JP6411871B2 - Decorative plate and manufacturing method thereof - Google Patents

Description

  The present invention relates to a ceramic decorative board that is nonflammable and can be used as an interior material even in an environment with extremely low humidity such as a low-humidity clean room, and a method for producing the same.

  As an interior material in low-humidity environments such as clean rooms, ceramic materials such as calcium silicate boards and fiber reinforced cement boards have been used as substrates, and a non-combustible material with a coating layer formed on the surface or a decorative film adhered. Ceramic-type decorative boards are used (Patent Document 1). Calcium silicate plates are highly heat-insulating because they are porous. On the other hand, even if they are porous, the dimensional change associated with moisture absorption and release is relatively small, that is, they are materials with relatively excellent dimensional stability. It is a material suitable for interior materials for clean rooms. However, recently, there is an increasing demand for clean rooms that are used to install, for example, lithium battery manufacturing facilities and the like and have extremely low humidity conditions. Calcium silicate plate is a material that is relatively excellent in dimensional stability even though it is porous, but when the humidity is extremely low, warpage may occur due to dimensional changes associated with moisture absorption and release, There is a need for non-combustible ceramic decorative panels suitable for interior materials in environments with higher dimensional stability and extremely low humidity.

JP 2008-155391 A

  That is, an object of the present invention is to provide a ceramic-based decorative board having good coating film performance and appearance while ensuring sufficient nonflammability and sufficient suitability for an extremely low humidity environment. .

  Therefore, as a result of various studies to solve the above problems, the present inventor used a papermaking gypsum plate as a substrate, and the film thickness of an undercoat layer and an overcoat layer formed with an organic coating film on the surface thereof, and a total film thereof It was found that a ceramic decorative panel having sufficient incombustibility and dimensional stability can be obtained by polishing the surface of the undercoat layer within a certain range of thickness, thereby completing the present invention.

That is, the present invention uses a papermaking gypsum board as a substrate, the surface of the substrate is subjected to polishing treatment and impregnation sealer treatment, and an organic coating layer having an undercoat layer and an overcoat layer on the surface of the substrate in this order. Have
(A) The undercoat layer is surface-polished and has a thickness of 5 to 120 μm,
(B) The thickness of the overcoat layer is 5 to 40 μm,
(C) Provided is a decorative board characterized in that the thickness of an organic coating layer composed of an undercoat layer and an overcoat layer is 140 μm or less.

Further, the present invention is a method for producing a decorative board in which a papermaking gypsum board is used as a substrate, the surface of the substrate is polished and then impregnated with a sealer, and then an undercoat layer and an overcoat layer are formed in this order.
(A) Applying an organic paint for forming an undercoat layer as an undercoat, curing, surface polishing, and forming an undercoat layer having a thickness of 5 to 120 μm;
(B) Applying an organic paint for forming an overcoat layer as the top coat and curing it to form an overcoat layer having a thickness of 5 to 40 μm;
(C) However, the present invention provides a method for producing a decorative board, wherein the thickness of the organic coating layer composed of the undercoat layer and the overcoat layer is 140 μm or less.

ADVANTAGE OF THE INVENTION According to this invention, the dimensional stability accompanying moisture absorption / release is very high, and the ceramics type decorative board which cleared the total calorific value by the corn calorimeter method exothermic test below legal 8MJ / m < ² > can be provided.

The decorative board of the present invention has a papermaking gypsum board as a substrate, the surface of the substrate is subjected to polishing treatment and impregnation sealer treatment, and an organic coating film having an undercoat layer and an overcoat layer on the surface of the substrate in this order. Has a layer,
(A) The undercoat layer is surface-polished and has a thickness of 5 to 120 μm,
(B) The thickness of the overcoat layer is 5 to 40 μm,
(C) A decorative board characterized in that the organic coating layer composed of an undercoat layer and an overcoat layer has a film thickness of 140 μm or less.

  In the present invention, the papermaking gypsum board used as a substrate is mainly composed of hydrated gypsum, which is a matrix forming raw material, an inorganic admixture (calcium carbonate powder, etc.), and a fiber raw material (wood pulp, etc.). Is added to mix to form a raw material slurry, and the raw material slurry is made into a predetermined thickness by a round net making machine to form an uncured green plate (green sheet), which is necessary for the raw plate It is a material obtained by performing press molding in response to curing and curing.

The paper-made gypsum board has an apparent density of approximately 1.5 to 1.7 g / cm ³ , and is a calcium silicate board (hereinafter referred to as a calcium silicate board) that has been used as a substrate for general clean room decorative boards. It is higher than the apparent density. On the other hand, the equilibrium moisture content of the papermaking gypsum board is about 0.3%, which is lower than the equilibrium moisture content of the calcium silicate board. In addition, the rate of change in length due to water absorption, which is a test for evaluating dimensional stability, is about 0.05 to 0.07% for a paper-made gypsum board, and is smaller than that of a calcium silicate board. Therefore, it is suitable for a ceramic decorative board for an environment that has higher dimensional stability and extremely low humidity.

