ZIPPER FOR RECLOSABLE FLEXIBLE PACKAGE

Description

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to U.S. Provisional Application No. 63/726,028 (filed 27-November-2024), the entire disclosure of which is incorporated herein by reference.

BACKGROUND

Technical Field

The subject matter of the present application relates to zippers for flexible, reclosable packages.

Discussion of Art

There is a desire to manufacture flexible packages (e.g., bags, pouches, etc.) using hydro-soluble materials and repulpable materials to enhance the recyclability and biodegradability of the flexible packages, relative to plastic materials. An advantage of using hydro-soluble (e.g., water soluble) and paper-based flexible packaging is the ease with which it can be recycled through municipal recycling programs and through the repulping process (e.g., the waste paper reclaim stream), eventually being reclaimed in new paper-based products. The repulpable materials can include plant-based cellulose material. The incorporated cellulose is recoverable during the repulping process. The hydro-soluble materials, such as polyvinyl alcohol (PVOH), can dissolve during the repulping process, so the hydro-soluble material does not contribute to reject material as measured by protocols such as the Fiberboard Association (FBA).

Many flexible packages include zippers to enable the packages to be reclosable. The zippers are conventionally made of polyolefins including low density polyethylene (LDPE) or polypropylene (PP). These polyolefin-based zippers are not compatible with paper recycling streams. It has been proposed that the zippers be produced using hydro-soluble resins, such as PVOH-based resins, so the zippers can also dissolve during the repulping process.

One drawback of using hydro-soluble resins in the zippers and/or panels of the flexible packages is that PVOH materials can be overly sensitive to moisture. The sensitivity to moisture can cause the zipper and/or walls of the flexible package to prematurely solubilize while the user is attempting to use the flexible package. For example, moisture from the contents in the package, the user’s fingers, and/or humidity in the air may result in the zipper softening and becoming non-functional because locking elements are too soft and/or dissolved. Furthermore, the opposing profiles or halves of the zipper may fuse together, undesirably permanently sealing the package.

A sealant resin may be applied on the hydro-soluble resin to provide a moisture barrier to prohibits premature solubilization. The sealant resin may include polyethylene (PE) polymer or another polymer with a long hydrocarbon chain. However, there is a compatibility issue between PVOH-based hydro-soluble resins and polyethylene (PE)-based sealant resins. For example, there is a lack of adhesion between the two resins due to the polar nature of PVOH type polymers and the non-polar nature of PE type polymers. Due to this incompatibility, when the PVOH-based resin is co-extruded with the PE-based sealant, the sealant material is prone to peeling away from the PVOH-based resin, damaging the integrity of the flexible package.

SUMMARY

A need exists for a zipper for a reclosable, flexible package that remains functional during ordinary use for the life of the package, but is able to solubilize and release incorporated repulpable materials, such as cellulose fibers, under specific conditions during a repulping process. A need exists for a zipper exhibiting increased repulpability, biodegradability, recyclability, and/or the like.

In one or more embodiments, a zipper assembly is provided for a reclosable flexible package. The zipper assembly includes a first profile and a second profile. The first profile includes at least a first interlocking element, and the second profile includes at least a second interlocking element. The second interlocking element is complementary to the first interlocking element, and is configured to selectively couple to the first interlocking element to close the zipper assembly. A composition of at least the first profile includes a hydro-soluble resin and a sealant resin. The hydro-soluble resin includes polyvinyl alcohol (PVOH), and the sealant resin includes polyethylene (PE).

In one or more embodiments, a method of forming a zipper assembly for a reclosable flexible package is provided. The method includes producing a first profile that includes at least a first interlocking element, and producing a second profile that includes at least a second interlocking element. The second interlocking element is complementary to the first interlocking element, and is configured to selectively couple to the first interlocking element to close the zipper assembly. At least one of producing the first profile or producing the second profile includes forming a composition that includes a hydro-soluble resin and a sealant resin. The hydro-soluble resin includes polyvinyl alcohol (PVOH), and the sealant resin includes polyethylene (PE).

