Annealing module for stretched thermoplastic tape production plant

Abstract

The invention relates to an annealing module (1) for a device for producing stretched thermoplastic tapes (20), comprising a housing (2) having an inlet (4) and an outlet (5) for the passage of a plastic tape (20) to be treated through an inner space (3) of the housing (2). In the interior space (3), a plurality of rotary drive rollers (6-11) are arranged axially parallel to one another and are at least partially surrounded by a plastic strip (20). The annealing module (1) is equipped with a heating device for uniformly heating the interior space (3) to a temperature of at least 70% of the melting temperature of the plastic strip (20) to be treated and for heating the interior space (3) to a temperature that is at most 5% higher than the melting temperature of the plastic strip (20) to be treated. The rollers (6-11) are driven at a rotational speed such that the dwell time of the strip in the annealing module according to the path through the annealing module (1) is at most 10 seconds.

Description

Technical Field

[0001] The invention relates to an annealing module of a plant for producing stretched thermoplastic tapes. Background Art

[0002] The production of stretched thermoplastic tapes involves melting plastic, which is usually in granular form. The molten plastic material is extruded through an extrusion die to form a film web, which is then cooled, for example in a water bath or by cooling rollers, and cut longitudinally into tapes in a subsequent processing step. This is usually achieved by moving the film web over a number of knives arranged side by side. After cutting, the plastic tape is stretched in a hot air oven to a multiple of its original length in order to increase its tensile strength and E modulus, thereby reducing its width to a fraction of its original width. In order to reduce the residual shrinkage of the tape during further processing, it is necessary to subject it to a fixing process known as annealing.

[0003] During the annealing process, the tape is heated to a temperature above its glass transition temperature. This is usually achieved by passing the tape through heated rollers (also called godets), as described in patent application WO 2019 / 034488, whereby the plastic tape in the inner space between the godets is not exposed to the same conditions as the contact points of the godets and is therefore heated unevenly. Specifically, these tapes are polyamide filaments produced by spinnerets. The glass transition temperature of polyamide is typically 60-75°C. The shell surface of the godet is heated to a surface temperature of 130-190°C, thus well above the glass transition temperature of the polyamide.

[0004] The effects of uneven temperatures on the plastic strip during annealing can lead to undesirable deformations of the strip. To prevent this, patent specification US 6472066 discloses a process in which short-cut PET fibers obtained by melt spinning are produced with low residual shrinkage by annealing them uniformly under the pressure of saturated hot water vapor. The saturated water vapor condenses on the fibers. These fibers are then suitable for producing wet-laid nonwovens. The glass transition temperature of PET is about 80° C. The fibers are annealed at a high temperature of at least 165° C. The temperature of the supplied water vapor is therefore much higher than the glass transition temperature of PET. In addition, the supplied water vapor is discharged from the fiber treatment zone into the environment via two steam outlets.

[0005] Treating stretched plastic strips with water vapor to fix them (annealing) is not suitable because the process requires an additional drying step afterward. Such a drying step is not feasible in practice because the strips are wound onto reels at high speed after annealing. As a result, the residence time of the strip in the dryer is unacceptably short or the length of the dryer must be impractically long. Furthermore, the use of water vapor is resource-intensive and costly. Summary of the invention

[0006] The object of the present invention is therefore to provide an annealing module for a plant for producing stretched thermoplastic tapes which ensures uniform heating of the tape to a temperature suitable for annealing within a short period of time and under constant, controllable conditions, while functioning in a resource- and cost-saving manner.

[0007] This object is achieved by providing an annealing module having the features of claim 1. Advantageous embodiments of the invention are set forth in the dependent claims as well as in the description and the drawings.

[0008] The annealing module of the apparatus for producing stretched thermoplastic tapes according to the invention has a housing which defines an interior space, wherein the housing has an inlet and an outlet for the plastic tape to be treated to pass through the interior space. In the interior space, a plurality of rotating driven rollers are arranged on axes parallel to each other and are configured to be at least partially surrounded by the plastic tape. The annealing module is equipped with a heating device, which is configured to uniformly heat the interior space to a temperature of at least 70%, preferably at least 75%, of the melting temperature. The rollers are driven at a rotational speed such that the residence time of the tape in the annealing module is at most 10 seconds, preferably at most 5 seconds, even more preferably at most 3 seconds, depending on the path through the annealing module.

