WO2010013262A1

WO2010013262A1 - Apparatus for sterilising container closures

Info

Publication number: WO2010013262A1
Application number: PCT/IT2008/000510
Authority: WO
Inventors: Pietro Ferraguti; Paolo Pagliarini
Original assignee: Gea Procomac S.P.A.
Priority date: 2008-07-29
Filing date: 2008-07-29
Publication date: 2010-02-04

Abstract

An apparatus (1) for sterilising container closures (T), defined by a lateral wall (3) suitable for engaging the mouth of a container and an upper wall (4) suitable for closing said mouth, comprising guide means (6) for feeding the closures (2) to a sterilisation station, and a first and a second emitter (5) of ionising radiation oriented in prefixed directions of irradiation and positioned on opposite sides of the guide means (6) so as to intercept the closures (2) with said radiation in the sterilisation station; the guide means (6) are configured so that, when the closures (2) are passing inside the sterilisation station, the upper wall (4) thereof is inclined in relation to said directions of irradiation.

Description

APPARATUS FOR STERILISING CONTAINER CLOSURES

TECHNICAL FIELD AND BACKGROUND ART.

The object of the present invention is an apparatus for sterilising container closures.

Therefore, the present invention relates to the technical sector of container treatment, especially for the bottling industry.

In particular, the invention relates to an apparatus for sterilising container closures defined by a lateral wall suitable for engaging a container mouth and an upper wall suitable for closing said mouth.

Said closures thus define a concave portion suitable for receiving the container mouth, which may be screwed onto or inserted into it.

For example, such closures may consist in caps made of polymeric materials such as

PET or HDPE.

As is generally known, in the food industry, and in particular in the sector of aseptic filling of containers with beverages and in the sector of aseptic food packaging, there exists a need to sterilise the containers and the closures thereof both internally and externally before they are filled.

Sterilisation is generally achieved using chemical agents, e.g. hydrogen peroxide or peracetic acid, which can be used on surfaces of every type, such as paper, plastic, metal or organic materials.

To ensure that filling takes place in aseptic conditions it is necessary to sterilise not only the containers but also their closures, for example caps or stoppers, which serve to seal the containers at the end of the filling process.

According to the known art, the sterilisation of closures, be they caps or stoppers, takes place by means of sources of ionising radiation, for example radioactive gamma or beta ray sources, or by means of chemical agents.

The present invention refers in particular to sterilisation apparatus that use ionising radiation.

Ionising radiation is radiation comprised of particles with high kinetic energy able to remove electrons from atoms, thereby achieving two important effects:

- each interaction between a particle and an atom generates an ion (radical), with consequent freeing of an electron;

- the freed electrons are in turn capable of generating additional ions. With particular reference to sterilisation by means of ionising radiation sources, the use of electron beam emitters, commonly referred to as "electron cannons", is generally known.

The electron beams are focused on the object to be sterilised in such a manner that the electrons can act directly on pathogenic agents, e.g. viruses, funguses or bacteria, in order to damage the DNA thereof and deactivate the protein and enzymes necessary to their survival.

Sterilisation by ionising radiation has the important advantage of reducing the operating costs of filling/bottling plants, since it reduces the consumption of chemical agents, water and sterilising substances. Furthermore, the use of ionising radiation sources permits the construction of environmentally sustainable plants, as it solves the problem of chemical residue disposal and reduces the production of toxic waste.

With particular reference to the sterilisation of caps and stoppers, apparatus equipped with a magazine for containing the closures, connected to a chute for feeding the closures themselves to a sterilisation station, where they are submitted to ionising radiation of the type described above, are generally known within the bottling industry.

In particular, in the known solutions the closures are conveyed in a longitudinal direction along a vertical plane by means of a chute that constitutes guide means, so that the closures are disposed with the upper wall in a vertical position; the emitters of ionising radiation are facing each other on opposite sides of the chute so as to define between them a volume submitted to irradiation. Therefore, the sterilisation station is defined within such volume situated between the emitters.

