METHOD AND DEVICE FOR STERILIZING, BY IRRITATION, A CONTAINER MADE OF THERMOPLASTIC MATERIAL

Description

TECHNICAL FIELD OF THE INVENTION

[0001] The invention relates to a method and device for sterilizing a thermoplastic container by irradiation.

[0002] The invention relates more particularly to a device according to claim 1.

[0003] The invention also relates to a sterilization method according to claim 7. STATE OF THE ART

[0004] We know from the state of the art various sterilization processes for sterilizing at least the inside of a preform and / or a container made of thermoplastic material.

[0005] The manufacture of a thermoplastic container is obtained from a hot preform, generally pre-conditioned thermally in an oven of a container manufacturing facility before being introduced into a mold to be transformed by blowing with at least one fluid under pressure, with or without stretching.

[0006] Various types of containers are manufactured (bottles, flasks, jars, etc.) which are intended, in particular but not exclusively, for use in packaging products in the food industry.

[0007] In the field of manufacturing containers for the food industry, every effort is made to reduce the risk of microbiological contamination of containers by pathogens, i.e., microorganisms.

[0008] This is why the Applicant has already proposed to implement various actions to eliminate pathogens, such as germs (bacteria, molds, etc.), which are likely to affect the product contained in such containers.

[0009] In particular, we can distinguish on the one hand actions aimed at destroying microorganisms to sterilize at least the inside of the container and, on the other hand, actions aimed more generally at preventing the contamination of containers by such microorganisms.

[0010] The prior art documents FR-2.915.127, WO-03 / 084818 and EP-2.094.312, to which reference will be made for further details, are cited as non-limiting examples of such actions.

[0011] Document FR-2.915.127 describes a container manufacturing installation comprising a protective enclosure delimiting an area within which is arranged a blow molding machine of the container type which is fed by means of transfer into preforms previously thermally conditioned in a furnace.

[0012] According to the teachings of this document, the installation includes a filtered air blowing system inside the enclosure to establish, in particular, overpressure in order to limit the risks of contamination of both the preforms coming out of the oven and the manufactured containers.

[0013] Document WO-03 / 084818 describes, for example, a decontamination treatment by irradiation of the neck of preforms with ultraviolet (UV) radiation, before the introduction of the preforms into the oven.

[0014] Document EP-2.094.312 describes, for example, an irradiation treatment with ultraviolet (UV) radiation implemented in a particular way in a furnace to decontaminate at least the external surface of the preform during heat conditioning.

[0015] Document WO-2006 / 136498 on behalf of the Applicant describes, for example, a decontamination treatment of a preform consisting of depositing by condensation a substantially uniform film of mist of a sterilizing agent on the inner wall of the preform.

[0016] Such a decontamination treatment by condensation, known as "chemical decontamination," gives satisfactory results since decontamination levels of up to 6Log are obtained.

[0017] It is worth noting that the quantity of microorganisms can be counted after, in particular, washing, filtration and culturing operations.

[0018] This determines a logarithmic reduction in the number of microorganisms, for example, said to be of the order of 3Log (or 3D), equivalent to 1000 units (10 3< ).

[0019] However, alternative solutions to chemical decontamination are being sought that do not use sterilizing agents, such as hydrogen peroxide (H2O2), but without sacrificing the decontamination result.

[0020] In document WO-2016 / 120544, the Applicant proposed an alternative solution consisting of sterilizing a thermoplastic container using a pulsed electron beam and a moving reflector.

[0021] For the industrial application of such a treatment process for sterilizing containers, in addition to technical expertise, one of the main challenges today is primarily economic, due to the high cost of the emitter used to generate the electron beam. Other documents dealing with container sterilization using electron beams are JP H11 248896 A, JP 2002 000705 A, and US 2018 / 015191 A1.

[0022] This is why we are looking for solutions to optimize the use of an emitter, reduce the total number of emitters, and achieve the same sterilization results for the containers.

[0023] However, it is necessary to have a sufficient duration of irradiation during the treatment to irradiate the surfaces of the container to be sterilized with a quantity of electrons that allows a lethal dose to be obtained for microorganisms, that is to say a dose greater than or equal to 10 kGy (kilo-Gray).

