CA2534881A1

CA2534881A1 - Flexible packaging and method of manufacture

Info

Publication number: CA2534881A1
Application number: CA002534881A
Authority: CA
Inventors: Bernard Jeannin
Original assignee: Individual
Current assignee: Nestec SA
Priority date: 2003-08-18
Filing date: 2004-08-17
Publication date: 2005-02-24
Anticipated expiration: 2024-08-17
Also published as: US20070269146A1; AU2004264388A1; AR046007A1; MXPA06001779A; JP2007502753A; RU2006108545A; EP1508530A1; AU2004264388B2; CN1835871A; WO2005016781A1; BRPI0413605A; RU2330797C2; ZA200602256B; JP2011042408A; CA2534881C

Abstract

A wall material for a construction of a flexible container that is designed to be openable by tearing is formed by providing a flexible film for forming a wall of the container, providing a tear barrier element having greater tear resistance than the wall film, locating the element on or within the film to define a tear path thereon, and fixing the element to the film. The film is then arranged to form a flexible-walled container having opposed back and front walls, so that the tear path is spaced from at least a part of the top edge thereof and facilitates opening of the container by restricting tearing to the path defined between the strips. The tear barrier strips may be located to be fixed on the film by means of suitable adhesive or may be embedded between laminate layers of the wall material.

Description

NCa 7501 '~FLE~II~LE T'ACI~AG~hIG AND ME~'HQD OF lVIAIVU~'ACTt;~"
FIELD ~F TNVENTIC3N
This invention relates to flexible packaging units intended. to be opened by tearing and to means for controlling the opening by tearing. The invention provides a method of constructing a flexible packaging unit to facilitate controllable opening thereof by tearing. Further, the invention provides a flexible packaging unit incorporating tear control mews for facilitating its controllable opeung.
EACTC~'rRC'UND t>F TF-IE INVEI~ITIC~N
Being able to control the opening of a flexible container such as a plastic bag or pouch is important to consumers, especially wlxere the contents are likely to mess if spilt. Means for controlling the direction of tearing of a tearable packaging unit have been previously proposed. In IJS 5,186,543 there is disclosed an eas~T-open flexible container having guide strips respectively located on either opposed side wall and a tear strip located at the apex of the container. Extending from the tear strip to each guide strip is an opposing tear area defined on each wall. Tearing is limited to these areas v~.~hen the consumer takes hold of and pulls the tear strip from anc side to the other. A drawback of this invention is that a special tear strip has to be provided and incorporated into the construction.
European patent EP 0471220 discloses a pouch having a thin-walled part for easy tearing, the thin wall part incorporating strings in the plastic film that makes up the wall; the strings being pullable to open the pouch. A drawback of this invention too is the requirement of providing special elements, in this case the strings, adding complexity to the manufacture thereof:
CONFIRMATION COPY

NCB 75~ I
EP 0325993 describes a bag having a tear strip that is defined by parallel perforated lines. The perforations are backed by a sealing strip to maintain the hermetic integrity of the bag's interior. Again, this invention has the dxawback of increasing cozrzplexity of manufacture.
EP 0423456 discloses a bag having zipper means rendering it reclosable and a tear strip for facilitating the initial opening. The tear strip can be located internally and exterz~tally at the apex of the bag. Protection against unwanted propagation of the tear towards the zipper elezxzents is achieved by providing the zipper elements each with an extended base portion to reinforce the fzlm of the walls and to keep the tear frozrz reaching down to tl~xem. This invention adds further to the material requirements for manufacture.
Them is a need for a bag ar other flexible container oonstruotion of simple, yet having zrzeans of preventing prapagatian of an initial tear in an undesired direction or area.
An advantage of the present invention is to provide a container having a bc~.nd~d tear area in which tearing is confined in a construction that avoids havin'T a teL-Grip. B~-setting limits to the area available far tearing and defining such area entirelw within a wall of the container, the problem of the tear propagating off the top edge of the container, leaving the mouth not completely opened, is avoided.
An advantage of the present invention is to provide barrier rxzeans far preventing the tear frarn propagating to the tap edge of the container.
SUMMARY OF INVENTION
According to a fZrst aspect of the invention, there is provided a flexible container comprising opposed front and back walls sealed together proximate to their edges to 3C1 define an internal space, a pair of tear-limiting strips applied to a surface of each wall or located within each wall so that the stzips on or within opposed walls coincide substantially, definiz~:g corresponding tear paths.

