JP2008073602A - Building plate - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a building plate having a clear layer formed of water-based clear paint after ink jet coating with the water-color ink, suppressing water-color ink from moving to the clear layer and preventing a design pattern from being stained. <P>SOLUTION: The building plate is formed by covering an ink-jet surface coated with the clear layer, after a substrate 1 is ink-jet coated with the water-color ink. The clear layer is formed of the water-based clear paint containing aggregate. Since the flowability of the clear paint after coating is decreased by the aggregate in the course of forming the clear layer, the movement of the water-color ink to the clear layer is suppressed, the design pattern formed by the ink jet coating is prevented from being stained, thus enabling a development of a clear design pattern and an improvement in the weather resistance of the building plate. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a building board used as an exterior material or the like that has been subjected to inkjet coating.

  Cement-based building boards are widely used as building boards used as exterior materials such as outer wall materials, roofing materials and roofing materials. Since such a building board bears the formation of the external appearance of a building, technical examination is added about the surface decoration which implement | achieves various designs. For example, a wet sheet obtained by molding a cement-based molding material by papermaking, extrusion molding, cast molding, etc. is cured and cured, and the resulting inorganic plate is used as a base material, and this is generally coated. ing.

  As one method of coating, recently, inkjet coating has been conceived in which a coating is sprayed from an inkjet nozzle head in synchronization with the substrate transport speed toward the surface of the substrate transported on a conveyor. Such ink-jet coating enables local and position-controlled coating as compared with a coating roll or the like that has been generally used so far. Therefore, there is an advantage that a building board coated with a high design with a natural texture can be manufactured by expressing dark and light (see Patent Document 1).

By such ink-jet coating, for example, with respect to the base material on which the joints are formed, the portion where the joints are formed is not applied, or the joints are formed and the joints are not formed. Brick-like or tile-like building boards can be obtained by painting the wood in different colors.
JP 2004-17007 A

  When performing ink jet coating as described above, for example, an ink receiving layer (ink receiving layer) is formed on a substrate such as an inorganic plate, and the ink applied during ink jet coating is applied to the ink receiving layer. Fixing without bleeding is performed, and then an appropriate clear paint is applied to the surface of the ink receiving layer to form a clear layer for protection.

  By the way, as an ink used for the inkjet coating, a water-based ink has been widely used from the viewpoint of developing a vivid design pattern and preventing deterioration of the working environment, and also in the case of forming a clear layer. It is required to use a water-based clear paint to prevent the working environment from deteriorating.

  However, since water-based ink and water-based clear paint have high affinity, if water-based clear paint is applied after ink-jet coating, the water-based ink moves to the clear paint, and the design pattern due to ink-jet coating is blurred. was there. In addition, when the water-based ink bleeds as described above, the water-based ink printed in a dot shape spreads in the horizontal direction, and the thickness of the water-based ink layer becomes thin, which causes a problem that the weather resistance is lowered. It was something that would end up.

  The present invention has been made in view of the above points, and is an architectural board in which a clear layer formed of a water-based clear paint is formed after inkjet coating using a water-based ink. An object of the present invention is to provide a building board that can suppress movement to a clear layer and prevent bleeding in a design pattern.

  A building board according to claim 1 is a building board in which a base plate 1 is coated with a water-based ink and then coated with a clear layer, and the clear layer is an aggregate. It is formed with the water-based clear coating material containing this.

  The invention according to claim 2 is characterized in that, in claim 1, the aggregate is acrylic resin beads having an average particle diameter of 10 to 50 μm.

  The invention according to claim 3 is characterized in that, in claim 1 or 2, the aggregate is calcium carbonate fine particles.

  According to a fourth aspect of the present invention, in any one of the first to third aspects, the aggregate is silica fine particles.

  The invention according to claim 5 is characterized in that, in any one of claims 1 to 4, an inorganic paint layer and a photocatalyst layer are sequentially laminated on the clear layer.

