Polymer manufacturing method

Abstract

The present invention relates to the preparation of polymers in the presence of a dispersing agent mixture and to the use of a dispersing agent mixture for preparing polymers in order to produce ion exchangers therefrom.

Description

[Technical Field]

[0001] The present invention relates to the preparation of polymers in the presence of a dispersant mixture and the use of a dispersant mixture for preparing polymers in order to make ion exchangers from the polymers. [Background technology]

[0002] It is known that polymers can be prepared, for example, from vinyl aromatic compounds, such as styrene, in combination with crosslinking agents, such as divinylbenzene, by suspension polymerization.

[0003] In suspension polymerization, a monomer phase containing a monomer-soluble initiator is partitioned as droplets into a substantially monomer-immiscible phase and cured by increasing the temperature. The immiscible phase is usually an aqueous phase, which may contain additives such as salts, dispersants, or protective colloids, or other water-soluble organic compounds, also referred to as the continuous phase. The mixture of the selected water-insoluble monomer and the additives and initiator dissolved therein forms the dispersed phase.

[0004] In addition to polymers in gel form, macroporous polymers can also be produced by suspension polymerization using porogens such as high-boiling aliphatic hydrocarbons, alcohols, ethers, nitro compounds, or esters.

[0005] It is known from (Non-Patent Document 1) that during suspension polymerization of methyl methacrylate, some emulsion polymerization also occurs at the same time, resulting in the formation of an undesirable polymer fine particle fraction. The polymer fine particle fraction formed by emulsion polymerization can be reduced by adding a free radical inhibitor soluble in the aqueous phase.

[0006] Patent Document 1 discloses a process for preparing bead polymers in gel form with a reduced content of soluble polymers, in which a peroxyester is used as an initiator to reduce the soluble fraction. [Prior art documents] [Patent documents]

[0007] [Patent Document 1] European Patent Application Publication No. A-0964002 [Non-patent literature]

[0008] [Non-Patent Document 1] F. Jahanzad, S. Sajjadi, B. Brooks, Polymer, 2013, 54, 16-23 Summary of the Invention [Problem to be solved by the invention]

[0009] In view of the known prior art, there remains a need for a process that can reduce the polymer fine particle fraction when preparing macroporous polymers. [Means for solving the problem]

[0010] It has now surprisingly been discovered that the polymer fines fraction can be reduced when certain dispersant mixtures are used during polymerization.

[0011] Accordingly, the present invention provides a process for preparing a polymer, comprising reacting at least one monoethylenically unsaturated compound and at least one multiethylenically unsaturated compound in the presence of at least one initiator, in the presence of water, in the presence of a porogen, and a) at least one hydroxyalkyl methylcellulose having a number average molecular weight of 80,000 g / mol to 110,000 g / mol; b) at least one hydroxyalkyl methylcellulose having a number average molecular weight of 25,000 g / mol to 42,000 g / mol; The present invention provides a process for reacting a dispersant mixture comprising: DETAILED DESCRIPTION OF THE INVENTION

[0012] The term "molecular weight" as used herein refers to number average molecular weight unless expressly stated or specified otherwise.

[0013] As the hydroxyalkyl methylcellulose of a), it is preferred to use hydroxypropyl methylcellulose and / or hydroxyethyl methylcellulose having a molecular weight of 80,000 g / mol to 110,000 g / mol.

[0014] As the hydroxyalkyl methylcellulose of b), it is preferred to use hydroxypropyl methylcellulose and / or hydroxyethyl methylcellulose having a molecular weight of 25,000 g / mol to 42,000 g / mol.

[0015] In a), it is preferred to use 2-hydroxypropylmethylcellulose having a degree of 2-hydroxypropyl substitution of 3 to 15 mol %, a degree of methoxy substitution of 26 to 31 mol % and a molecular weight of 80000 g / mol to 110000 g / mol.

[0016] In a), it is preferable to use hydroxyethyl methylcellulose having a degree of methoxy substitution of 26 to 31 mol %, a degree of hydroxyethoxy substitution of 5 to 15 mol % and a molecular weight of 80000 g / mol to 110000 g / mol.

[0017] In b), it is preferred to use 2-hydroxypropyl methylcellulose having a degree of 2-hydroxypropyl substitution of 3 to 15 mol % and a degree of methoxy substitution of 18 to 25 mol % and a molecular weight of 25000 g / mol to 42000 g / mol.

[0018] In b), it is preferred to use hydroxyethyl methylcellulose having a degree of methoxy substitution of 18 to 25 mol %, a degree of hydroxyethoxy substitution of 5 to 15 mol % and a molecular weight of 25000 g / mol to 42000 g / mol.

