FR3082749A1 - METHOD OF DECONTAMINATION USING ELECTRON BEAMS OF A BOTTOM CONTAINER IN THERMOPLASTIC MATERIAL - Google Patents

Abstract

The invention relates to a method for obtaining a container (1) of decontaminated plastic material, having a peripheral seating area (10) surrounding a central area in the general shape of an arch (4) whose concavity is directed towards the outside of the container. According to the invention, an electronic bombardment operation using an electronic bombardment source (2) is carried out on a portion (27A) of the wall (5) of an intermediate container (32) provided with a vault (34) having a concavity directed towards the interior of the container, and in that the applied energy is such that the electrons can penetrate the thickness of the portion (27A) of wall (9) closest to the source (2) and strike a portion (27B) of the opposite wall in order to decontaminate it.

Description

Decontamination process using electron beams from a container with a re-entrant bottom made of thermoplastic material.

FIELD OF THE INVENTION

The object of the invention is to obtain sterile containers, such as bottles, which are obtained by blowing or stretch-blowing preforms of thermoplastic material (for example P.E.T.). It applies to obtaining sterile containers during their manufacture or in the event of re-use.

PRIOR ART

As a preliminary remark, it is indicated that in the rest of this description and in the claims, for the sake of simplification, unless otherwise indicated, when the terms top, bottom, vertical, horizontal, above, below, upper, lower and any comparable term will be used, they will be interpreted by considering that the container is upright, that is to say carried on a horizontal plane by its seat. The direction or the longitudinal axis of the container is a direction or an axis, crossing the bottom container, from the bottom of the container to its opening (drinking or neck) thereof.

The manufacture of a container of thermoplastic material is obtained from a hot preform, generally previously conditioned thermally in an oven of an installation for the manufacture of containers before being introduced into a mold to be transformed there by blowing by means at least one pressurized fluid, with or without drawing.

Various types of containers are thus manufactured (bottles, flasks, pots, etc.) forming hollow bodies which are in particular, but not exclusively, intended to be used for packaging products in the food industry.

In the field of the manufacture of containers for the food industry, efforts are being made to reduce the risk of microbiological contamination of the containers by pathogenic agents, namely micro-organisms.

This is the reason why, the Applicant has already proposed to implement various actions to eliminate pathogenic agents, such as germs (bacteria, molds, etc.), which are capable of affecting the product contained in such containers.

Various methods are known for obtaining sterile containers. Thus, it has been envisaged in the past to sterilize the containers after their manufacture by filling them with a sterilizing product. This method was applicable during the manufacturing process, for example by implementing it after removing the containers from their manufacturing mold and before a subsequent filling operation; it was still applicable with a view to reusing the containers, after they have been returned to a cleaning unit for re-use. However, this method consumes a lot of sterilizing product, even if it could be envisaged to recycle at least a part of it, and it was long to implement, because the filling had to be followed by a contact time and action of the product, then emptying of the container followed by drying (or even rinsing then drying). Such a sequence of operations, in particular at the end of manufacturing, was not compatible with the very high rates of manufacturing machines.

We then imagined faster processes, compatible with the production rates of the containers. Thus, the process described and claimed in American patent US 6562281 B1 in the name of Sidel S.A., former name of the present applicant, allows the containers leaving their blow molding (or stretch blow molding) molds to be sterile. For this purpose, a sterilizing product is injected into the container preforms, then the product is activated using the heat prevailing in the preform heating oven and the containers are then blown.

Excellent results in terms of asepsis are obtained with this process, known as “chemical”, since it allows degrees of decontamination of the order of 6Log to be obtained.

However, this process is not applicable for the decontamination of containers intended to be reused, since it is implemented during manufacture and requires a prior step in the presence of the preforms.

Furthermore, although it requires less sterilizing product than the previous solutions, it nevertheless goes against the alternative solutions currently being investigated making it possible not to use a sterilizing agent, such as hydrogen peroxide ( H2O2), and this either in order to be respectful of the environment, without sacrificing the result obtained for decontamination, or in order to avoid obtaining too much residual sterilizing product, which is a legal constraint.

