EP0870695A1 - Polyolefin film for making a package by folding - Google Patents

Abstract

The polyolefin-based film has an outer face with a cold sealing layer and an inner face with an anti-adhesion surface. The cold-sealing material is applied to the outer surface in set areas (20) which are sealed on contact as the material is folded. The polyolefin-based material for the film is selected from polypropylene (PP), from OPP, metallised OPP or expanded PP with a mother-of-pearl finish. The anti-adhesion surface is produced by a coating of varnish made from, e.g. alkyl acrylate and natural latex. Other materials which can be used for the film are, for example, PVDC or EVOH.

Description

FIELD OF THE INVENTION

The invention relates to flexible films used in the packaging of solid portions or semi-solid by folding. As an example of packaged solid or semi-solid portions in flexible films, mention may be made of food products such as broths KUB ®.

STATE OF THE ART

1) à partir d'une bobine de film, est découpée une portion de film sur lequel est placé ledit bloc,

2) l'ensemble est placé dans une boíte de pliage qui permet de réaliser la succession des plis nécessaires à l'emballage dudit bloc par ladite portion de film, de manière à obtenir un bloc emballé plié,

3) ledit bloc emballé plié circule entre des rails chauffants qui fondent la cire. Celle-ci diffuse dans le papier mousseline et assure ainsi le collage des différents plis formés en 2). On obtient ainsi un bloc emballé collé. Les blocs emballés collés sont ensuite regroupés dans un suremballage, typiquement une cartonnette.

For the typical packaging of food products such as KUB ® broths, a complex film is generally used successively consisting of a thin sheet of aluminum lacquered golden on the outside, a layer of wax in the center, and a layer of tissue paper inside, or in condensed designation: Al / wax / paper. KUB ® broth blocks are packaged as follows, on an automatic machine:

1) from a film reel, a portion of film is cut on which said block is placed,

2) the assembly is placed in a folding box which makes it possible to carry out the succession of folds necessary for packaging said block by said portion of film, so as to obtain a folded packaged block,

3) said folded packaged block circulates between heating rails which melt the wax. This diffuses into the tissue paper and thus ensures the bonding of the different folds formed in 2). This produces a packaged, glued block. The glued packaged blocks are then grouped in an overwrap, typically a cardboard box.

PROBLEMS POSED

• d'une part, il a été observé que les films traditionnels conduisaient à des perces, en particulier aux coins desdits blocs, peut-être à la fois par l'action mécanique des coins desdits blocs sur ledit film, et éventuellement par l'action corrosive de grains de sel dudit bloc dans le cas de bouillons KUB ®.
• d'autre part, le bloc emballé collé est relativement difficile à ouvrir.
• enfin, le film traditionnel est d'un coût relativement élevé.

The problems posed by traditional packaging film are of three types:

• on the one hand, it has been observed that traditional films lead to drilling, in particular at the corners of said blocks, perhaps both by the mechanical action of the corners of said blocks on said film, and possibly by the action corrosive to grains of salt from said block in the case of KUB ® broths.
• on the other hand, the glued pack is relatively difficult to open.
• finally, traditional film is relatively expensive.

DESCRIPTION OF THE INVENTION

a) il comprend un film à base de polyoléfine,

b) la face extérieure dudit film comprend une couche de scellage à froid formant des plages repérées,

c) la face intérieure dudit film comprend une couche anti-adhérente, éventuellement repérée par rapport auxdites plages repérées.

According to the invention, the film for packaging rigid or semi-rigid blocks consisting of walls formed by folding and sealing said film is characterized in that,

a) it comprises a film based on polyolefin,

b) the outer face of said film comprises a cold sealing layer forming marked areas,

c) the inner face of said film comprises a non-stick layer, possibly marked with respect to said marked areas.

