GB2439785A

GB2439785A - Composite packaging container having film-covered window

Info

Publication number: GB2439785A
Application number: GB0614968A
Authority: GB
Inventors: Jonathan Marx; Amy Wetton
Original assignee: Robinson Paperboard Packaging Ltd
Current assignee: Robinson Paperboard Packaging Ltd
Priority date: 2006-06-30
Filing date: 2006-07-27
Publication date: 2008-01-09
Also published as: GB0614968D0; GB0613062D0

Abstract

A composite packaging container comprises a rigid tubular body having a window opening formed therein. A film sleeve is a shrink-fit on the body so as to overlie the opening. The rigid body is formed and then an opening is cut in the body to form a window. The sleeve of shrinkable film material is then introduced over the body so that it overlies at least the opening therein, and the film material is then heat shrunk onto the body. The film may cover more than one such window and may be of transparent PVC. The body may be a spiral-wound paperboard tube.

Description

I

COMPOSITE PACKAGING CONTAINER

HAVING FILM-COVERED WINDOW

This invention relates to a composite packaging container having a film-covered window and in the preferred embodiment provides a packaging container based on a paperboard tube.

Composite packaging containers having film-covered windows are well known.

In general, such containers are macic by cutting a paperboard blank to define the overall container structure and define an open window in that structure. A sheet of suitable film material is then secured by adhesive bonding or welding to the reverse sw-lice of the blank so that when the container has been assembled from the blank a film-covered window is formed. This technique is not, however, applicable to circumstances in which the container is formed from a rigid tube, for example a spiral wound paperboard tube, For packaging containers based on such tubes there is at present no convenient method of forming a film-covered window.

According to one aspect of the present invention there is provided a composite packaging container comprising a rigid body having a window opening formed therein and a film sleeve which is a shrink-fit on the body whereby a portion of the film of the sleeve covers the opening of the window.

If desired the body may be provided with a plurality of window openings all of which are covered by the film sleeve.

The film sleeve may be made from PVC material having a thickness in the range of from about 50 microns to about 100 microns, although other film sleeve materials and other thicknesses could also be employed.

The present invention is particularly applicable to the manufacture of packaging containers which are based on paperboard tubes, for example spiral-wound paperboard tubes. The invention enables packaging containers based on such tubes to be manufactured with film-covered windows. It is to be understood, however, that the invention is not limited to such applications and may be applied to other packaging containers having rigid bodies.

In a first embodiment of the present invention a packaging container is formed with a body cut from spiral-wound paperboard tube. An opening is cut in the tube to form a window. The opening may be cut by any suitable means. A sleeve of shrinkable film material is then introduced over the body and shrunk by means appropriate to the film material to be a close fit over the surface of the body. In a particularly preferred embodiment of the invention the film material is a heat-shrinkable film and the film is shrunk into engagement with the body by heating. The length of the sleeve is such as to cover the window formed in the body, and preferably to cover at least some portion of the body above and below the window.

In one embodiment of the invention the film is a clear film which allows the exterior of the body to be viewed through the film. Such an embodiment will be suitable for applications where the exterior surface of the body is itself printed with graphic or textural material. In the second embodiment of the invention the film is printed externally or internally and is shrunk onto a body which is itself plain or pre-printed. In general, the area of the film which will in the finished container form the window cover will be clear or mostly clear so that the contents of the container are visible through the window.

By appropriate selection of the shrink characteristics of the film material the final form of the container may be such that the film covering the window adopts a position located radially inwardly of the outer surface of the body. Such an arrangement offers an interesting aesthetic characteristic to the packaging and may be functionally useful, particularly when the container is to house an item which has a preferred rotational position relative to the window. For example, if the packaging container is intended to house a bottle which has a front label it will be desirable for the front label to be visible through the window. By appropriately designing the dimensions of the window, and the shrink characteristics and surface characteristics of the film material, the portion of the film which forms the window may in fact engage the front surface of the bottle to prevent accidental rotation of the bottle after it has *1 been loaded into the packaging container.

The film may perform auxiliaiy functions. For example, the length of the film sleeve may be such that it extends beyond the top and/or bottom of the container. Jfthe film extends beyond the bottom of the container and as a result of shrink fitting underlies the lower edge of the container it will assist in retaining a bottom plug in the bottom end of the container. Alternatively or additionally, if the film extends over the top edge of the container it will assist in retaining a top plug. Either or both such arrangements may enhance the tamper-evidence of the pack. If desired, the film may be provided with a pre-formed tear strip to enable ready removal of: for example, the top edge of the film to facilitate removal of a top plug. Such a tear strip may itself form a tamper-evident feature.

