The present invention relates to composite containers for food products, and more particularly, to multi-ply containers constructed of a paperboard body ply, an inner liner ply and a label ply.
Multi-ply composite containers are used for packaging a wide variety of food and drink products as well as other perishable items. These multi-ply containers are constructed to be opened at either one of two spaced ends that are sealed, either permanently or with a removable seal. Some of these containers can also be opened along a sidewall seam in order to gain product access. To package such perishable food products, a container is required that is rigid enough to retain its shape during shipping and when subjected to internal pressure that is sometimes produced in the container, while tightly sealing the food product to protect against deterioration, leakage and contamination. Thus, these composite containers conventionally include three separate plies or sets of plies and two end closures.
First, at least one structural body ply made of paperboard material is included, which is formed into a tubular structure by wrapping a continuous strip of body ply paperboard material around a shaping mandrel. The body ply is spirally wound around the mandrel or passed through a series of forming elements so as to be wrapped in a convolute shape around the mandrel. These containers also typically include a liquid impermeable liner ply adhered to the inner surface of the paperboard body ply. The liner ply seals the food product within the container, and also prevents liquids, which may possibly contaminate the food product, from entering the container. Some liner plies are also gas impermeable, so as to not only prevent food product odors from escaping the can, but also prevent atmospheric air from entering the container and spoiling the food product. Thus, while the purpose of the body ply is to provide necessary structural properties to the container, the liner ply provides various properties necessary to contain and maintain the perishable food product.
A label ply is also included, and is adhered to the outer surface of the paperboard body ply. The label ply serves two primary functions. First, a composite can label is a source of information. The label carries graphical matter that conveys product information, instructions, and regulatory compliance information. The label is also aesthetically pleasing to the consumer, which enhances shelf appeal and increases consumer interest in the food product.
In addition to the three separate plies which make-up the multi-ply composite container, these composite containers typically also include metallic or plastic end closures configured to engage the end portions of the paperboard body ply. The metal or plastic ends serve to provide rigidity to the composite containers while retaining the food product.
A critical factor in composite container design is the ease with which such containers may be opened, and composite containers are often designed to incorporate different opening features. For example, composite containers for leavened dough products are normally opened by removing completely the label ply from the paperboard body ply, whereupon the container is forcibly struck against a sharp surface, such as the edge of a kitchen counter. The force of striking the container against the sharp surface, in conjunction with internal can pressure produced by the leavened dough, causes the helical butt joint of the body ply and the inner liner ply to rupture, exposing the food product and allowing it to be removed from the container. For example, U.S. Pat. No. 2,949,369 to Zoeller discloses a compartmented dough package for storing leavened dough wherein when the container is to be opened so as to prepare the food product stored in the can for use, the can sidewall is circumferentially split and the product can readily be removed from the container.
Where the food product is potato crisps, on the other hand, the composite container is typically designed with a metal closure at one of its ends, and a removable foil seal with a plastic end cap at the other. In this way, the container is easily reclosed after the foil seal is broken. Thus, left over food product can be easily stored in the reclosable container.
One common problem with composite container designs is that one or more of the metal or plastic ends of these containers remain attached in whole or in part to the can body after the can is opened. Thus, the end closures are difficult to remove from the can body to permit recycling of the can body and the ends. This often results in expensive and complicated opening features, and composite containers which are difficult to recycle because the ends and the body ply are made of different materials.
Another problem commonly associated with composite container product packaging is that the volume of the composite container is fixed, while the volume of the food product within the container diminishes as the food is consumed. Thus, when a tall, narrow tubular food product container is used to package snacks or other consumable products such as potato crisps, the consumer is often unable to reach the food near the bottom of the container. The container is too small in diameter to allow an adult hand to reach into the container, and too tall to allow the fingers alone to reach the food near the container bottom.
Some container designs have attempted to overcome this problem using a sectionable container. For example, U.S. Pat. No. 2,969,902 discloses a container having a plurality of sections which are separately removable with different portions of the body. The design of the ""902 patent is limited, however, in that it is constructed using a complicated series of premanufactured rings and sections that are assembled and then secured together by a sheet of material adhesively secured around the rings. Furthermore, the label on the outside of the container must be cut so that the container may be sectioned making the container difficult to break apart.
Accordingly, it would be desirable to provide a low cost multi-ply composite container and a method for manufacturing such a container which provides for easy opening, better consumer access, and encourages consumer recycling. Such a container would not only result in decreased production costs and reduce inefficiencies in the manufacture of composite containers, but would also result in an xe2x80x9cenvironmentally friendlyxe2x80x9d composite container.
These and other objects and advantages are provided, according to the present invention, by a multi-ply composite container for consumer products with at least one region of weakened strength. The multi-ply composite container comprises a multi-ply composite tube that includes a body ply formed of paperboard material, a liner ply adhered to the inner surface of the tubular body ply and a label ply adhered to the outer surface of the body ply. The multi-ply composite tube also comprises at least one circumferential score line in the multi-ply composite tube through the label ply and the body ply that creates a region of weakened strength. The circumferential score line may extend partially around the circumference of the multi-ply composite tube or around the entire circumference of the multi-ply composite tube. This at least one circumferential score line advantageously allows the volume of the multi-ply composite container of the present invention to be reduced as the volume of food product in the container is reduced. The multi-ply composite container may also advantageously include at least one angular score line in the multi-ply ply composite tube through the film label ply and the body ply intersecting the circumferential score line.
In one embodiment, the composite container also includes at least one composite end closure having a liner ply and a body ply that is secured to one of the two opposed ends of the multi-ply composite tube. In this embodiment, at least one arcuate score line through the body ply of the end closure may be included to advantageously create a region of weakened strength in the composite end closure. In another embodiment, at least one angular score line may also be included through the body ply of the composite end closure intersecting the arcuate score line. Such an arrangement makes the multi-ply composite container of the present invention more environmentally friendly because it provides for composite end closures as opposed to metallic or plastic end closures.
The advantageous method of forming a multi-ply composite container for consumer products with at least one region of weakened strength includes the steps of advancing a continuous body ply formed of paperboard material towards a shaping mandrel and advancing a continuous liner ply having a moisture barrier layer towards the shaping mandrel. The body ply and the liner ply are then wrapped around the shaping mandrel to adhere the liner ply to the body ply. Next, a continuous label ply is advanced towards the shaping mandrel downstream of the adhered liner ply and body ply. Then, the label ply is wrapped around the body ply and the liner ply to adhere the label ply to the body ply and the liner ply to create a multi-ply composite tube. The multi-ply composite tube is then scored through the label ply and the body ply to create a region of weakened strength in the composite tube.
The step of scoring the label ply and the body ply may comprise perforating the multi-ply composite tube or grooving the multi-ply composite tube. In one embodiment, the scoring step includes scoring the label ply and the body ply with a laser. In another embodiment, the scoring step includes scoring the label ply and the body ply with a knife.
Consequently, the container and method of the present invention overcome limitations imposed by conventional composite containers and methods of manufacturing such containers. In particular, the multi-ply composite container and method for manufacturing same of the present invention provide a composite container which provides for easy opening, better consumer access, resealability, storage for left over food product and encourages consumer recycling. The container and method of the present invention will therefore not only result in decreased production costs and reduce inefficiencies in the manufacture of composite containers, but also will produce a more useful, xe2x80x9cenvironmentally friendlyxe2x80x9d composite container.