WO2000021852A1

WO2000021852A1 - Packaging wrapper

Info

Publication number: WO2000021852A1
Application number: PCT/EP1999/007795
Authority: WO
Inventors: Eddy Daelmans; Rémi Cottenceau; Claude Martinet
Original assignee: Transpac N.V.; Sig Pack Sapal S.A.
Priority date: 1998-10-15
Filing date: 1999-10-05
Publication date: 2000-04-20
Also published as: AU6472699A; HUP0103966A3; MA25591A1; DZ2907A1; EA200100270A1; AR020820A1; KR20010082215A; DE69905598D1; DE69905598T2; BG64000B1; SK5072001A3; PT1121301E; EA002578B1; DK1121301T3; GEP20033086B; EE04364B1; MY130730A; JP2002527306A; EP0994039A1; CN1321133A

Abstract

The invention concerns a wrapper consisting of a foil capable of being cut up into separate films (20, 52, 56, 62) for packaging an article (34) and comprising, on the inner side relative to the article to be packaged (12), in particular a food product, said films designed to be closed by being folded around said article (34). In order to facilitate the choice of foil material without having to consider its fold-retaining properties, the foil comprises, on each film, at least a cold seal coating strip with controlled adherence, ensuring that the folds are maintained and the package is closed, following the phases which consist in folding the film around the article to be packaged.

Description

PACKAGING ENVELOPE

The present invention relates to a packaging envelope suitable for use with an article to be packaged and consisting of a sectionable film in separate films intended to be closed by folding around the article to be packaged.

Without being limited thereto, the invention relates more particularly to the field of packaging of confectionery and chocolate or other consumer products such as, for example, bouillon cubes. Generally, the articles are individually wrapped in a rectangular film of preprinted film of an appropriate size and shape, which individually wrapped articles can in turn be packaged in bulk in a packaging bag of an appropriate size. . The article to be packaged, for example in the shape of a parallelepiped, is, according to a common method of packaging, placed in the center of the back, that is to say on the unprinted side of a rectangular film. The two longitudinal sides are raised (or flap depending on the orientation of the article and the type of packaging machine) vertically against the longitudinal faces of the article. Then, the side panels are raised vertically against the two transverse faces of the article and their upper edges are folded flat on the upper base of the article, these last two operations necessarily being carried out by successive and oblique folds with the longitudinal panels previously noted. The packaging ends with the folding of the upper edges (which have since become trapezoidal tabs) of the longitudinal sections, one on the other, on the upper base of the article.

It should however be noted that, depending on the shape of the product to be packaged and the nature of the packaging machine, other sequences of folding of the packaging film are possible, these folding sequences being carried out according to a configuration of well defined fold lines. This configuration of fold lines of the packaging film always remains the same for the same article to be packaged by the same packaging method.

An important problem which arises at this level is that of the retention of the folds at the end of the packaging operation so that the packaging remains closed. This retention can only be ensured at the cost of a selection tion of the film used as a substrate, which must have appropriate mechanical characteristics such as pliability and, in particular, a pronounced tendency not to return to its initial position after the film has been folded during packaging. This problem manifests itself, in particular, when packaging small items such as confectionery products, such as candies, pralines, lollipops, barley sugars, chocolate bars, etc. or bouillon cubes.

As a solution, it is known to select particular substrates known for their high foldability, such as waxed paper, cellophane, aluminum laminates, or even synthetic films containing an appropriate amount of an additive which increases the foldability. of this substrate.

This solution however considerably limits the possibilities of choosing films used as packaging substrates or considerably increases the cost thereof.

Also known are packaging films of certain articles such as broth cubes, where the packaging is closed by gluing. For this purpose, the films comprise, on the front side, that is to say on the outside side of the article to be packaged, a structure of hot sealing plaster whose configuration is adapted to the configuration of the folds produced during of the packaging.

This packaging process has the disadvantage that the packaging machine must be specially adapted to this process since it requires a heat source. In addition, if this heat source consists of heating plates, bonding can only be carried out on perfectly flat surfaces of the article to be packaged and requires, in addition to the time necessary for carrying out the sealing, a relatively pressure important that a number of products do not support.

