Method for decontaminating preform with reactive species obtained by mixing precursor agent and plasma

Abstract

To provide a method for decontaminating a preform made of thermoplastic material.SOLUTION: The invention relates to a method for decontaminating a preform (14) by exposing at least one part of the preform (14) made of thermoplastic material to 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) into a reactor (40), characterized in that the mixing of the precursor agent (AP) and the plasma (P) is carried out exclusively outside of the reactor (40) before coming in contact with the preform (14). The invention also relates to a decontamination device (50) for implementing the method.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to a method for decontaminating a preform of a thermoplastic material by exposing at least a part of the preform to reaction species obtained by mixing a precursor with a plasma generated by injecting a carrier gas into a reactor.

Background Art

[0002] In the field of food packaging, it is known to perform a decontamination treatment for disinfecting or sterilizing at least some parts of a container intended to receive food, particularly the interior and the neck of the container.

[0003] The decontamination treatment applied aims to completely eliminate or at least reduce the presence of microbial organisms or microorganisms such as pathogenic bacteria, bacteria, spores, molds, etc. in order to enable the preservation of the product.

[0004] "Container" means a hollow body such as a bottle, a flask, a pot, etc., all of which are containers obtained by deforming a thermoplastic preform, which is most often pre-manufactured by injection molding. The preform particularly comprises a body intended to be formed into its final shape in the manufacturing process, and also comprises a neck already having the final shape.

[0005] Among thermoplastic materials, PET (polyethylene terephthalate) is most commonly used for these applications.

[0006] During the manufacture of the container, the body of the preform is first thermally conditioned in a furnace to soften its constituent material. For this purpose, the furnace particularly comprises a heating device by means of the emission of heating electromagnetic radiation, for example by infrared lamps. The preform thus softened is then deformed into a container by blowing at least one fluid into a mold under pressure, with or without drawing. The neck of the preform is kept at a sufficiently cold temperature so as not to deform during the container manufacturing process.

[0007] As a variant, the injection-molded preform is directly deformed into a container without the need for preliminary thermal conditioning in that case.

[0008] In the prior art, the decontamination of preforms is carried out by a "chemical route" using in particular hydrogen peroxide (H2O2) or any other product having similar properties, i.e. a sterilizing agent containing a bactericide, a virucide, a fungicide, etc. More particularly, it is a so-called "precursor" substance that can be decomposed into reactive species, in particular reactive oxygen species (ROS). Reactive oxygen species include in particular hydroxyl radicals, superoxide anions, hydroxyl ions, etc. Bacteria and viruses are very effectively exterminated by contact with reactive oxygen species.

[0009] The decomposition of the precursor substance into reactive oxygen species is carried out, for example, by heating the precursor substance to a high temperature for at least a predetermined minimum period.

[0010] Sterilization using reactive oxygen species is extremely effective. Also, since the final residue of the chemical reaction consists only of water and dioxygen, it is particularly harmless to consumers.

[0011] Therefore, it is known to inject a precursor substance such as a solution of hydrogen peroxide and water into the preform in a vapor state before the preform enters the furnace. The vapor condenses when it comes into contact with the inner wall of the preform. Then, when the preform enters the furnace, the condensed precursor substance is heated by the heating device of the furnace simultaneously with the preform body. The heat is generally sufficient to partially decompose the precursor substance contained in the preform.

[0012] Therefore, the preform contains a sterile atmosphere throughout the manufacture of the container until the container is filled.

[0013] However, the amount of heat received by the precursors contained in the preform while the preform is being heated is generally not sufficient to decompose all of the precursors into active oxygen species. The amount of heat transferred to the preform depends, for example, on the size of the preform, the shape of the final container, the color of the preform, and the like.

[0014] To solve this problem, the preform can be heated in the furnace longer than necessary so that most of the precursors are decomposed into active oxygen species.

[0015] However, it is not always possible to heat the precursors sufficiently without degrading the preform.

[0016] Furthermore, the need to continue heating the preform even though the body of the preform has already reached the desired temperature for forming into the final container leads to an increase in the manufacturing cost of the container.

