Manufacturing container or tube from paper; or other manufacturi – Tube making – With coating
Reexamination Certificate
2000-05-15
2001-10-02
Vo, Peter (Department: 3721)
Manufacturing container or tube from paper; or other manufacturi
Tube making
With coating
C493S269000, C493S279000, C493S328000
Reexamination Certificate
active
06296600
ABSTRACT:
FIELD OF THE INVENTION
The invention relates to composite containers, and more particularly relates to adhesives for composite containers.
BACKGROUND OF THE INVENTION
Food and drink products and other perishable items are often packaged in tubular containers which are sealed at both ends. These tubular containers typically include at least one structural body ply and are formed by wrapping a continuous strip of body ply material around a mandrel of a desired shape to create a tubular structure. The body ply strip may be 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. At the downstream end of the mandrel, the tube is cut into discrete lengths and fitted with end caps 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 and spoiling the food product. Thus, the liner ply provides barrier properties and the body ply provides structural properties.
Conventional techniques for constructing composite containers involve flooding one surface of the paperboard body ply with a liquid adhesive to facilitate bonding of the body ply to the interior liner ply to form the composite container. Since the liquid adhesives contain a large quantity of water, usually at least 50%, a large amount of moisture is added to the container. In most cases, the moisture reduces the compression strength of the container. This requires additional processing steps to dry the container prior to shipping. These processing steps add cost and delay. As a result, there is a need in the art for a method of eliminating the added cost and reduced container strength caused by the addition of moisture to the container. In addition, the adhesives are not inexpensive and it would be desirable to decrease the total amount of adhesives used to reduce the cost of materials for each container.
SUMMARY OF THE INVENTION
The present invention provides a tubular container having a foamed adhesive layer adhering a paperboard body ply to other plies of a multi-ply container wall. The other plies may be additional paperboard body plies, liner plies, label plies, or the like. The use of the foamed adhesive reduces the amount of moisture that comes into contact with the paperboard body ply. This, in turn, avoids the reduction in container strength that results from excessive moisture within the paperboard body ply. The use of a foamed adhesive also reduces manufacturing cost by allowing reduced adhesive usage and eliminating or greatly reducing the time required to dry the container prior to shipping. Further, the reduction in moisture introduced into the process reduces atmospheric humidity within the building which, in turn, reduces air conditioning costs required to eliminate the moisture. An apparatus and method for manufacturing the tubular containers of the present invention are also provided.
The present invention provides a multi-ply tubular container for products having a first ply wrapped into a tubular shape and having an inner surface. The tubular container further comprises a second ply wrapped into a tubular shape and having an outer surface positioned in face-to-face contact with the inner surface of the first ply. At least one of the above plies comprises a body ply formed of fibrous paperboard. A foamed adhesive is placed between the inner surface of the first ply and the outer surface of the second ply to adhere the two plies together. The adhesive is a foamed liquid prior to the first and second plies being positioned in contact.
Preferably the foamed adhesive comprises a foamed aqueous adhesive. Aqueous adhesives suitable for use with the present invention include vinyl acetate/ethylene copolymers, vinyl acetate, starch-based adhesives such as dextrin, polyvinyl acetate, polyvinyl alcohol, protein adhesives such as casein or soy-based adhesives, acrylic adhesives and mixtures thereof. The foamed adhesive may be in the form of a substantially pure resin or a mixture of a resin and one or more fillers. The filler may be selected from the group consisting of clay, calcium carbonate, talc, barium sulfate, nephylene syenite, feldspar, inert fillers such as ground pecan shells, and mixtures thereof.
In one particular embodiment, the multi-ply tubular container comprises at least one paperboard body ply and a liner ply. The paperboard body ply is wrapped into a tubular shape and has an inner and outer surface. The liner ply has an inner surface facing the interior of the container and an outer surface positioned in face-to-face contact with the inner surface with the paperboard body ply. Preferably, the liner ply includes a moisture and/or gas barrier layer. A foamed adhesive is placed between the inner surface of the paperboard body ply and the outer surface of the liner ply to adhere the plies together. Again, the adhesive is a foamed liquid prior to the body ply and liner ply coming into contact. Preferably the liner ply is substantially entirely formed of polymeric material; however, the liner ply may be constructed of various combinations of polymeric layers, paper layers, and aluminum foil layers.
The tubular container of the present invention can also include a label ply. The label ply preferably has an inner surface positioned in face-to-face contact with the outer surface of the paperboard body ply. A foamed adhesive is placed between the outer surface of the paperboard body ply and the inner surface of the label ply to adhere the plies together. The adhesive is a foamed liquid prior to the plies coming into contact.
The tubular container of the present invention may also include a second paperboard body ply having an inner surface positioned in face-to-face contact with the outer surface of the first paperboard body ply. Again, a foamed adhesive is placed between the outer surface of the first paperboard body ply and the inner surface of the second paperboard body ply to adhere the two plies together. The adhesive is a foamed liquid prior to the plies coming into contact.
An apparatus for manufacturing multi-ply tubular containers includes an adhesive foamer operatively connected to an adhesive applicator for supplying foamed adhesive to the adhesive applicator. The adhesive applicator is located adjacent to one surface of a body ply and applies a foamed adhesive to the surface of the body ply. The body ply is supplied in the form of continuous body ply material. A supply of continuous liner ply material is also provided. A shaping mandrel is positioned to adhere the body ply and the liner ply together with the foamed adhesive to form the two plies into a tubular shape. Advantageously, the apparatus further includes a cutting station adjacent to one end of the mandrel for cutting the tubular shape into discrete container lengths.
The apparatus of the present invention further includes a supply of continuous label ply material and a second adhesive applicator adjacent to one surface of the label ply for applying a foamed adhesive to the surface. The second adhesive applicator is operatively connected to the adhesive foamer for receiving foamed adhesive. The label ply is wrapped around the body ply downstream of the second adhesive applicator and adhered thereto with the foamed adhesive.
As described above, the tubular container of the present invention may also include additional body plies. In turn, the apparatus of the present invention may include a second supply of continuous body ply material and another adhesive applicator positioned adjacent to one surface of the second body ply for applying a foamed adhesive to the surface. The second adhesive applicator
Drummond Michael T.
Williams Alan D.
Alston & Bird LLP
Sonoco Development Inc.
Tawfik Sam
Vo Peter
LandOfFree
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