Title of Invention	PROCESS AND APPARATUS FOR CONTINUOUS POLYMERIZATION OF POLYMER IN SOLID PHASE
Abstract	The invention relates to a process and to an apparatus for continuous solid-state polymerization of particles, especially of a granule of polyesters and polyamides, characterized in that the particles (20) are polymerized and/or treated in at least one reactor (12), the at least one reactor (12) having a pressure below atmospheric pressure or being present in a chamber (12A) under a protective gas atmosphere.

Title of Invention

PROCESS AND APPARATUS FOR CONTINUOUS POLYMERIZATION OF POLYMER IN SOLID PHASE

Abstract

The invention relates to a process and to an apparatus for continuous solid-state polymerization of particles, especially of a granule of polyesters and polyamides, characterized in that the particles (20) are polymerized and/or treated in at least one reactor (12), the at least one reactor (12) having a pressure below atmospheric pressure or being present in a chamber (12A) under a protective gas atmosphere.

Full Text	Process and apparatus for continuous polymerization of polymer in solid phase The invention relates to a process for continuous polymerization as claimed in claim 1 and an apparatus for carrying out the process as claimed in claim 11. Polyester and polyamide polymers are prepared in batch- wise or continuous polymerizations in the liquid phase (melt phase, MP), e.g. DE 103 22 106.9A1. To increase their viscosity and/or to achieve particular properties, the polymer produced in this way, which is present in particle form, in particular pellet form or powder form, is subjected to a solid- state polymerization (SSP). This occurs, in particular, in the preparation of poly- ester polymers for the production of bottles and high- strength threads. Here, a base polymer having an intrinsic viscosity (I.V.) of, for example, from 0.30 dl/g to 0.65 dl/g is prepared in the melt: phase. One possible way of determining the intrinsic viscosity is a measurement in phenol/dichlorobenzene (60:40) at 25 +/- 0.01°C. The pellets produced in this way are subsequently subjected to a solid-state polymerization in which the viscosity is increased to, for example, from 0.80 to > 1.0 I.V. and the acetaldehyde (AA) content is reduced to less than 1 ppm. A similar procedure is employed in the solid-state polymerization of Nylon 6, where, for example, pellets having a relative viscosity (e.g. measured in 96% H2S04, 1% by weight, at 25 +/- °C) of 2.4 or 2,7 is polymerized to a higher viscosity, e.g. 3.2 or 4.0 or above. In the processes known hitherto, the pellets from the melt phase are cooled a liter pelletization and stored. The pelletized material is subsequently reheated, partially crystallized (:.n the case of polyester) and dried, subsequently made uniform in further crystallizations and reaction stages and subsequently polymerized in a fixed-bed reactor. In the method of preparing polyesters which is described in DE 10 2004 015 515 Al, the polymer prepared in the melt phase is not cooled after pelletization and crystallized without further introduction of heat, purely by the latent heat of the polymer. The solid-state polymerization which follows these processes is carried out under an inert gas atmosphere, e.g. nitrogen or CO2, to avoid damage to the product by atmospheric oxygen and to remove the process vapors formed from the system. The fixed-bed reactors are usually upright vessels in which the product to be treated, viz. the pelletized material, flows under its own weight from the top downward and the gas flows in countercurrent from the bottom upward. The gas is preheated to the necessary working temperature. In another apparatus (WO 2004/018541 Al), the polymerization is carried out in the solid state in a horizontal, rotating reactor. The process vapors to be removed are likewise carried away by means of nitrogen. Since nitrogen is expensive, the reactor is operated in the recycle mode. The materials given off from the product in the solid-state polymerization (SSP) , e.g. ethylene glycol, acetaldehydes, water and other undesirable vapors and gases, are taken up by the inert gas and have to be removed from the gas circuit by means of complicated purification apparatuses. The apparatuses for this purpose are very complicated and the energy consumption is high. The purification of the circulated gas is effected either by catalytic combustion at temperatures of about 400°C or by means of a wet scrub using ethylene glycol (polyester) or water (Nylon 6). These processes have the further disadvantage that relatively large amounts of gas have to be circulated in order to achieve good uniform flow through the SSP reactor since only in this way can uniform treatment of the polymer be achieved and only in this way is there a sufficient driving difference between pellets and gas to achieve an acceptable residence time. A further disadvantage of the upright reactors is the large construction height which requires building heights of up to 50 m. A process in the rotating horizontal reactor (WO 2004/018541 Al) has the further disadvantage that the mechanical design of the reactors is complicated and expensive since the product and gas have to be introduced and removed from the reactor using gastight rotating glands. It is also known that the solid-state polymerization can be carried out in batch processes using tumble dryers or cone dryers or similar apparatuses. However, the throughput here is small because of the size and residence time required. In addition, heat transfer to achieve the necessary reaction temperature is low, which increases the residence time. A further disadvantage of the batch processes is the relative nonuniformity of the product obtained. However, an advantage of the batch process, which is usually carried out under reduced pressure, is the relatively low discoloration and the relatively high brilliance of the product obtained. In the present process and reactor, the disadvantages of the previously described processes are avoided. According to the invention, the continuous solid-state polymerization is carried out by at least partly polymerizing and/or treating the particles in at least one reactor at a pressure below atmospheric pressure. In this way, relatively low discoloration and relatively high brilliance of the product are achieved. Carrying out the process step in a chamber under reduced pressure or a chamber containing a protective gas atmosphere allows a construction without a rotating gland. For the present purposes, particles are, for example, pellets, powder, coarse powder or fine pellets. The pressure is advantageously below 0.8 bar abs, preferably below 0.6 bar abs, particularly preferably below 0.3 bar abs. In a further advantageous embodiment, the polymerization is carried out in an essentially horizontal reactor. Essentially horizontal reactors can be made very long, so that very large plants can also be realized. It is advantageous for the; polymerization to be in the form of an after-polymerization following a melt polymerization. It is particularly advantageous for the particles (e.g. the pelletized material) being heated immediately to a higher temperature after a melt polymerization without further cooling and/or storage and subsequently being passed to an after- polymerization in at least one reactor. The heating of the particles (e.g. the granules) after the melt polymerization and pelletization is advantageously effected by conveying by means of a hot gas or in a fluidized bed. As an alternative or in addition, it is advantageous for the heating of the pellets after the melt polymerization and pelletization to be carried out in an agitated or unagitated fixed- bed reactor or in a vibrating conveyor. The object is achieved by an apparatus having the features of claim 11. Here, the apparatus of the invention comprises at least one reactor which serves for the at least partial polymerization and/or treatment of the particles (e.g. the pellets), with the pressure in the reactor being kept below atmospheric pressure or the reactor being kept under a protective gas atmosphere in a chamber. The reactor is advantageously configured as an essentially horizontal reactor. For operation below atmospheric pressure, it is advantageous for the at least one reactor to have a vacuum chamber (12A) or protective gas chamber (12A) and the at least one reactor (12) to be located in a vacuum chamber (12A) or protective gas chamber (12A) and/or the at least one reactor (12) itself to form the vacuum chamber (12A) or the protective gas chamber (12A). The use of vacuum or the use of a protective gas chamber allows a design without a rotating gland. In a further embodiment, the at least one reactor has a rotatable tube reactor. In such reactors, good heat transport can be brought about. It is also advantageous for the at least one reactor to have a cradle or be formed by a cradle, with the particles (e.g. the pellets) being able to be moved back and forth in the cradle. Efficient heat transport can also be brought about in this way. To convey the pellets in the at least one reactor, the latter has means for producing vibration, with the means for producing vibration ensuring that the particles (e.g. the pellets) can be conveyed from the inlet to the outlet. In a particularly advantageous embodiment, the at least one reactor is preceded by a prereactor, in particular a smaller, rotating tube reactor. In this way, the particles (e.g. the pellets) can efficiently be brought to a higher temperature. The at least one reactor is advantageously inclined in the direction of the outlet so that a natural transport direction results from gravity. To improve heat transfer, the at least one reactor has internals for mixing the particles (e.g. the pellets) and for reducing backmixing. It is also advantageous for internals to be configured as static mixers and/or movable mixers. It is advantageous for the at least one reactor to be able to be heated by means of a gaseous or liquid heating medium. As an alternative or in addition, it is advantageous for the at least one reactor and/or the product in the at least one reactor to be heated by means of an infrared radiator and/or ultrasound radiator and/or microwave radiator. In an embodiment which is simple to operate and easy to maintain, the at least one reactor which is located in the vacuum chamber does not have any rotating glands for the product, vacuum or heating media. The at least one reactor advantageously has at least one heating zone with internal and/or external heating facilities. In the case of more than two heating zones, these are advantageously operated at different or identical temperatures. The invention is illustrated below with the aid of illustrative embodiments; in the figures of the description: fig. 1 shows an illustrative first embodiment of the process and the apparatus; fig. 2 shows an illustrative second embodiment with mechanical transport of the pellets; fig. 3 shows an illustrative third embodiment having a preheater; fig. 4 shows an illustrative fourth embodiment having a preheater which is located upstream of the pellet transport; fig. 