EP2684808A1

EP2684808A1 - Closure for a container and a container provided therewith

Info

Publication number: EP2684808A1
Application number: EP12175592.0A
Authority: EP
Inventors: Fabrice Leboucher
Original assignee: Ardagh MP Group Netherlands BV
Current assignee: Trivium Packaging Group Netherlands BV
Priority date: 2012-07-09
Filing date: 2012-07-09
Publication date: 2014-01-15
Also published as: WO2014009195A1

Abstract

The present invention relates to a closure (19) for a container, comprising, a tab (3) attached by rivet means (4) to a closure part to be removed for forming an opening in the closure, which opening is defined by a score line (8) formed in the closure, and stiffening means (20) extending along the rivet means towards the score line, and to a container provided with such closure.

Description

The present invention relates to a closure for a container, and to a container provided with such a closure.
The present invention relates to a closure for a container and in particular to a closure for an easy opening container. An easy opening container is a container which the consumer can open without the use of a tool. Thereto, the easy opening container is provided with a closure having a tab with which the consumer is able to form an opening in the closure along a score line, and subsequently at least partially remove the closure part provided with the tab thereby forming an opening in the closure and to make access to the container content. The container opening procedure to be followed by the consumer comprises first a lifting of the tab from the closure surface whereby the tab will rotate and the tab nose will press near or on the score line. The score will fail thereby popping open the closure. The construction of the tab is such that the rotational force for lifting the tab and for forming the initial opening in closure should be sufficiently low for easy opening. Thereafter, with the tab in an upright position the consumer has to pull the tab thereby tearing the closure part attached to the tab loose from the remainder of the closure so that the closure part is torn along the score line apart from the closure thereby forming the opening.
Obviously, not only the rotational force for lifting the tab but also the opening tear force should be sufficiently low in order to acquire easy access to the content of the closure.
Generally, a closure for a container of the type as described above comprises a tab which is attached by rivet means to the closure. The rivet means should be such that the tab is reliably attached to the closure and will not fail or even release during the lifting or tearing of the closure part during the opening of the container and thereby being separated in an undesired manner from the closure part. Such a situation is not desired and even dangerous because generally the torn score line comprises a sharp torn edge.
For a reliable and easy popping open of the closure it is preferred that the area where the initial opening of the closure occurs is relatively stiff because a stiff will be easier to pop open than a flexible closure. However, due to the structural elements present in the closure for attaching the tab via the rivet means to the closure part this area of the closure is generally stretched and relatively thin and vulnerable, particularly when the rivet means are made from the closure part material and are integral with the closure part. In addition, when the content of the closure is pressurized, it should be avoided that when having a weaker area an undesired opening by peaking could occur.
The above considerations require a tab to be reliably attached by the rivet means to the closure part, for having an easy opening of the container with the tab and without a tool. Preferably such container is also suitable for pressurized contents in the container. In view of these considerations, the skilled person will acknowledge that the area were the tab nose will act on the score line for popping open the closure and forming a so-called opening chord along the score line, is an area full with compromises for balancing conflicting constructional features. The closure should be easily opened but still sufficiently rigid for withstanding internal pressures and easy popping. Therefore, this delicately designed area is unlikely for the skilled person to include or be imparted further construction measures in relation to an improvement of the opening of a closure as described above, but which may interfere with the existing easy opening construction.
Still, the present invention relates to further improvement of the closure in particularly in the area where the tab acts with its tab nose on the score line for popping open the closure, for further improving the opening procedure and for reducing in particular the tear force for forcing an opening in the container.
According to the invention is provided a tab attached by rivet means to a closure part to be removed for forming an opening in the closure, which opening is defined by a score line formed in the closure, and stiffening means extending along the rivet means towards the score line.
The present invention is based on the insight that providing stiffening means near the area where the tab nose will interact with the score line, that the stiffening of this area will result after popping open the closure in the formation of an opening chord and arc along the score line over a larger length such, that the subsequent tear force required for tearing the closure at least partially part with the tab along the score line apart from the remainder of the closure thereby forming an opening, will be lowered to a surprisingly large extent. The stiffening means according to the invention are located along the rivet means and extend from the rivet means towards the score line in essentially a direction which is close to a radial direction. This has a result that at the same rotational force applied by the consumer when lifting the tab, after popping open the closure a larger initial opening is formed and therefore longer opening chord and opening arc.
The stiffening means according to the invention may have any form which will provide an increase in stiffness in the area at the side and preferably ahead of the rivet towards the score line. Such stiffening means may comprise any type of stiffening elements, such as stiffening bars or stiffening grooves and other structural forms that will improve the stiffness although they will not interfere with the properties of the closure and of the container in relation to a reliable closure and a reliable easy opening of the closure.
