Patent Application
20090042706
1. Field of the Invention
The present invention pertains to a method and apparatus for applying hot-melt adhesive to zipper flanges and for subsequently applying the zipper to reclosable packages.
2. Description of the Prior Art
In the prior art, reclosable packages and the methods of manufacture thereof, are well-developed and generally satisfactory for their intended purposes. Moreover, the manufacturing methods of larger reclosable packages, that is, of the size typical for charcoal, animal feed, and similar products, have been developed in commonly assigned U.S. patent application Ser. No. 11/728,477 entitled “High Burst Zipper Assembly for Large Reclosable Packages”; U.S. patent application Ser. No. 11/728,405 entitled “Method of Producing High Burst Zipper Assemblies for Large Reclosable Packages” and application Ser. No. 11/728,413 entitled “Hot-melt Adhesive Systems for Zipper Assemblies on Large Bag Constructions of Various Substrates”, all filed on Mar. 26, 2007.
However, further improvements are always sought, particularly with respect to a range of package sizes, including those between the typical grocery-sized smaller reclosable packages and the above-described larger reclosable packages.
It is therefore an object of the present invention to provide improvements for reclosable packages and the methods of manufacture thereof.
It is therefore a further object of the present invention to provide these improvements for a range of sizes of reclosable packages.
These and other objects are attained by providing an apparatus and method wherein the zipper is unreeled from a spool with the two flanges together. The interlocking elements of the zipper are captured between a pair of grooved rollers while two sets of pinch rollers separate or spread the two flanges. The zipper, including the separated flanges, is passed over a roller with the interior walls of the flanges facing upwardly. A hot-melt applicator is located over the roller and sprays the hot-melt adhesive downwardly on the interior walls of the zipper flanges. The zipper is then guided over the top of the reclosable package by a tube with a slot cut down its full length. Guides, either with or without vacuum, are used to position the package between the zipper flanges. A wedge guide is then used to lay the zipper flanges to both sides of the horizontally oriented reclosable package. Thereafter, driven pressure belts are used to create highly desirable and uniform surface contact between the zipper flanges, hot-melt adhesive and the reclosable package.
This method is particularly applicable to large reclosable packages made with multi-wall or propylene material. However, this method may be applied to other sizes of reclosable packages, made from different materials.
Further objects and advantages of the invention will become apparent from the following description and from the accompanying drawings and claims, wherein:
Referring now to the drawings in detail, wherein like numerals indicate like elements throughout the several views, one sees that
The zipper 100 is provided as a continuous length of zipper material traveling in the machine direction, at a selected speed, from a spool 200 (not drawn to scale), typically with the first and second interlocking elements 102, 104 of the respective first and second zipper profiles 110, 112 interlocked with each other and with first and second flanges 106, 108 of the respective first and second zipper profiles 110, 112 abutting each other. Spool 200 is unreeled to provide the zipper 100 in the machine direction.
As further shown in
First pair of opposed pinch rollers 204, 206 and profile guide roller 212 are mounted on first position adjustment device 216 to adjust and vary the desired position, orientation and alignment of the pinch rollers 204, 206 and profile guide roller 212. Likewise, second pair of opposed pinch rollers 208, 210 and the second (unillustrated) profile guide roller are mounted on second position adjustment device 218 to adjust and vary the desired position, orientation and alignment of the pinch rollers 208, 210 and second (unillustrated) profile guide roller.
Zipper 100, with first and second flanges 106, 108 separated and the interior walls thereof facing upwardly, passes over roller 220 (which may be grooved in order to align the zipper 100) and thereafter passes under hot-melt applicator 222 which sprays hot-melt adhesive downwardly onto the upwardly facing interior walls of first and second flanges 106, 108. The downward spraying of the hot-melt adhesive is envisioned to increase the long-term performance of the nozzle of the hot-melt applicator 222.
It is envisioned that hot-melt applicator 222 could apply any number of hot-melt adhesives, such as would be known to those skilled in the art upon review of this disclosure. However, it is particularly envisioned that hot-melt adhesives such as hot-melt, cross-linkable adhesive (such as hot-melt cross-linkable polyurethane reactive adhesive) would be particularly adapted to this method and apparatus, particularly for larger packages or bags with multi-layer paper or woven polypropylene walls.
Zipper 100, with the hot-melt adhesive applied as described above, passes to guide tube 224. Guide tube 224 includes a tubular interior which captures the interlocked first and second interlocking elements 102, 104 and further includes a longitudinal slot 226 which guides first and second flanges 106, 108 back together and directs the first and second flanges 106, 108 in a direction toward the package 300, thereby capturing the edge 302 of one of series of horizontally oriented packages 300 that are moving (typically continuously) in the machine direction at a speed equal to that of zipper 100. Edge 302 includes an opening or mouth between two walls of material, such as multi-layer paper or woven polypropylene. Edge 302 will form the top of the finished reclosable package, with zipper 100 providing the reclosable characteristics of the mouth thereof. First flange 106 is urged against the top wall (with respect to the horizontal orientation of the package 300 illustrated in
Longitudinal slot 226 may have a width which gradually tapers in order to urge the first and second flanges 106, 108 together smoothly, while decreasing the risk of snagging. Guide tube 224 is mounted on third position adjustment device 230 in order to vary the position, orientation and alignment of guide tube 224. Guides (not shown), with or without vacuum, may be used to position package 300 between the first and second zipper flanges 106, 108.
Zipper 100, along with the packages or bags 300 attached thereto, continues to move in the machine direction at the selected velocity so that first and second flanges 106, 108, with edge 302 of package or bag 300 captured therebetween, is introduced to driven-belt apparatus 400 which is illustrated, in part, in the upper right hand corner of
Driven-belt apparatus 400 includes upper and lower forward opposed rollers 402, 404 and upper and lower rearward opposed rollers 406, 408. Driven-belt apparatus 400 further includes wedge guides 401 (see
Piston arrangement 422, shown in
It is envisioned that this apparatus is particularly well-adapted for continuous operation (that is, typically without the need for intermittent movement) through a range of operating speeds.
Thus the several aforementioned objects and advantages are most effectively attained. Although preferred embodiments of the invention have been disclosed and described in detail herein, it should be understood that this invention is in no sense limited thereby and its scope is to be determined by that of the appended claims.
