Freeze-drying containers

Description

[0001] The present invention relates to a freeze-drying container comprising a tub frame with a closable access opening and a circumferential wall, which has a first projection on a free edge to which a filter cloth is circumferentially attached.

[0002] Such a freeze-drying container is already known from DE 20 2019 102 094 U1. Essential for the use of such tub-shaped containers is their sterile condition and the prevention of the penetration of particles from the environment. Further reference should be made to WO 2014 / 165222 A1, US 11 377 246 B2, and WO 2006 / 013360 A1.

[0003] For example, tray systems are known for use in freeze-drying processes, which are used in the so-called lyophilization process. Such a tray system comprises a tray for the lyophilisate, above which a filter cloth is placed in a holder. It is important to ensure that such a filter cloth is sterilized beforehand to avoid the inclusion of germs that would contaminate the lyophilisate. In such a solution, the tray system is made of stainless steel, for example, and is therefore reusable, while the filter cloth must be replaced and disposed of after use.

[0004] However, this requires appropriate sterilization capacities at the point of use, which are not necessarily available. Therefore, in everyday practice, either considerable effort is required or the quality is reduced, and the sterilization of the filter cloth may be neglected.

[0005] Another product known as 'Lyoguard' is a plastic pan system that is directly welded to a filter cloth. While this solution is not reusable, it is known that welding can be performed primarily using similar materials. Therefore, the choice of materials for the pan and filter cloth is very limited.

[0006] During freeze-drying, it is advisable to precisely measure the temperature of the products enclosed in the individual freeze-drying containers in order to be able to selectively extract heat energy during the process. The closer a temperature sensor can be placed to the product, the more accurate the temperature measurement can be during the process. Ideally, the temperature sensor should be placed as close as possible to the product.

[0007] Against this background, the object of the present invention is to propose a freeze-drying container with which temperature measurement can be carried out as close as possible to the product, but which is nevertheless sealed liquid-tight.

[0008] This is achieved by a freeze-drying container according to the features of claim 1. Further useful embodiments of such a freeze-drying container can be found in the subsequent dependent claims.

[0009] In this respect, a freeze-drying container is provided, comprising a tank frame with a closable access opening and a circumferential wall, which has a first projection on a free edge, to which a filter cloth is circumferentially attached. According to the invention, such a freeze-drying container is characterized in that the filter cloth has a through-opening through which a sensor sleeve is passed or against which it rests, wherein the sensor sleeve has a connecting edge that encompasses an inlet opening for inserting a temperature sensor, and the filter cloth is sealed along its outer edge to the tank frame and around the through-opening to the adjacent material, each by means of heated element welding.

[0010] This results in a watertight and mechanically resilient connection despite the different materials used for the sensor sleeve and filter cloth. By inserting the sensor sleeve, a temperature sensor can be inserted into the interior of the product and precisely monitor the temperature during the freeze-drying process. The sensor sleeve can be placed either over the through-hole or passed through it and welded and stamped to the heating element, thus mechanically connecting it.

[0011] In a particularly preferred embodiment, opposing edges of the first projection can be connected to one another by at least one transverse web, preferably in a cross shape, which in turn has a through-opening that corresponds to the through-opening of the filter cloth and through which the sensor sleeve is passed or against which it rests. This creates a solid structure against which the sensor sleeve can rest, preventing it from bending. This also reduces the mechanical stress when inserting or removing the temperature sensor.

[0012] Furthermore, the sensor sleeve can be provided with a screw connection for the secure positioning of a temperature sensor that can be inserted into the sensor sleeve through the screw connection. This can be achieved particularly effectively using a threaded insert. On the one hand, such a screw connection provides mechanical support on the side opposite the sensor sleeve, and on the other hand, the temperature sensor can be held and fixed at the correct depth by screwing it into the threaded insert. This prevents any falsification of the measurement result due to the temperature sensor slipping.

[0013] Particularly preferably, the tray frame and / or the sensor sleeve can each be made of polyethylene, polypropylene, or polyester. When the plastic melts, a melt is created, which, under pressure, combines with the PTFE fabric of the filter cloth to form a tight and mechanically resilient bond. This creates a kind of interlocking of the plastic in the fabric.

[0014] Another advantage is that the sensor sleeve can have a metallic contact surface at its free end. This allows the temperature sensor to be pushed forward to the contact surface, which enables good heat-conducting contact with the interior of the freeze-drying container.

[0015] In a further specific embodiment, it can be provided that the filter cloth is made either from a polytetrafluoroethylene membrane which is laminated to a polytetrafluoroethylene carrier, or alternatively from a polytetrafluoroethylene membrane which is laminated to a carrier made of polyethylene, polypropylene or polyester.

[0016] Furthermore, the tank frame can have, on its side opposite the first projection, another free edge with a second projection, to which a cover film is attached, preferably welded. Such a cover film represents a particularly useful base for the freeze-drying container. Since this rarely sits completely flat in the freezing unit, a film that fits tightly against the cooling surface allows for intimate contact and will dissipate heat from the interior of the freeze-drying container particularly effectively.

[0017] It can be particularly advantageous if the cover film is made of the same material as the tub frame. In this case, welding of the same materials is easy using conventional methods, such as ultrasonic welding.

[0018] Alternatively, it is also possible, although not preferred, for the tub frame to form a closed lid on the side opposite the first projection. While this is mechanically more stable, it transfers heat less effectively than a cover foil.

[0019] The invention described above is explained in more detail below using an exemplary embodiment.

