JP7705632B2 - Decorative panels - Google Patents

Description

The present invention relates to decorative panels used for interior decoration, etc.

Conventionally, various types of decorative panels have been used as interior finishes for buildings. Examples of decorative panels include decorative panels in which the surface of the substrate is coated with various types of paint such as urethane resin paint, acrylic resin paint, and epoxy resin paint, and decorative panels in which a sheet or film is bonded to the substrate. These decorative panels are prone to scratches and dents when struck by a hard object, and repairs are often difficult, so they are required to have a high surface hardness in order to maintain their design for a long period of time.
On the other hand, in order to ensure safety in the event of a fire or the like, these decorative panels are required to satisfy the standards for non-combustible certification under the Building Standards Act.

One method for improving the surface hardness of a decorative board is to provide a sealer layer on the substrate (Patent Document 1). However, it is difficult to obtain sufficient surface hardness by providing a sealer layer alone. In order to obtain a higher surface hardness, there is also a method for applying a top coat in which glass beads are added to a high-density base paper and a coating film (Patent Document 2). However, this method requires both a high-density base paper and a top coat, and furthermore, depending on the type of substrate to which the sheet is bonded and the type of adhesive used when bonding the substrate and the sheet, there is a problem that the non-combustibility of the laminated decorative board cannot be ensured.
There is also a method for obtaining a coating surface with high hardness using only a top coat (Patent Document 3), but this method requires a baking process, during which the substrate temperature reaches 200 to 300°C, making it difficult to apply this method to ceramic decorative panels that contain organic fibers such as pulp.

JP 2012-210742 A JP 2000-218735 A Japanese Patent Application Publication No. 08-183926

The object of the present invention is therefore to provide a decorative board that has a sufficiently high surface hardness and is non-flammable, without the need for special operations such as gluing a special decorative sheet or baking.

The inventors therefore carried out various investigations to increase the surface hardness while maintaining non-combustibility, and discovered that by forming the outermost decorative layer and/or the decorative layer immediately below it out of multiple decorative layers with a paint composition containing a specific amount of glass beads, a decorative board with significantly improved surface hardness and maintained non-combustibility was obtained, thus completing the present invention.

That is, the present invention provides the following inventions [1] to [5].
[1] A decorative board having two or more decorative layers on at least one surface of a substrate, characterized in that the outermost decorative layer of the plurality of decorative layers and/or the decorative layer immediately beneath it are formed from a coating composition containing glass beads in an amount of 35% by mass or more and 90% by mass or less based on the solid content.
[2] The decorative board according to [1], wherein the average particle size of the glass beads is 5 μm or more and 60 μm or less.
[3] The decorative board according to [1] or [2], wherein the glass beads are spherical or irregular in shape.
[4] The decorative board according to any one of [1] to [3], which is an interior decorative board.
[5] The decorative board according to any one of [1] to [4], wherein the decorative board is a ceramic-based decorative board.

The decorative board of the present invention has a sufficiently high surface hardness that makes it difficult to scratch or dent, and is non-flammable, making it useful as an interior decorative board.

The decorative board of the present invention is a decorative board having two or more decorative layers on at least one surface of a substrate, and is characterized in that the outermost decorative layer of the multiple decorative layers and/or the decorative layer immediately below it are formed from a coating composition containing glass beads in an amount of 35% by mass or more and 90% by mass or less based on the solid content.

As the substrate for the decorative board of the present invention, a substrate for an interior decorative board, particularly a substrate for a ceramic decorative board, is preferred because of its non-combustible properties.
Examples of substrates for ceramic decorative panels include fiber-reinforced cement boards (including calcium silicate boards) used to form the walls of houses, etc., wood-based cement boards, wood wool cement laminates, volcanic glass laminates, extrusion-molded cement boards, slag gypsum boards, lightweight aerated concrete boards, glass boards, ceramic boards, etc.
Of these substrates, fiber reinforced cement boards are more preferred.

