DE10260989A1 - Use of water-soluble polymers as drying aids for the production of redispersion powders and / or powdery, polymeric dispersants - Google Patents

Abstract

The use of water-soluble polymers consisting of a) monoethylenically unsaturated monomers bearing acid groups in acidic, partially or completely neutralized form and b) further monomers copolymerizable with the monomers a) as drying agents for the production of redispersion powder and / or powdery, polymeric is claimed dispersant. The water-soluble polymers should contain at least 20% by weight of the monomers a) and at most 80% by weight of the monomers b) and should be added to the production process in proportions up to a maximum of 50% by weight in the form of aqueous solutions. In this way, in particular in spray-drying processes, powdery, polymeric products with a residual moisture content of <2% by weight can be obtained, which are added to mineral systems in proportions of 0.05 to 5% by weight as dispersing agents or as redispersing powder in mineral-setting building materials, in adhesives or as a sole binder.

Description

The present invention relates to the use of water-soluble polymers of defined composition as Drying aids for the production of redispersible powders and / or powdery, polymeric dispersant.

Aqueous polymer dispersions are generally known. It is about systems with redispersing properties that are used in essentially spherical balls of tangled threads Polymer chains (so-called polymer particles) in disperse distribution contain. Just like polymer solutions when evaporating the Solvents have aqueous polymer dispersions on evaporation of the aqueous dispersion medium has the potential to form Polymer films, which is why they are used especially as binders, adhesives and coating agents are used.

A disadvantage of the application of the aqueous polymer dispersions is that they do not fully satisfy as a form of sale. So your transportation implies from the place of manufacture to the place of use in addition to transporting the modified Polymerisats always the transport of what is actually readily available everywhere Mixing water. Aqueous polymer dispersions can also be used mineral binders for the purpose of modifying them only on Place of use must be added, as these would otherwise be used Harden. Furthermore, in the polymer dispersions, due to their complex composition, during storage and transport ready-to-use formulation problems due to phase separation, Thickening, damage caused by frost and bacteria.

A desirable form of aqueous polymer dispersions therefore represents when water is added, it is a polymer powder which is redispersible is. A great advantage of redispersion powders over liquid ones Dispersions is that you can make dry mortar mixes that only need to be mixed with water at the construction site. This brings many advantages such as increased occupational safety, safe handling and easier container emptying.

Dispersants and especially cement dispersants are used in Construction area often added hydraulically curing building materials to sufficient flowability and workability of the concrete or To achieve mortar, which is particularly true at low so-called w / z Values is important. The smaller the water / cement (w / z) ratio is, the stronger the mechanical resistance and the Durability of hardened cementitious building materials like concrete or mortar too. Take consistency and processability of these building materials however, with decreasing w / c ratios.

The melamine-formaldehyde-sulfite as well as used for a long time Naphthalenesulfonic acid-formaldehyde resins are often not sufficient these days more the requirements because u. a. great value for a long time Processability with rapid strength development and high mechanical resistance of the end product becomes. An additional problem arises when using such Superplasticizer in mining (as shotcrete) and indoors, where it is used Release of the contained in the products due to manufacturing toxicologically questionable formaldehyde and thus too occupational hygiene can come.

For this reason, cement dispersants have been based for some time Polycarboxylate ethers used which meet the requirements mentioned above able to fulfill far better. These will be polycarboxylate ethers by means of radical polymerization reactions, preferably in aqueous Medium produced and accumulate as an aqueous solution. The polymerization but can also in mixtures of water with organic solvents or in an emulsion or in substance.

In applications where the polymers are used as an additive in the factory prefabricated dry mixes are needed is the use aqueous preparations are unfavorable, even in this case completely excluded. It is therefore mandatory for such areas required, all additives and thus also the dispersant in To provide powder form.

A particularly convenient method of transferring an aqueous Polymer dispersion in a redispersible polymer powder or Powdery dispersant is the process of spray drying, at which the polymer dispersion sprays in a warm air stream and is drained. Because of the modification of mineral binders or as a binder for plastic plasters to be used in the polymer Usually have a glass transition temperature below 60 ° C the procedure of the without using spray aids Spray drying to make your redispersible polymer powder either not at all or only in an uneconomical one Apply temperature range. Another disadvantage of the without Spraying aids by drying aqueous polymer dispersions polymer powder produced is further that its redispersibility Addition of water as a rule is not fully satisfactory, as that at the Redispersion resulting polymer diameter distribution in usually significantly different from that in the aqueous starting dispersion (Primary particle diameter distribution) differs.

It is also known that in the production of powder Dispersants that have a high water solubility in the course of conventional drying methods often result in insoluble gels, which in turn have a poor effect (JP 07-14829).

Furthermore, one has to deal with the problem that not insignificant amounts of polymer powder on the wall of the Stick the drying tower in place, which drastically reduces the product yield.

Another disadvantage of the conventional spray drying process This type of polymer consists of that before drying often not insignificant amounts of inorganic additives are added , due to which the active component in the resulting Powder decreases; or else the polymer becomes from the carrier material absorbed, which in turn leads to significant loss of effectiveness in the Application leads.

Furthermore, when adding inorganic materials with a relative high density in the polymer solution easily sedimentation of the Carrier material instead. This happens during the transportation of the Polymer solution from the storage container to the dryer unit, see above result in strong inhomogeneities in the end product.

To solve these problems, an attempt has been made to place the polymer solution in or add several reducing agents and then by kneading and mixing to dry (EP 1 052 232 A1). However, this process is very complex, since the concentrated polymer solution mostly under vacuum and inert gas needs to be dried. In addition, in the pulverization of highly viscous solutions the motor of the drying units often up to whose performance limit is claimed, which leads to automatic Shutdown and thus leads to economically unfavorable downtimes. In addition, such procedures are no longer a safe workflow given. After all, with these processes the solid polymer often has to still crushed and / or ground, which is an additional Step is necessary and causes additional costs.

