Pigmented ink receiving layer for decorative building board

Abstract

The present invention relates to a method for producing a coated building board comprising an ink-receiving layer, i) applying to at least a portion of a surface of a building board an aqueous coating composition comprising: a) 5 to 40% by mass of an acrylic polymer in the coating composition; b) 1 to 6% by weight of the coating composition of a molecular sieve; and c) 1 to 30% by mass of a pigment in the coating composition; ii) curing the coating composition; At least The present invention also relates to an aqueous composition for producing an ink-receiving layer comprising an acrylic polymer, a molecular sieve and a pigment, and the use thereof.

Description

[Technical field]

[0001] Technical Field The present invention relates to a pigmented ink-receiving layer for aqueous inks for the production of decorative building boards, and a method for producing a coated building board comprising a pigmented ink-receiving layer. More specifically, the present invention relates to an aqueous coating composition for producing a coated building board, comprising an acrylic polymer, a molecular sieve and a pigment. [Background technology]

[0002] 2. Background of the Invention For example, various decorative building boards can be colored with inkjet printing, which allows for efficient production and unique designs. Compared to solvent-based inks and UV inks, water-based inks can use pigments with high weather resistance, making them suitable for exterior wall applications and attracting attention. Another important advantage is that water-based inks are environmentally friendly.

[0003] On the other hand, it is difficult to perform aqueous inkjet printing because aqueous ink is more difficult to cure than solvent ink or UV ink. Therefore, aqueous ink is more likely to penetrate into the substrate, especially if the substrate is porous, and is more likely to spread over the surface if the substrate is non-porous. This results in a decrease in image quality.

[0004] In order to improve the color intensity of an image printed on a decorative building board with a water-based ink, JP 2007-154433 A proposes providing an ink-receiving layer on the surface of the building board. The ink-receiving layer is a water-based paint containing an extender pigment and a hygroscopic resin. JP 2007-167826 A describes the use of such a coating composition to reduce the ink consumption in inkjet printing. In order to suppress the penetration of ink into the ink-receiving layer and to stably fix the ink, JP 2015-051549 A proposes an ink-receiving layer containing polysiloxane.

[0005] Japanese Patent Application Laid-Open No. 2008-273055 discloses a coating composition for an ink-receiving layer, which contains 20 to 80% by mass of a mica filler based on the solid content of the coating composition in order to improve the durability of the coating layer.

[0006] JP 2008-063832 A provides a decorative building board that enhances the ink fixation to the ink-receiving layer and prevents the strength of the layer from decreasing. To achieve the desired effect, the ink-receiving layer contains a high aspect ratio filler having an aspect ratio of 3 to 70, and can be finely divided on the layer surface.

[0007] The coated building board usually comprises a sealing layer and a pigmented primer layer on the surface of the building board. Thus, the surface of the building board on which the aqueous coating composition is applied is formed by such a primer layer. The primer layer is used to provide a background color, especially when a pigment-free color imaging layer is subsequently applied. The building board usually consists of a sealing layer and a white primer layer. [Prior art documents] [Patent documents]

[0008] [Patent Document 1] JP 2007-154433 A [Patent Document 2] JP 2007-167826 A [Patent Document 3] JP 2015-051549 A [Patent Document 4] JP 2008-273055 A [Patent Document 5] JP 2008-063832 A Summary of the Invention [Problem to be solved by the invention]

[0009] The problem that the present invention aims to solve is to provide a building board that can be used as a substrate for high-quality images printed with water-based inkjet inks. In particular, the resolution, color strength, and image stability of the printed image are to be improved. To achieve these goals, it is necessary to reduce the penetration of the water-based ink into the building board to avoid low color strength, and to avoid color bleeding in order to achieve improved resolution of the printed pattern.

[0010] In general, the manufacturing process of a coated building board includes the following steps (1) to (10): (1) Spray coating the sealing layer; (2) Allow the sealing layer to dry; (3) spray coating a layer of pigmented primer; (4) Allow the primer layer to dry; (5) spray coating the ink receiving layer; (6) drying the ink-receiving layer; (7) Inkjet printing; (8) Dryness; (9) Spray coat the top coat; (10) Allow the top coat to dry.

[0011] For practical reasons (limited number of spray booths and spray coaters), very often between steps (4) and (5) the precoated building board has to be removed from the production line and set aside (stapled), the spray coater is loaded with the ink-receiving layer coating composition, and then the stapled precoated building board has to be further processed, which involves many additional steps. It is also an object of the present invention to simplify this production process. [Means for solving the problem]

[0012] Description of the invention This problem is solved by an ink-receiving layer (color imaging layer) that contains an acrylic polymer, a molecular sieve, and a pigment.

