WO2010063894A1

WO2010063894A1 - Crowning method making it possible to achieve the tamper-resistant closing of a container

Info

Publication number: WO2010063894A1
Application number: PCT/FR2009/001325
Authority: WO
Inventors: Jacques Granger; André LUClANl; Johann Paintendre
Original assignee: Alcan Packaging Capsules
Priority date: 2008-12-01
Filing date: 2009-11-18
Publication date: 2010-06-10
Also published as: EP2352691A1; PL2352691T3; FR2939118A1; ES2446665T3; HRP20140325T1; EP2352691B1; PT2352691E

Abstract

The present invention relates to a method for crowning a container, wherein a container (10) having a neck (11) and a crown cap (30) with an apron is provided, the neck of said container with said crown cap is covered, said crown cap (30) is clamped onto said neck, and said container (10) having said crown cap is removed, characterized in that, in order to obtain a tamper-resistant closing of said container, a) said apron includes an area (31) covered with a plastic material layer that is heat-sealable at a sealing temperature greater than 45°C; b) after placing and clamping said apron onto said neck, said apron is compressed onto the neck by means of an external tool (100) that is radially engageable with said covered area (31); c) while maintaining said compression, said compressed covered area is heated such that said layer reaches said sealing temperature; and d) the heating is stopped, compression is stopped, and the neck (11) is freed from said external tool (100).

Description

CAPSULING PROCESS FOR REALIZING THE INVIOLABLE CLOSURE OF A CONTAINER

The invention relates to the field of overcap capsules of containers or bottles containing in particular wines, alcohols, aperitifs and, in general, all alcoholic beverages. It relates more particularly overcap caps with anti-fraud means.

Many caps are already known to cover the neck of a bottle already closed by a plug. Some caps, intended to top bottles of sparkling wines such as champagnes, are very thin caps obtained by rolling a metallic or metalloplastic skirt.

(Of thickness typically less than or equal to 50 microns) and then welding or heat sealing of a head on the skirt. These caps are placed on the neck of a bottle closed by a cap. Their skirt is then folded, typically in 4 folds, to be pressed against the neck. Patent FR 2,835,510 of the applicant describes an anti-fraud means particularly well suited to this type of overcap, resulting from the introduction of a "glue point" between the top of the cap and the head of the cap : even if the skirt can still be easily unfolded, the head - which usually includes a tax stamp and / or the logo of the drink contained - is systematically destroyed during the detachment of the capsule.

[0003] A very large number of other caps for overcapping certain bottles of wine, alcohols or liquors are thicker metal parts, typically greater than or equal to 60 μm in thickness. These capsules are parts which comprise a head and a slightly conical skirt and which are generally obtained by stamping-drawing a blank cut in a metal strip. During the so-called "capping" operation, they are placed on the neck of a bottle already closed by a stopper and are crimped, typically by crimping on a counter-glass ring present on the outer surface of the neck. from the bottle. European Patent EP 1 397 297, also belonging to the applicant, describes a closure system with anti-slip means. fraud particularly suitable for this type of overcap. In this patent, the neck of the bottle has on its outer surface not only a counter-crimping ring but also a groove. A portion of the skirt, that opposite the throat when the cap covers the neck, comprises, on all or part of its inner surface, a material

Adhesive to form an adhesive layer capable of adhering to all or part of said groove. After deformation during capping, the skirt comprises a ring-shaped portion narrowed in the groove and all or part of the necking ring adheres to the groove, thanks to the adhesive layer. In this way, any attempt at fraudulent separation of the capsule causes the rupture of the capsule and in particular of the ring narrowed in the throat, making

And thus visible said attempted fraud.

The Applicant however found that the at least partial bonding of the metal skirt on the glass neck during the capping operation was very difficult or impossible to achieve under satisfactory industrial conditions, namely in

/ 5 respecting the typical capping rates of the bottles, namely 10,000 to 20,000 bottles per hour. In particular, it is necessary to avoid any cold-curable adhesive such as a cyanoacrylate because it suffices for a poor spot dosage, simply due to a barely noticeable operating drift (gradual plugging of nozzles compensated by an increase in the injection pressure glue, etc.), so that "coulures"

20 appear suddenly on the outer wall of the capsulated bottle, appearance whose consequences can be catastrophic on the packaging line.

