Aqueous stabilizer composition, aqueous dispersion, and use and production method thereof

Abstract

The present invention relates to aqueous stabilizer compositions, aqueous dispersions and uses thereof, and uses and methods of production thereof. The aqueous stabilizer composition is an aqueous composition, in particular a solution or dispersion, for stabilizing a dispersion comprising a compound having a solubility in water at 20 DEG C in the range of 0.05 to 10 g / l, said composition comprising at least one thickening agent and at least one wetting or dispersing agent.

Description

Technical Field

[0001] The invention relates to the technical field of coatings, in particular to semi-finished products and pigment pastes used for coatings.

[0002] In particular, the present invention relates to an aqueous composition for stabilizing dispersions.

[0003] Furthermore, the invention relates to the use of the aqueous composition for stabilizing dispersions and to the corresponding stable dispersions, in particular semi-finished products.

[0004] Finally, the invention relates to a process for producing an aqueous composition for stabilizing dispersions. Background Art

[0005] Modern coating systems, especially paints, are increasingly formulated on a water-based basis, since they should be as free of volatile organic compounds (VOC) as possible. Such VOC-free paint systems or systems with a VOC content of less than 1 g / l are considered solvent-free and emission-free. From the perspective of environmental protection and health protection, they do not cause problems, or at least cause fewer problems than solvent-based systems.

[0006] Furthermore, efforts are being made to avoid the use of preservatives and biocides in paints, or at least to reduce their use. If the paint system does not contain any preservatives or biocides, then generally no hazardous substances need to be declared and the paint can be used and processed without any occupational safety issues and without any special safety precautions.

[0007] In practice, the use of aqueous systems, in particular in combination with organic binder systems, often leads to rapid infection of the coating with microorganisms, in particular bacteria, yeasts or even molds, so that preservatives and / or biocides usually have to be added to the coating. This applies in particular to aqueous pigment pastes, which are used in particular for tinting systems. Tinting systems are often used to provide a variety of different colors and shades, which can be selected and combined individually by the customer. Tinting systems usually consist of a set of colored pigment pastes, which are mixed with a binder or a binder mixture, i.e. a so-called tinting base or base composition, to obtain a paint, in particular a wall paint, with the desired hue. Pigment pastes are highly concentrated pigment-containing dispersions. The pigment paste and the base or tinting base are then mixed together to produce a ready-to-use colorant or coating.

[0008] The mixing of different quantities of the individual pigment pastes with the tinting base is carried out in the machine, where the mixing process is carried out with the support of software. After being removed from the original container, the pigment pastes are stored in a more or less open state for several weeks, during which time they are exposed to microorganisms, especially bacteria, yeasts and mold spores, via the surrounding air, which almost inevitably leads to infestation of solvent-free or water-based systems with bacteria, yeasts or molds.

[0009] Therefore, preservatives and biocides are used almost exclusively in aqueous pigment pastes and tinting systems. However, the use of biocides and preservatives is disadvantageous for a number of reasons, since biocides and preservatives generally represent substances that are problematic for health and environmental protection, their use should be minimized, and their use is increasingly regulated by strict chemical regulations. In addition, a serious disadvantage of conventional organic biocides is their vapor pressure: the biocides are converted into the gas phase and may, for example, cause allergies, wherein, in particular, there is the risk of biocides accumulating in indoor air. In addition, organic biocides are generally not stable over the long term and, for example, may be decomposed by UV radiation.

[0010] Therefore, attempts have been made to provide aqueous pigment pastes, in particular for tinting systems, without preservatives or biocides. For this purpose, the pH of the pigment paste is usually set to 10 or higher, thereby creating an environment in which many bacteria and yeasts, as well as most fungi, cannot grow.

[0011] However, it has been demonstrated that there are a large number of alkaliphilic bacteria, yeasts and fungi, especially molds, which either grow well under these alkaline conditions or are able to successfully adapt to these conditions. To combat these alkaliphilic microorganisms, preservatives and biocides must be used.

[0012] In addition, calcium aluminate sulfate (which contains the empirical formula Ca 6 Al 2 [(OH) 12 (SO 4 ) 3 ]·26H 2 The mineral calcium aluminate (calcium sulfate) can be used as a white pigment in paints and paper coatings. Calcium aluminate is sold in the form of an aqueous alkaline suspension and can be added in small quantities, in particular to paints. A method for producing a precipitate based on calcium aluminate is described in WO 97 / 35807A1. It is not possible to use a large amount of calcium aluminate in an adhesive system because the relatively good solubility of calcium aluminate in water and the amount of divalent and trivalent ions produced in the dispersion can cause the adhesive system to thicken rapidly. In particular, coagulation of dispersed components (in particular electrostatically stabilized components) is observed. However, the divalent and trivalent ions present in the solution, in particular aluminum ions, also give the aqueous suspension of calcium aluminate a microbial resistance effect that exceeds the alkaline pH value, that is, the aqueous suspension of calcium aluminate is difficult to be infected or colonized by various organisms, in particular bacteria, yeasts or molds.

[0013] However, another disadvantage of calcium aluminate sulfate is that it has poor dispersion stability and dries quickly when processed into paint, that is, the open time of the paint is very short.

[0014] EP 4 183 842 A1 describes a composition, in particular a pigment paste, in which calcium aluminate sulfate can be dispersed in a long-term stable manner in amounts of up to 20% by weight. These pigment preparations are also very suitable for incorporation into coating systems, in particular paints and varnishes, which, by using a pigment paste, can be permanently protected from microbial contamination even without the use of biocides.

[0015] However, the use of calcium aluminate sulfate, in particular ettringite, and other compounds with a solubility of about 1 g / l is problematic, since substances with such residual solubility undergo so-called Ostwald ripening. On the one hand, this means that large crystals or particles grow at the expense of smaller crystals or particles, which means that even stable dispersions become unstable during storage; the larger crystals that form tend to precipitate more severely. In addition, the contacting crystals grow together at the interface, so that the precipitate becomes hard and cannot even be redispersed by conventional mechanical methods (such as stirring), especially with an indeterminate particle size. These properties are particularly problematic for the use of pigment pastes or coatings, since particles of a defined particle size and a defined amount must be present in the dispersion in order to achieve a uniform color appearance and uniform color properties. Although pigment pastes or coatings containing calcium aluminate sulfate or similar substances with a relatively high residual solubility can be stable for a long time because they contain relatively small proportions of these problematic compounds, this is difficult to achieve for primary products (especially semi-finished products) for the production of pigment pastes or coating systems, since these products contain large amounts of calcium aluminate sulfate or similar substances. In particular, calcium aluminate sulfate dispersions tend to settle and must be constantly stirred to prevent the formation of hard deposits.

[0016] The strong tendency to settle can also cause problems for continued production, since crusts form in the lower part of the supply lines and the lines become blocked due to further crystal growth and accumulation of particles.

[0017] Initial products and in particular semi-finished products containing calcium aluminate sulfate must be constantly stirred or at least discharged regularly. Delivery to the production site must be carried out close to the production site, which requires high logistics and storage costs, because without stirring, the quality of the dispersion deteriorates rapidly: precipitation quickly occurs and irreversible deposits are formed. This applies to all production applications of aqueous preparations of calcium aluminate sulfate and, in general, to compounds with a relatively high residual solubility in water-based suspensions.

[0018] This problematic behavior also prevents the use of calcium aluminum sulfate or similar compounds (such as hydrated calcium silicate) in other technical fields, in particular in cosmetic preparations, disinfectants or pharmaceutical preparations, which are in principle suitable for use as pigments, carriers or the like.

[0019] Dispersions of solids in liquids can usually be stabilized using wetting agents or dispersants. However, this type of stabilization is only possible to a limited extent for compounds with high residual solubility, since there is a dynamic equilibrium between the particle surface and the dissolved ions. Conventional wetting agents cannot produce an effect or can only produce a limited effect, since the particle interface is thermodynamically unstable. In particular, electrostatic stabilization is not possible or is possible only to a very limited extent due to these dynamic processes.

[0020] Thickeners are known to delay the creation of solid deposits by slowing down the settling and diffusion of ions, but they cannot stop the process.