[0013] More specifically, the problem is solved by a method for producing a coated building board comprising an ink-receiving layer (color imaging layer), the method comprising at least: i) applying to at least a portion of the surface of a building board an aqueous coating composition comprising: a) 5 to 40% by weight of an acrylic polymer in the coating composition; b) 1 to 6% by weight of the coating composition of a molecular sieve; and c) 1 to 30% by weight of a pigment in the coating composition; forming a coating on at least a portion of a surface of a building board; ii) curing the coating composition.

[0014] This issue is a) 5 to 40% by weight of an acrylic polymer in the coating composition; b) 1 to 6% by weight of the coating composition of a molecular sieve; c) 1 to 30% by weight of a pigment in the coating composition. The problem is also solved by an aqueous coating composition comprising:

[0015] Preferably, the surface of the building board to which the aqueous coating composition is applied does not include a pigmented primer layer.

[0016] However, the surface of the building board to which the aqueous coating composition is applied preferably comprises a sealing layer.

[0017] By incorporating the pigment into the ink receiving layer, the pigmented primer layer is no longer necessary and the manufacturing process is simplified as follows: (1) Spray coating the sealing layer; (2) Allow the sealing layer to dry; (3) spray coating the ink receiving layer; (4) drying the ink-receiving layer; (5) Inkjet printing; (6) Dryness; (7) Spray coat the top coat; (8) Allow the top coat to dry.

[0018] Furthermore, there is no need for the additional steps of removing the precoated building board from the production line, setting it aside, reloading the spray coating machine with additional coating composition, and reloading the precoated board back into the production line for further processing. Thus, the manufacturing process is simpler.

[0019] The coated building board of the present invention is obtained by an aqueous coating composition comprising an acrylic polymer emulsion, a molecular sieve and a pigment, which can be cured on the surface of the building board.

[0020] The aqueous coating composition of the present invention comprises an acrylic polymer emulsion comprising an acrylic polymer a) obtained by free radical polymerization of an acrylic monomer composition, where the acrylic monomer is selected from the group consisting of acrylates, methacrylates, alkyl acrylates, alkyl methacrylates, hydroxyalkyl acrylates, hydroxyalkyl methacrylates, epoxyalkyl acrylates, epoxyalkyl methacrylates, acrylonitrile, methacrylonitrile, acrylamides, methacrylamides, acrylic acid and mixtures thereof, and optionally ethylenically unsaturated comonomers.

[0021] Preferred acrylic polymers a) are derived from monomers from the group consisting of acrylates, methacrylates, (C1-C4)-alkyl acrylates, (C1-C4)-alkyl methacrylates, acrylic acid and mixtures thereof, and optionally ethylenically unsaturated comonomers.

[0022] Preferred comonomers are selected from the group of the (C1-C6)-alkylenes, in particular ethylene, propylene and butylene, and styrene.

[0023] Acrylic polymer emulsions also include emulsions of acrylic silicone resins.

[0024] The acrylic monomer composition preferably comprises at least 50% by weight of an acrylic monomer and less than 50% by weight of an ethylenically unsaturated comonomer.

[0025] The content of the solid acrylic polymer a) in the acrylic emulsion is generally in the range of 20 to 75% by mass, preferably 30 to 70% by mass, and particularly preferably 30 to 60% by mass.

[0026] The water content of the acrylic polymer emulsion is generally from 25 to 80% by mass, preferably from 30 to 70% by mass, and particularly preferably from 40 to 70% by mass.

[0027] The aqueous coating composition of the present invention further comprises a molecular sieve b).

[0028] Molecular sieves are porous materials with pores of relatively uniform size. The pore size of molecular sieves is comparable to that of low molecules, so they cannot adsorb high molecules, as opposed to low molecules such as water. The pore size of molecular sieves is expressed in Å (angstroms) or nm (nanometers). Molecular sieves are classified into microporous materials with a pore size of less than 2 nm (20 Å), mesoporous materials with a pore size of 2-50 nm (20-500 Å), and macroporous materials with a pore size of more than 50 nm (500 Å). Macroporous materials with a pore size of more than 200 nm (2000 Å) are not considered molecular sieves in the sense of the present invention.

[0029] In order to achieve the desired effects of the present invention, the use of microporous molecular sieves is preferred. Preferred molecular sieves b) have a narrow pore size distribution, with at least 90% of the pores of the molecular sieve having a pore size of 0.1 nm to 2 nm, more preferably 0.2 nm to 0.8 nm.

[0030] The microporous molecular sieve may be selected, for example, from the group of aluminosilicate minerals (zeolites), phosphorus modified microporous zeolites, porous glass, activated carbon, and microporous clays such as montmorillonite.

[0031] Preferred molecular sieves b) are capable of adsorbing molecules having an effective diameter of 0.5 nm or less, such as water. Useful sieves are capable of adsorbing at least 5% by weight of water at 20° C., more preferably more than 10% by weight of water, relative to the weight of the molecular sieve.

[0032] Preferred microporous molecular sieves are selected from the group of zeolites, particularly preferred are 3 Å, 4 Å or 5 Å zeolites.

