EP0705205A1

EP0705205A1 - Container end

Info

Publication number: EP0705205A1
Application number: EP94918432A
Authority: EP
Inventors: Terence Alexander Benge; Andrew Philip Pavely
Original assignee: CarnaudMetalbox PLC; Metal Box PLC
Current assignee: Crown Packaging UK Ltd
Priority date: 1993-06-24
Filing date: 1994-06-17
Publication date: 1996-04-10
Also published as: GB9524429D0; WO1995000414A1; AU6975094A; ZA944517B; CA2164730A1; GB9313015D0; TW251270B; CN1125926A; JPH08511753A; GB2294022B; MX9404806A; BR9406976A; GB2294022A

Abstract

A container end (20) for delivering a prize (70), when opened, and suitable for use with a beverage container (15), having an end wall (20) made of a metal/polymer laminate. The end wall (20) is fixed to a polymer guide tube (32) by direct moulding, for example, so as to provide an excellent bond between the polymer of the guide tube (32) and the polymer of the end wall (20).

Description

CONTAINER END

This invention relates to a container end and, in particular, to a container end suitable for retaining a gift or prize within a container and guiding the prize out of the container when the end is opened. Containers for holding prizes are known, for example, from WO91/13806 in which an upper part of the container forms a compartment within which a prize may be retained and then ejected by a spring on opening. The lower part of the container is used for retaining a beverage. Another prize-dispensing container is described in US-5046631, in which a guide is provided for retaining a buoyant prize in a beverage adjacent to a closure panel/dispensing aperture.

Further problems can arise if the prize is not guided so as to be ejected satisfactorily from the aperture of the container end once the end is opened. Unless the prize is located beneath the aperture in the end then the prize may jam within the container. This invention seeks to provide a container end which overcomes the above problems.

According to the present invention, there is provided a container end comprising: an end wall of a laminate of sheet metal coated on one side with a first polymer film, comprising a central panel formed with a closure panel defined by a score line; and a guide member made of a second polymeric material for bonding to the first polymer, having an aperture at one end and being fixed to the first polymer side of the end wall with the closure panel overlying the aperture. A problem with known prize containers is that the prize compartment is either seamed together with the container end to a container body, or adhered directly to the container end or body with an adhesive. If a compartment or guide member is seamed together with the end wall, then a product below, such as a beverage, cannot be readily accessed. If an adhesive is used, then such adhesive may be toxic and can contaminate the product or be weakened, so as to compromise the function of the guide member.

Another problem with known containers having a so-called "sealed" compartment, is that the prize can be damaged by liquid ingress, by the beverage or from the atmosphere, since the upper part of the container is not completely sealable and only a small amount of moisture can be tolerated in, for example, a bank note. This problem arises particularly when the prize compartment is made from plastics material which does not adhere satisfactorily to the metal container end.

The use of a laminate to form the end wall, in which the laminate includes a polymer surface which is compatible with the polymer of the guide member enables an excellent bond to be obtained between the end wall and the guide member. A particularly strong and lasting bond can be obtained by direct moulding, induction heating, ultrasonically or friction welding the guide member directly to the laminated end. The bond can thus be obtained without the use of unacceptable adhesives, which might contaminate the beverage in contact with them.

The guide member may be bonded to the underside of an annulus in the end so that the presence of the bond cannot be detected from the "upper" side of the end.

This is particularly a problem with PET laminates where a witness mark can be discerned.

In one embodiment, the guide member may comprise a disc formed with the aperture and a guide tube having an open proximal end which is joined to the disc around at least part of the aperture, the disc being fixed to the end wall. This ensures that a prize within the guide member can be located directly beneath the closure panel of the end wall for ejection. The guide tube may be closed at its distal end and a biasing device inserted within the tube for ejecting the prize. This embodiment is hermetically sealed due to the use of the same polymer for the guide member and laminate.

This enables the two components to be heat sealed together to form a strong bond between thiem. Alternatively, the guide tube may be open at both ends and joined to the disc by a spacer. This form of guide member is particularly suitable if a prize is to be "ejected" by floatation. If the end is connected to a beverage container, for example, beverage is also present within the guide tube and, on opening, a prize contained in a suitably sealed package, will float through the aperture, directed by the guide member.