Compounds have long been known whose addition to aqueous Polymer dispersions have the appearance of being undesirable mentioned, irreversible secondary particle formation when drying reduced. These connections are under the generic term Drying aids summarized. They are often special also known as spraying aids, since the one already mentioned Spray drying to a particularly large extent, the formation of irreversible Promotes secondary particles. The spray aids prevent in general caking or clumping during the drying process and usually reduce training at the same time Drying wall sticking polymer coating during spray drying and them thus increase the powder yield.

So z. B. in DE-OS 20 49 114 and DE-OS 20 49 114 Condensation products from melamine sulfonic acid and formaldehyde as Desiccant recommended for aqueous polymer dispersions, during DE-OS 24 45 813 and EP-A 78 449 condensation products Reveal naphthalenesulfonic acid and formaldehyde.

EP-A 407 889 recommends condensation products from phenolsulfonic acid and Formaldehyde as a drying agent for aqueous polymer dispersions.

DE-OS 24 45 813 recommends sulfone groups Condensation products from aromatic mono- or polynuclear Hydrocarbons and formaldehyde as drying aids while DE-OS 41 18 007 condensation products from sulfonated phenols, Urea, other organic nitrogen bases and formaldehyde as Desiccant describes.

In DE-OS 33 44 242, lignin sulfonates are used as drying aids called.

DE-OS 22 38 903 and EP-A 576 844 describe the use of poly N-vinylpyrrolidone as drying aid, EP-A 62 106, EP-A 601 518 and EP-PS 632 096 the use of polyvinyl alcohols as Drying aids.

DE-OS 195 39 460, EP-A 671 435 and EP-A 629 650 disclose homo- and Copolymers of 2-acrylamido-2-methylpropanesulfonic acid as Suitable drying aids for aqueous polymer dispersions.

EP-A 467 103 is the preparation of polymer powders redispersible in aqueous media by drying and with the addition of copolymers of 50 to 80 mol% of an olefinically unsaturated mono- and / or dicarboxylic acid and 20 to 50 mol% of a C ₃ - bis C ₁₂ - alkene and / or styrene as drying aids.

According to DE-OS 44 06 822, graft polymers are made from polyalkylene oxides and unsaturated mono- / dicarboxylic acids or their anhydrides derivatization with primary / secondary amines or alcohols Recommended as a drying aid.

DE-OS 33 44 242 and EP-A 536 597 name starch and starch derivatives as suitable drying aids, while also DE-OS 33 42 242 Cellulose derivatives disclosed as suitable drying aids.

DE-OS 493 168 finally recommends organopolysilanes as Drying aids.

The spray aids known from the prior art described have many disadvantages: namely, those from DE-OS 24 45 813, EP-A 78 449 and EP-A 407 889 known naphthalenesulfonic acid or Phenolsulfonic acid-formaldehyde condensation products used, so you get colored products. Condensation products from sulfonated Phenols, ureas, other nitrogen bases and formaldehyde as Spray aids, as described in DE-OS 41 18 007, are indeed according to the Spray drying knows, but they tend in a strongly alkaline environment like it is typical of mineral binders, and in the presence of metal ions for re-coloring. Longer storage also reduces the Redispersibility, since the powder particles under the weight of the Powders tend to stick or block together. On another disadvantage when using the above formaldehyde-containing condensation products is that their aqueous solutions have a not inconsiderable content of free Have formaldehyde. This results in drying Formaldehyde contamination of the exhaust air flow, which is costly Exhaust air cleaning is necessary.

Another disadvantage of the manufactured in this way Redispersion powder is the possible release of formaldehyde or after their application due to decomposition reactions such as can run in the basic environment of a cement matrix. The consequence of which is that such redispersible dispersions, especially in the Indoor use, due to ecological and health aspects, are increasingly avoided.

Those known from DE-OS 41 18 007 and EP-A 467 103 Spray aids worsen the product properties sprayed polymers as binders in use. A disadvantage of the spray aids, are completely or partially neutralized water-soluble copolymers in addition to hydrophobic monomers also 50 to 80 mol% of monomers containing carboxyl groups contained in copolymerized form (EP-A 467 103). On the basis of such Polymer powders, for example, cannot be formulated into plastic plasters, whose water resistance is fully satisfied. This also applies to the Spraying aids based on vinyl pyrrolidone / vinyl acetate according to EP-A 78 449 or polyvinyl alcohol according to DE-OS 22 14 410. Another disadvantage of Spray aids of the prior art are based on the fact that they the hardening time of the modified mortar or Do not emphasize concretes in a neutral manner, but generally solidify strongly delay. The spray aids according to EP-A 629 650 are included as aids the drying of aqueous polymer dispersions is also unsuitable.

It is undisputed that powders are not only logistical and economical Advantages over aqueous preparations, in particular none Transport of water takes place, but also a number of technical ones Benefits. For example, there is no need to add biocides Stabilization purposes as well as those that may be complex Tank hygiene measures. In general, the use of powders desirable.

The object of the present invention is therefore to suitable drying aids for the production of Redispersion powders and / or powdery, polymeric To provide dispersants. With these drying aids the original polymer properties in terms of effectiveness especially in hydraulic systems and not be negatively influenced generally no undesirable when processing in the building material system Side effects such as discoloration or an increase in viscosity to adjust. The drying aid should also work well with the Redispersion powder or the polymeric dispersant compatible be, so that a possible phase separation or a separation of the Components or the components before the drying process be avoided. The drying aids are also intended for production of polymer powders redispersible in the aqueous medium be used as an additive in mineral binders can be, but also for example for the production of plastic plasters are suitable. Finally, the polymer powder obtained in this way should be free of toxicologically questionable components such. B. formaldehyde.