[0033] Suitable zeolites are those of the general formula (I) M n+ x / n ·[(AlO2) - x (SiO2) y ]·zH2O (I) where n is 1, 2, 3 or 4, preferably n is 1 or 2; M is selected from the group of monovalent, divalent, trivalent or tetravalent metals or mixtures thereof, preferably M is selected from the group of alkali metals, alkaline earth metals and mixtures thereof, most preferably metals from the group potassium, sodium, magnesium and calcium; x is between 1 and 10, preferably between 1 and 3; The ratio x / y in the zeolite of formula (I) is between 1 and 5, more preferably between 1 and 3, most preferably about 2, ie between 1.8 and 2.2.

[0034] The water content of zeolites can vary in a wide range. For example, water can be removed from zeolites by heating without destroying the structure of the zeolites. Conversely, zeolites can absorb water until the compound's capacity is exhausted. For example, dry zeolites of the preferred zeolite types (x and x / y in the range of 1-3) can adsorb up to 30% by weight of water compared to the weight of the zeolite. The water content z of zeolites of formula (I) typically ranges from 0 to 50, preferably from 1 to 30. For preferred zeolites, x ranges from 1 to 3, the x / y ratio ranges from 1 to 3, and z is typically less than 10.

[0035] The most preferred molecular sieves b) of the zeolite type are 3 Å, 4 Å or 5 Å zeolite sieves.

[0036] Typical chemical formula for 3Å sieves x'K2O·x''Na2O·Al2O3·ySiO2·zH2O where x' and x'' are in the range of 0.3 to 0.7, and x' + x'' is 1; y is in the range of 1.8 to 2.2, preferably y is 2, and z is less than 8, and z is preferably in the range of 3 to 6, typically 4.5.

[0037] Typical chemical formula for 4Å sieve Na2O·Al2O3·ySiO2·zH2O where y is in the range of 1.8 to 2.2, preferably y is 2, and z is less than 8, and z is preferably in the range of 3 to 6, typically 4.5.

[0038] Typical chemical formula for 5Å sieves x'CaO·x''Na2O·Al2O3·ySiO2·zH2O where x' ranges from 0.6 to 0.8; x'' is in the range of 0.2 to 0.4. x'+x'' is 1; y is in the range of 1.8 to 2.2, preferably y is 2, and z is less than 8, and z is preferably in the range of 3 to 6, typically 4.5.

[0039] A wide variety of microporous molecular sieves are commercially available, including 3Å, 4Å, and 5Å zeolites. However, 4Å sieves can be produced by mixing aqueous solutions of sodium silicate and sodium aluminate at 80 °C. The sieve is then activated by calcination at 400 °C. 3Å and 5Å sieves can be produced from the 4Å sieve by cation exchange of sodium with potassium (for 3Å sieves) or sodium with calcium (for 5Å sieves).

[0040] An example of a mesoporous molecular sieve is silicon dioxide. An example of a macroporous molecular sieve is a porous silica compound having a pore size of 200 to 1000 Å.

[0041] The size of the pores in a molecular sieve depends on the size of the lattice of the material itself, and is determined primarily by the size of the cations. The structures of a wide variety of zeolites, including the size of their channels, are summarized in the ''Atlas of Zeolite Framework Types'' (Baerlocher et al.. Elsevier. Sixth Revised Edition. 2007).

[0042] Preferred molecular sieves b) are capable of adsorbing molecules having an effective diameter of 0.5 nm or less, such as water. Useful sieves are capable of adsorbing at least 5% by weight of water, more preferably 10% by weight or more of water, compared to the weight of the molecular sieve.

[0043] The molecular sieve is preferably applied to the aqueous coating composition in the form of a powder. Preferred powders have an average particle size in the range of 0.1 μm to 250 μm, preferably an average particle size of 1 μm to 50 μm. It is preferred that at least 80%, especially at least 90%, of the particles have an average particle size within this range.

[0044] The particle size distribution of the molecular sieve particles can be measured by laser diffraction analysis. The average particle size can be determined by laser light scattering method by "Mie scattering theory" evaluation, for example using Horiba LA 940 or Malvern Mastersizer 3000. For particles with axes of different lengths, for example particles with ellipsoid or disc shape, the largest axis determines the average particle size. The particles of the present invention preferably have a narrow particle size distribution with a Gaussian shape. Preferably, the standard deviation of the particle size distribution is 10% to 120% of the average particle size. More preferably, the standard deviation is 20% to 90%.

[0045] The aqueous coating composition preferably contains 2 to 6 mass %, more preferably 2 to 5.5 mass %, and particularly preferably 3 to 5 mass % of molecular sieves. The amount of acrylic polymer (solid content) is preferably in the range of 10 to 35 mass %, more preferably in the range of 10 to 30 mass %, and particularly preferably in the range of 15 to 30 mass %, based on the total weight of the aqueous coating composition.