In a preferred embodiment, the distal end of the guide tube may be constricted so that although liquid can still enter the guide tube, a hydraulic action is achieved. Such action prevents a prize from knocking against the container end as it floats in the beverage. Clearly this knocking is to be avoided where possible as it makes it possible for the presence of a prize to be detected prior to opening the container.

Preferably, the spacer comprises a tubular section connected to the guide tube itself by a flange. The spacer is preferably at least as long as the maximum vertical dimension of the closure panel once opened, so that when the end is opened the closure panel is deflectable past the guide tube, without preventing the prize from being ejected.

If desired, the disc and/or spacer and guide tube may be of different polymers. For example, the spacer or that part of the guide tube which is bonded to the end wall laminate may be polypropylene and the major part of the guide tube may be of PET connected to the polypropylene by mechanical means such as rivets. Although this configuration is more complex than a guide member made of a single material, there are advantages in using polymers which do not affect the taste of certain beverages for the majority of the guide member, whilst using a small amount of a different polymer which provides the best bond characteristics to the laminate of the end. The metal of the laminate of the end wall may comprise aluminium or ferrous material and the first and second polymers may both comprise a polypropylene or polyester film. Alternatively, the polymers may be different but must be compatible to ensure a strong bond. The laminate of metal may be coated on one side by the first polymer and on the other side by a different polymer.

The container end may further comprise a prize package which may be partially retainable within the guide tube but which is reciprocable within the guide tube. In one embodiment, the package comprises a sealed member, mountable within the guide tube. This sealed member may typically comprise a sealed flexible sachet within an open ended component which may be substantially rigid and buoyant. The sachet may be of a foil of other suitable material which prevents liquid/moisture ingress. This is particularly appropriate if the prize is a bank note or other paper product. There should, however, be minimum foil usage so as to avoid pick-up of metal by the beverage. One problem with the use of a sealed member within a a guide tube is that when in the presence of pressurised liquids, the sealed member may distort and become jammed in the guide tube. The use of a flexible sachet which is free to distort within an open ended rigid component which forms part of the prize package prevents such jamming from occurring. Furthermore, retention within the guide tube prevents a consumer of the product from inadvertently swallowing the package.

Preferred embodiments of container end will now be described, by way of example only, with reference to the drawings, in which: Figure 1 is a side section of a container end; Figure 2 is a side section of a container, fitted with the container end of Figure 1 and including a prize. Figure 3 is the side section of Figure 2, with the container end opened;

Figure 4 is a side section of a container, fitted with a second embodiment of container end and including a buoyant prize package; and

Figure 5 is a side section of a container fitted with a third embodiment of container end and including a prize.

In Figure 1, there can be seen a container end 10 comprising an end wall 20 and a guide member 30. The end wall comprises a laminate 40 of aluminium 42 coated on its lower, or inside, surface with a polypropylene film 46. Optionally, the laminate may include further layers, for example it may be coated on its upper surface with a polyester film or include inner layers. It is essential only that the material of the exposed inside surface be the same as or a polymer compatible with the material of the guide member which is to be fixed to it.

A central panel 50 of the end wall 20 is formed with a closure panel defined by a score line 54. The closure panel is permanently connected to the central panel by a bendable region (not shown) so that, when opened, the closure panel remains connected to the central panel 50 and depends vertically into a container from it. A tab 60 is riveted to the end wall adjacent to the closure panel for opening the end. The guide member 30 comprises a guide tube 32, open at both ends and having a flange 34 extending from one portion of its upper end. At the upper end of the guide member, a disc 36 is provided for connecting the guide member to the end wall 20. The disc is spaced from the guide tube itself by spacer 38, which extends between the disc and the flange 34. The disc 36 has an aperture 37, direσtly above the guide tube. Optionally, strengthening ribs may be provided on the polypropylene disc.

The guide member 30 is made from polypropylene and is heat sealed to the polypropylene side 46 of end wall 20, with the closure panel 54 of the end wall positioned over the aperture 37 of the guide member.

Figure 2 shows the container end fixed to a container 15 with a prize 70 inserted within the guide tube 32. The laminate end wall has been shown as a single layer for the sake of clarity only. The container 15 is filled with a product such as a beverage 75 which is also present in the guide tube 32, so that the prize 70, here shown as a package, floats within the guide tube and bears against the closure panel 56 of the end wall. In Figure 3, the container of figure 2 is opened so that the closure panel 56 has been pushed into the container by lifting the tab 60. The prize thus floats in its equilibrium position, out of the container, as shown. To open the container, the tab is raised so that the panel moves into the container body, pushing the prize 70 down into the beverage until the tab is raised towards the vertical position. As the tab is raised, the closure panel 56 deflects the prize until the panel passes the open end of the guide tube, opposite the spacer 38. The prize is then free to float in the beverage once more. Since the closure panel no longer impedes movement of the prize, the prize floats in the beverage, through the two apertures 37 and 52.