These substrates are preferably substrates that use hydraulic cement such as Portland cement as the main raw material for forming the matrix, fibers other than asbestos as the fiber raw material, and admixtures such as wollastonite and calcium carbonate powder as raw materials as necessary, specifically substrates such as fiber-reinforced cement boards specified in JIS A 5430. In particular, 0.8 calcium silicate boards and 1.0 calcium silicate boards, which are types of fiber-reinforced cement boards that use calcareous raw materials and siliceous raw materials as raw materials for forming the matrix and are cured in an autoclave in the curing process, are substrates with excellent flexibility, high strength, and small length change rate due to water absorption, making them suitable as substrates for the ceramic decorative boards of the present invention.

Examples of the fiber raw materials include organic fibers such as pulp, synthetic pulp, polypropylene fiber, rayon fiber, acrylic fiber, vinylon fiber, nylon fiber, and polyester fiber, metal fibers such as steel fiber (steel wire fiber) and amorphous metal fiber, and inorganic fibers such as glass fiber, carbon fiber, rock wool fiber, and whiskers. In the present invention, even when the autoclave curing is adopted, it is preferable to use pulp from the viewpoint of improving the reinforcement and toughness of the decorative board. The pulp referred to here is a state in which cellulose is extracted by mechanically or chemically processing plant raw materials such as wood, and refers to so-called cellulose pulp.
The content of fibers in fiber-reinforced cement boards, particularly organic fibers such as pulp, varies depending on the matrix, but is preferably 5 to 9 mass%, more preferably 6 to 8 mass%, from the viewpoint of ensuring strength and non-combustibility. If the content of organic fibers such as pulp is low, the mechanical strength of the decorative board decreases and cracks due to heat load, drying, carbonation, and impact tend to occur. Conversely, if the content of organic fibers such as pulp is high, it becomes difficult to maintain non-combustibility.

The hydraulic cement may be any one generally used in the art, such as Portland cement.
Various additives used as necessary include those generally used in the industry, and are not particularly limited, but include, for example, powders of wollastonite, mica, calcium carbonate, etc., waste powders of fiber-reinforced cement boards and gypsum boards, etc. When autoclave curing is performed, in order to further increase the strength by hydrothermal reaction hardening with the lime in the cement, it is preferable to add siliceous raw materials, such as crystalline silica such as powdered silica stone, amorphous silica such as fly ash, etc., and also add calcareous raw materials, such as quicklime and slaked lime, as necessary, so that the molar ratio of CaO/ _SiO2 in the matrix component is adjusted to 0.7 to 1.2.

In the present invention, the thickness of the substrate is preferably 3 to 12 mm, more preferably 4 to 8 mm, from the viewpoints of impact resistance, light weight, and ease of application.

In the present invention, the bulk density of the substrate is preferably 0.6 to 1.8 g/cm ³ , and more preferably 0.6 to 1.2 g/cm ³ , from the standpoints of light weight, mechanical strength, and workability.

In the present invention, the total heat generation amount of the substrate is preferably 5 MJ/m ² or less, more preferably 4.7 MJ/m ² or less, from the viewpoint of non-combustibility.

In the present invention, the thickness of the substrate or decorative laminate is a value measured in accordance with JIS A 5430:2013, section 9.2.2 b), and the bulk density is a value measured in accordance with JIS A 5430:2013, section 9.5.
The total heat generation amount of the substrate is a value measured in accordance with JIS A 5430:2013, Annex JA.

