EP1789455A1

EP1789455A1 - Method for producing polymers by dispersion polymerisation

Info

Publication number: EP1789455A1
Application number: EP05782587A
Authority: EP
Inventors: Dennis LÖSCH; Volker Seidl; Pulakesh Mukherjee; Hans-Ulrich Moritz
Original assignee: BASF SE
Current assignee: BASF SE
Priority date: 2004-09-02
Filing date: 2005-08-09
Publication date: 2007-05-30
Also published as: JP2008511699A; DE102004042946A1; US20080045624A1; CN101010346A; WO2006024370A1

Abstract

The invention relates to a method for producing polymers by dispersion polymerisation. According to said method, the aqueous monomer solution contains at least one displacer, enabling the polymer to separate from the aqueous solution during the polymerisation process. The invention also relates to water-soluble or water-swellable compounds and to the use of the latter for thickening and/or absorbing liquids.

Description

Process for the preparation of polymers by spray polymerization

description

The present invention relates to a process for the preparation of polymers by spray polymerization, moreover water-soluble or water-swellable compositions and their use for thickening and / or absorption of liquids.

Further embodiments of the present invention can be found in the claims, the description and the examples. It is understood that the features of the subject matter according to the invention mentioned above and those yet to be explained below can be used not only in the respectively indicated combination but also in other combinations without departing from the scope of the invention.

US-A-4,380,600, EP-A-0 183 466 and WO-A-97/34933 describe processes for preparing aqueous dispersions of high solids water-soluble polymers. The polymer dispersions have a significantly lower viscosity than polymer solutions having a comparable solids content.

EP-A-0 398 151 describes the two-stage preparation of polymeric thickeners. In a first stage, an aqueous polymer solution or dispersion is prepared by polymerization, which is spray dried in a second stage.

GB-A-0 777 306 describes the preparation of polymers by spray polymerization. The reaction is catalyzed by amides such as acrylamide, acetamide and partially hydrolyzed polyacrylonitrile. In the examples, 0.7 to 1.1% by weight, based on the monomer solution, of a polymerization catalyst were used. The polymers can also be used as thickeners for synthetic resin dispersions.

The object of the present invention was to provide an improved process for the preparation of polymers and water-soluble or water-swellable compositions which dissolve rapidly in aqueous liquids or swell rapidly.

The object was achieved by a method for spray polymerization, wherein a monomer solution containing

a) at least one water-soluble ethylenically unsaturated monomer, b) at least one initiator and c) water, is sprayed into a reaction space and polymerized, characterized in that the monomer solution additionally contains at least one displacer d), wherein the displacer

d1) from 5 to 50% by weight of at least one water-soluble polymer, d2) from 1 to 40% by weight of at least one water-soluble salt,

in each case based on the monomer solution, or a mixture of displacers d1) and d2).

A displacer is a substance or a mixture of different substances which is readily soluble in water and which reduces the solubility of the polymer obtainable by the novel process in the aqueous solution.

The solubility of the displacer is typically at least 1 g / 100 g of water, preferably at least 5 g / 100 g of water, more preferably at least 25 g / 100 g of water, most preferably at least 50 g / 100 g of water.

For example, the monomer solution containing the displacer may be homogeneous. The resulting polymer is then insoluble, precipitates disperse during the polymerization and grows in disperse phase on.

But it is also possible that already the monomers are forced by the displacer from the aqueous phase and the polymerization starts already in disperse phase. If in this case the displacer is added just before the reactor, it is possible to dispense with additives which stabilize the monomer dispersion.

Preferred displacers reduce the solubility of the polymer at least so that the polymer forms a disperse phase in the monomer solution at a monomer conversion of up to 90 mol%, preferably up to 50 mol%, particularly preferably up to 30 mol%.

As displacer, for example, one or a mixture of two or more different water-soluble polymers d1) can be used. Furthermore, one or a mixture of two or more different water-soluble salts d2) are suitable as displacers. Furthermore, it is also possible to use mixtures of water-soluble polymers d1) and water-soluble salts d2) as displacers.

Water-soluble polymers d1) are, for example, graft polymers of vinyl acetate and / or vinyl propionate on polyethylene glycols, on one or both sides with alkyl, carboxyl or amino groups end-capped polyethylene glycols, copolymers of te from Alkylpolyalkylenglykolacrylaten or Alkylpolyalkylenglykolmethacrylaten and acrylic acid and / or methacrylic acid, polyalkylene glycols, one or both sides with alkyl, carboxyl or amino groups endgruppenverschlossene polyalkylene glycols, hydrolyzed copolymers of vinyl alkyl ethers and maleic anhydride in the form of free carboxyl groups and in the form of at least partially with alkali metal hydroxides or ammonium bases neutralized salts and / or a water-soluble starch from the group of cationically modified potato starch, anionically modified potato starch, degraded potato starch and maltodextrin, polyvinylpyrrolidones, polyacrylic acids and polymethacrylic acids in the form of the free carboxyl groups and in the form of at least partially neutralized with alkali metal hydroxides or ammonium bases salts, or a mixture of two or more of the aforementioned water-soluble polymers. Very particular preference is given to polyvinylpyrrolidone, polyethylene glycol, polyvinylamine and / or polyacrylic acid.

The average molecular weight of the water-soluble polymers is up to 250,000 g / mol, preferably up to 100,000 g / mol, particularly preferably up to 50,000 g / mol. Higher molecular weights increase the viscosity of the monomer solution and thus complicate the spraying / dripping into the reaction space.