In order to remedy the drawbacks of the various methods previously mentioned, it was then envisaged to carry out a sterilization treatment of containers already manufactured by applying to them the energy of electron beams (the scientific term commonly used for a beam or beams). (x) of electrons is the acronym E-beam (s)).

One such method consists in applying the energy of one or more electron beams (with radiation characteristics chosen taking into account the plastic material constituting the containers) on the outer wall of the containers to be sterilized.

The application is carried out on the outer wall due to technical constraints: the containers made of thermoplastic material, such as PET (Polyethylene Terephthalate), which are discussed here are in particular but not exclusively bottles. However, such hollow container are delimited as a whole by a wall and have a neck radially delimiting an opening and extending by a body closed axially by a bottom. For the decontamination of the interior of this type of container made of thermoplastic material, one of the problems encountered remains the limited accessibility to the interior surface of the container offered by the opening of the neck which generally has a reduced diameter.

The arrangement of an emitter of the electron beam outside the container makes it possible to overcome this problem of limited accessibility, the electrons of the beam emitted by the emitter pass through, from the outside to the inside. , radially the wall of the body and the neck of said container to irradiate the interior of the container to be sterilized.

Energy can be applied by scanning, in the case of a beam, or of several superimposed beams, on the external wall of the containers to be treated. The application can be in pulsed or continuous form, while the containers are in relative rotation relative to the beams. The electrons penetrate the wall and sterilize the interior wall of the containers. The superimposition of beams is a priori easier to control than scanning and, above all, it allows greater processing speed.

However, when the electron beam of the continuous type (in English “continuous e-beam”) used is emitted by a so-called “high energy” emitter, that is to say generally with an energy greater than 500 KeV and for example of the order of MeV, it is then observed that the electrons of such a continuous beam cause modifications to the thermoplastic material with which said electrons interact by passing through the wall of the container.

However, such modifications alter the properties of the thermoplastic material of the container and are likely to compromise its subsequent use as packaging.

In order to limit the interactions between the continuous electron beam and the thermoplastic material, the use of lower energy emitters, in particular low energy emitters (less than 500 KeV) has been envisaged.

However, the lower energy level of the electrons in the continuous beam results in insufficient decontamination from the moment when the beam must pass through several thicknesses through the container. This is the case at the bottom of the container when the latter is not provided with a flat bottom, but is provided with a bottom having a peripheral seating area and a central area in the general shape of a vault whose the concavity is directed towards the outside of the container, as, for example, with containers having a bottom called champagne bottom such as those described in the patents granted under the numbers US 6,634,317 B2 and US 6,769,561 B2 or, more generally with the containers the bottom of which, without being a champagne bottom, has a peripheral seating area surrounding an arched inward central area with a concavity directed towards the outside (cf. for example international application WO 2016/207213 A1, in the name of the present Applicant ).

With this type of container, the desired degree of decontamination at the bottom location can be obtained by increasing the irradiation time to compensate for the low penetration of the low-energy continuous electron beam, but the times required for treatment of a container are then incompatible with the production rates.

In addition, problems of interactions between the continuous electron beam and the thermoplastic material remain and the deterioration of the thermoplastic material is all the more important as the duration of irradiation is long.

A possible solution for sterilizing containers having a bottom of the aforementioned type is described in international application WO 2016/120544 in the name of the Applicant. It consists in using a device using an external transmitter and a reflector, in the form of a rod inserted axially in the container. Electrons emitted from the outside are reflected by the reflector at all points of the internal wall. This solution is however complicated to put into practice. The reflector must be adapted as a function of the shape (in particular of the reliefs) of the containers and its positioning in the container requires a complex kinematic chain.

Another solution for the decontamination of containers such as bottles is described in US Pat. No. 7,145,155 B2, which describes a process using superimposed electronic beams emitted from the outside. According to this method, a longitudinal mapping of the container is carried out, prior to a phase of decontamination of a set of containers of the same type, highlighting the thinner zones (zones where only two portions of walls are opposite -vis) and thicker areas (typically those where there are several wall portions facing each other, at the bottom). During decontamination, primary electrons are injected through the outer wall with insufficient energy to penetrate the entire container at the location of the thicker zones, but sufficient to pass through a wall and reach the opposite wall. -vis, and the energy of secondary electrons completes that of the primary electrons at the location of the thicker zones, so as to penetrate the entire thickness. The process is described as causing a phenomenon of scattering of the primary electrons in the thicker zones thanks to the secondary electrons.