If desired, the container can be pre-formed with the shrink film sleeve prior to filling and closed only after filling. This would be appropriate, for example, if the container is to be filled with a loose-fill, for example of pre-wrapped individual sweets. Alternatively, the container can be filled before the film is shrunk into final position. Such an arrangement would be suitable if the film is to fuLfil the role of preventing undesired rotation of the contents, for example in the form of a bottle.

Alternatively the design of the window and selection of the sleeve's shrink characteristics would allow for the bottle to be loaded into the tube after the container is pre-formed with the shrink film sleeve. In this case the bottle when being loaded into the container would deflect the film outwards at the window area and thus be retained from rotational movements. This design would also allow the user to remove and re-insert the bottle without damaging the film sleeve at the window area. If the container is to be pre-formed with the shrink film sleeve prior to filling it can, for example, be pre-formed with a closure plug in the top over which the film is shrunk to provide a tamper-evident feature as described above. The container can then be filled through the bottom thereof and the bottom subsequently closed in a conventional manner by, for example, a metal closure which is rolled into engagement with the paperboard material. (I

In a further embodiment of the invention a support surface is provided inside the rigid body adjacent the window opening whilst the shrink-fitting of the film sleeve is carried out. The support surface may be the surface of a mandrel that is located inside the body during shrinking of the sleeve. The surface of the mandrel in the region of the window may be of any form. It may, for example, closely follow what would have been the interior surface of the body in the zone of the window, if the window had not been formed in the body. For example, if the body is a right circular cylinder the support surface may be in the form of a part-cylinder having the same radius of curvature as the inside surface of the body. This can conveniently be achieved, for example, by use of a mandrel which is also of right circular cylindrical form and which is a close-sliding fit within the body. However, other forms of support surface are possible within the scope of the present invention.

In use, the support surface is positioned as required and the film sleeve shrink fitted onto the body. The support surface will, under these circumstances, constitute a former to define the final form of the film material in the region of the window. Thus, if the body is in the form of a right circular cylinder and the mandrel is in the form of a right circular cylinder which closely conforms to the interior of the body, the final form of the window will be a part-cylinder with a radius equal to the radius of the mandrel. After the film material has been shrunk and stabilised (e.g. by cooling if shrink fit is achieved through use of heat) the mandrel may be removed and the film will remain in its formed shape. This may give rise to particularly pleasing aesthetic characteristics which can, within the limits of the process, be determined by the nature of the profile of the support surface. P1 lb

Claims

Claims I. A composite packaging container comprising a rigid body

having a window opening formed therein and a film sleeve which is a shrink-fit on the body whereby a portion of the film of the sleeve covers the opening of the window.

2. A container according to claim 1, wherein the rigid body includes a plurality of window openings all of which are covered by the film sleeve.

3. A container according to claim I or claim 2, wherein the film sleeve is made from PVC material having a thickness in the range of from substantially 50 microns to substantially 100 microns.

4. A container according to any of the preceding claims, wherein the film sleeve is made of a heat-shrinkable material.

5. A container according to any of the preceding claims, wherein the length of the sleeve is greater than the length of the window so that it covers the window as well as at least some portion of the body above and below the window.

6. A container according to claim 5, wherein the length of the sleeve is greater than the length of the body and, upon shrinking, contracts around at least one of the top and bottom edge of the body so as to retain in place a closer plug engages therein.

7. A container according to any of the preceding claims, wherein the body is tubular.

8. A container according to claim 7, wherein the rigid body is a paperboard tube, in particular a spiral-wound paperboard tube.

9. A container according to claim 7 or claim 8, wherein the width of the window compared with the diameter of the tubular body is such that the film sleeve, when shrunk, adopts a position in which at least part of the sleeve lies radially inwardly of the outer surface of the rigid body, so that, in use, it engages against the outer surface of an item housed within the rigid body.

10. A container according to any of the preceding claims, wherein at least part of the film sleeve is transparent.

11. A method of making a composite packaging container according to any of the preceding claims, comprising the steps of forming a rigid body, cutting an opening in the body to form a window, introducing a sleeve of shrinkable film material over the body so that it overlies at least the openipg therein, and shrinking the film material onto the body.

12. A method according to claim 11, wherein the step of forming the rigid body comprises cutting it from spiral wound paperboard tube.

13. A method according to claim 11 or claim 12, including the further step of inserting a support surface into the container adjacent the window prior to shrinking the film material onto the body, the film material shrinking onto the support surface so as to shape the film material which overlies the window.

14. A method according to claim 13, wherein the support surface is formed by the surface of a mandrel.

15. A method according to claim 13 or claim 14, wherein the support surface is in form of a part-cylinder having substantially the same radius of curvature as the inside surface of the body such that film material is formed with a part cylinder shape over the window.

16. A composite packaging container substantially as herein described.

17. A method of making a composite packaging container substantially as herein described.