[0005] The Applicant has therefore set itself the objective of defining an industrial capping process incorporating the production of a tamper-proof closure system making it possible to obtain an adhesion of the overcap capsule to the neck of the bottle which is strong enough to make impossible any removal of the capsule that would not lead to the destruction thereof, and this without increasing the risk of damage to the packaging line or substantially reduce industrial production rates.

[0006] A first object according to the invention is a method of capping a container in which a container provided with a neck and an overcap capsule is supplied. comprising a skirt, the collar of said container is cap with said capsule and said capsule is placed on said neck, then said container with its capsule is removed, in which, to obtain a tamper-proof closure of said container, a) said skirt of such that it comprises, on at least a portion of its inner surface, a coated zone covered by an adhesive material; b) after setting up said skirt on said neck, said skirt is fixed on the neck by crimping or heat shrinking according to the nature of said capsule; characterized in that: c) said adhesive material is a heat-sealable plastic material; d) after having fixed said skirt on said neck, said skirt is locally plated on said neck, exerting a compression force on said skirt, at at least a part of said coated zone, called "compression zone", using an external tool, the active part of which normally moves on the surface of said neck, said compression force being applied so that an intimate contact of said skirt with said neck in said zone of contact is obtained; compression; e) while maintaining said compressive force, said compression zone is heated, so that said heat-sealable plastic material reaches said sealing temperature, typically greater than 45 ° C., preferably greater than 60 ^° C., of more preferably above 75 ⁰ C; d) then the heating is stopped, said compression force is canceled and the neck of said external tool is released.

In the context of this invention, it is provided with a capsule comprising at least one skirt which is substantially cylindrical, or rather slightly conical. This capsule does not necessarily include a head, that is to say a transverse wall. However, even if this is not compulsory, the invention is of interest when the capsule performs an overcap function: the container is already plugged by a permanent-use stopper, for example a cap, and is covered with an overcap, the transverse wall of which retains said stopper for permanent use. This capsule serves in particular as a first-opening indicator: to access said cap, it is necessary to first destroy said capsule. Are more particularly concerned in the Embodiments of the present invention include stamped metal caps, typically of tin or aluminum alloy, which cover most high-alcohol beverage bottles as well as plastic sleeves which preferably fill the overcap function - have a transverse wall at least partially covering said permanent-use stopper. Advantageously, the plastics material of these sleeves is heat-shrinkable. On the other hand, the present invention lends itself less well to overcap caps, usually used to cover bottles of sparkling wines, for example champagne bottles, in particular when their skirts are obtained by rolling-welding, because the conditions of the intimate contact between neck and skirt over the entire circumference, essential to avoid the risk of local melting of the skirt, are, because of conventional bending performed on this type of cap, more difficult to obtain.

According to the invention, said skirt comprises, on at least a portion of its inner surface, an area called "coated zone", covered with a heat sealable plastic material. By using such a material, it avoids the risks of strong adhesion after contact at room temperature, which can lead to a total and irreversible damage to the packaging line. The term "hot-sealable plastic material" is understood to mean a plastic material which, when it is brought into contact at ambient temperature, presents, with the material of the container, typically glass or a plastic material, and the materials of the packaging line, a zero or low adhesion and reversible with said materials but which, when brought to a certain temperature, called sealing temperature, generally slightly lower than the melting temperature or the glass transition temperature, present, after return to the ambient temperature, a strong and irreversible adhesion with the material of the container. This adhesion is strong and irreversible in that, at room temperature, to destroy the assembly thus produced, it is necessary to impose a force that causes a rupture within one of the materials but not their interface.

In the context of the invention, the sealing temperature of the material is greater than 45.degree. C., preferably greater than 60.degree. 75 ° C. Said material has a high viscosity at room temperature but, at said sealing temperature, its viscosity decreases and its surface tension becomes such that said material closely marries the relief of the surface in contact with which it is located. As the operation is reversible, this sealing temperature must be sufficiently

High for a take-off by heating at a relatively low temperature is difficult to achieve, that is to say, so that the takeoff can not be achieved with rudimentary means, typically a hair dryer or a heat gun, but only with a device containing powerful heating means for concentrating a high energy in a fraction of a second on localized area precisely, the

The development and development of such a device thus presents a technical and economic obstacle such that it should discourage most attempts at fraud.

