EP2533957A2

EP2533957A2 - Treatment of natural cork stoppers and stoppers obtained by said treatment

Info

Publication number: EP2533957A2
Application number: EP11708530A
Authority: EP
Inventors: Jacques Granger
Original assignee: Individual
Current assignee: Individual
Priority date: 2010-02-08
Filing date: 2011-02-07
Publication date: 2012-12-19
Anticipated expiration: 2031-02-07
Also published as: FR2956058B1; FR2956058A1; WO2011095713A3; WO2011095713A2; ES2421614T3; EP2533957B1; PT2533957E

Abstract

The treatment comprises the following steps a) to d): a) a batch of a plurality of so-called natural stoppers (900a) is provided and submerged in a liquid composition (903) comprising a polymer material (P), under a pressure P₁ higher than the atmospheric pressure P_A, b) then, optionally, the batch is treated in a vacuum, c) said batch is wrung out, and d) the batch is subjected to a heat treatment. Stoppers having a composite cork skin L impregnated with the polymer material P, symbolically represented by "L+P", are obtained.

Description

TREATMENT OF NATURAL CORK STOP PLUGS AND CAPS OBTAINED

BY THIS TREATMENT

FIELD OF THE INVENTION

The invention relates to the field of corking bottles of alcoholic and spirits wines using natural or technical cork stoppers, more specifically a treatment of natural cork stoppers in order to eliminate their disadvantages.

STATE OF THE ART

The nature of cork, natural product perfectly suited to the field of corking, can cause disadvantages, particularly because of its heterogeneity and the presence of harmful molecules - typically haloanisoles and halophenols - that can alter the taste of bottled products. As a result, there are no two identical plugs.

We know natural cork and the different treatments to obtain corks. First of all, in order to obtain so-called natural plugs, the plugs are subjected to washing with very hot water to remove small waste and particles of cork or dust, insects, etc. In order to obtain so-called treated plugs, a second superheated steam treatment is generally applied to natural plugs to reduce the content of harmful molecules and reduce the risk of having bottles that are unfit for consumption because they have a "corky taste", expression generally used to designate an unacceptable organoleptic alteration of the bottled liquid due to contamination by the plug. Such a cork taste can be detected from a very low harmful molecule concentration threshold of 2 ng / l (nanograms per liter).

To limit cork contamination, some cork manufacturers use oxygen peroxide H ₂ 0 ₂ , sulfamic acid or metabisulphite acid, which also has the effect of bleaching cork on the surface. Generally, the treatment of the stoppers ends with the application on the sliding agent plugs necessary for the automation of capping operations and to facilitate the extraction of the plug during the first opening of a bottle.

The so-called clogging treatment is also known in which a mixture of waxes and cork dust is applied to the stopper so as to obtain so-called "clogged" stoppers in order to be able to use a cork which is also rich in cracks. Other heavy treatments have been developed to try to eliminate the harmful molecules, the presence of harmful molecules remaining one of the concerns bottlers, bottlers and consumers.

The so-called critical CO ₂ process is known which makes it possible to obtain corks with a low content of harmful molecules. But this process says the C0 ₂ criticizes only treat cork flour, not complete stoppers. This therefore requires to perform reconstructions of corks using glues or binders. In this case, we can no longer speak of natural cork stoppers, but of technical or synthetic corks, since they contain at least as much gluing material as cork. However, even in the case of treatment with critical CO ₂ , there is still a residual rate of defects not insignificant, about 1% of bottles with a taste of cork.

There are also known treatments by superheated steam or microwaves to reduce the content of the plugs into harmful molecules. In this case, the rate of defects related to the cork taste is of the order of 3%.

All these treatments, which make the defect rate fall below 5%, require however very heavy and expensive specific equipment.

Globally, about 18 billion bottles of wine or any type of alcoholic beverage produced in 2008, about 10 billion are closed by a natural cork stopper, and it is established that about 5% of these bottles have a defect taste of cork, which represents about 500 million bottles unfit for consumption, about 375 million liters!

Numerous other treatments have been described to reduce the taste defects of cork by coating the cork stoppers to avoid direct contact of the cork with the bottled liquid.

Thus, the international application WO2007 / 115612 discloses a stopper formed from cork granules coated with a polyurethane resin.

Similarly, the international application WO97 / 30098 describes a treatment of cork with a composition comprising a diisocyanate and a diol.

Similarly, international application WO97 / 11894 discloses a process in which corks are dipped into a xylene bath and coated with a silicone rubber dispersion to form a deposit which is then fired.

Similarly, the international application WO2007 / 107209 describes a cork stopper treatment in which the corks are coated with a hydrophilic polymeric layer, such as a cellulosic layer, based on starch or alcohol polykinetic, and a hydrophobic layer, such as a layer based on a silicone derivative.

Similarly, the international application W096 / 28378 discloses a cork plug encapsulated in a layer, preferably PVC or polyurethane, formed for example by molding and heat treatment.

Similarly, international application WO91 / 04836 discloses a cork stopper treatment comprising a washing step using a solution containing sodium hydroxide, sodium silicate and hydrogen peroxide, followed by a drying step, and a third step of treatment with a solution containing acetic acid, peracetic acid and hydrogen peroxide.

Similarly, the international application WO2004 / 076607 discloses a cork plug treatment comprising forming a polyolefin layer on the plug.

Similarly, the international application WO03 / 031276 discloses a cork stopper treatment comprising the deposition of a synthetic resin powder on the cap, and the fusion of this resin by infrared heating.

PROBLEMS POSED

These problems posed by natural cork stoppers, whether they are treated in a known manner or not treated, are numerous:

a) To date, with regard to the problem of cork taste, the known systems for protecting or treating cork stoppers have proved to be either ineffective to achieve their objective, difficult or expensive to implement in the manufactures of caps.

As for the known systems for protecting the surface of the stopper in contact with the liquid, they lead to a random result with regard to the migration of harmful molecules from the stopper to the conditioned liquid, since this depends on the tightness of the plug in the neck of the bottle and possible pathways of liquid between cap and glass on untreated surfaces.

The aim of the invention is to obtain plugs that comprise an effective barrier against the migration of said harmful molecules.

The Applicant has also observed, in a test made from many types of commercial cork stoppers, that these corks, each immersed in a glass of organoleptically neutral water, were likely to give this water odors and / or taste of corks, after more than 24 hours of total immersion. This immersion in water test reveals more quickly than in wine or ethyl alcohol, a migration of harmful molecules or an alteration of taste due to caps.

b) It is known that natural cork stoppers have a permeability to oxygen and water vapor variable from one stopper to another. This great variability of permeability, this impossibility of knowing in advance the physicochemical characteristics of each stopper, is therefore a major handicap to obtain a constant quality. The aim of the invention is to produce natural cork stoppers having permeability to oxygen and water vapor within a restricted range and of a predetermined value.

c) It is known that the plugs have moisture contents that vary from one plug to another as well as over time, and this, according to many parameters, especially with ambient relative humidity or depending on whether the plug is or not in permanent contact with the bottled liquid. The moisture content inside the cork is fundamental to maintaining its physical characteristics throughout its life, until the first opening of the bottle. Variations of 3 to> 10% moisture were measured on different lots of commercial corks, before introduction into the neck of the bottles, while the standard provides for 4 to 8% moisture cork. Thus, the mechanical characteristics of compression and elastic recovery of the plugs depend for the most part on the moisture contained in the plug. The more a plug is loaded with moisture, the more it becomes flexible and its mechanical characteristics decrease, which also results in a loss of tightness, beyond a certain moisture threshold of the order of 10%. The invention therefore aims to produce natural cork stoppers having an internal humidity within a restricted range and a predetermined value. d) In a significant percentage of cases, with commercial cork stoppers, problems are encountered with the opening of the bottle and with the extraction of the cork, in particular when the bottle is uncorked, a loss of physical integrity or mechanical strength of the plug, which leads to both a difficult plug extraction - it must be done repeatedly to extract the entire neck cap - and often to contamination liquid conditioned by debris of this plug, resulting in a degradation of the quality and the drinkable quantity of the bottled liquid. The object of the invention is to obtain natural cork stoppers which retain their physical integrity, in particular during their extraction from the neck, often many years after the liquid has been packaged.

(e) The plaintiff has also observed that the values of the forces of driving and extraction of natural corks could vary for the same lot homogeneous in a ratio of 1 to 3, some values far exceeding the upper limits of the standard. This is a heterogeneity that is a serious defect.

