Flexible laminate structure with integrated one-way valve

A flexible laminate for a package is described that includes an integrated one-way valve that allows gas generated within the package (e.g., carbon dioxide outgas) to be released to the external environment, while at the same time preventing environmental elements from entering the package. The valve is defined by the layers that form the flexible laminate, as opposed to being a separate structure that is attached to the flexible laminate. In particular, first and second cut lines are defined in a valve area of the first and second film layers of the flexible laminate structure in an offset manner. Oil is pattern-applied to one or both film layers in the valve area, and an opposing surface of one or both of the film layers further includes a surface treatment that decreases the amount of surface energy between the film layers to allow the valve to open at the desired pressure.

BACKGROUND

This invention relates to flexible laminate structures for forming flexible packages and containers. In particular, embodiments of the invention describe a flexible laminate structure that includes a one-way valve feature that is integral to the laminate structure and that is configured to allow gas to vent from within the package.

Packages can be used to store various types of products. In some cases, for example, a flexible laminate structure can be used to form a package, such as a bag or a pouch, for holding a product that may, over time, generate gas (e.g., outgas). For example, freshly roasted coffee may have a tendency to outgas carbon dioxide. Other products may also undergo a reaction over time within the package that results in the generation of gas.

At the same time, the products stored in the package may need to be isolated and protected from the ingress of oxygen and/or moisture to promote freshness and shelf-life and to maintain the quality of the contents for as long as possible.

BRIEF SUMMARY

Embodiments of the invention described herein provide improved packages for storing products and associated methods for forming such packages, where the packages are designed to allow gas generated within the package to escape to the external environment (e.g., to minimize or prevent ballooning or other distortions of the package that may be caused by increasing gas pressure within the package) while at the same time minimizing the amount of oxygen and/or moisture that is allowed to enter the package.

In some embodiments, for example, a flexible laminate structure for a package is provided that includes an integrated one-way valve feature. The flexible laminate structure comprises a first film layer and a second film layer laminated to the first film layer via a permanent adhesive that is pattern-applied to at least one of the first or second film layers. The first film layer includes a first cut line and the second film layer includes a second cut line offset from the first cut line. A valve area is defined in the laminate, where the valve area includes the first and second cut lines and is devoid of the permanent adhesive. In addition, the valve area comprises a viscous medium, such as oil, that is pattern-applied to at least one of the first or second film layers and is disposed between the first and second film layers so as to occupy at least a portion of the valve area. An opposing surface of at least one of the first or second film layers further includes a surface treatment configured to decrease an amount of surface energy between the first and second film layers in the valve area.

In some cases, the surface treatment may comprise at least one of a printed ink, a coating, or a texture. The surface treatment of the first or second film layers may be located only in the valve area. Additionally or alternatively, at least one of the first or second film layers may comprise two or more sub-layers. For example, one of the first or second film layers may comprise polyethylene terapthalate (PET) and/or oriented polypropylene (OPP).

In other embodiments, a method of manufacturing a flexible laminate structure for a package is provided that includes an integrated one-way valve feature. The method may include laminating a first film layer to a second film layer via a pattern-printed permanent adhesive that is applied to at least one of the first or second film layers; defining a first cut line in the first film layer; and defining a second cut line in the second film layer, where the first and second cut lines are offset with respect to each other. In addition, the method may include leaving an area of the laminate devoid of the permanent adhesive so as to define a valve area, the valve area including the first and second cut lines. Moreover, a viscous medium, such as oil, may be pattern-applied to at least one of the first or second film layers in the area of the laminate devoid of the permanent adhesive, and a surface treatment may be effected with respect to at least one of the first or second film layers, where the surface treatment is configured to decrease an amount of surface energy between the first and second film layers in the valve area.

The step of effecting a surface treatment with respect to at least one of the first or second film layers may comprise using at least one of a printed ink, a coating, or a texture. In some cases, effecting a surface treatment with respect to at least one of the first or second film layers may include effecting the surface treatment with respect to at least one of the first or second film layers only in the valve area.

At least one of the first or second film layers may comprise two or more sub-layers. For example, one of the first or second film layers may comprise polyethylene terapthalate (PET). Additionally or alternatively, one of the first or second film layers may comprise oriented polypropylene (OPP).

In some cases, at least one of the steps of defining a first cut line in the first film layer or defining a second cut line in the second film layer may comprise defining the cut line using a laser. Moreover, at least one of the steps of defining a first cut line in the first film layer or defining a second cut line in the second film layer may comprise defining the cut line using mechanical scoring.