In this manner, when the closures pass inside the sterilisation station they receive ionising radiation perpendicularly to their path of travel, from both sides. That is to say, from one side the closures receive ionising radiation on the outer surface of the upper and lateral walls and from the other side they receive ionising radiation on the concave portion consisting of the inner surface of the lateral wall and the inner surface of the upper wall.

It should be observed that achieving the sterilisation of products using exposure to ionising radiation depends on the reaching of a given dose, i.e. a given quantity of energy absorbed by the product to be sterilised.

The ionising radiation used in these applications comprises accelerated electrons with an energy of 150-200 keV, not sufficient to penetrate more than about 200 μm into the materials generally employed in the manufacture of closures (polymeric materials such as PET, HDPE); consequently, only the surfaces directly exposed to the electron beam are actually sterilised.

In this connection, it should be observed that the known sterilisation apparatus do not guarantee a complete and reliable sterilisation.

The closures in fact have numerous shadow surfaces due to the presence of threads and gaskets and in general because of their geometrical configuration. In particular, the concave portion of the closures receives a dose that is often insufficient to ensure the complete and correct sterilisation thereof.

In this respect it should be observed that the intensity of irradiation may be increased, in principle, by bringing the emitters (and hence the closures disposed in the sterilisation station) closer together, or by increasing the power of the emitters themselves. However, the emitters cannot be spaced closer than a minimum distance apart (nor can their power be increased beyond a maximum value), as this would damage the electron emission windows the emitters themselves are equipped with.

DISCLOSURE OF THE INVENTION.

The object of the present invention is to overcome the aforesaid limitations and to provide an apparatus for sterilising container closures by ionising radiation which allows the entire surface of the closures, and particularly the concave portion thereof, to be sterilised in a complete and effective manner.

Another object of the present invention is to enable said apparatus to achieve such sterilisation by optimising the power output (or absorbed) by the apparatus itself.

Said object is achieved in full by means of the apparatus of the present invention, which is characterised as described in the claims below and in particular by the fact that the guide means are configured in such a way that, when the closures are passing inside the sterilisation station, the upper wall thereof is inclined in relation to said directions of irradiation.

The apparatus of the present invention is further characterised in that the guide means are disposed asymmetrically in relation to the emitters in the sterilisation station.

BRIEF DESCRIPTION OF THE DRAWINGS.

These and other characteristics will become more apparent from the following description of a preferred embodiment, illustrated solely by way of a non-restrictive example in the appended drawings, in which:

- figure 1 illustrates a partially exploded perspective view of an apparatus according to the invention;

- figure 2 illustrates a detail of the apparatus of figure 1 in another perspective view;

- figure 3 illustrates a sectional view of the apparatus of figure 1;

- figure 4 illustrates the apparatus of figure 3 according to one embodiment thereof;

- figure 5 illustrates a sectional view of the apparatus of figure 1 according to one embodiment thereof.

BEST MODE FOR CARRYING OUT THE INVENTION.

In the figures, 1 indicates an apparatus for sterilising container closures 2. Said closures 2 consist in particular of caps or stoppers made, for example, of polymeric materials (such as PET and HDPE).

Each closure 2 defines a lateral wall 3 suitable for engaging the mouth of a container and an upper wall 4 suitable for closing said mouth. In practical terms, the lateral wall 3 is comprised of a substantially ring-shaped body with a cylindrical or slightly tapered geometry; the upper wall 4 is comprised of a disk- or dome-shaped body attached to one edge of the lateral wall.

Each closure 2 thus defines a concave portion, i.e. one having an aperture.

The apparatus 1 comprises a first ionising radiation emitter 5 A and a second ionising radiation emitter 5B. Preferably, such emitters 5 are electron cannons.

The emitters 5 are oriented in prefixed directions of irradiation and positioned on opposite sides relative to a travel path followed by the closures 2 inside the apparatus

1, so that said radiation is irradiated on opposite portions of each closure 2.

In this connection, it should be observed that the closures 2 pass inside the apparatus along a pre-established direction defined by the guide means 6 of the closures 2 themselves.

In a portion of space wherein the- emitters 5 irradiate ionising radiation, a sterilisation station is defined, through which the closures 2 pass individually, thus becoming sterilised.