During the extraction of known plugs, we often observe large variations in the opening effort: if too little effort can be considered as an index of poor conservation, too much effort is not acceptable either. on a practical level. It should be thought that consumers have only "average" physical strength. The invention therefore aims at obtaining natural cork stoppers which have an opening force situated in a restricted range and of predetermined value.

f) Another major disadvantage, especially with bottlers, is that of cork dust, released during the handling of corks, in the various stages of manufacturing processes, until the time of laying the cap on the bottle. Indeed, the Applicant has observed that standard commercial plugs generated cork dust in the circuits for collecting, dispensing and installing corks on the bottles. It also happens that these dusts are found inside the bottles, floating on the bottled liquid, despite the use of suction systems placed on automatic bottling machines.

g) The Applicant also observed that a large majority of standard caps were not necessarily suitable, in terms of oxygen barrier level or water vapor, for the preservation of wines, each wine requiring certain barrier level, or a barrier within a given range of values. Indeed, the aging of certain wines implies a controlled exchange of oxygen, and therefore a predetermined level of barrier. The oxygen permeability of natural cork stoppers is very random and varies from one stopper to another. For example, on a statistically representative sample of a homogeneous batch of bottles closed by natural cork stoppers, it has repeatedly appeared that the permeability values of natural cork stoppers or treated by clogging could vary from 0.0001 to 0.1227 cm. ^3/0 ₂ / 24hours per bottle (AWRI - P.Godden & Al Enoforum 2005, March 21-23, Piacenza (Italy)), a ratio of 1 to 1000, between the extremes. There can be no control over the quality of the wine under these conditions.

The invention aims to obtain plugs which have an oxygen permeability in a relatively narrow range, as already mentioned, and predetermined to be adapted to the type of liquid or wine conditioning. h) Although corking wine bottles is a constantly evolving field, the fact remains that the majority of wine bottles produced in the world are closed by a natural cork, the natural cork keeps despite its disadvantages, an excellent brand image linked to an idea of tradition. The invention aims to obtain plugs that retain the appearance of traditional natural cork stoppers.

i) In addition, having carried out bottle capping tests containing oxidation-sensitive liquids, containing effervescent drinks and bottles of pressurized beverages, the Applicant has found that the plugs of the prior art do not allow not to obtain a liquid and gaseous seal, particularly with pressures inside the container ranging from 10 bar to 15 bar, ie from 1 MPa to 1.5 MPa, for a temperature range typically ranging from 0 ° C. to 50 ° C, and this for a period of up to several years, even several decades. The plugs and treatments according to the invention aim to solve these problems.

(k) Finally, in the case of consumer products such as cork stoppers, the notion of cost of production - cost of treatment - is essential, both in terms of investment costs, productivity and costs of production. production. But it is also necessary to take into account the impact of the process on the environment, as well as the dangerousness of the process, which may require administrative authorizations, or specific investments related to safety and the protection of the environment. . The invention aims a simple treatment, economic and high productivity, and does not require special means or measures.

In general, starting from batches of so-called natural or so-called plugged plugs, the invention aims to transform any batch of corks into natural cork, with its heterogeneity and its variability of intrinsic properties, batch-to-batch variability, and the inside a same lot, in a batch of plugs with homogeneous characteristics, and low variability both from one batch to another and within the same batch.

More particularly, the invention aims to obtain plugs having properties - in particular oxygen permeability - adapted to the liquids to be packaged. DESCRIPTION OF THE INVENTION

According to the invention, the treatment of natural cork stoppers successively comprises the following steps a, c and d:

a) supplying a batch of a plurality of so-called natural plugs (900a) and impregnating said batch in a liquid composition CP (903) comprising at least one polymeric material P, at a pressure greater than atmospheric pressure P _A , way to get a so-called impregnated lot,

c) then, said impregnated batch is drained, so as to obtain a lot said wrung, d) finally, said wrung lot is subjected to a heat treatment,

so as to obtain a batch of so-called treated plugs (928), each plug (928) having a "composite skin" (204, 301, 304) of cork L impregnated with polymeric material P, represented symbolically by "L + P". According to the invention, a complementary step b) of vacuum treatment can be incorporated, the treatment of natural cork stoppers then comprising successively the following steps a) to d):

a) supplying a batch of a plurality of so-called natural corks and said batch is impregnated in a liquid CP composition comprising at least one polymeric material P under a pressure P- _\ greater than atmospheric pressure P _A, so as to obtain a so-called impregnated lot,

b) then, said impregnated batch is treated under vacuum under a pressure P ₂ <PA, so as to obtain a batch treated under vacuum,

c) then, said batch treated under vacuum is wrung out, so as to obtain a so-called wrung batch, d) finally, said wrung batch is subjected to a heat treatment,

so as to obtain a batch of so-called treated plugs, each plug having a "composite skin" of cork L impregnated with polymeric material P, represented symbolically by "L + P".

The plugs of this batch have on their entire accessible surface, outer surface and inner surface of the cavities or anfractuosities of said plugs, a surface area of cork L, comprising a penetration of said polymeric material P in its mass with an incorporation of said polymeric material P cork, so that said treated plug has the composite skin "L + P".

Thanks to this treatment according to the invention, the Applicant has succeeded in impregnating a layer of surface cork or skin with said liquid composition CP. This skin corresponds to all the accessible surfaces of the stopper and which comprise corky tissue, these accessible surfaces being:

the so-called outer surface of the stopper comprising the cylindrical surface of the stopper and the two circular faces at the ends of the stopper,

the so-called internal surface comprising all the surfaces of the cavities, cracks and any type of open crevices, that is to say opening onto said external surface.

Thus, the Applicant has found that cork, or at least its main constituent, the alveolar soft tissue, was able to absorb said CP liquid composition, as has been demonstrated in particular using micrographs with contrast agents.

However, as a natural cork is a heterogeneous material which includes, in addition to cellular honeycomb tissue that provides elasticity to the plug, portions, typically formed of other lignin and tannin-rich constituents, which may be more hard and more impermeable, including said liquid composition under pressure, a plug may therefore present locally, particularly at the level of the heterogeneities of the cork or in the anfractuosities of the plug, surface portions having a skin "L + P" of low thickness, or possibly covered with a layer of polymeric material "P".

As will become apparent in the following description and in the examples, the succession of at least steps a), c) and d) of the treatment is necessary to obtain plugs that solve all the problems posed, at least when the batch of corks stocked is a lot of so-called natural corks. In particular, it should be noted that with the naked eye, the corks obtained by the treatment according to the invention retain the general appearance of the natural cork stoppers, which would not be the case if the cork was covered with a polymeric or film-forming composition. The treatment according to the invention therefore gives the stopper a composite skin "L + P" based on cork L and polymeric material P, largely intended to be placed in contact with the neck of the container and partly in contact with the conditioned liquid. this skin forming a deformable plastic material which continues, after plugging, to marry, under the effect of the radial compression, then the elastic recovery of the cork, the relief of the inner surface of said neck. As will be seen in more detail in the following, the invention, by virtue of this succession of at least steps a), c) and d), makes it possible to solve the problems posed. Indeed, such a treatment of natural cork stoppers allows:

to considerably reduce the migration of harmful molecules from the stopper to the conditioned liquid, so as to eliminate the "taste of the stopper", the stoppers according to the invention placed in contact with a hydroalcoholic medium, do not alter its taste or the smell.

- To obtain plugs having a permeability to oxygen and water vapor within a restricted range and a predetermined value.

- to obtain plugs having a moisture content inside the plugs substantially constant from one plug to another and maintained within the range of 4 to 8% of moisture of the cork provided by the standard , so that all the plugs have the same mechanical characteristics of compression and elastic recovery, and a small loss of these mechanical characteristics over time.

- To obtain plugs that retain their physical integrity especially during their extraction of the neck, often many years after the liquid conditioning.

- To obtain plugs which have an opening force within a restricted range and a predetermined value.

- to obtain natural cork stoppers without cork dust.

- To obtain permeability plugs adapted to their particular use adapted to the type of liquid or wine conditioning.

- To obtain corks that visually retain the appearance of natural cork stoppers, both during corking and during the unblocking of the bottles, so as to convey an image of "tradition".

- To obtain plugs having a liquid and gaseous seal, and this even in the case of liquid contents under pressure.

to obtain these plugs with a particularly economical process both in investment costs, using current equipment, and operating costs, a process of high productivity and which, moreover, presents no risk to the environment, neither health risks nor any dangerousness in its implementation. DESCRIPTION OF THE FIGURES FIG. 1a is a view of a bottle neck (101) closed off by a stopper (100) and covered with an overcap (102), this view forming, on the half-right portion of the figure, a half side view, and on the half-left part of the figure, an axial half-section in the axial direction (104) of the cap and the neck.

Figures 1b and 1c are cross-sectional sections of the plug, perpendicular to its axial direction, which illustrate said composite skin (204) forming an outer composite skin (301). Figure 1b is a photograph - macrography - of this sectional portion, a black dye tracer having been incorporated in the liquid composition. Figure 1c is the schematic representation of Figure 1b.