BRIEF DESCRIPTION OF THE DRAWINGS

The inventive subject matter may be understood from reading the following description of non-limiting embodiments, with reference to the attached drawings, wherein below:

FIG. 1 illustrates a front view of reclosable, flexible package according to an embodiment of the present disclosure;

FIG. 2 illustrates a cross-sectional view of a zipper assembly of the flexible package according to an embodiment;

FIG. 3 is a cross-sectional view of a portion of a first profile of the zipper assembly according to multiple embodiments;

FIG. 4 is a cross-sectional view of a portion of the first profile of the zipper assembly according to another embodiment;

FIG. 5 is a flow chart of a method of forming a zipper assembly for a reclosable, flexible package according to an embodiment.

DETAILED DESCRIPTION

Embodiments set forth herein include a zipper assembly for a reclosable, flexible package. The zipper assembly may be composed of a PVOH-based hydro-soluble resin, a PE-based sealant resin, and an adhesion promoter (AP) compound. The AP compound promotes adhesion between the hydro-soluble resin and the sealant resin. The zipper assembly is designed to remain functional despite incidental contact with moisture, and to solubilize under prescribed conditions, such as specific water temperatures and/or pH values. The zipper assembly is designed to solubilize under the prescribed conditions so that the zipper is not a contaminant in the paper recycling stream. Thus, the zipper assembly may function the same as a conventional PE-based zipper, even when exposed to moisture according to ordinary package usage. The zipper assembly may be incorporated into flexible packages composed, at least in part, from a paper-based material that can be recycled in the waste paper reclaim stream. In one or more embodiments, the zipper assembly may include a repulpable material that is recoverable in the recycling and/or repulping process. For example, the zipper assembly may include cellulose fibers that enhance the structural strength and rigidity to the zipper. The cellulose fibers may be blended with the hydro-soluble resin and extruded into profiles.

The zipper assembly includes a first profile and a second profile. Each of the first and second profiles may be formed via an extrusion process. The first profile includes at least a first interlocking element. The second profile includes at least a second interlocking element. The second interlocking element is complementary to the first interlocking element and selectively couples to the first interlocking element to close the zipper assembly, thereby blocking access to the interior cavity of the flexible package.

In the following description and claims, relative or spatial terms such as “front,” “back,” “side,” “top,” “bottom,” “lateral,” “longitudinal,” and the like are only used to distinguish the referenced elements or features with respect to one another and make the language more readily understandable. The terms do not necessarily require particular positions, sizes, or orientations relative to the surrounding environment. Moreover, in the following description and claims, the terms “first,” “second,” and “third,” etc. may be used as labels to distinguish similar elements (e.g., first and second side walls) and are not intended to impose numerical requirements on their objects.

FIG. 1 illustrates a front view of reclosable, flexible package 100 according to an embodiment of the present disclosure. The package 100 includes a front panel (or wall) 102 and a rear panel (or wall) 104. The front panel 102 may be coextensive with the rear panel 104. Each of the front and rear panels 102, 104 may include a first side edge 106, a second side edge 108, a bottom edge 110, and a top edge 111. The front panel 102 may be joined to the rear panel 104 at the respective first side edges 106, the respective second side edges 108, and the respective bottom edges 110. The intersecting areas, or joints, may be heat seals, folds (e.g., if the front and rear panels are continuous), or any suitable joint that is essentially permanent and cannot be opened without damaging the package 100. The top (or upper) edges 111 define a mouth 112, which permits access to an interior cavity of the package 100. The mouth 112 is reclosable via a zipper assembly 120. The zipper assembly 120 is an intermeshable closure member. The zipper assembly 120 may be laterally oriented, so that it has a longer length in the lateral (or width) direction than the vertical direction.

The package 100 optionally includes a slider 121 that is mounted to the panels 102, 104 and/or the zipper assembly 120. The slider 121 is slidable along a lateral length of the top edges 111 and/or zipper assembly 120. The slider 121 is designed to close the zipper assembly 120 when moved in a first direction and to open the zipper assembly 120 when moved in the reverse direction. The slider 121 is optional, so the package 100 may lack the slider 121 in another embodiment.