The applicant had found, particularly when it came to making a tamper-proof closure on glass bottles, that the implementation of the tools used

/ 5 to deform the overcap caps, typically by knurling, or the sleeves, typically by heat shrink, were not sufficient to ensure an irreversible fixation on the neck that is reliable under the conditions imposed by the current industrial packaging rates, and this even if we used the most efficient hot sealable materials known. After many attempts, it 0 found that it was necessary to use a specific tool, which allows to externally apply a compressive force to press the coated area of the skirt on the neck, said compressive force being directed normally relative to the neck surface at the compression zone, and maintain said compressive force as said zone is heated to the sealing temperature, i.e., during the heat seal operation.

According to the invention, after setting up and fixed said skirt on said neck, typically by crimping or heat-shrinking, it is locally plated on said neck by exerting a compressive force with the aid of an external tool of which the active part normally moves on the surface of said neck, at the compression zone, so that an intimate contact of said skirt with said neck in said compression zone is obtained. Since, at the level of the compression zone, the skirt and the neck have cylindrical walls, the compression force is a radial force with respect to the axis of the neck.

[0012] By intimate contact is meant a contact in which the difference between the

The actual contact area and the apparent contact surface is essentially due to the respective roughness of the surfaces concerned. Intimate contact is also understood to mean a contact in which no "delamination" is observed between the skirt and the collar which would extend over a distance that would typically have the same order of magnitude as the thickness of the skirt. To obtain an intimate contact between the zone covered with the skirt and the collar, it is therefore

It is recommended to avoid the formation of interstices resulting from the formation of such detachments. Applicant has associated with these interstices the appearance of defects related to the local melting of the skirt, due to the lack of rapid cooling portions of skirt that are not in direct contact with the glass. Such interstices appear in particular when one forms, voluntarily or otherwise, folds on the skirt to press it

/ 5 on the collar.

By imposing on the active part of the external tool a normal displacement, that is to say perpendicular to the surface of the neck, it is made to ensure that it exerts a normal compression force on the contact surface. with a low risk of sliding in a plane tangential to said contact surface, that is to say, typically in the circumferential and / or axial direction, of the skirt with respect to the neck and thus avoiding the formation of folds. An external tool such as a wheel, such as the tool used in EP 1 397 297, which can be applied normally to the surface of the skirt but whose active part (the rotating part of the wheel) does not normally move to said surface of the skirt, is

25 likely to move the skirt relative to the neck and to form either folds or detachments. Such a tool is therefore not recommended in the context of the invention. Since the compression zone has a certain circumferential extent, it is advantageous to aim for a force which is distributed over the contact surface and which is at all points directed in a direction as close as possible to the normal direction. In the embodiments

Preferred embodiments of the invention, presented hereinafter, are chosen tools that exert a normal compression force (in this case radial since skirt and neck are cylindrical at the of the compression zone), distributed substantially uniformly over the entire circumference of the skirt, for example an inflatable toroidal pocket whose interior is pressurized with hydraulic or pneumatic pressure, or an elastomeric ring which is deformed in such a way that that its internal bore decreases in diameter.

As it is preferable to avoid the formation of folds, the present method applies essentially to the metal overcap caps that are rolled and crimped around the neck or to the heat-shrinkable plastic sleeves, whose diameter, under the effect of a short current of hot air can decrease substantially, until it reaches, if it was alone, a significantly smaller diameter, typically more than 40%, to the diameter of the neck. Some Champagne caps, quite thick and obtained by stamping, can also be well suited to the process according to the invention. On the other hand, most overcap caps for sparkling wines and champagnes, which are produced by rolling-welding planar blanks made of aluminum alloy or metalloplastic, are too fine to be crimped and need to be pressed to be plated on. the neck of the container so that, once plated on said neck, these caps have folds and small recesses that make their skirt not intimately in contact with the neck on its entire circumference. In addition, the longitudinal weld resulting from the rolling-welding has dielectric properties different from the rest of the skirt, which make this type of cap unsuitable for the implementation of the preferred heating method employed in step c) of the process according to the invention. invention, namely induction.