[0046] The aqueous coating composition of the invention further comprises a pigment c). The pigment can be selected from inorganic or organic pigments. Pigments that can be used are all pigments known to the skilled artisan for emulsion paints. Preferred pigments are titanium dioxide, preferably in rutile form, barium sulfate, zinc oxide, zinc sulfide, basic lead carbonate, antimony trioxide and lithopone (zinc sulfide and barium sulfate). However, the aqueous formulation can also contain color pigments, such as iron oxide, carbon black, graphite, luminescent pigments, zinc yellow, zinc green, ultramarine, manganese black, antimony black or manganese violet. Organic pigments are, for example, azo dyes, quinacridones, phthalocyanines, isoindolinones, sepia, gamboge, indigo, anthraquinoid, indigoid dyes, dioxazines, metal complex pigments, etc.

[0047] The most preferred pigments are titanium dioxide, zinc oxide, zinc sulfide, barium sulfate, white lead (lead hydroxycarbonate, 2PbCO3·Pb(OH)2), white antimony (antimony(III) oxide, Sb2O3), calcium carbonate (chalk) and lithopone. Especially preferred is titanium dioxide.

[0048] The pigment is added to the aqueous coating composition in an amount of 1 to 30% by mass, preferably 2.5 to 25% by mass, and more preferably 5 to 25% by mass, based on the total weight of the aqueous coating composition.

[0049] The aqueous coating composition may contain any additive. Examples of useful additives include defoamers, dispersants, wetting agents, thickeners, film formers, matting agents, neutralizing agents, biocides and humectants. The additives can be applied to the aqueous coating composition containing the acrylic polymer emulsion or emulsion.

[0050] Customary additives include antifoam additives d), such as fatty acid alkyl ester alkoxylates, silicone oils, organopolysiloxanes, such as polydimethylsiloxanes, polyether-modified polysiloxanes, silanized silicas, paraffins, including paraffin oils, polyethers, such as polyethylene glycols, polypropylene glycols or EO / PO copolymers, and mixtures thereof.

[0051] Antifoam additives d) are, for example, fatty acid alkyl ester alkoxylates, silicone oils, organopolysiloxanes, such as polydimethylsiloxanes, polyether-modified polysiloxanes, silanized silicas, paraffins, including paraffin oils, polyethers, such as polyethylene glycols, polypropylene glycols or EO / PO copolymers, alkyne glycols, such as acetylenic diols, and mixtures thereof.

[0052] The defoamer d) is usually used in an amount of 0.1 to 2% by weight, based on the total amount of the aqueous coating composition.

[0053] Customary additives further include dispersants or wetting agents e), such as sodium, potassium or ammonium polyphosphates, alkali metal or ammonium salts of polyacrylic and polymaleic acids, styrene-maleic anhydride copolymers, polyphosphonates, aminoalcohols, such as 2-amino-2-methylpropanol. The dispersants or wetting agents are preferably used in an amount of up to 2% by weight, based on the total weight of the aqueous coating composition.

[0054] Usually, the acrylic polymer of the acrylic polymer emulsion is self-emulsifying. Therefore, the amount of additional dispersant may be small. The content of the dispersant in the aqueous coating composition is usually in the range of 0.1 to 2 mass %, preferably 0.1 to 1 mass %, based on the total weight of the aqueous coating composition.

[0055] The matting agent f) may be present in the aqueous coating composition in an amount of 0.1 to 15% by weight, based on the total weight of the coating composition. A content of matting agent of 2 to 15% by weight is preferred. Suitable matting agents are silicon dioxide, waxes and polysaccharides such as cellulose.

[0056] Preferred aqueous coating compositions contain one or more matting agents f) Preferably, the matting agent comprises at least one of silicon dioxide and a polysaccharide such as cellulose, in particular both.

[0057] Suitable film formers g) are, for example, polyvinylpyrrolidone, glycol ethers or glycol esters or combinations thereof.Examples of glycol ethers are ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monopropyl ether, ethylene glycol monoisopropyl ether, ethylene glycol monobutyl ether, ethylene glycol monophenyl ether, ethylene glycol monohexyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol mono-n-butyl ether, diethylene glycol mono-n-hexyl ether, propylene glycol monomethyl ether, propylene glycol monoethyl ether, propylene glycol monobutyl ether, propylene glycol monohexyl ether, polyethylene glycol ether, polypropylene glycol ether, ethylene glycol dimethyl ether, ethylene glycol diethyl ether and ethylene glycol dibutyl ether.Examples of glycol esters are, for example, ethylene glycol methyl ether acetate, ethylene glycol monoethyl ether acetate, ethylene glycol monobutyl ether acetate and propylene glycol methyl ether acetate.

[0058] The content of the film-forming additive g) is typically 0.1 to 10% by weight, based on the total weight of the aqueous coating composition. An amount in the range of 0.5 to 5% by weight is preferred.

