PROCESS FOR DECONTAMINATING THE INTERNAL FACE OF PREFORMS

Abstract

The invention relates to a method for decontaminating an internal face (26) of a neck (18) of a preform (12) made of thermoplastic material moving along a production path (34) in an installation (10) for manufacturing containers (11), each preform (12) being held by an individual holding member (58, 66), said decontamination method successively comprising at least: - a treatment step (E1) consisting of exposing at least the internal face (26) of the neck (18) to a sterilizing jet (54) comprising a sterilizing agent in a first treatment zone (56) of the production path (34); - a step (E2) of activating the sterilizing agent consisting of directly exposing the internal face (26) of the neck (18) thus covered with sterilizing agent to ultraviolet radiation (61), in a second activation zone (62) of the production path (34) located downstream of the zone (56) of treatment. Figure for abstract: Figure 1.

Description

Title of the invention: METHOD FOR DECONTAMINATING THE INTERNAL FACE OF PREFORMS TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to a method for decontaminating an internal face of a neck of a thermoplastic preform moving along a production path in a container manufacturing installation.

[0002] TECHNICAL BACKGROUND OF THE INVENTION

[0003] It is known to produce containers from thermoplastic material, such as polyethylene terephthalate (PET), by a preform stretch-blow molding process.

[0004] In general, a preform has an axisymmetric shape. The preform has a neck which already has its final shape, while a body of the preform is intended to be deformed during the forming process. The main axis of the preform passes through the center of the neck.

[0005] To enable its deformation, the body of the preform is heated beyond a glass transition temperature making it possible to make the wall of the body malleable by significantly reducing its elastic limit. On the contrary, the neck is maintained at a temperature below the glass transition temperature to prevent its deformation.

[0006] When forming the container, a compressed forming fluid is injected at a blowing pressure into the body of the preform so as to "inflate" the body of the preform until it reaches its final shape.

[0007] Examples of methods for decontaminating a thermoplastic preform intended to be transformed into a container in a manufacturing facility are known from the state of the art.

[0008] In the state of the art, a distinction is made, on the one hand, between decontamination methods intended for the decontamination of the internal face of the preform and, on the other hand, between decontamination methods intended for the decontamination of the external face of the preform, in particular the neck of the preform.

[0009] Decontamination of the inner face of the neck is a particularly important operation. Sufficient decontamination of this face is a crucial criterion, particularly for the manufacture of containers intended to contain food products. However, the inner face of the neck is difficult to access.

[0010] Chemical decontamination processes are known, obtained by exposing the preform to a sterilizing agent such as hydrogen peroxide (H2O2) or peracetic acid. Such a chemical agent has a strong oxidizing power which helps eliminate some of the microorganisms (viruses, germs, spores, etc.) that are exposed to it.

[0011] However, it has been found that such a chemical decontamination process is not sufficiently effective to sufficiently decontaminate the preforms, particularly when they are intended for food or pharmaceutical use.

[0012] To improve the effectiveness of the sterilizing agent, it is known to increase its action considerably by heating it, in particular by exposing it to infrared radiation. This heating in fact decomposes the sterilizing agent into even more oxidizing species, such as free radicals. It is then said that the sterilizing agent has been "activated".

[0013] However, the fact of not being able to heat the neck of the preform to activate the sterilizing agent constitutes an obstacle for the person skilled in the art.

[0014] As an alternative to chemical decontamination, decontamination by irradiation using ultraviolet radiation is also known as an alternative to activated chemical decontamination.

[0015] The thermoplastic materials constituting the preforms are generally opaque to ultraviolet radiation. The decontamination of the external face of the neck obtained with ultraviolet radiation is limited due to its superficial nature, the ultraviolet radiation not penetrating deeply. Therefore, it is necessary to directly expose the faces to be decontaminated to ultraviolet radiation. This therefore implies being able to access the faces to be treated. In the case of decontamination of the internal face of the neck of the preforms, this implies in particular that it is not possible to decontaminate the preforms when they are held by a mandrel inserted in their neck.

[0016] However, irradiation of the face of the preform with ultraviolet radiation has less effectiveness on certain types of microorganisms such as molds than chemical decontamination obtained by a sterilizing agent such as hydrogen peroxide (H2O2).