  On the other hand, a papermaking gypsum board and a calcium silicate board are both materials manufactured by a papermaking method. In the papermaking method, pulp is used as a raw material as a papermaking fiber, and the blending ratio of the pulp is about the same in both the papermaking gypsum board and the calcium silicate board. Since the paper-made gypsum board has an apparent density higher than that of the calcium silicate board, the mass of the pulp contained per unit volume is larger than that of the calcium silicate board. Since the pulp is a combustible material, the calorific value per unit volume of the papermaking gypsum board is greater than that of the calcium silicate board. Moreover, when using it as an interior material of a clean room, there is no difference in thickness with a papermaking gypsum board and a calcium silicate board. Therefore, when a papermaking gypsum board is used as a substrate for a noncombustible ceramics decorative board, the heating value of the coating layer must be made lower than when a calcium silicate board is used in order to ensure nonflammability performance.

  For decorative boards with ceramic materials as substrates, paints suitable for clean rooms are currently resin-based organic paints, and there is not much difference in the amount of heat generated by the resin used, so the heat generated by the paint film In order to reduce the amount, it is necessary to reduce the thickness of the coating film. However, when the film thickness is reduced, there is a risk that the substrate concealing property (concealing so that the color of the substrate itself does not affect the appearance of the decorative board) and the coating film performance are deteriorated. Therefore, in the decorative board, it is desirable to form the organic coating film layer as thin as possible within a range in which the coating film performance can be ensured.

In addition, in this invention, the thickness of a board | substrate and a decorative board is the value measured according to JIS A 5430: 2008 10.2.2 paragraph b). The apparent density is in accordance with JIS A 5430: 2008 10.5, and the rate of change in length due to water absorption is a value measured in accordance with JIS A 5430: 2008 10.7. Therefore, drying was performed under the conditions of a standard drying temperature of 40 ° C. ± 2 ° C. shown in Table 2 of JIS A 1476: 2006 7.2. In the coating process, when the substrate is heat-dried on an industrial scale, it is common to perform a short-time treatment in an atmosphere of 90 to 110 ° C., which is regarded as a practical problem.
In addition, the equilibrium moisture content is JIS A 5404: 2007 Appendix A. According to the paragraph 2.6, the mass at a constant weight at 23 ° C. ± 2 ° C. and a relative humidity of 50% ± 5%, and the standard drying temperature 40 ° C. ± shown in Table 2 of JIS A 1476: 2006 7.2 It is the value calculated | required with the following formula | equation based on the mass when it dried on 2 degreeC conditions.

(Equation 1)
Equilibrium moisture content = (mass at constant weight−mass after drying) / mass after drying × 100 (%)

  The total calorific value of the substrate and the decorative board was measured by a corn calorimeter method exothermic test (ISO 5660-1: 2002 compliant).

  In order to form an organic coating layer as thin as possible within the range that can ensure the coating performance, at least the surface of the substrate on which the coating layer is formed (hereinafter referred to as the substrate surface) is polished and smoothed. Increase the degree. If the surface of the substrate opposite to the side on which the coating film layer is formed (hereinafter referred to as the back surface of the substrate) is also polished, the smoothness can be further enhanced. As a polishing method, a belt sander, a platen polishing machine or the like is preferably used. These polishing machines continuously polish the substrate surface while holding the belt-like abrasive paper with a cylindrical roller or platen pad, so that only the convex part of the substrate is removed from the surroundings using the smooth surface of the roller or pad. Can also be polished. Also, by changing the position of the roll, the pressure of the pad, etc., the pressure applied to the substrate and the polishing load can be adjusted arbitrarily, so it is easy to obtain the optimum polishing conditions according to the unevenness of the substrate, and the entire surface can be uniformly polished it can. Also, by making the size of the polishing machine and polishing paper matched to the substrate, the substrate surface can be polished continuously, and because it uses a continuous belt-like polishing paper, it is excellent in discharging dust, Compared to other polishing methods, it has a feature of excellent processing speed. Paper-made gypsum board is a material that is softer than calcium silicate board and is easy to obtain surface smoothness by polishing. Compared to the case where calcium silicate board is used as a substrate, the appearance required as a coating film is relatively thin. And performance. In addition, it is preferable that a papermaking gypsum board adjusts a moisture content to 0.1 to 2% prior to a grinding | polishing process.

An impregnation sealer treatment is performed on the surface of the substrate. By performing the impregnation sealer treatment, the surface layer of the substrate is strengthened, and the adhesion with the undercoat layer as an upper layer is also improved.
The impregnated sealer layer can be formed using a known sealer. For example, the impregnated sealer layer is formed by applying a curable resin such as a moisture curable urethane resin or an epoxy resin to the surface of the substrate and curing it. The impregnation sealer has good impregnation into the substrate, has a high non-volatile content, and reacts with moisture in the substrate or moisture in the atmosphere to form a three-dimensional cross-link. A moisture-curing urethane-based material mainly comprising a prepolymer having a free isocyanate group as a reaction product and a solvent such as butyl acetate is preferred. When yellowing as a decorative board is a problem, aliphatic isocyanates such as HDI (hexamethylene diisocyanate), alicyclic isocyanates such as IPDI (isophorone diisocyanate), MDI (methylene bis (4,1-phenylene) It is preferred to use aromatic isocyanates such as = diisocyanate). In addition, from the viewpoint of volatile organic compound (VOC) countermeasures, a solventless sealer that does not contain a solvent, an inorganic sealer such as a silicate sealer such as lithium silicate or sodium silicate, tetra Silane compound sealers mainly composed of ethoxysilane, tetramethoxysilane or the like can also be used.
The impregnation sealer treatment can be performed by adjusting the surface temperature of the papermaking gypsum plate to a range of 5 to 50 ° C., applying the impregnation sealer by a method such as a known roll coater or spray, and then curing. The viscosity of the impregnating sealer can be appropriately determined in consideration of the type of impregnating sealer to be used and the coating method, and the curing can be performed by, for example, drying by heating.