[0019] It is particularly preferred to use a mixture containing a) 2-hydroxypropyl methylcellulose having a degree of 2-hydroxypropyl substitution of 3 to 15 mol%, a degree of methoxy substitution of 26 to 31 mol%, and a molecular weight of 80,000 g / mol to 110,000 g / mol, and b) 2-hydroxypropyl methylcellulose having a degree of 2-hydroxypropyl substitution of 3 to 15 mol%, a degree of methoxy substitution of 18 to 25 mol%, and a molecular weight of 25,000 g / mol to 42,000 g / mol.

[0020] It is very particularly preferable to use mixtures comprising a) 2-hydroxypropyl methylcellulose having a degree of 2-hydroxypropyl substitution of 3 to 8 mol %, a degree of methoxy substitution of 26 to 31 mol % and a molecular weight of 80,000 g / mol to 110,000 g / mol, and b) 2-hydroxypropyl methylcellulose having a degree of 2-hydroxypropyl substitution of 6 to 13 mol %, a degree of methoxy substitution of 18 to 25 mol % and a molecular weight of 25,000 g / mol to 42,000 g / mol.

[0021] The hydroxyalkyl methylcelluloses of a) and b) are known and can be prepared by generally known processes, for example by reacting cellulose with an alkali metal hydroxide and then with an alkyl halide.

[0022] Hydroxyalkyl methylcelluloses are also commercially available. Particularly preferred for use as hydroxyalkyl methylcelluloses a) are Methocel® F4M (2-hydroxypropyl methylcellulose with a molecular weight of 95,000 g / mol) (DOW Chemical Company) (CAS number 9004-65-3), Walocel® VPM4937 (CAS number 9032-42-2) (hydroxyethyl methylcellulose with a molecular weight of 100,000 g / mol) and Tylose® E707002 (CAS number 9004-65-3) (2-hydroxypropyl methylcellulose with a molecular weight of 95,000 g / mol), or mixtures of these compounds.

[0023] Particularly preferred for use as b) the hydroxyalkyl methylcellulose are Methocel® K100 (2-hydroxypropyl methylcellulose with a molecular weight of 33,500 g / mol) (CAS number 9004-65-3) and Metolose® 90SH-100 (CAS number 9004-65-3) (2-hydroxypropyl methylcellulose with a molecular weight of 33,000 g / mol) or mixtures of these compounds.

[0024] The 2-hydroxypropyl methylcellulose preferably used in a) has a degree of 2-hydroxypropyl substitution of 3 to 15 mol %, a degree of methoxy substitution of 26 to 31 mol %, and a molecular weight of 80,000 g / mol to 110,000 g / mol, and preferably has a viscosity of 3,000 to 9,000 mPas.

[0025] The hydroxyethyl methyl cellulose preferably used in a) having a degree of methoxy substitution of 26 to 31 mol %, a degree of hydroxyethoxy substitution of 5 to 15 mol % and a molecular weight of 80,000 to 110,000 g / mol preferably has a viscosity of 3,000 to 9,000 mPas.

[0026] The 2-hydroxypropyl methylcellulose preferably used in b) has a degree of 2-hydroxypropyl substitution of 3 to 15 mol %, a degree of methoxy substitution of 18 to 25 mol %, and a molecular weight of 25,000 g / mol to 42,000 g / mol, and preferably has a viscosity of 80 to 500 mPas.

[0027] Preferably, in b), the hydroxyethyl methyl cellulose having a degree of methoxy substitution of 18 to 25 mol %, a degree of hydroxyethoxy substitution of 7 to 10 mol % and a molecular weight of 25000 to 42000 g / mol preferably has a viscosity of 80 to 500 mPas.

[0028] The 2-hydroxypropylmethylcellulose and hydroxyethylmethylcellulose used in a) and b) preferably have a heat gelling temperature of more than 60°C.

[0029] The hydroxyalkyl methylcelluloses a) and b) can be mixed with each other in any ratio. The weight ratio of the hydroxyalkyl methylcelluloses a) and b) is preferably 3:1 to 1:1.

[0030] The total concentration of the hydroxyalkyl methylcelluloses a) and b) is preferably 0.15 to 0.3% by weight based on the aqueous phase.

[0031] The molar substitution of hydroxypropyl and methoxy groups of 2-hydroxypropylmethylcellulose is determined in accordance with ASTM D-2363-72 / USA.

[0032] The molar substitution of the methoxy group of hydroxyethyl methylcellulose is determined in accordance with ASTM D-1347-72 / USA.

[0033] The molar substitution of the hydroxyethoxy groups of the hydroxyethyl methylcellulose is determined in accordance with ASTM D-2364-75 / USA.

