Plaster system for direct application onto old wall or floor coverings in damp rooms

Abstract

Plaster primer composition comprehensive - at least 50% by weight of a calcium carbonate filler; - 8 to 25 wt% of an acrylate binder containing carboxyl groups and silane groups; - a transition metal salt with at least divalent cations and - 10 to 25% by weight water.

Description

[0001] The present invention relates to a plaster system consisting of a plaster primer composition and a brushable surface plaster composition, which can be applied directly to a tiled surface without the need to remove the tiles beforehand. The present invention further relates to the plaster primer composition and the brushable surface plaster composition as components of the plaster system, and to surfaces onto which such a plaster system has been applied. State of the art

[0002] Older buildings often feature tiled walls and floors. To minimize the workload of removing old tiles and disposing of the waste material during renovations, these old tiles are usually not removed but simply covered with new ones to create the renovated surfaces. However, when redesigning a room layout, it may be necessary to replace a tiled surface with plaster instead of retiling it. For such applications, a plaster system is needed that can be applied directly and with good adhesion to these tiled surfaces, effectively covering and smoothing the grout lines so that they are no longer visible in the finished surface.Ideally, such a system should be as simple as possible to process, requiring only a few steps, and should convey a visually mineral surface impression after installation.

[0003] Mineral plaster systems for application to wall and floor surfaces are known in themselves. For example, EP 2 059 571 B1 describes a formulation for plasters and paints that can be used indoors and outdoors, comprising a mineral filler, a pigment, colloidal silicon dioxide, and an aqueous polymer dispersion containing a copolymer produced by emulsion polymerization. The examples in the document describe copolymer emulsions of methacrylic acid, methyl methacrylate, butyl acrylate, and vinyl triethoxysilane, in which methyl methacrylate and butyl acrylate are the main monomers of the copolymer.

[0004] EP 2 998 367 A1 describes silicate plaster coating compounds containing at least one silicate and / or calcitic filler, at least one lightweight filler, silica sol, at least one water glass, aggregate material, at least one organic binder, additives, and water. The specified plaster coating compounds are intended to be easier to work with than conventional plasters and to produce plasters with very good color stability.

[0005] EP 4 389 719 A1 describes pasty plasters and methods for processing such plasters, which are formed from a polymer binder, a granular and / or sandy filler coated with at least one color pigment and at least one binder, a water-repellent agent, at least one uncoated granular and / or sandy filler, further additives, and water. The coated granular and / or sandy filler is to be produced by coating the uncoated filler with a mixture of color pigment and binder and subsequent drying.

[0006] WO 2005 / 100279 A1 describes a coating material for drywall partitions, consisting of water, a binder, a filler containing at least 60% by weight of CaCO3, and a non-cellulosic thickener. In the examples in this document, an acrylate resin in the form of AC-630 resin is used as the binder, a sodium polyacrylate dispersant, and an acrylate-methacyric acid copolymer as the thickener.

[0007] The aforementioned state-of-the-art documents do not describe any plaster compositions and systems specifically formulated for application on tile substrates. Therefore, there is a need for a plaster system that can be easily applied to such substrates and provides durable adhesion to ceramic surfaces.

[0008] Ideally, such a system should be applied by roller (instead of troweling) to simplify the application process and, after hardening, should provide a homogeneous, mineral-like surface appearance. Especially in the area directly facing the surface, the plaster should contain only low levels of flammable / organic polymeric components to meet increased fire protection requirements. Furthermore, there is a need for a suitable plaster system that offers microbial resistance without requiring the inclusion of conventional organic-chemical biocides in its composition.

[0009] The present invention addresses this need. Detailed description of the invention

[0010] The investigations underlying this invention found that a plaster primer composition containing 8 to 25 wt% acrylate binder with carboxyl and silane groups, in combination with a transition metal salt with at least divalent cations used as a crosslinking agent, and calcium carbonate as the bulk filler, provides excellent adhesion to tiles and other ceramic surfaces. A plaster composition, also essentially composed of calcium carbonate filler, can then be applied to this primer to create a mineral surface appearance.The plaster composition also contains only a minimal amount of added organic binder to provide high fire protection properties, as well as platelet-shaped talc to give the plaster composition a consistency suitable for application by rollers.

[0011] Accordingly, the present invention relates in a first aspect to a plaster primer composition comprising at least the following components: - at least 50% by weight of a calcium carbonate filler; - 8 to 25 wt% of an acrylate binder containing carboxyl groups and silane groups; - a transition metal salt with at least divalent cations; and - 10 to 25% by weight water.