[0024] The treatment process must also be compatible with current container production rates which, for example, in the case of PET bottles, reach more than 60,000 bottles per hour.

[0025] The aim of the invention is in particular to propose a new sterilization device which will solve at least some of the drawbacks of the prior art and in particular to optimize the use of one emitter for each type of container and to reduce the number of emitter(s). BRIEF SUMMARY OF THE INVENTION

[0026] To this end, the invention proposes a sterilization device of the type described above, characterized in that said at least one emitter is configured to be able to tilt the head at an angle of inclination which, between the main axis of the emitter and the axis of the container, is determined as a function of the height of the container in order to optimize the dose of irradiation received by said container.

[0027] According to the invention, the container is irradiated by an electron beam with a dose that is greater than or equal to that of the prior art when said container has a height less than that of the emitter head, i.e. a lethal dose for microorganisms.

[0028] Advantageously, the said lethal dose is likely to be obtained with a sterilization device having fewer emitter(s) due to the increase in the duration of irradiation, maximizing the dose of irradiation received.

[0029] Advantageously, the invention makes it possible to reduce the number of emitters needed by increasing the irradiation time of the containers, optimizing the radiation dose delivered by the emitter head for a container of a given height, and this without ultimately reducing the rate, i.e., the average speed of circulation of the containers.

[0030] Advantageously, the implementation of a treatment process according to the invention is compatible with the production rates of containers and therefore capable of receiving an industrial application by integrating such a sterilization device into a container manufacturing installation, such as PET bottles.

[0031] Advantageously, the container is sterilized by irradiating an empty container before filling it.

[0032] Preferably, container irradiation is implemented in a container manufacturing facility between the molding (or blow molding) unit and the next unit, such as a filling or labeling unit.

[0033] Depending on the application, labeling of containers may indeed be carried out before or after they are filled.

[0034] Compared with a chemical preform decontamination process according to the aforementioned WO-2006 / 136498 document, the invention makes it possible to greatly simplify the design of a container manufacturing plant from a preform, in particular the molding unit (or blow molder).

[0035] Sterilizing the final container (and not the preform) eliminates many of the methods previously used in such a container manufacturing facility, as the microorganisms present are destroyed when the container is irradiated by means of an electron beam, preferably of the pulsed type.

[0036] Thus, it is no longer necessary to implement specific means (such as insufflation systems, etc.) to preserve the sterility of a preform after its chemical treatment, i.e. during its thermal conditioning, its transformation by blowing or stretch-blowing into a container, and this up to the filling and closing of the container.

[0037] Advantageously, sterilization by irradiation according to the invention makes it possible to sterilize both the inside and outside of a container simultaneously.

[0038] Thus, devices for treating preforms by irradiation using UV radiation are likely to be eliminated.

[0039] Air supply and, more generally, air filtration systems that contribute to achieving a clean manufacturing environment are also likely to be eliminated.

[0040] Advantageously, the elimination of all such devices and / or systems allows for significant savings on the cost of a manufacturing facility, both in terms of acquisition and operation.

[0041] Advantageously, since the irradiation step is carried out downstream of the molding unit (or blow molder) in a manufacturing facility, the actions carried out upstream of the molding unit, in particular for the destruction of microorganisms and the prevention of contamination risks of containers, can be eliminated in whole or in part.

[0042] Advantageously, the design of the molding unit (or blow molder) is significantly simplified, and its manufacturing and operating costs are reduced. Indeed, the so-called "CIP" (Clean-in-Place) cleaning operations can be eliminated.

[0043] Therefore, it is no longer necessary to use expensive materials for the molding unit, such as stainless steel, chosen for their resistance to chemical attack, particularly corrosion, resulting from the cleaning products used during such "CIP" operations.

[0044] Advantageously, it will be appreciated that the invention goes against the teachings of the state of the art which, in order to preserve the pace, consists of multiplying the number of emitters along the path until a dose of irradiation sufficient to sterilize each container is reached. According to other features of the invention :

[0045] The angle of inclination of the head is determined so that the ratio of the height of the container to the height of the emitter is close to 1; the angle of inclination of the head is between a minimum value greater than 0° and a maximum value of 90°; the head of the emitter is mounted to rotate freely in order to tilt the head according to said angle of inclination; the inclination of the head is controlled by actuation means; the head is mounted to translate freely in order to vary the distance between the head and said at least one container to be irradiated; the head is telescopic relative to the emitter; the emitter is mounted to translate freely relative to said at least one container to be irradiated.

