniques may be used to join the various components or elements of the bag 10 to themselves or to one another. Further, rather than relying on folding and bonding techniques to construct the body of the bag 10 from a web or sheet of material, the body of the bag 10 may be thermoformed, blown, or molded. Two recent united states patents, US5554093 to Porchia et al, 9/10/1996 and US5575747 to Dais et al, 11/19/1996, illustrate the state of the art with respect to flexible storage bags 10 that are generally similar in structure to those shown in those figures, but are of a common type.

One benefit of having a containment zone 26 made of the foregoing material comprising two distinct regions is: the ribs of the second region 66 provide an enhanced tactile feel and gripping surface for tying together opposite sides of the closure region 26. Which reduces the likelihood of the bag 10 falling out of the ground or being mishandled, particularly when the contents are large or heavy. As will be apparent to those skilled in the art: for the above embodiment, the ribs 74 are oriented substantially perpendicular to the fill direction 24. This arrangement not only provides a good texture to closure zone 26, but also provides a direction of stretch of closure zone 26 parallel to fill direction 24.

Examples of the invention

The exemplary bag 10 of fig. 1 has an overall dimension of 84 centimeters oriented parallel to the filling direction 24 and an overall transverse dimension of 61 centimeters in a flat state. It is contemplated that the bag 10 may be divided into four regions, each region extending completely around the bag 10. The zones are spaced apart from each other in the filling direction 24. The bag 10 may be made of 0.019 cm thick polyethylene.

The first region 28 is a peripheral region 28. The peripheral region 28 is close to the periphery 14 of the bag 10 and does not induce extensibility (induced extensibility) other than that inherent in the raw material. The second zone 26 is a closed zone 26. The closure zone 26 is adjacent the peripheral zone 28 and is disposed toward the bottom 16 of the bag 10. Closure zone 26 has an induced extensibility that is oriented in a fill direction 24, represented by arrow 80. The third zone 30 is adjacent to the second zone 26 and has an induced extensibility that is oriented in the cross direction indicated by arrow 80. The fourth zone 32 is adjacent the bottom 16 of the bag 10 and has no induced extensibility as does the first zone 28. The first and fourth regions 28, 32 that do not have induced extensibility have dimensions of 1.3 and 6.4 centimeters, respectively, in the fill direction 24. In the filling direction 24, the second region 26 has a dimension of 55.9 cm, while the third region 30 has a dimension of 20.3 cm. The extensibility may be about 40% of the overall dimension of the bag 10 parallel to the filling direction 24, although greater or lesser extensibility may also be suitable.

Referring to fig. 7, a second example of a bag 10 is shown that represents another embodiment of the present invention. The bag 10 has a volume of 49.2 litres and an overall dimension in the filling direction 24 of 75 centimetres and a transverse dimension when flat of 61 centimetres. The bag 10 has the four regions described above. The first region 28 is a peripheral region 28. The peripheral zone 28 is adjacent to the peripheral edge 14 and has a dimension of 4.5 cm in the filling direction 24 and no induced extensibility. The second zone 26 is a closed zone 26. The closure zone 26 is located adjacent the first zone and toward the bottom 16 of the bag 10. The second region 26 has an induced extensibility in the fill direction 24 as indicated by arrow 80 and a dimension in the fill direction 24 of 32.4 centimeters. The third zone 30 is adjacent to the second zone and has an extensibility in the cross direction as indicated by arrow 80 and a dimension in the filling direction 24 of 33.0 centimeters. The fourth region 32, which is adjacent the bottom 16 of the bag 10, has no induced extensibility and has a dimension in the fill direction 24 of 5.1 centimeters. Superimposed on the first and second zones 28, 26 is a fifth zone 34 having an extensibility oriented at 45 ° relative to the filling direction indicated by arrow 80. The fifth zone 34 has a dimension of 32.4 cm in the filling direction 24. 45 ° extensibility provides the benefit of greater strength and elimination of over-extensibility that occurs in use. Moreover, this arrangement allows the sheet 52 to be pulled from the center to the edges of the bag 10. Although the bag 10 of fig. 7 has the fifth region 34 at a 45 ° angular relationship relative to the filling direction 24, in fact, such fifth region 34 may have an angle of 22 ° to 67 ° and still retain the benefits described above. This arrangement retains the benefits of having the material stretch in the fill direction 24 to enable a handle to be formed to close the bag 10.

