Heat sealing systems and methods, and related articles and materials

A bag may be formed from a tube of high strength packaging material by forming a heat seal in the end of the tube. As part of forming the heat seal, one or more supplying apparatuses, which may be air outlets, are positioned for being in opposing face-to-face relation with, and for causing heat transfer with, at least one outer portion of the tube while a transportation system transports the tube to a nipping apparatus.

OTHER RELATED APPLICATIONS

Two U.S. patent applications that are both entitled HIGH STRENGTH PACKAGES AND PACKAGING MATERIALS, are both being filed on the same day as the present application, and are identified by Ser. Nos. 12/776,483 and 12/776,494, respectively, are both incorporated herein by reference in their entirety.

TECHNICAL FIELD

This disclosure relates to heat sealing systems and methods and, more particularly, to using heat to close an end of a tube to form a bag.

BACKGROUND OF THIS DISCLOSURE

It is well known to form bags from tubes, by closing ends of the tubes. Sometimes a tube is formed from a heat sealable material, and heat is used to form a seal that closes an end of the tube. As a contrasting example, sometimes the end of a tube is sewn closed to form a bag, such as when the tube is constructed of a material that is not heat sealable, or in other circumstances in which a suitable heat seal may not be formed (e.g., in tubes constructed of high strength packaging material). In some situations, a heat seal is considered superior to a sewn seal. Accordingly, it is desirable to provide improvements that promote the usage of heat seals (e.g., in some tubes constructed of high strength packaging material).

SUMMARY OF SOME ASPECTS OF THIS DISCLOSURE

One aspect of this disclosure is the provision of improvements to a system for sealing a tube to form a bag. A tube typically has opposite first and second sides that each extend between opposite ends of the tube. The opposite ends of the tubes may be “straight cut” (e.g., at least substantially straight cut (i.e., not step cut)). The first side of the tube includes a first outer portion of the tube and a second outer portion of the tube, and the second side of the tube includes a third outer portion of the tube and a fourth outer portion of the tube. The tube may be at least partially constructed of a woven polymer material.

In accordance with one aspect, the system includes a transportation system for transporting the tube in a downstream direction along a path. A folding apparatus is positioned along the path for moving the first and third outer portions of the tube relative to the second and fourth outer portions of the tube and, thereby, folding the tube into a folded-over configuration while the transportation system transports the tube proximate the folding apparatus. In the folded-over configuration, the first and second outer portions of the tube are facing substantially toward one another, and the third and fourth outer portions of the tube are facing substantially away from one another. A supplying apparatus (e.g., air outlet) is positioned along the path for being in opposing face-to-face relation with, and for causing heat transfer with, at least one outer portion of the tube while the transportation system transports the tube proximate the supplying apparatus. The at least one outer portion of the tube is selected from the group consisting of the second outer portion of the tube, the third outer portion of the tube, and the fourth outer portion of the tube. A nipping apparatus is positioned downstream from both the folding apparatus and the supplying apparatus along the path, for receiving the at least partially heated tube in the folded-over configuration from the transportation system. The nipping apparatus is for nipping at least the first, second, third and fourth outer portions of the tube while the tube is in the folded-over configuration. The nipping typically completes the folding and the forming of the seal(s).

In accordance with one aspect, the supplying apparatus comprises an air outlet mounted for being in opposing face-to-face relation with the at least one outer portion of the tube while the transportation system transports the tube proximate the air outlet. The air outlet is for discharging air onto the at least one outer portion of the tube while the transportation system transports the tube proximate the air outlet, so that forced convection causes heat transfer with the at least one outer portion of the tube.

In accordance with one aspect of this disclosure, a system for sealing a tube includes a transportation system for transporting the tube in a downstream direction along a path. A first supplying apparatus (e.g., air outlet) is positioned along the path for being in opposing face-to-face relation with, and for causing heat transfer with, a first outer portion of the tube while the transportation system transports the tube proximate the first supplying apparatus. A second supplying apparatus (e.g., air outlet) is positioned along the path for being in opposing face-to-face relation with, and for causing heat transfer with, a second outer portion of the tube while the transportation system transports the tube proximate the second supplying apparatus. The first and second supplying apparatuses are opposite from one another, and the first and second outer portions of the tube are opposite from one another. A nipping apparatus is positioned downstream from both the first and second supplying apparatuses, for receiving the tube from the transportation system and completing the folding and the forming of the seal(s).

Other aspects and advantages of the present disclosure will become apparent from the following.

DETAILED DESCRIPTION

Referring now in greater detail to the drawings, in which like numerals refer to like parts throughout the several views, a sealing system20is disclosed in the following, in accordance with a first embodiment of this disclosure. In accordance with the first embodiment, the sealing system20may be like conventional closers systems that are available as Model 90-I and Model 92-I from Stonepak by Premier Tech Systems, of Salt Lake City, Utah, except for variations noted in this disclosure and variations that will be apparent to one of ordinary skill in the art.

In the following, initially the sealing system20is discussed primarily with reference toFIGS. 1-6, only with very general reference to a tube22(FIGS. 7-14) that is to have its upper end sealed closed by the sealing system20to form a bag112(FIGS. 16-18). Then, a method of the sealing system20processing the tube22is discussed very generally and briefly with reference toFIGS. 7-10. Then, the tube22with its ends unsealed is discussed in greater detail with reference toFIGS. 11-14. Then, material from which the tube may be constructed is discussed with reference toFIG. 15. Then, the bag112constructed from the tube22by the sealing system20is discussed with reference toFIGS. 16-18. Then, other embodiments and variations are discussed with reference to the remaining figures.

Referring toFIG. 1, the sealing system20includes a conventional frame. The frame has upright supports (not shown) that support an upper subframe24at a position that is elevated above a floor (not shown) or other suitable surface. The frame includes other frame components that support a wide variety of mounting brackets and other components of the sealing system20.

The tube22(FIGS. 7-14) that is to have its upper end sealed closed by the sealing system20is introduced into an upstream end of the sealing system (i.e., the right-hand end inFIG. 1). The resulting bag112(FIGS. 16-18) with a sealed closed upper end exits a downstream end of the sealing system20(i.e., the left-hand end inFIG. 1). That is, the tube22/bag112travels along a path in a downstream direction through the sealing system20, and the downstream direction extends along the length of the sealing system20. Accordingly and to provide a frame of reference for ease of understanding, throughout this Detailed Description section of this disclosure, the directional references to “upstream” and “downstream” are defined by/relate to the direction in which the tube22/bag112travels through/along the length of the sealing system20.

Referring toFIGS. 1 and 2, the sealing system20includes a transportation system comprising a conventional transport conveyor26that is not novel per se. The transport conveyor26extends between the upstream and downstream ends of the sealing system20, although the transport conveyor may not extend for the entire length of the sealing system. The tube22is introduced to the transport conveyor26at the upstream end, and the transport conveyor carries the tube/bag through the sealing system20, and discharges the bag from the downstream end of the sealing system.

As best understood with reference toFIG. 2, the transport conveyor26includes a rearward pulley system28bthat is positioned behind a forward pulley system28a. Each of the transport conveyor's pulley systems28a,28bincludes an endless belt30that extends around an upstream pulley32and a downstream pulley34, and there may be intermediate pulleys (not shown) in the pulley system. The upstream and downstream pulleys32,34are supported by shafts that hang down from the upper subframe24.

The transport system may be configured differently. For example, the transport system may include multiple transport conveyors, or the like, arranged end to end. As a more specific example, the transport conveyor26may not extend all the way to the downstream end of the sealing system (e.g., the folded tube22(FIGS. 7-9) may be passed from a downstream end of a shorter transport conveyor to another conveyor (e.g., a nip conveyor/nipping apparatus76) that may be characterized as being part of the transport system).

Referring toFIGS. 1 and 2, the sealing system20includes a conventional upstream guide that comprises a pair of adjacent guide rollers36and is not novel per se. The guide rollers36are supported by shafts hanging down from the upper subframe24. The upstream guide/guide rollers36are for guiding an upper portion of the tube22, which is being transported by the transport conveyor, into an upstream end of a guide channel38(FIGS. 3 and 4) defined between forward and rearward guide rails40a,40b. The guide rollers36may be driven, such that the guide rollers may be characterized as being part of the sealing system's transportation system (which also includes the transport conveyor26).