In a preferred embodiment a closure for a container according to the invention may comprise at least one furrow which extends along the score line. If this furrow extends along the score line which encloses the furrow, then it is preferred that the stiffening means are connected to this furrow. This will provide for an area with an increased stiffness which may change only gradually in stiffness, whereas the stiffening means and the furrow may be formed in the closure during the same forming operation. In a preferred embodiment the furrow is a circumferential furrow which partially or preferably substantially encloses the removable closure part of the closure.
According to a preferred embodiment the closure is provided with two circumferential furrows each extending at a side along the score line. Such closure has a high strength. The scoring may be done at a relatively low scoring force and even may result in a use of a less thick closure material.
It should be noted that the score line may be a closed score line so that the closure part may be removed entirely from the closure and becomes eventually separated from the closure. Such score line may be circular, ellipsoid, or any suitable form. On the other hand, the invention also relates to a score line which is not a closed score line, so that the closure part to be removed for forming the opening will remain attached to the closure in an area where the closure is not provided with the score line. Such score line may have to form of a crescent or other suitable form.
According to another preferred embodiment the furrow may extend laterally of the rivet means and only along a part along the score line. Obviously, also in this case the stiffening means may be connected and formed together and integrally with this type of furrows.
As stated above, the rivet means may comprise a separated rivet which is formed in the closure via a rivet opening formed in the closure, so that the rivet is extending through this rivet opening and attaches the tab to the closure. In a preferred embodiment the rivet means have the form of a rivet made from the material of the closure, so that the rivet means are integrally formed from the closure part. Such integral forming requires the provision of closure material for the rivet means by stretching additionally the closure adjacent the area where the rivet means are to be formed integrally from the closure material. Evidently, such integral rivet means has the advantage of providing a closure not having an opening for the rivet.
As stated above, the stiffening means are intended to provide the area where the tab will act on the score line with a more stiff closure region. The stiffening means may have any form such as an elongated form being strait, curved, and wavy, or combinations thereof. Other forms such as a serpentine form, fish grate form and other well known form which will result in stiffening of a panel, may be considered as stiffening means to be used according to the present invention.
It is preferred, that the stiffening means have the form of a groove which is a form similar to a furrow and which may be formed in the material during the formation of the closure. Such a groove may be open to the inner side of the container but preferably open to the tab side of the closure part, so that it will have a form similar to other structures formed in the closure for the same or other reasons. Such other forms may comprise a terrace structure, dimples form supporting the tab rear part, and evidently furrows and serpentine furrows for increasing the strength of the closure.
As indicated above, the presence of the stiffening means is selected such that an opening chord formed upon opening the closure by the rotational force of the tab such opening chord is longer than an opening chord formed in the closure devoid of the stiffening means according to the invention. The chord will be larger and surprisingly thereby the force for tearing further open the closure is reduced.
The tear force for opening the closure is generally measured and tested with a tear force opening test. In the testing apparatus the tab is connected to the pulling element and preloaded (pre-load about 1N). The closure is rotated over about 90° whereby the tab is brought into an upright position and the closure is popped open. The detected maximum force is the pop force. The tab is pulled against the rim of the closure and then the closure is rotated back to the tear position at about 4°. The tab is then pulled and the detected maximum force is the tear force. Tests with a closure for a container according to the invention have shown that the tear force for opening the closure is reduced by for instance 5-15N, when compared with a closure devoid of the stiffening means of the invention requiring an opening tear force of about 40-60N for a 73mm diameter round steel easy opening closure. Essentially is the invention based on the formation of a longer chord (or arc) resulting in a reduction of the opening tear force.
According to a preferred embodiment the score line extends circumferentially along the outer edge of the closure thereby forming a maximal opening in the container and thereby a maximal access to the container content.
Finally, the present invention also relates to a container provided with a closure according to the invention as has been describe as above.
Mentioned and other features and characteristics of a closure and container according to the present invention will be further elucidated and discussed with reference to the following embodiments which are given for information purposes only without an intention to restrict the invention further. In relation to such a description reference will be made to the figures wherein:

Figure 1 shows a perspective view of a closure of the prior art;
Figure 2 is a top view of the closure of figure 1 with the tab and the opening arc;
Figure 3 is the top view of figure 2 without the tab;
Figure 4 is a cross section along the line IV-IV of figure 3;
Figure 5 is a top view of a closure of the invention with the longer opening arc of the invention in comparison to the indicated opening arc of figure 2;
Figure 6 is a top view of the closure of figure 5 without the tab;
Figure 7 is a perspective view of the underside of the closure of figure 5 of the invention;
Figure 8 is a perspective view of the closure of the invention of figure 5 after opening and forming of the opening chord; and
Figures 9-16 are top views according to figure 6 of alternative embodiments of the closure of the invention.

