WO2020263727A1

WO2020263727A1 - Flexible container with increased effective hoop strength

Info

Publication number: WO2020263727A1
Application number: PCT/US2020/038893
Authority: WO
Inventors: Colmar WOCKE
Original assignee: Dow Global Technologies Llc
Priority date: 2019-06-28
Filing date: 2020-06-22
Publication date: 2020-12-30

Abstract

Embodiments of a flexible container (1) are provided. The flexible container include a package body formed from at least one flexible panel shaped with a plurality of seals, thereby enclosing an interior of the container. The at least one flexible panel is formed from a flexible film (10). Further, the flexible film includes a microchannel film (80) formed from a matrix of a thermoplastic material and having a plurality of channels (90) disposed in parallel in said matrix from a first end to a second end of said microchannel film. Additionally, at least one of the plurality of seals is a spine seal (26) disposed along an axial length of the container and the flexible film is oriented such that the channels (90) are aligned with the spine seal (26).

Description

FLEXIBLE CONTAINER WITH INCREASED EFFECTIVE

HOOP STRENGTH

CROSS REFERENCE TO RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional Patent Application No.

62/868,253, filed on June 28, 2020, the entire disclosure of which is hereby incorporated by reference.

TECHNICAL FIELD

[0002] Embodiments of the present disclosure generally relate to flexible product packaging and film arrangements for increased effective hoop strength. More specifically, embodiments of the present disclosure relate to flexible packages comprising a microchannel film with the channels aligned with at least one spine seal forming the flexible container.

BACKGROUND

[0003] A variety of liquid foodstuffs and other consumer goods are packaged for storage or transport in sealed flexible packaging. However, the sealed flexible packages must undergo a series of validation tests so as to verify that the packaging will be able to withstand transport to and usage by the end consumer. Specifically, many pouched articles are tested with a drop height impact test where the package is dropped from a defined height onto a hard surface to verify that the package structure and seals will withstand a similar fall or impact during transport and/or storage. However, failure of the packaging seals and/or the packaging structure proximate the seal is common during such testing. Failure of traditional packaging occurs because the contents, such as a liquid, within the sealed flexible packaging applies a force to the interior of the packaging upon contact with the hard surface and may rupture the packaging.

[0004] Previous solutions to overcome this problem have included increased strength throughout the packaging structure to reinforce the areas that traditionally experience failure. Specifically, the thickness of the material forming the sealed flexible packaging is increased throughout the package to ensure that the point of the seals/packaging receiving the highest forces during a drop event are capable of withstanding impact. This leads to utilization of unnecessary material volume and waste. [0005] Accordingly, there remains a need for a sealed flexible packaging that is capable of withstanding a drop event without bulking the thickness of the packaging material uniformly throughout the sealed flexible packaging.

SUMMARY

[0006] Embodiments of the present disclosure are directed to flexible containers, such as a stand-up pouch or a pillow pouch formed with a microchannel film oriented such that channels align with spine seals along the edges of the packaging to lessen packaging rupture when dropped.

[0007] In accordance with one embodiment, a flexible container is provided. The flexible container comprises a package body formed from at least one flexible panel shaped with a plurality of seals, thereby enclosing an interior of the container. The at least one flexible panel is formed from a flexible film. The flexible film comprises a microchannel film. The microchannel film comprises (a) a matrix comprising a thermoplastic material comprising a polyolefin, and (b) a plurality of channels disposed in parallel in said matrix from a first end to a second end of said microchannel film. Further, at least one of the plurality of seals is a spine seal disposed along an axial length of the container and the flexible film is oriented such that the channels are aligned with the spine seal.

[0008] In accordance with another embodiment, a flexible container is provided. The flexible container comprises a package body formed from at least one flexible panel shaped with a plurality of seals, thereby enclosing an interior of the container. The at least one flexible panel is formed from a flexible film having multiple layers. The flexible film comprises a sealant layer and a substrate layer; wherein the substrate layer comprises a microchannel film. The microchannel film comprises (a) a matrix comprising a thermoplastic material comprising a polyolefin, and (b) a plurality of channels disposed in parallel in said matrix from a first end to a second end of said microchannel film. Further, at least one of the plurality of seals is a spine seal disposed along an axial length of the container and the flexible film is oriented such that the channels are aligned with the spine seal.