[0012] The calcium carbonate filler is generally a particulate material such as ground limestone, limestone sand, or limestone flour. Preferably, the calcium carbonate filler has a mean particle size of no more than 1 mm, and typically in the range of 1 to 200 µm, whereby the mean particle size is to be determined by a suitable sieving method (e.g., according to DIN 66165) and is based on the weight fraction of the calcium carbonate filler.

[0013] Preferably, the proportion of calcium carbonate filler in the plaster primer composition is at least 55 wt.%, more preferably at least 60 wt.%, and even more preferably at least 65 wt.%. The upper limit of the amount of calcium carbonate filler is determined by the sum of the other components of the plaster primer composition, which, together with the proportion of calcium carbonate filler, equals 100 wt.%. In addition to calcium carbonate, the calcium carbonate filler may contain proportions of minerals other than calcium carbonate, such as up to 10 wt.% calcium / magnesium carbonate (dolomite), up to 10 wt.% quartz, up to 5 wt.% feldspar, and / or up to 5 wt.% mica and / or potassium aluminum silicate (muscovite). In this case, these minerals are to be included in the calcium carbonate filler. However, it is preferred that the calcium carbonate filler contains at least 85 wt.% calcium carbonate.-% and preferably at least 90 wt.%.

[0014] The acrylate binder containing carboxyl and silane groups is preferably an acrylate binder in which the binder is first produced from the relevant monomers, and subsequently pre-hydrolyzed silane is added. The acrylate binder is furthermore a copolymeric binder composed of at least 40 wt.%, based on the total amount of monomers, of vinyl esters of acrylic and / or methacrylic acids and optionally a vinylaromatic monomer. Preferably, the acrylate binder is a styrene acrylate binder in which 40 wt.%, based on the total amount of monomers, is composed of vinyl esters of acrylic and / or methacrylic acids and styrene as the vinylaromatic monomer. More preferably, the proportion of these comonomers is at least 50 wt.%, even more preferably at least 60 wt.%, and even more preferably at least 70 wt.%.

[0015] The acrylate binder also contains o,β-ethylene-unsaturated mono- and / or dicarboxylic acids as monomers, preferably in a proportion of 0.1 to 10 wt.% based on the total amount of monomers. These monomers provide the carboxyl groups in the binder.

[0016] As mentioned above, pre-hydrolyzed silane can be added to the acrylate binder to produce an acrylate binder containing carboxyl and silane groups. Alternatively, unsaturated monomers having at least one alkoxysilyl group can also be incorporated into the acrylate binder, preferably in an amount of 0.5 to 15 wt.% based on the total amount of monomer.

[0017] Preferred monomers in the form of vinyl esters of acrylic and / or methacrylic acids are methyl acrylate, ethyl acrylate, propyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, methyl methacrylate, ethyl methacrylate, propyl methacrylate, n-butyl methacrylate, t-butyl methacrylate, isobutyl methacrylate, 2-ethylhexyl methacrylate, cyclohexyl methacrylate, and cyclohexyl acrylate. These alkyl esters can be used alone or in combination with other esters.

[0018] The vinylaromatic monomer is preferably styrene.

[0019] Examples of o,β-ethylene-unsaturated mono- and / or dicarboxylic acids that can be used to prepare the acrylate binder are ethylene-unsaturated C3-C8 monocarboxylic acids and ethylene-unsaturated C4-C8 dicarboxylic acids, as well as half-esters of ethylene-unsaturated C4-C8 dicarboxylic acids. These monomers typically have up to eight carbon atoms, particularly three to eight. Preferred α,β-ethylene-unsaturated mono- and / or dicarboxylic acids are, in particular, ethylene-unsaturated C3-C8 monocarboxylic acids, such as acrylic acid, methacrylic acid, and crotonic acid. Ethylenically unsaturated C4-C8 dicarboxylic acids, such as maleic acid, fumaric acid, itaconic acid and citraconic acid, as well as their monoamides or semi-esters with C1-C12 alkanols, preferably C1-C4 alkanols, such as monomethyl maleate and mono-n-butyl maleate.Furthermore, in addition to or instead of the aforementioned acids, their salts can also be used, preferably their alkali metal or ammonium salts and particularly preferably their sodium salts, such as the sodium salts.