  Further, in the present invention, it is preferable to reinforce the back surface of the substrate by impregnating the sealer. This is because a bonding method is often used as a method for applying the decorative plate, and if the back surface of the substrate is reinforced, the workability is improved. When the impregnation sealer treatment is performed also on the back surface of the substrate, the back surface impregnation sealer treatment is generally performed before the undercoat layer described later is formed, but may be performed after the undercoat layer is formed.

In this invention, it is preferable to set so that the amount of organic solids in the component of an impregnation sealer may be 3-100g per unit area (m < ² >) of a board | substrate. If the organic solid content is too small, the surface layer of the substrate may not be strengthened so much. In addition, the adhesion with the undercoat layer that is the upper layer may be lowered. If the amount of organic solids is too large, excess organic solids remain on the surface layer of the substrate, and this organic solid layer may cause defects such as cohesive peeling, foaming in the subsequent process, and side. In addition, aside is a minute hole made by the gas in the foam breaking the coating in foaming. It is caused by a local thick film at the time of painting, and is mainly caused by a rapid temperature rise at the time of drying. . More preferably, the organic solid content in the impregnated sealer component is set to 3 to 80 g per unit area (m ² ) of the substrate. Further, when the impregnation sealer treatment is performed on the back surface of the substrate, the organic solid content in the component of the impregnation sealer is more preferably set to be 10 to 30 g per unit area (m ² ) of the substrate.

  In the present invention, the amount of organic solids can be calculated from the composition of the coating stock solution, the amount of diluent used, and the actual coating amount.

  The decorative board of the present invention has an undercoat layer on an impregnated sealer-treated substrate, the surface of the undercoat layer is polished, and it is important that the film thickness is 5 to 120 μm. By forming the undercoat layer, large and small uneven portions and void portions existing on the surface of the substrate are filled with the paint, and the uneven feeling and the gloss / color variation feeling due to the paint suction spots are suppressed. In addition, the possibility of defects such as pinholes on the decorative board is reduced. Further, after the undercoat layer is formed, the surface is polished. By performing the polishing treatment, the base becomes smooth, and the design properties of the coating film of the overcoat layer formed thereon are not impaired, and good coating film performance can be ensured.

  The film thickness of the undercoat layer is from 5 to 120 μm. The surface smoothness of the decorative board, the adhesion to the coating film of the topcoat layer, the substrate concealing property, the waterproof property, the precipitation prevention property of the substrate components, the coating film pinhole Are important in terms of prevention of coating, film curability, surface foreign matter burying property, and ease of film thickness control. If it is less than 5 micrometers, there exists a possibility that adhesiveness with the upper layer and the lower layer coating film may fall. On the other hand, if it exceeds 120 μm, the total calorific value increases, which may lead to deterioration of nonflammability, and when used in an extremely low humidity environment, the decorative board warps due to drying shrinkage of the coating film. It becomes easy. A preferable coating film is 5-70 micrometers, More preferably, it is 10-50 micrometers.

  The paint used to form the undercoat layer is a radical oligomer based paint in terms of substrate concealment, surface smoothness, chemical resistance, paint film adhesion, polishing processability, paint film hardness, ease of painting, and crack prevention. And monomer radical paints such as epoxy acrylates, urethane acrylates, ester acrylates, acrylic acrylates, silicon acrylates, unsaturated polyester paints, specifically epoxy acrylates, urethane acrylates, diallyl phthalate esters, etc. Allylic unsaturated polyesters, maleic unsaturated polyesters by polycondensation of unsaturated dibasic acids such as maleic anhydride and fumaric acid with glycols, polyester monoacrylates having a carboxyl group or a hydroxyl group as functional groups, acrylic acid And dibasic acid and divalent al Polyester diacrylate obtained from a polyol, polyester acrylate such as polyester polyacrylate obtained from trihydric or higher polyhydric alcohol, dibasic acid and acrylic acid, oligomers such as epoxy acrylate oligomer and epoxy oligomer, acrylic polyether, poly Examples include ether acrylate. In addition, the coating material for forming the undercoat layer should be an ultraviolet curable coating material. It is easy to apply, has a fast coating curing speed, is easy to grind and has durability, and is compatible with the substrate and top coating. It is preferable because of excellent adhesion. After applying the paint, the paint is cured by irradiating with ultraviolet rays to form an undercoat layer and then polished. Further, the coating material for forming the undercoat layer is preferably one to which an inorganic pigment such as calcium carbonate is added for the purpose of securing the substrate concealing property and reducing the heat generation amount by reducing the content of combustible materials. Examples of the method of applying the undercoat paint include a method using a roll coater, a flow coater, etc. Among them, a roll coater is suitable in consideration of the effect of filling large and small uneven portions and voids on the substrate surface with the paint. Yes.

In the present invention, the organic solid content in the component of the undercoat layer is set to 3 to 60 g, preferably 3 to 35 g, more preferably 5 to 25 g per unit area (m ² ) of the substrate.