Another disadvantage is that this packaging method is totally unsuitable for packaging heat-sensitive articles, in particular chocolate products, and does not allow the selection of a packaging substrate having a low resistance to temperatures. Patent application EP-0 870 695 proposes a packaging film intended to be closed by folding around the article, the front side, that is to say the face which is outside the article, comprises a structure of cold sealing plaster arranged in a configuration such that these areas of sealing plaster overlap by folding the film around the article. These sealing plaster zones therefore ensure retention of the folds when the film material has the particularity of not keeping the folds. This film, however, includes a fusible varnish which keeps the film closed and which has the drawbacks mentioned above. The film also has the disadvantage that the back side must have non-stick strips to be able to unwind the film from a roll.

The object of the present invention is to provide a new packaging which makes it possible to considerably widen the choice of film used and which allows packaging of the film in rolls.

To achieve this objective, the present invention provides a packaging envelope arranged for packaging an article, in particular a food product, this envelope consisting of a film conditioned in the form of a roll and sectionable transversely into separate films, intended to be closed. by folding around the article, characterized in that the film comprises, on each film, at least along a transverse edge of the film, a strip of cold sealing plaster, which ensures controlled adhesion of the film on itself and which is powerful enough to keep the packaging closed, but which is insufficient to disturb the unwinding of the film from its roll. The film preferably comprises, on each film, along each transverse edge thereof, a strip of cold sealing plaster, one of the strips being on the front side and the other on the side. back of the film.

The Applicant has made the surprising discovery that the prior coating, at least partially, of the film used as packaging envelope with a well-determined cold sealing coating, makes it possible to obtain, after closing the packaging film by folding , folds with excellent retention and also allows packaging of the film in rolls. The point is that the substance used as the sealer has little or no adhesion to a smooth surface or surface treated for this purpose but, on the other hand, has good adhesion when applied to itself, which is the case during folding. The retention of the folds is therefore ensured simply by light pressure and by mutual overlapping of certain areas of sealing plaster and this without other accessories than those necessary for folding the packaging.

By cold sealing, according to the present invention, is meant a sealing which is carried out instantaneously, by simple contact, at a temperature of between 0 and 50 ° C. approximately. In reality, the temperature is not a critical parameter with regard to obtaining a seal by means of a cold sealing coating and has practically no influence on the quality of the seal obtained. Sealing is therefore carried out without the need for additional heat, at ambient temperature of the space in which the packaging unit is located. In fact, cold sealing coatings have, until now, been mainly used in layers on a substrate undergoing little or no deformation. We can expect, in fact, significant blocking problems due to the self-adhesive properties of the cold sealing coating throughout the use of this cold sealing coating on a non-planar substrate.

The present invention therefore allows the use of cheaper films and having better properties (rigidity, printability, aesthetic quality) for packaging articles without restriction as to the shape of said articles. As for the use of rigid films, it will be noted that, until now, the use of rigid films has always been avoided for the packages to be closed by folding. These rigid films have, in fact, a very low ability to retain the fold.

When preparing a roll of film for a packaging, one side of which is coated with sealing plaster, a non-stick coating may be applied to the other side in order to avoid contact adhesion between the coated side. sealant and the other side during winding. It should however be noted that there are so-called “dry” cold sealing coatings which, when used in conjunction with certain substrates such as polypropylene films, do not require such an anti-coating. adhesive. These two methods can also be used in the context of the present invention.

According to an advantageous embodiment, the structure of the sealing plaster zones comprises two strip structures arranged in a W shape, along the two opposite sides of the film, a strip along a third side of the film. and between the two W-shaped structures and two areas in the two corners of the fourth side of the film.

The sealing plaster strips arranged according to the folding configuration can have a width of the order of 4 mm.

The configuration of the sealing plaster strip structure can have various shapes depending on the article to be packaged and on the folding sequences.

In addition to the strip structure along the folds to be produced, each film may include a strip of sealing plaster along an edge of a third side. This strip will be on the tongue which, at the end of the packaging process, will be folded down first on the base of the article to be packaged and will ensure adhesion with the tongue which will be folded down last. Each film of packaging film may further include additional areas of sealant allowing adhesion of the tab which is lastly folded down on the base of the packaged article and thereby contribute to maintaining the packaging closed.

