Title of Invention	METHOD AND REACTOR FOR THE CONTINUOUS PRODUCTION OF POLYMERS
Abstract	The invention relates to a method and a device for the continuous production of polymers. According to said method, monomers are initially obtained in a vertical reactor having a plurality of reaction zones (A, B,C), subsequently, prepolymers and then the desired polymer are obtained. At least one reaction zone of the reactor (1) is embodied as a disk cage reactor or a ring disk reactor.

Full Text

Description The invention relates to a process for the continuous production of polymers, in particular of condensates and preferably polyester polymers, from the starting materials for the monomer or monomers and their conversion into the polymers in a single reactor having a plurality of reaction zones and a reactor in cascade form whose last chamber is configured as an annular disk reactor or disk-cage reactor. The use of a plurality of horizontal and vertical reactors with or without built-in stirrers or mixing devices for carrying out continuously operated poly- merizations is known. In all these processes, the reactors are operated under different operating conditions which differ in terms of pressure and temperature. The reactors are connected by double- walled pipes which are heated. The transport of the product between the various reactors is generally effected by means of pumps or by means of the different operating pressure. US Patent No. 6,096,838 discloses an apparatus for polycondensation that can produce polyester of the desired quality efficiently, with a minimum of energy and minimizing the necessary reactor structure and arrangement. The large number of reactors and connecting elements make the plants very large, require multistory buildings having a large area, elaborate construction measures and therefore make the plants very expensive. An annular disk reactor in which the conversion of prepolymers into polymers by condensation is carried out is likewise known from US patent 3,761,059. This annular disk reactor is used as a horizontal reactor. This reactor has the advantage that it is only partly filled with product. The product to be reacted is lifted from, the bottom by means of the annular disks and is conveyed in thin layers into the vapor space and flows downward with continual renewal of the product surface. As a result of the formation of the thin layers, the volatile components in the polymer can easily escape and the ;reaction process can be influenced in an advantageous manner. Although the stirring device is not continually located below the level of the product, it is continually wetted and is repeatedly rinsed and washed by the product. However, a disadvantage of these annular disk reactors or disk-cage reactors is that they operate effectively only above a particular product viscosity. If the viscosity is too low, the product does not remain on the annular disks, so that it is not transported into the gas space and sufficient films cannot be formed. Instead the annular disks only cut like knives through water. It is an object of the invention to device a process and a reactor for the continuous product of polymers which can be realized in a simple manner without high plant costs and an apparatus for carrying out the process. According to the invention, the polymer is produced by conversion of the starting materials into monomer or monomers, further conversion into prepolymers and on into the polymers in a single vertical reactor which is divided into at least two, superposed reaction zones of which at least one zone comprises an annular disk reactor and/or a disk-cage reactor. In a particular embodiment of the process, an end reactor for the further polymerization is installed downstream. This downstream end reactor is advanta- geously an annular disk reactor or a disk-cage reactor. In place of an end reactor, it is also possible for an SSP (solid state polycondensation) to be provided downstream. In the process of the invention, the starting materials for the production of the monomers are mixed with one another in appropriate ratios outside the vertical reactor and are then introduced at the top into the uppermost reaction stage. It is also possible to introduce the starting materials separately into the first reaction zone. Here, the conversion into the desired monomers occurs. The monomers are taken off continuously and conveyed via lines, which may be located within or outside the reactor, to the reaction zone located underneath. The vapors and gases formed in the production of monomers or prepolymer can be conveyed from one reaction stage to another reaction stage via connecting lines between the reaction stages and can subsequently be discharged. Of course, the vapors formed in the respective reaction can also be discharged individually from each reaction zone. To achieve better mixing and acceleration of the reaction, a stirrer can be provided in the first reaction zone of the vertical reactor. Here, the stirrer can be located centrally or eccentrically. The stirrer itself can be mounted at one or both ends. The reaction can be carried out under superatmospheric, subatmospheric or atmospheric pressure and the reaction mixture