Thus the guide means 6 operatively permit the closures 2 to be fed to the sterilisation station, hi this respect, it should be observed that in figure 1 the number 9 indicates a rotary star, constituting spacer means to deliver the closures 2 to the sterilisation station at evenly spaced intervals, said spacer means being operatively associated with said guide means 6 and positioned upstream from the sterilisation station. The emitters 5 are positioned on opposite sides of the guide means 6 so as to intercept the closures 2 with said radiation in the sterilisation station. In this manner, each closure 2 receives radiation both on the outer portion (i.e. the portion that remains on the outside of the container when the closure is applied on the mouth of the container to close it), consisting of the outer surface of the upper wall 4 and lateral wall 3, and on the concave portion, consisting of the inner surface of the lateral wall 3 and the inner surface of the upper wall 4. The guide means are configured in an original manne I r so t ihat when the closures 2

I pass through the sterilisation station, the upper wall 4 thereof is inclined in relation to the diiectioiis of irradiation. ^■

The expression "upper wall 4 inclined in relation to the directions of irradiation" means that said upper wall 4 shall form an angle greater than 0 degrees and less than

90 degrees relative to the directions of irradiation.

Said angle (of inclination between the upper wall of the clpsures 2 disposed in the sterilisation station and the directions of irradiation) shall preferably be between 65 and 88 degrees.

This corresponds, advantageously, to an inclination sufficient to permit an effective sterilisation of the most critical zones of the closure (those that are normally obscured), without preventing the closure itself from rolling correctly.

More preferably, said angle (of inclination between the upper wall of the closures 2 disposed in the sterilisation station and the directions of irradiation) shall be approximately 80 degrees.

In the preferred embodiment illustrated, the closures pass inside the sterilisation station along a path lying on a longitudinal plane, and . more specifically in a longitudinal direction.

The emitters 5 are oriented in transverse directions, i.e. perpendicularly to the travel path of the caps 2 in the sterilisation station. .

Furthermore, the emitters 5 are preferably facing each other, so as to irradiate the respective ionising radiation substantially in a same direction, from opposite sides.

It shall also be observed that the emitters 5 are provided with respective emission windows 7 having a shape elongated along the travel path of the closures (defined by the guide means 6). . ,

In the preferred embodiment illustrated, the guide means 6 comprise a plurality of rod-shaped elements .8_. disposed along the feed path of the closures 2 to support them and ^"permit, the passage thereof into the sterilisation station. . _,

In particular, the rod-shaped , elements 8^ are longitudinally disposed so as to constitute constraint means for the closures 2 and prevent deviations of the closures 2 themselvs from the desired travel path. .... !

The rod-shaped elements 8' are.Gonfigured.so as to permit the closures 2 to. roll along the travel path (or in said longitudinal direction). ■^"■ . In this connection, it should be observed that the outer surface of the rod-shaped elements 8 define a roughness coefficient that is at least equal to a pre-established value.

The rod-shaped elements 8 are preferably inclined downwards so as to permit the closures 2 to be fed by gravity.

It should be observed that the rod-shaped elements are preferably comprised of tubes

(for example with a circular cross-section) internally defining corresponding passages for a cooling fluid. ,

In the preferred embodiment illustrated, the guide means 6 comprise:

- a first rod-shaped element 8A disposed on a first longitudinal plane to support the lateral wall 3 of the closures 2 and permit them to roll over itself;

- a second rod-shaped element 8B disposed on a second longitudinal plane, situated at prefixed distance from the first, to support the upper wall 4 of the closures and permit them to slide over it;

- a third rod-shaped element 8C disposed on an intermediate longitudinal plane between the first and second longitudinal plane to support the upper wall 4 of the closures and permit them to slide on it.

