Two-part seal with a casein-based lid and casein-based lid

Description

[0001] The invention relates to the technical sector of means for closing a container with a cap or capsule, in particular in the field of dry food products such as freeze-dried coffee, etc., without this being limiting. It relates more specifically to a single seal or a double-piece seal comprising such a seal.

[0002] The sealing of containers with a stopper or capsule, prior to their first opening, can be carried out by means of a double-piece seal or, in certain cases, a simple cover which can be glued or sealed on the rim.

[0003] There are also single-piece seals made of a foamed or non-foamed support. When foam is used, it is made of polypropylene (PP), polyethylene (PE) or polyethylene terephthalate (PET) foams, possibly laminated with PP, PE or polyethylene terephthalate (PET) films. These seals are used to ensure the packaging is sealed, firstly against the contents, whether liquid or not, but also against oxygen, as well as aromas and odors.

[0004] These seals are generally delivered to the capsule or cap manufacturer. The manufacturer inserts them into the bottom of the capsule or cap and delivers them to the end customer. The latter fills the containers (flask, bottle, jar, etc.) which are then sealed using the capsule or cap fitted with its seal. These seals are not intended to be sealed or glued to the rim and are not covered by the invention.

[0005] A double-piece seal consists of a seal placed around the entire edge of the upper rim of the container's neck or mouth, thus insulating the container from the outside, and on the other hand, a generally thicker support, inserted, but not fixed, to the bottom of the cap. Before the container is opened for the first time, the support and the seal can be secured together using a temporary adhesive.

[0006] The role of the lid is first of all to confer tamper-evident protection to the container before the first opening. In addition, it ensures the primary seal against the outside. In addition, it must develop certain compatibility properties with the contents it is supposed to isolate and, for example, be of food quality as soon as the contents themselves are food-grade.

[0007] The support, for its part, is intended to absorb the tolerances between the bottom of the capsule and / or the cap and the upper part of the neck of the container, and in addition, to ensure secondary sealing once the seal has been completely or partially removed. It is therefore capable of ensuring a certain compression with memory effect to allow these tolerances to be absorbed.

[0008] In practice, the seal is inserted into the bottom of the capsule or cap. Once the container is filled, the cap or capsule with the seal is screwed or clipped onto the container. The operculum part of the seal is then in contact with the rim.

[0009] When the container is first opened, the support inserted at the bottom of the cap separates from the seal that remains sealed on the rim. It is only then that the seal is removed by the consumer, the seal, in the closed position of the container, then only being ensured by the support part of the seal pressing against the rim by compression.

[0010] The sealing of the lid on the rim is carried out by gluing or induction heat sealing using a film or heat sealing varnish.

[0011] In the case of gluing, this is traditionally done using a glue compatible with the rim and the underside of the lid. To allow the adsorption of the water contained in the glue, the lid generally contains at least one layer of paper, which requires the presence of an additional element, which impacts the production cost. In addition, and above all, there is always a risk that the glue, which is applied to the rim of the pot, penetrates into the container even though it is a food glue.

[0012] In the case of heat sealing, this is made possible by the combined action of a conductive material, inserted into the thickness of the seal, which, under the effect of electrical induction, heats up, causing the softening of the sealing film or varnish on the rim. The conductive material can be inserted either into the support or into the seal. Most often, it is inserted into the thickness of the seal. In practice, it has a thickness of at least 12 micrometers to ensure heat conduction.

[0013] The heat-sealing film or varnish is made of a polyolefin-type material, chosen from the group including EVA, polyethylene, polypropylene or PET, of the holt melt type or of the terpolymer or ionomer type. Generally speaking, the material constituting the heat-sealing film is chosen according to the nature of the pot. The heat-sealing film can be a single-layer film applied to the underside of the lid by extrusion. It can also be a two-layer film (a lower heat-sealing layer itself and an upper binding layer) applied to the underside of the lid by co-extrusion.

[0014] Documents EP 2 045 194 A1 and WO 2010 / 115811 describe double-piece seals whose cover part incorporates an aluminum foil as a conductive material.