[0021] In addition, the disadvantage of using thickeners is that the thickened solution is difficult to process due to its high viscosity, and low viscosity dispersions are used as much as possible during the production process, especially if the dispersion is transported using a pump. In addition, the substantial increase in viscosity also leads to severe restrictions on product applications, because many applications require or require low viscosity, such as paints and varnishes. In particular, many thickeners use gel formation to cause a strong thickening of the dispersion, which makes the dispersion unsuitable for many applications. In addition, the presence of divalent and trivalent metal ions (which usually appear in high concentrations in dispersions of compounds with high residual solubility) usually causes rapid gel formation in combination with thickeners, which in turn makes the product unsuitable for a wide range of applications.

[0022] Therefore, the prior art still lacks a composition or method capable of stabilizing a dispersion of a compound having a solubility in water of about 1 g / l to 10 g / l at 20°C.

[0023] In particular, it is not known from the prior art how to permanently stabilize highly filled dispersions comprising a high proportion of compounds having a high residual solubility without the formation of solid deposits. Summary of the invention

[0024] It is therefore an object of the present invention to provide a system which avoids or at least alleviates the above-mentioned disadvantages and problems associated with the prior art.

[0025] In particular, it was an object of the present invention to provide a system which enables high concentrations of compounds having a high residual solubility to be dispersed stably over a long period of time.

[0026] Another object of the present invention is to provide a system which is able to stabilize dispersions comprising high concentrations of compounds having high residual solubility, wherein the dispersions retain a low viscosity.

[0027] Another object of the present invention is to provide low-viscosity, long-term stable dispersions of compounds having high residual solubility.

[0028] Thus, according to a first aspect of the invention, the subject of the invention is an aqueous composition, in particular a solution or dispersion, for stabilizing a dispersion comprising a compound having a solubility in water in the range of 0.05 to 10 g / l at 20° C., wherein the composition comprises

[0029] (a) at least one thickener and

[0030] (b) at least one wetting agent or dispersant.

[0031] According to a second aspect of the invention, a further subject of the invention is the use of the aforementioned aqueous composition for stabilizing an aqueous dispersion comprising at least one compound having a solubility in water at 20° C. in the range from 0.05 to 10 g / l, in particular from 0.05 to 5 g / l, preferably from 0.1 to 4 g / l, more preferably from 0.2 to 3 g / l, particularly preferably from 0.2 to 2 g / l, even more preferably from 0.3 to 1.5 g / l, particularly preferably from 0.4 to 1 g / l.

[0032] According to a third aspect of the invention, another subject of the invention is an aqueous dispersion, in particular a semi-finished product, comprising

[0033] (i) at least one compound having a solubility in water at 20° C. in the range of 0.05 to 5 g / l,

[0034] (ii) at least one thickener and

[0035] (iii) at least one wetting agent or dispersant.

[0036] According to a fourth aspect of the invention, a further subject of the invention is a process for producing the above-mentioned aqueous dispersion, wherein a dispersion comprising at least one compound having a solubility in water in the range of 0.05 to 10 g / l at 20° C. is provided and an aqueous composition is added. BRIEF DESCRIPTION OF THE DRAWINGS

[0037] The following figures show

[0038] Figure 1 : Sedimentation curve of commercially available calcium aluminate sulfate suspension;

[0039] Figure 2 : Stability index of commercially available calcium aluminate sulfate suspension at t = 500 s;

[0040] Figure 3 : Comparison of the stability index of a commercially available calcium aluminate sulfate suspension and a calcium aluminate sulfate suspension stabilized according to the present invention at t=500s;

[0041] Figure 4: Comparison of the stability index as a function of time of a commercially available calcium aluminate sulphate suspension and a calcium aluminate sulphate suspension stabilized according to the invention;

[0042] Figure 5 : Stability index at t=500 s of a commercial calcium aluminate sulphate suspension, a calcium aluminate sulphate suspension stabilised according to the invention and a comparative suspension comprising only one thickener in addition to calcium aluminate;

[0043] Figure 6 : Comparison of the stability index of a commercial calcium silicate hydrate suspension and a calcium silicate hydrate suspension stabilized according to the present invention at t=500s; and

[0044] Figure 7 : Comparison of the stability index as a function of time of commercially available calcium silicate hydrate suspensions and a calcium silicate hydrate suspension stabilized according to the invention. DETAILED DESCRIPTION

[0045] It goes without saying that in order to avoid unnecessary repetition, the specific features, characteristics, configurations, implementation modes and advantages described below for only one aspect of the present invention naturally also apply to other aspects of the present invention without explicit mention.

[0046] Furthermore, it should be noted that for all relative or percentages given below, in particular weight-related amounts, these amounts should be selected by the person skilled in the art so that the sum of the components, additives or auxiliary substances etc. always amounts to 100% or 100% by weight. However, this is self-evident for the person skilled in the art.

[0047] Furthermore, all parameter values ​​and the like mentioned below can be measured or determined using standardized or explicitly stated assay methods or using assay methods familiar to those skilled in the art.

[0048] On this premise, the subject matter of the invention is explained in more detail below.

[0049] Thus, according to a first aspect of the invention, the subject of the invention is an aqueous composition, in particular a solution or dispersion, for stabilizing a dispersion comprising a compound having a solubility in water in the range of 0.05 to 10 g / l at 20° C., wherein the composition comprises

[0050] (a) at least one thickener, and

[0051] (b) at least one wetting agent or dispersant.

[0052] Preferably, an aqueous composition, in particular a solution or dispersion, for stabilizing a dispersion comprising a compound having a solubility in water in the range of 0.05 to 10 g / l at 20° C. consists of at least one thickener, at least one wetting agent or dispersant and water.

[0053] By using solutions or dispersions comprising thickeners and wetting agents or dispersants, dispersions of compounds with high residual solubility, in particular dispersions of compounds with a solubility in water in the range of 0.05 to 10 g / l at 20° C., can be dispersed stably over a long period of time. Surprisingly, this can also be achieved if the dispersion comprises the compound with high residual solubility in a high proportion, for example 70 or 80% by weight, based on the dispersion.

[0054] Furthermore, by means of the combination of thickeners and wetting agents or dispersants according to the invention, stable low-viscosity dispersions of compounds with high residual solubility can be obtained, whereby the dispersions can be industrially processed and supplied for a wide variety of applications.

[0055] In the context of the present invention, a solution is understood to be a single-phase system, usually liquid, in which at least one substance, in particular a compound or its building blocks, such as an ion, is uniformly distributed in another substance, the so-called solvent. In the context of the present invention, a dispersion is understood to be an at least two-phase system, in which a first phase, the dispersed phase, is distributed in a second phase, the continuous phase. The continuous phase is also referred to as dispersion medium or dispersant; in the context of the present invention, the continuous phase is usually in liquid form, so that in the context of the present invention, a dispersion is usually a solid-liquid dispersion. Compounds whose solubility in water at 20° C. is in the range from 0.05 to 10 g / l are usually the dispersed phase or one of the dispersed phases within the scope of the present invention.

[0056] Surprisingly, the process according to the invention also makes it possible to suppress Ostwald ripening, so that once the particle size has been determined, it also remains stable in the dispersion for a long time, in particular for several months, and without the formation of solid and non-redispersible precipitates in the storage container. In the present invention, the gel formation usually observed when thickeners are used alone can also be effectively avoided, so that the viscosity of the dispersion can be kept within an acceptable range for many applications. This is particularly surprising since high concentrations of divalent and trivalent metal ions in the presence of thickeners usually contribute to gel formation.

[0057] The compositions according to the invention are particularly suitable for stabilizing pastes, paints, varnishes, glazes, papermaking, cosmetic preparations, pharmaceutical preparations, liquid semi-finished products and raw materials for industrial processes, detergents and cleaning agents, impregnation agents and disinfectants and dispersions in the field of surface treatment technology.

[0058] In the context of the present invention, particularly good results are achieved if the dispersion to be stabilized contains compounds whose solubility in water at 20° C. is less than 10 g / l, in particular less than 4 g / l, preferably less than 3 g / l, more preferably less than 2 g / l, particularly preferably less than 1.5 g / l and even more preferably less than 1 g / l.

[0059] Similarly, particularly good results are achieved if the dispersion to be stabilized comprises compounds having a solubility in water at 20° C. of more than 0.1 g / l, in particular more than 0.2 g / l, preferably more than 0.3 g / l, more preferably more than 0.4 g / l.