We have seen that the sealing temperature was preferably quite high. But, preferably, it should not be too high, because the higher it is, the more it requires powerful heating means and the greater the risk of degradation is great for the capsule, the container and the liquid it contains as well as for the compression device. In addition, the material used itself has a temperature limit of use, for example its flash point. That is why, advantageously, the heat-sealing material is chosen such that its sealing temperature is less than 130 ^° C., preferably less than ^{0 °} C., more preferably less than 85 ° C. Typically, the plastic material is a heat fusible adhesive which is deposited on the inner surface of the skirt of the capsule by application of a varnish, by projection of a liquid dispersion, or by depositing a molten thermoplastic layer. Preferably, said inner surface is covered over its entire circumference, so that an annular coated area covered with a layer of substantially constant thickness is obtained.

Preferably, in particular for the metal overcap capsules, a liquid dispersion is chosen comprising an olefinic copolymer comprising acid groups, for example an EAA (ethylene-acrylic acid) copolymer. In order to be able to seal at a temperature of about 80 ° C, it is recommended to choose an EAA copolymer with a flash point above 90 ° C.

Advantageously, in the context of the example described below, a dispersion of EAA marketed under the reference MICHEM (registered trademark) PRIME 4983R-

HSA.

Advantageously, said heat-sealable material is used in the form of a varnish or a liquid dispersion and is deposited on the inner surface of said skirt with a spray gun, a brush or an ink-jet type technique. The thickness of the deposited layer is typically of the order of 10-20 μm. Preferably, the coated zone has a shape delimited by a contour having angles, so that, by edge effect, break primers appear at the least stress on the skirt. The angles are for example made by projection through a mask.

For heat-shrinkable plastic sleeves, it is possible to use a sleeve prepared according to the process described by the applicant in its patent EP 1 682 331 and deposit on the inner surface of said sleeve a heat-sealing varnish or a coating of hot-melt adhesive resin (hot melt). ), for example based on SIS rubber (poly (styrene / isoprene / styrene)) or acrylic materials. But it is also possible to make the sleeve itself by coextrusion of an outer layer of a material thermoplastic suitable for a method of manufacturing shrink skirt such as that described in EP 1 682 331 and an inner layer, typically thinner, a hot melt adhesive resin.

. The quality of the glass of the bottle is also to be taken into account to determine the best hot sealing conditions. So, it is well known that the

The bottling process, whatever it may be (blown-blown or pressed-blown), ends with a finishing phase where the blank is blown internally so that it comes to be pressed. towards the inner wall of the finishing mold. After this blowing phase, the bottles are extracted from the finishing mold, and transferred to a conveyor belt which leads them to a surface treatment tunnel and an annealing arch.

At the outlet, the temperature of the glass is still high: the outer walls of the bottle cool suddenly and contract, while the interior reacts more slowly due to the poor thermal conductivity of the material. This results in the establishment of tensile stresses at the periphery of the bottle which weaken and may cause a subsequent breakage. In order to release and equalize these stresses, the glass is heat-treated by passing through an annealing arch. In addition, in order to limit the consequences of the microdefects existing on the surface of the bottle, surface treatments are performed hot and on the cooled bottle. The hot surface treatment takes place between the exit of the finishing mold and the annealing arch. Its purpose is to prevent not only the propagation of created microcracks

During the forming but also the appearance of new cracks during the hot contact between the bottles and the guide members. It consists in projecting onto the bottle metal halide vapors (typically tin or titanium chloride) which react with the surface of the glass to form an invisible layer of metal oxide a few nanometers thick. In addition to this heat treatment, a

Surface treatment on the cooled bottle in order to increase the sliding coefficient of the glass, which makes it possible to transport the bottles at a high rate over the bottling lines, avoiding the creation of scratches or abrasion marks. This treatment takes place at the exit of the annealing arch and consists of depositing on the surface of the bottles a protective and lubricating film, polyethylene wax type or polyoxyethylene monostearate.

