Envelopes – wrappers – and paperboard boxes – Paperboard box – With closure for an access opening
Reexamination Certificate
2000-10-10
2002-11-12
Elkins, Gary E. (Department: 3727)
Envelopes, wrappers, and paperboard boxes
Paperboard box
With closure for an access opening
C220S258500, C229S005500
Reexamination Certificate
active
06478218
ABSTRACT:
FIELD OF THE INVENTION
The present invention relates to composite containers, and in particular relates to composite containers for vacuum packaging fragile products, such as potato crisps or cookie biscuits, and associated methods.
BACKGROUND OF THE INVENTION
Food and drink products and other perishable items are often packaged in tubular containers that are sealed at both ends. For some time, it has been recognized that substantial economies, as well as environmental advantages, can be realized by the use of composite containers, as opposed to the traditional glass and metal containers. These composite containers typically include at least one structural body ply made of paperboard and are formed by wrapping a continuous strip of the body ply material around a mandrel of a desired shape to create a tubular structure. At the downstream end of the mandrel, the formed tube is cut into discrete lengths and fitted with end closures to form the container.
Tubular containers of this type typically include a liner ply on the inner surface of the paperboard body ply. The liner ply prevents liquids from leaking out of the container and also prevents liquids from entering the container and possibly contaminating the food product contained therein. Preferably, the liner ply is also resistant to the passage of gasses so as to prevent odors of the food product in the container from escaping and to prevent atmospheric air from entering the container through the liner and spoiling the food product. The liner ply is often a laminate including kraft paper, aluminum foil and/or one or more polymer layers. Thus, the liner ply provides barrier properties and the body ply provides structural properties for the composite container. In addition, a label ply is typically adhered to the outer surface of the paperboard body ply.
Certain food products benefit from being packaged while under a vacuum. Vacuum packaging removes oxygen from the space surrounding the product, which can improve the shelf life of the product within the package. This is especially true for perishable food products, or food products that may become stale if exposed to air. However, it is generally recognized that vacuum packaging in some tubular containers can only be accomplished with difficulty, if at all. Because of the structural design of the composite container, the application of vacuum to the interior of the container often results in partial or complete inward collapsing of the container walls along the length of the container. This can result in an unacceptable appearance for the composite container or an unacceptable sealing of the product within the container.
This problem is further discussed in U.S. Pat. No. 4,158,425, assigned to the assignee of the present invention and incorporated herein by reference. To avoid the partial or complete collapsing of the paperboard body ply of the container upon application of a vacuum inside the container, the container according to the '425 patent has an impermeable or hermetically sealed liner secured interiorly to the container body solely at the opposed ends thereof with the major length of the liner being free of the tubular body so as to allow an inward contracting of the liner without the introduction of excessive stresses to the container body itself. A vacuum or reduced pressure atmosphere within the liner causes an inward deformation of the liner into contact with the product substantially independently of the surrounding container body. Thus, the stresses which are transferred to the container body are at the opposed ends thereof which are in turn structurally supported by a pair of conventional end closures.
The '425 patent, however, only addresses the problem of collapsing of the container walls. The '425 patent does not discuss or provide a container designed to secure the food products during transportation or to prevent breakage of the food products during packaging. In particular, fragile food products, such as potato crisps or cookie biscuits, are extremely susceptible to breakage during transportation and packaging. These types of products are typically stacked within the container such that the products can move about the container. Although the '425 patent provides an inwardly moving liner, it is directed to sealing the product for freshness without damaging the tubular body, and not directed to providing cushioning support to the food products in order to prevent damage during transportation and packaging.
The problem of securing food products during transportation is addressed in copending application 09/543,439 entitled “Container and Method for Making Container for Fragile Products,” assigned to the assignee of the present invention and herein incorporated by reference. The container disclosed by the 09/543,439 application includes a flexible end closure secured to at least one of the opposed ends of the container that is free to move inwardly against food products contained therein when a vacuum is applied so as to provide cushioning support to the food products. As such, the food products are supported by a “pillow-like” cushion instead of a metal end closure or other rigid surface as provided by current containers. Despite the advantages provided by the flexible end closure disclosed by the 09/543,439 application, certain food products still suffer from breakage during the packaging process, particularly those products that are vacuum packed. In particular, it is believed that the vacuum packaging process causes the flexible end closure to move rapidly inward against the adjacent fragile products within the container, causing the products located near the end closure to be broken. Seeing broken cookies or potato crisps when the container is opened is very undesirable from a consumer standpoint and may lessen consumer appeal for the food products.
A conventional process for packaging food products includes sealing a flexible end closure, such as a membrane, to one end of the tubular container, inverting the container with the flexible end closure attached thereto, and depositing the products within the tubular container such that the products first deposited into the container rest against the inner surface of the flexible end closure. The remaining food products are then stacked upon one another until the container is sufficiently full. The filled container is placed inside a vacuum chamber and the chamber is depressurized to create a vacuum. The open end of the tubular container is then closed while the container and its contents are subjected to the vacuum. The vacuum chamber is then repressurized, which causes the flexible end closure of the sealed tubular container to move rapidly inward towards the food products. This rapid movement of the flexible end closure acts against the weight of the stacked food products that are resting against the inner surface of the flexible end closure. As such, the rapid movement of the flexible end closure results in a sharp pressing force against the food products, particularly against the food products adjacent the flexible end closure. The pressing force often results in breakage of the food products adjacent the flexible end closure, as these food products receive the brunt of the pressing force from the flexible end closure.
Accordingly, there is a need in the industry for a container that hermetically seals perishable food products, but that is also capable of protecting fragile food products during packaging, and particularly capable of preventing breakage of the food products located adjacent the end closures. At the same time, however, such a container would also be capable of withstanding the rigors of vacuum packaging so as to increase the shelf life of the product and provide other benefits attendant to vacuum packaging.
SUMMARY OF THE INVENTION
These and other needs are provided, according to the present invention, by a tubular container having an overcap secured to at least one of the opposed ends of the container that defines a bias member for biasing a membrane-type flexible end
Boatwright Floyd H.
Lowman Richard M.
Williams Alan D.
Alston & Bird LLP
Elkins Gary E.
Sonoco Development Inc.
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