According to another embodiment, one can provide, along the edge of one of the tabs which are folded down lastly at the end of the packaging operation, a strip of cold sealing plaster of the type says "soft". This type of plaster, unlike the dry plaster mentioned above, allows adhesion on the smooth side of the back of the packaging film. This strip of soft sealing plaster ensures good adhesion between the two longitudinal tabs folded down at the end of the packaging operation and thus allows the production of a hermetically sealed packaging which improves the conservation of the article wrapped in reducing the influence of factors such as humidity, odor, dust or others on the article. This adhesion between the “soft” type coating and the smooth surface of the back of the film must not however be irreversible because it must allow an unwinding of the film when it is conditioned and stored in a roll without the risk of breaking the film. In other words, it is necessary to choose the sealing coating of the "soft" type according to the nature of the substrate on which it is applied so that, on the one hand, its adhesion on the back of the substrate is sufficiently weak to allow the packaging film to be unwound from a roll and, on the other hand, to be powerful enough to ensure an almost hermetic closure of the packaging. We can therefore speak of a controlled adhesion. This controlled adhesion has, in addition, the advantage of being able to open the packaging and to close it several times without appreciable reduction in the qualities of adhesion.

As indicated above, one of the advantages of the present invention is that it allows the use of wide ranges of possibilities as regards the nature of the substrate used. Examples of suitable substrates are plastic films of about 10 to 100 microns made of extruded and oriented polypropylene, polypropylene as a cast film, polyester, polyethylene, extruded and oriented polyamide, or polyamide as a cast film .

In accordance with the present invention, it is also possible to use a paper substrate (rubbed or coated). In general, any support material or flexible packaging material may be suitable as a substrate according to the present invention. These different substrates can consist of a single layer, a single metallized layer or in several laminated and / or coextruded layers.

The choice of cold sealing coating is not critical. As a "soft" type cold sealing coating, pressure sensitive adhesives can be considered which are substances which are permanently sticky and which spontaneously adhere to the surface of most materials under pressure. effect of a simple moderate pressure. As a general rule, pressure-sensitive adhesives are compositions based on natural and / or synthetic rubber associated with modified cellophanes, phenol-formaldehyde resins or hydrocarbon resins (waxes). Besides rubbers, polymers based on styrene, (metha) crylic acid or vinyl ether are widely used, alone or as a mixture, also in combination with resins. Finally, it is also possible to use silicone resins. We use preferably compositions comprising mixtures of natural and synthetic rubber and copolymers of (metha) crylic acid and styrene.

In accordance with the present invention, the cold sealing coatings are placed on the substrates at a rate of approximately 1 to 5 g / m ² .

Cold seal coatings can be applied as a solution, dispersion or even in the molten state.

Other particularities and characteristics of the invention will emerge from the detailed description of some embodiments presented below, by way of illustration, with reference to the appended drawings in which:

- Figure 1 shows the front side of a first embodiment of a packaging film according to the present invention;

- Figures 2 to 8 illustrate successive sequences of an example of packaging a candy with the film of Figure 1;

- Figure 9 shows the front side of a second embodiment of a packaging film according to the present invention;

- Figure 10 shows the front side of a third embodiment of a packaging film according to the present invention; FIG. 11 mounts a section, on an enlarged scale, through an example of an embodiment according to FIG. 10 and

FIG. 12 represents a simplified variant of the embodiment of FIG. 10.

Figure 1 shows the front side, or printed side, of a packaging film 20 after it has been cut from a film unwound from a storage roll (not shown) in the direction shown by the arrow A in the figure.

The cold sealing coating is arranged in a structure 22 which is adapted to the configuration of the fold lines produced during packaging and an example of which will be described later, in the case of FIG. 1, there are two strip structures 24, 26 with a width of the order of ± 4 mm, approximately W-shaped, along two opposite sides of the film 20 and a strip 28 along a third side of the film between the two lateral W-shaped structures. On the opposite side from that of the strip 28 there are also, in the corner regions, two zones 30 and 32 of cold sealing plaster. Related to initial film stored on a roll, the strips 24, 26 lie along the longitudinal edges while the strip 28 is transverse. On the roll, these different strips of adhesive plaster on the front side are on the outside of the different turns of the roll. The film 20 of FIG. 1 can be prepared by depositing, on the front side of an oriented polypropylene film 25 microns thick, metallic or not, a thin printing or primer layer (for example, product 10-612205 -4 MX41 from SIEGWERCK) intended to improve the adhesion of the printing ink. The film is then printed by techniques known per se, such as, for example, heliographic or flexographic printing or even offset printing. On the print, a protective lacquer known per se is then deposited. On this lacquer, the structures 22 of cold sealing plaster are deposited according to the model shown in FIG. 1. This deposition can also be carried out by printing techniques known per se.