If the method is advantageously applied to the irreversible sealing of all glass bottles usually intended to package alcoholic beverages, the Applicant has found that the method according to the invention gave particularly good results when the bottle was prepared. so that the neck remains raw heat treatment, that is to say, coated with the only nanometric layer of metal oxide.

According to the invention, said skirt is compressed on the neck and, while maintaining said compression, heating at least a portion of said compression zone, so that said heat-sealable plastic material reaches said temperature of sealing. Because of the particularly high conditioning rates, it is preferable to perform this heating for as short a time as possible. Advantageously, the induction heating is carried out, using frequencies typically between 10 and 400 kHz, preferably between 100 and 200 kHz, and inductor powers of between 1 and 10 kW, preferably around 3 kW, which are functions of many parameters such as the distance of the inductor with respect to the zone to be heated, the geometry of the zone to be heated, the nature of the heat-sealable material, the radial compression force, etc. .

Of course, when the capsule to be heated is a heat-shrinkable plastic sleeve, it is recommended to use a plastic material filled with metal particles or iron oxide, comprising for example at least 10% by weight of such particles. On the other hand, to perform a more efficient and more accurate heating of the target area, while disturbing as little as possible the vicinity of this area, focus the field lines with ferrite blocks judiciously placed and limit in the space the electric field created by the inductor using for example a copper ring placed so that it protects the bottom of said skirt against edge effects.

In the preferred embodiments of the invention, induction heating is carried out on the entire circumference of the capsule, targeting the part of the capsule which carries the coated zone. This is done using a solenoid comprising one or more turns completely surrounding said neck. Preferably, in the case of metal overcap caps, a copper tube approximately 4 mm in diameter, in the form of a loop, is used as the inductor, typically a solenoid having one to five turns, preferably two / 0 or three, surrounding completely the collar. Thus, to reach the targeted sealing temperature (typically 80 ° C) at the level of the EAA copolymer layer, 10-20 μm thick and about 20 mm wide, which covers an annular zone of the inner surface of the inner skirt. a tin-alloy pressed capsule, said skirt having a thickness of 100 μm and a diameter of about 30 mm, using a 100-200 kHz generator associated with a solenoid-shaped inductor with three turns forming 80 diameter of approximately, connected to a generator capable of delivering a heating power of about 3.7 kW. By using the generator at 70% of its heating power, the desired sealing temperature in the area of the capsule-neck interface is reached in a time which is of the order of one second.

According to the invention, a compressive force is exerted to press said skirt on the neck, with the aid of an external tool whose active part normally moves on the surface of the neck, at the level of said zone. compression. Several features are possible to fulfill the role of this external tool:

a device comprising jaws with substantially radial displacement surrounding the neck as completely as possible;

an inflatable toroidal pocket whose interior is pressurized hydraulically or pneumatically;

or an elastomeric ring that is deformed so that its internal bore decreases in diameter, for example a ring having a transverse wall

End and its outer side wall confined within an outer jacket, and subjected to the effect of axial compression exerted on the other end transverse wall, typically using a piston, the bore of the outer sleeve acting as a stop opposing the centrifugal radial displacement of the side wall of said elastomeric ring.

Whatever tool is used, it is positioned closer to the neck, between it and the induction loop. As it must be in contact with the skirt of the capsule and it necessarily occupies a certain volume, the inductor must be far enough away from said neck. For example, for a 30 mm capsule, it is in the form of one or more 80 mm diameter loops.

The radial compression of the skirt on the collar must be effective over the entire circumference of the skirt, during the heating period and preferably a little after, during cooling. It is not easy to estimate the value of the radial compression to be applied. It is easier to define the macroscopic force imposed by the tool, which is transmitted in the form of a circumferentially distributed radial compressive stress. Thus, for the sealing of a capsule 30 mm in diameter on the neck of a glass bottle, by making an irreversible adhesion on an annular zone high of nearly 20 mm:

- In the case of a device comprising three jaws with substantially radial displacement, is applied to each of these jaws a typical effort of the order of 2000-2500 N; the clamping jaws are covered by an elastomer to distribute the pressure; the choice of elastomer is important on the rendering after sealing;

- In the case of an inflatable torch bag, an internal pressure of between 2 and 6 bar is typically applied, depending on the shape of the force application surface and the material of the force application means used. . in the case of an elastomeric ring 52 mm in outside diameter and 32 mm in internal diameter, the elastomeric material having a hardness of the order of 40 Shore A, an axial force of the order of 1000 newtons is typically applied.