The guide channel38is upwardly and downwardly open. Referring toFIGS. 1-4, the upper opening of the guide channel38may be covered and somewhat obstructed by a cover assembly42that is mounted to the frame of the sealing system20. The cover assembly42may, optionally, be mounted by hinges44(FIG. 3), so that the cover assembly may be pivoted between a closed configuration (FIGS. 1-3) and an open configuration (e.g., see the partially open configuration shown inFIG. 4). More specifically, the closed cover assembly42covers (e.g., obstructs, typically without fully closing) the upper opening of the guide channel38.

The cover assembly42comprises a substantially rigid cover plate43that is pivotably mounted by the hinge assemblies44and carries other components of the cover assembly42. The cover assembly42includes a folding apparatus, which includes upstream and downstream diverters46,47, for folding the tube22into a folded-over configuration while the transport conveyor26transports the tube proximate (e.g., by, past, or the like) the folding apparatus. The lower surface of the cover plate43may optionally also be characterized as being part of the folding apparatus since it may play some role in the folding of the tube22(e.g., such as by not allowing the partially folded tube to unfold due to any resiliency of the tube).

More specifically, the cover assembly42includes a conventional, concavely curved upstream diverter46that is not novel per se. The upstream diverter46is mounted to and/or defined by the upstream end of the cover plate43, for pivoting with the cover plate43. The upstream diverter46is for initiating a folding over of the upper marginal portion of the tube22. The upstream diverter46typically folds the upper marginal portion of the tube22downwardly about ninety degrees relative to the lower portion of the tube, so that the upper marginal portion of the tube extends approximately perpendicularly relative to the lower portion of the tube. For example, the upstream diverter46may be defined by a concavely cut upstream end of the cover plate43, and/or the upstream diverter may include any suitable structure or material that is mounted to the upstream end of the cover plate43for aiding in the folding of the upper marginal portion of the tube.

It is conventional to include a folding apparatus downstream from the upstream diverter46for substantially completing the folding over of the upper portion of the tube22. In this regard, a curved downstream diverter47is mounted to and/or defined by the downstream end of the cover plate43, for pivoting with the cover plate43. The downstream diverter47is shaped (e.g., contoured) for substantially completing the folding over of the upper portion of the tube22, as will be discussed in greater detail below. More specifically, the downstream diverter47typically folds what was originally the upper marginal portion of the tube22about an additional ninety degrees downward relative to the lower portion of the tube.

The cover assembly42further includes an upper heat supplying apparatus (e.g., upper air outlet48a(FIG. 4)) that may be any suitable apparatus (e.g., an infrared radiant heater) for causing heat transfer with at least one outer portion of the tube22while the transport conveyor26transports the tube proximate (e.g., by, past, or the like) the upper heat supplying apparatus. More specifically, the upper heat supplying apparatus is an upper air outlet48athat is in the form of a plate that defines a wall of an upper plenum50a(FIGS. 3 and 4) and has numerous holes (e.g., discharge ports) extending therethrough for discharging air from the upper plenum. The upper air outlet48aextends along a portion of the length of the sealing system20. The upper air outlet48amay be a perforated plate, an air vent, louvers, an air distributor, or any other suitable structure for discharging a flow of air. Substantially all of the air outlet48ais positioned downstream from the upstream diverter46, although variations are within the scope of this disclosure.

The upper plenum50a, which includes the upper air outlet48a, may be mounted to and/or defined by the cover plate43, such that the upper plenum50apivots with the cover plate43. The upper plenum50ais located at a position between the upstream and downstream ends of the cover plate43. The upper plenum50ais typically completely closed, except for including an inlet opening and the holes of the upper air outlet48a. The holes of the upper air outlet48aare located at a lower face of the upper plenum50a/cover assembly42.

The inlet opening to the upper plenum50amay be located at the upper side or rear side of the upper plenum50a/cover assembly42. Since the cover assembly42is mounted for pivoting, provisions may be made so that the supply duct connected to the inlet opening of the upper plenum50aaccommodates for the pivoting. For example, the supply duct may be flexible, or it may comprise first and second ducts fit one inside the other and between which there can be relative rotation when the cover assembly is pivoted. Alternatively, the supply duct may be removably connected by a removable clamp to the inlet opening of the upper plenum50a. Any suitable connection may be used. The upper plenum50ais one of several plenums of the sealing system20, and the supply of air to the several plenums is discussed below, after all of the plenums are introduced.

As best understood with reference toFIG. 4, a lower heat supplying apparatus (e.g., upstream lower air outlet48band/or downstream lower air outlet48c) is beneath the upper plenum50a/covered by the cover assembly42while the cover assembly is in its closed configuration. The lower heat supplying apparatus may be any suitable apparatus (e.g., an infrared radiant heater) for causing heat transfer with at least one outer portion of the tube22while the transport conveyor26transports the tube proximate (e.g., by, past, or the like) the lower heat supplying apparatus.

More specifically, the lower heat supplying apparatus comprises one or more of the lower air outlets48b,48c, each of which is a plate that defines a wall of a lower plenum50band has numerous holes (e.g., discharge ports) extending therethrough for discharging air from the lower plenum. The lower air outlets48b,48ceach extend along a portion of the length of the sealing system20. The lower air outlets48b,48ceach may be a perforated plate, an air vent, louvers, an air distributor, or any other suitable structure for discharging a flow of air.

The lower plenum50bis fixedly mounted to the frame of the sealing system20, so that the lower plenum is beneath the upper plenum50aand covered by the cover assembly42while the cover assembly42is in its closed configuration. The lower plenum50bincludes a conventional upper section that includes the lower air outlet48band is not novel per se. The lower air outlet48bis an upper face of the upper section of the lower plenum50b, and the lower air outlet48bextends parallel to, and is in opposing face-to-face relation with (e.g., is opposite), the lower face (i.e., the upper air outlet48a) of the upper plenum50a.

The lower plenum50bincludes a lower section that includes the lower air outlet48c. The lower air outlet48cextends obliquely, downwardly from the upper section of the lower plenum50b. The lower plenum50bis typically completely closed, except for including an inlet opening53(FIG. 1), the holes in the air outlets48b,48c, and an outlet opening in communication with a passageway54(e.g., tube) for supplying air to an inlet opening of a downstream plenum50d.

Downstream heat supplying apparatuses (e.g., downstream air outlets48d,48e(FIG. 5)) are covered by the cover assembly42while the cover assembly is in its closed configuration. The downstream heat supplying apparatuses may be any suitable apparatuses (e.g., infrared radiant heaters) for causing heat transfer with at least one outer portion of the tube22while the transport conveyor26transports the tube proximate (e.g., by, past, or the like) the downstream heat supplying apparatuses.

More specifically, the downstream heat supplying apparatuses are the downstream air outlets48d,48e, each of which is a plate that defines a wall of a downstream plenum50dand has numerous holes (e.g., discharge ports) extending therethrough for discharging air from the downstream plenum. The downstream air outlets48d,48eeach may be a perforated plate, an air vent, louvers, an air distributor, or any other suitable structure for discharging a flow of air.

The downstream plenum50dis fixedly mounted to the frame of the sealing system20, so that the downstream plenum is downstream from the upper and lower plenums50a,50b. As schematically shown by dashed lines inFIG. 3, the downstream plenum50dis covered by the downstream diverter47while the cover assembly42is in its closed configuration. The downstream diverter47and/or downstream plenum50dare adapted (e.g., sized and arranged) so that the downstream diverter47fits over the downstream plenum50dwith clearance for allowing the folded tube22to pass between the downstream diverter and the downstream plenum, as will be discussed in greater detail below with reference toFIG. 9.

Referring toFIGS. 4 and 5, the downstream plenum50dis generally (e.g., substantially) triangular shaped in that its opposite upright faces/downstream air outlets48d,48eextend obliquely and divergently with respect to one another and downwardly from an convexly curved upper surface of the downstream plenum. Each of the opposite upright faces/downstream air outlets48d,48eextends along a portion of the length of the sealing system20. In addition and as best understood with reference toFIG. 5, each of the opposite upright faces/downstream air outlets48d,48eextend obliquely and convergently with respect to one another in the downstream direction. As a result, the upstream end of the downstream plenum50dis wider than the downstream end of the downstream plenum. That is, the downstream plenum50dbecomes more narrow in the downstream direction.

