GB2060541A - Packs incorporating opening means - Google Patents

Abstract

A pack comprises two elements (2,4), at least one of which is flexible, joined around the major part of their peripheries (16, 18) to define a product-containing region (6) between them, and pack-opening means (8) comprising two overlapping leaves (10, 12) joined together along one margin, (14) and interposed between the remaining parts of the peripheries of the two elements with said one margin located towards the inside of the pack, and said remaining parts of the peripheries of the two elements being joined to the outer surfaces of the leaves, thereby closing the pack but enabling opening thereof by manually lifting apart the leaves and pulling to separate the leaves from each other along said one margin. The leaves may be in strip form as illustrated or they may be triangular and inserted in a corner of a pack. <IMAGE>

Description

SPECIFICATION Packs made, for example, of plastics film This invention relates to packs made, for example, of plastics film and particularly packs of the general kind used for packing products such as cheese, meats, and items of hardware, these packs comprising two elements of for example plastics film which are joined, usually by heat sealing, around their peripheries to define a product-containing region between them.

Such packs are normally very troubiesome to open. Attempts have been made to make opening easier, such as the provision of tear notches, peelable heat seals, and tear tapes, but they all have significant disadvantages. One disadvantage common to all of them is that they do not make it visibly obvious to the user how the pack is intended to be opened; printed instructions are normally ignored so that many ineffective attempts may be made to open the pack until eventually one succeeds, though not necessarily in the way which was intended.

Tear notches are simply notches, normally triangular, cut into opposite edges of the pack, and normally into the heat-seal area, which provide a stress-concentration point facilitating tearing through the complete pack starting at that point.

However, in non-orientated polymer films frequently used in such packs, the tear can go in any direction which is not satisfactory. In an orientated polymer, the orientation can be arranged to make the tear travel in the right direction but films of orientated polymers are not strong enough for many applications.

To form a peelable seal between the two elements forming a pack, special sealing tachniques have to be employed requiring very close temperature control and since this is not always in practice achieved the seals formed are not consistent. Also, to provide a convenient starting point from which peeling apart of the two elements can be started, it is usual to provide substantial excess material beyond the sealed area on one side of the pack and this of course uses additional material, with the attendant added cost, and produces a less compact type of pack.

Tear tapes of strong plastics material are incorporated in some packs, by being heat sealed between the two elements which form the pack, the tape passing out through, and being sealed into, the main seal of the pack on opposite sides thereof. However, provision of tear tapes is complicated in production by the necessity to have a portion of the tape protruding so that a user has something to get hold of to initiate opening the pack. There are also problems in achieving a hermetic seal at the edges of the tear tape where it passes through the pack heat seals, resulting in a degree of spoilage of food materials in such packs.

An object of the present invention is to provide a pack which overcomes to a substantial extent one or more of these disadvantages.

In accordance with the invention there is provided a pack comprising two elements, at least one of which is flexible, joined around part of their peripheries to define a product-containing region between them, and pack-opening means comprising a component having two overlapping leaves joined together along one margin of the component, the component being interposed between remaining parts of the peripheries of the two elements with said one margin located towards the inside of the pack, and said remaining parts of the peripheries of the two elements being joined to the outer surfaces of the component leaves, thereby closing the pack at said remaining periphery parts but enabling opening thereof by manually lifting apart the leaves and pulling to separate the leaves from each other along said one margin.

As will become apparent, the leaves form an effective means of opening the pack and, importantly, a visibly obvious way in which the pack should be opened.

Preferably the two overlapping leaves are joined together by a peelable adhesive. Such adhesives are well known and need not be described in detail.

Preferably the peelable adhesive is continuous along said margin, thus enabling hermetic sealing of the complete pack, but discontinuities could be incorporated if such sealing is not important.

Preferably, the peelable adhesive extends across between one-third and two-thirds of the width of the component.

In a further embodiment of the invention the two overlapping leaves are formed from a single piece of material folded on itself, the fold forming the join between the leaves. In this case the leaves are separated by tearing, and the fold helps to form an initiation point and a directional guide for the tear, an orientated polymer film being preferred for this type of component, with its direction of easy tear lying along the fold.

At least one of the ends of the component may be cut in the region of the fold to provide a stress concentration point to assist in tearing apart the two leaves.

To restrict the extent to which the leaves may gape apart in the finished pack, which is unsightly and undesirable for other reasons, the mutually facing inside surfaces of the leaves may be joined together in localised spaced apart areas. This may be done by spots of adhesive, or by stripes of peelable adhesive as will be described in more detail.