• a) monoethylenisch ungesättigten, Säuregruppen tragenden Monomeren in saurer, teilweise oder vollständig neutralisierter Form der Reihe Acrylsäure, Methacrylsäure, 2-Ethylacrylsäure, 2-Propylacrylsäure, Vinylessigsäure, Croton- und Isocrotonsäure, Maleinsäure, Fumarsäure, Itaconsäure, Citraconsäure, Vinylsulfonsäure, Methallylsulfonsäure, 2-Acrylamido-2-methylpropylsulfonsäure, 4-Vinylphenylsulfonsäure, Vinylphosphonsäure, (Halb-)Ester und/oder Amide der genannten Carbonsäuren sowie deren Gemische und/oder deren Anhydride und
• b) weiteren mit den Monomeren a) copolymerisierbaren Monomeren der Reihe (Meth)Acrylamid, (Meth)Acrylnitril, (Meth)Allylalkohol, Hydroxyalkyl(meth)acrylat, mit Alkyl = C₁ bis C₅, Hydroxyalkylpolyethylenoxy- und -propylenoxy- bzw. -butylenoxy(meth)-acrylat mit Alkyl = C₁ bis C₅, Vinylether wie z. B. Hydroxy- und Alkoxypolyethylenoxy- bzw. -polypropylenoxyvinylether sowie analoge Allylether mit bis zu 10 sich wiederholenden Einheiten, N-Vinylacetamid, N-Vinyllactame, N-Vinylpyrrolidon, N-Vinylimidazol, siliciumfunktionelle Comonomere, wie (Meth-)Acryloxyalkyltri- (alkoxy)-Silane, Vinyltrialkoxysilane und Vinylmethyldialkoxysilane mit C₁ bis C₅-Alkyl- bzw. Alkoxy-Resten sowie deren Derivate und deren Mischungen

als Trocknungshilfsmittel für die Herstellung von Redispersionspulvern und/oder pulverförmiger, polymerer Dispergiermittel. This object was achieved by the use according to the invention of water-soluble polymers consisting of

• a) monoethylenically unsaturated, acid group-bearing monomers in acid, partially or completely neutralized form of the series acrylic acid, methacrylic acid, 2-ethylacrylic acid, 2-propylacrylic acid, vinyl acetic acid, croton- and isocrotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, vinyl sulfonic acid, methallylsulfonic acid -Acrylamido-2-methylpropylsulfonic acid, 4-vinylphenylsulfonic acid, vinylphosphonic acid, (half) esters and / or amides of the carboxylic acids mentioned and their mixtures and / or their anhydrides and
• b) further monomers copolymerizable with the monomers a) from the series (meth) acrylamide, (meth) acrylonitrile, (meth) allyl alcohol, hydroxyalkyl (meth) acrylate, with alkyl = C ₁ to C ₅ , hydroxyalkylpolyethyleneoxy and propyleneoxy or -butyleneoxy (meth) acrylate with alkyl = C ₁ to C ₅ , vinyl ethers such as. B. hydroxy and alkoxypolyethyleneoxy or polypropyleneoxyvinyl ether and analog allyl ethers with up to 10 repeating units, N-vinyl acetamide, N-vinyl lactams, N-vinyl pyrrolidone, N-vinyl imidazole, silicon-functional comonomers, such as (meth) acryloxyalkyltri- (alkoxy ) -Silanes, Vinyltrialkoxysilane and Vinylmethyldialkoxysilane with C ₁ to C ₅ alkyl or alkoxy radicals and their derivatives and mixtures thereof

as drying aids for the production of redispersion powders and / or powdery, polymeric dispersants.

Surprisingly, it has been shown that those used according to the invention Polymers in spray drying are therefore extremely effective since one Gluing the polymer powder during production is now advantageous is prevented. It is also surprising that the spray aids according to the invention can also be used in amounts which are greater than quantities required for spray drying go out while doing so nevertheless, the tendency of the dispersion powder to block is clear is reduced without negatively affecting the physical properties of the to act as mineral binding binder systems. Completely It has also been shown, surprisingly and unpredictably, that the redispersible produced by the claimed use Powder the flow properties and thus the workability and the Surface quality of mineral-setting binders influence positively without being dispersive to the individual Components to work.

Concerning. the powdery, polymeric dispersant was surprising found that they are described by using the water-soluble polymers especially with conventional spray drying in very good yields and without incrustations on the dryer wall High-quality powder form can be made, with no subsequent Grinding and sieving steps are required. That this is additional to the requirements requested by the task claimed use is possible, could not have been foreseen.

The water-soluble intended for the use according to the invention Polymers are known per se. DE-OS 196 25 984 describes this Process for the preparation of an aqueous polymer dispersion by Polymerization of a) monoethylenically unsaturated acid groups bearing monomers in acid, partially or completely neutralized Form in the presence of hydrophilized, vegetable and / or animal and / or technical fats or oils with possibly b) others with the Monomers a) copolymerizable monomers, where as monomers a) u. a. Acrylic acid, methacrylic acid and methallylsulfonic acid are used become. However, these aqueous polymer dispersions are found exclusively for the emulsification of hydrophobic compounds or for Manufacture and processing of leather and fur use. DE-OS 195 16 957 describes u. a. a process for the production of water-soluble polymers suitable for detergents and cleaning agents from monoethylenically unsaturated dicarboxylic acids, monoethylenic unsaturated sulfonic acid or sulfate group-containing monomers and monoethylenically unsaturated monomers after acid hydrolysis or alkaline saponification to form monomer units with covalent bound hydroxyl groups can be converted and if necessary further radically copolymerizable monomers, the Target polymers by radical polymerization and hydrolysis or Saponification can be formed in aqueous media at 40 to 180 ° C. Although is in this document also the use of the polymers thus obtained described as a dispersant, but not their suitability as Drying aids in the manufacture of redispersible Polymer powders or powdery, polymeric dispersants.