  The undercoating for forming the undercoating layer can be performed once to form an undercoating layer having a predetermined thickness, or can be performed twice or more to form an undercoating layer having a predetermined thickness. For example, in the case of forming the undercoat layer of a predetermined film thickness by performing the undercoat coating twice, when the undercoat paint is cured by irradiating ultraviolet rays after the first undercoat coating, It is adjusted so as not to be completely cured, and after the second undercoat is applied thereon, ultraviolet rays are irradiated again to completely cure the entire undercoat and form an undercoat layer. Also, when the undercoat is applied three or more times, as in the case of twice, the entire undercoat is completely cured by ultraviolet irradiation after the last undercoat is applied to form an undercoat layer. In the decorative board of the present invention, a paper-made gypsum board having a higher calorific value than that of the calcium silicate board is used as a substrate. Therefore, in order to ensure the required coating film performance and nonflammability, it is important to control the coating thickness. It is. From this viewpoint, in order to efficiently obtain the effect of filling large and small uneven portions and voids existing on the substrate surface with the paint and the effect of further improving the surface smoothness, the coating of the undercoat layer is performed twice. A film should be formed.

  Examples of means for polishing the surface after forming the undercoat layer include buffing, platen polishing, polisher polishing, blast polishing, etching polishing, grindstone polishing, felt polishing, brush polishing, laser polishing, cutting with an end mill or a bite, and the like. However, platen polishing is preferable from the viewpoint of smoothing the surface of the undercoat layer and polishing properties. In the platen polishing, an endless belt-like polishing paper that is driven to rotate is pressed against the object to be polished with a soft pad, and the object to be polished is advanced and polished. When the undercoating is performed a plurality of times, only the surface of the formed undercoating layer may be polished, or surface polishing can be performed every time the undercoating is applied and cured (semi-cured). By polishing the undercoat layer, the final undercoat layer thickness is adjusted to 5 to 120 μm, preferably 5 to 70 μm, more preferably 10 to 50 μm.

  The decorative board of the present invention has an overcoat layer having a thickness of 5 to 40 μm as an upper layer of the undercoat layer. By forming the overcoat layer, the decorative panel of the present invention has a good appearance, and coating film performance suitable for applications such as clean rooms (anti-dust generation, vibration durability due to air-conditioning wind pressure, repairability, cleaning work resistance, drying resistance, etc. (Cracking property, smoothness, base concealing property, etc.). The film thickness of the overcoat layer needs to be 5 to 40 μm, more preferably 10 to 40 μm, and still more preferably 25 to 40 μm, in order to impart the above-described characteristics. If the film thickness of the overcoat layer exceeds 40 μm, the nonflammable performance of the decorative board may be reduced, and when used in an extremely low humidity environment, the decorative board warps due to drying shrinkage of the coating film. It becomes easy to do. Moreover, it is not preferable that the film thickness of the overcoat layer is less than 5 μm because the coating film performance is deteriorated.

  The paint used for forming the topcoat layer is from the viewpoint of coating workability, coating film drying property after coating, safety, durability after coating, coating surface hardness, coating chemical resistance and stain resistance. An acrylic urethane resin paint is preferable, and a two-component curable acrylic urethane resin paint is more preferable. Also, acrylic resin paints, epoxy resin paints, polyurethane resin paints, vinyl chloride resin paints, vinylidene chloride resin paints, acrylic silicone resin paints, fluororesin paints, etc., in a single layer, with the same paint film laminated, or A top coat layer is formed by laminating coatings of different paints.

  Examples of the top coating method for forming the top coating layer include a method using a roll coater, a flow coater, a spray coater and the like. The top coat can form an overcoat layer having a predetermined film thickness once, or can be performed twice or more to form an overcoat layer having a predetermined film thickness. In the decorative board of the present invention, a paper-made gypsum board having a higher calorific value than that of the calcium silicate board is used as a substrate. Therefore, in order to ensure the required coating film performance and nonflammability, it is important to control the coating thickness. It is. From this point of view, it is preferable to form a coating film of the top coating layer by performing the top coating twice, and it is particularly preferable to perform the top coating with a roll coater at the first time and the top coating with a flow coater at the second time. preferable.

In the present invention, the amount of organic solids in the components of the topcoat layer is preferably set to be 5 to 35 g per unit area (m ² ) of the substrate, and more preferably 10 to 33 g. When the top coat is applied with the roll coater for the first time and the top coat is applied for the second time with the flow coater, the organic solid content per unit area (m ² ) of the substrate is 1 to 15 g with the roll coater for the first time. Preferably it is 2-13g, and it is good to apply | coat so that it may become 4-20g with a flow coater in the 2nd time, More preferably, it is 8-20g.

  After the top coat is applied, the substrate is held horizontally for a while to level the top coat and smooth the coated surface, followed by heat drying to cure the top coat and form the top coat layer. Heat drying is preferably performed in an atmosphere of 90 to 110 ° C. for about 30 minutes.

In the decorative board of the present invention, in order to ensure nonflammability, the thickness of the organic coating layer composed of the undercoat layer and the topcoat layer is 140 μm or less, preferably 100 μm or less. As described above, the paper-made gypsum board has a large calorific value per unit volume compared to the calcium silicate board, so that the thickness of the organic coating layer is the above-mentioned condition, the coating film performance necessary as a decorative board And incombustibility are important. Further, when the organic coating layer is too thick when used in an extremely low humidity environment, the decorative board is likely to warp due to drying shrinkage of the coating. Further, the total thickness of the organic coating layer of the undercoat layer and the topcoat layer is preferably 10 μm or more, and more preferably 20 μm or more. In this case, the total amount of organic solids in the organic coating layer of the undercoat layer and the overcoat layer is preferably 70 g or less, more preferably 58 g or less, per unit area (m ² ) of the substrate. The total amount is preferably 8 g or more per unit area (m ² ) of the substrate, more preferably 15 g or more.