[0034] The molar substitution is1 H NMR and 13 It can be further determined by C NMR spectroscopy.

[0035] The molecular weight of hydroxyalkylmethylcellulose can be determined by the method described in Journal of Polymer Science and Technology, 39(4), 293-298 (1982).

[0036] The heat gelling temperature can be determined in accordance with paragraph

[0028] of EP B1-1983004.

[0037] The viscosity of the hydroxyalkyl methyl cellulose can be determined by a common method known to those skilled in the art, preferably by a common method using a rotational viscometer at 25°C.

[0038] The 2-hydroxypropyl methylcellulose is preferably poly(O-2-hydroxypropyl, O-methyl) cellulose (CAS number 9004-65-3).The hydroxyethyl methylcellulose is preferably 2-hydroxyethyl methylcellulose (CAS number 9032-42-2).

[0039] In the process according to the present invention, hydroxyalkyl methylcelluloses a) and b) can be added separately to the reaction mixture. However, the hydroxyalkyl celluloses can be mixed first and then added to the reaction mixture, or the hydroxyalkyl methylcelluloses can be charged first as a mixture, and the buffer substance, monomer, crosslinker, porogen, and initiator can be added. This can be done sequentially or as a mixture. It is preferred that the hydroxyalkyl methylcelluloses a) and b) are mixed first and charged first. Then, it is preferred to add the buffer substance. Then, it is preferred to add the monoethylenic and polyethylenic compounds, porogen, and initiator as a mixture to the hydroxyalkyl methylcellulose.

[0040] In the process according to the invention, at least one monoethylenically unsaturated compound and at least one polyethylenically unsaturated compound are used.

[0041] However, it is also possible to use mixtures of two or more monoethylenically unsaturated compounds and mixtures of two or more polyethylenically unsaturated compounds.

[0042] For the purposes of the present invention, a monoethylenically unsaturated compound (monomer) is a compound having one free-radically polymerizable C=C double bond per molecule. Preferred compounds of this type include aromatic monoethylenically unsaturated compounds, such as vinyl and vinylidene derivatives of benzene and naphthalene, such as, preferably, vinylnaphthalene, vinyltoluene, ethylstyrene, α-methylstyrene, chlorostyrene, and preferably styrene, as well as non-aromatic vinyl and vinylidene compounds, such as, preferably, acrylic acid, methacrylic acid, C1-C8 alkyl acrylates, C1-C8 alkyl methacrylates, acrylonitrile, methacrylonitrile, acrylamide, methacrylamide, vinyl chloride, vinylidene chloride, and vinyl acetate. Non-aromatic monoethylenically unsaturated compounds are preferably used in smaller amounts, preferably 0.1% to 50% by weight, particularly preferably 0.5% to 20% by weight, based on the aromatic monoethylenically unsaturated compounds. It is preferred to use only aromatic monoethylenically unsaturated compounds.

[0043] The monoethylenically unsaturated compound is preferably used in an amount of more than 50% by weight, based on the mixture of the monoethylenically unsaturated compound and the polyethylenically unsaturated compound, particularly preferably in an amount of 80% to 98% by weight, based on the mixture of the monoethylenically unsaturated compound and the polyethylenically unsaturated compound.

[0044] For the purposes of the present invention, aromatic monoethylenically unsaturated compounds that are preferably used in the process according to the invention are styrene, vinyltoluene, ethylstyrene, α-methylstyrene, chlorostyrene, or chloromethylstyrene.

[0045] It is particularly preferable to use styrene or a mixture of styrene with the above-mentioned monomers, preferably ethylstyrene.

[0046] The polyethylenically unsaturated compound is a compound containing two or more, preferably two to four, free-radically polymerizable C=C double bonds per molecule. Preferred aromatic polyethylenically unsaturated compounds are divinylbenzene, divinyltoluene, trivinylbenzene, divinylnaphthalene, triallyl cyanurate, triallyl isocyanurate, and trivinylnaphthalene. Preferred non-aromatic polyethylenically unsaturated compounds are diethylene glycol vinyl ether, octa-1,7-diene, hexa-1,5-diene, ethylene glycol dimethacrylate, triethylene glycol dimethacrylate, trimethylolpropane trimethacrylate, allyl methacrylate, and N,N'-methylenebisacrylamide. It is particularly preferred that the polyethylenically unsaturated compound used be divinylbenzene. For most applications, commercially available grades of divinylbenzene containing ethylvinylbenzene in addition to divinylbenzene isomers are sufficient.