FIG. 2 illustrates a cross-sectional view of the zipper assembly 120 of the reclosable flexible package 100 according to an embodiment. The cross-section may be taken along line 2-2 in FIG. 1. The front and rear panels 102, 104 of the flexible package 100 are not shown in FIG. 2. The zipper assembly 120 includes a first profile 122 and a second profile 132. The first and second profiles 122, 132 are discrete bodies, that are positioned opposite one another when incorporated into the package 100. The first and second profiles 122, 132 include cooperating interlocking elements. For example, the first profile 122 includes at least a first interlocking element 124, and the second profile 132 includes at least a second interlocking element 134. The second interlocking element 134 is complementary to the first interlocking element 124, and selectively couples to the first interlocking element 124 to close the zipper assembly 120. The first and second interlocking elements 124, 134 may extend the lateral lengths of the first and second profiles 122, 132, respectively. When the first interlocking element 124 of the first profile 122 couples to the second interlocking element 134 of the second profile 132, the zipper assembly 120 closes the mouth 112 of the package 100. In the open state (or position) of the zipper assembly 120, the first interlocking element 124 and the second interlocking elements 134 are uncoupled, so the mouth 112 of the package 100 is open to permit access to the interior cavity of the package 100.

In an example, the first interlocking element 124 is a male element, and the second interlocking element 134 is a female element. For example, the male interlocking element 124 may include a post 125 that terminates in an arrowhead-shaped detent head 126. The female interlocking element 134 may include curved, extending arms 135 that define a channel 136 therebetween. The arms 135 may have detent hooks 137 at the distal ends. The male interlocking element 124 is designed to enter the channel 136 between the extending arms 135. The detent hooks 137 of the extending arms 135 may interact with (e.g., latch onto) the arrowhead-shaped detent head 126 to secure the male interlocking element 124 within the channel 136 of the female interlocking element 134. The zipper assembly 120 is in the closed state (or position) when the male interlocking element 124 is within the channel 136 of the female interlocking element 134. In another example, the first interlocking element 124 of the first profile 122 is a female element, and the second interlocking element 134 of the second profile 132 is a male element.

In an example, the first profile 122 is fixedly attached to the front panel 102, and the second profile 132 is fixedly attached to the rear panel 104. For example, the first profile 122 may be sealed (e.g., bonded) to an interior side of the front panel 102, and the second profile 132 may be sealed to an interior side of the rear panel 104. The interior sides of the front and rear panels 102, 104 may define at least a portion of the interior cavity of the flexible package 100 that holds contents. In another example, the first profile 122 may be bonded to an exterior side of the front panel 102 so that the first profile 122 projects beyond the top edge 111 of the front panel 102. The second profile 132 may be bonded to an exterior side of the rear panel 104 so that the second profile 132 projects beyond the top edge 111 of the rear panel 104. The first and second profiles 122, 132 may couple together above the top edges 111 to seal the mouth 112. The exterior sides of the front and rear panels 102, 104 are opposite the respective interior sides. The first and second profiles 122, 132 may be sealed to the front and rear panels 102, 104, respectively, via a vertical form fill and seal (VFFS) packing line. The profiles 122, 132 may be secures to the panels via heat sealing, lamination, adhesive bonding, coextrusion, and/or the like. The repulpable, re-closeable flexible package 100 has the advantage of being fully repulpable while offering the consumer unlimited flexibility to determine or alter the contents of the flexible package or vary the amounts of ingredients contained therein.

In another example, the first profile 122 may include multiple first interlocking elements 124, and the second profile 132 may include multiple second interlocking elements 134. Each of the first interlocking elements 124 may couple to a different corresponding one of the second interlocking elements 134.

