CZ292932B6 - Packing material - Google Patents

Abstract

The present invention concerns a packing material consisting of a foil capable of being cut up into separate sheets (56, 62) for packaging articles (34) and comprising, on the inner side relative to the article to be packaged (12), in particular a food product, said sheets 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 sheet (56, 62), at least a cold seal coating strip (28, 58, 64, 66) with controlled adherence, ensuring that the folds of the sheets (56, 62) are maintained and the package is closed, following the phases which consist in folding the sheet (56, 62) around the article (34) to be packaged.

Description

Technical field

The invention relates to a packaging material suitable for packaging articles and consists of a packaging film which is divided into separate sheets intended to be folded over a wrapped article.

Rather, without being limited to the field of application, the invention relates more to the field of packaging of confectionery and chocolate products or other food products such as soup cubes.

BACKGROUND OF THE INVENTION

The articles are generally individually wrapped in a rectangular sheet, preprinted wrapping film of appropriate size and shape, wherein the individually wrapped articles may in turn be loosely packed in a packing bag of suitable size. For example, a packaged product having a parallelepiped shape is placed in the middle of the back side, i.e. the unprinted side of the rectangular wrapping sheet, according to a conventional packaging method. The two longitudinal sides are then bent vertically upward (or downward, depending on the location of the product and the type of packaging machine) around the two longitudinal sides of the product. Thereafter, the lateral sides are folded vertically around both sides of the article and their upper edges folded flatly around the upper surface of the article, the latter two operations necessarily being carried out by successive and oblique bending, with the previously bent longitudinal sides. The packaging is completed by folding the upper edges (which in the meantime become trapezoidal flaps) of the longitudinal sides over each other, around the top surface of the article.

It should be noted, however, that depending on the shape of the product to be packaged and the type of packaging machine, another sequence of bending operations of the wrapping film is possible, wherein this sequence of bending operations is carried out according to well-defined fold line arrangements. This arrangement of fold lines of the wrapping film always remains the same for the same product packaged in the same way.

A significant problem that arises here is the maintenance of the bends after the wrapping operation to keep the package open. This bending maintenance can only be ensured at the cost of a special selection of the foil to be used as the substrate, which must exhibit suitable mechanical properties, such as flexibility, and in particular a strong tendency not to return to its initial position after bending the foil sheet during packaging.

This problem is particularly evident when packaging small products such as confectionery products such as sweets, pralines, lollipops, sugar candy, chocolate bars, etc., or soup cubes.

A known solution is to select a substrate particularly known for its flexibility, such as paraffin paper, cellophane, aluminum laminates, or still a synthetic film containing a suitable amount of additives that increase the flexibility of the substrate.

However, this solution greatly reduces the choice of film used as a backing for packaging or significantly increases costs.

Also known are packaging films for various products, such as soup cubes, where the closure of the package is secured by gluing. For this purpose, the foil has a hot-bonding layer on the front side, i.e. the outside of the packaged product, whose arrangement is adapted to the arrangement of folds formed during the packaging.

This packaging method has the disadvantage that the packaging machine must be specially adapted to this method to the extent that a heat source is required. In addition, if this heat source is

As a result of heating plates, gluing can only be carried out on perfectly planar surfaces of the packaged product, requiring, in addition to the time required for welding, a relatively significant pressure which cannot withstand a certain number of products.

A further disadvantage is that this method of packaging is completely unsuitable for packaging heat-sensitive products, especially chocolate products, and does not allow selection of a substrate for packaging having poor temperature resistance.

Patent application EP 0 870 695 proposes a wrapping film intended to be closed around an article, the front side of which, i.e. the side outside the article, has a cold adhesive layer disposed in such an arrangement that the adhesive areas overlap folding the wrapping film around the product. Therefore, these adhesive areas ensure the maintenance of bends when the wrapping film material has such a property that it does not maintain these bends. However, the wrapping film is provided with a hot-melt coating which keeps the wrapping film closed and which has the above-mentioned disadvantages. This wrapping film also has the further disadvantage that the back side must comprise anti-adhesive tapes to allow the film to be unwound from the reel.

