Patent Description:
It is common for food stuffs to be packaged within metal cans having metal lids that are press-fitted into the openings in the can bodies. The lids can be pried-off of the can bodies using, for example, the end of a spoon. Such cans are often used with dried food products such as cocoa powder or relatively viscous products such as treacle and syrup. As the seal between the can body and the lid is formed between opposed metal surfaces however, and is generally not airtight at least following opening and reclosing, such cans are generally not used for products that either degrade when in contact with the air or which otherwise require a higher standard of hygiene, such as is the case with infant formula.

For perishable products such as infant formula, assuming that a metal can body is used, a closure system is often used that has a peelable foil lid sealed to the upper surface of a bead pressed into the can body adjacent to the opening. Once the lid is peeled off it is of course not possible to tightly reclose the can with that foil lid. To facilitate reclosure a plastic overcap is typically provided and which is press-fitted over the can body opening above the foil lid. The plastic overcap also provides protection for the relatively weak foil lid during transit and storage. As it is desirable to allow customers to see the foil and verify its integrity prior to purchase, the plastic overcap is often fully or at least partially transparent.

Producers and consumers are keen to reduce the use of plastics and therefore plastics waste. There is therefore a desire to produce an all metal food can which provides a seal between the can body and the lid that is of sufficient integrity to provide for the long term storage of perishable food stuffs whilst allowing for reclosing.

<CIT> describes a can body of a single homogeneous piece of material comprising: an edge defining an upper opening into the body: an inwardly directed pinched or collapsed bead pressed into and extending around the can body adjacent to said edge, the pinched or collapsed bead defining a flange providing an upwardly facing sealing surface; and an inwardly directed bead extending around the body between the edge and the pinched or collapsed bead. The can body is configured such that a lid can be press or snap fitted into the upper opening and retained in sealing engagement between the two beads.

<CIT> describes a container made up of the combination of a body and a lid, incorporating a peripheral lip around the periphery of the lid thereof, said lip forming a downward-facing groove, also peripheral, holding a strip of rubber that constitutes the support means via which the lid presses over the mouth of the body of the container, said lid being closed simply by applying the vacuum to the inside of the container. The lid also has, at the centre thereof, a small hole covered by an adhesive tab with a non-adhesive extension for gripping said tab. To remove the lid from the body, there is no need to detach it completely, but rather all that is required is to pull on said tab so that the container opens instantly in an extremely quick and easy movement.

Embodiments of the present invention provide a metal food can that provides an air and liquid tight seal combined with a means for allowing consumers to verify the integrity of the seal prior to first opening, whilst avoiding the need for a plastics overcap.

According to a first aspect of the present invention there is provided a can comprising a metal can body having an edge defining a top opening into the body, the body further comprising an inwardly directed bead extending around the body adjacent to said top opening, the bead defining an upwardly facing sealing surface and an inwardly facing surface. The can further comprises a metal lid having a centre panel, a wall surrounding said centre panel, an outwardly directed curl at the top of said wall, the curl defining a peripherally extending channel having an opening therein, and sealing compound located within said channel and projecting through said opening. The can body and the lid are dimensioned to allow the lid to be press-fitted into the can body so that an outwardly facing surface of said wall opposes the inwardly facing sealing surface of said bead, whilst said sealing compound is in sealing engagement with said upwardly facing sealing surface of the bead.

The can body may be a single piece can body and said inwardly directed bead is pressed into the can body.

The can body may comprise an annular can end component fixed to a can body wall, said component defining the inwardly directed bead.

The can further comprises an end closing a bottom of said can body, the lid being engaged with the can body and the can body containing a product, a partial vacuum being present within the can in order to pull the lid onto the can body, thereby compressing said sealing compound between the lid and the can body and effecting a substantially air tight seal between the lid and the can body.

The centre panel defines a pop-up button within a central region thereof, such that the button is depressed when the lid is engaged with the can body and a partial vacuum is present within the can and is in a raised position when the partial vacuum is released.

The can body and the lid may be dimensioned to provide a gap of at least <NUM> between an outermost edge of said curl and an inner surface of said top opening.