However, this process requires an implementation in a controlled gaseous medium (it can be a vacuum in the container), because it is this which allows this scattering of primary electrons. It is therefore complex to implement: in addition to the need to carry it out in a gaseous medium and therefore to generate the appropriate medium, two types of electron sources must be considered.

SUMMARY OF THE INVENTION

A first object of the invention is to provide a reliable and simple process which allows easy decontamination of a container, which in the position of use, is provided with a bottom having a peripheral seating area surrounding a central area. in the general shape of a vault whose concavity is directed towards the outside of the container.

According to the invention, a method for obtaining a container made of decontaminated plastic, the container comprising in configuration of use:

- a body consisting of a peripheral wall closed on itself around a longitudinal axis,

- a bottom, which is crossed by the longitudinal axis, is disposed at a first end of the body and has a peripheral seating area surrounding a central area in the general shape of a vault whose concavity is directed towards the outside of the container,

- an opening arranged, relative to the body, opposite the bottom, near a second end of the body, the method comprises:

an operation of exposing the container facing a source of electronic bombardment, the wall of the container being turned towards this source;

- an electronic bombardment operation of the wall of the container, during its exposure in front of the source;

and is characterized in that the bombardment is carried out on an intermediate container provided with a vault having a concavity directed towards the interior of the container, and in that the applied energy is such that the electrons can penetrate the wall portion the closer to the source and strike an opposite portion of the wall in order to decontaminate it.

Thus, owing to the fact that the bombardment is carried out while the vault has a concavity directed towards the interior of the container, no zone of the container, seen from the outside, has more than two portions of wall facing each other and it is therefore not necessary to modulate or compensate for the energy which should be applied to take account of any variations in thickness. The bombardment configuration is therefore easier.

According to other characteristics, taken alone or in combination:

- during electronic bombardment, the intermediate container is rotated about the longitudinal axis;

- The intermediate container is obtained during a step of manufacturing a container, which consists in forming the body and the opening of a final container and a bottom having a peripheral zone constituting a primer of the seat zone of the final container and a vault shaped so as to have a concavity directed towards the interior of the container;

- The intermediate container is obtained by first producing a container with a bottom provided with a zone constituting the initiation of the seating area of a final container and a vault shaped so as to have a concavity directed towards the outside of the container, then by causing the curvature of the vault to be inverted so that the concavity initially directed towards the outside of the container is directed towards the inside;

- after decontamination, the vault is inverted in order to position it with its concavity directed towards the outside of the container;

- the inversion of the vault in order to position it with its concavity directed towards the outside of the container is carried out before filling the container;

- the inversion of the vault in order to position it with its concavity directed towards the outside of the container is carried out after filling the container;

- the inversion of the vault in order to position it with its concavity directed towards the outside of the container is carried out after filling and capping of the container.

Thus, the invention is applicable to any container which has a bottom with a peripheral seating area surrounding a central area in the general shape of a vault whose concavity is directed towards the outside of the container, and makes it possible to obtain decontaminated containers. at the end of their manufacture or to decontaminate and allow the reuse of containers that have already been used.

INTRODUCTION OF FIGURES

Other characteristics and advantages of the invention will appear on reading the following description made in connection with the appended drawings, in which:

FIG. 1 is a schematic view making it possible to apprehend what is happening in terms of electron transmissions with a method of the prior art. This view comprises a medallion with an enlarged detail of the bottom zone of a container treated according to this prior art.

FIG.2 is a schematic view illustrating the interaction between a lower part of the container having its bottom and a bombardment source according to the method of the invention.

FIG.3 schematically illustrates an arrangement for returning the container to the position of use.

FIG.4 schematically illustrates a direct embodiment of an intermediate container.

FIG. 5 schematically illustrates a pre-step for forming an intermediate container

DETAILED DESCRIPTION

In FIG. 1 is shown schematically a container 1 facing a source 2 of electronic bombardment, in a configuration according to which the bottom 3 of the container 1 has a peripheral seating area 10 surrounding a central area in the general shape of a vault 4, which arch 4 has a concavity directed towards the outside.