[0009] In a preferred embodiment of the invention, the heating device is further configured to uniformly heat the interior space to a temperature which is at most 5% higher, more preferably at most 3% higher, and most preferably at most the melting temperature of the plastic strip to be treated. In this embodiment, during the treatment of the plastic strip, the interior space is thus kept at a preset operating temperature within a temperature range having a defined minimum temperature and a defined maximum temperature. Brief passage of the plastic strips through an atmosphere in the interior space having a temperature above the melting temperature does not damage the plastic strips, since their residence time in the interior space of the annealing module is very short.

[0010] Document EP 2757125 A1 describes the production of a microporous membrane based on propylene resin, in which the resin is first extruded into a film, then stretched in two stages and then treated in an annealing furnace. The film passes through the annealing furnace in a zigzag manner around a guide roller. The film is heated for a predetermined time, then it is transported out of the furnace and continuously wound on a lap roller. An exemplary embodiment is explained in which the film is annealed for 10 minutes to a surface temperature of 140°C. No tension is applied to the film. The document does not contain any information about how the film is heated in the annealing furnace. Very long annealing times are not suitable for the production of a stretched thermoplastic tape according to the invention because it destroys the molecular structure of the tape produced under tension. As described above, according to the invention, even if the temperature of the internal space of the annealing module is higher than the melting temperature of the tape, a very short residence time of up to 10 seconds of the tape in the annealing module will not damage the tape. However, if the temperature of the internal space of the annealing module is 70% of the melting temperature of the tape, a residence time of several minutes will also damage the tape and make it unusable. The system of EP 2757125 A1 is also completely unsuitable for the production of stretched plastic strips simply because of its slow operation. Stretched thermoplastic strips are produced and annealed at a speed of several hundred meters per minute. This is several orders of magnitude faster than the speed that can be achieved by the system of EP 2757125 A1.

[0011] In order to keep the energy consumption of the annealing module low, the housing can be thermally insulated.

[0012] In a preferred embodiment of the annealing module according to the invention, the heating device comprises a hot air flow introduced into the interior space, wherein the hot air flow is preferably formed by at least one hot air blower arranged outside the housing, the outlet of which leads to the interior space. In this embodiment, the entire interior space can be quickly heated to the required temperature, and the temperature regulation will soon be apparent throughout the interior space. The hot air flow is preferably configured as a recirculating air flow, because it is supplied to the interior space and is extracted as a return flow at another point in the interior space and returned to the inlet of the hot air blower. This makes the operation of the annealing module particularly energy-efficient.

[0013] In a further embodiment of the annealing module according to the invention, the heating device comprises a heating device arranged in the inner space of the housing, preferably an electric or inductive heating element or a heating element through which a heating fluid flows.

[0014] In another embodiment of the annealing module, the rollers have heating elements, which preferably comprise electrical or inductive heating elements or heating elements through which a heating fluid flows. In this embodiment, the rollers can be heated to a temperature range which corresponds approximately to the temperature existing in the interior of the annealing module, so that the plastic strip is exposed to as little temperature difference as possible or to no temperature difference at all during the annealing process. Furthermore, this embodiment allows the interior of the annealing module to be heated more quickly, in particular when using a hot gas flow as the heating means.

[0015] Preferably, the rotating drive roller is arranged such that the surface of its housing is wrapped by the plastic strip over a wrap angle of less than 360°, but preferably at least 150°.

[0016] In order to simplify the control of the rotational speed of the rollers, another embodiment of the annealing module according to the invention provides that at least some of the rotating driven rollers are combined to form at least two roller groups, wherein each roller in each roller group has the same shell surface circumferential speed, wherein, viewed from the conveying direction of the plastic strip, the roller shell surface circumferential speed of each roller group is lower than the roller shell surface circumferential speed of the roller group adjacent to it in the direction opposite to the conveying direction.

[0017] Optionally, the annealing module can have at least one rotationally driven cooling roller, which is arranged downward from the outlet of the housing, as seen in the conveying direction of the plastic strip. The cooling roller can run at a different shell surface peripheral speed than a drive roller arranged in the housing of the annealing module.

[0018] In order to precisely adjust and perform the annealing process, it is useful to provide a control module to set and control the rotation speed of the rollers and at least one other parameter selected from the internal space temperature and / or the heating temperature of the heating device.

