DE102007050582B4 - Method and device for sterilizing and device for blow molding of containers - Google Patents

Abstract

Method for sterilizing workpieces made of a thermoplastic material in the production of blow-molded containers, wherein a preform (1) is sterilized as a workpiece, characterized in that the sterilization is carried out by applying an electron beam, the electron radiation having a radiation intensity of at least 15 kGy is directed to the surface of the workpiece.

Description

The invention relates to a method for sterilizing workpieces made of a thermoplastic material in the manufacture of blow-molded containers.

In addition, the invention relates to a method for blow molding at least partially sterile containers.

Finally, the invention relates to a device for sterilizing workpieces made of a thermoplastic material in the production of blow-molded containers. Also, the invention comprises an apparatus for producing at least partially sterile workpieces made of a thermoplastic material.

The invention also relates to a device for blow-molding containers, which has at least one blowing station arranged on a support structure for shaping thermoplastic preforms into the containers.

Manufacture of sterile blow-molded containers is typically done by sterilizing these containers after they have been blow-molded and filled before using hydrogen peroxide or other chemicals. It is also already known to sterilize the preforms used in the blow-molding of the containers as starting material, in particular the area of the inner surface of these preforms.

It is also already known that when performing a coating of containers using a plasma sterilization effects occur. Due to the usually provided contours in the region of the container walls, however, so-called shadings occur in such sterilizations, which preclude reliable sterilization.

Generally, in the sterilization of containers and preforms, a distinction is made between wet sterilization using liquid sterilants and dry sterilization using, for example, dried hot air or superheated steam. Another way to sterilize preforms or containers is to use high energy radiation to kill bacterial spores and germs.

In case of container molding by blowing pressure, preforms made of a thermoplastic material, for example preforms made of PET (polyethylene terephthalate), are fed to different processing stations within a blow molding machine. Typically, such a blow molding machine has a heating device and a blowing device, in the region of which the previously tempered preform is expanded by biaxial orientation to form a container. The expansion takes place with the aid of compressed air, which is introduced into the preform to be expanded. The procedural sequence in such an expansion of the preform is in the DE 43 40 291 A1 explained.

The basic structure of a blowing station for container molding is in the DE 42 12 583 A1 described. Possibilities for tempering the preforms are in the DE 23 52 926 A1 explained.

Within the blow molding apparatus, the preforms as well as the blown containers can be transported by means of different handling devices. In particular, the use of transport mandrels, onto which the preforms are plugged, has proven to be useful. The preforms can also be handled with other support devices. The use of gripper tongs for handling preforms and the use of expansion mandrels which are insertable into a muzzle region of the preform for mounting are also among the available constructions.

Handling of containers using transfer wheels, for example, in the DE 199 06 438 A1 in an arrangement of the transfer wheel between a blowing wheel and an output path described.

The already described handling of the preforms is carried out on the one hand in the so-called two-stage process in which the preforms are suitably tempered immediately after their injection molding production and sufficient solidification and then inflated.

With regard to the blow molding stations used, different embodiments are known. In blow stations, which are arranged on rotating transport wheels, a book-like unfoldability of the mold carrier is frequently encountered. But it is also possible to use relatively movable or differently guided mold carrier. In fixed blowing stations, which are particularly suitable for receiving a plurality of cavities for container molding, typically plates arranged parallel to one another are used as mold carriers.

Methods and devices for sterilizing workpieces or articles are known from a number of publications.

That's how it describes EP 1 406 590 B1 a process for the preparation of articles of polymeric materials with drug depot effect. Crosslinking and sterilization of the article take place by means of electron radiation.

In the same way concerns the EP 1 374 915 A1 Method for sterilizing impression materials, which in turn uses electron beam radiation.

The EP 1 198 505 B1 describes the sterilization of a molded or extruded article from a carbonate polymer composition by electron beam during manufacture.

From the WO 2005/080495 A1 For example, there is known a sterilization of a finished article produced, which can be made by, among other things, blow molding and stretch blow molding.