The decorative board of the present invention is a method for producing a decorative board in which a paper-made gypsum board is used as a substrate, the surface of the substrate is polished and then impregnated with a sealer, and then an undercoat layer and an overcoat layer are formed in this order. a) Applying an organic paint for forming an undercoat layer as an undercoat, curing, polishing, and forming an undercoat layer having a thickness of 5 to 120 μm;
(B) Applying an organic paint for forming an overcoat layer as the top coat and curing it to form an overcoat layer having a thickness of 5 to 40 μm;
(C) However, it can be produced by setting the film thickness of the organic coating layer composed of the undercoat layer and the overcoat layer to 140 μm or less. The method for forming each coating layer is as described above.

The decorative board of the present invention needs to have a total calorific value of 8 MJ / m ² or less by a corn calorimeter exothermic test. Satisfying this requirement satisfies exothermic first grade (heating time 20 minutes) defined in JIS A 5430: 2008, and exhibits high nonflammability. A more preferable total calorific value is 7.2 MJ / m ² or less.

  When the manufactured decorative board is stacked and loaded for storage or transportation, it is preferable to cool the board to 40 ° C. or lower in order to avoid so-called blocking.

  The method for providing a coating layer on one side of the substrate has been described above. However, in the present invention, a coating layer can also be provided on the back side of the substrate. Providing a coating layer on the back surface of the substrate can further enhance the dimensional stability of the decorative board. However, when a coating layer is provided also on the back surface of the substrate, the total film thickness of the organic coating layer on the front surface and the back surface of the substrate needs to be 140 μm or less in order to ensure nonflammability performance.

  EXAMPLES Hereinafter, although an Example and a comparative example further demonstrate this invention, this invention is not restrict | limited to the following example.

(1) Paper plasterboard (substrate)
As the substrate, an FG board (manufactured by A & A Materials Co., Ltd.) having a thickness of 5 mm was used. The FG board used in the examples and comparative examples is a blend of 5.5% by mass of pulp as an organic fiber raw material, the apparent density is 1.6 g / cm ³ , and the length change rate due to water absorption is 0.06. %, The equilibrium water content was 0.3%.

(2) Paint Each painting was performed using the following paint.
Impregnation sealer 1: DIC Corporation UC sealer W004K (isocyanate type)
Impregnated sealer 2: Dai Nippon Paint Co., Ltd. V Seran # 100 NS sealer (isocyanate type)
Undercoat paint 1: DIC Corporation SKS-WP (unsaturated polyester)
Undercoat paint 2: Dainippon Paint Co., Ltd. Lucen # 600NR-1 (epoxy acrylate)
Undercoat paint 3: Dainippon Paint Co., Ltd. Lucen # 600NR-2 (epoxy acrylate)
Top coating: Dainippon Paint ASA # 100PRTR (acrylic urethane)

Example 1
Using a roll coater, 70 g / m ² of impregnation sealer 1 having an organic solid content concentration of 40% is applied to the surface of the substrate adjusted to a moisture content of 0.5%, while the immersion sealer is applied to the back surface of the substrate. 1 was applied at 20 g / m ² to form an impregnated sealer layer having an organic solid content of 36 g / m ^{2 over the} entire front and back surfaces of the substrate.
Next, after applying 50 g / m ² of the undercoat paint 1 to the substrate surface side using a roll coater, the undercoat paint is partially cured by ultraviolet irradiation to form a coating film, and then again using the roll coater, After applying 50 g / m ^{2 of the} undercoat paint 1 on the film, the undercoat paint was completely cured by ultraviolet irradiation to form a coating film. Next, the surface of the coating film was smoothly polished by a platen polishing machine to form an undercoat layer having a thickness of 40 μm and an organic solid content of 20 g / m ² .
Furthermore, after applying a top coat of 10 g / m ² using a roll coater from above the undercoat layer, applying the same top coat of 95 g / m ² using a flow coater, and using a hot air dryer at 100 ° C. Then, the top coat film was cured by heating for 30 minutes to form a top coat layer having a film thickness of 30 μm and an organic solid content of 26 g / m ² to obtain a decorative board. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 70 μm.

Example 2
An impregnation sealer treatment was performed in the same manner as in Example 1 to form an undercoat layer having an undercoat layer thickness of 8 μm and an organic solid content of the undercoat layer of 4 g / m ² using the same paint and coating method as in Example 1. did. Next, in the same manner as in Example 1, a top coat was applied at 10 g / m ² using a roll coater, and then the same top coat was applied at 95 g / m ² using a flow coater. An overcoat layer having an organic solid content of 26 g / m ² was formed to prepare a decorative board. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 38 μm.

Example 3
An impregnation sealer treatment was performed in the same manner as in Example 1 to form an undercoat layer having an undercoat layer thickness of 120 μm and an organic solid content of the undercoat layer of 60 g / m ² using the same paint and coating method as in Example 1. did. Next, in the same manner as in Example 1, 5 g / m ^{2 of the} top coating was applied using a roll coater, and then 58 g / m ^{2 of the} same top coating was applied using a flow coater. An overcoat layer having an organic solid content of 15.6 g / m ² was formed to prepare a decorative board. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 138 μm.

