The present invention relates generally to a seal for a container and particularly to a seal which is intended to be pierced in order to allow access to product in a container.

It is known to provide container seals for preserving the contents of the container prior to opening. In many cases the seal is pierced to gain access to the product. When the seal is pierced the material of the seal may come into direct contact with the product. Depending on the type of seal there may be certain layers which must be present in order to provide it with certain properties, such as the ability to be seal to the rim of the container and the ability to prevent ingress and or egress of material to and from the product. These requirements may conflict with the desire to avoid contact of certain materials in the seal with the product.

The present invention seeks to address the problems with known container seals. According to a first aspect of the present invention there is provided a pierceable, induction sealable seal for a container opening, the seal comprising a plurality of layers at least one of which is metallic and at least one of which is non-metallic, at least one of the non-metallic layers is complete and in use extends across a container opening to seal it, in which the area over which the or at least one of the metallic layers extends is restricted to the region of the periphery of the seal whereby to facilitate induction sealing to the opening but to remain isolated from product in a container upon piercing of the seal.

By having one or more layers with incomplete coverage the material from the seal which is torn and pushed down during piercing can be controlled. Therefore material which may be incompatible with a product in a container can be present but isolated from the product following piercing. One of the layers is complete. In other words, the layer may extend over substantially the entire area of the seal when viewed in plan or at least over the entire area of a container opening.

The restricted layer/s may be restricted to the region of the periphery of the liner. This is particularly useful where the layer/s are involved in fixing the seal to a container rim and/or sealing because they may only be required at the periphery.

The restricted layer/s may be formed as an annulus. The annulus may therefore define a piercing zone at its centre which does not include any material from the restricted layer/s.

The seal may include a layer of polyethylene terephthalate (PET). The layer of PET may be complete. The liner may include a layer of aluminium. Aluminium or a similar conductive material may be required for certain applications, such as when the seal will be induction welded to the container rim. The layer of aluminium may be incomplete.

The seal may include a layer of foam such as foamed polyethylene or polypropylene. The layer of foam may be incomplete.

The layers may be secured to each other by adhesive, wax or the like. In use one or more of the layers may separate from each other. For example, some layers may remain on a container and other may be retained in an associated closure.

The seal may be formed as a liner for a container closure. The closure may be a self- piercing closure, with a mechanism for piercing through the seal. The seal may be formed as an induction seal liner, for example a heat induction sealed liner.

According to a further aspect there is provided a seal as described herein in combination with a container.

According to a further aspect there is provided a seal as described herein in combination with a closure. The closure may be a self-piecing closure. The present invention will now be more particularly described, by way of example, with reference to the accompanying drawings, in which:

Figure 1 is a section of a seal formed according to an embodiment of the present invention;

Figure 2 is a bottom perspective view showing the underside of the seal of Figure 1 ;

Figure 3 is a section of the seal of Figure 1 and 2 shown fitted into a closure as a liner; Figure 4 is a section of the closure/seal of Figure 3 shown attached to a container neck;

Figure 5 is a section of the closure/seal/container of Figure 4 following first removal of the closure; Figure 6 is a section of the container/seal of Figure 6 following piercing of the seal;

Figure 7 is a side elevation of a seal formed according to an alternative embodiment of the present invention; Figure 8 is a top perspective view of the seal of Figure 7;

Figure 9 is a side view of the seal of Figure 7 and 8 shown attached to a container neck rim;

Figure 10 is a partial section of the seal of Figure 9 shown following piercing;

Figure 1 1 is a partial section of a closure incorporating a liner formed according to the present invention;

Figure 12 is a perspective section of the closure of Figure 1 1 ;

Figure 13 is a further section of the closure of Figure 12; Figure 14 is a section of a body part of the closure of Figure 1 1 shown in an unactivation position; and

Figure 15 is a section of the part of Figure 14 shown in an activated position. Referring first to Figure 1 there is shown a disc-shape seal generally indicated 10. The seal 10 comprises a layer of polyethylene terephthalate (PET) 20 and a layer of foam 30 secured to each other by a layer of adhesive 40.

The PET layer 20 is complete, in other words it extends completely over the area of the seal in plan. The foam layer 30 is formed as an annulus secured to the underside of the PET layer. Accordingly the layer 30 is incomplete and defines a central region 22 of the PET layer over which the foam layer 30 does not extend. Referring now to Figure 3, the seal 10 is shown to be formed as a liner and 10 is secured into the top of a closure generally indicated 50. The closure 50 comprises a disc-shape top plate 60 with a cylindrical skirt 70 depending from the periphery thereof. The skirt 70 includes screw thread formations 80. The seal 10 is weakly adhered to the underside of the top plate 60 by an adhesive layer 15 on top of the PET layer 20.

In Figure 4 the closure 50 is shown applied to a container neck 90. The closure is applied using screw thread formations 95 on the neck corresponding to the formations 80 on the closure.