EP 0 225 987 discloses a packaging film having, on the front and on the back side, a cold-gluing area, namely two longitudinal strips on the front and on the back, respectively. In order to make this film in a form wound on a reel, these different adhesive areas must be positioned so that they do not overlap during winding. In fact, such an overlap would cause these different regions to stick together and prevent the foil from unwinding from the reel. However, this restriction, as far as the location of the adhesive area is concerned, includes a restriction corresponding to the configuration of the bends and the packaging methods.

In fact, the aforementioned documents pursue the same objectives, namely to apply an adhesive area to the film, to maintain folds and to provide the film with a condition wound on the reel. The problem lies in how it is further described that if the film comprises two self-adhesive regions on the back and front when it is wound on a bobbin, there is a risk that some of these adhesive regions of two adjacent windings overlap on the bobbin and stick together , which would prevent the foil from unwinding from the spool.

These two writings attempt to solve this problem by various means. EP 0 870 695 envisages the use of an adhesive layer region for cold bonding only on the front side. Therefore, there is no danger of overlapping each other during winding. On the other hand, in order to solve the problem of keeping bends, this document envisages a hot-stick coating on the back, which leads to the aforementioned disadvantages.

EP 0 225 987, on the other hand, seeks a special arrangement of the adhesive layer for cold backing with respect to the layers on the front side and vice versa, so that during winding the two adjacent windings are arranged side by side and there is no overlap. However, this solution imposes limitations on packaging methods in that it is necessary to determine the bending arrangement according to the location of the adhesive areas, although this is the opposite of what is required.

SUMMARY OF THE INVENTION

It is an object of the present invention to provide a new package which allows to significantly extend the selection of the film used and which makes it possible to convert the film into a reel without any restriction as to the packaging method.

In order to achieve this objective, a packaging material according to the invention is provided according to the invention.

Surprisingly, the Applicant has discovered that pre-coating, at least partially, the film used as packaging material with a well-defined cold-bonding layer will allow bending,

Showing the excellent bending after closure of the wrapping film by bending, and at the same time allowing the film to be wound on the reel.

This fact, that the fabric used as an adhesive layer, shows little or no adhesion to a smooth surface or a surface prepared for this purpose, but, on the other hand, exhibits good adhesion when applied to itself, is a case of bending. Thus, bending maintenance is simply ensured by lightly squeezing and offsetting certain areas of the adhesive layers, and this is accomplished without any accessories other than those required to bend the package.

The term cold bonding according to the present invention refers to bonding which occurs immediately, by simple contact, at a temperature of about 0 to 50 ° C. In fact, temperature is not a critical parameter when it comes to achieving adhesive bonding with a cold bonding layer and has virtually no effect on the quality of the bonded joint obtained. Thus, the bonding can be achieved without any additional heat supply, at the ambient temperature of the environment in which the packaging unit is located.

In fact, to date, adhesive layers have been used for cold bonding primarily to layers on a substrate that are not subject to deformation or are subject to only slight deformation. In fact, considerable blocking problems can be expected due to the self-adhesive properties of the cold bonding adhesive to the non-planar substrate.

Thus, the present invention allows for the use of cheaper films and exhibits improved properties (stiffness, printability, aesthetic appearance) for packaging products without limiting the shape of the products.

With regard to the use of rigid films, it should be noted that rigid films have not yet been used for packaging that must be closed by bending. Indeed, these films have a very low bending ability.

