GB2041893A

GB2041893A - Improvements in or Relating to Overcaps for Containers Having Diaphragm Closures

Info

Publication number: GB2041893A
Application number: GB7904974A
Authority: GB
Original assignee: TI Fords Ltd
Current assignee: TI Fords Ltd
Priority date: 1979-02-13
Filing date: 1979-02-13
Publication date: 1980-09-17

Abstract

An overcap 1 for a container 6 having its mouth hermetically sealed by a metal foil diaphragm 7 not provided with a tear tab, comprises a projection 8 for piercing and cutting the diaphragm projecting radially from the cap top, and a guide member 9 projecting radially from the cap skirt and spaced from the projection 8 by a distance substantially equal to the radial thickness of the rim bead about the container mouth. The overcap may be a snap-on plastics cap. In other constructions, the projection 8 extends axially when the overcap is in its normal closing position either downwardly, Figures 5-7 (not shown), or upwardly, Figures 8 and 9 (not shown). In the latter construction, the overcap is inverted to pierce and cut the diaphragm. <IMAGE>

Description

SPECIFICATION Improvements In or Relating to Containers having Diaphragm Closures The present invention relates to containers having diaphragm closures and, more particularly, to containers of the type in which the mouth of the container is sealed by a foil diaphragm and a supplementary closure cap or overcap, such as a snap-on plastics cap, is also provided for protecting the diaphragm and enabling the container to be reclosed or resealed when the foil diaphragm has been removed.

United States patent specification Nos.

3892351,3973719 and 3988185 describe various aspects of a container and closure system of the above type which consists of a composite cylindrical container body having an outwardly rolled bead forming a rim about the mouth of the container, a coated or laminated metal foil diaphragm heat sealed to the top surface of the rolled bead, and having an integral tear tab folded-back over the top of the diaphragm, and a snap-on plastics overcap to protect the diaphragm. The composite container is formed from a spirally wound laminate comprising paper board, metal foil, and plastics laminations. The container is opened by first removing the protective overcap and then pulling the tear tab so as to peel-off the diaphragm from the container mouth.

In practice, the closure system as described in the aforementioned United States specifications is difficult to produce and has a number of disadvantages associated with the tear tab and the heat sealing of the diaphragm to the container. Hence, frequently, the sealed container is required to be air tight and the seal between the diaphragm and the container must be strong enough to withstand any excess internal pressure caused by atmospheric pressure changes, such as those occuring naturally or as a result of transportation over high mountain ranges or in unpressurised aircraft or aircraft compartments.

With a suitable choice of coating on the diaphragm and container there is little difficulty in producing a strong heat seal but, when this is produced, the consumer may not be strong enough to pee!-off the diaphragm in the intended manner or the tab may be torn-off leaving the diaphragm still in position. Furthermore, the presence of a folded tab on the diaphragm increases its cost compared with a simple circular diaphragm and can cause problems with the sealing process owing to the double thickness of material resulting in the tab region of the seal. It may also be necessary, as disclosed in United States specification No.3892351, to orientate the tab with respect of the unavoidable bump on the rim of the container bead so that these do not coincide.

It is an object of the present invention to avoid the problems which have hitherto been experienced with closure systems of containers of the type described and which result in unreliable seals and difficult opening characteristics, and to provide a closure system for such containers which can be used reliably to seal containers made from any material, such as, composite paper board/foil/plastics laminate, tin plate or other metal, or glass.

From one aspect, the invention consists in a container of the type described, in which the foil diaphragm is without a tear tab, and the closure cap includes a projection for piercing and cutting the diaphragm disposed on the outside of the cap, and guide means also disposed on the outside of the cap and spaced from the projection by a distance substantially equal to the radial thickness of the rim of the container mouth, said guide means being engagable with the external periphery of the rim and, when so engaged, locating the projection adjacent the inner periphery of the rim so that the projection can pierce the diaphragm and cut the latter along a substantially circular path inside the diaphragm zone sealed to the container rim when the cap and container are moved relatively to one another.

