GB2349862A

GB2349862A - Cold-seal wrapping of articles

Info

Publication number: GB2349862A
Application number: GB9911199A
Authority: GB
Inventors: Michael Mclaughlin
Original assignee: Dairy Crest Ltd
Current assignee: Dairy Crest Ltd
Priority date: 1999-05-13
Filing date: 1999-05-13
Publication date: 2000-11-15
Anticipated expiration: 2019-05-13
Also published as: GB2349862B; GB9911199D0

Abstract

Goods such as cheese are wrapped by a cold-sealing technique in material 22 comprising a flexible film having cold seal material on its inner face and at least one barrier film to ensure gas- and/or moisture-tightness. There may be a relatively soft cold seal layer and a relatively hard cold seal layer. The technique may be horizontal form-fill-seal with inert gas introduced into the wrapper-forming tube 23 at 24. A longitudinal fin seal may be produced by crimping rollers at 25, followed by transverse end sealing and cutting at 27. The wrapped articles may be rotated at 28R so that a line extending between the ends is inclined to the fore-and-aft direction, and pressure applied via rollers 31, 32 to enhance the cold seal of the inclined ends. The wrapping material may be a laminate with printing between layers thereof.

Description

2349862 WRAPPING OF ARTICLES This invention relates to the wrapping of

articles and is particularly, but not exclusively, concerned with the wrapping of items of food, for example blocks of cheese, in a fluid-tight manner. The word OfluidO is used herein to cover either or both of "gas" and filiquidll.

Whereas many items of food need to be wrapped in a liquid-tight manner, other articles such as blocks of cheese need to be wrapped in a gas-tight manner to preserve the cheese. Usually, during the cheese wrapping process, an atmosphere of a gas such as carbon dioxide is created around the article being wrapped so that, once the article is sealingly wrapped, it is is stored in that atmosphere. In the case of cheese, the carbon dioxide serves two functions:

firstly, it keeps at bay any oxygen which could cause premature degradation of the cheese; and secondly, it acts in conjunction with moisture in the cheese to create carbonic acid which has the effect of deterring mould growth.

Traditionally, blocks of cheese are wrapped in a film of flexible laminate material, drawn off from a reel. The film is drawn off horizontally and the blocks of cheese are located at spaced intervals, adjacent to the "inside,, face of the laminate and, with the cheese in an atmosphere of a suitable gas, opposing edge regions of the film are brought together, with the inside surface of one edge region facing the inside surface of the opposite edge region, so as to form a tube having a fin in the region of the abutting inside surfaces. Suitable heated crimping rollers are employed to urge the abutting inside surfaces together, so as to form a secure fin-shaped heat seal. At this stage the film resembles a tube, with the blocks of cheese in spaced relationship along the tube. The tube, carrying the blocks of cheese, is then passed to a crimping and cutting station, and this is where heated jaws which undergo a I'D motion" effect the crimping with cutting occurring at the same time over a reasonably long dwell period, the cutting taking place in the centre of the heat-sealed crimped region.

The product is a series of finished packs. As indicated, the sealing is effected by heat sealing and, for this purpose, the laminate will normally employ at least two layers. The "inside', layer, which may be formed of polyethylene, can serve as a moisture barrier and, upon heating, can form a suitable heat seal with an adjacent inside polyethylene surface. The "outside" of the heat sealable laminated film can serve as a gas barrier and may be formed from, for example, a polyamide (e.g. a nylon) or a polyethylene terephthalate (P.E.T).

other food items, such as cereals or crisps are filled by downward delivery into a chamber open at its upper end, which is subsequently sealed as one packet of food is severed from its neighbour, but the same general techniques are applicable.

There may be one or more further additional layers present between the "outside" layer and the "inside" layer. In spite of using the best heat sealing efforts, about 4% of the sealed blocks of cheese still leak, with the leakages being in the region of the seals. Currently, no significant problem has been experienced with the material from which the packaging is formed, as it forms a satisfactory gas and moisture barrier. It is the seals which are the problem.

In addition to the leakages experienced with such heat-sealed packages, the production of sealed packages using the heat-sealing technique is relatively slow and there are two additional disadvantages associated with the resulting product, namely that the packages are difficult to open and that, once opened, the packages are difficult to reseal, for example when some cheese has been removed for consumption and the remainder has been put back into the packaging material for further storage.

