JP7607690B2 - Painted body - Google Patents

Description

The present invention relates to a painted body, and in particular to a painted body that has a transparent layer that does not hide the design of the base, and has a matte finish and a calm, heavy feel.

Architectural exterior wall materials are coated with paint to impart design and weather resistance to the surface. Clear coatings that transmit visible light can bring out the design of the base or substrate, and are often formed as a surface protective layer to protect the design surface. However, especially in recent years, values regarding the exterior walls of houses have become more diverse, and a matte finish that reduces gloss and gives a calm look and has a heavy feel is becoming more popular.

JP 2000-256578 A (Patent Document 1) describes an invention for an architectural exterior wall panel in which a transparent or translucent synthetic resin paint containing aggregate with an average particle size of 30 to 100 μm is applied to the surface of the architectural exterior wall panel, which has been coated with a colored opaque paint, and in which the 60° specular gloss of the flat portion of the painted panel surface is in the range of 1 to 6. It claims that this makes it possible to provide an architectural exterior wall panel that can maintain a matte coating surface for a long period of time without causing the phenomenon of pigments separating out from the coating surface (chalking).

JP 2005-187701 A (Patent Document 2) describes an invention for a transparent water-based matte paint composition that is characterized by containing (A) a synthetic resin emulsion, (B) resin beads with a specific gravity of 1.0 to 1.5, and (C) a wax with a specific gravity of 0.7 to less than 1.0. This water-based matte paint composition is said to have excellent storage stability, be able to suppress uneven gloss in the formed coating film, have an excellent matte effect, and further provide excellent water resistance and transparency in the formed coating film.

JP 2013-208513 A (Patent Document 3) describes an invention for a method for forming a matte multilayer film for ceramic building materials, in which an enamel coating film and a matte clear coating film are formed in that order on the ceramic building material, and uses a matte clear paint for ceramic building materials that contains a specific ratio of light-transmitting granular material (a) with a median diameter (D50) of 2 to 10 μm, light-impermeable granular material (b) with a median diameter (D50) of 50 to 200 μm, and binder resin (c). It claims that this method can suppress blocking without compromising transparency, and can provide a method for forming a matte multilayer film for ceramic building materials that makes repaired areas less noticeable when repaired.

JP 2000-256578 A JP 2005-187701 A JP 2013-208513 A

Patent documents 1 to 3 all describe techniques for suppressing the gloss of the surface of a painted body using a clear layer, but because the clear layer itself is a layer that is prone to becoming glossy, the matte effect of the clear layer cannot be said to be sufficient.

Therefore, the object of the present invention is to provide a painted body that has a transparent layer that does not hide the design of the base, and has a matte finish that gives it a calm and profound look.

The inventors have investigated ways to enhance the matte effect of the clear layer by using light-transmitting granular matter having a median diameter (D50) that is expected to provide a matte effect, and when the proportion of the light-transmitting granular matter contained in the clear layer was increased, the clear layer became cloudy and transparency was reduced. Next, instead of increasing the proportion of the light-transmitting granular matter contained in the clear layer, they investigated whether the matte effect could be enhanced by making the clear layer thicker, but they encountered the problem that the matte effect was reduced when the clear layer was made thicker. They confirmed that in thick-film coating, the light-transmitting granular matter tends to sink into the coating film, and the amount of light-transmitting granular matter present on the coating film surface is reduced, which tends to reduce the matte effect. Therefore, the inventors discovered that by stacking two or more clear layers containing light-transmitting granular matter with a median diameter (D50) expected to provide a matte effect while controlling the proportion of light-transmitting granular matter contained in the clear layer and the film thickness of the clear layer, it is possible to provide a clear layer that maintains a transparency that does not hide the design of the base, while also providing a matte, calm, and heavy feel, and thus completed the present invention.

The coated body of the present invention is therefore a coated body comprising a substrate and at least two clear layers, each of which contains light-transmitting granular matter having a median diameter (D50) of 10 to 200 μm, the amount of the light-transmitting granular matter contained in each clear layer being 35 mass% or less, and the average film thickness of each of the at least two clear layers being 80 μm or less.

In a preferred embodiment of the coated body of the present invention, the average film thickness of the at least two clear layers is 20 μm or more.

In another preferred embodiment of the coated body of the present invention, the 60 degree gloss value of the surface of the coated body is 20 or less.

In another preferred embodiment of the coated body of the present invention, at least one of the at least two clear layers contains light-opaque granular material.

The present invention makes it possible to provide a painted body that has a transparent appearance that does not conceal the design of the base, and has a matte, calm, and heavy-looking clear layer.

The present invention is described in detail below. The present invention relates to a coated body comprising a substrate and at least two clear layers containing light-transmitting granular matter having a median diameter (D50) of 10 to 200 μm, but in which the amount of the light-transmitting granular matter does not exceed 35 mass %. In this specification, this coated body is also referred to as the "coated body of the present invention."

In this specification, a coated body means a substrate having at least two clear layers coated on at least a portion of its surface. In the present invention, the at least two clear layers may be formed directly on the substrate, or a further layer such as a design layer may be present between the clear layer and the substrate, and the at least two clear layers may be formed on the substrate via the further layer.

In this specification, substrate refers to the object onto which at least two clear layers are applied.