Regarding the problem of treating the winding film in comparison with the solutions in the two prior art publications, this application creates a completely different solution, which has been impossible to achieve so far, which consists in tolerating the offset of the different adhesive regions relative to one another. foil adapted to be wound onto a spool. To this end, the invention provides a selection of a well-defined cold-bonding adhesive layer which represents what is defined in the application under the term "controlled adhesion", i.e. adhesion strong enough for the purpose of the case but insufficient to prevent repeated peeling. Thus, the film may be unwound several times from the storage reel, without excessive resistance, even from the inner winding where compression is normally higher. This solution, of course, has significant advantages over the solutions suggested in the foregoing documents, within the limits where the same adhesive can be provided everywhere (i.e. more than for hot bonding) and where adhesive areas can be secured at the desired locations depending on the shape of the packaged product and the bending sequence.

According to a preferred embodiment, the backsheet region structure comprises two W-shaped tape structures, along two opposite sides of the wrapping film, one strip along the third side of the wrapping film, and between the two W-shaped tape structures and two areas at two corners of the fourth side of the wrapping film.

The tapes with adhesive layer, positioned according to the bending arrangement, may have a width of about 4 mm.

The structure of the adhesive strips may have different shapes, depending on the product to be packaged and the bending sequence.

In addition to the tape structure along the bends to be performed, each wrapping film sheet may comprise an adhesive layer tape along the edge of the third side. This strip is located on the flap which, at the end of the packaging process, will be folded first to the base of the packaged product and will provide gluing

-3GB 292932 B6 with the flap that will be folded last. In addition, each sheet of wrapping film may include additional adhesive areas to allow the flap that is folded last to the base of the packaged product to be adhered to, thereby contributing to maintaining the closure state of the package.

According to one aspect of the invention, the adhesion achieved by overlapping the tapes with the adhesive layer for cold bonding is not irreversible, since it must allow the film to be unwound when the film is treated and deposited on the reel without the risk of tearing it. In other words, it is necessary to select an adhesive layer depending on the second substrate on which it is applied, on the one hand its own adhesion on itself is sufficiently weak to allow the wrapping film to unwind from the spool, and on the other hand it is sufficiently strong to provide a quasi hermetic sealing the packaging. So we can talk about controlled grip. This controlled adhesion has, inter alia, the advantage that the package can be opened and closed several times without appreciably reducing the quality of the adhesion.

As mentioned above, one of the advantages of the present invention is that it allows the use of a wide range of options as to the type of substrate used. Examples of suitable substrates are plastic films of about 10 to 100 microns thick, of extruded and oriented polypropylene, of polypropylene in cast film, of polyester, of polyethylene, of extruded and oriented polyamide, or of polyamide in the form of cast film.

According to the invention, it is also possible to use a paper substrate (glazed or coated). Generally speaking, any treasury material or any flexible packaging material may be suitable as a substrate according to the present invention. These different substrates may consist of a single layer, a single metallized layer, or multiple layered layers and / or coextruded layers.

Generally speaking, pressure-sensitive adhesives are compounds based on natural and / or synthetic rubber associated with treated cellophane, phenol-formaldehyde resins, or hydrocarbon resins (waxes). In addition to rubbers, styrene-based polymers, (meth) acrylic acids or vinyl ethers, alone or in admixture, and also in combination with resins, are widely used. In particular, compounds containing mixtures of natural and synthetic rubber and copolymers of (meth) acrylic acid and styrene are used.

According to the present invention, the cold-bonding layers are applied to the substrates in an amount of about 1 to 5 g / m ² . The cold-bonding layers can be applied in the form of a solution, dispersion or even in the molten state.

Overview of the drawings

Further features and features of the invention will become apparent from the following detailed description of several preferred embodiments, with reference to the accompanying drawings, in which: Figure 1 shows the front side of an exemplary embodiment of a wrapping film sheet; Fig. 1 shows the front side of the exemplary embodiment of Fig. 1, supplemented with the adhesive structure on the back, Fig. 11 is an enlarged scale and cross-sectional view of the exemplary embodiment of Fig. 10, and Fig. 12 shows a simplified variant of the embodiment of Fig. 10.

