Classifications

• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/78—Preparation processes
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/78—Preparation processes
  • C08G63/785—Preparation processes characterised by the apparatus used
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/0053—Details of the reactor
  • B01J19/0066—Stirrers
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J19/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
  • B01J19/18—Stationary reactors having moving elements inside
• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01J—CHEMICAL OR PHYSICAL PROCESSES, e.g. CATALYSIS OR COLLOID CHEMISTRY; THEIR RELEVANT APPARATUS
  • B01J3/00—Processes of utilising sub-atmospheric or super-atmospheric pressure to effect chemical or physical change of matter; Apparatus therefor
  • B01J3/006—Processes utilising sub-atmospheric pressure; Apparatus therefor
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08G—MACROMOLECULAR COMPOUNDS OBTAINED OTHERWISE THAN BY REACTIONS ONLY INVOLVING UNSATURATED CARBON-TO-CARBON BONDS
  • C08G63/00—Macromolecular compounds obtained by reactions forming a carboxylic ester link in the main chain of the macromolecule
  • C08G63/02—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds
  • C08G63/12—Polyesters derived from hydroxycarboxylic acids or from polycarboxylic acids and polyhydroxy compounds derived from polycarboxylic acids and polyhydroxy compounds
  • C08G63/16—Dicarboxylic acids and dihydroxy compounds