[0019] If the atmosphere in the internal space is an air atmosphere and any hot gas introduced into the internal space is hot air, the design of the annealing module is simplified. In this case, no complex design is required to strictly separate the process gas from the ambient atmosphere. In addition, if the annealing module is configured so that the pressure in the internal space is substantially the same as the pressure in the atmosphere surrounding the annealing module, the withstand voltage differential insulation and sealing can be omitted.

[0020] In a preferred embodiment, the annealing module is suitable for processing plastic strips made of polyester materials, PET (polyethylene terephthalate) or polyolefins, in particular PP (polypropylene), HDPE (high-density polyethylene), LLDPE (linear low-density polyethylene). This means that the annealing module can be operated in a temperature range optimized for annealing the above-mentioned plastic materials. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The present invention will be explained in more detail below by means of exemplary embodiments with reference to the accompanying drawings. In the drawings:

[0022] Figure 1 is a perspective view of an embodiment of an annealing module having an open interior space according to the present invention;

[0023] Figure 2 is a side view of an annealing module having an open interior space; and

[0024] Figure 3 is a side view of an annealing module having a closed interior space. DETAILED DESCRIPTION

[0025] An embodiment of an annealing module 1 according to the invention will now be explained in detail with reference to the accompanying drawings. The annealing module 1 is used for annealing a stretched thermoplastic strip 20 .

[0026] The stretched thermoplastic tape 20 is produced by melting a plastic material which is usually in the form of granules. The molten plastic material is extruded through an extrusion die to form a film web which is cooled by cooling rollers, a water bath, etc. and then cut longitudinally into strips by passing the film web through a plurality of adjacent knives. In a hot air oven the strip is stretched to a multiple of its original length under tensile stress, thereby reducing its width to a fraction of the original width, i.e., a so-called stretched plastic tape 20 having a multiple of the tensile strength and E modulus of the original cut strip. The production of plastic tapes up to the annealing process is prior art known to those skilled in the art and therefore does not need to be described in detail. When the stretched tape is reheated after cooling, for example by a coating process, residual shrinkage occurs. In order to reduce this undesirable residual shrinkage, it is useful to subject the plastic tape to a fixing process called annealing, for which an annealing module 1 is used.

[0027] The annealing module 1 is part of an apparatus for producing stretched thermoplastic tapes. The annealing module 1 has a housing 2 defining an inner space 3. The housing 2 is provided with a heat-insulating wall to insulate the inner space 3 from the ambient temperature. The housing 2 has an inlet 4 and an outlet 5 for passing the plastic tape 20 to be treated through the inner space 3. The inlet 4 and the outlet 5 are configured as slits and have an inlet sealing lip 4a and an outlet sealing lip 5a, respectively, to keep the clear width of the inlet 4 and the inlet 5 as small as possible, thereby minimizing heat losses in the inner space 3. In the inner space 3, there are six rotating drive rollers 6, 7, 8, 9, 10, 11, so-called godet rollers, arranged on axes parallel to each other and arranged in such a way that they are at least partially wrapped by the plastic tape 20. Preferably, the rotating drive rollers are arranged in such a way that their shell surfaces are wrapped by the plastic tape 20 at a wrap angle of less than 360° but preferably at least 150°.

[0028] In the embodiment shown, the rollers 6, 7, 8, 9, 10, 11 are not heated but absorb the temperature prevailing in the interior space 3 on their shell surfaces. Alternatively, however, at least some of the rollers 6, 7, 8, 9, 10, 11 may be equipped with electrical or inductive heating elements or heating elements through which a heating fluid flows or other heating elements.

[0029] The first two rotating driven rollers 6, 7, viewed in the conveying direction T of the plastic strip 20, are combined to form a first roller group, whose rotation is controlled so that their shell surfaces have the same peripheral speed V1. The next two rotating driven rollers 8, 9 arranged downstream of the rollers 6, 7 are combined to form a second roller group, whose rotation is controlled so that their shell surfaces have the same peripheral speed V2. The last two rotating driven rollers 10, 11 arranged downstream of the rollers 8, 9 are combined to form a third roller group, whose rotation is controlled so that their shell surfaces have the same peripheral speed V3. The peripheral speed V1 of the first roller group 6, 7 is higher than the peripheral speed V2 of the second roller group 8, 9. The peripheral speed V2 of the second roller group 8, 9 is higher than the peripheral speed V3 of the third roller group 10, 11. This will form a relaxation zone between the first, second and third roller groups, more precisely, in the transition area between the rotating driven rollers 7, 8 and 9, 10, in which the plastic strip 20 can relax.