The decorative board of the present invention has two or more decorative layers on at least one surface of a substrate.
In the case of interior decorative boards, particularly ceramic decorative boards, the decorative layers are usually formed from the substrate surface in the form of a sealer layer, an undercoat layer, a colored layer, a clear layer, etc. Here, a clear layer may be formed on the colored layer, but an enamel paint containing a pigment may be used as the colored layer, and no clear layer may be formed on the surface.
In the present invention, the outermost decorative layer of the multiple decorative layers and/or the decorative layer immediately below it are formed with a coating composition containing 35% by mass or more and 90% by mass or less of glass beads based on the solid content, so the outermost decorative layer of the present invention usually corresponds to the colored layer or clear layer. The decorative layer immediately below it usually corresponds to the colored layer or undercoat layer. Specifically, when the undercoat layer and/or the colored layer is formed with a coating composition containing the glass beads, the colored layer and/or the clear layer may be formed with a coating composition containing the glass beads. However, when a printed layer is provided between the colored layer and the clear layer described later, the printed layer does not correspond to the decorative layer immediately below.
Furthermore, a colored layer can be overcoated on top of another colored layer, in which case the coating composition containing the glass beads may be used for either the colored layer on the substrate side or the colored layer on the surface side, or for both the colored layer on the substrate side and the colored layer on the surface side. Furthermore, a clear layer formed from a coating composition that may or may not contain glass beads may be provided on a colored layer formed from a coating composition that contains glass beads.
The content of glass beads in the coating composition is the content of glass beads per solid content of the coating composition used to form each of the layers.

Next, the decorative layers, that is, the sealer layer, the undercoat layer, the colored layer, and the clear layer, will be described.
It is preferable to provide a sealer layer between the substrate and the undercoat layer of the decorative sheet, which strengthens the surface layer of the substrate, prevents alkali from eluting to the surface, and improves adhesion to the undercoat layer above it.
The sealer layer can be formed using a known sealer, for example, by applying a curable resin such as a moisture-curing urethane resin or an epoxy resin to the surface of the substrate and curing it. The sealer is preferably a moisture-curing urethane-based sealer that has good impregnation into the substrate, is highly non-volatile, and reacts with moisture in the substrate or moisture in the atmosphere to form three-dimensional crosslinks and has good water resistance, and is mainly composed of a polyisocyanate or a prepolymer having a free isocyanate group, which is a reaction product of a polyisocyanate and a polyol, and a solvent such as butyl acetate. In addition, when yellowing of the decorative plate is a problem, it is preferable to use an aliphatic isocyanate such as HDI (hexamethylene diisocyanate) or an alicyclic isocyanate such as IPDI (isophorone diisocyanate). In addition, in light of recent VOC countermeasures, it is possible to use solvent-free or water-based sealers that do not contain solvents, as well as inorganic sealers such as silicate-based sealers such as lithium silicate or sodium silicate, and silane compound-based sealers whose main components are tetraethoxysilane or tetramethoxysilane.
The sealer layer can be formed, for example, by heating the surface temperature of the fiber-reinforced cement board to 50 to 60° C., applying the sealer by a known method such as a roll coater or spray, and then curing. The viscosity of the impregnating sealer can be appropriately determined taking into consideration the type of impregnating sealer used and the application method, and the curing can be carried out, for example, by drying with heat.
The amount of organic solids in the components of the impregnating sealer is preferably set to 3 to 50 g per unit area (m ² ) of the substrate.

Decorative boards usually have a primer layer on the surface of the sealer layer. By forming a primer layer, the large and small uneven parts and voids on the surface of the substrate are filled with paint, suppressing unevenness and uneven gloss and color caused by paint absorption spots. It also reduces the possibility of defects such as pinholes occurring in the decorative board.

The thickness of the undercoat layer is preferably 5 to 100 μm in terms of the surface smoothness of the decorative board, adhesion to the coating films above and below it, formability, waterproofing, prevention of precipitation of substrate components, prevention of coating pinholes, coating hardening properties, surface foreign matter embedding properties, and ease of film thickness control. A more preferred film thickness is 20 to 90 μm, and even more preferably 25 to 70 μm.
In this specification, the film thickness of a coating layer formed from a coating composition containing glass beads is the thickness of an area having a flat surface that is not affected by protrusions formed by the particles of the glass beads.

