WO2013114072A1

WO2013114072A1 - Tear opening means for a paperboard container

Info

Publication number: WO2013114072A1
Application number: PCT/GB2013/000041
Authority: WO
Inventors: Samantha Moore
Original assignee: Colpac Limited
Priority date: 2012-02-02
Filing date: 2013-02-04
Publication date: 2013-08-08
Also published as: GB201201874D0; GB2499009A

Abstract

The invention relates to a means for opening a container, said container being particularly, but not exclusively, for receiving a food product. The container includes opening means (11), said opening means (11) comprising a tab (12), and said tab (12) is bonded to a first flange (8) of said container. The tab (12) of the opening means (11) includes a line of weakness (13) which abuts an edge on said first container flange (8) such that, in use, opening of said container is achieved by initiating a tear in the tab (12) of the opening means (11) along the line of weakness.

Description

TEAR OPENING MEANS FOR A PAPERBOARD CONTAINER

The invention relates to a means for opening a container, wherein said container is particularly, but not exclusively for receiving a food product. The invention also relates to a blank for forming a container with said opening means and a method of forming said container from said blank.

It is known to package some food products, such as sandwiches, in hermetically sealed containers which are formed from a folded blank of material, such as paperboard. For the purpose of this specification 'paperboard' is considered to encompass paper, cardboard and similar materials.

In order to extend the shelf life of these packaged food products, it is desirable to reduce, preferably to zero, the amount of oxygen remaining in said sealed container. This can be achieved by vacuum packaging, where the air within the packaging is simply removed, or gas flushing, where the atmosphere within the packaging is flushed out by the addition of one or more gases such as nitrogen, argon or carbon dioxide. Most preferably, a technique known as 'modified atmosphere packaging' can be employed, whereby the air in the container is first removed and subsequently replaced by one or more gases as described above. The initial step of sucking out the air prevents residual oxygen being left in the container, which is one typical problem associated with gas flushing.

The success of modified atmosphere packaging is dependent on the quality of the hermetic seal provided on the container. Numerous attempts have been made to modify the design of packaging in such a way that a suitable seal can be formed, and numerous patent applications have been filed directed to these developments. One key advance has been the use of plastics films to provide an impermeable layer across the entirety of the interior surface of a paperboard container/blank. However, improving the quality of the hermetic seal leads to packaging that can be difficult to tear open. It is an object of the present invention to provide a hermetically sealable paperboard container formed from a blank wherein, in use, a tear can easily be initiated in said container by a user in order to access the container contents but wherein the integrity of the hermetically sealed container is not compromised in order that said tear can be easily made. It is a further object of the invention that formation of the container should be straightforward.

According to the present invention there is provided a container according to the appended claim 1. The container according to the present invention retains its integrity at the points where one portion of laminated paperboard is sealed to another to create a double layer of paperboard, but also comprises a line of weakness in said paperboard at a point where a single layer of paperboard extends from said double paperboard layer. This enables easy tear opening of said sealed container in conjunction without compromising the quality of hermetic sealing of said container.

Further advantageous features of the invention are recited in the dependent claims 2 to 15.

The container is preferably a food product container, in particular a sandwich pack. The container may be formed from paperboard, in particular from a paperboard blank, in which case a liquid impermeable coating is preferably provided on at least the interior surface of said blank to prevent ingress of liquids into the paperboard.

The line of weakness may be a score line, such as a partial depth cut line or line of compressed paperboard, or a cutout portion of the paperboard, or, preferably a cut through said paperboard and/or laminate. This region of weakness in the paperboard and or laminate allows a user to initiate a tear in said paperboard more easily than compared to paperboard that does not include said feature. The closure flap opening means may, advantageously, be bonded to a second flange of said container to improve the integrity of the seal at the opening means. The more easily tearable opening means allows for bonding of said second flange without making tearing open of the opening means overly difficult.

Preferably a layer of heat sealable film is provided between the first and second container flanges and bonded to the opening means. The line of weakness may extend through both the the layer of heat sealable film and the paperboard, or alternatively, the line of weakness may abut the edge of the layer of heat sealable film and, further preferably, the line of weakness may not overlap the layer of heat sealable film. A non-overlapping arrangement enables a tear to be initiated in just the paperboard opening means and does not require simultaneous initiation of a tear in the paperboard and heat sealable film.