[0017] Generally, in most known solutions, ultraviolet treatment is opposed to chemical treatment, the two treatments being mutually exclusive.

[0018] It has already been proposed to activate the sterilizing agent by means of ultraviolet radiation instead of infrared radiation.

[0019] To do this, the preforms are passed through a mist of hydrogen peroxide before being exposed to ultraviolet radiation. This provides superior decontamination than ultraviolet irradiation alone.

[0020] However, this method aims at the decontamination of preforms as a whole without specifically targeting the inner face of the neck, when the preforms pass into a feed device of a manufacturing installation.

[0021] Such a feed device has the function of straightening and aligning preforms which are delivered in bulk. After their alignment and straightening, the preforms are generally received in an accumulation line between guide rails, the preforms being free to slide and come into contact with each other. The movement of the preforms is then not controlled and the preforms are free to swing between the rails, in particular under the effect of the collision between preforms.

[0022] However, the internal face of the neck of the preform is not uniformly covered by the sterilizing agent, the hydrogen peroxide mist being deposited on said face in the form of multiple droplets between which, however, uncovered areas remain, in particular in the internal face of the neck which remains relatively inaccessible to passive exposure to the hydrogen peroxide mist.

[0023] Furthermore, in such a decontamination process, the mist tends to escape and settle on surrounding elements of the installation. However, since the sterilizing agent is extremely corrosive, it is necessary to dilute it strongly in order to avoid damaging the surrounding elements exposed to it too quickly. This further reduces the effectiveness of this decontamination method.

[0024] Furthermore, exposing the preforms to ultraviolet radiation in such a feeding device has many disadvantages. In fact, the duration of exposure of the preforms to ultraviolet radiation is not controlled and is not repeatable.

[0025] Furthermore, it is necessary to expose the preforms to ultraviolet radiation for a very long time which is not suitable for current production rates.

[0026] Indeed, in such a feeding device, variations in the speed of movement of the preforms are observed depending on the operating conditions of the downstream manufacturing installation. In the event of blockage or slowing down of the preforms, the latter may find themselves exposed for too long to ultraviolet radiation, which causes crystallization of the thermoplastic material, making them unsuitable for the formation of acceptable containers.

[0027] In addition, since the preforms are not held individually, some preforms may swing or be inclined when they pass under the ultraviolet radiation. As a result, an area of ​​the internal faces of the neck may be underexposed.

[0028] Generally speaking, there is a desire to continually increase the degree of decontamination, particularly for the packaging of agri-food products. Decontamination must also be compatible with very high production rates, for example up to at least 60,000 preforms per hour.

[0029] New solutions are therefore being sought to improve the degree of decontamination obtained as well as the types of micro-organisms destroyed during the decontamination operations. decontamination of an external face of a preform, in particular the internal face of the neck of the preform.

[0030] BRIEF SUMMARY OF THE INVENTION

[0031] The invention proposes a method for decontaminating an internal face of a neck of a preform made of thermoplastic material moving along a production path in a container manufacturing installation, each preform being held by an individual holding member, said decontamination method successively comprising at least:

[0032] - a treatment step consisting of exposing at least the internal face of the neck to a jet sterilizing agent comprising a sterilizing agent in a first treatment zone of the production path;

[0033] - a step of activating the sterilizing agent consisting of directly exposing the face internal part of the neck thus covered with sterilizing agent with ultraviolet radiation, in a second activation zone of the production path located downstream of the treatment zone.

[0034] According to another characteristic of the method carried out according to the teachings of the invention, during the activation step, the preforms move constantly along the production path.

[0035] According to another characteristic of the method carried out according to the teachings of the invention, during the treatment step, the preforms move constantly along the production path.

[0036] According to another characteristic of the method carried out according to the teachings of the invention, during the treatment step, the sterilizing jet is directed exclusively towards the interior of the preform to be treated.

[0037] According to another characteristic of the method carried out according to the teachings of the invention, the sterilizing jet is projected by a nozzle which moves jointly with the preform to be treated in the treatment zone.

