EP0977783A1 - Method for producing homopolymerizates and copolymerizates - Google Patents

Method for producing homopolymerizates and copolymerizates

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Publication number
EP0977783A1
EP0977783A1 EP98925480A EP98925480A EP0977783A1 EP 0977783 A1 EP0977783 A1 EP 0977783A1 EP 98925480 A EP98925480 A EP 98925480A EP 98925480 A EP98925480 A EP 98925480A EP 0977783 A1 EP0977783 A1 EP 0977783A1
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EP
European Patent Office
Prior art keywords
microsuspension
polymerization
reactor
monomers
monomer
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.)
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Application number
EP98925480A
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German (de)
French (fr)
Inventor
Graham Edmund Mckee
Sven Lawrenz
Klemens Mathauer
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BASF SE
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BASF SE
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Publication date
Application filed by BASF SE filed Critical BASF SE
Publication of EP0977783A1 publication Critical patent/EP0977783A1/en
Withdrawn legal-status Critical Current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
    • C08F2/00—Processes of polymerisation
    • C08F2/12—Polymerisation in non-solvents
    • C08F2/16—Aqueous medium
    • 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
    • C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
    • C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof
    • C08F20/42—Nitriles
    • C08F20/44—Acrylonitrile
    • 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
    • C08F12/00—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 an aromatic carbocyclic ring
    • C08F12/02—Monomers containing only one unsaturated aliphatic radical
    • C08F12/04—Monomers containing only one unsaturated aliphatic radical containing one ring
    • C08F12/06—Hydrocarbons
    • C08F12/08—Styrene
    • 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
    • C08F2/12—Polymerisation in non-solvents
    • C08F2/16—Aqueous medium
    • C08F2/18—Suspension polymerisation
    • 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
    • C08F20/00—Homopolymers and copolymers of compounds having one or more unsaturated aliphatic radicals, each having only one carbon-to-carbon double bond, and only one being terminated by only one carboxyl radical or a salt, anhydride, ester, amide, imide or nitrile thereof
    • C08F20/02—Monocarboxylic acids having less than ten carbon atoms, Derivatives thereof
    • C08F20/10—Esters
    • C08F20/12—Esters of monohydric alcohols or phenols
    • 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
    • C08F291/00—Macromolecular compounds obtained by polymerising monomers on to macromolecular compounds according to more than one of the groups C08F251/00 - C08F289/00