[0030] The rollers 6-11 are driven at a rotational speed such that the residence time of the strip 20 in the annealing module 1 is at most 10 seconds, preferably at most 5 seconds, even more preferably at most 3 seconds, according to the path through the annealing module 1. The length of the strip 20 in the annealing module 1, i.e. the length of its path within the annealing module 1, is, for example, between 4.35 m and 7.65 m. The strip 20 can pass through the annealing module 1 at a travel speed, for example, between 150 m / min and 650 m / min, resulting in a residence time in the annealing module 1 of 0.4 s to 3.06 s.

[0031] The annealing module 1 is equipped with heating means for uniformly heating the interior space 3 to a temperature of at least 70%, preferably at least 75%, of the melting temperature of the plastic strip to be treated. Furthermore, the heating means are controlled in such a way that they ensure uniform heating of the interior space to a temperature of at most 5%, preferably at most 3%, more preferably up to the melting temperature of the plastic strip 20 to be treated. In the illustrated embodiment of the annealing module 1, the heating means are implemented by a hot air blower 14, which is arranged outside the housing 2 and generates a hot air flow 15, which is blown into the interior space 3 through the outlet of the hot air blower 14 which is connected to the interior space 3. The temperature of the hot air flow 15 is measured and the hot air blower 14 is controlled so that the hot air flow 15 has the (adjustable) desired operating temperature. The hot gas flow 15 is preferably guided as a circulating gas flow through the interior space 3 of the housing 2, because the hot gas flow 15 is blown into the interior space 3 by the hot gas blower 14, and the return flow 15a is extracted from the interior space at another point in the interior space 3 and returned to the hot gas blower 14. In this way, the annealing module 1 can be operated in a very energy-saving manner.

[0032] In alternative embodiments of the annealing module 1 , the heating device may be configured as a heating element, preferably an electric or inductive heating element, arranged in the inner space 3 , or a heating element through which a heating fluid flows.

[0033] As mentioned above, the annealing module 1 is configured to heat the inner space 3 to a temperature of at least 70%, preferably at least 75%, of the melting temperature of the plastic strip 20 to be treated. At the same time, the heating device is operated in such a way as to ensure that the inner space is uniformly heated to a temperature of at most 5%, preferably at most 3%, more preferably up to the melting temperature of the plastic strip 20 to be treated.

[0034] The annealing module 1 may be specially configured for the type of plastic of the plastic strip 20. Preferably, the annealing module 1 may be configured for processing a plastic strip 20 made of polyester material, in particular PET, or polyolefins, in particular PP, HDPE or LLDPE.

[0035] Every plastic material is characterized by its melting temperature. Although the melting temperature may vary slightly depending on the manufacturer and other properties imparted to the plastic, it can be found on the data sheet of the respective plastic material.

[0036] The typical melting temperature of polypropylene (PP) is 160° C. In order to configure the annealing module 1 for PP, the heating device is respectively set to heat the inner space 3 to at least 112° C., which is 70% of the melting temperature of 160° C., or to keep the temperature of the inner space 3 at this level. Preferably, the heating device is respectively set to heat the inner space 3 to at least 120° C. (which is 75% of the melting temperature) or to keep the temperature at this level. At the same time, the heating device is respectively set to heat the inner space 3 to a maximum of 168° C. (which is 5% higher than the melting temperature), preferably a maximum of 164.8° C. (which is 3% higher than the melting temperature), more preferably a maximum of 160° C. (which is the melting temperature), or to keep the temperature of the inner space 3 at this level. Therefore, for PP, an operating temperature range between 112° C. and 168° C. is established, or in the most preferred embodiment, an operating temperature range between 120° C. and 160° C. is established. Within this operating temperature range, the operating temperature is additionally selected according to other characteristics of the plastic material. The annealing module 1 controls the heating device in such a way that the selected operating temperature in the inner space 3 is maintained very accurately (ie with a maximum fluctuation of ±2° C.).