[0017] Also, although the residues from the reaction of the active oxygen species are harmless, the precursors, especially hydrogen peroxide, can become toxic if the dosage exceeds a certain amount. This can cause problems, especially when the container is intended to contain food. For this reason, several countries have imposed strict standards regarding the residual amount of precursors allowed in the container after filling. For example, the precursors contained in the container must be less than 0.5 ppm.

[0018] To achieve this purpose and also considering the above heating problems, it may be necessary to dilute the precursors with a harmless solvent, such as water, to reduce the amount of precursors injected into the container.

[0019] However, if the content of the precursors is low, the effectiveness of the sterilization treatment may be significantly reduced.

[0020] The decomposition of precursors using plasma has already been proposed. For this purpose, it is known to inject a precursor mixed with a carrier gas such as air into a capacitively coupled plasma reactor. This type of reactor comprises a reaction chamber containing two electrodes across which a large potential difference is applied. Thereby, the carrier gas is ionized and the decomposition of the precursor into reactive oxygen species is activated. This solution preferably enables almost all of the precursor to be decomposed into reactive oxygen species even before contacting the object to be decontaminated.

[0021] It is already known that the carrier gas decomposes at least partially into reactive species. However, due to the presence of the precursor, the concentration of the reactive species becomes extremely high. Subsequently, the reaction chamber has a high concentration of reactive oxygen species. These components, especially hydroxyl ions, have a very strong oxidizing power and as a result are particularly corrosive. Therefore, regardless of the material they are made of, the electrodes are rapidly consumed and have to be replaced very frequently.

SUMMARY OF THE INVENTION

PROBLEM TO BE SOLVED BY THE INVENTION

[0022] The present invention proposes a method for decontaminating a preform of a thermoplastic material by exposing at least a part of the preform to reactive species obtained by mixing a precursor with plasma generated by injecting a carrier gas into a reactor.

MEANS FOR SOLVING THE PROBLEM

[0023] The method of the present invention is characterized in that the mixing of the precursor and the plasma is carried out only outside the reactor before contacting the preform.

[0024] Therefore, the electrodes of the reactor never come into contact with either the precursor or the reactive species obtained by the decomposition of the precursor upon contact with the plasma.

[0025] According to another characteristic specific to the method of the present invention, At least one inner surface (28) of the preform is exposed to reactive species, which are confined within the preform for a time determined by the confinement means. The method comprises a furnace for heating the preform, and the method is carried out while the preform is being transferred through a plant for manufacturing containers from the preform. The reactive species are injected into the preform before or during the heating of the preform in the heating furnace, and the reactive species are confined within the preform until it exits the heating furnace. The reactive species are confined within the preform by confinement means that will be fixed inside the neck of the preform. The reactive species are confined within the preform by confinement means that will be fixed outside the neck of the preform.

[0026] This confinement means fixed inside or outside the neck enables the interior of the preform to be isolated from its external environment. The reactive species are confined within the preform using a mandrel that grips the preform by its neck so that the preform can be moved within the heating furnace. The precursor is mixed with plasma upon release from the reactor. The precursor contains hydrogen peroxide. The precursor is in a vapor state when mixed with the plasma. The precursor is in the form of a mist when mixed with the plasma. The carrier gas is formed by dioxygen. The carrier gas is air. The reactive species are the following chemical components, Reactive oxygen species (ROS), Reactive nitrogen species (RNS), Ozone (O3) including one or more of.

[0027] The present invention also relates to a decontamination device for applying a decontamination method carried out according to the teachings of the present invention.

[0028] The decontamination device is A decontamination line having an upstream end connected to a source of a precursor and a downstream end connected to at least one injection nozzle intended to project reactive species obtained by decomposition of the precursor upon mixing with a plasma onto at least a part of a preform, A plasma reactor connected to a source of a carrier gas, the outlet of which is connected to the decontamination line by a branch pipe that divides the decontamination line into an upstream section intended for internal circulation of the undecomposed precursor and a downstream section intended for internal circulation of active oxygen species generated by decomposition of the precursor upon mixing with the plasma, characterized by comprising.

[0029] According to other features particular to the decontamination device of the present invention, the plasma reactor is a low-temperature plasma reactor such as a corona discharge reactor or a dielectric barrier discharge reactor, the decontamination line comprises an evaporator for the precursor disposed upstream of the branch pipe having the plasma reactor, the decontamination line comprises a precursor atomizing device disposed upstream of the branch pipe.