• un film à base de polyoléfine peut être choisi parce que, d'une part il possédera les caractéristiques mécaniques suffisantes et il constituera le plus souvent une barrière suffisante à l'humidité pour le produit à conditionner, et d'autre part son coût est relativement bas.
  S'il était exigé du film selon l'invention une faible perméabilité à l'oxygène, ledit film à base de polyoléfine pourrait, de manière connue, soit être métallisé, soit être remplacé par un film multicouche comprenant une couche de matériau à propriétés barrières, tel que les copolymères de chlorure de vinylidène (PVDC) ou les EVOH.
• une couche de scellage à froid est nécessaire pour que, lors de l'emballage dudit bloc dans une portion découpée dudit film en utilisant généralement une boíte de pliage, le scellage desdites plages repérées s'effectue immédiatement par simple contact des parties mises en regard lors dudit pliage, au moins une des parties mise en regard lors dudit pliage étant recouverte d'une couche de scellage à froid. Ainsi, en sortie de boíte de pliage, ladite portion de film, une fois pliée, n'aura plus la possibilité de se déplier, compte tenu de l'effet mémoire des films de polyoléfine.
• ledit film à base de polyoléfine doit comprendre une couche anti-adhérente, éventuellement repérée par rapport auxdites plages repérées, parce que, sans cela, on observerait un collage en bobine : la couche de scellage, déposée sur la face extérieure dudit film, collerait ou risquerait de coller à la face intérieure de la spire adjacente. Les traitements d'anti-adhérence, destinés notamment à éviter le collage entre les spires d'une bobine de film, sont bien connus en eux-mêmes.

The invention requires the combination of the means described above:

• a polyolefin-based film can be chosen because, on the one hand it will have sufficient mechanical characteristics and it will most often constitute a sufficient barrier to humidity for the product to be packaged, and on the other hand its cost is relatively low.
  If the film according to the invention were required to have a low oxygen permeability, said polyolefin-based film could, in known manner, either be metallized or be replaced by a multilayer film comprising a layer of material with barrier properties , such as vinylidene chloride copolymers (PVDC) or EVOH.
• a cold sealing layer is necessary so that, during the packaging of said block in a cut portion of said film, generally using a folding box, the sealing of said identified areas is carried out immediately by simple contact of the facing parts during of said folding, at least one of the parts facing each other during said folding being covered with a cold sealing layer. Thus, at the outlet of the folding box, said portion of film, once folded, will no longer have the possibility of unfolding, taking into account the memory effect of polyolefin films.
• said polyolefin-based film must include a non-stick layer, possibly marked with respect to said marked areas, because without this, a bonding on a reel would be observed: the sealing layer, deposited on the outside of said film, would bond or may stick to the inside of the adjacent coil. Anti-adhesion treatments, intended in particular to avoid sticking between the turns of a film reel, are well known in themselves.

Thanks to this combination of means, it was possible to solve the problem posed. Indeed, the film according to the invention has a much better resistance to the risk of punctures than the traditional film based on thin aluminum foil, and this both by the better mechanical resistance to punctures by the better resistance to corrosion. In addition, the invention, which has succeeded in combating the memory effect of the thermoplastic films during the folding phase, uses this same memory effect to facilitate the unfolding of said block by the end consumer.
Finally, given the relatively low cost of polyolefin films compared to the cost of thin aluminum sheets, the film according to the invention is significantly more economical than the films according to the prior art.

DESCRIPTION OF THE FIGURES

Figure 1 is a top view of the outer face of the film or portion of film (1) intended to form a package of a rigid or semi-rigid parallelepipedal block having a rectangular base of 32mm x 23mm, and 10 mm height.
The four marked areas (20) of cold sealing layer, hatched vertically, correspond to the formation, by folding, of the four side walls of the package to be formed.
Each of the four areas (20) comprises two parts (201, 202) which, after folding along the lines (203), are opposite and adhere to each other, thus fixing the side walls of the package to be formed .

The four marked areas (21) of cold sealing layer, hatched horizontally, correspond to the formation, by folding, of the upper wall of the package to be formed.
Each of the four areas (21) comprises two parts (211, 212) which after folding along the lines (213), are opposite and adhere to each other, thereby fixing the upper wall of the package to be formed.
On the film (1) is carried an arrow (6) indicating the direction of unwinding of the film on reel.

FIG. 2 is a bottom view of the interior face of the film or portion of film (1), having the same lateral positioning as in FIG. 1.
This inner face includes two lateral strips (3) non-stick, so that the marked areas (20,21) of the outer face do not adhere to the inner face and thus allow the unwinding of the film reel.
Between these two strips, and at one end of the portion (1) of film, is a marked area (4) of heat-applied varnish.
This area (4) is located a distance of 10 mm from the edge, so as to leave an opening zone (6) constituting for the consumer an easy grip of the film for the opening of the packaging formed.