From the viewpoints of surface smoothness, chemical resistance, coating adhesion, polishing processability, coating hardness, ease of application, and crack prevention, the coating composition for forming the undercoat layer is preferably an unsaturated polyester-based coating and/or an acrylate-based coating. Specific examples include epoxy acrylate, urethane acrylate, allylic unsaturated polyester such as phthalic acid diallyl ester, maleic acid-based unsaturated polyester obtained by polycondensation of unsaturated dibasic acids such as maleic anhydride and fumaric acid with glycols, polyester monoacrylate having a carboxyl group or a hydroxyl group as a functional group, polyester diacrylate obtained from acrylic acid, a dibasic acid, and a dihydric alcohol, polyester acrylate such as polyester polyacrylate obtained from a polyhydric alcohol having a valence of 3 or more, a dibasic acid, and acrylic acid, oligomers such as epoxy acrylate oligomer, epoxy oligomer, acrylic polyether, polyether acrylate, etc. In addition, it is preferable that the coating composition for forming the undercoat layer be an ultraviolet-curable coating, since it is easy to apply, the coating film cures quickly, and the coating film has excellent abradability and durability, as well as excellent adhesion to the substrate and topcoat coating.

Methods for applying the undercoat paint composition include using a roll coater or a flow coater, among which a roll coater is suitable in terms of the effect of filling the large and small irregularities and voids present on the substrate surface with paint. Also, a flow coater is suitable from the viewpoint of applying the paint evenly.

In the present invention, the amount of organic solids contained in the undercoat layer is preferably from 3 to 70 g, more preferably from 10 to 65 g, and even more preferably from 13 to 60 g per unit area (m ² ) of the substrate.
In this specification, the amount of organic solids contained in the coating layer can be calculated by coating amount (g/m ² )×coating composition solids amount (%)×organic component amount in coating composition solids (%).

The undercoat coating for forming the undercoat layer can be performed once to form an undercoat layer of a predetermined thickness, or it can be performed two or more times to form an undercoat layer of a predetermined thickness. For example, when performing undercoat coating twice to form an undercoat layer of a predetermined thickness, the first undercoat coating is performed with a slightly high viscosity undercoat paint (200 to 600 dPa·s), and the amount of UV irradiation is adjusted so that the undercoat layer is not completely cured. Next, the second undercoat coating is performed with a slightly low viscosity undercoat paint (20 to 60 dPa·s), and then UV irradiation is performed again to completely cure the entire undercoat paint. In this way, the first undercoat coating has the effect of filling large and small uneven parts and voids on the substrate surface with the paint, and the second undercoat coating has a self-leveling effect to obtain a smooth coating surface of the undercoat layer, so that a good undercoat layer can be formed efficiently. In addition, after the undercoat coating is completely cured, it can be polished with a belt sander or the like to form an undercoat layer with an even smoother surface.

A colored layer is formed on the surface of the undercoat layer. The thickness of the colored layer is preferably 5 to 70 μm, more preferably 10 to 65 μm, and even more preferably 15 to 60 μm.

Examples of inorganic color pigments contained in the coating composition for forming the colored layer include titanium oxide, zinc oxide, red iron oxide, yellow ochre, chromium oxide green, iron blue, carbon black, iron black, etc., and it is more preferable to use one or more of them in combination. Also, organic pigments can be used in combination as necessary.
As the paint composition for forming the colored layer, an organic solvent-based paint or a water-based paint can be used, and it is preferable to use a paint containing a resin such as an acrylic resin, a urethane resin, or an acrylic urethane resin having the above-mentioned color pigment, and among them, an acrylic urethane resin paint is suitable, and it is more preferable to use a two-liquid curing acrylic urethane resin paint. In addition, paints such as epoxy resin paint, polyurethane resin paint, vinyl chloride resin paint, vinylidene chloride resin paint, acrylic silicone resin paint, and fluororesin paint may also be used.

The method for forming the colored layer is not particularly limited, and can be selected from known methods used in normal painting, such as the spray method, roll coater method, and flow coater method. Among these, application with a roll coater or flow coater is suitable, and when applying two or more coats, these methods may be used in combination as appropriate.

In the present invention, the amount of organic solids in the components of the colored layer is preferably set to 5 to 40 g per unit area (m ² ) of the substrate, more preferably 10 to 35 g, and even more preferably 10 to 30 g.

