Reclosable packages with two-dimensional zipper attachement

Abstract

A reclosable package having a two-dimensional zipper attachment on the exterior of one wall. The zipper comprises a pair of zipper strips that have straight central sections and end sections that curve or bend, diverging from the straight central section. Directly below the interface of the zipper profiles, the wall has a line of weakened tear resistance that can be torn open after the zipper has been opened. A flap portion of the wall, with one of the zipper strips attached to its periphery, can then be folded back to provide a wide opening for accessing the package contents.

Description

BACKGROUND OF THE INVENTION

This invention generally relates to zippers comprising a pair of interlockable strips (e.g., made by extruding plastic material and joined at the ends) for use in reclosable pouches, bags or other packages of the type in which material, such as foodstuff, detergent, etc., may be stored.

Reclosable bags are finding ever-growing acceptance as primary packaging, particularly as packaging for foodstuffs such as cereal, fresh vegetables, snacks and the like. Such bags provide the consumer with the ability to readily store, in a closed, if not sealed, package any unused portion of the packaged product even after the package is initially opened.

Reclosable bags typically comprise a zipper assembly installed in the mouth of the bag. Such zipper assemblies typically comprise a pair of interlockable zipper elements that form a closure. The zipper elements can take on various configurations, e.g. interlocking rib and groove elements having so-called male and female profiles, interlocking closure members having hook-shaped or ball-shaped closure profiles, etc. A consumer can gain access to the contents of the bag by opening the zipper and, if tamper-evident means, such as an external header or an internal membrane or peel seal are also present, breaching the tamper-evident means.

In one type of zipper assembly, the zipper comprises a pair of extruded zipper strips having closure profiles for interlockable engagement, pull flanges for disengaging the closure profiles from each other and extension flanges for attaching the walls of the bag or other package to the zipper. In this type, the zipper strips are pressed together to close the zipper.

Due to difficulty in manually aligning the interlockable closure profiles of flexible zipper strips, it is known to provide a slider or clip that cams or pushes incoming (from the reference point of the slider) sections of the closure profiles into interlocking relationship as the slider or clip slides along the zipper in either direction.

It is now also well known to provide zipper assemblies that are both opened and closed by a slider mounted to the zipper. When the slider moves in one direction along the zipper, the incoming section of the zipper is closed; when the slider moves in the opposite direction, the outgoing section of the zipper is opened. In one type of slider-operated zipper assembly, the slider straddles the zipper and has a separating finger at one end that is inserted between the closure profiles to force them apart as the slider is moved along the zipper in an opening direction. The other end of the slider is sufficiently narrow to force the profiles into engagement and close the zipper when the slider is moved along the zipper in a closing direction.

Other types of slider-operated zipper assemblies avoid the use of a separating finger. For example, U.S. Pat. No. 6,047,450 discloses a zipper comprising a pair of mutually interlockable profiled structures, portions of which form a fulcrum about which the closure profiles may be pivoted out of engagement when lower edges of the bases (on the other side of the fulcrum point) are forced towards each other by the sidewalls of the moving slider.

Many existing form-fill-seal (FFS) machines operate on bag making film and do not incorporate equipment for attaching zipper assemblies to the bag making film. However, zipper application machines are available that can be coupled to the FFS machine to provide the zipper application function. In addition, a slider insertion device may be incorporated as part of the zipper application station. However, operators of FFS machines who do not wish to purchase a zipper applicator and a slider inserter require that bag making film with slider-zipper assemblies be available for purchase. This film can then be run through the FFS machine. Although the packager may need to modify his FFS machine to handle bag making film with slider-zipper assemblies attached, including providing clearance for the sliders to pass through the machine, the FFS machine need not be modified to provide equipment that seals the zipper to bag making film.

Reclosable bags are known in which both zipper strips of the zipper assembly are attached to the exterior of the front panel. Such bags can be made on an FFS machine by feeding bag making film with preattached zipper assemblies. The FFS machine need not perform any zipper application step.