Definitions

  • the present invention relates to a process for the continuous production of particulate homopolymers and copolymers using the technique of microsuspension polymerization.
  • Polymerization in a disperse system such as an emulsion or a suspension is a technically proven process for the production of particulate polymers.
  • Important products of such processes are polyvinyl acetate, polyvinyl chloride and polytetrafluoroethylene.
  • the use of particularly finely dispersed monomers is sought in the industrial manufacturing process. Therefore, methods such as the miniemulsion or microsuspension process, both of which allow the intermediate production and polymerization of such particularly finely dispersed monomers, are becoming increasingly important.
  • the mixture of one or more monomers and a stabilizing suspending aid - protective colloids or surfactant emulsifiers are usually used - is subjected to very high shear forces in water, which leads to the formation of a very high shear force fine emulsion of droplets with a diameter of about 0.1-2 ⁇ m leads.
  • microsuspension This emulsion, hereinafter referred to as microsuspension, is then mixed with a hydrophobic radical polymerization initiator in a second step and, after heating to the required reaction temperature, polymerized to particles of a diameter of approximately 0.1-50 ⁇ m (see, for example, . 'Handbuch der Technischen Polymerchemie', VCH Verlagsgesellschaft mbH, Weinheim, 1993, p. 450).
  • emulsion, suspension and terms derived therefrom such as mini-emulsion, microsuspension, emulsify, suspend and others are used differently in the literature in connection with polymerizations. This can lead to unclear descriptions.
  • emulsion, suspension and microsuspension polymerization see 'Handbuch der Technischen Polymer-Chemie', VCH Verlagsgesellschaft mbH, Weinheim, 1993, p. 316 and p. 450.
  • microsuspension is understood to mean the finished, finely divided mixture of the substances to be polymerized.
  • Emulsifying means to convert the mixture of the substances to be polymerized into a microsuspension.
  • EP-B 0 443 609 discloses a microsuspension process in which various monomers are emulsified in water using a high-speed stirrer which generates very high shear forces. The total amount of the microsuspension is then converted into the polymer with a particle size of 5-50 ⁇ m diameter in a stirred tank in a batchwise process.
  • DE-A 196 33 626 which is older and has not been published in advance, proposes the polymerization of a microsuspension of, inter alia, (meth) acrylic acid derivatives and of further (meth) acrylic acid and styrene derivatives which can optionally be used as comonomers.
  • a microsuspension of, inter alia, (meth) acrylic acid derivatives and of further (meth) acrylic acid and styrene derivatives which can optionally be used as comonomers.
  • only part of the microsuspension containing monomer is placed in the stirred tank reactor and the rest is metered in continuously as the reaction proceeds.
  • the continuous polymerization in mini-emulsions here means a continuously stirred tank reactor to which a mini-emulsion generated in a tubular pre-reactor is metered in continuously.
  • the object of the present invention is to provide an industrially feasible method for the polymerization of microsuspensions. different monomers in a continuously operated tubular reactor while avoiding the disadvantages of the prior art.
  • the solution to the problem is based on the known processes for the production of particulate homopolymers or copolymers of at least one polymerizable monomer using the technique of microsuspension polymerization at a temperature of at least 0 ° C. in the presence of at least one hydrophobic radical polymerization initiator.
  • the invention is based on the known processes for the production of particulate homopolymers or copolymers of at least one polymerizable monomer using the technique of microsuspension polymerization at a temperature of at least 0 ° C. in the presence of at least one hydrophobic radical polymerization initiator.
  • the process is then characterized in that the microsuspension is produced continuously or batchwise, the polymerization takes place in at least 50% of the conversion in a tubular reactor, the process products have an average particle diameter d 50 of less than 50 ⁇ m and the tubular reactor consists of one Pipe or hose with a ratio of length to diameter (L / D) of at least 20.
  • Suitable monomers for this are, for example, (meth) acrylic acid, (meth) acrylamide, (meth) acrylonitrile, alkyl (meth) acrylates, butadiene, isoprene, alkylene oxides, styrene, substituted styrenes, vinyl acetate and vinyl chloride.
  • Alkyl (meth) acrylates are esters of (meth) acrylic acid with linear Ci- C 32 - or branched C 3 -C understand 32 alkyl radicals, in particular methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl or 2-ethylhexyl .
  • alkyl radicals can be unsubstituted or substituted by functional groups, for example by hydroxyl, amino, ether, epoxy, sulfonic acid groups or by chlorine.
  • Preferred monomers having such functional groups in the alkyl group are 2-hydroxyethyl acrylate, 2-hydroxyethyl, 3-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, Ethyldiglykolacrylat, tert-butylaminoethyl methacrylate, diethylaminoethyl acrylate, n-Butoxymethylaminomethacrylat, glycidyl methacrylate, 2-acrylamido-2-methyl - Propanesulfonic acid and 3-chloro-2-hydroxypropyl acrylate.
  • monomers with polar, acidic or basic groups makes the polymers suitable
  • the microsuspension of only one monomer is used in the polymerization step, homopolymers are formed.
  • the microsuspension of a further monomer or a monomer mixture can be fed into the tubular reactor, so that this Monomers or these monomers are partially polymerized or polymerized in shell form on the polymer particles formed first. This process can also be repeated several times with other monomers or mixtures of different compositions in order to obtain particles with several shells.
  • Additional monomers can also be metered in without prior preparation of a microsuspension by metering in the monomers or monomer mixture, water, suspending agent and, if appropriate, other additives directly. It is also possible to first transfer the previously formed polymer to another tubular reactor and then to start metering in at least one further monomer.
  • Suitable comonomers are bi- and polyfunctional monomers, for example butadiene, isoprene, divinyl esters of dicarboxylic acids such as succinic and adipic acid, diallyl and divinyl ethers, and bis-acrylic and bis-methacrylic acid esters of bifunctional alcohols such as ethylene glycol and butane-1,4-diol, 1,4-divinylbenzene and triallyecyanurate.
  • the acrylic and methacrylic acid esters of allyl alcohol and the acrylic acid esters of tricyclodecenyl alcohol (dihydrodicyclopentadienyl acrylate) are particularly suitable.
  • the tubular reactor can also be operated in the form of a circulation reactor, the microsuspension in the tubular reactor being circulated and polymerized. Part of the already polymerized microsuspension is continuously removed from the circuit and an equivalent part of new microsuspension is metered in.
  • the ratio between the amount of microsuspension that passes through a pipe cross-section in a certain time interval and the amount of microsuspension that is metered into the cycle reactor in the same time interval is generally greater than 5, preferably greater than 10 and particularly preferably greater than 20.
  • tubular reactor is understood to mean both a circulation reactor and a non-circulation-operated reactor.
  • the tubular reactor can be filled with elements which ensure better radial mixing.
  • Raschig rings, baffles or other internals and static mixers are suitable as elements.
  • a better radial mixing can also be achieved by a so-called pulsing mode of operation of the reactor.
  • This usually means a pulsating feeding of the microsuspension into the tubular reactor.
  • a pulsating driving style with a feed rate of once in 30 seconds to ten times in one second is preferred, in particular from once in 2 seconds to five times in one second.
  • the average residence time of the microsuspension in the tubular reactor depends, inter alia, on the monomers to be polymerized and is usually between 10 minutes and 10 hours, preferably between 10 minutes and 4 hours.
  • the dimensions of the tubular reactor depend on the desired properties of the particulate polymers to be produced.
  • the choice of the suitable reactor dimension depends, inter alia, on the polymerization rate of the monomers, on the shape of the tube and on the mode of operation of the reactor. In a cycle mode of operation, the ratio L / D is generally between 50 and 1000 and is therefore to be chosen smaller than in a non-cycle mode of operation.
  • the choice of the reactor material depends on the type of monomers to be polymerized.
  • Non-metallic materials for example polytetrafluoroethylene, and metallic, for example steels according to DIN 17440, which can be coated on the inside, for example with enamel or polymers, in particular with fluorine-containing polymers, are preferred.
  • the tubular reactor can be tempered by immersing it in a heat-transfer medium or preferably having a double jacket filled with a heat-transfer medium.
  • suitable media are, for example, water, brine, oils and other liquids.
  • the temperature selected for the polymerization in the tubular reactor essentially depends on the type of monomers and polymerization initiators used and is generally between 0 and 140 ° C., preferably between 20 and 130 ° C.
  • the tubular reactor can also be operated with a temperature program.
  • the Polymerization started at a temperature of 70 ° C and ended at 100 ° C.
  • the polymerization takes place at least 60%, in particular at least 80%, in the tubular reactor.
  • the part of the monomers which have not yet reacted completely or completely polymerize out after leaving the tubular reactor provided the suspension is still at a temperature which is sufficient for the polymerization.
  • the polymers can, if desired, be easily separated from the unreacted monomers and, if appropriate, from the other constituents of the suspension, for example by spray drying or by coagulation and drying.
  • the polymers produced by the process according to the invention have an average particle diameter d 50 , which is preferably between 0.03 and 50 ⁇ m, in particular between 0.1 and 30 ⁇ m.
  • the mean particle diameter can be determined by taking light or electron microscopic images and then measuring and counting the particles. Another method is Fraunhofer laser diffraction.
  • Suitable suspending aids are those water-soluble compounds which are able to coat the fine monomer droplets and the polymer particles formed therefrom and in this way to protect them from undesired coagulation.
  • These include, for example, cellulose derivatives, such as carboxyl and hydroxymethyl cellulose, poly-N-vinylpy ⁇ olidin, polyvinyl alcohol and polyethylene oxide, anionic polymers such as polyacrylic acid and their copolymers and cationic polymers such as poly-N-vinylimidazole in concentrations of preferably 0.02 to 5 % By weight, based on the total mass of the microsuspension.
  • Emulsifiers such as the alkali salts of aryl and alkyl sulfonic acids and of aryl and alkyl carboxylic acids, for example sodium stearate, potassium stearate, sodium oleate and potassium oleate, and also ethoxylated or propoxylated alcohols and phenols. These emulsifiers are also used in concentrations of preferably 0.02 to 5% by weight, based on the total mass of the microsuspension.
  • polyvinyl alcohols with a degree of hydrolysis of less than 96 mol%, preferably between 60 and 94 mol%, in particular between 65 and 92 mol%.
  • the preferred polyvinyl alcohols have a viscosity of 1 to 100 mPa / s, in particular 2 to 60 mPa / s, measured as a 4% strength by weight solution in water at 20 ° C. according to DIN 53015.
  • colloidal silica in concentrations of 0.2 to 5% by weight, based on the total amount of the microsuspension.
  • the microsuspension is added or at least one further monomer Addition of at least one further monomer.
  • This step can be repeated several times in order to obtain polymers with a multi-layer structure.
  • copolymers can also be prepared in such a way that after the polymerization of a monomer or monomer mixture, the polymer thus prepared is transferred to a second crude reactor, and then at least one further monomer is metered in.
  • stirred tank reactor is used instead of one second tube reactor possible, as well as the reverse procedure, that is, first of all, preparation of a polymer in a stirred tank reactor and then metering in of at least one further monomer in a tube reactor.
  • the transition from the core to the shell or the transition from one shell to the next shell is sharper the more completely a monomer is already polymerized before the metering in of at least one further monomer as such or in the form of a microsuspension is started.
  • the particle morphology can also be influenced by appropriate selection of the monomers and the reactor conditions. For example, newly fed monomers can not only polymerize shell-like onto the already polymerized particles of a previously used other monomer type, but also polymerize into these particles to a considerable extent, so that the core-shell structure is less pronounced.
  • crosslinking monomers are polymerized to form a core or a shell, then reaction, i.e. polymerizable C-C double bonds remain, onto which a further monomer can be grafted in the next polymerization step.
  • reaction i.e. polymerizable C-C double bonds remain, onto which a further monomer can be grafted in the next polymerization step.
  • Such grafting reactions are known to the person skilled in the art.
  • radical polymerization initiators Compounds which form free radicals are suitable as radical polymerization initiators, provided they are oil-soluble. These include peroxides, azo compounds and compounds with labile CC bonds. If such monomers are to be polymerized that spontaneously tend to polymerize at elevated temperature, the addition of a radical polymer sationsinitiators be waived. This group of monomers includes in particular styrene and its derivatives.
  • peroxides those with a ratio of carbon to oxygen of greater than 3 to 1, such as dilauryl peroxide, dibenzoyl peroxide, diacetyl peroxidicarbonate, dimyristil peroxidicarbonate and bis- (3,5,5-trimethylhexanoyl) peroxide, in particular dilauryl peroxide, are preferred.
  • azo compounds 2,2'-azobis (isobutyronitrile) and 2,2'-azobis (2-methylbutyronitrile) are preferred.
  • 3,4-dimethyl-3,4-dipherrylhexane and 2,3-dimethyl-2,3-diphenylbutane are preferably used.
  • polymerization initiators are used in an amount of 0.05 to 4% by weight, based on the amount of the monomer, preferably 0.1 to 2% by weight, in particular 0.3 to 1.0% by weight. Of course, this quantity does not apply if the monomer is also the initiator. Mixtures of the polymerization initiators mentioned can also be used.
  • the polymerization initiator can be added as such, but preferably as a solution, emulsion or suspension, either to the mixture to be emulsified to form a microsuspension, to the already prepared microsuspension or to the microsuspension to be polymerized in the crude reactor.
  • Organic solvents such as benzene, toluene, xylene, ethylbenzene, cyclohexane and the monomers themselves are suitable as the solvent or as the liquid phase for the polymerization initiator.
  • the mixture to be emulsified or the already prepared microsuspension can be more than 0.1% by weight, preferably more than 1% by weight, in particular more than 5% by weight, of at least one solid in dissolved, swollen or suspended form are added.
  • These solids can be polymers, coloring and ferromagnetic pigments as well as other substances such as minerals.
  • carbon black black particulate polymers are produced, which are used in particular as copier toners.
  • the use of ferromagnetic pigments leads to the formation of particulate polymers with ferromagnetic properties.
  • Such polymers are particularly suitable for the production of magnetic tapes and magnetic foils.
  • additives which influence the product properties can also be added in the process according to the invention, depending on the desired properties of the polymers.
  • - molecular weight regulators for example t-dodecyl mercaptan or 2-
  • Buffers to regulate the pH value for example citrate buffers, disodium hydrogen phosphate and sodium dihydrogen phosphate, inhibitors which simultaneously inhibit the process of microsuspension polymerization which is an undesirable competitive reaction
  • Emulsion polymerization in which essentially undesirable smaller polymers are formed, is suppressed, for example chromium (VI) salts, in particular potassium and sodium dichromate.
  • VI chromium
  • microsuspension used in the process according to the invention is made up of monomer, suspending agent, water and, if appropriate, the others Solid and other additives specified above and optionally polymerization initiator prepared by allowing very high shear forces to act on the mixture of these substances. Methods for being able to exert very high shear forces are known to the person skilled in the art.
  • stirrers and homogenizers examples are: Laboratory dissolver Dispermat, VMA-Getzmann, Reichshof, DE
  • the microsuspension is usually produced at room temperature, but can also be carried out at a lower or higher temperature, depending on the type of monomers and other substances.
  • the stirrers are usually operated at speeds between 1000 and 25000 revolutions per minute (rpm), preferably between 2000 and 15000 rpm, with a stirring time which can be between 0.1 seconds and several hours.
  • the amount of water in which the monomers and the suspending aids are dispersed is usually from 15 to 95% by weight, preferably from 35 to 85% by weight, and particularly preferably from 40 to 75% by weight, based in each case on the total Monomers, water and suspending agents.
  • the microsuspension is produced either batchwise or continuously.
  • the mixture of the substances to be emulsified is processed in a container with one of the stirrers or homogenizers mentioned above to form the microsuspension.
  • the homogenizer can also be arranged parallel to the container and the mixture is then circulated through the homogenizer.
  • the substances to be emulsified are fed continuously to the homogenizer, and the microsuspension formed is then also fed continuously to the tubular reactor.
  • the continuous preparation of the microsuspension can also be carried out in such a way that only a part of the microsuspension is fed to the tubular reactor and the rest passes through the homogenizer again.
  • This circular mode of operation is particularly recommended if the absolute droplet size or the size distribution of the droplets should be unsatisfactory with a single throughput through the homogenizer.
  • microsuspensions of high and uniform quality Separate the area-intensive, discontinuous production of the microsuspension from the actual polymerization and feed the microsuspension to the tube reactor as required.
  • the particulate polymers are dispersed in water and, if necessary, can be spray-dried directly or, after separation of the aqueous phase, for example by sieving, filtering, decanting or centrifuging, can be dried further in the customary manner, for example by warm air or with the help of a power dryer.
  • this polymer-containing dispersion which generally has a viscosity of 100-500 mPa / s, can also be further processed as such.
  • the method according to the invention enables a stable, i.e. Operation without blockage of the reactor. This also applies to very long operating times of the tubular reactor, which are a multiple of the average residence time of the microsuspension in the tubular reactor.
  • the microsuspension used does not tend to show signs of coagulation under the chosen reaction conditions.
  • the homopolymers and copolymers prepared according to the invention have good performance properties. They are used, for example, as additives for thermoplastic molding compositions, as constituents of copier toners, paper and leather auxiliaries, coatings for magnetic tapes and magnetic foils, and as coloring and coating components.
  • Acrylonitrile, butyl acrylate, dihydrodicyclopentadienyl acrylate and styrene are products of BASF AG, Ludwigshafen, DE and were used without further purification.
  • the Mowiol ® polyvinyl alcohols are products of Hoechst AG, Frankfurt am Main, DE.
  • the first number after the brand name indicates the viscosity of a 4 wt. -% solution of the polyvinyl alcohol in water at 20 ° C in [mPa / s], measured according to DIN 53015.
  • the second number characterizes the degree of hydrolysis of the polyvinyl alcohol in mol%.
  • the polymerization initiators are commercially available products.
  • the metering rate was 500 ml / h.
  • the temperature of the reactor contents was kept at 75 ° C. using a water bath. After an average residence time of 20 minutes in the tubular reactor, the polymerized suspension was collected.
  • the tubular reactor was operated for a total of 5 hours and 45 minutes under these conditions. The suspension showed no coagulum and the tubular reactor showed no signs of clogging.
  • the solids content was 33% by weight.
  • the average particle diameter d 50 was 2.5 ⁇ m.
  • Example 2 To prepare a copolymer, the experiment from Example 1 was repeated and the suspension containing butyl acrylate polymer thus prepared was metered into a second crude reactor which had the same dimensions and the same material composition as that in Example 1. At a temperature of 75 ° C., the two given below were given Mixtures A and B are metered in separately in a continuous manner. The metering rate was chosen so that the weight ratio of mixture B to polybutyl acrylate was 20 to 80.
  • the polymerized suspension was collected.
  • the crude reactor was operated for a total of 5 hours under these conditions.
  • the suspension showed no coagulum and the crude reactor showed no signs of constipation.
  • the average particle diameter d 50 was 2 ⁇ m.

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

Abstract

The method used to polymerize a microsuspension enables continuous production of particular homopolymerizates and copolymerizates from at least one polymerizable monomer. The polymerization of the microsuspension, to which addition agents can be added depending on the desired application, is carried out in a tubular reactor at a temperature of at least 0 °C C in the presence of a hydrophobic radical polymerization initiator, resulting in particular homopolymerizates and copolymerizates of an average diameter d50 of at least 50 νm. The polymerizates obtained by this method find applications as addition agents for thermoplastic moulding compounds, as copier toner components, as auxiliary agents for paper and leather, as coating agents for magnetic tapes and foils and as colour and paint components.