[0038] According to another characteristic of the method carried out according to the teachings of the invention, the ultraviolet radiation is produced by at least one source which is arranged in a fixed manner relative to the production path.

[0039] The invention also proposes an installation for manufacturing containers from preforms made of thermoplastic material implementing the method according to the teachings of the invention, the installation comprising at least one device for conveying the preforms in a row along a production path, the conveying means comprising members for individually holding the preforms during their movement, the installation comprising:

[0040] - a preform processing area which is crossed by the production path and which comprises at least one nozzle for projecting a sterilizing jet comprising an agent sterilant intended to be directed directly towards the internal face of the neck of the preforms passing through the treatment zone;

[0041] - a sterilizing agent activation zone which comprises at least one source of ultraviolet radiation intended to be directed directly towards the internal face of the neck of the preforms passing through the activation zone, the activation zone being located downstream of the treatment zone.

[0042] According to another characteristic of the installation produced according to the teachings of the invention, the installation comprises a first conveying device in the treatment zone comprising associated holding members moving along a closed circuit, each holding member being associated with a nozzle for projecting said sterilizing jet moving jointly with the holding member along the closed circuit.

[0043] According to another characteristic of the installation produced according to the teachings of the invention, the installation comprises a second conveying device in the activation zone comprising associated holding members moving along a closed circuit, the at least one source of ultraviolet radiation being arranged in a fixed manner in the activation zone so that the holding members move in line with said sources.

[0044] According to another characteristic of the installation produced according to the teachings of the invention, the installation comprises a unit for thermal conditioning of the preforms, the activation zone being arranged upstream of the thermal conditioning unit.

[0045] According to another characteristic of the installation produced according to the teachings of the invention, the installation comprises a unit for thermal conditioning of the preforms, the activation zone being arranged downstream of the thermal conditioning unit.

[0046] According to another characteristic of the installation produced according to the teachings of the invention, the first conveying device is formed by a wheel on the periphery of which the holding members are arranged.

[0047] According to another characteristic of the installation produced according to the teachings of the invention, the second conveying device is formed by a wheel on the periphery of which the holding members are arranged.

[0048] According to another characteristic of the installation produced according to the teachings of the invention, the holding members are formed by notches. BRIEF DESCRIPTION OF THE FIGURES

[0049] Other characteristics and advantages of the invention will appear during the reading of the detailed description which follows for the understanding of which one refers will refer to the attached drawings briefly described below.

[0050] [Fig.l] is a top view which schematically represents a container manufacturing installation produced according to the teachings of the invention;

[0051] - [Fig.2] is a side view which represents a preform intended to be contaminated according to the method of the invention in the installation of [Fig.l];

[0052] - [Fig.3] is a top view which shows in detail a first zone of processing of the installation of [Fig.l];

[0053] - [Fig.4] is a sectional view along section plane 4-4 of [Fig.3] which re presents a preform undergoing a first processing step in the processing area of ​​the installation;

[0054] - [Fig.5] is a top view which shows in detail a second zone activation of the installation of [Fig.l];

[0055] - [Fig.6] is a sectional view along section plane 6-6 of [Fig.5] which re presents a preform undergoing a second activation step in the activation zone of the installation.

[0056] DETAILED DESCRIPTION OF THE FIGURES

[0057] In the remainder of the description, elements having an identical structure or similar functions will be designated by the same references.

[0058] In the remainder of the description, the terms "upstream" and "downstream" will be used with reference to the direction of movement of the preforms along their production path.

[0059] [Fig.l] schematically illustrates an installation 10 for the manufacture of containers 11 from preforms 12 made of thermoplastic material and more particularly of PET (polyethylene terephthalate).

[0060] As shown in [Fig.2], each preform 12 comprises a cylindrical body 14 with axis “X”. The body 14 comprises a lateral wall 16 which delimits an interior volume. The wall 16 has a shape of revolution around the axis “X”.

