Method for decontaminating preforms by means of reactive species obtained by mixing precursor reagents and plasma

Abstract

The invention relates to a method for decontaminating a preform (14) made of a thermoplastic material by exposing at least a portion of the preform (14) to a reactive substance (RS) obtained by mixing a precursor reagent (AP) with a plasma (P) generated by injecting a carrier gas (G) in a reactor (40), characterized in that the mixing between the precursor reagent (AP) and the plasma (P) takes place only outside the reactor (40) before contacting the preform (14). The invention also relates to a decontaminating device (50) for carrying out the method.

Description

[0001] This application is a divisional application based on the Chinese patent application with the application date of July 9, 2020, application number 202080050076.9, and invention name “Preform decontamination method with the aid of reactive substances obtained by mixing precursor reagents and plasma”. Technical Field

[0002] The invention relates to a method for decontaminating a preform made of thermoplastic material by exposing at least a portion of the preform to a reactive species obtained by mixing a precursor reagent with a plasma generated by injecting a carrier gas into a reactor. Background Art

[0003] In the field of produce packaging, it is known to carry out decontamination treatments to sterilize or disinfect at least certain parts of a container intended to contain food products, in particular the interior and the neck of the container.

[0004] The purpose of the decontamination treatment applied is to destroy or at least reduce the presence of microbiological organisms or microorganisms, such as in particular germs, bacteria, spores, molds, etc., in order to enable the food to be preserved.

[0005] A container is a hollow body such as a bottle, flask, jar, etc., obtained by transforming a preform made of thermoplastic material, which has been previously manufactured, usually by injection molding. The preform comprises in particular the body intended to be formed into its final shape during the manufacturing process, and also the neck which already has its final shape.

[0006] Among thermoplastic materials, PET (polyethylene terephthalate) is most commonly used for these applications.

[0007] During the container manufacturing process, the body of the preform is first thermally conditioned in an oven to soften the constituent materials. To this end, the oven includes heating means, in particular heating means that emit heating electromagnetic radiation, such as by infrared lamps. The thus softened preform is then transformed into a container by blowing it into a mold (with or without stretching) using at least one pressurized fluid. The neck of the preform is kept at a sufficiently cool temperature so that it does not deform during the container manufacturing process.

[0008] As a variant, the injected preform is converted directly into a container without prior thermal conditioning.

[0009] In the prior art, preforms are decontaminated, in particular, by a "chemical route" using disinfectants containing hydrogen peroxide (H2O2) or other products with similar properties (i.e., bactericides, virucides, fungicides, etc.). This more particularly involves so-called "precursor" agents that can decompose into reactive species, in particular reactive oxygen species, known by the acronym "ROS" for "Reactive Oxygen Species." Reactive oxygen species include, in particular, hydroxyl radicals, superoxide anions, hydroxyl ions, etc. Bacteria and viruses are very effectively destroyed by contact with reactive oxygen species.

[0010] The decomposition of the precursor reagent into reactive oxygen species is performed, for example, by heating the precursor reagent at an elevated temperature for at least a determined minimum duration.

[0011] Disinfection with reactive oxygen species is highly effective and is particularly harmless to the user, as the final residues of the chemical reaction consist only of water and oxygen.

[0012] Thus, it is known to inject a precursor agent (e.g., a solution of hydrogen peroxide and water) into a preform in a vaporous state before the preform passes through a furnace. This vapor condenses upon contact with the inner wall of the preform. As the preform passes through the furnace, the condensed precursor agent is then heated simultaneously with the bulk of the preform by the furnace's heating elements. This heat is generally sufficient to partially decompose the precursor agent contained in the preform.

[0013] Thus, throughout the entire manufacturing process of the container, until the container is filled, the preform contains a sterile atmosphere.

[0014] However, the heat received by the precursor reagents contained in the preform during its heating is generally insufficient to decompose all of the precursor reagents into reactive oxygen species. The amount of heat transferred to the preform depends on, for example, the size of the preform, the shape of the final container, the color of the preform, etc.

[0015] To address this problem, the preform may be heated in the furnace longer than necessary to allow most of the precursor reagents to decompose into reactive oxygen species.

[0016] However, it is not always possible to heat the precursor reagents sufficiently without degrading the preform.

[0017] Furthermore, the requirement to continue heating the preform once the body of the preform has reached the temperature required to be formed into the final container results in increased costs to manufacture the container.