According to the invention, after having pressurized the annular zone coated and brought to the sealing temperature, the heating is stopped, the compression is canceled and the neck of said external tool is released. When the layer of plastic material heat-sealable returns to room temperature, irreversible adhesion is obtained, at room temperature, between the skirt of said capsule and the wall of the container: any action intended to remove the capsule to access the permanent-use stopper results in a rupture of said capsule leaving on the neck traces very difficult or impossible to erase.

In the industrial conditions of a packaging line, the use of an inductor is, as we have seen, highly recommended so as to minimize heating time. Under such conditions, the cooling of the layer is actually very fast because the glass, which has a large mass relative to the capsule, has not had time to heat, so that the capsule, because of its low thermal inertia, found by conduction through its entire contact surface on the neck, the ambient temperature in fractions of a second. In order for the cooling to be effective, it is important to have good contact between the collar and the skirt of the capsule in all places. Preferably, the compression is maintained for a fraction of a second after stopping the heating.

The heating energy transmitted by the inductor is so strong, it is important to ensure that the contact between the neck and the annular zone of the skirt of the capsule subjected to heating is as intimate as possible: by avoiding the presence of any gap between the skirt and the collar, as small as it is, it avoids a local fusion of the capsule that would make the container thus capsulated unsuitable for sale.

FIG. 1 represents, in front view and in diametral section, a heat-sealing device under compression enabling the method according to the invention to be implemented inside a packaging line for bottles of spirits clogged with using a cap with a cap covered with an overcap 30 mm in diameter. The overcap 30 has been obtained by stamping a tin blank and has a slightly conical head and skirt. The neck 11 of the bottle, here in glass, is capped with said overcap, which is placed on said neck and crimped using conventional means such as knobs, the skirt of the wedding capsule. after crimping the external relief of the neck of the container, typically comprising a glass ring and a crimping groove.

To obtain a tamper-proof closure of said capsule, it is prepared, before its introduction on the neck, the capsule so that its skirt 33 comprises, on at least a portion of its inner surface, a coated zone 31 , covered with a layer of a

A hot-meltable plastic material, a copolymer of ethylene and acrylic acid (EAA) marketed in the form of an aqueous dispersion under the reference MICHEM (registered trademark) PRIME 4983R-HSA. This material has an optimum sealing temperature in the vicinity of 75 ° C - 85 ⁰ C: below the adhesion is insufficient, above the temperature is too close to its flash point (93 ⁰ C). The aqueous solution has been deposited

/ 5 by projecting through the nozzle of a pistol inserted inside the capsule. The coated zone 31 is a thick ring of about 10-20 μm, having a height of about 20 mm, and whose lower edge is about 3 mm from the open end 32 of the skirt. After setting up, plated and crimped the skirt on the neck, the skirt is compressed on the neck, with the aid of an external tool acting radially with respect to the axis of said neck, at the level of the annular zone coated and heated at least the annular zone under compression. This tool, which also comprises the heating means, is illustrated in FIG. 1: it is a heat-sealing device under compression 100 placed around the neck 11

25 of the bottle 10 filled and plugged with a cap 20 and capsulated cap, the overcap 30 being crimped on said neck. This compression heat-sealing device comprises a compression assembly 110, comprising a liner 111 surrounding and bearing on the neck, a piston 112 and an elastomeric ring 113, an inductor represented here by a solenoid 120 comprising three induction loops, a