[0061] An upper end of the body 14 opens through a neck 18 having an opening 19 delimited radially by a rim 21. The neck 18 has the final shape of that of the container 11 to be obtained. As a result, the neck 18 must not undergo the slightest deformation during the manufacture of the container 11. The body 14 has a bottom 20 which closes its lower end and whose shape is generally hemispherical. The neck 18 has a collar 22 arranged at its junction with the body 14. The lower face of the collar 22 is intended to form a support face to allow the preform 12 to be supported during its molding and / or during its transport.

[0062] The neck 18 is delimited by an external face 24 and by an internal face 26. The internal face 26 has a cylindrical shape with axis "X".

[0063] At the end of their injection molding, the preforms 12 are cooled to give the thermoplastic material an amorphous state. It is thus possible to make the material thermoplastic that is malleable again upon heating beyond a glass transition temperature.

[0064] Referring again to [Fig.l], the manufacturing installation 10 comprises a thermal conditioning unit 30 and a forming unit 32.

[0065] The preforms 12 move in a row along a production path 34 which passes through the thermal conditioning unit 30 and the forming unit 32. The direction of movement of the preforms 12 is indicated by the arrows "F1" in [Fig.l]. During normal operation of the manufacturing installation 10, the preforms 12 are in constant movement along the production path 34.

[0066] The manufacturing installation 10 comprises means for conveying the preforms 12 in a row along the production path 34. The conveying means comprise members 58, 66 for individually holding the preforms 12 during their movement, which will be described in more detail later. Thus, the preforms 12 are constantly held individually throughout the production path 34.

[0067] The manufacturing installation 10 is generally supplied with preforms 12 by a device (not shown) for supplying straightened and aligned preforms in a row.

[0068] The production path 34 begins from the moment when the preforms 12, thus straightened and aligned in a row, are held individually by the individual holding members of the conveying means of the manufacturing installation 10. The start of the production path 34 is here indicated by the point PO.

[0069] The thermal conditioning unit 30 has the function of heating the body 14 of the preforms 12 to a temperature greater than or equal to the glass transition of the constituent material, for example greater than 70°C when this material is PET. The thermal conditioning unit 30 comprises a conveyor 36 (illustrated schematically) for transporting the preforms 12 by rotating them on themselves.

[0070] The conveyor 36 generally comprises mandrels (not shown) which are fitted axially in the neck 18 to transport the preforms 12. The mandrel blocks the opening 19 of the neck 18. Thus, the internal face 26 of the neck 18 is completely inaccessible when the preforms 12 circulate in the thermal conditioning unit 30. The mandrels move along a closed circuit. The mandrels are for example carried by the links of a chain or by independent shuttles moving along a rail.

[0071] The thermal conditioning unit 30 also comprises heating means 40 for heating the preforms 12. These are, for example, lamps facing reflectors or laser sources which emit heating electromagnetic radiation, here infrared radiation in the near infrared range.

[0072] The preforms 12 enter the thermal conditioning unit 30 when they are individually taken over by a mandrel of the conveyor 36, here at an entry point indicated by the point PI. The conveyor 36 transports them on a U-shaped section of their production path 34 passing through a heating zone 42. Their body 14 is heated as it passes by the heating means 40, which, where appropriate, are placed on one side or on either side of the preforms 12 relative to their direction of travel.

[0073] On the contrary, the neck 18 of the preforms 12 is maintained at a temperature much lower than the glass transition temperature. For this purpose, the necks 18 are protected from infrared radiation.

[0074] The hot preforms 12 are extracted from the thermal conditioning unit 30 after their passage through the heating zone 42 at an exit point P2. They are transferred into molds of the forming unit 32 by a transfer device 44, such as a transfer wheel, interposed between the thermal conditioning unit 30 and the forming unit 32.

[0075] The transfer wheel here comprises arms (not shown, as they are known per se) which successively grip the preforms 12, as they leave the thermal conditioning unit 30, at their neck 18, to introduce each of them in turn into a mold 46 of the forming unit 32. The forming unit 32 comprises a rotating carousel 48 at the periphery of which several blowing stations 50 comprising a mold 46 are arranged.

[0076] Each hot preform 12 leaving the thermal conditioning unit 30 is introduced into a mold 46 of the blowing station 50 to be blown there and transformed into a container 11 by deformation of its body 14. Once completed, the container 11 is extracted from the blowing station 50 by a second transfer device 52.