Example 4
An impregnation sealer treatment was performed in the same manner as in Example 1, and an undercoat layer having an undercoat layer thickness of 40 μm and an undercoat layer organic solid content of 20 g / m ² was formed using the same paint and coating method as in Example 1. did. Next, 21 g / m ² of the top coating material was applied by a single application using a roll coater to form a top coating layer having a film thickness of 6 μm and an organic solid content of the top coating layer of 5.2 g / m ^2. Was made. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 46 μm.

Example 5
An impregnation sealer treatment was performed in the same manner as in Example 1, and an undercoat layer having an undercoat layer thickness of 40 μm and an undercoat layer organic solid content of 20 g / m ² was formed using the same paint and coating method as in Example 1. did. Next, in the same manner as in Example 1, the top coat was applied at 18 g / m ² using a roll coater, and then the same top coat was applied at 115 g / m ² using a flow coater. An overcoat layer having an organic solid content of 32.9 g / m ² was formed to prepare a decorative board. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 78 μm.

Comparative Example 1
An impregnation sealer treatment was performed in the same manner as in Example 1 to form an undercoat layer having an undercoat layer thickness of 4 μm and an organic solid content of the undercoat layer of ² g / m ² using the same paint and coating method as in Example 1. did. Next, in the same manner as in Example 1, a top coat was applied at 10 g / m ² using a roll coater, and then the same top coat was applied at 95 g / m ² using a flow coater. An overcoat layer having an organic solid content of 26 g / m ² was formed to prepare a decorative board. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 34 μm.

Comparative Example 2
An impregnation sealer treatment was performed in the same manner as in Example 1 to form an undercoat layer having an undercoat layer thickness of 140 μm and an undercoat layer organic solid content of 70 g / m ² using the same paint and coating method as in Example 1. did. Next, in the same manner as in Example 1, a top coat was applied at 30 g / m ² using a roll coater to form a top coat layer having a film thickness of 9 μm and an organic solid content of the top coat layer of 7.4 g / m ² . A decorative board was produced. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 149 μm.

Comparative Example 3
An impregnation sealer treatment was performed in the same manner as in Example 1, and an undercoat layer having an undercoat layer thickness of 40 μm and an undercoat layer organic solid content of 20 g / m ² was formed using the same paint and coating method as in Example 1. did. Then, a top coat paint in a single coat using a roll coater 7 g / m ² was applied, the film thickness to form a top coat layer organic solid content of the overcoat layer is 1.7 g / m ² at 2 [mu] m, the veneer Produced. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 42 μm.

Comparative Example 4
An impregnation sealer treatment was performed in the same manner as in Example 1, and an undercoat layer having an undercoat layer thickness of 40 μm and an undercoat layer organic solid content of 20 g / m ² was formed using the same paint and coating method as in Example 1. did. Next, in the same manner as in Example 1, after applying the top coat 20 g / m ² using a roll coater, the same top coat was applied 160 g / m ² using a flow coater. An overcoat layer having an organic solid content of 44.5 g / m ² was formed to prepare a decorative board. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 91 μm.

Comparative Example 5
Undercoating sealer treatment as in Example 1, and using the same paint and coating method as in Example 1, the undercoating layer has a thickness of 115 μm and the organic solid content of the undercoating layer is 57.5 g / m ² Formed. Next, in the same manner as in Example 1, a top coat was applied at 12 g / m ² using a roll coater, and then the same top coat was applied at 125 g / m ² using a flow coater. An overcoat layer having an organic solid content of 33.8 g / m ² was formed to prepare a decorative board. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 154 μm.

Comparative Example 6
A decorative board similar to that of Example 1 was produced except that the surface of the undercoat coating was not polished. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 130 μm.

(3) Evaluation Performance evaluation of the organic coating layer: The chemical resistance of the decorative board was evaluated according to JIS K 5600-6-1: 1999, paragraph 9. For the test solution dropped on the coating film, the acid, alkali and organic solvents listed in Table 1 were used for 24 hours, and no change was observed in the appearance. A slight discoloration was observed in the appearance. The case where there was no problem was indicated by ◯, the case where the use conditions were restricted because the appearance was observed to be changed, and the case where the appearance was clearly changed or changed.
Total calorific value: Measured by a cone calorimeter method exothermic test (ISO 5660-1: 2002 compliant).
Appearance: Excellent by visual observation, ◎, unsatisfactory by x, intermediate (substantially good) by ◯.

  The obtained evaluation results are shown in Table 1.

Example 6
Using a roll coater, 25 g / m ² of impregnated sealer 2 having an organic solid content concentration of 100% is applied to the surface of the substrate adjusted to a moisture content of 0.5%. 2 was applied at 10 g / m ² to form an impregnated sealer layer having an organic solid content of 35 g / m ^{2 over the} entire front and back surfaces of the substrate.
Next, after applying 50 g / m ² of the undercoating material 2 to the substrate surface side using a roll coater, the undercoating material is partially cured by ultraviolet irradiation to form a coating film, and then again using the roll coater, After 50 g / m ² of the undercoat paint 3 was applied on the film, the undercoat paint was completely cured by ultraviolet irradiation to form a coating film. Next, the surface of the coating film was smoothly polished by a platen polishing machine to form an undercoat layer having a thickness of 40 μm and an organic solid content of 20 g / m ² .
Furthermore, after applying a top coat of 10 g / m ² using a roll coater from above the undercoat layer, applying the same top coat of 95 g / m ² using a flow coater, and using a hot air dryer at 100 ° C. Then, the top coat film was cured by heating for 30 minutes to form a top coat layer having a film thickness of 30 μm and an organic solid content of 26 g / m ² to obtain a decorative board. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 70 μm.

