Sealing Foil with Pull Tab

Abstract

A tearable foil for closing a package comprises a plurality of layers laminated together, including at least an oxygen barrier layer and a cover layer. A tear line penetrates at least partially through the cover layer to define a tear strip extending from a pull tab to a tail, wherein the pull tab comprises lateral wings that are delaminated with respect to the remainder of the foil, on either side of a central region that is laminated to the remainder of the foil. A user may fold the lateral wings together at right angles to a plane of the foil and grip them to exert a force on the central region and thus commence tearing of the tear strip.

Claims

1. A tearable foil for sealing a package, the foil comprising a plurality of layers laminated together, including at least an oxygen barrier layer and a cover layer, a tear line penetrating at least partially through the cover layer to define a tear strip extending from a pull tab to define a removable panel, wherein the pull tab comprises lateral wings that are delaminated with respect to the remainder of the foil, on either side of a central region that is laminated to the remainder of the foil, whereby a user may fold the lateral wings together at right angles to a plane of the foil and grip them to exert a force on the central region and thus commence tearing of the tear strip.

2. The foil according to claim 1, comprising a support layer below the oxygen barrier layer, the support layer preferably comprising polypropylene.

3. The foil according to claim 2, wherein the support layer comprises a cut in or adjacent to the central region to facilitate tearing of the foil at this point.

4. The foil according to claim 3, comprising a region of partial lamination surrounding the central region, where the lateral wings are weakly adhered to the remainder of the foil.

5. The foil according to claim 4, wherein the cut traverses the region of partial lamination and extends under the central region.

6. The foil according to any preceding claim, wherein the oxygen barrier layer comprises an aluminium layer.

7. The foil according to claim 6, wherein the tear line is cut through the cover layer by use of a laser and the aluminium layer serves to prevent deeper penetration of the laser.

8. The foil according to any preceding claim, wherein the support layer comprises a further barrier layer, preferably comprising EVOH.

9. The foil according to any preceding claim, wherein the cover layer comprises oriented PP.

10. The foil according to any preceding claim, wherein each wing has an area of at least 1 cm.sup.2, more preferably at least 2 cm.sup.2.

11. The foil according to any preceding claim, wherein the removable panel is encircled by a border.

12. A package comprising a tub having a base and a sidewall defining a product containing space, the sidewall terminating in a peripheral flange defining an access opening to the space and a foil according to claim 11, sealed at its border to the flange.

13. The package according to claim 12, further comprising a rim, the rim being connected to the flange with the foil sandwiched therebetween.

14. The package according to any of claims 13, further comprising a lid connected to the rim, the lid being pivotable between an open position and a closed position in which it closes the access opening.

15. The package according to claim 13 or claim 14, wherein the tub and the rim comprise polypropylene.

16. The package according to any of claims 12 to 15, wherein the flange is an outwardly extending flange.

17. The package according to any of claims 12 to 16, further comprising a quantity of a powdered nutritional product within the product containing space.

18. The package according to claim 17, wherein the product is infant formula.

19. A method of manufacturing a package, comprising: providing a tub having a base and a sidewall defining a product containing space, the sidewall terminating in a peripheral flange defining an access opening to the space; filling the space with a quantity of powdered nutritional product; providing a web of laminate material comprising at least a barrier layer and a cover layer; partially cutting through the laminate material to form a tear line extending through at least the cover layer, the tear line defining a tear strip having a pull tab and a removable panel, encircled by a border; connecting a section of the laminate material to the tub by joining the border to the peripheral flange to seal the package, whereby the tear strip overlies the access opening; and separating the section of laminate material from the web.

20. The method of claim 19, wherein the pull tab comprises a fully adhered central region, a partially adhered region adjacent to the central region and an unadhered gripping region.

21. The method of claim 19 or claim 20, wherein the section of laminate material is a foil according to any of claims 1 to 11.

22. A web of laminate material for use in the method according to any of claims 19 to 21, comprising a plurality of sections, each section preferably comprising a foil according to any of claims 1 to 11.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

[0026] The features and advantages of the invention will be appreciated upon reference to the following drawings of a number of exemplary embodiments, in which:

[0027] FIG. 1 shows a package incorporating the invention in perspective view;

[0028] FIG. 2 shows the package of FIG. 1 in exploded perspective view;

[0029] FIG. 3 a cross-section through FIG. 1, along line III-III;

[0030] FIG. 3A shows an enlarged detail of part of FIG. 3, illustrating the laminate layers'

[0031] FIG. 4 shows a plan view of part of the sealing foil of FIG. 2;

[0032] FIG. 5 shows a cross-section through the sealing foil of FIG. 4 along line V-V;

[0033] FIGS. 6 and 7 shows similar cross-section to FIG. 5 during operation of the pull tab;

[0034] FIG. 8 shows a schematic view of a manufacturing process for a web and packages incorporating the invention; and

[0035] FIG. 9 shows a plan view of the web of FIG. 9.

DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

[0036] FIG. 1 shows in perspective view a package 1 incorporating the present invention. The package 1 is in its completed state and includes a tub 2, enclosed by a sleeve 4, and a lid assembly 3.

[0037] FIG. 2 shows a partially exploded view of the package 1 showing in further detail the component parts of the package 1, including the tub 2, the sleeve 4, a foil 6, a lower rim 8, an upper rim 10 and a lid 12. The tub 2 is thermoformed of a laminate of inner and outer relatively thin polypropylene material layers and an intermediate EVOH barrier layer. It includes a base 14 and a peripheral wall 16 defining a product containing space 20. The peripheral wall 16 extends to an upper edge 18 having an outwardly directed flange 19. The sleeve 4 is formed of carton.

[0038] Lower rim 8 is formed as a flat annular ring of a similar dimension to the outwardly directed flange 19. The lower rim 8 is injection moulded of polypropylene, although it will be understood that other appropriate materials could also be employed. The upper rim 10 and lid 12 form the lid assembly 3 and are also formed of injection moulded polypropylene. The lid 12 is hingedly connected to the upper rim 10 at a hinge (not shown). The foil 6 includes a tear line 22 defining a tear strip 28 extending from a pull tab 26 to a tail 30. Within the tear strip 28 is a removable panel 24, while outside it is a border 44.

[0039] FIG. 3 is a partial cross-section through the package 1 in the direction of FIG. 1. FIG. 3 illustrates the location of the foil 6 between the flange 19 and the lower rim 8. In terms of construction, the border 44 of foil 6 is heat sealed to the flange 19 and welded by the use of ultrasound to the lower rim 8. Also shown in this view is a snap connector 32 at an outer edge of the upper rim 10, which is designed to mechanically engage with the lower rim 8 in an interference fit.

[0040] FIG. 3A is an enlargement of a portion of the seal 6 of FIG. 3, showing its construction. As can be seen, the seal 6 comprises a number of layers laminated together including a cover layer 34, an oxygen barrier layer 36 and a support layer 38. In the illustrated embodiment, the cover layer 34 comprises a 40 micron layer of oriented PP, the oxygen barrier layer 36 is a 9 micron thick layer of aluminium and the support layer 38 comprises a 40 micron thick laminate of PP/EVOH/PP. The EVOH layer 40 acts as a further barrier layer. The cover layer 34, oxygen barrier layer 36 and support layer 38 are laminated together by adhesive layers 42 of urethane adhesive. The tear line 22 extends through the cover layer 34 and terminates at the oxygen barrier layer 36. The use of aluminium for the oxygen barrier layer 36 allows the use of a laser to form the tear line 22 subsequent to lamination of the layer together to form the foil, since the aluminium prevents the laser from penetrating deeper into the support layer 38. Nevertheless, pin-pricks in the aluminium may occur and the use of the further barrier layer 40 ensures still that low oxygen permeability is maintained.

[0041] FIG. 4 is a plan view of a portion of the foil 6 of FIG. 2 in the region of the pull tab 26. The tear line 22 extends from the tear strip 28 around an outer perimeter of the pull tab 26 and defines a pair of lateral wings 50A, 50B. The wings 50A, 50B are delaminated with respect to the remainder of the foil 6 i.e. there is no adhesive 42 between the cover layer 34 and the oxygen barrier layer 36 beneath the wings 50A, 50B. Although in the present embodiment, the adhesive 42 is completely absent in this region, the skilled person will understand that it need not be completely absent to the extent that the wings 50A, 50B can be easily lifted or peeled away from the layer beneath.

[0042] Between the wings 50A, 50B is a spine or central region 52 in which the cover layer 34 is fully laminated. The central region 52 is aligned with the tear strip 28 and is surrounded by a region of partial lamination 54, where the wings 50A, 50B are less strongly adhered to the remainder of the foil 6. For the illustrated embodiment, in the region of full lamination under the central region 52, the peel strength of the adhesive 42 is around 3 N/15 mm ASTM F904. The wings 50A, 50B have a length of around 35 mm, meaning that a force of around 7 N may be exerted per wing before delamination occurs. In the region of partial lamination 54, the peel strength of the adhesive is around 2 N/15 mm ASTM F904. Also shown in FIG. 4 is cut 56, which extends beneath the region of partial lamination 54 in a direction generally following the central region 52 and extending from the tear strip 28 to a point where it passes under the central region 52.

