Annealing module of a device for producing stretched thermoplastic tapes

Abstract

The invention relates to an annealing module (1) of a device for producing stretched thermoplastic tapes (20), said annealing module comprising a housing (2) having an inlet (4) and an outlet (5) for the passage of the plastic tapes (20) to be treated through the interior (3) of the housing (2). In the interior (3), a plurality of rotationally driven rollers (6-11) are arranged axially parallel to one another, and the plastic strips (20) are at least partially wrapped around said rollers. The annealing module (1) is equipped with heating means for uniformly heating the interior (3) to a temperature which is at least 70% of the melting temperature of the plastic tapes (20) to be treated, and for heating the interior (3) to a temperature of at most 5% above the melting temperature of the plastic tapes (20) to be treated. The rollers (6-11) are driven at such a rotational speed that the tapes have a maximum residence time of 10 seconds in the annealing module, depending on their route through the annealing module (1).

Description

[0001] Annealing module of a device for producing stretched thermoplastic ribbons

[0002] The invention relates to an annealing module of a device for producing stretched thermoplastic ribbons.

[0003] In the production of stretched thermoplastic tapes, plastic, usually in the form of granules, is melted. The molten plastic material is forced through an extrusion die, creating a film web. This is then cooled, for example, in a water bath or using a cooled roller. In a subsequent processing step, the film web is cut lengthwise into tapes. This is usually done by moving the film web over a large number of knives arranged side by side. After the plastic tapes have been cut, they are stretched in a hot-air oven to several times their original length to increase their tear strength and elastic modulus, thereby reducing their width to a fraction of its original width.In order to reduce the residual shrinkage during further processing of the ribbons, it is necessary to subject them to a fixation process, the so-called annealing.

[0004] During annealing, the ribbons are heated to a temperature above their glass transition temperature. This is typically done by passing the ribbons over heated rollers, also known as godets, as described in patent application WO 2019 / 034488. The plastic ribbons in the space between the godets are not exposed to the same conditions as at the contact points with the godets and are therefore heated unevenly. Specifically, ribbons are polyamide threads produced using spinnerets. Polyamide has a glass transition temperature of typically 60-75°C. The outer surfaces of the godets are heated to a surface temperature of 130-190°C, well above the glass transition temperature of polyamide.

[0005] Uneven temperature exposure of the plastic ribbons during annealing can lead to undesired deformation of the ribbons. To prevent this, patent US 6472066 discloses a process in which short-cut, melt-spun PET fibers with low residual shrinkage are produced. Annealing occurs by uniformly heating the fibers under pressure using saturated hot steam. The saturated steam condenses on the fibers. These fibers are then suitable for the production of wet-laid nonwovens. The glass transition temperature of PET is 80°C. The fibers are annealed at a high temperature of at least 165°C. The supplied steam thus has a temperature well above the glass transition temperature of PET. In addition, the supplied steam escapes from the fiber treatment zone to the environment through two steam outlets.

[0006] Treating stretched plastic ribbons with steam to fix them (annealing) is unsuitable, as this process would require an additional drying step. This drying step is not feasible in practice because the ribbons are wound onto reels at high speed after annealing. Therefore, the ribbons would have an unusably short residence time in a drying system, or the drying system would have to be unrealistically long. Furthermore, the use of steam is resource-intensive and expensive.

[0007] It is therefore the object of the present invention to provide an annealing module of a device for producing stretched thermoplastic ribbons, which ensures uniform heating of the ribbons to a temperature suitable for annealing and the presence of constant, controllable conditions in a short time while the ribbons are passing through the treatment stations, and which at the same time functions in a resource- and cost-saving manner.

[0008] 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.

[0009] The annealing module according to the invention of a device for producing stretched thermoplastic ribbons has a housing defining an interior space, wherein the housing has an inlet and an outlet for passing the plastic ribbons to be treated through the interior space. Within the interior space, several rotating rollers are arranged axially parallel to one another and are designed to be at least partially wrapped by the plastic ribbons. The annealing module is equipped with heating means designed to uniformly heat the interior space to a temperature that is at least 70%, preferably at least 75%, of the melting temperature.The rollers are driven at a rotational speed such that the ribbons, depending on their path through the annealing module, have a residence time in the annealing module of a maximum of 10 seconds, preferably a maximum of 5 seconds, even more preferably a maximum of 3 seconds.