Figures 2a to 2d are sections of plugs (100) obtained according to the invention. In order to be able to observe the impregnation of the plug in its anfractuosities or cracks, by visual or microscopic observation, a black tracer dye has been added to the liquid composition CP. It is thus very clearly perceived that the crevices such as lenticels, holes, cracks, crevices are impregnated with the liquid composition colored black so as to obtain a visual contrast.

Figure 2a is a photograph showing a left half-cut (300b) of a plug.

Figure 2b is a schematic representation of a right half-section (300a) of the plug of Figure 2a.

Figure 2c is an enlarged photograph of the framed portion A of Figure 2a. Figure 2d is a schematic representation of Figure 2c. Figure 3 is a diagram relating to plugging and plugging forces, the extraction having been performed 26 days after capping and storage at room temperature at 15 ° C.

On the abscissa are the tests E0 to E7 and the ordinate the forces in daN, the measurements being made on a sampling of 10 caps.

The E0 test corresponds to standard commercial corks made of natural cork which are not clogged and treated with silicones. Tests E1 to E7 correspond to plugs obtained with the treatment according to the invention.

Curve A: maximum extraction value

Curve B: average extraction value

Curve C: minimum extraction value

Curve D: maximum capping value Curve E: mean value in capping

Curve F: minimum capping value.

Figure 4 is a diagram of the moisture content of corks after 9 months of residence in the neck of an empty bottle and stored at 15 ° C.

On the abscissa are the tests E0 to E7 and the ordinate humidity in%, the measurements having been carried out on a sampling of 10 stoppers.

Curve A: maximum value

Curve B: average value

Curve C: minimum value

FIG. 5 schematically represents, in axial section, the device used for measuring the oxygen permeability of a bottle portion (600) provided with the plug (100) to be tested. This bottle portion (600) is secured to a metal platen (611) by a bead (612), the platen being provided with gas supply tubes (613) and gas outlet tubes (614), a sealed envelope (610) covering said bottle portion (600).

FIG. 6 schematically represents a first device modality for the implementation of steps a) to d) of the object of the invention.

FIGS. 7a to 9c illustrate another device modality for the implementation of steps a) to d) of the object of the invention. In this modality, all the steps of the treatment are carried out, without transfer of the plugs, in a wiper reactor (800).

Figures 7a to 8b are cross sections along the plane C-C of Figure 9c.

FIG. 7a illustrates the step a) of impregnation under pressure.

Fig. 7b illustrates step b) vacuum desorption processing.

Figure 8a illustrates the step c) of spinning.

Figure 8b illustrates step d) of drying.

Figures 9a to 9c are longitudinal sections along the axis or central shaft (803,

803 ') and according to the plane A-A of FIG. 7a, which illustrate different variants of wiper reactors (800).

FIG. 9a represents a wiper reactor (800, 800a) of spherical shape.

Figure 9b shows a wiper reactor (800, 800b) of cylindrical shape.

FIG. 9c represents a wiper reactor (800, 800c) of bi-frustoconical shape. DETAILED DESCRIPTION OF THE INVENTION

In the treatment according to the invention, in step a) of said treatment, said batch of plugs (900a) can be immersed in a first pressure-resistant container (902) containing said liquid composition (903), and said container (902) under pressure with an air pressure P of between 2 and 6 bar and preferably of 3 to 5 bar, said air pressure P † being applied inside said first container (902) over a period of time between 1 and 15 minutes and preferably from 3 to 10 minutes.

With regard to step a) impregnation, and after having tested several coating application methods, such as brush removal, spray spraying, dipping, soaking under ultrasound, it appeared to the plaintiff that these methods did not solve the problems posed. These problems were only solved when the treatment included a pressure impregnation of the polymeric CP liquid composition allowing this liquid composition CP to penetrate homogeneously inside the structure of the cork, in the cracks, the craters, slots, and galleries created by insects, or other open crevices opening on the surface of the plug. However, as can be seen in FIGS. 2a and 2b, it seems that, during step a) of impregnation under pressure, almost all the anfractuosities are impregnated with said liquid composition CP, even in the case crevices or cracks not directly open. It therefore seems that the pressure used in step a) of the treatment makes it possible to introduce said liquid composition CP into the entire network of crevices or crevices of the plug.

The Applicant has thus observed that at ambient temperature, using the film-forming or polymeric coating with a colored tracer, and for example applying a pressure of 5 bar for 3 minutes or 3 bar for 5 minutes, the penetration goal was totally achieved.

The same tests were carried out under different pressures at temperatures ranging between 20 ° C and 38 ° C, without observing significant variations in the results. However, the viscosity of the polymer coating decreasing as a function of the rise in temperature, it was found that the duration of the impregnation under pressure could be decreased in the ratio of the lowering of the viscosity ratio. Thus, preferably, and also to overcome external temperature variations, it will be preferable to operate to perform the impregnation under pressure at a relatively constant temperature of 38 ° C ± 2 ° C. Moreover, the Applicant has also observed in his experiments, that a sudden setting off pressure, favored the desorption of surplus CP liquid composition.

Thus, and as can be seen in FIG. 6, a batch of raw corks (900) previously packaged in a suitable net (901) whose mesh size does not exceed the smallest size of the corks to be treated is introduced into a pressure-resistant reactor or tank (902) inside which the CP liquid composition (903), typically comprising an aqueous aqueous acrylic polymer emulsion or an aqueous EVOH-based composition, has previously been introduced. copolymer of ethylene and vinyl alcohol.

The batch of caps must be completely immersed in the liquid composition (903), then the lid (904) of said tank will be hermetically sealed. An overpressure of filtered and controlled air (905) is then applied inside the tank (902). The reservoir (902) is temperature controlled so as to maintain the viscosity of the liquid composition (903) constant. The pressure is then suddenly relaxed inside the tank (902) and the lid (904) is removed. The net (901) is raised above the level of the liquid composition (903) and allowed to drain for a few moments.

At the end of this first impregnation step, and before proceeding to the next step, it has been observed that a step of draining the plugs made it possible to save a significant amount of the liquid composition (903). . Thus a dewatering time of the order of one to two minutes, accompanied by shaking saves about 5 to 20% of the amount of liquid composition (903). Thus, any loss of liquid composition is otherwise avoided at least very limited.

The applicant has observed that the amount of CP liquid composition consumed could vary according to various parameters, such as the surface tension of the plugs, the viscosity of the liquid composition CP and therefore its temperature, but also the quality of the plugs. Thus it has been observed that "0" quality corks (superior quality called "Super") without slots or craters or galleries, consumed much less polymeric material, than lower quality corks, for example, quality 3 or beyond, these being dotted with holes, craters, slots and galleries for storing a greater amount of liquid composition CP (903) and polymeric material P. As will be indicated later, the treatment according to the invention can also be used with so-called plugged plugs, typically formed from plugs of grade 3 or beyond. In this case, the anfractuosities and cracks of the plug being already clogged, the consumption of liquid composition will be even more reduced.

In the optional step b) of the treatment, said impregnated batch can be treated under vacuum, inside a vacuum-resistant container (902 '), with a pressure P ₂ ranging from 0.1 to 4 mbar. and preferably from 0.5 to 1.5 millibar.

Said vacuum may be made inside said container for at least one minute, and preferably in cycles, with the atmospheric pressure being restored between each cycle, the number of cycles ranging from 1 to 10, and preferably ranging from 3 to 7, each cycle comprising a vacuum phase for about one minute.

In the case of a batch of so-called natural corks, the Applicant has found that this vacuum desorption step was necessary. Indeed, in the absence of desorption under vacuum, the Applicant has observed the formation of bubbles or microbubbles on the surface of the plug at the time of step d) of drying and baking of the polymeric material P, which adversely affects both the technical quality of the cap, and its appearance and aesthetics. The Applicant has assumed that the vacuum treatment makes it possible to expel small crevices or cracks an excess of CP liquid composition that the spinning, in step c) of the treatment, would not eliminate.

The desorption operation of step b) is produced by the depression of the reservoir containing the batch of plugs to be desorbed. Typically, the tests have shown that a pressure P ₂ of 4 mbar can be used per cycle of one minute. The Applicant has observed that several alternating cycles of evacuation and relaxation, significantly increased the desorption level. Thus, series of 3 to 5 alternating cycles of evacuation for 1 min and relaxations gave excellent results. The conditions of this desorption are such that this desorption affects only the liquid composition CP "free" which is in the crevices, and not the liquid composition that has penetrated into the cork to form said composite skin "L + P".

In step c) of the treatment, after venting, the batch of vacuum treated plugs can be, once introduced inside a wringer (910), wrung out in cycles, each cycle comprising a spinning phase lasting from 0.5 to 5 minutes, preferably between 1 and 3 minutes, with a number of cycles of between 1 and 5 and preferably between 2 and 3, a phase of stirring plugs being interposed between each phase spin, lasting between 3 seconds and 1 minute and preferably between 5 seconds and 30 seconds, and during which the plugs change position and place inside the drum of the wringer (910).