Description

Verfahren zur Herstellung von partikelförmigen Homo- und Copolymerisaten aus Mikrosuspensionen in einem Rohrreaktor Process for the production of particulate homopolymers and copolymers from microsuspensions in a tubular reactor
Die vorliegende Erfindung betrifft ein Verfahren zur kontinuierlichen Herstellung von partikelförmigen Homo- und Copolymerisaten in Technik der Mikrosuspensionspolymerisation.The present invention relates to a process for the continuous production of particulate homopolymers and copolymers using the technique of microsuspension polymerization.
Bei solchen Verfahren werden als Monomere unter anderem Derivate des Styrols und der (Meth)acrylsäure zusammen mit einem Suspendierhilfsmittel in einer mit den Monomeren nicht mischbaren Flüssigkeit, üblicherweise Wasser, sehr hohen Scherkräften ausgesetzt und die so erhaltene Mikro- suspension unter Einwirkung eines hydrophoben, d.h. öllöslichen radikalischen Polymerisationsinitiators polymerisiert.In such processes, derivatives of styrene and (meth) acrylic acid together with a suspending aid in a liquid immiscible with the monomers, usually water, are exposed as monomers, among other things, to very high shear forces and the micro suspension thus obtained under the action of a hydrophobic, i.e. polymerized oil-soluble radical polymerization initiator.
Die Polymerisation in einem dispersen System wie einer Emulsion oder einer Suspension ist ein technisch erprobtes Verfahren zur Herstellung von partikelförmigen Polymerisaten. Bedeutende Produkte solcher Verfahren sind Polyvinylacetat, Polyvinylchlorid und Polytetrafiuorethylen.Polymerization in a disperse system such as an emulsion or a suspension is a technically proven process for the production of particulate polymers. Important products of such processes are polyvinyl acetate, polyvinyl chloride and polytetrafluoroethylene.
Für die Herstellung bestimmter Produkte wird im industriellen Herstellverfahren der Einsatz von besonders fein dispergierten Monomeren angestrebt. Daher gewinnen Methoden wie das Miniemulsions- oder Mikrosuspensions- verfahren, die beide die intermediäre Erzeugung und Polymerisation solcher besonders fein dispergierter Monomerer erlauben, zunehmende Bedeutung. Beim letztgenannten Verfahren wird zunächst die Mischung eines oder mehrerer Monomeren und eines stabilisierenden Suspendierhilfsmittels - üblicherweise werden Schutzkolloide oder tensidische Emulgatoren verwendet - in Wasser sehr hohen Scherkräften ausgesetzt, was zur Bildung einer sehr feinen Emulsion von Tröpfchen mit einem Durchmesser von etwa 0, 1 - 2 μm führt. Diese Emulsion, im folgenden Mikrosuspension genannt, wird dann in einem zweiten Schritt mit einem hydrophoben radikalischen Polymerisationsinitiator versetzt und nach Aufheizen auf die erforderliche Reaktions- temperatur zu Partikeln eines Durchmessers von etwa 0,1 - 50 μm polyme- risiert, (siehe z. B. 'Handbuch der Technischen Polymerchemie', VCH Verlagsgesellschaft mbH, Weinheim, 1993, S. 450).For the manufacture of certain products, the use of particularly finely dispersed monomers is sought in the industrial manufacturing process. Therefore, methods such as the miniemulsion or microsuspension process, both of which allow the intermediate production and polymerization of such particularly finely dispersed monomers, are becoming increasingly important. In the latter process, the mixture of one or more monomers and a stabilizing suspending aid - protective colloids or surfactant emulsifiers are usually used - is subjected to very high shear forces in water, which leads to the formation of a very high shear force fine emulsion of droplets with a diameter of about 0.1-2 μm leads. This emulsion, hereinafter referred to as microsuspension, is then mixed with a hydrophobic radical polymerization initiator in a second step and, after heating to the required reaction temperature, polymerized to particles of a diameter of approximately 0.1-50 μm (see, for example, . 'Handbuch der Technischen Polymerchemie', VCH Verlagsgesellschaft mbH, Weinheim, 1993, p. 450).
Die Bezeichnungen Emulsion, Suspension und daraus abgeleitete Begriffe wie Miniemulsion, Mikrosuspension, emulgieren, suspendieren und andere werden in der Literatur im Zusammenhang mit Polymerisationen teilweise unterschiedlich benutzt. Das führt unter Umständen zu unklaren Beschreibungen. Zur Definition der hier verwendeten Begriffe Emulsions-, Suspensions- und Mikrosuspensionspolymerisation siehe 'Handbuch der Technischen Polymer- Chemie', VCH Verlagsgesellschaft mbH, Weinheim, 1993, S. 316 und S. 450.The terms emulsion, suspension and terms derived therefrom such as mini-emulsion, microsuspension, emulsify, suspend and others are used differently in the literature in connection with polymerizations. This can lead to unclear descriptions. For the definition of the terms emulsion, suspension and microsuspension polymerization used here, see 'Handbuch der Technischen Polymer-Chemie', VCH Verlagsgesellschaft mbH, Weinheim, 1993, p. 316 and p. 450.
Beim hier relevanten Verfahren handelt es sich um eine Mikrosuspensionspolymerisation. In Einklang mit den Definitionen der oben zitierten Literatur werden daher die Begriffe wie folgt verwendet:The process relevant here is a microsuspension polymerization. In accordance with the definitions of the literature cited above, the terms are therefore used as follows:
unter der Mikrosuspension ist die fertige feinverteilte Mischung der zu polymerisierenden Stoffe zu verstehen emulgieren bedeutet die Mischung der zu polymerisierenden Stoffe in eine Mikrosuspension zu überführen.The microsuspension is understood to mean the finished, finely divided mixture of the substances to be polymerized. Emulsifying means to convert the mixture of the substances to be polymerized into a microsuspension.
Als Nachteile von Rohrreaktoren - als einer von mehreren Reaktorvarianten - werden gesehenThe disadvantages of tubular reactors - as one of several reactor variants - are seen
- die geringere Flexibilität bei einem Produktwechsel die Gefahr einer Verstopfung des Reaktors und im Falle einer schlechten radialen Durchmischung eine größer werdende Verweilzeitenverteilung und damit einhergehend eine breitere Verteilung der Teilchengrößen.- less flexibility when changing products the risk of a blockage of the reactor and, in the case of poor radial mixing, an increasing residence time distribution and, as a result, a wider distribution of the particle sizes.
Insbesondere auf Grund der beiden letztgenannten Punkte sind bislang nur wenige Polymerisationen in Rohrreaktoren bekannt geworden.Due to the last two points in particular, only a few polymerizations in tubular reactors have become known.
So ist in US-A 4,713,434 die kontinuierliche Polymerisation von Emulsionen verschiedener Monomerer beschrieben, wobei die Reaktion in Rohrreaktoren verläuft, die innen mit Polyethylen oder Polypropylen beschichtet sind.The continuous polymerization of emulsions of various monomers is described in US Pat. No. 4,713,434, the reaction taking place in tubular reactors which are coated on the inside with polyethylene or polypropylene.
In zwei Artikeln von D.A. Paquet, Jr. et al. in J. American Inst. Chem. Eng. , Vol. 40, No. 1, S. 73 bis 88 und S. 88 bis 97, 1994 wird ein Überblick über einige kontinuierlich betriebene Emulsionspolymerisationen gegeben, in denen durch verschiedene Methoden versucht wird die oben genannten Nachteile zu überwinden. So wird zum Beispiel die Ausführung als Kreislaufreaktor beschrieben, bei dem das Verhältnis von neu eingespeister Monomeremulsion zur Gesamtmenge der im Kreislauf gefahrenen Emul- sion sehr klein ist. Weitere Möglichkeiten sind die sogenannte gepulste Fahrweise des Reaktors und die Verwendung von Einbauten in den Reaktor, zum Beispiel Schikanen, die für eine gesteigerte Verwirbelung und Durchmischung sorgen.In two articles by D.A. Paquet, Jr. et al. in J. American Inst. Chem. Eng. , Vol. 40, No. 1, pp. 73 to 88 and pp. 88 to 97, 1994 an overview of some continuously operated emulsion polymerizations is given, in which various methods are used to try to overcome the disadvantages mentioned above. For example, the design as a circulation reactor is described in which the ratio of newly fed monomer emulsion to the total amount of the emulsion being circulated is very small. Other options are the so-called pulsed mode of operation of the reactor and the use of internals in the reactor, for example baffles, which ensure increased turbulence and mixing.
Eine ähnliche Methode wird von J. Meuldijk et al. in Chem. Eng. Sei. , Vol. 47, No. 9-11, S. 2603 -2608, 1992 beschrieben. Dort wird zur Emulsionspolymerisation von Vinylacetat ein mit Raschigringen gepackter Rohrreaktor verwendet, der zusätzlich noch mit einem Pulsator versehen ist. In EP-B 0 443 609 wird ein Mikrosuspensionsverfahren offenbart, bei dem verschiedene Monomere in Wasser unter Anwendung eines sehr hohe Scherkräfte erzeugenden Hochgeschwindigkeitsrührers emulgiert werden. Die Gesamtmenge der Mikrosuspension wird anschließend in einem Rührkessel in diskontinuierlicher Herstellweise zum Polymerisat mit einer Teilchengröße von 5 - 50 μm Durchmesser umgesetzt.A similar method is described by J. Meuldijk et al. in Chem. Eng. Be. , Vol. 47, No. 9-11, pp. 2603-2608, 1992. There, a tube reactor packed with Raschig rings is used for the emulsion polymerization of vinyl acetate, which is additionally provided with a pulsator. EP-B 0 443 609 discloses a microsuspension process in which various monomers are emulsified in water using a high-speed stirrer which generates very high shear forces. The total amount of the microsuspension is then converted into the polymer with a particle size of 5-50 μm diameter in a stirred tank in a batchwise process.
In der prioritätsälteren nicht-vorveröff entlichten DE-A 196 33 626 wird die Polymerisation einer Mikrosuspension von unter anderem (Meth)acrylsäurede- rivaten sowie von gegebenenfalls als Comonomere einsetzbaren weiteren (Meth)acrylsäure- und Styrolderivaten vorgeschlagen. In dem dort genannten halbkontinuierlichen Verfahren wird nur ein Teil der Monomeres enthaltenden Mikrosuspension im Rührkesselreaktor vorgelegt und der Rest kontinuierlich mit fortschreitender Reaktion zudosiert.DE-A 196 33 626, which is older and has not been published in advance, proposes the polymerization of a microsuspension of, inter alia, (meth) acrylic acid derivatives and of further (meth) acrylic acid and styrene derivatives which can optionally be used as comonomers. In the semi-continuous process mentioned there, only part of the microsuspension containing monomer is placed in the stirred tank reactor and the rest is metered in continuously as the reaction proceeds.
In einem Übersichtsartikel von G. W. Poehlein et al. in Trends in Polymer Science, Vol. 1, No. 10, S. 298-302, 1993 und einem aktualisierten Artikel derselben Zeitschrift in Vol. 4, No. 6, S. 173-176, 1996 wird über kontinuierlich verlaufende Polymerisationen in Emulsionen und in Miniemulsio- nen berichtet. Mit der kontinuierlich verlaufenden Polymerisation in Miniemulsionen ist hier ein kontinuierlich gerührter Kesselreaktor gemeint, dem eine in einem rohrförmigen Vorreaktor erzeugte Miniemulsion kontinuierlich zudosiert wird.In a review by G. W. Poehlein et al. in Trends in Polymer Science, Vol. 1, No. 10, pp. 298-302, 1993 and an updated article from the same magazine in Vol. 4, No. 6, pp. 173-176, 1996 reports on continuous polymerizations in emulsions and in mini emulsions. The continuous polymerization in mini-emulsions here means a continuously stirred tank reactor to which a mini-emulsion generated in a tubular pre-reactor is metered in continuously.