[0020] Examples of ethylene-unsaturated monomers that possess at least one alkoxysilyl group are silanes of the formulas CH2=CR 1 -(CH2) 0-1 Si(CH3) 0-1 (OR 2 ) 3-2 and CH2=CR 3 CO2-(CH2)3Si (CH3) 0-1 (OR 4 ) 3-2 , where R 1 R stands for hydrogen or methyl 2 an unbranched or branched, optionally substituted alkyl group with 1 to 12 carbon atoms and R 3 and R 4Each is independently either hydrogen or C1-C6 alkyl. Particularly preferred silanes are vinylmethyldimethoxysilane, vinylmethyldiethoxysilane, vinylmethyldi-n-propoxysilane, vinylmethyldi-iso-propoxysilane, vinylmethyldi-n-butoxysilane, vinylmethyldi-sec-butoxysilane, vinylmethyldi-tert-butoxysilane, vinylmethyldi-(2-methoxyisopropyloxy)-silane, and vinylmethyldioctyloxysilane.

[0021] Other suitable examples of ethylene-unsaturated monomers with at least one alkoxysilyl group are γ-(Meth)acryloxypropyl-tris-(2-methoxyethoxy)silane, γ-(Meth)acryloxypropyl-tris-methoxysilane, γ-(Meth)acryloxypropyl-tris-ethoxysilane, γ-(Meth)acryloxypropyl-tris-n-propoxysilane, γ-(Meth)acryloxypropyl-tris-iso-propoxysilane, γ-(Meth)acryloxypropyl-tris-butoxysilane, γ-Acryloxypropyl-tris-(2-methoxyethoxy)silane, γ-Acryloxypropyl-tris-methoxysilane, γ-Acryloxypropyl-tris-ethoxysilane, γ-Acryloxypropyl-tris-n-propoxysilane. γ-acryloxypropyl-tris-iso-propoxysilane, γ-acryloxypropyl-tris-butoxysilane, as well as vinyl-tris-(2-methoxyethoxy)-silane, vinyl-tris-methoxysilane, vinyl-tris-ethoxysilane, vinyl-tris-n-propoxysilane, vinyl-trisiso-propoxysilane and vinyl-tris-butoxysilane.

[0022] During the processing and application of the plaster primer composition to a ceramic surface, alkoxysilyl groups initially react with water to form SiOH groups. These then react with silicates or SiO compounds present on the ceramic surface, forming Si-O-Si bonds that firmly anchor the binder to the ceramic surface. The acid groups, through the addition of transition metal salts with at least divalent cations (M), enable further action. 2+ ) the formation of networks via the formation of (C=O)OMO(C=O) bridges, which gives the composition improved hardness and sufficient water resistance.

[0023] The quantity of acrylate or styrene acrylate binder refers to the solid content of the binder contained in an added solution or dispersion of the binder, wherein the solution or dispersion typically contains water as an additional solvent. The solid content of this dispersion is preferably in the range of 30 to 70 wt.% and particularly 40 to 60 wt.%, with the remaining 100% being the solvent, and in particular water.

[0024] The water contained in the plaster primer serves to give it a pasty consistency suitable for application and processing, allowing it to be applied to a substrate, for example, with a roller. During application, most of the water evaporates, so that only traces of the original amount of water contained in the plaster primer remain in the finished surface.

[0025] In a preferred embodiment, a zinc salt, particularly in the form of zinc chloride, zinc hydroxide, zinc oxide, or zinc acetate, is used as the transition metal salt in the plaster primer composition according to the invention. When zinc hydroxide, zinc oxide, or zinc acetate is used, the hydroxy, oxy, or acetate groups of the zinc salt can react with carboxyl groups of the binder, forming water or acetic acid. This can subsequently escape from the mixture, while the zinc ions remain in the mixture, forming a cross-link.

[0026] In a further preferred embodiment, the plaster primer composition according to the invention additionally contains silicone (in anhydrous form), preferably in an amount in the range of 0.1 to 2.5 wt.%, and more preferably 0.2 to 1.5 wt.%. In this way, the water resistance of the plaster primer composition is adjusted or achieved to a desired level.

[0027] In a further preferred embodiment, the plaster primer composition according to the invention further comprises a white pigment, preferably in the form of titanium dioxide, and more preferably in an amount in the range of 2.5 to 5 wt.%. The added white pigment allows the desired opacity of the plaster primer composition to be achieved.

