GB1567368A

GB1567368A - Containers having tear off aluminium foil covers

Info

Publication number: GB1567368A
Application number: GB2187377A
Authority: GB
Original assignee: Alcan Research and Development Ltd
Current assignee: Alcan Research and Development Ltd
Priority date: 1976-05-25
Filing date: 1977-05-24
Publication date: 1980-05-14
Also published as: DE2719232A1; ES233482Y; CH612140A5; ES233482U

Abstract

A container (1) is covered by a foil (2) made of aluminium or an aluminium alloy of a hardness of 35 to 45 micro-Vickers, the edge (8) of which foil is bent around an edge flange on the container. The bending radius r is not larger than 2 mm. This has the consequence that a tear line (7) is formed along the point of the largest bend without it being necessary to provide embossed lines for this purpose. The container can be opened by hand along this tear line by means of a tear-off tab attached to the edge of the foil. <IMAGE>

Description

(54) IMPROVEMENTS RELATING TO CONTAINERS HAVING TEAR-OF ALUBIUM FOIL COVERS (?i} We, ALCAN RESEARCH AND DE VELOpraENT LIMITED, a Company incor- porated under the laws of Canada, of 1 Place Ville Marie, Montreal, Quebec, Cantia, do hereby declare the invention, for which we pray that a patent may be granted to us, and the method by which it is to be performed, to be particularly de scribes in and by the following state ment This invention relates to containers having tear-off aluminium foil covers.

According to the invention there is provided a container having an aluminium foil cover made from a + to 3-hard alumi fliwn ar aluminium alloy, the edge of the cover being bent around the rim of the container and having at least one tear-off tab and a tear-initiating configuration adpining the or each tear-off tab which configuration extends from the edge of the cover and terminates at the adjacent bend of the bent-over edge of the cover, the radius of said bend being selected to cause the tab, when pulled, to tear the cover along the bend, so that a marginal portion of the cover is torn off with the tab.

The invention will now be described in greater.detail with reference to the attached diagrammatic drawings illustrating some forms of construction. In the drawings: Figure 1 is a perspective view of a rectangular container having a cover provided with a tear-off closure means in accordance with the invention; Figure 2 is a perspective top view of a container having a cover with a tear-off closure means in accordance with the invention; Figure 3 is a plan view of part of a cut .blank for forming a cover, two tear-off tabs formed in accordance with the invention being illustrated;; Figures 4a to 4d are diagrammatic sec tional views illustrating the important steps in the manflfacture of a cover and in the airtight fitting of this cover on to a container, the tear-off tabs being omitted from these Figures so as to make them clearer; and Figures 5 to 7 are side views of parts of a number of containers provided with a cover, these views illustrating modified forms of the tear-off tab and of the tearinitiating configuration in accordance with the invention.

For the sake of simplicity, those parts that perform the same function are each designated by the same reference numeral in the various Figures even if these parts differ from each other in their shaped In the drawings, the reference numeral I designates a container and the reference numeral 2 a cover. In the Figure 1 arrangement, the container 1 is approximately rectangular and has rounded corners. A tear-off tab 3 projects from each of three of the four edges of the cover 2. These tear-off tabs 3 are shaped like fins and are designed to be pulled to the left along the two sides visible in Figure 1.The righthand side 4 (as seen in Figures 1, 2 and 5 to 7) of each tab runs to the edge of the cover 2 at a wide angle, whereas the lefthand side of each tab curves gently towards the edge of the cover over a large radius R (best seen in Figures 3 and 6) or runs towards said edge at a slight angle.

A tear-initiating configuration 6 is-formed in the zone where the right-hand edge 4 of each tag joins the edge of the cover2. The inner end of each configuration 6 is located on a line 7 formed by dots and dashes in the drawing. This line represents the zone of maximum curvature of the turned-over edge 8 of the cover. The radius of curvature along this line is designated r (Figures 4d, 5 and 6).

To ensure that tearing occurs along the chain line 7, the cover is made from an aluminium foil preferably of 992% pure aluminium, + to ;shards i.e. having a hardness of 35 to 45 micro-Vickers units,-and having a thickness of between 40 and 60 pm. It has been found that if the aluminium material of the cover 2 is softer, tearing along a specific line, i.e. along the chain line 7, cannot be achieved without the help of indentations, whereas an aluminium material which is too hard cannot be manipulated, because of its excessive brittleness, and breaks.

A further important factor in ensuring that tearing occurs along the line 7 is the correct selection of the radius r of bend of the edge 8 which is turned over round the rim 9 of the container (Figure 4d).

This radius of bend is preferably within the range 05-2mm.