[0018] Furthermore, even if the reaction residues of the reactive oxygen species are harmless, the precursor reagents (particularly hydrogen peroxide) can be toxic above a certain dose. This is particularly problematic when the container is intended to contain food. For this reason, some countries have set strict standards for the amount of precursor reagent residues allowed in filled containers. For example, a container should contain less than 0.5 ppm of precursor reagent.

[0019] To achieve this goal, and in view of the heating problem mentioned above, it is sometimes necessary to dilute the precursor reagent in a harmless solvent (such as water) to reduce the amount of precursor reagent injected into the container.

[0020] However, by reducing the level of precursor reagent, the efficiency of the sterilization process is significantly reduced.

[0021] It has been proposed to decompose precursor reagents with the aid of plasma. To this end, it is known to inject the precursor reagent mixed with a carrier gas (such as air) into a capacitive plasma reactor. This reactor comprises a reaction chamber containing two electrodes, between which a strong potential difference is applied. This leads to ionization of the carrier gas, which activates the decomposition of the precursor reagent into reactive oxygen species. This solution advantageously makes it possible to decompose almost all of the precursor reagent into reactive oxygen species even before contact with the object to be decontaminated.

[0022] It is known that the carrier gas at least partially decomposes into reactive species. However, due to the presence of the precursor reagents, the concentration of reactive species becomes extremely high. The reaction chamber then exhibits a high concentration of reactive oxygen species. These components (especially hydroxyl ions) have very strong oxidizing power and are therefore particularly corrosive. As a result, the electrodes, regardless of their material, wear out quickly and must be replaced very frequently. Summary of the Invention

[0023] The present invention provides a method for decontaminating a preform made of thermoplastic material by exposing at least a portion of the preform to a reactive species obtained by mixing a precursor reagent with a plasma generated by injecting a carrier gas in a reactor.

[0024] The method of the invention is characterized in that the mixing between the precursor reagents and the plasma takes place only outside the reactor before contact with the preform.

[0025] Thus, the electrodes of the reactor are never in contact with the precursor reagents or reactive species obtained by decomposition of the precursor reagents in contact with the plasma.

[0026] Other characteristics of the method according to the invention:

[0027] at least one inner surface (28) of the preform is exposed to a reactive substance, said reactive substance being confined inside the preform for a duration determined by confinement means;

[0028] - the method is carried out while the preforms are being conveyed through an installation for manufacturing containers from preforms, the installation comprising an oven for heating the preforms, the reactive substance being injected into the preforms before or during heating of the preforms in the oven, the reactive substance being confined in the preforms until they leave the oven;

[0029] - The reactive substance is confined in the preform by a confinement device fixed to the inside of the neck of the preform.

[0030] - The reactive substance is confined in the preform by a confinement device fixed to the outside of the neck of the preform.

[0031] Such a restriction device, fixed to the inside or outside of the neck, makes it possible to isolate the interior of the preform from its external environment.

[0032] The reactive mass is confined in the preform by means of a mandrin which grips the preform by its neck to enable its movement in the furnace;

[0033] - Precursor reagents are mixed with the plasma at the outlet of the reactor;

[0034] - the precursor reagent comprises hydrogen peroxide;

[0035] - the precursor reagent is in a vapor state when it is mixed with the plasma;

[0036] - the precursor reagent is in the form of a mist when it is mixed with the plasma;

[0037] - the carrier gas is formed from molecular oxygen;

[0038] -The carrier gas is air;

[0039] - The reactive substance contains one or more of the following chemical components:

[0040] --Reactive oxygen species (ROS);

[0041] --Reactive nitrogen species (RNS);

[0042] --Ozone (O3).

[0043] The invention also relates to a decontamination device for carrying out the decontamination method according to the teachings of the invention.

[0044] The decontamination device is characterized in that it comprises:

[0045] a decontamination conduit connected at its upstream end to a source of precursor reagent and at its downstream end to at least one injection nozzle intended to inject a reactive substance onto at least a portion of the preform, this reactive substance being obtained by decomposition of the precursor reagent when it is mixed with the plasma;

[0046] - a plasma reactor connected to a carrier gas source and having its outlet connected to a decontamination line via an embranchment that divides the decontamination line into an upstream section and a downstream pipe section, in which the undecomposed precursor reagent is intended to circulate, and in which the reactive oxygen species produced by the decomposition of the precursor reagent when it is mixed with the plasma are intended to circulate.