[0020] It shows Figure 1 shows a freeze-drying container in a perspective view from below onto the cover film, Figure 2 shows a sensor sleeve as a detail of the freeze-drying container according to Figure 1with a web for connecting the opposite edges of a first projection in a perspective view, Figure 3 shows an alternative design of the freeze-drying container according to Figure 2 without web in a perspective view, and Figure 4 a screw connection as a detail of the freeze-drying container according to Figure 1 in a perspective view.

[0021] Figure 1shows a freeze-drying container 1 (containment system for drying), which has a tank frame 2 as a supporting structure. The tank frame 2 forms a wall that surrounds the freeze-drying container 1 and can accommodate a product for freeze-drying. Together with a PTFE filter cloth 6, which is made of a PTFE membrane laminated to a PTFE fabric, and a cover film 7, which is transparent in this case and only indicated by hatching, the tank frame 2 surrounds a closed receiving space measuring 600 x 500 x 55 mm for the product to be dried. This product is introduced via a tightly sealable access opening 3.

[0022] After the freeze-drying container 1 with the product has been transferred to a freezer, the product is to be freeze-dried. The liquid should escape through the filter cloth 6, but nothing should be able to reach the product. The filter cloth 6 is therefore welded all the way to the tank frame 2 using heated element welding, by melting the plastic of the tank frame 2 and pressing it onto the fabric of the filter cloth 6. The tank frame 2 provides a surface for this purpose: a first projection 4, which projects inwards here, and a second projection 5, which projects outwards, for welding to the cover film 7, so that the tank frame has a roughly Z-shaped cross-section.

[0023] When the freeze-drying container 1 is placed in a freezer, the cover film 7 comes into close contact with a heat-absorbing surface and can therefore dissipate the heat particularly effectively. Moisture can escape from the freeze-drying container 1 through the filter cloth 6.

[0024] To enable the most effective temperature measurement and to be able to regulate the cooling process accordingly, the freeze-drying container 1 is provided with a sensor sleeve 8 positioned centrally in the freeze-drying container 1, into which a temperature sensor can be inserted. This allows the temperature sensor to measure the temperature in the core of the product, so that the freeze-drying process can be carried out as accurately as possible. The sensor sleeve 8 is also either welded directly to the filter cloth 6, as shown in the Figure 3shown, or welded to a web 11, which is spanned in a cross shape between the edges of the first projection 4. The web 11, in turn, is then welded to the filter cloth 6. It is also possible to pass the sensor sleeve 8 through a through-opening of the web 11 and / or the filter cloth, so that the welds 13 can be arranged differently but have the same effect.

[0025] The sensor sleeve 8 can be made of polypropylene and have a metallic contact surface 10, so that the temperature sensor gets a good heat-conducting connection to the interior of the freeze-drying container 1 by contacting the contact surface 10. On the back of the sensor sleeve 8 is located, as in Figure 4 shown, a screw connection 12 with a tank thread, which serves to secure and hold the temperature sensor at a depth.

[0026] The above description describes a freeze-drying container with which temperature measurement can be carried out as close as possible to the product, but which is nevertheless sealed liquid-tight.

Claims

1. A freeze-drying tray, comprising a tray frame (2) having a sealable access opening (3) and a circumferential wall, which on a free edge has a first projection (4), on which a filter cloth (6) is circumferentially affixed, characterized in that the filter cloth (6) has a passage opening, through which a measuring sensor sleeve (8) is passed or on which it rests, wherein the measuring sensor sleeve (8) has a connecting edge (9), which surrounds an entrance opening for the insertion of a temperature sensor, and the filter cloth (6) is sealingly fused and pressed along its outer edge with the tray frame (2) and around the passage opening with the adjoining material of the measuring sensor sleeve (8) in each case using heated tool welding.

2. The freeze-drying tray according to Claim 1, characterized in that opposing edges of the first projection (4) are connected to each other via at least one transverse bar (11), preferably in a cruciform shape, which for their part have a passage opening, which corresponds to the passage opening of the filter cloth (6) and through which the measuring sensor sleeve (8) is passed or on which it rests in a sealing manner.

3. The freeze-drying tray according to one of Claims 1 or 2, characterized in that a screw connection (12) is assigned to the measuring sensor sleeve (8) for a precisely positioned fastening of a temperature sensor that can be inserted through the screw connection (12) into the measuring sensor sleeve (8).

4. The freeze-drying tray according to Claim 3, characterized in that the screw connection (12) is a Panzergewinde (steel conduit thread).

5. The freeze-drying tray according to one of the preceding claims, characterized in that the tray frame (2) and / or the measuring sensor sleeve (8) are produced in each case from polyethylene, polypropylene or polyester.

6. The freeze-drying tray according to one of the preceding claims, characterized in that the measuring sensor sleeve (8) has a metallic contact surface (10) on its free end.

7. The freeze-drying tray according to one of the preceding claims, characterized in that the filter cloth (6) is produced from a polytetrafluorethylene membrane, which is laminated on a polytetrafluorethylene carrier.

8. The freeze-drying tray according to one of Claims 1 through 6, characterized in that the filter cloth (6) is made of a polytetrafluorethylene membrane, which is laminated on a carrier made of polyethylene, polypropylene or polyester.

9. The freeze-drying tray according to one of the preceding claims, characterized in that the tray frame (2) has, on its side opposite from the first projection (4), another free edge with a second projection (5), on which a cover film (7) is affixed, preferably welded on.

10. The freeze-drying tray according to Claim 9, characterized in that the cover film (7) is produced from the same material as the tray frame (2).

11. The freeze-drying tray according to one of Claims 1 through 8, characterized in that the tray frame (2) forms a closed cover on its side opposite from the first projection (4).