EP2352691B1 - Crowning method making it possible to achieve the tamper-resistant closing of a container - Google Patents

Description

The invention relates to the field of capsules for overcoupling 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 for overcaping bottles of sparkling wines such as champagnes are very thin caps obtained by rolling a metal or metalloplastic skirt (typically less than or equal to 50 μm in thickness) and then welding or heat sealing. 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. The 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.

A 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 microns thick. 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. The European patent EP 1 397 297 , also belonging to the applicant, describes a closure system with anti-fraud means more particularly adapted to 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, the one facing the groove when the cap covers the neck, comprises, on all or part of its inner surface, an adhesive material 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, thus making 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 by respecting the typical rates. bottle capping, ie 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" suddenly appear on the outer wall of the bottle capsulated appearance whose consequences can be catastrophic on the packaging line.

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

An object according to the invention is a method of capping a container according to claim 1.

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 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 process is less suitable for 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, has, after returning to the room temperature, strong and irreversible adhesion with the container material. 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. Since the operation is reversible, this sealing temperature must be sufficiently high that a take-off by heating at a relatively low temperature is difficult to achieve, that is to say, so that 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 realization and development of a such a device thus presenting a technical and economic obstacle such that it should discourage most attempts at fraud.

The Applicant has found, particularly when it comes to making a tamper-proof closure on glass bottles, that the use of the tools used to deform the caps, typically by knurling, or the sleeves, typically by heat-shrinking , were not sufficient to ensure an irreversible fixation on the neck that is reliable under the conditions imposed by the current industrial rates of packaging, and this even if one used the best performing hot sealable materials known. After many attempts, she 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 normally directed by relative to the neck surface at the compression zone, and maintain said compressive force while said zone is heated to the sealing temperature, i.e., during the heat sealing operation.

According to the invention, after setting up and fastening 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 whose 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.

By intimate contact is meant a contact in which the difference between the actual contact surface 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 skirted area and the collar, it is therefore 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 on the neck.

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 that it exerts a normal compression force on the contact surface with a weak 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 relative to the neck and thus avoids the formation of folds. An external tool such as a wheel, like 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 likely to move the skirt relative to the neck and form either folds or detachments. Such a tool is therefore not used 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 preferred embodiments of the invention, presented below, tools are chosen which 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 necessary 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, the diameter of which, under the effect of a short stream of hot air can decrease substantially, reaching, if it were alone, a substantially 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 folded 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 is 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 so that its sealing temperature is less than 130 ° C., preferably less than 110 ° C., more preferably less than 85 ° C.

Typically, the plastic material is a hot melt adhesive which is deposited on the inner surface of the skirt of the capsule by applying a varnish, by spraying 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 metal overcap capsules, a liquid dispersion comprising an olefinic copolymer comprising acidic groups, for example an EAA (ethylene-acrylic acid) copolymer, is chosen. 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 was used.

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 by means of a spray gun, a brush or by an ink jet printing 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 the heat-shrinkable plastic sleeves, it is possible to use a sleeve prepared according to the process described by the applicant in his patent EP 1 682 331 and depositing 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 which is suitable for a heat-shrink skirt manufacturing process such as that described in EP 1 682 331 and an inner layer, typically thinner, of a hot melt adhesive resin.

The quality of the glass of the bottle is also to be taken into account to determine the best conditions of heat sealing. Thus, it is well known that the shaping process of the bottle, whatever it is (blown-blown or pressed-blown), ends with a finishing phase where the blank is blown internally so that that it comes to press against 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 subjected to heat treatment by passing through a 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 microcracks created during 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 is carried out on the cooled bottle in order to increase the coefficient of sliding 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.

While the process is advantageously applied to the irreversible sealing of all the glass bottles usually intended for packaging alcoholic beverages, the Applicant has found that the process according to the invention gives particularly good results when the bottle has been prepared in such a way that 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, at least a portion of said compression zone is heated, so that said heat-sealable plastic material reaches said sealing temperature. 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 plastics 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, inductive heating is performed throughout the circumference of the capsule, targeting the portion of the capsule that carries the coated area. 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 or three, completely surrounding 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 pressed tin alloy capsule, said skirt having a thickness of 100 microns and a diameter of about 30 mm, using a generator of 100-200 kHz associated with a solenoid-shaped inductor with three turns making 80 mm of about diameter, 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.