To be tear-limiting, the strips have substantially greater tear resistance than the walls.
In a preferred form of the invention, the strips of each pair are spaced from about S O.lmm to aboczt 6zxzzn apart, preferably about 1mm-2mm and further preferably froze about 1.2mm to l.8zrzrrz.
1n a further preferred form of the invention, the strips of each pair are located to be substantially parallel to each other.
In an embadiznent, the strips comprise sealable strips.
In an embodiment, the strips are self adhesive.
In a still further preferred form of the invention, the strips are about 1 mm to about Smm in breadth, preferably from about l.Smm - 2.Smm, Futtlzer according to the invention, the strips znay all be located on the outer suefac~ ~ f the v,Jalls. Alternatively, the strips are all located an the inner surface of the walls. In an embodiment, one pair of strips is located an an inner wall surface and the other on an outer wall surface. In another embodiment, one strip in each pair is located on an izmer surface and the other strip is located on an outer surface of each wall.
In the event the wall is comprised of a laminate material, a strip zxzay be boated to be on a surface between laminate materials making up the wall material.
In preferred embodiments, the thickness of the strips is in th.e range from about I2 -100 znicrans, preferably about'~0-~0 rnicrozzs.
Further according to the invention, the strips are made of polypropylene (PP).
3fl Alteznatively, the strips may be made of polyethylene (PET).

ITC? '501.
According to a second aspect of the invention, there is provided a tlexibleAwalled container having opposed back and front walls, each wall having a respective top edge, the twalls being sealed together proximate to the respective top edges defining an internal space between them, and tear barrier means provided on or within each wall, defining a tear path Located to be spaced from at least a part of the tap edge thereof In a preferred farm of the invention, the tear paths are defined by paired spaced barrier strips resistant to tearing.
Acaordixzg to a third aspect of the invention, a method of rxjanufacftxring a flexible walled container comprises the steps of providing first and second films, providing tear barrier material in strip farm, applying the tear barrier material in paired strips to each film so as to define a substantially coixxciding tear path on each and arranging the films in apposition to form a container comprising substantially aainciding tear paths 1 ~ on each wall.
The invention further provides a method o~ manufacturing a sealable bag, the method comprising the steps of providing a flexible fxhn and forming it into a container defining an internal space bounded by respective front and back walls, and applying a 2(1 tear barrier strip to the walls to define a bounded tear path on each of the front and back walls.
In all embodiments of the invention, the tear barrier is of substantially greater tear resistance than the flexible film to which it is applied.
BRTEF DESCRIPT101rT CF I~I~AW1NGS
Figure 1 presents in A a side view of an embodiment of a ffexible container of tlae invention arid in B a crass section of the container along line A-A'.
Figure z is a side view of an alternative embodiment of the invention.
_q._ NO 701.
Figure 3 is a side view of a fiirther alternative embodiment of the invention.
Figure A~ is a schematic illustration of a process of manufacture of a container according to the inVent1013.
DETAILED DESCRIPTION OF EIvI$0r3IMENT~
The invention provides for the definition of substantially coinciding tear paths on opposing walls of a flexible packaging mit made of a tearable film, for example a film of plastics material or a laminate. The tear path is designed to facilitate the opening of 1Q the container in a controllable manner by a consumer desirous of accessing the contents, Ey limiting the propagation of the opening tear to a defined path, a cleaner open may be obtained and the likelihood of spillage, waste and messing reduced. The packaging unit may be a pouch container ar a bag or the like.
1 S The tear paths are defined by applying tear limiting elements in the form of barrier strips in pairs to the surfaces of the container walls or to sheets in laminated material making up the walls. Preferably the strips are substantially parallel to each other. The barrier strips may be applied to the inner or outer surfaces of the container and in an~~
combination. In a preferred embodiment, the strips are all applied to the outer surfaces 20 at corresponding positions. However, they may also be applied to the opposing inner surfaces. Alternatively, one pair may be applied to an inner surface and the other to the outer surface of the opposing wall. In an embodiment, one strip in a pair may be applied to an outer surface while its partner may be applied to the inner surface of the same wall. Where the wall is constructed of a laminate material, one of more of the 25 strips may be located between adjacent layers in th.e lalninats.
The strips are preferably spaced apart from about ~. lnnn to about 6tnin and further preferably from about 1 mm to about ~mrn. In a particularly preferred embodiment, the strips are spaced apart by about l.3mm to about l.8mzn.