The post-published DE 10 2007 017 938 B4 describes a device for blow molding containers with a blow molding machine, on or on which a radiation emitter is mounted, which may be an electron gun.

The object of the present invention is to improve a method of the aforementioned type such that a reliable sterilization can be carried out in a simple manner.

This object is achieved in that the sterilization is carried out by applying an electron beam, wherein the electron beam is conducted with a radiation intensity of at least 15 kGy on the surface of the workpiece, wherein the workpiece is a preform.

Another object of the present invention is to construct a device of the aforementioned type such that an effective sterilization with little effort is feasible.

This object is achieved in that at least one sterilization unit has a generator for electron radiation, wherein the generator has a power output for generating a radiation intensity in the region of a surface of the workpiece of 15 kGy, and wherein the sterilization unit is designed for sterilization of preforms.

Finally, it is an object of the present invention to construct a device for blow-molding of containers of the aforementioned type such that the production of sterile containers is supported.

This object is achieved in that along a part of a transport path of the preforms a sterilization unit is arranged, which is provided with a generator for electron radiation.

For a variety of applications, it is sufficient that an inner surface of the preforms be sterilized.

In addition, however, it is also thought that an outer surface of the preforms is sterilized.

Effective sterilization is accomplished by exposing each part of the surface of the preform to an electron beam.

An advantageous orientation of the radiation source takes place in that the electron beam is aligned with an angle range of 0 to 15 ° relative to a surface normal of the surface.

A structurally simple realization is supported by the fact that the electron beam is generated by a radiation source.

A further embodiment variant is that the electron beam is generated by at least two radiation sources.

A uniform loading of the preform in a circumferential direction is facilitated by the fact that the workpiece is at least temporarily offset in rotation about its longitudinal axis during the implementation of the sterilization process.

In order to act on the surface of the preform in a longitudinal direction, it is proposed that the sterilization unit be pivoted at least temporarily during the performance of the sterilization process.

An arrangement of the sterilization unit can be carried out, for example, such that the preform is sterilized in the region of a feed section.

Another arrangement variant is provided in that a sterilization of the preforms in the transport direction before a heating section and after a performed arrangement of the preforms is carried out at constant intervals relative to each other.

Another constructive realization is that the sterilization unit is arranged displaceably.

A compact construction of the device is supported by the fact that the sterilization unit is at least partially rod-shaped.

• 1 Eine perspektivische Darstellung einer Blasstation zur Herstellung von Behältern aus Vorformlingen,
• 2 einen Längsschnitt durch eine Blasform, in der ein Vorformling gereckt und expandiert wird,
• 3 eine Skizze zur Veranschaulichung eines grundsätzlichen Aufbaus einer Vorrichtung zur Blasformung von Behältern,
• 4 eine modifizierte Heizstrecke mit vergrößerter Heizkapazität,
• 5 einen Längsschnitt durch einen Vorformling mit seitlich neben dem Vorformling verschwenkbar angeordneter Sterilisiereinheit,
• 6 eine gegenüber 5 abgewandelte Ausführungsform mit einer verschieblich angeordneten Sterilisiereinheit,
• 7 eine nochmals abgewandelte Ausführungsform mit einer verschwenkbaren Sterilisiereinheit zur Sterilisierung einer inneren Oberfläche des Vorformlings,
• 8 eine Ausführungsform mit einer stabartigen Sterilisiereinheit zum Einführen in einen Innenraum des Vorformlings,
• 9 eine schematische Darstellung einer Sterilisiereinheit zum Sterilisieren der inneren Oberfläche eines Behälters und
• 10 eine schematische Darstellung einer Sterilisiereinheit zum Sterilisieren der äußeren Oberfläche eines Behälters.