[0047] For the purposes of the present invention, preferred polyethylenically unsaturated compounds in the process according to the invention are divinylbenzene, divinyltoluene, trivinylbenzene, divinylnaphthalene, triallyl cyanurate, triallyl isocyanurate or trivinylnaphthalene. It is particularly preferred to use divinylbenzene.

[0048] The polyethylenically unsaturated compound is preferably used in an amount of 1% to 20% by weight, particularly preferably 2% to 12% by weight, and particularly preferably 4% to 10% by weight, based on the amount of the monoethylenically unsaturated compound. The type of polyethylenically unsaturated compound (crosslinker) is selected with reference to the subsequent use of the polymer.

[0049] Macroporous polymers are formed by adding at least one porogen to monoethylenically unsaturated and polyethylenically unsaturated compounds during polymerization to create a macroporous structure in the polymer. Particularly preferred porogens are hexane, octane, isooctane, isododecane, pentamethylheptane, methyl ethyl ketone, butanol, or octanol, and their isomers. Isododecane is very particularly preferred for use as a porogen. Particularly suitable are organic substances, such as aliphatic hydrocarbons, that dissolve in the monoethylenically unsaturated compound but are poor solvents or poor swelling agents (precipitants for the polymer) for the polymer. Macroporous polymers are preferably prepared in a range of 20 to 100 m / s. 2 / g of BET surface area.

[0050] The porogen is preferably used in an amount of 25% to 45% by weight based on the amount of the organic phase.

[0051] The polymers prepared by the process according to the present invention can be prepared in heterodisperse or monodisperse form.

[0052] The suspension polymerization that is the basis of this process preferably gives heterodisperse polymers.

[0053] The heterodisperse polymer is preferably prepared by the process according to the present invention.

[0054] Macroporous polystyrene-divinylbenzene copolymers are particularly preferably prepared by the above-described preparation process.

[0055] The scope of the present invention encompasses all definitions of radicals, parameters and explanations detailed above and below and mentioned in general terms or as within preferred ranges, including any combinations between each other, i.e., the respective ranges and preferred ranges.

[0056] In a preferred embodiment of the present invention, microencapsulated monomer droplets are preferably used for the preparation of monodisperse polymers in the process according to the present invention.

[0057] Materials useful for microencapsulation of monomer microdroplets are those known for use as complex coacervates, particularly polyesters, natural and synthetic polyamides, polyurethanes, or polyureas.

[0058] It is preferred to use gelatin as a natural polyamide, particularly as a coacervate and complex coacervate. For the purposes of the present invention, gelatin-containing complex coacervates are understood to mean a combination of gelatin with a synthetic polyelectrolyte. Suitable synthetic polyelectrolytes are, for example, copolymers incorporating maleic acid, acrylic acid, methacrylic acid, acrylamide, and methacrylamide units. It is particularly preferred to use acrylic acid and acrylamide. Gelatin-containing capsules can be hardened using conventional hardeners, such as formaldehyde or glutaric dialdehyde. The encapsulation of monomer microdroplets using gelatin, gelatin-containing coacervates, and gelatin-containing complex coacervates is described in detail in EP-A-0 046 535. Methods of encapsulation using synthetic polymers are known. Interfacial condensation is preferred, in which a reactive component (especially an isocyanate or an acid chloride) dissolved in monomer microdroplets is reacted with a second reactive component (especially an amine) dissolved in an aqueous phase.

[0059] The heterodisperse or optionally microencapsulated monodisperse monomer microdroplets preferably contain at least one initiator or a mixture of initiators (combination of initiators) that initiates polymerization.The initiator suitable for the process according to the present invention is a peroxy compound, particularly preferably dibenzoyl peroxide, dilauroyl peroxide, bis(p-chlorobenzoyl) peroxide, dicyclohexyl peroxydicarbonate, tert-butyl peroctoate, tert-butyl peroxy-2-ethylhexanoate, 2,5-bis(2-ethylhexanoylperoxy)-2,5-dimethylhexane, or tert-amyl peroxy-2-ethylhexane, and an azo compound, such as 2,2'-azobis(isobutyronitrile) or 2,2'-azobis(2-methylisobutyronitrile).It is particularly preferred to use dibenzoyl peroxide as initiator. If a polymerization inhibitor is used, it is very particularly preferable to use tert-butyl peroxy-2-ethylhexanoate as initiator.

[0060] The initiator is preferably used in an amount of 0.05% to 2.5% by weight, particularly preferably 0.1% to 1.5% by weight, based on the monomer mixture.

[0061] The optionally monodisperse microencapsulated monomer microdroplets may also optionally contain up to 30% by weight (based on monomer) of a crosslinked or non-crosslinked polymer. Preferred polymers are those derived from the above-mentioned monomers, particularly preferably styrene.