In principle, it is also possible to use water-soluble polymers d1) based on the monomers a). Such a case is, for example, when the monomer to be used in addition to acrylic acid as the monomer a) also contains polyacrylic acid as a displacer.

The concentration of the water-soluble polymer d1) in the monomer solution is usually 5 to 50% by weight, preferably 8 to 30% by weight, particularly preferably 10 to 20% by weight.

The water-soluble salts d2) used are preferably inorganic salts, for example sodium sulfate, sodium chloride, potassium sulfate, potassium chloride, or a mixture of two or more of the abovementioned salts. Very particular preference is given to sodium sulfate.

The concentration of the water-soluble salt d2) in the monomer solution is usually from 1 to 40% by weight, preferably from 2 to 30% by weight, particularly preferably from 5 to 20% by weight.

In a preferred embodiment, at least one complexing agent is additionally added to the monomer solution, preferably ethylenediaminetetraacetic acid. Thus, for example, iron ions dissolved out of pipelines are complexed and a possible interaction of the iron ions with the polymerization is minimized. This is particularly important because transition metal ions as catalysts in Graft polymerizations are used. However, a graft polymerization with the polymers d1) used as encapsulants as graft base is undesirable in the process according to the invention.

The concentration of the complexing agent in the monomer solution is usually 0.0001 to 0.1 wt .-%, preferably 0.0005 to 0.05 wt .-%, particularly preferably 0.001 to 0.01 wt .-%.

The viscosity of the monomer solution can be measured according to DIN 51562 and is at 23 ° C up to 100 mPas, preferably up to 50 mPas, more preferably up to 25 mPas, most preferably up to 10 mPas.

The reaction can be carried out in the presence of an inert carrier gas, where inert means that the carrier gas can not react with the constituents of the monomer solution. Of course, it is also possible to use a mixture of different complexing agents. The inert carrier gas is preferably nitrogen. The oxygen content of the inert carrier gas is advantageously less than 1% by volume, preferably less than 0.5% by volume, more preferably less than 0.1% by volume.

The inert carrier gas can be passed through the reaction space in cocurrent or in countercurrent to the freely falling drops of the monomer solution, preferably in cocurrent.

The gas velocity is preferably adjusted so that the flow is directed in the reactor, for example, there are no convection vortices opposite the general flow direction, and is for example 0.02 to 1.5 m / s, preferably 0.05 to 0.4 m / s.

The reaction temperature is usually between 70 to 250 ^° C., preferably 80 to 190 ^° C., particularly preferably 90 to 140 ^° C.

The concentration of the monomers a) in the monomer solution is usually from 2 to 50% by weight, preferably from 5 to 40% by weight, particularly preferably from 10 to 30% by weight.

The solubility of the monomers a) in water is typically at least 1 g / 100 g of water, preferably at least 5 g / 100 g of water, more preferably at least 25 g / 100 g of water, most preferably at least 50 g / 100 g of water.

Ethylenically unsaturated monomers a) are, for example, ethylenically unsaturated C ₃ -C ₆ -carboxylic acids. These compounds are, for example, acrylic acid, methacrylic acid, ethacrylic acid, α-chloroacrylic acid, crotonic acid, maleic acid, maleic anhydride, itaconic acid, citraconic acid, mesaconic acid, glutaconic acid, A conic acid and fumaric acid and the alkali metal or ammonium salts of these acids.

Further monomers a) are acrylamidopropanesulfonic acid, vinylphosphonic acid and / or alkali metal or ammonium salts of vinylsulfonic acid, with acids being used either in unneutralized form or in partially or up to 100% neutralized form.

Also suitable are monoethylenically unsaturated sulfonic or phosphonic acids as monomers a), for example allylsulfonic acid, sulfoethyl acrylate, sulfopropyl methacrylate, sulfopropyl acrylate, sulfopropyl methacrylate, 2-hydroxy-3-acryloxypropylsulfonic acid, 2-hydroxy-3-methacryloxypropylsulfonic acid, allylphosphonic acid, styrenesulfonic acid and 2-acrylamido-2-methyl propane sulfonic acid.

Further monomers a) are, for example, acrylamide, methacrylamide, crotonic acid amide, acrylonitrile, methacrylonitrile, dimethylaminoethyl methacrylate, dimethylaminoethyl acrylate, dimethylaminopropyl acrylate, diethylaminopropyl acrylate, dimethylaminobutyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl methacrylate, dimethylaminoneopentyl acrylate and dimethylaminoneopentyl methacrylate and their quaternization products, for example with methyl chloride , Hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxypropyl acrylate and hydroxypropyl methacrylate.

Further monomers a) are monomers obtainable by reaction of nitrogen-containing heterocycles and / or carboxamides, such as vinylimidazole, vinylpyrazole and vinylpyrrolidone, vinylcaprolactam and vinylformamide, with acetylene, which may also be quaternized, for example with methyl chloride, and monomers , which are obtainable by reaction of nitrogen-containing compounds, such as diallyldimethylammonium chloride, with allyl alcohol or allyl chloride.

Furthermore, vinyl and allyl esters and also vinyl and allyl ethers, such as vinyl acetate, allyl acetate, methyl vinyl ether and methyl allyl ether, can also be used as monomers a).

The monomers a) can be used alone or mixed with one another, for example mixtures comprising two or more monomers a). It is preferred to use mixtures with two different monomers a).

