EP2465790A1 - Heat-sealable membrane seal with tab, and method for manufacturing said membrane seal - Google Patents

Abstract

The seal (1) has an upper element possessing constant thickness, and a lower element positioned opposite to the upper element. The lower element comprises a reinforcing film (5) and a heat-sealing film (6) applied on a lip of a container, in a direction of the lip. The upper element and the lower element are associated with each other by a permanent adhesive (7) i.e. thermoplastic polymer, to form a free tab arranged in the upper element. A conductive sheet (3) is positioned in the upper element. An independent claim is also included for a method for fabricating a heat-sealable membrane seal for closing a container.

Description

The invention relates to a cover having a tongue, intended to be used for sealing containers by heat sealing. It also relates to the method of manufacturing said lid.

The fields of use of the cap of the present invention relate in particular, and without limitation, the packaging of products and liquids in the food, chemical, or pharmaceutical industries.

The seals ensuring the closure and the sealing of the containers comprise at least one seal, possibly associated with a support.

When the lid is used alone, it is applied directly to the rim of the container and is secured by induction heat sealing, once the lid is in place. The consumer, when removing the lid of the container at the time of the first opening, then only has to remove the lid by tearing. If the lid makes it possible to guarantee the tightness of the container before first opening, it is not so even if the user decides to leave in place said lid.

The problem of secondary sealing is solved when the cover is combined with a support. In this case, there are two hypotheses.

Either the cover and the support are secured to one another until the first opening. In this case, there is separation of the support and the lid at the latest at the time of opening so that the support remains stuck in the bottom of the plug once the seal removed. It is the support then in contact with the rim which ensures the secondary seal after reclosing of the lid. This type of seal is reserved for certain limited markets because it remains expensive to produce.

Either the lid and the support are placed in the stopper and the rim independently. More specifically, the support is put in place at the bottom of the cap and held in position by a peripheral lug. The seal is positioned on the rim and sealed, usually by induction heat sealing, once the cap is closed. Therefore, at the time of opening, the support remains stuck at the bottom the cap, and the consumer removes the lid. Again, it is the support then in contact with the rim which ensures the secondary seal after reclosing the lid.

The invention relates more particularly to the lids whether they are used alone or in combination with a support.

The covers are made of multilayer complexes. They often have a tongue which is either integrated in the surface of the lid or is a protrusion, which rests on the top of the lid or hangs along the mouth of the container.

The Applicant's invention relates specifically to the lids provided with a tongue integrated in the surface of the lid.

In this case, the tongue is necessarily formed in only part of the thickness of the lid. To the Applicant's knowledge, a seal of this type has been described for the first time in the document US 4,961,986 .

When the lids are made integral with the rim of the container by induction heat sealing, they systematically contain a sheet of conductive material which heats under the effect of an induced current and ensures the transfer of heat to the heat-sealing film in contact with the drink . This implies that the heat-sealing film and the sheet of conductive material are in proximity to one another to facilitate heat transfer. This is the reason why the heat-sealing film is most often associated directly with the sheet of conductive material in the lower element of the lid.

For example, the document US 4,961,986 already mentioned, describes a heat-sealable seal comprising an aluminum membrane in its lower element. The upper element is formed of a polyester film partially associated with the lower element by an adhesive, so as to form the tongue.

The document EP 1789260 B1 discloses a lid comprising a tongue made in part of the thickness of the lid. The metal layer is directly associated with the heat-sealing film in the lower element of the lid.

The document WO 2006/073777 A1 describes a lid similar to that described in the document EP 1789260 B1 but in which a polyester layer is interposed between the heat-sealing film and the sheet of conductive material.

The document US 4,848,931 discloses a lid for containers containing food and whose upper portion comprises a sheet of conductive material. Before heating the contents of the container in a microwave oven, the user separates the upper part and the lower part. The uprooting of the upper part is effected by means of a tongue which is not free and which is formed in the entire thickness of the lid. In order to facilitate their separation, the upper and lower parts of the lid are not integral, they are temporarily bonded by means of a resin of low adhesion strength.

The covers described in the aforementioned prior art prohibit the user to be able to view the contents of the container before the first opening, that is to say without first tearing the lid, because of the presence of the sheet of conductive material between the tongue and the drink. In the particular case of a lid as described in the document US 4,848,931 , the upper part of the operculum must be torn off in order to be able to visualize the contents.