Within the scope of the present invention, in particular water-soluble polymers suitably shown, the at least 20 wt .-% Monomers a) and at most 80 wt .-% of monomers b).

It has proven to be just as advantageous in the context of the invention Use shown when the acid groups are the monoethylenic unsaturated monomers a) before, during or after Polymerization were at least partially neutralized, which in particular with the help of alkali and / or alkaline earth metal hydroxides, ammonia, a Amine, polyamine or amino alcohol should take place.

For certain applications, it may prove to be advantageous if the water-soluble polymer has an average molecular weight M _n of 1000 to 100,000 g / mol and preferably between 2000 and 70,000 g / mol, particularly preferably between 3000 and 50,000 g / mol, which also takes into account the present invention.

With regard to the monomers b), it should be noted that, in principle, the Chain length of the polyethylene building blocks of the monomers is not limited, that, however, n ≤ 10 shows certain advantages.

From the range of possible manufacturing processes for the water-soluble The present invention preferably claims polymers radical polymerisation in water or in a water-containing Mixture with a maximum of 30% by weight of an organic solvent, but also Emulsion polymerizations or a solvent-free Bulk polymerization.

In the context of the present invention are intended as drying aids in particular aqueous solutions are used, the 1 to 99 wt .-% of the water-soluble polymer, with amounts between 20 and 70 wt .-% preferred and those between 35 and 60 wt .-% entirely are particularly preferred.

Regardless of how the water-soluble polymers were obtained or whether the drying aids in powder form or in aqueous Solution are used, the present invention provides that the Drying aids in the manufacturing process of dispersants in Proportions up to a maximum of 50% by weight and preferably between 5 and 30% by weight, based on the dispersant or the polymer dispersion, be fed.

Since these dispersants are known in particular with the help of Spray drying processes obtained in powder form are taken into account the present invention also the use of drying aids preferably in these processes. The drying aid should do this in particular in a contact dryer, a fluidized bed dryer or Belt dryers can be used or in a drying process using With the help of heat radiation such. B. infrared or microwave radiation is carried out.

The water-soluble polymers are preferably intended for the preparation a dispersant can be used, the polyoxyalkylene-containing Structural elements, carboxylic acid and / or carboxylic anhydride Monomers consists, as in particular from the patent documents WO 97/39 037, EP-PS 0 610 699 or WO 98/28 353 are known.

With regard to the powdery, polymeric dispersant Invention before that the drying aid is used in such a way that a powdery polymeric dispersant is obtained which has a residual moisture content of <5% by weight and preferably <2% by weight.

So that the polymeric dispersant powder even at higher Temperatures during transport and storage or in accordingly hot climates are resistant to sticking and caking remain, it can be quite useful with the drying aid prepared polymeric dispersant after its manufacture corresponding more or less fine quality improvement Add additives. The type of these additives is not subject to any particular limitation, however, should be the respective materials well tolerated physically and chemically with the dispersant. The the dispersing effect of the agent should not be adversely affected and the quality-improving properties should already stand out Stop adding only small amounts of additives. In this Context, the present invention sees quality-improving Additives in particular the use of chalk, silica, calcite, Dolomite, quartz powder, bentonite, pumice powder, titanium dioxide, aluminum oxide, Fly ash, cements, silicates, talc, mica, anhydrite, lime, diatomaceous earth, Gypsum, magnesite, alumina, kaolin, slate and stone powder, barium sulfate as well as mixtures thereof. Those should be particularly preferred quality-improving additives in finely divided form and here used in particular with a particle size of 0.1 to 1000 microns become.

The using the drying aids according to the invention polymeric dispersants obtained are mainly used as additives for Construction chemical applications suitable and can according to the invention preferably mineral building materials in proportions of 0.05 to 5% by weight, based on the setting basic system, the Invention in particular the addition of those obtained according to the invention powdery, polymeric dispersants for mineral systems, such as bituminous building materials, on hydraulically setting binders, like cement, or on latent hydraulically setting binders based building materials, plaster, anhydrite or other Calcium sulfate-based building materials, ceramic materials, refractory materials, Oilfield building materials and dispersion-based building materials.

In this context, the present invention prefers one Variant in which the drying aid of an aqueous dispersion of a redispersible organic binder consisting of a Base polymer from the group of vinyl ester, styrene, acrylate, Vinyl chloride or polyurethane polymers is added.

• a) bis zu 30 Massen-% eines Zementverflüssigers und/oder
• b) bis zu 30 Massen-% eines Schutzkolloids wie z. B. Polyvinylalkohol und/oder
• c) bis zu 2 Massen-% mindestens einer oberflächenaktiven Substanz wie Emulgatoren oder Netzmittel und/oder
• d) bis zu 3 Massen-% eines Verdickungsmittels wie Polyacrylsäure und/oder
• e) bis zu 2 Massen-% eines Entschäumers

enthalten. The aqueous dispersion of a redispersible organic binder can additionally and in each case based on the base polymer

• a) up to 30% by mass of a cement plasticizer and / or
• b) up to 30% by mass of a protective colloid such as e.g. B. polyvinyl alcohol and / or
• c) up to 2% by mass of at least one surface-active substance such as emulsifiers or wetting agents and / or
• d) up to 3% by mass of a thickener such as polyacrylic acid and / or
• e) up to 2% by mass of a defoamer

contain.