In this specification, a clear layer means a layer having a visible light transmittance of 5% or more, and the light transmittance of the clear layer is preferably 10% or more, and particularly preferably 15% or more. The clear layer may be a colorless layer or a colored layer. The coated body of the present invention contains light-transmitting granular matter having a median diameter (D50) of 10 to 200 μm, but is a coated body having two or more clear layers in which the amount of the light-transmitting granular matter does not exceed 35 mass%, and may further have a clear layer other than the clear layer. For convenience, in this specification, "a clear layer that contains light-transmitting granular matter with a median diameter (D50) of 10 to 200 μm, but the amount of the light-transmitting granular matter does not exceed 35 mass%" is also referred to as the "first clear layer," and "a clear layer other than the clear layer that contains light-transmitting granular matter with a median diameter (D50) of 10 to 200 μm, but the amount of the light-transmitting granular matter does not exceed 35 mass%" is also referred to as the "second clear layer."

In this specification, visible light transmittance means total light transmittance in the visible region (360 nm to 750 nm) and can be measured in accordance with JIS K 7375:2008.

In this specification, a design layer means a layer intended to apply a design to a substrate. Here, the design refers to a shape, pattern, or color, or a combination of these. The substrate (particularly concrete, wood, etc.) can utilize its own design, but it is also possible to apply a design layer to the substrate. The design layer may be formed from, for example, paint or ink, or, when applying a design using wallpaper, film, etc., it is also possible to apply the design layer to the substrate by attaching these to the substrate.

As described above, the coated body of the present invention includes light-transmitting granular matter having a median diameter (D50) of 10 to 200 μm, but has two or more clear layers (i.e., first clear layers) in which the amount of light-transmitting granular matter does not exceed 35 mass%. By adjusting the average film thickness of each of the first clear layers constituting the coated body of the present invention so as not to exceed 80 μm, it is possible to form a clear layer that has a sense of transparency that does not hide the design of the base, and has a calm, heavy-looking matte finish.

The coated body of the present invention may not include another layer between the first clear layers (i.e., the first clear layers are directly laminated to form a laminate structure), or may have a second clear layer between the first clear layers. However, the coated body of the present invention does not include a light-opaque layer between the first clear layers. In this specification, a light-opaque layer means a layer with a visible light transmittance of less than 5%.

In this specification, a light-transmitting granular material means a granular material having a visible light transmittance of 30% or more, and the light transmittance of the light-transmitting granular material is preferably 40% or more, and particularly preferably 50% or more.

The light-transmitting granular material is a material that can achieve a matte effect while maintaining transparency, but the particle size is important in achieving the matte effect. If the light-transmitting granular material is too large, it becomes difficult to achieve a matte finish, so the light-transmitting granular material used in the first clear layer has a median diameter (D50) of 10 to 200 μm, preferably 10 to 50 μm, and more preferably 10 to 20 μm. It is particularly preferable that the particle size of the light-transmitting granular material is approximately the same as the average film thickness of the first clear layer, or slightly smaller than the average film thickness of the first clear layer.

In this specification, the median diameter (D50) of the granular material refers to the 50% particle diameter ( _D50 ) of the volume-based particle size distribution of the granular material dispersed in the clear layer, and can be obtained from the particle size distribution measured using a particle size distribution measuring device (e.g., a laser diffraction/scattering type particle size distribution measuring device). The particle diameter is expressed as a sphere-equivalent diameter measured by the laser diffraction/scattering method.

It is preferable that the specific gravity of the light-transmitting granules is 1.1 to 2.6.

Examples of light-transmitting granular materials include resin beads and glass beads. The light-transmitting granular materials may be used alone or in combination of two or more types.

The amount of light-transmitting granular matter having a median diameter (D50) of 10 to 200 μm contained in each first clear layer constituting the coated body of the present invention is 35% by mass or less. If the amount of light-transmitting granular matter in each first clear layer is large, the clear layer tends to become cloudy and lose the transparency that does not hide the design of the base. In addition, the amount of light-transmitting granular matter having a median diameter (D50) of 10 to 200 μm contained in the first clear layer is preferably 5 to 35% by mass, more preferably 7 to 30% by mass, and particularly preferably 10 to 25% by mass. From the viewpoint of ensuring a sufficient matte effect, the amount of the light-transmitting granular matter in the first clear layer is preferably 5% by mass or more. In addition, if the amount of the light-transmitting granular matter in the first clear layer exceeds 35% by mass, the extensibility of the clear layer decreases, and sufficient physical properties such as frost resistance and weather resistance may not be obtained.

The coated body of the present invention has at least two first clear layers, and the average thickness of each first clear layer is 80 μm or less. When a clear layer is formed by painting a thick film, the light-transmitting granular matter sinks into the clear layer, reducing the amount of light-transmitting granular matter present on the surface of the clear layer and tending to reduce the matte effect, so the average thickness of each first clear layer is adjusted to 80 μm or less. The average thickness of the first clear layer is preferably 10 to 60 μm, and more preferably 20 to 50 μm.

In this specification, the average film thickness of the clear layer is a value determined by observing the cross section of the coating film with a scanning electron microscope or optical microscope, and is calculated as the average value of the measurement results of 100 points randomly selected from the captured image.

In the coated body of the present invention, the average thickness of the entire first clear layer is preferably 20 μm or more, more preferably 20 to 120 μm, and even more preferably 40 to 100 μm. By making the average thickness of the entire first clear layer 20 μm or more, it is possible to prevent water stains from occurring on the substrate. Water stains are a phenomenon in which water penetrates the substrate when water is splashed on the coated body, causing the substrate to turn a wet color, and there is a problem that this can cause poor appearance due to rain after construction and deterioration of the substrate. Although the clear layer itself is essentially water-resistant, there is a possibility that the barrier properties will be lost due to variations in film thickness due to unevenness of the substrate and wear of the layer over time. For this reason, by setting the average thickness of the entire first clear layer to a certain level or more, specifically 20 μm or more, it is possible to maintain a stable barrier property against water even after aging, and to suppress water stains. The average thickness of the entire first clear layer may be obtained by adding up the average thicknesses of the first clear layers, or may be obtained by directly measuring the average thickness of the entire first clear layer.
In the coated body of the present invention, if the average film thickness of the entire first clear layer is less than 10 μm, the frost resistance may be poor when used as an exterior wall material in cold regions.