Preferred monomers a) are acrylic acid, methacrylic acid and the alkali metal or ammonium salts of these acids, acrylamide, methacrylamide, acrylonitrile, methacrylonitrile, itaconic acid, vinylformamide, vinylpyrrolidone, vinylimidazole, quaternized vinylimidazole, vinyl acetate, sodium vinylsulfonate, vinylphosphonic acid, hydroxyethyl acrylate, hydroxyethyl methyl methacrylate, 2-acrylamido-2-methylpropanesulfonic acid, diallyldimethylammonium chloride and mixtures thereof.

The monomers a) are preferably stabilized with a commercially available polymerization inhibitor, particularly preferably with a polymerization inhibitor which acts only together with oxygen, for example hydroquinone monomethyl ether.

Commercially available polymerization inhibitors are polymerization inhibitors which, for reasons of product safety, are used as storage stabilizers in the respective monomers. Examples of such storage stabilizers are hydroquinone, hydroquinone monomethyl ether, 2,5-di-tert-butylhydroquinone and 2,6-di-tert-butyl-4-methylphenol.

The preferred polymerization inhibitors require dissolved oxygen for optimum performance. Thus, prior to polymerization, the polymerization inhibitors may be prepared by inerting, i. Flow through with an inert gas, preferably nitrogen, to be freed of dissolved oxygen. The oxygen content of the monomer solution before the polymerization is preferably reduced to less than 1 ppm by weight, more preferably less than 0.5 ppm by weight.

The monomers a) are polymerized in aqueous solution in the presence of initiators b) mitein¬ other.

The initiators b) are used in customary amounts, for example in amounts of from 0.001 to 5% by weight, preferably from 0.01 to 1% by weight, based on the monomers to be polymerized.

As initiators b) it is possible to use all compounds which decompose into free radicals under the polymerization conditions, for example peroxides, hydroperoxides, hydrogen peroxide, persulfates, azo compounds and the so-called redox initiators. Preference is given to the use of water-soluble initiators. In some cases it is advantageous to use mixtures of different initiators, for example mixtures of hydrogen peroxide and sodium or potassium peroxodisulfate. Mixtures of hydrogen peroxide and sodium peroxodisulfate can be used in any ratio.

Suitable organic peroxides are, for example, acetylacetone peroxide, methyl ethyl ketone peroxide, tert-butyl hydroperoxide, cumene hydroperoxide, tert-amyl perpivalate, tert-butyl perpivalate, tert-butyl pheohexanoate, tert-butyl perisobutyrate, tert-butyl per-2-ethylhexanoate, tert. Butyl perisononanoate, tert-butyl permaleate, tert-butyl perbenzoate, di- (2-ethylhexyl) peroxydicarbonate, dicyclohexyl peroxydicarbonate, di- (4-tert-butylcyclohexyl) peroxydicarbonate, dimyristil peroxydicarbonate, diacetyl peroxydicarbonate, allylpe- rester, cumyl peroxyneodecanoate, tert-butyl per 3,5,5-trimethylhexanoate, acetylcyclohexylsulfonyl peroxide, dilauryl peroxide, dibenzoyl peroxide and tert-amyl pemeodecanoate.

Preferred initiators b) are azo compounds, for example 2,2'-azobis-isobutyronitrile, 2,2'-azobis (2,4-dimethylva-nitronitrile) and 2,2'-azobis (4-methoxy-2,4-dimethyl) valeronitrile), in particular water-soluble azo initiators, for example 2,2'-azobis {2- [1- (2-hydroxyethyl) -2-imidazolin-2-yl] propane} dihydrochloride, 2,2'-azobis (2-amidino) propane) dihydrochloride, 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride and 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride. Very particular preference is given to 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride and 2,2'-azobis [2- (5-methyl-2-imidazolin-2-yl) propane] dihydrochloride.

Further preferred initiators b) are also redox initiators. The redox initiators contain as oxidizing component at least one of the abovementioned peroxo compounds and as reducing component, for example, ascorbic acid, glucose, sorbose, ammonium or alkali metal hydrogen sulfite, sulfite, thiosulfate, hyposulfite, pyrosulfite, sulfide or sodium hydroxymethyl sulfoxylate. As reducing component of the redox catalyst it is preferable to use ascorbic acid or sodium pyrosulfite. Based on the nomeren used in the polymerization amount of Mo is used, for example, 1 x ^{10 -5} to 1 mol% of the reducing component of the redox catalyst there are suitable.

The polymerization is particularly preferably initiated by the action of high-energy radiation, it usually being known as photoinitiators as initiator b). These may be, for example, so-called α-splitters, H-abstracting systems or also azides. Examples of such initiators are benzophenone derivatives such as Michler's ketone, phenanthrene derivatives, fluorene derivatives, anthraquinone derivatives, thioxanthone derivatives, coumarin derivatives, benzoin ethers and their derivatives, azo compounds, such as the abovementioned radical formers, substituted hexaaryl-bis-midazoles or acylphosphine oxides, especially 2-hydroxy-2-methylpropiophenone (Darocure® 1173). Examples of azides are 2- (N, N-dimethylamino) ethyl-4-azidocinnamate, 2- (N, N-dimethylamino) ethyl-4-azidonaphthyl ketone, 2- (N, N-dimethylamino) - ethyl 4-azidobenzoate, 5-azido-1-naphthyl-2 '- (N, N-dimethylamino) ethylsulfone, N- (4-sulfonylazidophenyl) maleimide, N-acetyl-4-sulfonylazidoaniline, 4-sulfonylazido- aniline , 4-azidoaniline, 4-azidophenacyl bromide, p-azidobenzoic acid, 2,6-bis (p-azidobenzylidene) cyclohexanone and 2,6-bis (p-azido-benzylidene) -4-methylcyclohexanone.