[0046] The invention further proposes a sterilization method of the type described above, characterized in that, the direction of movement followed by the flow of containers transported by a conveyor system being orthogonal to the main axis of the containers, said treatment method comprises at least: an irradiation step of said at least container from the outside by an electron beam emitted by the head of said emitter arranged to present an angle of inclination which, between the principal axis of the emitter and the axis of the container, is equal to a value determined according to the height of the container.

[0047] Advantageously, said treatment process includes at least one preliminary adjustment step consisting, when the direction of movement followed by the flow of containers is orthogonal to the main axis of the containers, of adjusting the inclination of the head of said emitter according to an angle of inclination of a determined value so that the ratio of the height of the container to the height of the emitter is close to 1.

[0048] Advantageously, the said flow of containers being transported by the conveying system along a given path, with a determined spacing, called initial pitch, corresponding to the distance between the axes of two consecutive containers, the processing process includes at least one step of controlling the conveying system to selectively vary said initial pitch between two consecutive containers in order to reduce, at least in an irradiation zone of the path in which said emitter including the head is arranged, the spacing between the containers of said flow to a proximal pitch which is less than said initial pitch. BRIEF DESCRIPTION OF THE FIGURES

[0049] Other features and advantages of the invention will become apparent upon reading the detailed description that follows, for an understanding of which reference should be made to the attached drawings in which: there figure 1is a top view that schematically represents thermoplastic containers, for example here bottles, forming a flow and which are transported at a constant pace by a conveyor system along a path along which emitters of a sterilization device are arranged to irradiate said containers from the outside with an electron beam and which illustrates the implementation of a treatment for the sterilization by irradiation of containers according to the prior art; the figure 2 is a side view representing the head of one of the emitters of the sterilization device according to the state of the art of the figure 1 which is arranged on a section of the path to form a sterilization zone by irradiation of the containers and opposite which are two consecutive containers of the flow and which illustrates said head whose axis A is coaxial with the axis O of the containers; the figure 3is a side view which, analogous to the figure 2 , represents an emitter comprising a head which is inclined according to the teachings of the invention at an angle of inclination determined according to the dimensions of the container, in particular the height, and which illustrates such an inclination of the emitter head with respect to the axis of the container at an angle of inclination determined to optimize the irradiation of said container of a given height, respectively for two containers of different dimensions. DETAILED DESCRIPTION OF THE FIGURES

[0050] In the following description, we will adopt, without limitation, the longitudinal, vertical and transverse orientations with reference to the trihedron (L, V, T) represented in the figures.

[0051] By convention, the longitudinal and transverse orientations which together define a horizontal plane are determined in a fixed manner with respect to the containers.

[0052] The terms "upstream" and "downstream" will be used without limitation in reference to the direction of movement of the containers which are transported by the conveying system from upstream to downstream along a given route.

[0053] The terms "upper" and "lower" or "top" and "bottom" will also be used, without limitation, with reference to the vertical orientation. The terms "inside" or "outside" and "internal" or "external" are used in particular with respect to containers, the internal volume being delimited by the wall of the container, the body of which has a neck and is closed by a base, such that said wall delimits the inside and the outside respectively.

[0054] In the description that follows, elements designated by the same reference numbers denote analogous, similar or identical means.

[0055] We illustrated, on the Figures 1 And 2, a sterilization device 100 for the implementation of a treatment process for the sterilization by irradiation of containers 10 according to the prior art for the Applicant.

[0056] In this application, the thermoplastic containers 10 to be sterilized are preferably bottles, in particular made of PET (Polyethylene Terephthalate), manufactured from a preform. Alternatively, the thermoplastic container 10 is a jerrycan, a bottle, a jar, etc.

[0057] As illustrated on the figure 1 , the container 10 comprises a body 12 equipped with a neck 14 and closed by a bottom 16, said neck 14 circumferentially delimiting an opening.