• a) 1 bis 30 Gew.-%, bezogen auf das Gesamtgewicht polymerer Bestandteile, an feinem Antiblockmittel wie fein gemahlene Aluminiumsilikate, Kieselgur, kolloidales Silicagel, pyrogene Kieselsäure, Fällungskieselsäure, Mikrosilica, Kaolin, Talkum, Zemente, Diatomeenerde, Calcium- und/oder Magnesiumcarbonat sowie Magnesiumhydrosilikat und
• b) 0,1 bis 10 Gew.-%, bezogen auf das Basispolymerisat, an weiteren Zuschlagstoffen zugemischt sind.

Within the scope of this invention and with regard to the products produced with the drying aids in the form of redispersion powders, it is proposed that these

• a) 1 to 30 wt .-%, based on the total weight of polymer components, of fine antiblocking agent such as finely ground aluminum silicates, diatomaceous earth, colloidal silica gel, pyrogenic silica, precipitated silica, microsilica, kaolin, talc, cements, diatomaceous earth, calcium and / or Magnesium carbonate and magnesium hydrosilicate and
• b) 0.1 to 10% by weight, based on the base polymer, of further additives are admixed.

With regard to the redispension powder obtained, is preferred can be seen that these in mineral setting building materials as well as in Tile adhesives, fillers, gypsum building materials, lime mortars, Cement mortars, plasters and dry mortars are used. Is possible but also their use in adhesive compositions and Paints and / or as sole binders for coating agents.

Finally, one of the present invention is also redispersing active powder comprises which using the water-soluble Polymers as drying aids or according to one of the described Variants can be produced.

• - 10 bis 60 Gew.-% eines mineralischen Bindemittels,
• - 0,1 bis 20 Gew.-% eines mit dem Trocknungshilfsmittel gemäß einem der Ansprüche 1 bis 9 hergestellten Polymerisatpulvers,
• - bis zu 25 Gew.-% an üblichen Hilfsmitteln, jeweils bezogen auf die Gesamtzusammensetzung und
• - als Restmenge Zuschläge wie Sand, Füllstoffe, Pigmente, natürliche Fasern und/oder synthetische Fasern enthält.

A building material composition is also claimed, which

• 10 to 60% by weight of a mineral binder,
• 0.1 to 20% by weight of a polymer powder prepared with the drying aid according to one of claims 1 to 9,
• - Up to 25 wt .-% of conventional auxiliaries, each based on the total composition and
• - Contains additives such as sand, fillers, pigments, natural fibers and / or synthetic fibers as a residual quantity.

With the present use of water-soluble polymers as drying aids for production of redispersible powders and / or powdery, polymeric Dispersants can now be the otherwise problematic Spray drying processes can be carried out without difficulty since the so far used especially in aqueous solutions Starting polymers of the dispersants even under extreme Now no longer decompose the temperature load and the resulting Products as polymer powders are no longer z. B. occur in oily form or clump together. The ones that have occurred almost regularly since then Sticking to the dryer wall can be avoided entirely, elaborate grinding steps with subsequent sieving as they go through the proportions of inorganic inert materials that have occurred to date have been eliminated Completely.

The following examples illustrate the advantages of use according to the invention.

Examples 1. Production of redispersible powders

To produce the respective solutions of inventive examples 1 to 4 aqueous dispersions stabilized with polyvinyl alcohol each with a solids content of 50% by weight based on a vinyl acetate-ethylene Copolymer (dispersion 1) or based on an ethylene-vinyl chloride Vinyl laurate terpolymer (Dispersion 2) from Wacker Polymer Systems GmbH used.

In addition, the following synthesis examples were used Drying aids used:

Synthesis example 1

In a reaction vessel equipped with a reflux condenser, stirrer, The thermometer, dropping funnel and nitrogen gas were placed in 460 g of water 98 g maleic anhydride, 33.2 g 2-acrylamido-2-methylpropanesulfonic acid (AMPS), 65 g hydroxypropyl acrylate and 36 g acrylic acid dissolved. Under The reaction solution was supplied with nitrogen in a water bath at 60.degree heated and there were 4.3 g of ammonium peroxodisulfate and 8.5 g Mercaptoethanol added dropwise in 20 g of water. The reaction mixture was Stirred for 2 hours at 70 ° C under nitrogen, then on Cooled to room temperature and neutralized to pH 7.0 with sodium hydroxide solution. The resulting product was a clear polymer solution with one Solids content of 44 wt .-% and a molecular weight Mw ~ 5000.

Synthesis example 2

According to the procedure of Synthesis Example 1, 350 g Water 46 g acrylic acid, 43.3 g hydroxypropyl acrylate, 43.4 g itaconic acid and 30 g sodium methallylsulfonic acid in the presence of 2.5 g Ammonium peroxodisulfate and 5.0 g of 2-mercaptoethanol reacted. The The result was a clear polymer solution with a solids content of 40% by weight. and a molecular weight Mw ~ 7000.

The following solutions were used in the spray drying process:

example 1

4000 parts by weight of dispersion 1 were mixed with 750 g of a 44% aqueous solution of a drying aid according to synthesis example 1 (corresponds to 16.5 mass% copolymer per 100 mass% Dispersion solid) mixed homogeneously and with 1075 g of water in one Solids content of 40% by mass diluted.

Example 2

4000 parts by weight of dispersion 1 were mixed with 900 g of a 40% aqueous solution of a drying aid according to synthesis example 2 (corresponds to 18 mass% copolymer per 100 mass% Dispersion solid) mixed homogeneously and with 1000 g of water in one Solids content of 40% by mass diluted.

