EP0990596B1 - Polyolefin film for making a package by folding - Google Patents

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

For the typical packaging of food products such as KUB ® broths, generally uses a complex film successively consisting of a thin sheet of aluminum printed color and / or with a heat-sealing lacquer on the outside, said lacquer being applied by area or flat over the entire surface, from a layer of wax to center, and a layer of tissue paper inside, or in condensed designation: Al / wax / paper.

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 font sceller la laque thermoscellante contre elle-même ou qui fondent la cire, celle-ci diffusant dans le papier mousseline et assurant ainsi le collage,

4) On obtient ainsi un bloc emballé collé. Les blocs emballés collés sont ensuite regroupés dans un suremballage, typiquement une cartonnette

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 the packaging of 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 seal the heat-sealing lacquer against itself or which melt the wax, the latter diffusing in the tissue paper and thus ensuring bonding,

4) This gives a glued packaged 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,
• en outre, l'emploi de cire peut entraíner un risque de migration dans le produit conditionné,
• enfin, le film traditionnel est d'un coût relativement élevé.

There are four types of problems with traditional packaging film

• on the one hand, it has been observed that traditional films lead to holes, 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 of grains of salt of said block in the case of KUB® broths,
• on the other hand, the glued pack is relatively difficult to open,
• in addition, the use of wax may cause a risk of migration into the packaged product,
• 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 externe d'un produit de thermoscellage à basse température formant des plages repérées, de manière à obtenir, après ledit thermoscellage qui suit ledit pliage, ledit emballage à parois fixées de manière stable, ledit produit de thermoscellage présentant une fonction de scellage activée à une température allant de 60°C à 110°C.

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

a) it comprises a film based on polyolefin,

b) the outer face of said film comprises an outer layer of a low-temperature heat-sealing product forming marked areas, so as to obtain, after said heat-sealing which follows said folding, said packaging with walls fixed stably, said product heat sealing having a sealing function activated at a temperature ranging from 60 ° C to 110 ° C.

In addition, as is known to a person skilled in the art, the formation of marked areas of a virtually colorless product requires the printing of a spot, to adjust the pitch of the packaging machine which has to cut said film into portions of film, each portion being intended to package each said rigid block.

By low-temperature heat-sealing product is meant products whose sealing function is activated and carried out at relatively low temperatures ranging from 60 ° C. to 110 ° C., in contrast to conventional heat-sealing products activated at higher temperatures, and as opposed to products operating at room temperature (called “cold-seals”).
These low temperature heat sealing products are typically resins or mixtures of resins based on EVA, copolymers of PVC or acrylics.

• 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 couché d'une enduction barrière comme par exemple de l'EVOH, 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.
• la couche de produit de thermoscellage à basse température permet, lors de l'emballage dudit bloc emballé plié qui circule entre des rails chauffants assurant le thermoscellage des couches en regard comprenant dudit produit de thermoscellage à basse température, de garantir le scellage desdites couches en regard sans courir le risque d'endommager, par une température excessive, ni ledit film, ni l'aliment contenu dudit emballage.

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 coated with a barrier coating such as for example EVOH , or be replaced by a multilayer film comprising a layer of material with barrier properties, such as vinylidene chloride copolymers (PVDC) or EVOH.
• the layer of low-temperature heat-sealing product makes it possible, during the packaging of said folded packaged block which circulates between heating rails ensuring the heat-sealing of the facing layers comprising said low-temperature heat-sealing product, to guarantee the sealing of said facing layers without running the risk of damaging, by excessive temperature, either said film or the food contained in said packaging.

Thanks to this combination of means, it was possible to resolve all of the problems raised. Indeed, the film according to the invention has a much better resistance to risks of perforation than traditional film based on thin aluminum foil, and this by better mechanical resistance to drilling than by better resistance to corrosion. In addition, the invention uses the memory effect to facilitate the unfolding of said block by the end consumer.

By their nature, the films according to the invention do not present any risk of migration of products to packaged food, and therefore eliminate the risk of wax migration which can take place with a structure based on Alu / wax / muslin.

Finally, given the relatively low cost of polyolefin films compared to the cost thin aluminum sheets, the films according to the invention are significantly more economical than films according to the state of the art.

DESCRIPTION OF THE FIGURE

Figure 1 is a top view of the outer face of a portion of film (1) intended to form a packaging of a rigid or semi-rigid parallelepiped block having a rectangular base of 34mm x 24mm, and 12 mm height.
The four marked areas (20) of a layer of low temperature heat-sealing product, 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 layer of low temperature heat-sealing product, 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, thus fixing the upper wall of the package to be formed
On the film portion (1) is carried an arrow (6) indicating the direction of unwinding of the film on the reel, and a marking spot (3) intended for cutting said film into portions (1) of film.