[0015] The disadvantage of the prior art lies mainly in the fact that the layer of conductive material, necessary for heat sealing, complicates the recycling of the lid due to its significant thickness and therefore the quantity of metal required. Indeed, during the recycling process, the conductive material needs to be separated from the other components of the lid and the capsule or cap given their different composition. This therefore involves substantial costs for processing the lids as well as a significant recycling time.

[0016] In some cases, particularly for certain products or markets, the presence of the support is not necessary, so that the seal alone is used. This is particularly the case for so-called "service capsules" for which the presence of a support is incompatible with the shape of the capsule. This is also sometimes the case for developing countries where the price has a strong impact. In these conditions, even if the seal is not optimal, sealing with a simple seal remains sufficient.

[0017] Document EP 2279962 A1 discloses a method for sealing a lid on a glass container. The objective is to improve the tightness of the seal, particularly due to the imperfection of the glass rim, and to improve the sealing strength. To do this, the rim is treated with a casein-based solution before applying a layer of aluminum covered with a sealing film. The proposed solution, while it solves the sealing problem, does not solve the recycling problem.

[0018] Document FR 841 136 A describes a glassine paper intended to seal jam jars, without any provision for covering the glassine paper with a stopper or cap. It is stated that the consumer applies a casein-based layer to the glassine paper by dipping it in milk to ensure that the paper adheres to the rim of the jar.

[0019] The first problem that the invention aims to solve is that of developing a seal or a cover that can be sealed on the rim of a container without requiring heating or glue, which even if they are suitable for food contact within the current legislative framework could be called into question subsequently as the regulations are revised.

[0020] The second problem that the invention aims to solve is to ensure that the capsules, stoppers, seals and lids are recyclable according to a common circuit, that is to say that they can be recycled together, without having to separate the stopper from the lid or the seal and then each of the constituent elements of the lids and seals.

[0021] The third problem that the invention aims to solve is that of proposing seals or covers that are partly biodegradable.

[0022] For this purpose, a seal has been developed for sealing a container closed by a cap or capsule. According to the invention, the seal comprises a casein and / or caseinate-based film intended to be in contact with the rim of said container. The casein and / or caseinate-based film is in the form of an extruded film.

[0023] In the remainder of the description, the casein and / or caseinate-based film is referred to as “casein film”.

[0024] Caseinate primarily refers to the sodium, potassium, calcium, or magnesium salts of casein and their mixtures. Unlike caseins, which are hydrophobic, caseinates are hydrophilic and therefore water-soluble.

[0025] Casein is a milk protein that is poorly soluble in water. It is advantageously obtained either by acidification (acid casein) or by enzymatic attack (rennet casein). In the context of the invention, caseins and caseinates are animal proteins derived from milk. Milk protein material therefore essentially means caseins, caseinates and their mixtures.

[0026] The Applicant had the idea of ​​applying the casein films conventionally used in the field of packaging to the field of lids used in capsules or stoppers in order to resolve the problems mentioned above.

[0027] More specifically, the Applicant found that the casein film presented at least three advantages: to be sealable on its own, which means that it can be sealed on the rim of a container at room temperature without requiring the addition of glue or the presence of a conductive material whose thickness is incompatible with an optimal recycling circuit, to be biodegradable.

[0028] More precisely, when the metal layer is present, it has a thickness such that it cannot fulfill a thermoinduction function. In practice, it has a thickness of less than 12 micrometers, preferably less than 10 micrometers, in practice only a few angstroms. Under these conditions, the metal layer only has a barrier function. It also has the advantage of maintaining a metallic appearance of the seal for the consumer.

[0029] In a particular embodiment, the cover is completely devoid of a metal layer.

[0030] As mentioned, the film may contain casein, caseinate, or a mixture of the two.

[0031] In practice, the film includes: at least one caseinate and / or at least one casein, the weight of which represents from 40 to 90% of the weight of the film, more advantageously from 50 to 85% and even more advantageously from 60 to 70% at least one plasticizing agent, the weight of which represents from 5 to 50% of the weight of the film, more advantageously from 10 to 40% and even more preferably from 15 to 25%.

[0032] Advantageously, the weight ratio between casein and caseinate is between 5 / 95 and 95 / 5, preferably between 20 / 80 and 80 / 20 and even more preferably, between 40 / 60 and 60 / 40.