In the drawings, embodiments of the invention are shown schematically. Show it:

• 1 A perspective view of a blowing station for the production of containers from preforms,
• 2 a longitudinal section through a blow mold, in which a preform is stretched and expanded,
• 3 a sketch to illustrate a basic structure of a device for blow molding containers,
• 4 a modified heating section with increased heating capacity,
• 5 a longitudinal section through a preform with laterally arranged next to the preform pivotally mounted sterilization unit,
• 6 one opposite 5 modified embodiment with a displaceably arranged Sterilisiereinheit,
• 7 a further modified embodiment with a pivotable sterilization unit for sterilizing an inner surface of the preform,
• 8th an embodiment with a rod-like sterilization unit for insertion into an interior of the preform,
• 9 a schematic representation of a sterilization unit for sterilizing the inner surface of a container and
• 10 a schematic representation of a sterilization unit for sterilizing the outer surface of a container.

Before explaining the detailed structure of the device for sterilizing the workpieces by applying an electron beam and before explaining a concrete installation of a corresponding device in a blow molding machine, the basic structure of a blow molding machine will first be described below.

The basic structure of a device for forming preforms ( 1 ) in containers ( 2 ) is in 1 and in 2 shown.

The device for forming the container ( 2 ) consists essentially of a blowing station ( 3 ), which are blown ( 4 ) into which a preform ( 1 ) can be used. The preform ( 1 ) may be an injection-molded part of polyethylene terephthalate. To enable insertion of the preform ( 1 ) in the blow mold ( 4 ) and to allow removal of the finished container ( 2 ) the blow mold ( 4 ) from mold halves ( 5 . 6 ) and a bottom part ( 7 ), which by a lifting device ( 8th ) is positionable. The preform ( 1 ) in the area of the blowing station ( 3 ) of a transport mandrel ( 9 ), which together with the preform ( 1 ) passes through a plurality of treatment stations within the device. But it is also possible to use the preform ( 1 ), for example via pliers or other handling means directly into the blow mold ( 4 ).

To enable a compressed air supply line is below the transport mandrel ( 9 ) a connecting piston ( 10 ) disposed of the preform ( 1 ) Supplies compressed air and at the same time a seal relative to the transport mandrel ( 9 ). In a modified construction, it is basically also conceivable to use solid compressed air supply lines.

A stretching of the preform ( 1 ) takes place with the aid of a stretching rod ( 11 ), by a cylinder ( 12 ) is positioned. Basically, it is also conceivable, a mechanical positioning of the stretch rod ( 11 ) via curve segments that are acted upon by Abgriffrollen. The use of curve segments is particularly useful when a plurality of blow molding stations ( 3 ) are arranged on a rotating blowing wheel. A use of cylinders ( 12 ) is useful when stationarily arranged blow molding stations ( 3 ) are provided.

At the in 1 illustrated embodiment, the stretching system is designed such that a tandem arrangement of two cylinders ( 12 ). From a primary cylinder ( 13 ), the stretch rod ( 11 ) first before the beginning of the actual stretching process into the area of a soil ( 14 ) of the preform ( 1 ) hazards. During the actual stretching process, the primary cylinder ( 13 ) with extended stretch rod together with a primary cylinder ( 13 ) carrying carriages ( 15 ) from a secondary cylinder ( 16 ) or via a cam control. In particular, the secondary cylinder ( 16 ) such a cam-controlled use that of a leadership role ( 17 ), which slides along a curved path during the execution of the stretching process, a current stretching position is specified. The leadership role ( 17 ) is from the secondary cylinder ( 16 ) pressed against the guideway. The sled ( 15 ) slides along two guide elements ( 18 ).

After closing in the range of girders ( 19 . 20 ) arranged mold halves ( 5 . 6 ) there is a locking of the carrier ( 19 . 20 ) relative to each other by means of a locking device ( 40 ).

For adaptation to different shapes of a mouth section ( 21 ) of the preform ( 1 ) is according to 2 the use of separate thread inserts ( 22 ) in the area of the blow mold ( 4 ) intended.

2 shows in addition to the blown container ( 2 ) also shown in dashed lines the preform ( 1 ) and schematically a developing container bubble ( 23 ).