5, 5A, 5B show an illustrative first embodiment of a reactor for an after- polymerization and two sectional views of variants; fig. 6, 6A show an illustrative second embodiment of a reactor for an after- polymerization and a sectional view; fig. 7, 7A-C show an illustrative third embodiment of a reactor for an after- polymerization, with three positions of a cradle for the pellets (fig. 7A-C) being shown in section; fig. 8, 8A, 8B show an illustrative fourth embodiment of a reactor having a cradle with internals and a heating jacket; fig. 9, 9A show an illustrative fifth embodiment of a reactor having a preceding rotary tube reactor; fig. 10, 10A show an illustrative sixth embodiment of a reactor having a cradle and a preceding rotary tube reactor. In the embodiments of the process of the invention and the embodiments of the apparatus of the invention, the polymer is, after the melt-phase polymerization, cooled during pelletization as an extruded strand (extrudates) or underwater (spherical pellets) only to such an extent that it can be cut, i.e. pellets can be produced. The pellets are subsequently separated from the water in a centrifuge or a similar apparatus and immediately reheated and passed to the solid-state polymerization (SSP) . Even if pellets are used in the description of the embodiments, it is in principle also possible to use particles such as coarse powder or powder. The heating of the pellets can be carried out in a conventional crystallizer (fixed bed or fluidized bed) or by means of transport in a stream of hot gas. Here, the temperature and residence time of the apparatus for heating the pellets or the hot gas transport are set so that the pelletized material crystallizes and is dried. In the case of the preparation of polyester, crystallization is carried out to such an extent that the pellets no longer stick and enter the SSP at a temperature very close to the solid-state polymerization temperature. In the case of Nylon 6, the residence time and temperature are set so that the pellets enter the SSP at a temperature very close to the solid-state polymerization temperature. Before going into detail regarding the individual illustrative embodiments of the process and the apparatus, a few general remarks which essentially apply to all figures will be made beforehand. The polyester polymer prepared in a continuous polycondensation plant has an intrinsic viscosity which is sufficiently high, e.g. from 0.3 to 0.6 I.V., to be able to produce a uniform pelletized material in an extrusion pelletizatior. plant or underwater pelletization. In the pelletization plant, a pelletized material 20 having a pellet weight of from 4 to 30 mg per pellet, advantageously from 4 to 15 mg, is produced. In a centrifuge 1 (or in a screen which is not shown in figures 1 to 4), the pelletized material 20 is freed of the cutting water and coarse material is removed in a downstream screen 2. The pelletized material 20 then falls into a hot gas transport apparatus 4 and is heated and transportec oy the hot gases. Crystallization and drying occur here. The pelletized material 20 after transport and before entry into the solid-state polymerization has a degree of crystallization of at least 25% and a temperature of at least 180°C, advantageously more than 200°C. As an alternative, immediate heating and partial crystallization are carried out in a conventional crystallizer (e.g. agitated fixed bed, vibrational conveyor or fluidized bed) . From there, it is conveyed by means of hot gas transport to the SSP reactor 12. The reactor 12 for the solid-state polymerization (after-polymerization) comprises a horizontal, slightly inclined if necessary, tube reactor (also referred to as rotary tube oven; see figures 5 and 9) or a cradle (also referred to as rocking oven; see figures 7, 8, 10) . The tube reactor 12 (or the cradle configured as reactor 12) is located in a vacuum chamber (12A) and can thus be operated under reduced pressure (i.e. below atmospheric pressure) without complicated vacuum-tight rotating glands being required for the introduction and discharge of pelletized material 20 and heating medium. The size of the reactors is therefore not subject to any limits. In the illustrative embodiments, the reactor is shown in conjunction with a vacuum chamber 12A. However, each illustrative embodiment can also be modified by the reactor 12 being present under protective gas (e.g. nitrogen) in a chamber 12A. The examples are to be interpreted as a chamber 12A having a pressure below atmospheric pressure (vacuum chamber) or being filled with protective gas. The tube reactor 12 is a rotating tube and can have internals in its interior so as to set the pelletized material 20 in continual motion and prevent backmixing of feed granules and output granules. The tube reactor 12 (or the cradle configured as reactor 12) can be heated by means of heating media such as heat transfer oil or steam or similar heating media. To increase the working temperature, the tube reactor 12 (or the cradle configured as reactor 12) can be preceded by a more quickly rotating heated smaller tube reactor 17 (see figures 9 and 10) ; in this case, no heating is required for the tube reactor 12 ;or the cradle configured as reactor 12). The reduced pressure and any further heating brings about the after-polymerization. The vapors and gases given off are extracted by suction by the vacuum facility, the condensable vapors are condensed and passed to wastewater treatment or recirculated to the melt-phase polymerization. The incondensable offgases are given off to the atmosphere or passed to a conventional offgas purification or incineration. These are amounts of offgas which are caused by leakages. They are therefore significantly smaller than the amount of offgas from the catalytic offgas combustion of conventional solid-state polymerizations. Operation under reduced pressure avoids damage to the pelletized material 20 by residual oxygen which is normally present in a conventional solid-state polymerization. Furthermore, as a result of the reduced pressure, the driving differential pressure/partial pressure is significantly greater than in conventional SSP, so that a more uniform product (from pellet to pellet and within the pellet itself) is achieved. In conventional plants, the substances emitted from the pelletized material 20 can ceposit on the pelletized material 20 before they are removed from the system by means of the nitrogen. In the process of the invention, immediate vaporization under reduced pressure occurs. In this way, deposits cannot form on the pelletized material, as a result o:: which the product attains higher brilliance. Description of the process and the apparatus as shown in fig. 1 Pelletized material 20 and water come from the pelletization apparatus. In the centrifuge 1, the pelletized material 20 is separated from the water. The water goes back to the pelletization plant and the pelletized material 20 falls onto a screen 2 on which it is separated from small and large particles. The pelletized material 20 has a temperature of from 70 to 150°C (polyester!. From the screen, the pelletized material 20 goes via a transport device 3, e.g. a star feeder, to a transport apparatus 4. The transport: apparatus 4 is in this case operated by means of hot gas, e.g. nitrogen. In the transport apparatus 4, the pelletized material 20 is heated to the reaction temperature necessary for the solid-state polymerization, e.g. 200-210°C (polyester). The transport gas is circulated. The pelletized material 20 is separated from the transport gas in a cyclone 5 and falls into a collection vessel 6. The transport gas goes to a blower 7 and is recirculated by this through a filter 8 and a heating body 10 to the transport device 3. If required, a deoxo facility 9 can be used to remove undesirable oxygen from the transport gas. From the collection vessel 6, the pelletized material 20 goes via a metering device 11 into the SSP reactor 12 for the after-polymerization. The reactor 12 operates at below atmospheric pressure (reduced pressure) which is generated by a vacuum facility 13. Various embodiments of the reactor 12 are described with the aid of figures 5 tc 10. Condensable substances which are extracted from the reactor 12 with the incondensable gases are condensed in a condensation system 14. In the SSP reactor 12, the pelletized material 20 is after-polymerized to a higher viscosity. During this after-polymerization, the pelletized material 20 is continually kept in motion by rotation of the reactor 12. Backmixing of the pelletized material 20 is avoided by means of suitable internals in the reactor 12 (e.g. static mixers) . At the outlet of the reactor 12, the pelletized material 20 falls into a funnel and into a suitable discharge device 15. From the discharge device, the pelletized material 20 goes into a pellet cooler 16 and from there to packaging or storage hoppers. Cooling of the pelletized material 20 is preferably carried out under an inert gas atmosphere. Description of the process and the apparatus as shown in fig. 2 The basic structure of the second embodiment as shown in fig. 2 corresponds to that of the first embodiment, so that reference is made to the above description. As in the first embodiment shown in fig. 1, pelletized material 20 and water come from the pelletization apparatus. Unlike the first embodiment, the transport apparatus 4 transports the material mechanically under hot gas, e.g. nitrogen. During transport, the peiietized material 20 is heated to the reaction temperature necessary for the solid-state polymerization, e.g. 200-210°C (polyester). The recirculation of the transport gas corresponds to that of the first embodiment. From the collection vessel 6, the peiietized material 20 goes via a metering device 11 into the SSP reactor 12 for the after-polymerization, with the work-up of the after-polymer corresponding to the first embodiment. Description of the process and the apparatus shown in fig. 3 As in the first embodiment, transport of the peiietized material in the third embodiment of the process of the invention is effected by means of hot gas, e.g. nitrogen. The transport gas is circulated. The peiietized material 20 is separated from the gas in the cyclone 5 and falls into a pellet preheater 4A. In the preheater 4A, the peiietized material 20 is brought to the reaction temperature necessary for the solid-state polymerization, e.g. 200-210˚C (polyester). From there, the material goes into the collection vessel 6. The work-up of the circulating gas and the configuration of the reactor 12 are as in the first two embodiments. Description of the process and the apparatus shown in fig. 4 Pelletized material 20 and water come from the pelletization apparatus. In the centrifuge 1, the pelletized material 20 is separated from the water. The water goes back to the pelletization plant and the granulated material 20 falls onto a screen 2 in which it is separated from small and large particles. The pelletized material has a temperature of from 70 to 150°C (polyester). From the screen 2, the pelletized material 20 goes via a transport device 