[0010] In a preferred embodiment of the invention, the heating means are also designed to uniformly heat the interior to a temperature of a maximum of 5% above the melting temperature, more preferably a maximum of 3% above the melting temperature, most preferably a maximum of the melting temperature of the plastic ribbons to be treated. In this embodiment, the interior is thus maintained at a preset working temperature during the treatment of the plastic ribbons, which lies within a temperature range comprising the defined minimum temperature and the defined maximum temperature. Briefly passing the plastic ribbons through an atmosphere in the interior whose temperature is above the melting temperature does not damage the plastic ribbons, since their residence time in the interior of the annealing module is very short.

[0011] Document EP 2757125 A1 describes the production of a microporous film based on a propylene resin. The resin is first extruded into a film, which is then stretched in two stages and subsequently treated in an annealing oven. The film is guided through the annealing oven in a zigzag pattern around guide rollers. The film is heated for a predetermined time and then conveyed out of the oven and continuously wound onto a winding roller. An embodiment is explained in which the film is annealed for 10 minutes so that its surface temperature reaches 140°C. No tensile force is exerted on the film. The document contains no information on how the film is heated in the annealing oven. The very long annealing time would be unsuitable for the inventive production of stretched thermoplastic ribbons, as it would damage the molecular structure of the ribbons produced under tension.As mentioned above, it has been shown according to the invention that a very short residence time of the ribbons in the annealing module of a maximum of 10 seconds does not damage the ribbons, even if the temperature inside the annealing module is above the ribbons' melting temperature. However, a residence time of several minutes would damage the ribbons and render them unusable even if the temperature inside the annealing module is 70% of the ribbons' melting temperature. The system of EP 2757125 A1 would be completely unsuitable for producing stretched plastic ribbons, if only because of its slow operation. Stretched thermoplastic ribbons are produced and annealed at speeds of several hundred meters per minute. This is several orders of magnitude faster than the system of EP 2757125 A1 is capable of.

[0012] In order to keep the energy consumption of the annealing module low, the housing can be thermally insulated.

[0013] In a preferred embodiment of the annealing module according to the invention, the heating means comprise a hot gas stream guided into the interior, wherein the hot gas stream is preferably formed by at least one hot gas blower arranged outside the housing, the outlet of which leads into the interior. With this embodiment, the entire interior can be quickly heated to the intended temperature, and temperature adjustments are quickly noticeable throughout the entire interior. The hot gas stream is preferably designed as a recirculating air stream in that it is fed into the interior and extracted as a return stream at another location in the interior and returned to the inlet of the hot gas blower. This enables particularly energy-efficient operation of the annealing module.

[0014] In a further embodiment of the annealing module according to the invention, the heating means comprise heating elements arranged in the interior of the housing, preferably electrical or inductive or heating fluid-flowing heating elements.

[0015] In a further embodiment of the annealing module, the rollers have heating elements, wherein the heating elements preferably comprise electrical or inductive heating elements or heating elements through which a heating fluid flows. This embodiment makes it possible to heat the rollers to a temperature range that approximately corresponds to the temperature prevailing in the interior of the annealing module, so that the plastic ribbons are exposed to minimal or no temperature differences during annealing. Furthermore, this embodiment allows for faster heating of the interior of the annealing module, especially when a hot gas stream is used as the heating medium.

[0016] Preferably, the rotatingly driven rollers are arranged such that the surfaces of their shells are wrapped by the plastic ribbons at a wrap angle of less than 360°, but preferably of at least 150°. In order to simplify the control of the rotational speeds of the rollers, a further embodiment of the annealing module according to the invention provides that at least some of the rotatingly driven rollers are combined to form at least two roller groups, wherein the rollers of a roller group each have the same circumferential speeds of their shell surfaces, wherein - viewed in the transport direction of the plastic ribbons - each roller group has a lower circumferential speed of the shell surfaces of the rollers than the adjacent roller group opposite the transport direction.

[0017] Optionally, the annealing module can have at least one rotating cooling roller, which is arranged downstream of the housing outlet, as seen in the transport direction of the plastic ribbons. This cooling roller can be operated at a different peripheral speed of its shell surface than the driven rollers arranged in the housing of the annealing module.