Particularly preferred initiators b) are azo initiators, such as 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride and 2,2'-AΣobis [2- (5-methyl-2-imidazoIin -2-yl) propane] dihydrochloride, and photoinitiators such as 2-hydroxy-2-methylpropiophenone and 1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one , Redox initiator such as sodium persulfate / hydroxymethylsulfinic acid, ammonium peroxodisulfate / hydroxymethylsulfuric acid, hydrogen peroxide / hydroxymethylsulfinic acid, sodium persulfate / ascorbic acid, ammonium peroxodisulfate / ascorbic acid and hydrogen peroxide / ascorbic acid, photoinitiators such as 1- [4- (2-hydroxyethoxy) -phenyl] - 2-hydroxy-2-methyl-1-propan-1-one, and mixtures thereof.

As component c), the monomer solution contains water.

The pH of the monomer solution is not critical. However, according to the product requirements, the pH of the polymer according to the invention can be adjusted to the desired range via the pH of the monomer solution. For example, polymers for cosmetic applications should have a pH of around 7.

The polymerization of the monomers a) can be carried out in the presence of a crosslinker or a combination of different crosslinkers. Crosslinkers are compounds with at least two polymerizable groups. The polymerization in the presence of at least one crosslinker is preferred.

The concentration of the crosslinkers in the monomer solution is usually 0.001 to 1% by weight, preferably 0.01 to 0.5% by weight.

Suitable crosslinkers are, for example, (meth) acrylic acid esters of polyhydric alcohols which may be alkoxylated with up to 100, usually up to 50, ethylene oxide and / or propylene oxide units. Suitable polyhydric alcohols are in particular C ₂ -C _O alkane polyols having 2 to 6 hydroxyl groups, such as ethylene glycol, glycerol, trimethylolpropane, pentaerythritol or sorbitol. Preferred crosslinkers are polyethylene glycol diacrylate and polyethylene glycol dimethacrylates, each of which can be derived from polyethylene glycols (which can be considered to be ethoxylated ethylene glycol) having a molecular weight of from 200 to 2,000. Further suitable crosslinkers are methylenebisacrylamide, trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, ethylene glycol diacrylate, propylene glycol diacrylate, butanediol diacrylate, hexanediol diacrylate, hexanediol dimethacrylate or diacrylates and dimethacrylates of block copolymers of ethylene oxide and propylene oxide.

Further suitable crosslinkers are diallyl carbonate, allyl carbonates or allyl ethers of polyhydric alcohols which may be alkoxylated with up to 100, usually up to 50, ethylene oxide and / or propylene oxide units, and allyl esters of polybasic carboxylic acids.

Allyl carbonates of polyhydric alcohols correspond to the general formula I.

wherein A is the radical of a polyhydric alcohol which may be alkoxylated with 0 to 100, usually 0 to 50, ethylene oxide and / or propylene oxide units; and n is the valence of the alcohol, for example an integer from 2 to 10, preferably 2 to 5. A particularly preferred example of such a compound is ethylene glycol di (allyl carbonate). Also suitable are especially polyethylene glycol di (allyl carbonates), which are derived from polyethylene glycols having a molecular weight of from 200 to 2,000.

As preferred examples of allyl ether. can be listed: polyethylene glycol diallyl derived from polyethylene glycols having a molecular weight of 200 to 2000; Pentraerythritol triallyl ether or trimethylolpropane diallyl ether. Also suitable are reaction products of ethylene glycol diglycidyl ether or polyethylene glycol glycidyl ether with 2 mol of allyl alcohol and / or pentaerythritol triallyl ether.

A suitable allyl ester of a polybasic carboxylic acid is dialyl phthalate, for example.

Preferred monomers a) or combinations of monomers a) are acrylamide / quaternized vinylimidazole, acrylamide / diallyldimethylammonium chloride, acrylamide / quaternized dimethylaminoethyl acrylate, vinylpyrrolidone / quaternized vinylimidazo), vinylpyrrolidone / diallyldimethylammonium chloride, vinylpyrrolidone / quaternized dimethylaminoethyl acrylate and acrylic acid.

Preferred initiators b) or combinations of initiators b) are azo initiators and azo initiators / photoinitiators.

Preferred displacers d) or combinations of displacers d) are polyvinylpyrrolidone / polyethylene glycol, sodium sulfate / polyvinylamine, polyethylene glycol / acrylic acid-maleic acid copolymers and acrylic acid-maleic acid copolymers,

The reaction is preferably carried out in apparatuses which are also suitable for spray drying. Such reactors are described, for example, in K. Masters, Spray Drying Handbook, 5th Edition, Longman, 1991, pages 23-66.

In the process according to the invention, one or more spray nozzles can be used. The applicable spray nozzles are subject to no restriction. Derarti- The nozzles to be sprayed liquid can be supplied under pressure. The division of the liquid to be sprayed can take place in that it is tensioned after reaching a certain minimum speed in the nozzle bore. Furthermore, it is also possible to use single-substance nozzles, such as slot nozzles or twist chambers (full cone nozzles) for the purpose according to the invention (for example from Düsen-Schlick GmbH, DE ₁ or Spraying Systems Deutschland GmbH, DE).

