EP0135431B1 - Manufacturing process for container lids to be opened by peeling, and lids obtained by the realisation of this method - Google Patents

Abstract

A process for manufacturing covers intended to close containers which are opened by peeling off the cover, these covers being of a type comprising an orifice and two closure elements disposed on each side of the orifice which they close and in which they adhere to one another, characterized in that it consists: in forming a series of holes (3) intended to form the orifices of the covers in a strip (2); in applying to one of the faces of the perforated strip (2) a first continuous coating (4) intended to form one of the two closure elements, this first coating being separable at least partially from the strip (2) by peeling off; in applying to the other face of the perforated strip (2) a second continuous coating (5) so that it comes into contact with the parts of the first coating (4) which are defined by the holes (3) and adheres strongly to these parts as well as to the perforated strip (2), this second coating (5) being intended to form the other closure element; and in cutting out the multi-layer sheet (1) thus formed so that the holes (3) are all situated in a cover (7).

Description

The present invention relates to a method of manufacturing lids intended for closing receptacles with peeling openings, these lids being of the type comprising an orifice and two closing elements arranged on either side of the orifice which they seal and in which they adhere to each other.

Lids of this type (see for example US-A-4372460) have been developed to close containers containing food products such as drinks or yogurt. Those currently found on the market are not entirely satisfactory, however. The installation of their closing elements indeed requires a lot of time and leads to relatively high manufacturing costs. Furthermore, their internal closing element, that is to say the one which is intended to be on the side of the product to be packaged, is clearly smaller than the inlet of the container and does not always perfectly fulfill its function of sealing. In addition, it is often difficult to position over the opening.

• - à réaliser dans une bande une série de trous destinés à constituer les orifices des opercules;
• - à appliquer sur l'une des faces de la bande perforée un premier revêtement continu destiné à constituer l'un des deux éléments de fermeture, ce premier revêtement étant susceptible d'être séparé au moins partiellement de la bande par pelage;
• - à appliquer sur l'autre face de la bande perforée un second revêtement continu de manière à ce qu'il vienne en contact avec les parties du premier revêtement qui sont délimitées par les trous et adhère fortement à ces parties ainsi qu'à la bande perforée, ce second revêtement étant destiné à constituer l'autre élément de fermeture; et
• - à découper la nappe multicouche ainsi formée de telle sorte que les trous soient tous situés dans un opercule.

The present invention proposes to remedy these drawbacks and, to do this, it relates to a process for manufacturing lids intended to close containers with opening by peeling, this process being characterized in that it consists:

• - To produce in a strip a series of holes intended to constitute the orifices of the lids;
• to apply to one of the faces of the perforated strip a first continuous coating intended to constitute one of the two closing elements, this first coating being capable of being at least partially separated from the strip by peeling;
• - applying a second continuous coating to the other side of the perforated strip so that it comes into contact with the parts of the first coating which are delimited by the holes and strongly adheres to these parts as well as to the strip perforated, this second covering being intended to constitute the other closing element; and
• - Cutting the multi-layer sheet thus formed so that the holes are all located in a cover.

The manufacturing of the lids can thus be entirely mechanized, which makes it possible to accelerate the production rates and consequently to lower the cost price of these lids. In addition, as the first and second coatings completely cover the two faces of the lids, the containers can be closed in a perfectly sealed manner and the quality of the packaged product therefore does not risk spreading over time.

When at least one of the first and second coatings is called upon to constitute one of the faces of the multilayer ply, it may be advantageous to apply it by extrusion-lamination, laminating or paraffinizing.

On the other hand, when it is desirable for the multilayer ply to have more than three layers, at least one of the first and second coatings can be applied by sandwich extrusion between the perforated strip and an additional strip.

Advantageously, opening primers are produced between the perforated strip and the first coating, in areas located on the cutting lines of the multilayer ply.

Thanks to these opening primers, the consumer has a better grip on the first coating and will therefore be able to separate it more easily from the perforated strip. During this operation, the part of the second coating which is integral with the first coating will of course be torn off with the latter, which will then allow the consumer to have access to the contents of the container.

According to a particular embodiment of the method according to the invention, the opening primers can be produced by creating zones of non-adhesion on the strip, prior to the application of the first coating, for example by application of '' a varnish based on polysiloxane or polyamide or nitrocellulose ink, on rotogravure or flexo printer.