In an embodiment, the first profile 122 includes a first mounting flange 128, and the second profile 132 includes a second mounting flange 138. The mounting flanges 128, 138 are used to secure the profiles 122, 132 to the front panel 102 or the front and rear panels 102, 104 of the flexible package 100. The first interlocking element 124 projects from the first mounting flange 128. The second interlocking element 134 projects from the second mounting flange 138. When installed in the flexible package 100, an inner surface 129 of the first mounting flange 128 faces towards an inner surface 139 of the second mounting flange 138. The first interlocking element 124 extends from the inner surface 129 towards the second interlocking element 134. The second interlocking element 134 extends from the inner surface 139 towards the first interlocking element 124. The mounting flanges 128, 138 have thicknesses that extend from the inner surfaces 129, 139 to respective outer surfaces 130, 140. The mounting flanges 128, 138 are relatively thin and extend the height of the profiles 122, 132.

The zipper assembly 120 can be installed on different types of reclosable, flexible packages. For example, the zipper assembly 120 may be installed on a flexible package that includes a bottom panel (or wall) extending from the bottom edge 110 of the front panel 102 to the bottom edge 110 of the rear panel 104. The flexible package can include side panels (or wall) that connect the first side edges 106 and the second side edges 108 of the front and rear panels 102, 104. In another example, the zipper assembly 120 may be installed only on the front panel 102, and may be discrete and spaced apart from the rear panel 104. For example, the front panel 102 may define a front access slot that is below the top edge 111. The zipper assembly 102 may be secured to the front panel 102 to selectively close the front access slot. For example, the first profile 122 may be mounted to an upper portion of the front panel 102 above the front access slot, and the second profile 132 may be mounted to a lower portion of the front panel 102 below the front access slot. Example flexible packages with bottom and side walls and front access slots are described in U.S. Patent Application No. 17/936,558, entitled Child-Resistant Front-Opening Recloseable Enclosure, which is incorporated by reference herein in its entirety.

In an embodiment, one or both of the first and second profiles 122, 132 has a composition that includes a hydro-soluble resin, a sealant resin, and an adhesion promoter (AP) compound. The AP compound promotes adhesion between the hydro-soluble resin and the sealant resin. The composition that includes at least the hydro-soluble resin, the sealant resin, and the AP compound is referred to herein as a zipper composition. The zipper composition is designed to be recyclable, such as repulpable, biodegradable, and/or dissolvable. In an example, the zipper composition also includes a repulpable material. In an example, both the first profile 122 and the second profile 132 have the zipper composition, meaning that both profiles 122, 132 have the same material composition. Forming both profiles 122, 132 to have the same composition simplifies the manufacturing process and reduces waste. In another example, only the first profile 122 has the zipper composition described herein. The second profile 132 has a different composition, such as a composition that is mostly polyolefins. In yet another example, the second profile 132 has the zipper composition, but the first profile 122 has a different composition.

The zipper composition includes a hydro-soluble resin which is a polymer material that is dissolvable in water or other aqueous liquids. Suitable hydro-soluble polymers include without limitation alkali-soluble polyvinyl acetate copolymers, ethylene-maleic anhydride copolymers, polyacrylates, polyethers, polyvinyl alcohol (PVOH), ethylene vinyl alcohol, polyvinyl pyrrolidone, polyacrylamides, styrene-maleic anhydride, water-soluble cellulosic ethers, hydroxyethylcellulose, methycellulose, sodium carboxymethylcellulose, and combinations thereof. In an embodiment, the hydro-soluble resin includes at least PVOH.

In an example, the hydro-soluble resin may be PVOH with one or more additives. The one or more additives may include a polyethylene (PE) wax material. The PE wax material may assist with tailoring the properties of the hydro-soluble resin to desired packaging applications and conditions. The PE wax may reduce the solubility of the PVOH, allowing the zipper to withstand some exposure to moisture during the ordinary use of the flexible package 100. For example, the hydro-soluble resin may be selected so that the zipper assembly 120 functions like a normal polyethylene zipper when exposed to moisture under typical package usage. The hydro-soluble resin may permit the zipper assembly 120 to solubilize after an extended time period and/or under specific recycling conditions (high water temperature, high or low pH), so that the hydro-soluble resin is not a contaminant in the paper recycling stream. One hydro-soluble resin that can be used in the zipper composition is the copolymer composition described in U.S. Patent 10,947,332, entitled Copolymer With Programmable Water Solubility, which is incorporated by reference herein in its entirety.