In the coated body of the present invention, it is preferable that the average film thickness of the first clear layer and the median diameter (D50) of the light-transmitting granules contained in the first clear layer satisfy the following relationship.
(Relationship) 0.05<Average film thickness/Median diameter (D50)<8
In the formula, the average film thickness is the average film thickness (μm) of the first clear layer, and the median diameter (D50) is the median diameter (D50) (μm) of the light-transmitting particulate matter contained in the first clear layer.
If the value of the average film thickness/median diameter (D50) in the first clear layer is too large, the matte appearance may be lost, whereas if it is too small, the matte performance may not be obtained.
It is preferable that all of the first clear layers constituting the coated body of the present invention satisfy the above relational expression.

In the coated body of the present invention, at least one of the at least two first clear layers preferably contains a light-opaque granular material. By using a light-opaque granular material in the first clear layer, a more matte finish can be obtained compared to a clear layer consisting only of light-transmitting granular material. All of the first clear layers constituting the coated body of the present invention may contain a light-opaque granular material.

In this specification, light-opaque granular material means granular material with a visible light transmittance of less than 20%.

The median diameter (D50) of the light-opaque granular material is preferably 1 to 10 μm, more preferably 2 to 7 μm, and particularly preferably 3 to 6 μm.

It is preferable that the optically opaque granular material has a specific gravity of 1.1 to 4.5.

Examples of light-opaque granular materials include silica, calcium carbonate, silica, alumina, hydrated alumina, magnesia, talc, clay, barium sulfate, barium carbonate, wollastonite, ceramic powder, etc. Light-opaque granular materials may be used alone or in combination of two or more types.

When the first clear layer contains light-opaque granular matter, the amount of light-opaque granular matter contained in the first clear layer is preferably 0.1% to 10% by mass, more preferably 0.5% to 5% by mass. If the amount of light-opaque granular matter is too large, the transparency of the coating film may be impaired and the viscosity of the paint may increase, reducing the ease of painting. Furthermore, when the light-opaque granular matter is silica, if the amount of light-opaque granular matter is too large, it may reduce the warm water resistance.

In the coated body of the present invention, the first clear layer is preferably a coating film formed from an emulsion paint. Emulsion paint is a paint containing an emulsion resin, and emulsion resin refers to a resin obtained by emulsion polymerization among water-dispersible resins. When the coated body of the present invention is a coated body that makes use of the design of the substrate, if the first clear layer is a coating film formed from an emulsion paint, the occurrence of wet color on the substrate can be suppressed. This is because, in the case of a resin dissolved in a medium, when applied to a substrate, it impregnates the substrate to the fine details and completely fills the voids, reducing light scattering and making the substrate darker overall (wet color), whereas in the case of emulsion paint, the resin has a certain particle size, so it does not impregnate the substrate to the fine details compared to dissolved resin, and it is possible to leave a moderate amount of voids in the substrate, which is thought to suppress wet color.

For emulsion paints that can be suitably used to form the first clear layer, the median diameter (D50) of the resin dispersed in the emulsion paint is, for example, 70 to 200 nm.

In this specification, the median diameter (D50) of a resin refers to the 50% particle diameter ( _D50 ) of the volume-based particle size distribution of the resin dispersed in the coating material, and can be determined from the particle size distribution measured using a particle size distribution measuring device (e.g., a laser diffraction/scattering type particle size distribution measuring device). The particle diameter is expressed as a sphere-equivalent diameter measured by the laser diffraction/scattering method.

In addition, when the emulsion paint suitable for forming the first clear layer is an acrylic resin-based emulsion paint, the monomers constituting the acrylic resin do not contain aromatic monomers such as styrene, or, even if they contain aromatic monomers, the proportion of aromatic monomers is preferably 5% by mass or less of the total constituent monomers. In order to form a clear layer, it is preferable not to use aromatic monomers such as styrene, which have poor weather resistance, as the constituent monomers of the acrylic resin. If the proportion of aromatic monomers such as styrene exceeds 5% by mass of the total constituent monomers, the weather resistance may be poor when used outdoors.

The 60-degree gloss value of the surface of the coated body of the present invention is preferably 20 or less, more preferably 1 to 20, even more preferably 2 to 15, and particularly preferably 3 to 10. The 60-degree gloss value is a gloss value for light with an incident angle of 60°, and is therefore an index of the specular gloss when the surface of the coated body is viewed relatively from the front. The 85-degree gloss value of the surface of the coated body of the present invention is preferably 0.5 to 15, more preferably 1 to 10, and even more preferably 1.5 to 5. The 85-degree gloss value is a gloss value for light with an incident angle of 85°, and is therefore an index of the specular gloss when the surface of the coated body is viewed relatively from a horizontal direction. The ratio of the 60-degree gloss value of the surface of the coated body of the present invention to the 85-degree gloss value (60-degree gloss value/85-degree gloss value) is preferably 1 to 10, more preferably 1 to 7, and even more preferably 1 to 4. The smaller the 60 degree gloss value/85 degree gloss value, the smaller the difference in appearance when the surface of the coated body is viewed from the front and from a horizontal direction.

In this specification, the surface of the coated body for which the gloss value is measured is a surface coated with at least two first clear layers and, if necessary, further layers. In this specification, the gloss value is the specular gloss defined in JIS K5600-4-7 (ISO 2813:1994), and can be measured, for example, using a gloss meter VG-2000 manufactured by Nippon Denshoku Co., Ltd.

