EP0488985A1 - Multilayered foil-cover - Google Patents

Abstract

The invention relates to a multilayered foil-cover consisting, in order, accessorily, of a disc of compressible material (4'), a metal disc (6') optionally covered with a protection disc at synthetic material when the metal disc has to be protected against the aggressivity of the contents of the container, a disc such as a paper disc (8) for example, capable of absorbing a temporary adhesive layer (5') and a disc of synthetic material (7') temporarily connected to the said temporary adhesive layer which is caused to become detached during the process of heating by induction or conduction, said process giving rise to the adhesion of the disc of synthetic material to the neck of the container. <IMAGE>

Description

The present invention relates to a multilayer seal intended to close the neck of a container, and which generally comprises, in order, incidentally a disc of compressible material such as, among other things, reconstituted cork, cardboard, a material plastic or a material having similar properties and a layer of a temporary adhesive, in any event, at least one metallic disc such as an aluminum disc and a polymer disc, the metallic disc, previously secured to a polymer disc being intended to be welded to the neck of the container during an induction or conduction process to which the cover is subjected in contact with the container.

The recycling of plastic or glass containers or cans is becoming a generally recognized necessity. A percentage of the mass to be recycled consists of bottles or containers whose necks were originally closed with a metal disc necessary for the induction or conduction process, generally aluminum.

The number of intermediate layers is optional and depends on user requirements. In any event, the metal disc which will always be referred to below as an aluminum disc is brought to a sufficient temperature, either by induction or by conduction, so that it adheres to the neck of the container. At the same time as the polymer disc protects the aluminum from any contact with the contents of the container and ensures the welding.

When the user has cut the aluminum disc, there remains, on the periphery of the neck of the container, a circle or aluminum debris adhering thereto.

The presence of this metal in the mass to be recycled poses a problem which is sufficiently important for the envisaged recycling cannot be done under economically acceptable conditions.

The object of the invention is to propose a multilayer cover which offers a solution to the problem as it was exposed in the preamble while ensuring a primary inviolability and sealing.

US Patent 4,596,338 has proposed a substantial modification of the conventional order in which the various layers constituting a disc or cover are arranged. However, the suggested order is unacceptable when we cannot tolerate the presence of an air-permeable disc when using a metallic disc, generally aluminum, to ensure total tightness and diffuse heat. required by the induction sealing process.

To achieve this objective in accordance with the invention, the aforementioned cover is constituted, in order, incidentally by a disk of compressible material, a metal disk possibly coated with a protective disk of synthetic material when the metal disk must be protected against the aggressiveness of the contents of the container, a disc such as a paper disc for example, capable of absorbing a layer of temporary adhesive and a polymer disc temporarily connected to said layer of temporary adhesive caused to dissociate during the induction or conduction heating process, which causes the polymer disc to adhere to the neck of the container.

Other details and particularities of the invention will emerge from the description which will be given below of a multilayer cover according to the invention. This description is given by way of example only and does not limit the invention. The reference notations refer to the attached figures in which the thickness of the cover has been exaggerated.

Figure 1 is a sectional view of a stopper provided with a common type seal.

Figure 2 is a sectional view of the neck of a container to which adheres an aluminum disc secured to a polymer disc.

Figure 3 is a sectional view of a plug provided with a cover according to the invention.

Figure 4 is a sectional view of the neck of a container to which adheres only a polymer disc.

To situate once again the problem to which the seal according to the invention offers a new and original solution, reference is made to FIG. 1 in which the neck 1 of a plastic container is noted. It should be clearly understood that if the figures show a container neck 1 provided, for example, with a screw thread and a plug 2 screwing onto it, the invention is in no way limited to this type of closure. It can find application in any type of closure of a bottle or container.

Hitherto the cover of the type shown in Figure 1 included in order, from the top, designated by the reference 3, a disc of reconstituted cork, cardboard or plastic. This disc is hereinafter called "compressible disc" 4. A layer of temporary adhesive, represented by the reference 5, separates the disc of compressible material 4 from an aluminum disc 6 and its purpose is to temporarily bring the disc together aluminum 6 to the compressible disc 4. Finally, the assembly is completed by a polymer disc 7 integral with the aluminum disc 6 and intended to ensure fusion welding during the induction or conduction process and which incidentally protects the aluminum disc of the liquid or powdery products contained in the container.