Preferably the outer surfaces of the overlapping leaves are heat sealed to respective ones of the two elements.

A further feature which gives substantial advantages in mass preparation of the packs is for each leaf to have a laminated structure, the outer leaf surfaces being of material heat-sealable to the respective one of the two elements and the inner leaf surfaces being of materials, which may or may not be identical, but which are not heat sealable together at the heat sealable temperature of the outer leaf surface material. This enables formation of the leaf/element heat seals in one operation without heat sealing the leaves together Further, it is preferred that the two elements be joined around said part of their peripheries by heat sealing simultaneously with the heat sealing of the opening component between the elements.Thus, existing equipment employed to form a continuous peripheral heat seal round a pack can be employed in its usual manner to form a pack which nevertheless incorporates the easyopening features of the present invention.

In one embodiment of the invention, the two members are both of flat flexible plastics film.

In an alternative embodiment, said one member is of flat flexible plastics film and the other member if formed as a tray either from flexible plastics film or from semi-rigid plastics sheet, depending upon the product intended to be packed therein.

It should be understood that references to plastics film and plastics sheet include the incorporation of non-plastics materials such as layers of cellulose film, paper or metal foil.

In order that the invention may be more clearly understood, some embodiments thereof will now be described, by way of example, with reference to the accompanying drawings, in which: Figure 1 is an exploded perspective view of a pack in accordance with the present invention; Figure 2 is a longitudinal cross-section through the pack shown in Figure 1; Figure 3 is a similar cross-section through a flat pack in accordance with the invention Figure 4 is a perspective view of an alternative type of two-leaf opening strip which may be used in carrying out the invention; Figure 5 shows a modification of the opening strip of Figure 1; Figure 6 shows in plan the incorporation of a double width opening strip into linked packs; Figure 7 is a partial perspective view of a pack in accordance with the invention having a triangular opening component; and Figure 8 shows how four triangular opening components may be pre-formed for incorporation in linked packs.

Referring to Figures 1 and 2, the pack shown comprises a flexible plastics film element 2 and a further tray-shaped element 4 which may also be formed from flexible plastics film or from, for example, semi-rigid plastics sheet. These define between them a product-containing region 6 in which the product will be placed before the pack is assembled together Pack-opening means is provided in the form of a strip generally indicated at 8 having two overlapping leaves 10 and 12 which are joined together along the margin 14 of the strip by means of a suitable peelable adhesive. The area covered by adhesive is indicated by the lines of hatching in Figure 1 and extends preferably between one-third and two-thirds of the total width of the strip, and typically about half the width of the strip.

The elements 2 and 4 are of materials which can be heat-sealed together. Typically, elements 2 and 4 may be of laminated form, with the innermost lamination being of polyethylene, so that the contacting surfaces are both of polyethylene and are readily heat-sealable together.

Each of the leaves 10 and 12 is also a laminated plastics film, the materials being arranged so that the outer surfaces of the leaves i.e. the upper surface of leaf 12 and the lower surface of leaf 10 are of material readily heatsealable respectively to element 2 and element 4 and the inner surfaces of the leaves are not heatsealable to each other, at least not at the temperature employed for heat sealing elements 2 and 4.

In assembling the pack, the components will be presented in the relative positions shown in Figure 1, but all contacting each other and with a product in the tray 4, to a heat sealing device of the kind commonly employed, in which elements above and bellow the pack clamp together the peripheral regions of the pack materials and apply heat to them so as to heat seal all round the edge of the pack. Consequently the peripheral area 1 6 of element 2 is heat sealed to the peripheral area 1 8 of the tray element 4 all round the periphery except in the area of the strip 8.There, the margin of the upper surface of leaf 12, indicated in broken lines at 20 becomes heat sealed to the overlying marginal portion 1 6 of element 2, while the marginal portion of the lower surface of leaf 10, also indicated in broken lines, at 22, becomes heat sealed to the corresponding portion of the peripheral area 1 8 of the tray-like element 4.

However, the two inner and facing surfaces of leaves 10 and 12, being of materials which will not heat seal to each other at the temperatures employed remain separate.

During the above sealing process vacuum may be applied to the pack using standard techniques, so as to produce a hermetically-sealed vacuum pack. For hermetic sealing, the peelable adhesive must extend right up to the edge of the strip adjacent to marginal area 14, but this is not necessary in applications where non-hermetic sealing is adequate.