[0009] In accordance with yet another embodiment, a method of increasing effective hoop strength of a heat-sealed polymeric container is provided. The method comprises forming the polymeric container from a flexible film comprising a microchannel film. The microchannel film comprises (a) a matrix comprising a thermoplastic comprising a polyolefin, and (b) at least one or more channels disposed in parallel in said matrix from a first end to a second end of said microchannel film, wherein said microchannel film comprise from 10 to 90 percent by volume of voidage, based on the total volume of the microchannel film. Further, the heat-sealed polymeric container comprises forming at least one spine seal along an axial length of the container and the flexible film is oriented such that the channels are aligned with the spine seal.

[0010] These and additional features provided by the embodiments of the present disclosure will be more fully understood in view of the following detailed description, in conjunction with the drawings.

BRIEF DESCRIPTION OF THE DRAWINGS

[0011] The following detailed description of specific embodiments of the present disclosure can be best understood when read in conjunction with the drawings enclosed herewith.

[0012] FIG. 1 is a schematic view of a flexible container according to one or more embodiments of the present disclosure.

[0013] FIG. 2A is a schematic view of a flexible container according to one or more embodiments of the present disclosure.

[0014] FIG. 2B is an exploded view of the flexible container according to FIG. 2A.

[0015] FIG. 3 is a top view of a microchannel film according to one or more embodiments of the present disclosure.

[0016] FIG. 4 is a longitudinal-sectional view of the microchannel film according to FIG 3.

[0017] FIG. 5 is a cross-sectional view of the microchannel film according to FIG 3.

[0018] FIG. 6 is an elevated view of the microchannel film according to FIG 3.

[0019] FIG. 7 is a transverse direction tensile stress-strain graph of a flexible multilayer film according to one or more embodiments of the present disclosure.

[0020] FIG. 8 is a machine direction tensile stress-strain graph of a flexible multilayer film according to one or more embodiments of the present disclosure. [0021] FIG. 9 is a transverse direction tensile stress-strain graph of a t-peel seal formed from flexible multilayer films according to one or more embodiments of the present disclosure.

[0022] The embodiments set forth in the drawings are illustrative in nature and not intended to be limiting to the claims. Moreover, individual features of the drawings will be more fully apparent and understood in view of the detailed description.

DETAILED DESCRIPTION

[0023] A flexible container in accordance with the present disclosure includes a package body formed from at least one flexible panel shaped with a plurality of seals. Such a flexible panel and plurality of seals form an enclosed interior of the flexible container. The flexible panel, of which there is at least one in the pouch or bag construction, is formed from a flexible film. The flexible film may comprise a sealant layer and a substrate layer as separate distinct layers in the form of a multilayer film or may comprise a single layer forming both the sealant layer and the substrate layer. The substrate layer comprises a microchannel film comprising a matrix comprising a thermoplastic material comprising a polyolefin and a plurality of channels disposed in parallel in the matrix and extending from a first end to a second end of the microchannel film. At least one of the plurality of seals is a spine seal disposed along an axial length of the flexible container. Further, the flexible film is oriented such that the channels are aligned with the spine seal in the formed flexible container.

[0024] For purposed of this disclosure, the term“spine seal” refers to a seal formed along the axial length of a formed flexible container. Spine seals and the proximal film material in flexible containers are generally the location of packaging failure as a result of dropping the packaging and are thus prime candidates for improvement. It will be appreciated that spine seals may be a lap-seal or may be a t-peel seal. As known to those skilled in the art, a“lap-seal” is a seal type where the two layers of material to be sealed are simply overlapped and exterior of the film is sealed onto the interior of the film and a“t-peel seal” (also known as a“fin seal”) is a seal where both interior edges of the film are sealed together.

[0025] The channels in the microchannel film provide orthotropic properties to the flexible film. Specifically, the channels result in the microchannel film having areas of localized thinning where the effective material thickness is reduced by the void formed by the channels.

As such, the microchannel film, and by extension the flexible film, exhibits more flexible in a direction perpendicular to the axis of the channels (“width”) than in a direction aligned to the axis of the channels (“length”). The increased flexibility in the width direction of the microchannel film results because of the reduced force required to stretch the microchannel film at each of the channels as a result of the localized thinning of the effective thickness with the passage of the channels. Specifically, the channels within the microchannel film encourage strain to be relieved through material thinning of the material at each channel and away from the seal area, before the strain has exceeded the strength threshold of the spine seal.