In the coated body of the present invention, examples of the substrate include plastic substrates such as epoxy resin, ABS resin, polycarbonate, polyvinyl chloride, polystyrene, acrylic resin, particularly polymethyl methacrylate (PMMA), polyethylene terephthalate (PET), and polypropylene (PP), metal substrates such as iron, stainless steel, aluminum, copper, titanium, and alloys thereof, inorganic substrates other than metals such as cement, concrete, gypsum, calcium silicate, calcium carbonate, marble, artificial marble, glass, and ceramic, paper-based substrates, wood substrates, and composite substrates combining two or more of these substrates.

The shape of the substrate may be, for example, a film, a sheet, or a plate. The surface of the substrate may be smooth or may have irregularities.

Specific examples of the substrate include wood building materials such as veneer, plywood, particle board, and medium density fiberboard (MDF); ceramic building materials such as ceramic siding board, flexible board, calcium silicate board, gypsum slag barite board, wood chip cement board, asbestos cement board, pulp cement board, precast concrete board, lightweight aerated concrete (ALC) board or ALC panel, and gypsum board; various building materials (particularly building boards) such as metal siding board, and metal building materials such as aluminum, iron, and stainless steel. Specific examples of the substrate include plastic substrates such as PVC sheets, tarpaulin, plastic cardboard, and acrylic boards; papers such as coated paper (specifically resin-coated paper), art paper, cast paper, lightly coated paper, fine paper, synthetic paper, and inkjet paper; tiles, glass plates, and the like.

The surface of the substrate may be subjected to pretreatment such as degreasing, chemical conversion treatment, and polishing, or may be coated with a sealer or primer. For example, if the substrate is a substrate (particularly a porous substrate) that may excessively absorb paint or ink, such as a ceramic building material, the substrate surface may be coated with a sealer and a sealer layer may be formed on the substrate. Also, if the substrate is a metal building material, the substrate surface may be coated with a primer and a primer layer may be formed on the substrate.

In the coated body of the present invention, the layer in contact with the substrate preferably contains glycidyl groups. The glycidyl groups present in the layer in contact with the substrate can improve adhesion to the substrate. For example, by forming a coating film using a resin having glycidyl groups, it is possible to form a layer containing glycidyl groups, particularly a layer containing a resin having glycidyl groups, on the substrate.

In the coated body of the present invention, a sealer layer may be formed between the substrate and the first clear layer. In one embodiment of the coated body of the present invention, the coated body may include a substrate, a sealer layer, and at least two first clear layers. Here, the sealer layer is located on the substrate, and the first clear layer is located on the sealer layer. A sealer known in the paint industry may be used to form the sealer layer. In addition, when the coated body further includes a design layer, the design layer may be disposed between the substrate and the sealer layer, or between the sealer layer and the first clear layer.

In addition, in cases where a sealer layer is required when painting a substrate, it is preferable to further form a water-repellent layer from the viewpoint of suppressing the occurrence of water stains due to the clear layer. In one embodiment of the coated body of the present invention, the coated body can include a substrate, a sealer layer, a water-repellent layer, and at least two first clear layers. Here, the sealer layer is located on the substrate, the water-repellent layer is located on the sealer layer, and the first clear layer is located on the water-repellent layer. In addition, in cases where the coated body further includes a design layer, the design layer can be disposed between the substrate and the sealer layer, or between the water-repellent layer and the first clear layer. Here, the water-repellent layer is a layer containing a water-repellent agent such as a silicone-based water-repellent agent, and the contact angle of the water-repellent layer after painting is preferably 70 degrees or more.

In this specification, the contact angle of the water-repellent layer refers to the contact angle between the water-repellent layer surface and water, determined by the sessile drop method. Specifically, 10 μL of distilled water is dropped onto the water-repellent layer surface, and left to stand for 10 seconds in an atmosphere at 20°C, and the contact angle between the water-repellent layer surface and water can be measured using a general contact angle meter (e.g., Kyowa Interface Science Co., Ltd. Contact Angle Meter DMs-401).

In the coated body of the present invention, at least two first clear layers may have further layers formed thereon, such as a photocatalyst layer, a second clear layer, and an overcoat layer. In one embodiment of the coated body of the present invention, the coated body may include a substrate, at least two first clear layers, and at least one further layer selected from a photocatalyst layer, a second clear layer, and an overcoat layer. Here, the first clear layer is located on the substrate, and the further layer is located on the first clear layer. In addition, at least one further layer selected from a sealer layer, a water-repellent layer, a design layer, and the like, as described above, may be disposed between the substrate and the first clear layer.

The photocatalytic layer is a layer containing a material that exhibits photocatalytic activity when irradiated with light such as sunlight. Examples of materials that exhibit photocatalytic activity include metal oxides such as anatase-type titanium oxide, rutile-type titanium oxide, tin oxide, zinc oxide, and cerium oxide, but are not limited to these materials. In addition, the overcoat layer generally refers to the layer that is applied to the outermost surface (in other words, the layer that is disposed at the position furthest from the substrate), but in this specification, when the coated body of the present invention has an additional layer on the first clear layer and the layer applied to the outermost surface at that time is a layer other than the photocatalytic layer or the second clear layer, the layer disposed on the outermost surface is referred to as the overcoat layer. The average film thickness of the overcoat layer is generally several μm or less, for example, about 0.1 to 1 μm.

Next, we will explain the details of a coating composition that can be suitably used to form the first clear layer. In this specification, this coating composition is also referred to as the "coating composition for the first clear layer."

The coating composition for the first clear layer contains a water-dispersible resin and a light-transmitting granular material, and preferably further contains a light-opaque granular material. The light-transmitting granular material and the light-opaque granular material are as described above.