Example 3

4000 parts by weight of dispersion 2 were mixed with 795 g of a 44% strength aqueous solution of a drying aid according to synthesis example 1 (corresponds to 17.5 mass% copolymer per 100 mass% Dispersion solid) mixed homogeneously and with 1080 g of water in one Solids content of 40% by mass diluted.

Example 4

4000 parts by weight of dispersion 1 were mixed with 1000 g of a 40% strength aqueous solution of a drying aid according to synthesis example 2 (corresponds to 20 mass% copolymer per 100 mass% Dispersion solid) mixed homogeneously and with 1000 g of water in one Solids content of 40% by mass diluted.

Example 5 comparison

Vinnapas RE 5011, a commercially available redispersible powder from Wacker Polymer Systems GmbH.

The subsequent spray drying was carried out in a laboratory dryer Niro carried out. The aqueous to be dried in each case Polymer dispersion was sprayed using a rotating disc, with nitrogen pre-compressed to 4 bar. The inlet temperature of the dryer gas was 130 ° C, the The initial temperature was 60 to 64 ° C.

The powders obtained from the solutions of Examples 1 to 4 are in aqueous medium redispersible in a completely satisfactory manner. As the Table 2 shows the redispersion powders produced in this way were significant better flow properties than Comparative Example 5, the polymeric drying agents used in each case in pure Portland cement or alumina cement mortars themselves are not have a dispersing effect (see test formulation 2 and table 2).

Due to the very good leveling properties, the redispersion powders produced according to the invention also have very good self-healing properties without delaying the setting behavior of the composition (see Table 1). The self-healing property is assessed by a so-called knife cut test. The setting behavior is characterized on the one hand by the determination of the Shore D hardness and on the other hand by the solidification behavior according to Vicat. Test recipe 1

Table 1 Technical testing

Mixing instructions S min. sprinkle, then
S min. swamp, then
2 min. stir with a spoon, then
1 min. Ripening, and
1 min. stir with a spoon

Flow according to EN 12706: with ring d = 30 mm, h = 50 mm The flow measurement or the knife cut test were carried out after x min. carried out after the start of mixing.

yardstick Knife-cut test

Note 1: The cut runs completely

Note 2: Cut runs, but visible

Note 3: Cut runs, but edge visible

Note 4: cuts run, but the edge is clearly visible

Grade 5: cuts run badly

Grade 6: cuts run badly, incision

Note 7: Cut does not run

Test formulation 2

The mortar mixtures were prepared in accordance with DIN EN 196-1, Section 6.3. The flow behavior was tested in a gutter test in accordance with the grouting directive of the German Concrete Association. V. (Version from September 1990, editorially revised 1996) after 5, 30 and 60 min. determines Table 2

II. Production of powdered dispersants 1. Comparative examples drying tests Example 1.1

An aqueous dispersant solution prepared in accordance with DE 195 13 126 was rotated in for 2 hours in a rotary evaporator at 80 ° C. and 100 mbar. A very tough, waxy mass was formed which was finally scraped off the glass wall when warm. After cooling to room temperature, wax-like, sticky polymer lumps resulted ( Fig. 1), which could not be ground due to their consistency. A transfer of the aqueous polymer solution into its corresponding polymer powder is not possible in this way.

Example 1.2

An aqueous dispersant solution prepared according to DE 199 26 611 A1 was applied in a thin layer of about 3 mm on a baking sheet and dried in a drying cabinet at 130 ° C. for 4 hours. As the solids content increased, the solution became increasingly viscous and bubbles formed. The consistency of the hot concentrate was sticky and elastic. When cooling to temperatures below 40 ° C, the mass solidified into a brittle layer that was scraped off the sheet. It was observed that the rubber-elastic polymer mass no longer completely dried out with increasing layer thickness. This polymer mass is therefore still slightly sticky after cooling to room temperature and the residual moisture content fluctuates between 4 and 10%. Furthermore, inhomogeneities occurred when the polymer solution was dried from a layer thickness of approx. 2 mm, which can be perceived optically simply by different coloring of the top and bottom polymer layers ( Fig. 2).

Example 1.3

An aqueous dispersant solution prepared according to DE 199 26 611 A1 was mixed with 20% by mass of fine CaCO ₃ with a grain size of <200 μm and dried in a contact dryer from List AG at 80 ° C. and 60 mbar. After a drying time of 40 min. only large, hard lumps preserved ( Fig. 3).

2. Examples of Invention (Drying Trials)

Aqueous dispersant solutions prepared according to DE 195 13 126 and DE 199 26 611 A1 were in each case without [A; B] and with drying aids (auxiliary polymer HP) [A1, A2, B1, B2] by means of a metering pump into a laboratory spray dryer from LabPlant and sprayed in a hot air stream. The inlet temperature was 180 ° C, the outlet temperature of the dry air was 50 to 70 ° C. Polymers HP1 and HP2 of the following composition were used as drying aids HP: HP1 maleic anhydride 36.8 mass% 2-acrylamido-2-methyl-propanesulfonic acid (AMPS) 38.8 mass% hydroxypropyl acrylate 24.4 mass% acrylic acid 29.0 mass% hydroxypropyl acrylate 58.3 mass% Na-methallyl 12.7 mass%

They were manufactured using the following processes:

HP1

In a reaction vessel equipped with a reflux condenser, stirrer, The thermometer, dropping funnel and nitrogen gas were placed in 530 g of water 98 g maleic anhydride, 103.5 g 2-acrylamido-2- methylpropanesulfonic acid (AMPS) and 65.1 g hydroxypropyl acrylate dissolved. The reaction solution was brought to 60 ° C. in a water bath while supplying nitrogen warmed and 4.3 g of ammonium peroxodisulfate and 8.5 g of mercaptoethanol added dropwise in 20 g of water. The reaction mixture was for 2 hours stirred at 70 ° C under nitrogen, then cooled to room temperature and neutralized to pH 7.0 with sodium hydroxide solution. The resulting product was a clear polymer solution with a solids content of 40 wt .-% and a molecular weight Mw ~ 5000.