Example 7
An impregnation sealer treatment was performed in the same manner as in Example 6, and an undercoat layer having an undercoat layer thickness of 8 μm and an undercoat layer organic solid content of 4 g / m ² was formed using the same paint and coating method as in Example 6. did. Next, in the same manner as in Example 6, the top coat was applied at 10 g / m ² using a roll coater, and then the same top coat was applied at 95 g / m ² using a flow coater. An overcoat layer having an organic solid content of 26 g / m ² was formed to prepare a decorative board. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 38 μm.

Example 8
Undercoating sealer treatment in the same manner as in Example 6, using the same paint and coating method as in Example 6, the undercoating layer having an undercoating layer thickness of 121 μm and the organic solid content of the undercoating layer of 60.5 g / m ² Formed. Next, in the same manner as in Example 6, after applying 5 g / m ^{2 of the} top coat using a roll coater, 58 g / m ^{2 of the} same top coat was applied using a flow coater. An overcoat layer having an organic solid content of 15.6 g / m ² was formed to prepare a decorative board. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 139 μm.

Example 9
An impregnation sealer treatment was performed in the same manner as in Example 6 to form an undercoat layer having a thickness of 40 μm and an organic solid content of the undercoat layer of 20 g / m ² using the same paint and coating method as in Example 6. did. Next, 21 g / m ² of the top coating material was applied by a single application using a roll coater to form a top coating layer having a film thickness of 6 μm and an organic solid content of the top coating layer of 5.2 g / m ^2. Was made. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 46 μm.

Example 10
An impregnation sealer treatment was performed in the same manner as in Example 6 to form an undercoat layer having a thickness of 40 μm and an organic solid content of the undercoat layer of 20 g / m ² using the same paint and coating method as in Example 6. did. Next, in the same manner as in Example 6, the top coat was applied at 18 g / m ² using a roll coater, and then the same top coat was applied at 115 g / m ² using a flow coater. An overcoat layer having an organic solid content of 32.9 g / m ² was formed to prepare a decorative board. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 78 μm.

Comparative Example 7
An impregnation sealer treatment was performed in the same manner as in Example 6 to form an undercoat layer having an undercoat layer thickness of 4 μm and an organic solid content of the undercoat layer of ² g / m ² using the same paint and coating method as in Example 6. did. Next, in the same manner as in Example 6, the top coat was applied at 10 g / m ² using a roll coater, and then the same top coat was applied at 95 g / m ² using a flow coater. An overcoat layer having an organic solid content of 26 g / m ² was formed to prepare a decorative board. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 34 μm.

Comparative Example 8
An impregnation sealer treatment was performed in the same manner as in Example 6 to form an undercoat layer having a thickness of 138 μm and an organic solid content of the undercoat layer of 69 g / m ² using the same paint and coating method as in Example 6. did. Next, in the same manner as in Example 6, a top coat was applied at 30 g / m ² using a roll coater to form a top coat layer having a film thickness of 9 μm and an organic solid content of the top coat layer of 7.4 g / m ² . A decorative board was produced. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 147 μm.

Comparative Example 9
An impregnation sealer treatment was performed in the same manner as in Example 6 to form an undercoat layer having a thickness of 40 μm and an organic solid content of the undercoat layer of 20 g / m ² using the same paint and coating method as in Example 6. did. Then, a top coat paint in a single coat using a roll coater 7 g / m ² was applied, the film thickness to form a top coat layer organic solid content of the overcoat layer is 1.7 g / m ² at 2 [mu] m, the veneer Produced. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 42 μm.

Comparative Example 10
An impregnation sealer treatment was performed in the same manner as in Example 6 to form an undercoat layer having a thickness of 40 μm and an organic solid content of the undercoat layer of 20 g / m ² using the same paint and coating method as in Example 6. did. Next, in the same manner as in Example 6, after applying the top coat 20 g / m ² using a roll coater, the same top coat 160 g / m ^{2 was} applied using a flow coater. An overcoat layer having an organic solid content of 44.5 g / m ² was formed to prepare a decorative board. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 91 μm.

Comparative Example 11
An impregnation sealer treatment was performed in the same manner as in Example 6 to form an undercoat layer having a thickness of 118 μm and an organic solid content of the undercoat layer of 59 g / m ² using the same paint and coating method as in Example 6. did. Next, as in Example 6, the top coat was applied at 12 g / m ² using a roll coater, and then the same top coat was applied at 125 g / m ² using a flow coater. An overcoat layer having an organic solid content of 33.9 g / m ² was formed to prepare a decorative board. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 157 μm.

Comparative Example 12
A decorative board similar to that of Example 6 was produced except that the surface of the undercoat film was not polished. The film thickness of the organic coating layer combining the undercoat layer and the topcoat layer of this decorative plate was 132 μm.

(4) Evaluation It evaluated similarly to the said Example 1.
The obtained evaluation results are shown in Table 2.