In the example illustrated, the container 1 is a bottle which, in addition to its bottom 3, comprises a body 5 extended by a shoulder 6 itself surmounted by a neck 7 having an opening 8 - also called a drink -, which makes it possible to fill or empty the container.

The body 5 of the illustrated container consists of a wall 9 closed on itself and limited, below, by the bottom 3 and above, in the direction of the opening 8 by the shoulder 6.

The wall 9 can be cylindrical, as in the example, and in this case the container has a longitudinal axis X-X, of vertical orientation when the container is placed on its bottom. Instead of being cylindrical, the wall may have a different, even variable and / or hybrid section along its height (polygonal, such as square with rounded corners, or even triangular, ovoid, rectangular, provided with grooves, etc. .). However, even when the wall is not really cylindrical, it is considered that the container has a vertical axis.

In FIG. 1, the container 1 is in the configuration of use, that is to say that in which an end user takes possession of it. The concavity of the vault 4 of the container, which is surrounded by a peripheral seating area 10 intended to hold the container 1 in the upright position during storage on a support surface (not shown), is directed outwards, so as to be opposite said bearing surface.

Such a container 1 is generally obtained by heating and then drawing / blowing a preform of thermoplastic material (such as polyethylene terephthalate - PET -) in a forming mold.

This technology, also called bi-orientation, is well known to those skilled in the art, without it being necessary to detail it further. Reference may be made, for example, to patent US4355968A in the name of the company Pont à Mousson SA, from which the present applicant is based, and which is one of the first patents on bi-orientation equipment.

When it comes to decontaminating the interior and exterior of the container 1, the latter is positioned opposite the source 2. This is arranged to emit a plurality of superimposed beams 20, 21, ... 25, 26 ( continuous or pulsed) in the direction of axis XX. During the emission, the container is rotated around its axis, as illustrated by the arrow surrounding the axis, so that during rotation, the entire periphery of the container 1 is at least once facing a beam.

The energy of each beam is such that it allows it to pass through the thickness of the portion 27 of the wall closest to the source 2 and strike the portion 28 of the wall opposite, without however to cross.

It can therefore be seen that the beams, such as those illustrated by the references 20 to 25 in FIG. 1, which emit in the direction of the body 5 manage to pass through the part 27 of the wall closest to the source 2 and strike the part 28 of diametrically opposite wall. Thus, during the rotation of the container 1 on itself, all of the walls, exterior and interior, of the neck 7 and of the body 5 undergo the same bombardment and are decontaminated in the same way.

On the other hand, the beams, such as those illustrated by the reference 26 in FIG. 1, which emit in the direction of the bottom 3 manage to pass through the portion 29 of the bottom wall closest to the source 2 and strike the portion 30 of the vault 4 which is on their path. They are therefore stopped by the presence of the arch 4 and, consequently, they fail to bombard the portion 31 of the bottom wall farthest from the source 2, and this all the more so since the bottom zones are very thick, which adds to the difficulty of the passage of electrons. It is understood that during a complete rotation of the container 1 on itself, the parts 29, 30 of the bottom wall which are opposite the arch 4, as well as the arch 4 itself undergo bombardment substantially twice less important than the parts 27, 28 of the wall of the body 5 and of the neck 5, insofar as the energy emitted by the beams from the source 2 is the same from one to the other.

FIGS. 2 and 3 illustrate the way in which the method of the invention is implemented on an intermediate container.

According to the invention, as illustrated in FIG.2, the method is applied not to a container 1 in configuration of use, that is to say comprising a bottom 3 with a seating area 10 surrounding a central zone in the general shape of a vault 4 having a concavity oriented towards the outside of the container, but on an intermediate container 32, comprising a bottom 33 with a vault 34 inverted with respect to the configuration of use of the final container. In other words, the arch 34 of the intermediate container 32 has a concavity oriented towards the interior of the container 32. The arch is surrounded by a peripheral zone 35, which constitutes the initiation of the seat zone 10 of the container final in its configuration of use (see FIG.1).