3 shows the basic structure of a blow molding machine with a heating line ( 24 ) and a rotating blowing wheel ( 25 ) is provided. Starting from a preform input ( 26 ), the preforms ( 1 ) of transfer wheels ( 27 . 28 . 29 ) in the area of the heating section ( 24 ). Along the heating route ( 24 ) are radiant heaters ( 30 ) as well as blowers ( 31 ) arranged to the preforms ( 1 ) to temper. After a sufficient temperature of the preforms ( 1 ) these are to the blowing wheel ( 25 ), in whose area the blowing stations ( 3 ) are arranged. The finished blown containers ( 2 ) are provided by further transfer wheels of a delivery line ( 32 ).

To get a preform ( 1 ) into a container ( 2 ) that the container ( 2 ) Has material properties which have a long useful life from inside the container ( 2 ), in particular beverages, special process steps in the heating and orientation of the preforms ( 1 ) be respected. In addition, advantageous effects can be achieved by adhering to special dimensioning regulations.

As a thermoplastic material different plastics can be used. For example, PET, PEN or PP can be used.

The expansion of the preform ( 1 ) during the orientation process is carried out by compressed air supply. The compressed air supply is in a Vorblasphase in which gas, for example, compressed air, is supplied at a low pressure level and divided into a subsequent Hauptblasphase in which gas is supplied at a higher pressure level. During the pre-blowing phase, compressed air is typically used at a pressure in the interval of 10 bar to 25 bar and during the main blowing phase compressed air is supplied at a pressure in the interval of 25 bar to 40 bar.

Out 3 is also apparent that in the illustrated embodiment, the heating section ( 24 ) from a plurality of circulating transport elements ( 33 ) is formed, the chain-like strung together and along deflection wheels ( 34 ) are guided. In particular, it is envisaged to open a substantially rectangular basic contour by the chain-like arrangement. In the illustrated embodiment, in the region of the transfer wheel ( 29 ) and an input wheel ( 35 ) facing the extent of the heating section ( 24 ) a single relatively large-sized deflection ( 34 ) and in the region of adjacent deflections two comparatively smaller dimensioned deflection wheels ( 36 ) used. In principle, however, any other guides are conceivable.

To enable a dense arrangement of the transfer wheel ( 29 ) and the input wheel ( 35 ) relative to each other, the arrangement shown to be particularly useful, since in the region of the corresponding extent of the heating section ( 24 ) three deflection wheels ( 34 . 36 ), in each case the smaller deflection wheels ( 36 ) in the area of the transition to the linear curves of the heating section ( 24 ) and the larger deflection wheel ( 34 ) in the immediate transfer area to the transfer wheel ( 29 ) and to the input wheel ( 35 ). Alternatively to the use of chain-like transport elements ( 33 For example, it is also possible to use a rotating heating wheel.

After a finished blowing of the container ( 2 ), these are picked up by a picking wheel ( 37 ) from the field of blowing stations ( 3 ) and via the transfer wheel ( 28 ) and an output wheel ( 38 ) to the output section ( 32 ).

In the in 4 illustrated modified heating section ( 24 ) can by the larger number of radiant heaters ( 30 ) a larger amount of preforms ( 1 ) are tempered per unit time. The blowers ( 31 ) direct cooling air into the area of cooling air ducts ( 39 ), which the associated radiant heaters ( 30 ) in each case opposite and deliver the cooling air via outflow openings. Due to the arrangement of the outflow directions, a flow direction for the cooling air is substantially transverse to a transport direction of the preforms ( 1 ) realized. The cooling air channels ( 39 ) in the area of the radiant heaters ( 30 ) opposite surfaces provide reflectors for the heating radiation, it is also possible on the discharged cooling air and a cooling of the radiant heater ( 30 ) to realize.

5 shows a longitudinal section through a preform ( 1 ). The preform ( 1 ) has a wall ( 41 ), which have an outer surface ( 42 ) and an interior ( 43 ) facing inner surface ( 44 ) is provided. On the outside next to the preform ( 1 ) is a sterilization unit ( 45 ), which is formed as an electron beam generator and an electron beam ( 46 ) towards the outer surface ( 42 ). In the illustrated embodiment, the sterilization unit ( 45 ) in the direction of a Longitudinal axis ( 47 ) of the preform ( 1 ) arranged pivotably.