[0030] Other features and advantages of the present invention will become apparent upon reading the following detailed description. For the purpose of understanding, reference is made to the accompanying drawings.

Brief Description of the Drawings

[0031]

Figure 1

Figure 2

Figure 3

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Figure 5

Figure 6

DETAILED DESCRIPTION OF THE INVENTION

[0032] In the following description, elements having the same structure or similar functions are denoted by the same reference numerals.

[0033] FIG. 1 shows a plant 10 for mass production of containers. The plant 10 makes it possible to manufacture a final container 12 by molding a preform 14.

[0034] FIG. 2 shows an example of a preform 14 made of a thermoplastic material. Here, the preform 14 is made of polyethylene terephthalate (PET).

[0035] The preform 14 is generally obtained by injection molding of plastic and has characteristics (dimensions, material distribution, etc.) determined by the final container 12 to be obtained, particularly its shape or its capacity.

[0036] The preform 14 has an axisymmetric shape with respect to a main axis "A" shown vertically in FIG. 2. The preform 14 particularly includes a tubular body 16 whose lower end is closed by a bottom 18 and whose upper part is open by an upper opening 20 defined radially by a neck 22. The main axis "A" of the preform 14 passes through the center of the neck 22.

[0037] The neck 22 of the preform 14 has its final shape at the end of the injection molding manufacture of the preform 14 and corresponds to the neck of the final container 12. The edge 24 of the upper free end of the neck 22, also called the lip, circumferentially defines a circular opening 20 that constitutes the only access to the interior of the preform 14.

[0038] In the example shown in FIG. 2, the neck 22 comprises a flange 26 that extends radially and projects outward.

[0039] The body 16, shown in dashed lines in FIG. 2, is defined by a tubular wall having an inner surface 28 located inside the preform 14 and an outer surface 30 located outside.

[0040] The preform 14 has, for example, an opening 20 with an inner diameter of about 20 mm and an overall height of about 90 mm. The thickness of the wall defining the body 16 is, for example, about 3 mm. These values are given as non-limiting examples, and the preform 14 may have different dimensions while maintaining the same overall proportions.

[0041] Referring again to FIG. 1, the manufacturing plant 10 mainly comprises a heating furnace 32, and the heating furnace 32 comprises a device 33 for heating the body 16 of the preform 14 above the glass transition temperature at which the material becomes malleable. In order to ensure that the neck 22 of the preform 14 does not deform during the manufacturing process, the furnace 32 comprises means for keeping the temperature of the neck 22 below its glass transition temperature.

[0042] The heating furnace 32 comprises a device 35 for conveying the preforms 14 in a row. The conveying device 35 comprises individual supports that circulate in a closed circuit within the heating station 10.

[0043] In the embodiment shown in FIGS. 2 to 4, the transfer device 35, in this case, comprises a plurality of transfer elements 37 that form the links of a closed transfer chain. Each transfer element 37 carries at least one individual support. Each individual support comprises a mandrel 39. The mandrel 39 is intended to be fitted into the neck of the preform 14. According to an example of a known embodiment, the mandrel 39 is preferably provided with elastic means (not shown), such as an O-ring seal made of an elastic material (such as an elastomer), having an outer diameter equal to or slightly larger than the inner diameter of the neck of the preform 14, so as to lift the preform 14 by friction against the inner wall of the neck when the mandrel 39 is inserted, and also to isolate the interior of the preform from its external environment to ensure the quality of decontamination.

[0044] Generally, each mandrel 39 is provided with means, such as a pinion 41 that interacts with a fixed belt (not shown), that enables the preform 14 to rotate about its main axis during displacement along at least a part of the transfer path in order to enable uniform heating of the body of the preform 14. This type of transfer device having a rotating mandrel 39 is sometimes referred to as a "rotating plate".

[0045] The manufacturing plant 10 also comprises an injection station 34, and the injection station 34 comprises a forming unit 36 for receiving the preform 14. The preform 14 is intended to be formed into the final container 12, for example, by being drawn into and injected into a mold (not shown) of the forming unit 36. The forming unit 36 is attached to a carousel 38, which enables the preform 14 to be moved from an inlet point to an outlet point during deformation into the final container 12.