Hingegen sind weder auf dem Gebiet der Miniemulsions-, noch auf dem der Mikrosuspensionspolymerisation kontinuierlich in Rohrreaktoren betriebene Verfahren bekannt.On the other hand, processes which are operated continuously in tubular reactors are not known in the field of mini-emulsion or microsuspension polymerization.
Aufgabe der vorliegenden Erfindung ist die Bereitstellung eines industriell durchführbaren Verfahrens zur Polymerisation von Mikrosuspensionen unter- schiedlicher Monomerer in einem kontinuierlich betriebenen Rohrreaktor unter Vermeidung der Nachteile des Standes der Technik.The object of the present invention is to provide an industrially feasible method for the polymerization of microsuspensions. different monomers in a continuously operated tubular reactor while avoiding the disadvantages of the prior art.
Die Lösung der Aufgabe geht aus von den bekannten Verfahren zur Her- Stellung von partikelförmigen Homo- oder Copolymerisaten mindestens eines polymerisierbaren Monomeren in Technik der Mikrosuspensionspolymerisation bei einer Temperatur von mindestens 0 °C in Anwesenheit mindestens eines hydrophoben radikalischen Polymerisationsinitiators. Das erfindungsgemäßeThe solution to the problem is based on the known processes for the production of particulate homopolymers or copolymers of at least one polymerizable monomer using the technique of microsuspension polymerization at a temperature of at least 0 ° C. in the presence of at least one hydrophobic radical polymerization initiator. The invention
Verfahren ist dann dadurch gekennzeichnet, daß die Mikrosuspension kon- tinuierlich oder diskontinuierlich hergestellt wird, die Polymerisation mit mindestens 50 % des Umsatzes in einem Rohrreaktor verläuft, die Verfah- rensprodukte einen mittleren Teilchendurchmesser d50 von weniger als 50 μm aufweisen und der Rohrreaktor aus einem Rohr oder Schlauch mit einem Verhältnis von Länge zu Durchmesser (L/D) von mindestens 20 besteht.The process is then characterized in that the microsuspension is produced continuously or batchwise, the polymerization takes place in at least 50% of the conversion in a tubular reactor, the process products have an average particle diameter d 50 of less than 50 μm and the tubular reactor consists of one Pipe or hose with a ratio of length to diameter (L / D) of at least 20.
Hierfür geeignete Monomere sind beispielsweise (Meth)acrylsäure, (Meth)acrylamid, (Meth)acrylnitril, Alkyl(meth)acrylate, Butadien, Isopren, Alkylenoxide, Styrol, substituierte Styrole, Vinylacetat und Vinylchlorid. Unter Alkyl(meth)acrylaten sind Ester der (Meth)acrylsäure mit linearen Ci- C32- oder verzweigten C3-C32-Alkylresten zu verstehen, insbesondere Methyl, Ethyl, Propyl, Isopropyl, n-Butyl, Isobutyl oder 2-Ethylhexyl. Diese Alkyl- reste können unsubstituiert oder durch funktioneile Gruppen, zum Beispiel durch Hydroxy-, Amino-, Ether-, Epoxid-, Sulfonsäuregruppen oder durch Chlor substituiert sein. Bevorzugte Monomere mit solchen funktionellen Gruppen im Alkylrest sind 2-Hydroxyethylacrylat, 2-Hydroxyethylmethacrylat, 3-Hydroxypropylacrylat, 2-Hydroxypropylmethacrylat, 4-Hydroxybutylacrylat, Ethyldiglykolacrylat, tert-Butylaminoethylmethacrylat, Diethylaminoethylacrylat, n-Butoxymethylaminomethacrylat, Glycidylmethacrylat, 2-Acrylamido-2-methyl- propansulfonsäure und 3-Chlor-2-hydroxypropylacrylat. Durch Einsatz von Monomeren mit polaren, sauren oder basischen Gruppen können den Polymerisaten bestimmte Gebrauchseigenschaften verliehen werden. So macht zum Beispiel die Mitverwendung von sauer oder basisch funktionalisierten Alkyl(meth)acrylaten die Polymerisate geeignet als Mattie- rungsmittel für thermoplastische Formmassen.Suitable monomers for this are, for example, (meth) acrylic acid, (meth) acrylamide, (meth) acrylonitrile, alkyl (meth) acrylates, butadiene, isoprene, alkylene oxides, styrene, substituted styrenes, vinyl acetate and vinyl chloride. Alkyl (meth) acrylates are esters of (meth) acrylic acid with linear Ci- C 32 - or branched C 3 -C understand 32 alkyl radicals, in particular methyl, ethyl, propyl, isopropyl, n-butyl, isobutyl or 2-ethylhexyl . These alkyl radicals can be unsubstituted or substituted by functional groups, for example by hydroxyl, amino, ether, epoxy, sulfonic acid groups or by chlorine. Preferred monomers having such functional groups in the alkyl group are 2-hydroxyethyl acrylate, 2-hydroxyethyl, 3-hydroxypropyl acrylate, 2-hydroxypropyl methacrylate, 4-hydroxybutyl acrylate, Ethyldiglykolacrylat, tert-butylaminoethyl methacrylate, diethylaminoethyl acrylate, n-Butoxymethylaminomethacrylat, glycidyl methacrylate, 2-acrylamido-2-methyl - Propanesulfonic acid and 3-chloro-2-hydroxypropyl acrylate. By using monomers with polar, acidic or basic groups, the polymers can be given certain usage properties. For example, the use of acidic or basic functionalized alkyl (meth) acrylates makes the polymers suitable as matting agents for thermoplastic molding compounds.
Wird im Polymerisationschritt die Mikrosuspension nur eines Monomeren eingesetzt, so entstehen Homopolymerisate. Zur Herstellung von Copolymerisaten kann nach der Polymerisation eines ersten Monomeren, die zur Bil- düng des sogenannten Kern des Polymerisats führt und die zweckmäßig zu mindestens 50 % abgelaufen ist, die Mikrosuspension eines weiteren Monomeren beziehungsweise eines Monomerengemischs in den Rohrreaktor gespeist werden, so daß dieses Monomere beziehungsweise diese Monomeren zum Teil schalenförmig auf den zuerst gebildeten Polymerteilchen polymeri- siert beziehungsweise polymerisieren. Dieses Verfahren kann auch mit anderen Monomeren oder Gemischen unterschiedlicher Zusammensetzung mehrmals wiederholt werden, um Teilchen mit mehreren Schalen zu erhalten.If the microsuspension of only one monomer is used in the polymerization step, homopolymers are formed. For the preparation of copolymers, after the polymerization of a first monomer, which leads to the formation of the so-called core of the polymer and which has expediently expired to at least 50%, the microsuspension of a further monomer or a monomer mixture can be fed into the tubular reactor, so that this Monomers or these monomers are partially polymerized or polymerized in shell form on the polymer particles formed first. This process can also be repeated several times with other monomers or mixtures of different compositions in order to obtain particles with several shells.
Dabei kann die Zudosierung weiterer Monomerer auch ohne vorhergehende Herstellung einer Mikrosuspension erfolgen, indem das Monomere beziehungsweise Monomerengemisch, Wasser, Suspendierhilfsmittel und gegebenenfalls weitere Zusatzstoffe direkt zudosiert werden. Ebenfalls ist es möglich, das zuvor gebildete Polymerisat erst in einen anderen Rohrreaktor zu über- führen und dann mit der Zudosierung mindestens eines weiteren Monomeren zu beginnen.Additional monomers can also be metered in without prior preparation of a microsuspension by metering in the monomers or monomer mixture, water, suspending agent and, if appropriate, other additives directly. It is also possible to first transfer the previously formed polymer to another tubular reactor and then to start metering in at least one further monomer.
Als Comonomere eignen sich bi- und poly funktioneile Monomere, beispielsweise Butadien, Isopren, Divinylester von Dicarbonsäuren wie Bernstein- und Adipinsäure, Diallyl- und Diviny lether sowie Bis-acryl- und Bis-methacryl- säureester bifunktioneller Alkohole wie Ethylenglykol und Butan- 1,4-diol, 1 ,4-Divinylbenzol und Triallyecyanurat. Besonders geeignet sind die Acryl- und Methacrylsäureester des Allylalkohols sowie der Acrylsäureester des Tricyclodecenylalkohols (Dihydrodicyclopentadieny lacrylat) .Suitable comonomers are bi- and polyfunctional monomers, for example butadiene, isoprene, divinyl esters of dicarboxylic acids such as succinic and adipic acid, diallyl and divinyl ethers, and bis-acrylic and bis-methacrylic acid esters of bifunctional alcohols such as ethylene glycol and butane-1,4-diol, 1,4-divinylbenzene and triallyecyanurate. The acrylic and methacrylic acid esters of allyl alcohol and the acrylic acid esters of tricyclodecenyl alcohol (dihydrodicyclopentadienyl acrylate) are particularly suitable.
Der Rohrreaktor kann auch in Form eines Kreislaufreaktors betrieben werden, wobei die Mikrosuspension in dem rohrförmigen Reaktor im Kreislauf gefahren und polymerisiert wird. Dabei wird ein Teil der bereits polymeri- sierten Mikrosuspension kontinuierlich dem Kreislauf entnommen und ein äquivalenter Teil neuer Mikrosuspension zudosiert. Das Verhältnis zwischen der Menge an Mikrosuspension, die in einem bestimmten Zeitintervall einen Rohrquerschnitt passiert und der Menge an Mikrosuspension, die im selben Zeitintervall dem Kreislaufreaktor zudosiert wird, ist im allgemeinen größer 5, bevorzugt größer 10 und besonders bevorzugt größer 20.The tubular reactor can also be operated in the form of a circulation reactor, the microsuspension in the tubular reactor being circulated and polymerized. Part of the already polymerized microsuspension is continuously removed from the circuit and an equivalent part of new microsuspension is metered in. The ratio between the amount of microsuspension that passes through a pipe cross-section in a certain time interval and the amount of microsuspension that is metered into the cycle reactor in the same time interval is generally greater than 5, preferably greater than 10 and particularly preferably greater than 20.
Im erfindungsgemäßen Verfahren sind, sofern nichts anderes angegeben, unter dem Ausdruck "Rohrreaktor" sowohl ein Kreislaufreaktor als auch ein nicht kreislaufbetriebener Reaktor zu verstehen.In the process according to the invention, unless stated otherwise, the expression "tubular reactor" is understood to mean both a circulation reactor and a non-circulation-operated reactor.
Gegebenenfalls kann der Rohrreaktor mit Elementen gefüllt sein, die für eine bessere radiale Durchmischung sorgen. Als Elemente eignen sich zum Beispiel Raschig-Ringe, Schikanen oder andere Einbauten und statische Mischer. Eine bessere radiale Durchmischung kann ebenfalls durch eine sogenannte pulsierende Fahrweise des Reaktors erzielt werden. Darunter versteht man in der Regel eine pulsierende Einspeisung der Mikrosuspension in den Rohrreaktor. Bevorzugt ist eine pulsierende Fahrweise mit einer Einspeisungsrate von einmal in 30 Sekunden bis zehnmal in einer Sekunde, insbesondere von einmal in 2 Sekunden bis fünfmal in einer Sekunde. Die mittlere Verweilzeit der Mikrosuspension im Rohrreaktor hängt unter anderem von den zu polymerisierenden Monomeren ab und liegt üblicherweise zwischen 10 Minuten und 10 Stunden, bevorzugt zwischen 10 Minuten und 4 Stunden.If necessary, the tubular reactor can be filled with elements which ensure better radial mixing. For example, Raschig rings, baffles or other internals and static mixers are suitable as elements. A better radial mixing can also be achieved by a so-called pulsing mode of operation of the reactor. This usually means a pulsating feeding of the microsuspension into the tubular reactor. A pulsating driving style with a feed rate of once in 30 seconds to ten times in one second is preferred, in particular from once in 2 seconds to five times in one second. The average residence time of the microsuspension in the tubular reactor depends, inter alia, on the monomers to be polymerized and is usually between 10 minutes and 10 hours, preferably between 10 minutes and 4 hours.