[0062] In the preparation of monodisperse or heterodisperse polymers in the process according to the present invention, the aqueous phase may further contain a dissolved polymerization inhibitor in a preferred embodiment. Useful inhibitors in this case include both inorganic and organic substances. Preferred inorganic inhibitors include salts of transition metals, such as copper(II) chloride, copper(II) sulfate, iron(III) chloride, iron(II) sulfate, and manganese(II) chloride, as well as inorganic nitrogen compounds, particularly hydroxylamine, hydrazine, sodium nitrite, and potassium nitrite, salts of phosphorous acid, such as sodium hydrogen phosphite, and also sulfur-containing compounds, such as sodium dithionite, sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium thiocyanate, and ammonium thiocyanate. Examples of organic inhibitors are phenolic compounds, such as hydroquinone, hydroquinone monomethyl ether, resorcinol, catechol, tert-butylcatechol, pyrogallol, and condensation products of phenols with aldehydes. Further suitable organic inhibitors are organic nitrogen-containing compounds. Particularly preferred are hydroxylamine derivatives, such as N,N-diethylhydroxylamine, N-isopropylhydroxylamine, and sulfonated or carboxylated N-alkylhydroxylamines or N,N-dialkylhydroxylamine derivatives, hydrazine derivatives, such as N,N-hydrazinodiacetic acid, and nitroso compounds, such as preferably N-nitrosophenylhydroxylamine, N-nitrosophenylhydroxylamine ammonium salt, or N-nitrosophenylhydroxylamine aluminum salt. The concentration of the inhibitor (based on the aqueous phase) is preferably 5 to 1000 ppm, particularly preferably 10 to 500 ppm, and very particularly preferably 10 to 250 ppm.

[0063] Preferably, at least one polymerization inhibitor is used in the process according to the invention. Sodium nitrite or resorcinol are particularly preferred as inhibitors.

[0064] In addition to the dispersant mixture used in the process according to the present invention, further dispersants may be added. Suitable additional dispersants are natural or synthetic water-soluble polymers, preferably gelatin, starch, polyvinyl alcohol, polyvinylpyrrolidone, polyacrylic acid, polymethacrylic acid, or copolymers of (meth)acrylic acid and (meth)acrylic acid esters. Gelatin is particularly preferred. The amount of additional dispersant used is generally 0.05% to 10% by weight, preferably 0.05% to 5% by weight, based on the dispersant mixture of a) and b) used in the present invention. It is preferred not to add further dispersants in addition to the dispersant mixture used in the process according to the present invention.

[0065] In an alternative preferred embodiment, the polymerization to obtain heterodisperse or monodisperse polymers can be carried out in the presence of a buffer system. A buffer system capable of adjusting the pH of the aqueous phase to a value between 14 and 6, preferably between 12 and 8, before the start of the polymerization is preferred. Under these conditions, dispersants containing carboxylic acid groups are present wholly or partially as salts, which has a favorable effect on the dispersant's function. Particularly suitable buffer systems contain salts of phosphoric or boric acid. For the purposes of the present invention, "phosphate" and "borate" also encompass the ortho-condensates of the corresponding acids and salts. The concentration of phosphate in the aqueous phase is preferably 0.5 to 500 mmol / L, particularly preferably 2.5 to 100 mmol / L.

[0066] The agitation speed in polymerization to obtain monodisperse polymers is not very important and does not affect the particle size, in contrast to conventional polymerization. A low agitator speed is used that is sufficient to keep the suspended monomer droplets in suspension and promote the removal of the heat of polymerization. For this purpose, various agitator types can be used. A particularly suitable agitator is a shaft-acting gate agitator.

[0067] The volume ratio of the monomer microdroplets to the aqueous phase is preferably 1:0.75 to 1:20, particularly preferably 1:1 to 1:6. It is irrelevant whether heterodisperse or monodisperse polymers are prepared.

[0068] The polymerization temperature for obtaining heterodisperse or monodisperse polymers is determined by the decomposition temperature of the initiator used. It is preferably 50 to 180°C, particularly preferably 55 to 130°C. The polymerization is preferably continued for 0.5 to approximately 20 hours. It has been found useful to initiate the polymerization at a low temperature, preferably 60°C, and use a temperature program in which the reaction temperature is increased as the polymerization conversion progresses. In this way, it is possible to achieve requirements such as reliable reaction progress and high polymerization conversion rates very effectively. After the polymerization reaction, the polymer can be isolated by a conventional method, such as filtration or decantation, and optionally washed.