DETAILED DESCRIPTION OF THE INVENTION

FIG. 1 shows the front side or the printed side of the wrapping film sheet 20, after being cut off from the film unwound from the storage coil (not shown), in the direction shown by the arrow A.

The cold-bonding adhesive layer is disposed in the structure 22, which is adapted to the configuration of the fold lines formed in the package, an example of which will be described hereinafter. When

Fig. 1 shows two structures of the strips 24 and 26, approximately ± 4 mm wide, approximately W-shaped, along opposite sides of the wrapping film sheet 20, and the strip 28 along the third side of the wrapping sheet film 20 between two W-shaped side structures. On the opposite side to the tape 28, there are also two cold bonding regions 30 and 32 in the corner region. With respect to the film initially deposited on the reel, the strips 24 and 26 are positioned along the longitudinal edges, while the strip 28 is positioned transversely. On the reel, these different adhesive-coated tapes on the front are located on the outside of the various coil windings.

Sheet 20 of the wrapping film of Figure 1 can be made by depositing a thin printed layer or primer (e.g., SIEGWERCK 10-612205-4 MX41) to improve ink adhesion, on the front side of a 25 micron oriented polypropylene film, metallised or unmetallised. The coating is applied by printing techniques known per se, for example by heliographic or flexographic techniques, or by offset printing. A protective varnish, which is also known per se, is also applied to the printing. Cold lacquer structures 22 are applied to the lacquer according to the pattern shown in FIG. 1. This deposition can also be performed by printing techniques known per se.

For cold bonding, SWALE's IP7905 or IP7936 can be applied at a rate of, for example, 3 g / m ² . This is an adhesive layer that adheres only to itself. In other words, this layer does not adhere to the untreated smooth back of the film, allowing the film to be simply placed and adapted for the reel, without any unwinding problem. Moreover, this adhesive layer is of such a quality that it has a low coefficient of friction (COF) on the metal which is in the range of 0.2 to 0.6, whereas this coefficient of friction (COF) on the metal is normally in the range of 1 to 1 , 5. This low coefficient of friction reduces the risk of creasing and sticking to the bent box.

Referring to Figures 2 to 8, a substantially parallelepiped candy wrapping operation will be described in the wrapping sheet 20 of Figure 1. This sheet 20 is placed on the candy 34 with its back or untreated side facing the candy 34 so that the strip 28 and the opposite side with the adhesive regions 30 and 32 were placed in the longitudinal direction of the candy 34, and the W-shaped structures were placed in the transverse direction of the candy 34. The sides of the wrapping sheet 20 are then bent down over the longitudinal walls of the candy 34 shown in FIG.

In the following operation, the center region of each side of the wrapping film sheet 20, with the structures 24 and 26, is folded onto the sidewalls of the candy 34 as shown in Figure 3. This operation is performed by bending with the longitudinal sides of the wrapping sheet 20 following oblique bending lines. 36 and 38. As can be seen in Fig. 3, both W-shaped structures 24 and 26 (where structure 26 is not visible in Fig. 3) with adhesive layer are positioned such that the two outer members of these W-shaped structures The "W" runs along the bending lines 36 and 38, and the V-shaped inner part is placed on the side of the candy 34 ·

In the following operation, two sides of the film delimited by fold lines 36 and 38 are folded inwardly from each side of the candy 34 in the direction of arrows 1 and 2 in Figure 3. This operation places the outer strips of the "W" adhesive layer structures that is, these strips extend along the bend lines 36 and 38 on the inner ribbons of the "V" shape and the result is the arrangement shown in Fig. 4. Obviously, this bending sequence takes place on both sides of the candy 34. that the tapes of the two W-shaped structures 24 and 26 are completely offset from each other and that the cold adhesive used adheres perfectly to each other, the arrangement of FIG. 4 being a stable arrangement with perfect maintenance of the bends hitherto performed.