[0026] Assembling the flexible container such that the flexible film is oriented with the channels aligned with the spine seal in the formed flexible container takes advantage of the orthotropic properties of the flexible film. Specifically, the hoop direction of the formed flexible container has the increased spread of flexibility afforded by the plurality of channels. As such, strain introduced into the hoop direction of the flexible container may be relieved across the entire flexible film and not solely concentrated close to the seal. The axial direction - at 90 degrees to the hoop direction - of a flexible container formed from the disclosed flexible multilayer film is largely unaffected.

[0027] Referring to FIGS. 1 and 2, one or more embodiments of a flexible container 1 are shown. The depicted flexible container 1 is rectangular; however, various additional sizes and shapes are contemplated herein and within the scope of this disclosure. As stated above, the flexible container 1 could be a pillow pouch or a stand-up pouch.

[0028] With reference to FIG 1, in one or more embodiments, the flexible panels 10 forming the flexible container 1 include a front wall 12 and a rear wall 14. The front wall 12 has a first end 16 and a second end 18 and the rear wall 14 has a first end 17 and a second end 19. Further, side edges 20 connect the first ends 16, 17 and the second end 18, 19. The rear wall 14 is adhered to the front wall 12 at corresponding first ends 16, 17 to form a first end seal 24. The rear wall 14 is adhered to the front wall 12 at corresponding second ends 18, 19 to form a second end seal 28. Additionally, the rear wall 14 is adhered to the front wall 12 at corresponding side edges 20 to form spine seals 26.

[0029] With reference to FIG 2, in one or more embodiments, the flexible panels 10 forming the flexible container 1 include a front wall 12, a rear wall 14, a first side panel 32, and a second side panel 34. The first side panel 32 and the second side panel 34 are laterally opposed in the structure of the flexible container 1. The front wall 12 has a first end 16 and a second end 18, the rear wall 14 has a first end 17 and a second end 19, the first side panel has a first end 16 and a second end 18, the rear wall 14 has a first end 17 and a second end 19, the first side panel 32 has a first end 36 and a second end 38, and the second side panel 34 has a first end 37 and a second end 39. Further, side edges 20 connect the first ends 16, 17, 36, 37 and the second end 18, 19, 38, 39. The front wall 12 and the rear wall 14 are adhered to the first side panel 32 and the second side panel 34 at corresponding first ends 16, 17, 36, 37 to form a first end seal 24.

The front wall 12 and the rear wall 14 are adhered to the first side panel 32 and the second side panel 34 at corresponding second ends 18, 19, 38, 39 to form a second end seal 28. Additionally, the rear wall 14 and the front wall 12 are adhered to the first side panel 32 and the second side panel 34 at corresponding side edges 20 to form a plurality of spine seals 26. In one or more embodiments, the rear wall 14, the front wall 12, the first side panel 32, and the second side panel 34 may form a seal around a pouring spout 60.

[0030] The flexible panels 10 forming the flexible container 1 may be formed from a flexible film. The flexible film may be a multilayer film which includes a sealant layer and a substrate layer as distinct layers. The flexible film may also be provided as a single layer film with the sealant layer sand the substrate layer formed from a single layer of homogenous formulation.

The sealant layer is configured to form a heat sealable seal upon application of heat and optionally pressure. The substrate layer is a flexible film configured to provide the structural aspects of the flexible container 1. Specifically, the flexible film comprises the sealant layer to form a seal with adjoining media and the substrate layer to provide desired structural, environmental, or other material properties.

[0031] As heat sealable seals, the first end seal 24, the second end seal 28, and the spine seals 26 are generally formed by applying heat to the flexible film. Application of the heat causes heat to transfer through the flexible film and melt and fuse the sealant layer to form a seal. In one or more embodiments, while the sealant layer is melted to form a seal, the substrate layer or layers does not melt. Subsequently, the flexible film is cooled to room temperature and the sealant layer solidifies to form the completed seal. It will be appreciated that the sealant layer may be activated by any form of heat induction in processes such as conductive sealing, high frequency (HF) sealing, radio frequency (RF) sealing, ultrasonic (US) sealing, inductive sealing, hot air sealing, or flame sealing techniques. [0032] In one or more embodiments, the first end seal 24, the second end seal 28, and the spine seals 26 may hermetically seal the interior volume of the flexible container 1.