When the cover and subjected to the induction or conduction process, the aluminum disc heats up to cause the fusion of the layer of adhesive which served as a temporary bond between the aluminum disc 6 and the compressible disc 4. In addition, the heat developed by the phenomenon of induction or conduction causes a local fusion of the edge of the polymer disc 7 which is welded on the neck 1 of the container, integrally with the aluminum disc 6.

We come to the situation represented by Figure 2 where we note that the aluminum disc 6 is welded by its peripheral edge on the neck 1 of the container. This gives rise to the unfavorable situation which has been mentioned above. In fact, when the aluminum disc has been cut by the user during the first use of the container, there remains a crown or scrap of aluminum welded to the periphery of the neck 1 of the container.

It is therefore very clear that all the containers of whatever shape they are, provided that they give rise to the situation illustrated in FIG. 2, cannot be recycled since the mass to be recycled contains metallic elements formed by the aluminum crown welded to the neck of the container.

On the contrary, by making use of composite lids according to the invention, we will find ourselves, after induction or conduction welding, in the situation represented by FIG. 4 where the neck 1 ′ of the container is no longer closed except by a disc. of polymer 7 ′.

To achieve this result, the cover comprises several layers of material which the Applicant expressly says that it can offer certain variants in the spirit of the invention described once again by way of example with particular reference to the figure. 3.

FIG. 3 shows another arrangement of the various layers of the cover thanks to which a result is obtained in a completely original manner which makes it possible to envisage recycling a mass of containers, bottles or waste of the type already described below. above, which does not include any metallic element.

Figure 3 shows indeed the compressible disc 4 ′ to which an aluminum disc 6 ′ adheres. Beyond the aluminum disc 6 ′ is interposed a paper disc 8 or another material capable of absorbing the layer of adhesive 5 ′ which temporarily joins the paper disc 8 to the polymer disc 7 ′.

The heat developed in the aluminum disc 6 ′ during the induction or conduction process melts the layer of temporary adhesive 5 ′ which is absorbed by the paper disc 8. The heat developed in the aluminum disc 6 ′ a caused, in a manner well known per se, the welding of the polymer disc 7 ′ on the neck 1 ′ of the container.

The plug 2 ′ contains the entire aluminum disc 6 ′. On the other hand, after cutting the polymer disc 7 ′, there remains on the neck of the container 1 ′ only a crown of synthetic material and no longer a crown or debris of metal crown as was the case until now .

From the description which has just been given, it will be noted that it is possible to make a sealed closure of a plastic container while incorporating into the multilayer cover the essential metallic sheet, generally of aluminum, and to collect finally a product which does not bear any trace of this metallic sheet. It will be noted, once again, that if the invention has been described with reference to a circular plug intended to be screwed onto the neck of a container, the invention also applies to any container where the seal of a sheet of synthetic material is produced by an induction or conduction process.

Claims (1)

Multilayer seal intended to seal the neck of a container, and which generally comprises, in order, incidentally a disc of compressible material such as, among other things, reconstituted cork, cardboard, a plastic material or a material having similar properties and a layer of a temporary adhesive, in any event at least one metal disc such as an aluminum disc and a polymer disc, the metal disc, previously secured to a polymer disc being intended to be welded to the neck of the container during an induction or conduction process to which the cover is subjected in contact with the container, characterized in that the aforementioned cover consists, in order, incidentally by a disc of compressible material (4 ′), a metallic disc (6 ′) possibly coated with a protective disc of synthetic material when the metallic disc must be protected against the aggressiveness of the contents u of the container, a disc such as a paper disc (5 ′) for example, capable of absorbing a layer of temporary adhesive (8) and a polymer disc (7 ′) temporarily connected to said layer of adhesive temporary (8) caused to separate during the heating process by induction or conduction, process which causes the adhesion of the polymer disc (7 ′) to the neck (1 ′) of the container.

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