Apart from this difference in the structure of the bottom, the rest of the intermediate container 32 is in every way comparable to the container 1 of FIG. 1, that is to say that it comprises a body 5, which is oriented according to a longitudinal axis XX and is extended by a shoulder 6, itself surmounted by a neck 7 having an opening 8, which makes it possible to fill or empty the container. Thus, the elements of the intermediate container 32 which are found on the final container, that is to say the container 1 of FIG.1 bear the same references.

In order to carry out the decontamination, the intermediate container 32 is placed opposite a source 2 of electronic bombardment, making it possible to generate beams 200, 210, 220, 230, 240, 250, 260 of superimposed electrons. The application of the electrons can be in pulsed or continuous form, while the intermediate container 32 is in rotation around its axis X-X, as shown diagrammatically by the arrow surrounding this axis X-X. At this stage, it should be noted that the source 2 can be identical to that used in the prior art (FIG. 1), insofar as the difference with the process of the invention lies in the shape of the container treated and not in the source.

It is easy to see that each of the beams, including those 260 directed towards the bottom 33 of the intermediate container 32 meet each time only two portions 27A, 27B of walls opposite with respect to the axis (the portion 27A close to the source and the opposite portion 27B), that is to say the two wall portions of the body 5, the two wall portions of the neck, and finally two portions of the wall limiting the vault 34. Consequently, during rotation of the intermediate container 32 on itself, all of the walls, external and internal, of the neck 7, of the body 5 and of the vault 34 undergo the same bombardment and are decontaminated in the same way.

It is easily understood that, if the intermediate container 32 is not perfectly cylindrical in revolution, but can be considered as oriented around a longitudinal axis, the same phenomena occur there.

Following the bombardment operation, the intermediate container 32 is subjected to an operation of inverting the vault 34, so that the latter arrives in the retracted configuration (that is to say with a concavity directed towards the outside. of the container), which makes it possible to obtain a final container, similar to that illustrated in FIG. 1. For this, as illustrated briefly in FIG. 3, the intermediate container 32 is positioned in a tool having a member 36, such as a finger, making it possible to push back the arch 34 and bring it to its final shape. In this FIG. 3, the member 36 is illustrated in a position where the arch 34 is partially pushed back and begins to present a concavity directed towards the outside of the container. The arch 34 is therefore in an intermediate position between that which it occupies in FIG. 2 and that of a final container (such as the container illustrated in FIG. 1).

The intermediate container 32 which is exposed to the bombardment source 2 can be obtained in various ways.

According to a first implementation, illustrated schematically in FIG. 4, the intermediate container 32 is directly obtained, by implementing a blowing or stretch-blowing process of a preform thermally conditioned at the softening temperature of its constituent plastic, in a forming mold arranged to obtain an intermediate container 32 whose bottom 33 comprises a vault 34 with a concavity facing the interior of the container.

To this end, the mold firstly comprises a bottom 37 of the mold provided with a hollow imprint 38 making it possible to obtain said bottom 33 having a zone 35 constituting the initiation of the zone 10 for the seat of a container. 1 definitive and a vault 34 shaped so as to have a concavity directed towards the interior of the intermediate container 32.

Then, according to this first implementation, in addition to the bottom 37 of the mold, the mold comprises, in a manner known per se, two half molds 39A, 39B (partially visible in FIG. 4) which make it possible to form the rest of the container, namely its body 5 and the shoulder 6 which surmounts the body, and there is provided a rod 40 for stretching the preform (the latter not being shown).

Following the molding of the intermediate container 32, it is extracted from the mold and then positioned opposite the source 2 using appropriate means allowing it to be rotated on itself during the bombardment (cf. FIG2) .

After bombardment, the intermediate container 32 is subjected to the operation of inverting the vault 34, as described above in connection with FIG. 3.

However, it has been observed during tests that, in certain cases, the first implementation described above may not give full satisfaction, in the sense that it is sometimes difficult to reverse the arch 34 after decontamination, since the constituent material is hardened.

This is why, in a second implementation, the intermediate container 32 is obtained by first producing by blowing or stretch-blowing a container 41 with a bottom provided with a zone 35 constituting the initiation of the zone 10 seat of a final container 1 and a vault 42 shaped so as to have a concavity directed towards the outside of the container 41 (cf. FIG.5). In other words, the shape of the container 41 corresponds substantially to that of a final container. Following this, the arch 42 is pushed back from the inside to the outside, for example using a pusher 43 introduced into the container through its opening 8 (cf. the opening 8 in FIG. 1), so that at the end of this step, the intermediate container 32 such as that visible in FIG. 2 is obtained.