In an example, the hydro-soluble resin of the zipper composition may include a repulpable material. The repulpable material may be blended in with the hydro-soluble resin. The repulpable material may provide structural strength and rigidity to the zipper assembly 120. After the usable life of the flexible package 100, the repulpable material may be recoverable in the recycling (e.g., repulping) process. The term “repulpable” refers to paper or another sheet material that can be converted back into dissociated pulp or fibers for possible recycling. For the zipper assembly 120, suitable repulpable materials include plant-based cellulose materials (e.g., cellulose fibers). The suitable plant-based cellulose materials include without limitation wood pulp, paper fibers, cotton, linen, silk, wool, and combinations thereof. Combining the plant-based cellulose material with the hydro-soluble resin may provide mechanical and structural integrity necessary to form the functional zipper assembly 120. In an example, the repulpable material is cellulose fibers. In an alternative embodiment, the zipper composition does not include the repulpable material.

The sealant resin is a polymer material. The sealant resin may include polyethylene (PE). In an example, the PE is linear low density polyethylene metallocene (mLLDPE). The PE is non-polar, so does not bond well with the non-polar nature of the hydro-soluble resin. For example, the PVOH or other alcohol in the hydro-soluble resin is non-polar.

The AP compound promotes adhesion between the sealant resin and the hydro-soluble resin. The AP compound may be a functionalized PE material. The AP compound in an example is a polyethylenimine (PEI). More specifically, the AP compound may be a branched polymeric amine. In an example, the AP compound is a multi-functional cationic polyethyleneimine (PEI) with a branched polymer structure. The branched PEI has have both polar and non-polar groups. The polar portion of the AP compound bonds to the PVOH or other alcohol of the hydro-soluble resin. The non-polar portion of the AP compound bonds to the non-polar PE of the sealant resin. The AP compound prohibits the sealant from separating from the PVOH-based body (or base) of the zipper profile. In an example, the AP compound is a polymeric amine. The polymeric amine includes an amine functional group that bonds to the PVOH of the hydro-soluble resin and a hydrocarbon functional group that bonds to the PE of the sealant resin. One suitable example of the AP compound is Lupasol® P, manufactured by BASF.

In an embodiment, the entire body of the first profile 122 of the zipper assembly 120 has the zipper composition described above. For example, both the first interlocking element 124 and the first mounting flange 128 have the zipper composition. Furthermore, the entire body of the second profile 132, including both the second interlocking element 134 and the second mounting flange 138, may have the zipper composition. In an example, the first profile 122 and the second profile 132 are formed by respective extrusion processes.

The zipper assembly 120 is mounted to one or more panels (e.g., panels 102, 104) of the flexible package 100 to render the package 100 reclosable. The panels of the flexible package 100 may be composed of hydro-soluble polymers and/or repulpable materials (e.g., plant-based cellulose materials). By forming the panels of hydro-soluble polymers and/or repulpable materials, the entire flexible package 100 may be recycled (e.g., repulped, dissolved, biodegraded, etc.) after the usable life of the package 100. The flexible package 100 may replace disposable non-repulpable plastic packages. The flexible package 100 may be more environmentally friendly than conventional disposable non-repulpable plastic packages.

FIG. 3 is a cross-sectional view of a portion of the first profile 122 of the zipper assembly 120 according to multiple embodiments. The first profile 122 includes a base 200 and a coating layer 202. The base 200 is unitary (e.g., one-piece) and forms the first interlocking element 124 and the first mounting flange 128. For example, the first interlocking element 124 is an integral (e.g., seamless) extension of the first mounting flange 128. The coating layer 202 is applied on an outer surface 204 of the base 200 along the first mounting flange 128. The first interlocking element 124 projects from an inner surface 206 of the base 200, opposite the outer surface 204. The outer surface 204 of the base 200 defines the outer surface 130 of the first mounting flange 128 until the coating layer 202 is applied. Once applied, the coating layer 202 defines the outer surface 130.