Full cone nozzles are preferred according to the invention. Of these, those with an opening angle of the spray cone of 60 to 180 ° are preferred. Opening angles of 90 to 120 ° are particularly preferred. The average droplet diameter which occurs during spraying is typically less than 1000 .mu.m, preferably less than 200 .mu.m, preferably less than 100 .mu.m, and usually greater than 10 .mu.m, preferably greater than 20 .mu.m, preferably greater than 50 .mu.m, and can be prepared by customary methods, such as light scattering, or be¬ be determined based on the characteristics available from the nozzle manufacturers. The throughput per spray nozzle is suitably 0.1 to 10 m ³ / h, often 0.5 to 5 nY 7 h.

The droplet diameter which is obtained during the spraying is usually from 10 to 1000 .mu.m, preferably from 50 to 500 .mu.m.

The reaction can also be carried out in apparatuses in which the monomer solution can be free in the form of monodisperse drops. Suitable for this purpose are apparatuses as described, for example, in US Pat. No. 5,269,980, column 3, lines 25 to 32.

A dripping by laminar jet decay, as in Rev. Sei. Instr., Vol. 38 (1966), pages 502 to 506, is also possible.

The use of spray nozzles for drop generation is preferred.

The reaction space of the polymerization reactor can be carried out in overpressure or under reduced pressure, and an underpressure of up to 100 mbar relative to the ambient pressure is preferred.

The polymerization reactor is preferably flowed through by a carrier gas. Be¬ preferred is the Gleichstromfahrweise, that is, the carrier gas flows through the poly merisationsreaktor from top to bottom.

The polymerization rate and the drying rate usually have different temperature dependence. This can mean, for example, that the sprayed drops dry before the desired conversion is achieved has been. Therefore, it is advantageous to influence the reaction rate and the drying speed separately.

The drying rate can be influenced by the water vapor content of the carrier gas. The water vapor content of the carrier gas is generally up to 90 vol .-%, preferably up to 50 vol .-%.

The rate of polymerization can be adjusted by the type and amount of the initiator system used. The use of azo compounds or redox initiators as initiators b) is advantageous for controlling the polymerization rate. The light-off behavior of the polymerization can be controlled better with azo compounds or redox initiators by selecting the initiator, initiator concentration and reaction temperature than, for example, with pure peroxide initiators.

Particularly advantageous are photoinitiators. When photoinitiators are used, the rate of drying over the temperature can be adjusted to the desired value without, at the same time, significantly affecting the formation of free radicals.

The carrier gas is to 19O ⁰ C, particularly preferably 90 to 140 ⁰ C, preheated advantageously upstream of the reactor to the reaction temperature of 70 to 250 ⁰ C, preferably 80th

The reaction offgas, i. the carrier gas leaving the reaction space can be cooled, for example, in a heat exchanger. In the process, water and unconverted monomer condense. Thereafter, the reaction gas can be at least partially reheated and recycled as recycle gas in the reactor. Preferably, the recycle gas is cooled so that the cooled recycle gas has the desired amount for the reaction of water vapor. Part of the reaction off-gas can be discharged and replaced by fresh carrier gas, wherein unreacted monomers contained in the reaction exhaust gas can be separated off and recycled.

Particularly preferred is a heat network, that is, a portion of the waste heat during cooling of the reaction exhaust gas is used to heat the carrier gas.

The reaction space can be heated. The trace heating is provided so ein¬ that the wall temperature is at least 5 ⁰ C above the tur Reaktorinnentempera¬ and the condensation is reliably avoided at the reactor walls.

The reaction product is obtained in the form of free-flowing polymer particles and can be removed from the reaction space in the customary manner, preferably at the bottom via a Conveying screw, and optionally further dried to the desired residual moisture content and ge wanted residual monomer content.

Preferably, at least 95% by weight of the particulate polymer has a particle diameter (particle size) of 5 to 1000 μm, preferably 10 to 500 μm, which are agglomerates of significantly smaller primary particles, in particular for larger particle diameters. The particle size distribution can be determined by conventional methods, for example analogously to the EDANA (European Disposables and Nonwovens Association) recommended test method No. 420.2-02 "Particle Size Distribution - Sieve Fraction".

The inventive method advantageously combines the preparation of a polymer dispersion with the drying of this dispersion in one step, wherein the heat of polymerization can be used simultaneously for drying. The displacer causes each of the droplets to form a polymer dispersion which dries during the spray polymerization. This results in primary particles that are significantly smaller than the source drops. During drying in the reactor, these primary particles form agglomerates together with the displacer. Thus, the polymers according to the invention are readily redispersible and readily soluble.