[0047] Other characteristics of the decontamination device according to the invention:

[0048] - the plasma reactor is a cold plasma reactor, such as a corona discharge reactor or a dielectric barrier discharge reactor;

[0049] - the decontamination line comprises a precursor reagent vaporizer arranged upstream of the branch with the plasma reactor;

[0050] The decontamination conduit comprises precursor reagent atomizing means arranged upstream of the branch. BRIEF DESCRIPTION OF THE DRAWINGS

[0051] Other features and advantages of the present invention will become apparent after reading the following detailed description. For an understanding of the detailed description, please refer to the accompanying drawings, in which:

[0052] [ Figure 1 ] Figure 1 is a schematic top view showing an example of an apparatus for manufacturing containers by shaping preforms, equipped with a decontamination device implemented according to the teachings of the present invention;

[0053] [ Figure 2 ] Figure 2 is a side view showing an example of a preform that can be decontaminated by applying the method according to the teachings of the present invention;

[0054] [ Figure 3 ] Figure 3 is a schematic diagram showing a decontamination apparatus designed to implement the decontamination method according to the teachings of the present invention;

[0055] [ Figure 4 ] Figure 4 is a block diagram illustrating a decontamination method implemented according to the teachings of the present invention;

[0056] [ Figure 5 ] Figure 5 is an axial cross-sectional view schematically showing a portion of a conveyor chain including a tournette for conveying preforms through a heating furnace;

[0057] [ Figure 6 ] Figure 6 is a side view schematically illustrating a preform exposed to a laminar air flow capable of confining reactive species contained within the preform. DETAILED DESCRIPTION Detailed Description of the Invention

[0059] In the rest of the specification, elements having the same structure or similar function will be denoted by the same reference numerals.

[0060] Figure 1 1 shows a plant 10 for manufacturing containers in large quantities. Such a plant 10 enables the production of a final container 12 by shaping a preform 14.

[0061] Figure 2 An example of a preform 14 made of thermoplastic material is shown. Here, the preform 14 is made of polyethylene terephthalate (PET).

[0062] Such a preform 14 is generally obtained by injecting plastic material and has characteristics (dimensions, material distribution, etc.) determined by the final container 12 to be obtained (in particular its shape or its capacity).

[0063] The preform 14 has Figure 2 The preform 14 notably comprises a tubular body 16 closed at the lower end by a bottom 18 and open upwards by an upper opening 20 radially delimited by a neck 22 .

[0064] The major axis “A” of the preform 14 passes through the center of the neck 22 .

[0065] The neck 22 of the preform 14 has its defined shape at the end of its manufacture by injection molding and corresponds to the neck of the final container 12. An edge 24 of the free upper end of the neck 22, also called the buvant, circumferentially delimits a circular opening 20 which constitutes the only access to the interior of the preform 14.

[0066] exist Figure 2 In the example shown, the neck 22 includes a flange 26 extending radially outwardly. The body 16 is defined by a tubular wall having a shape located inside the preform 14 and extending radially outwardly. Figure 2The inner surface 28 and the outer surface 30 located on the outside are shown in dashed lines.

[0067] The preform 14 has, for example, an opening 20 with an inner diameter of approximately 20 mm and an overall height of approximately 90 mm. The thickness of the wall defining the body 16 is, for example, approximately 3 mm. These values ​​are given by way of non-limiting example, and the preform 14 can have different dimensions while maintaining approximately the same proportions.

[0068] Reference again Figure 1 The manufacturing apparatus 10 generally comprises a heating furnace 32 including means 33 for heating the body 16 of the preform 14 above the glass transition temperature at which the material becomes ductile. To ensure that the neck 22 of the preform 14 does not deform during the manufacturing process, the furnace 32 includes means for maintaining the temperature of the neck 22 below its glass transition temperature.

[0069] The heating oven 32 comprises means 35 for in-line conveying of the preforms 14. The conveying means 35 comprise individual supports that circulate in a closed circuit in the heating station 10.

[0070] exist Figures 2 to 4 In the embodiment shown, the conveying device 35 comprises a plurality of conveying elements 37 forming links of a closed conveyor chain. Each conveying element 37 carries at least one individual support. Each individual support comprises a clamp 39. The clamp 39 is intended to engage in the neck of the preform 14. According to a known embodiment, the clamp 39 is provided with elastic means (not shown), such as an O-ring, advantageously made of an elastic material (e.g. an elastomer) and having an outer diameter equal to or slightly greater than the inner diameter of the neck of the preform 14, in order to ensure that the preform 14 is supported by friction against the inner wall of the neck when the clamp 39 engages, and that the interior of the preform is isolated from its external environment, thereby ensuring the quality of decontamination.