Tearing in the correct direction is promoted by the orientation of the tear-initiating configuration 6. In all the embodiments, this configuration is directed towards line 7 at a slight angle. In the arrangements shown in Figures 1 and 2, the tearinitiating configuration consists of a notch formed in the edge 8 of the cover 2 immediately to the right of the tear-off tab 3.

In the variants shown in Figures 5 and 6, the notch 6 also runs into the tear-off tab 3, and it is deeper in the arrangement of Figure 5. In the arrangement illustrated in Figure 7, the tear-initiating configuration is formed by an inclined folded line 6' which extends obliquely from the point of intersection of the right-hand edge 4 of the tab 3, and the edge 8 of the cover 2 to the line 7 of maximum curvature.

For the purpose of opening the tear-off closure means illustrated in Figure 1, pull is applied to each of the side edges in the direction indicated by the arrows by means of a tear-off tab 3. Surprisingly, the material of the cover 2 then divides along the chain line 7 without it having been necessary to provide indentations or the like along this line. No tear-off tab 3 is provided on that narrow side of the container that cannot be seen in Figure 1. In the arrangement illustrated therein, the cover, separated from the three other sides of the container, has to be swung up like a trapdoor in order to open the container fully.

The cover can then either be removed from the container 1, or, if only part of the contents of the container are removed, the cover can remain on the container and can be pressed down again on to it so as to protect its contents In the arrangement shown in Figure 2 wherein a round container 1 is used, the cover is opened by exerting null, along the line 7, on the single tear-off tab 3 that is provided In both cases the line 7 is so located that even when the tear-off tabs and the strips of material attached thereto have been completely removed, the remaining inner portion of the cover projects beyond the uncovered container opening so that even after the cover has been completely detached, the remaining portion can still be used for temporarily covering the contents of the container for the purpose of keeping them fresh, etc.

Figure 3 is a plan view of a blank for forming the cover 2 prior to its having been subjected to any bending operation. Figure 4a is a side view of the cover in this condition, the tear-off tabs not however being illustrated so as to make the subsequent Figures 4b to 4d clearer.

These further Figures illustrate steps in the establishment of a connection between the cover 2 and the container 1. Figure 4b shows how the cover is bent over and downwards along a line 10 so that a peripheral dependent edge 8 is formed. The bend is made through an angle of 90". Figure 4c illustrates diagrammatically how the cover, pre-shaped as in Figure 4b, is placed on the peripheral rim 9 of the container 1.

In the next step, the edge 8 is turned over and down around the rim 9 by means of a sealing machine and as shown in Figure 4d, the radius r of bend being formed.

Thus, surprisingly simply because of the proposed choice of material and radius of bend, a well-defined tear becomes possible at the zone of maximum curvature, located roughly at the middle of the edge turned over around the rim of the container, without the need for special indentation lines, which are expensive to provide. The cover can be rapidly, cleanly and completely removed from the container without any portions of the cover remaining on the container and without the fingers coming into contact with the contents of the container.

WHAT WE CLAIM IS: - 1. A container having an aluminium foil cover made from a W to -43-hard aluminium or aluminium alloy, the edge of the cover being bent around the rim of the container and having at least one tear-off tab and a tear-initiating configuration adjoining the or each tear-off tab which configuration extends from the edge of the cover and terminates at the adjacent bend of the bent-over edge of the cover, the radius of said bend being selected to cause the tab, when pulled, to tear the cover along the bend, so that a marginal portion of the cover is torn off with the tab.

2. A container according to claim 1, wherein the thickness of the aluminium foil of the cover is in the range 40 to 60 ym.

3. A container according to claim 1 or c'aim 2, wherein the tear-initiating configuration extends in the direction in which pull is applied along the bend but at an acute angle to said bend.