The downstream plenum50dis typically completely closed, except for including the holes in the downstream air outlets48d,48eand an inlet opening in communication with the passageway54(e.g., tube) for receiving a flow of air from the lower plenum50b. The downstream plenum50dmay receive its flow of air from any other suitable source.

The downstream plenum50d, and more particularly the downstream air outlet48e, is proximate the downstream portion of the forward guide rail40a. An opening56(FIGS. 4 and 5) is defined in and extends through the downstream portion of the forward guide rail40a, so that the rearward face/air outlet48eof the downstream plenum50dis in opposing face-to-face relation with the opening56. The downstream air outlet48eis configured for discharging air through the opening56, as will be discussed in greater detail below.

The opening56(FIGS. 4 and 5) that extends through the downstream portion of the forward guide rail40ais arranged and sized so that the rearward face/air outlet48eof the downstream plenum50dis in opposing face-to-face relation with a rearward supplying apparatus (e.g., rearward air outlet48f). The rearward supplying apparatus may be any suitable apparatus (e.g., an infrared radiant heater, or simply a fan or another type of conventional air mover) for causing heat transfer with at least one outer portion of the tube22while the transport conveyor26transports the tube proximate (e.g., by, past, or the like) the rearward supplying apparatus. More specifically, the rearward supplying apparatus is for providing a forced flow of cool air and/or air at substantially the same temperature as ambient air, for cooling a portion of the tube22, as will be discussed in greater detail below.

More specifically, the rearward supplying apparatus is the rearward air outlet48f, which is a plate (e.g., a portion of the rearward guide rail40b) that defines a wall of a rearward plenum50fand has numerous holes (e.g., discharge ports) extending therethrough for discharging air from the rearward plenum. The rearward air outlet48fextends along a portion of the length of the sealing system20. The rearward air outlet48fmay be a perforated plate, an air vent, louvers, an air distributor, or any other suitable structure for discharging a flow of air. The opening56in the forward guide rail40ais substantially rectangular and substantially corresponds to the substantially rectangular shape of (e.g., the pattern of discharge ports in) the air outlet48, although different shapes and arrangements are within the scope of this disclosure.

The rearward plenum50fis fixedly mounted to the frame or another component of the sealing system20. For example, the rearward plenum50fmay be mounted to a portion of the rearward guide rail40bas shown inFIG. 5, so that the rearward plenum is downstream from the upper and lower plenums50a,50b. As best understood by contrastingFIGS. 3 and 4, the rearward plenum50fis covered by the downstream diverter47while the cover assembly42is in its closed configuration. The rearward plenum50fis typically completely closed, except for including the holes in the rearward air outlet48fand an inlet opening for receiving a flow of air. The rearward plenum's inlet opening may be located at the rear side of the rearward plenum50f.

Air may be supplied to the plenums50a,50b,50d,50fin any suitable manner for helping to facilitate the desired sealing of the tube22to form (or close) a bag112(FIGS. 16-18). Each of the plenums50a,50b,50d,50fmay be part of a forced air system that is for providing a forced flow of air that may be heated or cooled. Each of the forced air supply systems may be at least generally conventional in nature. For example and in accordance with the first embodiment, a first forced air system includes the upper plenum50a; a second forced air system includes the plenums50b,50d; and a third forced air system includes the rearward plenum50f. Alternatively, the plenums50b,50dmay respectively be part of separate forced air systems, and/or other arrangements of plenums/forced air systems are within the scope of this disclosure. For example, the forced air system comprising the rearward air outlet48fmay alternatively simply be in the form of a fan or another type of conventional air mover that is for supplying a flow of otherwise ambient air (e.g., relatively cool ambient air) for causing cooling heat transfer with the respective outer portion of the tube22while the transport conveyor26transports the tube proximate (e.g., by, past, or the like) the fan or the like.

FIG. 6schematically illustrates a forced air system58that may be representative of each of the forced air systems (which respectively include the plenums50a,50b,50d,50f) of the sealing system20. The forced air system58may include a conventional air handler60having an air inlet62, a heating and/or coiling coil64(e.g., any suitable device for changing the temperature of the flow of air, by adding and/or removing heat (e.g., a refrigeration system and/or heating element(s))), and a motor-operate air mover66(e.g., a motor-driven fan or any other suitable device for moving air).

The air supplied from the air handler60may flow in conventional duct(s)68or any other suitable structure that is optionally equipped with a conventional motor-operated, flow-control damper70or another suitable device. The duct(s)68discharge into one or more plenums50(e.g., the respective one or more of the plenums50a,50b,50d,50f), and the flow of air is discharged from the plenum(s)50by way of one or more air outlets48(e.g., the respective one or more of the air outlets48a-48f). The air outlet48may include one or more holes or other openings for discharging a forced flow of air that is for providing forced convention. For example, the air outlet48may be a perforated plate, an air vent, louvers, an air distributor, or any other suitable structure for discharging a flow of air.

The plenum(s)50may be equipped with one or more temperature sensors72that may be connected to a controller74. The controller74may also connected to the coil64, air mover66and damper70for purposes of control. The forced air system58may include any other suitable components such as, but not limited to, components for filtration. In addition and optionally, the forced air system including the plenum50f(FIG. 5) may omit the coil64, and the coils64in the forced air systems including the plenums50a,50b,50dmay only be for adding heat. A variety of different forced air systems are within the scope of this disclosure (e.g., the types of or usage of the features of the forced air systems may vary, depending upon the types of materials, tubes22and bags being processed by the sealing system20). Features of the controller74may be embodied in any suitable manner, such as in software, firmware and/or hardware modules, for providing control over operation of the sealing system20/components of the sealing system/forced air systems/components of the forced air systems.

Referring primarily toFIGS. 1,2and10, a conventional nipping apparatus76, which is not novel per se, is positioned downstream from the folding apparatus (e.g., the upstream and downstream diverters46,47) and the supplying apparatuses (e.g., the air outlets48a-48f). The nipping apparatus76receives the tube22from the transport conveyor26. Nonetheless, the transport conveyor26extends all the way to the downstream end of the sealing system20, and the transport conveyor26at least partially carries the tube22/bag all the way to the downstream end of the sealing system.

The nipping apparatus76performs a nipping function, but it may also be characterized as being part of the sealing system's transportation system (which also includes the transport conveyor26), since the nipping apparatus may help in carrying the tube22/bag to the downstream end of the sealing system20. Also, and for example, the transport conveyor26may not extend all the way to the downstream end of the sealing system20, such that the nipping apparatus76, or another suitable device, completes the transporting of the tube22to the downstream end of the sealing system.

As best understood with reference toFIGS. 2 and 10, the nipping apparatus76includes a rearward pulley system78bthat is positioned behind a forward pulley system78a. Each of the nipping apparatus' pulley systems78a,78bincludes an endless belt80that extends around an upstream pulley82, intermediate pulleys84, and a respective one of the downstream pulleys34(FIG. 1). The upstream and intermediate pulleys82,84are supported by shafts that hang down from the upper subframe24. The nipping apparatus76may be configured differently. For example, the nipping apparatus76may include multiple nipping conveyors, or the like, arranged end to end.

As best understood with reference toFIG. 1, the sealing system20includes a conventional drive system, which is not novel per se, for driving the respective pulleys of the transport conveyor26and the nipping apparatus76, and the guide rollers36. The drive system includes an electric motor86and a gear box88. A drive chain or belt89, or any other suitable device for transferring rotary power, connects the output shaft of the motor86to the input shaft of the gear box88. The respective pulleys of the transport conveyor26and the nipping apparatus76, and the guide rollers36, are driven in a conventional manner by way of one or more chains or belts90, or any other suitable devices for transferring rotary power. Some of the features of the drive system are hidden from view inFIG. 1and, therefore, they are schematically illustrated by dashed lines. The one or more belts90, or the like, connect the output shaft(s)88aof the gear box88to the respective shafts that hang down from the upper subframe24and support the respective pulleys of the transport conveyor26and the nipping apparatus76, and the guide rollers36. One or more of the pulleys of the transport conveyor26and the nipping apparatus76, and the guide rollers36, may be idler pulleys or rollers that are not directly driven by the sealing system's drive system. Any suitable drive system(s) may be used in the sealing system20.