[0059] Preferred aqueous coating compositions contain one or more film formers g).

[0060] Thickeners h) which can be used in the aqueous coating compositions are cellulose derivatives, such as methylcellulose, hydroxyethylcellulose, carboxymethylcellulose, also casein, gum arabic, starch, sodium alginate, polyvinyl alcohol, polyvinylpyrrolidone, styrene / maleic anhydride polymers, polyether urethanes, which can be hydrophilically modified, hydrophobically modified acrylic acid copolymers (HASE), sodium polyacrylates, organosilicones, and polyether polyols.

[0061] Water-soluble copolymers based on acrylic acid and (meth)acrylic acid also have thickening properties and are suitable, such as acrylic acid / acrylamide and (meth)acrylic acid / acrylic acid ester copolymers.

[0062] Inorganic thickeners such as bentonite may also be used.

[0063] Particular preference is given to using thickeners from the group of acrylic polymers and polyurethanes.

[0064] The amount of thickener h) based on the total weight of the coating composition is typically 0.1 to 2% by weight.

[0065] Further conventional additives are biocides i). Suitable biocides are, for example, 5-chloro-2-methyl-4-isothiazolin-3-one, 2-methyl-4-isothiazolin-3-one and Bromopol (2-bromo-2-nitro-1.3-propanediol, CAS number: 52-51-7). The biocides are generally present in an amount of 0.05 to 1% by weight, preferably 0.05 to 0.5% by weight.

[0066] For some applications, it is desirable to adjust the pH value of the aqueous coating composition. To adjust the pH value, common neutralizing agents j) can be used. Examples of neutralizing agents are sodium hydroxide, potassium hydroxide, or amine derivatives. For most applications, a pH value in the range of 7 to 11 is desired. The neutralizing agent is added to the coating composition until the desired pH value is reached. The neutralizing agent is usually present in an amount of 0.05 to 1% by weight.

[0067] The aqueous coating composition optionally comprises one or more humectants k). The humectants may be part of the additive composition. The amount of humectant is typically 0.1-5% by weight, preferably 0.5-5% by weight, based on the total weight of the coating composition.

[0068] Suitable are water-miscible humectants such as methanol, ethanol, propanol, butanol, benzyl alcohol, ethylene glycol, di-ethylene glycol, propylene glycol, di-propylene glycol, glycerol, polyethylene glycol, polypropylene glycol, and the mono- or di-methyl ethers of ethylene glycol or propylene glycol.

[0069] Preferred aqueous coating compositions contain one or more humectants k), such as 1,2-propanediol.

[0070] Particularly preferred aqueous coating compositions comprise, in addition to the acrylic polymer a), the molecular sieve b) and the pigment c), at least a matting agent e), at least a film-forming agent g) and at least one humectant k), preferably in the amounts specified above.

[0071] Molecular sieves can be added to acrylic polymer emulsions to obtain aqueous coating compositions. The molecular sieves can simply be incorporated into the acrylic polymer emulsion by stirring until the sieves are completely dispersed. Additives and pigments can usually be added stepwise under stirring.

[0072] In addition to the water already present in the acrylic polymer emulsion, additional water can be added to the aqueous coating composition if appropriate. However, the total water content in the coating composition should not exceed 75% by weight, and is generally between 30 and 75% by weight. Preferably, the total water content of the aqueous coating composition of the present invention is in the range of 35 to 65% by weight, in particular 40 to 60% by weight.

[0073] In general, the aqueous coating composition of the present invention comprises: a) 5 to 40% by mass of an acrylic polymer; b) 1 to 6% by weight of a molecular sieve; c) 1 to 30% by weight of a pigment; d) optionally 0 to 2% by weight of an antifoaming agent; e) optionally 0 to 2% by weight of a dispersing or wetting agent, f) optionally 0 to 15% by weight of a matting agent; g) optionally 0 to 10% by weight of a film former; h) optionally 0 to 2% by weight of a thickener; i) optionally 0 to 1% by weight of a biocide, j) optionally 0 to 1% by weight of a neutralizing agent, and k) optionally 0-5% by weight of a humectant;

[0074] A preferred aqueous coating composition of the present invention comprises: a) 10 to 35% by mass of an acrylic polymer; b) 2 to 5.5% by weight of a molecular sieve; c) 2.5 to 25% by weight of a pigment; d) 0.1 to 2% by mass of an antifoaming agent; e) 0.1 to 2% by weight of a dispersing or wetting agent; f) 0.1 to 15% by mass of a matting agent; g) 0.1 to 10% by weight of a film former; h) 0.1 to 2% by mass of a thickener; i) 0.05 to 1% by weight of a biocide; j) 0.05 to 1% by weight of a neutralizing agent, and k) 0.1 to 5% by weight of a humectant.