• un dispositif comprenant des mors à déplacement sensiblement radial entourant aussi complètement que possible le col;
• une poche torique gonflable dont l'intérieur est mis sous pression hydraulique ou pneumatique;
• ou encore un anneau élastomérique que l'on déforme de telle sorte que son alésage interne diminue de diamètre, par exemple un anneau ayant une paroi transversale d'extrémité et sa paroi latérale extérieure confinées à l'intérieur d'une chemise extérieure, et soumis à l'effet d'une compression axiale exercée sur l'autre paroi transversale d'extrémité, typiquement à l'aide d'un piston, l'alésage de la chemise extérieure jouant le rôle d'une butée s'opposant au déplacement radial centrifuge de la paroi latérale dudit anneau élastomérique.

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 compression zone. 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 torus pocket whose interior is pressurized hydraulically or pneumatically;
• or an elastomeric ring which is deformed so that its internal bore decreases in diameter, for example a ring having a transverse end wall and its outer side wall confined within an outer jacket, and subjected to the effect of an 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 the tool 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.

• dans le cas d'un dispositif comprenant trois mors à déplacement sensiblement radial, on applique sur chacun de ces mors un effort typique de l'ordre de 2000-2500 N; les mors de serrage sont recouverts par un élastomère pour répartir la pression; le choix de l'élastomère est important sur le rendu après le scellage;
• dans le cas d'une poche torique gonflable, on applique typiquement une pression interne comprise entre 2 et 6 bars, selon la forme de la surface d'application de l'effort et le matériau du moyen d'application de l'effort utilisé.
• dans le cas d'un anneau élastomérique de diamètre extérieur 52 mm et de diamètre intérieur 32 mm, le matériau élastomérique ayant une dureté de l'ordre de 40 Shore A, on applique typiquement un effort axial de l'ordre de 1000 newtons.

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 with an external diameter of 52 mm and an internal diameter of 32 mm, 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, strongly recommended in order to minimize heating times. 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 that 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: avoiding the presence of any gap between the skirt and the neck, 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 compression heat-sealing device for carrying out the process according to the invention inside a packaging line for bottles of spirits clogged with the aid of a cap with a cap covered with an overcap of 30 mm 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 plate is placed on said neck and is crimped using conventional means such as knurls, the skirt of the capsule being crimped after crimping. 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, the capsule is prepared, before being placed on the neck, 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 heat-sealable 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 ° C: below the adhesion is insufficient, above the temperature is too close to its flash point (93 ° C). The aqueous solution was deposited by spraying through the nozzle of a gun introduced 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, using an external tool acting radially relative to the axis of said neck, at the level of the annular zone coated and heating 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 of the bottle 10 filled and plugged with a stopper 20. head 21 and capsulated, 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 within the bore of the liner 111 . When the piston 112 is actuated, the latter exerts an axial force on the upper transverse wall 1133 of the elastomeric ring via 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 it. The bore 1111 of the liner 111 acts 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. 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 about 26 mm.

The liner 111 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 circulates water of cooling. 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 duration must be large enough that one reaches at the level of the EAA layer a sealing temperature, typically between 75 ° C and 85 ° C. The heating is stopped 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 (16)

1. Method for capping a receptacle, in which a receptacle (10) is provided, fitted with a neck (11) and a closure capsule (30) comprising a skirt made from pressed metal or a plastics material, the neck of said receptacle is covered with said capsule and said capsule is pressed on said neck, and then said receptacle provided with its capsule is removed, wherein, in order to obtain a tamper-evident closure of said receptacle,

   a) said skirt is chosen so that it comprises, on at least part of its internal surface, a clad area (31), covered with an adhesive material;

   b) after having fitted said skirt on said neck, said skirt is fixed on the neck by crimping or heat shrinking depending on the nature of said capsule;

   c) said adhesive material is a hot-sealable plastics material;

   d) after having fixed said skirt on said neck, said skirt is pressed locally on said neck, exerting a compression force on said skirt, at at least part of said clad area, referred to as the "compression area", using an external tool, the active part of which moves, in relative movement, normal to the surface of said neck at said compression area, said compression force being applied so that a close contact, without the formation of folds, of said skirt with said neck in said compression area is obtained with a low risk of sliding in a plane tangential to said contact surface;

   e) while maintaining said compression force, said compression area is heated, so that said hot-sealable plastics material reaches the sealing temperature, above 45°C, preferably above 60°C, preferably again above 75°C;