[0060] Furthermore, it is sufficient in the context of the present invention if the dispersion to be stabilized comprises compounds whose solubility in water at 20° C. is in the range from 0.05 to 5 g / l, in particular from 0.1 to 4 g / l, preferably from 0.2 to 3 g / l, more preferably from 0.2 to 2 g / l, particularly preferably from 0.3 to 1.5 g / l and even more preferably from 0.4 to 1 g / l.

[0061] Compounds with the above-mentioned relatively high solubility (also called residual solubility) are in principle poorly soluble and can be provided in the form of aqueous dispersions. However, due to the pronounced and non-negligible solubility and the associated high ion concentration in the liquid phase, these dispersions give rise to numerous problems during production and use. One of the main problems is the above-mentioned Ostwald ripening, which is due to the fact that the compounds are subject to dynamic dissolution and sedimentation processes, whereby the particle size shifts towards larger particles, which in turn leads to a greater tendency to sediment and changes the properties of the dispersions and the pigment pastes and colorants containing them. In addition, these dynamic processes can also lead to the formation of agglomerates and ultimately to the production of compact deposits that cannot be redispersed even using conventional mechanical methods.

[0062] Furthermore, the presence of high concentrations of metal ions, in particular divalent and trivalent metal ions, also generally leads to gel formation by reaction with the binder system or rheological additives, in particular thickeners. However, in the context of the present invention, these negative effects can be avoided.

[0063] In the context of the present invention, the compound having a solubility in water at 20° C. in the range of 0.05 to 10 g / l is generally selected from the group consisting of magnesium aluminum phosphate, magnesium aluminum silicate, calcium aluminum phosphate, calcium aluminum silicate, calcium aluminate hydrate, calcium aluminate sulfate, calcium sulfate, calcium hydroxide, calcium silicate hydrate, ammonium trifluoromanganate (NH 4 Mn 3 ), sodium trifluoromanganate (NaMnF 3 ), manganese (II) fluoride, sodium fluoride and mixtures thereof.

[0064] In the context of the present invention, if the compound with a solubility in water at 20° C. in the range of 0.05 to 10 g / l is selected from calcium aluminate hydrate, calcium aluminate sulfate, calcium sulfate, calcium hydroxide, calcium silicate hydrate, ammonium trifluoromanganate (NH 4 Mn 3 ), sodium trifluoromanganate (NaMnF 3), manganese (II) fluoride, sodium fluoride and mixtures thereof, particularly good results can be obtained.

[0065] In the context of the present invention, if the compound having a solubility in water at 20° C. in the range of 0.05 to 10 g / l is selected from the group consisting of: tricalcium aluminate hydrate [respectively 3CaO*Al 2 O 3 *6H 2 O,Ca 3 Al 2 (OH) 12 ], tetracalcium aluminate hydrate [4CaO*Al 2 O 3 *7H 2 O,Ca 4 Al 2 (OH) 14 ], calcium aluminate sulfate [ettringite, respectively 3CaO*Al 2 O 3 *3CaSO 4 *32H 2 O,Ca 6 [Al(OH) 6 ] 2 (SO 4 ) 2 *26H 2 O], calcium sulfate, calcium hydroxide, hydrated calcium silicate [Ca 6 Si 6 O 18 *H 2 O], ammonium trifluoromanganate (NH 4 Mn 3 ), sodium trifluoromanganate (NaMnF 3 ), manganese(II) fluoride, sodium fluoride and mixtures thereof. In this context, particularly good results are obtained if the compound having a solubility in water at 20° C. in the range of 0.05 to 10 g / l is selected from the group consisting of tetracalcium aluminate hydrate, calcium aluminate sulfate, calcium silicate hydrate and mixtures thereof, preferably calcium aluminate sulfate, calcium silicate hydrate and mixtures thereof.

[0066] In the context of the present invention, if the compound having a solubility in water at 20° C. in the range of 0.05 to 5 g / l is calcium aluminum sulfate [ettringite, respectively 3CaO*Al 2 O 3 *3CaSO 4 *32H 2 O,Ca 6 [Al(OH) 6 ] 2 (SO 4 ) 2*26H 2 Sometimes, the molecular formula is expressed as 24 crystal water molecules, which is different from the expression of 26 crystal water molecules shown above. However, it always refers to the same compound.

[0067] Calcium aluminum sulfate is sold on the market in the form of an aqueous suspension. Calcium aluminum sulfate consists of the mineral ettringite and contains a calcium oxide content of about 13.5% by weight, an aluminum oxide content of about 8% by weight and about 45% by weight of water of crystallization. Calcium aluminum sulfate or ettringite or its aqueous dispersion is sometimes also used as a white pigment in architectural paints and paper coatings. Calcium aluminum sulfate has a high covering power as well as strong settling properties and a fast drying behavior and therefore cannot usually be used in aqueous dispersions, especially in paints, in high concentrations, and processing into coatings has become a problem.

[0068] In the context of the present invention, compounds having a solubility in water at 20° C. in the range from 0.05 to 10 g / l are generally present in particulate form.

[0069] In the context of the present invention, according to one embodiment, it can be provided that the compound having a solubility in water at 20° C. in the range of 0.05 to 10 g / l has a particle size distribution D10 in the range of 0.05 to 0.5 μm, in particular 0.1 to 0.4 μm, preferably 0.15 to 0.3 μm, more preferably 0.18 to 0.25 μm.

[0070] Similarly, it is envisaged that compounds having a solubility in water at 20°C in the range of 0.05 to 5 g / l comprise a particle size distribution D50 in the range of 1.0 to 4 μm, in particular 1.5 to 3.0 μm, preferably 1.8 to 2.7 μm, more preferably 2.0 to 2.5 μm.

[0071] It can also be provided that the compound having a solubility in water at 20° C. in the range of 0.05 to 10 g / l comprises a particle size distribution D90 in the range of 5.0 to 10 μm, in particular 5.5 to 8.0 μm, preferably 6.0 to 7.5 μm, more preferably 6.5 to 7.0 μm.

[0072] The terms D10, D50 and D90 mean that 10% of all particles, or 50% of all particles or 90% of all particles, respectively, have a smaller particle size.The particle size or the particle size distribution can be determined in particular by laser scattering.

[0073] According to a particularly preferred embodiment of the present invention, the compound having a solubility in water at 20° C. in the range of 0.05 to 10 g / l has a particle size distribution D10 in the range of 0.05 to 0.45 μm, in particular 0.1 to 0.4 μm, preferably 0.15 to 0.3 μm, more preferably 0.18 to 0.25 μm.

[0074] Likewise, according to this embodiment, it can be provided that the compound having a solubility in water at 20° C. in the range of 0.05 to 10 g / l comprises a particle size distribution D50 in the range of 0.5 to 1.8 μm, in particular 0.6 to 1.5 μm, preferably 0.7 to 1.2 μm, more preferably 0.8 to 1.0 μm.

[0075] Furthermore, according to this embodiment, it can be provided that the compound having a solubility in water at 20° C. in the range of 0.05 to 10 g / l comprises a particle size distribution D90 in the range of 2.0 to 4 μm, in particular 2.2 to 3.7 μm, preferably 2.5 to 3.5 μm, more preferably 2.8 to 3.2 μm.

[0076] Granules having the above-mentioned particle sizes are suitable in particular for pigment pastes and paints, but also for papermaking, cosmetic preparations, pharmaceutical preparations, liquid semi-finished products and raw materials for industrial processes, detergents and cleaning agents, impregnation and disinfecting agents and for surface treatment.

[0077] As for the thickener, it can be chosen from a large number of possible compounds within the scope of the present invention.

[0078] However, particularly good results are obtained in the context of the present invention if the thickener is selected from the group of polysaccharides, proteins, polyvinyl alcohol, silicic acids (silicic acid), silicates and mixtures thereof. In the context of the present invention, it is particularly preferred if the thickener is a polysaccharide.

[0079] According to a preferred embodiment of the invention, the thickener is selected from the group consisting of: xanthan gum, β-glucan, thiolated polysaccharides, proteoglycans, gum arabic, gum karaya, gum tragacanth, locust bean gum, guar gum, quince gum, pectin, agar, carrageenan, alginates, starch, starch derivatives, cellulose, cellulose derivatives, in particular cellulose ethers, silicic acids, bentonites, phyllosilicates, polyvinyl alcohol, gelatin, casein and mixtures thereof. Particularly good results are obtained in this case if the thickener is selected from the group consisting of xanthan gum, β-glucan, thiolated polysaccharides, proteoglycans, cellulose ethers, silicic acids, bentonites, phyllosilicates, polyvinyl alcohol, gelatin, casein and mixtures thereof. Within the scope of the invention, the best results are obtained if the thickener is a cellulose ether.