One such bag is disclosed in U.S. patent application Ser. No. 10/263,420 entitled “Resealable Packages with Front Panel Slider-Zipper Assembly”. In one embodiment disclosed therein, the zipper is attached to the front wall of the bag receptacle by means of conduction heat sealing. The zipper comprises a short flange heat sealed to the front wall at a first zone of joinder located at a first height, and a long flange heat sealed to the front wall at a second zone of joinder located at a second height lower than the first height, thereby securing the zipper to the bag receptacle along the length of the zipper. To facilitate opening of the package by the consumer, a closed line (e.g., oval shaped) of weakened tear resistance is formed in the section of the front wall that spans the zones of joinder. To stabilize the zipper and provide slider end stops, the zipper ends can be sealed to the front wall.

There is a continuing need for improved reclosable package designs whereby bag making film with preattached zipper assemblies (with or without sliders) can be formed, filled and sealed without the FFS machine needing to perform any zipper application step.

BRIEF DESCRIPTION OF THE INVENTION

The present invention is directed to a reclosable package having a two-dimensional zipper attachment on the exterior of one wall. The zipper comprises a pair of zipper strips that have straight central sections and end sections that curve or bend, diverging from the straight central section. Directly below the interface of the zipper profiles, the wall has a line of weakened tear resistance that can be torn open after the zipper has been opened. A flap portion of the wall, with one of the zipper strips attached to its periphery, can then be folded back to provide a wide opening for accessing the package contents. The invention is also directed to a web of packaging material having such a two-dimensional zipper attachment.

One aspect of the invention is a reclosable package comprising: a receptacle having an interior space and comprising a wall; and a flexible zipper joined to the wall and disposed on the exterior of the receptacle, the zipper comprising first and second zipper strips, the first zipper strip comprising a first closure profile and a first flange having one portion connected to the first closure profile and another portion joined to the wall in a first zone of joinder, and the second zipper strip comprising a second closure profile and a second flange having one portion connected to the second closure profile and another portion joined to the wall in a second zone of joinder, the first and second closure profiles being interlockable with each other, wherein if the portion of the wall to which the zipper is joined were disposed in a generally planar state, a respective lengthwise portion of each of the first and second zipper strips would be curved.

Another aspect of the invention is an article comprising a web of bag making film and a zipper assembly joined thereto, the zipper assembly comprising first and second zipper strips, the first zipper strip comprising a first closure profile and a first flange having one portion connected to the first closure profile and another portion joined to the web in a first zone of joinder, and the second zipper strip comprising a second closure profile and a second flange having one portion connected to the second closure profile and another portion joined to the web in a second zone of joinder, the first and second closure profiles being interlockable with each other, wherein if the portion of the web to which the zipper assembly is joined were disposed in a generally planar state, each of the first and second zipper strips would be curved along at least respective lengthwise portions thereof.

A further aspect of the invention is a reclosable package comprising: a receptacle having an interior space and comprising front and rear walls; a flexible zipper joined to the front wall and disposed on the exterior of the receptacle, the zipper comprising first and second zipper strips, the first zipper strip comprising a first closure profile and a first flange having one portion connected to the first closure profile and another portion joined to the front wall in a first zone of joinder, and the second zipper strip comprising a second closure profile and a second flange having one portion connected to the second closure profile and another portion joined to the front wall in a second zone of joinder, the first and second closure profiles being interlockable with each other; and a slider mounted to the zipper, wherein if the portion of the front wall to which the zipper is joined were disposed in a generally planar state, each of the first and second zipper strips would be curved along at least respective lengthwise portions thereof and the slider would follow a curved path when traversing the curved lengthwise portions.

Other aspects of the invention are disclosed and claimed below.

BRIEF DESCRIPTION OF THE DRAWINGS

FIGS. 1 and 2 are drawings showing isometric view of a reclosable bag having a two-dimensional zipper attachment with a slider in accordance with one embodiment of the invention. FIG. 1 shows the zipper closed; FIG. 2 shows the zipper open.

FIG. 3 is a drawing showing a fragmentary sectional view of a slider-zipper assembly attached to a wall of a reclosable bag in accordance the embodiment shown in FIG. 1.

FIG. 4 is a schematic showing a front view of a reclosable bag having a two-dimensional zipper attachment in accordance with another embodiment of the invention.

Reference will now be made to the drawings in which similar elements in different drawings bear the same reference numerals.