The prize package may be buoyant either by use of a buoyant container as described below with reference to figure 4, or by the addition of a buoyant material such as cork or expanded polystyrene. Clearly many alternatives are available for achieving this.

Figure 4 shows a second embodiment of container, in which the spacer 138 comprises a cylindrical section of larger diameter than the guide tube 132 connected to the end via a flange around disc 136. The guide member 130 is thus more readily moulded in a single piece. The disc flange is sealed to an annulus around the edge of the end so as to avoid a witness mark in which the presence of the heat seal bond could be detected from outside the container, thus indicating that the container includes a prize.

The guide tube 132 includes an inwardly directed flange 133 at its lower end, which serves to co-operate with an outwardly directed flange 173 on a prize package 170, so as to prevent the package from falling out of the guide tube 132, particularly during assembly. A further inwardly directed flange 135, at the upper end of the guide tube, also co-operates with flange 173 and prevents the package from inadvertent consumption with the beverage 175.

The prize package 170 comprises a sealed foil sachet 172 which contains a bank note, for example, and an open-ended tubular component 174. Component 174 is generally rigid but with a little resilience to enable it to be loaded into the guide tube 132 and snap past flange 133 and also to be removed from the container, past flange 135 of the guide tube. Typically, the component 174 is of buoyant material, such as polypropylene, polythene or any suitable non-toxic material which has a density of less than 1.

This embodiment uses an open-ended component 174 together with a sealed sachet 172, so that pressure due to carbonated beverages, for example, only affects the sachet, the component 174 being unaffected due to pressure equilibrium from beverage both within and outside of the open-ended component. However, a simple sealed package could be used to replace both component 174 and the sachet 172 provided that the sealed package is sufficiently strong and rigid to withstand the external pressure without distortion. To assemble a prize container, a laminate end wall 120 and guide member 130 are first bonded together. A convenient bonding method is by induction heating but strong bonds have also been achieved using direct moulding, ultrasonic welding or hot melt adhesive. For direct moulding, rivets are moulded onto the end wall 120 which locate with holes in the disc part 136 of the guide member 130. Bonding by induction heating is particularly fast as can be seen from the example below. A bank note is sealed within an aluminium foil sachet 172 and the sachet folded as necessary so as to be inserted within tubular component 174 and to minimise metal exposure. This component is pushed through the lower end of the guide 132, past the flange 133. A unitary container end 110 is then available for seaming to a container body 115 in the conventional manner after filling the container with the desired beverage.

The prize package 170 floats within the beverage 175 and any distortion due to pressurisation of the beverage affects only the sachet 172, the component 174 being open at both ends and substantially rigid. Jamming of the package 170 within guide tube 132 is thus avoided. Usually, the prize package 170 includes some compressible material at its upper end which provides damping of any impact of the package against the end wall 120. This renders it difficult to detect the presence of a prize package within the container which might otherwise be apparent if the package knocks against the end as it floats within the beverage in a reciprocating manner, limited from lateral movement by the guide member.

The guide tube 132 may also be of smaller internal diameter at its lower end so as to produce a hydraulic action and prevent knocking of the prize.

The use of induction heating to bond the polymeric guide member to the laminate end wall is significantly better than the use of for example an epoxy adhesive. Not only are such adhesives subject to stringing and the risk of debris contaminating the beverage, but the epoxy may take as long as a week to cure satisfactorily. Furthermore, the strength- of the bond achievable with a heat seal bond is greater than is possible for an epoxy resin. The following example relates to an evaluation of bond strength of the guide member to the container end of the present invention.

Example

It was required to measure the bond strength of the guide member to the end under various sealing conditions and to compare different resins used for moulding the device. Five different resins were used in the moulding of the devices and these are described as follows:

A) Neste XC 1275 DNA Random copolymer of polypropylene.

B) Hi ont EPH 3IRA block copolymer of polypropylene. C) DSM 312 N40 block copolymer of polypropylene.

D) DSM 412 MN40 block copolymer of polypropylene.