The third rod-shaped element 8C and the second rod-shaped element 8B are parallel and lie on a plane that is inclined, relative to the direction of irradiation, by an angle equal to the desired angle of inclination for the closures 2 (as described above). It should be observed that the rod-shaped element 8C, in combination with the , second rod-shaped element 8B, lends particular stability to the closures 2 and prevents the risk of them slipping out of place while in motion; however, the presence of the. third rod-shaped element 8C is not essential, since the combination of the first rod-shaped element 8 A and second rod-shaped element 8B constitutes φer se a constraint means suitable for guiding the caps along the desired path and with the desired inclination, as the caps are made to roll over the first rod-shaped element 8 A.

In this connection, it shall be noted in particular that the first rod-shaped element 8A is configured so as to induce a rolling motion (and prevent sliding) of the lateral wall

3 of the closures 2 over itself.

The guide means 6 described above are suitable for guiding the closures 2, whose lateral wall 3 may have either a tapered or cylindrical geometry. hi this connection, it should be observed that, for the treatment of closures whose lateral wall 3 has a tapered geometry, a variant embodiment of the present apparatus

(not illustrated in the figures but described below) is provided for the guide means 6,

According to said variant embodiment, the guide means 6 comprise:

- a first rod-shaped element disposed on a first longitudinal plane to support the lateral wall 3 of the closures 2 and permit them to roll over it (wholly equivalent to the first rod-shaped element 8A described above and illustrated in the figures);

- a second rod-shaped element 8D disposed on a second longitudinal plane at a prefixed distance from the first, to provide an upper constraint for the lateral wall 3 t of the closures 2.

The tapered shape of the closures 2 makes it possible, in fact, to avoid the presence of rod-shaped elepents to support the outer part of the upper wall 4 of the closures 2. In this connection, it should be observed that the presence Qf rod-shaped elements (and more generally speaking of guide means 6) may give rise to two drawbacks:

- a shadow effect on the closure, associated with the presence of a rod-shaped element interposed between one of the emitteis 5 and a portion of the closure, such as to constitute an obstacle to the irradiation of ionising radiation; in fact, any element interposed between a closure and an emission window 7 will absorb part of 10

the irradiated electrons and create shadow zones;

- complications and costs tied to the necessity of cooling the rod-shaped elements (or in any case the guide means) disposed in the sterilisation station.

In this connection, it should be observed that the present invention advantageously allows the space occupied by the guide means to be minimised without prejudicing the stability of the closures 2; this results in an elimination of the shadow effect and a reduction in the flow of refrigerant fluid.

It should be observed that the concave portion of the closures is especially difficult to sterilise, since the shape (or constructive geometry) of the closure 3 itself produces a shielding effect on the surface corresponding to the concave portion.

It is hence particularly advantageous to avoid obstacles to the irradiation directed at said concave portion of the closures 2.

In this connection, it should be observed that the present invention makes it possible, in an original manner, not only to reduce the number of rod-shaped elements 8 of s the guide means 6 to a minimum, but also to place the rod-shaped elements 8 necessary to ensure the stability of the closures 2 in a position such as not to interfere with said concave portion. In fact, the volume of space lying between the concave portions of the closures 2 disposed in the sterilisation station and the emitter 5 A oriented toward them is freed,

I in an original manner, of rod-shaped elements 8, so that the radiation of the emitter can intercept the inner surface of said concavity without meeting obstacles. It should be observed that the inclination of the closures (or rather, of the upper surface 4 thereof) in relation to the direction of irradiation has precisely the effect of improving the efficacy of the ionising radiation irradiated on the concave portion of the closures 2. Said inclination allows, in an original manner, the desired dose of irradiation to reach the area around the inside corners of the closures 2, thereby achieving a particularly uniform exposure.

In this connection, the rolling of the closures combines in a synergetic manner with said inclination of the radiation irradiated, since it guarantees that the entire portion of the closure will be uniformly exposed to radiation.

The fact that the emission windows 7 of the emitters 5 are elongated in the direction of travel of the closures (for example longitudinally) also combines in a synergetic manner with said characteristics (inclination and rolling), since it allows the concave portion of the caps to be irradiated in a complete and uniform manner and for a prolonged time.