   f) and then the heating is stopped, said compression force is withdrawn and said external tool is released from the neck.
2. Method for capping a receptacle according to claim 1, characterised in that, with said external tool, a normal compression force is exerted, distributed substantially evenly over the entire circumference of said skirt.
3. Method for capping a receptacle according to claim 1 or 2, characterised in that said hot-sealable material is deposited over the entire circumference of the internal surface of the skirt so as to obtain an annular clad area.
4. Method for capping a receptacle according to any one of claims 1 to 3, characterised in that said hot-sealable plastics material is chosen so that the sealing temperature thereof is below 130°C, preferably below 110°C, preferably again below 85°C.
5. Method for capping a receptacle according to any one of claims 1 to 4, wherein said hot-sealable plastics material is deposited on the internal surface of the skirt of said cap by applying a varnish, by spraying a liquid dispersion, or by depositing a thermoplastic layer.
6. Method for capping a receptacle according to any one of claims 1 to 5, wherein, for the tamper-evident closure of a metal closure capsule, an olefinic copolymer is used comprising acid groups, for example an EAA (ethylene-acrylic acid) copolymer, preferably having an ignition point above 90°C.
7. Method for capping a receptacle according to any one of claims 1 to 6, wherein said hot-sealable material is used in the form of a varnish or liquid dispersion and is deposited on the internal surface of said skirt by gun, brush or a technique of the ink-jet printing type, the thickness of the deposited layer being typically around 10-20 µm.
8. Method for capping a receptacle according to claim 7, wherein a mask is used during the spraying of said hot-sealable material, the form of which is chosen so as to obtain a clad area delimited by a contour having angles so that, after heat sealing, by edge effect, rupture initiations appear at the slightest stressing on the skirt of said cap.
9. Method for capping a receptacle according to any one of claims 1 to 5, wherein, for the tamper-evident closure of a heat-shrinkable plastic sleeve, a heat-sealing varnish or a coating of hot-melt adhesive resin is deposited on the internal surface of the sleeve.
10. Method for capping a receptacle according to any one of claims 1 to 5, wherein, for the tamper-evident closure of a heat-shrinkable plastic sleeve, a sleeve comprising a co-extruded skirt is used, comprising at least one external layer made from thermoplastic material and an internal layer made from a hot-melt adhesive resin.
11. Method for capping a receptacle according to any one of claims 1 to 10, wherein said receptacle is a glass bottle prepared so that the neck remains undressed after its hot processing.
12. Method for capping a receptacle according to any one of claims 1 to 11, wherein said heating at step c) is carried out by induction, using frequencies lying between 10 and 400 kHz, preferably between 100 and 200 kHz, and powers of the inductor lying between 1 and 10 kW, preferably around 3 kW.
13. Method for capping a receptacle according to claim 12, wherein, in order to effect the tamper-evident closure of heat-shrinkable plastic sleeves, sleeves are used containing at least 10% by weight of metal or iron oxide particles.
14. Method for capping a receptacle according to any one of claims 2 to 13, wherein said external tool by means of which said substantially even compression is exerted over the entire circumference of the skirt is an inflatable toric pouch the interior of which is put under hydraulic or pneumatic pressure.
15. Method for capping a receptacle according to any one of claims 2 to 13, wherein said external tool by means of which said substantially even radial compression is exerted over the entire circumference of the skirt is an elastomeric ring (113) that is deformed so that the bore (1134) thereof decreases in diameter, for example a ring having its bottom transverse wall (1131) and its lateral wall (1132) confined inside an external jacket (111), and subjected to the effect of an axial compression exerted on the top transverse wall (1133), typically by means of a piston (112), the bore (1111) of the external jacket fulfilling the role of a stop opposing the centrifugal radial movement of the lateral wall (1132) of said elastomeric ring.
16. Method for capping a receptacle according to claim 15, wherein, for the tamper-evident closure of a metal closure capsule of a glass bottle containing an alcoholic drink, a heat-sealing device under compression is used, comprising

    a) a compression assembly (110), comprising a jacket (111) having a bottom (1112) pierced with a central hole, the edge of which matches the shape of said neck (11) at the level where it comes into abutment thereon, a piston (112) and said elastomeric ring (113);

    b) an inductor comprising a solenoid (120) surrounding said jacket, and, optionally for each of them:

    c1) a ferrite ring (140) situated between said elastomeric ring (113) and said piston (112),

    c2) a copper ring (130) situated at the open end of said closure cap.

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