A gap between the upwardly facing sealing surface of the bead and a top of the edge may be approximately <NUM>.

The can body may comprise a sheet of metal rolled into a cylinder with a welded seam joining the opposed edges of the sheet.

The can body may comprise a base secured to the can body to close a bottom opening of the can body.

The edge of the can body may be a curled edge.

The radially outermost region of the inwardly directed bead may be collapsed in an axial direction to substantially close the bead to an area surrounding the can body.

The inwardly directed bead may have a substantially oval axial cross-sectional shape.

The upwardly facing sealing surface and the inwardly facing surface defined by the bead may be substantially convex.

The outwardly facing surface of the lid wall may be substantially flat.

The can body and the lid may be dimensioned such that, when the lid is press-fitted into the opening of the can body, an upper surface of the lid is below the top of the can body.

When the lid is engaged with the can body, the outwardly facing surface of the wall may abut the inwardly facing sealing surface of the bead, providing a metal to metal seal.

When the lid is engaged with the can body, the sealing compound may extend over the outwardly facing surface of the wall to seal said outwardly facing surface to the inwardly facing sealing surface of the bead.

<FIG> illustrate a can <NUM> (for example, a food can or "tin") comprising a metal can body <NUM> and a metal lid <NUM>. The can body <NUM> has an upper curled edge <NUM>, or rim, defining a top opening into the body <NUM>, and comprises an inwardly directed bead <NUM> extending circumferentially around the body <NUM> adjacent to the top opening.

The top of the bead <NUM> is spaced approximately <NUM> from the top of the edge <NUM>. As is pointed out in <FIG>, the inwardly directed bead <NUM> defines a substantially upwardly facing sealing surface <NUM> and an inwardly facing sealing surface <NUM>. The metal lid <NUM> has a centre panel <NUM>, a wall <NUM> surrounding the centre panel <NUM> and an outwardly directed curl <NUM> at the top of the wall <NUM>. The curl <NUM> defines a circumferentially extending channel <NUM> having an opening <NUM> therein. Sealing compound such as plastisol <NUM> is located within the channel <NUM> and projects through the opening <NUM>.

The inwardly directed bead <NUM> may be pressed into the body <NUM>, such that the body <NUM>, including the bead <NUM>, is formed from a single, homogeneous piece of metal, as best illustrated in <FIG>. Alternatively, a separate annular can end component (i.e. a ring) may be attached to the can body to enable the lid to be replaceably secured to the top opening of the can body. For example, the ring may be non-removably seamed around the top opening of the can body. The ring may be made by stamping out a blank from a flat sheet and subsequently forming the blank to have an appropriate cross-sectional shape, defining an annular space or gap between the inner and outer edges of the ring. The ring may be further formed at its innermost region to provide a substantially circular, upwardly facing sealing surface and an inwardly facing sealing surface.

The can body <NUM> and the lid <NUM> are dimensioned to allow the lid <NUM> to be press-fitted into the can body <NUM>, so that an outwardly facing surface <NUM> of the lid wall <NUM> abuts the inwardly facing sealing surface <NUM> of the bead <NUM>, and the sealing compound <NUM> is in sealing engagement with the upwardly facing sealing surface <NUM> of the bead <NUM>.

As best illustrated in <FIG>, the can body <NUM> comprises a base <NUM> secured to the can body <NUM> to close a bottom opening of the can body <NUM>. The base <NUM> may, for example, be secured to the can body <NUM> by seaming. The can body <NUM> is generally cylindrical in shape, and is formed from a sheet of metal rolled into a cylinder. Opposed edges of the metal sheet are joined together via a welded seam (not shown here). The can body <NUM>, lid <NUM> and base <NUM> may be formed from steel, tinplate, aluminium, or other suitable metal or metal alloy. Preferably, a single material is used for all three elements of the can <NUM> such that the can <NUM> is more easily recyclable.