DETAILED DESCRIPTION OF THE INVENTION

A reclosable package having a two-dimensional zipper attachment in accordance with one embodiment of the invention is depicted in FIGS. 1 and 2. The package comprises a receptacle 2 having an interior volume for containing product and a slider-zipper assembly 4 attached to the exterior of the receptacle. In this embodiment, the receptacle 2 comprises a front wall 10 and a rear wall 12 having upper marginal portions joined at a top seam 14 and lower marginal portions joined at a bottom seam 16 by any conventional means, e.g., conduction heat sealing. The front and rear walls are connected by respective gusseted side walls, only one of which is partially visible in FIG. 1 (indicated by numeral 18). The structure of each gusseted side wall is entirely conventional, each gusset comprising a respective pair of gusset panels connected to each other at a central fold, the other side of one gusset panel being connected to the front wall at another fold and the other side of the other gusset panel being connected at a fold to the rear wall. Although not visible in FIGS. 1 and 2, the receptacle further comprises a vertical lap or fin seal that extends down the middle of the rear wall.

The walls and gussets of the receptacle comprise thermoplastic web material or film. The receptacle may be formed of various types of thermoplastic material, such as low-density polyethylene, substantially linear copolymers of ethylene and a C3-C8 alpha-olefin, polypropylene, polyvinylidene chloride, mixtures of two or more of these polymers, or mixtures of one of these polymers with another thermoplastic polymer. The person skilled in the art will recognize that this list of suitable materials is not exhaustive. The preferred thermoplastic materials are polyethylene and polypropylene.

The zipper of the slider-zipper assembly 4 is also made of thermoplastic material. Therefore the preferred method of attaching the slider-zipper assembly 4 to a wall of the receptacle is by conventional conduction heat sealing, whereby the surface of the zipper and/or the wall is softened or melted by application of heat and pressure, the softened or melted material thereafter fusing the zipper and wall together when it solidifies upon cooling. However, it should be appreciated that the scope of the present invention is not limited to applying thermoplastic zippers to thermoplastic web material by heat sealing. If the bag material is a laminate comprising, for example, a metallized thermoplastic film or paper coated with a layer of thermoplastic material, with the layer of metal or paper being disposed on the exterior of the receptacle, then the zipper could be attached (i.e., joined) to that layer by any suitable means, such as an adhesive layer, an adhesive bonding strip and so forth.

Receptacles of the type comprising heat sealable materials can be readily manufactured on a vertical form-fill-seal (VFFS) machine by wrapping a web of packaging film around a fill tube so that the lateral marginal portions of the web are overlapping; joining those overlapping lateral marginal portions to each other to form the aforementioned lap or fin seal; folding diametrally opposed portions of the web inward to form respective side gussets; cross sealing (i.e., in the transverse direction) the gusseted tube to form a bottom of a pocket; filling the pocket with product; cross sealing the gusseted tube along a transverse line at an elevation above the product fill line to close the top of the pocket; and then severing the completed package from the work in process by cutting the gusseted tube at or above the top seal.

The slider-zipper assembly 4 is applied to the web of packaging material before it enters the VFFS machine. As previously discussed, it is advantageous to attach a multiplicity of slider-zipper assemblies to the web at spaced intervals therealong off site, wind the web with attached slider-zipper assemblies on a supply reel, transport the supply reel to the site of the VFFS machine, and then feed a portion of the web with attached slider-zipper assemblies that is paid out from the supply reel. Alternatively, slider-zipper assemblies can be attached in line by a zipper application station disposed upstream of the VFFS machine. In either case, the converter need not modify the VFFS machine to perform any zipper application operation.

The structure of one type of slider-zipper assembly that can be incorporated in the reclosable package depicted in FIGS. 1 and 2 will now be explained with reference to FIG. 3, which is a cross-sectional view taken along a plane that intersects the zipper but not the slider. The zipper comprises a pair of zipper strips 6 and 8 (e.g., of the type disclosed in U.S. Pat. No. 6,047,450). The zipper strip 6 comprises a closure profile 22 and an extension flange 24 having one portion connected to closure profile 22 and another portion joined to one portion of wall 10 in a first zone that extends the full length of the zipper strip 6. The zipper strip 8 comprises a closure profile 26 and an extension flange 28 having one portion connected to closure profile 26 and another portion joined to another portion of wall 10 in a second zone that extends the full length of the zipper strip 8. As shown in FIG. 3, the closure profiles 22 and 26 are mutually interlockable for closing the zipper, and the bottom portions of the extension flanges 24 and 28 are bent outward at substantially right angles so that those bottom portions lie flat against the receptacle wall 10. As explained in more detail below, the zones of zipper-to-wall joinder comprise respective straight sections that run generally parallel to each other and respective curved sections that run generally parallel to (or equidistant from) each other.