Definitions

• the invention relates to a ner driving and a device for the continuous production of polyesters (PES) by esterification / transesterification of dicarboxylic acids or dicarboxylic acid esters with diols, preferably polyethylene terephthalate (PET), starting from terephthalic acid (PTA) or dimethyl terephthalate (DMT) and ethylene glycol (EG ), in at least one reaction stage, norpolycondensation of the ner / transesterification product under vacuum by means of a reaction stage consisting of a vertical reactor and polycondensation of the norpolycondensation product in at least one polycondensation stage.
• PET polyethylene terephthalate
• PTA terephthalic acid
• DMT dimethyl terephthalate
• EG ethylene glycol
• PTA or dimethyltherephthalate (DMT) and EG are used as raw materials for the continuous production of PET.
• PTA is mixed with EG and a catalyst solution to form a paste and a first reaction stage for esterification is given, in which the esterification takes place at atmospheric or superatmospheric pressure with elimination of water.
• DMT dimethyltherephthalate
• the DMT melt and the catalyst together with the EG are fed to a first reaction stage for the transesterification, in which the reaction takes place at atmospheric pressure with the elimination of methanol (MeOH).
• MeOH methanol
• the product stream of the esterification / TJ ⁇ est für is fed to a reaction stage for prepolycondensation, which is usually carried out under vacuum.
• the Product stream of prepolycondensation is introduced into a reaction stage for polycondensation.
• the polyester melt obtained is processed directly into fibers or chips.
• the conventional process for the production of PES consists of two stirring stages for esterification and prepolycondensation and a horizontal cascade reactor for polycondensation, which contains a chamber on the bottom side and a stirrer equipped with vertical perforated or ring disks on a horizontal shaft for the purpose of a defined surface generation.
• the disadvantages of this process can be seen in particular in the fact that in the cascade reactor with sufficiently high throughputs, comparatively high temperatures of 284 to 288 ° C., which are disadvantageous for the quality, occur.
• the vacuum applied in the first stirring stage of the prepolycondensation to avoid foaming and droplet flight (entrainment) is limited to p> 50 mbar.
• the viscosity of the prepolycondensation product is likewise limited to a range from 0.20 to 0.24 IV.
• Another disadvantage is the increased gas accumulation in the cascade reactor forming the polycondensation stage.
• the use of a horizontal cascade reactor instead of the second stirring stage for prepolycondensation allows a high flexibility of PES production at comparatively lower temperatures from 277 to 283 ° C in the cascade reactor for polycondensation and an increased viscosity of the prepolycondensation product from 0.27 to 0.31 IV as well as the best possibilities for increasing the Plant capacity (Schumann, Heinz-Dieter: Polyester producing plants; principles and technology. Landsberg / Lech: Verl. Moderne Industrie, 1996, pp. 27 to 33).
• the high investment costs for the operating equipment and the operating building remain disadvantageous.
• the reactor In its initial upper area, the reactor has an upwardly open spiral channel with product application on the wall side, which communicates from the outside inwards via a central overflow with a bottom-side stirred product sump, the channel bottom increasing continuously in the direction of flow, so that the depth of the product stream increases steadily decreases.
• the product stream is heated with the help of individual radiators, which are initially repeated at intervals, and optionally via the duct walls.
• the channel floor which rises in the direction of flow, prevents an independent system drainage in the direction of flow, with the result that residues form, quality deterioration or product losses occur, in particular in the event of operational accidents or when the production system is shut down.
• the operating vacuum is either restricted, the operating temperature is increased, the color quality of the product produced is reduced, or there is a risk of excessive vapor velocity and increased droplet formation which is critical for trouble-free condensation; this effect is additionally reinforced by locally concentrated radiators in the flow channel.
• US-A-5464590 discloses a standing polymerization reactor with a plurality of floors arranged vertically one above the other, each having two flow channels open at the top and an overflow weir at the respective channel end with subsequent floor recess for vertical product transfer in the form of a free-falling film on the subsequent floor.
• the channel has the shape of an approximately ring-shaped double loop, the first loop in each case being deflected into the second counter-rotating loop in a semicircular shape.
• the liquid polymer flows freely through the channels from top to bottom.
• the vapors flow between the trays to the center of the reactor and escape through central tray openings to the vapor outlet on the reactor cover.
• a low filling level on the floors and a heating restricted to the floor area mean a deficit in the residence time for the prepolycondensation of esterification products with restricted polymer grades from 4.5 to 7.5, with the result that either the number of floors or the dimensions of the reactor have to be increased.
• Another disadvantage is that reaction space is lost due to the installation of guide bodies and free falling film zones. Due to the horizontal arrangement of the Channel bottoms and the overflow weirs do not guarantee residue-free continuous operation of the reactor and / or its complete drainability.
• the object of the present invention is to carry out the prepolycondensation in one reaction stage in the process for producing PES described at the outset and at the same time to bring the viscosity of the prepolycondensation product to 0.24 to 0.26 IV at lower process temperatures of 268 to 275 ° C. in the vololycondensation stage and 276 to 282 ° C in the polycondensation stage and a lower vacuum of 7 to 18 mbar. Furthermore, foam formation and droplet flight should be easy to control.
• This object is achieved in that the esterification / transesterification product flowing into the reactor, in which a pressure of 10 to 40% of the diol equilibrium pressure of the prepolycondensation product leaving the reactor prevails, firstly in succession at least one first reaction zone formed from a channel flowed through with limited heating with a constant product height, then in the radially outer or radially inner ring channel at least one second reaction zone formed from an annular channel divided into several concentric ring channels, with constant product height successively through the ring channels to the outlet and then into a stirred one at the bottom the third reaction zone located in the reactor is passed.
• a pressure of 10 to 40% of the diol equilibrium pressure of the prepolycondensation product leaving the reactor prevails, firstly in succession at least one first reaction zone formed from a channel flowed through with limited heating with a constant product height, then in the radially outer or radially inner ring channel at least one second reaction zone formed from an annular channel divided into several concentric ring channels, with constant
• the total pressure of the reaction product at the bottom of the troughs of the first and second reaction zones resulting from the hydrostatic pressure and the operating pressure is smaller than the local diol equilibrium pressure of the polycondensation stage and is 5 to 80%, preferably 10 to 70%, of the diol equilibrium pressure.
• the following applies to the EG equilibrium pressure: p G L 4 ps, ⁇ [(DP) 2 -l] "1 , p s, ⁇ denoting the EG vapor pressure and DP denoting the degree of polymerization.
• the product height in the ring channels of the second reaction zone is lower by a factor of 2 to 3.5 than that in the trough of the first reaction zone.
• the vapors formed in the three reaction zones are usually drawn off from the reactor together.
• a preferred embodiment of the invention consists in feeding the vapors of the first reaction zone to a separating device for the entrained product droplets before they are combined with the vapors of the other two reaction zones.
• the foam and droplet problem can be controlled by this measure.
• the flow in the trough forming the first reaction zone can be regarded as turbulent due to the violent gas evolution up to about half of the flow path. With the decrease in gas formation and the increase in the viscosity of the product flow, a laminar flow then occurs at the latest in the last third of the flow path. According to the similarity theory of flows in open channels, the flow of the product stream in the ring channels of the second reaction zone is laminar. In order to avoid the formation of a faster core flow and a slower edge flow at the bottom and on the walls of the trough of the first reaction zone and the ring channels of the second reaction zone in the case of laminar flow, according to a further feature of the invention it is necessary to throttle the speed of the core flow or that to accelerate the edge flow.
• the product stream is passed in parallel in the same direction or in parallel in opposite directions through the ring channels of the second reaction stage.
• a heating register running in the flow direction is arranged in the channel of the first reaction zone for limited, controlled heating of the product flow, the pipes of which are held in chamber plates arranged transversely to the flow direction with a floor-free and / or wall-free passage.
• the axial velocity of the product flow is throttled in the free edge zones by these chamber plates and relatively accelerated in the area of the heating register and on the floor.
• the built-in flow in the subsequent laminar channel flows accelerates the slower edge and bottom speed and slows it down in the faster core flow.
• a closed Brüdensa melraum is attached above the trough of the first reaction zone, the outlet opening of which is connected to the separating device, preferably with a cyclone-like gas duct, for the entrained product droplets.
• a further feature according to the invention is to additionally arrange a drainage pipe or intermediate drainage openings at the ends of the gutter and / or ring channels in the rearmost dead corner at the deepest point of the floor in order to avoid an accumulation of residues.
• the bottom of the trough of the first reaction zone and / or that of the trough forming the ring channels of the second reaction zone is expediently inclined 0.5 to 6 °, 1 to 4 ° to the horizontal plane.
• the stirrer for the third reaction zone is a floor-level impeller, a finger, frame or drum stirrer, each with a vertical drive axis.
• the stirrer for the third reaction zone can alternatively be part of a turntable cascade or a cage reactor, each with a horizontal drive axis.
• the turntable cascade consists of perforated, ring or solid disks, with half of the inlet for the reaction product at the axial ends and the common outlet in the middle.
• an esterification product for prepolycondensation is fed via line 1 to the vertical reaction vessel 2 into the radially circumferential groove 3 forming the first reaction zone arranged therein.
• the gutter 3 there is a heating register 4, the tubes 5 of which are arranged concentrically, the gutter being closed at the top by a wall 7 concentrically extending between the radial outer gutter wall and the reactor vessel 2 to form a vapor collecting space 6.
• the product droplets entrained in the vapor collecting space 6 are separated in the cyclone-like separating device 8.
• the product leaving the channel 3 is fed in via an overflow pipe 9 at the beginning of an external ring channel 10 and then two further ring channels 11, 12, which form the first section 13 of the second reaction zone.
• the product After flowing through the ring channels 10, 11, 12, the product is discharged at the end of the inner ring channel 12 through an overflow pipe 14 and is introduced into the outer ring channel 15 of a channel comprising two further ring channels 16, 17 forming the second section 18 of the second reaction zone.
• Overflow pipe 19 derived and fed to the sump 22 which forms the third reaction zone and is stirred by means of an impeller 20 with a vertical drive axis 21.
• the vapors formed in the three reaction zones are passed outside via line 23.
• the prepolycondensation product is removed via line 24 from the sump 22 and fed to the polycondensation stage, not shown.