Ferrite ring 140 and a copper ring 130. The lower transverse wall 1131 and the side wall 1132 of the elastomeric ring 113 are confined inside the bore of the liner 111. When actuating the piston 112, the latter exerts an axial force on the upper transverse wall 1133 of the elastomeric ring by means of the ferrite ring 140. The liner 111 has a bottom 1112 pierced with a central hole whose edge matches the shape of the neck 11 at the level where it bears on this one. The bore 1111 of the liner 111 serves as a stop against the centrifugal radial displacement of the side wall 1132 of the elastomeric ring 113. The elastomeric ring has an internal diameter of 32 mm and an outside diameter of 52 mm. mm. When free of stress, the elastomeric ring has a height of 30 mm. Its lower end, the lower transverse wall 1131, is placed so that, when the compression assembly 110 is mounted on the neck of the bottle, it arrives approximately at the lower end 32 of the capsule 30. L The elastomer of the ring 113 has a Shore A hardness of 40. The bore 1134 of the elastomeric ring 113 is cylindrical. Under the effect of an axial force imposed by the piston 112, the elastomeric ring 113, initially 30 mm high, decreases its height to about 26 mm while the wall of its bore 1134 comes gradually into contact with the capsule crimped on the neck under the effect of the centripetal radial displacement imposed by the axial force of the piston 112. In this way, the coated zone, about 20 mm high, is approximately in the middle of the high compression zone of 26 mm approx.

The liner Ul has an inner diameter of about 52 mm and an outer diameter of 76 mm. It is made of a plastic material, a polyamide of the ertalon (registered trademark) type, used particularly for its anti-friction properties. The piston 112, with an outside diameter of about 52 mm, is also of a polyamide of the ertalon type.

The heating device comprises a power supply, a generator, a control box and a solenoid 120 with three loops constituted by a copper tube of diameter 4 mm, covered with an insulator and inside which flows from the outside. 'cooling water. It is connected to a 3.7 kW generator that is operated for heating at 70% of its nominal power, the frequency emitted being between 100 and 200 kHz. Solenoid 120 has an outer diameter of about 80 mm. The ferrite ring 140 makes it possible to concentrate the field lines and to increase the intensity of the induced currents. The copper ring 130 spatially confines the heating zone, protecting in particular the bottom of the skirt against edge effects.

The heating typically lasts between 1 and 2 seconds, the time to be sufficiently large so that one reaches at the level of the EAA layer a sealing temperature, typically between 75 ° C and 85 ⁰ C. We stop heating as soon as this maximum temperature is reached, to avoid degrading the sealing material and the capsule, the bottle and its contents. The compression is maintained for a fraction of a second after the heating has been stopped.

The device 100 for heat sealing under compression allows sealing on the entire circumference of the capsule and a height of at least 20 mm.

The optimal induction time and the delivered power are defined according to the results obtained, the adhesion being evaluated by a test for measuring a peel force.

In this test, a 12 mm strip is cut around the glued area around the circumference of the capsule and the force required to take off this tab is measured with a movement speed of 100 mm / min and a peel angle of 90 °. . The measured force, divided by the width of the band, is expressed in N / cm. A 90 ° peel test is described in ISO 8510-1.

When a peel force of around 15 N / cm is reached, it is found that the adhesion is sufficiently strong to be considered as an irreversible seal because the rupture at ambient temperature takes place in the adhesive material, a part of the adhesive remaining anchored to the glass of the bottle.

Claims

1. A method of capping a container in which a container (10) provided with a neck (11) and an overcap (30) comprising a skirt is provided, the neck of said container is capped with said capsule and plate said capsule on said neck, then

Removing said container having its capsule, wherein, to obtain a tamper-proof closure of said container, a) said skirt is selected such that it comprises, on at least a part of its inner surface, a coated zone (31) covered by an adhesive material; b) after setting up said skirt on said neck, said skirt is fixed on the neck by crimping or heat-shrinking according to the nature of said capsule; characterized in that: c) said adhesive material is a heat-sealable plastic material; d) after having fixed said skirt on said neck, said skirt is locally plated on said neck, exerting a compressive force on said skirt, at at least a portion of

Said coated zone, referred to as a "compression zone", with the aid of an external tool, the active part of which normally moves on the surface of said neck, said compressive force being applied so as to obtain an intimate contact of said skirt with said neck in said compression zone; e) while maintaining said compressive force, said compression zone 0 is heated so that said heat-sealable plastic material reaches said sealing temperature, typically greater than 45 ° C, preferably greater than 60 ^° C .; more preferably above 75 ° C; f) then the heating is stopped, said compression force is canceled and the neck of said external tool is released. 5

2. A method of capping a container according to claim 1 characterized in that it exerts with said external tool a normal compressive force, distributed substantially homogeneously over the entire circumference of said skirt.