According to another particular embodiment of this process, the opening primers can also be produced by carrying out additional perforations in the strip, prior to the application of the first and second coatings.

In the case where the second coating is covered by an additional strip, it may be desirable for this to be separable by peeling. Indeed, as an interface between the additional strip and the second coating is generally sterile, it will suffice to provide a sterile enclosure and to carry out therein the peeling of the additional strip, the filling of the containers, and the sealing of the lids (of so that the second coating is turned towards the containers) to condition a product in a perfectly aseptic manner.

• - la figure 1 est une vue en pespective schématique montrant une bobine formée par l'enroulement d'une nappe multicouche obtenue lors de la mise en œuvre du procédé conforme à l'invention, ainsi qu'un tronçon d'une autre nappe multicouche légèrement différente de la précédente;
• - la figure 2 est une vue schématique d'une machine réalisant l'extrusion-lamination d'un revêtement sur une bande perforée;
• - la figure 3 est une vue analogue à la figure 2, mais montrant la machine réalisant l'extrusion-lamination d'un autre revêtement sur l'autre face de la bande;
• - la figure 4 est une vue en coupe à échelle agrandie de la nappe multicouche visible sur la figure 3;
• - la figure 5 est une vue schématique d'une machine réalisant l'extrusion-sandwich d'un revêtement entre une bande perforée et une bande supplémentaire;
• - la figure 6 est une vue schématique d'une machine permettant de contre-coller une bande supplémentaire sur l'une des faces d'une bande perforée;
• - la figure 7 est une vue schématique d'une machine permettant de fixer par paraffinage une bande supplémentaire sur chacune des faces d'une bande perforée;
• - la figure 8 est une vue en perspective montrant un récipient obturé par un opercule obtenu par la mise en oeuvre du procédé conforme à l'invention;
• - la figure 9 est une vue en perspective du récipient visible sur la figure 8, mais pendant l'ouverture de celui-ci; et
• - la figure 10 est une vue en perspective d'un récipient obturé par un autre opercule obtenu par la mise en oeuvre du procédé selon l'invention.

Other characteristics and advantages of the present invention will emerge from the description which will be given below by way of nonlimiting example with reference to the appended drawings in which:

• - Figure 1 is a schematic perspective view showing a coil formed by the winding of a multilayer ply obtained during the implementation of the method according to the invention, and a section of another multilayer ply slightly different from the previous one;
• - Figure 2 is a schematic view of a machine performing the extrusion-lamination of a coating on a perforated strip;
• - Figure 3 is a view similar to Figure 2, but showing the machine performing the extrusion-lamination of another coating on the other side of the strip;
• - Figure 4 is a sectional view on an enlarged scale of the multilayer web visible in Figure 3;
• - Figure 5 is a schematic view of a machine performing the sandwich extrusion of a coating between a perforated strip and an additional strip;
• - Figure 6 is a schematic view of a machine for laminating an upper strip plementary on one side of a perforated strip;
• - Figure 7 is a schematic view of a machine for fixing by waxing an additional strip on each side of a perforated strip;
• - Figure 8 is a perspective view showing a container closed by a cover obtained by the implementation of the method according to the invention;
• - Figure 9 is a perspective view of the container visible in Figure 8, but during the opening thereof; and
• - Figure 10 is a perspective view of a container closed by another seal obtained by the implementation of the method according to the invention.

The multilayer ply 1 which is shown on the left in FIG. 1 is in the form of a coil making it possible to produce it with a length of several hundred linear meters.

In the embodiment illustrated in FIG. 1, the ply consists of three layers, namely an intermediate strip 2 pierced with holes 3 judiciously spaced from each other, and two coatings 4,5 applied to the upper and lower faces of the intermediate strip, these two coverings closing the holes 3 in which they strongly adhere to one another.

In certain cases, the ply 1 could comprise more than three layers, the coatings 4 and 5 possibly being covered in turn by a coating with one or more layers.

The intermediate strip 2 can have a thickness of the order of 15 to 200 microns (1.5 to 20-10 µm) and be made of metal, in particular aluminum or aluminum alloy, of a cellulosic material such as paper, or a synthetic material such as polyvinyl chloride, polyester, polypropylene, polyethylene, polyamide, polybutylene, etc.

