Flexible bags – With closure – Including closure flap which overlaps sidewall exterior when...
Reexamination Certificate
2000-06-08
2002-04-09
Pascua, Jes F. (Department: 3727)
Flexible bags
With closure
Including closure flap which overlaps sidewall exterior when...
C383S109000, C383S120000
Reexamination Certificate
active
06367976
ABSTRACT:
FIELD OF THE INVENTION
The invention is directed to gusseted large pinch-closure type multi-wall bags requiring side gussets from 5½-6″ and larger.
BACKGROUND OF THE INVENTION
Gusseted bags, having top and bottom pinch closeable ends, are typically made in a multi-wall construction having a plurality of paper plies formed as a tube and laterally offset to provide seams for bonding. The top and bottom ends are usually stepped to provide opposing adhesive “laddered” bonding surfaces. These bags are generally called freight shipping bags in the industry.
In regard to such bags, there has begun a market demand for large side gussets of 5½-6″ and greater. It is recognized that bags having single gusset sizes of 5½″ or less work extremely well for small bags, such as for coffee, popcorn, vacuum cleaners, etc., because they are not highly load-stressed and may be manufactured on standard bag formers and filled on known bag spouting machinery.
The needs for larger gusset pinch closeable bags involve manufacturers who fill and ship the bags with higher bulk density products and that require greater bag volumes and pallet stackability, thus demanding a larger package. Such bulk products include pet foods, granulated food materials, flake-form materials, powdered and granular chemicals, agricultural products, such as potting soil bark, mulch, and the like. Accordingly, bag customers are requiring a wider range of capacity for a range of bulk densities. It is a goal in the industry to replace other bags that are limited in their capability for handling greater weights and volumes.
The industry has also found it beneficial to utilize large gusset bags in order to eliminate overhang when a shipment of bags is palletized.
The freight shipping packing and handling industries have found multi-wall bags with pinch closeable ends widely acceptable because of their relative ease in sealing and compatibility with well known bag closure equipment.
As the industry has sought to increase the size of gussetted pinch closeable bags, two major factors have arisen that compound the problem in producing the larger or wider side gussets required. As would be understood to those skilled in the art, the larger the gusset becomes, the more free board is needed to close the bag at the open end where the filling spout introduces the product. This means that extra paper is needed to close the top of the bag with paper covering the product so the bag has to be made bigger to accommodate this closure. The larger the gusset becomes the deeper the gusset ribs extend into the gusset of the end tuck and more room is required because these large ribs are difficult to push outwardly when the bag is being filled. This can cause irregular bag expansion that might lead to tearing and ripping. Heretofore, the multi-wall bag industry has not successfully developed or accepted large gusseted pinch closeable bags. Alternate ways have been attempted, such as by using other styles of bags. In great measure, larger gussets, i.e. those that would be generally about 6″ or more in width, are difficult to make in single standard fold gussets. Large percentages of the bags manufactured must be discarded as inferior. The bag-making production lines using the larger gussets also have to be run at slower speeds than non-gusseted pinch closeable bag line speeds. As the industry has experienced, urging these large gussets to form in the tuber, due to the bulkiness in size, creates difficulty in handling and machining during the bag making process. The standard guideline in the multi-wall freight shipping bag has been to not specify gussets that are over 5½″ wide. While certain manufacturers occasionally have provided these larger gussets, there is an inherent weakness at the gussets in large bags.
Antecedent to the present invention, bag manufacturers have not produced multiple gusseted pinch closeable bags. Instead, the industry has chosen to focus its effort in producing small-sized pinch bags having a standard single gusset, such as used for popcorn bags, small coffee bags, microwaveable bags, vacuum cleaner bags, and the like. Accordingly, smaller bags have become the norm with respect to utilizing side or lateral gussets. This is because the large gusseted bags have been found to require more timely machinery set-up for the tuber, former, and flattener, plus the impractical end result that they develop a higher waste at a lower production rate. When large gusset bags have been made in this fashion, the bag manufacturer simply accepts the inherent inefficiency and loss to meet an order of a customer.
Previous attempts at pinch closeable bags having gussets 6″ and over also have had several other problems. For example, when considering a standard 17″ by 33″ by 8″ bag, wherein the 8″ is the gusset and bag width dimension, the gussets are formed in the bag sides lengthwise of the bag creating two gusset walls having a v-shape arrangement. Thus, the gusset is indented 4″ deep on either side of the bag. When the bag lies empty ready to be filled, there are two 4″ tucks at either side wall for a total of 8″, thus leaving 9″ between the inner folds of the v-shapes for a 17″ wide bag. The room for spouting, filling and forming is thus lessened by 8″ compared to a non-gussetted construction. It has been found that single large gussets of this type have difficulty in being outwardly expanded during the filling process because all of the gusset is facing inwardly and the product mass has to push the gusset in the outward direction. The inherent weakness in forcing paper plies outwardly and at localized pressure zones can lead to bag rupture. There is a particular inherent weakness at the inside apex area of the v-shapes at the “manufactured end” (pre-sealed) of the bag. This can result in tearing and upward fracturing of the bag. The large gusset is difficult to fill out and square properly. The resulting gussets of a filled bag are often a little bit less than the intended bag width of 7 or 8″ because the product in the bag does not fully push out the v-shaped gusset. This reduction in bag depth can also affect the presentation of advertising or printing on the bag sides. As would also be clear, because of this inability to shape or “square out,” the filled bag may actually offer a diminished volume capacity inside the bag, which otherwise could be filled with the product.
Therefore, the major goals of the invention are (1) to provide more lateral or inboard room between gussets for forming, filling and spouting; (2) to create easier gusset-shaping during the filling step which allows the gussets to fill outwardly with less localized stress and less product pressure that would otherwise cause rupture in the previously known bags; (3) in providing larger gusseted (deeper) pinch-closeable bags, while maintaining sidewall strength, and (4) allowing the large gussets to be configured in a way so that the filled bags can subsequently be evenly stacked on a pallet without pallet overhang.
SUMMARY OF THE INVENTION
The present invention provides a multiple gusset for large freight shipping bags of the pinch closeable style wherein the manufactured end is pinch closed and the opposite open end is later sealed by the customer after filling the bag. The invention includes a unique step pattern and folded construction that when seal closed, satisfies industry wide drop testing strength, machine-ability, moisture barrier requirements, and seal closeability on standard pinch closure equipment. The invention may be summarized as providing a multiple gusset bag of greater than 5½-6″ depth utilizing an improved seal-closeable stepping pattern, upper and lower end gusset bonds, and a maximized space between inward folds of the gussets to satisfy fill spouting requirements.
Standard pinch closeable three-ply bags with bag widths from about 14-20″ have stepped multi-paper plies with a step pattern length about of 2&fr
Bemis Company Inc.
Lee Mann Smith McWilliams Sweeney & Ohlson
Pascua Jes F.
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