Typically, the batch of plugs can be subjected to a centrifugal force of between 20 and 80 Newtons, preferably between 30 and 60 Newtons.

The Applicant has observed that this dewatering step c), before the firing of the coating, was necessary to complete or supplement the desorption step b), in order to avoid the excess of polymeric emulsion in the anfractuosities of the plugs, causing lingering bubbles after cooking. In addition to the unsightly appearance of these bubbles, they are torn during handling, distribution and installation of plugs thus releasing into the air cork particles may redeposit on different equipment and possibly in the bottled liquid. Likewise, the spin eliminates the presence of agglomerates of liquid composition CP on the surface of the stopper. All the stoppers of a lot having undergone the stages of pressurization and then of evacuation, followed by spinning, respecting the cycles tested by the Applicant, have an absolutely clean outer surface and free of any visible surface defects. with the naked eye, any mass of CP liquid composition or polymeric material P.

The spin can be practiced in a drum machine with vertical or horizontal axis. Horizontal axis machines will be preferred because of the possible brewing steps between two spin sessions. These stirrings allow the plugs to move to provide different angles of extraction of coating product and thus to homogenize this operation.

The Applicant has shown that the choice of a drum machine with a diameter of 450 to 500 mm for a range of rotation speeds of 1200 to 1500 revolutions per minute made it possible to solve the problem posed, provided that cycles were observed. brewing at low speed: about 60 rpm. Preferably, alternating stirring with inversion of the direction of rotation, and spin.

When a net is used to contain a batch of stoppers, the applicant has shown that the plugs could be introduced into the drum of the wringer, pre-packed in the net already used during the dipping-impregnation and desorption, said net, typically meshes of the order of 10x10mm having a global volume slightly greater than that of the drum of the wringer, so as not to thwart the effects of centrifugal force during the spin cycles. In step d) of the treatment, after having extracted the batch of plugs (921) from the wringer (910) in step c) of the treatment, said batch of plugs (921) can be treated in a chamber ( 920), by a flow of hot air at a rate between 3.0 and 20.0 meters per second and preferably between 5.0 and 10.0 meters per second, so as to form said heat treatment, said treatment thermal being intended in particular to remove a solvent from said liquid composition CP, when said liquid composition CP comprises a solvent.

At the end of step d) of the treatment, the batch of cap can be cooled by a flow of cold air, and possibly the speed of said cold air flow can be increased beyond 15 m / s, so as to expel said batch of caps from said enclosure, and thus to collect the batch of plugs directly into a bag or container adapted for this purpose.

Said flow of hot air may be applied at a temperature between 80 and 120 ° C and preferably between 90 and 100 ° C for a period of between 3 and 15 minutes and preferably between 5 and 10 minutes.

However, as a first step, said flow of hot air may be applied at a temperature of between 40 and 80 ° C. and preferably between 50 and 70 ° C. for a duration of between 1 and 10 minutes and preferably between 2 and 5 minutes.

Preferably, after having applied said flow of hot air, the heating of said flow of hot air can be stopped, said flow of air then passing at ambient temperature, so as to cool at ambient temperature said batch of plug, while a time substantially equivalent to that of said heat treatment.

After having tested various processes, such as the traditional oven ventilated, the microwaves, it appeared to the applicant that during the operation of evaporation of the solvent phase and the polymerization of the coating, the caps should not, preferably, remain in static contact with a wall, so as to obtain plugs having an excellent appearance of traditional plug and avoid the presence of visible marks on the plugs.

The Applicant has developed a drying-baking system as illustrated in FIG. 6. After various tests and a development phase, the solution of the levitation of the plugs under hot air flow was found to be excellent for obtaining plugs without surface defects.

The polymeric emulsion in aqueous phase forming said liquid composition requires a phase of evaporation of the solvent. When the solvent in question is water, which is the preferred case, the water must be evaporated, before coagulation and polymerization of the coating, otherwise bubble formation would be observed. The following Time / Temperature cycle will be preferred:

1 - 40 to 60 ° C for 2 to 3 minutes

2 - 70 to 120 ° C for 3 to 15 minutes, and preferably 80 to 90 ° C for 5 minutes, then cooling to room temperature for an equivalent period.

At the end of step d) of the treatment, the plug batch can be cooled by a flow of cold air velocity, and possibly the speed of said cold air flow can then be increased beyond 15 m / s, so as to expel said batch of plugs from said enclosure, and thus to collect the batch of plugs directly into a bag or container adapted for this purpose.

According to another modality of the treatment according to the invention, in step a) of the treatment, it is possible to supply a batch of so-called plugged plugs, and the step b) of evacuation can be eliminated. Indeed, the invention applies to all types of plugs. For obvious economic reasons, it will be preferable to use it with types of caps of relatively economic cost, which is the case of so-called natural plugs. But so-called plugged plugs are also of a substantially similar cost insofar as the additional cost due to clogging treatment is substantially balanced by the lower cost of the starting cork, the latter, of lower quality, having more crevices or cracks, whether in number or depth.

Since the cracks have been clogged beforehand, the desorption step b) plugs can thus be suppressed, having no reason to be. Advantageously, the fluids used at the different stages of said treatment, whether in particular the compressed air in step a) of the treatment, or of the hot air in step d) of the treatment, must be neutral. and free of germs, bacteria, yeasts and all contaminating sources of pollution for the liquids closed by the corks thus treated.

In the treatment according to the invention, said liquid composition CP (903) may comprise, in addition to said polymeric material P, at least one additive A intended to promote the sliding of the stopper in contact with the glass, so that said treated stopper a "skin" of composition symbolically represented by "L + P + A". In the treatment according to the invention, said liquid composition CP (903) can form an emulsion or a dispersion in aqueous phase of at least one polymeric material P chosen from polymeric materials:

a) approved for food contact,

b) capable of forming a barrier to said harmful molecules,

said polymeric material P preferably being an acrylic polymer emulsion in an aqueous medium or an aqueous EVOH-based composition, a copolymer of ethylene and vinyl alcohol. According to another embodiment of the invention, said treatment may comprise:

a) a said first succession of at least steps a), c) and d), from a said first polymer liquid composition CPi, typically formed by the said liquid composition CP comprising the said polymeric material P, so as to form a said first impregnation,

b) and a complementary treatment comprising, for example, a said second succession of at least steps a), c) and d), from a said second polymeric liquid composition CP ₂ , at least the said second liquid polymer composition CP ₂ comprising said additive A intended to promote the sliding of said plugs, so as to form a said second impregnation, so that said treated plug has a composite "skin" of composition symbolically represented by "L + P / A".

Said first and second polymeric compositions may be different, and for example, only the second impregnation may comprise said additive A.

It has not yet been possible to establish precisely whether the second impregnation is superimposed and / or whether it is mixed with the first impregnation.

Said liquid composition CP (903), CPi or CP ₂ can comprise an elastomeric material E chosen from: butyl rubber, nitrile rubber, thermoplastic elastomers such as SIS (styrene isoprene styrene), SBS (styrene butadiene styrene), SEBS (Ethylene styrene butylene styrene), MS Polymer (Modified Silicon Polymer) or PDMS (Polydimethylsiloxane).

Said additive A intended to promote the sliding of the plug in contact with the glass may be an anionic emulsion wax, typically based on paraffin wax or carnauba wax or a silicone resin when said first liquid polymer composition CP _! comprises said aqueous composition based on EVOH, in order to cover said EVOH-based polymeric material P with a layer forming both a water barrier and a slip agent, said additive A being able to be an additive A ₂ constituting said second liquid polymer composition CP ₂ said second polymeric liquid composition then being free of EVOH.

Said liquid composition CP (903) may comprise a micronized mineral filler B forming a barrier, in particular to the diffusion of gases, said inorganic filler being chosen from: silica SiO ₂ , a silicon oxide SiO _x (with x <2), TiO ₂ titanium oxide, micronized clay, kaolin, barium sulfate.

In step a) of the treatment according to the invention, said liquid composition CP (903) can have a dynamic viscosity at 20 ° C of between 5 and 1000 cps (centipoise), and preferably between 10 and 800 cps, of in such a way that said CP liquid composition (903) can penetrate the crevices of the natural cork stoppers and form said skin or said composite skin. In an advantageous embodiment, said dynamic viscosity is between 5 and 100 cps, and preferably between 10 and 40 cps.