In this specification, the term "water-dispersible resin" refers to a resin that can be distributed in water to form a heterogeneous system (e.g., an emulsion or suspension). The water-dispersible resin preferably contains an emulsion resin. The emulsion resin is a water-dispersible resin that can have a large molecular weight and also has excellent dispersion stability. The water-dispersible resin is preferably contained in the coating composition so that the amount of the water-dispersible resin in the first clear layer is 30 to 95% by mass. The amount of the water-dispersible resin in the first clear layer is more preferably 40 to 90% by mass, and even more preferably 50 to 85% by mass. The water-dispersible resin may be used alone or in combination of two or more types.

The water-dispersible resin preferably contains a water-dispersible resin containing an acrylic component as a constituent element (repeating unit, etc.). In this specification, "acrylic component" refers to acrylic acid, methacrylic acid and derivatives thereof (for example, compounds having a (meth)acryloyl group such as esters and amides of acrylic acid and methacrylic acid, acrylic acid nitrile, methacrylic acid nitrile, etc.). The acrylic component may be used alone or in combination of two or more types.

In this specification, the term (meth)acryloyl means methacryloyl or acryloyl. In addition, in this specification, the term (meth)acrylate means methacrylate or acrylate. For example, 2-ethylhexyl (meth)acrylate is 2-ethylhexyl acrylate or 2-ethylhexyl methacrylate. In addition, a prefix indicating a plural number may be added to the (meth)acrylate, such as di(meth)acrylate, tri(meth)acrylate, etc., in which case each (meth)acrylate may be the same or different.

Water-dispersible resins that contain acrylic components as a constituent element include acrylic resins as well as various modified resins such as acrylic styrene resins, acrylic silicone resins, fluorine-modified acrylic resins, fatty acid-modified acrylic resins, urethane-modified acrylic resins, and epoxy-modified acrylic resins.

The water-dispersible resin may contain a non-acrylic component as a constituent (repeating unit, etc.). The non-acrylic component is a component other than the acrylic component, and examples thereof include, in addition to styrene, carboxyl group-containing monomers such as fumaric acid, maleic acid, maleic anhydride, itaconic acid, itaconic anhydride, crotonic acid, and vinyl versatic acid; aromatic monomers such as methylstyrene, chlorostyrene, methoxystyrene, and vinyltoluene; olefin monomers such as ethylene and propylene; vinyl monomers such as vinyl acetate and vinyl chloride; amide monomers such as maleic acid amide; alkoxysilyl group-containing monomers such as vinyltrimethoxysilane, vinyltriethoxysilane, vinylmethyldimethoxysilane, and vinylmethyldiethoxysilane; dialkyl fumarate, allyl alcohol, vinylpyridine, and butadiene.

The water-dispersible resin can be obtained by polymerization of the constituent monomer components, and is preferably obtained by emulsion polymerization of the constituent monomer components. The monomer components may be used alone or in combination of two or more.

The coating composition for the first clear layer may further contain at least one selected from the group consisting of an ultraviolet absorber and a radical scavenger.

UV absorbers have the effect of absorbing UV rays and preventing deterioration caused by UV rays. Examples of UV absorbers include benzophenone-based UV absorbers, benzoate-based UV absorbers, benzotriazole-based UV absorbers, triazine-based UV absorbers (particularly hydroxyphenyltriazine-based UV absorbers), and benzylidene camphor-based UV absorbers. The UV absorbers may be used alone or in combination of two or more.

Examples of ultraviolet absorbers include 2,4-dihydroxybenzophenone, 2-hydroxy-4-methoxybenzophenone, 2-hydroxy-4-methoxybenzophenone-5-sulfonic acid, 2-hydroxy-4-octoxybenzophenone, 2-hydroxy-4-dodecyloxybenzophenone-2-hydroxy-4-benzyloxybenzophenone, bis(5-benzoyl-4-hydroxy-2-methoxyphenyl)methane, 2,2'-dihydroxy-4-methoxybenzophenone, 2,2'-dihydroxy-4,4'-dimethoxybenzophenone, 2,2',4,4'-tetrahydroxybenzophenone, 2-hydroxy-4-methoxy-2'-carboxybenzophenone, 2-(2'-hydroxy-5'-methylphenyl )benzotriazole, 2-[2'-hydroxy-3',5'-bis(α,α-(dimethylbenzyl)phenyl]benzotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)benzotriazole, 2-(2'-hydroxy-3'-t-butyl-5'-methylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-t-butylphenyl)-5-chlorobenzotriazole, 2-(2'-hydroxy-3',5'-di-t-amylphenyl)benzotriazole, 2-(2'-hydroxy-5'-t-octylphenyl)benzotriazole, 2,2'-methylene-bis[4-(1,1,3,3-tetramethylbutyl)-6-(2N-benzotriazol-2-yl)phenol methyl-3-[3-t-butyl-5-(2H-benzotriazol-2-yl)-4-hydroxyphenyl]propionate and polyethylene glycol condensation product, 2-(2-hydroxyphenyl)benzotriazole, 2-(2'-hydroxy-5'-methylphenyl)benzotriazole, 2,6-di-t-butylphenyl-3',5'-di-t-butyl-4'-hydroxybenzoate, hexadecyl-3,5-di-t-butyl-4-hydroxybenzoate, 2-[4-[(2-hydroxy-3-dodecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-tridecyloxypropyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2-[4-[(2-hydroxy-3-(2'-ethyl)hexyl)oxy]-2-hydroxyphenyl]-4,6-bis(2,4-dimethylphenyl)-1,3,5-triazine, 2,4-bis(2-hydroxy-4-butyloxyphenyl)-6-(2,4-bis-butyloxyphenyl)-1,3,5-triazine, hydroxyphenyl triazine, 2-(2-hydroxy-4-[1-octyloxycarbonylethoxy]phenyl)-4,6-bis(4-phenylphenyl)-1,3,5-triazine, 2,4,6-tris(2-hydroxy-4-hexyloxy-3-methylphenyl)-1,3,5-triazine, etc.