Another object of the present invention are water-soluble or water-swellable, powdery compositions, containing

i) at least 10% by weight, preferably at least 30% by weight, particularly preferably at least 50% by weight, of a polymerized water-soluble ethylenically unsaturated monomer a) or of at least two copolymerized water-soluble ethylenically unsaturated monomers a) and ii ) at least one displacer d), wherein the displacer ii1) at least 5 wt .-%, preferably at least 25 wt .-%, more preferably at least 35 wt .-%, of at least one displacer d1),

Ü2) at least 2 wt .-%, preferably at least 10 wt .-%, more preferably at least 20 wt .-%, at least one displacer d2) each based on the composition, or

Ü3) is a mixture of displacers d1) and d2)),

wherein the average molecular weight of component ii) is lower than the average molecular weight of component i). iii) optionally from 0.001 to 2% by weight, preferably from 0.01 to 1% by weight, particularly preferably from 0.02 to 0.5% by weight, of at least one polymerized crosslinker, wherein the sum of the above components is at most 100 wt .-%. Preferably, at least 95% by weight of the powdered composition has a particle diameter in the range of 5 to 1000 μm, preferably 10 to 500 μm.

The polymers or copolymers i) have average molecular weights of at least 1,000,000 g / mol, preferably of at least 2,500,000 g / mol, more preferably of at least 5,000,000 g / mol.

The polymers ii) have average molecular weights of at most 250,000 g / mol, preferably of at most 100,000 g / mol, more preferably of at most 50,000 g / mol.

In principle, the polymers i) and the polymers ii) can be composed of the same monomers, but remain distinguishable on account of their different average molecular weights (bimodal molecular weight distribution).

The compositions according to the invention preferably contain less than 10% by weight of water, more preferably less than 5% by weight, most preferably less than 2% by weight.

The water-soluble or water-swellable polymers which can be prepared by the process according to the invention are suitable for thickening and / or for absorbing liquids, in particular aqueous systems, and as absorbents in hygiene articles.

Non-crosslinked polymers dissolve in water, while crosslinked polymers swell strongly and also greatly increase the viscosity of the aqueous medium. Thus beispiels¬ have, 2 wt .-% aqueous solutions of the producible by the inventive process the polymer at pH 7 has a viscosity from 800 to 40,000 mPas (measured in a Brookfield viscometer, spindle 6, at 2O ⁰ C), the viscosity increases with the degree of crosslinking.

The polymers according to the invention can be used as thickeners for aqueous systems, for example as an additive to paper coating slips, as thickeners for pigment printing pastes and as an additive to aqueous paints such as facade paints. They can also be used in cosmetics, for example in hair cosmetic preparations such as conditioners or hair fixatives or as thickeners for cosmetic formulations, for the surface treatment of leather and for the absorption of aqueous liquids. The viscosity of 2% strength by weight aqueous solutions containing polymers prepared by the process according to the invention is at least 500 mPas at 23 ° C., preferably at least 1,000 mPas, more preferably at least 2,000 mPas.

Examples:

example 1

9 kg of 30 wt .-% aqueous polyvinylpyrrolidone and 10 g of 40 wt .-% aqueous E- thylendiaminotetraessigsäure were dissolved in 27.5 kg of water. The mixture was mixed with 12 kg of Pluriol E1500 (polyethylene glycol from BASF Aktiengesellschaft, DE). With triethanolamine, the pH was adjusted to 6.75. Within 10 minutes, 34.8 kg of 50% strength by weight aqueous acrylamide and 13.3 kg of 45% strength by weight aqueous with methylene chloride were subjected to quarternized vinylimidazole. The mixture was then treated with 30 g of Irgacure® 2959 (1- [4- (2-hydroxyethoxy) -phenyl] -2-hydroxy-2-methyl-1-propan-1-one from Ciba Spezialitätenchemie, CH) and 20 g of 2 , 2'-Azobis (2-amidinopropane) dihydrochloride (azo initiator V5Q from Wako Germany, DE). This mixture was sprayed in a heated, nitrogen atmosphere-filled spray tower (15O ⁰ C, 8 m height, 2 m width, gas velocity 0.1 m / s in cocurrent) sprayed. In the upper third of the spray tower, the drops passed 6 UV lamps (Fe-doped Hg emitters, each 6kW). At the bottom of the spray tower, a free-flowing, white powder was obtained. The average grain size was 20 μm. This powder was clearly dissolved in water. The 2% by weight solution had a pH of 7 and a viscosity of 1050 mPas.

Example 2

13.5 kg of 30% by weight aqueous polyvinylpyrrolidone and 10 g of 40% by weight aqueous ethylenediaminetetraacetic acid were dissolved in 25.5 kg of water. The mixture was admixed with 10.5 kg of Pluriol E1500 (polyethylene glycol from BASF Aktiengesellschaft, DE). With triethanolamine, the pH was adjusted to 6.75. Within 10 minutes, 34.8 kg of 50% strength by weight aqueous acrylamide and 7.3 kg of 60.7% strength by weight aqueous diallyldimethylammonium chloride were metered in. Subsequently, the research was Mi¬ with 30 g of Irgacure® 2959 (1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one from Ciba Specialty Chemicals, CH) ₁ 10 2.2 g ^1-azobis (2-amidinopropane) dihydrochloride (V50 azo initiator Wako Deutschland, Germany) and 10 g Ammoniumpero- peroxodisulfate was added. This mixture was sprayed in a heated spray tower filled sphere with Stickstoffatmo¬ (15O ⁰ C, 8m height, width 2 m, gas velocity 0.1 m / s in cocurrent). In the upper third of the spray tower, the drops passed 6 UV lamps (Fe-doped Hg emitters, each 6kW). At the bottom of the spray tower a free-flowing, white powder was obtained. The average grain size was 20 μm. This powder was clearly dissolved in water. The 2% strength by weight solution had a pH of 7 and a viscosity of 1,500 mPas.