The sealing system20may be constructed of any suitable materials. In addition, surfaces (e.g., metal surfaces) of the sealing system20that the tube22comes into sliding contact with (e.g., the folding apparatus) may be coated with Teflon brand coating or other suitable materials for reducing friction. The hot air supplied by the sealing system20may also help to reduce the friction associated with the tube22sliding relative to features of the sealing system.

A method of the sealing system20processing the tube22is discussed very generally and briefly in the following with reference toFIGS. 7-10, in accordance with the first embodiment.FIGS. 7 and 8schematically show the flat tube22being conveyed through and folded over by the folding apparatus (e.g., the upstream and downstream diverters46,47).FIG. 9schematically shows the folded-over upper end of the tube22being conveyed between the downstream and rearward plenums50d,50fby the transport conveyor26.FIG. 9is schematic because, for example, some of the clearances shown are exaggerated. For example and in the context of the tube22passing between the downstream diverter47(FIGS. 1-4) and the downstream plenum50d, typically just enough clearance will be provided for the tube to reasonably pass through without any unwanted effects. For example, while the cover assembly42is in its closed configuration, the outer surface of the downstream air outlet48dand the inner surface of the downstream diverter47are in opposing face-to-face configuration with one another, and the clearance between the outer surface of the downstream air outlet48dand the inner surface of the downstream diverter47is typically just large enough for the tube22to reasonably pass therethrough without any unwanted effects. As mentioned above, Teflon brand coatings, or other suitable materials for reducing friction, and the hot air supplied by the downstream plenum50dmay reduce friction and thereby aid the tube22in passing through the narrow clearance between the downstream diverter47(FIGS. 1-4) and the downstream plenum50d. For example the upper rows of discharge ports in the downstream air outlets48d,48emay be no more than about one inch from the convexly curved top edge of the downstream plenum50d, so that a sufficient amount of lubricating hot air reaches the outer surface of the convexly curved top edge of the downstream plenum.FIG. 10schematically shows the folded-over upper end of the tube22being introduced into the nipping apparatus76for nipping.

The tube22with its ends unsealed is discussed in greater detail in the following with reference toFIGS. 11-14, in accordance with the first embodiment.FIG. 11shows the tube22with its optional side pleats91folded inwardly. In contrast, the front and rear views ofFIGS. 12 and 13show the pleats91folded outwardly, although the pleats typically remain folded inwardly at least until after the bag containing the pleats is filled. The pleats91are defined by lines of disruption92(e.g., fold lines).FIG. 14is a top perspective view of the interior of the tube22in an open configuration, with the pleats91folded inwardly.FIGS. 12 and 13are schematic because, for example, they include dashed lines for schematically identifying that the front side of the tube22includes a first outer (marginal) portion O1of the tube and a second outer portion O2of the tube, and the rear side of the tube includes a third outer (marginal) portion O3of the tube and a fourth outer portion O4of the tube.FIG. 14is schematic because, for example, it includes dashed lines for schematically identifying that the interior surface of the front side of the tube22includes first and second inner portions11,12that respectively correspond to the first and second outer potions O1, O2, and the interior surface of the rear side of the tube22includes third and fourth inner portions13,14that respectively correspond to the third and fourth outer potions O3, O4. Similarly, each pleat91is schematically shown as including surface portions P1, P2, P3, P4. The pleats91may be omitted.

In accordance with the first embodiment, the tube22comprises a sheet of packaging material100(FIG. 15) with opposite edges that have been joined together at a longitudinal seal93(FIGS. 11,12and14) that extends been the opposite ends of the tube and may be in the form of a foldover seal, fin seal, or any other suitable seal, or the like. In accordance with the first embodiment and as shown in the figures herewith, the edges at the opposite ends of the tube22are “straight cut” (e.g., at least substantially straight cut (i.e., not step cut)). Alternatively, the edges may not be required to be “straight cut.”

The packaging material100from which the tube22may be constructed is described in the following with reference toFIG. 15, in accordance with the first embodiment. The packaging material100generally includes a substrate102(any suitable substrate (e.g., a high strength substrate) such as, but not limited to, paper, polymer film, or a woven polymer substrate) and a pair of facing systems104,106, each of which may include one or more layers that are coextruded and/or otherwise joined to one another. Such layers may include polymer films, polymer or polymeric coatings or layers, paper layers, other woven materials or nonwoven materials, or any other suitable material. In accordance with the first embodiment, the substrate102is a woven polymer substrate, although other substrates may be used. Each facing system104,106of the packaging material100includes an outermost surface108,110that respectively defines the inner (i.e., interior) and outer (i.e., exterior) sides or faces108,110of the packaging material100. Each side108,110of the packaging material100includes (or is provided with) at least one area or zone (e.g., one or more of outer portions O1-O4and inner portions I1-I4) that is capable of being joined to the respective surface of the packaging material100using a heat sealable material, adhesive, or otherwise. More specifically and in accordance with the first embodiment, the entirety of the interior and exterior surfaces of the tube22comprise (e.g., are constructed of or have had applied thereto) a heat sealable material.

A bag112(FIGS. 16-18) formed form the tube22by the sealing system20, and an example of a suitable method for forming the bag, are discussed in the following, in accordance with the first embodiment. The side pleats91of the bag112typically remain folded inwardly until the bag is filled. The end of the bag112includes a shear seal closure114that includes both a pinch seal116and a foldover seal118. Referring toFIGS. 12-14,17and18, in the pinch seal116:all (e.g., substantially all) of the portions of the inner portions I1, I3that are in opposing face-to-face relation with one another are in opposing face-to-face contact with one another and are sealed to one another;at each pleat91, all (e.g., substantially all) of the surface portions P1, P2are in opposing face-to-face contact with one another and are sealed to one another;at each pleat91, all (e.g., substantially all) of the surface portion P3and the inner portion I1are in opposing face-to-face contact with one another and are sealed to one another; andat each pleat91, all (e.g., substantially all) of the surface portion P4and the inner portion I3are in opposing face-to-face contact with one another and are sealed to one another.
In the foldover seal118, all (e.g., substantially all) of the outer portions O1, O2are in opposing face-to-face contact with one another and are sealed to one another. In accordance with the first embodiment, when the sealing system20is used to form the shear seal closure114, the sealing system operates in a manner that seeks to avoid formation of any seals in addition to those discussed immediately above for the shear seal closure114/pinch seal116/foldover seal118, in order to maximize the volume of the interior of the bag112. For example, unsealed areas94are identified inFIGS. 17 and 18. Alternatively, additional seals or sealed areas may be included.

An example of a method of forming the shear seal closure114is described in the following, in accordance with the first embodiment. The flattened tube22, with its pleats91folded inwardly, is introduced into the upstream end of the sealing system20. The tube22is introduced so that the longitudinal seal93faces forwardly (as shown inFIGS. 7 and 8) and the imaginary demarcation (e.g., see the respective dashed line inFIG. 12) between the outer portions O1, O2is at substantially the same elevation as the upstream diverter46. Therefore, when the tube22engages the upstream diverter46, the upstream diverter begins to form a fold/fold line in the tube at the imaginary demarcation between the outer portions O1, O2.

Then, as the partially folded tube22continues to be carried downstream by the transport conveyor26, the air outlets48a,48b,48c(FIG. 4) are respectively in opposing face-to-face relation with and discharge hot air against the outer portions O3, O1so that the outer portions O3, O1are heated by forced convention. The air outlets48a,48bare opposite from one another. Similarly, the air outlets48a,48care opposite from one another. In addition, the outer portions O3, O1are opposite from one another.

The surfaces that are sealed together as part of the pinch seal116(FIGS. 17 and 18) may comprise (or have applied to at least a portion thereof) a heat sealable and/or adhesive material, for example, a heat sealable polymer film, a heat sealable coating, a hot melt adhesive, or any other suitable material for forming the pinch seal116, as needed to create the desired heat seal (e.g., to provide strength, protection from contamination or infestation by insects, and so on). When exposed to heat, the heat sealable and/or adhesive material is operative for joining the surfaces that are sealed together as part of the pinch seal116. In accordance with the first embodiment, the pinch seal116extends all the way (substantially all the way) from one side of the bag112to the other side of the bag. However, it will be appreciated that the pinch seal116may be spaced from the opposite edges of the bag112and/or may have other transverse and/or longitudinal dimensions.