The foil diaphragm may comprise thin metal foil coated on its surface adjacent the container with a thermoplastic film, lacquer, adhesive or combination thereof which bonds to the container material under the action of heat and pressure. If desirable, the diaphragm may be provided with a shallow peripheral skirt to locate the diaphragm over the mouth of the container.

From another aspect, the invention consists in a plastics cap for a container of the type described, including a projection for piercing and cutting the foil diaphragm, which seals the container mouth, disposed on the outside of the cap, and guide means also disposed on the outside of the cap and spaced from the projection by a distance substantially equal to the radial thickness of the rim of the container mouth, said guide means being engagable with the external periphery of the container rim and, when so engaged, locating the projection adjacent the inner periphery of the rim for piercing the diaphragm and cutting the latter along a substantially circular path inside the diaphragm zone sealed to the container rim when the cap and container are moved relatively to one another.

In one embodiment, the cutting projection and guide means project substantially radially from the circumference of the cap. In another embodiment, the projection is formed at the circumference of the cap and projects downwardly on the outside of the cap skirt, and the guide means comprises the skirt which may, if necessary, be locally extended downwardly from the bottom edge of the cap skirt. In yet an other embodiment, the projection is disposed on the top of the cap adjacent, but spaced inwardly from, the circumference thereof, and the guide means comprises an upwardly projecting annular flange disposed about the circumference of the cap top, flush with the cap skirt.

The projection for piercing and cutting the diaphragm may be so shaped that the cut edge of the ring of diaphragm material, which remains on the container rim, is swaged downwardly to conform to the inner periphery rim, is swaged downwardly to conform to the inner periphery of the rim about the container mouth during the cutting operation. Alternatively, or in addition, the zone of the cap between the cutting projection and the guide means may be shaped to correspond to the adjacent profile of the container rim so as to assist or produce this swaging operation. In this way, the cut edge is smoothed downwardly to conform to the rim thus improving the appearance and reducing the risk of a consumer cutting his fingers on a sharp edge of foil.

In order that the present invention may be more readily understood, reference will now be made to the accompanying drawings, in which: Fig. 1 is a perspective view of a first embodiment of overcap for a container and closure system according to the invention, Fig. 2 is a plan view of the cap shown in Fig. 1, Fig. 3 is a fragmentary radial section along the line A-A of Fig. 2 showing the cap piercing the closure diaphragm sealing a container, Fig. 4 is a perspective view illustrating the manner in which the cap is used to cut the diaphragm.

Figs. 5, 6 and 7 are respectively a perspective view, a fragmentary elevation and a fragmentary radial section of a second embodiment of overcap, and Figs. 8 and 9 are respectively a perspective view and fragmentary radial section of a third embodiment of overcap.

In the different embodiments illustrated, like reference numerals indicated similar parts.

Referring to Figs. 1, 2 and 3 of the drawings, the overcap 1 is moulded from resilient plastics material, such as, polyethylene, and comprises a top 2 and a skirt 3. On its inside, adjacent its bottom edge, the skirt 3 is moulded with an inwardly directed bead 4 dimensioned to locate under a bead 5 formed about the rim of the mouth of a container 6 so as to enable the cap to be snapped onto the mouth of the container and retain it in position over the mouth.

The mouth of the container is hermetically sealed by means of a thin metal foil diaphragm 7 which is in the form of a plain circular disc without a tear tab, and is coated on its surface adjacent the container with a thermoplastics film, lacquer or adhesive which is bonded to the container material under the action of heat and pressure. This diaphragm is bonded to the upper surface of the rim bead 5.

Moulded integrally with the circumference of the cap top 2, in the plane of the top and projecting radially outwardly, is a iercing and cutting projection 8 which is of V-shape in plan.

The edges of this V-shaped projection and its point have a very small radius to eliminate any risk of a consumer accidentally cutting his hands and yet the point of the projection is sharp enough to pierce the thin foil of the diaphragm 7 sealing the container. Moreover, the edges of the projection are sharp enough to cut the foil as the cap is moved relatively around the container rim, as will hereinafter be described.