[0037] The typical melting temperature of polyethylene terephthalate (PET) is 260° C. In order to configure the annealing module 1 for PET, the heating device is respectively set to heat the inner space 3 to at least 182° C., which is 70% of the melting temperature of 260° C., or to keep the temperature of the inner space 3 at this level. Preferably, the heating device is respectively set to heat the inner space 3 to at least 195° C. (which is 75% of the melting temperature) or to keep the temperature at this level. At the same time, the heating device is respectively set to heat the inner space 3 to a maximum of 273° C. (which is 5% higher than the melting temperature), preferably a maximum of 267.8° C. (which is 3% higher than the melting temperature), more preferably a maximum of 260° C. (which is the melting temperature), or to keep the temperature in the inner space 3 at this level.

[0038] The typical melting temperature of high-density polyethylene (HDPE or PE-HD) is 135° C. In order to configure the annealing module for HDPE, the heating device is respectively set to heat the inner space 3 to at least 94.5° C., which is 70% of the melting temperature of 135° C., or to keep the temperature in the inner space 3 at this level. Preferably, the heating device is respectively set to heat the inner space 3 to at least 101.25° C. (which is 75% of the melting temperature) or to keep the temperature at this level. At the same time, the heating device is respectively set to heat the inner space 3 to a maximum of 141.75° C. (which is 5% higher than the melting temperature), preferably a maximum of 139.05° C. (which is 3% higher than the melting temperature), more preferably a maximum of 135° C. (which is the melting temperature), or to keep the temperature in the inner space 3 at this level.

[0039] The typical melting temperature of linear low-density polyethylene (LLDPE or PE-LLD) is 110° C. In order to configure the annealing module for LLDPE, the heating device is respectively set to heat the inner space 3 to at least 77° C., which is 70% of the melting temperature of 110° C., or to keep the temperature in the inner space 3 at this level. Preferably, the heating device is respectively set to heat the inner space 3 to at least 82.5° C. (which is 75% of the melting temperature) or to keep the temperature at this level. At the same time, the heating device is respectively set to heat the inner space 3 to a maximum of 115.5° C. (which is 5% higher than the melting temperature), preferably a maximum of 113.3° C. (which is 3% higher than the melting temperature), more preferably a maximum of 110° C. (which is the melting temperature), or to keep the temperature in the inner space 3 at this level.

[0040] In the embodiment shown, the annealing module 1 is configured such that the atmosphere in the inner space 3 is an air atmosphere and the hot gas flow 15 supplied to the inner space 3 is hot air. Furthermore, the pressure in the inner space 3 is substantially the same as the pressure in the atmosphere surrounding the annealing module 1. It is preferred to use an air atmosphere and ambient pressure in the inner space 3, simply because it means that the inner space 3 does not need to be sealed off from the environment, in particular the inlet 4 and the outlet 5 do not need to be airtight.

[0041] The annealing module 1 is equipped downstream of the outlet 5 of the housing 2 , viewed in the conveying direction T of the plastic strip 20 , with two rotationally driven cooling rollers 12 , 13 , which cool the plastic strip 20 to a temperature that allows its immediate further processing, for example winding onto a reel.

[0042] The annealing module 1 is controlled by an electronic control module 16 which directly or indirectly controls the temperature in the inner space 3 , the heating temperature of the heating device, in particular the temperature of the hot gas flow 15 , and the rotation speed of the rollers 6 - 13 .

[0043] Figure 3 The annealing module 1 is shown in the closed state, with the housing door 17 folded down to seal the inner space 3. The housing door 17 is equipped with an inspection window 18, through which the operator can monitor the correct path of the plastic strip 20. In addition, the housing door has a transparent cover 19 made of glass or plastic, which allows the cooling rollers 12, 13 to be seen, but prevents access to the cooling rollers for safety reasons.

[0044] exist Figure 1 and Figure 2 In the figures, the annealing module is shown in an open state. For the sake of clarity, the housing door 17 is omitted in these figures.