According to another aspect of the present invention (schematically illustrated in figure 5), the apparatus 1 comprises means (not illustrated in the figures because of a type known per se) for changing the orientation of the emitters 5 in relation to the guide means 6 so as to adjust the relative inclination between the upper wall 4 of the closures 2 disposed in the sterilisation station and the directions of irradiation. Such means for changing the orientation of the emitters 5 provide two advantages: - the angle of inclination (i.e. the angle of incidence of the ionising radiation on the surfaces of the closures to be sterilised) can be changed in a simple and convenient manner, without there being any need to replace the guide means, so that the inclination can be adjusted also based on the type of closures treated or other parameters of the sterilisation system;

-^■ an inclination (between the upper surface 4 of the closures 2 disposed in the sterilisation station and the direction of irradiation) is obtained using guide means of a traditional type (i.e. guide means which induce a movement of the closures 1 positioned vertically).

According to a further aspect of the present invention, the guide means 6 are disposed asymmetrically in relation to the emitters 5 in the sterilisation station.

In particular, the guide means 6 are disposed in such a manner that when the closures

2 pass inside the sterilisation station they will be situated at a smaller distance from the emitter 5 A, oriented toward the concave portion of the closures 2 themselves, than.from the other emitter 5B.

An asymmetry in. the positioning of the closure descent channel (that is to say in the travel path of the closures) relative to .the emitters 5 positioned opposite each other makes it possible to, increase the dose of radiation irradiated on the concave portion of the closure particularly difficult to sterilise), as compared to the opposite portion

(easier to sterilise). _. _ ,

Said asymmetry, in fact, allows the following advantages.

Firstly, said asymmetry allows both the concave portion and opposite portion (outer) of the closures to be treated simultaneously and. in an optimal manner (i.e. by exploiting the, power output by the emitters in an optimal manner) using two emitters

5 ^' on opposite sides of the guide means 6 and mutually aligned in a direction of irradiation. . ,

It should be observed that if the, guide is symmetrically positioned in relation to the emitters;, a simultaneous _. treatment of the two opposite faces of the closures (by rneans of emitters that are aligned aηd positioned opposite each other) would result in a non-optimal division of the energy. output by the. emitters, to the disadvantage of the concave portion (the" most difficult to sterilise) of the closure: , ^• It shall further^" be noted that the simultaneous treatment of the' two opposite faces of the closures (by means of .emitters that are aligned and positioned opposite each other) has the advantage of preventing re-contamination. If the two opposite surfaces of the closure were to be treated at different times, there would be the risk of microorganisms moving over from the surface not yet treated to the already sterilised one, resulting in the re-contamination thereof due to the environment in which the closures are immersed in the sterilisation station, which comprises air in a turbulent regime.

Furthermore, said asymmetry allows the power of the emitter intended to treat the concave part of the closures 2 to be optimally exploited by reducing the operative distance between the closures disposed in the sterilisation station and emission window 7. At the same time, the asymmetry also allows for a minimum distance to be maintained between the emission windows 7 of the two emitters 5 positioned opposite each other, which is necessary to avoid damaging the windows 7 of the emitters (for example, any thin titanium foils covering the windows 7 may be susceptible to damage).

In this connection, the apparatus 1 also comprises adjustment means (not illustrated because of a type known per se) for adjusting the distances of the guide means 6 in relation to the emitters 5. ,

Such adjustment means render the apparatus particularly flexible and enable the operation thereof to be optimised according to the type of closures treated and parameters of the sterilisation system, in light of what has been described above.

It should be observed that the technical characteristic tied to the asymmetry of the

! guide means 6 in relation to the emitters 5 may be employed in the apparatus 1 either separately or in combination with the technical characteristic tied to the inclination of the closures 2 in relation to the directions of sterilisation. i ! t i

When such characteristics are used in combination, the respective effects thereof are synergically combined.

However, each of the above-mentioned characteristics can be individually implemented, as this would provide in any case an advantage, namely, that of contributing to solve the problem of sterilising the concave portion of the closures 2 by optimising the resources employed in the operation of the apparatus 1.