As a cold sealing coating, the product IP7905 or IP7936 from the company SWALE can be used, which will be deposited at the rate, for example, of 3 g / m ² . This is an adhesive coating which adheres only to itself. In other words, this coating does not adhere to the untreated smooth side on the back side of the film, which allows the film to be easily stored and packaged in the form of a roll without any unwinding problem. This sealing coating has, moreover, the quality of having a low coefficient of friction (COF = coefficient of friction) on metal which is of the order of 0.2 to 06, while the COF on metal is normally in the range of 1-1, 5. This low coefficient of friction reduces the risk of jamming and adhesions on the folding box.

We will now describe, with reference to FIGS. 2 to 8, an operation of packaging a candy of substantially parallelepiped shape with the film 20 of FIG. 1. This is placed on the candy with the back or face untreated facing the candy so that the strip 28 and the opposite side with adhesive zones 30 and 32 lie in the longitudinal direction of the candy and the W-shaped structures in the transverse direction of the candy. The sides of the film 20 are then folded over the longitudinal faces of the candy as shown in FIG. 2. The next operation consists in folding down the central region on each side of the film with the structures 24 and 26 on the lateral faces of the candy 34 as shown in FIG. 3. This operation is carried out by folding with the longitudinal sides of the film 20 along oblique fold lines 36 and 38. As can be seen in FIG. 3, the two W-shaped structures 24 and 26 (26 not visible in FIG. 3) of the sealing plaster are arranged so as to that the two outer members of the W-shaped structures run along the fold lines 36, 38 and that the V-shaped inner part is applied to the transverse side of the candy 34.

The next operation consists in folding down, on each side of the candy 34, the two sides delimited by the fold lines 36 and 38 inwards in the direction of the arrows 1 and 2 in FIG. 3. This operation places the outer bands of the W-shaped sealer structures, that is, those along the fold lines 36 and 38, on the V-shaped interior strips and results in the configuration according to Figure 4. These folding sequences are obviously the same on the two lateral sides of the candy. Since all the strips of the two W-shaped structures 24 and 26 overlap completely and the cold sealing plaster used adheres perfectly to itself, the configuration of FIG. 4 is a stable configuration with perfect retention folds made so far.

The next folding sequence is shown in Figure 5 and consists in folding down the lower parts of the previously folded and folded side panels, on the underside of the candy 34. This operation is carried out by folding with the longitudinal sides along lines of oblique folds 40, 42, 44, 46 which transform the longitudinal sides into trapezoidal tabs 48, 50. The result of this folding sequence is clearly visible in FIG. 6 which represents a view from below and of the hidden side on the previous figures.

Here also, it should be noted that the two zones 30 and 32 of cold sealing plaster are arranged so that their internal oblique edges (see also FIG. 1) run along the fold lines 40 and 42 of the tab 48 as can be seen in Figure 6. Figures 7 and 8 illustrate the last stages of the packaging.

First, the tongue 50, provided with the strip of sealing plaster 28, is folded back on the inner face as shown in FIG. 7. The second tongue 48 is then folded back on the tongue 50 to form the configuration of FIG. 8.

When the tongue 48 is folded down, the two zones 30 and 32 of sealing plaster are, in part, superimposed on themselves and, in part, applied to the adhesive strip 28 of the tongue 50. Consequently, given that the tongue 48 adheres to itself and to the tongue 50, the configuration of FIG. 8 is a stable configuration with good retention of all the folds. However, it should be noted that when the tongue is folded down

48 on the tongue 50, the adhesive tape 28 ^adheres' by its ends to the adhesive areas 30 and 32. However, the central portion will contact the tab of the back face 48 to which it will not adhere. In other words, if the film of FIG. 1 ensures a packaging with stable and permanent closure, it will not ensure a tight closure.

All the packaging sequences described below are carried out automatically in a packaging machine. In this context, it is important to note that the proposed packaging films are suitable for existing packaging machines without any need for modification or adaptation. It should however be noted that the packaging described below is only an example of a folding configuration of a given machine. Other machines can fold according to different fold line configurations. In this case, the model of the adhesive structures shown in FIG. 1 should be adapted to the configuration of the fold lines produced by the folding machine, the opposite being more difficult.