[0075] Particularly preferred aqueous coating compositions of the present invention include: a) 10 to 30% by mass of an acrylic polymer; b) 2 to 5% by weight of a molecular sieve; c) 5 to 25% by weight of a pigment; d) 0.1 to 1% by mass of an antifoaming agent; e) 0.1 to 1% by weight of a dispersing or wetting agent, f) 2 to 15% by weight of a matting agent; g) 0.5 to 5% by weight of a film former; h) 0.1 to 2% by mass of a thickener; i) 0.05 to 0.5% by weight of a biocide; j) 0.05 to 1% by weight of a neutralizing agent, and k) 0.5 to 5% by weight of a humectant.

[0076] The aqueous coating composition can be applied to the surface of the building board by means of a spraying device, such as a spray gun, or the coating composition can be brushed onto the surface or applied with a doctor blade.

[0077] Typically, the aqueous coating composition has a coating density of 10 g / m 2 ~300g / m 2 , preferably 20 g / m 2 ~200g / m 2 It is applied in the range of.

[0078] The aqueous coating composition applied to the building board is then cured to obtain a color imaging layer (ink-receiving layer) on the surface of the building board. Curing can be achieved by drying the coating at a temperature of 70°C to 300°C for 1 minute to 1 hour. The coating is sufficiently dry if the resulting color imaging layer can take up the aqueous ink. The coated building board may be dried in an oven. It is preferable to dry at a temperature of 150°C to 250°C for 2 minutes to 150 minutes.

[0079] The thickness of the color imaging layer on the building board is usually between 5 μm and 500 μm, preferably between 10 μm and 200 μm.

[0080] As long as the color imaging layer can be sufficiently fixed on the surface, various building materials can be used as the building board. For example, cement boards, gypsum boards, ceramic boards, metal boards, wood boards, polymer resin boards, etc. are suitable. Preferably, building boards containing cement or gypsum are used. These boards have good adhesion of the color imaging layer. Also suitable are fiber-reinforced building boards, especially cement boards containing glass fiber or polymer fiber.

[0081] The coated building board preferably includes a sealing layer. The sealing layer can be applied to the surface of the building board. The surface of the building board to which the aqueous coating composition is applied is thus formed by such a layer. Typical sealers are water-based or solvent-based acrylic resins, epoxy / urethane systems, silanes, silicates, siliconates, siloxanes, etc.

[0082] A further embodiment of the present invention is a coated building board comprising a color imaging layer (ink-receiving layer) of the cured coating composition as described above.

[0083] The coated building board is particularly useful for printing color patterns or images on the color imaging layer with water-based inks. The water-based inks can be printed directly on the color imaging layer, for example by inkjet printing. The printed patterns can be easily personalized. The coated building board is suitable for DIY (Do it yourself) printing.

[0084] When water-based ink is applied to the color imaging layer, the ink is quickly fixed and color bleeding is greatly reduced. The resolution of the printed pattern or image is improved. In addition, high color strength can be obtained due to the fast penetration of water-based ink into the color imaging layer.

[0085] Without being bound by any theory, the desired effect is achieved by facilitating the adsorption of water by the molecular sieve from the aqueous ink while at the same time significantly retarding the penetration of colorants and pigments provided as components of the aqueous ink into the color imaging layer, thereby resulting in low color bleed and high color strength.

[0086] The color imaging layer is particularly useful for applying aqueous inks having a water content of 40-70% by weight and a pigment content in the range of 0.1-20% by weight. Typical aqueous inks further include up to 40% by weight of a humectant, such as glycerin, propylene glycol, up to 30% by weight of a surfactant, such as polyoxyethylene alkyl ether, and a pH adjuster. Optionally, the aqueous ink can include up to 20% by weight of an acrylic resin.

[0087] Thus, a further embodiment of the present invention is the use of a building board comprising a color imaging layer as described herein as a substrate for inkjet printing with water-based inks.

[0088] The present invention also relates to a coated building board comprising a color imaging layer of the cured coating composition described herein on at least a portion of a surface of the building board, preferably the building board being a cement board, a gypsum board, a ceramic board, a metal board, a wood board, a polymer resin board, a calcium silicate board, a diatomaceous earth board, or a polystyrene board.

[0089] The present invention also relates to the use of an aqueous coating composition as described herein for producing a color imaging layer (ink-receiving layer) on a coated building board used as a substrate for ink-jet printing with aqueous inks. Preferably, and most advantageously, the aqueous coating composition is applied to a surface of the building board that does not contain a pigmented primer layer.

[0090] example Examples 1-5 The ingredients used to prepare the compositions of Examples 1 to 5 are summarized in Table 1 below.