The following bending sequence is shown in FIG. 5 and bends the lower portions of the side walls which have been bent and folded in advance to the underside of the candy 34. This operation is performed by bending, with longitudinal sides following the oblique fold lines 40, 42, 44, 46, which

The result of this bending sequence is clearly seen in Fig. 6, representing a bottom and side view obscured in the preceding figures.

It should be noted here that the two cold adhesive regions 30 and 32 are positioned so that their oblique inner edges (see also FIG. 1) extend along the fold lines 40 and 42 of the flap 48 as seen in FIG. 6. .

Giant. 7 and 8 show the final stage of packaging. First, the flap 50 provided with the adhesive layer strip 28 is folded to the inner side as shown in FIG. 7. The second flap 48 is then folded over the flap 50 to form the arrangement of FIG. 8.

When the flap 48 is folded, the two adhesive regions 30 and 32 are partially overlapped to each other, and are applied to the tape 28 with the adhesive layer of the flap 50. As a result, assuming the flap 48 adheres to itself and the flap 50, Fig. 8 is a stable configuration with good maintenance of all bends.

It should be noted, however, that when the flap 48 is folded over the flap 50, the adhesive tape 28 only adheres to the adhesive areas 30 and 32 by its overlap. In contrast, its middle portion contacts the back of the flap 48 to which it does not adhere. In other words, if the wrapping film sheet 20 of FIG. 1 provides a package with a stable and durable closure, it does not provide a sealed package.

Each packing sequence described below is carried out automatically in a packaging machine. In this context, it is important to note that the proposed wrapping film sheets 20 are suitable for existing packaging machines, without the need for any modification or adaptation. It should be noted, however, that the package described below is only an example of a bending arrangement on a designated machine. On other machines bending can be performed according to different bending line arrangements. In this case, it would be appropriate to adapt the pattern of adhesive structures shown in FIG. 1 to the configuration of the bending lines performed by the bending machine, the opposite process being more difficult.

FIG. 10 shows a preferred embodiment of a wrapping sheet 56 according to the present invention.

Oriented polypropylene foil can be used again, which is suitably printed, possibly after application of the primer. An anti-adhesive layer 60 is then applied to the entire front surface. Suitable anti-adhesive products consist of a mixture of polyamide resin and polyethylene wax (for example SIEGWERCK 10-609345-3P and SICPA 994404-X) applied at 1.5 g / m ² . A pattern of cold glue layer structure 22 is then applied to this layer, as in FIG. 1. A cold glue layer 58 is then applied to the back, approximately between the front side regions 30 and 32 as shown in FIG. 10 in dotted lines. When using a wrapping film sheet 56 for the packaging described in Figures 2 to 8, the adhesive layer strip 58 will be positioned at the end of the wrapping operation (see Figure 7) on the inside of the flap 48 and will adhere to the tape after folding. 28 with a flap adhesive layer 50, to form a quasi-hermetic wrapper.

When the film of FIG. 10 is deposited on the reel, the backsheets 58 with the backsheet generally contact the non-adhesive backsheet 60 on the backside on which they do not adhere. However, the adhesive-coated tapes 58, however, also come into contact with the adhesive-coated tape 28 during unwinding and after several windings. In this case, by selecting the type of adhesive for the tapes 28 and 58 and its controlled adhesion, there is also the possibility of peeling and unwinding the film from the reel, without advancing the film and without significantly reducing the adhesive properties of the tapes 28 and 58.

Instead of providing the tapes with an adhesive layer having a generally rectangular shape as shown in the figures, oval-shaped tapes may be used. This arrangement allows for gradual release, with less risk of tearing, when opening the package or unwinding the film from the reel.