We will now describe, with reference to FIG. 9, a second embodiment of a packaging film according to the present invention and represented overall by the reference 52.

A film is prepared and printed, for example in oriented propylene on which a structure 22 of cold sealing plaster is deposited as in the case of FIG. 1. A strip 54 is then deposited only on the adhesive strip 28 “soft” type cold sealing plaster. For this purpose, one can use the product 22-392 or the product 22- 263 of the company CRODA deposited at a rate of 3 g / m ² . The adhesive of the strip 28 acts as a "primer" for the "soft" adhesive of the strip 54.

The “soft” type adhesive of the strip 54 has the property of adhering, not only to itself, but also to the smooth untreated surface on the back side of the film 52. The result is that when the film 52 is used for a packaging operation according to FIGS. 2 to 8, at the end of the packaging, when the tongue 48 is folded over the tongue 50 (see FIGS. 7 and 8) and on its adhesive strip 54, the side reverse side of the tongue will adhere to the adhesive strip 54 of the tongue 50. This produces a packaging which not only has good fold retention capacity, but which is also waterproof and almost hermetic.

According to another aspect of the invention, the type of sealing coating of the “soft” type is chosen so as to have a controlled adhesion, more precisely, so that this adhesion is sufficient to ensure a tight closure of the packaging but insufficient for adhesion to be irreversible. In other words, the adhesive strip 54 must be able to be peeled off without difficulty from the smooth surface of the film 52. This allows the film roll to be stored without risk of breaking during unwinding. FIG. 10 represents a third advantageous embodiment of a packaging film according to the present invention and generally designated by the reference 56.

It is again possible to use an oriented polypropylene film which is appropriately printed, possibly after having deposited a "primer". A non-stick coating 60 is then deposited over the entire recto surface. Suitable non-stick products consist of mixtures of polyamide resin and polyethylene wax (for example products 10-609345-3P from the company SIEGWERCK and 994404- X from the company SICPA) deposited at a rate of 1.5 g / m ² . Patterns 22 of cold sealing plaster identical to those of FIG. 1 are then applied to this coating. On the back side, then, approximately applied between zones 30 and 32 on the front side and, as shown, in dashed lines at 58, a strip of dry type cold tack coating. When the film 56 is used for packaging as described with reference to FIGS. 2 to 8, the adhesive strip 58 will be found, at the end of the packaging operation (see FIG. 7), on the inside of the tab. 48 and, when folded down of it, it will adhere to the adhesive strip 28 of the tongue 50 to form an almost hermetic package.

When the film according to FIG. 10 is stored in the form of a roll, the adhesive strips 58 on the back are generally in contact with the non-stick coating 60 on the front to which they do not adhere. The strips 58 nevertheless also come, as the winding and after a certain number of turns, in contact with the adhesive strips 28. This time, as a result of the choice of the nature of the adhesive of the strip 58 and of its controlled adhesion, there is also the possibility of takeoff and unwinding of the film from a roll.

It should be noted that it is also possible to provide the front side of the film 52 of FIG. 9 with a non-stick coating similar to that of FIG. 10 in order to facilitate the unwinding of a film stored in roller. Instead of providing strips of sealing plaster having a generally rectangular shape as shown in the figures, it is possible to provide strips of ovoid shape. This allows progressive detachment, with less risk of tearing, when the packaging is opened or the film is cut from the roll.

Figure 1 1 is a section, on an enlarged scale, through the thickness, of an example of a film of the embodiment of Figure 10. The different layers, identified by AF, are formed, in this advantageous exemplary embodiment, in the following manner, knowing that layer A constitutes the front side and layer F constitutes the back side: A: latex-type “soft” sealing coating, deposited in a proportion of 2-4 g / m ² , product IP 7985 from SWALE,

B: PVB (polyvinyl butynale) lacquer, product WO 48825 from SWALE with wax additives and having non-stick properties for the coating of layer F and deposited at the rate of 0.7-1.3 g / m ² , C: color printing with PVB ink, Dynavin series, supplied by SWALE and applied at a rate of 2-3 g / m ² ,

D: aqueous "primer", type 200970 from SWALE applied at a rate of

0.4-0.8 g / m ² , E: oriented, coextruded polypropylene film, of the BEZ type, supplied by VIBAC, with a thickness of 30 μ and composed of: E1: metallization layer of 0.02-0 , 04 μ, E2: 1.5 μ coex layer consisting of a mixture of co-polymers and homo-polymers, E3: 27 μ homo-polymer core

E4: homopolymer coex layer with non-stick properties for layer A.