[0043] FIG. 5 shows a cross-sectional view through the foil 6 in the direction V-V in FIG. 4, corresponding to the location at which the cut 56 first intersects with a margin of the central region 52. In this view, the relative positions of the tear line 22 through the cover layer 34 and the cut 56 through the support layer 38 can be seen. Also visible are the layers of adhesive 42 between the support layer 38 and the oxygen barrier layer 36 and between the oxygen barrier layer 36 and the cover layer 34. The former layer of adhesive 42 is continuous whereas the latter layer of adhesive 42 is interrupted at the delaminated region beneath the wings 50A, 50B where no adhesive is present. Furthermore, it may be noted that the cut 56 is directly below the margin of the central region 52 and is covered by the region of partial lamination 54. The presence of this region of partial lamination 54 helps ensure that any flaw in the oxygen barrier layer 36 at this point will still be covered by an adhered portion of the cover layer 34. Beneath the central region 52, a full layer of adhesive 42 is present.

[0044] FIG. 6 shows a view similar to that of FIG. 5 with the wings 50A, 50B raised to a position perpendicular to the foil 6. In this position, the region of partial lamination 54 is still adhered and overlaps the cut 56.

[0045] FIG. 7 shows a further view similar to that of FIG. 6, in which a user has gripped the pull tab 26 by grasping the wings 50A, 50B between thumb and fore-finger. On gripping and pulling the pull tab 26 upwards, the region of partial lamination 54 is caused to delaminate up to the point at which the central region 52 begins and the cover layer 34 is fully laminated to the oxygen barrier layer 36. Once delamination or peeling back of the wings 50A, 50B ceases, further upwards directed force on the pull tab is applied to the oxygen barrier layer 36, which will start to rip at the point at which it is least supported, namely the location of the cut 56. Initiation of the tear thus takes place at the position of line V-V in FIG. 4, at the two points where the cut 56 coincides with the margin of the central region 52. From there, the tear follows the cut 56 towards the tear strip 28 and once the cut 56 terminates, along the tear line 22 towards the tail 30. Based on the peel strength indicated above, a force of around 14 N may be applied without delamination occurring. Opening of the package may be achieved with a force of around 12 N due to the focussing of this force to the location of least resistance.

[0046] FIG. 8 shows schematically the manufacture of a web 60 of laminate material for use in manufacturing the foil 6 of FIG. 2. The web 60 comprises co-extensive layers corresponding to the layers described in relation to FIG. 3A, namely a cover layer 34, an oxygen barrier layer 36 and a support layer 38, laminated together by adhesive layers 42. During lamination of the web 60, adhesive layers 42 are deposited selectively by a printing device 62 such that at least the adhesive layer 42 between the cover layer 34 and oxygen barrier layer 36 has areas without adhesive corresponding to the locations of the wings 50A, 50B in addition to regions of partial lamination 54 as described above. Although shown as a single lamination step, in practice the cover layer 34 and the support layer 38 may be laminated to the barrier layer 36 in separate procedures at separate times and even locations.

[0047] Subsequent to lamination, the tear lines 22 and cuts 56 are applied using a laser cutter 64. In a subsequent phase, which may also take place at a different location, the web 60 is applied to tubs 2 at an automated filling and sealing station 66. Thereafter, the sealed tub 2 is separated from the foil 60 at a separating station 68.

[0048] FIG. 9 shows part of the web 60 of FIG. 8 in plan view at the location of the filling and sealing station 66 and the separating station 68. The web 60 comprises a number of sections 70, each having a tear strip 28 and pull tab 26. Each section 70 overlies a respective tub 2 whereby the border 44 is positioned above the flange 19 and is heat-sealed thereto. At the separating station 68, the web 60 is cut around the outside of the border 44 to separate the sections 70, leaving openings through the web 60. It will be understood that these steps may also be integrated and/or separating of the foil sections 70 may take place during sealing or just prior thereto.

[0049] The invention has thus been described in the context of the illustrated embodiment. It will be understood that many modifications in addition to those described above may be made to the structures and techniques described herein without departing from the spirit and scope of the invention. Accordingly, although specific embodiments have been described, these are examples only and are not limiting upon the scope of the invention.