[0018] For precise adjustment and execution of the annealing process, it is expedient to provide a control module for adjusting and regulating the rotational speeds of the rollers and at least one further parameter selected from the interior temperature and / or the heating temperature of the heating means.

[0019] A simplified design of the annealing module is achieved when the atmosphere in the interior is air and any hot gas supplied into the interior is hot air. In this case, complex structures for the strict separation of process gas from the ambient atmosphere are not required. Furthermore, pressure-difference-resistant insulation and seals can be dispensed with if the annealing module is configured so that the pressure in the interior is essentially the same as in the atmosphere surrounding the annealing module.

[0020] In a preferred embodiment, the annealing module is adapted for the treatment of plastic ribbons made of a polyester material, PET (polyethylene terephthalate), or a polyolefin, in particular PP (polypropylene), HOPE (high-density polyethylene), or LLDPE (linear low-density polyethylene). This means that the annealing module can be operated in the temperature ranges optimized for the annealing of these plastics.

[0021] The invention is explained in more detail below using exemplary embodiments with reference to the drawings. The drawings show: Fig. 1 shows an embodiment of the annealing module according to the invention with an open interior in a perspective view;

[0022] Fig. 2 shows the annealing module in a side view with the interior open; and Fig. 3 shows the annealing module in a side view with the interior closed.

[0023] With reference to the figures, an embodiment of the annealing module 1 according to the invention will now be explained in detail. This annealing module 1 serves to carry out an annealing process on stretched thermoplastic ribbons 20.

[0024] The stretched thermoplastic ribbons 20 are manufactured by melting plastic, which is usually in the form of granules. The molten plastic material is forced through an extrusion die, forming a film web. This film web is cooled by chilled rollers, a water bath, etc., and then cut lengthwise into strips by passing the film web over a plurality of adjacent knives. The strips are stretched in a hot-air oven under the application of tensile stress to several times their original length, thereby reducing their width to a fraction of the original width. These strips are referred to as stretched plastic ribbons 20 and have several times the tear strength and Young's modulus of the originally cut strips.The production of the plastic ribbons up to the annealing process is well known to those skilled in the art and therefore requires no further explanation. If the stretched ribbons are reheated after cooling, e.g., through a coating process, residual shrinkage occurs. To reduce this undesirable residual shrinkage, it is advisable to subject the plastic ribbons to a fixation process known as annealing, for which Annealing Module 1 is used.

[0025] The annealing module 1 is part of a device for producing stretched thermoplastic ribbons. The annealing module 1 has a housing 2 defining an interior space 3. The housing 2 is provided with heat-insulating walls to insulate the interior space 3 from ambient temperatures. The housing 2 has an inlet 4 and an outlet 5 for passing the plastic ribbons 20 to be treated through the interior space 3. The inlet 4 and the outlet 5 are slot-shaped and have an inlet sealing lip 4a and an outlet sealing lip 5a, respectively, in order to keep the clear width of the inlet 4 and the outlet 5 as small as possible and thus minimize heat losses in the interior space 3. In the interior space 3, six rotating driven rollers 6, 7, 8, 9, 10, 11, so-called godets, are arranged axially parallel to one another and arranged in such a way that they are at least partially wrapped around by the plastic strips 20.Preferably, the rotating driven rollers are arranged such that their outer surfaces are wrapped by the plastic strips 20 at a wrap angle of less than 360°, but preferably of at least 150°.

[0026] In the illustrated embodiment, the rollers 6, 7, 8, 9, 10, 11 are not heated, but absorb the temperature prevailing in the interior 3 on their shell surfaces. Alternatively, however, it is also possible to equip at least some of the rollers 6, 7, 8, 9, 10, 11 with electrical, inductive, fluid-flow, or other heating elements.