[0091] [Table 1]

[0092] Example 1 30.1 parts by weight of acrylic emulsion (Mowilith DN 7070, Archroma Co. Ltd.), 15 parts by weight of titanium dioxide (Colanyl White TQ-CN, Clariant Chemicals Ltd.), 0.15 parts by weight of defoamer (TEGO FOAMEX 810), 1.35 parts by weight of humectant (1,2-propanediol), 1.13 parts by weight of silicon dioxide (ACEMATT TS 100; matting agent), 4.72 parts by weight of molecular sieves (SYLOSIV A 3, W.R. Grace & Co.), 2.71 parts by weight of wax powder (Ceridust 8090 VITA, Clariant Chemicals Ltd.; matting agent), 5.83 parts by weight of silicon dioxide (SYLOID W, W.R. Grace & Co. 300; matting agent) and 1.85 parts by weight of deionized water were mixed with a disperser at a shear rate of 1300 rpm for 60 minutes.

[0093] Next, a mixture of 15.05 parts by weight of acrylic emulsion (Mowilith DN 7070, from Archroma Co Ltd), 18.05 parts by weight of deionized water and 2.26 parts by weight of film former, dipropylene glycol n-butyl ether (DPnB, from Dow Chemical) 0.15 parts by weight of defoamer (Surfynol DF-110D, from Evonik), 0.20 parts by weight of biocide (Acticide LA 0614, from Thor Chemie), 0.15 parts by weight of neutralizer 2-amino-2-methyl-1-propyl alcohol (AMP 95 from Dow Chemical), and a mixture of 0.50 parts by weight of deionized water and 0.50 parts by weight of thickener (Acrysol TT-615 from Dow Chemical) was mixed at a shear rate of 1300 rpm for 30 minutes until completely dispersed to produce a coating composition.

[0094] The composition of Example 1 is summarized in Table 2 below.

[0095] [Table 2]

[0096] Coating compositions according to Examples 2 to 5 were prepared accordingly. The ingredients contained in the compositions of Examples 1 to 5 are summarized in Table 3 below.

[0097] [Table 3]

[0098] The coating composition was applied to a cement fiberboard at 150 g / m 3 Spray in an amount of 200 o C for 3 minutes to form a color imaging layer. The cement fiberboard was pretreated with a sealing coating.

[0099] Characterization: State inside the container: No hard blocks and uniform after mixing. Evaluation criteria A: I have the aptitude. B: Not suitable

[0100] Freeze-thaw stability: According to GB / T9268-2008: Place the sample tank in a freezer and keep the temperature at -5±2°C, with at least 25mm gap between adjacent sample tanks and between the sample tank and the tank wall. The sample tank is placed in the freezer for 18 hours, then taken out and cooled at 23±2°C for 6 hours as one cycle, and there is no deterioration after 3 cycles, such as hard block, agglomeration, water stratification, etc. Evaluation criteria A: I have the aptitude. B: Not suitable

[0101] Drying time: According to GB / T1728-1979 standard, Table B method, lightly touch the surface of the coating with your finger. If the surface feels sticky when you touch it with your finger, but the paint does not stick to your finger, the surface of the coating is considered dry. Evaluation criteria Within 2 hours of surface drying.

[0102] Adhesion: According to GB / T9286 standard: Use a single edge cutter to cut 3 parallel passes along the parallel and perpendicular directions of the long side of the plate. The interval between each pass is 3mm, and the grid number is 4. Carry out tape tear test. Observe the test surface, there is peeling of coating at the intersection of the notch / or along the edge of the notch. If the affected cut area is obviously less than 15%, the test result grade is ≦2.

[0103] Evaluation criteria (0) The edges of the cut are perfectly smooth and none of the squares in the lattice are separated. (1) Small pieces of coating are removed at the intersections of cuts. Less than 5% of the cross-cut area is affected. (2) The coating is missing along edges and / or at the intersections of cuts. More than 5% but not more than 15% of the cross-cut area is affected. (3) Large ribbons of coating loss along the edges of the cut, either partially or completely, and / or partial or complete loss of coating in different portions of a square, affecting more than 15 percent, but not more than 35 percent, of the cross-cut area. (4) The coating has been partially or completely removed in large ribbons along the edges of the cut and / or the coating has been partially or completely removed in different portions of a square, affecting more than 35 percent but not more than 65 percent of the cross-cut area. (5) Peeling that cannot be classified even under category 4.

[0104] Color Performance: The resulting building board was placed under an inkjet device loaded with four water-based inks: cyan, magenta, yellow, and black. The ejection and suspension of the four inks from the nozzles are individually controlled by a control device. Inkjet printing was performed by printing a pre-designed image directly onto the building board. It was then dried in an oven at a temperature of 200°C for 3 minutes to harden the imaging layer. Preferably, a transparent topcoat is sprayed on the hardened imaging layer for protection. The resulting image is evaluated visually.

[0105] Evaluation criteria Color intensity from 1 (very low) to 5 (high) Resolution ranges from 1 (very blurry, dull, image is difficult to recognize) to 5 (image is clean and sharp).

[0106] The performance evaluation results are summarized in Table 4 below.