According to one aspect of the present invention, there is provided a method of wrapping an article in a fluid-tight manner, using as the wrapping material a film of cold seal-coated flexible material, wherein the film has cold seal materials on one face and also has at least one barrier film whereby the film is fluid tight, which method comprises:

advancing a length of the aforesaid film in the fore and aft direction of the production line; locating articles to be wrapped by the film at spa ced intervals adjacent the one face of the film, which one face is to become the inside surface as wrapping proceeds; curving the film around the located articles, so as to form a tube by bringing the inside surface of one edge region of the film into contact under pressure with the inside surface of the other edge region of the film, thus resulting in a cold seal in the form of a fin; and sealing by crimping under pressure, and cutting, the tube of film at intervals at positions between the articles so as to form wrapped articles having their crimped ends in the fore and aft direction.

If desired, additional steps may comprise:

rotating the wrapped articles so that a line extending between the crimped ends is inclined with respect of the fore and aft direction; and applying pressure via rolls to enhance the cold seal of the inclined crimped ends. This last-mentioned pressure-application step may become less effective if the film is too thick.

According to another aspect of the present invention, there is provided a method of wrapping an article in a fluid-tight manner, using as the wrapping material a film of cold seal-coated flexible material, wherein the film has cold seal materials on one face and also has at least one barrier film whereby the film is fluid-tight, which method comprises:

advancing a length of the aforesaid film in the fore and aft direction of the production line; curving the film around, so as to form a tube by bringing the inside surface of one edge region of the film int o contact under pressure with the inside surface of the other edge region of the film, thus resulting in a cold seal in the form of a fin; introducing articles to be wrapped within the tube; and sealing by crimping under pressure, and cutting, the tube of film at intervals at positions between the articles so as to form wrapped articles having their crimped ends in the fore and aft direction.

The packaging method can be conducted in an atmosphere of a selected gas, if desired.

According to a third aspect of the present invention, there is provided a method of wrapping an article in a fluid-tight manner, using as the wrapping material a film of cold seal-coated flexible material, wherein the film has cold seal materials on one face and also has at least one barrier film whereby the film is gas-tight and moisture-tight, which method comprises:

advancing a length of the aforesaid film in the fore and aft direction of the production line; locating articles to be wrapped by the film at spaced intervals adjacent the one face of the film, which one face is to become the inside surface as wrapping proceeds; -5 creating an atmosphere of a selected gas in the region of the thus located articles; curving the film around the located articles, so as to form a tube by bringing the inside surface of one edge region of the film into contact under pressure with the inside surface of the other edge region of the film, thus resulting in a cold seal in the form of a fin; and sealing by crimping under pressure, and cutting, the tube of film at intervals at positions between the articles so as to form wrapped articles having their crimped ends in the fore and aft direction.

If desired, the packaging may include the following additional steps:

rotating the wrapped articles so that a line extending between the crimped ends is inclined with respect of the fore and aft direction; and applying pressure via rolls to enhance the cold seal of the inclined crimped ends.

Conveniently the pressure required to create the fin seal is applied by a pair of pressure rolls, or by two pairs of pressure rolls, to create the fin seal which extends along the fore and aft line. At the next station, the action of the crimping and cutting equipment forms transverse seals such that, where the resulting wrapped article is rotated through 90', the next pressure rolls apply pressure in a line inclined, generally perpendicularly, to that along which the transverse seals were formed.

An important feature of the present invention is the use of a wrapping material which has a coating of a cold seal nature such that, when regions having their cold seal faces opposing each other are forced together, an effective cold seal is created.

Preferably, but not necessarily, the cold seal material takes the form of two different materials in two adjacent layers. Cold seal materials can be regarded as hard, medium and soft, with the hard material being the least tacky material at a given temperature. Preferably, therefore, the wrapping material employed in the present invention has as the exposed surface on the inside surface of the material a layer of soft cold seal, as this is the cold seal material which bonds most readily to another layer of cold seal material. when different regions of the same film are brought together during the sealing operation.

The layer of soft -cold seal is preferably disposed on a layer of hard cold seal which, in turn, is supported on suitable underlying layer which can be thought of as base or substrate and which can provide the gas and/or moisture barrier, such a base being formed of a single layer or multiple layers. The base could be an aluminium foil. The layer of hard cold seal material can serve two useful purposes, namely: firstly, it can act as a "key" between the exposed soft cold seal layer and the underlying base or substrate; and, secondly, it can provide a sufficient dimension of sealant to take up variations in thickness in the wrapping material.