To solve this problem, rather than inserting the conductive sheet in the lower element of the lid, the Applicant had the idea of incorporating it into the upper element, that is to say in the part comprising the tongue. In this way, lifting the tongue at the time of tearing, the user can view the contents of the container. It was not obvious that the presence of the conductive layer in the upper element would ensure satisfactory heat sealing without affecting the bonding of the upper and lower elements of the lid.

• un élément supérieur d'épaisseur constante
• un élément inférieur de même forme et positionné en regard de l'élément supérieur, comprenant en direction du buvant, un film de renfort et un film thermoscellant destiné à être appliqué sur le buvant du récipient.

More specifically, the Applicant has developed a heat-sealable cap for closing a closure container with a stopper or capsule, comprising successively in the direction of the mouth of the container:

• an upper element of constant thickness
• a lower element of the same shape and positioned facing the upper element, comprising in the direction of the rim, a reinforcing film and a heat-sealing film intended to be applied to the rim of the container.

The upper element and the lower element are associated by means of a permanent adhesive, so as to form a free tongue arranged in the upper element.

The adhesive permanently secures the upper and lower elements. The user can tear in a single operation the entire lid, namely the lower and upper elements. The tongue allows to tear the lid without delamination of the latter.

The lid according to the invention is characterized in that it contains at least one sheet of conductive material positioned exclusively in the upper element.

By free tongue is meant a tongue without any bonding, including temporary. It is not related to the lower element of the operculum, including temporarily. It is arranged to be partially contained in the perimeter of the lid. In other words, the upper and lower elements of the lid are not linked over the entire periphery of the lid.

The invention comprises two main embodiments in which the adhesive is either applied over the entire surface of the lower element or the upper element, or is applied on part of their surface.

In the case where the adhesive is applied to the entire surface of the lower element or the upper element, a reinforcing film is applied to the adhesive part opposite the upper or lower element, respectively. thus forming a tongue in the upper element. Thus, the tongue formed in the upper element does not adhere to the lower element of the operculum opposite.

More specifically, when the adhesive is applied to the entire lower face of the upper element, the tongue comprises a reinforcing film applied to the adhesive opposite the lower element of the lid.

On the contrary, when the adhesive is applied over the entire upper face of the lower element, the lower element contains a reinforcing film applied to the portion of the adhesive facing the tongue.

In the embodiment in which the adhesive is applied to only a part of the surface of the upper element or the lower element, said adhesive is applied to the lower face of the upper element or to the upper face of the the lower element facing one another thus forming a tongue in the upper element. In this case, there is no intervening reinforcement film positioned between the upper and lower elements on the part of their surface facing one another.

As already indicated, the lower element of the lid comprises at least two layers, a heat-sealing film and a reinforcing layer or film. In an advantageous embodiment, the reinforcing film and the heat-sealing film are in direct contact through a binding agent. While the heat-sealing film makes it possible to seal the container during induction heat-sealing of the lid on the rim of the container, the reinforcing film makes it possible to tear the heat-sealing film when the container is opened by the first user.

The heat-sealing film is made of a thermoplastic material compatible with the container on which it must be heat-sealed, and preferably made of polyamide (PA), polypropylene (PP), or polyethylene terephthalate (PET).

Advantageously, the reinforcing film and the heat-sealing film are associated by coating, or by means of a binder which may be a two-component adhesive and more particularly an isocyanate-hydroxyl glue, or combined by extrusion lamination of a thermoplastic polymer.

Thus, the lower element of the operculum not comprising a layer of conductive material such as aluminum is advantageously at least partially transparent or translucent.

The upper element of the lid according to the present invention advantageously has the same shape as the lower element. It necessarily comprises at least one sheet of conductive material which heats when it is traversed by an induced electric current and thus heat-seal the lid.

The sheet of conductive material is advantageously aluminum, and has a thickness that can be between 10 and 50 microns.

As already indicated, the lower element and the upper element are associated by an adhesive, or binder, applied on their surface. This adhesive is preferably a thermoplastic polymer having, preferably, affinities with the two substrates to be assembled.

