WO2011073132A1 - Procédé de préparation de polymère halogéné et dispositif de mise en oeuvre associé - Google Patents

Procédé de préparation de polymère halogéné et dispositif de mise en oeuvre associé Download PDF

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Publication number
WO2011073132A1
WO2011073132A1 PCT/EP2010/069491 EP2010069491W WO2011073132A1 WO 2011073132 A1 WO2011073132 A1 WO 2011073132A1 EP 2010069491 W EP2010069491 W EP 2010069491W WO 2011073132 A1 WO2011073132 A1 WO 2011073132A1
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polymer
monomer
reactor
stream
halogenated
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PCT/EP2010/069491
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English (en)
Inventor
Manuel De Francisco
Ivan Claeys
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Solvay Sa
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Priority to EP10788083A priority Critical patent/EP2513169A1/fr
Publication of WO2011073132A1 publication Critical patent/WO2011073132A1/fr

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    • 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
    • C08F14/00—Homopolymers and copolymers 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 a halogen
    • 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
    • B01J19/1862—Stationary reactors having moving elements inside placed in series
    • 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
    • B01J19/20—Stationary reactors having moving elements inside in the form of helices, e.g. screw reactors
    • 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
    • B01J19/24—Stationary reactors without moving elements inside
    • B01J19/2415—Tubular reactors
    • B01J19/242—Tubular reactors in series
    • 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
    • B01J3/008—Processes carried out under supercritical conditions
    • 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
    • C08F14/00—Homopolymers and copolymers 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 a halogen
    • C08F14/02—Monomers containing chlorine
    • C08F14/04—Monomers containing two carbon atoms
    • C08F14/06—Vinyl chloride
    • 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
    • C08F2/00—Processes of polymerisation
    • C08F2/04—Polymerisation in solution
    • 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
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00002—Chemical plants
    • B01J2219/00027—Process aspects
    • B01J2219/00033—Continuous processes
    • 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
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00049—Controlling or regulating processes
    • B01J2219/00051—Controlling the temperature
    • B01J2219/00074—Controlling the temperature by indirect heating or cooling employing heat exchange fluids
    • B01J2219/00087—Controlling the temperature by indirect heating or cooling employing heat exchange fluids with heat exchange elements outside the reactor
    • B01J2219/00094—Jackets
    • 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
    • B01J2219/00—Chemical, physical or physico-chemical processes in general; Their relevant apparatus
    • B01J2219/00049—Controlling or regulating processes
    • B01J2219/00051—Controlling the temperature
    • B01J2219/00159—Controlling the temperature controlling multiple zones along the direction of flow, e.g. pre-heating and after-cooling
    • 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
    • Y02—TECHNOLOGIES OR APPLICATIONS FOR MITIGATION OR ADAPTATION AGAINST CLIMATE CHANGE
    • Y02P—CLIMATE CHANGE MITIGATION TECHNOLOGIES IN THE PRODUCTION OR PROCESSING OF GOODS
    • Y02P20/00—Technologies relating to chemical industry
    • Y02P20/50—Improvements relating to the production of bulk chemicals
    • Y02P20/54—Improvements relating to the production of bulk chemicals using solvents, e.g. supercritical solvents or ionic liquids

Definitions

  • the present invention relates to a process for preparing halogenated polymers and to a device for the implementation thereof.
  • Liquid or supercritical carbon dioxide (also referred to more simply as “L/SC-CO 2 " in the present description) constitutes an advantageous medium for the polymerization of halogenated monomers, in particular vinyl and vinylidene halides.
  • L/SC-CO 2 is readily accessible, non-flammable, non-toxic and inexpensive, it is chemically inert during the synthesis.
  • SC-CO 2 also constitutes a good solvent for these monomers and a poor solvent for the synthesized polymers. The synthesized polymer is therefore recovered by precipitation in the form of particles, often extremely fine particles, from which the residual monomer is easy to remove.
  • the polymer obtained in L/SC-CO 2 is not contaminated by residues of these compounds and has a very high purity.
  • L/SC-CO 2 as main constituent of the polymerization medium makes it possible to avoid the conventional use of large amounts of demineralized water and, as a consequence, the consumption of large amounts of steam (or other forms of energy) for drying the polymer.
  • L/SC-CO 2 as main constituent of the polymerization medium of halogenated monomers has however one drawback linked to the considerable amount of energy necessary for reheating the carbon dioxide and the unreacted monomer, which are expanded on leaving the polymerization reactor, in order to effectively separate the solid polymer therefrom.
  • the objective of the present invention is to overcome this drawback by proposing, mainly, a novel continuous process for preparing halogenated polymers in a medium comprising L/SC-C0 2 .
  • the invention relates to a continuous process for preparing a halogenated polymer comprising a step of polymerization of at least one halogenated monomer in a medium comprising carbon dioxide in the liquid or supercritical state (L/SC-CO 2 ), in at least one pressurized reactor, said process being characterized in that it comprises at least :
  • said continuous process being characterized also by the fact that the reheating (3), applied to the expanded suspension, is combined with a recovery of the cold energy generated by the expansion.
  • continuous process is understood to mean, in the present description, a process in which the feeding with carbon dioxide, with monomers, with initiators and optional additives and the drawing-off of the contents of the reactor are carried out continuously.
  • the continuous process according to the invention is such that the control of the feeding operations, of the drawing-off and of the other polymerization conditions ensures stable operating conditions in the reactor.
  • the terms "monomer”, “polymer”, “initiator”, “additive”, “reactor”, “expansion”, “recompression”, “reheating", “first stream” and “second stream” are used without distinction in the singular and in the plural.
  • the polymerization step of the process according to the invention is carried out in a medium that is advantageously inert with respect to the halogenated monomers, comprising carbon dioxide in the liquid state (L-C0 2 ) or supercritical state (SC-CO 2 ).
  • the term "medium” is understood to mean the contents of the reactor with the exception of the halogenated monomer introduced and the halogenated polymer formed.
  • the medium in which the polymerization step of the process according to the invention is carried out may comprise other solvents of the halogenated monomers. These other solvents are generally chosen from those which do not generate an excessive amount of chain transfer reactions.
  • the temperature in the reactor is at least -60°C, preferably at least 0°C.
  • the temperature is at most 200°C, preferably at most 150°C.
  • the temperature in the reactor is advantageously at least 32°C, preferably at least 40°C. Still in this case, the temperature is advantageously at most 100°C, preferably at most 85°C.
  • the pressure in the reactor is at least 0.5 MPa, preferably at least 4 MPa.
  • the pressure is at most 100 MPa, preferably at most 50 MPa.
  • the pressure in the reactor is advantageously at least 4.5 MPa, preferably at least 8 MPa.
  • the pressure is advantageously at most 40 MPa, preferably at most 25 MPa.
  • the density of the medium in the reactor is at least 500 kg/m 3 , preferably at least 600 kg/m 3 .
  • the density of the medium in the reactor is at most 1200 kg/m 3 , preferably at most 1000 kg/m 3 .
  • polymerization of at least one halogenated monomer is understood to mean both the homopolymerization of a halogenated monomer and its copolymer ization with one or more other ethylenically unsaturated monomers, for the purpose of obtaining halogenated polymers.
  • halogenated polymer is understood to mean both homopolymers and copolymers of halogenated monomers. Among these, mention in particular may be made of the following : homopolymers of halogenated monomers, such as vinyl chloride and vinylidene chloride ; vinyl fluoride and vinylidene fluoride ; trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene and hexafluoropropylene ; fluoroacrylates ; fluorinated vinyl ethers, for example perfluorinated vinyl ethers bearing perfluoroalkyl groups containing 1 to 6 carbon atoms.
  • homopolymers of halogenated monomers such as vinyl chloride and vinylidene chloride ; vinyl fluoride and vinylidene fluoride ; trifluoroethylene, tetrafluoroethylene, chlorotrifluoroethylene and hexafluoropropylene ; fluoroacrylates ; fluorinated vinyl ether
  • halogenated monomers form together and the copolymers of one or more of these halogenated monomers with another ethylenically unsaturated monomer such as olefins, for example ethylene, propylene ; styrene derivatives and styrene ; halogenated olefins ; vinyl ethers ; vinyl esters such as for example vinyl acetate ; acrylic acids, esters, nitriles and amides and methacrylic acids, esters, nitriles and amides.
  • olefins for example ethylene, propylene
  • styrene derivatives and styrene halogenated olefins
  • vinyl ethers vinyl esters such as for example vinyl acetate ; acrylic acids, esters, nitriles and amides and methacrylic acids, esters, nitriles and amides.
  • the process according to the invention is characterized in that the halogenated polymer obtained is a chlorine-containing polymer.
  • chlorine-containing polymer is understood to mean both homopolymers and copolymers of chlorine-containing monomers. Among these, mention in particular may be made of the following : homopolymers of chlorinated monomers, such as chloroolefms, for example vinyl chloride and vinylidene chloride ; chloroacrylates and chlorinated vinyl ethers, for example perchlorinated vinyl ethers bearing perchloroalkyl groups containing 1 to 6 carbon atoms.
  • chlorinated monomers such as chloroolefms, for example vinyl chloride and vinylidene chloride
  • chloroacrylates and chlorinated vinyl ethers for example perchlorinated vinyl ethers bearing perchloroalkyl groups containing 1 to 6 carbon atoms.
  • these chlorine-containing monomers form together, such as for example copolymers of vinylidene chloride with another chlorinated monomer as defined above, and copolymers of one or more of the abovementioned chlorine-containing monomers with another ethylenically unsaturated monomer such as olefins, for example ethylene, propylene ; styrene derivatives and styrene ; halogenated olefins ; vinyl ethers ; vinyl esters such as for example vinyl acetate ; acrylic acids, esters, nitriles and amides and methacrylic acids, esters, nitriles and amides.
  • olefins for example ethylene, propylene
  • styrene derivatives and styrene halogenated olefins
  • vinyl ethers vinyl esters such as for example vinyl acetate ; acrylic acids, esters, nitriles and amides and methacrylic
  • the process according to the invention is characterized in that the halogenated polymer obtained is a vinyl chloride polymer.
  • vinyl chloride polymer is understood to mean both homopolymers of vinyl chloride and its copolymers with other ethylenically unsaturated monomers, whether these are halogenated (chloroolefms, for example vinylidene chloride ; chloroacrylates ; chlorinated vinyl ethers such as for example perchlorinated vinyl ethers bearing perchloroalkyl groups containing 1 to 6 carbon atoms) or not halogenated (olefins such as for example ethylene, propylene ; styrene derivatives and styrene ; vinyl ethers ; vinyl esters such as for example vinyl acetate ; acrylic acids, esters, nitriles and amides ; methacrylic acids, esters, nitriles and amides).
  • copolymers of vinyl chloride with a halogenated or non-halogenated comonomer advantageously containing at least 50 %, preferably at least 60 %, particularly preferably at least 70 % and very particularly preferably at least 85 % by weight of monomeric units derived from vinyl chloride are particularly preferred.
  • Vinyl chloride homopolymers and copolymers of vinyl chloride with vinyl acetate are very particularly preferred. Vinyl chloride homopolymers are truly very particularly preferred.
  • the polymerization step of the process according to the invention may be carried out according to any technique compatible with the medium comprising L/SC-CO 2 in which this step is conducted.
  • the polymerization of the halogenated monomer may be carried out by virtue of the action of radical initiators, of ionizing radiation, of Friedel-Crafts type catalysts, of Ziegler type catalysts, etc.
  • the polymerization step is carried out by radical means and customarily involves the use of one or more initiators, the nature, number and concentration of which may also be chosen according to the requirements.
  • initiators useful within the context of the present invention it is possible to use any appropriate radical initiator, in particular an organic radical initiator.
  • the polymerization step is preferably carried out in the presence of an organic radical initiator.
  • a support or of a solvent can also be envisaged for promoting the dispersion of the initiator in the polymerization medium.
  • supports that can be envisaged for this purpose, mention may be made of silicas, silica gels, aluminas and other metal oxides, such as titanium oxide.
  • solvent mention may for example be made of toluene, alcohols such as methanol, ethanol and isopropanol and hydrocarbons such as pentane, hexane and eye lo hexane.
  • the initiator that can be used according to the invention may be chosen for example from the following : peroxides, such as dimethyl peroxydicarbonate, diethyl peroxydicarbonate, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, diacetyl peroxydicarbonate, dicyclohexyl peroxydicarbonate, di(2-ethylhexyl) peroxydicarbonate, t-butyl peroxyisopropylcarbonate, t-butyl peroxy-n-decanoate, t-butyl peroxyacetate, 1,1,3,3-tetramethylbutyl
  • peroxides such as dimethyl peroxydicarbonate, diethyl peroxydicarbonate, di-n-propyl peroxydicarbonate, diisopropyl peroxydicarbonate, diacetyl peroxydicarbonate, dicyclohexyl peroxydicarbon
  • diacyl peroxides such as diacetyl peroxide, di-n-propionyl peroxide, diisobutyryl peroxide, dibenzoyl peroxide, diisobutanoyl peroxide, dioctanoyl peroxide, dilauroyl peroxide, dicumyl peroxide, di-t-amyl peroxide, t-butyl per-2- ethylhexanoate, t-butyl peroxymaleate, cumyl peroxyneodecanoate and t-amyl peroxyneodecanoate, cumene hydroperoxide, pinane hydroperoxide and
  • nitriles such as 2,2'-azobis(methoxy-2,4- dimethylvaleronitrile) and 2,2'-azobis(2,4-dimethylvaleronitrile) ; and similar compounds.
  • Preferred initiators are peroxides with a short half-life, for example diacyl peroxides, such as diacetyl peroxide, di-n-propionyl peroxide and diisobutyryl peroxide ; and also 1,1,3,3-tetramethylbutyl peroxymethoxyacetate, 2,2-bis(2,2- dimethylpropanolperoxy)-4-methylpentane, diisobutanoyl peroxide, cumyl peroxyneodecanoate and t-amyl peroxyneodecanoate.
  • diacyl peroxides such as diacetyl peroxide, di-n-propionyl peroxide and diisobutyryl peroxide ; and also 1,1,3,3-tetramethylbutyl peroxymethoxyacetate, 2,2-bis(2,2- dimethylpropanolperoxy)-4-methylpentane, diisobutanoyl peroxide, cumyl peroxyne
  • the concentration of initiators for the polymerization step is the concentration of initiators for the polymerization step.
  • the polymerization step of the process according to the present invention may be optionally carried out in the presence of one or more surfactants or one or more dispersants. Any suitable surfactant or dispersant known to those skilled in the art may be employed.
  • the polymerization step of the process according to the invention may optionally be carried out in the presence of additives other than the
  • additives for improving the implementation of the process and/or the characteristics of the resulting polymer.
  • additives are chain transfer agents, anti-crust agents, antistatic agents and cosolvents.
  • the polymerization step of the process according to the invention has an exothermic character most of the time and may be carried out in any type of suitable continuous reactor, as long as it withstands the high temperatures and pressures needed for carrying out the process.
  • Use may be made of a single reactor or of several reactors connected in series.
  • the reactors that can be used may be chosen for example from continuous mechanically stirred tank reactors and tubular reactors. In the case of continuous mechanically stirred tank reactors, advantageously several thereof are used, connected in series. In the case of tubular reactors, advantageously a single one thereof is used.
  • These reactors may advantageously be equipped with a heating system and/or with a cooling system for controlling the temperature.
  • Tubular reactors are preferred for carrying out the process according to the invention and, among the latter, tubular reactors with piston flow (“plug-flow" tubular reactors).
  • tubular reactor is understood to mean a reactor comprising an elongated tube, inside which the reaction mixture circulates, the heat exchange necessary for thermal control taking place across the wall of the tube, for example by means of a jacket inside which a heat -transfer fluid (water) circulates, generally counter-current.
  • the elongated tube may be constituted of a plurality of straight segments joined together by 180° bends, together forming a compact assembly.
  • the polymerization step of the process according to the invention is advantageously carried out so that the average residence time of the reaction medium in the reactor is between 5 and 60 minutes, preferably between 10 and 35 minutes. Frequently, from 20 to 90 % and, more often, from 40 to 80 % by weight of the monomer are polymerized in the reactor. In other words, frequently, from 10 to 80 %, more often from 20 to 60 % by weight of monomer are not converted to polymer. This unconverted monomer should, preferably, be recycled for the economics of the process.
  • the degree of conversion of the monomer to polymer is in particular governed by the choice of the temperature and pressure and by the choice of the nature and concentration of the initiator.
  • the reactor is advantageously fed at least with L/SC-CO 2 , with monomer and with initiator, to which one or more of the abovementioned additives are optionally added.
  • the respective amounts of C0 2 and monomer introduced into the reactor are such that the weight ratio of the C0 2 to the monomer is generally between 0.5/1 and 100/1, preferably between 0.6/1 and 30/1. The best results are obtained when the [C0 2 /monomer] weight ratio is between 0.6/1 and 5/1, very particularly between 0.8/1 and 3/1.
  • the order in which the L/SC-C0 2 , the monomer and the initiator are introduced into the reactor is not particularly critical.
  • the monomer drawn off from a storage container then compressed and heated to the pressure and to the temperature at which the polymerization step is carried out, is mixed with the L/SC-C0 2 , before addition of the initiator to the mixture thus formed.
  • a predominant proportion, or even almost all, of the L/SC-C0 2 circulates in a closed loop in the device in which the process according to the invention is carried out and is therefore recycled to the reactor as a mixture with the monomer not converted to polymer (that is to say not polymerized in the reactor).
  • the first source comprises the fresh monomer, drawn off from the storage container then compressed, as mentioned above ;
  • the second source comprises the monomer, not converted to polymer, which is recycled.
  • This second source for feeding the reactor with monomer may itself comprise several streams, preferably two streams.
  • the process according to the invention comprises the recompression (4) of the mixture of monomer not converted to polymer and of C0 2 (second stream). This recompression may advantageously be carried out in several steps, preferably in two steps such as
  • the feeding of the reactor with a recompressed and recycled mixture, in the liquid, gaseous or supercritical state, of monomer not converted to polymer and of C0 2 (second stream), may be carried out at a plurality of points.
  • a portion of the feeding of the reactor with recycled mixture is carried out in a delayed manner, by injecting said mixture at several different points, following one another along the entire length of the reactor, downstream of the fresh monomer feed point, this makes it possible to contribute advantageously to the control of the temperature of the polymerization and thus to reduce the amount of heat-transfer fluid necessary for this control.
  • initiators will preferably be chosen that have a relatively short half-life so that no residues of active initiator remain on leaving the reactor.
  • the organic radical initiator is thus preferably also introduced into the reactor at a plurality of points.
  • the number of points through which the reactor may optionally be fed with the mixture of monomer not converted to polymer and of C0 2 and, possibly, with the initiator, is not critical and depends on the geometry of the reactor.
  • the reactor is advantageously fed with the second stream, and preferably also with initiator, at a number of points between 2 and 20, preferably between 3 and 10 and particularly preferably between 4 and 8.
  • the suspension resulting from the reactor which is generally in the form of polymer particles dispersed in the liquid, gaseous or supercritical mixture of C0 2 and of monomer not converted to polymer (dispersing phase), is subjected to an expansion (1) and to a
  • the expansion (1) to which the suspension resulting from the reactor is subjected and the separation (2) of the expanded suspension resulting from the reactor into first and second streams may advantageously be carried out in several steps at successively decreasing pressures.
  • the expansion (1) and the separation (2) may be carried out in two steps (as regards the expansion (1), these two steps are also referred to as “first expansion” and “second expansion” in the present description).
  • the suspension resulting from the reactor may then firstly be advantageously brought, via a first expansion, back to a pressure intermediate between that existing in the reactor and atmospheric pressure.
  • This intermediate pressure must be low enough so that the density of the liquid, gaseous or supercritical mixture of C0 2 and of monomer not converted to polymer decreases substantially, by simple decompression in the supercritical state, or by vaporization.
  • substantially reduction in the density of the liquid, gaseous or supercritical mixture of C0 2 and of monomer not converted to polymer is understood, in the present description, to mean a reduction in this density advantageously by at least a factor of 3, preferably by at least a factor of 5.
  • This intermediate pressure is advantageously below the critical pressure, preferably between 2 and 20 times lower, more particularly between 5 and 16 times lower and, very particularly preferably, between 7 and 13 times lower than that existing in the reactor.
  • This first expansion of the suspension resulting from the reactor may be carried out in any known device, such as, for example, an automatic valve.
  • the second expansion of the suspension resulting from the reactor may preferably be carried out on the, optionally reheated, solid phase of this suspension, in order to bring it from the intermediate pressure, achieved after the first expansion, to atmospheric pressure.
  • the separation (2) of the halogenated polymer contained in the solid phase of the expanded suspension resulting from the reactor (first stream) may be carried out by any known means for separating a solid and a gas.
  • filtration means preferably bag filters, are used to carry out this separation. It is preferred to carry out an at least partial separation of the solid phase of the suspension after each expansion, with concomitant discharge, for recycling to the reactor, of the dispersing phase comprising the C0 2 and the monomer not converted to polymer.
  • said suspension is, for this purpose, reheated, with recovery of the cold energy generated by the expansion, which prevents the partial condensation of the mixture of C0 2 with the unconverted monomer, which constitutes the dispersing phase of the suspension.
  • This reheating advantageously simplifies the subsequent separation of the dispersed solid phase of the suspension, essentially constituted of the synthesized polymer.
  • the reheating (3) is applied to the expanded suspension, advantageously before or after its separation into first and second streams, and is combined with the recovery of the cold energy generated by the expansion.
  • the reheating (3) which is combined with the recovery of the cold energy, may be applied to the first stream resulting from the separation of the expanded suspension, containing the solid phase that comprises the halogenated polymer. It may also be applied after each constituent step of the expansion (1).
  • the reheating, which is combined with the recovery of the cold energy is carried out after the first expansion of the suspension resulting from the reactor.
  • This reheating may take place in any suitable device that enables it to be carried out during an operation that simultaneously involves the cooling of the mixture, recycled to the reactor, of C0 2 and of monomer not converted to polymer.
  • This cooling is advantageously carried out by virtue of the recovery, preferably simultaneous recovery, of the cold energy generated during the expansion of the suspension resulting from the reactor.
  • the device suitable for the reheating is preferably a cross-flow heat exchanger providing heat exchange between, on the one hand, the expanded suspension resulting from the reactor which travels through it in one direction and, on the other hand, the mixture of C0 2 and of monomer not converted to polymer which travels through it in the other direction.
  • this process is characterized in that the expansion (1) of the suspension resulting from the reactor is carried out in several steps and in that the reheating (3) and the recovery of the cold energy which is combined therewith are carried out after the first expansion.
  • the reheating (3) and the recovery of the cold energy generated by the expansion are preferably simultaneous.
  • the solid halogenated polymer obtained according to the process of the invention is generally collected in the form of submicron-sized particles.
  • additives may optionally be added thereto.
  • plasticizers such as adipates and organophosphates for example ;
  • fillers such as calcium carbonate, talc and dolomite for example ;
  • lubricants such as organic waxes, fatty acids and alcohols, esters or metal salts for example ;
  • flame retardants such as metal oxides for example.
  • the solid halogenated polymer obtained is generally degassed by conventional means in order to remove the residual traces of unconverted monomer.
  • the solid halogenated polymer obtained contains, depending on the effectiveness and number of expansions of the suspension resulting from the reactor, between 0.2 and 5 % by weight, preferably between 0.5 and 3 % by weight of unconverted monomer.
  • the conventional means for removing residual traces of unconverted monomer also referred to as "degassing" in the present description
  • to degas and “degassing” are used to define the passage of the unconverted monomer, present in dissolved, absorbed, adsorbed or occluded form in the solid halogenated polymer, to the gaseous state.
  • the preparation of the halogenated polymer and its degassing and its forming into granules in order to obtain a ready-to-use polymer.
  • the forming of the halogenated polymer into granules is generally carried out in an extruder.
  • extruder is understood to mean any continuous device comprising at least one feed zone and, at its outlet, a discharge zone preceded by a compression zone, the latter forcing the molten mass to pass through the discharge zone.
  • the discharge zone is advantageously followed by a granulating device that gives the extruded polymer its final form.
  • twin screws which, in the latter case, may cooperate in a co-rotating or counter-rotating manner (same direction of rotation or opposite directions of rotation).
  • Counter-rotating twin-screw extruders are preferred because they prevent the excessive shear forces which could lead to degradation of the polymer.
  • the extruder that can be used for carrying out the process of the invention according to this variant is arranged so that it advantageously comprises at least one feed zone, one melting or gelling zone, at least one degassing zone, optionally one zone for introducing additives, and one discharge zone.
  • the order in which the zones between the feed and the discharge are sequenced may be different from the order in which they are mentioned above. Each of these zones has a very specific function and is at a very specific temperature.
  • the extruder preferably comprises at least one degassing zone that itself advantageously comprises at least one degassing vent. At least one degassing vent
  • the extruder advantageously communicates with a means for creating the vacuum, such as for example a vacuum pump, in order to remove the residual unconverted monomer contained in the halogenated polymer.
  • a means for creating the vacuum such as for example a vacuum pump
  • the extruder comprises at least two degassing zones, the first of which is maintained at a pressure close to atmospheric pressure, and the second of which operates at reduced pressure.
  • the second liquid, gaseous or supercritical stream which is a mixture of C0 2 and of monomer not converted to polymer, resulting from the
  • step (4) separation (2) of the expanded suspension resulting from the reactor, is (step (4) ) recompressed, optionally cooled, then recycled to the feed of the reactor where the polymerization step of the process according to the invention takes place.
  • the monomer not converted to polymer, resulting from the degassing of the halogenated polymer may also be recompressed, cooled, then recycled to the reactor.
  • it may advantageously be recycled separately to the reactor or, preferably, be combined with the second stream in order to produce a supplementary mixture of monomer not converted to polymer and of C0 2 .
  • the degassing technique releases the monomer at several different sources, (such as for example in an extruder with several degassing zones), it is up to those skilled in the art to determine the practical advantage of recycling each source of monomer.
  • the recompression (4) of the mixture of C0 2 and of monomer not converted to polymer (second stream) may be carried out in several steps.
  • the recompression (4) is carried out at a pressure and at a temperature which are suitable for ensuring the condensation thereof into the liquid phase.
  • the pressure applied to the mixture during its recompression during this step is, for example, between atmospheric pressure and 10 MPa, preferably between atmospheric pressure and 5 MPa.
  • the cooling of the mixture of C0 2 and of monomer not converted to polymer (second stream) is optional insofar as the recompression (4) may be carried out under isothermal conditions (for example in a liquid ring pump) or under conditions that involve a release of heat energy (resulting from the conversion of the work carried out for example by a conventional compressor).
  • isothermal conditions for example in a liquid ring pump
  • heat energy resulting from the conversion of the work carried out for example by a conventional compressor
  • This cooling may be carried out in any suitable device, such as one or more condensers and/or one or more heat exchangers, but it is preferred to carry it out, at least in part, simultaneously with the reheating of the expanded suspension resulting from the reactor, by virtue of the recovery of the cold energy generated during the expansion of said suspension.
  • the device suitable for the cooling of the second stream is the cross-flow heat exchanger, the function of which was explained above.
  • the mixture of C0 2 and of monomer not converted to polymer, and also, optionally, the monomer not converted to polymer resulting from the degassing operation, which are advantageously compressed in the supercritical step, or compressed and recondensed in liquid phase, are then recycled to the reactor feed as described above.
  • This recycling may advantageously comprise one or more purification steps. These may be based on any technique known to those skilled in the art, including partial condensation, settling, adsorption and the combined use thereof.
  • the invention also relates to a device, comprising at least one pressurized reactor for the polymerization of at least one halogenated monomer in a medium comprising carbon dioxide in the liquid (L-C0 2 ) or supercritical (SC-C0 2 ) state.
  • This device can especially be used for the implementation of the process for the continuous preparation of a
  • This device comprises at least, besides the pressurized reactor :
  • these means for reheating the expanded suspension resulting from the reactor and the means for recovering the cold energy generated by the expansion of the suspension are advantageously combined in the form of a cross-flow heat exchanger providing heat exchange between, on the one hand, the expanded suspension, which travels through it in one direction and, on the other hand, the mixture of C0 2 and of monomer not converted to polymer which travels through it in the other direction ;
  • the second stream which is a mixture of C0 2 and of monomer not converted to polymer, and, optionally, the monomer resulting from the degassing of the polymer, completely or partially ;
  • means for degassing the halogenated polymer optionally in combination with continuous means of forming the polymer into granules ; preferably these means take the form of a counter-rotating twin-screw extruder ; particularly preferably, the extruder comprises at least one degassing zone that itself comprises at least one degassing vent that communicates with a means for creating the vacuum, such as for example a vacuum pump, in order to remove the residual unconverted monomer contained in the halogenated polymer.
  • a means for creating the vacuum such as for example a vacuum pump
  • the continuous preparation process and the device according to the invention advantageously make it possible to obtain, more economically than via conventional polymerization processes in an aqueous medium, halogenated polymers that are dry, ready-to-use and of high purity, considering the absence of compounds which are generally present in the conventional aqueous
  • a tubular reactor C made of carbon steel comprises (not shown in detail or to scale) 6 sections with a length of 300 m constituted of straight segments joined together by 180° bends and jacketed by a jacket, itself also made of several sections, in which a coolant circulates.
  • This reactor is fed, via the monomer pump B which brings it to a pressure of 15 MPa and at a temperature of 50°C, with fresh vinyl chloride (monomer) from the fresh (liquid) monomer storage tank A and with liquid vinyl chloride recycled via the line R 3 .
  • This reactor is also fed with a recycled mixture of vinyl chloride in SC-CO 2 , for 20 % of the volume of this mixture via the line R 2 and, for the remaining 80 % of the volume, via the 5 injectors shown schematically as Ri, respectively.
  • the segments of the reactor and of their jacketing have a diameter that increases between the inlet and outlet of the reactor.
  • a solution of a heavy organic peroxide in an aliphatic monoalcohol is also introduced into the reactor (supply not shown) as an initiator, by injecting into the reactor at the same points as the mixture of monomer and of C0 2 recycled via the line R 2 and the injectors Ri .
  • the suspension which leaves the reactor firstly undergoes an adiabatic expansion to 1.4 MPa by passing through the automatic expansion valve E.
  • the latter is reheated in the cross-flow heat exchanger O, which is travelled through in the other direction by the vaporized mixture V 4 of monomer not converted to polymer and of C0 2 .
  • the solid portion of the suspension thus expanded and reheated, constituted essentially of the synthesized polymer, is then separated in the bag filter Fi, the vaporized portion, comprising the monomer not converted to polymer and the C0 2 , being discharged as Vi in order to be recycled.
  • the solid portion of the suspension separated in the bag filter Fj is subjected to a second expansion to 0.1 MPa via the (upstream-downstream) flood gate or lock chamber G and again separated, in the bag filter F 2 , from the vapour phase generated which is discharged as V 2 in order to be recycled.
  • the solid polymer (Pol) collected in the form of submicron-sized particles, optionally to which stabilizers and conventional additives (Add) have been added, is introduced, via the hopper H, into a counter-rotating twin-screw extruder I.
  • the residual unconverted monomer contained in the polymer powder (around 1 % by weight) is removed in a first vent at atmospheric pressure and 180°C, then under vacuum at around 133 Pa (absolute) and at a temperature of 180°C in a second vent. The vacuum is created by the vacuum pump . Finally, ready-to-use granules (GR) of vinyl chloride polymer are obtained.
  • V 3 vapour phase
  • V 3 The monomer not converted to polymer, discharged as V 3 (vapour phase) and the mixture of unconverted monomer and of C0 2 , discharged as Vi (vapour phase) and V 2 (vapour phase) are recompressed to 2.5 MPa via the multi-stage compressors Li and L 2 with cooling via the heat exchanger M.
  • the vapour/liquid separator or decanter N the separation between a liquid phase and a vapour phase comprising the vaporized mixture of unconverted monomer and of C0 2 is carried out.
  • the liquid phase comprises a two-phase liquid mixture, of which the upper organic liquid phase (c o rg ), constituted essentially of monomer, is recycled as R 3 to the pump B and of which the lower aqueous phase ((p aq ) (resulting from impurities contained in the additives and initiator solutions) is discharged from the device.
  • the vapour phase comprising the mixture of unconverted monomer and of C0 2 , recycled as V 4 , with optional fresh C0 2 make-up via the tank A 2 , is condensed via the cross- flow heat exchanger O by heat exchange with the suspension resulting from the reactor C that travels through the heat exchanger in the other direction after its adiabatic expansion by passing through the automatic expansion valve E (see above).
  • the condensed mixture of unconverted monomer and of C0 2 is then purged of inert gases at P (vapour/liquid separator) and recycled to the reactor as Ri and R 2 by means of the pump Q, as mentioned above.

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

Abstract

L'invention concerne un procédé continu de préparation d'un polymère halogéné ainsi qu'un dispositif de mise en oeuvre associé. Le procédé selon l'invention comprend une étape de polymérisation d'au moins un monomère halogéné dans un milieu contenant du dioxyde de carbone à l'état liquide ou supercritique (L/SC-CO2), dans au moins un réacteur sous pression. Le procédé selon l'invention comprend au moins : - (1) une étape de dilatation de la suspension provenant du réacteur ; - (2) une étape de séparation de la suspension dilatée provenant du réacteur en un premier flux constitué par la phase solide contenant le polymère halogéné, et en un deuxième flux liquide, gazeux ou supercritique qui est un mélange de CO2 et de monomère non converti en polymère ; et de récupération de ces premier et deuxième flux ; - (3) une étape de réchauffage facultatif appliqué sur la suspension dilatée, avant ou après sa séparation en premier et deuxième flux, combinée à une récupération de l'énergie froide générée par la dilatation ; - (4) une étape de recompression du deuxième flux et de refroidissement facultatif de celui-ci, afin de recycler le flux vers la charge de réacteur, avec une composition de monomère frais et, éventuellement, une composition de CO2 ; et - (5) une étape finale de dégazage du polymère halogéné, facultativement associée à une technique continue de conformation du polymère en granulés. L'invention concerne également un dispositif permettant la mise en oeuvre de ce procédé.
PCT/EP2010/069491 2009-12-16 2010-12-13 Procédé de préparation de polymère halogéné et dispositif de mise en oeuvre associé WO2011073132A1 (fr)

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FR0959027 2009-12-16
FR0959027A FR2953844B1 (fr) 2009-12-16 2009-12-16 Procede de preparation d'un polymere halogene et dispositif pour sa mise en oeuvre

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Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998028351A1 (fr) * 1996-12-23 1998-07-02 E.I. Du Pont De Nemours And Company Polymerisation de fluoromonomeres dans du co¿2?
WO2001034667A1 (fr) * 1999-11-12 2001-05-17 North Carolina State University Procede continu de fabrication de polymeres dans du dioxyde de carbone
US6258910B1 (en) 1999-06-09 2001-07-10 Occidental Chemical Corporation Polymerizing vinyl chloride in carbon dioxide
WO2002055567A2 (fr) * 2001-01-10 2002-07-18 Solvay (Société Anonyme) Procede de preparation de polymeres halogenes en deux etapes et polymeres halogenes plurimodales

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
WO1998028351A1 (fr) * 1996-12-23 1998-07-02 E.I. Du Pont De Nemours And Company Polymerisation de fluoromonomeres dans du co¿2?
US6258910B1 (en) 1999-06-09 2001-07-10 Occidental Chemical Corporation Polymerizing vinyl chloride in carbon dioxide
WO2001034667A1 (fr) * 1999-11-12 2001-05-17 North Carolina State University Procede continu de fabrication de polymeres dans du dioxyde de carbone
WO2002055567A2 (fr) * 2001-01-10 2002-07-18 Solvay (Société Anonyme) Procede de preparation de polymeres halogenes en deux etapes et polymeres halogenes plurimodales

Non-Patent Citations (1)

* Cited by examiner, † Cited by third party
Title
GE LI ET AL.: "Polymerization of vinyl chloride in supercritical carbon dioxide", POLYMER PREPRINTS, vol. 42, no. 2, 2001, pages 817

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FR2953844B1 (fr) 2012-02-24
FR2953844A1 (fr) 2011-06-17

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