[0080] If the thickener is a cellulose ether, it proves particularly good if the thickener is selected from carboxymethylcellulose (CMC), methylcellulose (MC), ethylcellulose (EC), hydroxyethylcellulose (HEC), hydroxypropylcellulose (HPC), methylethylcellulose (MEC), hydroxyethylmethylcellulose (HEMC), hydroxypropylmethylcellulose (HPMC), ethylhydroxyethylcellulose and mixtures thereof.

[0081] As far as the wetting agent or dispersant in the aqueous composition according to the invention is concerned, it is usually selected from nonionic polymers, cationic polymers, anionic polymers and mixtures thereof, in particular nonionic polymers, anionic polymers, copolymers with pigment-affinity groups, polyethers and mixtures thereof. Therefore, a large number of surface-active substances can be used as wetting agents or dispersants. Wetting agents or dispersants with pigment-affinity groups are particularly preferred.

[0082] Particularly good results are obtained in the context of the present invention if the wetting agent or dispersant is selected from the group of polymers having pigment-affinic groups, silicone-modified polymers, block copolymers, graft copolymers, surfactants, modified natural oils and mixtures thereof.

[0083] Furthermore, it is adequate in the context of the present invention if the wetting or dispersing agent is selected from the group consisting of polycarboxylates, in particular salts of polyacrylic acids, polyphosphates, in particular linear polyphosphates and / or cyclic metaphosphates, polyether phosphates, polycarboxylic acid polymers, acrylic block copolymers, polyurethanes, ethoxylated fatty alcohols, nonionic saturated long-chain alcohols, fatty alcohol sulfates, alkyl phosphonates, silicone ethers, in particular methoxypolyethoxypropyl trisiloxanes, alkynyl ethoxylates, surfactants, gemini surfactants, bola surfactants, fluorosurfactants, modified natural oils and mixtures thereof.

[0084] Furthermore, it is well established if the wetting or dispersing agent is selected from the group consisting of salts of polyacrylic acids, polyphosphates, in particular linear polyphosphates and / or cyclic metaphosphates, polyether phosphates, polycarboxylic acid polymers, acrylic block copolymers, polyurethanes, ethoxylated fatty alcohols, nonionic saturated long-chain alcohols, fatty alcohol sulfates, alkylphosphonic acid esters, silicone ethers, in particular methoxypolyethoxypropyl trisiloxanes, alkynyl ethoxylates, gemini surfactants, bola surfactants, modified natural oils and mixtures thereof.

[0085] According to a preferred embodiment of the present invention, the wetting agent or dispersant is selected from the group consisting of sodium salts of polyacrylic acids, ammonium salts of polyacrylic acids, polyether phosphates, polycarboxylic acid polymers, modified styrene-maleic acid copolymers, polysiloxane ethers, in particular methoxypolyethoxypropyl trisiloxanes, gemini surfactants, bola surfactants, modified natural oils and mixtures thereof.

[0086] Best results are achieved within the scope of the present invention if the wetting agent or dispersant is a modified styrene-maleic acid copolymer.

[0087] Preferably, the polymer of the above-mentioned wetting agent or dispersant is functionalized, in particular acidic and / or basic functionalized. Preferably, the polymer comprises at least one functional group, which can be selected in particular from the following group: hydroxyl (-OH), thiol (-SH), amine, ammonium, carboxyl, carbonyl, ester, ether, sulfonyl, phosphonic acid, phosphoric acid and / or phosphate ester functional groups, preferably hydroxyl (-OH), thiol (-SH) and / or amine functional groups.

[0088] The molecular weight of the wetting or dispersing agent used can also vary within a wide range. Typically, the average molecular weight, in particular the weight average molecular weight, of the wetting or dispersing agent used is at least 1,000 g / mol, preferably at least 1,500 g / mol. Typically, the average molecular weight, in particular the weight average molecular weight, of the wetting or dispersing agent is in the range of 1,000 to 1,000,000 g / mol, in particular 1,250 to 100,000 g / mol, preferably 1,500 to 75,000 g / mol, particularly preferably 2,000 to 50,000 g / mol.

[0089] Advantageously, the wetting agent or dispersant is based on a functionalized polymer, in particular an acidic and / or basic functionalized polymer, in particular a polymer having polar functional groups. For example, the wetting agent or dispersant may be selected from the group consisting of functionalized polyamines, functionalized polyurethanes, functionalized poly(meth)acrylates, functionalized vinyl copolymers, functionalized polyether / polyester copolymers, functionalized polyethers, functionalized polyesters, functionalized fatty acid copolymers, functionalized block copolymers and / or functionalized polyalkoxylates and mixtures or combinations of at least two of these compounds.

[0090] The polymer of the above-mentioned wetting agent or dispersant is preferably acidic and / or basic functionalized. Preferably, the polymer comprises at least one functional group, which can be selected in particular from the following group: hydroxyl (-OH), sulfhydryl (-SH), amine, ammonium, carboxyl, carbonyl, ester, ether, sulfonyl, phosphonic acid, phosphoric acid and / or phosphate ester functional groups, preferably hydroxyl (-OH), sulfhydryl (-SH) and / or amine functional groups.

[0091] Preferably, the wetting agent or dispersant may be selected from the dispersants and / or wetting agents described in the following publications, the disclosures of each of which are hereby incorporated herein by reference:

[0092] – polyurethanes according to EP 0 154 678 A and EP 0 318 999 A;

[0093] - polyurethanes according to EP 0 270 126 A;

[0094] – modified polyurethanes and polyamines according to EP 1 593 700 A;

[0095] - salified polyamines according to EP 0 893 155 A;

[0096] - phosphoric acid esters according to EP 0 417 490 A;

[0097] - branched polymers comprising imidazole groups according to EP 1 081 169 A;

[0098] - ethoxylates, in particular alkoxylated epoxide / amine adducts according to EP 1 650 246 A and epoxy adducts according to EP 1 486 524 A;

[0099] - fatty acid copolymers according to EP 1 640 389 A;

[0100] – esterified polyacrylates according to EP 0 879 860 A;

[0101] - acid-functional polyesters according to WO 2005 / 097872 A;

[0102] - Block copolymers according to EP 1 416 019 A (gradient copolymers).

[0103] As described above, the combination according to the invention of a thickener on the one hand and a wetting agent or dispersant on the other hand allows stabilization of highly filled dispersions of compounds with high residual solubility, wherein in particular low-viscosity dispersions that are stable over a long period of time can be obtained.

[0104] In the context of the present invention, it has proven particularly effective if the compositions comprise thickener and wetting or dispersing agent in the specified ratios to one another.

[0105] Particularly good results are achieved if the weight-related ratio of thickener to wetting agent or dispersant of the composition (thickener:wetting agent or dispersant) is in the range from 2:1 to 1:20, in particular from 1:1 to 1:15, preferably from 1:1 to 1:10, more preferably from 1:2 to 1:8, particularly preferably from 1:3 to 1:5.

[0106] The aqueous composition according to the invention therefore preferably comprises significantly greater amounts of wetting agents or dispersants than thickeners. Nevertheless, the presence of thickeners is essential to prevent Ostwald ripening and to obtain dispersions with long-term stability.

[0107] As regards the amount of thickener the composition comprises, it has proven sufficient if the composition comprises up to 20% by weight, in particular up to 18% by weight, preferably up to 15% by weight, more preferably up to 12% by weight, based on the amount of the composition.

[0108] Similarly, it is conceivable that the composition comprises more than 1 wt. %, in particular more than 2 wt. %, preferably more than 5 wt. %, more preferably more than 8 wt. %, based on the amount of the composition, of thickener, which has been well established.

[0109] Furthermore, in the context of the present invention, it has proven sufficient if the composition comprises 1 to 20% by weight, in particular 2 to 18% by weight, preferably 5 to 15% by weight, more preferably 8 to 12% by weight, of thickener, based on the amount of the composition.