The pinch seal116may generally be formed at a temperature below the distortion or softening temperature of the woven polymer substrate102(FIG. 15) and/or any other components of the packaging material100that are not intended to be softened. For example, where the woven polymer substrate102comprises polypropylene, which typically softens at about 350° F., the heat seal temperature for forming the pinch seal116may generally be less than about 350° F., for example, from about 250° F. to about 300° F., or to about 325° F. Accordingly, the air outlets48a,48b,48cthat are respectively in opposing face-to-face relation with and discharge hot air against the outer portions O3, O1provide the hot air at a temperature that is high enough to provide the heat seal temperature for forming the pinch seal116, yet not so high so as to cause the woven polymer substrate102to reach its softening temperature. The desired or required temperature of the hot air discharged by the air outlets48a,48b,48cmay depend upon various factors such as, but not limited to, the dwell time (e.g., how quickly the tube22is transported through the sealing system20).

As the partially folded, heated tube22continues to be carried downstream by the transport conveyor26, the tube22engages the downstream diverter47which completes (e.g., substantially completes) folding the tube so that the tube is in the folded-over configuration that is schematically shown inFIG. 9(e.g., the substantially one hundred eight degree folded-over configuration). As best understood with reference toFIG. 9and for example, while the tube22is in the folded-over configuration: the first and second outer portions O1, O2of the tube22are facing substantially toward one another, and the third and fourth outer portions O3, O4of the tube are facing substantially away from one another.

At about the same time that the downstream diverter47substantially provides the folded-over configuration of the tube22, the air outlets48d,48e,48f(FIG. 9) are respectively in opposing face-to-face relation with and discharge air against the outer portions O1, O2, O4so that heat is transferred with respect to the outer portions O1, O2, O4by way of forced convention. The air outlets48d,48eare opposite from one another. Similarly, the air outlets48e,48fare opposite from one another. The air outlets48d,48fmay also be characterized as being opposite from one another. In addition, the outer portions O3, O1are opposite from one another. While the tube22is in the folded-over configuration, outer portions O1, O2are opposite from one another. The outer portions O1, O4may also be characterized as being opposite from one another, and the outer portions O3, O2may also be characterized as being opposite from one another.

More specifically, the air outlets48d,48edischarge hot air against the outer portions O1, O2so that the outer portions O1, O2are heated by forced convention; and the air outlet48fdischarges cool air or air at ambient temperature (e.g., relatively cool air) against the outer portion O4so that the outer portion O4is cooled by forced convention. The above-discussed heating by forced convection is for helping to facilitate forming of the above-discussed seals of the shear seal closure, and the above-discussed cooling by forced convection is for helping to avoid forming any more than the seal between the outer portions O1, O2when the foldover seal118is formed.

The surfaces that are sealed together as part of the foldover seal118may comprise (or have applied to at least a portion thereof) a heat sealable and/or adhesive material, for example, a heat sealable polymer film, a heat sealable coating, a hot melt adhesive, or any other suitable material for forming the foldover seal118, as needed to create the desired heat seal (e.g., to provide strength, protection from contamination or infestation by insects, and so on). When exposed to heat, the heat sealable and/or adhesive material is operative for joining the surfaces that are sealed together as part of the foldover seal118. In accordance with the first embodiment, the foldover seal118extends all the way (substantially all the way) from one side of the bag112to the other side of the bag. However, it will be appreciated that the foldover seal118may be spaced from the opposite edges of the bag112and/or may have other transverse and/or longitudinal dimensions.

The foldover seal118may generally be formed at a temperature below the distortion or softening temperature of the woven polymer substrate102(FIG. 15) and/or any other components of the packaging material100that are not intended to be heat sealed. For example, where the woven polymer substrate102comprises polypropylene, which typically softens at about 350° F., the heat seal temperature for forming the foldover seal118may generally be less than about 350° F., for example, from about 250° F. to about 300° F., or to about 325° F. Accordingly, the air outlets48b,48c,48d,48e, that are respectively in opposing face-to-face relation with and discharge hot air against the outer portions O2, O1provide the hot air at a temperature that is high enough to provide the heat seal temperature for forming the foldover seal118, yet not so high so as to cause the woven polymer substrate102to reach its softening temperature.

Reiterating from above, if needed, air substantially at ambient temperature or cooled air may be directed by the air outlet48fagainst the outer portion O4in a manner that seeks to prevent the interior surfaces108of the tube22from being joined to one another behind the foldover seal118(which would reduce the volume of the interior space of the bag112). However, other possibilities are contemplated. The desired or required temperature of the air discharged by the air outlets48d,48e,48fmay depend upon various factors such as, but not limited to, the dwell time (e.g., how quickly the tube22is transported through the sealing system20).

The heat sealable and/or adhesive material may lie outside of the area in which the foldover seal118and the pinch seal116are to be formed. For example, all or a portion of the interior or exterior surfaces108,110of the tube22may comprise a heat sealable polymer film or polymeric material.

The nipping apparatus76nips the upper portion of the tube22in the folded-over configuration to simultaneously (e.g., substantially simultaneously) complete the formation of the pinch seal116and the foldover seal118. Then, the resulting bag112is discharged from the downstream end of the sealing system20/conveyor assembly42/nipping apparatus76.

A second embodiment of this disclosure is like the first embodiment, except for variations noted in this disclosure and variations that will be apparent to one of ordinary skill in the art.FIG. 19is a schematic cross-sectional view of a portion of a bag of the bag112′ second embodiment, with the cross section taken similarly to that ofFIG. 17; andFIG. 20is a schematic cross-sectional view of a portion of the bag112′ of the second embodiment, with the cross section taken similarly to that ofFIG. 18. The sealed closure of the bag112′ of the second embodiment is not folded over, and it only includes the pinch seal116(i.e., the foldover seal118(FIGS. 17 and 18) is omitted). In accordance with one acceptable example, the closure of the bag112′ of the second embodiment may be formed in the sealing system by20by introducing the tube22so that the top edge of the tube is slightly below the elevation as the upstream diverter46(i.e., the tube is not folded) and hot air is discharged by both of the air outlets48e,48f(FIG. 5). The other air outlets48a,48b,48c,48dmay be disabled or otherwise not used, or the like. That is, it is within the scope of this disclosure for a user of the sealing system20to select the air outlets to be used/not to be used, depending upon the circumstances. For example, dampers70(FIG. 6) and/or other types of valves and/or any other suitable controlling devices may be included in the sealing system20, or more specifically in the forced air systems58(FIG. 6), for selectively controlling (e.g., disabling or enabling) flow to one or more of the above-discussed plenums and/or air outlets.

A third embodiment of this disclosure is like the first embodiment, except for variations noted in this disclosure and variations that will be apparent to one of ordinary skill in the art.FIG. 21is a schematic cross-sectional view of a portion of a bag112″ of the third embodiment, with the cross section taken similarly to that ofFIG. 17; andFIG. 22is a schematic cross-sectional view of a portion of the bag112″ of the third embodiment, with the cross section taken similarly to that ofFIG. 18. In accordance with one acceptable example, the closure of the bag112″ of the third embodiment may be formed in the sealing system by20by passing the upper end of the bag112ofFIG. 16through the sealing system a second time, to substantially repeat the method of the first embodiment, and therefore form a double shear seal closure.

A fourth embodiment of this disclosure is like the third embodiment, except for variations noted in this disclosure and variations that will be apparent to one of ordinary skill in the art.FIG. 23is a schematic cross-sectional view of a portion of a bag112′″ of the fourth embodiment, with the cross section taken similarly to that ofFIG. 17. In the double shear seal closure of the bag112′″ of the fourth embodiment, the end/pinch seal farthest from the interior of the bag is extended, and an integral grasping feature or handle generally comprising an aperture95or cutout extends through the pinch seal farthest from the interior of the bag. A flap may be retained in the aperture95, such as for providing cushioning against a hand inserted into the aperture.

Countless packaging materials100(FIG. 15) may be used in accordance with the present disclosure to form any of the constructs and structures (e.g., tubes and bags) described above, with the substrate102and facing systems104,106being selected to impart various properties to the resulting packaging material. By way of illustration, and not limitation, several exemplary packaging materials200,300,400are illustrated schematically inFIGS. 24-26. Each packaging material200,300,400generally includes a woven polymer substrate202,302,402and a respective pair of facing systems104,106;204,206;304,306, each of which may include a plurality of layers, as discussed above in connection withFIG. 15. For purposes of convenience, some layers of the packaging materials200,300,400may be described as “overlying” or being disposed “on” other layers. However, it will be appreciated that each packaging material200,300,400may be inverted, such that other layers may be said to “overlie” or be disposed “on” one another. Accordingly, such terminology is provided merely for convenience of explanation and not limitation in any manner.