To secure the seal 10 to the container rim 97 heat curable adhesive 25 is applied to the rim before application of the closure. Subsequently heat is applied to the top plate 60 to cure the adhesive which bonds the layer 30 to the rim 97, With the closure fully applied the liner, in particular the foamed layer 30, is compressed and forms a seal around the container neck 90. The heating process also weakens/removes the adhesion between the PET layer 20 and the top plate 60 by at least partly melting the adhesive layer 15. Figure 5 shows the closure and container neck following first removal of the closure. Because the adhesive layer 15 is weakened/removed, when the closure 50 is unscrewed the seal 10 remains on the container neck 90.

When access to the contents 92 of the container 90 is required the seal must be pierced. In this embodiment the seal is pierced by a separate tool 95 as shown in Figure 6. It will be seen that as the central region of the seal is torn by the tool it will be pushed into the mouth of the container. Because the foam layer 30 is restricted to the periphery of the seal, this layer will not be pushed into the container mouth and will not potentially come into contact with the product. Therefore only the PET layer 20 will potentially contact the product 85. Referring now to Figures 7 and 8 there is shown a seal 1 10 formed according to an alternative embodiment. The seal comprises a layer of PET 120, a layer of aluminium foil 125 and a layer of foamed polyethylene 127. The layer of PET 120 is formed as a complete disc, whereas the aluminium and foam layers 125, 127 are formed as rings which extend around the peripheral region of the PET layer.

The PET layer is present as a barrier layer, to prevent ingress of gasses which are deleterious to the container product.

The foam layer is present to form a physical seal around the container rim when a closure is applied.

The aluminium layer is required to attach the seal to a container rim.

The seal is formed as a heat induction sealed liner therefore in the first instance is fitted into a closure, which in this embodiment is a self-piercing closure (not shown). In use the closure is fitted onto a container neck so that the PET layer 120 abuts and fits around the top of the container neck rim 195 as shown in Figure 9. Thereafter the seal is secured to the container rim by a heat induction process. The induction process requires the aluminium layer to facilitate bonding of the PET layer to the container rim.

Subsequently, when the self-piercing closure is activated the seal will be pierced. However, because the aluminium and foam layers 125, 127 are restricted to the periphery of the seal, only the PET layer is in fact pierced and pushed down into the mouth of the container as shown in Figure 10. Therefore, only the PET layer 120 will come into contact with product in the container.

Referring now to Figures 1 1 to 13 there is shown a closure generally indicated 210. The closure 210 comprises a generally cylindrical base 220.

The closure 210 is intended to be fitted to a container neck (not shown) which at its open end is sealed by a laminar disc-shape liner 260 which in this embodiment will be induction heat sealed into position.

The base 220 comprises a cylindrical sidewall 221 which includes internal screwthread formations 222 for engaging corresponding external screwthread formations on the container neck. At the closed end of the sidewall, a platform 229 extends radially inwardly. From the inner edge of the platform 222 an upstanding collar 223 is provided. At the opposite end of the collar 223 to the platform 222 a sealing portion 224 extends radially inwardly and defines at its centre an aperture 225. Approximately half way along the portion 224 an annular sealing leg 226 depends and terminates with a sealing bead 227. The arm 224 terminates with a wedge-shape portion 228 which includes a downwardly depending section.

A self-closing valve 270 is provided. The valve 270 is of standard construction and briefly comprises a generally triangular section support ring 271 , a J-shape connecting wall 272 and a generally disc-shape concave valve head 273.

The valve 270 is fitted into the base 220 so that the segment 271 abuts against the portion 228 and the opposingly inclined surfaces allow for a stable interaction. A piercing member 280 is provided. The member 280 is generally annular and comprises a retention band 281 from which depends a cutting region comprising a plurality of teeth 282. At the end of the collar 281 opposite the teeth 282 a bead 284 projects radially inwardly. Extending parallel to the collar 281 on the opposite side of the teeth 282 is a retention jaw 285. In use, with the self-closing valve assembled into the base, the member 280 is snap fitted on to the base so that the bead 284 clips over the bead 227. At the same time, the jaw 285 engages the segment 271 so that it is held firmly between the portion 228 and the jaw 285. For this purpose the jaw 285 includes an inclined surface oppositely inclined to that side of the segment 271.

A liner 260 is provided and fits into the closure under the platform 229. The liner includes: an annular layer of foamed polyethylene 207 which seals against the platform; an annular layer of aluminium foil 205 attached to the layer 207; and a disc-shape layer of PET 202 attached to the layer 205.

In use the closure is applied to a container neck so that the liner 260 contacts the neck rim. The liner can then be induction sealed onto the neck rim.

The neck 223 is formed as a flexible membrane so that it can be pushed down from the position shown in Figure 1 to the position shown in Figure 15. In doing so, the piercing member 280 is pushed down to contact the panel 260. This pierces only the PET layer 202 of the panel because the layers 207, 205 are confirmed to the peripheral region not contacted by the piercing member. Subsequently product can flow from the container under the control of the self-closing valve 270.