The main base can be a metallic foil, like the aforementioned aluminium foil, or it might be an organic layer, such as a layer of polypropylene.

other layers may also be present in the wrapping material to achieve the desired characteristics for that material. For example, there may be present the following five layers in the following order, starting from the soft cold seal material layer:

(i) a layer of latex/sticky rubber soft cold seal material (at a coating density of 4g/m2); (ii) a layer of latex/sticky rubber hard cold seal material (at a coating density of 4g/M2); (iii) a polyvinylidene dichloride layer (at a coating density of 2-3g/m2); (iv) a polypropylene base (having a thickness of 26 microns); and M an acrylic layer which can serve as a barrier.

Where it is desired that the product displays written material, suitable printing can be provided between appropriate layers of the laminate wrapping material.

Whilst it is often preferred to employ both a soft cold seal layer(e.g. at a density of 4 9/M2) and a hard cold seal layer (e.g. at-a density of 4 g/m 2), it is possible to employ a single layer of cold seal material (e.g. at a density of 8 g/m 2).

if desired, in order to assist in the drawing off of the film of material from the starting reel, the laminate wrapping material can be provided with a release lacquer on that face remote from the cold seal layer(s).

It can be appreciated that in the method of the present invention there are up to three stages at which a cold seal is formed or enhanced, namely (i) during the creation of the fin seal, (ii) during the combined crimping and cutting to form the transverse end seals, and (iii) when the wrapped articles have been rotated and the former transverse seals which are now projecting laterally are subjected to a second sealing operation to enhance the effectiveness of those seals.

It is certainly convenient for each of the first and third of these three sealing exercises to be carried out by one pair or more than one pair of pressure rollers. When forming cold seals by the application of pressure rollers, the nature of the seal is enhanced if the rollers, instead of having plain cylindrical surfaces, have proud regions with the proud regions on one roller in a pair of rollers being opposed to the proud regions in the other roller in the same pair of rollers. By this technique enhanced lines of sealing are created, in positions corresponding to the nip between the proud regions of the rollers.

With regard to the second pressure sealing stage, which is combined with the cutting stage, whilst suitable rollers can be provided, nonetheless it can be more convenient for that stage to be effected by two opposing jaws which move together to cold seal and cut the adjacent regions of wrapping material. Such jaws can undergo D motion, thus enabling them to stay in contact with the travelling "tube" of material for a short time before being withdrawn and brought back to their upstream starting position.

Again, as with the pressure rollers, the jaws can is have proud regions with the proud regions on one jaw being opposed to proud regions on the opposing jaw.

The use of D motion jaws can be used to provide an easy open/easy close seal for certain types of articles, for example confectionery, where a high quality seal is not vital, as the pressure in the nip between D motion jaws is not so high as can be achieved by rotating jaws.

If desired, the pressure rolls used in the first pressure sealing stage to create the fin seal can be provided with circumferential proud regions with the result that in the fin seal there are enhanced lines of sealing extending in a direction parallel to the main fore and aft direction of operation. Then, with regard to the second cold sealing stage, the jaws can have proud regions extending in the main fore and aft direction so that the transverse seals, as well as the fin seal, have lines of enhanced sealing parallel to the main fore and aft direction in terms of the production line. If, in accordance with one of the methods of the present invention, the wrapped article is then rotated, conveniently through 9C, so that the transverse seals which were originally in the fore and aft direction are now projecting laterally, then it may be preferred for the pressure rollers in the third cold-seal pressure stage to have cylindrical proud regions so that the lines of enhanced sealing created by the third stage of application of pressure are inclined, preferably at 900, to the lines of sealing created during the first and second pressure application stages, with the result that the crimped regions have a "mesh" of lines of enhanced sealing, thereby providing an effective seal.

Whilst the arrangement indicated above is particularly easy to implement, nonetheless good results can also be obtained when the proud regions on is the rollers or jaws in the different pressure-applying stages are at right angles to those mentioned above.

This would mean that in the first and third pressure stages the rollers of the pressure rolls have proud regions which extend parallel to the axis of rotation of the rollers and it would also mean that the proud regions in the jaws employed to effect the second pressure-application and cutting stage are transverse to the main fore and aft line of direction.

The film can be generally horizontal whilst discrete articles for wrapping are positioned beside the film. Where articles such as cereals or crisps are to be wrapped, the film and tube can, more conveniently, be vertically disposed.