[0027] The first two rotating driven rollers 6, 7—as seen in the transport direction T of the plastic ribbons 20—are combined to form a first roller group, the rotation of which is controlled such that their outer surfaces each have the same peripheral speed VI. The two next rotating driven rollers 8, 9, arranged downstream of the rollers 6, 7, are combined to form a second roller group, the rotation of which is controlled such that their outer surfaces each 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, the rotation of which is controlled such that their outer surfaces each have the same peripheral speed V3. The peripheral speed VI of the first roller group 6, 7 is greater than the peripheral speed V2 of the second roller group 8, 9.The peripheral speed V2 of the second roller group 8, 9 is greater than the peripheral speed V3 of the third roller group 10, 11. This creates relaxation zones in the transition areas between the first, second and third roller groups, more precisely between the rotating driven rollers 7, 8 and 9, 10, in which the plastic ribbons 20 can relax.

[0028] The rollers 6-11 are driven at a rotational speed such that the ribbons 20, depending on their path through the annealing module 1, have a residence time in the annealing module 1 of a maximum of 10 seconds, preferably a maximum of 5 seconds, more preferably a maximum of 3 seconds. The length of the ribbons 20 in the annealing module 1, i.e. the length of their path in the annealing module 1, is, for example, between 4.35 m and 7.65 m. The ribbons 20 can be moved through the annealing module 1 at a travel speed of, for example, between 150 m / min and 650 m / min, resulting in residence times of 0.4 s to 3.06 s in the annealing module 1.

[0029] The annealing module 1 is equipped with heating means for uniformly heating the interior 3 to a temperature that is at least 70%, preferably at least 75%, of the melting temperature of the plastic ribbons to be treated. The heating means are further controlled such that they ensure uniform heating of the interior to a temperature of a maximum of 5% above the melting temperature, preferably a maximum of 3% above the melting temperature, more preferably a maximum of the melting temperature of the plastic ribbons 20 to be treated. In the illustrated embodiment of the annealing module 1, the heating means are implemented by a hot gas blower 14, which is arranged outside the housing 2 and generates a hot gas stream 15, which is blown into the interior 3 through the outlet of the hot gas blower 14, which communicates with the interior 3.The temperature of the hot gas stream 15 is measured, and the hot gas blower 14 is controlled so that the hot gas stream 15 has a (adjustable) desired operating temperature. The hot gas stream 15 is preferably guided as a recirculating air stream through the interior 3 of the housing 2, in which the hot air stream 15 is blown into the interior 3 by the hot gas blower 14, and a return stream 15a is extracted from the interior at another location in the interior 3 and returned to the hot gas blower 14. In this way, the annealing module 1 can be operated in a very energy-efficient manner.

[0030] In alternative embodiments of the annealing module 1, the heating means can be configured as heating elements arranged in the interior 3, preferably electrical or inductive or heating fluid-flowing heating elements.

[0031] As mentioned above, the annealing module 1 is designed to heat the interior 3 by heating means to a temperature of at least 70%, preferably at least 75%, of the melting temperature of the plastic ribbons 20 to be treated. At the same time, the heating means should be operated such that they ensure uniform heating of the interior to a temperature of a maximum of 5% above the melting temperature, preferably a maximum of 3% above the melting temperature, more preferably a maximum of the melting temperature of the plastic ribbons 20 to be treated.

[0032] Depending on the type of plastic used for the plastic ribbons 20, the annealing module 1 can be configured specifically for that type of plastic. Preferably, the annealing module 1 can be configured for treating plastic ribbons 20 made of a polyester material, in particular PET, or a polyolefin, in particular PP, HOPE, LLDPE.

[0033] A specific property of each plastic is its melting temperature. While the melting temperature varies slightly depending on the manufacturer and other properties imparted to the plastic, it can be found in the data sheet for the respective plastic.

[0034] Polypropylene (PP) has a typical melting temperature of 160 °C. To configure the annealing module 1 for PP, the heating means are set so that they heat the interior space 3 to at least 112 °C, which is 70% of the melting temperature of 160 °C, or to maintain the temperature in the interior space 3 at this temperature. The heating means are preferably set so that they heat the interior space 3 to at least 120 °C (75% of the melting temperature) or to maintain it at this temperature. At the same time, the heating means are set so that they heat the interior space 3 to a maximum of 168 °C (5% above the melting temperature), preferably a maximum of 164.8 °C (3% above the melting temperature), more preferably a maximum of 160 °C (the melting temperature), or to maintain the temperature in the interior space 3 at this temperature. This results in an application temperature range for PP between 112 °C and 168 °C orIn the most preferred embodiment, an application temperature range between 120 °C and 160 °C is used. Within the application temperature range, a working temperature is selected, which depends, among other things, on other properties of the plastic. The annealing module 1 controls the heating means so that the selected working temperature in the interior space 3 is maintained fairly precisely (i.e., with maximum fluctuations of ± 2 °C).