-6GB 292932 B6

FIG. 11 shows, on an enlarged scale and in cross-section, the thickness of the wrapping film sheet of FIG. 10. In this preferred embodiment, different layers are designated A to F, where layer A forms the front side and layer F the rear side. side:

A: latex-based adhesive layer applied at 2 to 4 g / m ² , SWALE IP 7985,

B: PVB (polyvinyl butynal), product WO 48825 SWALE with wax additives and anti-adhesive properties for coating of layer F and applied at 0.7 to 1.3 g / m ²

C: PVB color print, Dynavin series, provided by SWALE and applied at 2 to 3 g / m ² ,

D: primer - aqueous solution, type 200970 from SWALE, applied at 0.4 to 0.8 g / m ² ,

E: oriented polypropylene film, coextruded, type BEZ, provided by VIBAC, thickness 30 μ and consisting of:

El: metallized layers with a thickness of 0,02 to 0,04 μ,

E2: coextruded layers of 1 μ thickness, consisting of a mixture of copolymers and homopolymers,

E3: 27 μm homopolymer cores,

E4: co-extruded layers of homopolymers with anti-adhesive properties for layer A.

F: Latex-based cold adhesive, 2 to 4 g / m ² , SWALE IP 7983.

The film thus formed can be unwound and wound up to ten times on and out of the spool without losing the adhesive properties needed to form a sealed package.

Fig. 12 shows a simplified variant of the embodiment of Fig. 10. In this variant, the wrapping film sheet 62 simply comprises on the back, along the edges (transverse to the film wound on the reel, before cutting it), a tape 64 with an adhesive layer. 10, and at the opposite edge from the front side, another cold-sealing tape 66 corresponding to tape 28 of FIG. 10. The composition of the wrapping sheet 62 may be as described above in accordance with the present invention. Fig. 11. Both tapes 64 and 66 have been shown for explanation, and as indicated above, are in an egg shape to facilitate release when unwinding from the spool.

In other words, in this variation of FIG. 10, the adhesive layer structure 24, 26, 30, 32 of FIG. 10 is not used. This variation can be used when a quasi-hermetic seal is not required, which is possible according to the embodiment of FIG. 10, and when the closure along the bending lines is not sealed. On the other hand, the last phase of the package formed by the offset of the adhesive areas 64 and 66 allows the pre-formed folds to be maintained when the package is made in the bent-box machine, i.e. when all the errors shown in Figures 3 to 6 are practically simultaneous.

Claims (4)

Packaging material for the treatment of products (34), in particular food products, obtained from a film wrapped in a longitudinal direction on a spool and divided transversely into separate sheets (56, 62) for closing by bending around the product (34), characterized in that that said film comprises a strip (28, 58) along each transverse edge (56, 62), 10, 64, 66) with a cold-bonding adhesive layer, wherein one strip (28, 66) is located on the front transverse side and the other strip (58, 64) is located on the back transverse side of said sheet (56, 62), (28, 58, 64, 66) is ensured by their offset by the final closure of the wrapper after the last sheet bending sequence (56, 62), wherein the mutual adhesion between the tapes (28, 58, 64, 66) is controlled adhesion sufficient to maintain closure but not sufficient to interrupt the unwinding of the film from its spool when the sheets (56, 62) contact each other in a wound state on the spool between the front transverse side strap (28, 66) and the rear transverse side strap (58, 64). Packaging material according to claim 1, characterized in that the front side of the sheet (56) comprises a cold-bonding adhesive structure (22) disposed at least partially along three 20 sides at the edge of the sheet (56), in such an arrangement that most of its regions are offset after the sheet (56) is bent around the article (34) adhering to each other and maintaining bends around the article (34). Packaging material according to claim 1 or 2, characterized in that the adhesive layer of the strip (58, 64) is disposed in the shape of an oval strip on the back of the sheet (56, 62). Packaging material according to claims 1 to 3, characterized in that the sheet (56, 62) comprises on the entire front side an anti-adhesive layer (60) applied under the adhesive layer in the region of the cold adhesive layer.