[0058] The container 10 has an internal surface 20 delimited by a wall 22 forming the body 12, the neck 14 and the bottom 16, as well as an external surface 24.

[0059] Preferably, the neck 14 of the container 10 has at least one collar 26 which extends radially outwards and has a lower face 28.

[0060] Container 10 has a principal axis O.

[0061] As illustrated on the Figures 1 And 2 , the axis O of the container 10 extends vertically here according to the trihedron (L, V, T).

[0062] Preferably, the containers 10 are transported in a so-called "neck up" position during their irradiation in the process by at least one electron beam (F) delivered by the sterilization device 100.

[0063] The sterilization device 100 is for example integrated into a container manufacturing installation (not shown) in which the sterilization of containers 10 is thus carried out by irradiation.

[0064] Such a container manufacturing installation, particularly for PET bottles, is well known from the state of the art.

[0065] The manufacture of a thermoplastic container is obtained from a hot preform, generally previously thermally conditioned in a thermal conditioning unit or oven before being introduced into one of the molds of a molding unit (or blow molding machine) to be transformed by blowing using at least one fluid under pressure, with or without stretching.

[0066] The sterilization of the containers is therefore carried out downstream of the blowing unit or blower (not shown) of such a container manufacturing installation.

[0067] In such an installation, the 10 containers (and preforms) made of thermoplastic material are successively transported in the form of a continuous flow (fx) by a conveyor system 200 through the different units of the installation ensuring the manufacturing steps.

[0068] Such a 200 conveying system also includes transfer wheels, many examples of which are known.

[0069] For the record, we mainly distinguish between transfer wheels comprising a notched plate associated with guiding means and transfer wheels comprising clamps, controlled or not at least in opening.

[0070] There figure 1 represents a section of the path followed by the containers 10 coming from the molding unit, an arrow at each end of the section indicating the direction of flow (fx) of containers 10, from upstream to downstream.

[0071] On the section of the route of the figure 1 , the containers 10 of the flow (fx) are transported successively by transfer wheels which, here numbering five, are respectively referenced 201 to 205.

[0072] The containers 10 are transported with a determined spacing, called P, corresponding to the distance between the axes O of two consecutive containers 10 of the flow (fx).

[0073] On the section of the path associated with the sterilization device 100, the step P between two containers 10 is constant, that is to say that the step P does not vary between the first transfer wheel 201 located upstream and the last transfer wheel 205 located downstream.

[0074] According to an important characteristic, besides the step P between two consecutive containers 10, the speed of movement of the containers 10 forming said flow (fx) is also constant.

[0075] The speed of movement of the containers 10 determines the production rate of such a manufacturing installation, expressed in number of containers per hour, said rate being determined in particular according to the filling unit.

[0076] The sterilization device 100 includes emitters, here five emitters referenced successively 101 to 105, which are each intended to irradiate said containers 10 from the outside with an electron beam F.

[0077] Transmitters 101 to 105 are arranged along the path followed by the flow (fx) of containers 10, one transmitter being associated, for example, with each of the transfer wheels 201 to 205.

[0078] For the implementation of a treatment process according to the state of the art, the sterilization device 100 includes a significant number of emitters necessary to obtain a dose of irradiation finally received by each container 10 which allows to guarantee its sterilization.

[0079] The emitters 101 to 105 are arranged on the side of the path followed by the flow (fx) of containers 10 so that the containers 10 are successively irradiated radially from the outside by each beam (F) of electrons emitted by one of the emitters.

[0080] Each container 10 receives a given dose of irradiation each time, which is determined in particular by the duration of exposure to the electron beam (F), and therefore by the speed of movement of the containers 10 in front of the emitters 101 to 105.

[0081] On the figure 1, a container 10 of the flux (fx) is successively irradiated by each of the five emitters 101 to 105 of the sterilization device 100 and ultimately receives a cumulative amount of irradiation corresponding to a lethal dose for which the sterilization of its internal surface 20 and its external surface 24 of the container 10 is obtained.

[0082] However, the cost of an emitter remains particularly high, which remains a hindrance to the sterilization of containers by irradiation.

[0083] This is one of the reasons why we are looking for solutions to optimize the use of such emitters, with the aim of reducing the total number of emitters used, but without reducing production rates.