[0046] During the manufacturing process, the preform 14, and then the container 12, are moved in a row along a predetermined production path indicated by the thick line in FIG. 1 by a conveyor. The conveyor comprises individual support means (not shown) for each hollow body in the state of the preform 14 or the container 12. These conveyors are well known in the prior art and will not be described in detail here.

[0047] The production of the container 12 is not carried out in a clean room even if the container is for food use. Therefore, it is necessary to provide means for decontaminating the preform 14.

[0048] The present invention proposes a method for decontaminating a preform 14 by exposing at least a part of the preform 14 made of a thermoplastic material to reactive species "RS" obtained by mixing a precursor "AP" and a plasma "P". More specifically, they are reactive species having sterilizing properties. The decontamination method is preferably applied during the operation of the preform in a plant for manufacturing the container, and more specifically during the transfer of the preform through the manufacturing plant.

[0049] The reactive species particularly include the following chemical components, Reactive oxygen species, also abbreviated as ROS, including hydroxyl radicals, superoxide anions, hydroxyl ions, perhydroxyl radicals, etc. Reactive nitrogen species, also abbreviated as RNS, particularly including nitric oxide (NO). Ozone, consisting of one or more of them.

[0050] The precursor AP is defined as a substance that can be decomposed into reactive species RS by exposure to plasma P. Preferably, the precursor AP is selected so as to be completely decomposed into reactive species RS so that it is not necessary to wash the container 12 at the end of the manufacturing process.

[0051] The precursor AP is formed, for example, by hydrogen peroxide (H2O2), particularly a solution of hydrogen peroxide and water.

[0052] The concentration of hydrogen peroxide in the aqueous solution is, for example, 5% to 35%. Hydrogen peroxide and / or water are likely to decompose very rapidly into a large number of reactive oxygen species (ROS).

[0053] In addition, the reaction species RS obtained by exposing hydrogen peroxide to gas in the state of plasma P is stable for a sufficient time to enable decontamination through the manufacturing process of the preform 14. The reaction between different reaction species RS is, in fact, advantageous for the promotion of new reaction species RS.

[0054] Plasma P is generated by injecting a carrier gas into the reactor 40. The carrier gas is generally dioxygen (O2), and in this case, the reaction species RS generated by mixing the plasma P and the precursor AP are mainly active oxygen species.

[0055] As a modification, the carrier gas may also be formed from another pure gas or from another composition, such as air. When the carrier gas is formed from a gas containing nitrogen such as air, the plasma contains reactive nitrogen species and active oxygen species. These reaction species react with the precursor AP during mixing to form new active oxygen species. Therefore, the reaction species resulting from the mixing include a mixture of active oxygen species and reactive nitrogen species.

[0056] The reactor 40 can generate a cold plasma P obtained at atmospheric pressure in this case. The plasma P is obtained, for example, by supplying electromagnetic energy to the carrier gas G. For this purpose, the reactor 40 is, for example, a capacitive reactor 40 mainly including a reaction chamber 42, and the reaction chamber has two electrodes 44 electrically connected to a direct current or alternating current generator 46, and the direct current or alternating current generator 46 can apply a large potential difference between the two electrodes 44.

[0057] According to the first embodiment (not shown), it is a corona effect reactor capable of generating an electric arc between two electrodes when a potential difference greater than the breakdown voltage is applied between the two electrodes.

[0058] According to a second embodiment shown in FIG. 3, it is a dielectric barrier discharge (DBD) reactor 40. In this reactor 40, a barrier 48 made of a dielectric material is inserted between two electrodes 44. This makes it possible to prevent, in particular, the generation of an electric arc between the two electrodes 44.

[0059] When the electrode 44 is brought into contact with the precursor AP, it has been found that premature wear of the electrode 44 due to oxidation is likely to occur.

[0060] In order to solve this problem while maintaining the advantage of the generation of reactive species RS by the plasma P, the present invention proposes that the mixing of the precursor AP and the plasma P should be carried out only outside the reaction chamber 42 of the reactor 40 before contacting the preform 14. Therefore, neither the precursor AP nor the reactive species RS obtained by the contact of the precursor AP and the plasma P ever contacts the electrode 44. Therefore, premature corrosion of the electrode 44 is avoided.