The decorative plate may have a clear layer on the surface of the colored layer. The thickness of the clear layer is preferably 1 to 70 μm, more preferably 1 to 65 μm, and even more preferably 3 to 60 μm.

The paint composition for forming the clear layer can be an organic solvent-based paint or a water-based paint, and examples of such paints include colorless and transparent resins made of two-component curing resins such as acrylic silicone, urethane, acrylic, and acrylic urethane resins, thermosetting resins, and other additives such as wetting and dispersing agents, anti-settling agents, defoamers, and leveling agents, and solvents such as butyl acetate and ethyl acetate. Among these, clear paints using acrylic silicone or acrylic urethane resins, which have excellent weather resistance and stain resistance, are preferred.

The coating method for forming the clear layer can be an existing method using a flow coater, roll coater, spray coater, etc. The coating amount of the clear layer in the form of a dry coating is preferably 1 to 160 g, more preferably ² to 140 g, per unit area ( ^m2 ) of the substrate. In addition, the amount of organic solids in the clear layer is preferably 1 to 45 g, more preferably 2 to 35 g, and even more preferably 3 to 30 g, per unit area (m2) of the substrate, from the viewpoint of ensuring non-combustibility.

In the present invention, the outermost decorative layer of the multiple decorative layers and/or the decorative layer immediately below it are formed from a coating composition containing 35% by mass to 90% by mass of glass beads based on the solid content. Specifically, as described above, when the undercoat layer and/or the colored layer are formed from a coating composition containing glass beads, the colored layer and/or the clear layer may be formed from a coating composition containing glass beads.
Of these, in order to maintain better hardness of the decorative plate coating film, it is more preferable to form the colored layer and/or the clear layer with a paint composition containing glass beads, and it is even more preferable to form the colored layer and the clear layer with a paint composition containing glass beads.
Furthermore, by forming a colored layer or a clear layer using a paint composition containing glass beads on top of an existing colored layer formed using a paint composition that does not contain glass beads, the surface hardness can be improved compared to that of a colored layer formed using an existing paint composition that does not contain glass beads.

The glass beads contained in the coating composition used to form these decorative layers may be silicate glass beads, and may be spherical or irregular in shape. These glass beads may be any type, such as for use as a filler, road marking paint, blasting, or crushing/dispersing, and two or more types may be used in combination.
Examples of commercially available glass beads include CF0002, CF0003, CF00017, CF0018, CF0027, CF00033, and CF0093 (manufactured by Takara Standard Co., Ltd.), GB301S, GB731, GB210, EGB063Z, EGB731, EGB210, EMB-20, and EMB-10 (manufactured by Potters Ballotini Co., Ltd.), and UBS-0020L, UBS-0030L, UBS-02L, UBS-0010E, UBS-0020E, UBS-0030E, and UB-02E (manufactured by Unitika Co., Ltd.). These glass beads may be surface-treated with a silane coupling agent such as aminosilane, glycidoxysilane, or acrylic silane.
In addition, from the viewpoint of the effect of improving the hardness of the decorative board coating film, the average particle size of the glass beads is preferably 5 μm or more and 60 μm or less, more preferably 5 μm or more and 50 μm or less, even more preferably 5 μm or more and 45 μm or less, and even more preferably 10 μm or more and 40 μm or less.
Here, the average particle size of the glass beads is an average particle size measured by employing, for example, a measurement method using image analysis of images taken with an electron microscope, a sieving method, a Coulter counter method, an electrical detection zone method, a sedimentation method, or the like.
In this specification, the average particle size (primary particle size) of the glass beads was determined by observation with a scanning electron microscope (SEM). Specifically, 50 randomly selected glass beads were observed with a scanning electron microscope, and the maximum diameter was determined as the particle size of the glass beads, and the average value of these was determined as the average particle size. The maximum diameter was determined by drawing a straight line connecting any two points on the circumference of the glass beads in the SEM image, determining the point where the length of the straight line is maximum, and measuring the length of the straight line at that point as the maximum diameter.