[0084] The emitters 101 to 105 forming said sterilization device 100 are identical so that the description of emitter 101 given below also applies to the other emitters of the sterilization device 100.

[0085] As illustrated on the figure 2 , the emitter 101 has a main axis A which extends vertically according to the trihedron (L, V, T).

[0086] The emitter 101 comprises an irradiation head 111 having a parallelepiped shape and extending, along its main axis A, over a height "H" and orthogonally to said axis A over a width "l".

[0087] An emitter 101 is thus capable of irradiating from the outside, via said fixed head 111, a container 10 having an external diameter D and vertically a height h, from its bottom 16 to its neck 14, said height h of the container 10 being less than or equal to the height H of the head 111 of the emitter 101.

[0088] However, while the height H of the head 111 of the emitter 101 is fixed, determined by construction, the format of the containers 10 varies according to the applications.

[0089] Indeed, the same manufacturing facility is capable of manufacturing containers 10, such as bottles, ranging for example from a capacity of half a liter (or less) up to a capacity of two liters.

[0090] Part of the electron beam (F) emitted by the head 111 of the emitter 101 is therefore lost when no part of the container 10 is radially opposite to be irradiated.

[0091] The lost part of the electron beam (F) emitted by an emitter is in particular a function of the difference between the height H of the head 111 and the height h of the container 10.

[0092] This also represents an additional cost, particularly with regard to the electrical energy consumed to power the emitter producing the electron beam (F).

[0093] An emitter 101 has a head 111 having a height H determined by construction, while the height h of the manufactured containers 10 varies according to the applications.

[0094] Thus, when the container 10 has a height h which is equal to half the height H of the emitter head, half of the electron beam (F) emitted by the emitter head is then lost since this part of the beam (F) will not irradiate any container.

[0095] We will describe below, by comparison with the state of the art illustrated by the Figures 1 And 2 , a device 100 for sterilizing by irradiation at least one container 10 made of thermoplastic material.

[0096] As described previously, the thermoplastic container 10 is of the type having a main axis O and comprising a body 12 having a neck 14 and closed by a bottom 16.

[0097] The sterilization device 100 includes at least one emitter 120 which, equipped with a head 125, is made according to the invention.

[0098] Like emitters 101 to 105, emitter 120 has a head 125 which extends along a principal axis A and is intended to emit and delimit a beam (F) of electrons to radially irradiate at least one container 10 from the outside.

[0099] According to the invention, said at least one emitter 120 is configured to be able to rotate the head around a beam propagation axis and thus tilt the head 125 at an angle (α) of inclination of the principal axis A of the emitter with respect to the axis O of the container. Said angle (α) is determined as a function of the height (h) of the container 10.

[0100] Advantageously, the value of the angle (α) of inclination is determined to optimize, maximize, the dose of irradiation received by a container 10 when said container 10 is irradiated by the electron beam (F) emitted by the head 125 is that the container is moved by the conveyor system 200.

[0101] Preferably, the angle (α) of inclination of the head 125 is determined so that the ratio of the height (h) of the container 10 to the height (H) of the head 125 of the emitter is close to 1 to limit the electron losses of said beam (F).

[0102] The angle (α) of inclination of the head 125 is an acute angle, located "inside" the intersection of the axes A and O.

[0103] The angle (α) of inclination of the head 125 is between a minimum value greater than 0°, the axis A of the head 125 not being coaxial with the axis O of the container 10, and a maximum value of 90° corresponding to a horizontal arrangement of the head 125.

[0104] By comparison, as illustrated in the figure 2 , the head 111 of the transmitter 101 according to the prior art is arranged so that the main axis A of the transmitter extends vertically, coaxially with the axis O of the container 10.

[0105] Advantageously, the head 125 of the transmitter 120 is mounted to rotate movably in order to selectively tilt the head 125 according to a given value of said angle (α) of tilt.

[0106] Preferably, the tilt of the head 125 is controlled by actuation means (not shown).

[0107] Advantageously, the head 125 is mounted to move in translation to vary the distance between the head 125 and said at least one container 10 to be irradiated, in particular as a function of the external diameter D of the container 10.

[0108] Preferably, the 125 head is mounted telescopically relative to the 120 transmitter.