[0061] Furthermore, by generating the mixture before contacting the preform 14, it becomes possible to decompose almost all of the precursor AP. Therefore, the residual content of the precursor AP in the container 12 manufactured from the preform 14 thus treated can preferably be ignored.

[0062] The precursor AP is preferably directly mixed with the plasma P during discharge from the reactor 40. Therefore, the bulk of the carrier gas G is still in the state of plasma when mixed with the precursor AP.

[0063] In order to promote the generation of reactive species RS, the precursor AP is evaporated before being mixed with the plasma P. Therefore, the precursor AP is in a vapor state when mixed with the plasma P.

[0064] In a variant, the precursor AP is mixed with the plasma in the form of a mist.

[0065] Therefore, as shown in FIG. 4, the method of the present invention includes a first step E1 of generating plasma P by a reactor 40, a second step E2 of then mixing a precursor AP with the plasma P outside the reactor 40, and subsequently a third step E3 of spraying the reaction species RS obtained in the second step E2 onto the portion of the preform 14 to be decontaminated.

[0066] Also, the inner surface 28 and the outer surface 30 of the preform 14 can be decontaminated by this method.

[0067] However, this method is particularly suitable for decontaminating the inner surface 28 of the preform 14 that is difficult to access and the neck portion 22 of the preform 14 that is not heated much by the furnace 32.

[0068] In the case of decontaminating the inside of the preform 14, the method preferably includes a step E4 of confining the reaction species RS inside the preform 14 for a time determined by measuring from their injection, for example, less than 12 seconds, although this is not always the case.

[0069] When the reaction species RS are injected into the preform 14 upstream of the heating furnace 32, the predetermined time corresponds to the time it takes for the preform 14 to exit the heating furnace 32, for example, less than 12 seconds. In this case, the confinement of the reaction species RS is performed using a mandrel 39 that closes the preform 14 while passing through the heating furnace 32.

[0070] This confinement ensures that the reaction species are localized at the location where decontamination is required and prevents the reaction species from escaping into the furnace. The dispersion of these reaction species may cause oxidation of the metal parts present in the furnace.

[0071] Also, this confinement ensures that the reaction species remain in contact with the space defined by the inner wall of the preform for a certain time, guaranteeing the effectiveness of the decontamination step.

[0072] When the reactive species RS is injected into the preform 14 at another location in the plant, for example, downstream of the heating furnace 32, the confinement may be effected by physically blocking the preform 14 using a stopper or by projecting a laminar air flow F directly towards the neck inside the preform 14 parallel to the axis of the preform 14. The air flow F must then have a cross-sectional dimension larger than the cross-sectional dimension of the neck of the preform 14 in order to prevent an air flow that expels the reactive species instead of confining the reactive species, as represented by the bundle of parallel arrows F in FIG. 6.

[0073] FIG. 3 shows an example of a decontamination device 50 for applying a decontamination method implemented in accordance with the teachings of the present invention.

[0074] The decontamination device 50 comprises a decontamination line 52, the upstream end 54 of which is connected to a source 56 of a precursor AP and the downstream end 58 of which is connected to an injection nozzle 60 intended to inject the reactive species RS onto or into the preform 14. In the example shown, it is the nozzle 60 that is intended to inject the reactive species RS into the preform 14.

[0075] The source 56 of the precursor AP sends the precursor AP under a pressure that allows the precursor AP to flow to the nozzle 60.

[0076] The decontamination device 50 also comprises a plasma P reactor 40. The reactor 40 comprises a reaction chamber 42, at least one inlet orifice 62 of the reaction chamber 42 being connected to a source 64 of a carrier gas G and the outlet 66 of the reaction chamber 42 being connected to an intermediate portion of the decontamination line 52 by a branch pipe 68. The branch pipe 68 divides the decontamination line 52 into an upstream section 52A intended for the internal circulation of the undissociated precursor AP and a downstream section 52B intended for the internal circulation of the reactive species RS generated by the decomposition of the precursor AP upon mixing with the plasma P.

[0077] The carrier gas G sent by the source 64 is, for example, dioxygen or air.