[0035] Polyethylene terephthalate (PET) has a typical melting temperature of 260 °C. To configure the annealing module 1 for PET, the heating means are set to heat the interior space 3 to at least 182 °C, which is 70% of the melting temperature of 260 °C, or to maintain the temperature in the interior space 3 at this temperature. Preferably, the heating means are set to heat the interior space 3 to at least 195 °C (75% of the melting temperature) or to maintain it at this temperature. At the same time, the heating means are set to heat the interior space 3 to a maximum of 273 °C (5% above the melting temperature), preferably a maximum of 267.8 °C (3% above the melting temperature), more preferably a maximum of 260 °C (the melting temperature), or to maintain the temperature in the interior space 3 at this temperature. High-density polyethylene (HDPE or PE-HD) has a typical melting temperature of 135 °C.To configure the annealing module for HDPE, the heating means are set to heat the interior space 3 to at least 94.5 °C, which is 70% of the melting temperature of 135 °C, or to maintain the temperature in the interior space 3 at this temperature. Preferably, the heating means are set to heat the interior space 3 to at least 101.25 °C (75% of the melting temperature) or to maintain it at this temperature. At the same time, the heating means are set to heat the interior space 3 to a maximum of 141.75 °C (5% above the melting temperature), preferably a maximum of 139.05 °C (3% above the melting temperature), more preferably a maximum of 135 °C (the melting temperature), or to maintain the temperature in the interior space 3 at this temperature.

[0036] Linear Low Density Polyethylene (LLDPE or PE-LLD) has a typical melting temperature of 110 °C. To configure the annealing module for LLDPE, the heating means are set to heat the interior space 3 to at least 77 °C, which is 70% of the melting temperature of 110 °C, or to maintain the temperature in the interior space 3 at this temperature. Preferably, the heating means are set to heat the interior space 3 to at least 82.5 °C (75% of the melting temperature) or to maintain this temperature. At the same time, the heating means are set to heat the interior space 3 to a maximum of 115.5 °C (5% above the melting temperature), preferably a maximum of 113.3 °C (3% above the melting temperature), more preferably a maximum of 110 °C (the melting temperature), or to maintain the temperature in the interior space 3 at this temperature.

[0037] In the illustrated embodiment, the annealing module 1 is configured such that the atmosphere in the interior space 3 is an air atmosphere, and the hot gas stream 15 supplied to the interior space 3 is hot air. Furthermore, the pressure in the interior space 3 is essentially the same as in the atmosphere surrounding the annealing module 1. The use of an air atmosphere and ambient pressure in the interior space 3 is preferred simply because it eliminates the need to seal the interior space 3 from the environment, and in particular, the inlet 4 and outlet 5 do not need to be gas-tight.

[0038] The annealing module 1 is equipped - viewed in the transport direction T of the plastic ribbons 20 - downwards from the outlet 5 of the housing 2 with two rotatingly driven cooling rollers 12, 13, with which the plastic ribbons 20 are cooled to a temperature that allows their subsequent immediate further processing, e.g. winding onto reels.

[0039] The annealing module 1 is controlled by an electronic control module 16, which directly or indirectly regulates the temperature in the interior 3, the heating temperature of the heating means, in particular the temperature of the hot gas stream 15, and the speeds of the rollers 6-13.

[0040] Fig. 3 shows the annealing module 1 in the closed state with the housing door 17 folded down, which seals the interior 3. The housing door 17 has viewing windows 18 through which the operating personnel can monitor the correct running of the plastic ribbons 20. Furthermore, the housing door has a transparent cover 19 made of glass or plastic, which allows a view of the cooling rollers 12, 13 but prevents access to the cooling rollers for safety reasons.

[0041] Figures 1 and 2 show the annealing module in its open state. For clarity, the housing door 17 has been omitted in these illustrations.