HP2

According to the procedure for HP1, a Nitrogen atmosphere in 380 g water 46 g acrylic acid, 92.2 g Hydroxypropyl acrylate and 20 g sodium methallylsulfonic acid dissolved. The solution was then treated with 55 g of a 50% sodium hydroxide Solution neutralized. The reaction solution was then supplied with nitrogen heated to 55 ° C in a water bath and the polymerization by adding 20 g of a 20% aqueous ammonium persulfate solution started. The The reaction was stirred at 60 ° C under nitrogen for 4 hours. The The result was a clear polymer solution with a solids content of 45% by weight. and a molecular weight Mw ~ 7000.

The results of the spray drying are shown in Table 3 below. The designation HP stands for the content of the respective auxiliary polymer, expressed in% by mass based on the solids content of the polymer solution to be dried. Table 3

Figure No. 4 shows the powdery dispersant of test B1 after spray drying.

3. Examples of use

• - A: wässrige Lösung eines polymeren Dispergiermittels (PDM1) gemäß DE 195 13 126
• - B: wässrige Lösung eines polymeren Dispergiermittels (PDM2) gemäß DE 199 26 611 A1
• - A1 sprühgetrocknetes Pulver nach Zusatz von 10 Massen-% HP1 zur wässrigen Lösung des PDM1
• - A2: sprühgetrocknetes Pulver nach Zusatz von 15 Massen-% HP2 zur wässrigen Lösung des PDM1
• - B1: sprühgetrocknetes Pulver nach Zusatz von 10 Massen-% HP1 zur wässrigen Lösung des PDM2
• - B2: sprühgetrocknetes Pulver nach Zusatz von 15 Massen-% HP2 zur wässrigen Lösung des PDM2.

The following examples explain the flowability and physical properties of cement systems. In comparison, aqueous polymer solutions (A; B) were used as dispersants, and pulverulent dispersants were used which had been spray-dried using drying aids (HP) (A1, A2 or B1, B2):

• - A: aqueous solution of a polymeric dispersant (PDM1) according to DE 195 13 126
• - B: aqueous solution of a polymeric dispersant (PDM2) according to DE 199 26 611 A1
• - A1 spray-dried powder after adding 10% by mass of HP1 to the aqueous solution of the PDM1
• - A2: spray-dried powder after adding 15% by mass of HP2 to the aqueous solution of the PDM1
• - B1: spray-dried powder after adding 10% by mass of HP1 to the aqueous solution of the PDM2
• - B2: spray-dried powder after adding 15% by mass of HP2 to the aqueous solution of the PDM2.

The following mixture was selected as the standard formulation:
Mass [g] Portland cement (CEM I 42.5 R) 900.00 Standard quartz sand (0-2 mm, EN 196-1) 1350.00 Defoamer (Agitan P 800) 00:45 dispersants 0.2 (A, B series) or 0.3 (1.1; 1.2)% by weight mixing water 288 g

Mixed regulation and methods of determination

The mortar mixtures were prepared in accordance with DIN EN 196-1, Section 6.3. The flow behavior was determined using a flow channel test according to the Grouting mortar guideline of the German concrete association eV (version from September 1990, editorially revised 1996) after 5, 30 and 60 respectively Minutes determined.

The mortars were used to determine the compressive strengths Prisms with the dimensions 4 × 4 × 16 cm manufactured, these at the latest Switched off for 24 hours and then in a standard climate (+ 20 ° C and 65% relative Moisture) for further curing.

The determined flow channel values are summarized in Table 4, while in Table 5 the compressive strengths of the respective mortar mixtures are shown at different times. Table 4 Channel dimensions of the mortar mixtures

Table 5 Fresh mortar bulk density and compressive strength of the mortar prisms

Claims (23)