[0045] List of reference numerals:

[0046] 1 Annealing module

[0047] 2 Housing

[0048] 3. Internal Space

[0049] 4 Entrance

[0050] 4a Inlet sealing lip

[0051] 5. Exit

[0052] 5a Outlet sealing lip

[0053] 6, 7, 8, 9, 10, 11 rotating drive rollers

[0054] 12, 13 cooling roller

[0055] 14 Hot air blower

[0056] 15 Thermals

[0057] 15a Reflow

[0058] 16 Control Module

[0059] 17 Shell door

[0060] 18 Inspection window

[0061] 19 Transparent cover

[0062] 20 Plastic tape

[0063] T Plastic belt conveying direction

[0064] V1 Circumferential speed of the first set of rollers

[0065] V2 Circumferential speed of the second set of rollers

[0066] V3 Circumferential speed of the third set of rollers

Claims

1. An annealing module (1) of a device for producing stretched thermoplastic strips, the annealing module (1) having a housing (2) defining an inner space (3), wherein the housing (2) has an inlet (4) and an outlet (5) for a plastic strip (20) to be treated to pass through the inner space (3), wherein: In the inner space (3), a plurality of rotating drive rollers (6-11) are arranged on axes parallel to each other and are configured to be at least partially surrounded by the plastic strip (20), characterized in that the annealing module (1) is equipped with a heating device, which is used to uniformly heat the inner space (3) to a temperature of at least 70%, preferably at least 75% of the melting temperature of the plastic strip (20) to be treated, and the rollers (6-11) are driven at a rotation speed so that the strip, depending on the path through the annealing module (1), has a residence time in the annealing module of at most 10 seconds, preferably at most 5 seconds, and more preferably at most 3 seconds.

2. The annealing module according to claim 1, characterized in that: The heating device is configured to uniformly heat the inner space (3) to a temperature that is at most 5% higher than the melting temperature of the plastic strip (20) to be treated, preferably at most 3% higher than the melting temperature, and most preferably at most the melting temperature of the plastic strip (20) to be treated.

3. The annealing module according to claim 1 or 2, characterized in that: The housing (2) is heat-insulating.

4. Annealing module according to any one of the preceding claims, characterized in that The heating device comprises a hot air flow (15) introduced into the inner space, wherein the hot air flow (15) is preferably formed by at least one hot air blower (14) arranged outside the housing (2), and the outlet of the hot air blower is connected to the inner area (3).

5. The annealing module according to claim 4, characterized in that: The hot air flow (15) is configured as a recirculating air flow, as it is supplied to the interior space 3 and is extracted at another point of the interior space as a return flow (15a) and returned to the inlet of the hot air blower (14).

6. Annealing module according to any one of the preceding claims, characterized in that The heating device comprises a heating element arranged in the interior space (3) of the housing (2), preferably an electric or inductive heating element or a heating element through which a heating fluid flows.

7. Annealing module according to any one of the preceding claims, characterized in that The rollers (6-11) have heating elements, wherein the heating elements preferably comprise electrical or inductive heating elements or heating elements through which a heating fluid flows.

8. Annealing module according to any one of the preceding claims, characterized in that The rotating drive rollers (6-11) are arranged so that their shell surfaces are wrapped by the plastic strip (20) at a wrapping angle of less than 360° but preferably at least 150°.

9. Annealing module according to any one of the preceding claims, characterized in that At least some of the rotating drive rollers (6-11) are combined to form at least two roller groups (6-7; 8-9; 10-11), wherein the rollers (6-7; 8-9; 10-11) in each roller group have the same shell surface circumferential speed, wherein, viewed from the conveying direction (T) of the plastic belt (20), the roller shell surface circumferential speed (V3; V2; V1) of each roller group (10-11; 8-9; 6-7) is lower than the roller shell surface circumferential speed of the roller group (6-7; 8-9; 10-11) adjacent to it in the direction opposite to the conveying direction (T).

10. Annealing module according to any one of the preceding claims, characterized in that At least one rotationally driven cooling roller (12, 13) is arranged downwardly from the outlet (5) of the housing (2), viewed in the conveying direction (T) of the plastic strip (20).

11. Annealing module according to any one of the preceding claims, characterized in that A control module (16) is provided for setting and controlling the rotation speed of the roller and at least one other parameter selected from the internal temperature and / or the heating temperature of the heating device.

12. Annealing module according to any one of the preceding claims, characterized in that The atmosphere in the interior space (3) is an air atmosphere, and optionally, any hot gas introduced into the interior space is hot air.

13. Annealing module according to any one of the preceding claims, characterized in that The pressure in the inner space (3) is substantially the same as the pressure in the atmosphere surrounding the annealing module (1).

14. Annealing module according to any one of the preceding claims, characterized in that It is suitable for processing plastic strips (20) made of polyester materials, in particular PET, or polyolefins, in particular PP, HDPE, LLDPE.

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