The embodiment depicted in FIG. 3 further includes a slider 20 mounted on the zipper to facilitate its opening and closing. To this end, moving the slider 20 toward one end causes opposing sections of the closure profiles 22 and 26 to disengage and moving the slider 20 toward the opposite end brings opposing sections of the closure profiles into engagement. Slider 20 is shaped to straddle the closure profiles. In a straddling slider, the ends of the slider are open to allow the zipper to pass through. Alternatively, a slider having a separating finger or plow may be employed. The slider 20 may be made in multiple parts and welded together or the parts may be constructed to be snapped together. The slider may also be of one-piece construction. The slider can be made using any desired method, such as injection molding. The slider can be molded from any suitable plastic, such as nylon, polypropylene, polystyrene, acetal, polyketone, polybutylene terephthalate, high-density polyethylene, polycarbonate, or ABS.

To facilitate opening of the receptacle after the zipper has been opened, a line of weakened tear resistance (hereinafter “tear line”), indicated by dashed line 30 in FIG. 3, is formed in receptacle wall 10 in the region between the zones of zipper flange-to-wall joinder. The tear line 30 runs parallel to the zones of joinder, so that it also comprises straight and curved sections. The tear line 30 is designed to rupture when the disengaged zipper strips are pulled apart by the consumer. The tear line may be formed by conventional means such as laser scoring or perforating. For example, the tear line 30 may comprise a line of spaced perforations. In cases where the receptacle needs to be hermetically sealed, the line of perforations may be capped by a sealing stripe (not shown in FIG. 3), as taught in U.S. Pat. No. 5,063,639. The sealing stripe may be heat sealed to the receptacle wall 10 in a band-shaped zone that extends on both sides of the perforated line 30. Such a sealing stripe effectively hermetically seals the perforations, while still leaving the line of weakened tear resistance provided by the perforations.

Returning to FIG. 1, the slider-zipper assembly 4 is shown in a closed state. Assuming that the package shown in FIG. 1 is empty and that the front wall 10 is disposed in a substantially planar state, it can be seen that the zipper is not straight from one end to the other, but rather is bent in two places (i.e., curved sections 38 and 40) equidistant from the opposite ends, causing straight portions 34 and 36 to diverge from the central straight zipper portion 32, by an angle that is in the range of 30 to 90 degrees. Bending may be facilitated by heating zipper portions 38 and 40 prior to bending. If necessary, the zipper flanges may be notched or cut in curved portions 38 and 40 to prevent buckling of the flange on the inside of the curved zipper portions and to prevent uplifting of the flange on the outside of the curved zipper portions. The rate of change in the angle of the curved zipper sections must be gradual enough that the slider 20 can make the turn without undue force being applied.

FIG. 2 shows the slider-zipper assembly 4 after the slider 20 has been moved from the zipper fully closed position to the zipper fully opened position. Slider end stops (not depicted in FIGS. 1 and 2) are provided to prevent the slider 20 from sliding off either end of the zipper. In the zipper open state, the majority of the closure profile of zipper strip 6 is disengaged from the closure profile of the zipper strip 8 (except at the slider end stops and at the parked position of the slider depicted in FIG. 2). A two-dimensional area of the receptacle wall 10, having a perimeter joined to the extension flange of the zipper strip 6, forms a flap 42 that can be folded back to reveal a wide opening 44 in the receptacle wall. The consumer can access the contents of the package via opening 44. To reclose the package, the flap 42 is restored to its original position covering the opening 44, thereby aligning the closure profiles of the zipper. Then the zipper is closed by moving the slider 20 from the position shown in FIG. 2 back to the position shown in FIG. 1.