[0028] In a further preferred embodiment, the plaster primer composition according to the invention further comprises platelet-shaped talc or platelet-shaped kaolin, in particular platelet-shaped talc, which may expediently be included in the composition in an amount of up to 5% by weight, based on the calcium carbonate filler. Additionally or alternatively, it is preferred if the calcium carbonate filler in the plaster primer composition according to the invention consists of portions with different fineness of milling (i.e., finer and coarser portions). Such a composition can generally be identified by the particle size distribution by means of several maxima. The addition of platelet-shaped talc and / or the inclusion of calcium carbonate filler portions with different fineness of milling can improve the rollability during processing or application of the plaster primer composition.

[0029] In a further preferred embodiment, the plaster primer composition according to the invention contains at least one organic or inorganic thickener, preferably in an amount in the range of 0.01 to 1.0 wt.% based on the total plaster primer composition. The addition of a thickener improves the settling behavior of larger quantities of plaster primer composition, which can occur, for example, in the joints of a tiled substrate, in order to produce the smoothest possible surface after application of the plaster primer composition.

[0030] Further additives that can be used in the plaster primer composition according to the invention are coalescing agents, stabilizers, emulsifiers, dispersing agents, preservatives, fibers, microsilicates, or kaolin. Such further additives (including the amount of any thickener optionally included) are preferably present in the plaster primer composition in an amount in the range of 8 wt.% or less and preferably up to 5 wt.% or less. For the individual components coalescing agents, stabilizers, emulsifiers, and dispersion aids, a proportion of 0.01 to 1.0 wt.% based on the total weight of the plaster primer composition can be specified as a suitable proportion.

[0031] Suitable wetting and dispersing agents include polyacrylates or salts of polyacrylic acid, phosphate esters, and tetraalkylammonium phosphate, or mixtures thereof. Furthermore, suitable wetting and dispersing agents can also be amine compounds such as butylamine, dibutylamine, triethylamine, N-oleyl-1,3-propanediamine, dimethylaminoethanol, diethylaminoethanol, aminomethylpropanol, 2-dibutylaminoethanol, or any mixtures thereof. Quaternary ammonium compounds (QACs), e.g., in aqueous solutions, can be used as stabilizers. Organosilicones, e.g., potassium and / or sodium methyl siliconate, and / or tetraalkylalkylenediamine can also be used.

[0032] Particularly suitable preservatives for use in the plaster primer composition according to the invention are 1,2-benzisothiazol-3(2H)-one and / or 2-methyl-2H-isothiazol-3-one, wherein it is preferred if the total amount of these preservatives does not exceed 0.05 wt.% and in particular 0.03 wt.%.

[0033] In another aspect, the present invention relates to a brushable surface plaster composition comprising the following components: - at least 50% by weight of a calcium carbonate filler; - 1.5% by weight or less of organic binder; - 2.5 to 6 wt% talc; and - Contains 10 to 30% water by weight.

[0034] The term "brushable" in connection with the surface plaster composition indicates that the composition has a consistency suitable for application by brushing or rolling (similar to applying paint with a roller) and can be processed with appropriate application materials. When applying the plaster in this way, layer thicknesses of 1.0 to 4.0 mm are typically applied to the surface to be treated in each application.

[0035] In the specified brushable surface plaster composition, the quantity given for the organic binder refers to the dry quantity of the binder, which is usually used as a solution or dispersion for the formulation of the composition.

[0036] With regard to the calcium carbonate filler, reference can be made to the above information in connection with the plaster primer composition according to the invention for preferred embodiments and quantity specifications.

[0037] In the brushable surface plaster composition, the proportion of organic binder is limited to 1.5% by weight, based on the total mass of the composition, in order to provide a high level of fire protection. Additionally, the low binder content, which is usually a polymer material, reduces static charge buildup in the plaster surface.

[0038] The talc contained in the surface plaster composition (as a plate-shaped filler) reduces the internal friction of the composition and thus improves the rollability of the composition.

[0039] In a preferred embodiment, the binder in the brushable surface plaster composition is a mixture of vinyl acetate-ethylene copolymer and alkyd resin binder. An alkyd resin is a resin obtained by the condensation of polyhydric alcohols and polyprotic acids, which chemically represents a polyester. A polyhydric alcohol frequently used in alkyd resins is, for example, glycerol, while phthalic acid is predominantly used as the polyprotic acid. Alcohol groups present in the resin that are not bound in esters can be in free form or esterified, e.g., with fatty acids such as linoleic acid.