3, e.g. a star feeder, into the pellet preheater 4A which in the fourth embodiment is located upstream of the transport apparatus 4 . In the preheater 4A, the pelletized material is heated to the reaction temperature necessary for the solid-state polymerization, e.g. 200-210°C (polyester). From the preheater 4A, the pelletized material 20 goes via a transport metering device 3A into a granule transport apparatus 4. The material is conveyed, for example, by means of nitrogen. The transport gas is circulated, with the work-up of the circulating gas and the configuration of the after- polymerization corresponding to the first embodiment. Figures 5 to 10 describe various embodiments of the SSP reactor 12. These embodiments can be integrated into one of the above-described process variants. Description of the SSP reactor 12 as shown in fig. 5, 5A, 5B In the first embodiment of the SSP reactor 12 for the after-polymerization, the reactor is configured as an essentially horizontal tube reactor 12. The essentially horizontal tube reactor 12 is located in a vacuum chamber 12A. As an alternative, the vacuum chamber 12A can also be configured as protective gas chamber 12A. The reactor 12 rests on rollers 12C (see sectional view in fig. 5B) which can be driven by a drive 12B and can thus set the reactor 12 into rotary motion. The drive 12B can also be effected by means of a crown gear or similar devices. The pelletized material is conveyed from the collection vessel 6 by means of a metering device 11 into the rotating reactor 12. The pelletized material 20 moves as a result of the inclination of the reactor 12 and/or internal chicanes from the inlet to the outlet of the reactor 12. The speed of rotation of the reactor 12 can be adjusted, by means of which the residence time of the pelletized material 20 can be influenced. The output from the reactor falls as pelletized material 20 into a funnel and is discharged by means of the discharge means 15. Inlet and outlet for pelletized material and also the gas extraction 12G (vacuum port) and any inlets and outlets for heating media are connected rigidly to the upright vacuum chamber 12A. The reactor can be equipped with a means of heating, e.g. a heating jacket or a radiant heater (e.g. microwave). In the sectional view of fig. 5A, a heating jacket 12H is shown. Description of the SSP reactor as shown in fig. 6, 6A The second embodiment as shown in fig. 6 basically corresponds to the embodiment depicted in fig. 5, with the tube reactor 12 here being provided with movable internals 12E with a drive 12D. As an alternative, the internals can also be configured without a drive, e.g. as static mixers. Description of the SSP reactor as shown in fig. 7, 7A, 7B, 7C The reactor 12 has a cradle or is formed by the cradle which is located in a vacuum chamber 12A. The cradle is configured as a long half tube which has a cross section similar to a baby's cradle. This is moved back and forth by means of a drive, in a manner similar to a baby's cradle. The pelletized material 20 is continually kept in motion by the appropriate internals and the movement of the cradle, and back- mixing of pelletized material introduced and material to be discharged is also prevented. The reactor 12 rests on rollers 12C which can be ariven by the drive 12B and set the reactor 12 into rotating motion from left to right. Sectional views of the reactor 12 are shown in fig. 7A-C. Fig. 7A shows the cradle 12 rotated to the left, while fig. 7C shows the cradle rotated to the right. Fig. 7B shows the middle position of the reactor 12. The pelletized material 20 (shown as the dark area in fig. 7A to 7C) is moved relatively slowly. The drive can also be effected by means of a crown gear or similar devices. The pelletized material is conveyed from the collection vessel 6 by means of a metering device 11 into the rotating reactor. The pelletized material 20 moves as a result of the inclination of the reactor 12 and/or internal chicanes 12E from the inlet to the outlet. The number of movements of the reactor 12 can be adjusted, by means of which the residence time can be influenced. The output from the reactor falls as pellet ized material 20 into a funnel and is discharged by means of the discharge means 15. Inlet and outlet for pelletized material and also the gas extraction 12G (vacuum port) and any inlets and outlets for heating media are connected rigidly to the upright vacuum chamber 12A, The reactor 12 is, in this embodiment, equipped with radiant heating 12F which heats the pelletized material 20 from above. The motion of the reactor 12 ensures uniform heating of the pelletized material. Description of the SSP reactor shown in fig. 8, 8A, 8B The design corresponds to fig. 7 but the reactor 12 has a heating jacket 12H and/or fixed or moving chicanes 12E. Description of the SSP reactor shown in fig. 9 The design corresponds to :he preceding figures 7 and 8 (tube reactor 12) but the actual reactor 12 is preceded by a small rotary tube reactor 17 in which the pelletized material 20 can quickly and effectively be brought to a higher operating temperature. The sectional view of fig. 9A shows the pelletized material 20 in the interior of the tube reactor 12. As an alternative to the rotary tube reactor 17, it is also possible to use a cradle. Description of the SSP reactor shown in fig. 10: The design corresponds to the embodiments depicted in the preceding fig. 8 or 9 (cradle) , but the reactor 12 is preceded by a small rotary tube reactor 12 in which the pelletized material 20 can quickly and effectively be brought to a higher operating temperature. Claims: 1. A process for the continuous solid-state polymerization of particles, in particular pellets of polyesters and polyamides, characterized in that the particles (20) are polymerized and/or treated in at least one reactor (12) which has a pressure below atmospheric pressure or is located under a protective gas atmosphere in a chamber (12A). 2. The process as claimed in claim 1, characterized in that the pressure in the at least one reactor (12) is below 0.8 bar abs. 3. The process as claimed in claim 1 or 2, characterized in that the pressure in the at least one reactor (12) is below 0.6 bar abs. 4. The process as claimed in at least one of the preceding claims, characterized in that the pressure in the at least one reactor (12) is below 0.3 bar abs. 5. The process as claimed in at least one of the preceding claims, characterized in that the polymerization is carried out in an essentially horizontal reactor (12). 6. The process as claimed in at least one of the preceding claims, characterized in that the polymerization is configured as an after- polymerization following a preceding melt polymerization. 7. The process as claimed in at least one of the preceding claims, characterized in that the particles (20) after a melt polymerization are immediately heated tc a higher temperature without further cooling and/or storage and subsequently fed to an after-polymerization in the reactor (12). 8. The process as claimed in claim 7, characterized in that the heating of the particles (20) after the melt polymerization and pelletization is effected by hot gas transport (4) or in a fluidized bed. 9. The process as claimed in at least one of claims 6 to 8, characterized in that the heating of the particles (20) after the melt polymerization and pelletization is effected in an agitated or unagitated fixed-bed reactor. 10. The process as claimed in at least one of claims 6 to 9, characterized in that the heating of the particles (20) after the melt polymerization and pelletization is effected in a vibrating conveyor. 11. An apparatus for carrying out the process as claimed in claim 1, characterized by at least one reactor (12) for the at least partial polymerization and/or treatment of particles (20), with the pressure in the reactor (12) being kept below atmospheric pressure or the reactor being kept under a protective gas atmosphere in a chamber. 12. The apparatus as claimed in claim 11, characterized in that the at least one reactor (12) is configured as an essentially horizontal reactor. 13. The apparatus as claimed in claim 11 or 12, characterized in that the at least one reactor (12) has a vacuum chamber (12A) or protective gas chamber (12A), the at. least one reactor 12) is located in a vacuum chamber (12A) or protective gas chamber (12A) and/or the at least one reactor (12) itself forms the vacuum chamber (12A) or the protective gas chamber (12A). The apparatus as claimed in at least one of claims 11 to 13, characterized in that the at least one reactor (12) has a rctatable tube reactor. 15. The apparatus as claimed in at least one of claims 11 to 14, characterized in that the at least one reactor (12) has a cradle or is formed by a cradle, with the particles (20) being able to be moved back and forth in the cradle. 16. The apparatus as claimed in at least one of claims 11 to 15, characterized in that the at least one reactor (12) has means of inducing vibration to ensure that the particles can be conveyed from the inlet to the outlet. 17. The apparatus as claimed in at least one of claims 11 to 16, characterized in that the at least one reactor (12) is preceded by a prereactor ill) in particular a smaller rotating tube reactor. 18. The apparatus as claimed in at least one of claims 11 to 17, characterized in that the at least one reactor (12) is inclined toward the outlet. 19. The apparatus as claimed in at least one of claims 11 to 18, characterized in that the at least one reactor (12) has internals (12E) for mixing the particles (20) and for reducing backmixing. 20. The apparatus as claimed in claim 19, characterized in that the internals (12E) are configured as static mixers and/or movable mixers. 21. The apparatus as claimed in at least one of claims 11 to 20, characterized in that the at least one reactor (12) can be heated by means of a gaseous or liquid heating medium (12F, 12H). 22. The apparatus as claimed in at least one of claims 11 to 21, characterized in that the at least one reactor (12) and/or the product in the at least one reactor (12) is heated by means of an infrared radiator and/or ultrasound radiator and/or microwave radiator. 23. The apparatus as claimed in at least one of claims 11 to 22, characterized in that the at least one reactor (12) which is located in the vacuum chamber does not require any rotating glands for the product, vacuum or heating media. 24. The apparatus as claimed in at least one of claims 11 to 23, characterized in that the at least one reactor (12) has at least one heating zone with internal and/or external heating facilities which in the case of more than two heating zones can be operated at different or identical temperatures. The invention relates to a process and to an apparatus for continuous solid-state polymerization of particles, especially of a granule of polyesters and polyamides, characterized in that the particles (20) are polymerized and/or treated in at least one reactor (12), the at least one reactor (12) having a pressure below atmospheric pressure or being present in a chamber (12A) under a protective gas atmosphere.