[0071] Typically, each chuck 39 comprises a device such as a small gear 41 cooperating with a fixed belt (not shown) capable of driving the preform 14 in rotation about its main axis during at least a portion of its movement along the conveying path so as to enable the body of the preform 14 to be heated uniformly. Such a conveying device 39 with a rotating chuck is sometimes referred to as a "rotator". The manufacturing plant 10 also comprises a blowing station 34 comprising a molding unit 36 ​​capable of receiving the preform 14. The preform 14 is intended to be formed into a final container 12, for example, by stretch-blowing in a mold (not shown) of the molding unit 36. The molding unit 36 ​​is mounted on a turntable 38 that enables the preform 14 to move during its transformation into the final container 12 from an entry point to an exit point.

[0072] During the manufacturing process, the preforms 14 and then the containers 12 are moved online by conveyors along a defined production path, such as Figure 1 The conveyor comprises individual support means (not shown) for each hollow body in the state of a preform 14 or container 12. These conveyors are well known in the art and will not be described in detail here.

[0073] The manufacture of the containers 12 is not carried out in a sterile room, even when they are intended for food use. It is therefore necessary to provide a decontamination device for the preforms 14.

[0074] The present invention provides a method for decontaminating a preform 14 made of thermoplastic material by exposing at least a portion of the preform 14 to a reactive species "RS" obtained by mixing a precursor agent "AP" with a plasma "P." This more particularly relates to a reactive species having sterilizing properties. The decontamination method is advantageously carried out during the loading of the preform into a container manufacturing facility, more particularly during the conveyance of the preform through the facility.

[0075] The reactive substance consists in particular of one or more of the following chemical components:

[0076] - Reactive oxygen species, also known by its English acronym "ROS", which stands for "Reactive Oxygen Species", include hydroxyl radicals, superoxide anions, hydroxyl ions, perhydroxyl radicals, etc.;

[0077] - reactive nitrogen species, also known by their English acronym “RNS”, which stands for “Reactive Nitrogen Species”, which include in particular nitric oxide (NO);

[0078] -ozone.

[0079] Such a precursor agent "AP" is defined as an agent capable of decomposing into reactive species "RS" by exposure to a plasma "P." Advantageously, the precursor agent "AP" is selected to completely decompose into reactive species "RS," thereby eliminating the need to clean the container 12 at the end of its manufacturing process.

[0080] This precursor reagent "AP" is formed, for example, from hydrogen peroxide (H2O2), in particular from a solution of hydrogen peroxide and water.

[0081] The concentration of hydrogen peroxide in the aqueous solution is, for example, 5% to 35%. Hydrogen peroxide and / or water can easily decompose into a number of reactive oxygen species (ROS).

[0082] Furthermore, the reactive species "RS" obtained by exposing hydrogen peroxide to the gas in the plasma "P" state is stable for a long enough time to allow the preform 14 to be decontaminated throughout its manufacturing process. The reaction between different reactive species "RS" actually promotes the generation of new reactive species "RS".

[0083] Plasma "P" is generated by injecting a carrier gas into reactor 40. The carrier gas is typically molecular oxygen (O2), in which case the reactive species "RS" generated by mixing plasma "P" with precursor reagents "AP" are primarily reactive oxygen species.

[0084] As a variant, the carrier gas can also be formed from another pure gas or even from a composition (such as air). When the carrier gas is formed from a nitrogen-containing gas such as air, the plasma contains reactive nitrogen species and reactive oxygen species. These reactive species react with the precursor reagent "AP" upon mixing to form new reactive oxygen species. Thus, the reactive species produced by the mixture contains a mixture of reactive oxygen species and reactive nitrogen species.

[0085] Reactor 40 can generate a cold plasma "P" at atmospheric pressure. Plasma "P" is obtained, for example, by supplying electromagnetic energy to a carrier gas "G." To this end, reactor 40 is, for example, a capacitive reactor 40, which primarily includes a reaction chamber 42. Two electrodes 44 are located in this reaction chamber 42 and are electrically connected to a DC or AC current generator 46, thereby allowing a strong potential difference to be applied between the two electrodes 44.

[0086] According to a first embodiment, not shown, this involves a corona effect reactor, in which an arc can be generated between two electrodes if a potential difference greater than the breakdown voltage is applied between the two electrodes.

[0087] according to Figure 3 The second embodiment shown is a dielectric barrier discharge reactor 40, or "DBD" according to the English acronym. In this reactor 40, a baffle 48 made of a dielectric material is inserted between two electrodes 44. This makes it possible, in particular, to avoid arcing between the two electrodes 44.