DETAILED DESCRIPTION OF THE DRAWINGS

Packages can be used to hold a variety of products, including food products and other products that may undergo a reaction over time that generates gas. As an example, fresh roasted coffee has a tendency to outgas (generate carbon dioxide). Other products may release gas over time, as the product ages or is exposed to even minimal levels of oxygen or moisture as may enter the sealed package.

When such products are stored in a sealed container, there is a danger that the gas produced inside the package will build up. As a result, the package can become inflated and bulge outwardly, which may be unsightly and/or deter a customer from purchasing the package. Furthermore, as more and more gas accumulates within the package, the pressure inside the package may rise to the level of bursting the package or affecting one or more of the seals of the package (e.g., before a consumer wishes to open the package).

At the same time, maintaining a good seal on the package is important to protect the contents of the package from the external environment, such as to prevent the ingress of atmospheric gas (e.g., oxygen and water vapor). The goals of allowing gas to escape from the package while at the same time also preventing the unwanted ingress of gas/water vapor into the package are, thus, seemingly diametrically opposed.

Conventional solutions for venting gas produced within an enclosed package include the use of button valves or pressure sensitive valves that are formed separately from the package and are affixed to the package at the time the package is filled. Such solutions, however, are expensive to implement and add complexity to the filling operation to accommodate application of the valves to the packages.

Accordingly, embodiments of the present invention provide a flexible laminate structure for a package that includes an integrated one-way valve feature configured to allow gas generated within the package (e.g., carbon dioxide outgas) to be released to the external environment, while at the same time maintaining the integrity of the package contents by preventing environmental elements from entering the package. Because the valve is integral to the flexible laminate structure (e.g., defined by the layers that form the flexible laminate, as opposed to being a separate structure that is adhered to or otherwise combined with the flexible laminate), the cost of forming a separate valve and modifying the flexible laminate to accommodate attachment of the valve to the package is avoided, thereby reducing the overall cost and complexity of manufacturing and/or filling a package with a one-way valve. Moreover, as the valve is integrated with the flexible laminate, seams and/or attachment locations of the package can be minimized or eliminated, thereby also reducing the potential for leaks.

With reference toFIG. 1, for example, a package5(e.g., a gusseted bag, pouch, or other flexible package) is shown that is designed to hold a product that is prone to off-gassing, such as freshly roasted coffee. The package5may have a first end10, upon which the package might rest when placed on a surface, and a second end12opposite the first end. In some cases, the product contained within the package5may only occupy a portion of the volume of the package, such that part of the inner volume of the package closest to the second end12may be empty. The first end10of the package5may be gusseted to accommodate a greater volume of product within the package and/or to provide a more stable base on which the package can rest. The second end12of the package5may, in some cases, include a seal15, such as a heat seal that is applied to maintain the package contents inside the package and prevent atmospheric gas from entering the package prior to opening of the package.

In some embodiments, the flexible laminate that forms the package5defines a valve area20. For example, the valve area20may be disposed proximate the second end12of the package5, such as in the empty region of the package. In this way, the risk that the package contents will interfere with the operation of the valve20can be minimized.

FIG. 2shows a close-up view of the valve area20of the package5. The valve area20may, in this regard, be defined to include a first cut line25defined in a first film layer35of the laminate and a second cut line30defined in a second film layer40of the laminate. In the view shown inFIG. 2, for example, the first film layer35forms the outer layer of the flexible laminate forming the package5, whereas the second film layer40forms an inner layer of the flexible laminate and is thus underneath the first film layer.

Accordingly, the flexible laminate structure may comprise a first film layer35and a second film layer40. The second film layer40may be laminated to the first film layer via a permanent adhesive50(shown inFIGS. 3 and 4) that is pattern-applied to at least one of the first or second film layers. The first film layer35may thus include the first cut line25, and the second film layer40may include the second cut line30, which is offset from the first cut line25(e.g., is not aligned with the first cut line, but rather is spaced from the first cut line).

A cross-section of the valve area20is shown inFIG. 3in a closed position and inFIG. 4in an open position. With reference toFIGS. 3 and 4, the valve area20includes the first and second cut lines25,30, such that the first and second cut lines are contained within a perimeter22of the valve area20(shown inFIG. 2). The valve area20may, for example be an area of the flexible laminate that is devoid of the permanent adhesive50adhering the first and second film layers35,40to each other. In this way, the perimeter22of the valve area20may be the interface between an area including permanent adhesive50and an area devoid of permanent adhesive.