DETAILED DESCRIPTION OF THE INVENTION

According to one embodiment of the invention, said film is such that at least the part of the inner face of the last ply of said fold comprises an internal layer of a heat-sealing product, so as to improve the closing of the last ply by final sealing of said inside face of the last ply and of the corresponding part of outside face of said film, comprising or not a layer of said low temperature heat-sealing product.
This improvement may consist in forming a last waterproof fold. This modality is intended to increase, when this is made necessary in particular by local climatic conditions, the sealing of the packaging formed, the sealing of beaches (20, 21) ensuring only that the packaging formed is not likely to unfold.
Typically, said inner layer can be identified, so as to be correctly positioned on the part of the film forming said last ply.

Thus, said internal heat-sealing layer typically comprises commercial products, typically in the form of coatings based on acrylic products, PVDC, heat-sealing varnish, in the form of a flat or marked coating, said internal layer being able to adhere to said product. low temperature heat sealing deposited on said outer face.
Said internal layer does not stick, when cold, to said low-temperature heat-sealing product, so that there is no sticking between turns of the film on reel.
However, it is also possible according to the invention, to have said internal layer identified and positioned on the central strip of said film - strip 8 mm in width in FIG. 1, so as not to be able to be opposite the tracks identified (20,21) of said low temperature heat seal product.

In the film according to the invention, said marking of said layer of said low-temperature heat-sealing product can be chosen as a function of said folding, so that, during said folding, all or part of a marked range (201,211) is bringing into contact, respectively, of all or part of another marked area (202,212) or possibly of the inner face of the film, said inner face being, by itself or thanks to said inner layer, suitable for sealing with said product heat sealing, so that, after folding said block, there remains no low temperature heat sealing product which is outside the package.
In the case of the example represented by FIG. 1, the identified areas (20,21) are made up of half-areas (201,202,211,212) which are compared by folding around fold lines (203,213). Thus, in this case, not only does said heat-seal product not appear on the outside of the packaging, but also there is no longer any free surface covered with a layer of said heat-seal product, which is advantageous in terms of packaging security, the risk of accidental contact between said heat-sealing product and the food product being thus impossible.

According to the invention, said polyolefin-based film is preferably chosen from PP, OPP, metallized OPP, multilayer OPP-based films, coated OPP films, expanded OPP to pearlescent appearance and HDPE.
As already mentioned, these films or the films according to the invention can comprise a barrier layer, typically an oxygen barrier, typically chosen from EVOH or PVDC.

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, typically cubic or parallelepipedic.

EXAMPLE OF IMPLEMENTATION

We made a film of which a portion (1) is shown in Figure 1
A 38 µm thick OPP film was used

On its outer face, a weight of 3 g / m ² of a commercial low-temperature heat-sealing varnish (varnish based on d) was deposited, in a marked manner and according to the ranges (20, 21) of FIG. 1 EVA).

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 faces have broken, to return to its shape initial plane.

BENEFITS

The films according to the invention constitute a solution to all of the problems raised previously mentioned.
In addition, these films have been found to have very good machinability - or ease of use on an industrial packaging line, in particular it has been observed that, no doubt thanks to the choice of said low-temperature heat-sealing product, said film does not had no tendency to adhere to the said folding boxes as could happen with other films tested by the applicant.

Claims (6)

1. Packaging film for rigid or semi-rigid blocks composed of sides formed by folding and sealing portions of the said film, characterised in that:

   a) it includes a polyolefin-based film,

   b) the outside face of the said film comprises an external layer of a low temperature heat sealing product forming marked areas so that when the said heat sealing has been done after the said folding, the said packaging obtained has sides that are fixed and stable, the said heat sealing product performing a heat sealing function activated at a temperature varying from 60°C to 110°C.
2. Film according to claim 1, in which at least part of the inside face of the last fold of the said folding comprises an internal layer of a heat sealing product, so as to improve closing of the last fold by final sealing of the said inside face of the last fold and the corresponding part of the outside face of the said film, possibly but not necessarily comprising a layer of the said heat sealing product.
3. Film according to either claim 1 or 2, in which the said polyolefin-based film is chosen from among PP, OPP, metallised OPP, multilayer films based on OPP, coated OPP films, expanded nacreous OPPs and HDPEs.
4. Film according to claim 3, comprising an oxygen barrier layer chosen typically from among EVOH and PVDC.
5. Use of a film according to any one of claims 1 to 4 for packaging of food products in the form of rigid or semi-rigid blocks, typically cubic or parallelepiped-shaped blocks.
6. Use of a film according to claim 5, in which the said marking of the said layer of the said low temperature heat sealing product is chosen as a function of the said folding pattern, so that when the said folding is done, all or part of the marked area is in contact, respectively, with all or part of another marked area, or possibly the inside face of the film, the said inside face being suitable for sealing with the said heat sealing product either by itself or due to the said internal layer, such that there is no low temperature heat sealing product remaining outside the packaging after the said block has been folded.

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