A radial guide member or abutment 9 is moulded integrally with the outside of the skirt immediately below the cutting projection 8 and symmetrically with respect to the latter. It projects radially outwardly from the bottom edge of the skirt by a distance greater than the projection 8 and is spaced from the projection by a distance substantially equal to the thickness of the rim bead 5 about the container mouth. This guide member assists in the operation of piercing and cutting the diaphragm closure along the desired circular path.

The zone 10 of the cap skirt between the projection 8 and the guide member 9 and the adjacent portions of the projection and guide member are shaped to correspond to the profile of the upper portion of the rim bead 5 so as to produce a swaging operation on the ring of diaphragm material remaining bonded to the bead as the diaphragm 7 is cut.

When it is desired to open the container 6 having the diaphragm closure 7 protected by the overcap 1, the overcap is removed and held in a plane at right angles to the container mouth (see Fig. 4) with the guide member 9 engaged against the external periphery of the bead 5 and with the cutting projection 8 innermost. This locates the projection adjacent the inner periphery of the bead, inside the annular zone of the diaphragm sealed to the bead, and the cutting projection is in a position to pierce the diaphragm when the cap is pressed downwardly onto the rim. Thereafter, manual rotation of the container relatively to the cap causes the projection to cut the diaphragm along a circular path 11 just inside the sealed zone.The profile of the zone 10 of the overcap causes the cutting operation to be accompanied by a swaging operation on the ring of diaphragm material left sealed to the bead 5 so that the cut edge is smoothed down to conform to the container rim, thereby improving the appearance and reducing the risk of a consumer cutting his fingers on remaining sharp edges of foil.

In the embodiment illustrated in Figs. 5, 6 and 7, the piercing and cutting projection 1 3 extends downwardly generally parallel to the cap skirt 3.

The projection is moulded integrally with the cap and is joined to the circumference of the cap top 2 by an extension 1 4. This extension spaces the projection from the cap skirt by a distance substantially equal to the radial thickness of the rim bead 5 about the container mouth. The projection is V-shaped in elevation and is similar in configuration to the projection 8 described in the previous embodiment. The underneath 1 6 of the extension 14, between the projection and the cap skirt, and the adjacent portions of the projection and skirt are so shaped as to correspond to the profile of the upper portion of the rim bead 5 so as to produce the swaging operation described above.Whilst the skirt 3, itself, may serve as the guide means for locating the projection for the pressing and cutting operation to remove the diaphragm closure 7, in this embodiment, the skirt is formed with a smail axial bulge 1 5 opposite the cutting projection and symmetrical therewith, which bulge serves as an additional guide portion for facilitating the piercing and cutting operation. When the cap is used to open the diaphragm closure 7, it is held in generally the same plane as the container mouth, and alongside it, with the guide portion 1 5 and adjacent portion of the skirt abutting the external periphery of the rim bead 5 and the projection 13 located adjacent the inner periphery of the bead.

If the consumer then exerts thumb pressure on the top of the cap at and adjacent the extension 14, the projection pierces the diaphragm in the desired position and rotation of the container relative to the cap produces the cutting and swaging operation, as in the previous embodiment.

In the third embodiment illustrated in Figs. 8 and 9, the piercing and cutting projection 17, which is of similar configuration to the projections shown in the two previous embodiments, is moulded integrally with the cap top 2, at a position spaced inwardly from the circumference thereof and the guide means comprises an upwardly projecting annular flange 18 formed as an upward extension of the cap skirt 3. The external cylindrical surface of the flange 1 8 is flush with the external surface of the skirt and the internal diameter of the flange is slightly greater than the external diameter of the bead 5 about the mouth of the container. The projection 1 7 is spaced from the guide flange by a distance substantially equal to the radial thickness of the bead and such that the bead can pass between them during the cutting operation.The zone 1 9 of the cap top between the projection and the flange and the adjacent portions of the projection and flange are shaped to correspond to the profile of the upper portion of the rim bead 5 so as to produce the required swaging operation. When it is desired to open a container, which is closed by a diaphragm closure and the overcap, shown in Figs. 8 and 9, the overcap is simply removed, inverted and replaced on the container, whereupon it is pressed down and turned so that the projection 1 7 pierces and cuts the diaphragm closure.