[0040] In the surface plaster composition according to the invention, an air-drying alkyd resin is preferably used, which polymerizes under the influence of oxygen via double bonds of unsaturated fatty acid residues contained in the resin.

[0041] The vinyl acetate-ethylene copolymer and alkyd resin binders are preferably used in a ratio of 3:1 to 1:3 and more preferably in a ratio of 1:2 to 1:1 in the surface plaster composition. Such a mixture ensures good adhesion of the surface plaster composition to a primer composition (or a layer of the surface plaster composition applied in a previous step), good water resistance, and a mineral surface appearance.

[0042] In a further preferred embodiment, the brushable surface plaster composition additionally contains a polyurethane thickener. Such a thickener provides a surface plaster composition with improved application properties via roller application.

[0043] In addition to the polyurethane thickener, it can be advantageous to include one or more other types of thickeners in the surface plaster composition. Suitable thickeners include, for example, polysaccharides, preferably in the form of cellulose ethers, acrylate thickeners, natural or synthetic inorganic thickeners, in particular hectorites, bentonites and / or smectites, modified starch, xanthan gum, guar gum, or any mixtures thereof. Preferably, these additional thickeners are selected from the group comprising hydroxyethylcellulose, xanthan gum, hectorite, and acrylate thickeners. The addition of such thickeners, in combination with the polyurethane thickener, achieves optimized rollability and stability, ensuring good coverage of underlying tile joints while preventing the substrate from showing through, even at application rates greater than 1 mm.

[0044] The total amount of thickeners contained in the brushable surface plaster composition is preferably 1% by weight or less, based on the total weight of the surface plaster composition.

[0045] In a further preferred embodiment, the brushable surface plaster composition also contains zinc oxide, preferably in an amount in the range of 0.25 to 1.0 wt.%, and / or CaOAl₂O₃CaSO₄ × n H₂O (stabilized solution of ettringite) as a white pigment, preferably in an amount in the range of 1 to 5 wt.% in the brushable surface plaster composition. The inclusion of zinc oxide or white pigments imparts antifungal properties that inhibit the growth of fungi on the plaster surface.

[0046] The inclusion of the aforementioned white pigments generally achieves a sufficient antifungal effect, so that the addition of further biocides, such as CIT (chloromethylisothiazolinone), can be omitted. In a preferred embodiment, the brushable surface plaster composition according to the invention therefore contains no additional biocides besides the aforementioned white pigments and can be described as biocide-free according to the criteria of VDL 011 and / or the Blue Angel ecolabel.

[0047] In a further preferred embodiment, the brushable surface plaster composition additionally contains up to 1 wt.% of hydrophobic microhollow spheres and / or up to 0.5 wt.% fibers, particularly in the form of organic fibers. Examples of organic fibers include, in particular, polyolefin fibers such as polypropylene fibers, polyamide fibers, carbon fibers, cellulose fibers and / or acrylic fibers, with cellulose fibers being especially preferred.

[0048] The inclusion of hydrophobic microspheres makes the surface plaster composition lighter and more elastic, with the reduced weight of the composition thus relieving stress on the substrate through lower shear and tensile forces. The addition of cellulose fibers acts similarly to micro-reinforcement, absorbing stresses that arise during drying. The incorporated fibers distribute moisture and stresses more homogeneously, resulting in a more even drying of the surface. Overall, the incorporated fibers provide improved mechanical stability through increased tensile and flexural strength.

[0049] In a further preferred embodiment, the surface plaster composition according to the invention also contains pigments, in particular in the form of titanium dioxide as a white pigment, preferably in an amount in the range of 5.0 to 10.0 wt.%, and more preferably 5.5 to 8.0 wt.%. The desired opacity can be achieved in the surface plaster composition by adding titanium dioxide.

[0050] Additionally, the surface plaster composition may also contain up to 4 wt. aluminum calcium oxide sulfate (Al2Ca6O6(SO4)3).

[0051] In a further preferred embodiment, the brushable surface plaster composition additionally contains at least one further additive, which is selected in particular from the group consisting of surface additives, microsilicates, stabilizers, setting regulators, wetting and dispersing agents, film formers, and defoamers. Such additional additives, when included in the surface plaster composition according to the invention, are preferably present in a total amount of 5% by weight or less, and in particular 3% by weight or less. A reasonable upper limit for the individual additives can be specified as an amount of 1% by weight.