Figure 1 shows a closure 1 of the prior art. The closure 1 comprises a (partially) removable closure part 2 to which is attached a tab 3 via a rivet 4. The closure part 2 has a terrace structure 5 defined by terrace steps 6 and a surrounding substantially circular step 7. The closure part 2 is surrounded by a circular score line 8. Along the score line 8 are extending an outer circular furrow 9 connected to a curl 10 for connection to a container body (not shown), and an inner circular furrow 11 (see figures 2, 3 and 4). The step 7 comprises a curved part 12 thereby providing space for the rivet 4 which is integrally formed from material of the closure part 2. Furthermore, are present dimples 15 supporting the tab 3.
Figure 2 shows the opening chord 16 formed on the folding line 17 when the tab 3 is lifted and the score line broken over the score line arc 18 bounded by the interceptions of the score line 8 with the folding line 17. The tear force for opening the closure 1 when mounted on a container body with a diameter of 73mm is about 45N.
Figures 5-8 show a closure 19 according to the invention. The same structural elements for this closure 19 which are also present and discussed in relation to the closure 1 are identified with the same reference numbers. Closure 19 comprises a closure part 2 to which is attached the tab 3 via the rivet 4. The closure part 2 has a terrace structure 5 defined by the steps 6 and 7. The terrace structure 5 is surrounded by the step 7. The closure part 2 is delineated by the circumferential score line 8. The furrows 9 and 11 extend at each side of the score line around the score line 8. Also present are arced furrows 13 and 14 extending on a hypothetical circle extension of the furrow 7 and laterally of the rivet 4.
The closure 19 according to the invention differs from the closure 1, in that stiffening means 20 extend along the rivet 4 towards the score line 8 thereby stiffening the area 21 laterally of the rivet 4, and in between the rivet 4 and the score line 8. The stiffening means 20 have the form of stiffening grooves 22 extending sidewise of the rivet 4 towards the score line 8 and contact the arc furrows 13 and 14. The effect of the presence of the stiffening means 20 and the form of the stiffening grooves 22 is, that the folding line 23 along which is section 25 of the closure part 2 is folded inwardly after popping and scoring the score line 8 thereby forming an opening 24, is now transferred more towards the center of the closure 19 such that the opening chord 26 defined in between the intersection of the folding line 23 with the score line 8 is larger than the opening chord 16 as discussed in relation to figure 2.
For comparative reasons, is the folding line 17 of the closure 1 as discussed in relation to figure 2 also indicated in figure 5 of the closure 19 according to the invention. It is evident, that due to the presence of the stiffening means 20 in the closure 19 according to the invention, that the folding line 23 is transferred more to the center of the closure 19. Accordingly, the opening chord 26 as defined in between the intersections of the folding line 23 with the score line 8 is longer than the opening chord 16 as defined between the intersections of the folding line 17 with the score line 8. With the result that the tear force for opening the closure 19 when mounted on a container body with the diameter of 73mm is about 36N at about 60µm residual.
Hereafter are discussed various embodiments of the invention showing still other different types of stiffening means 20 according to the invention.
As discussed in relation to the figures 5-8, and further shown in detail in figure 9, the closure 19 according to the invention comprises stiffening grooves 22 extending laterally of the rivet 4 and/or in front of the rivet towards the score line 8, thereby stiffening the area laterally and/or in front of the rivet 4 towards the score line 8. This area is also bounded by the curved step part 12 of the step 7. Figure 9 clearly shows that the stiffening grooves 22 are connected with the arc furrows 13 and 14.
The closure 27 according to the invention as shown in figure 10, comprises the same stiffening grooves 22 according to the invention, but for still further improving the stiffening of the area 21, the arc furrows 13 and 14 have an increased length in comparison to the same arc furrows 13 and 14 as illustrated in figure 9.
The closure 28 according to the invention as illustrated in figure 11 comprises stiffening means 20 which have the form of a curved stiffening groove 34 extending laterally and in front of the rivet 4 and contacts the arc furrows 13 and 14.
The closure 29 according to the invention as illustrated in figure 12 comprises stiffening means 20 according to the invention, having the form of stiffening grooves 35 which extend laterally of the rivet 4 and in front of the rivet 4 but are still laterally in contact with the furrow 11 while passing in between the arc furrow 13 and 14. The skilled person will appreciate, that in an alternative to the embodiment of the closure 29 as shown in figure 12, that the stiffening grooves 25 may also contact the arc furrows 13 and 14. Although the stiffening grooves 35 are indicated as converging to one another in the direction of the score line 8, it will be appreciated by the skilled person that these stiffening grooves 35 may also run in parallel or have a curved or serpentine form.
The closure 30 according to the invention as illustrated in figure 13 comprises stiffening means 20 in the form of stiffening grooves 36 that are connected to the furrow 11, and also arced stiffening groove 37 both partially encircling the rivet 4. In the embodiment of the closure 30 according to the invention it was considered not necessary, although it may be preferred, that the arc furrows 13 and 14 are not present. The skilled person will appreciate that the arced stiffening grooves 37 may also form a single stiffening groove partially or entirely encircling the rivet 4.
The closure 31 of the invention as illustrated in figure 14, shows stiffening means 20 according to the invention which are partially identical to the stiffening means as discussed hereinbefore. The closure 31 comprises arced stiffening grooves 37 and elongated stiffening grooves 38 which are located laterally of the rivet 4. The arced stiffening grooves 37 extend towards the score line 8, but do not connect with the furrow 11. Also for this embodiment of the closure 31 according to the invention, are the arced furrows 13 and 14 not present but could be implemented if so desired in relation to the reduction of the tear force for opening the closure 31.
The closure 32 according to the invention as illustrated in figure 15 also comprises stiffening means 20 according to the invention having the form of the arced stiffening grooves 37 partially encircling the rivet 4. Again it is noted that the stiffening grooves 37 may form one common stiffening groove which partially or entirely encircles the rivet 4.
Finally, shows figure 16 another closure 33 according to the invention which comprises stiffening means 20 according to the invention having the form of stiffening grooves 38 which extend along the rivet 4 towards the score line 8 and are parallel to one another.
After having discussed the various embodiments of the stiffening means 20 according to the invention for an easy opening closure, it will be appreciated to the skilled person that the score line may extend along the circumference of the closure thereby dividing after tearing out the score part 2 the largest opening in the container. However, the score line may also occupy only a part of the closure thereby forming a smaller opening, when the score line is not a closed line only forming an opening as for instance illustrated by the opening 24 as shown in figure 8. Evidently, such closure of the invention may also be present in other types of closures than easy opening closures.
The stiffening means may have the form of stiffening grooves contacting stiffening furrow 13 and 14, and/or contact the furrow 11 extending inwardly of the score line 8 in order to have the desired reduction in tear force for opening the container provided with such a closure of the invention. These furrows 13, 14 and 14 may extend at least partly inwardly (have a concave cross sectional shape) and/or extend at least partly outwardly (have a convex cross sectional shape). Also other types of stiffening structures may be used. Whether or not the various different types of stiffening means may be present, is dependent on the thickness of the closure, of the material of which the closure is made, such as steel, tin plate, aluminum, metal plastic laminates, and the like. Also the diameter of the closure may be taken into consideration, such as diameters varying from 24 to 240mm, such as 40 to 180mm, such as 73mm. Obviously, the presence of step 7 and a terrace structure 5, the presence of dimples and other structures may be taken into consideration by the skilled person when deciding what type of stiffening means 20 according to the invention are to be used in order to reduce the tear force for opening the container while not or substantially not interfering with other structural elements present in the closure.