The container is preferably formed from a folded blank and, advantageously, the bonding is such that the container is hermetically sealed. Advantageously, the blank is formed by bonding the tab of the opening means to the first flange of the container and by forming a line of weakness in said tab which abuts an edge on said first container flange. Preferably, the line of weakness is formed in the blank at approximately the same time in the manufacturing procedure that said blank is cut, i.e. when the blank is cut from a single piece of paperboard using a conventional technique such as die-cutting. Alternatively, the step of bonding the tab to the flange is performed before or substantially simultaneously with the step of forming a line of weakness in said tab which abuts an edge on said first container flange such that said line of weakness formed in the tab of the opening means is aligned with the edge of the flange bonded to the first flange of the container. Performing the steps in this order enables quick and simple assembly of the container from the blank because it removes the need to accurately align the tab and flange when bonding said features together.

A better understanding of the present invention will be obtained from the following detailed description. The description is given by way of example only and makes reference to the accompanying drawings in which: Figure 1 is a plan view of a blank suitable for forming a container according to the present invention;

Figure 2 is a perspective view showing a partially folded blank according to the present invention;

Figure 3 is an end view of a partially folded blank according to the present invention;

Figure 4 is a side view of a blank according to the present invention folded to form a sealed container according to the present invention;

Figure 5 is a plan view of the folded blank of Figure 4;

Figure 6 is an underside view of the folded blank of Figures 4 and 5;

Figure 7 is a partial view of the underside of the folded blank of Figures 4 to 6, showing initiation of a tear;

Figure 8 is a partial view showing propagation of the tear of Figure 7; and

Figure 9 is partial perspective view of an alternative blank according to the present invention.

Figure 1 shows a plan view of a blank 1 suitable for forming a container according to the present invention. The blank 1 has a paperboard substrate which is cut from a single piece of paperboard using a conventional technique such as die-cutting.

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The blank 1 shown in Figure 1 is for a sandwich container and, once folded, provides a container with a generally triangular profile for receiving diagonally cut sandwiches. The surface of the blank 1 shown in Figure 1 (the first surface) will form the inside of the finished container and comprises a layer of laminated plastics film. The second surface of the blank 1 , opposite to the first surface, will form the outside of the finished container. The film layer is applied over the entire first surface of the paperboard and serves as both a moisture impermeable barrier and as a heat sealable medium for sealing the finished container and, in some cases, also for bonding the container walls together.

The blank 1 comprises first and second generally rectangular end walls 2, 3 which are connected to each other along their common short edge by a fold line to form the apex of the folded container. A pair of generally triangular side walls 4, 5 is connected by further fold lines to the long edges of each of the end walls 2, 3 , specifically the pair of generally triangular side walls 4 is connected to the first end wall 2 and the pair of generally triangular side walls 5 is connected to second end wall 3. In the particular embodiment shown, the sides of the first and second generally rectangular end walls 2, 3 taper away from their common fold line such that the finished container has an opening that is wider than the apex of the Container to aid insertion of the cut sandwiches. This is not, however, essential.

The blank 1 also comprises a generally rectangular closure flap 6 joined by a fold line along one of its short edges to the short outside edge of the first generally rectangular end wall 2. A window 7 is provided in the closure flap 6 to allow a user to view the contents of the container once it is sealed. In the illustrated embodiment the window 7 is provided as an aperture in the paperboard substrate which is covered by the continuous laminated film layer. This helps to maintain an optimum seal by avoiding discontinuities in the closure flap 6. However, it is also possible for the window 7 to be covered by a separate piece of film if the coating of the paperboard is achieved by alternative means, such as by spraying.