[0069] The preparation of monodisperse polymers using the jet or seed-feed method is known in the prior art and is described, for example, in US Pat. No. 4,444,961, EP-A0 046 535, US Pat. No. 4,419,245 or WO 93 / 12167.

[0070] Preferably, monodisperse polymers are prepared using the jet method or the seed-feed method.

[0071] Preferably, macroporous heterodisperse polymers are prepared by the process according to the present invention.

[0072] Macroporous polymers are preferably used to prepare ion exchangers, which can be functionalized by known methods, such as sulfonation, chloromethylation, or phthalamidation, and reacted with alkylamines to give cation or anion exchangers and chelating resins.

[0073] The present invention therefore also relates to a method for preparing macroporous polymers, a) at least one hydroxyalkyl methylcellulose having a molecular weight of 80,000 g / mol to 110,000 g / mol; b) at least one hydroxyalkyl methylcellulose having a molecular weight of 25,000 g / mol to 42,000 g / mol; The present invention also includes the use of a dispersant mixture comprising:

[0074] The invention further relates to the use of macroporous polymers prepared using the dispersant mixture for the manufacture of ion exchangers.

[0075] <Method> [Measurement of polymer fine particle fraction] To measure the polymer fine particle fraction, the reaction mixture containing the polymer and aqueous phase was sieved through a 100 μm mesh sieve. The filtrate was then passed through a 20 μm sieve. This allowed the polymer fine particle fraction to be fractionated and weighed as the target particle size fraction of 20 to 100 μm. Any fine particle fraction and the aqueous phase remaining after sieving through the 20 μm sieve were evaporated and dried to a constant weight. The polymer fine particle fraction was then weighed and calculated as a percentage based on the polymer yield. [Example]

[0076] Example 1 (according to the present invention) A glass reactor was initially charged with deionized water (869 mL) and 96.6 g of a 2 wt % aqueous solution of a) 2-hydroxypropylmethylcellulose (HPMC), CAS: 9004-65-3, average viscosity, 2% in water at 20°C: 4550 mPas, 28.5 mol % methoxyl, 5.75 mol % hydroxypropyl, number average molecular weight: 95,000 g / mol (Type A), and b) 2-hydroxypropylmethylcellulose (HPMC), CAS: 9004-65-3, average viscosity, 2% in water at 20°C: 100 mPas, 21.5 mol % methoxyl, 9.5 mol % hydroxypropyl, number average molecular weight: 33,500 g / mol (Type B) (1:1 weight ratio). Disodium hydrogen phosphate decahydrate (4.69 g, 0.48 wt % based on the aqueous phase) was further dissolved in the solution. The pH of the aqueous phase is then adjusted to 11 by adding NaOH (1 M, 8-12 mL). A mixture of styrene (540.3 g, 80.4 wt%), divinylbenzene (5.5 wt%, 59.7 g), isododecane (351.5 g, 32 wt%), and dibenzoyl peroxide (BPO) (4.69 g, 0.43 wt%) (based on the organic phase) is added to the aqueous phase. A stream of nitrogen is introduced into the vessel at 20 L / h. The mixture is heated to 73°C at 190 rpm for 1 hour, then held at this temperature for 7 hours, then heated to a maximum of 95°C over 1 hour, held at this temperature for 2 hours, and then cooled to room temperature. In this example, 559 g of polymer and 3.9 g of fine particle fraction were isolated.

[0077] Example 2 (according to the present invention) Example 1 was repeated, but using 3.23 g of tert-butylperoxy-2-ethylhexanoate (T21s) instead of the initiator benzoyl peroxide (BPO). In this example, 582 g of polymer and 5.7 g of fine particle fraction were isolated.

[0078] Example 3 (according to the present invention) Example 1 was repeated, but 3.23 g of tert-butylperoxy-2-ethylhexanoate (T21s) was used instead of the initiator benzoyl peroxide (BPO). In addition, resorcinol (c=0.08 g / L in aqueous phase) was added to the aqueous phase. In this example, 587 g of polymer and 3.1 g of fine particle fraction were isolated.