DETAILED DESCRIPTION OF THE INVENTION

According to one embodiment of the invention, the location of said cold sealing layer is chosen as a function of said folding, so that, during said folding, any identified area or portion of identified area is brought into contact, respectively, or from another marked area, or from another part of the same identified area, so that, after folding of said block, no free cold sealing layer remains.
By cold sealing layer is meant a generic family of adhesive products, often known in themselves as "coldseals", and which have the particularity of adhering cold to themselves.

According to another method, not shown in the figures, cold active adhesives can be used which can adhere to said polyolefin-based film, but which do not adhere to this same film made non-stick.
In this case, said marked areas of cold sealing (20,21) are of half the surface area and are limited to one half (201, 211) of area (20,21).

According to the invention, said polyolefin-based film is preferably chosen from PP, OPP, metallized OPP, expanded PP with pearlescent appearance.

According to the invention, the inner face of said film must include a non-stick layer, possibly marked with respect to said marked areas.
For this, either the inner face of said PP-based film is made non-stick, or the inner face of said PP-based film is coated with a layer of non-stick varnish. In the second case, this layer of varnish (3) can be identified, as illustrated in FIG. 2.

According to another embodiment of the invention, said interior face can comprise said non-stick varnish in a marked layer, and a heat-sealing varnish in another layer marked, and offset with respect to said cold sealing layer, so that, in said film on reel, a layer of cold sealing of the external face of a turn, is not facing said layer of heat-sealing varnish from another turn. This modality is intended to increase, when it is made necessary in particular by local climatic conditions, the tightness of the packaging formed, the sealing of beaches (20,21) only ensuring that the packaging formed is not likely to unfold.

Another object of the invention consists of the use of a film according to the invention for packaging food products in the form of rigid blocks or semi-rigid.

EXAMPLE OF IMPLEMENTATION

A film was made as shown in Figures 1 and 2.

A 32 µm thick OPP film was used with one side made non-stick. On its outer face, a thickness of 4 μm of a commercial cold-sealing varnish (varnish based on acrylate) has been deposited, marked and along the ranges (20, 21) of FIG. 1 alkyl and natural latex).
On its inner face, a layer (4) of commercial fusible varnish (varnish based on alkyl acrylate) 4 μm thick was deposited.

We used this film to wrap KUB ® broth blocks on a standard machine with folding boxes.
No particular problems were observed during the packaging of these blocks, which were then placed in cardboard.
During transport and storage, no perforation of the said film was observed.
The final opening by the consumer has proved easier than that of the packaging according to the prior art, the polyolefin-based film having a tendency, once the links between the sealed sides have broken, to return to its shape initial plane.

Claims (7)

Film for packaging rigid or semi-rigid blocks consisting of walls formed by folding and sealing said film, characterized in that, a) it comprises a film based on polyolefin, b) the outer face of said film comprises a cold sealing layer forming marked areas, c) the inner face of said film comprises a non-stick layer, possibly marked with respect to said marked areas. The film of claim 1 wherein the marking of said sealing layer at cold is chosen according to said folding, so that, during said folding, all track marked or part of track marked either brought into contact, respectively, or of a other marked range, or from another part of the same marked range, so that, after folding of said block, no free cold sealing layer remains. A film according to any of claims 1 to 2 wherein said film based polyolefin is chosen from PP, OPP, metallized OPP, expanded PP with pearlescent appearance. The film of claim 3 wherein the interior face of said PP-based film is made non-stick. The film of claim 3 wherein the interior face of said PP-based film is coated with a layer of non-stick varnish. The film of claim 5 wherein said interior face comprises said varnish non-stick in a marked layer, and a heat-sealing varnish in another layer marked, and offset with respect to said cold sealing layer, so that, in said film on reel, a layer of cold sealing of the external face of a turn. is not facing said layer of heat-sealing varnish from another turn. Use of a film according to any one of Claims 1 to 6 for packaging of food products in the form of rigid or semi-rigid blocks.

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