[0033] The adhesion strength may be adjusted by adjusting the temperature, pressure, or dwell time of the sealing bar configured to form the seals in the desired locations. For example, increasing the pressure applied by the sealing bar during a sealing operation generally results in a seal with an increased adhesion strength. Similarly, increasing the temperature of the fusing nip also generally results in an increased adhesion strength until such an elevated temperature is reached that the integrity of the film structure is damaged. For example, a lock-up (or non- peelable) seal may be expected to form with a fusing nip pressure of 5 bars (0.5 N/mm²) and a temperature in excess of 130 °C for ½ a second. The particular materials and structure of the films determine the specific seal strength profile for varying temperatures and/or pressures. Besides temperature and pressure, the sealing bar geometry may influence seal strength.

[0034] As indicated, the flexible film comprises a microchannel film 80. With reference to FIGS. 3-6, the microchannel film 80 is formed from the matrix 88 comprising a thermoplastic material and a plurality of channels 90 disposed in parallel in the matrix 88. The term“parallel” as used herein means extending in the same direction and never intersecting.

[0035] The microchannel film 80 has a first film end 84 and a second film end 86. The plurality of channels 90 are disposed in parallel in the matrix 88 from the first film end 84 to the second film end 86. In one or more embodiments, the plurality of channels 90 are spaced at least 633pm apart from each other as measured from the centers of adjacent channels. In various further embodiments, the plurality of channels 90 are spaced at least 750 pm apart from each other, at least 1000 pm apart from each other, at least 1250 pm apart from each other, or at least 1500 pm apart from each other. It will further be appreciated that in various embodiments the spacing of the plurality of channels 90 may be consistent across the microchannel film 80 or varied across the microchannel film 80 depending on the desired properties in the transverse direction (TD). The transverse direction is the direction at right angle to the machine direction of the film web as it moves through the film-making machine.

[0036] In one or more embodiments, the spacing of the channels 90 is consistent across the entire width of the microchannel film 80. A consistent spacing of the channels 90 provides a uniform expansion in the hoop direction of the flexible container as well as uniform absorption of applied stress through stretching of the flexible multilayer film at the channels 90.

[0037] In various embodiments, the spacing of the channels 90 may vary across the width of the microchannel film 80. For example, the channels 90 may be positioned at smaller intervals in areas of the flexible panels 10 positioned proximal the spine seal 26 and at larger intervals in areas of the flexible panels 10 positioned distal from the spine seal 26. Conversely, the channels 90 may be positioned at larger intervals in areas of the flexible panels 10 positioned proximal the spine seal 26 and at smaller intervals in areas of the flexible panels 10 positioned distal from the spine seal 26. Varying the spacing of the channels 90 allows the properties of the flexible container 1 to be tuned to match the expected areas where increased strength is desired while allow for increased stretch in areas where acceptable.

[0038] In one or more embodiments, the plurality of channels 90 can be at least partially filled with a gas, for example, air or an inert gas. In further embodiments, the plurality of channels 90 can be at least partially filled with a second thermoplastic material with distinct properties than the thermoplastic material forming the matrix 88.

[0039] In one or more embodiments, the channels 90 of the microchannel film 80 are provided across the entire multilayer film of the at least one flexible panel 10. The

microchannel film 80 comprising channels 90 spanning the entire width of the flexible panels 10 allows the entirety of the flexible container 1 to stretch in the hoop direction to absorb and dissipate forces in the hoop direction of the flexible container 1.

[0040] In one or more embodiments, the plurality of channels 90 within the microchannel film 80 may have an aspect ratio in the range of from 1 :1 to 100:1 forming circular or elliptical profiles; for example, in the range of from 10:1 to 100:1; or in the alternative, in the range of from 1 : 1 to 50: 1 ; or in the alternative, in the range of from 10:1 to 50: 1. The aspect ratio is measured as the ratio of longest to shortest dimensions of a channel’s 90 cross-section perpendicular to the machine direction (MD) of the microchannel film 80.

[0041] In one or more embodiments, the microchannel film 80 may comprise at least 10 percent by volume of the matrix 88, based on the total volume of the microchannel film 80; for example, the microchannel film 80 may comprise from 90 to 33 percent by volume of the matrix 88, based on the total volume of the microchannel film 80; or in the alternative, from 80 to 33 percent by volume of the matrix 88, based on the total volume of the microchannel film 80; or in the alternative, from 80 to 50 percent by volume of the matrix 88, based on the total volume of the microchannel film 80; or in the alternative, from 80 to 60 percent by volume of the matrix 88, based on the total volume of the microchannel film 80.