  According to the first aspect of the invention, the fluidity after painting of the clear paint is reduced by the aggregate during the formation of the clear layer, and the aggregate serves as a barrier to the diffusion of the water-based ink. The movement of the water-based ink to the applied clear paint will be suppressed, and it is possible to prevent bleeding from occurring in the design pattern formed by inkjet coating, and it is possible to express a clear design pattern Further, it is possible to prevent the water-based ink layer from being thinned due to bleeding of the water-based ink applied in the form of dots, thereby improving the weather resistance of the building board.

  Further, according to the invention according to claim 2, the acrylic resin beads can prevent the bleeding of the water-based ink and can reduce the gloss of the clear coating film to express a deep design pattern. Since the system beads have low water absorption and excellent acid resistance, the deterioration of the weather resistance of the coating film due to the addition of aggregates can be suppressed.

  Further, according to the invention of claim 3, the gloss of the clear coating film can be reduced and the deep design pattern can be expressed while preventing the water-based ink from bleeding with the calcium carbonate fine particles.

  Further, according to the invention of claim 4, it is possible to develop a deep design pattern by reducing the gloss of the clear coating film while preventing bleeding of the water-based ink by the silica fine particles.

  Moreover, according to the invention which concerns on Claim 5, the weather resistance and antifouling property of a building board can be improved further.

  Hereinafter, the best mode for carrying out the present invention will be described.

  As the base material 1 of the building board, an appropriate material such as an inorganic base material or a metal siding material can be used.

  When an inorganic base material is used as the base material 1, a wet sheet (green sheet) formed from a cement-based molding material mainly composed of cement and reinforcing fibers can be used for the production. This wet sheet is obtained by making paper by various types of paper making methods such as a long mesh type and a round net type, using a cement-based aqueous slurry as a cement-based molding material, or by extrusion molding. Examples of the cement-based molding material include hydraulic cement components of 30 to 95% by mass, fillers such as silica, silica powder, and fly ash 2 to 60% by mass, and reinforcing fibers such as pulp 3 to 10% by mass. The slurry consists of solid content, and a slurry having a ratio of about 40 to 100 parts by mass of water with respect to 100 parts by mass of the solids can be used. In addition, as a cement component, what adjusted composition suitably, such as normal Portland cement and blast furnace cement, can be used. As the reinforcing fiber pulp, softwood pulp, hardwood pulp, or a mixture thereof can be used. An inorganic base material can be obtained by curing and curing the wet sheet.

  Curing and curing of the inorganic base material can be performed by an appropriate method, but it is desirable to perform autoclave curing, and the temperature at that time is preferably 140 ° C. or higher. In practice, it is desirable that the curing is a two-stage curing of an autoclave curing and a pre-acceleration curing preceding this, that is, a pre-curing in which steam is added for heating. Thereby, the strength of the inorganic base material is improved, and the structure and performance are made uniform.

  During this curing, it is desirable to apply a sealer to the surface of the wet sheet before curing. By applying this sealer, it is possible to prevent the occurrence of efflorescence during curing, and the coating film of the sealer exhibits water resistance, so that the water resistance of the building board can be improved. .

  The sealer is not particularly limited, and for example, an aqueous resin emulsion such as acrylic, vinyl acetate, epoxy, chlorinated rubber, urethane, silicon, or fluorine can be used.

  Also, in such a sealer, inorganic particles such as heavy calcium carbonate, precipitated calcium carbonate, face forest, bentonite, sericite, dolomite, talc, clay, aluminum oxide, magnesium oxide, diatomaceous earth can be mixed. it can.

  And, such a sealer can be applied to the surface of the wet sheet and heated to form a film of the sealer.

  Such sealer coating is performed before curing, but when performing pre-acceleration curing as described above, it is preferable to apply the sealer after pre-acceleration curing and then perform autoclave curing. The frost damage resistance and dimensional stability of the plate can be improved.

  The base material 1 (inorganic base material) obtained by such curing is subjected to a drying process or a cutting process as necessary.

  Further, when a metal siding material is used as the base material 1, an appropriate primer, enamel paint, or the like can be applied to one surface of the base material 1.