[0088] It has been observed that contact of the electrode 44 with the precursor reagent "AP" tends to prematurely wear out the electrode 44 due to oxidation.

[0089] In order to solve this problem while maintaining the advantages of generating reactive species "RS" by plasma "P", the present invention proposes that the mixing between the precursor reagent "AP" and the plasma "P" is carried out only outside the reaction chamber 42 of the reactor 40 before contact with the preform 14. As a result, neither the precursor reagent "AP" nor the reactive species "RS" obtained by the contact between the precursor reagent "AP" and the plasma "P" comes into contact with the electrode 44. This thus avoids premature corrosion of the electrode 44. Moreover, the fact that the mixing is achieved before contact with the preform 14 makes it possible to decompose substantially all of the precursor reagent "AP". As a result, the residual content of the precursor reagent "AP" in the container 12 made from the preform 14 thus treated is advantageously negligible.

[0090] The precursor reagent "AP" is advantageously mixed directly with the plasma "P" at the outlet of the reactor 40. Therefore, most of the carrier gas "G" is still in the plasma "P" state when mixed with the precursor reagent "AP".

[0091] To facilitate the generation of reactive species "RS," the precursor agent "AP" is vaporized before it is mixed with the plasma "P." Thus, the precursor agent "AP" is in a vapor state when it is mixed with the plasma "P."

[0092] As a variant, the precursor agent "AP" is mixed with the plasma "P" in the form of a mist.

[0093] like Figure 4 As shown, the method of the invention thus comprises a first step “E1” of generating a plasma “P” by means of the reactor 40, followed by a second step “E2” of mixing a precursor reagent “AP” with the plasma “P” outside the reactor 40, followed by a third step “E3” of spraying the reactive species “RS” obtained during the second step “E2” onto the portion of the preform 14 to be decontaminated.

[0094] Both the interior surface 28 and the exterior surface 30 of the preform 14 may be decontaminated by this method.

[0095] However, this method is particularly advantageous for decontaminating the interior surface 28 of the preform 14 that is difficult to access and the neck 22 that is not heated by the furnace 32 .

[0096] In the case of decontamination of the interior of the preform 14 , the method advantageously, but not necessarily, comprises a step “ E4 ” of confining the reactive substances “RS” inside the preform 14 for a duration determined from the start of their injection, for example less than 12 seconds.

[0097] When the reactive substance “RS” is injected into the preform 14 upstream of the heating oven 32 , the determined duration corresponds to the time it takes for the preform 14 to exit the heating oven 32 , for example less than 12 seconds.

[0098] In this case, the confinement of the reactive species “RS” is achieved by means of a clamp 39 which blocks the preform 14 during its passage through the furnace 32 .

[0099] This confinement ensures that the reactive species are located where they are intended to be contaminated and prevents them from escaping into the interior of the furnace. Diffusion of these reactive species can lead to oxidation of metal parts in the furnace.

[0100] Furthermore, this confinement makes it possible to ensure that the reactive substance remains in contact for a certain period of time with the volume defined by the inner wall of the preform, thus guaranteeing the efficiency of the decontamination step.

[0101] When the reactive substance "RS" is injected into the preform 14 at another location in the apparatus (e.g., downstream of the heating furnace 32), the confinement can be achieved by physically blocking the preform 14 with a plug or by injecting a laminar air stream "F" directly toward the interior of the preform 14 at right angles to the neck parallel to the axis of the preform 14. The air stream "F" should then have a size that is greater in cross section than the size of the neck of the preform 14 to avoid that the air stream drives out the reactive substances instead of confining them, as Figure 6 Indicated by the bundle of parallel arrows "F".

[0102] Figure 3 An example of a decontamination apparatus 50 is shown, which is used to implement a decontamination method according to the teachings of the present invention.

[0103] The decontamination device 50 comprises a decontamination conduit 52, the upstream end 54 of which is connected to a source 56 of a precursor agent "AP" and the downstream end 58 of which is connected to an injection nozzle 60 intended to inject a reactive substance "RS" onto or into the preform 14. In the example shown, this is a nozzle 60 intended to inject the reactive substance "RS" into the interior of the preform 14. The source 56 of the precursor agent "AP" delivers the precursor agent "AP" under pressure to allow it to flow towards the nozzle 60.

[0104] The decontamination device 50 also includes a reactor 40 for the plasma "P". The reactor 40 includes a reaction chamber 42, at least one inlet orifice 62 of which is connected to a source 64 of a carrier gas "G" and an outlet 66 of which is connected via a branch 68 to an intermediate section of the decontamination conduit 52. The branch 68 divides the decontamination conduit 52 into an upstream section 52A, in which the undecomposed precursor reagent "AP" is intended to circulate, and a downstream section 52B, in which the reactive species "RS" generated by the decomposition of the precursor reagent "AP" when it is mixed with the plasma "P" are intended to circulate.

