FIELD OF THE INVENTION

The invention relates to packages which, after initial sealing closed, may be opened and subsequently resealed.

BACKGROUND

There are many applications for which it is desirable to be able to reseal a package closed after it has been initially opened.

Such packages may include packages formed of plastics film material which is heat sealable and which are heat sealed closed. Plastic bags may be formed from tubular film stock by heat sealing and cutting across the film stock to form each bag, with the mouth of the bag subsequently being heat sealed closed once the contents or product to be packaged is in the bag. Plastic packages which are heat sealed closed also include packages produced on a form, fill & seal machine as a sheet of plastics film material is wrapped around a product, and heat sealed longitudinally and at either end to close the package.

SUMMARY OF INVENTION

In broad terms in one aspect the invention comprises a package formed of a plastics film material having a heat sealable surface, the package being formed to have an interior, exterior, and so that said heat sealable surface generally faces the interior of the package, with a portion of the plastics film material folded back on itself to provide an exposed portion of said heat sealable surface on the exterior of the package, the package also comprising a closure flap which is heat sealed or heat sealable to said exposed portion of the heat sealable surface, and an adhesive area also on the exterior of the package to which said closure flap may be adhered to reseal the closure flap after heat sealing of said closure flap to said exposed portion of the heat sealable surface and subsequent breaking of the heat seal of the closure flap. In a further aspect the invention comprises a package formed of a plastics film material having a heat sealable surface on one side only of the plastics film material, the package being formed to have an interior, exterior, and so that said heat sealable surface generally faces the interior of the package, with a portion of the plastics film material folded back on itself to provide an exposed portion of said heat sealable surface on the exterior of the package, the package also comprising a closure flap which is heat sealed or heat sealable to said exposed portion of the heat sealable surface, and an adhesive area on the exterior of the package which fixes a terminal edge of said exposed portion of the plastics film material folded back, to the exterior of the package, and to which adhesive area said closure flap may be adhered to reseal the closure flap after heat sealing of said closure flap to said exposed portion of the heat sealable surface and subsequent breaking of the heat seal of the closure flap.

In a further aspect the invention comprises a package formed of a plastics film material having a heat sealable surface on one side only of the plastics film material, the package being formed to have an interior, exterior, and so that said heat sealable surface generally faces the interior of the package, with a portion of the plastics film material folded back on itself to provide an exposed portion of said heat sealable surface on the exterior of the package, the package also comprising a closure flap which is heat sealed or heat sealable to said exposed portion of the heat sealable surface, and an adhesive area on the exterior of the package with a terminal edge of said exposed portion of the plastics film material folded back adhered to cover a first part of said adhesive area leaving a second part of said adhesive area exposed, to which said second part the closure flap may be adhered to reseal the closure flap after heat sealing of said closure flap to said exposed portion of the heat sealable surface and subsequent breaking of the heat seal of the closure flap.

Preferably said adhesive area is a resealable adhesive area enabling separation of the closure flap from the adhesive area and subsequent resealing of the closure flap to the adhesive area. The invention enables a resealable package to be formed from a plastics film material which requires to be heat sealable on one side only of the plastics film material. It is common for plastics film materials used for packaging to be multi-layer materials, with each layer contributing different properties to the material. Resealable packages of the invention may be formed of a plastics film material having a peelable heat seal layer on one side only.

The term 'comprising' as used in this specification and claims means 'consisting at least in part of , that is to say when interpreting independent claims including that term, the features prefaced by that term in each claim will need to be present but other features can also be present.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is further described with reference to the accompanying drawings, by way of example, in which: Figure 1 is a perspective view of an embodiment of a package of the invention before breaking of the heat seal of the closure flap to open the package, Figure 2 is a perspective view of the package of Figure 1 after breaking of the heat seal of the closure flap and fully pulling back the closure flap to enable access to the interior of the package, Figure 3 is a view of the package of Figures 1 and 2 similar to Figure 2, after part removal of a release sheet over a strip of resealable adhesive across the exterior of the package, Figure 4 is a perspective view of the package of Figures 1 to 3 showing resealing of the closure flap to the strip of resealable adhesive to re-close the package, Figure 5 is a cross-section view along line I — I of Figure 1 of the top of the package of Figures 1 to 4, before breaking of the heat seal to initially open the package, Figure 6 is a cross-section view similar to Figure 5 of the top of an alternative embodiment of the package, and Figure 7 is a cross-section view similar to Figures 5 and 6 but of a further alternative embodiment of the package. DETAILED DESCRIPTION OF PREFERRED FORMS

Referring to Figures 1 to 5 which show a first embodiment of a package of the invention, the package is formed of a plastics film material having a heat sealable surface on at least one side of the film material. Optionally both sides of the film may be heat sealable, but the objective of the invention is to enable a resealable package to be formed from a film having a heat sealable surface on one side of the plastics film material only. Typically the heat sealable surface is provided by a laminated or co-extruded heat sealable layer on one side of the film.

In the embodiment shown the film is folded back on itself at 1 and heat seals 2 and 3 between the layers of film on either side close the sides of the package to define the interior of the package. The heat sealable surface of the film generally faces the interior of the package.

A portion 4 of the film is folded back at 3 (see Figure 5) on one side of the package, to provide an exposed portion of the heat sealable surface on an exterior side of the package. In this embodiment a strip of double sided adhesive comprised by a double sided adhesive tape 7 for example, across the exterior of the package, fixes a terminal edge 8 of the folded portion 4 to the side 6 of the package as shown. The opposite side of the adhesive strip 7 is preferably covered by a release sheet 9 in strip form (see Figures 2 and 3 but not shown in Figure 5). A closure flap 10 extends from the other side of the package as shown.