Claims

1. Apparatus (1) for sterilising container closures (2), said closures being defined by a lateral wall (3) suitable for engaging the mouth of a container and an upper wall (4) suitable for closing said mouth, comprising:

- guide means (6) for feeding the closures (T) to a sterilisation station;

- a first and second emitter (5) of ionising radiation oriented in prefixed directions of irradiation and positioned on opposite sides of the guide means (6) so as to intercept the closures (2) with said radiation in the sterilisation station, characterised in that the guide means (6) are configured in such a way that, when the closures (2) are passing inside the sterilisation station, the closures (2) are positioned with the upper wall (4) inclined in relation to said directions of irradiation.

2. Apparatus according to claim 1, wherein the guide means (6) comprise a plurality of rod-shaped elements (8) disposed along a feed path of the closures (2) to support them and permit the rolling thereof.

3. Apparatus according to claim 1 or 2, wherein the guide means (6) are inclined downward to permit the closures (2) to be fed by gravity.

4. Apparatus according to any of the previous claims, wherein the guide means (6) are disposed on longitudinal planes and the emitters (5) are oriented in a transverse direction from opposite sides.

5. Apparatus according to any of the previous claims, wherein the guide means

(6) are configured so that the closures (2) are disposed with the upper wall (4) inclined in relation to said directions of irradiation by an angle ranging between 65 degrees and 88 degrees.

6. Apparatus according to claim 5, wherein the guide means (6) are configured so that the closures (2) are disposed with the upper wall (4) inclined in relation to said directions of irradiation by an angle of approximately 80 degrees.

7. Apparatus according to claim 2, wherein the guide means (6) comprise:

- a first rod-shaped element (8A) arranged on a first longitudinal plane to support the lateral wall (3) of the closures (2) and permit them to roll over itself;

- a second rod-shaped element (8B) arranged on a second longitudinal plane, situated at a prefixed distance from the first, to support the upper wall (4) of the closures and permit them to slide over it.

8. Apparatus according to claim 2, wherein the guide means (6) comprise:

- a first rod-shaped element (8A) arranged on a first longitudinal plane to support the

1 ' lateral wall (3) of the closures (2) and permit them to roll over itself;

- a second rod-shaped element (8D) arranged on a second longitudinal plane, situated at a prefixed distance from the first, to provide an upper constraint for the lateral wall

(3) of the closures, the lateral wall (3) of the closures (2) being tapered.

9. Apparatus according to claim 7 or 8, wherein the first rod-shaped element (8B) is configured so as to induce the lateral wall (3) of the closures to roll over it avoiding sliding.

10. Apparatus according to claim 2, wherein the volume of space lying between the concave portions of the closures (2) disposed in the sterilisation station and the emitter (5A) oriented toward them is fiee of rod-shaped elements (8), so that the radiation delivered by the emitter can intercept the inner surface of said concavity without meeting obstacles.

11. Apparatus according to any of the previous claims, comprising means for changing the orientation of the emitters (5) in relation to the guide means (6), so as to adjust the relative inclination between the upper wall (4) of the closures (2) arranged in the sterilisation station and the directions of irradiation.

12. Apparatus according to any of the previous claims, wherein the guide means (6) are arranged asymmetrically in- relation to the emitters (5) in the sterilisation station.

13. Apparatus according to claim 12, wherein the guide means (6) are arranged in such a way that when the closures (2) pass inside the sterilisation station they are situated at a smaller distance from the emitter (5A) oriented toward the concave pprtion of the closures (2) themselves than from the other emitter (5B).

14. Apparatus according to claim 12 or 13, comprising means for adjusting the distances of the guide means (6) in relation to the emitters (5).

15. Apparatus (1) for sterilising container closures (2), said closures being defined by a lateral wall (3) suitable for engaging the mouth of a container and an upper wall (4) suitable for closing said mouth, comprising:

- guide means (6) for feeding the closures (2) to a sterilisation station;

- a first and second emitter (5) of ionising radiation oriented in prefixed irradiation directions and positioned on opposite sides of the guide means (6) to intercept the closures (2) with said radiation in the sterilisation station, characterised in that the guide means (6) are disposed asymmetrically in relation to the emitters (5) in the sterilisation station.