[0077] It is important that the inner face 26 of the neck 18 of the preforms 12 is sufficiently decontaminated before the preform 12 reaches the blowing unit 32.

[0078] To this end, the invention proposes a method for decontaminating the internal face 26 of the neck 18 which is particularly effective, even at very high production rates, greater than or equal to 66,000 containers per hour.

[0079] The decontamination process is applied to the preforms 12 as they travel along the production path 34. It is indeed important that each preform 12 is held by an individual holding member 58, 66 for the process to be effective.

[0080] The decontamination process successively comprises at least the following two steps.

[0081] A first treatment step "El" consists of exposing at least the internal face 26 of the neck 18 to a sterilizing jet 54 comprising a sterilizing agent in a first treatment zone 56 of the production path 34.

[0082] An example of carrying out this processing step "El" is notably illustrated in Figures 3 and 4.

[0083] The treatment zone 56 is here arranged upstream of the thermal conditioning unit 30.

[0084] The sterilizing agent is for example hydrogen peroxide (H2O2).

[0085] The sterilizing agent may be diluted in a diluent, such as water. This is, for example, a solution of sterilizing agent diluted to at least 10%, for example diluted to 20% or 25%.

[0086] The sterilizing jet 54 can be formed by mixing the vaporized solution with a pressurized gas, called "vector gas", to enable the propulsion of the sterilizing jet 54. The vector gas is for example formed by compressed air.

[0087] This first treatment step "El" is carried out by projecting at least one sterilizing jet 54 directed towards the inside of the preform 12 passing through the opening 19 while it is held by an individual holding member 58. The sterilizing jet 54 is more particularly projected directly towards the internal face 26 of the neck 18 of the preform 12.

[0088] The sterilizing jet 54 is shaped to allow the internal face 26 of the neck 18 to be completely and uniformly covered.

[0089] Each sterilizing jet 54 is emitted axially by a nozzle 60 arranged axially in line with the opening 19 of the preform 12, above the neck 18. This very advantageously makes it possible to deposit the sterilizing agent very precisely over the entire internal face 26 of the neck 18 of the preforms 12 in a uniform layer because the preforms 12 are held in position relative to the nozzle 60.

[0090] During the processing step "El", the preforms 12 constantly move in the processing zone 56.

[0091] Preferably, each nozzle 60 is mounted to move jointly with an associated holding member 58. In this way, the sterilizing jet 54 is projected by the nozzle 60 which moves jointly with the preform 12 to be treated in the treatment zone 56. Thus, during the treatment step "El", the sterilizing jet 54 is directed exclusively towards the interior of the preform 12 to be treated by passing through the opening 19.

[0092] Preferably, during the treatment step "El", the sterilizing jet 54 is directed exclusively towards the interior of the preform 12 to be treated.

[0093] As a result, it is possible to target exclusively the internal face 26 of the neck 18 of the preform 12 with the sterilizing jet 54 during its movement along the treatment zone 56. This makes it possible in particular to use only the quantity of sterilizing agent necessary for the treatment of the internal face 26 of the neck 18 without loss.

[0094] In a variant of the invention not shown, the treatment zone comprises a rail of nozzles which is stationary relative to the ground so that each preform passes successively under each nozzle of the rail during its movement along the treatment zone. treatment. In this variant, the external face of the cervix is ​​also exposed to the sterilizing jets.

[0095] The method comprises a second step "E2" of activating the sterilizing agent which occurs after the end of the first treatment step "El". This second activation step "E2" consists of directly exposing the internal face 26 of the neck 18 thus covered with sterilizing agent to ultraviolet (UV) radiation 61, in a second activation zone 62 located downstream of the treatment zone 56.

[0096] An example of carrying out this second activation step "E2" is illustrated in particular in figures 5 and 6.

[0097] The term "directly" means that the UV radiation 61 locally reaches the internal face 26 without passing through a wall of the preform 12. As explained in the preamble, the preforms 12 are in fact generally made of a material which does not allow UV radiation to pass easily.