Another embodiment of the invention is depicted in FIG. 4. This embodiment differs from that shown in FIG. 1 in the shape of the zipper. In the embodiment shown in FIG. 4, the zipper has a straight central section 32′ connected at its ends to respective curved end sections 38′ and 40′. Each curved end section 38′, 40′ may be an arc of predetermined radius, in which case the straight central section is tangent to the curved end sections. The angle of the arc is preferably at least 45 degrees, but not greater than 90 degrees. Slider end stops 46 and 48 are formed at the respective terminations of the curved end section 38′, 40′. The slider end stops may consist of projections formed by ultrasonic stomping of the closure profiles of the zipper strips. Alternatively, any other known means of providing slider end stops (e.g., attachment of U-shaped clips) can be used. Since the zipper is disposed outside of the receptacle, the ends of the zipper strips need not be fused together. However, if the slider is of a type having a separating finger, then the ends of the zipper strips could be fused together to form slider end stops.

In accordance with a further aspect of the invention, the two-dimensional zipper attachment may be covered by a cover strip 50 whose periphery is sealed to the front wall 10. The upper and lower boundaries of cover strip 50 are indicated by dashed lines in FIG. 4. The cover strip provides a tamper-evident feature. The cover strip 50 may be provided with an oval-shaped line of weakened tear resistance that defines a removable tear-out section. Removal of the tear-out section gives the consumer access to the zipper.

While the disclosed embodiments are gusseted bags, the concept of the invention also encompasses bags without gussets. In addition, the receptacle may comprise a bottom wall contiguous with the bottom edges of the front and rear walls and the bottom edges of a pair of side walls (optionally gusseted).

Moreover, although the disclosed embodiments incorporate a slider-zipper assembly wherein movement of the slider in one direction opens the zipper and movement of the slider in the opposite direction closes the zipper, the scope of the invention encompasses use of a slider that only closes the zipper when moved in either direction. If the slider only closes the zipper, then other means, such as pull flanges, may be employed to open the zipper. In accordance with further alternatives, the zipper is not actuated by a slider. Instead the zipper has pull flanges that are pulled apart by the consumer for opening whereas the closure profiles can be pressed together using a thumb and a forefinger to close the zipper.

Furthermore, the reclosable packages of the invention are not limited to being manufactured on a VFFS machine. Methods of manufacture could be used wherein the receptacle comprises front and rear panels, the peripheries of which are joined together on four sides to form top, bottom and two side seams. In this case, the two-dimensional zipper is attached to one of the panels. Alternatively, a two-dimensional zipper could be attached to the front wall of a receptacle having a fold at the bottom and seams at the top and two sides.

While the invention has been described with reference to preferred embodiments, it will be understood by those skilled in the art that various changes may be made and equivalents may be substituted for members thereof without departing from the scope of the invention. In addition, many modifications may be made to adapt a particular situation to the teachings of the invention without departing from the essential scope thereof. Therefore it is intended that the invention not be limited to the particular embodiment disclosed as the best mode contemplated for carrying out this invention, but that the invention will include all embodiments falling within the scope of the appended claims.

As used in the claims, the verb “joined” means fused, bonded, sealed, or adhered, whether by application of heat and/or pressure, application of ultrasonic energy, application of a layer of adhesive material or bonding agent, interposition of an adhesive or bonding strip, etc. As used in the claims, the term “wall” is used in a broad sense to include both a discrete piece of packaging material and a portion of a folded piece of packaging material.

Claims

1. A reclosable package comprising: a receptacle having an interior space and comprising a first wall; and a flexible zipper joined to said first wall and disposed on the exterior of said receptacle, said zipper comprising first and second zipper strips, said first zipper strip comprising a first closure profile and a first flange having one portion connected to said first closure profile and another portion joined to said first wall in a first zone of joinder, and said second zipper strip comprising a second closure profile and a second flange having one portion connected to said second closure profile and another portion joined to said first wall in a second zone of joinder, said first and second closure profiles being interlockable with each other, wherein if the portion of said first wall to which said zipper is joined were disposed in a generally planar state, a respective lengthwise portion of each of said first and second zipper strips would be curved.

2. The package as recited in claim 1, wherein said first wall comprises a line of weakened tear resistance disposed between said first and second zones of joinder.