The fact that the vault underwent a first inversion makes easier the final inversion after the bombardment.

Obtaining a container 41 with a bottom provided with a zone 35 constituting the initiation of the seating zone 10 of a definitive container 1 and a vault 42 shaped so as to present a concavity directed towards the outside of the intermediate container 41 can be obtained by a simple blow molding or stretch blow molding in a mold whose imprint corresponds to that of this container 41.

Alternatively, it can use a so-called boxing process, that is to say a process in which the mold base is movable vertically relative to the half-molds and one begins by carrying out a bottom over-stretching towards the inside the

WO 2010/058098 in the name of (cf., for example, the advantage of boxing initial repelling the preform, then the container obtained by the Applicant is repelled), lies in the fact that the slight over-stretching and the bottom make it easier the two successive inversion stages, namely that which makes it possible to pass from a vault 42 shaped so as to present a concavity directed towards the outside to the vault to a shaped so as to present a concavity directed towards the inside and one that allows outward (final container).

to return to a directed concavity

In a stake position that is to say fill the

In an inversion of the vault in order to work, its concavity directed towards the outside of the container, to obtain the final container is carried out before container.

with a variant, this inversion is carried out after filling the container.

In a variant, this inversion filling and capping of the container.

other is performed after

Claims (8)

1. Method for obtaining a container (1) made of decontaminated plastic, the container comprising in configuration of use: - a body (4) constituted by a peripheral wall closed on itself around a longitudinal axis (X-X), - A bottom (3) which is crossed by the longitudinal axis (XX), is disposed at a first end of the body and has a peripheral seating area (10) surrounding a central area in the general shape of a vault (4), the concavity is directed towards the outside of the container, - an opening (8) arranged, relative to the body, opposite the bottom (3), near a second end of the body, the method comprising: - an operation of exposing the container to a source (2) of electronic bombardment, a portion (27A) of the wall (9) of the container being turned towards this source; - an electronic bombardment operation of said portion (27A) of the container, during its exposure in front of the source (2); characterized in that the bombardment is carried out on an intermediate container (32) provided with a vault (34) having a concavity directed towards the interior of the container (32), and in that the energy applied is such that the electrons can penetrate the thickness of said portion (27A) of wall (9) closest to the source (2) and strike a portion (27B) of opposite wall in order to decontaminate it. 2. Method according to claim 1, characterized in that, the intermediate container (32) is rotated about the longitudinal axis (X-X) during the electronic bombardment. 3. Method according to one of claims 1 or 2, characterized in that the intermediate container (32) is obtained during a manufacturing step, which consists in forming the body (5) and the opening (8) d '' a final container and a bottom (33) having a peripheral zone (35) constituting a primer of the seating zone (10) of the final container and a vault (34) shaped so as to have a concavity directed inwards of the container. 4. Method according to one of claims 1 or 2, characterized in that the container (32) intermediate is obtained by first making a container (41) with a bottom provided with a zone (35) constituting the initiation of the seating area (10) of a container (1) final and a vault (42) shaped so as to have a concavity directed towards the outside of the container (41) then causing an inversion of the curvature the vault (42) so as to obtain a vault (34) with a concavity directed towards the interior of the container. 5. Method according to one of claims 1 to 4, characterized in that, after decontamination, the vault (34) is inverted in order to position it with its concavity directed towards the outside of the intermediate container (32) and to obtain the final container (1). 6. Method according to one of claims 1 to 5, characterized in that the inversion of the vault (34) in order to position it with its concavity directed towards the outside of the container (32) is carried out before filling the container . 7. Method according to one of claims 1 to 5, characterized in that the inversion of the vault (34) in order to position it with its concavity directed towards the outside of the container is carried out after filling the container (32). 8. Method according to one of claims 1 to 5, characterized in that the inversion of the vault in order to position it with its concavity directed towards the outside of the container is carried out after filling and capping the container (32).