[0052] Regarding substances specifically suitable as stabilizers or wetting and dispersing agents, reference can be made to the above information in connection with the plaster primer composition. For example, mineral oils, siloxanes, and / or silica can be used as defoamers. Suitable film-forming agents are known to those skilled in the art.

[0053] In a particularly preferred embodiment, the plaster primer composition according to the invention is formed from the following components: Table 1 Limestone sands 50 to remaining quantity* Water 10 to 25% by weight Styrene acrylate binder 8 to 25 wt.% Pigments (especially TiO2) 2.5 to 5.0 wt.% Metal salt crosslinker 0.1 to 1.0 wt.% Coalescent agent 0.01 to 1.0 wt.% Stabilizers 0.01 to 1.0 wt.% Thickener 0.01 to 1.0 wt.% Emulsifiers and dispersants 0.01 to 1.0 wt.% preservatives 0.01 to 1.0 wt.% kaolin Up to 0.01 wt.% Microsilicates Up to 0.01 wt.% Fibers Up to 0.01 wt.% * to 100% by weight

[0054] In a particularly preferred embodiment, the brushable surface plaster composition according to the invention is formed from the following components: Table 2 Limestone sands 50 to remaining quantity Water 10 to 30 wt.% Pigments (especially TiO2) 5.0 to 10.0 wt.% Talk 2.5 to 6.0 wt.% Surface additives 1.0 to 2.5 wt.% Microsilicates 1.0 to 2.5 wt.% Aluminum calcium oxide sulfate 0.01 to 4.00 wt.% Organic binder 0.01 to 1.0 wt.% Stabilizers 0.01 to 1.0 wt.% Fibers 0.01 to 1.0 wt.% Alkyd resin 0.01 to 1.0 wt.% Thickener 0.01 to 1.0 wt.% Abbinder regulator 0.01 to 1.0 wt.% Defoamer 0.01 to 1.0 wt.% Other additives Up to 0.01 wt.% * to 100% by weight

[0055] Another aspect of the present invention relates to a plaster system comprising a plaster primer and a brushable surface plaster, as described above. This plaster system is particularly distinguished by the fact that, with a single coat of primer and two to three coats of the brushable surface plaster, followed by smoothing, the joints of an underlying tile layer are completely concealed, and a very homogeneous surface is achieved. Furthermore, the application of the compositions is very simple and user-friendly.

[0056] In a particularly preferred embodiment of this aspect, the plaster system according to the invention is formed from the special plaster primer composition and brushable surface plaster composition specified above.

[0057] By means of the plaster primer compositions and brushable surface plaster compositions specified above, a surface structure with stable adhesion and high durability over long periods can be achieved by sequential application to a substrate of ceramic, glass, or mosaic tiles. Accordingly, the present invention relates in a further aspect to a coated surface, in particular in the form of a wall or floor surface, comprising a lower layer of glass, ceramic, or stoneware, on which a layer formed from a plaster primer composition as described above and at least one layer of a surface plaster composition as specified above is applied to the plaster primer composition, wherein the plaster primer composition and the surface plaster composition are in a hardened and / or dried form.

[0058] The substrate is preferably a tiled surface, in particular a surface made of ceramic, glass or mosaic tiles.

[0059] The surface structure formed by the surface plaster composition on the coated surface is not subject to any relevant limitations and can exhibit a variety of conceivable textures. For example, the surface can be rough if the brushable surface plaster composition is applied with a long-floor roller. The surface can also be medium-rough if applied with a short-floor roller, smooth if the surface was leveled with a screed after application, or have an organic appearance if the surface plaster composition was finished with a dampened paint roller after application.

[0060] With regard to the aspects described above, embodiments that are indicated as preferred are to be considered as being combined with other preferred embodiments as described and disclosed in the context of this description, even if the correspondingly combined features are not explicitly listed in combination due to the brevity required for this description.