[0109] In an alternative not shown, the emitter 120 is mounted mobile in translation relative to at least one container 10 to be irradiated, for example by means of a rail system allowing the emitter 120 and therefore the head 125 to slide relative to the container 10.

[0110] Compared to the prior art, the inclination of the head 125 allows for an increase in the dose of electrons received by the container 10.

[0111] Advantageously, such an increase is likely to allow a reduction in the number of emitter(s) used in a sterilization device 100 equipping a container manufacturing facility 10 thanks to an exploitation of the electron beam (F) emitted by the emitter head.

[0112] To illustrate the principle of the invention, we have represented on the figure 3 two containers 10 of different dimensions, a first container 10 having a height h1 and a second container 10 having a height h2, greater than the height h1 of the first container.

[0113] To optimize the irradiation of a container 10 and limit the losses of electrons emitted by an emitter 120, the head 125 of the emitter 120 is inclined relative to the container 10 at said angle (α) of inclination determined as a function of the height h of the container 10.

[0114] The inclination angle (α) corresponds to the angle formed by the intersection of the principal axis A of the emitter 120 and the axis O of the container 10, the direction of movement followed by the container 10 being orthogonal to the principal axis O of the container 10, as illustrated by an arrow on the figure 3 .

[0115] According to the two examples illustrated on the figure 3 , the emitter 120 is inclined at an angle (α1) of inclination between its main axis A and the axis O of the container 10 of height (h1) or inclined at an angle (α2) of inclination between its main axis A and the axis O of the container 10 of height (h2).

[0116] Preferably, the head 125 of the emitter 120 is inclined so that the two ends extend respectively beyond the neck 14 and the bottom 16 of the container 10, said ends of the emitter 120 having been shown on the figure 3 by rectangles in dashed lines.

[0117] Advantageously, the neck 14 and the bottom 16 of the container 10 are thus optimally irradiated by the electron beam (F) emitted by the part of the head 125 of the emitter 120 located radially opposite and not partially by a portion of it.

[0118] As illustrated on the figure 3 , the container 10 travels between the ends of the head 125 of the emitter 120 a distance L1 or L2 being irradiated successively from the bottom 16 towards the neck 14 (following the direction of movement of the flux (fx) from right to left as indicated by the arrow).

[0119] Advantageously, the container 10 is simultaneously rotated about itself, around its axis O, during its irradiation by the electron beam (F) emitted by the emitter 120.

[0120] Preferably, the rotational speed of the container 10 is determined so that the entire circumference of the container 10 is irradiated at least once.

[0121] Advantageously, each container 10 is thus irradiated homogeneously by the electron beam (F) (commonly called "e-beam" in English).

[0122] Preferably, the irradiation to sterilize the containers 10 from the outside is obtained by means of a pulsed electron beam (F), that is to say an electron beam which is formed by a succession of pulses.

[0123] Advantageously, the pulses forming said pulsed electron beam (F) have an emission duration, intensity and energy which are determined according to the applications.

[0124] For example, one can refer to the teachings of the aforementioned document WO-2016 / 120544 on the physical characteristics of such a pulsed electron beam (F).

[0125] Advantageously, an emitter 120 comprising a tiltable head 125 according to the invention, is capable of replacing at least one of the emitters 101 to 105 of a sterilization device 100.

[0126] Preferably, several transmitters 120 are arranged along the path followed by the flow (fx) of containers 10 transported by the conveyor system 200.

[0127] For each type of container 10, the sterilization device 100 can then be optimized by tilting the head of each emitter to maximize the use of the emitted electron beam (F).

[0128] Advantageously, the total number of emitters required to achieve the irradiation dose of a given container 10 is likely to be reduced since electron losses are completely eliminated compared with the prior art described with reference to Figures 1 And 2 .

[0129] Thus, it is possible, for example, to use a smaller number of emitter(s), for example three emitters instead of five previously, without the radiation dose received by the container 10 being affected, thus preserving the degree of sterilization finally obtained.

[0130] Advantageously, reducing the number of emitter(s) in a sterilization device 100 makes it possible to substantially reduce the costs of implementing sterilization by irradiation using an electron beam (F).