  An ink receiving layer (ink receiving layer) is formed on the surface of the base material 1 thus obtained on the surface of a sealer coating or the like. The ink receiving layer has a function of fixing the ink applied at the time of inkjet coating without bleeding and has a property of absorbing ink, for example, forms a porous layer having water absorption. As the composition for forming the ink receiving layer (receiving layer forming composition), it is preferable to use an aqueous one.

As the receiving layer forming composition, an acrylic resin paint based on an acrylic emulsion or an acrylic silicon resin paint based on an acrylic silicon emulsion can be used. It is preferable that at least one of extender pigment and hygroscopic resin is blended in the receiving layer forming composition. As a result, it is possible to improve the fixing property of the ink, and it is possible to further suppress the occurrence of bleeding when forming a clear layer with a water-based clear paint as will be described later, and also improve the color developability. It is something that can be done. Here, silica, alumina, aluminum hydroxide, barium sulfate, porous silica, diatomaceous earth, or the like can be used as the extender pigment, and vinyl acetate, urethane polymer, acrylic polymer, polyvinyl alcohol can be used as the hygroscopic resin. Ink-absorbing polymers such as can be used. Moreover, when forming an ink receiving layer with a receiving layer forming composition, it is preferable to apply the receiving layer forming composition on the surface of the substrate 1 at a coating amount of 30 to 200 g / m ² · wet. In addition, application | coating of a receiving layer forming composition can be performed using a spray gun, a roll coater, a flow coater, a curtain coater, etc.

  Further, the pigment in the receiving layer forming composition means a colored pigment in addition to the above-mentioned extender pigment. As coloring pigments, inorganic pigments such as titanium oxide, petals, ochers, calcium carbonate, and composite metal oxides, and organic pigments such as carbon black, quinacridone, naphthol red, cyanine blue, cyanine green, Hansa yellow, and ultramarine blue are used. be able to. Only one type of pigment can be used, or two or more types can be used in combination. Among the pigments, it is preferable to use an inorganic pigment because the weather resistance of the building board can be improved. The particle size of the pigment is not particularly limited, but an average particle size of about 0.01 to 4 μm is preferable. The pigment can be dispersed by a usual method, and a dispersant, a dispersion aid, a thickener, a coupling agent, and the like can be used at that time.

  The pigment content (PWC) in the case where the extender pigment or the color pigment as described above is contained in the receiving layer forming composition is appropriately set, but can be in the range of 40 to 80%. Here, the pigment content is determined when the content of the pigment component including the extender pigment and the color pigment in the composition is A (parts by mass) and the content of the resin component is B (parts by mass). It is a value defined by the formula {A / (A + B)} × 100 (%).

  When such an aqueous receiving layer forming composition is used, the color developability of the coating pattern is increased when aqueous ink is used in ink jet coating.

  For example, spray coating, curtain coating, dipping, wire bar coating, applicator coating, spin coating, roll coating, electrodeposition coating, brush coating are applied to the surface of the substrate 1 provided with the sealer. The ink receiving layer can be formed by applying and curing by an appropriate method such as the above.

  After forming the ink receiving layer in this manner, ink jet coating is applied to the surface of the ink receiving layer.

  A water-based ink can be used as the ink used for ink-jet coating. As a water-based ink, a pigment ink in which a conventionally known pigment is dispersed with a dispersant can be used. However, it is difficult to increase the pigment concentration by inkjet coating, and the amount of the binder resin is small, so that the color of the printed matter is reduced. It tends to be dark, and the quality of the exterior decoration material is likely to be significantly reduced. From this point of view, an aqueous pigment-type ink comprising an aqueous dispersion of colored resin particles in which pigment particles are coated with a film-forming resin having an acid group neutralized at least partially with a base has excellent weather resistance. This is preferable because the color reproduction range is wide as well as the properties and high print quality can be obtained.