<FIG> illustrates the can lid <NUM> in more detail. The centre panel <NUM> of the lid <NUM> defines a circular, bi-stable pop-up button <NUM> within a central region thereof. As shown in Figures and 2c 2b, the button <NUM> may comprise an outer, inclined wall 33a circumferentially surrounding a substantially flat panel 33b, in the centre of which is an inner circular region 33c. The inner circular region 33c is configured to be moveable between a position in which it is slightly raised above the flat panel 33b (as shown in <FIG>), and a position in which it is substantially level with the flat panel 33b (<FIG>). The button <NUM> may have a height above the centre panel <NUM> of approximately <NUM> when in a raised position, as shown in <FIG>. In one non-limiting example, where the centre panel <NUM> has a diameter of approximately <NUM>, the button <NUM> may have a diameter of approximately <NUM>.

When the lid <NUM> is engaged (i.e. press-fitted) with the can body <NUM>, and a partial vacuum is present within the filled can <NUM>, the pop-up button <NUM> is depressed, as shown in <FIG>.

In this depressed position, an upper surface of the pop-up button <NUM> (i.e. the flat panel 33b and the inner circular region 33c) may be substantially level with the centre panel <NUM>. When the partial vacuum is released from the can body <NUM> during removal of the lid <NUM> or as a result of a leak caused by a failure in the can, the pop-up button <NUM> moves to a raised position (<FIG>). In the raised position, an upper surface of the pop-up button <NUM>, comprising at least the inner circular region 33c, is above a level of the centre panel <NUM> but is easily depressed by a user. The pop-up button <NUM> thereby provides a tactile and visual indication that the partial vacuum has been released (i.e. tamper evidence).

As illustrated in <FIG>, when a partial vacuum is present within the can <NUM>, the can lid <NUM> is pulled onto the can body <NUM>. This acts to compress the sealing compound <NUM> that is positioned between the lid <NUM> and the can body <NUM>, providing a substantially air tight seal between the lid <NUM> and the can body <NUM>. The sealing compound <NUM> is preferably foamed to improve compressibility and provide an effective vacuum seal between container body <NUM> and lid <NUM>.

In this example, once press-fitted onto the can body <NUM>, the top of the lid curl <NUM> is below the curled edge <NUM> (i.e. the rim) that defines the top opening of the can body <NUM>. This arrangement may assist in protecting the vacuum seal, e.g. preventing accidental knocking of the lid during transport.

<FIG> also illustrates the engagement of the lid <NUM> with the can body <NUM>. The sealing compound <NUM> is located partially within the channel <NUM> defined by the outwardly directed curl <NUM> in which the lid wall <NUM> terminates. The curl <NUM> is open to the extent that the channel <NUM> has an opening <NUM> substantially facing the bead <NUM> of the can body <NUM>. In this example, the compound <NUM> substantially fills the channel <NUM> and also projects through the channel opening <NUM>, such that it extends down a portion of the lid wall <NUM>. An outer surface of the lid wall <NUM> forms an outwardly facing sealing surface <NUM> which engages with the bead <NUM>. The sealing surface <NUM> formed by the lid wall <NUM> may be substantially flat. In this example, the lid sealing surface <NUM> directly contacts the bead <NUM> to provide a metal-to-metal configuration.

In an alternative arrangement, not shown here, the sealing compound may extend further down the lid wall <NUM> such that lid sealing surface <NUM> does not directly contact the bead; instead the compound <NUM> forms a seal between the lid sealing surface <NUM> and the bead <NUM>.

As shown in <FIG>, the bead <NUM> may be "crushed", i.e. the radially outermost region <NUM> of the bead <NUM> may be collapsed in an axial direction. This substantially closes the bead <NUM> to an area surrounding the can body <NUM>, thus preventing dirt and/or other objects from entering the bead's interior. Similarly, the upper end of the can body <NUM> may terminate in a closed curl <NUM> which forms the curled edge <NUM>, which prevents ingress of dirt and avoids sharp edges on the can <NUM>. In other embodiments however the bead <NUM> may be left open to a greater or lesser extent.

In this illustrated example, the bead <NUM> has a substantially oval axial cross-sectional shape. The bead <NUM> may be substantially symmetrical about a longitudinal axis A. The upwardly facing sealing surface <NUM>, defined by the bead <NUM> is substantially convex (i.e. outwardly curved). Similarly, in this example, the inwardly facing sealing surface <NUM> defined by the bead <NUM> is substantially convex in shape.