The two outside edges of each of the generally triangular side walls 4, 5 are joined by a fold line to generally rectangular flanges 8. The film layer extends beyond the edges of the paperboard to bridge the gap between the flanges provided on each generally triangular side wall 4, 5, such that substantially triangular areas 9a, 9b, and optionally 9c, 9d, of unsupported film are provided. Similarly, a generally rectangular flange is joined by a fold line to the short outside edge of the second generally rectangular end wall 3 and the film layer extends beyond the edges of the paperboard to bridge the gap between said flange and adjacent flanges provided on the adjacent triangular side walls 5 such that substantially triangular areas 9e, 9f of unsupported film are provided. The film areas provide a continuous flange around the side walls 4, 5 of the blank 1 such that the blank 1 can be hermetically sealed when folded into a container. The flange 8 joined by a fold line to the short outside edge of the second generally rectangular end wall 3 forms part of an opening means 1 1 , in conjunction with an adjacent flange 8 on the adjacent triangular side, wall 5 and the triangular area 9f positioned between said adjacent flanges 8. The opening means 1 1 will be described in more detail hereafter. The opening means 1 1 comprises a tab 12 provided proximate one of the corners of the short outside edge of the generally rectangular closure flap 6. The tab 12 extends outwards from both a long outer edge and the short outer edge of the closure flap 6 at an angle of approximately 45 degrees. The tab 12 is generally rectangular with two outermost corners removed. Extending at an angle of approximately 45 degrees to the closure flap 6 outer edge, substantially parallel to opposing edges of the tab 12 and substantially perpendicular to the long outside edge of the tab 12 is a line of weakness 13 formed in the paperboard of the blank 1 . The line of weakness 13 is a line in the paperboard of the blank 1 that is of reduced strength, and so more easily tearable, than compared to the majority of said paperboard. The line of weakness 13 is of the form of a full or partial depth cut line such as a groove or score line. Alternatively, the line of weakness 13 may be provided by removal of a channel of paperboard in the tab 12 or other suitable means.

As mentioned above, when the blank 1 is folded to form a container the adjacent flanges 8 on the generally triangular side walls 4, 5 are bonded together and the remaining flanges 8 are bonded to the closure flap 6. This is shown progressively in Figures 2 to 6. At the corner of the container where the tab 12 of the opening means ) 1 is provided on the closure flap 6, ends 14 of the two flanges 8 that are coincident with said corner are shaped so as to, in combination with triangular film area 9f, substantially cover the first surface, i.e. the laminated surface, of said tab 12. The exception to this is that a substantially rectangular portion of the inside, laminated face of the blank 1 , is not connected to the flanges 8. Accordingly, and as shown most clearly in Figure 6, when the blank 1 is folded into a container the line of weakness 13 is positioned on the tab 12 such that it is aligned with, i.e. abuts, an edge on a flange 8. The position of the line of weakness 13 enables a user to initiate a tear in the tab 12 of the opening means 1 1 without, at the same time, having to initiate a tear in the flange 8 or film area 9f bonded to said tab 12. In other words, a user is only required to initiate a tear in a single sheet, or thickness, of paperboard rather than through a double thickness of paperboard which is present along the edges of the closure^'' flap 6 where said flap 6 is bonded to the flanges 8 of the folded container.

This design of the opening means 1 1 greatly improves the ease of which a hermetically sealed container can be opened without compromising the extent, and thus integrity, of hermetically bonded laminate provided between the closure flap 6 and the flanges 8 of the folded container. In addition, the tab 12 of the opening means 1 1 can be smaller than is typically present on opening means of hermetically sealed paperboard containers because less force is required to initiate a tear in, and thus open, the container.

A further advantage of the alignment of the line of weakness 13 with an edge on a flange 8 bonded to the tab 12 of the opening means is that the flange edge controls the direction of propagation of a tear initiated in the tab 12 of the opening means 1 1. The tear is guided by the flange edge such that it propagates substantially adjacent to said flange edge. This enables a controlled tearing of the closure flap 6 and thus a controlled opening of the container. An example of the propagation of the tear along the line of weakness 13 towards and subsequently through the triangular area of film 9f is shown in Figures 7 and 8.

The line of weakness 13 is preferably formed when the blank 1 is formed. Alternatively, the line of weakness 13 is formed in the tab 12 of the opening means J J after the blank J has been folded to form a container and either following, or at substantially the same time as, the flanges 8 are bonded to said tab 12. This enables the line of weakness 13 to be precisely aligned with the flange 8 in the manner described above. Forming the line of weakness 13 after or during bonding of the container also removes the need to ensure the tab 12 and flanges 8 are brought together accurately such that the line of weakness 13 is positioned exactly as previously described. Th is enables the container to be made more quickly and easily than if the line of weakness were formed prior to folding of the blank 1 in to the container.