The coatings 4, 5 can have a thickness of the order of 10 to 100 microns (1 to 10 × 10 -5 m) and be made of a synthetic material such as polyester, polypropylene, polyethylene, polybutylene, a polyamide, an ethylene-acrylic acid copolymer, an ionomer resin, etc.

The coating 4, that is to say that which is fixed on the upper face of the intermediate strip 2 is made of a material which has little affinity for the latter so as to be able to be separated therefrom relatively easily by peeling. On the contrary, the covering 5 is made of a material which has a great affinity for the intermediate strip and the covering 4, so that it cannot be separated from the latter.

It will be noted here that when the coatings 4 and 5 are themselves coated with an additional coating, the latter is preferably constituted by an aluminum strip optionally coated on its external face with a layer of polyester, polypropylene, polyethylene , polybutylene, polyamide, ethylene-acrylic acid copolymer, ionomer resin, iron-on varnish, etc.

The multilayer ply 1 is intended to be cut along the closed lines 6 corresponding to the outline of the lids 7 to be produced. The location of these lines, as well as that of the holes 3 of the intermediate strip 2, are of course chosen so that each cover has a hole 3 and that the cutting falls are as small as possible.

It will be noted here that the ply 1 comprises, between the intermediate strip 2 and the coating 4, non-adhesion zones 8 adjacent to one of the sides of the lids 7. These zones are in fact provided to allow the consumer wishing to open a container closed by a cover 7 to more easily grasp the coating 4 in order to remove it without difficulty by peeling.

Referring now to the section of ply 1 represented on the right in FIG. 1, it will be noted that the non-adhesion zones 8 have been replaced by tongues 9 located no longer inside, but outside of the lids . These tabs, which also have the purpose of facilitating the peeling of the coating 4, are produced by drilling a second series of holes in the intermediate strip 2, the coatings 4 and 5 further sealing off these other holes by adhering to them one with the other.

We will now describe several techniques for applying one or more coatings on a perforated strip such as the intermediate strip 2 of the plies 1 and 1 a.

By first referring to FIG. 2 which illustrates the technique of extrusion-lamination, it can be seen that the intermediate strip 2 circulates between two rotary cylinders 10, 11 while a die 12 of conventional design delivers a viscous film 13 in the slot formed between the upper face of the strip 2 and the downstream cylinder 11. The film 13, which consists of a molten material intended to form the coating 4, is slightly pushed back into the holes 3 (and where appropriate in the holes corresponding to the tongues 9) of the strip 2 during its passage between the two cylinders, then cooled between two suitable cylinders not shown.

It will be noted here that the non-adhesion zones 8 can be produced on the intermediate strip by printing a varnish or an ink on a gravure or flexo printer, prior to the application of the film 13.

When the coating 4 is deposited over the entire length of the intermediate strip, the latter is then turned over and put back into circulation between the cylinders 10 and 11, as shown in FIG. 3. The die 12, which now contains the one of the materials used for producing the coating 5, delivers a viscous film 14 in the slot formed between the face of the strip 2 which is still exposed and the cylinder 11.

The film 14 is in turn slightly pushed back into the holes 3 (and the holes 9 when these exist) during its passage between the cylinders 10, 11, which allows it to come into contact with the coating 4 and strongly adhere to the latter, after which it solidifies between the above mentioned cooling cylinders.

The coatings 4 and 5 could of course be applied with the same machine equipped with two dies. Furthermore, to increase the adhesion between one of the coatings and the strip 2, for example at the periphery of the holes 3 (and 9 if these exist), the corresponding face of the strip may be coated with a promoter d adhesion applied by a helio element integrated on the extruder, or treating said face by effluvage, in particular by Corona discharge.

Referring now to FIG. 5 which illustrates the sandwich extrusion technique, it can be seen that the strip 2 and an additional strip 15 circulate between two rotary cylinders 16, 17, while a die 18 delivers a viscous film 19 in the slot made between the two strips 2 and 15. The film 19, which consists of a molten material which may be one of those used to produce the coating 5, is slightly pushed back into the holes 3 of the strip 2, then cooled in a manner known per se.

The material constituting the film 19 could have a great affinity for the strip 2 and little affinity for the additional strip 15. In this case, the additional strip could in fact be separated by peeling from the strip 2, which would make it possible to put bare a sterile surface.