  The film-forming resin having an acid group is not particularly limited as long as it has a known acid group, but is preferably a resin having a carboxyl group having an acid value of 50 to 280. In the case of a self-water dispersible resin in which at least a part thereof is neutralized with a base, particularly excellent stability as a jet ink is exhibited.

  Examples of such a resin include an acrylic acid resin, a maleic acid resin, and a polyester resin, and a styrene- (meth) acrylic resin is particularly preferable. In addition, (meth) acryl includes both acryl and methacryl.

  The styrene- (meth) acrylic acid resin is a resin obtained by copolymerizing a (meth) acrylic acid monomer, for example, (meth) acrylic acid and / or (meth) acrylic acid ester, with a styrene monomer as an essential component. It is.

  Examples of the resin include substituted styrene such as styrene or α-methylstyrene, acrylic acid ester such as methyl acrylate, ethyl acrylate, butyl acrylate, 2-ethylhexyl acrylate, and methyl methacrylate. At least one monomer unit selected from esters, methacrylic acid ethyl ester, methacrylic acid butyl ester, methacrylic acid esters such as 2-ethylhexyl methacrylate, and at least one monomer unit selected from acrylic acid and methacrylic acid And a copolymer containing At least a part of these copolymers may be covalently crosslinked or ionically crosslinked with a polyvalent metal.

  When the resin is used as a self-water dispersible resin, at least a part of the carboxyl group may be neutralized with a base. Neutralization with a base, that is, an alkaline neutralizing agent, may be performed so that the obtained self-water dispersible resin does not dissolve in water. Examples of the base include alkali metal hydroxides such as sodium hydroxide, potassium hydroxide and lithium hydroxide, basic substances such as ammonia, triethylamine and morpholine, in particular triethanolamine, diethanolamine, N-methyldiethanolamine and the like. Alcohol amines, especially triethanolamine, are preferred as jet inks.

  When the pH of the ink in the presence of a base is in the range of 7 to 10, preferably 8 to 9, the resin containing the pigment is hardly dissolved in the ink and prevents nozzle clogging. In addition, a vivid color can be obtained and a clear pattern can be obtained.

  The pigment used in the above-mentioned water-based ink is not particularly limited. For example, inorganic pigments such as carbon black, titanium black, titanium white, zinc sulfide, bengara and yellow ocher, azo such as phthalocyanine pigment, monoazo, and disazo are used. There are organic pigments such as pigments, phthalocyanine pigments, and quinacridone pigments. The amount (content) of the pigment used is not particularly defined, but is preferably an amount that is 0.5 to 10% by mass in the finally obtained ink.

  The method for producing the colored resin particles in which the pigment is included by the resin is not particularly limited, but a more preferable specific example is obtained in the process shown in JP-A-10-88042. I can do it. It is preferable to use the following additives in combination with the thus obtained dispersion as necessary.

  Anti-drying agents are often added to water-based inks, and give the effect of preventing ink drying at the ink jet nozzles. Usually, water-soluble organic solvents having a boiling point higher than water are used. The Such an anti-drying agent is not particularly limited, and conventionally known polyhydric alcohols such as ethylene glycol, diethylene glycol, polyethylene glycol, glycerin, N-methyl-2-pyrrolidone, 2-pyrrolidone, etc. Pyrrolidones, amides, dimethyl sulfoxide, imidazolidinone and the like can be used. The usage-amount of a drying inhibitor changes with kinds, and is normally selected from the range of 1-150 mass parts with respect to 100 mass parts of water normally.

  In order to improve the penetration of the water-based ink into the ink receiving layer, it is preferable to use a necessary amount of a known and commonly used penetrant. As a penetrant, water-soluble organic solvents such as ethanol, isopropyl alcohol, etc., glycol ethers such as diethylene glycol-N-butyl ether, propylene glycol derivatives, pyrrolidone compounds, and the like, which exhibit the effect of imparting permeability to the ink receiving layer, and nonionic properties Or anionic and amphoteric surfactants may be added. In addition, additives such as water-soluble resins, preservatives, and chelating agents can be added as necessary.