Referring to fig. 8, a third exemplary bag 10 is shown. The bag 10 has the same overall dimensions, volume and peripheral area 28 as the bag 10 of figure 7. The bag 10 of fig. 8 alternates regions of induced extensibility 38 and regions of induced extensibility 39 that do not have an extensibility beyond that of the raw material. The region of induced extensibility 38 has an extensibility parallel to the filling direction 24 indicated by arrow 80. The stretch-inducing regions 38 provide a closure system for the bag 10. The alternating regions extend from the perimeter 14 of the bag 10 to the bottom 16 of the bag 10 and are oriented with the longitudinal axis parallel to the filling direction 24. The width of the regions 38, 39 may range from 0.6 to 3.0 centimeters or more. The width is parallel to the transverse direction. The width of the regions 38, 39 may be equal or unequal. As shown by the two examples above, either or both of the perimeter 14 and bottom 16 of the pouch 10 may optionally have a continuous peripheral section with no induced extensibility.

Claims (10)

1. A pouch comprised of at least one sheet of flexible material constituting a semi-enclosed container having an opening defined by a perimeter, said pouch having a fill direction generally perpendicular to said opening, said pouch comprising a closure zone juxtaposed with said perimeter, said closure zone comprising a first zone and a second zone, said first zone undergoing a substantially molecular-scale deformation and said second zone initially undergoing a substantially geometric deformation when said sheet of material is subjected to an applied tensile force, characterized in that said closure zone of said pouch is extensible in said fill direction in response to a tensile force applied generally parallel to said fill direction.

2. The bag of claim 1 wherein the bag has a bottom opposite the opening, the closure zone not intersecting the bottom of the bag.

3. A flexible bag according to claims 1 and 2, wherein the closure zone surrounds the opening of the bag.

4. A flexible bag according to claims 1, 2 and 3, wherein said first region and said second region are visually distinguishable from one another.

5. The flexible bag of claims 1, 2, 3, and 4, wherein said second region comprises a plurality of raised ribs, each of said raised ribs having a major axis and a minor axis orthogonal thereto, wherein said major axis is substantially perpendicular to said filling direction.

6. A flexible bag according to claims 1, 2, 3, 4 and 5, wherein said closure zone is spaced from said peripheral edge by a peripheral zone adjacent said peripheral edge, said peripheral zone having no induced elasticity.

7. A bag constructed from at least one sheet of flexible material constituting a semi-enclosed container having an opening defined by a periphery, the bag having a filling direction substantially perpendicular to the opening, the bag comprising a closure zone juxtaposed with the periphery, the closure zone comprising a first zone and a second zone, said first region undergoing a substantially molecular-scale deformation and said second region initially undergoing a substantially geometric deformation when said sheet of material is subjected to an applied tensile force, wherein the closure zone of the bag is extensible in the filling direction in response to a tensile force applied generally parallel to the filling direction, the enclosed region also includes a region that extends at an angle of approximately 22 to 67 degrees relative to the fill direction in response to an applied tensile force at the same angle of approximately 22 to 67 degrees relative to the fill direction.

8. The bag of claim 7 wherein the bag has a bottom opposite the opening, the bag having a second region with induced extensibility juxtaposed with the closure region and disposed toward the bottom of the bag, the second region being extensible in a direction perpendicular to the filling direction in response to an applied tensile force in the same direction substantially perpendicular to the filling direction.

9. The bag of claim 8, wherein the second region does not intersect the bottom of the bag.

10. The bag of claims 7, 8 and 9, wherein the angle is 95 degrees relative to the filling direction.