[0107] [Table 4]

Claims

1. 1. A method for producing a coated building board comprising an ink-receiving layer, the method comprising: i) applying to at least a portion of a surface of a building board an aqueous coating composition comprising: a) 5 to 40% by weight of the coating composition of an acrylic polymer; b) 1 to 6% by weight of said coating composition of a molecular sieve; and c) 1 to 30% by weight of the coating composition of a pigment; ii) curing the coating composition; The method includes at least the steps of:

2. The method of claim 1 , wherein the surface of the building board to which the aqueous coating composition is applied does not include a pigmented primer layer.

3. The method according to claim 1 or 2, wherein the surface of the building board to which the aqueous coating composition is applied comprises a sealing layer.

4. The process according to any one of claims 1 to 3, wherein the molecular sieve is a microporous molecular sieve, preferably selected from the group consisting of zeolites.

5. A method according to any one of claims 1 to 4, wherein at least 90% of the pores of the molecular sieve have a pore size between 0.1 nm and 2 nm, preferably the molecular sieve is a zeolite of 3 Å, 4 Å or 5 Å.

6. 6. The method of any one of claims 1 to 5, wherein the acrylic polymer comprises an acrylic polymer obtained by free radical polymerization of an acrylic monomer composition, wherein the acrylic monomer is selected from the group consisting of acrylates, methacrylates, alkyl acrylates, alkyl methacrylates, hydroxyalkyl acrylates, hydroxyalkyl methacrylates, epoxyalkyl acrylates, epoxyalkyl methacrylates, acrylonitrile, methacrylonitrile, acrylamides, methacrylamides, acrylic acid and mixtures thereof, and optionally an ethylenically unsaturated comonomer.

7. The method according to any one of claims 1 to 6, wherein the pigment is selected from the group consisting of titanium dioxide, zinc oxide, zinc sulfide, barium sulfate, white lead, white antimony, calcium carbonate and lithopone.

8. 8. The method of any one of claims 1 to 7, wherein the aqueous coating composition comprises at least one additive selected from the group consisting of film formers, dispersants, thickeners, defoamers, neutralizing agents, biocides, matting agents and humectants.

9. The method of any one of claims 1 to 8, wherein the aqueous coating composition comprises a matting agent.

10. 10. The method of claim 9, wherein the matting agent comprises at least one of silicon dioxide and wax powder.

11. The method of any one of claims 1 to 10, wherein the aqueous coating composition comprises a humectant.

12. The method of any one of claims 1 to 11, wherein the aqueous coating composition comprises a film former.

13. a) 5 to 40% by weight of an acrylic polymer; b) 1 to 6% by weight of a molecular sieve, and c) 1 to 30% by weight of a pigment The aqueous coating composition of any one of claims 1 to 12, comprising:

14. a) 5 to 40% by weight of an acrylic polymer; b) 1 to 6% by weight of a molecular sieve; c) 1 to 30% by weight of a pigment; d) optionally 0 to 2% by weight of an antifoaming agent; e) optionally 0 to 2% by weight of a dispersing or wetting agent; f) optionally 0 to 15% by weight of a matting agent, g) optionally 0 to 10% by weight of a film former; h) optionally 0 to 2% by weight of a thickener; i) optionally 0 to 1% by weight of a biocide, j) optionally 0 to 1% by weight of a neutralizing agent, and k) optionally 0 to 5% by weight of a humectant 14. The aqueous coating composition of claim 13, comprising:

15. a) 10 to 35% by weight of an acrylic polymer; b) 2 to 5.5% by weight of a molecular sieve; c) 2.5 to 25% by weight of a pigment; d) 0.1 to 2% by weight of an antifoaming agent; e) 0.1 to 2% by weight of a dispersing or wetting agent; f) 0.1 to 15% by weight of a matting agent; g) 0.1 to 10% by weight of a film former; h) 0.1 to 2% by weight of a thickener; i) 0.05 to 1% by weight of a biocide; j) 0.05 to 1% by weight of a neutralizing agent, and k) 0.1 to 5% by weight of a humectant 15. The aqueous coating composition of claim 14, comprising:

16. A coated building board comprising on at least a part of the surface thereof an ink-receiving layer of a cured coating composition according to any one of claims 1 to 15.

17. 17. The coated building board of claim 16, wherein the building board is a cement board, a gypsum board, a ceramic board, a metal board, a wood board, a polymer resin board, a calcium silicate board, a diatomaceous earth board, and a polystyrene board.

18. 18. Use of a building board according to any one of claims 16 and 17 as a substrate for ink-jet printing with water-based inks.

19. Use of the aqueous coating composition according to one of claims 1 to 15 for producing an ink-receiving layer on a building board which is used as a substrate for ink-jet printing with aqueous inks.

20. 20. The use according to claim 19, wherein the aqueous coating composition is applied to a surface of a building board that does not comprise a pigmented primer layer.

Images