Classifications

• • B—PERFORMING OPERATIONS; TRANSPORTING
  • B01—PHYSICAL OR CHEMICAL PROCESSES OR APPARATUS IN GENERAL
  • B01D—SEPARATION
  • B01D1/00—Evaporating
  • B01D1/22—Evaporating by bringing a thin layer of the liquid into contact with a heated surface
• • C—CHEMISTRY; METALLURGY
  • C08—ORGANIC MACROMOLECULAR COMPOUNDS; THEIR PREPARATION OR CHEMICAL WORKING-UP; COMPOSITIONS BASED THEREON
  • C08F—MACROMOLECULAR COMPOUNDS OBTAINED BY REACTIONS ONLY INVOLVING CARBON-TO-CARBON UNSATURATED BONDS
  • C08F6/00—Post-polymerisation treatments
  • C08F6/001—Removal of residual monomers by physical means
  • C08F6/003—Removal of residual monomers by physical means from polymer solutions, suspensions, dispersions or emulsions without recovery of the polymer therefrom
• • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
  • F28—HEAT EXCHANGE IN GENERAL
  • F28D—HEAT-EXCHANGE APPARATUS, NOT PROVIDED FOR IN ANOTHER SUBCLASS, IN WHICH THE HEAT-EXCHANGE MEDIA DO NOT COME INTO DIRECT CONTACT
  • F28D9/00—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall
  • F28D9/0012—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the apparatus having an annular form
  • F28D9/0018—Heat-exchange apparatus having stationary plate-like or laminated conduit assemblies for both heat-exchange media, the media being in contact with different sides of a conduit wall the apparatus having an annular form without any annular circulation of the heat exchange media
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S159/00—Concentrating evaporators
  • Y10S159/10—Organic
• • Y—GENERAL TAGGING OF NEW TECHNOLOGICAL DEVELOPMENTS; GENERAL TAGGING OF CROSS-SECTIONAL TECHNOLOGIES SPANNING OVER SEVERAL SECTIONS OF THE IPC; TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10—TECHNICAL SUBJECTS COVERED BY FORMER USPC
  • Y10S—TECHNICAL SUBJECTS COVERED BY FORMER USPC CROSS-REFERENCE ART COLLECTIONS [XRACs] AND DIGESTS
  • Y10S159/00—Concentrating evaporators
  • Y10S159/15—Special material