Die Dimensionen des Rohrreaktors richten sich nach den gewünschten Eigenschaften der herzustellenden partikelförmigen Polymerisate. Bevorzugt ist ein L/D- Verhältnis von größer 5000, insbesondere von größer 10000. Die Wahl der geeigneten Reaktordimension hängt unter anderem von der Polymerisa- tionsgeschwmdigkeit der Monomeren, von der Form des Rohres und von der Fahrweise des Reaktors ab. Bei einer im Kreislauf betriebenen Fahrweise liegt das Verhältnis L/D im allgemeinen zwischen 50 und 1000 und ist damit kleiner zu wählen als bei einer nicht kreislaufförmigen Fahrweise.The dimensions of the tubular reactor depend on the desired properties of the particulate polymers to be produced. An L / D ratio of greater than 5000, in particular greater than 10,000, is preferred. The choice of the suitable reactor dimension depends, inter alia, on the polymerization rate of the monomers, on the shape of the tube and on the mode of operation of the reactor. In a cycle mode of operation, the ratio L / D is generally between 50 and 1000 and is therefore to be chosen smaller than in a non-cycle mode of operation.
Die Wahl des Reaktormaterials hängt von der Art der zu polymerisierenden Monomeren. Bevorzugt werden nichtmetallische Materialien, zum Beispiel Polytetrafluorethylen, und metallische, zum Beispiel Stähle nach DIN 17440, die innen beschichtet sein können, zum Beispiel mit Emaille oder Polymeren, insbesondere mit fluorhaltigen Polymeren.The choice of the reactor material depends on the type of monomers to be polymerized. Non-metallic materials, for example polytetrafluoroethylene, and metallic, for example steels according to DIN 17440, which can be coated on the inside, for example with enamel or polymers, in particular with fluorine-containing polymers, are preferred.
Der Rohrreaktor kann temperiert werden, indem er in ein wärmeübertragen- des Medium taucht oder vorzugsweise einen mit einem wärmeübertragenden Medium gefüllten Doppelmantel besitzt. Solche geeignete Medien sind beispielsweise Wasser, Sole, Öle und andere Flüssigkeiten.The tubular reactor can be tempered by immersing it in a heat-transfer medium or preferably having a double jacket filled with a heat-transfer medium. Such suitable media are, for example, water, brine, oils and other liquids.
Die für die Polymerisation im Rohrreaktor gewählte Temperatur hängt im wesentlichen von der Art der eingesetzten Monomere und Polymerisationsinitiatoren und liegt in der Regel zwischen 0 und 140 °C, bevorzugt zwischen 20 und 130 °C. Selbstverständlich kann der Rohrreaktor auch mit einem Temperaturprogramm betrieben werden. So kann zum Beispiel die Polymerisation mit einer Temperatur von 70 °C begonnen und mit 100 °C beendet werden.The temperature selected for the polymerization in the tubular reactor essentially depends on the type of monomers and polymerization initiators used and is generally between 0 and 140 ° C., preferably between 20 and 130 ° C. Of course, the tubular reactor can also be operated with a temperature program. For example, the Polymerization started at a temperature of 70 ° C and ended at 100 ° C.
In bevorzugten Ausführungsformen verläuft die Polymerisation zu mindestens 60 %, insbesondere zu mindestens 80 % im Rohrreaktor. Selbstverständlich kann der Teil der noch nicht abreagierten Monomeren nach Verlassen des Rohrreaktors teilweise oder vollständig auspolymerisieren, sofern die Suspension eine für die Polymerisation noch ausreichende Temperatur aufweist. Bei nicht vollständigem Umsatz können die Polymerisate, sofern dies gewünscht ist, problemlos von den nicht umgesetzten Monomeren und gegebenenfalls von den anderen Bestandteilen der Suspension abgetrennt werden, zum Beispiel durch Sprühtrocknung oder durch Koagulation und Trocknung.In preferred embodiments, the polymerization takes place at least 60%, in particular at least 80%, in the tubular reactor. Of course, the part of the monomers which have not yet reacted completely or completely polymerize out after leaving the tubular reactor, provided the suspension is still at a temperature which is sufficient for the polymerization. If the conversion is not complete, the polymers can, if desired, be easily separated from the unreacted monomers and, if appropriate, from the other constituents of the suspension, for example by spray drying or by coagulation and drying.
Die nach dem erfindungsgemäßen Verfahren hergestellten Polymerisate weisen einen mittleren Teilchendurchmesser d50 auf, der bevorzugt zwischen 0,03 und 50 μm, insbesondere zwischen 0,1 und 30 μm liegt. Die Ermittlung des mittleren Teilchendurchmessers kann dadurch erfolgen, daß licht- oder elektronenmikroskopische Bilder angefertigt werden, und die Teilchen dann gemessen und gezählt werden. Eine weitere Methode ist die Fraunho- fer-Laserbeugung.The polymers produced by the process according to the invention have an average particle diameter d 50 , which is preferably between 0.03 and 50 μm, in particular between 0.1 and 30 μm. The mean particle diameter can be determined by taking light or electron microscopic images and then measuring and counting the particles. Another method is Fraunhofer laser diffraction.
Als Suspendierhilfsmittel eignen sich solche wasserlöslichen Verbindungen, die in der Lage sind, die feinen Monomerentröpfchen und die daraus gebildeten Polymerteilchen zu umhüllen und auf diese Weise vor einer un- erwünschten Koagulation zu schützen. Dazu zählen beispielsweise Cellulose- derivate, wie Carboxyl- und Hydroxymethylcellulose, Poly-N-viπylpyπolidin, Polyvinylalkohol und Polyethylenoxid, anionische Polymere wie Polyacrylsäu- re und deren Copolymere und kationische Polymere wie Poly-N-vinylimidazol in Konzentrationen von vorzugsweise 0,02 bis 5 Gew.-%, bezogen auf die Gesamtmasse der Mikrosuspension. Als Suspendierhilfsmittel eignen sich auch Emulgatoren wie die Alkalisalze von Aryl- und Alkylsulfonsäuren sowie von Aryl- und Alkylcarbonsäuren, beispielsweise Natriumstearat, Kaliumstearat, Natriumoleat und Kaliumoleat, sowie ethoxylierte oder propoxylierte Alkohole und Phenole. Diese Emulgatoren werden ebenfalls in Konzentrationen von vorzugsweise 0,02 bis 5 Gew.-%, bezogen auf die Gesamtmasse der Mikrosuspension, eingesetzt.Suitable suspending aids are those water-soluble compounds which are able to coat the fine monomer droplets and the polymer particles formed therefrom and in this way to protect them from undesired coagulation. These include, for example, cellulose derivatives, such as carboxyl and hydroxymethyl cellulose, poly-N-vinylpyπolidin, polyvinyl alcohol and polyethylene oxide, anionic polymers such as polyacrylic acid and their copolymers and cationic polymers such as poly-N-vinylimidazole in concentrations of preferably 0.02 to 5 % By weight, based on the total mass of the microsuspension. Also suitable as suspending aids Emulsifiers such as the alkali salts of aryl and alkyl sulfonic acids and of aryl and alkyl carboxylic acids, for example sodium stearate, potassium stearate, sodium oleate and potassium oleate, and also ethoxylated or propoxylated alcohols and phenols. These emulsifiers are also used in concentrations of preferably 0.02 to 5% by weight, based on the total mass of the microsuspension.
Besonders bevorzugt ist die Verwendung eines oder mehrerer Polyvinylalko- hole mit einem Hydrolysegrad von weniger als 96 Mol-%, bevorzugt zwi- sehen 60 und 94 Mol-%, insbesondere zwischen 65 und 92 Mol-%. Die bevorzugten Polyvinylalkohole weisen eine Viskosität von 1 bis 100 mPa/s, insbesondere von 2 bis 60 mPa/s, gemessen als 4 Gew.-%ige Lösung in Wasser bei 20° C nach DIN 53015 auf.It is particularly preferred to use one or more polyvinyl alcohols with a degree of hydrolysis of less than 96 mol%, preferably between 60 and 94 mol%, in particular between 65 and 92 mol%. The preferred polyvinyl alcohols have a viscosity of 1 to 100 mPa / s, in particular 2 to 60 mPa / s, measured as a 4% strength by weight solution in water at 20 ° C. according to DIN 53015.
Als vorteilhaft hat sich in vielen Fällen die Zugabe von kolloidaler Kieselsäure in Konzentrationen von 0,2 bis 5 Gew.-%, bezogen auf die Gesamtmenge der Mikrosuspension, herausgestellt.In many cases it has proven advantageous to add colloidal silica in concentrations of 0.2 to 5% by weight, based on the total amount of the microsuspension.
Wird die Herstellung von Teilchen mit einem Schalenaufbau gewünscht, so erfolgt nach der Polymerisation eines ersten Monomeren, die zweckmäßig zu mindestens 50 %, bevorzugt zu mindestens 75 %, insbesondere zu mindestens 85 % abgelaufen ist, die Zugabe der Mikrosuspension mindestens eines weiteren Monomeren beziehungsweise die Zugabe mindestens eines weiteren Monomeren. Dieser Schritt kann mehrfach wiederholt werden, um Polymeri- säte mit einem mehrschaligen Aufbau zu erhalten. Wie bereits oben genannt, kann die Herstellung von Copolymerisaten auch so erfolgen, daß nach der Polymerisation eines Monomeren oder Monomerengemischs dieses so hergestellte Polymerisat in einen zweiten Rohπeaktor überführt wird, und dann die Zudosierung mindestens eines weiteren Monomeren erfolgt. Selbstver- ständlich ist auch die Verwendung eines Rührkesselreaktors statt eines zweiten Rohrreaktors möglich, ebenso wie die umgekehrte Vorgehensweise, d.h. zuerst Herstellung eines Polymerisats in einem Rührkesselreaktor und dann Zudosierung mindestens eines weiteren Monomeren in einem Rohrreaktor.If the production of particles with a shell structure is desired, after the polymerization of a first monomer, which has expired expediently at least 50%, preferably at least 75%, in particular at least 85%, the microsuspension is added or at least one further monomer Addition of at least one further monomer. This step can be repeated several times in order to obtain polymers with a multi-layer structure. As already mentioned above, copolymers can also be prepared in such a way that after the polymerization of a monomer or monomer mixture, the polymer thus prepared is transferred to a second crude reactor, and then at least one further monomer is metered in. It goes without saying that a stirred tank reactor is used instead of one second tube reactor possible, as well as the reverse procedure, that is, first of all, preparation of a polymer in a stirred tank reactor and then metering in of at least one further monomer in a tube reactor.
Der Übergang vom Kern zur Schale, beziehungsweise der Übergang von einer Schale zur nächsten Schale ist dabei um so schärfer, je vollständiger ein Monomer bereits polymerisiert ist, bevor mit der Zudosierung mindestens eines weiteren Monomeren als solchem beziehungsweise in Form einer Mikrosuspension begonnen wird.The transition from the core to the shell or the transition from one shell to the next shell is sharper the more completely a monomer is already polymerized before the metering in of at least one further monomer as such or in the form of a microsuspension is started.