[0110] As regards the amount of wetting or dispersing agent which the composition comprises, this can naturally vary within wide ranges. However, it has proven sufficient if the composition comprises up to 65% by weight, in particular up to 60% by weight, preferably up to 55% by weight, more preferably up to 50% by weight, of wetting or dispersing agent, based on the amount of the composition.

[0111] Similarly, in the context of the present invention, it is conceivable that the composition comprises more than 20% by weight, in particular more than 25% by weight, preferably more than 30% by weight, more preferably more than 35% by weight, based on the amount of the composition, of a wetting agent or dispersant.

[0112] According to a preferred embodiment of the present invention, the composition comprises 20 to 65% by weight, in particular 25 to 60% by weight, preferably 30 to 55% by weight, more preferably 35 to 50% by weight of a wetting agent or dispersant, based on the amount of the composition.

[0113] Using thickeners and wetting and dispersing agents in the amounts indicated above, solutions or dispersions are obtained which are very suitable as additives for stabilizing dispersions comprising large amounts of compounds with a high residual solubility.

[0114] As mentioned above, the composition is an aqueous composition. In this case, it is sufficient if the composition comprises up to 79% by weight, in particular up to 78% by weight, preferably up to 63% by weight, more preferably up to 57% by weight of water, based on the amount of the composition.

[0115] Similarly, it can be provided that the composition comprises at least 15% by weight, in particular at least 30% by weight, preferably at least 38% by weight, of water, based on the amount of the composition.

[0116] Furthermore, it is conceivable within the context of the present invention that the composition comprises 15 to 79% by weight, in particular 30 to 78% by weight, preferably 30 to 63% by weight, preferably 38 to 57% by weight, of water, based on the amount of the composition.

[0117] According to a preferred embodiment of the present invention, the composition comprises

[0118] (a) at least one thickener, in particular in an amount of 1 to 20% by weight,

[0119] (b) at least one wetting agent or dispersant, in particular in an amount of 20 to 65% by weight, and

[0120] (c) Water, in particular in amounts of 15 to 79% by weight, based in each case on the composition.

[0121] For this particularly preferred embodiment of the invention, all of the above-mentioned parameters, features, advantages and special features apply correspondingly. According to another preferred embodiment of the invention, the composition comprises the above-mentioned components (a) to (c).

[0122] According to a second aspect of the invention, another subject of the invention is the use of the aforementioned aqueous composition for stabilizing an aqueous dispersion comprising at least one compound having a solubility in water at 20° C. in the range from 0.05 to 10 g / l, in particular from 0.05 to 5 g / l, preferably from 0.1 to 4 g / l, more preferably from 0.2 to 3 g / l, even more preferably from 0.2 to 2 g / l, most preferably from 0.3 to 1.5 g / l, particularly preferably from 0.4 to 1 g / l.

[0123] For further details on the use according to the invention, reference is made to the above-described configurations of the aqueous composition according to the invention, which apply correspondingly to the use according to the invention.

[0124] According to a third aspect of the invention, another subject of the invention is an aqueous dispersion, in particular a semi-finished product, comprising

[0125] (i) at least one compound having a solubility in water at 20° C. in the range of 0.05 to 10 g / l,

[0126] (ii) at least one thickener and

[0127] (iii) at least one wetting agent or dispersant.

[0128] The aqueous dispersion according to the invention is obtained in particular by adding a compound having a solubility in water in the range of 0.05 to 10 g / l at 20° C. to the above-described aqueous composition or by adding the above-described aqueous composition to a dispersion, in particular a suspension, of a compound having a solubility in water in the range of 0.05 to 10 g / l at 20° C. Alternatively, thickener and wetting agent or dispersant can also be added separately from one another to the aqueous dispersion of a compound having a solubility in water in the range of 0.05 to 10 g / l at 20° C., wherein this variant is less preferred according to the invention.

[0129] Surprisingly, within the scope of the present invention, the above-described aqueous composition comprising at least one thickener and at least one wetting agent or dispersant can be incorporated into a dispersion, in particular a suspension, of a compound having a solubility in water in the range of 0.05 to 10 g / l at 20° C., which is generally highly alkaline, with the introduction of low shear forces. A person skilled in the art would expect that due to the thickener, the viscosity would increase greatly and that a gel could be formed.

[0130] In the context of the present invention, it is advantageously provided that the aqueous dispersion comprises a compound having a solubility in water at 20° C. of less than 5 g / l, in particular less than 4 g / l, preferably less than 3 g / l, more preferably less than 2 g / l, particularly preferably less than 1.5 g / l and even more preferably less than 1 g / l.

[0131] Similarly, it is conceivable that the aqueous dispersion comprises a compound having a solubility in water at 20° C. of greater than 0.1 g / l, in particular greater than 0.2 g / l, preferably greater than 0.3 g / l, more preferably greater than 0.4 g / l.

[0132] In the context of the present invention, it is adequately justified if the aqueous dispersion comprises compounds whose solubility in water at 20° C. is in the range from 0.05 to 5 g / l, in particular from 0.1 to 4 g / l, preferably from 0.2 to 3 g / l, more preferably from 0.2 to 2 g / l, particularly preferably from 0.3 to 1.5 g / l and even more preferably from 0.4 to 1 g / l.

[0133] In the context of the present invention, it is generally also envisaged that the aqueous dispersion comprises the compound having a solubility in water in the range from 0.05 to 10 g / l at 20° C., i.e. having a high residual solubility, in an amount of 40 to 80% by weight, in particular 50 to 75% by weight, preferably 55 to 70% by weight and more preferably 60 to 65% by weight, based on the aqueous dispersion.

[0134] The dispersions according to the invention thus make it possible to obtain compounds having a solubility in water in the range from 0.05 to 10 g / l at 20° C. in very high quantities compared to conventional systems, without changing or degrading the properties of the system into which the dispersions according to the invention are introduced or based on them.

[0135] As mentioned above, within the scope of the present invention, the compound having a solubility in water at 20° C. in the range of 0.05 to 10 g / l is present in the form of particles.

[0136] In the context of the present invention, according to one embodiment, it can be provided that the compound having a solubility in water at 20° C. in the range of 0.05 to 10 g / l has a particle size distribution D10 in the range of 0.05 to 0.5 μm, in particular 0.1 to 0.4 μm, preferably 0.15 to 0.3 μm, more preferably 0.18 to 0.25 μm.

[0137] Similarly, it is envisaged that compounds having a solubility in water at 20° C. in the range of 0.05 to 10 g / l have a particle size distribution D50 in the range of 1.0 to 4 μm, in particular 1.5 to 3.0 μm, preferably 1.8 to 2.7 μm, more preferably 2.0 to 2.5 μm.

[0138] It can also be provided that the compound having a solubility in water at 20° C. in the range of 0.05 to 10 g / l has a particle size distribution D90 in the range of 5.0 to 10 μm, in particular 5.5 to 8.0 μm, preferably 6.0 to 7.5 μm, more preferably 6.5 to 7.0 μm.

[0139] The terms D10, D50 and D90 mean that 10% of all particles, or 50% of all particles or 90% of all particles, respectively, have a smaller particle size.The particle size or particle size distribution can be determined in particular by laser scattering.

[0140] According to this embodiment, it is particularly preferred if the compound having a solubility in water in the range of 0.05 to 10 g / l at 20° C. has a particle size distribution D10 of 0.2 μm, a particle size distribution D50 of 2 to 2.5 μm and a particle size distribution D90 of 6.8 μm. With the above-mentioned particle size distribution, matte pigment pastes and coatings with high opacity can be obtained, in particular using calcium aluminum sulfate (ettringite).

[0141] According to a particularly preferred embodiment of the present invention, the compound having a solubility in water at 20° C. in the range of 0.05 to 10 g / l has a particle size distribution D10 in the range of 0.05 to 0.45 μm, in particular 0.1 to 0.4 μm, preferably 0.15 to 0.3 μm, more preferably 0.18 to 0.25 μm.

[0142] Likewise, according to this embodiment, it can be provided that the compound having a solubility in water at 20° C. in the range of 0.05 to 10 g / l has a particle size distribution D50 in the range of 0.5 to 1.8 μm, in particular 0.6 to 1.5 μm, preferably 0.7 to 1.2 μm, more preferably 0.8 to 1.0 μm.

[0143] Furthermore, according to this embodiment, it can be provided that the compound having a solubility in water at 20° C. in the range of 0.05 to 10 g / l has a particle size distribution D90 in the range of 2.0 to 4 μm, in particular 2.2 to 3.7 μm, preferably 2.5 to 3.5 μm, more preferably 2.8 to 3.2 μm.