In the lid according to the invention, the tongue is at least formed by the upper element of said lid which comprises at least one sheet of conductive material. The upper element of the lid may further comprise at least one reinforcing film positioned on and / or under the sheet of conductive material of the upper element of the lid and over its entire surface. This reinforcing film is therefore distinguished from the reinforcing film which can be located only under the tongue when the adhesive bonding the lower and upper elements of the cap is applied over the entire lower face of the upper element.

In general, the reinforcing film referred to in the present invention can be advantageously chosen from the group comprising polyester (PET), bi-oriented polypropylene, and bi-oriented polyamide. It is advantageously in bi-oriented PET. Its thickness is advantageously between 4 and 40 microns.

The lid according to the present invention differs mainly from the prior art in that it does not include a sheet of conductive material in its lower element. This makes it possible to distinguish the contents of the container to which the lid has been heat-sealed but also to propose a support with a distinctive character

Thus, the reinforcing film of the lower element of the lid according to the present invention may advantageously have at least one illustration comprising a pattern of distinction, a design, or an anti-counterfeit pattern. It is preferentially the reinforcement film of the lower element, in contact with the heat-sealing film.

Advantageously, the lid according to the present invention has a thickness of between 20 and 600 μm, and more advantageously still between 50 and 300 μm.

The object of the present invention also relates to the method of manufacturing a heat sealable cap as described above. This manufacturing process can take at least two embodiments.

• on prépare la bande inférieure de l'opercule en associant une bande de film de renfort avec une bande de film thermoscellant ;
• on prépare la bande supérieure de l'opercule comprenant au moins une feuille en matériau conducteur ;
• on associe les bandes inférieure et supérieure de l'opercule par application d'un adhésif sur partie seulement de la face inférieure de la bande supérieure ou de la face supérieure de la bande inférieure, de manière à former une bande opercule,
• on découpe sur la totalité de l'épaisseur de la bande opercule, les opercules à la forme souhaitée.

In a first embodiment, the method comprises the following steps:

• the lower band of the lid is prepared by combining a reinforcing film strip with a heat-sealing film strip;
• preparing the upper band of the lid comprising at least one sheet of conductive material;
• the lower and upper bands of the cover are associated by application of an adhesive on only part of the lower face of the upper band or of the upper face of the lower band, so as to form a cap strip,
• the operculas are cut to the desired shape over the entire thickness of the sealing strip.

• on prépare une bande inférieure en associant une bande de film de renfort avec une bande de film thermoscellant ;
• on prépare une bande supérieure comprenant au moins une feuille en matériau conducteur ;
• on applique un adhésif sur la toute face inférieure de la bande supérieure ou sur toute la face supérieure de la bande inférieure;
• on applique une bande de film renfort sur partie de l'adhésif présent soit sur la face inférieure de la bande supérieure, soit sur la face supérieure de la bande inférieure de manière à former une languette dans la bande supérieure après association de la bande inférieure et de la bande supérieure, et après découpage de la bande opercule ;
• on associe la bande inférieure et la bande supérieure de manière à former une bande opercule ;
• on découpe sur la totalité de l'épaisseur de la bande opercule, les opercules à la forme souhaitée.

In a preferred embodiment, the method comprises the following steps:

• a lower strip is prepared by combining a reinforcing film strip with a heat-sealing film strip;
• an upper band is prepared comprising at least one sheet of conductive material;
• an adhesive is applied to the entire lower face of the upper band or over the entire upper face of the lower band;
• a strip of reinforcing film is applied to the part of the adhesive present either on the lower face of the upper band or on the upper face of the lower band so as to form a tongue in the upper band after association of the lower band and the upper band, and after cutting the band seal;
• the lower band and the upper band are associated so as to form a cap strip;
• the operculas are cut to the desired shape over the entire thickness of the sealing strip.

The adhesive may be applied to all or only part of the surface of the lower or upper members, so as to form the tongue. It is advantageously extruded between the upper element and the lower element of the lid.

When the adhesive is applied over the entire surface of the upper element or the lower element, a reinforcing film is applied on part of the adhesive before joining the upper and lower elements. This makes it possible to obtain a tongue free of any bonding on its face facing the lower element of the lid.