[0105] The carrier gas "G" delivered by source 64 is, for example, molecular oxygen or air.

[0106] Carrier gas “G” may be injected under pressure to allow it to flow toward outlet 68 .

[0107] A check valve 70 may be provided at the outlet of the reaction chamber 42 to prevent the precursor reagent “AP” or the reactive species “RS” obtained by decomposition of the precursor reagent “AP” from accidentally returning to the reaction chamber 42 .

[0108] As a variant, when the plasma (P) is generated by injecting a carrier gas into the reactor, the pressure in the reactor is greater than the pressure in the decontamination line (52). Thus, during the implementation of this decontamination method, the pressure in the reactor is greater than the pressure in the decontamination line (52), which avoids any rise of the precursor reagent (AP) and / or the reactive species in the reactor and thus makes it possible to avoid any oxidation of the reactor. For this purpose, the plasma is advantageously generated before and after the step of evaporation of the precursor reagent in the decontamination line (52).

[0109] The reaction chamber 42 includes two electrodes 44 spaced apart from each other. The electrodes 44 are connected to a current generator 46. The electrodes 44 are arranged so that the carrier gas "G" circulating from the inlet orifice 62 to the outlet orifice 66 passes through the space formed between the two electrodes 44. The potential difference applied between the electrodes 44 is sufficient to convert the carrier gas "G" into a plasma "P".

[0110] This is a dielectric barrier 48 discharge reactor 40 . A barrier 48 of dielectric material is inserted between two electrodes 44 .

[0111] When the precursor reagent "AP" is delivered in liquid form by the source 56 of the precursor reagent "AP", the decontamination line comprises an evaporator 72 of the precursor reagent "AP" arranged upstream of the branch of the reactor 40 with the plasma "P". The precursor reagent "AP" is heated, for example, by resistance.

[0112] As a variant, this involves a heat exchanger.

[0113] According to another variant of the invention, the vaporizer is replaced by atomizing means of the precursor reagent "AP" arranged upstream of the branch.

[0114] exist Figure 1 In the example shown, the decontamination device 50 is arranged to treat the preforms 14 upstream of the furnace 32. The heat provided by the furnace can indeed accelerate the reaction between the reactive substance "RS" and the microbiological agents present on the surface of the preforms 14. However, the decontamination device 50 can also be arranged at other locations in the manufacturing facility 10, for example downstream of the furnace 32.

[0115] It has been discovered that decontamination of the interior of the preform 14 is even more effective when the reactive species “RS” is confined to the interior of the preform 14 after being injected into the preform 14 .

[0116] When the decontamination device 50 is used, the reactor 40 is supplied with a carrier gas “G” to generate a plasma “P” of this carrier gas “G.” The plasma “P” thus obtained is injected into the decontamination duct 52 at the branch 68 .

[0117] At the same time, the precursor reagent "AP" evaporated by the vaporizer 72 is supplied to the pipe 52. The precursor reagent "AP" thus evaporated is then mixed with the plasma "P" at this branch without entering the reactor 40. This mixing activates the decomposition of the precursor reagent "AP" into the reactive species "RS". The reactive species "RS" thus obtained is then sprayed onto the surface to be decontaminated of the preform 14, here, the interior of the preform 14, so as to decontaminate the inner surface 28 thereof.

[0118] In practicing this method, all precursor reagents introduced into the decontamination line 52 may be fully activated by the plasma.

[0119] In a particular embodiment, it is possible that only a portion of the precursor reagent introduced into the decontamination conduit 52 is activated by the plasma. In this embodiment, the precursor reagent is activated in two complementary ways. There is a first amount of precursor reagent that is directly activated by the plasma, and a precursor reagent amount that is not directly activated is injected into the preform. The precursor reagent amount that is not directly activated is injected into the preform in vapor form, then condenses on the inner wall of the preform body and is activated by a heating element (i.e., an IR lamp or a laser diode).

[0120] When the precursor reagent reaches a certain temperature, decontamination of the preform by the thermally activated precursor reagent, in particular hydrogen peroxide, begins.

[0121] In this embodiment, the decontamination method comprises two precursor reagent activation phases, wherein the plasma activation phase allows for almost immediate activation of the precursor reagent, that is, the decontamination of the preform begins as soon as the mixture activated by the plasma comes into contact with the preform (in particular, the body of the preform). The method comprises a second activation phase for activating the previously inactivated amount of precursor reagent.