The radical scavenger can capture free radicals and improve light stability. In the present invention, the radical scavenger also includes a substance that reacts with free radicals and has the function of preventing a polymerization reaction from occurring (so-called polymerization inhibitor). The radical scavenger may be used alone or in combination of two or more types.

Radical scavengers include hindered amine compounds, hydroquinone compounds, phenol compounds, phenothiazine compounds, nitroso compounds, and N-oxyl compounds, with hindered amine light stabilizers (HALS) being particularly preferred.

Examples of radical scavengers include hindered amine compounds such as bis(1,2,2,6,6-pentamethyl-4-piperidyl)sebacate, 1-{2-(3-(3,5-di-t-butyl-4-hydroxyphenyl)propionyloxy)ethyl}-2,2,6,6-tetramethylpiperidine, and 8-acetyl-3-dodecyl-7,7,9,9-tetramethyl-1,3,8-triazaspiro{4.5}decane-2,4-dione, phenol, o-, m-, or p-crezole. phenol compounds such as 2-t-butyl-4-methylphenol, 6-t-butyl-2,4-dimethylphenol, 2,6-di-t-butyl-4-methylphenol, 2-t-butylphenol, 4-t-butylphenol, 2,4-di-t-butylphenol, 2-methyl-4-t-butylphenol, and 4-t-butyl-2,6-dimethylphenol; hydroquinone, hydroquinone monomethyl ether, methylhydroquinone, 2,5-di-t-butyl Hydroquinone compounds such as hydroquinone, 2-methyl-p-hydroquinone, 2,3-dimethylhydroquinone, trimethylhydroquinone, 4-methylbenzcatechin, t-butylhydroquinone, 3-methylbenzcatechin, 2-methyl-p-hydroquinone, 2,3-dimethylhydroquinone, trimethylhydroquinone, t-butylhydroquinone, benzoquinone, t-butyl-p-benzoquinone, and 2,5-diphenyl-p-benzoquinone; phenothiazine phenothiazine compounds such as phenylalanine, nitroso compounds such as N-nitroso-N-phenylhydroxylamine ammonium and N-nitroso-N-phenylhydroxylamine aluminum salt, and N-oxyl compounds such as 4-hydroxy-2,2,6,6-tetramethyl-piperidine-N-oxyl, 4-oxo-2,2,6,6-tetramethyl-piperidine-N-oxyl, and 4-methoxy-2,2,6,6-tetramethyl-piperidine-N-oxyl.

The coating composition for the first clear layer is preferably a water-based coating composition. In this specification, "water-based coating composition" refers to a coating composition containing water as the main solvent. The water is not particularly limited, but preferred examples include pure water such as ion-exchanged water and distilled water. In addition, when storing the coating composition for a long period of time, water that has been sterilized by ultraviolet irradiation or the like may be used to prevent the growth of mold and bacteria. In the coating composition for the first clear layer, the amount of water is preferably 20 to 80% by mass, and more preferably 30 to 70% by mass.

The coating composition for the first clear layer preferably has an ultraviolet transmittance of less than 30% when a film having a thickness of 10 μm is formed, more preferably less than 20%, and even more preferably less than 10%.

In this specification, the ultraviolet transmittance means the transmittance of light in the wavelength range from 280 nm to 400 nm, and can be measured using a spectrophotometer.
Specifically, the coating composition is applied to quartz glass so that the dry film thickness is 10 μm, and then dried in a drying oven at 80° C. for 10 minutes to prepare a sample for measurement. The ultraviolet transmittance of the sample can be measured using a UV-visible spectrophotometer (e.g., Shimadzu UV-2450).

The first clear layer coating composition may contain other components, such as other resins, solvents, pigments, surface conditioners, wetting agents, dispersants, thickeners, anti-settling agents, anti-skinning agents, anti-dripping agents, defoamers, color separation inhibitors, viscosity adjusters, rheology control agents, leveling agents, defoamers, drying agents, plasticizers, preservatives, anti-fungal agents, antibacterial agents, insecticides, antiviral agents, antistatic agents, and conductivity imparting agents, as appropriate for the purpose.

The first clear layer coating composition can be prepared by mixing various components selected as necessary. The first clear layer coating composition can be either one-component or two-component, but if it is a two-component coating composition, the base agent and curing agent are prepared in advance and mixed at the time of painting. Typically, the base agent contains a resin, and the curing agent contains a crosslinking agent. When mixing the base agent and curing agent, additives such as water or a diluent may be added for the purpose of adjusting the viscosity, etc.

The first clear layer coating composition preferably has a viscosity of 1 to 1000 (Pa·s, 23°C) at a shear rate of 0.1 (1/s), and a viscosity of 0.05 to 10 (Pa·s, 23°C) at a shear rate of 1000 (1/s). In this specification, the viscosity is measured using a rheometer (e.g., ARES rheometer manufactured by TA Instruments) after adjusting the liquid temperature to 23°C.

The coating method for the first clear layer coating composition is not particularly limited, and known coating methods such as brush coating, roller coating, trowel coating, spatula coating, flow coater coating, and spray coating (e.g., air spray coating, airless spray coating), can be used.

The drying method for the first clear layer coating composition is not particularly limited, and may be either natural drying at ambient temperature or forced drying using a dryer or the like, but forced drying is preferable when the first clear layer coating composition contains a resin with a high glass transition temperature. When the first clear layer coating composition contains a resin that contains as a component a monomer whose homopolymer Tg is 50°C or higher, it is preferable to heat dry the coating composition at 80 to 150°C after coating.