As a result of employing the above mentioned sealing techniques, particularly satisfactory seals are formed. In fact, the failure rate can be caused to fall considerably from the 4% associated with heat sealed packages, to an almost non-existent level. Not only that, but also the sealed packages can be opened more readily and can, after part of the cheese or other article has been removed, be reclosed to provide a reasonable degree of sealing (depending on the pressure applied by the person undertaking the re-sealing).

Moreover, it has been found that, whereas blocks of cheese can be wrapped using the heat-sealing technique at a rate of about 90 packs per minute on a single production line, it is possible using the cold sealing technique in accordance with the present invention to increase the rate to at least 300 packs per minute.

Furthermore, the wrapping material used to undertake the cold sealing in accordance with the present invention is less expensive than the wrapping material employed in the conventional heat sealing arrangement.

is A yet further aspect of the present invention provides an article wrapped by a cold-sealing technique in wrapping material, the wrapping material being a film of cold seal-coated flexible material having cold seal materials on its inner face and also being provided with at least one barrier film to ensure that the film is gas-tight and/or moisture-tight.

Preferably the wrapped article in accordance with this further aspect of the present invention is wrapped in wrapping material which has a relatively soft cold seal layer as well as a relatively hard cold seal layer. In addition, the wrapped article in accordance with the second-mentioned aspect of the present invention preferably has, in the region of the sealed zones, suitable lines of enhanced sealing with some lines being inclined to other lines so as to form a more effective seal.

For a better understanding of the present invention and to show how the same may be carried into effect, reference will now be made, by way of example, to the accompanying drawings, in which:

Figure I is a side-view of wrapping apparatus in accordance with the prior art;

Figure 2 is a section, on an enlarged scale, of the film used on the apparatus of Figure 1; Figure 3 is a view from above of the wrapped article produced on the apparatus of Figure 1; Figure 4 is a perspective view of the wrapped article prior to final crimping; Figure 5 is a side view of an apparatus for conducting one aspect of the packaging method in accordance with the present invention; Figure 6 is a view from above of the arrangement shown in Figure 5; and Figure 7 is a section, on an enlarged scale, of the film used on the apparatus in Figure S.

Referring first to the arrangement shown in Figures I to 4, there is a reel 1 from which is drawn off a film of flexible laminate 2 which is folded so as to form a tube 3, with gas being introduced at point 4 into the tube 3. Positioned on the film 2 prior to the folding of the film into the tube 3 are spaced-apart articles, such as blocks of cheese, but these are not shown (for the sake of clarity).

The opposing edge regions of the tube 3 are passed between pairs of crimping rollers to form a fin seal 6 at the rear, and the resulting product is then subjected to the action of the heated jaws 7 which undergo D motion so as to form transverse seals and effect cutting of the tube into lengths, thus resulting in the finished pack 6 which has end seals 9 and 10.

Figure 2 shows the film 2 which has a polyamide or polyethylene terephthalate barrier layer 11, a laminating layer 12 and a polyethylene heat-sealing layer 13.

The finished pack 8 shown in Figure I is shown in more detail in Figure 3, and a perspective view of the pack 8, shortly before the final sealing has taken place, is shown in the Figure 4.

Referring now to the arrangement shown in Figures to 7, which is in accordance with one aspect of the present invention, there is a reel of cold seal-coated flexible film 22 which is drawn off and formed into a tube 23 by the bringing together of the inside edge regions of the film. Where desired, a suitable gas is introduced at the point 24 to create the appropriate atmosphere within the tube, and also, as with Figure 1, articles are introduced into the tube at spaced intervals. The articles are not shown in Figure 5 but are shown as Articles A in Figure 6.

With the film 22 folded around the articles, a fin seal 26 is formed as a result of the action of the crimp rollers 25, and simple rotary crimp jaws 27 provide transfer seals and also effect the cutting of the tube into discrete lengths so as to provide discrete packages 28 which have end seals 29 and 30.

It desired, and as shown, the packages 28 can be rotated (see 28R) and the rotated package sent through two further rolls 31 and 32 which recrimp the end seals, to provide the resulting finished pack 33. The additional rollers 31 and 32 provide what can be thought of as a secondary seal for what were the original end seals 29 and 30, but this is optional depending on the quality of seal required and on the thickness of the film.

In Figure 7 there is shown, on an enlarged scale, the film 22 which has a cold seal layer 41, a barrier film 42 and a release lacquer 43 (to prevent blocking).