[0131] Indeed, for a sterilization result that is at least equivalent, reducing the number of emitters first of all reduces the cost of acquiring a sterilization device, particularly one intended to equip a container manufacturing facility.

[0132] Advantageously, reducing the number of emitter(s) also reduces the operating costs of a sterilization device, in particular the electrical energy consumption required to produce an electron beam (F).

[0133] The sterilization device 100 comprises several emitters 120, for example three, which are arranged along the path followed by the flow (fx) of containers 10 transported by the conveying system 200 as illustrated in the figure 1 .

[0134] A displacement plane is defined by the direction of the principal axis (O) of the containers and by the direction of displacement followed by the flow (fx) of containers 10.

[0135] An irradiation plane is defined by the direction of beam propagation and by the direction of the principal axis (A) of the head.

[0136] Advantageously, the displacement plane and the irradiation plane are perpendicular to each other.

[0137] In a first advantageous embodiment, the direction of propagation is perpendicular to the plane of displacement, the angle (α) serves to optimize the irradiation during the movement of the container.

[0138] In a second advantageous embodiment, the propagation direction is not perpendicular to the plane of movement. The height of the container is taken into account to position the head so as to irradiate the bottom of the container and thus optimize irradiation.

[0139] The invention further proposes a method of sterilizing by irradiation of such a flux (fx) of containers 10 made of thermoplastic material of the type having as before a main axis (O) and comprising a body 12 having a neck 14 and closed by a bottom 16 by a sterilization device 100 comprising at least one emitter 120 having a head 125 which, having a main axis (A), is intended to emit a beam (F) of electrons.

[0140] As before, the direction of movement followed by the flow (fx) of containers 10 transported by the conveyor system 200 is orthogonal to the main axis (O) of the containers 10.

[0141] According to the invention, said treatment process comprises at least one step of irradiating said at least container 10 from the outside by an electron beam (F) emitted by the head 125 of said emitter 120 arranged to have an angle (α) of inclination which, between the main axis (A) of the emitter and the axis (O) of the container, is equal to a value determined as a function of the height (h) of the container 10.

[0142] Advantageously, the treatment process includes at least one preliminary adjustment step consisting, when the direction of movement followed by the flow (fx) of containers 10 is orthogonal to the main axis (O) of the containers 10, of adjusting the inclination of the head 125 of said emitter 120 according to an angle (α) of inclination of a determined value so that the ratio of the height (h) of the container 10 to the height (H) of the head 125 of the emitter 120 is close to 1.

[0143] To further increase the radiation dose received by each container 10 of the flux (fx), the spacing between two consecutive containers 10 greater than the width "l" of the emitter 101 illustrated on the figure 2 is advantageously reduced so that a container 10 is always opposite the electron beam (F).

[0144] As explained with reference to the figure 1 , the flow (fx) of containers 10 is transported by the conveyor system 200 along a given path, with a determined spacing, called initial step (P), corresponding to the distance between the axes (O) of two consecutive containers (10).

[0145] Advantageously, the treatment process includes at least one step of controlling the conveying system to selectively vary said initial pitch (P) between two consecutive containers 10 in order to reduce, at least in an irradiation zone of the path in which said at least emitter 120 comprising the head 125 is arranged, the spacing between the containers 10 of said flow (fx) to a proximal pitch (P') which is less than said initial pitch (P).

[0146] Advantageously, the modification of said initial step (P) to obtain the proximal step (P') between the containers 10 of said flow (fx) is obtained by varying the speed of movement of the containers 10 transported in the vicinity of said irradiation zone.

[0147] The variation of the pitch is obtained for example by mechanical means of the cam and roller type or preferably by electrical means, such as motors, associated with each container 10 transported.

[0148] The control step of the conveying system includes an initial step of modifying the pitch (P) which includes at least one phase of deceleration of the containers 10 in order to obtain said proximal pitch (P').

[0149] The proximal pitch (P') corresponds to a minimum spacing for which the juxtaposed containers 10 are able to be driven in rotation on themselves without interference, without contact.

[0150] Advantageously, the reduction of the step (P) is obtained by reducing the speed of the containers passing opposite the head of the emitter, thereby increasing the exposure time to the electron beam (F), and ultimately increasing the radiation dose received by the container 10, which corresponds to a lethal dose.