[0079] Example 4 (not according to the invention, without the low molecular weight dispersant component b)) First, a glass reactor was charged with deionized water (869 mL) and 96.6 g of a 2 wt. % aqueous solution of 2-hydroxypropylmethylcellulose (HPMC), CAS: 9004-65-3, average viscosity, 2% in water at 20°C: 4550 mPas, 28.5 mol. % methoxyl, 5.75 mol. % hydroxypropyl, number average molecular weight: 95,000 g / mol (Type A). Disodium hydrogen phosphate decahydrate (4.69 g, 0.48 wt. % based on the aqueous phase) was further dissolved in the solution. The pH of the aqueous phase was then adjusted to 11 by adding 1 M NaOH (8-12 mL). To the aqueous phase is added a mixture of styrene (540.3 g, 80.4 wt%), divinylbenzene (5.5 wt%, 59.7 g), isododecane (351.5 g, 32 wt%), and dibenzoyl peroxide (BPO) (4.69 g, 0.43 wt%) (based on the organic phase). A stream of nitrogen is introduced into the vessel at 20 L / h. The mixture is heated initially to 73°C at 190 rpm for 1 hour, then held at this temperature for 7 hours, then heated up to 95°C over 1 hour, held at this temperature again for 2 hours, and then cooled to room temperature. In this example, 569 g of polymer and 6.9 g of fine particle fraction were isolated.

[0080] Example 5 (not according to the invention, without the low molecular weight dispersant component b) and with the initiator of Example 2 of EP-A-0964002) Example 4 was repeated, but using 3.23 g of tert-butylperoxy-2-ethylhexanoate (T21s) instead of the initiator benzoyl peroxide (BPO). In this example, 522 g of polymer and 10.2 g of fine particle fraction were isolated.

[0081] Example 6 (not according to the invention, without the use of high molecular weight dispersant component a)) Example 4 was repeated, but using the same weight of the following instead of Type A: 2-hydroxypropylmethylcellulose (HPMC), CAS: 9004-65-3, average viscosity, 2% in water @ 20°C: 100 mPas, methoxyl: 21.5 mol%, hydroxypropyl: 9.5 mol%, number average molecular weight: 33,500 g / mol (Type B) (weight ratio of Type A to Type B: 1:1). In this example, 574 g of polymer and 7.8 g of fine particle fraction were isolated.

[0082] Example 7 (not according to the invention, without the high molecular weight dispersant component a) and with the initiator of Example 2 of EP-A-0964002) Example 4 was repeated, but Type A was replaced with the same weight of the following: 2-hydroxypropylmethylcellulose (HPMC), CAS: 9004-65-3, average viscosity, 2% in water at 20°C: 100 mPas, methoxyl: 21.5 mol%, hydroxypropyl: 9.5 mol%, number average molecular weight: 33,500 g / mol (Type B). In addition, the initiator BPO was replaced with 3.23 g of tert-butyl peroxy-2-ethylhexanoate (T21s). In this example, 570 g of polymer and 9.8 g of fine particle fraction were isolated.

[0083] Example 8 (not according to the invention, but comparative example 1 of EP-A-0964002, using resorcinol instead of sodium nitrite as inhibitor) First, a glass reactor was charged with deionized water (869 mL) and 96.6 g of a 2 wt% aqueous solution of methylcellulose (average viscosity 4000 mPas, Sigma Aldrich). Disodium hydrogen phosphate decahydrate (4.69 g, 0.48 wt% based on the aqueous phase) and resorcinol (c = 0.08 g / L in the aqueous phase) were further dissolved in this solution. The pH of the aqueous phase was then adjusted to 11 by adding NaOH (1 M, 8-12 mL). A mixture of styrene (540.3 g, 80.4 wt%), divinylbenzene (5.5 wt%, 59.7 g), isododecane (351.5 g, 32 wt%), and dibenzoyl peroxide (BPO) (4.69 g, 0.43 wt%) (based on the organic phase) was added to the aqueous phase. A nitrogen stream was introduced into the vessel at 20 L / h. The mixture is heated initially to 73°C at 190 rpm for 1 hour, then held at this temperature for 7 hours, then heated up to 95°C over 1 hour, held at this temperature again for 2 hours, and then cooled to room temperature. In this example, 569 g of polymer and 7.2 g of fine particle fraction were isolated.

[0084] Example 9 (according to the present invention) Example 1 was repeated, but instead of a mixture of Type A and Type B, the same weight of a mixture of hydroxyethyl methylcellulose (methoxy substitution: 28.5 mol%, hydroxyethoxy substitution: 10 mol%, number average molecular weight: 95,000 g / mol) and 2-hydroxypropyl methylcellulose (HPMC) (CAS: 9004-65-3, average viscosity, 2% in water at 20°C: 100 mPas, methoxyl: 21.5 mol%, hydroxypropyl: 9.5 mol%, number average molecular weight: 33,500 g / mol (Type B)) was used as the dispersant (1:1 weight ratio). Additional resorcinol (0.08 g / L) was added to the reaction mixture. In this example, 582 g of bead polymer and 5.7 g of fine particle fraction were isolated.

[0085] [Table 1]

[0086] Examples 1 to 3 and 9 according to the present invention show that by using a dispersant mixture containing a particular hydroxyalkylmethylcellulose, the polymer fines fraction can be surprisingly reduced in polymer preparations.

Claims

1. A method for producing a polymer, comprising: reacting at least one aromatic monoethylenically unsaturated compound and at least one aromatic multiethylenically unsaturated compound in the presence of at least one initiator, in the presence of water, in the presence of a porogen, and a) at least one hydroxyalkyl methylcellulose having a number average molecular weight of 80,000 g / mol to 110,000 g / mol and mixtures of these compounds, and b) at least one hydroxyalkylmethylcellulose having a number average molecular weight of 25,000 g / mol to 42,000 g / mol and mixtures of these compounds reacting in the presence of a dispersant mixture comprising:

2. 2. The method for producing a polymer according to claim 1, characterized in that the hydroxyalkyl methylcellulose in a) and b) is selected from the group of 2-hydroxypropyl methylcellulose or hydroxyethyl methylcellulose and mixtures of these compounds.

3. 3. The method for producing a polymer according to claim 1, wherein the initiator used is dibenzoyl peroxide, dilauroyl peroxide, bis(p-chlorobenzoyl)peroxide, dicyclohexylperoxydicarbonate, tert-butylperoctoate, tert-butylperoxy-2-ethylhexanoate, 2,5-bis(2-ethylhexanoylperoxy)-2,5-dimethylhexane or tert-amylperoxy-2-ethylhexane, 2,2'-azobis(isobutyronitrile) or 2,2'-azobis(2-methylisobutyronitrile), or a mixture of these initiators.

4. 3. The process for producing a polymer according to claim 1 or 2, characterized in that the aromatic monoethylenically unsaturated compound used is styrene, vinyltoluene, ethylstyrene, α-methylstyrene, chlorostyrene or chloromethylstyrene, or a mixture of these compounds.

5. 3. The process for producing polymers according to claim 1 or 2, characterized in that the aromatic polyethylenically unsaturated compound used is divinylbenzene, divinyltoluene, trivinylbenzene, divinylnaphthalene or trivinylnaphthalene, or a mixture of these compounds.

6. 3. A process for producing a polymer according to claim 1, characterized in that the monoethylenically unsaturated compound used is styrene and the polyethylenically unsaturated compound used is divinylbenzene.

7. 3. A process for producing a polymer according to claim 1, characterized in that the pH of the aqueous phase before polymerization is adjusted to a value between 12 and 8.

8. 3. The process for producing a polymer according to claim 1 or 2, characterized in that the component a) used is 2-hydroxypropyl methylcellulose having a degree of 2-hydroxypropyl substitution of 3 to 15 mol % and a degree of methoxy substitution of 26 to 31 mol %.

9. 3. The process for producing a polymer according to claim 1 or 2, characterized in that the component b) used is 2-hydroxypropylmethylcellulose having a degree of hydroxypropyl substitution of 3 to 15 mol % and a degree of methoxy substitution of 18 to 25 mol %.

10. 3. The method for producing a polymer according to claim 1, wherein the weight ratio of the hydroxyalkyl methylcellulose a) and b) is from 3:1 to 1:

1.

11. 3. The method for producing a polymer according to claim 1, wherein the total combined concentration of the hydroxyalkyl methylcelluloses a) and b) is 0.15 to 0.3% by weight, based on the aqueous phase.

12. 3. A process for producing a polymer according to claim 1 or 2, characterized in that an inhibitor is used, which is in particular selected from the group of sodium dithionite, sodium thiosulfate, sodium sulfite, sodium bisulfite, sodium thiocyanate, ammonium thiocyanate, hydroquinone, hydroquinone monomethyl ether, resorcinol, catechol, tert-butylcatechol or pyrogallol.

13. 3. A process for producing a polymer according to claim 1 or 2, characterized in that a porogen is used, which is in particular selected from the group of hexane, octane, isooctane, isododecane, methyl ethyl ketone, methyl isobutyl ketone, methyl isobutyl carbinol or octanol.

14. 3. A process for producing a polymer according to claim 1 or 2, characterized in that the polymerization is carried out at a temperature of from 55 to 130°C.

15. For producing macroporous aromatic copolymers, a) at least one hydroxyalkyl methylcellulose having a number average molecular weight of 80,000 g / mol to 110,000 g / mol, and b) at least one hydroxyalkyl methylcellulose having a number average molecular weight of 25,000 g / mol to 42,000 g / mol; Use of a dispersant mixture comprising:

16. 16. Use according to claim 15, wherein the preparation of macroporous aromatic copolymers relates to polystyrene-divinylbenzene copolymers.

17. 17. The use according to claim 15 or 16, wherein the copolymer is used as a base material for producing an ion exchanger.

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