Definitions

• the invention relates to a device and a method for removing volatile constituents from polymers, in particular for evaporating volatile components from polymer solutions by indirect heat exchange.
• the device comprises at least one container with inlet for the polymer solution and outlet for the volatile components and a drain for the polymer freed from the volatile components, and a heat exchanger with a plurality of channels which form a heat exchange zone, the channels being a length of 1.0 to 40 cm, a constant height of 1.3 to 13 mm over their length and a width of 1 to 10 cm in the entrance area of the channels, and the width of the channels between their entrance and their exit is at least doubled.
• Removing volatile components from a polymer solution is one of the last process steps in the manufacture of many polymers.
• the volatiles to be removed can be either solvents or unpolymerized monomers.
• various variants for removing the volatile components from polymer solutions are known, in each of which the polymer solution is heated to a temperature above the evaporation temperature of the volatile constituents by means of a heat exchanger.
• drying devices e.g. Thin film evaporators, extruders and those with indirect heat exchange are described.
• EP-B-226204 discloses a method and a heat exchanger for removing volatile components from a polymer solution with at least 25% by weight polymer.
• the polymer solution is heated in a zone of indirect heat exchange consisting of a plurality of channels.
• the channels have a substantially uniform surface to volume ratio in the range of 0.158 to 1.97 mm "1 , a height of 1.27 to 12.7 mm, a width of 2.54 to 10.16 cm and a length
• the polymer solution is heated in the channel at a pressure of 2-200 bar to a temperature above the evaporation temperature of the volatile components but below the boiling point of the polymer.
• the residence time of the polymer solution in the channels is 5 to 120 seconds After heating, the solution is transferred to a chamber in which at least 25% of the volatiles outgas from the solution.
• the process reduces thermal damage by reducing the time the polymer is exposed to high temperatures
• the process has the disadvantage that a complete removal of the solvent is not possible in one step and furthermore arise on the outside of the heat exchanger hervols polymer deposits that carbonize over time and occasionally flake off, so that the solvent is removed
• Polymer is contaminated.
• EP-B-352 727 discloses a process for removing volatile constituents from polymer solutions by heating the polymer solution in a plurality of channels connected in parallel above the evaporation temperature of the volatile components.
• the ratio of heat exchange area to product volume flow is ⁇ 80m 2 / m 3 / h.
• the flow rate in the channels is ⁇ 0.5 mm / s and the residence time of the polymer solution in the channels is 120 to 200 seconds.
• This method also has the disadvantage that complete removal of the solvent is not possible in one step.
• polymer deposits that carbonize over time and occasionally flake off, so that the solvent-free polymer is contaminated.
• the invention relates to a device for removing volatile components from a polymer solution
• a device for removing volatile components from a polymer solution comprising at least one container which has an inlet for the polymer solution, an outlet for the volatile components and an outlet for the polymer solution freed from the volatile components, and a heat exchanger, which is arranged within the container, with a central receiving zone for the polymer solution, which is connected to the inlet of the container, a product zone for receiving the treated polymer solution, a heat exchanger body with a plurality of channels which form a heat exchange zone and which the receiving zone with the Connect the product zone, a heating means for heating the heat exchanger body and the channels, characterized in that the channels have a length of 1.0 to 40 cm, a height of 1.3 to 13 mm which is constant over their length and in the entrance area of the channels in the receiving zone a width of 1 to 10 cm, the width of the channels between their entrance and their exit to the product zone at least doubling.
• the channels preferably have a rectangular cross section and the width of the channels at the outlet is three times as large as the width of the channels at the inlet, the channels being widened continuously but according to any desired contour. - 4 -
• the channels widen parabolically.
• the width of the channels is kept constant at least up to half their length and then expands to at least twice the width, the expansion taking place continuously, but according to any contour, in particular not linearly.
• the channel shapes when the temperature is appropriately adapted, allow the width of the channels to be constant in the area where the polymer solution is heated and only to widen when the polymer solution has reached a temperature above the evaporation temperature of the volatile components, so that they are still in the Channels well out of the
• both the width and the height of the channels can widen towards the exit in the preferred manner.
• the heat exchanger of the device according to the invention preferably has at least 100 such channels. In particular, however, 200 to 100,000 of the channels are present in the heat exchanger.
• the heat exchanger is cylindrical
• the heat exchanger in the area of the outlets of the channels is preferably designed such that the individual channels abut one another laterally and / or on their upper and lower sides, so that there are no zones between the outputs of the channels in which polymer material can accumulate. This applies to both the cylindrical and any other configuration of the channels.
• the heat exchanger body has, in particular, a cuboid shape and is arranged below the receiving zone.
• the heat exchanger body is formed from a plurality of plate segments arranged one above the other or next to one another in planes, the plate segments being spaced apart in one plane, and their spacing and their lateral contour in the plane being the width of the channels and the thickness of the plate segments determines the height of the channels.
• the heat exchanger body is formed from a plurality of plates arranged one above the other or next to one another, which are separated from one another by spacers, the distance and the lateral contour of the spacers being the width of the channels and the thickness of the
• Spacers determine the height of the channels.
• the device is preferably made wholly or partially, in particular on the parts touched by the polymer solution, from a low-iron metal material which contains at most 10% by weight, preferably at most 5% by weight, of iron.
• the low-iron material is preferably tantalum or a low-iron nickel alloy and is selected in particular from the series Alloy, 59 (2.4605), Inconell 686 (2.4606), Alloy - B2, Alloy - B3, AUoy - B4, Hastelloy C-22, Hastelloy-C276 , Hastelloy-C4, preferably Alloy 59.
• the heat exchanger has any means known to the person skilled in the art for heating the channels to temperatures above the evaporation temperature of the volatile components. These means are e.g. Resistance heater or a pipe network for transporting a heat exchange liquid.
• the channels in the heat exchanger body are preferably inclined over their length by an angle to the horizontal and arranged to fall towards their exit, in particular they are arranged vertically.
• the receiving zone is arranged above the channels.
• the heating means for the heat exchanger are preferably designed as a multiplicity of pipelines which are guided transversely to the channels through the plate segments or through the plates and through which a heat exchanger liquid circulates.