The preform ( 1 ) during its sterilization process about its preform longitudinal axis ( 47 ) in a rotation around. For example, it is possible, in each case after a complete rotation through 360 °, to pivot the sterilization unit (FIG. 45 ) in such a way that successively in the direction of the longitudinal axis ( 47 ) one after the other ring-like or sleeve-like segments of the outer surface ( 42 ) are sterilized.

6 shows one opposite 5 modified embodiment in which the sterilization unit ( 45 ) is not pivotable, but in the direction of the longitudinal axis ( 47 ) is arranged displaceably. In particular, the sterilization unit ( 45 ) substantially parallel to the longitudinal axis ( 47 ), so that a constant distance between the sterilization unit ( 45 ) and the outer surface ( 42 ) is guaranteed. In principle, it is also possible to have both a displaceability and a pivotability of the sterilization unit ( 45 ) to realize.

According to the embodiment in FIG 7 is the sterilization unit ( 45 ) near the mouth section ( 21 ) of the preform ( 1 ) arranged. The arrangement of the sterilization unit ( 45 ) takes place in such a way that the electron beam ( 46 ) through a mouth opening ( 48 ) of the preform ( 1 ) in the interior ( 43 ) and here on the inner surface ( 44 ). Preferably, the sterilization unit ( 45 ) pivotally arranged to different sterilization areas in the direction of the longitudinal axis ( 47 ). Also for such internal sterilization of the preform ( 1 ), it proves to be expedient to use the preform ( 1 ) during the sterilization process in a rotational movement about the longitudinal axis ( 47 ) around.

In the case of pivotable sterilization units ( 45 ), it is possible to perform the panning operation continuously or stepwise. In an overlay with a rotational movement of the preform ( 1 In this way, either the already mentioned annular sterilization areas or a spirally extending sterilization area can be generated.

8th shows a further modified embodiment in which a rod or tubular sterilization unit ( 45 ) in the interior ( 43 ) of the preform ( 1 ) is retracted. The sterilization unit ( 45 ) is in this case in the direction of the longitudinal axis ( 47 ) positionable. The electron beam ( 46 ) can either be fan-shaped to 360 °, or at a certain time only a certain angle section of the inner surface ( 44 ). In such a focusing of the electron beam ( 46 ), the sterilization unit ( 45 ) and / or the preform ( 1 ) about the longitudinal axis ( 47 ) turned around. Between the rod-shaped sterilization unit ( 45 ) and the inner surface ( 44 ) extends a distance ( 49 ).

All in the 5 to 8th illustrated arrangements and modes of operation of the sterilization unit ( 45 ) can also be used to sterilize blown containers ( 2 ) be used. 9 shows by way of example the arrangement of a sterilization unit ( 45 ) in the container ( 2 ) and 10 an arrangement on the outside next to the container ( 2 ).

The electron beam ( 46 ) can be generated in all embodiments either from one or more electron beam sources. It is also possible to use the electron beam generated by one or more electron beam sources ( 46 ) in a uniform electron beam or several different beam paths in the direction of the preform ( 1 ) or the container ( 2 ). Typically, the electron beam ( 46 ) is aligned with its major axis substantially perpendicular to the surface to be sterilized. Typically, a corresponding alignment range is in the range of 0 to 15 °, wherein in addition the already explained pivoting movements can be performed.

A typical level of electron radiation is chosen such that a radiation intensity of at least 15 kGy is achieved in each surface area to be sterilized. As a result, a sterilization of at least log 3 in terms of germs, bacteria and spores is achieved.

In a sterilization of preforms ( 1 ), the sterilizer unit ( 45 ) in the preform input area ( 26 ), a transfer wheel ( 27 . 29 ) or in the area of the heating section ( 24 ). In case of sterilization of blown containers ( 2 ), an arrangement of the sterilization unit ( 45 ) typically in the region of a transfer wheel or in the region of the delivery path ( 32 ).