Advantageously, at least during steps a) and b) of the treatment according to the invention, and according to the technical modalities of implementation of the treatment according to the invention, and in the case of the process as illustrated in FIG. 6 said batch of plugs may be contained in a mesh of chemical nature and of mesh size (for example 10 mm × 10 mm) adapted, capable of passing said liquid composition CP (903) while remaining inert with respect to said liquid composition, and with a mesh size smaller than the smallest dimension of the corks to be treated, so as to have to manipulate a net in which is located said batch of corks, during steps a) to c) of treatment.

Another object of the invention is constituted by a cork, typically a batch of corks, obtained by the treatment according to the invention, and characterized in that it has on its entire accessible surface, outer surface and surface internal cavity or crevice said plugs, a cork surface area L, comprising a penetration of said polymeric material P in its mass with an incorporation of said polymer material P cork, so that said treated plug has a composite skin (204); , 301, 304) of composition symbolically represented by "L + P", said composite skin (204, 301, 304) having a thickness E of at least 10 m and up to 1 mm, depending on the local hardness or porosity of the natural cork or its constituents.

Typically, said polymeric material P may be an acrylic resin with a density of between 0.95 and 1, 2, and preferably between 0.98 and 1 00, or an aqueous composition based on EVOH, an ethylene copolymer and polyvinyl alcohol.

As already indicated, the presence of a "L + P" composite skin is not exclusive of the possibility of having at least locally a part of said polymeric material P deposited on the surface of the cork, in particular within the crevices. of the cap. According to the invention, said surface area of cork L forming said composite skin (204, 301, 304) can comprise, in addition to the incorporation of said polymeric material P cork, the incorporation of said additive A intended to promote the sliding of the cork in contact with the glass, so that said treated plug has a composite skin of composition symbolically represented by "L + P + A" or "L + P / A" according to whether said additive A is incorporated in said polymeric material P or covers said polymeric material P.

Said surface area of cork L may comprise, in addition to the incorporation of said polymeric material P to the cork and the incorporation of said additive A, the incorporation of at least one adjuvant chosen from: a micronized mineral filler B forming a barrier, in particular to the diffusion of gases, an elastomeric resin E.

Another object of the invention is the use of corks according to the invention, or obtained by the treatment according to the invention, for sealing containers, typically made of glass, containing alcohols, wines or spirits.

DESCRIPTION OF EXAMPLES

A) Starting materials selected for testing:

A1) Cork corks: A supply of untreated corks has been supplied to natural cork processors: these plugs, known as natural corks, have not undergone any treatment other than washing with hot water, are called natural. These natural cork stoppers are of standard dimensions 45mmx24mm (height x diameter).

In addition, we have also supplied lots of corks plugged.

A2) Liquid compositions comprising a film-forming or polymeric material A liquid composition comprising said polymeric material P selected among the materials approved for food contact has been selected and supplied:

A20 = Michem Coat ™ MC40EAF-E from Michelman Inc.

A21 = VaporCoat ™ 2200 ^e from Michelman Inc.

These are dispersions of acrylic resins in aqueous emulsion.

These two materials were selected after testing with a large number of materials suitable for food contact.

However, comparative test batteries have made it possible to demonstrate a better match of the Vaporcoat ™ 2200 ^e to the problem posed. The physico-chemical characteristics of the MC40EAF-E do not allow it to be applied at room temperature in a simple process. It is necessary to apply high pressures, greater than or equal to 5 bar at least 38 ° C and longer durations, greater than 5 minutes, to obtain correct results.

The Applicant has therefore selected the Vaporcoat ™ 2200 ^e as polymeric liquid composition CP to prepare and test the plugs according to the invention.

In addition, a liquid composition comprising said polymeric material P selected among the materials approved for food contact, a Kuraray EVOH composition, reference AQ-4104, was selected and supplied under reference A22.

A3) Additives A intended to promote the sliding of the cap in contact with the glass:

A30 = ML160PFHS.E by Michelman Inc. (Carnauba Wax Emulsion)

A31 = ML723HSA-E from Michelman Inc. (Paraffin emulsion).

Selection of these additives: slip tests on glass, as well as full-length tests on plugs, with statistically representative series, have shown that Vaporcoat 2200 ^e poses a problem of adhesion to glass , to the point that the driving and extraction efforts found some values very outside the higher ranges of the standards in force. Many additives have been tested and two of them (A30 and A31) have been selected to carry out comparative tests compared to the reference products, which are the natural cork stoppers.

A4) Mineral fillers B intended to form a barrier to gases:

The following commercial products have been supplied: silica SiO ₂ , talc, ...

A5) Other raw materials: Silicone and synthetic rubber-based elastomer dispersions, in particular a Bluestar silicone-based dispersion, reference CAF 72582. Provided with reference A50. B) Equipment for the implementation of the treatment according to the invention

The various tests carried out implemented the treatment of the invention, as shown diagrammatically in FIG.

For this, we supply or manufacture the various necessary equipment E, namely:

B1- A first container (902) adapted to hold at a pressure of 5 bar, with a capacity of 20 I, provided with a removable cover (904) equipped with a pressure gauge (905) and an inlet of pressurized air.

B2- A second container (902 '), of substantially the same capacity as the first container (902), able to hold a vacuum, namely at a residual pressure of 0.1 millibar, said second container (902') being provided with a removable cover (904 ') with a vacuum gauge (905') and a vacuum plug connected to a vacuum pump.

B3- A wringer (910) with a variable speed drum, and a pump for extracting the recovered film-forming liquid composition.

B4- A drying device comprising:

- a vertical drying column forming a cylindrical tube (920), adapted to be supplied with air (hot or cold) at its lower part, and comprising:

at its lower part, a perforated lower grid (924) forming a support for the batch of plugs to be dried,

^* at its upper end, a removable perforated upper grid (925) so as to let the hot or cold air, but to retain the plugs in the cylindrical vertical enclosure (920),

* at its upper part - just below said upper end - an upper lateral tubular duct (927) opening into said vertical enclosure through an opening, adapted to be held closed or opened by a movable flap (926), allowing the transfer of the caps to a packaging means, such as a net (929).

a turbine (922) for propelling air into a lower lateral duct,

an air heating means, such as electric heating resistors (923).

B5- Centralized control means of these equipments, with recording of the parameters. These means have not been shown in FIG. B6 - A plug retention net capable of holding 100 caps per test. All equipment has been supplied commercially, with the exception of the B4 drying device which has been designed and constructed in the context of the invention. Tests have also been carried out with a single-vessel device, as shown in FIGS. 7a to 9c, which makes it possible to carry out the four stages a) to d) of the treatment in the same reactor.

C) Generic implementation of steps a), b), c) and d) of treatment

C1 - Step a) impregnation under pressure

In an autoclave or reactor vessel, a batch (900) of 100 so-called natural cork stoppers, namely crudes from a cork, is introduced into a suitable net (901) whose mesh size does not exceed the smallest size of the corks. washing, and a liquid composition CP (903) forming a bath, as represented in step 1 of FIG. 6, so that the plugs are totally immersed in the liquid CP composition in aqueous phase. After closing the lid (904), there was applied to the interior of the container a filtered and controlled air overpressure (905) of 3 bar (1 bar is 10 ⁵ Pa) for 5 minutes. At the end of this time, the compressed air was turned off and the inside of the vessel was allowed to return to atmospheric pressure. After having removed the lid (904), the net (901) was raised above the bath formed by the liquid composition (903), so that fillet and batch of plugs (900) drip for two minutes. minutes, so as to recover the excess of said liquid composition CP.

Note that the autoclave container was self-regulated in temperature around 38 ° C so as to maintain the viscosity of the liquid composition CP constant.

C2- Step b) vacuum desorption treatment

The batch of plugs (900) from impregnation stage a), still packaged in the net (901), was introduced into a second reservoir or reactor (902 ') resistant to depression, and then the lid (904). ') of said tank has been hermetically sealed. The inside of the tank was evacuated with a pressure controlled by a vacuum meter (905 ') of 1 millibar for 1 minute. Then the vacuum was turned off and this second tank (902 ') was put back to atmospheric pressure. This cycle was repeated 5 times. Then the lid (904 ') was removed and said batch of plugs (900') was removed from said second tank (902 '). The desorbed CP liquid composition (906) was recovered at the bottom of the tank (902 '). This small amount (906) of said CP liquid composition was extracted, either by gravity or with a pump, to then be filtered and recycled in the first step a) pressure impregnation. C3- Step c) spinning

The batch of plugs impregnated with the emulsion polymers, still inside the net (901), was introduced inside a wringer (910) through the access window (911). The batch of plugs (900 ') was then subjected to alternating cycles of spinning and stirring, the net being of a volume slightly greater than that of the drum of the wringer. In the inner tub of the wringer, the polymer exudates which have been pumped back by the pump (912) were recovered to a recovery tank, to be filtered and recycled into the impregnation circuit.