In addition, forming the line of weakness 13 may involve weakening or cutting a portion of the flange 8 after it is bonded to the tab 12 of the opening means 1 1. For example, the flange 8 and tab 12 may be bonded together and then, subsequently, a cut is made through overlapping portions of both the tab 12 and the flange 8. This would result in a line of weakness being quickly and simply formed in the tab 12 which is adjacent and abutting an edge of the flange 8. As above, this would allow the flange 8 and tab 12 to be bonded together quickly, without the need to align precisely to a pre-formed line of weakness 13. The line of weakness 13 may be formed in the paperboard or the paperboard and laminate by scoring the tab 12 of the opening means 1 1 with two knives l -2mm apart, by cutting through said tab 12, or by forming a cutout, for example by removal of a 3mm wide piece of paperboard from said tab 12 during the manufacture. It will be understood that the line of weakness 13 may also be a point or notch which enables a user to more easily initiate a tear in a single sheet of paperboard or laminated paperboard. It will also be understood that the line of weakness 13, for example a score line, may continue in the tab 12 adjacent the flange and further continue along the inside, laminated face of the closure flap 6 or along the fold line connecting the flange 8 to the triangular side walls 4, 5, such that tearing open the container is further simplified. An example of the tear propagating in this manner is shown in Figure 8.

The container shown in Figures 2 and 3 is ready to receive a sandwich. Once the container has been filled the closure flap 6 is closed and heat sealed to the flange 8 of the container. Modified atmosphere packaging techniques, for example vacuum packaging or flushing the container with an inert gas, can be used as required. The invention is not considered to be limited to the configurations and materials described above, for example, the line of weakness 13 may be formed in the ends 14 of the flange 8 proximate the tab 12, rather than the tab 12 itself - the inventive principle of initiating a tear in one layer of paperboard before another and said tear being guided by an edge would remain.

While the description is limited to a container formed from a paperboard blank, the principles of the invention would also be applicable to similar containers made by other means. Furthermore, the shape of the container and the blank 1 from which it can be formed may vary from that described as may the dimensions and, to a certain extent, the materials used. For example, a container formed from a blank in which the closure flap 6 hinges along one of its longest sides is shown in Figure 9. The principle of the tear opening means described above is shown.

Claims

1. A container including opening means, said opening means comprising a tab, ■ wherein said tab is bonded to a first flange of said container and said tab includes a line of weakness which abuts an edge on said first container flange such that, in use, opening of said container is achieved by initiating a tear in the tab of the opening means along the line of weakness.

2. A container according to claim 1 , wherein the line of weakness is a partial depth cut line.

3. A container according to claim 1 , wherein the line of weakness is a cutout portion.

4. A container according to claim 1 , wherein the line of weakness is a cut-through portion.

5. A container according to any of the preceding claims, wherein the opening means is bonded to a second flange of said container.

6. A container according to claim 5, wherein a layer of heat sealable film is provided between the first and second container flanges and bonded to the opening means.

7. A container according to claim 6, wherein an end of the line of weakness abuts the edge of the layer of heat sealable film.

8. A container according to claim 6 or claim 7, wherein the line of weakness does not overlap the layer of heat sealable film.

9. A container according to any of the preceding claims, wherein said container is formed from a folded blank.

10. A container according to any of the preceding claims, wherein the bonding is such that the container is hermetically sealed.

5 1 1. A container according to any of the preceding claims, further comprising a closure flap, and wherein said closure flap includes the tab.

12. A blank for forming a container according to any of the preceding claims.

10 13. A method of forming a container from a blank according to claim 12, comprising the steps of a) bonding the tab of the opening means to the first flange of said container and

15 b) forming a line of weakness in said tab which abuts an edge on said first container flange.

14. A method according to claim 13, wherein step (a) is performed before or substantially simultaneously with step (b) such that the line of weakness formed in the tab of the opening 0 means is aligned with the edge of the first flange bonded to said tab.

15. A method according to claim 13, wherein step (b) is performed when the blank is formed. 5