The first profile 122 has the zipper composition described above. In a first embodiment, the base 200 is a mixture of the hydro-soluble resin and the AP compound. The coating layer 202 is the sealant resin. The AP compound within the base 200 promotes adhesion/bonding of the sealant resin (coating layer 202) to the hydro-soluble resin (base 200). In an example, the base 200 may be formed by blending the hydro-soluble resin and the AP compound to form a first mixture. The first mixture is then extruded in the shape of the base 200 (e.g., the shape of the first profile 122 shown in FIG. 2). After cooling the base 200, the sealant resin is then applied to one or more surfaces of the base 200 to form the coating layer 202. The sealant resin may be applied via spray coating, dipping, co-extrusion, and/or the like. In the example in which the sealant resin is co-extruded, the first mixture may be supplied by one melt path manifold of a die, and the sealant resin may be supplied in another melt path manifold of the die so that the two layers (e.g., base layer and coating layer) are concurrently extruded in contact with each other. Although the coating layer 202 is only shown on the outer surface 204 of the base 200 in FIG. 3, the coating layer 202 may be present on different surfaces and/or more surfaces of the base 200 in other examples. For example, the coating sealant in another example may cover the full surface area of the base 200, completely surrounding the base 200 with the coating layer 202.

In a second embodiment, the hydro-soluble resin is extruded by itself to form the base 200 shown in FIG. 3. For example, the AP compound is not mixed with the hydro-soluble resin and is not present in the base 200. The AP compound may be mixed with the sealant resin to form a second mixture. The second mixture may be applied on one or more surfaces of the base 200 to form the coating layer 202. The AP compound in the second mixture may promote adhesion/bonding of the sealant resin (coating layer 202) to the hydro-soluble resin (base 200). The second mixture may be applied on the base 200 by spraying, dipping, co-extruding, and/or the like. In the co-extrusion example, the second mixture (including the blend of the sealant resin and the AP compound) may be supplied by one melt path manifold of a die, and the hydro-soluble resin may be supplied in another melt path manifold of the die so that the two layers (e.g., base layer and coating layer) are concurrently extruded in contact with one other. The coating layer 202 may be formed with one or more adhesive resins, such as an anhydride-modified ethylene vinyl acetate polymer, an anhydride modified LLDPE-based resin, or the like. These adhesive resins can bond with polyethylene-based resins, polyamides, EVOH, ionomeric resins, or the like.

With respect to extruding or co-extruding the base 200, a filler can be blended into the resin of the base 200 to allow the extruding speed to be increased and/or the draw down width of the resultant profile 122 and/or 132 to be reduced (relative to the base 200 not including the filler, having a different filler, or having a different amount of the same filler). For example, blending in calcium carbonate with the resin forming the base 200 (such that the resin includes approximately 30%, or exactly 30%, filler by weight) can increase how quickly the base 200 can be extruded out of the extrusion die. For example, the extrusion can occur four times faster, such as eighty feet per minute instead of twenty feet per minute without the filler. The term “approximately” can include a range of values outside of the stated value, such as within manufacturing tolerances, within a significant digit, within 5%, within 3%, or within 1% in different examples. Additionally, the extruded base 200 may be stronger with the filler such that the extruded base 200 can be pulled, or drawn down, faster than without the filler. Increasing the draw down of the extruded base 200 can allow for the width (e.g., measured in directions extending perpendicularly into and out of the plane of FIG. 2) to be reduced, such as to no wider than ten millimeters. These relatively narrow profiles 122, 132 can be desired as they can consume less space than wider profiles 122, 132.