[0144] In the context of this preferred embodiment, it is particularly preferred if the compound having a solubility in water in the range of 0.05 to 10 g / l at 20° C. has a particle size distribution D10 of 0.2 μm, a particle size distribution D50 of 0.9 μm and a particle size distribution D90 of 3.0 μm. With these smaller particle sizes and narrower particle size distributions, in particular when using calcium aluminate sulfate, bright color pastes can be produced compared to the above-described embodiments, which can be added to standard pigment pastes in an amount of 15% by weight or more without significantly changing the brightness of the color, the color position or the color intensity. The dispersion according to the invention can also be added to colorants, varnishes and glazes, cosmetic and pharmaceutical compositions, liquid semi-finished products and raw materials for industrial processes, detergents and cleaning agents, impregnation agents and disinfectants, so that long-term stable dispersions can be obtained.

[0145] According to a particular embodiment of the invention, the compound having a solubility in water in the range of 0.05 to 10 g / l at 20° C. has a bimodal particle size distribution. In particular, the compound having a solubility in water in the range of 0.05 to 10 g / l at 20° C. has a bimodal particle size distribution, the particle size and particle size distribution of which are according to the above-mentioned different embodiments. In this way, for example, the color space, color position, color intensity and brightness of the composition (in particular the pigment paste and the resulting coating composition) can be set and determined in a targeted manner.

[0146] Within the scope of the present invention, it is thus possible to stabilize usually highly unstable dispersions of compounds with high residual solubility, in particular semi-finished products, so that they can be stored and further processed without problems. The system according to the invention is particularly suitable for stabilizing calcium aluminate sulfates, in particular ettringite, but the principle can also be applied to any other compounds, in particular inorganic compounds, which have a high residual solubility in aqueous media.

[0147] In the context of the present invention, it is generally envisaged that the aqueous dispersion comprises 0.01 to 5% by weight, in particular 0.05 to 2% by weight, preferably 0.1 to 1% by weight, more preferably 0.1 to 0.5% by weight, of thickener, based on the amount of dispersion.

[0148] Similarly, it can be provided that the dispersion contains at least 0.1% by weight, in particular at least 0.5% by weight, more preferably at least 0.1% by weight, based on the amount of the dispersion, of thickener. Furthermore, it is likewise well established if the dispersion contains at most 5% by weight, in particular at most 2% by weight, preferably at most 1% by weight, more preferably at most 0.5% by weight, based on the amount of the dispersion, of thickener.

[0149] Furthermore, in the context of the present invention it is conceivable that the dispersion comprises at least 0.1% by weight, in particular at least 0.2% by weight, preferably at least 0.3% by weight, more preferably at least 0.5% by weight, based on the amount of the dispersion, of a wetting or dispersant.

[0150] Good results can also be achieved if the dispersion comprises up to 8% by weight, in particular up to 5% by weight, preferably up to 2% by weight, more preferably up to 1% by weight, based on the amount of the dispersion, of wetting or dispersing agent.

[0151] In the context of the present invention, it is also sufficient if the dispersion comprises 0.1 to 8% by weight, in particular 0.2 to 5% by weight, preferably 0.3 to 2% by weight, more preferably 0.5 to 1% by weight, of wetting or dispersing agent, based on the amount of the dispersion.

[0152] In the context of the present invention, it is envisaged that the aqueous dispersion comprises at least 5% by weight, in particular at least 15% by weight, preferably at least 25% by weight, more preferably at least 35% by weight of water, based on the amount of the dispersion.

[0153] Similarly, it can be provided that the aqueous dispersion comprises up to 60% by weight, in particular up to 55% by weight, preferably up to 50% by weight, more preferably up to 45% by weight, of water, based on the amount of the dispersion.

[0154] In the context of the present invention, particularly good results are achieved if the aqueous dispersion comprises 5 to 60% by weight, in particular 15 to 55% by weight, preferably 25 to 50% by weight, more preferably 35 to 45% by weight, of water, based on the amount of the dispersion.

[0155] According to a preferred embodiment, the aqueous dispersion thus comprises

[0156] (i) compounds having a solubility of less than 10 g / l, in particular in an amount of 40 to 80% by weight,

[0157] (ii) at least one thickener, in particular in an amount of 0.1 to 5% by weight

[0158] (iii) at least one wetting agent or dispersant, in particular in an amount of 0.1 to 8% by weight, and

[0159] (iv) Water, in particular in amounts of 5 to 60% by weight, based in each case on the dispersion.

[0160] To this preferred embodiment of the invention, all parameters, features, advantages and characteristics mentioned above in the context of the other embodiments apply.

[0161] In the context of the present invention, it is generally specified that the dispersion contains a pH regulator. In the case of a pH regulator, the pH value is set in particular to a particularly preferred range, both for the stability of the dispersion and to prevent infection by microorganisms.

[0162] The pH adjuster is generally selected from inorganic and organic acids and bases, particularly inorganic and organic bases, preferably inorganic bases.

[0163] If the dispersion contains a pH adjusting agent, it has been found to be sufficient if the pH adjusting agent is selected from the group consisting of hydrochloric acid, sulfuric acid, nitric acid, citric acid, pyridinecarboxylic acid, acetic acid, sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, ammonia, water glass, dimethylglucamine and mixtures thereof. Preferably, the pH adjusting agent is selected from the group consisting of sodium hydroxide, potassium hydroxide, lithium hydroxide, calcium hydroxide, ammonia, water glass, dimethylglucamine and mixtures thereof.

[0164] If the dispersion comprises a pH regulator, the composition generally comprises 0.01 to 10% by weight, in particular 0.1 to 8% by weight, preferably 0.5 to 7% by weight, more preferably 1 to 5% by weight, of pH regulator, based on the amount of the dispersion.

[0165] According to another preferred embodiment, the aqueous dispersion thus comprises

[0166] (i) compounds having a solubility of less than 10 g / l, in particular in an amount of 40 to 80% by weight,

[0167] (ii) at least one thickener, in particular in an amount of 0.1 to 5% by weight

[0168] (iii) at least one wetting agent or dispersant, in particular in an amount of 0.1 to 8% by weight

[0169] (iv) water, in particular in an amount of 5 to 60% by weight

[0170] (iv) at least one pH regulator, in particular in an amount of 0.01 to 10% by weight, based in each case on the dispersion.

[0171] To this preferred embodiment of the invention, all parameters, features, advantages and characteristics mentioned above in the context of the other embodiments apply.

[0172] Advantageously, the dispersion generally comprises at least one additive. Typically, the additive is selected from the group consisting of rheological additives, stabilizers, antifoam components, pH stabilizers, rheology modifiers and mixtures thereof.

[0173] Suitable antifoaming components are usually small amounts of hydrophobic ingredients such as petrolatum (INCI: Petrolatum), castor oil, mineral oil, vegetable oil or silicone compounds known by their INCI names such as bisphenyl hexamethicone, dimethicone, dimethicone silylate, dimethiconol, diphenyl dimethicone, diphenylsiloxyphenyl trimethicone, disiloxane, PEG / PPG-12 / 16 dimethicone, PEG / PPG-12 / 18 dimethicone, PEG / PPG-16 / 8 dimethicone, PEG / PPG-8 / 26 dimethicone, phenethyl disiloxane, phenyl dimethicone. oxane, phenyl trimethicone, polysilicone-1, polysilicone-2, polysilicone-7, polysilicone-8, polysilicone-10, silica dimethicone silylate, silica silylate, simethicone, trimethylsiloxysilicate, trimethylsiloxysilicate / dimethicone crosspolymer, triphenyl trimethicone and trisiloxane, behenyl methacrylate / ethylamine oxide, methacrylate copolymer, C12-14 sec-Pareth-5, hexamidine diisosulfate, hexyldeceth-2, laureth-5 butyl ether, Rhus verniciflua leaf extract, and combinations of hydrophobic components with solids (e.g., silica), such as those from Evonik Industries Alcohols (such as ethanol, isopropanol, hexan-1-ol, propan-2-ol) may also have a defoaming effect, especially when used in large quantities.