Referring moreover to FIG. 6, which illustrates the technique of lamination, it can be seen that the perforated strip 2 and a strip 20, preferably made of aluminum, circulate between two rotary cylinders 21, 22. Before reaching the cylinder 21, the sheet 20 circulates between a cylinder 23 immersed in an adhesive bath 24 and a pressure cylinder 25.

The strip 20 is slightly pushed back into the holes 3 during its passage between the cylinders 21, 22 and adheres perfectly to the strip 2 at the outlet of an appropriate dryer (not shown) making it possible to evaporate the water contained in the glue .

To fix a second metal strip on the other face of the strip 2, one could also use the installation shown in FIG. 6. One could however use an installation allowing the second metal strip to be bonded with a reactive adhesive. with at least two components, this installation then comprising driers to evaporate the solvents and heating cylinders to reactivate the adhesive. One could also use an installation allowing the use of glues without solvents.

Referring now to FIG. 7, which illustrates the waxing technique, it can be seen that the perforated strip 2 circulates in a bath of wax 26 or “hot-melt” in the molten state, before being sandwiched between two bands 27, 28, metallic or not, flowing between two rotary cylinders 29, 30. At the exit of the latter, the bands 27 and 28 adhere to each other in the holes 3 (and the holes 9 when these exist) while a cooling cylinder (not shown) is provided to harden and solidify the wax or hot-melt.

FIG. 7 shows an installation making it possible to fix the two strips 27, 28 simultaneously on the strip 2. It goes without saying, however, that only one of the two strips 27 and 28 could be fixed by waxing.

• - on réalise dans la bande 2, au moyen d'une presse ou d'un outil de découpe rotatif, les trous 3 destinés à former les orifices des opercules 7, et les trous 9 lorsque ceux-ci sont nécessaires;
• - on ménage les zones de non-adhérence en imprimant un vernis ou une encre sur l'une des faces de la bande perforée 2, à l'aide d'une imprimeuse hélio ou flexo. Dans le cas où le revêtement 4 serait transparent, l'imprimeuse pourrait également être utilisée pour réaliser des impressions décoratives ou publicitaires telles que celles représentées en 31 sur les figures 8 et 9; et
• - on applique les revêtements 4, 5 sur deux faces de la bande perforée:
• . par extrusion-lamination, comme représenté sur les figures 2 et 3;
• . par extrusion-sandwich, comme représenté sur la figure 5; ou
• . par contre-collage, comme représenté sur la figure 6; ou
• - par paraffinage, comme représenté sur la figure 7.

To make the multilayer plies 1 shown in FIG. 1, the procedure is as follows:

• - In the strip 2, the holes 3 intended to form the orifices of the lids 7, and the holes 9 when these are necessary are produced in the strip 2, by means of a press or a rotary cutting tool;
• - The areas of non-adhesion are cleaned by printing a varnish or an ink on one of the faces of the perforated strip 2, using a gravure or flexo printer. In the case where the coating 4 is transparent, the printer could also be used to make decorative or advertising prints such as those shown at 31 in Figures 8 and 9; and
• - the coatings 4, 5 are applied to two faces of the perforated strip:
• . by extrusion-lamination, as shown in Figures 2 and 3;
• . by sandwich extrusion, as shown in Figure 5; or
• . by lamination, as shown in Figure 6; or
• - by waxing, as shown in FIG. 7.

The technique used to apply the coating 4 could of course be different from that used to apply the coating 5.

The multi-layer tablecloths 1 are supplied on a reel to manufacturers processing products such as drinks or yoghurts.

To package these products, these manufacturers manufacture containers of the type of those shown at 32 in FIGS. 8 to 10, generally by thermoforming a strip of plastic material, then fill the containers 32 with the product, fix the multilayer sheet 1 or 1 a (with the coating 4 turned upwards) by heat-sealing, crimping or ultrasonic welding along the entry of the containers, and cut the sheet 1 or 1 a along the lines 6 visible in the figure 1, which correspond to the outer contour of the opening of the containers (and that of the tongues 9 in the case of the ply 1 a).

To open a container such as that shown in FIG. 8, the operator slightly lifts the part of the coating 4 which overhangs the non-adhesion zone 8, grasps this part and pulls it upwards until the part of the covering 5 located in hole 3 is torn off as shown in FIG. 9.