It will also be appreciated that numerous other packaging materials are contemplated by the disclosure, and that each of such packaging materials may include various layers. Layers may be added or omitted as needed. It also will be appreciated that various materials may be used to form each layer of the packaging material, and that each layer may have various basis weights or coat weights and may be present in the packaging material in any suitable relative amount, depending on the particular application. Further, it will be appreciated that each layer may serve more than one purpose in a particular packaging material, and that the layer names are provided for convenience of explanation and not limitation in any manner.

Turning now toFIG. 24, a first exemplary packaging material200includes a woven polymer substrate202, a first facing system204comprising a first polymer film layer212and a tie layer (e.g., a first tie layer)214disposed between the substrate202and the first polymer film layer212, and a second facing system206comprising a second polymer film layer216, which may be optionally printed with ink218, and a tie layer (e.g., a second tie layer)220disposed between the substrate202and the second polymer film layer216. Each layer202,212,214,216,218,220is in a substantially facing, contacting relationship with the respective adjacent layer(s). Alternatively, in other embodiments, the second polymer film layer216may be reverse printed such that the ink218lies between the second polymer film layer216and the second tie layer220.

When used to form a package, the first polymer film layer212(i.e., the outermost surface of the first polymer film layer212) generally faces inwardly and/or defines the interior surface208of the tube, bag, package or the like, and the second polymer film layer216(i.e., the outermost surface of the second polymer film layer216and/or ink218, where present) generally defines the exterior surface210of the tube, bag, package or the like. Accordingly, one or both polymer film layers212,216may comprise heat sealable materials.

The substrate202generally comprises a base material from which the packaging material is formed. In one particular embodiment, the substrate202may comprise a woven polymer, for example, a woven polypropylene. The substrate202may have a denier of from about 600 to about 1200 dpf (denier per filament), for example, from about 700 to 1000 dpf, and in one example, the substrate202comprises a woven material having a denier of about 850 dpf. Likewise, the substrate202may have any suitable weave, for example, from about 8×8 to about 12×12, for example, about 10×10. In one particular example, the substrate202comprises a woven polypropylene having a denier of about 850 dpf and a 10×10 weave. One example of such a material is commercially available from Mayur Wovens Pvt., Ltd. (India). However, countless other deniers, ranges of deniers, weaves, ranges of weaves, and other substrates may be used.

The first polymer film layer212and the second polymer film layer216may be used to impart strength, water resistance, heat sealability, and/or other attributes to the packaging material200. Where heat sealability is desired, one or both polymer films212,216may generally comprise a thermoplastic polymer having a sufficiently low melting or softening point so the heat seal can be initiated at a relatively low temperature (“heat seal temperature”), for example, from about 180° F. to about 300° F. Additionally, the polymer may be selected to provide a wide hot tack sealing window, such that the heat seal may be formed over a range of temperatures with the degree of tackiness for the desired duration.

The polymer film layers212,216may generally have any suitable thickness (i.e., caliper), for example, from about 0.4 to about 1.5 mil, for example, from about 0.5 to about 1.2 mil. In one example, one or both polymer film layers212,216may have a thickness of about 0.7 mil. In another example, one or both polymer film layers212,216may have a thickness of about 1 mil. However, other suitable thicknesses and ranges of thicknesses are contemplated.

In one particular example, the first polymer film layer212may comprise low density polyethylene (LDPE). In one variation of this example, the first polymer film layer212may have a thickness of from about 0.5 to about 3 mil, for example, from about 0.8 to about 1.5 mil, for example, about 1 mil. However, other suitable materials are contemplated.

In another particular example, the second polymer film layer216may comprise biaxially oriented polypropylene (BOPP). In one variation of this example, the second polymer film layer216may have a thickness of from about 0.4 to about 1 mil, for example, from about 0.6 to about 0.8 mil, for example, about 0.7 mil. However, other suitable materials are contemplated.

In still another particular example, the first polymer film layer212may comprise LDPE having a thickness of from about 0.8 to about 1.5 mil, for example, about 1 mil, and the second polymer film layer216may comprise BOPP having a thickness of from about 0.4 to about 1 mil, for example, about 0.7 mil. However, numerous other configurations of layers are contemplated.

It will be appreciated that in an alternative embodiment, layers212and/or216may be used to provide strength and/or water resistance, while one or more other layers (not shown) may be provided for heat sealability. Countless possibilities are contemplated.

The tie layers214,220generally serve to join two adjacent layers, but may have additional functionality if desired. In this example, tie layer214is generally operative for joining the first polymer film layer212and the substrate202, and tie layer220is generally operative for joining the second polymer film layer216and the substrate202.

Each tie layer214,220may have any suitable composition and basis weight needed to attain the desired level of adhesion between the adjacent layers. For example, where the adjacent layers comprise PP (e.g., layers202,216), tie layer220may comprise PP. One example of a PP that may be suitable as a tie layer220is HMX370or HMX340, commercially available from Chevron.

As another example, where the adjacent layers (e.g., layers202,212) comprise PP (e.g., layer202) and LDPE (e.g., layer212), the tie layer214may comprise a blend of polymers. The blend may include one or more components that provide adhesion to the substrate202and one or more components that provide adhesion to the first polymer film layer212.

In one particular example, the blend may comprise a blend of linear low density polyethylene (LLDPE), for example, metallocene catalyzed LLPDE (“m-LLDPE”) and LDPE. The present inventors have discovered that this exemplary blend provides superior processability and adhesive properties. One example of an LLDPE that may be suitable for use is Dow Affinity PT 1450G1 (Dow Chemical Co., Midland, Mich.) (believed to be m-LLDPE). While not wishing to be bound by theory, it is believed that Dow Affinity PT 1450G1 LLDPE may include one or more components that may enhance the adhesion with PP. One example of an LDPE that may be suitable is Chevron 1018 LDPE (Chevron Phillips Chemical Co. LLC, The Woodlands, Tex.). Other examples of LDPEs that may be suitable include, but are not limited to, Westlake EC-482 (Westlake Chemical Corp., Houston, Tex.) and Marfiex® 1013 LDPE (Phillips Chemical Co. LLC, The Woodlands, Tex.).

The relative amounts of LLDPE (e.g., m-LLDPE) and LDPE in the tie layer214may vary for each application. The blend may generally comprise from about 70% to about 95% LLDPE and about 5% to about 30% LDPE (by weight), for example, from about 80% to about 90% LLDPE and about 10% to about 20% LDPE. In one exemplary embodiment, the blend may comprise about 85% LLDPE and about 15% LDPE. However, other suitable amounts and ratios of LDPE and PP may be used.

In other embodiments, the tie layer214may comprise a blend of PP and LDPE. Numerous other possibilities are contemplated.

Each tie layer214,220may have any suitable basis weight, for example, from about 1 to about 15 lb/ream, for example, from about 6 to about 10 lb/ream. In one specific example, one of the tie layers214,220has a basis weight of about 8 lb/ream. In another example, both of the tie layers214,220have a basis weight of from about 8 lb/ream. However, other basis weights and ranges of basis weights are contemplated.

FIG. 25schematically illustrates another exemplary packaging material300. The packaging material300includes a substrate302including a pair of opposed sides, a first facing system304including a tie layer312(e.g., a first tie layer), a core layer314, and a heat seal layer316disposed on a first side of the substrate302, and a second facing system306including a polymer film layer318, which may optionally be printed with an ink320, and a tie layer322(e.g., a second tie layer) disposed on a second side of the substrate302. In an alternative embodiment (not shown), the polymer film layer318may include printing (i.e., ink320) on the exterior surface310of the film318.

Each layer or material302,312,314,316,318,320,322is in a substantially facing, contacting relationship with the respective adjacent layer(s) or material. When used to form a package, polymer film layer318(i.e., the outermost surface310of polymer film layer318) generally faces outwardly and/or at least partially defines the exterior surface310of the tube, bag, package or the like, and heat seal layer316(i.e., the outermost surface308of heat seal layer316) generally faces inwardly and/or defines the interior surface308of the tube, bag, package or the like.