[0122] Therefore, the kinetics of the two activation phases are different. The reaction kinetics of the first activation phase is faster than the reaction kinetics of the second activation phase.

[0123] Advantageously, depending on the amount of precursor reagent injected, it is possible to combine the proportions of the two precursor reagent activation phases. This makes it possible to increase the overall kinetics of preform decontamination and therefore also its decontamination rate.

[0124] Furthermore, the fact of having two activation stages makes it possible to control the amount of residual precursor reagent remaining in the preform at the furnace outlet, ie at the end of decontamination.

[0125] The method according to the invention and the device 50 for its implementation make it possible to very advantageously decontaminate the preform 14 from the precursor agent "AP" (for example hydrogen peroxide), while obtaining a final container having negligible residual amounts of the precursor agent "AP". It is therefore not necessary to wash the container 12 at the end of its manufacturing process.

[0126] Furthermore, the fact of mixing the plasma "P" with the precursor reagent "AP" makes it possible to obtain results as satisfactory as by mixing it inside the reactor, but without causing premature wear of the electrodes 44. This method is therefore particularly economical since it allows reducing maintenance interventions on the reactor 40.

[0127] The present invention also relates to the following items:

[0128] Item 1. Method for decontaminating a preform (14) made of thermoplastic material by exposing at least a portion of the preform (14) to a reactive species (RS) obtained by mixing a precursor agent (AP) with a plasma (P), the plasma (P) being generated by injecting a carrier gas (G) in a reactor (40),

[0129] It is characterized in that the mixing between the precursor agent (AP) and the plasma (P) takes place only outside the reactor (40) before coming into contact with the preform (14).

[0130] Item 2. A method according to the preceding item, characterized in that at least one inner surface (28) of the preform (14) is exposed to a reactive substance (RS), which is confined inside the preform (14) for a duration determined by a confinement device.

[0131] Item 3. A method according to the previous item, characterized in that the method is implemented while the preform (14) is being transported through an apparatus (10) for manufacturing a container from the preform (14), the apparatus (10) comprising a heating furnace (32) for the preform (14), the reactive substance (RS) being injected into the preform (14) before or during the heating of the preform (14) in the heating furnace (32), the reactive substance (RS) being confined in the preform (14) until it leaves the heating furnace (32).

[0132] Item 4. A method according to the preceding item, characterized in that the reactive substance (RS) is confined in the preform (14) by means of a chuck (39) which grasps the preform (14) by its neck so that it can move in the heating furnace (32).

[0133] Item 5. A method according to any one of the preceding items, characterized in that the precursor agent (AP) is mixed with the plasma (P) at the outlet of the reactor (40).

[0134] Item 6. The method according to any one of the preceding items, characterized in that the precursor reagent (AP) comprises hydrogen peroxide.

[0135] Item 7. The method according to any one of the preceding items, characterized in that the precursor agent (AP) is in a vapor state when it is mixed with the plasma (P).

[0136] Item 8. The method according to any one of items 1 to 6, characterized in that the precursor agent (AP) is in the form of a mist when it is mixed with the plasma (P).

[0137] Item 9. The method according to any one of the preceding items, characterized in that the carrier gas (G) is formed from molecular oxygen.

[0138] Item 10. The method according to any one of items 1 to 8, characterized in that the carrier gas (G) is air.

[0139] Item 11. The method according to any one of the preceding items, wherein the reactive substance comprises one or more of the following chemical components:

[0140] - Reactive oxygen species (ROS);

[0141] - reactive nitrogen species (RNS);

[0142] -Ozone (O3).

[0143] Item 12. A decontamination device (50) for implementing the method according to any one of Items 1 to 11, characterized in that the decontamination device (50) comprises:

[0144] a decontamination conduit (52) connected at its upstream end to a source (56) of a precursor agent (AP) and at its downstream end to at least one injection nozzle (60) intended to inject a reactive substance (RS) onto at least a portion of the preform (14), this reactive substance (RS) being obtained by decomposition of the precursor agent (AP) when it is mixed with the plasma (P);

[0145] a plasma reactor (40) connected to a source (64) of carrier gas (G) and having an outlet (66) connected to the decontamination duct (52) via a branch (68) which divides the decontamination duct (52) into an upstream section (52A) in which the undecomposed precursor reagent (AP) is to circulate, and a downstream section (52B) in which the reactive species (RS) generated by the decomposition of the precursor reagent (AP) when it is mixed with the plasma (P) are to circulate.