The valve area20may comprise a viscous medium, such as oil60, that is pattern-applied to at least one of the first or second film layers35,40and is disposed between the first and second film layers so as to occupy at least a portion of the valve area. The oil60may, for example, be silicone oil in some cases. The presence of the oil60may encourage the opposing surfaces of the first and second film layers35,40(e.g., the surface of each film layer that is adjacent to or most proximate the other film layer) to maintain contact with each other (with the oil disposed therebetween) by virtue of the viscosity and/or surface tension of the oil, such that the integrated valve is biased towards the closed position shown inFIG. 3when the pressure inside the package is below a certain threshold pressure. For example, in some embodiments, the volume of oil60disposed between the first and second film layers35,40is selected such that the valve opens when the pressure inside the package just exceeds the atmospheric pressure outside the package. An example of a desirable range of pressures inside the package for moving the first layer35towards the open position shown inFIG. 4is approximately 0.1 psi to approximately 0.8 psi.

In addition, when the atmospheric pressure outside the package is still slightly above the pressure inside the package, the valve should be configured to move from the open position to the closed position shown inFIG. 3so as to seal and prevent gas and/or moisture from entering the package. In some embodiments, the valve is configured such that a desirable range of atmospheric pressures outside the package for moving the first layer35towards the closed position shown inFIG. 3is approximately 0.05 psi to approximately 0.5 psi, but in any case is less than the pressure required inside the package to open the valve.

Moreover, in some embodiments, an opposing surface of at least one of the first or second film layers35,40may further include a surface treatment configured to decrease an amount of surface energy between the first and second film layers in the valve area. The surface energy may be characterized as the amount of energy required to adhere the opposing surfaces of the first and second film layers35,40to each other. Thus, while the addition of the oil60in the valve area20between the opposing surfaces of the first and second film layers35,40serves to increase the surface energy of the interface between the opposing film surfaces, the resulting surface energy may be too great to allow the valve to open (FIG. 4) at the desired pressure level of the package interior. The inclusion of the surface treatment for at least one of the opposing surfaces of the first and second film layers35,40, however, may counteract the increased adhesion force imparted by the oil60, thereby reducing the surface energy to a level that allows the valve to be moved from the closed configuration shown inFIG. 3to the open configuration shown inFIG. 4when a desired level of pressure is achieved within the package.

In some embodiments, for example, the surface treatment may comprise at least one of a printed ink, a coating, or a texture that is applied to one or both of the opposing surfaces of the first and second film layers35,40. The surface treatment (e.g., the printed ink, coating, or texture) may serve to create bumps or ridges70that extend from the surface of the respective film layer35,40that is treated toward the opposing surface of the other film layer. In the depicted example ofFIGS. 3 and 4, for example, the surface treatment has been applied to the opposing surface of the first film layer35, such that the ridges70extend from the first film layer towards the second film layer40.

Accordingly, the surface energy of the interface between the first and second film layers35,40may be decreased due to the reduced contact area between the two film layers. For example, instead of substantially the entire opposing surface of the first film layer35in the valve area contacting substantially the entire opposing surface of the second film layer40in the valve area, in which case the surface energy would be at a maximum, the ridges70created by the surface treatment in some embodiments may reduce the contact area to the sum of the areas over which each of the ridges contacts the corresponding locations of the opposing surface of the respective film layer. The inventors have found that the smaller the contact area, the less energy is required to separate the first and second film layers35,40, and the less internal package pressure is needed to move the valve from the closed configuration ofFIG. 3to the open configuration ofFIG. 4. Accordingly, the type of surface treatment, the number of ridges70created, and/or the amount of inherent separation between the first and second film layers35,40caused by the extension of the ridges70may be selected to achieve a desired surface energy that results in the opening of the valve at the desired package pressure. In addition, the pattern of the ridges70may be selected to further tune the opening and closure of the valve, depending on the requirements of the package. In some cases, the thickness of the surface treatment (e.g., thickness of the coating used), the roughness imparted by the surface treatment (e.g., based on the chemical makeup of the surface treatment), and the location of the surface treatment may also affect the resulting surface energy.