• the invention further relates to a method for removing volatile components from a polymer solution with at least 40% by weight of polymer using the device according to the invention, the method comprising:
• the device and the method according to the invention can generally be used to remove volatile components from sensitive solids, in particular from thermoplastic polymers, elastomers, silicone polymers and lubricants with a high molecular weight and similar substances.
• thermoplastic polymers all include - 7 -
• Plastics that become fluid under the influence of pressure and temperature examples include polystyrene, polycarbonate, polyphenylene, polyurethane, polyamide, polyester, polyacrylate, polymethacrylate.
• the process is particularly suitable for degassing polycarbonate.
• the volatile components can be both unpolymerized monomers and solvents.
• a solvent frequently used in the production of thermoplastic polymers is, for example, methylene chloride or a mixture of methylene chloride and chlorobenzene.
• the polymer solutions contain at least 40% by weight of polymer.
• the molten polymer solution typically has a viscosity of 0.5 to 200 Pas.
• the polymer solution is in particular at a pressure of 1.5 to 50 bar abs., Preferably of 2 to 5 bar abs. pressed into the channels, flows through the channels of the heat exchanger and is heated to a temperature of preferably 250 to 350 ° C. At the outlet of the channels there is preferably a pressure which is below the saturation pressure of the volatile component at the respective temperature.
• the pressure in the product zone is preferably less than or equal to 10 5 Pa, in particular from 3,000 Pa to 10 5 Pa.
• the pressures upstream and downstream of the channels, the temperature in the channels and the shape of the channels are preferably selected such that the volatile components are completely separated from the polymer even within the channels.
• the pressure in the receiving zone and the temperature in the channels are chosen in particular so that the volatile components of the polymer solution in the channels are at least 95%, in particular at least 98%, preferably at least 99.5%, particularly preferably at least 99.8 % evaporate. - 8th -
• the residence time of the polymer solution in the channels is typically 5 to 120 seconds, preferably 80 to 120 seconds.
• the flow rate of the polymer solution is in particular from 0.0001 to 0.01 mm / s, preferably from 0.001 to 0.005 mm / s.
• the ratio of the heat exchange surface of the channels to the polymer solution volume flow is 5 to 75, preferably 15 to 50 m 2 / m 3 / h.
• Fig. 1 shows an apparatus according to the invention in longitudinal section.
• Fig. 3 shows a plane of the heat exchanger in cross section.
• Fig. 4 shows in longitudinal section through part of a heat exchanger how the levels of the heat exchanger lie one above the other.
• FIG. 5 shows a cross section through part of a variant of the heat exchanger of a device according to the invention constructed from plate segments arranged one above the other.
• Fig. 6 shows a longitudinal section through a variant of the invention
• FIG. 7 shows a longitudinal section along line AA in FIG. 6 in a simplified form to illustrate the guidance of the heat exchange medium through the tubes 13. - 9 -
• the apparatus according to the invention is shown in FIG. All units are made of Alloy 59 or have an Alloy 59 coating.
• the apparatus has a double jacket 16.
• the apparatus In the upper area the apparatus has an inlet 1 for the polymer solution and an outlet 3 for the volatile components.
• the polymer freed of volatile constituents In the lower region, the polymer freed of volatile constituents is drained off via outlet 2 with the aid of pump 24.
• the inlet 1 is tempered with a heat exchanger medium.
• the heat exchanger 31 Inside the double jacket 16 is the heat exchanger 31 with a central receiving zone 21 for receiving the polymer solution to be degassed.
• the receiving zone 21 is connected to the inlet 1.
• 200 channels 14 Around the receiving zone 21 are 200 channels 14 (see FIG. 2), which extend from the receiving zone to the periphery of the heat exchanger 31 and to the outlet 32 in the
• the polymer solution is pumped through a inlet 1 into the receiving zone 21 by a conventional pump (not shown).
• a conventional pump not shown
• Recording zone 21 is a cylindrical displacement body 10.
• the heat exchanger has means for heating the channels above the evaporation temperature of the volatile components.
• These means are a plurality of tubes 13 on the periphery or in the interior of the heat exchanger 31, which are connected to one another via the annular chamber 17.
• the tubes 13 are connected to the annular chamber 11, into which the hot heat exchanger oil is introduced through the line 4.
• the heat exchanger oil is discharged again from the heat exchanger through line 5.
• the tubes 13 are held together by end plates.
• the jacket 16 of the apparatus can be heated with a heat exchanger fluid. - 10 -
• a channel of the device according to the invention is shown schematically in longitudinal section in FIG.
• the entrance 23 has a rectangular cross section with a height of 2 mm and a width of 10 mm.
• the length of the channel is 110 mm.
• the width of the channel is constant 10 mm for the first 60 mm.
• the channel then widens so that its width at the exit 32 is 40 mm.
• the side walls
• 25 and 26 of the channel 14 are shaped like a parabola in the rear area
• FIG. 3 shows how the channels 14 according to the invention are arranged in a circular configuration around the receiving zone 21.
• the tubes 13 run through the holes 22 in the spacers 20.
• FIG 4 several channel levels are shown in longitudinal section one above the other.
• the channels 14 are formed by a plurality of spacers 20 and plates 19 arranged alternately one above the other, through which the tubes 13 run and which fix the spacers and the plates in their position.
• the arrangement shown here is suitable for a device with a vertical position of the channels 14.
• the receiving zone 21 is located above the channel inputs 23.
• the heat exchanger body 32 is formed by layers 37 of plate segments 36 arranged one above the other.
• the segments are arranged one above the other.
• the channels 36 are spaced apart from one another in a layer 37 and thereby form the width of the channels 14.
• the height of the channels 14 is defined by the thickness of the plate segments 36.
• Channels are heated by a heat exchanger fluid that circulates in lines 4, 13 and 5.
• the device enters the inlet 1 (FIG. 6), passes through the receiving zone 21 with the displacer 10 and is distributed over the channels 14.
• the solution flows downward in the channels 14 and is freed of volatile constituents by heating.
• the polymer melt leaves the channels 14 and drips down into the product zone 18 for further processing.
• the polymer is by means of
• the polycarbonate solution was pressed into channels 14 at a pressure of 3000 hPa and heated to 300 ° C. there. A pressure of 40 hPa was present in the product zone behind the channels.
• the residence time of the polymer in channels 14 was 100 seconds.
• the channels were 1 cm wide at the entrance 23 and 3 cm wide at the exit 32 and widened after half the channel length as shown in FIG. 2. All parts in contact with the product were made of Alloy 59 alloy.
• the pressures at the inlet 23 and outlet 32 of the channels 14 and the shape of the channels were chosen so that the volatile components completely or at least almost completely degas in the channels. That degassed -12-
• Polycarbonate had a chlorobenzene content (solvent) of only 400 ppm.