F: dry type cold sealing plaster based on latex deposited at a rate of 2-4 g / m ² , product IP 7983 from SWALE. A film formed in this way can be unwound and wound up to ten times from a reel without losing the adhesive properties necessary for the formation of a closed package.

FIG. 12 represents a simplified variant of the embodiment of FIG. 10. In this variant, the film 62 simply comprises, on the back side, along one of the edges (transverse with respect to the roll film before cutting) , a strip of cold sealing plaster 64 corresponding to the strip 58 of FIG. 10 and, on the opposite edge, on the front side, another cold sealing strip 66, corresponding to the strip 28 of FIG. 10. The constitution of the film can be as described above with reference to FIG. 11. The two strips 64 and 66 have been shown, by way of illustration, and as indicated above, in ovoid form to facilitate detachment during the unwinding the roll.

In other words, in this variant of FIG. 10, the structure 24, 26, 30, 32 of the sealing plaster of FIG. 10 is not used. This variant can be used when an almost hermetic closure as permitted by the embodiments of Figures 9 and 10 is not required and that the closure along the fold lines is not waterproof. On the other hand, the last phase of the packaging constituted by the superposition of the sealing plaster areas 64 and 66 allows the maintenance of the folds carried out previously when the packaging is produced in a machine of the folding box type, that is ie where all the folds mentioned with reference to FIGS. 3 to 6 are produced practically at the same time.

It is also possible to provide a simplified variant similar to that described above for the embodiment of FIG. 9.

Claims

1. Packaging envelope arranged to package an article (34), in particular a food product, this envelope consisting of a film conditioned in the form of a roll and sectionable transversely into separate films (20, 52, 56, 62) intended to be closed by folding around the article (34), characterized in that the film comprises, on each film (20, 52, 56, 64) at least along the transverse edge of the film, a strip of coating cold sealing which ensures a controlled adhesion of the film on itself and which is powerful enough to maintain the closure of the packaging, but which is insufficient to disturb the unwinding of the film from its roll.

2. A packaging envelope according to claim 1, characterized in that the film comprises, on each film, along each transverse edge thereof, a strip of cold sealing plaster (64, 66), l one of the strips (66) located on the front side and the other (64) on the back side of the film.

3. Envelope according to claim 1, characterized in that the front face of each film comprises zones of cold sealing plaster (22) disposed at least partially along three sides at the periphery of the film (20, 52 , 56) in a configuration such that most of these sealing plaster areas are superimposed after the film has been folded around the article, adhere to each other and maintain the folds around said article.

4. Envelope according to claim 3, characterized in that at least one central zone on the fourth side is free of sealing plaster and in that a zone of cold sealing plaster (54) of the soft type is deposited. on the front side of each film (52), at least partially in correspondence with the sealing coating (22) on one of the three sides of this film, said side being opposite to said fourth side having the central zone free of coating sealing.

5. Envelope according to claim 3, characterized in that the back side of each film (56) of said film comprises at least one zone of cold sealing plaster (58) of the dry type arranged to be at least partially superimposed, after folding the film to a strip (28) of the areas of cold sealing plaster (22) on the front side of the film.

6. Envelope according to claim 5, characterized in that said zone of cold sealing plaster (58) deposited on the back side of each film (56) is deposited at least partially in correspondence with the central zone of the fourth free side sealing plaster.

7. Envelope according to any one of claims 1 to 6, characterized in that the sealing coating of the sealing coating strips (54, 58, 64, 66) is spread in the form of an ovoid strip.

8. Envelope according to any one of claims 5 or 6, characterized in that each film (52, 56) comprises, over its entire recto face, a non-stick coating (60) which is applied before the sealing coating. cold sealing plaster areas (22).

9. Envelope according to any one of claims 2, 5 or 6, characterized in that each film (56, 62) comprises, over its entire reverse surface, a non-stick layer (E4) coextruded in the substrate of the film (56, 62).