[0042] In one or more embodiments, the microchannel film 80 may comprise from 10 to 66 percent by volume of voidage 82, based on the total volume of the microchannel film 80; for example, the microchannel film 80 may comprise from 20 to 66 percent by volume of voidage 82, based on the total volume of the microchannel film 80; or in the alternative, from 20 to 50 percent by volume of voidage 82, based on the total volume of the microchannel film 80; or in the alternative, from 20 to 40percent by volume of voidage 82, based on the total volume of the microchannel film 80. It will be appreciated that the thickness of the film and the expected loading of the film may effect that maximum acceptable volume of voidage while manitianing sufficient flexible film integrity to resist failure. In one or more embodiments, the plurality of channels 90 each have a diameter (the long axis of a cross-section), of at least 1 pm; for example, from 1 pm to 2000 pm; or in the alternative, from 5 to 1200 pm; or in the alternative, from 25 to 600 pm; or in the alternative, from 40 to 400 pm. It will be appreciated that with a total film thickness of approximatly 100 to 50 pm, the channels 90 may have a minor width (the short axis of a cross-section) of apporxiamtly 25 to 40 pm indepdnent of the diameter of the channels 90. The channels 90 may have a cross-sectional shape selected from the group consisting of circular, rectangular, oval, diamond, triangular, square, curvilinear, and

combinations thereof.

[0043] In one or more embodiments, the plurality of channels 90 may include one or more seals at the first film end 14, the second film end 16, therebetween the first film end 14 and the second film end 16, and/or combinations thereof. In further embodiments, the channels 90 are continuous between the first film end 14 and the second film end 16.

[0044] The matrix 88 of the microchannel film 80 comprises a thermoplastic material formed from a polyolefin. In various embodiments, the polyolefin is selected from high density polyethylene (HDPE); heterogeneously branched linear low density polyethylene (LLDPE); heterogeneously branched ultra low linear density polyethylene (ULDPE); homogeneously branched, linear ethylene/alpha-olefm copolymers; homogeneously branched, substantially linear ethylene/alpha-olefm polymers; high pressure, free radical polymerized ethylene polymers and copolymers; and polypropylene. The selection of the thermoplastic material should provide sufficient melt strength such that during fabrication of such microchannel films 80 the channels 90 maintain structural integrity to prevent the collapse of the channels 90. It will be appreciated that the channels 90 of the microchannel film 80 may be collapsed in the region of the plurality of seals during formation of the flexible container, especially in embodiments where the flexible film is a single layer forming both the substrate layer and the sealant layer.

[0045] Exemplary polyethylene suitable for the microchannel films 80 can have a melt flow rate in the range of from 0.1 to 500 g/10 minutes (measured at 190° C and 2.16 Kg); or in the alternative from 5 to 30 g/10 minutes; or in the alternative, from 1 to 15 g/10 minutes; or in the alternative, from 1 to 10 g/10 minutes; or in the alternative, from 2 to 7 g/10 minutes.

[0046] Exemplary polypropylene suitable for the microchannel films 80 can have a melt flow rate in the range of from 0.1 to 500 g/10 minutes (measured at 230° C an d 2.16 Kg), or in the alternative from 2 to 60 g/10 minutes; or in the alternative from 2 to 30 g/10 minutes; or in the alternative from 2 to 20 g/10 minutes; or in the alternative from 5 to 15 g/10 minutes.

[0047] In various embodiments where the flexible film is a multilayer film, the substrate layer may be a monolayer or may be formed of a plurality of layers to impute desired physical and chemical properties to the flexible film. For example, the substrate layer may provide oxygen barrier properties, opacity, or other desirable material properties to the flexible film based on the formulation of the substrate layer.

[0048] In one or more embodiments where the flexible film is a multilayer film, the sealant layer of the flexible film may include any sealant formulation known to those skilled in the art as utilized in the formation of flexible packaging seals. For example a blend of a propylene based plastomer or elastomer, and at least one of a polyethylene or a polystyrene based polymer may be utilized in one or more embodiments.

[0049] It will be appreciated that the flexible film utilized in each of the at least one of flexible panels 10 may differ. Specifically, the flexible panel 10 forming one face of the flexible container 1 may be formed from a flexible film selected for different physical properties than the flexible panel 10 forming a second face of the flexible container 1. For example, the flexible panel forming a front face of the flexible container 1 and an integrated pouring spout may be formed from a different flexible film than the flexible panel forming a back face of the flexible container 1 which does not include a pouring spout.