[0146] Item 13. The device (50) according to the previous item, characterized in that the plasma reactor (40) is a cold plasma reactor, such as a corona discharge reactor or a dielectric barrier discharge reactor.

[0147] Item 14. An apparatus (50) according to any one of items 12 or 13, characterized in that the decontamination line (52) includes an evaporator (72) of a precursor reagent (AP) which is arranged upstream of the branch (68) having the plasma reactor (40).

[0148] Item 15. The device (50) according to any one of items 12 or 13, characterized in that the decontamination conduit (52) comprises a precursor reagent (AP) atomization member arranged upstream of the branch (68).

Claims

1. A method for decontaminating a preform (14) made of thermoplastic material by exposing at least a portion of the preform (14) to a reactive species (RS) obtained by mixing a precursor agent (AP) with a plasma (P) generated by injecting a carrier gas (G) in a capacitive reactor (40), the capacitive reactor (40) comprising a reaction chamber (42) in which there are two electrodes (44) electrically connected to a direct or alternating current generator (46) allowing a strong potential difference to be applied between the two electrodes (44); It is characterized by: Mixing between the precursor agent (AP) and the plasma (P) occurs just outside the reactor (40) before contact with the preform (14), and the precursor agent (AP) comprises hydrogen peroxide.

2. The method according to the preceding claim, characterized in that At least one interior surface (28) of the preform (14) is exposed to a reactive substance (RS) which is confined within the interior of the preform (14) for a duration determined by a confinement device.

3. The method according to the preceding claim, characterized in that The method is carried out while a preform (14) is conveyed through an apparatus (10) for manufacturing containers from the preform (14), the apparatus (10) comprising a heating furnace (32) for the preform (14), a reactive substance (RS) being injected into the preform (14) before or during heating of the preform (14) in the heating furnace (32), the reactive substance (RS) being confined in the preform (14) until it leaves the heating furnace (32).

4. Method according to the preceding claim, characterized in that The reactive substance (RS) is confined in the preform (14) by means of a chuck (39) which grasps the preform (14) by its neck to enable its movement in the heating furnace (32).

5. The method according to any one of the preceding claims, characterized in that The precursor agent (AP) is mixed with the plasma (P) at the outlet of the reactor (40).

6. The method according to any one of the preceding claims, characterized in that The precursor reagent (AP) includes hydrogen peroxide.

7. The method according to any one of the preceding claims, characterized in that The precursor agent (AP) is in a vapor state when it is mixed with the plasma (P).

8. The method according to any one of claims 1 to 6, characterized in that The precursor agent (AP) is in the form of a mist when it mixes with the plasma (P).

9. The method according to any one of the preceding claims, characterized in that The carrier gas (G) is formed from molecular oxygen.

10. The method according to any one of claims 1 to 8, characterized in that The carrier gas (G) was air.

11. The method according to any one of the preceding claims, characterized in that Reactive substances contain one or more of the following chemical components: - Reactive oxygen species (ROS); - reactive nitrogen species (RNS); -Ozone (O3).

12. A decontamination device (50) for carrying out the method according to any one of claims 1 to 11, characterized in that The decontamination device (50) comprises: a decontamination conduit (52) connected at its upstream end to a source (56) of a precursor agent (AP) and at its downstream end to at least one injection nozzle (60) intended to inject a reactive substance (RS) onto at least a portion of the preform (14), this reactive substance (RS) being obtained by decomposition of the precursor agent (AP) when it is mixed with the plasma (P); a plasma reactor (40) connected to a source (64) of carrier gas (G) and having an outlet (66) connected to the decontamination duct (52) via a branch (68) which divides the decontamination duct (52) into an upstream section (52A) in which the undecomposed precursor reagent (AP) is to circulate, and a downstream section (52B) in which the reactive species (RS) generated by the decomposition of the precursor reagent (AP) when it is mixed with the plasma (P) are to circulate.

13. Device (50) according to the preceding claim, characterized in that The plasma reactor (40) is a cold plasma reactor, such as a corona discharge reactor or a dielectric barrier discharge reactor.

14. The device (50) according to any one of claims 12 or 13, characterized in that The decontamination line (52) comprises an evaporator (72) of a precursor agent (AP) arranged upstream of the branch (68) with the plasma reactor (40).

15. The device (50) according to any one of claims 12 or 13, characterized in that The decontamination conduit (52) comprises a precursor reagent (AP) atomization means arranged upstream of the branch (68).

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