In order to maintain the achieved sterility, it is particularly conceivable to use the blown containers ( 2 ) after leaving the blowing station ( 3 ) in sterile air, which in particular is provided with a laminar flow. Preferably, the blown containers ( 2 ) is transported under such sterile conditions into the region of a filling device.

For a positionable sterilization unit ( 45 ), the respective positioning, for example, the implementation of a pivoting movement or a displacement, using a pneumatic cylinder, an electric drive or cam-controlled.

Claims (24)

Method for sterilizing workpieces made of a thermoplastic material in the production of blow-molded containers, wherein a preform (1) is sterilized as a workpiece, characterized in that the sterilization is carried out by applying an electron beam, the electron radiation having a radiation intensity of at least 15 kGy is directed to the surface of the workpiece. Method according to Claim 1 , characterized in that an inner surface of the workpiece is sterilized. Method according to Claim 1 , characterized in that an outer surface of the workpiece is sterilized. Method according to one of Claims 1 to 3 , characterized in that each part of the surface of the workpiece is acted upon by an electron beam (46). Method according to one of Claims 1 to 4 , characterized in that the electron beam (46) is aligned with an angular range of 0 to 15 ° relative to a surface normal of the surface. Method according to one of Claims 1 to 5 , characterized in that the electron beam is generated by a radiation source. Method according to one of Claims 1 to 5 , characterized in that the electron beam is generated by at least two radiation sources. Method according to one of Claims 1 to 7 , characterized in that the workpiece is at least temporarily offset in rotation about its longitudinal axis during the implementation of the sterilization process. Method according to one of Claims 1 to 8th , characterized in that the Sterilisiereinheit (45) is at least temporarily pivoted during the performance of the sterilization process. Method according to one of Claims 1 to 9 , characterized in that the preform (1) in the region of a feed line (26) is sterilized. Method according to one of Claims 1 to 9 , characterized in that the sterilization of the preforms (1) in the transport direction in front of a heating section (24) and after a performed arrangement of the preforms (1) is carried out at constant intervals relative to each other. Method according to one of Claims 1 to 11 , characterized in that the workpiece is moved together with the sterilization unit (45) along a transport path. Device for sterilizing workpieces made of a thermoplastic material in the production of blow-molded containers, wherein the sterilization unit (45) for sterilizing preforms (1) is formed as a workpiece, characterized in that at least one sterilization unit (45) has a generator for electron radiation wherein the generator has a power output for generating a radiation intensity in the region of a surface of the workpiece of at least 15 kGy. Device after Claim 13 , characterized in that the Sterilisiereinheit (45) is designed to act on the entire area of the surface to be sterilized of the workpiece. Device after Claim 13 or 14 , characterized in that the sterilization unit (45) is aligned with a main radiation direction in a range of 0 to 15 ° relative to a surface normal of the surface to be sterilized. Device according to one of Claims 13 to 15 , characterized in that the sterilization unit (45) has an electron beam source. Device according to one of Claims 13 to 15 , characterized in that the Sterilisiereinheit (45) has at least two electron beam sources. Device according to one of Claims 13 to 17 , characterized in that the workpiece to be sterilized is coupled to a rotary drive. Device according to one of Claims 13 to 18 , characterized in that the Sterilisiereinheit (45) is arranged pivotably. Device according to one of Claims 13 to 19 , characterized in that the sterilization unit (45) is arranged in the region of a feed path of the preforms (1). Device according to one of Claims 13 to 19 , characterized in that the sterilization unit (45) is arranged in a transport direction of the preforms (1) in front of a heating section (24). Device according to one of Claims 13 to 21 , characterized in that the Sterilisiereinheit (45) is arranged displaceably. Device according to one of Claims 13 to 22 , characterized in that the Sterilisiereinheit (45) is formed at least partially rod-like. Device for the blow-molding of containers (2), which has at least one blowing station arranged on a supporting structure for forming thermoplastic preforms (1) into the containers (2), characterized in that along a transport path of the preforms (1) is a device for sterilizing Workpieces according to one of Claims 13 to 23 is arranged.

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