As is clear from Table 1 and Table 2, the appearance and the coating film performance are good by forming an undercoat layer and an overcoat layer on the surface of the papermaking gypsum board, making each layer a predetermined thickness, and polishing the undercoat layer. A decorative board having excellent nonflammability with a total calorific value of 8 MJ / m ² or less is obtained. Moreover, this decorative board has suitability as an interior material of a low humidity clean room.
On the other hand, Comparative Example 1 and Comparative Example 7 where the undercoat layer is as thin as 4 μm are poor in appearance because the uneven traces of the substrate remain on the surface and the smoothness is insufficient, and the total thickness of the organic coating layer exceeds 140 μm In Example 2, Comparative Example 5, Comparative Example 8 and Comparative Example 11, the calorific value is higher than 8 MJ / m ² , and the overcoat layer is as thin as 2 μm. Comparative Example 6 and Comparative Example 12 in which the surface of the undercoat film was not polished were observed on the surface. The traces of fluff on the substrate remained and the surface smoothness was insufficient.

Next, decorative plates (1820 mm long × 910 mm wide) of Example 1 and Comparative Example 4 were prepared, and the decorative plate was cut into a length of 500 mm × width of 400 mm to test 12 test pieces of Example 1, a test of a comparative example. Twelve pieces were prepared, and an aptitude test was conducted for a case where the humidity was extremely low.
(Implementation content)
(1) Drying room: Dry air is sent into the space surrounded by a combination of multiple transparent resin plates using an ultra-low dew point air dryer, and the inside is always kept at positive pressure to prevent inflow of outside air. A drying chamber was provided. The inside of the drying chamber was adjusted to an extremely low humidity environment where the temperature was 23 ° C. ± 5 ° C. and the relative humidity was 1% or less.
(2) Base: A frame body having an outer dimension of 500 mm x 400 mm is assembled using a square pipe steel material of 50 mm x 50 mm, and a gypsum board (JIS A 6901: length 500 mm x width 400 mm, thickness 12.5 mm). 2005) was fixed with screws and used as the base of the test specimen.
(3) Specimen: The specimen was fixed to the base to obtain a specimen. The fixing method was performed using a double-sided tape and an elastic adhesive in the same manner as a general clean room interior construction method.
(4) Evaluation method: After the test specimen was left in the drying chamber for one month, the presence or absence of warpage and cracking due to drying shrinkage or the like was visually determined.
As a result of performing the above test on each of the 12 test pieces, a slight warpage was observed in 4 of 12 specimens in Comparative Example 4, whereas in all 12 specimens in Example 1 warped. No cracks were observed. Therefore, it was confirmed that the decorative board according to the present invention has sufficient suitability as a ceramic decorative board used in an extremely low humidity environment.

Claims (8)

A papermaking gypsum board adjusted to a moisture content of 0.1 to 2% is used as a substrate, and the surface of the substrate is subjected to a polishing treatment followed by an impregnation sealer treatment. An undercoat layer and an overcoat layer are formed on the surface of the substrate. Has an organic coating layer in order,
(A) The undercoat layer is surface-polished and has a thickness of 5 to 120 μm,
(B) The thickness of the overcoat layer is 5 to 40 μm,
(C) A decorative board, wherein the organic coating layer comprising an undercoat layer and an overcoat layer has a thickness of 140 μm or less. The decorative board according to claim 1, wherein the total calorific value by a corn calorimeter method exothermic test is 8 MJ / m ² or less.   The decorative board according to claim 1 or 2, wherein the back surface of the substrate is impregnated with a sealer.   The undercoat layer is a layer made of UV curable paint, and the overcoat layer is acrylic urethane resin paint, acrylic resin paint, epoxy resin paint, polyurethane resin paint, vinyl chloride resin paint, vinylidene chloride resin paint, acrylic silicone resin paint, and fluororesin paint. The decorative board according to any one of claims 1 to 3, wherein the decorative board is one or more layers selected from the group consisting of: A method for producing a decorative board in which a papermaking gypsum board adjusted to a moisture content of 0.1 to 2% is used as a substrate, the surface of the substrate is polished and then impregnated with a sealer, and then an undercoat layer and an overcoat layer are formed in this order Because
(A) Applying an organic paint for forming an undercoat layer as an undercoat, curing, surface polishing, and forming an undercoat layer having a thickness of 5 to 120 μm;
(B) Applying an organic paint for forming an overcoat layer as the top coat and curing it to form an overcoat layer having a thickness of 5 to 40 μm;
(C) However, the manufacturing method of the decorative board characterized by making the film thickness of the organic coating film layer which consists of the said undercoat layer and the said overcoat layer into 140 micrometers or less. (D) The method for producing a decorative board according to claim 5, wherein the total calorific value by a corn calorimeter method exothermic test is 8 MJ / m ² or less.   The method for producing a decorative board according to claim 5 or 6, wherein the back surface of the substrate is subjected to an impregnation sealer treatment.   The undercoat layer is a layer made of UV curable paint, and the overcoat layer is acrylic urethane resin paint, acrylic resin paint, epoxy resin paint, polyurethane resin paint, vinyl chloride resin paint, vinylidene chloride resin paint, acrylic silicone resin paint, and fluororesin paint. The method for producing a decorative board according to any one of claims 5 to 7, wherein the layer comprises one or more layers selected from the group consisting of: