GB2332899A

GB2332899A - Easy tear bag

Info

Publication number: GB2332899A
Application number: GB9800118A
Authority: GB
Inventors: Luen Sing Tang
Original assignee: Tecksom International Ltd
Current assignee: Tecksom International Ltd
Priority date: 1998-01-05
Filing date: 1998-01-05
Publication date: 1999-07-07
Also published as: GB9819497D0; TW359652B; GB9800118D0; GB2332900A

Abstract

Bags are disclosed having a front and a back, with two abutting strips of material situated in between. The interface between the abutting parallel strips creates a thin straight channel ("tearing line") in the bag, along which a tear is naturally guided. This allows the bag to be opened easily. There may be aligned layers of abutting strips. A nick may be provided to aid commencement of the tear. The abutting strips may be of different materials and may be narrow as shown or wider pieces of material such as a wide transparent strip and a narrower metallised strip. There may also be means for resealing the opened bag.

Description

EASY TEAR BAG This invention relates to bags which can be opened easily, without the need for scissors, for instance.

The waterproof, air-tight and durable nature of plastic bags means that they are widely used for packaging goods. Various ways for facilitating the opening of such bags are known. The simplest approach is to print a line on the bag to indicate where an opening should be cut.

This cut might open directly onto the contents of the package (eg. Figure 1) or it might open onto a spout integrated into the package (eg. Figure 2; see also US patents 4491245,4793121 & 4935283 and the "AmpacTM spout-pack"). Such a spout also makes a convenient opening for the insertion of a drinking straw.

Bags are also available which can be opened without the need for scissors. Whilst this can be achieved very easily by simply perforating the intended opening, this is not suitable where the package must be kept air-tight (eg. liquids or perishable goods). "EasyCut" packaging (marketed by CLP-GAL Industries in Israel) uses an invisible mark on the package which creates an air-tight perforated line. EasyCut packaging can be opened by simply tearing along this invisible line.

It is also known to integrate a guide wire or string into a package which, when pulled, opens the package (eg. Figure 3). Another system incorporates two strong parallel tracks into the plastic which define a channel between them (eg. Figure 4). The end of this channel typically contains a nick in the plastic. When tearing begins at this nick, the two tracks guide the tear down the channel, giving a straight tear.

These tearing systems can also be integrated into re-sealable bags. Once the tear has been made, the bag can still be re-sealed by means of a zip-lock, for instance (eg. Figure 5). This gives a tamper-proof re-sealable bag.

It is an object of the invention to provide further means for facilitating the opening of packages. It is a further object to provide easy-tear packages which can be manufactured at relatively low cost.

According to the invention, there is provided a bag with a front and a back, with two abutting strips of material situated between the front and the back, the line of abutment constituting a tearing line.

The interface between the abutting parallel strips creates in effect a thin straight channel ("tearing line") in the bag, along which a tear is naturally guided. This allows the bag to be opened easily.

If desired, there may be more than one layer of abutting strips between the front and the back of the bag. For instance, a bag Id be formed from two sheets of laminated plastic material, both of which comprise a layer consisting of abutting strips of material. These two sheets can be juxtaposed such that the layers comprising abutting strips are both between the front and back of the bag, with their lines of abutment aligned (ie. essentially co-linear, but possibly deviating slightly eg. within 1 mm). This creates, in effect, a composite tearing line.

A suitable laminated plastic material which contains a tearing line is one which may be made using the method as disclosed in International Patent Application PCT/GB97/02836 (copy attached as Annex I). Briefly, the laminated plastic comprises a base layer onto which are adhered a plurality of parallel strips of material which abut and do not overlap. An example of a suitable laminated plastic material, which also comprises a third layer, such that the abutting parallel strips are sandwiched, is shown in Figure 6, and this type of material is used in the most preferred embodiments of the invention.

In preferred embodiments, one end or both ends of the tearing line contains a small opening, break, nick, notch or the like. This facilitates the initiation of a tear. The tearing line may be visibly indicated on the bag, for example by printing a perforated line at the relevant position.

The bag is preferably sealed around its edges. Whilst it is preferred not to seal along the full length of the tearing line, since this could result in the bag remaining sealed even after being torn "open", the bag may be sealed across the tearing line beyond that necessary simply to seal the edges of the bag. When such a bag is tom open, rather than the bag becoming completely open, a smaller opening is exposed which allows the contents of the bag to be poured more easily, in the same way as a spout.

It will be appreciated that the laminated plastics which are used to make the bag may comprise more than two layers. For instance, whilst they might comprise just a base layer and a layer of abutting parallel strips, they might also comprise a further layer, covering and protecting the abutting parallel strips, for instance. Furthermore, the plastics will typically be over-printed with a desigr 7r pattem. The front and back of the bag need not, of course, be made from the same mateiJ.

The parallel abutting strips within the laminated plastic may be made from the same or different material. For instance, both strips could be transparent, or one strip could be metallised whilst the other is transparent.

In addition, bags according to the invention may incorporate means for re-sealing an opened bag, such as a zip-lock.

The invention will now be described by way of examples, with reference to the accompanying drawings, in which: - Figures 1-5 illustrate systems used in the prior art for facilitating the opening and re-sealing of bags; - Figure 6 illustrates a laminated plastic material which can used to make bags according to the invention; and - Figures 7-10 illustrate the manufacture of bags according to the invention.

In a first embodiment, shown in Figure 7, using the methods described in International Patent Application PCT/GB97/02836, a laniinated plastic material was produced comprising two layers [Fig. 7(a)]: a transparent base; and - a second layer consisting oftwo abutting parallel strips, one being a thin metallised strip and the other being a wide transparent strip.

A sheet of this material was aligned with a sheet of strong polythene [Fig. 7(b)], and these two sheets were sealed around all four edges to form a bag [Fig. 7(c)]. At the end of the interface between the two abutting parallel strips (ie. the end of the tearing line), a small nick was made. This bag can be opened easily without the need for scissors [Fig. 7(d)].

The tear along the polythene sheet in this type of bag is guided by the tearing line in the laminated material. As the bag is filled, however, the unsealed areas of the front and back of the bag are separated In order to ensure that the tearing line in the laminated material is sufficiently close to the polythene sheet so that it is still able to guide a straight tear, it is preferred to minimise this separation by sealing the sheets up to or close to the tearing line.

In a second, less preferred embodiment, the nick was made before the two sheets were sealed, but only in the transparent base. This can be opened, but the back of the bag, formed from the polythene sheet, is not torn. This kind of bag is not preferred.

In a third embodiment, shown in Figure 8, using the methods described in International Patent Application PCT/GB97/02836, a laminated plastic material was produced comprising three layers: - a transparent base; - a middle layer comprising two abutting parallel strips, one being a thin metallised strip and the other being a wide transparent strip; and - a transparent top layer over-printed with a coloured pattern.

Two sheets of this material were stacked together, ensuring that the interface between the metallised and transparent strips were aligned [Figure 8(a)]. Three edges of the materials were then heat-sealed, as shown in Figure 8(b). The bag was then filled with contents and the fourth edge was sealed [Figure 8(c)]. A nick was then made on one edge at the interface between the metallised and transparent strips. This nick can be used to initiate the opening of the bag by tearing to release its contents [Figure 8(d)].

In a fourth embodiment, rather than using two separate sheets, the bag was formed by folding one sheet into two, whilst still ensuring that the interface between the metallised and transparent strips are aligned.

In a fifth embodiment, shown in Figure 9, the sealing procedure for the fourth edge of the bag was altered. The sealed area was extended across the tearing lines, except for a small gap [Figure 9(c)]. When this bag is tom open, this small gap forms an opening [Figure 9(d)]. This opening allows the contents of the bag to be poured more easily, in the same way as a spout, and also makes a convenient opening for a straw [Figure 9(e)]. in a further embodiment, shown in Figure 10, a zip-lock was incorporated during manufacture to give a re-sealable bag.

It will be understood that the invention is described above by way of example only and modifications may be made whilst remaining within the scope and spirit of the invention.

ANNEX I LAMINATING APPARATUS This invention relates to apparatus and methods for producing laminated materials, for example such as are used in packaging.

Goods such as processed food, sweets, medication and liquids are often packaged in material which isolates them from water, gas, vapour, oil, chemicals and the like. This packaging material is usually decorated in order to distinguish the product from similar goods, for instance, or to provide directions for use, to list ingredients or to provide statutory information.

Typical material for this purpose is made from single or double layered transparent plastics over-printed with the desired design, with double layered materials offering better protection to goods.

In order to enhance the visual appeal of a package or to provide a degree of protection against counterfeiting it may also be desirable to add metallised effects, such as holograms, within such multi-layered material. The resulting laminated packaging material typically comprises a sheet of aluminium foil or holographic film sandwiched, and thus protected, between two sheets of transparent polyethylene or polypropylene, one or both of which could be over-printed with a design. This material is not transparent, however, due to the presence of the opaque metallised layer.

It would be desirable to have available a packaging material which includes a metallised layer but through which the contents of a package are visible. This could be achieved by sandwiching strips of metallised material, rather than whole sheets, between outer transparent layers. In the regions where the metallised layer is absent the material is thus transparent.

However, simply laminating strips of foil within two plastic layers is not feasible on a mass production basis. The final laminated material will not be of uniform thickness and this will be magnified when it is rolled up, for instance. It is therefore necessary for the middle layer to include strips of transparent material parallel and adjacent to the metallised material to provide a layer with as constant a thickness as possible.

A desirable laminated material would thus be of substantially uniform thickness, having five layers ie.: (A) a transparent film made from a material such as polypropylene or polyethylene, probably decorated with a design; (B) an adhesive layer; (C) a layer consisting of a combination of parallel strips of different materials in the same plane or surface. These strips might be, for instance, lightline aluminium metallised or partially-metallised laminating foil, metallised polypropylene film, aluminium foil, or transparent polypropylene or polyethylene; (D) a further adhesive layer; and (E) a heat-sealable or heat-melting film allowing easy application for an automatic packaging system.

Such laminated packaging materials would typically be manufactured according to the following process. The materials which make up layers (A) and (C) are loaded onto separate supply rollers. Material (A) proceeds from its supply roller through a glue tank, where an adhesive layer (B) is applied to its back surface, and then through a drying tunnel. The strips which form layer (C) issue from the relevant supply rollers and meet material (A) emerging from the drying tunnel (A) at an assembly roller. Layer (C) is bonded to adhesive layer (B) to form a laminated material (AC) which is collected on receiving roller.

To complete the packaging material, the laminate (AC) is removed from the receiving roller and re-loaded onto a supply roller. The process is repeated on material (AC), with adhesive being applied to layer (C) and heat-sealable film (E) being attached to form finshed product (ACE) laminate.

A significant problem when manufacturing laminated material in this way, however, is the alignment of the strips in layer (C). The strips, which might be of differing widths, will generally issue from separate supply rollers which might have drums of different diameters and different motor speeds. The different materials will tend to have different tensile strengths, different coefficients of friction, and different thicknesses.

During bonding at the assembly roller, aligning the strips in parallel on the same plane or surface without an overlap has so far not been possible. Avoiding wrinkles, creases, breakage, and deformation of strips during lamination is also difficult. These problems, of course, cause wastage of materials and interruption of the production line.

Furthermore, the alignment of the layers at the assembly roller is liable to change due, for instance, to vibration of the machine and for these reasons current machines and processes of manufacture are, in general, limited to just two strips.

There is thus a need for a laminating process in which the strips which make up layer (C) can be accurately aligned relative to layer (A), and in which the strips which make up layer (C) can be aligned without overlap.

According to the present invention there is provided an apparatus for producing laminated materials having a first supply roller, and a system comprising a second and a third supply roller, wherein the lateral positioning of said system can be adjusted in response to lateral movement of material which leaves the first supply roller, such that the lateral alignment of the second and third supply rollers remains constant with respect to said material.

The lateral positioning of said system may be adjusted manually during operation of the apparatus in order to maintain alignment of the second and third supply rollers with said material. Preferably, however, lateral movement of material which leaves said first supply roller is monitored by an electronic sensor which tracks a control line in the material. The output of the sensor can be used to adjust the position of said system automatically.

The control line can be any feature whose lateral movement can be tracked by an electronic sensor. The control line is preferably a visible coloured line but might be, for instance, a thin magnetic strip. Preferably such control lines have a width of 0.5mm to 3.0mm. Such control lines need not be continuous, but they must be electronically readable. Alternatively, the control line can be the edge of the material leaving the first supply roller.

The electronic sensor can be any sensor which is capable of accurately tracking the lateral movement of a control line.

Preferably the electronic sensor can track various types of control line. Suitable sensors are well known in the art for line and edge detection and these typically comprise a tungsten lamp and a CdS light detector which picks out very small changes in resistance as the control line meanders.

Depending on the reflection efficiency, different filters can be used with the detector. For instance, where reflection is efficient a ground glass filter might be used.

Preferably the electronic sensor is fixed to the system comprising the second and third supply rollers such that the system and sensor move in concert.

Preferably the lateral positions of the second and third supply rollers are independently adjustable within the system although during operation of the apparatus the lateral positions should remain fixed relative to each other.

According to a further aspect of the invention, there is provided a process for producing a laminated material comprising the steps of: (a) supplying material from a first supply roller; (b) supplying materials from a system comprising a plurality of further supply rollers; (c) tracking lateral movement the material leaving said first supply roller; and (d) adjusting the lateral position of said system in response to said lateral movement, such that the lateral alignment of the plurality of further supply rollers remains constant with respect to the material leaving the first supply roller.

Whilst adjustment step (d) may be effected manually, it is preferably effected automatically. For instance, the output of an electronic sensor which tracks lateral movement in material leaving the first supply roller may be used to control the lateral positioning of the plurality of supply rollers automatically.

Preferably, therefore, tracking step (c) involves tracking lateral movement in a control line in the material leaving said first supply roller by means of an electronic sensor.

The materials leaving said plurality of further supply rollers should all be of substantially the same thickness as each other. Preferably one or more of these materials is a holographic or metallic material.

The positions of the plurality of further supply rollers should be fixed relative to each other, such that their lateral positions remain constant with respect to each other. Preferably the plurality comprises 3 or more supply rollers.

According to a further aspect of the invention, there is provided a laminated material obtainable by a process as set out above.

Similarly, the invention also provides a laminated material comprising a layer made up of a plurality of parallel strips of material which abut and do not overlap.

Preferably the layer made up of abutting strips comprises at least three strips, one or more of which is a holographic or metallic strip. Preferably such a strip is bordered by transparent or translucent strips. More preferably, the layer comprises strips of transparent or translucent material alternating with opaque strips (eg. made from holographic or metallic material).

The layers will typically be joined to each other by adhesive. Accordingly, the invention provides laminated material having a transparent layer, an adhesive layer, and a layer comprising a plurality of parallel strips of material which abut and do not overlap. One of said strips is preferably a holographic or metallic strip. Of course, it will be appreciated that said "transparent" layer may be over-printed with a design, for instance, which renders it only partially transparent.

These laminated materials may also comprise further layers.

Preferably, therefore, the invention provides a laminated material as above, further comprising a fourth layer. This fourth layer may, for instance, be a heat-sealable layer or a layer of adhesive. The laminated material may also comprise a fifth layer, which may be made from the same material as the first layer, for instance, or may be a heat-sealable layer.

These laminated materials can be used for shrink-wrapping, for example, or during the manufacture of bags or pouches.

The invention also provides the use of a electronicallyreadable control line on material leaving a first supply roller to control the alignment of a plurality of further supply rollers with respect to said material.

A specific preferred embodiment of the invention will now be described by way of example with reference to the accompanying drawings in which Figure 1 illustrates the apparatus and Figure 2 shows the materials being laminated at the assembly roller (8).

The apparatus in Figure 1 is for bonding two layers (A) and (C) to form a laminated material. Layer (A) might, for example, be a transparent film made from polyethylene, over-printed with a design. Layer (C) is formed from a series of adjacent parallel strips (C1, C2, C3, ...) which abut and do not overlap. The strips might, for instance, be a wide transparent strip (C1) abutting with a thin metallised holographic strip (C2) abutting with a wide translucent strip (C3) Transparent film (A) is loaded onto supply roller (1) and its tension is adjusted. Similarly, the strips (C1, C2, C3, ...) which form layer (C) are loaded onto supply rollers (7) which are mounted in system (5). The tensions of the supply rollers (7) are adjusted and the rollers (7) are laterally arranged such that the edges of the strips leaving the rollers (7) which make up layer (C) will abut.

During operation film (A) proceeds through the glue tank (2), where adhesive layer (B) is applied to its back surface, and then into drying tunnel (3).

Film (A) with adhesive layer (B) emerges from the drying tunnel (3) and reaches a point where electronic sensor (4) is situated. In this preferred embodiment, film (A) contains a control line (X) which is still electronically readable through the dried adhesive layer (B). Electronic sensor (4) is intitially positioned so that control line (X) will be within its range of detection when film (A) passes beneath.

In the course of the laminating process, small lateral changes in the travel path of film (A) occur. The electronic sensor (4) detects these changes by tracking the position of the control line (X) in film (A) and transmits details of these changes to system (5) which comprises a supporting frame (6) on which a plurality of supply rollers (7) are mounted and secured. Each roller (7) is independently laterally adjustable vis-a-vis the other rollers (7) but during operation the rollers (7) are fixed relative to each other. Each roller (7) possesses its own speed reducer motor and tension detector.

In response to the signals from sensor (4), the lateral position of system (5) is adjusted. Rollers (7) thus move together relative to assembly roller (8) and the alignment of material (A) and the materials from rollers (7), which make up layer (C), remains constant.

As shown in Figure 2, the strips (C1, C2, C3, ...) forming layer (C) emerge from system (5) precisely aligned with film (A). At heated assembly roller (8) layer (A) meets the strips which form layer (C). The strips are bonded to adhesive layer (B) to form a laminated material (AC) which is collected on receiving roller (9).

To complete the packaging material, the laminate (AC) is removed from receiving roller (9) and re-loaded onto supply roller (1). After due adjustment of tension, the process is repeated on material (AC), with adhesive being applied to layer (C) and heat-sealable film (E) being attached to form finshed product (ACE) laminate.

The laminate (ACE) is left at an appropriate temperature for about 12 to 48 hours to let the layers settle before being used for packaging.

It will be understood that the invention is described above by way of example only and modifications may be made within the scope and spirit of the invention.

CLAIMS 1. An apparatus for producing laminated materials having a first supply roller, and a system comprising a second and a third supply roller, wherein the lateral positioning of said system can be adjusted in response to lateral movement of material which leaves the first supply roller, such that the lateral alignment of the second and third supply rollers remains constant with respect to said material.

2. An apparatus according to claim 1, further comprising an electronic sensor which tracks a control line in the material leaving said first supply roller.

3. An apparatus according to claim 2, wherein said control line is a visible coloured line.

4. An apparatus according to claim 2, wherein said control line is the edge of the material leaving said first supply roller.

5. An apparatus according to any one of claims 2 to 4, wherein said electronic sensor is fixed to said system such that the system and sensor move together.

6. An apparatus according to any one of claims 2 to 5, wherein the lateral positions of the second and third supply rollers are independently adjustable within said system.

7. A method for aligning materials leaving supply rollers in a machine by utilising apparatus according to any preceding claim.

8. A process for producing a laminated material comprising the steps of: (a) supplying material from a first supply roller; (b) supplying materials from a system comprising a plurality of further supply rollers; (c) tracking lateral movement of the material leaving said first supply roller; and (d) adjusting the lateral position of said system in response to said lateral movement, such that the lateral alignment of the plurality of further supply rollers remains constant with respect to the material leaving the first supply roller.

9. A process according to claim 8, wherein step (c) comprises tracking lateral movement in a control line in the material leaving said first supply roller by means of an electronic sensor.

10. A process according to claim 8 or claim 9, wherein the plurality of further supply rollers comprises 3 or more supply rollers.

11. A process according to any one of claims 8 to 10, wherein the materials leaving said plurality of further supply rollers are all of substantially the same thickness as each other.

12. A laminated material obtainable by a process according to any one of claims 8 to 11.

13. A laminated material comprising a layer made up of a plurality of parallel strips of material which abut and do not overlap.

14. A laminated material having a transparent layer, an adhesive layer, and a layer comprising a plurality of parallel strips of material which abut and do not overlap.

15. A laminated material according to any one of claims 12 to 14, wherein said plurality comprises at least three strips.

16. A laminated material according to any one of claims 12 to 15, further comprising a fourth layer.

17. A laminated material according to claim 16, wherein said fourth layer is a heat-sealable layer or a layer of adhesive.

18. A laminated material according to claim 16 or claim 17, further comprising a fifth layer.

19. A laminated material according to claim 18, wherein said fifth layer is a heat-sealable layer.

20. A laminated material according to any one of claims 12 to 19, wherein one or more of said strips is a holographic or metallic strip.

21. A bag made from laminated material according to any one of claims 12 to 20.

Claims

CLAIMS 1. A bag with a front and a back, with two abutting strips of material situated between the front and the back, the line of abutment constituting a tearing line.
2. A bag according to claim 1, comprising more than one layer of abutting strips between the front and the back.
3. A bag according to claim 2, wherein the lines of abutment in the layers of abutting strips are aligned.
4. A bag according to any preceding claim, wherein one end or both ends of the tearing line contains a nick.
5. A bag according to any preceding claim, sealed around its edges.
6. A bag according to claim 5, sealed up to or close to the tearing line.
7. A bag according to any preceding claim, wherein the two strips are made from different materials.
8. A bag according to any preceding claim, further comprising means for re-sealing an opened bag.
9. A bag substantially as hereinbefore described with reference to and as shown in the accompanying drawings.