  As a coating apparatus used for performing inkjet coating, the one shown in FIG. 1 can be exemplified. This coating apparatus controls the coating nozzle head 15 provided with the spray nozzle 10, the paint supply tank 9 that supplies paint to the spray nozzle 10 of the paint nozzle head 15, and the spray of paint from the spray nozzle 10 of the paint nozzle head 15. The ink jet type coating machine 12 provided with the coating control system 11 and the like, and a transport means 7 for transporting the substrate 1 are formed.

  The coating nozzle head 15 is provided at the lower end of the ink jet type coating machine 12 and is formed as a long line head in a direction perpendicular to the feed direction of the substrate 1.

  The coating nozzle head 15 is formed by four types of coating nozzle heads 15y, 15c, 15m, and 15k that eject paints of yellow, cyan, magenta, and black, so that full-color printing can be performed. is there. The number of coating nozzle heads 15 is not limited to this, and a number corresponding to the type of ink used is provided. Similarly, the paint supply tank 9 is composed of four types. The paint supply tank 9y that supplies yellow paint is applied to the coating nozzle head 15y, and the paint supply tank 9c that supplies cyan paint is applied to the coating nozzle head 15c. The paint supply tank 9m for supplying magenta paint is connected to the paint nozzle head 15m, and the paint supply tank 9k for supplying black paint is connected to the paint nozzle head 15k. And each coating nozzle head 15y, 15c, 15m, 15k is arranged along the conveyance direction of the base material 1. FIG.

  The painting control system 11 includes various CPUs, ROMs, RAMs, and the like, and includes a painting data creation unit, a painting control unit, an injection nozzle control unit, and the like. The painting data creation unit inputs and stores the color pattern data obtained by scanning the original image with a scanner or the like, and the painting control unit paints the color pattern data corresponding to the substrate 1 to be painted. A control signal is output from the data creation unit to the ejection nozzle control unit based on the color pattern data. The spray nozzle controller is connected to each spray nozzle 10 of the coating nozzle heads 15y, 15c, 15m, and 15k, and controls each spray nozzle 10 based on a control signal input from the spray nozzle controller. . The color pattern is prepared so that a predetermined pattern of paint is formed at a predetermined position on the base material 1 used for coating. Each ejection nozzle 10 is controlled to be ejected by, for example, a piezo control system or a control system for irradiating a photothermal exchange element with laser light. By controlling each ejection nozzle 10 with an ejection nozzle controller, yellow, It is possible to perform painting by full-color printing corresponding to the color pattern by individually controlling the spraying and stopping of the cyan, magenta, and black paints.

  The conveying means 7 can be formed by a belt conveyor 7 a in which an infinite belt 13 such as a timing belt is suspended between pulleys 14, and the conveying surface 16 constituted by the upper surface of the belt 13 is below the ink jet coating machine 12. Placed in.

  In performing inkjet coating, the base material 1 is first supplied to the conveying means 7. At this time, the plurality of base materials 1 can be sequentially conveyed at intervals.

  The base material 1 thus transported by the transport means 7 passes below the coating nozzle head 15. At this time, the ink is ejected from the coating nozzle head 15 toward the ink receiving layer on the base material 1 by an ink jet method, and the base material 1 to which the design pattern is given is obtained.

  On the surface of the ink receiving layer after inkjet coating, an aqueous clear paint is applied to form a clear layer for surface protection. As the water-based clear paint, for example, an appropriate paint such as acrylic, acrylic silicon, or acrylic urethane can be used.

  Aggregate is contained in this water-based clear paint. This reduces the fluidity of the clear paint after painting during the formation of the clear layer, suppresses the movement of water-based ink to the clear paint, and causes the design pattern formed by inkjet painting to bleed. It can be prevented and a clear design pattern can be expressed. Further, by preventing the water-based ink applied in the form of dots from bleeding as described above, it is possible to prevent the layer of the water-based ink from becoming thin due to such bleeding, and thus the building board Weather resistance can also be improved.