Claims

Closure for a container, comprising, a tab attached by rivet means to a closure part to be removed for forming an opening in the closure, which opening is defined by a score line formed in the closure, and stiffening means extending along the rivet means towards the score line.
Closure as claimed in claim 1, wherein the stiffening means comprise stiffening bars, stiffening grooves, and the like.
Closure as claimed in claim 1 or 2, wherein at least one furrow extends along the score line and the stiffening means are connected to the furrow.
Closure as claimed in claim 3, wherein the furrow is a circumferential furrow.
Closure as claimed in claim 3 or 4, wherein two circumferential furrows each extends at a side of the score line.
Closure as claimed in claim 3-5, wherein the furrow extends laterally of the rivet means along the score line.
Closure as claimed in any of the claims 1-6, wherein the rivet means are integrally formed from the closure part.
Closure as claimed in any of the claims 1-7, wherein the stiffening means are straight, curved or combinations thereof.
Closure as claimed in any of the claims 1-8, wherein the stiffening means have the form of a groove open to the tab side of the closure part.
Closure as claimed in any of the claims 1-9, wherein an opening chord formed upon opening the closure along the score line is longer than an opening chord formed in a closure devoid of the stiffening means.
Closures as claimed in any of the claims 1-10, having a reduced opening tear force, such as reduced by 5-15N.
Closure as claimed in any of the claims 1-11, wherein the score line extends circumferentially along the outer edge of the closure.
Container provided with a closure according to any of the claims 1-12.