A particular embodiment consists in associating the sheet of conductive material of the upper element of the lid with at least one reinforcing film strip. This reinforcing film is advantageously polyester bi-oriented. It is positioned on and / or under the sheet of conductive material of the upper element of the lid and is of the same shape. Moreover, the reinforcing film on the sheet of conductive material may advantageously be printed

• La figure 1 représente un opercule à languette dont l'élément supérieur est formé exclusivement par une feuille en matériau conducteur.
• La figure 2 représente un opercule à languette dont l'élément supérieur est formé par une feuille en matériau conducteur et un film de renfort.
• La figure 3 représente un opercule à languette dans lequel un adhésif est appliqué sur la totalité de la surface de l'élément supérieur.
• La figure 4 représente un opercule à languette dans lequel un adhésif est appliqué sur la totalité de la surface de l'élément supérieur. L'élément supérieur comprend en outre un film de renfort de part et d'autre de la feuille en matériau conducteur.
• La figure 5 représente un opercule à languette dans lequel un adhésif est appliqué sur la totalité de la surface de l'élément inférieur.

The invention and the advantages which result therefrom will emerge more clearly from the following figures given by way of example and in a nonlimiting manner.

• The figure 1 represents a tab seal whose upper element is exclusively formed by a sheet of conductive material.
• The figure 2 represents a tab seal whose upper element is formed by a sheet of conductive material and a reinforcing film.
• The figure 3 represents a tab seal in which an adhesive is applied over the entire surface of the upper member.
• The figure 4 represents a tab seal in which an adhesive is applied over the entire surface of the upper member. The upper element further comprises a reinforcing film on either side of the sheet of conductive material.
• The figure 5 represents a tab seal in which an adhesive is applied over the entire surface of the lower member.

The figure 1 represents a lid (1) according to the invention. This lid is intended to be heat-sealed by induction on the rim of a container. It comprises successively, in the direction of drinking, an upper element (2) and a lower element (4).

The upper element (2) forms the tongue and comprises a sheet of conductive material (3), usually aluminum. On the other hand, the lower element (4) comprises a reinforcing film (5), preferably bi-oriented polyester, and a heat-sealing film (6).

The upper (2) and lower (4) elements are associated with the aid of an adhesive (7) applied on only part of their facing surface. This partial association makes it possible to form the free tongue of the operculum (1).

Since the lower element does not comprise a sheet of conductive material, the zone (9) is advantageously at least partially transparent or translucent. In a particular embodiment, this zone (9) comprises illustrations.

The operculum represented on the figure 2 includes the same characteristics as those of the operculum of the figure 1 . It represents a particular embodiment in which, the upper element (2) of the lid further comprises a reinforcing film (8) associated with the sheet of conductive material (3). On the figure 2 , said reinforcing film (8) is positioned on the sheet of conductive material of the upper element of the lid. It may however be positioned on and / or under the sheet of conductive material (3) of the upper element (2) of the lid (1).

• formation de l'élément inférieur de l'opercule par association d'une bande de film de renfort avec une bande de film thermoscellant ;
• formation de l'élément supérieur de l'opercule comprenant au moins une feuille en matériau conducteur ;
• association de l'élément inférieur et de l'élément supérieur de l'opercule par application d'un adhésif, sur partie seulement de leur surface, de manière à former une bande opercule ;
• découpe des opercules sur la totalité de l'épaisseur de la bande opercule.

The heat-sealable seal shown on the figure 1 or 2 can be manufactured according to the following steps:

• forming the lower element of the seal by joining a reinforcing film strip with a heat-sealing film strip;
• forming the upper element of the lid comprising at least one sheet of conductive material;
• combination of the lower element and the upper element of the seal by applying an adhesive, only on part of their surface, so as to form a seal strip;
• cutting of the covers over the entire thickness of the sealing strip.

The tab seal shown on the figure 3 comprises an upper element comprising a sheet of conductive material (3). An adhesive (7) covers the entire surface of the underside of this sheet of conductive material (3). In addition, a reinforcing film (10) is applied to only part of the adhesive (7). This interlayer reinforcing film prevents bonding between at least a portion of the upper and lower elements. Thus, the tongue (7) is free of any bonding, and is arranged in part of the periphery of the upper element. In addition, this cover comprises a lower element comprising a reinforcing film (5) and a heat-sealing film (6).

The upper element of the lid has a constant thickness, the interlayer reinforcing film being applied to the adhesive covering the underside of the tongue.

A particular embodiment of this operculum is illustrated on the figure 4 . It further comprises a reinforcing film (8) on either side of the sheet of conductive material (3).

