ZA200602256B

ZA200602256B - Flexible packaging and method of manufacture

Info

Publication number: ZA200602256B
Application number: ZA200602256A
Authority: ZA
Inventors: Jeannin Bernard
Original assignee: Nestec Sa
Priority date: 2003-08-18
Filing date: 2006-03-17
Publication date: 2007-06-27
Also published as: CA2534881C; MXPA06001779A; EP1508530A1; AU2004264388B2; AR046007A1; WO2005016781A1; AU2004264388A1; BRPI0413605A; CN1835871A; US20070269146A1; RU2006108545A; RU2330797C2; JP2007502753A; CA2534881A1; JP2011042408A

Description

NO 7501 “FLEXIBLE PACKAGING AND METHOD OF MANUFACTURE"

LD OF Oo

This invention relates to flexible packaging —umits intended. to be opened by tearing and to means for controlling the opening by t-earing. The invention provides a method of constructing 2 flexible packaging unit teo facilitate controllable opening thereof by tearing. Further, the invention proviedes a flexible packaging unit incorporating tear control means for facilitating its comntrollable opening.

BACKGROUND OF THE

Being able to control the opening of a flexible container such as a plastic bag or pouch is important to consumers, especially wheres the contents are likely to mess if spilt. Means for controlling the direction of tearing eof a tearable packaging unit have been previously proposed. In US 5,186,543 there iss disclosed an easy-open flexible container having guide strips respectively located o=n either opposed side wall and a tear strip located at the apex of the container. Extesnding from the tear strip to each guide strip is an opposing tear area defined on eacl wall. Tearing is limited to these areas when the consumer takes hald of and pulls thhe tear strip from onc 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 fhe plastic film that makes up the wall; the strings being pullable to open the pouch. Aa drawback of this invention too is the requirement of providing special elements, in this case the strings, adding complexity to the manufacture thereof. -l-

CONFIRMATION COPY

NO 7501

EP 0325993 de scribes a bag having a tear strip that is defined by paralle=1 perforated lines. The perforations are backed by a sealing strip to maintain the hermetic integrity of the bags inteerior. Again, this invention has the drawback of increasing complexity of manufacture .

EP 0423456 d3scloses a bag having zipper means rendering it reclosabe and a tear strip for facilitating the initial opening. The tear strip can be located imaternally and externally at the apex of the bag. Protection against unwanted propagatieon of the tear towards the zipper elements is achieved by providing the zipper elements= each with an extended base- portion to reinforce the film of the walls and to keep =the tear from reaching down to them. This invention adds further to the material req uirements for manufacture.

There is a nee=d for a bag or other flexible container construction of simpole, yet having means of prev-enting propagation of an initial tear in an undesired direction or area.

An advantages of the present invention is to provide a container having & bounded tear area in whichm tearing is confined in a construction that avoids having =a 1ear strip. By setting limits to the area available for tearing and defining such area emntirely within a wall of the container, the problem of the tear propagating off the top edge of the container, lea. ving the mouth not completely opened, is avoided.

An advantagee of the present invention is to provide barrier means for preventing the tear from pro=pegating to the top edge of the container.

SUMMARY" OF INVENTION

According teo a first aspect of the invention, there is provided a fle=xible container comprising Opposed front and back walls sealed together proximate teo their edges to define an intemal space, a pair of tear-limiting strips applied to a surfeace of each wall or located wwithin each wall so that the strips on or within opposed. walls coincide substantiallyw, defining corresponding tear paths.

NO 7501

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 0.1mm to about 6mm apart, preferably about 1mm-2mm and further preferably from about 1.2mm to 1.8mm.

In a further preferred form of the invention, the strips of each pair are located to be substantially parallel to each other.

In an embodiment, 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 Imm to about 5mm in breadth, preferably from about 1.5mm - 2.5mm.

Further according to the invention, the strips —amay all be located on the outer surface oF the walls. Alternatively, the strips are all loc=ated on the inner surface of the walls. Ira 209 an embodiment, one pair of strips is located on an inner wall surface and the other ora an outer wall surface. In another embodimes=nt, one strip in each pair is located on am inner surface and the other strip is located <n an outer sutface of each wall. In thee event the wall is comprised of a laminate nomaterial, a strip may be located to be on .a surface between laminate materials making ump the wall material.

In preferred cmbodiments, the thickness of the strips is in the range from about 12 — 100 microns, preferably about 20-50 micronss.

Further according to the invention, the strips: are made of polypropylene (PP). 3€0 Alternatively, the strips may be made of pol=yethylene (PET).

NO 7501

According to a second aspect of the invention, there is provided a flex=ible-walled container having opposed back anc front walls, each wall 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 withimn each wall, defining a tear path located to be s=paced from at least a part of the top edge= thereof

In a preferred form of the invention, the tear paths are defined by paired spaced barrier strips resistant to tearing.

According to a third aspect of the invention, a method of manufacturimg a flexible walled container comprises the ssteps of providing first and second films, providing tear barrier material in strip form, applying the tear barrier material in p=aired strips to each film so as to define a substantially coinciding tear path on each and aranging the films in opposition to form a comtainer comprising substantially coincidming tear paths on each wall.

The invention further provides an method of manufacturing a sealable ba=g, the method comprising the steps of providing a flexible film and forming it int-© a container ’ defining an intemal space bounced by respective front and back walls, sand applying a 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 substantial 1y greater tear resistance than the flexible film to which it is applied.

DES ON OF D.

Figure 1 presents in A a side —view of an embodiment of a flexible container of the invention and in B a cross sectiaon of the container along line A-A’.

Figure 2 is a side view of an altzemative embodiment of the invention.

NYO 7501

Figure 3 is a side view of a further alternative embodiment of the invention.

Figure 4 is a schematic illustration of a process of manufacture of a container according to the invention.

FDOETAILED DESCRIPTION OF EMBODIMENTS

“The invention provides for the definition of substaratially coinciding tear paths on -opposing walls of a flexible packaging unit made ofa tearable film, for example a film of plastics material or a laminate. The tear path is designed to facilitate the opening of the container in a controllable manner by a consumer desirous of accessing the contents. By limiting the propagation of the opening tear to a defined path, a cleaner open may be obtained and the likelihood of spillagce, waste and messing reduced. The packaging unit may be a pouch container or a bag or the like.

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 sub stantially parallel to each other. The barrier strips may be applied to the inner or outer surfaces of the container and in any combination. In a preferred embodiment, the strips are all applied to the outer surfaces at corresponding positions. However, they may also be applied to the opposing inner surfaces. Alternatively, one pair may be applied £0 an inner surface and the other to the outer surface of the opposing wall. In an emb-odiment, one strip in a pair may be applied to an outer surface while its partner may toe applied to the inner surface of the same wall. Where the wall is constructed of a laraninate material, one of more of the strips may be located between adjacent layers in £he laminate.

The strips are preferably spaced apart from aboutz 0.1xom to about 6mm and further preferably from about 1mm to about 2mm. In a particularly preferred embodiment, the strips are spaced apart by about 1.3mm to about 3.8mm.

NO 7 501

By nearnowing the spacing between the strips in each pair and by making the posit=ioning of the pairs coincide on the opposing walls, a near pe=xfect tear line is achie=vable with the tear paths on the opposing walls almost exac=tly superposed.

The =strips are comprised of tear tape that is sealable or preferably self adhesive.

Eacln strip desirably may have a width in the range from about 13mm to Smm, preferably from about 1.5mm to about 2.5mm. Desirably the strips have a thickness in the range from about 12 microns to 100 microns, preferably frormn about 20 to about 50 micmons. Factors such as strip thickness, strip width and grade Of strip tape material will determine the strip tear resistance in comparison with the tear resistance of the filom from which the container is fashioned.

In tHe case where the containers are to be retorted or subjected sto a form of heat treatment, the strips are preferably made of polyester or polyethylene (PET). Where the containers are intended to house a dry product and not be stabjected to a retort stage, they may conveniently be made from polyproylene (PP) tape. Polyester tape ma-y however also be used, as may other suitable tape materialss known in the art.

Thee pouches may conveniently be of the doypack type or be 3— or 4-sidedly sealed pouches. However, other pouch configurations may be emplo=yed. The pouch material ma=y be PP, PET and laminates comprising two or more of PP, metallised foil, e.g. alumminium foil (Alu), poly-acrylamide (PA), PET, fibre sheeting, such as paper, and

PE=. Preferably it will be a 3-layer laminate of PET/AIWPP fom retorted product applications, and PET/PP or PP/PE for dry product applicatioras. Further layers may be added, depending on the product application and processing and the degree of tear resistance required in comparison with the tear-limiting strips to be applied.

Te facilitate the initiation of a tear, a notch may be formed at an edge of the container weall. Alternatively, a hole may be punched at a suitable location where the opposed waalls are sealed together. The notch or hole is sealed around. its edges to maintain the aimrtight integrity of the container. The tear limiting tape strip may be applied to each siecle of the notches or punched holes.

NO 7501

The flexible ~container 10 illustrated in Figure 1 has opposing walls 12, 14 sealed together at region 16, proximate to top edges 18, 20. Below regi «on 16 and spaced from top edges 18,. 20 is barrier strip 22, 24 applied extemally to time wall 12, 14. Spaced from barrier sSatrip 22, 24 is a second bamier strip 26, 28. Between the upper and lower barrier strips is defined thus a tear area 30, 32. A notch 34 ies provided to facilitate initiation of am tear in the tear area. When a tear 36 is initiated in tear area 30, 32, itis forced to progpagate in that tear area defined by the barrier stripss, and not stray beyond.