It will be appreciated that considerable variations in the nature of the film can be employed depending on the quality of the seal required and on the thickness of the seal, as well as other criteria.

-13

Claims

CLAINg

1. A method of wrapping an article in a fluid tight manner, using as the wrapping material a film of cold seal-coated flexible material, wherein the film has cold seal materials on one face and also has at least one barrier film whereby the film is fluid-tight, which method comprises:

advancing a length of the aforesaid film in the fore and aft direction of the production line; locating articles to be wrapped by the film at spaced intervals adjacent the one face of the film, which one face is to become the inside surface as wrapping proceeds; curving the film around the located articles, so is as to form a tube by bringing the inside surface of one edge region of the film into contact under pressure with the inside surface of the other edge region of the film, thus resulting in a cold seal in the form of a fin; and sealing by crimping under pressure, and cutting, the tube of film at intervals at positions between the articles so as to form wrapped articles having their crimped ends in the fore and aft direction.

2. A method according to Claim 1, which additionally includes:

3. A method of wrapping an article in a fluid tight manner, using as the wrapping material a film of cold seal-coated flexible material, wherein the film has cold seal materials on one face and also has at least one barrier film whereby the film is fluid-tight, which method comprises:

advancing a length of the aforesaid film in the fore and aft direction of the production line; curving the film around, so as to form a tube by bringing the inside surface of one edge region of the film into contact under pressure with the inside surface of the other edge region of the film, thus resulting in a cold seal in the form of a fin; introducing articles to be wrapped within the tube; and sealing by crimping under pressure, and cutting, the tube of film at intervals at positions between the articles so as to form wrapped articles having their crimped ends in the fore and aft direction.

4. A method according to Claim 3, which is is conducted in an atmosphere of a selected gas.

5. A method of wrapping an article in a fluid tight manner, using as the wrapping material a film of cold seal-coated flexible material, wherein the film has cold seal materials on one face and also has at least one barrier film whereby the film is gas-tight and moisture-tight, which method comprises:

advancing a length of the aforesaid film in the fore and aft direction of the production line; locating articles to be wrapped by the film at spaced intervals adjacent the one face of the film, which one face is to become the inside surface as wrapping proceeds; creating an atmosphere of a selected gas in the region of the thus located articles; curving the film around the located articles, so as to form a tube by bringing the inside surface of one edge region of the film into contact under pressure with the inside surface of the other edge region of the film, thus resulting in a cold seal in the form of a fin; and sealing by crimping under pressure, and cutting, the tube of film at intervals at positions between the articles so as to form wrapped articles having their crimped ends in the fore and aft direction.

6. A method according to Claim 5, which additionally includes:

7. A method according to any preceding claim, wherein the pressure required to create the fin seal is applied by a pair of pressure rolls, or by two pairs of pressure rolls, to create the fin seal which extends is along the fore and aft line.

S. A method according to Claim 2 or 6, wherein, where the resulting wrapped article is rotated through 900, the next pressure rolls apply pressure in a line inclined, generally perpendicularly, to that along which the transverse seals were formed.

9. A method according to any preceding claim, wherein the cold seal material takes the form of two different materials in two adjacent layers.

10. A method according to any preceding claim, wherein the wrapping material has as the exposed surface on the inside surface of the material a layer of soft cold seal.

ii. A method according to Claim 10, wherein the layer of soft cold seal is disposed on a layer of a hard cold seal material which, in turn, is supported on an underlying layer which serves as a base or substrate and which provides the gas and/or moisture barrier.

12. A method according to Claim 11, wherein the base is a metallic foil or an organic layer.

13. A method according to any preceding claim wherein the wrapping material is a laminate, and 16- wherein printing is provided between layers of the laminate.

14. A method according to any preceding claim, wherein the cold seals are formed by the application of pressure from one pair or more than one pair of pressure rollers.

15. A method according to Claim 14, wherein the rollers have proud regions with the proud regions on one roller in a pair of rollers being opposed to the proud regions in the other roller in the same pair of rollers.

16. An article wrapped by a cold-sealing technique in wrapping material, the wrapping material being a film of cold seal-coated flexible material having cold seal materials on its inner face and also being provided with at least one barrier film to ensure that the film is gas-tight and/or moisture-tight.

17. An article according to Claim 16, which is wrapped in wrapping material which has a relatively soft cold seal layer as well as a relatively hard cold seal layer.

18. A method according to Claim 1, substantially as hereinbefore described with reference to Figures 5 to 7 of the accompanying drawings.