[0033] In practice, the plasticizing agent may be chosen from the group comprising water, glycerol, sorbitol, mannitol, maltitol, ethylene glycol and mixtures thereof.

[0034] Preferably, the plasticizing agent is water and / or glycerol.

[0035] The sealability of the film is provided by the water-soluble nature of casein, which creates a sticky effect on the film. In other words, the film can be glued directly onto the rim by simply moistening the area to be glued with an aqueous solution.

[0036] In a particular embodiment, the cover is made solely of the casein and / or caseinate-based film.

[0037] To strengthen the mechanical characteristics of the film, the seal also includes a reinforcing film.

[0038] The reinforcing film is advantageously applied over the entire surface of the casein film, in order to compensate for any possible mechanical fragility of the latter. The reinforcing film can also serve as a support for printing. Logically, the reinforcing film is applied to the face of the casein film opposite that facing the rim. The reinforcing film is in practice made integral with the casein film either by moistening the reinforcing film or the casein film using an aqueous solution, or by means of a binder such as, for example, a two-component isocyanate-hydroxyl glue.

[0039] Preferably, the reinforcing film is made of a material advantageously chosen from the group comprising polyester (PET), biaxially oriented polypropylene, biaxially oriented polyamide and biaxially oriented PET, polyester, PE (polyethylene). Its thickness is advantageously between 5 and 100 µm, advantageously between 4 and 40 µm. In certain cases, the reinforcing film can be metallized without giving it thermoinduction characteristics. Only the barrier function is sought.

[0040] In practice, the operculum has a thickness of between 20 and 200 µm, preferably between 30 and 120 µm.

[0041] In an improved embodiment, the lid comprises a tab arranged in the extension of the reinforcing film and / or the casein film.

[0042] This is intended to make it easier to remove the seal.

[0043] Also disclosed is a two-piece seal comprising a support secured to a seal as described above by means of a temporary adhesive.

[0044] The support can be made of any type of compressible material with recovery memory, in particular expanded polyethylene or expanded polypropylene, possibly provided on at least one of its two sides with a polypropylene or polyethylene film to give it a certain rigidity. It can also be made of paper or cardboard. In practice, the supports envisaged have a thickness of between 0.5 and 4 mm, advantageously between 0.8 and 2 mm.

[0045] As regards the temporary bonding between the support and the seal, this can be obtained by means of a temporary adhesive applied in the form of a film, preferably extruded or co-extruded, each of the two faces of the layer having a different adhesive power, the most adhesive face being applied to the lower surface of the support, while the least adhesive face is applied to the upper face of the seal. In practice, such a film is based on a polymer, generally synthetic, and judiciously chosen by the person skilled in the art, so as to obtain the desired differential bonding properties. Such polymers are, for example, polymers or co-polymers based on acetate, acrylate, polyethylene, etc. The temporary adhesive can also be in the form of a layer of wax.

[0046] The lid and the double-piece seal are particularly suitable for sealing a container with a cap or capsule containing dry products. [ Fig. 1 ] there figure 1 is a schematic representation illustrating a container sealed with a lid according to the invention, where the lid comprises only the casein film. Fig. 2 ] there figure 2 is a schematic representation similar to that of the figure 1 , where the operculum comprises the casein film and a reinforcing film. Fig. 3 ] there figure 3 is a schematic representation similar to that of the figure 1 , except that the container is sealed with a double-piece seal according to the invention. Fig. 4 ] there figure 4 is a schematic representation similar to that of the figure 2 , where a seal is affixed to the lid.

[0047] A film is produced with the following composition in % by weight: casein: 50 caseinate: 5.5 glycerol: 20 water 24.5

[0048] The film is manufactured by extrusion, advantageously extrusion-inflation.

[0049] The lid of the invention is intended for closing containers such as bottles or jars with a stopper or capsule. In the following examples, the jar (1) is intended to be closed with a stopper (8).

[0050] In reference to the figure 1 , a pot (1) is shown sealed with a lid (2) according to the present invention. The lid (2) comprises, in this first variant, only a casein-based film (3) described above arranged opposite the rim of the pot.

[0051] The film is sealed by moistening the rim of the jar and then applying the casein-based film directly to the rim of the jar.

[0052] According to a second variant, illustrated by the figure 2 , the cover (2) comprises the casein-based film (3) and a reinforcing film (4).