[0151] Preferably, the velocity of the containers 10 is reduced but remains above zero. Alternatively, the velocity of the containers 10 could, however, be temporarily zero, by stopping when the container is irradiated by the emitter.

[0152] Advantageously, the control step of the conveying system includes a final step of modifying the pitch comprising at least one acceleration phase to vary the spacing of the containers 10 again in order to restore, after irradiation, said initial pitch (P) between the containers 10 of the flow (fx).

Claims

1. Device (100) for sterilizing by irradiation at least one container (10) made of thermoplastic material of the type having a main axis (O) and comprising a body (12) provided with a neck (14) and closed by a bottom (16), said device (100) comprising: - a conveying system having a direction of displacement of the container and capable of transporting the container of which the main axis (O) is orthogonal to the direction of displacement, - at least one emitter (120) provided with a head (125) capable of emitting a beam (F) of electrons to irradiate from the outside said at least one container (10) in a direction of propagation of the beam, the head (125) having a main axis A orthogonal to the direction of propagation of the beam, characterized in that said at least one emitter (120) comprises an irradiation head (125) having a parallelepipedal form and extending, along its main axis A, over a height "H" and orthogonally to said axis A over a width "l" so as to emit and to delimit a beam (F) of electrons to radially irradiate at least one container (10) from the outside, and in that said emitter (120) is configured to be able to tilt the head (125) according to a tilt angle (α) which lies between the main axis (A) of the head of the emitter and the axis (O) of the container and which is determined as a function of the height (h) of the container in order to optimize the irradiation dose received by said container (10).

2. Device according to Claim 1, characterized in that the head (125) delimits a cross section of the beam (F) and has a height (H) corresponding to the greatest dimension of the cross section, the device has a projected height (H1) equal to the projection of the height of the head on a direction orthogonal to the direction of displacement, the tilt angle (α) of the head (125) is determined such that a ratio of a height (h) of the container to the projected height (H1) of the emitter is close to 1.

3. Device according to Claim 1 or 2, characterized in that the tilt angle (α) of the head (125) lies between a minimum value greater than 0° and a maximum value of 90°.

4. Device according to any one of Claims 1 to 3, characterized in that the head (125) of the emitter (120) is mounted so as to be able to move in rotation in order to tilt the head (125) according to said tilt angle (α).

5. Device according to Claim 4, characterized in that the tilt of the head (125) is controlled by actuation means.

6. Device according to any one of the preceding claims, characterized in that the head (125) is mounted so as to be able to move in translation to vary the distance between the head (125) and said at least one container (10) to be irradiated.

7. Method for sterilizing by irradiation a flow (fx) of containers (10) made of thermoplastic material of the type having a main axis (O) and comprising a body (12) provided with a neck (14) and closed by a bottom (16) by a sterilization device (100) comprising at least one emitter (120) provided with a head (125) which, having a main axis (A), is intended to emit a beam (F) of electrons, the method comprising: - a step of irradiation of said at least one container (10) from the outside by the beam (F) of electrons emitted by the head (125) of said emitter (120), which is arranged to have a tilt angle (α) which, lying between the main axis (A) of the head of the emitter and the axis (O) of the container, is equal to a value determined as a function of the height (h) of the container along the main axis (O) of the container, said irradiation head (125) having a parallelepipedal form and extending, along its main axis A, over a height "H" and orthogonally to said axis A over a width "l" so as to emit and to delimit a beam (F) of electrons to radially irradiate at least one container (10) from the outside.

8. Treatment method according to Claim 7, characterized in that said treatment method comprises at least: - a step of transporting the flow of containers along a direction of displacement, - calculating a projected height (h1) of the container on a direction orthogonal to the direction of displacement, - the head (125) delimits a cross section of the beam (F) having a height (H) corresponding to the greatest dimension of the cross section, calculating a projected height (H1) equal to the projection of the height (H) of the head on the direction orthogonal to the direction of displacement, - a setting step preliminary to the irradiation step, consisting in setting the tilt of the head (125) of said emitter (120) according to a tilt angle (α) of a value that is determined so that a ratio of the projected height (h1) of the container to the projected height (H1) of the head of the emitter is close to 1.