Full Text

Process and apparatus for continuous polymerization of
polymer in solid phase
The invention relates to a process for continuous
polymerization as claimed in claim 1 and an apparatus
for carrying out the process as claimed in claim 11.
Polyester and polyamide polymers are prepared in batch-
wise or continuous polymerizations in the liquid phase
(melt phase, MP), e.g. DE 103 22 106.9A1.
To increase their viscosity and/or to achieve
particular properties, the polymer produced in this
way, which is present in particle form, in particular
pellet form or powder form, is subjected to a solid-
state polymerization (SSP).
This occurs, in particular, in the preparation of poly-
ester polymers for the production of bottles and high-
strength threads. Here, a base polymer having an
intrinsic viscosity (I.V.) of, for example, from
0.30 dl/g to 0.65 dl/g is prepared in the melt: phase.
One possible way of determining the intrinsic viscosity
is a measurement in phenol/dichlorobenzene (60:40) at
25 +/- 0.01°C.
The pellets produced in this way are subsequently
subjected to a solid-state polymerization in which the
viscosity is increased to, for example, from 0.80 to
> 1.0 I.V. and the acetaldehyde (AA) content is reduced
to less than 1 ppm.
A similar procedure is employed in the solid-state
polymerization of Nylon 6, where, for example, pellets
having a relative viscosity (e.g. measured in 96% H2S04,
1% by weight, at 25 +/- °C) of 2.4 or 2,7 is
polymerized to a higher viscosity, e.g. 3.2 or 4.0 or
above.

In the processes known hitherto, the pellets from the
melt phase are cooled a liter pelletization and stored.
The pelletized material is subsequently reheated,
partially crystallized (:.n the case of polyester) and
dried, subsequently made uniform in further
crystallizations

and reaction stages and subsequently polymerized in a
fixed-bed reactor.
In the method of preparing polyesters which is
described in DE 10 2004 015 515 Al, the polymer
prepared in the melt phase is not cooled after
pelletization and crystallized without further
introduction of heat, purely by the latent heat of the
polymer.
The solid-state polymerization which follows these
processes is carried out under an inert gas atmosphere,
e.g. nitrogen or CO2, to avoid damage to the product by
atmospheric oxygen and to remove the process vapors
formed from the system.
The fixed-bed reactors are usually upright vessels in
which the product to be treated, viz. the pelletized
material, flows under its own weight from the top
downward and the gas flows in countercurrent from the
bottom upward. The gas is preheated to the necessary
working temperature.
In another apparatus (WO 2004/018541 Al), the
polymerization is carried out in the solid state in a
horizontal, rotating reactor. The process vapors to be
removed are likewise carried away by means of nitrogen.
Since nitrogen is expensive, the reactor is operated in
the recycle mode. The materials given off from the
product in the solid-state polymerization (SSP) , e.g.
ethylene glycol, acetaldehydes, water and other
undesirable vapors and gases, are taken up by the inert
gas and have to be removed from the gas circuit by
means of complicated purification apparatuses.
The apparatuses for this purpose are very complicated
and the energy consumption is high. The purification of

the circulated gas is effected either by catalytic
combustion at temperatures of about 400°C or by means
of a wet scrub using ethylene glycol (polyester) or
water (Nylon 6).

These processes have the further disadvantage that
relatively large amounts of gas have to be circulated
in order to achieve good uniform flow through the SSP
reactor since only in this way can uniform treatment of
the polymer be achieved and only in this way is there a
sufficient driving difference between pellets and gas
to achieve an acceptable residence time.
A further disadvantage of the upright reactors is the
large construction height which requires building
heights of up to 50 m.
A process in the rotating horizontal reactor (WO
2004/018541 Al) has the further disadvantage that the
mechanical design of the reactors is complicated and
expensive since the product and gas have to be
introduced and removed from the reactor using gastight
rotating glands.
It is also known that the solid-state polymerization
can be carried out in batch processes using tumble
dryers or cone dryers or similar apparatuses. However,
the throughput here is small because of the size and
residence time required. In addition, heat transfer to
achieve the necessary reaction temperature is low,
which increases the residence time.
A further disadvantage of the batch processes is the
relative nonuniformity of the product obtained.
However, an advantage of the batch process, which is
usually carried out under reduced pressure, is the
relatively low discoloration and the relatively high
brilliance of the product obtained.
In the present process and reactor, the disadvantages
of the previously described processes are avoided.
According to the invention, the continuous solid-state

polymerization is carried out by at least partly
polymerizing and/or treating the particles in at least
one reactor at a pressure below atmospheric pressure.
In this way, relatively low discoloration and
relatively high brilliance of the product are achieved.
Carrying out the process step in a chamber under
reduced pressure or a chamber containing a protective
gas atmosphere allows a construction without a rotating
gland.

For the present purposes, particles are, for example,
pellets, powder, coarse powder or fine pellets.
The pressure is advantageously below 0.8 bar abs,
preferably below 0.6 bar abs, particularly preferably
below 0.3 bar abs.
In a further advantageous embodiment, the
polymerization is carried out in an essentially
horizontal reactor. Essentially horizontal reactors can
be made very long, so that very large plants can also
be realized.
It is advantageous for the; polymerization to be in the
form of an after-polymerization following a melt
polymerization. It is particularly advantageous for the
particles (e.g. the pelletized material) being heated
immediately to a higher temperature after a melt
polymerization without further cooling and/or storage
and subsequently being passed to an after-
polymerization in at least one reactor.
The heating of the particles (e.g. the granules) after
the melt polymerization and pelletization is
advantageously effected by conveying by means of a hot
gas or in a fluidized bed. As an alternative or in
addition, it is advantageous for the heating of the
pellets after the melt polymerization and pelletization
to be carried out in an agitated or unagitated fixed-
bed reactor or in a vibrating conveyor.
The object is achieved by an apparatus having the
features of claim 11. Here, the apparatus of the
invention comprises at least one reactor which serves
for the at least partial polymerization and/or
treatment of the particles (e.g. the pellets), with the
pressure in the reactor being kept below atmospheric
pressure or the reactor being kept under a protective

gas atmosphere in a chamber.
The reactor is advantageously configured as an
essentially horizontal reactor.
For operation below atmospheric pressure, it is
advantageous for the at least one reactor to have a
vacuum chamber (12A) or protective gas chamber (12A)
and the at least one reactor (12) to be located in a
vacuum chamber (12A) or protective gas chamber (12A)
and/or the at least one reactor (12) itself to form the
vacuum chamber (12A) or the protective gas chamber
(12A).

The use of vacuum or the use of a protective gas
chamber allows a design without a rotating gland.
In a further embodiment, the at least one reactor has a
rotatable tube reactor. In such reactors, good heat
transport can be brought about.
It is also advantageous for the at least one reactor to
have a cradle or be formed by a cradle, with the
particles (e.g. the pellets) being able to be moved
back and forth in the cradle. Efficient heat transport
can also be brought about in this way.
To convey the pellets in the at least one reactor, the
latter has means for producing vibration, with the
means for producing vibration ensuring that the
particles (e.g. the pellets) can be conveyed from the
inlet to the outlet.
In a particularly advantageous embodiment, the at least
one reactor is preceded by a prereactor, in particular
a smaller, rotating tube reactor. In this way, the
particles (e.g. the pellets) can efficiently be brought
to a higher temperature.
The at least one reactor is advantageously inclined in
the direction of the outlet so that a natural transport
direction results from gravity.
To improve heat transfer, the at least one reactor has
internals for mixing the particles (e.g. the pellets)
and for reducing backmixing. It is also advantageous
for internals to be configured as static mixers and/or
movable mixers.
It is advantageous for the at least one reactor to be
able to be heated by means of a gaseous or liquid

heating medium. As an alternative or in addition, it is
advantageous for the at least one reactor and/or the
product in the at least one reactor to be heated by
means of an infrared radiator and/or ultrasound
radiator and/or microwave radiator.

In an embodiment which is simple to operate and easy to
maintain, the at least one reactor which is located in
the vacuum chamber does not have any rotating glands
for the product, vacuum or heating media.
The at least one reactor advantageously has at least
one heating zone with internal and/or external heating
facilities. In the case of more than two heating zones,
these are advantageously operated at different or
identical temperatures.
The invention is illustrated below with the aid of
illustrative embodiments; in the figures of the
description:
fig. 1 shows an illustrative first embodiment
of the process and the apparatus;
fig. 2 shows an illustrative second embodiment
with mechanical transport of the
pellets;
fig. 3 shows an illustrative third embodiment
having a preheater;
fig. 4 shows an illustrative fourth embodiment
having a preheater which is located
upstream of the pellet transport;
fig. 5, 5A, 5B show an illustrative first embodiment
of a reactor for an after-
polymerization and two sectional views
of variants;
fig. 6, 6A show an illustrative second embodiment
of a reactor for an after-
polymerization and a sectional view;

fig. 7, 7A-C show an illustrative third embodiment
of a reactor for an after-
polymerization, with three positions of
a cradle for the pellets (fig. 7A-C)
being shown in section;
fig. 8, 8A, 8B show an illustrative fourth embodiment
of a reactor having a cradle with
internals and a heating jacket;

fig. 9, 9A show an illustrative fifth embodiment
of a reactor having a preceding rotary
tube reactor;
fig. 10, 10A show an illustrative sixth embodiment
of a reactor having a cradle and a
preceding rotary tube reactor.
In the embodiments of the process of the invention and
the embodiments of the apparatus of the invention, the
polymer is, after the melt-phase polymerization, cooled
during pelletization as an extruded strand (extrudates)
or underwater (spherical pellets) only to such an
extent that it can be cut, i.e. pellets can be
produced. The pellets are subsequently separated from
the water in a centrifuge or a similar apparatus and
immediately reheated and passed to the solid-state
polymerization (SSP) . Even if pellets are used in the
description of the embodiments, it is in principle also
possible to use particles such as coarse powder or
powder.
The heating of the pellets can be carried out in a
conventional crystallizer (fixed bed or fluidized bed)
or by means of transport in a stream of hot gas. Here,
the temperature and residence time of the apparatus for
heating the pellets or the hot gas transport are set so
that the pelletized material crystallizes and is dried.
In the case of the preparation of polyester,
crystallization is carried out to such an extent that
the pellets no longer stick and enter the SSP at a
temperature very close to the solid-state
polymerization temperature.
In the case of Nylon 6, the residence time and
temperature are set so that the pellets enter the SSP

at a temperature very close to the solid-state
polymerization temperature.
Before going into detail regarding the individual
illustrative embodiments of the process and the
apparatus, a few general remarks which essentially
apply to all figures will be made beforehand.

The polyester polymer prepared in a continuous
polycondensation plant has an intrinsic viscosity which
is sufficiently high, e.g. from 0.3 to 0.6 I.V., to be
able to produce a uniform pelletized material in an
extrusion pelletizatior. plant or underwater
pelletization.
In the pelletization plant, a pelletized material 20
having a pellet weight of from 4 to 30 mg per pellet,
advantageously from 4 to 15 mg, is produced.
In a centrifuge 1 (or in a screen which is not shown in
figures 1 to 4), the pelletized material 20 is freed of
the cutting water and coarse material is removed in a
downstream screen 2. The pelletized material 20 then
falls into a hot gas transport apparatus 4 and is
heated and transportec oy the hot gases.
Crystallization and drying occur here. The pelletized
material 20 after transport and before entry into the
solid-state polymerization has a degree of
crystallization of at least 25% and a temperature of at
least 180°C, advantageously more than 200°C.
As an alternative, immediate heating and partial
crystallization are carried out in a conventional
crystallizer (e.g. agitated fixed bed, vibrational
conveyor or fluidized bed) . From there, it is conveyed
by means of hot gas transport to the SSP reactor 12.
The reactor 12 for the solid-state polymerization
(after-polymerization) comprises a horizontal, slightly
inclined if necessary, tube reactor (also referred to
as rotary tube oven; see figures 5 and 9) or a cradle
(also referred to as rocking oven; see figures 7, 8,
10) .
The tube reactor 12 (or the cradle configured as
reactor 12) is located in a vacuum chamber (12A) and

can thus be operated under reduced pressure (i.e. below
atmospheric pressure) without complicated vacuum-tight
rotating glands being required for the introduction and
discharge of pelletized material 20 and heating medium.
The size of the reactors is therefore not subject to
any limits.
In the illustrative embodiments, the reactor is shown
in conjunction with a vacuum chamber 12A. However, each
illustrative embodiment can also be modified by the
reactor 12 being present under protective gas (e.g.
nitrogen) in a chamber 12A. The examples are to be
interpreted as a chamber 12A having a pressure below
atmospheric pressure (vacuum chamber) or being filled
with protective gas.

The tube reactor 12 is a rotating tube and can have
internals in its interior so as to set the pelletized
material 20 in continual motion and prevent backmixing
of feed granules and output granules.
The tube reactor 12 (or the cradle configured as
reactor 12) can be heated by means of heating media
such as heat transfer oil or steam or similar heating
media.
To increase the working temperature, the tube reactor
12 (or the cradle configured as reactor 12) can be
preceded by a more quickly rotating heated smaller tube
reactor 17 (see figures 9 and 10) ; in this case, no
heating is required for the tube reactor 12 ;or the
cradle configured as reactor 12).
The reduced pressure and any further heating brings
about the after-polymerization. The vapors and gases
given off are extracted by suction by the vacuum
facility, the condensable vapors are condensed and
passed to wastewater treatment or recirculated to the
melt-phase polymerization. The incondensable offgases
are given off to the atmosphere or passed to a
conventional offgas purification or incineration. These
are amounts of offgas which are caused by leakages.
They are therefore significantly smaller than the
amount of offgas from the catalytic offgas combustion
of conventional solid-state polymerizations.
Operation under reduced pressure avoids damage to the
pelletized material 20 by residual oxygen which is
normally present in a conventional solid-state
polymerization. Furthermore, as a result of the reduced
pressure, the driving differential pressure/partial
pressure is significantly greater than in conventional
SSP, so that a more uniform product (from pellet to
pellet and within the pellet itself) is achieved.

In conventional plants, the substances emitted from the
pelletized material 20 can ceposit on the pelletized
material 20 before they are removed from the system by
means of the nitrogen. In the process of the invention,
immediate vaporization under reduced pressure occurs.
In this way, deposits cannot form on the pelletized
material, as a result o:: which the product attains
higher brilliance.
Description of the process and the apparatus as shown
in fig. 1
Pelletized material 20 and water come from the
pelletization apparatus. In the centrifuge 1, the
pelletized material 20 is separated from the water. The
water goes back to the

pelletization plant and the pelletized material 20
falls onto a screen 2 on which it is separated from
small and large particles. The pelletized material 20
has a temperature of from 70 to 150°C (polyester!.
From the screen, the pelletized material 20 goes via a
transport device 3, e.g. a star feeder, to a transport
apparatus 4. The transport: apparatus 4 is in this case
operated by means of hot gas, e.g. nitrogen. In the
transport apparatus 4, the pelletized material 20 is
heated to the reaction temperature necessary for the
solid-state polymerization, e.g. 200-210°C (polyester).
The transport gas is circulated. The pelletized
material 20 is separated from the transport gas in a
cyclone 5 and falls into a collection vessel 6. The
transport gas goes to a blower 7 and is recirculated by
this through a filter 8 and a heating body 10 to the
transport device 3. If required, a deoxo facility 9 can
be used to remove undesirable oxygen from the transport
gas.
From the collection vessel 6, the pelletized material
20 goes via a metering device 11 into the SSP reactor
12 for the after-polymerization. The reactor 12
operates at below atmospheric pressure (reduced
pressure) which is generated by a vacuum facility 13.
Various embodiments of the reactor 12 are described
with the aid of figures 5 tc 10.
Condensable substances which are extracted from the
reactor 12 with the incondensable gases are condensed
in a condensation system 14.
In the SSP reactor 12, the pelletized material 20 is
after-polymerized to a higher viscosity. During this
after-polymerization, the pelletized material 20 is
continually kept in motion by rotation of the reactor

12. Backmixing of the pelletized material 20 is avoided
by means of suitable internals in the reactor 12 (e.g.
static mixers) . At the outlet of the reactor 12, the
pelletized material 20 falls into a funnel and into a
suitable discharge device 15.
From the discharge device, the pelletized material 20
goes into a pellet cooler 16 and from there to
packaging or storage hoppers. Cooling of the pelletized
material 20 is preferably carried out under an inert
gas atmosphere.

Description of the process and the apparatus as shown
in fig. 2
The basic structure of the second embodiment as shown
in fig. 2 corresponds to that of the first embodiment,
so that reference is made to the above description.
As in the first embodiment shown in fig. 1, pelletized
material 20 and water come from the pelletization
apparatus. Unlike the first embodiment, the transport
apparatus 4 transports the material mechanically under
hot gas, e.g. nitrogen. During transport, the
peiietized material 20 is heated to the reaction
temperature necessary for the solid-state
polymerization, e.g. 200-210°C (polyester).
The recirculation of the transport gas corresponds to
that of the first embodiment.
From the collection vessel 6, the peiietized material
20 goes via a metering device 11 into the SSP reactor
12 for the after-polymerization, with the work-up of
the after-polymer corresponding to the first
embodiment.
Description of the process and the apparatus shown in
fig. 3
As in the first embodiment, transport of the peiietized
material in the third embodiment of the process of the
invention is effected by means of hot gas, e.g.
nitrogen.
The transport gas is circulated. The peiietized
material 20 is separated from the gas in the cyclone 5
and falls into a pellet preheater 4A. In the preheater
4A, the peiietized material 20 is brought to the
reaction temperature necessary for the solid-state

polymerization, e.g. 200-210˚C (polyester). From there,
the material goes into the collection vessel 6.
The work-up of the circulating gas and the
configuration of the reactor 12 are as in the first two
embodiments.
Description of the process and the apparatus shown in
fig. 4
Pelletized material 20 and water come from the
pelletization apparatus. In the centrifuge 1, the
pelletized material 20 is separated from the water. The
water goes back to the pelletization plant and the
granulated material 20 falls onto a screen 2 in which
it is separated from small and large particles. The
pelletized material has a temperature of from 70 to
150°C (polyester).

From the screen 2, the pelletized material 20 goes via
a transport device 3, e.g. a star feeder, into the
pellet preheater 4A which in the fourth embodiment is
located upstream of the transport apparatus 4 . In the
preheater 4A, the pelletized material is heated to the
reaction temperature necessary for the solid-state
polymerization, e.g. 200-210°C (polyester).
From the preheater 4A, the pelletized material 20 goes
via a transport metering device 3A into a granule
transport apparatus 4. The material is conveyed, for
example, by means of nitrogen.
The transport gas is circulated, with the work-up of
the circulating gas and the configuration of the after-
polymerization corresponding to the first embodiment.
Figures 5 to 10 describe various embodiments of the SSP
reactor 12. These embodiments can be integrated into
one of the above-described process variants.
Description of the SSP reactor 12 as shown in fig. 5,
5A, 5B
In the first embodiment of the SSP reactor 12 for the
after-polymerization, the reactor is configured as an
essentially horizontal tube reactor 12.
The essentially horizontal tube reactor 12 is located
in a vacuum chamber 12A. As an alternative, the vacuum
chamber 12A can also be configured as protective gas
chamber 12A.
The reactor 12 rests on rollers 12C (see sectional view
in fig. 5B) which can be driven by a drive 12B and can
thus set the reactor 12 into rotary motion. The drive
12B can also be effected by means of a crown gear or
similar devices.

The pelletized material is conveyed from the collection
vessel 6 by means of a metering device 11 into the
rotating reactor 12. The pelletized material 20 moves
as a result of the inclination of the reactor 12 and/or
internal chicanes from the inlet to the outlet of the
reactor 12. The speed of rotation of the reactor 12 can
be adjusted, by means of which the residence time of
the pelletized material 20 can be influenced.
The output from the reactor falls as pelletized
material 20 into a funnel and is discharged by means of
the discharge means 15.

Inlet and outlet for pelletized material and also the
gas extraction 12G (vacuum port) and any inlets and
outlets for heating media are connected rigidly to the
upright vacuum chamber 12A.
The reactor can be equipped with a means of heating,
e.g. a heating jacket or a radiant heater (e.g.
microwave). In the sectional view of fig. 5A, a heating
jacket 12H is shown.
Description of the SSP reactor as shown in fig. 6, 6A
The second embodiment as shown in fig. 6 basically
corresponds to the embodiment depicted in fig. 5, with
the tube reactor 12 here being provided with movable
internals 12E with a drive 12D.
As an alternative, the internals can also be configured
without a drive, e.g. as static mixers.
Description of the SSP reactor as shown in fig. 7, 7A,
7B, 7C
The reactor 12 has a cradle or is formed by the cradle
which is located in a vacuum chamber 12A.
The cradle is configured as a long half tube which has
a cross section similar to a baby's cradle. This is
moved back and forth by means of a drive, in a manner
similar to a baby's cradle. The pelletized material 20
is continually kept in motion by the appropriate
internals and the movement of the cradle, and back-
mixing of pelletized material introduced and material
to be discharged is also prevented.
The reactor 12 rests on rollers 12C which can be ariven
by the drive 12B and set the reactor 12 into rotating
motion from left to right. Sectional views of the

reactor 12 are shown in fig. 7A-C. Fig. 7A shows the
cradle 12 rotated to the left, while fig. 7C shows the
cradle rotated to the right. Fig. 7B shows the middle
position of the reactor 12. The pelletized material 20
(shown as the dark area in fig. 7A to 7C) is moved
relatively slowly.
The drive can also be effected by means of a crown gear
or similar devices.

The pelletized material is conveyed from the collection
vessel 6 by means of a metering device 11 into the
rotating reactor. The pelletized material 20 moves as a
result of the inclination of the reactor 12 and/or
internal chicanes 12E from the inlet to the outlet. The
number of movements of the reactor 12 can be adjusted,
by means of which the residence time can be influenced.
The output from the reactor falls as pellet ized
material 20 into a funnel and is discharged by means of
the discharge means 15.
Inlet and outlet for pelletized material and also the
gas extraction 12G (vacuum port) and any inlets and
outlets for heating media are connected rigidly to the
upright vacuum chamber 12A,
The reactor 12 is, in this embodiment, equipped with
radiant heating 12F which heats the pelletized material
20 from above. The motion of the reactor 12 ensures
uniform heating of the pelletized material.
Description of the SSP reactor shown in fig. 8, 8A, 8B
The design corresponds to fig. 7 but the reactor 12 has
a heating jacket 12H and/or fixed or moving chicanes
12E.
Description of the SSP reactor shown in fig. 9
The design corresponds to :he preceding figures 7 and 8
(tube reactor 12) but the actual reactor 12 is preceded
by a small rotary tube reactor 17 in which the
pelletized material 20 can quickly and effectively be
brought to a higher operating temperature. The
sectional view of fig. 9A shows the pelletized material
20 in the interior of the tube reactor 12. As an
alternative to the rotary tube reactor 17, it is also

possible to use a cradle.
Description of the SSP reactor shown in fig. 10:
The design corresponds to the embodiments depicted in
the preceding fig. 8 or 9 (cradle) , but the reactor 12
is preceded by a small rotary tube reactor 12 in which
the pelletized material 20 can quickly and effectively
be brought to a higher operating temperature.

Claims:
1. A process for the continuous solid-state
polymerization of particles, in particular pellets
of polyesters and polyamides, characterized in
that the particles (20) are polymerized and/or
treated in at least one reactor (12) which has a
pressure below atmospheric pressure or is located
under a protective gas atmosphere in a chamber
(12A).
2. The process as claimed in claim 1, characterized
in that the pressure in the at least one reactor
(12) is below 0.8 bar abs.
3. The process as claimed in claim 1 or 2,
characterized in that the pressure in the at least
one reactor (12) is below 0.6 bar abs.
4. The process as claimed in at least one of the
preceding claims, characterized in that the
pressure in the at least one reactor (12) is below
0.3 bar abs.
5. The process as claimed in at least one of the
preceding claims, characterized in that the
polymerization is carried out in an essentially
horizontal reactor (12).
6. The process as claimed in at least one of the
preceding claims, characterized in that the
polymerization is configured as an after-
polymerization following a preceding melt
polymerization.
7. The process as claimed in at least one of the
preceding claims, characterized in that the
particles (20) after a melt polymerization are

immediately heated tc a higher temperature without
further cooling and/or storage and subsequently
fed to an after-polymerization in the reactor
(12).

8. The process as claimed in claim 7, characterized
in that the heating of the particles (20) after
the melt polymerization and pelletization is
effected by hot gas transport (4) or in a
fluidized bed.
9. The process as claimed in at least one of claims 6
to 8, characterized in that the heating of the
particles (20) after the melt polymerization and
pelletization is effected in an agitated or
unagitated fixed-bed reactor.
10. The process as claimed in at least one of claims 6
to 9, characterized in that the heating of the
particles (20) after the melt polymerization and
pelletization is effected in a vibrating conveyor.
11. An apparatus for carrying out the process as
claimed in claim 1, characterized by at least one
reactor (12) for the at least partial
polymerization and/or treatment of particles (20),
with the pressure in the reactor (12) being kept
below atmospheric pressure or the reactor being
kept under a protective gas atmosphere in a
chamber.
12. The apparatus as claimed in claim 11,
characterized in that the at least one reactor
(12) is configured as an essentially horizontal
reactor.
13. The apparatus as claimed in claim 11 or 12,
characterized in that the at least one reactor
(12) has a vacuum chamber (12A) or protective gas
chamber (12A), the at. least one reactor 12) is
located in a vacuum chamber (12A) or protective
gas chamber (12A) and/or the at least one reactor
(12) itself forms the vacuum chamber (12A) or the

protective gas chamber (12A).
The apparatus as claimed in at least one of claims
11 to 13, characterized in that the at least one
reactor (12) has a rctatable tube reactor.

15. The apparatus as claimed in at least one of claims
11 to 14, characterized in that the at least one
reactor (12) has a cradle or is formed by a
cradle, with the particles (20) being able to be
moved back and forth in the cradle.
16. The apparatus as claimed in at least one of claims
11 to 15, characterized in that the at least one
reactor (12) has means of inducing vibration to
ensure that the particles can be conveyed from the
inlet to the outlet.
17. The apparatus as claimed in at least one of claims
11 to 16, characterized in that the at least one
reactor (12) is preceded by a prereactor ill) in
particular a smaller rotating tube reactor.
18. The apparatus as claimed in at least one of claims
11 to 17, characterized in that the at least one
reactor (12) is inclined toward the outlet.
19. The apparatus as claimed in at least one of claims
11 to 18, characterized in that the at least one
reactor (12) has internals (12E) for mixing the
particles (20) and for reducing backmixing.
20. The apparatus as claimed in claim 19,
characterized in that the internals (12E) are
configured as static mixers and/or movable mixers.
21. The apparatus as claimed in at least one of claims
11 to 20, characterized in that the at least one
reactor (12) can be heated by means of a gaseous
or liquid heating medium (12F, 12H).
22. The apparatus as claimed in at least one of claims
11 to 21, characterized in that the at least one
reactor (12) and/or the product in the at least

one reactor (12) is heated by means of an infrared
radiator and/or ultrasound radiator and/or
microwave radiator.

23. The apparatus as claimed in at least one of claims
11 to 22, characterized in that the at least one
reactor (12) which is located in the vacuum
chamber does not require any rotating glands for
the product, vacuum or heating media.
24. The apparatus as claimed in at least one of claims
11 to 23, characterized in that the at least one
reactor (12) has at least one heating zone with
internal and/or external heating facilities which
in the case of more than two heating zones can be
operated at different or identical temperatures.

The invention relates to a process and to an apparatus
for continuous solid-state polymerization of particles,
especially of a granule of polyesters and polyamides,
characterized in that the particles (20) are
polymerized and/or treated in at least one reactor
(12), the at least one reactor (12) having a pressure
below atmospheric pressure or being present in a
chamber (12A) under a protective gas atmosphere.

Documents:

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Patent Number

268442

Indian Patent Application Number

4528/KOLNP/2008

PG Journal Number

36/2015

Publication Date

04-Sep-2015

Grant Date

31-Aug-2015

Date of Filing

07-Nov-2008

Name of Patentee

AQUAFIL ENGINEERING GMBH

Applicant Address

DUSTERHAUPTSTRASSE 13 13469 BERLIN

Inventors:

#	Inventor's Name	Inventor's Address
1	KARASIAK, DIRK	NIEDERBARNIMSTRASSE 52A 16548 GLIENICKE
2	KARASIAK WOLF	ELSENBRUCHSTRASSE 18 13467 BERLIN

PCT International Classification Number

B01J 3/00

PCT International Application Number

PCT/EP2007/004211

PCT International Filing date

2007-05-11

PCT Conventions:

#	PCT Application Number	Date of Convention	Priority Country
1	10 2006 022 299.7	2006-05-11	Germany