The substrate302may be any suitable material, for example, the woven polymer materials described in connection withFIG. 24.

Layers312,314,316generally define a multifunctional polymer system304. The polymer system304may be used to impart numerous properties to the packaging material300. Thus, while the layers of the polymer system304may be described independently, it will be appreciated that the layers cooperate with one another to enhance the packaging material300, as will be discussed below.

The heat seal layer316generally renders the interior side308of the packaging material300heat sealable. This may be desirable for numerous package configurations. The core layer314generally comprises a polymer layer, which may, if desired, impart various attributes to the packaging material300. By way of example, and not limitation, the core layer314may serve as a barrier layer to oils (i.e., as an oil resistant layer). This may be important where the contents of the tube, bag, package or the like include a fatty or oily component, for example, as with pet food, bird seed, etc. The tie layer312generally joins the core layer314to the substrate302. However, in some embodiments, the tie layer may be omitted, such that the core layer314also serves as a tie layer.

In some instances, the core layer314may be selected to have a melting point that is greater than the heat seal temperature to ensure that the integrity of the core layer314is maintained during the heat sealing process. In other instances, the core layer314may comprise a blend of materials, at least one of which may have a melting point less than the heat seal temperature. In such embodiments, the lower melting component(s) may soften during the heat sealing process, such that a portion of the core layer314serves as a heat seal material or layer in conjunction with heat seal layer316. Thus, depending on the materials selected, each of the various layers312,314,316may cooperate in various ways to achieve a desired result.

In one exemplary embodiment, the heat seal layer316may comprise a blend of low density polyethylene (LLDPE), low density polyethylene (LDPE), and an ethylene/methacrylic acid copolymer (EMA). The LLDPE may be a metallocene LLDPE (m-LLDPE). The ratio of each component may vary for each application. In one example, the blend may comprise from about 60% to 100% LLDPE, from 0 to about 35% LDPE, and from 0 to about 5% EMA. In another example, the blend may comprise from about 60% to about 80% LLDPE, from about 15% to about 35% LDPE, and from about 1 to about 5% EMA. In still another example, the blend may comprise about 60% LLDPE, about 35% LDPE, and about 5% EMA, such that the ratio of the components is about 12:7:1. However, other blends of LLDPE, LDPE, and EMA are contemplated.

The present inventors have found that a blend of LLDPE, LDPE, and EMA offers superior processability and resulting heat seal strength. Specifically, the present inventors have found that by adding LLDPE to LDPE, the melting point (and, therefore, the heat seal temperature) is lowered from about 230° F. to about 220° F., and that by adding EMA to the mixture of LLDPE and LDPE, the melting point (and, therefore, the heat seal temperature) of the blend is lowered to about 210-215° F. As a result, the heat seal may be initiated at a lower temperature, which allows for the packaging material300to be heat sealed at greater processing speeds. The present inventors have also found that the heat seal formed from the blend of LLDPE, LDPE, and EMA has superior strength relative to a heat seal formed from any of the individual components.

While various LLPDEs, LDPEs, and EMAs may be used, one example of an LLDPE that may be suitable for use is Dow Affinity PT 1450G1 (Dow Chemical Co., Midland, Mich.) (believed to be m-LLDPE). While not wishing to be bound by theory, it is believed that Dow Affinity PT 1450G1 LLDPE may include one or more components that may enhance the affinity with PP. One example of an LDPE that may be suitable is Chevron 1018 LDPE (Chevron Phillips Chemical Co. LLC, The Woodlands, Tex.). Other examples of LDPEs that may be suitable are set forth above in connection with the discussion of the exemplary packaging material200ofFIG. 24.

The heat seal layer316may have any suitable basis weight, for example, from about 1 to about 5 lb/ream, for example, from about 2 to about 4 lb/ream, for example, about 3 lb/ream. In one specific example, the heat seal layer316has a basis weight of about 3.06 lb/ream. However, other basis weights and ranges thereof are contemplated.

The tie layer312may be formed from any suitable material that sufficiently adheres to (and therefore joins) the adjacent layers. In one example, the tie layer312may comprise a blend of LLDPE, LDPE, and EMA, as described above. The ratio of each component may vary for each application. In one variation, the blend may comprise from about 60% to 100% LLDPE, from 0 to about 35% LDPE, and from 0 to about 5% EMA. In another variation, the blend may comprise from about 60% to about 80% LLDPE, from about 15% to about 35% LDPE, and from about 1 to about 5% EMA. In still another variation, the blend may comprise about 60% LLDPE, about 35% LDPE, and about 5% EMA, such that the ratio of the components is about 12:7:1. Other blends of LLDPE, LDPE, and EMA are contemplated.

The present inventors have discovered that this exemplary blend provides superior processability and adhesive properties with a variety of substrates. By way of illustration, and not limitation, it is known that it is difficult to adhere various polymers layers to polypropylene (PP) (e.g., in the substrate302) at high processing speeds. However, the exemplary blend of LLDPE, LDPE, and EMA, which has a relatively low melting point (about 210-215° F. as compared with about 350° F. for PP), tends to flow readily into the spaces between the woven filaments, even at high processing speeds (e.g., 2000-2500 ft/min). Additionally, where Dow Affinity 1450G1 LLPDE is used, the present inventors have found that the tie layer312has a greater affinity for core layers including PP (e.g., core layer314), as compared with other LLDPEs. As stated above, while not wishing to be bound by theory, it is believed that the Dow Affinity 1450G1 LLDPE includes one or more components that enhance the affinity of the LLPDE to PP.

The tie layer312may have any suitable basis weight, for example, from about 0.5 to about 5 lb/ream, for example, from about 0.75 to about 2 lb/ream, for example, about 1 lb/ream. In one specific example, the tie layer312has a basis weight of about 1.19 lb/ream. Other ranges and basis weights are contemplated.

In one exemplary embodiment, the core layer314may comprise a blend of PP and LDPE. The relative amounts of PP and LDPE in the core layer314may vary for each application. The blend may generally comprise from about 70% to about 90% PP and about 10% to about 30% LDPE. In each of various examples, the blend may comprise about 75% PP and about 25% LDPE, about 80% PP and about 20% LDPE, or about 85% PP and about 15% LDPE. However, other suitable amounts and ratios of LDPE and PP may be used.

The present inventors have discovered these exemplary blends of PP and LDPE in the core layer314provide an excellent balance of properties for various packaging materials. For example, as compared with a core layer314comprising only PP (i.e., without the LDPE), a core layer314including from about 80 to about 85% PP and about 15 to 20% LDPE (by weight) provides about the same level of oil resistance as a core layer314comprising 100% PP. Further, the presence of the LDPE improves adhesion with the adjacent layers. By way of example, where the heat seal layer316and/or the tie layer312comprise a blend of LLDPE, LDPE, and EMA (e.g., as discussed above), the blend of LDPE and PP in the core layer314has a greater affinity for the polymer blend of the heat seal layer316and/or the tie layer312, as compared with PP alone.

Further, since LDPE has a lower melting point than PP (about 230° F. for LDPE and about 320° F. for PP), in some cases, depending on the heat seal temperature and other processing conditions, the LDPE in the core layer314and the tie layer312may soften during the heat sealing process, such that a part of the core layer314and tie layer312also effectively serves as part of the heat seal layer316. In such cases, the basis weight of the heat seal layer316and/or the tie layer312may be reduced, thereby reducing the cost of the overall structure.

By way of illustration, the present inventors have found that a packaging material including:a heat seal layer316having a basis weight of about 1.3 lb/ream and comprising a blend of about 60% LLDPE, about 35% LDPE, and about 5% EMA (by weight);a core layer314having a basis weight of about 3.33 lb/ream and comprising an 80/20 blend of PP/LDPE; anda tie layer312having a basis weight of about 0.37 lb/ream and comprising a blend of about 60% LLDPE, about 35% LDPE, and about 5% EMA, exhibited better peel strength (i.e., layer to layer adhesion) than a packaging material including:a heat seal layer316having a basis weight of about 3.12 lb/ream and comprising a blend of about 60% LLDPE, about 35% LDPE, and about 5% EMA;a core layer314having a basis weight of about 4 lb/ream and comprising PP; anda tie layer312having a basis weight of about 0.88 lb/ream and comprising a blend of about 60% LLDPE, about 35% LDPE, and about 5% EMA.
Thus, although each polymer system304had about the same basis weight (about 5 lb/ream), the packaging material including the blend of LDPE and PP in the core layer314exhibited superior peel strength at a reduced cost (based on the present cost of various polymers in each layer). While not wishing to be bound by theory, it is believed that this is because the presence of the LDPE in the core layer contributed to the overall heat sealability of the material, as discussed above.