C4-Stage of heat treatment (drying - cooking)

The batch of corks was extracted from the wringer directly with the aid of the net (901). The plugs were dumped from the net directly into a highly ventilated vertical duct furnace (920). The plugs were held by a calibrated wire mesh (924) above the low temperature heating system (923). The heating was increased to its set point and a vertical hot air stream ("A" circuit), from bottom to top, was circulated with a flow rate or flow rate that was high enough to maintain the plugs (921). levitation or suspension in the air. A second calibrated grid (925) in the upper part of the duct, retained any plugs lighter than the average of the batch, and under the upward pressure, would have risked escaping from the duct (920). The heating (923) was raised to its nominal level after a first solvent evaporation step. The plugs have been maintained in a levitation or flotation state in order to avoid the sticking effects between them, but also to avoid any excessive contact against the wall of the vertical duct (920). Advantageously, the walls of the vertical duct (920) have been surface-treated with PTFE deposition or any other material promoting sliding and limiting the risk of material accumulation of the coating object of the invention. When the heating cycle was completed, according to the times and temperatures, the air heating was stopped, so that fresh air was circulated instead of hot air, which allowed the batch of plugs (921) to cool to a temperature close to room temperature.

The air velocity has been lowered, for example to around 3 m / s, in order to force all the plugs to go down to the lower grid (924) and thus to allowing the flap (926) to move to obstruct the vertical duct (920) without being obstructed by possible levitation plugs and thus open the horizontal duct (927).

A drying cycle comprises the following steps A to F:

A - stabilization of the installation at temperature and air velocity at around 3 m / s.

B - Introduction of a lot of plug in the vertical chimney previously opened.

C- Blanking of the plug introduction port with a retention grid of calibrated section, so as not to introduce losses of charges.

D - Adjustment of the speed of the air between 5 and 10m / s, according to the size and mass of the caps, so that they remain in levitation or floating in the volume of the chimney, and to avoid the contacts with the walls and gates shutter ducts.

E - Switching off the heating and introducing fresh air for the same duration.

F - Reduction of air velocity to around 3 m / s

But the procedure chosen for the tests was the following for:

a first solvent evaporation cycle with an air temperature of 50 ° C. ± 10 ° C. (in some embodiments, this temperature may range up to 70 ° C. ± 10 ° C.), but which does not comprise not the E & F steps,

a second cycle comprising an elevation of the heating temperature, with an air temperature of 80 ° C. ± 10 ° C. (In some embodiments, this temperature can range up to 90 ° C. ± 10 ° C. - Expulsion of corks and packaging

When the temperature of the treated and polymerized plugs has reached substantially the ambient temperature level, the batch of said plugs is expelled to the outside of the vertical oven, via a movable flap (926) closing off the main vertical duct , to direct them towards the exit through the horizontal duct thus released, with a speed of expulsion for example of 10 m / s. The plugs (928) are collected in an intermediate packing net (929), or in their final packaging.

The applicant was able to observe that it was necessary to comply with strict hygiene rules, in order to avoid any accidental pollution, whatever their origin, during this treatment cycle. In fact, the materials, equipment, tools and fluids used must remain under constant physico-chemical control, plus especially ensure the absence of bacteria, germs, to avoid any risk of contamination and cause organoleptic drift, or chemical changes of the bottled product.

In addition, the final packaging is advantageously made out of dust so as not to introduce external dust into the plugs conditioned for their end use.

D) The different tests carried out

Numerous exploratory tests have been carried out by the Applicant both with regard to the chemical nature of the starting CP liquid composition (903), as well as the process parameters for applying these compositions (903).

By way of information, the applicant has carried out the following tests which show, in the case of a supply of so-called natural corks, the necessity, according to the case, of the three stages of the treatment according to the invention (a, c and d of the process noted PR2), or of the four steps (a, b, c and d of the process noted PR1), with, in the following table, "1" if the corresponding step has been implemented, and " 0 "otherwise:

^* The plugs were impregnated without pressure.

** By cons, as already mentioned, especially in the case where supplying a batch of so-called plugged plugs, step b) vacuum desorption is no longer necessary to obtain plugs according to the invention. D1 Tests relating to the liquid composition with the same treatment

Various liquid compositions CP (903) were prepared by mixing a composition or polymeric material P in the form of an aqueous dispersion, and a slip agent A, also in the form of an aqueous dispersion.

For each test, the nature and weight percentage of constituents P and A were indicated.

Many other additional tests have been carried out.

Thus, the E7 test was also carried out from a batch of so-called plugged plugs, according to the PR2 method.

Similarly, the test E1 was also performed by supplementing it with a subsequent application of a slip agent, which may correspond to the products A30, A31 or possibly A50.

Similarly, plugs with two impregnations were produced, a first with a liquid composition CP-i comprising 80% by weight of A21 and 20% of a barrier inorganic filler, and a second with a liquid composition CP ₂ comprising 80% by weight. by weight of A21 and 20% of A3.

Similarly, plugs with two impregnations were produced, a first one with a liquid composition CP 2 comprising 80% by weight of A 21 and 20% of a mineral barrier filler, and a second with a liquid composition CP ₂ comprising 60% by weight. weight of A21, 20% of A31 and 20% of a dispersion of an elastomer.

In the treatments comprising two impregnations, each of these impregnations can be carried out according to the method PR1 and / or PR2, with all the possible combinations: PR1-PR1, PR2-PR2, PR1-PR2, PR2-PR1; "PR2-PR1" meaning that the first impregnation is carried out according to the method PR2 which does not comprise step b) vacuum treatment, while the second impregnation is carried out according to the method PR1 which itself comprises one.

Likewise, plugs were made with impregnation with a liquid composition CP comprising the Kuraray EVOH composition A22, reference AQ-4104, using each of the PR1 or PR2 method, said impregnation being followed by an application of at least one layer, and preferably two layers, of a Bluestar Silicone Fluid Dispersion A50, reference CAF 72582, said application being followed by drying under pulsed air flow, the Applicant having observed that it was thus possible to advantageously obtain a silicone resin-based outer layer forming both a moisture barrier to protect the underlying moisture-sensitive EVOH layer, and a slip agent for cap. E) Results obtained:

It should be noted that since the additional tests led to results comparable to the best results of tests E1 to E7, these results were not mentioned below. 1 - Visual aspect:

On the one hand, all the plugs of the same batch have a great homogeneity, and visual inspection of the same plug attestste that the composite skin formed on the surface of the plug is perfectly regular, taking into account the texture specific to the natural cork as a support, and gives the cork a natural cork appearance.

On the other hand, the sections of these plugs, as illustrated in FIGS. 2a to 2d, have shown, by using a colored contrast agent, on the one hand, an excellent penetration of the film-forming liquid composition into the crevices of the cork. and, on the other hand, the formation of a "L + P" composite skin on the surface of the cork plug suberous tissue, as shown in Figures 1b and 1c.

2 - Clogging and extraction force

Bottles have been closed with the plugs of the previous tests, using the usual method: using an instrumented commercial device to measure the vertical force, the plug is compressed radially and then introduced by mechanical push vertical in the neck of a bottle. After storage for 26 days at 15 ° C, the caps were extracted with a device to measure the extraction effort.

The results of these tests are summarized in the table in Figure 3:

with regard to the vertical corking force, it is possible to observe a smaller dispersion of the forces with the plugs of the tests E1 to E7 according to the invention compared to the control test E0, as can be seen by observing the difference between the curves D and F of the maximum and minimum values. The average values, which are substantially around 30 daN for the E0 test, fall quite significantly below for a number of tests according to the invention, for example the tests E3 to E6. - As regards the effort of extraction plugs, we can note, on the one hand a big difference depending on the nature of the sliding agent A: the results are significantly higher with the sliding agent A31. Note the results of the E7 test, remarkable both by the low dispersion of effort values both in capping and extraction, and by the level of these efforts, ideally located between 20 and 30 daN. On the other hand, corks of commercial natural cork of length 45mm x 24mm in diameter, treated with silicones, gave ranges of values at the vertical clamping force of between 28 and 50 daN on collars of bottles, dry glass. The dimensions and profiles of bottle necks were previously measured as sweeping the tolerance spectrum of CEN standards EN12726: 2000, GME 30 .05 and NF H35-100TR.

The plugs from the same batch were treated as the E7 test, and the results obtained with these plugs on the same bottles as before, gave ranges of values at the depression between 25 and 30 daN perfectly centered and with a standard deviation of 2.19, compared with a standard deviation of 11.71 in the case of commercial plugs (test E0).

Concerning the extraction effort values, these were measured 26 days after capping, still on the same batch of labeled bottles.

The commercially treated natural cork bottles 45 x 24mm treated with silicones (test E0) have extraction values ranging from 20 to 30 daN with a standard deviation of 3.90, which is already remarkable because it is not rare to find on the market extraction values on natural cork fluctuating between 10 and 50 daN and even from 30 daN to more than 60 daN in the case of plugged corks.