3. A method of capping a container according to claim 1 or 2, characterized in that said hot sealable material is deposited on the entire circumference of the inner surface of the skirt so as to obtain an annular coated area.

4. A method of capping a container according to any one of claims 1 to 3, characterized in that said heat sealable plastic material is selected such that its sealing temperature is below 130 ° C, preferably less than 110 ° C., more preferably less than 85 ^° C.

5. A method of capping a container according to any one of claims 1 to 4 wherein depositing said heat sealable plastic material on the inner surface of the skirt of said capsule by applying a varnish, by projection of a liquid dispersion, or by depositing a thermoplastic layer.

6. A method of capping a container according to any one of claims 1 to 5 wherein, for the tamperproof closure of a metal overcap, is used an olefinic copolymer comprising acidic groups, for example a copolymer EAA (ethylene-acrylic acid), preferably having a flashpoint greater than 90 ^° C.

7. A method of capping a container according to any one of claims 1 to 6 wherein said hot sealable material in the form of varnish or liquid dispersion and is deposited on the inner surface of said skirt with the gun, by brushing or by an ink jet printing type technique, the thickness of the deposited layer being typically of the order of 10-20 μm.

8. A method of capping a container according to claim 7 wherein a mask is used during the projection of said hot sealable material whose shape is chosen to obtain a coated zone delimited by a contour having angles,

So that, after heat-sealing, by edge effect, break primers occur at the least stress on the skirt of said capsule.

9. A method of capping a container according to any one of claims 1 to 5 wherein, for the tamper-proof closure of a heat-shrinkable plastic sleeve, is deposited on the inner surface of the sleeve a heat-sealing varnish or a coating of resin hot melt adhesive.

10. A method of capping a container according to any one of claims 1 to 5 wherein, for the tamper-proof closure of a heat-shrinkable plastic sleeve, using a sleeve comprising a co-extruded skirt, comprising at least one

Outer layer of a thermoplastic material and an inner layer of a hot melt adhesive resin.

11. A method of capping a container according to any one of claims 1 to 10 wherein said container is a glass bottle prepared so that the neck

/ 5 remains gross heat treatment.

12. A method of capping a container according to any one of claims 1 to 11 wherein said heating is carried out in step c) by induction, using frequencies between 10 and 400 kHz, preferably between 100 and 200 kHz, and 0 powers to the inductor of between 1 and 10 kW, preferably around 3 kW.

13. A method of capping a container according to claim 12, wherein for making the tamper-proof closure of heat-shrinkable plastic sleeves, sleeves containing at least 10% by weight of metal particles or iron oxide are used.

14. A method of capping a container according to any one of claims 2 to 13, wherein said external tool by means of which one exerts said substantially homogeneous compression over the entire circumference of the skirt is an inflatable torch bag of which 0 the inside is put under a hydraulic or pneumatic pressure.

15. A method of capping a container according to any one of claims 2 to 13, wherein said external tool by means of which one exerts said substantially homogeneous radial compression over the entire circumference of the skirt is an elastomeric ring (113). ) that is deformed so that its bore (1134) decreases in diameter, by

For example, a ring having its bottom transverse wall (1131 and its side wall (1132) confined within an outer jacket (111), and subjected to the effect of axial compression exerted on the upper transverse wall ( 1133), typically using a piston (112), the bore (1111) of the outer jacket acting as a stop opposing the centrifugal radial displacement of the side wall (1132) of said elastomeric ring .

/ 0

16. A method of capping a container according to claim 15, wherein, for the tamper-proof closure of a metal cap for overcoupling a glass bottle containing an alcoholic beverage, a compression heat-sealing device comprising

A) a compression assembly (110) comprising a jacket (111) having a bottom

(1112) pierced with a central hole whose edge conforms to the shape of said neck (11) at the point where it bears on it, a piston (112) and said elastomeric ring (113); b) an inductor comprising a solenoid (120) surrounding said jacket, and optionally for each of them: 0 cl) a ferrite ring (140) located between said elastomeric ring (113) and said piston

(112), c2) a copper ring (130) located at the open end of said overcap.