The core layer314may generally have a basis weight of from about 1 to about 8 lb/ream, for example, from about 2 to about 6 lb/ream, for example, about 4 lb/ream. In one specific example, the basis weight of the core layer314may be about 3.75 lb/ream. Other ranges and basis weights are contemplated.

The polymer system304(i.e., the heat seal layer316, core layer314, and tie layer312) may have any suitable total basis weight. In each of various examples, the polymer system304may have a basis weight of about 5 lb/ream, about 5.5 lb/ream, about 6 lb/ream, about 6.5 lb/ream, about 7 lb/ream, about 7.5 lb/ream, about 8 lb/ream, about 8.5 lb/ream, about 9 lb/ream, about 9.5 lb/ream, about 10 lb/ream, about 10.5 lb/ream, about 11 lb/ream, about 11.5 lb/ream, about 12 lb/ream, about 12.5 lb/ream, about 13 lb/ream, about 13.5 lb/ream, about 14 lb/ream, about 14.5 lb/ream, about 15 lb/ream, or any other suitable basis weight.

Further, the components of the polymer system304may be present in any suitable ratio. In one example, the weight % ratio of the heat seal layer316, core layer314, and tie layer312may be about 3.06:3.15:1. However, other ratios are contemplated.

In one example, the heat seal layer316may have a basis weight of from about 1 to about 5 lb/ream, the core layer314may have a basis weight of from about 1 to about 8 lb/ream, and the tie layer312may have a basis weight of from about 0.5 to about 5 lb/ream.

In another example, the heat seal layer316may have a basis weight of from about 2 to about 4 lb/ream, the core layer314may have a basis weight of from about 2 to about 6 lb/ream, and the tie layer312may have a basis weight of from about 0.75 to about 2 lb/ream. In one particular example, the heat seal layer316may have a basis weight of about 3 lb/ream, the core layer314may have a basis weight of about 4 lb/ream, and the tie layer312may have a basis weight of about 1 lb/ream. In another particular example, the heat seal layer316may have a basis weight of about 3.06 lb/ream, the core layer314may have a basis weight of about 3.75, and the tie layer312may have a basis weight of about 1.19 lb/ream.

The polymer film layer318may be used to impart strength, water resistance, heat sealability, and/or other attributes to the packaging material300. Where heat sealability is desired, the polymer film318may generally comprise a thermoplastic polymer having a sufficiently low melting or softening point so the heat seal can be initiated at a relatively low temperature (“heat seal temperature”), for example, from about 180° F. to about 300° F., as discussed above in connection with polymer film layers212,216ofFIG. 24. Examples of polymers that may be suitable for the polymer film layer318are also discussed in connection with polymer film layers212,216ofFIG. 24.

The polymer film layer318may have any suitable thickness (i.e., caliper) of, for example, from about 0.4 to about 1.5 mil, for example, from about 0.5 to about 1.2 mil. In one example, the film may have a thickness of about 0.7 mil. However, other suitable thicknesses and ranges of thicknesses are contemplated.

In one particular example, the polymer film layer318may comprise biaxially oriented polypropylene (BOPP). In one variation of this example, the polymer film layer318may have a thickness of from about 0.4 to about 1 mil, for example, from about 0.6 to about 0.8 mil. In one variation of this example, the polymer film layer318may have a thickness of about 0.7 mil. However, other suitable materials are contemplated.

The tie layer322generally serves to join the two adjacent layers, in this example, the polymer film layer318and the substrate302, but may provide functionality if desired. The tie layer322may have any suitable composition and basis weight as needed to attain the desired level of adhesion between the adjacent layers. In one particular example, the blend may comprise a blend of linear low density polyethylene (LLDPE), for example, metallocene catalyzed LLPDE (“m-LLDPE”) and LDPE. The present inventors have discovered that this exemplary blend provides superior processability and adhesive properties. One example of an LLDPE that may be suitable for use is Dow Affinity PT 1450G1 (Dow Chemical Co., Midland, Mich.) (believed to be m-LLDPE). While not wishing to be bound by theory, it is believed that Dow Affinity PT 1450G1 LLDPE may include one or more components that may enhance the adhesion with PP. One example of an LDPE that may be suitable is Chevron 1018 LDPE (Chevron Phillips Chemical Co. LLC, The Woodlands, Tex.). Other examples of LDPEs that may be suitable include, but are not limited to, Westlake EC-482 (Westlake Chemical Corp., Houston, Tex.) and Marflex® 1013 LDPE (Phillips Chemical Co. LLC, The Woodlands, Tex.). However, numerous other possible tie layers are contemplated.

The relative amounts of LLDPE (e.g., m-LLDPE) and LDPE in the tie layer322may vary for each application. The blend may generally comprise from about 70% to about 95% LLDPE and about 5% to about 30% LDPE (by weight), for example, from about 80% to about 90% LLDPE and about 10% to about 20% LDPE. In one exemplary embodiment, the blend may comprise about 85% LLDPE and about 15% LDPE. However, other suitable amounts and ratios of LDPE and PP may be used.

The tie layer322may have any suitable basis weight, for example, from about 1 to about 15 lb/ream, for example, from about 6 to about 10 lb/ream. In one specific example, the tie layer322has a basis weight of about 8 lb/ream. However, other basis weights and ranges of basis weights are contemplated.

FIG. 26schematically illustrates an alternate packaging material400. The packaging material400includes features that are similar to the packaging material300ofFIG. 25, except for variations noted and variations that will be understood by those of skill in the art. For simplicity, the reference numerals of similar features are preceded in the figures with a “4” instead of a “3”.

In this example, layers318,320,322of the packaging material300ofFIG. 25are replaced with a polymer system406similar to that of polymer system404. Specifically, the packaging material400includes a substrate402including a pair of opposed sides, a first tie layer412, a first core layer414, and a first heat seal layer416disposed on a first side of the substrate402, and a second tie layer424, a second core layer426, and a second heat seal layer428disposed on a second side of the substrate402, such that the arrangement of layers is generally symmetrical. If desired, the outermost surface408,410of layers416and/or428may be printed with ink (not shown).

Each pair of layers (e.g., the first and second heat seal layers416,418, the first and second core layers414,426, and the first and second tie layers412,424) independently may have the same or different composition and/or weight. Exemplary basis weights are provided above with respect to the packaging material300ofFIG. 25.

As with the packaging material300ofFIG. 25, either or both of layers412,424may be omitted, such that layers414,426serve as tie layers that join the heat seal layers416,428to the respective sides of the substrate402.

While numerous possibilities are contemplated, this packaging material400may find particular use where less strength is needed and/or where a lower cost alternative is desired.

In still another exemplary embodiment (not shown), one or both of the facing systems may comprise a layer of paper that defines the first and/or second surface of the packaging material. It will be appreciated that shear seals and/or other seals may be formed from such materials using a hot melt adhesive or other adhesive material. Numerous other possibilities are contemplated.

Various aspects of the present invention are illustrated further by the following example, which is not to be construed as limiting in any manner.

A packaging material having the following structure was made by extrusion laminating the polymer film layers to the woven substrate:about 0.7 mil BOPP film;about 8 lb/ream PP;about 850 dpf 10×10 woven PP substrate;about 8 lb/ream blend of 80% Dow Affinity m-LLDPE+20% LDPE;about 1 mil LDPE film

Various properties of the packaging material were measured. The results are set forth in Table 1, in which all values are approximate.

All directional references (e.g., upper, lower, upward, downward, left, right, leftward, rightward, top, bottom, above, below, vertical, horizontal, upstream and downstream) are used in the Detailed Description section of this disclosure only for identification purposes to aid the reader's understanding of the various embodiments, and do not create limitations, particularly as to the position, orientation, or use of the invention unless specifically set forth in the following claims.

It will be understood by those skilled in the art that while the present disclosure has been discussed above with reference to several embodiments, various additions, modifications and changes can be made thereto without departing from the spirit and scope of the invention as set forth in the claims.