GB2142911A

GB2142911A - Sealing containers

Info

Publication number: GB2142911A
Application number: GB08318155A
Authority: GB
Inventors: Walter Karl Hettich
Original assignee: HETTICH PLASTICS Ltd
Current assignee: HETTICH PLASTICS Ltd
Priority date: 1983-07-05
Filing date: 1983-07-05
Publication date: 1985-01-30
Also published as: GB8318155D0; GB2142911B

Abstract

In a container having a cap and having, beneath the cap, a pilfer- indicating membrane sealed across the mouth of the container, usually applied by induction heating with the cap already in place and pressing the membrane onto the neck, opening of the membrane is facilitated by providing a tab or flap (T) which extends beyond the rim of the neck but which is concealed by the cap (C) when the cap is in place. In addition there is a line of perforations around the membrane in the region overlying the rim, with a gap to form a hinge line, and the underside of the cap has a channel (G) over the line of perforations to avoid applying pressure in this region. <IMAGE>

Description

SPECIFICATION Sealing containers This invention relates to the sealing of containers, such as bottles, flasks or similar bodies having a necked opening, by the provision of a diaphragm, sealed to the rim of the opening in addition to the provision of the usual screw-on or snap-on cap.

Such a sealing arrangement has the merits of keeping the contents of the container completely airtight during shipping and storage until first use, without having to rely on the airtightness of the snap-on or screw-on cap, but in addition can have the function, often even more important, of "tamper-evidence", that is to say, of showing the purchaser, when he first takes off the cap, that the contents have not been tampered with.

It is known to apply such a seal simultaneously with the cap by making the wad or liner of the cap of a laminated material of which one layer forms the ordinary liner that remains with the cap in use whilst another layer, separated from the liner by an easily separated layer, e.g. of wax, is of, for example, aluminium foil to form the sealing diaphragm and it has a coating of thermoplastic material on its underside, at least around its peripheral region. After capping, the container is passed under an electric induction heating system that softens the thermoplastic layer and causes it to seal the aluminium foil to the rim of the neck.

The known seals have certain drawbacks.

When the user opens the container he usually ruptures the seal with a thumb or forefinger.

This gives rise to a serious danger of contamination, either of the contents from the finger or if, the contents are of a poisonous or corrosive nature, of the finger from the contents. Second, the rupturing leaves a jagged edge, with part of the foil still present making smooth pouring impossible. Third, the user often tries to improve things by tearing at the remaining foil, giving rise to further danger of contamination and also the pieces which he detaches will contaminate the surroundings.

The main aims of the invention are therefore to provide, for a capped container, a tamper-evident sealing system which is easy to open without rupturing the membrane, which leaves a clear opening free from jagged edges or obstructions, and which preferably leaves the membrane attached to the container so that it is not discarded to poliute the surroundings.

According to the invention we propose that such a membrane should include a tab or flap, to be grasped by the user, which extends laterally beyond the rim of the bottle and there is in the membrane a line of perforations or of weakening which extends circumferentially around that region of the membrane which overlies the rim, this line being omitted over a limited arcuate region opposite the tab to form a retaining hinge. The cap is designed so that it does not apply pressure to the region of the line of weakening, so that adhesion does not take place in this region in the induction heating step and the same applies to the region between this line and the tab.

After removing the cap, the user can then open the tamper-evident seal by grasping the tab and pulling upwards, without soiling his hands, whereupon the diaphragm will tear at the line of perforations or weakness but will remain attached to the container neck by the hinge line. However, if desired, a stronger pull will allow it to be detached altogether in one single piece for disposal.

The opening which is left is free from obstruction, since the line of perforations is radially outwards of the inner periphery of the rim.

In the case of a circular opening, the hinge line may extend over, say, thirty degrees of arc opposite the tab.

The cap must be designed to provide clearance in the form of a nest or recess to receive the tab.

According to a further feature of the invention the laminate that forms the combined cap liner and sealing diaphragm includes an additional layer of absorbent material associated with the wad in order to absorb the wax (which softens or melts in the induction heating step) and thereby prevent the wax damaging the wad itself or, at a later time, the contents of the container. As will be seen from what follows, the laminate may have eight layers altogether including the adhesives.

The invention will now be further described by way of example with reference to the accompanying sketches, in which: Figure 1 is a plan view of the diaphragm on the neck of a container; Figure 2 is a simplified cross-section through the neck, with the cap, wad and diaphragm in place;, Figure 3 is an exploded view of the combined wad and diaphragm; Figure 4 illustrates how the laminate is stamped out to form the wads.