It can be seen from Figure 2 that the pack produced has an obvious opening point at the end where the leaves 10 and 12 are present. By manually lifting apart these leaves and pulling to separate them, the adhesive between them peels, and the leaves become completely separated, thus opening the pack adjacent to one end. If the peeling movement is continued the top of the pack can be completely opened, which may occur by the heat seal down the two edges of the pack peeling, or by the element 2 or even the element 4 breaking away adjacent to the peripheral heat seals.

To improve the appearance of the finished pack, localised areas of peelable adhesive may be provided between the inner surfaces of leaves 10 and 12, as indicated by the dots of peelable adhesive 24 shown in Figure 1. In practice, of course, if these were present the leaves would not be parted in the manner shown in Figure 1. The adhesive spots prevent the leaves from gaping apart thus improving the appearance of the pack but nevertheless let the edges of the leaves appear free so that the opening point of the pack remains obvious to the user.

Figure 3 shows a further embodiment of the invention, suitable for example for packing flat products such as sliced bacon or sausage, in which the lower element 4' is also a flat flexible plastics film like the upper element 2. It should be appreciated that once the leaves of the opening strip 8 have been pulled apart one leaf and the adjacent portion of element 2 or 4 (or 4') form between them a pocket into which the other leaf and its attached portion of element 4 (or 4') or 2 can be tucked thus providing the pack with a degree of recloseability provided it is not pulled completely open in the first instance.

In Figure 4 an alternative form of opening strip 8 is illustrated which is formed from a single piece of material which is folded double about a fold line 26 to form two leaves 12' and 10' joined together along the fold line. This may be employed instead of the type of strip 8 shown in Figure 1 and it may be laminated from similar materials, though they should be of orientated structure to facilitate tearing along the direction of the fold line 26.

Since this type of strip will not in practice tear across its whole width at once, tearing should be initiated at one end and to facilitate this the strip may be cut at one or, preferably, both ends in the vicinity of the fold to provide a stress concentration point. The cuts are shown as notches 28 in Figure 4 but could be simple slits or part-circular cut out portions.

Figure 5 also illustrates that in a strip of the kind shown in Figure 1 the localised peelable adhesive regions for temporarily holding the leaves together may be in the form of stripes 30 of peelable adhesive, which preferably are at an oblique angle to the strip as illustrated.

Figure 6 illustrates how an opening strip of double width can be introduced simultaneously between the main elements 2 and 4 of two packs on a packaging line. The Figure is a plan view showing the two packs 2, 4 in broken lines at a stage when they are still linked together, the upper elements 2 of both packs being integral parts of a single wide strip of plastics film and the lower elements 4 of both packs also being integral parts of a further such wide strip, as is common on packaging lines. After formation of the packs they are severed from each other along the chain dotted centre line 32 and are severed from further packs located above and below them (as viewed in Figure 6) along the horizontal broken lines 34.

In the course of pack formation the wide film strips for forming elements 2 and 4 are superposed with the double width opening strip located between them and centred on line 32. The double width opening strip itself is in a pre-formed continuous length twice as wide as each intended opening strip 8 and comprises an upper length of film superposed on a lower length of film, with peelable adhesive stripes, indicated by the hatching, holding them together along both their marginal areas 14 and peelable adhesive dots 24 to either side of line 32.

Once the packs are closed and sealed, while still linked, severance along lines 32 and 34 will result in each pack incorporating a separate opening strip of the kind shown in Figure 1.

Figure 6 also illustrates that the peelable adhesive holding the leaves 10 and 12 together may have a serrated pattern 36 along the edge nearest the free edges of the leaves so as to make initiation of the peeling easier.

Packs such as have been described are readily manufactured on conventional packaging machines with little or no modification except the addition of an unwinding station from which opening strip can be fed, preferably in double width form as shown in Figure 6, from a reel, in between the other pack components.

Figure 7 is an opened up perspective view of a corner of a pack of the generai kind shown in Figure 1 in which the opening component is equivalent to that shown in Figure 1 but is triangular and inserted into the corner of the pack.

The features are indicated by the same reference numerals as are used for their equivalents in Figure 1, but with double primes added. The manner of assembling and opening the pack may be as described with reference to Figure 1.

Figure 8 is a plan view of a square of two superposed plastics films with interposed peelable adhesive, forming four integral opening components of the kind shown in Figure 7 for simultaneous incorporation in adjacent corners of four linked packs. The square is separated into four opening components at the same time as the packs are separated, by severance along the -directions of diagonal lines 38.

A corner-fitting opening component may also be of the folded form illustrated in Figure 4.