[0078] The carrier gas G may be injected under a pressure that allows it to flow to the outlet 68.

[0079] A check valve 70 is provided at the outlet of the reaction chamber 42 to prevent the precursor AP or the reaction species RS obtained by the decomposition of the precursor AP from being erroneously returned to the reaction chamber 42.

[0080] As a variant, when the plasma (P) is generated by injecting the carrier gas into the reactor, the pressure inside the reactor is greater than the pressure inside the decontamination line (52). As a result, during the application of this decontamination method, since the pressure inside the reactor is greater than the pressure inside the decontamination line (52), any increase in the precursor (AP) and / or reaction species inside the reactor is avoided, and thus any oxidation of the reaction species is prevented. For this purpose, preferably, the plasma is generated before and after the evaporation step of the precursor in the decontamination line (52).

[0081] The reaction chamber 42 contains two spaced electrodes 44. The electrodes 44 are connected to a current generator 46. The electrodes 44 are arranged such that the carrier gas G circulating from the inlet orifice 62 to the outlet orifice 66 passes through the space provided between the two electrodes 44. The potential difference applied between the electrodes 44 is sufficient to convert the carrier gas G into plasma P.

[0082] Here, it is the reactor 40 having a dielectric barrier discharge 48. A barrier 48 of a dielectric material is inserted between the two electrodes 44.

[0083] When the precursor AP is sent in a liquid state by a source 56 of the precursor AP, the decontamination line comprises an evaporator 72 of the precursor AP arranged upstream of a branch pipe having the reactor 40 of the plasma P. The precursor AP is heated, for example, using electrical resistance.

[0084] As a variant, it is a heat exchanger.

[0085] According to another variant of the invention, the evaporator is replaced by an atomization device of the precursor AP arranged upstream of the branch pipe.

[0086] In the example shown in FIG. 1, the decontamination device 50 is configured to process the preform 14 upstream of the furnace 32. The heat supplied by the furnace makes it possible, in fact, to accelerate the reaction between the reactive species RS and the microbial agent present on the surface of the preform 14.

[0087] However, it is also possible to arrange the decontamination device 50 at other locations of the manufacturing plant 10, for example downstream of the furnace 32.

[0088] It has been found that the decontamination inside the preform 14 is more effective when the reactive species RS are trapped inside the preform 14 after being injected into the preform 14.

[0089] During the use of the decontamination device 50, a carrier gas G is supplied to the reactor 40 to generate a plasma P of this carrier gas G. The plasma P thus obtained is injected into the decontamination line 52 at the level of the branch pipe 68.

[0090] At the same time, the precursor AP evaporated by the evaporator 72 is supplied to the line 52. The precursor AP thus evaporated is then mixed with the plasma P at the level of the branch pipe without entering the reactor 40. This mixing activates the decomposition of the precursor AP into the reactive species RS. The reactive species RS thus obtained are then projected inside the preform 14 to decontaminate the surface of the preform 14 to be decontaminated, in this case its inner surface 28.

[0091] When carrying out this method, all the precursors introduced into the decontamination line 52 may be completely activated by the plasma.

[0092] In certain embodiments, it is also possible that only a portion of the precursor introduced into the decontamination line 52 is activated by the plasma. In this embodiment, the precursor is activated in two complementary ways. There is a first amount of precursor that is directly activated by the plasma, and an amount of precursor that is not directly activated is injected into the preform. The amount of precursor that is not directly activated is injected into the preform in the form of vapor and then condenses on the inner wall of the body of the preform and is to be activated using a heating element, i.e., an IR lamp or a laser diode.

[0093] Decontamination of the preform by the precursor, in particular by hydrogen peroxide activated by heating, starts when the precursor reaches a certain temperature.

[0094] In this embodiment, the decontamination method comprises two activation steps of the precursor, i.e., one activation step by plasma that achieves activation of the precursor almost instantaneously. That is, decontamination of the preform starts as soon as the mixture activated by the plasma comes into contact with the preform, in particular the body of the preform. This is followed by a second activation step of the amount of precursor that has not been previously activated.

[0095] As a result, the reaction rates of the two activation steps are different. The first activation step has a reaction rate that is faster than the reaction rate of the second activation step.