The content of glass beads per solid content in the coating composition forming the outermost decorative layer or the decorative layer immediately below it is set to 35% by mass or more and 90% by mass or less in order to improve the coating film hardness of the decorative board. If it is less than 35% by mass, a sufficient effect of improving the coating film hardness cannot be obtained, and if it exceeds 90% by mass, it becomes difficult to form the decorative layer. The content of glass beads per solid content in the coating composition forming each decorative layer is preferably 37% by mass or more and 85% by mass or less, more preferably 40% by mass or more and 85% by mass or less, even more preferably 45% by mass or more and 85% by mass or less, and even more preferably 50% by mass or more and 80% by mass or less.
More specifically, when glass beads are contained in the coating composition forming the colored layer, the preferred content of the glass beads per solid content is 35% by mass or more and 70% by mass or less, more preferably 45% by mass or more and 60% by mass or less, and even more preferably 50% by mass or more and 55% by mass or less. When glass beads are contained in the coating composition forming the clear layer, the preferred content of the glass beads per solid content is 50% by mass or more and 90% by mass or less, more preferably 60% by mass or more and 85% by mass or less, and even more preferably 65% by mass or more and 80% by mass or less.
In addition, the total content per solid content of glass beads in the coating composition forming both the outermost decorative layer and the decorative layer immediately below it is preferably 30% by mass or more and 85% by mass or less, more preferably 30% by mass or more and 80% by mass or less, even more preferably 30% by mass or more and 75% by mass or less, and even more preferably 30% by mass or more and 70% by mass or less, from the viewpoint of improving the coating film hardness of the decorative board.

In addition, in the decorative board of the present invention, a printed layer can be provided between the colored layer and the clear layer. By providing a printed layer, a pattern such as a wood grain or stone grain can be imparted to the decorative board. As a printing method, existing methods such as gravure printing, gravure offset printing, inkjet printing, screen printing, rotary screen printing, letterpress printing, and pad printing can be applied.

The decorative board of the present invention preferably has a total heat generation amount of 8 MJ/ ^m2 or less according to a cone calorimeter heat generation test. By satisfying this requirement, the decorative board satisfies the heat generation class 1 (heating time 20 minutes) specified in JIS A 5430:2013, Appendix JA, and exhibits high non-combustibility. More preferably, the total heat generation amount is 7.2 MJ/ ^m2 or less.

The present invention will now be described in more detail with reference to the following examples, but the present invention is not limited to these examples in any way.

[Materials used]
(1) Glass beads (silicate glass) Average particle size: 10 μm, 20 μm, and 40 μm
(2) Glass beads (silicate glass, aminosilane surface treatment) Average particle size: 10 μm
(3) Substrate: 0.8 calcium silicate board

(4) Paints A. Urethane sealer (impregnating sealer)
A. Acrylic epoxy UV curing paint (UV undercoat paint)
C. Enamel paint (forms a colored layer)
The enamel paint is a two-component curing acrylic urethane paint.
D. Clear paint (forms a clear layer)
The clear paint is a two-component curing acrylic urethane paint.

[Method of forming decorative layer]
Example 1
The surface of the substrate was polished and smoothed using a belt sander, and then an impregnating sealer was applied to the surface at about 30 g/m ² using a roll coater.
On the impregnating sealer layer, about 120 g/ ^m2 of undercoat paint was applied in two separate applications using a roll coater, cured by exposure to ultraviolet light, and then polished using a belt sander to form a smooth undercoat layer.
Onto the undercoat layer, approximately 100 g/ ^m2 of enamel paint containing glass beads was applied using a flow coater, and then the paint was dried and hardened in a dryer at 90°C for 20 minutes to form a colored layer, thereby obtaining a decorative board.