Example 3

9 kg of 30 wt .-% aqueous polyvinylpyrrolidone and 10 g of 40 wt .-% aqueous E- thylendiaminotetraessigsäure were dissolved in 27.5 kg of water. The mixture was mixed with 12 kg of Pluriol E 1500 (polyethylene glycol from BASF Aktiengesellschaft, DE). With triethanolamine, the pH was adjusted to 6.75. Within 10 minutes, 34.8 kg of 50% strength by weight aqueous acrylamide, 13.3 kg of 45% strength by weight methyl chloride-quaternized vinylimidazole and 37.3 g of 98% strength by weight triallylamine were metered in. The mixture was then treated with 30 g Irgacure® 2959 (1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one from Ciba Spezialitätenchemie, CH) and 20 g 2,2'-azobis (2-amidinopropane) dihydrochloride (azo initiator V50 from Wako Germany, DE). This mixture was dripped in a heated, nitrogen atmosphere-filled spray tower (9O ⁰ C, 8m height, 2m width, Gasgeschwin¬ speed 0.1 m / s in cocurrent). The monodisperse drops had a diameter of 400 μm. In the upper third of the spray tower, the drops passed 6 UV lamps (Fe-doped Hg emitters, each 6kW). At the bottom of the spray tower a free-flowing, white powder was obtained. The average grain size was 220 μm. This powder was clearly dissolved in water. The 2% strength by weight solution had a pH of 7 and a viscosity of 6,000 mPas.

Example 4

13.5 kg of 30% by weight aqueous polyvinylpyrrolidone and 10 g of 40% by weight aqueous ethylenediaminetetraacetic acid were dissolved in 16.7 kg of water. The mixture was reacted with 13.5 kg of Pluriol E1500 (polyethylene glycol from BASF Aktiengesellschaft, DE). With triethanolamine, the pH was adjusted to 6.75. Within 10 minutes, 34.8 kg of 50% strength by weight aqueous acrylamide and 6.6 kg of 80% strength by weight aqueous methyl chloride quaternized dimethylaminoethyl acrylate were metered in. The mixture was then treated with 30 g of Irgacure® 2959 (1- [4- (2-hydroxyethoxy) phenyl] -2-hydroxy-2-methyl-1-propan-1-one from Ciba Spezialitätenchemie, CH) and 20 g 2,2'-azobis (2-amidinopropane) dihydrochloride (azo initiator V50 from Wako Germany, DE). This mixture was dripped in a heated, nitrogen atmosphere-filled spray tower (90 ⁰ C, 8m height, 2m width, gas velocity 0, 1 m / s in cocurrent). The monodisperse drops had a diameter of 400 μm. In the upper third of the spray tower, the drops passed 6 UV lamps (Fe-doped Hg emitters, each 6kW). At the bottom of the spray tower a free-flowing, white powder was obtained. The average grain size was 170 μm. This powder was clearly dissolved in water. The 2% by weight solution had a pH of 7 and a viscosity of 800 mPas. Example 5

7.7 kg of sodium sulfate, 12.8 kg of vinylpyrrolidone and 6.4 kg of 50 wt .-% aqueous quaternized with methyl chloride vinylimidazole were dissolved in 30 kg of water. 7.5 g of 20% strength by weight aqueous polyvinylamine (Catiofast® PR8106 from BASF Aktiengesellschaft, DE) were added as dispersing agent. With 5gew .-% sulfuric acid, the pH was adjusted to 6.75. Subsequently, the mixture was admixed with 50 g of 2,2'-azobis (2-amidinopropane) dihydrochloride (azo initiator V50 from Wako Germany, DE). This mixture was sprayed in a heated atmosphere with nitrogen gefüll¬ th spray tower (150 ⁰ C, 8m height, width 2 m, gas velocity 0.1 m / s in the direct-current). At the bottom of the spray tower a free-flowing, white powder was obtained. The average grain size was 22 μm. This powder was clearly dissolved in water. The 2% by weight solution had a pH of 7 and a viscosity of 2,000 mPas.

Example 6

7.7 kg of sodium sulfate, 12.8 kg of vinylpyrrolidone, 5 kg of 65% strength by weight aqueous diallyldimethylammonium chloride and 48 g of pentaerythritol tetraallyl ether were dissolved in 39 kg of water. 6.3 kg of 25% strength by weight aqueous polyvinylamine (Ca.tiofast.RTM. PR8106 from BASF Aktiengesellschaft, DE) were added as the dispersant. With 5gew .-% sulfuric acid, the pH was adjusted to 6.75. Subsequently, the mixture was admixed with 60 g of 2,2'-azobis (2-arnidinopropane) dihydrochloride (azo initiator V50 from Wako Germany, DE). This mixture was in a heated, re-filled with Stickstoffatmosphä¬ spray tower (8m 150 ⁰ C ₁ height, width 2 m, gas velocity 0.1 m / s in cocurrent). At the bottom of the spray tower a free-flowing, white powder was obtained. The average grain size was 24 μm. This powder was clearly dissolved in water. The 2% by weight solution had a pH of 7 and a viscosity of 4,000 mPas.