In use, the lid <NUM> is provided with a layer of sealing compound <NUM> within the channel <NUM> and is then press-fitted onto the can body <NUM>. The sealing compound <NUM> protrudes through the channel opening <NUM> such that the sealing compound <NUM> forms a seal against the upwardly facing sealing surface <NUM> of the can body bead <NUM>, and such that the lid sealing surface <NUM> engages with the inwardly facing surface <NUM> of the can body bead <NUM>. As previously discussed, the partial vacuum formed within the can body <NUM> holds the lid <NUM> onto the can body <NUM>, such that the sealing compound <NUM> is compressed against the bead <NUM>. This partial vacuum may be formed during filling, e.g. by steam flushing or vacuum seaming, or may result from a cooling of a hot filled product.

The seal between the layer of sealing compound <NUM> provided on an underside of the lid rim, and the bead <NUM> of the metal can body <NUM>, ensures that the partial vacuum within the can body <NUM> is securely maintained, even where the can is dropped or knocked. In the case of a can body <NUM> having a longitudinal weld, as described herein, a metal-to-metal seal alone may be insufficient to maintain the vacuum whereas sealing using a compound allows the discontinuity resulting from the weld to be effectively smoothed-out.

Referring back to <FIG>, the can body and the lid are dimensioned to provide a gap <NUM> of at least <NUM> between an outermost edge of the lid curl <NUM> and an inner surface <NUM> of the top opening of the can body. Preferably, this gap <NUM> may be between <NUM> to <NUM> wide. This gap is sufficient to allow the lid to be removed with a suitable lever. This is illustrated in <FIG> where, in order to remove the lid <NUM> and open the can <NUM>, the end of a spoon <NUM> is inserted into the gap <NUM>. It will be appreciated that the lid <NUM> may be subsequently pushed back on to re-close the can body <NUM>. In this case, a seal is re-formed between the compound and the bead (although clearly the vacuum seal cannot be re-formed). This is particularly useful for products which deteriorate on exposure to air.

Claim 1:
A can (<NUM>) comprising:
a metal can body (<NUM>) having an edge (<NUM>) defining a top opening into the body (<NUM>), the body (<NUM>) further comprising an inwardly directed bead (<NUM>) extending around the body (<NUM>) adjacent to said top opening, the bead (<NUM>) defining an upwardly facing sealing surface (<NUM>) and an inwardly facing surface (<NUM>);
a metal lid (<NUM>) having a centre panel (<NUM>), a wall (<NUM>) surrounding said centre panel (<NUM>), an outwardly directed curl (<NUM>) at the top of said wall (<NUM>), the curl (<NUM>) defining a peripherally extending channel (<NUM>) having an opening (<NUM>) therein, and sealing compound (<NUM>) located within said channel (<NUM>) and projecting through said opening (<NUM>); and
an end closing a bottom of said can body (<NUM>),
the can body (<NUM>) and the lid (<NUM>) being dimensioned to allow the lid (<NUM>) to be press-fitted into the can body (<NUM>) so that an outwardly facing surface (<NUM>) of said wall (<NUM>) opposes the inwardly facing sealing surface (<NUM>) of said bead (<NUM>), whilst said sealing compound (<NUM>) is in sealing engagement with said upwardly facing sealing surface (<NUM>) of the bead (<NUM>),
the lid (<NUM>) being engaged with the can body (<NUM>) and the can body (<NUM>) containing a product, a partial vacuum being present within the can in order to pull the lid (<NUM>) onto the can body (<NUM>), thereby compressing said sealing compound (<NUM>) between the lid (<NUM>) and the can body (<NUM>) and effecting a substantially air tight seal between the lid (<NUM>) and the can body (<NUM>);
wherein said centre panel (<NUM>) defines a pop-up button (<NUM>) within a central region thereof, such that the button (<NUM>) is depressed when the lid (<NUM>) is engaged with the can body (<NUM>) and a partial vacuum is present within the can (<NUM>) and is in a raised position when the partial vacuum is released.