Patent Application
20110293204
1. Field of the Disclosed Embodiments
The invention is directed to a reclosable zipper with zipper profiles that comprise compressible foamed sealant layers for enhancing the connection with packaging films, and wherein the zipper has interlocking elements which are unfoamed.
2. Description of the Related Art
Zippers are typically sealed to a packaging film by compressing the zipper, or a portion of the zipper, between layers of film by two heated seal bars. For this system to work, the sealing surfaces and alignment of the seal bars must be maintained to very tight tolerances, which are often not the case in many packaging operations, resulting in weak or spotty seals.
One option is to enhance the connection between the reclosable zipper and the package film with a sealant. This is because sealants provide stronger zipper to film seals at a lower temperature, pressure and/or dwell. However, typical relatively incompressible sealant layers result in either weak spots in the seal or spots where seal bars burn through the packaging film, which results in weak spots in the package.
In view of the problems with typical sealants, a compressible foamed sealant layer is an option for enhancing the connection between the reclosable zipper and the package film. The compressibility of the foamed sealant layer provides a more consistent zipper to package film seal. For example, the durometer of the foamed sealant layer can be selected so that the foamed sealant layer collapses in areas of high spots when a seal bar presses against the zipper and packaging film, allowing the low spots in the seal bar to contact the zipper and film with adequate pressure to form a proper seal. In addition, maintenance of a packaging machine is much less critical with a foamed sealant layer. Another advantage is that foamed sealant layers act as insulating layers, reducing the likelihood that the inside surfaces of the zipper profile flanges will seal to each other when the zipper is sealed to the package. In addition, there is a reduced likelihood that the flanges will seal together where no intervening barrier is provided. Yet another advantage of utilizing foamed sealant layers is that less plastic can be used to make the zipper, so that the zipper weighs less, improving sustainability from a materials point as well as a shipping aspect.
An example of an application of foamed material for manufacturing a zipper is provided in U.S. Pat. No. 5,520,463 to Tilman. Tilman discloses a zipper that is either completely foamed, or has a foamed core encapsulated within a solid skin layer or casing of polymeric resin material to which no blowing agent has been added. That is, in Tilman, the profiles, including the interlocking elements, are extruded from a synthetic polymeric resin material such as low-density polyethylene (LDPE). The resin material is mixed with a blowing agent, such as HYDROCEROL® CF 40 E, included in an amount less than or equal to 5% of the synthetic polymeric resin material by volume. The blowing agent provides the resin with a fine-celled foam structure, increasing the size (cross-sectional area) of the profiles without increasing the mass of the zipper at opposing side seals. However, the foamed interlocking elements taught in Tilman fail to provide required rigidity. The lack of rigidity of the interlocking elements of such zippers results inadequate strength to remain closed when product is in the package.
A reclosable zipper is disclosed which includes a first profile which comprises a first compressible foamed sealant layer, and a first interlocking element, which is unfoamed, extending from the first profile. The zipper includes a second profile which comprises a second compressible foamed sealant layer, and a second interlocking element, which is unfoamed, extending from the second profile. The rigidity of the interlocking elements provides the required stability when the zipper is closed while the foamed sealant layers improve the sealing characteristics of the zipper to a packaging film.
The accompanying figures illustrate the disclosed embodiments, which are to be considered as examples only, and in which:
Turning to
As illustrated in the figures, the first interlocking element 16 is a female zipper element and the second interlocking element 22 is a male zipper element, and the first profile 12 is as large in a bag height-wise direction as the second profile 18. The foamed sealant layers 14, comprise the same foamed sealant. Specifically, for example, the foamed sealant layers 14, comprise a foamed polyofin sealant resin. Most polyolefin sealant resins can be foamed using commercially available foaming agents that react when heated in a barrel of an extruder. The interlocking elements 16, 22 comprise polyolefin sealant resin which is unfoamed. The resins used in the sealant layers may include, but are not limited to mLLDPE, particularly mLLDPE's with densities less than 0.910, co-polymers, and lower melting point resins. In addition, the sealant layer could be made from a similar resin as the interlocking elements, only foamed.
The first profile 12 comprises a first product side flange 24, a first consumer side flange 26, and a first connecting flange 28 from which the first interlocking element 16 extends, where the first connecting flange 28 is between, in a bag height-wise direction, the first product side flange 24 and the first consumer side flange 26. The second profile 18 comprises a second product side flange 30, a second consumer side flange 32, and a second connecting flange 34 from which the second interlocking element 22 extends, where the second connecting flange 34 is between, in a bag height-wise direction, the second product side flange 30 and the second consumer side flange 32.
In the embodiments illustrated in
More specifically, in the embodiment illustrated in
In the embodiment illustrated in
In the embodiment illustrated in
In the embodiment illustrated in
A bag is within the scope of the disclosed embodiments which comprises any of the above disclosed reclosable zippers. As illustrated in
As illustrated in
In sum, what has been disclosed is a zipper 10 for a reclosable package which has compressible sealant layers 14, 20 for improving the sealing characteristics between the zipper 10 and packaging film. The foamed sealant layers 14, 20 can be localized, extruded as sealing ribs and extended in a bag width-wise direction across the backside of the profiles 12, 18. Alternately the profile flanges can be entirely formed from a foamed sealant, or can be partially formed from a foamed sealant with portions 28, 34 of respective profiles 12, 18, which support respective interlocking elements 16, 22, being left solid.
The present disclosed embodiments elements may be configured in other specific forms without departing from the spirit or essential characteristics identified herein. The described embodiments are in all respects only as illustrative and not as restrictive. The scope of the embodiments is, therefore, indicated by the appended claims and their combination in whole or in part rather than by the foregoing description. All changes that come within the meaning and range of equivalency of the claims are to be embraced within their scope.
This application claims priority to U.S. Provisional Patent Application No. 61/298,977, to Plourde, filed on Jan. 28, 2010, the disclose of which is incorporated herein by reference in its entirety.
| Number | Date | Country | |
|---|---|---|---|
| 61298977 | Jan 2010 | US |