[0053] The reinforcing film (4) is in this example made of bi-oriented PET. Its thickness is 35 µm.

[0054] The casein-based film (3) and the reinforcing film (4) overlap over their entire surface, the cover (2) being positioned on the rim of the pot (1) so that the casein-based film (3) is opposite the rim of the pot (1).

[0055] Still according to the figure 2 , the casein-based film (3) and the reinforcing film (4) are joined together by wetting the casein-based film.

[0056] In reference to the figures 3 et 4 , the cover (2) is secured to a seal (5), using a temporary adhesive.

[0057] The adhesive film (7) allowing temporary adhesion between the support layer (6) of the seal (5) and the cover (2) is chosen such that the assembly force between the support layer (6) and the cover (2) is lower than both the resistance force of the casein-based film (3) (also referred to as coherence force) and the bonding force of the casein-based film (3) on the rim of the container (1).

[0058] The adhesive film (7) is in the form of a coextruded film, each of the two faces of which has a different adhesive power, the most adhesive face being applied to the upper surface of the cover (2) while the least adhesive face is applied to the lower face of the support layer (6). In practice, this adhesive film (7) is a polymer based on acrylate and polyethylene.

[0059] The inner circumference of the stopper (8) further has a bead (not shown) for holding the support layer (6) at the bottom of the stopper (8) after opening. When the container (1) is first opened, removing the stopper (8) causes the support layer (6) (which then remains in the bottom of the stopper (8) thanks to the presence of the bead arranged on the inner circumference of said stopper (8)) to separate from the seal (2) which remains on the rim of the container (1). The stopper (8) is made of any suitable material, preferably polymer.

[0060] The support layer (6) can be made of any type of compressible material with recovery memory, in particular expanded polyethylene or expanded polypropylene, possibly provided on at least one of its two faces with a polypropylene or polyethylene film to give it a certain rigidity. In practice, the support layer (6) has a thickness of 2 mm.

[0061] There figure 3 represents the support layer (6) secured to the upper face of the casein-based film (3) which alone constitutes the cover (2), while the figure 4 represents the support layer (6) secured to the upper face of the reinforcing film (4); the cover (2) this time being composed of the reinforcing film (4) and the casein-based film (3).

[0062] In reference to the figures 1 à 4 , the casein-based film (3) has a thickness of 50 µm. The reinforcing film (4) has a thickness of 35 µm.

[0063] The invention and the advantages arising therefrom are readily apparent from the foregoing description.

[0064] In particular, we note the possibility of substituting the glue or the majority of the metal with casein, making it possible to anticipate possible regulatory problems linked to the use of glue and to recycle in the same circuit all the elements constituting the stopper or capsule, as well as the seal and the lid.

Claims

1. A lid for closing a container for closing with a stopper or a cap, comprising a casein- and / or caseinate-based film intended to be in contact with the rim of said container, characterised in that the film is extruded.

2. The lid (2) according to claim 1, characterised in that it further comprises a reinforcing film (4).

3. The lid (2) according to claim 2, characterised in that the reinforcing film is applied on the face of the casein film opposite that facing the rim.

4. The lid (2) according to any one of claims 2 to 3, characterised in that the reinforcing film is made of a material chosen from the group comprising polyester (PET), biaxially oriented polypropylene, biaxially oriented polyamide and biaxially oriented PET.

5. The lid according to any one of claims 2 to 4, characterised in that it comprises a strip arranged in the extension of the reinforcing film and / or of the casein- and / or caseinate-based film.

6. The lid according to claim 1, characterised in that the casein- and / or caseinate-based film comprises: - at least one caseinate and / or at least one casein, the weight of which represents 40 to 90% of the weight of the film, more advantageously 50 to 85%, and even more advantageously, 60 to 70%, - at least one plasticising agent, the weight of which represents 5 to 50% of the weight of the film, more advantageously, 10 to 40%, and even more preferably, 15 to 25%.

7. The lid according to claim 6, characterised in that the plasticising agent is chosen from the group comprising water, glycerol, sorbitol, mannitol, glycol ethylene and their mixtures.

8. A use of the lid according to any one of claims 1 to 7 for the sealing of the container containing dry products.