By zzarrowing the spacing between fihe strips in each pair arid by making the positioning of the pairs coincide on the opposing walls, a near perfect tear line is achievable with the tear paths on the opposing walls alzzz,ost exactly superposed.
S The strips are comprised of tear tape that is sealable or preferably self adhesive.
Each strip desirably may have a width in the range from about Imm to Snzzn, preferably from about I .Smm to about 2.Smm. Desirably the strips have a thicklzess in the range from about 12 microns to lOfl microns, preferably from about 2Q to about S4 microns. Factors such as strip thickness, strip width and grade of strip tape material I O will determine the strip tear resistance in comparison with the tear resistance of the film from which the container is fashioned.
In the case where the containers are to be retorted or subjected to a form. of heat treatment, the strips are preferably made of polyester or polyethylene (fET).
Where I S the containers are intended to house a dry product and not be subjected to a retort stage, they may conveniently be made from polyproylene (IMP) tape. Polyester tape may however also be used, as may other suitable tape materials known in the art.
The pouches may conveniently be of the doypacl~ type or be 3- or 4-sidedly sealed 20 pouches. However, other pouch configurations may be employed. The pouch material may be fF, fET arid Iarninates compzxsing two or more affP, metallised foil, e,g.
aluminium foil (Alu), poly-acryIamide (PA), PET, fibre sheeting, such as paper, and fE. Preferably it will be a 3-layer laminate of PET/Alu/PP for retorted product applications, and PETlP'P or PfIPE for dry product applications. further layers may 2S be added, depending on the product application and processing and tlxe degree of tear resistance required in comparison with the 'tear-limiting strips to be applied.
To facilitate the initiation of a tear, a notch may be formed at an edge of the container wall. Alternatively, a hole may be punched at a suitable location where the opposed 30 walls are sealed together. The notch or hole is sealed around its edges to maintain the airtight integrity of the container. The tear limiting tape strip may be applied to eaoh side of the notches or punched holes.
,.C_ 1'10 '~5CI1 The flexible container ltl illustrated in Figure I has opposing walls 12, 14.
sealed together at xegion 1G, proximate to top edges I $, 20. Below region I6 and spaced from tap edges 1 S, 20 is barrier strip 22, 24 applied externally to the wall 12, 14. Spaced from barrier strip 22, ~4 is a second barrier strip 26, 2$. Between the upper and lower bal-rier strips is defined thus a tear area ~0, 32. A notch 34 is provided to facilitate initiation of a tear in the tear area. 'then a tear 36 is initiated ;n t~hr ~~p~ ~zn ;o ;+ ;
forced to propagate in that tear area defined by the barrier strips, and not stray beyond.
The direction and extent of tearing is thus controllable.
Figure 2 illusta~ates in crass section an embodiment of laminated wall sections to which barrier strips are applied, according to the invention. I,i~e numerals are applied to denote like features appearing in figure I. In this exnbodinaent, tear barrier strips 2~, 24, 25 and 28 are located internally in walls 12 and I4, being placed between adjacent layers of aluminium foil 3$ and polypropylene 40. An external layer 42 of polyethylene PET is applied over the altuninium foil 3$. The layers are sealed together at heat seal 44.
Figure 3 illustrates a further exemplary embodiment, in which the barrier strips 22, 24, 26 and 28 are placed externally to the container, being applied as self adhesive tape to the outer polyethylene surfaces of layers 42.
A wall material for a tearable flexible container of the invention may be manufactured by providing a flexible film far forming a wall of the container, such as a laminate of 2S alufoil and polyethylene, providing a tear barrier element having substantially greater tear resistance than the wall film, for example a polypropylene tape, locating the element on the film to define a tear path thereon, and fixing the element to the film.
The barrier element in strip forzu may be adhered to the film through use of an adhesive, or may be thermally bonded to it.