[0098] The activation zone 62 is here arranged upstream of the thermal conditioning unit 30. Alternatively, it can be arranged downstream of the thermal conditioning unit 30.

[0099] This is, for example, UVc type 61 ultraviolet radiation, the wavelength of which extends between 100 nm and 280 nm. Preferably, the spectrum of the ultraviolet 61 radiation has an emission peak of the order of 254 nm.

[0100] The power of the ultraviolet radiation produced is for example of the order of 30 mW / cm2.

[0101] Ultraviolet radiation 61 is produced by a source such as an amalgam lamp or a light-emitting diode (LED).

[0102] During the activation step "E2", the preforms 12 move constantly along the production path.

[0103] The ultraviolet radiation 61 is here produced by at least one source 64 which is arranged in a fixed manner relative to the production path 34.

[0104] The preforms 12 are held individually by a holding member 66 during their passage through the activation zone 62. This makes it possible to promote total exposure of the internal face 26 of the neck 18, and this in a repeatable and controlled manner for all the preforms 12.

[0105] The activation zone 62 here comprises several sources 64 of ultraviolet radiation which are stationary relative to the ground so that each preform 12 passes successively under each source 64 during its movement along the activation zone 62, so that the UV radiation 61 penetrates into the preform 12 through its opening 19 before directly reaching the internal face 26 of the neck 18.

[0106] In a variant of the invention not shown, each source is mounted movably together with an associated holding member 66. Thus, the radiation ul Transviolet is produced by a source that moves together with the preform to be activated in the activation zone.

[0107] The fact that the preforms 12 are held by an individual holding member 66 during their passage through the activation zone 62 makes it possible to expose the entire internal face 26 of the necks 18 for a controlled duration.

[0108] By exposing the sterilizing agent that covers the inner face 26 of the neck 18 to UV radiation, the sterilizing agent is decomposed into even more oxidizing species, such as free radicals. The sterilizing agent is then said to have been "activated".

[0109] Such a method carried out according to the teachings of the invention makes it possible to obtain a very effective decontamination which makes it possible to divide by at least 100,000 the quantity of microorganisms present on the internal face 26 of the neck 18 just before the application of the decontamination method. In other words, the method according to the teachings of the invention makes it possible to obtain a logarithmic reduction of the contaminants present on the internal face 26 of the neck 18 of at least 5-log. This method is remarkable in that such a level of decontamination is obtained with an exposure of the internal face 26 of the necks 18 to ultraviolet radiation with a duration much less than one second, for example between 500 ms and 3 s. This makes the method particularly suitable for a very high container production rate, for example greater than or equal to 66,000 containers per hour.

[0110] To implement this method, the installation 10 for manufacturing containers 11 from preforms 12 made of thermoplastic material comprises means for conveying the preforms 12 in a row along the production path 34.

[0111] The installation 10 further comprises the zone 56 for treating the preforms 12 which is crossed by the production path 34 and which comprises at least one nozzle 60 for projecting a flow of sterilizing agent in the form of a sterilizing jet 54 comprising the sterilizing agent intended to be directed directly towards the internal face 26 of the neck 18 of the preforms 12 passing through the treatment zone 56.

[0112] The installation 10 also comprises the zone 62 for activating the sterilizing agent which comprises at least one source 64 of ultraviolet radiation 61 intended to be directed directly towards the internal face 26 of the neck 18 of the preforms 12 passing through the activation zone 62.

[0113] The activation zone 62 is located downstream of the treatment zone 56. The activation zone 62 is distinct from the treatment zone 56 so that the sterilizing agent is not exposed to ultraviolet radiation 61 before having been deposited on the internal face 26 of the neck 18 of the preforms 12.

[0114] The conveying means comprise members 58, 66 for individually holding preforms 12 during their movement. At least some of these conveying means comprise individual holding members 58, 66 which grip the preforms 12. from the outside. This allows the opening 19 to be left free and thus the internal face 26 of the necks 18 remains accessible from the outside to allow their successive exposure to the sterilizing jet 54 then to the ultraviolet radiation 61.