3. The package as recited in claim 2, wherein if said portion of said first wall to which said zipper is joined were disposed in a generally planar state, a first segment of said line of weakened tear resistance would be straight, and second and third segments of said line of weakened tear resistance would diverge from said first segment at opposite ends thereof

4. The package as recited in claim 2, wherein said first wall comprises a flap portion after said zipper has been opened and said line of weakened tear resistance has been torn, said second zipper strip being attached to said flap portion.

5. The package as recited in claim 1, further comprising a slider mounted to said zipper.

6. The package as recited in claim 1, wherein said receptacle further comprises a second wall joined to said first wall in third and fourth zones of joinder respectively disposed at a top and a bottom of said receptacle.

7. The package as recited in claim 6, wherein said receptacle further comprises first and second side gussets, said first gusset comprising a first gusset panel connected to said first wall and a second gusset panel connected to said second wall and to said first gusset panel, and said second gusset comprising a third gusset panel connected to said first wall and a fourth gusset panel connected to said second wall and to said third gusset panel.

8. The package as recited in claim 1, wherein if said portion of said first wall to which said zipper is joined were disposed in a generally planar state, a first lengthwise section of said second closure profile would be straight, and second and third lengthwise sections of said second closure profile would be curved, said second and third lengthwise sections being respectively connected to opposite ends of said first lengthwise section.

9. The package as recited in claim 8, wherein said second flange is notched in said first and second curved lengthwise sections.

10. The package as recited in claim 1, further comprising a header that covers and blocks access to said zipper.

11. An article comprising a web of bag making film and a zipper assembly joined thereto, said zipper assembly comprising first and second zipper strips, said first zipper strip comprising a first closure profile and a first flange having one portion connected to said first closure profile and another portion joined to said web in a first zone of joinder, and said second zipper strip comprising a second closure profile and a second flange having one portion connected to said second closure profile and another portion joined to said web in a second zone of joinder, said first and second closure profiles being interlockable with each other, wherein if the portion of said web to which said zipper assembly is joined were disposed in a generally planar state, each of said first and second zipper strips would be curved along at least respective lengthwise portions thereof.

12. The article as recited in claim 11, wherein said web comprises a line of weakened tear resistance disposed between said first and second zones of joinder.

13. The article as recited in claim 12, wherein if said portion of said web to which said zipper assembly is joined were disposed in a generally planar state, a first segment of said line of weakened tear resistance would be straight, and second and third segments of said line of weakened tear resistance would diverge from said first segment at opposite ends thereof

14. The article as recited in claim 11, wherein if said portion of said web to which said zipper assembly is joined were disposed in a generally planar state, a first lengthwise section of said second closure profile would be straight, and second and third lengthwise sections of said second closure profile would be curved, said second and third lengthwise sections being respectively connected to opposite ends of said first lengthwise section.

15. The article as recited in claim 11, wherein said second flange is notched in said first and second curved lengthwise sections.

16. A reclosable package comprising: a receptacle having an interior space and comprising front and rear walls; a flexible zipper joined to said front wall and disposed on the exterior of said receptacle, said zipper comprising first and second zipper strips, said first zipper strip comprising a first closure profile and a first flange having one portion connected to said first closure profile and another portion joined to said front wall in a first zone of joinder, and said second zipper strip comprising a second closure profile and a second flange having one portion connected to said second closure profile and another portion joined to said front wall in a second zone of joinder, said first and second closure profiles being interlockable with each other; and a slider mounted to said zipper, wherein if the portion of said front wall to which said zipper is joined were disposed in a generally planar state, each of said first and second zipper strips would be curved along at least respective lengthwise portions thereof and said slider would follow a curved path when traversing said curved lengthwise portions.

17. The package as recited in claim 16, further comprising first and second slider end stops disposed at opposing ends of said zipper.

18. The package as recited in claim 17, wherein said first and second slider end stops comprise respective zones where said first and second closure profiles are fused to each other.

19. The package as recited in claim 16, wherein said front wall comprises a line of weakened tear resistance disposed between said first and second zones of joinder.

20. The package as recited in claim 16, wherein if said portion of said front wall to which said zipper is joined were disposed in a generally planar state, a first lengthwise section of said second closure profile would be straight, and second and third lengthwise sections of said second closure profile would be curved, said second and third lengthwise sections being respectively connected to opposite ends of said first lengthwise section.