• formation de l'élément inférieur de l'opercule par association d'une bande de film de renfort avec une bande de film thermoscellant ;
• formation de l'élément supérieur de l'opercule comprenant au moins une feuille en matériau conducteur, et éventuellement au moins un film de renfort positionné sur et/ou sous la feuille en matériau conducteur ;
• application d'un adhésif sur la totalité de la surface inférieure de l'élément supérieur, ladite surface étant en regard de l'élément inférieur de l'opercule ;
• application d'un film de renfort (10) sur partie de l'adhésif (7), de manière à empêcher le collage de la languette sur l'élément inférieur ;
• association des éléments supérieur et inférieur ;
• découpe des opercules sur la totalité de l'épaisseur de la bande opercule.

Such lids ( Figures 3 and 4 ) are manufactured according to a process comprising in particular the following steps:

• forming the lower element of the seal by joining a reinforcing film strip with a heat-sealing film strip;
• forming the upper element of the lid comprising at least one sheet of conductive material, and optionally at least one reinforcing film positioned on and / or under the sheet of conductive material;
• applying an adhesive to the entire lower surface of the upper element, said surface facing the lower element of the lid;
• applying a reinforcing film (10) on part of the adhesive (7), so as to prevent sticking of the tongue on the lower element;
• association of the upper and lower elements;
• cutting of the covers over the entire thickness of the sealing strip.

On the figure 5 , a tab seal in which an adhesive (7) has been applied to the entire surface of the lower member is shown. On the other hand, a reinforcing film (10) is applied on only part of the adhesive (7), so as to prevent the upper and lower elements from sticking to their entire surface.

The invention and its advantages are apparent from the foregoing. In particular, the development of a heat-sealable lid whose structure makes it possible to visualize the contents of the container before first opening.

Claims (10)

Heat-sealable seal (1) for closing a closure container with a stopper or capsule, comprising successively in the direction of the mouth of the container: an upper element (2) of constant thickness, - a lower element (4) of the same shape and positioned opposite the upper element, comprising in the direction of the rim, a reinforcing film (5) and a heat-sealing film (6) intended to be applied to the rim of the container;
the upper and lower elements being associated by means of a permanent adhesive (7) so as to form a free tongue arranged in the upper element, characterized in that it contains at least one sheet of conductive material (3) positioned exclusively in the upper element. Seal according to claim 1, characterized in that the adhesive (7) is applied over the entire lower face of the upper element (2) and in that the tongue comprises a reinforcing film (10) applied on the adhesive facing the lower element. Seal according to claim 1, characterized in that the adhesive (7) is applied to the entire upper face of the lower element (4) and in that the lower element contains a reinforcing film (10) applied on the part of the adhesive next to the tongue. Seal according to Claim 1, characterized in that the adhesive is applied to only a part of the lower face of the upper element or of the upper face of the lower element, the two parts facing each other. 'other. Seal according to claim 1, characterized in that the upper element further comprises at least one reinforcing film positioned on and / or under the sheet of conductive material and over its entire surface. Seal according to claim 1, characterized in that the sheet of conductive material is aluminum and has a thickness of between 10 and 50 microns. Seal according to one of the preceding claims, characterized in that the reinforcing film is chosen from the group comprising polyester (PET), bi-oriented polypropylene, and bi-oriented polyamide and in that its thickness is between 4 and 40 μm. Seal according to claim 1, characterized in that the adhesive is a thermoplastic polymer A method of manufacturing a heat-sealable seal (1) for sealing a closure container with a stopper or capsule, comprising the steps of: a lower strip is prepared by combining a reinforcing film strip with a heat-sealing film strip; an upper band is prepared comprising at least one sheet of conductive material; an adhesive is applied to the entire lower face of the upper band or to the entire upper face of the lower band; a strip of reinforcing film is applied to part of the adhesive present either on the lower face of the upper band or on the upper face of the lower band so as to form a tongue in the upper band after association of the lower band; and the upper band, and after cutting the sealing strip; the lower band and the upper band are associated so as to form a cap strip; the covers are cut to the desired shape over the entire thickness of the seal strip. A method according to claim 9 characterized in that the sheet of conductive material (3) is associated with at least one reinforcing film strip (8) on and / or under said sheet of conductive material.

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