  Any suitable aggregate may be used, but acrylic resin beads, calcium carbonate fine particles, silica fine particles, and the like are preferably used. As aggregates, one kind can be used alone, or two or more kinds can be used in combination.

  As the acrylic resin beads, those having an average particle diameter in the range of 10 to 50 μm are preferably used. Here, the average particle diameter in this specification is measured by a laser diffraction particle size distribution meter. If the average particle diameter is less than 10 μm, the fluidity of the clear paint after application may not be sufficiently reduced. If the average particle diameter exceeds 50 μm, the gap between the particles of the acrylic resin beads becomes large, and the gap between the gaps is increased. There is a possibility that the paint may flow and the occurrence of bleeding cannot be sufficiently suppressed. The calcium carbonate fine particles preferably have an average particle size in the range of 20 to 50 μm, and the silica fine particles preferably have an average particle size in the range of 10 to 40 μm.

  The content of the aggregate is appropriately set according to the type of aggregate, particle size, etc. For example, when only acrylic resin beads are used as the aggregate, the content is 10 μm in average particle size. When it is less than 20 μm, it is in the range of 5 to 10% by mass with respect to the total amount of the clear paint, and when the average particle size is 20 to 50 μm, it is in the range of 7 to 15% by mass with respect to the total amount of the clear paint. Is preferred. If the content is too small, the movement of the water-based ink to the clear layer cannot be sufficiently suppressed, and if the content is excessive, the transparency of the clear layer is reduced and the design pattern is blurred. There is a fear.

  When only calcium carbonate fine particles are used as the aggregate, the content is preferably in the range of 5 to 20% by mass with respect to the total amount of the clear paint, and when only silica fine particles are used, the content is clear. It is preferably in the range of 3 to 15% by mass with respect to the total amount of paint. If this content is too small, the movement of the water-based ink to the clear layer cannot be sufficiently suppressed, and if the content is excessive, the clear layer may become turbid or the clear coating film has high hardness. Problems such as becoming too much may occur.

  Further, when aggregates such as acrylic resin beads, calcium carbonate fine particles, and silica fine particles are contained as described above, the gloss of the clear coating film can be reduced by these aggregates to express a deep design pattern. Furthermore, since acrylic resin-based beads have low water absorption and high acid resistance, it is possible to suppress the deterioration of the weather resistance of the clear coating film by adding aggregate.

  After applying such a water-based clear paint onto the surface of the ink-receiving layer after inkjet coating by spraying or the like, it is possible to form a clear layer by forming a film by baking and drying at 80 to 150 ° C. it can. The thickness of the clear layer is not particularly limited, but is preferably in the range of 1 to 10 μm.

Further, an inorganic paint layer can be further formed on the building board. The inorganic coating layer can be formed by applying an inorganic coating on the surface of the clear layer and thereby improving the weather resistance of the building board. An appropriate silicon alkoxide coating agent or the like can be used as the inorganic coating material. For example, a polyorganosiloxane or a condensation reaction catalyst such as an alkyl titanate is added to a silica-dispersed oligomer solution of organosilane, or silica is further added. An inorganic coating layer can be formed by using the added silicon alkoxide-based coating and applying it by electrostatic coating or the like, followed by baking at 60 to 120 ° C. to form a film. The thickness of the inorganic coating layer is not particularly limited, but is preferably in the range of 1 to 10 μm. It is also preferable to form a photocatalyst layer. The photocatalyst layer can be formed by coating an inorganic paint containing a photocatalyst on the surface of the inorganic paint layer, thereby improving the antifouling property of the building board. As the inorganic paint containing a photocatalyst, an appropriate one can be used. For example, a coating obtained by adding a photocatalyst such as titanium oxide to the silicon alkoxide paint as described above is applied by spray coating or the like. Then, a photocatalyst layer can be formed by forming a film by baking and drying at 60 to 120 ° C. The thickness of the photocatalyst layer is not particularly limited, but is preferably in the range of 0.2 to 1.0 μm.