1. Use of water-soluble polymers consisting of a) monoethylenically unsaturated, acid group-bearing monomers in acid, partially or completely neutralized form of the series acrylic acid, methacrylic acid, 2-ethylacrylic acid, 2-propylacrylic acid, vinyl acetic acid, croton- and isocrotonic acid, maleic acid, fumaric acid, itaconic acid, citraconic acid, vinyl sulfonic acid, methallylsulfonic acid -Acrylamido-2-methylpropylsulfonic acid, 4-vinylphenylsulfonic acid, vinylphosphonic acid, (semi-) esters and / or amides of the carboxylic acids mentioned and their mixtures and / or their anhydrides and b) further monomers copolymerizable with the monomers a) from the series (meth) acrylamide, (meth) acrylonitrile, (meth) allyl alcohol, hydroxyalkyl (meth) acrylate, with alkyl = C ₁ to C ₅ , hydroxyalkylpolyethyleneoxy and propyleneoxy or -butyleneoxy (meth) - acrylate with alkyl = C ₁ to C ₅ , vinyl ethers such as. B. hydroxy and alkoxypolyethyleneoxy or polypropyleneoxyvinyl ether and analog allyl ethers with up to 10 repeating units, N-vinyl acetamide, N-vinyl lactams, N-vinyl pyrrolidone, N-vinyl imidazole, silicon-functional comonomers, such as (meth) acryloxyalkyltri- (alkoxy ) -Silanes, Vinyltrialkoxysilane and Vinylmethyldialkoxysilane with C ₁ to C ₅ alkyl or alkoxy radicals and their derivatives and mixtures thereof as drying aids for the production of redispersion powders and / or powdery, polymeric dispersants. 2. Use according to claim 1, characterized in that the water-soluble polymers at least 20% by weight of monomers a) and contain at most 80% by weight of monomers b). 3. Use according to one of claims 1 or 2, characterized characterized that the acid groups of the monoethylenic unsaturated monomers a) before, during or after Polymerization were at least partially neutralized, especially with the help of alkali and / or alkaline earth metal hydroxides, ammonia, a Amine, polyamine or amino alcohol. 4. Use according to one of claims 1 to 3, characterized in that the water-soluble polymer has an average molecular weight M _n of 1000 to 100,000 g / mol, preferably between 2000 and 70,000 g / mol and particularly preferably between 3000 and 50,000 g / mol. 5. Use according to one of claims 1 to 4, characterized characterized in that the water-soluble polymer by in particular radical polymerization in water or a hydrous Mixture with a maximum of 30 wt .-% of an organic solvent Emulsion polymerization or by a solvent-free Bulk polymerization was obtained. 6. Use according to any one of claims 1 to 5, characterized characterized in that as drying aids aqueous solutions, containing 1 to 99 wt .-% of the water-soluble polymer, especially preferably 20 to 70% by weight and very particularly preferably between 35 and 60 wt .-%, are used. 7. Use according to one of claims 1 to 6, characterized characterized in that the drying aid to the Manufacturing process in proportions up to a maximum of 50% by weight and preferably between 5 and 30 wt .-%, based on the Dispersant or the polymer dispersion is supplied. 8. Use according to one of claims 1 to 7, characterized characterized that the drying aid in one Spray drying process is used. 9. Use according to one of claims 1 to 7, characterized characterized that the drying aid in one Contact dryer, fluid bed dryer, belt dryer or in one Drying process is used with the help of heat radiation such as B. infrared or microwave radiation is carried out. 10. Use according to one of claims 1 to 9, characterized characterized in that the water-soluble polymer for manufacturing a dispersant is used which consists of Structural elements containing polyoxyalkylene, carboxylic acid and / or Carboxylic anhydride monomers, especially as from WO 97/39037, EP-PS 0610699 or WO 98/28353 known. 11. Use according to one of claims 1 to 10, characterized characterized in that a powdery polymeric dispersant is obtained that a residual moisture <5 wt .-% and preferably <2% by weight. 12. Use according to one of claims 1 to 11, characterized marked that with the drying aid produced polymeric dispersant quality-improving Additives from the group chalk, silica, calcite, dolomite, Quartz powder, bentonite, pumice powder, titanium dioxide, aluminum oxide, Fly ash, cements, silicate, talc, mica, anhydrite, lime, Diatomaceous earth, gypsum, magnesite, clay, kaolin, slate and Rock powder, barium sulfate and mixtures thereof added become. 13. Use according to claim 12, characterized in that the quality-improving additives in finely divided form, preferably with a particle size of 0.1 to 1000 microns can be used. 14. Use according to one of claims 1 to 13, characterized characterized in that the polymeric dispersant obtained mineral building materials in proportions of 0.05 to 5% by weight, based on the setting basic system. 15. Use according to one of claims 1 to 14, characterized characterized in that the polymeric dispersant obtained mineral systems, such as bitumen-containing building materials hydraulically setting binders, such as cement, or on latent hydraulically setting binders based building materials, gypsum, Anhydrite or other calcium sulfate-based building materials, ceramic masses, refractory masses, oilfield building materials and dispersion-based building materials. 16. Use according to one of claims 1 to 9, characterized characterized in that the drying aid of an aqueous Dispersion of a redispersible organic binder consisting of a base polymer from the group of vinyl ester, Styrene, acrylate, vinyl chloride or polyurethane polymers is added. 17. Use according to claim 16, characterized in that the aqueous dispersion of a redispersible organic binder additionally and in each case based on the base polymer a) up to 30% by mass of a cement plasticizer and / or b) up to 30% by mass of a protective colloid such as e.g. B. polyvinyl alcohol and / or c) up to 2% by mass of at least one surface-active substance such as emulsifiers or wetting agents and / or d) up to 3% by mass of a thickener such as polyacrylic acid and / or e) up to 2% by mass of a defoamer contains. 18. Use according to one of claims 1 to 9 and 16 or 17, characterized in that the redispersion powder prepared with the drying agent a) 1 to 30 wt .-%, based on the total weight of polymer components, of fine antiblocking agent such as finely ground aluminum silicates, diatomaceous earth, colloidal silica gel, pyrogenic silica, precipitated silica, microsilica, kaolin, talc, cements, diatomaceous earth, calcium and / or Magnesium carbonate and magnesium hydrosilicate and b) 0.1 to 10% by weight, based on the base polymer, of further additives are admixed. 19. Use according to any one of claims 1 to 9 and 16 to 18, characterized characterized in that the redispension powder obtained in mineral-setting building materials and in tile adhesives, Leveling compounds, gypsum building materials, lime mortars, cement mortars, plasters and dry mortars are used. 20. Use according to one of claims 1 to 9 and 16 to 18, characterized characterized in that the redispension powder obtained in Adhesive compositions and paints are used. 21. Use according to one of claims 1 to 9 and 16 to 18, characterized characterized that the redispension powder obtained as Sole binders can be used for coating agents. 22. Redispersible powder can be produced according to one of the Claims 1 to 9 and 16 to 18. 23. Containing building material composition 10 to 60% by weight of a mineral binder, 0.1 to 20% by weight of a polymer powder prepared with the drying aid according to one of claims 1 to 9, - Up to 25 wt .-% of conventional auxiliaries, each based on the total composition and - as a residual quantity, additives such as sand, fillers, pigments, natural fibers and / or synthetic fibers.