FIG. 4 is a cross-sectional view of a portion of the first profile 122 of the zipper assembly 120 according to another embodiment. The first profile 122 includes a base portion 200 and a coating layer 202, similar to FIG. 3. The first profile 122 in FIG. 4 also has an intermediate layer 210 between the base 200 and the coating layer 202. In the illustrated embodiment, the first profile 122 is a stack of at least three layers having different material compositions. The layers are the base 200, the intermediate layer 210, and the coating layer 202. In an example, the hydro-soluble resin forms the base 200. The sealant resin forms the coating layer 202, and the AP compound forms the intermediate layer 210. In an example, the intermediate layer 210 is directly between the base 200 and the coating layer 202. For example, the intermediate layer 210 may be applied on one or more surfaces of the base 200, and the coating layer 202 may be applied on one or more surfaces of the intermediate layer 210. As a result, the AP compound may be sandwiched between the hydro-soluble resin and the sealant resin in the composition of the first profile 122. The AP compound in the intermediate layer 210 promotes adhesion/bonding of the sealant resin (coating layer 202) to the hydro-soluble resin (base 200). For example, the hydro-soluble resin may include PVOH, and the sealant resin may include PE, which does not adhere well to PVOH. In FIG. 4, the intermediate layer 210 is applied on the outer surface 204 of the base 200 along the first mounting flange 128. The coating layer 202 is applied on an outer surface 212 of the intermediate layer 210. The coating layer 202 defines the outer surface 130 of the first mounting flange 128.

In an example manufacturing process, the hydro-soluble resin is extruded in the shape of the base 200 of the first profile 122 (e.g., the shape of the first profile 122 shown in FIG. 2). After cooling the base 200, the AP compound is applied on one or more surfaces of the extruded base 200 to form the intermediate layer 210. The AP compound may be applied via spray coating, dipping, co-extrusion, and/or the like. The sealant resin is applied on the AP compound to form the coating layer 202. The sealant resin may be applied via spray coating, dipping, co-extrusion, and/or the like. In an example, the three layers are co-extruded. For example, the hydro-soluble resin may be supplied by one melt path manifold of a die, the AP compound may be supplied by a second melt path manifold of the die, and the sealant resin may be supplied by a third melt path manifold of the die so that the three layers are concurrently extruded in contact with each other in the stacked arrangement shown in FIG. 4. Although the intermediate and coating layers 210, 202 are only shown on the outer surface 204 of the base 200 in FIG. 4, the intermediate and coating layers 210, 202 may be present on different surfaces and/or more surfaces of the base 200 in other examples. For example, the AP compound in another example may cover the full surface area of the base 200, completely surrounding the base 200 with the intermediate layer 210.

Although only the first profile 122 is shown in FIGS. 3 and 4, the second profile 132 of the zipper assembly 120 may be constructed using the same techniques and materials as the first profile 122.

After manufacturing the zipper assembly 120, the first and second profiles 122, 132 may be mounted to one or more panels of the flexible package 100. For example, the profiles 122, 132 may be heat sealed, adhesively bonded, or the like to the wall panels. The wall panels may be constructed, at least in part, of repulpable material, such as plant-based cellulose material. The repulpable material of the wall panels and the zipper assembly 120 may be recoverable via a repulping process. The panels of the flexible package 100 may include a polyolefin polymer, such as a PE coating. The PE coating on the wall panels may bond well to the sealant resin of the coating layer 202 of the zipper profiles 122, 132.

FIG. 5 is a flow chart 300 of a method of forming a zipper assembly for a reclosable, flexible package according to an embodiment. The method may be used to form the zipper assembly 120 shown in FIGS. 1 through 4. In other examples, the method may include additional steps not shown in FIG. 5, a different arrangement or order of the steps shown in FIG. 5, and/or may omit one or more of the steps shown in FIG. 5.