In the depicted embodiments ofFIGS. 3 and 4, the surface treatment of the first or second film layers is located only in the valve area20; however, in other embodiments, the surface treatment (e.g., the ridges70) may extend outside the valve area20. For example, in some cases, the surface treatment may extend along the entire film, or the surface treatment may be applied to an area that is larger than the valve area20. In this way, alignment of the valve area with the location of the surface treatment during lamination of the film layers35,40may be easier to achieve, such as during the manufacturing process.

The flexible laminate structure may include first and second film layers35,40made of various different materials, depending on the particular application (e.g., depending on the type of product stored in the package). The first and/or second film layers35,40may, for example, include a polymer. In some embodiments, for example, one of the first or second film layers35,40may comprise polyethylene terephthalate (PET). In other embodiments, one of the first or second film layers35,40may include oriented polypropylene (OPP). Other materials that may be used for the first or second film layers35,40may include Polyethylene (PE), metal foil (e.g., aluminum), metallized oriented polypropylene (mOPP), metallized polyethylene terephthalate (mPET), and co-polymer polypropylene (CPP), to name a few. Accordingly, typical laminate structures may include, for example, PET/Foil/PE, PET/Foil/PET/PE, PET/mPET/PE, PET/mOPP/PE, OPP/mOPP/PE, PET/PE, OPP/PE, OPP/OPP, OPP, mOPP, PET/CPP, and PET/Foil/CPP.

In this regard, in some cases, the flexible laminate structure described above may be made using a first or second film layer35,40(or both) that includes two or more sub-layers, as shown inFIG. 5. One or both of the first and second film layers35,40may, for example, be a 2-ply film, a 3-ply film, a 4-ply film, or include additional plies, depending on the particular application (e.g., depending on the type of product to be stored in the package), with some example structures as noted above. InFIG. 5, for example, a flexible laminate structure showing the integrated valve in a closed configuration is illustrated that has a single-ply first film layer35and a 3-ply second film layer40. Sub-layers having different characteristics (e.g., different thicknesses, different materials, etc.) may be used in some cases to achieve certain oxygen and/or moisture transmission rates, so as to promote the freshness and/or shelf life of the product stored in the package. For example, the first film layer35may be a single-ply layer of PET, whereas the second film layer40may be a 3-ply film with sub-layers of foil/PET/PE.

Methods of manufacturing a flexible laminate structure for a package including an integrated one-way valve feature are also provided. According to embodiments of the methods, a first film layer may be laminated to a second film layer via a pattern-printed permanent adhesive that is applied to at least one of the first or second film layers, as described above. A first cut line may be defined in the first film layer, and a second cut line may be defined in the second film layer, where the first and second cut lines are offset with respect to each other. The cut lines may be defined in the flexible laminate after the first and second film layers have been laminated to each other, such as by using precision scoring techniques. In this way, the manufacture of the integrated valve is simplified as compared to conventional methods of providing a valve on packaging, in which a separately-formed valve must be attached to the flexible laminate at a predefined location.

In this regard, the first and/or second cut lines may be made in various ways, such as via a laser. As an alternative to the use of lasers for scoring the laminate, the cut lines can be formed in the laminate by mechanical scoring or cutting. For instance, a kiss roll and a backing roll may be used to form a nip through which the laminate is passed. The kiss roll may comprise a rotary cutting die defining a cutting edge that is configured to define the first and/or second cut lines.

As the first and second film layers are laminated to each other, an area of the laminate is left devoid of the permanent adhesive so as to define the valve area. As described above, the first and second cut lines are defined within the valve area, such that the valve area includes the first and second cut lines. In addition, oil may be pattern-applied to at least one of the first or second film layers in the area of the laminate devoid of the permanent adhesive. A surface treatment may be effected with respect to at least one of the first or second film layers, and the surface treatment may be configured to decrease an amount of surface energy between the first and second film layers in the valve area, as described above.

In some cases, effecting a surface treatment with respect to at least one of the first or second film layers may comprise using at least one of a printed ink, a coating, or a texture, such as to form ridges or bumps between opposing surfaces of the first and second film layers. The surface treatment may be effected with respect to at least one of the first or second film layers only in the valve area in some embodiments, whereas in other embodiments the surface treatment may extend outside of the valve area, such as in cases were the surface treatment is effected with respect to substantially the entire opposing surface of a respective film layer.

As described above, the first and second film layers may comprise different materials, such as PET, OPP, or other polymer materials, as well as non-polymer material such as aluminum foil. Moreover, at least one of the first or second film layers may comprise two or more sub-layers, such as in the example depicted inFIG. 5.