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

<Clear paint 1>
70 parts by mass of water-based resin A was added to a mixer in terms of solid content, and 20 parts by mass of light-transmitting granular material A (PMMA resin beads, particle size: 12 μm) in terms of solid content, 3.5 parts by mass of silica (median diameter (D50): 5 μm) in terms of solid content, and a total of 6.5 parts by mass of additives, thickener, dispersant, UV absorber, and light stabilizer in terms of solid content, were gradually added under stirring, and stirred for 20 minutes to prepare clear coating 1.

<Clear paint 2-14>
Clear paints 2 to 14 were prepared according to the formulations shown in Tables 1 to 3 below in the same manner as in the preparation of clear paint 1. Note that clear paint 11 had an extremely large amount of silica, so it had a high viscosity and was difficult to paint, and therefore was not evaluated as a painted body.

The materials used in the preparation of clear coatings 1 to 14 shown in Tables 1 to 3 are as follows.
Water-based resin A: styrene acrylic emulsion, solid content 43% by mass, styrene (St) content 10% by mass
Water-based resin B: acrylic emulsion, solid content 50% by mass, St amount 0% by mass
Water-based resin C: acrylic silicone emulsion, solid content 43% by mass, St amount 13% by mass
Water-based resin D: acrylic emulsion, solid content 45% by mass, St amount 0% by mass
Water-based resin E: styrene acrylic emulsion, solid content 48% by mass, St amount 29% by mass
Water-based resin F: styrene-acrylic emulsion, solid content 40% by mass, St amount 39% by mass
Water-based resin G: styrene acrylic emulsion, solid content 40% by mass, St amount 49% by mass
Water-based resin H: styrene-acrylic emulsion, solid content 47% by mass, St amount 59% by mass
Water-based resin I: acrylic fluorine emulsion, solid content 51% by mass, St amount 59% by mass
・Light-transparent particulate material A: PMMA resin beads manufactured by Sekisui Plastics Co., Ltd., median diameter (D50) 5 μm, solid content 100% by mass, visible light transmittance 90%, specific gravity 1.2
・Light-transparent particulate material B: PMMA resin beads manufactured by Sekisui Plastics Co., Ltd., median diameter (D50) 12 μm, solid content 100% by mass, visible light transmittance 90%, specific gravity 1.2
・Light-transparent particulate material C: PMMA resin beads manufactured by Sekisui Plastics Co., Ltd., median diameter (D50) 80 μm, solid content 100% by mass, visible light transmittance 90%, specific gravity 1.2
Light-transmitting granular material D: PMMA resin beads manufactured by Nippon Exlan Kogyo Co., Ltd., median diameter (D50) 150 μm, solid content 100% by mass, visible light transmittance 90%, specific gravity 1.2
・Light-transparent particulate material E: PMMA resin beads manufactured by Sekisui Plastics Co., Ltd., median diameter (D50) 200 μm, solid content 100% by mass, visible light transmittance 90%, specific gravity 1.2
Light-opaque granular material A: Silica manufactured by W. R. Grace Co., particle size 5 μm, solid content 100% by mass, specific gravity 1.8
Thickener: Polyether polyol-based urethane polymer manufactured by ADEKA Corporation, solid content 52% by mass
Dispersant: Aqueous solution of special polycarboxylate ammonium salt manufactured by San Nopco, solid content 19% by mass
Ultraviolet absorber: BASF, solid content 41% by mass
Light stabilizer: BASF, solid content 100% by mass

The values shown in columns such as "Total resins" and "Total light-transmitting granular materials" in Tables 1 to 3 represent the parts by weight of each component in the paint solids, but for the painted bodies produced according to the examples of painted body production described below, the values here can be considered as the parts by weight of each component per 100 parts by weight of the first clear layer.

<Example of the preparation of a painted body having a clear layer on the surface>
The cement-based substrate surface was coated with a clear coating by air spray to a predetermined thickness, and dried at 80°C for 5 minutes to form a clear layer. In this way, the coated bodies of Comparative Examples 1 to 3 and 6 to 9 were produced. Details of the clear coating specifications are shown in Tables 4 and 6.

<Example of preparation of a test specimen for measuring the transmittance of a painted body having a clear layer on the surface>
A clear coating prepared to a predetermined thickness was applied to the surface of the quartz glass plate by air spraying, and the coating was dried at 80°C for 5 minutes to form a clear layer. In this way, test specimens for measuring transmittance were prepared for Comparative Examples 1 to 3 and 6 to 9. Details of the clear coating specifications are shown in Tables 4 and 6.

<Example of preparation of a painted body having two or more clear layers on the surface>
A clear coating material prepared to a prescribed thickness was applied to the surface of the cement-based substrate by air spraying, and the coating was dried at 80°C for 5 minutes to form a first clear layer. Next, a coating material for a second clear layer was applied to the first clear layer by air spraying to a prescribed thickness, and the coating was dried at 80°C for 5 minutes to form a second clear layer. In this way, the coated bodies of Examples 1 to 12 and the coated bodies of Comparative Examples 4, 5, and 11 to 13 were produced. Details of the clear coating specifications are shown in Tables 4 to 8.
In the preparation of the coated bodies in Comparative Examples 11 to 13, the layers formed had low visible light transmittance and could not actually be called clear layers.