[0096] Preferably, depending on the amount of precursor injected, it is possible to combine the ratios of the two activation steps of the precursor. This makes it possible to increase the overall reaction rate of the decontamination of the preform and thus the degree of its decontamination.

[0097] Also, by having two activation steps, it becomes possible to manage the amount of residual precursor remaining in the preform at the time of discharge from the furnace, i.e., at the end of decontamination.

[0098] The method according to the present invention, and the apparatus 50 for carrying it out, very preferably make it possible to decontaminate the preform 14 using a precursor substance AP such as hydrogen peroxide while obtaining a final container in which the residual amount of the precursor substance AP is negligible. Therefore, it is not necessary to wash the container 12 at the end of the manufacturing process.

[0099] Furthermore, by mixing the plasma P and the precursor substance AP, it becomes possible to obtain a result that is as satisfactory as mixing in the reactor without causing premature wear of the electrode 44. Therefore, the method is particularly economical because it makes it possible to reduce the maintenance work of the reactor 40.

Claims

1. A method for decontaminating a preform (14) made of a thermoplastic material by exposing at least a portion of said preform (14) to reactive species (RS) obtained by mixing a precursor (AP) with a plasma (P) generated by injection of a carrier gas (G) into a reactor (40), comprising the steps of: A method characterized in that the mixing of the precursor (AP) with the plasma (P) takes place exclusively outside the reactor (40) before contacting the preform (14).

2. 2. The method of claim 1, wherein at least one inner surface (28) of the preform (14) is exposed to a reactive species (RS), the reactive species (RS) being confined within the preform (14) for a time period determined by a confinement means.

3. 3. The method according to claim 2, characterized in that the method is carried out during the transport of the preform (14) through a manufacturing plant (10) for producing containers from the preform (14), the plant comprising a furnace (32) for heating the preform (14), and the reactive species (RS) are injected into the preform (14) before or during heating in the furnace (32), the reactive species (RS) being confined within the preform (14) until discharge from the furnace (32).

4. 4. The method according to claim 3, characterized in that the reactive species (RS) are confined in the preform (14) by means of a mandrel (39) which grips the preform (14) by its neck and makes it possible to move it in the furnace (32).

5. A method according to any one of claims 1 to 4, characterized in that the precursor (AP) is mixed with the plasma (P) on exit from the reactor (40).

6. A method according to any one of claims 1 to 5, characterized in that the precursor (AP) comprises hydrogen peroxide.

7. A method according to any one of claims 1 to 6, characterized in that the precursor (AP) is in the vapour state when mixed with the plasma (P).

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

9. 9. The method according to claim 1, wherein the carrier gas (G) is formed by dioxygen.

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

11. The reactive species are the following chemical components: Reactive oxygen species (ROS), Reactive Nitrogen Species (RNS), Ozone (O ３ ), The method according to any one of claims 1 to 10, characterized in that it comprises one or more of the following:

12. A decontamination device (50) for carrying out the method according to any one of claims 1 to 11, comprising: a decontamination line (52) whose upstream end is connected to a source (56) of precursor (AP) and whose downstream end is connected to at least one injection nozzle (60) intended to project reactive species (RS) obtained by decomposition of the precursor (AP) when mixed with the plasma (P) onto at least a portion of the preform (14); a plasma reactor (40) connected to a source (64) of carrier gas (G) and having an outlet (66) connected to the decontamination line (52) by a branch pipe (68) dividing the decontamination line (52) into an upstream section (52A) intended for the circulation of undecomposed precursors (AP) and a downstream section (52B) intended for the circulation of reactive species (RS) generated by decomposition of the precursors (AP) when mixed with the plasma (P); An apparatus (50) comprising:

13. The device (50) according to claim 12, characterized in that the plasma reactor (40) is a low-temperature plasma reactor, such as a corona discharge reactor or a dielectric barrier discharge reactor.

14. 14. Apparatus (50) according to claim 12 or 13, characterized in that the decontamination line (52) comprises a precursor (AP) vaporizer (72) arranged upstream of a branch pipe (68) with the plasma reactor (40).

15. 14. Apparatus (50) according to claim 12 or 13, characterized in that the decontamination line (52) comprises a precursor (AP) atomization device arranged upstream of the branch pipe (68).

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