Figure 4 illustrates a method of manufacturing a laminated flexible sheet material foil for use in farming the bag of figure I. In the illustrated exemplary embodiment, the NU '75GI
walls 12, I4 are constructed of a laminated sheet comprising a foil ~.2 on a polyethylene film 44. The tear barrier comprises polyethylene strips 22, 26 applied to the foil ~~. The foil is preferably metallised and may for e~an~ple be an al~zzz~inizun foil {'talufoil").
S
In a preferred embodiment, as the Iamizxated sheet ~0 is moved by means of a conveyor system, the barrier strips are of polyester and optionally covered by a layer 4& of polypropylene extruded aver them. In figure ~, the polypropylene layer 4C is applied by means of an e:~trusian hopper 48. Irregularities 50 iz~z layer ~~6 are smoothed I O out by passing the layer under a eoxreeting roll 5~. The adhesive an the strip is a self adhesive material delivered in reel. No high tezx~perature treatznant is needed far the application which is done by simple contact by unwinding a tape while unr~inding the film. The strip and its applicator are obtainable frazxz the company PP Payne of Nottingham, England.
IS
An advantage of the invention is that it provides a highly reliable guided tear in both opposing walls of the container, along a bounded path leading from one edge to another, be it from a side edge to the opposite side edge or from the top edge to a side edge or from a side edge to a defined part of the top edge.

A further advantage is that the paclcage and the guide strips defining the tear path are all retartable.
~g_

Claims

1. A flexible container comprising opposed front and back walls sealed together proximate to their edges to define an internal space, a pair of tear-limiting strips applied to a surface of each wall so that the strips coincide substantially on the opposed walls, defining corresponding tear paths along each surface.

2. The container of claim 1 wherein the strips of each pair are spaced from about 0.1mm to about 6mm apart.

3. The container of claim 2 wherein the strips of each pair are spaced from about 1mm-2mm apart.

4. The container of claim 3 wherein the strips of each pair are spaced from about 1.2mm to 1.8mm apart.

5. The container of any one of the preceding claims wherein the strips of each pair are located to be substantially parallel to each other.

6. The container of any one of the preceding claims wherein the strips comprise sealable strips.

7. The container of any one of claims 1 to 5 wherein the strips are self-adhesive.

8. The container of any one of the preceding claims wherein the strips are about 1mm to about 5mm in breadth.

9. The container of claim 8 wherein the strips are about 1.5 - 2.5mm in breadth.

10. The container of any one of the preceding claims wherein the walls comprise a laminate material.

11. The container of any one of the preceding claims wherein the strips are all located an the outer surface of the walls.

12. The container of any one of claims 1 to 10 wherein the strips are all located on the inner surface of the walls.

13. The container of any one of claims 1 to 10 wherein one pair of strips is located on an internal wall surface and the other an an external wall surface.

14. The container of claim 10 having a pair of strips located within the laminate material.

15. A flexible-walled container having opposed back and front walls, each having a respective top edge, the walls being sealed together proximate to the respective top edges defining an internal space between them, and tear barrier means provided on or within each wall, defining a tear path located to be spaced from at least a part of the top edge thereof.

16. The container of claim 15 wherein the tear barrier means is manufactured from a material more tear-resistant than the material of the walls.

17. A container as claimed in claim 1 wherein the tear path extends from one end to the other across the hack and front walls.

18. A container as claimed in claim 15 or claim 16 wherein the tear path extends from an and of a wall to the top edge.

19. A container as claimed in any on a of claims 15 to 18 wherein the or each element is located between adjacent layers in a laminate wall.

20. A method of forming a wall material for a tearable flexible container comprising the steps of providing a flexible film for forming a wall of the container providing a tear barrier element having substantially greater tear resistance than the wall film, locating the element on the film to define a tear path thereon, and fixing the element to the film.

21. A method of manufacturing a sealable bag comprising the steps of providing a flexible film and forming it into a container defining an internal space bounded by respective front and back walls, and applying a tear barrier strip to the walls to define a bounded tear path on each of the front and back walls.

22. A method according to claim 21 comprising applying a pair of strips located to be substantially parallel to each other, the strips having substantially greater tear resistance than the flexible film.

23. A method according to claim 22 wherein the strips are located to be spaced from about 0.1mm to about 6mm apart.

24. A method of manufacturing a flexible walled container comprising the steps of providing first and second films, providing tear barrier material in strip form, applying the tear barrier material in paired strips to each film so as to define a substantially coinciding tear path on each and arranging the films in opposition to form a container comprising substantially coinciding tear paths on each wall.

25. A method according to claim 24 comprising applying the paired strips to be spaced from about 0.1mm to about 6mm apart.

26. A method according to claim 24 or claim 25 wherein the films comprise a laminate of alufoil and polyethylene.

27. A method according to any one of claims 24 to 26 wherein the strips comprise a tape of polyester, polyethylene or polypropylene.