Darüber hinaus kann durch entsprechende Wahl der Monomere und der Reaktorbedingungen ebenfalls die Teilchenmorphologie beeinflußt werden. So können zum Beispiel neu eingespeiste Monomere nicht nur schalenartig auf die bereits fertig polymerisierten Teilchen eines zuvor eingesetzten anderen Monomer-Typs aufpolymerisieren, sondern auch zu einem beträchtlichen Anteil in diese Teilchen hineinpolymerisieren, sodaß der Kern-Schale-Aufbau weniger stark ausgeprägt ist.In addition, the particle morphology can also be influenced by appropriate selection of the monomers and the reactor conditions. For example, newly fed monomers can not only polymerize shell-like onto the already polymerized particles of a previously used other monomer type, but also polymerize into these particles to a considerable extent, so that the core-shell structure is less pronounced.
Werden vernetzend wirkende Monomere zu einem Kern oder einer Schale polymerisiert, so können noch reaktions-, d.h. polymerisationsfähige C-C- Doppelbindungen verbleiben, auf die im nächstfolgenden Polymerisationsschritt ein weiteres Monomer aufgepfropft werden kann. Solche Pfropfungs- reaktionen sind dem Fachmann bekannt.If crosslinking monomers are polymerized to form a core or a shell, then reaction, i.e. polymerizable C-C double bonds remain, onto which a further monomer can be grafted in the next polymerization step. Such grafting reactions are known to the person skilled in the art.
Als radikalischer Polymerisationsinitiator sind freie Radikale bildende Verbindungen geeignet, sofern sie öllöslich sind. Dazu zählen Peroxide, Azover- bindungen und Verbindungen mit labilen C-C-Bindungen. Sollen solche Monomere polymerisiert werden, die bei erhöhter Temperatur spontan zur Polymerisation neigen, so kann auf die Zugabe eines radikalischen Polymeri- sationsinitiators verzichtet werden. Zu dieser Gruppe Monomerer zählen insbesondere Styrol und seine Derivate.Compounds which form free radicals are suitable as radical polymerization initiators, provided they are oil-soluble. These include peroxides, azo compounds and compounds with labile CC bonds. If such monomers are to be polymerized that spontaneously tend to polymerize at elevated temperature, the addition of a radical polymer sationsinitiators be waived. This group of monomers includes in particular styrene and its derivatives.
Aus der Gruppe der Peroxide sind diejenigen mit einem Verhältnis von Kohlenstoff zu Sauerstoff von größer als 3 zu 1 wie Dilaurylperoxid, Dibenzoylperoxid, Diacetylperoxidicarbonat, Dimyristilperoxidicarbonat und Bis-(3,5,5-trimethylhexanoyl)peroxid bevorzugt, insbesondere Dilaurylperoxid. Unter den Azoverbindungen sind 2,2'-Azo-bis-(isobutyronitril) und 2,2'-Azo- bis-(2-methylbutyronitril) bevorzugt. Aus der Gruppe mit labilen C-C-Bindun- gen werden bevorzugt 3,4-Dimethyl-3,4-dipherrylhexan und 2,3-Dimethyl-2,3- diphenylbutan verwendet.From the group of peroxides, those with a ratio of carbon to oxygen of greater than 3 to 1, such as dilauryl peroxide, dibenzoyl peroxide, diacetyl peroxidicarbonate, dimyristil peroxidicarbonate and bis- (3,5,5-trimethylhexanoyl) peroxide, in particular dilauryl peroxide, are preferred. Among the azo compounds, 2,2'-azobis (isobutyronitrile) and 2,2'-azobis (2-methylbutyronitrile) are preferred. From the group with labile C-C bonds, 3,4-dimethyl-3,4-dipherrylhexane and 2,3-dimethyl-2,3-diphenylbutane are preferably used.
Diese Polymerisationsinitiatoren werden in einer Menge von 0,05 bis 4 Gew.-%, bezogen auf die Menge des Monomeren, bevorzugt 0, 1 bis 2 Gew.-%, insbesondere 0,3 bis 1,0 Gew.-% , eingesetzt. Diese Mengenangabe gilt natürlich nicht für den Fall, daß das Monomer zugleich Initiator ist. Ebenso können Mischungen der genannten Polymerisationsinitiatoren eingesetzt werden.These polymerization initiators are used in an amount of 0.05 to 4% by weight, based on the amount of the monomer, preferably 0.1 to 2% by weight, in particular 0.3 to 1.0% by weight. Of course, this quantity does not apply if the monomer is also the initiator. Mixtures of the polymerization initiators mentioned can also be used.
Je nach Aggregatzustand des Polymerisationsinitiators und seiner Löslichkeits- eigenschaften kann er als solcher, bevorzugt jedoch als Lösung, Emulsion oder Suspension entweder der zu einer Mikrosuspension zu emulgierenden Mischung, der bereits fertigen Mikrosuspension oder der im Rohπeaktor befindlichen zu polymerisierenden Mikrosuspension zudosiert werden. Als Lösungsmittel beziehungsweise als flüssige Phase für den Polymerisationsinitiator eignen sich organische Lösungsmittel, wie Benzol, Toluol, Xylol, Ethylbenzol, Cyclohexan und die Monomeren selbst.Depending on the state of aggregation of the polymerization initiator and its solubility properties, it can be added as such, but preferably as a solution, emulsion or suspension, either to the mixture to be emulsified to form a microsuspension, to the already prepared microsuspension or to the microsuspension to be polymerized in the crude reactor. Organic solvents such as benzene, toluene, xylene, ethylbenzene, cyclohexane and the monomers themselves are suitable as the solvent or as the liquid phase for the polymerization initiator.
Je nach gewünschtem Verwendungszweck der Polymerisate können der zu emulgierenden Mischung oder der bereits fertigen Mikrosuspension mehr als 0, 1 Gew.-% , bevorzugt mehr als 1 Gew.-% , insbesondere mehr als 5 Gew.- % mindestens eines Feststoffes in gelöster, gequollener oder suspendierter Form zugegeben werden. Diese Feststoffe können Polymere, farbgebende und ferromagnetische Pigmente sowie andere Substanzen, wie Mineralien, sein. Bei Verwendung von Ruß entstehen schwarze partikelförmige Polymerisate, die insbesondere als Kopier-Toner Verwendung finden. Der Einsatz von ferromagnetischen Pigmenten führt zur Bildung von partikelförmigen Polymerisaten mit ferromagnetischen Eigenschaften. Solche Polymerisate sind zur Herstellung von Magnetbändern und Magnetfolien besonders geeignet.Depending on the intended use of the polymer, the mixture to be emulsified or the already prepared microsuspension can be more than 0.1% by weight, preferably more than 1% by weight, in particular more than 5% by weight, of at least one solid in dissolved, swollen or suspended form are added. These solids can be polymers, coloring and ferromagnetic pigments as well as other substances such as minerals. When using carbon black, black particulate polymers are produced, which are used in particular as copier toners. The use of ferromagnetic pigments leads to the formation of particulate polymers with ferromagnetic properties. Such polymers are particularly suitable for the production of magnetic tapes and magnetic foils.
Wie bei Polymerisationen üblich können auch beim erfindungsgemäßen Verfahren je nach gewünschten Eigenschaften der Polymerisate weitere die Produkteigenschaften beeinflussende Zusatzstoffe zugesetzt werden. Dazu zählen - Molekulargewichtsregler, zum Beispiel t-Dodecylmerkaptan oder 2-As is customary in polymerizations, further additives which influence the product properties can also be added in the process according to the invention, depending on the desired properties of the polymers. These include - molecular weight regulators, for example t-dodecyl mercaptan or 2-
Ethylhexylthioglykolat,Ethylhexylthioglycolate,
Puffer um den pH-Wert zu regulieren, zum Beispiel Citratpuffer, Dinatriumhydrogenphosphat und Natriumdihydrogenphosphat, Inhibitoren, die den bei der Mikrosuspensionspolymerisation gleich- zeitig als unerwünschte Konkurrenzreaktion ablaufenden Prozeß derBuffers to regulate the pH value, for example citrate buffers, disodium hydrogen phosphate and sodium dihydrogen phosphate, inhibitors which simultaneously inhibit the process of microsuspension polymerization which is an undesirable competitive reaction
Emulsionspolymerisation, bei der im wesentlichen unerwünschte kleinere Polymerisate entstehen, zurückdrängen, zum Beispiel Chrom-(VI)-Salze, insbesondere Kalium- und Natriumdichromat.Emulsion polymerization, in which essentially undesirable smaller polymers are formed, is suppressed, for example chromium (VI) salts, in particular potassium and sodium dichromate.
Diese weiteren Zusatzstoffe können kontinuierlich oder diskontinuierlich zu Beginn und/oder während der Herstellung der Mikrosuspension und/oder während der Polymerisation zudosiert werden.These further additives can be metered in continuously or batchwise at the beginning and / or during the preparation of the microsuspension and / or during the polymerization.
Die in dem erfindungsgemäßen Verfahren eingesetzte Mikrosuspension wird aus Monomer, Suspendierhilfmittel, Wasser, gegebenenfalls den weiteren oben angegebenen Fest- und anderen Zusatzstoffen sowie gegebenenfalls Polymerisationsinitiator hergestellt, indem man auf die Mischung dieser Stoffe sehr hohe Scherkräfte einwirken läßt. Methoden um sehr hohe Scherkräfte ausüben zu können sind dem Fachmann bekannt.The microsuspension used in the process according to the invention is made up of monomer, suspending agent, water and, if appropriate, the others Solid and other additives specified above and optionally polymerization initiator prepared by allowing very high shear forces to act on the mixture of these substances. Methods for being able to exert very high shear forces are known to the person skilled in the art.
Sie können erzeugt werden durch intensives RührenThey can be produced by intensive stirring
Scherung mit einem Rotor-Stator-System Homogenisierung mit Ultraschall - einen Druckhomogenisator, bei dem die Mischung der zu emulgierenden Stoffe unter hohem Druck durch einen engen Spalt oder durch enge Düsen gepreßt wird.Shear with a rotor-stator system. Homogenization with ultrasound - a pressure homogenizer, in which the mixture of the substances to be emulsified is pressed under high pressure through a narrow gap or through narrow nozzles.
Als Beispiele geeigneter Rührer und Homogenisatoren seien genannt: - Labordissolver Dispermat, Fa. VMA-Getzmann, Reichshof, DEExamples of suitable stirrers and homogenizers are: Laboratory dissolver Dispermat, VMA-Getzmann, Reichshof, DE
Ultra-Turrax, Fa. Janke und Kunkel, Staufen, DE Cavitron-Homogenisator, Fa. v. Hagen & Funke, Sprockhövel, DE Homogenisatoren der Firma Kotthoff, Essen, DE Druckhomogenisator der Firma Gaulin, Lübeck, DEUltra-Turrax, from Janke and Kunkel, Staufen, DE Cavitron homogenizer, from v. Hagen & Funke, Sprockhövel, DE homogenizers from Kotthoff, Essen, DE pressure homogenizers from Gaulin, Lübeck, DE
Die Herstellung der Mikrosuspension erfolgt üblicherweise bei Raumtemperatur, kann jedoch auch je nach Art der Monomere und anderen Stoffe bei tieferer oder höherer Temperatur erfolgen.The microsuspension is usually produced at room temperature, but can also be carried out at a lower or higher temperature, depending on the type of monomers and other substances.
Die Rührer werden üblicherweise mit Drehzahlen zwischen 1000 und 25000 Umdrehungen pro Minute (Upm), vorzugsweise zwischen 2000 und 15000 Upm bei einer Rührzeit, die zwischen 0,1 Sekunden und mehreren Stunden liegen kann, betrieben. Üblicherweise beträgt die Menge Wasser, in dem die Monomere und die Suspendierhilfsmittel dispergiert werden, 15 bis 95 Gew.-%, bevorzugt 35 bis 85 Gew.-%, und besonders bevorzugt 40 bis 75 Gew.-%, bezogen jeweils auf die Summe aus Monomeren, Wasser und Suspendierhilfsmittel.The stirrers are usually operated at speeds between 1000 and 25000 revolutions per minute (rpm), preferably between 2000 and 15000 rpm, with a stirring time which can be between 0.1 seconds and several hours. The amount of water in which the monomers and the suspending aids are dispersed is usually from 15 to 95% by weight, preferably from 35 to 85% by weight, and particularly preferably from 40 to 75% by weight, based in each case on the total Monomers, water and suspending agents.
Die Herstellung der Mikrosuspension erfolgt entweder diskontinuierlich oder kontinuierlich. Bei der erstgenannten Methode wird die Mischung der zu emulgierenden Stoffe in einem Behälter mit einem der oben genannten Rührer oder Homogenisatoren zur Mikrosuspension verarbeitet. Der Homoge- nisator kann auch parallel zum Behälter angeordnet sein, und die Mischung wird dann im Kreis durch den Homogenisator geführt. Bei der zweitgenannten Methode werden die zu emulgierenden Stoffe dem Homogenisator kontinuierlich zugeführt, und die entstehende Mikrosuspension wird dann ebenso kontinuierlich dem Rohrreaktor zugeführt.The microsuspension is produced either batchwise or continuously. In the former method, the mixture of the substances to be emulsified is processed in a container with one of the stirrers or homogenizers mentioned above to form the microsuspension. The homogenizer can also be arranged parallel to the container and the mixture is then circulated through the homogenizer. In the second-mentioned method, the substances to be emulsified are fed continuously to the homogenizer, and the microsuspension formed is then also fed continuously to the tubular reactor.
Die kontinuierliche Herstellweise der Mikrosuspension kann auch so ausgeführt werden, daß nur ein Teil der Mikrosuspension dem Rohrreaktor zugeführt wird und der Rest erneut den Homogenisator passiert. Diese Kreisfahrweise empfiehlt sich vor allem dann, wenn bei einem einmaligen Durchsatz durch den Homogenisator die absolute Tröpfchengröße oder die Größenverteilung der Tröpfchen unbefriedigend sein sollte.The continuous preparation of the microsuspension can also be carried out in such a way that only a part of the microsuspension is fed to the tubular reactor and the rest passes through the homogenizer again. This circular mode of operation is particularly recommended if the absolute droplet size or the size distribution of the droplets should be unsatisfactory with a single throughput through the homogenizer.
Für eine industrielle Anwendung ist auch die Kombination der beiden genannten Herstellmethoden vorteilhaft: Darunter ist zu verstehen, daß die zu emulgierenden Stoffe in einem ersten Schritt diskontinuierlich emulgiert werden, dann in einem zweiten Schritt kontinuierlich durch einen Homogenisator gefahren und in den Rohrreaktor eingespeist werden. Diese Kombination bietet den VorteilThe combination of the two production methods mentioned is also advantageous for industrial use: this means that the substances to be emulsified are emulsified discontinuously in a first step, then continuously passed through a homogenizer in a second step and fed into the tubular reactor. This combination offers the advantage
- Mikrosuspensionen hoher und gleichmäßiger Qualität herzustellen die flächenintensive diskontinuierliche Herstellung der Mikrosuspension von der eigentlichen Polymerisation räumlich zu trennen und die Mikrosuspension dem Rohrreaktor bedarfsgerecht zuzuführen.- To produce microsuspensions of high and uniform quality Separate the area-intensive, discontinuous production of the microsuspension from the actual polymerization and feed the microsuspension to the tube reactor as required.
Nach Beendigung der Polymerisation liegen die partikelförmigen Polymerisate in Wasser dispergiert vor und können, falls erforderlich, direkt sprühgetrocknet oder nach Abtrennung der wässrigen Phase, zum Beispiel durch Sieben, Filtrieren, Dekantieren oder Zentrifugieren, in üblicher Weise weiter getrocknet werden, zum Beispiel durch Warmluft oder mit Hilfe eines Stromtrock- ners. Je nach gewünschtem Verwendungszweck kann diese Polymerisat enthaltende Dispersion, die im allgemeinen eine Viskosität von 100-500 mPa/s aufweist, auch als solche weiterverarbeitet werden.After the end of the polymerization, the particulate polymers are dispersed in water and, if necessary, can be spray-dried directly or, after separation of the aqueous phase, for example by sieving, filtering, decanting or centrifuging, can be dried further in the customary manner, for example by warm air or with the help of a power dryer. Depending on the intended use, this polymer-containing dispersion, which generally has a viscosity of 100-500 mPa / s, can also be further processed as such.
Im Vergleich zum Stand der Technik ermöglicht das erfindungsgemäße Verfahren eine stabile, d.h. ohne Verstopfung des Reaktors verlaufende Fahrweise. Dies trifft auch für sehr lange Betriebszeiten des Rohrreaktors zu, die ein vielfaches der mittleren Verweilzeit der Mikrosuspension im Rohrreaktor betragen. Die eingesetzte Mikrosuspension neigt unter den gewählten Reaktionsbedingungen nicht zu Koagulationserscheinungen. Die erfindungsgemäß hergestellten Homo- und Copolymerisate weisen gute anwendungstechnische Eigenschaften auf. Sie finden beispielsweise Verwendung als Zusatzstoffe für thermoplastische Formmassen, als Bestandteile von Kopier- Tonern, Papier- und Lederhilfsmitteln, Beschichtung für Magnetbänder und Magnetfolien und als Färb- und Anstrichmittelkomponenten.In comparison to the prior art, the method according to the invention enables a stable, i.e. Operation without blockage of the reactor. This also applies to very long operating times of the tubular reactor, which are a multiple of the average residence time of the microsuspension in the tubular reactor. The microsuspension used does not tend to show signs of coagulation under the chosen reaction conditions. The homopolymers and copolymers prepared according to the invention have good performance properties. They are used, for example, as additives for thermoplastic molding compositions, as constituents of copier toners, paper and leather auxiliaries, coatings for magnetic tapes and magnetic foils, and as coloring and coating components.
Die nachfolgenden Beispiele erläutern die Erfindung näher. BeispieleThe following examples explain the invention in more detail. Examples
Zur Durchführung der Versuche wurden folgende Stoffe eingesetzt:The following substances were used to carry out the tests:
Es wurde entionisiertes Wasser verwendet.Deionized water was used.
Acrylnitril, Butylacrylat, Dihydrodicyclopentadienylacrylat und Styrol sind Produkte der BASF AG, Ludwigshafen, DE und wurden ohne weitere Reinigung verwendet. Die Polyvinylalkohole vom Typ Mowiol® sind Produkte der Hoechst AG, Frankfurt am Main, DE. Die erste Zahl hinter dem Markenname gibt die Viskosität einer 4 gew. -% igen Lösung des Polyvinylalkohols in Wasser bei 20 ° C in [mPa/s], gemessen nach DIN 53015 an. Die zweite Zahl charakterisiert den Hydrolysegrad des Polyvinylalkohols in mol %. Die Polymerisationsinitiatoren sind handelsübliche Produkte.Acrylonitrile, butyl acrylate, dihydrodicyclopentadienyl acrylate and styrene are products of BASF AG, Ludwigshafen, DE and were used without further purification. The Mowiol ® polyvinyl alcohols are products of Hoechst AG, Frankfurt am Main, DE. The first number after the brand name indicates the viscosity of a 4 wt. -% solution of the polyvinyl alcohol in water at 20 ° C in [mPa / s], measured according to DIN 53015. The second number characterizes the degree of hydrolysis of the polyvinyl alcohol in mol%. The polymerization initiators are commercially available products.
Beispiel 1example 1
Zur Herstellung eines Homopolymerisats wurde in einem Behälter eine Mi- schung ausA mixture was made in a container to produce a homopolymer
784,0 g Butylacrylat 16,0 g Dihydrodicyclopentadienylacrylat 1500,0 g Wasser 160,0 g einer 10 gew.-%igen Lösung des Polyvinylalkohols Mowiol® 8/88 in Wasser und 6,4 g Dilaurylperoxid vorgelegt und mit einem Homogenisator des Typs Dispermat CV der Fa. Getzmann 20 Minuten bei einer Drehzahl von 7000 Upm zu einer Mikrosuspension emulgiert. Diese Mikrosuspension wurde dann mit Hilfe einer Kolbenpumpe Typ KP 2000 der Fa. Desaga, Heidelberg, DE in einen aus Polytetrafluorethylen bestehenden Rohrreaktor mit einem L/D-Verhältnis von 8300 und einem Innendurchmesser von 3 mm dosiert. Die Dosiergeschwindigkeit betrug 500 ml/h. Die Temperatur des Reaktorinhalts wurde mit Hilfe eines Wasserbades auf 75 °C gehalten. Nach 20 minütiger mittlerer Verweilzeit im Rohrreaktor wurde die polymerisierte Suspension gesammelt. Der Rohrreaktor wurde insgesamt 5 Stunden und 45 Minuten unter diesen Bedingungen betrieben. Die Suspension zeigte kein Koagulat und der Rohrreaktor zeigte keine Anzeichen von Verstopfung. Der Feststoffanteil betrug 33 Gew.-%. Der mittlere Teilchendurchmesser d50 betrug 2,5 μm.784.0 g butyl acrylate 1500.0 g water, 16.0 g of dihydrodicyclopentadienyl 160.0 g of a 10 wt .-% solution of the polyvinyl alcohol Mowiol ® 8/88 in water and 6.4 g of dilauryl presented and emulsified for 20 minutes at a speed of 7000 rpm with a Dispermat CV homogenizer from Getzmann to a microsuspension. This microsuspension was then metered into a tube reactor consisting of polytetrafluoroethylene with an L / D ratio of 8300 and an inner diameter of 3 mm with the aid of a KP 2000 piston pump from Desaga, Heidelberg, DE. The metering rate was 500 ml / h. The temperature of the reactor contents was kept at 75 ° C. using a water bath. After an average residence time of 20 minutes in the tubular reactor, the polymerized suspension was collected. The tubular reactor was operated for a total of 5 hours and 45 minutes under these conditions. The suspension showed no coagulum and the tubular reactor showed no signs of clogging. The solids content was 33% by weight. The average particle diameter d 50 was 2.5 μm.
Beispiel 2Example 2
Zur Herstellung eines Copolymerisats wurde der Versuch aus Beispiel 1 wiederholt und die so hergestellte Butylacrylatpolymerisat enthaltende Suspension wurde in einen zweiten Rohπeaktor dosiert, der dieselben Dimensionen und dieselbe Materialzusammensetzung aufwies wie der in Beispiel 1. Bei einer Temperatur von 75 °C wurden die beiden unten angegebenen Mischungen A und B getrennt in kontinuierlicher Weise zudosiert. Die Dosierrate wurde so gewählt, daß das Gewichtsverhältnis der Mischung B zu Polybutylacrylat 20 zu 80 betrug.To prepare a copolymer, the experiment from Example 1 was repeated and the suspension containing butyl acrylate polymer thus prepared was metered into a second crude reactor which had the same dimensions and the same material composition as that in Example 1. At a temperature of 75 ° C., the two given below were given Mixtures A and B are metered in separately in a continuous manner. The metering rate was chosen so that the weight ratio of mixture B to polybutyl acrylate was 20 to 80.
A: 600,0 g WasserA: 600.0 g water
264,2 g einer 10 gew.- igen Lösung des Polyvinylalkohols Mowiol® 8/88 in Wasser B: 495,5 g Styrol 165, 1 g Acrylnitril8/88 264.2 g of a 10 wt solution of the polyvinyl alcohol Mowiol ® in water B: 495.5 g styrene 165, 1 g acrylonitrile
Nach 20 minütiger mittlerer Verweilzeit wurde die polymerisierte Suspension gesammelt. Der Rohπeaktor wurde insgesamt 5 Stunden unter diesen Bedingungen betrieben. Die Suspension zeigte kein Koagulat und der Rohπeaktor zeigte keine Anzeichen von Verstopfung. Der mittlere Teilchendurchmesser d50 betrug 2 μm. After an average residence time of 20 minutes, the polymerized suspension was collected. The crude reactor was operated for a total of 5 hours under these conditions. The suspension showed no coagulum and the crude reactor showed no signs of constipation. The average particle diameter d 50 was 2 μm.