[0042] List of reference symbols:

[0043] 1 Annealing Module

[0044] 2 housings

[0045] 3 Interior

[0046] 4 Entrance

[0047] 4a Inlet sealing lip

[0048] 5 Outlet

[0049] 5a Outlet sealing lip

[0050] 6, 7, 8, 9, 10, 11 rotating driven rollers

[0051] 12, 13 Cooling rollers

[0052] 14 hot gas blowers

[0053] 15 Hot gas stream

[0054] 15a reverse current

[0055] 16 Control module

[0056] 17 Housing door

[0057] 18 viewing windows

[0058] 19 transparent cover

[0059] 20 plastic wristbands

[0060] T Transport direction of the plastic ribbons VI Circumferential speed of the first roller group

[0061] V2 peripheral speed of the second roller group

[0062] V3 Circumferential speed of the second roller group

Claims

Claims:

1. Annealing module (1) of a device for producing stretched thermoplastic ribbons, comprising a housing (2) defining an interior space (3), wherein the housing (2) has an inlet (4) and an outlet (5) for the passage of the plastic ribbons (20) to be treated through the interior space (3), wherein in the interior space (3) a plurality of rotating driven rollers (6-11) are arranged axially parallel to one another and are designed to be at least partially wrapped around by the plastic ribbons (20), characterized in that the annealing module (1) is equipped with heating means for uniformly heating the interior space (3) to a temperature which is at least 70%, preferably at least 75%, of the melting temperature of the plastic ribbons (20) to be treated, and in that the rollers (6-11) are driven at such a rotational speed,that the ribbons, depending on their path through the annealing module (1), have a residence time in the annealing module of a maximum of 10 seconds, preferably a maximum of 5 seconds, even more preferably a maximum of 3 seconds., 2. Annealing module according to claim 1, characterized in that the heating means are designed for uniform heating of the interior (3) to a temperature of at most 5% above the melting temperature, preferably of at most 3% above the melting temperature, most preferably of at most the melting temperature, of the plastic ribbons (20) to be treated.

3. Annealing module according to claim 1 or 2, characterized in that the housing (2) is thermally insulated.

4. Annealing module according to one of the preceding claims, characterized in that the heating means comprise a hot gas stream (15) guided into the interior, wherein the hot gas stream (15) is preferably formed by at least one hot gas blower (14) arranged outside the housing (2), the outlet of which communicates with the interior (3).

5. Annealing module according to claim 4, characterized in that the hot gas flow (15) is designed as a circulating air flow in that it is fed to the interior space 3 and sucked off at another point in the interior space as a return flow (15a) and returned to the inlet of the hot gas blower (14).

6. Annealing module according to one of the preceding claims, characterized in that the heating means comprise heating elements arranged in the interior (3) of the housing (2), preferably electrical or inductive or heating fluid-flowing heating elements.

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

8. Annealing module according to one of the preceding claims, characterized in that the rotating driven rollers (6-11) are arranged so that their The plastic strips (20) wrap around the jacket surfaces at an angle of less than 360°, but preferably at least 150°.

9. Annealing module according to one of the preceding claims, characterized in that at least some of the rotatingly driven rollers (6-11) are combined to form at least two roller groups (6-7; 8-9; 10-11), the rollers (6-7; 8-9; 10-11) of a roller group each having the same circumferential speeds of their jacket surfaces, wherein - viewed in the transport direction (T) of the plastic strips (20) - each roller group (10-11; 8-9; 6-7) has a lower circumferential speed (V3; V2; V1) of the jacket surfaces of the rollers than the roller group (6-7; 8-9; 10-11) adjacent to it opposite the transport direction (T).

10. Annealing module according to one of the preceding claims, characterized by at least one rotatingly driven cooling roller (12, 13) which - seen in the transport direction (T) of the plastic ribbons (20) - is arranged downwards from the outlet (5) of the housing (2).

11. Annealing module according to one of the preceding claims, characterized in that a control module (16) is provided for setting and regulating the rotational speeds of the rollers and at least one further parameter selected from the interior temperature and / or the heating temperature of the heating means.

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

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

14. Annealing module according to one of the preceding claims, characterized in that it is adapted for the treatment of plastic ribbons (20) made of a polyester material, in particular PET, or a polyolefin, in particular PP, HOPE, LLDPE.

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