Example 2
After forming an undercoat layer using the same process as in Example 1, approximately 100 g/ ^m2 of enamel paint not containing glass beads was applied onto the undercoat layer using a flow coater, and then the paint was dried and hardened in a dryer at 90°C for 20 minutes to form a colored layer. Furthermore, a colored layer containing glass beads was formed using the same process as in the colored layer, and a decorative panel was obtained.

Example 4
After forming an undercoat layer using the same process as in Example 1, approximately 100 g/ ^m2 of enamel paint containing glass beads was applied onto the undercoat layer using a flow coater, and the paint was dried and cured in a dryer at a 90°C atmosphere for 20 minutes to form a colored layer. After that, approximately 75 g/ ^m2 of clear paint not containing glass beads was applied using a flow coater, and the paint was dried and cured in a dryer at a 90°C atmosphere for 20 minutes to form a clear layer, and a decorative panel was obtained.

Example 11
After forming an undercoat layer using the same process as in Example 1, approximately 100 g/ ^m2 of enamel paint containing glass beads was applied onto the undercoat layer using a flow coater, and the paint was dried and cured in a dryer at a 90°C atmosphere for 20 minutes to form a colored layer. After that, approximately 10 g/ ^m2 of clear paint not containing glass beads was applied using a roll coater, and the paint was dried and cured in a dryer at a 90°C atmosphere for 20 minutes to form a clear layer, and a decorative panel was obtained.

Examples 3, 5 to 10, 12 to 17 and Comparative Example 1
Decorative panels were obtained by the same process as in Examples 1, 2 and 4 described above, adjusting the type and content of glass beads, and the type and amount of paint applied.

[Test Method]
The hardness of the coating surface was measured according to the "JIS K 5400 pencil scratch test." A hardness of 7H or more was considered to be acceptable.
The total heat generation amount after 20 minutes of heating was measured according to the heat generation test (cone calorimeter heat generation test) specified in "JIS A 5430:2013, Annex JA".
The appearance was evaluated by visually observing the outermost decorative layer from a distance of 1 m to check for unevenness, streaks, etc. A good appearance was evaluated as ◯, and a slightly annoying appearance was evaluated as △.

[result]
The measurement results are shown in Tables 1 and 2. The glass bead content in the tables indicates the glass bead content (mass %) per solid content in the coating composition forming each coating film.

As can be seen from Table 1, when a paint composition without added glass beads is used as in Comparative Example 1, the hardness of the coating film on the decorative board is 3H, whereas when the outermost decorative layer (clear layer) and/or the decorative layer immediately below it (colored layer) are formed with a paint composition containing 35 to 90 mass % glass beads (average particle diameter 20 μm), the hardness of the coating film on the decorative board is 7H or more, a significant improvement.
Also, as shown in Table 2, the same effect can be obtained if the average particle size of the glass beads contained is 10 to 40 μm. If the average particle size of the glass beads is 40 μm, the hardness of the coating film of the decorative board is 9H, but the large particle size makes the appearance somewhat less beautiful.
Furthermore, when both the colored layer and the clear layer are formed using a paint composition containing glass beads, the hardness of the coating film of the decorative board is improved, and in an embodiment where the hardness of the coating film is more significantly improved, a hardness of 9H is obtained.
Regarding the heat generation test results, even in Example 8, which had the highest organic solid content, the heat generation was about 6.6 MJ/ ^m2 , and even in Examples with lower organic solid contents, the heat generation was sufficiently in the first class.

Claims (4)

A decorative board having two or more decorative layers on at least one surface of a substrate, the outermost decorative layer of the plurality of decorative layers and/or the decorative layer immediately below it being formed of a coating composition containing glass beads in an amount of 35% by mass or more and 90% by mass or less based on the solid content,
The average particle size of the glass beads is 10 μm or more and 40 μm or less,
The decorative board, wherein the thickness of the plurality of decorative layers is 15 to 60 μm. 2. The decorative laminate of claim 1 , wherein said glass beads are spherical or irregular in shape. 3. The decorative board according to claim 1 or 2 , which is an interior decorative board. The decorative board according to any one of claims 1 to 3 , which is a ceramic decorative board.