EP1915404A1 - Procede de polymerisation anionique de styrene par pulverisation - Google Patents

Procede de polymerisation anionique de styrene par pulverisation

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Publication number
EP1915404A1
EP1915404A1 EP06764287A EP06764287A EP1915404A1 EP 1915404 A1 EP1915404 A1 EP 1915404A1 EP 06764287 A EP06764287 A EP 06764287A EP 06764287 A EP06764287 A EP 06764287A EP 1915404 A1 EP1915404 A1 EP 1915404A1
Authority
EP
European Patent Office
Prior art keywords
initiator
styrene
droplets
tower
melt
Prior art date
Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
Withdrawn
Application number
EP06764287A
Other languages
German (de)
English (en)
Inventor
Wolfgang Loth
Volker Seidl
Stefan Bruhns
Klaus-Dieter Hungenberg
Jürgen Koch
Christian Schade
Claudius Schwittay
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
BASF SE
Original Assignee
BASF SE
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Application filed by BASF SE filed Critical BASF SE
Publication of EP1915404A1 publication Critical patent/EP1915404A1/fr
Withdrawn legal-status Critical Current

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Classifications

    • 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
    • C08F112/00—Homopolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and at least one being terminated by an aromatic carbocyclic ring
    • C08F112/02—Monomers containing only one unsaturated aliphatic radical
    • C08F112/04—Monomers containing only one unsaturated aliphatic radical containing one ring
    • C08F112/06—Hydrocarbons
    • C08F112/08—Styrene