[0115] Thus, the previously described mandrels are not suitable because they are inserted into the necks 18 to grip the preforms 12 from the inside. This is the reason why the treatment and activation zones 56, 62 are arranged upstream or downstream of the thermal conditioning unit 30. Nevertheless, if the preforms were gripped in the thermal conditioning unit by holding members making it possible to make the internal face of their neck accessible, the treatment zone and the activation zone could be located in the thermal conditioning unit.

[0116] Such conveying means comprise a first conveying device 68 in the treatment zone 56. This first conveying device 68 comprises associated holding members 58 moving along a closed circuit.

[0117] Each holding member 58 is here associated with a nozzle 60 for projecting said sterilizing jet 54 moving jointly with the holding member 58 along the closed circuit. The nozzles 60 are controlled so as to project the sterilizing jet 54 when they are located in the treatment zone 56.

[0118] The sterilizing jet 54 is advantageously stopped outside the treatment zone 56. This makes it possible to avoid spreading the sterilizing agent outside the preforms 12. Thus, the sterilizing agent is advantageously saved. In addition, since the sterilizing agent is generally very corrosive, this makes it possible to avoid creating a corrosive atmosphere likely to damage certain elements of the installation 10.

[0119] The first conveying device 68 is formed by a wheel at the periphery of which the holding members 58 are arranged. This is for example a transfer wheel mounted to rotate relative to the ground around a vertical axis "Zl". The closed circuit thus has a circular shape.

[0120] In a variant of the invention not shown, the holding members are carried by independent shuttles moving along a rail.

[0121] The holding members 58 are for example formed by notches on the periphery of which the lower face of the collar 22 is pressed, as illustrated in [Fig.4].

[0122] In a variant not shown, the holding members can be formed by clamps which grip the preforms from the outside, below and / or above the collar.

[0123] This first conveying device 68 is here arranged upstream of the thermal conditioning unit 30 and the entry point PO into the installation 10.

[0124] In the embodiment shown in the figures, the means for conveying the preforms 12 in the activation zone 62 comprise a second conveying device 70 comprising associated holding members 66 moving along a closed circuit. The second conveying device 70 is distinct from the first conveying device 68.

[0125] In a variant of the invention not shown, the holding members are carried by independent shuttles moving along a rail.

[0126] In a variant of the invention not shown, the activation zone and the treatment zone are arranged on the same conveying device.

[0127] The second conveying device 70 is formed by a wheel at the periphery of which the holding members 66 are arranged. This is for example a transfer wheel mounted to rotate relative to the ground around a vertical axis "Z2". The closed circuit thus has a circular shape.

[0128] The holding members 66 are for example formed by notches on the periphery of which the lower face of the collar 22 is pressed.

[0129] In a variant not shown, the holding members can be formed by clamps which grip the preforms from the outside, below and / or above the collar.

[0130] This second conveying device 70 is here arranged upstream of the thermal conditioning unit 30 and downstream of the first conveying device 68.

[0131] In a variant of the invention not shown, the second conveying device is arranged downstream of the thermal conditioning unit. Preferably, the second conveying device is arranged upstream of the forming unit.

[0132] In the embodiment shown in Figures 5 and 6, the activation zone 62 comprises sources 64 of ultraviolet radiation which are fixed relative to the ground. Thus, the holding members 66 of the second conveying device 70 move past said sources 64 when they are in the activation zone 62. In this way, the preforms 12 move past, neck 18 directed towards said sources 64 when they pass axially past the latter. Thus, the UV radiation 61 penetrates axially inside the preforms 12 through the opening 19.

[0133] The sources 64 are for example amalgam lamps which are associated with reflectors 72 which make it possible to direct the ultraviolet rays 61 directly towards the internal face 26 of the neck 18 of the preforms by entering through the opening 19.

[0134] The invention is here applied specifically to the decontamination of the internal face of the cervix. The internal face of the body can however benefit in the same way as the internal face of the cervix, in particular if a part of the sterilizing jet also exposes the internal face of the body and the ultraviolet radiation reaches the entire internal face of the body.

[0135] The decontamination method carried out according to the teachings of the invention thus makes it possible to obtain very effective decontamination of the preforms despite very high production rates. The method also makes it possible to protect the integrity of the neck 18 of the preforms 12 by not exposing them to infrared radiation.