[0050] The thickness or gauge of the flexible film may vary based on the desired film properties. In embodiments where the flexible film is a multilayer filme, the total thickness of the flexible film is determined by the sum of the thickness or gauge of the sealant layer and the thickness or gauge of the substrate layer. In various embodiments, the sealant layer may comprise a thickness of 10 to 30 microns, 15 to 20 microns, 18 to 22 microns, or approximately 20 micronsln various embodiments, the substrate layer may comprise a thickness of 20 to 170 microns, 30 to 120 microns, or 40 to 100 microns. It will be appreciated that in various embodiments, the total thickness of gauge of the flexible film may be 60 to 200 microns, 70 to 180 microns, 80 to 160 microns, or 100 to 150 microns.

[0051] It should be understood that the flexible film may contain various additives.

Examples of such additives include antioxidants, ultraviolet light stabilizers, thermal stabilizers, slip agents, antiblock pigments or colorants, processing aids (such as fluoropolymers), crosslinking catalyst, flame retardants, fillers, foaming agents, and combinations thereof.

[0052] In one or more embodiments with a multilayer film, the substrate layer comprises the microchannel film 80 layer proximal the sealant layer and a polyethylene terephthalate (PET) surface layer distal the sealant layer. The PET surface layer provides a smooth exterior surface to the flexible container 1 for both cosmetic and practical purposes such as easing placement of indicia in the form of printing on the flexible container 1. It will be appreciated that PET is provided as an exemplary surface layer, but other formulations of the surface layer may be utilized.

[0053] Lamination of additional material layers to the microchannel film 80, naturally results in less flexibility in the resulting flexible film. Specificially, the additional layers, such as a PET surface layer, may impede stretching of the channels 90 in the hoop direction. However, utilization of additional material layers to provide desired film properties may be included when consideration is made toward retaining an acceptable force necessary to initiate strentching of the channels 90 in the hoop direction. It will be appreciated that the exact acceptable force may vary depending on the strength of the seals forming the flexible package as well as the overall film strength and integrity. [0054] In one or more embodiments, the flexible container 1 comprises indicia. Non-limiting examples of the indicia include printing to indicate the contents of the flexible container 1, instructions for opening the flexible container 1, and marketing slogans and graphics.

[0055] It will be appreciated that any existing heat-sealed polymeric container design may have increased effective hoop strength by implementing the techniques and film layout of the present disclosure. Specifically, in the method includes forming the existing polymeric container which has at least one spine seal along an axial length of the container from the flexible film as disclosed in the present disclosure. The flexible film including a microchannel film having (a) a matrix comprising a thermoplastic comprising a polyolefin, and (b) at least one or more channels disposed in parallel in said matrix from a first end to a second end of said microchannel film. The microchannel film comprises from 10 to 90 percent by volume of voidage, based on the total volume of the microchannel film. When orienting the flexible multilayer film for formation of the polymeric container, the flexible film is oriented such that the channels are aligned with the spine seal.

[0056] EXAMPLES

[0057] Samples of a flexible film with channels were tested to demonstrate the behavior and performance of the flexible film in isolation from variables introduced by a seal. Specifically, samples of 100 micron film formed from Elite 5100, a linear low density polyethylene resin commercially available from Dow Chemical Company (Midland, MI), were prepared as Example 1. The channels in the Example 1 film were spaced at nominally 60 microns, had a nominal diameter of 30 micron microns, and were filled with ambient air. Duplicate samples of Example 1 were prepared for repeat tensile testing of the Example 1 film in both the transverse direction and the machine direction.

[0058] In a first test, Example 1 flexible film samples were subjected to tensile testing in the transverse direction. Specifically, Example 1 was tested in the direction representative of the hoop direction in a completed flexible container with the channels aligned with the spine seal. Tensile testing was completed in accordance with ISO 527/3 using strips 15 millimeters (mm) by 170 mm at a pull speed of 500 millimeters per minute (mm/min) with a grip distance of 100 mm. The resulting stress-strain curves for the tested Example 1 samples are provided as FIG. 7. It may be perceived in FIG. 7 that a series of small unstable triggers represent the cycle of stretching and stiffening of the flexible film as the channels relieved stress in the flexible film through stretching.

[0059] In a second test, the Example 1 flexible film samples were subjected to tensile testing in the machine direction. Specifically, Example 1 was tested in the direction representative of the axial direction in a completed flexible container and along the axial length of the channels. Tensile testing was completed in accordance with ISO 527/3 using strips 15 millimeters (mm) by 170 mm at a pull speed of 500 millimeters per minute (mm/min) with a grip distance of 100 mm. The resulting stress-strain curves for the tested Example 1 samples are provided as FIG. 8. It may be observed in FIG. 8 that the series of small unstable triggers represent the cycle of stretching and stiffening of the flexible film present in FIG. 7 are absent. As such, it is demonstrated that the properties in the axial direction are not severely-adjusted by instabilities in the flexible multilayer film introduced with the channels leaving the axial properties minimally affected.