The use of opening components as herein described offers an opportunity to provide information or decorative material on the component itself which in some applications may completely avoid the necessity for printing information or decorative material on the main pack elements.

In the packaging process which has been described the pack is not formed until the product has been inserted between its components.

However, the pack may be pre-formed, with the opening component sealed into it, but left open along one edge, such as the edge opposite the end where the opening component is located, for subsequent filling of the product through the opening followed by sealing of the opening.

An opening component such as has been described may be produced and sold as a separate product, for incorporation in packs by a user, and forms in itself an aspect of the present invention.

Claims (26)

1. A pack comprising two elements, at least one of which is flexible, joined around part of their peripheries to define a product-containing region between them, and pack-opening means comprising a component having two overlapping leaves joined together along one margin of the component, the component being interposed between remaining parts of the peripheries of the two elements with said one margin located towards the inside of the pack, and said remaining parts of the peripheries of the two elements being joined to the outer surfaces of the leaves, thereby closing the pack at said remaining periphery parts but enabling opening thereof by manually lifting apart the leaves and pulling to separate the leaves from each other along said one margin.

2. A pack as claimed in claim 1, wherein the two overlapping leaves are joined together by a peelable adhesive.

3. A pack as claimed in claim 2, wherein the peelable adhesive is continuous along said margin.

4. A pack as claimed in claim 2 or claim 3, wherein the peelable adhesive extends across between one third and two thirds of the width of the component, measured transverseiy relative to said margin.

5. A pack as claimed in claim 1 , wherein the two overlapping leaves are formed from a single piece of material folded on itself, the fold forming the join between the leaves.

6. A pack as claimed in claim 5, wherein at least one of the ends of the component is cut in the region of the fold to provide a starting point for tearing apart of the leaves.

7. A pack as claimed in any of the preceding claims, wherein the mutuaily facing inside surfaces of the leaves are joined together in localised spaced apart areas.

8. A pack as claimed in claim 7, wherein said surfaces are joined together by spots of adhesive.

9. A pack as claimed in claim 7, wherein said surfaces are joined together by stripes of peelable adhesive.

10. A pack as claimed in claim 7, wherein the stripes are at an oblique angle to an edge of the pack.

1 A pack as claimed in any one of the preceding claims, wherein the outer surfaces of the overlapping leaves are heat sealed to respective ones of the two elements.

12. A pack as claimed in claim 1 wherein each leaf has a laminated structure, the outer leaf surfaces being of material heat-sealable to the respective said element and the inner leaf surfaces being of material not heat-sealable together at the heat sealable temperature of the outer leaf surface material, thereby enabling formation of the leaf/element heat seals in one operation without heat sealing the leaves together.

13. A pack as claimed in claim 12, wherein the two elements are joined around said part of their peripheries by heat sealing simultaneously with the heat sealing of the opening component between the elements.

1 4. A pack as claimed in any preceding claim, wherein said two members are both of flat flexible plastics film.

15. A pack has claimed in any one of claims 1 to 13, wherein said one member is of flat flexible plastics film and the other member is of flexible plastics film formed as a tray.

1 6. A pack as claimed in any one of claims 1 to 13, wherein said one member is of flat flexible plastics film and the other member is of semi-rigid plastics sheet formed as a tray.

17. A pack as claimed in any one of the preceding claims, wherein the opening component is a strip and extends across a substantially straight edge of the pack.

18. A pack as claimed in any one of claims 1 to 16, wherein the opening component is located at a corner of the pack.

1 9. A pack substantially as hereinbefore described with reference to any of the accompanying drawings.

20. An opening component for incorporation in a pack as claimed in any preceding claim, comprising two overlapping leaves joined together along one margin of the component, The mutually facing surfaces of the leaves being of material which melts at a higher temperature than the material of the other surfaces of the leaves.

21. An opening component as claimed in claim 20, wherein the two overlapping leaves are joined together by a peelable adhesive.

22. An opening component as claimed in claim 21 , wherein the mutually facing inside surfaces of the leaves are joined together in localized spaced apart areas.

23. An opening component as claimed in claim 22, wherein said surfaces are joined together by spots of adhesive.

24. An opening component as claimed in claim 22, wherein said surfaces are joined together by stripes of peelable adhesive.

25. An opening component as claimed in claim 20, wherein the two overlapping leaves are formed from a single piece of material folded on itself, the fold forming the join between the leaves.

26. An opening component as claimed in claim 25, wherein at least one of the ends of the component is cut in the region of the fold to provide a starting point for tearing apart of the leaves.