[0174] If the dispersion comprises additives, it has proven sufficient if the dispersion comprises 0.01 to 10% by weight, in particular 0.1 to 8% by weight, preferably 0.5 to 6% by weight, more preferably 1 to 5% by weight, of additives, based on the amount of the dispersion.

[0175] According to another preferred embodiment, the aqueous dispersion thus comprises

[0176] (i) compounds having a solubility of less than 10 g / l, in particular in an amount of 40 to 80% by weight,

[0177] (ii) at least one thickener, in particular in an amount of 0.1 to 5% by weight

[0178] (iii) at least one wetting agent or dispersant, in particular in an amount of 0.1 to 8% by weight

[0179] (iv) water, in particular in an amount of 5 to 60% by weight

[0180] (iii) at least one pH adjusting agent, particularly in an amount of 0.01 to 10 wt %, and

[0181] (iv) at least one additive in an amount of 0.01 to 10% by weight, based in each case on the dispersion.

[0182] To this preferred embodiment of the invention, all parameters, features, advantages and characteristics mentioned above in the context of the other embodiments apply.

[0183] Furthermore, all embodiments of the aqueous dispersion preferably comprise an alkaline pH value. In this context, it has been particularly well established if the pH value of the dispersion is 9.5 or higher. Particularly good results are obtained if the pH value of the dispersion is in the range of 9.5 to 14, preferably 9.5 to 13, preferably 9.5 to 12, particularly preferably 9.5 to 11.5, even more preferably 10.2 to 11.4.

[0184] In the context of the present invention, it is generally envisaged that the dispersion is at least substantially free of preservatives, in particular free of preservatives.

[0185] Likewise, in the context of the present invention, it is preferably provided that the dispersion is at least substantially free of biocides, in particular free of biocides.

[0186] The dispersions according to the invention are preferably preservative-free, biocide-free and volatile organic compound-free, i.e. VOC-free, so that they generally do not contain any substances requiring declaration and can be used in a variety of ways without any problems arising with regard to environmental protection, health protection and occupational safety.

[0187] Furthermore, the dispersion according to the invention is storage-stable, in particular for a period of at least 2 months, in particular for at least 4 months, in particular for at least 6 months, preferably for at least 12 months. Likewise, it is conceivable that the dispersion according to the invention is storage-stable for a period of 2 to 36 months, in particular for 4 to 20 months, in particular for 6 to 18 months, preferably for 12 to 15 months.

[0188] The term "storage-stable" means that the physical and chemical properties of the composition do not change during storage, or change only to such an extent that the application properties of the composition are not impaired.

[0189] Furthermore, it has proven sufficient if the dispersion has a dynamic viscosity according to Brookfield at 25° C. in the range from 50 to 500 mPas, in particular from 60 to 300 mPas, preferably from 100 to 200 mPas.

[0190] For further details on this aspect of the invention, reference may be made to the above-mentioned configurations of the other aspects of the invention, which configurations apply correspondingly to the aqueous dispersion according to the invention.

[0191] Furthermore, according to a fourth aspect of the invention, a further subject of the invention is a process for producing the above-mentioned aqueous dispersion, wherein a dispersion comprising at least one compound having a solubility in water in the range of 0.05 to 10 g / l at 20° C. is provided and the above-mentioned aqueous composition is added.

[0192] Particularly good results are obtained in the context of the present invention if the aqueous composition is added with the introduction of shear forces. The introduction of shear forces can be carried out by means of conventional mixing apparatuses, in particular dissolvers.

[0193] For more details about the method according to the present invention, reference may be made to the above-mentioned configurations related to other aspects of the present invention, which configurations are also applicable to the method of the present invention where appropriate.

[0194] The subject matter of the invention will be illustrated below in a non-limiting manner with reference to the following examples.

[0195] Example

[0196] 1. Calcium Aluminate Sulfate

[0197] The calcium aluminate sulfate suspension forms an insoluble precipitate after a short time, which cannot be dispersed again. This precipitate is initially formed by precipitation of the calcium aluminate sulfate component and then hardens as part of the Ostwald ripening process.

[0198] This sedimentation behavior can be characterized by LUMiSizer measurements. The LumiSizer is an analytical centrifuge from the manufacturer LUM with integrated optical sensors for analyzing and characterizing particle and droplet velocities for emulsification and sedimentation phenomena. Micro cuvettes are used for low-viscosity samples. For the evaluation, the cuvette position in the LumiSizer is plotted against the measured light transmittance. To determine the sedimentation behavior, the sample is subjected to accelerated sedimentation and irradiated at fixed time intervals using an 865 nm laser. The transmittance provides information about the sedimentation behavior of the sample. The faster the sample settles within the defined time interval, the more unstable it is. This results in a high value for the instability index.

[0199] Figure 1The sedimentation curve of a commercially available calcium aluminate sulfate suspension in the LUMiSizer is shown. The specific gravity of the calcium aluminate sulfate suspension is 1.40 g / cm 3 , a solids content of 60 to 64% by weight, a particle size distribution of d10 = about 0.2 μm, d50 = about 0.9 μm and d90 = about 3.0 μm.

[0200] According to the increase in surface transmittance, opaque components are deposited at the bottom of the cuvette - a sediment is formed. The light grey to dark grey gradient forms the third dimension as a time axis. Light grey measured values ​​occur earlier in time, while dark grey values ​​are recorded at the end of the measurement. The representation of the evaluation can be customized. The dispersion stability is usually indicated by an instability index. The instability index is calculated by the device software as a dimensionless value using the sedimentation velocity of the dispersed particles and is always related to the time t. The time t = 500 seconds is usually selected to represent the instability index.

[0201] like Figure 2 As shown, the stability index of the commercially available calcium aluminate sulfate suspension used at time t=500 seconds was 0.387.

[0202] Stabilization of calcium aluminate sulfate suspension

[0203] Preparation of premix (composition of the present invention)

[0204] In order to stabilize the stability of the calcium aluminate sulfate suspension, an aqueous composition according to the invention comprising a wetting agent or dispersant and a thickener is prepared.

[0205] Preparation of the composition according to the invention The premixes given in Table 1 for preparing the dispersion E1 according to the invention are used as examples:

[0206] An aqueous dispersion (solid content 40 wt%) of 90 wt% of a wetting agent or dispersant (maleic acid styrene copolymer with pigment-affinity groups) was introduced and 10 wt% of a thickener (water-soluble nonionic hydroxyethyl cellulose) was added under stirring. The thickener was uniformly dispersed and no gelling or thickening of the dispersion was observed.

[0207] Preparation of the dispersion according to the invention

[0208] Preparation of the Dispersion According to the Invention The preparation of the dispersion E1 according to the invention is exemplified.

[0209] To prepare the dispersion E1 according to the invention, 98% by weight of a commercial calcium aluminate sulfate suspension (solids content 62% by weight) was introduced and slowly mixed with 2% by weight of the premix (composition according to the invention) under stirring. The mixture was then stirred in a dissolver for 30 minutes. A low-viscosity dispersion was obtained which could be stored for several months with virtually no precipitation.

[0210] Further embodiments E2 to E6 according to the invention are obtained accordingly from premixes, ie aqueous dispersions of wetting agents or dispersants and thickeners. The exact composition of the dispersions E1 to E6 according to the invention is given in Table 1.

[0211] from Figure 3 and 4 As can be seen, the calcium aluminate sulfate suspension can be stabilized in the form of dispersion E1:

[0212] The measurement was carried out four times and a commercial calcium aluminate sulfate suspension was used as a standard. The standard calcium aluminate sulfate suspension had completely settled at time t=500 s (stability index 0.358), while the settling time of the stable dispersion was greatly delayed.

[0213] The stability index of the dispersions according to the invention at a time t=500 seconds is in the range from 0.037 to 0.064 (see Figure 3 ), the stability index is increased by 15 times compared with the commercially available calcium aluminate sulfate suspension.

[0214] In stark contrast to unstabilized commercial calcium aluminate sulfate suspensions, no non-redispersible precipitates are formed in the calcium aluminate sulfate suspensions stabilized according to the invention. If precipitates are formed, they can be redispersed without any problems, since Ostwald ripening is suppressed in the suspensions stabilized according to the invention.