In Figure 1 the inner and outer circles represent the inside and outside peripheries of the neck of a container. The aluminium foil diaphragm is of a diameter equal to the outside diameter of the neck, and has a thermoplastic adhesive over at least the crosshatched area; the nature of the adhesive is chosen to suit the material of the container, e.g. polyester or polyethylene. A line of perforations as shown is near the inner periphery, but there is a gap over an arc of about 30 to form a hinge line and, diametrically opposite this, the line extends out to the periphery of the diaphragm at opposite sides of a laterally extending tab T.

As shown in Figure 2 the cap C, on being fitted, clamps the diaphragm against the neck of the container but there is an annular groove G in the cap, aligned with the line of perforations in the foil, so that there is no pressure in this region and when the capped container passes through the induction heater (not shown), this region of the diaphragm does not become welded to the container neck. Also to be observed in Figure 2 is an annular recess or nest N in the cap which provides clearance for the tab T on the foil.

Figure 3 shows the eight layers of the laminate. The total is arranged in two multilayers P and A. These are held together by a layer 4 of wax which forms the release agent and which is mopped up by the paper layer 5 when undergoing the heating process. The multi-layer P consists of pulp 1, glue 2 and PET foil P, whilst the multi-layer A consists of paper 5, glue 6, aluminum foil 7 and lacquer 8, which acts as a thermoplastic seal and, in this example, extends over the whole area.

In the manufacture of wads from the laminate the first operation in a progressive tool is the cutting of layer 8 through to layer 5 inclusive to provide the lines of perforations and the outline of the tab T. The second is a cut made from the other side through layers 1 to 3 inclusive, between the tab and the rest of the blank. The third operation is the stamping out of the waste material around the final product. By this step the portion of multi-layer P beneath the tab will be drawn away from below the tab and at the same time the tab itself will be pulled down into a position approximately at right angles to the plane of the blank. This position allows the tab to curl into the nest on the cap when the wad is assembled into the cap.

The final position of the tab T in the nest N ensures that the tab is not inadvertently welded to any of the plastics components during the welding process. Although, because the nest N extends all round the cap, no orientation of the wad with respect to the cap is necessary, however it is desiråble to orientate the wad during assembly of the wad into the cap in order to achieve a constant position of the tab T in relation to the position on the container, so as to allow the most effective pouring direction.

Finally the cap is applied to the container, which is passed through an induction heater that softens the layer 8 to weld the aluminium foil to the neck of the container (except along the line of perforations and under the tab); at the same time the wax is absorbed by the paper, releasing the wad from the diaphragm, so that when the user first unscrews the cap the wad remains within the cap.

Claims

1. A container and cap assembly having a sealing membrane sealed across the mouth of the container beneath the cap, in which the membrane includes a tab or flap, for grasping by the user, which extends laterally beyond the rim of the mouth of the container and there is in the membrane a line of perforations or other weakening which extends circumferentially around that region of the membrane which overlies the rim of the neck, this line being omitted over a limited arcuate region opposite the tab to form a retaining hinge.

2. An assembly according to claim 1 in which the line of perforations or other weakening extends to the outer periphery of the membrane at each side of the tab or flap.

3. An assembly according to claim 1 or claim 2 in which the underside of the cap, where it engages the membrane when the cap is in place on the sealed container, has a channel-like recess in the region of the perforations or other line of weakening so that the cap does not apply pressure to the membrane in this region.

4. An assembly according to any one of claims 1 to 3 in which the cap has a skirt which engages the outside of the container around the rim of the mouth and conceals the tab or flap of the membrane, and in which the inside of the skirt has a nesting recess formed in it to provide clearance for the tab or flap.

5. An assembly according to claim 4 in which the neck is circular and in which the nesting recess extends all the way round the inside of the skirt of the cap so that the relative orientation of the cap and member is immaterial.

6. An assembly according to any one of claims 1 to 4 in which the neck is circular and in which the retaining hinge extends over an arc of substantially 30 .

7. An assembly according to any one of claims 1 to 6 in which the membrane is part of a multi-layer laminate which also forms a cap liner or wad that remains with the cap when the cap is removed from the container, the laminate including a release layer of wax between the cap liner or wad and the membrane and an additional layer of absorbent material between the wax and the membrane to absorb the wax when it is melted by heat applied during the sealing of the membrane onto the neck of the container.

8. A container and cap assembly substantially as described with reference to Figures 1 and 2 of the accompanying drawings.

9. A container and cap assembly according to claim 8 including the further features substantially as described with reference to Figure 3 of the accompanying drawings.