In all of the above, it has been assumed that the coating 4 is entirely peelable. It goes without saying, however, that an adhesion promoter could be applied to the strip 2 by gravure or flexo printing, prior to the application of the coating 4, in order to prevent it from separating from the strip 2 when the hole 3 is completely uncovered.

It will also be specified that the layers 1 or 1 a could be brought for a few minutes to a temperature above 100 ° C. in order to make sterile and allow the packaging of products under perfectly aseptic conditions.

Finally, now referring to FIG. 10, it can be seen that the part of the ply 1, which corresponds to one of the holes 9 in the strip 2, constitutes a gripping tab which the consumer can easily grasp to separate the coating. 4 of the strip 2 and tear off the part of the covering 5 located in the hole 3.

It goes without saying that the present invention also relates to the lids obtained by the implementation of the method described above, as well as the containers closed by such lids.

Claims (15)

1. A process for manufacturing covers intended to close containers which are opened by peeling off the cover, such covers being of the type comprising an orifice and two closure elements disposed on both sides of the orifice which they close and in which they adhere to each other, characterized in that it comprises the steps of:

- forming a series of holes (3) intended to form the orifices of the covers in a strip (2);

- applying to one of the faces of the perforated strip (2) a first continuous coating (4) intended to form one of the two closure elements, such first coating being separable at least partially from the strip (2) by peeling off said coating;

- applying to other face of the perforated strip (2) a second continuous coating (5) so that it comes into contact with the portions of the first coating (4) which are delimited by the holes (3) and firmly adheres to said portions as well as to the perforated strip (2), such second coating (5) being intended to form the other closure element; and

- cutting out the multi-layer sheet (1) thus formed so that the holes (3) are all situated in a cover (7).

2. The process according to claim 1, characterized in that at least one of the first and second coatings (4,5) is applied to the perforated strip (2) by extrusion-lamination, counter bonding or par- affing.

3. The process according to claim 1, characterized in that at least one of the first and second coatings (4, 5) is applied by extrusion-sandwiching between the perforated strip (2) and an additional strip (15; 20; 27, 28).

4. The process according to any one of the claims 1 to 3, characterized in that opening tabs (8, 9) are formed between the perforated strip (2) and the first coating (4), in zones situated on the cut out lines (6) of the multi-layer sheet (1).

5. The process according to claim 4, characterized in that the opening tabs are formed by creating non adherence zones (8) on the strip (2), before application of the first coating (4).

6. The process according to claim 5, characterized in that the non adherence zones (8) are created by application of a varnish or an ink in a helio or flexo printer.

7. The process according to claim 4, characterized in that the opening tabs are formed by making additional perforations (9) in the strip (2), before application of the first and second coatings (4,5).

8. The process according to any one of the preceding claims, characterized in that the strip (2) has a thickness of the order of 15 to 200 microns (1.5 to 20·10^-5 m) and is made from aluminium, aluminium alloy, polyvinylchloride, polyester, polypropylene, polyethylene, polybutylene, polyamide or paper.

9. The process according to any one of the preceding claims, characterized in that the first and second coatings (4, 5) have a thickness of the order of 10 to 100 microns (1 to 10·10^-5 m) and are made from polyester, polypropylene, polyethylene, polybutylene, polyamide, ethylene-acrylic acid copolymer, or ionomer resin.

10. The process according to claim 3 and any one of claims 4 to 9, characterized in that the additional strip (15; 20; 28, 29) is made from aluminium and is coated on its external face with a layer of polyester, polypropylene, polyethylene, polybutylene, polyamide, ethylene-acrylic acid copolymer, ionomer resin or a heat-bonding varnish.

11. The process according to any one of claims 3 and 10, characterized in that the additional strip (15; 20; 28, 29) is separable by peeling it off.

12. The process according to claim 11, characterized in that the additional strip (15; 20; 28, 29) is separated in a sterile enclosure, before the covers (7) are fixed to the containers (32).

13. The process according to any one of the preceding claims, characterized in that prints (31 ) are formed on the perforated strip (2), before the first coating (4) is applied when the latter is transparent.

14. Covers obtained by the process according to any one of the preceding claims.

15. A container opened by peeling off the cover, closed by a cover according to claim 14.

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