The direction. and extent of tearing is thus controllable.

Figure 2 illusstrates in cross section an embodiment of laminatec wall sections to which barrier strips are applied, according to the invention. Like mmumerals are applied to denote like f=eatures appearing in figure 1. In this embodiment, tear barrier strips 22, 24, 26 and 238 are located internally in walls 12 and 14, being 1olaced between adjacent layers of aliuminium foil 38 and polypropylene 40. An external layer 42 of polyethylene= PET is applied over the aluminium foil 38. The layers are sealed together at hmeat seal 44.

Figure 3 illu=states 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 pol yethylene surfaces of layers 42.

A wall matexial for a tearable flexible container of the invention may be manufactured by providing a flexible film for forming a wall of the container, such as a laminate of alufoil and poolyethylene, providing a tear barrier element hav-ing substantially greater tear resistarmce than the wall film, for example a polyprop=ylene 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 form may be adhered to the film through use of an adhesive, or may be thermally bonded to it.

Figure 4 illiastrates a method of manufacturing a laminated flexible sheet material foil for use in foming the bag of figure 1. In the illustrated exe-xnplary embodiment, the

NO 7501 walls 12, 14 are constructed of a laminated sheet comprisirmg a foil 42 on a polyethyleme film 44. The tear barrier comprises polyethylene strips 22, 26 applied to the foil 42_ The foil is preferably metallised and may for exampmle be an aluminium foil (“alufo il”).

In a prefexred embodiment, as the laminated sheet 40 is mowed by means of a conveyor szystem, the barrier strips are of polyester and optionally covered by a layer 46 of polypropylene extruded over them. In figure 2, the polyp-xopylene layer 46 is applied by means of an extrusion hopper 48. Irregularities 50 in lemyer 46 are smoothed out by passsing the layer under a comecting roll 52. The adhesive - on the strip is a self- adhesive rmaterial delivered in reel. No high temperature treatment is needed for the applicatiorm which is done by simple contact by unwinding a tape while unwinding the film. The strip and its applicator are obtainable from the cormpany PP Payne of

Nottingharm, England.

An advant.age of the invention is that it provides a highly reliablee guided tear in both opposing =walls of the container, along a bounded path leadingg from one edge to another, bez it from a side edge to the opposite side edge or from the top edge to a side edge or frcam a side edge to a defined part of the top edge.

A further sadvantage is that the package and the guide strips defining the tear path are all retortatsle. :

Claims

“NWO 2005/016781 PCT/EP=2004/009251 NO 7501 CLAIMS:

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

2. The container of claim 1 wherein the strips of each pair are spaced fmrom about

0.1mm to about 6mm apamrt.

3. The container of claim 2 wherein the strips of each pair are spaced fiom about Imm-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 subsstantially 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 cof claims 1 to 5 wherein the strips are self-acihesive.

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

9. The container of claim 8 v=vherein the strips are about 1.5 — 2.5mm in bmreadth.

10. The container of any one of the preceding claims wherein the walls co-mprise a laminate material.

NO 7501

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

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

13. The container of any one of claims 1 to 10 wherein one pair of strips is located on an internal wall sumrface and the other on 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 fron walls, each having a respective top ecige, the walls being sealed togethems proximate to the respective top edges defining an internal space between th_em, 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 iss manufactured from a material more tear—resistant than the material of the walls.

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

18. A container as clairsaed in claim 15 or claim 16 wherein ®@he tear path extends from an end of a wa ll to the top edge.

19. A container as claSmed in any one of claims 15 to 18 wherein the or each element is located beetween adjacent layers in a laminate w=all.

NO 7501

20. A method of forming a wall material for a tearable flexib-le container comprising the steps of providing a flexible film for forming ax wall of the container providing a tear barrier element h=aving substantially greater tear re=sistance 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 sezalsble bag comprising the steps oof providing a flexible film and forming it into £3 container defining an internal s=pace bounded by respective front and back walls, and applying a tear barrier strilip to the walls to define a bounded tear path on eeach of the front and back walls.

22. A method according to claim 21 comprising applying a pair of st—xips located to RS be substantially parallel to eaclm other, the strips having substa—ntially greater tear resistance than the flexible Alm.

23. A method according to claim 222 wherein the strips are locate to be spaced from about 0.1mm to about 6mn apart.

24. A method of manufacturing a flaexible walled container comprising the steps of providing first and second filmss, providing tear barrier material in strip form, applying the tear barrier material in paired strips to each film sc as to define a substantially coinciding tear patTh on each and arranging the filma s in opposition to form a container comprising ssubstantially coinciding tear path _s on each wall.

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

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

NO 7501

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