can be cooled and heated in the desired way. Cooling or heating is achieved by means of a jacket installed on the outer surface of the reactor and/or installed heat exchanger elements through which cooling or heating media (gaseous or liquid) can flow. As indicated above, the reaction product from the first reaction zone is transferred via lines which can be located within or outside the reactor into the second reaction zone and is there converted into prepolymers having the desired degree of polymerization or desired viscosity. The low-boiling condensation products given off as gases or vapors result in sufficient circulation of the product, so that a product which is sufficiently uniform in terms of its viscosity is obtained and is taken off at the lower end of the second reaction zone. In this reaction zone, too, the course of the reaction can be influenced in a desired manner by means of superatmospheric or subatmospheric pressure. Likewise, a jacket on the exterior circumference of the reactor or built-in heat exchanger elements through which cooling or heating media can be passed is/are also provided here. In a particular embodiment, the second reaction zone is divided by dividing walls so that the medium is forced to follow a predetermined route. For example, the medium is conveyed in a spiral from the outside inward or in the reverse direction and then downward to flow out into the third reaction zone. The reaction product is introduced into the third reaction zone via lines at one or more points on the outer edge of the reactor. In a particular embodiment, the product from the second reaction zone is heated to a higher temperature outside the reactor before it enters the third reaction zone. In addition, the reactor is surrounded by a jacket or provided with internal heat exchangers which can serve for the introduction of heating media or cooling media in the third reaction zone, too. In the third reaction zone, the conversion of the prepolymer into the desired polymer occurs. The products having relatively low boiling points formed in the reaction are discharged at the top of the third reaction zone and are processed further outside the reactor. Devices which reduce the carry-over of product particles into the downstream condensers are provided in the upper part of each reaction stage. According to the invention, the third reaction zone is configured as an annular disk reactor or disk-cage reactor. To fit the annular disk reactor or disk-cage reactor known per se to the hemispherical shape of the reactor of the invention, the stirring elements installed on the stirring or transport device have differing diameters. They increase from the wall of the reactor to the middle. To achieve even better and more uniform condensation, dividing walls and/or overflows are provided in the third reaction zone in the hemisphere. Thus, the entire third reaction zone is divided into a plurality of small reaction stages, with material flow occurring from the outside inward. The material flow is determined by the throughput and the rotational speed of the stirring and transport device. As the stirring elements move, the material taken up by them flows back into the same chamber. The product flows from chamber to chamber over the weirs. To achieve complete emptying of the chambers formed by the dividing walls and/or overflows, drain holes or other drainage facilities are provided at the lowest point in the walls. Should the viscosity of the melt in the outer small reaction stages still be so low that the melt does not adhere sufficiently to the stirring elements, the transport of the material to the surface occurs by means of scooping elements installed on the shaft or the support frame or on the disks or stirring elements. The diameter of the individual stirring elements, for example annular disks, is so large that only a small gap remains between the wall of the reactor and the outer edge of the stirring elements. The level of the reaction medium in the individual small reaction stages is determined by the height of the overflows. The stirring elements of the stirring devices are installed on the latter so that the center point of the stirring elements lies on the axis of rotation of the stirring devices. This ensures that each stirring element performs a symmetrical motion when it rotates about the axis of the stirring devices. An advantage is that material which adheres to and is therefore lifted by the stirring elements is renewed on each rotation without the stirring and transport device being adversely affected. All parts dipping into the fluid material are wetted during one full rotation when the level is appropriate. Parts of the stirring element surfaces which are not wetted by dipping into the fluid are gradually covered by a film of the material adhering to the wetted areas during the rotational motion. These films then travel, like the adhering material in the case of complete wetting of the stirring element surfaces, to the inner edge of the surface and fall as a film into the fluid material. When annular disks are used, the stirring elements can advantageously be constructed so that the annular areas of the annular disks are perforated or slotted. Embodiments in which the perforated or slotted annular disks are provided with openings which are larger the higher the viscosity are particularly advantageous. In this way, a viscosity which changes during the process can be taken into account in a simple way for an optimal process. An arrangement of the stirring elements with different distances between them, namely becoming smaller or larger from the outside to the inside, is likewise advantageous for the same purpose. The distances between the individual separation or overflow elements can also be chosen freely depending on the desired course of the reaction. The arrangement of a differing number of stirring elements in the individual smaller reaction stages of the third reaction zone can likewise be chosen freely. It merely has to be ensured that a product which is substantially uniform in terms of its properties is obtained in each case. For this purpose, it has to be ensured that the stirring elements move the product, result in film formation and/or transport from the product liquid into the vapor space. It is advantageous for at least one end disk of the support frame to be elastic. In this way, it is ensured that thermal expansions between the reactor wall and stirring device are taken up by the stirring device and not by the actual shaft bearings. After passing the last dividing wall or the last overflow weir, the finished product is taken off in the middle at the lowest point of the vertical reactor. Should the desired degree of polymerization not yet have been achieved, the product obtained in the vertical reactor can be transferred to a downstream horizontal annular disk reactor or disk-cage reactor. It is likewise possible to pelletize the product obtained and process it further in a further separate process, e.g. SSP. The downstream annular disk reactor is a simple vessel with an installed stirring device. It is advantageous for the geometric components used as stirring elements to have little play where they move past the bottom part of the reactor. The material is continuously introduced at one end of the downstream annular disk reactor and conveyed to the other end, during which process it is continually lifted from the melt as a thin film on the stirring elements and flows back into the melt while undergoing the reaction. The desired polymer is discharged at the other end. The low-boiling products formed are removed from the reactor above the melt. Both in the case of the stirring devices provided in the third reaction zone in the vertical reactor and in the case of the stirring devices provided in the downstream horizontal reactor, the geometric elements provided as stirring elements can be arranged on the shaft or the support frame with differing angles of inclination. The invention is illustrated below with the aid of the drawings. In the accompanying drawings : Fig. 1 shows a variant of the reactor of the invention, in section; Fig. 2 shows a further variant of the reactor of the invention with downstream end reactor, in section; Fig. 3a-k show different embodiments of an annular disk or a stirring element; Fig. 4a-g show different embodiments of the stirring elements in plan view; Fig. 5a and b show forced routes for the material in the second reaction zone B of the reactor 1 in plan view; Fig. 6a-c show details of the bottommost reaction zone . Figure 1 shows the vertical reactor 1 for the production of polyesters. However, other polymers can in principle be produced using the reactor of the invention. The reactor 1 has three reaction zones A, B, C which are superposed in the vertical reactor. The starting materials 31, 32 for producing the monomers as starting material for the desired polymer are mixed in a mixer 33 outside the reactor 1 and conveyed from a stock vessel 34 via line 30 into the reactor 1 at the top. The introduction of the mixture of the raw materials can also be effected at the bottom of the reaction zone A. In the first reaction zone A of the reactor 1, the starting materials are converted into the monomer. The monomers are taken off via the first line 35 and intro- duced into the second reaction zone B below the liquid level of the reaction mixture. In the second reaction zone, the further reaction to form the monomer or par- tial polymerization of the monomers occurs. The partial polymerization is controlled in a desired manner by means of the reaction temperature and/or the pressure. To influence the reaction temperature, the reactor 1 is enclosed by a heating jacket and/or provided with heat exchangers 47. Each of the reaction zones A, B, C can be provided with separate jacket segments 2, 3, 4 or the heating jacket and/or the heat exchangers 47 are all supplied with cooling or heating media. To reduce the carry-over of product particles into the condensers (not shown) and recirculate them to the reaction zone, precipitators 46 can be provided in the individual reaction zones. After the desired viscosity of the prepolymer has been reached in the second reaction zone B, this is taken off at the lowermost end of the second reaction zone B by means of a line 9. The prepolymers are, after they have been heated in heating devices 37 additionally provided outside the plant, introduced into the third reaction zone C at one or more points at the outer edge. An annular disk reactor or disk-cage reactor is located in the third reaction zone C, with the wall of the reactor 1 being configured as a hemisphere or part of a hemisphere 7 at the bottom end. To circulate and move the material, a stirring device 5 is provided. The stirring device 5 comprises a hollow shaft 12 on which mixing means 15a to k, e.g. annular disks, segments of annular disks, scoop-shaped profiles and the like, are arranged. To achieve better control of the polymerization, dividing walls and/or overflow weirs 8 are provided in the hemisphere 7. One or more of the mixing means 15 are provided between the individual dividing walls and/or overflow weirs 8. Material flow is achieved by means of the mixing means 15, e.g. annular disks, which may be vertical or inclined. The course of the reaction is controlled so that the polymers have reached the desired degree of polymerization after reaching the middle zone formed by the dividing walls or overflow weirs 8. The polymers are then discharged from the reactor 1 through the line 38. Figure 2 shows the vertical reactor 1 which corresponds essentially to the reactor 1 described in Figure 1 with a downstream horizontal end reactor 39. As a modification to the course of the reaction described for Figure 1, the starting materials 31, 32 are introduced directly without prior mixing into the first reaction zone A of the vertical reactor 1. In this variant, the conversion into the monomer is aided by a stirrer 6. The reaction product is transferred from the first reaction zone A into the second reaction zone B, as in the description for Figure 1. As a modification, the reaction product from the second reaction zone B is introduced directly via line 9 into the third reaction zone C at one or more points at the outer edge of the reactor 1. Heating elements (not shown) can be provided at the inlet. An annular disk reactor or disk-cage reactor is located in the third reaction zone C, as described in the case of Figure 1. Here, the stirring elements consist of annular disks provided with holes 16. The reaction of the prepolymers to form the polymers is, in this variant, carried out only to a particular viscosity or to a particular molecular weight and the material taken off at the outlet 38 is then transferred to a downstream end reactor 39. The end reactor 39 consists of an annular disk reactor or disk-cage reactor known per se. In the end reactor 39, the polymerization is completed. The annular disk reactor is a jacket-heated double- walled vessel having a heating space 40. The material introduced at the inlet 41 is conveyed by the stirring device 5 from the inlet 41 to the outlet 42 and in the process is mixed, stirred through and subjected to a high surface action for the further polymerization. An outlet 43 is provided for discharge of vapors or gases. The stirring device 5 is in principle constructed as has been described for the third reaction zone C of Figure 1. As a modification, no shaft 11 but instead a rotatable support frame comprising the end disks 44 and the longitudinal spars 14 is provided. The mixing means 15, e.g. annular disks, are fastened to the longitudinal spars 14. The individual annular disks 15 are fastened so that they are inclined to the longitudinal spars 14. Likewise, scooping elements can be provided in place of the annular disks 15 or the scooping elements are additionally arranged on the annular disks 15. The longitudinal spars 14 can be round or profiled. Likewise, perforations can be provided in the longitudinal spars 14, particularly when profiles are employed. The perforations help the viscous reaction mixture to run down during the reaction occurring during passage through the end reactor 39. Illustrative embodiments of the stirring devices 15 are shown in Figures 3a to 3k and Figures 4a to 4g, without these constituting a restriction. Figure 3a shows a stirring device having a shaft 11 with annular disk segments provided with scooping elements 48. Figure 3b shows a stirring device having a hollow cylinder 12 with annular disks provided with scooping elements 48. Figure 3c shows an annular disk which has equally spaced holes 16 over its entire area. The annular disk is located on the hollow cylinder in whose interior a perforated annular disk is likewise located. Figure 3d depicts an annular disk. Figure 3e shows a perforated annulus which is held on the shaft 11 by means of a number of struts. Figure 3f shows segments of an annulus which are each attached to the shaft by means of two struts acting as stirring devices. Figure 3g shows a modification of the variant shown in Figure 3e. Figure 3h shows a plurality of perforated ring segments arranged on the shaft 11. Figure 3i shows perforated segments of an annulus which are each attached to the shaft 11 by means of two struts. Figure 3k shows a full disk as stirring element. Figure 4a shows a variant of the stirring device in which the scooping elements 48 are located on the annular disks 15. The annular disks are located on the hollow cylinder 12. Figures 4b and 4c show stirring elements as annular disks or segments of annular disks. Figure 4d shows the same arrangement as Fig. 4a, but the hollow cylinder is perforated. Figure 4e shows a modification of Figure 4d in which a plurality of neighboring scooping elements 48 are combined to form a larger scooping element. Figure 4f depicts a variant having obliquely mounted annular disks. Figure 4g shows various variants of the perforations 16 and scooping elements 4 8 which can be employed individually or in combination. The annular disks 15 or 15a to k depicted in Figures 1 and 2 can have the configurations shown in Figures 3a- k. They comprise, for example, a flat annular sheet provided with a multiplicity of holes 16. This annular disk is connected in the region of its circumference to the longitudinal spars 14, e.g. by the longitudinal spars 14 being passed through the annular disk and welded in place. Likewise, the annular disks 15 or other mixing means used as stirring devices can be connected at their outer areas or inner areas to the longitudinal spars 14. Figures 5a and b show possibilities for the forced routing of the product in the second reaction zone B of the reactor 1. These arrangements comprise dividing walls 45 which are wound concentrically within one another and direct the material from the outside inward or in the reverse direction and then downward into the third reaction stage. Improved homogeneity of the monomer or prepolymer is achieved in this way. Figures 6a to 6c show different variants of the bottommost reaction zone. Different support construc- tions for the disks 15 are shown here. Figure 6a shows a shaft 11, Figure 6b shows a hollow cylinder (cage) and Figure 6c shows a support frame construction. WE CLAIM: 1. A process for the continuous production of polymers, characterized in * that, the production of the monomers and the polymers is carried out in a vertical reactor having at least two, vertically superposed reaction zones of which at least one zone comprises an annular disk reactor or a disk-cage reactor. 2. The process as claimed in claim 1, wherein a downstream end reactor (39) is provided for further polymerization. 3. The process as claimed in claims 1 or 2, wherein said downstream reactor is a solid-state polycondensation stage (SSP) reactor. 4. The process as claimed in at least one of the preceding claims, wherein polycondensates or polyesters are produced. 5. The process as claimed in at least one of the preceding claims, wherein at least one raw material is fed directly into the reactor (1). 6. The process as claimed in at least one of the preceding claims, wherein at least one raw material is fed as a paste-like mixture directly into the reactor (1). 7. The process as claimed in at least one of the preceding claims, wherein the material flow in the interior of the vertical reactor (|) occurs in the direction of gravity between at least two reaction zones. 8. The process as claimed in at least one of the preceding claims, wherein the material flow in the interior of the reactor (1) occurs in the direction opposite to gravity between at least two reaction zones. 9. The process as claimed in at least one of the preceding claims, wherein the production of the monomer or monomers occurs in a reaction zone (A) above the middle of the reactor (1) and the production of the polymer occurs below the middle of the reactor (1) and the production of the polymer occurs below the middle of the reactor (1). lO.The process as claimed in at least one of the preceding claims, wherein the production of the monomer or monomers occurs in a reaction zone (A) below the middle of the reactor (1) and the production of the polymer occurs above the middle of the reactor (1). 11.The process as claimed in at least one of the preceding claims, wherein an end reaction occurs in the downstream end reactor (39). 12.The process as claimed in at least one of the preceding claims, wherein the individual reaction zones (A, B, C) are operated at different pressures or temperatures or at different pressures and temperatures. 13.The process as claimed in at least one of the preceding claims, wherein the monomers are heated to the required reaction temperature before entering the reaction zone(s) for conversion into the polymers, 14.The process as claimed in at least one of the preceding claims, wherein the monomers are heated to the required reaction temperature by means of internal heat exchangers after entering the reaction zone(s) for conversion into the polymer. 15.A vertical reactor for carrying out the process as claimed in any of ' claims 1 to 14, wherein the reactor (1) is divided into at least two superposed reaction zones of which at least one zone comprises an ' annular disk reactor or a disk-cage reactor. 16.The reactor as claimed in claim 15, wherein a plurality of heating zones are provided, said heating zones having internal or external heating or cooling devices. 17.The reactor as claimed in claim 15 or 16, wherein devices (46) which prevent carrying over of product particles into the downstream condensers are provided in one or more reaction stages. 18.The reactor as claimed in at least one of claims 15 to 17, wherein stirring devices (5,6) mounted at one or both ends are provided in one or more reaction zones of the reactor. 19.The reactor as claimed in at least one of claims 15 to 18, wherein one of the reaction zones, in particular, the bottommost reaction zone, is configured as an annular disk reactor or a disk-cage reactor (20). 20.The reactor as claimed in at least one of claims 15 to 19, wherein the reactor wall in the region of the annular disk reactor or disk-cage reactor (20) is configured as a hemisphere or part of a hemisphere (7). 21.The reactor as claimed in claim 20, wherein the hemisphere or part of a hemisphere (7) is provided with dividing walls or overflow weirs (8). 22.The reactor as claimed in claim 20, wherein the hemisphere or part of a hemisphere (7) is provided with dividing walls and overflow weirs (8). 23.The reactor as claimed in at least one of claims 15 to 22, wherein in the case of the annu71ar disk region or disk-cage region (20) being configured as a hemisphere (7),a product inlet (9) is arranged in the outer region and the outlet (10) for the finished product is arranged centrally. 24.The reactor as claimed in at least one of claims 15 to 23, wherein in the case of the annular disk region or disk-cage region (20) being configured as a hemisphere (7), a product inlet (9) is arranged at two or more points in the outer region. 25.The reactor as claimed in at least one of claims 15 to 24, wherein the dividing walls or overflow weirs (8) have drainage facilities to allow complete emptying. 26.The reactor as claimed in at least one of claims 15 to 24, wherein the dividing walls and overflow weirs (8) have drainage facilities to allow complete emptying. 27.The reactor as claimed in at least one of claims 15 to 25, wherein shafts (11) or hollow cylinders (cages) or longitudinal spars (14) fitted with stirring elements (15) are provided as stirring devices (5) in the annular disk reactor or disk-cage reactor (20). 28.The reactor as claimed in at least one of claims 15 to 27, wherein the longitudinal spars (14) are round or profiled. 29.The reactor as claimed in at least one of claims 15 to 28, wherein the longitudinal spars (14) are round and profiled. 30.The reactor as claimed in at least one of claims 15 to 29, wherein perforations are provided in the longitudinal spars (14) or hollow cylinders (12). 31.The reactor as claimed in at least one of claims 15 to 30, wherein geometrical mixing means, in particular annular disks, segments of annular disks, scoop-shaped profiles, scooping elements located on annular disks or on geometric parts or the like are provided as stirring elements (15). 32.The reactor as claimed in at least one of claims 15 to 31, wherein the mixing means used as stirring elements (15) are arranged perpendicularly or obliquely with identical inclination or different inclinations on the shaft (11), the hollow cylinder (12) or the support frame (14). 33.The reactor as claimed in at least one of claims 15 to 32, wherein the mixing means used as stirring elements (15) are arranged at equal or different distances from one another. 34.The reactor as claimed in at least one of claims 15 to 33, the mixing means used as stirring elements (15) are continuously smooth or provided with perforations (16). 35.The reactor as claimed in at least one of claims 15 to 34, wherein the mixing means used as stirring elements (15) are arranged inside, outside or inside and outside on the longitudinal spars (14) or the hollow cylinder (12). 36.The reactor as claimed in at least one of claims 15 to 35, wherein the mixing means used as stirring elements (15) comprise metal sheets, pieces of metal sheet, tubes, profiled rods, scooping elements or the like. 37.The reactor as claimed in at least one of claims 15 to 36, wherein ah annular disk reactor or disk-cage reactor (39) or an SSP (solid state polycondensation) is provided as end reactor downstream of the reactor (1). 38.The reactor as claimed in at least one of claims 15 to 37, wherein an annular disk reactor or disk-cage reactor (39) and an SSP (solid state polycondensation) is provided as end reactor downstream of the reactor (1). The invention relates to a method and a device for the continuous production of polymers. According to said method, monomers are initially obtained in a vertical reactor having a plurality of reaction zones (A, B,C), subsequently, prepolymers and then the desired polymer are obtained. At least one reaction zone of the reactor (1) is embodied as a disk cage reactor or a ring disk reactor.

Documents:

2214-KOLNP-2005-(12-12-2011)-FORM-27.pdf

2214-KOLNP-2005-FORM 27.pdf

2214-KOLNP-2005-FORM-27-1.1.pdf

2214-kolnp-2005-granted-abstract.pdf

2214-kolnp-2005-granted-claims.pdf

2214-kolnp-2005-granted-correspondence.pdf

2214-kolnp-2005-granted-description (complete).pdf

2214-kolnp-2005-granted-drawings.pdf

2214-kolnp-2005-granted-examination report.pdf

2214-kolnp-2005-granted-form 1.pdf

2214-kolnp-2005-granted-form 18.pdf

2214-kolnp-2005-granted-form 2.pdf

2214-kolnp-2005-granted-form 26.pdf

2214-kolnp-2005-granted-form 3.pdf

2214-kolnp-2005-granted-form 5.pdf

2214-kolnp-2005-granted-reply to examination report.pdf

2214-kolnp-2005-granted-specification.pdf

2214-kolnp-2005-granted-translated copy of priority document.pdf