[0136] Very advantageously, the fact that the preforms are held individually during each step of the process makes it possible to very precisely control the time of exposure to the sterilizing jet and the time of exposure to ultraviolet radiation of the internal face of the body. The quantity of sterilizing agent applied to each preform and the radiation dose for each preform are thus very precisely controlled.

Claims

Claims

1. Method for decontaminating an internal face (26) of a neck (18) of a preform (12) made of thermoplastic material moving along a production path (34) in an installation (10) for manufacturing containers (11), each preform (12) being held by an individual holding member (58, 66), said decontamination method successively comprising at least: - a treatment step (El) consisting of exposing at least the internal face (26) of the neck (18) to a sterilizing jet (54) comprising a sterilizing agent in a first treatment zone (56) of the production path (34); - a step (E2) of activating the sterilizing agent consisting of directly exposing the internal face (26) of the neck (18) thus covered with sterilizing agent to ultraviolet radiation (61), in a second zone (62) of activation of the production path (34) located downstream of the treatment zone (56).

2. Method according to the preceding claim, characterized in that during the activation step (E2), the preforms (12) move constantly along the production path (34).

3. Method according to any one of the preceding claims, characterized in that during the processing step (El), the preforms (12) move constantly along the production path (34).

4. Method according to any one of the preceding claims, characterized in that during the treatment step (El), the sterilizing jet (54) is directed exclusively towards the interior of the preform (12) to be treated.

5. Method according to the preceding claim, characterized in that the sterilizing jet (54) is projected by a nozzle (60) which moves together with the preform (12) to be treated in the treatment zone (56).

6. Method according to any one of the preceding claims, characterized in that the ultraviolet radiation (61) is produced by at least one source (64) which is arranged fixedly relative to the production path (34).

7. Installation (10) for manufacturing containers (11) from preforms (12) made of thermoplastic material implementing the method according to any one of the preceding claims, the installation (10) comprising at least one device (68, 70) for conveying the preforms (12) in a row along a production path (34), the conveying means comprising members (58, 66) for individually holding the preforms (12) during their movement, the installation (10) comprising: - a zone (56) for treating the preforms (12) which is crossed by the production path (34) and which comprises at least one nozzle (60) for projecting a sterilizing jet (54) comprising a sterilizing agent intended to be directed directly towards the internal face (26) of the neck (18) of the preforms (12) passing through the treatment zone (56); - a zone (62) for activating the sterilizing agent which comprises at least one source (64) of ultraviolet radiation intended to be directed directly towards the internal face (26) of the neck (18) of the preforms (12) passing through the activation zone (62), the activation zone (62) being located downstream of the treatment zone (56).

8. Installation (10) according to the preceding claim, characterized in that it comprises a first conveying device (68) in the treatment zone (56) comprising associated holding members (58) moving along a closed circuit, each holding member (58) being associated with a nozzle (60) for projecting said sterilizing jet (54) moving jointly with the holding member (58) along the closed circuit.

9. Installation (10) according to any one of claims 7 or 8, characterized in that it comprises a second conveying device (70) in the activation zone (62) comprising associated holding members (66) moving along a closed circuit, the at least one source (64) of ultraviolet radiation being arranged in a fixed manner in the activation zone (62) so that the holding members (66) move in line with said sources (64).

10. Installation (10) according to any one of claims 7 to 9, characterized in that it comprises a unit (30) for thermal conditioning of the preforms (12), the activation zone (62) being arranged upstream of the thermal conditioning unit (30).

11. Installation (10) according to any one of claims 7 to 9, characterized in that it comprises a unit (30) for thermal conditioning of the preforms (12), the activation zone (62) being arranged downstream of the thermal conditioning unit (30).

12. Installation (10) according to claim 8, characterized in that the first conveying device (68) is formed by a wheel at the pe- rim of which the holding organs (58) are arranged.

13. Installation (10) according to claim 9, characterized in that the second conveying device (70) is formed by a wheel on the periphery of which the holding members (66) are arranged.

14. Installation according to any one of claims 12 or 13, characterized in that the holding members (58, 66) are formed by notches.

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