Claims

Patentansprüche claims
1. Verfahren zur Herstellung von partikelförmigen Homo- und Copolymerisaten mindestens eines polymerisierbaren Monomeren in Technik der Mikrosuspensionspolymerisation bei einer Temperatur von mindestens 0°C in Anwesenheit mindestens eines hydrophoben radikalischen Polymerisationsinitiators, dadurch gekennzeichnet, daß die aus der kontinuierlich oder diskontinuierlich hergestellten Mikrosuspension eines oder mehrerer Monomerer mit mindestens 50% Umsatz in einem Rohπeaktor entstehenden partikelförmigen Homo- oder Copolymerisate einen mitt- leren Teilchendurchmesser d50 von weniger als 50 μm aufweisen und der dabei verwendete Rohπeaktor aus einem Rohr oder Schlauch mit einem Verhältnis von Länge zu Durchmesser von mindestens 20 besteht.1. A process for the preparation of particulate homopolymers and copolymers of at least one polymerizable monomer using the technique of microsuspension polymerization at a temperature of at least 0 ° C. in the presence of at least one hydrophobic radical polymerization initiator, characterized in that one or more of the microsuspension produced continuously or discontinuously Monomers with at least 50% conversion in a crude reactor, particulate homopolymers or copolymers have an average particle diameter d 50 of less than 50 μm and the crude reactor used consists of a tube or hose with a ratio of length to diameter of at least 20.
2. Verfahren nach Anspruch 1 , dadurch gekennzeichnet, daß die partikel- förmigen Homo- und Copolymerisate einen mittleren Teilchendurchmesser d50 aufweisen, der zwischen 0,03 und 50 μm liegt.2. The method according to claim 1, characterized in that the particulate homopolymers and copolymers have an average particle diameter d 50 which is between 0.03 and 50 microns.
3. Verfahren nach Anspruch 1 oder 2, dadurch gekennzeichnet, daß die Polymerisationstemperatur bei 20 bis 130 °C liegt.3. The method according to claim 1 or 2, characterized in that the polymerization temperature is 20 to 130 ° C.
4. Verfahren nach einem der Ansprüche 1 bis 3, dadurch gekennzeichnet, daß das Monomer mindestens eines aus der Gruppe Alkyl(meth)acrylat, (Meth)acrylnitril und Styrol ist. 4. The method according to any one of claims 1 to 3, characterized in that the monomer is at least one from the group alkyl (meth) acrylate, (meth) acrylonitrile and styrene.
5. Verfahren nach einem der Ansprüche 1 bis 4, dadurch gekennzeichnet, daß die Polymerisation in einem als Kreislaufreaktor ausgelegten Rohπeaktor durchgeführt wird.5. The method according to any one of claims 1 to 4, characterized in that the polymerization is carried out in a Rohπeaktor designed as a circulation reactor.
6. Verfahren nach einem der Ansprüche 1 bis 5, dadurch gekennzeichnet, daß das Länge zu Durchmesser Verhältnis des Rohπeaktors im Falle einer kreislaufbetriebenen Fahrweise zwischen 50 und 1000 und im Falle einer nicht-kreislaufbetriebenen Fahrweise größer 5000 ist.6. The method according to any one of claims 1 to 5, characterized in that the length to diameter ratio of the Rohπeaktors in the case of a cycle-driven mode of operation between 50 and 1000 and in the case of a non-cycle-operated mode of operation is greater than 5000.
7. Verfahren nach einem der Ansprüche 1 bis 6, dadurch gekennzeichnet, daß die Polymerisation bis zu einem Umsatz von mindestens 50 % , bezogen auf die eingesetzten Monomere, geführt wird, und dann weiteres Monomer oder Monomerengemisch zudosiert wird und polymerisiert.7. The method according to any one of claims 1 to 6, characterized in that the polymerization is carried out up to a conversion of at least 50%, based on the monomers used, and then further monomer or monomer mixture is metered in and polymerized.
8. Verfahren nach Anspruch 7, dadurch gekennzeichnet, daß partikelförmige Copolymerisate mit einem Kern-Schale-Aufbau entstehen.8. The method according to claim 7, characterized in that particulate copolymers are formed with a core-shell structure.
9. Verfahren nach einem der Ansprüche 1 bis 8, dadurch gekennzeichnet, daß vor oder nach der Herstellung der Mikrosuspension mehr als 0, 1 Gew.-% Polymeres, farbgebende oder feπomagnetische Pigmente oder andere Substanzen als Zusatzstoffe in gelöster, gequollener oder suspendierter Form zugegeben werden. 9. The method according to any one of claims 1 to 8, characterized in that before or after the preparation of the microsuspension more than 0.1% by weight of polymer, coloring or feπomagnetic pigments or other substances are added as additives in dissolved, swollen or suspended form become.
EP98925480A 1997-04-28 1998-04-24 Method for producing homopolymerizates and copolymerizates Withdrawn EP0977783A1 (en)

Applications Claiming Priority (3)

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DE19717877 1997-04-28
DE19717877A DE19717877A1 (en) 1997-04-28 1997-04-28 Process for the production of particulate homopolymers and copolymers from microsuspensions in a tubular reactor
PCT/EP1998/002429 WO1998049204A1 (en) 1997-04-28 1998-04-24 Method for producing homopolymerizates and copolymerizates

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EP0977783A1 true EP0977783A1 (en) 2000-02-09

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US10640591B2 (en) 2014-12-05 2020-05-05 Nippon Shokubai Co., Ltd. Method for producing water-absorbent resin

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EP1411076A1 (en) * 2002-10-15 2004-04-21 Rohm And Haas Company Continuous production of crosslinked polymer nanoparticles
FR2879207B1 (en) * 2004-12-10 2007-07-06 Commissariat Energie Atomique METHOD AND DEVICE FOR MANUFACTURING POLYMER FOAM BALLS OR BALLOONS
US8378039B2 (en) * 2008-11-21 2013-02-19 Lg Chem, Ltd. Method and apparatus for manufacturing polymer particle
JP5399809B2 (en) * 2009-08-11 2014-01-29 株式会社日本触媒 Method for producing core-shell particles and core-shell particles
JP2012092249A (en) * 2010-10-28 2012-05-17 Osaka Prefecture Univ Particulate polymer, and method for producing the same
KR102376802B1 (en) * 2018-12-10 2022-03-21 주식회사 엘지화학 Method for preparing thermoplastic copolymer, thermoplastic copolymer produced by the method and thermoplastic resin composition comprising the copolymer

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DE3222002A1 (en) * 1982-06-11 1983-12-15 Röhm GmbH, 6100 Darmstadt CONTINUOUS EMULSION POLYMERIZATION PROCESS

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* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
US10640591B2 (en) 2014-12-05 2020-05-05 Nippon Shokubai Co., Ltd. Method for producing water-absorbent resin

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CN1253568A (en) 2000-05-17
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KR20010012124A (en) 2001-02-15
JP2001522394A (en) 2001-11-13

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