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• Chemical & Material Sciences (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Organic Chemistry (AREA)
• Health & Medical Sciences (AREA)
• Medicinal Chemistry (AREA)
• Polymers & Plastics (AREA)
• Polyesters Or Polycarbonates (AREA)

Priority Applications (7)

Applications Claiming Priority (2)

Publications (1)

Family

ID=32010184

Family Applications (1)

Country Status (13)

Cited By (1)

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Citations (3)

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• 2002
  • 2002-10-02 DE DE10246251A patent/DE10246251A1/de not_active Withdrawn
• 2003
  • 2003-09-19 WO PCT/EP2003/010444 patent/WO2004033526A1/de not_active Ceased
  • 2003-09-19 US US10/530,216 patent/US7244806B2/en not_active Expired - Lifetime
  • 2003-09-19 JP JP2004542361A patent/JP2006507377A/ja active Pending
  • 2003-09-19 AT AT03770944T patent/ATE291601T1/de not_active IP Right Cessation
  • 2003-09-19 DE DE50300388T patent/DE50300388D1/de not_active Expired - Lifetime
  • 2003-09-19 AU AU2003280336A patent/AU2003280336A1/en not_active Abandoned
  • 2003-09-19 EA EA200500489A patent/EA009719B1/ru not_active IP Right Cessation
  • 2003-09-19 EP EP03770944A patent/EP1478677B8/de not_active Expired - Lifetime
  • 2003-09-19 ES ES03770944T patent/ES2238068T3/es not_active Expired - Lifetime
  • 2003-09-19 KR KR1020047017443A patent/KR100962873B1/ko not_active Expired - Fee Related
  • 2003-09-23 TW TW092126220A patent/TWI263650B/zh not_active IP Right Cessation
  • 2003-09-26 CN CNB031601197A patent/CN1320024C/zh not_active Expired - Lifetime
• 2005
  • 2005-05-03 LT LT2005048A patent/LT5276B/lt not_active IP Right Cessation

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