To initially form the closure, the flap 10 is heat sealed to the exposed heat sealable surface of the folded back portion 4 to form a peelable or frangible heat seal 11. To subsequently open the closure the closure flap 10 is pulled away from the side 6 of the package to break the peelable or frangible heat seal 11 along it's length. Figure 2 shows the package after breaking of the heat seal 11 and fully pulling back the closure flap 10. The pulled apart sides of the broken heat seal are indicated at l la and l ib in Figure 2. To subsequently reseal the package the closure flap 10 is then pressed against the exposed surface of the adhesive strip 7, after removal of a release sheet 9 over the adhesive strip 7 if provided (see Figure 3). The adhesive strip 7 may be a resealable adhesive so that the closure flap 10 may be pulled back to open the package and then resealed to the adhesive strip 7 a second and subsequent time. Less preferably, the adhesive strip 7 may allow only one sealing of the closure flap 10 to the adhesive strip 7, necessitating the second opening of the package being by tearing or cutting opening the package or the closure flap 10 and/or adhesive strip 7.

When the flap 10 is pulled back to initially open the package by breaking the heat seal 11, the film plies on either side of the heat seal 11 are pulled apart at about 180° at the heat seal. However, the opening force applied by pulling the flap 10 which is transmitted to the adhesive strip 7 stresses this in shear, with the structure being such that the heat seal 11 will fail, to enable opening of the package, before failure of the bond between folded back portion 4 and side 6 of the package.

Figure 6 is a view similar to Figure 5 of an embodiment similar to that of Figures 1 to 5 with the same reference numerals indicating the same elements as in Figure 5, except that in Figure 6 one side of a double sided adhesive strip 7 is applied to exterior side 6 of the package and the terminal edge 8 of the folded back portion 4 is adhered to the opposite side of adhesive strip 7 along a first part 7a of the adhesive strip, to fix the folded portion 4 to the side of the package. A release sheet (not shown) may be provided along a second part 7b of the adhesive strip 7, not covered by the terminal edge 8. To reseal the package after initial opening, i.e. after the flap 10 has been pulled away breaking the heat seal 11, the release sheet may be removed, enabling the closure flap 10 to be stuck down to the part 7b of the adhesive strip 7.

Figure 7 shows a further embodiment in which again the folded portion 4 is fixed to the exterior of the side 6 by a double sided adhesive strip 7. In this embodiment all of the adhesive strip 7 is covered by the terminal edge 8 of the folded portion 4. Alternatively a line of hot melt adhesive may be used instead of the adhesive strip 7. In this embodiment a second adhesive strip 12 is provided on the underside of the closure flap 10 as shown, typically also having a release cover sheet or strip (not shown). Again after the heat seal 11 has been broken to initially open the pack, adhesive strip 12 may be used to reseal down the closure flap 10 to the side 6 of the package.

It may not be necessary to provide a release sheet over the adhesive strips 7, or adhesive strip 12 in Figure 7. When the heat seal 11 is initially formed the closure flap 10 may also adhere to the adhesive strip 7 (or the exposed part 7b thereof- Figure 6) not covered by a release sheet. When the bag is initially opened by breaking the heat seal 11, the flap 10 will readily peel from the adhesive strip. Subsequently the bag may be reclosed by re-affixing the flap 10 to the adhesive strip.

The adhesive strip 7, and adhesive strip 12 in Figure 7, may comprise a continuous strip of adhesive, comprised by a double sided adhesive tape for example, or an adhesive strip may be extruded onto the exterior of the package. Alternatively the adhesive strip 7 may be provided as a series of separate adhesive zones or dots, and alternatively again simply a single adhesive zone or patch may be provided centrally of the package for resealing down the closure flap 10.

The closure structure described may be provided along a bag mouth where the package is a bag (including a pouch) as described. The closure need not necessarily be provided at an end of a package but could alternatively be provided to extend longitudinally or transversely across the centre region of the package for example. In the embodiments described the closure is shown provided at the mouth of a package heat sealed at either side and transversely to form the package (a package of the type typically formed on a form, fill and seal machine by wrapping a sheet of plastics film material around a product and heat sealing longitudinally and at either end to close the package). As indicated previously the package may be of any other form such as a package formed from tubular film stock. The package may also be a gusseted package and/or a package with a block bottom.

A closure structure of the invention may need not necessarily be provided only across a mouth of the package but could be provided across a mouth and down either side of a flap i.e the breakable heat seal 11 be formed across a flap 11 as described and also down either side of the flap, and a resealable adhesive area provided across the mouth closed by the flap and again optionally down either side.

Where the package is filled with product before being initially closed, filling of the package with product and closing of the package may not necessarily occur by the closure structure described (closure flap 10 or equivalent) but instead the closure of the invention may be formed in package and the package filled with product or product inserted into the package through another end or side of the package which is the heat sealed closed, the package then being resealably openable at the end of the package at which the resealable closure of the invention is provided. An advantage of the invention is that it enables a resealable package to be formed from a material having a heat sealable surface on one side only. It is not necessary that both the inner and outer surfaces of the plasties film material must be heat sealable. The plasties film material may simply be a two layer material, comprising a layer which provides the structural and/or barrier properties of the material, such as a bi-axially or oriented Nylon layer for example, and a heat sealable layer on one side only of the material. The material can therefore be a lower cost material.At the same time the closure enables the package to be heat sealed closed and also subsequently resealed after initial opening.

The foregoing describes the invention. Alterations and modifications as will be obvious to those skilled in the art are intended to be incorporated within the scope hereof as defined in the accompanying claims.