[0060] Testing was also completed on the behavior of seals and flexible multilayer film in combination. Seal integrity testing is measured in a laboratory method with a tensile test of a sealed strip to determine the force until breakage. Finite element analysis may also be used to model behavior of the seal and associated films. Such testing also allows for determination regarding if the seal itself fails or if the surrounding film fails with the seal proper remaining intact.

[0061] Finite element analysis of a t-peel spine seal formed from films having no channels was initially completed to provide a baseline and comparative behavior. The finite element analysis demonstrated that the seal proper remains intact with the film surrounding the seal experiencing failure.

[0062] Test samples of sealed flexible films were prepared in accordance with the present disclosure. Specifically, samples of Example 1 were sealed together with a t-peel seal where the flexible film was oriented such that the channels were aligned with the seal. The flexible film was a single layer film with the single layer serving as both the substrate layer and the sealant layer. The sealing parameters were 130 degrees for 0.5 seconds at 0.5 N/mm². The prepared samples were designated Example 2 for seal integrity testing. Tensile testing was completed in accordance with ISO 527/3 at a pull speed of 500 millimeters per minute (mm/min) with a grip distance of 100 mm with the pull force along the transverse direction of the film representative of the hoop direction in a flexible container in accordance with the present disclosure. The resulting stress-strain curves for the tested Example 2 samples are provided as FIG. 9. It may be observed in FIG. 9 that the series of small unstable triggers representing the cycle of stretching and stiffening of the flexible film as the channels relieved stress in the flexible film through stretching observed in FIG. 7 are also present. As such, it may be determined that spine seals prepared in conformity with the present disclosure will demonstrate triggering of the local yield around each channel in the film and then, only once all channels have yielded locally, exhibit whole sample failure. Substantial elongation in the hoop direction of the flexible multilayer film forming the presently disclosed flexible containers may be experienced, such as in the case of the flexible container being dropped, before failure of the seal and/or film forming the flexible container.

[0063] It is noted that the tensile testing of Example 2, as illustrated in FIG. 9, determined the eventual position of failure of the tested samples was not directly at the sealed area. This experience is in contravention to the failure mechanism demonstrated with the finite element analysis of test samples without channels where failure occurred in the region of the seal. As such, it is demonstrated that the attributes and layout of the microchannel film utilized in the flexible container of the present disclosure shift and dissipate the forces experienced during a drop test of the flexible container when the spine seal is stressed.

[0064] It will be appreciated that the microchannel film spreading the stress of a drop impact across a larger portion of the flexible container films allows for reduction in overall package thickness. Specifically, since most of the packaging perimeter is not a seal, in traditional packaging schemes most the packaging is underutilized or overdesigned as the selected film thickness must be able to withstand the concentrated stress near the seal. By shifting the severity of the experienced stress concentration away from the seal with the stress reduction capabilities of the plurality of channels in the microchannel film, the packaging material is better utilized and may allow for thinning down of the gauge of the entire package. Thinning the packaging material gauge provides cost advantages as less raw material is used in each flexible package.

[0065] It is noted that there is an inherent degree of uncertainty that may be attributed to any quantitative comparison, value, measurement, or other representation. Further it is understood that there is a degree by which a quantitative representation may vary from a stated reference without resulting in a change in the basic function of the subject matter at issue. For conciseness, the terms“about”,“substantially” and the like are omit from disclosed values, measurements, or other representations, but are implicitly include within the intended meaning and scope to cover these stated situations.

[0066] The singular forms“a”,“an” and“the” include plural referents, unless the context clearly dictates otherwise.

[0067] It is further noted that terms like“preferably,” "generally,"“commonly,” and “typically” are not utilized herein to limit the scope of the claimed invention or to imply that certain features are critical, essential, or even important to the structure or function of the claimed invention. Rather, these terms are merely intended to highlight alternative or additional features that may or may not be utilized in a particular embodiment of the present disclosure.

[0068] Throughout this disclosure ranges are provided. It is envisioned that each discrete value encompassed by the ranges are also included. Additionally, the ranges which may be formed by each discrete value encompassed by the explicitly disclosed ranges are equally envisioned.