Definitions

  • the invention relates to a process for the continuous preparation of Styrolpolyme- ren by anionic spray polymerization, characterized in that
  • melt droplets collected at the base of the tower as a melt, wherein the melt has a monomer content of less than 1%, preferably below 0.1% ( ⁇ 1000 ppm), and is discharged by means of a suitable device.
  • the anionic polymerization of styrene proceeds with great positive heat of reaction and is therefore usually carried out in solution of a low boiler, which absorbs the heat of polymerization by the evaporative cooling.
  • a solvent USP 4,442,273, USP 4,883,846, USP 5,902,865
  • the polymers accumulate as a solution in a solvent (USP 4,442,273, USP 4,883,846, USP 5,902,865) and must be freed of solvent and optionally low molecular weight impurities such as monomers and oligomers via suitable degassing agents and be converted into a solid.
  • the prior art discloses the anionic polymerization of styrene in the case of an isothermal reaction under 100 ° C. This procedure leads to a solid polystyrene with relatively high residual monomer content. Before assembly, the polystyrene usually has to be melted and degassed. Alternatively, it is polymerized in solution, which leads to considerable expense in the subsequent solvent removal and work-up. The low reaction temperatures also lead in both cases to low space-time yields and high residence times, which make the process economically unattractive.
  • Object of the present invention was therefore to find a method that the o.g. Disadvantages not.
  • a process should be found which, with high space / time yields, provides a high purity polystyrene melt which is directly, i. can be further processed without a complex degassing.
  • the task is solved as follows.
  • the cooled monomer solution including Initiatorlö- solution is optionally heated to 30 to 50 0 C and sprayed or dripped so that small droplets of preferably 0.05 mm to 1 more preferably 0.1 to 0.4 mm are formed.
  • the monomers in the droplets are polymerized.
  • neither a solvent is added nor cooled in countercurrent.
  • the droplets thus heat up above the melting temperature of polystyrene.
  • the droplets are in liquid or molten form throughout the duration of the fall.
  • the droplets are caught in a melt lake.
  • the monomers can be implemented almost quantitatively.
  • Suitable styrene monomers are all anionically polymerizable vinyl polymers, such as, for example, styrene itself, ⁇ -methylstyrene, t-butylstyrene, vinyltoluene and divinylbenzene and mixtures thereof.
  • the amount of the comonomers is usually 1 to 99, preferably 5 to 70 and more preferably 5 to 50 wt .-% based on styrene.
  • the process according to the invention produces rubber-free polystyrene (GPPS, general purpose polystyrene).
  • GPPS general purpose polystyrene
  • PSaMS styrene- ⁇ -methylstyrene copolymers having an ⁇ -methylstyrene content of e.g. 1 to 50 wt .-% with the inventive method produce.
  • the weight-average molecular weight M w of the polymer produced according to the invention is generally from 10,000 to 1,000,000, preferably from 50 to 500,000 and in particular from 100,000 to 400,000 g / mol.
  • Suitable initiators are alkali metal compounds selected from hydrides, amides, carboxyls, aryls, arylalkylenes and alkyls of the alkali metals, or mixtures thereof. It is understood that various alkali metal compounds can also be used. The preparation of the alkali metal compounds is known or the compounds are commercially available.
  • alkali metal organyls are suitable. These include alkali metal aryls and alkyls.
  • Alkali metal alkyls are compounds of alkanes, alkenes and alkynes having 1 to 10 C atoms, for example ethyl, propyl, isopropyl, n-butyl, sec-butyl, tert-butyl, hexamethylenedio, butadienyl, isoprenyl Lithium, sodium or potassium, or multifunctional compounds such as 1, 4-dilithiobutane or 1, 4-dilithio-2-butene.
  • Alkali metal alkyls are particularly well suited for the preparation of the styrene matrix. for the polymerization of polystyrene preferably sec-butyllithium use.
  • Suitable alkali metal aryls are, for example, phenyl lithium and phenyl potassium, and the multifunctional compound 1, 4-dilithiobenzene.
  • oligomeric or polymeric compounds such as polystyryl lithium or sodium, which can be obtained, for example, by mixing sec-butyllithium and styrene, and then adding TIBA. Furthermore, it is also possible to use diphenylhexyl lithium or potassium. Such adducts of the initiator to the monomer are also referred to as pre-activation. The pre-activation causes a faster and better controlled start of the reaction after spraying.
  • Suitable alkali metal hydrides are, in particular, lithium hydride, sodium hydride or potassium hydride.
  • initiators it is also possible to use reaction products, so-called macroinitiators, of the alkali metal or alkaline earth metal compounds with butadiene (for example polybutadienyllithium) or styrene-butadiene block structure-based macroinitiators.
  • butadiene for example polybutadienyllithium
  • styrene-butadiene block structure-based macroinitiators for example polybutadienyllithium
  • alkali alkoxides can be used to modify the reactivity and stability of the anions.
  • the required amount of alkali metal compound depends i.a. according to the desired molecular weight (molecular weight) of the polymer to be produced, the type and amount of the aluminum or magnesium organyl used - if it is also used - and the polymerization temperature. In general, 0.00001 to 1, preferably 0.0001 to 0.1 and particularly preferably 0.0001 to 0.01 mol% of alkali metal compound, based on the total amount of the monomers used.
  • Organylaluminum in particular those of the formula R3-AI can be used to advertising, where the radicals R are independently hydrogen, halogen, Ci -2 o-alkyl, C6-2o-aryl or C7-2-o arylalkyl.
  • R are independently hydrogen, halogen, Ci -2 o-alkyl, C6-2o-aryl or C7-2-o arylalkyl.
  • aluminum organyl aluminum trialkyls are preferably used.
  • the alkyl radicals may be the same, e.g. Trimethylaluminum (TMA), triethylaluminum (TEA), triisobutylaluminum (TIBA), tri-n-butylaluminum, tri-iso-propylaluminum, tri-n-hexylaluminum, or various, e.g. Ethyl-di-iso-butyl-aluminum. It is also possible to use aluminum dialkyls such as di-isobutylaluminum hydride (DiBAH).
  • DIBAH di-isobutylaluminum hydride
  • Aluminum organyls which can also be used are those which are formed by partial or complete reaction of alkyl, arylalkyl or arylaluminum compounds with water (hydrolysis), alcohols (alcoholysis), amines (aminolysis) or oxygen (oxidation), or the alkoxide , Thiolate, amide, imide or phosphite Bear groups. Hydrolysis gives aluminoxanes. Suitable aluminoxanes are, for example, methylaluminoxane, isobutylated methylaluminoxane, isobutylaluminoxane and tetraisobutyldialuminoxane.
  • reaction accelerator for the anionic polymerization inert, polar substances such as ethers, preferably cyclic ethers, e.g. Tetrahydrofuran or Crown 16-ether can be used. They cause a stronger dissociation of the aggregated anionic species. This causes a dramatic increase in the reaction rate over the proportion of active ("awake” as opposed to “dormant") molecules both at the start and during the polymerization.
  • the polymerization is carried out without a solvent.
  • the choice of solvent also depends on the alkali metal compound used. Preference is given to choosing alkali metal compound and solvent such that the alkali metal compound dissolves at least partially in the solvent.
  • solvents are used which preferably have a lower boiling point than the monomer and provide by evaporation for targeted heat removal in the droplet.
  • the solvents used are typically C3 to Ce alkanes or cycloalkanes such as cyclohexane, methylcyclohexane or hexane or tedrahydrofuran.
  • mineral oils such as white oil can be used, which have a low vapor pressure and preferably remain in the polymer.
  • additives such as stabilizers, flow aids, flame retardants, blowing agents, fillers, etc.
  • Additives which do not or only insignificantly influence the anionic polymerization can be added to the mixture before spraying.
  • An example of an adjuvant that can be added before spraying is white oil.
  • the mixture of monomer and initiator takes place by means of dynamic or preferably static mixing devices.
  • the static mixers have the advantage that they are less expensive and less susceptible.
  • the two components styrene and initiator at temperatures ⁇ 10 0 C, preferably ⁇ 0 0 C, in a static mixer with a minimum flow rate expressed as Reynolds number (Re> 50) at a shear rate> 100 1 / s and a maximum residence time of ⁇ 1 s mixed in the mixing section.
  • Re> 50 Reynolds number
  • the shear stress on the pipe wall caused by the flow is not great enough and deposits are formed which grow out and consequently change to a closure / breakthrough and thus to an unsteady one Conduct behavior.
  • the design of the static mixer must be capable of sufficiently homogenizing streams of widely differing volumes in the correspondingly short time, since after the spraying no concentration balance between the compartments (droplets) is possible and small differences in concentration lead to dramatic differences in the resulting polymer molecular weight.
  • Split and Recombine mixer the expert as "Kenics or Sulzer mixer type" known and both for large and for small throughputs suitable, eg in the laboratory, so-called interdigital or interlaminator mixers (see: Hessel et al., AIChE J. 49 (2003) 3, pp. 566-577; Lob et al., Preprints of 11th Europ. Conf. on Mixing, Bamberg, 14-17-Oct. 2003, pp. 253-260).
  • the supply of the mixture to the spray tower is done to avoid premature polymerization start and consequent tendency to clog the Sprüht. Drop unit in cooled pipe.
  • the mixture is cooled to temperatures below 10 0 C and more preferably below 0 0 C.
  • the dispersion in the tower and generating the droplets is usually done with
  • EP-A-1 424 346 and in particular EP-A 05 / 010325.8 describe spray nozzles with which droplets having the desired size distribution can be realized.
  • the reactive mixing can be done by dripping, whereby both the "vibrating nozzle" and a liquid-defined oscillation of defined frequency in the kHz range can be used for drop formation
  • a preferred but non-limiting method of dripping is described in US-A 5,269,980.
  • the droplets formed have an average drop size of preferably 0.05 to 1 mm and particularly preferably 0.1 to 0.4 mm.
  • the dripping has the advantage over the spray that it leads to a homogeneous and narrow droplet size distribution.
  • the narrow droplet size distribution in turn facilitates the controlled polymerization in the spray tower.
  • with the dripping can be an efficient and process-capable polymerization process for polystyrene realize.
  • the droplets formed which initially have low temperatures (about 0 to 10 0 C), meet when entering the tower on inert gas, which has a temperature of 80 to 180, preferably 100 to 140 0 C. Due to the large surface / volume ratio and the small diameter, the drops reach a temperature near the gas temperature almost instantaneously.
  • the inert gas can be passed to the falling drops in cocurrent or countercurrent.
  • the DC principle is advantageous for the swarm behavior of the droplets and thus for avoiding collisions, uncontrolled aggregation and deposit formation in the tower.
  • the temperature increase is limited by the evaporation of monomers and auxiliaries.
  • the countercurrent principle leads to a longer mean residence time of the droplets in the tower and can absorb more heat at the end of the drop distance / reaction, but is known for its difficulties of deposit formation from spray drying.
  • the process is operated in cocurrent of droplets and inert gas.
  • the polymerization after starting within a few seconds (usually less than 20, preferably less than 10 seconds) with release tion of the heat of polymerization and evaporation of monomer and optionally solvent to the end point from.
  • the endpoint is determined by depletion of monomer and eventual death of the active anions at high temperatures.
  • a special break-off agent can be metered into the melt in the outlet of the tower.
  • the termination of the living anions takes place by elimination reaction or by protonation upon discharge and shaping / granulation by traces of protic substances, e.g. Water, alcohols or carbon dioxide.
  • the temperature profile of the gas phase and the drop on the way through the tower is determined by the feed temperature of the mixture (feed), the temperature of the gas phase at entry, the oil jacket temperature (little influence, rather “active insulation”), the mass flows, the pressure level in the tower , the drop size, the evaporation of monomer and optional solvent and the tower geometry due to the high heat of polymerization allows the temperature of the drops increase rapidly.
  • the drops already have temperatures greater than 110, preferably greater than 150 0 C.
  • the highest temperatures occur: the drops on the feet, which are finally caught in a melt lake.
  • they have a maximum temperature of 300 ° C., preferably 250 ° C., and more preferably 220 ° C. If the temperatures are too high, discoloration occurs and premature chain termination occurs. The consequence of the latter is the undesirable increase in the residual monomer content.
  • the temperature in the drops can preferably be controlled by the droplet size. Small droplets can better dissipate the heat of reaction over the relatively large surface area by evaporation. In large drops local overheating takes place. Bursting and deformation of the polymer droplet formed are the result.
  • the mean droplet size is therefore preferably in the o.g. Area.
  • the circulating gas withdrawn from the tower which typically contains 5-30%, preferably 10 to 15%, of the constituents which can be evaporated via the evaporative cooling, is usually conducted via a particle separator (eg cyclone) and a scrubber.
  • a particle separator eg cyclone
  • the recycle gas is preferably cooled to below 70 0 C and more preferably below 50 0 C via a quench circuit and condensed out in order to "discharge" the gas stream and unwanted (side) reactions, such as polymerization of the condensed monomer to avoid - the.
  • the quench liquid which consists essentially of the condensed monomer, is added with small amounts of a protic, high boiling substance such as stearyl alcohol.
  • the recycled polymer which has been freed of reactive polymer and depleted of monomer is recompressed and fed again to the tower at room temperature.
  • the quenched monomer is freed from the trace of the protic, high-boiling substance by distillation or adsorption to the monomer feed of the tower. Alternatively, the remaining amount of the protic, high-boiling substance can be compensated ("run over") by a higher initiator dosage.
  • the melt had polystyrene having a weight-average molecular weight of 220,000 g / mol.
  • the HPLC analysis gave a residual styrene content of 300 ppm.

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  • Chemical & Material Sciences (AREA)
  • Health & Medical Sciences (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • Medicinal Chemistry (AREA)
  • Polymers & Plastics (AREA)
  • Organic Chemistry (AREA)
  • Addition Polymer Or Copolymer, Post-Treatments, Or Chemical Modifications (AREA)

Abstract

L'invention concerne un procédé permettant de produire en continu des polymères styrénique par polymérisation anionique par pulvérisation, qui se caractérise en ce que: i) le styrène et la solution amorceuse sont mélangés dans un mélangeur dynamique ou statique et sont ensuite pulvérisés; ii) les gouttelettes formées pendant la précipitation libre dans la tour à priller passent de l'état de monomères liquides à l'état de polymères fondus; iii) les gouttelettes en fusion sont recueillies au pied de la tour sous forme de matière fondue, ladite matière fondue présentant une teneur en monomères inférieure à 1 %, de préférence inférieure à 0,1 % (< 1.000 ppm). Ladite matière fondue est ensuite extraite au moyen d'un dispositif approprié.
EP06764287A 2005-08-09 2006-08-01 Procede de polymerisation anionique de styrene par pulverisation Withdrawn EP1915404A1 (fr)

Applications Claiming Priority (2)

Application Number Priority Date Filing Date Title
DE102005038037A DE102005038037A1 (de) 2005-08-09 2005-08-09 Verfahren zur anionischen Sprühpolymerisation von Styrol
PCT/EP2006/064924 WO2007017420A1 (fr) 2005-08-09 2006-08-01 Procede de polymerisation anionique de styrene par pulverisation

Publications (1)

Publication Number Publication Date
EP1915404A1 true EP1915404A1 (fr) 2008-04-30

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ID=37000148

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Application Number Title Priority Date Filing Date
EP06764287A Withdrawn EP1915404A1 (fr) 2005-08-09 2006-08-01 Procede de polymerisation anionique de styrene par pulverisation

Country Status (4)

Country Link
US (1) US20100168348A1 (fr)
EP (1) EP1915404A1 (fr)
DE (1) DE102005038037A1 (fr)
WO (1) WO2007017420A1 (fr)

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
SG11201408406QA (en) * 2012-06-26 2015-03-30 Styrolution Europ Gmbh Method for producing polymers of vinyl aromatics, as well as vinyl aromatic-diene block copolymers

Family Cites Families (2)

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Publication number Priority date Publication date Assignee Title
US5717040A (en) * 1993-08-16 1998-02-10 Basf Aktiengesellschaft Continuous process for polymerizing anionically polymerizable vinyl compounds
US5587438A (en) * 1995-05-31 1996-12-24 Shell Oil Company Process for preparing styrene polymers

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
See references of WO2007017420A1 *

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Publication number Publication date
DE102005038037A1 (de) 2007-02-15
WO2007017420A1 (fr) 2007-02-15
US20100168348A1 (en) 2010-07-01

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