At step 302, a first profile 122 is produced that includes at least a first interlocking element 124. The first profile 122 may include a mounting flange 128 from which the first interlocking element 124 projects. The first profile 122 is produced to have a composition that includes a hydro-soluble resin, a sealant resin, and an adhesion promoter (AP) compound. The hydro-soluble resin includes polyvinyl alcohol (PVOH), and the sealant resin includes polyethylene (PE). The AP compound promotes adhesion between the hydro-soluble resin and the sealant resin. Optionally, the composition of the first profile 122 may also include a plant-based cellulose material. The AP compound may include branched polyethylenimine (PEI).

Steps 304 and 306 describe the production of the first profile 122 at step 302. At step 304, a base 200 (e.g., base portion) is extruded to include the mounting flange 128 and the first interlocking element 124 projecting from the mounting flange 128. The base 200 includes at least the hydro-soluble resin.

At step 306, a layer is applied on at least one surface of the base 200. The layer includes at least one of the AP compound or the sealant resin. In a first example, the layer is a coating layer 202 that includes the sealant resin without including the AP compound. The AP compound may be mixed with the hydro-soluble resin and present in the base 200. In a second example, the layer is a coating layer 202 that includes a mixture of the AP compound and the sealant resin. The method may include mixing the AP compound and the sealant resin to form the mixture prior to applying the coating layer 202 on the at least one surface of the base 200. In a third example, the layer is an intermediate layer 210 that includes the AP compound therein. The method may include applying a coating layer 202 on a surface of the intermediate layer 210. The coating layer 202 includes the sealant resin. As such, the AP compound in the intermediate layer 210 is sandwiched between the base 200 (including the PVOH-based hydro-soluble resin) and the coating layer 202 (including the PE-based sealant resin). In all examples, the AP compound promotes adhesion between the hydro-soluble resin and the sealant resin.

At step 308, a second profile 132 is produced that includes at least a second interlocking element 134. The second interlocking element 134 is complementary to the first interlocking element 124 and is configured to selectively couple to the first interlocking element 124 to close the zipper assembly 120. The second profile 132 may be produced in the same or a similar process as the first profile 122. The second profile 132 may have the same composition as the first profile 122. Alternatively, the second profile 132 may have a different composition than the first profile 122.

At step 310, the first profile 122 and the second profile 132 are secured to one or more panels 102, 104 of a flexible package 100 to permit the zipper assembly 120 to selectively close a mouth 112 of the flexible package 100. In an example, the first profile 122 is secured to a front panel 102, and the second profile 132 is secured to a rear panel 104. In another example, both profiles 122, 132 are secured to the same panel 102.

It is to be understood that the above description is intended to be illustrative, and not restrictive. For example, the above-described embodiments (and/or aspects thereof) may be used in combination with each other. In addition, many modifications may be made to adapt a particular situation or material to the teachings of the inventive subject matter without departing from its scope. While the dimensions and types of materials described herein are intended to define the parameters of the inventive subject matter, they are by no means limiting and are example embodiments. Many other embodiments will be apparent to one of ordinary skill in the art upon reviewing the above description. The scope of the inventive subject matter should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. In the appended claims, the terms “including” and “in which” are used as the plain-English equivalents of the respective terms “comprising” and “wherein.” Further, the limitations of the following claims are not written in means-plus-function format and are not intended to be interpreted based on 35 U.S.C. § 112(f), unless and until such claim limitations expressly use the phrase “means for” followed by a statement of function void of further structure.

This written description uses examples to disclose several embodiments of the inventive subject matter and also to enable one of ordinary skill in the art to practice the embodiments of inventive subject matter, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the inventive subject matter is defined by the claims, and may include other examples that occur to one of ordinary skill in the art. Such other examples are intended to be within the scope of the claims if they have structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal languages of the claims.

As used herein, an element or step recited in the singular and proceeded with the word “a” or “an” should be understood as not excluding plural of said elements or steps, unless such exclusion is explicitly stated. Furthermore, references to “one embodiment” of the present inventive subject matter are not intended to be interpreted as excluding the existence of additional embodiments that also incorporate the recited features. Moreover, unless explicitly stated to the contrary, embodiments “comprising,” “including,” or “having” an element or a plurality of elements having a particular property may include additional such elements not having that property.