(Examples 1 to 5, Comparative Examples 1 and 2)
As the substrate 1, a cement-based inorganic substrate was used.

In the production of the substrate 1, a sealer made of an acrylic emulsion paint is applied to the surface of a wet sheet before curing and curing formed with a cement-based molding material by a roll coater, and dried by heating at 250 ° C. for 20 minutes. A coating film of a sealer having an amount of 40 g / m ² was formed, and the wet sheet was cured and cured to obtain a substrate 1.

  A receiving layer forming composition (pigment content ratio PWC = 50% by mass) in which calcium carbonate fine particles are contained as a pigment in an acrylic emulsion paint is spray-coated on the surface of the base material 1 provided with a sealer coating, and 130 ° C. Was heated for 2 minutes to form an ink receiving layer having a thickness of 30 μm.

  The base material 1 on which the ink receiving layer was formed was subjected to ink jet coating on the surface of the ink receiving layer using a coating apparatus having the configuration shown in FIG.

  At this time, the water-based ink used for ink-jet coating was composed of 4% by mass of pigment, 35% by mass of ethylene glycol, 20% by mass of glycerin, 3% by mass of additive, and 38% by mass of water. The ink used was a yellow ocher, a cyan ink containing phthalocyanine, a magenta ink containing Bengala, and a black ink containing carbon black. Further, the amount of ink ejected from each ejection nozzle 10 for one dot was set to 27 pl.

  Next, a clear paint having the composition shown in Table 1 below was spray-coated on the surface of the ink receiving layer after inkjet coating, and heated at 130 ° C. for 2 minutes to form a clear layer having a dry film thickness of 20 μm.

  Next, the surface of the clear layer was spray-coated with an inorganic paint containing polyorganosiloxane, and heated at 130 ° C. for 2 minutes to form an inorganic paint layer having a dry film thickness of 5 μm.

Next, the surface of the inorganic coating layer is spray-coated with an inorganic coating containing polyorganosiloxane and titanium oxide at a ratio of 50% by mass, and heated at 130 ° C. for 2 minutes to dry a coating amount of 3 g / A photocatalytic layer of m ² was formed.

(Evaluation test)
The design pattern formed by inkjet coating of the building board thus obtained was visually observed to determine the degree of bleeding. At this time, A is the one where no bleeding is observed, B is the one where very little bleeding is observed, C is the one where bleeding is recognized, D is the one with large bleeding, and E is the one with very large bleeding. evaluated.
.

  The results are shown in Table 1.

  Further, the building board obtained in Example 5 and Comparative Example 1 was irradiated with continuous light on its surface using a sunshine weather meter (manufactured by Suga Test Instruments Co., Ltd., open frame carbon arc lamp) for 1 hour. An accelerated weathering test in which water was sprayed for 12 minutes every time was performed, and the change in color difference on the surface of each building board was measured using CR-200 manufactured by Minolta. At this time, the measurement of the color difference was performed on the area where each color of black, magenta, cyan, and yellow was applied to each building board. The result is shown in FIG.

  As shown in the results, in Example 5, the change in color difference was smaller than that in Comparative Example 1 for each of black, magenta, cyan, and yellow, and it was confirmed that the weather resistance was excellent.

It is the schematic which shows an example of an inkjet coating apparatus. It is a graph which shows the result of the accelerated weather resistance test about Example 5 and Comparative Example 1.

Explanation of symbols

  1 Base material

Claims (5)

  An architectural board that is coated with water-based ink and then coated with a clear layer on the base material, and the clear layer is formed with an aqueous clear paint containing aggregate Architectural board characterized by being made.   The building board according to claim 1, wherein the aggregate is acrylic resin beads having an average particle diameter of 10 to 50 µm.   The building board according to claim 1 or 2, wherein the aggregate is calcium carbonate fine particles.   The building board according to any one of claims 1 to 3, wherein the aggregate is silica fine particles.   The building board according to any one of claims 1 to 4, wherein an inorganic paint layer and a photocatalyst layer are sequentially laminated on the clear layer.

Images