Landscapes

• Chemical & Material Sciences (AREA)
• Engineering & Computer Science (AREA)
• Chemical Kinetics & Catalysis (AREA)
• Thermal Sciences (AREA)
• Mechanical Engineering (AREA)
• Polymers & Plastics (AREA)
• Organic Chemistry (AREA)
• Physics & Mathematics (AREA)
• Health & Medical Sciences (AREA)
• Dispersion Chemistry (AREA)
• Medicinal Chemistry (AREA)
• General Engineering & Computer Science (AREA)
• Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)
• Heat-Exchange Devices With Radiators And Conduit Assemblies (AREA)
• Vaporization, Distillation, Condensation, Sublimation, And Cold Traps (AREA)
• Degasification And Air Bubble Elimination (AREA)
• Polymerisation Methods In General (AREA)

Applications Claiming Priority (3)

Publications (1)

Family

ID=7865248

Family Applications (1)

Country Status (9)

Families Citing this family (17)

Family Cites Families (5)

• 1998
  • 1998-04-21 DE DE19817678A patent/DE19817678A1/de not_active Withdrawn
• 1999
  • 1999-04-08 CN CN99805013A patent/CN1297367A/zh active Pending
  • 1999-04-08 KR KR1020007011638A patent/KR20010042864A/ko not_active Withdrawn
  • 1999-04-08 EP EP99915751A patent/EP1077753A1/de not_active Withdrawn
  • 1999-04-08 JP JP2000544413A patent/JP2002512266A/ja active Pending
  • 1999-04-08 US US09/673,225 patent/US6627040B1/en not_active Expired - Fee Related
  • 1999-04-08 AU AU34211/99A patent/AU3421199A/en not_active Abandoned
  • 1999-04-08 WO PCT/EP1999/002398 patent/WO1999054017A1/de not_active Ceased
  • 1999-04-09 TW TW088105629A patent/TW436495B/zh not_active IP Right Cessation

Non-Patent Citations (1)

Also Published As

Similar Documents

Legal Events