<Example of preparation of a test specimen for measuring the transmittance of a painted body having two or more clear layers on the surface>
A clear coating prepared to a predetermined thickness was applied to the surface of the quartz glass plate by air spraying, and the coating was dried at 80°C for 5 minutes to form a first clear layer. Next, a coating material for a second clear layer was applied to the first clear layer by air spraying to a predetermined thickness, and the coating was dried at 80°C for 5 minutes to form a second clear layer. In this way, transmittance measurement specimens of Examples 1 to 12 and transmittance measurement specimens of Comparative Examples 4, 5, and 11 to 13 were prepared. Details of the clear coating specifications are shown in Tables 4 to 8.

<Coating film properties: gloss>
The 60 degree gloss value and 85 degree gloss value of the prepared coated body were measured using a gloss meter VG-2000 manufactured by Nippon Denshoku Co., Ltd., and the 60 degree gloss value/85 degree gloss value value was calculated. The results are shown in Tables 4 to 8.

<Coating film properties: visible light transmittance>
The visible light transmittance of the test specimens for transmittance measurement was measured using an ultraviolet/visible/near-infrared spectrophotometer UV-3600 Plus manufactured by Shimadzu Corporation. The results are shown in Tables 4 to 8.

<Water stain evaluation>
The prepared coated bodies were immersed in room temperature water for 5 minutes, and then the condition of the coated body surface was observed and evaluated for water stains according to the following evaluation criteria. The results are shown in Tables 4 to 8.
(Evaluation Criteria)
◯: No change in appearance before and after immersion △: Wet colored areas appear on the substrate in an area of 1% or less ×: Wet colored areas appear on the substrate in an area of 1% or more

<Warm water resistance evaluation>
The prepared coated bodies were immersed in hot water at 60°C for 10 days, and the surface condition of the coated bodies was visually observed and the hot water resistance was evaluated according to the following evaluation criteria. In order to evaluate the hot water resistance, the coated bodies were taken out after immersion, the water on the surface was wiped off with a cloth, and ΔE was measured with a color difference meter. The results are shown in Tables 4 to 8.
(Evaluation Criteria)
◯: No color change occurred in the coating film before and after evaluation (ΔE≦0.2)
△: After evaluation, the coating film was slightly whitened (0.2<ΔE≦0.5)
×: After evaluation, the coating film turned white (0.5<ΔE)

<Freeze-thaw method B test>
The prepared coated bodies were subjected to a total of 200 cycles of testing, with one cycle being -20°C deep in the substrate in an air environment, followed by 10°C deep in an underwater environment. After the tests, the condition of the surface of the coated body was visually observed, and the resistance to freeze-thawing was evaluated according to the following evaluation criteria. The results are shown in Tables 4 to 8.
(Evaluation Criteria)
◯: No abnormalities such as cracks or peeling were observed on the substrate or coating film before and after the evaluation. △: After the evaluation, minor cracks or slight peeling were observed on the substrate or coating film. ×: After the evaluation, clear cracks or peeling were observed on the substrate or coating film.

<Visual appearance: Transparency>
The prepared coated bodies were visually observed and the transparency of the coated body surface was evaluated according to the following evaluation criteria. The results are shown in Tables 4 to 8.
(Evaluation Criteria)
◯: The clear layer has excellent transparency, and even after painting the clear layer, a finished appearance that makes the most of the design of the base material can be obtained.
×: The substrate can be seen from the surface of the clear layer, but the clear layer has poor transparency and the design of the substrate is impaired.
××: The base material cannot be confirmed.

<Visual appearance: Solid feel>
The prepared coated bodies were visually observed and the solid feel of the coated body surface was evaluated according to the following evaluation criteria. The results are shown in Tables 4 to 8.
(Evaluation Criteria)
○: When observed in the morning, afternoon, and evening on sunny and cloudy days, the finish has a matte, calm, and heavy feel from any angle.
×: Observed in the morning, afternoon, and evening on sunny and cloudy days, and under some conditions, depending on the angle, there was shine or glitter, and the texture was sometimes impaired. It cannot be said to have a heavy feel.
××: There is shine and glitter, and the texture is lost. Or the base material is glittering. It cannot be said to have a profound feeling.

<Accelerated weather resistance evaluation (SUV)>
The prepared coated bodies were subjected to an accelerated weather resistance test for 800 hours under the following test conditions using an SUV-W261 manufactured by Iwasaki Electric Co., Ltd.
(Test conditions)
Irradiation wavelength range: 295-450 nm, UV intensity on painted surface: 100 mW/ ^cm2 ±5%
During irradiation: Humidity 50% RH Black panel temperature 63°C ± 2°C
Condensation: 95% RH or higher Black panel temperature 40℃±2℃
Test conditions: 6 hours of irradiation/2 hours of condensation
After the test, the coated body was dried at 50°C for 16 hours, and then ΔE was measured using a color difference meter. The results are shown in Tables 4 to 8.

Claims (5)

A coated body having a substrate and at least two clear layers,
Each of the at least two clear layers contains light-transmitting granular matter having a median diameter (D50) of 10 to 200 μm, and the amount of the light-transmitting granular matter contained in each clear layer is 7% by mass or more and 35% by mass or less;
The at least two clear layers each have an average film thickness of 80 μm or less,
A coated body, characterized in that the average film thickness of the at least two clear layers as a whole is 20 μm or more . The coated body according to claim 1, characterized in that the 60 degree gloss value of the surface of the coated body is 20 or less. 3. The coated body according to claim 1 or 2, characterized in that the 85 degree gloss value of the surface of the coated body is 0.5 to 15. The coated body according to claim 1 or 2, characterized in that at least one of the at least two clear layers contains light-opaque granular material. The ratio of the 60-degree gloss value to the 85-degree gloss value on the surface of the coated body (60-degree gloss
3. The coated body according to claim 1 or 2, characterized in that the gloss value (gloss value/85 degree gloss value) is 1 to 10.