E) DSM 112 MN40 homopolymer of polypropylene. The sealing was conducted with an induction heater and seals were made under a variety of seal time and voltage settings so that a matrix of different seal conditions was evaluated. Two samples were prepared for each condition and one sample was seamed to a can filled with Coca Cola (registered trade mark) and stored at 38°C for 1 month. The other sample was retained in a laboratory at 23°C and 50% relative humidity (R.H) for the same length of time. At the time of sealing, the end was examined to see if the sealing conditions had caused melting and distortion of the surface adjacent to the seal. After storage the filled cans were emptied and acclimatised to 23°C at 50% R.H. Both sets of cans were then tested for seal strength. This was achieved by use of the Instron tensometer with a specially made probe that could be pushed through the ring pull opening on to the guide member while the can was resting on the compression load cell. The probe was lowered at 50mm/min and the peak force reading was taken as the seal strength.

Conclusions

The following points can be deduced from the results:

Cans stored empty at ambient conditions

Use of power setting of less than 850 volts required significantly longer sealing times, whereas above this threshold increasing power only slightly improved the bond.

There was a limitation on the power and/or the sealing time that could be used without damaging the polypropylene surface of the end. This damage would result in the exposure of aluminium to the product.

The fact that the damage tended to be in a localised area suggests that it may be possible to improve the resistance of the end to damage by optimisation of the sealing head. A sealing force of 200N can be achieved at an 850 volt setting, without damaging the end by using the following ranges of sealing times:

Resin Sealinq ranqe (seconds)

A) Neste XC 1275 DNA 3.8-4.1

B) Himont EPH 31RA 3.9-4.1

C) DSM 312 MN40 3.9-4.1

D) DSM 412 MN40 3.7-4.1

E) DSM 112 MN40 4.1-4.1

As would be expected the upper limit is independent of the guide member polymer. The DSM 112 MN40 is the least tolerant and the DSM 412 MN40 the most tolerant. The limitation on the failure of the bond was imposed by the cohesive strength within the guide member as the high bond strengths involved the fracture of the moulding.

Cans stored filled at 38°C

The existing DSM 112 homopolymer has the worst bond and the XC1275 has the best bond.

It can thus be seen that bond strengths of 200N can be achieved by an induction heat seal bond which is obtained after only a few seconds. Clearly this offers significant advantages over alternative bonding methods such as epoxy adhesive.

Figure 5 shows an alternative embodiment of container end 210 in which the guide tube 232 is fixed directly to the disc 236 and is sealed at its lower end 233. A prize 270 contained in the guide tube is thus protected from attack or contamination by the product 275 because the guide tube is hermetically sealed to the end wall 220 of the container end 210 by heat sealing.

A biasing device 280 included in the guide tube ejects the prize from the container on opening. The prize need not be separately packaged in any way since the guide member 230 and end wall 220 prevent penetration of the product into the tube.

Generally, this embodiment of container end would be used with a pull-off tab so that the closure panel 256 does not impede the passage of the prize through the apertures.

Claims

1. A container end comprising: a end wall of a laminate of sheet metal coated on one side with a first polymer film, comprising a central panel formed with a closure defined by a score line; and a guide member made of a second polymeric material for bonding to the first polymer, having an aperture at at least one end and being fixed to the first polymer side of the end wall with the closure panel overlying the aperture.

2. A container end according to claim 1, in which the guide member comprises a disc formed with an aperture and a guide tube having an open end which is joined to the disc around at least part of the aperture, the disc being fixed to the end wall.

3. A container end according to claim 1 or claim 2, in which the guide member is closed at its distal end.

4, A container end according to claim 2, in which the guide tube is opened at both ends and joined to the disc by a spacer.

5. A container end according to claim 4, in which the spacer is at least as long as the maximum dimension of the closure panel.

6. A container end according to any one of claims 1 to

5, in which the metal of the laminate of the end wall comprises aluminium or ferrous material.

7. A container end according to any one of claims 1 to

6, in which the first polymer comprises a polypropylene or polyester film.

8. A container end according to any one of claims 1 to 7, in which the end wall comprises a laminate of metal coated on one side by the first polymer and on the other side by a second polymer.

9. A container end according to any one of claims 4 to 8, further including a prize package comprising a sealed flexible sachet within an open ended substantially rigid and buoyant component.

10. A container comprising a container body and the container end of any one of claims 1 to 9, including a prize package.