Buckles – buttons – clasps – etc. – Separable-fastener or required component thereof – Each mating member having similarly shaped – sized – and...
Utility Patent
1999-03-03
2001-01-02
Sakran, Victor N. (Department: 3626)
Buckles, buttons, clasps, etc.
Separable-fastener or required component thereof
Each mating member having similarly shaped, sized, and...
C024S399000, C024S400000, C383S063000
Utility Patent
active
06167597
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to reclosable plastic bags and packages of the type in which food products, such as chips and cereal, and other goods are packaged for sale to consumers. More particularly, the present invention relates to a reclosable zipper strip for use in transverse-zippered reclosable plastic bags made on form-fill-seal (FFS) machines.
2. Description of the Prior Art
The present invention relates to improvements in the package-making art and may be practiced in the manufacture of thermoplastic bags and packages of the kind that may be used for various consumer products, but which are particularly useful for food products which must be kept in moisture and air-tight packages, free from leakage until initially opened for access to the product contents, which packages are then reclosable by zipper means to protect any remainder of the product therein.
The prior art is fairly well-developed, but nevertheless remains susceptible to improvement contributing to increased efficiency and cost effectiveness.
In particular the present invention relates to the area of reclosable packaging known as the transverse zipper. When making a bag having a transverse zipper, the zipper is attached transverse to the longitudinal axis of the material used to make the bag, as opposed to being attached to the material parallel to the longitudinal axis. A method and apparatus for making reclosable plastic bags with a transverse zipper on an FFS machine is disclosed in U.S. Pat. No. 4,909,017.
Prior to the introduction of the transverse zipper to the reclosable packaging field, reclosable plastic bags made on FFS machines were typically made with a continuous longitudinal zipper, i.e. a zipper parallel to the longitudinal axis of the thermoplastic film used to make the bags. However, there are two primary problems with the longitudinal zipper technique. First, there is a problem in attaining satisfactory sealing of the bags against leakage since the transverse, or side, sealing bars of the FFS machine must flatten and seal the zipper at the same time they are sealing the thermoplastic film from which the packages are being made. The difficulty with which this sealing is consistently and successfully achieved is reflected by the high occurrence of leaking packages.
Second, the length of reclosable bags made on FFS machines when the zipper is attached parallel to the longitudinal axis of the thermoplastic film is limited to the diameter of the filling tube of the FFS machine. Thus, generally bags of this type are wider than they are long. While such bags are suitable for certain products where shorter bags are desirable, such as cheese and chicken parts, these bags are not suitable for applications in which longer bags are desirable, for example, chips and other snack foods.
Among the approaches taken to solve these problems has been the substitution of a transverse zipper for the longitudinal zipper. When a transverse zipper is provided, the transverse sealing bars associated with the FFS machine do not flatten the zipper during formation of the top and bottom seals of the package since the transverse sealing bars may seal the zipper to the thermoplastic film transversely thereacross without having to flatten the zipper ends. In addition, when a transverse zipper is used the length of the packages made on the FFS machine can be varied while the width of the zipper remains the same.
The present invention relates to a particular type of zipper strip which may be used in transverse zipper applications, a method for attaching the zipper strip to thermoplastic film, a method for making reclosable packages on an FFS machine using the zipper strip-equipped thermoplastic film, and a reclosable package utilizing the zipper strip.
In typical transverse zipper package making applications, flanged zipper strips are utilized. The zipper strips are sealed to the thermoplastic film via the flanges, thereby preventing damage to the interlocking closure elements which would otherwise occur during sealing. However, the use of flanged zipper has proven problematic in that the flanges tend to peel or delaminate from the thermoplastic film due to peel forces transmitted to the flanges during opening of the bag by the bag user.
Although flangeless zipper is well known in the art, such zippers are unsuitable for use in transverse zipper applications because they are too narrow to ensure proper sealing by inaccurate seal bars and because the sealing of those zippers to thermoplastic film will cause damage and distortion to the interlocking closure elements.
It is therefore an object of the present invention to provide a flangeless zipper strip for use in transverse-zippered reclosable plastic bags which overcomes the aforementioned sealing problems. Another object of the present invention is to provide a method for attaching the flangeless zipper strip to thermoplastic film, which thermoplastic film can later be used on an FFS machine to make reclosable packages. Another object of the present invention is to provide a method for making packages from the flangeless zipper strip-equipped thermoplastic film. Yet another object of the present invention is to provide a package which utilizes the flangeless zipper strip.
SUMMARY OF THE INVENTION
Accordingly, the present invention is, in four aspects, a zipper strip for use with transverse zippered bags; a method for attaching the zipper strip to a continuous supply of thermoplastic film; a method for making reclosable bags on an FFS machine using the zipper strip-equipped thermoplastic film; and a reclosable bag utilizing the zipper strip.
In accordance with the first aspect of the present invention, the zipper strip comprises a male profile and a female profile. The male profile includes a base and at least one male interlocking member extending from the base towards the female profile. Likewise, the female profile includes a base and at least one female interlocking member extending from the base towards the male profile, the male and female interlocking members being engageable with each other to join the male and female profiles together. Both profiles are flangeless and of a sufficient width to ensure accurate sealing by the seal bars.
One or both profiles further includes at least one high compression member engageable with a portion of the other profile which allows both profiles to be sealed to thermoplastic film across the widths of their respective bases without the male and female interlocking members being crushed or distorted by the application of heat and pressure directly behind or closely adjacent to the interlocking members by the seal bars. The peel problem associated with flanged zipper is eliminated since both profiles can be completely sealed to the thermoplastic film across the widths of their respective bases.
In the second aspect of the present invention, thermoplastic film is intermittently paid off a continuous supply of the same and fed into an FFS machine. A length of the interlocked zipper strip is attached to the flat film transverse to its longitudinal axis as it advances in bag-length increments by initially sealing, or tacking, one of the profiles the film. The zipper-equipped film may be rolled up and used on an FFS machine at a later time, or may be fed directly into an FFS machine to make reclosable bags.
In the third aspect of the present invention, the thermoplastic film with the transverse zipper strips attached at bag length intervals is fed into an FFS machine where it is formed into a bag, filled, and sealed. Specifically, the transverse zipper-equipped thermoplastic film is folded over the collar of the FFS machine and wrapped around the filling tube to form a tube. The longitudinal edges of the film are then sealed to form a back seam. The transverse sealing jaws then seal the bottom of the tube to form an open bag. The bag is then filled, if desired. Finally, the transverse sealing jaws seal both profiles to opposing bag walls across the widths of their respective base
Illinois Tool Works Inc.
Pitney Hardin Kipp & Szuch LLP
Sakran Victor N.
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