**WARNING** end of DESC field may overlap start of CLMS **.

Claims

**WARNING** start of CLMS field may overlap end of DESC **. pm. It has been found that if the aluminium material of the cover 2 is softer, tearing along a specific line, i.e. along the chain line 7, cannot be achieved without the help of indentations, whereas an aluminium material which is too hard cannot be manipulated, because of its excessive brittleness, and breaks. A further important factor in ensuring that tearing occurs along the line 7 is the correct selection of the radius r of bend of the edge 8 which is turned over round the rim 9 of the container (Figure 4d). This radius of bend is preferably within the range 05-2mm. Tearing in the correct direction is promoted by the orientation of the tear-initiating configuration 6. In all the embodiments, this configuration is directed towards line 7 at a slight angle. In the arrangements shown in Figures 1 and 2, the tearinitiating configuration consists of a notch formed in the edge 8 of the cover 2 immediately to the right of the tear-off tab 3. In the variants shown in Figures 5 and 6, the notch 6 also runs into the tear-off tab 3, and it is deeper in the arrangement of Figure 5. In the arrangement illustrated in Figure 7, the tear-initiating configuration is formed by an inclined folded line 6' which extends obliquely from the point of intersection of the right-hand edge 4 of the tab 3, and the edge 8 of the cover 2 to the line 7 of maximum curvature. For the purpose of opening the tear-off closure means illustrated in Figure 1, pull is applied to each of the side edges in the direction indicated by the arrows by means of a tear-off tab 3. Surprisingly, the material of the cover 2 then divides along the chain line 7 without it having been necessary to provide indentations or the like along this line. No tear-off tab 3 is provided on that narrow side of the container that cannot be seen in Figure 1. In the arrangement illustrated therein, the cover, separated from the three other sides of the container, has to be swung up like a trapdoor in order to open the container fully. The cover can then either be removed from the container 1, or, if only part of the contents of the container are removed, the cover can remain on the container and can be pressed down again on to it so as to protect its contents In the arrangement shown in Figure 2 wherein a round container 1 is used, the cover is opened by exerting null, along the line 7, on the single tear-off tab 3 that is provided In both cases the line 7 is so located that even when the tear-off tabs and the strips of material attached thereto have been completely removed, the remaining inner portion of the cover projects beyond the uncovered container opening so that even after the cover has been completely detached, the remaining portion can still be used for temporarily covering the contents of the container for the purpose of keeping them fresh, etc. Figure 3 is a plan view of a blank for forming the cover 2 prior to its having been subjected to any bending operation. Figure 4a is a side view of the cover in this condition, the tear-off tabs not however being illustrated so as to make the subsequent Figures 4b to 4d clearer. These further Figures illustrate steps in the establishment of a connection between the cover 2 and the container 1. Figure 4b shows how the cover is bent over and downwards along a line 10 so that a peripheral dependent edge 8 is formed. The bend is made through an angle of 90". Figure 4c illustrates diagrammatically how the cover, pre-shaped as in Figure 4b, is placed on the peripheral rim 9 of the container 1. In the next step, the edge 8 is turned over and down around the rim 9 by means of a sealing machine and as shown in Figure 4d, the radius r of bend being formed. Thus, surprisingly simply because of the proposed choice of material and radius of bend, a well-defined tear becomes possible at the zone of maximum curvature, located roughly at the middle of the edge turned over around the rim of the container, without the need for special indentation lines, which are expensive to provide. The cover can be rapidly, cleanly and completely removed from the container without any portions of the cover remaining on the container and without the fingers coming into contact with the contents of the container. WHAT WE CLAIM IS: -

1. A container having an aluminium foil cover made from a W to -43-hard aluminium or aluminium alloy, the edge of the cover being bent around the rim of the container and having at least one tear-off tab and a tear-initiating configuration adjoining the or each tear-off tab which configuration extends from the edge of the cover and terminates at the adjacent bend of the bent-over edge of the cover, the radius of said bend being selected to cause the tab, when pulled, to tear the cover along the bend, so that a marginal portion of the cover is torn off with the tab.

4. A container according to any one of

claims 1 to 3, wherein the tear-off tab is shaped like a fin.

5. A container according to claim 1 or claim 2, wherein the tear-initiating configuration is formed by a notch extending at an acute angle to the line of the bend.

6. A container according to claim 1, wherein the side of the periphery of the tear-off tab at which the tear-initiating configuration is provided joins said edge of the cover at a steep angle, and the other side of the periphery of the tab merges gently with said edge, the portion of the periphery of the tab between said two sides being rounded.

7. A container as claimed in any one of claims 1 to 6 and in the form of a polygon having n-corners wherein a tear-off tab is provided on each of at least n-l sides of the edge of the cover, and is disposed at one end of such side.

8. A container as claimed in claim 7, wherein all of the tear-off tabs are provided at corresponding ends of the respective sides so that pull can be applied to all the tearoff tabs in the same direction.

9. A container as claimed in any one of claims 1 to 6 wherein the container is circular and only one tear-off tab is provided.

10. A container as claimed in any one of claims 1 to 9, wherein the foil for forming the cover is made from 992% pure aluminium.

11. A container as claimed in any one of claims 1 to 10, wherein the radius of said bend is in the range 05 to 2mm.

12. A container substantially as hereinbefore described with reference to and as illustrated in Figures l, 3 and 4a to 4d or in Figures 2 and 4a to 4d, or in any one of Figures 5 to 7 of the accompanying drawings.