In the case of the E7 test, the extraction values range from 23 to 30 daN with a relatively low standard deviation of 2.19. 3 - Dusts of plugs

At the end of the treatment according to the invention and the different subsequent capping and extraction operations, no trace of cork dust appeared, whereas under the usual conditions of use of natural corks treated paraffin or silicones or with the technical caps, significant amounts of cork dust are formed on the bottling lines, especially during the distribution and installation of said plugs.

The plaintiff has carried out the test recommended in the Charter of Corkers Corkers, carried out on 4 caps taken at random, on a lot. This Charter recommends that the amount of dust must be less than 1, 5 mg for plugs in higher range and 2 mg for plugs in standard range. It has been found that with the plugs according to the invention, the amount of dust deposited is almost zero, and in any case at least ten times less than in the case of control plugs (test E0).

4 - Moisture content of corks

The Applicant has checked the internal hygrometry of the plugs obtained in the tests according to the invention, as well as the hygrometry at the start. All the caps of the tests have moisture content values, measured at 20 ° C, between 4 and 5%, values substantially identical to those of the initial plugs.

The plugs of the control test E0 also have a humidity level in the same range of values.

In addition, two types of tests were performed:

4A) Open air test:

The batches that were used for the sinking and extraction tests were taken back and measured after 9 months of storage in the corker's original packaging. Note that these plugs all include the insertion hole of the twist of the corkscrew used during the extraction tests. The presence of this hole is a difference attenuator between the lots "A" natural cork trade and "B" impregnated with the treatment product of the invention.

The results have been collated in the table of Figure 4.

The commercial natural cork stoppers, treated with silicones (E0), had an average humidity measured at the beginning of 4.4%, and a mean humidity, measured after 9 months, of 5.5%. Commercial natural cork stoppers treated according to the invention (tests E1 to E7) had an average humidity initially measured after impregnation of 5.2%, and after 9 months, this average humidity was still 5.2%.

In view of this first series of results, it is clear that, unlike commercial natural cork stoppers, the corks treated according to the invention have absolutely not changed over time, despite the presence of the hole. spin at their upper end.

4B - Total immersion test

The two batches of test plugs E0 to E7 were immersed for 24 hours in a container containing water from the network. At the end of this period, and after a drying time of 24 hours in the open air, a new series of measurements was carried out and the following results appeared:

Commercial natural cork stoppers treated with silicones (test E0) had a moisture content initially measured ranging from 4.6 to 5.8% moisture. After immersion and drying, after 48 hours, the measured average humidity increased from 6.6% to 9.6% moisture.

The plugs of the tests E1 to E7 which are the subject of the invention had a humidity measured initially ranging from 4.7 to 5.4% of moisture. After immersion and drying, after 48 hours the measured average humidity ranged from 5.0 to 5.2% moisture. In view of these results, the applicant notes that, unlike standard commercial plugs, corks treated according to his invention do not evolve over time, even in the presence of a liquid. The Applicant has concluded that the corks treated according to his invention can equip coated or uncoated bottles, which is not the case for standard commercial bottles, they must not under any circumstances remain upright, since said plugs must keep in constant contact with the liquid, otherwise the cork loses its moisture, becomes hardened and loses its elasticity, resulting in a loss of watertightness due to lack of contact force or springback, inside the cervix. the bottle. 5 - Permeability to oxygen

The sealing of a stopper does not only depend on the intrinsic barrier properties of the cork in contact with the interior of a glass tube. It is imperative to use a test representative of the actual sealing conditions of clogged bottlenecks. For this reason, the Applicant has used the following leak test (see FIG. 5): a) a corked bottle is supplied with a natural cork stopper and the bottle body is cut so as to remove its lower part. The cut should be as clean and as flat as possible so that the top of the bottle (601) with its stopper (600) can be placed on a flat plate (611), typically made of stainless steel, in an area where it is perforated for pass two ducts (613) and (614). The connection between the bottom end of the bottle and the stainless steel plate (601) is made perfectly tight by depositing a bead (612) thick (typically 20 to 30 mm) of epoxy resin. Through the conduit (613) is introduced into the bottle of a purity controlled gas, typically pure argon or pure nitrogen. This gas is evacuated via the conduit (614) which is connected to a means making it possible to measure the quantity of foreign atoms (for example oxygen atoms) which have been introduced inside the bottle (Oxtran type machines ). The assembly is placed under a chamber (610), and the latter is filled with oxygen. To properly assess the tightness of the closure, it is necessary to wait several tens of days, before starting to measure the amount of oxygen that has infiltrated the inside of the bottle.

The applicant has carried out comparative tests of oxygen permeability of corks on bottles, in marketing conditions, which means with liquid inside said bottles. One batch of bottles was capped with standard commercial 45 x 24mm silicone-treated plugs (E0 test) and another batch of the same size, with corks treated with the material and the conditions of the pack. invention (tests E1 to E7).

Both types of corks were introduced into Bordeaux bottle necks. They were placed for 40 days in an enclosure containing oxygen.

The analyzes were made with a dry gas (argon) and at room temperature.

The following results of oxygen permeability were observed:

Test E0 (cork lot cork natural commercial): 0.00030 to 0.1277 cm ³ / 24H / Bottle.

Test E1 to E7 (cork lot natural cork treated according to the invention): 0.00005 to 0.0050 cm ³ / 24H / Bottle.

In view of these results, it appears:

on the one hand, that the control plugs have a very large dispersion of the results (from 3.10 ^-4 to 0.12 cm ³ ₂ / day, which is considerable compared with the range 5.10 ^-5 × 5.10 ^-3 cm ³ 0 ₂ / day, for plugs according to the invention, which corresponds to a relatively low dispersion of values. - and secondly that the values of permeability have dropped sharply and that they have been divided by at least 10.

6 - Liquid tightness test

Lot of ten bottles filled with wine and filled with corks of natural cork length 45 mm and diameters 24 mm (tests E0 to E7) were placed in an oven initially at 30 ° with temperature rise in increments of 5 ° C up to 60 ° C, the bottles being kept at the temperature of each stage for 4 days. At the end of this test, a visual examination and a weighing can detect a possible leak: a bottle is considered to have leakage if a weight loss of at least 2 g is observed.

Results: the control plugs of the E0 test exhibited a leakage rate of 5%, whereas the plugs of all the tests E1 to E7 according to the invention had a leakage rate of 0%.

7 - Measuring the Barrier Effect on Harmful Molecules 7-1 Procedure:

a- selection of 15 natural corks,

b) Maceration of the stoppers in a 15% by volume aqueous ethanol solution of ethanol, acidified to a pH of 3.5 for three days at ambient temperature. Search and determination of releasable haloanisoles

The haloanisole contents released in the hydroalcoholic solution were determined by SPME (Solid Phase Micro Extraction) and SBSE (Stir Bar Sorptive Extraction):

7-2 Demonstration of the barrier effect of the treatment according to the invention

Different batches of L1 to L5 plugs have been variously contaminated with haloanisoles. On each of these batches, a first sampling of 15 caps was used to determine the haloanisole content "before treatment", and on a second sample of 15 caps performed the treatment of the E7 test; then the haloanisole content "after treatment" was determined. The following table indicates the contents found expressed in ng / l (nanogram per liter): Before treatment After treatment Efficiency in%

L1 85.9 15.7 82

L2 38.1 7.0 82

L3 22.7 1, 9 92

L4 19.3 1, 5 92

L5 8.2 0.7 91

It can be seen from this table that the treatment according to the invention can be effectively applied to relatively polluted plugs with a haloanisole content of approximately 23 ng / l, given that the detection threshold is 2 ng / l.

Moreover, when it is known that the usual haloanisole contents of the so-called natural plugs or plugged commercial plugs are around 10 ng / I, it is clear that the invention can ensure for corks a haloanisole content lower than detection threshold of 2 ng / l. 8 - Sensory analysis tests

The Applicant has also carried out tests of sensory and taste analysis of water, in which plugs had been immersed beforehand for at least 24 hours, each in a glass of water deemed organoleptically neutral. It appeared that after a significant number of tests representative: - at least 80% of commercial natural cork stoppers (test E0), have produced odors and tastes of corks making water hard to drink.

- 100% of the corks treated with the material and according to the treatment of the invention (tests E1 to E7) did not induce any detectable organoleptic deviation olfactory or tasting water.

F) General conclusions

All the checks and tests carried out comparatively, and grouped under the preceding 8 items, have shown that the corks obtained by the treatment according to the invention have properties always superior to those of the control corks.