In case the method of removing the diaphragm closure 7 is not obvious to a consumer, instructions, either written or in the form of an illustration, such as Fig. 2, may be printed on the metal foil diaphragm material or moulded into the top of any of the overcaps described above.

Whilst particular embodiments have been described, it will be understood that modifications can be made without departing from the scope of the invention. Hence, instead of the overcap being a snap-on cap, it can equally well be formed with a screw thread or with lugs to engage a cooperating screw thread formed about the mouth of the container.

Claims

1. A container having its mouth sealed by a foil diaphragm and a supplementary closure cap engageable over the mouth of the container, in which the cap includes a projection for piercing and cutting the diaphragm disposed on the outside of the cap, and guide means also disposed on the outside of the cap and spaced from the projection by a distance substantially equal to the radial thickness of the rim of the container mouth, said guide means being engageable with the external periphery of the rim and, when so engaged, locating the projection adjacent the inner periphery of the rim so that the projection can pierce the diaphragm and cut the latter along a substantially circular path inside the diaphragm zone sealed to the container rim when the cap and container are moved relatively to one another.

2. A container as claimed in claim 1, in which the diaphragm is athin metal foil diaphragm coated on its surface adjacent the container with a thermoplastic film, lacquer, adhesive or combination thereof which bonds to the container material under the action of heat and pressure.

3. A container as claimed in claim 1 or 2, in which the diaphragm includes a shallow peripheral skirt to locate the diaphragm over the mouth of the container.

4. A supplementary closure cap for a container having its mouth sealed by a foil diaphragm, including a projection for piercing and cutting the foil diaphragm disposed on the outside of the cap, and guide means also disposed on the outside of the cap and spaced from the projection by a distance substantially equal to the radial thickness of the rim of the container mouth, said guide means being engageable with the external periphery of the container rim and, when so engaged, locating the projection adjacent the inner periphery of the firm for piercing the diaphragm and cutting the latter along a substantially circular path inside the diaphragm zone sealed to the container rim when the cap and container are moved relatively to one another.

5. A container or cap as claimed in any one of the preceding claims, in which the cutting projection and guide means project substantially radially from the circumference of the cap.

6. A container or cap as claimed in any one of the preceding claims 1 to 5, in which the projection is formed at the circumference of the cap and projects downwardly on the outside of the cap skirt, and the guide means comprises the skirt.

7. A container or cap as claimed in claim 6, in which the skirt is locally extended downwardly from the bottom edge of the cap skirt adjacent the projection.

8. A container or cap as claimed in any one of the preceding claims 1 to 5, in which the projection is disposed on the top of the cap adjacent, but spaced inwardly from the circumference thereof, and the guide means comprises an upwardly projecting annular flange disposed about the circumference of the captor.

9. A container or cap as claimed inany one of the preceding claims, in which the projection is shaped so that the cut edge of the ring of diaphragm material which remains on the container rim, is swaged downwardly to conform to the inner periphery of the rim during the cutting operation.

10. A container or cap as claimed in any one of the preceding claims, in which the zone of the cap between the cutting projection and the guide means is shaped to correspond to the profile of the container rim, thereby to assist or produce downward swaging of the ring of diaphragm material, which remains on the container rim, to conform it to the inner periphery of the rim about the container mouth during the cutting operation.

11. A container or cap as claimed in any one of the preceding claims, in which the projection is Vshaped in plan and the edges and point of the projection are radiused to avoid accidental cutting of a person and yet are shart enough to pierce the foil diaphragm and cut the foil.

12. A container or cap as claimed in any one of the preceding claims, in which the cap is moulded from plastics material and is formed as a snap-on cap.

13. A container constructed substantially as hereinbefore described with reference to Figures 1 to4,or5,and6and7,or8and90fthe accompanying drawings.

14. A supplementary closure cap for a container, constructed substantially as hereinbefore described with reference to Figures 1 to 4, or 5,6 and 7, or8and9ofthe accompanying drawings.