[0069] As used in this disclosure and in the appended claims, the words“comprise,”“has,” and“include” and all grammatical variations thereof are each intended to have an open, non limiting meaning that does not exclude additional elements or steps.

[0070] While particular embodiments have been illustrated and described herein, it should be understood that various other changes and modifications may be made without departing from the spirit and scope of the claimed subject matter. Moreover, although various aspects of the claimed subject matter have been described herein, such aspects need not be utilized in combination. It is therefore intended that the appended claims cover all such changes and modifications that are within the scope of the claimed subject matter.

Claims

1. A flexible container comprising:

a package body formed from at least one flexible panel shaped with a plurality of seals, thereby enclosing an interior of the container,

wherein the at least one flexible panel is formed from a flexible film,

wherein the flexible film comprises a microchannel film, the microchannel film comprising:

(a) a matrix comprising a thermoplastic material comprising a polyolefin, and

(b) a plurality of channels disposed in parallel in said matrix from a first end to a second end of said microchannel film;

wherein at least one of the plurality of seals is a spine seal disposed along an axial length of the container; and

wherein the flexible film is oriented such that the channels are aligned with the spine seal.

2. The flexible container of claim 1, wherein the flexible panels comprise a front wall and a rear wall, the front wall and the rear wall each comprising a first end, a second end, and side edges connecting the first end and the second end,

wherein the rear wall is adhered to the front wall at corresponding first ends to form a first end seal, the rear wall is adhered to the front wall at corresponding second ends to form a second end seal, and the rear wall is adhered to the front wall at corresponding side edges to form the spine seals.

3. The flexible container of claim 1, wherein the flexible panels comprise a front wall, a rear wall, and laterally opposite first and second side panels,

wherein the front wall, the rear wall, the first side panel, and the second side panel each comprise a first end, a second end, and side edges connecting the first end and the second end, wherein the rear wall and front wall are adhered to the first and second side panels at corresponding first ends to form a first end seal, the rear wall and front wall are adhered to the first and second side panels at corresponding second ends to form a second end seal, and the rear wall and front wall are adhered to the first and second side panels at corresponding side edges to form a plurality of the spine seals.

4. The flexible container of any of claims 1 through 3, wherein the channels of the microchannel film are provided across the entire flexible film.

5. The flexible container of any of claims 1 through 4, wherein the flexible film is a multilayer film comprising a sealant layer and a substrate layer.

6. The flexible container of claim 5, wherein the substrate layer comprises the

microchannel film layer proximal the sealant layer and a PET surface layer distal the sealant layer.

7. The flexible container of claim 1, wherein the sealant layer comprises a blend of a propylene based plastomer or elastomer, and at least one of a polyethylene or a polystyrene based polymer.

8. The flexible container of any of claims 1 through 7, wherein the spine seal is a lap-seal.

9. The flexible container of any of claims 1 through 7, wherein the spine seal is a t-peel seal.

10. The flexible container of any of claims 1 through 9, wherein said plurality channels are spaced at least 633 pm apart from each other as measured from the center of adjacent channels.

11. The flexible container of any of claims 1 through 10, wherein each said plurality of channels have a diameter of at least 1 pm.

12. The flexible container of any of claims 1 through 11, wherein said microchannel film comprises from 10 to 66 percent by volume of voidage, based on the total volume of the microchannel film

13. The flexible container of claim 12, wherein one or more gases are disposed in said one or more channels thereby forming channels with the volume of voidage filled with said one or more gases.

14. The flexible container of any of claims 1 through 13, wherein the polyolefin is selected from high density polyethylene (HDPE); heterogeneously branched linear low density polyethylene (LLDPE); heterogeneously branched ultra low linear density polyethylene (ULDPE); homogeneously branched, linear ethylene/alpha-olefm copolymers; homogeneously branched, substantially linear ethylene/alpha-olefm polymers; high pressure, free radical polymerized ethylene polymers and copolymers; and polypropylene.

15. A method of increasing effective hoop strength in a heat-sealed polymeric container, the method comprising:

forming the polymeric container from a flexible film comprising a microchannel film, the microchannel film comprising:

(a) a matrix comprising a thermoplastic comprising a polyolefin, and

(b) at least one or more channels disposed in parallel in said matrix from a first end to a second end of said microchannel film, wherein said microchannel film comprise from 10 to 90 percent by volume of voidage, based on the total volume of the microchannel film;

wherein the heat-sealed polymeric container if formed with at least one spine seal along an axial length of the container; and