[0215] Table 1: Composition (expressed in weight percent) of the calcium aluminate sulphate suspensions used and of the dispersions E1 to E6 according to the invention; when aqueous dispersions were used as starting materials, the solids content (expressed in weight percent) is given in each case in brackets

[0216]

[0217] Comparative Example

[0218] In order to illustrate the performance of the system according to the invention, comparative tests V1 to V6 were carried out, in each of which 99% by weight of a commercial calcium aluminate sulfate suspension was mixed with 1 part by weight of thickener. The exact composition can be found in Table 2.

[0219] The stability index of the dispersion was then determined at time t = 500 seconds. The results are shown in Figure 5 It can be seen that only the dispersion E1 according to the invention achieves a significant stability. In some cases, the stability of dispersions V1 to V6 increases slightly, but the viscosity of all dispersions V1 to V6 increases significantly.

[0220] Table 2: Compositions given in weight percent of the calcium aluminate sulphate suspensions used, dispersion E1 according to the invention and comparative dispersions V1 to V6; when aqueous dispersions were used as starting materials, the solids content is given in each case in brackets in weight percent

[0221]

[0222] 2. Calcium silicate hydrate

[0223] For the following tests, a commercially available aqueous calcium silicate hydrate suspension was used, which had a calcium silicate hydrate content of 50% by weight. The suspension exhibited rapid sedimentation, during which an insoluble, non-redispersible sediment was formed.

[0224] A sample of this suspension (Sample V) was examined using a LUMiSizer. Figure 6 As shown, and the stability index after 500 seconds is 0.156.

[0225] Another sample of the calcium silicate hydrate suspension (Sample E) was mixed with the premix of wetting agent or dispersant and thickener used to produce the calcium aluminate sulfate Sample El.

[0226] To produce the premix, 90% by weight of an aqueous dispersion (solids content 40% by weight) of a wetting or dispersant (maleic acid styrene copolymer with pigment-affinity groups) was introduced and 10% by weight of a thickener (water-soluble nonionic hydroxyethylcellulose) was added with stirring.

[0227] Then 2 wt% of this premix was mixed with 98 wt% of calcium silicate hydrate suspension and the mixture was analyzed using LUMiSizer (Sample E). Figure 6 As shown, the stability index after 500 seconds is 0.037. The settling behavior is again significantly improved, in particular the formation of sediments that cannot be redispersed is effectively prevented; if sediments are formed, they can be easily redispersed.

[0228] Figure 7 A comparison of the development of the stability index of a commercial calcium silicate hydrate suspension (sample V) and a calcium silicate hydrate suspension stabilized according to the invention (sample E) is shown. Here, too, the significantly lower and time-delayed sedimentation of the sample according to the invention is impressively demonstrated.

Claims

1. Aqueous compositions, in particular solutions or dispersions, for stabilizing dispersions comprising compounds having a solubility in water at 20° C. in the range from 0.05 to 10 g / l, Features The composition comprises (a) at least one thickener and (b) at least one wetting agent or dispersant.

2. The aqueous composition according to claim 1, characterized in that The dispersion to be stabilized comprises a compound having a solubility in water at 20° C. in the range from 0.05 to 5 g / l, in particular from 0.1 to 4 g / l, preferably from 0.2 to 3 g / l, more preferably from 0.2 to 2 g / l, particularly preferably from 0.3 to 1.5 g / l, even more preferably from 0.4 to 1 g / l.

3. The aqueous composition according to any one of the preceding claims, characterized in that The thickener is selected from the group consisting of polysaccharides, proteins, polyvinyl alcohol, silicic acids, silicates and mixtures thereof.

4. The aqueous composition according to any one of the preceding claims, characterized in that The thickener is selected from the group consisting of xanthan gum, beta-glucan, thiolated polysaccharides, proteoglycans, gum arabic, gum karaya, gum tragacanth, locust bean gum, guar gum, quince gum, pectin, agar, carrageenan, alginates, starch, starch derivatives, cellulose, cellulose derivatives, in particular cellulose ethers, silicic acids, bentonites, layered silicates, polyvinyl alcohol, gelatin, casein and mixtures thereof.

5. The aqueous composition according to claim 4, characterized in that The thickener is selected from xanthan gum, β-glucan, thiolated polysaccharide, proteoglycan, cellulose ether, silicic acid, bentonite, layered silicate, polyvinyl alcohol, gelatin, casein and mixtures thereof.

6. The aqueous composition according to claim 4 or 5, characterized in that The thickener is a cellulose ether.

7. The aqueous composition according to any one of the preceding claims, characterized in that The wetting agent or dispersant is selected from the group consisting of polymers having pigment-affinity groups, silicone-modified polymers, block copolymers, graft copolymers, surfactants, modified natural oils, and mixtures thereof.

8. The aqueous composition according to any one of the preceding claims, characterized in that The wetting or dispersing agent is selected from the group consisting of polycarboxylates, in particular salts of polyacrylic acids, polyphosphates, in particular linear polyphosphates and / or cyclic metaphosphates, polyether phosphates, polycarboxylic acid polymers, acrylic block copolymers, polyurethanes, ethoxylated fatty alcohols, nonionic saturated long-chain alcohols, fatty alcohol sulfates, alkyl phosphonates, silicone ethers, in particular methoxypolyethoxypropyl trisiloxanes, alkyl glycol ethoxylates, surfactants, gemini surfactants, bola surfactants, fluorosurfactants, modified natural oils and mixtures thereof.

9. The aqueous composition according to claim 8, characterized in that The wetting agent or dispersant is selected from the following group: salts of polyacrylic acids, polyphosphates, in particular linear polyphosphates and / or cyclic metaphosphates, polyether phosphates, polycarboxylic acid polymers, acrylic block copolymers, polyurethanes, ethoxylated fatty alcohols, nonionic saturated long-chain alcohols, fatty alcohol sulfates / salts, alkyl phosphonates / salts, polysiloxane ethers, in particular methoxypolyethoxypropyl trisiloxanes, alkyl glycol ethoxylates, gemini surfactants, bola surfactants, modified natural oils and mixtures thereof.

10. The aqueous composition according to claim 9, characterized in that The wetting agent or dispersant is selected from the following group: sodium salts of polyacrylic acids, ammonium salts of polyacrylic acids, polyether phosphates, polycarboxylic acid polymers, modified styrene-maleic acid copolymers, polysiloxane ethers, especially methoxypolyethoxypropyl trisiloxanes, gemini surfactants, bola surfactants, modified natural oils and mixtures thereof.

11. The aqueous composition according to any one of the preceding claims, characterized in that The composition has a weight ratio of thickener to wetting agent or dispersant (thickener:wetting agent or dispersant) in the range of 2:1 to 1:20, in particular 1:1 to 1:15, preferably 1:1 to 1:10, more preferably 1:2 to 1:8, particularly preferably 1:3 to 1:

5.

12. The aqueous composition according to any one of the preceding claims, characterized in that The composition comprises 1 to 20% by weight, in particular 2 to 18% by weight, preferably 5 to 15% by weight, more preferably 8 to 12% by weight of the thickener, based on the amount of the composition.

13. The aqueous composition according to any one of the preceding claims, characterized in that The composition comprises 20 to 65% by weight, in particular 25 to 60% by weight, preferably 30 to 55% by weight, more preferably 35 to 50% by weight, of the wetting agent or dispersant, based on the amount of the composition.

14. The aqueous composition according to any one of the preceding claims, characterized in that The composition comprises 15 to 79% by weight, in particular 30 to 78% by weight, preferably 30 to 63% by weight, more preferably 38 to 57% by weight, of water, based on the amount of the composition.

15. Use of an aqueous composition according to any one of claims 1 to 14 for stabilizing an aqueous dispersion comprising at least one compound having a solubility in water at 20° C. in the range from 0.05 to 10 g / l, in particular from 0.05 to 5 g / l, preferably from 0.1 to 4 g / l, more preferably from 0.2 to 3 g / l, particularly preferably from 0.2 to 2 g / l, even more preferably from 0.3 to 1.5 g / l, particularly preferably from 0.4 to 1 g / l.

16. An aqueous dispersion, especially a semi-finished product, comprising (i) at least one compound having a solubility in water at 20° C. in the range of 0.05 to 5 g / l, (ii) at least one thickener and (iii) at least one wetting agent or dispersant.

17. Process for producing an aqueous dispersion according to claim 16, characterized in that A dispersion comprising at least one compound having a solubility in water in the range of 0.05 to 10 g / l at 20° C. is provided and an aqueous composition according to one of claims 1 to 13 is added.

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