The invention makes it possible to economically produce a large variety of corks with properties and performances adapted to the particular requirements of each type of wine to be bottled, in particular by adding to said liquid composition of all kinds of additives, such as Ti0 ₂ , Si0 ₂ , SiOx, talc, clays, kaolin, barium sulfate.

LIST OF REFERENCES

Cork stopper 100

Bottle 101

Overcap Capsule 102

Liquid in the bottle 103

Cell structure of cork 200

Anfractuosity of cork 201

"L + P" composite skin 204

½ cap left cut 300a

½ 300b cap straight cut

301 composite skin

Skin or inner lining (with tracer) .... 304

Bottle portion 600

Collar of the bottle 601

Waterproof envelope 610

Waterproof metal plate 611

Cord of waterproof material 612

613 gas inlet tube

614 gas outlet tube

800 Wiper Reactor

Spherical wiper reactor 800a

800b cylindrical wiper reactor

800c Frustoconical Wringer Reactor

Outside wall 801

Central basket with perforated wall 802

Central tree 803

Central and perforated hollow shaft 803 '

Air inlet under pressure 804

Vacuum outlet for pressure P ₂ 805

Upper hatch of 801 806

Lower hatch of 801 807

Trap of 802 808

Evacuation of hot air 809 Supply & drain hose 810

Corks to be processed - batch of 900 caps

Natural cork stoppers 900a

Clogged corks 900b Clog retention net 901

Tank or pressure vessel 902

Fluid liquid composition 903

904 tank cover

Measurement of applied pressure 905 Vacuum tank 902 '

Liquid composition 903 '

Tank cover 904 '

Applied vacuum measurement 905 '

Desorbed liquid composition 906 Wringer 910

Access port 911

912 polymer extraction pump

Vertical oven-duct 920

Caps to dry and cure 921 Turbine 922

Heating resistors 923

924 bottom grid

Top grid 925

Shutter 926 Horizontal Evacuation Line 927

Ready-to-use treated cap 928

Packing net 929

Claims

1. Treatment of natural cork stoppers (900) successively comprising the following steps a, c and d:

a) supplying a batch of a plurality of so-called natural plugs (900a) and impregnating said batch in a liquid composition CP (903) comprising at least one polymeric material P, at a pressure Ρ _Ί greater than the atmospheric pressure P _A , so as to obtain a so-called impregnated batch,

so as to obtain a batch of so-called treated plugs (928), each plug (928) having a "composite skin" (204, 301, 304) of cork L impregnated with polymeric material P, represented symbolically by "L + P".

2. Treatment of natural cork stoppers (900) according to claim 1 further comprising a step b) vacuum treatment, inserted between said steps a) and c) so as to have successively the following steps a) to d) :

a) supplying a batch of a plurality of so-called natural plugs (900a) and impregnating said batch in a liquid composition CP (903) comprising at least one polymeric material P, at a pressure Pi greater than atmospheric pressure P _A , so as to obtain a so-called impregnated batch,

c) then, said batch treated under vacuum is drained, so as to obtain a said batch wrung, d) finally, said wrung batch is subjected to a heat treatment.

3. Treatment according to any one of claims 1 to 2 wherein, in step a), said batch of plugs (900a) is immersed in a first container (902) resistant to pressure containing said liquid composition (903), and said container (902) is pressurized with an air pressure of between 2 and 6 bar and preferably 3 to 5 bar, said air pressure Ρτ being applied inside said first container (902) on a duration between 1 and 15 minutes and preferably from 3 to 10 minutes.

4. Treatment according to any one of claims 2 to 3 wherein, in step b) of the treatment, said impregnated batch is treated under vacuum, inside a container capable of keeping to a vacuum (902 '), with a pressure P ₂ ranging from 0.1 to 4 mbar, and preferably ranging from 0.5 to 1.5 millibar.

5. Treatment according to any one of claims 1 to 4 wherein, in step c) of the treatment, after venting, the batch of corks treated under vacuum, once introduced into a wringer (910), is drained by cycles, each cycle comprising a spin phase lasting from 0.5 to 5 minutes, preferably between 1 and 3 minutes, with a number of cycles of between 1 and 5 and preferably of between 2 and 3, and a riddling phase of the plugs being interposed between each spin phase, lasting between 3 seconds and 1 minute and preferably between 5 seconds and 30 seconds, and during which the plugs change position and space inside the drum of the wringer (910).

6. Treatment according to any one of claims 1 to 5 wherein, in step d) of the treatment, after extracting the batch of plugs (921) of the wringer (910) in step c) of the treatment, said batch of plugs (921) is treated, in a chamber (920), with a flow of hot air at a speed of between 3.0 and 20.0 meters per second and preferably between 5.0 and 10.0 meters by seconds, so as to form said heat treatment, said heat treatment being intended in particular to remove a solvent from said liquid composition CP, when said liquid composition CP comprises a solvent.

7. Treatment according to any one of claims 1, 2, 3, 4 and 6 wherein in step a) of the treatment, a batch of so-called plugged plugs (900b) is supplied, and step b) is eliminated. under vacuum.

8 Treatment according to any one of claims 1 to 7 wherein said liquid composition CP (903) comprises, in addition to said polymeric material P, at least one additive A intended to promote the sliding of the plug in contact with the glass, so that said plug treated has a "skin" of composition symbolically represented by "L + P + A".

9. Treatment according to any one of claims 1 to 8 wherein said liquid composition CP (903) forms an emulsion or a dispersion in phase aqueous solution of at least one polymeric material P being among the polymeric materials:

a) approved for food contact,

b) capable of forming a barrier to said harmful molecules,

said polymeric material P being preferably an acrylic polymer emulsion in an aqueous medium or an aqueous composition based on EVOH, a copolymer of ethylene and of vinyl alcohol.

The treatment of any one of claims 1 to 9 comprising:

a) a said first succession of at least steps a), c) and d), from a said first polymer liquid composition CP ^ typically formed by the said liquid composition CP comprising the said polymeric material P, so as to form a said first impregnation,

b) and a complementary treatment comprising, for example, a said second succession of at least steps a), c) and d), from a said second polymeric liquid composition CP ₂ , at least the said second liquid polymer composition CP ₂ comprising said additive A for promoting the sliding of said plugs, so as to form a said second impregnation, so that said treated plug has a composite "skin" of composition symbolically represented by. "L + P / A".

1 1. Treatment according to any one of claims 1 to 10 wherein said liquid composition CP (903), CP or CP ₂ comprises an elastomeric material E selected from: butyl rubber, nitrile rubber, thermoplastic elastomers such as SIS (styrene isoprene styrene) ), SBS (styrene butadiene styrene), SEBS (styrene ethylene butylene styrene), MS Polymer (odified Silicon Polymer) or PDMS (Polydimethylsiloxane).

12. Treatment according to any one of claims 8 to 1 1 wherein said additive A for promoting the sliding of the plug in contact with the glass is an anionic emulsion wax, typically based on paraffin wax or carnauba wax, or a silicone resin when said first polymeric liquid composition CPi comprises said aqueous EVOH-based composition, so as to cover said EVOH-based polymeric material P with a layer forming both a water barrier and an agent slip, said additive A being able to be a additive A ₂ constituent of said second polymeric liquid composition CP ₂ , said second polymeric liquid composition then being free of EVOH.

13. Treatment according to any one of claims 1 to 12 wherein said liquid composition CP (903) comprises a micronized mineral filler B forming a barrier, in particular to the diffusion of gases, said inorganic filler being selected from: silica Si0 ₂ , a silicon oxide SiO _x (with x <2), titanium oxide TiO ₂ , micronized clay, kaolin, barium sulfate.

14. Cork cork obtained by the treatment according to any one of claims 1 to 13 characterized in that it has on all of its accessible surface, outer surface and inner surface cavities or crevices said plugs, a surface area of cork L comprising penetration of said polymeric material P in its mass with incorporation of said polymeric material P to the cork, so that said treated plug has a composite skin (204, 301, 304) of composition symbolically represented by "L + P Said composite skin (204, 301, 304) having a thickness E of at least 10 μm and up to 1 mm, depending on the local hardness or porosity of the natural cork or its constituents.

The cork stopper of claim 14 wherein said cork surface area L forming said composite skin (204, 301, 304) comprises, in addition to incorporating said polymeric material P into the cork, incorporating said additive A for promote the sliding of the plug in contact with the glass, so that said treated plug has a composite skin of composition symbolically represented by "L + P + A" or "L + P / A" according to whether said additive A is incorporated in said polymeric material P or covers said polymeric material P.

The cork stopper according to any of claims 14 to 15 wherein said cork surface area L forming said composite skin (204, 301, 304) comprises, in addition to incorporating said polymeric material P into the cork and incorporating said additive A, the incorporation of at least one adjuvant chosen from: a micronized mineral filler B forming a barrier, in particular to the diffusion of gases, an elastomeric resin E.