[0061] The present invention is illustrated in more detail below using an exemplary embodiment: A plaster primer composition according to Table 1 was first applied to a substrate using a roller applicator and allowed to dry for 2 hours. Subsequently, several coats of a brushable surface plaster composition were also applied to the hardened primer composition using a roller applicator and allowed to dry. The resulting bond was characterized by good adhesion of the plaster to the ceramic tiles, which remained stable even after 50 temperature and humidity cycles in the drying oven. Impact and scratch tests showed no significant flaking of the surface. The mineral surface finish remained intact throughout the entire observation period, and only a slight loss of gloss was observed. The coordinated plaster primer composition and the brushable surface plaster composition proved to be durable in combination and demonstrated good system compatibility.The observations made in the laboratory were subsequently confirmed in practical testing (on the construction site). QUOTES INCLUDED IN THE DESCRIPTION

[0000] This list of documents cited by the applicant was automatically generated and is included solely for the reader's convenience. The list is not part of the German patent or utility model application. The DPMA accepts no liability for any errors or omissions. Cited patent literature

[0000] EP 2 059 571 B1

[0003] EP 2 998 367 A1

[0004] EP 4 389 719 A1

[0005] WO 2005 / 100279 A1

[0006]

Claims

[1] Plaster primer composition comprising - at least 50% by weight of a calcium carbonate filler; - 8 to 25 wt% of an acrylate binder containing carboxyl groups and silane groups; - a transition metal salt with at least divalent cations and - 10 to 25% by weight water. [2] Plaster primer composition according to claim 1, wherein the composition further comprises silicone, preferably in an amount in the range of 0.1 to 2.5 wt.%. [3] Plaster primer composition according to claim 1 or 2, wherein a zinc salt is included in the composition as a transition metal salt. [4] Plaster primer composition according to one of claims 1 to 3, wherein the composition further comprises a white pigment, preferably in the form of titanium dioxide, and more preferably in an amount in the range of 2.5 to 5 wt.%. [5] Plaster primer composition according to at least one of claims 1 to 4, wherein the composition further contains platelet-shaped talc, preferably in an amount of up to 5 wt.% and / or wherein the calcium carbonate filler contains calcium carbonate of different fineness of grinding. [6] Plaster primer composition according to at least one of claims 1 to 5, wherein the composition further comprises one or more additives selected from the group comprising thickeners, coalescing agents, stabilizers, emulsifiers, dispersing agents, preservatives, fibers, microsilicates and kaolin, preferably in an amount in the range of 8 wt.% or less and preferably up to 5 wt.% or less. [7] Brushable surface plaster composition comprising - at least 50% by weight of a calcium carbonate filler; - 1.5% by weight or less of organic binder; - 2.5 to 6 wt% talc; - 10 to 30 wt.% water. [8] Brushable surface plaster composition according to claim 7, wherein the organic binder is a mixture of vinyl acetate ethylene copolymer and an alkyd resin, preferably in a ratio in the range of 3:1 to 1:3 and further preferably in the range of 1:2 to 1:

1. [9] Brushable surface plaster composition according to claim 7 or 8, wherein the composition additionally comprises a polyurethane thickener, preferably in combination with one or more thickeners selected from the group comprising hydroxyethyl eclulose, xanthan gum, hectorite and acrylate thickeners, wherein the thickener is further preferably included in the surface plaster composition in a total amount of 1 wt.% or less based on the total weight of the surface plaster composition. [10] Brushable surface plaster composition according to at least one of claims 7 to 9, wherein the composition further comprises zinc oxide, preferably in an amount in the range of 0.25 to 1.0 wt.%, and / or CaOAl2O3CaSO4 × n H2O as a white pigment, preferably in an amount in the range of 1 to 5 wt.%. [11] Brushable surface plaster composition according to at least one of claims 7 to 10, wherein the composition is a biocide-free surface plaster composition. [12] Brushable surface plaster composition according to at least one of claims 7 to 11, wherein the composition additionally contains up to 1 wt.% hydrophobic microhollow spheres and / or up to 0.5 wt.% fibers, in particular in the form of cellulose fibers. [13] Brushable surface plaster composition according to at least one of claims 7 to 12, wherein the composition additionally contains at least one further additive selected from the group comprising surface additives, microsilicates, stabilizers, setting regulators, wetting and dispersing agents, film formers and defoamers, preferably wherein the total amount of the further additives contained in the surface plaster composition is 5 wt.% or less and preferably 3 wt.% or less. [14] Plaster system comprising a plaster primer composition according to any one of claims 1 to 6 and a brushable surface plaster composition according to any one of claims 7 to 13. [15] Coated surface, in particular in the form of a wall or floor surface, comprising a lower layer of glass, ceramic or stoneware, a layer of a plaster primer composition formed on this layer according to one of claims 1 to 6 and at least one layer of a surface plaster as specified in one of claims 7 to 13 applied to the plaster primer composition, wherein the plaster primer composition and the surface plaster are in hardened and / or dried form.