Example 7

7.7 kg of sodium sulfate, 12.8 kg of vinylpyrrolidone, 6.4 kg of 45% strength by weight aqueous methylated quaternized vinylimidazole and 48 g of triallylamine were dissolved in 34.7 kg of water. 6.3 kg of Sokalan® PA80 (acrylic acid from BASF Aktiengesellschaft, DE) were added as the dispersant. With 50gew .-% sulfuric acid, the pH was adjusted to 6.75. Subsequently, the mixture was admixed with 50 g of 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride (azo initiator V44 from Wako Germany, DE). This mixture was sprayed in a heated atmosphere with nitrogen gefüll¬ th spray tower (110 ⁰ C, 8m height, width 2 m, gas velocity 0.1 m / s in the direct-current). At the bottom of the spray tower became a free-flowing, white powder receive. The average grain size was 20 μm. This powder was clearly dissolved in water. The 2% by weight solution had a pH of 7 and a viscosity of 9,000 mPas.

Example 8

9 kg of Sokalan® HP22 (polyacrylic acid from BASF Aktiengesellschaft, DE) and 5.2 kg of Sokalan® CP2 (polyacrylic acid from BASF Aktiengesellschaft, DE) were dissolved in 2.9 kg of water. Within 10 minutes, 3 kg of acrylic acid was added. Subsequently, the mixture was admixed with 8 g of 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride (azo initiator V44 from Wako Germany, DE). This mixture was sprayed in a heated, nitrogen atmosphere-filled spray tower (110 ⁰ C ₁ 8m height, 2m width, gas velocity 0.1 m / s in cocurrent). At the bottom of the spray tower a free-flowing, white powder was obtained. The average grain size was 25 μm. This powder was clearly dissolved in water. The 2% by weight solution had a pH of 7 and a viscosity of 5,000 mPas.

Example 9

9 kg of Sokalan® HP22 (polyacrylic acid from BASF Aktiengesellschaft, DE) and 5.2 kg of Sokalan® CP2 (polyacrylic acid from BASF Aktiengesellschaft, DE) were dissolved in 2.9 kg of water. Within 10 minutes, 3 kg of acrylic acid and 9 g of triallylamine were added. Subsequently, the mixture was admixed with 8 g of 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride (azo initiator V44 from Wako Germany, DE). This mixture was in a heated, filled with nitrogen atmosphere spray tower (110 ⁰ C, 8m height, 2m width, gas velocity 0.1 m / s in cocurrent) sprayed. At the bottom of the spray tower a free-flowing, white powder was obtained. The average particle size was 22 μm. This powder was clearly dissolved in water. The 2% strength by weight solution had a pH of 7 and a viscosity of 40,000 mPas.

Example 10

12 g of Pluriol® P600 (polypropylene glycol from BASF Aktiengesellschaft, DE) and 5.2 kg of Sokalan® CP2 (polyacrylic acid from BASF Aktiengesellschaft, DE) were dissolved in 10.6 kg of water. Within 10 minutes, 3 kg of acrylic acid was added. Subsequently, the mixture was admixed with 8 g of 2,2'-azobis [2- (2-imidazolin-2-yl) propane] dihydrochloride (azo initiator V44 from Wako Germany, DE). This mixture was in a heated, filled with nitrogen atmosphere spray tower (11O ⁰ C, 8m height, 2m width, gas velocity 0.1 m / s in cocurrent) sprayed. At the bottom of the spray tower a free-flowing, white powder was obtained. The average grain size was 22 μm. This powder was clearly dissolved in water. The 2 wt .-% solution had a pH of 7 and a viscosity of 500 mPas.

Claims

claims

A process for producing polymers by spray polymerization, wherein an aqueous monomer solution containing

a) at least one water-soluble ethylenically unsaturated monomer, b) at least one initiator and c) water,

sprayed into a reaction space and polymerized, characterized gekennzeich¬ net, that the monomer solution additionally contains at least one displacer d), wherein the displacer

2. The method according to claim 1, characterized in that the Verdrän¬ ger d1) Polyvinyipyrrolidon, polyethylene glycol, polyvinylamine, polyacrylic acid, an acrylic acid / maleic acid copolymer and / or a graft polymer of vinyl acetate and / or vinyl propionate on polyethylene glycol.

3. The method according to claim 1 or 2, characterized in that the displacer d2) is an inorganic salt.

4. The method according to any one of claims 1 to 3, characterized in that the monomer a) is acrylic acid, vinylpyrrolidone, quaternized vinylimidazole, acrylamide, quaternized dimethylaminoethyl acrylate and / or Diallyldimethylammo- nimchlorid.

5. The method according to any one of claims 1 to 4, characterized in that the initiator b) is an azo compound, a redox initiator and / or a photoinitiator.

6. The method according to any one of claims 1 to 5, characterized in that the monomer solution additionally contains a complexing agent.

7. The method according to any one of claims 1 to 6, characterized in that the reaction is carried out in the presence of an inert carrier gas.

8. Water-soluble or water-swellable, powdery compositions, ent

i) at least 10 wt .-% of a polymerized water-soluble ethylenically unsaturated monomer a) or at least two copolymerized water-soluble ethylenically unsaturated monomers a) and ii) at least one displacer d), wherein the displacer ii1) at least 5 wt .-% of at least one displacer d1), ü2) at least 2 wt .-% of at least one displacer d2) 10 each based on the composition, or

Ü3) is a mixture of displacers d1) and d2)),

wherein the average molecular weight of component ii) is lower than the average molecular weight of component i).

15th

9. Use of the polymers according to claim 8 for thickening and / or Ab¬ sorption of aqueous liquids.

10. Thickened aqueous liquids containing a polymer according to claim 8.